JPH10228196A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the frictional force between a fixing belt and a pressure pad and to prevent the staining of a recording sheet and a peripheral device by coating the inner surface of the fixing belt with a lubricant through a lubricant holding member arranged along the pressure pad. SOLUTION: The pressure pad 56 of a heat-resistance elastic member, one of the pressure member 53 extended in the axial direction of a heating roll 51 is pressed toward the heating roll 51 whose surface has an elastic layer 51b. Then, an endless belt-like fixing belt B supported to be revolvable around the pressure member 53 and a belt guide 59 adjacently arranged in parallel with the pressure member 53 is bought into press-contact with the surface of the heating roll 51 by the pressure member 53. At this time, the inner surface of the fixing belt B is coated with the lubricant by the lubricant holding member 57 supported by the pressure member 53 and arranged along the pressure pad 56. When the inner surface of the fixing belt B is coated with the lubricant, the frictional resistance between the pressure pad 56 and the fixing belt B becomes low, wearing, damage, etc., are reduced and the fixing belt B can stably travel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an electrophotographic copying machine.
The present invention relates to a fixing device that fixes an unfixed toner image on a recording sheet, such as a printer, to the recording sheet by heating and pressing.

2. Description of the Related Art In recent years, a fixing device of an electrophotographic copying machine or a printer has been required to be reduced in size and further reduced in power consumption as the size of the entire machine is reduced. To this end, it is essential to obtain good fixing performance at lower temperature and pressure and to shorten the warm-up time. Conventionally, the following techniques (J01) and (J02) are known as specific means.

(J01) (Technology for fixing an unfixed toner image on a recording sheet passing between a pressure film and a fixing film sandwiched between a heating element and a pressure roll) The recording sheet is passed between the pressure roller and the surface of the fixing film where the heat generating portion contacts the rear surface (inner surface) to fix the toner image on the recording sheet. Since the fixing film is thin, the time required for heating to a temperature necessary for fixing is short, and the warm-up time is shortened. However, in the above-described configuration, it is difficult to maintain the fixing temperature at an appropriate constant temperature when forming an image with a large amount of toner in a full-color machine using a plurality of color toners. When low-temperature fixing or high-temperature fixing is performed, low-temperature offset or high-temperature offset is likely to occur, and it becomes difficult to separate the fixing film and the toner at the exit of the fixing nip.

(J02) (Technique for pressing a fixing belt against a heating roll by a pressure pad) This technique is a technique in which a fixing belt is coated with a heat-resistant elastic material having excellent toner release properties on a surface thereof by a pressure pad. A technique has been proposed in which a recording sheet is passed between the fixing belt and the heating roll by applying pressure to the heating roll and forming a wide fixing nip width. This technology (J02)
Is that the length of the pressure pad in the belt conveyance direction and the fixing nip width (the length in the belt conveyance direction) can be increased, and the recording sheet surface contacts the heating roll during the time when the recording sheet passes through the fixing nip width. Therefore, since the fixing time is longer than that of (J01), it is easy to perform appropriate fixing. However, in both of the prior arts (J01) and (J02), the fixing film or the fixing belt slides on the heat generating portion and the pad portion of the heat generating element, respectively. Due to the sliding resistance due to the friction, the running of the fixing film or the fixing belt becomes unstable, and paper wrinkles are generated. In order to solve this problem, the following technology (J03) is conventionally known. (J03) (Technique described in JP-A-2-77776) In this publication, a lubricant application member is provided on the delivery side of the fixing film.

[0004]

The prior art (J0)
In 3), there is a problem similar to the problem described in the prior art (J01). Further, a lubricant application member is provided on the delivery side of the fixing film. However, since the heating film of the heating element slides with the fixing film, the lubricant applied to the fixing film is scraped at the entrance of the heating element. As a result, there is a problem that excess lubricant leaks out of the fixing film and stains the recording sheet and the apparatus.

In view of the above circumstances, the present invention has the following (O0
1) and (O02) are to be described. (O01) In a fixing device for allowing a recording sheet to pass between a heating roll on which the fixing belt is pressed by a pressing pad and the fixing belt, the frictional force between the fixing belt and the pressing pad is reduced. (O02) To prevent the recording sheet and peripheral devices from being stained by a lubricant applied to the inner surface of the fixing belt to reduce the frictional force.

[0006]

Means for Solving the Problems Next, in order to solve the above-mentioned problems, the present invention will be described. However, the elements of the present invention facilitate the correspondence with the elements of the embodiments described later. For,
The reference numerals in parentheses indicate the elements of the embodiments.
The reason why the present invention is described in correspondence with the reference numerals of the embodiments described below is to facilitate understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

(Solution of the Invention) In order to solve the above-mentioned problems, a fixing device of the invention has the following requirements: (A01) an elastic layer (51b) on the surface, Heating roll (51), both ends of which are supported, (A02) A pressure pad (56) made of a heat-resistant elastic member that extends in the axial direction of the heating roll (51) and is pressed toward the heating roll (51). (A) a pressure member having a pad support member (54) for supporting the pressure pad (56);
03) The pressure pad (56) and the pressure pad (5)
6) Belt guide (59) arranged adjacent and parallel to
An endless fixing belt (B) whose outer surface is pressed against the surface of the heating roll (51) by the pressure pad (56) which is rotatably supported around the periphery of the heating roll and which is pressed against the inner surface;
(A04) a fixing nip (N) is formed by a pressure contact area between the fixing belt (B) and the heating roll (51);
The heating roll (51) for fixing an unfixed toner image adhered to a recording sheet passing through the fixing nip (N), the fixing belt (B), and the pressure member (53);
(A05) A lubricant holding member (5) supported by the pressure member (53) and arranged along the pressure pad (56) to apply a lubricant to the inner surface of the fixing belt (B).
7).

(Function of the Present Invention) In the fixing device of the present invention having the above-described configuration, the pressure pad (5) made of a heat-resistant elastic member of the pressure member (53) extending in the axial direction of the heating roll (51).
6) is pressed toward a heating roll (51) having an elastic layer (51b) on the surface. The endless fixing belt (B) rotatably supported around the pressure member (53) and a belt guide (59) disposed adjacent to and parallel to the pressure member (53). The pressure member (53) is pressed against the surface of the heating roll (51). A fixing nip (N) is formed by the pressure contact area between the fixing belt (B) and the heating roll (51). The unfixed toner image (I) attached to the recording sheet (S) is fixed when passing through the fixing nip (N).

At this time, a lubricant holding member (57) supported by the pressure member (53) and arranged along the pressure pad (56) is provided on the inner surface of the fixing belt (B) with a lubricant. Is applied. When the lubricant is applied to the inner surface of the fixing belt (B), the frictional resistance between the pressure pad (56) and the fixing belt (B) is reduced, and their wear, damage, etc. are reduced, and the lubricant is stable. A fixing device with less running and wear of the fixing belt (B) can be obtained. Further, in the present invention, since the nip is formed by the heating roll (51) and the fixing belt (B), the nip width is different from the case where the nip is formed by the fixing film and the pressure roll which the heating member contacts. Can be taken widely. Therefore, appropriate fixing can be easily performed even if the amount of toner increases or decreases. Therefore, even when the amount of toner is large, such as in a full-color image, appropriate fixing can be performed, and offset is unlikely to occur.

[0010]

(Embodiment 1) Embodiment 1 of a fixing device of the present invention is as follows.
(A06) The lubricant holding member disposed in the vicinity of an upstream side of the pressure pad (56) pressed against the inner surface of the fixing belt (B). (57). (Operation of the First Embodiment) In the first embodiment of the fixing device of the present invention having the above-described configuration, the lubricant holding member (57) has the pressure pad (57) pressed against the inner surface of the fixing belt (B). 56), the lubricant is applied to the fixing belt (B). Therefore, the pressure pad (5
When the lubricant is scraped off and accumulated near the upstream side by 6), the accumulated lubricant is collected by the lubricant holding member (5) on the upstream side.
7), the accumulated lubricant does not leak from the pressure belt (56) and stain the recording sheet (S) and surrounding devices.

Next, specific examples (embodiments) of the embodiment of the rotary polygon mirror of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples. (Embodiment) FIG. 1 is an overall explanatory view of an image forming apparatus provided with a fixing apparatus according to an embodiment of the present invention. In FIG. 1, an image forming apparatus U includes a digital copying machine U1 as an image forming apparatus main body having a platen glass (transparent document table) A1 on an upper surface, and an automatic original detachably mounted on the platen glass A1. A transport device U2 is provided. The automatic document feeder U2 sequentially takes out the documents Gi (i = 1, 2,...) Stored in the document feed tray TRk, transports the documents Gi to the copy position on the platen glass A1, and transfers the copied document. The document is discharged to the document discharge tray TRh. Also, the automatic document feeder U2 includes a document presence sensor S1 for detecting the presence of a document on the document feed tray TRk,
An original registration sensor S2 for detecting passage of the original to be conveyed is provided.

The copying machine body U1 has a UI (user interface) disposed on the upper surface thereof, and an I (document reading device) sequentially disposed below the platen glass A1.
It has an IT (Image Input Terminal), an IPS (Image Processing System), and an IOT (Image Output Terminal) as an image recording operation unit. The UI (user interface)
An input operation member (not shown) such as a copy start button, a copy setting number input key, etc., by which a user of the image forming apparatus U inputs an operation command signal such as a copy start, and information on a current setting state of the image forming apparatus U. And a display unit (not shown) for performing the display or the like.

An IIT as an original reading device disposed below the transparent platen glass A1 on the upper surface of the copying machine main body U1.
Is the OP located at the platen registration position (OPT position)
A T registration sensor (platen registration sensor) Sp and an exposure optical system 1 are provided. The exposure optical system 1 has a lamp unit 2 mounted on a full-rate carriage, and the lamp unit 2 has an exposure lamp 3 and a second mirror 4. Further, the exposure optical system 1 has a mirror unit 5 mounted on a half-rate carriage that moves at half the speed of the full-rate carriage, and the mirror unit 5 includes a second mirror 6 and a third mirror. 7. The exposure optical system 1 has a lens 8.

Then, the lamp unit 2 moves in the horizontal direction in FIG. 1 in parallel with the document, and the moving mirror unit 5 moves at a speed half the moving speed of the lamp unit 2 and a distance of 1/2. , The distance between the document Gi and the lens 8 is kept constant. During this time, the reflected light of the document Gi illuminated by the lamp 3 passes through the exposure optical system 1 and passes through the CCD (solid-state imaging device). Element).

The IPS (image processing system) has read image data output means 11 for reading electric signals obtained by the CCD and write image data output means 12 for outputting write image data. The read image data output means 11 includes a conventionally known AGC (auto gain control), AOC (auto offset control), ADC (analog-to-digital converter), and the like.

[0015] Write image data output means 12 to which the image data output from the read image data output means 11 is input.
Has a function of performing conventionally known image processing such as enlargement / reduction correction, density correction, and the like on the image data after performing shading correction on the input image data, and temporarily stores the image data. Image memory 13 to be stored in memory
have. The write image data output means 12 outputs the processed image data to the IOT laser drive signal output device 14 as write data. The IOT laser drive signal output device 14 outputs a laser drive signal corresponding to the input image data to an ROS (optical writing scanning device, that is, a latent image writing device). The ROS is controlled by an electrostatic latent image writing position Q on the rotating image carrier 16 by a laser beam L modulated by the input laser drive signal.
Scan 1 A charger 17 for uniformly charging the image carrier 16 is disposed along the rotating image carrier 16 and upstream of the latent image writing position Q1 in the moving direction of the image carrier 16. After the image carrier 16 is uniformly charged by the charger 17, an electrostatic latent image is written by the laser beam L at the latent image writing position Q1.

A developing device 18 is arranged around the image carrier 16 along the rotational direction thereof, downstream of the latent image writing position Q1, at a developing position Q2, and a transfer device at a transfer position Q3. 19, and a cleaner unit 20 is further disposed downstream thereof. Further, the rotating image carrier 1
Along the line 6, downstream of the transfer position Q3, a toner image density sensor SNd is arranged. The toner image density sensor SNd is composed of a light emitting element and a light receiving element disposed in the vicinity of the image carrier 16, and is a toner image (patch) formed by developing a test electrostatic latent image formed on the image carrier 16. ) Is measured to detect the toner image density.

The copier body U1 has a first paper feed tray T1 for storing paper and a second
A paper tray T2, an intermediate tray T0 for temporary stock used for double-sided copying, a third paper tray T3, a fourth paper tray T4, and a fifth paper tray T5 for storing a large amount of paper are detachably stored. Have been. The intermediate tray T0 is a tray used when circulating the recording sheet (hereinafter referred to as a sheet) S on which the first copy has been performed at the time of double-sided copying or multiple copying, and retransmitting the recording sheet S to the transfer position Q3.

At the upper right side of the first paper feed tray T1, a manual feed tray 21 is provided. The paper conveyed from the manual feed tray 21 by the paper supply rolls R6 and R7 and the papers sent out from the paper supply trays T1 to T5 are conveyed to the transfer position Q3 through the first sheet conveyance path 22. It has become so. The sheet conveyed in the first sheet conveying path 22 is detected by the sheet registration sensor SNy. At the end of the first sheet conveying path 22, a registration gate 23 for temporarily stopping the recording sheet S conveyed to the upstream side of the transfer position Q3 in the sheet conveying direction and then carrying the recording sheet S to the transfer position Q3 is provided. And a registration roll 24. The transfer device 19 disposed at the transfer position Q3 transfers the toner image on the surface of the image carrier 16 to the recording sheet S passing through the transfer position Q3. The transfer position Q3
After the toner remaining on the surface of the image carrier 16 that has passed through is collected by the cleaner unit 20, the charger 17 uniformly charges the surface again.

The recording sheet S on which the toner image has been transferred at the transfer position Q3 is conveyed to a fixing position Q4 through a conveyance belt 26 of a second sheet conveyance path 25 connected to a discharge tray TR. A fixing device F is disposed at the fixing position Q4, and is configured to fix an unfixed toner image I (see FIG. 2) on the recording sheet S passing through the fixing position Q4 by applying heat and pressure. A discharge roll 29 is provided in the second sheet transport path 25 downstream of the fixing position Q4. The discharge roll 29 discharges the sheet from the discharge port 30 to the discharge tray TR.

In the second sheet conveying path 25, a switching gate 31 is disposed upstream of the discharge roll 29.
The switching gate 31 is used when switching the transport direction of the recording sheet S on the second sheet transport path 25 to the sheet circulation path 32 or the direction of the discharge tray TR. The sheet circulation path 32 is connected to a sheet reversing path 33 and the intermediate tray T0 via a switching gate. The switching gate 34 directs the recording sheet S of the sheet circulation path 32 to the sheet reversing path 33 when performing double-sided copying, and directly to the intermediate tray T0 when performing multiple copying. The sheet-shaped and comb-shaped mylar gate 36 provided in the sheet reversing path 33 allows the recording sheet S to move downward by elastic deformation when the passing recording sheet S is conveyed downward, When the recording sheet S that has passed the mylar gate 36 is switched back and conveyed upward, the recording sheet S is configured to be guided in the direction of the intermediate tray T0. The recording sheet S once stored in the intermediate tray T0 is moved from the intermediate tray T0 to the first
The sheet is conveyed to the transfer position Q3 again by the sheet conveying path 22.

Next, the fixing device F arranged at the fixing position Q4 will be described. FIG. 2 is an explanatory view of an embodiment of the fixing device of the present invention, and is an enlarged sectional view of the fixing device shown in FIG. FIG. 3 is a sectional view taken along the line III-III of FIG. FIG.
In FIG. 3, a fixing device F disposed at the fixing position Q4 includes a heating roll 5 extending perpendicularly to the recording sheet S conveyance direction.
One. The heating roll 51 has a metal cylindrical member 51a and an elastic layer 51b formed on the surface thereof. A heater (heating element) 51h is built in the cylindrical member 51a. Note that such a heating roll 51 is conventionally known. A release agent application roll 52 is in contact with the heating roll 51. The release agent applying roll 52 has a function of applying the release agent to the elastic layer 51b of the heating roll 51 by gradually releasing the release agent contained in the cylindrical member to the surface.

A pressing member 53 is provided below the heating roll 51.
Is arranged. The pressing member 53 is provided with the heating roll 51.
And a pressure pad 56 made of a heat-resistant elastic member provided on a surface of the pad support member 54 facing the heating roll 51. The pad support member 54 has a strain generating portion 54a formed of a rigid body immediately downstream of a pressure contact area where the heating roll 51 is pressed.
And a recess 54b. The downstream side of the distortion generating portion 54a is a curved surface, and the upper end surface thereof is the pad supporting member 54a.
Is formed higher than the upstream side of the heating roll 51, and is configured to form distortion on the surface of the heating roll 51 when pressed against the heating roll 51. A pressure pad 56 is housed downstream of the recess 54b.

On the upstream side of the concave portion 54b of the pad support member 54, a heat resistant material (for example,
A lubricant holding member 57 made of felt made of aramid fiber is accommodated. As the lubricant impregnated and held in the lubricant holding member 57, a heat-resistant lubricant (for example, silicon-based or fluorine-based oil or grease) is used.
The lubricant holding member 56 is fixed in the concave portion 54a with a heat-resistant adhesive or a double-sided tape. A belt guide 59 having an arc surface is connected to the lower end of the pad support member 54 via a connecting member 58 (see FIG. 2). Belt end guide members 61 are provided at both ends of the pad support member 54. The pad supporting members 54 are compression springs 62, 6 whose both ends in the rotation axis direction press the lower surfaces of the belt end guide members 61, 61 upward.
2 and is pressed toward the heating roll 51. An endless fixing belt B is rotatably supported around the pad support member 54 and the belt guide 59. Movement of both ends of the fixing belt B is regulated by the belt end guide members 61, 61.

As a result, a load is applied to the pad supporting member 54 at both ends by the compression springs 62, 62, and the pressing pad 5 on the pad supporting member 54 sandwiches the fixing belt B.
6 is configured to be pressed against the heating roll 51. The pressing pad 56 of the pressing member 53 presses the fixing belt B from the lower surface side to the surface of the heating roll 51 at the fixing position Q4. Therefore, the upper surface of the fixing belt B is pressed against the heating roll 51 at the fixing position Q4. A fixing nip N is formed by the pressure contact area between the heating roller 51 and the fixing belt B at the fixing position Q4.

(Operation of the present embodiment) Each recording sheet S sent from the manual feed tray 21 or each of the paper feed trays T1 to T5 passes through the first sheet conveying path 22 and passes through the transfer position Q3. The toner image on the image carrier 16 is transferred to the sheet S by the transfer device 19. The recording sheet S to which the toner image has been transferred is conveyed to the fixing position Q4 through the second sheet conveying path 25.

In FIG. 2, the recording sheet S conveyed to the fixing position Q4 and passing through the fixing nip N is pressed by the pressing member 53 between the fixing belt B and the heating roll 51 and the heat of the heating roll 51. Thus, the unfixed toner image I on the recording sheet S is fixed. Since the fixing nip N is formed by the heating roll 51 and the fixing belt B, the width of the fixing nip can be widened unlike the case where the fixing nip is formed by the fixing film and the pressure roll. Therefore, appropriate fixing can be easily performed even if the amount of toner increases or decreases. Therefore, even when the amount of toner is large, such as in a full-color image, appropriate fixing can be performed, and offset is unlikely to occur. At the time of the fixing, the lubricant holding member 57 that contacts the inner side surface (back surface) of the fixing belt B applies a lubricant. The friction resistance between the pressure pad 56 and the fixing belt B is reduced by the applied lubricant. Therefore, abrasion, damage, and the like of the pressure pad 56 and the fixing belt B are reduced, and a long-life fixing device can be obtained. When the applied lubricant is scraped off by the pressure pad 56 and stays, the lubricant that has moved upstream is absorbed by the lubricant holding member 57. For this reason, since the retained lubricant does not leak from the inner side surface of the fixing belt B as in the related art, it is possible to prevent the recording sheet passing through the surface of the fixing belt and the surrounding devices from being stained.

(Modifications) Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, but falls within the scope of the present invention described in the appended claims. Thus, various changes can be made. Modified embodiments of the present invention will be exemplified below. (H01) The present invention is also applicable to a full-color image forming apparatus.

The fixing device according to the present invention has the following effects. (E01) In a fixing device that passes a recording sheet between a heating roll on which a fixing belt is pressed by a pressing pad and the fixing belt, the frictional force between the fixing belt and the pressing pad can be reduced. . (E02) It is possible to prevent the recording sheet and peripheral devices from being stained by the lubricant applied to the inner surface of the fixing belt to reduce the frictional force.

[Brief description of the drawings]

FIG. 1 is an overall explanatory diagram of an image forming apparatus including a fixing device according to an embodiment of the present invention.

FIG. 2 is an explanatory view of an embodiment of the fixing device of the present invention, and is an enlarged sectional view of the fixing device shown in FIG.

FIG. 3 is a sectional view taken along the line III-III of FIG. 2;

[Explanation of symbols]

B: fixing belt I: unfixed toner image, N: fixing nip, S: recording sheet 51: heating roll, 51b: elastic layer, 53: pressing member,
56: pressure pad, 57: lubricant holding member, 59: belt guide

Claims (2)

[Claims] 1. A fixing device having the following requirements: (A01) a heating roll having an elastic layer on its surface and having both ends supported in the axial direction; and (A02) an axial direction of the heating roll. A pressure member made of a heat-resistant elastic member that extends toward the heating roll and is pressed toward the heating roll; and a pad supporting member that supports the pressure pad. An endless fixing belt that is rotatably supported around a belt guide disposed adjacent to and parallel to the pad and whose outer surface is pressed against the surface of the heating roll by the pressure pad that presses against the inner surface; (A04 A) a fixing nip formed by the pressure contact area of the fixing belt and the heating roll, and the heating roll, the fixing belt, and the fixing belt for fixing an unfixed toner image attached to a recording sheet passing through the fixing nip. Fine said pressure member, (A05) the disposed along and the pressure pad is supported on the pressure member, the lubricant holding member for applying the lubricant to the inner surface of the fixing belt. 2. The fixing device according to claim 1, wherein the lubricant satisfies the following requirements: (A06) the lubricant disposed near an upstream side of the pressure pad that presses against the inner surface of the fixing belt. Holding member.