JP3288905B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus having a double-sided image forming function, and more particularly to an image forming apparatus in which deterioration of rubber of a fixing means is reduced.

[0002]

2. Description of the Related Art In a fixing device of an electrophotographic image forming apparatus such as a copying machine or a laser beam printer, a recording material on which a toner image is transferred is sandwiched between a pair of rollers of the fixing device to heat and press the toner. Thus, the toner image is fixed on the recording material to form a permanent image.

The outer layer of the roller used in the fixing device is generally formed by coating a material having good releasability, heat resistance and abrasion resistance, such as fluororesin and silicon rubber. In particular, in the case of a full-color copying machine that emphasizes image quality,
There is a tendency to use a fixing roller in which the surface of the roller is covered with silicone rubber. Further, since this silicone rubber alone has low strength and has a problem in use as a roller, for example, reinforcing silica, titanium oxide, alumina powder and the like are mixed and reinforced to improve physical strength. .

[0004]

In recent years, with the widespread use of color copiers, the image forming speed has been increased and the set fixing temperature has been increased. On the other hand, with the demand for lowering running costs, it is desired to extend the life of the fixing / pressing roller.

However, increasing the image forming speed, setting the fixing temperature to a higher temperature, and the like also cause deterioration of the roller, and it has been difficult to satisfy the demand for extending the life of the roller. Specifically, when the set temperature is set to a relatively high temperature (170 ° C. or higher) and the device is durable for a long time, the fixing / pressing roller using the above-described silicon rubber for the surface layer is deteriorated by heat or toner, Strength decreases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in view of the above circumstances.
It is an object to provide an image forming apparatus having image stability.

[0007]

The above objects can be achieved by the present invention described below.

An image having a fixing means for fixing an image formed on a recording material by sandwiching and conveying the recording material between a fixing member and a pressing member, and an oil applying means for supplying an application oil to the fixing means. In the image forming apparatus, the coating oil contains a metal ionic compound of at least one metal selected from the group consisting of transition metals, aluminum and gallium.

Fixing means for fixing the image formed on the recording material by nipping and conveying the recording material between the fixing member and the pressing member; and a cleaning member for cleaning the fixing member and / or the pressing member. Wherein the cleaning member includes a metal ionic compound of at least one metal selected from the group consisting of transition metals, aluminum and gallium.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a coating oil or a cleaning member contains a specific metal ionic compound (such as a metal salt). On the other hand, silicone rubber or the like used for fixing means such as a fixing roller has a tendency that siloxane bonds are cut by a substance having strong ionicity, rubber strength is reduced, and the rubber is easily damaged. Here, the specific metal ionic compound in the present invention has an action of attracting and capturing the ionic substance by electrostatic force and preventing reaction with the silicone rubber.

Hereinafter, a preferred embodiment of the image forming apparatus of the present invention will be described.

FIG. 1 is a schematic configuration diagram showing one embodiment of the image forming apparatus of the present invention. The apparatus according to the present aspect forms an image on both surfaces of the recording material by conveying the recording material on which the image formation and fixing on the first surface are again performed to the image forming unit and the fixing unit and performing image formation and fixing on the second surface. This is an electrophotographic color image forming apparatus having a double-sided image forming function.

In FIG. 1, reference numeral 1 denotes an outer casing of the apparatus main body, and A denotes a document scanning / reading section disposed on the upper part of the outer casing of the apparatus main body. An original O is set on the original platen glass 2 with its image surface facing down according to a predetermined device reference, and a document holding plate 3 is placed over the original O to start reading, whereby the moving optical system below the original platen glass is started. 4 moves from one side to the other side along the lower surface of the platen glass to illuminate and scan the downward image surface of the set document on the platen glass 3, and the original surface reflected light of the scanning light is read by a photoelectric reading unit. 5 and color-separated by a color-separation filter. Each color-separated component image of the original image is photoelectrically read as a color image signal (a time-series electric digital pixel signal) and stored in a memory circuit.

Reference numeral 6 denotes an electrophotographic photosensitive drum as an image carrier of the image forming unit. The photosensitive drum 6 has a diameter of, for example, 180 mm, and is driven to rotate clockwise as indicated by an arrow at a predetermined process speed (peripheral speed). Reference numeral 7 denotes a charger for uniformly charging the photosensitive drum 6 to a predetermined polarity and potential, and reference numeral 8 denotes an image exposing means including a laser output unit, a polygon mirror, a lens system, a mirror, and the like. The charged surface of the photosensitive drum by the charger 7 is scanned and exposed by the laser beam E modulated and output from the image exposing means 8 in accordance with the time-series electric digital pixel signal from the memory circuit, thereby rotating the photosensitive drum. Electrostatic latent images corresponding to the scanning exposure patterns are formed on six surfaces.

A composite developing device 9 includes a cyan developing device 9C containing cyan toner, a magenta toner developing device 9M containing magenta toner, a yellow developing device 9Y containing yellow toner, and a black developing device 9Y containing black toner. And four developing units 9C, 9M, 9Y and 9K selectively act on the rotating photosensitive drum 6 to form an electrostatic latent image on the rotating photosensitive drum 6 surface. The toner is developed.

Reference numeral 11 denotes a transfer drum, which is a composite developing device 9
Next to the photosensitive drum 6, the photosensitive drum 6
The photosensitive drum 6 is driven to rotate in the forward direction at substantially the same peripheral speed as that of the photosensitive drum 6. The transfer drum 11 has a diameter of, for example, 180 mm, and a recording material carrying sheet 11a made of a film-like dielectric material serving as a recording material carrying means is integrally stretched in a cylindrical shape in a peripheral opening area. Further, an adsorbing corona charger 11b, which is an adsorbing and charging means for adsorbing the recording material to the outer peripheral surface of the transfer drum 11, and an adsorbing (contact) roller 11c as a counter electrode thereof, a transfer drum 11
Transfer corona charger 11d, inner corona charger 11e, outer corona charger 11f, recording material separating charger 11g, recording material separating claw for transferring the toner image on the photosensitive drum 6 side to the recording material adsorbed on the recording medium 11h and so on are provided.

Reference numerals 12, 13, and 14 denote first to third automatic recording material feeding mechanisms, and reference numeral 15 denotes a recording material manual feeding section. The recording material (transfer material) P is fed one by one from any of the selected first to third recording material automatic paper feeding mechanisms 12, 13, and 14, and is a predetermined sheet composed of a guide plate, a conveying roller pair and the like. The sheet is conveyed to the registration roller pair 16 through the path. Alternatively, the recording material is conveyed from the manual paper feed unit 15 to the pair of registration rollers 16.

The recording material is fed to the transfer drum 11 by the registration roller pair 16 at a predetermined timing, is wound around the outer peripheral surface of the transfer drum 11, is electrostatically held, and is integrated with the transfer drum 11. The recording material is rotated and conveyed, and the toner image on the photosensitive drum 6 side is transferred to the outer surface of the recording material by the transfer corona charger 11d. After the transfer of the toner image to the recording material P, the surface of the rotating photosensitive drum 6 is cleaned by a cleaner (cleaning device) 10 after removing residual deposits such as untransferred toner.

In the case of the full-color image forming mode,. Charged to the rotating photoreceptor drum 6 → image exposure E by laser light modulated by a cyan image signal of the aforementioned color separation image signal of the target color image → development by cyan developing device 9C → recording material of the cyan toner image Step of transfer to P → cleaning of the rotating photosensitive drum 6. Charge to the rotating photosensitive drum 6 → image exposure E of laser light modulated by a magenta image signal of the above-mentioned color separation image signal of a target color image → development by magenta developing device 9M → recording material of the magenta toner image Step of transfer to P → cleaning of the rotating photosensitive drum 6. Charged to the rotary photoreceptor drum 6 → Image exposure E by laser light modulated by a yellow image signal of the aforementioned color separation image signal of the target color image → Development by yellow developing device 9Y → Recording material of the yellow toner image Step of transfer to P → cleaning of the rotating photosensitive drum 6. Charged to the rotating photosensitive drum 6 → Image exposure E by laser light modulated by a black image signal of the above-mentioned color separation image signal of the target color image → Development by black developing device 9K → Recording material of the black toner image The rotation of the photosensitive drum 6 and the transfer drum 11 in the four image forming / transfer cycles from the transfer to P → the cleaning process of the rotary photosensitive drum 6 are sequentially executed, so that the image is wound around the rotary transfer drum 11. The four toner images of the cyan toner image, the magenta toner image, the yellow image, and the black toner image are mutually aligned with respect to the outer surface (first surface) of the held same recording material P (registration). ) Is superimposed and transferred, so that a color toner image corresponding to the target color image is synthesized and formed on the recording material P. Is done.

When the transfer of the four color toner images onto the same recording material P held on the rotary transfer drum 11 is completed, the recording material is neutralized by a separation charger 11g.
The transfer drum 11 is separated by a separation claw 11h as a separation unit.
The toner image for four colors is sent to a fixing device (a heat roller fixing device in this example) 18 by a conveying unit 17 and is collectively fixed on the surface of the recording material.

In the single-sided image forming mode, the fixing device 1
The recording material on which a single-sided (first side) image has been formed and fixed has exited 8 is discharged from a paper discharge port 19 to a paper discharge tray 20 outside the apparatus.

In the duplex image forming mode, the fixing device 1
The recording material on which the single-sided image formed and fixed has exited 8 is introduced into the re-conveying sheet path a, is reversed upside down through the path of switchback sheet path b → sheet path c, and
Sent to 1. Then, the sheet is conveyed from the intermediate tray 21 to the registration roller pair 16 and fed again to the transfer drum 11, and is wound around the transfer drum 11 in an inward direction on the first surface side and an outward direction on the second surface side after image formation. Is done.

On the second surface of the recording material, similarly to the image formation on the first surface, four color-separated toner images of the color image for the second surface sequentially formed on the photosensitive drum 6 Are sequentially performed to form a color toner image.

The recording material is separated from the transfer drum 11 and sent to the fixing device 18 again to form the recording material on the second surface.
The toner images for the colors are collectively fixed, and the recording material on which the full-color double-sided image has been formed is discharged from the discharge port 19 to the discharge tray 20.

The recording material on which a single-sided (first side) image has been formed and fixed is once discharged to a paper discharge tray 20, and the recording material is turned upward on the second side and re-introduced into the apparatus from the manual paper feed unit 15 to be removed. Image formation on two surfaces can also be executed.

The order in which the four color-separated toner images are formed is not limited to the order of this embodiment. In the case of copying a monochrome image, only the black developing device 9K operates. A two-sided copy mode for monochrome images and a color image for one side of the recording material
An image forming mode for making the other surface a black and white image can also be selectively executed.

Next, a preferred embodiment of the fixing device, which is a feature of the present invention, will be described with reference to FIG. FIG. 2 is an enlarged schematic view of a main part of the fixing device 18 in FIG. The fixing roller 29 as a fixing member has an HTV (high temperature vulcanization type) silicone rubber layer 32 on a cored bar 31 and an RTV (room temperature vulcanization type) silicone rubber layer 33 on the outside thereof. On the other hand, the pressure roller 30 as a pressure member is formed by providing an HTV silicone rubber on a cored bar 34 and a fluororesin layer 35 on the surface thereof.

The fixing roller 29 is provided with a halogen heater 36 which is a heating means, and the pressure roller 30 is also provided with a heater 37 in a metal core for heating both sides of the recording material. The temperature of the pressure roller is detected by a thermistor 38 in contact with the pressure roller 30, and the halogen heaters 36 and 37 are controlled by the control device 39 based on the detected temperature.
Is controlled, the temperature of the fixing roller 29 and the pressure roller 30
Is controlled. The fixing roller 29 and the pressure roller 30 are pressed by a pressure mechanism (not shown).

T is an unfixed toner image on the recording material P. 50 is a coating device for applying a coating oil as a release agent to the fixing roller 29, and 60 is a cleaning device for the fixing roller 29. 70 is a cleaning device for the pressure roller 60.

Oil coating device 5 for fixing roller 29
0 is applied on the application oil pumping roller 42 and the oil application roller 43 in the oil pan 40. Note that the oil application roller 43 can be moved toward and away from the fixing roller 29.

Cleaning device 60 for fixing roller
The cleaning is performed by pressing the nonwoven fabric web 46 against the fixing roller 29 by the pressing roller 45.

In the present invention, a specific metal ionic compound (metal salt or the like) is contained in the coating oil 41 or the nonwoven fabric web 46 as a cleaning member,
Rubber deterioration of the fixing means (the fixing roller 29, the pressure roller 30, etc.) is reduced. As the metal of the metal ionic compound, one or more metals selected from the group consisting of transition metals, aluminum and gallium are used. As transition metals, Sc (scandium), Ti (titanium), V
(Vanadium), Cr (chromium), Mn (manganese),
Fe (iron), Co (cobalt), Ni (nickel), C
u (copper), Zn (zinc), Zr (zirconium), Mo
(Molybdenum), Pd (palladium), Ag (silver) and the like are desirable. These metals are used alone or in combination of two or more. These are metals that efficiently capture ionic substances in trace amounts and are inexpensive.

Examples of the metal ionic compound include metal organic acid salts such as octylates and naphthenates containing the above-mentioned metal elements; metal organic complexes such as olefins, alkenyls and diketones; alkenylsilanes and diketosilanes Metal silane complex; a metal inorganic salt paired with an inorganic ion such as a halogen ion, a sulfate ion or a nitrate ion; and the like.

As the coating oil, various known oils can be used. For example, dimethyl silicone oil, phenyl silicone oil, fluorosilicone oil, silicon functional silicone oil, carbon functional silicone oil and the like are preferable.

When a metal ionic compound is contained in the coating oil, the amount of the metal ionic compound may be appropriately determined in consideration of the solubility and dispersibility of the metal ionic compound in the oil. Usually, it is desirable to mix about 1 to 1,000 ppm of a metal ionic compound with the oil from the viewpoint of reducing the damage of the roller. When a metal ionic compound or the like that is insoluble in oil is used, an oil stirring device (not shown) may be provided in the oil pan 41 so that the metal ionic compound is dispersed in the oil.

In the prior art, a method is employed in which dimethyl silicone oil is previously contained in the fixing roller 29 and the pressure roller 30 before image formation to obtain an initial toner releasability. Similarly, in the present invention, it is also desirable that the metal ionic compound-containing oil is contained in the fixing roller 29 and the pressure roller 30 in advance before image formation.
For example, if the roller is immersed in oil at about 100 ° C. for several hours in advance, the oil enters the rubber of the roller and swells.
Here, when the metal ionic compound is dissolved or dispersed in the oil to make it saturated, the metal ionic compound enters the rubber together with the oil. In this way, if the metal ionic compound is held in the rubber from the beginning, by combining this with the oil application containing the metal ionic compound,
Further, the life of the roller can be extended.

In the present invention, it is general to prepare an oil solution of a metal ionic compound in advance and supply the solution to an oil pan. Can be placed in the oil pan 40 so that the metal ionic compound dissolves in the applied oil in the oil pan 40. In this case, the metal ionic compound placed in the oil pan 40 dissolves in a coating oil (such as dimethyl silicone oil containing no impurities), and is applied to the fixing / pressure roller by the oil application device 50. Further, since the oil is heated to a high temperature by the heat from the fixing device, even if the oil has a low solubility in the oil, it can be well dissolved in the oil. Furthermore, even if a metal salt that is insoluble in oil is put into the oil pan 40 from the beginning and the oil is constantly stirred by a stirrer (not shown), the metal salt precipitates at the bottom of the oil pan 40. The toner is sufficiently dispersed without being transferred to the fixing roller 29 and the pressure roller 30. According to such a method, it is not always necessary to change the supplied application oil from the conventional one.

When the nonwoven fabric web 46 (cleaning member) contains a metal ionic compound, for example, the cleaning member is immersed in a coating oil or solvent containing desirably about 1 to 1,000 ppm of the metal ionic compound. Use things. When the metal ionic compound is held in the nonwoven fabric web 46, the metal ionic compound is dispersed in the applied oil on the roller, so that the metal ionic compound is always rich on the roller. Also, the nonwoven web 46
Has a feed mechanism, so that a new surface always comes into contact with the fixing roller, and a new metal ionic compound is supplied to the surface of the fixing / pressure roller.

As the coating oil containing the metal ionic compound, the same oil as described above can be suitably used. On the other hand, when a solvent containing a metal ionic compound is used, the solvent is volatilized when the impregnated web is left in the air, and the metal ionic compound adheres to the web. This allows for more even distribution of the metal ionic compound on the web than sprinkling by hand. The adhesive force of the metal ionic compound on the web is very weak, and the pressing roller 4
When pressed by 5, the metal ionic compound separates from the web and the fixing roller 29 is always in a state rich in the metal ionic compound.

Examples of the solvent include saturated hydrocarbons such as hexane and heptane; aromatic hydrocarbons such as toluene and ethylbenzene; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate and butyl acetate; alcohols such as ethanol and methanol. An organic solvent selected from organic compounds that are liquid at room temperature is used alone or as a mixed solvent of two or more kinds. Also in this case, the concentration of the metal ionic compound is desirably about 1 to 1,000 ppm.

In the above embodiment, the embodiment in which the nonwoven fabric web contains the coating oil or the solvent containing the metal ionic compound has been described. In addition, the embodiment in which the web pressing roller 45 contains the metal ionic compound. Is also possible. That is, conventionally, the material used for the pressing roller 45 is a soft material having heat resistance such as foamed silicone rubber. These materials have a structure in which there is a large gap between molecular chains and oil or the like easily penetrates. Therefore, when the pressing roller is impregnated with the oil or the solvent mixed with the metal ionic compound, a large amount of the metal ionic compound is held in the pressing roller 45. When the web 46 is pressed against the fixing roller 29 by the pressing roller 45,
The pressing roller 45 is heated by oil and heat on the fixing roller 29.
The metal ion compound contained therein starts to mix into the oil, and the metal ion compound becomes rich on the surfaces of the fixing roller 29 and the pressure roller 30. Furthermore, by combining this with the web 46 containing a metal ionic compound, rubber deterioration due to toner is further reduced, and the durability of the roller is increased.

In the above embodiment, the fixing roller 29 and the pressure roller 30 have been particularly exemplified as the fixing means for reducing the deterioration by the metal ionic compound.
Other fixing means such as an oil removing blade 7
0, the oil application rollers 42 and 43, the application blade 44 and the like are also reduced in deterioration by the metal ionic compound, and the life of each member is extended.

[0043]

The present invention will be described in more detail with reference to the following examples.

Example 1 and Comparative Example 1 In the image forming apparatus shown in FIGS. 1 and 2, 300 ppm of a metal ionic compound, iron (III) chloride, was added to dimethyl silicone oil (KF96 300CS manufactured by Shin-Etsu Chemical Co., Ltd.). This was mixed to form a coating oil 41.

The fixing roller 29 is made of an aluminum core 3.
HTV silicone rubber layer 32 on top of RTV 1 and RTV on the outside
It had a silicone rubber layer 33, and the total thickness of the layer 32 and the layer 33 was 3 mm and the diameter was 40 mm. The pressure roller 30 has an HTV silicone rubber layer having a thickness of 1 mm on an aluminum core 34 and a fluororesin layer 35 on the surface thereof.
Was provided so as to have a diameter of 40 mm. Both the temperature of the fixing roller 29 and the temperature of the pressure roller 30 are about 170 ° C.
It was controlled to keep it. Fixing roller 29 and pressure roller 3
0 was pressurized at a total pressure of about 40 kg.

Using this apparatus, an oil application amount of 0.02 g
At / A4, 10,000 sheets were durable, and the surface roughness of the fixing roller was measured. For comparison, 10,000 sheets were similarly subjected to durability using a coating oil containing no metal ionic compound. The oil application amount is a value obtained by measuring the difference in weight by passing 50 blank papers each with and without oil application.

As a result, data on the roller surface roughness depending on the number of durable sheets as shown in FIG. 3 was obtained. As is clear from FIG. 3, by mixing iron (III) chloride into the applied oil,
Rubber deterioration of the fixing roller 29 is reduced, and scratches (Rz) are reduced.

[Example 2, Comparative Examples 2 and 3] Coating oil (dimethyl silicone oil: KF963 manufactured by Shin-Etsu Chemical Co., Ltd.)
00CS), iron (III) chloride, a metal ionic compound
, And the nonwoven web was immersed in the mixture. Except that this web was used instead of the coating oil containing the metal ionic compound, 20,000 sheets were durable in the same manner as in Example 1, and the surface roughness of the fixing roller was measured. For comparison, a nonwoven fabric web containing no oil (Comparative Example 2) and a nonwoven fabric web containing an applied oil containing no metal ionic compound (Comparative Example 3) were used to similarly endure 20,000 sheets. Done.

As a result, as shown in FIG. 4, data on the roller surface roughness depending on the number of durable sheets was obtained. As is clear from FIG. 4, by mixing iron (III) chloride in the applied oil,
Rubber deterioration of the fixing roller 29 is reduced, and scratches (Rz) are reduced.

Example 3 Example 1 was repeated except that 600 ppm of iron (III) sulfate was used instead of iron (III) chloride.
In the same manner as described above, 10,000 sheets were durable. As a result, almost the same good results were obtained as shown in FIG. That is, by mixing iron (III) sulfate into the application oil, the rubber deterioration of the fixing roller 29 is reduced, and the flaw (Rz) is reduced. Other than this, good results are obtained with, for example, iron (II) chloride, aluminum chloride, aluminum sulfate, potassium potassium chloride and the like.

[0051]

As described above, according to the present invention, the deterioration of the rubber after the durability of the fixing means can be reduced, so that the durability of the fixing means can be obtained and the image stability can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating one embodiment of an image forming apparatus of the present invention.

FIG. 2 is an enlarged schematic view of a main part of the fixing device 18 in FIG.

FIG. 3 is a graph showing the relationship between the surface roughness of a fixing roller and the number of endurable sheets in Example 1.

FIG. 4 is a graph showing the relationship between the surface roughness of a fixing roller and the number of endurable sheets in Example 2.

FIG. 5 is a graph showing the relationship between the surface roughness of a fixing roller and the number of endurable sheets in Example 3.

[Explanation of symbols]

 P Recording material t Unfixed toner image 18 Fixing device 29 Fixing member (fixing roller) 30 Pressing member (pressing roller) 40 Oil pan 41 Applying oil 42 Oil pumping roller 43 Oil applying roller 45 Pressing roller 46 Nonwoven fabric web 50 Oil applying Apparatus 60 Fixing roller cleaning device 70 Pressure roller cleaning device

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideo Kawamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Kazuo Kishino 3-30-2 Shimomaruko, Ota-ku, Tokyo (56) References JP-A-60-260978 (JP, A) JP-A 64-15781 (JP, A) JP-A 64-15782 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) G03G 15/20 104 G03G 15/20 105

Claims (7)

(57) [Claims] A fixing unit that fixes an image formed on the recording material by nipping and conveying the recording material between a fixing member and a pressing member; and an oil application unit that supplies an application oil to the fixing unit. The image forming apparatus according to claim 1, wherein the coating oil contains a metal ionic compound of at least one metal selected from the group consisting of transition metals, aluminum, and gallium. 2. The image forming apparatus according to claim 1, wherein the coating oil contains the metal ionic compound in an amount of 1 to 1,000 ppm. 3. The image forming apparatus according to claim 1, wherein the fixing member and / or the pressing member include the metal ionic compound. 4. The coating oil according to claim 1, wherein said metal ionic compound dissolves in said coating oil in a coating oil pan.
The image forming apparatus as described in the above. 5. A fixing means for fixing an image formed on a recording material by nipping and conveying the recording material between a fixing member and a pressure member, and cleaning for cleaning the fixing member and / or the pressure member. An image forming apparatus comprising: a cleaning member; and a metal ionic compound of at least one metal selected from the group consisting of transition metals, aluminum, and gallium. 6. The image forming apparatus according to claim 5, wherein said cleaning member comprises a nonwoven fabric and a member for pressing said nonwoven fabric. 7. The image forming apparatus according to claim 6, wherein the cleaning member includes an oil containing the metal ionic compound or a solvent containing the metal ionic compound.