JP5677100B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a heating device that heats a toner image on a recording material and an image forming apparatus such as a copying machine, a laser printer, and a facsimile machine that includes the heating device that heats the recording material.

  Conventionally, a heating apparatus of an image forming apparatus has been proposed that uses an induction heating method to enable high-speed printing, and uses a thin heating roller to shorten the warm-up time (see, for example, Patent Document 1). ).

  Also, a conventional image forming apparatus has been proposed in which the cassette heater is turned off while the main body is turned off or on standby or while a predetermined motor is being driven so as not to exceed the upper limit of power consumption (for example, Patent Document 2). reference).

JP 2005-345990 A JP-A-10-228143

  Some image forming apparatuses (high-speed machines) capable of forming images at high speed employ an electromagnetic induction heating type fixing device in order to efficiently increase the temperature of the fixing device.

  In addition, image forming apparatuses that perform high-speed processing are also required to reduce the warm-up time of the fixing unit. For this reason, the temperature rise is accelerated by reducing the heat capacity by thinning the fixing roller. Since such a thin fixing roller has a low heat storage capability, the temperature is likely to decrease due to paper passing.

  On the other hand, since the upper limit of power consumption is determined in the image forming apparatus, the power that can be supplied to the fixing device is limited. Therefore, in the image forming apparatus, in order to prevent a fixing failure due to a temperature drop during paper feeding, the temperature of the fixing device is constantly monitored, and when the detected temperature exceeds a certain condition, control is performed so as to enter a productivity reduction sequence. doing.

  However, in such an image forming apparatus, the conditions for determining whether or not to enter the productivity reduction sequence are the type of paper, the usage environment, the time from power ON, and the like. For this reason, in the image forming apparatus, when thick paper is used, or when conditions such as use in a cold place overlap, control to enter the productivity reduction sequence is frequently performed, and the work efficiency decreases. there were.

  An object of the present invention is to provide an image forming apparatus capable of reducing the number of transitions to a productivity reduction sequence and suppressing a reduction in work efficiency.

In order to achieve the above object, an image forming apparatus of the present invention includes a plurality of cassettes that store transfer materials, and an image forming unit that forms toner images on transfer materials fed from any of the plurality of cassettes. A fixing device for fixing the toner image on the transfer material by heat treatment , a fixing heating means for heating the fixing device, and a transfer material heating arranged to heat the transfer material stored in the plurality of cassettes. And a function for controlling the power supplied to the fixing heating means, and a function for controlling the power supplied to the transfer material heating means , wherein the power supplied to the fixing heating means is less than or equal to a predetermined power. is by supplying power to the transfer material heating means in response, a power control means for controlling so as to heat the transfer material, said fixing heating means the whole of the fixing device from reaching the fixing temperature heating When the image formation is performed until the temperature is stabilized at the fixing temperature, the transfer material stored in the cassette that is heated most by the transfer material heating unit is preferentially selected. a cassette selection control means for controlling to feed paper, and characterized by comprising a.

  According to the present invention, when image formation is performed by the image forming apparatus, the number of transitions to the productivity reduction sequence can be reduced, and reduction in work efficiency can be suppressed.

1 is a schematic configuration explanatory diagram showing an overall configuration of an electrophotographic color copying machine according to a first embodiment of the present invention. FIG. 2 is a schematic configuration explanatory diagram showing a configuration of a fixing unit and its control system in the electrophotographic color copying machine according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram showing a relationship between power supplied to a fixing unit and cassette heater control in the electrophotographic color copying machine according to the first embodiment of the present invention. 3 is a flowchart showing a procedure of productivity deterioration sequence shift determination processing in the electrophotographic color copying machine according to the first embodiment of the present invention. 3 is a flowchart showing a procedure of cassette heater control processing in the electrophotographic color copying machine according to the first embodiment of the present invention. 3 is a flowchart showing a procedure of cassette selection processing in the electrophotographic color copying machine according to the first embodiment of the present invention. It is a flowchart which shows the procedure of the process of the cassette selection control 1 when the paper of the same size is loaded in each cassette in the electrophotographic color copying machine according to the second embodiment of the present invention. 6 is a flowchart showing a procedure of cassette selection control when sheets of a plurality of sizes are stacked on each cassette in the electrophotographic color copying machine according to the second embodiment of the present invention.

(First embodiment)
The electrophotographic color copying machine according to the first embodiment of the image forming apparatus of the present invention will be described below with reference to FIGS. The electrophotographic color copying machine according to the first embodiment is configured as a color image output apparatus in which a plurality of image forming units are arranged in parallel and an intermediate transfer system is adopted, to which the present invention can be preferably applied.

  FIG. 1 is a schematic configuration explanatory view showing the overall configuration of the electrophotographic color copying machine of FIG. 1, wherein 1 is an electrophotographic color copying machine main body. The electrophotographic color copying machine main body 1 is configured by disposing an image output unit 1P below the image reading unit 1R. The image reading unit 1R optically reads a document image, converts it into an electrical signal, and transmits it to the image output unit 1P.

  The image output unit 1P includes a plurality of image forming units 10 (10a, 10b, 10c, 10d) arranged in parallel in the present embodiment, a paper feeding unit 20, an intermediate transfer unit 30, and a fixing unit 40. And have. The image output unit 1P further includes a cleaning unit 50, a photo sensor 60, and a control unit 70.

Next, each unit in the image output unit 1P will be described in detail.

Each image forming unit 10 (10a, 10b, 10c, 10d) of the image output unit 1P has the same structure. In each of the image forming units 10a to 10d, a photosensitive drum 11 (11a, 11b, 11c, 11d), which is a drum-shaped electrophotographic photosensitive member as a first image carrier, is rotationally driven in the direction of the arrow. It is attached to.

  A primary charger 12 (12a, 12b, 12c, 12d) and an optical system 13 (13a, 13b, 13c, 13d) are arranged in order in the rotational direction facing the outer peripheral surfaces of the respective photosensitive drums 11a to 11d. Has been placed. Following this, the folding mirror 16 (16a, 16b, 16c, 16d), the developing device 14 (14a, 14b, 14c, 14d) and the cleaning device 15 (15a, 15b, 15c, 15d) are arranged.

  The primary charger 12 (12a, 12b, 12c, 12d) applies a uniform charge amount to the surfaces of the photosensitive drums 11a to 11d, respectively. Further, the optical system 13 (13a, 13b, 13c, 13d) performs an exposure process using a light beam such as a laser beam that is modulated in accordance with the recording image signal from the recording image signal output unit 1R. In the optical system 13 (13a, 13b, 13c, 13d), the photosensitive drums 11a to 11d are irradiated with light beams modulated in accordance with the recording image signal and exposed through the folding mirrors 16a to 16d. An electrostatic latent image is formed.

  The electrostatic latent images formed on the photosensitive drums 11a to 11d are respectively developed by developing devices 14a to 14d that develop with four color developers (hereinafter referred to as “toner”) such as yellow, cyan, magenta, and black. Visualized.

  The visible images visualized on the respective photosensitive drums 11a to 11d are belt-shaped intermediate transfer members as second image carriers that constitute the intermediate transfer unit 30 with the image transfer regions Ta, Tb, Tc, and Td. Are transferred onto the intermediate transfer belt 31. The intermediate transfer unit 30 will be described in detail later.

  Each of the photosensitive drums 11a to 11d is cleaned by the cleaning devices 15a, 15b, 15c, and 15d in which the toner remaining on the surface without being transferred to the intermediate transfer member is disposed on the downstream side of the image transfer regions Ta to Td. It is scraped off and cleaned.

  In the image output unit 1P, the above-described process is repeated, so that image formation with each color toner is sequentially performed.

  A paper feed unit 20 is disposed inside the image output unit 1P. The sheet feeding unit 20 includes cassettes 21a, 21b, 21c, and 21d for storing the transfer material P, and pickup rollers 22a, 22b, 22c, and 22d for feeding the transfer material P from the cassettes 21a to 21d one by one. Is provided.

  Further, the paper feed unit 20 includes a paper feed roller pair 23 for forming a transport path for transporting the transfer material P fed from the pickup rollers 22 a to 22 d to the fixing unit 40, and a paper feed guide 24. Prepare. In the sheet feeding unit 20, conveyance paths having different distances from the cassettes 21 a to 21 d to the fixing unit 40 are configured.

  The paper feeding unit 20 includes a registration roller 25 for feeding the transfer material P to the secondary transfer region Te in accordance with the image forming timing of each image forming unit. At the same time, the paper feeding unit 20 includes cassette heaters 26a and 26b which are transfer material heating means configured to be able to heat the transfer material P in each of the cassettes 21a to 21d.

  Next, the intermediate transfer unit 30 for transferring the toner image formed on the photosensitive drum 11 (11a, 11b, 11c, 11d) onto the transfer material P supplied from the paper supply unit 20 will be described in detail. .

  The intermediate transfer unit 30 includes an intermediate transfer belt 31 that is wound around a driving roller 32, a driven roller 33, and a secondary transfer counter roller 34. The intermediate transfer belt 31 is made of, for example, PET (polyethylene terephthalate), PVdF (polyvinylidene fluoride), or the like. The drive roller 32 is configured to coat the surface of the metal roller with rubber (urethane or chloroprene) having a thickness of several millimeters to prevent slippage with the belt.

  The driving roller 32 is driven to rotate by a DC brushless motor (not shown), thereby transmitting a driving force to the intermediate transfer belt 31 and moving it in an endless track shape. Further, the driven roller 33 has a function as a tension roller that applies an appropriate tension to the intermediate transfer belt 31 by a biasing force of a spring (not shown) while rotating following the rotation of the intermediate transfer belt 31.

  Further, the intermediate transfer unit 30 is configured such that the portion of the intermediate transfer belt 31 wound between the driving roller 32 and the driven roller 33 becomes the primary transfer plane A.

  In the intermediate transfer unit 30, primary transfer chargers 35 (35 a to 35 d) are provided on the back of the intermediate transfer belt 31 in the primary transfer regions Ta to Td where the photosensitive drums 11 a to 11 d and the intermediate transfer belt 31 face each other. Has been placed.

  On the other hand, in the intermediate transfer unit 30, a secondary transfer roller 36 is disposed to face the secondary transfer counter roller 34, and the intermediate transfer belt 31 and the transfer material P are nipped between them to perform secondary transfer. A secondary transfer region Te is formed. Therefore, the secondary transfer roller 36 is configured to come into pressure contact with the intermediate transfer belt 31 with an appropriate pressure.

  A cleaning unit 50 for cleaning the image forming surface of the intermediate transfer belt 31 is disposed downstream of the secondary transfer region Te of the intermediate transfer belt 31. The cleaning unit 50 includes a cleaning blade 51 for removing toner on the intermediate transfer belt 31 and a waste toner box 52 for storing waste toner.

  In the image output unit 1P, the fixing unit 40 is disposed on the downstream side in the conveyance direction of the transfer material P from the position where the secondary transfer counter roller 34 and the secondary transfer roller 36 are disposed.

  The fixing unit 40 is configured to press the pressure roller 404 (408) against the fixing roller 403 (407). In the fixing unit 40, a guide 43 for guiding the transfer material P to the nip portion of the roller pair 403, 404 (407, 408) is disposed.

  The image output unit 1P includes an inner discharge roller 44 and an outer discharge roller for guiding the transfer material P discharged from the roller pair 403, 404 (407, 408) of the fixing unit 40 to the outside of the apparatus. 45 is arranged.

  Further, the image output unit 1P includes a paper discharge tray 48 on which the transfer material P sent to the outside of the apparatus main body by the external paper discharge roller 45 is placed.

  Next, the main part of the temperature control system for reducing the temperature drop when the fixing device is fed in the electrophotographic color copying machine main body 1 will be described with reference to FIG.

  The electrophotographic color copying machine main body 1 includes a control unit 70 that is power control means for controlling internal devices for temperature adjustment for reducing a temperature drop when the fixing device passes. Although not shown, the control unit 70 includes a CPU, a registration correction circuit, a motor driver unit, and the like.

  As shown in FIG. 1, the control unit 70 that is a power control means is configured to be able to drive and control by transmitting a control signal to the heating power supply unit 80. The heating power supply unit 80 controls the amount of power supplied to the cassette heaters 26a and 26b, which are transfer material heating means arranged to be able to heat the recording paper 411 on the paper supply unit 20 in accordance with a control signal from the control unit 70. Then, the heating operation is performed.

  Further, the control unit 70 that is a power control unit is configured to be able to drive control by transmitting a control signal to the fixing power source 415. The fixing power source 415 controls the amount of electric power supplied to a heating device 412 that is a fixing heating unit arranged to perform a heating process in a state of being pressed against the fixing unit 40 in accordance with a control signal from the control unit 70. To perform the heating operation.

  When the control unit 70 controls the heating device 412 via the fixing power source 415, the entire fixing device is set to a predetermined fixing temperature according to the detection value of the temperature detection sensor 414 arranged for detecting the temperature of the fixing unit 40. It is configured to control the temperature.

  Next, details of the fixing unit 40 will be described with reference to FIG.

  The fixing unit 40 heats and presses the recording paper 411 while sandwiching and transporting the recording paper 411 between a pair of upper and lower belt transport mechanisms, and heats and presses the unfixed toner image on the recording paper 411 (transfer). It is configured to be fixed on the material.

  The belt conveying mechanism on the upper side in FIG. 2 of the fixing unit 40 allows the fixing belt 405 that is an endless belt between the driving fixing roller 403 and the driven fixing roller 407 to have a constant tension. It is constructed over a stretch. The driving fixing roller 403 is rotationally driven by a driving motor 401. The driven fixing roller 407 is mounted so as to apply tension to the wound belt 405 and be supported rotatably.

  The lower belt conveying mechanism of the fixing unit 40 in FIG. 2 is such that a constant tension acts on the fixing belt 406 that is an endless belt between the driving fixing roller 404 and the driven fixing roller 408. It is configured to wrap around. The driving fixing roller 404 is rotationally driven by a driving motor 402. The driven fixing roller 408 is mounted so as to apply tension to the wound belt 405 and be supported rotatably.

  Each of the belt 405 and the belt 406 is configured by forming a surface layer of silicone rubber on a metal (for example, Ni). Further, each of the pressure rollers 404 and 408 is driven by the motor 401 or 402, respectively, but may be configured to be driven by a motor or the like via a gear or the like.

  In the fixing unit 40, the upper belt conveyance mechanism in FIG. 2 and the lower belt conveyance mechanism in FIG. 2 are configured to press the belt 405 and the belt 406 against each other. For this reason, the driving fixing roller 403 and the driving fixing roller 404 are mounted so as to be biased in a direction in which they are pressed against each other via the belt 405 and the belt 406. At the same time, the driven fixing roller 407 and the driven fixing roller 408 are mounted so as to be biased in a direction in which they are pressed against each other via the belt 405 and the belt 406.

  Further, in the fixing unit 40, the motor 402 and the motor 401 are controlled to be driven to rotate in the directions of arrows in FIG.

  As a result, the belt transmission mechanism formed by winding the belt 405 around one of the driving fixing roller 403 and the driven fixing roller 407 that hits the upper side in FIG. 2 is illustrated by the driving force of the driving fixing roller 403. It is driven to rotate in the direction of the arrow 2. Along with this, a belt transmission mechanism formed by winding the belt 406 around the other driving fixing roller 404 and the driven fixing roller 408 which is the lower side in FIG. 2 is illustrated by the driving force of the driving fixing roller 404. It is driven to rotate in the direction of the arrow 2.

  In the fixing unit 40 configured as described above, the portion where the belt 405 and the belt 406 are in pressure contact with each other performs an operation of moving in the direction of the arrow A synchronously, thereby conveying the recording paper 411 sandwiched therebetween.

  Further, in this fixing unit 40, pressure pads 409 and 410 are arranged in a portion where the belt 405 and the belt 406 are in pressure contact with each other between the driving fixing rollers 403 and 404 and the driven fixing rollers 407 and 408. Has been.

  In the fixing unit 40, one pressure pad 409 is disposed to face the inner surface of the belt 405, and the other pressure pad 410 is disposed to face the inner surface of the belt 406. The pressurizing pads 409 and 410 arranged in this way are urged in directions approaching each other via the belt 405 and the belt 406. With this configuration, the recording paper 411 sandwiched between the belt 405 and the belt 406 can be planarly sandwiched by the pressing pads 409 and 410 with a predetermined urging force.

  Further, the fixing unit 40 is configured such that a heating device 412 that is a fixing heating unit is disposed above the fixing roller 407 so that the belt 405 is locally heated. The heating device 412 serving as the fixing heating means is configured by, for example, an electromagnetic induction heating method, and generates a magnetic field by causing an alternating current to flow through the arranged coil, thereby causing the belt 405 serving as a conductive heating element to self-heat. Let A temperature detection sensor 414 composed of, for example, a thermistor is disposed on the downstream side in the moving direction of the belt 405 from the heating position of the heating device 412 so as to detect the surface temperature of the belt 405. The detected temperature detected by the temperature detection sensor 414 is transmitted to the control unit 70.

  The control unit 70, which is a power control unit, controls the amount of power supplied from the fixing power source 415 to the heating device 412 while driving the fixing unit 40 to rotate the belt 405. As a result, the portion of the belt 405 heated by the heating device 412 heats the fixing roller 407, the driving fixing roller 403, the pressure pad 409, and the belt 406 that are in direct contact therewith. At the same time, the heat energy of the belt 405 heated by the heating device 412 is conducted to the fixing roller 408, the driving fixing roller 404 and the pressure pad 410 that are in contact with each other via the belt 406 and heated. In this way, the heat energy caused by the heating device 412 partially heating the belt 405 is conducted and diffused throughout the fixing unit 40. Then, after a lapse of a certain time, the entire fixing unit 40 is in a stable temperature control state at a predetermined fixing temperature that is uniformly heated.

  The control unit 70 controls the heating device 412 to supply, for example, a maximum power amount of 1200 W at startup (warm-up) immediately after power-on, 900 W during image formation (printing), and 500 W during standby. . In this control, the power supply at startup is maximized to reach the specified temperature in the shortest possible time from a low temperature, and the power supply during standby is reduced to keep the temperature of the fuser alone. To do. In the control unit 70, the power supply amount is changed depending on conditions such as the heat capacity of the fixing device and the image forming speed.

  In the fixing unit 40, as a safety device for the heating device 412, a thermo switch 413 is disposed in contact with the inside of the belt 405 located near the heating device 412. The thermo switch 413 is configured to cut off the power supply to the fixing unit 40 when the temperature of the contact portion with the belt 405 exceeds 250 ° C., for example.

  In the fixing unit 40 configured as described above, a recording sheet 411 on which an unfixed toner image is placed is inserted between the belt 405 and the belt 406. Then, the recording paper 411 on which the unfixed toner image is placed is moved in the direction of the arrow A while being sandwiched between the belt 405 and the belt 406, and the recording paper is subjected to a heat treatment in a state where the toner image is pressed. It is fixed on 411 (on the transfer material).

  Next, control of electric power supplied to the heating device 412 of the fixing unit 40, which is a fixing device configured as shown in FIG. 2, will be described with reference to FIG. FIG. 3 shows the transition of the detected temperature of the fixing device and the power supply to the fixing device at the start-up (warm-up), standby and printing operations.

  A control unit 70 for controlling the fixing unit 40 controls the amount of power to the heating device 412 while detecting the temperature of the temperature detection sensor 414. That is, the control unit 70 constantly supplies 1200 W to the heating device 412 during the warm-up of the fixing unit 40, transitions to a standby state when the temperature exceeds a predetermined temperature (for example, 190 ° C.), and reduces the supply power amount to 500W.

  In the fixing unit 40, when the printing operation is started, the recording material is deprived of heat when the recording paper passes through the fixing device, so that the temperature of the fixing unit 40 decreases. For this reason, when the temperature detection sensor 414 detects that the temperature of the belt 405 and the belt 406 has decreased to a predetermined temperature (190 ° C.) or less, the control unit 70 increases the supplied power to 900 W. Thereafter, the control unit 70 performs control so that the supplied power is lowered to 500 W again when the fixing device reaches a predetermined temperature or higher. In this way, the control unit 70 controls the fixing unit 40 to be kept at a predetermined temperature by switching the supply power in accordance with the detected temperature detected by the temperature detection sensor 414.

  Here, in the electrophotographic color copying machine including the fixing unit 40, there is an upper limit on the current that can be consumed from the power outlet. For example, in the case of Japan, since the current obtained from a general outlet is 15 A, the upper limit power that can be consumed is determined for the entire copying machine.

  Here, if the upper limit of the power that can be consumed by the entire copying machine is 1500 W, it is necessary to supply 300 W to other power such as the drive systems of the motors 401 and 402 during the warm-up, and the upper limit that can be supplied to the fixing device. Limited to 1200W.

  When this copier is on standby, 500 W is consumed for the fixing device and 300 W is consumed for other power, so there is a margin of 700 W.

  When this copying machine performs printing, the number of motors that are driven to carry the transfer material and the like increases, so the other power consumption increases to 600 W. Further, at the time of printing, since 900 W is supplied to the fixing unit 40 when the temperature of the fixing unit 40 becomes a predetermined temperature or lower, the power consumption becomes an upper limit of 1500 W. Here, when the temperature of the fixing unit 40 becomes equal to or higher than a predetermined temperature, only 500 W may be supplied to the fixing unit 40. Therefore, in this case, only the power consumption 500 W of the fixing unit 40 and the other power consumption 600 W are consumed, so that there is a margin of 400 W before the upper limit of the power consumption.

  Next, the operation of the above-described electrophotographic color copying machine will be described.

  In this electrophotographic color copying machine, a user operates an operation unit (not shown) to input a command for image formation. Then, the control unit having a CPU (not shown) that has received the command signal in the electrophotographic color copying machine issues an image forming operation start signal, and is selected based on the selected paper size and other commands. Starts the paper feeding operation.

  Here, when the control unit controls the paper feeding operation to feed paper from the upper paper feed stage, as shown in FIG. 1, first, the transfer material P is picked up from the cassette 21a one by one by the pickup roller 22a. Send it out to the transport path. Further, the controller drives the pair of paper feed rollers 23 to transport the transfer material P while guiding the transfer material P so as to pass between the paper feed guides 24 in the transport path. Then, the control unit stops when the transfer material P reaches the position where the transfer material P is conveyed to the registration roller pair 25 on the conveyance path and the leading edge of the transfer material P hits the nip portion of the registration roller pair 25 that is stopped. Control as follows.

  Next, the control unit controls the image forming unit to start an image forming operation at a timing when the photo sensor 60 detects a mark (not shown) written in the intermediate transfer belt 31. At the same time, the control unit starts the rotation of the registration roller pair 25 in accordance with the mark detection timing. The rotation start timing is set so that the transfer material P and the toner image primarily transferred from the image forming unit onto the intermediate transfer belt 31 coincide in the secondary transfer region Te. The intermediate transfer belt 31 may be provided with a plurality of marks.

  Next, when receiving the mark detection signal of the photosensor 60, the control unit issues an image forming operation start signal (ITOP) to the image forming unit to form a toner image on the photosensitive drum by the above-described process. . Next, the control unit primary-transfers the toner image formed on the photosensitive drum 11d on the upstream side in the rotation direction of the intermediate transfer belt 31 onto the intermediate transfer belt 31 in the primary transfer region Td by the primary transfer charger 35d. Transfer.

  Next, the control unit conveys the primary transferred toner image to the next primary transfer region Tc, aligns the resist on the previous toner image, and transfers the next toner image. The control unit controls each image forming unit to execute the image forming process with a delay in accordance with the timing at which the toner image formed on the intermediate transfer belt 31 is conveyed.

  The control unit performs the primary transfer of the four color toner images onto the intermediate transfer belt 31 by controlling so that the above-described operation process is repeated in the remaining image forming units.

  Next, the control unit conveys the transfer material P to the secondary transfer region Te so as to be in contact with the intermediate transfer belt 31, and applies a high voltage to the secondary transfer roller 36 in accordance with the passing timing of the transfer material P. Control to do. As a result, the four color toner images transferred onto the intermediate transfer belt 31 are transferred onto the surface of the transfer material P.

  As described above, the transfer material P onto which the four-color toner images have been transferred is guided by the conveyance guide 43 and carried into the fixing unit 40, where the upper roller pair 403, 407 and the lower roller pair 404, 408 are transferred. Be transported between. At this time, heat and nip pressure act while being sandwiched between the fixing belt 405 and the belt 406, and the toner image is fixed on the surface of the transfer material P.

  Next, the control unit controls the inner and outer paper discharge rollers 44 and 45 to convey the transfer material P on which the image is formed, to discharge it outside the apparatus and to stack it on the paper discharge tray 48. In the electrophotographic color copying machine of the present embodiment, a control unit that controls the entire apparatus is provided, but this control unit may be configured as a control unit 70 shown in FIG.

  Next, a productivity reduction sequence executed by the electrophotographic color copying machine according to the first embodiment will be described with reference to the flowchart of FIG.

  In this electrophotographic color copying machine, when the control unit receives a copying operation command or a printing operation command input by a user operating an operation unit (not shown) or the like, the productivity reduction sequence transition determination process is started.

  When the printing operation starts, the control unit determines whether the set number of prints has been completed for each print output. If the control unit determines that the print has not been completed (NO in step S41), the control unit proceeds to step S42.

  Next, the control unit determines whether or not the fixing temperature in the fixing unit 40 at that time is 170 ° C. or lower. If it is determined that the fixing temperature is 170 ° C. or lower (YES in step S42), the control proceeds to step S43. Start.

  In this productivity reduction sequence, the temperature of the fixing device is maintained at a predetermined temperature without increasing the power supplied to the fixing device. For this reason, the control unit performs control so as to reduce the amount of heat taken by the transfer material from the fixing device per unit time by opening the transfer material conveyance interval or controlling the transfer material conveyance speed to be slow. When the control unit executes the productivity reduction sequence, the printing speed (productivity) decreases. However, in this case, since the temperature of the fixing device can be prevented from falling below the temperature at which the toner can be fixed to the transfer material (for example, 170 ° C. in this embodiment), the toner can be prevented from being unfixed.

  Moreover, a control part returns to step S41, when it is judged that it is 170 degreeC or more by step S42. Then, when the control unit determines that the set number of prints has been completed in step S41 (YES in step S41), the control unit ends the productivity reduction sequence transition determination process.

  Next, a cassette heater control process executed by the electrophotographic color copying machine according to the first embodiment will be described with reference to the flowchart of FIG.

  In the electrophotographic color copying machine according to the first embodiment, the power supplied to the fixing device is 500 W when the fixing device during standby or printing is at a predetermined temperature (190 ° C.) or higher. Does not reach the upper limit. Therefore, since electric power can be supplied to the cassette heater 26 which is a transfer material heating means, this cassette heater control process is executed.

  The control unit 70 determines whether the power supplied to the fixing unit 40 is 500 W or less during standby or printing. If the control unit 70 determines that the power is 500 W or less (YES in step S51), the control unit 70 turns on the cassette heater (step S52). If the control unit 70 determines that the power is not 500 W or less (NO in step S51), it turns off the cassette heater (step S53).

  When the control unit 70 executes this cassette heater control process, the total power consumption of the electrophotographic color copying machine does not exceed 1500 W, and power can be supplied to the cassette heater even during printing. The cassette heater not only removes moisture from the moisture-absorbing transfer material, but also warms the transfer material, reducing the amount of heat taken by the transfer material from the fuser during printing operations, greatly reducing the productivity degradation sequence. , Productivity can be improved.

(Second Embodiment)
Next, an electrophotographic color copying machine according to a second embodiment of the image forming apparatus of the present invention will be described. In the second embodiment, differences from those described in the first embodiment will be mainly described.

  In the electrophotographic color copying machine shown in FIG. 1, four stages of cassettes 21a to 21d are arranged in the paper feeding unit 20, and two cassette heaters 26a and 26b serving as transfer material heating means are provided for recording paper 411, respectively. It is arranged so that it can be heated. In this electrophotographic color copying machine, the cassette heater 26a warms the recording material P for the two stages of the cassettes 21a and 21b, and the cassette heater 26b warms the recording material P for the two stages of the cassettes 21c and 21d. Yes.

  The cassette heater 26a may be arranged between the cassettes 21a and 21b or under the cassette 21b, in addition to the arrangement for heating the cassettes 21a and 21b at the upper stage of the cassette 21a. Further, each cassette heater may be arranged corresponding to each cassette.

  The effect of the cassette heater 26a warming the transfer material P is higher in the cassette 21a installed in the vicinity than in the cassette 21b. Similarly, the cassette heater 26b warms the transfer material P. Similarly, the cassette 21c installed in the vicinity is more effective than the cassette 21d.

  In this electrophotographic color copying machine, when the printing is possible after the power is turned on, the heat storage state of the fixing unit is insufficient, it is easy to enter the productivity reduction sequence described in the first embodiment. There is a tendency.

  Therefore, when printing is performed immediately after the power is turned on, it is desirable to preferentially select the cassette 21a or 21c and use a warm recording material so as to reduce the productivity reduction sequence.

  In this electrophotographic color copying machine, since the transfer material P is conveyed to the fixing device, the transfer material P is fed from the transfer material P by a cassette heater when passing through the paper feed roller pair 23 and the paper feed guide 24 constituting the conveyance path. The warmed heat is taken away. This means that the longer the distance of the transport path, the greater the amount of heat taken away. Therefore, in this electrophotographic color copying machine, the heat amount of the transfer material P carried out from the cassette 21d connected to the longest conveyance path is deprived most.

  Therefore, in this electrophotographic color copying machine, the effect of warming the transfer material P by the cassette heater is maximized by controlling to feed paper from the cassette 21a connected to the shortest conveyance path at the time of printing immediately after the power is turned on. be able to.

  Next, with reference to the flowchart of FIG. 6, a description will be given of an operation procedure for selecting a cassette so as to make the most of the effect of warming the transfer material P by the cassette heater in performing the printing operation. It is assumed that the electrophotographic color copying machine that performs the cassette selection process before the printing operation stores the recording material P of the same size.

  In this electrophotographic color copying machine, when the control unit receives a copying operation command or a printing operation command input by a user operating an operation unit (not shown), the printing process is started after execution of the control for selecting a cassette. The

  Then, the control unit determines whether or not a predetermined time (for example, 30 minutes) has elapsed after the power is turned on. If it is determined that the time has elapsed (YES in step S61), the control unit proceeds to step S63 and enters the cassette selection control 2 sequence. Follow the cassette selection.

  If the control unit determines that the predetermined time has not elapsed since the power was turned on (NO in step S61), the control unit proceeds to step S62 and follows the sequence of the cassette selection control 1 that effectively utilizes the effect of the cassette heater. Select the selected cassette.

  Next, the control unit starts a printing operation for printing using the recording material P stored in the cassette selected as described above, and ends the cassette selection process.

  Next, the process procedure of the cassette selection control 1 executed in the above-described cassette selection process will be described with reference to the flowchart shown in FIG.

  When the processing of this cassette selection control 1 is started, the control unit determines whether there is a recording material in the cassette 21a. If it is determined that there is a recording material (YES in step S71), the control unit proceeds to step S72. . Then, the control unit selects the cassette 21a (step S72) and ends the cassette selection control.

  If the control unit determines that there is no recording material in the cassette 21a (NO in step S71), the control unit proceeds to step S73 and determines whether there is a recording material in the cassette 21c. If it is determined that there is a recording material (YES in step S73), the control unit proceeds to step S74, selects the cassette 21c, and ends the cassette selection control. If the control unit determines in step S73 that there is no recording material in the cassette 21c (NO in step S73), the control unit proceeds to step S75.

  Next, the control unit determines whether there is a recording material in the cassette 21b. If it is determined that there is a recording material (YES in step S75), the control unit proceeds to step S76, selects the cassette 21b, and performs cassette selection control. finish. If it is determined that there is no recording material in the cassette 21b (NO in step S75), the process proceeds to step S77.

  Next, the control unit determines whether or not there is a recording material in the cassette 21d. If it is determined that there is a recording material (YES in step S77), the control proceeds to step S78 to select the cassette 21d and perform cassette selection control. Exit. If the control unit determines that there is no recording material in the cassette 21d (NO in step S77), the control unit proceeds to step S79.

  Next, since there is no recording material in all cassettes, the control unit displays that there is no recording material on an operation unit (not shown) (step S79). Thereafter, the control unit waits until the user replenishes the recording material P in any of the cassettes 21a to 21d (NO in step S710). Further, when it is determined that the recording material P is replenished in any of the cassettes 21a to 21d (YES in step S710), the control unit returns to step S71.

  In the cassette selection control 1 sequence described above, since the cassettes are selected in the order of short conveyance paths to the fixing device in the vicinity of the cassette heater, the shift to the productivity reduction sequence can be reduced.

  Next, the process of the cassette selection control 2 executed in the cassette selection process described with reference to FIG. 6 will be described. The cassette selection control 2 sequence in FIG. 6 performs a generally used control operation for selecting recording materials in order from the upper stage of the cassette, and does not expect the effect of the cassette heater.

  Next, a description will be given of a case where two types of recording materials P, for example, A3 and A4 are stored in four cassette stages in an electrophotographic color copying machine that performs cassette selection processing before this printing operation. In this case, the A4 recording material P is stored in the cassettes 21a and 21b, the A3 recording material P is stored in the cassettes 21c and 21d, and cassette selection control is performed.

  In the cassette selection control in the electrophotographic color copying machine in which these two types of recording materials P are stored, for example, when image formation is performed at A4, the cassette selection control process is performed according to the operation procedure shown in the flowchart of FIG. .

  In this cassette selection control process, when the control unit receives a copy operation command or a print operation command input by a user operating an operation unit or the like (not shown), the cassette selection process with control for selecting a cassette is started. The control unit determines whether there is a recording material in the cassette 21a. If it is determined that there is a recording material (YES in step S81), the control unit proceeds to step S82 to select the cassette 21a and perform cassette selection control. finish. If the control unit determines that there is no recording material in the cassette 21a (NO in step S81), the control unit proceeds to step S83.

  Next, the control unit determines whether there is a recording material in the cassette 21b. If it is determined that there is a recording material (YES in step S83), the control unit proceeds to step S84, selects the cassette 21b, and performs cassette selection control. Exit. If the control unit determines that there is no recording material in the cassette 21b (NO in step S83), the control unit proceeds to step S85.

  Next, since there is no A4 recording material in both the cassettes 21a and 21b, the control unit displays that there is no A4 recording material on an operation unit (not shown) (step S85). Thereafter, the control unit waits until the user replenishes the recording material P in either of the cassettes 21a and 21b (NO in step S86). Further, when it is determined that the recording material P is replenished in any of the cassettes 21a and 21b (YES in step S86), the control unit returns to step S81.

  As described above, even when a plurality of types of recording materials are stored in the cassette, control is performed to select the cassette in the order satisfying the condition that it is in the vicinity of the cassette heater and the condition that the conveyance path to the fixing device is short. . As a result, in the cassette selection control in the electrophotographic color copying machine in which a plurality of types of recording materials P are stored, it is possible to reduce the shift to the productivity reduction sequence and suppress the reduction in work efficiency during the printing process. .

  In this electrophotographic color copying machine, when the A3 recording material P is stored in the cassettes 21c and 21d and image formation is performed with the A3 recording material P, the cassette selection control for the A4 recording material P described above is performed. The same control is performed. In the case of such control, the same effect as in the cassette selection control for the recording material P of A4 described above can be obtained.

  In short, the electrophotographic color copying machine according to the present embodiment includes a fixing unit 40 that is a fixing device that fixes an image on a recording paper 411 that is a transfer material by pressure welding heat treatment. The fixing unit 40 includes a heating device 412 as a fixing heating unit that receives electric power from the fixing power source 415 in order to perform the pressure heating process.

  Further, this electrophotographic color copying machine preheats the recording paper 411 placed on the plurality of cassettes 21a, 21b, 21c, and 21d of the paper feeding unit 20, respectively, so that the cassette heater 26a, which is a transfer material heating means, 26b.

  The electrophotographic color copying machine also includes a control unit 70 as power control means for controlling the power supplied to the fixing unit 40, the paper feeding unit 20, and the like. This power control means has at least a function of controlling the fixing power source 415 to adjust the power supplied to the heating device 412 and a function of controlling the heating power source unit 80 to adjust the power supplied to the cassette heaters 26a and 26b. . Further, the power control means may be configured to control the power of the entire electrophotographic color copying machine.

  In the electrophotographic color copying machine configured as described above, when the image forming process is started, the power control unit controls to supply a large amount of power to the heating device 412 to heat the fixing unit 40 to the fixing temperature. Thereafter, the power control unit reduces the power supplied to the heating device 412 in order to keep the heating device 412 at a fixed fixing temperature.

  Furthermore, since the power control means has reduced the power, it can afford the maximum power amount that can be consumed by the entire electrophotographic color copying machine, so the power within the range up to the maximum power amount can be transferred to the cassette heater. Control to supply to.

  Thereby, since the recording paper 411 is preheated and then sent to the fixing unit 40, the amount of heat taken by the recording paper 411 from the fixing unit 40 can be reduced. As a result, it is possible to provide an image forming apparatus that can reduce the number of transitions to the productivity reduction sequence and suppress the reduction in work efficiency. Further, the power control means turns on the cassette heater only when the normal power supply is OFF or in the low power mode. Further, the power control means can make the heating time of the sheet as long as possible and lower the temperature when the fixing device passes through if the cassette heater is turned on even when the power supplied to the fixing unit 40 during printing is below a predetermined value. Can be reduced. The power control means may control the cassette heater to be turned on at any time within the margin when there is a margin up to the maximum power amount that can be consumed by the entire electrophotographic color copying machine. .

  Further, in this electrophotographic color copying machine, it is not necessary to cool the fixing unit 40 when the temperature of the recording paper 411 carried into the fixing unit 40 is higher. Therefore, in this electrophotographic color copying machine, in particular, image formation is performed between the time when the fixing unit 40 reaches the fixing temperature and the time when the entire fixing unit 40 is heated to a stable temperature control state at the fixing temperature. In this case, cassette selection control is performed. In this cassette selection control, the transfer material stored in the cassette that is heated most by the cassette heaters 26a and 26b is preferentially selected and fed so as to reduce the temperature when the fixing device passes. Reduce. As a result, it is possible to provide an electrophotographic color copying machine that can reduce the number of transitions to the productivity reduction sequence and can suppress a reduction in work efficiency.

  Further, in this electrophotographic color copying machine, the cassette selection control means controls to preferentially select the cassette to which the shortest conveyance path is connected and to feed the recording paper 411, so that when the fixing device is fed. Reduce temperature drop. As a result, it is possible to provide an electrophotographic color copying machine that can reduce the number of transitions to the productivity reduction sequence and can suppress a reduction in work efficiency.

40 Fixing unit 70 Control unit 26a, 26b Cassette heater

Claims (2)

A plurality of cassettes for storing transfer materials;
Image forming means for forming a toner image on a transfer material fed from any of the plurality of cassettes;
A fixing device for fixing the toner image on the transfer material by heat treatment;
Fixing heating means for heating the fixing device;
Transfer material heating means arranged to heat the transfer material housed in the plurality of cassettes ;
Corresponding to the function of controlling the power supplied to the fixing heating means and the function of controlling the power supplied to the transfer material heating means , wherein the power supplied to the fixing heating means is less than or equal to a predetermined power. Power control means for controlling the heating of the transfer material by supplying power to the transfer material heating means ;
When image formation is performed between the time when the fixing heating unit reaches the fixing temperature and the entire fixing device is heated until the temperature is stabilized at the fixing temperature, the transfer material heating unit heats most. Cassette selection control means for controlling the transfer material stored in the cassette to be preferentially selected and fed;
An image forming apparatus comprising the. Is the transfer material through different transport path of the distance from each of previous SL plurality of cassettes conveyed to the fixing device and so that arrangement,
The cassette selection control means, when the fixing heating means forms an image during a period from reaching the fixing temperature until the entire of the fixing device becomes a stable temperature control state to the heated and fixing temperature, the and wherein the benzalkonium controls so as to feed the transfer material preferentially selected the cassette and the shortest transport path in the cassette is connected that will be most heated by the transfer material heating means The image forming apparatus according to claim 1.

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