JPH08129287A - Image forming device - Google Patents

Abstract

PURPOSE: To attain a low power consumption without sacrificing operation time required for first copying. CONSTITUTION: When the image forming device is turned on, the user immediately starts the operation, and a laser optical scanning device starts rotating after a fixed time t1 . As for an impressed current (or voltage in some ceses) at the time of start-up, a limiter for the impressed current A3 is arranged, and the rotating speed in a standby time is set N3 . The impressed current A3 of the limiter is set below an impressed current A4 at the time of starting printing, a rush current at the time of start-up is made lower so as to reduce a load applied on a power source. And also, plural laser optical scanning devices are successively controlled so as to rise, then, a low power consumption is attained, and also, each color laser optical scanning device already reaches a required rotating speed at the time of writing an image, so that the first copying is not affected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a laser beam printer which processes an image with a digital signal and obtains a hard copy from the signal.

[0002]

2. Description of the Related Art An example of this type of image forming apparatus will be described with reference to FIG. This drawing shows a schematic diagram of a laser beam printer, in which laser light emitted from a laser emitting section 11 is deflected by a rotating polygon mirror 12 rotating at a high speed, and a lens 13
The photoconductor 14 is scanned via the. In such an apparatus, its mission is to perform high-speed processing, and in particular, a drive motor for a rotary polygon mirror in an optical scanning system is required to have a short start-up time and power saving. Therefore, in a device equipped with a plurality of rotary polygon mirror devices, a method of monitoring the temperature of the fuser and sequentially starting drive motors of the rotary polygon mirror (see Japanese Patent Laid-Open No. 64-79759) and a laser for printing work A method of reducing the power consumption by driving only the optical scanning device (see Japanese Patent Laid-Open No. 246069/1990), and further, a configuration in which the respective optical scanning devices are sequentially started with a predetermined time difference, Japanese Patent Laid-Open No. 62-161177 discloses a method for reducing the load, but these methods are the first copy when the rise time difference of the drive motor of the rotary polygon mirror shifts from the standby state to the copy operation. It affected the operation time of (first copy). To reduce the operation time of the first copy, when a print signal is received, a pseudo start signal is output, the standby mode is released, the user starts up, the rotation of the rotary polygon mirror is started, etc. , JP-A-60-86573.

[0003]

SUMMARY OF THE INVENTION Therefore, the present invention provides an image forming apparatus capable of achieving lower power consumption without sacrificing the operation time of the first copy.

[0004]

An image forming apparatus of the present invention includes a laser optical scanning device, a drive motor for rotationally driving the laser optical scanning device, and a drive signal for the drive motor for a predetermined time when the image forming apparatus is started. The control device stops the output and outputs a drive signal to the limiter circuit for the applied current or the applied voltage after a predetermined time elapses.

[0005]

When the image forming apparatus is started up, it takes time for the temperature to rise. In accordance with the start-up time of the fuser, the rotation of the drive motor is started and the voltage and current required to reach the standby speed are limited. By applying, power saving is achieved.

[0006]

Embodiments of the present invention will be described with reference to the drawings. FIG.
FIG. 2 is a schematic diagram of a tandem full-color copying machine embodying the present invention, and FIG. 2 shows the starting timing of the rotary polygon mirror of each laser optical scanning device and the writing timing on paper. The sheet 50 is placed on the conveyor belt 55, and the arrow A
It is transported and moved in the direction. At the time of movement, the sheet 50 forms an image of yellow by the first optical scanning device Y, magenta by the second optical scanning device M, cyan by the third optical scanning device C, and black by the fourth optical scanning device K. The sheets are sequentially overwritten and output, and finally, the paper for which full-color copying has been completed is output. During this copy operation, when the paper 50 reaches the first optical scanning device Y, it is not necessary that the drive motors of the rotary polygon mirrors of the respective colors be simultaneously raised to the number of rotations required for the copy operation. When power is input to the image forming apparatus, the device is in a standby state before the copy operation is started or during the copy operation. Therefore, in the standby state of this image forming apparatus, the control device drives the drive motor of the rotary polygon mirror at a rotation speed N ₃ (≧ 0) lower than the rotation speed at the time of image formation. Then, when the sheet 50 reaches the lower part of the writing portion of each optical scanning device, it is driven by a controller (not shown) so that the corresponding rotary polygon mirror has a specified rotation, in this embodiment, the rotation speed N _5. It controls the motor.

The rotation of each rotary polygon mirror and the timing of image formation will be described with reference to the timing chart shown in FIG. In the first optical scanning device Y, since the paper 50 reaches the first time ty, the motor is driven at the rising edge indicated by the line y with the maximum acceleration so that the rotary polygon mirror Y reaches the rotation speed N ₅ at the time ty. To drive. Image formation is executed from time ty when the number of rotations reaches N ₅ . Since the sheet 50 reaches the time tm, the second optical scanning device M drives the motor at the acceleration indicated by the line m so that the rotary polygon mirror M reaches the rotation speed N ₅ at the time tm. Image formation is executed from time tm when the number of rotations reaches N ₅ . In the third optical scanning device C, when the paper 50 is at time t
Since it reaches c, the rotating polygon mirror C rotates at the number of revolutions N at time tc.
_As shown in Fig. 5, the motor is driven with the acceleration shown by the line c. Image formation is executed from the time tc when the number of rotations reaches N ₅ . Since the paper 50 reaches the time tk, the fourth optical scanning device K drives the motor at the acceleration indicated by the line k so that the rotary polygon mirror K reaches the rotation speed N ₅ at the time tk. Image formation is executed from time tk when the number of rotations reaches N ₅ .

Next, the control of the drive motor of the rotary polygon mirror at the time of starting the image forming apparatus will be described. (1) Control by applied current (see FIG. 3). Standby Normally, the time required for the user to raise the temperature to the standby set temperature C ₃ after the device is started is longer than the time required for the rotary polygon mirror to increase the rotation speed to the standby set rotation speed N ₃ . Therefore, the fuuser starts heating at the time t ₀ when power is input to the image forming apparatus. For the fuuser, the rotary polygon mirror starts to rotate with a sufficiently slow rise. As a result, the inrush current can be suppressed as much as possible. Then, when a copy command is input at time t ₃ , the fuser temperature rises from the standby temperature C ₃ to the print temperature C ₅ by the time t ₅ when the printing operation starts, and the rotation of the rotary polygon mirror is stopped. The number of revolutions N _{3 is} increased to the number of revolutions N ₅ during printing.

The control of the rotation of each drive motor at this stage is as follows. Driving 1 The fuuser is in the operating state and the rotary polygon mirror is not driven for a predetermined time (from time t to time t ₁ ). Drive 2 The drive motor of the rotary polygon mirror is driven at time t ₁ for a predetermined time. At this time, the limiter A ₃ is added to the current control circuit.
The current circuit is set, and the current circuit is controlled so as to select the limiter circuit at the start of driving. The rotation of the rotary polygon mirror reaches N ₃ , and the voltage is restricted to V ₁ and the current is restricted to A ₁ . When a print start signal is input at driving 3 hours t ₃ ,
The rotation of the rotary polygon mirror is accelerated to a rotation speed N ₅ . Time t ₅ before the time t ₅ when the user temperature becomes the print temperature C _5
The rotating polygon mirror has a rotating speed of N ₅ . The applied current at this time is A ₄ . When the number of rotations of the drive 4 becomes N ₅ (time t ₄ ), the voltage is V ₂
The current is controlled to A ₂ . The above drive currents are controlled so that A ₁ <A ₂ <A ₃ <A ₄ . In this way, this control selects the limiter circuit for the applied current at the start in the rotational driving of the rotary polygon mirror, so that the inrush current can be further suppressed.

(2) Control by applied voltage (see FIG. 4). The relationship between the increase in the fusible temperature at the start of the standby device and the increase in the rotational speed of the rotary polygon mirror is the same as in (1). Therefore, for the fuuser that starts heating at the same time as the time t ₀ when power is input to the image forming apparatus, the rotary polygon mirror starts rotating at a sufficiently slow rising edge. Then, when a copy command is input at time t ₃ , the fuser temperature is the standby temperature C ₃ by time t ₅ when the printing operation is started.
To the print temperature C ₅ and the rotation of the rotary polygon mirror is increased from the standby rotation speed N ₃ to the printing rotation speed N ₅ .

The control of the rotation of each drive motor at this stage is as follows. Driving 1 The fuuser is in the operating state and the rotary polygon mirror is not driven for a predetermined time (from time t to time t ₁ ). . Drive 2 The drive motor of the rotary polygon mirror is driven at time t ₁ for a predetermined time. At this time, the limiter V ₃ is added to the voltage control circuit.
A voltage circuit set with is set, and the voltage circuit is controlled so that the limiter circuit is selected at the start of driving. The rotation of the rotary polygon mirror reaches N ₃ , and the voltage is restricted to V ₁ and the current is restricted to A ₁ . When a print start signal is input at driving 3 hours t ₃ ,
The rotation of the rotary polygon mirror is accelerated to a rotation speed N ₅ . Time t ₅ before the time t ₅ when the user temperature becomes the print temperature C _5
The rotating polygon mirror has a rotating speed of N ₅ . The applied voltage at this time is V ₄ . When the number of rotations of the drive 4 becomes N ₅ (time t ₄ ), the voltage is V ₄
The current is controlled to A ₂ . The above drive voltages are controlled so that V ₁ <V ₂ <V ₃ <V ₄ is satisfied. Further, in these embodiments, the rotation control of the rotary polygon mirror at the time of startup is controlled by time. It may be configured to start.

As described above, this control selects the limiter circuit for the applied voltage at the start in the rotational driving of the rotary polygon mirror, so that the power consumption of the device can be reduced. Further, when the frequency of use of each optical scanning device is the highest in the fourth optical scanning device K, the fourth optical scanning device K is arranged at the most downstream side as shown in this embodiment. According to this arrangement, the fourth optical scanning device K takes the longest time to reach the sheet. Therefore, it is possible to increase the time required from the stand-by rotation at the rotation speed N ₃ to the rotation at the time of printing at the rotation speed N ₅ , do not require rapid acceleration, and reduce power consumption at startup. You can For example, in the case of a system in which the power supply (24V) is divided into two or more, the power supply with the smallest current capacity may be turned on.

In this image forming apparatus, the drive motor of each rotary polygon mirror is rotated at a rotational speed lower than the rotational speed required for image writing or is stopped during standby.
In addition to saving power during standby, noise and temperature rise of the device can be prevented. Further, when the power of the image forming apparatus is input, there is a time lag between the operation of the fuser and the rotation operation of the rotary polygon mirror, and the limiter is set for the current or voltage, so the inrush power consumption of the equipment can be reduced. , The load on the power supply can be reduced. Since each rotating polygon mirror has reached the number of rotations required for printing when the paper arrives, the first copy time is not sacrificed.

Further, since the drive time of the drive motor of the rotary polygon mirror disposed in the subsequent stage (downstream of the sheet conveying path) is increased during the printing operation, the start-up of the conventional apparatus in which a plurality of drive motors are simultaneously activated. It has a considerable noise prevention effect compared to the noise of the time. By setting the acceleration of the rotation of the rotary polygon mirror in standby in order of earlier operation timing, it is possible to save power and not to affect the startup time at the start of the copy operation.

[0015]

In the image forming apparatus of the present invention, the drive motor of the rotary polygon mirror is rotated at a rotation speed lower than the rotation speed required for image writing at the standby time or at a stop, so that power saving at the standby time is achieved. In addition, the noise and temperature rise of the device can be prevented. Further, when the power of the image forming apparatus is input, there is a time lag between the operation of the fuser and the rotation operation of the rotary polygon mirror, and the limiter is set for the current or voltage, so the inrush power consumption of the equipment can be reduced. , The load on the power supply can be reduced.

Also in an image forming apparatus having a plurality of laser optical scanning devices, power consumption can be saved by sequentially setting the acceleration of the rotation of the rotary polygon mirror during standby in order of earlier operation timing. In addition, the startup time at the start of the copy operation is not affected. When only the most frequently used laser optical scanning device is used, for example, in a system in which a 24V power supply is divided into two or more, only the power supply with the smallest current capacity needs to be turned on, and therefore power consumption can be reduced. Can be realized.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a tandem full-color copying machine.

FIG. 2 is a timing chart of starting and writing of the rotary polygon mirror.

FIG. 3 is a timing chart of a temperature rise of a fuuser at the time of startup, rotation of a rotary polygon mirror, and voltage limitation.

FIG. 4 is a timing chart of the temperature rise of the fuuser at the time of startup, rotation of the rotary polygon mirror, and current limitation.

FIG. 5 is a rotation and writing timing chart of a fourth rotary polygon mirror K.

FIG. 6 is an explanatory diagram of a laser optical scanning device.

[Explanation of symbols]

50 sheets, 55 belts, Y first optical scanning device, M second optical scanning device, C third optical scanning device, K fourth optical scanning device.

Claims (6)

[Claims] 1. A laser optical scanning device having a rotary polygon mirror, a drive motor for rotationally driving the rotary polygon mirror, and a control device for controlling the rotation of the drive motor. A limiter circuit for the applied current is provided, and the control device is configured to stop the output of the drive signal to the drive motor for a predetermined time when the image forming apparatus is started, and output the drive signal to the limiter circuit after the predetermined time has elapsed. Image forming apparatus. 2. A laser optical scanning device having a rotary polygonal mirror, a drive motor for rotationally driving the rotary polygonal mirror, and a control device for controlling the rotation of the drive motor. A limiter circuit for the applied voltage is provided, and the control device is configured to stop the output of the drive signal to the drive motor for a predetermined time when the image forming apparatus is started, and to output the drive signal to the limiter circuit after the elapse of the predetermined time. Image forming apparatus. 3. An image forming apparatus having a plurality of laser optical scanning devices having a rotary polygon mirror on a sheet conveyance path, wherein a rotation control device for a drive motor of the rotary polygon mirror has each rotary polygon mirror in a standby state. Is set to a rotational speed lower than the rotational speed during printing, and when the print command is input, the acceleration of the rotary polygon mirror drive motor in the laser optical scanning device arranged on the most upstream side of the conveyance path is set to the highest. ,
An image forming apparatus that outputs a rotational drive signal with a sequentially reduced acceleration to a laser optical scanning device disposed on the downstream side. 4. An image forming apparatus having a plurality of laser optical scanning devices having a rotary polygon mirror on a sheet conveyance path, wherein the controller is arranged at the most upstream side of the conveyance path when a print command is input. 3. The laser driving signal of the laser optical scanning device according to claim 1, wherein the acceleration of the driving motor of the laser optical scanning device is maximized, and the rotational driving signal is sequentially output to the laser optical scanning device disposed on the downstream side. Image forming device. 5. The image forming apparatus according to claim 3, wherein a frequently used laser optical scanning device is arranged on the downstream side of the conveyance path. 6. The control device outputs a drive signal to a limiter circuit of a rotation drive control circuit when the temperature of the fuser is detected and the detected temperature is a predetermined temperature.
The image forming apparatus described.