JP2009031596A - Developing apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing apparatus and an image forming apparatus which can make the developing apparatus discharge developer by spring-up of a supply spring and replacing the developer in the apparatus, in a state of maintaining the amount of developer in the apparatus to be within a fixed range, even if the rotational speed of the supply screw is changed. <P>SOLUTION: The developing apparatus 4 has a control board 88, which is a screw rotating speed control means for controlling multiple kinds of setting of the rotating speed of the supply screw 8, at a copying machine 500 serving as the image forming apparatus. The control board 88 controls a solenoid 98 for adjusting the height of a discharge opening member 135, having a developer discharge port 94 that serves as a discharge opening part. The height of the developer discharge port 94 is thereby adjusted, according to the rotating speed of the supply screw 8. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing device used for a copying machine, a facsimile, a printer, and the like, and an image forming apparatus using the developing device.

  Conventionally, an image forming apparatus including a developing device using a two-component developer including toner and a magnetic carrier has been widely used. As an image forming apparatus of this type, the toner density of the developer is kept within a predetermined range by supplying toner from the toner container as necessary to the developer in the developing apparatus that consumes toner with development. There is something to keep in. In such a configuration, the carrier in the developer is hardly consumed and used repeatedly, and therefore the carrier deteriorates as the image is output. Specifically, the coating film on the carrier surface is scraped by mechanical stress or the toner component is spent on the carrier surface. When the carrier is deteriorated, the ability to charge the toner of the carrier is gradually reduced, causing problems such as background stains, image density reduction, abnormal image density unevenness and toner scattering. For this reason, in this type of image forming apparatus, a service person regularly visits the user to exchange carriers. For this reason, maintenance costs are incurred, and the unit price for image formation is high.

  Patent Document 1 discloses a developing device that discharges an increased amount of developer from the developing device while replenishing the developer in the developing device with a premix developer in which a carrier and toner are mixed to recover the toner concentration. Is described. In such a configuration, a new carrier in the premix developer is replenished to the developer in the developing device while the carrier that has become old due to the discharge of the developer is gradually discharged from the developing device. Then, the carrier replacement work can be omitted by replacing the carrier in the developer gradually with a new one by such discharge and replenishment.

  In the developing device described in Patent Document 1, the developer is supplied to the developing roller on the side wall on the downstream side of the position where the developer is supplied to the developing roller in the supply conveyance path that conveys the developer in the axial direction of the developing roller. The developer is discharged out of the developing device from the provided developer discharge port. A circulation opening that communicates with the circulation conveyance path that delivers the developer to the upstream end of the supply conveyance path is provided downstream of the position where the developer discharge port is provided. In this developing device, when the premix developer is supplied and the amount of developer in the developing device increases, the bulk of the developer in the supply conveyance path increases. At this time, at the position where the developer discharge port is provided, the developer reaching the height of the developer discharge port overflows from the developer discharge port, whereby the developer is discharged to the outside of the developing device, and the developer discharge port is provided. The developer that has not been discharged at the given position is sent to the circulation conveyance path through the circulation opening. Further, in the state where the volume of the developer in the supply conveyance path does not change, the developer does not reach the height of the developer discharge port at the developer discharge port, so the developer is not discharged, and the supply conveyance path The developer that reaches the downstream side of the toner is sent to the circulation conveyance path.

  In such a developing device, the increased amount of developer supplied by the premix developer is discharged from the developer discharge port, so that the carrier in the developer in the device is gradually replaced with a new one. Can continue. Further, since the developer is not discharged in a state where the volume of the developer in the supply conveyance path does not change, it is possible to prevent the developer amount in the developing device from decreasing.

  The developing device of Patent Document 1 includes a supply screw that imparts a conveyance force to the developer in the supply conveyance path, and even a necessary developer that is not excessive due to the jumping of the supply screw that faces the developer discharge port. Is also a problem. In order to solve such a problem, in Patent Document 1, the portion of the supply screw that faces the developer discharge port has a shape in which the developer is less likely to jump up than the other portions of the supply screw. Specifically, the outer diameter of the wing portion of the portion facing the developer discharge port is made smaller than the outer diameter of the wing portion of the other portion, or the wing portion is provided in the portion facing the developer discharge port. There is no shape.

JP 2000-112238 A

However, as a result of extensive research conducted by the present inventors, even if the developer is discharged from the developer discharge port using the jumping up of the supply screw, the developer is not discharged. I found out that
FIG. 12 shows the height of the developer surface of the developer (hereinafter referred to as “developer surface height”) and the height at which the developer that has been bounced up (hereinafter referred to as “bounce-up reach height”). ). From FIG. 12, it can be seen that the higher the developer surface height, the higher the jumping height.

The relationship between the developer surface height and the bounce-up arrival height will be described with reference to FIG. 13. FIG. 13 is an explanatory diagram of a mechanism that causes a difference in the jumping height due to a difference in developer surface height. FIG. 13A is an explanatory diagram in a state where the developer surface height is low, and FIG. 13B is an explanatory diagram in a state where the developer surface is high.
As shown in FIG. 13A, when the developer surface Tf of the developer T in the supply conveyance path 9 is low, the developer adhering to the supply screw 8 is jumped up in the direction of the developer discharge port 94. It moves in the direction of the rotation axis of the supply screw 8 by its own weight. For this reason, as indicated by the arrow in FIG. 13A, the length of the arm by which the developer is splashed up by the supply screw 8 is shortened and cannot be jumped up high.
On the other hand, as shown in FIG. 13B, when the developer surface Tf is high, the developer adhering to the supply screw 8 is splashed up without falling. For this reason, as shown by the arrow in FIG. 13B, the length of the arm by which the developer is splashed up by the supply screw 8 is increased, and the developer can be jumped up.

When the amount of developer in the developing device is less than the necessary amount, the state shown in FIG. 13A is obtained, and when the amount of developer exceeds the necessary amount, the state shown in FIG. 13B is obtained. , The height to be arranged, and the shape and rotation speed of the supply screw 8 are set.
By setting in this way, when the premix developer is supplied and the developer T increases, the state shown in FIG. 13B is reached, and the splashed developer reaches the developer discharge port 94 and increases. The developer T is discharged from the developer discharge port 94. As a result, the carrier in the developer in the developing device can be gradually replaced with a new one.
On the other hand, in the state where the developer amount does not increase and the developer amount is only a necessary amount as shown in FIG. 13A, the jumped-up developer does not reach the developer discharge port 94, so the supply screw 8 Therefore, it is possible to prevent the necessary developer from being discharged by jumping up.

However, the relationship between the developer surface height and the jump-up reach height is as shown in the graph of FIG. 12 when the rotation speed of the supply screw 8 is constant, and the developer is different if the rotation speed of the supply screw 8 is different. Even if the surface height is the same, the jumping height is different.
FIG. 14 is a graph showing the relationship between the number of rotations of the supply screw 8 and the jump-up reaching height when the developer surface height is constant. As shown in FIG. 14, the higher the number of revolutions of the supply screw 8 is, the higher the jumping height is reached, and the smaller the number of rotations of the supply screw 8 is, the lower the amount of jumping is reached. This is presumably because the higher the initial speed jumped up by the supply screw 8, the higher the jump.

In the image forming apparatus, the image forming speed may be slowed down (for example, half the normal time) when printing on thick paper.
At this time, the rotational speed of the supply screw 8 of the developing device is also reduced. In such a developing device, when the position of the developer discharge port 94 and the like are set in accordance with the rotation speed of the supply screw 8 at the normal time, the following problems occur. That is, when the image forming speed is slowed down, the developer splashed up by the supply screw 8 does not reach the developer discharge port 94, or even if it reaches, the reached amount is smaller than normal. In this case, the amount of the developer in the developing device increases, and there is a problem that the increased amount of developer is not discharged even if an excessive amount of developer is present beyond the necessary amount. If an excessive amount of developer is present in the developing device, the amount of developer in the supply conveyance path increases, and the excessive developer moves on the developing sleeve to cause density unevenness, or the developer is not in the developing device. It overflows from the casing and splashes into the device.

  On the other hand, if the position or the like of the developer discharge port 94 is set in accordance with the rotational speed of the supply screw 8 when the image forming speed is reduced, the following problems occur. That is, even when the developer amount is not increased at the normal rotation speed of the supply screw 8 (the state shown in FIG. 13A), the developer reaches the developer discharge port 94 that is flipped up by the supply screw 8. Resulting in. For this reason, even the necessary developer that is not excessive is discharged due to the jumping of the supply screw 8, and the required amount of developer in the developing device cannot be maintained. As a result, a necessary amount of developer cannot be supplied to the developing roller, and toner cannot be supplied to the electrostatic latent image on the photosensitive member, resulting in a problem that the image is missing.

  Such a problem is not limited to a developing device using a two-component developer. A developing device that uses a one-component developer as long as the developer is replenished by the developer replenishing means and the developer is configured to discharge the increased amount of developer in the developing device by the developer discharging means. It is also a problem that can occur.

  The present invention has been made in view of the above-described problems, and an object of the present invention is a developing device that discharges the developer by jumping up the supply screw. Even if the rotation speed of the supply screw is changed, the present invention is provided. It is an object of the present invention to provide a developing device capable of replacing the developer in the apparatus while maintaining the developer amount within a certain range, and an image forming apparatus including the developing device.

In order to achieve the above object, the invention according to claim 1 is characterized in that the developer is carried on the surface and rotated, and the toner is supplied to the latent image on the surface of the latent image carrier at a position facing the latent image carrier. A developer carrying member to be developed, a supply carrying path for carrying the developer along the axial direction of the developer carrying member while supplying the developer carrying member, a rotating shaft and a spiral blade A supply screw that applies a conveyance force to the developer in the supply conveyance path by rotating about the rotation axis, and a developer that has reached the downstream end in the conveyance direction of the supply conveyance path A circulation conveyance path that conveys to the upstream end in the conveyance direction of the supply conveyance path; and a circulation conveyance member that applies a conveyance force to the developer in the circulation conveyance path. In the developing device having a discharge opening for discharging in the supply conveyance path, the supply screw Screw rotation speed control means for controlling the rotation speed to a plurality of settings, and discharge lower end height adjustment means for adjusting the height of the lower end portion for discharging the developer at the discharge opening according to the rotation speed of the supply screw. It is characterized by having.
According to a second aspect of the present invention, in the developing device according to the first aspect, the discharge lower end height adjusting means adjusts the height of the position of the discharge opening in accordance with the rotational speed of the supply screw. A developing device which is a thickness adjusting means.
According to a third aspect of the present invention, in the developing device of the second aspect, the casing forming the supply conveyance path includes a casing opening that is a larger opening than the discharge opening at a position where the discharge opening is provided. And a shape in which the discharge opening is provided in the shielding member, and is arranged so as to be movable in a vertical direction to a position facing the casing opening, and the casing opening other than the region facing the discharge opening Based on the setting of the rotation speed of the supply screw by the discharge opening member lifting / lowering means for moving the discharge opening member in the vertical direction as the opening position height adjusting means, and the screw rotation speed control means. And a discharge opening member lifting / lowering control means for controlling the discharge opening member lifting / lowering means.
According to a fourth aspect of the present invention, in the developing device of the first aspect, the discharge lower end height adjusting means has a substantial opening width through which the developer in the discharge opening can pass according to the rotational speed of the supply screw. A developing device which is a substantial opening width lower end adjusting means for adjusting a lower end.
According to a fifth aspect of the present invention, in the developing device of the fourth aspect, as the substantial opening width lower end adjusting means, the supply screw at the same position as the discharge opening in the developer conveyance direction in the supply conveyance path is the above-mentioned. A shutter member which is arranged on the outer peripheral side of the wing portion so as to be rotatable about the axis of the rotation shaft and which blocks a part of a space between the supply screw and the discharge opening by rotating; and the supply screw A screw rotational force transmitting means for transmitting a force in the rotational direction to the shutter member, and a shutter urging member for urging the shutter member to rotate in a direction opposite to the rotational direction of the supply screw, The screw rotational force transmitting means is such that the higher the rotational speed of the supply screw, the stronger the force that rotates the shutter member in the rotational direction of the supply screw. When the force for rotating the shutter member becomes larger than the force for urging the shutter member of the shutter urging member, the shutter member rotates in the rotation direction of the supply screw, and the shutter member becomes the discharge opening. The substantial opening width is narrowed by blocking the space between the lower part of the screw and the supply screw, and the force for rotating the shutter member of the screw rotational force transmitting means urges the shutter member of the shutter urging member. When the force is smaller than the force, the shutter member rotated in the rotation direction of the supply screw rotates in the direction opposite to the rotation direction of the supply screw by the biasing of the shutter biasing member, and the lower portion of the discharge opening The substantial opening width is widened by opening a portion blocked by the shutter member in a space between the supply screw and the supply screw.
According to a sixth aspect of the present invention, in the developing device of the fifth aspect, the screw rotational force transmitting means is rotated by rotation of a flange provided on the shutter member and the supply screw to press the flange. The flange portion is arranged at a position always in contact with the developer in the supply conveyance path on the outer peripheral side of the blade portion of the supply screw, and rotates when the supply screw rotates. The developer is pressed in the rotation direction of the supply screw, and transmits a force in the rotation direction of the supply screw to the shutter member.
According to a seventh aspect of the present invention, in the developing device according to the fifth aspect, the screw rotational force transmitting means includes a cylindrical guide member provided at both ends of the shutter member in the axial direction of the rotation shaft, and the guide. A rubbing member that rubs the inner peripheral surface of the member, and the rubbing member is attached to the supply screw through a biasing member, and the outer peripheral direction of the supply screw is caused by centrifugal force generated by the rotation of the supply screw. And the tip of the guide member contacts the inner peripheral surface of the guide member and rubs.
The invention of claim 8 is the developing device according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the lower end of the discharge opening is positioned higher than the upper end of the supply screw. A discharge opening is provided.
According to a ninth aspect of the present invention, at least a latent image carrier, a charging means for charging the surface of the latent image carrier, and formation of a latent image for forming an electrostatic latent image on the latent image carrier. In the image forming apparatus having a developing means for developing the electrostatic latent image into a toner image, the developing means is defined as claim 1, 2, 3, 4, 5, 6, 7 or 8. The developing device described in 1) is used.

  In the first to ninth aspects of the invention, the height of the lower end portion for discharging the developer in the discharge opening is adjusted by the discharge lower end height adjusting means in accordance with the rotational speed of the supply screw. That is, when the rotation speed of the supply screw is fast, the height of the lower end portion for discharging the developer at the discharge opening is adjusted to be high, and when the rotation speed is slow, the height of the lower end portion is lowered. Adjust. As a result, the required amount of developer in the developing device can be maintained even when the rotation speed of the supply screw is high, and the developer amount in the developing device is prevented from becoming excessive even when the rotation speed is slow. Can do.

  According to the first to ninth aspects of the present invention, the required amount of the developer in the developing device can be maintained even when the rotation speed of the supply screw is changed, and the developer amount can be prevented from becoming excessive. There is an excellent effect that the developer in the apparatus can be replaced while the developer amount in the apparatus is kept within a certain range.

Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment of a tandem type color laser copier (hereinafter simply referred to as “copier 500”) in which a plurality of photoconductors 1 are arranged in parallel will be described.
FIG. 2 is a schematic configuration diagram of the copier 500 according to the present embodiment. The copier 500 includes a printer unit 100, a paper feeding device 200 on which the printer unit 100 is placed, a scanner 300 fixed on the printer unit 100, and the like. An automatic document feeder 400 fixed on the scanner 300 is also provided.

  The printer unit 100 includes an image forming unit including four sets of process cartridges 18Y, 18M, 18C, and 18K for forming images of each color of yellow (Y), magenta (M), cyan (C), and black (K). 20 is provided. Y, M, C, and K attached to the numbers of the respective symbols indicate members for yellow, cyan, magenta, and black (the same applies hereinafter). In addition to the process cartridges 18Y, 18M, 18C, and 18K, an optical writing unit 21, an intermediate transfer unit 17, a secondary transfer device 22, a resist roller pair 49, a belt fixing type fixing device 25, and the like are disposed. .

  The optical writing unit 21 includes a light source (not shown), a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates a laser beam onto the surface of the photoreceptor 1 described later based on image data.

  The process cartridges 18Y, 18M, 18C, and 18K include a drum-shaped photoconductor 1, a charging device, a developing device 4, a drum cleaning device, a static eliminator, and the like.

The yellow process cartridge 18Y will be described below.
The surface of the photoreceptor 1Y is uniformly charged by a charging device as charging means. The surface of the photoreceptor 1 </ b> Y that has been subjected to charging processing is irradiated with laser light that has been modulated and deflected by the optical writing unit 21. Then, the potential of the irradiation part (exposure part) is attenuated. By this attenuation, an electrostatic latent image for Y is formed on the surface of the photoreceptor 1Y. The formed electrostatic latent image for Y is developed by the developing device 4Y as developing means to become a Y toner image.
The Y toner image formed on the Y photoconductor 1Y is primarily transferred to an intermediate transfer belt 110 described later. The surface of the photoreceptor 1Y after the primary transfer is cleaned of the transfer residual toner by a drum cleaning device.
In the Y process cartridge 18Y, the photoconductor 1Y cleaned by the drum cleaning device is discharged by the charge eliminator. Then, it is uniformly charged by the charging device and returns to the initial state. The series of processes as described above is the same for the other process cartridges 18M, 18C, and 18K.

Next, the intermediate transfer unit will be described.
The intermediate transfer unit 17 includes an intermediate transfer belt 110, a belt cleaning device 90, and the like. Further, it also includes a tension roller 14, a driving roller 15, a secondary transfer backup roller 16, four primary transfer bias rollers 62Y, M, C, and K.
The intermediate transfer belt 110 is tensioned by a plurality of rollers including the tension roller 14. Then, it is endlessly moved clockwise in the drawing by the rotation of the driving roller 15 driven by a belt driving motor (not shown).
The four primary transfer bias rollers 62Y, 62M, 62C, and 62K are disposed so as to be in contact with the inner peripheral surface side of the intermediate transfer belt 110, respectively, and receive primary transfer bias from a power source (not shown). Further, the intermediate transfer belt 110 is pressed toward the photoreceptors 1Y, 1M, 1C, and 1K from the inner peripheral surface side to form primary transfer nips. In each primary transfer nip, a primary transfer electric field is formed between the photoreceptor 1 and the primary transfer bias roller 62 due to the influence of the primary transfer bias.
The above-described Y toner image formed on the Y photoconductor 1Y is primarily transferred onto the intermediate transfer belt 110 due to the influence of the primary transfer electric field and nip pressure. On the Y toner image, the M, C, K toner images formed on the M, C, K photoconductors 1M, C, K are sequentially superposed and primarily transferred. By this primary transfer of superposition, a four-color superposed toner image (hereinafter referred to as a four-color toner image) that is a multiple toner image is formed on the intermediate transfer belt 110.
The four-color toner image superimposed and transferred onto the intermediate transfer belt 110 is secondarily transferred onto a transfer sheet (not shown) as a recording medium at a secondary transfer nip described later. Transfer residual toner remaining on the surface of the intermediate transfer belt 110 after passing through the secondary transfer nip is cleaned by a belt cleaning device 90 that sandwiches the belt with the driving roller 15 on the left side in the drawing.

Next, the secondary transfer device 22 will be described.
Below the intermediate transfer unit 17 in the figure, a secondary transfer device 22 is disposed in which a paper conveying belt 24 is stretched by two stretching rollers 23. The paper transport belt 24 is moved endlessly in the counterclockwise direction in the drawing in accordance with the rotational drive of at least one of the stretching rollers 23. One of the two stretching rollers 23 arranged on the right side in the drawing sandwiches the intermediate transfer belt 110 and the paper transport belt 24 between the secondary transfer backup roller 16 of the intermediate transfer unit 17. It is out. By this sandwiching, a secondary transfer nip is formed in which the intermediate transfer belt 110 of the intermediate transfer unit 17 and the paper transport belt 24 of the secondary transfer device 22 are in contact with each other. A secondary transfer bias having a polarity opposite to that of the toner is applied to the one stretching roller 23 by a power source (not shown). By applying this secondary transfer bias, the four-color toner image on the intermediate transfer belt 110 of the intermediate transfer unit 17 is electrostatically moved from the belt side toward the one stretching roller 23 side in the secondary transfer nip. A next transfer electric field is formed. The transfer paper fed into the secondary transfer nip so as to synchronize with the four-color toner image on the intermediate transfer belt 110 by a registration roller pair 49 to be described later has four colors affected by the secondary transfer electric field and nip pressure. The toner image is secondarily transferred. Instead of the secondary transfer method in which the secondary transfer bias is applied to one of the stretching rollers 23 as described above, a charger for charging the transfer paper in a non-contact manner may be provided.

  In the paper feeding device 200 provided at the lower part of the copying machine 500 main body, a plurality of paper feeding cassettes 44 in which a plurality of transfer sheets can be stacked and stored in a bundle of sheets are arranged so as to overlap each other in the vertical direction. It is installed. Each paper feed cassette 44 presses the paper feed roller 42 against the uppermost transfer paper in the paper bundle. Then, by rotating the paper feed roller 42, the uppermost transfer paper is sent out toward the paper feed path 46.

  The paper feed path 46 that receives the transfer paper fed from the paper feed cassette 44 has a plurality of conveying roller pairs 47 and a registration roller pair 49 provided near the end in the path. Then, the transfer paper is conveyed toward the registration roller pair 49. The transfer sheet conveyed toward the registration roller pair 49 is sandwiched between the rollers of the registration roller pair 49. On the other hand, in the intermediate transfer unit 17, the four-color toner image formed on the intermediate transfer belt 110 enters the above-described secondary transfer nip as the belt moves endlessly. The registration roller pair 49 sends out the transfer paper sandwiched between the rollers at a timing at which the transfer paper can be brought into close contact with the four-color toner image at the secondary transfer nip. Thereby, in the secondary transfer nip, the four-color toner image on the intermediate transfer belt 110 is in close contact with the transfer paper. Then, it is secondarily transferred onto the transfer paper and becomes a full color image on the white transfer paper. The transfer paper on which the full-color image is formed in this manner exits the secondary transfer nip as the paper transport belt 24 moves endlessly, and then is sent from the paper transport belt 24 to the fixing device 25.

  The fixing device 25 includes a belt unit that moves the fixing belt 26 endlessly while being stretched by two rollers, and a pressure roller 27 that is pressed toward one roller of the belt unit. The fixing belt 26 and the pressure roller 27 are in contact with each other to form a fixing nip, and the transfer paper received from the paper transport belt 24 is sandwiched therebetween. Of the two rollers in the belt unit, the roller that is pressed from the pressure roller 27 has a heat source (not shown) inside, and pressurizes the fixing belt 26 by the heat generated therefrom. The pressed fixing belt 26 heats the transfer paper sandwiched in the fixing nip. The full color image is fixed on the transfer paper by the influence of the heating and the nip pressure.

  The transfer paper subjected to the fixing process in the fixing device 25 is stacked on the stack portion 57 provided outside the left side plate in the drawing of the printer housing, or forms a toner image on the other surface. To the secondary transfer nip described above.

  When a document (not shown) is copied, for example, a bundle of sheet documents is set on the document table 30 of the automatic document feeder 400. However, when the original is a single-sided original that is closed in a main form, it is set on the contact glass 32. Prior to this setting, the automatic document feeder 400 is opened with respect to the copying machine 500, and the contact glass 32 of the scanner 300 is exposed. Thereafter, the single-bound original is pressed by the closed automatic document feeder 400.

  When a copy start switch (not shown) is pressed after the document is set in this way, the document reading operation by the scanner 300 starts. However, when a sheet document is set on the automatic document feeder 400, the automatic document feeder 400 automatically moves the sheet document to the contact glass 32 prior to the document reading operation. In the document reading operation, first, the first traveling body 33 and the second traveling body 34 start traveling together, and light is emitted from a light source provided in the first traveling body 33. Then, the reflected light from the document surface is reflected by a mirror provided in the second traveling body 34, passes through the imaging lens 35, and then enters the reading sensor 36. The reading sensor 36 constructs image information based on the incident light.

  In parallel with such a document reading operation, each device in each of the process cartridges 18Y, 18M, 18C, 18K, the intermediate transfer unit 17, the secondary transfer device 22, and the fixing device 25 starts driving. Based on the image information constructed by the reading sensor 36, the optical writing unit 21 is driven and controlled, and Y, M, C, and K toner images are formed on the respective photoreceptors 1Y, 1M, 1C, and 1K. Is done. These toner images become four-color toner images superimposed and transferred on the intermediate transfer belt 110.

  Further, almost simultaneously with the start of the document reading operation, the paper feeding operation is started in the paper feeding device 200. In this paper feeding operation, one of the paper feeding rollers 42 is selectively rotated, and the transfer paper is sent out from one of the paper feeding cassettes 44 accommodated in the paper bank 43 in multiple stages. The fed transfer sheets are separated one by one by the separation roller 45 and enter the reverse feeding path 46, and then conveyed toward the secondary transfer nip by the conveyance roller pair 47. In some cases, paper feeding from the manual feed tray 51 is performed instead of such paper feeding from the paper feeding cassette 44. In this case, after the manual feed roller 50 is selectively rotated to feed the transfer paper on the manual feed tray 51, the separation roller 52 separates the transfer paper one by one and feeds it to the manual feed path 53 of the printer unit 100. Make paper.

  When the copier 500 forms an image of another color composed of toner of two or more colors, the intermediate transfer belt 110 is stretched so that the upper stretched surface thereof is substantially horizontal, and all the upper stretched surface is placed on the upper stretched surface. Photoconductors 1Y, 1M, 1C, and 1K are brought into contact with each other. On the other hand, when forming a monochrome image consisting of only K toner, the intermediate transfer belt 110 is tilted to the lower left in the drawing by a mechanism (not shown) and the upper stretched surface is set to Y, M, C. The photoconductors 1Y, 1M, and 1C are separated. Of the four photoconductors 1Y, 1M, 1C, and 1K, only the K photoconductor 1K is rotated counterclockwise in the drawing to form only the K toner image. At this time, for Y, M, and C, not only the photoreceptor 1 but also the developing device is stopped to prevent unnecessary consumption of the photoreceptor 1 and the developer.

  The copying machine 500 includes a control board that is a control unit (not shown) that includes a CPU that controls each device in the copying machine 500. Furthermore, an operation panel (hereinafter referred to as “operating panel”), which is an operation display unit (not shown) constituted by a liquid crystal display, various key buttons, and the like, is provided. The operator sends a command to the control board by a key input operation on the operation panel, and selects one of the three modes for the single-sided printing mode, which is a mode for forming an image only on one side of the transfer paper. You can choose. The three single-sided printing modes include a direct discharge mode, a reverse discharge mode, and a reverse decal discharge mode.

FIG. 1 is an enlarged schematic configuration diagram showing the developing device 4 and the photosensitive member 1 included in one of the four process cartridges 18Y, 18M, 18C, and 18K in FIG. Since the four process cartridges 18Y, 18M, 18C, and 18K have substantially the same configuration except that the colors of the toners to be handled are different, they are referred to as “Y”, “M”, “C”, and “K” in FIG. Subscripts are omitted.
As shown in FIG. 1, the surface of the photosensitive member 1 is charged by a charging device (not shown) while rotating in the direction of arrow G in the drawing. An electrostatic latent image is formed on the surface of the charged photoreceptor 1 by the laser light emitted from the optical writing unit 21 which is an exposure device. Toner is supplied from the developing device 4 to the electrostatic latent image on the surface of the photoreceptor 1 on which the electrostatic latent image is formed, and a toner image is formed.

The developing device 4 has a developing roller 5 as a developer carrying member for supplying toner to the latent image on the surface of the photoreceptor 1 while moving the surface in the direction of arrow I in the drawing. Further, a supply screw 8 is provided as a supply / conveying member that conveys the developer toward the front of FIG. 1 while supplying the developer to the developing roller 5. The supply screw 8 is a developer conveying screw that includes a rotating shaft and a blade portion provided on the rotating shaft and conveys the developer in the axial direction by rotating.
A developer regulation that regulates the developer supplied to the developing roller 5 to a thickness suitable for development at a position facing the developing roller 5 on the downstream side in the surface movement direction from a portion facing the supply screw 8 of the developing roller 5. A developing doctor 12 is provided as a member.
The developed developer that has passed through the developing section is collected downstream from the developing section, which is the facing portion of the developing roller 5 with respect to the photoconductor 1, and the collected developer is collected in the same direction as the supply screw 8. A recovery screw 6 is provided as a recovery transport member for transporting to the front. A supply conveyance path 9 provided with the supply screw 8 is arranged in the lateral direction of the developing roller 5, and a collection conveyance path 7 as a developer collection conveyance path provided with the collection screw 6 is arranged in parallel below the development roller 5.

The developing device 4 is provided with a stirring conveyance path 10 in parallel with the collection conveyance path 7 below the supply conveyance path 9. The agitating and conveying path 10 includes an agitating screw 11 as an agitating and conveying member that conveys the developer in the back direction in the figure, which is the opposite direction to the supply screw 8 while agitating the developer.
The supply conveyance path 9 and the stirring conveyance path 10 are partitioned by a first partition wall 133 as a partition member. In the first partition wall 133, the supply conveyance path 9 and the agitation conveyance path 10 are partitioned at both ends on the front side and the back side in the drawing, and the supply conveyance path 9 and the agitation conveyance path 10 communicate with each other. is doing.
The supply conveyance path 9 and the recovery conveyance path 7 are both partitioned by the first partition wall 133, but an opening is provided at a location where the supply conveyance path 9 and the recovery conveyance path 7 of the first partition wall 133 are partitioned. Absent.
Further, the two conveyance paths of the stirring conveyance path 10 and the collection conveyance path 7 are partitioned by a second partition wall 134 as a partition member. The second partition wall 134 has an opening on the front side in the figure, and the agitation transport path 10 and the collection transport path 7 communicate with each other.
The supply screw 8, the recovery screw 6, and the stirring screw 11 that are developer conveying members are made of resin or metal screws. The screw diameter, screw pitch width, number of wings, etc. of each screw may be the same for all screws, or may be different for each screw.

The developer thinned by the developing doctor 12 made of stainless steel on the developing roller 5 is transported to a developing area which is a portion facing the photosensitive member 1 for development. The surface of the developing roller 5 is V-groove or sandblasted and is made of an Al or SUS base tube of φ25 [mm], and the gap between the developing doctor 12 and the photoreceptor 1 is about 0.3 [mm].
The developer after development is collected in the collection conveyance path 7, conveyed to the front side of the cross section in FIG. 1, and to the stirring conveyance path 10 through the opening of the second partition wall 134 provided in the non-image area. Developer is transferred. The toner is supplied to the stirring and conveying path 10 from the toner supply port 95 provided on the upper side of the stirring and conveying path 10 near the opening of the second partition wall 134 on the upstream side in the developer conveying direction in the stirring and conveying path 10. .

Next, the circulation of the developer in the three developer conveyance paths will be described.
FIG. 3 is a perspective sectional view of the developing device 4 for explaining the flow of the developer in the developer transport path. Each arrow in the figure indicates the moving direction of the developer.
4 is a schematic diagram of the flow of the developer in the developing device 4. Like FIG. 3, each arrow in the drawing indicates the moving direction of the developer.

In the supply conveyance path 9 that has been supplied with the developer from the agitation conveyance path 10, the developer is conveyed downstream in the conveyance direction of the supply screw 8 while supplying the developer to the developing roller 5. Then, the excess developer that is supplied to the developing roller 5 and is not used for development and is transported to the downstream end in the transport direction of the supply transport path 9 is supplied to the stirring transport path 10 from the surplus opening 92 of the first partition wall 133 ( Arrow E) in FIG.
The collected developer that is sent from the developing roller 5 to the collection conveyance path 7 and conveyed to the downstream end in the conveyance direction of the collection conveyance path 7 by the collection screw 6 is supplied to the stirring conveyance path 10 from the collection opening 93 of the second partition wall 134. (Arrow F in FIG. 4).
The agitating and conveying path 10 agitates the supplied surplus developer and the recovered developer, conveys the agitating screw 11 to the downstream side in the conveying direction, and conveys it to the upstream side in the conveying direction of the supplying screw 8. It is supplied to the supply conveyance path 9 from the supply opening 91 of 133 (arrow D in FIG. 4).
In the agitating and conveying path 10, the agitating screw 11 agitates and conveys the collected developer, the surplus developer, and the toner replenished as necessary in the transfer unit in the direction opposite to the developer in the collecting and conveying path 7 and the supply conveying path 9. . Then, the agitated developer is transferred to the upstream side in the conveyance direction of the supply conveyance path 9 communicating with the downstream side in the conveyance direction. A toner concentration sensor (not shown) is provided below the agitation transport path 10, and a toner supply control device (not shown) is operated by the sensor output to supply toner from a toner storage portion (not shown).

  In the developing device 4 shown in FIG. 4, a supply conveyance path 9 and a collection conveyance path 7 are provided, and developer supply and collection are performed in different developer conveyance paths, so that the developed developer is supplied to the supply conveyance path 9. There is no contamination. Accordingly, it is possible to prevent the toner density of the developer supplied to the developing roller 5 from decreasing toward the downstream side of the supply conveyance path 9 in the conveyance direction. Further, since the recovery conveyance path 7 and the agitation conveyance path 10 are provided and the developer recovery and agitation are performed in different developer conveyance paths, the developed developer does not fall during the agitation. Therefore, since the sufficiently agitated developer is supplied to the supply conveyance path 9, it is possible to prevent the developer supplied to the supply conveyance path 9 from being insufficiently agitated. In this way, the toner density of the developer in the supply conveyance path 9 can be prevented from decreasing, and the developer in the supply conveyance path 9 can be prevented from being insufficiently stirred. Can be constant.

As shown in FIG. 4, the developer moves from the lower part to the upper part of the developing device 4 only by the arrow D. The movement of the developer indicated by an arrow D is to push the developer by rotating the stirring screw 11 so that the developer is raised and supplied to the supply conveyance path 9.
Such movement of the developer gives stress to the developer and contributes to a decrease in the life of the developer.
When the developer is lifted from the bottom to the top, stress is applied to the developer, and the carrier film in the developer is scraped off and the toner is spent on the spot. Accordingly, the stability of the image quality is maintained. It will disappear.
Therefore, the life of the developer can be extended by reducing the stress of the developer in the movement of the developer indicated by the arrow D. By prolonging the life of the developer, it is possible to provide a developing device that prevents deterioration of the developer and is always stable in image quality without image density unevenness.

Next, the position at which toner is supplied to the developer conveyance path including the supply conveyance path 9, the agitation conveyance path 10 and the collection conveyance path 7 of the developing device 4 will be described. FIG. 5 is an external perspective view of the developing device 4.
As shown in FIG. 5, a toner replenishing port 95 for replenishing toner is provided above the upstream end of the agitating and conveying path 10 in which the agitating screw 11 is arranged in the conveying direction.
Further, the toner replenishing port 95 is not limited to the position above the upstream end portion in the transport direction of the stirring transport path 10 and may be provided above the downstream end portion of the collection transport path 7.
Further, a toner replenishing port 95 may be provided directly above the collection opening 93 where the developer is transferred from the collection conveyance path 7 to the stirring conveyance path 10. Furthermore, since the developer is likely to be mixed in the collection opening 93 serving as a delivery unit, the developer can be more efficiently stirred by replenishing at this position.

Next, replacement of the developer in the developing device 4 will be described.
A toner replenishment control device (not shown) that is a developer replenishing unit replenishes toner in a toner storage unit (not shown) to the developing device 4 from the toner replenishing port 95. In the developing device 4 of this embodiment, a developer including toner and a carrier is supplied from a toner supply port 95 of the developing device 4. Hereinafter, the developer in which the toner supplied to the developing device 4 and the carrier are mixed is referred to as premix toner. Note that the present invention is not limited to replenishing premixed toner, and a carrier and toner may be replenished separately to the developing device 4.
In addition, when the amount of developer in the developing device 4 becomes larger than necessary due to replenishment of premixed toner or the like, the supply conveyance path 9 has a part of the developer in the supply conveyance path 9 to the outside of the development device 4. And a discharge conveyance path 2 including a discharge conveyance screw 2 a for conveying the developer discharged from the developer discharge port 94 to the outside of the developing device 4. The discharge conveyance path 2 is arranged on the downstream side in the conveyance direction of the supply conveyance path 9 so as to be adjacent to the supply conveyance path 9 with a discharge opening member 135 described later in detail, and the developer discharge port 94 is connected to the supply conveyance path 9. It is an opening provided in the discharge opening member 135 so as to communicate with the discharge conveyance path 2.
In the present embodiment, the developer discharge port 94 is opened with a width of 39 [mm] from the rear end in the developer transport direction, but the present invention is not limited to this, and the developer that is flipped up as described later is used. What is necessary is just to open so that a chemical | medical agent can be discharged | emitted to the discharge conveyance path 2. FIG.
As described above, in the developing device 4, when the amount of the developer in the developing device 4 becomes larger than necessary due to the replenishment of the premix toner, a part of the developer in the supply conveyance path 9 to the outside of the developing device 4. Is discharged. Accordingly, since the developer in the developing device 4 can be gradually replaced without performing the carrier replacement operation, the maintenance can be simplified.

Next, the developing device 4 provided with the developer discharge port 94 will be described.
In the developing device 4 of this embodiment, the developer discharge port 94 is provided in the vicinity of the downstream end in the transport direction of the supply transport path 9.
The vicinity of the downstream end of the supply conveyance path 9 in the conveyance direction is, for example, the same position in the conveyance direction of the developer conveyance section 9 and the supply conveyance path 9 where the developer is transferred from the supply conveyance path 9 to the stirring conveyance path 10. It is a place.

The rotation direction of the supply screw 8 in the supply conveyance path 9 is clockwise (in the direction of arrow M) with respect to the conveyance direction of the supply screw 8 in FIG. It is rotating in the direction of lifting and feeding. Here, when the developer is supplied to the developing roller 5 so that the rotation direction of the supply screw 8 is counterclockwise with respect to the conveying direction and the developer is sprinkled from above, the developer is supplied to the developing roller 5 while being scattered. The On the other hand, when the rotation direction of the supply screw 8 is clockwise with respect to the conveyance direction as shown in FIG. 1, the developing roller 5 is developed to lift the developer from below the supply conveyance path 9 where the developer is accumulated. The agent comes to be supplied. The developer supply performance is more stable when the developer is supplied from the lower side than when the developer is supplied while being scattered. Therefore, in the developing device 4, the rotation direction of the supply screw 8 is counterclockwise in FIG. 1 (in FIG. 1). In the direction of arrow M).
In particular, in the case where the developer supplied to the developing roller 5 is not returned to the supply conveyance path 9 but is collected to the collection conveyance path 7 as in the developing device 4 of this embodiment, the amount of developer goes downstream of the supply conveyance path 9. It decreases according to. For this reason, it is more excellent in terms of developer supply that the developer is drawn up from below and supplied to the developing roller 5.

  Here, by being conveyed, the developer in the supply conveyance path 9 jumps by the rotating force of the supply screw 8 which is a developer conveyance screw. As shown in FIG. 1, the developer discharge port 94 is provided at a predetermined height above the upper end of the wing portion of the supply screw 8 in the supply conveyance path 9 which is a developer conveyance path. The developer that has jumped along the path indicated by arrow P in FIG. 1 flies and passes through the developer discharge port 94 (arrow K in FIG. 4) and is discharged.

In FIG. 1, the path of the jumped developer toward the developer discharge port 94 is indicated by an arrow P. The arrow P schematically shows the path of the jumped developer toward the developer discharge port 94, and the path of the jumped developer toward the developer discharge port 94 is limited to that indicated by the arrow P. is not.
A toner replenishment control device (not shown) that is a developer replenishing unit replenishes the developing device 4 with premixed toner in a toner storage unit (not shown) from the toner replenishment port 95.
In the developing device 4 of the present embodiment, the circulation conveyance path that conveys the excess developer that has reached the downstream end in the conveyance direction of the supply conveyance path 9 to the upstream end in the conveyance direction of the supply conveyance path 9 is the agitation conveyance path 10. In addition, the circulating and conveying member that applies a conveying force to the developer in the agitating and conveying path 10 that is a circulating and conveying path is the agitating screw 11. Further, the circulation opening provided near the downstream end in the conveyance direction of the supply conveyance path 9 and through which the passed developer is transferred to the agitation conveyance path 10 which is a circulation conveyance path is a surplus opening 92. Further, the developing device 4 includes a developer discharge port 94 as a discharge opening through which the developer that has passed is discharged to the outside of the developing device 4. The developer that has passed through the developer discharge port 94 is transferred to the discharge conveyance path 2, and is conveyed to the outside of the developing device 4 by rotating the discharge conveyance screw 2 a that is a discharge conveyance member, and is discharged from the development device 4. Is made.

FIG. 6 is a block diagram schematically showing a control system of the copying machine 500. As shown in FIG. 6, the control board 88 as a control unit controls the drive of each member by controlling the motor of each member. The three developer conveying screws in the developing device 4 and the drive source of the photosensitive member 1 are a main motor 89 in FIG. The main motor 89 can change its driving speed to a plurality of types of settings. When an image is formed on a thick paper, the control board 88 is set so as to have a slower driving speed than when an image is formed on a normal transfer paper. Is controlled by By controlling the drive speed of the main motor 89, the rotation speed of the supply screw 8 using the main motor 89 as a drive source can be controlled.
The replenishment of premixed toner by a toner replenishing device (not shown) is controlled by the control board 88 controlling the toner clutch of the toner replenishing device based on the detection results of the P sensor and the density sensor. .

Next, the characteristic part of the developing device 4 of the present embodiment will be described.
The developing device 4 includes a control board 88 as screw rotation speed control means for controlling the rotation speed of the supply screw 8 to a plurality of settings outside the casing forming the three developer conveyance paths. By controlling the driving speed of the main motor 89 by the control board 88, the rotational speeds of the photoconductor 1, the developing roller 5, each developer conveying screw, and the like during image formation are determined. Further, as described with reference to FIG. 14, the height at which the supply screw 8 jumps up the developer increases as the rotation speed of the supply screw 8 increases, and decreases as the rotation speed decreases.

  Information on the driving speed of the main motor 89 output from the control board 88 to the main motor 89 is information on the rotational speed of the supply screw 8. Based on this information, the developing device 4 adjusts the height of the lower end portion for discharging the developer at the developer discharge port 94 which is a discharge opening.

Specifically, based on the information on the rotational speed of the supply screw 8, when the rotational speed of the supply screw 8 is high, the height of the lower end portion of the developer discharge port 94 is adjusted to be high. On the other hand, when the rotation speed of the supply screw 8 is slow, the height of the lower end portion of the developer discharge port 94 is adjusted to be low.
As described above, the amount of developer discharged by adjusting the supply screw 8 by adjustment can be made substantially constant if the amount of increase in the developer amount in the developing device 4 is the same. That is, even if the image forming speed is different, if the image area ratio of the images to be formed is the same, the developer discharge amount per number of sheets can be made substantially the same. Thereby, it is possible to prevent the developer in the developing device 4 from being less than the required amount and the image from being lost. In contrast, the developer amount does not increase too much, causing the developer to move around on the developing roller 5 to cause density unevenness, and the developer does not overflow from the developing device 4 and scatter into the copying machine 500. Stable image output can be maintained.

Next, the discharge lower end height adjusting means of the developing device 4 shown in FIG. 1 will be described.
The discharge lower end height adjusting means of the developing device 4 is an opening position height adjusting means for adjusting the height of the position of the developer discharge port 94 according to the rotational speed of the supply screw 8.
As shown in FIG. 1, the casing forming the supply conveyance path 9 of the developing device 4 is provided with a casing opening 97 which is an opening larger than the developer discharge port at a position where the developer discharge port 94 is provided. Further, a discharge opening member 135 having a shape in which the developer discharge port 94 is provided in the shielding member is disposed at a position facing the casing opening 97. The discharge opening member 135 shields the casing opening 97 other than the region facing the developer discharge port 94, and allows the developer to pass only in the region where the developer discharge port 94 and the casing opening 97 are opposed. . Further, the discharge opening member 135 is movable in the vertical direction as indicated by arrows A and B in FIG. Then, a solenoid 98 as a discharge opening member raising / lowering means for moving the discharge opening member 135 up and down and a spring 99 are provided, and a control board 88 as a discharge opening member raising / lowering control means controls the solenoid 98.

  In the developing device 4, the control board 88 serving as the discharge opening member lifting / lowering control means, the solenoid 98 serving as the discharge opening member lifting / lowering means, and the spring 99 constitute opening position height adjusting means, and the position of the developer discharge port 94. Adjust the height. The height of the lower end portion of the developer discharge port 94 can also be adjusted by adjusting the height of the position of the developer discharge port 94.

  In the developing device 4, when the solenoid 98 is controlled to move the discharge opening member 135 in the direction of arrow A in FIG. 1, the developer discharge port 94 is moved to a higher position, and conversely in the direction of arrow B in FIG. The developer discharge port 94 can be installed at a low position. The discharge opening member 135 includes a solenoid 98 that is slid in the A-B direction, and a spring 99 that returns the position of the discharge opening member 135 when the drive of the solenoid 98 is stopped. The discharge opening member raising / lowering means is not limited to the solenoid 98, and a raising / lowering means using a cam may be used.

As shown in FIG. 6, the developing device 4 is controlled by a control board 88. In the case of image formation using normal paper, the image forming speed is made relatively high (normal image forming speed). On the other hand, in the case of image formation using thick paper, the main motor 89 is controlled so that the image forming speed is slower than in the case of normal paper. The supply screw 8 to which the driving force is transmitted from the main motor 89 is driven at a high rotational speed when the image forming speed is high, and is driven at a low rotational speed when the image forming speed is low.
When the rotational speed of the supply screw 8 is increased based on the image forming speed of the main motor 89, the discharge opening member 135 is positioned at a high position in the direction of arrow A in FIG. 1 without driving the solenoid 98. Set. On the other hand, when the rotational speed of the supply screw 8 is slow, the solenoid 98 is driven and the discharge opening member 135 is pulled downward to set the discharge opening member 135 at a low position in the direction of arrow B in FIG. To do.
Thereby, when the rotational speed of the supply screw 8 is fast, the height of the developer discharge port 94 can be increased, and the lower end portion of the developer discharge port 94 for discharging the developer can be increased. Further, when the rotation speed of the supply screw 8 is slow, the height of the developer discharge port 94 can be lowered, and the lower end portion of the developer discharge port 94 for discharging the developer can be lowered.

Therefore, in the developing device 4, the required amount of developer in the developing device 4 can be maintained even when the rotation speed of the supply screw 8 is fast, and when the rotational speed is slow, the developer amount in the developing device 4 is excessive. Can be prevented. For this reason, the developer in the apparatus can be replaced while the developer amount in the developing apparatus 4 is kept within a certain range. By keeping the amount of the developer in the developing device 4 within a certain range, it is possible to prevent the developer in the developing device 4 from being reduced and the image from being lost. On the other hand, the amount of toner does not increase so much that it travels on the developing roller 5 to cause density unevenness, and the developer does not overflow from the developing device 4 and scatter in the device. For this reason, the copying machine 500 including the developing device 4 can maintain stable image output.
In addition, by setting the height of the lower end of the developer discharge port 94 to be always higher than the height of the upper end of the wing portion of the supply screw 8, a slight amount of the developer is always raised by the splashing of the developer by the blade of the supply screw 8. It can suppress that an agent is discharged | emitted continuously.

[Modification 1]
In the above-described embodiment, the height of the lower end portion for discharging the developer at the developer discharge port 94 is adjusted by adjusting the height of the position of the developer discharge port 94. Hereinafter, a configuration in which the lower end of the substantial opening width through which the developer can pass through the developer discharge port 94 is adjusted without changing the position of the developer discharge port 94 will be described as Modification 1.

  FIG. 7 is an explanatory diagram of the first modification. FIG. 7A is a cross-sectional explanatory view of a portion where the developer discharge port 94 is provided in the supply conveyance path 9 of the developing device 4 of Modification 1. FIG. 7B is a developing device of Modification 1. FIG. 8 is an explanatory view of the shutter member 70 and the shutter support member 72 included in FIG. 4 when viewed from the direction of arrow H in FIG. 8 is an explanatory perspective view of the shutter member 70 and the supply screw 8. FIG. 9 is an explanatory view of a connecting portion between the shutter support member 72 at the axial end of the supply screw 8 and the supply screw 8. FIG. is there.

The developing device 4 of Modification 1 includes a shutter member 70, a shutter urging spring 75 that is a shutter urging member, and a screw rotational force transmitting unit that will be described in detail later, as a substantial opening width lower end adjusting unit. The shutter member 70 includes a shutter portion 71, a shutter frame 79, and a flange portion 74.
As shown in FIGS. 7 and 8, the shutter member 70 is fixed to a shutter support member 72. As shown in FIG. 9, the shutter support member 72 is connected to the rotating shaft 8a of the supply screw 8 via a shutter bearing 81. It is connected. As a result, as shown in FIGS. 7 and 8, the shutter member 70 is located on the outer peripheral side of the blade 8 b of the supply screw 8 at the same position as the developer discharge port 94 in the developer conveyance direction in the supply conveyance path 9. The rotary shaft 8a is disposed so as to be rotatable about the axis 8r. Further, the shutter member 70 blocks the space between the supply screw 8 and the developer discharge port 94 by the shutter portion 71 by rotating.
The shutter bearing 81 is a bearing that is sealed so that toner or the like does not enter the rotating portion. Further, the rotation shaft 8 a of the supply screw 8 is positioned with respect to the side plate 4 c of the developing device 4 via the screw bearing 82 on the outer side in the axial direction from the position where the shutter bearing portion 81 is provided.

The screw rotational force transmitting means for transmitting the rotational force of the supply screw 8 to the shutter member 70 is the developer T and the flange 74 in the supply conveyance path 9 in the developing device 4 of the first modification. The flange portion 74 is disposed at a position that always contacts the developer T in the supply conveyance path 9 on the outer peripheral side of the blade portion 8 b of the supply screw 8. Then, the flange portion 74 is pressed in the rotation direction of the supply screw 8 from the developer T that rotates as the supply screw 8 rotates, thereby transmitting a force that rotates in the rotation direction of the supply screw 8 to the shutter member 70. In such a screw rotational force transmitting means, the force with which the developer T pushes the flange portion 74 increases as the rotational speed of the supply screw 8 increases, and the force for rotating the shutter member 70 in the rotational direction of the supply screw 8 increases. . On the other hand, the slower the rotation speed of the supply screw 8, the smaller the force with which the developer T pushes the flange portion 74 and the weaker the force that rotates the shutter member 70 in the rotation direction of the supply screw 8.
The shutter urging spring 75 urges the shutter member 70 to rotate in the direction opposite to the rotation direction of the supply screw 8.

In the developing device 4 of the first modification, when the force for rotating the shutter member 70 of the screw rotational force transmitting means becomes larger than the force for urging the shutter member 70 of the shutter urging spring 75, the shutter member 70 moves the supply screw 8. Rotate in the direction of rotation. When the shutter member 70 rotates in the rotation direction of the supply screw 8, the shutter member 70 moves to the position 70a indicated by the broken line in FIG. 7A, and the shutter portion 71 also becomes the position 71a indicated by the broken line. As a result, the shutter portion 71 blocks the space between the lower portion of the developer discharge port 94 and the supply screw 8, thereby narrowing the substantial opening width of the developer discharge port 94.
On the other hand, when the rotation speed of the supply screw 8 becomes slow, the force for rotating the shutter member 70 of the screw rotational force transmitting means becomes smaller than the force for biasing the shutter member 70 of the shutter biasing spring 75. In this case, the shutter member 70 rotated in the rotation direction of the supply screw 8 rotates in the direction opposite to the rotation direction of the supply screw 8 by the biasing of the shutter biasing spring 75. The substantial opening width is widened by opening a portion of the space between the lower portion of the developer discharge port 94 and the supply screw 8 that is blocked by the shutter portion 71.
Thus, in the developing device 4 of the first modification, the substantial opening width can be adjusted according to the rotational speed of the supply screw 8.

Next, the change in the substantial opening width due to the change in the rotation speed of the supply screw 8 in Modification 1 will be described.
FIG. 10 is a schematic diagram for explaining the change in the position of the shutter portion 71 due to the difference in the rotation speed of the supply screw 8. FIG. 10A is a schematic diagram when the rotation speed of the supply screw 8 is relatively high (rotation speed when an image is formed on a normal sheet), and FIG. 10B shows the rotation speed of the supply screw 8. It is a schematic diagram when it is relatively slow (rotational speed when forming an image on thick paper).

As shown in FIG. 10A, when the rotation speed of the supply screw 8 is relatively fast, the shutter member 70 rotates in the rotation direction of the supply screw 8 (counterclockwise direction in FIG. 10), and the shutter portion. 71 comes to the position of Q in FIG. The positioning of the shutter portion 71 may be provided with an abutting member that restricts the shutter member 70 from rotating counterclockwise, or the shutter portion 71 stops at the position Q in FIG. The strength of the shutter urging spring 75 may be set.
As shown in FIG. 10A, when the space between the lower portion of the developer discharge port 94 and the supply screw 8 is blocked by the shutter portion 71, the space between the developer discharge port 94 and the supply screw 8 is blocked. The developer can be discharged only from the substantial opening width W that is not provided. Therefore, since the substantial opening width W becomes narrow at the rotation speed of the supply screw 8 at the normal paper image forming speed, the developer discharge amount is large in spite of the large amount of developer jumped up by the rotation of the supply screw 8. Will be less.
10A, when the developer amount in the supply conveyance path 9 is large and the developer surface Tf of the developer T is high, the developer splashed up by the supply screw 8 is It is discharged from the substantial opening width W. On the other hand, when the developer amount in the supply conveyance path 9 is small and the developer surface Tf of the developer T is low, even if the developer is splashed up by the supply screw 8, it does not hit the shutter portion 71 and is discharged.

As shown in FIG. 10B, when the rotation speed of the supply screw 8 is relatively slow, the force for moving the shutter member 70 in the rotation direction of the supply screw 8 (counterclockwise direction in FIG. 10) becomes small. . Therefore, when the shutter urging spring 75 urges the shutter member 70, the shutter portion 71 moves from the Q position to the R position. The positioning of the shutter portion 71 to the R position may be stopped by abutting or balanced by the shutter urging spring 75 as in the Q position.
In the state of FIG. 10B, since the shutter portion 71 is retracted to the position R, the substantial discharge opening width W is the entire developer discharge port 94. Therefore, since the substantial opening width W is wide at the rotation speed of the supply screw 8 at the image forming speed of the thick paper, the developer discharge amount is large although the amount of developer jumping up by the rotation of the supply screw 8 is small. Become. Thereby, when the developer amount in the supply conveyance path 9 is large and the developer surface Tf of the developer T is high, the developer splashed up by the supply screw 8 is higher than when the rotation speed of the supply screw 8 is high. Even if the jump-up reaching height is low, it is discharged from the substantial opening width W. On the other hand, when the developer amount in the supply conveyance path 9 is small and the developer surface Tf of the developer T is low, the developer splashed up by the supply screw 8 cannot reach the lower end of the developer discharge port 94. , Not discharged.

As described above, in the developing device 4 of Modification 1, when the rotation speed of the supply screw 8 is high, the lower end of the substantial opening width W is increased and the lower end of the developer discharge port 94 discharges the developer. Can be high. When the rotation speed of the supply screw 8 is slow, the lower end height of the substantial opening width W can be lowered, and the lower end portion for discharging the developer at the developer discharge port 94 can be lowered.
Therefore, in the developing device 4 of Modification 1, the required amount of developer in the developing device 4 can be maintained even when the rotation speed of the supply screw 8 is fast, and the development in the developing device 4 is performed when the rotational speed is slow. An excessive amount of the agent can be prevented. For this reason, the developer in the apparatus can be replaced while the developer amount in the developing apparatus 4 is kept within a certain range.

[Modification 2]
Next, as a second modification, the lower end of the substantial opening width through which the developer can pass through the developer discharge port 94 is adjusted by a mechanism different from that in the first modification without changing the position of the developer discharge port 94. The configuration will be described.

  FIG. 11 is an explanatory diagram of the second modification. FIG. 11A is a cross-sectional explanatory view of a portion where the developer discharge port 94 is provided in the supply conveyance path 9 of the developing device 4 of the second modification, and FIG. 11B is a developing device of the second modification. It is explanatory drawing which looked at the shutter member 70 and the shutter support member 72 with which 4 is provided from the arrow H direction in Fig.11 (a). As illustrated in FIG. 11, the shutter member 70 according to the second modification includes a guide member 76 having a guide width 76 w in the direction of the axis 8 r instead of the shutter frame 79 according to the first modification. Furthermore, it is the shape provided with the frame 76a between guides extended in an axial direction instead of the collar part 74 extended in an axial direction.

The developing device 4 of Modification 2 includes a shutter member 70, a shutter urging spring 75 that is a shutter urging member, and a screw rotational force transmitting unit that will be described in detail later. The shutter member 70 includes a shutter portion 71 and cylindrical guide members 76 provided at both ends of the shutter member 70.
As shown in FIG. 11, the shutter member 70 is fixed to the shutter support member 72 as in the first modification. Further, the connection between the shutter support member 72 and the supply screw 8 is the same as in the first modification, and the shutter support member 72 is connected to the rotating shaft 8a of the supply screw 8 via the shutter bearing 81 as shown in FIG. Has been. As a result, the shutter member 70 rotates around the axis 8r of the rotary shaft 8a on the outer peripheral side of the blade 8b of the supply screw 8 at the same position as the developer discharge port 94 in the developer transport direction in the supply transport path 9. Arranged to be possible. Further, the shutter member 70 blocks the space between the supply screw 8 and the developer discharge port 94 by the shutter portion 71 by rotating.

  In the developing device 4 of Modification 2, the screw rotational force transmitting means for transmitting the rotational force of the supply screw 8 to the shutter member 70 is a guide member 76 and a rubbing member for rubbing the inner peripheral surface of the guide member 76. And a rubbing pin 78. The rubbing pin 78 is attached to the supply screw 8 via a rubbing spring 77 that is an urging member, and rotates together with the supply screw 8. The rubbing spring 77 urges the tip of the rubbing pin 78 in a direction toward the rotation shaft 8 a of the supply screw 8. The sliding pin 78 jumps out in the outer peripheral direction of the supply screw 8 due to the centrifugal force generated by the rotation of the supply screw 8, and its tip contacts the inner peripheral surface of the guide member 76 and rubs. Then, a force that rotates in the rotation direction of the supply screw 8 is transmitted to the shutter member 70 by a frictional force between the distal end portion of the rubbing pin 78 and the inner peripheral surface of the guide member 76.

In such a screw rotational force transmitting means, when the rotational speed of the supply screw 8 is high, the centrifugal force acting on the rubbing pin 78 increases, and the rubbing pin 78 contacts the guide member 76 with a strong pressing force. As a result, the frictional force between the tip end portion of the rubbing pin 78 and the inner peripheral surface of the guide member 76 is increased, and the force for rotating the shutter member 70 of the screw rotational force transmitting means is increased. Therefore, as the rotation speed of the supply screw 8 increases, the force for rotating the shutter member 70 in the rotation direction of the supply screw increases.
On the other hand, when the rotation speed of the supply screw 8 is slow, the centrifugal force acting on the rubbing pin 78 becomes small, and the rubbing pin 78 contacts the guide member 76 with a weak pressing force. As a result, the frictional force between the tip of the rubbing pin 78 and the inner peripheral surface of the guide member 76 is reduced, and the force for rotating the shutter member 70 of the screw rotational force transmitting means is reduced. Therefore, the slower the rotation speed of the supply screw 8, the weaker the force that rotates the shutter member 70 in the rotation direction of the supply screw.
Further, the shutter urging spring 75 urges the shutter member 70 to rotate in the direction opposite to the rotation direction of the supply screw 8 as in the first modification.

Also in the developing device 4 of Modification 2, when the force for rotating the shutter member 70 of the screw rotational force transmitting means becomes larger than the force of urging the shutter member 70 of the shutter urging spring 75 as in Modification 1, the shutter member 70 rotates in the direction of rotation of the supply screw 8. When the shutter member 70 rotates in the rotation direction of the supply screw 8, the shutter portion 71 moves to a position 71a indicated by a broken line in FIG. As a result, the shutter portion 71 blocks the space between the lower portion of the developer discharge port 94 and the supply screw 8, thereby narrowing the substantial opening width of the developer discharge port 94.
On the other hand, when the rotation speed of the supply screw 8 becomes slow, the force for rotating the shutter member 70 of the screw rotational force transmitting means becomes smaller than the force for biasing the shutter member 70 of the shutter biasing spring 75. In this case, the shutter member 70 rotated in the rotation direction of the supply screw 8 rotates in the direction opposite to the rotation direction of the supply screw 8 by the biasing of the shutter biasing spring 75. The substantial opening width is widened by opening a portion of the space between the lower portion of the developer discharge port 94 and the supply screw 8 that is blocked by the shutter portion 71.
As described above, also in the developing device 4 of Modification 2, the substantial opening width can be adjusted according to the rotational speed of the supply screw 8.

Further, the change in the position of the shutter portion 71 due to the difference in the rotation speed of the supply screw 8 is the same as that of the first modification described with reference to FIG.
Therefore, even in the developing device 4 of the modified example 2, the required amount of developer in the developing device 4 can be maintained even when the rotation speed of the supply screw 8 is fast, and the development in the developing device 4 is performed when the rotational speed is slow. An excessive amount of the agent can be prevented. For this reason, the developer in the apparatus can be replaced while the developer amount in the developing apparatus 4 is kept within a certain range.

As described above, according to the present embodiment, the developing device 4 carries the developer on the surface and rotates, and if it is a latent image carrier, the toner is applied to the latent image on the surface of the photoconductor 1 at a position facing the photoconductor 1. The developing roller 5 is a developer carrying member for developing the toner. Further, a supply conveyance path 9 that conveys the developer along the axial direction of the developing roller 5 while supplying the developer to the developing roller 5 is provided. Further, it has a supply screw 8 that is composed of a rotating shaft 8a and a spiral wing portion 8b, and applies a conveying force to the developer in the supply conveying path 9 by rotating around the rotating shaft 8a. In addition, a stirring conveyance path 10 that is a circulation conveyance path for conveying the developer that has reached the downstream end in the conveyance direction of the supply conveyance path 9 to the upstream end in the conveyance direction of the supply conveyance path 9 is provided. In addition, it has a stirring screw 11 that is a circulating transport member that applies transport force to the developer in the stirring transport path 10. Further, a developer discharge port 94 that is a discharge opening through which the developer that has passed is discharged out of the developing device 4 is provided in the supply conveyance path 9. The developing device 4 has a control board 88 as a screw rotation speed control means for controlling the rotation speed of the supply screw 8 to a plurality of settings in a copying machine 500 as an image forming apparatus. Further, the opening position height adjusting means is used as a discharge lower end height adjusting means for adjusting the height of the lower end portion for discharging the developer at the developer discharge port 94 which is a discharge opening according to the rotational speed of the supply screw 8. A control board 88, a solenoid 98 and a spring 99 are included. In the developing device 4, the control board 88 controls the solenoid 98 to adjust the height of the developer discharge port 94 according to the rotational speed of the supply screw 8. As a result, the height of the lower end portion where the developer is discharged from the developer discharge port 94 is adjusted. That is, when the rotation speed of the supply screw 8 is high, the lower end of the developer discharge port 94 for discharging the developer is adjusted to be high, and when the rotation speed is low, the lower end of the supply screw 8 is low. Adjust so that Accordingly, the required amount of developer in the developing device 4 can be maintained even when the rotation speed of the supply screw 8 is fast, and the amount of developer in the developing device 4 becomes excessive even when the rotational speed is slow. Can be prevented. Therefore, in the developing device 4, the developer in the apparatus can be exchanged in a state where the developer amount in the apparatus is kept within a certain range.
Further, in the developing device 4, the discharge lower end height adjusting means is an opening position height adjusting means for adjusting the height of the position of the developer discharge port 94 which is a discharge opening according to the rotation speed of the supply screw. Since the height of the lower end portion of the developer discharge port 94 can be adjusted by adjusting the height of the position of the developer discharge port 94, the lower end of the developer discharge port 94 that discharges the developer. The height of the part can be adjusted.
Further, the developing device 4 includes a casing opening 97 that is a larger opening than the developer discharge port 94 at a position where a developer discharge port 94 that is a discharge opening is provided in the casing that forms the supply conveyance path 9. Further, in the shape in which the developer discharge port 94 is provided in the shielding member, the casing opening other than the region facing the developer discharge port 94 is disposed so as to be movable in the vertical direction to a position facing the casing opening 97. A discharge opening member 135 that shields the portion 97 is provided. Further, as an opening position height adjusting means, a solenoid 98 and a spring 99 which are discharge opening member raising / lowering means for moving the discharge opening member 135 in the vertical direction are provided. Further, based on the setting of the rotation speed of the supply screw 8 by the control board 88 which is a screw rotation speed control means, the solenoid 98 of the discharge opening member lifting / lowering means is controlled by the control board 88 having a function as the discharge opening member lifting / lowering control means. . Accordingly, the height of the position of the developer discharge port 94 provided in the discharge opening member 135 can be adjusted by controlling the drive of the solenoid 98 to move the discharge opening member 135 in the vertical direction.
Further, in the developing devices 4 of the first and second modified examples, the discharge lower end height adjusting means can substantially pass the developer through the developer discharge port 94 that is the discharge opening according to the rotation speed of the supply screw 8. This is a substantial opening width lower end adjusting means for adjusting the lower end of the opening width W. Accordingly, the height of the lower end portion of the developer discharge port 94 for discharging the developer can be adjusted without moving the position of the developer discharge port 94 itself.
Further, the developing device 4 of Modification 1 and Modification 2 includes a shutter member 70, a screw rotational force transmission means, and a shutter urging spring 75 which is a shutter urging member, as the substantial opening width lower end adjusting means. . The shutter member 70 has an axis 8r of the rotation shaft 8a on the outer peripheral side of the blade 8b of the supply screw 8 at the same position as the developer discharge port 94 which is a discharge opening in the developer conveyance direction in the supply conveyance path 9. It is arranged to be rotatable around the center. Further, the shutter member 70 includes a shutter portion 71 that blocks a part of the space between the supply screw 8 and the developer discharge port 94 as the shutter member 70 rotates. Further, the screw rotational force transmitting means transmits the force in the rotational direction of the supply screw 8 to the shutter member 70, and the shutter urging spring 75 causes the shutter member 70 to rotate in the direction opposite to the rotational direction of the supply screw 8. Energize. Further, the screw rotational force transmitting means increases the force that rotates the shutter member 70 in the rotational direction of the supply screw 8 as the rotational speed of the supply screw 8 increases. When the force for rotating the shutter member 70 of the screw rotational force transmitting means becomes larger than the force for urging the shutter member 70 of the shutter urging spring 75, the shutter member 70 rotates in the rotation direction of the supply screw 8. Accordingly, the shutter portion 71 of the shutter member 70 blocks the space between the lower portion of the developer discharge port 94 and the supply screw 8, thereby reducing the substantial opening width W. On the other hand, when the force for rotating the shutter member 70 of the screw rotational force transmitting means becomes smaller than the force for biasing the shutter member 70 of the shutter biasing spring 75, the shutter member 70 rotated in the rotation direction of the supply screw 8 returns. That is, the shutter member 70 rotates in the direction opposite to the rotation direction of the supply screw 8 by the biasing of the shutter biasing spring 75. Thus, the substantial opening width W is widened by opening a portion of the space between the lower portion of the developer discharge port 94 and the supply screw 8 that is blocked by the shutter portion 71. With such a configuration, the lower end of the substantial opening width W through which the developer at the developer discharge port 94 can pass can be adjusted according to the rotation speed of the supply screw 8.
Further, in the developing device 4 of the first modification, the screw rotational force transmitting means is a developer provided on the shutter member 70 and a developer T that rotates by the rotation of the supply screw 8 and presses the flange 74. The brim portion 74 is disposed at a position always in contact with the developer T in the supply conveyance path 9 on the outer peripheral side of the blade portion 8 b of the supply screw 8, and is supplied from the developer T that rotates as the supply screw 8 rotates. It is pressed in the rotational direction of the screw 8. In this way, when the flange 74 is pressed by the developer T, a force in the rotation direction of the supply screw 8 is transmitted to the shutter member 70. With such a screw rotational force transmitting means, the force that rotates the shutter member 70 in the rotational direction of the supply screw 8 can be increased as the rotational speed of the supply screw 8 increases.
Further, in the developing device 4 of Modification 2, the screw torque transmission means includes cylindrical discharge guide members 76 provided at both ends of the shutter member 70 in the direction of the axis 8r of the rotation shaft 8a, It comprises a rubbing pin 78 which is a rubbing member for rubbing the peripheral surface. The rubbing pin 78 is attached to the supply screw 8 via a rubbing spring 77 which is an urging member, and jumps out in the outer peripheral direction of the supply screw 8 by centrifugal force due to the rotation of the supply screw 8. The tip of the rubbing pin 78 comes into contact with the inner peripheral surface of the guide member 76 and rubs to transmit the force in the rotation direction of the supply screw 8 to the shutter member 70. With such a screw rotational force transmitting means, the force that rotates the shutter member 70 in the rotational direction of the supply screw 8 can be increased as the rotational speed of the supply screw 8 increases.
Further, by providing the developer discharge port 94 so that the lower end of the developer discharge port 94 which is a discharge opening is higher than the upper end of the supply screw 8, the developer jumps up by the blades of the supply screw 8. It can suppress that a trace amount agent is always discharged | emitted continuously.
The copying machine 500 as an image forming apparatus includes at least the photosensitive member 1 as a latent image carrier, a charging device as a charging unit, an optical writing unit 21 as a latent image forming unit, and a developing unit. . By using the developing device 4 as the developing means of the copying machine 500, it is possible to prevent chipping of images, density unevenness, and scattering of the developer, so that stable image output can be maintained.

1 is a schematic configuration diagram of a developing device and a photoreceptor according to the present embodiment. 1 is a schematic configuration diagram of a copier according to an embodiment. FIG. 3 is a perspective cross-sectional view of the developing device for explaining the flow of the developer. FIG. 3 is a schematic diagram of a developer flow in a developing device. FIG. 1 is a block diagram schematically showing a control system of a copying machine. Explanatory drawing of the modification 1, (a) is sectional explanatory drawing of a developing device, FIG.5 (b) is explanatory drawing of a shutter member and a shutter support member. The perspective explanatory drawing of a shutter member and a supply screw. Explanatory drawing of the connection part of a shutter support member and a supply screw. Schematic diagram for explaining the change in the position of the shutter unit due to the difference in the rotational speed of the supply screw, (a) is an explanatory diagram when the rotational speed of the supply screw is relatively fast, and (b) is the rotational speed of the supply screw. Explanatory drawing when is relatively slow. Explanatory drawing of the modification 2, (a) is sectional explanatory drawing of a developing device, FIG.5 (b) is explanatory drawing of a shutter member and a shutter support member. The graph which shows the relationship between a developer surface height and the bounce-up arrival height. Explanatory view of the mechanism that causes a difference in the jumping height due to the difference in developer surface height, (a) is an explanatory diagram of a state where the developer surface height is low, and (b) is a diagram showing the developer surface height. Explanatory drawing of a high state. The graph which shows the relationship between the rotation speed of a supply screw, and a bounce-up arrival height.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Discharge conveyance path 2a Discharge conveyance screw 4 Developing apparatus 5 Developing roller 6 Collection screw 7 Collection conveyance path 8 Supply screw 8a Rotating shaft 8b Feather part 8r Axis 9 Supply conveyance path 10 Stirring conveyance path 11 Stirring screw 12 Developer doctor 14 Tension roller 15 Drive roller 16 Secondary transfer backup roller 17 Intermediate transfer unit 18 Process cartridge 20 Image forming unit 21 Optical writing unit 22 Secondary transfer device 23 Tension roller 24 Paper transport belt 25 Fixing device 26 Fixing belt 27 Pressure Roller 70 Shutter member 71 Shutter part 72 Shutter support member 74 Collar part 75 Shutter biasing spring 76 Guide member 76a Frame between guides 77 Sliding spring 78 Sliding pin 79 Shutter frame 90 Belt cleaning Position 91 Supply opening 92 Surplus opening 93 Recovery opening 94 Developer discharge port 95 Toner supply port 97 Casing opening 98 Solenoid 99 Spring 100 Printer unit 110 Intermediate transfer belt 133 First partition wall 134 Second partition wall 135 Discharge opening Element

Claims (9)

A developer carrying member that rotates by carrying a developer on the surface, and supplies toner to the latent image on the surface of the latent image carrying member at a position facing the latent image carrying member;
A supply conveyance path for conveying the developer along the axial direction of the developer carrier while supplying the developer to the developer carrier;
A supply screw that includes a rotation shaft and a spiral wing, and applies a conveyance force to the developer in the supply conveyance path by rotating about the rotation axis;
A circulation conveyance path for conveying the developer that has reached the downstream end in the conveyance direction of the supply conveyance path to the upstream end in the conveyance direction of the supply conveyance path;
A circulation conveyance member that applies a conveyance force to the developer in the circulation conveyance path;
In the developing device provided in the supply conveyance path with a discharge opening through which the developer that has passed is discharged out of the developing device,
Screw rotation speed control means for controlling the rotation speed of the supply screw to a plurality of settings;
A developing device comprising: a discharge lower end height adjusting means for adjusting a height of a lower end portion for discharging the developer in the discharge opening in accordance with a rotation speed of the supply screw. The developing device according to claim 1.
The developing apparatus according to claim 1, wherein the discharge lower end height adjusting means is an opening position height adjusting means for adjusting a height of a position of the discharge opening in accordance with a rotation speed of the supply screw. The developing device according to claim 2.
The casing that forms the supply conveyance path includes a casing opening that is a larger opening than the discharge opening at a position where the discharge opening is provided.
A shape in which the discharge opening is provided in the shielding member, is arranged so as to be movable in the vertical direction to a position facing the casing opening, and shields the casing opening other than the region facing the discharge opening. A discharge opening member
As the opening position height adjusting means, a discharge opening member lifting / lowering means for moving the discharge opening member in the vertical direction, and the discharge opening member lifting / lowering means based on the setting of the rotation speed of the supply screw by the screw rotation speed control means. A developing device comprising: a discharge opening member lifting control means for controlling. The developing device according to claim 1.
The discharge lower end height adjusting means is a substantial opening width lower end adjusting means for adjusting a lower end of a substantial opening width through which the developer of the discharge opening can pass according to a rotation speed of the supply screw. apparatus. The developing device according to claim 4.
As the substantial opening width lower end adjusting means, the developer can be rotated around the axis of the rotation shaft on the outer peripheral side from the blade portion of the supply screw at the same position as the discharge opening in the developer conveyance direction in the supply conveyance path. A shutter member that is disposed on and blocks a part of a space between the supply screw and the discharge opening by rotating,
Screw rotational force transmitting means for transmitting the force in the rotational direction of the supply screw to the shutter member;
A shutter urging member that urges the shutter member to rotate in a direction opposite to the rotation direction of the supply screw;
The screw rotational force transmitting means is such that the higher the rotational speed of the supply screw, the stronger the force that rotates the shutter member in the rotational direction of the supply screw.
When the force for rotating the shutter member of the screw rotational force transmitting means becomes larger than the force for urging the shutter member of the shutter urging member, the shutter member rotates in the rotation direction of the supply screw and the shutter The member narrows the substantial opening width by blocking the space between the lower part of the discharge opening and the supply screw,
When the force for rotating the shutter member of the screw rotational force transmitting means is smaller than the force for urging the shutter member of the shutter urging member, the shutter member rotated in the rotation direction of the supply screw is attached to the shutter. Rotating in the direction opposite to the rotation direction of the supply screw by the biasing of the biasing member,
A developing device that widens the substantial opening width by opening a portion of the space between the lower portion of the discharge opening and the supply screw that is blocked by the shutter member. The developing device according to claim 5.
The screw rotational force transmitting means includes a flange provided on the shutter member and a developer that rotates by the rotation of the supply screw and presses the flange.
The brim portion is disposed at a position always in contact with the developer in the supply conveyance path on the outer peripheral side of the wing portion of the supply screw, and the supply screw is rotated from the developer rotated by the rotation of the supply screw. And a force in the rotation direction of the supply screw is transmitted to the shutter member. The developing device according to claim 5.
The screw torque transmission means includes a cylindrical guide member provided at both ends of the shutter member in the axial direction of the rotation shaft, and a rubbing member that rubs the inner peripheral surface of the guide member.
The rubbing member is attached to the supply screw via a biasing member, and protrudes in the outer peripheral direction of the supply screw by a centrifugal force generated by the rotation of the supply screw, and its tip contacts the inner peripheral surface of the guide member. A developing device characterized by rubbing. The developing device according to claim 1, 2, 3, 4, 5, 6 or 7.
The developing device according to claim 1, wherein the discharge opening is provided so that a lower end of the discharge opening is higher than an upper end of the supply screw. At least a latent image carrier;
Charging means for charging the surface of the latent image carrier;
Latent image forming means for forming an electrostatic latent image on the latent image carrier;
In an image forming apparatus having developing means for developing the electrostatic latent image into a toner image,
An image forming apparatus using the developing device according to claim 1, 2, 3, 4, 5, 6, 7, or 8 as the developing means.

Images