JP2004085722A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a malfunction of an image forming apparatus which has two CPUs and stops supply of power to one of the CPUs in a power saving mode. <P>SOLUTION: The image forming apparatus has the two CPUs (102) and (103). The CPU (102) switches between a standby mode and the power saving mode, according to switching time stored in a memory (104) and actual time output from an RTC (105). The CPU (103) gives the actual time from the RTC (105) to the CPU (102). However, supply of power to the CPU (103) is stopped in the power saving mode. As the CPU (103), one having the function of stopping the operation of itself during the supply of power thereto is used. Before switching to the power saving mode, the operation of the CPU (103) is stopped by an instruction from the CPU (102), thereby preventing wrong actual time from being given to the CPU (102) at the time of switching. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus for forming an image on a sheet, such as a copying machine, a facsimile machine, and a printer, and more particularly, to an image forming apparatus having a power saving mode in which power supply to a power consuming portion is stopped.
[0002]
[Prior art]
Conventional image forming apparatuses can supply power to all parts involved in image formation while the main switch (power switch) is set to ON, and can immediately form an image according to an instruction. Was kept in standby mode. However, this is not a preferable control method from the viewpoint of reducing power consumption. In view of this, a power saving mode is provided in which power supply to parts that consume a large amount of power, including parts involved in image formation, is stopped to reduce power consumption. Automatically switch to the power saving mode.
[0003]
In recent years, in order to enhance convenience while reducing power consumption, a function of automatically switching between a standby mode and a power saving mode according to a schedule determined based on the possibility of using the apparatus has been proposed. It has also been done. Since the time periods when the device is likely to be used differ depending on the user, and even the same user varies depending on the day of the week, the switching time between the standby mode and the power saving mode can be arbitrarily set by the user for each day of the week To be able to For the switching, a real time clock (RTC) for outputting the real time is provided.
[0004]
The image forming apparatus is provided with a control unit including a CPU for controlling the operation of each unit of the apparatus including image formation, and switching between a standby mode and a power saving mode is performed by a control unit that controls the entire apparatus. Is Naturally, the power supply to the control unit is continued even in the power saving mode.
[0005]
The RTC has a built-in battery and can always output real time. The CPU of the control unit that controls the operation of the entire apparatus needs to be configured with many systems because the control is complicated and diversified. In such an apparatus, a second CPU is provided in order to share complicated work between the two CPUs in terms of cost and performance.
[0006]
In such a configuration, switching from the standby mode to the power saving mode and switching from the power saving mode to the standby mode are performed by the first CPU of the control unit by the real time given by the RTC via the second CPU. It will be performed based on.
[0007]
[Problems to be solved by the invention]
However, since the second CPU that supplies the output of the RTC to the first CPU also consumes power, when the timing of switching from the power saving mode to the standby mode is always determined based on the actual time, the power saving mode may be changed. Thus, the effect of reducing the power consumption by providing the power supply cannot always be sufficiently obtained. To avoid this inconvenience, the power supply to the second CPU may be stopped in the power saving mode, and the power supply to the second CPU may be restarted immediately before switching to the standby mode.
[0008]
However, depending on the CPU, operation when power supply is cut off becomes unstable. If the second CPU is such, there is a possibility that the erroneous real time is given to the first CPU when switching to the power saving mode, and the first CPU is not switched to the power saving mode. There is. If such a situation occurs, the significance of providing the power saving mode is lost.
[0009]
Further, there is another CPU that stops power supply in the power saving mode, and if an unexpected signal is given from the CPU to the first CPU at the time of switching to the power saving mode, the control other than the mode switching can be performed by the first CPU. One CPU may malfunction.
[0010]
The present invention has been made in view of such a problem, and has as its object to prevent a malfunction in an image forming apparatus having two CPUs and stopping power supply to one of the CPUs in a power saving mode.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, power is supplied to all parts involved in image formation, and a standby mode in which an image can be formed immediately is provided. A first CPU that switches between the standby mode and the power-saving mode, in which the power-saving mode is in a state where power consumption is lower than in the standby mode, and power is supplied even in the power-saving mode; In the image forming apparatus including the second CPU that supplies a predetermined signal to the first CPU in the standby mode in which the power supply is stopped, the first CPU switches the standby mode to the power saving mode before switching to the power saving mode. The second CPU has a stop function for notifying that the switching is to be performed, and the second CPU has a stop function for stopping its own operation, and executes the stop function when notified from the first CPU. .
[0012]
After executing the stop function, the second CPU included in the image forming apparatus stops the operation until the power supply is stopped and restarted. Therefore, by notifying the switching to the power saving mode from the first CPU to the second CPU in advance and stopping the second CPU, the switching from the second CPU to the first CPU is performed at the time of switching to the power saving mode. This can eliminate the possibility that an unexpected signal is given to the CPU of the first CPU and the first CPU malfunctions.
[0013]
Here, a timer that operates by a built-in battery and outputs an actual time and a memory that is supplied with power even in a power saving mode and stores a switching time between a standby mode and a power saving mode are provided. The second CPU switches between the standby mode and the power saving mode according to the stored switching time, and the second CPU gives the first CPU the actual time output by the timer for switching from the standby mode to the power saving mode. can do. By doing so, the device automatically switches between the standby mode and the power saving mode, and it is possible to achieve both reduction in power consumption and high convenience.
[0014]
In this case, the memory may store the switching time between the standby mode and the power saving mode on each day of the week.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a digital copying machine which is an embodiment of the image forming apparatus of the present invention will be described with reference to the drawings. FIG. 1 schematically shows the entire configuration of a copying machine 1 according to the present embodiment. The copying machine 1 includes a main unit 2 that forms an image on a sheet, and a finisher unit 3 that performs predetermined post-processing on the sheet on which the image is formed and discharges the sheet.
[0016]
The main unit 2 includes a forming unit 10 that forms an image on a sheet, a supply unit 20 that supplies the sheet to the forming unit 10, a reading unit 30 that reads a document image, and a transfer unit that transfers the sheet on which the image is formed to the finisher unit 3. 40, and an operation / display unit 50 that is operated by a user and displays information.
[0017]
The forming unit 10 includes a photosensitive drum 11, a charging unit 12 for charging the photosensitive drum 11, and an exposure for irradiating the charged photosensitive drum 11 with light to partially remove electricity and form a latent image on the photosensitive drum 11. Unit 13, a developing unit 14 for applying toner to the photosensitive drum 11 on which the latent image is formed and developing the toner, a transfer unit 15 for transferring the developed image (toner) of the photosensitive drum 11 to a supplied sheet, and transfer It comprises a charge removing section 16 for removing remaining toner from the photoreceptor drum 11 and removing charges, and a fixing section 17 for fixing the image on the sheet by pressing while heating.
[0018]
The supply unit 20 includes a plurality of paper feed trays 21 and a plurality of transport rollers 20a. The reading unit 30 includes a scanner 31 and an original feeder (ADF) 32 for sequentially transporting an original to the scanner 31. The scanner 31 outputs the read image as digital image data. The transfer section 40 includes a plurality of transport rollers 40a.
[0019]
The finisher unit 3 includes a punch unit 60 for punching holes for later binding, a stapler unit 70 for binding a plurality of sheets by staples, a sorting unit 80 for separating sheets, a transport roller 3a, and a stapler unit 70 for binding sheets. An intermediate tray 3b on which sheets are placed is provided. The punch unit 60 and the stapler unit 70 operate only when an instruction is given via the operation / display unit 50.
[0020]
The sorting unit 80 includes a plurality of trays 81 that receive sheets. The trays 81 are arranged side by side up and down, and can be moved up and down. The sheet is sorted by moving the tray 81 and switching the tray 81 located at the end of the sheet transfer path by the transport roller 3a. The finisher unit 3 is detachable from the main unit 2. When the finisher unit 3 is not mounted, the sheet transferred by the transfer unit 40 is directly discharged from the main unit 2.
[0021]
Although not shown, the copier 1 includes, in the main unit 2, a motor for driving the photosensitive drum 11, the fixing roller of the fixing unit 17, and each transport roller, and a transmission mechanism for transmitting the driving force. Have. Further, a motor for moving the tray 81 and a motor for driving the punch unit 60 and the stapler unit 70 are provided in the finisher unit 3.
[0022]
FIG. 2 schematically shows a circuit configuration of the copying machine 1. Among the above-described units, the scanner 31 includes an illumination optical system 31a that illuminates the original image, and a CCD line sensor 31b that reads the illuminated original image. The operation / display unit 50 includes a plurality of keys 51 including a numeric keypad, a liquid crystal display 52, and a light emitting diode (LED) lamp 53. The key 51 is operated by a user to give an instruction to the copying machine 1. The liquid crystal display 52 displays characters and graphics to inform the user of the state of the copying machine 1 and to guide the operation. The LED lamp 53 indicates the state of the copying machine 1 depending on whether it is turned on or off. The forming unit 10 includes a laser scanning system 13 a as a part of the exposure unit 13, and includes a heater 17 a as a part of the fixing unit 17.
[0023]
The copying machine 1 also supplies power to a hard disk drive (HDD) 90 having a hard disk for storing image data, a control unit 100 for controlling the operation of the entire apparatus including image formation, and various units that operate with power. The power supply unit 110 is provided.
[0024]
The control unit 100 includes a data copy unit 101, a first CPU 102, a second CPU 103, a memory 104, an RTC 105, a clock circuit 106, and an interface (I / F) 107. The data copy unit 101 processes image data representing an image. Specifically, the image data provided from the scanner 31 is stored in the hard disk of the HDD 90, the image data is read from the hard disk, the read image data is appropriately processed, and a laser scanning system is performed based on the processed image data. 13a is controlled.
[0025]
The first CPU 102 controls the overall operation of the copying machine 1 including a part of the process related to image formation. For example, the operation of the charging unit 12, the developing unit 14, the fixing unit 17 and the like of the forming unit 10, the supply of the sheet by the supply unit 20, the reading of the image by the reading unit 30, and the transfer of the sheet by the transfer unit 30 are controlled. The CPU 102 also controls the operations of the punch unit 60, the stapler unit 70, and the sorting unit 80 of the finisher unit 3, and controls the power supply from the power supply unit 110.
[0026]
The second CPU 103 gives the first CPU 102 a signal indicating the actual time output from the RTC 105. The RTC 105 has a built-in battery, operates by its power, and constantly outputs a signal indicating the actual time. The clock circuit 106 has a built-in oscillator, and outputs a clock signal used by the first and second CPUs 102 and 103 as a reference for operation timing.
[0027]
The memory 104 includes a ROM that stores a program describing the control of the first CPU 102 and a RAM that temporarily stores parameters used by the CPU 102 for control. The ROM also includes a rewritable flash memory, and the flash memory describes parameters that can be changed by a user.
[0028]
The copier 1 supplies electric power to all the parts, and a standby mode in which an image can be formed immediately in response to an instruction from a user. It has a power saving mode with low power consumption. The power supply line from the power supply unit 110 is divided into two systems as shown in FIG. In the standby mode, power is supplied from both the power supply line A without hatching and the power supply line B with hatching, and in the power saving mode, power supply from the power supply line B is stopped. .
[0029]
The portions connected to the power supply line A to which power is constantly supplied include the operation keys 51 and the LED lamp 53 of the operation / display unit 50, and the first CPU 102, the memory 104, and the clock 106 of the control unit 100. . In addition, at a portion connected to the power supply line B and stopping power supply in the power saving mode, the forming unit 10, the supply unit 20, the reading unit 30, the transfer unit 40, the liquid crystal display 52 of the operation / display unit 50, The entire finisher unit 3, the HDD 90, and the second CPU 103 of the control unit 100 are included.
[0030]
The copying machine 1 has a function of automatically switching from a standby mode to a power saving mode when a state in which image formation is not performed has continued for a predetermined time in order to reduce power consumption. In this case, the release of the power saving mode, that is, the return to the standby mode is instructed by operating the predetermined operation key 51. Switching between the standby mode and the power saving mode is performed by the first CPU 102.
[0031]
The copying machine 1 also has a function of storing the switching time between the standby mode and the power saving mode for each day of the week, and switching between the standby mode and the power saving mode according to the stored time. The switching time from the standby mode to the power saving mode and the switching time from the power saving mode to the standby mode are stored in the flash memory of the ROM of the memory 104 and can be changed by the user. This switching is also performed by the first CPU 102.
[0032]
The appearance of the display / operation unit 50 is shown in FIG. As described above, the display / operation unit 50 is provided with the key 51, the liquid crystal display 52, and the LED lamp 53. The keys 51 include a numeric keypad 51a for inputting numerical values of 0 to 9, a start key 51b for instructing the start of an image forming operation, and a power-saving mode cancel key 51c for instructing switching from the power-saving mode to the standby mode. ing. The LED lamp 53 includes a power lamp 53a indicating that a main switch (power switch) is on, and a power saving mode lamp 53b indicating that the camera is in a power saving mode.
[0033]
The liquid crystal display 52 displays information on image formation and overall operation. FIG. 3 shows an example of a state in the standby mode. The liquid crystal display 52 displays a state in which an original image can be read and the image can be formed on a sheet, and three copies of the same image are formed. In addition to the information indicating that the image is to be formed on the sheet, the size of the image to be formed, the size (magnification) of the image to be formed, and the density of the image are displayed. Also, a menu item “detailed setting” for setting and confirming the operation is displayed. The liquid crystal display 52 is configured as a touch panel that detects a pressed portion, and the user can specify the item by pressing the displayed portion.
[0034]
In the state of FIG. 3, when the item “power management” is specified by the user, the display on the liquid crystal display 52 is changed, and the time until switching to the power saving mode when image formation is not performed is set. A screen for setting or a screen for setting a switching time between the standby mode and the power saving mode for each day of the week is displayed.
[0035]
FIG. 4 shows an example of a screen for setting the switching time between the standby mode and the power saving mode for each day of the week. For each day of the week, an “ON time” for switching from the power saving mode to the standby mode and an “OFF time” for switching from the standby mode to the power saving mode are displayed. These times can be changed by operating the items displayed on the right side. It is also possible not to set the time. In the example of FIG. 4, neither “ON time” nor “OFF time” is set for Saturday and Sunday. In this case, the power saving mode is maintained all day on Saturday and Sunday.
[0036]
As described above, the switching between the standby mode and the power saving mode is performed by the first CPU 102, and the CPU 102 uses the actual time output by the RTC 105 to determine the switching time. Here, the output of the RTC 105 is given to the first CPU 102 via the second CPU 103, but since the second CPU 103 is supplied with power from the power supply line B, the power is supplied over the entire period of the power saving mode. When the power supply from the line B is stopped, the first CPU 102 cannot use the real time output by the RTC 105 to determine the timing of switching from the power saving mode to the standby mode.
[0037]
Therefore, in the copying machine 1, a mode in which power is supplied from both the power supply line A and the power supply line B in addition to a mode in which power is supplied only from the power supply line A is set in the power saving mode. The power supply from the power supply line B is started before switching to the standby mode. Hereinafter, a mode in which power is supplied from both the power supply line A and the power supply line B is referred to as a first mode, and a mode in which power is supplied only from the power supply line A is referred to as a second mode.
[0038]
When the copying machine 1 is in the standby mode, the first CPU 102 switches the power saving mode when the actual time given from the second CPU 103 reaches the switching time to the power saving mode stored in the memory 104. Switch to the second mode. At this time, the actual time of the switching is stored in the memory 104.
[0039]
When the copying machine 1 is in the second mode of the power saving mode, the first CPU 102 counts a clock signal from the clock circuit 106 to measure an elapsed time in the power saving mode, and stores the stored power saving mode. The time is estimated from the switching time to the mode and the elapsed time in the power saving mode, and when the estimated time reaches a predetermined time before the switching time to the standby mode, the mode is switched to the first mode. Thus, the second CPU 103 operates and the first CPU 102 can obtain the real time from the RTC 105. After switching to the first mode in this way, the first CPU 102 switches to the standby mode when the actual time given from the second CPU 103 reaches the switching time to the standby mode.
[0040]
This series of processing makes it possible to both reduce power consumption by stopping power supply to the second CPU 103 and switch from the power saving mode to the standby mode, and supply power to the second CPU 103 constantly. As in the case of switching to the standby mode, switching to the standby mode can be performed at an accurate time.
[0041]
In general, an oscillator used in a clock circuit oscillates at a constant cycle, but the cycle has a slight difference between oscillators even if the oscillator has the same standard. For this reason, the cycle of the signal output from the clock circuit also differs for each clock circuit. Therefore, the elapsed time measured by the first CPU 102 is affected by an error in the output cycle of the clock circuit 106, and an error occurs at a time when the elapsed time is estimated to be too long.
[0042]
In the copying machine 1, even if an error occurs in the estimated time, in order to ensure that the switching from the power saving mode to the standby mode can be performed, as described above, Is also switched to the first mode a predetermined time before. The predetermined time is, for example, 3 minutes. This is a value determined in consideration of the error of the oscillation cycle allowed by the standard oscillator and that the period of the power saving mode is usually about 10 hours.
[0043]
However, the period of the power saving mode may exceed 24 hours as in the example shown in FIG. 4, and in this case, the error of the estimated time may increase as the time exceeds the predetermined time. When such a situation occurs, the switching to the first mode is later than the switching time to the standby mode, and the switching to the standby mode is not performed. On the contrary, the switching to the first mode is earlier. Too much power may be wasted.
[0044]
In order to prevent such an inconvenience, the copying machine 1 temporarily switches from the second mode to the first mode at predetermined time intervals after the switching to the power saving mode, and sets the first mode. During this period, the real time from the RTC 105 is given from the second CPU 103 to the first CPU 102 so that the estimated time is corrected. Specifically, the CPU 102 stores the latest actual time in the memory 103, and newly measures the elapsed time from that point.
[0045]
The predetermined elapsed time is, for example, 24 hours. This is a value determined in consideration of the error of the oscillation period allowed in the standard oscillator and the above-described predetermined time for switching to the first mode earlier than switching to the standby mode. . Note that the length of the period of the standby mode for temporarily switching need only be sufficient to give the real time to the first CPU 102 after the second CPU 103 starts operating, and is extremely short. The power consumption is hardly increased by temporarily switching to the standby mode.
[0046]
FIG. 5 shows a flow of processing in which the first CPU 102 switches between the standby mode and the power saving mode according to the stored time. This process starts when the camera is in the standby mode.
[0047]
First, the real time Ta output by the RTC 105 from the second CPU 103 is obtained (# 105), and it is determined whether or not the real time Ta is the off time Ts to be switched to the power saving mode. If not, the process waits (step # 110). When the real time Ta becomes the off time Ts, each unit other than the control unit 100 is set to a non-operation state (# 115), and the real time Ta is stored in the memory 104 as the actual switching time Tc to the second mode. (# 120). Further, a predetermined time ti (for example, the above-described 24 hours) is added to the actual time Ta, and the obtained time is stored in the memory 104 as the time Tu for which the calculated time is to be corrected (# 125). Next, the second CPU 103 is stopped (# 130), the power supply from the power supply line B is stopped, and the mode is switched to the second power saving mode (# 135).
[0048]
After switching to the second mode, the first CPU 102 counts the elapsed time from the output signal of the clock circuit 106, and calculates the current time T0 from this and the time Tc stored in step # 120 (# 140). . Then, it is determined whether or not the calculated time T0 is a predetermined time tb (for example, the above-described three minutes) before the on-time Tw to be switched to the standby mode (# 145), and it must be before the predetermined time tb. For example, it is determined whether or not the calculated time T0 is the time Tu stored in step # 125 (# 150). If the time T0 has reached the time Tu, a process of correcting the calculated time T0 is performed (# 155). If the time T0 has not reached the time Tu, the process returns to step # 140 without performing the process.
[0049]
If it is determined in step # 145 that the calculated time T0 is a predetermined time tb before the time Tw, power is also supplied from the power supply line B to switch to the first mode (# 160). Then, the real time Ta output by the RTC 105 from the second CPU 103 is acquired (# 165), and the real time Ta becomes the on time Tw until the real time Ta becomes the on time Tw (# 170). At this point, the mode is switched to the standby mode (# 175).
[0050]
FIG. 6 shows the flow of the correction process at the calculated time T0 in step # 155. First, power is also supplied from the power supply line B to switch to the first mode (step # 205). Next, the real time Ta is obtained from the second CPU 103 (# 210), and this is stored in the memory 104 as the actual switching time Tc to the second mode (# 215). And the obtained time is stored in the memory 104 as the time Tu at which the calculated time T0 is to be corrected (# 220). Then, the second CPU is stopped (# 225), the power supply from the power supply line B is stopped, and the mode is switched to the second mode (# 230).
[0051]
FIG. 7 shows the flow of the process of calculating the current time T0 in step # 140 and the process of obtaining the real time Ta in steps # 105 and # 165. First, it waits for one second to elapse based on the output signal of the clock circuit 106 (step # 305), and determines whether the mode is the second mode or the first mode (# 310). In the second mode, one second is added to the current time T0 (# 315), and in the first mode, the real time Ta is obtained from the second CPU 103 (# 320).
[0052]
In the copying machine 1 of the present embodiment, as the second CPU 103 that gives the real time output from the RTC 105 to the first CPU 102, a second CPU 103 having a stop function of stopping its own operation while receiving power supply is used. . Then, as performed in step # 130 of FIG. 5 and step # 225 of FIG. 6, before switching from the first mode to the second mode, that is, while supplying power to the second CPU 103, The operation of the second CPU 103 is stopped by causing the second CPU 103 to execute the stop function.
[0053]
This is because the operation of the CPU when power supply is cut off becomes unstable depending on the CPU, and if the second CPU 103 is of such a type, the first CPU 102 switches to the second mode when switching to the second mode. This is because there is a possibility that an erroneous real time is given and the first CPU 102 does not switch to the power saving mode. If the second CPU 103 is stopped at the time of switching to the second mode, no signal including the erroneous actual time is given to the first CPU 102.
[0054]
FIGS. 8 and 9 show the flow of the stop processing of the second CPU 103 in step # 130 and step # 225. FIG. 8 shows a process performed by the first CPU 102, and FIG. 9 shows a process performed by the second CPU 103.
[0055]
As shown in FIG. 8, first CPU 102 first notifies second CPU 103 that preparations should be made in preparation for switching to the second mode (step # 405). Then, the process waits for the completion of the preparation to be notified from the second CPU 103 (# 410). If the completion of the preparation is notified, the second CPU 103 is notified to stop the operation (# 415). ). Then, it waits for another 10 milliseconds to elapse (# 420). After that, in step # 135 or # 230, the power supply to the second CPU 103 is stopped.
[0056]
As shown in FIG. 9, the second CPU 103 repeatedly determines whether or not there is a notification from the first CPU 102 (step # 505). Then, when there is a notification, it is determined whether or not it is an instruction for preparation (# 510). If it is an instruction for preparation, the operation of its own predetermined part is stopped (# 515). ), The completion of the preparation is notified to the first CPU 102 (# 520), and the process returns to step # 505. If the notification does not instruct the preparation, it is determined whether or not the stop is instructed (# 525). If not, the process returns to step # 505. If the notification is a stop instruction, the operation of all the parts is stopped (# 530). Thereafter, when the power supply is stopped and restarted, the second CPU 103 performs its own initialization processing and starts a normal operation.
[0057]
In the present embodiment, an example in which the switching time from the standby mode to the power saving mode and the switching time from the power saving mode to the standby mode are stored once a day has been described. A plurality of mode switching times may be stored in one day. By doing so, for example, it is possible to set the power saving mode at night and during lunch break, and it is possible to further reduce power consumption. In that case, the predetermined time for switching from the second mode to the first mode earlier than switching to the standby mode can be shorter than the illustrated three minutes.
[0058]
Further, a control having a stop function is used as the second CPU, and the control of stopping the operation of the second CPU before stopping the power supply to the second CPU is not limited to the processing of the time. It is applicable when the CPU is used for any other processing. Although a copying machine has been described as an image forming apparatus of the present invention, the present invention can be applied to other image forming apparatuses such as a facsimile and a printer.
[0059]
【The invention's effect】
Power is supplied to all parts involved in image formation, and a standby mode in which an image can be formed immediately, and power supply to a predetermined part is stopped, so that power consumption is lower than in the standby mode. A first CPU that has a power saving mode in a small state, in which power is supplied even in the power saving mode, and switches between the standby mode and the power saving mode; In an image forming apparatus including a second CPU that supplies a predetermined signal to one CPU, as in the present invention, the first CPU switches to the second CPU before switching from the standby mode to the power saving mode. If the second CPU has a stop function for notifying that the operation is to be performed and the second CPU stops its own operation, and executes the stop function when notified from the first CPU, the power saving mode is achieved. Upon switching to, the second CPU unexpected by signals applied to the first CPU, the first CPU is able to eliminate the possibility of malfunction.
[0060]
A timer that operates by a built-in battery and outputs an actual time; and a memory that is supplied with power even in a power saving mode and stores a switching time between a standby mode and a power saving mode. When the second CPU switches between the standby mode and the power saving mode according to the switching time, and the second CPU gives the first CPU an actual time output by the timer for switching from the standby mode to the power saving mode, The device automatically switches between the power saving mode and the power saving mode, so that the power consumption can be reliably reduced, and when the user wants to use the device, the device can be used immediately, which is highly convenient.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating an overall configuration of a digital copying machine according to an embodiment of the invention.
FIG. 2 is a block diagram schematically showing a circuit configuration of the copying machine.
FIG. 3 is a diagram showing an example of the appearance of a display / operation unit of the copying machine.
FIG. 4 is a view showing an example of a display screen for setting a switching time between a standby mode and a power saving mode for each day of the week in the copying machine.
FIG. 5 is a flowchart showing a flow of a process in which a first CPU of the copying machine switches between a standby mode and a power saving mode in accordance with a stored time.
FIG. 6 is a flowchart showing the flow of a process of correcting the calculated time in step # 155 of FIG. 5;
7 is a flowchart showing a flow of a current time calculation process in step # 140 of FIG. 5 and a real time acquisition process in steps # 105 and # 165.
FIG. 8 is a flowchart showing the flow of stop processing of the second CPU in step # 130 of FIG. 5 and step # 225 of FIG. 6;
FIG. 9 is a flowchart showing the flow of a process performed by a second CPU corresponding to the process of FIG. 8;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Digital copying machine 2 Main unit 3 Finisher unit 3a Conveyor roller 3b Intermediate tray 10 Forming unit 11 Photoconductor drum 12 Charging unit 13 Exposure unit 13a Laser scanning system 14 Developing unit 15 Transfer unit 16 Static elimination unit 17 Fixing unit 17a Heater 20 Supply unit 20a transport roller 21 paper feed tray 30 reading unit 31 scanner 31a illumination optical system 31b CCD line sensor 32 original feeder 40 transport unit 40a transport roller 50 operation / display unit 51 operation keys 51a ten-key 51b start key 51c power saving mode release key 52 liquid crystal Indicator 53 LED lamp 53a Power lamp 53b Power saving mode lamp 60 Punch unit 70 Stapler unit 80 Separation unit 81 Tray 90 Hard disk drive 100 Control unit 101 Data copy unit 102 First C U
103 Second CPU
104 memory 105 RTC (real time clock)
106 Clock circuit 107 Interface

Claims (3)

Power is supplied to all parts involved in image formation, and a standby mode in which an image can be formed immediately, and power supply to a predetermined part is stopped, so that power consumption is lower than in the standby mode. A first CPU that has a power saving mode in a small state, in which power is supplied even in the power saving mode, and switches between the standby mode and the power saving mode; In an image forming apparatus including a second CPU that supplies a predetermined signal to one CPU,
Before the first CPU switches from the standby mode to the power saving mode, the first CPU notifies the second CPU to switch.
An image forming apparatus, wherein the second CPU has a stop function for stopping its own operation, and executes the stop function when notified by the first CPU. A timer that operates with a built-in battery and outputs the actual time;
Power is supplied even in the power saving mode, and a memory storing the switching time of the standby mode and the power saving mode is provided,
The first CPU switches between the standby mode and the power saving mode according to the switching time stored in the memory,
2. The image forming apparatus according to claim 1, wherein the second CPU gives the first CPU an actual time output by the timer for switching from the standby mode to the power saving mode. 3. The image forming apparatus according to claim 2, wherein the memory stores a switching time between the standby mode and the power saving mode on each day of the week.

Images