JP2004286936A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform stable fixation control by suppressing various external factors without using any complicated control and to deter defects in fixation during state transition from a standby state to an image formation state as to an image forming apparatus equipped with a fixing device which heats and fixes a toner image on a transfer material by using a fixing member which has a plurality of fixing heaters with different light distributions inside and is small in thermal capacity. <P>SOLUTION: The image forming apparatus prepares a table for determining a heater to be turned on and a table for determining its turn-on intervals and determines conditions regarding control over an electrification state by a driving control means based upon setting contents of the tables, but complements an abrupt drop caused by rotation of a fixing roller for the start of image forming operation, i.e. a deficiency in heating value in real time by selecting a heating pattern for turning on fixing heaters at the same time as target control temperature is varied under simple constitution wherein the target control temperature is only changed from standby temperature to image formation temperature at state transition time t1 from the standby state to the image formation state. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic copying machine, a printer, a facsimile machine, and a fixing device that heats and fixes a toner image on a transfer material using a fixing member having a plurality of fixing heaters having different light distributions. The present invention relates to an image forming apparatus such as a multifunction peripheral (MFP).
[0002]
[Prior art]
2. Description of the Related Art In recent years, from the viewpoint of improving power energy consumption efficiency and operability and convenience, many image forming apparatuses have a fixing heater with a reduced warm-up time. Here, in order to shorten the warm-up time, a thin fixing roller having a small heat capacity and a small thermal resistance, a high-power halogen heater or a halogen heater having a plurality of (two) heaters are often used. For example, see Patent Document 1).
[0003]
Various control examples of this type of fixing device have been proposed. For example, according to the temperature control device of the fixing device disclosed in Patent Document 2, by adjusting the initial correction value in accordance with the initial detection temperature of the heat roller before the start of the warm-up control process and the number of energizations to the heater, the target and the target are adjusted. The control temperature is corrected to compensate for a fixing failure (insufficient amount of heat) at startup. Further, according to the temperature control device of the fixing device disclosed in Patent Document 3, the heater is temporarily turned off during the warm-up process in order to reduce the temperature drop due to the side effect of the overshoot. Similarly, according to the fixing device of Patent Document 4, a heater-off process is added to the control unit in order to suppress overshoot. Further, according to the fixing device of Patent Document 5, the energization cycle is set to a predetermined time or more as a measure against voltage flicker.
[0004]
[Patent Document 1]
JP 08-220932 A
[Patent Document 2]
JP 07-152276 A
[Patent Document 3]
JP-A-07-114289
[Patent Document 4]
JP-A-10-039678
[Patent Document 5]
JP-A-09-244463
[0005]
[Problems to be solved by the invention]
As exemplified in Patent Documents 2 to 5 described above, there are various control examples related to the fixing device. However, a fixing device described in Patent Document 1, particularly, a plurality of fixing heaters having different light distribution characteristics is used. In the case of a fixing device of the type provided, the consideration and examination are insufficient, stable temperature control cannot be performed, and the control is complicated.
[0006]
That is, in the case of a fixing device as disclosed in Patent Document 1, since the heat capacity is small and the thermal resistance is small, the state greatly varies depending on the environmental change and the size, thickness, and type of the sheet with respect to paper passing. However, in the related art, such fluctuation cannot be suppressed without using complicated control. Further, in the control of the fixing device having such a large variation element, a significant overshoot occurs unless the transition of the temperature change or the correlation between the output and the actual temperature change is observed. In the prior art, it cannot be suppressed without providing a special detecting means and using complicated control. Furthermore, when controlling a plurality of fixing heaters having different light distributions, it is desirable to be able to easily change even if there is a change of a part of a fixing device, an addition of a specification, a countermeasure for a defect, and the like. However, this point is also difficult to deal with in the case of the conventional technology.
[0007]
For example, the target control temperature is corrected by adjusting the initial correction value in accordance with the initial detection temperature of the heat roller before the start of the warm-up control process and the number of times of power supply to the heater, and the fixing failure at startup ( The case of Patent Document 2 which compensates for the lack of heat will be described in more detail. In this patent document 2, when examined in more detail, the control temperature TC is set by the initial correction amount: D1, the sheet passing correction amount: D2, and the environmental correction amount: D3, and the correction amount is determined by the number of energization times and the accumulated energization time. Where D1 << D2 and D3, where D2 is different depending on the paper type and paper size, and D3 is much larger than the environment due to variations in heater capacity and power supply conditions. It is.
[0008]
Therefore, such control is applicable to a roller configuration having a relatively small heat capacity, and has a small heat capacity and a large heat flow by providing a plurality of heaters, as the object of the present invention. In the case of an image forming apparatus using a fixing device, such a control method cannot often cope with the control method, and is insufficient. That is, in the case of Patent Document 2, the control temperature TC is operated / corrected by using a “correction amount” in order to maintain the roller temperature (fixing / pressure roller) within a certain temperature, so that the amount of heat does not become insufficient on the paper surface. Due to changes in the relationship between this part (control temperature TC operation and roller temperature (fixing / pressure roller)) and changes in prerequisites, the system easily falls into a situation where the correction amount is insufficient or overcorrected. It is.
[0009]
In general, if the heat capacity is large enough to continuously use such correction in a plurality of image forming operations, it is possible to cope with the conventional technique as disclosed in Japanese Patent Application Laid-Open No. H10-157, but a predetermined amount of the initial correction amount may be used. It is described that the correction amount is changed by a value (threshold), and as a practical problem, it is described in Japanese Patent Application Laid-Open No. H11-157400 that print output by developing a large-capacity bitmap image is an intermittent image forming operation at substantially equal intervals. Since the prediction of the pressure roller temperature becomes extremely uncertain and requires a correction process, there is a high possibility of overcorrection.
[0010]
Further, even if the amount of heat of the fixing heater differs due to the difference in the rated voltage and the power supply situation in each country, the correction is performed with a unique correction amount, so that the insufficient amount of heat cannot be compensated for in the first half of the image forming operation.
[0011]
As a result, in an image forming apparatus capable of shortening the warm-up time, the heat capacity for continuously using the correction in a plurality of image forming operations is not large, so that it is difficult to cope with the conventional technique as disclosed in Patent Document 2. .
[0012]
An object of the present invention is to provide an image forming apparatus having a fixing device for heating and fixing a toner image on a transfer material by using a fixing member having a small heat capacity and having a plurality of fixing heaters having different light distributions. It is intended to perform stable fixing control while suppressing various external factors without using control, and to suppress fixing defects at the time of state transition from the standby state to the image forming state.
[0013]
In addition, an object of the present invention is to suppress a problem caused by an overshoot of the heater temperature due to a state transition from an image forming state to a standby state.
[0014]
Further, it is intended to improve user operability and productivity by keeping the warm-up processing to a minimum necessary processing time.
[0015]
In addition, it is necessary to easily perform fixing control even when a fixing component is changed, a specification is added, or a power supply situation is different.
[0016]
[Means for Solving the Problems]
2. The image forming apparatus according to claim 1, further comprising a fixing device that heats and fixes the toner image on the transfer material using a fixing member having a plurality of fixing heaters having different light distributions. A temperature sensor provided in accordance with the light distribution for each time to detect a temperature around the fixing member, a drive control means for controlling an energization state to the fixing heater, and sampling an output of the temperature sensor at predetermined time intervals. Sampling means for acquiring temperature data around the fixing member, and a lighting heater determination table to be turned on among the plurality of fixing heaters based on the temperature data sampled by the sampling means and a target control temperature. Reference is made to at least two or more tables, and the control of the energization state by the drive control means according to the table setting contents. Determining means for determining a condition; and target control temperature changing means for changing the target control temperature from a standby temperature to a temperature higher than the standby temperature when the image forming apparatus transitions from a standby state to an image forming state. .
[0017]
Therefore, basically, in the case of a fixing device that heats and fixes a toner image on a transfer material by using a fixing member having a small heat capacity and a plurality of fixing heaters having different light distributions, the characteristics of the fixing device cause environmental fluctuation and Although the state greatly varies depending on the size, thickness, and type of paper to be passed, at least two or more tables including a lighting heater determination table to be turned on are prepared in advance, and the temperature sampling result and the target control temperature are set. By referring to these tables on the basis of the above and determining the conditions related to the control of the energization state by the drive control means based on the contents of the tables, the fixing control can be stably performed with simple control, and Even when a part is changed or a specification is added, it is possible to easily and properly deal with it simply by changing the setting contents of the table. In addition, at the time of the state transition from the standby state to the image forming state, the image forming operation can be performed without changing the setting contents of the table by the simple control of changing the target control temperature from the standby temperature to a temperature higher than the standby temperature. A sudden decrease in the temperature of the fixing member caused by rotation of the fixing member toward the start = insufficient amount of heat can be compensated in real time by a heating pattern selection process accompanying a change in the target control temperature.
[0018]
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the temperature higher than the standby temperature changed by the target control temperature changing unit is an image forming temperature.
[0019]
Therefore, the temperature higher than the standby temperature changed by the target control temperature changing means may be a considerably higher temperature, but by setting the image forming temperature, it is possible to start the image forming operation at the minimum necessary temperature. A sudden drop in the temperature of the fixing member caused by the rotation of the fixing member can be compensated in real time by a heating pattern selection process accompanying a change in the target control temperature.
[0020]
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the target control temperature changing unit changes the target control temperature prior to a state transition of the image forming apparatus from an image forming state to a standby state. The temperature is changed from the image forming temperature to a temperature lower than the image forming temperature.
[0021]
Immediately after the end of the image forming operation, the rotating fixing member is stopped, so that an overshoot of the heater temperature that may give stress and damage to peripheral components may occur. In particular, when the supplied commercial power supply voltage is higher than the rated applied voltage, this overshoot becomes even more remarkable. In general, even in regions where the commercial power supply voltage is 200V, 220V, 230V, 240V, and 100V, there are voltages such as 110V, 115V, and 120V. There is likely to be a difference. In consideration of such circumstances, prior to the state transition from the image forming state to the standby state, the setting contents of the table can be simply controlled by simply changing the target control temperature from the image forming temperature to a temperature lower than the image forming temperature. Without changing the fixing temperature, the fixing temperature can be reduced in real time in the cooling pattern selection process accompanying the change of the target control temperature prior to the standby state, and the overshoot amount can be suppressed.
[0022]
5. The image forming apparatus according to claim 4, further comprising a fixing device that heats and fixes the toner image on the transfer material using a fixing member having a plurality of fixing heaters having different light distributions. A temperature sensor provided in accordance with the light distribution for each time to detect a temperature around the fixing member, a drive control means for controlling an energization state to the fixing heater, and sampling an output of the temperature sensor at predetermined time intervals. Sampling means for acquiring temperature data around the fixing member, and a lighting heater determination table to be turned on among the plurality of fixing heaters based on the temperature data sampled by the sampling means and a target control temperature. Reference is made to at least two or more tables, and the control of the energization state by the drive control means according to the table setting contents. Determining means for determining a condition; and target control temperature changing means for changing the target control temperature from an image forming temperature to a temperature lower than the image forming temperature prior to a state transition of the image forming apparatus from an image forming state to a standby state. , Is provided.
[0023]
Therefore, the same effect as in the case of the invention described in claim 3 is exerted.
[0024]
According to a fifth aspect of the present invention, in the image forming apparatus according to the third or fourth aspect, the temperature lower than the image forming temperature changed by the target control temperature changing unit is a standby temperature.
[0025]
Therefore, the temperature lower than the image forming temperature changed by the target control temperature changing means may be considerably lower, but by setting the standby temperature, it is possible to directly shift to the control in the standby state.
[0026]
According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the fixing heater has a central light distribution having a high light distribution characteristic at an axial center of the fixing member. A light heater, and an end light distribution heater having high light distribution characteristics at both ends in the axial direction of the fixing member, wherein the temperature sensor corresponds to the central light distribution heater and the fixing member And a temperature sensor for detecting the temperature at the axial end of the fixing member in correspondence with the light distribution heater for the edge.
[0027]
Therefore, when a thin fixing heat roller is used to reduce the waiting time, the present invention can be suitably applied to the control of a fixing device as disclosed in Japanese Patent Application Laid-Open No. H11-157572 which can achieve a uniform temperature distribution.
[0028]
According to a seventh aspect of the invention, in the image forming apparatus according to the sixth aspect, at least two or more tables including the lighting heater determination table are provided for each of the central light distribution heater and the end light distribution heater. The central part control temperature, the end part control temperature, the central part temperature sensor, the central part present detection temperature at the time of the current sampling obtained by the end part temperature sensor, and the end part which are respectively set in advance according to the target control temperature. The lighting heater determination table, which is created using the parameter of the current detection temperature and determines the fixing heater to be turned on by the determination unit, includes a difference between the central control temperature and the central current detection temperature, and A fixing heater to be turned on is defined using the difference between the end control temperature and the end current detection temperature as a parameter.
[0029]
Therefore, since the fixing heater includes the central light distribution heater and the end light distribution heater, the table for determining the conditions for controlling the energized state takes into account the difference in the light distribution characteristics of these fixing heaters. By using the temperature information of the target control temperature and the temperature detected this time at the time of the current sampling, it is possible to provide excellent fixing temperature control. Further, since the fixing heater includes the central light distribution heater and the end light distribution heater, one of the conditions for controlling the energized state is to determine the fixing heater to be turned on. The difference between the target control temperature and the current detection temperature detected in the current sampling is specified as a parameter, and the fixing heater to be turned on is specified as the application table in consideration of the difference in the light distribution characteristics of these fixing heaters. Therefore, the fixing heater to be turned on can be simply and appropriately determined by referring to the lighting heater determination table, and the fixing temperature can be favorably controlled.
[0030]
According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the lighting heater determination table is configured such that the central portion light distribution heater is adapted to change the target control temperature at the time of transition from the standby state to the image forming state. And a pattern for simultaneously lighting the end light distribution heater.
[0031]
Therefore, at the time of the state transition from the standby state to the image forming state, the fixing member toward the start of the image forming operation is formed by the heating pattern in which the central light distribution heater and the end light distribution heater are simultaneously turned on with the change of the target control temperature. It is possible to reliably compensate in real time and insufficiency of a shortage of heat of the fixing member caused by the rotation of the fixing member.
[0032]
According to a ninth aspect of the present invention, in the image forming apparatus according to the seventh or eighth aspect, the lighting heater determination table is configured to change the target control temperature before the state transition from the image forming state to the standby state. The pattern includes a pattern for simultaneously turning off the light distribution heater and the end light distribution heater.
[0033]
Therefore, prior to the state transition from the image forming state to the standby state, the cooling pattern for simultaneously turning off the central light distribution heater and the end light distribution heater in accordance with the change of the target control temperature causes these heaters to precede the standby state. However, since a period in which the fixing member rotates in a state where all the lights are turned off occurs, the fixing temperature can be reduced reliably and in real time, and the overshoot amount can be suppressed.
[0034]
According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to ninth aspects, a table other than the lighting heater determination table determines a lighting interval of the fixing heater to be turned on by the determining unit. 6 is a table for determining an interval to be performed.
[0035]
Therefore, since the central light distribution heater and the end light distribution heater are provided as fixing heaters, one of the conditions for controlling the energized state is to determine the fixing heater to be turned on. The lighting interval (lighting duty) is determined in accordance with the above. By providing an interval determining table for this purpose, the lighting interval can be easily and appropriately set by referring to the interval determining table, and good fixing can be achieved. It can be used for temperature control.
[0036]
According to an eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect, the interval determination table for determining a lighting interval by the determination unit includes a difference between the central part control temperature and the central part current detected temperature; The lighting interval is defined using the difference between the end control temperature and the end current detection temperature as a parameter.
[0037]
Therefore, by using the interval determining table using the same parameters as the lighting heater determining table for determining the fixing heater to be turned on, the table can be easily created and the lighting interval can be easily and appropriately determined. Can be done.
[0038]
According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the first to eleventh aspects, at the time of warming up the fixing heater, the latest temperature data sampled by the sampling means before turning on the fixing heater is used. A warm-up processing mode changing unit configured to change a mode of the warm-up processing based on the warm-up processing mode.
[0039]
Therefore, although the temperature at the time of warming up the fixing heater is often around room temperature, in some cases, the temperature may be considerably lower than room temperature. In this case, a cold start is performed. In such a cold start state, in a fixing device having a small heat capacity and a plurality of fixing heaters having different light distributions, a temperature rise, a temperature distribution in an axial direction, a The time required for sufficient heating is long, and the normal warm-up time specified in catalog specifications or the like causes insufficient heating. Therefore, based on the latest temperature data sampled before the fixing heater is turned on, if the temperature is high, the warm-up process using the normal warm-up time specified in the catalog specification or the like is performed as quickly as possible. While the warm-up process is completed, if the temperature is low, the warm-up process monitors the actual sampling temperature without using the normal warm-up time specified in the catalog specification, etc. By adopting the mode of the warm-up process in consideration of the heat storage, the heating operation can be sufficiently performed and the fixing operation can be stabilized.
[0040]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. The image forming apparatus according to the present embodiment can be applied to a digital copying machine, a facsimile machine, a printer, and the like. As an example, an application example to a digital copying machine using an electrophotographic system is described. FIG. 1 is a front view showing a schematic configuration of a digital copier. In addition to having a printer engine 1 in a main body of the apparatus, a plurality of paper feed trays 2 and a manual feed tray 3 for providing transfer paper for printing by the printer engine 1 are provided. Further, an inner-type paper discharge stack unit 4 for discharging printed transfer paper is provided above the printer engine 1. Further, a reading unit (scanner unit) 5 for reading an image of a document to be copied and an operation panel 6 having a key unit for performing various operations by an operator and a display unit such as an LCD are provided at an upper portion of the apparatus main body. I have.
[0041]
Next, a schematic configuration example of the printer engine 1 will be described with reference to FIG. The printer engine 1 is of an electrophotographic type, and mainly includes a drum-shaped photoconductor 7. That is, a charging roller 8, an exposure unit 9 for laser light by an optical writing device, a developing unit 10, a transfer roller 11, and the like are provided in this order around the photoconductor 7 according to an electrophotographic process. A fixing device 12 is provided downstream of the transfer position of the transfer roller 11 in the transfer sheet transport direction.
[0042]
Here, a configuration example of the fixing device 12 will be described with reference to FIGS. The fixing device 12 according to the present embodiment has a configuration according to, for example, Patent Document 1 described above. In other words, the fixing roller 13 is basically a roller pair of a fixing roller 13 and a pressure roller 14 which are a fixing member with a built-in fixing heater. The fixing roller 13 is formed, for example, in a thin metal cylindrical shape whose surface is coated with a fluororesin. And is rotatably supported. The pressure roller 14 has a structure having a heat-resistant elastic body layer, is pressed against the fixing roller 13, and is supported so as to rotate following the fixing roller 13. Halogen heaters 15 and 16 as a plurality of fixing heaters are provided inside the fixing roller 13, and a PSU 19 is powered by the PSU 19 based on sensor outputs of thermistors 17 and 18 as temperature sensors which are brought into contact with the surface of the fixing roller 13. By appropriately driving the cutoff relay 20 and the triacs 21 and 22 for performing duty control, the lighting (light emission) of the halogen heaters 15 and 16 is turned on / off independently, and the surface temperature of the fixing roller 13 is kept constant ( (About 180 ° C).
[0043]
The two halogen heaters 15 and 16 have different light emission distributions. One of the halogen heaters 15 has a high light distribution at the axial center of the fixing roller 13 as shown in FIG. For small size with light emission distribution, it functions as a central light distribution heater. As shown in FIG. 4, the other halogen heater 16 is for a large size such as an A3 size having a light emission distribution such that the light distribution at the axial end of the fixing roller 13 is high. Functions as a light distribution heater.
[0044]
The arrangement of the thermistors 17 and 18 corresponds to the light distribution of the halogen heaters 15 and 16, and the thermistor 17 as the central temperature sensor matches the light distribution of the halogen heater (central light distribution heater) 15. The thermistor 18 serving as an end temperature sensor is arranged so as to detect the temperature of the outer peripheral surface near the center of the fixing roller 13 in the axial direction, and the fixing roller is adapted to the light distribution of the halogen heater 16 (end light distribution heater) 16. 13 are arranged so as to detect the temperature of the outer peripheral surface near the axial end.
[0045]
Next, an example of a schematic configuration of the entire electrical control system will be described with reference to a block diagram shown in FIG. First, a system control plate 33 for controlling a read control plate 31 for the reading unit 5 and a write control plate 32 for an optical writing unit for performing optical writing for forming a latent image on the operation panel 6 and the photoconductor 7 is provided. Is provided. As shown in FIG. 5, the system control board 33 includes a CPU 34 for centrally controlling each unit, a ROM 35 for fixedly storing programs and data, and a RAM 36 for rewritably storing various data and functioning as a work memory. In addition, a timer 37 and a rewritable / erasable EEPROM 38 are provided. A T sensor 40 for the developing unit 10, various image forming I / Os 41, a high voltage power supply (PSU) 19, and the like are connected to the system control board 33 via an I / O control board 39.
[0046]
Here, FIG. 6 shows a configuration example of a portion related to driving of the halogen heaters 15 and 16. That is, the high-voltage power supply (PSU) 19 functions as drive control means for the halogen heaters 15 and 16, and controls the energization state of the halogen heaters 15 and 16 by controlling the drive of the relay 20 and the triacs 21 and 22 described above. . Further, the sensor outputs of the thermistors 17 and 18 are converted into digital signals via the ADC portion of the I / O control plate 39, taken into the high voltage power supply (PSU) 19, and used for fixing heater control.
[0047]
In such a basic configuration, in the present embodiment, the conditions for controlling the energized state by the high voltage power supply (PSU) 19 include the halogen heater 15 or 16 to be turned on and the lighting interval (lighting duty) of the fixing heater. Two tables 51 and 52 having a look-up table structure for determination are provided in the EEPROM 38.
[0048]
That is, as a temperature control method for the halogen heaters 15 and 16 at the time of the image forming operation, a sampling means for sampling the heater temperature of the fixing roller 13 is provided as described later, and the sampling means is provided with a plurality of thermistors at predetermined intervals. Each temperature is sampled according to 17 and 18, and the sampled data signal: two data signals at the center and the end are used to calculate the temperature.
Determination of lighting duty (lookup table)
Determination of lighting heater (lookup table)
Is selected from the tables 51 and 52 respectively input. These two tables 51 and 52 can be replaced with a combination. The tables 51 and 52 may be replaced with tables having different configurations depending on the device state, state transition, or transfer paper size.
[0049]
Here, the tables used for determining the lighting heater or the lighting duty need not always be determined to be one. Of course, the lighting heater may be determined from a plurality of tables, but if the number of tables is large, a simple control configuration will not be obtained. Therefore, it is better to use as few tables as possible.
[0050]
In any case, the present embodiment is an example of application to a method of controlling the driving of the two halogen heaters 15 and 16, and is a table for determining a lighting heater that is not necessary for controlling only one fixing roller. Is also required, and as a result, at least two tables are required to be prepared.
[0051]
There are various parameters for determining the lighting duty or the fixing heater to be lit from the table. In the present embodiment, one of the purports is that no special detection means is added, and as a parameter that can be adopted for table creation, a method using the following element difference can be exemplified.
[0052]
element;
Central target control temperature on the central light distribution heater 15 side,
・ Temperature detected last time in the center at the previous sampling obtained by thermistor 17
・ Central current detection temperature at the time of current sampling obtained by thermistor 17
A target end control temperature on the end light distribution heater 16 side,
・ Temperature detected last time at the last sampling obtained by thermistor 18
・ Temperature detected this time at the end of the current sampling obtained by the thermistor 18
As a specific parameter example,
Parameter example:
(Central current detected temperature-Central previous detected temperature)
(Central control temperature-Central current detected temperature)
(Temperature detected at the end-Temperature detected last time at the end)
(End control temperature-End current detection temperature)
Can be mentioned.
[0053]
At this time, the table to be configured and the controllable items vary depending on what parameter is selected. However, as described above, since it is used for selection of any one of the two halogen heaters 15 and 16 having different light distribution characteristics and selection of the duty, the characteristics of the center / end portion are taken into consideration and the lighting is performed. At least two types of parameter elements are required in order to consider the fixing heater to be used and its lighting duty.
[0054]
Now, an example of the tables 51 and 52 will be described with reference to FIG. FIG. 7A shows an example of the interval determination table 52 for determining the lighting duty, and FIG. 7B shows an example of the lighting heater determination table 51 for determining the fixing heater to be turned on. In the example of the present embodiment, two parameters of (center control temperature−central present detection temperature) and (end control temperature−end present detection temperature) are used as parameters for determining conditions from these tables 51 and 52. The type is used for both tables 51 and 52.
[0055]
First, determination of a fixing heater to be turned on will be described with reference to a lighting heater determination table 51 of FIG. With respect to the target control temperature, High when the sampling temperature obtained by sampling is high, Low when the sampling temperature is low, and L when the difference from the target control temperature is greater than, for example, 10 ° C. The temperature state is grouped as M for 6 ° C., S for 6 ° C. to 3 ° C., zero (ZR) for less than 3 ° C., and a thermistor 17 (Th; center) for the center and an end for the end. Which of the halogen heaters 15 and 16 should be turned on according to the result of sampling with the thermistor 18 (Th; end). In the drawing, C and E indicate that two lamps are turned on, C indicates that the central light distribution heater 15 is turned on, E indicates that the end light distribution heater 16 is turned on, and 0 indicates that the two halogen heaters 15 and 16 are turned off.
[0056]
Even when the W number (heat amount) of the two halogen heaters 15 and 16 is different, or when there is a change in the light distribution characteristics, it can be handled only by changing the contents of the table 51.
[0057]
Next, the determination of the lighting duty of the fixing heater will be described with reference to the duty determination table 52 of FIG. In the present embodiment, the following five patterns are used as the on-duty for the halogen heater 15 or 16 to be turned on.
100: All lighting within sampling period
70: Performs soft start processing and lights for 70% of the sampling period
50: Perform soft start processing and turn on 50% of the time within the sampling cycle
30: Performs soft start processing and lights for 30% of the sampling period
0: the fixing heater is turned off within the sampling cycle
Is defined as being used.
[0058]
Here, if the result of searching the table 52 is other than 0%, the soft start is executed by the phase control of the triac 21 or 22, and when the phase control duty becomes 100%, the control duty determined in the table 52 is used. The halogen heater 15 or 16 is kept turned ON for a time corresponding to. For example, when the control cycle is 1 second and the control duty is 50%, the fixing heater is turned on for "0.5 seconds-soft start time" after the soft start ends, and is turned off for 0.5 seconds. For example, the time chart of FIG. 8 shows an example in which the control duty is changed every sampling cycle to 0%, 100%, 30%, 100%, 0%, 70%, and 30%.
[0059]
The soft start increases the phase control duty at each zero cross. The duty value is changed in the order of 30 → 40 → 50 → 100% (at start-up, 10 times each, 30 times). In the case of 50 Hz, the soft start is finished in 3 times × 10 msec = 30 msec (approximate: 30 times × 10 msec = 0.3 s at startup).
[0060]
An example of the fixing heater control executed by the CPU 34 during the image forming operation using such tables 51 and 52 will be described with reference to a schematic flowchart shown in FIG. In the present embodiment, attention is paid to a control example at the time of an image forming operation. When the image forming operation is started by a copy instruction or the like (Y in step S1), the control waits until the sampling timing is managed by the timer 37 (S2). ), When the sampling timing comes, a sampling operation to capture the sensor outputs of the thermistors 17 and 18 is performed (S3). The processing of steps S2 and S3 is executed as a function of the sampling means. The difference between each control temperature (central control temperature, end control temperature) and the current detection temperature obtained by sampling (central current detection temperature, end current detection temperature) is calculated (S4). Then, the tables 51 and 52 are searched using the obtained difference temperatures as parameters (S5), and the halogen heater 15 or 16 to be turned on and the lighting duty thereof are determined (S6). The processing of steps S4, S5, S6 is executed as a function of the determining means. When the halogen heater 15 or 16 to be turned on and the lighting duty are determined, the high-voltage power supply (PSU) 19 drives and controls the triac 21 or 22 in accordance with the determination, so that the energization state to the halogen heater 15 or 16 is determined. Is controlled (S7). The processing in step S7 is executed as a function of the drive control means. Thereafter, the same energization control process using the tables 51 and 52 is repeated for each sampling until the image forming operation is completed.
[0061]
Therefore, according to the present embodiment, basically, the toner image is heated and fixed on the transfer material by using the fixing roller 13 having a small heat capacity and incorporating the halogen heaters 15 and 16 having different light distributions. In the case of the fixing device 12, the state greatly varies depending on the environment due to the characteristics and the size, thickness, and type of the sheet to be passed, but at least two or more tables including the lighting heater determination table 51 to be turned on in advance. By preparing the tables 51 and 52 based on the results of the temperature sampling and referring to these tables 51 and 52 and determining the conditions for controlling the energized state by the high-voltage power supply (PSU) 19 based on the table settings, simple control can be performed. Thus, the fixing control can be stably performed. In particular, since the central light distribution heater 15 and the end light distribution heater 16 are provided as fixing heaters, the tables 51 and 52 for determining the conditions for controlling the energized state are provided by the halogen heaters 15 and 16. In consideration of the difference in optical characteristics, by using the temperature information such as the target control temperature, the previous detection temperature at the previous sampling, or the current detection temperature at the current sampling, it is provided for good fixing temperature control. Can be. Further, since the central light distribution heater 15 and the end light distribution heater 16 are provided as fixing heaters, one of the conditions for controlling the energized state is to determine the halogen heater 15 or 16 to be turned on. The lighting heater determination table 51 for this purpose considers the difference in light distribution characteristics of these halogen heaters 15 and 16 and calculates the difference between each target control temperature and the current detection temperature detected in the current sampling. Since the halogen heater 15 or 16 to be turned on is specified as a parameter, the halogen heater 15 or 16 to be turned on can be easily and appropriately determined by referring to the lighting heater determination table 51 to obtain a good fixing temperature. Can be used for control. In addition, since the fixing heater includes the central light distribution heater 15 and the end light distribution heater 16, one of the conditions for controlling the energized state is to determine the halogen heater 15 or 16 to be turned on. In addition to this, the lighting interval (lighting duty) is determined according to the temperature condition. By providing the spacing determination table 52 for this purpose, the lighting interval can be easily and easily referred to by referring to the spacing determination table 52. Appropriate settings can be made for good fixing temperature control. At this time, by using the interval determination table 52 using the same parameters as the lighting heater determination table 51 for determining the fixing heater to be turned on, the table can be easily created and the lighting interval can be determined. It can be done easily and properly.
[0062]
In any case, in a control system such as the fixing device 12 assumed in the present embodiment, the state of which fluctuates greatly depending on environmental fluctuations and the size, thickness, and type of paper to be passed, change of parts and specific conditions In many cases, it is necessary to reconsider the control conditions due to troubles in the system. Such a case can be dealt with by operating the set values in the tables 51 and 52. For example, for a machine having a fixing device characteristic in which the end temperature tends to rise, the upper right area of the tables 51 and 52 (the area selected when the end temperature is low and the center temperature is high). Countermeasures can be taken by lowering the numerical value. As a result, it becomes possible to reduce the number of cases such as specific conditions as much as possible. It is well known that the quality of control software is degraded by an increase in branching conditions (software complexity) such as case classification. It also improves quality.
[0063]
By the way, the above description is the processing control during the image forming operation, but the processing control in the case where there is a state transition before and after that will be described below.
[0064]
First, a description will be given of processing control at the time of power-on or at the time of a return operation (warm-up) from the energy saving state. Here, in the present embodiment, the fixing control temperature is
▲ 1 ▼ Reload temperature
(2) Standby temperature
(3) Image formation temperature
The following three are assumed. Here, the “reload temperature” takes into account the increase in the fixing temperature from the standby state to the image forming state so as not to impair the productivity of the image forming apparatus, and the image is formed at an earlier timing (lower fixing temperature). This is the temperature at which the formation operation (copy operation) can be started. “Standby temperature” is a temperature that is set lower than the image forming temperature to speed up the rise to the image forming temperature. The “image forming temperature” is a temperature set in consideration of the fixing property and the supply characteristics, and is a temperature to be maintained / controlled during the image forming operation. Normal,
Reload temperature <standby temperature <image forming temperature
Is set to
[0065]
Further, it is assumed that the room temperature is 20 ° C., and the warm-up time set in the catalog specification or the like is, for example, 9 seconds.
[0066]
The process control at the time of the return operation (warm-up) under such a condition will be described with reference to FIGS. First, during a return operation (warming up), after performing a series of initial settings such as initial hardware settings and device settings (S11), before driving the relay 20 and the triacs 21 and 22 (that is, before turning on the heater), the thermistor is set. The data of 17 and 18 are sampled (S12). The processing in step S12 is also executed as a function of the sampling means. Then, the latest thermistor data at this time obtained by sampling is converted into temperature data (S13), and it is determined whether the temperature is higher or lower than 20 ° C. corresponding to room temperature (S14). If the temperature data is equal to or higher than 20 ° C. (N in S14), the pattern A is selected as the warm-up processing pattern (S15). If the temperature data is lower than 20 ° C. (Y in S14), the warm-up processing is performed. Is selected as the pattern (S16). Here, the pattern A and the pattern B are different from each other in the mode of the warm-up process, and the processes in steps S14 to S16 are performed by a warm-up process mode changing unit that changes the mode of the warm-up process based on the latest temperature data. Performed as a function.
[0067]
Here, an example of the warm-up process in the case of the pattern A will be described with reference to FIG. First, the relay 20 is turned on (S21), and after 500 ms has elapsed (S22), the triacs 21 and 22 are both turned on to turn on the two halogen heaters 15 and 16 simultaneously (S23), and the temperature of the fixing roller 13 is increased. Let it. At the same time, a 9-second timer is started to measure a normal warm-up time of 9 seconds (S24). Thereafter, the sampling operation is continued (S25, S26), and whether the temperature data converted from the sampling data has reached the reload temperature (S27), or whether 9 seconds have elapsed (ie, the normal warm-up time of 9 seconds) (S28) is monitored, and the triacs 21 and 22 are temporarily turned off at the earlier timing of reaching the reload temperature (Y in S27) or elapse of 9 seconds (Y in S28) (S29). ), The image forming operation is enabled as a reload, and the display is made on the operation panel 6 or a buzzer is notified (S30). When the image forming operation is actually started at the end of the warm-up, the heater energization control using the tables 51 and 52 described above is performed. At this time, since the fixing roller 13 is driven to rotate in accordance with the start of the image forming operation, the temperature rise becomes gradual, but when the transfer paper reaches the fixing roller 13, it reaches the fixing control temperature level. A stable fixing operation is performed. If the image forming operation is not immediately executed at the end of the warm-up, the temperature control at the standby control temperature is continued.
[0068]
On the other hand, an example of the warm-up processing in the case of the pattern B will be described with reference to FIG. First, the relay 20 is turned on (S31), and after elapse of 500 ms (S32), both the triacs 21 and 22 are turned on to simultaneously turn on the two halogen heaters 15 and 16 (S33), and the temperature of the fixing roller 13 is increased. Let it. Thereafter, the sampling operation is continued (S34, S35), and it is monitored whether the temperature data converted from the sampling data has reached the reload temperature (S36). If the temperature data has reached the reload temperature (Y in S36), the triac 21 is temporarily stopped. , 22 are turned off (S37), the image forming operation is enabled as a reload, and the display is made on the operation panel 6 or a buzzer is notified (S38). When the image forming operation is actually started at the end of the warm-up, the heater energization control using the tables 51 and 52 described above is performed. At this time, since the fixing roller 13 is driven to rotate in accordance with the start of the image forming operation, the temperature rise becomes gradual, but when the transfer paper reaches the fixing roller 13, it reaches the fixing control temperature level. A stable fixing operation is performed. If the image forming operation is not immediately executed at the end of the warm-up, the temperature control at the standby control temperature is continued.
[0069]
Accordingly, an example of the temperature profile of the thermistors 17 and 18 in each case can be shown as in FIG. For example, FIG. 12A shows an example of the warm-up process in the case of the pattern A, in which the image forming operation is not immediately executed at the time of the warm-up reaching the reload temperature, and the temperature control at the standby temperature is continued. It shows the situation. FIG. 12B shows a state in which the image forming operation is executed immediately at the end of the warm-up when the reload temperature is reached in the warm-up processing example in the case of the pattern A. FIG. 12C shows an example of the warm-up processing in the case of the pattern A, in which the image forming operation is immediately executed at the end of the warm-up after the normal warm-up time of 9 seconds has elapsed although the reload temperature has not been reached. Is shown. On the other hand, FIG. 12D shows a state in which the image forming operation is executed immediately at the end of the warm-up when the reload temperature is reached in the warm-up processing example in the case of the pattern B.
[0070]
Therefore, according to the processing control at the time of such a return operation (warm-up), if the fixing temperature before the energization is started is about room temperature or more, the warm-up taking into account the normal warm-up time specified in the catalog specification or the like is considered. The warm-up operation is performed in the processing mode, and when the cold start is performed at a lower temperature than the room temperature, the monitoring is performed based on the monitoring of the actual sampling temperature without using the normal warm-up time defined in the catalog specification or the like. The mode of the warm-up process can be changed so that the warm-up operation is performed in the mode of the warm-up process.
[0071]
That is, the warm-up state of the halogen heaters 15 and 16 is often around room temperature. In some cases, however, the temperature may be considerably lower than room temperature. In this case, a cold start is performed. In such a cold start state, in the fixing device 12 according to the present embodiment including a plurality of halogen heaters 15 and 16 having a small heat capacity and different light distributions, the temperature rise and the axial temperature are reduced. The distribution and, furthermore, the time required for sufficient heating on the side of the pressure roller 14 is long, and the heating becomes insufficient during the normal warm-up time specified in the catalog specification or the like. Therefore, based on the latest temperature data sampled before the halogen heaters 15 and 16 are turned on, if the temperature is higher than room temperature, a warm-up time using a normal warm-up time specified in catalog specifications or the like is used. As a mode of the processing, the warm-up processing is completed in a short time as much as possible, and when the temperature is low such as below room temperature, the actual sampling temperature is not used without using the normal warm-up time specified in the catalog specification or the like. By setting the mode of the warm-up process to be monitored, that is, the warm-up process in consideration of sufficient heat storage in the fixing roller 13, the heating operation can be sufficiently performed and the fixing operation can be stabilized.
[0072]
Next, processing control associated with a state transition between the standby state and the image forming state will be described. Considering such a state transition, first, at the time of the state transition from the standby state to the image forming state, a sharp decrease in the temperature of the fixing roller 13 occurs due to the rotation operation of the fixing roller 13 toward the actual image forming operation. In this case, there is a possibility that a fixing failure may occur. Particularly, in the case of the fixing device 12 having a small heat capacity as in the present embodiment, there is a high possibility that a fixing failure occurs. Further, in the state transition from the image forming state to the standby state, the fixing roller 13 that has been rotating with the end of the image forming operation is stopped, so that an overshoot occurs in the roller temperature, causing stress and damage to peripheral components. Could give. In consideration of such points, in the present embodiment, the target control temperature to be controlled is changed at the time of or before the state transition, and the halogen heaters 15 and 16 are replaced with the halogen heaters 15 and 16 instead of the tables 51 and 52 described above. Tables 51a and 52a in a setting example as shown in FIG. 13 including patterns that are simultaneously turned on are used for state transition.
[0073]
Therefore, an example of operation control at the time of state transition will be described with reference to FIGS. The thick line in FIG. 12 shows how the target control temperature changes.
[0074]
For example, referring to the example of FIG. 12A, if the image forming operation start time t1 is not reached, the target control temperature is set to the standby temperature as a standby state, and the temperature profile detected by the thermistors 17 and 18 is the standby temperature. The temperature changes at a temperature close to the temperature or becomes slightly higher due to the occurrence of overshoot, but the temperature is lower than the image forming temperature. After that, based on a copy start instruction or the like, at the time of the state transition from the standby state at the image forming operation start time t1 to the image forming state, the target control temperature is the image forming temperature higher than the standby temperature (or the temperature higher than the image forming temperature). May be changed). This change of the target control temperature is executed as a function of the target control temperature changing means. Then, the rotation operation of the fixing roller 13 is also started from the image forming operation start time t1, and a temperature drop occurs. Here, with reference to the table 51a for state transition at the time t1 of the image forming operation accompanying the change setting of the target control temperature, the actual sampling temperature is considerably lower than the target control temperature, and the LowL * LowL portion Will be selected. That is, the condition that the halogen heaters 15 and 16 are simultaneously turned on and the duty is 100% is determined as the condition related to the control of the energized state. Conversely, when changing the state from the standby state to the image forming state, the tables 51a and 52a are used to change the target control temperature by providing a temperature difference of 10 ° C. or more between the standby temperature and the image forming temperature. Accordingly, it is set to include a pattern for simultaneously turning on the halogen heaters 15 and 16. Thus, when the state transitions from the standby state to the image forming state, it is possible to use a heating pattern that simultaneously turns on the halogen heaters 15 and 16 at a duty of 100% in accordance with the change of the target control temperature. A sudden temperature drop of the fixing roller 13 caused by the rotation of all the fixing rollers 13 = shortage of heat amount can be reliably compensated in real time. Thereafter, when the time has elapsed from the image forming operation start time t1 and the image forming operation is performed continuously or intermittently, the temperature of the entire fixing roller 13 is high (target control temperature = image forming temperature and When the control of the energization state is determined with reference to the tables 51a and 52a, the condition of LowL * LowL, that is, the simultaneous lighting of the halogen heaters 15 and 16 and the duty of 100% is the energization state. Is not determined as a condition relating to the control of. That is, in the correction control described in Patent Document 2 described above, the control may be in an excessively elevated state. However, according to the control of the present embodiment, it is possible to supply only necessary and sufficient heat. That is, in the present embodiment, the heat flow can be selected by simultaneous lighting or selective lighting of the plurality of halogen heaters 15 and 16, and the temperature is actually reduced by the fuzzy rule referring to the tables 51a and 521a. Since the heat flow is selected by simultaneous lighting or selective lighting of the plurality of halogen heaters 15 and 16 based on the prediction that a temperature drop is inevitably caused, rather than from the above, the image forming operation is executed at any duty. Even if there is no overcorrection processing (continuation of correction), the shortage of heat can be compensated in real time.
[0075]
Such a process of changing the target control temperature is the same in the cases shown in FIGS.
[0076]
On the other hand, a case of a state transition from the image forming state to the standby state will be described. In this case, before the end of the image forming operation, the final transfer sheet is detected (for example, a comparison between the number of jobs and the number of discharged sheets), and is indicated by a broken line in FIG. 12B or 12C, for example. As described above, the target control temperature is changed and set to a temperature lower than the image forming temperature (or a standby temperature) at time t2 (during the image forming operation) preceding time t3 when the image forming operation is actually finished. This change of the target control temperature is executed as a function of the target control temperature changing means. With such a change in the target control temperature, the actual sampling temperature is higher than the target control temperature, and when the tables 51a and 52a are referred to, the setting contents of the High and M portions are selected. That is, the condition for turning off the halogen heaters 15 and 16 at the same time is determined as a condition for controlling the energized state. Thus, the cooling pattern for simultaneously turning off the halogen heaters 15 and 16 at the time point t2 prior to the state transition from the image forming state to the standby state with the change of the target control temperature causes these cooling states to precede the standby state at the time point t3. Since the fixing roller 13 rotates while all the halogen heaters 15 and 16 are turned off, the fixing temperature can be reduced reliably and in real time, and the amount of overshoot can be suppressed.
[0077]
In addition, even when the image forming operation is forcibly interrupted halfway by a user's stop key operation or the like, the final transfer sheet is recognized according to the flag or the command, and the above-described state transition from the image forming state to the standby state is performed. Processing control is similarly performed.
[0078]
In FIG. 12, the sampling period is shortened to reduce the time lag before the reload temperature is reached (when the image forming operation cannot be started), but thereafter, the period is reduced to prevent flicker. It is longer.
[0079]
【The invention's effect】
According to the first aspect of the present invention, basically, there is provided a fixing device which heats and fixes a toner image on a transfer material by using a fixing member having a small heat capacity and a plurality of fixing heaters having different light distributions. In this case, the characteristics greatly vary depending on environmental fluctuations and the size, thickness, and type of paper to be passed, but at least two or more tables including a lighting heater determination table to be turned on are prepared in advance. By referring to these tables based on the temperature sampling result and the target control temperature, and determining the conditions for controlling the energization state by the drive control means based on the settings in the tables, stable fixing control can be performed with simple control. In addition to the above, even if the fixing device parts are changed or specifications are added, it is possible to easily and properly deal with it simply by changing the settings in the table. Kill. In addition, at the time of the state transition from the standby state to the image forming state, the image forming operation can be performed without changing the setting contents of the table by the simple control of changing the target control temperature from the standby temperature to a temperature higher than the standby temperature. A sudden decrease in the temperature of the fixing member caused by the rotation of the fixing member toward the start = insufficient amount of heat can be compensated in real time by a heating pattern selection process accompanying a change in the target control temperature.
[0080]
According to the second aspect of the present invention, in the image forming apparatus according to the first aspect, the temperature higher than the standby temperature changed by the target control temperature changing unit may be a considerably higher temperature, but is set to the image forming temperature. Therefore, at the minimum necessary temperature, a sudden temperature drop of the fixing member caused by the rotation of the fixing member toward the start of the image forming operation = a shortage of heat amount is determined in real time by a heating pattern selection process accompanying a change in the target control temperature. I can make up for it.
[0081]
According to the third and fourth aspects of the present invention, the target control temperature is changed from the image forming temperature to a temperature lower than the image forming temperature before the state transition from the image forming state to the standby state. The fixing temperature can be lowered in real time by the cooling pattern selection process accompanying the change of the target control temperature prior to the standby state without changing the setting contents of the above, and the overshoot amount can be suppressed.
[0082]
According to the fifth aspect of the present invention, in the image forming apparatus according to the third or fourth aspect, the temperature lower than the image forming temperature changed by the target control temperature changing unit may be a considerably lower temperature, but the standby temperature By doing so, it is possible to directly shift to the control in the standby state.
[0083]
According to the invention described in claim 6, in the image forming apparatus according to any one of claims 1 to 5, the temperature distribution can be made uniform when a thin fixing heat roller is used to reduce the waiting time. 1 can be suitably applied to the control of the fixing device.
[0084]
According to the seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, since the central light distribution heater and the end light distribution heater are provided as the fixing heaters, it is possible to determine the conditions for controlling the energized state. In consideration of the difference in light distribution characteristics of these fixing heaters, a table is created using temperature information such as target control temperatures and temperature detected this time at the time of current sampling, thereby achieving good fixing temperature control. Can be offered. Further, since the fixing heater includes the central light distribution heater and the end light distribution heater, one of the conditions for controlling the energized state is to determine the fixing heater to be turned on. The difference between the target control temperature and the current detection temperature detected in the current sampling is specified as a parameter, and the fixing heater to be turned on is specified as the application table in consideration of the difference in the light distribution characteristics of these fixing heaters. Therefore, the fixing heater to be turned on can be simply and appropriately determined by referring to the lighting heater determination table, and the fixing temperature can be favorably controlled.
[0085]
According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, at the time of a state transition from the standby state to the image forming state, the central light distribution heater and the end light distribution heater are changed according to the change of the target control temperature. Is turned on at the same time, a sudden temperature drop of the fixing member, which is caused by the rotation of the fixing member toward the start of the image forming operation, that is, a shortage of heat can be reliably compensated in real time.
[0086]
According to the ninth aspect of the present invention, in the image forming apparatus according to the seventh or eighth aspect, the central light distribution heater and the end portion light distribution are accompanied by a change in the target control temperature prior to the state transition from the image forming state to the standby state. The cooling pattern that turns off the optical heater at the same time causes a period in which the fixing member rotates with all of the heaters turned off prior to the standby state, so that the fixing temperature can be reduced reliably and in real time, and overshoot can be achieved. The amount can be suppressed.
[0087]
According to the tenth aspect of the invention, in the image forming apparatus according to any one of the first to ninth aspects, since the central portion light distribution heater and the end portion light distribution heater are provided as the fixing heater, the control of the energization state is performed. One of the conditions is to determine the fixing heater to be turned on. In addition to this, there is a determination of the lighting interval (lighting duty) according to the temperature condition, and an interval determination table for this is provided. The lighting interval can also be easily and appropriately set by referring to the interval determination table, and can be used for excellent fixing temperature control.
[0088]
According to the eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect, the interval determining table using the same parameters as the lighting heater determining table for determining the fixing heater to be turned on is used. In addition, the table can be easily created, and the lighting interval can be easily and appropriately determined.
[0089]
According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the first to eleventh aspects, based on the latest temperature data sampled before the fixing heater is turned on, if the temperature is high, a catalog is generated. As a mode of the warm-up process using the normal warm-up time specified in the specifications, etc., the warm-up process is completed in a short time as much as possible. By using a warm-up process that monitors the actual sampling temperature without using the up time, that is, a mode of a warm-up process that takes into consideration sufficient heat storage in the fixing member, sufficient heating is performed to stabilize the fixing operation. Can be.
[Brief description of the drawings]
FIG. 1 is a front view showing a schematic configuration of a digital copying machine according to an embodiment of the present invention.
FIG. 2 is a front view showing a schematic configuration example of a printer engine part.
FIG. 3 is a schematic vertical sectional side view showing a configuration example around a fixing device.
FIG. 4 is a characteristic diagram showing a light distribution of the fixing heater.
FIG. 5 is a block diagram illustrating a schematic configuration example of an entire electrical control system.
FIG. 6 is a block diagram illustrating a schematic configuration example of a portion related to driving of the fixing heater.
FIG. 7 is an explanatory diagram showing a basic setting example of table contents.
FIG. 8 is a time chart illustrating an example of variable lighting duty.
FIG. 9 is a schematic flowchart illustrating a fixing heater control example.
FIG. 10 is a schematic flowchart illustrating an example of a process control during warm-up.
FIG. 11 is a schematic flowchart showing an example of warm-up processing patterns A and B.
FIG. 12 is an explanatory diagram showing a temperature profile and the like of a thermistor.
FIG. 13 is an explanatory diagram showing an example of setting table contents.
[Explanation of symbols]
12 Fixing device
13 Fixing member
15 Central light distribution heater, fixing heater
16 Edge light distribution heater, fixing heater
17 Central temperature sensor, temperature sensor
18 Edge temperature sensor, temperature sensor
19 Drive control means
51a Lighting heater determination table, table
52b Interval determination table

Claims (12)

An image forming apparatus including a fixing device that heats and fixes a toner image on a transfer material using a fixing member having a plurality of fixing heaters having different light distributions,
A temperature sensor provided for each fixing heater in accordance with the light distribution and detecting a temperature around the fixing member;
A drive control unit for controlling an energization state to the fixing heater,
Sampling means for sampling the temperature sensor output every predetermined time to obtain temperature data around the fixing member;
Based on the temperature data sampled by the sampling means and the target control temperature, at least two or more tables including a lighting heater determination table to be turned on among the plurality of fixing heaters are referred to, and the table setting contents are used. Deciding means for deciding a condition relating to control of the energized state by the drive control means,
Target control temperature changing means for changing the target control temperature from a standby temperature to a temperature higher than the standby temperature when the image forming apparatus transitions from a standby state to an image forming state,
An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the temperature higher than the standby temperature changed by the target control temperature changing unit is an image forming temperature. The target control temperature changing means changes the target control temperature from an image forming temperature to a temperature lower than the image forming temperature prior to a state transition of the image forming apparatus from an image forming state to a standby state. Item 3. The image forming apparatus according to Item 1 or 2. An image forming apparatus including a fixing device that heats and fixes a toner image on a transfer material using a fixing member having a plurality of fixing heaters having different light distributions,
A temperature sensor provided for each fixing heater in accordance with the light distribution and detecting a temperature around the fixing member;
A drive control unit for controlling an energization state to the fixing heater,
Sampling means for sampling the temperature sensor output every predetermined time to obtain temperature data around the fixing member;
Based on the temperature data sampled by the sampling means and the target control temperature, at least two or more tables including a lighting heater determination table to be turned on among the plurality of fixing heaters are referred to, and the table setting contents are used. Deciding means for deciding a condition relating to control of the energized state by the drive control means,
Target control temperature changing means for changing the target control temperature from the image forming temperature to a temperature lower than the image forming temperature prior to a state transition of the image forming apparatus from the image forming state to the standby state;
An image forming apparatus comprising: The image forming apparatus according to claim 3, wherein the temperature lower than the image forming temperature changed by the target control temperature changing unit is a standby temperature. The fixing heater includes a central light distribution heater having a high light distribution characteristic at a central portion in the axial direction of the fixing member, and an end portion having high light distribution characteristics at both axial ends of the fixing member. A light distribution heater,
The temperature sensor includes a central temperature sensor that detects a temperature of an axial center of the fixing member corresponding to the central light distribution heater, and a shaft of the fixing member corresponding to the end light distribution heater. An end temperature sensor for detecting the temperature of the center end.
The image forming apparatus according to claim 1, wherein: At least two or more tables including the lighting heater determination table include a central control temperature which is a preset target according to the target control temperature for each of the central light distribution heater and the end light distribution heater. , The end control temperature, the center temperature sensor, the center current detection temperature at the time of the current sampling obtained by the end temperature sensor, created using the parameters of the end current detection temperature,
The lighting heater determination table for determining the fixing heater to be turned on by the determining means includes a difference between the central part control temperature and the central part current detection temperature, and the end part control temperature and the end part current detection temperature. The fixing heater to be turned on as a parameter with the difference from
The image forming apparatus according to claim 6, wherein: The lighting heater determination table includes a pattern for simultaneously turning on the central light distribution heater and the end light distribution heater with a change in target control temperature during a state transition from a standby state to an image forming state,
The image forming apparatus according to claim 7, wherein: The lighting heater determination table includes a pattern for simultaneously turning off the central light distribution heater and the end light distribution heater with a change in target control temperature prior to a state transition from an image forming state to a standby state,
9. The image forming apparatus according to claim 7, wherein: The tables other than the lighting heater determination table are interval determination tables for determining the lighting interval of the fixing heater to be turned on by the determining unit.
The image forming apparatus according to claim 1, wherein: The interval determination table for determining the lighting interval by the determination means, the difference between the central control temperature and the central current detection temperature, and the difference between the end control temperature and the end current detection temperature. Defines the lighting interval as a parameter,
The image forming apparatus according to claim 10, wherein: 12. A warm-up processing mode changing unit for changing a mode of the warm-up process based on the latest temperature data sampled by the sampling unit before turning on the fixing heater when the fixing heater is warmed up. An image forming apparatus according to any one of the preceding claims.

Images