JP2001066892A - Developing device and image forming device equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the image density from lowering due to the temperature rise of developer in a developing device even in the case of consecutively outputting an image at a high speed in spite of a developing device whose cost rising is restrained to be small. SOLUTION: A 4th developer stirring and carrying member 48 is arranged near a developing sleeve 42 in a developer storing member 41. The member 48 is constituted by bending a copper round bar. A rotary supporting shaft 48b on a front side projected from a main body 48a pierces a front side wall 41f and is projected to the outside. A flat part 48c is formed as a heat radiation part at the projected part. By crushing the projected part of the shaft 48b by extending work or the like, the flat part 48c is formed so that its cross section may be a flat rectangle. Since the surface area of the flat part 48c is increased, heat flowing from the main body 48a is efficiently radiated to the open air at the flat part 48c through the copper round bar having high heat conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for applying toner to an electrostatic latent image formed on an image carrier and developing it as a toner image, and an image forming apparatus having the same.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, for example, a copying machine, a printer, a facsimile, and the like,
An electrostatic latent image is formed on a photosensitive drum (image carrier) by charging and exposure, and the electrostatic latent image is developed by a developing device. The developing device has a rotatable developing sleeve that is arranged to face the photosensitive drum. The developing sleeve carries a thin layer of developer on its surface and delivers it to a developing position facing the photosensitive drum. A developing bias voltage is applied to the developing sleeve, whereby toner is attached to the electrostatic latent image and developed as a toner image.

In the above-described developing device, as a method of carrying a thin layer of the developer on the surface of the developing sleeve (a method of forming a developer layer), as shown in FIG. 26, a plate-like member (developer layer forming means) is used. There is known a method of bringing the developing sleeve 43 into contact with the developing sleeve 42 at an appropriate pressure p. Alternatively,
As shown in FIG. 27, the plate member 43 is
2 and an appropriate distance G2 from the developing sleeve 42.
Is rotated in the direction of arrow R42 so that the developer is
Has been widely performed.

The developer replenished from the developer replenishing device 5 is supplied to a ladder-like or blade-like developer stirring and conveying member 4.
By rotating 6, 47, the toner is conveyed toward the developing sleeve 42 while stirring.

[0005]

However, in the conventional developing device described above, when image output is continuously performed without providing an appropriate pause interval, various output image quality deteriorations, mainly image density reductions, occur. There was a problem of inviting.

The main cause of this is that the developing sleeve 4 when the magnet roller (magnetic field generating means) 44 is built in
Due to the eddy current due to the rotation of 2 and the frictional heat with the developer,
It is considered that the rise in the temperature near the developing device causes deterioration of the developer mainly composed of resin.

FIG. 28 shows the relationship between the temperature T _bld of the plate member 43 of the developing device 4 and the image reflection density at normal temperature and normal humidity (temperature about 23 ° C., humidity 50%). From the figure,
Conversely, when the temperature T _bld rises, the maximum image reflection density RD _max
It can be seen that is decreasing.

Here, the maximum image reflection density RD _max is
This is the average of the values measured at five points where a circular original having a reflection density of 1.2 mm and a diameter of 5 mm appeared on the copied image using an image reflection densitometer RD-914 manufactured by MacBeth, USA. (same as below).

[0009] The above-mentioned problem of a decrease in image density is becoming more and more serious in today's world, which requires an increase in image output speed and an increase in the number of processing units accompanying the development of a network environment.

[0010] As a countermeasure, for example, a Peltier element (a device in which one side becomes low temperature and one side becomes high temperature when an electric current is applied, also called a semiconductor heat pump. It is used for temperature compensation of a temperature-sensitive semiconductor laser or the like. ) Can be used, but this element is disadvantageous in that it is expensive.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and while suppressing an increase in cost, even when image output is performed at high speed and continuously, the developer in the developing device can be used. It is an object of the present invention to provide a developing device capable of preventing a decrease in image density due to a rise in temperature of an image forming apparatus and an image forming apparatus provided with the developing device.

[0012]

According to a first aspect of the present invention, there is provided a developer stirring and conveying means for stirring and conveying a powder developer stored in a developer storing member. A developer carrying member that carries and transports the developer on the surface thereof, and a developer layer thickness regulating member that regulates a layer thickness of the developer carried on the surface of the developer carrying member. In a developing device that conveys the regulated developer to a developing position opposite to the surface of the image carrier on the surface of the developer carrier and performs development, the developer stirring and conveying unit is rotated by the developer accommodating member. At least one developer stirring / conveying member which is freely supported and stirs / conveys the developer in the developer accommodating member, wherein at least one of the developer stirring / conveying members includes the developer accommodating member Heat radiating part projected outside the member A, wherein the.

According to a second aspect of the present invention, in the developing device according to the first aspect, when the developer stirring and conveying means has a plurality of the developer stirring and conveying members, the developer stirring and conveying member is closest to the developer layer thickness regulating member. The developer agitating and conveying member having the heat radiating portion is disposed at a position higher than the uppermost part of the developer carrying member.

According to a third aspect of the present invention, in the developing device of the first or second aspect, the heat radiating portion is provided on a rotation support shaft rotatably supported by the developer accommodating member. Features.

According to a fourth aspect of the present invention, in the developing device according to the third aspect, regarding the circumferential length of the longitudinal section in a direction orthogonal to the rotation support shaft, the circumference of the heat radiating portion is equal to the circumference of the rotation support shaft. It is longer than the circumference.

According to a fifth aspect of the present invention, in the developing device of the fourth aspect, the heat radiating portion is a flat portion formed by crushing the rotation support shaft.

According to a sixth aspect of the present invention, in the developing device of the fourth aspect, the radiator is a fin attached to the rotation support shaft.

The present invention according to claim 7 is based on claims 1, 2,
In the developing device of 3, 4, 5, or 6, a developer scattering prevention member that covers a portion of the surface of the developer carrier that is located between the developer layer thickness regulating member and the image carrier is provided. Having.

According to an eighth aspect of the present invention, in the developing device of the seventh aspect, the developer scattering preventing member is formed of a material mainly containing aluminum, copper, or zinc. .

According to a ninth aspect of the present invention, there is provided an electrostatic latent image forming means for forming an electrostatic latent image on the surface of an image carrier, and a developing means for adhering toner to the electrostatic latent image and developing it as a toner image. And a transfer unit for transferring the toner image on the image carrier to a transfer material, wherein the developing unit comprises: (3) The developing device described in (1).

According to a tenth aspect of the present invention, in the image forming apparatus of the ninth aspect, the image carrier has a heating means inside.

[0022]

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

<Embodiment 1> FIG. 1 shows an example of a developing device according to the present invention. FIG. 1 is a longitudinal sectional view showing a schematic configuration of the developing device.

In FIG. 1, reference numeral 1 denotes an image carrier rotatably supported in the direction of arrow R1, and reference numeral 2 denotes a charging roller as charging means for uniformly charging the surface of the photosensitive drum 1 to a predetermined polarity and potential. Exposure means 3 is an electrostatic latent image forming means for exposing the charged image carrier surface to form an electrostatic latent image. In addition, the image carrier 1, a charging roller (charging means)
2. Exposure means (electrostatic latent image forming means) 3, developing device (developing means) 4 described later, transfer means for transferring the toner image formed on the surface of image carrier 1 by developing device 4 to a transfer material such as paper. (Not shown) constitutes an image forming apparatus (not shown).

In the developing device 4 shown in FIG. 1, a developer replenishing device 5 is provided at the upper right of the developing device 4. Each of the developing device 4 and the developer replenishing device 5 is formed to be long along the axial direction (the front and back direction in FIG. 1) of a drum-shaped electrophotographic photosensitive member (hereinafter, referred to as “photosensitive drum”) 1 as an image carrier. Have been. The developer replenishing device 5 has a first developer replenisher 51 disposed at an upper part and a second developer replenisher 52 disposed at a lower part. The developer discharged from the rear side of the first developer replenisher 51 falls to the rear side of the second developer replenisher 52, and the elliptical shape disposed in the second developer replenisher 52. Is uniformed in the longitudinal direction.

The developer, which has been made uniform in the longitudinal direction, is then rotated by a permanent magnet roller 52b disposed at the lower bottom of the second developer replenisher 52 to thereby lower the same at the lower bottom of the second developer replenisher 52. Is discharged from the substantially rectangular gap 52c disposed in the developer stirring chamber 41a. The developer stirring chamber 41a is located at the uppermost stream among the three developer stirring chambers 41a, 41b, and 41c of the developer accommodating member 41 of the developing device 4. Next, the developer is conveyed while being stirred by the first developer stirring and conveying member 45, and is conveyed to the developer stirring chamber 41b on the downstream side. Then the developer
The toner is conveyed while being stirred by the second developer stirring and conveying member 46, and is conveyed to the most downstream developer stirring 41c. Next, the developer is conveyed while being stirred by the third developer stirring and conveying member 47, and reaches the developing sleeve 42 as a developer carrying means. As shown in FIG. 2, the first, second, and third developer stirring and conveying members 45, 46, and 47 are ladder-like members made of resin, and have the same shape and the same number of rotations.

The developing sleeve 42, which is a developer carrier,
Aluminum alloy A 32.28mm in diameter and 325mm in length
6063 is a hollow cylindrical member mainly formed by a motor (not shown) disposed in an image forming apparatus main body (not shown) through a clutch, a gear, etc. (neither is shown) in the direction of arrow R42. At a speed of 868.5 mm / sec. Outer surface (outer peripheral surface) of developing sleeve 42
Has a layer having an initial thickness of 10 to 14 μm formed by dispersing conductive particles such as carbon graphite in a resin such as phenol after spraying spherical glass particles, and has a center line average roughness of the outer surface. The thickness is set to 0.40 to 0.60 μmRa by sanding or the like.

As shown in FIG. 3, a hollow flange 42 made of aluminum alloy A2011 is provided at both axial ends (both longitudinal ends) of a sleeve body 42a of the developing sleeve 42.
As shown in FIG. 5, a magnet roller (roller-shaped permanent magnet) 44 having a diameter of 29 to 30 mm is fixedly disposed inside the developing sleeve 42. On the surface of the magnet roller 44, a total of six magnetic poles S1, S2, S3, N1,
N2 and N3 are provided, and these magnetic poles have a function of attracting magnetic toner.

The gap G2 = 2 from the surface of the developing sleeve 42
A plate-like member 43 as a developer layer thickness regulating member made of SPCC is disposed with a thickness of 00 to 240 μm. As shown in FIG. 4, the plate member 43 has a trapezoidal cross section, a thickness of 0.3 mm at the distal end 43a, and a thickness of 0.3 mm at the proximal end 43b.
Is 1.6 mm. Since the cross-section is trapezoidal, the concentration of the lines of magnetic force on the leading end 43a by the magnet roller 44 is generated as compared with a rectangular cross-section, and a strong developer regulation performance can be exhibited.

As shown in FIG. 5, the developer absorbed on the surface of the developing sleeve 42 by the action of the magnetic pole S3 for picking up the developer and the like is applied to the plate member 43 and the magnetic pole N for regulating the thickness of the developer layer.
Due to the interaction with 1, the toner is thinned while being triboelectrically charged and is carried on the surface of the developing sleeve.

A developing bias is applied between the developing sleeve 42 and the photosensitive drum 1 by a developing bias applying power source 40. As a result, the toner carried on the surface of the developing sleeve 42 is attached to the electrostatic latent image on the surface of the photosensitive drum 1 and development is performed.

A developer scattering prevention cover (developer scattering prevention member) 74 is screwed to the plate-like member 43 to prevent the developer from scattering due to the centrifugal force of the rotation of the developing sleeve 42. Foreign matter is prevented from adhering to the surface of the developing sleeve 42. Developer scattering prevention cover 74
Is formed of a material mainly containing aluminum, copper, or zinc, and of the surface of the developing sleeve 42,
The portion located between the developer layer thickness regulating member 43 and the photosensitive drum 1 is covered.

Since the developer t2 not applied to the surface of the developing sleeve 42 moves to the rear face F of the plate member 43, the rear face F has a fourth developer stirring and conveying member rotating in the direction of arrow R48. 48 are provided. This allows
This prevents the developer t2 from causing a toner parking phenomenon (a state in which the toner does not behave as a powder as a result of excessive compression of the toner) on the back surface portion F.

In the present embodiment, the fourth developer agitating / conveying member 48 is a first developer agitating / conveying means constituting a developer agitating / conveying means.
Of the fourth to fourth developer stirring and conveying members 45, 46, 47, and 48, they are arranged at positions closest to the developer layer thickness regulating member 43 and higher than the uppermost part of the developing sleeve 42. .

As shown in FIG. 6, the fourth developer stirring / conveying member 48 includes first, second, and third developer stirring / conveying members 4.
5, 46 and 47 have different shapes. The fourth developer stirring and conveying member 48 is configured by bending a copper round bar having a circular cross section with a diameter of 1.5 mm as shown in FIG. The rotation speed of the fourth developer stirring and conveying member 48 is
First, second, and third developer stirring and conveying members 45, 46, and 4
Same as 7. The developer stirring / conveying member 48 has a rotation support shaft 48b protruding from a main body 48a at both ends thereof. The front rotation support shaft 48b has a 3 mm-thick developer accommodating member as shown in FIG. It penetrates the front side wall 41f of the member 41 and projects outside.

Further, a flat portion 48c as a heat radiating portion is formed at a protruding portion of the front rotation support shaft 48b protruding outside the developer accommodating member 41. As shown in FIGS. 8A and 8B, the flat portion 48c in the present embodiment has a flat rectangular cross section formed by crushing a protruding portion by rolling or the like. Thereby, the flat portion 48c is configured such that the circumferential length of the longitudinal section in the direction orthogonal to the rotation support shaft 48b is longer than the same circumference of the rotation support shaft 48b. That is, the flat portion 48 as the heat radiating portion
c has a larger surface area than the rotary support shaft 48b. The heat flowing from the main body 48a of the developer stirring / conveying member 48 passes through the copper round bar having high heat conductivity, and passes through the flat portion 48c.
, Heat is efficiently radiated to the outside air.

The distance G1 between the developing sleeve 42 and the photosensitive drum 1 shown in FIG. 1 is maintained at 180 to 220 μm by a spacer roller (not shown) made of resin. As shown, the amplitude (peak-to-peak voltage) V _pp
= 900-1100V, frequency f = 1 / T = 2650-
A rectangular wave AC voltage having a frequency of 2750 Hz and a duty ratio η = 0.4 is superimposed on a DC voltage _Vdc that is variable between 0 and 600 V and applied. Here, the duty ratio η is T
It is a value obtained as _dev / T. The portion where the gap G1 is formed, that is, the photosensitive drum 1 and the developing sleeve 42
Is the development position.

As the developer amount detecting element, three piezoelectric elements 49a, 49b and 49c are used as shown in FIGS. Piezoelectric elements 49a and 49b are provided on a front side wall (not shown) of the second developer supply device 52, and a piezoelectric element 49c is provided on a front side wall 41f of the developer accommodating member 41. A signal corresponding to the presence or absence of the developer is transmitted to a developer amount detection circuit (not shown).

When it is determined that the developer amount is insufficient based on the signal from the piezoelectric element 49c, the second developer replenisher 52
And the discharging is continued until the determination that the developer amount is insufficient is canceled. When it is determined that the developer amount is insufficient based on a signal from the piezoelectric element 49b,
When a replacement instruction for the developer storage container 6 is issued and the developer storage container 6 is replaced with a new developer storage container, the developer is discharged from the first developer replenisher 51 and the amount of the developer based on the signal from the piezoelectric element 49a. Emission continues until the shortage determination is canceled.

The developer is a one-component magnetic toner containing a polyester-based binder resin, magnetite as a magnetic material, silica as a fluidizing agent, strontium titanate as an abrasive, and no carrier particles. The weight average particle diameter is 7.5 to 8.0 μm, and the average charge amount on the developing sleeve 42 at normal temperature and normal humidity is −8 to −12 μm.
/ G, the coating amount is 0.6 to 0.9 mg / cm ² .

The developer is transported by developer stirring and conveying members 61 and 62.
Is supplied to a user or the like in a state where about 1700 g is filled in a resin developer container 6 containing resin. The user replaces the empty developer container 6 loaded in the first developer replenisher 51 with a new one filled with developer based on the developer container replacement instruction of the image forming apparatus. Thus, the developer is supplied to the image forming apparatus.

The photosensitive drum 1 has a diameter of 108 mm, a length of 360 mm, and a peripheral speed, ie, a process speed of 4 mm.
It is 50 mm / sec. FIG. 10 is an enlarged sectional view showing the structure of the cylinder portion 10a of the photosensitive drum 1. In FIG. 1, a cylinder portion 10 a of a photosensitive drum 1 includes a conductive support 12 made of pure aluminum and a photosensitive layer 11 (a charge injection blocking layer 11 a) sequentially deposited on the surface of the conductive support 12.
And a photoconductive layer 11b) exhibiting photoconductivity and a surface layer 13, and has a maximum thickness of 5 mm. Here, the charge injection blocking layer 11a is for blocking charge injection from the conductive support 12 to the photoconductive layer 11b, and is provided as necessary. The photoconductive layer 11b is made of an amorphous material containing at least a silicon atom, 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 image forming apparatus.

As shown in FIG. 11 (exploded perspective view), the photosensitive drum 1 has flanges 1 at both ends of a cylinder portion 10a.
0b and 10c are detachably screwed. The reason why it is detachable is that replacement of the planar heater 14, the planar heater support member 15, and the like, which are heating means for preventing so-called image deletion, is considered inside the cylinder portion 10a.

FIGS. 12 and 13 show the developing device 4 described above.
The conventional example 1 and the present embodiment when the output of the standard image ratio (6%) of the A4 size is performed for about 4 hours continuously for about 20,000 pages in the normal temperature and normal humidity environment for 4 hours from the start-up in the image forming apparatus provided with It illustrates the transition of the temperature T _bld image reflection density RD _max and the plate member 43 in each embodiment.

FIG. 21 shows the temperature T _bld of the plate member 43 after the continuous output, the image reflection density after the continuous output, and the conventional example 1 in the first to _seventh embodiments and the conventional examples 1 and 2. 2 is a table summarizing the relative values of the developing device costs based on 2. Embodiments 2 to 7 and Conventional Example 2 will be described later.

Here, the conventional example 1 is different from the first embodiment in that the material of the four developer stirring / conveying members 45 to 48 is all made of resin, and the portion protruding to the outside of the developing device 4, that is, the heat radiation It does not have a part.

As can be seen from FIGS. 12, 13 and 21, according to the first embodiment, in the developing device 4, the fourth developer stirring and conveying member 48 is made of a copper round bar having excellent heat conductivity. Are bent, and the rotation support shafts 48b provided at both ends thereof are projected outside through the front side wall 41f of the developer accommodating member 41, and furthermore, the projections at the front rotation support shaft 48b are formed. Since the portion is formed into a flat portion 48c having a flat rectangular cross section by rolling or the like, the surface area of the flat portion 48c is increased. Therefore, the heat flowing from the main body 48a of the developer stirring and conveying member 48 is efficiently radiated to the outside air through the copper round bar having high thermal conductivity and the flat portion 48c as the heat radiating portion. ing.

That is, according to the first embodiment, the effect of cooling the developer in the developing device 4 can be improved while suppressing an increase in the cost of the developing device 4 as compared with the conventional example 1. For this reason, it is possible to effectively prevent a decrease in image reflection density after continuous output.

<Second Embodiment> FIG. 14 shows a second embodiment.
4 is a perspective view of a fourth developer stirring and conveying member 48 according to the first embodiment.

In this embodiment, the fins 48 made of copper are attached to the rotary support shaft 48b as the heat radiating portions of the fourth developer stirring and conveying member 48, instead of the flat portions 48c of the first embodiment.
d is formed. The configuration of the fourth developer stirring / conveying member 48c and the developing device 4 in other parts is the same as that in the first embodiment.

The fin 48d is a disk 48e having a diameter of 24 mm.
And six rectangular plates 48f erected on the surface thereof. The rectangular plate 48f has a width of 5 mm and a length of 1
A rectangular long plate of 0 mm is placed on the outer surface of the
They are mounted in the radial direction at intervals of 0 degrees.

The configuration of the fin 48d is not limited to the above.

FIG. 21 shows the temperature T _bld of the plate member 43 after the continuous output, the image reflection density after the continuous output, and the relative value of the developing device cost based on Conventional Examples 1 and 2 in the second embodiment. Is shown.

From the figure, it can be seen that according to the second embodiment, the cost of the developing device is slightly higher than that of the first embodiment, but the cooling / radiating performance is higher.

Third Embodiment Next, a third embodiment will be described.

In the present embodiment, not only the fourth developer stirring and conveying member 48 but also the third developer stirring and conveying member 47 have the same configuration as the fourth developer stirring and conveying member 48. That is, the third developer stirring / conveying member 47 is formed of a copper round bar, and further, the front rotation support shaft is projected from the front side wall 41f of the developer accommodating member 41 of the developing device 4, and the projected portion is dissipated. Fins (see FIGS. 14 and 15) were provided as parts. Thereby, the surface area of the heat radiating portion is increased. The other points are the same as those in the second embodiment.

FIG. 21 shows the temperature T _bld of the plate member 43 after continuous output, the image reflection density after continuous output, and the relative value of the developing device cost based on Conventional Examples 1 and 2 in the third embodiment. Is shown.

As can be seen from the figure, according to the third embodiment, the cost of the developing device is slightly higher than that of the first embodiment, but the cooling / radiating performance is further improved.

Fourth Embodiment Next, a fourth embodiment will be described.

This embodiment is different from the third embodiment only in that the fourth embodiment does not include the fourth developer stirring and conveying member 48, and the other points are the same.

FIG. 21 shows the temperature T _bld of the plate member 43 after continuous output, the image reflection density after continuous output, and the relative value of the developing device cost based on the conventional examples 1 and 2 in the fourth embodiment. Is shown.

As can be seen from the figure, according to the fourth embodiment, the cost of the developing device is slightly lower than that of the third embodiment, but the cooling and heat radiation performance is slightly inferior. However, in comparison with Conventional Example 1, it can be seen that the cooling and heat dissipation performances are still excellent.

Fifth Embodiment Next, a fifth embodiment will be described.

In the developing device 4 according to the present embodiment, FIG.
As shown in FIG. 6, the developer layer thickness regulating member has a thickness of 50 μm.
Of stainless steel (SUS304CSP) 43d and urethane rubber 43c having a thickness of 1 mm (FIG. 16).
It is a plate-like member 43 having elasticity.

The plate member 43 is formed to be long in the front and back directions in FIG. 1, and the long side of the base end 43e side has a width w = 5.
The length of the urethane rubber 43c is 20 to 40 g / cm ^{2 in} a state in which the front end 43f is directed to the upstream side in the rotation direction (the direction of the arrow R42) of the developing sleeve 42. At the pressure of the developing sleeve 42.

The developing sleeve 42 has a diameter of 20 mm and a length of 3 mm.
It is a hollow cylinder made of stainless steel SUS305 having a diameter of 10 mm, and is subjected to an amorphous aluminum oxide particle spraying process and a spherical glass particle spraying process, so that 0.80 to 0.80 mm
Having an outer surface with a centerline roughness of 1.00 μm Ra;
It is driven to rotate at a peripheral speed of 8.5 mm / sec.

The inside of the developing sleeve 42 has a diameter of 17 to
An 18 mm magnet roller (roller permanent magnet) 44 is fixedly provided. On the surface of the magnet roller 44, a total of four magnetic poles, two S poles and two N poles, are arranged.

The developing device 4 according to the present embodiment is similar to the developing device shown in FIG.
As shown in FIG. 18, only one developer stirring and conveying member 45 made of an aluminum alloy is provided as a developer stirring and conveying member, and a rotation support shaft 45b shown in FIG. The front rotation support shaft 45b has a thickness of 2 mm.
Of the developer accommodating member 41 (see FIG. 7).

Further, a flat portion 45c is formed as a heat radiating portion at a protruding portion of the front rotation support shaft 45b protruding outside the developer accommodating member 41. The flat portion 45c in the present embodiment is shown in FIGS.
As shown in (1), the protruding portion is crushed by rolling or the like to form a flat rectangular cross section. Thereby, the surface area of the flat part 45c as the heat radiating part is increased. The heat flowing from the main body on the center side of the developer stirring / conveying member 45 passes through the aluminum material having high thermal conductivity and passes through the flat portion 45.
In c, heat is efficiently radiated to the outside air.

The developer accommodating container 6 is made of a cylindrical resin having a rectangular discharge hole 6a and containing a resin developer conveying member 61, and is filled with about 380 g of the developer. It is supplied to the user or the like in a state where it is performed.

The user or the like replaces the empty developer container 6 loaded in the developing device 4 with a new one filled with the developer, based on the instruction to replace the developer container of the image forming apparatus. The developer is supplied to the image forming apparatus.

As the developer amount detecting element, a SUS316 round bar 71 having a diameter of 1 mm to which a detecting bias is applied is used. The round bar 71 is disposed parallel to the rotation axis of the developing sleeve 42 at a position 40 degrees above the horizontal line H passing through the rotation axis of the developing sleeve 42 and at a height of 30 mm from the horizontal line H. Then, a signal corresponding to the presence or absence of the developer is transmitted to a developer amount detection circuit (not shown).

When it is determined that the developer amount is insufficient based on a signal from the round bar 71 as a developer amount detecting element,
An instruction to replace the developer container 6 is issued. When the developer container 6 is replaced with a new one, the developer container 6
The developer is discharged from, and the discharge is continued until the determination is canceled.

FIGS. 19 and 20 show the developing device 4 described above.
The conventional example 2 and the present embodiment when the output of the A4 size standard image ratio (6%) is performed for about 2,000 pages for 4 hours continuously from the start-up in an image forming apparatus equipped with It illustrates the transition of the temperature T _bld image reflection density RD _max and the plate member 43 in each embodiment.

FIG. 21 shows the temperature T of the plate member 43 after continuous output in the fifth embodiment and the second conventional example.
_{bld indicates} the image reflection density after continuous output, and the relative value of the developing device cost based on Conventional Example 2.

Here, the second conventional example is different from the fourth embodiment in that the material of the developer stirring and conveying member 45 is all made of resin and does not have a protruding portion outside the developing device 4, that is, does not have a heat radiating portion. belongs to.

The resin flow control member 73 attached to the support member 72 shown in FIG. 17 is a member for preventing toner from entering the back surface of the plate member 43 and causing a toner packing phenomenon. It is.

As can be seen from FIGS. 19, 20, and 21, according to the fifth embodiment, in the developing device 4, the developer stirring / conveying member 45 is made of an aluminum material having excellent heat conductivity. The rotation support shafts 45b provided at both ends thereof are connected to the front side wall 41f of the developer containing member 41.
Is formed, and the protruding portion of the rotary support shaft 45b on the front side is formed into a flat portion 45c having a flat rectangular cross section by rolling or the like, so that the surface area of the flat portion 45c increases. Have been. Therefore,
The heat flowing in from the center side main body of the developer stirring and conveying member 45 is efficiently radiated to the outside air at the flat portion 45c as a heat radiating portion through the aluminum material having high thermal conductivity.

That is, according to the fifth embodiment, the cooling effect of the developer in the developing device 4 can be improved while suppressing the increase in the cost of the developing device 4 as compared with the conventional example 2. For this reason, it is possible to effectively prevent a decrease in image reflection density after continuous output.

The distance G1 between the developing sleeve 42 and the photosensitive drum 1 is set to 28 by a ring-shaped spacer roller (not shown) attached to both longitudinal ends of the developing sleeve 42.
22 and between the developing sleeve 42 and the photosensitive drum 1 as shown in FIG.
_pp = 1250-1350V, frequency f = 1 / T = 195
A rectangular wave AC voltage having 0 to 2050 Hz and a duty ratio η = 0.5 is applied so as to be superimposed on a DC voltage _Vdc that is variable between −600 and 0V. Here, the duty ratio is a value obtained by η = T _dev / T.

The developer is a one-component magnetic toner containing styrene acrylic binder resin, magnetite as a magnetic material, silica as a fluidizing agent, strontium titanate as an abrasive, and no carrier particles. The initial weight average particle diameter is 7.5 to 8.0 μm, and the average charge amount on the developing sleeve 42 at normal temperature and normal humidity is +10 to 15 μm.
mC / g, the coating amount is 0.6 to 0.8 mg / cm ² .

The photosensitive drum 1 has a diameter of 30 mm and a length of 360
mm, its peripheral speed, that is, process speed is 105 mm /
sec. FIG. 23 shows the cylinder unit 10 of the photosensitive drum 1.
It is sectional drawing which shows the structure of a. In FIG. 1, a cylinder portion 10 a of the photosensitive drum 1 includes a conductive support 12 made of aluminum and an organic photosensitive layer 11 in which the following layers are sequentially deposited on the surface of the conductive support 12.

The following layers are a conductive coating layer, an undercoat layer,
A charge generation layer and a charge transport layer. The conductive coating layer is mainly composed of tin oxide and titanium oxide powder dispersed in a phenol resin, and has a thickness of 18 μm. The undercoat layer is mainly composed of modified nylon and copolymer nylon, and has a thickness of 1.0 μm. The charge generation layer is mainly composed of an acrylic resin in which a disazo pigment having absorption in a long wavelength region is dispersed, and has a thickness of 0.2 μm. The charge transport layer is mainly composed of a hydrazone compound having a hole transporting property dissolved in a polycarbonate resin, and has a thickness of 25 μm.

As shown in FIG. 24, a resin flange 10b is press-fitted into the front end of the cylinder portion 10a, and a flange 10c with a bevel gear is also press-fitted into the rear end.

In the present photosensitive drum 1 having the organic photosensitive layer 11, since there is almost no occurrence of image deletion, a heating means such as a planar heater (see 14 in FIG. 11) is not provided.

<Sixth Embodiment> Next, a sixth embodiment will be described.

In the present embodiment, the rotary support shaft 45 b on the front side of the developer
The flat portion 45c as a heat radiating portion (FIG. 1)
8) is different from the former in that aluminum fins 45d are provided as shown in FIG. Other points are the same as in the fifth embodiment.

The fin 45d is a disk 45e having a diameter of 18 mm.
And three trapezoidal plates 45f erected on its surface. The trapezoidal plate 45f has a height of 2 mm and a short side of 5 m
This is a trapezoidal plate member having a length of 8 mm and a long side of 8 mm, and is attached to the surface of the disk 45e at intervals of 120 degrees. The shape and arrangement of the fin 45d are not limited to this.

FIG. 21 shows the result of the sixth embodiment. As shown in the figure, it can be understood that the sixth embodiment is slightly higher in cost than the above-described fifth embodiment, but has higher cooling / radiation performance.

<Seventh Embodiment> Next, a seventh embodiment of the present invention will be described.

The present embodiment is different from the fifth embodiment only in that the material of the developer stirring member 45 is made of brass, and is the same as the fifth embodiment except for this point.

As shown in FIG. 21, according to the seventh embodiment, it can be understood that the cooling and heat radiation performance is slightly inferior to that of the fifth embodiment, but the cost is low.

Although the first to seventh embodiments of the present invention have been described above, the technical scope of the present invention is not limited to these embodiments.

For example, a developing device in which a magnet roller disposed in the developing sleeve rotates together with the developing sleeve, a color developing device having two or more developing devices, and a plate-like developer layer thickness regulating member are not used. Developing device having a cylindrical developer layer thickness regulating member, developing device using a two-component developer composed of toner and carrier, developing device using a developer composed only of non-magnetic toner, developing sleeve The present invention also includes a developing device that contacts the photosensitive drum, a developing device in which the developer carrying member has a belt shape instead of a sleeve shape, and an image forming apparatus including these developing devices. In other words, all changes that are perceived as minor changes in light of the spirit of the present invention are within the technical scope of the present invention.

Therefore, when performance is prioritized over cost, a material having high heat conductivity such as magnesium, beryllium, or molybdenum is contained as a material constituting a part or all of the developer stirring and conveying member. Is also good.

[0096]

As described above, according to the present invention,
Even when the image output is performed at a high speed and continuously, it is possible to prevent a decrease in the image density due to a rise in the temperature of the developer in the developing device, while keeping the cost increase low.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a configuration of a developing device according to a first embodiment.

FIG. 2 is a perspective view illustrating a configuration of first, second, and third developer stirring / conveying members.

FIG. 3 is a perspective view showing a configuration of a developing sleeve according to the first embodiment.

FIG. 4 is a side view showing a configuration of a plate-shaped member as a developer layer thickness regulating member according to the first embodiment.

FIG. 5 is a diagram illustrating an arrangement position of a fourth developer stirring and conveying member in the first embodiment.

FIG. 6 is a perspective view illustrating a configuration of a fourth developer stirring and conveying member according to the first embodiment.

FIG. 7 is an enlarged cross-sectional view of the vicinity of a front side wall of a developer container of the developing device according to the first embodiment.

FIGS. 8 (a) and (b) are views for explaining that a rotary support shaft of a fourth developer stirring and conveying member is formed into a flat portion as a heat radiating portion by rolling.

FIG. 9 is a diagram illustrating a developing bias according to the first embodiment.

FIG. 10 is an enlarged vertical sectional view of the photosensitive drum according to the first embodiment.

FIG. 11 is an exploded perspective view of the photosensitive drum according to the first embodiment.

FIG. 12 is a diagram comparing the relationship between the number of output images and the image reflection density between the first embodiment and the first conventional example.

FIG. 13 is a diagram comparing the relationship between the number of output images and the temperature of the plate member between the first embodiment and the first conventional example.

FIG. 14 is a perspective view illustrating a configuration of a fourth developer stirring and conveying member according to the second embodiment.

FIG. 15 is a side view illustrating a configuration of a fin of a fourth developer stirring and conveying member according to the second embodiment.

FIG. 16 is a longitudinal sectional view showing a configuration of a plate-shaped member as a developer layer thickness regulating member according to a fifth embodiment.

FIG. 17 is a longitudinal sectional view illustrating a configuration of a developing device according to a fifth embodiment.

FIGS. 18 (a) and (b) are views for explaining that a rotary support shaft of a developer stirring and conveying member is formed into a flat portion as a heat radiating portion by rolling.

FIG. 19 is a diagram comparing the relationship between the number of output images and the image reflection density between the fifth embodiment and the second conventional example.

FIG. 20 is a diagram comparing the relationship between the number of output images and the temperature of the plate member between the fifth embodiment and the second conventional example.

FIG. 21 is a diagram showing relative values of a plate-like member temperature T _bld after continuous output, an image reflection density after continuous output, and a developing device cost for Embodiments 1 to 7 and Conventional Examples 1 and 2.

FIG. 22 is a diagram illustrating a developing bias according to the fifth embodiment.

FIG. 23 is an enlarged vertical sectional view of the photosensitive drum according to the first embodiment.

FIG. 24 is an exploded perspective view showing a configuration of a photosensitive drum according to the fifth embodiment.

FIG. 25 is a side view showing a configuration of a fin of a developer stirring and conveying member according to the sixth embodiment.

FIG. 26 is a longitudinal sectional view showing a configuration of a conventional developing device.

FIG. 27 is a longitudinal sectional view showing the configuration of another conventional developing device.

FIG. 28 shows a plate-like member temperature T in a conventional developing device.
FIG. 6 is a diagram illustrating a relationship between _bld and image reflection density.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 image carrier (photosensitive drum) 2 charging means (charging roller) 3 electrostatic latent image forming means (exposure means) 4 developing device 14 heating means (plane heater) 41 developer accommodating member 42 developer carrier (development sleeve) 43) Developer layer thickness regulating member (plate-like member) 45b Rotation support shaft 45 Developer stirring / conveying means (third developer stirring / conveying member) 48 Developer stirring / conveying means (fourth developer stirring / conveying member) 48b Rotary support shaft 48c Heat radiating portion (flat portion) 48d Heat radiating portion (fin) 74 Development Agent scattering prevention member

Claims (10)

[Claims] A developer agitating / conveying means for agitating / conveying a powder developer stored in a developer accommodating member; a developer carrying member for carrying and transporting the developer on a surface; A developer layer thickness regulating member for regulating the layer thickness of the developer carried on the surface of the carrier, wherein the developer whose layer thickness is regulated faces the surface of the image carrier on the surface of the developer carrier. A developer agitating / conveying unit, which is rotatably supported by the developer accommodating member and agitates / conveys the developer in the developer accommodating member. A developing device comprising: one developer stirring / conveying member; and at least one of the developer stirring / conveying members has a heat radiating portion protruding outside the developer accommodating member. 2. When the developer stirring / conveying means includes a plurality of the developer stirring / conveying members, the developer stirring / conveying member is located at a position closest to the developer layer thickness regulating member and an uppermost portion of the developer carrying member. The developing device according to claim 1, wherein the developer stirring and conveying member having the heat radiating unit is disposed at a higher position. 3. The developing device according to claim 1, wherein the heat radiating unit is provided on a rotation support shaft rotatably supported by the developer accommodating member. 4. The peripheral length of a vertical section in a direction perpendicular to the rotation support shaft, wherein the circumference of the heat radiating portion is longer than the circumference of the rotation support shaft. 3. The developing device according to claim 1. 5. The developing device according to claim 4, wherein the heat radiating portion is a flat portion formed by crushing the rotation support shaft. 6. The developing device according to claim 4, wherein the heat radiating portion is a fin attached to the rotation support shaft. 7. A developer scattering prevention member that covers a portion of the surface of the developer carrier that is located between the developer layer thickness regulating member and the image carrier. Item 1, 2, 3, 4, 5, or 6
An image forming apparatus according to claim 1. 8. The developing device according to claim 7, wherein the developer scattering prevention member is formed of a material mainly containing aluminum, copper, or zinc. 9. An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the image carrier, a developing means for adhering toner to the electrostatic latent image and developing it as a toner image, And a transfer means for transferring the toner image to a transfer material, wherein the developing means comprises:
9. The image forming apparatus according to claim 8, wherein: 10. The image forming apparatus according to claim 9, wherein the image carrier has a heating unit inside.