Electronic device

Abstract

To provide an apparatus that can reliably switch a power state with a simple and inexpensive configuration.SOLUTION: In an image forming apparatus 100, an operation unit 305 and a CPU 301 are connected to each other by a serial communication line 309 and a power instruction signal line 310 being a single signal line. The operation unit 305 notifies power instructions to the CPU 301 through serial communication through the serial communication line 309 and a signal pattern of a power instruction signal 310s output to the power instruction signal line 310. The CPU 301 receives the power instructions from the operation unit 305 through the serial communication and the signal pattern of the power instruction signal 310s, and switches the power state of the image forming apparatus 100 according to the power instructions.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to electronic devices such as image forming apparatuses. [Background technology]

[0002] Electronic devices such as image forming devices typically have multiple power states, such as power OFF and power ON, as well as a sleep state (power saving state) for reducing power consumption during standby and a restart state for example when updating the system.

[0003] In addition, a common configuration is that the master side, which manages the system status, instructs the slave side, which manages devices such as power supplies and actuators, on the next power status via serial communication. Similarly, it is common to use hardware signals as timing signals in addition to serial communication.

[0004] When instructing the power state from the master side to the slave side via serial communication, it is possible to easily increase the options for the instruction content by defining multiple power state instructions as parameters to be included in the packet. Note that with serial communication, it is possible that the state instruction cannot be properly given when a communication error occurs due to the effects of noise, etc. For example, even if a restart should be instructed, there may be cases where the power is turned off as an abnormality handling process because the instruction cannot be given via serial communication.

[0005] Patent Document 1 proposes a method of using a combination of multiple hard signals as a means for switching between multiple power states even when an abnormality occurs. Patent Document 1 provides a reset signal for resetting a drive circuit unit, and a different control signal for switching the state even when the reset signal is supplied, so that the power state can be reliably switched even when an abnormality occurs in the drive circuit unit of the hard signal. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2013-172509 A Summary of the Invention [Problem to be solved by the invention]

[0007] In the case of a configuration in which the power state is notified by serial communication or the like as described above, it is desirable to be able to appropriately switch the power state of the device even when a communication abnormality or the like occurs. For example, even when a communication abnormality or the like occurs, it is desirable to switch the power state after completion of preparation processing or the like according to the power state to be transitioned to. To achieve this, a configuration using control signals via multiple signal lines as in Patent Document 1 is conceivable.

[0008] However, when using a configuration that uses control signals via multiple signal lines as in Patent Document 1, the more states to be controlled, the more signal lines are required. Thus, the conventional technology has had problems such as an increase in the size of the control board and an increase in costs.

[0009] The present invention has been made to solve the above problems, and has an object to provide a mechanism that can reliably switch power states with a simple and inexpensive configuration. [Means for solving the problem]

[0010] The present invention relates to An electronic device capable of switching between multiple power states comprises an instruction unit capable of issuing multiple types of instructions to switch the power state of the electronic device, a control unit that switches the power state of the electronic device in accordance with the instructions from the instruction unit, a communication line that connects the instruction unit and the control unit for a specified communication, and a single signal line that connects the instruction unit and the control unit, wherein the instruction unit notifies the control unit of the instructions by each of the specified communication via the communication line and the pattern of a signal output to the signal line, and the control unit is capable of receiving the instructions from the instruction unit by each of the specified communication via the communication line and the pattern of a signal input from the signal line, the multiple types of instructions are each defined according to the elapsed time from when a signal flowing through the signal line becomes a specified logical value to when it changes to another logical value, and the signal pattern is a signal pattern corresponding to the definition. Effect of the Invention

[0011] According to the present invention, it is possible to provide a device that can reliably switch power states with a simple and inexpensive configuration. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a configuration of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a control block diagram showing an example of the configuration of the image forming apparatus according to the present embodiment. [Diagram 3] FIG. 4 is a diagram showing an example of a power state of the image forming apparatus according to the embodiment. [Figure 4] 5 is a flowchart showing an example of processing by a CPU in the image forming apparatus according to the first embodiment. [Diagram 5] 10 is a flowchart showing an example of a signal pattern determination process for a power instruction signal. [Figure 6] 6A and 6B are diagrams showing examples of definitions of signal patterns of power instruction signals; [Figure 7] 10 is a flowchart showing an example of processing by a CPU in an image forming apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [First embodiment] FIG. 1 is a cross-sectional view showing an example of the configuration of an image forming apparatus 100 which is an embodiment of an electronic device of the present invention. 2 is a control block diagram showing an example of the configuration of the image forming apparatus 100 according to an embodiment of the present invention. The basic configuration will be described below with reference to FIGS.

[0014] The control unit 300 shown in FIG.

[0015] An operation unit 305 including a touch panel as an instruction / display unit is connected to the CPU 301 via a serial communication line 309 and a power instruction signal line 310. A user can request the CPU 301 to perform a desired operation such as executing a print job or operating a power source 312 through the operation unit 305. The operation unit 305 functions as an instruction unit capable of issuing power instructions (of which there are multiple types) to the CPU 301 to switch the power state of the image forming apparatus 100. The CPU 301 operates to switch the power state of the image forming apparatus 100 according to the power instructions issued from the operation unit 305. The power instruction signal line 310 is a single signal line. The operation unit 305 outputs a power instruction signal 310s to the power instruction signal line 310. The operation unit 305 changes the logic (logical value (level)) of the power instruction signal 310s based on a pattern defined in advance for each of the multiple types of power instructions (details will be described later).

[0016] In addition, the CPU 301 can also be connected to a PC 307 via an external I / F 306 that is an interface with an external device connected to an operation unit 305 .

[0017] The CPU 301 starts operation upon receiving an instruction to start a print operation or an instruction to return from a sleep mode (power saving state) from the operation unit 305 or the PC 307. For example, when a user issues an instruction to start a print operation from the PC 307, the CPU 301 controls the driving of an image forming unit 308 and various loads 311 constituted by connected motors, heaters, etc.

[0018] As described above, the CPU 301 is capable of controlling the image forming unit 308. The image forming unit 308 is capable of controlling high voltages and driving of the cartridges 120a, 120b, 120c, and 120d including photoconductors, the intermediate transfer belt 130, the primary transfer units 123a to 123d, the secondary transfer unit 140, and the like, and of controlling the laser scanners 122a to 122d.

[0019] The ROM 303 stores image formation procedures and procedures of flowcharts used in the following description as programs. The non-volatile memory 304 can hold data even after the power supply to the CPU 301 is stopped. The non-volatile memory 304 saves data stored in the RAM 302 that continues to be used even after the power is turned off / on.

[0020] The power switch 313 is used to turn the power of the device on or off by user operation. The CPU 301 monitors the state of the power switch 313 and operates the power supply 312 according to the state of the power switch 313.

[0021] <Explanation of basic image formation operations> The basic image forming operation will be described with reference to FIGS. When a user executes a print job from PC 307 connected to external I / F 306 and a print operation start instruction is sent to CPU 301, CPU 301 starts the paper feed operation from paper feed cassettes 150a, 150b, etc. In this paper feed operation, a conveyance motor serving as a drive source for paper feed pickup rollers 151a, 151b is driven to rotate paper feed pickup rollers 151a, 151b, and paper is fed and conveyed one sheet at a time in paper feed cassettes 150a, 150b. At this time, CPU 301 monitors whether the paper feed operation has been performed normally using paper feed pickup sensors 152a, 152b.

[0022] Furthermore, CPU 301 starts the image forming operation by cartridges 120a, 120b, 120c, and 120d so as to be in time for the paper to arrive at secondary transfer unit 140. In this image forming operation, a toner image is formed on intermediate transfer belt 130 by primary transfer units 123a to 123d.

[0023] Cartridge 120a is a cartridge for forming a yellow (hereinafter sometimes referred to as "Y") image. Cartridge 120b is a cartridge for forming a magenta (hereinafter sometimes referred to as "M") image. Cartridge 120c is a cartridge for forming a cyan (hereinafter sometimes referred to as "C") image. Cartridge 120d is a cartridge for forming a black (hereinafter sometimes referred to as "K") image. Cartridges 120a, 120b, 120c, and 120d are configured to be mountable and removable by the user.

[0024] The paper fed from paper feed cassette 150a and paper feed cassette 150b by the paper feeding operation is conveyed downstream of the image forming apparatus by conveyance path rollers 153, 154, and 155. CPU 301 detects the position of the conveyed paper by monitoring the output of pre-registration conveyance sensor 160. Then, CPU 301 controls the conveyance of the paper so that the leading edge of the paper and the leading edge of the toner image on intermediate transfer belt 130 coincide with each other at secondary transfer unit 140, taking into consideration the timing when the leading edge of the paper reaches pre-registration conveyance sensor 160. In this control, for example, if CPU 301 determines that the paper has arrived earlier than the toner image, registration rollers 161 stop the paper for a predetermined time and then resume conveyance, thereby making the leading edge of the paper coincide with the leading edge of the toner image.

[0025] In the manner described above, a secondary transfer voltage is applied to the paper and toner image that have reached secondary transfer unit 140, whereby the toner image is transferred onto the paper. After the secondary transfer, the paper is transported to a fixing device 170, and when the toner image on the paper is heated and fixed to the paper by the fixing device 170, the paper is further transported to a downstream portion of the image forming apparatus.

[0026] When the leading edge of the paper after fixing reaches the paper transport sensor 171, the CPU 301 determines whether the paper should be transported to the paper transport path 230 or the paper transport path 231, according to an instruction previously specified from the operation unit 305 or the PC 307 connected via the external I / F 306. At this time, the CPU 301 switches the operation of the transport flapper 172 according to the determination, thereby switching the destination of the paper. Specifically, when the image forming operation corresponds to printing on the front side of a double-sided print instruction, the transport flapper 172 is switched so that the paper is transported to the paper transport path 230, whereas when the image forming operation corresponds to printing on the back side of a single-sided print or double-sided print, the transport flapper 172 is switched so that the paper is transported to the paper transport path 231.

[0027] The following describes the case where the paper is transported to the paper transport path 231. The paper conveyed to paper conveying path 231 is further conveyed by conveying rollers 232 to the downstream portion of the image forming apparatus. Here, similar to the above-mentioned switching, CPU 301 switches the operation of paper conveying flapper 190 according to an instruction specified in advance from operation unit 305 or PC 307 connected via external I / F 306. This allows the configuration to switch whether paper is conveyed to paper conveying path 180 side or paper conveying path 181 side. If the user's designated paper discharge destination is paper discharge tray 200, the paper is conveyed to paper conveying path 180 side, and if the designated paper discharge destination is paper discharge tray 196, the paper is conveyed to paper conveying path 181 side. The above-described basic image forming operation is merely an example, and the present invention is not limited to the above-described configuration.

[0028] <Power state description> Next, the power supply state of each unit according to the power state of the image forming apparatus will be described with reference to FIG. FIG. 3 is a diagram showing an example of the power state of the image forming apparatus according to the present embodiment. FIG. 3(a) shows the device in a standby state. FIG. 3(b) shows the power-off state.

[0029] The standby state (a) is a state in which power is supplied to all units including the control unit 300, the operation unit 305, and the external I / F 306. The power-off state (b) is a state in which power is supplied only to the minimum units necessary for making a startup determination, such as the CPU 301, RAM 302, ROM 303, and non-volatile memory 304. In the power-off state (b), power is not supplied to the image forming unit 308, various loads 311, operation unit 305, and external I / F 306.

[0030] For example, when the operation unit 305 instructs to turn off the power while the device is in standby, or when it is detected that the power SW 313 has been turned off by a user operation, the state of the device transitions from the standby state (a) to the power off state (b). Note that when it is detected in the power off state (b) that the power SW 313 has been turned on by a user operation, the state of the device transitions from the power off state (b) to the standby state (a).

[0031] Furthermore, if the operation unit 305 issues an instruction to restart (reboot) the device while it is in standby, the device state transitions from the standby state (a) to the power-off state (b) and then returns to the standby state (a) again.

[0032] The power supply state of the unit in the above power state is an example, and the present invention is not limited to the above configuration. For example, a plurality of power saving states may be provided between the standby state (a) and the power OFF state (b). In this embodiment, a first power saving state that consumes less power than the standby state (a) and consumes more power than the power OFF state (b), and a second power saving state that consumes less power than the first power saving state and consumes more power than the power OFF state (b) are provided. For example, the first power saving state corresponds to a power state in which the backlight of the display of the operation unit 305 is turned off from the standby state (a). The second power saving state corresponds to a power state in which the operating clock of the CPU 301 is further reduced from the first power saving state.

[0033] <Explanation of the overall picture of control> Fig. 4 is a flowchart showing an example of processing performed by the CPU 301 in the image forming apparatus according to the first embodiment. The processing steps shown in Fig. 4 and the flowchart in Fig. 5, which will be described later, are stored in the ROM 303 as a program, and are implemented by the CPU 301 reading and executing it.

[0034] When the CPU 301 is energized and starts processing, it monitors whether the power switch 313 is ON and continues monitoring until the power switch 313 is ON (S401). If the CPU 301 confirms that the power switch 313 is ON (Yes in S401), it first performs operation unit 305 startup processing to start energizing the operation unit 305 (S402).

[0035] When the startup process of the operation unit 305 is completed, the logic (logical value (level)) of the power instruction signal 310s input from the operation unit 305 to the CPU 301 via the power instruction signal line 310 switches to "High". Therefore, the CPU 301 monitors the logic of the power instruction signal 310s until the logic of the power instruction signal 310s switches to "High" (S403). When the CPU 301 determines that the logic of the power instruction signal 310s is "High" (Yes in S403), it proceeds to S404.

[0036] In S404, the CPU 301 executes a power startup process which is a process for supplying power to all modules to which power can be supplied, and transitions the state of the device to the standby state shown in FIG.

[0037] After that, the CPU 301 monitors whether or not there is a print request from the operation unit 305 (S405). If there is a print request from the operation unit 305 (Yes in S405), the CPU 301 advances the process to S406. In S406, the CPU 301 executes image formation processing, and advances the process to S407. On the other hand, if it is determined that there is no print request (No in S405), the CPU 301 advances the process to S407.

[0038] In S407, the CPU 301 checks whether the power switch 313 is OFF. If the power switch 313 is OFF (Yes in S407), the CPU 301 advances the process to S411. The process after S411 will be described later.

[0039] On the other hand, if it is determined that the power switch 313 is not OFF (No in S407), the CPU 301 advances the process to S408. In S408, the CPU 301 checks whether serial communication (hereinafter simply referred to as "serial communication") is possible via the serial communication line 309. The method of checking in S408 is not limited to the above, and may include, for example, transmitting and receiving a specified number of packets to check that no errors have occurred, or checking that serial communication has been performed within a specified period of time without any errors. Next, the CPU 301 checks the result of the serial communication check in S408 above, and determines whether serial communication is possible (S409).

[0040] First, the operation when it is determined in S409 above that serial communication is possible will be described. If serial communication is possible (Yes in S409), the CPU 301 advances the process to S410. In S410, the CPU 301 checks whether or not a power state switching command has been issued via serial communication. If the CPU 301 determines that a power state switching command has not been issued (No in S410), the CPU 301 returns to S405 and continues the process.

[0041] On the other hand, if reception of an instruction to switch the power state is confirmed in S410 (Yes in S410), the CPU 301 advances the process to S411.

[0042] In S411, the CPU 301 performs preparation processing according to the power state instructed by the serial notification. The preparation processing in S411 refers to, for example, processing for stopping various loads 311 such as actuators, processing for saving data to the non-volatile memory 304, processing for disconnecting serial communication, and processing for saving data inside the operation unit 305 (not shown). When the operation unit 305 completes preparation for power-off, the operation unit 305 switches the logic of the power instruction signal 310s to "Low." Therefore, in S412, the CPU 301 monitors the power instruction signal 310s and waits for the logic of the power instruction signal 310s to switch to "Low" (S412).

[0043] If the CPU 301 confirms that the logic of the power instruction signal 310s is "Low" (Yes in S412), the process proceeds to S416.

[0044] In S416, the CPU 301 executes a power-off process, which is a process for stopping the power supply to the target module according to the power state instructed by the serial communication. If the instruction in the serial communication is a power-off instruction, the power-off process in S416 transitions the state of the device to the power-off state shown in FIG. 3B. If the instruction in the serial communication is a power-saving instruction, the power-off process in S416 transitions the state of the device to a power-saving state (not shown). For example, the state transitions to a first power-saving state in which the backlight of the display of the operation unit 305 is turned off, or a second power-saving state in which the operating clock of the CPU 301 is further reduced from the first power-saving state, thereby reducing the power consumption of the device (not shown).

[0045] On the other hand, in the above S409, if the CPU 301 determines that serial communication is not possible (No in S409), the process proceeds to S413. In S413, the CPU 301 checks whether a "Low" edge of the logic of the power instruction signal 310s has been detected in order to determine whether a power state is instructed by the power instruction signal 310s. If a "Low" edge of the logic of the power instruction signal 310s has not been detected (No in S413), the CPU 301 returns to the process of S405 and continues the process.

[0046] On the other hand, if a logic "Low" edge of the power instruction signal 310s is detected (Yes in S413), the CPU 301 advances the process to S414. In S414, the CPU 301 performs a signal pattern determination process based on the detection time of the “Low” state of the power instruction signal, and proceeds to S415. The signal pattern determination process will be described later with reference to FIG.

[0047] In S415, the CPU 301 checks whether the signal pattern determination result in the above S414 indicates a forced power OFF. If it is determined that the instruction is an instruction other than a forced power OFF (first power saving state, reboot, or power OFF) (No in S415), the process proceeds to S411.

[0048] On the other hand, if the signal pattern determination result in S414 above is forced power OFF (Yes in S415), the CPU 301 advances the process to S416 and executes power OFF processing.

[0049] After executing the power-off process in S416, the CPU 301 first checks whether the instruction from the operation unit 305 was an instruction to save power (S417). If the instruction is an instruction to save power (Yes in S417), the CPU 301 returns the process to S403 and waits for the operation unit 305 to set the logic of the power instruction signal to "High." On the other hand, if the instruction from the operation unit 305 is not an instruction for power saving (No in S417), the CPU 301 advances the process to S418.

[0050] In S418, the CPU 301 checks whether the instruction from the operation unit 305 was an instruction to reboot (restart) or not. If the instruction is an instruction to reboot (Yes in S418), the CPU 301 returns the process to S402 and starts restarting the power supply. On the other hand, if the instruction is not an instruction to reboot (No in S418), the CPU 301 returns the process to S401 and waits for the power switch 313 to be turned ON as a start-up instruction by the next user operation. The above is a description of the overall picture of control in this embodiment.

[0051] <Signal pattern determination process (S414)> Fig. 5 is a flowchart showing an example of a signal pattern determination process for the power instruction signal 310s. Note that this flowchart shows the internal process of the process shown in S414 in Fig. 4. Furthermore, here, a process for determining a signal pattern based on the detection time of the "Low" state of the power instruction signal 310s is shown as an example, but is not limited to this. Also, the definition of the signal pattern of the power instruction signal 310s will be described later with reference to Fig. 6.

[0052] When the CPU 301 starts the process, the current time T Low is saved (S501). Furthermore, the CPU 301 checks whether the logic of the power instruction signal 310s has detected a "High" state, which indicates the end of the signal pattern determination (S502).

[0053] First, a case where the logic of the power instruction signal is in the "Low" state in S502 will be described. Here, the logic of the power instruction signal 310s being in the "Low" state means that the "Low" state is continuing in order to form a signal pattern (the "High" state has not yet been detected). When the logic of the power instruction signal 310s is in the “Low” state (No in S502), the CPU 301 now is obtained (S503).

[0054] Next, the CPU 301 Low From T now Time elapsed until (T now -T Low ) is the threshold T shutdown The CPU 301 determines whether the elapsed time has reached T shutdown If it is equal to or less than this (No in S504), the process returns to S502 and continues.

[0055] On the other hand, the CPU 301 detects that the elapsed time is T shutdown If it is determined that the number of times has exceeded the limit, the process proceeds to S505. In S505, the CPU 301 determines that the signal pattern determination result of the power instruction signal is a "forced power OFF" instruction, and ends the signal pattern determination process.

[0056] Here, a case where the logic of the power instruction signal is in the "High" state in the above S502 will be described. Here, the logic of the power instruction signal 310s being in the "High" state means that the signal pattern has been determined. If the logic of the power instruction signal 310s is in the "High" state (Yes in S502), the CPU 301 advances the process to S506. In S506, the CPU 301 detects the power instruction signal 310s at a time T High Save. Furthermore, the CPU 301 High and T Low Difference from (T Low -T High ) stands for T elps is calculated according to the following formula (1) (S507).

number

[0057] Next, the CPU 301 calculates T elps is the time when the "first power saving" instruction is determined. slp_min From Tslp_max Between (T slp_min <T elps ≦T slp_max ) (S508). elps T slp_min From T slp_max If it is between these (Yes in S508), the process proceeds to S513. In S513, the CPU 301 determines that the power state instruction from the operation unit 305 is a "first power saving" instruction (an instruction to switch to the first power saving state), and ends the signal pattern determination process.

[0058] On the other hand, the CPU 301 elps T slp_min From T slp_max If it is not between them (No in S508), the process proceeds to S509. In S509, the CPU 301 elps is the time when a reboot command is judged. rb_min From T rb_max Between (T rb_min <T elps ≦T rb_max At this time, the CPU 301 checks whether T elps T rb_min From T rb_max If it is between them (Yes in S509), the process proceeds to S512. In S512, the CPU 301 determines that the power state instruction from the operation unit 305 is a "reboot" instruction, and ends the signal pattern determination process.

[0059] On the other hand, the CPU 301 elps T rb_min From T rb_max If it is not between them (No in S509), the process proceeds to S510. In the S510, the CPU 301 elps is the time when the power OFF command is judged. off_min From T off_max Between (T off_min <T elps ≦T off_max ) is checked. The CPU 301 checks whether T elps Toff_min From T off_max If it is between them (Yes in S510), the process proceeds to S511. In S511, the CPU 301 determines that the power state instruction from the operation unit 305 is a "power OFF" instruction, and ends the signal pattern determination process.

[0060] On the other hand, the CPU 301 elps T off_min From T off_max If it is not between (No in S510), the process proceeds to S505. In this case, the CPU 301 determines that the power instruction is a "forced power OFF" instruction for protection processing, since the previously expected pattern was not notified, and ends the signal pattern determination process.

[0061] In this flowchart, the signal patterns to be determined are described as a "first power saving" instruction, a "power OFF" instruction, a "reboot" instruction, and a "forced power OFF" instruction, but the patterns to be determined are not limited to these. For example, the determination patterns may include a "second power saving" instruction (an instruction to switch to a second power saving state) in this embodiment.

[0062] In addition, in the present embodiment, the signal pattern is defined by the time that the power instruction signal 310s is at the "Low" logic, but this is not limiting. For example, the power instruction may be determined based on the number of times the power instruction signal toggles (the number of times the power instruction signal switches between Low and High). The above is an explanation of the signal pattern determination process.

[0063] <Signal pattern definition example> FIG. 6 is a diagram showing an example of a definition of a signal pattern of the power instruction signal 310s in this embodiment. As shown in Figure 6, the time required to determine the signal pattern T elps is the timing when the logic of the power instruction signal 310s changes to “Low”. Low The timing when the logic of the power instruction signal 310s changes to “High” is T HighIt is expressed as the elapsed time until In this example, four signal patterns are defined: "first power saving state," "reboot (restart)," "power off," and "forced power off."

[0064] In this example, first, the T elps 500 ms, and T slp_min The equivalent value is 450ms, T slp_max In other words, according to this definition example, if the period during which the logic of the power instruction signal 310s is "Low" exceeds 450 ms and is equal to or shorter than 550 ms, the CPU 301 determines that the power instruction from the operation unit 305 is a "first power saving" instruction.

[0065] Next, the T to determine "reboot" elps 1000 ms, and T rb_min The equivalent value is 950ms, T rb_max In other words, according to this definition example, if the period during which the logic of the power instruction signal 310s is "Low" exceeds 950 ms and is equal to or shorter than 1050 ms, the CPU 301 determines that the power instruction from the operation unit 305 is a "reboot" instruction.

[0066] Also, the T for determining "power OFF" elps 1500 ms, and T off_min The equivalent value is 1450ms, T off_max In other words, according to this definition example, if the period during which the logic of the power instruction signal 310s is "Low" exceeds 1450 ms and is equal to or shorter than 1550 ms, the CPU 301 determines that the power instruction from the operation unit 305 is a "power OFF" instruction.

[0067] Finally, the T for determining "forced power off" shutdown5, 2000 ms is defined as the logic "Low" period. That is, in S504 in Fig. 5, if the period during which the logic of the power instruction signal 310s is "Low" exceeds 2000 ms, the power instruction from the operation unit 305 is determined to be a "forced power OFF" instruction. Also, if the defined signal pattern (first power saving state, reboot, power OFF) cannot be determined in any of S508, S509, and S510, the power instruction from the operation unit 305 is determined to be a "forced power OFF" instruction.

[0068] The signal patterns of the power instructions and the defined times for each power instruction described in this example are merely examples, and are not limited to these. The above is an explanation of an example of the definition of the signal pattern of the power instruction signal 310s corresponding to an instruction to switch the power state of the image forming apparatus 100.

[0069] As described above, in this embodiment, not only serial communication but also the power instruction signal line 310, which is a single signal line, is used to instruct a plurality of power states from the operation unit 305 to the control unit 300 (both). At this time, the logic of the power instruction signal 310s on the power instruction signal line 310, which is a single signal line, is changed based on a pattern defined in advance by the operation unit 305. By the control unit 300 determining the pattern of this signal, it becomes possible to appropriately switch between a plurality of power patterns even when an instruction cannot be given by serial communication (when the communication is not available, etc.). Therefore, in the past, only the forced power-off was possible when the serial communication was not available, but according to this embodiment, it becomes possible to appropriately switch the power state even in such a case. In addition, by adopting a simple configuration in which the operation unit 305 notifies the control unit 300 of a plurality of types of power instructions by a signal via the power instruction signal line 310, which is a single signal line, it is possible to prevent the control board and the like from becoming large and increasing in cost. In other words, it is possible to provide a device that can reliably switch the power state with a simple and inexpensive configuration.

[0070] Second Embodiment In the first embodiment, if an instruction cannot be received via serial communication, the power state is switched in the same manner as an instruction via serial communication according to the signal pattern of the power instruction signal 310s. In the second embodiment, even if an instruction via serial communication is possible, the final power mode is switched according to the signal pattern of the power instruction signal 310s thereafter. With this configuration, appropriate processing is possible even when it is necessary to further switch the power state due to an abnormality or the like after the power state is instructed via serial communication and the serial communication is terminated.

[0071] For example, when the operation unit 305 issues a "first power saving" instruction and the CPU 301 performs processing for power off, including the end of serial communication, in S411 of FIG. 4, an abnormality may occur in the data saving process within the operation unit 305, making it necessary to switch the power to OFF. In the case of the first embodiment, in such a situation, since the serial signal has already been cut off, it is necessary to once return from the "first power saving state" to the "standby state" and then to again instruct "power OFF" via serial communication. On the other hand, in the second embodiment, since an instruction can be given by the power instruction signal 310s even after the serial communication has been cut off, it is possible to switch the power state without once returning to the standby state. This will be described in detail below.

[0072] <Description of Control in Second Embodiment> The control content of the second embodiment will be described with reference to FIG. Fig. 7 is a flowchart showing an example of processing by the CPU 301 in the image forming apparatus of the second embodiment. The procedure of the processing shown in the flowchart of Fig. 7 is stored as a program in the ROM 303, and is realized by the CPU 301 reading and executing it. Note that since S701 to S707 in Fig. 7 are equivalent to the controls of S401 to S407 in Fig. 4, respectively, and S719 to S721 are equivalent to the controls of S416 to S418 in Fig. 4, respectively, description thereof will be omitted here.

[0073] The process from S707 onwards will be described below. First, a case where the power switch 313 is OFF in S707 will be described. If the state of the power switch 313 is OFF (Yes in S707), the CPU 301 advances the process to S708.

[0074] In step S708, the CPU 301 determines that a user instruction has been issued to transition to power OFF, and performs preparation processing in accordance with the instructed power state, equivalent to 411 in FIG. When the preparation process in S708 is completed, the CPU 301 checks whether the logic of the power instruction signal 310s is in the "Low" state (S709), which means that preparation for power interruption of the operation unit 305 is complete. The CPU 301 repeats the process of S709 until it checks that the logic of the power instruction signal 310s is "Low."

[0075] If the CPU 301 determines that the logic level of the power instruction signal 310s is "Low" (Yes in S709), the process proceeds to S710. In S710 and S711, the CPU 301 monitors for a predetermined time whether the logic of the power instruction signal 310s changes to "High" again in order to check whether a power instruction is issued by the power instruction signal 310s.

[0076] Then, if the logic level of the power instruction signal 310s becomes "High" within the predetermined time (Yes in S710), the CPU 301 determines that a power instruction is to be notified by the power instruction signal 310s, and proceeds to S713. The process of S713 will be described later.

[0077] If the CPU 301 determines that the logic of the power instruction signal 310s remains "Low" for a predetermined period of time or more (Yes in S711), it confirms the current power instruction and proceeds to S719. The processing from S719 onwards will be omitted as described above.

[0078] Next, a case where the power switch 313 is not OFF in S707 will be described. If the CPU 301 determines in S707 that the power switch 313 is not OFF (No in S707), the process proceeds to S712. In S712, the CPU 301 checks whether or not there is an instruction to switch the power state by serial communication. If it is determined that there is an instruction by serial communication (Yes in S712), the CPU 301 executes the above-mentioned process from S708.

[0079] On the other hand, if it is determined that there is no instruction through serial communication (No in S712), the CPU 301 advances the process to S713 described above. In S713, the CPU 301 checks whether the logic of the power instruction signal 310s is in the "Low" state. The "Low" state of the power instruction signal 310s here means that a power instruction has started by the power instruction signal 310s. If the logic of the power instruction signal 310s is not "Low" (No in S713), the CPU 301 returns the process to S705.

[0080] On the other hand, if it is determined that the logic of the power instruction signal 310s is "Low" (Yes in S713), the CPU 301 advances the process to S714. In S714, the CPU 301 performs a signal pattern determination process (FIG. 5) based on the detection time of the “Low” state of the power instruction signal.

[0081] When the CPU 301 finishes determining the signal pattern of the power instruction signal 310s in S714, the process proceeds to S715. In S715, the CPU 301 checks whether the power state instruction by the signal pattern is a "forced power OFF" instruction. If the CPU 301 determines that the power state instruction by the signal pattern is a "forced power OFF" instruction (Yes in S715), it performs power off processing (S719).

[0082] On the other hand, if the CPU 301 determines that the power state instruction based on the signal pattern is not an instruction to "force power OFF" (No in S715), the process proceeds to S716. In S716, the CPU 301 checks whether there is a difference between the power state instruction by the power instruction signal 310s and the power state instruction by serial communication received in S712. Here, a difference includes a case where a power instruction by serial communication has not been received and an instruction by the power instruction signal 310s is present. If the CPU 301 determines that there is no difference between the two power state instructions, that is, if the instruction by serial communication and the instruction by the power instruction signal 310s match (No in S716), it performs power off processing in accordance with the instruction (S719).

[0083] On the other hand, if the CPU 301 determines that there is a difference in the instruction contents (Yes in S716), the process proceeds to S717. In S717, the CPU 301 prioritizes the power state instruction by the power instruction signal 310s, switches the control content (performs preparation processing according to the power state according to the power instruction by the power instruction signal 310s), and proceeds to S718.

[0084] In S718, the CPU 301 monitors whether the logic of the power instruction signal 310s is in the "Low" state, which means that preparations for power-off of the operation unit 305 have been completed. The CPU 301 repeats the process of S718 until it confirms that the logic of the power instruction signal 310s is "Low." When the CPU 301 determines that the logic of the power instruction signal 310s is "Low" (Yes in S718), it proceeds to S719 and performs power-off processing (S719). The process from S719 onwards is the same as the process from S416 onwards in FIG. 4 as described above, and therefore a description thereof will be omitted here. This concludes the description of the control in the second embodiment.

[0085] In this embodiment, when the instruction by the serial communication and the instruction by the power instruction signal 310s are different, the instruction by the power instruction signal 310s is prioritized, but this is not limited to this. For example, the instruction given first between the serial communication and the power instruction signal 310s may be prioritized.

[0086] As described above, according to the second embodiment, even when instructions can be given through serial communication, it is possible to switch the final power mode according to the notification pattern of the subsequent power instruction signal 310s. This enables appropriate processing even when it is necessary to further switch the power state due to an abnormality or the like after instructing the power state through serial communication and terminating the serial communication.

[0087] In the above embodiments, the image forming apparatus is used for the description, but the present invention is not limited to the image forming apparatus. The present invention is applicable to various electronic devices having, for example, an instruction side that issues an instruction to switch the power state of the apparatus, and a switching side that switches the power state of the apparatus according to an instruction from the instruction side. The instruction side and the switching side are connected by a communication line (such as a serial communication line) that enables a predetermined communication, and a single signal line. The instruction side is configured to notify the switching side of an instruction to switch the power state of the apparatus by a predetermined communication via the communication line and each (both) of the patterns of the signal output to the signal line. Furthermore, the switching side is configured to be able to receive an instruction to switch the power state of the apparatus from the instruction side by a predetermined communication via the communication line and each (both) of the patterns of the signal input from the signal line.

[0088] As described above, in each embodiment, a configuration is provided in which an instruction to switch the power state is sent via each (both) of the serial communication line and the pattern of the signal flowing through a single signal line, and the instruction can be received via each of the lines. This makes it possible to provide an electronic device such as an image forming apparatus that can reliably switch the power state with an inexpensive configuration.

[0089] It goes without saying that the configurations and contents of the various data described above are not limited to those described above, and the data may have various configurations and contents depending on the application and purpose. Although one embodiment has been described above, the present invention can be embodied, for example, as a system, an apparatus, a method, a program, a storage medium, etc. Specifically, the present invention may be applied to a system composed of multiple devices, or may be applied to an apparatus composed of a single device. Furthermore, any combination of the above-described embodiments is also included in the present invention.

[0090] (Other embodiments) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions. Furthermore, the present invention may be applied to a system made up of a plurality of devices, or to an apparatus made up of a single device. The present invention is not limited to the above-mentioned embodiment, and various modifications (including organic combinations of the embodiments) are possible based on the spirit of the present invention, and are not excluded from the scope of the present invention. In other words, the present invention includes all configurations that combine the above-mentioned embodiments and their modifications. [Explanation of symbols]

[0091] 300 Control section 301 CPU 305 Operation section 309 Serial Communication Line 310 Power Indicator Signal Line 310s power indication signal

Claims

1. An electronic device capable of switching between a plurality of power states, an instruction unit capable of issuing a plurality of types of instructions for switching a power state of the electronic device; a control unit that switches a power state of the electronic device in accordance with the instruction from the instruction unit; a communication line connecting the instruction unit and the control unit for predetermined communication; a single signal line connecting the instruction unit and the control unit; the instruction unit notifies the control unit of the instruction by a predetermined communication via the communication line and a pattern of a signal output to the signal line; the control unit is capable of receiving the instruction from the instruction unit by a predetermined communication via the communication line and a pattern of a signal input from the signal line, the plurality of types of instructions are defined according to the elapsed time from when the signal flowing through the signal line becomes a predetermined logical value until when the signal changes to another logical value; The electronic device, wherein the signal pattern corresponds to the definition.

2. An electronic device capable of switching between multiple power states, an instruction unit capable of issuing a plurality of types of instructions for switching a power state of the electronic device; a control unit that switches a power state of the electronic device in accordance with the instruction from the instruction unit; a communication line connecting the instruction unit and the control unit for predetermined communication; a single signal line connecting the instruction unit and the control unit; the instruction unit notifies the control unit of the instruction by a predetermined communication via the communication line and a pattern of a signal output to the signal line; the control unit is capable of receiving the instruction from the instruction unit by a predetermined communication via the communication line and a pattern of a signal input from the signal line, the plurality of types of instructions are defined according to the number of times a logical value of a signal flowing through the signal line switches per predetermined time period; The electronic device, wherein the signal pattern corresponds to the definition.

3. The electronic device according to claim 1 or 2, characterized in that when a specified communication via the communication line is not possible, the control unit switches the power state of the electronic device in accordance with the instructions notified by the signal pattern input from the signal line.

4. The electronic device according to claim 3, characterized in that when the instruction notified by a specified communication via the communication line differs from the instruction notified by the pattern of the signal input from the signal line, the control unit switches the power state of the electronic device in accordance with the instruction notified by the pattern of the signal input from the signal line.

5. The electronic device according to claim 3, characterized in that when the instruction notified by a specified communication via the communication line differs from the instruction notified by the pattern of the signal input from the signal line, the control unit switches the power state of the electronic device in accordance with the instruction received first.

6. The electronic device according to any one of claims 3 to 5, characterized in that the control unit switches the power state of the electronic device in response to a change in the logical value of the signal input from the signal line after receiving the instruction through a specified communication via the communication line.

7. The control unit is after receiving the instruction by a predetermined communication via the communication line, a logical value of a signal input from the signal line is switched, and in response to the logical value of the signal not being switched again within a predetermined time, switching a power state of the electronic device; The electronic device according to claim 3 or 4, characterized in that after receiving the instruction through a specified communication via the communication line, the logical value of the signal input from the signal line switches, and if the logical value of the signal switches again within a specified time, the power state of the electronic device is switched in accordance with the instruction notified by the pattern of the signal input from the signal line thereafter.

8. 8. The electronic device according to claim 1, wherein the plurality of types of instructions include an instruction to put the electronic device into a power saving state.

9. 9. The electronic device according to claim 1, wherein the plurality of types of instructions includes an instruction to restart the electronic device.

10. 10. The electronic device according to claim 1, wherein the plurality of types of instructions includes an instruction to power off the electronic device.

11. The electronic device according to any one of claims 1 to 10, characterized in that the control unit forcibly turns off the power of the electronic device when the signal input from the signal line continues to have a predetermined logical value for a predetermined period of time or more.

12. 12. The electronic device according to claim 1, wherein the communication line is a serial communication line.

13. 13. The electronic device according to claim 1, wherein the electronic device is an image forming device.

Images