JP6320018B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus having a power saving mode.

  An image forming apparatus having a conventional power saving mode includes a plurality of converters for converting an AC voltage of a commercial power source and outputting a DC voltage, and any one of the plurality of converters in a so-called power saving mode other than during image formation. A method for stopping the transmission is generally widely known. In addition, there is also known a method of reducing power during the power saving mode by performing rapid heating at the time of operation return without continuously heating the fixing heater at the time of the power saving mode by using the storage element (for example, Patent Document 1).

  Here, a method of stopping any of the plurality of converters in the power saving mode and an example of using a storage element as described in Patent Document 1 will be described with reference to FIG. In the image forming apparatus shown in FIG. 5, three DC voltages are generated by two isolated converters 705 and 706 and one constant current power source 710 via a rectifier 704 from an input of a commercial power source 701. A voltage detector 709 is connected to the constant current power source 710. The fixing heating device 703 is supplied with electric power from a fixing power source 702. In such an image forming apparatus, when shifting to the power saving mode, a stop signal from a control circuit (not shown) is received to save power by stopping generation of two DC voltages out of three DC voltages. . Further, in Patent Document 1, the capacitor charger 707 is charged by the capacitor charger 707 when shifting to the power saving mode, and the fixing heater is rapidly heated by supplementing the power supplied to the fixing heating device 703 when returning from the power saving mode. Achieving both power saving in the power saving mode.

  For example, as described in Patent Document 2, the power in the power saving mode is not from a commercial power source connected to the image forming apparatus, but from an external device such as a personal computer (hereinafter referred to as a PC) such as a LAN or USB. There is known a method of receiving a supply via a cable. Similarly, a method of receiving power supply from power generation means such as a solar cell attached to the image forming apparatus is also described.

JP 2010-217603 A JP 2007-047556 A

  However, in the conventional example having a plurality of converters, the image forming apparatus becomes large and expensive. Further, in the configuration in which a large amount of power for supplementing the power to the fixing heater as described in Patent Document 1 is supplied from the capacitor, the number and size of the necessary capacitors are increased, resulting in an increase in the size of the image forming apparatus. It becomes expensive. Furthermore, the method of supplying power from the capacitor has a problem that the loss of the capacitor also increases. In many cases, the image forming apparatus is used in an environment where power cannot be supplied from other than a commercial power source in the power saving mode. In a general office, a LAN connection rather than a USB connection is more prevalent, and there are few cases where the LAN has a power supply line at the present time. In addition, there are few cases where the image forming apparatus includes a power generation device or the image forming apparatus is connected to the power generation device. If the method described in Patent Document 2 is used in such a use environment, the energy stored in the power storage element is discharged when a print job is not received for a long time. In order to restart the image forming apparatus, it is necessary for the user to operate the power switch, which causes a problem that the convenience for the user is impaired. Also, recent image forming apparatuses are required to have a function that can respond to access from a user that occurs at an unpredictable timing because it is connected to an external device via a network even for power saving from the viewpoint of convenience. Yes.

  The present invention has been made under such circumstances, and an object thereof is to realize power saving without impairing user convenience.

  In order to solve the above-described problems, the present invention has the following configuration.

(1) from the AC voltage power supply for generating a DC voltage, the AC voltage supply provided to the power supply connection state, a first switch to cut off the supply to the power supply of the AC voltage in the non-connected state, the is charged by the generated DC voltage by the power supply includes a power storage device for supplying a DC voltage to the load, prior SL and control means for controlling the connection state or the disconnection state of the first switch, a second consumes predetermined power An image forming apparatus capable of operating in one mode and a second mode that consumes less power than the first mode, wherein the control unit shifts from the first mode to the second mode. when, the first switch off the supply of the AC voltage to the power supply as a non-connected state, after shifting to the second mode, starts charging of said power storage device by the DC voltage generated by the power supply Because the, on the basis of the operating state of the load, the image forming apparatus and determines the timing to the first switch connection state of the non-connected state.

  According to the present invention, power saving can be realized without impairing user convenience.

1 is a schematic diagram of an overall configuration of image forming apparatuses according to first to third embodiments and a diagram illustrating a power supply path from a commercial power source to a load according to the first embodiment. Flowchart for explaining processing after shifting to the power saving mode of the first embodiment The circuit diagram which measures the voltage of Example 2, the figure which shows the power supply path | route from the commercial power source of Example 3 to load, The graph which shows the voltage transition of the electrical storage element at the time of power saving mode Flowchart for explaining processing after shifting to the power saving mode according to the third embodiment. The figure which shows the circuit which has several converters and a capacitor of a prior art example

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail by way of examples with reference to the drawings.

[Image forming apparatus]
FIG. 1A is a cross-sectional view of an image forming apparatus (hereinafter referred to as a printer) 1 using an electrophotographic recording technique. When the print signal is generated, the scanner unit 21 emits a laser beam modulated according to the image information, and scans the photosensitive drum 19 charged to a predetermined polarity by the charging roller 16. As a result, an electrostatic latent image is formed on the photosensitive drum 19. During the image forming operation, the photosensitive drum 19 rotates in the counterclockwise direction (the arrow direction in the figure). Toner is supplied from the developing unit 17 to the electrostatic latent image formed on the photosensitive drum 19, and a toner image corresponding to image information is formed on the photosensitive drum 19. On the other hand, the recording material (recording paper) P loaded on the paper feed cassette 11 is fed one by one onto the conveyance path by the pickup roller 12 and conveyed toward the registration roller 14 by the roller 13. Further, the recording material P is conveyed from the registration roller 14 in accordance with the timing at which the toner image on the photosensitive drum 19 reaches the transfer nip formed by the photosensitive drum 19 and the transfer roller 20. The toner image on the photosensitive drum 19 is transferred to the recording material P while the recording material P passes through the transfer nip portion. Thereafter, the recording material P is heated by the image heating device 2 and the toner image is heated and fixed on the recording material P. The recording material P carrying the fixed toner image is discharged to a tray above the printer 1 by rollers 26 and 27.

  The cleaner 18 cleans the toner remaining on the photosensitive drum 19 after the transfer. The paper feed tray (manual feed tray) 28 has a pair of recording material regulating plates whose width can be adjusted in accordance with the size of the recording material P, and is provided to accommodate recording materials P of sizes other than the standard size. It has been. The pickup roller 29 feeds the recording material P from the paper feed tray 28 onto the transport path. The motor 30 drives the image heating device 2 and the like. The photosensitive drum 19, the charging roller 16, the scanner unit 21, the developing device 17, and the transfer roller 20 described above constitute an image forming unit that forms an unfixed image on the recording material P. The printer 1 according to the present exemplary embodiment operates in a normal mode that is a first mode that performs an image forming operation that consumes predetermined power, and a power saving mode that is a second mode that reduces power consumption compared to the normal mode. Can do. The image forming apparatus to which the present invention is applied is not limited to the printer 1 shown in FIG.

[Power supply path]
FIG. 1B schematically shows a power supply path from the commercial power supply 100 according to the present embodiment to the communication circuit 109 as a communication means. The commercial power supply 100 is connected to an isolated converter 104 that is a main power supply via a rectifier 103. The switch 102 that is the first switch is a switch for stopping or restarting the isolated converter 104 that is the main power source. Note that the switch 102 only needs to be connected to a position where the power supply to the isolated converter 104 can be controlled, and may be connected to either the front stage or the rear stage of the rectifier 103. The CPU 108 and the switch 102 constitute means for stopping or restarting the isolated converter 104 which is the main power source. The CPU 108 has a ROM, a RAM, and a timer (not shown). Further, the CPU 108 controls connection (ON) or disconnection (OFF) of the switch 102 as indicated by a broken line arrow in FIG.

  The isolated converter 104 is a power source that generates a DC voltage, and is connected to a drive circuit of the motor 30, a high voltage circuit (not shown), and the like, and is connected to a charging circuit 105 that is a charging unit. The storage element 106 is connected to the charging circuit 105 and is charged with an output controlled by the charging circuit 105. The power storage element 106 is also connected to a discharge circuit 107 serving as a discharge unit, and supplies power to the CPU 108 and the communication circuit 109 with an output controlled by the discharge circuit 107. The discharge circuit 107 can also have a function of measuring the voltage of the power storage element 106 and the current from the power storage element 106. The discharge circuit 107 is connected to a plurality of circuits as loads in addition to the CPU 108 and the communication circuit 109, and supplies power to the laser drive circuit 110, the sensor circuit 114, and the like, for example. In addition, the connection from the discharge circuit 107 to each load is performed through a switch that is a second switch. Specifically, the connection from the discharge circuit 107 to the communication circuit 109 is connected via the switch 111, the connection from the discharge circuit 107 to the laser drive circuit 110 is connected via the switch 112, and the connection from the discharge circuit 107 to the sensor circuit 114. Is performed via the switch 113.

  The CPU 108 is connected to the discharge circuit 107 without going through a switch. The CPU 108 controls connection (on) or disconnection (off) of the switches 111, 112, and 113. By connecting in this way, in an operation mode that does not require driving of each circuit constituting the load, the CPU 108 can turn off the switches 111, 112, and 113 to disconnect each load from the power supply path. . Note that the discharge circuit 107 outputs a voltage to the load connected by the CPU 108 and the switch even during the charging of the power storage element 106 by the charging circuit 105. That is, the discharge circuit 107 is always operating. Moreover, the load connected to the discharge circuit 107 is an example, and is not limited to the present embodiment.

[Charging operation in power saving mode]
FIG. 2A is a flowchart illustrating a charging operation after the printer 1 has shifted from the normal mode to the power saving mode. It is assumed that the printer 1 of this embodiment can be operated in three power saving modes with different power consumption. Here, three power saving modes are classified into power saving mode 1 (simply mode 1 in FIG. 2 (a)), power saving mode 2 (simply mode 2 in FIG. 2 (a)), and power saving mode 3 (FIG. 2 ( In a), it is simply referred to as mode 3).

  The power saving mode 1 is a mode in which the circuit group A is cut off (disconnected) when the printer 1 shifts to the power saving mode. For example, the circuit group A is a part of the communication circuit 109, the laser drive circuit 110, and the sensor circuit 114. When cutting off the circuit group A, the CPU 108 disconnects (turns off) the switch 111, the switch 112, and the switch 113. The reason why the sensor circuit 114 is blocked by the switch 113 is a part of the sensor circuit 114 for the following reason. For example, even in the power saving mode with the lowest power consumption, it is necessary to activate the minimum necessary sensors such as a sensor that detects that the power button is turned on or off.

  The power saving mode 2 is a mode in which the circuit group B is shut off when the printer 1 shifts to the power saving mode. For example, the circuit group B is a part of the laser drive circuit 110 and the sensor circuit 114. When cutting off the circuit group B, the CPU 108 disconnects (turns off) the switch 112 and the switch 113. The power saving mode 3 is a mode in which the circuit group C is shut off when the printer 1 shifts to the power saving mode. For example, the laser drive circuit 110 is assumed as the circuit group C. When cutting off the circuit group C, the CPU 108 disconnects (turns off) the switch 112. The number of power saving modes is not limited to the present embodiment and can be set arbitrarily. Further, which load is assigned to which group and which group is shut off in which power saving mode are not limited to the present embodiment, and are appropriately determined for each image forming apparatus.

  When the printer 1 shifts to the power saving mode, the CPU 108 executes processing after step (hereinafter referred to as S) 301. In S <b> 301, the CPU 108 determines which power saving mode is selected according to a user setting, a connection state of an external device, and the like, and determines that no power saving mode is selected. repeat. In S301, the CPU 108 proceeds to the process of S302 when the power saving mode 1 is selected, to the process of S303 when the power saving mode 2 is selected, and to the process of S304 when the power saving mode 3 is selected. In S302, since the CPU 108 has selected the power saving mode 1, the circuit group A is shut off. Specifically, the CPU 108 turns off the switches 111 to 113 and cuts off power supply to a part of the communication circuit 109, the laser drive circuit 110, and the sensor circuit 114. In step S303, the CPU 108 selects the power saving mode 2 and therefore shuts down the circuit group B. Specifically, the CPU 108 turns off the switches 112 and 113 and cuts off power supply to a part of the laser drive circuit 110 and the sensor circuit 114. Since the CPU 108 has selected the power saving mode 3 in S304, the circuit group C is shut off. Specifically, the CPU 108 turns off the switch 112 and cuts off the power supply to the laser drive circuit 110.

  In step S <b> 305, the CPU 108 stops the isolated converter 104 that is the main power supply by turning off the switch 102, and makes the power supply from the commercial power supply 100 almost zero. Note that the CPU 108 prohibits interruption of a print job. Further, the CPU 108 connects the electric power charged in the power storage element 106 by the discharge circuit 107 from the time when the isolated converter 104 is stopped in S305 to the time when the isolated converter 104 is restarted in S313 or S320 described later. Supplied to the load. Further, in S305, the CPU 108 starts a timer (not shown) in order to measure the elapsed time since the insulated converter 104 was stopped.

  In S <b> 306, the CPU 108 determines the operating state in order to determine the timing of starting charging of the power storage element 106. The determination of the operating state means that the CPU 108 turns on the switch 102 and instructs the restart of the isolated converter 104, and the energy that is predicted when the load is consumed before the charging of the power storage element 106 is started. This is an estimation process.

  Although there are various methods for estimating the energy consumed by the load, in this embodiment, the CPU 108 determines the power load level of the load connected to the discharge circuit 107 based on the operation state of the CPU 108 and the operation state of the communication circuit 109. Judging. Here, the operating state is, for example, the frequency at which the load operates. The power load level is a level indicating how much electrical energy is consumed by the load, and is also referred to as an operation level. The CPU 108 determines the operating state based on the power saving mode and the operation level. That is, the CPU 108 determines the energy required until the insulation type converter 104 is restarted by estimating which circuit is connected and how much power supply load the connected circuit is operating.

  The relationship between the power saving mode, the operation level, and the energy required for restarting is as shown in Table 1, for example. In Table 1, the power saving mode is represented by, for example, X, Y, and Z, and the operation level is represented by high, medium, and low.

例えば、ＣＰＵ１０８は、選択されている省電力モードがＹ、動作状態に基づいて判断した動作レベルが中である場合、絶縁型コンバータ１０４の再起動までに必要なエネルギーは０．５Ｗｓであると判断する。なお、Ｗｓは電力量の単位である。

For example, when the selected power saving mode is Y and the operation level determined based on the operation state is medium, the CPU 108 determines that the energy required for restarting the isolated converter 104 is 0.5 Ws. To do. Ws is a unit of electric energy.

  In this way, the CPU 108 determines the energy required before restarting, and determines the timing for starting charging so that the energy of the power storage element 106 does not run out before starting charging. Hereinafter, a parameter used by the CPU 108 to determine the timing of starting charging of the power storage element 106 is referred to as a charging start trigger. In the present embodiment, the charging start trigger will be described as an elapsed time after shifting to the power saving mode. More specifically, the elapsed time from when the isolated converter 104 serving as the main power supply is stopped in S305 is used as a charge start trigger.

  In S <b> 307, the CPU 108 determines a threshold for determining the charging start timing of the power storage element 106 based on the operating state determined in S <b> 306 (energy required until the main power supply is restarted). Here, when the charge start trigger is an elapsed time after the isolated converter 104 is stopped, the threshold becomes shorter as the energy required for restarting the isolated converter 104 is larger, and is necessary for the restart. The smaller the energy, the longer this threshold. As described above, the CPU 108 determines the operating state, so that even if a print job is not received, the battery 108 is recharged without using up the energy of the power storage element 106, and from a user who occurs at an unpredictable timing. It becomes possible to respond to access.

  In step S308, the CPU 108 checks whether a print job has been received. If the CPU 108 determines that a print job has been received (there is a print job), the process proceeds to step S320. In S320, the CPU 108 turns on the switch 102 to restart the isolated converter 104 in order to return from the power saving mode to the normal mode, and starts a print sequence in S321. Depending on the configuration of the printer 1 and the connection state of the external device, the same processing is performed when not only the print job but also power supply by the isolated converter 104 such as activation of the stapler is necessary. That is, in S320, the CPU 108 shifts from the power saving mode to the normal mode and restarts the isolated converter 104. When the CPU 108 returns from the power saving mode to the normal mode and the isolated converter 104 as the main power source is restarted, the charging circuit 105 charges the power storage element 106 until the power storage element 106 reaches a predetermined voltage. Do.

  If the CPU 108 confirms that no print job has been received (no print job) in S308, the process proceeds to S309. In step S309, the CPU 108 refers to a timer (not shown) started in step S305, and compares the elapsed time after stopping the isolated converter 104 with the threshold value determined in step S307. In step S <b> 309, the CPU 108 determines whether the elapsed time that is a charging start trigger is greater than a threshold value. If the CPU 108 determines in S309 that the elapsed time that is the charging start trigger is equal to or less than the threshold, the process returns to S308.

  If the CPU 108 determines in S309 that the elapsed time that is the charging start trigger is greater than the threshold, the CPU 108 determines that the energy of the power storage element 106 will be used up unless charging of the power storage element 106 is started, and proceeds to the process of S313. In step S313, the CPU 108 turns on the switch 102 and restarts the isolated converter 104. In S <b> 314, the CPU 108 permits interruption of the print job, and starts charging the power storage element 106 by the charging circuit 105 in S <b> 315. When the process returns to S315 from the process of S316 described later, the CPU 108 continues to charge the power storage element 106 by the charging circuit 105. In S <b> 316, the CPU 108 checks the amount of power stored in the power storage element 106. For example, the CPU 108 confirms the amount of power stored by detecting the voltage of the power storage element 106 using a voltage detection unit (not shown). Further, the CPU 108 may be configured to check the amount of stored electricity by detecting the integrated value of the current flowing from the charging circuit 105 by a detection unit (not shown). In the case where the charging circuit 105 is a constant current charging circuit, the CPU 108 may be configured to check the storage amount by measuring the time elapsed from the start of charging with a timer (not shown).

  In S316, the CPU 108 determines whether or not the amount of power stored in the power storage element 106 is greater than the predetermined amount. If the CPU 108 determines that the amount of stored power is equal to or less than the predetermined amount, the process returns to S315. If the CPU 108 determines in S316 that the charged amount is larger than the predetermined amount, the charging of the power storage element 106 by the charging circuit 105 is terminated in S317, and the process returns to S305. Here, the predetermined amount for the CPU 108 to determine the end of the charging of the power storage element 106 in S316 is a value determined by the withstand voltage of the power storage element 106, the efficiency characteristics, and the like, and the fact that the power storage element 106 has been charged. It is a value for judging.

  In step S <b> 314, the CPU 108 permits interruption by a print job while the power storage element 106 is being charged. For this reason, when an interrupt due to a print job occurs during charging of the storage element 106 by the charging circuit 105, the CPU 108 executes a print job interrupt process shown in FIG. If an interrupt due to a print job occurs, the CPU 108 activates a print sequence in S331 and recovers from the interrupt.

  As described above, according to the present embodiment, even in a small configuration using one isolated converter 104, the isolated converter 104 serving as the main power supply is stopped in the power saving mode, and the user requests from the power storage element 106. Supply power to respond to. Then, the CPU 108 determines the operating state, and maintains the state in which the isolated converter 104 can be restarted with the energy stored in the power storage element 106. That is, even when the image forming apparatus shifts to the power saving mode and does not receive a print job for a long time, the power storage element 106 can be charged at a timing according to the operating state. Thereby, according to the present Example, power saving can be implement | achieved, without impairing a user's convenience.

  In the first embodiment, an example in which the elapsed time after shifting to the power saving mode is used as the charging start trigger has been described. In the second embodiment, an example in which the voltage value of the power storage element 106 is used as a charge start trigger will be described. For example, when the discharge circuit 107 has a function for measuring the voltage of the power storage element 106, the voltage value of the power storage element 106 can be used as a charge start trigger. In addition, the same code | symbol is attached | subjected to the same structure as the structure demonstrated in Example 1, and description is abbreviate | omitted.

[Voltage measurement function of discharge circuit 107]
As shown in FIG. 3A, the voltage of the discharge circuit 107 is measured by dividing the potential of the positive electrode of the power storage element 106 with the resistor 121 and the resistor 122 serving as detection means and inputting them to the AD port of the CPU 108. The configuration. Thereby, the CPU 108 can easily measure the voltage value of the power storage element 106. The CPU 108 measures the voltage value of the power storage element 106 and determines the start of charging so that the energy of the power storage element 106 does not run out before starting charging. In this embodiment, the voltage value of the storage element 106 measured by the discharge circuit 107 is used as the charge start trigger. The CPU 108 performs the same processing as the processing up to S306 described with reference to FIG. 2 even when the voltage value of the power storage element 106 is used as the charging start trigger. Hereinafter, only processing different from the processing described above will be described.

ここで、ｅは表１の再起動までに必要なエネルギー［Ｗｓ］を示し、Ｓ３０６で求められた値である。また、Ｃは蓄電素子１０６の容量［Ｆ］を示し、予め既知の値である。ここでは、蓄電素子１０６としてキャパシタを例に説明するが、その他、電池などの蓄電素子でもよい。 [Charging operation]
In S <b> 307, the CPU 108 calculates a voltage value (ν (V)) serving as a threshold value for the charging start trigger based on the table shown in Table 1. In addition, the equation for calculating the voltage that is the threshold value for the charge start trigger from the table in Table 1 is Equation 1 below.

Here, e indicates energy [Ws] required until the restart in Table 1, and is the value obtained in S306. C indicates the capacity [F] of the power storage element 106, which is a known value in advance. Here, a capacitor is described as an example of the power storage element 106, but a power storage element such as a battery may be used.

  The process of S308 in FIG. 2 is the same as that in the first embodiment, and a description thereof will be omitted. The process of S309 will be described. The processing of S309 in FIG. 2 is read as “charging start trigger <threshold?” In the present embodiment. In S309, the CPU 108 determines whether or not the voltage value of the power storage element 106 measured by the discharge circuit 107 is lower than the voltage value (ν) that is the threshold value of the charging start trigger calculated by Equation 1 in S307. If the CPU 108 determines in step S309 that the voltage value of the storage element 106 measured by the discharge circuit 107 is equal to or greater than the threshold value, the process returns to step S308. In S309, if the CPU 108 determines that the voltage value of the power storage element 106 measured by the discharge circuit 107 is lower than the threshold value, the CPU 108 determines that the energy of the power storage element 106 will be used up unless charging of the power storage element 106 is started. Proceed to processing. In step S <b> 313, the CPU 108 restarts the isolated converter 104 by turning on the switch 102. The other processes are the same as the processes described in the first embodiment, and a description thereof will be omitted.

  As described above, according to the present embodiment, it is possible to realize power saving without impairing user convenience.

  FIG. 3B shows a schematic diagram of a power supply path from the commercial power supply 100 according to the third embodiment to the communication circuit 109, which is a communication unit. The circuit diagram of this embodiment is obtained by adding a voltage detection circuit 101 which is an AC voltage detection means for detecting the AC voltage of the commercial power supply 100 to the circuit of FIG. About another structure, it is the same as that of FIG.1 (b), attaches | subjects the same code | symbol and abbreviate | omits description. FIG. 4 is a flowchart showing the charging operation after shifting to the power saving mode of this embodiment. In the present embodiment, when the CPU 108 determines in S309 that the charge start trigger is equal to or less than the threshold value, the process returns to the process in S306, and the other processes are the same as in FIG. Description is omitted. Further, the overall configuration of the image forming apparatus 1 is the same as that described with reference to FIG. In this embodiment, an example in which a method of measuring the voltage of the power storage element 106 by the discharge circuit 107 and measuring the voltage of the commercial power supply 100 by the voltage detection circuit 101 will be described with reference to FIGS. . The charge start trigger may be in accordance with either Example 1 (elapsed time since the main power supply is stopped) or Example 2 (voltage value of the storage element).

[Charging operation]
As in the first embodiment, the CPU 108 shifts to any one of the power saving modes in the processes of S301 to S304, and stops the isolated converter 104 that is the main power source in S305. In S <b> 306, the CPU 108 performs processing for estimating the operating state, that is, the energy consumed by the load. In this embodiment, as will be described below, the energy of the load (reactivation) that is predicted until the charging of the electric storage element 106 corresponding to Table 1 used in Embodiments 1 and 2 is started. The accuracy of estimation of energy required by the time is improved. Here, the energy required for restarting the isolated converter 104 is expressed by the following equation 2.

  Here, E is the energy [Ws] required until restart, s is the time taken to restart the isolated converter 104 (hereinafter referred to as restart time) [s], and W1 is the power consumption in the corresponding operating state. [W]. W1 is, for example, the difference between the energy obtained from the voltage value of the electricity storage element 106 measured at a certain time in a certain operating state and the energy obtained from the voltage value of the electricity storage element 106 measured at a predetermined time. To do. W2 is a time average value [W] of energy that depends on the restart time s among the energy required for restart, and is measured in advance and stored in a memory (not shown), for example. To do. Further, e1 is energy [Ws] that does not depend on the restart time s among the energy required for restart, and is, for example, energy lost in proportion to the resistance value of the power storage element 106. It is assumed that it is stored in

  In this embodiment, the voltage detection circuit 101 detects the voltage value of the commercial power supply 100 as a result of detection by the voltage detection circuit 101. For this reason, the starting time of the isolated converter 104 which is a main power supply can be obtained with high accuracy. That is, the CPU 108 can accurately calculate the restart time s of the isolated converter 104 by detecting the voltage value of the commercial power supply 100 by the voltage detection circuit 101. Moreover, since the efficiency of the isolated converter 104 also varies depending on the voltage value of the commercial power supply 100, the accuracy of the time average value W2 of the energy that depends on the restart time s among the energy required for restart increases. Further, when the discharge circuit 107 is configured to detect the voltage value of the power storage element 106, the voltage value of the power storage element 106 can be detected by the discharge circuit 107, and thus the accuracy of the power consumption W1 in the operating state is increased. In S306, the CPU 108 obtains the energy E required until the restart according to Equation 2, and determines the threshold value for the charging start trigger in S307. Since the process of S308 has been described in the first embodiment, a description thereof will be omitted.

  CPU108 can grasp | ascertain the change of the voltage value of the electrical storage element 106 like FIG.3 (c) by repeating the process of S306-S309 (No). Here, in FIG. 3C, the horizontal axis is time (t), the vertical axis is the voltage value (v) of the storage element 106 detected by the discharge circuit 107, the solid line is large when W1 is large, and the broken line is small in W1. It is a graph which shows time. From FIG. 3C, it can be seen that the voltage value of the power storage element 106 becomes 0 V faster when W1 is larger than when W1 is small. That is, it can be seen that the amount of power stored in the power storage element 106 is consumed faster as the power consumption increases. Here, Formula 1 can be transformed into a formula for obtaining the energy e of the power storage element 106. Since the voltage value of the storage element 106 can be detected by the discharge circuit 107, the accuracy of W1 is increased by measuring the voltage value of the storage element 106 and substituting it into ν. Note that although an example in which the voltage of the power storage element 106 is measured is described in this embodiment, the output power can also be measured by measuring the output current from the power storage element 106.

  As described above, in this embodiment, the accuracy of estimating the energy required before restarting is increased, so that the isolated converter 104 can be compared with the case where only the table 1 is used for checking the operating state as in the first embodiment. It is possible to reduce the frequency of restarts. On the other hand, in this embodiment, the circuit scale is increased by adding the voltage detection circuit 101 of the commercial power supply 100 to the first embodiment. For this reason, the circuit configuration may be selected in view of the required accuracy and the influence of the circuit scale.

  As described above, in this embodiment, even in a small configuration using a single isolated converter 104, the isolated converter 104 is stopped in the power saving mode, and power for responding to a user request from the power storage element 106 is obtained. It is the structure which supplies. Then, the CPU 108 determines the operating state, and performs control so as to maintain a state in which the insulating converter can be restarted with the energy stored in the power storage element 106. Thereby, according to the present Example, power saving can be implement | achieved, without impairing a user's convenience.

104 Insulating converter 105 Charging circuit 106 Storage element 107 Discharging circuit 108 CPU

Claims (10)

A power source that generates a DC voltage from the AC voltage;
The AC voltage supply provided to the power supply connection state, a first switch to cut off the supply to the power supply of the AC voltage in the non-connected state,
A storage element that is charged by a DC voltage generated by the power source and supplies the DC voltage to a load ;
And control means for controlling the connection state or the disconnection state before Symbol first switch,
With
An image forming apparatus capable of operating in a first mode that consumes predetermined power and a second mode that consumes less power than the first mode,
The control means includes
When shifting from the first mode to the second mode, the supply of the AC voltage to the power supply is cut off with the first switch in a disconnected state ,
After the transition to the second mode, to start charging of said power storage device by the DC voltage generated by the power supply, based on the operation state of the load, and the first switch unconnected connection state An image forming apparatus that determines a timing to perform. The said control means judges the timing which makes a said 1st switch a connection state based on the operating state of the said load, and the elapsed time after shifting to said 2nd mode. The image forming apparatus according to 1. Comprising a detecting means for detecting the voltage of the electric storage element;
2. The control unit, according to claim 1 , wherein a timing for setting the first switch to a connection state is determined based on an operating state of the load and a voltage of the power storage element detected by the detection unit. The image forming apparatus described in 1. Wherein, by determining the energy which the power is consumed by the load until the restart is stopped, any one of claims 1 to 3, characterized in that to determine the operating status of the load 2. The image forming apparatus according to item 1. AC voltage detecting means for detecting the AC voltage,
Wherein the control means is further based on the result of detecting by the AC voltage detecting means, the image forming apparatus according to claim 4, characterized in that to determine the operating status of the load. Wherein when the storage amount of the electric storage device reaches a predetermined amount, and ends the charging of said power storage device, according to claim 1 to 5, characterized in that said first switch disconnected The image forming apparatus according to any one of the above. Wherein, in the transition to the second mode, either before of the plurality of modes power consumption different Kimake load, according to claim 1 to 6, characterized in that the process proceeds to either one mode The image forming apparatus according to claim 1. The load has a plurality of circuits;
Comprising a plurality of second switches to the respective connection state or non-connected state of said plurality of circuits and the power storage element,
The image forming apparatus according to claim 7 , wherein the control unit controls a connection state or a non-connection state of the plurality of second switches when shifting to any one of the modes. The control unit allows an interrupt of a print job when the first switch is connected to start charging the power storage element while operating in the second mode. the image forming apparatus according to any one of 8. Image forming means for forming an image on a recording material,
The first mode is a mode in which image formation is performed by the image forming unit,
The second mode, the image forming apparatus according to any one of claims 1 to 9, characterized in that in the power saving mode to shift after the image formation has passed a predetermined exit time by said image forming means .

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