JP2002082554A - Fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably secure nip width in a fixing device having a sheet type pressing member. SOLUTION: In this fixing device, the sheet type pressing member 13 is made to abut on a fixing roller 12 so as to form a nip part, and recording paper to which a toner image is transferred is made to pass through the nip part, whereby the toner image is fixed on the recording paper. The device is provided with a coil spring 20 arranged between the member 13 and a main body and energizing the member 13 to the roller 12 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device and an image forming apparatus applied to an electrophotographic apparatus such as a facsimile machine, a printer, a copying machine or a multifunction machine having the functions thereof.

[0002]

2. Description of the Related Art FIG. 5 is a side view showing the internal structure of a conventional fixing device.
A fixing roller 52 is disposed inside the fixing roller 50 to heat the fixing roller 50.
3 is a temperature detecting means for detecting the temperature of the fixing roller 50;
Reference numeral 4 denotes a fixing roller 5 which fixes the recording paper adhered to the fixing roller 50.
A separation claw for separating the fixing roller 50 from the fixing roller 55, a cleaning pad 55 that contacts the fixing roller 50 to clean the fixing roller 50, a cleaning pad holder 56 that supports the cleaning pad 55, and a rotation of the fixing roller 50 with respect to the cleaning pad 55. Reference numeral 58 denotes an entrance guide plate attached to the recording paper entrance of the fixing device main body, and 59 denotes a paper discharge roller provided on the recording paper exit side of the fixing device.

The recording paper onto which the toner image has been transferred enters the nip portion between the fixing roller 50 and the pressure roller 51 via the entrance guide plate 58. Then, after the toner image is fixed on the recording paper by being pressed / heated in the nip portion,
The paper is discharged to the outside via the paper discharge roller 59. The toner adhered to the fixing roller 50 when the recording paper passes through the nip is removed by the cleaning pad 55.

[0004] The surface temperature of the fixing roller 50 is detected by a temperature detecting means 53, and based on the detection result of the temperature detecting means 53, heating control by a fixing heater 52 is performed by a control means (not shown).

Heretofore, in the fixing apparatus, an infrared heater or a halogen heater is adopted as a fixing heater, and a fixing roller and a pressure roller are most commonly used. However, since the pressure roller has a structure in which a silicon rubber layer is formed on a cored bar and a release layer such as a tube made of a fluororesin is formed thereon, the heat capacity increases, and even if heating is started, heat is applied. The pressure roller does not easily warm up, which is a cause of defective fixing. There was also a disadvantage that the parts cost was high. Further, a large pressing force is required in order to secure an appropriate nip width at the nip portion between the fixing roller and the pressure roller, and the pressure causes a stress on the recording paper to cause a fixing wrinkle.

Therefore, a fixing device for forming a nip by pressing a sheet-shaped member against the fixing roller instead of the pressing roller, and fixing the unfixed image to the recording paper by passing the recording paper through the nip portion. Are being studied. With such a configuration, the sheet-shaped member easily warms up, it is possible to secure a nip width, and it is possible to increase the thermal efficiency as compared with the conventional machine.

[0007]

By using a sheet-like member for the pressure roller, it is possible to secure a nip width. However, it is desired to secure a more stable nip width in order to increase the thermal efficiency more reliably.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device having a sheet-shaped pressing member and a fixing device and an image forming apparatus capable of stably securing a nip width.

[0009]

According to a first aspect of the present invention, there is provided a fixing roller having a heating source therein, and a sheet-like sheet contacting the fixing roller with a predetermined pressure applied thereto. A pressure member, and presses / heats the recording paper onto which the toner image has been transferred by the electrophotographic process when the recording paper passes between the fixing roller and the sheet-shaped pressing member. A fixing device for fixing an image, further comprising an urging member disposed between the sheet-shaped pressing member and the main body, and for urging the sheet-shaped pressing member toward the fixing roller. And With this configuration, the sheet-shaped pressing member can stably press the fixing roller, and the nip width can be stably secured. As a result, the thermal conductivity of the sheet-shaped pressing member is improved, so that the sheet-shaped pressing member can be quickly warmed.

The invention according to claim 2 is characterized in that the biasing member is a coil spring. With this configuration, it is easy to adjust the pressing force of the sheet-shaped pressing member.

The invention according to claim 3 is characterized in that the biasing member is a sponge member. With this configuration, the temperature change of the sheet-shaped pressing member can be reduced due to the heat storage property of the sponge member.

The invention according to a fourth aspect is characterized in that the urging force of the urging member is applied to a portion of the sheet-shaped pressing member other than a contact portion with the fixing roller. With such a configuration, the elasticity of the sheet-shaped pressing member in the vicinity of the nip can be maintained, and the recording paper can easily pass through the nip.

According to a fifth aspect of the present invention, the biasing member is a coil spring, one end of the coil spring is attached to the sheet-like pressing member, and the other end is attached to the main body. Is configured to be variable. With this configuration, since the amount of expansion and contraction of the coil spring can be adjusted, the pressure applied by the sheet-shaped pressing member to the fixing roller can be adjusted.

The invention according to claim 6 is characterized in that a plurality of the coil springs are arranged in an axial direction of the fixing roller. With this configuration, it is possible to adjust the left-right balance of the pressure applied to the fixing roller by the sheet-shaped pressing member.

The invention according to claim 7 is characterized in that the entire back surface of the sheet-shaped pressing member is urged by the sponge member. With this configuration, the temperature of the entire sheet-shaped pressing member can be stabilized by the heat storage property of the sponge member.

The invention according to claim 8 is the invention according to claims 1 to 7
A fixing device according to any one of the preceding claims. With such a configuration, it is possible to realize a quick start-up and a cost reduction by reducing the number of components related to the fixing device.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a side view showing the internal configuration of a facsimile apparatus having a fixing device according to a first embodiment of the present invention, wherein 1 is a main body of the facsimile apparatus, and 2 is detachably mounted on the main body 1. A process cartridge accommodating various process devices for forming an image by an electrophotographic process; 3, a photoconductor provided in the process cartridge 2; and 4, a laser beam scanned on the photoconductor 3 by a laser beam modulated based on image data. An optical writing device 5; a paper feed cassette 5 for storing recording paper; 6 a paper feed roller for feeding recording paper from the paper feed cassette 5; A transfer roller for transferring the toner image formed on the recording paper; a fixing device for fixing the toner image on the recording paper; a paper discharge roller; a contact sensor;
3 shows a document table formed on the upper surface of the document.

The original set on the original placing table 11 is transported by the transport system, passes through the contact sensor 10, and is discharged to the outside. When a document passes through the contact sensor 10, an image of the document is optically read by the contact sensor 10. The image data read by the contact sensor 10 or the image data input from the outside is sent to the optical writing device 4, and the optical writing device 4 uniformly charges the laser beam modulated based on the image data. By irradiating the surface of the photoconductor 3, an electrostatic latent image is formed.
The toner is attached to the electrostatic latent image to form a toner image, and the toner image is transferred to recording paper by the transfer roller 7.
Then, the toner image is fixed on the recording paper by pressing / heating by the fixing device 8, and is discharged to the outside by the discharge roller 9.

FIG. 2 is an explanatory view showing the structure of the fixing device according to the first embodiment of the present invention. FIG. 2A is a side view, and FIG.
FIG. 2B is a front view, FIG. 2 is a side view showing the configuration of the fixing device, 12 is a fixing roller, 13 is a sheet-shaped pressing member, 14 is a heating source provided inside the fixing roller 12,
Reference numeral 15 denotes a guide plate for guiding the recording paper to the fixing device 8;
Indicates a coil spring, and 21 indicates a pressure adjusting mechanism.

A heating source 14 is provided inside the fixing roller 12, and as the heating source 14, an infrared heater, a halogen heater, an induction heater, a sheet heater, or the like is used. The sheet-shaped pressing member 13 has a plate spring property and is made of a metal plate having high heat conductivity, for example, a stainless steel or copper plate.

A portion of the guide plate 15 opposed to the fixing roller 12 is formed in a concave shape, and one end of the sheet-shaped pressing member 13 is formed on the edge of the concave portion on the upstream side in the recording paper conveyance direction by a screw or an adhesive. Fixed
The other end of the sheet-shaped pressing member 13 can move up and down as a free end.

FIG. 3 is an explanatory view showing a schematic configuration of the pressure adjusting mechanism shown in FIG. 2. Reference numeral 22 denotes a mounting plate for mounting one end of a coil spring 20, reference numeral 23 denotes a pedestal having a thread formed on a side surface,
Reference numeral 4 denotes a screw hole formed at one end of the coil spring 20 at a mounting position, and reference numeral 25 denotes a solenoid that moves the mounting plate 22 up and down.

A pedestal 23 is screwed into the screw hole 24, and one end of the coil spring 20 is placed on the pedestal 23. Then, the pedestal 23 is moved up and down by rotating the pedestal 23 using an instrument such as a driver, and the position of one end of the coil spring 20 is changed. 13 can be adjusted.

Further, by driving the solenoid 25 to move the mounting plate 22 up and down, the sheet-like pressing member 13 can be brought into contact with or separated from the fixing roller 12. For example, in the normal state, the sheet-shaped pressing member 1
3 is brought into contact with the fixing roller 12, and after the image forming operation is completed, the solenoid 25 is driven for a predetermined time until the fixing roller 12 is cooled to a predetermined temperature or when a jam occurs, and the sheet-shaped pressing member 13 is driven. Is performed so as to separate the. The drive control of the solenoid 25 is performed by a CPU (not shown).

The position of the fixing roller 12 or the sheet pressing member 13 is set so that the sheet pressing member 13 comes into contact with the fixing roller 12 while applying a predetermined pressure. Therefore, the nip pressure which is the pressure applied by the sheet-shaped pressing member 13 to the fixing roller 12 is determined by the leaf spring property of the sheet-shaped pressing member 13 and the bias from the coil spring 20.

The recording paper conveyed from the transfer roller 7 is guided by a guide plate 15 and passes through a contact portion between the fixing roller 12 and the sheet-shaped pressing member 13, that is, a nip portion. At this time, when the recording paper is pressed / heated, the toner image on the recording paper is melted and fixed on the recording paper, and the guide plate 15 and the paper discharge roller 9 (see FIG. 1)
Is discharged to the outside through

According to the first embodiment configured as described above, since the pressure can be adjusted by the individual coil springs 20, the left and right balance of the pressure applied from the sheet-shaped pressing member 13 can be adjusted. become. Further, since the sheet-shaped pressing member 13 can be brought into contact with / separated from the sheet-shaped pressing member 13, it is possible to easily process jammed paper. Further, by urging the free end of the sheet-shaped pressing member 13, it is possible to secure a nip width between the fixing roller 12 and the sheet-shaped pressing member 13.

Further, since the sheet-shaped pressing member 13 is formed of a metal plate, the heat conductivity of the sheet-shaped pressing member 13 is improved, so that the sheet-shaped pressing member 13 is heated quickly. As a result, the recording paper can be stably heated in the nip portion, thereby preventing the recording paper from waving. Further, by using a copper plate as the metal plate constituting the sheet-shaped pressing member 13, it is possible to warm up more quickly, and by using a stainless steel plate, it is possible to improve workability and durability.

According to the first embodiment, three coil springs 20 are used. However, the number, type and arrangement of the coil springs 20 may be appropriately set.

Further, a coating layer made of a fluororesin (PFA, PTFE, FEP, etc.) may be formed on the surface of the sheet-shaped pressing member 13. As a result, by smoothing the surface of the sheet-shaped pressing member 13, it is possible to reduce the frictional force applied to the recording paper, and moreover, it becomes difficult for toner to adhere to the surface of the sheet-shaped pressing member 13. Is prevented from remaining on the recording paper, and as a result, the back stain of the recording paper can be prevented.

The length of the sheet-shaped pressing member 13 in the recording paper transport direction is increased so that the position of the free end is located downstream of the nip portion in the recording paper transport direction. Since the edge of the free end of the sheet-shaped pressing member 13 does not contact the fixing roller 12, the surface of the fixing roller 12 is not damaged by the sheet-shaped pressing member 13. Further, it is possible to reduce the occurrence of recording paper jam caused by the recording paper being caught on the burrs at the free end of the sheet-shaped pressing member 13.

FIG. 4 is an explanatory view showing the structure of a fixing device according to a second embodiment of the present invention. Reference numeral 30 denotes a heat-resistant sponge.

In the device of the second embodiment, a sponge 30 is provided on the entire portion of the sheet-shaped pressing member 13 and the main body 1 in place of the coil spring 20 and the pressure adjusting mechanism 21 in the configuration shown in FIG. It is provided. Since the sponge 30 is arranged in a compressed state between the sheet-shaped pressing member 13 and the main body 1, the sheet-shaped pressing member 13 is urged toward the fixing roller 12.

According to the second embodiment configured as described above, the heat storage property of the sponge 30 causes the sheet-shaped pressing member 1
3 can be stabilized.

It is not necessary that the sponges 30 are all made of the same material. For example, the nip width can be secured by lowering the flexibility of the sponge 30 on the downstream side in the recording paper conveyance direction with respect to the nip portion. .

Although the present embodiment has been described above, the present invention is not limited to the above-described embodiment.
For example, by chamfering the free end of the sheet-shaped pressing member 13 so as to have a curved surface, the sheet-shaped pressing member 13
It is possible to prevent the recording paper from being caught on the free end of the recording medium and causing conveyance failure.

[0038]

According to the present invention as described above, the sheet-like pressing member can stably press the fixing roller, and the nip width can be stably secured. it can. As a result, the thermal conductivity of the sheet-shaped pressing member is improved, so that the sheet-shaped pressing member can be quickly warmed.

[Brief description of the drawings]

FIG. 1 is a side view showing an internal configuration of a facsimile apparatus having a fixing device according to a first embodiment of the present invention.

FIG. 2 is a side view showing the configuration of the fixing device according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a schematic configuration of a pressure adjusting mechanism in FIG. 2;

FIG. 4 is an explanatory diagram illustrating a configuration of a fixing device according to a second embodiment of the present invention.

FIG. 5 is a side view showing the internal structure of a conventional fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 2 Process cartridge 3 Photoreceptor 4 Optical writing device 5 Paper supply cassette 6 Paper supply roller 7 Transfer roller 8 Fixing device 9 Discharge roller 10 Adhesion sensor 11 Original mounting table 12 Fixing roller 13 Sheet pressing member 14 Heat source 15 Guide plate 20 Coil spring 21 Pressure adjustment mechanism 22 Mounting plate 23 Pedestal 24 Screw hole 25 Solenoid 30 Sponge

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hidehiko Fujiwara 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H033 BB17 BB33 BB34 BB39 2H071 BA03 BA16 BA29 DA12

Claims (8)

[Claims] 1. A fixing roller having a heat source therein, and a sheet-shaped pressing member which abuts the fixing roller while applying a predetermined pressure, wherein the recording paper on which a toner image has been transferred is fixed to the fixing roller. A fixing device for fixing a toner image on recording paper by applying pressure / heating when passing between a roller and the sheet-shaped pressing member, wherein the fixing device is disposed between the sheet-shaped pressing member and a main body. And a biasing member for biasing the sheet-shaped pressing member toward the fixing roller is provided. 2. The fixing device according to claim 1, wherein the urging member is a coil spring. 3. The fixing device according to claim 1, wherein the urging member is a sponge member. 4. The sheet-like pressing member according to claim 1, wherein the urging force of the urging member is applied to a portion of the sheet-like pressing member other than a contact portion with the fixing roller. Fixing device. 5. A mechanism for changing the position of the other end of the coil spring by attaching one end of the coil spring to the sheet-shaped pressing member and the other end to the main body side, wherein the urging member is a coil spring. The fixing device according to claim 2, wherein the fixing device is provided. 6. The fixing device according to claim 5, wherein a plurality of the coil springs are arranged in an axial direction of the fixing roller. 7. The fixing device according to claim 3, wherein the entire back surface of the sheet-shaped pressing member is urged by the sponge member. 8. An image forming apparatus comprising the fixing device according to claim 1. Description: