JP2002182519A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high quality output images for a long time by preventing image quality degradation which is caused by a rise in the temperature of a developing device. SOLUTION: Information on temperature in the vicinity of the developing device 3, measured by a temperature sensor 30, is input to a controller 31. Based on the inputted temperature information, a controller 31 controls energization of a halogen heater 8 of a fixing device 8, thereby adjusting heat generation temperature of the halogen heater 8. The control makes it possible to restrain a rise in the temperature of the developing device 3 during image formation. Consequently, degradation in image quality which results from the temperature rise of the developing device 3, is prevented, and the outputs of high quality images can be ensured for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, etc., which forms an image using an electrophotographic system or an electrostatic recording system.

[0002]

2. Description of the Related Art As shown in FIG. 15, for example, an image forming apparatus such as a copying machine, a printer, a facsimile or the like using an electrophotographic system is a drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) as an image carrier. ) 100 and 1 around it
Next charger 101, developing device 102, transfer charger 103,
A cleaning device 104 is provided. An exposure device 1 is located above the primary charger 101 and the developing device 102.
05 is installed.

In the image forming apparatus having the above-described configuration, the photosensitive drum 100 is driven by a driving unit (not shown) when an image is formed.
, The surface is uniformly charged by the primary charger 101 to which the charging voltage is applied. Then, an image exposure L by a laser beam is given from the exposure device 105 to the charged photosensitive drum 100 to form an electrostatic latent image corresponding to the input image information. The toner is developed as a toner image by 102 and is visualized.

Then, the toner image formed on the photosensitive drum 100 is transferred to a transfer material P such as paper by a transfer charger 103 to which a transfer voltage is applied in a transfer portion N, and the toner image is transferred. The transfer material P is conveyed to a fixing device (not shown), and the toner image is fixed on the transfer material P by the fixing device and discharged. Note that the transfer residual toner remaining on the photosensitive drum 100 after the fixing is removed by the cleaning device 104.

[0005] By the way, as a developing method by the developing device 102 described above, a toner and a carrier are mainly used.
The magnetic brush development method using a component developer has been widely put into practical use. However, this method can obtain a relatively stable and good image, but has a two-component development method in which the carrier deteriorates and the mixing ratio of the toner and the carrier fluctuates. It has disadvantages related to the agent.

In order to avoid such disadvantages, various developing methods using a one-component developer consisting of toner alone have been proposed. According to this developing method, there is no need to control the mixing ratio of the toner to the carrier, so that there is an advantage that the developing device is simplified. In this one-component developing method, as shown in FIG. 15, a developing sleeve 106 as a developer carrying member of a developing device 102 is disposed in a non-contact manner with respect to a photosensitive drum 100 carrying an electrostatic latent image. By applying a developing voltage between the drum 100 and the developing sleeve 106, the electrostatic latent image formed on the photosensitive drum 100 is developed.

In order to perform the above-described development, a method of forming a thin developer layer on the developing sleeve 106 is as follows.
As shown in FIG. 16, as a developer layer forming means, a regulating blade 107 made of a plate-like member is brought into contact with a developing sleeve 106 with an appropriate pressure, or as shown in FIG.
A regulating blade 108 made of a plate-shaped member is provided at an appropriate distance from the developing sleeve 106.

In both cases, the toner t as the developer is fed between the developing sleeve 106 and the regulating blade 107 or 108 by the rotation of the developing sleeve 106 in the direction of the arrow (counterclockwise), and the developing sleeve The developing sleeve 106 is fixed by a magnet roller 109 as a fixed magnetic field generating means incorporated in the developing sleeve 106.
Magnetically restrained on top.

As a fixing device for fixing an unfixed toner image on a transfer material, there are a method of heating while applying pressure, a method of heating without applying pressure, and a method of applying ultraviolet rays or the like. In the above method of heating while applying pressure,
As shown in FIG. 18, a fixing device 110 that sandwiches a transfer material P at a fixing nip between a fixing roller 111 having a heater 112 and a pressure roller 113, or a heater 116 as shown in FIG. Film fixing member 115
There is a fixing device 118 that sandwiches the transfer material P at a fixing nip between the transfer material P and the pressure roller 117.

[0010] By the way, with the recent increase in resource saving consciousness, the proportion of users who print (image formation) only on one side of the printing paper (transfer material) as a toner image carrying medium as in the related art has decreased. However, the ratio of users who print on both sides is increasing.

Conventionally, as a method of performing continuous printing on both sides of a transfer material such as a plurality of sheets of paper (hereinafter, this operation is referred to as double-sided continuous printing), first, a continuous printing is performed on one side of a plurality of transfer materials. The toner image is transferred and fixed (hereinafter, this operation is referred to as single-sided printing), and a plurality of transfer materials are temporarily stacked on the intermediate tray serving as a stacking unit, and the transfer material is temporarily transferred to the entire number of transfer materials. A method of continuously transferring and fixing a toner image to the other surface of each transfer material stacked on the intermediate tray at the same time or almost simultaneously with the completion of one-side printing, or after a predetermined time (hereinafter, this method is referred to as a stacking method). System) was the mainstream.

However, in the above loading method,
A space for providing the intermediate tray inside or outside the image forming apparatus is required, and the transfer material printed on one side is temporarily loaded on the intermediate tray until one-side printing on all the transfer materials is completed. Therefore, there is a limit in shortening the time required for image formation, and it has been difficult to respond to high-speed image formation.

In view of the above, instead of the above-mentioned stacking method, paper feeding means for feeding a transfer material toward a transfer portion formed between the photosensitive drum and the transfer device, and a toner image on one surface of the transfer portion A reversing means for reversing the transfer material on which the transferred and fixed transfer material is transferred to the other surface and re-transporting the transfer material toward the transfer portion, and conveyed from either the paper feeding means or the reversing means. Irrespective of the transfer material to be transferred, a method of performing continuous printing on a plurality of transfer materials in the order of arrival at the transfer portion (hereinafter, referred to as
Through-path method) has been proposed. In recent years, an image forming apparatus having this through-pass method has been put to practical use, and it has become possible to reduce the size of the image forming apparatus and to increase the speed of outputting double-sided images.

[0014]

By the way, in the above-mentioned conventional image forming apparatus, especially in the above-mentioned digital image forming apparatus of the through-pass type which has a high image output speed, for example, the image output is performed without providing an appropriate pause interval. In some cases, for example, the image quality is lowered due to a decrease in image density.

The main causes are heat due to eddy current due to rotation of a developing sleeve having a fixed magnet roller built therein as in the above-described developing device, frictional heat with toner, and a heating element of a fixing device. It is considered that the temperature of the developing device rises due to the heat generated by the halogen heater) and the like, and the quality of the toner mainly composed of resin is changed.

FIGS. 20A and 21C show the output of an A4-size standard image ratio (about 6%) of a double-sided printed image at normal temperature and normal humidity (temperature 23 ° C., humidity 50% RH). FIG. 4 shows the transition of the temperature of the regulating blade and the image reflection density of the developing device in the conventional example when 20,000 pages are continuously performed from the start of the device. It can be seen that the reflection density has decreased. As described above, the developing device including the regulating blade has heat generated by eddy current due to rotation of the developing sleeve having a built-in magnet roller, frictional heat with toner, and heat generated by the heating element (halogen heater) of the fixing device. Increases the temperature.

FIGS. 20b and 21d show the output of a double-sided printed image of an A4 size standard image ratio (about 6%) at normal temperature and normal humidity (temperature 23 ° C., humidity 50% RH).
When performing 20,000 pages continuously from the start of the image forming apparatus,
FIG. 3 shows the transition of the temperature of the regulating blade of the developing device and the transition of the image reflection density in the first embodiment of the present invention, which will be described later.

The image reflection density in FIG.
This is the average value of the values obtained by measuring five points in a portion where a circular original having a image reflection density of 1.2 and a diameter of 5 mm appeared on the output image using an image reflection densitometer RD-914 manufactured by acBeth.

In the case of the two-sided continuous printing in the above-described through-pass system, the transfer material is a fixing device, for example, a fixing nip portion between the fixing roller 111 and the pressure roller 113 of the fixing device 110 shown in FIG. Immediately after passing, that is, immediately after the printing on the first surface is completed, the transfer material having a high temperature returns to the transfer portion, and the heat radiated causes the temperature of the developing device to rise.

In the through-pass method, the temperature of the transfer material may not be expected to decrease during the accumulation in the intermediate tray as in the above-described stacking method. The temperature rise of the developing device is larger than in the case of the loading system having the intermediate tray. FIG. 22 shows that A4 at normal temperature and normal humidity (temperature 23 ° C., humidity 50% RH).
This graph shows the transition of the temperature of the regulating blade in the developing device when a double-sided printed image having a standard image ratio of the size (about 6%) is continuously output for 20,000 pages from the start of the image forming apparatus. is there. FIG. 22E shows the case of the through-pass system without the intermediate tray, and FIG. 22F shows the case of the loading system with the intermediate tray. In the case of the through-pass system without the intermediate tray, the temperature of the regulating blade rises. .

Further, since the fixing device, which is the largest heat source in the image forming apparatus, has a heating element (halogen heater), the amount of heat generated by the heating element increases to increase the temperature of the developing device. As described above, the largest factor in the temperature rise of the developing device during image formation is heat generated by the heating element (halogen heater) of the fixing device, and the image quality deteriorates due to the temperature rise of the developing device due to the heat generated by the heating element. There was a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of preventing deterioration in image quality due to a rise in the temperature of a developing device and providing a high-quality output image for a long period of time.

[0023]

According to the first aspect of the present invention, a developer is attached to an electrostatic latent image formed on an image carrier, and is visualized as a developer image. Developing means, a transferring means for transferring the developer image to a transfer material, a pair of fixing members and a pressing member, and a heating element provided at least in one of the fixing member and the pressing member. Fixing means for fixing the developer image by heating and pressing the transfer material between the fixing member and the pressing member due to heat generated by the heating element; and at least one of the transfer material. An image forming apparatus that heats and fixes a developer image on a surface of the image forming apparatus, and discharges the image after the fixing, and a temperature measuring unit that measures a temperature near the developing unit; and a temperature near the developing unit measured by the temperature measuring unit during image formation. Based on the information It is characterized by having a control means for regulating the heating temperature of the heating body by controlling the energization of the heating body of the stage.

A developing means for adhering a developer to the electrostatic latent image formed on the image carrier to visualize it as a developer image; a transfer means for transferring the developer image to a transfer material;
A pair of fixing members and a pressure member, a heating element provided at least inside one of the fixing member and the pressure member, and a pressure for pressing the fixing member and the pressure member to abut against each other. Fixing means for fixing the developer image by heating and pressing the transfer material between the fixing member and the pressing member by pressurization by the pressing means and heat generated by the heating element. An image forming apparatus that heats and pressurizes and fixes a developer image on at least one surface of the transfer material and discharges the image after the fixing, and a temperature measuring unit that measures a temperature near the developing unit; Based on the temperature information near the developing unit measured by the measuring unit, the power supply to the heating unit of the fixing unit is controlled to adjust the heat generation temperature of the heating unit, and the pressing force of the pressurizing unit is controlled. And the fixing member It is characterized by having a control means for adjusting the contact force between the pressure member, the.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment.

<Embodiment 1> FIG. 1 shows an image forming apparatus according to Embodiment 1 of the present invention (in this embodiment, an image forming apparatus such as a digital monochrome copying machine capable of single-sided printing and double-sided printing). FIG. 2 is a schematic configuration diagram illustrating a (forming apparatus).

The present image forming apparatus includes a photosensitive drum 1 as an image carrier that is driven to rotate in the direction of arrow a (clockwise). Around the photosensitive drum 1, a primary charger 2,
A developing device 3, a transfer charger 4, a separation charger 5, and a cleaning device 6 are provided, and the primary charger 2 and the developing device 3
Exposure device 7 is provided above the space between them. Also,
A fixing device 8 is provided downstream of the transfer section N in the transfer direction of the transfer material P between the photosensitive drum 1 and the transfer charger 4.

The photosensitive drum 1 has an a-Si (amorphous silicon) photosensitive layer on a cylindrical drum base made of aluminum or the like, and has an outer diameter of 108 mm. The photosensitive drum 1 is driven by driving means (not shown).
Accordingly, it is rotationally driven in the direction of arrow a (clockwise) at a predetermined rotational speed (450 mm / sec in the present embodiment).

In the present embodiment, the primary charger 2 as a charging means uniformly charges the surface of the photosensitive drum 1 to a predetermined positive potential with corona ions generated by corona discharge when a charging voltage is applied.

The developing device 3 includes a rotatable developing sleeve 2.
And a toner as a developer is attached to the electrostatic latent image formed on the photosensitive drum 1 at the developing position, and the toner image is subjected to reverse development (visualization) (developing device 3 Will be described later).

The transfer charger 4 serving as a transfer unit is provided at a transfer portion N between the photosensitive drum 1 and the transfer charger 6 by a transfer voltage applied from a transfer power supply (not shown).
The toner image on the surface is transferred to a transfer material P such as paper.

The separation charger 5 includes a separation charging power source (not shown).
The transfer material P on which the toner image has been transferred is separated from the surface of the photosensitive drum 1 by the separation charging voltage applied from.

The cleaning device 6 has a cleaning blade 6a, and removes and collects the transfer residual toner remaining on the surface of the photosensitive drum 1 after the transfer by the cleaning blade 6a.

The exposure device 7 receives image information of a document (not shown) read by a scanner unit (not shown), and modulates the laser information corresponding to the time-series electric digital image signal of the inputted image information. Light is output from a semiconductor laser (not shown), the laser light is scanned by a polygon mirror (not shown) rotating at high speed, and the surface of the charged photosensitive drum 1 is subjected to image exposure L, thereby responding to an image signal. An electrostatic latent image is formed.

The fixing device 8 includes a fixing roller 8a and a pressure roller 8b.
While nipping and transporting the transfer material P in the fixing nip between
The unfixed toner image transferred to the surface of the transfer material P is heated and pressurized and thermally fixed (the details of the fixing device 8 will be described later).

Next, an image forming operation by the above-described image forming apparatus will be described.

At the time of image formation (single-sided printing), the photosensitive drum 1 is rotationally driven by a driving means (not shown) in the direction of arrow a at a predetermined rotational speed (450 mm / sec in the present embodiment). As a result, the surface is uniformly charged to a predetermined positive potential (approximately +400 V). The image exposure L by the laser beam is given to the charged surface of the photosensitive drum 1 by the exposure device 7, so that the potential of the surface of the photosensitive drum 1 is reduced at the portion where the image exposure L is performed. An electrostatic latent image corresponding to the image information (not shown) is formed.

A developing sleeve in which a developing voltage having the same polarity as the charging polarity (positive in this embodiment) of the photosensitive drum 1 is applied to the electrostatic latent image formed on the surface of the photosensitive drum 1 at the developing position. By 22, the toner charged to the same polarity as the charged polarity (positive polarity) of the photosensitive drum 1 is adhered, and the toner image is reversely developed (developed).

When the toner image on the surface of the photosensitive drum 1 reaches the transfer section N between the photosensitive drum 1 and the transfer charger 4, the sheet cassettes 10 and 1 are synchronized with this timing.
A transfer material P such as paper of a predetermined size, which is selected and fed from the tray 1 or 12 or the manual feed tray 14, is conveyed to the transfer portion N by the registration roller pair 17, and a transfer voltage having a polarity opposite to that of the toner is applied. The toner image on the surface of the photosensitive drum 1 is transferred to the transfer material P by the transfer charger 4.

In the sheet cassettes 10, 11, and 12, transfer materials P such as sheets of different sizes are stored, and the transfer materials P are supplied to the respective sheet feed rollers 13a, 13b,
The sheet is fed one by one by 13c, and is conveyed to the registration roller pair 17 through the conveyance guide 16 by the conveyance rollers 15a, 15b, 15c. The manual tray 14 can store a transfer material of any size, and is conveyed to the registration roller pair 17 by the paper feed roller 13d.

Then, the transfer material P on which the toner image has been transferred is separated from the photosensitive drum 1 by the separation charger 5, and the fixing device 8
And is nipped and conveyed by a fixing nip between the fixing roller 8a and the pressure roller 8b of the fixing device 8. The transfer material P on which the toner image has been transferred is heated and pressed by a fixing nip between a fixing roller 8a having a built-in halogen heater 9 and a pressure roller 8b, and the toner image is thermally fixed on the surface of the transfer material P. ,
It is discharged to the outside by the forward rotation of the reversing roller 18.

On the other hand, the transfer residual toner remaining on the surface of the photosensitive drum 1 after the transfer of the toner image is removed and collected by the cleaning blade 6a of the cleaning device 6. In addition, the residual charges on the surface of the photosensitive drum 1 are removed by a pre-exposure device (not shown), and are prepared for the next image formation.

During double-sided printing, after the image formation on the first side of the transfer material P has been completed by the above-described single-sided printing operation and has been fixed by the fixing device 8, the reverse rotation of the reversing roller 18 causes the re-feeding belt 19 Transported to Then, the transfer material P conveyed onto the re-feeding belt 19 is again transferred to the transfer portion N between the photosensitive drum 1 and the transfer charger 4 at a predetermined timing.
After the image is formed on the other surface on which the toner image is not transferred in the same manner as described above, the image is discharged to the outside.

Next, the developing device 3 in the present embodiment will be described in detail.

As shown in FIG. 2, the developing device 3 of the present embodiment includes a developing container 2 containing a toner t as a developer.
1, a developing sleeve 22 that is driven to rotate in the direction of the arrow (counterclockwise), a magnet roller 23 fixedly disposed in the developing sleeve 22, and a toner t on the surface of the developing sleeve 22 with an appropriate distance from the developing sleeve 22. A regulating blade 24 made of a plate-like member arranged to form a thin layer of the toner, stirring members 25, 26 and 27 for stirring and transporting the toner t, a piezoelectric element 28 for detecting the amount of the toner t, and the like. Approximately 250 g of toner t is stored in the developing container 21 in a steady state.

The developing sleeve 22 is disposed with a predetermined gap (200 μm in the present embodiment) provided between the photosensitive drum 1 and the developing sleeve 22 at a rotational speed (450 mm / sec) of the photosensitive drum 1 by driving means (not shown). It is rotated in the direction of the arrow (counterclockwise) at a high speed (787.5 mm / sec in the present embodiment). Developing sleeve 22 and photosensitive drum 1
The developing voltage having the same polarity as the charging polarity (positive in this embodiment) of the photosensitive drum 1 is applied from the developing power supply 29 to the same, and the charging polarity is charged to the same polarity as the charging polarity (positive) of the photosensitive drum 1. The applied toner t is adhered and reversal development (visualization) is performed as a toner image.

In the present embodiment, the developing voltage applied to the developing sleeve 20 from the developing power supply 29 has an amplitude Vpp: 1
000 V, frequency f: 2.7 kHz, duty ratio:
This is a voltage obtained by superimposing a DC voltage of 280 V on an AC voltage of 0.4.

By the developing operation, the toner t in the developing container 21 is
Decreases, the piezoelectric element 28 detects the decrease in the toner t.
, The mag roller 33 rotates, and the toner t is supplied from the toner supply device 32 into the developing container 21. Further, as shown in FIG. 3, the toner t is stored in a toner storage container 43 in which the stirring and conveying members 41 and 42 are built.
It is supplied to a user or the like in a state where 0 g is filled. And
The toner t filled in the toner supply device 32
Is empty, the toner is replaced with an empty toner storage container, and the new toner storage container 43 is mounted on the toner supply device 32 to supply toner.

The toner t as a developer used in the present embodiment is a one-component magnetic toner in which magnetic particles are dispersed in a resin. This toner t has positive chargeability, and has a weight average particle size of about 8.0 μm.

The particle size distribution of the toner t can be measured by various methods. In this case, a counter TA-II (trademark) manufactured by Coulter Co., USA is used, and 1% NaC
l Several drops of a surfactant in an aqueous solution
Was ultrasonically dispersed for several minutes, and the particle size distribution of 2 to 40 μm particles was counted through a 100 μm aperture.

The binder resin of the toner t generally includes a styrene-based styrene-acryl copolymer, a styrene-butadiene copolymer, a phenol resin, a polyester, and the like. Here, a styrene acrylic copolymer and a styrene butadiene copolymer were used in a ratio of 8: 2. Also,
Nigrosine, quaternary ammonium salts, triphenylmethane, imidazole and the like are used for the positive toner as the charge control agent (usually added internally to the toner, but external addition is also possible). Here, triphenylmethane (resin component 100
2 parts). Since the toner t in the present embodiment is a magnetic toner, iron oxide such as magnetite and ferrite is dispersed therein.
Parts are common.

The external additive to the toner t is mainly silica for imparting fluidity, and is externally added in an amount of about 0.1 to 5 parts by weight.
The silica has a function of reducing the abrasion of the developing sleeve 22 by interposing between the toner particles and the developing sleeve 22, further preventing aggregation of toner particles,
There is also a role to promote the exchange of the toner in contact with the toner in contact with the toner 2.

In some cases, strontium titanate, cerium oxide, praseodymium oxide, lanthanum oxide, neodymium oxide, or the like is externally added to the toner t. They are,
It functions as an abrasive for the photosensitive drum 1 and has an effect of polishing and removing toner adhering to the photosensitive drum 1 in the form of a film.

The initial average charge amount of the toner t on the developing sleeve 22 at normal temperature and normal humidity is +6 to +12 μC / g, and the coating amount is 0.7 to 0.9 mg / cm ² .

In the case of the toner for heat fixing as in the present embodiment, so-called wax is internally added and dispersed, and examples thereof include polyethylene, polypropylene, polyester, and paraffin.

Further, in this embodiment, the a-Si photosensitive drum is used as the photosensitive drum 1. However, since the image flow and a-Si have a temperature characteristic at the time of starting, this is prevented and the stability is maintained. For the purpose, as shown in FIG. 2, a flexible drum heater 20 for heating the photosensitive drum 1 is arranged along a peripheral surface inside the photosensitive drum 1.

Therefore, if stainless steel is used as the material of the developing sleeve 22, the drum heater 20 is likely to be deformed by heat because of low thermal conductivity. Therefore, as a material of the developing sleeve 22, it is preferable to use an aluminum alloy having a high thermal conductivity and a small thermal deformation by the drum heater 20, but the aluminum alloy is inferior in wear resistance as compared with stainless steel.

Therefore, as a method of improving the wear resistance, there are a method of coating the surface of the aluminum alloy with a resin, a method of coating with a metal plating layer, and the like.
In the present embodiment, the former is adopted.

The developing sleeve 22 in the present embodiment
As shown in FIG. 4, a resin coating layer 22b formed on a cylindrical base 22a made of an aluminum alloy is formed on the outer periphery of the base 22a by a resin composition containing a phenol resin as a binder resin 22c. However, the conductive material 22d is dispersed in the resin coating layer 22b. In some cases, a solid lubricant (not shown) may be contained together with the conductive substance.

The inventors of the present application have conducted intensive studies on the structure of the resin coating layer 22b formed on the surface of the developing sleeve 22, and as a result, as a binder resin 22c which is a film forming material, the resin itself has been compared with iron powder. It has been found that the following effects can be obtained by using a phenolic resin containing a quaternary ammonium salt compound which is positively chargeable.

That is, since the positive triboelectric charging property of the binder resin 22c itself can be improved, the charge amount of the positively chargeable toner can be maintained at a high level. It has been found that the use of the solid lubricant effectively prevents generation of toner having an excessive charge and strong adhesion of the toner to the developing sleeve 22.

The developing sleeve 2 according to the present embodiment having the above-described configuration.
No. 2 can improve the mechanical strength and abrasion resistance of the resin coating layer 22b itself, so that compared with the case where particles having a charge-imparting property are added to the toner t in order to improve the chargeability. It is also possible to endure long-term durability and to provide a good image stably for a long period of time.

In the developing sleeve 22 of the present embodiment, the binder resin 22 used when forming the resin coating layer (conductive resin (coating) layer) 22b on the surface of the developing sleeve 22
c, a resin coating layer 22 formed by using a phenolic resin containing a quaternary ammonium salt compound which is itself positively charged with respect to iron powder.
The clear reason why b is a good charge-imparting substance for a positively chargeable toner is not clear, but is considered as follows.

That is, when the quaternary ammonium salt compound itself having a positive charge property to the iron powder is used as the resin coating layer 22b, for example, when it is added to the phenol resin, it is added to the resin. Evenly distributed,
When the resin coating layer 22b is formed by heating and curing,
It is easily incorporated into the structure of the phenolic resin. At that time, the original structure of the quaternary ammonium salt having a positive polarity is lost, and the phenol resin incorporating the quaternary ammonium salt has uniform chargeability and has sufficient negative chargeability, The phenol resin having the above-mentioned compound itself is easily charged to the opposite polarity with respect to the positively chargeable toner.

As a result, it is considered that the use of the developing sleeve 22 having the resin coating layer 22b formed of such a material makes it possible to suitably charge the positively chargeable toner.

In the present embodiment, preferably used
The quaternary ammonium salt compound having the above function may be any compound as long as it is itself positively chargeable with respect to iron powder. For example, the following quaternary formula (1)
The compound represented by these is mentioned.

[0067]

Embedded image

In the above formula (1), R1, R2, R3
And R4 represent any of an alkyl group which may have a substituent, an aryl group which may have a substituent, and an alkyl group which may have a substituent.
~R4, respectively may be the or different and are identical, X ^- represents an anion.

In the general formula (1), specific examples of the anion of X ⁻ include an organic sulfate ion, an organic sulfonate ion, an organic phosphate ion, a molybdate ion, a tungstate ion, a molybdenum atom or a tungsten atom. Heteropoly acids and the like are preferably used.

The resin coating layer 2 of the developing sleeve 22 described above
2b was produced in the following manner.

First, the following materials were mixed, and zirconia particles having a diameter of 2 mm were used as a filler, followed by dispersion for 3 hours in a sand mill. The zirconia particles were separated by a sieve, and the solid content was reduced to 30% with isopropanol. A resin composition was obtained by adding a quaternary ammonium salt compound represented by the following general formula (2), which itself was positively charged with respect to iron powder, in a polyamide resin.

Carbon 20 parts by weight Graphite 80 parts by weight Phenol resin (solid content 30%) 500 parts by weight Quaternary ammonium salt compound of the following formula (2) 75 parts by weight Methanol 150 parts by weight Carbon particles (diameter 5 μm) 70 parts by weight

[0073]

Embedded image

With respect to the quaternary ammonium salt compound represented by the above formula (2), the amount of triboelectric charge with iron powder was measured by blow-off using a triboelectric charge meter (TB-200 (trademark), manufactured by Toshiba Chemical). The positive polarity was measured by the method.

The resin composition obtained above is in the form of a paint, and the composition is C (carbon) / G (graphite) / B (phenol resin) / CA (quaternary ammonium salt compound) / PC (Carbon particles) = 0.2 / 0.8 /
2.5 / 0.75 / 0.7.

Then, this resin composition was sprayed on a cylindrical body made of aluminum (substrate 22) having a diameter of 32.3 mm.
a) to form a coating (resin coating layer 22b) having a thickness of 15 to 20 μm by coating on the substrate;
By heating and curing at 30 ° C. for 30 minutes and finishing to a predetermined surface roughness with sandpaper, the developing sleeve 22 shown in FIG. 4 was obtained.

A magnetic metal regulating blade 24 for regulating the toner t to a predetermined layer thickness on the developing sleeve 22 is provided with a predetermined gap (240 μm in the present embodiment) along the longitudinal direction of the developing sleeve 22. Are located. And
In the present embodiment, as shown in FIG.
A temperature sensor 30 is attached on the back side in the longitudinal direction (rearward side perpendicular to the paper surface of FIG. 2) on the top surface 4, and measures the temperature (Tdbr) on the back side in the longitudinal direction on the regulating blade 24.

As described above, when the temperature of the developing device 3 rises due to the image forming operation, in this embodiment, the temperature rise of the developing device 3 is measured by measuring the regulating blade 24 with the temperature sensor 30. I made it.
As a result of measuring the temperature rise with respect to the number of image output pages (sheets) on the near side, the center, and the back side in the longitudinal direction of the regulating blade 24 in the direction perpendicular to the plane of FIG. 2, the result shown in FIG. 5 is obtained. Was.

That is, as shown in FIG.
4, the temperature rise increased in the order of the near side (a in FIG. 5), the central part (b in FIG. 5), and the far side (c in FIG. 5). This is due to the fact that components that generate heat, such as a motor and a power supply circuit board (not shown), are arranged behind the image forming apparatus.

The temperature sensor 30 includes a controller (CPU) 3
The control device 31 controls the energization of the halogen heater 9 of the fixing device 8 based on the temperature measurement information of the regulating blade 24 input from the temperature sensor 30, and performs the fixing at the time of fixing. The surface temperature (Trfm) of the roller 8a is set to a predetermined target temperature (Tfrmtgt) (this temperature control will be described later). Note that the control device 31 also controls the operation timing and the like of the entire image forming apparatus.

Next, the fixing device 8 according to the present embodiment will be described in detail.

The fixing device 8 in this embodiment is similar to the fixing device 8 shown in FIG.
As shown in FIG. 5, a fixing roller 8a rotated by driving a driving unit (not shown), a pressing spring 65 as a pressing unit,
66 (see FIG. 8), the pressure roller 8 b is pressed against the fixing roller 8 a and is driven to rotate, and the transfer material P such as paper on which the unfixed toner image T is transferred through the fixing entrance guide 60 is The sheet enters a fixing nip M formed by the fixing roller 8a and the pressure roller 8b. The transfer material P is nipped and conveyed by a fixing nip M between the fixing roller 8a and the pressure roller 8b, and is heated by a halogen heater 9 in the fixing roller 8a and pressurized by the fixing nip M. The upper unfixed toner image T is fixed on the transfer material P.

The transfer material P that has passed through the fixing nip M
Is the waist strength of the transfer material P itself and the fixing roller 8
a and the pressing roller 8b are separated from the fixing roller 8a and the pressing roller 8b by a fixing upper separating claw 61 and a fixing lower separating claw 62 respectively disposed on the surface of the pressing roller 8b. In the case of double-sided printing, the sheet is guided to a refeeding path.

The fixing roller 8a has an outer diameter of 60 mm and a length in the longitudinal direction of 320 mm, and is constituted by coating a coating layer 51 of a fluororesin or the like on the outer periphery of a core 50 made of hollow aluminum or the like. A halogen heater 9 as a heating means is disposed inside the gold 50. Also,
The pressure roller 8b is a roller having an outer diameter of 50 mm and a length in the longitudinal direction of 310 mm, and has a 5-mm-thick elastic layer 53 made of silicone rubber or the like formed on the outer periphery of a cylindrical metal core 52 made of stainless steel or the like. Further, a surface layer 54 is formed by coating a fluororesin or the like thereon.

Further, on the surface of the fixing roller 8a opposite to the fixing nip portion, a web 55 as cleaning means for contacting the surface of the fixing roller 8a and cleaning the surface is arranged. A web 55 formed by impregnating a nonwoven fabric with silicone oil is wound and stretched between a pair of take-up rollers 56 and 57, and is pressed against the fixing roller 8a by a pressing roller 58. The surface of the fixing roller 8a is wiped of dirt.

A temperature sensor 59 is in contact with the vicinity of the surface of the fixing roller 8a, and the fixing roller 8 is heated by the halogen heater 9 and detected by the temperature sensor 59.
The surface temperature information a is input to the control device 31 and the value of the surface temperature of the fixing roller 8a is determined. Control device 31
Controls the energization of the halogen heater 9 as described below based on the temperature measurement information of the regulating blade 24 input from the temperature sensor 30 as described above.

Next, the temperature sensor 3
Control of energization to the halogen heater 9 based on the temperature measurement information of the regulating blade 24 input from 0 will be described.

During the image forming operation, the temperature rise of the regulating blade 24 of the developing device 3 due to the heat generated by the halogen heater 9 of the fixing device 8 is measured by the temperature sensor 30, and this temperature measurement information is input to the control device 31. . Control device 3
1 performs control as shown in FIG. 7 based on the temperature measurement information input from the temperature sensor 30.

That is, the first control mode (Tfr
In the case of mtgt0i), when the temperature (Tdbr) of the regulating blade 24 is maintained at Tdbr <40 (° C.) for 5 minutes, the control device 31 determines the surface temperature (Tdbr) of the fixing roller 8a.
(rfm) is controlled to a standard value of 200 (° C.) by controlling energization of the halogen heater 9.

When the condition of 40 (° C.) ≦ Tdbr <43 (° C.) continues for 5 minutes, the controller 31 sets the target temperature (Tfrmtgt) of the surface temperature (Trfmgt) of the fixing roller 8 a to 1
The temperature is set to 95 (° C.), and the energization interval to the halogen heater 9 is lengthened, that is, the OFF time of energization to the halogen heater 9 is lengthened to lower the surface temperature of the fixing roller 8a.

When the condition of 43 (° C.) ≦ Tdbr <46 (° C.) continues for 5 minutes, the control device 31 sets the target temperature (Tfrmtgt) of the surface temperature (Trfm) of the fixing roller 8 a to 1
The temperature is set to 90 (° C.), and the energization interval to the halogen heater 9 is further extended, that is, the OFF time of energization to the halogen heater 9 is further extended to lower the surface temperature of the fixing roller 8a.

If the condition of 46 (° C.) ≦ Tdbr <48 (° C.) continues for 5 minutes, the control device 31 sets the target temperature (Tfrmtgt) of the surface temperature (Trfm) of the fixing roller 8 a to 1
The temperature is set to 80 (° C.), and the energizing interval to the halogen heater 9 is further extended, that is, the OFF time of energization to the halogen heater 9 is further extended to lower the surface temperature of the fixing roller 8a.

When the condition of Tdbr ≦ 48 (° C.) continues for 5 minutes, the control device 31 sets the target temperature (Tfrmtgt) of the surface temperature (Trfm) of the fixing roller 8a to 170 (° C.), The surface temperature of the fixing roller 8a is lowered by making the power supply interval to the heater 9 longer, that is, making the power supply OFF time to the halogen heater 9 longer.

As described above, when the temperature of the regulating blade 24, that is, the temperature of the developing device 3 is 40 ° C. or less, the fixing device 8
Is controlled so that the surface temperature of the fixing roller 8a becomes the standard temperature of 200 ° C., and the energization to the halogen heater 9 is controlled so that the surface temperature of the fixing roller 8a decreases as the temperature of the regulating blade 24 increases. Therefore, as the temperature of the fixing roller 8a of the fixing device 8, which is the largest heat source of the image forming apparatus, is lowered, the temperature of the regulating blade 24 of the developing device 3 is reduced as shown in FIG. a)
It will be lower than the case.

The first control mode (Tfrmtgt)
0i) is the case where the standard temperature for the surface temperature of the fixing roller 8a is 200 ° C., but the standard temperature for the surface temperature of the fixing roller 8a is set to 5 ° C. in the first control mode.
The second to fifth control modes (Tfrmtgt) shown in FIG.
1i to 5i), the target temperature (Tfrmtgt) of the surface temperature (Trfm) of the fixing roller 8a is set to 5 ° C.
In the first control mode (Tfrmtgt0).
The energization to the halogen heater 9 is controlled as in the case of i).

Further, the first to fifth control modes (T
If the temperature (Tdbr) of the regulating blade 24 does not fall below 48 ° C. even in the control by frmtgt0i to 5i),
Under the control of the control device 31, the image forming operation is stopped or a warning message is displayed on a display unit (not shown) to notify the user.

As described above, if only the surface temperature of the fixing roller 8a of the fixing device 8 is reduced simply by controlling the energization of the halogen heater 9, the fixing ability may be reduced depending on the type of the transfer material. Therefore, in order to compensate for this, the contact force between the fixing roller 8a and the pressure roller 8b is increased. That is, as shown in FIG.
Pressing springs 65 and 66 as pressing means are connected to both sides of the rotating shaft 63 and the rotating shaft 64 of the pressing roller 8b, respectively, so that the contact force between the fixing roller 8a and the pressing roller 8b ( Frc) is adjusted as shown in FIG. 9 below by changing the length of the pressure springs 65 and 66.

That is, together with the above-described energization control of the halogen heater 9 shown in FIG. 7, as shown in FIG. 9, the distance between the fixing roller 8a and the pressure roller 8b depends on the surface temperature (Trfm) of the fixing roller 8a. The contact force (Frc) is changed. That is, when the surface temperature (Trfm) of the fixing roller 8a is low, the contact force (Frc) between the fixing roller 8a and the pressure roller 8b is increased, and as the surface temperature (Trfm) of the fixing roller 8a increases, the fixing roller 8a increases. The contact force (Frc) between the pressure roller 8b and the pressure roller 8b is reduced.

The contact force between the fixing roller 8a and the pressing roller 8b is adjusted by shortening the length of the pressing springs 65 and 66, so that the contact force between the fixing roller 8a and the pressing roller 8b increases. When the lengths of the pressure springs 65 and 66 are increased, the contact force between the fixing roller 8a and the pressure roller 8b decreases. Adjustment of the length of the pressure springs 65 and 66 can be performed by driving a spring length adjustment mechanism (not shown) under the control of the control device 31.

In the image forming apparatus of the present embodiment,
A4 size standard image ratio (6
7) and FIG. 8 when the image of (%) was output 1 million pages, the evaluation results shown in FIG. 10 and FIG. 21D were obtained. As is clear from the evaluation results, the decrease in the image reflection density is small,
The incidence of fogging was also small.

As described above, in this embodiment, even when the temperature of the developing device 3 rises due to heat generation of the halogen heater 9 of the fixing device 8 during image formation, the regulating blade 22
The power supply to the halogen heater 9 is controlled so as to lower the surface temperature of the fixing roller 8a in accordance with the temperature rise of the developing device 3.
Is lowered, and the contact force between the fixing roller 8a and the pressure roller 8b of the fixing device 8 is adjusted to prevent the image quality from deteriorating due to the rise in the temperature of the developing device 3, so that a high-quality image can be obtained. It can output for a long time.

In the above-described embodiment, when the temperature of the developing device 3 rises, the halogen heater 9 is energized so as to lower the surface temperature of the fixing roller 8a in accordance with the rise in the temperature of the regulating blade 22. Control, and furthermore, the fixing device 8
The contact force between the fixing roller 8a and the pressure roller 8b of the fixing device 8 is adjusted. However, the contact force between the fixing roller 8a and the pressure roller 8b of the fixing device 8 is constant, A configuration for controlling the energization of the halogen heater 9 is also possible.

<Embodiment 2> In Embodiment 1, the resin coating layer 22b is formed on the surface of the base 22a of the developing sleeve 22 of the developing device 3. However, in the present embodiment, it is shown in FIG. As described above, the base 22 of the developing sleeve 22
This is a configuration in which a metal plating layer 22e is formed on the surface a. Other configurations and operations are the same as those of the image forming apparatus of the first embodiment, and the description thereof is omitted in the present embodiment, and the metal plating layer 2 formed on the surface of the base 22 a of the developing sleeve 22 is omitted.
Only 2e will be described.

There are various plating treatments for hardening the surface of the base 22a of the developing sleeve 22.
In the present embodiment, electroless plating is used instead of electroplating. Examples of electroless plating of non-magnetic metal include electroless Ni-P plating, electroless Ni-B plating, and electroless Cr.
Plating is preferred.

As described in the first embodiment, the developing sleeve 20 is nonmagnetic because magnetic toner is used. However, the metal plating applied to the surface of the developing sleeve 20 has a thin plating layer of several μm. Therefore, it can be used even if it has some magnetism. Nevertheless, non-magnetic properties are preferred.

Although nickel (Ni) is a ferromagnetic substance by itself, in the electroless Ni-P plating and Ni-B plating layers,
Nickel becomes amorphous and becomes non-magnetic when combined with phosphorus (P) or boron (B). The phosphorus content in the Ni-P plating film required for such demagnetization is 8 to 10 wt%, and the boron content in the Ni-B plating film is 5 to 7 wt%.

The plating is performed on the base 22a of the developing sleeve 22.
The coating may be applied uniformly on the entire surface, or may be made into a mesh having an arbitrary hole shape. In this case, a mesh-shaped plating can be obtained by plating after performing a mesh-shaped masking process. In order to increase the adhesion between the plating film and the surface of the substrate 22a of the developing sleeve 22, a zincate treatment for forming a zinc alloy film on the surface of the substrate 22a may be performed before the plating.

As described above, electroless plating is used instead of electroplating because the deposited plating metal is deposited on the roughened uneven surface of the base 22a of the developing sleeve 22 without being affected by the unevenness. The reason for this is that a plating film having a uniform thickness can be obtained, and the surface roughness obtained by roughening can be maintained with almost no change. On the other hand, in electroplating, the developing sleeve 22
It is difficult to deposit the plating metal on the concave portion of the roughened surface of the base 22a, and only the convex portion adheres preferentially to the convex portion and is thickly plated, so that a plating film having a uniform thickness cannot be obtained,
The surface roughness changes.

In the image forming apparatus of the present embodiment in which the metal plating layer 22e is formed on the surface of the base 22a of the developing sleeve 22, the halogen heater of the fixing device 8 at the time of image formation is similar to the first embodiment. Even if the temperature of the regulating blade 24 of the developing device 3 rises due to heat generation of the developing device 9, the energization to the halogen heater 9 is controlled so as to lower the surface temperature of the fixing roller 8 a in accordance with the rise in the temperature of the regulating blade 24. By lowering the temperature of the device 3 and adjusting the contact force between the fixing roller 8a and the pressure roller 8b of the fixing device 8, it is possible to prevent the image quality from deteriorating due to the rise in the temperature of the developing device 3, and to obtain a high-quality image. Can be output over a long period of time.

Then, using the image forming apparatus of the present embodiment in which the metal plating layer 22e is formed on the surface of the base 22a of the developing sleeve 22, the A4 size standard is used in a high-temperature and high-humidity environment in the same manner as in the first embodiment. When an image having an image ratio (6%) of 1,000,000 pages was output, the above-described control of FIGS. 7 and 8 was performed simultaneously, and as a result, an evaluation result as shown in FIG. 10 was obtained. As is clear from this evaluation result,
The decrease in image reflection density was small, and the occurrence rate of fog was also small.

As described above, the base 22 of the developing sleeve 22 is
Also in the image forming apparatus of the present embodiment in which the metal plating layer 22e is formed on the surface a, the temperature of the developing device 3 rises due to heat generation of the halogen heater 9 of the fixing device 8 during image formation, as in the first embodiment. Developing device 3
The temperature rise of the image is suppressed to prevent the image quality from deteriorating, and a high-quality image can be output for a long period of time.

<Third Embodiment> In the first embodiment, the temperature sensor 30 is arranged on the regulating blade 24 of the developing device 3 to measure the temperature of the developing device 3. However, in the third embodiment, As shown in FIG. 12, a temperature sensor 3 is attached to a developing container 21 located below a developing sleeve 22 of the developing device 3.
0 is arranged. Also in this case, the highest temperature is on the far side in the vertical direction with respect to the plane of FIG.
A temperature sensor 30 is arranged on the far side in the longitudinal direction of the developing container 21. Other configurations and operations are the same as those of the image forming apparatus of the first embodiment, and a description thereof will be omitted in the present embodiment.

In the image forming apparatus according to the present embodiment in which the temperature sensor 30 is disposed in the developing container 21 located below the developing sleeve 22, similarly to the first embodiment, the halogen of the fixing device 8 at the time of image formation is used. Even when the temperature of the developing container 21 of the developing device 3 rises due to heat generation of the heater 9 or the like, the power supply to the halogen heater 9 is controlled so as to lower the surface temperature of the fixing roller 8a in accordance with the temperature rise of the developing container 21. By lowering the temperature of the developing device 3 and adjusting the contact force between the fixing roller 8a and the pressing roller 8b of the fixing device 8, it is possible to prevent a decrease in image quality due to a rise in the temperature of the developing device 3 and to achieve high quality. Images can be output over a long period of time.

Then, using the image forming apparatus of the present embodiment in which the temperature sensor 30 is disposed in the developing container 21 located below the developing sleeve 22, in the same manner as in the first embodiment, A4 When an image having a standard image ratio of the size (6%) was output by one million pages, the above-described control of FIGS. 7 and 8 was simultaneously performed, and as a result, an evaluation result as shown in FIG. 10 was obtained. As is clear from the evaluation results, the image reflection density did not decrease much, and the occurrence rate of fog was also small.

As described above, in the image forming apparatus of the present embodiment in which the temperature sensor 30 is disposed in the developing container 21 located below the developing sleeve 22, similarly to the first embodiment, the fixing device 8 is formed at the time of image formation. Even if the temperature of the developing device 3 rises due to the heat generated by the halogen heater 9 or the like, the rise in the temperature of the developing device 3 is suppressed to prevent a decrease in image quality, and a high-quality image can be output for a long period of time. .

<Fourth Embodiment> In the first embodiment, the rotation speed of the developing sleeve 22 of the developing device 3 is constant, but in the present embodiment, the rotation speed (Vdahm) of the developing sleeve 22 is constant. Instead, the rotation speed of the developing sleeve 22 is controlled according to the temperature of the developing device 3. That is, in the present embodiment, the heat generated by the rotation of the developing sleeve 22 is taken into consideration. Other configurations and operations are the same as those of the image forming apparatus according to the first embodiment.

In the present embodiment, as shown in FIG.
The rotation speed (Vdahm) of the developing sleeve 22 is controlled in four stages according to the temperature (Tdbr) of the regulating blade 24 of the developing device 3. In the present embodiment, FIG.
As shown in the figure, the output of the temperature sensor 37 disposed on the regulating blade 24 is transmitted to the control device 31,
Outputs a control signal to a sleeve drive motor 67 that rotationally drives the developing sleeve 22 to control the rotational speed of the developing sleeve 22 in four stages.

That is, when the rotation speed of the developing sleeve 22 during the normal image formation is 787.5 mm / sec, the temperature (Tdbr) of the regulating blade 24 becomes Tdbr <
38 (° C.), the rotation speed (V
dahm) is controlled to 819 mm / sec. Also, 38
(° C.) ≦ Tdbr <40 (° C.), the developing sleeve 2
0 rotation speed (Vdahm) to the normal 787.5 mm / sec
Control to c. Also, 40 (° C.) ≦ Tdbr <45 (° C.)
, The rotation speed (Vdahm) of the developing sleeve 22 is set to 7
Control is performed at 24.5 mm / sec. Also, 45 (° C.) ≦
, The rotational speed (Vdahm) of the developing sleeve 22 is set to 6
Control is performed at 75 mm / sec.

Incidentally, the developing sleeve 2 is controlled by the control device 31.
The switching of the rotation speed 2 is, of course, not performed during the developing process in order to avoid an image change on the same transfer material, but one job (one image output command, Output, the size of the transfer material, the type of the original, the position of the staples, etc.). The fluctuation of the formed image is also avoided.

In the image forming apparatus according to the present embodiment in which the rotation speed of the developing sleeve 22 is changed according to the temperature of the regulating blade 24, the halogen heater of the fixing device 8 during image formation is used as in the first embodiment. Even when the temperature of the developing device 3 rises due to the heat generation of the developing device 9, the power supply to the halogen heater 9 is controlled so as to lower the surface temperature of the fixing roller 8 a in accordance with the temperature rise of the regulating blade 24, and the temperature of the developing device 3 is reduced. At the same time, the contact force between the fixing roller 8a and the pressure roller 8b of the fixing device 8 is adjusted, and the rotation speed of the developing sleeve 22 is changed in accordance with the temperature of the regulating blade 24. A high-quality image can be output for a long period of time by preventing a decrease in image quality due to the rise.

Using the image forming apparatus of the present embodiment having the above-described configuration, an image of A4 size standard image ratio (6%) in a high-temperature and high-humidity environment is used for one million pages in the same manner as in the first embodiment. At the time of output, as a result of performing the above-described control of FIG. 7 and FIG. 8 simultaneously, an evaluation result as shown in FIG. 10 was obtained. As is clear from the evaluation results, the image reflection density did not decrease much, and the occurrence rate of fog was also small.

As described above, in the image forming apparatus of the present embodiment in which the rotation speed of the developing sleeve 22 is controlled in accordance with the temperature of the developing apparatus 3, similarly to the first embodiment, the fixing device 8 is used for forming the image. Even when the temperature of the developing device 3 rises due to the heat generated by the halogen heater 9 or the like, it is possible to suppress a rise in the temperature of the developing device 3 and prevent a decrease in image quality, thereby outputting a high-quality image for a long period of time.

Further, in the image forming apparatus of each of the above-described embodiments, the developing device having the configuration in which the fixed magnet roller is disposed in the developing sleeve is provided.
Not only the developing sleeve but also the magnet roller contained therein rotates together, one having two or more developing sleeves, one having a cylindrical developer layer forming member, and a two-component developer composed of toner and carrier. The developer may be used, a developer using only a non-magnetic toner, a developer sleeve in contact with the photosensitive drum, or a developer sleeve having a belt shape may be used.

In the image forming apparatus of each of the embodiments described above, the regulating blade as the developer layer thickness regulating member is arranged so as to be in non-contact with the developing sleeve.
In addition, for example, a regulating blade made of an elastic material that comes into contact with the surface of the developing sleeve shown in FIG. 16 can also be used.

Further, in the image forming apparatus of each of the above-described embodiments, a fixing device for performing thermal fixing by nipping and conveying a transfer material carrying an unfixed toner image in a fixing nip between a pair of fixing rollers and a pressure roller. However, in addition to this, for example, a fixing device that sandwiches and conveys a transfer material by a fixing nip between a film-shaped fixing member having a built-in heater and a pressure roller and that is thermally fixed as illustrated in FIG. 19 is used. Can also.

[0126]

As described above, according to the first aspect of the present invention, the power supply to the heating element of the fixing unit is controlled based on the temperature information near the developing unit measured by the temperature measuring unit during image formation. By adjusting the heating temperature of the heating element
It is possible to suppress a rise in the temperature of the developing unit, prevent a decrease in image quality due to a rise in the temperature of the developing unit, and output a high-quality image for a long period of time.

According to the second aspect of the present invention, the power supply to the heating unit of the fixing unit is controlled based on the temperature information near the developing unit measured by the temperature measuring unit at the time of image formation to generate heat of the heating unit. By adjusting the temperature and controlling the pressing force of the pressing unit to adjust the contact force between the fixing member and the pressing member, it is possible to suppress a rise in the temperature of the developing unit and increase the temperature of the developing unit. Thus, it is possible to output a high-quality image for a long period of time by preventing the image quality from deteriorating.

[Brief description of the drawings]

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

FIG. 2 is a schematic sectional view showing a developing device of the image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a schematic sectional view showing a developer supply container.

FIG. 4 is a schematic sectional view showing a part of a developing sleeve of the developing device according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a relationship between the number of image output pages and temperature rises before, at the center, and at the back of a regulating blade.

FIG. 6 is a schematic sectional view showing a fixing device according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating surface temperature control of the fixing roller with respect to the temperature of the regulating blade according to the first embodiment of the present invention.

FIG. 8 is a perspective view showing a fixing roller and a pressure roller of the fixing device according to the first embodiment of the present invention.

FIG. 9 is a diagram illustrating control of a contact force between a fixing roller and a pressure roller with respect to a surface temperature of the fixing roller according to the first embodiment of the present invention.

FIG. 10 is a diagram showing evaluation results in each embodiment of the present invention.

FIG. 11 is a schematic sectional view showing a part of a developing sleeve of a developing device according to a second embodiment of the present invention.

FIG. 12 is a schematic sectional view showing a developing device of the image forming apparatus according to Embodiment 3 of the present invention.

FIG. 13 is a diagram illustrating control of the rotation speed of the developing sleeve with respect to the temperature of the regulating blade according to the fourth embodiment of the present invention.

FIG. 14 is a block diagram illustrating a rotation speed control system of a developing sleeve according to a fourth embodiment of the present invention.

FIG. 15 is a schematic configuration diagram showing an image forming apparatus in a conventional example.

FIG. 16 is a schematic cross-sectional view illustrating an example of a developing device of an image forming apparatus in a conventional example.

FIG. 17 is a schematic cross-sectional view illustrating an example of a developing device of an image forming apparatus in a conventional example.

FIG. 18 is a schematic cross-sectional view illustrating an example of a fixing device of an image forming apparatus in a conventional example.

FIG. 19 is a schematic sectional view showing an example of a fixing device of an image forming apparatus according to a conventional example.

FIG. 20 is a diagram illustrating a relationship between the number of image output pages and a rise in the temperature of a regulating blade.

FIG. 21 is a diagram illustrating a relationship between the number of image output pages and the image reflection density.

FIG. 22 is a diagram illustrating the relationship between the number of image output pages and the rise in the temperature of the regulating blade in the presence or absence of an intermediate tray.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum (image carrier) 2 primary charger 3 developing device (developing means) 4 transfer charger (transfer means) 5 separation charger 6 cleaning device 7 exposing device 8 fixing device (fixing device) 8a fixing roller (fixing) 8b Pressure roller (pressure member) 9 Halogen heater (heating body) 20 Drum heater 21 Developing container 22 Developing sleeve (Developer carrier) 23 Magnet roller 24 Regulator blade 29 Developing power supply 30 Temperature sensor (Temperature measuring means) 31 control device (control means) 65, 66 pressurizing spring (pressurizing means) 67 sleeve drive motor

Claims (4)

[Claims] A developing unit that attaches a developer to the electrostatic latent image formed on the image carrier to visualize the image as a developer image; a transfer unit that transfers the developer image to a transfer material; A pair of fixing members and a pressing member; and a heating member provided at least inside one of the fixing member and the pressing member. Fixing means for fixing the developer image to the transfer material by heating and pressing, and heating and fixing the developer image on at least one surface of the transfer material, and then discharging the image. A temperature measuring unit for measuring a temperature in the vicinity of the developing unit; and controlling the energization of the heating unit of the fixing unit based on temperature information in the vicinity of the developing unit measured by the temperature measuring unit during image formation. Adjust the heating temperature of the heating element A control means for the image forming apparatus characterized by. 2. The developing device according to claim 1, wherein the developing unit carries the developer on a surface thereof and applies a developing voltage to apply a developer to an electrostatic latent image on the image carrier at a developing position. 2. The image according to claim 1, further comprising a developer carrier, wherein the control unit simultaneously controls a rotation speed of the developer carrier based on temperature information input from the temperature measuring unit. 3. Forming equipment. 3. A developing means for adhering a developer to an electrostatic latent image formed on an image carrier to visualize it as a developer image, a transfer means for transferring the developer image to a transfer material, A pair of fixing members and a pressing member, a heating member provided at least inside one of the fixing member and the pressing member, and a pressure for pressing the fixing member and the pressing member to make contact with each other. Fixing means for fixing the developer image by heating and pressing the transfer material between the fixing member and the pressing member by pressurization by the pressing means and heat generated by the heating element. An image forming apparatus that heats and pressurizes and fixes a developer image on at least one surface of the transfer material, and discharges the image after fixing. A temperature measuring unit that measures a temperature near the developing unit; Near the developing means measured by the measuring means On the basis of the temperature information, the power supply to the heating element of the fixing unit is controlled to adjust the heat generation temperature of the heating element, and the pressing force of the pressing unit is controlled to control the fixing member and the pressing member. Control means for adjusting a contact force between the image forming apparatuses. 4. A rotatably supported developing means for supporting the developer on a surface thereof and applying the developer to an electrostatic latent image on the image carrier at a developing position by applying a developing voltage. 4. The image forming apparatus according to claim 3, further comprising a developer carrier, wherein the control unit simultaneously controls the rotation speed of the developer carrier based on temperature information input from the temperature measuring unit. 5. apparatus.