JP2003015459A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device which most suitably controls a fixing process by changing a roll pressure in accordance with the type of toner for use. SOLUTION: Three press-fixing springs 37a to 37c and press-fixing force switching cams 38a to 38c corresponding to these springs respectively are attached to one side of the fixing device. When a press-fixing release lever 39 is in the perpendicular state, a pair of fixing rolls are in the press-fixing state. When the press-fixing release lever 39 is turned clockwise at 45 deg., an arm 40a in the endmost part rises due to the shape of the left part of the cam 38a, and the press-fixing spring 37a is elongated up to a maximum load in accordance with this rise. Since the arm 40a is separated from a bearing 41a at this time, the spring load dependent upon the arm position is released. When the press-fixing release lever 39 is turned clockwise at 45 deg. furthermore, an arm 40b rises due to the shape of the center part of the cam 38b and is separated from a bearing 41b, and therefore the spring load is released. When the press-fixing release lever 39 is turned clockwise at 90 deg. furthermore, press-fixing is released.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus, and more particularly to a fixing unit used in this color image forming apparatus.

[0002]

2. Description of the Related Art FIG. 19 shows a conventional fixing unit. In the fixing unit shown in the figure, when fixing a matte matte toner to an image, the temperature of the fixing roll 15a is raised and fixing is performed with a small roll pressure. Therefore, one tension spring with a small wire diameter and a low load setting is attached to each side of the crimp spring 37. The non-glossy image with matte toner is suitable for outputting color documents, graphs, etc., and is often used in office printers.

However, in recent years, not only ink jet printers but also electrophotographic printers have been required to have high image quality and photographic image quality. In order to meet this demand, there are electrophotographic printers that use gloss-up type toner (hereinafter referred to as gloss-based toner) as toner, and the color space is increased by increasing the gloss, which is suitable for images such as photographs and graphics. This gloss-based toner is a toner that is fixed at a temperature lower than that of the matte-based toner and with a higher roll pressing force. Further, it is a type of toner in which the nip width between the rolls is increased and the fixing is performed for a long time. For this reason, the structure of the fixing unit is such that two springs having a larger load setting than the fixing unit for matte toner are attached to the left and right. By attaching two springs on one side, assembly becomes easier. Further, since the force is distributed to the two arms, the parts are less likely to be deformed.

Gloss-based toner has a characteristic that if it is fixed in a melted state with a higher pressure, the smoothness of the surface of the toner is increased and the glossiness is increased accordingly. Further, the gloss type toner has a weaker cohesive force between the toners than the matte type toner and is apt to be offset. Therefore, oil must be applied on an oil application roll to improve the releasability.

For the above reasons, comparing the fixing processes of the matte toner and the gloss toner reveals that there are many contradictory conditions. For this reason, when changing the image quality from the matte type to the gloss type with one printer, not only the toner set but also the fixing unit must be replaced. If such replacement is not performed, two electrophotographic printers, a mat type machine and a gloss type machine, must be prepared.

As described above, in the conventional fixing device using the fixing roll 15a and the press roll 15b, the pressure contact force is set according to the specifications of the device. That is, the pressure contact force is set for each fixing device in consideration of the composition of the toner used in the self-fixing device. However, as color printers have become widely used in recent years, it has become desirable to be able to selectively use the above-described matte toner and gloss toner in a single fixing device. Also, such a request has come out.

[0007]

Under such circumstances, printer apparatuses compatible with both matte toner and gloss toner have come out. However, most of them are time adjustments such as adjustment of the conveying force, and are not configured to change the roll pressure stepwise.

It is an object of the present invention to provide a fixing device that optimally controls the fixing process by changing the roll pressure according to the type of toner used.

[0009]

According to the invention of claim 1, a plurality of color toner images are transferred onto a transfer material, and the transfer material is
In a color image forming apparatus that forms an image by being nipped and conveyed by a heating and fixing unit that has a heating roller and a pressure roller that have a heat source on at least one side and are in pressure contact with each other, the heating and fixing unit includes the heating roller and the heating roller. The heating roller and the pressure roller are provided with at least a supporting means for movably supporting one of the pressure rollers on the other side and pressing / separating the pressing roller, and a biasing means for biasing the supporting means in the pressing direction. A color image including a formed image gloss switching means for varying the pressure contact force between the heating roller and the pressure roller so that the glossiness of the image that has been heated and fixed by passing between The above object can be achieved by providing a forming apparatus.

According to the second aspect of the invention, the oil supply amount control means for controlling the oil supply amount supplied to the oil application roller is interlocked with the formed image gloss switching means of the first aspect, and the oil of the oil application roller is interlocked. Control supply. In the invention according to claim 3, as the formed image gloss switching means according to claim 1, the pressure contact force between the heating roller and the pressure roller is made variable by the switching lever.

According to the fourth aspect of the invention, the pressure contact force between the heating roller and the pressure roller is made variable by the drive control means for controlling the drive means such as the motor. According to the fifth aspect of the invention, the toner images of a plurality of colors are transferred onto a transfer material, and the transfer material is provided by a heating and fixing means having a heating roller and a pressure roller which have a heat source on at least one side and are in pressure contact with each other. In a color image forming apparatus that nips and conveys to form an image, the heating and fixing unit includes a supporting unit that movably supports one of the heating roller and the pressure roller to the other and press-contacts / separates, and the supporting unit. A plurality of urging means for urging the pressure roller in the pressure contact direction, and by selectively restricting the action of the plurality of urging means on the supporting means, the pressure contact force between the heating roller and the pressure roller is made variable. The above-mentioned problems can be achieved by providing a color image forming apparatus characterized by including a pressure contact force varying means.

Here, the plurality of urging means are specifically three crimping springs described later and crimping force switching cams corresponding to them. According to the invention of claim 6,
The oil supply amount control means for controlling the oil supply amount supplied to the oil application roller controls the oil supply amount of the oil application roller in cooperation with the pressure contact force varying means of the fifth aspect. Further, in the invention according to claim 7, as the pressure contact force varying means according to the fifth aspect, the pressure contact force between the heating roller and the pressure roller is varied by the switching lever.

According to the present invention, the pressure contact force between the heating roller and the pressure roller is made variable by the drive control means for controlling the drive means such as the motor. The ninth and tenth aspects of the present invention show modified examples in which the pressure contact force between the heating roller and the pressure roller of the fixing unit is driven by the drive means.

That is, in claim 9, the drive control means makes the pressure contact force between the heating roller and the pressure roller variable based on the information detected by the detection means for detecting the type of the transfer material. Here, the type of transfer material is, for example, information such as plain paper or thick paper.

Further, in claim 10, it is assumed that image information is transmitted from the host device connected to the color printer to the color printer. The image information received by the printer includes image gloss information, and based on this image gloss information, the drive control means makes the pressure contact force between the heating roller and the pressure roller variable.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 shows an example of a so-called tandem type color printer. This printer device is connected to a host device such as a personal computer by a cable (not shown).

The internal structure of the printer device 1 shown in FIG. 1 is composed of an image forming section 2, a double-sided printing transport unit 3, and a paper feeding section 4. Here, the image forming unit 2 has a configuration in which four image forming units 5 to 8 are arranged side by side, and magenta (M), cyan (C), and yellow (Y) from the right side to the left side of the drawing. , And black (K) in that order. Among these, magenta (M), cyan (C),
The yellow (Y) image forming units 5 to 7 are configured to perform color printing by subtractive color mixing, and the black (K) image forming unit 8 is used for monochrome printing.

Here, each of the image forming units 5 to 8 described above.
Are composed of a drum set C1 and a toner set C2, respectively, and have the same structure except for the developer housed in the developing container. Therefore, the configuration will be described by taking the image forming unit 7 for yellow (Y) as an example. Drum set C1
Includes the photoconductor drum 9, the charger 10a, and the cleaner 10e.
The print head 10b is disposed above the drum set C1. The developing roller 10c and toner are stored in the toner set C2.

The peripheral surface of the photosensitive drum 9 is made of, for example, an organic photoconductive material. In the vicinity of the peripheral surface of the photosensitive drum 9, a charger 10a, a print head 10b, and a developing roll 10 are provided.
c, a transfer device 10d, and a cleaner 10e are sequentially arranged. The photoconductor drum 9 rotates in the direction of the arrow, and first, the peripheral surface of the photoconductor drum 9 is uniformly charged by the charge applied from the charger 10a. Then, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 9 by optical writing based on the print information from the print head 10b, and a toner image is formed by the developing process by the developing roll 10c. At this time, the toner image formed on the peripheral surface of the photosensitive drum 9 is the toner set C2.
It depends on the yellow (Y) color toner stored in. In this way, the toner image formed on the peripheral surface of the photosensitive drum 9 is transferred to the transfer device 1 as the photosensitive drum 9 rotates in the arrow direction.
It reaches the position of 0d, and is transferred onto the sheet moving below the photosensitive drum 9 in the arrow direction.

On the other hand, the sheet is transported by the sheet cassette 11, the standby roll 12, the transport belt 13, the driving roll 14 and the like which constitute the above-mentioned sheet feeding section 4, and the sheet feeding roller 11a.
By the rotation of, the paper carried out from the paper feeding cassette 11 is sent to the standby roller pair 12, and further, is sent on the conveyor belt 13 at the timing corresponding to the toner image, and reaches each transfer device 10d. Then, the toner image is transferred in each of the transfer devices 10 d, and the sheet on which the toner image is transferred moves on the conveyor belt 13 in the direction of the arrow in accordance with the movement of the conveyor belt 13, and is subjected to heat fixing processing in the fixing unit 15. .

Further, not only the yellow (Y) toner image but also the magenta (M) and cyan (C) toner images are transferred onto the upper surface of the paper, and printing of colors according to the subtractive color mixture described above is performed. Is done. The above-mentioned paper includes not only the paper carried out from the paper feed cassette 11 but also the paper supplied from the MPF tray 16. In this case,
The paper is carried in by the paper feed roller 16a, and the printing process is performed through the above-mentioned path.

The fixing unit 15 includes a heating roll 15a (hereinafter referred to as a fixing roll) and a press roll 1.
5b and the oil coating roll 15c, the sheet is sandwiched and conveyed between the fixing roll 15a and the press roll 15b, and the toner images of, for example, a plurality of colors transferred to the sheet are melted and thermally fixed on the sheet. . The oil applying roll 15c has a function of applying a releasing oil to the peripheral surface of the fixing roll 15a and removing the toner remaining on the fixing roll 15a. The sheet on which the toner image is fixed by the fixing unit 15 is moved upward through the switching flap 17.
Alternatively, the sheet is conveyed leftward on the paper surface. Then, the paper is guided to the paper discharge unit 21 via the paper discharge roll pair 20.

On the other hand, the double-sided printing transport unit 3 is detachably attached to the apparatus main body and is a unit to be mounted when double-sided printing is performed by the printer apparatus 1 of the present embodiment. Pairs 18a to 18e are provided. For double-sided printing, the switching flap 1
7, the sheet is once fed upward, and when, for example, the trailing edge of the sheet reaches the conveyance roll 19, the conveyance of the sheet is stopped,
Further, the paper is conveyed in the reverse direction. By this control, the paper is carried into the paper carrying path of the double-sided printing carrying unit 3 set at the position indicated by the dotted line, and the reverse carrying roller pair 18a to 18a.
The paper is fed in the reverse direction by 18e, and the standby roller pair 1
2, and as described above, the toner image is sent to the transfer portion at the same timing, and the toner image is transferred to the back surface of the paper.

FIG. 2 is an external perspective view of the printer device 1 shown in FIG. The printer device 1 shown in FIG. 1 is composed of an upper part 22 and a lower part 23 of the device,
An operation panel 33 is disposed on the above, and a print sheet discharging section 21 is also formed on the upper surface thereof. Operation panel 33
Is composed of a key operation unit 33a in which a plurality of keys are arranged, and a display unit 33b such as a liquid crystal display which performs display based on display information output from the CPU 30 of FIG. 3 described later. In addition, the rotation of the paper discharge roll 20 outputs the print paper created by the image forming unit to the paper discharge unit 21, and the print paper is sequentially stacked on the paper discharge unit 21.

Further, a front cover 24 that can be opened and closed is provided on the front surface of the lower portion 23 of the apparatus main body. The front cover 24 is opened for jam processing and maintenance, for example. Further, the loading and unloading of the oil application roll described later is also performed by pulling out the oil application roll from the front side of the printer device 1.

FIG. 3 is a circuit block diagram of the printer device 1 having the above configuration. 3, the circuit block includes an interface controller (hereinafter referred to as I / F controller) 26, a printer controller 28, a printer printing unit 29, a CPU 30, a ROM 31, an operation panel 33, and an EEPROM 32. The I / F controller 26 converts the print data supplied from the host device into bitmap data and expands it in the frame memory 27. In the frame memory 27, a storage area is set for each of magenta (M), cyan (C), yellow (Y), and black (K), and data of each color is expanded in the corresponding area.

The data expanded in the frame memory 27 is output to the printer controller 28, and is output to the printer printing unit 29 under the control of the CPU 30. At this time, the data of each color of magenta (M), cyan (C), yellow (Y), and black (K) is supplied to the corresponding print head 10b of FIG.

The system program of this example is stored in the ROM 31, and the CPU 30 performs processing in accordance with this system program. FIG. 4 is a vertical sectional view of the fixing unit of this embodiment. The feature of the fixing unit of the present embodiment is that three pressure contact springs 37a to 37c and the corresponding pressure force change cams 38a to 38c having the shape shown in FIG. 5 are provided on one side. Crimping force switching cams 38a to 38c
Are integrated in parallel. Note that FIG. 5 is a side cross-sectional view taken along the cross-sections A, B, and C of FIG.

6 to 9 show an operation example of the fixing unit of this embodiment. FIG. 6A shows a state in which the pressure release lever 39 is vertical. At this time, the crimp release lever 39 is in the crimped state. In this state, the crimp springs 37a to 37
All of c transmit the load of the designated length to the fixing roll 15a. At this time, the total spring load matches the maximum spring load. Further, in this state, the pressure-bonding force is maximum, which is suitable for a high gloss image at the time of fixing the gloss type toner. In addition, since the roll nip width is maximized, it is also suitable for glossy toner fixing of thick paper that is easily offset at low temperature.
Note that FIG. 6B is a side cross-sectional view of FIG. 6A taken along a section A. Further, FIG. 6C is a side sectional view of FIG.

FIG. 7A shows the pressure release lever 39 45.
It shows a state where it is fixed by turning it to the right. In this state, the leftmost shape of the crimping force switching cam 38a raises the endmost roll support arm 40a, and the crimping spring 37a is extended to the maximum load in conjunction therewith. At this time, since the roll support arm 40a is separated from the bearing 41a, the spring load due to this arm position is released. As a result, the total spring load becomes ⅔ of the maximum spring load.
Incidentally, this state is suitable for a low gloss image at the time of fixing the gloss type toner. Incidentally, FIG. 7B is a side cross-sectional view of FIG. 7A taken along a cross section A.

Further from FIG. 7A, the pressure release lever 39
When is rotated 45 degrees to the right and fixed, the state shown in FIG. In this state, the crimping force switching cam 38
The shape of the central portion of b causes the roll support arm 40b to rise and separate from the bearing 41b, whereby the spring load is released. The total spring load is 1/3 of the maximum spring load. In this state, it is suitable for fixing the matte toner, which requires less pressure bonding force. Note that FIG. 8B is the same as FIG.
It is the sectional side view which saw and cut | disconnected by the cross section B.

Further from FIG. 8A, the pressure release lever 39
9 is rotated by 90 degrees to the right and fixed (that is, rotated by 180 degrees from the crimped state to the right) and fixed.
The state shown in FIG. Since the bearing 41c that supports the fixing roll 15a is fixed to the innermost roll fixing and supporting arm 40c, when the roll fixing and supporting arm 40c is lifted by the crimping force switching cam 38c, the fixing roll 15a is also moved upward in conjunction with this. Go up,
Crimping is released. The pressure release state of FIG. 9A is a state used during transportation or JAM paper processing. Incidentally, FIG.
(B) is the figure which saw the same figure (a) by the cross section C.

In the above description, the pressure release lever 3
9 is the operation when changing the roll crimping force shown in Figs.
The printer main body 1 may be operated without opening the roof, and the roof may be opened and operated only when the pressure release state of FIG. 9 is set. All the operations of the pressure release lever 39 are performed when the roof is opened. The exterior of the printer main body 1 may be devised, for example, by installing a window in which the pressure-bonded state can be confirmed when the roof is closed.

In the above description, the number of pressure springs to be installed is three.
However, the number of pressure-bonding springs may be set to one or two, and the pressure-bonding force may be changed by adjusting the load based on the tension length of the spring. As described above, in this embodiment, a plurality of pressure-bonding springs are installed in the fixing unit, and the fixing roll pressure can be changed by operating the cam and the arm depending on the position of the pressure-release lever. Therefore, the fixing unit for fixing the gloss toner and the matte toner can be shared. Moreover, the user can switch the image glossiness by a simple lever operation. Further, even if an image failure due to the offset occurs, the user can handle it by operating the lever. Further, by selecting the pressure force and the roll temperature suitable for the image and toner, the life of the fixing roll can be extended. Further, by installing a plurality of springs, the assembly is facilitated and the force of the springs is distributed to each roll support arm, so that the parts of the arm and frame are less likely to be deformed. <Second Embodiment> In this embodiment, control different from that of the first embodiment will be described. The feature of this embodiment is that the arm is provided with an oil coating roll bearing pedestal.

The operation of the fixing unit of this embodiment will be described below with reference to FIGS. FIG. 10 shows the state of the fixing unit when the gloss type toner is set. As described above, since the gloss type toner has a low toner cohesive force and is apt to be offset, the peelability must be improved by oil. The oil application roll 15c is in contact with the fixing roll 15a with an appropriate load by the oil application roll pressure contact spring, and is rotated by being driven by the fixing roll 15a. In this state, the oil application roll 15c supplies oil in an amount suitable for the gloss type toner.

In FIG. 11A, the pressure release lever 39 is
It is in a state of being rotated 5 degrees. This state is an intermediate state between the state of FIG. 10 and the state of FIG. 12 described later.
In this case, it is possible to extend the life of the fixing unit by performing control such that a large amount of oil is supplied for the gloss type toner and an excessive amount of oil is not supplied for the mat type toner.

The pressure release lever 39 is shown enlarged in FIG. 11 (b). In order to show the position of the pressure release lever 39 in the printer body, FIGS. 14 and 15 are external views of the printer apparatus of this embodiment. FIG. 14 is a diagram showing a state in which the front cover 24 of FIG. 2 is opened. In addition, FIG. 15 is a front cover 24 in FIG.
It is a figure showing the state where main part upper part 22 was opened.
As shown in FIGS. 14 and 15, the pressure release lever 39 is located in front of the oil application roll 15c. When the pressure release lever 39 shown in FIG. 11B is turned counterclockwise, the state shown in FIG. 14 is obtained. On the other hand, when the compression release lever 39 is raised, the state shown in FIG. 15 is obtained. When the pressure release lever 39 in FIG. 15 is raised, the blade of the pressure release lever 39 interferes with the oil application roller unit 15c and cannot be removed.

FIG. 12 shows a state in which the matting toner is used in which the pressure release lever 39 is rotated 90 degrees. Since the offset is less likely to occur when the matte toner is used as compared with the gloss toner, it is possible to fix the oil in a smaller amount than the gloss toner. Therefore, in this state, the oil application roll bearing pedestal 44 installed on the roll support arm 40 raises the oil application roll bearing 43, so that the pressure contact force between the oil application roll 15c and the fixing roll 15a is weakened. . As a result, the amount of oil supplied from the oil application roll 15c can be reduced, and fixing can be performed with an oil amount suitable for matte toner. When image oil stains occur when the oil application roll 15c is new, the amount of supplied oil may be reduced by selecting the state in which the pressure release lever 39 of FIG. 12 is rotated 90 degrees.

FIG. 13 shows a state in which the pressure release lever 39 is rotated 180 degrees. In this state, the fixing roll 15a and the press roll 15b are released from the pressure contact. At this time, the oil coating roll bearing 43 is further raised in association with the roll support arm 40 and the oil coating roll bearing pedestal 44, and the oil coating roll 15c is completely separated from the fixing roll 15a. This state is suitable when the printer body 1 is transported, and by removing the load from the outside, it is possible to reduce excess oil when new.

As described above, in this embodiment, the oil application roll bearing pedestal is installed on the fixing roll support arm, and the pressure contact force of the oil application roll is made variable by operating in conjunction with the fixing roll pressure release lever. As a result, the amount of oil suitable for the gloss type toner and the matte type toner can be supplied, so that the oil roll unit can be shared. Further, since the oil application roll is separated from the fixing roll when the pressure is released, it can be packed in the fixing unit during transportation. <Third Embodiment> In the above-described embodiment, the pressure contact between the pair of fixing rolls is manually performed by operating the pressure release lever, but this operation may be performed automatically. This embodiment deals with the case where the pressure contact of the fixing roll pair is automatically performed.

In the conventional fixing unit, pressure is applied to the roll by using arms or the like on both sides. In this conventional fixing device, springs are hooked on the arm portions on both sides to apply pressure as a method of pressing the upper and lower rolls. However, it was difficult to make the nip uniform by the pressure bonding by the arm method due to the variation of the spring. Especially when using gloss toner, it is necessary to make the nip uniform in order to make the image uniform. Further, in the past, since the fixing properties of plain paper and thick paper are different, fixing speed and fixing temperature have been changed.

FIG. 19 shows a conventional fixing unit. When matte toner is used in this fixing unit, the fixing roll 15a and the press roll 15b are pressure-bonded to each other by the pressure-bonding arm 4.
No. 0 was used and the pressure was applied by the pressure spring 37 having a spring pressure of 3 kg. On the other hand, when the gloss type toner is used, the spring pressure of the compression spring is set to 10 kg or more in order to increase the nip width. However, even in such a case, the A part nip width becomes non-uniform due to variations in spring pressure and the like, and the glossiness on the image becomes non-uniform. With regard to gloss type toner, the fixing temperature and the fixing speed of plain paper and thick paper are divided into a plain paper mode and a thick paper mode, respectively.

The purpose of this embodiment is to solve the above problems. FIG. 17 shows a method of performing the same without changing the fixing temperature and the fixing speed for thick paper and plain paper. Plain paper (less than 100 g / m ² ) by the piezoelectric sensor 48 (paper thickness detection sensor) provided in the registration roll U47 shown in FIG.
Or thick paper (100 g / m ² or more) is detected, the fixing pressure is controlled to an appropriate value before the paper (plain paper or thick paper) reaches the fixing device from the resist section, and the nip width is appropriately controlled. Is.

As shown in FIG. 16, the crimping arms 40a to 40c provided on both sides are abutted against the crimping force switching cams 38a to 38c similarly provided on both sides. The crimping force switching cams 38a to 38c are fixed to the crimping release shaft 42. A worm gear 49 is attached to the end of the crimp release shaft 42, and a drive motor 50 for both forward and reverse directions is installed.
Thus, the pressure release shaft 42 is rotated via the idle gear 51.

In the apparatus of this embodiment, the operation panel 33 of FIG. 2 is provided with a variable pressure contact force mode, and the user operates the key operation section 33a on the operation panel 33,
It is preferable to change this pressure contact variable mode. Also,
As a modified example of this embodiment, image gloss information that specifies whether to print with matte toner or gloss toner is added to the image information from the host device connected to the printer main body, and this image gloss is added. It is also possible to perform the above control in this embodiment based on the information.

As described above, in this embodiment, when the thick paper is detected, the pressure bonding cam is rotated in the direction of the arrow to increase the fixing pressure, and the optimum nip width for fixing the thick paper can be obtained. In addition, the pressure force of plain paper is lower than that of thick paper,
The optimum nip width for fixing plain paper can be obtained. In addition, since there is no change in the fixing temperature or the fixing speed when using thick paper, the wait time and the conveyance speed can be kept constant. The same applies to plain paper. <Fourth Embodiment> The purpose of this embodiment is to control so-called overshoot by controlling a heater that heats the fixing roll and the press roll in the fixing unit from the inside.

In the conventional fixing unit, the amount of heat transferred to the unfixed image can be represented by the product of heating time and heating temperature. That is, when the same fixing unit is used, the fixing temperature must be set higher as the fixing speed increases. As another method, it is possible to increase the contact area (nip width) between the fixing roll and the press roll and extend the time during which the unfixed image is in contact with the fixing roll without increasing the fixing temperature setting. Generally, since the silicone rubber that constitutes the main body of the fixing roll has a property of decomposing and deteriorating at high temperatures, it is preferable to increase the fixing speed by increasing the nip width.

In order to increase the nip width in order to efficiently transfer the heat from the heater to the unfixed image, the rubber hardness of the rubber itself is made soft so that the rubber layer is easily crushed, or the rubber thickness is increased to make the apparent rubber thick. There are two methods of softening the hardness so that the rubber layer is easily crushed. In the former case,
Lowering the hardness of the rubber itself lowers the heat resistance of the rubber. Therefore, it is practical to use the latter method.

However, when the rubber thickness is increased and 40 sheets of A4 size white paper are continuously passed by using the fixing device, the following phenomenon becomes more remarkable. That is, when the surface temperature of the fixing roll becomes 170 ° C. or lower, the heater is turned on to raise the temperature of the fixing roll. The timing of detecting the surface temperature of the fixing roll controls ON / OFF of the heater at intervals of 0.5 seconds.

When printing is started when the set temperature reaches 170 ° C., the surface temperature of the fixing roll is lowered to 170 ° C.
In order to become the following, the temperature sensor detects the temperature and turns on the heater. However, since it takes time for the heat of the heater to reach the fixing roll surface after passing through the rubber layer after passing through the core metal, the heat of the roll surface is mainly taken off by the paper at the beginning of printing, and the surface of the fixing roll is the main cause. The temperature keeps falling. After that, the heat of the heater reaches the surface of the roll and the surface temperature of the fixing roll gradually rises to 1
It approaches 70 ° C. When printing is finished when the surface temperature of the fixing roll reaches 170 ℃, the temperature sensor turns off the heater.
A signal is output and the heater is turned off. However, heat has already accumulated inside the rubber layer of the fixing roll, and energy is released to the surface of the fixing roll even after printing is completed. The so-called overshoot phenomenon occurs in which the heat energy that should be absorbed by the paper should disappear and the surface temperature of the fixing roll continues to rise because printing has ended. This unnecessarily raises the surface temperature of the fixing roll, which accelerates thermal deterioration of the rubber, and eventually causes a problem of shortening the life of the fixing unit.

Further, since the fixing temperature is higher than that when printing is started at the time of overshoot, there is no problem with the matte type toner having a relatively wide non-offset temperature region, but with the gloss type toner having a narrow non-offset temperature region, It causes high temperature offset.

Since the color image forming apparatus of this embodiment is the same as that of the first embodiment, its explanation is omitted. As shown in FIG. 4, the fixing unit includes a fixing roll 15a and a press roll 15b arranged in a fixing unit casing, and the fixing roll 15a and the press roll 15b are heated by a heater placed therein. Further, the fixing roll 15a and the press roll 15b are pressed against each other by the compression spring 37.

The fixing roll 15a has an LTV silicone rubber (thickness 2
mm, rubber hardness JIS_A5 °), and the surface is PFA
(Perfluoroalkoxy copolymer) tube (thickness 30 μm) is used for coating.

At the end of the fixing roll 15a, as shown in FIG. 4, the rubber thickness of the non-sheet passing portion is 1 mm. Further, as shown in FIG. 4, the end portion of the fixing roll 15a has a rubber thickness of 2 mm.
A temperature sensor 52a composed of a thermocouple or a thermistor for detecting the surface temperature of the portion and a temperature sensor 52b for detecting the surface temperature of the portion having a rubber thickness of 1 mm are arranged and are in contact with the roll surface.

The temperature detection timing on the surface of the fixing roll 15a controls the ON / OFF of the heater at intervals of 0.5 seconds, and the roll surface temperature detected by the temperature sensor is 1
When the temperature becomes 70 ° C. or lower, the heater is turned on and the roll surface temperature is controlled so as not to become 170 ° C. or lower. However, the temperature information used for detection and control is that the surface temperature of the fixing roll 15a is lowered. The temperature sensor 52a is used in the state, and the temperature sensor 52b is used when the surface temperature of the fixing roll is rising.

FIG. 18 shows the relationship between the time when 40 sheets of A4 size white paper are continuously passed and the surface temperature of the fixing roll with the above constitution. In the figure, when printing is started, the surface temperature of the fixing roll is lowered to 170 ° C. or lower. At this time, the temperature sensor detects the temperature and turns on the heater. However, since it takes time for the heat from the heater to reach the core of the fixing roll after passing through the rubber layer,
At the beginning of printing, the heat of the roll surface is mainly removed by the paper, and the temperature of the fixing roll surface continues to drop. At this time, since the temperature sensor 52a detects the surface temperature of the fixing roll due to printing earlier than the temperature sensor 52b, ON / OFF control of the heater is performed at the temperature detected by the temperature sensor 52a.

After that, the heat of the heater reaches the roll surface, and the fixing roll surface temperature gradually rises. When the surface temperature of the fixing roll 15a is rising, the heater ON / OFF is controlled by the temperature detected by the temperature sensor 52b. This is because the temperature sensor 52b detecting the thin rubber portion can detect the temperature rise due to the heater ON earlier than the temperature sensor 52a detecting the thicker rubber portion.

As described above, in the present embodiment, even when the printing operation is finished at the timing such that the temperature setting is 170 ° C. at the end of printing in the conventional example, the heater is turned off by the temperature sensor 52b before the conventional example. Since heat is not accumulated in the rubber, overshoot can be suppressed low as shown in FIG.

[0059]

As described above, according to the present invention, a plurality of pressure-bonding springs are installed in the fixing unit, and the fixing roll pressure can be changed by operating the cam and the arm depending on the position of the pressure-release lever. did. Therefore, the fixing unit for fixing the gloss toner and the matte toner can be shared. Moreover, the user can switch the image glossiness by a simple lever operation. Further, even if an image failure due to the offset occurs, the user can handle it by operating the lever. Further, by selecting the pressure force and the roll temperature suitable for the image and toner, the life of the fixing roll can be extended. Further, by installing a plurality of springs, the assembly is facilitated and the force of the springs is distributed to each roll support arm, so that the parts of the arm and frame are less likely to be deformed.

Further, in the present invention, the oil application roll bearing pedestal is installed on the fixing roll support arm, and the oil application roll pressure contact force is made variable by operating in conjunction with the fixing roll pressure release lever. As a result, the amount of oil suitable for the gloss type toner and the matte type toner can be supplied, so that the oil roll unit can be shared. Also, since the oil application roll also separates from the fixing roll when the pressure is released,
Can be bundled with the fixing unit during transportation.

In the present invention, when thick paper is detected,
By rotating the pressure cam in the direction of the arrow to increase the fixing pressure, it is possible to obtain the optimum nip width for fixing thick paper. Further, when the plain paper is used, the pressure-bonding force is reduced as compared with the thick paper, and the optimum nip width for fixing the plain paper can be obtained. In addition, since there is no change in the fixing temperature or the fixing speed when using thick paper, the wait time and the conveyance speed can be kept constant. The same applies to plain paper.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an overall configuration of a printer device according to a first embodiment.

FIG. 2 is an external perspective view of the printer device according to the first embodiment.

FIG. 3 is a circuit block diagram of the printer device according to the first embodiment.

FIG. 4 is a vertical sectional view of the fixing unit according to the first embodiment.

5 is a side cross-sectional view of the three crimp cams of FIG.

6A, 6B, and 6C are diagrams showing an operation example of the fixing unit of the first embodiment.

7A and 7B are diagrams illustrating an operation example of the fixing unit according to the first embodiment.

8A and 8B are diagrams illustrating an operation example of the fixing unit according to the first embodiment.

9A and 9B are diagrams showing an operation example of the fixing unit of the first embodiment.

FIG. 10 is a diagram illustrating an operation example of the fixing unit according to the second exemplary embodiment.

11A and 11B are diagrams illustrating an operation example of the fixing unit according to the second embodiment.

FIG. 12 is a diagram illustrating an operation example of the fixing unit according to the second exemplary embodiment.

FIG. 13 is a diagram illustrating an operation example of the fixing unit according to the second exemplary embodiment.

FIG. 14 is an external perspective view of the printer device according to the second embodiment.

FIG. 15 is an external perspective view of the printer device according to the second embodiment.

FIG. 16 is a diagram showing a driving device according to a third embodiment.

FIG. 17 is a diagram showing a driving device according to a third embodiment.

FIG. 18 is a graph showing the relationship between the time when 40 sheets of A4 paper are passed and the surface temperature of the heat roll in the fourth embodiment.

FIG. 19 is a diagram showing a conventional fixing unit.

[Explanation of symbols]

1 Printer device 2 Image forming section 3 Transport unit for double-sided printing 4 Paper feeder 5-8 Image forming unit 9 Photosensitive drum 10a Charger 10b print head 10c developing roll 10d transfer device 10e cleaner 11 paper cassettes 12 Standby roll 13 Conveyor belt 14 drive roll 15 Fixing unit 15a heat roll 15b press roll 15c Oil coating roll 16 MPF tray 16a Paper feed roller 17 Switching flap 18a to 18e Reverse transport roller pair 19 Conveyor roll 20 Paper ejection roll 21 Paper output section 22 Upper part of device 23 Device bottom 24 Front cover 26 I / F controller 27 frame memory 28 Printer controller 29 Printer printing section 30 CPU 31 ROM 32 EEPROM 33 Operation panel 33a Key operation part 33b display section 37a-37c Crimping spring 38a-38c Crimping force switching cam 39 Crimping release lever 40a, 40b roll support arm 40c Roll fixed support arm 41a-41c bearings 42 Crimp release shaft 43 Oil coated roll bearing 44 Oil coated roll bearing base 47 Registration Roll U 48 Piezoelectric sensor 49 Worm gear 50 drive motor 51 idle gear 52a, 52b Temperature sensor

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mitsugu Oishi             2-229 Sakuragaoka, Higashiyamato-shi, Tokyo             Casio Computer Co., Ltd. Tokyo office (72) Inventor Akinori Furusawa             2-229 Sakuragaoka, Higashiyamato-shi, Tokyo             Casio Computer Co., Ltd. Tokyo office F term (reference) 2H030 AA00 AB02 AD04 BB02 BB23                 2H033 AA09 AA10 BA43 BA46 BB06                       BB14 BB15 BB18 BB30 BB34                       BB35 CA02 CA16 CA30 CA39                       CA45                 3J103 AA02 BA43 CA63 FA18 GA27                       GA57 GA58 GA60 GA66 GA73

Claims (10)

[Claims] 1. A multi-color toner image is transferred onto a transfer material, and the transfer material is nipped and conveyed by a heating and fixing means having a heating roller and a pressure roller which have a heat source on at least one side and are in pressure contact with each other. In the color image forming apparatus, the heat fixing unit includes a supporting unit that movably supports one of the heating roller and the pressure roller to the other and press-contacts / separates the supporting unit in the press-contacting direction. At least an urging unit for urging the heating roller and the pressure roller so that the image passed through the space between the heating roller and the pressure roller and fixed by heat has different glossinesses. A color image forming apparatus comprising a formed image gloss switching unit for changing the pressure contact force of the image forming apparatus. 2. The heating and fixing means further comprises an oil application roller and an oil supply amount control means, and the oil supply amount control means works in conjunction with the formed image gloss switching means to supply oil to the oil application roller. The color image forming apparatus according to claim 1, wherein the amount is controlled. 3. The formed image gloss switching means is a switching lever that engages with the heating and fixing means to change the pressure contact force between the heating roller and the pressure roller, or 2. The color image forming apparatus described in 2. 4. The formed image gloss switching means includes a driving means for engaging the heating and fixing means to change the pressure contact force between the heating roller and the pressure roller, and a drive control means for controlling the driving means. Claim 1 characterized in that it is composed of
Or the color image forming apparatus described in 2. 5. An image obtained by transferring a toner image of a plurality of colors onto a transfer material, the transfer material being nipped and conveyed by a heating and fixing means having a heating roller and a pressure roller which have a heat source on at least one side and are in pressure contact with each other. In the color image forming apparatus, the heat fixing unit includes a supporting unit that movably supports one of the heating roller and the pressure roller to the other and press-contacts / separates the supporting unit in the press-contacting direction. A plurality of biasing means for biasing, and a pressure contact force varying means for varying the pressure contact force between the heating roller and the pressure roller by selectively restricting the action of the plurality of biasing means on the supporting means. And a color image forming apparatus. 6. The heat fixing unit further comprises an oil applying roller and an oil supply amount control unit, and the oil supply amount control unit operates in conjunction with the pressure contact force varying unit to supply the oil supply amount of the oil applying roller. 6. The color image forming apparatus according to claim 6, wherein the color image forming apparatus is controlled. 7. The pressure contact force varying means is a switching lever that engages with the heat fixing means and varies the pressure contact force between the heating roller and the pressure roller.
Or the color image forming apparatus described in 6. 8. The pressure contact force varying means comprises drive means for engaging the heat fixing means and varying the pressure contact force between the heating roller and the pressure roller, and drive control means for controlling the drive means. 9. The color image forming apparatus according to claim 5, which is configured. 9. A detection means for detecting the type of the transfer material is further provided, and the drive control means makes the pressure contact force between the heating roller and the pressure roller variable based on the detection result of the detection means. 9. The color image forming apparatus according to claim 4, wherein the color image forming apparatus is a color image forming apparatus. 10. The drive control means is configured to control the heating roller and the pressure roller based on image gloss information in image information received by the color image forming apparatus from a host device connected to the color image forming apparatus. 9. The color image forming apparatus according to claim 4, wherein the pressure contact force of is variable.