JP2016012078A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve detection accuracy of a developer stored inside, without reducing productivity of a housing, in a developing device detecting concentration of a coloring agent stored inside by using a coil formed into a planar shape.SOLUTION: A developing device includes a magnetic permeability sensor 10 which outputs a signal having a frequency corresponding to magnetic permeability inside a casing 301 and a sensor attachment part 310 to which the magnetic permeability sensor 10 is attached. The magnetic permeability sensor 10 includes a coil which is formed on a substrate with a planar pattern and whose inductance is changed by the change of the magnetic permeability and is attached to the sensor attachment part 310, so that the coil faces a space which should detect the magnetic permeability. In the sensor attachment part 310, an opening 313 is provided in a part facing the coil, so that the inside and outside of the casing are connected as the space, in such a state that the magnetic permeability sensor 10 is attached. The magnetic permeability sensor is attached to close the opening 313.

Description

  The present invention relates to a developing device, and more particularly, to attachment of a sensor that detects the state of a developer.

  In recent years, there has been a tendency to digitize information, and image processing apparatuses such as printers and facsimiles used for outputting digitized information and scanners used for digitizing documents have become indispensable devices. Such an image processing apparatus is configured as an MFP (Multi Function Peripheral) that can be used as a printer, a facsimile, a scanner, and a copier by providing an imaging function, an image forming function, a communication function, and the like. Many.

  Among such image processing apparatuses, as an image formation output method, image formation output is performed by transferring an image formed by developing an electrostatic latent image formed by exposing a photoconductor to a sheet. An electrophotographic directional formula is known. Some electrophotographic systems use a two-component developer in which a carrier that is magnetic particles and a non-magnetic developer are mixed.

  In an image forming apparatus using such a two-component developer, only the developer is consumed by image formation, but in order to form a stable quality image, the concentration of the developer in the developing device. Must be kept within the proper range. Therefore, in an image forming apparatus using such a two-component developer, it is necessary to measure the concentration of the developer in the developing device.

  Therefore, an image forming apparatus using such a two-component developer is provided with a developer concentration detector for measuring the concentration of the developer in the developing device. As this developer concentration detector, one utilizing an LC oscillation circuit including a planar coil formed by a planar pattern on a substrate has been proposed and already known (for example, see Patent Document 1).

  The detection accuracy of the developer concentration detector using an LC oscillation circuit including a planar coil as disclosed in Patent Document 1 is affected by the distance from the surface on which the planar coil is formed to the position of the detection target. The That is, if the detection target and the planar coil are separated from each other by a certain distance, it becomes difficult to accurately detect the developer concentration.

  Since the developer density detector is mounted with the surface on which the planar coil is formed facing the housing of the developing device, the developer density detector is mounted between the interior of the housing housing the developer and the planar coil. In this case, an interval corresponding to the thickness of the casing is opened. Therefore, in consideration of the above-described detection accuracy of the developer concentration, it is preferable to make the thickness of the housing as thin as possible. On the other hand, when the thickness of the casing is reduced, the flow of the molding material at the time of molding the casing becomes worse, and it becomes difficult to obtain a good molded product, resulting in a decrease in mass productivity.

  The present invention has been made in consideration of the above circumstances, and in the developing device that detects the concentration of the developer accommodated in the interior using a coil formed in a flat shape, the productivity of the housing is reduced. An object of the present invention is to improve the detection accuracy of the developer accommodated in the interior without causing it.

  In order to solve the above problems, one embodiment of the present invention is a developing device in which a developer is transported by a magnetic substance inside a housing, and outputs a signal having a frequency corresponding to the magnetic permeability inside the housing. A permeability detector and a mounting portion to which the permeability detector is attached on the outer wall surface of the casing, the permeability detector being formed in a planar pattern on a substrate, and the permeability inside the casing Including a coil whose inductance changes due to the change of the coil, and the coil is attached to the attachment portion so as to face a space in which the magnetic permeability is to be detected inside the housing, and the magnetic permeability detector is attached to the attachment portion. In the state where the coil is formed, an opening is provided so that the inside and outside of the housing are connected as a space in a portion facing the coil, and the opening is configured to detect the magnetic permeability. Characterized in that it is closed by but is attached to the attachment portion.

  According to the present invention, in the developing device that detects the concentration of the developer accommodated in the interior using a coil formed in a flat shape, the development accommodated in the interior without reducing the productivity of the housing. It becomes possible to improve the detection accuracy of the agent.

1 is a diagram illustrating a mechanical configuration of an image forming apparatus including a developing device on which a magnetic permeability sensor according to an embodiment of the present invention is mounted. It is a sectional side view which shows the developing device by which the magnetic permeability sensor which concerns on embodiment of this invention is mounted. It is a perspective view which shows the developing device by which the magnetic permeability sensor which concerns on embodiment of this invention is mounted. It is a figure which shows the circuit structure of the magnetic permeability sensor which concerns on embodiment of this invention. It is a figure which shows the count aspect of the output signal of the magnetic permeability sensor which concerns on embodiment of this invention. It is a perspective view showing an outline of a magnetic permeability sensor concerning an embodiment of the present invention. It is a 6-face figure which shows the magnetic permeability sensor which concerns on embodiment of this invention. It is sectional drawing which shows an example of the attachment aspect of a magnetic permeability sensor. It is sectional drawing which shows the attachment aspect of the magnetic permeability sensor which concerns on embodiment of this invention. It is a figure which shows the notch of the casing side contact bonding layer which concerns on embodiment of this invention. It is sectional drawing which shows the attachment aspect of the magnetic permeability sensor which concerns on other embodiment of this invention. It is a figure which shows the flow of the developer inside the casing which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, an electrophotographic image forming apparatus using a two-component developer composed of a magnetic carrier and a non-magnetic developer will be described as an example. In the image forming apparatus according to the present embodiment, an LC oscillation circuit including a coil formed on a plane is used as a sensor for detecting the developer density inside the developing unit that develops an electrostatic latent image. It has a feature in the structure of the developing device for attaching the sensor to the developing device.

  FIG. 1 is a side view showing a mechanism for image forming output included in the image forming apparatus 100 according to the present embodiment. As shown in FIG. 1, the image forming apparatus 100 according to the present embodiment includes a configuration in which image forming units 106 </ b> K to 106 </ b> Y of respective colors are arranged along a conveyance belt 105 that is an endless moving unit. It is said to be a tandem type. That is, along the transport belt 105, which is an intermediate transfer belt on which an intermediate transfer image for transfer onto a sheet (an example of a recording medium) 104 that is separated and fed from the sheet feed tray 101 by the sheet feed roller 102 is formed. A plurality of image forming units (electrophotographic process units) 106Y, 106M, 106C, and 106K (hereinafter collectively referred to as image forming units 106) are arranged in order from the upstream side in the transport direction of the transport belt 105.

  Further, the sheet 104 fed from the sheet feeding tray 101 is stopped once by the registration roller 103 and is sent out to the image transfer position from the conveying belt 105 according to the image forming timing in the image forming unit 106.

  The plurality of image forming units 106Y, 106M, 106C, and 106K have the same internal configuration except that the colors of the toner images to be formed are different. The image forming unit 106K forms a black image, the image forming unit 106M forms a magenta image, the image forming unit 106C forms a cyan image, and the image forming unit 106Y forms a yellow image. In the following description, the image forming unit 106Y will be described in detail. However, since the other image forming units 106M, 106C, and 106K are the same as the image forming unit 106Y, the image forming units 106M, 106C, and 106K. For each of these components, instead of Y added to each component of the image forming unit 106Y, only the symbols distinguished by M, C, and K are displayed in the figure, and the description is omitted.

  The conveying belt 105 is an endless belt, that is, an endless belt that is stretched between a driving roller 107 and a driven roller 108 that are rotationally driven. The drive roller 107 is driven to rotate by a drive motor (not shown), and the drive motor, the drive roller 107, and the driven roller 108 function as a drive unit that moves the conveyance belt 105 that is an endless moving unit. .

  During image formation, the first image forming unit 106Y transfers a black toner image to the conveyance belt 105 that is driven to rotate. The image forming unit 106Y includes a photoconductor drum 109Y as a photoconductor, a charger 110Y disposed around the photoconductor drum 109Y, an optical writing device 111, a developing device 112Y, a photoconductor cleaner 113Y, and a static eliminator (not shown). ) Etc. The optical writing device 111 is configured to irradiate light to each of the photosensitive drums 109Y, 109M, 109C, and 109K (hereinafter collectively referred to as “photosensitive drum 109”).

  In the image formation, the outer peripheral surface of the photosensitive drum 109Y is uniformly charged by the charger 110Y in the dark, and then writing is performed by light from the light source corresponding to the yellow image from the optical writing device 111. An electrostatic latent image is formed. The developing device 112Y visualizes the electrostatic latent image with yellow toner, thereby forming a yellow toner image on the photosensitive drum 109Y.

  This toner image is transferred onto the conveyance belt 105 by the action of the transfer unit 115Y at a position (transfer position) where the photosensitive drum 109Y and the conveyance belt 105 come into contact or closest to each other. By this transfer, an image of yellow toner is formed on the conveyance belt 105. After the transfer of the toner image is completed, the photosensitive drum 109Y is wiped away with unnecessary toner remaining on the outer peripheral surface by the photosensitive member cleaner 113Y, and then is neutralized by the static eliminator, and waits for the next image formation.

  As described above, the yellow toner image transferred onto the conveying belt 105 by the image forming unit 106Y is conveyed to the next image forming unit 106M by driving the rollers of the conveying belt 105. In the image forming unit 106M, a magenta toner image is formed on the photosensitive drum 109M by the same process as the image forming process in the image forming unit 106Y, and the toner image is superimposed and transferred onto the already formed yellow image. Is done.

  The yellow and magenta toner images transferred onto the conveying belt 105 are further conveyed to the next image forming units 106C and 106K, and the cyan toner image formed on the photosensitive drum 109C and the photosensitive member are subjected to the same operation. The black toner image formed on the body drum 109K is superimposed and transferred on the already transferred image. Thus, a full-color intermediate transfer image is formed on the conveyance belt 105.

  The sheets 104 stored in the sheet feed tray 101 are sent out in order from the top, and the intermediate transfer image formed on the conveyance belt 105 is transferred at a position where the conveyance path is in contact with or closest to the conveyance belt 105. It is transferred onto the paper. As a result, an image is formed on the surface of the sheet 104. The sheet 104 on which the image is formed on the sheet surface is further conveyed, the image is fixed by the fixing device 116, and then discharged to the outside of the image forming apparatus.

  A belt cleaner 118 is provided for the conveyor belt 105. As shown in FIG. 1, the belt cleaner 118 is a cleaning blade pressed against the conveyance belt 105 on the downstream side of the transfer position of the image from the conveyance belt 105 to the paper 104 and upstream of the photosensitive drum 109. And a developer remover that scrapes off toner adhering to the surface of the conveyor belt 105.

  Among the configurations of the image forming apparatus 100 having such a configuration, the magnetic permeability sensor 10 according to the present embodiment is provided in the developing device 112. The configuration of the developing device 112 is shown in FIG. FIG. 2 is a side sectional view showing a configuration around the photosensitive drum 109 including the developing device 112 according to the present embodiment. The developing device 112 includes a supply chamber conveyance member 302 and a collection chamber conveyance member 303 for agitating and conveying the developer, and a rotating member such as a developing roller 304 and other members in a casing 301 that is a casing.

  The developing roller 304 is disposed so as to form the developing nip region A by facing the photosensitive drum 109 in a position between 2 o'clock and 3 o'clock (position of 2:30). A portion of the casing 301 corresponding to the portion facing the photosensitive drum 109 is opened to expose the developing roller 304.

  The developer in the casing 301 is conveyed to the development nip area A by the development roller 304. In the development nip region A, the toner in the developer adheres to the electrostatic latent image formed on the surface of the photosensitive drum 109 and is developed (visualized) as a toner image. The toner image moves downstream as the photosensitive drum 109 rotates and reaches a portion facing the transfer device 115. As described with reference to FIG. 1, the transfer unit 115 is disposed at the bottom of the photosensitive drum 109 at the 6 o'clock position. In this example, the transfer device 115 is composed of a rotating body, but is not limited to a rotating body, and may be a corona discharge type. A region where the photosensitive drum 109 and the transfer device 115 face each other is referred to as a transfer region B.

  The developer after the toner is attached to the photosensitive drum 109 has a lower toner concentration in the developer. For this reason, if the developer having the lowered toner density is transported again to the development nip region A without being separated from the developing roller 304 and used for development, there arises a problem that a target image density cannot be obtained.

  In order to prevent this, in this example, the developer is separated from the developing roller 304 in the agent separation region C after development. The developer separated from the developing roller 304 is then sufficiently agitated and mixed in the casing 301 so that the target toner density and toner charge amount are obtained.

  Thus, the developer having the target toner concentration and charge amount is supplied to the developer storage space D by the supply chamber conveying member 302. At that time, a flow-in prevention wall 305 is provided between the supply chamber conveyance member 302 and the developer storage space D. The inflow prevention wall 305 prevents the developer supplied from the supply chamber conveying member 302 disposed above the developing roller 304 from being pushed directly into the developer storage space D.

  The inflow prevention wall 305 is formed as a part of a partition plate 306 that partitions the developer transport space by the supply chamber transport member 302 and the developer transport space by the recovery chamber transport member 303. The developer supplied to the storage space D is adjusted to a predetermined thickness by passing through the developer regulating member 307 and is conveyed to the development nip region A while forming a magnetic brush.

  In FIG. 3, the density distribution of the magnetic flux generated by the developing roller 304 is indicated by a broken line. The developing roller 304 includes a developing sleeve and a magnet roller inside the developing sleeve, and the magnet roller is configured to generate three magnetic poles (magnetic force distribution).

  Specifically, a magnetic pole of a portion (a region corresponding to the development nip region A) opposed on a line connecting the center of the developing roller 304 and the center of the photosensitive drum 109 is referred to as a P1 pole (developing pole). The magnetic poles are referred to as a P2 pole (casing counter pole) and a P3 pole (developer regulating member counter pole) in order of the rotation direction of the developing roller indicated by the direction of rotation.

  The polarity is changed from the P1 pole to the N, S, and S poles, but these poles may have opposite polarities. The P1 pole is a development pole and faces the photosensitive drum 109. P2 faces the casing 301, and P3 faces the developer regulating member 307.

  FIG. 3 shows an overview of the developing device 112, and is a perspective view in a state where the image forming apparatus 100 is mounted upside down. The longitudinal direction of the developing device 112 shown in FIG. 3 is a direction perpendicular to the drawing of FIG. 1, that is, a direction parallel to the belt surface of the conveying belt 105 and perpendicular to the conveying direction of the belt. The developing device 112 is provided with a supply chamber conveying member 302 and a collection chamber conveying member 303 which are conveying screws for conveying a mixture of carrier and toner which are the developer filled therein, in the longitudinal direction.

  The supply chamber conveyance member 302 and the collection chamber conveyance member 303 are rotated in opposite directions, so that the developer filled therein is spread over the entire longitudinal scanning direction described above inside the developing device 112. Has been. That is, the entire inside of the developing device 112 is used as a developer accommodating portion.

  The developer transported by the supply chamber transport member 302 and the recovery chamber transport member 303 inside the developing device 112 is received by the transport path of the supply chamber transport member 302 from the transport path of the recovery chamber transport member 303 at the end in the longitudinal scanning direction. Passed. For this reason, the partition plate 306 inside the casing 301 described with reference to FIG. 2 is provided with connection holes for connecting the spaces at both ends in the longitudinal scanning direction.

  The space of the connecting hole, that is, the space where the developer moves between the respective transport paths at the end portion in the longitudinal scanning direction of the developing device 112 (hereinafter referred to as “developer moving space”) is the most of the developer. A space with a wide filling range. The magnetic permeability sensor 10 according to this embodiment is attached to a sensor attachment position 310 shown in FIGS. 2 and 3 in order to detect the toner density in the developer movement space. Thereby, the magnetic permeability sensor 10 is used as a developer concentration detector.

  The developer inside the developing device 112 is consumed by transferring the developer toner from the developing roller 304 to the photosensitive drum 109 by repeating the developing operation as described in FIG. The amount, that is, the toner concentration decreases. Therefore, it is necessary to supply toner to the developer in the apparatus from the outside of the developing device 112.

  In the developing device 112 according to this embodiment, toner is supplied from a supply port 311 shown in FIG. Here, in the transport path by the collection chamber transport member 303, the developer is transported from the supply port 311 side shown in FIG. On the other hand, in the transport path by the supply chamber transport member 302, the developer is transported from the sensor attachment position 310 side shown in FIG. 3 toward the supply port 311 side.

  According to such a conveyance path, the toner supplied from the replenishing port 311 is not immediately supplied from the conveyance path by the supply chamber conveyance member 302 to the developer storage space D, and the carrier is agitated by the collection chamber conveyance member 303. Then, the toner is conveyed while being mixed and then supplied to the developer storage space D from the conveyance path by the supply chamber conveyance member 302. Accordingly, since a developer having a stable toner concentration is used for development, it is possible to prevent a deterioration in image quality due to a change in toner concentration.

  Next, the internal configuration of the magnetic permeability sensor 10 according to the present embodiment will be described with reference to FIG. As shown in FIG. 4, the magnetic permeability sensor 10 according to the present embodiment is an oscillation circuit based on a Colpitts LC oscillation circuit, and includes a planar pattern coil 11, a pattern resistor 12, a first capacitor 13, and a second capacitor. 14, a feedback resistor 15, unbuffered ICs 16 and 17, and an output terminal 18.

  The planar pattern coil 11 is a planar coil configured by signal lines patterned on a plane on a substrate constituting the magnetic permeability sensor 10. As shown in FIG. 4, the planar pattern coil 11 has an inductance L obtained by the coil. In the planar pattern coil 11, the value of the inductance L varies depending on the magnetic permeability of the space facing the plane on which the coil is formed. As a result, the magnetic permeability sensor 10 according to the present embodiment is used as a magnetic permeability detector that oscillates a signal having a frequency corresponding to the magnetic permeability of the space where the coil surfaces of the planar pattern coil 11 face each other. Here, the magnetic permeability of the space facing the plane on which the coil is formed is the magnetic permeability within the range in which the magnetic flux of the magnetic permeability sensor acts.

The pattern resistor 12 is a resistor configured by a signal line pattern formed on the substrate in the same manner as the planar pattern coil 11. The pattern resistor 12 according to the present embodiment is a pattern formed in a zigzag shape, thereby creating a state in which current does not flow more easily than a linear pattern. Providing this pattern resistor 12 is one of the gist according to the present embodiment. In other words, the zigzag folded shape is a shape folded so as to reciprocate a plurality of times in a predetermined direction. As shown in FIG. 4, the pattern resistor 12 has a resistance value _{R P.} As shown in FIG. 4, the planar pattern coil 11 and the pattern resistor 12 are connected in series.

  The first capacitor 13 and the second capacitor 14 are capacitors that together with the planar pattern coil 11 constitute a Colpitts LC oscillation circuit. Therefore, the first capacitor 13 and the second capacitor 14 are connected in series with the planar pattern coil 11 and the pattern resistor 12. A resonance current loop is constituted by a loop constituted by the planar pattern coil 11, the pattern resistor 12, the first capacitor 13 and the second capacitor 14.

The feedback resistor 15 is inserted to stabilize the bias voltage. Due to the functions of the unbuffered IC 16 and the unbuffered IC 17, the potential fluctuation of a part of the resonant current loop is output from the output terminal 18 as a rectangular wave corresponding to the resonant frequency. With such a configuration, the magnetic permeability sensor 10 according to the present embodiment oscillates at a frequency corresponding to the inductance L, the resistance value R _P , and the electrostatic capacitance C of the first capacitor 13 and the second capacitor 14.

The inductance L also changes depending on the presence of the magnetic substance in the vicinity of the planar pattern coil 11 and its concentration. Therefore, the permeability in the space near the planar pattern coil 11 can be determined from the oscillation frequency of the permeability sensor 10. Further, as shown in FIG. 4, in designing the oscillation frequency of the magnetic permeability sensor 10 with high accuracy, the circuit resistance _RL generated by a signal line or the like constituting the circuit cannot be ignored. The frequency corresponding to the parameter value of each part constituting the magnetic permeability sensor 10 will be described in detail later.

FIG. 5 is a diagram illustrating an aspect of the count value of the output signal of the magnetic permeability sensor 10 according to the present embodiment. If there is no change in the concentration of the magnetic material present around the magnetic permeability sensor 10, the magnetic permeability sensor 10 continues to oscillate at the same frequency in principle. As a result, as shown in FIG. 5, the count value of the counter uniformly increases with time, and as shown in FIG. 5, the timing of each of t ₁ , t ₂ , t ₃ , t ₄ , and t _5. , Count values such as aaaah, bbbbbh, cccch, ddddh, AAAAh are acquired.

By calculating the count value at each timing based on the periods T ₁ , T ₂ , T ₃ , and T ₄ shown in FIG. 5, the frequency in each period is calculated. For example, when a frequency is calculated by outputting an interrupt signal when a reference clock corresponding to 2 (msec) is counted, T ₁ and T shown in FIG. 5 are obtained by dividing the count value in each period by 2 (msec). The oscillation frequency f (Hz) of the magnetic permeability sensor 10 in each of the periods T ₂ , T ₃ , and T ₄ is calculated.

Further, as shown in FIG. 5, if the upper limit of the count value of the counter is FFFFh, when calculating the frequency in the period _{T 4,} a value obtained by subtracting ddddh from FFFFh, the sum of the values of the AAAAh 2 (msec ), The oscillation frequency f (Hz) can be calculated.

  As described above, in the image forming apparatus 100 according to the present embodiment, the frequency of the signal oscillated by the magnetic permeability sensor 10 is acquired, and an event corresponding to the oscillation frequency of the magnetic permeability sensor 10 is determined based on the acquisition result. be able to. And in the magnetic permeability sensor 10 which concerns on this embodiment, the inductance L changes according to the density | concentration of the magnetic body which exists in the space where the coil surface of the plane pattern coil 11 opposes, and is output from the output terminal 18 as a result. The frequency of the signal changes. As a result, the controller 1 can detect the concentration of the magnetic material present in the space where the coil surfaces of the planar pattern coil 11 face each other.

  Therefore, at the sensor mounting position 310 shown in FIG. 3, the coil surface of the planar pattern coil 11 is disposed so as to face the developer movement space, so that the development in the developing device 112 is developed based on the oscillation signal of the magnetic permeability sensor 10. It becomes possible to detect the toner concentration of the agent. Hereinafter, the form of the magnetic permeability sensor 10 and the manner of attaching the magnetic permeability sensor 10 to the developing device 112 will be described.

  FIG. 6 is a perspective view showing an overview of the magnetic permeability sensor 10 according to the present embodiment. In FIG. 6, the surface on which the planar pattern coil 11 and the pattern resistor 12 described in FIG. 4 are formed, that is, the detection surface facing the space where the magnetic permeability is to be detected is directed to the upper surface.

  As shown in FIG. 6, on the detection surface on which the planar pattern coil 11 is formed, the pattern resistor 12 connected in series with the planar pattern coil 11 is patterned. As described in FIG. 4, the planar pattern coil 11 is a signal line pattern formed in a spiral shape on a plane. Further, the pattern resistor 12 is a signal pattern formed in a zigzag pattern on the plane, and the function of the magnetic permeability sensor 10 as described above is realized by these patterns, and the visual resistance as shown in FIG. It becomes an interesting pattern.

  A portion formed by the planar pattern coil 11 and the pattern resistor 12 is a magnetic permeability detecting unit in the magnetic permeability sensor 10 according to the present embodiment. When the magnetic permeability sensor 10 is attached to the developing device 112, the detection unit is attached so as to face the developer movement space described above.

  7A to 7E are six views showing the magnetic permeability sensor 10 according to the present embodiment. As shown in FIGS. 7B to 7D, the first capacitor 13, the second capacitor 14, the feedback resistor 15, the unbuffered ICs 16 and 17, and the output terminal 18 described in FIG. 4 constitute the magnetic permeability sensor 10. In the board | substrate to be formed, it forms in the surface on the opposite side to the surface in which the planar pattern coil 11 and the pattern resistance 12 were formed.

  Thus, the magnetic permeability sensor 10 is brought into contact with the surface of the magnetic permeability sensor 10 so that the surface on which the planar pattern coil 11, which is a portion exhibiting a sensing function, is opposed to the space where the magnetic permeability is to be detected. Can be arranged.

  Further, on the surface where these components are mounted, electronic components and signal lines are not mounted on the portion where the planar pattern coil 11 and the pattern resistor 12 are formed on the back side. Thereby, it is possible to prevent the magnetic flux generated by other electronic components and signal lines from affecting the planar pattern coil 11 and the pattern resistor 12, and improve the accuracy of detecting the magnetic permeability.

  FIG. 8 is a diagram illustrating an example of an attachment mode of the magnetic permeability sensor 10 at the sensor attachment position 310. As shown in FIG. 8, the magnetic permeability sensor 10 is attached to the casing 301 via the adhesive layer 312 with the surface on which the planar pattern coil 11 is formed facing the sensor attachment position 310. As a result, as shown in FIG. 8, the planar pattern coil 11 is disposed so as to face the developer movement space where the transport path by the collection chamber transport member 303 and the transport path by the supply chamber transport member 302 are connected. .

  Since the distance from the planar pattern coil 11 to the developer moving space affects the detection accuracy of the magnetic permeability sensor 10, it is preferable to make it as short as possible. On the other hand, in the case of the embodiment shown in FIG. 8, the distance from the planar pattern coil 11 to the developer movement space is at least the total value of the thickness L of the casing 301 and the thickness of the double-sided tape or the like used as the adhesive layer 312. Become.

  As a member such as a double-sided tape used as the adhesive layer 312, it is preferable to use a generally distributed member from the viewpoint of cost, and the thinness is limited in that respect. On the other hand, the thickness L of the casing 301 needs to be maintained at a predetermined thickness in consideration of injection of a molding material into the mold during molding such as injection molding using a mold. Therefore, in the embodiment shown in FIG. 8, there is a limit to shortening the distance from the planar pattern coil 11 to the developer movement space.

  On the other hand, in the developing device 112 according to the present embodiment, the above-described problem is solved by providing an opening at a portion where the planar pattern coil 11 faces at the sensor attachment position 310. FIG. 9 is a diagram showing an attachment mode of the magnetic permeability sensor 10 at the sensor attachment position 310 according to the present embodiment.

  As shown in FIG. 9, at the sensor mounting position 310, an opening 313 is provided in a portion where the planar pattern coil 11 faces, that is, a portion facing the developer movement space. The opening 313 is a hole in a direction perpendicular to the surface to which the magnetic permeability sensor 10 is attached in the sensor attachment portion 310. Through the opening 313, the inside and the outside of the casing 301, which is a housing, are connected as a space. Thus, the distance from the planar pattern coil 11 to the developer movement space is only the thickness of the adhesive layer for attaching the magnetic permeability sensor 10 to the casing 301, excluding the thickness L of the casing 301.

  Here, the adhesive layer according to the present embodiment has a special structure for adhering the magnetic permeability sensor 10 to the opening 313 at the sensor attachment position 310 and thereby closing the opening 313. As shown in FIG. 9, the adhesive layer according to the present embodiment includes three layers, ie, a magnetic permeability sensor side adhesive layer 312a, a PET (Polyethylene Terephthalate) layer 314, and a casing side adhesive layer 312b.

  The PET layer 314 and the magnetic permeability sensor 10 are bonded by the magnetic permeability sensor side adhesive layer 312a. Then, the PET layer 314 and the sensor attachment part 310 of the casing 301 are bonded by the casing side adhesive layer 312b. That is, the PET layer 314 is used as an intermediate layer. Of the casing-side adhesive layer 312b, a portion corresponding to the planar pattern coil 11, that is, a portion corresponding to the opening 313 is provided with a notch as shown in FIG. As a result, it is possible to prevent the surface having adhesive force from being exposed to the opening 313 and sticking the developer to that portion.

  According to such a configuration, the planar pattern coil 11 faces the developer movement space via the magnetic permeability sensor side adhesive layer 312a and the PET layer 314. That is, the distance from the planar pattern coil 11 to the developer movement space does not need to consider the thickness L of the casing 301, and is only the thickness of the magnetic permeability sensor side adhesive layer 312a and the PET layer 314. The distance from the developer moving space to the developer moving space can be a short distance that can sufficiently secure the detection accuracy of the magnetic permeability sensor 10.

  As described above, in the developing device 112 according to the present embodiment, as a sensor for detecting the toner concentration in the developer housed inside, the magnetic flux in the space opposed by the coil formed as a planar pattern is used. Use a sensor to detect. An opening 313 is provided at a portion of the housing of the developing device 112 where the coil faces at a position where the sensor is attached.

  For this reason, the distance between the space for detecting the toner density and the coil is only the adhesive layer for attaching the sensor to the casing. In addition, since the thickness of the housing does not contribute to the distance between the space where the toner density is detected and the coil, it is not necessary to reduce the thickness of the housing, and it is necessary to adopt a thin housing with low productivity. Absent. Therefore, in the developing device that detects the concentration of the developer housed in the interior using a coil formed in a flat shape, the detection accuracy of the developer housed in the interior without reducing the productivity of the housing. Can be improved.

  In the above embodiment, the case where an adhesive layer having a three-layer structure as shown in FIG. 9 is used has been described as an example. However, when the replacement life of the developing device 112 is short and the sticking of the developer to the adhesive layer in the opening 313 does not become a problem or the development characteristics are not affected in the first place, the same adhesive layer as in FIG. 8 is used. Also good. In addition, a simple adhesive layer such as a double-sided tape may use a double-sided tape or the like having a resin base layer when there is a concern about strength and adhesive strength.

  Moreover, in the said embodiment, although the case where the PET layer 314 was used as a member for plugging the opening part 313 was demonstrated as an example, this is an example and if it is a nonmagnetic substance which does not have electroconductivity, The material can also be applied.

  Moreover, in the said embodiment, as shown in FIG. 9, the case where the opening part 313 was simply provided in the part which the planar pattern coil 11 opposes in the sensor attachment part 310 was demonstrated as an example. In addition to providing the opening 313, a tapered portion 313a may be provided in the opening 313 as shown in FIG. As shown in FIG. 11, the tapered portion 313 a connects the inner wall surface of the opening 313 that is a hole and the inner wall surface of the casing 301 that is a housing by an inclination.

  FIG. 12A is a diagram illustrating the flow of the developer conveyed by the collection chamber conveying member 303 with arrows in the case of the example of FIG. As shown in FIG. 12A, when the opening 313 is not tapered, there is a possibility that the developer does not flow through the opening and the developer stays in the opening.

  On the other hand, FIG. 12B is a diagram showing the flow of the developer in the case of FIG. As shown in FIG. 12B, by providing the tapered portion 313b, the flow of the developer conveyed by the collection chamber conveying member 303 passes through the opening portion, and the developer stays in the opening portion as described above. Can be prevented.

DESCRIPTION OF SYMBOLS 10 Magnetic permeability sensor 11 Planar pattern coil 12 Pattern resistance 13 1st capacitor 14 2nd capacitor 15 Feedback resistance 16, 17 Unbuffer IC
18 Output terminal 101 Paper feed tray 102 Paper feed roller 103 Registration roller 104 Paper 105 Conveying belt 106K, 106C, 106M, 106Y Image forming unit 107 Drive roller 108 Driven roller 109K, 109C, 109M, 109Y Photosensitive drum 110K Charger 111 Light Writing device 112K, 112C, 112M, 112Y Developer 113K, 113C, 113M, 113Y Photoconductor cleaner 115K, 115C, 115M, 115Y Transfer device 116 Fixing device 301 Casing 302 Supply chamber conveying member 303 Collection chamber conveying member 304 Developing roller 305 Flowing in Preventing wall 306 Partition plate 307 Developer regulating member 310 Sensor mounting portion 311 Supply port 312 Adhesive layer 312a Magnetic permeability sensor side adhesive layer 312b Casing side adhesive 313 opening 313a tapered portion 314 PET layer

JP 2010-26031 A

Claims (4)

A developing device in which a developer is conveyed by a magnetic substance inside a housing,
A magnetic permeability detector that outputs a signal having a frequency corresponding to the magnetic permeability inside the housing;
Including a mounting portion to which a magnetic permeability detector is mounted on the outer wall surface of the housing,
The magnetic permeability detector includes a coil that is formed in a planar pattern on a substrate and has an inductance that changes due to a change in the magnetic permeability inside the housing. The coil is in a space in the housing where the magnetic permeability should be detected. It is attached to the mounting part so as to oppose,
The attachment portion is provided with an opening so that the inside and outside of the housing are connected as a space at a portion where the coil is opposed in a state where the magnetic permeability detector is attached,
The developing device according to claim 1, wherein the opening is closed by attaching the magnetic permeability detector to the attachment portion.   The developing device according to claim 1, wherein the magnetic permeability detector is attached to the attachment portion via an adhesive layer formed of a nonmagnetic material having no conductivity. The adhesive layer is
An intermediate layer formed of a nonmagnetic material having no electrical conductivity;
A first adhesive layer that bonds the intermediate layer and the magnetic permeability detector;
A second adhesive layer that bonds the intermediate layer and the attachment portion;
The developing device according to claim 2, wherein the second adhesive layer exhibits an adhesive force while avoiding a portion facing the opening. The opening is a hole in a direction perpendicular to a surface to which the magnetic permeability detector is attached in the attachment portion;
The developing device according to claim 1, further comprising a tapered portion that connects the inner wall surface of the hole and the wall surface inside the housing with an inclination.