JPH0511649A - Fixing deivce - Google Patents

Abstract

PURPOSE:To enable the detection of a transfer material by a sensor installed on the inner peripheral part of a fixing belt-like member. CONSTITUTION:The heating belt 1 of a transparent body is constituted so that it is stretched between a heating roller 2 and a separating roller 3 by a tension roller 4 to be carried, photosensors PS1 and PS2 are installed on the heating/ carrying surface of the transfer material and the circumferential parts of each belt on the downstream of the separating roller 3, and a constitution is adopted so that the carrying actuation of the heating belt 1 is stopped when the carrying trouble of the transfer material under fixing is detected by the photosensor PS1, or when the transfer material winding on a belt surface is detected by the photosensor PS2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device in electrophotography, and more particularly to a fixing device for fixing a color image by eliminating lack of gloss of a color image without causing offset transfer or dirt transfer.

[0002]

2. Description of the Related Art In the fixing process of toner images for electrophotography, heat roller fixing is the most common. In recent years, in electrophotographic processes that handle color images, color reproducibility and glossiness of images after fixing are ensured, and
It is required that the toner be sufficiently melted in order to ensure the transparency when the P transfer material is used. When the melting conditions of polyester toner, which is widely used, are set to the above-mentioned level, it becomes necessary to apply a large amount of low-viscosity silicone oil as a release agent as a prerequisite because of the problem of high temperature offset. There is.

[0003]

As the heating member for the toner image, in addition to the above-described heat roller, there is a fixing device using a belt-shaped member as a heating member for the purpose of controlling the temperature from melting to fixing of the toner. ..

When such a belt-shaped member is used, the conveying distance of the transfer material by the heating member is naturally long, and the transfer material on which the toner image having a particularly high image density is transferred is adhered by the melted toner, so that the fixing material is fixed after fixing. Separation of the transfer material from the belt surface becomes difficult, and the transfer material tends to jam.

Therefore, it is necessary to install a sensor for detecting a jam, but as is well known, the belt-shaped heating member occupies a large space in the structure. Therefore, it is preferable in terms of space to further arrange the sensor on the outer peripheral portion thereof. is not.

As a result of solving and improving this point, the present invention provides
An object of the present invention is to provide a fixing device in which a sensor for jam detection can be installed on the outer peripheral portion of a belt-shaped heating member without taking space.

[0007]

The above object is to provide a fixing device for fixing a toner image on a transfer material by heating and cooling by a moving belt-shaped member, wherein the belt-shaped member is made transparent and the inside of the belt-shaped member is made. This is achieved by a fixing device characterized in that a light detecting means is installed in the.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention is shown in FIGS.

FIG. 1 shows a fixing device according to the present invention. The fixing device is incorporated into an image forming apparatus main body in a state of being housed in an independent container and unitized, and a drive section and a power source section on the apparatus main body side. It is operated by connecting to.

In FIG. 1, reference numeral 1 denotes a heating belt, which is a moving belt-shaped member for fixing, and is stretched between a heating roller 2 and a separation roller 3 by a tension roller 4 urging the heating roller 2. It is circulated in the clockwise direction and conveyed by the drive rotation of.

Reference numeral 5 denotes a roller member that is in pressure contact with the outer peripheral surface of the heating belt 1 around which the heating roller 2 is wound, that is, a pressure roller, which is driven in the counterclockwise direction or driven and rotated at the same speed as the heating roller 2 to heat the heating belt 1. The transfer material is sandwiched between and conveyed.

The pressure roller 5 has a higher hardness than the heating roller 2 and presses the heating belt 1 toward the heating roller 2 side to form a first nip region N1. The second nip region N2 is formed between the heating belt 1 and the heating belt 1 as shown by being located at the downstream side of the conveyance of the heating belt 1 by θ.

Further, the first nip region N1 and the second nip region N1 formed by the pressure contact between the heating roller 2 and the pressure roller 5 are formed.
The corresponding perimeters and angles of the nip region N2 of FIG.
As shown in (b), they are 1 ₁ , 1 ₂ and α ₁ , α ₂ .

The heating roller 2 and the pressure roller 5 have the same outer diameter and each heater H has the same heat generation amount.
1 and H2 are built-in, the temperature of the outer peripheral surface is controlled and managed by the temperature detection of the respective temperature sensors S1 and S2.

Further, F1 and F2 are cross-flow type fans (hereinafter simply referred to as "fans") which are cooling means arranged on the front and back sides of the conveying surface of the heating belt.
Regarding the fan F1, the air sucked from the outside of the apparatus via A and 7B is directly passed to the lower surface of the transfer material through a plurality of slit holes 6A formed in the conveyance guide plate 6, and the fan F1 is
For No. 2, the upper surface of the transfer material is indirectly cooled by spraying on the back surface of the heating belt 1.

Further, the cleaning belts 1A and 5A for cleaning the toner adhered to the outer peripheral surfaces of the heating belt 1 and the pressure roller 5 which wind the heating roller 2 are provided.
Further, an oil impregnated roller 1B is further pressed against the heating belt 1 to prevent the toner from adhering thereto.

The fixing operation of the toner image on the transfer material by the transfer material by the fixing device will be described.

A transfer material having a toner image transferred on its upper surface is indicated by an arrow A.
When it is conveyed into the apparatus from the direction, the front portion is conveyed by being sandwiched between the heating belt 1 and the pressure roller 5 via the carry-in guide plate 8A.

At this time, the transfer material is simultaneously heated from the upper surface and the lower surface by the heating belt 1 and the pressure roller 5 to melt the toner.

That is, the toner on the transfer material is the first toner mentioned above.
In the nip region N1, the heating belt 1 uniformly presses and heats it to bring it into a molten state. However, since the heating is for a relatively short time, the toner image is not disturbed and deterioration of the image quality is suppressed.

After passing through the first nip area N1, the transfer material is heated by the pressure roller 5 from the back surface in the above-mentioned second nip area N2, but is in a molten state because the heating is sequentially performed for a relatively long time. The toner sufficiently penetrates into the transfer material and firmly adheres to it, and there is no risk of offset, so that a toner image with abundant gloss can be obtained.

If the second nip region N2 is made too large, the toner will be excessively melted and the image quality will be deteriorated, and curling and wrinkles of the transfer material will be easily generated, and the load of the drive system will be increased. 3 for the first nip area N1 for
It is desirable that the number is about twice or less.

The transfer material in which the toner has been melted is transferred to the fan F on the lower surface in the process of being transferred along the transfer guide plate 6.
1, the toner image on the upper surface of one side is cooled by the fan F2 and is transferred from the semi-molten state to the next fixed state and separated from the heating belt 1 by the separation roller 3.

The transfer material separated from the heating belt 1 passes through a paper discharge guide plate 8B, a paper discharge roller 9 and a charge eliminating brush BR2.
The electricity is discharged by and is discharged from the direction of the arrow B to the outside of the apparatus main body.

On the other hand, the heating belt 1 from which the transfer material has been separated is neutralized by the static elimination brush BR1, the toner transferred from the transfer material is cleaned by the cleaning roller 1A, and the oil is impregnated by the oil impregnating roller 1B. The transfer material is fixed. On the other hand, with respect to the pressure roller 5, the toner transferred from the heating belt 1 is simultaneously removed and cleaned by the cleaning roller 5A.

The control and management of the fixing temperature in the fixing device are performed as follows.

2 and 3 show the temperature sensors S1 and S.
2 shows a circuit and process for temperature control by means of 2 in which the heaters H1 and H2 are kept in the ON state when the apparatus is "warm up", and the fans F1 and F2,
Both the heating belt 1 and the pressure roller 5 are in the stopped state (OF
Therefore, the pressing action of the pressure roller 5 is released (OFF).
Has been done.

When the "warm-up" is completed and the heating roller 2 and the pressure roller 5 reach predetermined peripheral surface temperatures and the fixing is possible, that is, the "ready" stage, the fixing temperature of the transfer material is kept constant. Therefore, the heaters H1 and H2 are
The ON / OFF state is repeated, and at the same time, the heating belt 1 and the pressure roller 5 respectively start conveying and rotating.

At the "ready" stage, when "printing" is performed in the image forming apparatus, the pressure roller 5 is in the pressure contact state (ON) and the fans F1 and F2 are in the rotation state (ON), so that the transfer material to be carried in is transferred. The conveyance and the fixing operation of the toner image are executed.

During the period from the discharge of the transfer material having been fixed to the transfer of the succeeding transfer material, that is, the "printing interval", the rotation of the fans F1 and F2 is stopped (OFF) and the heating belt 1 is cooled unnecessarily. Suspended.

Further, a temperature sensor S3 is installed on the surface of the heating belt 1 downstream of the conveyance of the fan F1.
When the temperature of the heating belt 1 cooled by 1 and F2 is equal to or higher than the specified temperature exceeding the temperature range suitable for separating the transfer material on which the toner image is fused, the temperature detection signal is output to the circuit shown in FIG. The rotation of the heating roller 2 is interrupted by inputting and the conveyance of the heating belt 1 is automatically stopped.

That is, the temperature of the heating belt 1 must be kept within an appropriate temperature range in order to prevent the occurrence of offset due to low temperature and high temperature when separating the transfer material from the belt surface. Therefore, when the temperature of the heating belt 1 due to the cooling of each fan is equal to or higher than the specified temperature, the conveyance of the transfer material is temporarily suspended to wait for the temperature of the heating belt 1 to decrease, and when the temperature falls to the specified temperature, the temperature of the heating belt 1 decreases again. It is controlled to start moving the heating belt 1 and restart the transfer material transfer. As a result, the transfer material has improved separability and at the same time can fix an image having high gloss.

As shown in FIG. 4, when the temperature of the heating belt 1 becomes lower than the predetermined temperature T1, offset is apt to occur due to the adhesive force of the toner on the surface layer of the toner image. Since it is in a molten state, it is said that this may also cause an offset, and when the temperature of the heating belt 1 exceeds a temperature T3 higher than the temperature T2 ° C., the toner is fused to the belt surface, As a result, the transfer material winds around the heating belt 1 and causes an inseparable trouble. Therefore, the above-mentioned specified temperature is set to be within the range from 130 ° C to 160 ° C as an example, even if T2 is higher than T2. Is desirable.

Further, in order to deal with such a problem that the transfer material cannot be separated from the belt surface or a trouble during the conveyance, the fixing device of the present invention promptly detects the conveyance abnormality of the transfer material and stops the operation of the drive system. We are taking steps to minimize trouble.

That is, as the heating belt 1, for example, a transparent transparent belt-shaped member made of polyimide is used. Further, as shown in FIG. 1, the transfer material carrying surface and the separating roller 3 carrying downstream surface are exposed to light. Photosensors PS1 and PS2 are installed as detection means, and depending on the presence or absence of the transfer material, the sensor is turned on or off by the reflected light from the transfer material.
F is controlled.

Each of the photosensors is composed of a light emitting portion and a light receiving portion, and detects the transfer material outside the heating belt 1 by receiving the reflected light passing through the transparent heating belt 1. Is becoming

When the transfer material on which the toner image has been transferred is not detected by the photosensor PS1 even after a predetermined time has elapsed from the transfer timing, the timer of the control circuit shown in FIG. 2 is activated to operate the heating roller 2 and the pressure roller. Accordingly, the rotation operation of the heating belt 1 is stopped by the rotation of 5.

On the other hand, the transfer material on which the toner image is fixed is not separated from the heating belt 1 but is wrapped around the heating belt 1 and separated by the separation roller 3.
When the transfer material is conveyed to the downstream side, the transfer material is detected by the photosensor PS2 and the conveyance operation of the heating belt 1 is immediately stopped.

Therefore, even if the transfer material is abnormally conveyed, the conveyance is stopped at the initial stage, so that the transfer material is easily treated and prevented from becoming important.

FIG. 5 shows an example of a color image forming apparatus equipped with the fixing device, which comprises an image reading system A, a laser writing system B, an image forming section C and the like.

An original table made of a transparent glass plate or the like is provided above the image forming apparatus, and an original D placed on the original table.
There is a document placing section 11 composed of a document cover or the like for covering the first mirror unit in the main body of the apparatus below the document table.
12, second mirror unit 13, main lens 20, color CCD 23
An image reading system A including the above is provided. The first mirror unit 12 is provided with an exposure lamp 14 and a first mirror 15 and is mounted parallel to the document table and linearly movable in the horizontal direction of the drawing, and optically scans the entire surface of the document D. The second mirror unit 13 integrally includes a second mirror 16 and a third mirror 17, and linearly moves in the same direction in the left and right directions at a speed of 1/2 of that of the first mirror unit 12 so as to always maintain a predetermined optical path length. Of course, the movement of the second mirror unit 13 is the same as that of the first
Similar to the mirror unit 12, it is parallel to the document table.
Document D on a document table illuminated by the exposure lamp 14
Image of the first mirror 15 and the second mirror 1 by the main lens 20.
6. The image is formed on the color CCD 23 through the third mirror 17. After scanning, the first mirror unit 12
And the second mirror unit 13 returns to the original position and stands by until the next copy.

The image data of each color obtained by the color CCD 23 is image-processed and output from the laser writing system B as an image signal.

The image forming section C includes a charger 35, an image exposing section 55, developing units 36Y, 36M, 36C and 36BK, a transfer unit 37, and a separator, which are arranged around the periphery of the photosensitive drum 30 which is an image forming body. 38, a cleaning device 39, a paper feed cassette 40 arranged near the photosensitive drum 30, a conveyor belt 44, and the fixing device according to the present invention.
It consists of 45.

The developing devices 36Y, 36M, 36C and 36BK are provided with a developing device 36Y at the most upstream part of the peripheral edge of the photosensitive drum 30 and a developing device 36BK containing black toner BK at the most downstream part. Well-known color toners and black toners BK contained in the developing units 36Y, 36M, 36C, and 36BK are used, and thus description thereof will be omitted.

When the copy button is pressed, the processes of the image reading system A, the laser writing system B and the image forming section C described above are activated to form a color copy image. That is, when the image signal from the image reading system A is input to the writing system B including the drive motor 31, the polygon mirror 32, and the semiconductor laser, the fθ lens, the correction lens and the like (not shown) under the control of the CPU of the control unit, a copy is made. Start operation. That is, the photosensitive drum 30 rotates clockwise as shown by the arrow, and the charger
35, the yellow (Y) image corresponding to the image of the original D is written by the laser beam by the laser writing system B, and an electrostatic latent image of the Y image is formed. It The electrostatic latent image on the photosensitive drum 30 is subjected to reversal development with Y toner by the developing device 36Y to become a visible Y toner image. That is, the developing device 36
A DC or even AC bias voltage is applied to the developing sleeve containing the Y magnet roll, and non-contact development is performed with a two-component developer that is a developing means to form a Y toner image. The photosensitive drum 30 on which this Y toner image is formed passes under the retracted cleaning device 39,
Subsequently, charging by the charger 35 and laser beam writing of a magenta (M) image by the laser writing system B are performed, and the Y
An electrostatic latent image of a magenta (M) image is formed on the toner image. This latent image is a developing device 36M containing magenta toner.
Is reversely developed to form an M toner image. Subsequently, a cyan (C) toner image and a black (BK) toner image are similarly formed in an overlapping manner.

When the document D is a monochrome image, the developing unit 36
Only BK operates to form a toner image of only black toner BK.

Next, the transfer paper P fed by the paper feed roller 41 one by one from the paper feed cassette 40 containing the transfer paper P which is the transfer material is synchronized with the toner image on the photosensitive drum 30. It is delivered onto the photoconductor drum 30 by an operating timing roller 42. The toner image on the photoconductor drum 30 is transferred to the transfer paper P by the action of the transfer device 37.
After being separated from the photosensitive drum 30 by the separator 38, the toner image is sent to the fixing device 45 via the conveyor belt 44 with the toner image facing upward.

The transfer paper P that has undergone the fixing action in the fixing device 45 is discharged to the outside of the device through the paper discharge roller 46.
On the other hand, the photosensitive drum 30 continues to rotate, and the toner remaining on the surface of the photosensitive drum 30 without being transferred is collected and cleaned by the cleaning device 39 having the cleaning blade 39A or the like that has been retracted, and stands by for the next copy.

For reference, the fixing device of the present invention is composed of the following members as an example.

The heating belt is composed of two layers, a transparent polyimide resin having a thickness of 50 to 75 μm is used as a heat resistant base for the inner layer and a thickness of 50 to 100 μm for the outer layer.
A transparent silicone rubber having a high elasticity and good releasability is used.

Both the heating roller and the pressure roller have a heat-resistant synthetic rubber layer, for example, a silicone rubber layer having a thickness of 2 mm formed on the outer periphery thereof, and 400 W each at the center of a pipe-shaped core metal.
Is used, and especially for the pressure roller, the one that covers the rubber layer with the fluorine tube with a thickness of 50 μm is used.

Foaming sponge rollers made of silicone rubber or urethane rubber are used as the cleaning rollers provided on the heating belt and the pressure roller.

Further, the conveying distance of the transfer material in the fixing device, that is, the distance between the pressure roller and the separating roller is set in the range of 12 to 15 cm.

[0054]

According to the present invention, the transfer material passes between the transparent fixing belt and the transparent fixing belt by installing a sensor for detecting an abnormal conveyance of the transfer material on the inner peripheral portion of the fixing belt member. (PS1) and belt wrapping can be detected (PS2) to prevent toner stains on the sensor due to the arrangement inside the belt peripheral surface, and to make the device compact and to transfer the transfer material. A fixing device that can detect a trouble promptly and take a corrective action without serious trouble is provided.

[Brief description of drawings]

FIG. 1A is a cross-sectional configuration diagram of a fixing device of the present invention,
(B) is an enlarged explanatory view of a main part.

FIG. 2 is a control circuit diagram of a heating temperature in the device.

FIG. 3 is an explanatory diagram showing an operating state of each member in the apparatus.

FIG. 4 is an explanatory diagram showing the relationship between the temperature of the heating belt and the separability of the transfer material.

FIG. 5 is a cross-sectional configuration diagram of a color image forming apparatus including the fixing device of the present invention.

[Explanation of symbols]

 1 Heating Belt 1A Cleaning Roller 1B Oil Impregnation Roller 2 Heating Roller 3 Separation Roller 4 Tension Roller 5 Pressure Roller 6 Transport Guide Plate 6A Slit Hole 7A, 7B Duct 8A Carrying Guide Plate 8B Paper Ejection Guide Plate 9 Paper Ejection Roller H1, H2 Heater S1, S2, S3 Temperature sensor F1, F2 Fan BR1, BR2 Static elimination brush PS1, PS2 Photo sensor 45 Fixing device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location G03G 15/20 102 6830-2H (72) Inventor Yasuhiko Tanaka 2970 Ishikawacho, Hachioji, Tokyo Konica Stocks In-company (72) Inventor Kiyoaki Kawamoto 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Stocks In-company (72) Inventor Tetsuko Omoto Tokyo, Konica-share, 2970 Ishikawa-cho, Hachioji-shi Konica Stock (72) Inventor Toshinori Yamazaki Tokyo 2970 Ishikawa-cho, Hachioji City Konica Stock Company

Claims (1)

Claim: What is claimed is: 1. A fixing device for fixing a toner image on a transfer material by heating and cooling by a moving belt-shaped member, wherein the belt-shaped member is made of a transparent material, and light is emitted inside the belt-shaped member. A fixing device having a detection means.