JP2000112227A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of obtaining an excellent output image by preventing the output image quality from lowering in consequence of the temp. rising, even though successively carrying out the image output with high speed. SOLUTION: In this image forming device 4 provided with a developing vessel (developer containing means) 41 containing the powdered developer, a developing sleeve (developer carrying means) 42 in a roller shape supported by the developing vessel 41 freely rotatably, for carrying the developer on its surface, and a doctor blade (developer layer controlling member) 43, the device is provided with a first heat radiating means 49 equipped with a fin 49a on an end part of the developing sleeve 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing apparatus for developing an electrostatic latent image formed on an image carrier by an electrophotographic system or an electrostatic recording system with a powdery developer, and more particularly to a developing container. The present invention relates to a developing device which is rotatably supported by a device and has developer carrying means for carrying and transporting the developer on the surface.

[0002]

2. Description of the Related Art Conventionally, a copier, a printer, a facsimile, and other image forming apparatuses for forming an image by an electrophotographic system or the like carry an electrostatic latent image formed through a predetermined process as shown in FIG. The developer carrying means 42 of the developing device 4 is disposed at a fixed interval G1 with respect to the image carrier 1 such as a photosensitive drum for performing the image forming operation. The electrostatic latent image on the body 1 was developed.

As a method of forming a developer layer on a developer carrying means for performing the above-mentioned development, a plate-like member 43 as a developer thin layer forming means is attached to the developer carrying means 42 as shown in FIG. Method of contacting with appropriate pressure, and FIG.
As shown in FIG. 1, there is known a method in which the developer carrying means 42 is disposed at an appropriate interval G1, and the developer is sent to a portion N close to the plate member 43 by rotation of the developer carrying means 42.

[0004]

However, in the conventional developing device, when image output is continuously performed without providing an appropriate pause interval, various output image qualities mainly focusing on image density reduction are obtained. There has been a problem of causing a decrease. The main cause is considered to be the deterioration of the developer due to an increase in the temperature inside the developing device and the image forming apparatus due to eddy current due to rotation of the developer carrying the magnetic field generating means and friction with the developer.

FIG. 13 shows a normal temperature and normal humidity (about 23 ° C., 50% R).
H, the same applies hereinafter), showing the relationship between the temperature of the doctor blade of the developing device and the image reflection density, and from this figure, it can be seen that the image reflection density decreases when the temperature of the developing device rises. I understand. Here, the image reflection density refers to the United States
This is the average of the values obtained by measuring five points in a portion where a circular original having a reflection density of 1.2 and having a diameter of 5 mm and having a diameter of 5 mm appeared on the copied image using an image reflection densitometer RD-914 manufactured by MacBeth Co. the same).

[0006] The above-mentioned problem is becoming more and more serious in today's world where the speed of image formation and the number of processing units are required to be increased with the development of the network environment.

[0007] Certainly, a Peltier element (a device whose temperature is lowered on one side and heated on the other side when a current is applied, and is also called a semiconductor heat pump. It is used for temperature compensation of semiconductor lasers and the like that are severe in temperature. ) May be used, but the disadvantage of this device is that it is expensive.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object thereof is to prevent a decrease in output image quality due to a rise in temperature even when image output is performed at high speed and continuously. It is an object of the present invention to provide a developing device capable of obtaining a desired output image.

[0009]

In order to achieve the above object, the invention according to claim 1 comprises a developer accommodating means for accommodating a powder developer, and a rotatable support for the developer accommodating means. In a developing device having a roller-shaped developer carrying means for carrying a developer and a developer layer thickness regulating member, a first heat radiating means having a fin at an end of the developer carrying means is provided. Features.

According to a second aspect of the present invention, in the first aspect of the present invention, the first heat radiating means is arranged in an airflow moving in a substantially constant direction.

According to a third aspect of the present invention, in the first aspect of the invention, all or a part of the first heat radiating means generates an air flow moving toward the developer accommodating means. And

According to a fourth aspect of the present invention, in the first, second or third aspect, the first heat radiating means is made of an alloy containing aluminum.

According to a fifth aspect of the present invention, in the first aspect of the invention, a second heat radiation means made of an alloy containing aluminum is joined to the developer layer thickness regulating member;
The second heat radiating means is exposed on the surface.

[0014]

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

<Embodiment 1> FIG. 1 is a side sectional view of a developing device according to the present invention, FIG. 2 is a sectional view taken along line XX of FIG. 1, FIG. 3 is a front view of a developing sleeve, and FIG. 5 is a perspective view of the developing device according to the present invention, FIG. 6 is a waveform diagram of the developing bias, FIG. 7 is a side view of the developing device, and FIG. 8 is a view of the doctor blade and the second radiating device. It is a perspective view which shows the positional relationship at the time of an assembly.

The developing device 4 shown in FIG. 1 is provided with a rotatable developing sleeve 42 as a developer carrying means at an opening facing the image carrier 1 in a developing container 41 as a developer accommodating means. The developing sleeve 42 is disposed at a predetermined interval G1 between the developing sleeve 42 and the image carrier 1.

The developing sleeve 42 has a diameter of 32.3 m.
m, a hollow cylinder made of an aluminum alloy A6063 having a length of 325 mm, and a clutch and gear 4 (not shown) provided by a motor (not shown) provided in the main body of the image forming apparatus.
5 (see FIG. 2) in the direction of arrow A in FIG.
It is driven to rotate at a speed of 5 mm / sec. The outer surface of the developing sleeve 42 has an initial thickness of 10 to 14 which is 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 set to 0.40 to 0.60 μm Ra by sanding or the like.

As shown in FIG. 3, hollow flanges 42f and 42r made of aluminum alloy A2011 are press-fitted at both ends of the developing sleeve 42, and the first heat radiating means is inserted into the front flange 42f of the image forming apparatus. 49 are attached.

The first heat radiating means 49 has a basic diameter of 35 mm.
The outer periphery of which is provided with twelve fins 49a having a thickness of about 1 mm and arranged at regular intervals at an angle of 30 ° to each other. These fins 49
The outer diameter of the first heat radiating means 49 including a is 50 mm.

Each of the fins 49a is attached at a predetermined twist angle with respect to the cylindrical generatrix.
Rotation in the direction of arrow A in FIG. 1 generates an airflow moving at a speed in the direction of arrow C in FIG. It is desirable that the first heat radiating means 49 be made of a metal having high thermal conductivity.
The same aluminum alloy A2011 as f is used.

As shown in FIG. 5, the first heat radiating means 49 is disposed in a duct 61, and is exposed to an air flow V (at a speed of 2 to 3 m / sec) generated by fans 62 and 63.

Incidentally, the developing sleeve 42 and the image carrier 1
The distance G1 between the spacer rollers 43f and 43 shown in FIG.
r, the amplitude is maintained between 180 and 220 μm, and between them, the amplitude Vpp = 900-1100 V, the frequency f = 1 / T = 2
A rectangular wave AC voltage having a frequency of 650 to 2750 Hz and a duty ratio η = 0.4 is superimposed on a DC voltage VDC that can be varied between 0 and 600 V (see FIG. 6). Here, the duty ratio η is a value obtained as Tdev // T.
Tdev is the time for the developer to fly from the developing sleeve 42 to the image carrier 1.

Further, as shown in FIG.
A magnet roller 46 made of ferrite as a magnetic field generating means is fixedly installed inside. On the surface of the magnet roller 46, a developer pumping pole S3 and a developing pole N
A total of six magnetic poles N1 to N3 and S1 to S3 are provided.

The developer attracted to the surface of the developing sleeve 42 by the developer pumping pole S3 of the magnet roller 46 and the like is disposed with a predetermined interval G2 between the developer and the developing sleeve 42. The thickness is reduced by the interaction between the SPCC rectangular doctor blade 43 having a thickness of 1 mm and the developer layer thickness regulating electrode N1. Note that the interval G2 is 210 to
It is set to 250 μm.

The average charge amount of the developer on the developing sleeve 42 at normal temperature and normal humidity is +8 to +12 μC / g, and the coating amount is 0.7
０．９0.9 mg / cm ² .

As the developer, a styrene-acrylic binder resin, magnetite as a magnetic material, silica as a fluidizing agent, strontium titanate as an abrasive, etc. are appropriately mixed, and the initial weight average particle size thereof is used. Is 7.
5 to 8.0 μm.

At the front end of the doctor blade 43, a second radiating means 43a made of an aluminum alloy A2011 as shown in FIGS. 2, 7 and 8 is attached. The second heat radiating means 43a is attached to the developing container 41 together with the doctor blade 43 by screws 50 as shown in FIG.

A part of the second heat radiating means 43a is formed in a fin shape, and the second heat radiating means 43a is arranged in the duct 61 similarly to the first heat radiating means 49 as shown in FIG. And is exposed to an air flow V (at a speed of 2-3 m / sec) generated by the fans 62 and 63.

The heat taken from the first heat radiating means 49 and the second heat radiating means 43a is discharged outside the image forming apparatus. That is, the heat generated by the rotation of the developing sleeve 42 is transferred to the first and second radiating means 4 provided in the developing device 4.
9, 43a makes it possible to escape efficiently,
The temperature rise of the developing device 4 can be suppressed.

In the developing device 4 according to the present embodiment, the temperature at the center of the doctor blade 43 was 25 ° C. when the room temperature and normal humidity were saturated.

Table 1 shows the change in image density and the relative value of the apparatus cost when a standard density original is continuously 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. According to this, the superiority of the developing device according to the present embodiment can be understood.

[0032]

<Embodiment 2> Next, Embodiment 2 of the present invention.
Will be described.

The developing device according to the present embodiment is the same as the developing device 4 according to the first embodiment except that the duct 61 shown in FIG. 5 is omitted.

According to Table 1, the performance is slightly inferior to that of the first embodiment, but the cost is low, and the superiority of the developing device according to the present embodiment is higher than that of the conventional examples 1 and 2 described later. It can be understood.

Third Embodiment Next, a developing device according to a third embodiment of the present invention will be described.

In the developing device according to the present embodiment, since the fins 49a of the first heat radiating means 49 shown in FIG. 4 are attached parallel to the cylindrical generatrix, air flows in the direction of arrow C in FIG. This is the same as the developing device 4 according to the first embodiment except that no flow occurs.

According to Table 1, although the performance is slightly inferior to the first embodiment, the cost is low, and it is understood that the developing device according to the present embodiment is superior to the conventional examples 1 and 2 described later. it can.

<Fourth Embodiment> Next, a developing device according to a fourth embodiment of the present invention will be described.

The developing device according to the present embodiment is the same as the developing device 4 according to the first embodiment except that the material of the first heat radiating means 49 is a polyacetal resin.

Although the polyacetal resin has poor thermal conductivity,
There is an advantage that the manufacturing cost of the heat radiating means 49 is greatly reduced.

According to Table 1, the performance is slightly inferior to the first embodiment, but the cost is low, and it is understood that the developing device according to the present embodiment is superior to the first and second prior art examples described later. it can.

<Fifth Embodiment> Next, a developing device according to a fifth embodiment of the present invention will be described.

The developing device according to the present embodiment is the same as the developing device 4 according to the first embodiment except that it does not include the second heat radiation means 43a attached to the doctor blade 43.

According to Table 1, although the performance is slightly inferior to the first embodiment, the cost is low, and it is understood that the developing device according to the present embodiment is superior to the first and second conventional examples described later. it can.

<Sixth Embodiment> Next, a developing device according to a sixth embodiment of the present invention will be described with reference to FIG.

The developing device according to the present embodiment is the same as the developing device 4 according to the first embodiment except that a heat radiating means 49 'is provided on the back side.

Here, the direction of the heat radiating fins of the heat radiating means 49 'is opposite to that of the heat radiating fins 49 on the front side, and an air flow is generated in the direction of arrow C'. The heat radiating means 49 is the same as that shown in the first embodiment.

According to Table 1, although the performance is slightly inferior to that of the first embodiment, the cost is low, and it is understood that the developing device according to the present embodiment is superior to the conventional examples 1 and 2 described later. it can.

<Conventional Example 1> A developing device according to this conventional example is
All cooling / radiating means (radiating means at the end of the developing sleeve,
It is the same as the developing device 4 according to the first embodiment except that it does not include a heat radiation means, a cooling fan, and a cooling duct at the front end of the doctor blade.

In the developing device according to this conventional example, the temperature at the center of the doctor blade was 49 ° C. when the room temperature and normal humidity were saturated.

According to Table 1, it can be understood that the cost is lower than that of the first embodiment, but the performance is remarkably inferior.

<Conventional Example 2> The developing device according to the conventional example is
This is the same as the developing device 4 according to the first embodiment except that a Peltier element 401 is provided as a cooling unit as shown in FIG.

The Peltier element 401 is formed by alternately joining an n-type semiconductor such as Bi-Te and a p-type semiconductor such as Bi-Te by soldering.
The heating surface 40 has a square shape of mm square.
A radiation fan 402 is attached to 1b, and a heat absorption surface 401a is attached to a central portion in the longitudinal direction of the doctor blade 43. The maximum heat absorption of the Peltier element 401 is about 80 W.

According to Table 1, the developing device according to the conventional example is certainly satisfactory in performance, but is inferior overall to the developing device 4 according to the first embodiment in consideration of cost. Can be understood.

Although the present invention has been described with reference to the case of using a magnetic one-component developer, the technical scope of the present invention is not limited to this. For example, a developing unit having two or more developer carrying units in one electrostatic latent image carrying unit, a developing unit employing a method of contacting the developer carrying unit as a developer regulating unit, not only a developer carrying unit, Developing means or the like in which the magnetic field generating means included in the developer carrier rotates together, in other words, all changes recognized as small changes in light of the spirit of the present invention are included in the technical scope of the present invention. Things.

Further, the present invention is applied to a developing device having two or more developer carriers, a developing device having a cylindrical developer carrier, a developing device using a two-component developer composed of a toner and a carrier, and the like. The invention is applicable.

When performance is prioritized over cost,
As a material of the heat radiating means at the end of the developer carrier and the heat radiating means at the front end of the doctor blade, a metal having high heat conductivity such as zinc, aluminum, tungsten, copper, magnesium, beryllium or molybdenum may be contained.

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

[0059]

As is apparent from the above description, according to the present invention, the developer accommodating means accommodating the powder developer, and the developer accommodating means are rotatably supported by the developer accommodating means. In a developing device having a roller-like developer carrying means for carrying and a developer layer thickness regulating member, a first heat radiating means having a fin at an end of the developer carrying means is provided, so that image output can be performed at high speed. In addition, even when the printing is performed continuously, a high-quality output image can be obtained by preventing the output image quality from deteriorating due to a temperature rise.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a developing device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a front view of a developing sleeve of the developing device according to the first embodiment of the present invention.

FIG. 4 is a perspective view of a first heat radiation unit of the developing device according to the first embodiment of the present invention.

FIG. 5 is a perspective view of the developing device according to the first embodiment of the present invention.

FIG. 6 is a waveform diagram of a developing bias in the developing device according to the first embodiment of the present invention.

FIG. 7 is a side view of the developing device according to the first embodiment of the present invention.

FIG. 8 is a perspective view showing a positional relationship when assembling the doctor blade and the second heat radiation means of the developing device according to the first embodiment of the present invention.

FIG. 9 is a view similar to FIG. 2 of a developing device according to a sixth embodiment of the present invention.

FIG. 10 is a side sectional view of a developing device according to Conventional Example 2.

FIG. 11 is a side sectional view of a conventional developing device.

FIG. 12 is a side sectional view of a conventional developing device.

FIG. 13 is a diagram showing the relationship between the temperature of a doctor blade and the image reflection density of an output image.

[Explanation of symbols]

 Reference Signs List 4 developing device 41 developing container (developer accommodating means) 42 developing sleeve (developer carrying means) 43 doctor blade (developer layer thickness regulating member) 43a second heat radiating means 49 first heat radiating means 49a fin

[Table 1]

Claims (5)

[Claims] 1. A developer accommodating means for accommodating a powder developer, a roller-shaped developer carrying means rotatably supported by the developer accommodating means and carrying the developer on the surface, and a developer layer thickness. A developing member having a regulating member and a first heat radiating means having a fin at an end of the developer carrying means. 2. The apparatus according to claim 1, wherein said first heat radiating means is disposed in an airflow moving in a substantially constant direction.
The developing device as described in the above. 3. The whole or a part of the first heat radiation means,
2. The developing device according to claim 1, wherein an air flow moving toward the developer accommodating means is generated. 4. The first heat radiating means is made of an alloy containing aluminum.
The developing device as described in the above. 5. A method according to claim 1, wherein a second heat radiation means made of an alloy containing aluminum is joined to said developer layer thickness regulating member, and said second heat radiation means is exposed on the surface. The developing device according to claim 1.