JP2007108608A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the reliability and stability in image quality adjustment control by maintaining image quality high in an image forming apparatus provided with an auxiliary power source. <P>SOLUTION: The image forming apparatus is provided with a main power source 42 and the auxiliary power source 43, which can store power and power is also supplied from the auxiliary power source, during a period when supply of power to load becomes high power, and power supply is stopped during a low power period. A control means 20 is provided in the image forming apparatus to carry out image quality adjustment during a period, when there is no switching between power supply/stop. When power supply/stop is switched during the image quality adjustment, the image quality adjustment is carried out again after the switching. When the image quality adjustment is started during the power supply, supplying of the power is continued, even when the power supply stopping condition is satisfied. When image adjustment start condition is satisfied during the power supply, power supply is stopped and image quality adjustment is carried out. Alternatively, when the image quality adjustment start condition is satisfied during the power supply, stopping timing for the power supply is determined, according to the remaining power in the auxiliary power source. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus having an auxiliary power source capable of storing electricity in addition to a main power source. More specifically, the present invention relates to an image forming apparatus that can supply power to a DC load by an auxiliary power source so that the power consumption does not exceed the power that can be supplied from the power supply line. It can be used for a copying machine, a facsimile machine, and an image processing complex machine combining these.

JP 2002-199588 A, and Japanese Patent Application Laid-Open No. 2004-236492.

  In recent years, copiers, printers, facsimiles using multifunctional electrophotographic processes, and multi-function machines that combine these have become multifunctional, and accordingly, the structure has become complicated and the maximum power consumption tends to increase. In order to reduce the factors of the image forming device itself and the waiting time of the operator, such as the waiting time until the fixing device rises and the temporary interruption of the operation due to the fixing temperature drop during the printing or copying operation, the power supplied to the fixing heater Tends to increase. On the other hand, since there is a limit to the power that can be supplied from a normal power supply line, this is a major limitation in designing the equipment.

  As disclosed in Patent Document 1, as a conventional technique for leveling load power, a means for monitoring the power supply of the main power supply is provided, and the power supply of the main power supply is less than a predetermined value. Technology that levels the power that changes sharply in a relatively short period of time by charging the auxiliary power supply and supplying the power stored in the auxiliary power supply when the power supplied to the main power supply exceeds a predetermined value. Is disclosed. Also, cited document 2 predicts the power consumption, and when the predicted power consumption exceeds the suppliable power of the main power supply, the auxiliary power supply can supply power to some loads and the maximum supply line can be supplied. There has been provided a power supply device that does not exceed electric power.

  However, according to the technique disclosed in the cited document 2, there is a voltage difference between the power supplied by the two power supply sources because the two power supply sources are switched in the power supply to some loads. When the power supply source is switched, voltage fluctuation occurs. This may affect various operations in the image forming apparatus. In the image forming apparatus, the image density is adjusted under a predetermined condition after printing a predetermined number of recording sheets or during the warm-up time at the time of start-up.When the power supply source is switched during this process, There is a concern that normal adjustment cannot be performed due to voltage fluctuation at the time of switching.

  The first object of the present invention is to maintain high image quality in image formation in an image forming apparatus equipped with an auxiliary power source, and to improve reliability and stability of image quality adjustment for maintaining high image quality. The second object is to improve the reliability and stability of image quality adjustment control for maintaining high image quality.

(1) A period including a main power supply device (42) and an auxiliary power supply device (43) capable of storing electricity, and supplying power stored in the auxiliary power supply device to the load during a period when the power supply to the load is high power. In the image forming apparatus that stops the power supply,
An image forming apparatus comprising: control means (20) for performing image quality adjustment for maintaining high image formation image quality during a period in which the power supply / stop of the auxiliary power supply to the load is not switched.

  In addition, in order to make an understanding easy, the code | symbol of the corresponding element or the corresponding matter of the Example which is shown in drawing and mentions later in a parenthesis was added as an example for reference. The same applies to the following.

  Image quality adjustment is performed to maintain high image formation image quality during periods when there is no switching between power supply / stop to the load of the auxiliary power supply device, so that the reliability and stability of image quality adjustment control is improved and the image quality adjustment is reliable. The image quality of image formation can be maintained high.

  (2) If the power supply / stop is switched during the image quality adjustment, the control means (20) adjusts the image quality again after the switching (S2, S12 in FIG. 5, S24c, s26c in FIG. 7). The image forming apparatus according to (1) above. According to this, even when the switching of power supply / stop to the load of the auxiliary power supply device and the success or failure of the image quality adjustment condition do not cooperate, image adjustment without the switching is realized, so the reliability and stability of the image quality adjustment control The image quality is improved, the reliability and stability of image quality adjustment is high, and the image quality of image formation can be kept high.

  (3) When the control means (20) starts the image quality adjustment during power supply from the auxiliary power supply to the load, a condition for stopping power supply from the auxiliary power supply to the load is satisfied during the image quality adjustment. Also, the power supply from the auxiliary power supply device to the load is continued, and the power supply from the auxiliary power supply device to the load is stopped after the image quality adjustment is completed (S44, S45 in FIG. 9, S40 in FIG. 8), (1) The image forming apparatus described in 1. According to this, since power supply from the auxiliary power supply to the load is continued during image quality adjustment, there is no change in load voltage switching, reliability and stability of image quality adjustment control is improved, and image quality adjustment reliability is improved. In addition, the stability is high, and the image quality of image formation can be kept high.

  (4) The control means (20) stops the power supply from the auxiliary power supply device to the load when the image forming apparatus reaches the start condition of the image quality adjustment during the power supply from the auxiliary power supply device to the load. The image forming apparatus according to (1), wherein image quality adjustment is performed (S51 to S54 in FIG. 11, S5b and S10b in FIG. 10). According to this, since the image quality adjustment is performed in a state where power supply from the auxiliary power supply to the load is stopped, there is no change in switching of the load voltage, the reliability and stability of the image quality adjustment control is improved, and the reliability of the image quality adjustment is improved. The image quality of image formation can be maintained high.

  (5) When the image forming apparatus reaches the image quality adjustment start condition during power feeding from the auxiliary power supply to the load, the control means (20) determines the image quality adjustment according to the remaining power of the auxiliary power supply. The timing at which power supply from the auxiliary power supply to the load is stopped is determined (S61 to S64 in FIG. 12, S5b and S10b in FIG. 10), and the image forming apparatus according to (1) above. According to this, after the power supply from the auxiliary power supply to the load is stopped if the remaining power is small, the image quality adjustment timing is determined during the power supply from the auxiliary power supply to the load if the remaining power is large, and the power is supplied to the load of the auxiliary power supply. The image quality adjustment can be performed during a period when there is no switching between power supply / stop.

  (6) When the remaining power is smaller than the power required for image quality adjustment, power supply from the auxiliary power supply to the load is stopped and image quality adjustment is performed. When the remaining power is larger, the image quality adjustment is performed and then the load is applied from the auxiliary power supply device. The image forming apparatus according to (5), wherein power supply to the power supply is stopped (S61 to S64 in FIG. 12, S5b and S10b in FIG. 10). According to this, there is no change in switching of the load voltage, the reliability and stability of image quality adjustment control is improved, the reliability and stability of image quality adjustment is high, and the image quality of image formation can be maintained high.

  (7) The auxiliary power supply (43) includes a charging means (43a) that charges and increases stored power while power supply from the auxiliary power supply to the load is stopped during the low power period. The image forming apparatus according to any one of (1) to (6) above. According to this, even if the instantaneous power consumption of the image forming apparatus is equal to or higher than the power that can be supplied from the power line, the power consumption of the image forming apparatus with respect to the power line can be leveled within the power that can be supplied from the power line.

(8) Image forming means for forming an electrostatic latent image on the photosensitive member (201), developing the electrostatic latent image into a toner image, and transferring the toner image directly or indirectly to a sheet via an intermediate transfer member (201-210);
A fixing device (214) including a fixing heater and fixing the toner image on the paper to the paper;
A main power supply device (42) including a fixing heater driving circuit (42b) for energizing the fixing heater and a main power supply circuit (42a) for supplying power to a power load other than the fixing heater;
An auxiliary power supply device (43) including a storage capacitor (43b), a charger (43a) for charging the storage capacitor, and a converter (43c) for outputting electric power of the storage capacitor;
A main power switch (40) interposed between a power line and the main power supply (42) and the auxiliary power supply (43); and
The control means (20) according to any one of (1) to (7), wherein power is supplied from the main power supply device (42);
An image forming apparatus comprising:

  (9) The control means (20) supplies power to the auxiliary power supply to the load at the time of starting up the fixing temperature of the fixing device (214) immediately after the operation voltage is applied to start the fixing device (214). The image forming apparatus according to (8), wherein the power supply of the auxiliary power supply to the load is stopped after starting up.

  (10) When the standby mode in which image formation can be started in response to an image formation start instruction continues for a set time without any input or operation by the user, the control means (20) activates the fixing heater drive circuit (42b). The image forming apparatus according to (8) or (9), wherein the image forming apparatus is switched to an energy saving mode in which a circuit unit that supplies power to a load required for image formation of the main power supply circuit (42a) is turned off.

  (11) After shifting to the energy saving mode, the control means (20) turns on the fixing heater driving circuit (42b) and forms an image of the main power supply circuit (42a) in response to a user input or operation. The image forming apparatus according to (10), wherein the apparatus returns to the standby mode in which a circuit unit that supplies power to a required load is turned on.

  (12) When the fixing temperature of the fixing device (214) is raised immediately after shifting to the standby mode, the control means (20) supplies power to the auxiliary power device to the load, and the fixing temperature is set. The image forming apparatus according to (11), wherein the power supply of the auxiliary power supply to the load is stopped after the startup.

  (13) The control means (20) charges the storage capacitor (43b) by the charger (43a) when the power supply of the auxiliary power supply to the load is stopped in the standby mode. The image forming apparatus according to (11) or (12).

  Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

  FIG. 1 shows the external appearance of a full-color digital multi-function copier MF1 according to the first embodiment of the present invention. The full-color copying machine MF1 is roughly constituted by units of an automatic document feeder (ADF) 120, an operation board 10, a color scanner 100, and a color printer 200. The operation board 10 and the color scanner 100 with the ADF 120 are units that can be separated from the printer 200, and the color scanner 100 includes a control board having a power device driver, sensor input, and controller. It communicates directly or indirectly with the engine controller to read the document image under timing control.

  FIG. 2 shows the mechanism of the color printer 200 of the multi-function copying machine MF1. The color printer 200 of this embodiment is a laser printer. The laser printer 200 includes four toner image forming units a to d for forming images of each color of magenta (M), cyan (C), yellow (Y), and black (black: K). They are arranged in this order along the moving direction of the transfer belt 208 (from left to right y in the figure). That is, it is a four-drum type (tandem type) full-color image forming apparatus. A neutralizing device, a cleaning device, a charging device 202 and a developing device 204 are arranged on the outer periphery of the photosensitive member 201 that is rotatably supported and rotates in the direction of the arrow. A space for storing optical information emitted from the exposure device 203 is secured between the charging device 202 and the developing device 204. There are four (a, b, c, d) photoconductors 201, but the image forming component configuration provided around each is the same. The color of the color material (toner) handled by the developing device 204 is different. A part of each photoconductor 201 (four) is in contact with the first transfer belt 208. A belt-like photoreceptor can also be employed.

  The first transfer belt 208 is supported and stretched between a rotating support roller and a driving roller so as to be movable in the direction of the arrow. The first transfer roller is located near the photoconductor 201 on the back side (inside the loop). Has been deployed. A cleaning device for the first transfer belt is disposed outside the belt loop. After the toner image is transferred from the first transfer belt 208 to the transfer paper (paper) or the second transfer belt 215, unnecessary toner remaining on the surface is wiped off. The exposure device 203 uses a known laser system to form an electrostatic latent image by irradiating the uniformly charged photoconductor surface with optical information corresponding to full-color image formation. An exposure apparatus comprising an LED array and an image forming means can also be employed.

  In FIG. 2, a second transfer belt 215 is disposed on the right side of the first transfer belt 208. The first transfer belt 208 and the second transfer belt 215 come into contact with each other to form a predetermined transfer nip. The second transfer belt 215 is supported and stretched between a support roller and a drive roller so as to be movable in the direction of the arrow, and a second transfer means is provided on the back side (inside the loop). A cleaning device, a charger, and the like for the second transfer belt are provided outside the belt loop. After the toner is transferred to the paper, the cleaning device wipes off the remaining unnecessary toner. The transfer paper (paper) is stored in the paper feed cassettes 209 and 210 in the lower part of the figure, and the uppermost paper is conveyed one by one by the paper feed roller to the registration roller 233 through a plurality of paper guides. Above the second transfer belt 215, a fixing device 214, a paper discharge guide 224, a paper discharge roller 225, and a paper discharge stack 226 are arranged. A storage unit 227 for storing replenishment toner is provided above the first transfer belt 208 and below the paper discharge stack 226. The toner has four colors, magenta, cyan, yellow, and black, and is in the form of a cartridge. The developing device 204 of the corresponding color is appropriately supplied by a powder pump or the like.

  Here, the operation of each unit during duplex printing will be described. First, image formation by the photoconductor 201 is performed. That is, by the operation of the exposure device 203, light from an LD light source (not shown) passes through an optical component (not shown), and among the photoconductors 201 uniformly charged by the charging device 202, the photoconductor of the image forming unit a. Then, a latent image corresponding to the writing information (information corresponding to the color) is formed. The latent image on the photoconductor 201 is developed by the developing device 204, and a visible image with toner is formed and held on the surface of the photoconductor 201. This toner image is transferred onto the surface of the first transfer belt 208 that moves in synchronization with the photoreceptor 201 by the first transfer means. The surface of the photoconductor 201 is cleaned by the cleaning device with the remaining toner, and is neutralized by the static eliminator to prepare for the next image forming cycle. The first transfer belt 208 carries the toner image transferred on the surface and moves in the direction of the arrow. A latent image corresponding to another color is written on the photoconductor 201 of the image forming unit b, and developed with a toner of the corresponding color to become a visible image. This image is overlaid on the visible image of the previous color already on the first transfer belt 208, and finally four colors are overlaid. In some cases, only monochrome black is formed. At this time, the second transfer belt 215 is moved in the direction of the arrow in synchronization, and the image formed on the surface of the first transfer belt 208 is transferred to the surface of the second transfer belt 215 by the action of the second transfer means 117. The The first and second transfer belts 208 and 215 are moved while the images are formed on the respective photosensitive members 201 of the four image forming units a to d in the so-called tandem format. Can be shortened. When the first transfer belt 208 moves to a predetermined position, a toner image to be created on another side of the paper is formed again by the photoconductor 201 in the process described above, and paper feeding is started. The uppermost sheet in the sheet feeding cassette 121 or 122 is pulled out and conveyed to the registration roller 233. The toner image on the surface of the first transfer belt 208 is transferred by the second transfer unit 117 to one side of the sheet fed between the first transfer belt 208 and the second transfer belt 215 via the registration roller 233. Further, the recording medium is conveyed upward, and the toner image on the surface of the second transfer belt 215 is transferred to the other surface of the sheet by the charger. At the time of transfer, the sheet is conveyed at a timing so that the position of the image is normal.

  The paper on which the toner images are transferred on both sides in the above steps is sent to the fixing device 214, and the toner images (both sides) on the paper are melted and fixed at one time. Are discharged to the paper discharge stack 226. As shown in FIG. 2, when the paper discharge units 224 to 226 are configured, the side (page) of the double-sided image that is later transferred to the paper, that is, the surface that is directly transferred from the first transfer belt 208 to the paper is the lower surface. Since the image is placed on the paper discharge stack 226, an image of the second page is created first and the toner image is held on the second transfer belt 215 in order to align the pages. The image is directly transferred from the first transfer belt 208 to the sheet. The image directly transferred from the first transfer belt 208 to the paper is a normal image on the surface of the photoconductor, and the toner image transferred from the second transfer belt 215 to the paper is a reverse image (mirror image) on the surface of the photoconductor. It is exposed as follows. Such image forming order for page alignment and image processing for switching between normal and reverse images (mirror images) are also performed by image data read / write control on the memory on the controller 501. After transfer from the second transfer belt 215 to the paper, a cleaning device including a brush roller, a collection roller, a blade, and the like removes unnecessary toner and paper dust remaining on the second transfer belt 215.

  In FIG. 2, the brush roller of the cleaning device for the second transfer belt 215 is in a state separated from the surface of the second transfer belt 215. The structure can swing around a fulcrum and can be brought into contact with and separated from the surface of the second transfer belt 215. Before the transfer onto the paper, the second transfer belt 215 is separated when carrying a toner image, and when cleaning is required, it is swung in the counterclockwise direction in FIG. The removed unnecessary toner is collected in a toner storage unit. The image forming process in the duplex printing mode in which the “duplex transfer mode” is set has been described above. In the case of duplex printing, printing is always performed by this image forming process.

  In the case of single-sided printing, there are two types of "single-sided transfer mode by the second transfer belt 215" and "single-sided transfer mode by the first transfer belt 208", and the single-sided transfer mode using the former second transfer belt 215 is set. In this case, a visible image formed in three colors, four colors, or monochromatic black on the first transfer belt 208 is transferred to the second transfer belt 215 and transferred to one side of the paper. There is no image transfer on the other side of the paper. In this case, there is a print screen on the upper surface of the printed paper discharged to the paper discharge stack 226. When the single-sided transfer mode using the latter first transfer belt 208 is set, a visible image formed in three colors, four colors, or single color black is transferred to the second transfer belt 215 on the first transfer belt 208. Instead, it is transferred to one side of the paper. There is no image transfer on the other side of the paper. In this case, there is a print screen on the lower surface of the printed paper discharged to the paper discharge stack 226.

  In FIG. 2, an optical sensor 220 is a reflective optical sensor composed of a light emitting element and a light receiving element, and the image density, the pitch of adjacent toner images, and the inclination of the toner image depending on the amount of reflected light from the detection target. Etc. are detected. The detection signal is referred to in image quality adjustment control described later.

  FIG. 3 shows an outline of the power supply system of the digital multifunction peripheral shown in FIG. An AC power supply voltage supplied from an AC line (commercial AC line) 41 via a main power switch 40 is converted into a DC voltage by an AC / DC converter 42a included in the main power supply 42, and some are directly + 24V and + 5V type. An operating voltage is applied to each of the loads 47b and 47c. The AC power supply voltage is also input to the capacitor charger 43a of the auxiliary power supply 43 and can be used for charging the capacitor 43b.

  The capacitor 43b of the auxiliary power source 43 is composed of a large capacity capacitor such as an electric double layer capacitor. In addition to the electric double layer capacitor, various selections can be made. In this embodiment, an electric double layer capacitor that can be charged and discharged in a short time and has a long life is used. As a characteristic of the electric double layer capacitor, the terminal voltage becomes lower as it is discharged, so that the output voltage is made constant by disposing the capacitor converter 43c after the capacitor 43b. The capacitor converter 43c uses any one of a boost converter, a step-down converter, and a step-up / down converter according to the charging voltage of the capacitor and the specification of the lower limit voltage for use.

  The switching circuit 46 controls the + 24V voltage generated by the AC / DC converter 42a based on the AC power supply voltage supplied from the AC line 41 and the + 24V voltage generated by the capacitor converter 43c from the power stored in the capacitor 43b. Switching is performed according to the switching instruction by 20 and supplied to the + 24V system load 47c.

  The control unit 20 also performs overall control of the digital copying machine 1 and operates the loads 47a to 47c sequentially according to each operation mode. The controller 20 also controls charging / discharging of the capacitor 43b. During the start-up of the device and for a period from the start-up to a predetermined time, the capacitor converter 43c generates power from H accumulated in the capacitor 43b. The switching circuit 46 is switched and operated so as to supply the + 24V power generated to the + 24V system load 47c. At this time, the margin generated with respect to the power supplied from the AC line 41 controls the fixing heater driving circuit 42b to increase the amount of power supplied to the fixing heating device 48.

  Next, the charge / discharge timing of the auxiliary power supply 43 will be described. FIG. 4 is a graph showing the transition of power consumption when the copying machine 1 is started up. The horizontal axis represents time, and the vertical axis represents the total power consumption of the apparatus. The dotted line is power that can be supplied from the AC line 41. In the fixing reload period I in which the fixing temperature is raised to the target temperature immediately after the main power switch 40 is turned on, in order to satisfy the starting time required for the apparatus, a larger amount of electric power than usual is supplied to the fixing heating apparatus 48, The fixing heating device 48 is raised as soon as possible to a temperature at which printing can be performed. Raising the fixing temperature to a temperature at which printing is possible is called fixing reload. At this time, power is supplied to the + 24V system load 47c by the auxiliary power supply 43, and a margin for the power that can be supplied from the AC line 41 can be supplied to the fixing heating device, thereby further shortening the startup time. Let

  In addition, in the period IIa from the start of the printing operation to the lapse of a predetermined time after the fixing reload (I), the power is supplied to the DC load by the auxiliary power source 43 as in the case of the start-up. Once the fixing heating device 48 reaches the temperature at which printing can be performed, even if the fixing heater supply power may be smaller than that at the start-up in order to maintain the temperature, after the fixing reload (I) is completed, When the printing operation is started, the DC load increases due to the start of the motor or the like, and the total power including the fixing heater supply power may exceed the power that can be supplied by the power supply line 41. The power supplied from the auxiliary power supply 43 becomes less than the power that can be supplied by the power supply from the auxiliary power supply 43, thereby preventing the system from failing. Also, at the start of printing, the fixing temperature drops due to the passage of paper, so in a system where it is necessary to increase the power to the fixing and heating device compared to the normal time, the auxiliary power supply 43 can be used to allow for the increase in power to the fixing and heating device. Power is supplied to the DC load. In other words, during the period when the power consumption of the copying machine exceeds the power that can be supplied from the power supply line 41, power can be supplied from the power supply line 41 to the DC load by the auxiliary power supply 43 and supplied from the AC line 41. It is assumed that the power is less than or equal to the power (dotted line in FIG. 4).

  Since the power stored in the auxiliary power source 43 is limited and cannot be continuously supplied, the power to the DC load is switched to be supplied from the main power source 42 when a predetermined time has elapsed. The power supply to the load from 43 is stopped. At this time, if the power supplied to the fixing heating device is set larger than normal, the power is returned to the normal power. Then, at the time of low power to end the printing operation and wait for the user's print instruction, if the stored power (capacitor voltage) of the auxiliary power supply 43 is slightly lower than the standby maintenance power (voltage threshold Vcw) or less, the capacitor voltage is The capacitor 43b is charged until the charge upper limit value is reached. If there is a print instruction during charging, charging of the capacitor 43b is stopped there.

  In the above description, the timing for stopping the power supply of the auxiliary power supply 43 to the load is set as a predetermined time, but it may be after the specified number of prints has elapsed. In this case, if the number of prints until the auxiliary power supply is stopped is determined as a variable value with parameters such as paper size and room temperature, the auxiliary power capacity can be utilized to the maximum.

  In addition, the fixing reload period I in which high power is required for the fixing heating device 48 and the period IIa from the time of fixing reloading until a predetermined time elapses have been described, but high power is supplied to the fixing heating device 48 even during other periods. If the specified period is necessary, power is similarly supplied from the auxiliary power supply 43 to the load.

  FIG. 5 shows that immediately after the operation voltage required for printing and copying is applied to each part of the copying machine 1 by switching the main power switch 40 from OFF to ON or returning from the energy saving mode to the standby mode. The outline of “power feeding control” PSCa started by the control unit 20 will be described. When a standby mode in which a required operating voltage is applied to each part of the copying machine 1 is entered, the control unit 20 turns on a switch that connects the voltage detection circuit 43d to the voltage detection terminal of the capacitor 43b, and the voltage detection circuit The level of the voltage detection signal 43d is read by A / D conversion, and it is determined whether it is equal to or higher than the charging start threshold value Vcw (step S0). The switch is turned off. That is, during a period when it is not necessary to grasp the capacitor voltage, the voltage detection circuit 43d is disconnected from the voltage detection terminal of the capacitor 43b to prevent the capacitor 43b from being discharged by the voltage detection circuit 43d.

  In the following, the word “step” is omitted from the parentheses, and step no. Write only the symbol.

  If the capacitor voltage read by A / D conversion is equal to or higher than the charging start threshold value Vcw, the control unit 20 grasps the state of each part of the copying machine (S1). Then, immediately after the main power switch 40 is turned on, or when returning from the energy saving mode to the standby mode (waiting for the print start instruction), it is determined that it is necessary to execute the fixing reload operation, that is, the fixing temperature rise. In this case, the capacitor converter 43c is driven, and the power supply to the + 24V system load 47c is switched to the power supply from the auxiliary power supply 43 by the switching circuit 46, and a register defined in one area of the memory inside the control unit 20 Information “1” indicating that power is being supplied from the auxiliary power supply 43 is written in FRp (S2). Further, the power that can be supplied to the fixing heating device 48 is increased (S3), and the fixing reload operation is started (S4).

  However, when the capacitor voltage read by A / D conversion is less than the charging start threshold value Vcw, the power supply from the auxiliary power source 43 is not performed, and the power that can be supplied to the fixing heating device 48 is not increased. Then, the fixing reload operation is started (S0, S4).

  The completion of the fixing reload is confirmed (S5). When the fixing reload is completed, the data in the register FRp is referred to (S6b). If it is “1” (power is being supplied from the auxiliary power supply 43), the auxiliary power supply The process proceeds to the print control (S6b to S12) in the state where the power supply is continued, and it is determined whether or not there is a print instruction by the operator (S6b).

  When there is a print instruction and it is necessary to switch the fixing supply power to the power during fixing reloading, the fixing supply power is switched to the power required at the start of printing (S7), and the auxiliary power supply 43 supplies the + 24V load 47c. The printing operation is started with the power supplied (S8). After starting the printing (imaging) operation, the timer is started (S9), and when it is confirmed that a predetermined time has passed (S10), that is, when the timer expires, the fixing supply power is switched to the supply power for normal printing. (S11) Subsequently, the switching circuit 46 switches the power supply to the + 24V system load 47c to the +24 power source generated by the AC / DC converter 42a of the main power source 42, and the capacitor converter 43 stops the operation (output), and the register Information “1” indicating that power is being supplied from the auxiliary power source of FRp to the load is cleared (S12). That is, the data in the register FRp is set to information “0” indicating that the power supply from the auxiliary power supply to the load is stopped. If there is no print instruction after the fixing reload, the fixing supply power is switched to the standby fixing temperature maintenance power at the timing when the fixing reload (fixing temperature rise) is completed (waiting for the print start instruction) (S11). ) The driving (voltage output) of the auxiliary power supply 43 is stopped, and the register FRp is cleared (S12).

  Thereafter, when there is a print instruction, a print operation is performed (S13, S14). Similarly, when the data in the register FRp is “0” (power supply from the auxiliary power supply 43 is stopped) immediately after the fixing reload is completed, the print control in the state where the power supply from the auxiliary power supply is stopped (S13). , S14) (S6a, S13).

  In the print control (S13, S14) in a state where power supply from the auxiliary power supply is stopped, power supply from the auxiliary power supply 43 is started as in steps S2 to S4 when the fixing temperature is drastically lowered during the printing operation. Then, the fixing temperature is rapidly raised, and when the fixing temperature rises, the power supply from the auxiliary power source 43 is stopped as in steps S11 and S12.

  Further, when there is no printing operation and waiting for a print instruction, the voltage of the capacitor 43 is read to search whether charging is required (S15), and if charging is required, the capacitor 43b is charged (S16). If there is no printing operation and the print instruction wait (standby mode) continues for the set time (S17), if the capacitor 43b does not need to be charged at this time, the mode shifts to the energy saving mode (S18). If the capacitor 43b is being charged when the standby mode continues for the set time, the charging mode is completed and the energy saving mode is entered. When shifting to the energy saving mode, the control unit 20 turns off the fixing heater driving circuit 42 and turns off the circuit unit of the AC / DC converter 42a that supplies power to a load required for image formation. In this energy saving mode, the control unit 20 is in a sleep state, and the user access monitoring circuit supplied with power from a part of the power supply circuit that is turned on also in the energy saving mode of the AC / DC converter 42a detects the user access and waits. The power is turned on to enter the mode, and the sleep state is continued until a steady operation voltage for image forming operation is applied to each unit. When shifting to the standby mode, that is, when a steady operation voltage is applied to each part of the copying machine, the control unit 20 wakes up and starts the above-described “power supply control” PSCa.

-Image quality adjustment control-
The control unit 20 executes image quality adjustment control in a standby mode in which the status of each part of the copier before and after step S1 is grasped and a print instruction is waited after the printing operation is completed. That is, the process proceeds to image quality adjustment control during the warm-up time at the start or immediately after printing a predetermined number of recording sheets, and image quality adjustment is performed when a predetermined condition is satisfied. In this embodiment, image quality adjustment includes density adjustment and image position adjustment. In any image quality adjustment, a toner image (toner patch) is formed on a primary transfer belt 208 as an image carrier. That is, when performing density adjustment and / or image position adjustment, a toner image 221 shown in FIG. 6 is formed on the transfer belt 208 at a predetermined timing separately from normal image formation.

  In the density adjustment (first adjustment step), first, each color image forming unit is operated to form each color toner image (a plurality of patch patterns for each color) on each photosensitive drum 201. Here, the formation of the toner image on the photosensitive drum 201 is performed by a charging process, an exposure process, and a development process. Next, the toner image formed on the photosensitive drum 201 is transferred onto the transfer belt 208 as shown in FIG. This is the toner image 221. Here, the toner images 221 as a plurality of patch patterns are ends of the transfer belt 208 in the width direction (the x direction orthogonal to the sub-scanning direction y in FIG. 6), and can be detected by the optical sensor 220. Is formed at the position. Further, the plurality of patch patterns (toner images 221) are formed by changing the developing bias so that the image density varies stepwise. The toner images 221 formed with different image densities sequentially pass through the position of the optical sensor 220 as the transfer belt 208 travels in the arrow direction y. Then, the image density of each toner image 221 is detected by the optical sensor 220.

  Here, the optical sensor 220 includes a light emitting element and a light receiving element, and detects the image density based on the amount of reflected light from the detection target (in this case, the toner image 221). Thereafter, the detection result by the optical sensor 220 is transmitted to the control unit 20. The control unit 20 obtains the relationship between the image density and the image forming conditions related to the image density based on the transmitted detection result. Specifically, a regression line indicating a change in image density when the developing bias is changed is obtained. Based on the obtained result, finally, an image forming condition for obtaining an optimum image density (target image density) is determined. Finally, based on the determined image forming condition, at least one of the developing bias, the charging potential, and the latent image potential is adjusted to a value that satisfies the determined image forming condition.

  In the image position adjustment (second adjustment step), first, each color image forming unit is operated to form a plurality of toner images for each color on the photosensitive drum 201. Here, the toner image formed on the photoconductive drum 201 is formed with a fixed developing bias, unlike the case of density adjustment. Note that, unlike the present embodiment, the toner image formed by image position adjustment has a finer pitch than that at the time of density adjustment, and a parallelogram pattern can be used in addition to a rectangular pattern. Furthermore, toner images can be formed on both ends of the transfer belt 208 in the width direction, and these toner images can be detected by the two optical sensors 220 provided on both ends. In that case, the adjustment amount of the skew adjustment motor is determined based on those results.

  Next, the toner image 221 formed on the photosensitive drum 201 is transferred onto the transfer belt 208. The plurality of toner images formed at equal intervals on the transfer belt 208 sequentially pass through the position of the optical sensor 220 as the transfer belt 208 travels in the arrow direction y. The optical sensor 220 detects each toner image, and the control unit 20 calculates the toner image distribution with reference to the toner image detection signal. More specifically, the positional deviation of the toner image on the transfer belt 208 is calculated by calculating the pitch between adjacent toner images, the inclination of the toner image, and the like. Then, based on the calculated misregistration, an image forming position on each photosensitive drum for obtaining an optimal image with no image misregistration is determined. Finally, based on the determined image forming position, at least one of the latent image writing timing on each photosensitive drum and the running timing of the transfer belt 208 is adjusted.

  Here, when both the above-described density adjustment (first adjustment process) and image position adjustment (second adjustment process) are performed, the image position adjustment is performed before the density adjustment. Further, during the period from image position adjustment to density adjustment, the developing device 204 is driven without stopping. This is for detecting the position of the toner image 221 formed by the image position adjustment, and the position adjustment is affected even if there is an image density variation due to the unstable developer in the developing device 204. By not doing. On the other hand, since the toner image 221 formed by the density adjustment determines the image forming condition based on the image density, the density adjustment is performed after the developer in the developing device 204 is sufficiently stabilized. It is necessary to do. In this embodiment, since the developing device 204 is operating during the image position adjustment control that is performed in advance, the toner charge amount and the toner concentration are sufficiently stable when the density adjustment control is started. become. As a result, a plurality of image quality adjustments are efficiently performed with high accuracy.

  FIG. 7 shows an outline of the “image quality adjustment control” IQCa executed by the control unit 20. When the control proceeds to image quality adjustment control (S21), the control unit 20 first executes startup (S22). That is, driving of the driving motor that drives the image forming unit such as the photosensitive drum 201 and the developing device 204 and the driving motor that drives the transfer belt 208 are started. Further, a charging voltage is applied to the charging unit 202 and a developing bias is applied to the developing roller. Thereafter, it is determined whether or not the image position adjustment start condition is satisfied (S23). Specifically, the output value of an in-machine temperature sensor (not shown) provided in the apparatus body 1 is read, and the difference (temperature difference ΔT) from the output value of the temperature sensor when the image position adjustment was performed last time is calculated. To do. When the temperature difference ΔT is greater than 5 ° C., that is, when the image position adjustment start condition is satisfied, the image position adjustment (S24a to 24c) is started.

  When image position adjustment is executed, the output value of the temperature sensor at that time is stored in the memory of the control unit 20. As a result, if it is determined in step S23 that image position adjustment is to be performed, first, a toner image 221 (image position detection pattern) is formed on the transfer belt 208 as described above with reference to FIG. Within S24b). Thereafter, the image forming position is adjusted according to the procedure described above (S24b).

  On the other hand, if it is determined in step S23 that image position adjustment is not performed, steps S24a to S24c are skipped. Next, it is determined whether or not the density adjustment execution condition is satisfied (S25). Specifically, when the detection value of the temperature sensor (thermistor sensor) that contacts the heating roller 230 in the fixing device 214 is 60 ° C. or less, that is, when the execution condition of the density adjustment control is satisfied, the density adjustment (S26a to S26c). ). As a result, a toner image 221 (density detection pattern) is formed on the transfer belt 208 (in S26b). Thereafter, the image forming density is adjusted according to the procedure described above (S26b).

  On the other hand, if it is determined in step S25 that the density adjustment is not performed, steps S26a to S26c are skipped. Finally, the fall is executed (S27). That is, the drive motor that drives the image forming unit and the transfer belt 208 is stopped. Further, the application of charging voltage and developing bias is stopped. Thus, this flow is finished (S28).

  By switching the DC power supply source during the image quality adjustment period (S2 and S12), there is a concern that poor image quality adjustment due to voltage fluctuation occurs. The cause of this poor image quality adjustment is that the output voltage of the high-voltage power supply fluctuates due to voltage fluctuations of the input voltage to the high-voltage power supply such as charging, development, and transfer, and the drive voltage of the motor that drives the image forming unit and transfer belt 208 As a result of motor rotation unevenness due to voltage fluctuations, normal pattern formation cannot be performed, resulting in poor image quality adjustment.

  The image quality adjustment as described above is executed when a predetermined condition is satisfied after a predetermined number of recording sheets are printed or during the warm-up time at the time of activation. In order to prevent image quality adjustment failure due to switching of the power supply source during image quality adjustment, in the first embodiment, the DC power supply source is switched at a predetermined timing of the image forming apparatus regardless of whether or not image quality adjustment is being performed. When switching is performed (S2 and S12 in FIG. 5) and the DC power supply source is switched during the image quality adjustment, the voltage fluctuation at the time of switching the power supply source is performed by performing the image quality adjustment again after the switching is completed. The image quality adjustment failure due to the image quality is prevented (S24a to S24c, S26a to S26c in FIG. 7).

  That is, referring to FIG. 7, when executing the “image position adjustment”, the control unit 20 first stores data (in the register FRp indicating the power supply switching state) in the register FRPp defined in one area of the memory inside the control unit ( S2 and S12) of FIG. 5 are written (S24a). That is, the power switching state information at the start time is saved. When the “image position adjustment” (S24b) is executed and finished, the data in the register FRp (S2, S12 in FIG. 5) indicating the power switching state at the time of completion is saved data in the register FRPp, ie, the image position adjustment If it coincides with the power supply switching state at the start, the power supply was not switched during the period of “image position adjustment” (S24b), so the process proceeds to the next step S25, but if it does not match, “image position adjustment” (S24b) Since there is a possibility that the power is switched during the period and the adjustment may be defective, the data of the register FRp is written again into the register FRPp (S24a), and the “image position adjustment” (S24b) is executed.

  Similarly, when executing “density adjustment”, the controller 20 first writes the data (S2 and S12 in FIG. 5) of the register FRp into the register FRPp (S26a), and then executes “density adjustment” (S26b). When this is finished, if the data in the register FRp (S2, S12 in FIG. 5) indicating the power switching state at the time of completion matches the saved data in the register FRPp, during the “density adjustment” (S26b) period. Since the power supply has not been switched, the process proceeds to the next step S27. However, if they do not match, the power supply is switched during the “density adjustment” (S26b) period, and the adjustment may be defective. Then, the data in the register FRp is written (S26a), and "density adjustment" (S26b) is executed.

The hardware of the second embodiment is the same as that of the first embodiment described above, but “power supply control” PSCb and “image quality adjustment control” IQCb executed by the control unit 20 of the second embodiment are the same as those of the first embodiment. It is a little different from the example (FIGS. 5 and 7). The “image quality adjustment control” IQCb of the second embodiment starts image quality adjustment (image position adjustment, density adjustment) on the condition that power is being supplied from the auxiliary power source 43 (FRp = 1). Switching of the power supply 43 to power supply stop is prohibited, and power supply from the auxiliary power supply 43 (FRp = 1) is maintained.

  FIG. 8 shows an outline of “feed control” PSCb executed by the control unit 20 of the second embodiment. This is obtained by inserting a progress stop step S40 between steps S5 and S6 of the “feed control” PSCa (FIG. 5) of the first embodiment. As a result, in the “power supply control” PSCb of the second embodiment, when the fixing reload is completed (S5), the data in the register FRq defined in one area of the memory inside the control unit instructs “1” to stop the progress. When the power is being supplied from the auxiliary power source and the image quality is being adjusted, the process proceeds to step S6b and subsequent steps (particularly, the power supply from the auxiliary power source in S12 is stopped), and the data in the register FRq permits the progress to be “0” ( The process waits for switching to “not in image quality adjustment”, and if switched, the process proceeds to step S6b and after (particularly, the power supply from the auxiliary power supply in S12 is stopped). When the process proceeds to image quality adjustment during power supply from the auxiliary power supply, the data in the register FRq is set to “1” in step S44 or S45 of FIG. 9 described later. However, when power supply from the auxiliary power supply is stopped, image quality adjustment is performed. The data in registers FRp and FRq are both “0”.

  When the fixing reload is completed or unnecessary, if the data in the register FRp is “0” (power supply from the auxiliary power supply is stopped), the process proceeds from step S40 to S6a, and then proceeds from S6a to step S13. Waiting for the end of adjustment (S44, S45 in FIG. 9, S40 in FIG. 8, S46 in FIG. 9, progress from S40 to S6a in FIG. 8) is not performed.

  FIG. 9 shows an outline of the “image quality adjustment control” IQCb executed by the control unit 20 of the second embodiment. When proceeding to the image quality adjustment control (S21), the control unit 20 of the second embodiment first determines whether there has been a switch from power supply stop from the auxiliary power supply (FRp = 0) to power supply from the auxiliary power supply (FRp = 1). If it is determined (S41, S42) and there is such a switching, the data in the register FRPp is rewritten to the data in the register FRp (S24a), and the capacitor voltage is equal to or higher than the threshold Vsw for switching the auxiliary power supply from power supply to stop. Then, start-up is executed (S22). Thereafter, it is determined whether or not the image position adjustment start condition is satisfied (S23). When the image position adjustment start condition is satisfied, “1” (power feeding from the auxiliary power source and image quality adjustment: progress stop instruction) is written in the register FRq (S44), and the image position adjustment (S24b) is executed. .

  On the other hand, if it is determined in step S23 that image position adjustment is not performed, steps S44 and S24b are skipped. Next, it is determined whether or not the density adjustment execution condition is satisfied (S25). When the execution condition of the density adjustment control is satisfied, “1” is written in the register FRq (S45), and the density adjustment (S26b) is executed.

  On the other hand, if it is determined in step S25 that no density adjustment is to be performed, steps S45 and S26b are skipped and a fall is executed (S27). That is, the drive motor that drives the image forming unit and the transfer belt 208 is stopped. Further, the application of charging voltage and developing bias is stopped. Finally, the data in the register FRq is cleared (S46). That is, the data in the register FRq is switched to “0” (not adjusting the image quality) that permits the progress. Thus, this flow is finished (S28).

  Thus, when the auxiliary power source is switched from the power supply stop state (FRp = 0) to the power supply state (FRp = 1) (for example, immediately after S2 in FIG. 8), the capacitor voltage is equal to or higher than the threshold value Vsw (S43), and the image When the position adjustment start condition or the density adjustment start condition is satisfied, the control unit 20 of the second embodiment writes “1” (progress stop instruction) in the register FRq (S44 / S45), and image position adjustment (S24b). ) Or density adjustment (S26b) is started. When the adjustment is completed, the data in the register FRq is rewritten to “0” (progress permission). In the “power supply control” PSCb, if the data in the register FRq is “1”, the process stays at Step S40 and does not proceed to Step S12. Therefore, during the image position adjustment (S24b) or the density adjustment (S26b), the auxiliary power Continues power supply and does not switch to power supply stop. When the image position adjustment (S24b) and the density adjustment (S26b) are completed, the data in the register FRq is switched to “0”. Therefore, the “power supply control” PSCb proceeds from step S40 to S6, and then in step S12. Switch to stopping power supply from the auxiliary power supply.

  As described above, in the second embodiment, when image quality adjustment is performed while DC power is being supplied from the auxiliary power source, switching is not performed even when a predetermined switching condition is reached, and switching processing is performed after image quality adjustment control is completed. By doing so, poor image quality adjustment due to voltage fluctuation at the time of switching the power supply source is prevented.

Since the input voltage (capacitor voltage) that can be output by the DC-DC converter 43c that converts the power from the auxiliary power supply 43 into predetermined DC power is limited, the time during which power can be supplied from the auxiliary power supply 43 is limited. . Therefore, in order to maintain the power supply from the auxiliary power supply 43 during the image quality adjustment, it is necessary to provide a margin for the power supply source switching condition for stopping the power supply from the state of the power supply from the auxiliary power supply 43. There is. Assuming that the capacitor voltage as the switching condition is Vsw [V], the output lower limit voltage of the DC-DC converter 43c is Vddcmin [V], the DC power consumption is Wdc [W], and the capacitor capacity is C [F], the capacitor voltage is The time t10 [s] from when the switching condition threshold Vsw is reached until the output of the DC-DC converter 43c becomes impossible is t10 = C {(Vsw) ² − (Vddcmin) ² } / 2Wdc [s]. Become. Assuming that the image quality adjustment time is 10 [s], the capacitor capacity is 43 [F], the output lower limit voltage Vddcmin of the DC-DC converter 43c is 18 [V], and the DC power consumption Wdc is 240 [W] From the equation, it is necessary to set the threshold value Vsw in step S43 to Vsw ≧ 20.87 [V].

  The hardware of the third embodiment is the same as that of the first embodiment described above, but “power supply control” PSCc and “image quality adjustment control” IQCc executed by the control unit 20 of the third embodiment are the same as those of the first embodiment. It is a little different from the example (FIGS. 5 and 7).

  FIG. 10 shows an outline of “power feeding control” PSCc executed by the control unit 20 of the third embodiment. This refers to whether there is a power supply stop instruction (FRs = 1: image quality adjustment required) from the auxiliary power supply in the fixing reload completion waiting loop (S5) and the predetermined time elapsed waiting loop (S10) of the first embodiment. When steps S5b and S10b are inserted and there is a power supply stop instruction (FRs = 1), a route for stopping power supply from the auxiliary power source in step S12 is formed via step S11. This is added in order to start and end image quality adjustment in a state where power supply from the auxiliary power supply is stopped.

  FIG. 11 shows an outline of the “image quality adjustment control” IQCc executed by the control unit 20 of the third embodiment. When the control proceeds to image quality adjustment control (S21), the control unit 20 of the third embodiment executes startup (S22). Thereafter, it is determined whether or not the image position adjustment start condition is satisfied (S23). When the image position adjustment start condition is satisfied, the image position adjustment control (S51 to S54, S24b) is executed. Here, first, referring to the data in the register FRp, if it is “0” (the auxiliary power supply stops supplying power), image position adjustment is performed (S51, S24b). However, if the data in the register FRp is “1” (auxiliary power is being supplied), “1” (instructed to stop power supply to the auxiliary power) is written in the register FRs (S51, S52). In "control" PSc, in response to the data "1" in step S5a or S10b, the process proceeds to step S11, and in step S12, the supply of power to the auxiliary power supply is stopped (S53), and the supply of power is stopped (FRp = 0). Then, the data in the register FRs is cleared to “0” (no stop instruction) (S54), and the image position is adjusted (S24b).

  On the other hand, if it is determined in step S23 that image position adjustment is not performed, steps S51 to S24b are skipped. Next, it is determined whether or not the density adjustment execution condition is satisfied (S25). When the density adjustment execution condition is satisfied, the density adjustment control (S55 to S58, S26b) is executed. Here, first, referring to the data in the register FRp, if it is “0” (the auxiliary power supply stops power supply), image position adjustment is performed (S55, S26b). However, if the data in the register FRp is “1” (auxiliary power is being supplied), “1” (instruction to stop power supply to the auxiliary power) is written to the register FRs (S55, S56). In “control” PSc, the process proceeds to step S11 in response to the data “1” in step S5a or S10b, and waits for the auxiliary power supply to be stopped in step S12 (S57), and the power supply is stopped (FRp = 0). Then, the data in the register FRs is cleared to “0” (no stop instruction) (S58), and image density adjustment is performed (S26b).

  On the other hand, if it is determined in step S25 that the density adjustment is not performed, steps S55 to S58 and S26b are skipped. Finally, the fall is executed (S27). That is, the drive motor that drives the image forming unit and the transfer belt 208 is stopped. Further, the application of charging voltage and developing bias is stopped. Thus, this flow is finished (S28).

  As described above, in the third embodiment, when the image quality adjustment start condition is satisfied while DC power is being supplied from the auxiliary power supply, the switching process (S5b) even if the switching condition for stopping power supply from the auxiliary power supply is not satisfied. / S10b-S11-S12), and image quality adjustment (S24b, S26b) is performed after switching. This prevents poor image quality adjustment due to voltage fluctuations during power supply source switching.

  The hardware of the fourth embodiment is the same as that of the first embodiment described above, but “power supply control” PSCc and “image quality adjustment control” IQCc executed by the control unit 20 of the fourth embodiment are the same as those of the first embodiment. It is a little different from the example (FIGS. 5 and 7). The content of “power supply control” executed by the control unit 20 of the fourth embodiment is the same as the content of “power supply control” PSCc shown in FIG. 10 of the third embodiment, and the image quality adjustment is in a state where power supply from the auxiliary power supply is stopped. Start and end with

  FIG. 12 shows an outline of the “image quality adjustment control” IQCd executed by the control unit 20 of the fourth embodiment. This “image quality adjustment control” IQCd is set to “image quality adjustment availability” between steps S51 and S52 in the image position adjustment controls S51 to S54 and S24b of the “image quality adjustment control” IQCc shown in FIG. 11 of the third embodiment. The determinations S61 and S62 are inserted, and the “image quality adjustment possibility determinations” S63 and S64 are inserted between steps S55 and S56 in the density adjustment controls S55 to S58 and S26b. The contents of the former “determination of image quality adjustment” S61, S62 and the latter “determination of image quality adjustment” S63, S64 are the same.

  The control unit 20 of the fourth embodiment establishes the image position adjustment start condition, starts the image position adjustment control (S51 to S54, S24b), and the data in the register FRp is “1” (the auxiliary power supply is supplying power). ), “Determining whether or not image quality adjustment is possible” S61 and S62 are performed. When it is determined as “No”, “1” (instruction to stop power supply to the auxiliary power supply) is written in the register FRs (S52). ) In “power supply control” PSc, in response to this data “1” in step S5a or S10b, the process proceeds to step S11 and waits for the auxiliary power supply to be stopped in step S12 (S53). = 0), the data in the register FRs is cleared to "0" (no stop instruction) (S54), and image position adjustment is performed (S24b). If the results of “determining whether image quality adjustment is possible” S61 and S62 are acceptable, image position adjustment is performed (S24b).

  On the other hand, if it is determined in step S23 that image position adjustment is not performed, steps S51 to S24b are skipped. Next, it is determined whether or not the density adjustment execution condition is satisfied (S25). When the density adjustment execution condition is satisfied, density adjustment control (S55 to S58, S26b) is started. If the data in the register FRp is “1” (auxiliary power is being supplied), “image quality adjustment” is performed. When “No” is determined and the determination is negative, “1” (instruction to stop power supply to the auxiliary power supply) is written in the register FRs (S56), and in the “power supply control” PSc, step S5a or In step S10b, in response to the data “1”, the process proceeds to step S11. In step S12, the power supply to the auxiliary power supply is stopped (S57). When the power supply is stopped (FRp = 0), the data in the register FRs is changed to “ It is cleared to “0” (no stop instruction) (S58), and image density adjustment is performed (S26b). If the results of “determining whether image quality adjustment is possible” S63, S64 are acceptable, image density adjustment is performed (S26b).

  On the other hand, if it is determined in step S25 that the density adjustment is not performed, steps S55 to S58 and S26b are skipped. Finally, the fall is executed (S27). That is, the drive motor that drives the image forming unit and the transfer belt 208 is stopped. Further, the application of charging voltage and developing bias is stopped. Thus, this flow is finished (S28).

  As described above, in the fourth embodiment, when the image forming apparatus reaches the image quality adjustment start condition while power is supplied from the auxiliary power supply, the image quality adjustment is performed in “determination of image quality adjustment availability” S61, S62 / S63, and S64. The switching timing of the DC power supply source is determined. That is, in the fourth embodiment, the timing for stopping the power supply from the auxiliary power source is determined after image quality adjustment when it is determined to be acceptable, and is determined before image quality adjustment when it is determined as no. This prevents poor image quality adjustment due to voltage fluctuations during power supply source switching.

  In the fourth embodiment, in “image quality adjustment feasibility determination” S61 and S63, the remaining power of the auxiliary power source is compared with a predetermined value, and “Yes” is determined if the remaining power is greater than or equal to a predetermined value. Then, image quality adjustment (S24b / S26b) is executed. If the remaining power is equal to or less than the predetermined value, “No” is determined, and image quality adjustment (S24b / S26b) is executed after power supply from the auxiliary power supply is stopped.

When starting “image quality adjustment feasibility determination” S61 and S63, the voltage of the capacitor 43b is Vl [V], the output possible lower limit voltage of the DC-DC converter 43c is Vddcmin [V], and the power consumption at the DC load is Wdc. [W] When the capacitor capacity is C [F], the time t10 [s] from the start of image quality adjustment until the output of the DC-DC converter 43c becomes impossible is t10 = C {(Vl) ² − (Vddcmin) ² } / 2Wdc [s]. The t10 [s] obtained from the above equation is compared with the image quality adjustment time tpc [s]. When t10 ≧ tpc, it is determined as “possible”, and when t10 <tpc, it is determined as “not”. .

It should be noted that the contents of “determining whether image quality adjustment is possible” S61 and S63 are “possible when the capacitor voltage is equal to or higher than the threshold value Vsw by comparing the capacitor voltage with the threshold value Vsw as in step S43 of the second embodiment. ”And“ No ”may be determined to be less than the threshold value Vsw. In this case, assuming that the capacitor voltage serving as the switching condition is Vsw [V], the output possible lower limit voltage of the DC-DC converter 43c is Vddcmin [V], the DC power consumption is Wdc [W], and the capacitor capacity is C [F]. The time t10 [s] from when the capacitor voltage reaches the switching condition threshold value Vsw until the DC-DC converter 43c becomes unable to output is t10 = C {(Vsw) ² − (Vddcmin) ² } / 2Wdc [ s]. Assuming that the image quality adjustment time is 10 [s], the capacitor capacity is 43 [F], the output lower limit voltage Vddcmin of the DC-DC converter 43c is 18 [V], and the DC power consumption Wdc is 240 [W] From the equation, the threshold value Vsw in step S43 is set to Vsw ≧ 20.87 [V].

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an outline of a mechanism of a multi-function copying machine MF1 equipped with a capacitor power supply device according to a first embodiment of the present invention. FIG. 2 is an enlarged vertical sectional view of the color printer 200 shown in FIG. 1. FIG. 2 is a block diagram showing an outline of a power supply system of the copying machine MF1 shown in FIG. 6 is a time chart showing an example of a change in power consumption after the main power switch 40 is switched from off to on in the copying machine MF1 shown in FIG. 4 is a flowchart showing an outline of power supply control including power supply / stop switching control of an auxiliary power supply 43 of the control unit 20 shown in FIG. 3. FIG. 3 is a plan view showing a toner patch pattern formed on a transfer belt 208 shown in FIG. 2 during image quality adjustment. 4 is a flowchart showing an outline of image quality adjustment control of the control unit 20 shown in FIG. 3. It is a flowchart which shows the outline | summary of the electric power feeding control including switching control of electric power feeding / stop of the auxiliary power supply 43 of the control part 20 of 2nd Example of this invention. It is a flowchart which shows the outline | summary of the image quality adjustment control of the control part 20 of 2nd Example of this invention. It is a flowchart which shows the outline | summary of electric power feeding control including switching control of electric power feeding / stop of the auxiliary power supply 43 of the control part 20 of 3rd Example of this invention. It is a flowchart which shows the outline | summary of the image quality adjustment control of the control part 20 of 3rd Example of this invention. It is a flowchart which shows the outline | summary of the image quality adjustment control of the control part 20 of 4th Example of this invention.

Explanation of symbols

201: Photoconductor 202: Charging device 203: Exposure device
204, 207: Developing device
208, 215: transfer belts 209 to 211: paper feed cassette 214: fixing device 224: paper discharge guide 225: paper discharge roller 226: paper discharge stack 227: replenishment toner storage 233: registration roller

Claims (7)

An image forming system comprising a main power supply device and an auxiliary power supply device capable of storing electricity, wherein the power stored in the auxiliary power supply device is supplied to the load during a period when the power supply to the load is high and the power supply is stopped during a period when the power is low In the device
An image forming apparatus comprising: control means for performing image quality adjustment for maintaining high image formation image quality during a period in which power supply / stop of the auxiliary power supply to the load is not switched.   The image forming apparatus according to claim 1, wherein when the power supply / stop is switched during the image quality adjustment, the control unit performs image quality adjustment again after the switching.   When the image quality adjustment is started during power supply from the auxiliary power supply to the load, the control means is controlled by the auxiliary power supply even if a condition for stopping power supply from the auxiliary power supply to the load is satisfied during the image quality adjustment. The image forming apparatus according to claim 1, wherein power supply to the load is continued and power supply from the auxiliary power supply to the load is stopped after the image quality adjustment is completed.   The control means performs image quality adjustment by stopping power supply from the auxiliary power supply device to the load when the image forming apparatus reaches the image quality adjustment start condition during power supply from the auxiliary power supply device to the load. The image forming apparatus according to claim 1.   When the image forming apparatus reaches the start condition of the image quality adjustment during power feeding from the auxiliary power supply to the load, the control means sends the auxiliary power supply to the load according to the remaining power of the auxiliary power supply. The image forming apparatus according to claim 1, wherein a timing for stopping the power feeding of the image forming apparatus is determined.   When the remaining power is smaller than the power required for image quality adjustment, power supply from the auxiliary power supply to the load is stopped and image quality adjustment is performed. When the remaining power is large, image quality adjustment is performed and then power is supplied from the auxiliary power supply to the load. The image forming apparatus according to claim 5, wherein the operation is stopped. 7. The auxiliary power device according to claim 1, further comprising charging means for charging and increasing stored power while power supply from the auxiliary power device to the load is stopped during the low power period. The image forming apparatus according to one.

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