JP2002214960A - Image forming device - Google Patents

Abstract

(57) [Problem] To provide an image forming apparatus in which the peak value of power consumption by a heater is reduced and the capacity of a power supply device is increased. SOLUTION: A fixing device 39 of an image forming apparatus 1 is provided with heating / pressurizing rollers 39a and 39b heated by roller heaters 39c and 39d, respectively, and an oil supply unit 40 heated by an oil heater 40b. Each heater is driven by a heater control unit 45. At the time of steady operation (operation) of the image forming apparatus, when the roller heater 39c is driven, the control unit 71 integrally controls the heater control unit 45 so as to stop driving the oil heater 40b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for developing a latent image formed on a photoreceptor by an electrophotographic method using a developing agent, transferring the latent image on a transfer material, and further heating and pressurizing with a fixing device to form an image. In particular, the present invention relates to an image forming apparatus capable of reducing a peak of heater power consumption in a fixing device and preventing an increase in the capacity of a power supply device.

[0002]

2. Description of the Related Art Generally, electrophotographic image forming apparatuses include an electrophotographic copying machine, an electrophotographic printer (such as an LED printer and a laser beam printer), an electrophotographic facsimile machine, and an electrophotographic word processor.
These image forming apparatuses develop a latent image formed on a photosensitive drum as a photosensitive member with a developer (hereinafter, referred to as toner), transfer the toner image onto a transfer material such as plain paper,
Further, the image is formed by fixing with a heating and pressing roller in a fixing device. At that time, the toner is heated and melted by the fixing device.
There is a problem that an adhesive action acts between the heating and pressing roller and the image forming surface of the transfer material, so that the transfer material adheres to the heating and pressing roller hardly to be peeled off and a winding phenomenon occurs. Therefore, a method of supplying oil such as silicon oil to the heating and pressing roller is usually adopted. The oil is quantitatively supplied to the heating and pressing roller from an oil supply unit provided in the fixing device or in a device adjacent thereto, and is applied to the surface thereof.

[0003] However, since the viscosity of oil has a temperature dependency, when the temperature changes, the supply amount (application amount) to the heating and pressing roller varies, and the gloss of the formed image becomes uneven. There is. In order to solve the problem, attempts have been made to adjust the oil to a specified temperature with a heater, maintain the viscosity constant, and stabilize the application amount. However, in general, a heater consumes a large amount of power. When a roller heater and an oil heater for heating a heating / pressing roller are provided side by side, a large power consumption peak occurs when both are driven simultaneously. Needs to be large enough to accommodate it.

FIG. 6 is a time lapse diagram of the conventional heating control of the roller heater and the oil heater. The horizontal axis is time t
In (s), the vertical axis (a) shows the temperature change of the heating and pressing roller,
(B) is a change in power consumption of the roller heater, (c) is a change in oil temperature, (d) is a change in power consumption of the oil heater, and (e) is a change in total power consumption of (b) and (d). It is.

First, when the image forming apparatus is started (at the time of heat-up), the temperature of the heating / pressing roller is lower than its specified value (set value) Tus as shown in FIGS.
The oil temperature is also lower than the specified value (set value) Tos.
Therefore, at the time of heat-up, both the roller heater and the oil heater are driven (ON state) as shown in (b) and (d), and the power consumption becomes a large peak power value Wp as shown in (e).

After the temperature of the heating / pressing roller or the temperature of the oil reaches the specified value, the control is shifted to the operation control,
Each heater is driven / not driven (ON-OFF) so as to maintain a specified value. However, since the two heaters are controlled independently of each other, when both heaters are driven at the same time, the peak power Wp having the same magnitude as that at the time of heating up is consumed, as shown in FIGS. Generally, at the time of heat-up, the component devices for image formation hardly consume power, so even if a large peak power Wp is consumed by the heater, power consumption in the image forming apparatus does not increase. However, during operation, the power consumption of the heater and the other components is added up, so that the capacity of the power supply must be designed to be large correspondingly.

[0007]

When the size of the power supply is increased in accordance with the power consumption of the heater, the size and weight of the image forming apparatus are increased. Therefore, an object of the present invention is to solve the problem of excessive power consumption due to such a heater.

[0008]

A typical configuration according to the present invention for solving the above-mentioned problems is to develop a latent image formed on a photoreceptor by an electrophotographic method with a developer, and to develop the latent image on a transfer material. In an image forming apparatus for forming an image by transferring and further heating and pressurizing the image with a fixing device, the fixing device includes a heating and pressing roller, and a roller temperature adjusting unit for adjusting a heating temperature of the heating and pressing roller to a specified temperature. A roller heater driven by the roller temperature adjusting means, an oil supply unit for supplying oil to the heating / pressurizing roller, an oil temperature adjusting means for adjusting the temperature of the oil to a specified temperature, and driven by the oil temperature adjusting means. Oil heater that is
While the roller heater is being driven, control means for controlling the oil temperature adjusting means is provided so as not to drive the oil heater.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of the configuration of the image forming apparatus of the present invention. This image forming apparatus is a digital image forming apparatus, and includes a reader unit 1 in an upper part of the apparatus main body and a printer unit 2 in a lower part.

[Reader Unit] The reader unit 1 includes a document table 11 on which a document is placed, a document pressure plate 12 for pressing the placed document from above, a light source 13 for irradiating the image surface of the document, The main components are a plurality of mirrors 14 and lenses 15 that guide the reflected light, a CCD that photoelectrically converts the reflected light, and an image processing unit 16 that performs various types of image processing on electrical signals obtained by the CCD. And this image processing unit 16
Has image processing functions such as A / D conversion, S / H, shading correction, masking correction, scaling, and LOG conversion.

[Printer Unit] The printer unit 2 includes an image control unit 17 that converts an electric signal output from the image processing unit 16 of the reader unit 1 into a laser drive signal, and a laser element 1.
8, a polygon scanner 19, an image forming unit, a transfer material transporting unit, and a fixing unit 39 as main components.

[Image Forming Section] The image forming section has a photosensitive drum 30 as a photosensitive member rotatably supported by the apparatus main body, and is driven to rotate clockwise (in the direction of the arrow) by driving means (not shown). A primary charger 31 for uniformly charging the surface of the photosensitive drum 30 along the periphery of the photosensitive drum 30 and in the direction of rotation thereof, a developing device 20 as a developing unit for developing an electrostatic latent image on the photosensitive drum 30, A transfer charger 35 as a transfer unit for transferring the toner image on the drum 30 to the transfer material P, a cleaner 34 for removing transfer residual toner on the photosensitive drum 30, an auxiliary charger 33 for removing static electricity, and pre-exposure for removing residual charges. A lamp 32 is provided. The developing device 20 is provided with a developing roller 20a, and the developing roller 20a rotates in a direction opposite to the photosensitive drum 30 to develop a toner image on the photosensitive drum 30. The cleaner 34 is provided with a cleaner blade 34a,
The cleaner blade 34a scrapes off the toner on the photosensitive drum 30 and is collected in the toner container of the developing device 20.

[Transfer Material Transport Unit] The transfer material transport unit transports the transfer material to the image forming unit. In this embodiment, two types of transfer materials P having different dimensions are selected and supplied to the transfer charger 5. It has become. The transfer material P in one paper cassette 36 is supplied from the tray 36 to the transfer charger 5 via a paper feed device such as a paper feed roller 36a and a transport roller 36b.
The sheet is supplied to the transfer charger 5 via a sheet feeding device such as a conveying roller 37b (and 36b).

The transfer material transport section has a multi-sheet feeder 43 in addition to the above-mentioned sheet feeder. By using the multi-sheet feeding device 43, sheets having different properties such as material and size can be directly supplied to the transfer charger 35 from the outside of the device.

[Fixing Device] The fixing device 39 has a pair of heating and pressing rollers 39 a and 39 b and an oil supply section 40. The transfer material P from the image forming unit is transferred to the pre-fixing belt 3
8, the heating / pressing rollers 39a, 39b of the fixing device 39
The transfer material P, which has been supplied during the fixing, is discharged from the post-fixing belt 42 to the sheet discharge tray 41.

Next, the operation of the image forming apparatus will be described. First, a document is placed on a document table 11 with its image side down, and the document is pressed by a document pressure plate 12 from above. Upon activation, the light source 13 moves in the direction of the arrow K1 while irradiating light, scans the image surface of the original, and the reflected light image from the image surface is transmitted to the CCD of the image processing unit 16 via the plurality of mirrors 14 and lenses 15. And is converted into an electric signal as image information. After various image processing is performed in the image processing unit constituting the image processing unit 16, the electric signal is output to the next printer unit 2.

In the printer section 2, the image control section 17 receiving the electric signal drives the laser element 18. The laser beam is reflected by the polygon scanner 19 rotating at high speed, is uniformly charged by the primary charger 31, and scans (irradiates) the photosensitive drum 30 rotating clockwise at a constant speed.
The electrostatic latent image formed thereby is developed by the toner in the developing device 20 and further transferred to the transfer material P conveyed by the action of the charge applied to the transfer charger 35.

The transfer material P is then conveyed by a pre-fixing belt 38 to a fixing device 39, where a heating and pressing roller 39a,
The toner image is fixed by being heated and pressurized while passing through the sheet 39b, and the transfer material P after fixing is discharged to the sheet discharge tray 41 via the belt 42 after fixing. On the other hand, the photosensitive drum 3 after the transfer
In the case of 0, the transfer residual toner is removed by the cleaner 34, the charge is removed by the auxiliary charger 33, and the remaining charge is removed by the exposure lamp 32, and the primary charger 31 uniformly charges again.

FIG. 2 is a block diagram showing a control system of the image processing section 16 and the fixing device 39 in the apparatus shown in FIG. 1. FIG. 3 is a block diagram showing a control system of the entire image processing apparatus. .

First, in FIG. 2, the fixing device 39 includes a heating / pressurizing roller 39a disposed on the image forming side (upper side in the drawing) of the transfer material P passing therethrough, and an image forming side of the transfer material P opposed thereto. It has a heating / pressing roller 39b arranged on the opposite side (lower side in the drawing), and roller heaters 39c and 39d such as halogen heaters are provided inside each of them. Further, temperature measuring devices 39e and 39f such as thermistor sensors for measuring the temperatures of the roller heaters 39c and 39d are provided.

An appropriate amount of oil supplied from the oil supply unit 40 is always applied to the heating and pressing roller 39a disposed on the image forming side of the passing transfer material P. Oil supply unit 4
0 denotes an oil tank 40a, an oil heater 40b, a temperature transmitter 40c for transmitting oil temperature, and the temperature transmitter 40c.
Temperature measuring device 40 such as a thermistor sensor provided in contact with c
d, two application rollers 40e that are in contact with each other are provided, and oil is applied to the heating and pressing roller 39a via the application rollers 40e.

[Temperature Adjusting Means] Each temperature measuring device 39e, 3
9f and 40d are input to the heater control unit 45, and are compared with respective predetermined temperatures set in the comparison unit, and the respective heaters are turned on and off so that they match.
FF control (drive-non-drive control) is performed. Heater control unit 4
Reference numeral 5 controls a power supplied from a power supply device 44 incorporated in the image forming apparatus 1 by a triac or the like, and outputs a drive signal to the heater. The (common) heater control unit 45 and the temperature measuring device 39e use one roller temperature adjusting means, the heater control unit 45 and the temperature measuring device 39f use the other roller temperature adjusting device, and the heater control unit 45 and the temperature measuring device 40d. Constitute oil temperature adjusting means.

[Control Means] A control means 71 constituted by a computer device, a sequencer and the like integrally controls the entire image forming apparatus, and as a part thereof, the image processing section 16 and an image input section 72 constituting the same. , The image controller 17, the heater controller 45, and the like. The measurement signals from the temperature measuring devices 39e, 39f, and 40d are input to the heater control unit 45 constituting each temperature adjusting unit and sent to the control unit 71 as described above. The control means 71 constantly monitors these signals by a resistance measuring circuit,
When an abnormal state such as dropout or disconnection of the temperature measuring devices 39e, 39f, and 40d occurs, the abnormal state is detected by the operation unit
2 (FIG. 3).

Next, the configuration of the control means 71 will be described with reference to the block diagram of FIG. The control unit 71 includes an A / D converter 103 for converting analog signals from the image processing unit 16, the image control unit 17, the operation unit 102, and the temperature measuring devices 39e, 39f, and 40d into digital signals.
A high-voltage control unit 105 for controlling the voltage of a high-voltage unit in various chargers, various motor control units 107, a DC load control unit 108, a sensor signal processing unit 109, a heater control unit 45, and the like are connected.

The control means 71 includes a CPU (central processing unit) 7
1a, ROM (read only memory) 71b, RAM
The CPU 71a includes a (random access memory) 71c, a timer unit 71d, and the like, and executes a predetermined image forming sequence and the like by a program stored in the ROM 71b. At this time, the RAM 71c stores rewritable data that needs to be temporarily or permanently stored. Such data includes a high voltage set value for the high voltage control unit 105, image forming command information from the operation unit 102, and various other data.

Next, the operation of the control means 71 will be described. First, the image processing unit 16 performs A / D conversion of an image signal from the CCD,
S / H, shading correction, masking correction, scaling,
Image processing such as LOG conversion is performed, and the control unit 71 sets specifications, data, and the like of each unit necessary for the image processing. The image control unit 17 regulates the image size and optimally PWM-controls the laser element 18 based on the digital video data output from the image processing unit 16.
The control unit 71 performs settings necessary for PWM control of the laser element 18. The operation unit 102 allows the user to set the number of copies, the copy magnification, the density, and the like, and also displays whether or not an image is being formed, the progress of the number of copies, jam occurrence information, and the like. I do.

In order to transport the transfer material P and drive each unit, the image forming apparatus is provided with a DC load such as a motor, a clutch / solenoid, etc. in various places, and a photo interrupter, a micro switch, etc. for monitoring the operation thereof. Sensors are arranged. The control means 71 performs drive control of each component of the apparatus and information collection and analysis of sensors. That is, based on a signal from the sensor signal processing unit 109, a control signal is output to the motor control unit 107 to control these motors, and a control signal is output to the DC load control unit 108 to control the clutch / solenoid. . Further control means 7
1 outputs a control signal to the high voltage control unit 105, whereby the primary charger 31, the auxiliary charger 33, the transfer charger 35,
An appropriately controlled high voltage is supplied to the developing roller 20a and the like.

Further, the control means 71 includes the fixing device 39
The measurement signals from the temperature measuring devices 39e, 39f, 40d provided in the A / D converter 103 are converted into digital values by the A / D converter 103 and inputted, and the signals of the driving states of the roller heaters 39c, 39d and the oil heater 40b are provided. Is entered.
Then, the control means 71 integrally controls the heaters based on these pieces of information by a method described later.

FIG. 4 shows the time lapse of the heating control by the control means 71 in accordance with FIG.
In (s), each vertical axis shows (a) a change in temperature of the heating / pressing roller 39a, (b) a change in power consumption of the roller heater 39c, (c) a change in oil temperature, and (d) a change in oil temperature. (E) is a change in the total power consumption of (b) and (d).

Next, an integrated control of the roller heater 39 and the oil heater 40b by the control means 71 will be described with reference to FIG. This example shows the side where oil is applied,
That is, a roller heater 39c for heating the heating and pressing roller 39a disposed on the image forming side of the passing transfer material P
And the oil heater 40b are integrally controlled by the control means 71. The other roller heater 3
9d is adjusted to a specified temperature by roller temperature adjusting means independently of the control.

The temperature of the heating / pressurizing roller 39a is set to the specified value Tus similar to FIG. 6, but the temperature of the oil is set in two steps, ie, the specified value Tos similar to FIG. Set to stage. Tos is the oil temperature control point at the time of heat-up (the point at which the oil heater 40b is turned off when the temperature rises above), and Tol is the oil temperature control point at the time of operation. The reason for setting the high specified value Tol during operation as described above is that, as described above, the operation of the roller heater 39c is prioritized during the operation of the image forming apparatus, and the oil heater is only activated when it is not driven (OFF). 40b drive (O
This is to reduce the peak power by making N), so that the oil temperature does not drop significantly even if the OFF period of the oil heater 40b becomes somewhat longer.

At the time of heat-up, as in the case of FIG. 6, the temperature of the heating / pressing roller 39a is set to a specified value (set value) Tu.
s, the oil temperature is also its specified value (set value) To
s, the roller heater 39c and the oil heater 40b are both driven (ON) as shown in (b) and (d), and a large peak power Wp as shown in (e) is consumed. The temperature of the heating / pressurizing roller 39a is set to a specified value Tu.
s, the roller heater 30c shifts to ON-OFF control, and after the oil temperature reaches the specified value Tos, the oil heater 40b shifts to ON-OFF control, thereby completing the heat-up. It will be in the operating state. During operation, the oil heater 40b is ON / OFF controlled so as to maintain the oil temperature at Tol. However, when the roller heater 39c is driven (ON), the oil heater 40b is not driven.

Next, the implementation of the heater control algorithm shown in FIG. 4 will be specifically described with reference to the flowchart of FIG. 5 are all programmed in the control means 71 in advance. In FIG. 5, for simplicity, the upper heater is the upper roll heater 39 shown in FIG.
c, the lower heater similarly represents the lower roll heater 39d, the oil represents oil, and the oil heater represents the oil heater 40b.

First, when the temperature control is started (S10)
1), upper heater heat-up end flag (IFSU),
The lower heater heat-up end flag (IFSL) and the heat-up end flag (IFS) are all reset (S1).
02). Subsequently, the temperature TL of the lower heating / pressing roller 39b
Is measured (S103), and it is determined whether or not TL is lower than a specified temperature (TSL) of the heating / pressing roller 39b (S10).
4) When the temperature is low, the lower heater is turned on (S105), and when the temperature is high, the lower heater is turned off, and at the same time, the lower heater heat-up indicating that the heat-up to the lower heating and pressing roller 39b is completed. The flag (IFSL) is set (S106).

Subsequently, the upper heating / pressing roller 39a
Is measured (S107). If the temperature TU is lower, it is determined whether the temperature is lower than a prescribed temperature (TUS) of the heating / pressing roller 39a (S108). If lower, the upper heater is turned on (S108).
109), when it is high, the upper heater is turned off, and at the same time, the upper heater heat-up end flag (IF
SU) is set (S110).

Next, the oil temperature TO is measured (s11).
1) It is determined whether or not TO is lower than a prescribed value (TOS) of the temperature of the oil heater (S112). If it is lower, the oil heater is turned on (S113). It is determined whether or not both the IFSU) and the lower heat-up end flag (IFSL) are set (S114). If set
That is, when the heat-up of both the upper heater and the lower heater has been completed and the heat-up of the oil heater has been completed, an indication that image formation is possible is displayed on the operation unit 102, and the image formation sequence is executed. A heat-up end flag (IFS) is set to enable reception, and the application controlled by the control unit 71 is permitted to receive image formation (S115).

On the other hand, after the oil heater is turned on in S113, an abnormality occurs in the heater control unit 45 (FIG. 2) or other parts, and when the abnormality is detected by the control unit 71 (S120), After forcibly turning off the upper heater, the lower heater, and the oil heater (S121), the temperature control is forcibly terminated (S122). If no abnormality is detected, the process returns to S103, and the above-described temperature adjustment sequence of each heater is repeated.

When the image can be formed in S115, a sequence for suppressing the peak of the power consumption at the time of image formation (during operation) is executed thereafter. That is, first, it is determined whether or not the upper heater is ON (S11).
6) If the upper heater is on, the oil heater is forcibly turned off (S117) (change point c). If the upper heater is not ON, it is determined whether the temperature of the oil heater is lower than a second specified temperature Tol (S
118), if lower than Tol, turn on oil heater
(S119) (change points d to e). If it is higher than Tol, proceed to S120 without turning on the oil heater,
As described above, the temperature adjustment sequence of each heater is repeated after the abnormality is detected.

As described above, the temperature of the oil heater 40b (oil heater) is adjusted by the first (Tos) and second (Tos).
By controlling with the two specified values of l), simultaneous driving of the upper roller heater 39c (upper heater) and the oil heater 40b can be avoided as shown in the operation in FIG. Thus, the power consumption peak can be significantly reduced without causing a large error in the temperature adjustment of the heating and pressing roller 39a and the oil.

[Other Embodiments] In the above embodiment, the simultaneous driving of the upper roller heater 39c and the oil heater 40b is avoided, but the lower roller heater 39d and the oil heater The simultaneous driving with the heater 40b may be avoided. In this case, the upper roller heater 39c is independently adjusted to the specified temperature by the heater temperature adjusting means.

[0041]

As described above, according to the present invention, during operation of the image forming apparatus, while the roller heater is being driven, the oil heater is not driven while the roller heater is being driven. Therefore, it is possible to avoid an increase in the peak value of the power consumption due to the overlap of the driving of the heaters, thereby solving the problems such as an increase in the capacity of the power supply device and an increase in the size and weight of the image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a configuration of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram illustrating a control system of an image processing unit and a fixing device.

FIG. 3 is a block diagram illustrating a control system of the entire image processing apparatus.

FIG. 4 is a diagram for explaining a lapse of time of heating control of each heater according to the present invention.

FIG. 5 is a diagram showing a flowchart of heater control according to the present invention.

FIG. 6 is a diagram for explaining a lapse of time of heating control of each heater according to a conventional method.

[Explanation of Signs] 1 Reader unit 2 Printer unit 11 Document table 12 Document pressure plate 13 Light source 14 Mirror 15 Lens 16 Image processing unit 17 Image control unit 18 Laser element 19 Polygon scanner 20 Developing unit 20a Developing roller 30 Photosensitive drum 31 Primary charger 32 Pre-exposure lamp 33 Auxiliary charger 34 Cleaner 34a Cleaner blade 35 Transfer charger 36, 37 Tray 36a, 37a Feed roller 36b, 37b Transport roller 38 Pre-fixing belt 39 Fixing device 39a, 39b Heat / press roller 39c, 39d Roller Heaters 39e, 39f Temperature measuring device 40 Oil supply section 40a Oil tank 40b Oil heater 40c Temperature transmitter 40d Temperature measuring device 40e Application roller 41 Paper discharge tray 42 Belt after fixing 43
Multi-sheet feeder 44 Power supply unit 45 Heater control unit 71 Control means 71a CPU 71b ROM 71c RAM 71d Timer unit 72 Image input unit 102 Operation unit 103 A / D converter 105 High voltage control unit 107 Various motor control units 108 DC load control unit 109 Sensor signal processing section

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // B05C 1/02 102 B05C 1/02 102 F term (reference) 2H033 AA09 AA32 BA25 BA27 BA32 BA41 BA44 BB18 BB28 CA03 CA04 CA07 CA28 CA30 CA48 3K058 AA81 AA95 BA18 CA12 CA23 CA46 CA61 CB02 CB22 DA02 4F040 AA05 AB08 AC01 BA14 CB23 CB36 DA07 DA16

Claims (5)

[Claims] An image forming apparatus for developing an image by developing a latent image formed on a photoreceptor by an electrophotographic method with a developer, transferring the developed image onto a transfer material, and further heating and pressing with a fixing device to form an image. The fixing device includes a heating and pressing roller, a roller temperature adjusting unit that adjusts a heating temperature of the heating and pressing roller to a specified temperature, a roller heater driven by the roller temperature adjusting unit, and an oil to the heating and pressing roller. An oil supply unit for supplying, an oil temperature adjusting unit for adjusting the temperature of the oil to a specified temperature, and an oil heater driven by the oil temperature adjusting unit, while the roller heater is driven, An image forming apparatus comprising: a control unit that controls an oil temperature adjusting unit so as not to drive an oil heater. 2. A pair of the heating and pressing rollers are arranged so as to oppose each other so as to heat and press the image forming side and the opposite side of the passing transfer material, respectively, and each heating and pressing roller is provided with a roller heater. The image forming apparatus according to claim 1, wherein: 3. The controller according to claim 1, wherein the controller controls the oil temperature so that the oil heater is not driven while the roller heater for heating the heating and pressing roller disposed on the image forming side of the transfer material is driven. 3. The image forming apparatus according to claim 2, wherein the adjusting unit is controlled. 4. The roller heater disposed on the side opposite to the image forming side of the transfer material is independently adjusted to a specified temperature by a temperature adjusting unit irrespective of control by the control unit. The image forming apparatus according to claim 3. 5. The apparatus according to claim 1, wherein the control unit controls the roller temperature adjusting unit and the oil temperature adjusting unit such that the roller heater and the oil heater can be driven simultaneously when the image forming apparatus is heated up. The image forming apparatus according to claim 1.