JP2001092300A - Fixing device and image-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device, capable of performing copying operation in timing earlier than ordinary timing. SOLUTION: The time taken until finishing waiting is shortened by setting a 1st fixing mode, in which the fixing operation is performed at a fixing speed of 200 mm/sec, when a heating roller reaches 170 deg.C in the initial stage of use, and a 2nd fixing mode in which the fixing operation is performed at a fixing speed of 115 mm/sec, when the heating roller reaches 140 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine of an electrophotographic type or an electrostatic recording type, a laser beam printer, a facsimile or the like, and a fixing device provided in the image forming apparatus. Transfer the visible image formed on the body to the recording material carried on the recording material carrier,
The present invention relates to an image forming apparatus and a fixing device that obtain an output image by performing heat fixing.

[0002]

2. Description of the Related Art As a conventional electrophotographic image forming apparatus of this type, for example, a color image forming apparatus shown in FIG. 3 is known.

The color image forming apparatus shown in FIG. 3 has a digital color image reader at the upper part and a digital color image printer at the lower part.

In the upper reader unit, the original 30 is placed on an original platen glass 31, and the reflected light image from the original 30 obtained by exposing and scanning with an exposure lamp 32 is condensed on a full color sensor 34 by a lens 33. And
A color separation image signal is obtained. The color-separated image signal is amplified by an amplifier circuit (not shown), processed by the same video processing unit (not shown), and sent to a lower printer unit.

In the printer section, the photosensitive drum 1, which is an image carrier, is a large-diameter photosensitive drum having a diameter of 180 mm in this embodiment, and is rotatably supported in the direction of the arrow shown in the figure. Around the photosensitive drum 1, a pre-exposure lamp 11 for initializing the surface of the photosensitive drum 1, and a charger 2 for uniformly charging the surface of the photosensitive drum 1 (a corona charger in this example). An image exposure unit 3 for forming an electrostatic latent image on the photosensitive drum 1 according to image information; a potential sensor 12 for detecting a potential on the surface of the photosensitive drum 1; Four developing units 4C, 4M, 4A, 4B, 4C, 4C, and 4C that store developers (toners) of different colors for developing an image into a visible image.
A fixedly-developed developing device composed of 4Y and 4K, light detecting means 13 for optically detecting the amount of toner on the photosensitive drum 1, a transfer device 5 including a transfer drum 5a as a recording material carrier,
A cleaner 6 and the like for removing the developer remaining on the photosensitive drum 1 are provided.

In the present embodiment, the image exposure means 3 comprises a polygon mirror 3a, a lens 3b, a mirror 3c, etc., and a laser output section modulated by a color image signal for each color separated from the reader section. Laser light E from
Reflected by the polygon mirror 3a, the lens 3b and the mirror 3
c, and is projected onto the surface of the photosensitive drum 1 to form an electrostatic latent image corresponding to a color image signal of each color.

At the time of image formation in the printer section, the photosensitive drum 1 is rotated at a speed of 200 mm / s in the direction of the arrow shown in the figure.
The surface is neutralized and initialized, and then the surface of the photosensitive drum 1 is uniformly charged by the charger 2, and the light image E corresponding to the image signal of each color separated by the image exposure means 3 is converted to a photosensitive drum. The surface is irradiated sequentially to form an electrostatic latent image in a predetermined color order.

Next, a predetermined developing device is operated in the order of cyan (C), magenta (M), yellow (Y), and black (K) in a predetermined developing order, so that the latent image on the photosensitive drum 1 is changed. To sequentially form a resin-based toner image on the photosensitive drum 1. Here, each developing device 4 of the developing device
C, 4M, 4Y, 4K are eccentric cams 24C, 24M, 2
By the operations of 4Y and 24K, a required developing unit is configured to selectively approach the photosensitive drum 1 to perform a developing operation according to the color of the formed latent image.

On the other hand, the recording material cassette 7a, 7b or 7
From c (may be manual feed), pickup roller,
A recording material P such as transfer paper fed by a transport system including a paper feed guide, a paper feed roller, and the like is wound around the transfer device 5 in synchronization with a predetermined timing.

In this embodiment, the transfer device 5 includes a transfer drum 5a having a diameter of 180 mm as a recording material carrier, a transfer charger 5b for transferring a toner image on the photosensitive drum 1 to the recording material, a recording material. And a suction (contact) roller 5g as an opposing pole, an inner corona charger 5d, and an outer corona charger 5e. In the peripheral opening area of the transfer drum 5a which is rotatably supported,
A recording material carrying sheet 5f made of a dielectric material serving as a recording material carrying means is integrally stretched in a cylindrical shape.

In such a transfer apparatus, two recording materials of A4 size and the like are supported, and one recording material of A3 size and the like are supported. As described above, in forming an image on two recording materials, the same image signal is continuously irradiated, a color image is continuously formed on the photosensitive drum 1, and transfer is performed. As the recording material supporting sheet 5f, a dielectric sheet such as a polycarbonate film is used.

The transfer drum 5a is rotated in the direction shown by the arrow in synchronization with the photosensitive drum 1, and the cyan toner image developed by the cyan developing device 4C is transferred to the recording material carrying sheet 5f by the transfer charger 5b in the transfer section. The image is transferred to the recording material carried thereon. The transfer drum 5b continues to rotate as it is, and prepares for transfer of an image of the next color (for example, magenta).

After the transfer of the toner image, the photosensitive drum 1 is cleaned of residual substances such as residual toner by a cleaner 6, and is uniformly charged again by a charger 2.
The laser beam modulated by the next magenta image signal undergoes image exposure as described above.

The magenta latent image is supplied to a magenta developing device 4
M to form a magenta toner image, and this magenta toner image is
Thus, the toner image is transferred onto the recording material carried on the recording material carrying sheet 5f, and the magenta toner image is overlaid on the cyan toner image. The transfer drum 5b continues rotating as it is,
Prepare for the transfer of an image of the next color (for example, yellow).

Subsequently, the above-described process is performed for the image formation and transfer of yellow and black, and when the overlapping transfer of the toner images of four colors is completed, the recording material is subjected to an AC corona discharge for separation. The charge is removed by the charger 5h, then separated from the transfer drum 5a by the action of the separation push-up roller 8b and the separation claw 8a, sent to a fixing device (a heat roller fixing device in this example) 9 by a conveying means, and fixed collectively. The paper is discharged onto the tray 10.

Further, in order to prevent scattering of powder on the recording material carrying sheet 5f of the transfer drum 5a and adhesion of oil on the recording material, the fur brush 14 and the recording material carrying sheet 5f are used. Cleaning is performed by the backup brush 15 facing the fur brush 14, and the backup brush 17 facing the oil removal roller 16 via the oil removal roller 16 and the recording material carrying sheet 5f. Such cleaning is performed before or after image formation, and at any time when a jam (paper jam) occurs.

As shown in detail in the explanatory diagram of FIG. 4, the heat roller fixing device includes a rotatable fixing roller 51 serving as a fixing rotating body, and a heating roller which rotates while being pressed against the fixing roller 51. The configuration includes a pressure roller 52, a release agent application device 53 as a release agent supply / application device, and a roller cleaning device 54.

Inside the fixing roller 51 and the pressure roller 52, a heater 5 of 600 W in this embodiment such as a halogen lamp is used.
6, 57 are provided respectively. The fixing roller 51 and the pressure roller 52 have thermistors 5 respectively.
8 and 59 are disposed so as to be in contact with each other, and by controlling the voltage to each of the heaters 56 and 57 via a temperature control circuit, the temperature of the surface of the fixing roller 51 and the pressure roller 52 is set to 170 ° C. Adjusted to maintain.

The fixing roller 51 has, for example, three layers.
HTV (high temperature vulcanization) type silicon rubber 123 as a lower layer on a core metal 122 having a thickness of 6 mm of aluminum;
45 μm thick fluororubber 125 as an intermediate layer, 20
It is made of a highly releasable silicone rubber 124 having a thickness of 0 μm. The total thickness of these rubbers is 2.4 mm.

The pressure roller 52 also has three layers,
A lower layer 128, an intermediate layer 129, and an upper layer 12 are formed on a core metal 126 having a thickness of 6 mm of aluminum, similarly to the fixing roller 51.
7. The overall thickness of these rubbers is 1.8
mm.

A cleaning device 54 and a release agent coating device 53 are attached to the fixing roller 51. The cleaning device 54 cleans the toner t and the like offset on the fixing roller 51 and removes the toner t. Silicone oil or the like, which is a release agent, is applied to the fixing roller 51 by the mold applying device 53, thereby facilitating separation of the transfer paper (recording material) P from the fixing roller 51 and preventing toner offset. ing.

The cleaning device 54 includes a cleaning web 54a made of a heat-resistant non-woven fabric strip, a pressing roller 54b for pressing the cleaning web 54a against the fixing roller 51, a feeding roller 54c for feeding a new cleaning web 54a, and toner and the like. And a take-up roller 54b that gradually takes up the cleaning web 54a having a reduced cleaning ability. In particular, the offset toner adheres to the thermistor 58 to prevent the thermistor 58 from causing a detection failure. The cleaning device 54 is provided upstream of the thermistor 58 in the rotation direction of the fixing roller 51.

The release agent application device 53 includes an oil tank 53a having a release agent such as silicone oil, pumping rollers 53b and 53c for pumping oil as a release agent from the oil tank 53a, and pumping rollers 53c. 53
b, 53c for applying the oil from the fixing roller 51 to the fixing roller 51, and a blade 53e for controlling the amount of oil applied from the applying roller 53d. The release agent applying device 53 is disposed downstream of the thermistor 58 in the rotation direction of the fixing roller 51 in order to apply the toner. The application roller 53d is a rotatable roller having a surface of sponge rubber coated with silicone rubber.
1 is to apply oil.

In this state, when the transfer paper P is conveyed, the fixing roller 51 and the pressure roller 52 rotate at a constant speed.
The transfer paper P is rotated at a speed of s to apply silicone oil as a release agent to the surface of the fixing roller 51.
1 and the pressure roller 52, pressure and heat are applied at substantially constant pressure and temperature from both the front and back surfaces, and the unfixed toner image is melted and fixed on the paper surface. To form a full-color image. Transfer paper P with fixed image
Is separated from the pressure roller 52 by the lower separation claw 68 and discharged out of the apparatus.

[0025]

As described above, in this type of color image forming apparatus, a color toner image is formed on a recording material P with two to four layers of multi-color toner t. Therefore, the toner to be used is required to have good meltability and color mixing when heat is applied. Therefore, a sharp melt toner having a low softening point and a low melt viscosity is used.

In the above-described heat fixing device, at the time of initial use, that is, for example, when the power is turned on in the morning, the fixing roller and the pressure roller are almost at room temperature (for example, 25 ° C.). And the upper and lower rollers begin to be heated.

After a lapse of a predetermined time, when the roller surface temperature reaches 170 ° C., a fixable state is established, and a copying operation is started. At this time, the image forming apparatus operates at 200 mm / sec.
In order to operate at c, the transfer material also moves within the image forming apparatus at 200 mm / sec, and the roller of the fixing device rotates at about 200 mm / sec to heat, fix, and discharge the transfer material.

The fixing device is operated at 170 ° C. and 200 m
By heating and conveying at m / sec, fixing can be performed with the most appropriate heating amount.

FIG. 2 shows the relationship between the elapsed time and the temperature of the upper roller when the power is turned on.

In FIG. 2, the roller is heated from a room temperature state and the temperature rises.
° C, which indicates that the weight has ended.

FIG. 2 shows the temperature of the upper roller. The lower roller also shows almost the same rise, although the temperature slightly differs depending on the conditions such as the rubber thickness and the core metal thickness.

Normally, the determination of the end of the wait at which copying can be performed at the time of initial start-up is performed based on the temperature of the upper roller.

Further, the reason why the temperature rise of the roller becomes large before the end of the wait is that the heater is controlled so that the roller temperature does not overshoot and go to the high temperature side after the end of the wait.

As can be seen from the above, it has been generally necessary to wait about 8 minutes until the image forming apparatus is ready for copying.

The time depends on the thickness of the rubber, the thickness of the cored bar, the wattage of the heater, and the like. In particular, in order to improve the releasability for fixing a sharp melt toner like a color copier,
When the surface layer has a thick rubber, the rubber layer becomes a heat insulating layer, so that the roller is hardly heated, and it usually takes about 8 minutes to complete the weight.

As a result, there has conventionally been a problem that even when it is desired to make a copy in a hurry, the user has to wait for at least 8 minutes.

An object of the invention according to the present application is to provide a fixing device and an image forming apparatus capable of performing a copying operation at a timing earlier than usual.

[0038]

A fixing device for realizing the object of the invention according to the present application is configured such that a transfer material carrying an unfixed toner image passes through a fixing nip portion, and is thereby heated by heat from a heating unit. A first fixing mode that enables a fixing operation at a first fixing speed when a first fixing temperature is reached in an initial use state, in the fixing device that fixes the unfixed toner image on the transfer material; When a second fixing temperature lower than the fixing temperature is reached, a fixing operation at a second fixing speed lower than the first fixing speed is enabled.
In the fixing mode.

A first configuration of an image forming apparatus that achieves the object of the invention according to the present application has a fixing device having the above configuration in a fixing unit, and transfers a transfer material onto which an unfixed toner image has been transferred to the fixing device. It is characterized in that the toner image is conveyed to fix the unfixed toner image on the transfer material.

A second configuration of the image forming apparatus for realizing the object of the invention according to the present application is the same as the first configuration, wherein the number of continuous image formation in the second fixing mode is limited to a small number. Features.

[0041]

(Embodiment 1) FIG. 1 is a diagram showing an embodiment of the present invention. Note that the mechanical configuration of the image forming apparatus according to the present embodiment is almost the same as that of the conventional example shown in FIGS. 3 and 4, and the description of the same reference numerals is omitted. In this embodiment, the fixing speed and the process speed for image formation can be changed by a control device (not shown).

FIG. 1 is a flowchart showing the operation of this embodiment.

The fixing device in this embodiment normally performs fixing at 170 ° C. and 200 mm / sec as described above.

This is a so-called 6
It is suitable for fixing one of 4g / m ² ~105g / m thickness of ² paper.

Further, in the present embodiment, the fixing device can perform fixing at 170 ° C. and 115 mm / sec. This is, for example, 157 g / m ² or 209 g / m ²
The heat capacity of the transfer material is large, such as m ² , fixing when a film-like transfer material is used, and the amount of heating at 200 mm / sec is insufficient.

For these thick papers and films, the fixing speed is reduced to increase the amount of heating, and a suitable fixing property is ensured.

In this embodiment, at the time of initial use, when the roller is heated from room temperature to start up, copying can be performed at 140 ° C. At this time, the fixing speed is lower than usual 115
mm / sec.

In this state, the aforementioned 64-105 g
/ M ² of paper fixed at 170 ° C with normal settings,
The heating amount equivalent to the fixing heating amount at 200 mm / sec is 1
It is obtained at 40 ° C. and 115 mm / sec.

On the contrary, it is preferable to prohibit copying of a transfer material such as a 157 g / m ² or 209 g / m ² film by detecting the paper thickness of the transfer material.

By doing as described above, the time until the end of the weight can be shortened by about 2 minutes to 6 minutes, and the fixing property is lowered at the same time, although the fixing temperature is low. Thus, it has become possible to secure the fixing property as normal.

However, since the fixing speed is reduced as described above, the so-called productivity of the transfer material fixed and discharged is reduced, and the transfer device in the image forming apparatus shown in FIGS. 3 and 4 is used. When the distance from the fixing device to the fixing device is short, the process speed for forming an image of the image forming device does not match the fixing speed. Therefore, in the present embodiment, the process speed of the image forming device is reduced to 115 mm / sec. I have to.

Next, the operation of the first embodiment will be described below with reference to the flowchart of FIG.

When the power of the apparatus is turned on, heating of the fixing device starts. The rise in temperature is as shown in FIG.

When the temperature of the roller becomes 140 ° C. or higher,
A copy enabled state according to the present invention is obtained. At this time, when performing copying, both the image forming apparatus and the fixing device are 115 mm /
Image formation is performed under the condition of sec.

Until the roller temperature reaches 170 ° C. or higher, copying is possible under such conditions.

When the roller temperature reaches 170 ° C., the weight ends, and image formation is performed at a normal 200 mm / sec.
The fixing operation is performed.

(Embodiment 2) In this embodiment, it is possible to fix at a temperature of 120 ° C. at the time of initial use having a speed of 45 mm / sec, which is even slower than that of Embodiment 1 described above. ~ 105 g / m ² paper with a fixing speed of 45
Fixing is performed at mm / sec.

Under these conditions, the wait end time was further shortened to about 5 minutes and 30 seconds.

Also in this case, the heating amount was the same, and the fixing could be suitably performed.

In this embodiment, the set number of copies is further limited, that is, the normal number of copies that can be copied is 99.
Although heat fixing can be performed in a large number of continuous copies such as 100 sheets or 100 sheets, four sheets are used in this embodiment.

This is because the fixing can be performed at a low temperature, and the continuous fixing cannot be performed due to a decrease in the roller temperature during the continuous copying.

That is, the toner melts and cannot be fixed unless the heating amount exceeds a certain amount. As in the present embodiment, the fixing is started from 120 ° C. and the roller temperature is lowered by continuous fixing. This is because if the temperature is lowered to, the fixing by heating becomes impossible.

The conditions such as the roller temperature dropping from 170.degree. C. to 100.degree. C. due to the continuous fixing shown in the present embodiment are easily changed depending on the configuration of the rollers and the like, and these conditions are only examples. 10 as the fixing point of toner
Although an example in which the temperature is 0 ° C. or higher is shown, since the fixing point of the toner varies depending on the composition of the toner resin, this value is an example.

As described above, according to the present embodiment, it is possible to shorten the time until the end of the weight, and to reliably fix the paper of 64 g / m ^{2 to} 105 g / m ² as the so-called ordinary paper that is normally used. The effect has become great.

The state of initial use has been described, for example, assuming that the room temperature is 25 ° C. in the morning. However, the present invention is not limited to this. This is also effective when the current is heated again.

In this case, in the first embodiment, the temperature is changed from 100 ° C. to 140 ° C., and in the second embodiment, 100 ° C.
Since it takes only time to rise from 120 ° C. to 120 ° C., the effect of not having to wait until the temperature rises from 100 ° C. to 170 ° C. as in the conventional case is equivalent.

The present invention is particularly effective in a full-color image forming apparatus for forming images of two or more colors.

That is, in a full-color image forming apparatus, generally, the fixing property of paper of 64 to 105 g / m ² ,
This is because, unlike a general black-and-white copying machine, the fixing speed is already two or more in order to make the fixing property of the thick paper of 09 g / m ² the same.

Therefore, it is possible to use the low speed side which is already provided, without increasing the cost of the main body.

Conventionally, when performing continuous fixing and the like, when the roller temperature is lowered, fixing may be performed at a slow roller speed in order to secure the fixing property. The fixing and the copying operation can be performed at a timing earlier than usual while ensuring the image quality.

[0071]

As described above, according to the present invention, it is possible to fix at a low speed before the temperature reaches the predetermined temperature at the time of initial use, thereby shortening the time until the end of the wait at the time of initial use. Things become possible.

[Brief description of the drawings]

FIG. 1 is a flowchart showing the operation of the embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a roller temperature and a wait time.

FIG. 3 is a schematic diagram of an image forming apparatus according to a conventional example and the present embodiment.

FIG. 4 is a schematic diagram of a fixing device of the image forming apparatus of FIG. 3; 51 fixing roller 53 pressure roller 56,57 heater 58,59 thermistor P transfer material t toner

Claims (3)

[Claims] 1. A fixing device for fixing an unfixed toner image to the transfer material by heat from a heating unit when a transfer material carrying the unfixed toner image passes through a fixing nip portion. A first fixing mode that enables a fixing operation at a first fixing speed when a first fixing temperature is reached;
A second fixing mode that enables a fixing operation at a second fixing speed lower than the first fixing speed when a second fixing temperature lower than the first fixing temperature is reached. Characteristic fixing device. 2. A fixing device comprising the fixing device according to claim 1, wherein a transfer material on which the unfixed toner image is transferred is transported to the fixing device to fix the unfixed toner image on the transfer material. Characteristic image forming apparatus. 3. The image forming apparatus according to claim 2, wherein the number of continuous images formed in the second fixing mode is limited to a small number.