JPH02134665A - Image forming device - Google Patents

Abstract

PURPOSE:To minimize the calorific capacity of a heating body by traveling a recording material that fixes a picture at a constant speed so as to bed in close contact with a fixing film and permitting the heating body to heat and melt a toner picture through the fixing film. CONSTITUTION:A transfer sheet P carried to a fixing device 20 along a guide 10 from a transfer part 8 and carried with an unfixed toner picture Ta enters between the fixing sheet 40 of a press-contact part N of the heating body 21 with a press roller 22 and the press roller 22. The face of the unfixed toner picture passes by a mutual press-contact part N at the speed the same as the carrying speed of the sheet P, receiving pinching force, while the face is overlapped with the back of the turning fixing film 40 in the same direction. Consequently, the heating body 21 heats and melts the toner picture made of heat melting toner on the sheet P through the fixing film 40, and its surface is completely softened and melted. Thus, the calorific capacity of the heating body can be minimized without developing fixing defect and offset.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming bag for copying machines, laser beam printers, facsimile Φ microfilm league printers, image display devices, recording machines, and the like.

More specifically, electrophotography - Recording material (electrofax) - Electrostatic recording sheet/transfer material sheet using a toner made of heat-meltable resin etc. by an appropriate image forming process means such as electrostatic recording or magnetic recording.・Direct method on the surface of printing paper, etc.) or! An unfixed toner image corresponding to the target image information is formed and carried using the 11-contact (transfer) method, and the unfixed toner image is heat-fixed as a permanent fixed image on the surface of the recording material carrying the image. The present invention relates to an image forming apparatus that uses

(Prior Art) Conventionally, a fixing device used in this type of device uses a heating roller maintained at a predetermined temperature and a pressure roller having an elastic layer and in pressure contact with the heating roller. A roller fixing method is often used in which a recording material on which a toner image has been formed is heated while being nipped and conveyed.

(Problems to be Solved by the Invention) However, in this type of device, in order to prevent the so-called offset phenomenon in which toner is transferred to the heating roller,
It is necessary to maintain the heating roller at an optimal temperature, and the heat capacity of the heating roller or heating element must be increased. That is, when the heat capacity of the heating roller is small, the temperature of the heating roller tends to fluctuate greatly toward a lower temperature side or a higher temperature side due to paper passing or other external factors due to the relationship with the amount of heat supplied by the heating element. If the temperature changes to the low temperature side,
Insufficient softening and melting of the toner causes fixing failure and low-temperature offset, and when the temperature changes to the high temperature side, the toner is completely melted and the cohesive force of the toner decreases, resulting in high-temperature offset.

In order to avoid this problem, increasing the heat capacity of the heating roller increases the time it takes to heat the heating roller to a predetermined temperature, causing another problem of increasing standby time when using the device. .

The present invention solves the problems of the conventional apparatus described above, and makes it possible to reduce the heat capacity of the heating element without causing fixing failure or offset. As a result, standby time, power consumption, and It is an object of the present invention to provide an image forming apparatus that causes a small temperature rise inside the machine and has other remarkable features.

(Means for solving problems) The present invention is.

An image forming means for forming an unfixed toner image corresponding to target image information by carrying toner made of a heat-melting resin or the like on the surface of a recording material; a fixing film; a means for driving the fixing film; A heating body is placed on one side of the fixing film with the fixing film inside, and a heating body is placed on the other side, and the unfixed toner image bearing side of the recording material is brought into close contact with the heating body through the fixing film. between the fixing film and the pressure member, which is driven to run in the same direction at the same speed as the conveyance speed of the recording material carrying the unfixed toner image conveyed from the image forming means side. a toner image heat fixing unit that heats and fixes the unfixed toner image on the surface of the recording material by introducing the recording material into the recording material, and a jam detection unit that detects the occurrence of a jam in the recording material conveyed through the recording material conveyance path of the apparatus. Even if a tensile external force is applied to the fixing film which has stopped running due to an emergency stop of the device operation based on the jam detection signal of the jam detecting means, the fixing film resists the tensile external force. The gist of the present invention is an image forming apparatus comprising: means for preventing movement of a film;

(Function) (1) The recording material to which the image is to be fixed is introduced between the fixing film and the pressure member, which are running in the same direction at the same speed as the recording material conveyance direction, and the unfixed toner remains on the fixing film surface. When the image bearing side surface is in close contact with the fixing film and overlapped with the fixing film, the mutual pressure contact portion of the heating body and the pressure member is subjected to a squeezing force, and the surfaces become misaligned or wrinkled due to the speed difference between them. They overlap and pass through in close contact with each other.

■Heating process During this process of passing through the mutual contact area, the unfixed toner image on the recording material surface is heated and softened and melted by the heating body through the fixing film, and in particular, the surface layer is completely softened and melted, exceeding the toner melting point. do. In this case, the heating body, fixing film, toner image, and recording material are well compressed and adhered to each other by the pressure member at the mutual pressure contact portion of the heating body and the pressure member, and heat is transferred effectively, so that the heat can be heated for a short time. The toner is sufficiently softened and melted to provide good fixing properties.

On the other hand, the temperature rise of the recording material itself is actually extremely small and there is little waste of thermal energy.In other words, the recording material itself is not heated, and only the toner is effectively heated to soften and melt, thereby heating the toner image with low power. Fixation can be performed well.

Here, a note will be made regarding the softening and melting of the toner described in the present invention. The temperature conveniently expressed as the toner's "melting point" refers to the minimum temperature required for the toner to fix. In some cases, the viscosity decreases to such an extent. Therefore, even when the toner is conveniently expressed as melting during fixing, it may actually indicate a decrease in viscosity to the extent of softening.The present invention also includes such cases; Even when it is conveniently expressed as "fixed," depending on the toner, it may be more appropriate to say "high viscosity" rather than "solidification." The present invention also includes such cases.

■Cooling process The toner image that is in close contact with the fixing film surface and sequentially passes through the mutual pressure contact area of the heating body and the pressure member.The recording material portion that has been softened and melted by heating is kept in close contact with the fixing film surface even after passing through the pressure contact area. The conveyance is continued for a while, and this period is used as a cooling process, in which the heat of the toner softened and melted in the heating process is radiated to cool and fix the toner. Due to this cooling and solidification, the cohesive force of the toner becomes extremely large, causing it to behave as a group, and while the adhesion and adhesion force to the recording material side increases, the cohesive force to the fixing film side decreases significantly. When the toner is heated and softened and melted in the heating process, it is pressurized by the pressure member, so at least a part of the toner image penetrates into the surface layer of the recording material, and the amount of the toner image that penetrates is solidified by cooling. The anchor effect increases the adhesion and adhesion of the cooled and solidified toner to the recording material side.

(2) Separation process After the toner image is cooled and solidified in the above cooling process, the recording material is sequentially separated from the fixing film surface. At the time of this separation, the toner image is cooled and solidified and has a sufficiently large adhesion/fixing force to the recording material, but the adhesion/fixing force to the fixing film is extremely small, so the portion of the recording material where the image has been fixed generates toner offset with respect to the fixing film. They are easily separated one after another without any problems.

In this way, the recording material on which the image is to be fixed is made to run in close contact with the fixing film at the same speed so that the unfixed toner image bearing surface faces the running fixing film surface, and the toner image is heated and melted by a heating body through the fixing film. In addition, since the recording material and the fixing film are separated after the toner image is cooled and fixed, toner offset with respect to the fixing film does not occur, and a heating element with a small heat capacity is used, and power is supplied to the heating element. This can be done with a simple configuration, and by maintaining the heating element at a temperature sufficiently high compared to the temperature (melting point or softening point) at which the toner should be heated for fixing, the toner image can be improved efficiently. The rotational heating allows for sufficiently good fixing without defective fixing with less energy, resulting in an image forming device that requires less standby time when the device is in use, consumes less power, and has less internal temperature rise. This effect is achieved.

(2) Normal image type 1 & devices use a jam detection signal when a so-called jam trouble occurs in which the recording material fed to the recording material conveyance path (sheet path) in the device is not conveyed correctly due to a paper jam, etc. It is configured to automatically stop the device drive in an emergency. Then, the jammed recording material is removed and the device is restarted.

In this case, if the recording material is sandwiched between the heating body and the pressure member of the fixing means and the loading drive is stopped, the mutual pressure contact between the heating body and the pressure member is released by operating the release means. After that, the recording material is removed.
Device users often forget to release the pressure and forcefully pull the recording material sandwiched between the heating element and the pressure member to resist the mutual pressing force between the heating element and the pressure member. In many cases, they were pulled out and removed.

In the case of the fixing means of the present invention, in which a fixing film is interposed between the heating body and the pressure member, and the toner image on the recording material is heated and fixed via this fixing film, the heating body and If the sandwiched recording material is forcibly pulled and removed without releasing the mutual pressure contact with the pressure member, the fixing film sandwiched together with the recording material will be dragged along with the recording material due to the frictional force. When the recording material is pulled out diagonally, the fixing film moves diagonally and becomes a wavy surface, and this wavy film is dragged by the heating body as the recording material is pulled out. When the film enters the pressure contact area between the film and the pressure member, it is crushed by the pressure, resulting in local double-fold wrinkles on the film surface.

Since such wrinkles are plastic deformation of the film itself, they will not return to normal and disappear after that, and the wrinkles and the surface area of the film other than the wrinkles will be affected by heat conduction and pressure during heat fixing by the heating body and pressure member. Non-uniformity occurs in the longitudinal direction of the pressure contact portion, which results in uneven fixing of the image on the recording material, leading to the need to replace the fixing film.

In the present invention, even if a tensile external force is applied to the fixing film which has stopped running due to an emergency stop of the device operation based on the jam detection signal of the jam detecting means, the apparatus can resist the tensile external force. Since the fixing film is equipped with a means for preventing movement of the fixing film, it is possible to prevent the recording material, which is caught between the heating body and the pressure member together with the fixing film, from being squeezed between them by forgetting to release the mutual pressure contact between the heating body and the pressure member when handling a jam. Even if the fixing film is pulled out and removed, the fixing film is in a state where it is prevented from moving, so it will not be dragged and moved by the frictional force with the recording material, and only the recording material will be in contact with the pressure part between the heating body and the pressure member. The fixing film slides between the surface of the fixing film and the pressure member and is pulled out.

Therefore, it is strictly possible to prevent the fixing film from becoming corrugated and being bent and moved along with the pulled-out recording material to the pressure contact portion between the heating body and the pressure member, thereby causing wrinkles and damage.

(Example) <Example 1> (Figs. 1 to 3) The apparatus of this example is an electrophotographic copying apparatus of a reciprocating document table type and a rotary drum type fist transfer type.

(1) Overall schematic configuration of the equipment (Fig. 1) In Fig. 1, lOO is the equipment housing, and l is a reciprocating member made of a transparent plate member such as a glass plate disposed on the top plate 100a of the equipment housing. It is a movable original cutting table, and the upper surface plate 100a of the machine case is placed on the right side a in the drawing.
, are driven to reciprocate in the left direction a at predetermined speeds.

G is a document, which is placed on the top surface of the document cutting table 1 according to a predetermined placement standard with the image side to be copied facing downward, and is set by placing the document pressure bonding plate 1a over it and pressing it down. .

1OOb is the top plate 10 of the machine housing, and the original ai is on the Oa side. ! i
A slit opening serving as a document illumination section is opened with the longitudinal direction perpendicular to the reciprocating direction of the table 1 (direction perpendicular to the paper surface). As for the number of originals, the downward image surface of the original G set on device A on table L passes through the position of the slit opening toob sequentially from the right side to the left side during the forward movement of document mounting table L to the right side a. In the process of passing, the light Ll of the lamp 7 passes through the slit opening 100b and the transparent original aδ.
The illumination is scanned through the platform l. The illumination scanning light reflected from the document surface is imaged and exposed on the surface of the photosensitive drum 3 by the short focus and small diameter imaging element array 2.

The photosensitive drum 3 is coated with a photosensitive layer 3a such as a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer, and is driven to rotate clockwise as shown by an arrow around a central support shaft 3b at a predetermined circumferential speed. The charged surface of the photosensitive drum 3 is subjected to image-forming exposure (slit exposure) by being subjected to a positive or negative charging process by the charger 4, and subjected to image-forming exposure (slit exposure) of the original image on the charged surface thereof. Electrostatic latent images corresponding to the original image are sequentially formed.

This electrostatic latent image is sequentially visualized by a developing device 5 using toner made of a resin or the like that softens and melts when heated, and the developed toner image is transferred to a location where a transfer discharger 8 is provided as a transfer section. I will do it.

S is a cassette loaded with transfer material P as a recording material, and the sheets in the cassette are fed one by one by the rotation of the feeding roller 6.

Next, by the registration rollers 9, when the leading edge of the toner image forming portion on the drum 3 reaches the transfer discharger 8, the leading edge of the transfer material sheet P also reaches the open position between the transfer discharger 8 and the photosensitive drum 3. The timing is adjusted so that the two match, and the two are fed synchronously. Then, the toner image on the photosensitive drum 3 side is sequentially transferred onto the surface of the fed sheet by the transfer discharger 8.

The sheet to which the toner image has been transferred in the transfer section is sequentially separated from the three surfaces of the photosensitive drum by a separating means (not shown), and guided by a conveyance guide 10 to a fixing device 20, which will be described later, to heat the unfixed toner image carried thereon. After undergoing a fixing process, the image is discharged onto a paper discharge tray 11 outside the machine as an image formed product (copy).

On the other hand, the surface of the photosensitive drum 3 after the toner image has been transferred is subjected to removal of adhered contaminants such as residual toner by a cleaning device ff112, and electricity is removed by the fog light L2 on the entire surface, and electrical residual memory is erased and the edges are removed. It is then used for image formation.

PH1 is a paper feed detection sensor (for example, a photo sensor) disposed in the sheet path section between the feed roller 6 and the registration roller 9, and PH2 is a paper discharge detection sensor (for example, a photo sensor) disposed next to the fixing device 20. It is.

(2) Fixing device 2120 (FIGS. 2 and 3) FIG. 2 is an enlarged view of a portion of the fixing device in an image fixing state.

Reference numeral 40 designates an endless belt-like fixing film, which is stretched around a pair of left and right parallel turn rollers (take-up reroller and delivery roller) 41 and 421111.

Reference numeral 21 denotes a heating body disposed with its lower surface in contact with the upper surface (inner surface side) of the downward measuring film portion of the endless fixing film 40.

Reference numeral 22 denotes a pressure roller as a pressure member having an elastic layer made of silicone rubber or the like on a core material made of metal or the like, and is placed in a predetermined contact with the lower surface of the heating body with the film portion on the downward side of the fixing film 40 sandwiched therebetween. They are pressed against each other with contact pressure. That is, in this embodiment, the right end of both ends 22a of the pressure roller 22 is supported by bearings on a pressure lever 44 that can freely swing up and down about a support shaft 43, and the left end of the pressure lever 44 is supported by bearings. By constantly lifting and rotating the pressure roller 22 around the support shaft 43 by the lifting spring 45, the upper surface of the pressure roller 22 is attached to the lower surface of the heating body 21 with the fixing film 40 in between, for example, A4@
They are pressed against each other with a total pressure of 4 to 6 kg.

46 is a push button for releasing pressure, and when this button is pressed, the if pin 48 of the lever 47 is pushed, and the lever 47 rotates clockwise around the support shaft 49 as shown by the two-dot chain line. Due to the rotational force, the upper side of the left end of the pressure lever 44 receives a downward force from the second pin 50 of the lever 47, and due to the upward force, the pressure lever 44 resists the pull-up spring 45 around the support shaft 43. The pressure roller 22 is pushed down as shown by the two-dot chain line, and the pressure roller 22 is lowered below the heating body 21, so that the pressure roller 22 and the heating body 2
1, and the pressure welding is released. When the push button 46 is released, the original pressurized state is restored.

- When the button 46 is pressed sufficiently, the pressed state is locked and detented, so that even if the button is released, the pressure release state is maintained, and when the button is pressed again, the above lock is released and the original state is restored. It is also possible to use a push-chain structure that returns to the pressure-welded state.

The pressure roller 22 is connected to the heating body 21 with the fixing film 40 in between.
In the state IE in pressure contact with the lower surface of the sheet, a drive gear train (not shown) has the same circumferential speed as the transport speed of the transfer material sheet P that is transported from the image transfer section 8 to the fixing device 20 via the guide 10. It is rotated counterclockwise. As a result, a feeding force is applied to the portion of the fixing film sandwiched between the pressure roller 22 and the heating body 21, and the endless fixing film 40 is brought into close contact with the lower surface of the heating body 21 while the rollers 41, 4211. 1 is rotated clockwise at the same circumferential speed as the rotational circumferential speed of the heating roller 22.

In this case, an appropriate rotational load is applied to the roller 42,
This rotational load causes at least the roller 42 and the heating element 2 to
The part of the fixing film between the two parts always runs under tension. FIG. 3 shows a cross-sectional view of the rotational load mechanism for the roller 42. As shown in FIG.

That is, 42a is the rotation center axis on one end side of the roller 42,
The bearing is made to protrude outward from the side plate 51, and its protruding shaft portion 4
2b is the end of the cross-sectionally rectangular shaft. Reference numeral 2 denotes a bearing, which is a friction plate fixed substantially concentrically with the shaft 42a on the outer surface of the side plate 51; 53, a friction retainer fitted externally to freely slide in the axial direction on the protruding shaft portion 42b; and 55, a friction plate attached to the end of the protruding shaft portion 42b. A spring holder 54 is fitted and fixed to the outside, and 54 is the friction temporary holder 53 and the spring holder 5.
This is a spring compressed between 5 and 5. The friction temporary presser foot 53 is constantly pressed against and in contact with the friction plate 52 due to the pressing force of the spring 54, and the mutual frictional force between the two members 52-53 is applied to the roller 4.
Acts as a rotational load of 2.

Reference numeral 60 denotes fixing film movement blocking means. This means in this example includes a claw type 61 integrally provided concentrically on one end side of the roller 42.
It consists of a lever 62 that swings into and out of engagement with the pawl type 61, and an electromagnetic solenoid plunger 63 that swings the lever. Reference numeral 62a denotes a pivot axis of the lever 62, and reference numeral 62b denotes an engagement/disengagement wind for the pawl type 61, which is made Af+ on one arm of the lever 62. 63a is an electromagnetic solenoid plunger 63
The lower end of the plunger is connected to the other arm end of the lever 62 by a pin 63b.

The electromagnetic solenoid-plunger 63 is normally energized, so the plunger 63a hangs downward under its own weight, and in conjunction with this, the lever 62 is rotated counterclockwise, and the air 62b for engaging and disengaging the lever 62 is moved by the roller. It is held in the state shown by the solid line at a position that escapes outward from the claw mold 61 on the 42 side. When the electromagnetic solenoid is energized, the puncher 63a is pulled upward and the lever 62 is rotated clockwise as shown by the two-dot chain line.
2a is engaged with the claw mold 61, and the roller 42 is stopped from rotating. The endless fixing film 40 is driven 0 rotations and is repeatedly used to heat and fix the toner image, thereby improving heat resistance and release. Thin wall with excellent strength and durability (for example, several JL)
For example, a film made of PEA resin (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin) or PI resin (polyimide resin) is suitable as a fixing film. PFA resin is a synthetic resin based on tetrafluoroethylene, and has features such as being stable at high temperatures, having a small coefficient of friction, and being stable against chemicals. PI resin also has excellent heat resistance, chemical resistance, mechanical properties, and dimensional stability.

The heating element 21 has a width of 160 gm and a length (length in the direction perpendicular to the paper) of 2 on the lower surface of a base material made of a heat-resistant and electrically insulating base material such as alumina or a composite member containing the same.
It has a 16 mm linear or band-shaped heating section 28 made of, for example, TazN, and further has a sliding protective layer of, for example, Ta20s formed on its surface. The lower surface of the heating body 21 is smooth, and the front and rear ends are rounded to enable smooth sliding on the surface of the fixing film 40.

The heat generating portion 28 of the heating body 21 has a small heat capacity, and is energized in a pulsed manner by an energizing circuit (not shown), and its temperature is instantaneously raised to about 260 to 300''C each time.

Then, it is fixed along the guide 10 from the transfer section 8? c2t
Transported to 20. The transfer material sheet P carrying the unfixed toner image Ta enters between the fixing sheet 40 and the pressure roller 22 at the pressure contact portion N between the heating body 21 and the pressure roller 22, so that the unfixed toner image surface is transferred to the sheet. The heating body 21 is overlapped with the lower surface of the fixing film 40 (the lower surface of the descending film portion) which is rotating in the same direction at the same speed as the conveying speed of P.
The unfixed toner-image surface of the sheet P passes through the mutual pressure contact area N between the sheet P and the pressure roller 22 while being subjected to a clamping force, and the unfixed toner-image surface of the sheet P passes through the mutual pressure contact area N between the pressure roller 22 and the heating body 21 until it enters the mutual pressure contact area N.
The fixing film is kept in a non-contact state with the lower surface of the fixing film portion between the fixing film and the fixing film.

This process of passing through the mutual pressure bonding portion N is a heating process in which the toner image is heated to soften and melt as described in (1)-0 of (Operation).As described above, the heating process in this embodiment is as follows. A linear heating section 28 is provided in the heating body 21.
A heating element 2 configured to repeatedly generate heat by supplying electricity in a pulsed manner to the heat generating portion 28 having a low heat capacity and integrally formed with the heating element 28.
It is carried out by 1. That is, the toner image Ta on the sheet P transported at a predetermined transport speed is
-The fixing film 40 is conveyed without deviation according to the conveyance speed of P, and is sequentially fed into the effective width W of the linear heat generating part determined according to the width of the heat generating part 28 of the heating body 21 to be heated. As a result, a softened and melted image Tb is formed.

The sheet portion that has passed through the mutual pressure contact portion N between the heating body 21 and the pressure roller 22 is conveyed by the conveyance guide 32 while remaining in close contact with the lower surface of the fixing film 40 until it reaches the position of the drive roller 41. serves to support the back surface of the sheet P and maintain close contact with the fixing film 40.

This conveyance process is used as a cooling process in the above (action) (1)-
As described in item 0, the heat of the softened and melted toner Tb is naturally radiated, and the toner is cooled and solidified Tc. It is also possible to provide a configuration in which a radiation fin member or the like is provided to perform forced cooling.

When it reaches the position of the roller 41, the fixing film 4
0, the running direction of the fixing film 40 is turned away from the sheet 2 surface along the surface of the roller 41 with a large curvature.
and sheet P are separated from each other and ejected to the paper ejection tray 11. By the time of this separation, the toner has been sufficiently cooled and solidified, as described in (1)-0 of (Operation) above. Since the adhesion and adhesion force of the toner to the sheet P is sufficiently large and that to the fixing film 40 is extremely small, the fixing film 40 and the sheet P can be separated without substantially causing toner offset to the fixing film 40. Easily made sequentially.

In this embodiment, the temperature of the linear heat generating portion 28 of the heating body 21 is instantaneously raised to a high enough temperature relative to the melting point (or possible temperature) of the toner when energized, so there is no need to preheat the heating body. Yes, there is little heat transfer to the pressure roller 22 during non-fixing, and even during fixing, the fixing film, toner image, and sheet are interposed between the heating body 21 and the pressure roller 22, and the heat generation time is short. As a result of this, a sharp temperature gradient is generated, so that the pressure roller 22 is difficult to rise in temperature, and its temperature is maintained below the melting point of the toner even if continuous image formation is performed to the extent required for practical use.

In the apparatus of this embodiment having such a configuration, the toner image made of heat-tactile toner on the sheet P is first heated and melted by the heating body 21 via the fixing film 40, and in particular, the surface layer portion thereof is completely melted. to soften and melt. At this time, the heating body, fixing film, toner image,
The sheets are well bonded and provide efficient heat transfer. Thereby, the heating of the sheet P itself can be suppressed as much as possible, and the toner image can be efficiently heated and melted. In particular, by limiting the time for energization and heat generation, it is possible to save energy.

A small heating element is sufficient, so its heat capacity is small, and there is no need to heat up the heating element in advance, so power consumption during non-image formation can be reduced, and temperature rise inside the machine can also be prevented. .

In this embodiment, since the temperature of the pressure roller 22 is maintained lower than the melting point of the toner as described above, it is possible to promote heat dissipation of the toner image in the cooling process following the toner image heating process. . Therefore, the time required for cooling can be shortened, and the device can be downsized.

(3) In the case of jam trouble, as described above, the pressure roller 22 is moved to the heating body via the fixing film 40 by the clockwise rotational force of the pressure lever 44 by the pull-up spring 45, as shown by the solid line in FIG. 21
The electromagnetic solenoid-plunger 63 of the fixing film movement prevention means 60 is not energized, and the claw 61 integrated with the roller 42 is connected to the lever 62 to release the air. 62b is held in the escape position as shown by the two-dot chain line, and the fixing device 20 is maintained in a state where it can perform fixing processing.

On the other hand, even after a predetermined period of time has elapsed after the paper feed detection sensor PH1 (Fig. 1) detects that the feeding of the transfer material sheet P has started based on the image formation start signal, the paper ejection detection sensor PH2 fixes the image. When the ejection of a completed sheet is not detected, a control circuit (not shown) determines that there is an abnormality in conveyance of the transfer material sheet, that is, a so-called sheet jam has occurred, and the apparatus is immediately put into an emergency stop state, and the electromagnetic solenoid plunger 63 is activated. is energized, and the claw portion 62b of the lever 62 is engaged with the windmill 61 of the roller 42, as shown by the two-dot chain line. That is, the roller 42 is in a state where it is prevented from rotating.

When an emergency stop of the apparatus occurs due to a sheet jam as described above, the operator releases the pressure contact between the pressure roller 22 and the heating body 21 by pressing the pressure release push button 46 and releases the pressure contact part N. fixing film 40 and pressure roller 22
By releasing the jammed transfer material P held between them, the jammed transfer material sheet can be easily taken out and removed without any resistance or trouble.

After clearing the jam, the push button 46 is released, the pressure roller 22 is brought back into pressure contact with the heating element 21, and the control circuit is reset to turn off the current to the 'rrL magnetic solenoid pump 63. When it is cut off, the claw portion 62b moves away from the windmill 61, and the fixing device 20 returns to the fixing process ready state j6 again.

In the above jam removal procedure, the operator first presses the push button 46 to release the pressure roller 22 from the heating body 21 and removes the jammed transfer material. I forgot, heating element 21
In some cases, the jammed transfer material sheet sandwiched between the heating element 21 and the pressure roller 22 may be pulled out and removed by forcefully pulling it out against the mutual pressing force between the heating element 21 and the pressure roller 22. In this case, the jammed transfer material sheet is removed. As described above, the fixing film 40 is dragged and moved as the material sheet is pulled out, causing damage such as wrinkles to the fixing film 40.

In some cases, even if you forget to remove the pressure on the heating body 21 of the pressure roller 22 and forcefully pull out the jammed transfer material sheet that is sandwiched between the two members, the roller 42 Since the rotation of the fixing film 40 is stopped by the engagement of the lever claw portion 62b with the windmill 61, that is, the rotational movement of the fixing film 40 is prevented, the dragging movement of the fixing film 40 caused by pulling out the jammed transfer material sheet is prevented. The jammed transfer material sheet is pulled out from the pressure contact portion N without slipping on the surface of the fixing film whose movement is prevented. Therefore, as the fixing film 40 is dragged and moved as the jammed transfer material sheet is pulled out, the surface of the fixing film 40 is undulated, and the wavy surface advances to the pressure contact area N between the heating element 21 and the pressure roller 22, and is applied with the pressure. This prevents the occurrence of wrinkles on the surface of the fixing film 40 due to crushing.

<Example 2> (FIGS. 4 and 5) This example shows another example of the fixing film movement prevention means 60. Components and portions that are common to those in the example shown in FIGS. 2-3 are given the same reference numerals and repeated explanations will be omitted.

In this example, the spring presser 5 has a rotational load a4I on the roller 42.
The outer surface of 5 is provided with radially engaging grooves 55a,
A stop plate 64 is provided facing the outer surface of the spring holder 55 and is provided with radially engaging blades 64a that bite into the engagement grooves 55a, and can freely move forward and backward with respect to the spring holder 55. An electromagnetic solenoid for moving the plunger 64 forward and backward is connected to the stop plate 6 via the lever 65.
It is connected to 4. Reference numeral 65a is a rotation center axis of the lever 65, and one arm and the other arm of the lever 65 are connected to the stop plate 6, respectively.
4 forward/backward axis 64b and electromagnetic solenoid plunger 66
It is connected to the reciprocating plunger 66a by pin shafts 65b and 65c.

Normally, the power to the 'iua solenoid-plunger 66 is off, and the plunger 66a projects a predetermined length forward from the solenoid by a biasing member (not shown). As shown by the solid line in Fig. 5, the spring presser 5 is removed from the outer surface of the spring presser 55
The relationship with 5 has been severed.

When the device is brought to an emergency stop due to the detection of a sheet jam, at that point the 'rrL magnetic solenoid-plunger 66
The plunger 66a is held in a retracted state by the excitation of the solenoid, and in conjunction with this, the stop plate 64 is moved via the lever 65 to the position shown in FIG.
As shown by the dotted chain line, the roller 42 moves forward relative to the outer surface of the spring holder 55, and the engagement teeth 64a on the stop plate 64 side engage with the engagement groove 55a on the spring holder 55 side, so that the roller 42 is stopped from rotating.

Jam removal is carried out in the same manner as in Embodiment 1, and when the control circuit is reset after the jam removal, the power to the electromagnetic solenoid-plunger 66 is cut off, and the stop plate 64 escapes from the spring retainer 55, thereby removing the edge of both. is cut, that is, the rotation of the roller 42 is released, and the fixing device W120 returns to a state in which fixing processing is possible.

(Others) (1) The pressure release mechanism illustrated is a combination of a manual push button and a lever, but the mechanism is not limited to this. By releasing the pressure roller, a link-cam may be used to release the pressure roller from being pressed against the heating body.

(2) The pressure roller can be released from the heating body not only when a jam occurs, but also when necessary, such as when replacing the fixing film.

(3) The heating body side may be movable to release the pressure contact with the pressure roller.

(4) The fixing film is exemplified by PFA resin or PI resin, but it is not limited to these, of course, and has heat resistance higher than the fixing temperature, low coefficient of friction, toner resistance, dimensional stability, and toughness. Various other resin films (or sheets) having intermediate layer/composite layer configurations and films (or sheets) made of materials other than resin can be used.

(5) The fixing film is not limited to the endless type shown in the example, but may also be a belt-shaped film on the right end that is wound around the delivery shaft in a roll, and the film is wound by passing it between the heating body and the pressure member. To adopt a system in which the winding movement is controlled to the take-up shaft side and the film is sequentially subjected to fixing processing, and when almost all of the fixing film on the delivery shaft side is wound onto the take-up shaft side and used, it is replaced with a new roll film. (replaceable winding type).

In the case of such a winding and replaceable type, it is possible to make the fixing film thinner regardless of its durability, and the power consumption can be reduced.For example, using an inexpensive base material such as PET (polyester) film as the fixing film For example, a thin wall of about 12.5 uLm or less, which has been subjected to heat-resistant treatment, can be used.

Alternatively, as mentioned above, toner offset to the fixing film surface does not substantially occur, so if the thermal deformation and deterioration caused by use of the fixing film are small, the used sheet wound up on the winding shaft side can be By controlling the rewinding to the delivery shaft side in a timely manner,
Alternatively, the winding shaft side and the sending shaft side may be reversed and exchanged to be used multiple times (repeated rewinding type).

In the rewinding and repeated use type, the fixing film is a 25 gm thick polyimide resin film as a base material with excellent heat resistance and mechanical strength, and a release layer made of a fluororesin or the like with high mold release properties is provided on the surface. It is preferable to automatically control the pressure release mechanism to maintain the contact pressure between the heating body and the pressure roller in a released state when the rewinding and reverse running is zero.

In both cases of the rewinding type and the rewinding and repeating type, when a jam occurs, the above-mentioned problem can be eliminated by providing means for preventing the fixing film from moving as in the present invention.

When using multiple times, such as a rewinding type or an endless belt type, a felt pad is provided for cleaning the film surface, and the pad is impregnated with a small amount of algae type agent, such as silicone oil, and the pad is brought into contact with the film surface. If the fixing film is treated with insulating 2 or V resin, the static air that disturbs the toner image may be removed. Since this is likely to occur on the film, it is a good idea to use a grounded static eliminator brush to eliminate the static electricity, or charge the film within a range that does not disturb the toner image by applying 1<Iasumi pressure to the brush without grounding it. Furthermore, it is possible to add conductive powder fibers, such as carbon black, to the fluororesin to prevent the above-mentioned image holes caused by static electricity.Also, it is possible to remove static electricity from the pressure roller and make it conductive. This can also be done by similar means.

Further, an antistatic agent or the like may be applied or added.

Regardless of whether the fixing film is an endless belt type, a rewinding type, or a rewinding/repeating type, the fixing film can be easily replaced by having a cartridge structure that can be attached to and removed from a predetermined part of the front device 20. be able to.

(6) The configuration of the heating element 21 and the control of energization to the heating element 28 are not limited to those in the embodiment. The heating element 21 may be of a heat roller type, or the heating element may be a thick film resistor or PTC characteristic. A ceramic chip array or the like may be used, and the energization control may be a normal energization rather than a pulsed one.

The apparatus of the above embodiments is a transfer type electrophotographic copying apparatus,
The image forming process/means is electrofax paper/
An image is formed using heat-fusible toner on a recording material using a direct method in which a toner image is directly formed and carried on electrostatic recording paper, a magnetic recording image forming method, or other appropriate image forming process means, and then heated. The present invention can be effectively applied to various image forming apparatuses such as fixing type copying machines, laser beam printers, facsimile machines, microfilm league printers, display devices, and recording machines.

(Effects of the Invention) As described above, the present invention makes it possible to reduce the heat immersion of the heating body, which is the heating means, without causing fixation failure or offset in a toner image heat fixing type image forming apparatus. As a result, an image forming apparatus with low standby time, low power consumption, and low internal temperature rise can be realized. Furthermore, the thin fixing film can be used repeatedly over a long period of time without any problem of wrinkles.

Since a means is provided to prevent the fixing film from moving when a sheet (recording material) jam occurs, the user can prevent the jam from being caught between the heating body and the pressure member together with the fixing film when a sheet jam occurs. When removing the sheet, even if the jammed sheet is forcibly pulled out without releasing the mutual pressure between the heating element and the pressure member, the fixing film will not move and may cause wrinkles or curls in the fixing film. removed.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the configuration of the device of one embodiment, Fig. 2 is an enlarged view of the fixing device portion, Fig. 3 is a sectional view of the rotational load mechanism portion for the roller, and Fig. 4 is the main part of the device of the second embodiment. A partial diagram of
FIG. 5 is a sectional view of the rotational load mechanism and the fixing film movement prevention mechanism. 20 is the overall code of the fixing film, 40 is the fixing film,
21 is a heating element, 22 is a pressure roller, 44 is a pressure lever,
46 is a push button for releasing pressure, 60 is a fixing film movement prevention mechanism, and FBIPH2 is a paper feed and paper ejection detection sensor. Figure 5 Kaya Figure 4 Patent Applicant: Canon Co., Ltd.

Claims (1)

[Claims] (1) An image forming means that forms an unfixed toner image corresponding to target image information by carrying toner made of heat-meltable resin or the like on the surface of a recording material, a fixing film, and a driving drive for the fixing film. means, a heating body disposed on one side of the fixing film, and a heating body disposed on the other side of the recording material, the unfixed toner image bearing side of the recording material being connected to the heating body through the fixing film; The fixing film is provided with a pressure member that brings the surfaces of the image into close contact with each other, and is driven to run in the same direction at the same speed as the conveyance speed of the recording material carrying the unfixed toner image conveyed from the image forming means side, and the pressurizing film. a toner image heat fixing unit that introduces the recording material between the recording member and the recording member and heats and fixes the unfixed toner image on the surface of the recording material; and a jam unit that detects the occurrence of a jam in the recording material conveyed through the recording material conveyance path of the apparatus. Even if a tensile external force is applied to the detecting means and the fixing film that has come to a traveling stop state due to an emergency stop of the device operation based on a jam detection signal of the jam detecting means, the tensile external force is not applied. An image forming apparatus comprising: means for resisting movement of the fixing film.