JP2000315027A - Heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate, without an increase in the size of a device main body, trouble due to a change in a speed at which a material to be heated is sandwiched and carried, by providing a speed control means whereby the driving speed of a device used for a material to be heated next is determined by use of the speed of a film when a material to be heated is passed through a pressure contact nip. SOLUTION: On the external face of a fixing film 12, a light reflecting material as a marking part is provided. A reflection type sensor 21 detects reflected light from the reflecting material each time the light reflecting material is passed, and transmits the signal to a CPU 100. In the case the rotating speed of a fixing film 12 calculated from input information from the reflection type sensor 21 is higher than a specific speed, the CPU 100 exerts control so as to drop the speed of a fixing-device drive motor M2 by a motor driver 101. In the case the rotating speed of the fixing film 12 calculated from the input information from the reflection type sensor 21 is lower than the specific speed, it exerts control so as to drop the speed of the fixing-device drive motor M2 by the motor driver 101.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heating device and an image forming apparatus.

More specifically, it has a heating element, a film, and a pressure member which is pressed against the heating element with the film interposed therebetween and is driven and rotated, and is formed by the heating element and the pressure member with the film interposed therebetween. A heating device of a film heating type, in which the heating material transferred from the upstream processing unit is introduced into the press-contact nip portion and nipped and conveyed, thereby applying heat of the heating body to the heating material through the film. And an image forming apparatus including the heating device.

[0003]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, an LBP, a facsimile, a microfilm reader printer, an image display (display) device, and a recorder, an appropriate method such as electrophotography, electrostatic recording, and magnetic recording is used. Indirect (transfer) method to the surface of a recording material (transfer material sheet, electrofax sheet, electrostatic recording sheet, printing paper, etc.) using a developer (toner) made of heat-meltable resin etc. by the image forming process means Alternatively, a heating device (image heating device, image heating / fixing device) that heats and fixes an unfixed toner image corresponding to target image information formed and supported by a direct method as a permanently fixed image on the surface of the recording material is used. Heated by a heating roller as a heating body maintained at a temperature of, and a pressing roller as a pressing member having an elastic layer and pressed against the heating roller. Heat roller method is widely used for heating process while nipping and conveying the recording material as.

[0004] In addition, a flash heating method,
Various systems and configurations such as an oven heating system and a hot plate heating system are known and are in practical use.

[0005] In recent years, instead of such a method, a fixedly supported heating element, a heat-resistant film (fixing film) conveyed while being pressed against the heating element, and a heating target through the film. An unfixed image formed and carried on the surface of the recording material by applying heat of the heating body to the recording material via a film, which has a pressure member for bringing the recording material as a material into close contact with the heating body. A heating device (film heating system) having a system and a structure for heating and fixing the recording material surface has been devised.

[0006] Not only as a fixing device, but also as a means for heating a recording material carrying an image to improve the surface properties (such as gloss), assuming an assembling process, and as a means for heating a material to be heated. Can be widely used.

[0007] Such a film heating type heating apparatus can use a heating element having a low heat capacity or a thin film having a rapid temperature rise, so that it is possible to save power and shorten the wait time (quick start property). This has the advantage that the temperature inside the apparatus such as an image forming apparatus can be reduced, and is effective.

[0008]

As in the case of a heating device of a heat roller type or a film heating type, a material to be heated is introduced into a pressure nip portion between a heating body and a pressing member, and the material is heated by the two members. 2. Description of the Related Art In an apparatus that heats a material to be heated by being nipped and conveyed, the speed of nipping and conveying the material to be heated by the apparatus fluctuates depending on the temperature state of constituent members. For example, a heating device of a film heating system, which drives and rotates a pressing member (hereinafter, referred to as a pressing roller) that presses the heating body through the film, thereby sliding the film to the heating body. In a pressure-member-driven device that sandwiches and transports a film or a film and a material to be heated, together with a pressure nip between a heating element and a pressure roller, the temperature of the pressure roller increases with the operation of the device. Thus, the outer diameter of the pressure roller increases due to the thermal expansion of the rubber portion.

Since the pressure roller is normally driven to rotate at a constant rotational speed, when the pressure roller is at a high temperature, the thermal expansion is greater than at a low temperature, the rotational peripheral speed is increased, and the material to be heated is nipped and conveyed. Speed will be faster.

[0010] That is, there is a difference in the speed of holding and conveying the material to be heated by the heating device depending on the temperature state of the pressure roller.

For this reason, for example, when this heating device is used in an image forming apparatus as an image heating and fixing device, conveyance of a recording material in an image forming unit, for example, an image transfer unit, which is a processing unit upstream of the heating device. Since the recording material is maintained at a predetermined constant, when the recording material reaches the recording material press-contact nip portion (fixing portion) of the heating device from the image transfer portion and enters the nipping and conveying state, when the pressure roller is in a high temperature state, A state in which the recording material nipping conveyance speed in the fixing unit of the heating device is higher than the recording material conveyance speed in the image transfer unit occurs, and the heating device pulls the recording material. Causes image blurring.

In consideration of the recording material pulling phenomenon, if the recording material nipping and conveying speed by the heating device is set to be lower than the recording material conveying speed in the image transfer section from the beginning,
When the temperature of the pressure roller is still low, an unnecessary loop (slack) is formed on the recording material in the recording material transporting section between the image transfer section and the fixing section of the heating device, and the image transfer section performs an image transfer. The direction of separation of the recording material from the image carrier and the angle of incidence of the recording material on the fixing unit of the heating device become unstable. An offset or the like occurs in a fixing unit of the apparatus. Further, when the recording material used for passing the paper is thick, image blur occurs in the image transfer unit due to the stiffness of the recording material.

In order to eliminate the adverse effects caused by the pulling phenomenon of the recording material and the unnecessary loop formation phenomenon due to the fluctuation of the recording material nipping and conveying speed of the heating device, an image transfer unit and a fixing unit of the heating device are required. In this case, it is necessary to increase the distance of the recording material transporting section between them, thereby reducing the time during which the recording material is simultaneously present in the image transfer section and the fixing section of the heating device.

However, in the case of an image forming apparatus such as an A3 machine that uses a long recording material and passes a recording material, the recording material conveyance distance between the image transfer unit and the fixing unit becomes too long, and the image forming apparatus body becomes In fact, it was quite large.

Japanese Patent Application Laid-Open No. Hei 7-261584 proposes a method of detecting the amount of loops of a recording material or detecting the transport speed of the recording material and changing the driving speed of a pressure roller. Have been. However, in these methods, control cannot be performed until the first recording material reaches the heating device (fixing device), and when the recording material is transported at a high speed, the control may not be performed in time.

A method has also been proposed in which the temperature of the pressure roller is measured, and the amount of expansion is predicted to change the drive speed. However, more accurate control cannot be performed due to a large error.

In Japanese Patent Application Laid-Open No. Hei 8-190298, a plurality of reflectors are provided on a film, and the peripheral speed of the film is detected by reading the ON / OFF cycle of the reflection type sensor. A method has been proposed in which the driving speed of the pressure roller is sequentially changed so that
However, in this method, a plurality of reflectors must be provided on the film, which increases the cost. In addition, it is difficult to perform processing with high precision because the intervals between the reflectors must be equalized. In addition, since these signals must be sequentially processed at a high speed, a more expensive CPU is required.

Accordingly, the present invention reduces the above-mentioned adverse effects caused by fluctuations in the material-to-be-heated sandwiching / conveying speed of this type of heating device by increasing the distance of the material-to-be-heated conveyed to the processing section upstream of the heating device. It is an object of the present invention to eliminate the problem without increasing the size of the apparatus main body.

[0019]

According to the present invention, there is provided a heating apparatus and an image forming apparatus having the following constitutions.

(1) A heating member, a film, and a pressing member which is pressed against the heating member with the film interposed therebetween and is driven to rotate, and is formed by the heating member and the pressing member with the film interposed therebetween. In the heating device that applies the heat of the heating body to the material to be heated through the film by introducing and heating the material to be heated conveyed from the processing section on the upstream side to the nip portion, the film is provided with the film. A marking unit, a detecting unit for detecting the marking unit, a film speed detecting unit for calculating a rotation speed of the film from a marking unit detection time interval of the detecting unit, a unit for varying a driving speed of the apparatus, A heating device comprising: speed control means for determining a driving speed of a device for a next material to be heated by using a speed of a film when the heating material passes through a pressure nip portion.

(2) In the heating device according to (1), the marking portion provided on the film is obtained by mixing a high-reflectivity powder with an adhesive at a predetermined ratio, partially applying the powder to the film surface, and drying. A heating device characterized in that it is made to be heated.

(3) The heating device according to (2), wherein the high reflectance powder is titanium dioxide powder or calcium-based artificial pearl powder.

(4) In the heating device according to the above (1), the marking portion provided on the film is formed by applying an adhesive partially to the surface of the film and forming a high reflectivity made of glass or the like on the adhesive layer. A heating device characterized by forming a reflective layer in which beads are arranged and drying the layer.

(5) In the heating device according to the above (1), the marking portion provided on the film is obtained by partially applying an adhesive to the film surface and forming a high reflectance such as a metal film on the adhesive layer. A heating device characterized in that a reflection layer of the film is formed and dried.

(6) The heating device according to (1), wherein the marking portion provided on the film is different from the surface of the surrounding film in surface resistance, dielectric constant, or magnetism. .

(7) In the heating device according to the above (1), the marking portion provided on the film is provided with a hole in the surface of the film, and the marking member is passed through the hole to bond or fuse between the marking members. A heating device, characterized in that the heating device is supported by a heating device.

(8) In the heating device according to the above (1), the marking portion provided on the film is made of a material having different surface reflectance, surface resistance, dielectric constant, or magnetism on the surface of the surrounding film. A heating device characterized by being formed by coating, vapor deposition or welding.

(9) The heating device according to any one of (1) to (6), wherein the marking portion provided on the film has a top coat layer having a high transmittance as an uppermost layer. apparatus.

(10) In the heating device according to any one of the above (1) to (9), the detecting means for detecting the marking portion is an optical reflected light detecting means, a contact resistance detecting means, or a dielectric constant. A heating device, which is a detection unit or a magnetic detection unit.

(11) A fixedly supported heating element, a film, and a pressing member which is pressed against the heating element with the film interposed therebetween and is driven and rotated, and the heating element and the pressing member sandwich the film. The film to be heated conveyed from the upstream processing section is introduced between the film in the press-contact nip portion and the pressing member to be formed, and the film is slid and moved to the heating body by the driving rotation of the pressing member. In the heating device that applies the heat of the heating body to the material to be heated through the film by nipping and pressing the press-contact nip portion together with the material to be heated, the film is formed of an insulator, and a coating portion is provided on the outer periphery thereof. The coating member is configured to have a lower surface resistance value or reflectivity than the surrounding film, and a part of the outer peripheral surface of the film has a marking portion that is not coated, and detects the marking portion. Has knowledge means calculates the rotation speed of the film from the marking unit detection time interval of the same detection means,
A heating device characterized in that the driving speed of the pressing member is variable and the rotation speed of the film can be controlled within a predetermined range.

(12) A fixedly supported heating element, a film, and a pressing member which is pressed against the heating element with the film interposed therebetween and is driven and rotated, and the heating element and the pressing member sandwich the film. The film to be heated conveyed from the upstream processing section is introduced between the film in the press-contact nip portion and the pressing member to be formed, and the film is slid and moved to the heating body by the driving rotation of the pressing member. In the heating device that applies heat of the heating body to the material to be heated through the film by pinching and conveying the press-contact nip portion together with the material to be heated, the marking part and the marking part are detected on the surface of the film. Film speed detecting means for calculating the rotational speed of the film from the marking section detection time interval of the detecting means, and means for varying the driving speed of the apparatus, and Is pressed Using the speed of the film as it passes through the gap, the speed control means for determining the driving speed of the device for the next material to be heated. A heating device characterized in that a reflection member is provided on a surface.

(13) In the heating device according to any one of the above (1) to (12), one round of the film immediately before the arrival of the material to be heated is determined by the material detection means upstream of the press nip. A heating device that determines the driving speed of the device by determining the speed based on the time.

(14) The heating device according to any one of (1) to (13), wherein the film is an endless film.

(15) The heating device according to any one of (1) to (14), wherein the material to be heated is a recording material carrying an image to be heated.

(16) The heating apparatus according to any one of the above (1) to (15), wherein the upstream processing section is an image transfer section for a recording material.

(17) In an image forming apparatus having an image forming section for a recording material and an image fixing means for heating and fixing an unfixed image on the recording material conveyed from the image forming section, the above image fixing means Is the heating device according to any one of (1) to (16).

(18) The image forming apparatus according to (17), wherein the image forming section for the recording material is an image transfer section from the image carrier to the recording material.

<Operation> The heating device of the pressure member driving system / film heating system has a means for detecting the speed of the film and a means for varying the driving speed of the device. By using the speed of the film when passing through the film to determine the driving speed of the device for the next heated material, the adverse effect due to the fluctuation of the heated material sandwiching and conveying speed is reduced by the processing on the upstream side of the heating device. The problem can be solved without increasing the transport distance of the material to be heated with respect to the unit, and thus without increasing the size of the apparatus main body.

Further, in an image forming apparatus provided with the heating device as an image heating and fixing device, it is possible to prevent the image from being disturbed due to a change in the recording material transport speed due to the thermal expansion of the pressing member.

When controlling the drive speed of the pressing member by detecting the speed of the film and thereby predicting the transport speed of the material to be heated, the control is performed by detecting the time of one rotation of the film, thereby controlling the speed of the film. Since only one marking portion is required, it can be manufactured at low cost. In addition, since there is no need for accuracy between the marking portions, manufacture is easy. Also,
Since the signal only needs to be processed once for each material to be heated, an inexpensive CPU is sufficient.

Further, in the case of the first heated material, that is, the film speed is determined by multiplying the film speed when there is no heated material in the press-contact nip portion by the paper coefficient to determine the film speed. The film speed can be controlled before reaching the heating device, and the material to be heated can always be stably transported. In addition, it can respond to high speed.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) Example of Image Forming Apparatus FIG. 1 is a schematic configuration diagram of an image forming apparatus according to this embodiment. The image forming apparatus of the present embodiment is a laser copying machine using a transfer type electrophotographic process and having an image reading scanner unit.

The image forming apparatus main body A has an image reading scanner section B as image reading means for reading image information of a document at an upper portion, and an image forming section C as image forming means (image forming section) at a lower portion. , And a seat deck D is further assembled thereunder.

A) The image reading scanner unit B 202 is a platen glass fixed and arranged horizontally, and the image surface to be read, such as a book document such as a book, thick paper, or curled paper, or a sheet-shaped document, is placed on the lower side. The document is placed in accordance with a predetermined placement standard, and is set in a stationary state by pressing the back surface with the document pressing plate 203.

When the reading start key is pressed, the movable scanning unit including the scanning system light source 201 and the scanning system mirror 204 disposed on the lower side of the platen glass 202 moves from the home position indicated by the solid line on the left side of the platen glass to the platen glass. A predetermined forward drive is performed along the lower surface of the glass in the direction of arrow a, which is the right side.

Thus, the downward image surface of the original placed and set on the platen glass 202 is sequentially illuminated and scanned from the left side to the right side, and the original surface reflected light of the illumination scanning light is received through the lens 205. The light is incident on an element (photoelectric conversion element) 206, photoelectrically read, processed by an image processing unit, converted into an image information electric signal, and transmitted to the laser scanner 111 of the image forming unit C.

When the movable scanning unit moves to a predetermined forward end point, it is turned backward and returned to the initial home position.

B) The image forming section C 112 is a rotating drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) as an image carrier. The photoconductor drum 112 is driven to rotate clockwise at a predetermined peripheral speed (process speed). In the rotation process, the photoconductor drum 112 is subjected to a uniform charging process of a predetermined polarity and potential by a charger, and a laser is applied to the uniformly charged surface. By receiving laser beam scanning exposure corresponding to image information from the scanner 111 and the image writing optical system 113, an electrostatic latent image corresponding to the scanning exposure pattern is formed on the surface of the photosensitive drum 112.

The electrostatic latent image formed on the surface of the photosensitive drum 112 is developed as a toner image by the developing device 114, and the toner image is transferred to the photosensitive drum 112 and the transfer charging roller 1.
In the image transfer section, which is a contact nip portion with the sheet 15, a sheet (transfer sheet, sheet, paper) as a recording material fed from the sheet supply section to the image transfer section at a predetermined control timing. It is transcribed sequentially.

The sheet on which the toner image has been transferred through the image transfer unit is sequentially separated from the surface of the photosensitive drum 112, is conveyed to a fixing device 118 through a conveying unit 117, and is heated and pressed by the fixing device. Receive a fixing process of the unfixed toner image.

After the sheet is separated, the rotary photosensitive drum 112 is subjected to a process of removing residual adhered contaminants such as transfer residual toner by a cleaning device, and is subjected to a static elimination process by an eraser lamp or the like to be repeatedly subjected to image formation.

In the case of the single-sided print mode, the sheet that has passed through the fixing device 118 has a discharge tray (or sorter) 120 disposed outside the apparatus by a discharge roller 119.
Discharged and loaded.

In the case of the double-sided print mode, a sheet on which an image has been formed on the first surface discharged from the fixing device 118 is nipped by the discharge roller 119 and the rear end of the sheet passes the branch point 207. With discharge roller 11
9 is reversed, and once placed on the sheet double-sided tray 121, is conveyed by the conveying rollers 104 and 105,
After the sheet reaches the registration roller 106 and is re-fed to the image transfer unit at a predetermined control timing, an image is formed on the second surface of the inverted sheet in the same manner as described above. The sheet is discharged and stacked on the tray 120.

Here, the image forming apparatus main body A is provided with the image reading scanner section B by the laser scanner 111 as described above.
When the processing signal of the image processing section is input, the apparatus functions as a copier, and when the output signal of an external computer is input, the apparatus functions as a printer. Further, if a signal from another facsimile apparatus is received or a signal from the image processing unit of the image reading scanner unit B is transmitted to another facsimile apparatus, the apparatus functions as a facsimile apparatus.

C) Sheet Deck D A sheet cassette 1 is mounted below the image forming section C. The sheet cassette 1 is composed of a lower cassette 1a and an upper cassette 1b as one feeding unit. I have. In this example, two feeding units U1 and U2 are mounted and four cassettes are mounted. One upper feed unit U1 is detachably attached to the apparatus main body A, and the lower feed unit U2 is detachably attached to the sheet deck D. Then, the sheets accommodated in the cassette designated and selected are automatically fed to one sheet.

That is, the sheets accommodated in the cassettes 1a and 1b are picked up by a pickup roller 3 serving as a feed rotating body.
After the sheets are separated and fed one by one by the cooperation of the feed roller 4 and the retard roller 5, they are conveyed by the conveying rollers 104 and 105, guided to the registration rollers 106, and formed by the rollers 106. The sheet is fed to the image transfer section of the image forming section C in synchronization with the operation.

In addition to the sheet cassette 1, a manual feed tray 6 is disposed on the side of the apparatus main body A. Sheets on the tray 6 are fed to registration rollers 106 by manual feed rollers 7.

(2) Fixing Device 118 FIG. 2 is a schematic diagram of the fixing device 118 and its peripheral parts.
And a block diagram of a control system.

A) Schematic Configuration of the Fixing Device 118 The fixing device 118 of this embodiment is a heating device of a pressure member driving type and a tensionless type film heating type.

Reference numeral 11 denotes a stay made of a heat-resistant resin whose longitudinal direction is perpendicular to the drawing.

Reference numeral 13 denotes a low-heat-capacity heating element such as a ceramic heater which is disposed and held on the lower surface side of the stay 11 along the length of the stay. The ceramic heater 13 is a low-heat-capacity member having a thin ceramic substrate and a resistance heating element formed along the length of the surface of the substrate as a basic component, and supplies power to the resistance heating element. As a result, the heat is generated and the temperature rises more quickly, and the temperature is controlled and controlled to a predetermined fixing temperature by the temperature control system.

A stay 11 includes the heater 13 described above.
Is a cylindrical (endless belt-shaped) heat-resistant film (fixing film) that is externally fitted to the film. This fixing film 1
The inner peripheral length of the fixing film 12 and the outer peripheral length of the stay 11 including the heater 13 are larger than that of the fixing film 12 by, for example, about 3 mm. To fit loosely.

The fixing film 12 has a total thickness of 4 to reduce the heat capacity and improve the quick start property.
Approximately 0 to 100 μm, the PTFE ・ on the outer peripheral surface of the polyimide film with heat resistance, release properties, strength, durability
It is provided with a coating layer in which a conductive agent is added to a fluororesin such as PFA.

Reference numeral 18 denotes a fixing film 1 between the heater 13 and the fixing film 1.
2 is a fixing film pressing roller as a rotating body for driving the fixing film 12 by forming a fixing portion N which is a press contact nip portion with the core shaft 19 made of aluminum, iron, stainless steel, etc. 3mm thick and 20mm outside diameter made of heat-resistant rubber elastic material with good release properties such as silicon rubber
And a roller portion 18 of Further, on the surface, a coating layer in which a fluororesin is dispersed is provided for the purpose of transporting the sheet P as the recording material and the fixing film 12 and preventing contamination of the toner.

The pressure roller 18 is driven to rotate in the counterclockwise direction as indicated by the arrow by driving the end of the metal core 19 by the motor M2 for driving the fixing device. A rotational force acts on the fixing film 12 by a frictional force between the pressing roller 18 and the outer surface of the fixing film 12 in the fixing unit N due to the rotational driving of the pressing roller 18, and the inner surface of the fixing film 12 is fixed to the fixing unit N. At the same time, the stay 11
Is driven to rotate clockwise as indicated by the arrow (pressing member drive type). In this case, a lubricant such as heat-resistant grease may be interposed between the inner surface of the fixing film 12 and the lower surface of the heater where the fixing film 12 comes into contact with the heater to reduce the sliding resistance.

The stay 11 serves as a fixing film inner surface guide member while keeping the heater 13 thermally insulated.

In the state where the fixing film 12 is rotated by the rotation of the pressure roller 18 and the temperature of the heater 13 is raised to a predetermined fixing temperature and the temperature is adjusted, the fixing film N A sheet P as a recording material on which an unfixed toner image is formed and carried is conveyed and introduced from the image transfer unit R side between the rotating pressure roller 18 and the fixing unit N and the fixing film 12 are nipped and conveyed. As a result, the heat of the heater 13 is applied to the sheet P via the fixing film 12, and the unfixed toner image is heated and fixed on the sheet P surface. The sheet P that has passed through the fixing unit N is conveyed with a curvature separated from the surface of the fixing film 12.

B) Fixing film speed detecting means and drive speed varying means of the apparatus FIG. 3 is a perspective view of the pressing roller 18 of the fixing device 118 and one end of the fixing film 12 as viewed from the upstream side in the sheet conveying direction. is there.

Reference numeral 20 denotes a light reflecting material (reflecting plate) as a marking portion formed on the outer surface of the fixing film 12. The light reflecting material 20 is formed on the outer surface of the fixing film 12 on one end side and on a part outside the paper passing area.

Reference numeral 21 denotes a reflection type sensor, which is mounted above the rotation locus of the light reflecting material 20 at the end of the fixing film on which the light reflecting material 20 is formed.

The light reflecting material 20 of the fixing film 12 rotates with the rotation of the fixing film 12 and passes under the reflection type sensor 21 once per rotation of the fixing film 12. The reflection type sensor 21 detects the reflected light from the reflection material 20 every time the light reflection material 20 passes, and outputs the signal to the CPU.
Sent to 100.

The CPU 100 can calculate the time required for the fixing film 12 to make one rotation from the detection signal and the circumference of the fixing film 12 to determine the rotation speed.

FIG. 4 is a diagram showing changes in the conveying speed of the sheet P as a recording material and the rotation speed of the fixing film 12. According to the experiment, as shown in FIG. 4, there is a correlation between the conveying speed of the sheet P and the rotation speed of the fixing film 12.
Therefore, the actual transport speed of the sheet P can be predicted from the rotation speed of the fixing film 12.

Therefore, the CPU 100 sets the fixing film 1 determined by the input information from the reflection type sensor 21.
When the rotation speed of the fixing film 12 is higher than a predetermined speed, the motor driver 101 controls the speed of the fixing device driving motor M2 to decrease, and the rotation speed of the fixing film 12 determined by the input information from the reflection sensor 21. Is lower than a predetermined speed, the motor driver 101 controls the speed of the fixing device driving motor M2 to decrease.

C) Basic Structure of Marking Section and Detection Sensor FIG. 5 shows a reflected light detection type sensor 21 as a detection sensor.
FIG. 4 is a perspective view showing a positional relationship between the sensor 21 and a light reflecting material 20 provided as a marking portion on the fixing film 12 and having higher reflectance than peripheral films.

When the film 12 rotates and the light reflecting material 20 reaches the detection point of the reflected light detection type sensor 21, the reflectance of the light beam 54 of the sensor 21 increases and the light reflecting material 20
That is, the configuration is such that the marking portion is detected.

FIG. 6 shows an example in which a contact type resistance detection or dielectric constant detection sensor 51 is used as a detection sensor.
The marking portion 20 on the fixing film 12 is coated or vapor-deposited, welded, or bonded to a peripheral film surface with a material (metal or the like) having a different surface resistance value or dielectric constant.

The detecting elements 54a and 54b of the sensor 51 are always in contact with the film 12, and read the difference between the surface resistance value or the dielectric constant of the film portion without the marking portion 20 and the marking portion.

Next, a detailed configuration and a manufacturing method of each type of marking will be described. Each of the marking units 20 in the following various forms is a marking type that performs detection using the reflective sensor 21 as shown in FIG. FIGS. 7A to 7D are enlarged cross-sectional model views of the marking portion 20 on the film 12 of FIG. 5 along the line aa.

[0080] FIG. 7A: The marking section 20 of this example is a reflection member 6 having a higher reflectance than the fixing film 12.
0 is adhered, and a top coat 61 is applied thereon. The reflecting member 60 is formed by adding a high-reflectance powder such as a titanium dioxide powder to a liquid silicone-based or epoxy-based adhesive.
Blending calcium-based artificial pearl powder etc. at a predetermined ratio,
The fixing film is subjected to a primer treatment or a blast treatment or the like, and then applied to a predetermined thickness and dried and cured.

The top coat 61 is obtained by applying a transparent paint containing a fluorine-based resin, and then drying and curing it. The top coat 61 has a structure that does not lower the reflectivity with good light transmittance and has a small contact angle on the surface, so that it is effective for measures against external contamination such as toner and paper powder and improvement in wear durability.

[0082] FIG. 7B: In the marking section 20 of this example, a spherical reflecting member 63 having a higher reflectance than the fixing film 12 is adhered by an adhesive layer 62, and a top coat 64 is applied thereon.

The spherical reflecting member 63 has a diameter D of lead glass or the like.
Are formed in a line on an adhesive layer 62 having a thickness t controlled to 1 / 2D <t <D, and dried by adhesion. Finally, a top coat 61 is applied.

The adhesive is liquid silicone or epoxy, and the fixing film is subjected to primer treatment or blast treatment.

The top coat 61 is formed by applying a transparent paint containing a fluorine-based resin, followed by drying and curing. The effect is the same as in.

[0086] FIG. 7C: In the marking section 20 of this example, a film-like reflecting member 66 having a higher reflectance than the attachment film 12 is adhered by an adhesive layer 65, and a top coat 61 is applied thereon as necessary. You.

The film-like reflecting member 66 is adhered on the adhesive layer 65 with a metal foil such as aluminum.

The adhesive is liquid silicone or epoxy, and the fixing film is subjected to primer treatment or blast treatment.

[0089] (C) of FIG. 7: The marking section 20 of this example is one in which a reflecting member 67 such as a film-like metal having a higher reflectance than the fixing film 12 is directly deposited on the surface of the fixing film on which the base treatment has been performed. There is no adhesive layer.

. Figure 8: The marking section 20 in this example
On the outer peripheral surface of the polyimide fixing film 12, PTFE
Coating layer 70 obtained by adding a conductive agent to fluororesin such as PFA
Is formed by masking a part thereof, and a portion where the masking is not performed and the polyimide fixing film 12 is exposed without the coating layer 70 is used as the marking portion 20.
Polyimide fixing film 12 as marking section 20
The difference in reflectance between the portion and the coat layer 70 is detected by the sensor 21.

[0091] Figure 9: The marking section 20 in this example
A slit 71 is provided in a part of the fixing film 12, a marking member 72 such as a metal film is passed through the slit 71 to form a band, and the ends are adhered to the metal film. Things.

[0092] FIG. 10: Marking section 20 of this example
A hole 57 is formed at an end of the fixing film 12, and a reflection plate 58 having a different reflectance from the fixing film 12 is provided on a surface facing the sensor 21, and the fixing film when the hole 57 passes through the position of the reflection plate 58 is provided. The sensor 21 detects the difference in reflectance with the sensor 12.

D) Specific Control In FIG. 2, reference numeral 24 denotes a first paper detection sensor (sheet detection sensor), which is disposed on the sheet exit side of the registration roller 106. Reference numeral 25 denotes a second paper detection sensor, which is disposed on the sheet exit side of the fixing unit N. Each of the first and second paper detection sensors 24 and 25 has a flag section (not shown), and can detect arrival and passage of the sheet P by the photo interrupters 22 and 23. The detection signal is input to the CPU 100.

[0094] First Sheet Control FIG. 11 is a flowchart showing specific control.

When the power of the image forming apparatus main body is turned on,
The rotation of the pressure roller 18 of the fixing device 118 is started, and the heater 13 is energized to control the fixing unit N to a predetermined temperature.

During this time, the temperature of the pressure roller 18 also rises, so that thermal expansion starts. Therefore, the rotational peripheral speed of the pressure roller 18 increases, and at the same time, the rotational speed of the fixing film 12 also starts increasing as shown in FIG. However, it is naturally slow for a desired speed.

The reflection type sensor 21 always detects the fixing film cycle (rotation cycle).

When the sheet P reaches the first paper detection sensor 24, the photo interrupter 22 turns ON. At this time, the latest fixing film cycle data D1 is
00 picks up.

Then, comparison with the target fixing film cycle T is performed to increase or decrease the fixing driving speed.
In the case of the first sheet, it is necessary to consider the following.

That is, FIG. 12 is a view showing a change in the cycle of the fixing film while one sheet P passes through the image forming apparatus when the speed control is not performed. according to this,
It can be seen that the period of the fixing film becomes longer while the sheet P is in the fixing section N. The rate has been experimentally found to be about 0.8%.

That is, if the fixing drive speed is set based on the above-described fixing film cycle data D1, the fixing film speed actually becomes slower, that is, the sheet speed also becomes slow, and image disturbance is caused. Will happen.

Therefore, a comparison is made with the target fixing film cycle T using the fixing film cycle data D1a obtained by multiplying the fixing film cycle data D1 by a paper coefficient A for correcting an increase in the fixing film cycle due to the passage of a sheet.

D1a = A * D1 (A: paper coefficient, A = 1.008 in this embodiment) Then, by immediately increasing or decreasing the fixing driving speed,
When the first sheet reaches the fixing device 118, the rotation speed of the fixing film 12 can be maintained at a desired speed, so that the transport speed of the sheet P also becomes the desired speed. Therefore, a good image can be obtained.

[0104] Control of the second and subsequent sheets When the first sheet P reaches the paper detection sensor 25,
The photo interrupter 23 is turned on. At this time, the CPU 100 picks up the latest fixing film cycle data D2.

At this time, since the sheet P is in the fixing section N, it is not necessary to multiply the paper coefficient A by the fixing film cycle data D2 as in the case of the first sheet. It may be compared with the film cycle T.

Here, when it is necessary to change the speed of the motor M2, if the speed of the motor M2 is changed immediately at this point, a problem occurs. That is, in many cases, the rear end of the sheet P still exists in the image transfer portion R. At this time, if the speed of the sheet P in the fixing device 118 suddenly changes, the vibration generated by the change is transmitted through the sheet. The image may be blurred.

Therefore, here, the motor speed is not changed immediately, but is changed to the desired speed E seconds after the paper detection sensor 24 is turned off. The E second is set to a time sufficient for the trailing edge of the sheet to pass through the paper detection sensor 24 and then pass through the image transfer unit R. That is, the speed of the motor M2 is changed after the sheet completely passes through the image transfer unit R.

Next, the second sheet is conveyed at the motor speed set here. When the leading edge of the second sheet reaches the paper detection sensor 25, the photo interrupter 23 is turned on. At this point, the CPU 100 picks up the latest fixing film cycle data D3.

Then, the next motor speed is determined by comparing the fixing film cycle data D3 with the target fixing film cycle T, and the motor M2 is changed at the same timing as described above.

Thereafter, the above operation may be repeated.

As described above, in the present embodiment, the driving speed of the pressure roller 18 is controlled by detecting the speed of the fixing film 12 and thereby predicting the transport speed of the sheet P as the material to be heated. Since the control is performed by detecting the time of one rotation of the fixing film, only one marking section 20 such as a light reflecting material provided on the fixing film 12 is required, so that it can be manufactured at low cost. In addition, since there is no need for accuracy between the marking portions, manufacture is easy. In addition, since the signal only needs to be processed once for each sheet, an inexpensive CPU is sufficient.

Also, in the case of the first sheet, that is, the fixing film speed is determined by multiplying the fixing film speed when there is no sheet in the fixing section N by the paper coefficient. The sheet conveyance speed can be controlled before the sheet reaches the apparatus 118, and a stable image can always be obtained. In addition, it can respond to high speed.

(3) Others a) The heating device of the present invention is not limited to the image heating and fixing device of the embodiment, but may be modified, for example, by heating a recording material carrying an image to improve its surface properties (such as gloss). Of course, it can be widely used as a heating apparatus such as a qualifying apparatus, an apparatus for presumed deposition processing, and a sheet processing apparatus for feeding and drying and laminating.

B) The film may be stretched by applying tension between the stretching members.

C) The heating element is not limited to the ceramic heater, but may be, for example, an electromagnetic induction heating member. The film itself may include an electromagnetic induction heating member or an electromagnetic induction heating layer.

D) The pressing member is not limited to the roller body, but may be another rotating body such as a rotating belt.

[0117]

As described above in detail, according to the present invention, in the heating device of the pressure member driving system and the film heating system, the adverse effect due to the fluctuation of the material holding / conveying speed is determined on the upstream side of the heating device. This can be solved without increasing the transport distance of the material to be heated with the processing section, and without increasing the size of the apparatus main body.

Further, in an image forming apparatus provided with the heating device as an image heating and fixing device, it is possible to prevent the image from being disturbed due to a change in the recording material conveying speed due to the thermal expansion of the pressing member.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus.

FIG. 2 is a structural model diagram of a fixing device and a peripheral portion thereof, and a block diagram of a control system.

FIG. 3 is a perspective view of one end of a pressure roller and a fixing film of the fixing device as viewed from an upstream side in a sheet conveying direction.

FIG. 4 is a correlation diagram between the paper conveyance speed and the fixing / fixing film speed.

FIG. 5 is a basic configuration diagram of a marking unit and a detection sensor (part 1).

FIG. 6 is a basic configuration diagram of a marking unit and a detection sensor (part 2)

FIGS. 7A and 7B are examples of various configurations of a reflection type marking unit (part 1);

FIG. 8 is a configuration example of a reflection type marking unit (part 2).

FIG. 9 is a configuration example of a reflective type marking unit (part 3).

FIG. 10 is a configuration example of a reflection type marking unit (part 4).

FIG. 11 is a flowchart showing specific control.

FIG. 12 is a diagram illustrating a change in a fixing film cycle while one sheet passes through an image forming apparatus when speed control is not performed.

[Explanation of symbols]

A: Image forming apparatus main body, B: Image reading scanner unit, C: Image forming unit, D: Sheet deck, 112
Photoreceptor drum, 115 transfer roller, R image transfer unit, 118 fixing device, 11 stay, 12
Fixing film, 13 heater (heating body), 18 pressure roller, M2 pressure roller drive motor, 20 light reflection material, 21 reflection type sensor, 22, 23 photo interrupter, 24, 25 ... paper detection sensor, 100
..CPU and 101 motor drivers

Claims (18)

[Claims] 1. A heating member, a film, and a pressing member which is pressed against and rotated by the heating member across the film,
By introducing the material to be heated conveyed from the processing section on the upstream side to the press-contact nip formed by the heating element and the pressing member with the film interposed therebetween and causing the material to be nipped and conveyed, the heat of the heating element is transmitted through the film. A marking unit provided on the film, a detection unit for detecting the marking unit, and a film speed detection for calculating a rotation speed of the film from a marking unit detection time interval of the detection unit. Means for varying the drive speed of the device; and speed for determining the drive speed of the device for the next heated material using the speed of the film as one heated material passes through the pressure nip. A heating device having control means. 2. The heating device according to claim 1, wherein the marking portion provided on the film is obtained by mixing a high-reflectivity powder with an adhesive at a predetermined ratio, partially coating the film surface, and drying. A heating device, characterized in that: 3. The heating device according to claim 2, wherein the high reflectance powder is titanium dioxide powder or calcium-based artificial pearl powder. 4. The heating device according to claim 1, wherein the marking portion provided on the film is obtained by partially applying an adhesive to the surface of the film, and forming a high-reflectance bead made of glass or the like on the adhesive layer. A heating device characterized by forming and drying a reflection layer in which are arranged. 5. The heating device according to claim 1, wherein the marking portion provided on the film has an adhesive partially applied to the film surface, and a film having a high reflectance such as a metal film is formed on the adhesive layer. A heating device characterized in that the reflection layer is formed and dried. 6. The heating device according to claim 1, wherein a marking portion provided on the film has a different surface resistance, permittivity, or magnetism from the surface of the surrounding film. 7. The heating device according to claim 1, wherein the marking portion provided in the film has a hole in the surface of the film, and the marking member is passed through the hole to carry between the marking members by adhesion or fusion. A heating device, characterized in that it is a heating device. 8. The heating device according to claim 1, wherein the marking portion provided on the film is formed by coating a material having different surface reflectance, surface resistance, dielectric constant, or magnetism on a surface of a surrounding film. A heating device characterized by being formed by vapor deposition or welding. 9. The heating device according to claim 1, wherein the marking portion provided on the film has a top coat layer having a high transmittance as an uppermost layer. 10. The heating device according to claim 1, wherein the detecting means for detecting the marking portion is an optical reflected light detecting means, a contact resistance detecting means, a dielectric constant detecting means, or A heating device characterized by magnetic detection means. 11. A fixedly supported heating element, a film, and a pressing member that is pressed against the heating element with the film interposed therebetween and is driven and rotated, and is formed by the heating element and the pressing member with the film interposed therebetween. The material to be heated conveyed from the upstream processing unit is introduced between the film in the pressure nip portion and the pressing member, and the film is slid and moved to the heating body by the driving rotation of the pressing member. In a heating apparatus for applying heat of a heating body to a material to be heated through a film by sandwiching and conveying a press-contact nip portion together with the material to be heated, the film is made of an insulator and has a coating portion on its outer periphery. The coating member has a lower surface resistance or reflectivity than the surrounding film, and a part of the outer peripheral surface of the film has a marking portion on which no coating is applied, and the detection portion detects the marking portion. It has a step and calculates the rotation speed of the film from the marking unit detection time interval of the detection means, varies the drive speed of the pressing member, and can control the rotation speed of the film within a predetermined range. Heating equipment. 12. A fixedly supported heating element, a film, and a pressure member which is pressed against and rotated by the heating element with the film interposed therebetween, and is formed by the heating element and the pressure member with the film interposed therebetween. The material to be heated conveyed from the upstream processing unit is introduced between the film in the pressure nip portion and the pressing member, and the film is slid and moved to the heating body by the driving rotation of the pressing member. In a heating device that applies heat of a heating body to a material to be heated through a film by sandwiching and conveying a press-contact nip portion together with the material to be heated, a marking part and the marking part are detected on a surface of the film. It has a light reflection type detection means, has a film speed detection means for calculating the rotation speed of the film from the marking part detection time interval of the detection means, and a means capable of changing the driving speed of the apparatus, and one heated material is Pressure welding Using the speed of the film as it passes through the part, has speed control means to determine the drive speed of the device for the next material to be heated, the marking part pierces the film, the sensor facing surface A heating device comprising a reflection member. 13. The heating device according to claim 1, wherein the heating material detecting means upstream of the press-contact nip detects the arrival of the material to be heated in a time period corresponding to one rotation of the film. And a driving speed of the device is determined. 14. The heating device according to claim 1, wherein the film is an endless film. 15. The heating device according to claim 1, wherein the material to be heated is a recording material carrying an image to be heated. 16. The heating apparatus according to claim 1, wherein the upstream processing section is an image transfer section for a recording material. 17. An image forming apparatus comprising: an image forming unit for a recording material; and an image fixing unit that heats and fixes an unfixed image on the recording material conveyed from the image forming unit. An image forming apparatus, comprising: the heating device according to claim 1. 18. The image forming apparatus according to claim 17, wherein the image forming section for the recording material is an image transfer section from the image carrier to the recording material.