JP2006243259A - Development apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a satisfactory image free of density unevenness even if image formation is rapidly restarted after replenishment of a developer in a development apparatus for visualizing an electrostatic latent image by transferring the developer thereto. <P>SOLUTION: The developer remaining in a developer housing chamber 43 when replenished with the developer from a developer replenishing box 47 is detected. Before the development operation is started next, the stirring of the developer is performed by driving a developer agitating member 44 until the time of the duration corresponding to detected amount of the developer elapses. The detection of the residual amount of the developer is performed by counting the number of pixels of the image subjected to development from the time when the deposition of the developer is no more detectable by a developer detecting sensor 45, and estimating the amount corresponding to the count value from the amount of the developer when the developer detecting sensor 45 turns to a non-detection state. The agitating time is set long when the amount of the remaining developer is large and is short when the amount is small. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing device that is used in an image forming apparatus such as an electrophotographic system or an electrostatic recording system, and visualizes by attaching a powdery developer to an electrostatic latent image, and particularly uses a one-component developer. The present invention relates to a developing device.

  As a developing device using a one-component developer, for example, one having a configuration as described in Patent Document 1 has been widely known. As shown in FIG. 11, the developing device includes a developer carrier 103 at a position facing the image carrier 102 on which the electrostatic latent image is formed. The developer carrier 103 is arranged around the axis. A rotatable cylindrical sleeve and a magnet roll provided with a plurality of magnetic poles in the circumferential direction are provided inside the cylindrical sleeve. The magnet roll is supported so that the position of the magnetic pole is fixed. The developer is adsorbed on the surface of the cylindrical sleeve, and the developer is driven to the portion facing the image carrier 102 by the rotational driving of the cylindrical sleeve. It is intended to be transported. A developing bias voltage is applied between the cylindrical sleeve and the image carrier 102, and the one-component developer having a charge is image-bearing in an electric field formed in a region where the two are close and opposite to each other. Transfer to the electrostatic latent image on the body 102.

  The housing 101 that accommodates the developer carrier 103 is open on the front side where the developer carrier 103 faces the electrostatic latent image carrier 102, and the developer accommodating chamber 105 that accommodates the developer behind. It has. A developer agitation member 106 is provided in the developer storage chamber 105 to carry the developer and supply it to the developer carrier 103 while rotating and agitating. In addition, a developer regulating member 104 is provided in the housing so as to be in pressure contact with the developer carrying member, and the amount of adhesion is regulated by rubbing the developer adsorbed on the surface of the developer carrying member 103 to reduce the amount of adhesion. In addition to layering, the developer is charged by friction.

  A developer detection sensor is provided in the developer storage chamber 105 to detect when the developer T to be stored is supplied to the developer carrier 103 and is consumed by development and the remaining amount is low. When the developer detection sensor detects that the remaining amount of the developer is low, a warning to that effect is issued and the operator replenishes the developer. As for the replenishment of the developer, a method of replenishing the developer from the toner cartridge to the developer accommodating chamber, a replacement of the entire housing for accommodating the developer carrier, etc. A method of mounting the device is widespread.

  In general, in a large image forming apparatus, that is, an apparatus that forms an image on a large recording sheet such as A0 size or A1 size, the image carrier and the developer storage chamber are also large. Replacing is expensive and requires a lot of money. Therefore, a large-scale apparatus often employs a method of supplying the developer to the developer storage chamber when the developer remaining amount is low.

Further, as a method for detecting that the remaining amount of the developer has decreased, Patent Document 2 describes the number of pixels in which the developer has been transferred from the digitally processed image information for the developed image. An apparatus for estimating the residual amount of developer using the amount corresponding to the count value as the amount used is disclosed.
Japanese Patent Laid-Open No. 5-107910 JP-A-9-274369

However, the developing device that replenishes the developer storage chamber has the following problems.
The developer in the developer storage chamber is supplied to the developer carrier 103 by the developer agitating member 106, is made into a thin layer by the developer regulating member 104, and is transported to the development area. The developer that has not contributed to the development is returned again to the developer storage chamber 105 as the developer carrier 103 rotates. Thus, when the developer T is attracted to the surface of the developer carrying member 103 and repeatedly conveyed to the developing region, the developer T is rubbed against the developer regulating member 104 many times and receives a lot of load. For this reason, a phenomenon occurs in which an external additive (silica or the like) added to the developer for adjusting the charge amount is embedded in the toner or separated from the toner. The developer in which such an abnormality has occurred is not easily transferred to the electrostatic latent image at a position facing the image carrier 102 because the charging function is impaired and the charged charge is small. For this reason, the developer containing the charging failure gradually increases in the developer storage chamber 105. When the remaining amount of developer in the developer storage chamber becomes small, a large amount of developer having an abnormality in the charged state is contained.

  When a new developer is replenished in such a state, the charge amount becomes inhomogeneous between the developer under load and the newly replenished developer, resulting in uneven density in the developed recorded image. In particular, at both ends in the width direction of the image, the amount of the image to be developed is small, and the opportunity for the developer to fly to the image carrier is extremely small. For this reason, the image density is liable to be lowered or uneven in density at the edge part from the center part in the width direction of the image.

  The present invention has been made in view of the circumstances as described above, and the object thereof is to form a good image without unevenness in density, which can be promptly resumed after supplying the developer. It is.

  In order to solve the above-mentioned problems, the invention according to claim 1 is arranged to face an image carrier on which a latent image due to a difference in electrostatic potential is formed, and attaches a one-component developer to an endless peripheral surface. A developer carrying body to be conveyed, a developer carrying chamber in which the developer carrying body is provided in a direction opposite to the image carrying body and containing the one-component developer, and in the developer containing chamber A developer agitating member for agitating the one-component developer; and a developer replenishing device for replenishing the developer containing chamber with a new one-component developer, wherein the developer is replenished from the developer replenishing device. The developer amount remaining in the developer storage chamber at the time is detected, and the development is continued until a length of time corresponding to the detected developer amount elapses before starting the next development operation. It is set to drive the developer stirring member and stir the developer. To provide a developing device according to symptoms.

  In this developing device, after a new developer is replenished to the developer storage chamber, the remaining developer and the replenished new developer are sufficiently supplied until the next developing operation is started. Since the agitation is performed, development without unevenness of density can be performed from the beginning after the development operation is resumed. The time required for stirring to such an extent that uneven density is eliminated varies depending on the developer remaining in the developer storage chamber, but the stirring time is detected by detecting the residual amount of developer. Since the length corresponding to the developer amount is set, development without unevenness in density is possible regardless of the remaining amount of developer.

  According to a second aspect of the present invention, in the developing device according to the first aspect, the developer amount remaining in the developer accommodating chamber is detected by a developer detection sensor attached to a wall surface of the developer accommodating chamber. The developer accumulation is detected by the above, and the number of pixels of the developed image is counted from when the developer detection sensor enters the developer non-detection state, and an amount corresponding to the count value of the number of pixels is This is performed by subtracting from the residual amount of developer when the developer non-detected state is detected in advance.

  In this developing device, it is possible to detect that the residual amount of developer has decreased by a developer detection sensor attached to the wall surface of the developer storage chamber. Then, the consumption amount from the time when the developer detection sensor can no longer detect the developer due to the decrease in the residual amount is estimated from the count value of the number of pixels. In general, estimating the amount of developer consumption from the number of developed pixels causes some error, and the error accumulates as the amount of consumption increases, but the estimated consumption after detecting a predetermined remaining amount by the developer detection sensor Since the amount is small, the error between the actual consumption and the estimated consumption is small. Accordingly, the residual amount of developer in the developer storage chamber can be accurately detected. As a result, it is possible to accurately set the stirring time corresponding to the residual amount of developer, eliminate the uneven density by sufficiently stirring, and set the stirring time short without stirring longer than necessary. .

    According to a third aspect of the present invention, in the developing device according to the first or second aspect, the developing operation is performed when the detected amount of the developer remaining in the developer containing chamber is large when the developer is replenished. Before starting, the developer stirring member is driven to lengthen the time for stirring the developer, and when the detected value is small, the stirring time is shortened.

If the residual amount of developer at the time of replenishment of developer is small, the developer is sufficiently stirred in a short time. Is required.
In this developing device, when the residual amount of developer is small, the stirring time can be set short, and the developing operation can be restarted quickly, thereby shortening the waiting time for the operator. In addition, when there is a large amount of developer remaining, it is set so that stirring is performed for a sufficient period of time, and uneven density can be eliminated.

  According to a fourth aspect of the present invention, in the developing device according to the first aspect, after the supply of the one-component developer, the driving of the developer carrier is stopped until the next development operation is started. .

  In this developing device, the driving of the developer carrying member can be stopped until the next developing operation after the new developer is replenished, and the load of the developer by the developer regulating member can be reduced.

  According to a fifth aspect of the present invention, in the developing device according to any one of the first to fourth aspects, the developer stirring member is arranged around an axis parallel to the width direction of the peripheral surface of the developer carrier. The plate is driven to rotate, and is supported in parallel at a position apart from the axis, and has a plate that extends over substantially the entire width direction of the developer carrier, and the plate includes a bottom surface of the developer storage chamber and It shall move along the inner wall surface.

  In this developing device, stirring is efficiently performed by the plate of the developer stirring member, and the developer can be efficiently supplied to the developer carrying member.

  As described above, in the developing device of the present invention, after the developer is replenished, the developer replenished in the developer storage chamber and the remaining developer are agitated until the next developing operation is performed. The stirring time can be set to a time required to eliminate the uneven density. Therefore, the developer can be sufficiently stirred and good development can be performed from the first image after the developer is replenished. Further, the stirring time can be set to a short time as long as it is necessary to eliminate the uneven density, and the developing operation can be restarted promptly after the developer is replenished.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an image forming apparatus including a fixing device according to an embodiment of the present invention.
The image forming apparatus includes an image carrier 1 on which a latent image is formed on the surface by irradiation with image light after uniform charging, and the surface of the image carrier 1 is provided around the image carrier 1. A charging device 2 for uniformly charging, an exposure device 3 for irradiating the image carrier 1 with image light to form a latent image on the surface, and a one-component developer (hereinafter referred to as toner) on the latent image on the image carrier. ) Are selectively transferred to form a toner image, a transfer roller 5 that faces the image carrier 1 and generates a transfer bias electric field between the image carrier and a recording sheet, and toner A cleaning device 6 is provided for removing toner remaining on the image carrier 1 after image transfer. A conveyance path 7 for supplying a recording sheet is formed from the upstream side of the facing portion between the image carrier 1 and the transfer roll 5, and an unfixed toner image transferred onto the recording sheet is heated and melted on the downstream side. Then, a fixing device (not shown) for pressing the recording sheet is provided.

  In this image forming apparatus, it is necessary to open a recording sheet conveyance path in order to remove a recording sheet jammed during conveyance and for maintenance and inspection of the apparatus. For this reason, as shown in FIG. 2, the member provided above the conveyance path jumps upward together with the support frame 8 to open the conveyance path.

  As the image carrier 1, a metal drum surface having a photosensitive layer made of an organic photosensitive material, an amorphous selenium photosensitive material, an amorphous silicon photosensitive material, or the like can be used. This image forming apparatus is capable of forming an image on a large size recording sheet such as A0 or A1, and the peripheral surface of the image carrier has a width corresponding thereto.

  The charging device 2 is formed by coating a metal roll having conductivity such as stainless steel or aluminum with a coating of a high resistance material. The charging device 2 is in contact with the image carrier 1 and is driven to rotate. Then, when a predetermined voltage is applied, a continuous discharge is generated in a minute gap near the contact portion between the roll and the image carrier 1, and the surface of the image carrier 1 is charged almost uniformly. It is.

  As shown in FIG. 7, the roll 2 is configured such that three rolls 21a, 21b, and 21c are arranged in the width direction of the peripheral surface of the image carrier 1 to charge the entire width. This is to cope with the increase in the width of the peripheral surface of the image carrier in order to form an image on a large recording sheet. In other words, when one roll is brought into contact with the wide image carrier 1, the rigidity is small, so that bending is likely to occur, and smooth driven rotation may be hindered. It has become.

  As shown in FIG. 7, the rolls 21a, 21b, and 21c divided into three as described above are composed of two rolls 21a and 21c arranged at positions close to both side edges of the image carrier 1 as shown in FIG. It arrange | positions in the upstream in the circumferential direction of a surrounding surface, and the roll 21b of the center part is arrange | positioned in the downstream. The rolls 21a and 21c on both sides are supported with their axes shifted so that the end close to the side edge of the image carrier 1 is slightly downstream from the end on the center side.

The support shafts of these rolls 21a, 21b, and 21c are rotatably supported at both ends, and a stopper 22 is provided so as to contact the end surface so as not to move in the axial direction. When the roll 21 is provided in parallel with the axis of the image carrier 1, when the roll 21 is rotated by being driven by the image carrier 1, the position is deviated in any of the axial directions due to surface accuracy or the like, and the support shaft Comes into contact with the stopper 22. At the contact portion, the stopper or the support shaft is worn, and wear powder is generated. When the wear powder falls on the surface of the image carrier 1, it may come into contact with the surface of the roll 21b on the downstream side from the surface of the image carrier 1, and this portion may be poorly charged. In addition, the photosensitive layer may be scratched by the abrasion powder. In order to solve such problems, the two rolls 21 a and 21 c arranged near the side edges as described above are arranged with the axis slightly inclined with respect to the axis of the image carrier 1. There is a slight axial force to the outside of the rolls 21a, 21c by arranging as described above. As a result, the support shaft of the roll and the stopper 22 are not rubbed strongly in the image forming area on the peripheral surface of the image carrier 1.
With the above structure, even if the support shaft and the stopper come into contact with each other and wear powder is generated, the image on the image carrier is not affected.

  Further, in order to generate an axial force on the roll toward the side edge of the image carrier 1, as shown in FIG. 8, the force for pressing the roll against the image carrier on the center side is made larger than the position near the side edge. May be. Moreover, as shown in FIG. 9, you may make the diameter of a roll slightly large in the center side. By adopting such a configuration, it is possible to generate a force in the axial direction toward the outside on the support shafts of the two rolls 21a and 21c arranged at positions close to the side edges.

  At the ends of the three rolls 21a, 21b, and 21c arranged as described above, the adjacent rolls are arranged so that a small portion wraps and comes into contact with the peripheral surface of the image carrier. As a result, the peripheral surface of the image carrier is charged without a gap even if the charging roll is divided. However, as described above, at the portion where the contact area of the two rolls wraps, discharge occurs between both rolls. For this reason, the surface energy of the photoreceptor formed on the surface of the image carrier increases, and the friction coefficient increases. When the cleaning member is rubbed, film reduction or damage is likely to occur.

  In order to eliminate such inconvenience, in this image forming apparatus, the end portions of the rolls 21a, 21b, 21c arranged for charging the image carrier are side edges of the peripheral surface as shown in FIG. Is formed so as to vary in the axial direction. When the two adjacent rolls 21a and 21b and the image carrier 1 are in contact with each other when rotating in synchronization with the adjacent rolls, the edges of the range where the image carrier 1 is in contact with each other are overlapped by the same width. It swings in the direction. As a result, the range in which the charging region is wrapped by the two rolls 21a and 21b is not limited to the narrow range in the axial direction, but is distributed over a wide width. This suppresses film thickness reduction or damage of the photoreceptor layer.

In the exposure apparatus 3, light emitting elements that blink on the basis of digital image signals are arranged in the width direction of the peripheral surface of the image carrier 1, and the light emitted from each light emitting element is transmitted to the periphery of the image carrier 1. Irradiate the surface. In the portion irradiated with the emitted light, the electrostatic potential on the surface of the image carrier 1 is attenuated, and a latent image is formed due to the difference in potential.
The blinking control of the light emitting element is performed by the exposure control device 31, which counts the number of pixels to be exposed and stores the accumulated value.

  The developing device 4 contains black toner, and transfers the toner to a latent image on the image carrier at a position close to and facing the image carrier 1 to form a visible image. Details of the configuration will be described later.

  The transfer roll 5 is formed by coating a core metal with an elastic material having a medium resistance. By applying a transfer bias voltage between the transfer roll 5 and the image carrier 1, a toner image on the image carrier 1 is recorded on a recording sheet. Is to be transferred to. As shown in FIG. 1, the transfer roll 5 is supported by a support frame 51 fixedly supported on the main body of the image forming apparatus so as to be able to advance and retreat with respect to the image carrier 1. It is pressed to the side. A recording sheet is fed into a nip portion between the image carrier 1 and the recording sheet that has passed through the nip portion is conveyed along a guide member 53 provided on the downstream side.

  The guide member 53 is supported by a rotation frame 54 mounted on the support shaft 5a of the transfer roll 5, and is supported so that the relative position with respect to the rotation center of the transfer roll 5 does not fluctuate. That is, the rotation frame 54 can be rotated with respect to the support shaft 5 a of the transfer roll 5, and when the transfer roll 5 advances and retreats with respect to the image carrier 1, the rotation frame 54 is Although it rotates with the movement of the support shaft 5a of the transfer roll, the distance between the guide member 53 supported by this and the peripheral surface of the transfer roll 5 does not change. The rotating frame 54 is brought into contact with a support frame 51 whose lower end portion is fixedly supported, the position thereof is restricted, and the support is provided by a plate-like member 55 of a conveyance guide provided on the downstream side of the transfer roll 5. The frame 51 is pressed against and supported.

With the structure as described above, the gap between the surface of the transfer roll 5 and the guide member 53 is always constant even if there is some variation in the amount of elastic deformation of the frame body 8 and the transfer roll 5 that support the image carrier 1. This prevents the recording sheet from entering the gap and causing a paper jam.
In the case of using a large recording sheet like this image forming apparatus, the recording sheet is wound up in a roll shape and has a curl. For this reason, even a slight change in the position of the guide member 53 tends to cause a paper jam. As shown in FIG. 2, it is difficult for the frame body 8 that rotates so as to open the conveyance path to maintain high accuracy, and some error occurs in the position of the image carrier 1. Further, if there is a variation in the position of the transfer roll 5 or the amount of elastic deformation of the transfer roll, and the guide member 53 is supported at the same position relative to the body of the image forming apparatus, the transfer roll 5 and the guide member 53 The gap fluctuates and paper jam is likely to occur. Such a problem is solved by the above structure.

  The cleaning device 6 presses a blade against the surface of the image carrier 1 and removes the toner remaining on the image carrier so as to be scraped off. Further, instead of the blade, the toner may be scraped off by a roll member or the toner may be swept out by a brush.

  The fixing device includes a fixing roll having a heating unit and a pressure roll. A recording sheet carrying an unfixed toner image is sandwiched between the fixing roll and the pressure roll and heated and pressed to record the toner image. The image is fused to a sheet to form a fixed image.

Next, the configuration and function of the developing device used in the image forming apparatus, which is an embodiment of the present invention, will be described.
FIG. 3 is a transverse sectional view of the developing device 4, and FIG. 4 is a plan sectional view.
This developing device includes a developer carrier 41 that adsorbs and conveys developer on the surface, and is supported by a portion where the housing 42 is opened, and is supported so as to be close to and face the image carrier 1. . A developer storage chamber 43 is provided in the housing 42 at a position adjacent to the developer carrier 41, and the developer is supplied to the developer carrier 41 and stirred in the developer storage chamber 43. A developer agitating member 44 and a developer detection sensor 45 that detects when the remaining amount of the developer is low are provided. Further, a developer regulating member 46 that regulates the amount of developer attached is pressed against the developer carrier 41. A developer replenishment box 47 can be mounted above the developer accommodating chamber 43, and the developer is dropped into the developer accommodating chamber 43 and replenished as indicated by an arrow A in FIG. It has become something that can be.
The driving of the developer carrier 41 and the developer agitating member 44 is controlled by a drive control device 48. The driving during the developing operation is controlled and the developer is supplied from the developer supply box 47. It controls the subsequent drive.

  The developer carrier 41 includes a cylindrical sleeve 41a that is disposed so as to be close to and opposed to the image carrier 1 and is rotationally driven, and a substantially cylindrical magnet roll 41b that is fixedly supported on the inside thereof. It is. The cylindrical sleeve 41 a is a thin member made of a metal such as aluminum, and a developing bias voltage is applied between the cylindrical sleeve 41 a and the image carrier 1. A plurality of S poles and N poles are alternately provided along the circumference of the magnet roll 41b, and the magnet roll 41b is fixedly supported, so that the position of the magnetic pole is not moved. The arrangement of these magnetic poles forms a magnetic field that attracts the developer along the surface of the cylindrical sleeve 41b, and conveys the developer adsorbed on the peripheral surface by the circular drive of the cylindrical sleeve 41a. Can be done.

  The developer regulating member 46 has a soft elastic body 46 b in pressure contact with the surface of the developer carrying body 41 in the vicinity of the other end of the leaf spring 46 a having one end fixed to the housing 42. By this soft elastic body 46b, the developer magnetically adsorbed on the surface of the developer carrying member is thinned and a charge is given to the developer by friction.

  The developer accommodating chamber 43 is provided substantially along the axial direction of the developer carrier 41 and agitates the developer accommodated by the rotation of the developer agitating member 44.

  The developer agitating member 44 has a rotation shaft 44a parallel to the axial direction of the developer carrier 41, and the plate 44b mounted at a position eccentric to the rotation center of the rotation shaft rotates to agitate the developer. Then, the developer is pushed out and supplied to the developer carrier 41 side. The rotating shaft 44a and the plate 44b are made of nonmagnetic stainless steel.

  Further, a developer detection sensor 45 is attached below the wall portion in the developer storage chamber 43. This developer detection sensor 45 detects the developer magnetism to detect the presence or absence of developer deposition. When the developer remaining amount is small and developer deposition cannot be detected, A signal to that effect is output, and a display indicating that the developer needs to be supplied is displayed on a display panel or the like (not shown). The amount of developer remaining in the developer storage chamber 43 when the signal from the developer detection sensor 45 is output is known by experiments and the like.

  The developer replenishment box 47 is attached to the upper portion of the developer storage chamber 43 after a display indicating that the residual amount of the developer is reduced by a signal from the developer detection sensor 45, and a new developer is loaded. This is supplied to the developer storage chamber 43. When the developer supply box 47 is mounted, a predetermined signal is output, and the shutter of the developer supply box 47 and the supply port of the developer storage chamber 43 are opened by this signal to supply the developer.

  In such a developing device, when the developer is consumed by repeatedly performing the developing operation, the amount of accumulation in the developer accommodating chamber 43 decreases. Since the developer has fluidity, the developer has almost the same depth in the developer storage chamber 43. When the predetermined depth is reached, the developer detection sensor 45 attached to the wall of the developer storage chamber 43 develops. Agent accumulation is no longer detected. That is, from this point of time, the developer detection sensor 45 enters a developer non-detection state. At the same time, a notification indicating that it is time to replenish the developer is displayed on the display panel. Further, the exposure control device 31 counts the number of pixels in the development portion of the image output after the developer detection sensor 45 is in the non-detection state, and the accumulated value is stored.

  When the developer supply box 47 is mounted and the developer is supplied, the amount of toner used is estimated based on the cumulative value counted at that time. That is, the amount of developer consumed after the developer detection sensor 45 is in a developer non-detection state is estimated from the number of pixels to be developed. Therefore, the residual amount of developer at the time of developer replenishment is calculated by further subtracting the subsequent consumption amount from the previously known developer residual amount when the developer detection sensor 45 is in the non-detection state. Is done.

  Estimating the consumption amount of the developer from the number of pixels to be developed as described above causes a slight error, but the consumption amount is calculated based on the accumulated value after the developer detection sensor 45 is in the non-detection state of the developer. The estimated value is relatively small. For this reason, the error which arises is also small and the residual amount of developer can be estimated accurately.

  In the drive control device 48, the relationship between the amount of developer remaining in the developer storage chamber 43 and the time for stirring after the developer is replenished until the next developing operation is started is set in advance. The time for stirring is set from the calculated residual amount of developer. The developer stirring member 44 performs the stirring operation until the set time elapses, and then restarts the developing operation. Therefore, the remaining developer and the replenished new developer are sufficiently stirred, and good development without unevenness in density is performed from the time of restart.

  The table for setting the stirring time, that is, the relationship between the amount of developer remaining in the developer accommodating chamber 43 and the time for stirring after the developer replenishment until the next developing operation is started, is as follows, for example. Can be set to

  Let Ag be the residual amount of developer when the developer detection sensor 45 provided in the developer storage chamber 43 is in a non-detection state of the developer. This value varies depending on the mounting position of the developer detection sensor, and is measured in advance by experiment. Then, when a new developer is replenished in this state, the stirring time that can eliminate unevenness in the density of the developed image is investigated by experiment. Let this stirring time be B seconds. The amount of developer to be replenished at one time is determined, and is determined by the capacity of the developer replenishment box 47 (toner cartridge) mounted on the upper portion of the developer storage chamber 43.

  On the other hand, it has been found that when the residual amount of the developer is reduced, the density unevenness can be eliminated even if the stirring time is set short, and the amount of the developer that does not cause the density unevenness without stirring is examined by experiment. The residual amount of developer at this time is Cg. From these relationships, as shown in FIG. 5, the stirring time set in the range where the residual amount of developer is from Ag to Cg can be set between 0 seconds and B seconds. Between these, it may be set as a straight line as shown in FIG. 5, but the stirring time during which the uneven density is eliminated is measured by experiment between Ag and Cg, and the curve is shown in FIG. It can also be complemented and set more accurately.

  The stirring time set as described above is started after the developer supply is completely completed. As means for notifying that replenishment has been completed, for example, a sensor installed at the junction with the developer replenishment box 47 to detect that the cartridge has come off can be employed.

  At the time of agitation, it is preferable to stop the driving of the developer carrier 41 and reduce the developer load by the developer regulating member 46. When the developer carrier 41 and the developer regulating member 46 are driven by the same drive source, a clutch is provided in the gear for driving the developer carrier 41, and the developer carrier is agitated after toner replenishment. The drive of 41 can be stopped.

  After replenishing the developer as described above, by performing agitation for an appropriate time in the developer storage chamber 43, when the development operation is resumed, it is possible to perform good development without uneven density from the first image. .

1 is a schematic configuration diagram illustrating an example of an image forming apparatus in which a developing device according to the present invention is used. FIG. 2 is a schematic configuration diagram illustrating a state where a recording sheet conveyance path is opened in the image forming apparatus illustrated in FIG. 1. 1 is a schematic configuration diagram of a developing device according to an embodiment of the present invention. FIG. 4 is a plan sectional view of the developing device shown in FIG. 3. FIG. 4 is a diagram illustrating a relationship between a residual amount of developer at the time of developer replenishment and an agitation time necessary after developer replenishment. FIG. 4 is a diagram illustrating a relationship between a residual amount of developer at the time of developer replenishment and an agitation time necessary after developer replenishment. FIG. 2 is a schematic diagram illustrating a configuration of a charging device used in the image forming apparatus illustrated in FIG. 1. FIG. 6 is a schematic diagram illustrating another example of a charging device that can be used in the image forming apparatus illustrated in FIG. 1. FIG. 6 is a schematic diagram illustrating another example of a charging device that can be used in the image forming apparatus illustrated in FIG. 1. FIG. 10 is a schematic diagram illustrating a configuration that can be employed at an end portion of a roll of the charging device illustrated in any of FIGS. 7 to 9. It is a schematic block diagram which shows the conventional developing device.

Explanation of symbols

1: image carrier, 2: charging device, 3: exposure device, 4: developing device, 5: transfer roll, 5a: support shaft of transfer roller, 6: cleaning device, 7: transport path, 8: frame 21: Roll used for charging device, 22: stopper, 31: exposure control device,
41: Developer carrying member, 41a: Cylindrical sleeve, 41b: Magnet roll, 42: Housing, 43: Developer storage chamber, 44: Developer stirring member, 44a: Rotating shaft, 44b: Plate, 45: Developer detection Sensor 46: developer regulating member 46a: leaf spring 46b: soft elastic body 47: developer supply box 48: drive control device
51: Support frame 52: Spring 53: Guide member 54: Rotating frame 55: Plate member

Claims (5)

A developer carrier disposed opposite to an image carrier on which a latent image due to a difference in electrostatic potential is formed, and carrying a one-component developer on an endless peripheral surface;
A developer containing chamber in which the developer carrying member is provided in a direction facing the image carrying member and contains the one-component developer;
A developer agitating member for agitating the one-component developer in the developer accommodating chamber;
A developer replenishing device that replenishes a new one-component developer into the developer accommodating chamber,
Detecting the amount of developer remaining in the developer storage chamber when the developer is supplied from the developer supply device;
Next, before starting the developing operation, the developer agitating member is driven to agitate the developer until a time corresponding to the detected amount of developer elapses. A developing device. Detection of the amount of developer remaining in the developer storage chamber,
While detecting developer deposition by a developer detection sensor attached to the wall surface of the developer storage chamber,
Count the number of pixels of the developed image from when the developer detection sensor is in the developer non-detection state,
The developing device according to claim 1, wherein the developing device is configured to subtract an amount corresponding to the count value of the number of pixels from a developer remaining amount when the developer non-detected state is detected in advance.   If the detected amount of developer remaining in the developer storage chamber is large when the developer is replenished, the developer agitating member is driven before the developing operation is started, and the time for stirring the developer is detected. 3. The developing device according to claim 1, wherein when the value is small, the stirring time is shortened.   2. The developing device according to claim 1, wherein after the supply of the one-component developer, the driving of the developer carrying member is stopped until the next developing operation is started. The developer stirring member is rotationally driven around an axis parallel to the width direction of the peripheral surface of the developer carrier,
A plate that is supported in parallel at a position away from the axis, and extends over substantially the entire width direction of the developer carrier,
5. The developing device according to claim 1, wherein the plate moves along a bottom surface and an inner wall surface of the developer storage chamber.

Images