JPH04204473A - Fixing device - Google Patents

Abstract

PURPOSE:To use a fixing device by switching a fixing speed to the fixing speed which is suitable for fixing the recording material of a resin' sheet without making the size of a device large by making a speed that the fixing speed is switched to the fixing speed of the recording material of the resin sheet faster than the speed that the fixing speed is switched to the fixing speed of a multi-use recording material. CONSTITUTION:When the recording material 56 is fed to the fixing device 40, the carrying speed of a carrying deck 33 and upper and lower fixing rollers 41 and 42 is changed to the fixing speed which is previously set. That means, in the case of a normal paper, a speed changing action is executed by a clutch 132 after a prescribed time (t4) from a time that a signal from a sensor 121 is inputted. In the case of an OHP paper, it is judged to be the OHP paper by an optical chucking sensor 122 disposed on a transfer drum 25, first. Thereafter, the speed changing action is executed only by the clutch 132 after the time (t5) from the time that the signal from the sensor 121 is inputted. Thus, the recording material of the resin sheet for OHP or the like is prevented from mistakenly entering a pair of fixing rollers without making the size of the device large.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fixing device that fixes and processes a toner image transferred onto a recording material. Fusing speed and overhead
The present invention relates to a fixing device that can be used by selectively switching to a fixing speed suitable for fixing a resin sheet recording material for a projector or the like.

(Prior Art) This type of fixing device is mainly used in image forming devices such as electrophotographic copying machines, laser beam printers, etc. that form color images, and warming-up is performed to ensure that the temperature of the pair of fixing rollers is uniform. It is driven at system speed for early start-up, and when forming images, it depends on whether the image is formed using a frequently used recording material, so-called plain paper, or a resin sheet recording material for overhead projectors (hereinafter referred to as OHP). , the fixing speed can be set to suit each.

By the way, the photoreceptor that transfers the image onto the recording material continues to be driven at the system speed, so in order to fix the recording i with the image transferred from the photoreceptor at a speed different from the system speed, the recording material must be moved to the transfer position. If fixing is not started after the time when the image is removed from the image, the difference in fixing speed will affect the image transfer.

To avoid this, it is necessary to provide a distance between the transfer section and the fixing device that is at least equivalent to the maximum paper size that can be passed through! Therefore, the conventional system has attempted to reduce the size of the apparatus by setting the switching point from the system speed to the fixing speed immediately before the recording material enters the pair of fixing rollers.

(Problems to be Solved by the Invention) However, according to the experience of the present inventors, in the case of resin sheet recording materials for OHP and the like, troubles have occurred due to failure or inability to enter the fixing roller pair. After repeated experiments and considerations on this issue, we found that resin sheet recording materials for OHP, etc. are made of resin sheets, and that the release oil applied to the fixing roller adheres to the tip, causing slippage between it and the fixing roller. Therefore, it was found that unlike plain paper, which can absorb adhering release oil, it has a tendency to be difficult to penetrate into the fixing roller. It has also been found that the speed of the fixing roller pair fluctuates immediately after the speed is changed, and tends to prevent a resin sheet recording material for OHP or the like from entering the fixing roller pair until the speed reaches a sufficiently low speed state.

Based on these findings, the present invention focuses on the fact that large-sized resin sheet recording materials for OHP and the like are not used, and the fixing speed of the fixing device with respect to the entry timing of the resin sheet recording material for OHP and the like. By setting a special switching point,
It is an object of the present invention to provide a fixing device that can solve the above problems without increasing the size of the device.

(Means for Solving the Problems) In order to achieve the above-mentioned problems, the present invention provides a fixing speed suitable for fixing frequently used recording materials and a fixing speed suitable for fixing recording materials on resin sheets based on the system speed. In a fixing device that can be selectively switched to, the timing of switching the fixing speed relative to the timing of the recording material entering the fixing roller pair is set to the fixing speed of the resin sheet recording material rather than the fixing speed of the frequently used recording material. This feature is characterized in that the switching time is faster.

(Function) The time point for switching to the fixing speed for resin sheet recording materials such as those for OHP is earlier than the time point for switching to the fixing speed for frequently used recording materials, which is set for the timing of entry of the recording material into the fixing roller pair. As a result, the resin sheet recording material for OHP etc. enters the fixing roller pair later than the entry timing of the frequently used recording material with respect to the time when the speed of the fixing roller pair is changed. Since it is difficult for the fixing roller pair to enter the fixing roller pair, the fixing roller pair is more stable and can enter the fixing roller pair when the speed is lowered.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a color copying machine 1 equipped with a developing device to which the present invention is applied. To give you an overview of this,
The copying machine 1 is equipped with four developing devices. An original placed on an original glass 2 is exposed to light by an exposure lamp 3 and a lens array 4 to a CCD line sensor 5, and is read as a color signal. This color signal is converted by the image processing circuit into a 3- or 4-value signal of Y (yellow), M (magenta), C (cyan), or K (black) added thereto, and the laser optical system 6 is transmitted as an output signal. The copying machine 1 of this embodiment does not have an image memory for three colors, and the image reader unit 7 repeats scanning every time when forming an image for each color, and based on this scan,
, M, C or Y, M, C, are transmitted to the laser optical system 6.

The laser optical system 6 includes a scanning polygon mirror 8, an fθ lens 9, a reflection mirror 10, etc., and emits laser light for image formation of each color based on the Y, M, C, or Y, M, C, signals. Exposure is performed by irradiating the photosensitive drum 11 with light. The photosensitive drum 11 is rotationally driven in the direction of the arrow.

The surface of the photosensitive drum 11 is provided with an organic optical semiconductor laminated on a conductive substrate, and is particularly sensitive to the wavelength of laser light used. Further, in this embodiment, the photosensitive drum 11 is negatively charged by the charging charger 12. Photosensitive drum 1
1, there are a drum cleaner 13, a toner collection roller 14, an eraser lamp 15, and a charging charger 12.
are arranged, and four types of developing devices are also arranged. The first developer 16 is cyan, the second developer 17 is magenta, the third developer 18 is yellow, and the fourth developer 1 is yellow.
Reference numeral 9 supplies black toner, and these toners are negatively charged.

Toner supply to each developing device 16 to 19 is performed by each developing device 1.
Toner of each color stocked in toner hoppers 20a to 20d corresponding to 6 to 19 is appropriately transported to each developing device 16 to 19 via a toner conveying pipe (not shown) according to each toner replenishment signal. This is done by

Recording materials 56 such as plain paper and OHP paper are stored in the paper feed cassette 2.
1a and 21b in a stacked state, and are set one by one in the manual feed cassette 80, and the paper feed rollers 22a and 2
2b etc., the sheets are fed into the copying machine 1 one by one. Then, the tip of the recording material 56 is connected to the registration roller 23.
By temporarily stopping the recording material 56 when it comes into contact with the recording material 56, the subsequent timing is measured and skew correction is performed at the same time. A paper sensor 24 is used for this purpose.

In order to sequentially transfer the C, M, and Y images formed on the photosensitive drum 11 onto the recording material 56, a transfer drum 25 is provided in the transfer section and is driven to rotate in the direction of the arrow. The transfer drum 25 has chunking claws 31 on its outer periphery for gripping the recording material 56, and has a suction charger 26 and a transfer charger 27 inside.
, a separation charger 28 is arranged. Further, a separation charger 30 is arranged outside the transfer drum 25 opposite to the separation charger 28 .

The electrostatic latent image formed on the photosensitive drum 11 by exposure by the laser optical system 6 is visualized by each of the developing devices 16 to 19 using a so-called reversal development method.

On the other hand, the recording material 56 fed from the registration roller 23 is gripped by the chucking claw 31 on the transfer drum 25, and is electrostatically wound onto the transfer drum 25 by the suction charger 26 as the transfer drum 25 rotates. . Then, the recording material 56 is transferred to the transfer charger 27.
and the photosensitive drum 11.
The toner image formed thereon is transferred to the recording material 56.

When obtaining a color image, the transfer drum 2 is placed on the recording material 56.
5, four transfer steps are performed one after another. After the transfer process has been completed, the recording material 56 is neutralized by the separation charger 28, 30, separated from the transfer drum 25 by the separation claw 32, and fed to the fixing device 4o by the transport deck 33.

The fixing device 40 includes an upper fixing roller 41 and a lower fixing roller 42.
, a cleaning roller 43, 44, an oil application unit 60, a separating claw 45, 46, an oil recovery blade 47, etc. The toner image transferred and formed on the recording material 56 is heated by upper and lower fixing rollers 41, 42. It is pressurized, fixed on the recording material 56, and discharged onto the paper discharge tray 35.

Further, as shown in FIGS. 2 and 3, the oil application unit 60 lubricates the nearly mirror-like elastic surface of the upper fixing roller 41 to reduce contact friction with the thermistor 71 and to offset the toner. It is made up of oil supply rollers 61, 62, oil application rollers 63, oil regulation blades 64, etc. Oil tank 365
The silicone oil as a mold release agent stored in
The oil is pumped up to the top and leveled by the oil regulating blade 64 to ensure an appropriate amount of application. Further, the oil application roller 63 is brought into pressure contact with the upper fixing roller 41 by a pressure contact control cam 65 that is driven in accordance with the timing when the recording material 56 is fed to the fixing device 40 and the timing of the initial rotation of the fixing roller when the power is turned on. Alternatively, the separation is controlled and the supply of oil to the upper fixing roller 41 is controlled.

Further, the oil regulating blade 64 also has an oil application roller 6 to prevent foreign matter from adhering to the oil regulating blade 64.
The pressure contact and separation with respect to 3 are controlled by a pressure contact control cam 66. Note that 71a is a thermistor in contact with the lower fixing roller 42.

The mechanism for performing the above control will be described in detail. The oil application roller 63 and oil supply rollers 61 and 62 that supply oil thereto are supported by a swing frame 73, which is pivotally supported by a shaft 74 on a fixed bracket 75. The fixed bracket 75 bears the rotation shaft 76 of the pressure contact control cam 65,660. Further, the oil regulating blade 64 is pivotally supported by the swing frame 73 at its base frame 376 by a shaft 77.

The swing frame 73 and the base frame 376 are biased clockwise in FIG. 2 by a spring 78 acting between them.
The respective driven pieces 73a and 76a are in pressure contact with the pressure contact control cams 65 and 66. As a result, the swing frame 7
3 and the base frame 376 are their passive pieces 73a.
, 76a, the swing frame 73 moves the oil application roller 63 toward and away from the upper fixing roller 41. Further, the base frame 376 is swung on the oscillating frame 73 to cause the oil regulating blade 64 to approach and separate from the upper fixing roller 41 .

The pressure contact control cams 65 and 66 that cause this contact and separation are performed by a cam operation control mechanism shown in FIGS. 4 and 5.

Drive from the main motor (not shown) is through gears 81 and 82.
It is transmitted to the spring clutch 83 via .

This spring clutch 83 is of a normally closed type. This clutch 83 has an outer cylinder 86 having pawls 86a at two locations on the circumference, and is connected to one end of a spring 87. In this state, the spring 87 is also tightened by the rotation of the gear 82, and the rotation cannot be transmitted to the cam drive shaft 89.

In other words, it is in an off state.

The clutch control pawl 88 is connected to the spring 92 by the solenoid 91.
When the outer cylinder 86 is rotated against the above-described locking, the spring 87 is immediately tightened and becomes an on state in which the rotation of the gear 82 is transmitted to the cam drive shaft 89.

Since the solenoid 91 is turned off again when the lock is released, the clutch control pawl 88 is biased by the spring 92 so that the pawl 86
It is immediately returned to the locked position with a.

Therefore, when the cam drive shaft 89 to which the rotational force has been transmitted rotates half a rotation, the pawl 86a engages with the clutch control pawl 88 and locks the outer cylinder 86, so that the spring clutch 83 is automatically turned off. be done.

Therefore, each time the solenoid 91 is turned on, the spring clutch 83 rotates the cam drive shaft 89 by half a rotation due to the rotation of the main motor. At the solid line position in FIG. 2, the oil application roller 63 is separated from the upper fixing roller 41, and the oil regulating blade 64 is separated from the oil application roller 63 and is in a non-operating state. In this state, when the solenoid 91 is turned on, the pressure control cams 65 and 66 are rotated half a turn to the position of the imaginary line, and the pressure control cam 66 is moved to the oil regulating blade 64.
After the oil application roller 63 is brought into pressure contact with the oil application roller 63, the pressure contact control cam 65 brings the oil application roller 63 into pressure contact with the upper fixing roller 41.

As a result, the oil application roller 63 is brought into pressure contact with the upper fixing roller 41 after the amount of oil supplied from the oil supply rollers 61 and 62 is regulated, and oil is applied to the upper fixing roller 41.

Therefore, no excess oil is applied to the upper fixing roller 41 even for a moment.

This oil application is carried out for a predetermined period of time 1.5 at the beginning of the rotation of the fixing rollers 41, 42 when the copying machine 1 is turned on first thing in the morning and the warming amplifier of the fixing rollers 41, 42 is performed. This is performed for a predetermined time L2 when the copying machine 1 passes the recording material through the fixing rollers 41 and 42 and performs fixing during image formation (FIG. 12). The oil application roller 63 is pressed against the upper fixing roller 41 by the cam drive shaft 8
This is confirmed by the position detection sensor 96 detecting the position display piece 95 provided at the position indicator 9 .

Said 1. The oil application between upper fixing rollers 41 and 42 is to lubricate the space between the upper fixing roller 41 and the thermistor in contact with it at the initial stage when the fixing rollers 41 and 42 are warmed up.
Initially, the temperature is low and the impregnated oil does not bleed out, so the nearly mirror-like elastic surface of the upper fixing roller 41 comes into close contact with the thermistor 71, creating a high friction state, which may cause abnormal noise or It is possible to avoid damage to the body surface.

However, the oil supply roller 61 during warming up.
62. The oil application roller 63 is driven by the drive mechanism 101 along with the drive of the main motor, but since it takes some time to reach the oil application roller 63 via the oil supply rollers 61 and 62, the oil application roller 63 is not used during warming up. 61. 62. It is preferable to delay the pressure contact of the oil regulating blade 64 to the oil applying roller 63 until the oil reaches the oil applying roller 63 from the time when the oil applying roller 63 starts rotating. - side fixing roller In 41 and 42, there is a slight delay from the start of rotation during warming up until the surface of the elastic body of the upper fixing roller 41 comes into close contact with the thermistor 71 and an abnormality occurs. If there is a delay, it is preferable to delay the start of rotation of the fixing rollers 41, 42 during the warming amplifier by the amount of the delay.

The oil application during the time t2 during the fixing is to prevent the toner on the recording material from adhering to the elastic surface of the upper fixing roller 41 and causing offset.

At this time, the oil application roller 63 is attached to the oil regulating blade 64.
Since the upper fixing roller 41 is pressed against the upper fixing roller 41 with the amount of oil being regulated by the pressure contact, no excess oil is applied to the upper fixing roller 41. Therefore, it is possible to avoid spoiling the transparency of images formed on OHP paper due to excessive oil. Further, the timing is adjusted so that the recording material enters the fixing rollers 41 and 42 at the same time that the oil application starting point of the upper fixing roller 41 reaches the fixing position opposite the lower fixing roller 42.

As a result, the oil applied to the upper fixing roller 41 reaches the fixing position almost at the same time as fixing starts.
It is possible to reliably prevent the toner on the recording material to be fixed from adhering to the surface of the upper fixing roller 41, and the oil applied to the upper fixing roller 41 is transferred to the lower fixing roller 42 before the start of fixing. It is possible to avoid a situation where the fixing roller reaches a position facing the lower fixing roller 42 and is wasted.

When the solenoid 91 is turned on again in the oil application state in the various cases described above, the pressure contact control cam 65.6
6 is rotated half a turn from the state shown by the imaginary line in FIG. 2 to the original solid line position, and the pressure contact control cam 65 separates the oil application roller 63 from the upper fixing roller 41 to immediately stop oil application, and then the pressure contact control cam 65 moves the oil application roller 63 away from the upper fixing roller 41 and immediately stops oil application. A cam 66 separates the oil regulating blade 64 from the oil application roller 63. It is preferable to set the timing for stopping oil application during fixing according to the size of the recording material to be fixed. According to this, the oil finally applied to the upper fixing roller 41 is applied to the fixing roller 41 regardless of the size of the recording material.
When the rear end of the recording material is fixed at 42, it reaches the part facing the lower fixing roller 42, and the supply of oil is completed with just the right amount.

Note that oil supply rollers 61 and 62, oil application roller 6
The drive mechanism 101 of No. 3 has a roller 61 as shown in FIG.
．． 63 at one end thereof, and a passive gear 105 directly connected to the other end of the uppermost oil application roller 63. The three connecting gears 102 to 104 are rotated by oil starting from the lowest gear 102 which is immersed in oil, so when a driving external gear is engaged with any of them, this external gear is also filled with oil. This may cause water to drip onto the outside. Therefore, a passive gear 105 directly connected to the uppermost roller 63 is provided,
The rotation of the drive gear 106 that meshes with an external gear and receives the drive of the main motor is controlled by the drive shaft 107 and the gear train 1.
The information is transmitted via 08. and drive gear 1
Since the transmission system from 06 to the gear train 108 is floating above the oil, it is possible to prevent the oil circulating around the connecting gears 102 to 104 from leaking out through the drive system.

The cleaning rollers 43, 44, which are in pressure contact with each of the fixing rollers 41, 42,
In particular, toner and paper powder that adhere to the surface of the upper fixing roller 41 little by little are removed without impairing the surface smoothness that is provided to ensure the quality of the transparent image formed on the OHP recording material 56 of the upper fixing roller 41. There is a need. In addition, it is preferable to take measures to prevent the generation of foreign matter such as hair when removing the cleaning material, which causes uneven oil application.

However, as conventional cleaning members, cleaning webs, release agent-filled rollers, release agent-impregnated rollers, and the like have been put into practical use. The materials used for the surface materials in all of these cleaning members are mainly fibers. The fibers used here have a large diameter and easily fall off and transfer to other places. In particular, when the surface elastic body has a high surface smoothness with a surface roughness of, for example, R252 μm, such as the upper fixing roller 41 that comes into contact with the upper fixing roller 41, conventionally used nonwoven fabrics and flocked cloths cannot prevent this hair loss. This is not possible and the roller surface will be damaged by the fibers. Furthermore, if an excessive amount of resin or the like is added between the fibers to prevent shedding, the original cleaning properties will be impaired. Therefore, the leaning characteristic described above cannot be obtained.

In order to satisfy this requirement, in this embodiment, as shown in FIG.
A cleaning surface material 114 and a roller core 11
Good results were obtained when 3 was a cylindrical body made of metal or heat-resistant resin, and the cleaning surface material 114 was wrapped with Miracle or Ecsaine (trade name, manufactured by Toshi Co., Ltd.). In short, as the surface material of the cleaning member, it is preferable to use a nonwoven fabric or a woven fabric whose surface member is mainly composed of polyester fibers having a diameter of 5 μm or less.

In addition, as shown in FIG. 7, cleaning rollers 43 and 44
When an intermediate elastic body 115 is provided between the roller core 113 and the cleaning surface material 114, the fixing roller 4
1.42 and the cleaning performance was improved along with the reduction of contact stress. The intermediate elastic body 115 is preferably made of noricorn rubber, fluororubber, silicone sponge, or the like.

Further, it is common practice to operate the fixing speed and the system speed at different speeds. For example, by setting the system speed at the time of warming up and forming a monochrome image, the temperature of the surface of the fixing roller 41, 42 can be set early during warming up to achieve a uniform temperature, and at the same time, the formation speed of a monochrome image that easily satisfies a predetermined image quality can be reduced. Don't be late. On the other hand, when forming a color image, the speed is reduced to 172 of the system speed when the recording material reaches the position just in front of the fixing device so that toner images of different colors can be sufficiently combined. Further, when forming a color image on OHP paper, the speed is further reduced to 1/4 of the system speed in order to obtain an image with particularly low light dispersion.

In this way, if you try to operate the fusing speed at a speed different from the system speed of the device, the distance from the transfer position of the developed image from the photoreceptor to the recording material to the fusing device is the maximum that the device can use. It becomes necessary to design the paper to be longer than the length of the paper.

For this reason, it is important to perform the speed change from the system speed to the fixing speed in the paper transport section as close to the fixing device as possible in order to downsize the device.

However, during gear shifting, it is unavoidable that the shifting speed will fluctuate due to mechanical or electrical factors in the transmission device.

Although this variation does not have a large effect on the paper passing stability of ordinary paper, it has a great effect on the paper passing stability of resin paper such as OHP paper. This effect is particularly noticeable in a fixing device where oil is applied because the applied oil prevents the fixing roller from entering.

Therefore, in this embodiment, when the recording material 56 is fed to the fixing device 40, the transport deck 33, the upper and lower fixing rollers 41, 42
The conveyance speed is changed to the preset fixing speed.

In that case, the sensor 121 provided on the transport deck 33
Shifting is performed by time control based on the signal from (Fig. 1) (Fig. 12).

In the case of plain paper, the speed change operation is performed by the flanks 131 and 132 after a predetermined time t4 from the time when the signal from the sensor 121 is input. Then, when the time required for the paper to be ejected has elapsed, the system speed is restored again.

01 (in the case of P paper, the OHP is
At t5 from the time when the signal from the sensor 121 is input after it is determined that the paper is paper, a speed change operation is performed only by the flange 132 (FIG. 12). Then, when the time required for the paper to be ejected has elapsed, the system speed is restored again.

It goes without saying that the time difference between L4 and t5 is sufficient time to reduce speed fluctuations during gear shifting.
In the color copying machine 1, it is approximately 1.5 seconds.

Further, detection of OHP paper, etc. may be performed based on a designation signal from the user.

The speed switching of the fixing device as described above is performed together with the transport deck 33 that supplies recording to the fixing device, so as to avoid problems in transferring recording materials between them. FIG. 8 shows a transmission device for changing the speed. I will discuss this. This device consists of two spring clutches 1
31, I32, clutch control pawl 133 that controls these
．． 134, and the clutch control pawl 133.134
are operated by solenoids (not shown), respectively.
Spring clutch 131 is normally open type,
The spring clutch 132 is of a normally closed type.

In the normal state where the spring clutches 131 and 132 are operating, the drive from the main motor is from drive gear 135 to gear 136, 137, and gear 138.1.
39 and is transmitted to the fixing device 40 and the transport deck 33.

When the recording material is ordinary paper, the clutch control pawls 134 and 135 act on the spring clutches 131 and 132 as the recording material enters the fixing device 40, and the spring clutch 1
31 is turned on and spring clutch 132 is turned off.

Therefore, the drive is from gear I35 to gear 141.142,
It will be transmitted through gears 138 and 139.

When the recording material is OHP paper, the clutch control pawl 134 is activated by the spring clutch 13 as the fixing device 40- enters.
2. Therefore, the drive is transmitted from the gear 135 to the gears 143, 144 and 138, 139.

This allows the above-mentioned high-speed operation to be performed.

9 and 10 show an overall view and a partially enlarged view of the operation panel 201 provided in the color copying machine 1. As shown in FIG.

Referring to FIG. 9, an operation panel 201 includes a print start key 202 for starting a copying operation, an interrupt key 203 for specifying interrupt copying, and a clear/stop key 20.
4. All reset key 205, numeric keypad 206, cent key 207, cancel key 208, various function keys 209.212, jog dial 213.2 for setting the area during trimming and masking], 4
, a display section 215 consisting of a liquid crystal display or the like that displays a document image and various messages is provided in order to set the il area. Here, the function keys 209 to 212 are used to specify magnification, paper specification, density adjustment, and the like. FIG. 10 shows an example of the display on the display section 215.

Here, when the function key 209 is pressed, the magnification designation mode 210 is pressed, and the paper designation mode 211 is pressed, the mode shifts to the density adjustment mode L'. For example, in the paper specification mode, the display section 215 displays A3, B4, A4, and B5.
The paper size is displayed in correspondence with the John keys 209 to 212, and the paper size can be selected using the function keys.

FIG. 11 is a block diagram of a control circuit for controlling the various operations, in which each input/output element is connected to a CPU 301, and control regarding the fixing device is performed according to the time chart shown in FIG. 12.

Note that the use of OHP paper may not be detected by the chucking sensor, and the operation corresponding to OHP paper may be performed by operating the leaf P mode designation key 302 provided on the operation panel 201.

In this embodiment, the oil application mechanism is operated for a predetermined time when the fixing roller is warmed up when the power is turned on, but if the power is turned on again relatively quickly after the last use. , the fixing roller may be in a state where oil lubrication is possible due to bleed-out even though the temperature has not dropped significantly. In such a case, it is possible to omit the spray coating based on the temperature information from the fixing roller. On the other hand, even when restarting the operation after a problem has been resolved, it is preferable to apply oil when the fixing roller is warmed up at a temperature below a predetermined temperature.

(Effects of the Invention) According to the present invention, the fixing speed of a frequently used recording material is such that the switching point to the fixing speed of a resin sheet recording material for OHP etc. is set to the timing of entry of the recording material into the fixing roller pair. Therefore, the resin sheet recording material for OHP etc. enters the fixing roller pair later than the entry timing of the frequently used recording material with respect to the time of switching the speed of the fixing roller pair. Therefore, since it is harder to rush into the fixing roller pair than the frequently used recording material, the fixing roller pair is more stable and can rush into the fixing roller pair when the speed is lowered, and it is possible to rush into the fixing roller pair of resin sheet recording materials such as those for Kano P. It is possible to prevent rushing mistakes. Also, 0) The entry timing of resin sheet recording materials such as those for IP use is later than that of frequently used recording materials.
Since resin sheet recording materials for OHP and the like can only be used in smaller sizes than multi-use recording materials, there is no need to increase the distance between the transfer section and the fixing device, and the image using the fixing device of the present invention can be There is no need to increase the size of the forming device.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a color copying machine equipped with a developing device to which the present invention is applied, Fig. 2 is a cross-sectional view showing the oil application mechanism of the fixing device, and Fig. 3 is a driving force transmission of the oil application mechanism. A perspective view showing the system, FIG. 4 is a sectional view of the driving force connection/disconnection mechanism of the oil application mechanism, FIG. 5 is a side view of the connection/disconnection operation mechanism of the driving force connection/disconnection mechanism, and FIGS. 6 and 7 are respectively 8 is a cross-sectional view of the speed switching mechanism of the fixing device, FIG. 9 is a front view of the operation panel of the copying machine, and FIG. 10 is a part of the operation panel. It is an enlarged view. FIG. 11 is a block diagram of the control circuit, and FIG. 12 is a time chart of operations related to the fixing device.

Claims (1)

[Claims] (1) In a fixing device that can be used by selectively switching from the system speed to a fixing speed suitable for fixing frequently used recording materials and a fixing speed suitable for fixing recording materials on resin sheets, the recording material enters the pair of fixing rollers. A fixing device characterized in that the timing point at which the fixing speed is switched is earlier when switching to the fixing speed for resin sheet recording material than when switching to the fixing speed for frequently used recording material. .