JPH07248695A - Fixing device - Google Patents

Abstract

PURPOSE:To rectify a dented deformation generated on the nip part of a pressuring roller during pre-rotation so as to solve the problem of the fixing failure of an image by conducting electricity to a heating body during the pre-rotation of the pressuring roller immediately after main power is given to a device main body. CONSTITUTION:After main power is given to the device main body, the pre- rotations of a fixing film 7 and a pressuring roller 10 are started following the pre-rotation of a main motor. After the completion of one round after a specified period since rotation start was confirmed on a rotary sensor part, electricity supply is started to a heating body 1. Further, electricity supply to the heating body 1 is stopped simultaneously when the main motor is stopped. In this case, temperature adjusting temperature control when electricity is conducted to the heating body 1 is performed in three stages by means of the detected temperature of the fixing film 7 detected by a temperature inspection element 5 immediately after main power is given. Thus, by conducting electricity immediately after the main power is inputted, the pressuring roller 10 can be heated and heat sufficient for rectifying a dented and deformed part can be given.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material carrying a visible image (hereinafter referred to as a toner image) to be heat-fixed adhered to a heating body through a film so that the heating body passes through the film. The present invention relates to a film heating type fixing device that applies heat energy to a recording material to heat and fix a toner image.

This apparatus is used in an image forming apparatus such as a copying machine, a laser beam printer, a facsimile, a micro film reader printer, an image display device and a recording paper.
A recording material (electrofax sheet, electrostatic recording sheet, transfer material sheet) as an image carrier is formed by using a toner made of a heat-meltable resin by an appropriate image forming process means such as electrophotography, electrostatic recording and magnetic recording. , Printing paper, etc.)
It can be utilized as an image fixing device that heats and fixes an unfixed toner image corresponding to the target image information formed on the surface of the recording medium by the direct method or the indirect method as a permanently fixed image on the surface of the recording material carrying the image.

[0003]

2. Description of the Related Art Conventionally, as a heating type fixing device, an unfixed toner image is formed by 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 fixing device of a heat roller fixing system that heats the recording material while nipping and transporting the recording material is often used.

However, the fixing device of the heat roller fixing system firstly needs a time until the temperature rises to a predetermined temperature (time for prohibiting the image forming operation), that is, a so-called wait time, and secondly, the heat capacity. Therefore, a relatively large electric power is required. Thirdly, the rotating roller has a high roller temperature, so a heat-resistant special bearing is required. Fourthly, the roller is directly in contact with the hand, Fifthly, there are drawbacks such as danger and need of a protective member, and fifthly, the recording material is wound around due to the roller fixing temperature and the curvature to cause a jam.

Therefore, as a fixing device of the heating system which does not have the above-mentioned drawbacks, recently, a fixing device of the film heating system as described above has attracted attention, and research and development for its practical use have been advanced.

The system, apparatus, etc. disclosed in, for example, Japanese Patent Laid-Open No. 63-313182 according to the applicant's earlier proposal belong to this, and include a thin heat-resistant film (sheet), a moving driving means for the film, and A heating body fixedly supported on one side of the film and a recording body to be fixed on the other side of the heating body through the film so as to be fixed to the heating body. The film has a pressure member for closely contacting the developed image bearing surface of the material, and the film is in the same direction as the recording material to be image-fixed conveyed and introduced between the film and the pressure member at least when image fixing is performed. The developed image carrying surface of the recording material is heated through the film by traveling at a speed and passing through a fixing nip portion formed by pressure contact between a heating body and a pressing member with the traveling moving film interposed therebetween. Image by heating with body (undecided The heating means and device are based on applying thermal energy to the toner image) to soften and melt it, and then separating the film and the recording material, or separating the film and the recording material after the toner has cooled and solidified. .

As the heating element, a horizontally elongated heat-insulating, insulating, low-heat-capacity heater substrate having a widthwise direction of the film is formed in a linear or strip shape along the length of the film contact surface side. A heating element having a low-heat-capacity energizing heating resistor (heating element) is used, and the heating element generates heat when electric power is supplied between both ends of the heating element. The temperature of the entire body rapidly rises, and the heat of the heating body is applied to the recording material via the film.

The temperature control of the heating element is carried out by a temperature sensor provided on the heating element, a microcomputer of the image forming apparatus main body and a heating element driving (energizing heat generation) circuit, and the temperature is controlled to a predetermined fixable temperature. It Although the heating element is at a high temperature, the film is moved and driven on the heating element at a predetermined temperature at least when the heating element generates heat, so local thermal deformation of the film does not occur and stable image fixing is performed. Is executed.

Such a film heating type fixing device has characteristics such as a short wait time and is a fixing device that meets the needs of the times.

[0010]

However, in the above-mentioned conventional example, the nip portion of the pressure roller may be dented and deformed during standing for a long time. Due to this dent deformation, the pressure roller cycle is changed. There has been a problem that defective fixing of an image occurs.

[0011]

In order to solve the above problems, the present invention is directed to a movable film, a heating body which is in contact with the film and generates heat when energized, and the heating body is pressed through the film. A fixing device which has a pressure roller, and which fixes and conveys a recording material carrying an unfixed image in a nip formed by the film and the pressure roller, immediately after turning on the main power of the apparatus main body. The heating element is energized during the pre-rotation of the pressure roller.

[0012]

【Example】

Embodiment 1 (1) Image Device Example FIG. 3 shows a schematic configuration of an example of an image forming device using a fixing device 60 described later according to the present invention.

The image forming apparatus of this embodiment is a fixed original-moving optical system type, a rotary drum type, or a transfer type electrophotographic copying apparatus.

When the original 19 is placed on the fixed original glass 20 and the required copying conditions are set and the copy start key is pressed, the photosensitive drum 39 is rotated at a predetermined peripheral speed in the clockwise direction indicated by the arrow. It is driven to rotate.

Further, the light source 21 (22 is a reflection shade) and the first mirror 23 move forward along the lower surface of the document table glass 20 from the home position on the left side of the glass to the right side of the glass at a predetermined speed V, and the second mirror. By moving the third mirrors 24 and 25 forward in the same direction at a speed of V / 2, the downward image surface of the document 19 placed on the document glass 20 is illuminated and scanned from the left side to the right side, and the illumination scanning is performed. The light reflected from the document surface is formed by the imaging lens 2
9. Imaging exposure (slit exposure) is performed on the surface of the rotating photosensitive drum 39 via the fixed fourth to sixth mirrors 26, 27, and 28.

Prior to this exposure, the surface of the rotary photosensitive drum 39 is uniformly charged to a predetermined positive or negative potential by the primary charger 30, and the above-mentioned exposure is performed on this charged surface. Then, an electrostatic latent image having a pattern corresponding to the original image is sequentially formed on the surface of the drum 39. The electrostatic latent image formed on the surface of the photosensitive drum 39 is transferred to the developing roller 32 of the developing device 31.
To be visualized as a toner image.

On the other hand, a transfer material sheet P as a recording material is fed by a paper feeding means (not shown) and is introduced into a transfer portion between the drum 39 and the transfer charger 34 at a predetermined timing through a guide 33. Drum 3 by receiving a transfer corona
The toner visible image on the surface of the drum 39 in contact with the sheet 9 is sequentially transferred to the surface of the sheet P.

The sheet P that has passed through the image transfer portion is sequentially separated from the surface of the drum 39 by separating means (not shown) (for example, a separating belt disposed at the end of the drum), and is discharged by the discharging needle 35 to remove the charges on the back surface. The sheet is introduced into the fixing device 60 by the conveying section 38 and the guide 18, undergoes toner image fixing as will be described later, and is discharged outside the apparatus as an image formed product.

The surface of the drum 39 after the transfer is the cleaning device 3
A cleaning blade 37 of No. 6 removes stains such as residual toner to form a clean surface, and is repeatedly used for image formation.

When the moving optical members 21 to 25 that have moved in the forward direction reach a predetermined forward movement end point, they are returned to the initial home position and return to the initial home position, and wait until the start of the next copy cycle (back of the optical system). Process).

(2) Example of Fixing Device a) Device Configuration FIG. 1 is a side view of an example of the fixing device 60 according to the present invention, and FIG.
[Fig. 3] is a model diagram of a layer structure of a fixing film.

Reference numeral 7 denotes an endless belt-shaped fixing film, which has a left driving roller 8 and a right driven roller 9, and a low heating capacity linear heating element 1 as a heating element arranged below the rollers 8 and 9. The three members 8, 9 and 1 are suspended and stretched.

The driven roller 9 also serves as a tension roller for the endless belt-shaped fixing film 7, and the fixing film 7 is rotated at a predetermined peripheral speed in the clockwise direction as the driving roller 8 is rotated in the clockwise direction, that is, the image forming portion. The unfixed toner image Ta conveyed from the side is rotationally driven at the same peripheral speed as the conveying speed of the recording material P carrying the upper surface without wrinkles, meandering, or speed delay.

Reference numeral 10 denotes a pressure roller having a rubber elastic layer 12 having a good releasability such as silicon rubber as a pressure member. The pressure roller 10 has the lower film portion of the endless belt-shaped fixing film 7 sandwiched therebetween. The lower surface of the heating element 1 is pressed against the lower surface of the recording material P by a biasing means (not shown) with a contact pressure of, for example, 4 to 7 kg, and is rotated counterclockwise in the forward direction of the conveyance direction of the recording material P. Rotate around 11.

The heating element 1 is a linear heating element with a low heat capacity having a longitudinal direction in a direction intersecting the plane movement direction of the film 7 (width direction of the film), and includes a heater substrate 3, an energization heating resistor (heating element) 4, It is composed of a temperature measuring element 5 and the like, and is fixedly supported by being attached and held to the heater support 2.

The heater support 2 fixes the heating body 1 to the fixing device 60.
And those having heat insulating properties, high heat resistance, and rigidity for thermally supporting the image forming apparatus, such as PPS (polyphenylene sulfide), PAI (polyamide imide), and PI.
(Polyimide), PEEK (polyether ether ketone), high heat resistant resin such as liquid crystal polymer, or a composite material of these resins and ceramics, metal, glass or the like.

The heater substrate 3 is a member having heat resistance, insulation properties, and low heat capacity. As an example, the heater substrate 3 has a thickness of 1.0 mm and a width of 16 m.
It is an alumina substrate having a length of m and a length of 340 mm.

The heating element 4 is formed along the length of the substrate 3 on the lower surface (on the side facing the film 7) substantially in the center, for example, Ag / P.
An electric resistance material such as d (silver-palladium) or Ta ₂ N is applied by screen printing or the like to a thickness of about 10 μm and a width of 1 to 3 mm, and a heat-resistant glass 6 as a surface protection layer is further applied on the surface of the protective layer 6 to about 1
It is coated with 0 μm.

As an example, the temperature measuring element 5 has a low heat capacity such as a Pt film coated on the upper surface of the substrate 3 (the surface opposite to the surface on which the heating element 4 is provided) substantially centrally by screen printing or the like. This is a resistance temperature detector. As the temperature detecting element, a thermistor having a low heat capacity may be arranged in contact with the substrate 3.

In the case of the heating element 1 of the present example, the heating element 4 having a linear or strip shape is energized from both ends in the longitudinal direction, and the heating element 4 is caused to generate heat over substantially the entire length. Energization is A
It is C100V, and the energization power is controlled by controlling the energizing phase angle by an energization control circuit (not shown) including a triac according to the temperature detected by the temperature detecting element 5.

The fixing film 7 has heat resistance, releasability, durability, etc., and generally has a layer pressure of 100 μm or less, preferably 40.
A single-layer or composite-layer film having a thickness of μm or less can be used.

FIG. 2 is a schematic diagram of the layer constitution of an example of the composite layer film, and this example is a two-layer constitution film. 7b is a heat-resistant layer as a base layer of the fixing film,
Reference numeral a is a release layer laminated on the outer surface (surface facing the toner image) of the heat resistant layer 7b.

The heat-resistant layer 7b is made of, for example, polyimide, polyetheretherketone (PEEK), polyethersulfone (PES), polyetherimide (PEI), polyparabanic acid (PPA) or other high heat resistant resin film, or N.
Materials having excellent strength and heat resistance such as metals such as i, SUS, and Al can be used.

The release layer 7a is made of, for example, a fluororesin such as PTFE (polytetrafluoroethylene), PFA or FEP,
Silicone resin or the like is preferable (PTFE in this example). The resistance value of the surface of the fixing film 7 can be lowered by mixing a conductive material such as carbon black, graphite, or conductive whiskers into the release layer 7a. Accordingly, the toner contact surface of the fixing film 7 can be prevented from being charged.

The lamination property of the release layer 7a with respect to the heat-resistant layer 7b is determined by adhesive lamination of the release layer film, electrostatic coating (coating) of the release layer material, lamination by film forming technology such as vapor deposition, CVD, heat-resistant layer material. It can be performed by forming a two-layer film by co-extrusion.

B) Fixing Execution Operation The image forming apparatus (FIG. 3) of the above-described example performs an image forming operation in response to the image forming start signal, and the recording material sheet carrying the unfixed toner image Ta conveyed to the fixing device 60 on its upper surface. P is guided by the guide 18 and enters between the fixing film 7 and the pressure roller 10 at the pressure contact portion (fixing nip portion) between the heating body 1 and the pressure roller 10, and the unfixed toner image surface becomes a sheet. The heating body 1 and the pressure roller are in close contact with the lower surface of the fixing film 7 which is rotated in the same direction and in the same direction as the conveying speed of P without overlapping with the fixing film 7 without causing surface deviation, wrinkling, or twisting. It passes through the mutual pressure contact portion with 10 while receiving a clamping pressure.

Since the heating element 1 is electrically heated by the image formation start signal at a predetermined timing, the toner image Ta
Is softened by being heated at the press contact portion and becomes a fusion image Tb.

In the fixing film 7, the edge portion S (having a radius of curvature of about 2 mm) of the heater support 2 having a large curvature is
The traveling direction turns at a steep angle (the bending angle θ is about 45 degrees). Therefore, the sheet P conveyed while passing through the pressure contact portion in a state of overlapping with the fixing film 7 is curvature-separated from the fixing film 7 at the edge portion S, and is discharged to the discharge tray. By the time the sheet is discharged, the toner is sufficiently cooled and solidified and is in a state of being completely fixed on the sheet P (toner image Tc).

In the present example, the heat capacity of the heating element 4 and the substrate 3 of the heating element 1 is small, and these are the support 2
Since the surface temperature of the heating element 1 at the pressure contact portion is adiabatically supported by
Since the temperature is raised to a temperature sufficiently high relative to (fixable temperature for fixing to), there is no need to preheat the heating element 1 (so-called standby temperature adjustment), and energy saving can be realized.
Moreover, the temperature rise inside the machine can be prevented.

C) Heater control immediately after turning on the main power source After the main power source of the apparatus main body is turned on, the fixing film 7 and the pressure roller 10 also start to rotate forward as the main motor (not shown) rotates forward. In the system of this embodiment, it takes 1.5 seconds for the fixing film 7 to rotate once.

In the rotation sensor portion (not shown), after confirming that one revolution is made 1.5 seconds after the start of rotation, energization of the heating element 1 is started. The energization time to the heating element 1 is 5 seconds. This is for synchronizing with the pre-rotation time, and the power supply to the heating element 1 is stopped at the same time when the main motor is stopped. That is, the pre-rotation time is 6.5 seconds.

The temperature control temperature at the time of energizing the heating element 1 is controlled as follows. Temperature measuring element 5 immediately after the main power is turned on
The temperature control temperature is controlled in three stages according to the detected temperature of the fixing film 7 detected by Immediately after turning on the main power, the detected temperature is 11
When the temperature is 0 ° C. or lower, the controlled temperature is 225 ° C. Similarly, when the detected temperature is 110 ° C. to 140 ° C. or less, the temperature control temperature is set to 200 degrees, and when the detection temperature is higher than 140 degrees C, the temperature control temperature is set to 180 degrees and control is performed.

By energizing for 5 seconds immediately after turning on the main power,
The pressure roller 10 can also be heated, and a sufficient amount of heat to restore the dented and deformed portion can be given. The temperature control temperature is divided into three stages. It is assumed that the temperature of the pressure roller 10 is high when the detection temperature of the temperature detection element 5 immediately after the main power is turned on is high, and the dent deformation amount is small. Because there is no need to raise it.

FIG. 4 shows a timing chart of the pre-rotation after the main power source of the main body is turned on and the energization of the heating element.

As described above, in this embodiment, since heat is applied to the pressure roller during the pre-rotation, it is possible to correct the dent of the pressure roller and prevent fixing failure.

Example 2 The system is the same as that of Example 1 except for the heater control immediately after turning on the main power source.

Immediately after the main power is turned on, a heater control is provided in the image forming apparatus. The timer counts the time from the end of copying. This timer shall operate even after the main power is turned off.

Next, when the main power is turned on, the value of the counter is first read. Thereby, the time after the pressure roller 10 has stopped can be known. The dent deformation amount in the nip portion of the pressure roller 10 is closely related to the stop time of the pressure roller 10, and the dent deformation amount can be estimated from the stop time. That is, by knowing the stop time of the pressure roller 10, it is possible to determine the energization time to the heating element 1 required to recover the dent deformation.

The actual energizing time is controlled as follows.

When the final copy is completed within 0 to 1 hour, the heater 1 is not energized because it has not been dented and deformed. If it is more than one hour and less than 24 hours after the end of the final copy, the heating element 1 is energized for 5 seconds during the pre-rotation. When it exceeds 24 hours after the end of the final copy, the heating element 1 is energized for 10 seconds during the pre-rotation.

The control of the controlled temperature is the same as in the first embodiment.

FIG. 5 is a graph showing the relationship between the elapsed time after the end of the final copy and the energization time to the heating element.

As described above, according to this embodiment, it is possible to more accurately correct the deformation of the pressure roller without waste and prevent the fixing failure.

[0054]

As described above, according to the present invention, it is possible to recover the dent deformation generated at the nip portion of the pressure roller during the pre-rotation. Therefore, it is possible to solve the image fixing defect that occurs due to the dent deformation and that occurs in the pressure roller cycle.

Further, by controlling the energization amount to the heating body according to the dent deformation amount of the pressure roller, the required energization amount can be minimized.

Further, by energizing the heating element at the time of pre-rotation, there is also an effect of warming the inside of the apparatus at the time of start-up, and the temperature rise at the time of copying becomes faster correspondingly, and the effect of improving the fixing property is also obtained.

[Brief description of drawings]

FIG. 1 is a side view of a fixing device according to a first exemplary embodiment and a second exemplary embodiment.

FIG. 2 is a model diagram of a layer configuration example of a fixing film in Examples 1 and 2.

FIG. 3 is a schematic diagram of an example of an image forming apparatus according to the first and second embodiments.

FIG. 4 is a timing chart of pre-rotation after turning on the main power source of the main body and energization of the heating element in the first embodiment.

FIG. 5 is a graph showing the relationship between the elapsed time after the end of the final copy and the energization time to the heating body in Example 2.

[Explanation of symbols]

 1 Heater 3 Heater Substrate 4 Heater 5 Temperature Measuring Element 7 Fixing Film 10 Pressure Roller

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hisaaki Senba 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (3)

[Claims] 1. A movable film, a heating body that is in contact with the film and generates heat when energized, and a pressure roller that presses the heating body through the film. In a fixing device that performs fixing by nipping and conveying a recording material carrying an unfixed image in the formed nip, energize the heating element during the pre-rotation of the pressure roller immediately after turning on the main power of the apparatus main body. Fixing device characterized by. 2. The fixing device according to claim 1, wherein the heating body is energized during the pre-rotation after the film is moved. 3. A measuring means for counting the time from the end of the fixing operation to the next turning on of the main power source, and the output from this measuring means controls the energization time to the heating body during the previous rotation. The fixing device according to claim 1 or 2, characterized in that: