JPH08156316A - Image forming device - Google Patents

Abstract

PURPOSE: To reduce power consumption without sacrificing an operation time for a first copy at the starting time of motors in an image forming device such as a laser beam printer. CONSTITUTION: Each driving motor is controlled to have an application voltage 12V and the number of revolutions N3 during standby. At the time of copying operation, a voltage is applied to a driving motor of a first polygon K, the voltage rises to 24V and the number of revolutions reaches the number of revolutions N5 of writing time. During that time, a detecting device detects the voltage. When the detecting device detects 18V, a detection signal is outputted to a control device which outputs an application signal of the voltage to a second polygon Y so as to start the driving motor. Likewise, when the voltage of the second polygon Y reaches 18V, a driving motor of a third polygon M is started. When the voltage of the third polygon M reaches 18V, a fourth polygon C is started so as to sequentially raise rotation of each polygon mirror to the number of rotations of the writing time. Thus, power consumption can be saved by time lag of start timing of the driving motors and an influence on the operation time of a first copy due to ensuring of the control mechanism can be eliminated.

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 view of a laser beam printer, in which laser light emitted from a laser emission unit 11 of a laser optical scanning device is deflected by a rotating polygon mirror (polygon mirror) 12 that rotates at high speed, and passes through a lens 13. The photoconductor 14 is scanned. In such an apparatus, its mission is to perform high-speed processing, and in particular, a drive motor such as a polygon motor for driving an optical scanning system is required to have a short start-up time and power saving. Therefore, in order to satisfy these requirements, a method of monitoring the temperature of the fuser and sequentially starting the polygon drive motors by a signal generated by detecting the fuser temperature in the preceding stage (Japanese Patent Laid-Open No. 64-797).
Japanese Patent Laid-Open No. 62-161177 discloses a method of reducing the load on the power source by arranging each polygon to start up sequentially with a predetermined time difference. In these methods, the rise time difference of the polygon drive motor has an influence on the time required for the first copy (first copy) when the copying operation is shifted from the standby state.

[0003]

Therefore, the present invention provides an image forming apparatus capable of achieving lower power consumption without sacrificing the time required for the first copy.

[0004]

SUMMARY OF THE INVENTION An image forming apparatus according to the present invention comprises a plurality of laser optical scanning devices arranged on a sheet conveyance path, a drive motor for rotationally driving the laser optical scanning devices, and a drive motor drive. When the detection signal from the detection means for detecting the state and the detection means for the drive motor of the laser optical scanning device arranged in the preceding stage during image formation is input, the drive motor of the laser optical scanning device arranged in the next stage And a control device for outputting a rotation drive signal.

[0005]

Since the start timings of the laser optical scanning device of the previous stage and the laser optical scanning device of the next stage are shifted, they can be driven with low power and the inrush current can be suppressed.

[0006]

Embodiments of the present invention will be described with reference to the drawings. FIG.
2 is a schematic diagram of a tandem full-color copying machine which is an image forming apparatus shown in this embodiment, and FIG. 2 shows a start timing of a rotary polygon mirror (polygon mirror) of each laser optical scanning device and a writing timing on a sheet. The sheet 50 is placed on the conveyor belt 55, and is conveyed and moved in the arrow A direction. At the time of movement, the paper 50 is black by the first polygon K, yellow by the second polygon Y, magenta by the third polygon M, cyan by the fourth polygon C,
The images of the above colors are sequentially overlapped and written, and the paper on which the full-color copying is finished is finally output. Each laser optical scanning device is provided with a detection device 61, 62, 63, 64 for detecting the condition of the polygon mirror drive motor. During the copy operation of the image forming apparatus, when the paper 50 reaches the first polygon Y, it is not necessary that the drive motors of the polygon mirrors of the respective colors be simultaneously raised to the number of rotations required for the copy operation. That is, in the image forming apparatus, in each of the polygon motors rotating at the rotation speed N ₃ in the standby state, the rotation speed N is the rotation speed of only the polygon motor that writes the paper 50 reaching the lower portion of the image writing portion. _It may be controlled by the control device in synchronism with the transfer of paper so that the number becomes ₅ . Therefore, the image forming apparatus of the present invention controls the rotation of the polygon mirror of the laser optical scanning device arranged at the next position according to the detection signal from the detection device arranged in the laser optical scanning device at the preceding stage. ing.

Next, the control of the drive motor by the control device of the image forming apparatus will be described. First Embodiment This embodiment shows a case where the drive voltage of the polygon mirror is detected and the drive motor is controlled by the voltage detection signal (see FIGS. 2 and 3). The detection device detects the voltage applied to each drive motor. Then, the control device controls the rotation of the second polygon Y arranged at the next position by the input voltage signal of the first polygon K positioned at the frontmost stage. Further, the voltage signal of the second polygon Y controls the rotation of the third polygon M arranged at the next position, and the voltage signal of the third polygon M controls the rotation of the fourth polygon M arranged at the next position. The rotation of the polygon C is controlled.

The operation timing by voltage detection will be described with reference to FIG. In this embodiment, the sensing device has an applied voltage of 1
An example is shown in which a detection signal is output when the voltage becomes 8V. During standby, the applied voltage 1 is applied to the first polygon K, the second polygon Y, the third polygon M, and the fourth polygon C.
It is controlled to 2V and the rotation speed N ₃ . A copy command is issued and the copy operation starts at time t ₁ . The first polygon K, which the paper 50 reaches first, immediately increases the rotational speed and the applied voltage, and accelerates the voltage to 24 V and the rotational speed N ₅ . The detection device 61 detects the applied voltage of the first polygon K and outputs a detection signal to the control device at time t ₂ when the applied voltage reaches 18V. The control device outputs a drive signal to the second polygon Y in response to this detection signal. For the second polygon Y, the applied voltage is increased to accelerate the rotation, and the applied voltage is 24 V and the rotation speed is N ₅ immediately before the writing timing. Then, at time t ₃ when the applied voltage becomes 18 V, the detection device 62 outputs a detection signal to the control device, and the control device outputs a drive signal to the third polygon M in response to this detection signal. Similarly, the detection device 6 for the third polygon M
At time t ₄ when the detection signal of 3 is input, the fourth polygon C
The drive signal is output to the drive motor of.

Next, assuming that the voltage supplied to the driver circuit of the polygon mirror drive motor is 24V, the voltage is 18V.
The control by means of FIG. The supply voltage Vin to the driver circuit 60 of each laser optical scanning device is set to 24
The output voltage Vout to the drive motor 100 is set to 12V during standby, and is increased to 24V during writing. The voltage of the first polygon K increases as the copying starts. The rotation speed increases as the voltage increases and reaches the write rotation speed N ₅ . When a voltage of 18 V is detected by the detection device 61 during this time (time t ₂ ), a start signal is output to the second polygon Y, the voltage of the second polygon Y is increased to increase the rotation, and the number of rotations for writing. Reach up to N ₅ . During this time, when the voltage 18V of the second polygon Y is detected by the detection device 62, a start signal is output to the third polygon M (time t ₃ ), the voltage is applied, and the rotation is written to the rotation speed N ₅ Give up. During this time, when the voltage 18V of the third polygon M is detected by the detection device 63,
A start signal is output to the fourth polygon C, a voltage is applied, and the number of rotations N ₅ for writing is increased (time t ₄ ).
In this way, the polygon mirror drive motor is controlled by using the specified voltage as the detection voltage, and the polygon mirror drive motor is started at intervals that match the time required for the paper 50 to move between the laser optical scanning devices. Therefore, the power consumption immediately after startup can be reduced and the noise generated from the device at startup can be suppressed. In addition, the power supply capacity can be reduced.

Second Embodiment This embodiment shows a case where the detection device detects the drive current of the polygon mirror and controls by a detection signal which detects the specified current. The detection device detects the current applied to each drive motor, and the control device controls the rotation of the second polygon Y arranged at the next position according to the input current signal of the first polygon K located at the preceding stage. . The current signal of the second polygon Y controls the rotation of the third polygon M arranged at the next position, and the current signal of the third polygon M controls the rotation of the fourth polygon M arranged at the next position. The rotation of the polygon C is controlled.

The control of the drive motor by current detection will be described with reference to FIG. In this embodiment, the applied current during writing is 2
In the case of A, the detection device outputs a detection signal when the applied current becomes 1A. During standby, the first polygon K, the second polygon Y, the third polygon M, and the fourth polygon C have an applied current of 0.5 A and an applied voltage of 1
It is controlled to 2V and the rotation speed N ₃ . A copy command is issued and the copy operation starts at time t ₁ . The first polygon K, which the paper 50 reaches first, immediately changes the applied voltage to 2
The applied current is raised to 2 A at 4 V and accelerated to reach the rotation speed N ₅ . The detection device 61 is the first polygon K.
The time t ₂ when the applied current becomes 1A by detecting the applied current of
At this time, a detection signal is output to the control device. The control device outputs a drive signal to the second polygon Y in response to this detection signal. The second polygon Y increases the applied voltage to 24V,
The applied current is increased to 2 A and accelerated to reach the rotation speed N ₅ . Then, at time t ₃ when the applied current becomes 1 A, the detection device 62 outputs a detection signal to the control device, and the control device outputs a drive signal to the third polygon M in response to this detection signal. In this way, the drive signal is output to the drive motor of the fourth polygon C at time t ₄ when the detection signal of the detection device 63 of the third polygon M is input. As described above, since the drive motors of the respective polygon mirrors are started at intervals that match the time required to move the paper 50 between the laser optical scanning devices, it is possible to suppress the inrush current immediately after the start. Therefore, the power supply capacity can be reduced.

Third Embodiment In this embodiment, the detecting device detects the number of revolutions of the polygon mirror, and controls by the detection signal which detects the prescribed number of revolutions. The detection device detects the rotation speed of each drive motor, and the control device rotates the rotation speed of the second polygon Y arranged at the next position based on the rotation speed detection signal of the input first polygon K. To control. Then, the rotation of the third polygon M arranged at the next position is controlled by the detection signal of the rotation number of the second polygon Y, and the third polygon M is controlled.
The rotation speed signal controls the rotation of the fourth polygon C arranged at the next position.

The control of the drive motor based on the rotation speed detection will be described with reference to FIG. In this embodiment, when the number of revolutions at the time of writing is 20,000 rpm, the detection device has a number of revolutions of 18,0.
A detection signal is output when it reaches 00 rpm. During standby, the first polygon K, the second polygon Y, the third polygon M, and the fourth polygon C have a rotational speed of 1
It is controlled at 10,000 rpm. A copy command is issued and the copy operation starts at time t ₁ . The first polygon K on which the paper 50 first arrives immediately accelerates its rotation and increases its rotation speed. The detection device 61 has a rotation speed of 18,000 rp
At the time t ₂ when m is detected, a detection signal is output to the control device. Based on this detection signal, the control device outputs a drive signal to the second polygon Y, and the second polygon Y accelerates its rotation so that the rotation number becomes N ₅ immediately before the writing timing. Meanwhile, the detection device 62 detects the rotation speed of 18,000 rpm at time t ₃ , outputs a detection signal to the control device, and the control device outputs a drive signal to the third polygon M in response to this detection signal. And the third polygon M
At the time t ₄ when the detection signal of the detection device 63 of
The drive signal is output to the drive motor for polygon C. In this way, the control device activates the rotation of the polygon mirror by detecting the rotation number of the drive motor of the polygon mirror of the detection device. Since the drive motor of the next stage can be started by the time difference corresponding to the number of revolutions and the number of revolutions can be reliably set to the number of revolutions at the time of writing at the specified time, the operation time of the first copy is not affected.

[0014]

The image forming apparatus of the present invention has the following effects. 1. By shifting the start timing of the drive motor of the laser optical scanning device, it is possible to reduce the load of the power supply due to the start current in the case of simultaneous startup as much as possible, and
The power supply capacity can be suppressed, and as a result, power consumption at startup can be reduced. 2. Since the drive motor of the next stage laser optical scanning device is activated by the detection signal of the power supply / voltage / rotation speed from the detection device, there is less time loss compared to the case where the READY signal is used as in the conventional case. Further, all the drive motors can be sequentially started up more efficiently, the start-up time is reliable, and the operation time of the first copy is not affected.

3. In the case of voltage control, since the voltage is applied with time, the noise at startup can be suppressed as much as possible. 4. In the case of current control, the inrush current can be suppressed as much as possible because it is driven at a low voltage immediately after startup. 5. In the case of rotation speed detection, the drive motor can be started with a time difference corresponding to the rotation speed immediately before starting, as compared to the method of starting with a predetermined time difference, so it is possible to ensure the rise time while saving energy. Therefore, it does not affect the operation time of the first copy. 6. In addition to achieving low power consumption during standby, noise and temperature rise during standby can be prevented.

[Brief description of drawings]

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

FIG. 2 is a timing chart of rotation of each drive motor and applied voltage.

FIG. 3 is a timing chart of rotation of each drive motor and applied voltage.

FIG. 4 is a circuit block diagram of a drive motor.

FIG. 5 is a timing chart of rotation of each drive motor and applied current.

FIG. 6 is a timing chart of rotation of each drive motor.

FIG. 7 is a schematic diagram of a laser optical scanning device.

[Explanation of symbols]

50 paper, 55 belt, 60 driver circuit,
100 Motor, K 1st polygon, Y 2nd polygon, M 3rd polygon, C 4th polygon.

Claims (5)

[Claims] 1. A plurality of laser optical scanning devices arranged on a sheet conveyance path, a drive motor for rotationally driving the laser optical scanning device, detection means for detecting a drive state of the drive motor, and rotation of the drive motor. And a control device for controlling the laser, which is arranged in the next stage when the detection signal from the detection means of the drive motor of the laser optical scanning device arranged in the preceding stage is input during image formation. An image forming apparatus configured to output a drive signal to a drive motor of an optical scanning device. 2. The image forming apparatus according to claim 1, wherein the detecting means detects an applied voltage of the drive motor. 3. The image forming apparatus according to claim 1, wherein the detecting means detects an applied current of the drive motor. 4. The image forming apparatus according to claim 1, wherein the detection unit detects the rotation speed of the drive motor. 5. The image forming apparatus according to claim 1, wherein the supply voltage during standby is less than or equal to the supply voltage during image formation.