JP2682055B2 - Thermal fixing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat fixing device for a copying machine.

[Prior Art] Conventionally, as a thermal fixing device of this type, an endless belt having a high surface precision is brought into contact with an image surface of a color developing paper, and heating is performed while passing between a heat roll and a pressure roll. was there. In such a case, the developer applied to the developer paper has a low viscosity and is in close contact with the surface of the belt when heated. At this point, if the color-developing paper is separated from the belt, the image will be transferred to the belt because the viscosity of the color-developing agent is low, but cool until the viscosity of the color-developing agent becomes sufficiently high.
When the color-developing paper is separated from the belt, the image transfer does not occur, and the surface of the color-developing paper becomes smooth according to the surface accuracy of the belt and gloss can be obtained.

[Problems to be Solved by the Invention] However, since the color developer applied to the color developing paper has a very high adhesiveness when heated and has a low viscosity,
When selecting the belt material, it is necessary to have excellent releasability and surface accuracy. Further, as the characteristics of the belt, it is necessary to have good durability, heat resistance, and good thermal conductivity in consideration of cooling of the color developing paper. Conventional belt materials include silicone rubber or PET coated with a silicone release agent.Silicone rubber is not durable as a belt, and PET base material has good surface accuracy. It has not been possible to easily obtain a material satisfying the required characteristics of the belt material such as no heat resistance and no durability of the silicone release agent.

The present invention has been made to solve the above-mentioned problems, and is excellent in mold releasability with respect to the color developer applied to the color paper compatible with the light and pressure sensitive paper, and has excellent durability and heat resistance. The object of the present invention is to provide a belt having excellent surface characteristics and excellent cooling characteristics.

[Means for Solving the Problems] In order to achieve this object, the belt of the present invention has a substrate portion having excellent mechanical strength such as heat resistance and durability, and excellent releasability from a developer, It is composed of two layers of the surface portion of the fluororesin having high surface accuracy.

[Operation] According to the present invention having the above-described structure, the base material portion is selected from a material having mechanical strength against pulling and friction due to the rotational movement of the belt and having heat resistance, and further, the surface of the base material. As a treatment, a fluororesin coating or a film is attached to form a second layer on the surface, whereby excellent releasability for the color developer can be produced. Also, the degree of gloss of the color-developed paper can be changed by adjusting the belt surface accuracy.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is 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 discharge tray 12 of the monochrome laser printer 1 is installed.
Is at position 12a for normal monochrome printing, while
Mask originals 15R, 15G, 15B of color image recording device (hereinafter,
It is also placed at position 12b when printing a mask original).

The color image recording device 20 includes a mask original transport device 21, a mask original discharge tray 30, and a mask original alignment device.
31, an exposure device 41, a storage cartridge 51 for storing an unused photosensitive recording medium (hereinafter also referred to as a capsule sheet) 50, an exposure table 5
2, a winding portion 54 for the used capsule sheet 50, a cassette 61 for storing a color developer sheet 60 for recording a color image, a pressure developing device 70, a heat fixing device 80, and a color image discharge tray 63.
Etc.

The functions and the like of each unit of the color image recording device 20 will be described in more detail.

First, the main function of the mask original transport device 21 is to circulate and convey the set of mask originals 15R, 15G, 15B so that the capsule sheet 50 can be repeatedly exposed, and the mask original after exposure is used as an apparatus. It is to discharge it outside. Further, the mask original transport device 21 can manually insert a mask original printed by the monochrome laser printer 1 as well as a mask original printed by another mask original creating device.

Each part of the mask original transport device 21 is configured such that each of the pair of mask originals 15R, 15G, and 15B is a monochrome laser printer 1.
A guide member 22 for guiding the color image recording device 20 from the paper discharge tray 12b, a gate 23 for allocating the moving direction of the mask original plate to the alignment device 31 or the paper discharge tray 30, the mask original plate after exposure. Is discharged from an alignment device 31 described later, a guide part 25 for circulating, a storage part 26, 27 for temporarily waiting the mask original plate, a gate 28 for sorting to the mask original plate storage part 26 or 27, It is composed of a manual insertion portion 29 of the mask original plate and the like.

Next, the alignment device 31 uses the set of mask original plates 15
Positioning is performed so that each of R, 15G, and 15B is subjected to multiple exposure on the same surface of the capsule sheet 50.

The alignment device 31 has a structure in which a transparent dielectric belt (for example, a film of polyethylene terephthalate; PET) is processed into an endless shape and is stretched between two rotary shafts. At least one of the two rotary shafts 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 rotating direction of the belt by a second drive source (not shown).

The surface of the belt is charged by an unillustrated charging device (for example, a corotron), and the mask original plate is attracted by an electrostatic attraction force.

Further, in the vicinity of the belt in the alignment device 31,
A sensor for alignment is provided, and the alignment mark printed at each predetermined position on the mask original plate 15 is read.

With the above configuration, the alignment device 31 conveys the mask original 15 conveyed from the mask original conveying device 21 to a predetermined position by electrostatic attraction, reads the alignment mark of the mask original, and moves the belt. By moving the mask sheet together with the mask original plate, the capsule sheet 50 is aligned with a predetermined position.

The exposure device 41 exposes the capsule sheet 50 through the mask original plate 15. Mainly includes a linear white light source (hereinafter also simply referred to as a lamp) 42, a reflective plate 43 for reflecting and condensing light from the light source, and color separation filters 44R, 44G, 44B corresponding to the mask original plates 15R, 15G, 15B. It is reciprocated in the directions of arrows A and B in FIG. 1 by a driving 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 known in JP-A-62-143044, and each of red, green and blue. A microcapsule containing a photocurable resin that cures against light of a wavelength and dye precursors of cyan, magenta, and yellow are applied on a sheet serving as a base material. Further, the cartridge 51, which houses the capsule sheet 50 so as to prevent light exposure, is a capsule sheet 50.
And an exposure table 52 for bringing the mask original plate 15 into close contact with each other, and an alignment device for aligning the exposure table 52 with the mask original plate 15 during exposure scanning.
Cam 53 for pushing up and tightly adhering to 31 and winding roller 5 for winding used capsule sheet 50
4, prevent the capsule sheet 50 from sagging during pressure development,
A slack eliminating device (hereinafter referred to as a buffer) 55 for obtaining tension, a fixed roller 56 for fixing the capsule sheet 50 while the exposed capsule sheet 50 is developed by the pressure developing device 70, and a capsule sheet 50 as necessary. And a drive roller 57 for winding at a constant speed.

The color developer sheet 60 is, for example, a color paper known in JP-A-58-88739, which is coated on a base paper, and the color developer coating surface is set in the cassette 61 so as to face downward. Further, a paper feed roller 62 driven intermittently by a drive source (not shown),
A discharge tray 63 for the developer sheet 60 and a movable guide member 64 for guiding the developer sheet 60 from the pressure developing device 70 to the heat fixing device 80 are provided.

The pressure developing device 70 is for superimposing the exposed capsule sheet 50 and the color developer sheet 60 and destroying the microcapsules by pressure to obtain a color image on the color developer sheet.

The heat fixing device 80 promotes color development of the color image on the color developing agent sheet 60 and gives gloss, and together with the heating roller 82 and the heating roller 82 which incorporates the heater 81 and rotates, the color developing agent sheet.
A pressing roller 83 for applying an appropriate pressure to 60, an endless belt 84 for fusing and conveying the color developing medium on the color developing agent sheet, and the like.

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

Based on the above-described coloring principle, the mask original plate 15R is first created by the monochrome laser printer 1. The mask original plate 15R is a mask original plate in which, among the microcapsules applied to the capsule sheet 50, the toner that is a light-shielding image is placed on the other parts in order to cure the microcapsules having a cyan dye precursor. .

At this time, the discharge tray 12 of the monochrome laser printer 1
12b, and the original mask 12R has a guide member 22
The mask original transport device 21 of the color image recording device 20
Be guided inside.

At this time, when it is confirmed by the sensor of the alignment device 31 that there is no other mask original plate in the alignment device 31, the mask original plate 15R is conveyed to the alignment device 31 by the gate 23.

Next, the alignment device 31 conveys the mask original plate 15R to the appropriate exposure position by adsorbing the mask original plate 15R to the translucent endless belt by electrostatic attraction, and then detects the alignment mark printed on the mask original plate 15R by the sensor. While reading
The drive source (not shown) adjusts the position to an accurate position.

Next, the fixed roller 56 presses the capsule sheet 50,
The cam 53 rotates by a predetermined angle by a drive source (not shown), and the exposure table 52 is pushed upward, so that the capsule sheet 50 is brought into close contact with the alignment device 31 while sandwiching the mask original plate 15R.

When the exposure table 52 comes into close contact with the alignment device 31, the lamp 42
Lights up, and the exposure device performs scanning exposure in the direction of arrow A from 41a to 41b so that the red light exposes the transmitted light of the mask original plate 15R to the capsule sheet 50 through the color separation filter 44R.

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

Here, on the mask original plate, in addition to the alignment mark, a color-based mark indicating what color of the mask original plate is the color separation mask original plate is also printed, and is read by the sensor simultaneously with the alignment operation. In addition, the filter cylinder 44 has 3
If a sensor that detects the origin of each color separation filter of each type is provided and the read color mark does not correspond to the color separation filter 43 of the exposure device 42, the filter cylinder
44 is rotated so as to correspond to a predetermined color separation filter.

While the exposure device 41 is moving back, 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 plate 15R.

At this time, back tension is applied to the capsule sheet 50 at the roll rotation center of the capsule sheet in the cartridge 51, and when the exposure table rises, a length corresponding to the amount of rise of the exposure table 52 is stored in the storage cartridge 51. When the exposure table 52 is pulled out from the inside and the exposure table 52 is lowered, the capsule sheet 50 is rewound in a direction to remove the slack.

When the exposure by the mask original plate 15R is completed and the descending of the exposure table 52 is confirmed, the endless belt of the alignment device 31 rotates and the mask original plate 15R passes through the circulation guide section 25,
It is stored in the storage section 26.

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

Then, similarly to the case of the mask original plate 15R, after the alignment is performed with respect to the capsule sheet 50, the exposure table 52 rises, the capsule sheet 50, the mask original plate 15G, and the alignment device 31 come into close contact with each other, and the lamp 42 is turned on, and exposure is performed with green light. After the exposure is completed, the exposure table 52 descends, the mask original plate 15G is guided upward through the circulation guide portion 25, and the gate 28 rotates to store the mask original plate 15G in the storage portion 27. The exposure device 41 returns to the positions of 41b to 41a, the filter cylinder 44 rotates, and the color separation filter 44B is located immediately below the lamp.

Similarly, the mask original plate 15B created by the monochrome laser printer is aligned at a predetermined position by the mask original plate transporting device 21 and the aligning device 31, and the capsule sheet 50 is exposed to blue light by the exposing device 42 ( The series of color separation exposure up to this point is referred to as <exposure processing>).

By the above operation, the latent image of the desired color image is recorded on the capsule sheet 50.

Next, the exposure table 52 descends, the fixed roller 56 separates, the drive roller 57 rotates, and the capsule sheet 50 is wound in the direction of arrow C. At this time, the buffer 55 for removing the slack of the capsule sheet 50 is at the position 55a, and the movable guide member 64 is at the position 64b. The pressure roller pair 71 of the pressure developing device 70 is separated from each other. Therefore, the microcapsules of the capsule sheet 50 are not scratched or destroyed during the winding operation.

The drive roller 57 stops when the trailing edge 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 color developer sheet 60 is sent out from the cassette 61 by the paper feed roller 62, and stops at a position where the front end of the color developer sheet corresponds to the rear end of the capsule sheet 50. .

Next, the drive roller (not shown) presses the pressure roller pair 71 of the pressure developing device 70 while rotating in the direction of the arrow.
As a result, the capsule sheet 50 is sent in the direction of arrow D while being pressed together with the color developer sheet 60,
The uncured microcapsules on 50 are destroyed by pressure, and a color image corresponding to the latent image on the capsule sheet 50 is developed on the developer sheet 60 (this process is referred to as <development processing>). To).

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 the capsule sheet
Absorb 50 slacks. When the buffer 55 moves in the direction of arrow F, the movable guide member 64 moves from the position 64b to the position 64a by a mechanism (not shown), the capsule sheet 50 peels off the tip of the color developer sheet 60, and the heat fixing device. Take direction 80.

In the heat fixing device 80, the color developer sheet 60 receives heat energy from the heater 81 via the rotating heat roller 82 and the endless belt 84, and color development of the color image is promoted. At the same time, the binder polymer (binder resin) for fixing the color developing medium to the base paper of the color developing agent sheet 60 is melted by heat and has the smoothness corresponding to the smoothness of the surface of the endless belt. , The surface of the color developer sheet 60 has an appropriate gloss (this process is referred to as <color-gloss treatment>).

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

Since the capsule sheet 50 is fixed by the fixing roller 56 as described above during the series of development and color-gloss treatment, the tension of the capsule sheet 50 due to the development of the post-process in the front stage from the exposure table 52. Not affected by changes.

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, in the mask original plate conveying device 21, the mask original plate 15R waiting in the storage section 26 is guided from the gate 23 to the alignment device 31 again. Then, the same process as the exposure process for the first sheet is performed. Storage part 2 for mask original plates 15G and 15B
As soon as the exposure of the previous mask original is completed using 6 and 27,
It guides the alignment device 31 one after another. Thus, the mask master transport device 21 can repeatedly circulate the mask master 15 as many times as necessary.

After obtaining the required number of color images from the same mask original plate, the gate 23 rotates to guide each mask original plate in the mask original plate transport device 21 to the paper discharge tray 30.

If a mask original of the following combination comes in from the monochrome laser printer 1 while exposing a series of color images, the gate 23 guides these mask originals to the discharge tray 30. To do.

Further, the mask original plate transporting device 21 is provided with a manual feed tray 29 for manually loading the mask original plate transporting device created by other means as described above. However, a manual feed gate 24 is provided so that manual feeding cannot be performed when another mask original is already present in the mask original transporting device 21.

FIG. 2 is a detailed structural diagram of the heat fixing device of the color image recording apparatus shown in FIG. The color paper developed by the pressure developing device is guided to the inlet chute 91 of the heat fixing device and approaches the contact portion between the heat roller 82 and the pressing roller 83. The heat roller 82 is heated by the halogen lamp heater 81, the temperature detecting sensor 85 always detects the heat roll temperature, and the temperature control circuit (not shown) adjusts the temperature to a constant temperature. The heater is not limited to a halogen lamp and may be a sheath heater.
The pressing 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 with each other. The endless belt 84 is stretched around so as to circulate between the heat roller 82 and the tensioner 87, and the tensioner 87 is pressed by the tensioner spring 88 in the opposite direction to the heat roller 82 in order to keep the tension of the endless belt 84 constant. ing.

When the developer sheet is conveyed to a certain position of the thermal fixing device, the control circuit of the color image recording device reads the moving amount of the developer sheet and rotates the belt of the thermal fixing device by a drive source (not shown). start. The developer sheet is pressed and heated by the heat roll 82 and the pressing roll 83, and the viscosity of the developer applied to the image surface side of the developer sheet decreases and the developer sheet adheres to the surface of the belt.

If the color-developing paper is peeled from the belt while the belt is still hot, the image is transferred to the belt side and the image is defective because the viscosity of the color-developing agent is not sufficiently high. In order to prevent this, a sufficient cooling section is provided and the belt and the color paper are forcibly cooled by an air cooling fan (not shown). Since the viscosity of the developer after cooling is sufficiently high, it can be peeled off from the belt. Developer sheet is tensioner 87
When it reaches the portion, the developer sheet is separated from the endless belt 84 by the elasticity of the paper itself. If the developer sheet sticks strongly to the belt and is difficult to remove, peel the nail 89
It is configured to be pulled off by force.

After the developer sheet has been peeled off, the endless belt
Numeral 84 is a felt 90 impregnated with silicone oil, which also serves to clean the belt surface and applies silicone oil to the belt surface. 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 is roughly divided into a two-layer structure, has a mechanical strength, a base material portion 101 that secures durability and heat resistance, and has excellent releasability from a color developer, and has a surface accuracy of Good surface layer
It consists of 102. The characteristics required for the base material are:
Since the belt goes around between the heat roll and the tensioner, the mechanical strength against tensile friction is high.
Since it is heated to about 110 ° C to 170 ° C, it has heat resistance, and since it is cooled within a short time after heating, it has good thermal conductivity. In order to satisfy these various characteristics, it is preferable to use a metal that can form a thin plate that does not cause work hardening even with a small bending radius, and a stainless thin plate is most preferable. If the plate thickness is thick, it is difficult to make the bending radius small and the rotational driving torque of the belt also becomes large. Therefore, the base material thickness t ₂ is 50 μm or more 10
0 μm or less is suitable.

When the substrate is formed of a resin, a resin having heat resistance such as a polyimide resin or a polyamide-imide resin is preferable, and a polyethylene terephthalate (PET) film may be used when the heat roll temperature is 120 ° C. or lower. In consideration of overheating due to poor temperature control of the heater, heat resistant resin is suitable. Also, the thickness of the resin film is preferably selected as thin as possible in consideration of thermal conductivity, but t ₁ is preferably 25 μm or more and 125 μm or less in consideration of mechanical strength.

As the treatment of the surface layer portion, when the base material is a metal, a coating and a resin film coating are considered, and when the base material is a resin, a resin film coating is used. Surface material is tetrafluoroethylene resin (PTFE), hexafluoropropylene / tetrafluoroethylene copolymer (FEP), perfluoroalkoxy resin (PFA)
Fluorine resin, etc., has excellent releasability and surface accuracy.

Considering durability and thermal conductivity, the surface layer thickness is 10 μm or more 10
The range is preferably 0 μm or less. The surface accuracy of the belt is directly related to the image surface gloss of the color developer, and the better the smoothness, the higher the gloss. Also, when coating with a fluororesin, the gloss of the image surface can be adjusted by the degree of surface polishing, and the surface roughness of the belt is a center line average roughness (Ra) of 0.
By selecting the range from 01a to 0.4a, the glossiness of the image surface can be changed to about 40 to 90.

[Effects of the Invention] As is clear from the above description, by using the belt having the constitution of the present invention, it is possible to obtain excellent releasability and durability and heat resistance for a developer sheet having high adhesive strength. It is excellent and the surface accuracy can be arbitrarily adjusted, so that a thermal fixing device that can obtain an arbitrary glossiness can be configured.

[Brief description of the drawings]

1 to 3 show an embodiment in which the present invention is embodied. FIG. 1 is an overall configuration diagram of a color printer, and FIG.
FIG. 3 is a detailed view of the heat fixing device, and FIG. 3 is a sectional view of the belt. In the figure, 81 is a heater, 82 is a heat pipe, 83 is a press roller, and 84
Is an endless belt.

Claims (2)

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