JP6516330B2 - Image forming device - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus such as a printer, a fax machine, or a copying machine.

  Conventionally, in order to quickly and properly replace a toner cartridge filled with a waste toner container that contains waste toner, the replacement timing of the waste toner container of the toner cartridge is determined based on the number of replacement toner cartridges. Thus, there has been an image forming apparatus capable of prompting a user to replace a toner cartridge having a waste toner container that has reached the replacement time with a new toner cartridge (see, for example, Patent Document 1).

JP, 2010-243911, A

  However, in an image forming apparatus provided with a plurality of image forming units for forming an image using toner supplied from the toner cartridge, for example, the amount of toner used in the image forming unit located on the upstream side in the image forming direction is If the number is large, the amount of waste toner collected by reverse transfer in the image forming unit positioned downstream in the image forming direction increases, and the waste toner container becomes full. As a result, it is determined that the image forming unit has reached the end of life even if the number of revolutions of the photosensitive drum included in the image forming unit has not reached the end of life or the unused toner remains sufficiently. Had a problem.

  The present invention has been made in view of such circumstances, and an object of the present invention is to effectively utilize the remaining life of a photosensitive drum and unused toner even when the amount of waste toner by reverse transfer is increased. An image forming apparatus that can be used is provided.

In order to solve the above problems, an image forming apparatus according to the present invention includes a first storage chamber for storing unused developer, a second storage chamber for storing a waste developer, the first storage chamber, and the first storage chamber. A third storage chamber provided between the second storage chamber and spatially continuous to the first storage chamber and the second storage chamber, and provided to be movable in the third storage chamber the a partition member separating the waste developer in the unused developer and said second storage chamber, waste developer accommodating in said third accommodating chamber from the amount of the unused developer in the first accommodating chamber The expandable volume of the space is calculated, and as a result of the calculation, the volume of the second storage chamber and the second storage chamber and the amount of waste developer stored in the second storage chamber and the third storage chamber calculation unit for calculating a waste developer storage ratio in the third accommodating chamber , When the waste developer empty space based on the waste developer storage ratio is below a predetermined threshold value, it is characterized by comprising a developer discarding means for discarding the unused developer.

  According to the present invention, it is possible to provide an image forming apparatus capable of effectively using the remaining life of the photosensitive drum and unused toner even when the amount of waste toner due to reverse transfer increases.

FIG. 1 is a schematic diagram illustrating the configuration of a printer according to an embodiment of the present invention. FIG. 2 is a schematic configuration view illustrating a configuration of an image forming unit 10 according to the present embodiment. FIG. 2 is an internal transparent perspective view of the image forming unit 10; FIG. 2 is a block diagram illustrating a control configuration of the printer 100. FIG. 5 is a diagram showing a state of an initial stage of waste toner accumulation. FIG. 6 is a diagram for explaining a state of middle stage of waste toner accumulation. FIG. 6 is a view for explaining a state in which a waste toner storage space is filled with waste toner. It is a figure explaining the concept of waste toner accommodation possible volume (W_life). It is a control graph of the environmental field which took humidity [% RH] on the vertical axis, and temperature [° C] on the horizontal axis. FIG. 6 is a flowchart illustrating a process of calculating a waste toner empty space. FIG. It is a graph showing the evaluation result of this embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following description, It can change suitably in the range which does not deviate from the summary of this invention.

  FIG. 1 is a schematic view illustrating the configuration of a printer 100 as an image forming apparatus according to the present embodiment. The printer 100 is an intermediate transfer type image forming apparatus capable of forming an image on a roll paper P as a recording medium using toner as a developer by an electrophotographic method.

  As shown in FIG. 1, an image forming unit that forms an image using toners of five colors of yellow (Y), magenta (M), cyan (C), black (K), and white (W) as the printer 100 The image forming units 10Y, 10M, 10C, 10K, and 10W are configured to be detachable from the printer 100. The image forming units 10Y, 10M, 10C, 10K, and 10W are provided. The image forming units 10Y, 10M, 10C, 10K, and 10W are sequentially arranged in one line from the upstream side to the downstream side in the image forming direction on the left side in FIG. The image forming units 10Y, 10M, 10C, 10K, and 10W have the same configuration except for the toner contained therein, and may be simply referred to as the image forming unit 10 in the following description.

  The printer 100 further includes a roll paper feeder 11 for loading and holding the roll paper P, a rewinder 12 for winding the roll paper P after image formation, and a cutter 13 for cutting the roll paper P. . The roll paper P supplied by the roll paper feeder 11 rotating in the direction of the arrow (a) in FIG. 1 is conveyed inside the printer 100 in the direction of the arrow (b) in FIG. The intermediate transfer belt 14 as a transfer material for holding and transporting the toner image (developer image) developed with each toner in the image forming unit 10 is in contact with the transport path of the roll paper P, and the toner image is A secondary transfer roller 16 to be transferred to P and a fixing device 17 to fix the toner image transferred to the roll paper P are provided. The roll paper P having passed through the fixing device 17 is taken up by the rewinder 12 rotating in the direction of the arrow (c) in FIG. In the present embodiment, the roll paper P has a width of 105 mm.

  The intermediate transfer belt 14 is an endless belt member stretched by a secondary transfer backup roller 45 and a stretching member (not shown), and in FIG. 1 with the toner image developed in the image forming unit 10 being carried. The toner image is driven to a secondary transfer point formed between the secondary transfer roller 16 and the secondary transfer backup roller 45 by driving in the direction of arrow (d). The secondary transfer roller 16 nips the conveyed roll paper P together with the toner image primarily transferred onto the intermediate transfer belt 14, and performs an intermediate operation based on a predetermined bias voltage applied from a transfer roller power source 35 described later. The toner image on the transfer belt 14 is secondarily transferred onto the roll paper P.

  Note that the image forming units 10Y, 10M, 10C, 10K, and 10W are provided at positions facing the photosensitive drums included in the image forming units 10Y, 10M, 10C, 10K, and 10W described later via the intermediate transfer belt 14. A primary transfer roller 15 (15Y, 15M, 15C, 15K, 15W) for primary transfer of the developed toner image onto the intermediate transfer belt 14 is provided. The primary transfer roller 15 (15Y, 15M, 15C, 15K, 15W) has a structure in which a metal shaft is covered with a urethane sponge layer, and based on a predetermined bias voltage applied from a transfer roller power source 35 described later. The toner image developed on the surface of the photosensitive drum is primarily transferred onto the intermediate transfer belt 14.

  The fixing device 17 includes a heating roller 17a and a pressure roller 17b, and fixes the toner image transferred to the roll paper P. The heating roller 17a is, for example, coating a heat-resistant elastic layer of silicone rubber on a hollow cylindrical metal shaft made of aluminum or the like, and coating a PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) tube thereon. It is formed by In the metal shaft, for example, a heater such as a halogen lamp (not shown) is provided. The pressure roller 17b is, for example, a metal shaft made of aluminum or the like coated with a heat-resistant elastic layer of silicone rubber and coated thereon with PFA, and a pressure contact portion is formed between the pressure roller 17b and the heating roller 17a. Are located in The roll paper P to which the toner image is transferred at the secondary transfer point is given heat and pressure when passing through a pressure contact portion formed by the heating roller 17a and the pressure roller 17b maintained at a predetermined temperature. The toner melts and the toner image is fixed.

  Further, on the intermediate transfer belt 14, a belt cleaning member 48 for scraping off the toner remaining on the intermediate transfer belt 14 after the toner image transfer by the secondary transfer roller 16 and the toner scraped off by the belt cleaning member 48 are And a belt waste toner storage portion 49 for storing.

  Next, the image forming units 10Y, 10M, 10C, 10K, and 10W will be described. As described above, since the image forming units 10Y, 10M, 10C, 10K, and 10W have the same configuration except for the toner contained therein, they will be described as the image forming unit 10 in brief.

  FIG. 2 is a schematic configuration view for explaining the configuration of the image forming unit 10. The image forming unit 10 contributes to the development of the electrostatic latent image formed on the surface of the photosensitive drum, and a developing unit 10a also serving as a developer discarding unit, an unused toner storage chamber for storing unused toner T, etc. The toner cartridge 10 b is configured to be attachable to and detachable from the developing unit 10 a.

  The developing unit 10a is rotatably supported in the direction of the arrow (e) in FIG. 2, and is formed on the photosensitive drum 19 as a cylindrical electrostatic latent image bearing member and on the upstream side of the photosensitive drum 19 in the rotational direction. The charging roller 20 as a charging device is disposed so as to be in pressure contact with the photosensitive drum 19 and rotatably supported in the direction of the arrow (f) in FIG. 2, and disposed so as to face the photosensitive drum 19. The developing roller 21 as a developer bearing member rotatably supported in the direction of the arrow (g) in FIG. 2 and the edge portion of the developing roller 21 supported on the inner wall of the toner hopper 27 are arranged to abut The developing blade 22 as a developer layer thickness regulating member, and the supplying roller 23 as a developer supplying member disposed opposite to the developing roller 21 and rotatably supported in the direction of the arrow (h) in FIG. And the photoreceptor A cleaning member 24 disposed in contact with a predetermined position on the surface of the drum 19, a charge removing device 25 disposed in non-contact with the surface of the photosensitive drum 19, and the toner cartridge 10b through the toner supply port 26. And a toner hopper 27 for temporarily storing the toner T supplied from the unused toner storage chamber 47.

  The photosensitive drum 19 is composed of a conductive support and a photoconductive layer, and is an organic photosensitive member in which a charge generation layer and a charge transport layer as a photoconductive layer are sequentially laminated on a metal shaft such as aluminum as a conductive support. The irradiation light irradiated from the exposure head 28 provided immediately above forms an electrostatic latent image based on the image data. The photosensitive drum 19 is provided with a drive gear (not shown) so as to be rotatable in the direction of the arrow (e) in FIG. 2 by a motor driving force obtained from a drive motor control unit 43 described later.

  The exposure head 28 has, for example, an LED head composed of an LED (Light Emitting Diode) element and a lens array, and the irradiation light emitted from the LED element based on head light emission command data of the photosensitive drum 19. It is arrange | positioned so that it may become a position which forms an image on the surface.

  The charging roller 20 is configured, for example, by coating a semiconductive epichlorohydrin rubber on the outer periphery of a metal shaft such as stainless steel. The charging roller 20 is disposed to be in pressure contact with the photosensitive drum 19, and uniformly and uniformly charges the surface of the photosensitive drum 19 by a predetermined bias voltage applied from a charging roller power source 36 described later. . The charging roller 20 is provided with a driving gear (not shown) so as to be rotatable in the direction of arrow (f) in FIG. 2 as the photosensitive drum 19 rotates. The charge cleaning roller 29 is provided on the charge roller 20 in pressure contact. The charging cleaning roller 29 is rotated in accordance with the rotation of the charging roller 20 according to the following rotation or difference in peripheral speed, and scrapes off the toner T and the external additive of the toner T adhering to the charging roller 20.

  For example, the developing roller 21 is coated with urethane rubber in which carbon black is dispersed on the outer periphery of a metal shaft such as stainless steel, and the surface thereof is subjected to an isocyanate treatment. The developing roller 21 is disposed so as to be in pressure contact with the surface of the photosensitive drum 19, and electrostatic latent formed on the surface of the photosensitive drum 19 by a predetermined bias voltage applied from a power source 37 for developing roller described later. By attaching toner T to the image, a toner image is developed. The developing roller 21 is provided with a driving gear (not shown) so as to be rotatable in the direction of the arrow (g) in FIG.

  The developing blade 22 is a stainless steel developer layer thickness regulating member having a thickness of, for example, about 0.08 mm and disposed so as to press in a counter direction at a predetermined position on the surface of the developing roller 21. The developing blade 22 regulates the layer thickness of the toner T by the pressing force against the surface of the developing roller 21 and forms a thin toner layer on the surface of the developing roller 21. A predetermined bias voltage is applied to the developing blade 22 from a supply roller power supply 38 described later.

  The supply roller 23 is configured, for example, by coating a semiconductive foamed silicone sponge layer on the outer periphery of a metal shaft such as stainless steel. The supply roller 23 is disposed so as to be in pressure contact with the developing roller 21, and the developing roller is provided with the toner T temporarily stored in the toner hopper 27 by a predetermined bias voltage applied from a supply roller power source 38 described later. Supply to 21 The supply roller 23 is provided with a drive gear (not shown) so as to be rotatable in the direction of arrow (h) in FIG.

  The cleaning member 24 is made of, for example, urethane rubber, and one end thereof is disposed in contact with a predetermined position on the surface of the photosensitive drum 19. The cleaning member 24 cleans the surface of the photosensitive drum 19 by scraping off the toner T remaining on the surface of the photosensitive drum 19. The first waste toner conveyance member 50 is provided immediately below the cleaning member 24. The first waste toner conveying member 50 conveys the toner T removed from the surface of the photosensitive drum 19 by the cleaning member 24 as a waste toner T ′ toward a waste toner storage chamber 54 of a toner cartridge 10 b described later.

  The charge removing device 25 is disposed in non-contact with the surface of the photosensitive drum 19 and removes the residual charge on the surface of the photosensitive drum 19. The static elimination device 25 can be configured by, for example, a light emitting element such as an LED.

  The toner cartridge 10 b includes an unused toner storage chamber 47 as a first storage chamber for storing unused toner T, and a second storage for storing waste toner T ′ removed from the surface of the photosensitive drum 19 by the cleaning member 24. A waste toner chamber 54 as a chamber, and a movable partition chamber 55 as a third storage chamber configured so that the partition member 52 is deformed and movable.

  The partition member 52 is made of an LDPE (Low Density Polyethylene) film having a thickness of 0.1 mm to 0.4 mm, and can be deformed in the movable partition chamber 55. The partition member 52 is disposed between the unused toner storage chamber 47 and the waste toner chamber 54, and the end of the partition member 52 is the toner cartridge 10b so that the unused toner T and the waste toner T 'are not mixed. It is fixed to the case. Further, as shown in FIG. 2, when the image forming unit 10 is not in use, the partition member 52 is provided along the side wall on the waste toner chamber 54 side, and the unused toner T is used as the unused toner chamber 47. It is accommodated in the movable partition chamber 55.

  The toner T according to this exemplary embodiment is configured of a binder resin and a charge control agent as an internal additive, a release agent, a colorant, or an external additive. The binder resin and the internal additive are kneaded using, for example, a Henschel mixer, then melt-kneaded using a twin screw extruder, cooled, and roughly crushed using a cutter mill, and then using a collision plate crusher The toner base particles can be obtained by pulverizing and further performing classification using an air classifier. An external additive, for example, an inorganic fine powder such as hydrophobic silica is added to the toner base particles, and stirring is performed for a predetermined time to obtain the target toner T of black, magenta, cyan, yellow or white. it can.

  The second waste toner transport member 51 transports the waste toner T ′ removed from the surface of the photosensitive drum 19 by the cleaning member 24 and transported by the first waste toner transport member 50 into the waste toner chamber 54.

  FIG. 3 is an internal transparent perspective view of the image forming unit 10. As described above, the first waste toner conveying member 50 provided immediately below the cleaning member 24 is a coil spiral that rotates at a constant circumferential speed in a predetermined rotational direction by a driving force obtained from a driving unit (not shown). is there. The waste toner T ′ is transported in the direction of arrow (i) in FIG. 3 as the first waste toner transport member 50 rotates. Similarly, the second waste toner conveying member 51 provided in the waste toner chamber 54 is a coil spiral that rotates at a constant circumferential speed in a predetermined rotation direction by a driving force obtained from a driving unit (not shown). The waste toner T ′ is transported in the direction of arrow (j) in FIG. 3 as the second waste toner transport member 51 rotates. The end 50 a of the first waste toner conveyance member 50 and the end 51 a of the second waste toner conveyance member 51 are connected by a waste toner conveyance path member 56 installed inside the side plate 53.

  FIG. 4 is a block diagram for explaining the control configuration of the printer 100 according to the present embodiment. The printer 100 receives image data from an external device such as, for example, a PC (Personal Computer), which controls the overall printing operation in an integrated manner, and generates image data for emitting head light to the exposure head 28. A conversion unit 31, a drum rotation number side 32 for measuring the number of rotations of the photosensitive drum 19, and a head light emission number measurement side 33 for measuring the number of light emission of light emitting elements corresponding to image data in the exposure head 28; A print data monitoring unit 34 for monitoring a page change in print data, a transfer roller power source 35 for applying a predetermined bias voltage to the primary transfer roller 15 and the secondary transfer roller 16, and a predetermined bias voltage for the charging roller 20 , A developing roller power supply 37 for applying a predetermined bias voltage to the developing roller 21, and a supply roller 23. Power supply 38 for applying a predetermined bias voltage to the developing blade 22, a head drive control unit 39 for controlling the light emission of the exposure head 28, and a predetermined voltage for emitting light from the light emitting element provided in the static elimination device 25. A fixing control unit 41 for controlling the fixing device 17 having the heating roller 17a and the pressing roller 17b, a conveyance motor control unit 42 for controlling the operation of the roll paper feeder 11, and an intermediate transfer belt 14, a drive motor control unit 43 that controls the rotation operation of the secondary transfer roller 16 and the photosensitive drum 19, a cutter operation control unit 44 that controls the operation of the cutter 13, a calculation unit 45 that performs various calculations, and a user And a lifetime display unit 46 for notifying of the remaining amount and the lifetime of the waste toner accommodation space of the image forming unit 10.

  Next, the printing operation of the printer 100 according to the present embodiment will be described. First, when the print control unit 30 of the printer 100 receives image data from an external device such as a PC via the image data conversion unit 31, the print operation starts.

  The print control unit 30 drives the photosensitive drum 19 via the drive motor control unit 43, and rotates the photosensitive drum 19 in the direction of the arrow (e) in FIG. 2 at a constant circumferential speed. The driving force by the rotation of the photosensitive drum 19 is transmitted by a driving gear (not shown), and the developing roller 21 and the supply roller 23 rotate in the direction of arrow (g) and in the direction of arrow (h) in FIG. At this time, the first waste toner conveyance member 50 and the second waste toner conveyance member 51 also rotate, and waste toner T 'generated in the process described later is shown in the arrow (i) direction and the arrow (j) direction in FIG. Transport in the direction.

  The charging roller 20 is not connected to these drive gears, and rotates in the direction of the arrow (f) in FIG. At this time, a predetermined bias voltage is applied from the charging roller power supply 36 to the charging roller 20 provided in contact with or in pressure contact with the surface of the photosensitive drum 19, so that the surface of the photosensitive drum 19 is uniformly uniform. It is charged. In the present embodiment, the aluminum base tube serving as the conductive support of the photosensitive drum 19 is grounded, and a voltage of -1000 V is applied to the charging roller 20, so that the surface of the photosensitive drum 19 has a level of about -500 V. It is charged.

  Next, as an exposure process, the exposure head 28 irradiates light corresponding to head light emission command data on the charged surface of the photosensitive drum 19 to form an electrostatic latent image on the surface of the photosensitive drum 19. In the present embodiment, the potential of the surface of the exposed photosensitive drum 19 is about -50V.

  Further, the electrostatic latent image on the surface of the photosensitive drum 19 is developed by the toner T by the operation of the developing unit 10 a described later, and a toner image is formed on the upper surface of the photosensitive drum 19. In the present embodiment, a bias voltage of -200 V is applied to the developing roller 21 by the developing roller power source 37, and the potential of the toner layer thinned by the developing blade 22 becomes about -50 V. Since the sum of the potential of the toner thin layer and the voltage applied to the developing roller 21 exceeds the potential of the exposed portion of the surface of the photosensitive drum 19, the exposed portion on the surface of the photosensitive drum 19 is developed with the toner T. The total of the electric potential of the toner thin layer and the voltage applied to the developing roller 21 does not exceed the electric potential of the unexposed portion of the surface of the photosensitive drum 19, so the unexposed portion on the surface of the photosensitive drum 19 is toner T. Not developed

  Then, the print control unit 30 instructs the drive motor control unit 43 to drive the intermediate transfer belt 14. In response to the instruction, the drive motor control unit 43 drives the intermediate transfer bell path 14 in the direction of the arrow (d) in FIG. At the same time, the print control unit 30 controls the transfer roller power supply 35 to apply a bias voltage of 2000 V to the primary transfer roller 15 provided opposite to the photosensitive drum 19. The toner image formed on the surface of the photosensitive drum 19 is primarily transferred onto the intermediate transfer belt 14 by the electric field generated between the primary transfer roller 15 and the aluminum tube of the photosensitive drum 19. By driving the intermediate transfer belt 14, toner images of up to five colors of yellow, magenta, cyan, black and white are sequentially superimposed on the intermediate transfer belt 14 after passing the white image forming unit 10W. become.

  On the other hand, the print control unit 30 causes the roll paper feeder 11 to be driven through the conveyance motor control unit 42 to convey the roll paper P to the secondary transfer point. The secondary transfer roller 16 is in contact with the intermediate transfer belt 14, and the backup roller 45 is grounded. A bias voltage of 2000 V is applied to the secondary transfer roller 16 by the transfer roller power supply 35, and the electric field generated between the secondary transfer roller 16 and the backup roller 45 causes the primary transfer belt 14 to be formed on the intermediate transfer belt 14. The transferred toner image is transferred to the roll paper P.

  The roll paper P to which the toner image has been transferred is given heat and pressure by passing through the fixing device 17, and the toner image is fixed. Then, the rewinder 12 winds the roll paper P on which the toner image is fixed while rotating in the direction of the arrow (c) in FIG.

  The print data monitoring unit 34 recognizes the page change in the print data by detecting that the light emission of the exposure head 28 has ended based on the head light emission command data generated by the image data conversion unit 31. When the print data monitoring unit 34 recognizes a page change, the print control unit 30 operates the cutter 13 via the cutter movement control unit 44, so that a portion after a predetermined margin after the print end portion of the roll paper P The roll paper P is cut.

  Although a small amount of toner T may remain on the surface of the photosensitive drum 19 after the primary transfer, the residual toner T (= transfer residual toner T) is removed by the cleaning member 24. The transfer residual toner T and part of the external additive may slip through the cleaning member 24 and may be wound around the charging roller 20. These are removed by the charge cleaning roller 29.

  Then, the charge removing device 25 applies the charge removing light to the surface of the photosensitive drum 19 to remove the unexposed charge on the surface of the photosensitive drum 19. The photosensitive drum 19 from which the unexposed charge has been removed is repeatedly used by being charged again by the charging roller 20.

  Although a small amount of toner T may remain on the intermediate transfer belt 14 after the secondary transfer, this residual toner T is removed by the belt cleaning member 48. The residual toner T removed by the belt cleaning member 43 is conveyed, for example, by a waste toner conveying member (not shown) such as a spiral or a paddle, and is collected in the waste toner storage unit 49. Thus, the intermediate transfer belt 14 is repeatedly used.

  By the way, in the image forming units other than the image forming unit 10Y positioned at the most upstream position of image formation, the toner image primarily transferred by the image forming unit positioned upstream of the own image forming unit is the image forming unit When passing through the photosensitive drum 19, the phenomenon of so-called reverse transfer may occur in which a part of the toner image is transferred from the intermediate transfer belt 14 onto the surface of the photosensitive drum 19. For example, in the case of the image forming unit 10C, the yellow toner image developed by the image forming unit 10Y located on the upstream side and the magenta toner image developed by the image forming unit 10M are the photosensitive members of the image forming unit 10C. When passing through the drum 19, a part of the toner image may be reversely transferred to the surface of the photosensitive drum 19. In this manner, the toner T reversely transferred is removed as waste toner T ′ by the cleaning member 24 by the rotation of the photosensitive drum 19 in the same manner as the transfer residual toner T.

  Here, the printing operation in the developing unit 10a will be described. As described above, the developing roller 21 and the supply roller 23 obtain the rotational driving force of the photosensitive drum 19 and rotate in the direction of arrow (g) and in the direction of arrow (h) in FIG.

  The toner T stored in the toner hopper 27 is conveyed to the developing roller 21 by the rotation of the supply roller 23. Since the developing roller 21 and the supply roller 23 rotate in opposite directions at the contact portion, the toner T is negatively charged by friction. When the toner T conveyed to the developing roller 21 passes through a portion of the developing roller 21 in contact with the developing blade 22, the toner T is thinned while being frictionally charged by the developing roller 21 and the developing blade 22. In the present embodiment, a bias voltage of -300 V is applied to the supply roller 23 and the developing blade 22 by the supply roller power supply 38. The toner T thinned in this manner adheres to the electrostatic latent image formed on the surface of the photosensitive drum 19 to develop a toner image.

  Next, transition of the accumulation state of the waste toner T ′ in the toner cartridge 10 b will be described.

  FIG. 5 is a view showing the state of the initial stage of waste toner accumulation. As shown in FIG. 5, the waste toner T ′ conveyed by the second waste toner conveying member 51 is first deposited in the waste toner chamber 54.

  FIG. 6 is a view for explaining the state in the middle stage of the waste toner accumulation. As shown in FIG. 6, the unused toner T in the unused toner storage chamber 47 is used, and the partition member 52 is deformed in the direction of the arrow in FIG. The waste toner storage space inside is expanding.

  FIG. 7 is a view for explaining a state in which the waste toner storage space is filled with the waste toner T ′. As shown in FIG. 7, the partition member 52 expands the waste toner storage space by being deformed to the deformation limit in the movable partition chamber 55.

  Incidentally, the waste toner accommodation rate according to the present embodiment is obtained by the following equation 1.

  Waste toner accommodation rate [%] = volume occupied by waste toner T ′ (W) / waste toner acceptable volume (W_life) × 100 (Equation 1)

  Here, the waste toner accommodating volume (W_life) will be described. FIG. 8 is a view for explaining the concept of the waste toner storable volume (W_life) in the present embodiment. 8A shows the toner state in the image forming unit 10 shown in FIG. 2, FIG. 8B shows the toner state in the image forming unit 10 shown in FIG. 6, and FIG. The toner states in the image forming unit 10 shown in FIG. 7 are simplified and illustrated.

  The waste toner accommodating volume (W_life) according to the present embodiment represents the volume of the space which the waste toner T ′ can occupy, and FIGS. 8A, 8B, 8C. In each case, it will be described how the waste toner capacity (W_life) is calculated.

  In the following description, the volume of the waste toner chamber 54 will be described as Wa, the volume of the moving partition chamber 55 as Wb_max, and the volume of the space where the waste toner T 'can be occupied in the moving partition chamber 55 as Wb. . Furthermore, in order to give a margin to the calculation, Wa and Wb_max are set to a value of 80% of the real space volume and then used for the following calculation. Here, Wa and Wb_max are fixed values, and Wb is a variable value, and Wb takes a value between the minimum value 0 and the maximum value Wb_max.

  First, in the state shown in FIG. 8A, the unused toner T is fully filled in the unused toner chamber 47 and the movable partition chamber 55, and the waste toner T 'is in a space other than the waste toner chamber 54. Can not occupy. Therefore, W_life at this time can be obtained by the following equation 2.

  W_life = Wa (equation 2)

Next, in the state shown in FIG. 8B, since the toner T is used, the partition member 52 of the movable partition chamber 55 can be deformed in the direction of the arrow in FIG. 8B. There is. W_life at this time can be calculated by the following equation 3.
W_life = Wa + Wb (equation 3)

  In the above equation 3, Wb is equal to the amount of toner T used. The method of obtaining this Wb will be described later.

Finally, in the state shown in FIG. 8C, the toner T is sufficiently used, and the partition member 52 in the movable partition chamber 55 is deformed to the limit. W_life at this time can be calculated by the following equation 4.
W_life = Wa + Wb_max (Equation 4)

Here, how to determine Wb, which is the amount of toner T used, will be described. Wb is expressed by the sum of the amount consumed by the development accompanying the dot emission of the exposure head 28 and the amount consumed as the drum fog, and can be obtained by the following equation 5.
Wb = (consumed amount by development accompanied by dot emission + consumed amount by drum fog) × volume-based count (Vcnt) (Equation 5)

  Here, the volume reference count (Vcnt) is 0.6, which is the value of the toner volume per dot count.

Then, the number of dot emission in the case of one A6 sheet (105 mm × 148 mm) and the lighting rate (= printing rate) of dots of 5% is determined to be 198 × 8192 dots. At this time, a portion of 198 obtained by dividing the dot light emission number by 8192 is referred to as light emission dot count. If the consumption amount by development in connection with the dot light emission in Equation 5 is expressed in dot count units, Equation 6 below is obtained.
Consumption due to development with dot light emission = (198/5) × average printing rate [%] × printing distance converted to A6 number of sheets (Equation 6)

By the way, the drum fog refers to toner T having a charge amount lower than that of normally negatively charged toner T or toner in which toner T charged to the opposite polarity is attached to the unexposed portion of the photosensitive drum 19. The amount of adhesion of the drum fog varies depending on the temperature and humidity environment and the difference in color. However, if these conditions are determined, the amount of consumed toner due to the drum fog is a value proportional to the number of rotations of the photosensitive drum 19 It will be proportional to the count. Then, when the toner consumption amount due to drum fogging in Expression 5 is expressed in dot count units, Expression 7 below is obtained.
Consumption due to drum fog = fog correction coefficient D (depends on temperature and humidity environment and differences in color) x drum count (Equation 7)

  Here, one drum count is based on the distance by which the photosensitive drum 19 rotates as the printing distance advances 444 mm, and corresponds to three A6 sheets.

FIG. 9 is a control graph of the environment area in which the humidity [% RH] is taken on the vertical axis and the temperature [° C.] is taken on the horizontal axis. Table 1 shows the fog correction coefficient D for each environmental color in a table for each toner color. It is

  The reason why the value of the fog correction coefficient D for each toner color is large in the region 1 of Table 1 is because the drum fog is more frequently generated as the temperature and humidity are higher.

  From the temperature and humidity environment where the image forming unit 10 is placed, the value to be substituted into the fog correction coefficient D in Expression 7 is set as an environment area from FIG. Determine the information on the environment area and the color with reference to the table in Table 1.

Then, the volume (W) occupied by the waste toner T ′ in Equation 1 can be calculated from Equation 8 below.
Waste toner volume (W) = transfer residual toner volume (Wtr) + fog transfer residual toner volume (Wk) + reverse transfer toner volume (Wr) (Equation 8)

Further, the transfer residual toner volume (Wtr) in Equation 8 can be calculated from Equation 9 below.
Transfer residual toner volume (Wtr) = transfer residual efficiency (J) × emission dot count × volume reference count (Vcnt) (Equation 9)

  The transfer residual efficiency (J) in the equation 9 is 3% in the present embodiment. Further, as described above, the volume reference count (Vcnt) is the toner volume per dot count, and is 0.6 in the present embodiment.

By the way, the transfer residual toner volume (Wk) of fog in Equation 8 can apply the concept of efficiency similar to the case of obtaining the transfer residual toner volume (Wtr), and can be calculated from the following Equation 10 .
Transfer residual toner volume of fog (Wk) = transfer residual efficiency of fog (Q) × drum count × volume reference count (Vcnt) (Equation 10)

  The transfer residual efficiency (Q) of the fog in the equation 10 is 3% in the present embodiment.

Further, the reverse transfer toner volume (Wr) in the equation 8 can be calculated by the following equation 11.
Reverse transfer toner volume (Wr) = Σ (reverse transfer efficiency (R) × unused toner consumption amount (Wb) × volume reference count (Vcnt))
Here, the sigma sum considers all the image forming units located on the upstream side of the image forming direction except the target image forming unit. (Equation 11)

Table 2 is a table in which the reverse transfer efficiency (R) for each environment area is tabulated for each toner color.

  Here, the life of the image forming unit 10 is controlled by the amount of rotation of the photosensitive drum 19, the amount of unused toner T, and the waste toner empty space, and even one of these three exceeds the set threshold. Then, it is determined that the image forming unit 10 has reached the end of its life and is replaced. At this time, for example, when the amount of toner used in the image forming unit 10 positioned on the upstream side in the image forming direction is large, the amount of waste toner collected by reverse transfer is the image forming unit 10 positioned on the downstream side in the image forming direction. The image forming unit is determined to have reached the end of life even if the number of rotations of the photosensitive drum has not reached the end of life or the unused toner T has remained sufficiently. was there.

  The process of calculating the waste toner empty space for solving the above problem will be described with reference to the flowchart of FIG.

  First, in step S101, when the calculation process of the waste toner storage rate is started, the print control unit 30 instructs the drum rotation number side 32 to measure the number of rotations of the photosensitive drum 19. The drum rotation number side 32, which has received the instruction, measures the number of rotations of the photosensitive drum 19 (step S102).

  Next, the print control unit 30 instructs the head light emitting meter side portion 33 to measure the light emitting number of the light emitting element corresponding to the image data in the exposure head 28. The head light emitting number side portion 33 which has received the instruction measures the light emitting number of the light emitting element corresponding to the image data in the exposure head 28.

  In step S104, the print control unit 30 instructs the calculation unit 45 to calculate the usage amount of the toner T using Expression 5, Expression 6, and Expression 7. The calculation unit 45 that has received the instruction calculates the usage amount (Wb) of the toner T from the drum count and the light emission dot count.

  Next, the print control unit 30 instructs the calculation unit 45 to calculate the waste toner storable amount A, which is the waste toner storable volume (W_life) using Expression 3. The calculation unit 45 that has received the instruction calculates the waste toner storable amount A from the usage amount of the toner T (step S105).

  Subsequently, the print control unit 30 calculates the waste toner amount B, which is the waste toner volume (W) as the sum of the transfer residual toner, the fog toner, and the reverse transfer toner, using Formula 8, Formula 9, Formula 10, Formula 11. It instructs the calculation unit 45 to do this. Upon receiving the instruction, the calculation unit 45 calculates the waste toner amount B from the drum count and the light emission dot count (step S106).

  In step S <b> 107, the print control unit 30 instructs the calculation unit 45 to calculate the waste toner accommodation rate using Equation 1. The calculation unit 45 that has received the instruction calculates the waste toner accommodation rate C using the calculated waste toner storable amount A and the waste toner amount B.

Next, the print control unit 30 instructs the calculation unit 45 to calculate the waste toner empty space D using the following equation 12. The calculation unit 45 that has received the instruction calculates the waste toner empty space D using the calculated waste toner accommodation rate C (step S108).
Waste toner empty space D [%] = 100-Waste toner accommodation rate C [%] (Equation 12)

  When the waste toner empty space D is equal to or less than 20% (Y in step S109), the process proceeds to step S110. On the other hand, if the waste toner empty space D is larger than 20% (step S109 N), the print control unit 30 ends the series of processes (step S116).

  Next, the print control unit 30 confirms whether Wb_max−Wb = 0. Here, if Wb_max−Wb = 0 (step S110 Y), the print control unit 30 confirms whether the waste toner empty space D is 0 or not. Here, if the waste toner empty space D is 0 (Y in step S111), the print control unit 30 determines that the life of the image forming unit 10 due to waste toner full (full) is because the waste toner empty space is 0. Then, the life display unit 46 is instructed to display a message prompting replacement of the image forming unit 10 (step S115), the operation of the printer 100 is stopped, and a series of processing is ended (step S116).

  If Wb_max-Wb = 0 is not satisfied (step S110 N), the print control unit 30 determines whether Wb_max-Wb ≧ Z (arbitrary toner discarding amount). Here, if Wb_max-Wb ≧ Z is satisfied (Y in step S112), the print control unit 30 discards the unused toner T for Z minutes (step S113), and ends the series of processes (step S116). On the other hand, if Wb_max-Wb ≧ Z is not satisfied (step S112 N), the print control unit 30 discards the unused toner T for (Wb_max-Wb) (step S114) and ends the series of processing (step S116). . As in step S113 and step S114, when Wb_max> Wb, by consuming (discarding) unused toner, the waste toner accommodating volume (W_life) can be increased and the life of the image forming unit 10 can be extended. .

  The calculation process shown in the flowchart of FIG. 10 is executed each time five A6 sheets (= 740 mm) are printed.

  Next, the discarding operation of the toner T in the present embodiment will be described.

  When the toner discarding operation is performed, the bias voltage applied to the primary transfer roller 15, the charging roller 20, the developing roller 21, the developing blade 22, and the supply roller 23 is the same as that in the printing operation. In addition, the static elimination light by static elimination apparatus 25 is taken as whole surface exposure. The drive motor control unit 43 drives the intermediate transfer belt 14 and the photosensitive drum 19, but since the secondary transfer roller 16 is separated from the intermediate transfer belt 14 in this case, it is not driven. Furthermore, since the sheet feeding operation is not performed, the operation control of the heating roller 17 a and the pressure roller 17 b by the fixing control unit 41 and the operation of the cutter 13 by the cutter operation control unit 44 are not performed.

  The operation of discarding the toner T will be specifically described on the premise of the above operating conditions. First, an electrostatic latent image is formed on the surface of the photosensitive drum 19 by causing the exposure head 28 to emit light, and toner corresponding to the amount of waste is attached to the photosensitive drum 19 to perform development.

  The waste toner on the surface of the photosensitive drum 19 is primarily transferred onto the intermediate transfer belt 14. At this time, since the secondary transfer roller 16 is separated from the intermediate transfer belt 14, the waste toner on the intermediate transfer belt 14 is removed by the belt cleaning member 48 and collected in the waste toner storage unit 49.

  As described above, by performing the discarding operation of the toner T, it is possible to prevent the toner cartridge 10b itself from becoming unusable due to the accumulation of the waste toner T ', and preventing the toner cartridge 10b from being damaged or punctured. .

  Next, in order to confirm the effect of this embodiment, the evaluation described below was performed.

Under an environment of temperature 27 ° C. and humidity 80% RH (corresponding to area 1 shown in FIG. 9), the volume W of the waste toner chamber 54
Under the conditions of a = 238386 mm ³ and moving partition room 55 volume Wb_max = 130563 mm ³ , the average printing rate in white toner color is 2%, and the average printing rate in yellow, magenta, cyan and black toner colors is 60. %, Until the waste toner empty space of the white image forming unit 10W located at the most downstream position in the image forming direction is 0% while continuous printing is being performed, that is, until the image forming unit 10W reaches the end of life The number of printable prints was investigated.

The evaluation results are shown in FIG. In the graph of FIG. 11, the solid line indicated by (a) represents the transition of the number of printed sheets according to the present embodiment. The toner amount Z in the toner discarding implemented when the waste toner empty space of the white image forming unit 10W becomes 20% is set to 30,000 mm ³ . The dotted line shown in (b) represents, as a comparative example, the transition of the number of printed sheets when toner waste is not performed even when the empty space of the waste toner of the white image forming unit 10W becomes 20%. As shown in FIG. 11, it has been confirmed that the present embodiment in which toner disposal is performed can print about 1,200 more sheets than in the case where toner disposal is not performed.

  As described above, according to the present embodiment, an image forming apparatus capable of effectively using the remaining life of the photosensitive drum and unused toner even when the amount of waste toner due to reverse transfer increases. Can be provided.

  In the description of the present invention, an intermediate transfer type printer for printing on roll paper has been described, but the present invention is not limited to this, a direct transfer type printer for printing on cut paper, a facsimile, The present invention is also applicable to an image forming apparatus such as an MFP.

10, 10Y, 10M, 10C, 10K, 10W Image Forming Unit 10a Development Unit 10b Toner Cartridge 11 Roll Paper Feeder 12 Rewinder 13 Cutter 14 Intermediate Transfer Belts 15Y, 15M, 15C, 15K, 15W Primary Transfer Roller 16 Secondary Transfer Roller 17 fixing device 17a heating roller 17b pressure roller 19 photosensitive drum 20 charge roller 21 development roller 22 development blade 23 supply roller 24 cleaning member 25 cleaning member 25 charge removal device 26 toner replenishment port 27 toner hopper 28 exposure head 29 charge cleaning roller 30 print control section 31 image data conversion unit 32 drum rotation number side 33 head light emission number side 34 print data monitoring unit 35 transfer roller power supply 36 charging roller power supply 37 development roller power supply 38 supply roller power supply 3 Head drive control unit 40 Power supply for static elimination light 41 Fixing control unit 42 Transport motor control unit 43 Drive motor control unit 44 Cutter control unit 45 Calculation unit 46 Life indication unit 47 Unused toner storage chamber 48 Belt cleaning member 49 Waste toner storage chamber 50 First waste toner conveyance member 51 second waste toner conveyance member 52 partition member 53 side plate 54 waste toner chamber 55 moving partition chamber 56 waste toner conveyance path member

Claims (7)

A first storage chamber for storing unused developer;
A second storage chamber for storing the waste developer;
A third storage chamber provided between the first storage chamber and the second storage chamber and spatially continuous with the first storage chamber and the second storage chamber;
A partition member provided so as to be movable in the third storage chamber, and separating the unused developer in the first storage chamber and the waste developer in the second storage chamber;
The expandable volume of the waste developer storage space in the third storage chamber is calculated from the usage amount of the unused developer, and the calculation result, the volume of the second storage chamber, and the second storage chamber and the above A calculation unit that calculates a waste developer storage ratio in the second storage chamber and the third storage chamber from the amount of waste developer stored in the third storage chamber;
If the waste developer empty space based on the waste developer storage ratio is below a predetermined threshold value, the image forming apparatus characterized by comprising a developer discarding means for discarding the unused developer. The partition member operates to expand the storage volume of the waste developer based on the amount of the waste developer stored in the second storage chamber and the third storage chamber. The image forming apparatus according to 1. A rotatably supported latent image carrier,
An exposure member for forming a latent image on the latent image carrier by emitting light;
The image forming apparatus according to claim 1 or 2, wherein the calculation unit calculates the amount of use of the unused developer from the number of rotations of the latent image carrier and the number of light emissions of the exposure member. apparatus. The expandable volume of the waste developer storage space in the third storage chamber is equal to the volume conversion of the amount of unused developer used. An image forming apparatus according to claim 1. The amount of waste developer stored in the second storage chamber and the third storage chamber is the sum of the amounts of transfer residue, transfer residue of fog developer and reverse transfer. An image forming apparatus according to any one of claims 1 to 4. When the differential volume capacity obtained by subtracting the expansible volume capacity of the waste developer storage space in the third storage chamber from the storage volume capacity of the third storage chamber is equal to or greater than a predetermined volume capacity, the developer discarding means The image forming apparatus according to any one of claims 1 to 5, wherein the unused developer of the predetermined volume capacity is discarded. When there is less than a predetermined volumetric capacity of the differential volumetric capacity obtained by subtracting the expansible volumetric capacity of the waste developer accommodating space in the third accommodating chamber from the accommodating volumetric capacity of the third accommodating chamber, the developer discarding means The image forming apparatus according to any one of claims 1 to 5, wherein the unused developer of the differential volume capacity is discarded.