JPH08101609A - Image forming device - Google Patents

Abstract

PURPOSE: To facilitate further reduction in power consumption in a power conservation mode by cutting off a power supply to a main control part needing a high speed CPU and a large capacity memory in an image forming device having a power conservation mode. CONSTITUTION: In addition to a main control part 2 needing a high speed CPU and a large capacity memory, a sub control part composed of a low speed CPU 11 and a small capacity memory 12 is provided. In a normal mode, only the main control part 2 is actuated while in a small power mode only the sub control part is actuated. Also, the sub control part executes data transfer with external equipment, releases the small power mode when it receives data and stores the received data in a memory 1 until the main control part 2 starts.

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 having a power saving mode in which the power supply to each part of the apparatus is cut off or the supply current is reduced during standby when no processing is performed to reduce power consumption. .

[0002]

2. Description of the Related Art In recent years, protection of the global environment has been emphasized, and it has been desired to reduce electric power consumption of electric equipment from the viewpoint of resource saving. However, in offices, a large number of OA devices have been introduced to improve work efficiency, and the OA system has become large in scale year by year, so that the total power consumption thereof is considerably large. By the way, an image forming apparatus such as a copying machine or a laser printer does not always perform the original printing work, and the standby time is often longer. In view of this, a device that has been put into practical use has been put into practical use by controlling the setting temperature of the fixing heater and stopping the rotation of the polygon motor during standby.

[0003]

However, the conventional power saving control is limited to the heater, the motor, and the display unit, and does not extend to the arithmetic processing element (hereinafter referred to as CPU), the memory and other peripheral elements. It was In recent years, the power consumption of these circuits has increased due to an increase in clock speed and an increase in scale, and they have become non-negligible sources of power consumption. Although it is conceivable to stop the CPU in order to reduce the power consumption of this portion, if this is done, communication with an external device cannot be performed, and for example, the printer cannot receive a print command from the host computer. There was a problem.

The present invention has been made in view of the above points, and in an image forming apparatus having a power saving mode, C
It is an object of the present invention to reduce power consumption in PUs, memories, etc. and realize further power saving. Another object is to prevent the reception data from being lost from the external device in the power saving mode.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and aims to reduce power consumption by reducing or interrupting power supply to each part of the apparatus during standby when no processing is being performed. In an image forming apparatus having a power saving mode, a main control section for controlling each section of the apparatus and a sub control section for controlling an interface with an external device are provided, and during the standby mode, the main control section is stopped and only the sub control section is provided. It is configured to work.

The sub-control unit has a storage means,
When data is received from an external device in the standby mode, the storage of data in the storage means is started and the main control section is restored.

[0007]

According to the first aspect of the invention, during the power saving mode, the main control unit including the high-performance CPU and the large-capacity memory is stopped and only the sub-control unit is operated, so that the power consumption in the control unit is reduced. Can be made.

Further, according to the second aspect of the invention, since the reception data is stored in the storage means in the sub-control unit until the main control unit becomes operable, the data reception is performed before the rising of the main control unit. Even if it starts, there will be no missing data.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a block diagram of a printer which is an image forming apparatus according to the present invention. The printer 1 is connected to a host computer 13 via an interface unit 3, and the interface unit 3 is composed of a sub CPU 11 that controls communication in the power saving mode and a memory 12 that holds received data. The sub CPU 11 and the memory 12 correspond to the sub control unit of the present invention. The main control unit 2 controls the entire printer 1, and includes a main CPU 5, a ROM 6 that stores a control program, and a RAM that stores temporary data.
It consists of 7.

The power controller 4 is a CPU 5 or 11
The power supply to each part of the printer is controlled by an instruction from the. The operation unit 8 includes an operation key unit for the user to set various printing conditions such as the number of prints, density, and font selection.
An LCD display unit for displaying the setting status, guidance, etc. The image forming unit 9 includes a paper feeding unit, a printing unit, a developing unit, a transfer unit,
It consists of a paper ejection unit, and receives instructions from the main control unit 2.
The received image data is printed on recording paper by a known electrophotographic method. Each unit is connected via a common data bus 10.

The roles of the main controller 2, the sub CPU 11 as the sub controller, and the memory 12 will now be described. The main controller 2 develops the data received from the host computer 13 into a bitmap, controls the temperature of the fixing unit, stabilizes the amount of laser light, controls the timing of paper conveyance, etc.
Since it is necessary to perform various processes at high speed, a high-performance CPU such as 16-bit or 32-bit is used, and a high clock frequency is required. In addition, a memory with a large capacity is required to store and expand image data, and DRAM is used in consideration of cost.
Is often used. As described above, since the main control unit is built with a large-scale and high-performance circuit, power consumption is inevitably large.

On the other hand, the sub-control unit only needs to send and receive data to and from the host computer, so that a CPU having about 8 bits is sufficient. Further, the memory 12 need only hold the data received from the host computer 13 until the main control unit 2 starts up and becomes operable.
If the RAM is used, the refresh operation becomes unnecessary, so that the power consumption can be further suppressed.

Next, the operation for entering the power saving mode will be described with reference to the flowchart of FIG. FIG. 2 shows a process in the main CPU 5, and after a lapse of a fixed time (for example, 3 minutes) from the end of data reception from the host computer, the subsequent process is performed to enter the power saving mode (step S1). Although the power saving mode is entered depending on the time from the end of data reception here, the power saving mode may be changed depending on the elapsed time from the end of the printing operation or the user's operation or a specific key operation. When entering the power saving mode, first the driving of the sub CPU 11 is started (step S2), and thereafter, the sub CPU 11 performs the data reception process from the host computer 13.
Next, the power supply controller 4 is turned off to cut off the power supply to each part of the device (step S3). However, only the interface unit 3 is driven by another power source (not shown). As a result, the main CPU 5 also stops, and thereafter the power saving mode is entered.

During the power saving mode, the power supply to the sub CPU 11 and the memory 12 of the interface unit 3 is cut off. When a print command is sent from the host computer 13 in this state, the power saving mode is released. The operation at this time will be described with reference to the flowcharts of FIGS.

FIG. 3 shows the processing in the sub CPU. When a print request is issued from the host computer 13, the following processing is performed to cancel the power saving mode (step S1).
0). When receiving the print request, the sub CPU 11 starts data reception without causing the host computer 13 to wait (step S11). At this point, the power saving mode is still in effect and the main controller 2 is not operable, so the received data is stored in the memory 12. As a result, it becomes possible to receive data even before the main control unit 2 is started up, and it is possible to prevent missing of received data. Next, the power supply controller 4 is turned on to start supplying power to each part of the apparatus, and drive of the main CPU 5 is started (steps S12 and S13). The main control unit 2 (main CPU 5, RAM 7) can immediately operate even if power supply is started (a state in which received data can be received)
Therefore, the loop is repeated until the main control unit 2 becomes operable, and when the OK signal is received from the main control unit 2, the sub CPU 11 stops and the power saving mode ends (steps S14 and S15).

FIG. 4 shows the main CPU when the power saving mode is released.
This is the process in 5. When the power controller is turned on by the sub CPU 11 and the main CPU 5 starts driving,
First, the main CPU 5 itself and the RAM 7 are self-checked (step S20). When the check is completed and the operation is ready, an OK signal is transmitted to the sub CPU 11 (step S22). Next, the received data stored in the memory 12 is read out and transferred to the RAM 7 in the main controller 2 (step S23). When the transfer is completed, the data reception process is taken over from the sub CPU 11 (step S24), and thereafter, the main CPU 5 performs the data reception process and the sub CPU 11 stops. At this point, the power saving mode has been canceled. When reception of all data is completed, printing is performed (step S25), and the process is completed.

[0017]

As described above, according to the image forming apparatus of the present invention, the sub-control unit is provided in addition to the main control unit, and only the main control unit is operated during the normal operation and the power saving mode is set. Since only the sub-control unit is operated, it is possible to cut off the power supply to the CPU and the memory that consume a large amount of power during the power saving mode, and it is possible to significantly reduce the power consumption. Further, since the sub CPU takes charge of data exchange with the external device during the power saving mode, it is possible to receive instructions and data from the external device even during the power saving mode in which the power of the main control unit is cut off. Furthermore, by providing a small-capacity memory on the sub CPU side, data reception can be started even in a state where the main control unit is not operable in the low power mode, and the received data is stored in this memory. Therefore, data loss can be prevented.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a printer which is an image forming apparatus according to the present invention.

FIG. 2 is a flowchart showing a process of a main CPU 5 when entering a power saving mode.

FIG. 3 is a sub-C when data is received in the power saving mode.
It is a flow chart which shows processing of PU11.

FIG. 4 is a main CPU 5 when the power saving mode is released.
It is a flowchart which shows the process of.

[Explanation of symbols]

1: Printer body 2: Main control unit 3:
Interface part 4: Power supply controller 5: Main CPU 6:
ROM 7: RAM 11: Sub CPU 1
2: Memory 13: Host computer

Claims (2)

[Claims] 1. An image forming apparatus having a power saving mode for reducing power consumption by reducing or cutting off power supply to each section of the apparatus during standby when no processing is being performed, and a main control section for controlling each section of the apparatus. An image forming apparatus, comprising: a sub-control unit for controlling an interface with an external device, wherein the main control unit is stopped and only the sub-control unit operates during a power saving mode. 2. The sub-control unit has a storage unit, and when receiving data from an external device in the standby mode, starts storing data in the storage unit and restores the main control unit. The image forming apparatus according to claim 1.