JP2000321928A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To output images speedily and continuously with an inexpensive configuration without degrading an output image quality due to temperature rising in a device main body by providing a latent-image carrier, at its axial ends, with fins disposed so as to generate an airflow while rotating accompanying the rotation of the latent-image carrier. SOLUTION: Flanges made of a cast iron is screwed to both ends of a photoreceptor drum 1 with screws freely attachably/detachably. The peripheral face of each flange is machined so as to have 128 fins in all at an interval of approximately 26.6 mm. When the photoreceptor drum 1 rotates in an A direction, an airflow V, a stream of air, is produced by the fines provided on the photoreceptor drum 1. In order to use the airflow V for cooling a developing device 4, a duct 5 is disposed between the axial end of the photoreceptor drum 1 and the developing device 4. Thus, the airflow V is efficiently conveyed to the developing device 4 and a rise in the temperature of the airflow V due to heat generated by a heat generating means is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic or electrostatic recording type image forming apparatus, comprising: a rotatable latent image carrier for carrying a latent image on a peripheral surface; And a developing device for visualizing the latent image on the latent image carrier by applying a developer.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine of an electrophotographic system, a printer, a facsimile or the like, FIG.
As shown in FIG. 1, a latent image carrier 101 such as a photosensitive drum for carrying an electrostatic latent image formed by a predetermined process.
The developer carrier 14 provided in the developing device 104
1 are arranged at a predetermined interval G1, and an appropriate developing bias voltage is applied between them by a power supply (not shown) to develop the electrostatic latent image on the latent image carrier 101.

In order to perform the above-mentioned development, a developer carrier 104 is used.
As a method of forming a developer layer having a predetermined thickness thereon, as shown in FIG. 16, a developer thin layer forming means which is a plate-like member for forming a thin layer with a developer on a developer carrier 141 is used. 14
17 in which the developer 3 is disposed at an appropriate distance G2 from the developer carrier 141, and the developer is fed into the vicinity N of the developer thin layer forming means 143 by rotation of the developer carrier 141, as shown in FIG. A method of contacting the developer carrier 141 with an appropriate pressure p by a developer thin layer forming means 143 ′, which is a plate-like member for forming a thin layer with the developer on the developer carrier 141. It is well known and is in practical use.

[0004]

However, in such a conventional image forming apparatus, when image output is continuously performed without providing an appropriate pause interval, various types of image formation, mainly, image density reduction, are performed. There is a possibility that the output image quality is reduced.

[0005] This is mainly due to the eddy current caused by the rotation of the developer carrying member having a built-in magnetic field generating means, and the friction between the developer thin layer forming means and the like and the developing agent. It is considered that the temperature inside the forming apparatus main body increased, and the quality of the developer was changed.

FIG. 18 shows a normal temperature and normal humidity (about 23 ° C., 50% R).
H or less), the temperature Tdb of the developer thin layer forming means.
And the relationship between the image reflection density and the image reflection density.

[0007] As shown in FIG. 18, it can be seen that the image reflection density decreases as the temperature Tdb increases.

[0008] Here, the image reflection density is based on MacBe
This is the average value of the values obtained by measuring five points in a portion where a circular original having a image reflection density of 1.2 and a diameter of 5 mm appeared on the copied image using an image reflection densitometer RD-914 manufactured by Th. same as below).

[0009] The above-mentioned problems are becoming more and more serious in today's world where the speed of image formation and the number of processing units are required to increase with the development of the network environment.

Certainly, a Peltier element (a device in which one side becomes low in temperature and the other side becomes high in temperature when a current is applied, and is also called a semiconductor heat pump. It is used for temperature compensation of semiconductor lasers which are severe in temperature. .), But the disadvantage is that this element is expensive.

[0011] The use of a cooling fan has the same disadvantages, and there are many restrictions on the arrangement space. Therefore,
The present invention provides an image forming apparatus capable of performing high-speed and continuous image output with an inexpensive configuration without lowering the output image quality due to a rise in temperature inside a developing device and an image forming apparatus main body including the developing device. The purpose is to provide the device.

[0012]

Means for Solving the Problems The main invention of the present application is to provide a rotatable latent image carrier for carrying a latent image on a peripheral surface thereof,
A developing device that visualizes the latent image on the latent image carrier by applying a developer to the latent image carrier, wherein the latent image carrier is rotated at an axial end thereof. And a fin arranged to generate an air flow by rotating the developing device, and the developing device is configured to be cooled by the air flow.

[0013]

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

(First Embodiment) First, a first embodiment of the present invention will be described.

FIG. 1 is a schematic sectional view showing an example of an image forming apparatus according to the first embodiment of the present invention.

In this image forming apparatus, as shown in FIG. 1, a photosensitive drum 1 as a latent image carrier on which an electrostatic latent image is formed on an outer peripheral surface and an outer peripheral surface of the photosensitive drum 1 are charged to a specified potential. Primary charging means 2, a laser scanner unit (not shown) for forming an electrostatic latent image on the outer peripheral surface charged to a prescribed potential by exposure, and visualizing the electrostatic latent image with a developer. The image forming apparatus includes a developing device 4, a transfer unit 3 that transfers a visible image (visible image) formed on the outer peripheral surface to a transfer material P that is a sheet-shaped recording medium, and a fixing unit 7.

In such an image forming apparatus, first, the laser scanner unit exposes the outer peripheral surface of the photosensitive drum 1 charged to a specified potential by the primary charging means 2 so that the image forming apparatus is externally exposed. Is formed on the outer peripheral surface according to the image information given to the image forming apparatus.

Next, the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 1 is visualized as a visible image by applying a developer from the developing device 4.

On the other hand, the transfer material P on which the image information corresponding to the given image information is recorded is provided on a cassette (not shown) removably supported by the main body of the image forming apparatus or one of the image forming apparatuses. Paper is fed from a multi-paper tray (not shown) arranged at a predetermined timing or the like to a transfer nip formed between the photosensitive drum 1 and the transfer means 3.

Therefore, the recording paper P which has reached the transfer nip is formed on the outer peripheral surface of the photosensitive drum 1, and the carried visual image is transferred from the transfer means 3 by electrical interaction. Is separated from the photosensitive drum 1.

Next, the transfer material P having the developed image carried on one surface in an unfixed state (hereinafter, the developed image in the unfixed state is referred to as an unfixed image) is supplied to the fixing means 7 by heat supply. By applying pressure, the unfixed image is melted and fixed, so that the transfer material P records an image corresponding to the given image information, and the image-formed transfer material P The paper is discharged onto a paper discharge tray (not shown) arranged on the other side of the main body of the apparatus.

As shown in FIG. 2, the developing device 4 has a toner container 41 for storing a developer and a sleeve 42 for carrying the developer.

The sleeve 42 is a hollow cylinder made of an aluminum alloy A6063 having a diameter of 32.3 mm and a length of 325 mm, and is provided with a clutch and a gear (not shown) by a motor (not shown) provided in the main body of the image forming apparatus. ) And the like, and is rotationally driven in the A direction at a speed of 868.5 mm / sec.

The surface of the sleeve 42 has a layer having an initial thickness of 10 to 14 μm obtained by dispersing conductive particles such as carbon graphite in a resin such as phenol after blasting by spraying spherical glass particles. The center line average roughness is 0.40 to 0.60 due to sanding and the like.
μmRa.

A hollow flange 4 (not shown) made of aluminum alloy A2011 is press-fitted into both ends of the sleeve 42 in the axial direction.

The distance G1 between the sleeve 42 and the photosensitive drum 1
Is 160-200 μm by a spacer roller (not shown).
m, and between the two, as shown in FIG.
pp = 900-1100V, frequency f = 1 / T = 265
0 to 2750 Hz (a rectangular wave AC voltage having a duty ratio η = 0.4 is a DC voltage Vdc variable between 0 and 600 V)
Are superimposed and applied.

Here, the duty ratio η is Tdev /
This is a value obtained as T.

Inside the sleeve 42, a ferrite magnet roller 46 is fixedly provided as a means for generating a magnetic field.

On the surface of the magnet roller 46, a total of six magnetic poles such as a developer pumping pole S3 and a developing pole N2 are provided.

The sleeve 4 is formed by the developer pumping pole S3 or the like.
The developer sucked on the surface 2 is thinned by the interaction between the SPCC rectangular doctor blade 43 having a thickness of 1 mm and the developer layer pressure regulating pole N1, which is disposed on the sleeve 42 while maintaining the gap G2. Stratified.

In this embodiment, the interval G2 is 21
0 to 250 μm.

The average charge amount of the developer on the sleeve 42 at normal temperature and normal humidity is +8 to +12 μC / g, and the coating amount is 0.7 to
0.9 mg / cm ² .

The developer contains a styrene acrylic binder resin, magnetite as a magnetic material, silica as a fluidizing agent, and strontium oxide as an abrasive, and has an initial weight average particle size of 7.5 to 7.5. It is 8.0 μm.

The photosensitive drum 1 has a diameter of 108 mm and a length of 3 mm.
The peripheral speed of the photosensitive drum 1, that is, the process speed is 450 mm / sec.
It is.

FIG. 4 is a cross-sectional view showing the structure of the cylinder portion forming the peripheral surface of the photosensitive drum 1.

As shown in FIG. 4, a cylinder 11 which forms a peripheral surface of the photosensitive drum 1 includes a conductive support 112 made of pure aluminum, and a photosensitive layer sequentially stacked on the surface of the conductive support 112. 111 (the charge injection blocking layer 111a and the photoconductive layer 111b exhibiting photoconductivity) and the surface layer 113, and the maximum thickness thereof is 5 mm.

Here, the charge injection blocking layer 111a is for preventing charge injection from the conductive support 112 to the photoconductive layer 111b, and is provided as necessary.

The photoconductive layer 111b is made of an amorphous material containing at least silicon atoms and exhibits photoconductivity.

Further, the surface layer 13 contains silicon atoms and carbon atoms (and, if necessary, hydrogen atoms or halogen atoms or both atoms), and has a function of maintaining a visible image in an electrophotographic image forming apparatus. Have.

As shown in FIG. 5, flanges 15f and 15r made of cast iron are detachably screwed to both ends of the cylinder portion 11.

The reason why the flanges 15f and 15r are made detachable is to consider the replacement of the heat generating means 16 and the like provided in the hollow portion to prevent so-called image deletion.

The heat generated by the heat generating means 16 is applied to the contact surfaces between the flanges 15f, 15r and the cylinder portion 11 and the center of the flanges 15f, 15r.
In order to prevent the temperature of the cylinder portion 11 from being lowered by escaping to the position r, rubber packings 17f and 17r having a thickness of 0.5 mm are inserted as heat insulating members.

The outer peripheral surfaces of the flanges 15f and 15r are shown in FIG.
As shown in the figure, the fins are machined to have a total of 128 fins 14 at intervals of about 26.6 mm.

As shown in FIG. 7, the height H of the fin 14 is
Is 10 mm from the outer peripheral surface of the photosensitive drum 1, and the thickness of the fin 14 is T1 = 0.5 mm at the tip and T2 at the base.
= 1 mm and width is 10 mm.

The photosensitive drum 1 rotates in the direction A shown in FIG.
As a result, an airflow V as an airflow is generated.

In order to use the air flow V for cooling the developing device 4, a duct 5 is provided between the axial end of the photosensitive drum 1 and the developing device 4, as shown in FIG. Thus, the air flow V is efficiently transported to the developing device 4 and the temperature of the air flow is prevented from rising due to the heat generated by the heat generating means 16.

The duct 5 is made of resin. As shown in FIGS. 8 and 9, when viewed from the axial direction of the photosensitive drum 1, the duct 5 has a portion 5c having an arc shape, a portion 5s having a linear shape, a discharge portion 5e, and the like. In other words, when viewed from the vertically upward Y direction, it has a substantially T-shape and is symmetrical with respect to the line L.

When viewed from the axial direction X of the photosensitive drum 1,
As shown in FIG. 2, the portion 5 c having an arc shape has a central angle 23 along the rotation direction A of the photosensitive drum 1 from the horizontal line H.
It is formed over a range of a central angle of 72 ° from the position of °.

The upper part 5su of the linear part 5s
Are formed to extend from the horizontal line H along the rotation direction A of the photosensitive drum at a central angle of 95 ° (= 23 ° + 72 °) to the developer layer thickness regulating member 43 provided in the developing device 4.

The lower part 5sl of the linear part 5s
Are formed to extend from the horizontal line H along the rotation direction A of the photosensitive drum at a central angle of 95 ° (= 23 ° + 72 °) to the developer layer thickness regulating member 43 provided in the developing device 4.

A rubber packing is provided around the rectangular opening 5a, which is a contact portion of the duct 5 with the developer layer thickness regulating member 43, to prevent the air flow V from leaking.

As shown in FIG. 9, the duct 5 is fixed to the rotating shaft of the photosensitive drum 1 by supporting portions 5hf and 5hr at both ends in the axial direction of the photosensitive drum 1.

As described above, the fin 14 and the duct 5 provided at the end of the photosensitive drum 1 in the axial direction are connected to the sleeve 43 provided in the developing device 4 by the air flow V that has come into contact with the developer layer thickness regulating member 43. By removing the heat generated by the rotation of the developing device 4, the temperature rise of the developing device 4 can be suppressed.

Table 1 shows the relative values of the image density transition and the apparatus cost when a standard density original was continuously copied and printed at a speed of 85 sheets / minute on one side of an A4 size transfer material at normal temperature and normal humidity. It is shown.

[0055]

[Table 1] Here, Comparative Example 1 relates to an image forming apparatus having the same configuration as the image forming apparatus according to the first embodiment except that the fin 14 and the duct 5 as described in the first embodiment are not provided. Things.

According to Table 1, the superiority of the image forming apparatus according to this embodiment can be understood.

(Second Embodiment) Next, an image forming apparatus according to a second embodiment of the present invention will be described. still,
The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The biggest difference between the image forming apparatus according to the present embodiment and the image forming apparatus according to the first embodiment is that the latent image carrier has a belt shape.

As shown in FIG. 10, the belt-like latent image carrier 1 'used in the present embodiment has a belt portion 11' forming a peripheral surface having a thickness 2 formed by electroforming.
A thickness of 0.01 μm on the surface of the 0 μm nickel thin film 111 ′.
It is formed by forming a photosensitive layer 111 ′ and a surface layer 113 ′ similar to those of the first embodiment on the surface of a deposited film 112 ′ of aluminum having a thickness of about 0.2 μm.

The belt portion 11 'has a peripheral surface having a total length of 350.
mm and a width of 360 mm, as shown in FIG. 11, two driven rollers made of A6063 (diameter 20 mm) 18a,
18b, the A6063 drive roller 19
(Diameter 20 mm) while the peripheral surface is 45
It is driven in the direction A at a speed of 0 mm / s.

In the present embodiment, as shown in FIG. 12, a total of eight fins 19f and 18bf are arranged at an interval of about 7.9 mm on the outer peripheral surfaces of the ends of the driving roller 19 and the driven roller 18b. ing.

As shown in FIG. 13, the fins 19f, 18
The height H of bf is 8 mm from the peripheral surface of the belt portion 11 ′.
It is.

The thickness of each of the fins 14 is T1 =
0.5 mm, T2 = 1 mm at the base, and width W is 10
mm.

The duct 5 ′ is made of resin,
When viewed from the direction of the rotation axis such as 9 as shown in FIG.
It has a substantially Y shape, and is disposed between the fins 19f and 18bf and the developing device 4 as in the first embodiment.

Since the structure of the other duct 5 'is the same as that of the duct 5, a detailed description is omitted.

Heat generation means 16 for preventing image deletion
As shown in FIG. 11, a, 16b, and 16c are separately arranged in three.

A cover (not shown) of the same shape is attached to a substantially triangular front opening formed by the photosensitive belt 11.

Structures other than those described above are the same as those of the image forming apparatus according to the first embodiment. As can be seen from the above, when a belt is used as a photoreceptor, the configuration tends to be slightly more complicated than when a drum is used.

According to Table 1, the performance is slightly inferior to the image forming apparatus according to the first embodiment and the cost is slightly higher, but the image forming apparatus according to the present embodiment in comparison with Comparative Example 2 Understand the superiority of

However, the image forming apparatus according to the present embodiment has a higher degree of freedom in designing the image forming apparatus than the image forming apparatus according to the first embodiment.

Here, the comparative example 2 refers to the fins 19f, 1
The present invention relates to an image forming apparatus having the same configuration as the image forming apparatus according to the second embodiment except that the image forming apparatus does not include the 8bf and the duct 5.

(Third to thirty-second embodiments) Next, third to thirty-second embodiments will be described. Note that the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the image forming apparatus according to the third to thirty-second embodiments, the peripheral speed or diameter of the latent image carrier provided in the image forming apparatus is different from that of the first embodiment. The configuration is the same as that of the first embodiment except that the peripheral speed or the diameter of the latent image carrier is different.

First, the effect on the moving speed (peripheral speed) of the peripheral surface of the latent image carrier in the present invention will be described.

FIG. 14 shows the moving speed (peripheral speed) Vprs of the peripheral surface of the latent image carrier of the first embodiment, the third embodiment to the sixteenth embodiment, and the comparative examples 3 to 16. It shows the relationship with the image reflection density RD.

Here, the image reflection density RD is continuous 2000
This is the value after the sheet is output (the same applies hereinafter).

In FIG. 14, j3 to j16 indicate the third to sixteenth embodiments, respectively, and h3 to h16
16 shows Comparative Examples 3 to 16 respectively.

Here, the image forming apparatuses according to the third to ninth embodiments have a relation of Vslv = 600 mm / s
The configuration is the same as that of the image forming apparatus according to the first embodiment except that the latent image carrier rotates at Vprs shown on the horizontal axis in FIG.

Further, the image forming apparatuses according to Comparative Examples 3 to 9 do not have fins and ducts, and
The configuration is the same as that of the image forming apparatus according to the first embodiment, except that slv = 600 mm / s and the latent image carrier rotates at Vprs shown on the horizontal axis in FIG. is there.

In the image forming apparatus according to the tenth to sixteenth embodiments, Vslv = 1000 mm / s, and the latent image carrier rotates at Vprs shown on the horizontal axis in FIG. The configuration is the same as that of the image forming apparatus according to the first embodiment except for the configuration.

The image forming apparatuses according to Comparative Examples 9 to 15 do not have fins and ducts, and
Vslv = 1000 mm / s, and FIG.
The configuration is the same as that of the image forming apparatus according to the first embodiment except that the latent image carrier rotates at Vprs indicated by the horizontal axis.

According to FIG. 14, the performance of the image forming apparatus according to the embodiment of the present invention is always superior to the performance of the image forming apparatus according to the comparative example, and Vprs = 30.
It is understood that the cooling effect is reduced when the speed is less than 0 mm / sec.

It is considered that this is because the speed of the generated air flow is not sufficient because the moving speed of the fins is reduced.

Next, the effect of the diameter of the latent image carrier in the present invention will be described.

FIG. 15 shows the first embodiment, the seventeenth embodiment to the thirty-second embodiment, and the comparative examples 17 to 3.
2 shows the relationship between the diameter φdr of the latent image carrier 2 and the image reflection density RD.

In FIG. 15, j17 to j32 denote the seventeenth to thirty-second embodiments, respectively.
17 to h32 indicate Comparative Examples 16 to 32, respectively.

Here, the image forming apparatus according to the seventeenth embodiment to the twenty-fourth embodiment has Vslv = 600 m
The configuration of the image forming apparatus according to the first embodiment is the same as that of the image forming apparatus according to the first embodiment, except that the latent image carrier is formed at m / s and φdr shown on the horizontal axis in FIG.

The image forming apparatuses according to Comparative Examples 17 to 24 do not have fins and ducts,
lv = 600 mm / s, and φ shown on the horizontal axis in FIG.
The configuration is the same as that of the image forming apparatus according to the first embodiment except that the latent image carrier is formed by dr.

The image forming apparatus according to the twenty-fifth embodiment to the thirty-second embodiment has a configuration in which Vslv = 1000 mm /
s, which is the same as the configuration of the image forming apparatus according to the first embodiment, except that the latent image carrier is formed at φdr shown on the horizontal axis in FIG.

The image forming apparatuses according to Comparative Examples 25 to 32 do not have fins and ducts, and
= 1000 mm / s and φd shown on the horizontal axis in FIG.
The configuration is the same as that of the image forming apparatus according to the first embodiment except that the latent image carrier is formed at r.

According to FIG. 15, the performance of the image forming apparatus according to the embodiment of the present invention is always superior to the performance of the image forming apparatus according to the comparative example, and φdr = 100.
It can be seen that when the diameter is less than mm, the cooling effect is reduced.

This is considered to be because the number of fins that can be arranged is reduced, and the speed of the generated air flow is not sufficient.

However, from the viewpoint of a small installation area required for the image forming apparatus, it is not necessary to increase φdr infinitely.
20 mm or less, 18 in a full-color image forming apparatus
0 mm or less is desirable.

As described above, the embodiments of the present invention using the magnetic one-component developer have been described, but the technical scope of the present invention is not limited to these embodiments.

For example, a developing means having two or more developer carriers on one latent image carrier, a developing means of a type in contact with the developer carrier as developer regulating means, not only the developer carrier but also the developing means All the changes recognized as small changes in the light of the gist of the present invention are within the technical scope of the present invention, such as the developing means in which the magnetic field generating means included in the agent carrier rotates together, in other words, in view of the gist of the present invention. .

Further, a developing device having two or more developer carrying members, a developing device having a columnar or cylindrical developer layer forming means, a developing device using a two-component developer containing a toner and a carrier, etc. The present invention is also applicable to an image forming apparatus including

Further, as a material of the developer carrying member, stainless steel may be used, or an elastic layer such as rubber may be provided on a surface layer of aluminum alloy or stainless steel.

Further, an organic photoreceptor (OPC) can be used as the photosensitive layer of the latent image carrier.

[0099]

As described above, according to the present invention according to the present application, the output image quality is not deteriorated due to the temperature rise inside the developing device and the image forming apparatus main body including the developing device. With an inexpensive configuration, image output can be performed at high speed and continuously.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a latent image carrier and a developing device provided in the image forming apparatus of FIG. 1;

FIG. 3 is a waveform diagram of a developing bias applied between a latent image carrier and a developer carrier in the image forming apparatus shown in FIG.

FIG. 4 is an enlarged cross-sectional view of a cylinder portion surface of a latent image carrier provided in the image forming apparatus of FIG.

FIG. 5 is a sectional view of a latent image carrier provided in the image forming apparatus of FIG. 1;

FIG. 6 is an enlarged sectional view of an axial end of a latent image carrier provided in the image forming apparatus of FIG. 1;

7 is an enlarged perspective view of a fin provided at an end in the axial direction of the latent image carrier shown in FIG. 6;

FIG. 8 is an elevational view of the latent image carrier and the developing device shown in FIG. 2;

9 is a perspective view showing a schematic configuration of a duct for guiding an airflow by a fin provided at an axial end of the latent image carrier shown in FIG. 6 to a developing device.

FIG. 10 is an enlarged sectional view of a surface of a photosensitive belt serving as a latent image carrier provided in an image forming apparatus according to a second embodiment of the present invention.

FIG. 11 is a schematic configuration diagram of a main part of an image forming apparatus according to a second embodiment of the present invention.

FIG. 12 is an enlarged cross-sectional view of a supporting roller and a driving roller of a photosensitive belt as a latent image carrier provided in the image forming apparatus shown in FIG.

FIG. 13 is an enlarged perspective view of fins provided at axial ends of the support roller and the drive roller shown in FIG.

FIG. 14 is a diagram illustrating a relationship between a moving speed of a peripheral surface of a latent image carrier and an image reflection density of an output image in the image forming apparatus according to the embodiment of the present invention.

FIG. 15 is a diagram illustrating a relationship between a diameter of a photosensitive drum as a latent image carrier and an image reflection density of an output image in the image forming apparatus according to the embodiment of the present invention.

FIG. 16 is a schematic configuration diagram of a latent image carrier and a developing device provided in a conventional image forming apparatus.

FIG. 17 is a schematic configuration diagram of a latent image carrier and a developing device provided in a conventional image forming apparatus.

FIG. 18 is a diagram illustrating a relationship between a temperature of a developing device and an image reflection density of an output image.

[Explanation of symbols]

 Reference Signs List 1 latent image carrier 4 developing device 14 fin 19f fin 18bf fin

Claims (4)

[Claims] 1. A latent image carrier that carries a latent image on a peripheral surface thereof, and a developing device that visualizes the latent image on the latent image carrier by applying a developer to the latent image carrier. In the image forming apparatus, the latent image carrier has fins disposed at an axial end thereof so as to generate an airflow by rotating with the rotation of the latent image carrier, and the developing device is cooled by the airflow. An image forming apparatus having the following configuration. 2. The image forming apparatus according to claim 1, wherein the latent image carrier is formed in a hollow cylindrical shape. 3. The image forming apparatus according to claim 1, wherein the peripheral speed of the latent image carrier is 300 mm / sec or more. 4. The image forming apparatus according to claim 2, wherein the latent image carrier has a diameter of 100 mm or more.