JP2017122814A - Image forming apparatus - Google Patents

Abstract

An inrush current generated in a heat source is more appropriately suppressed.
An image forming apparatus that forms an image on a recording medium includes a heat source, and a fixing unit that fixes the image formed on the recording medium using heat supplied by the heat source; A first driving unit that drives the heat source; a second driving unit that drives the heat source with different control content from the first driving unit; the first driving unit; and the second driving unit. And a switching control unit that drives the heat source.
[Selection] Figure 2

Description

  The present invention relates to an image forming apparatus.

  Some image forming apparatuses form a toner image and fix the formed toner image on a recording medium such as recording paper. This type of image forming apparatus is equipped with a fixing device for melting and fixing a toner image on a recording medium. In order to appropriately manage the temperature of the heat transfer medium such as the fixing roller employed in the fixing device, the image forming apparatus uses a heat source (heater or halogen lamp) used to supply heat to the heat transfer medium. Driving (energization) is controlled (see, for example, Patent Document 1).

  Image forming apparatuses are strongly required to increase the printing speed. For this reason, the heat capacity of the heat transfer medium employed in the fixing device tends to increase. Accordingly, the resistance value of the heat source is decreasing.

  The smaller the resistance value of the heat source, the larger the inrush current generated when supplying power. Further, the ratio of the fixing device to the power consumption of the entire image forming apparatus is high. For this reason, the inrush current generated when power is supplied to the heat source is usually very large.

  A large inrush current may cause a voltage drop in an external power supply (for example, a commercial power supply) that supplies power to the image forming apparatus. The voltage drop generated in the external power supply may cause a phenomenon called flicker (specifically, blinking of the lighting device) in other devices connected to the external power supply. For this reason, for example, in Europe, there is a legal regulation requiring that the range of voltage fluctuation in an image forming apparatus be kept below a certain level. For this reason, in the image forming apparatus, inrush current generated when power is supplied to the heat source is suppressed.

  As a method of suppressing the inrush current generated in the heat source, a period for performing phase control (hereinafter referred to as “soft start control”) is provided in the control cycle, which is a control period for driving the heat source. There is one that performs energization determined by soft start control. In the soft start control period, one energization time to the heat source is shorter than the normal energization time, and the energization time is gradually increased. When such energization control is performed, the maximum value (absolute value) of the inrush current can be suppressed, and the voltage drop generated in the external power supply can be avoided or suppressed.

  Conventional image forming apparatuses perform soft start control for each mode. However, current image forming apparatuses are becoming more multifunctional, and various peripheral devices are often prepared as optional products. Accordingly, there are many image forming apparatuses to which optional peripheral devices are connected.

  Among peripheral devices connected to the image forming apparatus, there are some peripheral devices that restrict the operation of the image forming apparatus main body. Most peripheral devices that process image-recorded recording media affect the operation of the image forming apparatus main body. This is because the processing time required for processing per recording medium is usually longer in the peripheral device than in the image forming apparatus main body. For this reason, when the peripheral device performs processing, the image forming apparatus main body is often limited to continuous image formation and operates intermittently.

  The temperature of the heat source at the start of drive control tends to depend on the operation mode of the image forming apparatus. For example, as the number of recording media to be printed per unit time (for example, the number of copies) increases, the amount of heat transfer from the heat transfer medium to the recording medium increases. Therefore, the frequency of driving the heat source is increased, and the non-drive time from the end of the heat source drive control to the start of the heat source drive control is shortened. The temperature of the heat source at the start of drive control increases as the non-drive time decreases.

  As described above, the soft start control in the conventional image forming apparatus is performed for each mode. This is because the temperature of the heat source at the start of drive control to be assumed depending on the mode, that is, the operation mode of the image forming apparatus is different. However, the operation mode of the image forming apparatus main body also changes depending on the presence of peripheral devices. Therefore, the conventional image forming apparatus has a problem that it is not always possible to appropriately suppress the inrush current generated in the heat source.

  In order to simply suppress the inrush current generated in the heat source, the soft start control period may be lengthened. However, the longer the soft start control period, the smaller the amount of heat per unit time that can be supplied to the heat transfer medium, so the printing speed decreases. In other words, productivity decreases. For this reason, it is considered that the suppression of the inrush current generated in the heat source needs to cope with the change in the operation mode according to the situation of the image forming apparatus.

  Patent Document 1 includes a DC power supply unit that is a main power source that supplies power to a first load that is continuously driven and a battery that intermittently supplies power to a second load that is intermittently driven. An image forming apparatus is described. In this conventional image forming apparatus, the peak current due to the inrush current generated by the intermittently driven load is smoothed by the capacitor, thereby suppressing the peak current itself that enters the main power source.

  The present invention has been made to solve such a problem, and an object thereof is to more appropriately suppress an inrush current generated in a heat source.

  In order to solve the above-described problem, an aspect of the present invention is an image forming apparatus that forms an image on a recording medium, the image forming apparatus having a heat source, and using the heat supplied by the heat source. A fixing unit that fixes the image formed thereon, a first driving unit that drives the heat source, a second driving unit that drives the heat source with different control content from the first driving unit, and And a switching control unit that drives one of the first driving unit and the second driving unit to drive the heat source.

  According to the present invention, the inrush current generated in the heat source can be more appropriately suppressed.

1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment. It is a figure explaining the functional structure of the control part mounted in the image forming apparatus by this embodiment. It is a figure explaining the example of the content of soft start control. It is a figure explaining the example of the contents of soft stop control. It is a figure explaining the switching control performed when operating a peripheral machine. It is a flowchart showing a switching control process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating the configuration of the image forming apparatus according to the present embodiment, and FIG. 2 is a diagram illustrating the functional configuration of a control unit mounted on the image forming apparatus.

  The image forming apparatus 1 according to the present embodiment is, for example, a multifunction machine, and can perform copying, printing, facsimile transmission / reception, document storage, and the like. As shown in FIG. 1, the image forming apparatus 1 includes a main power switch (SW) 11, a DC (Direct Current) power generation circuit 12, an operation unit 13, a dedicated device group 14, a peripheral device 15, a fixing device 16, a temperature. A sensor 17, an AC (Alternating Current) heater drive circuit 18, a power storage device 19, a fixing heater power supply switching circuit 20, and a control unit 21 are provided. This configuration is an example, and the configuration of the image forming apparatus is not limited to this.

  The main power switch 11 is a device that opens and closes a power supply path from an external power source (for example, a commercial power source) 2. Power (AC power) from the external power supply 2 is supplied to the DC power generation circuit 12, the AC heater drive circuit 18, and the power storage device 19 via the main power switch 11.

  The DC power supply generation circuit 12 generates a power supply voltage Vcc having a predetermined voltage using AC power supplied via the main power switch 11. The DC voltage Vcc is applied to the operation unit 13, the control unit 21, the dedicated device group 14, and the peripheral device 15.

  The operation unit 13 is a device that can be used by the user for various instructions or data input. The operation unit 13 includes a touch panel using, for example, an LCD (Liquid Crystal Display), various keys, and the like.

  The dedicated device group 14 performs processing necessary for image formation on a recording medium such as recording paper. The dedicated device group 14 includes, for example, an ADF (Automatic Document Feeder), a scanner unit, an exposure apparatus, a modem, and a transport unit.

  The peripheral unit 15 is an apparatus that is actually connected to the image forming apparatus 1 among optional products. As an example of the peripheral machine 15 assumed here, a Z-fold and punch hole can be formed on a recording medium on which an image is formed, a recording medium can be cut, and a plurality of recording media can be bound together. And the like.

  In FIG. 1, the peripheral unit 15 is applied with the power supply voltage Vcc from the image forming apparatus 1. However, the peripheral unit 15 may be a type that is directly connected to the external power source 2 or may be a type that is indirectly connected, for example, a type that is mounted or connected to another device. Further, the number of peripheral devices 15 that can be added to the image forming apparatus 1 is not limited to one.

  The fixing device 16 is a device that melts and fixes the toner image on the recording medium by applying pressure and heat to the recording medium to which the toner image is transferred. One or more fixing heaters 31 are provided as a heat source for supplying heat to a heat transfer medium such as a fixing roller. The type of the fixing heater 31 is not limited, but here, the fixing heater 31 is assumed to generate heat by lighting a halogen lamp or the like.

  The temperature sensor 17 is a sensor arranged to detect the temperature of the heat transfer medium, for example, a thermistor. The detection signal S3 output from the temperature sensor 17 is input to the control unit 21. The type of the temperature sensor 17 is not limited.

  The AC heater drive circuit 18 is a drive circuit for driving the fixing heater 31 in accordance with the control signal S1 output from the control unit 21, that is, for energization. The AC heater drive circuit 18 detects a zero cross point of the AC voltage applied via the main power switch 11 and activates the zero cross signal S2. The zero cross signal S2 is used by the control unit 21 to generate the control signal S1. As described above, since the control signal S1 output from the control unit 21 is necessary for driving the fixing heater 31 by the AC heater driving circuit 18, the first driving unit in the present embodiment is the AC heater driving circuit 18, and This is realized by the control unit 21.

  In the present embodiment, the fixing heater 31 is driven using soft start control. FIG. 3 is a diagram for explaining a content example of the soft start control. Here, the soft start control will be described in detail with reference to FIG. In FIG. 3, the waveform represents an AC voltage. The “soft start period” represents a period during which soft start control is performed.

  In the soft start control, the minimum unit for controlling energization to the heat source is a half cycle of the AC voltage. In FIG. 3, the period during which the heat source is energized within the half cycle, which is the minimum unit, is indicated by filling. “13%”, “14%”, “15%” and the like in parentheses as the heater lighting duty indicate the ratio of the period during which the heat source is actually energized within a half cycle.

  In FIG. 3, “lighting” is described including the heater lighting duty because it is assumed that the heat source to be driven is a type that generates heat by lighting. In FIG. 3, the fixing heater 31 itself is not assumed. However, in order to avoid confusion, hereinafter, the fixing heater 31 is assumed as a heat source used in the description of FIG. In accordance with this, it is assumed that the fixing heater 31 is a type that generates heat when it is turned on, and “heater lighting duty” is a term that indicates a ratio of actual energization in the minimum unit for controlling energization to the fixing heater 31. Use.

  In the soft start control, as shown in FIG. 3, the heater lighting duty is changed to gradually increase. Therefore, by using the soft start control, it is possible to raise the temperature of the fixing heater 31 while suppressing the inrush current generated in the fixing heater 31. The first heater lighting duty in the soft start period, the heater lighting duty increment, the last heater lighting duty, and the like are treated as parameters.

  After the soft start control is completed, the fixing heater 31 is turned on at a predetermined heater lighting duty. In FIG. 3, the period during which the fixing heater 31 is turned on is referred to as a “full lighting period”. In the example shown in FIG. 3, zero cross control with a heater lighting duty of 100% is performed in the full lighting period.

  The control signal S1 output from the control unit 21 is active during a period in which the AC heater driving circuit 18 should turn on the fixing heater 31. The zero cross signal S2 is used to determine the timing for activating the control signal S1. Therefore, by causing the AC heater driving circuit 18 to drive the fixing heater 31 in accordance with the control signal S1, the control unit 21 can turn on the fixing heater 31 in either the soft start control or the zero cross control.

  FIG. 4 is a diagram for explaining a content example of the soft stop control. This soft stop control is a control that is performed when the lighting control of the fixing heater 31 is ended, contrary to the soft start control. In FIG. 4, as in FIG. 3, the waveform represents the AC voltage. The “soft stop period” represents a period during which this soft stop control is performed.

  In this soft stop control, the heater lighting duty is changed to be gradually reduced. Thereby, an inrush current generated when the lighting control of the fixing heater 31 is finished is suppressed. Therefore, soft stop control may be used in combination with soft start control. Also in the soft stop control, the first heater lighting duty in the soft stop period, the increment of the heater lighting duty, the last heater lighting duty, and the like are treated as parameters.

  The power storage device 19 is a device mounted to drive the fixing heater 31 and corresponds to the second drive unit in the present embodiment. As shown in FIG. 1, the power storage device 19 includes a charging circuit 41, a rechargeable battery 42, and a heater driving device 43.

  The charging circuit 41 converts AC power supplied via the main power switch 11 into DC power and charges the rechargeable battery 42. The heater driving device 43 is a driving device for driving the fixing heater 31 using the rechargeable battery 42 as a power source, and drives the fixing heater 31 by soft start control as shown in FIG. The heater driving device 43 corresponds to the driving circuit in this embodiment. The heater driving device 43 may perform a soft stop control as shown in FIG.

  The fixing heater power supply switching circuit 20 enables the fixing heater 31 to be driven by one of the AC heater driving circuit 18 and the power storage device 19. Accordingly, the fixing heater power supply switching circuit 20 functions as a switch for switching the connection destination of the fixing heater 31 from the AC heater driving circuit 18 and the power storage device 19. The connection destination is switched according to a control signal S4 output from the control unit 21. The fixing heater power supply switching circuit 20 corresponds to a switching unit in the present embodiment.

  The control unit 21 is a data processing device (computer) for controlling the entire image forming apparatus 1. As shown in FIG. 1, the control unit 21 includes a CPU (Central Processing Unit) 51, a RAM (Random Access Memory) 52, a ROM (Read Only Memory) 53, a hard disk device (HDD: Hard Disk Drive) 54, an I / O An F (InterFace) card 55 and a bus 56 are provided.

  The ROM 53 is a read-only nonvolatile storage medium, and stores firmware and various data. The RAM 52 is a volatile storage medium capable of reading and writing information at high speed, and is used as a work area when the CPU 51 processes information.

  The hard disk device 54 is a storage device capable of reading and writing information. The installed hard disk 541 includes various programs such as an OS (Operating System), various control programs, and various application programs in addition to various data. Is stored. The hard disk device 54 is also used for temporarily storing image data such as a document.

  Various data stored in the hard disk 541 includes a drive control information group for controlling the AC heater drive circuit 18. Most of the drive control information constituting the drive control information group is for driving the fixing heater 31 by soft start control. The various control programs include a switching control program 542 for controlling the fixing heater power supply switching circuit 20 to switch the connection destination of the fixing heater 31.

  The I / F card 55 is a communication control device for communicating with each dedicated device constituting the dedicated device group 14, the peripheral device 15, and a network. Here, only one I / F card 55 is shown, but a plurality of I / F cards 55 may be mounted. An I / F different from the I / F via the I / F card 55 is used for the outputs of the control signals S1 and S4 and the inputs of the zero cross signal S2 and the detection signal S3.

  When the power is turned on, the CPU 51 reads the firmware stored in the ROM 53 into the RAM 52 and executes it. Thereafter, the OS and necessary programs are read from the hard disk device 54 onto the RAM 52 and executed. After starting up in this way, a process for responding to a user instruction via the operation unit 13 or an instruction via the network is performed. By executing the processing, the CPU 51 controls the entire image forming apparatus 1 to realize the functional configuration shown in FIG.

  As shown in FIG. 2, the control unit 21 includes a dedicated device control unit 201, a peripheral device control unit 202, a transport control unit 203, an operation input unit 204, a fixing control unit 205, a switching control unit 206, and a main configuration as functional configurations. A control unit 207 is provided.

  The dedicated device control unit 201 recognizes a dedicated device mounted on or connected to the image forming apparatus 1, and individually controls each dedicated device according to an instruction from the main control unit 207. The peripheral device control unit 202 recognizes the peripheral device 15 connected to the image forming apparatus 1 and controls it according to an instruction from the main control unit 207. The recognition of the dedicated device is performed, for example, by identification information output from the dedicated device when the power is turned on (started up). The same applies to the recognition method of the peripheral device 15. Identification information output from each dedicated device and the peripheral device 15 is stored in the hard disk device 54 by the CPU 51 as, for example, configuration information representing a system configuration (environment).

  The transport control unit 203 controls the transport unit and performs a process for dealing with an error or the like notified from the transport unit. The operation input unit 204 analyzes the user's operation content notified from the operation unit 13, interprets the user's instruction or input data, and passes the interpretation result to the main control unit 207. Further, the operation unit 13 is controlled in accordance with an instruction from the main control unit 207. As a result, the display content of the display device of the touch panel is updated as needed, and the operation mode of the main body of the image forming apparatus 1 or the operation mode of the peripheral device 15 is changed as necessary.

  The fixing control unit 205 controls the fixing device 16. Mainly, control for driving the fixing heater 31 through the AC heater driving circuit 18 is performed. The control of the AC heater driving circuit 18 is performed according to an instruction from the main control unit 207 when the temperature represented by the detection signal S3 is equal to or lower than a predetermined temperature.

  The switching control unit 206 performs switching control for the fixing heater power supply switching circuit 20. The switching control unit 206 corresponds to the switching control unit in the present embodiment.

  The main control unit 207 processes information passed from the operation input unit 204 and controls the entire image forming apparatus 1. When performing printing by copying or the like, that is, when forming an image on a recording medium, the main control unit 207 controls the units 201 to 206 to manage the progress of the printing process and to operate the dedicated device and the peripheral device 15. To work properly. For this purpose, the main control unit 207 obtains necessary information from the dedicated device control unit 201, the peripheral device control unit 202, the transport control unit 203, the operation input unit 204, and the like, processes the acquired information, and the processing result. Various instructions are given.

  The dedicated device control unit 201, peripheral device control unit 202, transport control unit 203, operation input unit 204, and main control unit 207 all have a CPU 51, a RAM 52, a ROM 53, a hard disk device 54, an I / F card 55, and a bus. 56. This is because the CPU 51 executes the program stored in the ROM 53 or the hard disk device 54 and performs communication using the I / F card 55 as necessary.

  On the other hand, the fixing control unit 205 and the switching control unit 206 are realized by the CPU 51, the RAM 52, the ROM 53, the hard disk device 54, and the bus 56. The reason why the I / F card 55 is not included is that drive control of the AC heater drive circuit 18 and switching control of the power storage device 19 are performed via an I / F that does not go through the I / F card 55.

  Among peripheral devices 15 that can be connected to the image forming apparatus 1, there are those that restrict the operation of the image forming apparatus 1 main body. Peripheral machine 15 as described above, that is, one that can perform Z-folding and punch punching on an image-formed recording medium, one that can cut a recording medium, and one that can bind a plurality of recording media Etc., the image forming apparatus 1 main body is restricted in operation.

  When the peripheral device 15 is connected to the main body of the image forming apparatus 1, the user can operate the operation unit 13 to cause the peripheral device 15 to perform processing. Depending on the peripheral unit 15, an operation mode can be set. The peripheral unit 15 assumed here is assumed to restrict the operation of the main body of the image forming apparatus 1 unless otherwise specified.

  When the peripheral unit 15 that affects the operation of the main body of the image forming apparatus 1 operates, the main body of the image forming apparatus 1 operates intermittently. For example, the main body of the image forming apparatus 1 is in a standby state after supplying the processable number of recording media to the peripheral device 15 and until the peripheral device 15 becomes ready to accept the recording medium again. In the standby state, since the amount of heat transfer from the heat transfer medium to the recording medium does not occur, the non-lighting time during which the fixing heater 31 is not turned on becomes longer, and the temperature of the fixing heater 31 at the start of lighting control becomes lower.

  As the temperature of the fixing heater 31 decreases, the generated inrush current increases. As a result, problems such as flicker easily occur. As the heater lighting duty is decreased, the inrush current can be suppressed. However, as the heater lighting duty is reduced, the amount of heat that can be supplied from the fixing heater 31 per unit time is reduced, leading to a decrease in productivity. There is also a problem that a harmonic component is generated in the power supply current supplied by the external power supply 2. This harmonic component can cause melting of the power fuse or malfunction of the breaker. For this reason, the strength of harmonic components is limited by laws and regulations.

  These mean that even if the soft start control of the fixing heater 31 is performed according to the mode, the inrush current cannot be appropriately suppressed. For this reason, the power storage device 19 and the fixing heater power supply switching circuit 20 respond to the influence of the main body of the image forming apparatus 1 accompanying the operation of the peripheral unit 15, that is, the change in the operation mode of the main body of the image forming apparatus 1. Are prepared.

  FIG. 5 is a diagram for explaining the switching control performed when the peripheral unit 15 is operated. Here, the switching control realized by the switching control unit 206 will be specifically described with reference to FIG.

  In order to explain the switching control, in FIG. 5, “main body operation”, “peripheral device operation”, “fixing heater power”, “electric storage device power supply current transition”, “fixing heater power supply switching circuit”, “power storage device operation” are represented. The operation content is shown. Specifically, these operations represent the following contents.

  First, “main body operation” represents an operation for print processing of the main body of the image forming apparatus 1. Two terms, “operation” and “standby”, are expressed as terms representing the operation content. The operation here represents a state in which the operation for the printing process is actually performed, and the standby represents a standby state in which the processing by the peripheral device 15 is awaited. In FIG. 5, the period during which the operation for the printing process is actually performed is emphasized by hatching.

  The “peripheral device operation” represents an operation for recording medium processing by the peripheral device 15. Two terms, “operation” and “standby”, are expressed as terms representing the operation content. The operation here represents a state in which an operation for processing the recording medium ejected from the main body of the image forming apparatus 1 is actually performed. In the standby state, a necessary number of recording media are ejected from the main body of the image forming apparatus 1. It represents a waiting state waiting for being performed. In FIG. 5, as in the image forming apparatus 1 main body, the period during which the operation for processing the recording medium is actually performed is emphasized by hatching.

  As shown in FIG. 5, the image forming apparatus 1 main body and the peripheral unit 15 are in a standby state when the image forming apparatus 1 main body is operating, and the image forming apparatus 1 main body is in a standby state while the peripheral unit 15 is operating. It becomes. As described above, when the peripheral device 15 performs processing, both the image forming apparatus 1 main body and the peripheral device 15 operate intermittently.

  “Fixing heater power” represents the amount of power supplied to the fixing heater 31. Two terms “high duty” and “low duty” are shown as terms representing the amount of electric power. The high duty here means that the amount of power supplied to the fixing heater 31 per unit time is large. The amount of electric power enables continuous printing. On the other hand, the low duty represents a clearly lower level of power supply compared to the high duty.

  “Power storage device power supply current transition” represents a transition of the amount of current supplied from the power storage device 19 to the fixing heater 31. Two terms of “high” and “low” are shown as terms representing the amount of current. High represents a state in which current is supplied to the fixing heater 31, and low represents a state in which no current is supplied to the fixing heater 31.

  The “fixing heater power source switching circuit” represents a switching operation of the connection destination of the fixing heater 31. Two terms of “ON” and “OFF” are described as terms representing the switching operation. ON indicates a state in which a switching instruction is input by the control signal S4 or a switching operation is performed, and OFF indicates a state in which a switching instruction is not input by the control signal S4 or a switching operation is not performed. Here, it is assumed that they represent a switching instruction input by the control signal S4. The connection destination of the fixing heater 31 is switched by a switching instruction by the control signal S4.

  “Power storage device operation” represents a charge / discharge operation by the power storage device 19. As a result, two terms of “discharge” and “charge” are described as terms representing the charge / discharge operation. Here, discharging means a state where the fixing heater 31 is energized, and charging means a state where the fixing heater 31 is not energized.

  The main control unit 207 performs print processing for forming an image on a recording medium and recording with image formation through various instructions to the dedicated device control unit 201, the peripheral device control unit 202, the conveyance control unit 203, and the fixing control unit 205. Realize processing to media. Further, the progress of the printing process is confirmed through notifications from the dedicated device control unit 201 and the conveyance control unit 203, and the progress of processing by the peripheral unit 15 is confirmed through notifications from the peripheral unit control unit 202.

  Accordingly, when the main body of the image forming apparatus 1 is in operation, the main control unit 207 specifies the timing for interrupting the operation of the main body of the image forming apparatus 1 and switches the fixing heater power supply switching circuit 20 in accordance with the specified timing. Control is performed and the peripheral unit 15 is started to operate. Further, when the peripheral unit 15 is operating, the timing at which the operation of the peripheral unit 15 ends is specified, and switching control for the fixing heater power supply switching circuit 20 is performed in accordance with the specified timing, so that the operation of the main body of the image forming apparatus 1 is performed. To resume. As a result, as shown in FIG. 5, when the main body of the image forming apparatus 1 is in the standby state, the power storage device 19 is lit with the fixing heater 31, and when the main body of the image forming apparatus 1 is in the operating state, the fixing heater 31 is supplied to the AC heater driving circuit 18. Lights up.

  Since the recording medium is not conveyed to the fixing device 16 when the main body of the image forming apparatus 1 is in the standby state, the amount of heat to be supplied by the fixing heater 31 is small. Therefore, when the fixing heater 31 is turned on according to the temperature detected by the temperature sensor 17, the drive control interval of the fixing heater 31 becomes longer, and the temperature of the fixing heater 31 at the start of the drive control becomes lower than the assumed temperature.

  The inrush current increases as the temperature of the fixing heater 31 decreases. In order to suppress the inrush current, the smaller the heater lighting duty, the smaller the amount of heat per unit time that can be supplied to the heat transfer medium, and the higher the harmonic component. Therefore, in the present embodiment, the power storage device 19 and the fixing heater power supply switching circuit 20 are prepared so that the fixing heater 31 is lit on the power storage device 19 while the main body of the image forming apparatus 1 is in the standby state.

  The lighting of the fixing heater 31 by the power storage device 19 is performed in order to maintain the temperature of the fixing heater 31 at a level that can sufficiently suppress the inrush current. Thus, when the operation of the image forming apparatus 1 is resumed, the inrush current is greatly reduced even if soft start control for a relatively short time, in other words, soft start control having a relatively large initial value of the heater lighting duty is performed. It can be suppressed to a low level. Therefore, generation of harmonic components in the power supply current supplied by the external power supply 2 can be avoided or suppressed.

  When the temperature detected by the temperature sensor 17 is equal to or lower than the predetermined temperature, the main control unit 207 instructs the fixing control unit 205 to turn on the fixing heater 31 using the AC heater driving circuit 18. However, when the main body of the image forming apparatus 1 is in a standby state, the fixing heater 31 using the AC heater driving circuit 18 cannot be turned on.

  For this reason, in this embodiment, the lighting of the fixing heater 31 by the power storage device 19 is performed so that the temperature detected by the temperature sensor 17 does not fall below a predetermined temperature and does not reach the upper limit temperature.

  When the fixing heater 31 is turned on as described above, the temperature of the heat transfer medium when the operation of the main body of the image forming apparatus 1 is resumed is maintained at a higher state. Unlike the prior art, the temperature of the heat transfer medium can be maintained at a temperature exceeding a predetermined temperature. For this reason, when the operation of the main body of the image forming apparatus 1 is resumed, image formation on the recording medium can be started more quickly. Therefore, there is an advantage in terms of productivity.

  As described above, the drive control for turning on the fixing heater 31 is possible without checking the temperature of the heat transfer medium using the temperature sensor 17 or the like. This is because, since the temperature difference between the predetermined temperature and the upper limit temperature is usually larger than the range of the ambient temperature of the heat transfer medium, the accuracy required for control is reduced. Accordingly, in the present embodiment, an autonomous type capable of performing drive control with predetermined contents is adopted as the heater driving device 43 mounted on the power storage device 19.

  When the autonomous heater driving device 43 is employed, the main control unit 207 does not need to perform control for turning on the fixing heater 31 while the main body of the image forming apparatus 1 is in the standby state. From this, it is possible to prevent the control from becoming complicated as the connection destination of the fixing heater 31 is switched.

  The heater driving device 43 operates using the rechargeable battery 42 as a power source. Therefore, it is possible to avoid the inrush current generated by causing the heater driving device 43 to light the fixing heater 31 to affect the external power source 2.

  The switching control unit 206 switches the connection destination of the fixing heater 31 as described above. The switching control unit 206 is realized by the CPU 51 executing the switching control program 542 stored in the hard disk device 54. Next, the switching control process realized by the CPU 51 executing the switching control program 542 will be described in detail with reference to the flowchart shown in FIG.

  This switching control program 542 is a subprogram that is called by the main program, for example, at the start of printing, at the timing of shifting to the standby state of the main body of the image forming apparatus 1, at the end of processing of the peripheral device 15, and at the end of printing. From this main program to the switching control program 542, for example, printing status information indicating whether or not printing is in progress, peripheral device information indicating whether or not the peripheral device 15 is connected, and whether or not the main body of the image forming apparatus 1 shifts to a standby state. State status information indicating The main program is a program for realizing the main control unit 207, for example.

  When control is passed to the switching control program 542, the CPU 51 first determines whether printing is in progress (S501). If the printing status information indicates that printing is in progress, the determination in S501 is YES and the process proceeds to S502.

  In S502, the CPU 51 determines whether or not the peripheral device 15 is connected. If the peripheral device information indicates the presence of the peripheral device 15, the determination in S502 is YES and the process proceeds to S503. If the peripheral device information does not indicate the presence of the peripheral device 15, the determination in S502 is NO, and the switching control process ends here.

  In S503, the CPU 51 determines whether or not the peripheral device 15 operates. If the status information represents a shift to the standby state of the main body of the image forming apparatus 1, in other words, if the status status information indicates that the peripheral unit 15 is operating, the determination in S503 is YES and the processing returns to S504. Transition.

  In S <b> 504, the CPU 51 outputs a control signal S <b> 4 to the fixing heater power supply switching circuit 20 to connect the power storage device 19 to the fixing heater 31. Thereafter, the switching control process ends. By the switching, the state shifts to a state in which the fixing heater 31 can be turned on by the power storage device 19.

  On the other hand, if the status information does not represent the transition of the image forming apparatus 1 main body to the standby state, the determination in S503 is NO and the process proceeds to S505. In S <b> 505, the CPU 51 outputs a control signal S <b> 4 to the fixing heater power supply switching circuit 20 to connect the AC heater driving circuit 18 to the fixing heater 31. Thereafter, the switching control process ends. By the switching, the AC heater driving circuit 18 shifts to a state where the fixing heater 31 can be turned on.

  If the print status information does not indicate that printing is in progress, that is, if the print status information indicates that printing has ended, the determination in S501 is NO and the process proceeds to S505. Accordingly, the fixing heater 31 is turned on by the AC heater driving circuit 18 after the printing is completed until the next printing is started.

  In this embodiment, the connection destination of the fixing heater 31 is switched by the fixing heater power source switching circuit 20. A configuration not including the fixing heater power supply switching circuit 20 may be employed. For example, two types of fixing heaters 31, one that drives the power storage device 19 and one that drives the AC heater drive circuit 18, are prepared, and the timing for driving the power storage device 19 (and the AC heater drive circuit 18) is controlled. Anyway.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 External power supply 13 Operation part 14 Dedicated device group 15 Peripheral machine 16 Fixing apparatus 18 AC heater drive circuit 19 Power storage apparatus 20 Fixing heater power supply switching circuit 21 Control part 31 Fixing heater 41 Charging circuit 42 Rechargeable battery 43 Heater drive apparatus 51 CPU
52 RAM
53 ROM
54 Hard Disk Device 55 I / F Card 56 Bus 201 Dedicated Device Control Unit 202 Peripheral Device Control Unit 203 Transport Control Unit 204 Operation Input Unit 205 Fixing Control Unit 206 Switching Control Unit 207 Main Control Unit 541 Hard Disk 542 Switching Control Program

JP 2007-166765 A

Claims (6)

An image forming apparatus for forming an image on a recording medium,
A fixing unit having a heat source and fixing the image formed on the recording medium using heat supplied by the heat source;
A first drive unit for driving the heat source;
A second drive unit that drives the heat source with different control content from the first drive unit;
A switching control unit for driving one of the first driving unit and the second driving unit to drive the heat source;
An image forming apparatus comprising: A peripheral unit that controls the peripheral unit when a peripheral unit that performs processing on the recording medium on which the image is formed is connected to the image forming apparatus;
The switching control unit drives one of the first driving unit and the second driving unit to drive the heat source based on the control content of the peripheral unit by the peripheral unit control unit. The image forming apparatus according to claim 1.   The switching control unit is configured to restrict the operation of the main body of the image forming apparatus generated by a combination of the peripheral unit and an operation mode of the peripheral unit when the peripheral unit control unit operates the peripheral unit under control. The image forming apparatus according to claim 2, wherein the heat source is driven by the second driving unit based on the image forming apparatus.   The switching control unit causes the second driving unit to drive the heat source when the operation of the main body of the image forming apparatus is temporarily interrupted due to the restriction. Item 4. The image forming apparatus according to Item 3.   The second drive unit includes a rechargeable battery that is charged by power supplied from an external power source, and a drive circuit that can drive the heat source using the power supplied from the rechargeable battery. The image forming apparatus according to any one of claims 1 to 4.   The switching control unit controls a switching unit that connects one of the driving circuit and the first driving unit to the heat source, and includes the first driving unit and the second driving unit. The image forming apparatus according to claim 1, wherein the heat source is driven by one of the two.