JP5103843B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a printer, a copying machine, a facsimile, or a multifunction machine having these functions.

JP-A-11-119531 JP 09-22237 A JP 11-119534 A

  Conventionally, as a developing device used in an image forming apparatus such as a printer, a copying machine, a facsimile, or a multifunction machine having these functions, which employs this type of electrophotographic system, one-component development consisting only of toner is used. There are those using an agent, and those using a two-component developer composed of a carrier and a toner. Among these developing devices, a developing device using a two-component developer composed of a carrier and a toner converts the electrostatic latent image formed on the photosensitive drum by a magnetic brush of the two-component developer into gradation and It can be developed with good resolution and is suitable for color image development.

  By the way, in the developing apparatus using the two-component developer composed of the carrier and the toner, it is known that the carrier in the developer is deteriorated and the development specification is lowered while the developing process is repeated.

  Therefore, in a developing device using such a two-component developer, a recovery region for recovering the developer is provided in a part of the developing device, and excess developer moved to the recovery region is supplied at a predetermined timing. A so-called “trickle” developing system that is configured to collect in a collection container has been proposed and is actually used.

  In an image forming apparatus that forms an image by developing an electrostatic latent image formed on a photosensitive drum using a developing apparatus that employs such a “trickle” developing system, excessive development in the developing apparatus is performed. It is necessary to collect the agent into the collection container at a predetermined timing, but when the collection container is filled with the collected developer, it is necessary to replace the collection container with a new one.

  Thus, as a technique for detecting the fullness of the collection container, for example, a technique disclosed in Japanese Patent Application Laid-Open No. 11-119534 has already been proposed.

The developing device according to Japanese Patent Laid- Open No. 11-119531 develops an electrostatic latent image formed on an image carrier using a developer containing toner and a carrier, and forms a toner image on the image carrier. The developing device main body, the developer supplying means for supplying the developer to the developing device main body, the deteriorated developer from the developing device main body is discharged, and the deteriorated developer is stored in the collection container. In the developing device provided with the developer recovery means, provided is a recovery amount detection means for detecting that the deteriorated developer contained in the recovery container has reached a predetermined amount, while the deteriorated developer by the recovery amount detection means After the detection, when the developer supplied from the developer supply means is determined to have reached a predetermined amount, a recovery control means for stopping the operation of the developer body is provided. Is a thing .

  Further, in the conventional image forming apparatus, the transfer residual toner remaining on the photosensitive drum or the intermediate transfer member is removed by the cleaning device, and the transfer residual toner removed by the cleaning device is collected in the waste toner collection box. It is configured.

  Also in such an image forming apparatus, when the waste toner collection box is filled with waste toner, it is necessary to replace the waste toner collection box with a new one.

  Therefore, as a technique for detecting the fullness of the waste toner collection box, for example, those disclosed in Japanese Patent Application Laid-Open Nos. 09-22237 and 11-119534 have been proposed.

  A toner recovery amount detection method for an electrophotographic apparatus according to Japanese Patent Application Laid-Open No. 9-22237 includes a developer that develops using a developer composed of toner and a carrier, a toner hopper that stores the toner, and a toner hopper to the developer. A developing mechanism that includes a toner feed driving unit that replenishes toner, a cleaning device that cleans residual toner on the photosensitive member after transferring a toner image developed on the photosensitive member from the developing device to the paper, and the cleaning In an electrophotographic apparatus having a toner recovery mechanism that sucks residual toner from the machine and collects the toner in a container, the toner feed amount is detected by measuring the number of times the toner feed driver is driven or the cumulative driving time. The toner collection amount is grasped and detected from the toner feed amount.

  In addition, an image forming apparatus according to the above-mentioned Japanese Patent Application Laid-Open No. 11-119534 includes a developing unit that visualizes an electrostatic latent image formed on a photoreceptor, a toner supply driving unit that supplies toner to the developing unit, An image forming apparatus comprising: transfer means for transferring a toner image visualized by a developing device to a transfer target; and a recovery container for recovering untransferred toner that has not been transferred to the transfer target. A toner recovery amount detection unit that detects a transfer toner recovery amount and outputs a full tank proximity signal when the detection amount reaches a preset full tank proximity amount, and the developer supply unit to the developer The toner replenishment amount detecting means for detecting the toner replenishment amount, and the development by the toner replenishment amount detecting means when the full tank proximity signal is output from the toner recovery amount detecting means. The detection of the toner replenishment amount is started and the detected replenishment amount is compared with a preset predetermined amount. When the replenishment amount reaches the predetermined amount, the collection container becomes full. And a control means for determining that it has been determined.

  However, in the developing device adopting the “trickle” developing method described above, when the toner concentration (TC) is high, the flowability of the developer is good, and a lot of the developer moves to the recovery area, and the developer is When the collected amount tends to increase and the toner concentration (TC) is low, the developer fluidity is poor, the amount of the developer moving to the collecting region is small, and the collected amount of the developer tends to be small. . As a result, in the developing device adopting the “trickle” developing system, the amount of collected developer varies greatly depending on the toner concentration (TC) of the developer in the developing device, and the full detection of the collecting container is accurately detected. Difficult to do.

For this reason, in the case of the developing device according to the above-mentioned Japanese Patent Application Laid- Open No. 11-119531, a recovery amount detection means for detecting that the deteriorated developer contained in the recovery container has reached a predetermined amount is provided, while the recovery amount A recovery control means is provided for stopping the operation of the developing device main body when it is determined that the developer supplied from the developer supplying means to the developing device main body has reached a predetermined amount after detection of the deteriorated developer by the detecting means. In this configuration, when the fullness of the collection container is detected only by the amount of developer replenished to the developing device main body, that is, the toner dispensing time, the developer is collected by the toner concentration (TC). The amount of variation is large, and it is not possible to accurately detect the fullness of the collection container.

  Therefore, in order to accurately detect the fullness of the recovery container, a fullness detection means for detecting the fullness of the recovery container is required, which increases the cost.

  On the other hand, in the conventional image forming apparatus, the amount of residual toner remaining on the photosensitive drum or intermediate transfer member depends on the amount of toner fog on the photosensitive drum, and the amount of toner fog is The correlation with the toner density (TC) is high. That is, when the toner density (TC) is high, the amount of toner fog on the photosensitive drum increases, and the amount of residual transfer toner that is removed from the photosensitive drum by the cleaning device and recovered in the waste toner recovery box is reduced. Become more. On the other hand, when the toner density (TC) is low, the amount of toner fog on the photosensitive drum decreases, and the amount of residual toner that is removed from the photosensitive drum by the cleaning device and recovered in the waste toner recovery box is reduced. Less.

  Therefore, as in the toner recovery amount detection method of the electrophotographic apparatus according to the above-mentioned JP-A-9-22237, the toner feed amount is detected by measuring the number of driving times or the driving cumulative time of the toner feed driving unit. The configuration is such that the toner recovery amount is grasped and detected from the feed amount, or the recovery container is full when the replenishment amount reaches a predetermined amount as in the image forming apparatus according to Japanese Patent Laid-Open No. 11-119534. Even in the case where the control means for determining that the waste toner collection box is full is detected only by the time when the toner is dispensed to the developing device, the amount of residual transfer toner is determined by the toner concentration (TC). As a result, the waste toner collection box is not fully detected.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and the object of the present invention is to provide a recovery container for recovering excess developer, an image carrier, an intermediate transfer member, and the like. An object of the present invention is to provide an image forming apparatus capable of accurately detecting the fullness of a collection container for collecting the residual transfer residual toner without causing an increase in cost.

That is, the invention described in claim 1 is a toner replenishing means for replenishing toner by rotating and driving a toner replenishing motor from a toner replenishing unit inside the developing device;
A collection container for collecting excess developer from the developer contained in the developing device;
Toner density detecting means for detecting the toner density of the developer contained in the developing device;
Full detection means for detecting fullness of the collection container based on the cumulative driving time of the toner supply motor of the toner supply means;
When detecting the fullness of the collection container by the fullness detection means, the toner drive time of the toner supply means of the toner supply means at the time of toner supply is cumulatively added to obtain the cumulative drive time. An image forming apparatus comprising: a correcting unit that corrects a driving time of a toner replenishing motor at the time of toner replenishment that is newly added based on a detection result of the toner density detecting unit during replenishment. .

According to a second aspect of the present invention, when the correction means determines that the toner density detected by the toner density detection means is relatively high, the newly added toner at the time of toner replenishment is added. The image forming apparatus according to claim 1 , wherein the correction is performed so that the driving time of the replenishing motor is increased.

  According to the present invention, full detection of a collection container for collecting excess developer and a collection container for collecting transfer residual toner remaining on an image carrier or an intermediate transfer body is accurately performed without causing an increase in cost. It is possible to provide an image forming apparatus capable of performing the above.

  Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1
FIG. 2 shows a tandem type full-color printer as an image forming apparatus according to Embodiment 1 of the present invention.

  In FIG. 2, reference numeral 01 denotes a main body of a tandem type full-color printer. The printer main body 01 is roughly divided into a print head device (Print Head Device) 02 that performs full-color image formation and this print. ROS (Raster Output Scanner) 03 as an exposure device that performs image exposure on the four photosensitive drums 11, 12, 13, and 14 as the image carrier of the head device 02, and the developing device 41 for each color of the print head device 02. , 42, 43, 44, four toner cartridges 04Y, 04M, 04K, 04C for supplying toner corresponding to the color, and a paper feed cassette 05 for supplying recording paper P as a recording medium to the print head device 02, From the print head device 02 The fixing device 06 that performs a fixing process on the recording paper P to which the toner image has been transferred, and the recording paper P on which the image is fixed on one side by the fixing device 06 are printed again with the print head device reversed. 02, a double-sided conveyance path 07 for conveying to the transfer unit, a manual sheet feeding unit 08 for feeding a desired recording sheet P from the outside of the printer main body 01, a control circuit for controlling the operation of the printer, and an image signal A controller 09 including an image processing circuit that performs image processing on the image and an electric circuit 10 including a high-voltage power supply circuit are provided. In FIG. 2, T denotes a discharge toilet that discharges the recording paper P on which an image is formed with the print side down, and this discharge toilet T is integrally disposed on the upper portion of the printer main body 01. ing.

  Of the various members disposed in the printer main body 01, ROS03 as an exposure device is image data corresponding to each color of yellow (Y), magenta (M), black (K), and cyan (C). The four semiconductor lasers (not shown) that are driven to light based on the above, and the f-θ lens and the polygon mirror for deflecting and scanning the four laser beams 31, 32, 33, and 34 emitted from these four semiconductor lasers Or a plurality of reflecting mirrors.

  FIG. 3 shows a print head device of a tandem type full-color printer as an image forming apparatus according to Embodiment 1 of the present invention. In addition, the arrow in FIG. 3 has shown the rotation direction of each rotation member.

  As shown in FIG. 3, the print head device 02 includes yellow (Y), magenta (M), black (K), and cyan (C) photosensitive drums (image carriers) 11, 12, 13, 14, image forming units 1, 2, 3, 4, and primary charging charging rolls (contact type charging devices) 21, 22, 23, 24 in contact with the photosensitive drums 11, 12, 13, 14, Refresher rolls 25, 26, 27, and 28 for temporarily removing toner remaining on the surfaces of the photosensitive drums 11, 12, 13, and 14, and yellow (Y), magenta (M), black (K), and cyan. ROS (exposure apparatus) 03 that irradiates laser beams 31, 32, 33, and 34 of each color (C) and electrostatic latent images formed on the photosensitive drums 11, 12, 13, and 14 are converted into yellow ( Y), magenta ( M), developing devices 41, 42, 43, and 44 for developing with toners of the respective colors of black (K) and cyan (C), and two of the four photosensitive drums 11, 12, 13, and 14 A first primary intermediate transfer drum (intermediate transfer member) 51 in contact with the drums 11 and 12, a second primary intermediate transfer drum (intermediate transfer member) 52 in contact with the other two photosensitive drums 13 and 14, and the above A secondary intermediate transfer drum (intermediate transfer member) 53 that contacts the first and second primary intermediate transfer drums 51 and 52 and a final transfer roll (transfer member) 60 that contacts the secondary intermediate transfer drum 53; Its main part is composed. Further, cleaning rollers 54, 55, 56 of a cleaning device for removing toner remaining on the surfaces of the intermediate transfer drums 51, 52, 53 are disposed on the surfaces of the intermediate transfer drums 51, 52, 53. .

  The photosensitive drums 11, 12, 13, and 14 are arranged in parallel to each other at a predetermined interval so as to have a common tangential plane M. Further, the first primary intermediate transfer drum 51 and the second primary intermediate transfer drum 52 are surfaces whose respective rotation axes are parallel to the photosensitive drums 11, 12, 13, and 14 and have predetermined symmetry planes as boundaries. They are arranged in a symmetrical relationship. Further, the secondary intermediate transfer drum 53 is arranged so that the rotation axis is parallel to the photosensitive drums 11, 12, 13, and 14.

  Signals corresponding to image data for each color of yellow (Y), magenta (M), black (K), and cyan (C) are rasterized by an image processing circuit provided in the controller 09 (see FIG. 2). To ROS03. In this ROS 03, the laser beams 31, 32, 33, and 34 of yellow (Y), magenta (M), black (K), and cyan (C) are modulated, and the corresponding photosensitive drums 11, 12, and 13 and 14 are irradiated.

  Around each of the photosensitive drums 11, 12, 13, and 14, an image forming process for each color is performed by a known electrophotographic method. First, as the photoconductor drums 11, 12, 13, and 14, for example, photoconductor drums using an OPC photoconductor with a diameter of 30 mm are used. These photoconductor drums 11, 12, 13, and 14 are, for example, It is rotationally driven at a rotational speed (peripheral speed) of 104 mm / sec. As shown in FIG. 3, the surfaces of the photosensitive drums 11, 12, 13, and 14 are formed by applying a DC voltage of about -840 V to charging rolls 21, 22, 23, and 24 as contact-type charging devices. For example, it is charged to about -300V. The contact-type charging device includes a roll type, a film type, a brush type, and the like, but any type may be used. In this embodiment, a charging roll generally used in an electrophotographic apparatus in recent years is employed. Further, in order to charge the surfaces of the photosensitive drums 11, 12, 13, and 14, in this embodiment, a charging method in which only DC is applied is used, but a charging method in which AC + DC is applied may be used.

  Thereafter, laser light 31 corresponding to each color of yellow (Y), magenta (M), black (K), and cyan (C) is applied to the surfaces of the photosensitive drums 11, 12, 13, and 14 by ROS03 as an exposure device. , 32, 33 and 34 are formed, and electrostatic latent images corresponding to the input image data for each color are formed. When the electrostatic latent image is written on the photosensitive drums 11, 12, 13, and 14, the surface potential of the image exposure portion is neutralized to about −60V or less.

  The electrostatic latent images corresponding to the respective colors of yellow (Y), magenta (M), black (K), and cyan (C) formed on the surfaces of the photosensitive drums 11, 12, 13, and 14 Are developed by developing devices 41, 42, 43, and 44, and yellow (Y), magenta (M), black (K), and cyan (C) colors are formed on the photosensitive drums 11, 12, 13, and 14, respectively. Visualized as a toner image.

  In this embodiment, as the developing devices 41, 42, 43, and 44, a magnetic brush contact type two-component developing method is adopted, but the scope of application of the present invention is not limited to this developing method, Needless to say, the present invention can be sufficiently applied to a non-contact type developing system.

  Next, the yellow (Y), magenta (M), black (K), and cyan (C) toner images formed on the photosensitive drums 11, 12, 13, and 14 are the first primary images. The primary transfer is electrostatically performed on the intermediate transfer drum 51 and the second primary intermediate transfer drum 52. The yellow (Y) and magenta (M) color toner images formed on the photoconductive drums 11 and 12 are formed on the first primary intermediate transfer drum 51 and the black ( The toner images of K) and cyan (C) are transferred onto the second primary intermediate transfer drum 52, respectively. Accordingly, on the first primary intermediate transfer drum 51, the single color image transferred from either the photosensitive drum 11 or 12 and the two color toner images transferred from both the photosensitive drums 11 and 12 are superimposed. A double color image is formed. In addition, similar single-color images and double-color images are formed on the second primary intermediate transfer drum 52 from the photosensitive drums 13 and 14.

  The surface potential necessary for electrostatically transferring the toner image from the photosensitive drums 11, 12, 13, and 14 onto the first and second primary intermediate transfer drums 51 and 52 is about +250 to 500V. . This surface potential is set to an optimum value depending on the charged state of the toner, the ambient temperature, and the humidity. The ambient temperature and humidity can be easily known by detecting the resistance value of a member having a characteristic that the resistance value varies depending on the ambient temperature and humidity. As described above, when the charge amount of the toner is in the range of −20 to 35 μC / g and is in a normal temperature and humidity environment, the surface potential of the first and second primary intermediate transfer drums 51 and 52 is + 380V is desirable.

The first and second primary intermediate transfer drums 51 and 52 used in this embodiment have an outer diameter of 60 mm, for example, and a resistance value of about 10 ⁸ Ω. The first and second primary intermediate transfer drums 51 and 52 are cylindrical rotating bodies having a single layer or a plurality of layers whose surfaces are flexible or elastic, and are generally made of Fe, Al, or the like. A low resistance elastic rubber layer (R = 10 ² to 10 ³ Ω) typified by conductive silicone rubber or the like is provided on a metal pipe as a metal core to a thickness of about 0.1 to 10 mm. Yes. Further, the outermost surfaces of the first and second intermediate transfer drums 51 and 52 are typically high release layers (R = 10 ⁵ to 10) having a thickness of 3 to 100 μm made of fluoro rubber in which fluororesin fine particles are dispersed. ⁹ Ω) and bonded with a silane coupling agent (primer). What is important here is the resistance value and the releasability of the surface, and the resistance value of the high release layer is about R = 10 ⁵ to 10 ⁹ Ω. It is not limited.

  The single-color or double-color toner images formed on the first and second primary intermediate transfer drums 51 and 52 in this way are electrostatically secondary-transferred onto the secondary intermediate transfer drum 53. Therefore, a final toner image from a single color image to a quadruple color image of yellow (Y), magenta (M), cyan (C), and black (K) is formed on the secondary intermediate transfer drum 53. Will be.

  The surface potential necessary for electrostatically transferring the toner image from the first and second primary intermediate transfer drums 51 and 52 onto the secondary intermediate transfer drum 53 is about +600 to 1200V. The surface potential is the same as when the toner is transferred from the photosensitive drums 11, 12, 13, and 14 to the first primary intermediate transfer drum 51 and the second primary intermediate transfer drum 52. Will be set to the optimum value. Further, since what is necessary for the transfer is a potential difference between the first and second primary intermediate transfer drums 51 and 52 and the secondary intermediate transfer drum 53, the first and second primary intermediate transfer drums 51 and 52 have different potentials. It is necessary to set the value according to the surface potential. As described above, the toner charge amount is in the range of −20 to 35 μC / g, the room potential is in a normal temperature and humidity environment, and the surface potentials of the first and second primary intermediate transfer drums 51 and 52 are about + 380V. In this case, the surface potential of the secondary intermediate transfer drum 53 is about + 880V, that is, the potential difference between the first and second primary intermediate transfer drums 51 and 52 and the secondary intermediate transfer drum 53 is about + 500V. It is desirable to set.

The secondary intermediate transfer drum 53 used in this embodiment has an outer diameter of 60 mm, which is the same as that of the first and second primary intermediate transfer drums 51 and 52, and has a resistance value of about 10 ¹¹ Ω. . Similarly to the first and second primary intermediate transfer drums 51 and 52, the secondary intermediate transfer drum 53 is a cylindrical rotating body having a single layer or a plurality of layers whose surface is flexible or elastic. In general, a low resistance elastic rubber layer (R = 10 ² to 10 ³ Ω) typified by conductive silicone rubber or the like is formed on a metal pipe as a metal core made of Fe, Al or the like. The thickness is set to about 0.1 to 10 mm. Further, the outermost surface of the secondary intermediate transfer drum 53 is typically formed by forming fluororubber in which fluororesin fine particles are dispersed as a high release layer having a thickness of 3 to 100 μm, and a silane coupling agent-based adhesive ( It is bonded with a primer. Here, the resistance value of the secondary intermediate transfer drum 53 needs to be set higher than that of the first and second primary intermediate transfer drums 51 and 52. Otherwise, the secondary intermediate transfer drum 53 charges the first and second primary intermediate transfer drums 51 and 52, and it is difficult to control the surface potential of the first and second primary intermediate transfer drums 51 and 52. Become. The material is not particularly limited as long as the material satisfies such conditions.

  Next, the final toner image from the single color image to the quadruple color image formed on the secondary intermediate transfer drum 53 is tertiary transferred onto the paper P passing through the paper transport path by the final transfer roll 60. The paper P passes through a paper transporting roll 90 through a paper feeding process (not shown), and is fed into the nip portion between the secondary intermediate transfer drum 53 and the final transfer roll 60. After this final transfer step, the final toner image formed on the paper is fixed by the fixing device 06, and a series of image forming processes is completed.

  4 and 5 show developing devices 41, 42, 43, and 44 used in the image forming units 1, 2, 3, and 4, respectively.

  Each of the developing devices 41, 42, 43, and 44 uses a two-component developer composed of yellow (Y), magenta (M), black (K), and cyan (C) toners and carriers of different colors. Basically, all are structured similarly. The developing devices 41, 42, 43, and 44 collect so-called “trickle” that collects excess developer in the developing devices 41, 42, 43, and 44 while supplying new developer at a predetermined timing. The development method is adopted.

  Inside these developing devices 41, 42, 43, 44, as shown in FIG. 4 and FIG. 5, two-component development comprising toner and carrier of the color of the corresponding image forming units 1, 2, 3, 4 is provided. The developer 46 is accommodated in a developing roll 48 disposed in the opening 49 on the photosensitive drum 11, 12, 13, 14 side of the developing device housing 47, and on the back side of the developing roll 48. The two developer conveying and stirring augers 50 and 51 and the layer thickness regulating blade 52 that regulates the layer thickness of the developer 46 conveyed by the developing roll 48 are configured. In this case, the developing roll 48 is composed of a developing sleeve (not shown) made of a nonmagnetic conductive member such as an aluminum alloy or stainless steel, and a magnet roll (not shown) arranged in a fixed state therein. . A partition plate 53 is provided between the two developer conveying / stirring augers 50 and 51.

  In addition, toner cartridges 04Y, 04M, 04K, and 04C (toner supply means configured as a toner replenishing unit configured separately from the developing devices 41, 42, 43, and 44 are provided inside the developing devices 41, 42, 43, and 44, respectively. 2), the toner for supplying toner is rotated by a replenishing auger (not shown) so that toner of a predetermined color is fed to one end of the developer conveying / stirring auger 51 as shown in FIG. 51a is supplied through a supply port 51b. The toner supplied into the developing devices 41, 42, 43, 44 is transported along the longitudinal direction of the developing devices 41, 42, 43, 44 by the developer conveying / stirring auger 51. The developer 46 is agitated and mixed with the developer 46, and is delivered to the other developer conveying and agitating auger 50 through a passage 54 provided at an end of the partition plate 53. The developer 46 delivered to the developer conveying / stirring auger 50 is agitated and mixed with the developer 46 while being conveyed along the axial direction of the developer conveying / stirring auger 50. Is again supplied to one developer conveying / stirring auger 51 through a passage 55 provided at the end of the first developer. As described above, the toner supplied into the developing devices 41, 42, 43, 44 together with the developer 46 in the developing devices 41, 42, 43, 44, the two developer conveying / stirring augers 50, 51, and agitated and mixed by the carrier 51, and triboelectrically charged to a predetermined charge amount by the carrier, a part of which is conveyed to the developing roll 48 by the developer agitating and conveying auger 50, and the photosensitive drums 11, 12,. 13 and 14 are used for developing electrostatic latent images.

  Further, the two-component developer 46 used for development in the developing devices 41, 42, 43, 44 is provided at the end of one developer conveying / stirring auger 50 as shown in FIG. Further, it is configured to gradually discharge from the discharge port 56 little by little. Further, at the end of the developer conveying / stirring auger 50, a discharging auger 50a having a small outer diameter and a fine pitch is set so as to convey excess developer to the discharging port 56. In addition to being provided, the upstream side of the discharge auger 50a is slightly smaller than the developer conveying and stirring auger 50 in order to prevent the developer from being unnecessarily discharged from the discharge port 56. An auxiliary auger 50b having an outer diameter is provided short. For example, the auxiliary auger 50b sets the direction of the conveying wings in the direction opposite to the developer conveying / stirring auger 50, thereby allowing the developer conveyed to the discharge port 56 by the developer conveying / stirring auger 50. Only the excess developer is pushed back and conveyed to the discharge port 56 side. Further, a partition plate 50c for separating the developer conveying / stirring auger 50 and the auxiliary auger 50b is provided on the ceiling of the developing devices 41, 42, 43, and 44.

  As a result, from the developing devices 41, 42, 43, and 44, when the developer in the developing device exceeds a predetermined amount, the excess developer is gradually discharged from the discharge port 56 little by little. It is configured. Further, the developer amount in the developing devices 41, 42, 43, 44 increases when the toner is replenished from the toner cartridges 04Y, 04M, 04K, 04C (see FIG. 2). When the toner is supplied from 04M, 04K, and 04C, the developer conveying / stirring augers 50 and 51 are also rotationally driven, so that the excess developer can be reliably discharged from the discharge port 56.

  The toner cartridges 04Y, 04M, 04K, and 04C may be configured to supply only the toner. However, when the used developer 46 is configured to be gradually discharged, the toner is a carrier. It is desirable that the developer is supplied with a slight mixing.

  Further, in this embodiment, as shown in FIGS. 1 and 5, the two-component developer is used as a toner concentration detecting means for detecting the toner concentration of the two-component developer 46 in the developing devices 41, 42, 43, and 44. A magnetic permeability sensor 57 that detects the toner concentration in 46 by magnetic permeability is used. As shown in FIG. 4, the magnetic permeability sensor 57 is located outside the developer conveying / stirring auger 51 in the developing device housing 47 and supplies toner along the axial direction of the developer conveying / stirring auger 51. It is attached to the outer wall near the end opposite to the side 51a. As shown in FIG. 6, a mounting portion 58 for mounting a magnetic permeability sensor 57 is provided on the outer wall of the developing device housing 47. The attachment portion has a flat surface 58 on the side where the magnetic permeability sensor 57 is attached, and the magnetic permeability sensor 57 is attached to the flat surface 58 by screws or the like.

  Excess developer discharged from the discharge ports 56 of the developing devices 41, 42, 43, 44 communicates with the discharge ports 56 of the developing devices 41, 42, 43, 44 as shown in FIG. Through 60, it is discharged into the collection container 61 and collected.

As shown in FIG. 2, when toner is supplied from the corresponding color toner boxes 04Y, 04M, 04K, and 04C to these developing devices 41, 42, 43, and 44, the supplied toner is developed. The agent agitating and conveying augers 50 and 51 are sufficiently agitated with the carrier and frictionally charged. Inside the developing roll 48, a magnet roll (not shown) having a plurality of magnetic poles arranged at a predetermined angle is arranged in a fixed state. The amount of developer conveyed to the vicinity of the surface of the developing roll 48 is regulated by the layer thickness regulating blade 52 to the developing unit. In this embodiment, the regulated developer amount is 30 to 50 g / m ² , and the charge amount of the toner existing on the developing roll 48 at this time is approximately about −20 to 35 μC / g. .

  The toner supplied onto the developing roll 48 is in the form of a magnetic brush composed of a carrier and toner by the magnetic force of the magnet roll, and this magnetic brush comes into contact with the photosensitive drums 11, 12, 13, and 14. ing. A developing bias voltage of AC + DC is applied to the developing roll 48 and the toner on the developing roll 48 is developed into an electrostatic latent image formed on the photosensitive drums 11, 12, 13, 14, whereby a toner image is formed. It is formed. In this embodiment, for example, the AC component of the developing bias voltage is set to 4 kHz, 1.5 kVpp, and the DC component is set to about −230V.

  In this embodiment, in the developing devices 41, 42, 43, and 44, a so-called "spherical toner" that is a substantially spherical toner is used, and an average particle diameter of about 3 to 10 μm is used. For example, the average particle diameter of the black toner is set to 8 μm, and the average particle diameter of the color toner is set to 7 μm.

By the way, the image forming apparatus according to this embodiment includes a toner replenishing unit that replenishes toner from the toner replenishing unit inside the developing device main body,
A collection container for collecting excess developer from the developer contained in the developing device main body;
Toner density detecting means for detecting the toner density of the developer contained in the developing device main body;
Full detection means for detecting the fullness of the collection container based on the cumulative drive time of the toner supply means;
And a correction unit that corrects the cumulative driving time of the toner replenishing unit based on the detection result of the toner concentration detection unit when the fullness detection unit detects the fullness of the collection container. .

  FIG. 1 is a block diagram showing a control circuit of a full-color printer configured as described above.

  In FIG. 1, reference numeral 200 denotes a control means for controlling the operation of the printer, which includes a CPU having functions as a full detection means and a correction means, 201 a controller for designating the number of printers, the size of the recording paper P, and the like. 57 is a toner density sensor, 202 is a ROM for storing programs and parameters executed by the CPU 200, 203 is a RAM for storing tables and the like used by the CPU 200, and 204 is a toner cartridge 04Y, 04M as shown in FIG. , 04K, 04C, toner supply motors for supplying toner to the developing devices 41, 42, 43, 44 are shown. The toner supply motor 204 is provided for each of the toner cartridges 04Y, 04M, 04K, and 04C.

  The RAM 203 is driven by a toner replenishing motor 204 so that the cumulative driving time when toner is replenished from the toner cartridges 04Y, 04M, 04K, 04C to the developing devices 41, 42, 43, 44, that is, toner dispensing. A correction table for correcting the toner dispensing time of the toner replenishing means based on the detection result of the toner density sensor when the CPU as the fullness detecting means detects the fullness of the collection container based on the time is stored. Yes.

  In the above configuration, in the full color printer according to this embodiment, it is possible to accurately detect the fullness of the collection container for collecting excess developer without incurring an increase in cost as follows. .

  That is, in the full-color printer according to this embodiment, as shown in FIGS. 2 and 3, when executing a print operation of a full-color or monochrome image, yellow (Y), magenta (M), black (K) In each of the cyan (C) image forming units 1, 2, 3, and 4, the toner in the developing devices 41, 42, 43, and 44 is sequentially consumed. 1 is detected by the toner density sensor 57, and when the toner density in the developing devices 41, 42, 43, and 44 becomes a predetermined value or less, as shown in FIG. By rotating and driving 204, toner of a predetermined color is supplied to the corresponding developing devices 41, 42, 43, and 44 from the toner cartridges 04Y, 04M, 04K, and 04C.

  The toner supply to the developing devices 41, 42, 43, 44 is performed by forming a toner patch on the photosensitive drum in addition to the toner density detected by the toner density sensor 57 and illustrating the density of the toner patch. It may be configured to perform detection based on the detection result of the density of the toner patch by the ADC sensor.

  At that time, in the above-described full-color printer, in principle, when a plurality of printing operations are being performed continuously, the printing operation is interrupted in the middle of the printing operation, and the toner replenishing operation is not performed. Then, after a series of printing operations is completed, a toner replenishing operation is executed.

  In the full-color printer, as shown in FIG. 1, when toner of a color corresponding to any of the developing devices 41, 42, 43, 44 is supplied, the corresponding toner cartridges 04Y, 04M, 04K, 04C are loaded. By rotating the provided toner replenishing motors 204Y to 204C (see FIG. 2), toner of a predetermined color is transferred from the toner cartridges 04Y, 04M, 04K, 04C to the corresponding developing devices 41, 42, 43, 44 is replenished.

At that time, the CPU 200 obtains the cumulative driving time T of the toner supply motor 204, that is, the toner dispensing time T which is a value obtained by cumulatively counting the driving time of the toner supply motor 204, and sets the toner dispensing time T to the toner dispensing time T. As appropriate, corrections are made, the excess developer recovery amount is obtained as shown in the following equation, and the fullness of the recovery container is detected.
Excess developer recovery amount = toner dispensing time T × correction coefficient

  However, the CPU 200 does not immediately detect the fullness of the collecting container based on the toner dispensing time T, but drives the toner supply motor 204 to start from any of the toner cartridges 04Y, 04M, 04K, and 04C. When the toner is supplied to the corresponding developing devices 41, 42, 43, 44, the toner concentration in the developing devices 41, 42, 43, 44 for supplying the toner is detected by the toner concentration sensor, and the toner concentration sensor The toner dispensing time T is corrected on the basis of the toner density detected by.

  It has been confirmed by experiments of the present inventors that the fluidity of the developer inside the developing devices 41, 42, 43, and 44 varies depending on the toner concentration. When the fluidity of the developer varies. Even if the toner supply motor 204 is driven for the same time, as shown in FIG. 8, the recovery amount of the excess developer recovered from the developing devices 41, 42, 43, and 44 changes according to the toner density. .

  Therefore, the CPU 200 drives the toner supply motor 204 to supply toner to the corresponding developing devices 41, 42, 43, and 44 from any of the toner cartridges 04Y, 04M, 04K, and 04C. As shown in FIG. 9, referring to the correction table stored in the RAM 203, the toner dispensing time T is corrected according to the toner density in the developing devices 41, 42, 43, and 44 when the toner is replenished. ing.

  When the CPU 200 detects that the toner density TC in the developing devices 41, 42, 43, and 44 at the time of toner replenishment is TC = 8%, the CPU 200 drives the motor 204 for toner replenishment. The time T1 is added as it is as the toner dispensing time T. On the other hand, when the CPU 200 detects that the toner density TC in the developing devices 41, 42, 43, and 44 at the time of toner replenishment is TC = 6%, it is 80%, that is, for toner replenishment. 0.8T1 obtained by multiplying the driving time T1 of the motor 204 by a factor of 0.8 is added as the toner dispensing time T. On the other hand, when the CPU 200 detects that the toner density TC in the developing devices 41, 42, 43, and 44 at the time of toner replenishment is TC = 10%, 120%, that is, the toner replenishment motor 204 1.2T1 obtained by multiplying the driving time T1 by a factor of 1.2 is added as the toner dispensing time T.

  Then, as shown in FIG. 10, the CPU 200 detects that the collection container is full when the toner dispensing time T corrected according to the toner concentration TC at the time of toner replenishment reaches a predetermined value. Through the user interface, a message prompting the user to replace the collection container with a new one is displayed and the printing operation is prohibited.

  As described above, the CPU 200 corrects the toner dispensing time T according to the toner concentration at the time of toner replenishment when detecting the fullness of the collection container based on the cumulative driving time T of the motor 204 for toner replenishment. Therefore, even if the developer fluidity changes depending on the toner concentration at the time of toner replenishment and the developer recovery amount fluctuates, the developer recovery amount can be accurately grasped. The fullness of the collection container can be detected with high accuracy.

  For this reason, the full color printer does not require a separate full detection sensor or the like as a member for detecting the fullness of the collection container, so that the cost can be reduced and the fullness of the collection container can be accurately detected. Therefore, in order to prevent the collected developer from overflowing from the collection container, an unnecessarily large collection container is used, or it is detected that the collection container is full early even though there is sufficient room for the collection container. There is no need, and the printer can be miniaturized.

Embodiment 2
FIG. 12 shows a second embodiment of the present invention. In the second embodiment, an image carrier that carries a toner image, and waste toner collection that collects transfer residual toner remaining on the image carrier. A container, a toner density detecting means for detecting the toner density of the developer contained in the developing device, and a fullness of the waste toner collecting container based on a cumulative number of pixels of the toner image formed on the image carrier. When detecting that the waste toner collecting container is full by the fullness detection means and the fullness detection means, the cumulative number of pixels of the toner image formed on the image carrier is used as the detection result of the toner density detection means. And a correcting means for correcting based on this.

That is, the second embodiment is configured such that the CPU 200 detects the fullness of the collection container 61 based on the cumulative number of pixels of the toner image formed on the photosensitive drums 11, 12, 13, and 14. When detecting that the collection container 61 is full, the CPU 200 determines the cumulative number of pixels of the toner image formed on the photosensitive drums 11, 12, 13, and 14 based on the detection result of the toner density detection sensor 57, for example. The correction is made according to the following equation.
Excess developer recovery amount = cumulative number of pixels in toner image x correction coefficient

  Here, depending on the cumulative number of pixels of the toner image, the cumulative transfer residual toner amount of the residual toner remaining on the photosensitive drums 11, 12, 13, and 14 changes. This cumulative transfer residual toner amount is shown in FIG. As shown in FIG. 4, the value varies depending on the toner density (TC). As in the case shown in FIG. 9, the correction coefficient is set to be large when the toner density is high, and small when the toner density is low.

  As described above, also in the second embodiment, even when the developer fluidity changes depending on the toner concentration at the time of toner replenishment and the developer recovery amount fluctuates, the recovery amount of the developer is reduced. It is possible to accurately grasp and accurately detect the fullness of the collection container.

  In this embodiment, when the full toner detection container detects the fullness of the waste toner collection container, the cumulative number of pixels of the toner image formed on the image carrier is corrected based on the detection result of the toner density detection means. The correction unit is configured to detect the fullness of the waste toner collection container and the excess developer collection container by the full detection unit in combination with the first and second embodiments. Further, the cumulative number of pixels of the toner image formed on the image carrier and the cumulative driving time of the toner replenishing means may be corrected based on the detection result of the toner density detecting means.

FIG. 1 is a block diagram showing a control circuit of a tandem type full color printer as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing a tandem type full-color printer as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 3 is a block diagram showing a print head device of a tandem type full color printer as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 4 is a block diagram showing a developing device of a tandem type full color printer as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 5 is a cross-sectional view showing a developing device of a tandem type full color printer as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 6 is a cross-sectional configuration diagram illustrating a mounting state of the toner density sensor of the developing device of the tandem type full color printer as the image forming apparatus according to the first embodiment of the present invention. FIG. 7 is a cross-sectional view showing a developing device of a tandem type full color printer as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 8 is a graph showing the relationship between the toner dispensing time and the collected amount. FIG. 9 is a chart showing correction coefficients for toner density. FIG. 10 is a graph showing the relationship between the corrected toner dispensing time and the collected amount. FIG. 11 is a graph showing the relationship between the toner dispensing time and the cumulative transfer residual toner amount.

Explanation of symbols

  04Y, 04M, 04K, 04C: toner cartridge, 11, 12, 13, 14: photosensitive drum, 41, 42, 43, 44: developing device, 57: toner density sensor, 200: CPU (full detection means / correction means) ), 61: collection container.

Claims (2)

Toner replenishing means for replenishing toner by rotating and driving a toner replenishing motor from a toner replenishing unit inside the developing device;
A collection container for collecting excess developer from the developer contained in the developing device;
Toner density detecting means for detecting the toner density of the developer contained in the developing device;
Full detection means for detecting fullness of the collection container based on the cumulative driving time of the toner supply motor of the toner supply means;
When detecting the fullness of the collection container by the fullness detection means, the toner drive time of the toner supply means of the toner supply means at the time of toner supply is cumulatively added to obtain the cumulative drive time. An image forming apparatus comprising: correction means for correcting a driving time of a toner replenishing motor at the time of newly replenished toner based on a detection result of the toner density detecting means at the time of replenishment . When the toner density detected by the toner density detection means is determined to be relatively high, the correction means corrects the driving time of the toner supply motor at the time of the newly added toner supply. The image forming apparatus according to claim 1 .

Images