JP2002189371A - Fixing device and image forming device equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device for appropriately keeping the supply quantity of releasing agent to be an amount suitable for fixation, irrespective of standby time, continuous or directinous fixation, the quantity of the releasing agent stored in a releasing agent storage tank and the type of a sheet-like medium, and to provide an image forming device equipped with the fixing device. SOLUTION: The fixing device 1 is provided with a releasing agent applying member 32 for applying the releasing agent onto a sheet carrying member 2 for carrying the sheet-like medium and fixing a toner image, a supply member 52 for supplying the releasing agent to the member 32, and an attaching/ detaching mechanism 57 for attaching/detaching the supply member 52 to/from the member 32, and the image forming device is provided with the fixing device 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device and an image forming apparatus having the same, such as a copier, a facsimile, and a printer.

[0002]

2. Description of the Related Art Image forming apparatuses such as copying machines, facsimile machines, printers and printing machines generally have a fixing device for fixing a toner image on a sheet-like medium on which a toner image as an image to be fixed is formed. ing. The sheet-like medium includes a sheet as plain paper generally used for copying and the like, and an OHP
There is a so-called special sheet having a larger heat capacity than paper, such as a sheet, cardboard, and envelope.

[0003] The fixing device includes a heating roller having a heat source therein and driven to rotate, and a pressure roller pressed against the heating roller and rotated by the heating roller, and a nip formed by both rollers. A heat roller pair-type fixing device for fixing the toner image by applying heat and pressure to the sheet by rotating the rollers, an endless fixing belt and a fixing belt for conveying a sheet-like medium on which the toner is fixed. There is known a so-called belt fixing device of a type including a heating roller and a fixing roller around which a pressure roller is wound, and a pressure roller and the like arranged as opposed to the fixing roller via a fixing belt. Further, in these fixing devices, a roller-shaped release agent application member for applying a release agent for enhancing the releasability of a heating roller, a pressure roller, a fixing belt, and the like, and a release agent applied to the release agent application member. There is known a configuration in which a supply member connected to a release agent storage tank for supplying a mold agent is provided.

[0004]

However, since the conventional supply member is always in contact with the release agent applying member, if the standby time is long, the release agent may be stored due to gravity or surface tension. There is a problem in that the oil moves from the tank to the release agent applying member via the supply member, causing oil dripping. In addition, when the fixing is continuously performed, there is a problem that the supply of the release agent to the release agent application member cannot catch up, and the releasability is deteriorated. In addition, the problem that the release property is reduced also occurs when consumption of the release agent advances and the amount of the release agent in the release agent storage tank decreases, and the supply amount of the release agent decreases. . Further, an appropriate release agent supply amount differs depending on the type of the sheet medium.

According to the present invention, the supply amount of the release agent can be maintained at an amount suitable for fixing regardless of the standby time, the continuous fixing, the amount of the release agent in the release agent storage tank, and the type of the sheet medium. An object of the present invention is to provide a fixing device and an image forming apparatus including the same.

[0006]

In order to achieve the above object, according to the present invention, there is provided a release for applying a release agent to a sheet conveying member for fixing a toner image while conveying a sheet medium. A fixing device having an agent application member and a supply member for supplying a release agent to the release agent application member, further comprising a contact / separation mechanism for bringing the supply member into and out of contact with the release agent application member. I do.

According to a second aspect of the present invention, in the fixing device of the first aspect, a contact time of the supply member with the release agent applying member by the contact / separation mechanism is made variable according to a standby time. It is characterized by.

According to a third aspect of the present invention, in the fixing device according to the second aspect, the contact time is shorter as the standby time is longer.

The invention described in claim 4 is the first to third aspects of the present invention.
Wherein the contact time of the supply member with the release agent applying member by the contact / separation mechanism is made variable in accordance with the number of continuous sheets passed.

According to a fifth aspect of the present invention, in the fixing device of the fourth aspect, the contact time is longer as the number of continuous sheets passed is larger.

[0011] The invention according to claim 6 is the invention according to claims 1 to 5.
Wherein the contact time of the supply member with the release agent applying member by the contact / separation mechanism is variable according to the type of sheet medium.

According to a seventh aspect of the present invention, in the fixing device of the sixth aspect, the contact time is shorter when the type of the sheet medium is a special sheet than when the sheet is a plain paper. It is characterized by.

[0013] The invention according to claim 8 is the invention according to claims 1 to 7.
The fixing device according to any one of the above, further comprising at least the release agent storage tank among the supply member and the release agent storage tank that supplies a release agent to the supply member, and detachably attached to the fixing device main body. It has a free release agent supply unit.

According to a ninth aspect of the present invention, in the fixing device of the eighth aspect, there is provided a new detecting means for detecting that the release agent supply unit is new, and the release agent is provided by the contact / separation mechanism. The contact time of the supply member with respect to the application member, wherein the new detecting means is variable according to the consumption of the release agent after detecting that the release agent supply unit is new. I do.

According to a tenth aspect of the present invention, in the fixing device of the ninth aspect, the contact time is longer as the consumption amount is larger.

According to an eleventh aspect of the present invention, in the fixing device according to the ninth or tenth aspect, the novel detecting means includes a fusing member provided in the release agent supply unit and fusing by an ambient temperature in the fixing device main body. Detecting means for detecting the non-fused state of the fusing member.

According to a twelfth aspect of the present invention, in the fixing device according to any one of the first to eleventh aspects, there is provided an endless fixing belt for conveying a sheet-like medium on which a toner image is fixed, and the fixing device. The fixing device further includes a heating roller and a fixing roller around which a belt is wound, and a pressure roller disposed to face the fixing roller via the fixing belt, wherein the sheet conveying member includes the fixing belt and / or the heating roller. It is a pressure roller.

According to a thirteenth aspect of the present invention, in the fixing device according to any one of the first to eleventh aspects, a heating roller for heating and conveying the sheet-like medium on which the toner image is fixed is provided. A pressure roller pressed against the heating roller, wherein the sheet conveying member is the heating roller and / or the pressure roller.

According to a fourteenth aspect of the present invention, there is provided an image forming apparatus having the fixing device according to any one of the first to thirteenth aspects.

[0020]

FIG. 1 schematically shows a fixing device to which the present invention is applied and an image forming apparatus having the fixing device. The image forming apparatus is a well-known one such as a copying machine, a facsimile, a printer and the like, and may be any type of image forming apparatus that can use a fixing device to which the present invention is applied.
The image forming apparatus of this embodiment can form a color image.

The image forming apparatus 20 includes image forming apparatuses 21Y, 21M, and 21 that form an image for each color according to a document image.
C, 21BK and image forming devices 21Y, 21M, 21C, 2
1BK, and a sheet supply unit for supplying various sheet-like media to a transfer area where the image forming units 21Y, 21M, 21C, 21BK and the transfer unit 22 face each other. Paper cassettes 23, 24,
A registration roller 3 that supplies the sheet-shaped medium conveyed from the paper feed cassettes 23 and 24 at the timing of image formation by the image forming apparatuses 21Y, 21M, 21C, and 21BK.
0, and a fixing device 1 for fixing the sheet medium after the transfer in the transfer area.

The image forming apparatus 20 includes plain paper (hereinafter simply referred to as plain paper) generally used for copying or the like, 90K paper such as an OHP sheet, a card, and a postcard, and a basis weight of about 10
Any of so-called special sheets (hereinafter, simply referred to as special sheets) having a heat capacity larger than that of paper, such as thick paper of 0 g / m ² or more, and envelopes, can be used as the sheet-like medium.

Each of the image forming devices 21C, 21Y, 21M, 21
BK develops the respective colors of cyan, yellow, magenta, and black, and uses different toner colors.
The configuration of the image forming apparatus 21C, 21Y, 21M, 21B
This will be described as a representative of K. The image forming device 21C includes a photosensitive drum 25C as an electrostatic latent image carrier, and a photosensitive drum 25.
Exposure by scanning means including a well-known charging device (not shown), a developing device, a cleaning device, and the like which are sequentially arranged in the rotation direction A of C, and a well-known polygon mirror (not shown) between the charging device and the developing device. This is a known configuration that receives the light 29C. The electrostatic latent image carrier may have a belt shape instead of a drum shape. However, the exposure light 29BK in the black image forming device 21BK can be two beams, and the image forming device 21BK is used for each of the other image forming devices 21Y and 21Y.
It is possible to form images faster than 1M and 21C.

An A4-size sheet medium is placed on the sheet cassette 23, and an A3-size sheet medium is placed on the sheet cassette 24 such that the left-right direction in the drawing is the longitudinal direction. The transfer device 22 is disposed in an oblique direction so that the image forming device 20 is small in the left-right direction in the drawing, and the sheet-like medium conveyance direction indicated by the arrow B is oblique. Thus, in the image forming apparatus 20, the width of the housing 26 in the left-right direction in the figure is slightly longer than the length of the A3-size sheet-shaped medium in the longitudinal direction. That is, the size of the image forming apparatus 20 is reduced to a minimum necessary for accommodating the sheet-like medium therein, thereby being greatly reduced in size. The upper portion of the housing 26 serves as a paper discharge tray 27 for stacking a sheet-like medium that has passed through the fixing device 1 and has a toner image fixed thereon.

In FIG. 1, reference numerals 41 and 42 denote pick-up rollers for feeding a sheet-like medium from the paper feed cassettes 23 and 24, respectively, a reference numeral 43 denotes a conveying roller for taking over the sheet-like medium, and a reference numeral 44 denotes a feeding roller. Reference numeral 4 denotes a roller structure that conveys the sheet-like medium conveyed from the paper cassettes 23 and 24 toward the registration roller 30.
Reference numeral 5 denotes a discharge roller for discharging the sheet-shaped medium from the opening indicated by reference numeral 46 to the discharge tray 27 to the outside of the housing 26.

As shown in FIG. 2, the fixing device 1 includes an endless fixing belt 2 as a sheet conveying member for conveying a sheet medium to which toner is fixed, and a heating roller around which the fixing belt 2 is wound. 3, a fixing roller 4, a pressure roller 5 disposed opposite to the fixing roller 4 via the fixing belt 2, a heating roller 3, heaters 6 and 7 provided inside the pressure roller 5, A thermistor 8 as a temperature detecting means for detecting the temperature of the heating roller 3, which is disposed to face and contact the roller 3; and a cleaning roller 3, which is disposed to face the fixing roller 4 via the fixing belt 2.
1. An application roller 32 as a release agent application member, a release agent supply unit 50 for supplying a release agent to the application roller 32, a casing 33, an inlet guide 12 fixed to the casing 33, and an outlet guide 36. A handle 37, a support 38 for integrally supporting the heating roller 3, the fixing roller 4, and the fixing belt 2, a support 38 for the casing 33, a support 39 for supporting the pressure roller 5, and the like. I have.

To apply an appropriate predetermined tension to the fixing belt 2, the heating roller 3 and the fixing roller 4 are urged away from each other by an elastic body (not shown) such as a spring. The fixing roller 4 includes a metal core 9 and a heat-resistant elastic layer 10 covering the metal core 9 and forming the surface of the fixing roller. By being driven to rotate, the fixing roller 4 is driven to rotate in the direction of arrow C, and the fixing belt 2 is driven in the direction of arrow E by the driven rotation of the heating roller 3 in the direction of arrow D. The application roller is driven to rotate in the direction of arrow G in the direction of arrow F of the pressure roller.

The pressure roller 5 and the fixing roller 4 are configured such that the support body 38 and the support body 39 are urged toward each other by an elastic body (not shown) such as a spring.
It is urged with a pressure contact force of 10 kgf or more in a direction in which they are pressed against each other. The pressure roller 5 has two apexes with the axis of the fixing roller 4 as the apex, and two straight lines connecting the axis of the fixing roller 4 and the axis of the heating roller 3 and the axis of the heating roller 3 and the axis of the pressure roller 5, respectively. The fixing roller 4 is in contact with the fixing roller 4 such that the corner between the fixing roller 4 and the fixing roller 4 forms an acute angle. A first fixing portion 15 that contacts only the belt 2 and a second fixing portion 16 where the pressure roller 5 contacts the fixing roller via the fixing belt 2 are formed.

The casing 33 is provided at a position facing the transfer device 22, and sandwiches the opening 34 for receiving the sheet-like medium conveyed by the transfer device 22, the first fixing unit 15 and the second fixing unit 16. An opening 35 provided on the opposite side of the opening 34 for discharging the fixed sheet medium.
And The entrance guide 12 has an opening 3 at its base.
4, is fixed to the outer surface of the casing 33, and the tip enters the inside of the casing 33 through the opening 34,
The fixing portion 15 extends toward the fixing portion 15.

The fixing belt 2 is made of nickel and has a thickness of 100 mm.
A release layer made of silicon rubber of 200 μm is formed on a substrate of μm, which has a small heat capacity and good thermal responsiveness. The length of the fixing belt 2 is such that the diameter of the fixing belt 2 becomes 60 mm when the belt 2 has a circular shape. The substrate may be made of SUS or polyimide. The thickness may be about 30 to 150 μm in consideration of flexibility.
The release layer has a thickness of 50 to 30 when silicon rubber is used.
0 is desirable, and when a fluororesin is used, the thickness is 1
About 0 to 50 μm is desirable. Further, the release layer may have a configuration in which a fluororesin is laminated on silicon rubber. It is desired that the fixing belt 2 is heated instantaneously and the surface of the belt is self-cooled in the fixing area to the extent that hot offset does not occur. On the other hand, in the fixing area, the toner is sufficiently melted and fixed. Must have the necessary heat capacity for The above-mentioned material and thickness of the fixing belt 2 satisfy this condition. Self-cooling refers to a phenomenon in which the belt cools in the fixing process due to the absence of a heating source on the unfixed image side of the sheet medium in the fixing area.

The fixing belt 2 is given a tension of 3 kgf / one side because the heating roller 3 and the fixing roller 4 are urged so as to be separated from each other. This tension can be set by adjusting the urging force of the elastic body (not shown), from 1 kgf (9.8 N) to 3 kgf (29.
4N) is preferable for good fixing.

The heating roller 3 and the pressure roller 5 are each made of a thin cylindrical cored bar to reduce the heat capacity. The diameter of the core of the heating roller 3 is 20 mm or more and 30 mm or less, the thickness of the concentric metal is 0.3 mm or more and 2.0 mm or less, and the diameter of the core of the pressure roller 5 is 30 mm or more and 50 m.
m or less, and the thickness of the concentric metal is 0.3 mm or more and 1.5 mm
It is as follows. Thereby, the heat capacity of the heating roller 3 becomes 26
cal / ° C. or less, heat capacity of the pressure roller 5 is 36 cal
/ ° C or less.

In the present embodiment, the core metal of the heating roller 3 is made of aluminum and has a diameter of 30 mm and a thickness of 0.1 mm.
7 mm. It is preferable that the material has a low specific heat and a high thermal conductivity, and other metals such as iron, copper, and stainless steel can be used. In addition, when the roller diameter is 30 mm made of aluminum, the thickness is 0.6 mm or more.
When the roller diameter is 20 mm, the wall thickness is 0.7 mm to 1.4 mm when the roller diameter is 1.4 mm, and the wall thickness is 0.3 mm to 0.9 mm when the roller diameter is 30 mm. Can be set. The reason why the wall thickness is reduced as the diameter increases is in consideration of the axial bending of the roller.

The lower limit of the thickness is an allowable value in consideration of the deformation of the heating roller 3 due to the tension of the fixing belt 2, and the upper limit is an allowable value for obtaining a desired rise time. I have. The reason why the roller diameter is set to 20 mm or more is to secure the belt tension so that the roller does not bend in the axial direction. Roller diameter is 20mm
The reason for setting the sheet-like medium conveyance speed to 200 mm
mm / s or less, the fixing belt 2 even during continuous paper passing
26ca to keep the temperature of the toner at a constant temperature required for fixing.
This is for obtaining a heat capacity of about 1 / ° C.

By setting the heat roller 3 to have a low heat capacity as described above, even if the fixing belt 2 rotates, heat is hardly taken away, and adverse effects on fixing and prolonged rise time are prevented. . Further, even if the temperature is lowered due to continuous fixing or the like, the time until recovery is shortened. The heater 6 heats the fixing belt 2 via the heating roller 3 and the heating roller 3. The temperature of the heater 6 is input to a control unit (not shown) as a detection signal by the thermistor 8 and is compared with a target fixing temperature. When the detected temperature is lower than the fixing temperature, the power supply to the heater 6 is performed. When the detected temperature is higher than the fixing temperature, the power supply to the heater 6 is stopped. The fixing temperature is controlled by feeding back the detection signal of the thermistor 8 in this manner, and the fixing belt 2
Is maintained at 110 ° C. or higher. Note that the thermistor 8 is in contact with the heating roller 3 at an obtuse angle with respect to the rotation direction of the heating roller 3 so as to reduce mutual wear caused by the rotation of the heating roller 3.

The heating roller 3 has an alumite layer as a hard protective film on the outer surface. This alumite layer was formed by anodic electric field treatment, and had a Vickers hardness H
V200 or higher. When the heating roller 3 does not have an alumite layer, the heating roller 3 wears due to friction with the fixing belt 2. However, the formation of the alumite layer prevents such abrasion. In the experiment, it was confirmed that aluminum powder was not generated due to abrasion even after passing 60,000 sheets. Further, a black alumite layer can be formed by performing an alumite treatment on the inner surface of the heating roller 3, thereby preventing heat reflection by the heater 6 on the inner surface of the heating roller 3 and increasing the heat absorption rate of the heating roller 3. As a result, the thermal efficiency can be increased, and breakage of the heater 6 due to excessive temperature rise can be prevented. The black alumite treatment inside the heating roller 3 can be performed simultaneously with the outer surface.

The elastic layer 10 of the fixing roller 4 is a rubber layer made of rubber. The material is specifically made of silicone sponge rubber. That is, it is a foam, and the diameter of the bubble is 500 μm, and particularly the diameter in the vicinity of the surface, ie, in the vicinity of the peripheral surface of the fixing roller 4 is 300 μm or less. When the elastic layer 10 is a foam, a decrease in the temperature during fixing is suppressed. On the other hand, since the foam is a foam, a fixing pressure cannot be obtained, gloss is not obtained, and the surface is rough and gloss unevenness occurs. Although a defect may occur, defects such as poor gloss and uneven gloss are prevented because the foam diameter is set as described above.

Since the elastic layer 10 in this embodiment is molded by mixing a foaming agent into a rubber material in a mold and foaming, a non-foamed layer of about 1 mm called a skin layer is formed on the surface. The structure is such that the degree of foaming increases toward the inside. The vicinity of the surface where the foaming diameter is 300 μm or less refers to the surface portion of the elastic layer 0
It refers to a portion that affects gloss unevenness due to its density. In addition, as a method of molding the elastic layer 10, there is a method in which the above-mentioned skin layer is not formed. According to this method, the outer diameter accuracy is improved and the cost can be reduced. Also in this case, it is possible to mold a foam having the same foam diameter as described above and apply it to the fixing device 1.

The surface hardness of the elastic layer 10 is 20
HS or higher. In the case of Asuka C20HS or more, not only when the elastic layer 10 has a skin layer but also when it does not, the surface roughness due to the elastic layer 10 being a foam affects the image quality. This is because a good fixed image can be obtained by preventing gloss unevenness. The fixing roller 4 has an outer diameter of 30 mm. Elastic layer 1
No. 0 is a heat-resistant porous elastic body with low thermal conductivity and heat insulation, so it reduces the heat loss of the belt, reduces the temperature drop after rising, and performs pre-rotation for temperature recovery. Saves time. Further, since the elastic layer 10 has a relatively low hardness, a sufficient nip width can be obtained even when the pressing force of the pressure roller 5 is small, and good fixing performance can be obtained even under a relatively low temperature and low pressure condition. Obtainable.

The core of the pressure roller 5 is made of iron and has a diameter of 40 mm and a thickness of 1.0 mm. It is preferable that the material has a low specific heat and a high thermal conductivity, and other metals such as aluminum, copper, and stainless steel can be used. In addition, when the roller diameter is 30 mm made of iron, the thickness is in the range of 0.4 mm to 1.0 mm. When the roller diameter is 50 mm, the thickness is 0.3 mm to 0.8 mm in the case of iron. When the roller diameter is 30 mm, the thickness is in the range of 1.3 mm to 1.5 mm, and when the roller is made of aluminum and the roller diameter is 50 mm, the thickness is 0.6 mm to 1.2 m.
m can be set. The reason why the wall thickness is reduced as the diameter increases is in consideration of the axial bending of the roller.

The lower limit of the thickness is an allowable value in consideration of the deformation of the pressure roller 5 due to the surface pressure of 0.6 kg / cm ² corresponding to the lower limit of the fixing pressure, and the upper limit is a desired value. An allowable value for obtaining a rise time is shown. The reason why the roller diameter is set to 30 mm or more is to secure the fixing pressure so that the roller is not bent in the axial direction. The reason why the roller diameter is set to 30 mm to 50 mm is that the fixing belt 2 keeps a constant temperature necessary for fixing even during continuous paper feeding when the sheet-like medium conveying speed is 200 mm / s or less. / ° C.

By setting the pressure roller 5 to have a low heat capacity in this way, even if the fixing belt 2 rotates, heat is hardly taken away. In particular, in the present embodiment, since the pressure roller 5 has the heater 7, This prevents the temperature of the fixing belt 2 from being lowered to adversely affect the fixing, and prevents the rise time from being prolonged. Further, even if the temperature is lowered due to continuous fixing or the like, the time until recovery is shortened. The heater 7 raises the temperature of the pressure roller 5, shortens the rise time, and also supplies heat from the back surface of the sheet-shaped medium at the time of fixing to obtain more stable fixing performance. The pressure roller 5 can form a release layer of 10 μm to 300 μm on a cored bar. The heater 7 heats the pressure roller 5, and energization is controlled in synchronization with the heater 6.
The fixing temperature is controlled.

The reason why the heat roller 3 and the pressure roller 5 can be made thinner to reduce the heat capacity is that the fixing device 1 is a so-called belt fixing device using the fixing belt 2.
That is, since the fixing is performed by relatively long portions such as the fixing units 15 and 16, the fixing pressure can be reduced, and the strength of the pressure roller 5 can be reduced.
Further, since the heating roller 3 is not pressed against the pressure roller, the thickness of the heating roller 3 can be reduced. Performing the fixing at a relatively long distance portion enables fixing at a relatively low temperature, which also contributes to shortening the rise time. Further, when the fixing belt 2 is used, there is an advantage that the fixing belt 2 heated by the heater is cooled to a temperature suitable for fixing in a process of being conveyed, and offset can be prevented. Heaters 6, 7
Is 700W considering the inrush current when the power switch is turned on and the flickering phenomenon of the fluorescent lamp when the heater is turned on and off.
It is as follows.

Cleaning roller 31 and coating roller 32
The cleaning roller 31 is located upstream of the application roller 32 in the moving direction of the fixing belt 2. Both the cleaning roller 31 and the application roller 32 are always fixed to the fixing belt 2.
Is in contact with The cleaning roller 31 has a diameter of 20 m
The driving unit (not shown) is driven to move in a direction opposite to the moving direction of the fixing belt 2 at a portion facing the fixing belt 2. Thus, the toner transferred to the fixing belt 2 from the sheet medium is scraped. The toner scraped off from the fixing belt 2 by the cleaning roller 31 is wiped off from the cleaning roller 31 by a cleaning means (not shown) so that the cleaning roller 31 can always perform good cleaning. The application roller 32 is for applying a release agent to the fixing belt 2, has a diameter of 16 mm, and is driven to rotate by the fixing belt 2.

The release agent supply means 50 includes a tank 51 serving as a release agent storage tank storing a release agent containing silicon oil as a main component, and one end immersed in the release agent in the tank 51 and the other end coated. Felt supply member 52 in contact with roller 32
And almost all of the tank 51 and the supply member 52 were accommodated,
A housing 53 detachable from the body of the fixing device 1;
3 having a metal fusing member 54 fixed to the outside,
These constitute a release agent supply unit detachable from the fixing device 1 main body. The supply member 52 supplies the release agent in the tank 51 by applying it to the application roller 32 by the capillary phenomenon.

When the release agent sharing means 50 is mounted on the fixing device 1 main body, the fusing member 54 is connected to a receiving portion 55 as a connector which is engaged with one end of the fusing member 54, and is provided on the casing 33. Electrically connected to the substrate 56 as The fusing member 54 is located above the heating roller 3. When the temperature of the heating roller 3 rises and the ambient temperature in the fixing device 1 body around the fusing member 54 becomes approximately 70 ° C. or more, the fusing member 54 is cut off. It has become. Fusing member 54
Has been detected by the substrate 56, and the substrate 56 notifies the control means that the fusing member 54 has blown.

When the release agent in the tank 51 is consumed, the release agent supply means 50 is replaced with a new one. At this time, since the fusing member 54 also becomes new, a new release agent supply means 50 is provided. When the means 50 is mounted on the fixing device 1 body, the substrate 56
Detects the current supply by the new fusing member 54, that is, the non-fusing state of the fusing member 54. Thereafter, when preheating described later is performed in the fixing device 1 and the fusing member 54 is melted and the energized state is released, the substrate 56 detects this and sends it to the control means. The control means detects that the new release agent supply means 50 is mounted by receiving the fusing of the fusing member 54, and at this time, resets the number of image forming sheets, in other words, the number of fixing sheets, and newly counts the number of fixing sheets. Begin to. The fusing member 54, the substrate 56, and the control unit are connected to the release agent supply unit 5.
0 constitutes a new detection means for detecting that it is new.

As shown in FIG. 3, the fixing device 1 has a contact / separation mechanism 57 for moving the supply member 52 toward and away from the application roller 32. The contact / separation mechanism 57 includes a tension spring 5 having one end fixed to the casing 33 and the other end fixed to the housing 53.
8, one end of which engages with a convex portion 59 protruding from the housing 53,
A swing member 61 swinging about a shaft 60, and a swing member 61;
, A solenoid 63 fixed to the casing 33 and engaged with the other end of the tension spring 62, and a shaft portion 64 protruding from the housing 53 and serving as a swing center thereof And The solenoid 63 is normally in a non-energized state. In a normal state, the housing 53 is pulled upward by the tension spring 58 and swings upward around the shaft portion 64, so that the supply member 52
3, when the solenoid 63 is energized, the solenoid 63 swings the swing member 61 via the tension spring 62 against the urging force of the tension spring 58, as shown in FIG. When the convex portion 59 is pressed down, the supply member 52 comes into contact with the application roller 32 to supply the release agent.

The energization control for the solenoid 63 is performed by the above-described control means as follows. That is, the contact time of the supply member with respect to the application roller 32 is determined by the energizing time of the solenoid 63, and the energizing time is the standby time of the image forming apparatus 20, the number of continuous images formed by the image forming apparatus 20, in other words, the fixing apparatus 1 It is variable according to the number of sheets continuously fed to the printer, the type of sheet medium to be fixed, and the number of sheets fixed after the release agent supply means 50 is replaced with a new one.

More specifically, as for the standby time of the image forming apparatus 20, the longer the standby time, the shorter the energization time, the shorter the contact time of the supply member, and the more the release agent supply amount to the application roller 32. Try to reduce. Concerning the number of continuous sheets passed, the larger the number of continuous sheets passed, the longer the energizing time, the longer the contact time of the supply member, and the more the amount of release agent supplied to the application roller 32. Regarding the type of the sheet medium, the energizing time is shortened in the case of the special sheet, specifically, the OHP sheet, and the contact time of the supply member is shortened as compared with the case of the plain paper. To reduce the supply amount of the release agent. Regarding the number of fixings after replacing the release agent supply means 50 with a new one, the larger the number of fixings, the longer the energizing time and the longer the contact time of the supply member, and the more the number of fixings. Attempt to increase the agent supply.

In this embodiment, the control means controls the energization of the solenoid 63 in accordance with the control table shown in FIG. 4 which is recorded in the ROM as the recording means connected to the control means. . For example, when the standby time is less than one hour and the number of used release agent supply units, that is, the number of fixed images after the release agent supply unit 50 is replaced with a new one, is less than 5,000, FIG. 4 (a), and the number of continuous sheets passed is 50.
If it is up to the number of sheets, it is determined from FIG. 4B that the energizing time is 30%, and energizing control of the solenoid 63 by the control means is performed. When the sheet medium is an OHP sheet, the energization is performed in half the time shown in FIG. 4, and in the above case, the energization is performed at 15% which is half of 30%. When the duty is 100%, power is always supplied during a job, and the printer is in a normal contact state.

Here, the standby time means that the operator starts image formation after the driving system in the image forming apparatus 20, for example, the photosensitive drum 25 is stopped after the last sheet is discharged in the previous image formation. To perform a known operation, for example, pressing a start key. It is determined whether or not continuous paper passing has been performed if the time from the discharge of the last sheet to the start of the next image formation operation is within 30 seconds. It is determined that a new paper feed has started. The timing for starting the energization of the solenoid 63 is set to a predetermined time after the registration roller 30 sends out the sheet-shaped medium.
As a result, a sufficient time for the toner to be applied to the fixing belt 2 without unevenness is secured. As the fixing is repeatedly performed, the release agent in the tank 51 is consumed. The consumed amount is detected by converting the number of image forming sheets, in other words, the number of fixed sheets into the consumed amount. In addition, the absence of the release agent in the tank 51 means that the number of fixings reaches a predetermined number or that the motor for driving the fixing roller 4 reaches a predetermined number of rotations, whichever comes first. Is detected at the timing of, and when this is detected, the image forming apparatus 20
On the display means (not shown) provided outside, a message indicating that the release agent supply means 50 should be replaced with a new one is displayed. The duty of 100% refers to a state in which the sheet-shaped medium is kept energized until a rear end of the sheet-shaped medium is discharged from the fixing device 1 after a lapse of a predetermined time from the registration roller 30.

Therefore, for each sheet-like medium, duty, in other words, based on the control table shown in FIG.
The energizing time for the solenoid 63 is determined, and after a predetermined time has elapsed after the sheet-shaped medium is sent out from the registration roller 30, energization to the solenoid 63 is performed for the determined energizing time. The timing at which the rear end of the sheet-shaped medium is discharged from the fixing device 1 is determined by a predetermined time after the sheet-shaped medium is sent out from the registration roller 30 according to the size of the sheet-shaped medium and the conveyance speed of the fixing belt 2. It is assumed that the passage of time has elapsed, and a sensor for detecting the passage of the sheet-like medium is disposed near the opening 35 of the fixing device 1. It can also be when the trailing end is ejected.

By controlling the contact / separation mechanism 57 in this manner, the supply member 52 is moved toward and away from the application roller 32 so that the application roller 3
The amount of the releasing agent supplied to the fixing roller 2 is adjusted, and the amount of the releasing agent supplied to the fixing roller 2 is maintained at an amount suitable for fixing, thereby performing satisfactory fixing.
Specifically, since the contact time is shorter as the standby time is longer, when the standby time is longer and the release agent is sufficiently impregnated into the supply member, the supply member 52 is brought into contact with the application roller 32 for a shorter time. When the release time is short and the release agent is not sufficiently impregnated in the supply member 52, the supply member 52 is brought into contact with the application roller 32 for a long time, so that the release agent is applied to the application roller 32 regardless of the standby time. The supply amount is adjusted to an appropriate amount, the supply amount of the release agent to the fixing belt 2 is maintained at an amount suitable for fixing, and good fixing is performed.

Further, since the contact time is longer as the number of continuous sheets passed is large, the number of continuous sheets passed is large and the release agent on the fixing belt 2 is consumed quickly, so that the release agent from the application roller 32 to the fixing belt 2 is discharged. When the transfer is fast, the supply member 52 is
To the coating roller 3
When the supply of the release agent to the fixing belt 2 is sufficient even if the supply amount of the release agent to the
2 for a short time, the release agent supply amount to the application roller 32 is adjusted to an appropriate amount irrespective of the number of continuous sheets passed,
The supply amount of the release agent on the fixing belt 2 is maintained at an amount suitable for fixing, and good fixing is performed.

The contact time is determined by the type of the sheet medium.
Since the OHP sheet is shorter than the other sheets, the sheet medium is the OHP sheet and the consumption of the release agent is small, and the supply amount of the release agent to the application roller 32 is small. When the supply of the release agent to the fixing belt 2 is sufficient, the supply member 52 is brought into contact with the application roller 32 for a shorter time than the other sheets, so that the supply amount of the release agent to the application roller 32 is adjusted to an appropriate amount. Adjustment is performed, and the supply amount of the release agent on the fixing belt 2 is maintained at an amount suitable for fixing, and good fixing is performed.

Since the contact time is longer as the consumption of the release agent is larger, the number of sheets fixed after the replacement of the release agent supply means 50 is large, and the release agent in the tank 51 is consumed and decreased. When the supply member 52 is no longer sufficiently supplied, the supply member 52 is brought into contact with the application roller 32 for a long time, and the number of fixings after the replacement of the release agent supply means 50 is small, and the amount of the release agent in the tank 51 is reduced. When the supply member 52 is sufficiently supplied to the supply member 52, the supply member 52 is brought into contact with the application roller 32 for a short time, so that the release agent supply amount to the application roller 32 according to the release agent amount in the tank 51 is reduced. The fixing amount is adjusted to an appropriate amount, and the supply amount of the release agent to the fixing belt 2 is maintained at an amount suitable for fixing, and good fixing is performed.

The fixing device 1 includes a type of toner for forming a toner image formed on a sheet medium in the main body of the image forming apparatus 20, a resolution of the toner image, and a type of a sheet medium on which the toner image is formed. Has a plurality of fixing modes determined according to In the present embodiment, the type of toner means whether the type of toner used in the main body of the image forming apparatus 20 is black used in the image forming apparatus 21BK, that is, black toner,
Y, 21M, 21C, and 21BK, which means any of yellow, magenta, cyan, and black toners. That is, the type of the toner that forms the toner image means whether the toner image is a black image or a full-color image. Further, the resolution of the toner image is any of 600 dpi and 1200 dpi, and the type of the sheet medium is any of the above-described plain paper and special sheet. The fixing device 1 has a plurality of, specifically, eight fixing modes according to a combination of these conditions.

In accordance with each fixing mode, a set temperature for performing fixing, that is, a target fixing temperature and a conveying speed in the above-mentioned control means, that is, a conveying speed of the sheet-like medium by the fixing belt 2, in other words, a moving speed of the fixing belt 2 Is stipulated. Fixing temperatures are 160 ° C, 150 ° C, 1
30 ° C., the transport speed is 185 mm / s,
It is either 125 mm / s or 62.5 mm / s. The transport speed is made variable by adjusting the rotation speed of the fixing roller 4.

Exposure or writing with two beams in the image forming apparatus 21BK is performed in a mode in which the transport speed is 185 mm / s. Such high-speed transport can be achieved by performing writing using two beams. Also 18
The transport speed of 5 mm / s is a limit speed determined by the maximum rotation speed of the polygon mirror provided in the image forming apparatus 21BK. Since an image forming apparatus that performs writing using two beams is expensive, the most frequently used black image forming apparatus 2 is used.
Only 1BK can perform writing by two beams.

When a full-color toner image is formed, the other image forming devices 21C and 21C can be used in the image forming device 21BK.
Since one-beam writing is performed in the same manner as in 21Y and 21M, when forming a 600 dpi toner image, the conveyance speed is set to 125 mm / s, which is lower than 185 mm / s in the fixing mode 1, and the 1200 dpi toner image is printed. In the case of forming, the transfer speed is half that of 6
It is 2.5 mm / s. The fixing temperature is set to be the highest temperature in a range where hot offset does not occur at each transport speed. This is desirable when a full-color image is formed, in which the glossiness of the image is preferably high, and it is also effective to apply a large amount of heat to increase the glossiness.
Since the heat capacity of the special sheet is larger than that of the plain paper, the amount of heat supplied is increased by lowering the conveying speed or increasing the fixing temperature. Also, especially when the special sheet is thick paper, the transport speed is always 62.5 m.
m / s.

In this embodiment, the control means automatically switches between the fixing modes for the type of toner for forming the toner image in accordance with the document information of the toner image to be formed. The operator selects either a black image or a full-color image by pressing a key on an operation panel (not shown) provided on the main body of the image forming apparatus 20. It may be performed. The switching of each fixing mode relating to the resolution of the toner image may be automatically performed by the control unit in accordance with the document information of the toner image to be formed, similarly to the switching relating to the type of the toner, or the operator may be set to 600 dpi. Or an image of 1200 dpi may be formed by selecting by pressing a key.

In this embodiment, the switching of each fixing mode relating to the type of the sheet medium is performed by a well-known means until the sheet medium reaches the fixing device 1 by a known means. Is automatically determined as to whether the sheet is a special sheet. Alternatively, the special sheet may be determined when a specific sheet feeding tray is used. The operator can select a desired mode by pressing a key on an operation panel (not shown) provided on the main body side of the printer 20. By designating whether or not to use the sheet, the control means (not shown) automatically determines whether the sheet-shaped medium stored in the sheet cassette is plain paper or a special sheet, and the mode is changed accordingly. It is also possible to make is switched. If the sheet medium is an OHP sheet among the special sheets, the control means is informed that the sheet medium is an OHP sheet in order to reduce the energizing time to the solenoid 63 to half the normal time.

If the fixing mode (T ₂ ) after the switching is higher than the fixing temperature (T ₁ ) before the switching, the heater 6 is energized, and the thermistor 8 is switched to the T _2. Is detected, the driving of the fixing belt 2 is started and pre-rotation is performed, and the thermistor 8 again
After detecting the number ₂ , the conveyance of the sheet-like medium by the fixing belt 2 can be started. By performing this pre-rotation, the entire fixing belt 2 can be efficiently heated. When the fixing mode is switched and the fixing temperature (T ₂ ) after the switching is lower than the fixing temperature (T ₁ ) before the switching, the power supply to the heater 6 is stopped and the driving of the fixing belt 2 is started. Start and pre-rotate,
After the thermistor 8 detects T ₂ again, the fixing belt 2
The conveyance of the sheet-like medium can be started. By performing this pre-rotation, the fixing belt 2
And the temperature of the fixing belt 2 can be efficiently reduced. Fixing belt 2 during pre-rotation
Is set to 125 mm / s, which is common to that at the time of fixing.

Here, the pre-rotation time required when switching from one fixing mode to another fixing mode is T ₁ and T ₂
It is known from the relationship with that that it is substantially constant. Therefore, the pre-rotation is performed for a time determined in accordance with the fixing mode before and after the switching, that is, for a time determined from the relationship between T ₁ and T _2, and after the elapse of this time, the fixing belt 2 rotates the sheet-like medium. The transport can be started. The fixing temperature is 150 ° C. and the fixing temperature is 160 ° C.
In the case of switching between the pre-rotation and the pre-rotation, since the temperature difference is relatively small, the pre-rotation is not performed. The heat dissipation is less efficient than the heating by the heater 6, T _1> it is pre-rotation time when a T ₁ <T ₂ than when it is T ₂ are the shorter.

Controlling the fixing temperature at any of the three temperatures, controlling the transport speed at any of the three speeds,
Controlling the pre-rotation time by any of the four times
This is for simplifying the control, and the control may be performed according to different fixing temperatures, transport speeds, and pre-rotation times according to the respective fixing modes. Further, the fixing mode does not need to be determined according to all of the type of toner, the resolution of the toner image, and the type of sheet medium, and may be determined by a combination of some of these parameters. Of the set temperature and the conveying speed of the sheet-shaped medium, only one of them may be controlled.

According to this embodiment, when the power of the image forming apparatus 20 is turned on, the power supply to the heater 6 and the pre-rotation are performed based on the temperature detection of the thermistor 8.
The state in which good fixing can be performed is completed, and the start-up is completed, and a state in which image formation and fixing can be performed. When the fixing mode is switched, the power supply to the heater 6 is switched, a predetermined pre-rotation is performed, the start-up is completed, and a state in which image formation and fixing can be performed. Image forming apparatus 20
If the release agent supply unit 50 has been replaced with a new one after power-on or after the previous image formation, the release agent supply unit 50 was replaced with a new one during the preheating. Is detected. When the operator performs a well-known operation for starting image formation, the photosensitive drum 25Y is charged by the charging device as the photosensitive member 25Y rotates in the direction A, and the electrostatic latent image corresponding to the original image is exposed by the exposure light 29Y. An image is formed, and this electrostatic latent image is developed by a developing device.

The sheet-like medium fed from the paper feed cassette 23 or 24 by the pickup roller 41 or 42 is further transported by the transport roller 43, reaches the registration roller 30 via the roller structure 44, and controls the image forming timing by the registration roller 30. Transfer device 22
Sent to. The toner image formed on the photoconductor 25Y is transferred onto the sheet-like medium conveyed in the direction of arrow B on the transfer device 22, and the toner remaining on the photoconductor 25Y after the transfer is scraped off by the cleaning device. Thus, the photoconductor 25Y is cleaned, and is subjected to the next charging.

The sheet medium to which the yellow toner has been transferred is conveyed in the direction of arrow B by the transfer device 22,
Magenta, cyan, and black toners are sequentially transferred as appropriate by the image forming apparatuses 21M, 21C, and 21BK that perform the same image forming step as the above image forming step in the image forming apparatus 21Y, and all the toners necessary for image formation are removed. After the image is transferred, the image is transferred from the transfer device 22 to the guide entrance 12 and guided by the entrance guide 12 to the fixing area. When a predetermined time elapses after the sheet-shaped medium is sent out from the registration roller 30, the standby time, the number of continuous sheets to be passed, the type of the sheet-shaped medium, and the time determined according to the number of sheets fixed by the release agent supply unit 50 are used. When the solenoid 63 is energized, an appropriate amount of the release agent is supplied to the application roller 32, and the release agent supplied to the application roller 32 is transferred to the fixing belt 2 as the fixing belt 2 rotates. Then, an appropriate amount of the release agent is applied to the fixing belt 2 without unevenness.

The sheet-like medium is conveyed by the movement of the fixing belt 2 whose moving speed is controlled in the fixing mode, and is conveyed to the first fixing section 15 and the second fixing section 16 which is continuous with the first fixing section 15. At a temperature controlled by the fixing mode, the toner is heated and pressurized to be fused and fixed. Specifically, the sheet-shaped medium is used as the first fixing unit 15.
When passing through the fixing belt 2, the toner given heat from the fixing belt 2 gradually melts and is assumed to be attached to the surface of the sheet-shaped medium. The toner is completely fixed on the sheet medium by the pressing force. Since an appropriate amount of the release agent is applied to the fixing belt 2, the releasability of the sheet medium and the toner is kept good.

Since the material, degree of foaming, hardness and the like of the elastic layer 10 are set as described above, not only one sheet is fixed but also
Even in the case where continuous fixing is performed, the heating by the heater 7 supplies heat to such an extent that hot offset does not occur, good fixing is performed, and it is necessary to interrupt fixing and perform reheating. Absent. Since the set temperature at the time of fixing and the conveyance speed of the sheet-shaped medium are controlled in accordance with each mode, good fixing is performed, and the sheet-like medium after fixing is passed through the conveyance roller 43 and the discharge roller 45 to the opening 46. Is discharged out of the image forming apparatus 20 and stacked on the paper discharge tray 27.

As described above, according to the belt fixing device, since the length of the fixing area is sufficiently long, excellent fixing is performed.
In particular, when fixing an OHP sheet, a sufficiently large amount of fixing heat can be supplied within a range that does not cause a decrease in fixing quality such as hot offset, so that the OHP sheet surface is smoothed, irregular reflection is suppressed, and gloss is reduced. That is, the HEIZ degree is improved. Absorption of transmitted light inside the toner,
Since scattering is suppressed, good image formation can be performed.

Although the fixing device to which the present invention is applied and the image forming apparatus provided with the fixing device have been described, the heater may be provided only in the heating roller among the heating roller and the pressing roller. The thickness and material of the fixing belt, the diameter, the thickness, and the material of the heating roller and the pressure roller can be appropriately combined. If the heating roller and the pressure roller have a low heat capacity and can perform satisfactory fixing, the fixing unit is configured to include only a portion where the fixing roller and the pressure roller are pressed against each other via the fixing belt. It can also be. Although the image forming apparatus of the present embodiment can form a color image and can form a single-color image, the image forming apparatus may form only a single-color image.

In the above embodiment, only the fixing belt 2 is described as a sheet conveying member provided with a release agent applying member. However, the pressing roller 5 also fixes a toner image while conveying a sheet-like medium. Therefore, the pressing roller 5 may be used as a sheet conveying member and a release agent applying member may be provided together with or instead of the fixing belt 2.

In the above embodiment, a belt fixing device is described as a fixing device to which the present invention is applied. However, the present invention can be applied to a heat roller pair type fixing device shown in FIG. The fixing device 72 includes a heating roller 73 for heating and conveying the sheet-like medium on which the toner image is fixed, and a pressing roller 5 pressed against the heating roller 73.
And The heating roller 73 and the pressure roller 5 form a sheet conveying member, and the heating roller 73 is provided with a flow roller 32 as a release agent applying member. Reference numeral 74 denotes a heater disposed in the heating roller 59. The heater 74 heats the heating roller 73 from the inside to heat the heating roller 73 and heat the sheet-like medium. . The symbol K indicates the rotation direction of the heating roller 73.

The same members as those in the above embodiment are denoted by the same reference numerals or are not shown. As illustrations omitted, for example, the casing 33, the entrance guide 12,
As in the case of the handle 37 and the heating roller 3, there are a heater 8, a contact / separation mechanism 57, and the like provided for the heating roller 73. In the fixing device 72, only the heating roller 73 is used as the sheet conveying member, and the application roller 32 is disposed on the heating roller 73. However, the heating roller 73 and the pressing roller 5, or only the pressing roller 5 is used as the sheet conveying member and the applying roller is used. 3
2 may be provided.

When the supply member 52 does not directly supply the release agent to the application roller 32 but supplies the release agent to the application roller 32 via an intermediate member, for example, an intermediate roller, the intermediate roller and the intermediate roller The application roller corresponds to a release agent application member, and the release agent is supplied to the intermediate roller by a supply unit that is brought into contact with and separated by the contact / separation mechanism. That is, in the present invention, the release agent applying member refers to an entire member to which the release agent is applied by the supply member and which applies the release agent to the sheet conveying member.

The release agent supply unit may have at least a tank of a supply member and a tank, and may be detachable from a fixing device separately from the supply member. The contact / separation mechanism is not limited to the one in the above-described embodiment, and various other mechanisms can be employed, such as the swing member 61 swinging using a motor having an eccentric cam instead of the solenoid. In this embodiment, only when the special sheet is the OHP sheet, the release agent application time is shortened as compared with other sheet-like media. However, the release agent application time is shortened for all the special sheets as compared with plain paper. You may. Since the release agent application time is adjusted in accordance with the release agent absorbency of the sheet-shaped medium, for a sheet-shaped medium having a low release agent absorbency, various ratios are used in accordance with the degree of the absorbability. This time can be shortened, and the time required for the sheet-like medium having high release agent absorbency can be increased at various ratios depending on the degree of absorbability.

The start time of the standby time may be discharge of the last sheet or the like instead of stopping the drive system in the image forming apparatus. The end timing of the standby time may be the start of driving of the drive system of the image forming apparatus or the fixing device instead of the image forming start operation. The determination as to whether or not continuous paper feeding is performed is not limited to whether the time until the next image forming start operation after discharging the last sheet is within 30 seconds, and another time may be used as the threshold. Alternatively, only the initially set number of image forming sheets may be determined as the number of continuous sheets. The contact start timing of the contact member may be, for example, not when a predetermined time has elapsed since the registration roller sent out the sheet medium, but when the registration roller has sent out the sheet medium, or when preheating has ended. The consumption amount of the release agent is not indirectly detected by the number of fixed sheets, but a sensor for detecting the amount of the release agent may be provided in the tank, or the supply member is brought into contact with the release agent application member. The detection may be performed based on the total time.

[0080]

According to the present invention, a release agent applying member for applying a release agent to a sheet conveying member for fixing a toner image while conveying a sheet medium, and a release agent applying member for the release agent applying member. A fixing member having a supply member for supplying a molding agent,
Since the supply member has a contact / separation mechanism for contacting / separating the release agent applying member, the supply agent is adjusted to control the supply amount of the release agent to the release agent applying member by bringing the supply member into contact with / separating from the release agent applying member. Further, it is possible to provide a fixing device that can maintain the supply amount of the release agent to the sheet conveying member at an amount suitable for fixing and can perform favorable fixing.

If the contact time of the supply member with respect to the release agent applying member by the contact / separation mechanism is made variable according to the standby time,
Regardless of the standby time, the release agent supply amount to the release agent application member is adjusted to an appropriate amount, and the release agent supply amount to the sheet conveying member can be maintained at an amount suitable for fixing, and good fixing is achieved. A fixing device capable of performing the fixing can be provided.

Assuming that the contact time is shorter as the standby time is longer, if the standby time is longer and the release agent is sufficiently impregnated in the supply member, the supply member is applied to the release agent application member for a shorter time. When the standby time is short and the release agent is not sufficiently impregnated into the supply member, the supply member is brought into contact with the release agent application member for a long time to supply the release agent to the release agent application member. By adjusting the amount to an appropriate amount, the supply amount of the release agent to the sheet conveying member can be maintained at an amount suitable for fixing, and a fixing device capable of performing satisfactory fixing can be provided.

If the contact time of the supply member with respect to the release agent applying member by the contact / separation mechanism is made variable according to the number of continuous sheets passed, the release agent applied to the release agent application member regardless of the number of continuous sheets passed. It is possible to provide a fixing device capable of adjusting the supply amount to an appropriate amount, maintaining the amount of the release agent on the sheet conveying member at an amount suitable for fixing, and performing good fixing.

If it is assumed that the contact time is longer as the number of continuous sheets passed is large, the number of continuous sheets passed is large and the release agent on the sheet transport member is consumed quickly, so that the release agent from the release agent application member to the sheet transport member can be consumed. When the transfer of the release agent is fast, the supply member is brought into contact with the release agent application member for a long time, and even if the number of continuous paper sheets is small and the release agent supply amount to the release agent application member is small, the supply member may be transferred to the sheet conveying member. When the supply of the release agent is sufficient, the supply member is brought into contact with the release agent application member for a short time, so that the amount of the release agent supplied to the release agent application member is adjusted to an appropriate amount, and It is possible to provide a fixing device capable of maintaining the supply amount of the release agent at an amount suitable for fixing and performing good fixing.

If the contact time of the supply member with respect to the release agent applying member by the contact / separation mechanism is made variable according to the type of the sheet medium, the release time to the release agent applying member is independent of the type of the sheet medium. It is possible to provide a fixing device capable of adjusting the supply amount of the mold agent to an appropriate amount, keeping the amount of the release agent on the sheet conveying member at an amount suitable for fixing, and performing good fixing.

Assuming that the contact time is shorter when the type of the sheet medium is the special sheet than when the sheet is the plain paper, if the sheet medium is the special sheet and the consumption of the release agent is small. When the amount of release agent supplied to the sheet conveying member is sufficient even if the amount of release agent supplied to the release agent application member is smaller than that of plain paper, the supply member is shorter than that of plain paper for the release agent application member. When the sheet-shaped medium is plain paper and the consumption of the release agent on the sheet conveying member is faster than the special sheet, and the transfer of the release agent from the release agent applying member to the sheet conveying member is faster, By contacting the supply member with the release agent application member for a longer time than the special sheet, the release agent supply amount to the release agent application member is adjusted to an appropriate amount, and the release agent on the sheet conveying member is adjusted. The supply amount can be maintained at an amount suitable for fixing, and good fixing can be performed. It is possible to provide a wearing device.

A supply member and a release agent storage tank for supplying the release agent to the supply member, including at least a release agent storage tank and a release agent supply unit detachable from the fixing device main body; The maintenance of the release agent supply unit is good, and when the release agent in the release agent storage tank is consumed and exhausted, it can be replaced with a new release agent supply unit quickly. A fixing device capable of performing supply can be provided.

The release agent supply unit has new detection means for detecting that the release agent supply unit is new, and the new detection means detects the contact time of the supply member with the release agent application member by the contact / separation mechanism. Supply of the release agent to the release agent application member according to the amount of the release agent in the release agent storage tank if it is made variable in accordance with the amount of release agent consumed after detecting that the release agent is new. By adjusting the amount to an appropriate amount, the supply amount of the release agent to the sheet conveying member can be maintained at an amount suitable for fixing, and a fixing device capable of performing satisfactory fixing can be provided.

Assuming that the contact time is longer as the consumption of the release agent is larger, the number of sheets fixed after the replacement of the release agent supply unit is large, and the release agent in the release agent storage tank is consumed. When the supply member is not sufficiently supplied to the supply member, the supply member is brought into contact with the release agent application member for a long time, and the number of fixed images after the replacement of the release agent supply unit is small. When the amount of release agent is large enough to be supplied to the supply member, the supply member is brought into contact with the release agent application member for a short time so that the amount of release agent supplied to the release agent application member can be adjusted appropriately. It is possible to provide a fixing device capable of adjusting the supply amount of the release agent to the sheet conveying member at an amount suitable for fixing and performing satisfactory fixing.

If the new detecting means includes a fusing member provided in the release agent supply unit and fusing by the ambient temperature in the fixing device main body, and a detecting means for detecting the non-fusing state of the fusing member, By utilizing the temperature rise in the fixing device main body, it is possible to provide a fixing device that can reliably detect replacement of the release agent supply unit with a relatively simple configuration.

An endless fixing belt for conveying a sheet-like medium on which the toner image is fixed, a heating roller and a fixing roller around which the fixing belt is wound, and a fixing roller are disposed opposite to the fixing roller via the fixing belt. If the sheet conveying member is a fixing belt and / or a pressure roller, it is possible to provide a belt-type fixing device having the above-described effects.

A heating roller for heating and transporting the sheet-like medium on which the toner image is fixed and a pressure roller pressed against the heating roller are provided, and the sheet transporting member includes a heating roller and / or a pressure roller. If it is a roller, it is possible to provide a heat roller pair type fixing device having the above-described effects.

Since the present invention resides in an image forming apparatus having such a fixing device, a high-quality image can be formed, and an image forming apparatus with high user reliability can be provided.

[Brief description of the drawings]

FIG. 1 is a side view schematically illustrating a fixing device to which the present invention is applied and an image forming apparatus including the fixing device.

FIG. 2 is a side sectional view of the fixing device shown in FIG.

FIG. 3 is a side view showing a contact / separation mechanism.

FIG. 4 is a control table relating to release agent application by a supply member to the release agent application member.

FIG. 5 is a cross-sectional view showing a main part of a heat roller pair type fixing device to which the present invention is applied.

[Explanation of symbols]

 1, 72 fixing device 2 fixing belt as sheet conveying member 3 heating roller 4 fixing roller 5 pressure roller 20 image forming device 32 release agent application member 50 release agent supply unit 51 release agent storage tank 52 supply member 54 fusing Member 56 Detection means 57 Contact / separation mechanism 73 Heating roller as sheet conveying member

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideo Furukawa 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Inventor Hiroshi Yoshinaga 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Takanari Saito 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H033 AA09 AA42 AA45 BA45 BA46 CA02 CA09 CA16 CA17 CA30

Claims (14)

[Claims] A release agent applying member for applying a release agent to a sheet conveying member for fixing a toner image while conveying a sheet-like medium, and a supply for supplying the release agent to the release agent applying member A fixing device having a contact / separation mechanism for contacting / separating the supply member with / from the release agent applying member. 2. A fixing device according to claim 1, wherein a contact time of said supply member with said release agent applying member by said contact / separation mechanism is variable according to a standby time. . 3. The fixing device according to claim 2, wherein the contact time is shorter as the standby time is longer. 4. The fixing device according to claim 1, wherein a contact time of the supply member with respect to the release agent applying member by the contact / separation mechanism is determined in accordance with a continuous number of sheets passed. A fixing device characterized by being variable. 5. The fixing device according to claim 4, wherein the contact time is longer as the number of continuous sheets passed is larger. 6. The fixing device according to claim 1, wherein a contact time of the supply member with respect to the release agent applying member by the contact / separation mechanism is determined in accordance with a type of the sheet medium. A fixing device characterized by being variable. 7. The fixing device according to claim 6, wherein the contact time is shorter when the type of the sheet medium is a special sheet than when the sheet is a plain paper. . 8. The fixing device according to claim 1, wherein at least the release agent is stored in the supply member and a release agent storage tank that supplies the release agent to the supply member. A fixing device comprising a tank and a release agent supply unit detachable from the fixing device main body. 9. The fixing device according to claim 8, further comprising a new detecting means for detecting that the release agent supply unit is new, wherein the supply member is provided to the release agent application member by the contact / separation mechanism. Wherein the contact time of the fixing device is made variable in accordance with the consumption of the release agent after the new detection unit detects that the release agent supply unit is new. 10. The fixing device according to claim 9, wherein the contact time is longer as the consumption amount is larger. 11. A fixing device according to claim 9, wherein said new detecting means is provided in said release agent supply unit and is adapted to be blown off by an ambient temperature in a fixing device main body, and a non-fusing member of said fusing member is provided. A fixing unit for detecting a fusing state. 12. The fixing device according to claim 1, wherein the fixing belt is wound around an endless fixing belt for conveying a sheet-like medium on which a toner image is fixed. A heating roller, a fixing roller, and a pressure roller disposed to face the fixing roller via the fixing belt, wherein the sheet conveying member is the fixing belt and / or the pressure roller. Characteristic fixing device. 13. A fixing device according to claim 1, wherein a heating roller for heating and transporting a sheet-like medium on which a toner image is fixed is pressed against said heating roller. And a pressure roller, wherein the sheet conveying member is the heating roller and / or the pressure roller. 14. An image forming apparatus comprising the fixing device according to claim 1.