JP5434298B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  In the developing device incorporated in the image forming apparatus, the storage tank is partitioned into a first storage chamber adjacent to the developing roll and a second storage chamber adjacent to the first storage chamber. There is one that moves the developer while stirring between the two storage chambers (see, for example, Patent Document 1).

JP-A-9-204105 (FIG. 5)

  An object of the present invention is to provide an image forming apparatus in which generation of low-charged toner and reverse polarity toner in a developer is suppressed.

An image forming apparatus according to claim 1 is provided.
An image carrier that holds an image on which an image is formed;
A latent image forming unit that forms an electrostatic latent image on the surface of the image carrier;
A toner container that contains toner therein;
An independent member in which the surface potential is aligned with the image carrier in the direction in which the surface on which the latent image is formed by the latent image forming unit extends, and is independent of the surface potential of the image carrier;
A charger for charging the surface of the independent member;
A developer containing the charged toner is contained in the latent image formed on the surface of the image holding member to form a toner image by attaching the charged toner,
Adjacent to both the image carrier and the independent member, the image carrier and the independent member have a potential difference. The developer is held on the surface and rotated to rotate the developer. A developing roll transported to a developing area facing the body and a facing area facing the independent member; and the developer is accommodated in the developing roll adjacent to the developing roll and extending along the rotation axis of the developing roll. The developer is supplied to the developing roll. The first developer is conveyed along the rotation axis in a first direction from the far side from the independent member toward the independent member while stirring the developer. A container and a moving port that is adjacent to the first container and extends alongside the first container and that has a moving port for moving the developer to and from the first container are provided at both ends. Contains developer and is supplied with toner. A second storage unit that conveys the developer and the toner in a second direction opposite to the first direction while stirring and mixing the toner, and a toner supply that supplies the toner from the toner storage unit to the second storage unit And a developing device that changes the supply position in a direction along the second direction when the toner supply unit is instructed to change the supply position for supplying toner to the second storage unit. And a change instructing unit that instructs the supply position changing mechanism to change the supply position to a position corresponding to the supply amount of the toner to the second storage unit;
It is provided with.

An image forming apparatus according to claim 2
In the developing roll, a developing unit that transports the developer to the developing region and a non-developing unit that transports the developer to the opposing region are separated from each other. It is what is provided.

An image forming apparatus according to claim 3
The independent member is a potential difference that generates an electric field between the developing roll and the independent member in the same direction as the direction of the electric field generated between the developing roll and the image carrier. And an image carrier having a potential difference larger than that between the developing roller and the image carrier.

An image forming apparatus according to claim 4
The independent member is a potential difference that generates an electric field between the developing roll and the independent member in the same direction as the direction of the electric field generated between the developing roll and the image carrier. And an image carrier having a potential difference smaller than that between the developing roller and the image carrier.

An image forming apparatus according to claim 5
The independent member generates a potential difference between the developing roller and the developing roller that generates an electric field opposite to the direction of the electric field generated between the developing roller and the image carrier. It is characterized by having it in between.

An image forming apparatus according to claim 6
An exposure unit that irradiates the surface of the independent member charged by the charger with exposure light to form a potential distribution on the surface;
The independent member has an electric field in the same direction as the electric field generated between the developing roll and the image carrier between the developing roll and the independent member. A first potential difference generated between the developing roller and the image carrier, and a direction of the electric field generated between the developing roller and the image carrier. And a second potential difference that generates an electric field in the opposite direction between the developing roll and the independent member.

An image forming apparatus according to claim 7 is provided.
In the developing roll, a developing unit that transports the developer to the developing region and a non-developing unit that transports the developer to the opposing region are separated from each other. To be granted,
By applying a potential to the non-developing portion, a potential difference between the non-developing portion and the independent member is greater than the potential difference between the developing portion and the image carrier, and the developing portion and the image A large difference generation potential applying unit that generates an electric field in the same direction as the direction of the electric field generated between the holding body and the holding body is provided.

An image forming apparatus according to claim 8 is provided.
In the developing roll, a developing unit that transports the developer to the developing region and a non-developing unit that transports the developer to the opposing region are separated from each other. To be granted,
By applying a potential to the non-developing portion, a potential difference smaller than the potential difference between the developing portion and the image carrier between the non-developing portion and the independent member, and the developing portion and the image A small difference generation potential applying unit that generates an electric field in the same direction as the electric field generated between the holding body and the holding body is provided.

An image forming apparatus according to claim 9 is provided.
In the developing roll, a developing unit that transports the developer to the developing region and a non-developing unit that transports the developer to the opposing region are separated from each other. To be granted,
By applying a potential to the non-developing portion, an electric field opposite to the direction of the electric field generated between the developing portion and the image carrier is generated between the non-developing portion and the independent member. A reverse electric field generation potential applying unit is provided.

An image forming apparatus according to claim 10 is provided.
In the developing roll, a developing unit that transports the developer to the developing region and a non-developing unit that transports the developer to the opposing region are separated from each other. To be granted,
By applying a first potential to the non-developing portion, a potential difference between the non-developing portion and the independent member is smaller than the potential difference between the developing portion and the image carrier, and the developing portion And a small difference generating potential applying section that generates an electric field in the same direction as the electric field generated between the non-developing section and the non-developing section by applying a second potential to the non-developing section. Between this independent member, this first potential that also serves as a reverse electric field generation potential applying unit that generates an electric field opposite to the direction of the electric field generated between the developing unit and the image carrier. A potential applying unit that can be switched to the second potential is provided.

An image forming apparatus according to claim 11 is provided.
The change instructing unit instructs to change the supply position to the upstream side in the second direction as the image density increases in accordance with the image density of the latent image formed by the latent image forming unit. It is characterized by that.

An image forming apparatus according to claim 12 is provided.
The change instructing unit changes the supply position to the upstream side in the second direction as the frequency increases according to the frequency of supply of the toner from the toner supply unit to the second storage unit. It is characterized by instructing the position changing mechanism.

An image forming apparatus according to claim 13 is provided.
The change instructing unit changes the supply position to the upstream side in the second direction as the supply time increases in accordance with a supply time in which the toner supply unit supplies the toner per predetermined time. Instructing the supply position changing mechanism.

An image forming apparatus according to claim 14 is provided.
The toner supply unit has a plurality of supply paths reaching each of a plurality of locations along the second direction in the second storage unit, and each of the plurality of supply paths has the toner at each of the plurality of locations. Is to supply
The supply position changing mechanism has a plurality of switches that open and close each of the plurality of supply paths, and opens and closes the switches according to instructions,
The change instructing unit instructs the supply position changing mechanism to select a switch corresponding to the amount of toner supplied to the second storage unit among the plurality of switches as an instruction to change the supply position. It is characterized by being.

An image forming apparatus according to claim 15 is provided.
The toner supply unit is provided in each of the plurality of supply paths reaching the plurality of locations along the second direction in the second storage unit, and the toner is supplied to the toner supply unit. It has a plurality of transport mechanisms that transport each of the plurality of locations along the road,
The supply position changing mechanism drives a transport mechanism according to an instruction among the plurality of transport mechanisms,
The change instructing unit instructs the supply position changing mechanism to specify a transport mechanism corresponding to the amount of toner supplied to the second storage unit among the plurality of transport mechanisms as an instruction to change the supply position. It is characterized by being.

    According to the developing device of the first aspect, it is possible to suppress the generation of low-charge toner and reverse polarity toner in the developer.

  According to the image forming apparatus of the second aspect, it is possible to cope with the removal of different types of deteriorated toner.

  According to the image forming apparatus of the third aspect, the overcharged toner of the deteriorated toner in the developer is removed.

  According to the image forming apparatus of the fourth aspect, the low-charged toner is removed from the deteriorated toner in the developer.

  According to the image forming apparatus of the fifth aspect, the reverse polarity toner of the deteriorated toner in the developer is removed.

  According to the image forming apparatus of the sixth aspect, the low-charged toner and the reverse polarity toner among the deteriorated toners in the developer are simultaneously removed.

  According to the image forming apparatus of the seventh aspect, it is possible to reliably obtain a potential state in which the overcharged toner of the deteriorated toner in the developer is removed.

  According to the image forming apparatus of the eighth aspect, it is possible to reliably obtain a potential state in which the low-charged toner out of the deteriorated toner in the developer is removed.

  According to the image forming apparatus of the ninth aspect, it is possible to reliably obtain a potential state in which the reverse polarity toner of the deteriorated toner in the developer is removed.

  According to the image forming apparatus of the tenth aspect, it is possible to selectively remove each of the low-charged toner and the reverse polarity toner among the deteriorated toner.

  According to the image forming apparatus according to the eleventh, twelfth, and thirteenth aspects, it is possible to more reliably suppress the generation of low-charged toner and reverse polarity toner in the developer.

  According to the image forming apparatus of the fourteenth and fifteenth aspects, the change of the new toner supply position by the change instruction unit can be realized with a simple configuration.

1 is a schematic configuration diagram of a printer. FIG. 2 is a perspective view from the laser exposure device side of the developing device shown in FIG. 1. It is sectional drawing of the developing device shown in FIG. FIG. 3 is a diagram illustrating details of a toner supply device. It is a figure which shows the mode of irradiation of the laser exposure light from a laser exposure device. It is a figure which shows the electric potential relationship of the developing device etc. of the printer of 2nd Embodiment. It is a figure shown about the irradiation range of the laser exposure light from a laser exposure device. It is a figure which shows the detail of the toner supply apparatus with which the printer of 4th Embodiment is equipped. It is a figure which shows the mode of the voltage application to the conveyance roll with which the printer of 4th Embodiment is equipped, and the image development roll. It is a figure which shows the detail of the toner supply apparatus with which the printer of 5th Embodiment is equipped.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of a printer.

  A printer 1 shown in FIG. 1 includes a photoconductor 10, a charger 11 that applies a charge to the surface of the photoconductor 10, a laser exposure device 12 that generates laser light based on image data transmitted from the outside, and the like. , A developing device 13 that stores a developer containing toner, a paper cassette 16 that stores recording paper, a paper transport device 17 that pulls out and transports recording paper from the paper cassette 16, and transports a toner image in the direction of arrow B. A transfer roll 14 for transferring onto the recording paper, a fixing device 15 for fixing the toner image on the recording paper by heating and pressurizing the toner image on the recording paper, and a center for controlling the operation of these parts. A control unit 100 and a cleaning device 50 for cleaning the surface of the photoreceptor roll 10 are provided. The developing device 13 includes a developing roll 133 that conveys the developer to a region between the developing device 13 and the developing device 13 while rotating to face the photosensitive member 10. The adhering matter adhering to the portion of the photoreceptor roll 10 where the transfer of the toner image has been completed is downstream of the transfer roll 14 in the direction of arrow A and upstream of the charger 11, and the photoreceptor 10 is rotated. It is removed by scraping the cleaning blade 51 whose tip contacts the entire width along the center. The removed deposit is stored in the deposit storage box 52. In addition to the toner, the developer contained in the developing unit 13 includes a magnetic carrier that is a charge-providing particle and a magnetic particle that frictionally charges the toner by friction with the toner, and controls the chargeability of the toner. External additives such as charge control agents are included.

  The printer 1 is a first embodiment of the image forming apparatus of the present invention. The photosensitive member 10 corresponds to an example of an image carrier that holds an image formed on the surface, and the combination of the charger 11 and the laser exposure device 12 is an electrostatic latent image on the carrier. This corresponds to an example of a latent image forming unit that forms the image.

  Here, the flow of the image forming operation in the printer 1 will be briefly described.

  In the printer 1 shown in FIG. 1, charge is applied to the surface of the photoconductor 10 rotating in the direction of arrow A by the charger 11, and image data transmitted from the outside to the surface of the photoconductor 10 to which the charge is applied. By irradiating the laser beam based on the above with the laser exposure device 12, an electrostatic latent image is formed on the surface of the photoconductor 10. Although the mechanism will be described later, the developer accommodated in the developing device 13 is supplied to the surface of the developing roll 133 and is transported to a region between the developing roll 133 and the photoreceptor 10, and in the transported developer. As the toner adheres onto the latent image, the electrostatic latent image on the surface of the photoreceptor 10 is developed. The toner image obtained by this development is transferred onto the recording paper conveyed in the direction of arrow B by the transfer roll 14, and the toner image on the recording paper is melted by the fixing device 15 that heats and pressurizes the toner image. It is fixed on the recording paper. The printer 1 is a monochrome image dedicated machine, but the present invention may be applied to a color image machine.

  In the printer 1 of the present embodiment, a low-temperature fixing toner that can be fixed at a low temperature is used to suppress heat generation in the fixing device 15. Details of the low-temperature fixing toner will be described later. Further, the printer 1 of the present embodiment is provided with a toner supply device 2 that supplies new toner to the developing device 13, and details thereof will be described later.

  FIG. 2 is a perspective view of the developing device shown in FIG. 1 from the laser exposure device side.

  FIG. 2 shows a developing device 13 that includes a developing roll 133, a developer storage tank 132 that stores the developer, and an agitation transport member 131 that stirs and transports the developer inside the developer storage tank 132. ing.

  The developer storage tank 132 has a first storage chamber 132a that is adjacent to the development roll 133 and is supplied with new toner by a wall 1321 that extends in parallel with the development roll 133, and the first storage chamber 132a. And the second storage chamber 132b adjacent to each other.

  In each of the first storage chamber 132a and the second storage chamber 132b, one agitation transport member 131 is provided. Specifically, the agitation transport member 131 includes a spiral fin around the rod. It has a provided structure. As the agitating and conveying member 131 provided in each of the first accommodation chamber 132a and the second accommodation chamber 132b rotates in the opposite directions, the developer accommodated in the developer accommodating tank 132 is agitated around the wall 1321. Cycle counterclockwise. Inside the developer storage tank 132, the toner and the magnetic carrier are agitated by the agitating and conveying member 131, so that the toner is negatively charged and the magnetic carrier is positively charged. For this reason, the negatively charged toner adheres electrostatically to the magnetic carrier. As a result, the toner and the magnetic carrier are naturally integrated inside the developer storage tank 132.

  Further, in FIG. 2, the developing roller 133 is provided coaxially with the developing roller 133 at the most downstream position in the developer transport direction in the first storage chamber 132 a of the developer storage tank 132 immediately before new toner is supplied. A conveyance roll 134, an adsorption roll 400 that faces the conveyance roll 134 and is provided coaxially with the photoreceptor 10, and a charging device 500 that charges the adsorption roll 400 are shown.

  The transport roll 134 is separate from the developing roll 133 and has the same diameter, the same material, and the same structure as the developing roll 133, although the applied voltage is different from that of the developing roll 133.

  The suction roll 400 has the same diameter, the same material, and the same structure as the photoconductor 10.

  In the printer 1, an image is formed by the developing roll 133 and the photoconductor 10 facing the developing roll 133, while the transport roll 134 is formed by the suction roll 400 and the transport roll 134 facing the suction roll 400. The deteriorated toner is extracted from the developer held on the surface. Note that the surface of the suction roll 400 is not exposed and the sheet is not transported. Further, the transport roll 134 corresponds to an example of a non-developing portion referred to in the present invention, and the suction roll 400 corresponds to an example of an independent member referred to in the present invention. The charging device 500 corresponds to an example of the charger according to the present invention. Hereinafter, the adsorption mechanism of the deteriorated toner will be described.

  FIG. 3 is a cross-sectional view of the developing device shown in FIG.

  Part (a) of FIG. 3 shows a state in which the AA cross section of the developing unit or the like shown in FIG. 2 is viewed in the direction of the arrow, and part (b) of FIG. 3 shows the state shown in FIG. A state in which the BB cross section of the developing device or the like viewed in the direction of the arrow is shown.

  The developing roll 133 shown in FIG. 3A has a cylindrical member 1331 that rotates in the direction of arrow C, and a permanent magnet roll 1332 that is fixed inside the cylindrical member 1331 independently of the cylindrical member 1331. ing. The permanent magnet roll 1332 has a plurality of magnetic poles arranged in the circumferential direction of the cylindrical member 1331 and has a magnetic force distribution that regulates adsorption and release of the developer.

  A part of the peripheral surface of the cylindrical member 1331 exists in the developer accommodating tank, and the others exist outside the developer accommodating tank. Therefore, when the cylindrical member 1331 rotates, the peripheral surface of the cylindrical member 1331 passes through the developer storage tank. The developer is supplied to the peripheral surface passing through the developer storage tank by the magnetic force distribution of the permanent magnet roll 1332 provided inside the cylindrical member 1331. The cylindrical member 1331 conveys the supplied developer to a developing region 1301a formed between the photosensitive member 10 and the cylindrical member 1331.

  The photoreceptor 10 shown in part (a) of FIG. 3 is a portion where the entire surface is once charged to −720 V by the charger 11 and then an electrostatic latent image is formed by exposure by the laser exposure device 12. Is about −300V. On the other hand, a voltage is applied to the developing roll 133 so that the potential becomes −600V. The toner that is electrically attached to the magnetic carrier held on the developing roll 133 and is conveyed to the first region 1301a between the photoreceptor 10 and the developing roll 133 is charged with a negative polarity in the developer containing tank 132. Therefore, the electrostatic latent image is overcome by the electric field (potential difference is 300 V) from the electrostatic latent image portion of the photoconductor 10 toward the developing roll 133 to overcome the electrostatic attractive force with the magnetic carrier. A toner image is formed on the photoreceptor 10. At this time, the magnetic carrier remains on the developing roll 133 while being attracted to the surface of the cylindrical member 1331 of the developing roll 133 by a magnetic force, and is collected into the developer containing tank 132. The first area 1301a corresponds to an example of a developing area referred to in the present invention, and the developing roll 133 corresponds to an example of a developing section referred to in the present invention.

  Here, in the printer 1, in a situation where image formation with a low image density continues for a long time and new toner is not supplied much, external additive on the toner surface is obtained by repeated stirring of the existing toner and the magnetic carrier. Tends to be buried or detached from the toner surface, the toner charging performance inside the developing device is rapidly deteriorated. If such deterioration is left unattended, a narrow toner charge amount distribution would be widened. In particular, the deterioration is remarkable in the case of the above-described low-temperature fixing toner. For example, when image formation with a high image density is performed after such a charge amount distribution is generated, a large amount of new toner is supplied to the second storage chamber 132b of the developer storage tank 132. In this case, the charge of the overcharged toner among the deteriorated toner stored in the developer storage tank 132 is quickly taken away by the newly supplied toner, and the developer storage tank 132 contains The newly supplied toner is deprived of electric charge, and the toner is low-charged toner whose increase in charge amount is slow due to friction with the magnetic carrier due to deterioration. A state in which extremely toner is mixed is generated. When the developer in which these are mixed is held on the developing roll 133 and used for development, the low charge toner having a weak electrostatic connection with the magnetic carrier due to insufficient charge amount is separated from the magnetic carrier. However, the cloud does not adhere to the latent image, and the reverse polarity toner that has turned to the opposite polarity adheres to the background area that is a portion other than the latent image formed on the surface of the photoconductor 10 to cause fogging. To do.

  Therefore, in the printer 1 of the present embodiment, as one of the measures for suppressing the occurrence of these problems, the toner and magnetic carrier in the developer storage tank 132 are changed according to the amount of new toner supplied to the developer storage tank 132. By adjusting the friction opportunity, deterioration of the charging performance of the toner is suppressed. Specifically, as described below, the supply position of new toner to the second storage chamber 132 b of the developer storage tank 132 is variable by the toner supply device 2.

  First, the structure of the toner supply position will be described. The description of part (b) in FIG. 3 will be given later.

  FIG. 4 is a diagram illustrating details of the toner supply device.

  A toner supply device 2 shown in FIG. 4 includes a toner cartridge 21 in which toner is stored, a vertical main supply pipe 22 to which the toner cartridge 21 is attached and detached, and a developer storage tank whose end is connected to the vertical main supply pipe 22. The horizontal main supply pipe 23 extends along the wall 1321 of the 132, and the first sub supply pipe 24 and the first secondary supply pipe 24 extend from the horizontal main supply pipe 23 to the second storage chamber 132b. The second sub supply pipe 25, the third sub supply pipe 26, the fourth sub supply pipe 27, and the control unit 20 that controls the entire toner supply apparatus 2 are provided.

  The vertical main supply pipe 22 has a built-in first main transport member 221 having a structure in which a spiral fin is provided around the rod for sending the toner contained in the toner cartridge 21 to the horizontal main supply pipe 23. In addition, a first main motor 222 that rotates the first main transport member 221 is attached. A worm gear 2221 is attached to the rotation shaft of the first main motor 222 and meshes with a gear 2211 provided at the rod end of the first main transport member 221. Further, the driving of the first main motor 222 is controlled by the control unit 20. For this reason, when the first main motor 222 rotates according to the rotation instruction from the control unit 20, the first main transport member 221 also rotates, and the toner contained in the toner cartridge 21 is supplied to the horizontal main supply pipe 23.

  The horizontal main supply pipe 23 also includes a second main transport member 231 having a structure in which spiral fins are provided around the rod, and a second main motor 232 that rotates the second main transport member 231. Is attached. Further, the rotating shaft of the second main motor 232 and the rod end of the second main transport member 231 are connected. For this reason, when the second main motor 232 whose drive is controlled by the control unit 20 as in the case of the first main motor 222 is rotated by a rotation instruction from the control unit 20, the second main transport member 231 is also rotated, and the toner cartridge The toner supplied from 21 through the vertical main supply pipe 22 is conveyed inside the horizontal main supply pipe 23.

  The first sub-supply pipe 24, the second sub-supply pipe 25, the third sub-supply pipe 26, and the fourth sub-supply pipe 27 are connected to the second storage chamber from four locations of the horizontal main supply pipe 23 as shown in FIG. It extends to four locations from the upstream side to the downstream side in the developer conveyance direction in 132b. Hereinafter, a range in which the first sub supply pipe 24, the second sub supply pipe 25, the third sub supply pipe 26, and the fourth sub supply pipe 27 are arranged is referred to as a supplyable range R. In the supplyable range R, the position where the first sub supply pipe 24 is disposed is the most upstream position P1 in the developer transport direction in the second storage chamber 132b, and the fourth sub supply pipe 27 is disposed. The position is the most downstream position P2.

  Each of the first sub supply pipe 24, the second sub supply pipe 25, the third sub supply pipe 26, and the fourth sub supply pipe 27 includes a first electromagnetic valve 241 and a valve body 2511 having a valve body 2411 therein. A second electromagnetic valve 251 having a valve body 2611, a third electromagnetic valve 261 having a valve body 2611, and a fourth electromagnetic valve 271 having a valve body 2711. The operations of the electromagnetic valves 241, 251, 261, and 271 are controlled by the control unit 20 of the toner supply device 2, and the valve bodies 2411, 2511, 2611, and 2711 are driven according to instructions transmitted from the control unit 20. Each of the first sub supply pipe 24, the second sub supply pipe 25, the third sub supply pipe 26, and the fourth sub supply pipe 27 is set in an open state or a closed state.

  In this printer 1, the supply of new toner to the second storage chamber 132b of the developer storage tank 132 is controlled by the central control unit 100 so as to keep the toner concentration in the developer storage tank constant. Two types of instruction signals, a toner supply start instruction and a toner supply stop instruction, are transmitted from the central control unit 100 shown in 1 to the control unit 20 of the toner supply device 2.

  When receiving a toner supply start instruction from the central control unit 100, the control unit 20 rotates the first main motor 222 and the second main motor 232 to drive the first main transport member 221 and the second main transport member 231, When a toner supply stop instruction is received from the central control unit 100, the first main motor 222 and the second main motor 232 are stopped and the first main transport member 221 and the second main transport member 231 are stopped. The central control unit 100 always issues a toner supply stop instruction after a predetermined time from issuing the toner supply start instruction. That is, one supply time and supply amount are always constant. In addition, the central control unit 100 performs a period from the previous toner supply stop instruction to the next toner supply start instruction when the high-density image formation is continued in the printer 1 as compared with the case where the low-density image formation is continuous. Narrow the time interval to increase the toner supply frequency.

  The control unit 20 sequentially measures the time interval from the previous toner supply stop instruction from the central control unit 100 to the subsequent toner supply start instruction, and the measured time interval is traced back from the most recent measurement. The batch is held in a memory (not shown).

  The control unit 20 calculates an average value of five time intervals held in the memory every time a toner supply start instruction is received from the central control unit 100. Further, the control unit 20 determines which range of the four numerical ranges (A, B, C, D) divided by the three boundary values belongs to the average value.

  When it is determined that the average value of the five time intervals belongs to the numerical value range A having the smallest numerical value among the four numerical value ranges A, B, C, and D, the toner supply frequency is high, A high-density image formation is performed. Accordingly, since the amount of toner consumed is large, it is considered that the new toner supplied to the developer storage tank 132 is used for image formation without much agitation and conveyance in the developer storage tank 132. Therefore, in such a case, there is no fear that the toner deteriorates due to too many opportunities for friction with the magnetic carrier. Therefore, the new toner is supplied to the most upstream position P1 in the supply possible range R in the transport direction of the developer transported through the second storage chamber 132b of the developer storage tank 132. Such a supply is realized by the control unit 20 opening only the first sub supply pipe 24 and closing the other sub supply pipes, and thus the toner is supplied to the most upstream position P1. This avoids a shortage of charge due to too few opportunities for friction.

  On the other hand, when it is determined that the average value of the five time intervals belongs to the numerical value range D having the largest numerical value among the above four numerical value ranges, the toner supply frequency is low and the density is low. The formation will be done. Therefore, since the amount of toner consumption is small, it is considered that it takes time until new developer is supplied to the developer storage tank 132 and used for image formation. Therefore, in such a case, in order to avoid toner deterioration due to excessive friction with the magnetic carrier, new toner is transferred to the second storage chamber 132b of the developer storage tank 132. To the most downstream position P2 of the supplyable range R in the transport direction. Such supply is realized by the control unit 20 opening only the fourth sub supply pipe 27 and closing the other sub supply pipes, and thus the toner is supplied to the most downstream position P2. However, since it takes time from supply to use, shortage of charge due to too few friction opportunities is avoided.

  In addition, when it is determined that the average value of the five time intervals belongs to the numerical value range B of the above four numerical ranges, the control unit 20 opens only the second sub supply pipe 25 and When it is determined that the average value of the time interval belongs to the numerical value range C of the above four numerical value ranges, the control unit 20 opens only the third sub supply pipe 26. By such an open mode of the sub supply pipe, the supply to the supply position according to the supply frequency of the toner is realized.

  When the average value of the time intervals from the most recent five time intervals from the latest toner supply stop instruction to the subsequent toner supply start instruction from the central control unit 100 is large, that is, when low-density image formation is performed In this case, the toner consumption is small and there is a time delay before it is used for image formation, so that a sufficient charge amount can be obtained, but the toner charging performance deteriorates due to friction with the magnetic carrier for a long time. In this printer 1, in the case where the average value of the time intervals for five times going back from the latest is large, the supply possible range in the transport direction of the developer in the second storage chamber 132b of the developer storage tank 132 is possible. By supplying new toner to the downstream side of R, the chance of friction with the magnetic carrier is suppressed by that distance compared to the case of supplying to the upstream side. Deterioration is suppressed.

  On the other hand, when the average value of the time intervals for the last 5 times is small, that is, when high-density image formation is performed, the amount of toner consumption is large, and it does not take time until it is used for image formation. In addition, although the toner charging performance is hardly deteriorated due to friction with the magnetic carrier, there is no time delay until the toner is used for image formation, so that new toner is supplied to the second storage chamber 132b of the developer storage tank 132. When supplied to the downstream side of the possible range R, there is a possibility that a sufficient amount of charge cannot be secured before it is used for image formation due to insufficient friction with the magnetic carrier. Therefore, in the printer 1 according to the present embodiment, when the average value of the time intervals for the five times going back from the most recent time is small, the printer 1 in the second storage chamber 132b is newly provided upstream of the supplyable range R in the developer transport direction. As compared with the case where the toner is supplied and supplied to the downstream side, the amount of electrification is ensured by securing the chance of friction with the magnetic carrier by the distance. In other words, the printer 1 prevents the toner from deteriorating due to friction between the toner and the magnetic carrier while preventing the toner from expanding the charge amount distribution while securing the charge amount necessary for the toner. This suppresses the occurrence of overcharged toner that causes generation of low-charged toner and reverse polarity toner without adversely affecting image quality. In FIG. 4, the valve body 2511 of the second electromagnetic valve 251 of the second sub supply pipe 25 is retracted from the inside of the second sub supply pipe 25, thereby opening the second sub supply pipe 25. As the valve bodies 2411, 2611, 2711 of the solenoid valves 241, 261, 271 advance into the sub supply pipes, the first sub supply pipe 24, the third sub supply pipe 26, and the fourth sub supply pipe 27 are formed. The state of being closed is shown. The toner cartridge 21, the vertical main supply pipe 22, the horizontal main supply pipe 23, and the sub supply pipes 24 to 27 correspond to an example of the toner supply unit according to the present invention, and the sub supply pipes 24 to 27 are the supply path. It corresponds to an example. The control unit 20 corresponds to an example of a change instruction unit according to the present invention. Further, each of the electromagnetic valves 241, 251, 261, 271 corresponds to an example of a switch according to the present invention, and the combination of the electromagnetic valves 241, 251, 261, 271 is an example of a supply position changing mechanism according to the present invention. Equivalent to.

  Next, as another countermeasure for suppressing the generation of cloud and fog caused by the low-charged toner and the reverse polarity toner that are deteriorated toners, the printer 1 according to the present embodiment causes the low-charge toner and the reverse-polarity toner to be generated. The deteriorated toner is removed from the developer.

  Specifically, in the printer 1 of the present embodiment, the developer storage tank 132 is obtained by adsorbing and collecting the overcharged toner by the independent member 400 facing the transport roll 134 as described below and by the cleaning device 50. The overcharged toner is removed from the toner.

  This is because, when low-density image formation continues and the toner deteriorates due to friction with the magnetic carrier, the toner charge amount distribution, which is within a narrow range before deterioration, gradually spreads over a wide range. This is because when a new toner is supplied, the charge of the overcharged toner in the charge amount distribution spread over a wide range is rapidly deprived by the new toner, resulting in the generation of a low charge toner or a reverse polarity toner. . In the printer 1, in the flow of the developer that is agitated and transported inside the developer storage tank 132, before the most upstream position P 1 in the supplyable range R to which new toner is supplied, The toner on the overcharge side can be removed. As a result, rapid charge transfer to new toner is hindered, and generation of these lowly charged toner and reverse polarity toner is suppressed. Here, returning to part (b) of FIG. 3, the description will be continued.

  Part (b) of FIG. 3 shows a developer storage tank 132 and a transport roll 134, which, like the development roll 133, has a rotating cylindrical member 1331 and an internal permanent magnet. A roll 1332. The rotating cylindrical member 1331 of the transport roll 134 is supplied with developer while passing through the developer storage tank due to the magnetic distribution of the internal permanent magnet roll 1332, and this supplied developer is separated from the suction roll 400. To the second region 1302a formed between the two. The second area 1302a corresponds to an example of the facing area according to the present invention.

  FIG. 5 is a view showing a state of irradiation of laser exposure light from a laser exposure device.

  FIG. 5 shows a state in which the irradiation range of the laser exposure light from the laser exposure device 12 is limited to the photosensitive member 10 and does not reach the suction roll 400.

  Moreover, the electric potential which each has in the photoreceptor 10, the adsorption | suction roll 400, the image development roll 133, and the conveyance roll 134 shown by FIG. 5 is described. Although the potential of the photosensitive member 10 is set to −720 V by charging with the charging roll 11, the potential of the latent image portion formed by irradiation of laser exposure light corresponding to the image signal from the laser exposure device 12 is − 300V. On the other hand, the potential of the portion not irradiated with the laser exposure light remains -720V. Further, the suction roll 400 is set to −720 V by charging by the charging device 500 and the potential thereof is maintained. Further, the potential of the developing roll 133 is set to −600 V by a charging device (not shown), and the potential of the transport roll 134 is set to −1500 V by a power source 135 connected to the transport roll 134. The power source 135 corresponds to an example of the large difference generation potential applying unit according to the present invention.

  Due to the above potential relationship, the toner that electrostatically adheres to the magnetic carrier held on the developing roll 133 and is transported to the developing region 1301a formed between the photosensitive member 10 is contained in the developer as described above. Since the tank 132 is charged with a negative polarity, the latent image portion (potential is −300 V) generated between the latent image portion of the photoconductor 10 and the developing roller 133 (potential is −600 V). By the electric field in the direction (potential difference is 300 V), it overcomes the electrostatic attractive force with the magnetic carrier and flies to the latent image side, and the latent image is developed with toner. Thereafter, the magnetic carrier remains in a state of being attracted by the magnetic force to the surface of the cylindrical member 1331 of the developing roll 133 and is collected into the developer containing tank 132.

  Further, the overcharged toner among the toners electrostatically attached to the magnetic carrier held on the transport roll 134 and transported to the facing region 1302 a formed between the transport roll 134 and the suction roll 400 is separated from the suction roll 400. While being in the same direction as the electric field between the latent image portion of the photoconductor 10 and the developing roll 133, which is generated in the direction from the suction roll 400 (potential is −720 V) to the transport roll 134 (potential is −1500 V). By an electric field (potential difference is 780 V) stronger than the electric field between the latent image portion and the developing roll 133, the electrostatic attraction between the magnetic carrier and the magnetic roll is overcome and the suction roll 400 is attracted. As shown in FIG. 3B, the suction roller 400 is not provided with the transfer device 14 for transferring the toner image to the recording medium, and the toner sucked on the suction roller 400 remains untransferred. It reaches the cleaning device 50 and is removed from the suction roll 400 by the cleaning member 51 and stored in the residue storage box 52.

  In the printer 1, the overcharged toner that is the deteriorated toner is removed before the most upstream position P1 in the second storage chamber 132b of the developer storage tank 132, so that rapid charge transfer to the new toner is performed. Effectively suppressed, generation of low-charged toner and reverse polarity toner is suppressed.

  As described above, in the printer 1, the generation of the low-charge toner and the reverse polarity toner is suppressed by the synergistic effect of the new toner supply position control and the removal of the deteriorated toner. Further, even when a low-temperature fixing toner that is easily deteriorated as in the present embodiment is employed, the occurrence of low-charge toner and reverse-polar toner is sufficiently suppressed.

  Next, a second embodiment of the image forming apparatus of the present invention will be described.

  The difference between the image forming apparatus according to the second embodiment and the image forming apparatus according to the first embodiment is that the deteriorated toner attracted by the suction roll 400 is not an overcharged toner as in the first embodiment but is deteriorated. In addition to the slow rise in charge amount, the newly supplied toner is depleted in charge and has a low charge amount while the charge amount remains low, and is a reverse polarity toner that has been reversed due to sudden charge transfer. In addition, the potential of the transport roll 134 is a potential suitable for adsorption of the low-charge toner and the reverse polarity toner. Hereinafter, these points will be described.

  FIG. 6 is a diagram illustrating a potential relationship of the developing unit of the printer according to the second embodiment.

  FIG. 6 shows a first power source 137 having a potential of −1000 V, a second power source 138 having a potential of −500 V, and a changeover switch 136 that connects one of these to the transport roll 134 so as to be switchable. Here, a state in which the first power source 137 having a potential of −1000 V is connected to the transport roll 134 is shown.

  Of the toner that electrostatically adheres to the magnetic carrier held on the transport roll 134 and is transported to an area formed between the transport roll 134 and the toner that has been charged, The latent image is generated in the same direction as the electric field between the latent image portion of the photoreceptor 10 and the developing roll 133 from the suction roll 400 (potential is −720 V) to the transport roll 134 (potential is −1000 V). By an electric field weaker than the electric field between the portion and the developing roll 133 (potential difference is 280 V), the electrostatic attraction between the magnetic carrier and the magnetic carrier is overcome, and the suction roll 400 is attracted. Thereafter, the lowly charged toner is removed from the suction roll 400 by the cleaning member 51 of the cleaning device 50 and stored in the residue storage box 52.

  On the other hand, when the second power source 138 is connected to the transport roll 134 by the changeover switch 136, the potential of the transport roll 134 becomes −500 V, and is electrostatically attached to the magnetic carrier held by the transport roll 134, and the suction roll The reversely charged toner among the toners conveyed to the area formed between 400 and 400 is generated between the conveying roll 134 (potential is −500 V) and the adsorbing roll 400 (potential is −720 V). Due to the electric field opposite to the direction of the electric field between the latent image portion of the photoconductor 10 and the developing roll 133, the electrostatic attraction between the magnetic carrier and the magnetic carrier is overcome and attracted to the attracting roll 400. Thereafter, the reversely charged toner is removed by the cleaning member 51 of the cleaning device 50 and stored in the residue storage box 52.

  As described above, in the printer of the second embodiment, among the deteriorated toners stored in the developer storage tank 132, both the low-charge toner and the reverse polarity toner switch the potential applied to the suction roll 400. Is removed. That is, in this printer, both the low-charged toner and the reverse polarity toner that have already been generated in the developer storage tank 132 are removed. The first power source 137 corresponds to an example of the small difference generation potential applying unit according to the present invention, and the second power source 138 corresponds to an example of the reverse electric field generation potential applying unit according to the present invention. In addition, the first power source 137, the second power source 138, and the changeover switch 136 constitute an example of a potential applying unit according to the present invention. The potentials of the suction roll 400, the photoconductor 10, and the developing roll 133 other than the transport roll 134 are the same as the potentials in the printer 1 of the first embodiment, and a description thereof will be omitted.

  Next, a third embodiment of the image forming apparatus of the present invention will be described.

  The difference between the printer of the third embodiment and the printer of the second embodiment is that the exposure light irradiation range of the laser exposure device 12 extends to the center of the suction roll 400 in addition to the photosensitive member 10. In the second embodiment, the low-charged toner and the reverse-charged toner are adsorbed to the suction roll 400 by switching and applying two potentials to the transport roll 134, whereas in the third embodiment, the transport roll 134 is used. The difference is that both the low-charged toner and the reverse-charged toner are simultaneously adsorbed to the adsorbing roll 400 without switching the potential applied to.

  FIG. 7 is a diagram showing an irradiation range of laser exposure light from a laser exposure device.

  FIG. 7 shows that the irradiation object of the laser exposure light from the laser exposure device 12 extends from the photosensitive member 10 and the end of the suction roll 400 on the photosensitive member 10 side to the central portion. .

  In FIG. 7, the electric potentials of the photoreceptor 10, the suction roll 400, the developing roll 133, and the transport roll 134 are described. Since the respective potentials and potential relations of the photosensitive member 10 and the developing roll 133 have been described above, they will be omitted.

  Although the potential from the end on the photoconductor 10 side to the center of the suction roll 400 is initially set to −720 V by charging by the charging device 500, the potential of the portion irradiated with the laser exposure light is − 300 V, and the other half potential not irradiated with the laser exposure light is maintained at −720 V. Further, the potential of the transport roll 134 is set to −500 V by a charging device (not shown).

  In the printer of this embodiment having the above-described potential relationship, it adheres electrostatically to the magnetic carrier held by the transport roll 134 and extends from the end of the suction roll 400 on the photoconductor 10 side to the center ( Hereinafter, the low-charged toner among the toners conveyed to the region formed between the end of the suction roll 400 on the side of the photoconductor 10 and the center thereof is referred to as a laser irradiation region 401. Due to the electric field (potential difference is 200 V) from the laser irradiation area 401 (potential is −300 V) to the transport roll 134 (potential is −500 V), which is generated between the laser irradiation area 401 and the transport roll 134, the magnetic carrier and Overcoming the electrostatic attractive force between them, and being attracted to the laser irradiation region 401 of the attracting roll 400, and thereafter the cleaning member 51 of the cleaning device 50. Therefore been removed is accommodated in the residue housing box 52.

  On the other hand, it adheres electrostatically to the magnetic carrier held on the transport roll 134, and the other half from the central portion of the suction roll 400 (hereinafter, the other half from the central portion of the suction roll 400 is referred to as a laser non-irradiation region 402. Of the toner conveyed to the area formed between the non-irradiated region 402 and the conveying roll 134 from the conveying roll 134 (potential is −500 V). The electric field directed to the laser non-irradiation region 402 (potential is −720 V) overcomes the electrostatic attraction between the magnetic carriers and is attracted to the laser non-irradiation region 402, and then is cleaned by the cleaning member 51 of the cleaning device 50. It is removed and stored in the residue storage box 52.

  As described above, in the printer of this embodiment, both the low-charge toner and the reverse polarity toner that have already been generated in the developer storage tank 132 are removed.

  Next, a fourth embodiment of the image forming apparatus of the present invention will be described.

  The difference between the printer of the fourth embodiment and the printer of the third embodiment is in the structure of the toner supply device, the configuration for adsorbing the deteriorated toner, and the potential relationship, and this difference will be described below.

  FIG. 8 is a diagram illustrating details of the toner supply device provided in the printer of the fourth embodiment.

  FIG. 8 shows details of the toner supply device 3 provided in the printer of the fourth embodiment corresponding to the toner supply device 2 provided in the printer 1 of the first embodiment. In addition, the same code | symbol as the code | symbol attached | subjected to FIG. 4 is attached | subjected to the member of the same kind as the member shown by FIG.

  The toner supply device 3 shown in FIG. 8 includes a vertical main supply pipe 22 provided with a first main transfer member 221 inside, a horizontal main supply pipe 23 provided with a second main transfer member inside, and a horizontal main supply pipe 23. A first sub-supply pipe 24, a second sub-supply pipe 25, a third sub-supply pipe 26, and a fourth sub-supply pipe 27 extending from four places of the supply pipe 23 to four places of the second storage chamber 132b, respectively, are shown in FIG. In addition to the toner supply instruction, the controller 30 is provided with a control unit 30 that receives timing information of discharge start and discharge stop in the charger 11 shown in FIG.

  In the first sub supply pipe 24, a first sub transport member 341 having a structure in which spiral fins are provided around the rod for supplying the toner stored in the toner cartridge 21 to the second storage chamber 132b. And a first sub motor 342 for rotating the first sub transport member 341 is attached. A worm gear 3421 is attached to the rotation shaft of the first sub motor 342 and meshes with a gear 3411 provided at the rod end of the first sub transport member 341. Further, the drive of the first sub motor 342 is controlled by the control unit 30. For this reason, when the first sub motor 342 rotates according to the rotation instruction from the control unit 30, the first sub transport member 341 also rotates, and the toner contained in the toner cartridge 21 passes through the first sub supply pipe 24 to the second. It is supplied to the storage chamber 132b.

  In each of the second sub supply pipe 25, the third sub supply pipe 26, and the fourth sub supply pipe 27, a second sub transport member 351, a third sub transport member 361, and a fourth sub transport member 371 are provided. Each of the second sub supply pipe 25, the third sub supply pipe 26, and the fourth sub supply pipe 27 is provided with a second sub motor 352, a third sub motor 362, and a fourth sub motor 372, respectively. It has been. Further, the rod ends 3511, 3611, 3711 of the second sub-transport member 351, the third sub-transport member 361, and the fourth sub-transport member 371, the second sub motor 352, the third sub motor 362, and the fourth sub Worm gears 3521, 3621, and 3721 respectively attached to the rotation shaft of the motor 372 are engaged with each other. The second sub motor 352, the third sub motor 362, and the fourth sub motor 372 are also controlled by the control unit 30. Therefore, when the second sub motor 352, the third sub motor 362, and the fourth sub motor 372 are rotated by a rotation instruction from the control unit 30, the second sub transport member 351, the third sub transport member 361, Each of the four sub-transport members 371 also rotates, and the toner stored in the toner cartridge 21 enters the second storage chamber 132b via the second sub-supply pipe 25, the third sub-supply pipe 26, and the fourth sub-supply pipe 27. Supplied.

  Here, in the printer of the fourth embodiment, unlike the printer 1 of the first embodiment, from the toner supply start instruction to the toner supply stop instruction transmitted from the central control unit 100 to the control unit 30 of the toner supply device 3. The time interval is not constant, and this time interval changes according to the image density of the formed image.

  The control unit 30 measures the time interval from the toner supply start instruction to the toner supply stop instruction from the central control unit 100 and the time interval from the discharge start to the discharge stop in the charger 11 shown in FIG. Each of them is recorded in a memory (not shown) five times from the latest.

  In this control unit 30, every time a toner supply start instruction is received from the central control unit 100, five time intervals from the toner supply start instruction to the toner supply stop instruction and a time interval from the discharge start to the discharge stop are displayed. Are read from the memory and totaled. Next, the control unit 30 divides the total of the five time intervals from the toner supply start instruction to the toner supply stop instruction by the total of the five time intervals from the discharge start to the discharge stop, thereby forming an image. The toner supply time per unit time at the time is calculated. Thus, the control unit 30 measures the time interval from the start of discharge to the stop of discharge because the time interval is considered to represent the actual time during which an image is formed. is there. The calculated toner supply time per unit time becomes longer because the toner is required as the image density of the formed image is increased, and the toner is required as the image density of the formed image is decreased. Not to be shortened.

  Further, the control unit 30 determines which of the four numerical ranges (E, F, G, H) divided by the three boundary values belongs to the supply time per unit time.

  When it is determined that the toner supply time per unit time belongs to the numerical range E having the largest value among these four numerical ranges, the toner supply time per unit time is long and the density is high. Image formation is being performed. Accordingly, since the toner consumption is large, it is considered that the new toner supplied to the developer storage tank 132 is used for image formation without much stirring and transport in the developer storage tank 132. Therefore, in such a case, there is no fear that the toner deteriorates due to too many opportunities for friction with the magnetic carrier. Therefore, new toner is supplied to the most upstream position in the transport direction of the developer transported through the second storage chamber 132b of the developer storage tank 132. In such supply, after the control unit 30 receives a toner supply start instruction from the central control unit 100, the first main motor 222 and the second main motor 232 are rotated to rotate the first main transport member 221 and the second main transport member 221. This is realized by driving the main transport member 231 and rotating the first sub motor 342 that drives the first sub transport member 341 of the first sub supply pipe 24. In this way, the toner is supplied to the most upstream position, thereby avoiding a shortage of charging amount due to too few friction opportunities.

  On the other hand, when it is determined that the toner supply time per unit time belongs to the numerical range H having the smallest value among the above four numerical ranges, the toner supply time per unit time is short. That is, low-density image formation is performed. Therefore, since the amount of toner consumption is small, it is considered that it takes time until new developer is supplied to the developer storage tank 132 and used for image formation. Therefore, in such a case, in order to avoid toner deterioration due to excessive friction with the magnetic carrier, new toner is transferred to the second storage chamber 132b of the developer storage tank 132. To the most downstream position in the transport direction. In such supply, the control unit 30 rotates the first main motor 222 and the second main motor 232 and rotates the fourth sub motor 372 that drives the fourth sub transport member 371 of the fourth sub supply pipe 27. It is realized by letting. In this way, even if the toner is supplied to the most downstream position, it takes time from the supply to the use, so that a shortage of charging due to too few frictional opportunities is avoided.

  In addition, when it is determined that the toner supply time per unit time belongs to the numerical value range F of the above four numerical ranges, the control unit 30 determines whether the first main motor 222 and the second main motor 232 The second sub motor 352 that drives the second sub transport member 351 of the second sub supply pipe 25 is rotated, and the toner supply time per unit time is a numerical range G of the above four numerical ranges. If it is determined that the first sub motor 232 and the second main motor 232 are rotated, the third sub motor 362 that drives the third sub transport member 361 of the third sub supply pipe 26 is rotated. By such motor drive control, supply to the supply position according to the toner supply time per hour is realized.

  As described above, in the printer of the fourth embodiment, in order to avoid excessive friction with the magnetic carrier as the toner supply time per unit time is shorter, that is, as the image density is lower, The toner is supplied to the downstream side in the developer conveying direction at 132b. On the other hand, the longer the toner supply time per unit time, that is, the higher the image density, the more upstream in the transport direction of the developer in the second storage chamber 132b, in order to eliminate the shortage of friction with the magnetic carrier. Toner is supplied. Here, the sub-transport members 341, 351, 361, and 341 correspond to an example of the transport mechanism according to the present invention.

  FIG. 9 is a diagram illustrating a state of voltage application to the transport roll and the development roll provided in the printer of the fourth embodiment.

  FIG. 9 shows a developer holding roll 233 in which the developing roll 133 and the transport roll 134, which are separate bodies in the third embodiment, are shown. The photoconductor 10, the adsorption roll 400, and the developer holding are shown in FIG. In the roll 233, the electric potential of each is described. Since the potential relationship between the photoconductor 10 and the developer holding roll 233 has been described above, a description thereof will be omitted. Further, regarding the potentials of the laser irradiation region 401 and the laser non-irradiation region 402 on the suction roll 400, the potential of the laser irradiation region 401 was changed from -300V to -350V in the third embodiment. The explanation is omitted because there is no functional change.

  Low-charged toner out of the toner conveyed to the area formed between the laser irradiation area 401 is generated between the laser irradiation area 401 and the developer holding roll 233. 350V) to the developer holding roll 233 (potential is -600V), the electrostatic attraction with the magnetic carrier is overcome by an electric field (potential difference is 250V), and is attracted to the laser irradiation region 401, and then cleaned. It is removed by the cleaning member 51 of the apparatus 50 and stored in the residue storage box 52.

  On the other hand, the reverse polarity toner out of the toner transported to the area formed between the laser non-irradiation area 402 is generated between the laser non-irradiation area 402 and the developer holding roll 233. The electric field directed from 233 (potential is −600 V) to the laser non-irradiated region 402 (potential is −720 V) overcomes the electrostatic attraction between the magnetic carriers and is attracted to the laser non-irradiated region 402, and then It is removed by the cleaning member 51 of the cleaning device 50 and stored in the residue storage box 52.

  As described above, also in the printer of this embodiment, both the low-charged toner and the reverse polarity toner that have already been generated in the developer storage tank 132 are removed simultaneously.

  Finally, a fifth embodiment of the image forming apparatus of the present invention will be described.

  The difference between the printer of the fifth embodiment and the printer 1 of the first embodiment lies in the structure of the toner supply device, and this difference will be described below.

  FIG. 10 is a diagram illustrating details of the toner supply device provided in the printer of the fifth embodiment.

  The toner supply device 4 shown in FIG. 10 includes a main supply pipe 42 to which the toner cartridge 21 is attached and detached, a first sub supply pipe 43 extending from the main supply pipe 42 to various locations in the second storage chamber 132b, In addition to the toner supply instruction from the second sub supply pipe 44, the third sub supply pipe 45, the fourth sub supply pipe 46, and the central control unit 100 shown in FIG. And a control unit 40 for receiving image density information of the latent image to be generated.

  Each of the first sub supply pipe 43, the second sub supply pipe 44, the third sub supply pipe 45, and the fourth sub supply pipe 46 has a structure in which a spiral fin is provided around the rod. A first sub transport member 431, a second sub transport member 441, a third sub transport member 451, and a fourth sub transport member 461 are incorporated. The first sub supply pipe 43, the second sub supply pipe 44, the third sub supply pipe 45, and the fourth sub supply pipe 46 include a first sub motor 432, a second sub motor 442, and a third sub supply pipe 46, respectively. A motor 452 and a fourth sub motor 462 are attached. The rod end 4311 of the first sub-transport member 431 and the worm gear 4321 attached to the rotation shaft of the first sub-motor 432 are engaged with each other, and the second sub-transport member 441, the third sub-transport member 451, and the fourth sub-member The rod ends of the transport members 461 are connected to the rotation shafts of the second sub motor 442, the third sub motor 452, and the fourth sub motor 462, respectively. Here, the sub transport members 431, 441, 451, and 461 correspond to an example of the transport mechanism according to the present invention.

  The control unit 40 of the toner supply device 4 records the image density of five images received from the central control unit 100 and traced back from the latest in a memory (not shown). Further, when receiving the toner supply start instruction from the central control unit 100, the control unit 40 calculates an average value of the image densities for these five images, and the average image density is divided by three boundary values. It is determined which of the four numerical ranges (I, J, K, L) belongs.

  When it is determined that the average image density belongs to the numerical value range I having the largest numerical value among these four numerical value ranges, image formation with a high density is being performed. Accordingly, since the amount of toner consumed is large, it is considered that the new toner supplied to the developer storage tank 132 is used for image formation without much agitation and conveyance in the developer storage tank 132. Therefore, in such a case, there is no fear that the toner deteriorates due to too many opportunities for friction with the magnetic carrier. Therefore, new toner is supplied to the most upstream position in the transport direction of the developer transported through the second storage chamber 132b of the developer storage tank 132. In such supply, after the control unit 40 receives a toner supply start instruction from the central control unit 100, the first sub motor 432 is driven to drive the first sub transport member 431 of the first sub supply pipe 43. Realized by rotating. In this way, the toner is supplied to the most upstream position, thereby avoiding a shortage of charging amount due to too few friction opportunities.

  On the other hand, when it is determined that the average image density belongs to the numerical value range L having the smallest numerical value among the above four numerical value ranges, image formation with a low density is performed. Therefore, since the amount of toner consumption is small, it is considered that it takes time until new developer is supplied to the developer storage tank 132 and used for image formation. Therefore, in such a case, in order to avoid toner deterioration due to excessive friction with the magnetic carrier, new toner is transferred to the second storage chamber 132b of the developer storage tank 132. To the most downstream position in the transport direction. Such supply is realized by the control unit 40 rotating the fourth sub motor 462 to drive the fourth sub transport member 461 of the fourth sub supply pipe 46. In this way, even if the toner is supplied to the most downstream position, it takes time from supply to use, so the fear of insufficient charge due to too few friction opportunities is reduced.

  Further, when it is determined that the average image density belongs to the numerical value range J of the above four numerical ranges, the control unit 40 drives the second sub transport member 441 of the second sub supply pipe 44. When the second sub-motor 442 is rotated and the average image density is determined to belong to the numerical range K of the above four numerical ranges, the control unit 40 performs the third sub-transport of the third sub-supply pipe 45. The third sub motor 452 that drives the member 451 is rotated. By such motor control, supply to the supply position according to the toner supply frequency is realized.

  In the printer of the fifth embodiment, in order to avoid excessive friction with the magnetic carrier as the average of the image density of five images going back from the latest is lower, that is, as the image density is lower, in the second storage chamber 132b. The toner is supplied to the downstream side in the developer transport direction. On the other hand, the higher the average of the image densities of the five images going back from the most recent time, that is, the higher the image density, the greater the chance of friction with the magnetic carrier, so that the developer in the second storage chamber 132b in the transport direction. Toner is supplied upstream. As described above, in this printer as well, the generation of low-charge toner and reverse polarity toner is suppressed by controlling the new toner supply position.

  Although an example of a printer has been described above as an embodiment of the image forming apparatus, the image forming apparatus referred to in the present invention is not limited to a printer, and may be, for example, a copying machine or a facsimile.

  In the above embodiment, an example of a roll-shaped photosensitive member is shown as the image carrier referred to in the present invention. However, the image carrier referred to in the present invention is not limited to this, and may be, for example, a belt-shaped member. Good.

  In the above embodiment, an example in which the latent image forming unit according to the present invention is configured by a contact-type charger and a laser exposure device has been described. However, the latent image forming unit according to the present invention is not limited to this. For example, a non-contact type such as a scorotron may be used, or an array of a plurality of light emitting diodes may be used instead of the laser exposure device.

  In the above embodiment, as an example of the supply position changing mechanism referred to in the present invention, an example having a plurality of supply pipes extending from the toner supply unit into the supplyable range R of the second storage unit has been described. The supply position changing mechanism referred to in the present invention may be one in which one supply pipe moves to each location of the second accommodating portion.

  In the above-described embodiment, the low-temperature fixing toner is shown as an example of the toner attached to the latent image on the surface of the image carrier according to the present invention. However, the toner according to the present invention is not limited to the low-temperature fixing toner and is conventionally known. The toner may also be used.

DESCRIPTION OF SYMBOLS 1 Printer 2, 3, 4 Toner supply apparatus 10 Photoconductor 11 Charger 12 Laser exposure device 13 Developing device 100 Central control part 131 Stirring conveyance member 132 Developer storage tank 133 Developing roll 134 Conveying roll 14 Transfer roll 15 Fixing device 16 Paper Cassette 17 Paper transport device 20, 30, 40 Controller 21 Toner cartridge 22 Vertical main supply pipe 221 First main transport member 222 First main motor 23 Horizontal main supply pipe 231 Second main transport member 232 Second main motor 24, 43 First sub supply pipe 241 First on / off valve 25, 44 Second sub supply pipe 251 Second on / off valve 26, 45 Third sub supply pipe 261 Third on / off valve 27, 46 Fourth sub supply pipe 271 Fourth on / off valve 341 , 431 First sub transport member 342, 432 First sub motor 351, 441 Second sub transport member 352, 44 The second sub-motor 361,451 third auxiliary transport member 362,452 third sub motor 371,461 fourth auxiliary transport member 372,462 fourth sub motor 400 suction rolls 500 charger

Claims (15)

An image carrier on which a toner image is formed to hold the toner image;
A latent image forming unit that forms an electrostatic latent image on the surface of the image carrier;
A toner container that contains toner therein;
An independent member in which the surface potential is aligned with the image carrier in the direction in which the surface on which the latent image is formed by the latent image forming unit extends, independent of the surface potential of the image carrier;
A charger for charging the surface of the independent member;
A charged toner is attached to a latent image formed on the surface of the image carrier to form a toner image, and a developer containing the charged toner is accommodated therein;
Adjacent to both the image carrier and the independent member, and having a potential difference between the image carrier and the independent member, holding the developer on the surface and rotating the developer to hold the image A developing roll that conveys to a developing area facing the body and an opposing area facing the independent member; and the developer is accommodated in the developing roll adjacent to the developing roll and extending along the rotation axis of the developing roll. First supplying the developer to the developing roll and transporting it in a first direction along the rotation axis from the far side from the independent member toward the independent member while stirring the contained developer. The container is provided with a moving port that is adjacent to the first container and extends alongside the first container, and at both ends, the developer moves between the container and the first container. The developer is accommodated and toner is supplied, and the developer and the toner are agitated and mixed. However, the second storage unit that transports the toner in the second direction opposite to the first direction, the toner supply unit that supplies the toner from the toner storage unit to the second storage unit, and the toner supply unit A developing device having a supply position change mechanism that is instructed to change a supply position for supplying toner to the storage unit and changes the supply position in a direction along the second direction; and A change instructing unit that instructs the supply position changing mechanism to change the supply position to the upstream side in the second direction as the supply amount increases according to the toner supply amount;
An image forming apparatus comprising:   In the developing roll, a developing unit that transports the developer to the developing region and a non-developing unit that transports the developer to the facing region are separated from each other. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided.   The independent member has a potential difference that generates an electric field between the developing roller and the independent member in the same direction as the direction of the electric field generated between the developing roller and the image carrier, and the developing roller 3. The image forming apparatus according to claim 1, wherein the image forming apparatus has a potential difference between the developing roller and a potential difference larger than a potential difference between the image holding member and the image carrier.   The independent member has a potential difference that generates an electric field between the developing roller and the independent member in the same direction as the direction of the electric field generated between the developing roller and the image carrier, and the developing roller The image forming apparatus according to claim 1, wherein the image forming apparatus has a potential difference between the developing roller and a potential difference smaller than a potential difference between the image carrier and the image carrier.   The independent member generates a potential difference between the developing roller and the developing roller that generates an electric field opposite to the direction of the electric field generated between the developing roller and the image carrier. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided in between. An exposure device that irradiates the surface of the independent member charged by the charger with exposure light to form a potential distribution on the surface;
An electric field in the same direction as the direction of the electric field generated between the developing roll and the image carrier between the developing roll and the independent member is generated between the independent member and the developing roll due to the potential distribution. A first potential difference generated between the developing roll and the image carrier, and a direction of an electric field generated between the developing roller and the image carrier. 6. The device according to claim 1, further comprising: a second potential difference that generates an electric field in a direction opposite to that between the developing roll and the independent member. 2. An image forming apparatus according to item 1. In the developing roll, a developing unit that transports the developer to the developing region and a non-developing unit that transports the developer to the facing region are separated from each other. To be granted,
By applying a potential to the non-developing portion, a potential difference between the non-developing portion and the independent member that is greater than a potential difference between the developing portion and the image holding member, and the developing portion and the image holding portion. The image forming apparatus according to claim 1, further comprising a large difference generation potential applying unit that generates an electric field having the same direction as an electric field generated between the body and the body. . In the developing roll, a developing unit that transports the developer to the developing region and a non-developing unit that transports the developer to the facing region are separated from each other. To be granted,
By applying a potential to the non-developing portion, a potential difference between the non-developing portion and the independent member is smaller than a potential difference between the developing portion and the image holding member, and the developing portion and the image holding portion. 7. The small difference generating potential applying section that generates an electric field in the same direction as the direction of the electric field generated between the body and the body is provided. 7. Image forming apparatus. In the developing roll, a developing unit that transports the developer to the developing region and a non-developing unit that transports the developer to the facing region are separated from each other. To be granted,
By applying a potential to the non-developing portion, a reverse electric field is generated between the non-developing portion and the independent member that is opposite to the direction of the electric field generated between the developing portion and the image carrier. 9. The image forming apparatus according to claim 1, further comprising an electric field generating potential applying unit. In the developing roll, a developing unit that transports the developer to the developing region and a non-developing unit that transports the developer to the facing region are separated from each other. To be granted,
By applying a first potential to the non-developing portion, a potential difference between the non-developing portion and the independent member is smaller than a potential difference between the developing portion and the image carrier, and the developing portion And a non-developing portion independently of the non-developing portion by applying a second potential to the non-developing portion. The first electric potential and the first electric potential serving as a reverse electric field generation potential applying unit that generates an electric field opposite to the direction of the electric field generated between the developing unit and the image carrier between the member and the member. The image forming apparatus according to claim 1, further comprising a potential applying unit that can be switched between two potentials.   The change instructing unit instructs to change the supply position upstream in the second direction as the image density increases in accordance with the image density of the latent image formed by the latent image forming unit. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The change instructing unit changes the supply position to the upstream side in the second direction as the frequency increases according to the frequency of the toner supply from the toner supply unit to the second storage unit. The image forming apparatus according to claim 1, wherein the image forming apparatus instructs the position changing mechanism.   The change instructing unit changes the supply position to the upstream side in the second direction as the supply time increases in accordance with a supply time for the toner supply unit to supply the toner per predetermined time. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to instruct the supply position changing mechanism. The toner supply unit has a plurality of supply paths reaching each of a plurality of locations along the second direction in the second storage unit, and each of the plurality of supply paths has the toner at each of the plurality of locations. Is to supply
The supply position changing mechanism has a plurality of switches that open and close each of the plurality of supply paths, and opens and closes the switches according to instructions,
The change instructing unit instructs the supply position changing mechanism to select a switch corresponding to the amount of toner supplied to the second storage unit among the plurality of switches as an instruction to change the supply position. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The toner supply unit is provided in each of the plurality of supply paths reaching the plurality of locations along the second direction in the second storage unit, and is provided in each of the plurality of supply paths to supply the toner. And having a plurality of transport mechanisms that transport each of the plurality of locations along the path,
The supply position changing mechanism drives a transport mechanism according to an instruction among the plurality of transport mechanisms;
The change instructing unit instructs the supply position changing mechanism to specify a conveyance mechanism corresponding to the amount of toner supplied to the second storage unit among the plurality of conveyance mechanisms as an instruction to change the supply position. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

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