JPH0274944A - Heat fixing device - Google Patents

Abstract

PURPOSE:To obtain an excellent release property and arbitrary glossiness by constituting a belt of a base material part having excellent mechanical strength such as heat resistance and durability and a surface part consisting of fluoroplastic having the excellent release property to a developer and good surface accuracy. CONSTITUTION:The endless belt consists mainly of two-layered structures consisting of the base material part 101 which has the mechanical strength and assures durability and heat resistance and the surface layer part 102 which has the excellent release property to the developer and has the good surface accuracy. Namely, the material having the mechanical strength to pulling and friction by the rotating motion of the belt and having the heat resistance is selected for the base material part 101 and further the 2nd layer 102 is formed on the surface by coating of the fluoroplastic or sticking of the film thereof as the surface treatment to the base material. The excellent release property to the developer is generated in this way and the degree of the gloss of developing paper is changed by adjusting the surface accuracy of the belt.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a heat fixing device for a copying machine.

[Prior Art] Conventionally, this type of heat fixing device has been designed in such a way that the image surface of color developer paper is brought into contact with an endless belt with good surface precision, and heated while passing between a heat roll and a pressure roll. was there. In such devices, the color developer coated on the color developer paper has a low viscosity and adheres closely to the surface of the belt in a heated state. If the developer paper is separated from the belt at this point, the image will be transferred to the belt because the viscosity of the developer is low, but it is necessary to cool the developer until the viscosity of the developer becomes high enough and then separate the developer paper from the belt. In this case, no image transfer occurs, and the surface of the developing paper becomes smooth and glossy, following the belt surface precision.

[Problem that the invention sought to solve] However, the color developer coated on the color developer paper is extremely sticky when heated and its viscosity is low, so when selecting a belt material, it is important to select a belt material that has excellent mold releasability. In addition, a material with good surface precision is required.

Further, the characteristics of the belt include durability, heat resistance, and good thermal conductivity in consideration of cooling of the color developing paper. Conventional belt materials include silicone rubber or PE.
T-pieces coated with a silicone mold release agent have been sold, but silicone rubber is not durable as a belt, and PE
Although the T base material has good surface precision, it lacks heat resistance, and the silicone mold release agent lacks durability, so it has not been easy to obtain a material that satisfies the required characteristics of the belt material.

The present invention has been made to solve the above-mentioned problems, and has excellent mold releasability with respect to the color developer coated on the color developer paper compatible with the photosensitive and pressure-sensitive paper, and has excellent durability and heat resistance. The objective is to provide a belt with high surface precision and excellent cooling properties.

[Means for Solving the Problems] In order to achieve this object, the belt of the present invention has heat resistance,
It is composed of two layers: a base material with excellent mechanical strength such as durability, and a fluororesin surface part with excellent releasability from color developers and good surface precision.

[Function] According to the present invention having the above configuration, a material having mechanical strength against tension and friction caused by the rotational movement of the belt and heat resistance is selected for the base material portion, and a material having heat resistance is selected for the base material portion. By forming a second layer on the surface by coating with a fluororesin or applying a film as a treatment, excellent mold releasability against a color developer can be produced.

Further, by adjusting the belt surface precision, the degree of gloss of the color developing paper can also be changed.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration of a color image recording apparatus.

The monochrome laser printer 1 is installed on the color image recording device 20, and the paper output tray 12 of the monochrome laser printer 1 is in the position 12a for normal monochrome d printing, while the mask original of the color image recording device is placed in the position 12a. 15R, 1
When printing 5G and 15B (hereinafter also simply referred to as mask originals), they are placed at position 12b.

The color image recording device 20 includes a mask original transport device 21,
A mask original discharge tray 30, a mask original positioning device 31, an exposure device 41, and a storage cartridge 5 for storing an unused photosensitive recording medium (hereinafter also referred to as a capsule sheet) 50.
1. Exposure table 52, winding unit 54 for used capsule sheet 50, cassette 61 for storing color developer sheet 60 for recording color images, pressure developing device 70, heat fixing device 80,
It is composed of a color image paper output tray 63 and the like.

The functions of each part of the color image recording device 20 will be explained in more detail.

First, the main function of the mask original transport device 21 is to transport the set of mask originals 15R, 15G, and 15B in a circular manner so that they can be repeatedly exposed to the capsule sheet 50, and to transfer the exposed mask originals to the device. It means to discharge it outside. In addition to the mask original printed by the monochrome laser printer 1, the mask original conveying device 21 can also manually insert a mask original printed by another mask original production device.

Each part of the mask original transport device 21 includes a guide member 22 that guides each of the set of mask originals 15R, 15G, and 15B from the discharge tray 12b of the monochrome laser printer 1 to the color image recording device 20, A gate 23 for distributing the traveling direction between the alignment device 31 and the discharge tray 3o, a guide section 25 for discharging the exposed mask original from the alignment device 31 to be described later and circulating it, and a mask original. storage areas 26 and 27 for temporarily waiting, and storage areas 26 and 2 for mask originals.
7, an insertion section 29 for manually inserting the mask original, and the like.

Next, the positioning device 31 moves the mask original plate 1 of the − set to
5R, 15G, and 15B are aligned for multiple exposure on the same surface of the capsule sheet 50.

The positioning device 31 has a structure in which a transparent dielectric belt (eg, polyethylene terephthalate, PET film) is processed into an endless shape and stretched between two rotating shafts. At least one shaft of the two rotating wheels is driven by a drive source (not shown) to rotate the belt in the direction of the arrow. Further, both the belt and the rotating shaft unit are configured to be rotatable in a direction perpendicular to the rotational direction of the belt by a second drive source (not shown).

The surface of the front sear belt is charged by a charging device (for example, a corotron), not shown, so that the mask original plate is attracted by electrostatic attraction force.

Further, near the belt in the positioning device 31,
A sensor for alignment is provided and reads alignment marks printed at predetermined positions on each mask original 15.

With the above configuration, the alignment device 31 transports the mask original 15 transported from the mask original transport device 21 to a predetermined position by electrostatic attraction, reads the alignment mark on the mask original, and moves the belt. By moving it together with the mask original, the capsule sheet 50 is aligned to a predetermined position.

The exposure device 41 exposes the capsule sheet 50 through the mask original 15. A linear white light source (hereinafter also simply referred to as a lamp) 42, a reflecting plate 43 for reflecting and condensing the light from the light source, mask original plates 15R, ' 15G, 15
Color separation filters 44R, 44G, 4 corresponding to each of B
4B as the main component, and is reciprocated in the directions of arrows A and B in FIG. 1 by a drive source (not shown).

The photosensitive recording medium (capsule sheet) 50 is, for example, a known one based on a photocurable resin using a photopolymerization initiator as disclosed in JP-A-62-143044. Microcapsules containing a photocurable resin that hardens when exposed to wavelengths of light and cyan, magenta, and yellow dye precursors are coated on a base sheet. Further, the cartridge 51 that houses the capsule sheet 50 and is not exposed to light has an exposure table 52 for bringing the capsule sheet 50 and the mask original 15 into close contact with each other. A cam 53 for pushing up against the positioning device 31 and bringing it into close contact, and a used capsule sheet 50
A take-up roller 54 for winding up the capsule sheet 50, a slack removing device (hereinafter referred to as a buffer) 55 for preventing the capsule sheet 50 from sagging during pressure development and obtaining tension, and a pressure development device to take up the capsule sheet 50 after exposure. A fixed roller 56 for fixing the capsule sheet 50 during development at 70 and a driving roller 57 for winding up the capsule sheet 50 at a constant speed as necessary are provided.

The color developer sheet 60 is a base paper coated with a color developer known in, for example, JP-A No. 58-88739, and is set in a cassette 61 with the side coated with the developer facing downward.

Also, a paper feed roller 62 that is intermittently driven by a drive source (not shown), a paper discharge tray 63 for the developer sheet 60, and a movable guide member that guides the developer sheet 60 from the pressure developing device 70 to the heat fixing device 80. 64.

The pressure developing device 70 receives the exposed capsule sheet 50.
and the color developer sheet 60 are superimposed and the microcapsules are destroyed by pressure to obtain a color image on the color developer sheet.

The heat fixing device 80 promotes the color development of the color image on the color developer sheet 60 and makes it glossy. Presser roller 8 for applying appropriate pressure
3. Consists of an endless belt 84 and the like for fusing and conveying the color developing medium on the color developer sheet.

Next, the operation for obtaining a color image using the color image recording apparatus having such a configuration will be explained.

Based on the principle of color development as described above, first, a mask original plate 15R is created by the monochrome laser printer 1. The mask original plate 15R is a mask original plate in which microcapsules containing a cyan dye precursor are cured in the microcapsules coated on the capsule sheet 50 (the other parts are covered with toner as a light-shielding image). be.

At this time, the discharge tray 12 of the monochrome laser printer 1 is at the position 12b, and the mask original 12R is guided by the guide member 22 into the mask original transport device 21 of the color image recording device 20.

At this time, if the sensor of the alignment device 31 confirms that there is no other mask original in the alignment device 31, the mask original 15R is transported to the alignment device 31 by the gate 23.

Next, the positioning device 31 adsorbs the mask original plate 15R to the transparent endless belt using electrostatic adsorption force and conveys it to the appropriate exposure position, and then transports the mask original plate 15R to the appropriate exposure position.
While the sensor reads the alignment mark printed on the image, a drive source (not shown) adjusts the position to an accurate position.

Next, the capsule sheet 50 is held down by the fixed roller 56, and the cam 53 is rotated by a predetermined angle by a drive source (not shown) to push the exposure table 52 upward, so that the capsule sheet 50 sandwiches the mask original 15R. while closely contacting the positioning device 31.

When the exposure table 52 comes into close contact with the alignment device 31, the lamp 42 is turned on, and the exposure device moves from 41a to 41b to expose the capsule sheet 50 with the red light transmitted through the mask master plate 15H via the color separation filter 44R. Scanning exposure is then performed in the direction of arrow A.

When the exposure operation is completed, the lamp 42 is turned off and the exposure device 41 moves back in the direction of arrow B. At this time, the exposure device 42
The filter cylinder 44 is rotated by a drive source (not shown), and a color separation filter 44G is positioned directly below the lamp 42.

Here, in addition to the positioning mark, the mask master is also printed with a color mark indicating which color the mask master is a color separation mask master, which is read by a sensor at the same time as the positioning operation. In addition, the filter cylinder 44 has 3
It is equipped with a sensor that detects the origin of each type of color separation filter, and if the read color mark does not correspond to the color separation filter 43 of the exposure device 42, the filter cylinder 44 rotates and performs the predetermined color separation. It is now compatible with filters.

While the exposure device 41 moves backward, the exposure table 52 is lowered by the rotation of the cam 53, and the capsule sheet 50 is separated from the alignment device 31 and the mask original 15R.

At this time, pack tension is applied to the capsule sheet 50 at the center of roll rotation of the capsule sheet in the cartridge 51, and when the exposure table rises, the exposure table 50
A length corresponding to the lifting amount of 2 is pulled out from the storage cartridge 51, and when the exposure operation is finished and the exposure table 52 is lowered, the capsule sheet 50 is rewound in a direction to take up the slack.

When the exposure by the mask original 15R is completed and the lowering of the exposure table 52 is confirmed, the endless belt of the positioning device 31 rotates, and the mask original 15R passes through the circulation guide part 25 and is stored in the storage part 26. .

Next, the mask original 15G created by the monochrome laser printer 1 is guided to the alignment device 31 by the guide member 22 and gate 23.

Then, as in the case of the mask original plate 15R, after alignment is performed with respect to the capsule sheet 50, the exposure stage 52
is raised, the capsule sheet 5o and the mask original 15G1 positioning device 31 come into close contact, the lamp 42 is turned on, and exposure with green light is performed. After exposure, the exposure table 52 is lowered, the mask original 15G is guided upward through the circulation guide section 25, the gate 28 is rotated, and the mask original 15G is stored in the storage section 27. The exposure device 41 moves back from the position 41b to the position 41a, and the filter cylinder 44 rotates to position the color separation filter 44B directly below the lamp.

Similarly, the mask original 15B created by the monochrome laser printer is aligned to a predetermined position by the mask original transport device 21 and the alignment device 31, and the capsule sheet 50 is exposed to blue light by the exposure device 42 ( The series of color separation exposures up to this point were referred to as "exposure processing").

Through the above operations, a latent image of a desired color image is recorded on the capsule sheet 5o.

Next, as the exposure table 52 is lowered, the fixed roller 56 is separated, and the drive roller 57 is rotated, so that the capsule sheet 5
0 in the direction of arrow C. At this time, the buffer 55 for taking up the slack of the capsule sheet 50 is at a position 55a, and the movable guide member 64 is at a position 64b. Further, the pressure roller pair 71 of the pressure developing device 70 is spaced apart from each other. Therefore, the microcapsules of the capsule sheet 50 are not damaged or destroyed during the winding operation.

The driving roller 57 stops when the rear end of the latent image on the capsule sheet 50 reaches the position of the pressure roller pair 71 of the pressure developing device 70.

In synchronization with the movement of the capsule sheet 50, the developer sheet 60 is sent out from the cassette 61 by the paper feed roller 62, and stops at a position where the leading end of the developer sheet corresponds to the rear end of the capsule sheet 50. .

Next, a driving device (not shown) presses the pair of pressure rollers 71 of the pressure developing device 70 while rotating in the direction of the arrow. As a result, the capsule sheet 50 is transferred to the color developer sheet 6.
The uncured microcapsules on the capsule sheet 50 are destroyed by the pressure, and a color image corresponding to the latent image on the capsule sheet 50 or a color image on the developer sheet 60 is produced. (This process is referred to as development processing.)

As the pressure developing device 70 rotates in the direction of the arrow, the buffer 55 moves in the direction of the arrow F and absorbs the slack of the capsule sheet 50. When the buffer 55 moves in the direction of arrow F, the movable guide member 64 moves from position 64b to position 64a by a mechanism not shown, and the capsule sheet 50 peels off the tip of the color developer sheet 60, and the heat fixing device I will guide you in the direction of 80.

In the heat fixing device 80, the color developer sheet 60 receives thermal energy from the heater 8 via a rotating heat roller 82 and an endless belt 84, thereby promoting color development of a color image. At the same time, the color developer sheet 60
The binder polymer (binder resin) for fixing to the base paper is thermally melted and has a smoothness corresponding to the surface smoothness of the endless belt, so that the surface of the color developer sheet 60 has a moderate gloss. (this step is followed by coloring and gloss treatment)
).

The color developer sheet 60 that has been subjected to the coloring and gloss treatment is separated by the curvature from the endless belt 84 and is discharged to the paper discharge tray 63.

゛During the above-described series of development and color development gloss processing, the capsule sheet 50 is fixed by the fixed roller 56 as described above, so for the steps before the exposure table 52, the tension of the capsule sheet 50 due to the development in the later steps is It is not affected by changes in

Therefore, while the development process for one screen is being performed, the exposure process for the latent image of another color image can be performed on the exposure table 52.

Incidentally, when it is desired to obtain a plurality of color images from the same mask original plate 15, the mask original plate 15R waiting in the storage section 26 is transferred to the gate 23 in the mask original conveying device 21.
Then, the sheet is guided to the alignment device 31 again, and the same process as the exposure process for the first sheet is performed. The mask originals 15G and 15B are also guided to the alignment device 31 one after another using the storage sections 26 and 27 as soon as the exposure of the previous mask original is completed. The mask original transport device 21 can thus repeatedly circulate the mask original 15 as many times as necessary.

After obtaining the necessary number of color images from the same mask original, the gate 23 rotates and guides each mask original in the mask original transport device 21 to the paper discharge tray 3°.

Furthermore, if by any chance the next combination of mask masters enters from the monochrome laser printer 1 while a series of color images is exposed, the gate 23 guides these mask masters to the output tray 30. do.

Further, the mask original transport device 21 is provided with a manual feed tray 29 for manually loading mask original transport devices produced by other means as described above. However, if there is already another mask original in the mask original transport device 21, a manual feed gate 24 is provided to prevent manual feeding.

FIG. 2 is a detailed structural diagram of the heat fixing device of the color image recording apparatus shown in FIG. 1. The color developing paper developed by the pressure developing device is guided to the inlet chute 91 of the heat fixing device and approaches the abutting portion between the heat roller 82 and the presser roller 83. The heat roller 82 is heated by a halogen lamp heater 81, and the temperature of the heat roll is constantly detected by a temperature detection sensor 85 and adjusted to a constant temperature by a temperature control circuit (not shown). The heater is not limited to a halogen lamp, but may also be a sheathed heater. The press roller 83 is pressed against the heat roller 82 with a constant pressure by a pressure spring 86, and is configured to bring the endless belt 84 and the color developer sheet into close contact. The endless belt 84 is stretched around between the heat roller 82 and the tensioner 87, and the tensioner 87 is pressed in the opposite direction to the heat roller 82 by a tensioner spring 88 in order to keep the tension of the endless belt 84 constant. ing.

When the color developer sheet is conveyed to a certain position in the heat fixing device, the control circuit of the color image recording device reads the amount of movement of the color developer sheet and causes the belt of the heat fixing device to rotate by a drive source (not shown). start.

The color developer sheet is pressurized and heated by a heat roll 82 and a presser roll 83, and the viscosity of the color developer coated on the image side of the color developer sheet decreases, causing it to stick to the belt surface.

If the developer paper is peeled off from the belt while the belt is still hot, the viscosity of the developer is not high enough, and the image will be transferred to the belt, causing defects in the image. In order to prevent this, a sufficient cooling section is provided, and the belt and color developer paper are forcibly cooled using an air cooling fan (not shown). After being cooled, the viscosity of the developer becomes sufficiently high that it can be peeled off from the belt. Color developer sheet is tensioner 87
When reaching the portion , the color developer sheet is curvature separated from the endless belt 84 due to the elasticity of the paper white body.

If the color developer sheet sticks strongly to the belt and is difficult to peel off, it is forcibly removed using a peeling claw 89.

After the developer sheet is torn off, the endless belt 8
4, a felt 90 impregnated with silicone oil is used to clean the belt surface, and the silicone oil is applied to the belt surface. The silicone oil has an auxiliary effect when the color developer sheet is peeled off from the belt.

FIG. 3 shows a cross section of the endless belt 84.

The belt has a two-layer structure, with a base part 101 having mechanical strength, ensuring durability and heat resistance, and a base part 101 having excellent releasability against color developers and improving surface precision. It consists of a good surface layer portion 102.

The properties required for the base material part include mechanical strength against tensile friction because the belt circulates between the heat roll and the tensioner, and the temperature of the heat roll heated to 110°C to 170°C by the heater.
It is said to have good heat resistance because it is heated to about ℃, and also has good thermal conductivity because it cools down within a short time after heating. In order to satisfy these characteristics, metals that can be formed into thin plates that do not undergo work hardening even with a small bending radius are preferred, and stainless steel thin plates are most desirable. If the board is thick, it is difficult to keep the bending radius small, and the rotational drive torque of the belt will also increase, so the base material thickness t2 should be 50 μm or more and 100 μm.
m or less is appropriate.

In addition, when forming the base material with resin, a heat-resistant resin such as polyimide resin or polyamide-imide resin is preferable, and if the heat roll temperature is 120°C or less, a polyethylene terephthalate (PET) film may be used. , considering overheating due to poor temperature control of the heater,
Heat-resistant resin is suitable. In addition, it is better to select a resin film as thin as possible considering thermal conductivity, but considering mechanical strength, the tl should be 25 μm or more and 125 μm or more.
A value of μm or less is appropriate.

When the base material is metal, possible treatments for the surface layer include coating and a resin film coating, and when the base material is resin, a resin film coating is considered. The surface layer material is made of fluororesins such as tetrafluoroethylene resin (PTFE), hexafluoropropylene/tetrafluoroethylene copolymer (FEP), and perfluoroalkoxy resin (PFA), which have excellent mold release properties and surface precision. Also good.

The surface layer thickness is 10 μm or more considering durability and thermal conductivity.
It is preferable to set the range to 00 μm or less.

The surface precision of the belt is directly related to the image surface gloss of the color developer, and the better the smoothness, the higher the gloss. In addition, when coating with fluororesin, the gloss of the image surface can be adjusted by the degree of surface polishing, and the belt surface roughness should be within the range of 0°01a or more and 0.4a or less in terms of center line average roughness (Ra). Depending on the selection, the glossiness of the image surface can be varied from about 40 to about 90.

[Effects of the Invention] As is clear from the detailed description above, by using the belt according to the structure of the present invention, it has excellent mold releasability, durability, and heat resistance against a color developer sheet with high adhesive strength. Since the surface accuracy can be adjusted arbitrarily, a heat fixing device can be constructed which can obtain an arbitrary gloss level.

[Brief explanation of the drawing]

1 to 3 show embodiments embodying the present invention; FIG. 1 is an overall configuration diagram of a color printer;
The figure is a detailed view of the heat fixing device, and FIG. 3 is a sectional view of the belt. In the figure, 8] is a heater, 82 is a heat pipe, 83 is a press roller, and 84 is an endless belt.

Claims (1)

[Claims] 1. A heat roller having a heat source in the center, an endless belt rotating around the heat roller, a tensioner for keeping the tension of the endless belt constant, and a belt facing the heat roller. A heat fixing device equipped with a presser roller that pinches and presses the belt, characterized in that the belt is composed of two layers: a base material portion having heat resistance and durability, and a surface layer portion made of fluororesin. Heat fixing device. 2. The heat fixing device according to claim 1, wherein the surface roughness of the surface layer of the belt is in the range of 0.01a or more and 0.4a or less in terms of center line average roughness (Ra).