JP2004245941A - Image forming device - Google Patents

Abstract

Provided is an image forming apparatus that can always use an optimal transfer bias even when the temperature inside the apparatus changes or is used for a long time, and that can form a good image without causing transfer failure.
In an image forming apparatus for transferring a toner image on an image carrier to a transfer material or an intermediate transfer member by a transfer roller to which a transfer bias is applied, an output value of the transfer bias is detected. And a heating unit for heating the transfer roller 7, and controls the heating unit based on a detection result by the detection unit.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine and a laser beam printer.
[0002]
[Prior art]
The following description relates to an image forming apparatus including a photosensitive drum that forms an electrostatic latent image and then develops and carries a charged toner image, and a transfer roller (transfer member) that is arranged in contact with the photosensitive drum. And
[0003]
The above-described transfer roller is constituted by a metal core and a conductive elastic layer that surrounds the outer peripheral surface of the metal core in a cylindrical shape. Both ends of the core are pressed toward the photosensitive drum by a predetermined pressure. By applying pressure, the elastic layer is pressed against the surface of the photosensitive drum to form a belt-shaped transfer nip between the elastic layer and the photosensitive drum. When transferring the toner image formed on the surface of the photosensitive drum to a transfer material such as paper, a transfer bias is applied to the transfer roller by a power supply while nipping and transferring the transfer material at the transfer nip. Thus, a predetermined charge is applied to the back surface of the transfer material, and the transfer is performed by charging. Then, the toner image on the transfer material is heated and melted by a fixing device and fixed on the transfer material. Incidentally, the elastic layer of the above-described transfer roller is formed of an elastic material such as rubber or urethane. Further, such a transfer configuration has an advantage that a required transfer bias can be applied with a lower power supply voltage as compared with a conventionally used corotron charger.
[0004]
This transfer roller needs to be set to a uniform electric resistance value without unevenness locally in order to apply uniform charge to the back surface of the transfer material. It is difficult to manufacture a uniform resistance value in a medium resistance region, and a member having a uniform resistance in the medium resistance region is manufactured by mixing an ionic conductive substance such as sodium perchlorate.
[0005]
By the way, it is known that the resistance value of the above-mentioned transfer roller has a temperature characteristic, and the temperature inside the apparatus is increased by the heat of the fixing device during continuous use, and the inside of the apparatus is exhausted when left for a long time. The resistance value of the transfer roller changes with the use condition such as normal temperature, so the transfer bias is adjusted and the transfer current is applied to give the necessary amount of charge to the back surface of the transfer material. .
[0006]
For example, as shown in FIG. 5, the bias applied to the transfer roller to supply the necessary transfer current requires 4.0 kV when the internal temperature is 25 ° C. and 1.5 kV when the internal temperature is 45 ° C. This is because the resistance value of the transfer roller is high when the internal temperature is low, and the resistance value is low when the internal temperature is high.
[0007]
[Problems to be solved by the invention]
However, when the resistance value of the transfer roller becomes excessively high, the amount of discharge current in the direction of the photosensitive drum 1 flowing through the gap 20 near the transfer nip is smaller than the amount of transfer current in the direction of the photosensitive drum 1 flowing through the transfer nip 19 shown in FIG. As a result, the toner on the photosensitive drum 1 or the transfer material 5 is charged to a polarity inappropriate for transfer, that is, a polarity opposite to the normal polarity of the toner, in the gap 20 near the transfer nip. There is a problem that transfer defects such as irregularities occur.
[0008]
To prevent this, the transfer roller having a low resistance may be used in advance to lower the necessary transfer bias at 25 ° C. in FIG. 5, but as the internal temperature increases, the resistance of the transfer roller 7 further decreases. As shown in FIG. 6, when the transfer material 5 is nipped and conveyed, an excessive current flows to the end of the photosensitive drum 1 with which the transfer roller 7 is in direct contact, and the portion is normally electrostatically charged at the next image formation. There is a problem that a latent image cannot be formed.
[0009]
In addition to the change in the resistance value of the transfer roller 7 due to the temperature characteristics, when the transfer roller 7 is used for a long time in an energized state, the bias applied to the transfer roller to flow the necessary transfer current increases as shown in FIG. There is also a problem that the resistance value of the roller increases and transfer failure occurs.
[0010]
Therefore, the present invention provides an image forming apparatus that can always use an optimum transfer bias even when the temperature inside the apparatus changes or is used for a long time, and can form a good image without causing transfer failure. With the goal.
[0011]
[Means for Solving the Problems]
According to the present invention, there is provided an image carrier for carrying a toner image, a rotatable transfer roller disposed opposite to the image carrier, a power supply for applying a voltage to the transfer roller, and an output of the power supply. And a heating means for heating the transfer roller, and when the transfer material is nipped and conveyed between the image carrier and the transfer roller, the transfer roller supplies the toner with the power supply. In the image forming apparatus for transferring the toner image on the image carrier to the transfer material by applying a bias having a reverse polarity, the heating unit is controlled based on a detection result of the power output detection unit. And
[0012]
According to a second aspect of the present invention, there is provided an image carrier for carrying a toner image, a rotatable transfer roller disposed opposite to the image carrier via a transfer material carrier, and applying a voltage to the transfer roller. Power supply, power supply output detection means for detecting the output of the power supply, and heating means for heating the transfer roller, wherein the transfer material carried and transported by the transfer material carrier and the transfer material carrier The toner image on the image carrier is transferred to the transfer material by applying a bias having a polarity opposite to that of the toner with the power supply to the transfer roller when the toner image is held between the image carrier and the transfer roller. In the image forming apparatus, the heating unit is controlled based on a detection result of the power output detection unit.
[0013]
The present invention according to claim 3 is characterized in that the power output detection means detects the power output at least twice during one rotation of the transfer roller.
[0014]
According to a fourth aspect of the present invention, there is provided a first image bearing member for carrying a toner image, a rotatable primary transfer roller disposed opposite to the image bearing member via an intermediate transfer member, and the primary transfer member. A primary transfer power source for primarily transferring a toner image on the image carrier to an intermediate transfer member by applying a voltage having a polarity opposite to that of the toner to a roller; and a primary transfer for detecting an output of the primary transfer power source An image forming apparatus comprising: a power output detection unit; a heating unit for heating the primary transfer roller; and a secondary transfer unit for secondary-transferring a toner image on the intermediate transfer member to a transfer material. The heating unit is controlled based on a detection result of the output detection unit.
[0015]
The invention according to claim 5 is characterized in that the primary transfer power supply output detecting means detects the primary transfer power supply output at least twice during one rotation of the primary transfer roller.
[0016]
The present invention according to claim 6 is characterized in that the heating temperature of the heating means is lower than the softening point temperature of the toner.
[0017]
Since the transfer power supply detects the output applied to the transfer roller and controls the heating of the transfer roller based on the result, it is possible to suppress an increase in the resistance of the transfer roller due to a change in the temperature inside the apparatus or a time for energizing the transfer roller. A good image can be formed without causing transfer failure.
[0018]
As described above, the present invention can be summarized into the following configuration by organizing and summarizing the present invention.
[0019]
(1) An image carrier for carrying a toner image, a rotatable transfer roller disposed opposite to the image carrier, a power source for applying a voltage to the transfer roller, and a power output detection for detecting an output of the power source Means for heating the transfer roller, and applying a bias having a polarity opposite to that of the toner by the power supply to the transfer roller when the transfer material is nipped and conveyed between the image carrier and the transfer roller. An image forming apparatus that transfers the toner image on the image carrier to the transfer material by performing
An image forming apparatus, wherein the heating unit is controlled based on a detection result of the power output detection unit.
[0020]
(2) a rotatable transfer roller disposed on an image carrier for carrying a toner image, facing the image carrier via a transfer material carrier, a power supply for applying a voltage to the transfer roller, and a power supply Power supply output detecting means for detecting the output of the transfer material, and a heating means for heating the transfer roller, wherein the transfer material carried and conveyed by the transfer material carrier, and the transfer material carrier is the image carrier and the An image forming apparatus that transfers the toner image on the image carrier to the transfer material by applying a bias having a polarity opposite to that of the toner with the power supply to the transfer roller when the toner image is held by the transfer roller,
An image forming apparatus, wherein the heating unit is controlled based on a detection result of the power output detection unit.
[0021]
(3) The image forming apparatus according to (1) or (2), wherein the power output detection unit detects the power output at least twice during one rotation of the transfer roller.
[0022]
(4) a first image carrier for carrying a toner image, a rotatable primary transfer roller opposed to the image carrier via an intermediate transfer member, and a reverse of the toner on the primary transfer roller. A primary transfer power source for primary transferring a toner image on the image carrier to an intermediate transfer member by applying a polarity voltage, a primary transfer power output detecting means for detecting an output of the primary transfer power source, In an image forming apparatus having a heating unit for heating the primary transfer roller and a secondary transfer unit for secondary-transferring the toner image on the intermediate transfer member to a transfer material, a detection result of the primary transfer power output detection unit An image forming apparatus for controlling the heating unit based on the image data.
[0023]
(5) The image forming apparatus according to (4), wherein the primary transfer power output detection unit detects the primary transfer power output at least twice during one rotation of the primary transfer roller. apparatus.
[0024]
(6) The image forming apparatus according to any one of (1), (2), and (4), wherein a heating temperature of the heating unit is lower than a softening point temperature of the toner.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0026]
<Embodiment 1>
FIG. 1 shows an example of the image forming apparatus according to the first embodiment.
[0027]
The image forming apparatus shown in FIG. 1 includes a drum-type electrophotographic photosensitive member (hereinafter, “photosensitive drum”) 1 as an image carrier. The photosensitive drum 1 is driven to rotate clockwise in FIG. 1 by a driving unit (not shown).
[0028]
After the photosensitive drum 1 is rotated and driven, the surface of the photosensitive drum 1 is uniformly charged by a primary charger 2, and then a laser beam corresponding to an image signal from a host computer (not shown) is irradiated from an exposure device 3 to expose the electrostatic drum. A latent image is formed.
[0029]
The electrostatic latent image is developed (visualized) as a toner image by attaching toner to the developing unit 4. The transfer material 5 is sent by the registration roller 6 so as to be synchronized with the toner image on the photosensitive drum 1. The transfer material 5 is pressed between the transfer roller 7 disposed in contact with the photosensitive drum 1 and the photosensitive drum 1, and the toner image on the photosensitive drum 1 is opposite to the toner charge applied to the transfer roller 7 by the transfer power supply 8. Is transferred to the surface of the transfer material by a transfer bias having a polarity of. The transfer roller 7, the output detection member 9 of the transfer power supply 8, and the heating member 10 for heating the transfer roller 7 will be described later in detail.
[0030]
After transfer of the toner image, the transfer residual toner remaining on the surface of the photosensitive drum 1 is removed by the cleaner 11 and used for the next image formation.
[0031]
On the other hand, the transfer material 5 after transfer of the toner image is transported to a fixing device (not shown) by a drive of a transfer roller through a transport guide (not shown) while carrying the unfixed toner image. Is heated and pressed to be fixed.
[0032]
The transfer roller 7 includes a metal core (not shown) having an outer diameter of 8 mm and a conductive material layer formed on the outer peripheral surface thereof, and has an outer diameter of 16 mm. The conductive material layer has a conductivity of 1 [MΩ] to 100 [MΩ] by using a polymer elastomer such as rubber or urethane or a polymer foam material as a base material and mixing an ionic conductive material into the material. This is adjusted to the resistance region.
[0033]
As the urethane used as the base material of the conductive material layer, as a polyhydroxyl compound, a polyol used for producing a general flexible polyurethane foam or urethane elastomer, that is, a polyether polyol having a polyhydroxyl group at a terminal, a polyester polyol, And a polyether polyol which is a copolymer of the two, and a general polyol such as a so-called polymer polyol obtained by polymerizing an ethylenically unsaturated monomer in the polyol can be used. Examples of the polyisocyanate compound include polyisocyanates which are also used in the production of general flexible polyurethane foams and urethane elastomers, that is, tolylene diisocyanate (TDI), crude TDI, 4,4-diphenylmethane diisocyanate (MDI), crude MDI Use is made of aliphatic polyisocyanates having 2 to 18 carbon atoms, alicyclic polyisocyanates having 4 to 15 carbon atoms, and mixtures and modified products of these polyisocyanates, such as prepolymers obtained by partially reacting with polyols. Can be
[0034]
Further, as the rubber used as the base material of the conductive material layer, natural rubber, nitrile butadiene rubber, chloroprene rubber, styrene butadiene rubber, butadiene rubber, ethylene propylene rubber, isoprene rubber, normal rubber such as polynorbornene rubber or the like Thermoplastic rubbers such as styrene-butadiene-styrene (SBS) and styrene-butadiene-styrene water additive (SEBS) can be used, and liquid polyisoprene rubber can be mixed with these rubbers. Further, those obtained by foaming these rubbers or a copolymer rubber of epichlorohydrin and ethylene oxide can also be used.
[0035]
Examples of the ionic conductive substance added to these base materials include inorganic ionic conductive substances such as sodium perchlorate, calcium perchlorate, and sodium chloride, and further modified denatured aliphatic dimethylethylammonium ethosulfate, stearylammonium acetate, and the like. Organic ionic conductive substances such as lauryl ammonium acetate and octadecyl trimethyl ammonium perchlorate are exemplified, and sodium perchlorate is generally used in general.
[0036]
The metal roller 10 a, which is a component of the heating member 10 that heats the transfer roller 7, has a cylindrical shape and is driven to rotate by the transfer roller 7. The metal roller 10a is heated to 0 to 45 ° C. from the inside of the cylinder by a halogen lamp heater or the like. Both ends of the metal roller 10a are supported by an insulating member such as POM (polyximethylene), and the metal roller 10a is formed to have the same length as the conductive material layer of the transfer roller 7. Is urged toward the transfer roller 7 by contact means (not shown). At this time, a load of 200 g is applied on each side so that the contact pressure against the transfer roller 7 is uniform in the longitudinal direction. The metal roller 10a rotates following the rotation of the transfer roller 7. The above-described halogen lamp heater makes the temperature of the metal roller 10a variable by repeatedly turning on and off by the heating control member 10b. The material of the metal roller 10a is not limited to aluminum, and may be any other metal (for example, copper) as long as the metal has a high thermal conductivity. Any material such as a material made of insulating material may be used.
[0037]
The output detection member 9 of the transfer power supply 8 periodically detects the current by the current detection member 9a, performs the current eight times during one rotation of the transfer roller 7, and averages the eight current detection results by the arithmetic unit 9b. Then, the impedance of the transfer portion is calculated. The heating control member 10b controls the turning on and off of the halogen lamp heater to control the temperature of the metal roller so that the impedance becomes smaller than 100 [MΩ]. This is because the toner on the photosensitive drum 1 or the transfer material 5 is inverted to a polarity inappropriate for transfer near the transfer portion, that is, a polarity opposite to the normal polarity of the toner, and the toner image on the transfer material after passing through the transfer portion. Is determined so as not to be disturbed.
[0038]
The transfer bias (output) from the transfer power supply 8 is controlled at a constant voltage so that a current flowing when a white background portion having no toner image passes through the transfer portion flows at 30 μA in a temperature and humidity environment of 23 ° C. and 50%.
[0039]
<Embodiment 2>
FIG. 2 shows an example of the image forming apparatus according to the second embodiment.
[0040]
The difference from the first embodiment is that, in the first embodiment, the metal roller 10a that comes into contact with the transfer roller 7 and the halogen heater are used as the heating member as shown in FIG. 1, but the second embodiment uses the metal roller 10a. In addition, as shown in FIG. 2, a halogen heater is provided in the cylindrical photosensitive drum 1. That is, the transfer roller 7 is heated via the photosensitive drum 1 that is in contact with the transfer roller 7. The operation and the material and shape of the transfer roller 7 are the same as in the first embodiment.
[0041]
<Embodiment 3>
FIG. 3 shows an example of the image forming apparatus according to the third embodiment.
[0042]
The image forming apparatus shown in FIG. 1 includes a drum-type electrophotographic photosensitive member (hereinafter, “photosensitive drum”) 1 as an image carrier. The photosensitive drum 1 is driven to rotate clockwise in FIG. 1 by a driving unit (not shown).
[0043]
After the photosensitive drum 1 is rotated and driven, the surface of the photosensitive drum 1 is uniformly charged by a primary charger 2, and then a laser beam corresponding to an image signal from a host computer (not shown) is irradiated from an exposure device 3 to expose the electrostatic drum. A latent image is formed.
[0044]
The electrostatic latent image is developed (visualized) as a toner image by attaching toner to the developing unit 4. The transfer material 5 is held by being attracted and held by a not-shown electrostatic attraction member on a transfer belt 12 stretched over a stretch roller, and is sent so as to be synchronized with the toner image on the photosensitive drum 1. The transfer material 5 is pressed in the direction of the photosensitive drum 1 by a transfer roller 7 disposed opposite to the photosensitive drum 1 via a transfer belt, and the toner image on the photosensitive drum 1 is applied to the transfer roller 7 by a transfer power supply 8. The image is transferred onto the transfer material surface by a transfer bias having a polarity opposite to the charge. The transfer roller 7, the output detection member 9 of the transfer power supply 8, and the heating member 10 for heating the transfer roller 7 will be described later in detail.
[0045]
After transfer of the toner image, the transfer residual toner remaining on the surface of the photosensitive drum 1 is removed by the cleaner 11 and used for the next image formation.
[0046]
On the other hand, the transfer material 5 after the transfer of the toner image is carried on the transfer belt 12 while carrying the unfixed toner image, is separated from the transfer belt by a separation portion claw, and passes through a transport guide (not shown). The toner image is conveyed to a fixing device, where the toner image on the surface is heated and pressed to be fixed.
[0047]
The transfer belt 12 is a resin belt of PET or PI having a thickness of 50 to 150 μm, formed in an endless shape, and is driven to rotate in the direction of arrow A. Volume resistivity 10 ⁺⁰⁸ -10 ⁺¹³ It can be used after being adjusted to about [Ω · cm].
[0048]
The transfer roller 7 includes a metal core (not shown) having an outer diameter of 8 mm and a conductive material layer formed on the outer peripheral surface thereof, and has an outer diameter of 16 mm. The conductive material layer has a conductivity of 1 [MΩ] to 100 [MΩ] by using a polymer elastomer such as rubber or urethane or a polymer foam material as a base material and mixing an ionic conductive material into the material. This is adjusted to the resistance region.
[0049]
As the urethane used as the base material of the conductive material layer, as a polyhydroxyl compound, a polyol used for production of a general flexible polyurethane foam or urethane elastomer, that is, a polyether polyol having a polyhydroxyl group at a terminal, a polyester polyol, And a polyether polyol which is a copolymer of the two, and a general polyol such as a so-called polymer polyol obtained by polymerizing an ethylenically unsaturated monomer in the polyol can be used. Examples of the polyisocyanate compound include polyisocyanates which are also used in the production of general flexible polyurethane foams and urethane elastomers, that is, tolylene diisocyanate (TDI), crude TDI, 4,4-diphenylmethane diisocyanate (MDI), crude MDI Use is made of aliphatic polyisocyanates having 2 to 18 carbon atoms, alicyclic polyisocyanates having 4 to 15 carbon atoms, and mixtures and modified products of these polyisocyanates, such as prepolymers obtained by partially reacting with polyols. Can be
[0050]
Further, as the rubber used as the base material of the conductive material layer, natural rubber, nitrile butadiene rubber, chloroprene rubber, styrene butadiene rubber, butadiene rubber, ethylene propylene rubber, isoprene rubber, normal rubber such as polynorbornene rubber or the like Thermoplastic rubbers such as styrene-butadiene-styrene (SBS) and styrene-butadiene-styrene water additive (SEBS) can be used, and liquid polyisoprene rubber can be mixed with these rubbers. Further, those obtained by foaming these rubbers or a copolymer rubber of epichlorohydrin and ethylene oxide can also be used.
[0051]
Examples of the ionic conductive substance added to these base materials include inorganic ionic conductive substances such as sodium perchlorate, calcium perchlorate, and sodium chloride, and further modified denatured aliphatic dimethylethylammonium ethosulfate, stearylammonium acetate, and the like. Organic ionic conductive substances such as lauryl ammonium acetate and octadecyl trimethyl ammonium perchlorate are exemplified, and sodium perchlorate is generally used in general.
[0052]
The transfer roller 7 is heated via the transfer belt 12. The stretching roller is a cylindrical metal roller, and is rotated by the transfer and transfer belt 12. The stretching roller is heated to 0 to 45 ° C. from the inside of the cylinder by a halogen lamp heater or the like. The stretching roller is formed to be longer than the length of the conductive material layer of the transfer roller 7. The above-described halogen lamp heater makes the temperature of the tension roller variable by repeatedly turning on and off by the heating control member 10b. The material of the tension roller is not limited to aluminum, but may be any other metal (for example, copper) as long as the metal has high thermal conductivity.
[0053]
The output detection member 9 of the transfer power supply 8 periodically detects the current by the current detection member 9a, performs the current eight times during one rotation of the transfer roller 7, and averages the eight current detection results by the arithmetic unit 9b. Then, the impedance of the transfer portion is calculated. The heating control member 10b controls the turning on / off of the halogen lamp heater, controls the temperature of the stretching roller, and heats the transfer roller 7 so that the impedance becomes smaller than 100 [MΩ]. This is because the toner on the photosensitive drum 1 or the transfer material 5 is inverted to a polarity inappropriate for transfer near the transfer portion, that is, a polarity opposite to the normal polarity of the toner, and the toner image on the transfer material after passing through the transfer portion. Is determined so as not to be disturbed.
[0054]
The transfer bias (output) by the transfer power supply 8 is controlled at a constant voltage so that a current flowing when a white background portion having no toner image passes through the transfer portion flows at 30 μA in a temperature and humidity environment of 23 ° C. and 50%.
[0055]
<Embodiment 4>
FIG. 4 shows an example of an image forming apparatus according to the fourth embodiment.
[0056]
The image forming apparatus shown in FIG. 1 includes a drum-type electrophotographic photosensitive member (hereinafter, “photosensitive drum”) 1 as an image carrier. The photosensitive drum 1 is driven to rotate clockwise in FIG. 1 by a driving unit (not shown).
[0057]
After the photosensitive drum 1 is rotated and driven, the surface of the photosensitive drum 1 is uniformly charged by a primary charger 2, and then a laser beam corresponding to an image signal from a host computer (not shown) is irradiated from an exposure device 3 to expose the electrostatic drum. A latent image is formed.
[0058]
The electrostatic latent image is developed (visualized) as a toner image by attaching toner to the developing unit 4. The intermediate transfer belt 14 is stretched by a tension roller, and is pressed in the direction of the photosensitive drum 1 by a primary transfer roller 7 disposed opposite the photosensitive drum 1 via the intermediate transfer belt 14, and Is transferred to the surface of the intermediate transfer belt 14 by a transfer bias having a polarity opposite to that of the toner charge applied to the transfer roller 7 by the primary transfer power supply 8. The transfer material 5 is sent by the registration roller 6 so as to be synchronized with the toner image on the intermediate transfer belt 14. The transfer material 5 is pressed in the direction of the ground roller 15b by a secondary transfer roller 15a disposed opposite the ground roller 15b via an intermediate transfer belt 14, and the toner image on the intermediate transfer belt is secondarily transferred by a secondary transfer power supply 16. The image is transferred onto the transfer material surface by a transfer bias applied to the transfer roller 15a and having a polarity opposite to that of the toner charge.
[0059]
The primary transfer roller 7, the output detection member 9 of the primary transfer power supply 8, and the heating member 10 for heating the transfer roller 7 will be described later in detail.
[0060]
The transfer residual toner on the photosensitive drum 1 and the intermediate transfer belt 14 after the transfer of the toner image is removed by the cleaners 11 and 18 and used for the next image formation.
[0061]
On the other hand, the transfer material 5 after the transfer of the toner image is transported to a fixing device (not shown) through a transport guide (not shown) while carrying the unfixed toner image, where the toner image on the surface is heated and pressed. Is fixed.
[0062]
The intermediate transfer belt 14 is a resin belt of PET or PI having a thickness of 50 to 150 μm, formed in an endless shape, and is driven to rotate in the direction of arrow B. Volume resistivity 10 ⁺⁰⁸ -10 ⁺¹³ It can be used after being adjusted to about [Ω · cm].
[0063]
The primary transfer roller 7 includes a metal core (not shown) having an outer diameter of 8 mm and a conductive material layer formed on the outer peripheral surface thereof, and has an outer diameter of 16 mm. The secondary transfer roller 15a includes a metal core (not shown) having an outer diameter of 12 mm and a conductive material layer formed on the outer peripheral surface thereof, and has an outer diameter of 24 mm. The conductive material layer has a conductivity of 1 [MΩ] to 100 [MΩ] by using a polymer elastomer such as rubber or urethane or a polymer foam material as a base material and mixing an ionic conductive material into the material. This is adjusted to the resistance region.
[0064]
As the urethane used as the base material of the conductive material layer, as a polyhydroxyl compound, a polyol used for production of a general flexible polyurethane foam or urethane elastomer, that is, a polyether polyol having a polyhydroxyl group at a terminal, a polyester polyol, And a polyether polyol which is a copolymer of the two, and a general polyol such as a so-called polymer polyol obtained by polymerizing an ethylenically unsaturated monomer in the polyol can be used. Examples of the polyisocyanate compound include polyisocyanates which are also used in the production of general flexible polyurethane foams and urethane elastomers, that is, tolylene diisocyanate (TDI), crude TDI, 4,4-diphenylmethane diisocyanate (MDI), crude MDI Use is made of aliphatic polyisocyanates having 2 to 18 carbon atoms, alicyclic polyisocyanates having 4 to 15 carbon atoms, and mixtures and modified products of these polyisocyanates, such as prepolymers obtained by partially reacting with polyols. Can be
[0065]
Further, as the rubber used as the base material of the conductive material layer, natural rubber, nitrile butadiene rubber, chloroprene rubber, styrene butadiene rubber, butadiene rubber, ethylene propylene rubber, isoprene rubber, normal rubber such as polynorbornene rubber or the like Thermoplastic rubbers such as styrene-butadiene-styrene (SBS) and styrene-butadiene-styrene water additive (SEBS) can be used, and liquid polyisoprene rubber can be mixed with these rubbers. Further, those obtained by foaming these rubbers or a copolymer rubber of epichlorohydrin and ethylene oxide can also be used.
[0066]
Examples of the ionic conductive substance added to these base materials include inorganic ionic conductive substances such as sodium perchlorate, calcium perchlorate, and sodium chloride, and further modified denatured aliphatic dimethylethylammonium ethosulfate, stearylammonium acetate, and the like. Organic ionic conductive substances such as lauryl ammonium acetate and octadecyl trimethyl ammonium perchlorate are exemplified, and sodium perchlorate is generally used in general.
[0067]
The heating of the primary transfer roller 7 is performed via the intermediate transfer belt 14. The tension roller 10a is a cylindrical metal roller, and is driven to rotate with the intermediate transfer belt 14. The stretching roller 10a is heated to 0 to 45 ° C. from the inside of the cylinder by a halogen lamp heater or the like. The tension roller 10 a is formed to be longer than the length of the conductive material layer of the primary transfer roller 7. The above-mentioned halogen lamp heater makes the temperature of the tension roller 10a variable by repeatedly turning on and off by the heating control member 10b. The material of the tension roller 10a is not limited to aluminum, but may be any other metal (for example, copper) as long as the metal has high thermal conductivity.
[0068]
The output detection member 9 of the primary transfer power supply 8 periodically detects the current by the current detection member 9a, performs the current eight times during one rotation of the transfer roller 7, and performs the current detection result eight times by the arithmetic unit 9b. And then calculate the impedance of the transfer section. The heating control member 10b controls the turning on / off of the halogen lamp heater, controls the temperature of the stretching roller 10a, and heats the transfer roller 7 so that the impedance becomes smaller than 100 [MΩ]. This is because the toner on the photosensitive drum 1 or the transfer material 5 reverses to a polarity inappropriate for transfer near the primary transfer portion, that is, a polarity opposite to the normal polarity of the toner, so that the toner on the transfer material after passing through the transfer portion is transferred. The impedance is determined so as not to disturb the toner image.
[0069]
The transfer bias (output) by the primary transfer power supply 8 is controlled at a constant voltage so that a current flowing when a white background portion having no toner image passes through the transfer portion flows at 30 μA in a temperature and humidity environment of 23 ° C. and 50%. Similarly, the transfer bias (output) from the secondary transfer power supply 16 is controlled at a constant voltage so that a current flowing when a white background portion having no toner image passes through the transfer portion flows at 60 μA in a temperature and humidity environment of 23 ° C. and 50%. .
[0070]
Although not shown in FIG. 4, the impedance of the secondary transfer section is controlled by controlling the heating means of the secondary transfer roller 15a based on the detection result of the output of the secondary transfer power supply 16 as in the first embodiment. It is also possible.
[0071]
【The invention's effect】
As described above, according to the present invention, the transfer power supply detects the output applied to the transfer roller, and controls the heating of the transfer roller based on the result. It is possible to form a high-quality image by suppressing an increase in resistance of the transfer roller due to the energization time, preventing transfer failure.
[Brief description of the drawings]
FIG. 1 shows a first embodiment of the present invention.
FIG. 2 is a diagram showing a second embodiment of the present invention;
FIG. 3 is a diagram showing a third embodiment of the present invention;
FIG. 4 is a diagram showing a fourth embodiment of the present invention.
FIG. 5 illustrates a conventional example.
FIG. 6 illustrates a problem.
FIG. 7 illustrates a problem.
[Explanation of symbols]
1 Photosensitive drum
2 Primary charger
3 Exposure equipment
4 Developing device
5 Transfer material
6 Registration roller
7 Transfer roller
8 Transfer power supply
9 Output detection member
9a Current detection member
9b arithmetic unit
10 heating members
10a tension roller
10b Heating control member
11 Cleaner
12 Transfer belt
14 Intermediate transfer belt
15a Secondary transfer roller
15b Ground roller
16 Secondary transfer power supply
18 Cleaner
19 Transfer nip
20 Gap near transfer nip

Claims (6)

An image carrier for carrying a toner image, a rotatable transfer roller disposed opposite to the image carrier, a power supply for applying a voltage to the transfer roller, and power supply output detection means for detecting an output of the power supply; Having a heating means for heating the transfer roller, by applying a bias having a polarity opposite to that of the toner with the power supply to the transfer roller when the transfer material is nipped and conveyed between the image carrier and the transfer roller. An image forming apparatus for transferring the toner image on the image carrier to the transfer material,
An image forming apparatus, wherein the heating unit is controlled based on a detection result of the power output detection unit. An image carrier that carries the toner image, a rotatable transfer roller facing the image carrier via a transfer material carrier, a power supply that applies a voltage to the transfer roller, and an output of the power supply. A power supply output detecting means for detecting, and a heating means for heating the transfer roller, wherein the transfer material carried and conveyed by the transfer material carrier and the transfer material carrier is attached to the image carrier and the transfer roller. An image forming apparatus that transfers the toner image on the image carrier to the transfer material by applying a bias having a polarity opposite to that of the toner with the power supply to the transfer roller when being nipped,
An image forming apparatus, wherein the heating unit is controlled based on a detection result of the power output detection unit. 3. The image forming apparatus according to claim 1, wherein the power output detection unit detects the power output at least twice during one rotation of the transfer roller. A first image carrier for carrying a toner image, a rotatable primary transfer roller opposed to the image carrier via an intermediate transfer member, and a voltage having a polarity opposite to that of the toner applied to the primary transfer roller. A primary transfer power supply for primary transferring the toner image on the image bearing member to the intermediate transfer member by applying an image, a primary transfer power supply output detecting means for detecting an output of the primary transfer power supply, An image forming apparatus comprising: a heating unit for heating a transfer roller; and a secondary transfer unit for secondary-transferring a toner image on the intermediate transfer body to a transfer material.
An image forming apparatus, wherein the heating unit is controlled based on a detection result of the primary transfer power output detection unit. 5. The image forming apparatus according to claim 4, wherein the primary transfer power output detection unit detects the primary transfer power output at least twice during one rotation of the primary transfer roller. The image forming apparatus according to claim 1, wherein a heating temperature of the heating unit is lower than a softening point temperature of the toner.

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