JP3195748B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an image forming apparatus such as a copying machine and various printers, and more particularly, to a method for recording paper through an endless fixing belt stretched between a heating roller and a fixing roller. A paper entry guide provided below and adjacent to the fixing belt that conveys the recording paper to a nip formed by the fixing roller and the pressure roller so as to be fixed by being sandwiched between the fixing roller and the pressure roller. And a fixing device having the same.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic fixing device, a pair of upper and lower rollers coated with a non-adhesive substance such as fluororesin or silicone rubber is used, and a heat source such as a halogen lamp is provided therein. A heat roller system is widely used in which a suitable pressure is applied in between, and a recording paper having toner transferred thereto is inserted into the nip portion to fix the recording paper.

In the heat roller method, the toner and the recording paper must be rapidly raised to a temperature at which the toner and the recording paper can be fixed only by a nip formed by two upper and lower rollers which are pressed.
In order to satisfy the fixing configuration at a certain transport speed, it is necessary to increase the outer diameter of the heat roller to secure the heat capacity, and it is necessary to considerably increase the fixing temperature, and to prevent high temperature offset due to this, A large amount of oil for release was indispensable. However, in this method, it is difficult to shorten the warm-up time and to save power, and there are problems such as image contamination due to oil for releasing.

However, a belt-type fixing device has recently been proposed as a technique capable of solving the above problem.
No. 318001 is proposed.

FIG. 16 shows this belt type fixing device.
This will be described below.

In this fixing device, an endless fixing belt 44 is stretched between a heating roller 42 provided with a heating source 41 and a fixing roller 43, and the fixing roller 43 is fixed from below through the fixing belt 44. A pressure roller 45 for pressing is provided, and a substantially linear shape is provided at a position close to and below the fixing belt 44 on the upstream side of the nip portion formed by the fixing belt 44 (the fixing roller 43) and the pressure roller 45 in the recording paper conveyance direction. The paper input guide 46 is provided. The fixing belt 4
Reference numeral 4 denotes a low heat capacity belt in which a thin endless metal belt is coated with a non-adhesive silicone rubber or the like.

When the recording paper of the unfixed image is conveyed to the fixing device having the above structure, the toner and the recording paper are preheated via the fixing belt 44, and the melting of the toner is started. As a result, the temperature setting of the nip formed by the fixing belt and the pressure roller can be set low, and the heat capacity of the fixing belt 44 is small, so that when the recording paper passes through the nip, the fixing belt 44 is rapidly cooled, It was possible to suppress the temperature of the toner on the recording paper that was released from the fixing belt 44 at the exit of the nip portion, and it was possible to obtain a good image without offset with no oil or a small amount of oil applied.

[0008]

However, the above-mentioned fixing device has not been sufficiently studied in consideration of the installation environment of the main body and the duplex printing mode. That is, since the paper input guide is disposed at a position below the fixing belt and close to the fixing belt, when operating in a high-temperature and high-humidity environment or performing backside printing in the duplex printing mode, the leading edge of the recording paper is wavy. Or
As a result, the leading edge of the recording paper after transfer may not be inserted into the narrow space between the paper input guide and the fixing belt, resulting in the occurrence of JAM on the recording paper or the recording paper during the printing operation. When a jam occurs and the main body stops operating with the JAM paper inserted between the paper input guide and the fixing belt, the user needs to remove the JAM paper inside the main body. It was difficult to remove the JAM paper in the narrow space between the guide and the fixing belt, which caused the JAM recovery to deteriorate.

In order to solve the above-mentioned problem, the distance between the paper feed guide and the fixing belt may be set wide in advance. In this case, the preheating effect from the fixing belt to the paper feed guide (paper feed guide) ), The temperature of the unfixed toner on the recording paper is raised to improve the fixability.). Another problem is that when the recording paper is a paper with a large heat capacity such as thick paper, it is difficult to obtain a good fixing temperature only by the preheating effect from the paper input guide. We needed to make it longer.

The fixing device of the present invention has been made in view of the above-mentioned problem, and when the recording paper is inserted between the fixing belt and the paper input guide, the paper input guide is moved to fix the recording paper to the fixing belt. It is an object of the present invention to ensure that paper can be inserted between the paper input guides.

[0011]

According to another aspect of the present invention, there is provided a fixing device, comprising: a heating roller for heating a recording sheet onto which a toner image is transferred; and a recording sheet heated by the heating roller. A fixing roller for fixing the toner image to the
An endless fixing belt stretched over the heating roller and the fixing roller; a pressing roller for nipping and pressing a recording sheet with the fixing roller via the fixing belt; A paper input guide provided adjacent to and below the fixing belt on the upstream side in the conveyance direction of the recording paper in the nip portion formed by the roller and the paper input guide. If there is no recording paper above,
To perform heating from the heat roller to the paper input guide,
The paper guide is close to the fixing belt is provided with a Nyukami guide moving means for moving the upper fill paper guide to a position separated from the fixing belt at the time of entering the paper of the recording paper. With the above configuration, when there is no recording paper on the paper input guide, the fixing belt
The paper guide is brought close to the
Heating is performed from the rollers to the paper input guide, so the recording paper
When paper enters between the paper input guide and the fixing belt,
Due to the heat of the paper input guide caused by heat,
It is possible to improve the fixing performance by raising the temperature of the fixing toner.
Wear. Furthermore, even if the recording paper has wavy or curled paper at the leading edge, the paper input guide separates from the fixing belt when the recording paper is input. Paper is inserted.

According to a second aspect of the present invention, there is provided a fixing device provided with a recording paper detecting sensor for detecting a recording paper in a conveyance path located upstream of the paper input guide. There is provided a paper entry guide moving means for separating the entry paper guide from the fixing belt and returning the paper entry guide to an initial position close to the fixing belt after a lapse of a predetermined time from the detection of the recording paper. With the above configuration, when the recording paper is not on the paper input guide, the paper input guide is brought close to the fixing belt, the interval between the two is narrowed, and the preheating from the fixing belt to the paper input guide is performed. When the paper approaches the upstream part, the interval between the fixing belt and the paper input guide is increased to facilitate the input of the recording paper, and when the leading edge of the recording paper is inserted between the fixing belt and the paper input guide, The heat from the fixing belt can be reliably applied to the recording paper and the unfixed toner on the recording paper until the interval between the fixing belt and the paper input guide is reduced again and the recording paper is inserted into the nip portion.

According to a third aspect of the present invention, there is provided a fixing device for heating a recording sheet on which a toner image is transferred, a fixing roller for fixing a toner image on the recording sheet heated by the heating roller, and a heating roller. An endless fixing belt stretched over the fixing roller, a pressure roller for sandwiching and pressing the recording paper with the fixing roller via the fixing belt, and a fixing roller and the pressure roller. A paper feed guide provided in the vicinity of the fixing belt on the upstream side of the nip portion in the conveyance direction of the recording paper, and the paper guide is movably provided, and the heating is performed when the fixing belt is stopped. B
In order to heat the paper input guide from the roller, the paper input guide is brought into contact with the fixing belt, and the paper input guide is moved to a position separated from the fixing belt when the recording paper is input. Paper guide moving means is provided. With the above configuration, when the fixing belt is stopped , the heating roller is
In order to heat the paper input guide , the paper input guide is in contact with the fixing belt, so the contact between the fixing belt and the paper input guide preheats the larger paper input guide,
Even fixing of recording paper having a large heat capacity such as thick paper can be reliably performed.

According to a fourth aspect of the present invention, there is provided a fixing device comprising:
When M occurs, the paper input guide is separated from the fixing belt. With the above configuration, the recording paper can be easily removed when a JAM occurs.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a printer using a fixing device of the present invention will be described with reference to FIG.

The printer according to the present invention includes a paper feed tray 2 on a side surface of a main body 1 for inserting a plurality of sheet-like recording papers. A paper feed roller 3 for sequentially feeding the recording paper is provided, and a PS sensor 14 for detecting the leading end of the recording paper is disposed downstream of the paper feed roller 3 in the transport direction of the recording paper. A transport path a4 is provided substantially horizontally, and a drum cartridge 6 having a photosensitive drum 5 and a transfer roller 7 are disposed downstream of the recording paper transport path a4.

A fixing device 20 is provided further downstream of the transfer roller 7 to fix the toner image formed on the recording paper and to form an image on a discharge tray 11 provided on a front cover of the main body 1. And a U-turn guide 12 for discharging the recording paper. An optical unit 15 for irradiating the photosensitive drum 5 with light is provided on the right side of the drum cartridge 6.

The light 17 emitted from the optical unit 15 is irradiated on the surface of the photosensitive drum 5 charged in advance to expose the photosensitive drum 5, so that an electrostatic latent image is formed on the surface of the photosensitive drum 5. It is formed.

This electrostatic latent image is adhered to the photosensitive drum 5 by toner supplied from the developing device 8 and developed,
This toner image is sent toward the contact portion between the photosensitive drum 5 and the transfer roller 7 as the photosensitive drum 5 rotates.

On the other hand, at this time, recording paper is supplied from the paper supply tray 2 by the paper supply roller 3, and this recording paper is transported along the recording paper transport path a4, and the PS sensor 14
N, stopped PS roller 1 composed of a pair of upper and lower
Sent to 3 copies. Thereafter, the PS roller 13 rotates in accordance with the light emission timing of the optical unit 15 controlled by the control unit 19 based on the ON signal of the PS sensor 14, and the recording paper contacts the photosensitive drum 5 and the transfer roller 7. It is conveyed to a transfer area which is a contact part. When the recording paper passes through this area, the toner image formed on the surface of the photosensitive drum 5 is transferred to the recording paper by a potential difference between the electric charge and the electric charge on the surface of the recording paper.

Next, the recording paper is guided to a recording paper transport path b9 holding a suction sensor 10 for detecting the recording paper.
Thereafter, the sheet is fed into the fixing device 20.

The fixing device 20 has an endless fixing belt 21 stretched between a heating roller 23 having a heating source 26 provided therein and a fixing roller 24, and the fixing roller 21 is fixed from below through the fixing belt 21. Pressurizing roller 2 that pressurizes 24
And a substantially linear paper input guide 2 at a position close to and below the fixing belt 21 upstream of the nip formed by the fixing belt 21 and the pressure roller 25 in the recording paper conveyance direction.
2 is provided. The fixing belt 21 is a low heat capacity belt in which a thin endless metal belt is coated with a non-adhesive silicone rubber or the like.

When the recording paper on which the unfixed toner image is formed is conveyed to the fixing device 20 having the above structure, the toner and the recording paper are preheated via the fixing belt 21 and the melting of the toner image starts. Is done. As a result, the temperature of the nip 27 formed by the fixing belt 21 and the pressure roller 25 can be set low, and the heat capacity of the fixing belt 21 is small. It is possible to suppress the temperature of the toner on the recording paper, which is cooled and is released from the fixing belt 21 at the exit of the nip 27, and it is possible to obtain a good image without any offset with no oil or a small amount of oil applied.

The recording paper sent from the fixing device 20 is guided above the main body 1 along the U-turn guide 12 and is discharged onto the paper discharge tray 11.

FIG. 2 is a sectional view showing the structure of the fixing device 20 of the present invention, and FIG. 3 is a control block diagram for controlling the rotation operation of the paper input guide.

The paper input guide 22 of the fixing device 20 has a fulcrum P _0.
It is pivotally supported by the fulcrum P ₀ so as to be rotational movement about the. A solenoid 29 is provided upstream of the paper input guide 22.
The return springs 30 are respectively disposed above the return springs 30. When the solenoid 29 is normally in the OFF state, the upper end edge of the plunger 29a abuts the stopper 29b due to the upward return force of the return spring 30, and the paper input guide 22
Stationary maintaining the spacing of the fixing belt 21 and X ₀ is. The solenoid 29 is ON excel its attraction force spring force of the return spring 30, the plunger lowered 29a to the lowermost end, as a result, Nyukami guide 22 is rotated and moved in the clockwise direction about the fulcrum P _0, fixing to still maintaining the spacing of the belt 21 and X _1.

As described above, the paper input guide 22 can be rotated by the ON / OFF control of the solenoid 29.

Next, the timing of the rotational movement of the paper input guide 22 during printing will be described below.

In the transfer step, the recording paper 31 having the toner adhered to the upper surface is conveyed onto the recording paper conveying path b9, and the leading end thereof turns on the suction sensor 10 for detecting the recording paper. The ON signal of the suction sensor 10 is sent to the control unit 19, and after that, an ON signal is sent to the solenoid 29 after t ₀ seconds, and the ON operation of the solenoid 29 causes the paper input guide 22 to rotate clockwise about the fulcrum P _0. moving, stationary keeping the distance between the fixing belt 21 and X _1, the leading edge of the recording sheet 31 is Nyukami the widened opening portion of the fixing belt 21 and the Nyukami guide 22 (FIG. 4).

Next, an OFF signal is sent from the control unit 19 to the solenoid 29 after t ₁ second, and the OFF state of the solenoid 29 is set.
Nyukami guide 22 is pulled upward by the return force of the upward operation and the return spring 30, the interval between the fixing belt 21 is returned to X ₀ (Figure 5). Thereafter, the recording paper 31 receives a preheating action from the fixing belt 21 and the paper input guide 22, and is conveyed to the nip portion 27 to complete the fixing of the unfixed toner image to the recording paper 31.

Next, the operation of the paper input guide 22 when the recording paper JAM occurs during printing will be described below.

In the printer, in addition to the suction sensor 10, a plurality of recording paper detecting sensors (not shown) are arranged in the transport path of the recording paper 31. When a recording paper JAM is generated at any point in the transport path, a signal of the recording paper JAM is sent to the control unit 19 by a sensor at the position or in the vicinity thereof. The printer body 1 interrupts the printing operation and sends an ON signal to the solenoid 29 from the control unit 19 in synchronization with the timing, so that the solenoid 29 is turned on. As a result, the paper input guide 22 moves to the fulcrum P _0.
Rotates and moves in a clockwise direction about the spacing between the fixing belt 21 is spread X ₁ (FIG. 6).

FIG. 7 shows ON-OF of the suction sensor 10.
A time chart of the F signal, the ON / OFF signal of the solenoid 29, and the interval between the fixing belt 21 and the paper input guide 22 shows that the following equation (1) is provided between t ₀ , t ₁ , L ₀ , and V. ,
Control is performed so that the relationship of Expression (2) is established.

T ₀ <L ₀ / V (1) t ₁ > L ₀ / V (2) t ₀ : The leading end of the recording paper 31 turns on the suction sensor 10.
T ₁ : The time from when the solenoid 29 is turned on t ₁ : The leading end of the recording paper 31 turns on the suction sensor 10
From to, time L ₀ to the solenoid 29 is OFF: distance from the suction sensor 10 to Nyukami guide 22 upstream edge V: As in the above transport speed of the recording sheet 31, constitutes a fixing device 20, the control In this case, the leading edge of the recording paper is caught in the opening between the fixing belt 21 and the paper input guide 22 even when the leading edge is wavy, such as when printing on the back side in the duplex printing mode or when the recording paper is curled. The recording paper JAM does not occur, and the recording paper JAM occurs during printing.
Even when the AM paper is removed, since the distance between the fixing belt 21 and the paper input guide 22 is wide, the fixing device 20 is removed.
A part of the JAM paper can be easily removed.

Next, a fixing device according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 8 is a cross-sectional view showing the configuration of the fixing device according to the second embodiment of the present invention, and FIG. 9 is a control block diagram for controlling the rotation operation of the paper input guide.

The second embodiment operates similarly to the first embodiment in that the paper input guide 22 of the first embodiment performs a rotating operation. However, the stationary state of the paper input guide 22 is increased by one in comparison with the first embodiment. I have. That is, in the first embodiment, the paper input guide 22 is stationary while keeping an interval between the fixing belt 21 and either X ₀ or X _1, but in the second embodiment, there is a state in which the paper input guide 22 further contacts the fixing belt 21. .

The rotation of the paper input guide 22 in the second embodiment is performed by a cam 32, a cam spring 33, and a cam drive motor (not shown) for rotating the cam 32. Nyukami guide 22 is always pulled downward by the cam spring 33, the cam 3 which rotates about the P ₁
With the rotation angle of 2, the rotation is made about P ₀ and its position is determined. The rotation of the fixing belt 21 is controlled by a fixing belt driving motor (not shown).

The operation when the printing operation is performed from the standby state of the printer body will be described below.

Hereinafter, the rotation angle of the cam 32 shown in FIG. 10 is α, the rotation angle of the cam 32 shown in FIGS.
The rotation angle of the cam 32 shown in FIG. That is,
The cam 32 is controlled to stop at any of the positions α, β, and γ.

When the printer main body is in a standby state, the fixing belt 2
1 is stopped, and a stop signal is sent to the control unit 19 from a fixing belt drive motor (not shown). Upon receiving the stop signal, the control unit 19 and a cam drive motor (not shown) rotate the cam 32 to the position of α, so that the paper input guide 22 moves the upper surface of the upstream side to the surface of the fixing belt 21. It is stopped at the contact position (FIG. 10).

Next, when a print command is input to the printer from an external device such as a personal computer, first, the controller 19
The cam 32 is rotated clockwise by a cam drive motor (not shown) until the rotation angle becomes β.
2 stops maintaining the spacing of the fixing belt 21 and X ₀ (Fig. 1
1).

When the recording paper 31 having the toner adhered to the upper surface in the transfer step is conveyed to the recording paper conveyance path b9, and the leading end of the recording paper 31 turns on the suction sensor 10 for detecting the recording paper, the ON signal of the suction sensor 10 is turned on. Is transmitted to the control unit 19, and after t ₀ seconds, the cam 32 is rotated clockwise by the control unit 19 and a cam drive motor (not shown) until the rotation angle becomes γ, and the paper input guide 22 is fixed to the fixing belt 2.
Keeping the distance between the 1 and X ₁ is stopped, the leading edge of the recording sheet 31 is Nyukami the widened opening portion of the fixing belt 21 and Nyukami guide (Fig. 12).

Thereafter, after elapse of t ₁ second, the cam 32 is rotated counterclockwise by the control unit 19 and a cam drive motor (not shown) until the rotation angle becomes β, and the paper input guide 22 is again moved to the fixing belt 21. And X ₀ and stops (FIG. 13). Thereafter, the recording paper 31 receives a preheating action from the fixing belt 21 and the paper input guide 22, and is conveyed to the nip portion 27 to complete the fixing of the unfixed toner image to the recording paper 31.

Next, the operation of the paper input guide 22 when the recording paper JAM occurs during printing will be described.

The operation when a JAM occurs is the same as in the first embodiment. The printer body interrupts the printing operation, and controls the cam drive motor (not shown) from the 32 is rotated until the rotation angle becomes gamma, distance between Nyukami guide 22 and the fixing belt 21 extends in X ₁ (FIG. 14). In this case, the fixing belt 2
1 is stopped and the standby state is the same as that of the fixing belt 21 being stopped.
Since the signal of AM is sent to the control unit 19, it is possible to distinguish from the standby state.

The above statement of t _0, t ₁ and figure L ₀ is the same as in the first embodiment, and, with t _0, t ₁ and L ₀ recording sheet 31
Equation (1), Equation (2)
Holds.

FIG. 15 shows ON-O of the suction sensor 10.
FF signal, rotation angle of cam 32, operation of fixing belt 21,
4 shows a time chart of the interval between the fixing belt 21 and the paper input guide 22.

If the fixing device is configured and controlled as described above, the recording paper can be printed even when the recording paper has a wavy or curled tip as in the case of environmental fluctuations or backside printing in the duplex printing mode. The leading end of the paper feed guide 31 does not get caught in the opening between the fixing belt 21 and the paper input guide 22 to prevent the occurrence of JAM on the recording paper. Even when printing is performed on recording paper having a large heat capacity such as thick paper, that is, when a large preheating effect is required by the paper input guide 22, the fixing belt 21 contacts the paper input guide 22. Larger preheating can be performed by heat transfer, and then a preheating effect from the paper input guide 22 to the back side of the recording paper in a printing state can be expected. Even when printing on a recording paper having a large heat capacity such as thick paper,
Good fixing strength is obtained. During printing, the recording paper JA
Even when M occurs and JAM paper is removed from the printer, the JAM paper can be easily removed from the fixing device 20 because the interval between the fixing belt 21 and the paper input guide 22 is wide.

In the above embodiment, when the recording paper JAM occurs, the paper input guide 22 is moved in the same manner as when the recording paper is input, but the movement amount at this time is further increased to remove the JAM paper. You may make it easier.

[0050]

According to the first aspect of the present invention, there is provided a fixing device for heating a recording sheet on which a toner image has been transferred, a fixing roller for fixing a toner image on the recording sheet heated by the heating roller, and a heating roller. An endless fixing belt stretched between the roller and the fixing roller, a pressing roller that presses the recording paper with the fixing roller via the fixing belt,
A paper input guide provided in the nip portion formed by the fixing roller and the pressure roller at a position upstream of the fixing belt in the conveying direction of the recording paper and close to and below the fixing belt, the paper input guide being movable. When there is no recording paper on the paper input guide
Is used to heat the paper input guide from the heating roller.
In order, the said input paper guide is close to the fixing belt, since there is provided a Nyukami guide moving means for moving the upper fill paper guide to a position separated from the fixing belt at the time of entering the paper of the recording sheet, the upper fill paper If there is no recording paper on the guide,
Close the paper guide and the gap between the two
The paper is heated from the roller to the paper input guide,
When paper is inserted between the paper input guide and the fixing belt,
Undetermined on the recording paper due to the heat of the paper input guide
The fixing temperature can be improved by raising the temperature of the toner
You. In addition, even when the recording paper has a wavy or curled tip, the paper input guide is separated from the fixing belt when entering the recording paper, so that the space between the paper input guide and the fixing belt becomes large, making recording easier. Even when the paper is inserted and the leading edge of the recording paper has waving or curling, the recording paper can be reliably inserted without generating JAM.

According to a second aspect of the present invention, there is provided a fixing device provided with a recording paper detecting sensor for detecting a recording paper in a conveying path located on the upstream side of the paper input guide. Since the paper guide is moved away from the fixing belt and a paper guide moving means is provided to return the paper guide to an initial position close to the fixing belt after a lapse of a predetermined time from the detection of the recording paper, the paper is fed. When the recording paper is not on the guide, the paper guide is brought close to the fixing belt, the interval between them is narrowed, and the preheating from the fixing belt to the paper guide is performed.When the recording paper approaches the upstream part of the paper guide, the fixing belt When the leading edge of the recording paper is inserted between the fixing belt and the paper input guide, the gap between the fixing belt and the paper input guide is again increased. Make the recording paper narrower Until the recording paper and the unfixed toner on the recording paper are inserted into the paper sheet, the heat from the fixing belt can be reliably applied to the recording paper. Can be fixed.

According to a third aspect of the present invention, there is provided a fixing device, comprising: a heating roller for heating a recording sheet onto which a toner image has been transferred; a fixing roller for fixing the toner image on the recording sheet heated by the heating roller; An endless fixing belt stretched over the fixing roller, a pressure roller for sandwiching and pressing the recording paper with the fixing roller via the fixing belt, and a fixing roller and the pressure roller. A paper feed guide provided in the vicinity of the fixing belt on the upstream side of the nip portion in the conveyance direction of the recording paper, and the paper guide is movably provided, and the heating is performed when the fixing belt is stopped. B
In order to heat the paper input guide from the roller, the paper input guide is brought into contact with the fixing belt, and the paper input guide is moved to a position separated from the fixing belt when the recording paper is input. Since the paper guide moving means is provided, when the fixing belt is stopped , the heating roller moves from the heating roller to the paper input guide.
In order to heat the recording paper , the paper input guide comes into contact with the fixing belt , so that the paper input guide comes into contact with the fixing belt and the paper input guide, thereby preheating the paper input guide. Can be surely performed even when the image is fixed.

According to a fourth aspect of the present invention, there is provided a fixing device comprising:
Since the paper input guide is separated from the fixing belt when M occurs, the recording paper can be easily removed when JAM occurs.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a printer using a fixing device of the present invention.

FIG. 2 is a sectional view showing Embodiment 1 of the fixing device of the present invention.

FIG. 3 is a control block diagram for controlling the operation of a paper input guide of the fixing device of FIG. 2;

FIG. 4 is a cross-sectional view illustrating a state when paper enters the fixing device according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a state after the sheet enters the fixing device according to the first embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a state when JAM occurs in the fixing device according to the first embodiment of the present invention.

FIG. 7 is a time chart illustrating operation timing of each unit according to the first embodiment of the present invention.

FIG. 8 is a sectional view illustrating a fixing device according to a second embodiment of the present invention.

FIG. 9 is a control block diagram for controlling the operation of a paper input guide of the fixing device of FIG. 8;

FIG. 10 is a cross-sectional view illustrating a state of the fixing device according to the first embodiment of the present invention in a standby state.

FIG. 11 is a cross-sectional view illustrating a state before the sheet enters the fixing device according to the first embodiment of the present invention.

FIG. 12 is a cross-sectional view illustrating a state when paper enters the fixing device according to the first embodiment of the present invention.

FIG. 13 is a cross-sectional view illustrating a state after the sheet enters the fixing device according to the first embodiment of the present invention.

FIG. 14 shows a JAM in the fixing device according to the first embodiment of the present invention.
It is sectional drawing which shows the state at the time of an occurrence.

FIG. 15 is a time chart showing operation timing of each unit according to the first embodiment of the present invention.

FIG. 16 is a cross-sectional view illustrating a conventional fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer main body 21 Fixing belt 22 Paper input guide 23 Heating rotor 24 Fixing roller 25 Pressure roller 26 Heating source 27 Nip part 29 Solenoid 30 Return spring

Continuation of the front page (56) References JP-A-6-318001 (JP, A) JP-A-8-137309 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 13 / 20 G03G 15/20

Claims (4)

(57) [Claims] 1. A heating roller for heating a recording sheet onto which a toner image has been transferred, a fixing roller for fixing a toner image on the recording sheet heated by the heating roller, and a tension roller attached to the heating roller and the fixing roller. Endless fixing belt, a pressure roller for pressing the recording paper between the fixing roller via the fixing belt and pressing the recording paper, a recording paper in a nip formed by the fixing roller and the pressure roller And a paper feed guide provided in the vicinity of the fixing belt on the upstream side in the conveyance direction of the paper feeder, wherein the paper feed guide is movably provided, and there is no recording paper on the paper feed guide. Is the above heating roller
From the paper input guide to heat the paper input guide from
A paper input guide moving means for moving the paper input guide to a position separated from the fixing belt when the recording paper is input. 2. A recording paper detecting sensor for detecting a recording paper in a transport path located on the upstream side of the paper input guide, and when the recording paper is detected by the recording paper detecting sensor, the paper input guide is moved to the fixing belt. 2. The fixing device according to claim 1, further comprising: a paper input guide moving unit that separates the paper input guide from the recording paper and returns the paper input guide to an initial position close to the fixing belt after a lapse of a predetermined time from the detection of the recording paper. 3. A heating roller for heating a recording sheet onto which a toner image has been transferred, a fixing roller for fixing a toner image on the recording sheet heated by the heating roller, and a tension roller attached to the heating roller and the fixing roller. Endless fixing belt, a pressure roller for pressing the recording paper between the fixing roller via the fixing belt and pressing the recording paper, a recording paper in a nip formed by the fixing roller and the pressure roller in the fixing device having a Nyukami guide in the conveying direction upstream side is provided near the lower side of the fixing belt, provided over the complete paper guide movably, said from the heating roller when stopping of the fixing belt Insertion paper
In order to heat the guide, a paper input guide moving means is provided for bringing the paper input guide into contact with the fixing belt and moving the paper input guide to a position separated from the fixing belt when recording paper is input. A fixing device. 4. The fixing device according to claim 1, wherein the paper input guide is separated from the fixing belt when a paper jam occurs.