JP2006208673A - Image forming unit and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming unit which cools a developing roller, a photoconductor and the like in the image forming unit to prevent deterioration of image quality.
SOLUTION: A photoconductor 11, a charging device 12 for applying a uniform potential to the surface of the photoconductor 11, a developing roller 13 for attaching a developer to an electrostatic latent image written on the charged photoconductor 11, and the like. , A supply roller 14 for supplying the developer to the developing roller 13, a developing blade 15 for regulating the layer thickness of the developer on the developing roller 13, and the developer remaining after the transfer to the recording medium is removed from the surface of the photoreceptor 11. In the image forming apparatus having the image forming unit including the cleaning unit 17 that passes through the image forming unit, the image forming unit passes through the image forming unit parallel to the axial direction of the developing roller 13, and has openings at both ends of the image forming unit. A cooling duct 21 having a hollow structure through which gas can flow is provided.
[Selection] Figure 2

Description

  The present invention relates to an image forming apparatus and an image forming unit that print an image on a recording medium by an electrophotographic method using a developer.

  An electrophotographic image forming apparatus that uses a developer is, for example, a drive system component such as a motor, a rotor, or a belt used for transporting a printing medium (paper), or an electrostatic latent image formed on a photoconductor. An image forming unit that forms a toner image developed with toner, a transfer unit that transfers the toner image onto a print medium, an image fixing unit that pressurizes and fixes the toner image on the recording medium while heating, and generated inside the apparatus It has a cooling fan that discharges heat to the outside.

  Originally, the image forming apparatus generates heat by the image fixing unit as described above, and heat is discharged to the outside by a cooling fan. However, in recent years, there has been a demand for particularly high functionality and high speed. Therefore, the amount of heat generated inside is increasing, and not only the image fixing means but also other heat generation is increasing. That is, not only the amount of heat generated by the image fixing means increases due to the increase in speed, but also the heat generation due to the increase in the rotational speed of the drive system motor and rotor or the moving speed of the belt increases.

  For example, the heat generating portion in the image forming unit includes a stirring device that stirs toner, a supply roller that charges the developing rotor and supplies the toner, a developing rotor seal material, a developing blade that aligns the toner thickness of the developing roller, and a photoreceptor ( Cleaning means). At the nip portion between the developing roller and the supply roller, both rollers rotate so as to rub against each other in the opposite direction, and a seal material and a developing blade are in contact with and rub against the developing roller. At the nip portion between the photosensitive member (roller) and the roller of the charging device, both rollers rotate so as to rub against each other in the opposite direction, and the photosensitive member is rubbed against the cleaning member. Further, at the nip portion between the photosensitive member (roller) and the developing roller, both rollers rotate so as to be in the same direction, but the developing roller rotates (peripheral speed) and is rubbed because it is faster. As described above, heat due to sliding friction is generated in each of the nip portions and the contact portions described above, and the frictional heat generated in each nip portion and the contact portion is increased due to the increase in speed.

  A particular problem with the generation of frictional heat in the image forming unit is when frictional heat above the melting temperature of the toner has occurred. In this case, for example, filming due to temperature rise in the toner supplied on the developing roller. When the phenomenon occurs and the image quality of the toner image formed on the photoreceptor deteriorates, the image quality of the image finally transferred to the print medium may also deteriorate.

  In response to the temperature rise of the toner in the image forming unit, for example, the shaft of the stirring device in the image forming unit is formed as a cavity (hollow structure) open at both ends, and the shaft of the stirring device is cooled by air from the inside. There is a known method (see, for example, Patent Document 1).

JP-A-10-239965 (page 1-3, FIG. 2)

  However, in the method described in Patent Document 1, only the peripheral portion of the stirring device in the image forming unit can be cooled, but the peripheral portion of other frictional heat generation sites such as a developing roller and a photoconductor that generate a relatively large amount of heat is generated. It cannot be cooled. Accordingly, there is a problem in that it is impossible to prevent other frictional heat generation sites such as the developing roller and the photoconductor from exceeding the melting temperature of the toner, and the image quality deterioration due to the filming phenomenon cannot be solved.

  The present invention has been made in order to solve the above-described problems, and cools the generation sites of frictional heat, such as a developing roller and a photoconductor, in the image forming unit, which generate a relatively large amount of heat, and generates each generation site. An object of the present invention is to provide an image forming unit and an image forming apparatus that prevent deterioration of image quality by preventing the temperature from becoming higher than the melting temperature of the toner.

In order to achieve the above-described object, an image forming unit of the present invention includes a photoconductor, a charging device that applies a uniform potential to the surface of the photoconductor, and an electrostatic latent image written on the charged photoconductor. A developing roller that attaches the developer to the developing roller, a supply roller that supplies the developer to the developing roller, a developing blade that regulates the layer thickness of the developer on the developing roller, and the developer that remains after transfer to the recording medium In an image forming unit comprising a cleaning means for removing the toner from the surface of the photoreceptor,
The image forming unit is provided with a hollow structure portion that passes through the image forming unit in parallel with the axial direction of the developing roller, has openings at both ends of the image forming unit, and is hollow inside.

Alternatively, the image forming unit has a hollow structure that passes through the image forming unit in parallel with the axial direction of the photoconductor, has openings at both ends of the image forming unit, and allows gas to flow inside. A cooling roller is provided that is rotatably supported without blocking, and is in contact with the photosensitive member between the cleaning means and the charging device.
The image forming apparatus according to the present invention includes the above-described image forming unit.

  In the image forming apparatus of the present invention, a cooling duct or a cooling roller having openings at both ends is provided so as to penetrate the image forming unit, so that the heat generation amount of the image forming unit is relatively large. The developing roller and the photosensitive member can be cooled, and deterioration of the image quality can be prevented by preventing the developing roller and the photosensitive member from exceeding the melting temperature of the toner.

  The image forming apparatus of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a longitudinal sectional view showing an image forming apparatus according to Embodiment 1 of the present invention.
In FIG. 1, a paper feed unit 1, a print timing adjustment unit 3, an image forming unit 4, a transfer unit 5, and an image fixing unit 6 are driving parts such as rollers or belts in a medium carry-out conveyance path 7, a discharge roller pair 8, and the like. Are driven by a drive system (not shown). The paper feed unit 1 feeds the recording medium stored in the paper feed cassette 2 toward the print timing adjustment unit 3. The print timing adjustment unit 3 adjusts the timing of feeding the recording medium to the image forming unit 4 so that the image is transferred onto the recording medium.

  The image forming unit 4 is a unit that forms an image to be transferred onto a recording medium, and is detachably disposed in the image forming apparatus. The configuration and operation of the image forming unit 4 will be described later. The transfer unit 5 is a unit that transfers the image formed by the image forming unit 4 to a recording medium and conveys the recording medium onto which the image has been transferred to a subsequent image fixing unit 6.

  The image fixing unit 6 includes a pair of roller members that press the recording medium on which the image is transferred, and a heating element provided inside at least one roller member that heats the recording medium while pressing. The medium carry-out conveyance path 7 is a conveyance path for conveying the recording medium on which the image is fixed by the image fixing unit 6 to the discharge roller pair 8 at the subsequent stage. The discharge roller pair 8 discharges the recording medium on which the image is fixed from the medium discharge unit 9 to the outside of the apparatus. In this way, the image forming process on the recording medium is completed.

  The cooling fan 10 is provided to discharge heat generated in the image forming apparatus to the outside of the apparatus. In general, in an electrophotographic image forming apparatus, the image fixing unit 6 generates the largest amount of heat, so that the heat from the image fixing unit 6 is disposed in the vicinity so as to be efficiently discharged. The image forming apparatus is provided with an intake port (not shown) that is an opening for sucking outside air and an exhaust port (not shown) that is an opening for discharging air inside the image forming apparatus. The cooling fan 10 is provided at the exhaust port and discharges internal heat together with the air in the image forming apparatus. The shape of the air inlet is arbitrary and may be plural. The exhaust port is provided, for example, on the opposite side of the air intake port with the heat generating portion interposed therebetween, and the cooling fan 10 is installed there to discharge the air that has cooled the heat generating portion with the air flowing in from the air intake port. Can do.

2 is a longitudinal sectional view showing an image forming unit in the image forming apparatus of FIG. 1, and FIG. 3 is a perspective view of the image forming unit of FIG.
The photoreceptor 11 is a roller-shaped device on which an image is formed, and is configured by covering the surface of a conductive base layer made of roller-like aluminum or the like with a surface layer made of an organic photoreceptor. An outer peripheral surface of the charging device 12, which will be described later, an outer peripheral surface of the developing roller 13, and a cleaning unit 17 are disposed on the outer peripheral surface of the photoconductor 11. The photoconductor 11 has high heat dissipation because the conductive base layer is made of aluminum or the like having high thermal conductivity.

  The charging device 12 is a device that applies a uniform potential to the surface of the photoconductor 11, and is formed on a surface of a conductive metal shaft so that semiconductive rubber such as epichlorohydrin rubber covers the roll. . The outer peripheral surface of the charging device 12 is in contact with the outer peripheral surface of the photoconductor 11. The nip portion between the photosensitive member (roller) 11 and the roller of the charging device 12 is heated so that both rollers rotate so as to rub against each other in the opposite directions.

  The developing roller 13 is a device that develops a toner image by supplying a developer (toner) to the electrostatic latent image written on the charged photosensitive member and depositing it on the surface of the conductive metal shaft. On top, a semiconductive rubber such as silicone is formed to cover. The outer peripheral surface of the developing roller 13 is in contact with the outer peripheral surface of the photoconductor 11, the outer peripheral surface of a supply roller 14 described later, the developing blade 15, and the sealing material 16. The developing roller 13 is driven to rotate counterclockwise in FIG. 2 by a rotation driving member (not shown). Further, at the nip portion between the photoconductor (roller) 11 and the developing roller 13, both rollers rotate so that they are in the same direction, but the developing roller 13 rotates (peripheral speed) because it is faster. The cage contact portion generates heat. Since the heat generation amount of the developing roller 13 is large, the temperature rise also increases.

  The supply roller 14 is a device that supplies a constant amount of toner to the developing roller 13, and covers the surface of the conductive metal shaft with rubber added with a foaming agent during kneading in order to improve toner transportability. Formed as follows. The supply roller 14 is driven to rotate counterclockwise in FIG. 2 by a rotation drive member (not shown). Therefore, the nip portion between the developing roller 13 and the supply roller 14 generates heat at the abutting portion because both rollers rotate so as to rub against each other in opposite directions. The nip portion between the developing roller 13 and the supply roller 14 is the largest heat source in the image forming unit 4 and the temperature rise is large.

  The developing blade 15 regulates the thickness of the thin toner layer supplied onto the developing roller 13 to be uniform. The developing blade 15 contacts the outer peripheral surface of the developing roller 13 or the toner thin layer thereon. Since the developing blade 15 is in contact with the developing roller 13 and rubs, the contact portion generates heat. The developing blade 15 is a relatively large heat generation source in the image forming unit 4, and the temperature rise is also relatively large. The seal material 16 is a seal material for preventing the developer supplied from the supply roller 14 from leaking out of the unit from the supply receiving portion in the development roller 13, and abuts on the outer peripheral surface of the development roller 13. Since the sealing material 16 is in contact with the developing roller and rubs, the contact portion generates heat.

  The cleaning unit 17 contacts the outer peripheral surface of the photoconductor 11 after the toner image is transferred to the recording medium, and scrapes and removes (cleans) the remaining toner. Since the cleaning means 17 contacts and rubs against the photoconductor 11, the contact portion generates heat. The cleaning means 17 is a relatively large heat source in the image forming unit 4 and the temperature rise is relatively large. The light emitting device 18 removes the residual potential by irradiating the surface of the photoreceptor 11 cleaned by the cleaning unit 17 with light. The developer cartridge 19 contains a developer and is detachably disposed on the image forming unit 4, and supplies the developer to the image forming unit 4.

  The stirring device 20 is a device that uniformly disperses the developer supplied from the developer cartridge 19 in the image forming unit, and has a shaft and has a spiral shape on the surface thereof. For example, when the shaft has a hollow structure in which both ends are opened as shown in the prior art, the shaft of the hollow structure can flow by replacing the internal air with the external air. Inside the image forming apparatus, an air flow (airflow) is generated by the cooling fan 10, and the stirring device 20 can be cooled by causing the air inside the hollow shaft to flow by the air flow. Therefore, the toner around the stirring device 20 can also be cooled.

  The cooling duct 21 has a function of a duct for allowing air to flow in order to cool the inside of the image forming unit. The cooling duct 21 penetrates the image forming unit 4 in parallel with the axial direction of the developing roller 13, and both ends of the image forming unit 4. The shape of the through hole is provided with a cooling duct opening 22 (see FIG. 3). The cooling duct 21 is thus formed with a hollow structure in which gas can flow inside.

  The cooling duct 21 in the present embodiment is generally formed so as to have a substantially rectangular cross-sectional shape as shown in FIG. 2, and a nip portion between the photoconductor 11 and the developing roller 13 (first It is arranged in the vicinity of the nip part). Further, the cooling duct 21 has a pointed portion 121 in which one corner of a substantially quadrangular shape is projected (convex) toward the nip portion (first nip portion) between the photosensitive member 11 and the developing roller 13. Is formed.

  The cooling duct 21 (particularly, the front end portion 121) is provided with an interval so as not to come into contact with either the photoconductor 11 or the developing roller 13. The interval is set as much as possible in order to improve the cooling efficiency. Installed to be small (minimal).

  As described above, since the air flow is generated by the cooling fan 10 inside the image forming apparatus, the air inside the cooling duct 21 that is a through hole can be caused to flow by the air flow. Thereby, the cooling duct 21 can be cooled.

  The thickness dimension of the pipe portion of the cooling duct 21 is desirably formed as thin as possible, and at least the thickness dimension of the tip 121 is preferably formed as thin as possible. This is for efficiently cooling the periphery of the cooling duct 21, and in particular, when the material forming the cooling duct 21 is a material that does not conduct the temperature well, in order to improve the cooling efficiency, It is preferable to form the thickness dimension as thin as possible.

  For example, as shown in FIGS. 2 and 3, the cooling duct 21 is formed by molding or the like so as to be integrated with the housing of the image forming unit 4 using a polymer material such as plastic, for example. The thermal conductivity (λ) of the polymer material is better than that of a metal having good thermal conductivity such as copper (about 370 W / mk) or aluminum alloy (about 200 W / mk). No (for example, the thermal conductivity (λ) of PVC is about 0.17 W / mk). Therefore, when the thickness dimension of the cooling duct 21 that is molded is increased, the cooling efficiency of the developing roller 13 and the photosensitive member 11 may be reduced even if the inside of the cooling duct 21 is cooled by an air flow. Therefore, it is preferable that the thickness dimension of the pipe portion of the cooling duct 21, particularly the thickness dimension of the pipe portion of the tip 121, be formed as thin as possible in order to improve the cooling efficiency.

  In the above-described embodiment, the cooling duct 21 is formed to have a substantially square cross-sectional shape. However, the shape of the embodiment is not limited to this, and the present embodiment can be implemented as long as the tip portion 121 is provided. Since the effect of the form can be obtained, there is no need to define the cross-sectional shape other than the provision of the tip portion 121. Further, in the above-described embodiment, the cooling duct 21 is disposed below the nip portion between the photoconductor 11 and the developing roller 13, and the front end portion 121 projects from the lower portion toward the upper nip portion. However, for example, it may be arranged above the nip portion between the photoconductor 11 and the developing roller 13 so that the tip 121 protrudes from the upper side toward the lower nip portion.

  As described above, in the image forming apparatus according to the present embodiment, the interior of the image forming unit 4 is parallel to the axial direction of the developing roller 13 toward the nip portion (first nip portion) between the photosensitive member 11 and the developing roller 13. Since the through-hole-shaped cooling duct 21 having the tip 121 is provided, the flow of air by the cooling fan 10 causes the photoconductor 11 with high heat conductivity and high heat dissipation, and the temperature rise and heat generation are large. Aiming at the nip portion of the developing roller 13, the heat generated by the friction and radiated or conducted to the outside is absorbed through the cooling duct 21 and released to the outside. Since it is possible to avoid a situation in which the temperature rises to a level at which the upper toner filming, it is possible to prevent image quality deterioration.

Embodiment 2. FIG.
FIG. 4 is a longitudinal sectional view showing an image forming unit in the image forming apparatus according to the second embodiment of the present invention.
The difference between the present embodiment and the first embodiment shown in FIG. 2 and the like is that the shape of the cooling duct 21a is changed and the nip portion (second nip portion) between the developing roller 13 and the supply roller 14 is changed. A pointed portion 122 that is arranged in the vicinity and protrudes (convex shape) from one corner of a substantially square shape in cross-section toward the nip portion (second nip portion) between the developing roller 13 and the supply roller 14. It is a point to have. Other configurations are the same as those in the first embodiment.

  The cooling duct 21a has a duct function, is parallel to the axial direction of the developing roller 13, and has a through-hole shape (hollow structure) provided with cooling duct openings 22 at both ends. It is the same as in the first embodiment that it is formed to have a cross-sectional shape. In addition, the cooling duct 21a has a pointed portion 122 having one corner portion of a substantially square shape protruding (convex shape) in a sectional shape toward the nip portion (second nip portion) between the developing roller 13 and the supply roller 14. Is formed.

  The cooling duct 21a (particularly, the front end portion 122) is provided with an interval so as not to contact any of the developing roller 13 and the supply roller 14. The interval is set as much as possible in order to improve the cooling efficiency. Installed to be small (minimal).

  In the above-described embodiment, the cooling duct 21a is formed so as to have a substantially square cross-sectional shape. However, the shape of the embodiment is not limited to this, and the embodiment can be implemented as long as the distal end portion 122 is provided. Since the effect of the form can be obtained, it is not necessary to define the cross-sectional shape other than the provision of the tip portion 122. In the above-described embodiment, the cooling duct 21a is disposed below the nip portion between the developing roller 13 and the supply roller 14, and the front end portion 122 projects from the lower portion toward the upper nip portion. However, for example, it may be arranged above the nip portion between the developing roller 13 and the supply roller 14 so that the front end portion 122 projects from the upper side toward the lower nip portion.

  As described above, in the image forming apparatus according to the present embodiment, the interior of the image forming unit 4 is parallel to the axial direction of the developing roller 13 toward the nip portion (second nip portion) between the developing roller 13 and the supply roller 14. Since the through-hole-shaped cooling duct 21a having the sharp edge 122 is provided, the supply of the developing roller 13 which is the largest heat source and has a large temperature rise in the image forming unit 4 due to the flow of air by the cooling fan 10 is provided. Aiming at the nip portion of the roller 14, the heat generated by the friction and radiated or conducted to the outside is absorbed through the cooling duct 21a and released to the outside, and can be cooled. Therefore, it is possible to prevent the temperature of the toner from rising to a level at which filming occurs, so that deterioration in image quality can be prevented.

Embodiment 3 FIG.
FIG. 5 is a longitudinal sectional view showing an image forming unit in the image forming apparatus according to the third embodiment of the present invention.
The difference between the present embodiment and the first embodiment shown in FIG. 2 and the like is that the arrangement and shape of the cooling duct 21b are changed, and the arrangement is a contact portion between the developing roller 13 and the developing blade 15 (the first portion). It is the point which has the point part 123 which is arrange | positioned in the upper part vicinity of the contact part), and protruded (convex shape) one corner | angular part of a substantially square shape in cross section toward the 1st contact part. Other configurations are the same as those in the first embodiment.

  The cooling duct 21b has the function of a duct, is parallel to the axial direction of the developing roller 13, and has a shape of a through hole (hollow structure) provided with cooling duct openings 22 at both ends. It is the same as in the first embodiment that it is formed to have a cross-sectional shape. Further, the cooling duct 21b has a pointed portion 123 in which one corner of a substantially square shape is projected (convex) toward the contact portion (first contact portion) between the developing roller 13 and the developing blade 15. Is formed.

  The cooling duct 21b (particularly, the front end portion 123) is provided with an interval so as not to contact either the developing roller 13 or the developing blade 15. The interval is set as much as possible to improve the cooling efficiency. Installed to be small (minimal).

  In the above-described embodiment, the cooling duct 21b is formed to have a substantially rectangular cross-sectional shape. However, the shape of the embodiment is not limited to this, and the present embodiment can be implemented as long as the tip portion 123 is provided. Since the effect of the form can be obtained, there is no need to define the cross-sectional shape other than the provision of the tip portion 123.

  As described above, in the image forming apparatus of the present embodiment, the inside of the image forming unit 4 is parallel to the axial direction of the developing roller 13 and is in contact with the developing roller 13 and the developing blade 15 (first contacting portion). Since the through-hole-shaped cooling duct 21b having the pointed portion 123 is provided, the development of a relatively large heat source and a relatively high temperature rise in the image forming unit 4 due to the flow of air by the cooling fan 10 is achieved. Aiming at the contact portion between the roller 13 and the developing blade 15, the heat generated by the friction and radiated or conducted to the outside can be absorbed through the cooling duct 21b and released to the outside to be cooled. Since it is possible to avoid a situation in which the temperature of the toner on the surface rises to a level at which filming occurs, deterioration of the image quality can be prevented.

Embodiment 4 FIG.
FIG. 6 is a longitudinal sectional view showing an image forming unit in the image forming apparatus according to the fourth embodiment of the present invention.
The difference between the present embodiment and the first embodiment shown in FIG. 2 and the like is that the arrangement and shape of the cooling duct 21c are changed, and the arrangement is the contact portion between the photoconductor 11 and the cleaning means 17 (second embodiment). It is the point which has the pointed part 124 which is arranged near the upper part of the contact part), and protrudes (convex shape) one corner of a substantially square shape in cross section toward the second contact part. Other configurations are the same as those in the first embodiment.

  The cooling duct 21c has the function of a duct and is in the shape of a through hole (hollow structure) provided with cooling duct openings 22 at both ends in parallel with the axial direction of the developing roller 13 (or the photoreceptor 11). It is the same as in the first embodiment that it is formed so as to have a substantially rectangular cross-sectional shape. Further, the cooling duct 21c has a pointed portion in which one corner of a substantially quadrangular shape is projected (convex) toward the contact portion (second contact portion) between the photosensitive member 11 and the cleaning unit 17. 124 is formed.

  The cooling duct 21c (particularly, the front end portion 124) is provided with an interval so as not to come into contact with either the photoconductor 11 or the cleaning means 17. The interval is set as much as possible in order to improve the cooling efficiency. Installed to be small (minimal).

  In the above-described embodiment, the cooling duct 21c is formed so as to have a substantially square cross-sectional shape. However, the shape of the embodiment is not limited to this, and the present embodiment can be implemented if the tip portion 124 is provided. Since the effect of the form can be obtained, there is no need to define the cross-sectional shape other than the provision of the tip portion 124.

  As described above, in the image forming apparatus according to the present embodiment, the contact portion (second contact portion) between the photoconductor 11 and the cleaning unit 17 is parallel to the axial direction of the developing roller 13 in the image forming unit 4. Since the cooling duct 21c having a through-hole shape having the tip end portion 124 is provided, the photosensitive member is a relatively large heat source and a relatively large temperature rise in the image forming unit 4 due to the flow of air by the cooling fan 10. Aiming at the contact portion between the body 11 and the cleaning means 17, the heat generated by the friction and radiated or conducted to the outside can be absorbed through the cooling duct 21c and released to the outside to be cooled. Since it is possible to avoid a situation in which the temperature of the toner on the surface rises to a level at which filming occurs, deterioration of the image quality can be prevented.

Embodiment 5 FIG.
In each embodiment shown in FIGS. 1 to 6, each cooling duct is formed by molding or the like integrally with the housing of the image forming unit 4 using a polymer material such as plastic. However, the thermal conductivity (λ) of a polymer material such as plastic is inferior to copper or aluminum alloy. Therefore, in this embodiment, the cooling duct of each of the above embodiments is formed of a material having high thermal conductivity such as an aluminum alloy. Other configurations are the same as those of the above-described embodiments.

  When the cooling duct is formed of an aluminum alloy or the like, a method for fixing the image forming unit 4 to the casing is required. For example, a fixing means is provided on the side surface of the casing of the image forming unit 4 or the tip is formed. A cooling duct may be formed in the mold and molded together with the housing.

  In each of the above-described embodiments, the shape of the through hole in which the cooling duct is passed through the image forming unit 4 in parallel with the axial direction of the developing roller 13 and the cooling duct openings 22 are provided at both ends of the image forming unit 4. In other words, a hollow structure in which gas can flow is formed in the vicinity of the heat generating portion inside the image forming unit, thereby providing a duct function for flowing air to cool the heat generating portion. It is configured to take heat away from the periphery. However, when the material of the cooling duct is made of a material having a high thermal conductivity, the duct can be used also as a heat sink. Therefore, the cooling efficiency can be improved by increasing the surface area of the inner peripheral surface of the duct.

  Specifically, for example, by providing heat radiation fins on the inner peripheral surface of the cooling duct, the surface area of the heat sink increases, so that the cooling efficiency can be improved.

  As described above, in the image forming apparatus according to the present embodiment, the cooling duct provided in the vicinity of the heat generating portion in the image forming unit 4 is formed of a material having high thermal conductivity such as an aluminum alloy. Due to the flow, the heat generated in the image forming unit 4 can be efficiently absorbed and released to the outside, and the temperature can be prevented from rising to a level at which the toner on the surface thereof is filmed. Therefore, it is possible to prevent the deterioration of image quality.

Embodiment 6 FIG.
FIG. 7 is a longitudinal sectional view showing an image forming unit in the image forming apparatus according to the sixth embodiment of the present invention.
The difference between the present embodiment and the fourth embodiment shown in FIG. 6 and the like is that the shape of the cooling roller 23 is changed to a hollow cylindrical tube shape (roller shape) without a tip portion (projection portion). The point is that the cooling roller 23 is disposed between the cleaning unit 17 and the charging device 12 so as to contact the photoconductor 11, and the point that the cooling roller 23 is rotatably supported. Other configurations are the same as those in the fourth embodiment.

  For example, the cooling roller 23 may be configured such that a mandrel is formed of a material such as an aluminum hollow extruded material having a high thermal conductivity and the outer peripheral surface is covered with an insulating material such as a rubber thin film.

  In order to rotatably support the cooling roller 23, for example, the shaft of the cooling roller 23 is provided so as not to block the hollow opening, and both side surfaces of the image forming unit 4, an internal partition plate, an internal side wall, etc. You just need to support it. Then, since the cooling roller 23 is in contact with the photoconductor 11, it rotates in conjunction with the rotation operation of the photoconductor 11.

  In this embodiment, the cooling roller 23 is rotated by being brought into contact with the photosensitive member 11, but the cooling roller 23 may be configured to be driven by a driving means such as a gear. good.

  As described above, in the image forming apparatus of the present embodiment, the hollow cylindrical tube-shaped cooling roller 23 is brought into contact with the photosensitive member 11 to be rotatable, and the hollow opening of the cooling roller 23 is blocked. Since the image forming unit 4 is supported by both sides of the image forming unit 4 and the like, the heat radiated or conducted to the outside from the photoconductor 11 is directly absorbed by the cooling roller 23 to be efficiently absorbed and released to the outside. A large cooling effect can be obtained, and a situation where the temperature rises to a level at which the toner on the surface of the photoconductor 11 is filmed can be avoided, so that deterioration in image quality can be prevented.

Embodiment 7 FIG.
In the sixth embodiment shown in FIG. 7, the cooling roller 23 that is in contact with the photosensitive member 11 between the cleaning unit 17 and the charging device 12 is formed using aluminum and rubber. However, light is emitted from the light emitting device 18 to remove the residual potential of the photoconductor 11 to a portion between the cleaning unit 17 and the charging device 12 of the photoconductor 11, and in the configuration of the sixth embodiment, The light from the light emitting device 18 is blocked. Therefore, in the present embodiment, the cooling roller 23 of the above-described sixth embodiment is formed in a tubular shape with a transparent material such as glass that transmits light. The transparent material is an insulating material having transparency with respect to light having a wavelength that can remove the residual potential of the photoconductor 11. Other configurations are the same as those in the sixth embodiment.

  The method of fixing the image forming unit 4 to the housing when the cooling roller 23 is formed in a glass tube is the same as that of the above-described mobile phone 6 so that the shaft of the cooling roller 23 does not block the hollow opening. It may be provided and supported by both side surfaces of the image forming unit 4, an internal partition plate, an internal side wall, or the like.

  Similarly to the sixth embodiment, the driving method of the cooling roller 23 may be rotated in conjunction with the cooling roller 23 by contacting the photoconductor 11 or driven by driving means such as a gear.

  As described above, in the image forming apparatus according to the present embodiment, the cooling roller 23 having a transparent and hollow cylindrical tube shape is brought into contact with the photosensitive member 11 to be rotatable, and the hollow opening portion of the cooling roller 23 is formed. Since the image forming unit 4 is supported by both sides so as not to be blocked, the cooling roller 23 is directly supplied with heat radiated or conducted from the photoreceptor 11 to the outside without interfering with the residual potential removing action on the photoreceptor surface. It is possible to obtain a larger cooling effect by efficiently absorbing and discharging to the outside by contacting with the toner, and therefore it is possible to avoid a situation where the temperature rises to a level at which the toner on the surface of the photoreceptor 11 is filmed. Therefore, it is possible to prevent the deterioration of the image quality.

Embodiment 8 FIG.
In each embodiment shown in FIGS. 1 to 7, each cooling duct or each cooling roller is formed in a hollow tube shape (cross section is quadrangular or circular) having both ends open, and the inside of the image forming unit 4 The case where the photosensitive member 11 or the developing roller 13 is cooled in parallel by being arranged close to them in the axial direction is shown. However, since the cooling fan 10 is generally installed in the vicinity of the image fixing unit 6 as described above, the amount of air that passes through the inside of each cooling duct or each cooling roller by the airflow generated by the cooling fan 10. There are not many. Therefore, in the present embodiment, by providing the intake duct 24 between the intake side of the cooling fan 10 and the opening of the cooling duct or cooling roller closer to the cooling fan, each cooling duct or each cooling roller is provided. The amount of air passing through the interior was increased. Other configurations are the same as those of the above-described embodiments.

FIG. 8 is a perspective view showing the positional relationship among the image forming unit, the exhaust fan, the intake duct, and the inner side wall in the image forming apparatus according to the eighth embodiment of the present invention. FIG. 9 is a perspective view of the configuration of FIG. 8 as seen from the inside.
In the present embodiment, as shown in FIGS. 8 and 9, one side end portion of the image forming unit 4 is supported by the inner side wall 26 of the image forming apparatus. An intake duct opening 25 is provided in the inner side wall 26 at a position facing the cooling duct opening 22 provided at one side end of the image forming unit 4. A pipe-shaped intake duct 24 is provided connecting the intake duct opening 25 of the inner side wall 26 and the intake side of the cooling fan 10. In other words, the intake duct 24 can have one opening end opposed to the cooling duct opening 22 provided at one side end of the image forming unit 4, and the other open end can be the intake side of the cooling fan 10. Are formed in a duct shape, and one opening thereof is fixed to the intake duct opening 25 of the inner side wall 26. Other configurations are the same as those of the above-described embodiments.

  Accordingly, the intake duct 24 is provided so as to connect one of the openings at both ends of the cooling duct provided in the image forming unit 4 and the intake side surface of the cooling fan 10, and one of the openings is connected to one of the openings. The other end surface opening 25 faces the intake side surface of the cooling fan 10. The same applies when cooling with a cooling roller instead of the cooling duct.

  By providing the intake duct 24, it is possible to intake a considerable amount of air from the cooling duct opening 22 of the image forming unit 4 among the air that is sucked from the inside of the image forming apparatus by the cooling fan 10 and discharged to the outside. become.

  As described above, in the present embodiment, since the intake duct 24 is provided in order to effectively use the air flow generated by the cooling fan 10 of the image forming apparatus, a large amount of air outside the image forming unit 4 is cooled by the cooling duct. Alternatively, the inside of the cooling roller can be passed, and the inside of the image forming unit, in particular, the surface of the photoconductor 11 and the developing roller 13 can be forcibly cooled (air-cooled). Many cooling effects can be obtained.

  In each of the above-described embodiments, the printer apparatus is used as the image forming apparatus of the present invention. However, the present invention is not limited thereto, and, for example, a FAX apparatus and a copier that are similarly printed using an electrophotographic method using a developer. Alternatively, the present invention can be implemented even in the case of a composite apparatus having the functions of the various apparatuses described above in a decoding manner.

1 is a longitudinal sectional view showing an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing an image forming unit in the image forming apparatus of FIG. 1. FIG. 3 is a perspective view of the image forming unit in FIG. 2. FIG. 6 is a longitudinal sectional view showing an image forming unit in an image forming apparatus according to a second embodiment of the present invention. It is a longitudinal cross-sectional view which shows the image forming unit in the image forming apparatus of Embodiment 3 of this invention. It is a longitudinal cross-sectional view which shows the image forming unit in the image forming apparatus of Embodiment 4 of this invention. It is a longitudinal cross-sectional view which shows the image forming unit in the image forming apparatus of Embodiment 6 of this invention. FIG. 20 is a perspective view showing a positional relationship among an image forming unit, an exhaust fan, an intake duct, and an inner side wall in an image forming apparatus according to an eighth embodiment of the present invention. It is a perspective view at the time of seeing the structure of FIG. 8 from the inner side further.

Explanation of symbols

1 paper feed unit,
2 paper cassettes,
3 Print timing adjustment section,
4 Image forming unit,
5 Transfer unit,
6 image fixing means,
7 Medium carry-out conveyance path,
8 discharge roller pair,
9 Medium discharge part,
10 Cooling fan,
11 photoconductor,
12 charging device,
13 Development roller,
14 supply roller,
15 Development blade,
16 sealing material,
17 Cleaning means,
18 light emitting device,
19 Developer cartridge,
20 stirring device,
21, 21a, 21b, 21c cooling duct,
22 cooling duct opening,
23 cooling roller,
24 intake duct,
25 intake duct opening,
26 Internal sidewall of the printer,
121-124 Tip.

Claims (12)

A photoreceptor used in a developing portion of an electrophotographic image forming apparatus;
A charging device for applying a uniform potential to the surface of the photoreceptor;
A developing roller for attaching a developer to the electrostatic latent image written on the charged photoreceptor;
A supply roller for supplying a developer to the developing roller;
A developing blade for regulating the layer thickness of the developer on the developing roller;
In an image forming unit comprising a cleaning means for removing the developer remaining after transfer to a recording medium from the surface of the photoreceptor,
An image forming unit, characterized in that a hollow structure portion is provided that passes through the image forming unit in parallel with the axial direction of the developing roller and has openings at both ends of the image forming unit and is hollow inside. . The hollow structure portion is positioned in the vicinity of a first nip portion between the developing roller and the photoconductor, and is configured to have a cross-sectional shape having a pointed portion protruding toward the first nip portion. The image forming unit according to claim 1, wherein: The hollow structure portion is positioned in the vicinity of a second nip portion between the developing roller and the supply roller, and is configured to have a cross-sectional shape having a pointed portion protruding toward the second nip portion. The image forming unit according to claim 1, wherein: The hollow structure portion is positioned in the vicinity of a first contact portion where the developing blade contacts the developing roller, and has a cross-sectional shape having a pointed portion protruding toward the first contact portion. The image forming unit according to claim 1, further comprising an image forming unit. The hollow structure portion is positioned in the vicinity of a second contact portion where the cleaning unit contacts the photoconductor, and has a cross-sectional shape having a pointed portion protruding toward the second contact portion. The image forming unit according to claim 1, further comprising an image forming unit. The cooling structure which has the same cross-sectional shape as the said hollow structure part, penetrates the inside of the said image forming unit similarly, and has an opening part in both ends is provided in the inside of the said hollow structure part. The image forming unit according to claim 5. The image forming unit according to claim 1, wherein the cooling duct includes an image forming unit made of a material having high thermal conductivity. A photoreceptor used in a developing portion of an electrophotographic image forming apparatus;
A charging device for applying a uniform potential to the surface of the photoreceptor;
A developing roller for attaching a developer to the electrostatic latent image written on the charged photoreceptor;
A supply roller for supplying a developer to the developing roller;
A developing blade for regulating the layer thickness of the developer on the developing roller;
In an image forming unit comprising a cleaning means for removing the developer remaining after transfer to a recording medium from the surface of the photoreceptor,
A hollow structure portion is provided that passes through the image forming unit in parallel with the axial direction of the photoconductor and has openings at both ends of the image forming unit and is hollow inside.
Inside the hollow structure portion, the image forming unit is similarly penetrated, has openings at both ends, is rotatably supported, and contacts the photoconductor between the cleaning unit and the charging device. An image forming unit comprising a cooling roller. The image forming unit according to claim 8, wherein the cooling roller has a mandrel made of a material having high thermal conductivity and a surface covered with an insulating material. The image forming unit according to claim 8, wherein the cooling roller is formed of an insulating material having transparency with respect to light having a wavelength capable of removing a residual potential of the photoconductor. An image forming apparatus comprising the image forming unit according to claim 1. An intake port that is an opening for sucking air outside the image forming apparatus;
An exhaust port that is an opening for exhausting air inside the image forming apparatus;
A cooling fan that is provided at the exhaust port and discharges internal heat together with the air in the image forming apparatus;
An air intake duct is provided so as to connect one of the cooling ducts provided in the image forming unit or the openings on both ends of the cooling roller and an air intake side surface of the cooling fan;
The air intake duct has one end face opening facing one opening of the cooling duct or the cooling roller, and the other end face opening facing the air intake side of the cooling fan. The image forming apparatus described in 1.

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