Patent Description:
An image forming apparatus that can shift to a power saving state when print and scan functions are not being executed has been known. In the power saving state, power supply to a printer unit and a scanner unit (hereinafter, when appropriate, referred to for short as a printer unit and the like) for executing the functions is stopped. If the image forming apparatus is in the power saving state and a return factor is detected, power is supplied to the printer unit and the scanner unit. Examples of the return factor include pressing of a return button by a user.

Even if a return factor is detected, the printer unit and the like are not necessarily used. For example, when image data of a scanned document is stored into a memory of the image forming apparatus, power does not need to be supplied to the printer unit. In other words, if power is supplied to all the devices upon detecting a return factor, even unnecessary devices may be powered on.

A technique for performing control so that power is supplied to a device or devices that execute(s) the function to be used and not to a device or devices that execute(s) unused functions has been discussed in <CIT>.

An image forming apparatus discussed in <CIT> determines which device(s) to supply power to according to a factor for canceling a power saving state. More specifically, according to <CIT>, if a print request signal is received from an external apparatus, power is supplied to a printer unit to perform printing, and not to a scanner unit. If a sensor detects that a document is placed on the scanner unit, power is supplied to the scanner unit and not to the printer unit.

According to <CIT> described above, no power is supplied to the printer unit and the like unless the printer unit and the like are determined to be used. More specifically, when a return button arranged on an operation unit is pressed, it is not yet determined whether to use the print and/or scan function(s). No power is thus supplied to the printer unit and the like. When the print and/or scan function(s) is/are subsequently determined to be used, power is supplied to the device(s) needed to perform the function(s) (see paragraph <NUM> of <CIT>). In other words, according to <CIT>, no power is supplied to the printer unit and the like until the print and/or scan function(s) is/are determined to be used. The user therefore needs to wait until the power to the printer unit and/or the scanner unit stabilizes, while the printer unit and/or the scanner unit is/are reset, and while a preparation operation of the printer unit and/or the scanner unit (driving of the driving systems (motors)) is performed.

On the other hand, suppose that the preparation operation of the printer unit and the like is performed before it is determined whether to use the print and/or scan function(s). In such a case, the preparation operation can consume useless power unless the printer unit and the like are used. There is another disadvantage that the preparation operation of the devices produces noise if the printer unit and the like are not used.

<CIT> discusses a power-supply control device includes a power-supply-state transition control section, body-capable-of-movement detection sections, and an instruction section. The power-supply-state transition control section shifts a state of an operation target section from one state to another state among power-supply states and a non-power-supply state. The body-capable-of-movement detection sections detect a body capable of movement in a region. The instruction section provides, on the basis of results of detection of the body capable of movement by the body-capable-of-movement detection sections, at least an instruction for shifting between one of the power-supply states and the non-power-supply state, among instructions for shifting the state of the operation target section from one state to another state with the power-supply-state transition control section.

The present invention is directed to an image forming apparatus capable of preventing useless consumption of power and generation of noise by a preparation operation of a printer unit and the like when the image forming apparatus returns from a power saving state, and further capable of reducing time for the functions of the printer unit and the like to become usable when the printer unit and the like are determined to be used by supplying power to the printer unit and the like before the printer unit and the like are determined to be used.

According to a first aspect of the present invention, there is provided an image forming apparatus as specified in claims <NUM> to <NUM>. According to a second aspect of the present invention, there is provided a control method of controlling an image forming apparatus as specified in clam <NUM>.

Various exemplary embodiments, features, and aspects of the invention will be described in detail below with reference to the drawings.

<FIG> is a diagram illustrating a structure of an image forming apparatus according to a first exemplary embodiment of the present invention.

As illustrated in <FIG>, an image forming apparatus <NUM> includes a scanner unit <NUM> serving as an image input device and a printer unit <NUM> serving as an image output device.

The scanner unit <NUM> is a device for reading an image formed on a document to obtain image data. The scanner unit <NUM> irradiates the image formed on the document with light and inputs reflected light into a charge-coupled device (CCD) sensor to convert information about the image into an electrical signal. The electrical signal is converted into luminance signals of respective colors of red (R), green (G), and blue (B), and output to a controller <NUM> to be described below.

Documents set on a tray <NUM> of the scanner unit <NUM> are fed to a reading position of an optical unit <NUM> on a platen glass <NUM> one by one by a document feeder <NUM>. The document read by the optical unit <NUM> is discharged to a discharge tray <NUM>. Light emitted from the lamp <NUM> of the optical unit <NUM> and reflected by the document is input to a CCD image sensor <NUM> via mirrors <NUM>, <NUM>, and <NUM> and a lens <NUM>. Documents may be read by other methods than the automatic feeding method using the document feeder <NUM>. In one possible method, a carriage on which the optical unit <NUM> is mounted may scan over a document placed on the platen glass <NUM>. The first exemplary embodiment deals with the image forming apparatus <NUM> that is capable of monochromatic printing, whereas the image forming apparatus <NUM> may be capable of color printing.

The printer unit <NUM> is a device for forming an image on a sheet by using input image data. The printer unit <NUM> according to the present exemplary embodiment is an electrophotographic printer unit using a photosensitive drum or a photosensitive belt. However, an exemplary embodiment of the present invention is not limited thereto. For example, the printer unit <NUM> may be an inkjet printer unit that performs printing on a sheet by discharging ink from a minute nozzle array.

The image forming apparatus <NUM> further includes a plurality of sheet cassettes <NUM>, <NUM>, <NUM>, and <NUM>, and a manual feed tray <NUM>. The plurality of sheet cassettes <NUM>, <NUM>, <NUM>, and <NUM> store sheets for the printer unit <NUM> to form an image thereon. A laser driver <NUM> of the printer unit <NUM> drives a laser emitting unit <NUM>. The laser driver <NUM> causes the laser emitting unit <NUM> to emit laser light according to image data output from the controller <NUM>. A photosensitive drum <NUM> is irradiated with the laser light, whereby a latent image according to the laser light is formed on the photosensitive drum <NUM>. A developing device <NUM> applies a developer to the latent image portions of the photosensitive drum <NUM>. A transfer unit <NUM> transfers the developer applied to the photosensitive drum <NUM> to recording paper passed through a conveyance path <NUM>. The recording paper bearing the developer is conveyed to a fixing device <NUM> by a conveyance belt <NUM>. The fixing device <NUM> fixes the developer onto the recording paper by heat and pressure. The recording paper having passed through the fixing device <NUM> passes through conveyance paths <NUM> and <NUM>, and discharged to a sheet discharge tray <NUM>. If the recording paper is to be discharged to the sheet discharge tray <NUM> with the printed side reversed, the recording paper is guided into conveyance paths <NUM> and <NUM> before passing through a conveyance path <NUM> and the conveyance path <NUM>.

For two-sided printing, the recording paper is guided from the fixing device <NUM> to the conveyance path <NUM> and then guided by a flapper <NUM> to a conveyance path <NUM>. The recording paper is then conveyed in a reverse direction and guided by the flapper <NUM> to the conveyance path <NUM> and a re-feed conveyance path <NUM>. The recording paper guided into the re-feed conveyance path <NUM> passes through the conveyance path <NUM>, and fed to the transfer unit <NUM>.

<FIG> is a diagram illustrating details of an operation unit. The image forming apparatus <NUM> includes an operation unit <NUM>. As illustrated in <FIG>, the operation unit <NUM> includes various buttons <NUM> to be operated by the user, and a display unit <NUM> for displaying images. A touch panel is arranged on the surface of the display unit <NUM>. The display unit <NUM> displays a status screen for displaying a status of the image forming apparatus <NUM>, a selection screen for selecting a copy function and a facsimile (FAX) function, and a setting screen for inputting information needed to execute the function selected from the selection screen. On the display unit <NUM> illustrated in <FIG>, the selection screen is displayed. The buttons <NUM> include buttons 121a for inputting the number of print copies, a start button 121b for starting copying or FAX transmission, and a power saving button 121c for shifting the image forming apparatus <NUM> into a power saving state (first sleep state to be described below).

When the image forming apparatus <NUM> is activated, the selection screen is displayed on the display unit <NUM>. The selection screen includes a copy button 122a for executing the copy function, a scan button 122b for executing a scan function, a FAX button 122c for executing the FAX function, and a print button 122d for executing a print function.

<FIG> is a block diagram illustrating the controller <NUM> that controls the entire image forming apparatus <NUM>. The controller <NUM> that controls the overall operation of the image forming apparatus <NUM> will be described in detail with reference to <FIG>.

As illustrated in <FIG>, the controller <NUM> is electrically connected to the scanner unit <NUM>, the printer unit <NUM>, and the operation unit <NUM> described above. The controller <NUM> includes a central processing unit (CPU) <NUM>, a random access memory (RAM) <NUM>, a read-only memory (ROM) <NUM>, an operation unit interface (I/F) <NUM>, a local area network (LAN) controller <NUM>, a human body detection sensor <NUM>, a sheet detection sensor <NUM>, and a power supply control unit <NUM>. The CPU <NUM>, the RAM <NUM>, the ROM <NUM>, the operation unit I/F <NUM>, the LAN controller <NUM>, the human body detection sensor <NUM>, the sheet detection sensor <NUM>, and the power supply control unit <NUM> are connected to a system bus <NUM>. The controller <NUM> further includes a hard disk drive (HDD) <NUM>, an image processing unit <NUM>, a scanner I/F <NUM>, and a printer I/F <NUM>. The HDD <NUM>, the image processing unit <NUM>, the scanner I/F <NUM>, and the printer I/F <NUM> are connected to an image bus <NUM>.

The CPU <NUM> controls access to various connected devices in a comprehensive manner based on a control program stored in the ROM <NUM>. The CPU <NUM> also controls various types of processing executed by the controller <NUM> in a comprehensive manner.

The RAM <NUM> is a system work memory for the CPU <NUM> to operate with. The RAM <NUM> also serves as a memory for temporarily storing image data. The RAM <NUM> includes a static random access memory (SRAM) which can retain stored contents even when powered off, and a dynamic random access memory (DRAM) in which stored data is erased when powered off. The ROM <NUM> stores a boot program of the image forming apparatus <NUM>. The HDD <NUM> stores a program for controlling the image forming apparatus <NUM> and image data.

The operation unit I/F <NUM> is an interface unit for connecting the system bus <NUM> and the operation unit <NUM>. The operation unit I/F <NUM> receives image data to be displayed on the operation unit <NUM> from the system bus <NUM>, and outputs the image data to the operation unit <NUM>. The operation unit I/F <NUM> outputs information input from the operation unit <NUM> to the system bus <NUM>.

The LAN controller <NUM> controls input and output of information between the image forming apparatus <NUM> and an external apparatus <NUM> connected to a network <NUM>.

The human body detection sensor <NUM> is an infrared sensor array in which infrared sensors for receiving infrared rays are arranged in a matrix manner. The human body detection sensor <NUM> detects the approach of a person to the image forming apparatus <NUM> by receiving infrared rays radiated from the person. While the present exemplary embodiment deals with an example where the human body detection sensor <NUM> detects a person, the human body detection sensor <NUM> can detect any object that radiates infrared rays. Note that the human body detection sensor <NUM> is not limited to the infrared sensor. Sensors other than an infrared sensor may be used as long as the sensors can detect the approach of an object to the image forming apparatus <NUM>. Examples of sensors include an optical sensor which detects light, a distortion sensor which deforms under physical force, a magnetic sensor which detects magnetism, and a temperature sensor which detects temperature.

The sheet detection sensor <NUM> detects that a sheet is set on the manual feed tray <NUM>.

The power supply control unit <NUM> controls power supply to the components in the image forming apparatus <NUM>. The power supply control unit <NUM> will be described in detail below.

The image bus <NUM> is a transmission path for exchanging image data. Examples of the image bus <NUM> include a peripheral component interface (PCI) bus and an Institute of Electrical and Electronics Engineers (IEEE) <NUM> bus.

The image processing unit <NUM> is for image processing. The image processing unit <NUM> reads image data stored in the RAM <NUM> and performs image processing. Examples of the image processing include enlargement and reduction of Joint Photographic Expert Group (JPEG) and Joint Bi-level Image Experts Group (JBIG) images, and color adjustment.

The scanner unit <NUM> includes a scanner control unit <NUM> and a scanner drive unit <NUM>. The scanner drive unit <NUM> is a physically-driving device that includes a paper conveying motor for conveying a document set on the tray <NUM> to the reading position of the scanner unit <NUM>. The scanner control unit <NUM> controls an operation of the scanner drive unit <NUM>. The scanner control unit <NUM> receives setting information through communication with the CPU <NUM> and controls the operation of the scanner drive unit <NUM> based on the setting information. The setting information is set by the user when performing scanner processing.

The printer unit <NUM> includes a printer control unit <NUM> and a printer drive unit <NUM>. The printer drive unit <NUM> is a physically-driving device that includes a motor for rotating the photosensitive drum <NUM>, a motor for rotating the fixing device <NUM>, and a paper conveyance motor. The printer control unit <NUM> controls an operation of the printer drive unit <NUM>. The printer control unit <NUM> receives setting information through communication with the CPU <NUM> and controls the operation of the printer drive unit <NUM> based on the setting information. The setting information is set by the user when performing print processing.

<FIG> is a power supply circuit diagram of the image forming apparatus <NUM>. Power generated by the power unit <NUM> is supplied to the components of the image forming apparatus <NUM> described above. The power unit <NUM> includes a first power supply unit <NUM>, a second power supply unit <NUM>, and a third power supply unit <NUM>.

The first power supply unit <NUM> converts alternative-current power supplied through a plug P into direct-current power (e.g., <NUM> V (first output power)). The direct-current power is supplied to devices of a first power supply system (the power supply control unit <NUM>, the CPU <NUM>, the RAM <NUM>, the ROM <NUM>, the HDD <NUM>, the LAN controller <NUM>, the human body detection sensor <NUM>, the sheet detection sensor <NUM>, and the buttons <NUM> of the operation unit <NUM>). In the present exemplary embodiment, the CPU <NUM> operates only with the power supplied from the first power supply unit <NUM>, without receiving power supply from the second power supply unit <NUM> or the third power supply unit <NUM>. In other words, the power supply of the CPU <NUM> is independent from the second power supply unit <NUM> and the third power supply unit <NUM>. The second power supply unit <NUM> converts the alternating-current power supplied through the plug P into direct-current power (e.g., <NUM> V (second output power)). This direct-current power is supplied to devices of a second power supply system (the display unit <NUM> of the operation unit <NUM>, the image processing unit <NUM>, the printer control unit <NUM> of the printer unit <NUM>, and the scanner control unit <NUM> of the scanner unit <NUM>). The third power supply unit <NUM> converts the alternating-current power supplied through the plug P into direct-current power (e.g., <NUM> V), and supplies the direct-current power to devices of a third power supply system (the printer drive unit <NUM> and the scanner drive unit <NUM>).

A power switch <NUM> is arranged between the first power supply unit <NUM> and the devices of the first power supply system. The power switch <NUM> becomes an ON state or an OFF state according to the user's operation. A signal D indicating the state of the power switch <NUM> (ON state or OFF state) is input to the power supply control unit <NUM>. The power unit <NUM> further includes a switch <NUM>, which is constituted with a field effect transistor (FET), arranged in parallel with the power switch <NUM>. The switch <NUM> changes from an ON state to an OFF state or from the OFF state to the ON state according to a control signal E output from the power supply control unit <NUM>. The power switch <NUM> includes a solenoid 416a. A voltage is applied to the solenoid 416a according to a control signal G output from the power supply control unit <NUM>, whereby the power switch <NUM> is changed to the OFF state. When an automatic shutdown function or a remote shutdown function of the image forming apparatus <NUM> is executed, the power supply control unit <NUM> outputs the control signal G to drive the solenoid 416a to turn off the power switch <NUM>. The automatic shutdown function is a function of shutting down the image forming apparatus <NUM> if a predetermined time elapses in a second sleep state to be described below without a user's operation. The remote shutdown function is a function of shutting down the image forming apparatus <NUM> according to a shutdown instruction transmitted from the external apparatus <NUM>.

A relay switch <NUM> is arranged between the plug P and the second power supply unit <NUM>. A relay switch <NUM> is arranged between the plug P and the third power supply unit <NUM>. The relay switches <NUM> and <NUM> change from an ON state to an OFF state or from the OFF state to the ON state according to a control signal F output from the power supply control unit <NUM>.

A switch <NUM> is arranged between the power switch <NUM> and the CPU <NUM>, ROM <NUM>, and HDD <NUM>. The switch <NUM> changes from an ON state to an OFF state or from the OFF state to the ON state according to a control signal H output from the power supply control unit <NUM>.

A switch 421a is arranged between the second power supply unit <NUM> and the printer control unit <NUM>. A switch 421b is arranged between the third power supply unit <NUM> and the printer drive unit <NUM>. The switches 421a and 421b change from an ON state to an OFF state or from the OFF state to the ON state according to a control signal J output from the power supply control unit <NUM>.

A switch 422a is arranged between the second power supply unit <NUM> and the scanner control unit <NUM>. A switch 422b is arranged between the third power supply unit <NUM> and the scanner drive unit <NUM>. The switches 422a and 422b change from an ON state to an OFF state or from the OFF state to the ON state according to a control signal K output from the power supply control unit <NUM>.

<FIG> is a power state transition diagram of the image forming apparatus <NUM>.

As illustrated in <FIG>, the image forming apparatus <NUM> takes any one of a power off state, the second sleep state, the first sleep state, a standby state, and an adjustment state. The image forming apparatus <NUM> may take other states than those described above.

If the user changes the power switch <NUM> to the OFF state, the image forming apparatus <NUM> shifts to the power off state.

In the power off state, if the user changes the power switch <NUM> to the ON state, the image forming apparatus <NUM> shifts to the standby state.

If the user presses the power saving button 121c in the standby state, the image forming apparatus <NUM> shifts to the second sleep state. If a predetermined time elapses in the standby state without the operation unit <NUM> (the touch panel and the buttons <NUM>) being operated, the image forming apparatus <NUM> shifts to the second sleep state.

In the present exemplary embodiment, if the image forming apparatus <NUM> receives a page description language (PDL) job (print request) or if the user presses the power saving button 121c in the second sleep state, the image forming apparatus <NUM> shifts to the standby state. In the second sleep state, if the human body detection sensor <NUM>, the sheet detection sensor <NUM>, or a document detection sensor <NUM> (see <FIG>) included in the scanner unit <NUM> enters a detection state (i.e., detects a corresponding object), the image forming apparatus <NUM> shifts to the standby state.

In the second sleep state, instead of the CPU <NUM> of the controller <NUM>, the LAN controller <NUM> returns a response to a specific packet transmitted from the external apparatus <NUM>. Such a function of the LAN controller <NUM> will be referred to as a proxy response. The proxy response of the LAN controller <NUM> enables the image forming apparatus <NUM> to respond to the specific packet transmitted from the external apparatus <NUM> while remaining in the second sleep state.

In the second sleep state, if the LAN controller <NUM> receives a packet to which no proxy response can be made (except a PDL job) from the external apparatus <NUM>, the image forming apparatus <NUM> shifts from the second sleep state to the first sleep state.

The image forming apparatus <NUM> having shifted to the first sleep state processes the packet to which no proxy response can be made. The image forming apparatus <NUM> then shifts to the second sleep state without waiting for the above-described predetermined time.

If a timer <NUM> (see <FIG>) included in the printer control unit <NUM> has counted a predetermined time in the second sleep state, the image forming apparatus <NUM> shifts to the adjustment state. If the image forming apparatus <NUM> performs a specific operation (such as rotating the photosensitive drum <NUM>) in the adjustment state, the image forming apparatus <NUM> shifts to the second sleep state again.

<FIG> is a table summarizing power feed states of the devices in each power state of the image forming apparatus <NUM>. <FIG> are diagrams illustrating the state of the image forming apparatus <NUM> in the respective power states. More specifically, the gray color blocks in <FIG> indicate the devices that no power is supplied thereto. The power states of the image forming apparatus <NUM> will be described with reference to <FIG>.

The power off state refers to a state where, as illustrated in <FIG> and <FIG>, no power is supplied to the components of the image forming apparatus <NUM>. In the power off state, as illustrated in <FIG>, the switches <NUM> to <NUM> are in the OFF state. The power off state may be a hibernation state. A hibernation state refers to a state where the state of a computer immediately before power-off is stored in a nonvolatile memory so that the computer, when powered on next time, can resume operations from the state immediately before the power-off. In the hibernation state, the switches <NUM> to <NUM> are in the OFF state as with the case of the power off state. In the hibernation state, the state of the image forming apparatus <NUM> immediately before shifting to the hibernation state is stored in the HDD <NUM>. When returning from the hibernation state, the image forming apparatus <NUM> can return quickly by using the information stored in the HDD <NUM>. While the power off state has been described to be a state where the power supply to the components of the image forming apparatus <NUM> is stopped, the power off state is not limited to such a state that the power supply to all the portions of the image forming apparatus <NUM> is stopped. For example, the power off state may include a suspend state where the power supply to the RAM <NUM> is maintained. A suspend state refers to a state where the state of a computer immediately before power-off is stored in a volatile memory (e.g., the RAM <NUM>) so that the computer, when powered on next time, can resume operations from the state immediately before the power-off. The timer <NUM> is configured to be driven by a battery. The timer <NUM> is driven even in the power off state.

In the second sleep state, as illustrated in <FIG> and <FIG>, power is supplied to the power supply control unit <NUM>, the RAM <NUM>, the LAN controller <NUM>, the human body detection sensor <NUM>, the sheet detection sensor <NUM>, the document detection sensor <NUM>, and the buttons <NUM> of the operation unit <NUM>. Note that the devices to which the power is supplied in the second sleep state are just an example. In the second sleep state, no power is supplied to the CPU <NUM>, the ROM <NUM>, the HDD <NUM>, the image processing unit <NUM>, the scanner unit <NUM>, and the printer unit <NUM>. In the second sleep state, the first power supply unit <NUM> supplies power to the devices of the first power supply system (the power supply control unit <NUM>, the RAM <NUM>, the LAN controller <NUM>, the human body detection sensor <NUM>, the sheet detection sensor <NUM>, the document detection sensor <NUM>, and the buttons <NUM>). In the second sleep state, as illustrated in <FIG>, the switches <NUM> and <NUM> are in the ON state. The other switches <NUM> to <NUM> are in the OFF state. In the second sleep state, the user's operation on the buttons <NUM> of the operation unit <NUM> can be accepted. In the second sleep state, the LAN controller <NUM> can receive a packet transmitted from the external apparatus <NUM>. In the second sleep state, the human body detection sensor <NUM> can detect the approach of a person to the image forming apparatus <NUM>. In the second sleep state, the sheet detection sensor <NUM> can detect that a sheet is set on the manual feed tray <NUM>. In the second sleep state, the document detection sensor <NUM> can detect that a document is set on the tray <NUM>.

The first sleep state is a state for responding to an inquiry from the network <NUM> without activating the entire controller <NUM>. In the first sleep state, the first power supply unit <NUM> supplies power to at least the CPU <NUM> and the HDD <NUM>. As a result, the CPU <NUM> can return a response to a packet to which no proxy response can be made, received by the LAN controller <NUM>, by using information stored in the HDD <NUM>. In the first sleep state, as illustrated in <FIG> and <FIG>, power is supplied to the power supply control unit <NUM>, the RAM <NUM>, the LAN controller <NUM>, the buttons <NUM>, the CPU <NUM>, and the ROM <NUM>. In the first sleep state, power is also supplied to the human body detection sensor <NUM>, the sheet detection sensor <NUM>, the document detection sensor <NUM>, and the HDD <NUM>. In the first sleep state, no power is supplied to the devices of the second and third power supply systems. In the first sleep state, as illustrated in <FIG>, the switches <NUM>, <NUM>, and <NUM> are in the ON state. The switches <NUM>, <NUM>, 421a, 421b, 422a and 422b are in the OFF state. Note that the devices to which the power is supplied in the first sleep state are just an example.

The adjustment state is a state to which the image forming apparatus <NUM> shifts to prevent the photosensitive drum <NUM> and a blade for scraping toner off the photosensitive drum <NUM> from contacting with each other at the same position for a long time. If the image forming apparatus <NUM> shifts to the adjustment state, the photosensitive drum <NUM> rotates to change the relative position between the photosensitive drum <NUM> and the blade. In the adjustment state, as illustrated in <FIG> and <FIG>, power is supplied to the printer control unit <NUM> and the printer drive unit <NUM>, and not to the CPU <NUM> or the HDD <NUM>. In the adjustment state, as illustrated in <FIG>, the switches <NUM>, <NUM>, <NUM>, <NUM>, 421a and 421b are in the ON state. The switches <NUM>422a and 422b are in the OFF state.

In the standby state, as illustrated in <FIG> and <FIG>, power is supplied to the components of the controller <NUM>, the operation unit <NUM>, the printer unit <NUM>, and the scanner unit <NUM>. More specifically, in the standby state, the switches <NUM> to <NUM> of <FIG> are in the ON state.

Now, the power supply control unit <NUM> will be described in detail.

The power supply control unit <NUM> is a complex programmable logic device (CPLD). The power supply control unit <NUM> controls the shift of the image forming apparatus <NUM> to each of the above-described power states. The power supply control unit <NUM> is supplied with power in the second sleep state, and detects a plurality of types of return factors from the second sleep state. As illustrated in <FIG>, the power supply control unit <NUM> receives signals NW-<NUM> and NW-<NUM> as return factors from the LAN controller <NUM>. The signal NW-<NUM> is output to the power supply control unit <NUM> when the LAN controller <NUM> receives a PDL job. The signal NW-<NUM> is output to the power supply control unit <NUM> when the LAN controller <NUM> receives a packet to which no proxy response can be made. The power supply control unit <NUM> further receives a signal P as a return factor from the buttons <NUM> of the operation unit <NUM>. The signal P is output to the power supply control unit <NUM> when the buttons <NUM> are operated by the user. The power supply control unit <NUM> further receives a signal Q as a return factor from the human body detection sensor <NUM>. The signal Q is output to the power supply control unit <NUM> when the human body detection sensor <NUM> detects a person approaching the image forming apparatus <NUM>. The power supply control unit <NUM> further receives a signal R as a return factor from the timer <NUM>. The signal R is output to the power supply control unit <NUM> when the timer <NUM> has counted a set time. The time is set in the timer <NUM> by the CPU <NUM> before the image forming apparatus <NUM> shifts to the second sleep state. The power supply control unit <NUM> further receives a signal V as a return factor from the document detection sensor <NUM>. The signal V is output to the power supply control unit <NUM> when the document detection sensor <NUM> detects a document. The power supply control unit <NUM> further receives a signal W as a return factor from the sheet detection sensor <NUM> which is arranged on the manual feed tray <NUM>. The signal W is output to the power supply control unit <NUM> when a sheet is set on the manual feed tray <NUM>.

The power supply control unit <NUM> changes the states of the switches <NUM> to <NUM> to the ON state or the OFF state based on the logic of the above-described return factors (signals NW-<NUM>, NW-<NUM>, P, Q, R, V, and W).

If the signal NW-<NUM> is input to the power supply control unit <NUM>, the power supply control unit <NUM> serving as a signal output unit outputs the control signals E, F, K, J, and H (changes the signal levels to "high"). As a result, the image forming apparatus <NUM> shifts to the standby state. If the signal NW-<NUM> is input to the power supply control unit <NUM>, the power supply control unit <NUM> does not output a control signal S1 or T (changes the signal levels to "low").

If the signal P, Q, V, or W is input to the power supply control unit <NUM>, the power supply control unit <NUM> similarly outputs the control signals E, F, K, J, and H (changes the signal levels to "high"), and the image forming apparatus <NUM> shifts to the standby state. If the signal P or Q is input to the power supply control unit <NUM>, the power supply control unit <NUM> further outputs the control signals S1 and T (changes the signal levels to "high"). If the signal V is input to the power supply control unit <NUM>, the power supply control unit <NUM> further outputs the control signal S1 (changes the signal level to "high") and does not output the control signal T (changes the signal level to "low"). If the signal W is input to the power supply control unit <NUM>, the power supply control unit <NUM> further outputs the control signal T (changes the signal level to "high") and does not output the control signal S1 (changes the signal level to "low").

If the signal NW-<NUM> is input to the power supply control unit <NUM>, the power supply control unit <NUM> outputs the control signals E and H (changes the signal levels to "high"). As a result, the image forming apparatus <NUM> shifts to the first sleep state.

If the signal R is input to the power supply control unit <NUM>, the power supply control unit <NUM> outputs the control signals F and J (changes the signal levels to "high"). As a result, the image forming apparatus <NUM> shifts to the adjustment state. If the signal R is input to the power supply control unit <NUM>, the power supply control unit <NUM> outputs a control signal S2 (changes the signal level to "high").

The signal D indicating the state of the power switch <NUM> is also input to the power supply control unit <NUM>. The signal D is input to the power supply control unit <NUM> if the power switch <NUM> is changed to the OFF state by the user's operation. If the signal D is input to the power supply control unit <NUM>, the power supply control unit <NUM> outputs the control signals E, F, H, J, K and G (changes the signal levels to "Low"). As a result, the image forming apparatus <NUM> shifts to the power off state.

<FIG> is a flowchart illustrating processing by which the image forming apparatus <NUM> returns from the second sleep state. <FIG> are sequence diagrams of the signals input to the power supply control unit <NUM> and the signals output from the power supply control unit <NUM>. Signal processing performed by the power supply control unit <NUM> when the image forming apparatus <NUM> returns from the second sleep state will be described with reference to <FIG>.

In step S100, the power supply control unit <NUM> detects any one of the signals NW-<NUM>, NW-<NUM>, P, Q, R, V, and W as a return factor.

As illustrated in <FIG> and <FIG>, if the LAN controller <NUM> receives a packet to which no proxy response can be made, the LAN controller <NUM> inputs the signal NW-<NUM> to the power supply control unit <NUM> (the signal NW-<NUM> becomes a "high" level). If the signal NW-<NUM> becomes the "high" level, then in step S111, the power supply control unit <NUM> changes the signal level of the control signal H to "high". This changes the switch <NUM> to the ON state, and the first power supply unit <NUM> supplies power to the CPU <NUM>, the ROM <NUM>, and the HDD <NUM>. As a result, the image forming apparatus <NUM> shifts from the second sleep state to the first sleep state.

As illustrated in <FIG> and <FIG>, if the LAN controller <NUM> receives a PDL job, the LAN controller <NUM> inputs the signal NW-<NUM> to the power supply control unit <NUM> (the signal level of the signal NW-<NUM> becomes "high"). If the signal NW-<NUM> becomes the "high" level, then in step S121, the power supply control unit <NUM> changes the signal level of the control signal H to "high". As a result, the switch <NUM> is changed to the ON state, and the first power supply unit <NUM> supplies power to the CPU <NUM>, the ROM <NUM>, and the HDD <NUM>.

In step S122, the power supply control unit <NUM> changes the signal level of the control signal F to "high". As a result, the second power supply unit <NUM> and the third power supply unit <NUM> are powered on. In step S123, when the voltage levels of the second power supply unit <NUM> and the third power supply unit <NUM> stabilize, the power supply control unit <NUM> changes the signal levels of the control signals J and K to "high". As a result, power is supplied to the printer unit <NUM> and the scanner unit <NUM>. As a result, the image forming apparatus <NUM> shifts from the second sleep state to the standby state. In this example, the power has been described to be supplied to both the printer unit <NUM> and the scanner unit <NUM> if a PDL job is received. However, the present exemplary embodiment is not limited thereto. For example, if a PDL job is received, the power may be supplied to the printer unit <NUM> and not to the scanner unit <NUM>.

As illustrated in <FIG> and <FIG>, if the user presses a button <NUM>, the signal P is input from the button <NUM> to the power supply control unit <NUM> (the signal level of the signal P becomes "high"). If the human body detection sensor <NUM> detects a person, the signal Q is input from the human body detection sensor <NUM> to the power supply control unit <NUM> (the signal level of the signal Q becomes "high"). If the signal P or Q becomes the "high" level, then in step S130, the power supply control unit <NUM> changes the signal levels of the control signals S1 and T to "high". In step S131, the power supply control unit <NUM> changes the signal level of the control signal H to "high". As a result, the switch <NUM> is changed to the ON state, and the first power supply unit <NUM> supplies power to the CPU <NUM>, the ROM <NUM>, and the HDD <NUM>.

In step S132, the power supply control unit <NUM> changes the signal level of the control signal F to "high". As a result, the second power supply unit <NUM> and the third power supply unit <NUM> are powered on. In step S133, when the voltage levels of the second power supply unit <NUM> and the third power supply unit <NUM> stabilize, the power supply control unit <NUM> changes the signal levels of the control signals J and K to "high". As a result, power is supplied to the printer unit <NUM> and the scanner unit <NUM>. Thus, the image forming apparatus <NUM> shifts from the second sleep state to the standby state.

As illustrated in <FIG> and <FIG>, if the timer <NUM> has counted a predetermined time, the timer <NUM> inputs the signal R to the power supply control unit <NUM> (the signal level of the signal R becomes "high"). If the signal R becomes the "high level", then in step S140, the power supply control unit <NUM> changes the signal level of the control signal S2 to "high".

In step S142, the power supply control unit <NUM> changes the signal level of the control signal F to "high". As a result, the second power supply unit <NUM> and the third power supply unit <NUM> are powered on. In step S143, when the voltage levels of the second power supply unit <NUM> and the third power supply unit <NUM> stabilize, the power supply control unit <NUM> changes the signal level of the control signal J to "high". As a result, power is supplied to the printer unit <NUM>. Thus, the image forming apparatus <NUM> shifts from the second sleep state to the adjustment state.

As illustrated in <FIG> and <FIG>, if the document detection sensor <NUM> detects a document, the document detection sensor <NUM> inputs the signal V to the power supply control unit <NUM> (the signal level of the signal V becomes "high"). If the signal V becomes the "high" level, then in step S150, the power supply control unit <NUM> changes the signal level of the control signal S1 to "high". In step S151, the power supply control unit <NUM> changes the signal level of the control signal H to "high". As a result, the switch <NUM> is changed to the ON state, and the first power supply unit <NUM> supplies power to the CPU <NUM>, the ROM <NUM>, and the HDD <NUM>.

In step S152, the power supply control unit <NUM> changes the signal level of the control signal F to "high". As a result, the second power supply unit <NUM> and the third power supply unit <NUM> are powered on. In step S153, when the voltage levels of the second power supply unit <NUM> and the third power supply unit <NUM> stabilize, the power supply control unit <NUM> changes the signal levels of the control signals J and K to "high". As a result, power is supplied to the printer unit <NUM> and the scanner unit <NUM>. As a result, the image forming apparatus <NUM> shifts from the second sleep state to the standby state.

As illustrated in <FIG> and <FIG>, if the sheet detection sensor <NUM> detects a sheet, the sheet detection sensor <NUM> inputs the signal W to the power supply control unit <NUM> (the signal level of the signal W becomes "high"). If the signal W becomes the "high" level, then in step S160, the power supply control unit <NUM> changes the signal level of the control signal T to "high". In step S161, the power supply control unit <NUM> changes the signal level of the control signal H to "high". As a result, the switch <NUM> is changed to the ON state, and the first power supply unit <NUM> supplies power to the CPU <NUM>, the ROM <NUM>, and the HDD <NUM>.

In step S162, the power supply control unit <NUM> changes the signal level of the control signal F to "high". As a result, the second power supply unit <NUM> and the third power supply unit <NUM> are powered on. In step S163, when the voltage levels of the second power supply unit <NUM> and the third power supply unit <NUM> stabilize, the power supply control unit <NUM> changes the signal levels of the control signals J and K to "high". As a result, power is supplied to the printer unit <NUM> and the scan unit <NUM>. Thus, the image forming apparatus <NUM> shifts from the second sleep state to the standby state.

<FIG> is a flowchart illustrating return processing of the printer unit <NUM>.

The return processing of the printer unit <NUM> will be described with reference to <FIG>.

In step S191, the voltage supplied from the second power supply unit <NUM> to the printer control unit <NUM> of the printer unit <NUM> stabilizes. In step S192, the printer control unit <NUM> performs reset cancellation. In step S193, the reset-canceled printer control unit <NUM> checks the logic of the signals input to the printer control unit <NUM>.

If neither of the control signals S1 and S2 is input to the printer control unit <NUM> (the signal levels of the control signals S1 and S2 are both "low" levels; SIGNAL S1 = LOW, SIGNAL S2 = LOW in step S193), then in step S194, the printer control unit <NUM> performs a preparation operation of the printer control unit <NUM>. The preparation operation refers to an operation to be performed before the printer unit <NUM> becomes ready for printing. The preparation operation includes a rotating operation of the photosensitive drum <NUM> and a rotating operation of the fixing device <NUM>. When the preparation operation is completed, the printer unit <NUM> becomes ready for printing.

If the control signal S2 is input to the printer control unit <NUM> (the signal level of the control signal S2 is a "high" level; SIGNAL S1 = LOW, SIGNAL S2 = HIGH in step S193), then in step S195, the printer control unit <NUM> performs an adjustment operation of the printer drive unit <NUM>. The blade for scraping toner off the surface of the photosensitive drum <NUM> may leave a mark on the surface of the photosensitive drum <NUM> if the photosensitive drum <NUM> and the blade make contact with each other for a long time. The adjustment operation refers to an operation of changing the relative position between the photosensitive drum <NUM> and the blade so that the blade leaves no mark. More specifically, the printer control unit <NUM> intermittently rotates the photosensitive drum <NUM>.

If the control signal S1 is input to the printer control unit <NUM> (the signal level of the control signal S1 is a "high" level; SIGNAL S1 = HIGH, SIGNAL S2 = LOW in step S193), the printer control unit <NUM> does not drive the printer drive unit <NUM>.

<FIG> is a flowchart illustrating return processing of the scanner unit <NUM>.

The return processing of the scanner unit <NUM> will be described with reference to <FIG>.

In step S196, the voltage supplied from the second power supply unit <NUM> to the scanner control unit <NUM> of the scanner unit <NUM> stabilizes. In step S197, the scanner control unit <NUM> performs reset cancellation. In step S198, the reset-canceled scanner control unit <NUM> checks the logic of the signal input to the scanner control unit <NUM>.

If the control signal T is not input to the scanner control unit <NUM> (the signal level of the control signal T is a "low" level; SIGNAL T = LOW in step S198), then in step S199, the scanner control unit <NUM> performs a preparation operation of the scanner drive unit <NUM>. The preparation operation refers to a preparation operation to be performed before the scanner unit <NUM> becomes ready for scanning. The preparation operation includes a homing operation of the optical unit <NUM> and a lighting operation of the lamp <NUM>. When the preparation operation is completed, the scanner unit <NUM> becomes ready to read a document.

If the control signal T is input to the scanner control unit <NUM> (the signal level of the control signal T is a "high" level; SIGNAL T = HIGH in step S198), the scanner control unit <NUM> does not drive the scanner drive unit <NUM>.

<FIG> is a flowchart illustrating an operation of the power supply control unit <NUM> when the user selects a function button on the selection screen displayed on the display unit <NUM>. When the image forming apparatus <NUM> enters the standby state, the selection screen (see <FIG>) is displayed on the display unit <NUM> of the operation unit <NUM>. Here, an operation of the image forming apparatus <NUM> having entered the standby state with the signal levels of the control signals S1 and T "high" will be described.

In step S210, if the user presses the copy button 122a of the display unit <NUM> (YES in step S210), then in step S211, the power supply control unit <NUM> changes the signal levels of the control signals S1 and T to "low". The printer control unit <NUM> then performs the preparation operation of the printer drive unit <NUM>. As a result, the printer unit <NUM> becomes ready for printing. The scanner control unit <NUM> performs the preparation processing of the scanner drive unit <NUM>. As a result, the scanner unit <NUM> becomes ready to read a document. Consequently, the user can copy a document by using both the scan function and the print function.

In step S220, if the user presses the scan button 122b of the display unit <NUM> (YES in step S220), then in step S221, the power supply control unit <NUM> changes the signal level of the control signal T to "low". The signal level of the control signal S1 is maintained at "high". The scanner control unit <NUM> then performs the preparation operation of the scanner drive unit <NUM>. As a result, the scanner unit <NUM> becomes ready to read a document. Here, the preparation operation of the printer drive unit <NUM> is restricted. Consequently, the user can store an image read by using the scan function into the HDD <NUM>.

In step S230, if the user presses the FAX button 122c of the display unit <NUM> (YES in step S230), then in step S231, the power supply control unit <NUM> changes the signal level of the control signal T to "low". The signal level of the control signal S1 is maintained at "high". The scanner control unit <NUM> then performs the preparation operation of the scanner drive unit <NUM>. As a result, the scanner unit <NUM> becomes ready to read a document. Here, the preparation operation of the printer drive unit <NUM> is restricted. Consequently, the user can facsimile image data on a document read by using the scan function.

In step S240, if the user presses the print button 122d of the display unit <NUM> (YES in step S240), then in step S241, the power supply control unit <NUM> changes the signal level of the control signal S1 to "low". The signal level of the control signal T is maintained at "high". The printer control unit <NUM> then performs the preparation processing of the printer drive unit <NUM>. As a result, the printer unit <NUM> becomes ready for printing. Here, the preparation operation of the scanner drive unit <NUM> is restricted. Consequently, the user can perform printing based on a print job(s) stored in the HDD <NUM> and/or a print job(s) stored in a server by using the print function.

According to the above-described configuration, if the image forming apparatus <NUM> receives a PDL job in the second sleep state, the image forming apparatus <NUM> can perform the preparation operation of the printer drive unit <NUM> without waiting for the user's operation on the selection screen. In other words, if the image forming apparatus <NUM> receives a PDL job, the printer unit <NUM> immediately becomes ready for printing.

If the human body detection sensor <NUM> detects a person or the buttons <NUM> are pressed in the second sleep state, the preparation operations of the printer unit <NUM> and the scanner unit <NUM> are restricted. In such a case, the driving systems of the printer unit <NUM> and the scanner unit <NUM> are not operated (the motors of the photosensitive drum <NUM> and the fixing device <NUM> are not driven). The image forming apparatus <NUM> therefore shifts quietly to the standby state without producing noise related to the operation of the driving systems.

After the shift to the standby state where the driving systems are not operated, the user may press one of the function buttons 122a to 122d to determine the function to use. In such a case, the driving system(s) of the printer unit <NUM> and/or the scanner unit <NUM> is/are operated. In the standby state where the driving systems are not operated, stable power has already been supplied to the printer unit <NUM> and the scanner unit <NUM>, and the printer unit <NUM> and the scanner unit <NUM> have already been reset-cancelled as well. Consequently, the printer unit <NUM> becomes ready for printing and/or the scanner unit <NUM> becomes ready for reading immediately after the user presses one of the function buttons 122a to 122d.

If the document detection sensor <NUM> detects a document, the driving system of the scanner unit <NUM> performs the preparation operation and the driving system of the printer unit <NUM> does not perform the preparation operation. If the document detection sensor <NUM> detects a document, the scanner unit <NUM> is likely to be used. To make the function of the scanner unit <NUM> usable, the scanner drive unit <NUM> of the scanner unit <NUM> therefore performs the preparation operation. However, even though the document detection sensor <NUM> detects a document, whether to use the printer unit <NUM> is not determined. For example, the copy function may be performed. An image of the scanned document may be stored in the HDD <NUM>, or may be facsimiled. The printer drive unit <NUM> of the printer unit <NUM> therefore does not perform the preparation operation. The printer drive unit <NUM> performs the preparation operation when the function of the printer unit <NUM> is determined to be used.

If the sheet detection sensor <NUM> detects a sheet, the driving system of the printer unit <NUM> performs the preparation operation, and the driving system of the scanner unit <NUM> does not perform the preparation operation. If the sheet detection sensor <NUM> detects a sheet, the printer unit <NUM> is likely to be used. To make the function of the printer unit <NUM> usable, the printer drive unit <NUM> of the printer unit <NUM> therefore performs the preparation operation. However, even though the sheet detection sensor <NUM> detects a sheet, whether to use the scanner function is not determined. The scanner drive unit <NUM> of the scanner unit <NUM> therefore does not perform the preparation operation. The scanner drive unit <NUM> performs the preparation operation when the function of the scanner unit <NUM> is determined to be used.

The above-described exemplary embodiment has dealt with the case where the power supply control unit <NUM>, a hardware logic circuit, performs the steps illustrated in <FIG> and <FIG>. However, the present exemplary embodiment is not limited thereto. The power supply control unit <NUM> may be a processor, and the processor may execute a program to perform the steps illustrated in <FIG> and <FIG>.

The functions illustrated in the flowcharts of the present exemplary embodiment may be implemented by a processing apparatus (CPU or processor), such as a personal computer, executing software (program) obtained via a network or various storage media.

The image forming apparatus according to the present exemplary embodiment can prevent the useless consumption of power and the production of noise by the preparation operation of the printer unit and the like when the image forming apparatus returns from the power saving state.

The image forming apparatus according to the present exemplary embodiment supplies power to the printer unit and the like before the printer unit and the like are determined to be used. The image forming apparatus can thus reduce time for the functions of the printer unit and the like to become usable when the printer unit and the like are determined to be used.

Embodiments of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions recorded on a storage medium (e.g., non-transitory computer-readable storage medium) to perform the functions of one or more of the above-described embodiment(s) of the present invention, and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment (s). The computer may comprise one or more of a central processing unit (CPU), micro processing unit (MPU), or other circuitry, and may include a network of separate computers or separate computer processors.

Claim 1:
An image forming apparatus (<NUM>) comprising:
a motor configured to rotate a photosensitive drum (<NUM>) of the image forming apparatus (<NUM>);
a human sensor (<NUM>) capable of sensing a human without contacting the human;
a display control means (<NUM>) for displaying a screen including at least an instruction portion for selecting a copy function (122a) and an instruction portion for selecting a facsimile function (122c) on a display (<NUM>) on a basis of a sensing result of the human sensor, without driving the motor on the basis of the sensing result of the human sensor (<NUM>); and
a control means (<NUM>) for driving the motor on a basis of an operation on the instruction portion for selecting the copy function (122a) displayed on the screen (<NUM>), and after the operation on the instruction portion for selecting the copy function (122a), executing copying on a basis of an operation on a copy execution instruction portion for executing the copy function.