JPH06186794A - Process cartridge and image forming device - Google Patents

Abstract

PURPOSE:To suppress the deformation of a process cartridge frame body caused by heat. CONSTITUTION:In the process cartridge capable of being attached/detached to/from an image forming device main body, a frame body, an image carrier 1, a process means acting on the image carrier 1, a heat insulating layer A provided on the frame body located on the side of a fixing means 5 provided on the side of the image forming device main body, when the process cartridge is fitted to the image forming device main body are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process cartridge and an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic apparatus or a laser beam printer, an image carrier such as a photoconductor or a dielectric, a charging means for charging the image carrier, and the image carrier. A cartridge in which a developing means for visualizing the electrostatic latent image formed above is incorporated in one unit is well known.

[0003]

However, the cartridge has the following problems when the fixing means is arranged very close to the cartridge in order to realize the miniaturization of the apparatus.

That is, the fixing means is usually temperature-controlled to maintain 180 ° C. in order to maintain the fixing property of an image during operation, but depending on the environment, the temperature is 10 ° C. to 20 ° C. It may be maintained at an elevated temperature. When recording is continuously performed under such a condition, heat applied for fixing is always concentrated on a predetermined portion of the cartridge. Since the cartridge container is made of plastic, the temperature rise of the cartridge container at this location may cause deformation due to thermal expansion of the cartridge container. The cause of the deformation is due to the temperature difference between the inner surface and the outer surface of the cartridge adjacent to the fixing means, and an actual measurement example is shown below. Room temperature 24.3 ° C
In the continuous durability test in, the average temperature of the outer surface and the inner surface of the cartridge container is 58.2 ° C and 49.7 ° C, respectively,
This temperature difference did not depend on room temperature and was always kept at about 8 ° C to 10 ° C. Since the temperature difference of about 9 ° C. is applied to the plastic cartridge container, the cartridge container itself may be bent due to the difference in expansion coefficient.

When the cartridge container is deformed, the cleaning blade adhered and fixed to the cartridge container may bend and may not come into contact with the photosensitive drum with a predetermined pressing force, or a part of the photosensitive drum may be bent due to excessive bending. It is conceivable that a phenomenon may occur in which there is a risk of not contacting the. As a result, the residual toner and paper dust on the surface of the photosensitive drum are not sufficiently cleaned and remain on the surface of the photosensitive drum, resulting in poor charging, which may deteriorate the image quality.

[0006]

A typical structure of the present invention is, in a process cartridge attachable to and detachable from an image forming apparatus main body, a frame, an image carrier, and process means acting on the image carrier. A process cartridge, comprising: a heat insulating layer provided on the frame body located on the fixing unit side provided on the image forming apparatus main body side when mounted on the image forming apparatus main body.

Still another typical configuration of the present invention is an image forming apparatus capable of mounting a process cartridge and forming an image on a recording medium, wherein a frame, an image carrier and the image carrier are provided. A process cartridge having a working process unit and a heat insulating layer provided on the frame body located on the fixing unit side provided on the image forming apparatus main body side when attached to the image forming apparatus main body can be attached Mounting means and fixing means for fixing the image on the recording medium,
An image forming apparatus comprising:

[0008]

According to the present invention, the deformation of the process cartridge frame due to heat can be suppressed.

[0009]

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

The embodiment described below is a cartridge in which the image carrier and the process means are incorporated in one unit, and a heat insulating layer is provided in the cartridge container adjacent to the fixing means, or the cartridge container is provided on the outer surface or inside thereof. It is a material with a small coefficient of thermal expansion.

That is, by providing a heat insulating layer in the cartridge container adjacent to the fixing means, the deformation of the cartridge container due to heat is alleviated, or by disposing a material having a small thermal expansion coefficient on the outer surface or inside of the cartridge container. , Even if the temperature of the cartridge container itself rises, the deformation of the cartridge container is suppressed by the member having a low coefficient of thermal expansion,
The bending of the cleaning blade can be prevented in advance.

(First Embodiment) FIG. 1 is a diagram of a main portion showing a state in which an air layer A is provided as a heat insulating layer inside the cartridge adjacent to the fixing means 5 according to this embodiment. That is, the air layer A is provided in the cartridge container located on the fixing unit side provided on the image forming apparatus main body side when mounted on the image forming apparatus main body.

In FIG. 1, reference numeral 1 is a rotary drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) as an image bearing member. The photosensitive drum 1 is charged to a predetermined potential by the charging means 2 and then exposed by the laser beam L, and the electrostatic latent image formed thereon is toner-developed (visualized) by the developing means 3. The toner image is transferred onto the image transfer material P conveyed by the transfer means 4 at an appropriate timing, and then about 180 by a thermistor.
The toner image is fixed on the transfer material P by the image fixing means 5 which is heated and held at .degree.

After the image is transferred, the cleaning means 6 cleans the toner and the paper dust of the image transfer material, which remains on the surface of the photosensitive drum without being transferred. The cleaning member is of a blade cleaning type, and the front edge 6b of the cleaning blade 6 is attached to the photosensitive drum 1
Is abutted with a predetermined pressing force in the direction of the surface movement of the counter. In this embodiment, the charging unit 2 is a charging roller that is rotated by the photosensitive drum 1, and the developing unit 3 is a developing sleeve, and the toner stored in the toner storing unit 3a is used for developing. 3b is a stirring roller, 3
c is a doctor blade. Further, the fixing unit 5 has a heating roller 5a and a pressure roller 5b, and 5c is a heater.

The cleaning blade 6 in this embodiment is made of ester polyurethane rubber, and the cleaning blade 6 is attached to the SUS plate 6a.
The SUS plate 6a is integrated with the support wall 7c of the cartridge container 7 by fixing it with a screw 7d. Further, the cleaning blade 6 is different from the photosensitive drum 1 in the photosensitive drum 1
The cleaning is accomplished by contacting the photosensitive drum 1 with a contact angle of 25 ° and a contact width of 1 mm in the counter direction in the rotation direction (counterclockwise direction).

Conventionally, the front surface of the cartridge expands and deforms in a convex shape in the longitudinal direction of the fixing means due to the heat of the fixing device.
As a result, the cleaning blade 6 also bends in a convex shape following the shape, and the contact pressure at the central portion of the cleaning blade 6 becomes small, which may cause cleaning failure.

However, when an air layer having a thickness of 5 to 10 mm is provided as a heat insulating layer in the cavity between the cartridge container walls 7a and 7b according to the present embodiment as shown in FIG. 1, the air layer has a heat insulating effect. Since the cartridge container wall 7b has a mechanism that alleviates the thermal expansion and deformation of the cartridge container wall 7a, the deformation that leads to the bending of the cleaning blade 6 is suppressed as a whole.

An endurance test was actually conducted with the configuration of this embodiment. The test condition is that the control temperature of the fixing unit is 180 ° C,
A printer that can record up to B4 sheets, 8 sheets per minute A
Four sheets of paper were continuously used for 6000 sheets, which is the life of the cartridge, and kept durable in an environment of normal temperature and normal humidity.

In the case of a conventional cartridge not provided with a heat insulating layer, the deterioration of the image quality caused by the defective charging at the center of the image was recognized intermittently from about 2000 sheets (about 4 hours after the start of the durability). In the case of the cartridge provided with the air layer A as the heat insulating layer according to the present embodiment, deterioration of the image quality due to the bending of the cleaning blade 6 was not recognized until the end of the durability.

Although the air layer A is provided as the heat insulating layer in this embodiment, a method of filling a liquid (water or the like) or ceramics (alumina particles or the like) in addition to air as the heat insulating member may be considered. As for the selection of these materials, it is possible to select a suitable material in accordance with the conditions such as the fixing temperature, the apparatus configuration or the manufacturing process.

Therefore, by providing an air layer in the portion of the cartridge container wall 7, it is possible to alleviate the influence of heat of the fixing means 5 and always exhibit stable cleaning performance, and to maintain stable image quality. It could be confirmed.

(Second Embodiment) The present embodiment is characterized in that a metal member having a small coefficient of thermal expansion is arranged on the outer surface of the cartridge container 7, and FIG. 2 is a schematic view thereof.

In the previous embodiment, the cartridge container 7
Since a heat insulating layer (air layer A) is provided in the structure, a special manufacturing process is required.

Therefore, in this embodiment, in order to prevent the deformation of the cartridge container 7 and to simplify the manufacturing process, a linear heat is applied to the cartridge container wall 7e facing the fixing means 5 on the device body side when mounted on the device body. A member N having a small expansion coefficient was attached. As a member N having a small coefficient of linear thermal expansion, an Invar alloy of Ni steel (length 270 mm, width 10 mm, thickness 2 mm) was held, and several fixing units 5 were mounted along the longitudinal direction. At the time of mounting, screws (not shown) were used to fix the Invar alloy and the cartridge in order to improve the mountability. The Invar alloy is Fe-36 wt% Ni (-0.4 wt% Mn
It has a composition of −0.2 wt% C) and has a coefficient of thermal expansion coefficient of about 1.2 × 10 ⁻⁶ / K at room temperature. Therefore, even if the temperature changes from room temperature (25 ° C., 298K) to the fixing temperature (180 ° C., 453K), expansion can be suppressed by 1 mm or less per unit length, so that the deformation of the cartridge container can be avoided. .

An endurance test similar to that of the previous embodiment was conducted under this embodiment. As a result of stable cleaning without deformation of the cartridge container and bending of the cleaning blade 6 until the end of the endurance, an image such as a black streak is obtained. No quality deterioration was observed.

Therefore, by mounting a member having a small coefficient of thermal expansion on the outer surface or the inner surface of the cartridge container, it is possible to avoid the deformation of the cartridge container and the bending of the cleaning blade 6, thereby simplifying the manufacturing process. It was confirmed that this could be achieved.

(Third Embodiment) This embodiment is characterized in that a ceramic material C having a small coefficient of thermal expansion and a heat insulating effect is arranged on the outer surface or inner surface of the cartridge container, and FIG. It is the block diagram.

In the present embodiment, plate-shaped asbestos was used as the ceramic material C. Since this plate-shaped asbestos has a small coefficient of thermal expansion of 7 × 10 ^-6 / K, it is hardly subjected to thermal deformation, and its thermal conductivity is 0.3 (wm ^-1 K ^-1 ), so it transmits almost all heat. It has the characteristic that it does not exist.

[0029] Asbestos made into a plate shape is actually 270 mm long x
A shape of a width of 50 mm and a thickness of 3 mm was adhered to the wall 7 of the cartridge container, and the same experiment as the previous example was conducted. According to the present embodiment, the deterioration of the image quality due to the bending of the cleaning blade 6 was not recognized until the end of the durability, and the temperature of the inner surface of the cartridge container was further measured to find that it was 29.6 ° C. against the room temperature of 25.2 ° C. However, it can be seen from the fact that the temperature was 48.7 ° C. in the case of the cartridge not subjected to the present example, and it was found that the heat insulation was sufficient.

Therefore, according to the present embodiment, it was confirmed that the heat insulation / non-expansion effect to the cartridge container is surely exhibited, and the image quality can be maintained and the damage to the cartridge container can be reduced.

According to each of the above-described embodiments, the cartridge container adjacent to the fixing means is provided with a heat insulating layer, or a material having a small coefficient of thermal expansion is arranged on the outer surface or inside of the cartridge container to expand the cartridge container. There is an effect that the bending of the cleaning blade due to the deformation can be avoided, and the toner, paper dust, etc. on the drum surface can always be stably removed.

Next, one embodiment of an image forming apparatus to which the process cartridge according to each of the above-described embodiments can be mounted will be specifically described with reference to the drawings.

FIG. 4 is a side sectional explanatory view of a laser beam printer which is one mode of the image forming apparatus according to this embodiment.

Now, an overall schematic structure of the image forming apparatus equipped with the process cartridge to which each of the above-described embodiments is applied will be described.

This image forming apparatus A is, as shown in FIG.
An optical image based on image information is emitted from the optical system 100 to form a developed (hereinafter referred to as toner) image on the photosensitive drum 1 which is an image carrier. Then, in synchronization with the formation of the toner image, the recording medium P is conveyed upward by the conveying means 103, and the toner image formed on the photoconductor drum 1 in the image forming portion formed as the process cartridge B is transferred to the transfer means 4. Then, the recording medium P is transferred to the fixing means 5 and the transferred toner image is fixed and discharged to the upper discharging portion 106.

Next, the structure of each part of the image forming apparatus A will be described.

[Image Forming Apparatus] The configuration of each part of the image forming apparatus A will be described in the order of the optical system, the conveying means, the transfer means, the fixing means, and the cartridge mounting means.

(Optical System) The optical system 100 irradiates a light image on the photosensitive drum 1 by irradiating light on the basis of image information read from an external device or the like. As shown in FIG. A laser diode 101b and a polygon mirror 101 are provided in an optical unit 101a of 113.
c, a scanner motor 101d, and an imaging lens 101e are stored.

When an image signal is given from an external device such as a computer or a word processor, the laser diode 101b emits light according to the image signal,
The polygon mirror 101c is irradiated with image light. The polygon mirror 101c is rotated at a high speed by a scanner motor 101d, and the image light reflected by the polygon mirror 101c is irradiated onto a rotating photosensitive drum 1 through an imaging lens 101e to selectively expose the surface of the drum 1. Then, a latent image corresponding to the image information is formed.

(Recording Medium Conveying Means) Next, the constitution of the conveying means 103 for conveying the recording medium P (for example, recording paper, OHP sheet, cloth or thin plate) will be described. Figure 4
As shown in FIG.
The recording medium P in the cassette 108a has a mounting portion 8a.
Are fed one by one from above by the pickup roller 108b so as to hit the pair of registration rollers 108c1 and 108c2. And the registration roller pair 108c
1, 108c2 are driven and rotated according to the image forming operation to convey the recording medium P to the image forming unit. Further, the recording medium P after the image formation is conveyed to the fixing means 5, and the discharge roller 1
The sheet is discharged to the discharging section 106 by 08d1 and 108d2.

(Transfer Means) The transfer means 4 is for transferring the toner image formed on the photosensitive drum 1 in the image forming section onto the recording medium P, and the transfer means of this embodiment transfers as shown in the figure. It is composed of rollers 4. That is, the recording medium P is pressed against the photosensitive drum 1 of the mounted process cartridge B by the transfer roller 4, and a voltage having a polarity opposite to that of the toner image formed on the photosensitive drum 1 is applied to the transfer roller P. The toner on the photosensitive drum 1 is transferred to the recording medium P.

(Fixing Means) Fixing Means 5 The Transfer Roller 4
The toner image transferred on the recording medium P is fixed by the voltage application. As shown in the figure, the structure has a driving roller 5a that is driven and rotated, and a heater 5c inside,
The drive roller 5a and the fixing roller 5b that is driven to rotate by being pressed against the drive roller 5a. That is, when the recording medium P onto which the toner image has been transferred in the image forming section passes between the driving row 5a and the fixing roller 5b, pressure is applied by the pressing of both rollers 5a and 5b, and heat generation of the fixing roller 5a occurs. Heat is applied by the toner, and the toner on the recording medium P is fixed on the recording medium 2.

(Process Cartridge Mounting Unit) Inside the image forming apparatus A, a cartridge mounting unit for mounting the process cartridge B is provided. The process cartridge B is attached to and detached from the apparatus main body 113 by opening the front unit 114. That is, the device body 1
A front unit 114, which can be opened and closed by a hinge 114a, is attached to the upper part of 13. As shown in FIG. 4, when the front unit 114 is opened, a cartridge mounting space is provided in the apparatus main body 113, and left and right guide members (not shown) are attached to the left and right inner wall surfaces of the main body. The left and right guide members are provided with guides for inserting the process cartridge B. The process cartridge B is inserted along the guides, and the front unit 114 is inserted.
The process cartridge B is attached to the image forming apparatus A by closing the.

{Process Cartridge} Next, the structure of each part of the process cartridge B mounted in the image forming apparatus A will be described.

The process cartridge B is provided with an image carrier and at least one process means. Here, the process means includes, for example, a charging means for charging the surface of the image carrier, a developing means for forming a toner image on the image carrier, and a cleaning means for cleaning the toner remaining on the surface of the image carrier. As shown in the figure, in the process cartridge B of this embodiment, a charging unit 2, an exposing unit 9, a developing unit 10, and a cleaning unit 11 are arranged around an electrophotographic photosensitive drum 1 which is an image carrier.
These are covered with a housing composed of a frame 12 to be integrated with each other, and are configured to be attachable to and detachable from the apparatus main body 13.

Next, the structure of each part of the process cartridge B will be described in the order of the photosensitive drum 1, the charging means 4, the exposing part 9, the developing means 3 and the cleaning means 6.

(Photoreceptor Drum) The photoreceptor drum 1 according to this embodiment has an organic photosensitive layer coated on the outer peripheral surface of a cylindrical drum base made of aluminum. This photoconductor drum 1
Is rotatably attached to the frame body 7, and the driving force of a drive motor provided on the apparatus main body side is transmitted to a gear (not shown) fixed to one end of the drum 1 in the longitudinal direction. Rotate in the direction of the arrow in the figure according to the image forming operation.

(Charging means) The charging means is for uniformly charging the surface of the photosensitive drum 1, and in this embodiment, the charging roller 2 is rotatably attached to the frame body 7.
The so-called contact charging method is used. The charging roller 2 has a metal roller shaft 2a provided with a conductive elastic layer, a high resistance elastic layer further provided thereon, and a protective film provided on the surface thereof. The conductive elastic layer is formed by dispersing carbon in an elastic rubber layer such as EPDM or NBR and has a function of guiding a bias voltage supplied to the roller shaft 2a. The elastic layer having a high resistance is made of urethane rubber or the like and contains a minute amount of conductive fine powder as an example. Even when a charging roller having a high conductivity such as a pinhole of the photoconductor drum 1 faces each other, the leak current to the photoconductor drum 1 is limited to prevent an abrupt drop of the bias voltage. The protective layer is N-
It is made of methylmethoxylated nylon so that the plastic material of the conductive elastic layer or the elastic layer of high resistance does not touch the photoconductor drum 7 and touch the photoconductor drum 7 to deteriorate the surface of the photoconductor drum 7. Act on.

The charging row 2 is brought into contact with the photosensitive drum 1, and the charging row 2 rotates following the rotation of the photosensitive drum 1 during image formation. At this time, a DC voltage and an AC voltage are applied to the charging roller 2. By superimposing and applying, the surface of the photosensitive drum 1 is uniformly charged.

(Exposure Unit) The exposure unit 9 exposes the surface of the photosensitive drum 1 uniformly charged by the charging roller 2 with an optical image irradiated from the optical system 100 to form an electrostatic latent image on the surface of the drum 1. And an optical path 9 for guiding the optical image is provided above the developing means 3 to form an exposure section. The charging roller 2 and the cleaning unit 6 are arranged above the optical path 9, and the developing unit 3 is arranged below.

(Developing Means) As shown in the drawing, the developing means 3 has a toner reservoir 3a for accommodating the toner t, and a toner feeding member which rotates in the direction of arrow a for feeding the toner into the toner reservoir 3a. 3b is provided. Further, a developing sleeve 3 having a magnet (not shown) inside and forming a thin toner layer on the surface by rotating is provided at a minute interval from the photosensitive drum 1. The minute intervals are formed by attaching spacers (not shown) to both ends of the developing sleeve 3 in the longitudinal direction, and bringing the spacers into contact with the surface of the photosensitive drum 1.

When a toner layer is formed on the surface of the developing sleeve 3, friction between the toner and the developing sleeve 3 provides sufficient triboelectric charge to develop the electrostatic latent image on the photosensitive drum 1. A developing blade 3c is provided to regulate the layer thickness of the toner.

(Cleaning Means) Cleaning Means 6
As shown in the figure, the configuration of No. 2 is as follows: a cleaning blade 6 that comes into contact with the surface of the photosensitive drum 1 and scrapes off the toner remaining on the drum 1, and a blade 6 that scoops off the scraped toner. Sheet 6c located below the sheet and weakly contacting the surface of the photosensitive drum 1
And a waste toner reservoir 6d for storing the scraped waste toner.

The process cartridge is a cartridge in which the charging means, the developing means or the cleaning means and the electrophotographic photosensitive member are integrally formed, and the cartridge can be attached to and detached from the main body of the image forming apparatus. Further, at least one of the charging means, the developing means, and the cleaning means and the electrophotographic photosensitive member are integrally made into a cartridge so that it can be attached to and detached from the main body of the image forming apparatus.
Further, it means that at least the developing means and the electrophotographic photosensitive member are integrally made into a cartridge so as to be attachable to and detachable from the apparatus main body.

[0055]

As described above, according to the present invention, the deformation of the process cartridge frame due to heat can be suppressed. Further, since it becomes possible to mount the process cartridge close to the fixing means, the apparatus main body can be downsized.

[Brief description of drawings]

FIG. 1 is a side sectional view of a process cartridge according to an embodiment of the present invention.

FIG. 2 is a side sectional view of a process cartridge according to an embodiment of the present invention.

FIG. 3 is a side sectional view of a process cartridge according to an embodiment of the present invention.

FIG. 4 is a side sectional view of a laser beam printer to which a process cartridge to which an embodiment of the present invention is applied can be mounted.

[Explanation of symbols]

 1 Electrophotographic Photoreceptor (Photosensitive Drum) 2 Charging Means 3 Developing Means 4 Transfer Means 5 Fixing Means 6 Cleaning Means 7 Cartridge Container A Air Layer N-Line Thermal Expansion Coefficient Member (Ni Steel Invar Alloy) C Ceramic Material

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Claims (11)

[Claims] 1. A process cartridge attachable to and detachable from an image forming apparatus main body, wherein a frame, an image bearing member, a process unit acting on the image bearing member, and an image forming unit when mounted on the image forming apparatus main body. A process cartridge, comprising: a heat insulating layer provided on the frame body, which is provided on a side of the fixing device, which is provided on a main body side of the apparatus. 2. The process cartridge according to claim 1, wherein the heat insulating layer is an air layer in the cavity of the frame body. 3. The process cartridge according to claim 1, wherein the heat insulating layer is a member having a low coefficient of thermal expansion provided on the frame body. 4. The process cartridge according to claim 1, wherein the heat insulating layer is a member having a low thermal conductivity provided on the frame body. 5. The process cartridge integrally comprises a charging unit, a developing unit or a cleaning unit as the process unit and an electrophotographic photosensitive member as the image carrier, and the cartridge is incorporated in an image forming apparatus main body. The process cartridge according to claim 1, wherein the process cartridge is removable. 6. The process cartridge comprises at least one of a charging unit, a developing unit, and a cleaning unit as the process unit, and an electrophotographic photosensitive member as the image bearing member, which are integrally formed into a cartridge to form an image forming apparatus main body. The process cartridge according to claim 1, wherein the process cartridge is removable. 7. The process cartridge is configured such that at least a developing unit as the process unit and an electrophotographic photosensitive member as the image carrier are integrally made into a cartridge so as to be attachable to and detachable from an image forming apparatus main body. The process cartridge according to claim 1, wherein the process cartridge is provided. 8. An image forming apparatus capable of mounting a process cartridge and forming an image on a recording medium, comprising: a frame, an image carrier, a process unit acting on the image carrier, and an image forming apparatus main body. Mounted on the image forming apparatus main body side, a heat insulating layer provided on the frame body located on the fixing means side provided on the image forming apparatus main body side; An image forming apparatus comprising: a fixing unit for fixing. 9. The image forming apparatus according to claim 8, wherein the fixing unit is a heat fixing unit. 10. The image forming apparatus according to claim 8, wherein the image forming apparatus is an electrophotographic copying machine. 11. The image forming apparatus according to claim 8, wherein the image forming apparatus is a laser beam printer.