JP2003076209A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device for a fixing device which has a compact and simple configuration and prevents the temperature up of the non-paper- feeding part of a rotating body and the temperature drop of the boundary part at the paper-feeding part. SOLUTION: A pair of rotating bodies Fh and Fp which form a fixing region Q5 by a region pressed by them have a heat source at least in one rotating bodies Fh and Fp. The fixing device is provided with a fixing device F which thermally fixes a toner image when a transfer material having the toner image passes through the fixing region Q5, and a cooling device 42 which has a duct 36 for cooling the non-paper feeding region having an opening 36a and a fan 35 to send cooling air to the duct 36 for cooling the non-paper feeding region in order to cool a non-paper feeding region W1b through which a small width transfer material does not pass when the small width transfer material with a width smaller than that of a maximum width transfer material having the maximum width in the axial direction of a pair of rotating bodies Fh and Fp passes through the fixing region Q5, wherein the opening 36a has an opening area large in the central part along a width direction, and small at both ends in the axial direction.

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 electrophotographic image forming apparatus such as a copying machine, a printer and a facsimile, and more particularly to a heating rotary member for forming a fixing area by a pressure contact area which is pressed against each other while rotating. The present invention also relates to a fixing device that has a pressure rotating member and heats and fixes the unfixed toner image when the transfer material on which the unfixed toner image is formed passes through the fixing region.

[0002]

2. Description of the Related Art Conventionally, as a fixing method for fixing an unfixed toner image on a sheet (transfer material) in the image forming apparatus, the unfixed toner image on the sheet is heated and melted for safety and fixability. A heat fixing method of fixing to a sheet is generally used. Further, due to its good thermal efficiency and ease of downsizing, the unfixed toner image on the paper is heated and pressurized in the fixing area where the heating roll (heating rotary member) and the pressure roll (pressurizing rotary member) are in pressure contact with each other. The hot roll method of fixing is most often used.

FIG. 11 is a sectional view of a conventional heating roll and pressure roll. FIG. 12 is a view for explaining the relationship between the heating roll and the pressure roll and the paper size as seen from the XII direction in FIG. FIG. 13 is a view for explaining the temperature distribution of the heating roll shown in FIG. In FIG. 11, the fixing device has a heating roll Fh and a pressure roll Fp, and the heating roll Fh has a rubber elastic layer 0 on the outer periphery of a core 01 of a metal roll.
2 is formed, and the releasable resin layer 0 is formed around the elastic layer 02.
3 is formed. A heating source 04 such as a halogen lamp is provided inside the core 01. The pressure roll Fp has a rubber elastic layer 06 formed on the outer periphery of the core bar 05 of the metal roll, and a releasable resin layer 07 formed on the outer periphery of the elastic layer 06. A fixing region Q5 is formed by the pressure contact region between the heating roll Fh and the pressure roll Fp. The sheet on which the toner image is formed is heated and pressed in the fixing area Q5, and the toner image is fixed on the sheet.

In the following description, as shown in FIG. 12, when sheets of different sizes are conveyed in the fixing area Q5, one side of each sheet is conveyed so as to always pass through a predetermined line (reference line). The case (one-sided reference) will be described. In FIG. 12, the maximum size paper that passes through the fixing area Q5 is A4LEF paper (paper that is conveyed with the long edge of the A4 size paper as the front end), and the paper having a width smaller than the maximum size paper is small size paper. , Especially B5
SEF (paper conveyed with the short edge of B5 size paper as the front end) is the minimum size paper. Then, when the A4LEF paper passes through the fixing area Q5, the width of the fixing area Q5 through which the paper passes (the width of the maximum size paper passing area) is W0. Width W of the paper passing area of this maximum size paper
0 is set to be the same as the width of the fixing area Q5.

Further, in FIG. 12, the width of the fixing area Q5 (the small size paper is passed) through which the small size paper having a width smaller than the A4LEF paper (the maximum size paper) (for example, the B5SEF paper having the smallest width) passes. It is assumed that the width of the area) is W1a and the width of the fixing area Q5 where the small size paper does not pass (the width of the non-sheet passing area of the small size paper) is W1b. Further, when paper of various sizes passes through the fixing area, the fixing area where the paper passes, the fixing area other than the paper passing area is called the non-paper passing area, and the paper passing area when rotating is referred to as the paper passing area. The surface portion of the heating roll passing therethrough is referred to as the paper passing area passing surface, and the surface portion of the heating roll passing through the non-paper passing area during rotation is referred to as the paper passing area passing surface.

As shown by the solid line in FIG. 13, the A4LE
When fixing F paper (maximum size paper) in the fixing area Q5,
The surface of the heating roll Fh passing through the paper passing area has a substantially uniform temperature distribution. However, when B5SEF paper, which is a small size paper having a width smaller than that of the A4LEF paper (maximum size paper), is continuously fixed in the fixing area Q5, when cooling air is not blown to the non-paper passing area passing surface of the heating roll Fh, As indicated by the dotted line 13 in FIG. 13, the temperature of the non-sheet passing area passing surface of the heating roll Fh rises excessively. This is because when small-size paper is continuously passed, heat is partially stored in the non-paper-passage area W1b where the paper does not pass, because heat is not absorbed by the paper.

The following publication (J01) is known as a description of a conventional technique for preventing a temperature rise in the non-sheet passing area. (J01) Japanese Patent Application Laid-Open No. 60-136779 DISCLOSURE OF THE INVENTION According to the technique described in this publication, the periphery of the pressure roll in the fixing device is divided into a sheet passing area side and a non-sheet passing area side by a partition plate, and the inside of the fixing apparatus is provided. Cooling air is blown from the arranged cooling fan to the outer peripheral member of the pressure roll on the non-sheet passing area side.

Further, the following publication (J02) is known as a description of a conventional technique for preventing the temperature rise in the non-sheet passing area. (J02) Japanese Patent Application Laid-Open No. 5-181382 In FIG. 1, which is an explanatory view of the first embodiment of this publication (J02), a cooling fan 4 is arranged above a top plate 5 which covers above the fixing roll 1 and is normally provided. Air is blown to the upper side of the top plate 5 to prevent the temperature rise around the fixing device, and when the paper passing through the fixing area is a small size paper, the window 6 as a guide device provided on the top plate 5 is opened, and Cooling air is blown to the surface portion of the fixing roll 1 that rotates through the paper passing area. In the third embodiment shown in FIGS. 6 and 7 of this publication (J02), the fixing roll 1 and the pressure belt 10 are used, and the cooling air is blown to the duct 12 arranged so as to penetrate the inside of the pressure belt 10. The cooling air is made to flow from the window 6 provided in the middle of the duct toward the non-sheet passing area of the pressure belt 10 toward the end thereof. According to the technique of this publication (J02), the cooling air is blown from the boundary portion of the non-sheet passing area to the end of the non-sheet passing area, so that the non-sheet passing area of the fixing roll 1 is not passed. It is possible to prevent the occurrence of defective fixing due to a temperature decrease near the boundary with the area.

[0009]

(Problems of the technique described in (J01)) In the conventional technique described in this publication (J01), since a cooling fan is provided inside the fixing device, a cooling fan having high heat resistance is used. Because it has to be done, the cost increases. Further, in the technique described in this publication, a cooling fan with a relatively large air flow is required, and the fixing device itself becomes large. Even if a partition plate is provided, cooling air flows into the paper passing area from the non-paper passing area side, and the temperature decreases near the boundary between the paper passing area and the non-paper passing area, which is indicated by the one-dot chain line in FIG. The temperature distribution is as follows. In this case, there is a problem that the fixing temperature becomes low and the fixing becomes defective.

(Problems of the technology described in (J02)) In the technology described in (J02), cooling air is blown from an opening formed in an outer wall of a case for a fixing device that accommodates a fixing rotation member inside. However, the cooling air that flows into the interior through the opening is a small portion, and it is difficult to increase the cooling air that flows from the window 6 to the lower surface of the top plate. Further, since the fixing device case is disposed relatively far from the heating rotary member whose temperature rises, the cooling efficiency of the heating rotary member becomes low. Further, the cooling air flowing out to the inner surface of the pressure belt 10 from the valve 13 provided in the middle of the duct 12 (the duct whose downstream end is open) arranged inside the pressure belt 10 is higher than the cooling air flowing out from the opening at the downstream end. It is considered to be few. Therefore, the cooling air blower described in the publication (J02) cannot efficiently supply the cooling air to the surface portion of the fixing roll (heating roll) that passes through the non-sheet passing area.

In view of the above-mentioned circumstances, the present invention has the following contents (O01) to (O03). (O01) To efficiently prevent the temperature rise in the non-sheet passing area of the fixing rotary member including the heating rotary member and the pressurizing rotary member of the fixing device. (O02) To reduce variations in temperature in the non-sheet passing area. (O03) Prevent temperature drop near the boundary between the non-paper feed area and the paper feed area.

[0012]

The present invention, which has solved the above-mentioned problems, will now be described. Elements of the present invention include elements of the embodiment in order to facilitate correspondence with the elements of the embodiment described later. Add the ones in parentheses to the symbol. Further, the reason why the present invention is described in association with the reference numerals of the embodiments described later is to facilitate understanding of the present invention and not to limit the scope of the present invention to the embodiments.

(Invention) In order to solve the above-mentioned problems, a fixing device of the present invention is characterized by having the following structural requirements (A01) to (A05). (A01) A heating rotation member (Fh) and a pressure rotation member (Fp) that form a fixing area (Q5) by a pressure contact area that is pressed against each other while rotating, and is a transfer material (S) on which an unfixed toner image is formed. ) Passes through the fixing area (Q5), the heating rotary member (Fh) and the pressurizing rotary member (Fp) that heat-fix the unfixed toner image, and (A02) the heating rotary member (Fh) A fixing device case (Fk) housed in (A03) When a small size transfer material having a size in the width direction of the fixing area (Q5) smaller than a maximum size transfer material passes through the fixing area (Q5), The fixing area through which the small-size transfer material passes is defined as (paper passing area W1a), and the paper passing area (W
The fixing area other than 1a) is set as the non-paper passing area (W1b), and the heating rotation member (F) that passes through the non-paper passing area (W1b)
In order to cool the non-sheet passing area passing surface which is the surface portion of h), a non-vent having a blower port (36c, 53c) formed facing the non-sheet passing area passing surface of the heating rotary member (Fh). A cooling device (42, 59) having a paper passage area cooling duct (36, 53) and a blower fan (35, 52) for blowing cooling air to the non-paper passage area cooling duct (36, 53), A04) Connected to the internal ducts (36b, 53b) arranged inside the fixing device case (Fk) and the internal ducts (36b, 53b), and arranged outside the fixing device case (Fk). External duct (36a, 5
3a) and the duct for cooling the non-sheet passing area (36, 5)
3), (A05) The blower fans (35, 52) arranged outside the fixing device case (Fk) and blowing cooling air to the external ducts (36a, 53a).

(Operation of the Present Invention) In the fixing device of the present invention having the above-mentioned structure, the heating rotary member (Fh) and the pressurizing rotary member (Fp) housed inside the fixing device case (Fk).
Means that a fixing area (Q5) is formed by a pressure contact area that is pressed against each other while rotating, and the unfixed toner is formed when the transfer material (S) on which the unfixed toner image is formed passes through the fixing area (Q5). Heat fix the image. The external ducts (36a, 53a) of the non-sheet passing area cooling ducts (36, 53) are arranged outside the fixing device case (Fk), and the external ducts (36a, 53a) have cooling devices (42). , 5
Cooling air (cooling air) is blown from the blowing fan (35, 52) of 9), and the cooling air is the fixing device case (F).
k) The air is blown from the blower ports (36c, 53c) of the internal ducts (36b, 53b) arranged inside to the non-sheet passing area passing surface of the heating rotary member (Fh). The cooling air cools the surface of the heating rotary member (Fh) that passes through the non-sheet passing area, so that it is possible to prevent the temperature of the non-sheet passing area (W1b) from rising. The blower fans (35, 52) for blowing cooling air to the external duct are fixed case (F)
Since it can be arranged outside k), it is not necessary to have a heat resistant structure. The external duct (36a, 53a)
Since the internal ducts (36b, 53b) connected to the internal ducts (36b, 53b) are arranged inside the fixing device case (Fk), the blower vents (36) formed in the internal ducts (36b, 53b).
c, 53c) can be arranged close to the surface of the heating roll (Fh). Therefore, the cooling air (cooling air) can be blown only to the non-paper passing area passing surface of the heating roll (Fh), so that the temperature of the non-paper passing area can be increased without wasting the cooling air. It can be efficiently prevented.

The fixing device of the present invention having the above-mentioned structural requirements (A01) to (A05) can have the following structural requirements (A06). (A06) The blower opening (3) whose opening area is set to be large at the central portion along the width direction and small at both end portions in the axial direction.
6c, 53c). In the fixing device (F) having the above configuration requirement (A06), the opening area of the blower ports (36c, 53c) of the non-sheet passing area cooling ducts (36, 53) is large in the central portion along the width direction. Since it is set to be small at both ends in the axial direction, a large amount of cooling air can be blown to the central portion of the non-sheet passing area (W1b) where the temperature tends to be high, and both ends of the temperature lower than the central portion can be blown. A small amount of cooling air can be sent. Therefore, it is possible to efficiently prevent the temperature rise in the non-sheet passing area.

The fixing device of the present invention having the above-mentioned structural requirements (A01) to (A05) or the above structural requirements (A01) to (A06) can have the following structural requirements (A07). (A07) Transfer material (S) passing through the fixing area (Q5)
Of the rotating member (Fh, Fp) passing through the non-paper passing area (W1) according to the width of the non-paper passing area, the cooling air is blown only to the non-paper passing area passing surface. An opening width adjusting device (41) for adjusting the length in the width direction. In the fixing device (F) of the present invention having the above-mentioned configuration (A07), the opening width adjusting device (41) has the blower opening (36c) according to the width of the transfer material (S) passing through the fixing area (Q5). By adjusting the length in the width direction, the cooling air is blown only to the non-sheet passing area surface. Therefore, even if the transfer material (S) having a different small size passes through the fixing area (Q5) of the fixing rotation member (Fh, Fp), the cooling air is blown only to the non-sheet passing area passing surface. It is possible to prevent the temperature rise in the non-sheet passing area of the rotating members (Fh, Fp).

The above structural requirements (A01) to (A05), the above structural requirements (A01) to (A06) or the above structural requirements (A01)
The fixing device of the present invention including (A07) to (A07) can have the following constituent requirements (A08). (A08) The blower fan including an exhaust fan (52) of an exhaust device (51) for exhausting air inside the image forming apparatus (U1) to the outside. In the fixing device (F) of the present invention having the above configuration requirement (A08), the air exhausted from the exhaust fan (52) of the exhaust device (51) of the image forming apparatus (U1) is a duct for cooling the non-sheet passing area. External duct of (53) (3
6a, 53a). The external duct (36
a, 53a), the air blown to the internal duct (36b,
Air is blown from the blower port (53c) of 53b) to the non-paper passing area passing surface of the heating roll (Fh), and the non-paper passing area (W1b) is cooled. Exhaust device (51) of the image forming apparatus (U1)
When the exhaust fan (52) of No. 3 is used as a blower fan for cooling the non-sheet passing area, a blower fan (3) dedicated to the fixing device (F) is used.
Compared with the case where 5) is provided, the installation space can be reduced and the size can be reduced, and the cost increase can be suppressed.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Next, specific examples (embodiments) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples. (Example) In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction and the left-right direction is the Y-axis.
Axial direction and vertical direction are Z-axis directions, and arrows X, -X, Y,
The directions or sides indicated by -Y, Z, -Z are defined as front, rear, left, right, upper, lower, or front, rear, left, right, upper, lower. Also, in the figure,
"○" in "○" means an arrow from the back of the paper to the front, and "X" in "○" means an arrow from the front to the back of the paper. Shall mean.

(Embodiment 1) FIG. 1 is a vertical sectional view of an image forming apparatus having Embodiment 1 of a fixing device of the present invention. In FIG. 1, the platen glass PG at the upper end of the image forming apparatus U1
An automatic document feeder U2 is placed on the upper surface. The automatic document feeder U2 has a document feed tray TG1 on which a plurality of documents Gi to be copied are stacked and placed. Each of the plurality of documents Gi placed on the document feed tray TG1 is configured to sequentially pass through the copy position on the platen glass PG and be discharged to the document discharge tray TG2. The automatic document feeder U2 has a rear end (-
A hinge shaft (not shown) extending in the left-right direction provided at the (X end) is rotatable with respect to the image forming apparatus U1, and is raised when the manuscript Gi is manually placed on the platen glass PG by an operator. Is rotated to.

The image forming apparatus U1 has a UI (user interface) through which a user inputs and operates an operation command signal such as copy start. The IIT as a document reading device arranged below the transparent platen glass PG on the upper surface of the image forming apparatus U1 has an exposure optical system A. Reflected light from the document Gi that has passed the exposure position on the upper surface of the platen glass PG by the automatic document feeder U2 or a document manually placed on the platen glass PG is transmitted through the exposure optical system A to a CCD (solid-state imaging device). Element) R (red),
It is converted into G (green) and B (blue) electric signals.

IPS controlled by control C
The (image processing system) converts the RGB electric signals input from the CCD into image data of K (black), Y (yellow), M (magenta), and C (cyan), and temporarily stores them. The laser drive circuit D uses the image data as image data for forming a latent image at a predetermined timing.
Output to L. The laser drive circuit DL controlled by the control C outputs a laser drive signal to the ROS (latent image forming device) according to the input image data.

The image carrier PR is rotating in the direction of the arrow Ya, and the surface of the image carrier PR is then uniformly charged by the charger CC, and then at the latent image writing position Q1, the ROS (latent image forming device) is formed. Exposure scanning is performed by the laser beam L to form an electrostatic latent image. K to form a full-color image
Electrostatic latent images corresponding to four-color images of (black), Y (yellow), M (magenta), and C (cyan) are sequentially formed,
In the case of a monochrome image, only the electrostatic latent image corresponding to the K (black) image is formed.

The surface of the image carrier PR on which the electrostatic latent image is formed is rotationally moved and sequentially passes through the developing area Q2 and the primary transfer area Q3. The developing device G is a four-color developing device GK, GY of four colors K (black), Y (yellow), M (magenta), and C (cyan), which sequentially rotate in the developing area Q2 as the rotation axis Ga rotates. , GM, GC. The developing units GK, GY, GM, and GC of the respective colors have a developing roll GR that conveys the developer to the developing area Q2, and form an electrostatic latent image on the image carrier PR passing through the developing area Q2. Develop into a toner image. The cartridge mounting portions Hk, Hy, Hm, and Hc are provided in the developing containers of the developing devices GK, GY, GM, and GC.
Toners of respective colors are replenished from the toner replenishing cartridge mounted on.

Below the image carrier PR, an intermediate transfer belt B, a belt driving roll Rd, and a tension roll R are provided.
t, a walking roll Rw, an idler roll Rf, and a plurality of belt support rolls (Rd, Rt, Rw, Rf, T2a) including a backup roll T2a, a primary transfer roll T1, and a belt frame (not shown) that supports them. ) And have. Then, the intermediate transfer belt B
Is a belt support roll (Rd, Rt, Rw, Rf, T
It is rotatably supported in the direction of arrow Yb by 2a).

When forming a full-color image, the electrostatic latent image of the first color is formed at the latent image writing position Q1, and the toner image of the first color is formed in the developing area Q2. When the toner image passes through the primary transfer area Q3, the toner image is electrostatically transferred onto the intermediate transfer belt B by the primary transfer roll T1.
Next is transcribed. After that, in the same manner, the second color toner image, the third color toner image, and the fourth color toner image are sequentially transferred and primary-transferred onto the intermediate transfer belt B carrying the first color toner image, and finally the full-color multiplex is formed. A toner image is formed on the intermediate transfer belt B. When forming a monochromatic monocolor image, only one developing device is used, and the monochromatic toner image is primarily transferred onto the intermediate transfer belt B. Image carrier P after primary transfer
The residual toner on the R surface is discharged by the static eliminator JR and is cleaned by the image carrier cleaner CL1.

Below the backup roll T2a, a secondary transfer roll T2b is provided with the backup roll T2.
It is movably arranged between a position separated from 2a and a position in contact therewith. The backup roll T2a
The secondary transfer roll T2b constitutes a secondary transfer device T2. The backup rolls T2a and 2
The secondary transfer area Q4 depends on the contact area of the secondary transfer roll T2b.
Are formed. A secondary transfer voltage having a polarity opposite to the charging polarity of the toner used in the developing device G is supplied from the power supply circuit E to the secondary transfer roll T2b, and the power supply circuit E is controlled by the control C.

The sheet (transfer material) S stored in the sheet feeding tray TR1 or TR2 is taken out by the pickup roll Rp at a predetermined timing, and is separated by the separating roll Rs.
A plurality of transport rolls R separated in the sheet feeding path SH1
It is conveyed to the registration roll Rr by a. The sheet S conveyed to the registration roll Rr is aligned with the timing when the primary-transferred multiple toner image or the single-color toner image moves to the secondary transfer area Q4, and the pre-transfer sheet guide SG1.
From the secondary transfer area Q4. In the secondary transfer area Q4, the secondary transfer device T2 is connected to the intermediate transfer belt B.
The upper toner image is electrostatically secondarily transferred to the paper S. The residual toner on the intermediate transfer belt B after the secondary transfer is removed by the belt cleaner CL2.

Incidentally, the secondary transfer roll T2b and the belt cleaner CL2 are arranged so as to be capable of being separated from and contacted (separated and contacted) with the intermediate transfer belt B, and when the color image is formed, the final color is undetermined. The toner image is separated from the intermediate transfer belt B until it is primarily transferred to the intermediate transfer belt B. The secondary transfer roll cleaner CL3
Moves to and from the intermediate transfer belt B together with the secondary transfer roll T2b.

The sheet S on which the toner image is secondarily transferred is
After the transfer, the sheet is conveyed to the fixing area Q5 by the sheet guide SG2 and the sheet conveying belt BH. The fixing area Q5 is an area (nip) where the heating roll Fh and the pressure roll Fp of the fixing device F are in pressure contact with each other, and the sheet S passing through the fixing region Q5 is heated and fixed by the fixing device F. On the outer peripheral surface of the heating roll Fh, the oil for peeling the sheet is applied by the oil applying roll 21 on the upstream side in the rotation direction from the fixing region Q5. On the outer peripheral surface of the heating roll Fh, a cleaning device CL5 for cleaning the surface of the heating roll Fh is arranged downstream of the fixing area Q5 in the rotation direction.

In FIG. 1, a sheet discharge path SH2 is provided on the downstream side of the fixing area Q5 for fixing the toner image on the sheet S, and the sheet reverse path SH2 is provided in the sheet discharge path SH2.
3 is connected. A switching gate GT1 is provided at a branch point of the sheet discharging path SH2 and the sheet inverting path SH3. The sheet S conveyed to the sheet discharge path SH2
Is a sheet discharge roll Rh by a plurality of transport rolls Ra.
And is discharged to the discharge tray TR3 from the sheet discharge port Ka formed at the upper end of the image forming apparatus U1. The sheet inversion path SH3 is provided with a mylar gate GT2. The mylar gate GT2 is the switching gate G
The sheet S conveyed from the sheet reversing path SH3 from T1 is allowed to pass therethrough, and the sheet S that has once passed and then switched back is directed to the sheet circulation path SH4 side. The sheet S conveyed to the sheet circulation path SH4 is retransmitted to the transfer area Q4 through the sheet supply path SH1. The sheet conveying path SH is constituted by the elements indicated by the reference signs SH1 to SH4.

(Fixing Device and Cooling Device) FIG. 2 is a perspective view of the fixing device shown in FIG. FIG. 3 is a perspective view of the fixing device shown in FIG.
FIG. 4 is a sectional view taken along line IV-IV of FIG. FIG. 5 is a front view of the fixing device of FIG. 1 with a part of the case removed, showing a state in which the heating roll and the pressure roll are pressed against each other.

2 to 4, the fixing device F has a fixing case Fk, and the heating roll Fh is housed inside the fixing case Fk. The fixing case Fk
Is composed of upper and lower guide substrates 14F and 14R and an upper support plate T which will be described later. The heating roll (rotating member) Fh has a metal sleeve 1, a rubber elastic layer 2 and a releasable resin layer 3 formed on the outer periphery of the metal sleeve 1. A heater 4 is built in the heating roll Fh, and bearings 5F and 5R are attached to both front and rear ends (both ends of the X axis). The pressure roll (rotating member) Fp has a metal sleeve 6, a rubber elastic layer 7 and a releasable resin layer 8 formed on the outer periphery thereof. Bearings 10F and 10R are attached to both front and rear ends (both ends of the X-axis) of the pressure roll Fp.

2 to 4, the fixing device F has a horizontal base 11, and the front and rear end portions (X
Vertical substrates 12F and 12R are provided at both ends in the axial direction (see FIG. 2), respectively. The vertical guide boards 12F and 12R include the lower guide boards 13F and 13R and the upper guide board 1.
4F and 14R are respectively supported. The vertical boards 12F, 12R and the lower guide boards 13F, 13R
The lifting lever 1 is attached to the rotating shafts 15F and 15R supported by the
6F and 16R are rotatably supported at their right ends (Y ends), and cam followers 17F and 17R are rotatably supported at the free ends of the elevating levers 16F and 16R.

The lower guide boards 13F and 13R are
A pair of front and rear bearing support portions 13Fa and 13Ra are formed so as to open upward. A pair of front and rear bearing support portions 13
Fa and 13Ra are bearings 1 mounted on the pressure roll Fp.
0F and 10R are supported so as to be vertically movable, and the lower ends of the bearings 10F and 10R are supported by the lifting levers 16F and 16R. In the upper guide boards 14F and 14R,
A pair of front and rear bearing support portions 14Fa and 14Ra are opened downward and a lower end portion is formed narrow. Bearings 5F and 5R mounted on the heating roll Fh are supported by the pair of front and rear bearing support portions 14Fa and 14Ra so that the bearings 5F and 5R can move in the vertical direction and their downward movement can be restricted.

A camshaft 19 is rotatably supported on the vertical substrates 12F and 12R.
Cams 20F and 20R are fixed to the. An elevating motor unit M1 having a motor and a deceleration mechanism for elevating and lowering the pressure roll arranged on the rear side of the lower guide substrate 12R is supported by the vertical substrate 12R via a supporting member (not shown), and The output shaft is connected to the camshaft 19. Lifting motor unit M
The cam shaft 19 and the cams 20F and 20R are driven by one drive
Rotates, and the cam followers 17F and 17R move in the vertical direction.

In the state shown in FIG. 5 in which the cams 20F and 20R are rotated, the cam followers 17F and 17R and the elevating levers 16F and 16R are moved to the raised positions,
The pressure roll Fp has moved to a position where it comes into pressure contact with the heating roll Fh, and the heating roll Fh has moved to the upper end positions of the pair of front and rear bearing support parts 14Fa and 14Ra.
When the cams 20F and 20R rotate from the positions shown in FIGS. 4 and 5, the cam followers 17F and 17R descend. In that state, the pressure roll Fp descends, and the heating roll Fh also descends slightly to form a gap of about 1 mm between the pressure roll Fp and the heating roll Fh.

2 to 5, the vertical substrates 12F, 1
An oil coating roll 21 is rotatably supported on the 2R and the upper guide substrates 14F and 14R. The oil application roll 21 has a metal roll 22 having a large number of holes and an oil impregnation layer 23 on the outer peripheral surface thereof, and the oil impregnation layer 23 is covered with an oil supply amount control layer 24. The oil application roll 21 is in contact with the heating roll Fh, and the oil contained (filled) in the oil application roll 21 is heated via the oil application amount control layer 24.
It is designed to be applied to h.

3 to 5, the upper guide substrate 14 is shown.
A web supply roll 25, a web take-up roll 26, and a web support roll 27 are rotatably supported by F and 14R. The web take-up roll 26 is a lower guide substrate 14R.
The web winding motor unit M2 arranged on the rear side is driven to rotate. A web 29 for wiping off the oil on the surface of the heating roll Fh is wound around the web supply roll 25, and the web 29 is the web support roll 2
7 is wound around the web take-up roll 26 guided by 7 to clean the oil and the like remaining on the surface of the heating roll Fh. The cleaning device CL includes the web supply roll 25, the web winding roll 26, the web supporting roll 27, the web 29, and the web winding motor M2.
5 are configured.

2 to 5, the pre-fixing paper guide 3 is arranged on the vertical substrates 12F and 12R (see FIGS. 2 and 3) on the upstream side of the fixing region Q5 in the sheet conveying direction.
0, 31 and the sheet peeling member 3 on the downstream side of the fixing area Q5
2, 33 are fixedly supported.

3 and 5, a cooling fan (blowing fan) 35 is provided on the rear side surface of the vertical substrate 14R, and a non-sheet passing area cooling duct 36 is connected to the cooling fan 35. As the cooling fan 35, a centrifugal fan such as a sirocco fan can be used. The non-sheet passing area cooling duct 36 is provided for small size paper (maximum size paper A4L
This is a duct for cooling the non-sheet passing area which is a fixing area where the small size sheet does not pass when the paper (width narrower than EF (see FIG. 6)) continuously passes through the fixing area Q5. The non-sheet passing area cooling duct 36 includes an external duct 36a disposed outside the fixing device case Fk, an internal duct 36b disposed inside, and the internal duct 36b.
Has an elliptical (or elliptical) blower opening 36c formed on the lower surface of the inner end of the. The internal duct 36b is provided substantially parallel to one side above the heating roll Fh and has a substantially rectangular cross section.

FIG. 6 is a diagram illustrating a state in which cooling air is blown from the cooling fan to the heating roll of the fixing device through the duct for cooling the non-sheet passing area. In FIG. 6, the heater 4 is a heater having the same width as the width of A4LEF (A4 long edge feed, that is, A4 paper that conveys the long edge (longer edge) of the paper as the front end and the rear end in the conveyance direction). is there. That is, the heater 4 has the same width as the sheet passing area of the large size sheet (A4LEF) through which the large size sheet passes. As the maximum size paper, there are A4LEF and A3SEF (A3 short edge feed) papers. Further, as the small size paper having a width smaller than the maximum size paper, B4SEF, B5
LEF, A4SEF, B5SEF, etc., especially B5
SEF is the smallest size paper that is fixed. In FIG. 6, for example, when the minimum size sheet B5SEF is continuously fixed, the large size sheet fixing area W0 of the fixing area Q5 is fixed.
If the non-paper passing area W1b, which is the difference between the paper passing area W1a of the smallest size paper B5SEF and the non-paper passing area W1b, is not cooled by the cooling air, the temperature of the non-paper passing area W1b rises.

The temperature distribution of the non-sheet passing area W1b is generally high at the central portion and low at both ends. Therefore, the air outlet 36c has a substantially elliptical shape, and the air outlet 3
The opening area of 6c is set to be large at the central portion along the width direction of the paper S and small at both ends so that the opening area of the blower opening 36c corresponds to the temperature increase of the non-paper passing area W1b. In FIG. 6, the air outlet 36 is provided in a slit (not shown) provided at the lower end of the end wall of the duct 36 for cooling the non-sheet passing area.
An opening width adjusting plate 37 for adjusting the opening width of c is slidably supported. A rectangular hole 37a is provided on one side of the opening width adjusting plate 37, and a rack portion 37b having teeth of the same shape at equal intervals is provided on the side surface of the rectangular hole 37a. The shape of the end portion 37c of the area adjusting plate 37 is shown in FIG.
B, as shown in FIG. 7C, it has a shape similar to the end shape of the blower opening 36c.

2, 3 and 6, an upper support plate T is installed on the upper guide boards 14F and 14R, and an adjusting plate moving motor 39 is mounted on the upper surface of the upper support plate T. . Output shaft 3 of motor 39 for moving the adjusting plate
A pinion 40 is fixed to 9a. Pinion 40
Is arranged so as to mesh with the rack portion 37b of the opening width adjusting plate 37. When the pinion 40 is rotated by the drive of the adjusting plate moving motor 39, the opening width adjusting plate 37 reciprocates to adjust the opening area of the blower port 36c of the duct 36 for cooling the non-sheet passing area. An opening width adjusting device 41 is composed of the opening width adjusting plate 37, the adjusting plate moving motor 39, and the pinion 40. The cooling fan 35, the non-sheet passing area cooling duct 36, and the opening width adjusting device 41 constitute a cooling device 42 (see FIG. 6).

(Operation of Embodiment 1) FIG. 7 is a view for explaining the operation of the cooling device, and FIG. 7A shows the temperature distribution in the fixing region when the minimum size paper is continuously fixed without using the cooling device. FIG. 7B is an explanatory view of the opening width adjusting device of the cooling device, and FIG. 7C is a view showing a state in which the opening width adjusting plate is moved to a position where the blower opening is fully opened. FIG. 8 is a diagram for explaining the temperature distribution of the heating roll of the first embodiment. The solid line in FIG. 8 is the temperature distribution when the maximum size sheet is continuously fixed, and the dotted line is the cooling device of the first embodiment. However, it is a diagram showing a temperature distribution when a minimum size sheet is continuously fixed. If the paper S is a maximum size paper such as A4LEF paper, the paper S
Is moved through the fixing area Q5, the adjusting plate moving motor 3
The toner image on the paper S is fixed without driving the cooling fan 9 and the cooling fan 35. In this case, the temperature distribution on the surface portion of the heating roll Fh is as shown by the solid line in FIG.

In FIG. 7A, the smallest size paper B5S
When the EF is continuously fixed, the paper is passed only through the paper passing area W1a and is not passed through the non-paper passing area W1b. In this case, if the cooling air is not blown from the air outlet 36c of the duct 36 for cooling the non-sheet passing area, the temperature of the non-sheet passing area W1b will be much higher than the temperature of the sheet passing area W1a. Therefore, in the first embodiment, in order to prevent the temperature rise of the non-sheet passing area W1b, the cooling air is blown from the blower port 36c of the duct 36 for cooling the non-sheet passing area. In that case, the adjustment plate moving motor 39 shown in FIG. 7B is driven to rotate the pinion 40, and the end portion 37c of the area adjustment plate 37 is moved to the B5SEF position of the blower port 36c (see FIG. 7C) to cool the cooling fan. 35 (see FIG. 6) is rotated. At this time, the cooling air from the cooling fan 35 passes through the non-sheet passing area cooling duct 36, and from the fully opened air blowing port 36c to the heating roller F passing through the non-sheet passing area W1b.
The air is blown to the surface part of h.

The cooling air blown from the blower port 36c is blown at a blowing amount corresponding to the temperature rise of the non-sheet passing area W1b during rotation. That is, a large amount of cooling air is blown to the high temperature central portion of the non-paper passing area passing surface from the central portion having a large area of the blower opening 36c, and is supplied to both ends of the non-paper passing area passing surface having a relatively low temperature. Can blow a relatively small amount of cooling air from both ends of the air outlet 36c having a small area.
In this case, the temperature distribution of the non-sheet passing area W1b when the minimum size paper is continuously fixed is as shown by the dotted line in FIG.
Compared with the temperature distribution of the maximum size width sheet shown by the solid line in FIG. 8, the temperature rise in the non-sheet passing area W1b is suppressed within the allowable range of 20 to 30 ° C.

Paper size for continuous fixing is A4SEF, B
In the case of 5 LEF, the area adjusting plate 37 is moved to a position corresponding to the sheet size shown in FIG. 7C, the opening area of the blower opening 36c is adjusted, and cooling air is blown.

The cooling fan 35 provided on the vertical substrate 12R of the fixing device F passes through the non-sheet passing area W1b of the heating roll Fh from the air outlet 36c of the duct 36 for cooling the non-sheet passing area having a small cross-section. The cooling air can be sent only to the surface part (high temperature part) to be cooled. Therefore, since the air is not blown to an extra place, the small cooling fan 35 can effectively prevent the temperature rise of the non-sheet passing area W1b. Therefore, although the fixing device F has a compact and simple structure, even when the sheets S having different size widths are continuously fixed, the non-sheet passing area passing surface of the heating roll Fh is cooled substantially uniformly, and the sheet is not passed. It is possible to prevent the temperature of the paper area W1b from rising and prevent the temperature of the boundary portion of the paper passing area W1a from the non-paper passing area W1b from decreasing. Therefore, the fixing failure does not occur on the paper S.

(Embodiment 2) In Embodiment 1, a dedicated cooling fan 35 for cooling the sheet passing area of the fixing device is provided.
By omitting the dedicated cooling fan 35, it is possible to utilize the blowing capacity of the exhaust device that exhausts the air inside the image forming apparatus. FIG. 9 is an explanatory view of the second embodiment of the fixing device of the present invention, and is a view showing a state in which all the air exhausted from the exhaust device for exhausting the air inside the image forming device is exhausted to the outside of the image forming device. is there. FIG. 10 is a diagram showing a state in which part of the air exhausted from the exhaust device that exhausts the air inside the image forming apparatus is used to cool the non-sheet passing area of the fixing device. In the description of the second embodiment, constituent elements corresponding to those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. This Example 2
Is different from Example 1 in the following points, but is configured similarly to Example 1 in other points.

Rear portion of the image forming apparatus U1 (-X side portion)
Is provided with an exhaust device exhaust device 51 for exhausting the air inside the image forming apparatus U1, and the exhaust device 51 is provided with an exhaust fan 52. A duct 53 for cooling the non-sheet passing area is connected to the exhaust device 51. The duct 53 for cooling the non-sheet passing area is an external duct 53a arranged outside the fixing device case Fk and an inside arranged inside the fixing device case Fk. Duct 53
b and an elliptical (elliptical) blower port 53c formed on the lower surface of the inner end portion of the internal duct 53b. The internal duct 53b is provided substantially parallel to one side above the heating roll Fh and has a substantially rectangular cross section. Exhaust fan 5
A shutter 56 is vertically movably supported on the lower side of the rear surface of the second surface 2. The shutter 56 is vertically moved by a shutter vertical movement motor (not shown) to block a part of exhaust gas. An air flow rate adjusting plate 57 is vertically movable outside the fixing device F in the non-sheet passing area cooling duct 53. The air flow rate adjusting plate 57 is moved up and down by an air flow rate adjusting plate vertical movement motor (not shown) to adjust the air flow rate. It is supposed to do.
Cooling for cooling the non-sheet passing area from the exhaust device 51 having the exhaust fan 52, the duct 53 for cooling the non-sheet passing area, the shutter 56, the air volume adjusting plate 57, the motor for vertically moving the shutter, the motor for vertically moving the air volume adjusting plate, and the like. The device 59 is configured.

(Operation of Second Embodiment) In the second embodiment of the fixing device of the present invention having the above-described structure, the maximum size sheet A4LE is used.
When F is continuously fixed, the shutter 56 is opened and the air volume adjusting plate 57 is closed, as shown in FIG. Small size paper other than maximum size paper A4LEF (B5LEF, A
In the case of continuously fixing (4SEF, B5SEF, etc.), as shown in FIG. 10, the shutter 56 is closed and the air volume adjusting plate 57 is opened more as the size of the paper passing through the paper passage area is smaller. By utilizing the exhaust air from the exhaust device 51, it is not necessary to provide a dedicated cooling fan for cooling the non-sheet passing area of the fixing device F, so that the space and cost required for the cooling device for the fixing device can be suppressed. You can

(Modifications) The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-mentioned embodiments, and is within the scope of the gist of the present invention described in the claims. Thus, various changes can be made. A modified embodiment of the present invention is illustrated below. (H01) In the first and second embodiments, the opening areas of the air outlets 36c and 53c of the non-paper passing area cooling ducts 36 and 53 correspond to the temperature increase of the non-paper passing area W1b of the heating roll Fh. Then, the amount of air blown from the air blow ports 36c, 53c to the non-paper passing area passing surface of the heating roll Fh is adjusted.
Instead of this, the non-paper-passing area R2 of the heating roll Fh and the blower ports 36 of the non-paper-passing area cooling ducts 36 and 53 are corresponding to the increase in temperature of the surface of the non-paper-passing area of the heating roll Fh.
It is also possible to adjust the distance between c and 53c. (H02) In the first embodiment, when the small size paper S passes through the fixing area Q5, the non-paper passing area of the heating roll Fh is cooled. However, the number of the small size paper S passed is counted. A cooling counter and a timer for counting the time from the start of copying are provided to operate the cooling fan 35 when a predetermined number of small-size paper S are continuously fixed or when the small-size paper S is fixed for a predetermined time. It is also possible to configure so that it is made to. (H03) In the second embodiment, the case where the exhaust device 51 of the image forming apparatus U1 is used has been described, but it is also possible to use another blower provided inside the image forming apparatus U1. (H04) In the second embodiment, the non-sheet passing area cooling duct 53
It is also possible to provide a louver at the air blowing port 53c to adjust the direction of the cooling air and blow the air to the non-sheet passing area passing surface of the heating roll Fh. (H05) The present invention relates to a heating roll Fh and a pressure roll F.
Not only the fixing device F having p, but also the fixing device F having a heating roll and a pressure belt can be applied. (H06) The present invention is not limited to the one-sided reference fixing device F in which one side of the sheet S is aligned with the reference line BL of the heating roll Fh and the widthwise center of the sheet S is set to the axial centerline of the heating roll Fh. It is also applicable to the central reference fixing device F that conveys lines together.

[0053]

The fixing device of the present invention described above can achieve the following effects (E01) to (E03). (E01) It is possible to efficiently prevent the temperature rise in the non-sheet passing area of the fixing rotary member including the heating rotary member and the pressurizing rotary member of the fixing device. (E02) It is possible to reduce variations in temperature in the non-sheet passing area. (E03) It is possible to prevent the temperature from decreasing near the boundary between the non-paper passing area and the paper passing area.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an image forming apparatus including a fixing device according to a first exemplary embodiment of the present invention.

FIG. 2 is a perspective view of the fixing device shown in FIG. 1 as viewed obliquely from the front.

FIG. 3 is a perspective view of the fixing device shown in FIG. 1 as viewed obliquely from behind.

4 is a sectional view taken along line IV-IV of FIG.

5 is a front view of the fixing device of FIG. 1 with a part of the case removed, showing a state in which a heating roll and a pressure roll are in pressure contact with each other.

FIG. 6 is a diagram illustrating a state in which cooling air is blown from a cooling fan to a heating roll of the fixing device through a duct for cooling the non-sheet passing area.

FIG. 7 is a diagram for explaining the operation of the cooling device, and FIG. 7A is a diagram showing a temperature distribution in a fixing region when a minimum size sheet is continuously fixed without using the cooling device.
FIG. 7 is an explanatory view of an opening width adjusting device of the cooling device, and FIG. 7C is a view showing a state in which the opening width adjusting plate is moved to a position where the air outlet is fully opened.

FIG. 8 is a diagram illustrating a temperature distribution of the heating roll.

FIG. 9 is a cross-sectional view of a cooling device according to a second exemplary embodiment of the fixing device of the present invention, and is a diagram for explaining a state in which all the exhaust air from the exhaust fan is exhausted outside the device.

FIG. 10 is a diagram showing a state in which a part of the exhaust air from the exhaust fan is blown as cooling air from a ventilation port to a non-paper passing area of a heating roll through a non-paper passing area cooling duct. .

FIG. 11 is a cross-sectional view of a conventional heating roll and pressure roll.

FIG. 12 is a diagram illustrating a relationship between a heating roll and a pressure roll and a paper size when viewed from the XII direction in FIG. 11.

FIG. 13 is a diagram illustrating a temperature distribution of the heating roll of FIG. 11.

[Explanation of symbols]

F ... Fixing device, Fh ... Heating rotating member (rotating member), Fk
... fixing device case, Fp ... pressure rotating member (rotating member), Q5 ... fixing area, S ... transfer material, W1a ... paper passing area,
W1b ... Paper non-passage area, 35, 52 ... Blower fan, 36, 5
3 ... Non-sheet passing area cooling duct, 36a, 53a ... External duct, 36b, 53b ... Internal duct, 36c, 53c ... Blower, 41 ... Opening width adjusting device, 42, 59 ... Cooling device,
51 ... Exhaust device.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigehiko Hasenami             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             X Co., Ltd. F term (reference) 2H027 DA12 DC10 JA11 JB12 JB13                       JB15 JB27 JC08                 2H033 AA03 BA02 BA29 CA09 CA30                       CA53

Claims (3)

[Claims] 1. A fixing device comprising the following constituent features (A01) to (A05): (A01) A heating rotary member and a pressurizing member that form a fixing region by a pressure contact region that presses while rotating with each other. A heating member and a pressure rotating member, which are rotating members and heat-fix the unfixed toner image when the transfer material on which the unfixed toner image is formed passes through the fixing area; A case for a fixing device that accommodates a member inside; (A03) The small size transfer material, in which the size in the width direction of the fixing area is smaller than the maximum size transfer material, when the small size transfer material passes through the fixing area. Is a fixing area through which a sheet passes, and a fixing area other than the sheet passing area is defined as a non-sheet passing area, and a non-sheet passing area passing surface that is a surface portion of the heating rotary member that passes through the non-sheet passing area. In order to cool A cooling device having a non-sheet passing area cooling duct in which a blower port is formed facing the non-sheet passing area passing surface of the rotating member, and a blower fan that blows cooling air to the non-sheet passing area cooling duct, (A04) The non-sheet passing area cooling duct having an internal duct arranged inside the fixing device case and an external duct connected to the internal duct and arranged outside the fixing device case, A05) The blower fan, which is arranged outside the fixing device case and blows cooling air to the external duct. 2. The fixing device according to claim 1, further comprising the following constituent features (A06): (A06) The opening area is large in the central portion along the width direction and both ends in the axial direction. The blower outlet set to a small size. 3. The fixing device according to claim 1, wherein the fixing device has the following constituent features (A07), and (A07) a non-sheet passing area according to the width of the transfer material passing through the fixing region. An opening width adjusting device that adjusts the length of the opening in the width direction so that the cooling air is blown only to the non-sheet passing area passing surface which is the surface portion of the rotating member passing through.