JP6136611B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to power supply control to a halogen heater that heats a fixing heating member.

  As an image forming apparatus, when fixing a toner image onto a recording medium, an apparatus that passes the recording medium through a nip formed by, for example, a heating roller (an example of a fixing heating member) and a pressure roller is known. The heating roller has, for example, a halogen heater inside the roller.

  The electric power is supplied to the halogen heater so as to maintain the surface temperature of the heating roller close to the target temperature. Specifically, while the power supply to the halogen heater is stopped, the power supply to the halogen heater is started when the surface temperature of the heating roller falls below a predetermined lower limit value, and the power supply to the halogen heater is in progress. In addition, when the surface temperature of the heating roller rises and exceeds a predetermined upper limit value that is not lower than the lower limit value, the power supply to the halogen heater is stopped.

  In such power supply control to the halogen heater, the surface temperature of the heating roller may not be less than a predetermined lower limit value. In such a case, the state in which no electric power is supplied to the halogen heater continues for a relatively long time. In recent years, in particular, product development has been made with the aim of shortening the warm-up time. For this reason, the heater capacity of the halogen heater is increased, the heating roller is downsized, and the fixing is performed at a lower temperature than in the past. Therefore, the time during which the power supply to the halogen heater is stopped tends to be prolonged.

  However, if the power supply to the halogen heater is stopped for a long time, the temperature of the filament of the halogen heater becomes too low. This decrease in the temperature of the filament causes a decrease in the electrical resistance of the filament. Therefore, when power is supplied to the halogen heater in such a state, an inrush current far exceeding the rated current flows instantaneously. As a result, fluorescent lamps in the room where the image forming apparatus is installed flickers (so-called “flicker” phenomenon), which affects the operation of peripheral devices of the image forming apparatus.

  Incidentally, Patent Document 1 below describes an example of energization control for a halogen heater included in a fixing device of an image forming apparatus. In the image forming apparatus described in this document, the duty is appropriately adjusted by controlling the wave number of the AC voltage in half-wave units. And by such energization control, it is trying to keep the temperature of the halogen heater near the target temperature. Furthermore, in the image forming apparatus disclosed in this document, the harmonic current increases as the number of times the energization is switched on and off, and when the temperature of the halogen heater is lower than a predetermined value, the duty is fixed to 100%. It is said. In this way, an attempt is made to suppress the increase in harmonic current.

JP 2012-189622 A

  However, the technique described in the above document simply energizes the halogen heater with the duty fixed at 100% when the temperature of the halogen heater becomes a predetermined value or less. Therefore, in such control, it is not possible to suppress an increase in inrush current due to a prolonged time until the surface temperature of the heating roller becomes equal to or lower than a predetermined lower limit value.

  The present invention has been made in view of the above circumstances. That is, an object of the present invention is to provide an image forming apparatus that hardly affects the operation of peripheral devices by suppressing the inrush current of the halogen heater from becoming too large.

The image forming apparatus of the present invention, which has been made for the purpose of solving this problem, has an image forming unit for forming a toner image on a recording medium (hereinafter referred to as “image formation”) and a halogen heater. A fixing heating member that contacts the recording medium on which the toner image is formed and fixes the toner image on the recording medium, and a first temperature measurement unit that outputs a temperature measurement value indicating the temperature of the fixing heating member. In the image forming apparatus including the heater control unit that controls power supply to the halogen heater, the heater control unit reduces the temperature measurement value of the first temperature measurement unit while the power supply to the halogen heater is stopped. When the value falls below a predetermined lower limit, power supply to the halogen heater is started, and the temperature measurement value of the first temperature measurement unit rises during power supply to the halogen heater. First control for stopping power supply to the halogen heater when a predetermined upper limit value that is not lower than the lower limit value is exceeded, and a first period of a predetermined length after the power supply to the halogen heater is stopped Then, even if no temperature measurements of the first temperature measuring unit is equal to or smaller than the lower limit value, Ru der to perform a second control for supplying power to the halogen heater for a second period length a predetermined .

  According to the present invention, the heater control unit performs the second control described above. Therefore, power is not supplied to the halogen heater for a long time. Therefore, the temperature of the filament of the halogen heater does not decrease too much and the electrical resistance of the filament does not become extremely small. Therefore, it is possible to prevent the operation of peripheral devices of the image forming apparatus from being influenced by an excessive inrush current.

  Here, in the image forming apparatus of the present invention, it is desirable that the heater control unit does not perform the second control when image formation is being performed.

  When image formation is being performed, the heat of the fixing heating member is taken away by the recording medium by the fixing operation after image formation. For this reason, the temperature of the fixing heating member quickly decreases as compared to when no image formation is performed. Therefore, the power supply interval to the halogen heater in the first control when image formation is being performed is relatively short. Therefore, even if the second control is not performed, there is a low possibility that the inrush current becomes excessive. Therefore, in the present invention, the heater control unit does not perform the second control when image formation is being performed. With this configuration, it is possible to prevent the inrush current from becoming too large while reducing the processing load on the control unit during image formation.

Further, in the image forming apparatus according to one aspect of the present invention, compared to the first temperature measurement unit, the temperature measurement value at a position that is less influenced by the temperature of the fixing heating member and more influenced by the environmental temperature is obtained. a second temperature measuring unit for outputting, the heater control unit, Ru der those temperature measurements of the second temperature measuring unit is longer higher first period. Here, “less affected by the temperature of the fixing heating member” includes those that are not affected by the temperature of the fixing heating member at all. In other words, the second temperature measurement unit may not be affected at all by the temperature of the fixing heating member.

  The higher the ambient temperature, the less likely the temperature of the halogen heater filament will decrease. Therefore, in the present invention, the higher the environmental temperature, the longer the power supply interval to the halogen heater in the second control. If comprised in this way, the frequency | count of supplying electric power to a halogen heater as 2nd control can be decreased.

In the image forming apparatus according to another aspect of the present invention, the heater control unit supplies power to the halogen heater by receiving power from an external power source, and the higher the voltage of the external power source, Ru der things to lengthen the first period.

  The higher the voltage of the external power supply, the higher the voltage applied to the halogen heater. For this reason, the current required for the halogen heater to exhibit a desired heater capacity is small. Therefore, the possibility that an excessive inrush current flows is reduced. Therefore, in the present invention, the higher the voltage of the external power supply, the longer the power supply interval to the halogen heater in the second control. If comprised in this way, the frequency | count of supplying electric power to a halogen heater as 2nd control can be decreased.

In yet another one embodiment the image forming apparatus of the present invention is also a heater control unit, Ru der performs only second control when it is within the range where the voltage of the external power supply is predetermined.

Some countries where image forming devices are destined are required by law to make products that do not affect the operation of peripheral devices. Therefore, if configured as in the present invention, considering the voltage of the external power supply when the image forming apparatus is used in such a country, it is possible to easily set the voltage range for performing the second control. It can be a product that conforms to the legal system. This aspect further includes a second temperature measurement unit that outputs a temperature measurement value at a position that is less affected by the temperature of the fixing heating member and more affected by the environmental temperature than the first temperature measurement unit. The heater control unit preferably further performs the second control only when the temperature measurement value of the second temperature measurement unit is within the predetermined range.

In the image forming apparatus of still another aspect of the present invention, the fixing heating member includes a plurality of halogen heaters having different heater capacities, and the heater control unit has a heater capacity of the plurality of halogen heaters. Ru der performs second control for one or two halogen heaters including those and heater capacity free of smallest largest.

  The larger the heater capacity, the larger inrush current may flow. Therefore, if configured as in the present invention, it is possible to suppress the inrush current of the halogen heater that most easily affects the operation of the peripheral device.

  According to the present invention, there is provided an image forming apparatus which is less likely to affect the operation of peripheral devices by suppressing the inrush current of the halogen heater from becoming too large.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. 2 is a schematic perspective view of a fixing device provided in the image forming apparatus. FIG. FIG. 2 is a block diagram showing an electrical system related to the fixing device. It is a timing chart when only the first control is executed among the voltage application controls to the halogen heater provided in the fixing device. It is a graph which shows the relationship between the time which has turned off the halogen heater, and inrush current. It is a timing chart at the time of performing 2nd control in addition to 1st control as voltage application control to a halogen heater. 6 is a timing chart showing the transition of the surface temperature of the heating roller and the on / off of the halogen heater when the image forming apparatus is actually printing. It is a perspective view showing a fixing device according to a modification. FIG. 10 is a perspective view showing a fixing device according to another modification. FIG. 11 is a perspective view showing a fixing device according to still another modification.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for embodying the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a configuration example of an image forming apparatus according to the present invention. An image forming apparatus 1 shown in FIG. 1 is an electrophotographic tandem digital color printer (hereinafter simply referred to as “printer”). Of course, in addition to the printer, the present invention can also be applied to a copier having a scanner or a multi-function machine having these functions combined.

  The image forming apparatus 1 includes an intermediate transfer belt 40 at a substantially central portion inside thereof. The intermediate transfer belt 40 is an endless (endless) belt, and is looped around the outer periphery of the drive roller 12, the tension roller 13, and the driven rollers 14 and 15. The intermediate transfer belt 40 rotates counterclockwise as the driving roller 12 rotates. The tension roller 13 is urged by the spring 10 from the inside to the outside of the intermediate transfer belt 40. Therefore, tension is always applied to the intermediate transfer belt 40.

  Below the intermediate transfer belt 40, there are four imaging units 2Y, 2M, 2C, and 2K corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), and black (K). 40 are arranged side by side in this order. Each of the imaging units 2Y, 2M, 2C, 2K has a photoreceptor 21Y, 21M, 21C, 21K, respectively. Around each of the photoconductors 21Y, 21M, 21C, and 21K, charging devices 22Y, 22M, 22C, and 22K are sequentially arranged along a rotation direction at the time of image formation (also referred to as a positive rotation direction, clockwise in the figure), Exposure devices 23Y, 23M, 23C, and 23K, developing devices 24Y, 24M, 24C, and 24K, cleaning devices 25Y, 25M, 25C, and 25K, and erasers (static discharge devices) 26Y, 26M, 26C, and 26K are arranged. Yes. In the following description, subscripts representing the respective colors are omitted except when it is necessary to distinguish yellow (Y), magenta (M), cyan (C), or black (K).

  The charging device 22 is, for example, a scorotron, and uniformly charges the surface of the photoreceptor 21. The exposure device 23 exposes the charged photoreceptor 21 based on image data to be imaged. As a result, an electrostatic latent image based on the image data is formed on the photoreceptor 21. The developing device 24 converts the electrostatic latent image formed on the photoreceptor 21 into a visible image with toner. That is, a toner image is formed on the photoreceptor 21.

  The cleaning device 25 includes a strip-shaped cleaning blade 38. The cleaning blade 38 scrapes off residual toner remaining on the photosensitive member 21 after primary transfer described later. The eraser 26 includes an eraser lamp, and removes an afterimage of the electrostatic latent image on the surface of the photoconductor 21 after the primary transfer by irradiation of the eraser lamp.

  Further, as shown in FIG. 1, primary transfer rollers 30Y, 30M, and 30C for primary transfer, which will be described later, are located at positions facing the photoreceptors 21Y, 21M, 21C, and 21K with the intermediate transfer belt 40 interposed therebetween. 30K. A secondary transfer roller 16 for secondary transfer described later is pressed against the portion of the intermediate transfer belt 40 supported by the driving roller 12. A nip portion between the secondary transfer roller 16 and the intermediate transfer belt 40 becomes a secondary transfer region 17. In the secondary transfer region 17, the toner image transferred onto the intermediate transfer belt 40 is transferred to a sheet (final medium, recording medium) P.

  A paper feed cassette 91 is detachably disposed below the image forming apparatus 1. The paper P stored in a state of being stacked in the paper feed cassette 91 is pulled out one by one from the uppermost one by the rotation of the paper feed roller 92 and sent out to the transport path 93. The conveyance path 93 continues from the paper feed cassette 91 to the discharge tray 98 through the nip portion of the timing roller pair 94, the secondary transfer region 17, and the fixing device 95. The paper P sent out from the paper feed cassette 91 is conveyed to the timing roller pair 94 and is sent out to the secondary transfer area 17 at a predetermined timing.

  As shown in FIGS. 1 and 2, the fixing device 95 has a hollow cylindrical shape, a heating roller 96 (an example of a fixing heating member) 96 having a halogen heater 99 therein, and a driven rotation that is in pressure contact with the heating roller 96. And a pressure roller (rotating member) 97. The toner image is fixed to the paper P by passing the paper P on which the toner image is transferred by the secondary transfer through the nip formed by the heating roller 96 and the pressure roller 97. The fixing device 95 includes a temperature sensor 100 (corresponding to a first temperature measurement unit, hereinafter referred to as “surface temperature sensor 100”) that measures the temperature of the surface of the heating roller 96.

  In addition, the image forming apparatus 1 includes a control unit 70 that includes a CPU and controls the overall operation (see FIGS. 1 and 3). As shown in FIG. 3, in addition to the surface temperature sensor 100 described above, the control unit 70 includes a temperature sensor 101 (corresponding to a second temperature measurement unit, which corresponds to a second temperature measurement unit, which measures the temperature of the environment where the image forming apparatus 1 is installed). "Environmental sensor 101") is connected. The environment sensor 101 is less affected by the temperature of the heating roller 96 than the surface temperature sensor 100 and measures the temperature at a position that is more affected by the environment temperature. The environment sensor 101 may measure the temperature at a position that is not affected by the temperature of the heating roller 96 at all. Specific examples of the environmental temperature measured by the environmental sensor 101 include an in-machine temperature and a room temperature (room temperature) in which the image forming apparatus is installed.

  The control unit 70 also controls driving of the electric motor M that rotates the heating roller 96. Further, the control unit 70 controls the operation (lighting) of the halogen heater 99 via the heater control circuit 103 included in the low voltage power supply unit 102. The low-voltage power supply unit 102 converts power supplied from the external power source to the image forming apparatus 1 into a voltage suitable for the operation of the halogen heater 99 and the electric motor M, and supplies power to these. Note that the higher the voltage of the external power supply, the higher the voltage applied to the halogen heater 99.

  Next, an image forming operation of the image forming apparatus 1 having such a configuration will be briefly described. In the full color mode for outputting a color image, for example, when an image signal is input to the control unit 70 of the image forming apparatus 1 from an external device such as a personal computer, the control unit 70 outputs the image signal to yellow, cyan, magenta, and black. A digital image signal that has undergone color conversion is created, and based on the digital image signal, the exposure device 23 of each imaging unit 2 emits light to expose the photoconductor 21. Thereby, electrostatic latent images for the respective colors are formed on the surfaces of the photoreceptors 21Y, 21M, 21C, and 21K, respectively. Note that the surface of each photoconductor 21 is uniformly charged by the charging device 22 before exposure.

  The electrostatic latent images formed on the photoreceptors 21Y, 21M, 21C, and 21K are developed by the developing devices 24Y, 24M, 24C, and 24K, respectively, and become toner images of the respective colors. Each color toner image is rotated counterclockwise in FIG. 1 by applying a bias potential to the primary transfer rollers 30Y, 30M, 30C, and 30K (applying a bias potential opposite to the toner charging polarity). The images are sequentially transferred onto the intermediate transfer belt 40 and superimposed. As a result, a toner image is formed on the intermediate transfer belt 40 as a color image in which the toner images of the respective colors are superimposed. This is called primary transfer.

  The toner image transferred onto the intermediate transfer belt 40 reaches the secondary transfer area 17 as the intermediate transfer belt 40 moves. On the other hand, the paper P sent out from the paper feed cassette 91 to the transport path 93 is transported to the secondary transfer region 17 by the timing roller pair 94 in accordance with the timing when the toner image reaches the secondary transfer region 17. A large bias potential is applied to the secondary transfer roller 16 on the side opposite to the charged polarity of the toner as compared to the potential applied to the primary transfer roller 30. As a result, the toner image is transferred from the intermediate transfer belt 40 to the paper P in the secondary transfer region 17. This is called secondary transfer.

  The sheet P on which the toner image is transferred is sent to the fixing device 95 through the conveyance path 93. Therefore, the toner image is fixed on the sheet P by passing through a nip portion formed by the heating roller 96 and the pressure roller 97 heated by the lighting of the halogen heater 99. The paper P on which the toner image is fixed is discharged to a paper discharge tray 98.

  The residual toner remaining on the intermediate transfer belt 40 without being transferred onto the paper P is scraped off by the belt cleaning device 9 and removed from the outer peripheral surface of the intermediate transfer belt 40. Thereafter, the rotational drive of the photoreceptor 21 and the intermediate transfer belt 40 is stopped.

  Next, power supply control (voltage application control) to the halogen heater 99 will be described. As shown in FIG. 4, the control unit 70 controls voltage application to the halogen heater 99, that is, on / off of the halogen heater 99. Specifically, the control unit 70 decreases the surface temperature of the heating roller 96 measured by the surface temperature sensor 100 while the power supply to the halogen heater 99 is stopped, and falls below a predetermined reference temperature (lower limit value). When the voltage is applied to the halogen heater 99 (ie, the halogen heater 99 is turned on), the surface temperature of the heating roller 96 rises during the power supply to the halogen heater 99, and a predetermined reference temperature (upper limit) Value) or more, the voltage application to the halogen heater 99 is stopped (that is, the halogen heater 99 is turned off). As a result, the surface temperature of the heating roller 96 is kept in a temperature range suitable for fixing the toner image on the paper P. There is a time difference between when the halogen heater 99 is turned on and when the surface temperature of the heating roller 96 rises. In this embodiment, the lower limit value and the upper limit value are set to the same temperature, but the upper limit value and the lower limit value may be different as long as the upper limit value is not lower than the lower limit value.

  Incidentally, there is a relationship as shown in FIG. 5 between the length of the off time (seconds) of the halogen heater 99 and the magnitude of the inrush current (A) flowing through the halogen heater 99. That is, the longer the halogen heater 99 is off, the greater the inrush current flowing through the halogen heater 99. The inrush current is a large current that is instantaneously generated when a voltage is applied to the halogen heater 99. If the off time of the halogen heater 99 is long, the temperature of the filament of the halogen heater 99 decreases accordingly, and the electrical resistance of the filament becomes small. As a result, the inrush current increases. Specifically, in the example shown in FIG. 5, the inrush current becomes about 25 A 10 seconds after the voltage application to the halogen heater 99 is stopped. In addition, the rush current becomes about 45 A 100 seconds after the voltage application to the halogen heater 99 is stopped.

  Here, if the inrush current of the halogen heater 99 exceeds 25 A, the operation of peripheral devices may be affected, such as flickering. Therefore, in the image forming apparatus 1 of the embodiment, the control unit 70 controls power supply to the halogen heater 99 as shown in FIG. That is, in addition to the power supply control already described with reference to FIG. 4 (this is referred to as the first control), the control unit 70 turns off the halogen heater 99 (stops the power supply to the halogen heater 99). When the first period A of the predetermined length has elapsed, the halogen heater 99 is turned on over the second period B of the predetermined length even if the surface temperature of the heating roller 96 is not lower than the reference temperature. It is turned on (power is supplied to the halogen heater 99). This is called second control. By this second control, the filament temperature of the halogen heater 99 is prevented from excessively decreasing. The length of the first period A is determined so that a large inrush current does not flow so as to affect the peripheral devices such as flicker when power is supplied to the halogen heater 99 (specifically, Table 1 described later). reference).

  In the present embodiment, the second period B in which the halogen heater 99 is turned on is not long enough to change the surface temperature of the heating roller 96 (see FIG. 6). That is, it is a period shorter than the time difference from the start of power supply to the halogen heater 99 until the surface temperature of the heating roller 96 starts to rise. However, there is no problem even if the second period B is set to such a length that the surface temperature of the heating roller 96 slightly increases. However, if the second period B is excessively long, the surface temperature of the heating roller 96 may gradually rise away from the reference temperature. Therefore, it is necessary to set the length of the second period B to such an extent that such a problem does not occur.

  Of course, in the image forming apparatus 1 of the embodiment, the control unit 70 performs the second control, and when the surface temperature of the heating roller 96 becomes equal to or lower than the reference temperature, until the surface temperature of the heating roller 96 becomes equal to or higher than the reference temperature. (See period C in FIG. 6), the halogen heater 99 is turned on. When the surface temperature of the heating roller 96 becomes lower than the reference temperature during voltage application as the second control, the control unit 70 causes the halogen heater 99 to remain until the surface temperature of the heating roller 96 becomes higher than the reference temperature. Apply voltage to

The second control as described above is performed when the image is not formed, and is not performed when the image is formed. That is, the control unit 70 determines whether or not printing is currently being performed, and when it is being performed, only the first control is performed. On the other hand, when printing is not currently performed, the second control is performed in addition to the first control. The reason why the power supply control to the halogen heater 99 is changed depending on whether printing is currently being performed is as follows. That is, when printing is performed, as shown in FIG. 7, the time until the surface temperature of the heating roller 96 becomes equal to or lower than the reference temperature (period indicated by the symbol D in FIG. 7) is not printed. Compared to (see FIG. 4). This is because the heat of the heating roller 96 is taken away by the paper P (see FIG. 2). Therefore, when printing is performed, the voltage is not applied to the halogen heater 99 for a long time even if only the first control is performed. Therefore, the inrush current does not become excessive. Therefore, in the embodiment, the second control is performed only when it is not actually printing. Note that “when printing is actually in progress” means when printing is actually in progress, and includes when the printer is in normal operating mode and is not printing (when waiting). There is no concept.

  Here, in the image forming apparatus 1 of the embodiment, the control unit 70 performs the first operation according to the temperature of the installation environment of the image forming apparatus 1 (temperature measured by the environment sensor 101) and the voltage applied to the halogen heater 99. The length of the period A (the turn-off period A of the halogen heater 99) and the length of the second period B (the turn-on period B of the halogen heater 99) are automatically changed. Specifically, the control unit 70 changes the length of the turn-off period A and the turn-on period B according to the time determination table shown in Table 1 below. Note that the difference in the value of the applied voltage in Table 1 is a difference caused by the difference in the voltage value of the external power supply.

  As shown in Table 1, the controller 70 extends the extinguishing period A as the environmental temperature increases. This is because the filament temperature of the halogen heater 99 is less likely to decrease as the environmental temperature increases. Further, the control unit 70 lengthens the extinguishing period A as the applied voltage increases. This is due to the following reason. That is, the larger the voltage applied to the halogen heater 99, the smaller the current required for lighting the halogen heater 99 with a desired heater capacity. For this reason, the possibility of an excessive inrush current flowing is reduced. Therefore, the light extinction period A can be lengthened. Further, the control unit 70 increases the lighting period B as the extinguishing period A is longer. This is because the longer the turn-off period A, the more the temperature of the filament of the halogen heater 99 decreases.

  As described above, the control unit 70 automatically changes the length of the turn-off period A in the second control so that the halogen heater 99 is turned on as the second control with a minimum number of times. Further, by changing the length of the lighting period B in accordance with the length of the lighting period A in the second control, the filament temperature is raised within a range suitable for the purpose of preventing the occurrence of flicker and the like. Yes.

  Note that the temperature of the installation environment of the image forming apparatus 1 and the voltage applied to the halogen heater 99 vary greatly depending on, for example, the country in which the image forming apparatus 1 is used. Among countries where the image forming apparatus 1 is used (hereinafter referred to as “destination countries”), there are countries that require the manufacturer that the image forming apparatus 1 does not generate flicker or the like. Therefore, as shown in Table 2 below, the controller 70 may be configured to be able to perform the second control only when the ambient temperature and the applied voltage are specified. In such a configuration, the control unit 70 may automatically determine whether or not to execute the second control based on the temperature of the installation environment of the image forming apparatus 1 and the information on the voltage applied to the halogen heater 99. The service person who performs maintenance or the like of the image forming apparatus 1 may set whether or not to execute the second control. With this configuration, it is possible to obtain a product that conforms to the legal system of the destination country by simply setting the conditions (environment temperature and applied voltage) for executing the second control in accordance with the destination country of the image forming apparatus 1. . In the example shown in Table 2 below, the second control is set to be performed only when the environmental temperature is 15 ° C. or higher and lower than 25 ° C. and the applied voltage is 230 V (volts). Of course, the control unit 70 may be configured to perform the second control only when the applied voltage has a specific value without considering the environmental temperature. In this case, a condition (applied voltage) for executing the second control may be set in accordance with the applied voltage to the halogen heater 99 in the destination country having the above-mentioned legal system.

  As described above in detail, in the image forming apparatus 1 according to the embodiment, the control unit 70 determines that the halogen temperature is less than a predetermined lower limit value while the power supply to the halogen heater 99 is stopped. Power supply to the heater 99 is started, and during the power supply to the halogen heater 99, when the surface temperature of the heating roller 96 becomes equal to or higher than a predetermined upper limit value, the first control for stopping the power supply to the halogen heater 99 is performed. At the same time, when the first period A (see FIG. 6) having a predetermined length has elapsed after the supply of power to the halogen heater 99 is stopped, the surface temperature of the heating roller 96 is not less than a predetermined lower limit value. Also, the second control for supplying electric power to the halogen heater 99 is performed over the second period B (see FIG. 6) having a predetermined length. Therefore, no electric power is supplied to the halogen heater 99 for a long time. Therefore, the temperature of the filament of the halogen heater 99 is not excessively lowered and the electrical resistance of the filament is not extremely reduced. Accordingly, it is possible to prevent the operation of peripheral devices of the image forming apparatus 1 from being affected by an excessive inrush current.

  As a method for suppressing the inrush current, there is a conventional method in which a current flows through a resistor connected in series to the halogen heater only when energization of the halogen heater is started. However, this method is not suitable for products that have a short warm-up (shortening the warm-up time) due to power loss at the resistor. As another method, there is a method of reducing the current flowing through each halogen heater by connecting a plurality of halogen heaters in parallel. However, this method also leads to an increase in the size of the heating roller, so it is not suitable for products that are designed for short warm-up. In contrast, the image forming apparatus 1 according to the embodiment can prevent the occurrence of an excessive inrush current while enabling a short warm-up.

  In the image forming apparatus 1 according to the embodiment, the control unit 70 does not perform the second control when printing is actually performed. Therefore, it is possible to reduce the processing load on the control unit 70 when printing is actually performed.

  In the image forming apparatus 1 of the embodiment, the control unit 70 increases the first period A (see FIG. 6) as the temperature measured by the environment sensor 101 is higher. Further, the control unit 70 lengthens the first period A as the voltage applied to the halogen heater 99 is higher (see Table 1). Therefore, the number of times that the voltage is applied to the halogen heater 99 as the second control can be reduced within a range in which a problem such as flicker does not occur.

  In addition, embodiment mentioned above is only a mere illustration, and does not limit this invention at all. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, in the above embodiment, the control unit 70 is configured to automatically change the lengths of the turn-off period A and the turn-on period B. However, a service person who performs maintenance or the like of the image forming apparatus 1 performs the environmental temperature and halogen heater 99. The setting may be changed according to the applied voltage.

  In the embodiment, the second period B (lighting period B, see FIG. 6) in the second control is shorter than the lighting period C of the halogen heater 99 in the first control (the surface of the heating roller 96). It was long enough not to raise the temperature). The current that flows to the halogen heater 99 in the second period B was the same as the current that flows in the lighting period C. On the other hand, even if the second period B in the second control has the same length as the lighting period C in the first control, the current flowing to the halogen heater 99 in the second period B is smaller than the current flowing in the lighting period C. Good. Even if comprised in this way, it can adjust so that the surface temperature of the heating roller 96 may not rise too much by lighting of the halogen heater 99 in 2nd control.

  In the embodiment, the fixing device 95 includes the heating roller 96 including one halogen heater 99. However, the fixing device 95 may include a plurality of halogen heaters. In this case, the heater capacity of each halogen heater may be different. When the heater capacity of each halogen heater is different, the second control of the embodiment is performed for the halogen heater having the highest heater capacity, and the second control is not performed for the halogen heater having the smallest heater capacity. Also good. This is because a larger inrush current may flow in a halogen heater having a larger heater capacity, and at least the inrush current of the halogen heater that most easily affects the operation of peripheral devices can be suppressed.

  As a fixing device including a plurality of halogen heaters, for example, as illustrated in FIG. 8, a fixing device in which a plurality of halogen heaters 110, 111, and 112 are arranged in the width direction of the heating roller 96 </ b> A can be cited. In the case of a configuration like the fixing device 95A shown in FIG. 8, the halogen heater 111 located at the center in the width direction has a width corresponding to the paper width of B5 size, for example, and the three halogen heaters 110, 111, 112 are used. It is preferable that the total width dimension corresponds to, for example, the A4 size paper width. This is because only the halogen heater 111 needs to be lit when printing on B5 size paper. Of these halogen heaters 110, 111, and 112, when the heater capacity of the halogen heater 111 is larger than that of the other halogen heaters 110 and 112, the second control may be performed regarding the power supply control to the halogen heater 111. Further, when the heater capacity is large in the order of the halogen heater 111 at the center in the figure, the halogen heater 110 at the left in the figure, and the halogen heater 112 at the right in the figure, only the center halogen heater 111 may be configured to perform the second control. The second halogen heater 110 and the left halogen heater 110 may be configured to perform the second control.

  Further, the fixing device including a plurality of halogen heaters may be one in which two halogen heaters 113 and 114 having different width dimensions are arranged in the heating roller 96B as in the fixing device 95B shown in FIG. In this case, for example, the width dimension of the halogen heater 113 may correspond to the B5 size sheet width, and the width dimension of the halogen heater 114 may correspond to the A4 size sheet width. When the heater capacity of the halogen heater 114 is larger than the heater capacity of the halogen heater 113, the second control may be performed regarding the power supply control to the halogen heater 114.

  Further, the fixing device including a plurality of halogen heaters may include the halogen heater 115 not only in the heating roller 96 but also in the pressure roller 97A as in the fixing device 95C shown in FIG. When the heater capacity of the halogen heater 99 included in the heating roller 96 is larger than the heater capacity of the halogen heater 115 included in the pressure roller 97A, the second control may be performed regarding the power supply control to the halogen heater 99. In this case, the heating roller 96 and the pressure roller 97A correspond to the fixing heating member.

  In the embodiment, the image forming unit includes the imaging unit 2, the intermediate transfer belt 40, the primary transfer roller 30, and the secondary transfer roller 16. The control unit 70 of the embodiment constitutes a heater control unit.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 70 ... Control part 96 ... Heating roller (fixing heating member)
99 ... Halogen heater 100 ... Surface temperature sensor (first temperature measurement unit)
101 ... Environmental sensor (second temperature measurement unit)
P ... Recording medium

Claims (6)

An image forming unit for forming a toner image on a recording medium (hereinafter referred to as “image formation”);
A fixing heating member having a halogen heater, which is heated by the heat of the halogen heater and fixes the toner image on the recording medium in contact with the recording medium on which the toner image is formed ;
A first temperature measurement unit for outputting a temperature measurement value indicating the temperature of the fixing heating member;
In an image forming apparatus comprising a heater control unit for controlling power supply to the halogen heater ,
Compared to the first temperature measurement unit, the second temperature measurement unit outputs a temperature measurement value at a position less affected by the temperature of the fixing heating member and more influenced by the environmental temperature,
The heater control unit
While the power supply to the halogen heater is stopped, when the temperature measurement value of the first temperature measurement unit decreases and falls below a predetermined lower limit value, the power supply to the halogen heater is started.
During the power supply to the halogen heater, when the temperature measurement value of the first temperature measurement unit rises and exceeds a predetermined upper limit value that is not lower than the lower limit value, the power supply to the halogen heater is stopped. 1 control,
When the first period of a predetermined length has elapsed after the power supply to the halogen heater is stopped, a predetermined value is determined even if the temperature measurement value of the first temperature measurement unit is not less than or equal to the lower limit value. Performing a second control for supplying power to the halogen heater over a second period of length;
The image forming apparatus, wherein the first period is lengthened as the temperature measurement value of the second temperature measurement unit is higher. An image forming unit for forming a toner image on a recording medium (hereinafter referred to as “image formation”);
A fixing heating member having a halogen heater, which is heated by the heat of the halogen heater and fixes the toner image on the recording medium in contact with the recording medium on which the toner image is formed ;
A first temperature measurement unit for outputting a temperature measurement value indicating the temperature of the fixing heating member;
In an image forming apparatus comprising a heater control unit for controlling power supply to the halogen heater ,
The heater control unit
While the power supply to the halogen heater is stopped, when the temperature measurement value of the first temperature measurement unit decreases and falls below a predetermined lower limit value, the power supply to the halogen heater is started.
During the power supply to the halogen heater, when the temperature measurement value of the first temperature measurement unit rises and exceeds a predetermined upper limit value that is not lower than the lower limit value, the power supply to the halogen heater is stopped. 1 control,
When the first period of a predetermined length has elapsed after the power supply to the halogen heater is stopped, a predetermined value is determined even if the temperature measurement value of the first temperature measurement unit is not less than or equal to the lower limit value. Performing a second control for supplying power to the halogen heater over a second period of length;
In addition to supplying power from an external power source to supply power to the halogen heater,
The image forming apparatus, wherein the first period is lengthened as the voltage of the external power source is higher. An image forming unit for forming a toner image on a recording medium (hereinafter referred to as “image formation”);
A fixing heating member having a halogen heater, which is heated by the heat of the halogen heater and fixes the toner image on the recording medium in contact with the recording medium on which the toner image is formed ;
A first temperature measurement unit for outputting a temperature measurement value indicating the temperature of the fixing heating member;
In an image forming apparatus comprising a heater control unit for controlling power supply to the halogen heater ,
The heater control unit
While the power supply to the halogen heater is stopped, when the temperature measurement value of the first temperature measurement unit decreases and falls below a predetermined lower limit value, the power supply to the halogen heater is started.
During the power supply to the halogen heater, when the temperature measurement value of the first temperature measurement unit rises and exceeds a predetermined upper limit value that is not lower than the lower limit value, the power supply to the halogen heater is stopped. 1 control,
When the first period of a predetermined length has elapsed after the power supply to the halogen heater is stopped, a predetermined value is determined even if the temperature measurement value of the first temperature measurement unit is not less than or equal to the lower limit value. Performing a second control for supplying power to the halogen heater over a second period of length;
The image forming apparatus, wherein the second control is performed only when the voltage of the external power source is within a predetermined range. The image forming apparatus according to claim 3,
Compared to the first temperature measurement unit, the second temperature measurement unit outputs a temperature measurement value at a position less affected by the temperature of the fixing heating member and more influenced by the environmental temperature,
The image forming apparatus according to claim 1, wherein the heater control unit performs the second control only when the temperature measurement value of the second temperature measurement unit is within a predetermined range. An image forming unit for forming a toner image on a recording medium (hereinafter referred to as “image formation”);
A fixing heating member having a halogen heater, which is heated by the heat of the halogen heater and fixes the toner image on the recording medium in contact with the recording medium on which the toner image is formed ;
A first temperature measurement unit for outputting a temperature measurement value indicating the temperature of the fixing heating member;
In an image forming apparatus comprising a heater control unit for controlling power supply to the halogen heater ,
The fixing heating member includes a plurality of the halogen heaters having different heater capacities,
The heater control unit
While the power supply to the plurality of halogen heaters is stopped, when the temperature measurement value of the first temperature measurement unit decreases and falls below a predetermined lower limit value, power supply to the plurality of halogen heaters is started.
During the power supply to the plurality of halogen heaters, when the temperature measurement value of the first temperature measurement unit rises and exceeds a predetermined upper limit value that is not lower than the lower limit value, the power supply to the plurality of halogen heaters The first control to stop
When the first period of a predetermined length has elapsed after stopping the power supply to the plurality of halogen heaters, even if the temperature measurement value of the first temperature measurement unit is not less than or equal to the lower limit value, A power supply to one or more halogen heaters including a plurality of halogen heaters not including the smallest heater capacity and the largest heater capacity among the plurality of halogen heaters over a second period of a predetermined length is performed. 2. An image forming apparatus that performs two control . In the image forming apparatus according to any one of claims 1 to 5 ,
The image forming apparatus according to claim 1, wherein the heater controller does not perform the second control when image formation is being performed.

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