JPH1165356A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent copying image being free from wrinkles and without blotting irrespectively of the kind of a transfer material by previously performing the surface temp. setting of a heating roller before the image forming processing stage so as to become to the surface temp. of the heating roller in accordance with the kind of the transfer material. SOLUTION: Relating to this device, the kinds of the transfer material used by selecting means 23 are selected before performing the image forming. The transfer material is transported from a paper feeding section where the selected transfer material is charged to the image forming section, the image formation is performed in the universally known method, and then transported to the fixing device. While, the surface temp. of the heating roller 16 is controlled by the first heating means 18 and the second heating means 19 by switching the setting stored in a memory 30 to the surface temp. of the heating roller so that the selected transfer material becomes the excellent output image.

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 and a printer, and more particularly to an image forming apparatus having a fixing device having a selecting means capable of switching a fixing temperature according to each type of transfer material. The present invention relates to a forming apparatus.

[0002]

2. Description of the Related Art Conventionally, a fixing device provided in an image forming apparatus corresponding to a transfer material of A2 size or more is composed of a combination of a heating roller and a pressure roller which is pressed into contact with the heating roller and is driven or interlocked therewith. The unfixed toner image carried on the transfer material is passed and fixed as a permanent image. Inside the heating roller, there are first heating means for heating a substantially central portion in the axial direction of the heating roller, and second heating means for heating both ends in the axial direction of the heating roller,
These two heating means control the surface temperature of the heating roller to a set temperature.

As an example of a method for controlling the fixing temperature, a method for detecting a signal from a first detecting means provided at a position corresponding to the first heating means in contact with the surface of the heating roller and corresponding to the second heating means. Control is performed so that the surface temperature of the heating roller is set by the control means based on a detection signal from the second detection means provided at the position. The size of the transfer material is A1 or A
Even when the transfer roller is different, as in the case of No. 4, the temperature of the pressure roller rises without the transfer material coming into contact with the transfer roller. It is controlled so that it becomes the surface temperature.

Particularly, in an image forming apparatus which handles a large-size transfer material, there is a problem that the transfer material at the time of fixing tends to be wrinkled. Wrinkling can be prevented by forming the crown shape slightly smaller than the diameter of the crown. By adopting such a crown shape, the difference in diameter of the heating roller becomes the difference in the conveying speed of the transfer material, and the transfer material passes through the transfer material so as to be pulled outward, so that the transfer material is flat and wrinkles are prevented.

[0005] However, if the diameter difference between the central portion and the end portion is too large in the above-mentioned crown shape, the difference in the transfer speed of the transfer material also becomes large, and wrinkles can be prevented. The toner image slides on the surface of the heating roller, causing slippage between the surface and the surface of the heating roller, thereby causing blurring of the output image after fixing. The occurrence of wrinkles and the occurrence of bleeding depend on the shape of the heating roller, and the allowable range of the shape of the heating roller is very narrow. This tendency becomes more remarkable as the size of the transfer material increases. For example, if the maximum transfer material size is A1 size, and if the difference between the diameter of the central portion and the diameter of the end portion of the heating roller is 100 microns, an output image without wrinkles and no bleeding on plain paper can be obtained. can get.

On the other hand, there is known an image forming apparatus including a plurality of paper feeding units capable of using a plurality of types of transfer materials having different sizes. Transfer materials of different sizes, such as plain paper, tracing paper, and film material, are loaded into respective paper feed units, and after a desired transfer material is selected, image formation is performed.

[0007]

However, in an image forming apparatus having a plurality of paper feeding units, fixing conditions are different depending on a difference in thickness of transfer material, a kind and a size of a material, and a single heating is required. The shape of the roller makes it impossible to cover everything. That is, if the material and thickness of the transfer material are different, the contraction rate of the transfer material due to heat is different, and
The transfer material in the fixing device slides differently. Furthermore, if the size of the transfer material is different, the degree of heat absorption to the transfer material also differs, causing a difference in the energization time to the heating roller, and the heating roller and the pressure roller expand or contract, causing a difference in diameter between the center and the end. Is no longer constant.

For example, even in the case of a crown-shaped heating roller in which the diameters at both ends are larger than the diameter at the center by 100 microns, if the size of the transfer material is A4 size or A0 size,
If the surface temperature of the heating roller is set to a fixing temperature at which a good fixed image is obtained in A4 size, bleeding occurs in A0 size. In order to obtain a good image in A0 size, it is necessary to make the above-mentioned crown shape a difference of, for example, 200 microns. Conversely, the size is A0
Under the condition to obtain a good copy image in size, A4
Wrinkles occur in size.

In addition, the diameter at both ends is 1 more than the diameter at the center.
Even if the heat roller is a crown-shaped heat roller larger by 00 microns, but the transfer material has the same size but the thickness is different, the surface temperature of the heat roller is set to a fixing temperature that is good when the transfer material is thick. If set, bleeding occurs when the transfer material is thin. In order to obtain a good copy image when the thickness of the transfer material is small, it is necessary to make the above-mentioned crown shape a difference of 200 microns.
Conversely, under the condition that a good fixed image is obtained when the thickness of the transfer material is small, wrinkles occur in a thick transfer material.

Further, the diameter at both ends is 1 more than the diameter at the center.
Even if the transfer roller is made of a different material, that is, the contraction rate of the transfer material due to heat is different even with a crown-shaped heating roller larger by 00 microns, good fixing can be performed on plain paper having a relatively small contraction rate. If the surface temperature of the heating roller is set to a proper fixing temperature, bleeding occurs in the tracing paper having a relatively large shrinkage rate. Conversely, under the condition that a good copy image is obtained when the type of transfer material is tracing paper, wrinkles occur on plain paper.

As described above, the image forming apparatus having the plurality of paper feed units or the type, size,
In an image forming apparatus in which transfer materials having different thicknesses are used, optimum crown shape conditions are required for each transfer material. However, conventionally, there is no other choice but to form and use a crown shape under any one of the conditions.

Particularly, when the shape of the heating roller is formed into a crown shape, extremely accurate dimensional accuracy is required, and it is expensive to improve the processing accuracy. Further, the condition of the pressing force between the heating roller and the pressing roller also needs to be always constant for each machine, and the adjustment work becomes complicated.

The present invention has been made in view of the above problems, and sets the surface temperature of a heating roller in advance before an image forming process so that the surface temperature of the heating roller corresponds to the type of transfer material. Accordingly, it is an object of the present invention to provide an image forming apparatus capable of obtaining a good copied image without wrinkles and without blurring regardless of the type of transfer material.

[0014]

In order to solve the above-mentioned problems, the present invention comprises first heating means for heating a substantially central portion in the axial direction and second heating means for heating both ends in the axial direction. A heating roller, a pressure roller which presses and acts on the heating roller, a first detecting means for detecting a surface temperature of the heating roller heated by the first heating means, and a second heating means. A second detecting means for detecting the surface temperature of the heating roller heated by the first detecting means and the respective detecting temperatures from the first detecting means and the second detecting means are monitored and set in advance to correspond to the respective temperatures. Control means for performing on / off control of the first heating means and the second heating means so as to reach the surface temperature of the heating roller,
An image forming apparatus provided with a fixing device that fixes a transfer material carrying unfixed toner by passing the transfer material between the heating roller and the pressure roller whose temperature is controlled corresponds to each type of transfer material. A plurality of set values of the surface temperature for each of the first and second heating means are stored in the memory in advance, and correspond to the type of the transfer material to be used in the memory. A selection means for selecting a set value is provided, and the control means controls the first and second heating means so that the set value of the surface temperature of the heating roller selected by the selection means is obtained.

The type of the transfer material selected by the selection means is plain paper, tracing paper, or film, and the control means controls the surface temperature of the heating roller according to the selected transfer material. It is characterized by doing.

Further, the image forming apparatus includes a plurality of paper feed units loaded with a plurality of types of transfer materials having different sizes, and the plurality of paper feed units are linked to the selection of the transfer materials by the selection unit. A transfer material is selected, and control is performed such that the surface temperature of the heating roller corresponding to the selected transfer material is controlled by the control unit.

In such a configuration, the type of transfer material to be used is selected by the selection means before image formation.
The transfer material is conveyed from the paper supply unit loaded with the selected transfer material to the image forming unit, an image is formed by a known method, and then conveyed to a fixing device. On the other hand, the setting stored in the storage unit is switched to the surface temperature of the heating roller so that the selected transfer material becomes a good output image, and the surface temperature of the heating roller is controlled by the first heating unit and the second heating unit. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic sectional view of an image forming apparatus 1 according to the present invention. The image forming apparatus 1
A copying machine, a printer, a plotter, or the like is preferably used, and forms a copied image by a known image forming process. For example, as shown in the figure, the image forming apparatus 1 is roughly divided into an image forming unit 2
And a roll paper feeder 3 as a transfer material feeder, and a fixing device 4. The image forming section 1 including the photoreceptor 5 includes a charging corona discharger 6, an image projecting device 7, a developing device 8, a transfer corona discharger 9, a peeling corona discharger 10, a cleaner 11, an eraser lamp around the photoreceptor 5. Numerals 12 are arranged so as to sequentially act on the photoconductor 5 rotating in the direction of arrow A. Although not shown, for example, a document image is digitally read by a scanner, and the read digital image data is output to the image projection device 7.

The roll paper feeding section 3 is provided with a paper feeding device 14 for roll paper 13 used as a transfer material. In the illustrated example, four roll papers 13 can be loaded, and roll papers 13 of different materials and sizes can be loaded. As the type of the roll paper 13, plain paper, tracing paper, film material, and the like can be loaded, and roll paper 13 of different sizes such as A4 to A0 size can be loaded. The temperature setting of the fixing device with respect to the type, size, and thickness of the transfer material loaded in each paper feed unit is preset at the time of factory shipment. Alternatively, although not shown, a setting unit for setting which type of transfer material is loaded in the roll paper feeding unit 3 and which size of roll paper is loaded is provided. It is linked to the operation. Alternatively, a configuration may be adopted in which a detection sensor (not shown) for detecting the size of the roll paper is provided on the transfer material conveyance path to automatically detect the size. Paper feeder 14
A cutter 15 for cutting the drawn-out roll paper 13 to a desired length is disposed to the right of.

Reference numeral 4 denotes a fixing device, which has a heating roller 16 and a pressure roller 17. Pressure roller 17
Act by pressing against the heating roller 16 with an appropriate pressing force, and are driven or interlocked. The heating roller 16 is made of a hollow cylindrical metal material such as aluminum or stainless steel, the surface of which is coated with Teflon, and the surface of the pressure roller 17 is formed of an elastic material such as silicon rubber. Then, the transfer material on which the toner image has been formed by the image forming unit 2 is guided to the fixing device 4 by the conveying unit 26.

FIG. 2 is a schematic view of the fixing device. The heating roller 16 may have a cylindrical shape or a crown shape. A first heating means 1 for heating the surface of the heating roller 16 at a substantially central portion in the axial direction is provided inside the heating roller 16.
8, second heating means 19 for heating the surface of the heating roller 16 at both ends in the axial direction, and first detecting means 20 for detecting the surface temperature of the heating roller 16 at a substantially central portion in the axial direction.
A second detecting means 21 for detecting surface temperatures of both ends of the heating roller 16 in the axial direction; and a heating roller 16 set based on the detected temperatures from the first detecting means 20 and the second detecting means 21. Control means 22 for controlling the first heating means 18 and the second heating means 19 to the surface temperature of the first heating means 18 and the second heating means 19 corresponding to each type of transfer material. And a selection unit 23 for selecting a set value corresponding to the type in the memory 30 corresponding to the type of the transfer material to be used.

The selection means 23 is provided in the control panel 24 of the image forming apparatus 1 for controlling image data such as the number of copies and enlargement / reduction. For example, plain paper, tracing paper, film and the like are displayed. A selection switch (not shown) for selecting a transfer material to be used is provided. The selection unit 23 is connected to the control unit 22 provided in the image forming apparatus main body 1 via the memory 30, and indicates data corresponding to the type of the transfer material to be used together with instructions of various data such as the number of copies and enlargement / reduction. Is stored in the memory 30, and this signal is input to the control unit 22 to control the fixing temperature of the fixing device 4.

The operation of the image forming apparatus 1 will be described.
A transfer material to be used before image formation is selected by a selection switch provided on the selection means 23, and further, the number and size of copied images are selected by the control panel 24. Signals of the type, size, and number of transfer materials are transmitted to the control unit 22, and the first heating unit 18 and the second heating unit are adjusted to the fixing temperature so that the surface temperature of the heating roller becomes a condition stored in the memory 30 in advance. 19 is controlled. First heating means 18
When the surface temperature of the heating roller 16 reaches the set surface temperature by the second heating means 19, the transfer material is supplied from one of the sheet feeding units in which the desired transfer material is loaded in conjunction with the setting means. Is sent to the image forming unit.

The image forming section 2 uniformly charges the surface of the photoreceptor 5 by the charging corona discharger 6,
To form an electrostatic latent image on the surface of the photoconductor by projecting image data from the outside. The formed electrostatic latent image is visualized by the toner in the developing device 8 to form a toner image on the surface of the photoconductor 5. On the other hand, the selected roll paper 13 (transfer material) is conveyed from the roll paper feed unit 3 in conjunction with the operation of the image forming unit 2, and cut into a desired size by the cutter 15. The cut roll paper is sent to the action positions of the transfer corona discharger 9 and the peeling corona discharger 10, and the toner image on the photoconductor 5 is transferred to the roll paper 13 by these actions, and then the roll paper 13 is exposed to light. Peel off the body 5.
Thereafter, the roll paper 13 is transported by a transport belt serving as transport means 26, the toner image is fixed by the fixing device 4 set at a fixing temperature suitable for the fixing condition of the roll paper, and the paper passes through a paper output roller 28. To discharge outside the device. The photoreceptor 5 after the transfer is cleaned by a cleaner 11 to remove the toner remaining on the surface of the photoreceptor 5, and the surface of the photoreceptor 5 is discharged by an eraser lamp 12 to prepare for the next image formation.

In this way, the roll paper 13 carrying the toner image formed by the image forming section 2 has a fixing device controlled to a preset temperature stored in advance in the memory 30 according to its type, thickness and size. You will be guided to 4. The roll paper that has passed through the fixing device 4 has no wrinkles and can obtain a good fixed image without bleeding.

As a result of the experiment, suitable fixing conditions for transfer materials of different materials, sizes, and thicknesses are determined by changing the fixing temperature and determining the degree of shrinkage of the transfer material itself and the expansion and contraction of the heating roller and the pressure roller. Are combined to make the fixed image good, and the respective set temperatures are empirically stored in the memory 30.

In the embodiment, the roll paper feed unit is used as the paper feed unit, but a plurality of paper feed cassettes are provided in the paper feed unit.
Cut paper may be used, and transfer material may be used by hand.

[0028]

According to the present invention, according to the present invention, even when transfer materials having different materials, sizes, and thicknesses are used, the data of the respective fixing conditions corresponding to the individual transfer materials are stored in the memory. The control unit controls the surface temperature of the heating roller of the fixing device so as to satisfy the conditions for obtaining a good fixed image by the selection unit in advance, so that a good fixed image without wrinkles and without bleeding can be obtained. Obtainable.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus according to the present invention.

FIG. 2 is a schematic diagram illustrating a fixing device.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image forming section 3 Roll paper feeding section 4 Fixing device 5 Photoconductor 6 Charging corona discharger 7 Image projection device 8 Developing device 9 Transfer corona discharger 10 Peeling corona discharger 11 Cleaner 12 Eraser lamp 13 Roll paper 14 Paper feeder 15 Cutter 16 Heating roller 17 Pressure roller 18 First heating means 19 Second heating means 20 First detection means 21 Second detection means 22 Control means 23 Selection means 24 Control Panel 25 Control means 26 Transport means 28 Discharge roller 30 Memory

Claims (3)

[Claims] 1. A heating roller provided with a first heating means for heating a substantially central portion in an axial direction and a second heating means for heating both end portions in an axial direction, and operates by pressing against the heating roller. A pressure roller, first detection means for detecting the surface temperature of the heating roller heated by the first heating means, and second detection of the surface temperature of the heating roller heated by the second heating means. Monitoring means, and monitoring the respective detected temperatures from the first detecting means and the second detecting means, and setting the first heating so that the surface temperature of the corresponding preset heating roller is set in advance. And a control unit for performing on / off control of the second heating unit, and fixing the transfer material carrying the unfixed toner by passing the transfer material between the temperature-controlled heating roller and the pressure roller. Fixing device In the image forming apparatus provided with
A plurality of set values of the surface temperature for each of the first and second heating means corresponding to each type of the transfer material are stored in the memory in advance, and the set values are stored in the memory in accordance with the type of the transfer material to be used. A selection means for selecting a set value corresponding to the type in the memory is provided, and the control means controls the first and second heating means so that the set value of the surface temperature of the heating roller selected by the selection means becomes a set value. An image forming apparatus characterized by controlling. 2. The type of the transfer material selected by the selection unit is plain paper, tracing paper, or film, and the control unit controls the surface temperature of the heating roller according to the selected transfer material. The image forming apparatus according to claim 1, wherein: 3. The image forming apparatus includes a plurality of paper feeding units loaded with a plurality of types of transfer materials having different sizes. The image forming apparatus according to claim 1, wherein a transfer material is selected, and the control unit controls the surface temperature of the heating roller corresponding to the selected transfer material.