JP2019061071A - Development container and image forming apparatus - Google Patents

Abstract

To improve the accuracy in detecting the concentration of toner in a developer, compared with a case where a magnet is attached to an attachment surface on the downstream side in the rotation direction of a blade member that has a tip passing from above to below at an interval with a detection surface of a detection member.SOLUTION: A development container 140 comprises: a second storage unit 154 that stores a developer G containing magnetic carrier and toner; a toner concentration sensor 170 that has a detection surface 172A exposed inside the second storage unit 154, and detects the concentration of toner in the developer G; a blade member 173 that is provided on a rotation shaft 143A arranged inside the second storage unit 154, and has a tip 173A passing from above to below at an interval with the detection surface 172A in association with the rotation of the rotation shaft 143A; and a magnet 200 that is attached to an attachment surface 175 on the upstream side in the rotation direction K2 of the blade member 173.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a developing container and an image forming apparatus.

  Patent Document 1 discloses a technology related to a developing device having a developer amount detecting unit on a developer conveyance path. In this prior art, a magnet is provided in the vicinity of the developer amount detection area, and the developer transport means is made of a magnetic material.

Japanese Utility Model Publication No. 05-016590

  It is known that a detection member whose detection surface is exposed to the container body of the developing container detects the toner concentration of the developer containing the magnetic carrier and toner contained in the container body.

  The present invention is compared with the case where the magnet is attached to the mounting surface on the downstream side in the rotational direction of the wing member whose tip portion passes from the upper side to the lower side at an interval from the upper side to the detection side of the detection member. It is an object to increase the detection accuracy of the toner concentration.

  According to the first aspect of the present invention, there is provided a container body containing a developer containing a magnetic carrier and a toner, a detection member for exposing a detection surface in the container body, and detecting a toner concentration of the developer; A wing member provided on a rotating shaft disposed inside, and having a tip end passing from the upper side to the lower side with an interval on the detection surface as the rotating shaft rotates, and an upstream side in the rotating direction of the wing member And a magnet attached to the attachment surface of the developer container.

  In the invention of claim 2, in the state in which the tip end of the wing member is closest to the detection surface, the attachment angle formed by the attachment surface with respect to an imaginary line orthogonal to the detection surface is an acute angle. It is a developing container as described in 4.

  The invention of claim 3 is the developing container according to claim 2, wherein the mounting angle is 20 ° or more.

  The invention of claim 4 is the developing container according to claim 2 or 3, wherein the mounting angle is 45 ° or less.

  In the invention of claim 5, when the magnet does not face the detection surface, the toner density value detected by the detection member is detected by the detection member when the magnet faces the detection surface. 3. The developer container according to claim 2, wherein the mounting angle is set to be larger than the value of the toner concentration.

  According to the invention of claim 6, in the state where the tip of the wing member is closest to the detection surface, the magnetic pole angle formed by the virtual line orthogonal to the magnetic pole direction of the magnet with respect to the virtual line orthogonal to the detection surface is The developing container according to claim 1, wherein the developing container is an acute angle.

  The invention of claim 7 is the developing container according to claim 6, wherein the magnetic pole angle is 20 ° or more.

  The invention according to claim 8 is the developer container according to claim 6 or 7, wherein the magnetic pole angle is 45 ° or less.

  According to the invention of claim 9, when the magnet does not face the detection surface, the toner density value detected by the detection member is detected by the detection member when the magnet faces the detection surface. The developer container according to claim 6, wherein the magnetic pole angle is set to be larger than the value of the toner concentration.

  The invention of claim 10 is the developer container according to any one of claims 1 to 9, wherein the magnet is provided radially inward of the tip end of the wing member.

  According to the invention of claim 11, when viewed from the direction along the imaginary line orthogonal to the detection surface, the magnet width along the rotation axis direction of the magnet is the detection surface width along the rotation axis direction of the detection surface The developer container according to any one of claims 1 to 10, which is a half or more of.

  According to the invention of claim 12, when viewed from the direction along the rotation axis, the detection surface is provided in the range of 90 ° to 180 ° when the upper side in the vertical direction passing the rotation axis is 0 °. The developer container according to any one of claims 1 to 11.

  The invention of claim 13 comprises an image carrier, charging means for charging the surface of the image carrier, and electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged image carrier, A developer contained in the developer container according to any one of claims 1 to 12 for developing the electrostatic latent image formed on the surface of the image carrier to form a toner image; An image comprising: transfer means for transferring the toner image to a transfer target; and toner supply means for supplying toner to the developing container based on the detection result of the toner concentration detected by the detecting member of the developing container. It is a forming device.

  According to the first aspect of the present invention, the detection accuracy of the toner concentration of the developer by the detection member is enhanced compared to the case where the magnet is attached to the attachment surface on the downstream side in the rotational direction of the wing member.

  According to the second aspect of the present invention, the detection accuracy of the toner concentration is enhanced as compared with the case where the mounting surface is parallel to the imaginary line orthogonal to the detection surface.

  According to the third aspect of the present invention, the detection accuracy of the toner concentration is enhanced as compared with the case where the mounting angle is less than 20 °.

  According to the fourth aspect of the present invention, the detection accuracy of the toner concentration is enhanced as compared with the case where the mounting angle is larger than 45 °.

  According to the fifth aspect of the present invention, the toner concentration value when the magnet is not facing the detection surface is equal to or less than the toner concentration value when the magnet is facing the detection surface. As compared with the case where the angle is set, the detection accuracy of the toner density becomes higher.

  According to the sixth aspect of the present invention, the detection accuracy of the toner concentration is higher than in the case where the magnetic pole direction of the magnet is parallel to the virtual line orthogonal to the detection surface.

  According to the seventh aspect of the present invention, the detection accuracy of the toner concentration is enhanced as compared with the case where the magnetic pole angle is less than 20 °.

  According to the eighth aspect of the present invention, the detection accuracy of the toner concentration is enhanced as compared with the case where the magnetic pole angle is larger than 45 °.

  According to the invention of claim 9, the magnetic pole angle is set such that the toner concentration value when the magnet is not facing the detection surface is equal to or less than the value of the toner concentration when the magnet is facing the detection surface The detection accuracy of the toner density is higher than in the case where is set.

  According to the tenth aspect of the present invention, the detection accuracy of the toner concentration is enhanced as compared with the case where the magnet protrudes outward in the radial direction with respect to the tip of the wing member.

  According to the invention of claim 11, the toner density is detected as compared with the case where the magnet width along the rotation axis direction of the magnet is less than half the detection surface width along the rotation axis direction of the detection surface. Accuracy is increased.

  According to the twelfth aspect of the present invention, the detection accuracy of the toner concentration is enhanced as compared with the case where the detection surface is provided at a position less than 90 °.

  According to the invention of claim 13, the image defect is suppressed as compared with the case where the developer is accommodated other than the developer container according to any one of claims 1 to 12.

FIG. 1 is an entire configuration view showing an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing an image forming unit of the image forming apparatus of FIG. 1; FIG. 2 is a cross-sectional view showing a developing device of the image forming apparatus of FIG. FIG. 4 is a plan view showing an essential part of a developing container of the developing device of FIG. 3; This relates to the first embodiment. FIG. 5 is a schematic view showing a state in which a tip end of a wing member of a stirring and conveying member of the developing container of FIG. 4 is closest to a detection surface. (1) to (5) of (A) in the developing container of the present embodiment are diagrams showing the tip of the wing member and the position of the magnet as the stirring and conveying member rotates, and (B) shows the position of (A) It is an output waveform of the voltage of the toner density sensor corresponding to the front-end | tip part of the wing member of (1)-(5), and the position of a magnet. (1) to (5) of (A) in the developing container of the comparative example are diagrams showing the tip of the wing member and the position of the magnet as the stirring and conveying member rotates, and (B) shows the position of (A) It is an output waveform of the voltage of the toner density sensor corresponding to the front-end | tip part of the wing member of (1)-(5), and the position of a magnet. The toner concentration detection value of the developer detected by the control device based on the output waveform of the toner concentration sensor shown in FIGS. 6B and 7B, and the difference between the toner concentration detection value and the actual measurement value Is a graph showing It is a graph which shows the relationship between angle theta 1 and angle theta 2, and detection accuracy.

<Overall Configuration of Image Forming Apparatus>
The image forming apparatus 1 according to the present embodiment shown in FIG. 1 is configured as a monochrome copying machine. The image forming apparatus 1 includes an automatic document feeder 2 for feeding originals (not shown) separated one by one to an upper portion of the apparatus main body 1A, a document fed by the automatic document feeder 2 and the like. And an image reading device 3 for reading an image of an original placed on a platen glass. Further, the image forming apparatus 1 is formed by an image forming apparatus 10 for forming a toner image developed with toner contained in the developer G (see FIG. 2) inside the apparatus main body 1A, and the image forming apparatus 10 A transfer device 15 for transferring the transferred toner image onto a recording sheet P as an example of a transferee and a recording medium; a sheet feeding device 50 for storing and transporting the recording sheet P to be supplied to the transfer position of the transfer device 15; And a fixing device 40 for fixing the toner image on the recording paper P transferred by the transfer device 15.

  The image forming apparatus 10 is provided with a rotating photosensitive drum 11 as an example of an image holder, and each apparatus as an example of the following toner image forming means is mainly provided around the photosensitive drum 11. It is arranged. The main devices are a charging device 12 for charging the peripheral surface (image holding surface) of the photosensitive drum 11 on which an image can be formed to a predetermined potential, and information of an image on the charged peripheral surface of the photosensitive drum 11 (Exposure signal) as an example of electrostatic latent image forming means for forming an electrostatic latent image having a potential difference by irradiating light based on (signal), and developing the electrostatic latent image with toner of developer G The developing device 14 as an example of developing means for forming a toner image, the transferring device 15 as an example of transferring means for transferring the toner image onto the recording paper P, and the image holding surface of the photosensitive drum 11 after transfer Drum cleaning device 16 and the like for removing and cleaning adhesion substances such as toner.

  The photosensitive drum 11 is formed by forming an image holding surface having a photoconductive layer (photosensitive layer) made of a photosensitive material on the peripheral surface of a grounded cylindrical or cylindrical base material. The photosensitive drum 11 is supported so that power is transmitted from a driving device (not shown) to rotate in a direction indicated by an arrow A.

  The charging device 12 is configured of a contact type charging roll disposed in contact with the photosensitive drum 11. The charging device 12 is supplied with a charging voltage. When the developing device 14 performs reversal development as the charging voltage, a voltage or current of the same polarity as the charging polarity of the toner supplied from the developing device 14 is supplied. Further, the charging device 12 is disposed so as to be in contact with a cleaning roll 121 for cleaning the surface thereof. As the charging device 12, a non-contact charging device such as scorotron disposed on the surface of the photosensitive drum 11 in a non-contact state may be used.

  The exposure device 13 is a peripheral surface of the photosensitive drum 11 after being charged with light configured according to image information of a document read by the image reading device 3 or image information input from an external personal computer or the like. To form an electrostatic latent image.

  The exposure device 13 of the present embodiment irradiates the photosensitive drum 11 with light according to image information by means of LEDs (Light Emitting Diodes) as a plurality of light emitting elements arranged along the axial direction of the photosensitive drum 11. It is an LED print head that forms an electrostatic latent image.

  The transfer device 15 is a contact type transfer device provided with a transfer roll that contacts and rotates around the photosensitive drum 11 and is supplied with a transfer voltage. As the transfer voltage, a direct current voltage having a polarity opposite to the charge polarity of the toner is supplied from a power supply (not shown).

  The fixing device 40 has a heating rotary body 41 in the form of a belt or a roll, which is heated by a heating unit so that the surface temperature is maintained at a predetermined temperature, and a state substantially along the axial direction of the heating rotary body 41 And a pressure rotary body 42 in the form of a roll or a belt which rotates in contact with a predetermined pressure.

  The sheet feeding device 50 is disposed at a lower position of the image forming device 10. The sheet feeding device 50 mainly includes a sheet storage body 51 for storing the recording sheets P in a stacked state, and delivery devices 52 and 53 for delivering the recording sheets P from the sheet storage body 51 one by one. Examples of the recording paper P include plain paper, OHP sheet, tracing paper, and the like.

  A sheet feeding and conveying mechanism configured by a sheet conveying roll pair 54 and 55 for conveying the recording sheet P delivered from the sheet feeding device 50 to the transfer position between the sheet feeding device 50 and the transfer device 15 A passage 56 is provided. The sheet conveyance roll pair 55 is, for example, a roll (resist roll) that adjusts the conveyance timing of the recording sheet P. Further, between the transfer device 15 and the fixing device 40, a sheet conveyance path 57 for conveying the recording sheet P transferred from the transfer device 15 after transfer to the fixing device 40 is provided. Further, at a portion close to the discharge opening of the recording paper P, a paper discharge roll for discharging the recording paper P after being fed out from the exit roll 43 of the fixing device 40 to the paper discharge unit 58 provided in the upper part of the apparatus main body 1A A pair 59 is arranged.

  A switching gate (not shown) for switching the sheet conveyance path is provided between the fixing device 40 and the sheet discharge roll pair 59. The paper discharge roll pair 59 is configured such that the rotation direction can be switched between the normal rotation direction (discharge direction) and the reverse rotation direction. Then, when forming an image on both sides of the recording paper P, after the rear end of the recording paper P on which the image is formed on one side passes the switching gate (not shown), the rotation direction of the paper discharge roll pair 59 is Switch from the normal direction (discharge direction) to the reverse direction. The recording paper P conveyed in the reverse rotation direction by the paper discharge roll pair 59 has its conveyance path switched by a switching gate (not shown), and is for double-sided printing formed along the side surface of the apparatus main body 1A. It is transported to the transport path 60. The duplex transport path 60 includes a plurality of sheet transport roll pairs 61 that transport the recording sheet P to the sheet transport roll pair 55 in a state where the front and back are reversed, and a transport guide (not shown).

  Further, on the upper part of the fixing device 40, the recording sheet P fed from the outlet roll 43 of the fixing device 40 after fixing is provided on the upper part of the apparatus main body 1A via the sheet conveying roll pair 62. The sheet discharge roll pair 64 discharged to the second sheet discharge portion 63, and the third one for face-up discharge provided on the upper side surface of the apparatus main body 1A with the recording sheet P fixed by switching the conveyance direction by the switching gate 65 A paper discharge roll pair 67 for discharging the paper to the paper discharge unit 66 is provided.

  Reference numeral 70 in FIG. 1 denotes a manual feed tray provided on the left side of the apparatus main body 1A of the image forming apparatus 1 so as to be openable and closable. Between the manual feed tray 70 and the sheet conveying roll pair 54, the feeding device 71 for feeding the recording sheets P stored in the manual feeding tray 70 one by one, and the recording sheets P fed by the feeding device 71 are separated one by one. The separating roll 72 is disposed.

  Further, reference numeral 145 in FIG. 1 denotes a toner cartridge which is arranged along a direction perpendicular to the paper surface and accommodates the developer G to be supplied to the developing device 14. Reference numeral 159 denotes a toner conveying member for conveying the developer G from the toner cartridge 145 to the developing container 140.

  Further, reference numeral 100 in FIG. 1 denotes a control device that comprehensively controls various operations of the image forming apparatus 1. The control device 100 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a bus (not shown), a bus for connecting the CPU and the ROM, and a communication interface.

  The control device 100 obtains the toner concentration of the developer G based on the detection value (voltage) detected by the toner concentration sensor 170 described later, and controls the toner conveyance member 159 appropriately based on the obtained toner concentration. Thus, the toner is conveyed from the toner cartridge 145 to the developing container 140 and supplied.

  As shown in FIG. 2, the developing device 14 holds the developer G in the developing container 140 in which a storage chamber for the developer G is formed, and conveys the developer to a developing area facing the photosensitive drum 11. While passing developer G between developer roll 141 as an example of a body, supply conveyance member 142 such as a screw auger which supplies developer roll 141 while stirring developer G, and supply conveyance member 142 while stirring An agitation / conveyance member 143 such as a screw auger for conveyance and a layer thickness regulation member 144 which regulates the amount (layer thickness) of the developer G held by the developing roll 141 are provided. The developer G of this embodiment is a two-component developer containing nonmagnetic toner and magnetic carrier. The developing device 14 will be described later.

  The drum cleaning device 16 is disposed so as to be in contact with the peripheral surface of the photosensitive drum 11 after transfer with a container-like main body 160 in which a part of the lower end surface is opened, and adheres such as residual toner A cleaning plate 161 for removing and cleaning the toner, and a delivery member 162 such as a screw auger for collecting the adhering matter such as toner removed by the cleaning plate 161 and transporting it to the developing device 14 and a recovery system (not shown); Is composed including. In the present embodiment, the adhered matter such as toner removed by the cleaning plate 161 is collected and sent out to the developing device 14 through the reuse device (not shown). As the cleaning plate 161, a plate-like member (for example, a cleaning blade) made of a material such as rubber is used.

  The recycling device (not shown) is removed by the cleaning plate 161 of the drum cleaning device 16 and conveyed to one end along the axial direction of the photosensitive drum 11 by the delivery member 162 such as a screw auger. It is a recycling unit that conveys the attached matter such as toner to the developing device 14 and uses it again for development.

<Image formation operation>
Next, a basic image forming operation by the image forming apparatus 1 will be described.

  When the image forming apparatus 1 receives command information of an image forming operation (print) request, the image forming apparatus 10, the transfer device 15, the fixing device 40, and the like start up. Further, according to the image forming operation, an image of a document (not shown) transported by the automatic document feeder 2 and an image of a document (not shown) placed on the platen glass are read by the image reader 3 as needed.

  In the image forming apparatus 10, first, the photosensitive drum 11 rotates in the direction indicated by the arrow A, and the charging device 12 charges the surface of the photosensitive drum 11 to a predetermined polarity (in the present embodiment, negative polarity) and potential. Subsequently, the exposure device 13 converts the image information of the document read by the image reading device 3 or the information of the image input into the image forming device 1 into black and white components on the surface of the photosensitive drum 11 after charging. Light is emitted based on the signal of the image obtained, and an electrostatic latent image is formed on the surface.

  Subsequently, the developing device 14 supplies from the developing roll 141 toner charged to a predetermined polarity (in the present embodiment, a negative polarity) to the electrostatic latent image formed on the photosensitive drum 11 to It adheres as it is and develops. By this development, the electrostatic latent image formed on the photosensitive drum 11 is visualized as a monochrome toner image developed with a black toner.

  Subsequently, when the toner image formed on the photosensitive drum 11 of the image forming device 10 is conveyed to the transfer position, the transfer device 15 transfers the toner image onto the recording paper P.

  Further, in the image forming apparatus 10 in which the transfer is completed, the drum cleaning device 16 removes the adhering matter such as toner so as to scrape it, and cleans the surface of the photosensitive drum 11. As a result, the imaging device 10 is enabled for the next imaging operation. The toner and the like scraped off by the drum cleaning device 16 are conveyed to the developing device 14 by the reuse device 180 and are again used for development.

  On the other hand, the sheet feeding device 50 feeds the recording sheet P to the sheet feeding conveyance path 56 in accordance with the image forming operation. In the sheet feeding / conveying path 56, a sheet conveying roll pair 55 as a registration roll feeds the recording sheet P to the transfer position at the transfer timing and supplies it.

  Subsequently, the recording sheet P on which the toner image has been transferred from the photosensitive drum 11 is conveyed to the fixing device 40 via a conveyance guide (not shown). In the fixing device 40, the recording sheet P after transfer is introduced into a contact portion between the rotating heating rotary member 41 and the pressing rotary member 42 and is passed, thereby performing a fixing process (heating and pressing). The unfixed toner image is fixed on the recording sheet P. Finally, in the case of the image forming operation for only forming an image on one side of the recording paper P after fixing is completed, the paper installed on the top of the apparatus main body 1A by the paper discharge roll pair 59 etc. It is discharged to the discharge unit 58 and the like.

  Further, when forming an image on both sides of the recording sheet P, the recording sheet P having the image formed on one side is not discharged to the sheet discharge unit 58 by the sheet discharge roll pair 59, and the sheet discharge roll pair 59 is the recording sheet P. While holding the rear end of the sheet, the rotation direction of the sheet discharge roll pair 59 is switched in the reverse direction. After the recording paper P conveyed in the reverse direction by the paper discharge roll pair 59 passes through the switching gate (not shown), it passes through the paper conveyance roll pair 61 or the double-sided conveyance path 60 provided with the conveyance guide etc. The sheet is conveyed again to the sheet conveying roll pair 55 in a state in which the front and back are reversed. The sheet conveying roll pair 55 feeds and supplies the recording sheet P to the transfer position in time with the transfer timing, forms an image on the back surface of the recording sheet P, and is installed on the top of the apparatus body 1A by the sheet discharge roll pair 59 or the like. The sheet is discharged to the sheet discharge unit 58 or the like.

  By the image forming operation described above, the recording sheet P on which the monochrome image is formed is output.

<Configuration of Developing Device>
As shown in FIG. 3, the developing container 140 constituting the developing device 14 is configured to include a lower housing 140A constituting the lower part of the developing container 140 and an upper housing 140B constituting the upper part of the developing container 140. There is.

  Inside the developing container 140, a developer storage chamber 151 for storing a two-component developer G containing nonmagnetic toner and magnetic carrier is formed. An opening 152 is provided in a region of the developing container 140 facing the photosensitive drum 11. Inside the developing container 140, a developing roller 141 as an example of a developer holding member is provided so as to be partially exposed to the opening 152 and to be rotationally driven in the arrow B direction. The developing roll 141 is configured to include a magnet roll 141A in which a plurality of magnetic poles are disposed, and a developing sleeve 141B rotatably disposed along the arrow direction on the outer periphery of the magnet roll 141A. The developing sleeve 141B is formed in a cylindrical shape by a nonmagnetic material such as aluminum or nonmagnetic stainless steel.

  On the outer side of the developing roller 141 in the X direction, a cylindrical layer thickness regulating member 144 for regulating the layer thickness of the developer G held by the developing roller 141 is disposed.

  Inside the developing container 140, a feed conveying member 142 composed of a screw auger (supply auger) or the like for supplying the developer G stored in the developer storage chamber 151 to the developing roll 141 is diagonally below the developing roll 141. It is arranged. The feeding and conveying member 142 is rotationally driven in the arrow K1 direction by a driving device (not shown).

  Further, in the inside of the developing container 140, a stirring and conveying member 143 formed of a screw auger (admix auger) or the like for conveying the developer G supplied to the inside of the developing container 140 while stirring is used. It is arranged on the back side. The stirring and conveying member 143 is rotationally driven in the direction of the arrow K2 by a driving device (not shown).

  In the present embodiment, since the idle gear is not provided between the feeding and conveying member 142 and the stirring and conveying member 143 for downsizing and cost reduction, the feeding and conveying member 142 and the stirring and conveying member as described above. It has a structure in which the direction of rotation rotates in the opposite direction to the direction 143.

  The feeding and conveying member 142 and the stirring and conveying member 143 have the same configuration. Here, as a representative, the configuration of stirring and conveying member 143 will be described.

  As shown in FIG. 4, the stirring and conveying member 143 includes a rotary shaft 143A formed in a cylindrical shape, and a conveying blade 143B integrally provided in a spiral shape on the outer periphery of the rotary shaft 143A. In addition, the conveyance blade 143B is a double spiral.

The developer G conveyed by the stirring conveyance member 143 is conveyed to the stirring conveyance member 143 at the downstream end of the conveyance direction (the arrow S direction) of the developer G (see FIG. 2). The conveyance blade (not shown) for back feeding for pushing back on the upstream side of the direction is provided at about 2 to 3 pitches. In addition, the description about the wing member 173 and the magnet 200 is mentioned later.

  As shown in FIG. 3, the lower housing 140 </ b> A includes a first accommodating portion 153 formed in a substantially semi-cylindrical cross section for accommodating the supply and conveyance member 142 and a container main body for accommodating the stirring and conveying member 143. A second housing portion 154 is provided. The first housing portion 153 and the second housing portion 154 are partitioned by a partition wall 155 provided in the lower housing 140A.

  At one end of the second housing portion 154 along the axial direction of the rotary shaft 143A, a supply portion (not shown) is provided to project. The developer G transported from the toner cartridge 145 (see FIG. 1) described above via the toner transport member 159 (see FIG. 1) is supplied to the second container 154 from the supply unit (not shown).

  The developer G is not transferred between the supply / conveying member 142 and the agitating / conveying member 143 at both end portions in the longitudinal direction of the partition wall 155 that divides the first accommodation portion 153 and the second accommodation portion 154, which is not illustrated. A first passage portion and a second passage portion are provided respectively.

The developer G having been conveyed to the axial end of the rotary shaft 143A by the stirring and conveying member 143 by the stirring and conveying member 143 is conveyed to the first accommodation portion 153 via the above-mentioned first passage portion (not shown). The developer is supplied to the developing roller 141 while being conveyed while being stirred by the supply / conveying member 142. Further, the developer G having the first storage portion 153 conveyed to the axial end of the rotary shaft 142A by the supply conveyance member 142 is transferred to the second storage portion 154 through the second passage portion (not shown). Is transported. That is, the developer G circulates and moves in the first containing portion 153 and the second containing portion 154.

  Further, the toner supplied to the second storage unit 154 from the supply unit (not shown) described above is stirred and mixed with the developer G stored in the developing container 140 while being conveyed by the stirring and conveying member 143. .

(Main part of developing container)
Next, the main part of the developing container 140 will be described.

  As shown in FIG. 3, the developing container 140 is provided with a toner concentration sensor 170 as an example of a detection member in the second accommodation portion 154 of the developing container 140. The toner concentration sensor 170 is a sensor that detects the toner concentration of the developer G by detecting the magnetic permeability of the developer G composed of nonmagnetic toner and magnetic carrier. The toner concentration sensor 170 is located on the upstream side of the first passage (not shown) at a position near the downstream end of the agitating and conveying member 143 along the conveyance direction of the developer G in the second container 154. Adjacent to each other.

  As shown in FIG. 4, the toner concentration sensor 170 includes a flat substantially rectangular sensor body 171 and a cylindrical detection portion 172 projecting from the side surface of the sensor body 171.

  As shown in FIGS. 3 and 4, the detection portion 172 of the toner concentration sensor 170 is fitted in an opening 154A provided in the wall 154B of the second accommodation portion 154 of the lower housing 140A. Thus, the detection surface 172A, which is an end surface of the detection unit 172, is exposed to the second accommodation unit 154.

  As shown in FIG. 4, when the toner concentration sensor 170 is viewed from the direction along the rotation shaft 143A, if the upper side in the vertical direction passing through the rotation shaft 14A is 0.degree., 90.degree. The detection surface 172A is attached so as to be exposed in the range of.

  As shown in FIG. 3 and FIG. 4, a plate-like wing member 173 protruding outward in the radial direction is provided on the rotation shaft 143A of the stirring and conveying member 143.

  As shown in FIG. 4, the wing members 173 are provided along the axial direction of the rotation shaft 143 </ b> A at adjacent (opposing) portions of the conveying blade 143 B of the double spiral of the stirring and conveying member 143.

  As shown in FIG. 3 and FIG. 4, the width direction of the plate-like wing member 173 is a direction along the rotation axis 143A.

  As shown in FIGS. 3 to 5, the wing member 173 is such that the tip end portion 173A is a toner along with the rotation of the stirring and conveying member 143 (see FIGS. 3 and 4) in the arrow K2 direction (see FIGS. 3 and 5). The detection surface 172A of the detection unit 172 of the concentration sensor 170 passes from the upper side to the lower side at an interval.

  As shown in FIG. 4, the pitch L of the conveying blade 143B of the stirring and conveying member 143 has a width D along the axial direction of the rotation axis 143A of the detection surface 172A of the detection portion 172 of the toner concentration sensor 170 (in this embodiment, the diameter And the half or more of the width D along the axial direction of the rotation shaft 143A. Therefore, the width d along the rotational axis direction of the tip end portion 173A of the wing member 173 is also set smaller than the width D of the detection surface 172A of the detection portion 172 of the toner concentration sensor 170 and 1/2 or more of the width D. ing. The center in the width direction of the detection surface 172A and the center in the width direction of the tip end portion 173A coincide with each other.

  As shown in FIGS. 3 to 5, the magnet 200 is attached to the attachment surface 175 which is the side surface on the upstream side in the rotational direction of the plate-like wing member 173. In the magnet 200, an S surface 202 (see FIG. 5), which is an S pole, is attached to the mounting surface 175. Further, the magnet 200 is attached radially inward of the tip end portion 173A of the wing member 173. Furthermore, the width along the axial direction of the rotation axis 143A of the magnet 200 is also the same as or substantially the same as the width d along the rotation axis direction of the tip portion 173A of the wing member 173. Therefore, the width along the axial direction of the rotation axis 143A of the magnet 200 is also smaller than the width D of the detection surface 172A of the detection portion 172 of the toner concentration sensor 170 and is set to 1/2 or more of the width D. In the present embodiment, the width of the magnet 200 is about 90% of the detection surface 172A. In addition, the magnet 200 has a cleaning function and a stirring function of the detection surface 172A by the magnetic brush.

  As shown in FIGS. 3 and 5, the shape of the plate-like wing member 173 seen from the axial direction of the rotary shaft 143A (see FIG. 3) is a tapered wedge shape in which the plate thickness becomes thinner toward the tip portion 173A. It has become.

  Specifically, as shown in FIG. 5, in the state where the tip end portion 173A of the wing member 173 is closest to the detection surface 172A of the toner concentration sensor 170, the side surface 177 on the downstream side of the rotation direction of the wing member 173 is a detection surface 172A. The mounting surface 175, which is parallel or substantially parallel to the imaginary line H orthogonal to the above, and is the side surface on the upstream side in the rotational direction of the wing member 173, has an angle θ1 with respect to the imaginary line H. Further, the angle θ1 is set in a range of 20 ° or more and less than 90 °.

  Explaining from another viewpoint, in a state where the tip end portion 173A of the wing member 173 is closest to the detection surface 172A, the virtual line GB orthogonal to the magnetic pole direction GA of the magnet 200 is with respect to the virtual line H orthogonal to the detection surface 172A. And has an angle θ2. Further, the angle θ2 is set in a range of 20 ° or more and less than 90 °.

  In the present embodiment, the angle θ1 and the angle θ2 described above are configured to be the same or substantially the same, and the angle θ1 and the angle θ2 are set to 28.6 ° ± 3 °. Further, the state in which the tip end portion 173A of the wing member 173 is closest to the detection surface 172A of the toner density sensor 170 is the state in which the center position 173B in the thickness direction of the tip portion 173A is closest to the detection surface 172A.

<Toner density control of developer>
Next, toner concentration control of the developer will be described.

  The developer G contained in the developing container 140 of the developing device 14 supplies toner from the developing roll 141 to the electrostatic latent image formed on the circumferential surface of the photosensitive drum 11 and causes it to adhere electrostatically The toner is consumed along with the process. The toner concentration of the developer G accommodated in the developing container 140 is detected by the toner concentration sensor 170 provided in the second accommodation portion 154.

  When the control device 100 determines that the toner concentration of the developer G detected by the toner concentration sensor 170 is lower than a predetermined lower limit or lower than the toner concentration required from the image information, the toner from the toner cartridge 145 The supply of toner to the developing container 140 is started by controlling the conveying member 159, and it is determined that the amount exceeds a predetermined upper limit value, or the supply is stopped when it is determined that the required toner concentration is exceeded.

  That is, the control device 100 detects the toner concentration of the developer G based on the output value (voltage) output from the toner concentration sensor 170, and appropriately controls the toner transport member 159 based on the detected toner concentration. Then, the developer G is supplied from the toner cartridge 145 to the developing container 140.

  The toner supplied to the developing container 140 is conveyed by the agitating and conveying member 143 to be agitated with the developer G contained in the developing container 140.

  (1) to (5) of FIG. 6A show the positions of the tip portion 173A of the wing member 173 and the magnet 200 as the stirring and conveying member 143 rotates. Specifically, in the leftmost view (1), the tip end portion 173A of the wing member 173 is close to the detection surface 172A, and the magnet 200 is opposed to the detection surface 172A. (2) is a view on the right side of the state (2) is a view rotated 1/4 in the K2 direction from the state of (1), and is a view on the right side of the state (3) is a state of (2) Is further a quarter of a turn in the K2 direction, and (4) on the right side is a view of a fourth turn in the K2 direction from the state of (3). And (5) which is the rightmost figure on the right side is a figure which is further rotated 1/4 in the K2 direction from the state of (4), and the tip of the wing member 173 which is the same as the leftmost figure (1) The portion 173A and the magnet 200 face the detection surface 172A.

  FIG. 6B is an output waveform of a voltage of the toner density sensor 170 corresponding to the position of the tip portion 173A of the wing member 173 and the magnet 200 in (1) to (5) of FIG. The maximum value (peak value) PQ in the output waveform is a state in which the tip end portion 173A of the wing member 173 and the magnet 200 in (2) to (4) in FIG. 6A do not face the detection surface 172A. Between (3) and (4). Then, the control device 100 detects the toner concentration of the developer G using the maximum value (peak value) PQ of the output waveform of the toner concentration sensor 170.

  As described above, the magnet 200 has a cleaning function and a stirring function of the detection surface 172A by the magnetic brush. Therefore, by providing the magnet 200, the retention of the developer G around the detection surface 172A is suppressed, and the detection accuracy of the toner concentration becomes high.

<Operation and effect>
Next, the operation and effects of the present embodiment will be described.

First, a developing container of a comparative example to which the present invention is not applied will be described.
As shown in FIG. 7A, in the developing container of the comparative example, the magnet 200 is attached to the side surface 177 (see also FIG. 5) on the downstream side in the rotational direction of the wing member 173.

  (1) to (5) of FIG. 7A show the positions of the tip end portion 173A of the wing member 173 and the magnet 200 along with the rotation of the stirring and conveying member 143 in the developing container of the comparative example. It corresponds to A).

  FIG. 7B is an output waveform of a voltage of the toner density sensor 170 corresponding to the position of the tip portion 173A of the wing member 173 and the magnet 200 of the comparative example of (1) to (5) of FIG. These correspond to FIG. 6 (B) described above.

  The maximum value (peak value) PQ in the output waveform is a state in which the tip end portion 173A of the wing member 173 and the magnet 200 in (1) and (5) in FIG. 7A face the detection surface 172A.

  The horizontal axis of the graph of FIG. 8 represents the toner density detection of the developer G detected by the control device 100 based on the maximum value PQ of the output waveform of the toner density sensor 170 shown in FIGS. 6B and 7B. It is a value.

  The vertical axis of the graph in FIG. 8 represents the toner concentration detection value of the developer G detected by the control device 100 and the developer G taken out of the developing container 140 (see FIG. 3) and the toner concentration is precisely measured with a separate measuring device. The difference between the measured value and the measured value is shown as a percentage (%). And it is a specification of this embodiment to put the difference within ± 1% (enclosed portion J enclosed by a dashed dotted line).

  In the image forming apparatus 1 of the present embodiment, the control device 100 controls the toner conveyance member 159 so that the toner concentration detection value of the developer G of the developing container 140 falls within the range of 6.0 or more and 11.0 or less. Then, the developer G is supplied from the toner cartridge 145 to the developing container 140, and the amount of toner is controlled. The toner concentration detection value (horizontal axis) is a weight ratio (wt%) at which the toner can be contained in the developer G.

  The black circles in the graph of FIG. 8 indicate the case of the developing container 140 of the present embodiment, and the black circles indicate the case of the developing container of the comparative example.

  In the developing container 140 of the present embodiment, the toner concentration detection value is 6 as the difference between the toner concentration detection value detected by the control device 100 based on the maximum value PQ of the output waveform of the toner concentration sensor 170 and the actual value. It is within ± 1% in the range of 0 or more and 11.0 or less.

  However, in the developing container of the comparative example, the difference between the toner density detection value detected by the control device 100 based on the maximum value PQ of the output waveform of the toner density sensor 170 and the actual measurement value is 6.0 for the toner density detection value. Above, in the range of 11.0 or less, it does not fall within ± 1%. In particular, as the toner concentration detection value increases, the difference between the toner concentration detection value and the actual measurement value increases.

  As described above, the magnet 200 is attached to the downstream side surface 177 of the wing member 173 in the rotation direction by attaching the magnet 200 to the mounting surface 175 that is the upstream side surface of the wing member 173 of the present embodiment in the rotation direction. As compared with the comparative example, the detection accuracy of the toner concentration of the developer G by the toner concentration sensor 170 becomes higher.

  Next, in a state where the tip end portion 173A of the wing member 173 is closest to the detection surface 172A of the toner concentration sensor 170, the angle θ1 of the mounting surface 175, which is the side surface on the upstream side in the rotational direction of the wing member 173 The relationship between the angle θ2 of the virtual line GB orthogonal to the magnetic pole direction GA of 200 with respect to the virtual line H and the detection accuracy will be described. The virtual line GB orthogonal to the magnetic pole direction GA is a line as viewed from the axial direction of the rotation shaft 143A.

  The table in FIG. 9 shows the relationship between the angles θ1 and θ2 and the detection accuracy. As described in the graph of FIG. 8, the detection accuracy is the difference between the toner concentration detection value and the actual measurement value when the toner concentration detection value of the developer G in the development container 140 is in the range of 6.0 to 11.0. Were evaluated as to whether they were within 1%. The Δ marks indicate that the detection accuracy is better than the comparative example ▲ in FIG. 8 although the difference between the two may not fall within ± 1% in some cases. The ○ marks indicate that the difference between the two is within ± 1%, like the 印 marks in the present embodiment of FIG. The crosses indicate that the detection accuracy is equal to or less than that of the comparative example ▲ in FIG.

  From the table of FIG. 9, the detection accuracy is higher than in the developing container of the comparative example, and the angle θ1 and the angle θ2 in which the difference between the toner density detection value and the actual measurement value falls within ± 1% are 45 ° at 20 ° or more. It is understood that it is the following.

  When the angle θ1 and the angle θ2 are 20 ° or more and 45 ° or less, the maximum value (peak value) PQ in the output waveform shown in FIG. 6 is (2) to (4) in FIG. This occurs when the tip end portion 173A of the wing member 173 and the magnet 200 do not face the detection surface 172A.

  On the other hand, when the angle θ1 and the angle θ2 are smaller than 20 ° or larger than 45 °, the maximum value (peak value) PQ in the output waveform is smaller than (2) in FIG. ) To (4) when the tip portion 173A of the wing member 173 and the magnet 200 do not face the detection surface 172A. However, when the toner concentration detection value is increased, the tip end portion of the wing member 173 in (1) and (5) of FIG. 6A is the same as when the magnet 200 is attached to the downstream side surface 177 of the wing member 173. The maximum value (peak value) PQ occurs when the 173A and the magnet 200 face the detection surface 172A. Since the maximum value (peak value) PQ in the output waveform changes in this manner, it is considered that the detection accuracy decreases.

  Here, when the magnet 200 is attached to the downstream side surface 177 of the wing member 173 in the rotation direction (K2 direction) as described above, the tip portion 173A of the wing member 173 and the magnet 200 face the detection surface 172A. The developer G is pressed against the detection surface 172A by the magnet 200 and compressed, and the bulk density becomes high. Therefore, when the tip end portion 173A of the wing member 173 and the magnet 200 face the detection surface 172A, the toner density detection value becomes high. Then, as the toner concentration increases, the bulk density increases and the toner concentration detection value increases. Therefore, as the toner concentration increases, the increase width of the maximum value (peak value) PQ in the output waveform increases. That is, the increase width of the toner concentration detection value becomes larger than the increase width of the actual measurement value, and the toner concentration detection value deviates from the actual measurement value. Therefore, as shown in the graph of FIG. 7, the difference between the toner concentration detection value and the toner concentration of the actually measured value separately measured is considered to be larger than ± 1%.

  On the other hand, as in the present embodiment, when the magnet 200 is attached to the mounting surface 175 which is the upstream side surface of the wing member 173 in the rotational direction (K2 direction), the tip portion 173A of the wing member 173 and the magnet 200 When the developer G faces the detection surface 172A, the developer G on the detection surface 172A is less compressed by the magnet 200, and the increase in bulk density is suppressed. Therefore, when the tip end portion 173A of the wing member 173 and the magnet 200 face the detection surface 172A, the toner concentration detection value also does not increase. Therefore, the maximum value (peak value) PQ in the output waveform is obtained when the tip end portion 173A of the wing member 173 and the magnet 200 do not face the detection surface 172A. For this reason, it is considered that the difference between the toner concentration detection value and the toner concentration of the actually measured value separately measured falls within ± 1% as shown in the graph of FIG.

  That is, the magnet 200 is attached to the attachment surface 175 which is the upstream side surface of the wing member 173 in the rotational direction (K2 direction), so that the magnet 200 reduces the compressive action of the developer G on the detection surface 172A. It is considered to specialize in the cleaning function and the stirring function of the detection surface 172A by the magnetic brush. Furthermore, as described above, by setting the angles θ1 and θ2 to 20 ° or more and 45 ° or less, the compression action of the detection surface 172A of the developer G is further reduced, and the detection accuracy is considered to be high.

  If this is described from another point of view, the angle θ1 of the mounting surface 175 which is the side surface on the upstream side of the wing member 173 in the rotational direction with respect to the virtual line H and the angle of the virtual line GB perpendicular to the magnetic pole direction GA of the magnet 200 It can be said that θ2 may be set so that the output waveform has the maximum value (peak value) PQ in a state where the magnet 200 does not face the detection surface 172A. Alternatively, the value of the toner concentration when the magnet 200 does not face the detection surface 172A (maximum value (peak value) PQ in the output waveform) is the value of the toner concentration when the magnet 200 faces the detection surface 172A It can be said that the angles θ1 and θ2 may be set to be larger than (the maximum value (peak value) PQ in the output waveform).

  In addition, when the magnet 200 protrudes radially outward beyond the tip end portion 173A of the wing member 173, the compression action of the detection surface 172A of the developer G increases, the bulk density increases, and the detection accuracy of the toner concentration decreases. . Therefore, when the magnet 200 is attached radially inward of the tip end portion 173A of the wing member 173, the detection accuracy of the toner concentration becomes high.

  Even if the width along the axial direction of the rotation axis 143A of the magnet 200 is made narrower than the width D of the detection surface 172A of the detection portion 172 of the toner concentration sensor 170 by 1/2 of the width D, It has been separately confirmed by experiments that the difference from the measured value is within ± 1%.

(Summary)
As described above, the magnet 200 is attached to the mounting surface 175 which is the upstream side surface of the wing member 173 in the rotational direction (K2 direction), the downstream side surface 177 of the wing member 173 in the rotational direction (K2 direction) The detection accuracy of the toner concentration of the developer G by the toner concentration sensor 170 is higher than when the magnet 200 is attached.

  A virtual line H in which the mounting surface 175 on the upstream side of the wing member 173 to which the magnet 200 is attached and the virtual line GB in a direction orthogonal to the magnetic pole direction GA of the magnet 200 are orthogonal to the detection surface 172A of the toner concentration sensor 170 Have an acute angle θ1 and an angle θ2. Therefore, as compared with the case where the mounting surface 175 and the virtual line GA are parallel to the virtual line H, the detection accuracy of the toner density by the toner density sensor 170 becomes higher.

  Further, compared with the case where the angle θ1 and the angle θ2 are less than 20 °, the detection accuracy of the toner density becomes higher.

  Further, compared with the case where the angle θ1 and the angle θ2 are larger than 45 °, the detection accuracy of the toner density becomes higher.

  Alternatively, since the output waveform has the maximum value (peak value) PQ when the magnet 200 does not face the detection surface 172A, the output waveform has a maximum value (peak value) when the magnet 200 faces the detection surface 172A. As compared with the case of PQ), the detection accuracy of the toner density becomes higher.

  In addition, since the magnet 200 is attached radially inward of the tip end portion 173A of the wing member 173. The detection accuracy of the toner concentration is higher as compared with the case where the end portion 173A is protruded.

  Further, when viewed from the direction along the rotation axis 143A, if the upper side in the vertical direction passing through the rotation axis 143A is 0 °, in the case of less than 90 ° (high position), the area where the developer G contacts the detection surface 172A is As this decreases, the detection accuracy of the toner concentration decreases. However, in the present embodiment, since the detection surface 172A is provided in the range of 90 ° or more and 180 ° or less, the detection accuracy of the toner concentration is higher than in the case of less than 90 °.

  Further, since the image forming apparatus 1 of the present embodiment uses the developing container 140, the supply accuracy of the toner to the developing container 140 by the toner conveying member 159 is enhanced. Therefore, the deterioration of the image quality such as the uneven image density due to the excessive toner supply to the developing container 140 or the excessive toner supply is suppressed. Alternatively, the developer G is prevented from overflowing from the developing container 140 due to excessive toner supply.

<Others>
The present invention is not limited to the above embodiment.

  In the above embodiment, the attachment surface 175 on the upstream side of the wing member 173 to which the magnet 200 is attached is orthogonal to the angle θ1 with respect to the virtual line H orthogonal to the detection surface 172A of the toner concentration sensor 170 The angle θ2 with respect to the imaginary line H in which the imaginary line GB in the direction perpendicular to the detection surface 172A of the toner concentration sensor 170 is set to an acute angle, 20 ° or more and 45 ° or less. However, it may be set using only one of the angle θ1 and the angle θ2. Further, both of the angle θ1 and the angle θ2 may be parallel to the imaginary line H orthogonal to the detection surface 172A. That is, the magnet 200 may be attached to at least the attachment surface 175 on the upstream side in the rotational direction K2 of the wing member 173.

  Further, for example, the configuration of the image forming apparatus is not limited to the configuration of the above embodiment, and various configurations can be made. For example, although the image forming apparatus 1 according to the present embodiment is configured as a monochrome copying machine, the present invention is not limited to this. It may be a printer having no copying function, or may be a color copier or a color printer.

  Furthermore, it goes without saying that the present invention can be implemented in various aspects without departing from the scope of the present invention.

1 Image Forming Apparatus 11 Photosensitive Drum (Example of Image Carrier)
12 Charging device (an example of charging means)
13 Exposure apparatus (an example of electrostatic latent image forming means)
14 Development device (an example of development means)
15 Transfer device (an example of transfer means)
100 Control device (an example of toner supply means)
140 developer container 143A rotary shaft 154 second housing portion (example of container main body)
159 Toner Conveying Member (An Example of Toner Supply Means)
170 Toner concentration sensor (example of detection member)
172A Detection surface 173A Tip 173 Blade member 175 Mounting surface 200 Magnet θ1 Angle (mounting angle)
θ2 angle (magnetic pole angle)
G developer
P Recording paper (an example of a receiver)

Claims (13)

A container main body containing a developer including a magnetic carrier and a toner;
A detection member having a detection surface exposed in the container body and detecting a toner concentration of the developer;
A wing member provided on a rotation shaft disposed in the container body, and having a tip end spaced from the detection surface and passing from the top to the bottom with rotation of the rotation shaft;
A magnet attached to the mounting surface on the upstream side in the rotational direction of the wing member;
Developer container. In the state where the tip of the wing member is closest to the detection surface,
The mounting angle formed by the mounting surface with respect to a virtual line perpendicular to the detection surface is an acute angle,
The developer container according to claim 1. The mounting angle is 20 ° or more.
The developing container according to claim 2. The mounting angle is 45 degrees or less.
The developing container according to claim 2 or 3. The value of toner density detected by the detection member when the magnet is not facing the detection surface is higher than the value of toner density detected by the detection member when the magnet is facing the detection surface The mounting angle is set to be large,
The developing container according to claim 2. With the tip of the wing member closest to the detection surface,
A magnetic pole angle formed by an imaginary line orthogonal to the magnetic pole direction of the magnet with respect to an imaginary line orthogonal to the detection surface is an acute angle.
The developer container according to claim 1. The magnetic pole angle is 20 ° or more.
The developer container according to claim 6. The magnetic pole angle is 45 degrees or less.
The developer container according to claim 6 or 7. The value of toner density detected by the detection member when the magnet is not facing the detection surface is higher than the value of toner density detected by the detection member when the magnet is facing the detection surface The magnetic pole angle is set to be large,
The developer container according to claim 6. The magnet is provided radially inward of the tip end of the wing member.
The developing container according to any one of claims 1 to 9. When viewed from a direction along a virtual line orthogonal to the detection surface,
The magnet width along the rotation axis direction of the magnet is 1/2 or more of the detection surface width along the rotation axis direction of the detection surface.
The developing container according to any one of claims 1 to 10. When viewed from the direction along the rotation axis,
When the vertical upper side passing through the rotation axis is 0 °,
The detection surface is provided in a range of 90 ° to 180 °;
The developing container according to any one of claims 1 to 11. An image carrier,
Charging means for charging the surface of the image carrier;
Electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged image carrier;
A developing unit for developing an electrostatic latent image formed on the surface of the image carrier with the developer accommodated in the developing container according to any one of claims 1 to 12 to form a toner image When,
A transfer unit configured to transfer the toner image to a transfer target;
Toner supply means for supplying toner to the developing container based on the detection result of the toner concentration detected by the detecting member of the developing container;
An image forming apparatus equipped with