JPH11174795A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the definition of an output image from being deteriorated caused by temperature rise in a developing device and an image forming device provided with the developing device by providing a temperature lowering means lowering the temperature of at least one of a developer housing means, a developer carrying means and a developer layer forming means in the image forming device. SOLUTION: A latent image formed on an image carrying means is developed by a developer layer carried and formed on the developer carrying means. Then, the device is provided with the temperature lowering means lowering the temperature of at least one of the developer housing means, the developer carrying means and the developer layer forming means. For example, the developing device A is constituted so that the part of the bottom of the developer container 1, which is set as the developer housing means, being near to a developing sleeve is formed to the a tube-like member 1a which is made of non-magnetic metal such as alminum whose heat conductivity is excellent, whose inside is formed to be a hollow part 1b and which is provided with many fins 1c at the inside wall surface. By making cooling water flow to the inside of the hollow part 1b, the temperature of the member 1a being the part of the bottom of the container 1 being near to the developing sleeve is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

More specifically, a developer accommodating means for accommodating a powdery developer, a developer accommodating means for accommodating the developer in the developer accommodating means on a surface, and a developer accommodating means on the surface of the developer accommodating means. It has a developer layer forming means for forming a layer of developer, and is formed on an image bearing means such as an electrophotographic photosensitive member and an electrostatic recording dielectric by the developer layer carried and formed on the developer carrying means. The present invention relates to a developing device for developing a latent image. The invention also relates to an image forming apparatus provided with the developing device.

[0003]

2. Description of the Related Art FIG. 12 shows a schematic configuration of an example of a developing device as described above.

The developing device A of this embodiment is a developing device using a one-component magnetic developer (toner) as a powder developer, and forms an electrostatic latent image formed on an image bearing means B by an appropriate process means. Is developed as a toner image.

The image bearing means B is a rotating drum type electrophotographic photosensitive member in this embodiment. The photoreceptor B is driven to rotate at a predetermined peripheral speed (process speed) in the clockwise direction of the arrow, and an electrostatic latent image corresponding to the target image information is formed on its outer peripheral surface by a well-known electrophotographic process means (not shown). An image is formed.

In the developing device A, reference numeral 1 denotes a developing container as developer storing means, which stores a one-component magnetic toner t.

Reference numeral 2 denotes a developing sleeve made of a non-magnetic material as a developer carrying means, which is rotatably supported between a rear side wall and a front side wall of the developing container 1 through a bearing.
The front side of the developing sleeve 2 is exposed to the outside, and the rear side thereof faces the inside of the developing container 1.

Reference numeral 3 denotes a magnet roller inserted into the developing sleeve 2 as a magnetic field generating means. The magnet roller 3 is fixed non-rotatably, and the developing sleeve 2 is driven to rotate around the fixed magnet roller 3 by a driving system (not shown) at a predetermined peripheral speed in a counterclockwise direction indicated by an arrow.

Reference numeral 4 denotes an elastic plate-like member as a developer layer forming means for forming a thin layer of toner on the surface of the developing sleeve 2. In this embodiment, the elastic plate-shaped member 4 is brought into contact with the upper surface of the developing sleeve 2 with an abdominal contact with an appropriate pressure, and one long side is fixed to the lower end of the front wall of the developing container. It is set up.

Reference numeral 5 denotes a developer entry preventing member for preventing the toner t from entering the back side of the elastic plate member 4 as the developer layer forming means.

Reference numerals 6 and 7 denote first and second toner agitating and rotating members disposed in the developing container 1, respectively, which are rotationally driven at a predetermined speed in a clockwise direction indicated by an arrow by a drive system (not shown). The toner in the developing container 1 is stirred by the rotation of the first and second toner stirring rotating members 6 and 7, sent to the developing sleeve 2, and supplied to the rear side of the developing sleeve 2.

The developing device A is arranged such that the developing sleeve 2 is brought into close contact with the photosensitive member B, which is a member to be developed, in a non-contact manner with a predetermined small gap α. Alternatively, the developing sleeve 2 is provided so as to be in contact with the photosensitive member B.

Reference symbol E denotes a developing bias application power source for applying a predetermined developing bias to the developing sleeve 2.

A part of the one-component magnetic toner t, which is a developer supplied to the rear side of the developing sleeve 2, is applied to the surface of the developing sleeve 2 by a magnetic field of a magnet roller inside the developing sleeve. And is transported as the developing sleeve 2 rotates.

The thickness of the magnetically attracted layer of the toner is regulated at the contact portion of the elastic plate member 4 as the developer layer forming means with the developing sleeve 2, and is coated on the developing sleeve 2 as a predetermined thin layer. It is also triboelectrically charged.

The thin toner layer is applied to the subsequent developing sleeve 2
, The toner is transported to a developing portion a, which is a portion of the photoconductor B and the developing sleeve 2 that is close to or in contact with each other, and the toner of the thin toner layer on the developing sleeve 2 side is subjected to the action of the magnetic field and the developing bias. Then, the electrostatic latent image on the surface of the rotating photoconductor B is selectively developed as a toner image by selectively shifting to the photoconductor B side corresponding to the electrostatic latent image.

The toner on the developing sleeve 2 that has not been subjected to the development is returned and transported into the developing container 1 by the subsequent rotation of the developing sleeve 2.

The toner image on the surface of the rotating photosensitive member B is transferred to a recording material by a transfer means (not shown), and the recording material is discharged as an image formed matter via a fixing means (not shown).

After the transfer of the toner image to the recording material, the surface of the photosensitive member B is cleaned by the cleaning means and is repeatedly used for image formation.

The developer layer forming means 4 is made of a magnetic or non-magnetic blade member, and the lower side thereof is brought into non-contact with the developing sleeve 2 at a predetermined small gap β as shown in FIG. There is also a configuration in which the magnetic attraction layer of the toner on the developing sleeve 2 is regulated as a predetermined thin layer at a gap interval β in some cases.

[0021]

However, in such a conventional developing device configuration, when the image output operation of the image forming device is continuously performed without an appropriate pause interval, the quality of the developer in the developing device is deteriorated. This causes a problem that various output image qualities are deteriorated mainly by a decrease in image density.

It is known that the main cause is a rise in the temperature inside the developing device and the image forming apparatus provided with the developing device.

Therefore, the present invention prevents a decrease in output image quality due to a rise in temperature inside a developing device and an image forming apparatus in which the developing device is disposed even when image output is continuously performed, and provides high quality output. It is an object of the present invention to provide a developing device and an image forming apparatus capable of obtaining an image.

[0024]

According to the present invention, there is provided a developing apparatus and an image forming apparatus having the following constitution.

(1) A developer accommodating means for accommodating a powdery developer, a developer accommodating means for carrying the developer in the developer accommodating surface on a surface thereof, and developing on the surface of the developer accommodating means. A developing device that has a developer layer forming unit that forms a layer of developer, and that develops a latent image on the image carrying unit with a developer layer that is carried and formed on the developer carrying unit;
A developing device comprising: a temperature lowering means for lowering at least one of the developer carrying means and the developer layer forming means.

(2) The developing device according to (1), wherein the developer layer forming means is in contact with the developer carrying means.

(3) The developing device according to (1) or (2), wherein the temperature lowering means includes means for passing a gaseous cooling medium into the developer carrying means.

(4) The developing device according to (1) or (2), wherein the temperature lowering means includes means for passing a liquid cooling medium through the developer carrying means.

(5) The operation of the temperature lowering means is performed at least in accordance with the temperature near the contact portion between the developer layer forming means and the developer carrying means (1) to (4). The developing device according to any one of the above.

(6) The developing device according to any one of (1) to (5), wherein the developer carrying means is rotatably supported by the developer accommodating means.

(7) An image forming apparatus for forming a latent image on an image carrier and developing the latent image with a powdery developer to form an image. An image forming apparatus, wherein the developing means for developing with a body developer is the developing device according to any one of (1) to (6).

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment (FIGS. 1 and 2) FIG. 1 is a schematic configuration diagram of a developing device according to the present embodiment.
The same reference numerals are given to constituent members and portions common to the developing device of FIG. 12 or 13 described above, and the description thereof will not be repeated. The same applies to the second to fourth embodiments described later.

The developing device A of the present embodiment includes a portion 1a near the developing sleeve at the bottom of the developing container 1 as a developer accommodating means.
Is made of a non-magnetic metal having good thermal conductivity such as aluminum and the inside is hollow 1b, and a number of fins 1 are formed on the inner wall surface.
c into a tubular member, and the hollow portion 1 of the member 1a
The temperature of the member 1a, which is a portion of the bottom of the developing container 1 close to the developing sleeve, is lowered by flowing cooling water into the developing container 1b.

FIG. 2 shows a cooling water circulation path. One longitudinal end and the other end of the hollow portion 1b of the member 1a are connected by a cooling water conduit 1c. A cooling water circulation means (pump) 8 and a cooling means (radiator) 9 are interposed.

Reference numeral 10 denotes a replenishment toner hopper or a replenishment toner bin for the developing container 1. The toner t in the developing container 1 is gradually consumed and reduced in the development of the electrostatic latent image on the photoconductor B. The amount of toner in the developing container 1 is detected by a detection unit (not shown), and when the amount decreases to a predetermined allowable lower limit, a warning to that effect is issued. In response to the warning, the user replenishes the developing container 1 with the replenishing toner. Alternatively, an appropriate amount of toner is automatically supplied at an appropriate time. The toner replenished into the developing container 1 is stirred by the rotation of the third toner stirring and rotating member 11 and the rotation of the first and second toner stirring and rotating members 6 and 7, and is sent toward the developing sleeve 2. It is supplied to the rear side of the developing sleeve 2.

In the developing device A of the present embodiment, the developing sleeve 2 as a developer carrying means is a hollow cylinder made of an aluminum alloy having a diameter of 24.5 mm, and has a rotary support shaft at both ends thereof. It is rotatably supported on the side and rear side walls via bearings, and is rotationally driven at a peripheral speed of 470.4 mm / sec in a counterclockwise direction indicated by an arrow.

The outer surface of the developing sleeve 2 is subjected to a blasting treatment by spraying spherical glass particles and then coated with a phenol resin, crystalline graphite, carbon or the like and having a volume resistance of 100 Ωcm or less (film thickness 10 μm).
m to 14 μm) and various types of polishing, and the center line average roughness of the outer surface is 0.70 to 0.90 μm.
mRa.

The distance α between the developing sleeve 2 and the photosensitive member B is 2
It is set to 10 to 250 μm.

The power supply E applies a developing bias to the developing sleeve 2 with an amplitude of 1350 to 1650 V and a frequency of 2400.
A rectangular AC voltage of ０００3000 Hz is applied while being superimposed on a DC voltage variable between 0 V and +600 V.

The developer layer forming means 4 is of a blade type similar to that shown in FIG. 13 and is not in contact with the developing sleeve 2. The blade member 4 is made of SPCC and has a thickness of 1.4 mm and a width of 10 mm.
mm, length 306 mm, distance β from developing roller 2 = 20
It faces the developing sleeve 2 at 0 to 260 μm.

Magnet roller 3 as magnetic field generating means
Has five magnetic poles S1, N1, S2, N2, and S3. The developer is drawn up by the rotation of the developing roller 2 and the pole S1
(The vertical component magnetic flux density on the surface of the developing sleeve is 600 Gauss.
The thickness of the one-component magnetic toner layer pumped at 700 Gauss from the developing sleeve surface is regulated by the blade member 4 so as to be reduced in thickness. In the developing section a, the developing pole N
2 (The vertical component magnetic flux density on the developing sleeve surface is 950 Ga
The toner raised at a rate of (uss to 1050 Gauss) develops the electrostatic latent image on the surface of the photoconductor B. The toner not subjected to the development is returned into the developing container 1 by the subsequent rotation of the developing sleeve 2.

In the developing device of this embodiment, the average charge amount q of the developer (toner) on the developing sleeve 2 is -6 to -2.
0 μC / g, the coating amount m is 0.7 to 1.0 mg / cm ² , and the initial weight average particle size of the developer is 8.5 to 9.5 μm.
It is.

In the above-described embodiment, the temperature lowering means 1a, 8
When the external environment is at room temperature and normal humidity and the developing device A is in a steady state during continuous operation, the temperature in the vicinity of the opposing portion between the developing sleeve 2 and the blade member 4 is about The cooling water temperature before cooling the developing device is about 10 ° C., and the cooling water temperature after cooling is about 20 ° C.

The image reflection density (original reflection density 1.1) when an image was continuously output for 10 minutes was 1.45.

On the other hand, when the developing device A is not provided with the temperature lowering means, the temperature in the vicinity of the opposing portion between the developing sleeve 2 and the blade member 4 is about 40 ° C., and the image is output continuously for 10 minutes. Image reflection density (original reflection density 1.
1) was 1.31.

<Second Embodiment> (FIGS. 3 to 5) FIG. 3 is a schematic structural view of a developing device in the present embodiment.

The developing device A of this embodiment is provided with a developer entry preventing member 5 for preventing the toner t from entering the back side of the elastic plate-like member 4 as a developer layer forming means. It is made of a good non-magnetic metal and has a hollow 5ab on the inside, a tubular member having a number of fins 5b on the inner wall surface, and cooling water flowing through the hollow portion 5a of the member 5,
The temperature of the member 5 was reduced.

FIG. 4 shows a cooling water circulation path. One longitudinal end and the other end of the hollow portion 5a of the member 5 are connected by a cooling water conduit 5c. Cooling water circulation means (pump) 8 and cooling means (radiator)
Nine are intervening.

In the developing device A of this embodiment, the developing sleeve 2 as a developer carrying means is a stainless steel hollow cylinder having a diameter of 20 mm, and has a rotary support shaft at both ends thereof. It is rotatably supported on the side wall via a bearing, and is rotationally driven in the counterclockwise direction of the arrow at a peripheral speed of 157.5 mm / sec.

The outer surface of the developing sleeve 2 has been subjected to blasting by spraying spherical glass particles or amorphous alumina particles.
It is a rough surface of 0.40 to 0.60 μm Ra.

The distance α between the developing sleeve 2 and the photosensitive member B is 2
It is set to 70 to 330 μm.

The power supply S applies a developing bias to the developing sleeve 2 with an amplitude of 1250 to 1350 V and a frequency of 1750.
矩形 1850 Hz rectangular AC voltage is -400 to -600
The voltage is superimposed on a DC voltage that is variable between V and V.

The developer layer forming means 4 is an elastic plate-like member brought into contact with the developing sleeve 2 as in FIG.

FIG. 5 is an enlarged model view of the elastic plate member 4. The elastic plate member 4 includes a stainless steel plate (thickness 0.06 mm) 4a and a urethane rubber layer (thickness 0.9 to 0.96 mm).
(2 mm, hardness: 60 ° to 70 °) 4b, and the surface of the urethane rubber layer 4b is in contact with the developing sleeve 2.

The surface of the urethane rubber layer 4b and the developing sleeve 2
Is about 0.5 mm, and an angle ζ = 28 ° formed between a straight line b connecting the center P of the pressed area and the rotation center O of the developing sleeve 2 and a vertical line c passing through the rotation center O. ~ 32 °
It is.

Pressing force p of the elastic plate member 4 against the developing sleeve 2 (per unit length along the axis of the developing sleeve 2) =
10 to 20 g / cm.

The elastic plate member 4 has a length of about 210 m.
m, a rectangular shape having a width of 17 mm, and one of the long sides of the plate member having a width of about 5 mm is fixed to the lower end of the front wall of the developing container 1. The other long side is a free end E, and protrudes upstream of the elastic plate-shaped member 4 in the rotation direction of the developing sleeve from the pressure contact portion with the developing sleeve 2. The distance PE has a close relationship with the amount of applied toner, but is 3.5 mm when the elastic plate member 4 is new.

Magnet roller 3 as magnetic field generating means
Are perpendicular to the magnetic flux density on the developing sleeve surface of the developer pumping pole S2 and the developing pole S1.
50 Gauss, 900-1000 Gauss.

In the developing device of this embodiment, the average charge amount q of the developer (toner) on the developing sleeve 2 is -10 to-
20 μC / g, application amount m is 0.7 to 1.0 mg / cm ²
And the initial weight average particle size of the developer is 7 to 8 μm.

The temperature lowering means 5.8,...
When the external environment is at room temperature and normal humidity and the developing device A is in a steady state during continuous operation, the temperature in the vicinity of the opposing portion between the developing sleeve 2 and the elastic plate member 4 is The cooling water temperature before cooling the developing device is about 10 ° C., and the cooling water temperature after cooling is about 20 ° C.

The image reflection density (document reflection density 1.1) when outputting images continuously for 10 minutes was 1.40.

On the other hand, when the developing device A is not provided with the temperature lowering means, the temperature in the vicinity of the opposing portion between the developing sleeve 2 and the elastic plate member 4 is about 47 ° C., and the image output is continued for 10 minutes. Reflection density (original reflection density 1.
1) was 1.27.

<Third Embodiment> (FIGS. 6 and 7) FIG. 6 is a schematic configuration diagram of a developing device in the present embodiment.

The developing device A of this embodiment is a contact type device using a non-magnetic one-component developer (toner) as a powder developer.

Developing sleeve 2 as developer carrying means
Is obtained by forming a surface layer 2b of silicon rubber having a thickness of 2 mm and a volume resistance of about 10 ¹¹ Ωcm on the outer peripheral surface of an aluminum alloy cylinder 2a having a diameter of 18 mm. The center layer average roughness of the outer surface of the surface layer 2b is 0.50 to 0.70 μmR.
It is a rough surface of a.

The developing sleeve 2 is pressed against the photosensitive member B,
It is driven to rotate at a peripheral speed of 138 mm / sec in the counterclockwise direction of the arrow. The width d (= development portion a) of the pressure contact area of the developing sleeve 2 with the photoconductor B is 5 to 10 mm, and the aluminum alloy cylinder 2 a of the developing sleeve 2 is applied with a developing bias of 0 to −600 V from the power source E. A variable DC voltage is applied between them.

Since the developer of the developing device in this embodiment is a non-magnetic toner, it cannot be restrained by a magnetic force on the surface of the developing sleeve. 12 transports the non-magnetic toner to the surface of the developing roller 2 physically.
Apply.

As the developer conveying / applying means 12, a rotating roller including a foamed silicone rubber layer 12a or the like can be suitably used. Reference numeral 12b is a core metal of the roller. The width e of the pressure contact area between the developing sleeve 2 and the toner application roller 12 is about 8 mm.
It is. An appropriate bias voltage may be applied between the developing sleeve 2 and the toner application roller 12 from the power supply E12.

The thickness of the layer of non-magnetic toner applied to the surface of the rotating developing sleeve 2 by the toner applying roller 12 is regulated by the elastic plate-shaped member 4 in contact with the developing sleeve 2 as a developer layer forming means. The developing sleeve 2 is conveyed to a developing site a, which is a pressure contact area between the photoconductor B and the developing sleeve 2 by the subsequent rotation of the developing sleeve 2, and the toner of the toner thin layer on the developing sleeve 2 side is developed at this developing site. Under the action of the bias, the electrostatic latent image on the surface of the rotating photoconductor B is selectively developed corresponding to the electrostatic latent image on the photoconductor B side, and is sequentially developed as a toner image.

The toner on the developing sleeve 2 which has not been subjected to the development is returned and transported into the developing container 1 by the subsequent rotation of the developing sleeve 2.

In this embodiment, the elastic plate-shaped member 4 as the developer layer forming means is a rectangular stainless plate (0.06 mm thick) having a length of about 210 and a width of 16 mm. Is a smooth surface of 0.10 to 0.20 μm Ra.

One of the long sides of the elastic plate member 4 is about 5 m.
It is fixed to the lower end of the front wall of the developing container 1 with a width of m. The other long side is a free end E, and protrudes upstream of the elastic plate-shaped member 4 in the rotation direction of the developing sleeve from the pressure contact portion with the developing sleeve 2.

The width f of the pressure contact area between the elastic plate member 4 and the developing sleeve 2 is about 3 mm, and passes through a straight line b connecting the center P of the pressure contact area with the rotation center O of the development sleeve 2 and the rotation center O. The angle ζ formed by the vertical line c is 28 ° to 32 °. The distance PE is about 3 mm, and the pressing force p (per unit length along the axis of the developing sleeve 2) of the elastic plate member 4 with the developing sleeve 2 is 15 to 20 g / cm.

In the developing device of this embodiment, the average charge amount q of the developer (toner) on the developing sleeve 2 is -20 to-
30 μC / g, application amount m is 0.5 to 0.8 mg / cm ²
And the initial weight average particle size of the developer is 6.5 to 7.0 μm.
m.

The developing device A of this embodiment includes a developing sleeve 2
The temperature of the developing sleeve 2 is lowered by flowing cooling air into the hollow portion c.

FIG. 7 shows a cooling air circulation path. One longitudinal end and the other end of the hollow portion c of the developing sleeve 2 are connected by a cooling air conduit 2d.
Air circulation means (pump) 8 and cooling means (radiator) 9 are interposed in the middle of the path.

In this embodiment, the temperature lowering means 2.8.
When the external environment is at room temperature and normal humidity and the developing device A is in a steady state during continuous operation, the temperature in the vicinity of the opposing portion between the developing sleeve 2 and the elastic plate member 4 is The air temperature before cooling the developing device is about 15 ° C., and the air temperature after cooling is about 23 ° C.

The image reflection density (original reflection density 1.1) when an image was output continuously for three minutes was 1.35.

On the other hand, when the developing device A is not provided with the temperature lowering means, the temperature in the vicinity of the opposing portion between the developing sleeve 2 and the elastic plate member 4 is about 44 ° C., and the image output is continuously performed for three minutes. Image reflection density (original reflection density 1.1)
Was 1.21.

<Fourth Embodiment> (FIGS. 8 to 11) FIG. 8 is a schematic structural view of a developing device in the present embodiment.
FIG. 9 is an enlarged model view of an elastic plate-shaped member as a developer layer forming means.

The developing device A of this embodiment uses a non-magnetic one-component developer (toner) as a powder developer similarly to the developing device of the third embodiment. However, the developing sleeve 4 as a developer carrying means is opposed to the photoconductor B in a non-contact manner.

The developing sleeve 2 is a stainless steel cylinder having a diameter of 20 mm, and is driven to rotate at a peripheral speed of 157.5 mm / sec in a counterclockwise direction indicated by an arrow.

The outer surface of the developing sleeve 2 is firstly roughened by spraying spherical glass particles and then irregular alumina particles, and the center line average roughness of the outer surface is 0.25. It is a rough surface of ~ 0.40 µmRa.

The distance α between the developing sleeve 2 and the photosensitive member B is 2
It is set to 70 to 330 μm.

The power supply E applies a developing bias to the developing sleeve 2 with an amplitude of 1250 to 1350 V and a frequency of 2350.
A substantially rectangular AC voltage of up to 2450 Hz is 0 V to +500 V
Is superimposed on a variable DC voltage and applied.

In this embodiment, the elastic plate-shaped member 4 as the developer layer forming means has a width of 16 mm and a length of 298-30.
7mm rectangular phosphor bronze plate (0.12mm thickness) 4c
And a urethane rubber plate (0.9 mm thick) 4d having a width of 6 mm and a length of 298 to 307 mm, and a two-layer bonding structure. One of the long sides of the phosphor bronze plate 4c is screwed to the front wall of the developing container 1. The phosphor bronze plate 4
The surface of the urethane rubber plate 4d is pressed against the surface of the developing sleeve 2 by the spring elastic force of c.

The free end of the elastic plate-shaped member 4 protrudes 0.5 to 1 mm upstream from the pressure contact portion of the elastic plate-shaped member 4 with the developing sleeve 2 in the rotation direction of the developing sleeve.

The width g of the pressure contact area between the surface of the urethane rubber plate 4d of the elastic plate member 4 and the developing sleeve 2 is about 0.5 mm, and the center P of the pressure contact area and the rotation center O of the developing sleeve 2 The angle す between the connecting straight line b and the vertical line c passing through the rotation center O is 70 ° to 74 °.

The pressing force p of the elastic plate member 4 against the developing sleeve 2 (per unit length along the axis of the developing sleeve 2) =
10 to 15 g / cm.

The elastic plate member 4 in contact with the developing sleeve 2
The non-magnetic one-component toner t on the surface of the rotary developing sleeve 2
Is applied, and the layer thickness is regulated to be thinned.

In the developing device of this embodiment, the average charge amount q of the developer (toner) on the developing sleeve 2 at normal temperature and normal humidity
Is −15 to −20 μC / g, and the coating amount m is 0.5 to 0.8.
mg / cm ² , and the initial weight average particle size of the developer is 6.
5 to 7.0 μm.

The image forming apparatus according to the present embodiment also has the third
As in the case of the developing device of the third embodiment, the temperature of the developing sleeve 2 is reduced by flowing cooling air into the hollow portion 2c of the developing sleeve 2.

FIG. 10 shows a cooling air circulation path.
One end and the other end of the hollow portion 2c of the developing sleeve 2 are connected by a cooling air conduit 2d, and an air circulating means (pump) 8 and a cooling means (radiator) are provided in the course of the cooling air conduit 2d. 9) intervened.

In the present embodiment, the temperature T near the contact portion between the developing sleeve 2 and the elastic plate member 4 is detected, and the temperature lowering means is controlled accordingly. That is, in FIG.
Reference numeral 13 denotes a temperature detecting unit which is disposed at an appropriate position of the developing device and detects a temperature T near a contact portion between the developing sleeve 2 and the elastic plate-shaped member 4. Reference numeral 14 denotes detected temperature information (electric signal) from the temperature detecting unit 13. This is control means for controlling the cooling means 9 upon receipt.

The control means 9 changes the input power P of the air to the cooling means 9 according to the detected temperature information T from the temperature detecting means 13 in accordance with a control table (control reference) as shown in FIG.

[0096] When the external environment is [normal temperature and normal humidity] and the developing device A is in a steady state during continuous operation, the temperature near the opposing portion between the developing sleeve 2 and the elastic plate member 4 is about 38 ° C., The air temperature before cooling the developing device is about 10
At 0 ° C., the air temperature after cooling is about 20 ° C.

The image reflection density (original reflection density 1.1) when an image was output continuously for 5 minutes was 1.35.

On the other hand, when the developing device A is not provided with the temperature lowering means, the temperature in the vicinity of the opposing portion between the developing sleeve 2 and the elastic plate member 4 is about 47 ° C., and the image output is continuously performed for 5 minutes. Image reflection density (original reflection density 1.1)
Was 1.23.

[0099] If the external environment is low temperature and low humidity (about 10 ° C, 5
% RH)], and when the developing device A is in a steady state during continuous operation, the developing sleeve 2 and the elastic plate member 4
Is about 33 ° C., the air temperature before cooling the developing device is about 10 ° C., and the air temperature after cooling is about 18 ° C.

The image reflection density (original reflection density 1.1) when the image was output continuously for 5 minutes was 1.35.

On the other hand, when the developing device A is not provided with the temperature lowering means, the temperature in the vicinity of the opposing portion between the developing sleeve 2 and the elastic plate member 4 is about 47 ° C., and the image output is continuously performed for 5 minutes. Image reflection density (original reflection density 1.1)
Was 1.23.

. If the external environment is high temperature and high humidity (about 30 ° C, 8
0% RH)], and when the developing device A is in a steady state during continuous operation, the temperature near the opposing portion between the developing sleeve 2 and the elastic plate member 4 is about 44 ° C. The air temperature before cooling is about 10 ° C., and the air temperature after cooling is about 20 ° C.

The image reflection density (original reflection density 1.1) when images were output continuously for 5 minutes was 1.25.

On the other hand, when the developing device A is not provided with the temperature lowering means, the temperature in the vicinity of the opposing portion between the developing sleeve 2 and the elastic plate member 4 is about 47 ° C., and the image output is continuously performed for 5 minutes. Image reflection density (original reflection density 1.1)
Was 1.02.

On the other hand, when the input power of the cooling means 9 was not switched, the power consumption was twice as large on average.

<Others> a) Although the four embodiments have been described above, it is needless to say that changes can be made within the scope of the present invention.

B) A developing device having two or more developer carrying means, a developing device having a cylindrical developer carrying means, a developing device using a two-component developer composed of toner and a carrier, a belt-like device The present invention can be applied to a developing device having the developer carrying means.

C) In the image forming apparatus, the image carrier is not limited to the electrophotographic photosensitive member. An electrostatic recording dielectric or a magnetic recording magnetic material may be used. Further, an electrostatic latent image forming means for these image carriers is also appropriate. A transfer method or a direct method may be used.

[0109]

As described above, according to the present invention, even when the image output is continuously performed, the deterioration of the output image quality due to the temperature rise inside the developing device and the image forming apparatus provided with the developing device is prevented. It is possible to provide a developing device and an image forming apparatus that prevent the image formation and obtain a high-quality output image.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a developing device according to a first embodiment.

Fig. 2 Cooling water circulation path diagram

FIG. 3 is a schematic configuration diagram of a developing device according to a second embodiment.

FIG. 4 Cooling water circulation path diagram

FIG. 5 is an enlarged model view of an elastic plate-shaped member as a developer layer forming means.

FIG. 6 is a schematic configuration diagram of a developing device according to a third embodiment.

FIG. 7 is a cooling air circulation path diagram

FIG. 8 is a schematic configuration diagram of a developing device according to a fourth embodiment.

FIG. 9 is an enlarged model view of an elastic plate-shaped member as a developer layer forming means.

FIG. 10 is a diagram of a cooling air circulation path and a control system.

FIG. 11 is a control table.

FIG. 12 is a schematic configuration diagram of a conventional developing device.

FIG. 13 is a schematic configuration diagram of another conventional developing device.

[Explanation of symbols]

A Overall Code of Developing Device B Image Carrier (Electrophotographic Photoconductor) 1 Developing Container 2 Developing Sleeve (Developer Carrier) 3 Magnet Roller 4 Blade or Elastic Plate Member (Developer Layer Forming Means) 8 Cooling Water or Cooling Air circulation means (pump) 9 Cooling means (radiator)

Claims (7)

[Claims] 1. A developer accommodating means for accommodating a powdered developer, a developer carrying means for carrying a developer in the developer accommodating means on a surface, and a developer on the surface of the developer carrying means. A developing device for developing a latent image on the image carrying means by means of a developer layer carried on the developer carrying means, the developer containing means comprising: A developing device comprising: a temperature lowering means for lowering at least one of the supporting means and the developer layer forming means. 2. The developing device according to claim 1, wherein said developer layer forming means contacts said developer carrying means. 3. The developing device according to claim 1, wherein said temperature lowering means includes means for allowing a gaseous cooling medium to pass through said developer carrying means. 4. The developing device according to claim 1, wherein said temperature lowering means includes means for allowing a liquid cooling medium to pass through said developer carrying means. 5. The operation according to claim 1, wherein the operation of the temperature lowering means is performed at least in accordance with a temperature near a contact portion between the developer layer forming means and the developer carrying means. The developing device according to any one of the above. 6. The developing device according to claim 1, wherein said developer carrying means is rotatably supported by said developer accommodating means. 7. An image forming apparatus which forms a latent image on an image carrier, develops the latent image with a powder developer, and executes image formation. An image forming apparatus, wherein the developing means for developing with the developer is the developing device according to any one of claims 1 to 6.