JP3132191B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing a toner image adhered to a sheet on an electrophotographic recording apparatus such as a laser printer.

[0002]

2. Description of the Related Art A fixing device in an electrophotographic recording apparatus such as a laser printer has a configuration in which a toner image is fused and fixed to a sheet by passing the sheet on which the toner image is adhered. As a means for fusing the toner image, there are a xenon flash method using radiant heat transfer, a planar heater method using convective heat transfer, and the like.
Since the working temperature is relatively low at about 120 to 180 [deg.] C., which is excellent in safety, and has a paper conveying function, a heating roller method is often used.

On the other hand, as a trend of printers in recent years, in addition to conventional black printing and multicolor printing, demand for a multicolor printer capable of printing very many colors has been increasing. The types of paper that can be used have been expanded to include PPC paper, bond paper, postcards, envelopes, OHP sheets, label paper, and the like.

A fixing device of a heat roller type in such an electrophotographic recording apparatus uses a heating roller in which Teflon is coated on a core metal or a silicon rubber layer is provided, and a silicon rubber layer is provided on the core metal. In many cases, a pressure roller provided with such as is used. Particularly, in an electrophotographic recording apparatus such as a color printer, a heating roller provided with a silicone rubber layer is used to prevent an offset phenomenon and to improve the light transmittance of OHP paper, and a surface of the heating roller is used to prevent the offset phenomenon. In many cases, silicone oil is applied to the surface. In many cases, the silicone oil is applied by bringing a felt impregnated with the oil into contact with a heating roller, or by applying a porous roller having oil therein to the heating roller. Further, an oil blade is brought into contact with the heating roller in order to make the amount of oil applied to the surface of the heating roller uniform and appropriate.

In any of the fixing devices of the oil application type, the oil application felt or the roller and the oil blade are attached to an oil tray and brought into contact with a heating roller, and apply the oil in the oil tray to the heating roller to remove excess oil. Has been proposed to collect oil in an oil tray, and it is necessary to replace oil-applied felts or rollers and supply oil.

Incidentally, this type of fixing device is disclosed in
No. 282 and JP-A-63-139381.

[0007]

However, these conventional fixing devices can easily perform maintenance work such as replacement of oil-applied felts or rollers and replenishment of oil without enlarging the entire structure of a small electrophotographic recording device. Lack of attention to

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to make a component for applying oil to a heating roller and regulating the amount of oil to be a unit having a small size and excellent in maintenance workability, and to apply an oil without increasing the size of an electrophotographic recording apparatus. An object of the present invention is to provide a fixing device capable of easily performing maintenance operations such as replacement of felts or rollers and replenishment of oil.

[0009]

SUMMARY OF THE INVENTION The present invention provides a heating roller and a heating roller.
The pressure rollers are arranged side by side in the horizontal direction.
Under the side so that it can be inserted and removed from the side, and
A dent is formed at the rear end, and felt is laid at the bottom of the dent.
Packed, limited oil in free state in dents
At the same time, make the oil supply bottle detachable on the dent,
The oil supply bottle is mounted on the recess and the oil supply bottle
The oil supply port opens with the supply port of
Oil supplied into the dent from the inlet of the tor
Supply to heating roller via felt by capillary action
Is the fact characterized by, or heat roller and Ka圧Ro
Rollers are arranged side by side in the horizontal direction, and the oil tray is below the heating roller.
At the rear end
A dent is formed in the bottom of the dent and the dent and another bottom.
Spread felt on each bottom of the oil pan
The oil in the free state is limited only in the
Oil supply bottle is detachable on the dent, and oil supply
The bottle is mounted on the recess and the supply port of the oil supply bottle
Is open with the oil supply bottle facing the dent.
The oil supplied into the recess from the supply port and the oil regulating member
The oil collected in the oil tray and the dent and the dent
Felt from each of the other bottoms by capillary action
And supplied to the heating roller via the heating roller .

[0010]

[Operation] Oil for preventing offset in the recess at the rear end of the oil tray is applied to the surface of the heating roller by an oil application member, and excess oil on the surface of the heating roller is scraped off by the oil regulating member to be placed in the oil tray. It is collected and returns to the dent or oil application member. When the oil in the depression decreases, new oil is supplied from an oil supply bottle installed on the depression.

The heating roller and the pressure roller arranged side by side in the horizontal direction are convenient for a fixing device in a small electrophotographic recording apparatus which discharges a sheet fixed on a sheet discharge tray formed on an upper surface of the apparatus main body. In addition, by installing the oil tray below the heating roller so as to be inserted and removed from the lateral direction, maintenance workability can be improved without increasing the size of the apparatus.

[0012]

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

FIG. 2 is a vertical sectional side view of the color laser printer according to the present invention. The photosensitive belt 1 is rotatably stretched around stationary rotating rollers 2 to 4 and a tension roller 5, and is uniformly charged by a charger 6 while being rotated at a constant speed, and according to an image signal of each color. Exposure device 7
The electrostatic latent images corresponding to the respective colors are sequentially formed by being exposed by the laser beam 7a emitted from the
The electrostatic latent images are sequentially developed by a developing device using a developer of one corresponding color to form a toner image for each color. The toner images of the respective colors on the surface of the photosensitive belt 1 are superimposedly transferred onto the surface of the transfer drum 12 that rotates synchronously while being in contact with the surface of the photosensitive belt 1, and become a color toner image on the surface of the transfer drum 12.

Sheets 14 stored in sheet cassette 13
Are extracted by the paper feed roller 15 and conveyed while preventing double feed in cooperation with the separating member 16 to be transferred to the registration roller 1.
7, the paper is sent to the transfer device 18 after the paper is adjusted and the transfer timing of the color toner image on the surface of the transfer drum 12 is adjusted and controlled. The transfer device 18 applies a mechanical pressing force and a transfer electric field from the back surface of the fed paper 14 to the transfer drum 12 while contacting the paper 14, thereby transferring the color toner image on the surface of the transfer drum 12 to the paper 14. Transcribe. Paper 14 onto which color toner image has been transferred
The color toner image is thermally fixed on the surface of the sheet 14 while passing between the heating roller 19 and the pressure roller 20 of the fixing device. The paper 14 on which the color toner image is thermally fixed is
The sheet is discharged onto a sheet discharge tray 22 via a sheet discharge roller 21.

A belt cleaner 23 cleans the toner remaining on the surface of the photosensitive belt 1, and a drum cleaner 24 cleans the toner remaining on the surface of the transfer drum 12. In addition,
The drum cleaner 24 is raised so that the cleaning action does not work in the process of forming a color toner image on the surface of the transfer drum 12, and is pressed so as to act on the surface of the transfer drum 12 after transferring the color toner image onto the paper 14. .

Next, referring to FIG. 1 and FIGS.
The details of the fixing device according to the present invention will be described.

The fixing device melts the unfixed toner image and fixes (fixes) the toner image on the surface of the sheet 14 so that the sheet 14 on which the toner (color toner) image is adhered is heated by the heating roller 1.
9 and the pressure roller 20 for heating. The heating roller 19 has a surface layer 19b formed by coating a surface of an aluminum cylindrical metal roller 19a with Teflon or molding silicone rubber.
Therefore, in a general small color laser printer (printing capacity of about 8 to 10 sheets / minute on A4 size paper), 120
Heat to a surface temperature of about 200 ° C. Further, the cleaning pad 25 a of the heating roller cleaner 25 is pressed against the surface of the heating roller 19.

The pressure roller 20 has a structure in which a core layer 20a is provided with a surface layer 20b formed by molding silicone rubber. In a general small color laser printer as described above, the nip width is about 2 to 5 mm. Heating roller 1
9 is pressed. The pressure roller 20 is used for the heating roller 1.
Although the heater 20c is provided inside similarly to 9, the heater 20c may be omitted. The pressure roller 20 is driven by the rotation of the heating roller 19 by the frictional force generated by the pressure contact with the heating roller 19, or
Are driven by gears.

In this embodiment, a fixing device is installed in the upper part of the printer in order to reduce the size of the printer, and the heating roller 19 and the pressure roller 20 of the fixing device are substantially horizontally opposed to each other. It is arranged.

In such a fixing device, when the sheet 14 is heated and fixed on the sheet 14 by passing the sheet 14 between the heating roller 19 and the pressure roller 20, a part of the melted toner is This causes a so-called offset phenomenon to adhere to the surface. If the amount of the offset toner is large, there arises a problem that the life of the cleaning pad 25a is shortened, and the cleaning pad 25a is re-adhered to the sheet 14 without being cleaned, thereby significantly deteriorating the image quality.

In order to reduce the offset phenomenon, it is important to enhance the releasability of the heating roller 19 and the toner. For example, dimethyl silicone oil which is excellent in safety, heat resistance and releasability is used as a release agent. It is applied to the surface of the heating roller 19. The specifications of the oil-applied felt 26 and the oil blade 27 are set so that the amount of applied oil is about several mg to several tens of mg per A4 size sheet. It is difficult to completely prevent the phenomenon, and if used for a long time, the cleaning pad 25a, the oil-applied felt 26, and the oil blade 27 become stained by the offset toner, and maintenance work such as replacement and cleaning is required.

The fixing device according to the present invention includes a heating roller 19.
The oil supply mechanism for the surface and the maintenance workability are taken into consideration, and the oil supply mechanism will be described below.

The heat-resistant oil-applied felt 26 is held at one end of a mounting base 29 which is fixed to the bottom of an oil tray 28 made of metal or heat-resistant resin or the like via a thin plate spring 30. You. The intermediate portion of the oil-applied felt 26 is folded back so as to sandwich the thin leaf spring 30 and is pressed against the surface of the heating roller 19 with a force of about several N by the elasticity of the thin leaf spring 30. After the other end is similarly spread on the oil tray 28, the end thereof is recessed at the rear end of the oil tray 28a.
The oil is sucked up by capillary action and applied to the contact surface with the heating roller 19.
The oil application using only the oil application felt 26 has poor stability of the application amount, and the texture of the felt surface may be remarkably generated on the paper as an oil streak. The oil blade 2 for equalizing the oil application amount
7 is a thin plate spring made of heat-resistant rubber such as fluororubber or the like
1 is formed or adhered on the oil tray 28.
By fixing the thin plate spring 31 to the base 29 in the inside, the thin plate spring 31 is pressed against the surface of the heating roller 19 by the elasticity of the thin plate spring 31. The oil blade 27 for the heating roller 19
The contact at the tip is θ = 0 with respect to the tangent to the heating roller 19.
It is desirable to make contact at an angle of about 30 °, and the amount of oil applied to the surface of the heating roller 19 is changed by changing the contact pressure.

However, it is difficult to accurately manufacture the straightness of the tip of the oil blade 27, and the amount of deflection of the tip of the oil blade 27 is limited to 0.5 in order to regulate the amount of oil applied.
The heating roller 1 must be kept in contact with the heating roller 1 while maintaining the contact pressure at about 1 mm.
In order to attain about Kgf), it is necessary to make the length of the oil blade 27 20 mm or more, which is a great obstacle to downsizing the device.

In this embodiment, attention is paid to the fact that the elastic modulus of fluororubber is significantly smaller than the elastic modulus of phosphor bronze, and as shown in FIG. By setting the dimension L1 so as to be smaller than the elastic modulus of the entire regulating member, that is, the dimension L2, the dimension L2 can be made smaller than that of the conventional device. As an example, when the thickness of the fluoro rubber oil blade 27 is 3 mm, the width is 230 mm, and the thickness of the phosphor bronze thin leaf spring 31 is 0.4 mm, the dimension L
By setting 1 to about 1 mm to about 3 mm of the conventional apparatus, the dimension L2 can be reduced from 20 mm or more to half of the conventional L2.

The oil applying mechanism and the oil amount regulating mechanism, which have been miniaturized by the above-described measures, are combined into one oil tray 28 to form the oil supply unit 32 and are arranged below the heating roller 19. And the oil blade 27
All the excess oil and the like scraped off by the oil collecting device can be recovered in the oil tray 28, and can be reused so as to be sucked up by the oil application felt 26 and applied to the heating roller 19 again. It is a target.

The oil supply unit 32 is configured to be detachable from the fixing device in the direction of the arrow.

As shown in FIG. 4, the oil supply unit 32 is configured such that an oil supply unit fixing spring 34 of the fixing device main body frame 33 is engaged with oil tray fixing projections 28b provided on both side walls of the oil tray 28. Installed in the fixing device.
In this installation state, the pressing force of the oil supply unit fixing spring 34 that engages with the oil tray fixing projection 28b generates a component force in the direction in which the oil tray 28 is pulled into the pressing surface, and the component force causes the oil tray 28 to move. Acts to pull in. The oil tray 28 drawn in by this component force has a configuration in which the positioning guide 28 d provided on the oil tray 28 abuts against the outer peripheral surface 35 a of the bearing 35 of the heating roller 19 to accurately position the oil tray 28 with respect to the heating roller 19. Yes,
In this state, the specifications of the components are set so that the contact pressure of the oil application felt 26 (not shown) and the contact position, contact angle, and contact pressure of the oil blade 27 (not shown) with the heating roller 19 become desired values.

In order to pull out the oil supply unit 32 for maintenance, the handle 2 is attached to the rear wall of the oil tray 28.
8c are provided. In this embodiment, the oil tray 28
The front wall is inclined and a rib 28e is provided on a part of the front wall to function as a sheet transport guide.

Next, oil supply in the oil supply unit 32 will be described.

The amount of oil applied to the heating roller 19 is
If the amount is too small, the effect as an anti-offset agent decreases,
If too much, oil adheres to the paper. The appropriate amount of oil to be applied in the process of fixing one sheet depends on the surface condition of the heating roller 19 and the type of toner, but is about 10 to 15 mg per A4 size sheet. Under these conditions, the amount of oil necessary for fixing for the life of the fixing device (30 k sheets / A4 size) is calculated as: 0.015 g × 30000 sheets × 0.97 ≒ 437 cc (however, the oil specific gravity is set to 0.95 g). 97), and an amount of 500 cc or more is required in consideration of the loss of volatile components and the like. A large amount of space is required to hold the required amount of oil in the fixing device from the beginning, and the oil supply structure is complicated, and the structure is against the downsizing of the printer body, cost reduction, and improvement of user maintenance. Become.

Therefore, in this embodiment, a small-capacity oil supply bottle 36 that can be replaced in accordance with the replacement cycle of the cleaning pad 25a is detachably mounted on the oil tray 28 described above. With such a configuration, when the user replaces the cleaning pad 25a, the oil supply bottle 36 can also be replaced, and the burden on the user can be reduced. The life of the cleaning pad 25a is about 3K sheets in consideration of various conditions, and the corresponding oil consumption is about 50 cc according to the above calculation.

As shown in FIGS. 1 and 5, an oil supply bottle 36 made of polypropylene or the like is moved along an oil tray 28f along a bottle guide 28f provided at the rear of the oil tray 28.
The two hollow needles 28g installed and raised at the bottom of the recess 28a in the oil tray 28 are attached to the rubber film 36a provided at the bottom of the oil supply bottle 36 by the mounting. Pierce the oil supply bottle 3
6 to form two communication holes, and send air from one of the hollow needles 28g into the oil supply bottle 36,
The oil in the oil supply bottle 36 is leaked from the other side and supplied to the recess 28a of the oil tray 28.

The oil in the recess 28a is sucked up by the capillary phenomenon of the oil-applied felt 26 and
The liquid surface is consumed by being applied to the lower surface 9 and the liquid level is lowered.
The hole of the hollow needle 28g opens in the recess 28a,
When the amount of oil in a decreases, the oil supply bottle 36
The oil is leaked by sending air into the inside, and a constant amount of oil is always accumulated in the recess 28a.

When the oil supply bottle 36 is taken out of the oil tray 28, the hollow needle 28g comes out of the rubber film 36a. However, since the hole of the rubber film 36a is closed due to the elasticity of the rubber, the oil remains inside the oil supply bottle 36. Even if the oil supply bottle 36 is taken out of the oil tray 28 in a state in which the oil is supplied, there is no fear that the oil flows out.

Further, the oil tray 2 is used for maintenance work or the like.
8 is removed from the fixing device main body and the amount of oil in the oil tray 28 in the free state is reduced by the depression 28a.
Since the oil-applied felt 26 is laid on the other bottom surface of the oil tray 28 in a very small amount in an area where the oil-applied felt 26 does not exist, the oil is immediately discharged from the oil tray 28. There is little worry about spills.

Next, the heating roller cleaner 25 in this embodiment will be described with reference to FIG. Even if oil is applied to the heating roller 19, the offset phenomenon cannot be completely eliminated, and the toner slightly adheres to the surface of the heating roller 19 depending on conditions. In order to remove the adhered toner, it is necessary to perform cleaning in a region between the time after fixing and the time when oil is applied.

The cleaning pad 25a is made of heat-resistant felt and has a back surface adhered to the pad case 25b.
f) It is pressed against the heating roller 19 with a pressing force of approximately. In order to attach / detach the cleaning pad 25a, it is necessary to release the pressing by the pad pressing spring 37. For that purpose, a new releasing mechanism needs to be added, which causes an increase in cost. Therefore, in this embodiment, the paper ejection guide 38 is rotatably installed in consideration of the jam processing in the fixing device, and the paper ejection guide 38 is rotated to a position indicated by a one-dot chain line to rotate the paper ejection guide 38. By opening the cleaning pad 25a, the cleaning pad 25a can be attached and detached in the direction of the arrow using the space. The positioning of the cleaning pad 25a is performed by the body frame 33 and the end 38a of the paper discharge guide 38. Thus, the cleaning pad 25a can be replaced without adding a special release mechanism.

In order to control the temperature of the heating roller 19, a non-contact type temperature detector (for example, a thermistor) 39 which does not damage the surface of the heating roller 19 is installed.
The temperature detector 39 is located in the space between the oil application felt 26 and the cleaning pad 25a and is supported by the main body frame 33, so that accurate temperature detection can be stably performed without being affected by the flow of the surrounding air. It can be realized.

[0040]

As described above, according to the present invention, an oil applying mechanism and an oil applying mechanism are provided below the heating roller in a fixing device in which a heating roller and a pressure roller are juxtaposed in a horizontal direction suitable for a small electrophotographic recording apparatus. By installing an oil supply unit including an oil tray with a built-in amount regulating mechanism detachably from the lateral direction, the handleability of the oil supply unit could be improved.

Further, by disposing the oil tray below the heating roller, it is possible to easily apply oil to the surface of the heating roller and to collect excess oil using the same oil tray. And wasteful oil consumption can be eliminated.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a fixing device according to the present invention.

FIG. 2 is a longitudinal sectional view of a color laser printer using the fixing device according to the present invention.

FIG. 3 is a perspective view of an oil blade in the fixing device according to the present invention.

FIG. 4 is a perspective view illustrating an installation state of an oil supply unit in the fixing device according to the present invention.

FIG. 5 is a perspective view showing an installed state of an oil supply bottle according to the present invention.

[Explanation of symbols]

19: heating roller, 20: pressure roller, 25a: cleaning pad, 26: oil-applied felt, 27: oil blade, 28: oil dish, 28a: dent, 28g ...
Hollow needle, 32 ... Oil supply unit, 36 ... Oil supply bottle.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Katsuyoshi Onose 1-1-1, Higashitaga-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Information and Video Media Division (56) References A) JP-A-57-182768 (JP, A) JP-A-2-236578 (JP, A) JP-A-59-147166 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) G03G 15/20

Claims (2)

(57) [Claims] 1. A heating roller and a pressure roller installed in a pressure-contact state, an oil application member for applying oil for preventing offset to the heating roller, and an oil for regulating an amount of oil applied to the heating roller. A fixing member that includes a regulating member, an oil tray that receives the oil application member and an oil application amount regulation, and that passes the sheet with the toner image attached between the two rollers to fix the toner image on the sheet. The heating roller and the pressure roller are arranged side by side in the horizontal direction, the oil tray is installed below the heating roller so as to be insertable and removable from the lateral direction, and a recess is formed at a rear end thereof, and the bottom of the recess is formed. The oil in the free state is limited in the dent, and an oil supply bottle is made detachable on the dent, and the oil supply bottle is It mounted above an opening in a state in which the supply port of the oil supply bottle is opposed to the recess above,
A fixing device, wherein oil supplied from the supply port of the oil supply bottle into the depression is supplied from the depression to the heating roller via the felt by a capillary phenomenon. 2. A heating roller and a pressure roller installed in a press-contact state, an oil applying member for applying oil for preventing offset to the heating roller, and an oil for regulating an amount of oil applied to the heating roller. A fixing member that includes a regulating member, an oil tray that receives the oil application member and an oil application amount regulation, and that passes the sheet with the toner image attached between the two rollers to fix the toner image on the sheet. The heating roller and the pressure roller are arranged side by side in the horizontal direction, the oil tray is installed below the heating roller so as to be insertable and removable from the lateral direction, and a recess is formed at a rear end thereof, and the bottom of the recess is formed. And a felt is spread on each of the bottoms of the oil tray, which is the bottom of the recess, so that the oil that is free in the recess is limited, and an oil supply bottle is placed on the recess. The oil supply bottle is mounted on the recess, the supply port of the oil supply bottle is opened in a state facing the recess, and the oil supply bottle is supplied into the recess from the supply port of the oil supply bottle. And the oil collected by the oil regulating member into the oil tray are supplied from the dent and the other bottom of the dent to the heating roller via the felt by capillary action. Fixing device.