JP6578481B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus for fixing toner on a print medium by a fixing device including a first radiation heater and a second radiation heater having different heating widths.

  Conventionally, as the image forming apparatus as described above, for example, there is an apparatus described in Patent Document 1 below. A heating roller of a fixing device of this type of image forming apparatus (hereinafter referred to as a conventional image forming apparatus) includes a first radiant heater and a second radiant heater having a heating width wider than that of the first radiant heater.

Japanese Patent Application Laid-Open No. 2008-203685

  By the way, in the conventional image forming apparatus, generally, the second radiation heater having a wider heating width than the first radiation heater tends to be used more frequently than the first radiation heater. Therefore, the product life of the second radiation heater is shorter than that of the first radiation heater. Therefore, in order to extend the product life of the second radiation heater, the second radiation heater is preheated by turning on the first radiation heater prior to the lighting of the second radiation heater, and the second radiation heater is related to the product life of the second radiation heater. A method for reducing the inrush current when the radiation heater is turned on has been proposed.

  However, in the conventional image forming apparatus, even if the product life when the second radiant heater is turned on is extended by preheating, the accuracy related to the estimation of the deterioration amount of the second radiant heater for informing the user of the product life of the second radiant heater. There wasn't enough. Therefore, there has been a problem that the user must be requested to replace the fixing device earlier than the actual product life.

  An object of the present invention is to provide an image forming apparatus for fixing toner on a print medium by a fixing device including a first radiation heater and a second radiation heater having different heating widths. An object of the present invention is to provide an image forming apparatus having a product life estimation accuracy of a radiation heater higher than that of a conventional image forming apparatus.

An image forming apparatus according to an aspect of the present invention includes:
A fixing device having a first radiant heater and a second radiant heater for heating the print medium;
One of the first radiant heater and the second radiant heater is selected, and lighting and extinguishing of the selected radiant heater are controlled so that the temperature of the fixing device becomes a target value. A control unit for estimating the deterioration amount;
With
The width of heating the print medium by the second radiant heater is wider than that of the first radiant heater,
The controller pre-heats the second radiant heater by lighting the first radiant heater under a predetermined condition before lighting the second radiant heater. To reduce the amount of deterioration according to
It is characterized by.

  In the image forming apparatus according to an aspect of the present invention, when the amount of deterioration of the second radiant heater is estimated, the amount of deterioration is reduced according to the preheating state. This is to reflect the decrease in the inrush current to the second radiant heater in the estimation result of the deterioration amount when preheating is performed. Therefore, in the image forming apparatus according to one aspect of the present invention, since the reduction of the inrush current to the second radiant heater due to preheating is taken into account when estimating the deterioration amount of the second radiant heater, the conventional image forming apparatus. Compared with, the estimation accuracy of the product lifetime of the second radiation heater is high.

  According to the present invention, in the image forming apparatus in which the toner on the print medium is fixed by the fixing device including the first radiation heater and the second radiation heater having different heating widths, the second heating width is wider than that of the first radiation heater. The product life estimation accuracy of the radiation heater can be made higher than that of the conventional image forming apparatus.

1 is a diagram illustrating an overall configuration of an image forming apparatus according to an embodiment. It is a figure which shows the structure of the fixing device which concerns on one Example. It is a flowchart regarding lighting of the 2nd radiation heater which concerns on one Example. It is a flowchart regarding the preheating of the 2nd radiation heater which concerns on one Example. It is a flowchart regarding the preheating of the 2nd radiation heater which concerns on a modification.

(Schematic configuration of image forming apparatus, see FIG. 1)
In FIG. 1, an image forming apparatus 1 is, for example, a copying machine, a printer, a facsimile, or a multifunction machine having these functions, and prints an image on a sheet-like print medium M (for example, paper). For this purpose, the image forming apparatus 1 generally includes a paper feeding unit 2, a registration roller pair 3, an image forming unit 4, a fixing unit 5, a control unit 6, a power supply unit 7, an interface 8, A temperature sensor 9 is provided.

  A print medium M is stacked on the paper feed unit 2. The paper feed unit 2 sends out the print media M one by one to the transport path FP indicated by a broken line in FIG. The registration roller pair 3 is provided on the conveyance path FP and on the downstream side of the paper feeding unit 2. The registration roller pair 3 temporarily stops the print medium M sent out from the paper supply unit 2 and then sends it out to the secondary transfer area at a predetermined timing.

  The image forming unit 4 generates a toner image on the intermediate transfer belt by, for example, a well-known electrophotographic method and tandem method. Such a toner image is carried by the intermediate transfer belt and conveyed toward the secondary transfer area.

  The print medium M is sent from the registration roller pair 3 to the secondary transfer area, and the toner image is conveyed from the image forming unit 4. In the secondary transfer area, the toner image is transferred from the intermediate transfer belt to the print medium M.

  In the fixing device 5, the print medium M sent out from the secondary transfer region is introduced. The fixing device 5 fixes the toner on the printing medium M by heating and pressurizing the introduced printing medium M. The print medium M sent out from the fixing device 5 is discharged as a printed matter onto the tray of the image forming apparatus 1.

  In the control unit 6, the CPU executes a program stored in the ROM while using the RAM as a work area. The control unit 6 performs various controls, and energization control to the fixing device 5 is one of them. Specifically, the control unit 6 performs control so that the detection result of the temperature detection unit 55 (see FIG. 2) becomes the target temperature.

  The interface 8 is an operation unit for the user to directly instruct the operation of the image forming apparatus 1 and is, for example, a touch interface. The interface 8 also serves to notify the user of an abnormality in the image forming apparatus 1.

  The temperature sensor 9 is a thermistor or the like, and outputs a signal related to the ambient temperature in the image forming apparatus 1 to the control unit 6.

(Configuration of fixing device, see FIG. 2)
Next, the main part of the present embodiment, that is, the fixing device 5, the control unit 6, and the power supply unit 7 will be described. As shown in FIG. 2, the fixing device 5 includes a heating roller 51 and a pressure roller 52 that contact each other to form a nip, and includes the heating roller 51 and the pressure roller 52 that extend in the front-rear direction.

  The heating roller 51 has, for example, a cylindrical core bar extending in the front-rear direction of the image forming apparatus 1. The thickness of the cored bar is reduced to, for example, about 1 mm, and the outer diameter of the cored bar is decreased to, for example, about 25 mm, so that the heat capacity of the heating roller 51 is reduced.

  In the heating roller 51, a first radiant heater 53 and a second radiant heater 54 are built in the cored bar. Both the heaters 53 and 54 are heaters based on a light heating method such as a halogen heater. When an output voltage from the power supply unit 7 is applied to the heaters 53 and 54, a current flows through a filament made of tungsten, for example, and the filament generates heat and lights up. Here, as is well known, the resistivity of tungsten increases as the temperature increases. In other words, the heaters 53 and 54 have resistance-temperature characteristics in which the resistance value increases as the temperature increases.

  The first radiant heater 53 is shorter in the front-rear direction than the second radiant heater 54. Specifically, the first radiation heater 53 has a relatively short light emission length (for example, about 210 mm) in the front-rear direction. On the other hand, the second radiation heater 54 has a light emission length (for example, about 310 mm) longer in the front-rear direction than the first radiation heater 53. By incorporating both the heaters 53 and 54 in the heating roller 51, two types of heating widths which are relatively different in the front-rear direction are realized.

  Further, the second radiant heater 54 has larger power consumption (for example, 1000 W or more) than the first radiant heater 53 for the purpose of shortening the warm-up time, for example. Conversely, the first radiant heater 53 has lower power consumption (for example, 800 W or less) than the second radiant heater 54. Although both heaters 53 and 54 are switched on and off by the control of the drive elements 81 and 82, the second radiant heater 54 has a larger power consumption, so the influence of the inrush current is larger than that of the first radiant heater 53. receive.

  The pressure roller 52 and the heating roller 51 rotate based on a control signal from the control unit 6. When the printing medium M is fed into the nip, the printing medium M is pressed by both rollers 51 and 52 and heated by the heating roller 51. As a result, the toner is fixed on the print medium M.

  In the vicinity of the heating roller 51 described above, for example, temperature detection units 55 and 56 which are thermistors are provided. The temperature detector 55 outputs a signal related to the temperature at the center of the heating roller 51 (hereinafter simply referred to as temperature) to the controller 6, and the temperature detector 56 sends the temperature at the end of the heating roller 51 to the controller 6. Output.

  The power supply unit 7 rectifies the alternating current supplied from the commercial power supply by full-wave rectification, generates a plurality of DC voltages based on the rectified current, and supplies the DC voltage to the control unit 6 or a driving unit (not shown). . On the other hand, the power lines L (live) and N (neutral) of the power supply unit 7 are also used to light the first radiation heater 53 and the second radiation heater 54. The power supply line L is connected to one end of the heaters 53 and 54 via an excessive temperature rise prevention means 83 made of, for example, a thermostat. The excessive rise prevention unit 83 has a function of cutting off the power supply from the power supply unit 7 when the fixing device 5 is abnormally overheated.

  A driving element 81 and a driving element 82 are provided at L1 and L2, which are the other ends of the heaters 53 and 54, and are connected to the power supply line N. Both drive elements 81 and 82 include switching means such as SSR (Solid State Relay), and these drive elements are turned on / off under the control of the control unit 6, whereby the voltage applied to each of the heaters 53 and 54 is changed. On / off.

(Refer to Fig. 3 for lighting control of the second radiation heater)
In the image forming apparatus 1, the first radiant heater 53 is turned on and the second radiant heater is preheated under a predetermined condition before the second radiant heater is turned on. In the following, first, the main flow until the second radiation heater is turned on will be described.

  First, this control starts when the system related to the operation of the fixing device 5 is turned on, that is, when the power of the image forming apparatus 1 is turned on.

  In the first step MS01 of this control, the control unit 6 confirms information related to the preheating frequency recorded in the storage means in the control unit 6. The frequency of this preheating is a reference for determining how much the second radiant heater is preheated when the temperature of the center of the heating roller 51 described later is within a specific temperature range. The frequency of preheating can be selected by the user using the image forming apparatus 1 via the interface 8.

  In the second step MS02, the control unit 6 checks the value of the life counter indicating the deterioration amount of the second radiation heater 54, and determines whether or not the value of the life counter is 20000 or more. The life counter is a part of the control unit 6, and a value obtained by adding a value corresponding to a preheating state of the second radiant heater 54 to a value indicating the lighting time of the second radiant heater 54 is used as the second radiant heater. It counts as the amount of degradation. If the control unit 6 determines Yes in the second step MS02, the control proceeds to the third step MS03, and if it determines No, the control proceeds to the fourth step MS04.

  In the third step MS03, the control unit 6 displays on the interface 8 that the time for replacement of the fixing device 5 including the second radiation heater 54 has arrived. Thereafter, the present control proceeds to the fourth step MS04.

  In 4th step MS04, the control part 6 determines whether the temperature of the heating roller 51 center part detected by the temperature detection part 55 is 170 degrees C or less. When it is determined that the temperature at the center of the heating roller 51 is 170 ° C. or lower, the present control proceeds to the fifth step MS05. When it is determined that the temperature is higher than 170 ° C., the present control is performed at the fourth step MS04. stand by.

  In 5th step MS05, the control part 6 determines whether the temperature of the center part of the heating roller 51 detected by the temperature detection part 55 is 10 degrees C or less. If it is determined that the temperature at the center of the heating roller 51 is 10 ° C. or less, the control proceeds to the sixth step MS06, and if it is determined that the temperature is higher than 10 ° C., the first step SS01 of the preheating flow. Proceed to The preheating flow will be described after the description of the main flow.

  In the sixth step MS06, the control unit 6 turns on the first radiation heater 53. That is, preheating of the second radiant heater 54 by the first radiant heater 53 is started. This preheating is performed regardless of the setting of the preheating frequency by the user.

  In the seventh step MS07, the control unit 6 starts the timer T1. The timer T1 measures the lighting time of the first radiation heater 53 with the time when the first radiation heater 53 is lit as a reference time.

  In the eighth step MS08, the control unit 6 determines whether or not the measurement time by the timer T1 has passed 2 seconds. When it is determined that 2 seconds have elapsed, the present control proceeds to the ninth step MS09, and when it is determined that 2 seconds have not elapsed, the present control waits at the eighth step MS08.

  In the ninth step MS09, the control unit 6 turns off the first radiation heater 53.

  In the tenth step MS10, the control unit 6 turns on the second radiation heater 54.

  In the eleventh step MS11, the control unit 6 increases the count number of the life counter by 30. The count number of the life counter related to preheating of the second radiant heater 54 is a value obtained by multiplying the preheating reference value by a reduction coefficient corresponding to each preheating state. In the present embodiment, the reference value is 10, and the reduction coefficient corresponding to the preheating performed in the sixth step MS06 to the ninth step MS09 is 3. Therefore, by multiplying these, the count number becomes 30 counts.

  In the twelfth step MS12, the control unit 6 starts the timer T2. The timer T2 measures the lighting time of the second radiation heater 54 from the time when the timer T2 is activated.

  In 13th step MS13, the control part 6 determines whether the measurement time by the timer T2 passed 1 second. When it is determined that 1 second has elapsed, the present control proceeds to the 14th step MS14, and when it is determined that 1 second has not elapsed, the present control waits at the 13th step MS13.

  In the 14th step MS14, the controller 6 determines whether or not the temperature at the center of the heating roller 51 is 175 ° or higher. When it is determined that the temperature at the center of the heating roller 51 is less than 175 ° C., the present control proceeds to the fifteenth step MS15. move on.

  In the fifteenth step MS15, the control unit 6 increases the count number of the life counter by one. That is, in this embodiment, it is determined that the deterioration of the second radiant heater 54 has advanced by one count per second of lighting of the second radiant heater 54. After the end of the fifteenth step MS15, the control returns to the twelfth step MS12 after resetting the timer T2.

  In the sixteenth step MS16, the control unit 6 turns off the second radiation heater 54. Thereafter, the present control returns to the second step MS02 and repeats the flow up to the 16th step. This is the end of the description of the main flow.

(Refer to Fig. 4 for preheating control of the second radiant heater)
As described above, when it is determined in the fifth step MS05 of the main flow that the temperature of the central portion of the heating roller 51 is higher than 10 ° C., the process proceeds to the first step SS01 of the preheating flow.

  In the first step SS01 of the preheating flow, the control unit 6 confirms the value of the preheating frequency counter and determines whether or not the value n of the preheating frequency counter has reached a predetermined value N. The preheating frequency counter is a part of the control unit 6 and counts a value for determining whether or not to preheat the second radiant heater. Here, the predetermined value N can be selected by the user via the interface 8 as the preheating frequency. For example, if the user selects the occurrence frequency of preheating of the second radiation heater 54 as 1/5, 5 is substituted for the predetermined value N. If the control unit 6 determines Yes in the first step SS01, the control proceeds to the second step SS02. If the control unit 6 determines No, the control proceeds to the third step SS03.

  In 2nd step SS02, the control part 6 clears the value of a preheating frequency counter, and returns it to 0. When this step ends, the present control proceeds to the fourth step SS04.

  In the third step SS03, the control unit 6 increments the count number of the preheating frequency counter by one. When this step ends, the present control proceeds to 18th step SS18.

  In 4th step SS04, the control part 6 determines whether the temperature difference of the center part of the heating roller 51 and the edge part of this heating roller 51 is 5 degreeC or more. When it is determined that the temperature difference is less than 5 ° C., the present control proceeds to the fifth step SS05, and when it is determined that the temperature difference is 5 ° C. or more, the control proceeds to the eleventh step SS11.

  In the fifth step SS05, the control unit 6 turns on the first radiation heater 53. That is, preheating of the second radiant heater 54 by the first radiant heater 53 is started.

  In the sixth step SS06, the control unit 6 starts the timer T1.

  In the seventh step SS07, the control unit 6 determines whether or not the measurement time by the timer T1 has passed 2 seconds. When it is determined that 2 seconds have elapsed, the present control proceeds to the eighth step SS08, and when it is determined that 2 seconds have not elapsed, the present control waits at the seventh step SS07.

  In the eighth step SS08, the control unit 6 turns off the first radiation heater 53.

  In 9th step SS09, the control part 6 makes the 2nd radiation heater 54 light.

  In the tenth step SS10, the control unit 6 increases the count number of the life counter by three. And when the control part 6 increases the count number of a lifetime counter, this control will progress to 12th step MS12 of a main flow. Note that the reduction coefficient corresponding to the preheating performed in the fifth step SS05 to the eighth step SS08 of the preheating flow is 0.3. Therefore, the count number is 3 by multiplying 0.3, which is the reduction coefficient, by 10, which is the preheating reference value.

  In 11th step SS11, the control part 6 determines whether the temperature difference of the center part of the heating roller 51 and the edge part of this heating roller 51 is 10 degreeC or more. When it is determined that the temperature difference is less than 10 ° C., the present control proceeds to the twelfth step SS12, and when it is determined that the temperature difference is 10 ° C. or more, the control proceeds to the eighteenth step SS18.

  In the twelfth step SS12, the control unit 6 turns on the first radiation heater 53. That is, preheating of the second radiant heater 54 by the first radiant heater 53 is started.

  In the thirteenth step SS13, the control unit 6 starts the timer T1.

  In 14th step SS14, the control part 6 determines whether the measurement time passed 1 second by the timer T1. If it is determined that one second has elapsed, the present control proceeds to the fifteenth step SS15. If it is determined that one second has not elapsed, the present control waits in the fourteenth step SS14.

  In the fifteenth step SS15, the control unit 6 turns off the first radiation heater 53.

  In the sixteenth step SS16, the control unit 6 turns on the second radiation heater 54.

  In the 17th step SS17, the control unit 6 increases the count number of the life counter by 6. And when the control part 6 increases the count number of a lifetime counter, this control will progress to 12th step MS12 of a main flow. In addition, the reduction coefficient corresponding to the preheating performed in 12th step SS12 to 15th step SS15 of the preheating flow is 0.6. Therefore, the count number is 6 by multiplying the reduction coefficient of 0.6 by 10 which is the preheating reference value.

  In 18th step SS18, the control part 6 determines whether 10 second or more has passed since the last lighting of the 2nd radiation heater 54. FIG. If 10 seconds or more have not elapsed since the last lighting of the second radiation heater 54, the present control proceeds to the 19th step SS19, and if it is determined that it is 10 seconds or more, the control proceeds to the 21st step SS21. .

  In the 19th step SS19, the controller 6 turns on the second radiation heater 54.

  In the twentieth step SS20, the control unit 6 increases the count number of the life counter by ten. And when the control part 6 increases the count number of a lifetime counter, this control will progress to 12th step MS12 of a main flow.

  In 21st step SS21, control part 6 judges whether 30 seconds or more have passed since lighting of the 2nd radiation heater 54 last time. If 30 seconds or more have not elapsed since the last lighting of the second radiation heater 54, the present control proceeds to the 22nd step SS22, and if it is determined that it is 30 seconds or more, the control proceeds to the 28th step SS28. .

  In the 22nd step SS22, the controller 6 turns on the first radiation heater 53. That is, preheating of the second radiant heater 54 by the first radiant heater 53 is started.

  In the 23rd step SS23, the controller 6 starts the timer T1.

  In the 24th step SS24, the controller 6 determines whether or not the measurement time has passed 2 seconds by the timer T1. When it is determined that 2 seconds have elapsed, the present control proceeds to the 25th step SS25, and when it is determined that 2 seconds have not elapsed, the present control waits at the 24th step SS24.

  In the 25th step SS25, the control unit 6 turns off the first radiation heater 53.

  In the 26th step SS26, the controller 6 turns on the second radiation heater 54.

  In the 27th step SS27, the control unit 6 increases the count number of the life counter by 12. And when the control part 6 increases the count number of a lifetime counter, this control will progress to 12th step MS12 of a main flow. In addition, the reduction coefficient corresponding to the preheating performed in the 22nd step SS22 to the 25th step SS25 of the preheating flow is 1.2. Therefore, the count number becomes 12 by multiplying the reduction factor of 1.2 by 10 which is the preheating reference value.

  In the 28th step SS28, the control unit 6 turns on the first radiation heater 53. That is, preheating of the second radiant heater 54 by the first radiant heater 53 is started.

  In the 29th step SS29, the control unit 6 starts the timer T1.

  In the 30th step SS30, the control unit 6 determines whether or not the measurement time by the timer T1 has passed 2 seconds. When it is determined that 2 seconds have elapsed, the present control proceeds to the 31st step SS31. When it is determined that 2 seconds have not elapsed, the present control waits at the 30th step SS30.

  In the 31st step SS31, the control unit 6 turns off the first radiation heater 53.

  In the thirty-second step SS32, the controller 6 turns on the second radiation heater 54.

  In the thirty-third step SS33, the control unit 6 increments the count number of the life counter by 20. And when the control part 6 increases the count number of a lifetime counter, this control will progress to 12th step MS12 of a main flow. The reduction coefficient corresponding to the preheating performed in the 28th step SS28 to the 31st step SS31 of the preheating flow is 2. Therefore, the count number becomes 20 by multiplying 10 of the preheating reference value by 2 of this reduction coefficient. This is the end of the description of the preheating flow.

(effect)
In the image forming apparatus 1 according to the embodiment, the count number of the life counter related to the preheating of the second radiation heater 54 is changed according to the preheating state of the second radiation heater 54. For example, when the center temperature of the heating roller 51 is 10 ° C. or more and 170 ° C. or less and the temperature difference between the center portion and the end portion of the heating roller 51 is 5 ° C. or less, preheating is performed for 2 seconds, Increase the count by 3. On the other hand, when the second radiant heater 54 is turned on without preheating, the count of the life counter is incremented by ten. Thus, by changing the count number of the life counter according to the preheating state, in the image forming apparatus 1, when estimating the deterioration amount of the second radiant heater 54, the second radiant heater according to the preheating state. 54 is estimated by reducing the deterioration amount. Thereby, the reduction | decrease of the inrush current to the 2nd radiation heater 54 by preheating can be reflected in the estimation result of the deterioration amount of this 2nd radiation heater. As described above, in the image forming apparatus 1 according to the embodiment, when the amount of deterioration of the second radiation heater 54 is estimated, the reduction of the inrush current to the second radiation heater 54 due to preheating is taken into account. Compared with the image forming apparatus, the estimation accuracy of the product life of the second radiation heater 54 is high. As a result, the notification of the replacement time of the fixing device 5 to the user is not as early as the conventional image forming apparatus, and the product life of the fixing device 5 is substantially extended.

  There are a plurality of mitigation factors used when estimating the amount of deterioration related to preheating depending on the preheating time, the temperature of the central portion of the heating roller 51 before preheating, and the like. Thereby, the lifetime of the 2nd radiation heater 54 can be estimated more correctly compared with the case where there is only one reduction coefficient concerning preheating.

  By the way, when preheating the second radiant heater 54, it takes some time to form an image due to the time required for the preheating and the cooling for equalizing the temperature deviation of the surface of the heating roller 51 caused by the preheating. Therefore, if the second radiant heater 54 is preheated every time when the heating roller 51 is in a predetermined temperature range, the user is inconvenienced. However, in the image forming apparatus 1, it is possible for the user to select the frequency of preheating. Thereby, it is possible to ensure convenience when the user uses the image forming apparatus 1.

  However, when the temperature of the heating roller 51 is extremely low, for example, when the temperature is 10 ° C. or less in the present embodiment, the second radiant heater 54 is preheated regardless of the preheating frequency set by the user. The reason for performing such control is as follows. When the temperature of the heating roller 51 is very low, that is, when the temperature of the second radiant heater 54 is extremely low, the inrush current to the second radiant heater 54 becomes extremely large. If the second radiant heater 54 is turned on in this state, not only will the deterioration of the second radiant heater 54 be greatly advanced, but other electric appliances connected to the same power supply system as the second radiant heater 54 may have insufficient current. Affected. In order to prevent such a situation, in the image forming apparatus 1, when the temperature of the heating roller 51 is extremely low, the second radiant heater 54 is preheated regardless of the preheat occurrence frequency set by the user.

  In addition to this, when the lighting interval to the second radiant heater 54 is longer than a predetermined time, even if it is 10 seconds or longer in this embodiment, the second radiant heater 54 is used regardless of the preheating occurrence frequency set by the user. Preheat to. This is because when the lighting interval to the second radiant heater 54 is longer than a predetermined time, it can be estimated that the temperature of the second radiant heater 54 is low, the inrush current to the second radiant heater 54 is large, and the second This is because it is considered that the deterioration of the radiant heater 54 is greatly advanced. Therefore, in the image forming apparatus 1, even when the lighting interval to the second radiation heater 54 is longer than a predetermined time, the second radiation heater 54 is preheated regardless of the preheating occurrence frequency set by the user. Thus, the product life of the second radiation heater 54 is secured.

  In the image forming apparatus 1, when the central portion of the heating roller 51 is in a predetermined temperature range, the temperature between the central portion and the end portion of the heating roller 51 is 10 ° C. or higher and 170 ° C. or lower in this embodiment. When the difference is a predetermined value or more, for example, when the difference is 10 ° C. or more, the second radiant heater 54 is not preheated. This is because the productivity of the image forming apparatus 1 is taken into consideration. If the temperature deviation of the surface of the heating roller 51 due to preheating becomes too large, it takes a long time for cooling to equalize the temperature of the surface. Thereby, productivity of image formation is deteriorated. Therefore, in the image forming apparatus 1, when the temperature difference between the center portion and the end portion of the heating roller 51 is equal to or greater than a predetermined value, the second radiant heater 54 is not preheated in order to maintain desired productivity.

  In addition, in the image forming apparatus 1, when the temperature difference between the center portion and the end portion of the heating roller 51 is within a predetermined range, for example, when the temperature difference is 5 ° C. or higher and lower than 10 ° C., This is performed shorter than the case where the temperature difference between the center and the end of the heating roller 51 is less than 5 ° C. Thus, by changing the preheating time according to the temperature difference between the center portion and the end portion of the heating roller 51, the image forming apparatus 1 can extend the image forming productivity and the life of the second radiant heater 54. Can keep balance with.

(Modification example See FIG. 5)
The difference between the image forming apparatus 1A as the modification and the image forming apparatus 1 as an embodiment is that there are a plurality of counts of the life counter when the second radiant heater 54 is not preheated.

  Specifically, in the preheating flow of the image forming apparatus 1A which is a modified example, as shown in FIG. 5, between the 19th step SS19 and the 20th step SS20, the radiation heater 54 is turned on from the previous lighting. Determination step EXS1 about the lighting interval until is inserted. For example, it is a determination step of whether or not 5 seconds or more have elapsed from the previous lighting of the second radiation heater 54 to the current lighting. If 5 seconds or more have not elapsed, the count number of the life counter is incremented by 8, and if 5 seconds or more have elapsed, the count number of the life counter is incremented by 10.

  The reason for changing the count according to the lighting interval of the second radiant heater 54 as described above is that when the lighting interval of the second radiant heater 54 is short, the temperature of the second radiant heater is not so low. Even if there is no, the inrush current to the second radiation heater 54 is not so high. That is, the deterioration of the second radiant heater 54 does not proceed greatly even without preheating. Therefore, in the image forming apparatus 1A, by performing the determination step EXS1 as described above, if the lighting interval of the second radiant heater 54 is short, it is assumed that preheating is performed even if preheating is not performed, and the amount of deterioration The accuracy of the estimation is improved.

(Other examples)
The image forming apparatus according to the present invention is not limited to the above embodiment, and can be variously modified within the scope of the gist. For example, instead of the temperature at the center of the heating roller 51 when determining whether or not to preheat, the atmospheric temperature in the apparatus detected by the temperature sensor 9 in the image forming apparatus 1 may be used. In addition, the preheating of the second radiation heater may be performed by changing the preheating temperature with a constant preheating time, and estimating the deterioration amount due to the reduction coefficient corresponding to the preheating temperature. Further, the count number of the life counter for estimating the arrival of the replacement time of the fixing device 5 including the second radiation heater 54 is not limited to 20000, and may be an arbitrary value corresponding to each product. In addition to this, the user may be able to select the preheating occurrence frequency, for example, 4/5, that is, N-1 / N. In this case, the flow proceeds from the second step SS2 to the eighteenth step SS18 of the preheating flow, and proceeds from the third step SS3 to the fourth step SS4. And you may combine each Example.

  As described above, the present invention is effective for an image forming apparatus that fixes toner on a print medium by a fixing device including a first radiation heater and a second radiation heater having different heating widths, and in particular, the first radiation heater. The second radiation heater having a wider heating width is superior in that the product life estimation accuracy can be made higher than that of the conventional image forming apparatus.

1, 1A Image forming apparatus 5 Fixing device 6 Control unit 53 First radiation heater 54 Second radiation heater

Claims (10)

A fixing device having a first radiant heater and a second radiant heater for heating the print medium;
One of the first radiant heater and the second radiant heater is selected, and lighting and extinguishing of the selected radiant heater are controlled so that the temperature of the fixing device becomes a target value. A control unit for estimating the deterioration amount;
With
The width of heating the print medium by the second radiant heater is wider than that of the first radiant heater,
The controller pre-heats the second radiant heater by lighting the first radiant heater under a predetermined condition before lighting the second radiant heater. To reduce the amount of deterioration according to
An image forming apparatus. The estimation of the deterioration amount is estimated as a total value obtained by adding a value corresponding to a preheating state to a value proportional to the lighting time of the second radiation heater,
The image forming apparatus according to claim 1. There are a plurality of preheating times and preheating temperatures in the preheating of the second radiation heater,
The value corresponding to the preheating condition is a value obtained by multiplying a predetermined value by a reduction coefficient,
A plurality of the reduction factors corresponding to the preheating time and the preheating temperature,
The image forming apparatus according to claim 2. The user can select the frequency of preheating of the second radiant heater,
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. When the second radiant heater is not lit for a predetermined time or more, the control unit preheats the second radiant heater regardless of a selection result of a preheat generation frequency of the second radiant heater by a user. ,
The image forming apparatus according to claim 4. The fixing device further includes a rotating body that is heated by radiant heat from the first radiant heater and the second radiant heater, and transmits the heat obtained by the heating to the print medium by contacting the print medium.
The controller does not preheat the second radiant heater when the temperature difference between the central portion and the end of the rotating body exceeds a predetermined value;
The image forming apparatus according to claim 1, wherein: The fixing device further includes a rotating body that is heated by radiant heat from the first radiant heater and the second radiant heater, and transmits the heat obtained by the heating to the print medium by contacting the print medium.
The control unit shortens the time for preheating the second radiant heater when the temperature difference between the center and the end of the rotating body exceeds a predetermined value.
The image forming apparatus according to claim 1, wherein: Even if the control unit turns on the second radiation heater without preheating, the second radiation heater before the current lighting of the second radiation heater and the current lighting of the second radiation heater are turned on. When the lighting interval with the lighting of is shorter than a predetermined time, the deterioration amount is estimated on the assumption that the second radiation heater is preheated before the second radiation heater is turned on.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. A plurality of the reduction factors corresponding to the ambient temperature around the fixing device at the time of starting the fixing device;
The image forming apparatus according to 請 Motomeko 3 characterized. The fixing device further includes a rotating body that is heated by radiant heat from the first radiant heater and the second radiant heater, and transmits the heat obtained by the heating to the print medium by contacting the print medium.
A plurality of the reduction factors corresponding to the temperature of the rotating body before the preheating of the second radiation heater,
The image forming apparatus according to 請 Motomeko 3 characterized.

Images