JP4157907B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile machine, and a developing device used in the image forming apparatus, and more specifically, uses a two-component developer containing toner and a magnetic carrier and uses a complicated toner replenishing device. The present invention also relates to a developing device having a self-toner density control mechanism capable of controlling the toner density of the developer on the developer carrying member within a certain range, and an image forming apparatus including the device.

Conventionally, as a developing device of this type, the amount of developer carried and transported by a developer carrier having a magnetic field generating means disposed therein is regulated by the developer regulating member, and scraped off by the developer regulating member. The developer is stored in the developer storage section, and is stored in the toner storage section from the toner supply opening adjacent to the developer storage section from the upstream side in the developer transport direction and facing the surface of the developer carrier. A developing device for supplying toner to a developer on a developer carrying member is known (see, for example, JP-A-9-22178). In this developing device, the toner in contact with the transported developer carried on the developer carrying member at the toner replenishment opening is transferred between the transported developer and the contained developer contained in the developer containing portion. It is taken into the developer so as to be drawn from the interface. When the toner density of the developer on the developer carrying member increases, the volume of the developer increases, so that the accommodated developer accommodated in the developer accommodating portion extends to cover the toner supply opening. Thus, the toner uptake from the toner container in the toner supply opening to the developer on the developer carrying member is suppressed. Thereby, the toner concentration of the developer on the developer carrying member can be controlled within a certain range.
Further, a developing device is known in which a second developer regulating member having a predetermined gap with respect to the surface of the developer carrying member is provided between the developer containing portion and the toner supply opening of the toner containing portion. (See, for example, JP-A-9-197833). In this developing device, when the toner concentration of the developer on the developer carrying member increases, the layer thickness of the developer increases, and the passage of the increased developer is restricted by the second developer regulating member. The regulated developer covers the toner replenishment opening adjacent to the second developer regulating member from the upstream side in the developer conveyance direction, and is carried and conveyed from the toner storage portion onto the developer carrier. Suppresses toner incorporation into the developer. Thereby, the toner concentration of the developer on the developer carrying member can be controlled within a certain range.

  Thus, according to the developing device that controls the toner density of the developer on the developer carrying member within a certain range (hereinafter referred to as “self toner density control”), the toner density sensor is not necessary, and the paddle screw Therefore, the toner replenishing device can be simplified. Furthermore, compared with the conventional two-component development system, the number of magnetic carriers can be reduced, and the torque of the apparatus can be greatly reduced. From these things, there exists an advantage that size reduction and cost reduction of an apparatus can be achieved. Furthermore, since the toner in the toner container can be directly replenished to the developer on the developer carrying member that has passed through the development area, the toner on the developer carrying member on which the toner concentration has decreased is quickly increased. Can be replenished. Therefore, there is also an advantage that black solid followability is good.

  However, in the developing device that performs self-toner density control, background contamination and a decrease in development density occur over time, or the width direction perpendicular to the developer transport direction on the developer carrier (hereinafter referred to as “carrier width”). Development density unevenness may occur in the direction. As a result of intensive studies by the present inventors on the causes of these image quality degradations, it has been found that the following causes can be considered.

  As a cause of the above-mentioned background stain and a decrease in the development density, there is an early deterioration of the developer due to insufficient replacement of the developer on the developer carrying member and the developer staying in the developer container. Conceivable. Since the developer carried and transported on the developer carrier is carried away with almost no separation from the developer carrier, the developer staying in the developer container is hardly replaced. There is a case. If the developer is not replaced, the stress on the magnetic carrier in the developer carried on the developer carrying member becomes relatively high, and the magnetic carrier in the developer staying in the developer container is more May deteriorate early. If the magnetic carrier on the developer carrying member deteriorates early, the charging ability of the magnetic carrier on the developer carrying member that is actually engaged in image formation will be improved even if the entire developer in the developing device has not deteriorated so much. May decrease. This decrease in the charging ability of the magnetic carrier causes scumming or a decrease in the developing density, which unavoidably deteriorates the image quality and necessitates early replacement of the developer.

  In addition, when the developer on the developer carrying member and the developer staying in the developer container are not sufficiently replaced, there is a risk of causing toner charging failure. If the developer is not replaced, toner corresponding to the consumption amount is supplied and mixed almost only on the developer carrier, and a predetermined charge amount must be obtained. However, when the surface movement speed of the developer carrying member is fast (in the case of a developing roller, the rotation is several hundred rpm), the charging is not in time and there is a risk of causing a charging failure. In particular, if there is a portion where the toner consumption is high, the image quality will be deteriorated, such as a marked decrease in development density compared to other portions.

Further, the cause of uneven development density in the width direction of the carrier is considered to be uneven charging of toner in the width direction of the carrier.
When new toner is replenished to the toner consumption part of the developer, a delay in toner replenishment or a variation in the replenishment amount may occur. In a portion where the toner supply is insufficient due to such a delay in toner supply or variations in the supply amount, the toner density decreases and the toner charge amount increases. In particular, when an image with a large amount of toner consumption such as black solid is formed, toner replenishment to the developer that consumed a large amount of toner cannot catch up, and the next development may be performed with the toner density lowered. There is. In addition, since the toner is rapidly taken into the developer that has consumed a large amount of toner, the toner takes up momentum, and the excess toner is taken in, and the toner density in that portion is increased more than necessary. Development may be performed.
In addition, since toner is not consumed in the non-image portion, the toner should not be taken in originally, but there is a possibility that the toner is taken in slightly and the toner density increases and the toner charge amount decreases. .
As described above, when the developer on the developer carrying member in the width direction of the carrying member has a non-uniform state of toner concentration or toner charge amount, a portion having a low toner concentration and a high toner charge amount has a relatively white image ( A non-image portion having a high toner density and a low toner charge amount becomes a dark image, and uneven development density occurs in the width direction of the carrier.

  Further, the uneven development density in the width direction of the carrier may be caused by variations in the size or position of the toner replenishing opening in the toner accommodating portion in the width direction of the carrier, or a magnet roller as a magnetic field generating means built in the developer carrier. May also occur when the magnetic force varies in the width direction of the carrier.

  Furthermore, when the present inventors conducted further earnest studies, the cause of the development density unevenness in the width direction of the carrier is the surface roughness of the portion of the second developer regulating member facing the developer carrier, It has also been found that there is insufficient pressure to feed toner from the agitator provided in the toner containing portion. In the former, the surface roughness of the portion of the second developer regulating member facing the developer carrier affects the amount of toner taken into the developer, and the surface roughness is uneven in the width direction of the carrier. In this case, it is considered that the unevenness in the development density in the width direction of the carrier is caused because the toner intake amount is not uniform. The latter is a case where the toner delivery pressure of the agitator in the toner storage unit varies in the width direction of the carrier. If there is a part that does not reach the pressure necessary to send the toner to a part where the toner consumption is large, such as a black solid, the toner is insufficiently taken into the developer in that part, and thus in the width direction of the carrier. It is thought that uneven development density occurs.

  Note that the applicant of the present invention provides a developer for peeling off the developer on the developer carrying member in the developer accommodating portion, as the configuration including the second developer restricting member to prevent the uneven development density. A developing device provided with a peeling member and a developer stirring member for stirring the developer has been proposed (see Japanese Patent Application Laid-Open No. 10-232540). In this developing device, all the developer carried and conveyed on the developer carrying member in the developer accommodating portion is once peeled off by the developer peeling member (mylar), and the developer peeled off by the developer peeling member is stirred by the developer. The material is agitated. However, as a result of recent experimental studies conducted by the present inventors, in the configuration in which all of the developer on the developer carrying member is once peeled off in the developer container, the self toner density control tends to be unstable. In the worst case, it has been found that the toner density control may not function. The following can be considered as this cause. If all the developer on the developer carrying member is peeled off in the developer container, even if the toner concentration of the developer is increased, the developer peeled off from the developer peeling member is successively applied to the developer container. It will be accommodated until all the spaces are filled. For this reason, when the toner concentration increases, a force that suppresses the movement of the developer on the developer carrying member on the upstream side in the developer transport direction from the developer peeling member is less likely to act, and the developer of the second developer regulating member It is conceivable that no developer stagnant as planned on the upstream side in the transport direction occurs.

The present invention has been made in view of the above problems, purpose of that is, while maintaining a stable self toner density control, the developer carrying member while preventing the deterioration with time in background contamination and development density It is an object of the present invention to provide a developing device that can perform good development without developing density unevenness in the carrier width direction perpendicular to the developer transport direction and an image forming apparatus including the device .

In order to achieve the above object, the invention of claim 1 includes a developer carrying member having a magnetic field generating means therein and moving on the surface so as to carry and carry a developer containing toner and a magnetic carrier, A first developer regulating member that regulates the amount of the developer carried on the developer carrying member and conveyed toward the developing region; and the conveyance toward the developing region is regulated by the first developer regulating member. A developer containing portion for containing the developer, a toner containing portion having a toner replenishing opening facing the surface of the developer carrying member on the upstream side of the developer carrying direction of the developer containing portion, and the developer carrying member The developer carrying member is carried and transported so that the surface of the developer carrying member rotates around the surface of the developer carrying member from the facing portion facing the toner supply opening of the toner containing portion toward the developer containing portion. And a second developer regulating member that regulates the amount of the developer conveyed above. The gap between the second developer regulating member and the surface of the developer carrying member is such that the transported developer by the second developer regulating member is increased as the toner concentration of the carried developer on the developer carrying member increases. In the developing device that is set so that the amount of restriction is increased, the surface of the developer carrying member is not disposed in the developer accommodating portion between the second developer restricting member and the first developer restricting member. A peeling member that peels off an upper layer portion of the transported developer that is opposed and brought into contact with the surface of the developer carrying body, and is carried and transported by the developer carrying body. The developer that has reached the developer is conveyed so that it passes between the developer carrier and the release member, and the developer carrier side of the release member that is peeled off by the release member. Accommodated development in the developer accommodating portion while moving along the surface on the opposite side Divided into a stripping developer to be mixed with a non-peeling developer and the release developer, and is characterized in that the join with the developer conveyance direction downstream side of the該剥release member in the developer accommodating portion .

In the developing device according to claim 1, the developer carried and conveyed by the developer carrier and reaching the peeling member is conveyed so as to pass between the developer carrier and the peeling member; The developer is separated by the release member and is moved along the surface of the release member opposite to the developer carrier. Among these developers, a developer containing portion of the peeling member at exfoliated developer (hereinafter referred to as "stripping developer".) Is, the developer accommodating section developer contained in (hereinafter "housing development It is called "agent"). By mixing the developer, the toner taken into the developer is agitated and dispersed, and the charging of the toner by frictional charging between the toner in the developer and the magnetic carrier is promoted, and the toner in the transport developer Distribution and charge amount become uniform. A part of the developer in which the release developer and the stored developer are mixed in the developer storage portion is not peeled off by the release member on the developer carrier on the downstream side in the developer transport direction of the release member. The developer transported so as to pass between the developer carrying member and the peeling member (hereinafter referred to as “non-peeling developer”) joins and is carried on the developer carrying member. The developer on the developer carrying member is regulated by the first developer regulating member to have a predetermined layer thickness, and then used for development.
Further, by peeling only the upper layer portion of the transported developer carried and transported on the developer carrier, the influence of the peeling on the transport of the developer on the developer carrier is reduced, and the self- The toner density control is not impaired and is stabilized.

Furthermore, in the developing device according to claim 1 , the second developer regulating member is used, and the toner carrier on which the toner density is stably controlled without being affected by the magnetic force unevenness on the developer carrier. Since the upper layer portion of the transport developer is peeled off by the release member and mixed with the developer stored in the developer storage portion, the toner stirring and dispersion of the transport developer and toner charging are promoted. The agent can be further homogenized.

According to a second aspect of the present invention, in the developing device of the first aspect , a gap between the peeling member and the surface of the developer carrying member is Gh, and the second developer regulating member and the surface of the developer carrying member are When the gap is Gd2, the relationship 0 <Gh <Gd2 is satisfied.

In the developing device according to claim 2, when the gaps Gh and Gd2 satisfy the predetermined relationship, the toner is taken in from the toner storage portion and passed through the restriction position by the second developer restriction member. The upper layer portion of the transport developer reliably comes into contact with the release member and is peeled off.

The invention according to claim 3, in the developing apparatus of claim 1, said magnetic field generating means has no magnetic poles between the position facing the position and the second developer regulating member facing the peeling member It is characterized by this.

In the developing device according to claim 3, the magnetic field generating means does not have a magnetic pole between a position facing the peeling member and a position facing the second developer regulating member. The developer flow is such that the developer contained in the developer is drawn toward the gap between the second developer regulating member and the surface of the developer carrying member regardless of the toner concentration of the developer. Does not occur. Accordingly, a phenomenon that a part of the developer protrudes from the gap to the toner supply port side due to the flow of the developer does not occur even though the toner concentration of the developer is not increased, is prevented. When the toner concentration of the transport developer on the carrier is lowered, the toner is properly taken into the developer.

According to a fourth aspect of the present invention, in the developing device according to the third aspect , the magnetic flux density on the surface of the developer carrier is from the position facing the second developer regulating member to the position facing the peeling member. The magnetic flux density is such that the developer can be carried on the surface of the developer carrying member by a magnetic force.

In the developing device according to claim 4, the developer is continuously supported on the surface of the developer carrying member even in a section before peeling from a position facing the second developer regulating member to a position facing the peeling member. Therefore, the self toner density control utilizing the movement of the developer accompanying the developer conveyance on the developer carrying member is stabilized.

According to a fifth aspect of the present invention, in the developing device according to the first, second, third, or fourth aspect , the peeling member is a roller-shaped rotating member, and the surface of the developer carrying member is opposed to the developer carrying member. Rotation driving means for rotating the peeling member so as to move in the opposite direction to the surface is provided.

In the developing device according to the fifth aspect , the upper layer portion of the developer on the developer carrying member is dammed and peeled off by the peeling member that is rotationally driven in the predetermined direction in the developer containing portion. The peeled developer is rotated along with the surface movement of the peeling member, moves away from the surface of the developer carrying member, and is mixed with the contained developer in the developer containing portion. Here, since the roller-like rotating member is used as the peeling member, even when the peeling member rotates, the gap between the peeling member and the developer carrying member surface becomes constant, and the developer carrying member is removed from the developer carrying member. The upper layer portion can be peeled off without unevenness in the developer transport direction.

According to a sixth aspect of the present invention, in the developing device according to the fifth aspect , the peeling member is made of a magnetic material.

7. The developing device according to claim 6 , wherein the separation member is magnetized by the magnetic field when the magnetic field generated by the magnetic field generating unit reaches the separation member formed using a magnetic material. It becomes possible to attract and carry the developer by magnetic force. By supporting the upper layer portion of the developer on the developer carrying member with a magnetic force with this peeling member, the developer can be more reliably peeled off.

A seventh aspect of the invention is the developing device according to the sixth aspect , wherein the peeling member is supported at both ends in a direction crossing a developer conveying direction on the developer carrying member. The diameter of the central part in the crossing direction is smaller than the diameters of both end parts.

In the developing device according to claim 7 , even if the central portion of the peeling member is bent toward the developer carrying member by the magnetic force generated by the magnetic field generated by the magnetic field generating unit, the central portion and both ends of the peeling member are In the meantime, unevenness in the gap between the surface of the peeling member and the surface of the developer carrying member can be suppressed.
In addition, it is preferable that the diameter of the peeling member is set so as to continuously change from the center portion to the both end portions according to the amount of bending of the peeling member.

According to an eighth aspect of the present invention, in the developing device according to the first, second, third, or fourth aspect , the peeling member extends along a direction intersecting a developer transport direction on the developer carrier and is magnetic. A rotation driving means for rotating the peeling member so as to move in the direction opposite to the surface of the developer carrying member at a portion facing the developer carrying member. It is a feature.

In the developing device according to claim 8, since the peeling member including the magnetic body rotates in the predetermined direction in the developer accommodating portion, the upper layer portion of the developer on the developer carrier is attracted by the peeling magnetic force with the peeling member. And the developer can be peeled off more reliably.

A ninth aspect of the present invention is the developing device according to the first, second, third, or fourth aspect , wherein the peeling member extends along a direction intersecting a developer transport direction on the developer carrier and has a surface. And a rotation driving means for rotating the peeling member so that the surface moves in a direction opposite to the surface of the developer carrying member at a portion facing the developer carrying member. It is characterized by that.

In the developing device according to claim 9 , when the peeling member having a magnetic pole magnetized on the surface thereof in the developer accommodating portion rotates in the predetermined direction, the magnetic pole on the surface of the peeling member and the magnetic field generating means in the developer carrying body. Since the distance to the magnetic pole changes, the force for attracting the developer peeled from the developer carrying member changes with the rotation of the peeling member, and the mixing of the developer becomes active.

The invention of claim 1 0, in the developing apparatus of claim 9, the rotation member of the peeling member is roller-shaped, the surface of the該剥release member, which is characterized in that the magnetic pole has a plurality magnetized It is.

The developing device according to claim 1 0, because of the use of roller-shaped rotary member as the peeling member, the interval between該剥release member surface and the developer carrying member surface is constant even該剥release member is rotated Therefore, the developer can be peeled off from the developer carrying member without unevenness. In addition, since a plurality of magnetic poles are provided on the surface of the peeling member, there are a plurality of portions that strongly attract the developer on the surface of the peeling member. Therefore, when the peeling member rotates, the magnetic force applied to the developer existing around the peeling member changes, and the mixing of the developer becomes more active.

The invention of claim 1 1, in the developing apparatus according to claim 1 0, said plurality of magnetic poles, is characterized in that is obtained by alternately magnetized to S poles and N poles.

The developing device according to claim 1 1, the so S pole and N pole on the peeling member surface is alternately magnetized, the stronger the force to attract the developer to the surface of the該剥release member, the developer carrying member The developer can be reliably peeled off, and mixing of the developer becomes more active.

The invention of claim 1 2, in the developing apparatus of claim 1 1, the plurality of magnetic poles, respectively, characterized in that it is magnetized in a straight line along the extending direction of the rotation axis of the該剥release member Is.

In the developing device according to claim 12, the developer is supported in a convex shape on the surface of the peeling member so as to extend along the rotation axis direction of the peeling member. The convex developer carried so as to extend in the rotation axis direction of the peeling member moves in the circumferential direction as the peeling member rotates, and gives a moving force to the developer in the developer accommodating portion. Therefore, mixing of the developer becomes more active.

The invention of claim 1 3, in the developing apparatus according to claim 1 0, in the extending direction of the axis of rotation of the release member in the circumferential direction of the S pole and N pole further pole groups alternating該剥release member surface The plurality of magnetic poles are magnetized so as to be arranged in a plurality.

The developing device according to claim 1 3, across the surface of the peeling member, the developer is carried on uneven mixing of the developer becomes more active.

The invention of claim 1 4, in the developing device according to claim 5, 6,7,8,9,10,11,1 2 or 1 5, the rotary drive means, to change the rotational speed of the peeling member And can be driven to rotate.

The developing device according to claim 1 4, it becomes possible to perform the frictional charging between the developer occurs between the該剥release member and the developer carrying member according to the amount of toner taken into the developer, the developer It becomes possible to avoid unnecessary mixing.

The invention of claim 1 5, in the developing device according to claim 1 4, based on the image ratio in the development target of the image, and characterized in that a control means for controlling the rotation driving means.

In the developing device according to claim 15 , toner consumption can be obtained from the image ratio, and the linear velocity of the peeling member can be changed in accordance with the toner consumption. Therefore, proper toner charging according to toner consumption can be performed, and deterioration of the developer can be prevented by avoiding unnecessary mixing of the developer.

The invention of claim 1 6, in the developing device according to claim 1 4, control for controlling the temperature measuring means for measuring the temperature in the apparatus, the rotary drive means based on the temperature measurement result of the temperature measuring means Means are provided.

In the developing device according to claim 16 , when the temperature of the developer is high, proper toner charging is more stable by changing the linear velocity of the peeling member in consideration of an increase in the degree of aggregation of the toner. Can be done. On the other hand, when the temperature of the developer is low, it is possible to reduce the linear velocity of the peeling member to avoid unnecessary mixing of the developer and prevent the developer from deteriorating.

The invention of claim 1 7, in the developing apparatus according to claim 1 6, control for controlling the humidity measuring means for measuring the humidity in the apparatus, the rotary drive means on the basis of the humidity measurement results of said humidity measuring means Means are provided.

In the developing device according to claim 17 , when the humidity of the developer is high, proper toner charging is more stable by changing the linear velocity of the peeling member in consideration of an increase in the degree of aggregation of the toner. Can be done. On the other hand, when the humidity of the developer is low, it is possible to reduce the linear velocity of the peeling member to avoid unnecessary mixing of the developer and to prevent deterioration of the developer.

The invention of claim 18, in the developing device according to claim 5, 6,7,8,9,10,11,1 2 or 1 3, and wherein a surface of the peeling member is machined roughened To do.

In the developing device according to claim 18 , by using a release member having a roughened surface, the developer scraping function and the holding function of the developer by the release member can be enhanced. The upper layer portion of the developer can be reliably peeled off and transported.

According to a nineteenth aspect of the present invention, in the developing device according to the sixth or seventh aspect , the peeling member is made of a magnetic material and faces a peak position of a normal direction magnetic flux density distribution on the surface of the developer carrying member. It is characterized by this.

In the developing device according to claim 19 , since the peeling member is provided so as to face the peak position of the normal direction magnetic flux density distribution on the surface of the developer carrier, the peeling member is easily magnetized. The conveyance force by the peeling member is maximized, and the developer is effectively mixed in the developer accommodating portion.

The invention of claim 2 0, in the developing apparatus of claim 19, normal magnetic flux density at the surface opposite is at least 5mT the side opposed to the developer bearing member on the peripheral surface of the stripping member It is characterized by this.

For claimed in the developing device of claim 2 0, which also the surface of the release member in the developer carrying member opposite to the side opposite to the side of the peeling member can be conveyed reliably carrying a developer by a magnetic force The developer can be mixed more effectively.

A twenty- first aspect of the present invention is the developing device according to the first , second, third, or fourth aspect , wherein the peeling member is a grid-shaped flat plate.

The developing device according to claim 2 1, part of the developer accommodating portion of the grid-shaped developer carrier on the developer having reached the separating member made of a flat plate so as to pass through the grid holes of該剥release member Move and peel from the developer carrying member. Since this grid-shaped flat plate can be installed in a space close to the surface of the developer carrier, a space where the developer can freely move is secured at a position away from the surface of the developer carrier in the developer container. it can. Therefore, the movement of the developer in the developer accommodating portion is not hindered.

According to a twenty-second aspect of the present invention, there is provided a latent image forming means for forming a latent image on a latent image carrier, a developing device for developing a latent image on the latent image carrier to form a toner image, and the latent image carrier. An image forming apparatus provided with a transfer device for transferring the toner image on the transfer material to the transfer material, characterized in that the developing device according to any one of claims 1 to 21 is provided as the developing device.

23. The image forming apparatus according to claim 22, wherein the developing device is used to develop the latent image on the latent image bearing member, thereby forming an image free of background contamination and density reduction and density unevenness in the image width direction. be able to.

According to the first to twenty- first aspects of the present invention, while maintaining a stable self-toner density control function, it is possible to prevent background contamination and a decrease in development density with time and to be orthogonal to the developer transport direction on the developer carrier. Thus, it is possible to perform good development without developing density unevenness in the width direction of the carrier . Further, the toner density can be more stably controlled without being affected by magnetic force unevenness on the developer carrier. In addition, since the stirring and dispersion of the toner and the toner charging of the developer on the developer carrying member are promoted, there is an effect that the developer can be further uniformized.

In particular, according to the second aspect of the present invention, the upper layer portion of the transported developer on the developer carrier that has passed the restriction position by the second developer restriction member is reliably brought into contact with the peeling member and peeled off. There is an effect.

In particular, according to the third aspect of the present invention, a part of the developer is caused by the abnormal flow of the developer that is attracted toward the gap between the second developer regulating member and the surface of the developer carrying member. A phenomenon that protrudes from the gap to the toner supply port side does not occur. Therefore, there is an effect that the toner is properly taken into the developer when the toner concentration of the transport developer on the developer carrier is lowered.

In particular, according to the invention of claim 4, the self-toner density control function using the movement of the developer accompanying the developer conveyance on the developer carrying member is not deteriorated and is further stabilized and is peeled off by the peeling member. There is an effect that the amount of the developer does not change greatly, and the developer can be stably mixed in the developer accommodating portion.

In particular, according to the invention of claim 5 , there is an effect that the upper layer portion of the developer can be stably peeled from the developer carrying member.

In particular, according to the inventions of claims 6 and 8 , there is an effect that the developer can be more reliably peeled off by the peeling member.

In particular, according to the invention of claim 7 , unevenness in the gap between the surface of the peeling member and the surface of the developer carrying member can be suppressed between the central portion and both ends of the peeling member, and the developer carrying There is an effect that the upper layer portion of the developer can be more stably peeled from the body.

In particular, according to the invention of claim 9, 1 2 and 1 3, there is an effect that it is possible to perform actively the mixing of the developer.

In particular, according to the first aspect of the invention 0 and 1 1, it is possible to more stably peeled off the upper portion of the developer from the developer carrying member, that can be carried out actively mixing of the developer effective.

In particular, according to the invention of claim 1 4 to 1 7, strive to optimize the toner charge of the developer carrying member of the developing agent, there is an effect that it becomes possible to prevent the further premature deterioration of the developer .

In particular, according to the eighteenth aspect of the present invention, the developer scraping function and the holding function of the developer by the peeling member are enhanced, so that the upper layer portion of the developer on the developer carrying member is surely peeled and conveyed by the peeling member. There is an effect that can be.

In particular, according to the nineteenth aspect of the invention, the peeling member made of a magnetic material is easily magnetized, and the conveying force by the peeling member is maximized, so that the developer is effectively mixed in the developer accommodating portion. There is an effect that can be.

In particular, according to the present invention 2 0, it is possible to convey reliably carrying a developer by a magnetic force to the peeling member, there is an effect that it is possible to more effectively carry out the mixing of the developer .

In particular, according to according to claim 2 1 of the invention, with a simple configuration, the developer were detached scooped upper portion of the bearing member of the developer, the developer carrying member of the developer and the developer containing portion of the developer Can be reliably mixed . Furthermore , since a space where the developer can freely move is secured at a position away from the surface of the developer carrying member in the developer accommodating portion, there is an effect that the movement of the developer in the developer accommodating portion is not hindered. .

According to the twenty-second aspect of the present invention, there is an effect that it is possible to form an image free from background smear and density reduction and image density unevenness in the image width direction.

Embodiment 1
A first embodiment in which the present invention is applied to a developing device of a laser printer (hereinafter referred to as “printer”) which is an electrophotographic image forming apparatus will be described.
First, the outline of the printer according to the present embodiment will be described with reference to FIG. The photosensitive drum 1 as a latent image carrier is uniformly charged by a charging roller 50 that contacts the photosensitive drum 1 and charges its surface while being rotated in the direction of arrow A in the figure, and then optical writing is performed. The unit 51 performs scanning exposure based on the image information to form an electrostatic latent image on the surface. In this embodiment, the latent image forming unit is configured by the charging roller 50 and the optical writing unit 51. However, other types of charging devices and exposure devices may be used. The electrostatic latent image formed on the photosensitive drum 1 is developed by a developing device 2 described later, and a toner image is formed on the photosensitive drum 1. The toner image formed on the photosensitive drum 1 is transferred from a paper feed cassette 54 through a paper feed roller 55 and a resist roller pair 56 by a transfer unit having a transfer roller 53 as a transfer device. 52 is transferred onto 52. After the transfer, the paper 52 is fixed with a toner image by the fixing unit 57 and discharged outside the apparatus. The residual toner on the photosensitive drum 1 that has not been transferred is removed from the photosensitive drum 1 by the cleaning unit 58. Further, the residual charge on the photosensitive drum 1 is removed by the charge eliminating lamp 59.

Next, the overall configuration of the developing device according to the present embodiment will be described.
FIG. 3 is a schematic configuration diagram of the entire developing device 2, and FIG. 1 is an enlarged view of a main part of the developing device 2. The developing device 2 is disposed on the side of the photosensitive drum 1 and has a two-component developer (hereinafter referred to as “developer”) 3 including a toner 3a and a magnetic carrier (hereinafter referred to as “carrier”) on the surface. A developing sleeve 4 made of a nonmagnetic material is provided as a developer carrying member to be carried. The developing sleeve 4 is attached so as to be partially exposed from an opening formed on the photosensitive drum 1 side of the casing 2a, and the developer is lowered in a developing region facing the photosensitive drum 1 by a driving device (not shown). It can be rotationally driven in the direction of movement in the direction of arrow B in the figure. Further, a magnet roller 5 composed of a fixed magnet group as a magnetic field generating means is fixedly arranged inside the developing sleeve 4.

  Further, the developing device includes a doctor 6 as a developer regulating member that regulates the amount of developer carried on the developing sleeve 4 and conveyed toward the developing region, and the doctor 6 on the upstream side in the developer conveying direction. A developer accommodating case 7 provided so as to form a developer accommodating portion S for accommodating the developer 3 between the surface of the developing sleeve 4 and the doctor 6, a toner hopper 8 as a toner accommodating portion, and the like are also provided. The toner hopper 8 has a toner replenishing opening (hereinafter referred to as “toner replenishing port”) 8 a adjacent to the upstream side of the developer accommodating portion S in the developer transport direction on the developing sleeve 4 and facing the surface of the developing sleeve. Yes. Further, inside the toner hopper 8, a toner agitator 9 is disposed as a toner agitating member that sends out the toner 3a while agitating the toner 3a toward the toner supply port 8a while rotating in the clockwise direction indicated by an arrow C in the drawing.

  A tip portion (eave portion) of the developer containing case 7 adjacent to the developing sleeve 4 is a second portion that regulates the amount of developer that is replenished with toner from the toner hopper 8 and proceeds toward the developer containing portion S. It is used as a predoctor 7a as a developer regulating member. Further, in the developer accommodating portion S formed by the developer accommodating case 7 or the like, the developer that is not supplied to the developing area facing the photosensitive drum 1 but is prevented from advancing by the doctor 6 is accommodated. .

A plurality of magnetic poles extending in the direction along the central axis direction of the roller are formed on the surface portion of the magnet roller 5. Specifically, the main pole (N1 pole) is formed at a position facing the developing area, and the magnetic field of the magnetic field is applied to the developer accommodating portion S, from the position facing the predoctor 7a to the developing area. The magnetic pole (S2 pole) is arranged on the top. Further, on the surface of the magnet roller 5, similarly to a general developing device, conveying magnetic poles (S pole, N pole) for carrying the developer on the developing sleeve 4 while being carried are appropriately disposed. Yes.
In the present embodiment, a fixed magnet body, that is, a so-called block-type magnet roller in which a magnet piece is fitted and fixed to a base material is used. However, the present invention is not limited to this. For example, it is a matter of course that a so-called ferrite-based integral plastic magnet roller produced by magnetizing a plastic magnet material molded into a predetermined shape simultaneously with magnetic orientation may be used.

Further, in the developing device, a part of the developer (surface layer portion of the transported developer) that is opposed to the surface of the developing sleeve 4 in a non-contact manner in the developer accommodating portion S and is carried and transported to the developing sleeve 4. As a peeling member to be peeled off, a peeling roller 11 which is a roller-like rotating member formed of a magnetic material is provided. The peeling roller 11 may be cylindrical or columnar, and the internal structure is not limited to a specific structure.
As a material (magnetic material) of the peeling roller 11, for example, a SUM material (sulfur and sulfur composite free-cutting steel material), a magnetic SUS material, iron, nickel, or the like can be used. In addition, an iron core nickel-plated, a stainless steel material coated with a magnetic material, or the like can also be used.
Further, the surface of the peeling roller 11 is preferably roughened by sandblasting or the like so that the developer peeled off from the developing sleeve can be satisfactorily carried and conveyed. For example, roughening is performed so that the surface roughness (10-point average roughness Rz) is about 30 μm. This surface roughness is set to such an extent that the toner can be conveyed according to conditions such as the type of toner and the material of the peeling roller.

  The peeling roller 11 is rotationally driven in the same rotational direction as the developing sleeve 4 (in the direction of arrow E in the figure) by a driving device (not shown). By this rotational driving, the surface of the peeling roller 11 moves in a direction opposite to the surface of the developing sleeve at the facing portion between the developing sleeve 4 and the peeling roller 11, so that the upper layer of the developer on the developing sleeve 4 by the peeling roller 11. The part can be dammed and peeled off reliably. Then, the peeled developer is rotated along with the surface movement of the peeling roller 11, moves away from the surface of the developing sleeve, and is mixed with the developer stored in the developer accommodating portion S.

Further, the magnetic pole (S2) of the magnet roller 5 at a position facing the developer accommodating portion S is not arranged between a position facing the peeling roller 11 and a position facing the predoctor 7a. In this embodiment, as shown in FIG. 4, the inclination angle θ of the line connecting the center of the magnet roller 5 and the magnetic pole (S2) with respect to the line connecting the center of the magnet roller 5 and the center of the peeling roller 11 is 2. The formation position of the magnetic pole (S2) was set to be about -10 °.
In this way, by not arranging the magnetic pole between the position facing the peeling roller 11 and the position facing the pre-doctor 7a, the developer stored in the developer storage section S becomes the developer toner. Regardless of the density level, an abnormal flow of the developer that is attracted toward the gap between the predoctor 7a and the developing sleeve surface does not occur.

  As shown in FIG. 4, the gap Gh between the peeling roller 11 and the developing sleeve surface and the gap Gd2 between the predoctor 7a and the developing sleeve surface are set so as to satisfy the relationship of 0 <Gh <Gd2. preferable. By setting the gaps Gh and Gd2 in this way, the upper layer portion of the transported developer on the developing sleeve 4 that has taken in the toner from the toner hopper 8 and passed the restriction position by the pre-doctor 7a is surely brought into contact with the peeling roller 11. Is peeled off.

When the peeling roller 11 made of the magnetic material is used, a magnetic pole is generated on the surface of the peeling roller 11 by the magnetic action of the magnet roller 5 in the developing sleeve 4, and the developer on the developing sleeve 4 is efficiently produced. 3 can be peeled off. However, the magnetic force acting on the peeling roller 11 is bent so that the central portion in the axial direction of the peeling roller 11 approaches the developing sleeve 4 side, and the distance from the developing sleeve 4 becomes narrower than the target interval. There is a case.
Therefore, when the above-described bending occurs, it is preferable to make the diameter D2 of the central portion of the peeling roller 11 smaller than the diameter D1 of both ends as shown in FIG. By using this peeling roller 11, the distance between the peeling roller 11 and the developing sleeve 4 can be made substantially uniform over the entire axial direction. Accordingly, a uniform peeling operation can be performed from the central portion to both end portions.
When the bending does not occur, as the peeling member, a straight bar-like peeling roller having a circular cross section with a constant diameter over the entire axial direction may be used.

Next, the developing operation of the developing device having the above configuration will be described with reference to FIGS.
The developer 3 on the developing sleeve 4 is conveyed as the sleeve 4 rotates in the direction of arrow B, and is regulated by the doctor 6 to be thinned. The thinned developer 3 is conveyed to a developing area facing the photosensitive drum 1 rotating in the direction of arrow A. In this developing area, toner is supplied to the electrostatic latent image formed on the photosensitive drum 1, and the electrostatic latent image is visualized. The developer on the developing sleeve 4 that has passed through the developing region is further transported as the sleeve 4 rotates, and reaches a position facing the toner supply port 8a. In the toner supply port 8a, the toner 3a in the toner hopper 8 is sent out by the agitator 9 and stays in contact with the developer on the developing sleeve 4. After the new toner 3a is taken in at the toner supply port 8a, the process returns to the developer accommodating portion S. The internal pressure of the developer 3 containing the new toner 3 a increases at the restriction portion by the doctor 6. The toner is charged by frictional charging with the carrier in the developer having an increased internal pressure. On the other hand, a part of the developer 3 that is not supplied to the developing area and is prevented from advancing by the doctor 6 moves to circulate in the developer accommodating portion S.

Next, self toner density control during the developing operation in the developing device will be described with reference to FIGS. Note that a two-dot chain line in FIG. 6 indicates an interface between developers exhibiting different behaviors.
First, when a developer having a predetermined toner concentration and weight is set as an initial agent in the developing device and the developing sleeve 4 and the peeling roller 11 are rotationally driven, the developer 3 is transported developer 3b, the housed developer 3c, and the peeling. The developer 3d is divided into three parts. The transport developer 3b is a developer that is carried on the surface of the developing sleeve 4 by a magnetic force and transported so as to follow the surface. The accommodated developer 3c is a developer that is accommodated in the developer accommodating portion S and circulates and moves in the developer accommodating portion S as the transported developer 3b moves. Further, the peeling developer 3 d is a developer that is partially peeled from the transport developer 3 b on the developing sleeve 4 and moves along the surface of the peeling roller 11 as the peeling roller 11 rotates.
In the developer accommodating portion S, four developer flows F1, F2, F3, and F4 are generated as shown in FIG. The first developer flow F <b> 1 is a flow of the transport developer 3 b that flows so as to pass between the developing sleeve 4 and the peeling roller 11. The second developer flow F2 is a circulating flow that is peeled from the developing sleeve 4 and moves along the peeling roller 11, and a part thereof circulates in the space between the peeling roller 11 and the predoctor 7a. The third developer flow F <b> 3 is a flow of the peeling developer 3 d that circulates above the peeling roller 11 along the surface of the peeling roller 11. The fourth developer flow F <b> 4 is a circulating flow of the stored developer 3 c generated in the space between the doctor 6 and the peeling roller 11 as the developer rises behind the doctor at the doctor 6.

  Next, when the toner 3a is set in the toner hopper 8 in a state where the developer flows F1 to F4 are generated in the developer accommodating portion S, the transport development carried on the developing sleeve 4 from the toner supply port 8a. The toner 3a is supplied to the agent 3b. The developer on the developing sleeve 4 to which the toner is supplied is conveyed to the developer accommodating portion S together with the toner. In the middle of conveyance, the toner supplied to the conveyance developer 3 b slightly enters the axial center direction of the development sleeve 4. The transported developer 3b supplied with the toner passes through a regulation position by the pre-doctor 7a, and then the upper layer is peeled off by the peeling roller 11 to become the peeling developer 3d. The release developer 3d is conveyed while being mixed with the housed developer 3c, and a part thereof joins the circulating flow F2 generated in the vicinity of the predoctor 7a. On the other hand, the release developer 3d that is continuously carried by the release roller 11 moves while being mixed with the contained developer 3c, and is again carried and carried on the developing sleeve 4 on the downstream side in the developer conveyance direction. Developer 3b is obtained. By mixing the release developer 3d and the housed developer 3c, the two developers are exchanged, the toner is dispersed and stirred in the developer, and the toner is charged by frictional charging between the toner and the carrier.

Next, as the toner concentration in the developer 3 gradually increases due to the replenishment of the toner, the bulk of the developer 3 increases, so that the restriction position by the doctor 6 from the position facing the toner replenishing port 8a. The thickness of the conveyed developer 3b on the developing sleeve 4 increases in the interval up to. At the same time, the carrier ratio in the transport developer 3b on the developing sleeve 4 is reduced, so that the magnetic force on the transport developer 3b is weakened. Therefore, the moving speed of the transport developer 3b is decreased. The layer thickness of the conveyed developer 3b on the developing sleeve 4 in the above section becomes increasingly thicker. The transport developer 3b having the increased layer thickness is strongly subjected to a force (braking force) in a direction to prevent the transport received from the peeling roller 11, and is transported to the position where the peeling roller 11 is stripped. The moving speed of the developer 3b is further decreased.
Then, the upper layer portion of the transport developer 3b whose layer thickness is increased at a position facing the toner supply port 8a is scraped off by the predoctor 7a, and the developer transport direction of the predoctor 7a as shown in FIG. 6A. It stays upstream. Hereinafter, the staying developer is referred to as “staying developer” 3e. The staying developer 3e is circulated along with the movement of the transport developer 3b in contact therewith. The toner 3a sent to the toner replenishing port 8a is attracted to the exposed portion of the transport developer 3b and is drawn from the junction P between the transport developer 3b and the staying developer 3e. Taken into the developer.

  As the toner concentration of the developer 3 further increases, the amount of staying developer 3e at the toner replenishing port 8a increases as shown in FIG. 6B, and the transport development in contact with the toner by the staying developer 3e. The exposed surface of the developer 3b is blocked, and the joining point P of both developers also moves to the upstream end of the toner supply port 8a in the developer transport direction. At the same time, the circulating movement speed of the staying developer 3e itself at the toner supply port 8a is also reduced. At this point, the toner is almost completely taken into the developer, and the toner density does not increase any more.

  A part (upper layer part) of the transported developer 3 b that has taken in the toner and passed through the gap between the predoctor 7 a and the developing sleeve 4 is peeled off by the peeling roller 11. The release developer 3d is conveyed along the surface of the release roller 11 while being mixed and stirred with the contained developer 3c, and a part of the release developer is carried on the developing sleeve 4 again. The transported developer 3 b that has passed through the gap between the developing sleeve 4 and the doctor 6 is transported to a developing region that faces the photosensitive drum 1. In the developing area, toner is supplied to the electrostatic latent image formed on the photosensitive drum 1 and used for developing the electrostatic latent image.

  When the toner on the developing sleeve 4 is consumed by the development of the electrostatic latent image on the photosensitive drum 1, the toner density in this portion decreases, and the conveying force acting on the developer by the developing sleeve 4 increases. The bulk of the developer in this part is also reduced. Then, the layer thickness of the transport developer 3b regulated by the front end portion of the predoctor 7a is reduced, the amount of the staying developer 3 accumulated near the toner supply port 8a is reduced, and the staying developer 3 is circulated. The speed will also increase. Then, at the toner replenishing port 8a, the transport developer 3b transported by the developing sleeve 4 and the toner 3a from the toner hopper 8 come into contact with each other, and the toner is taken in again and the toner concentration of the developer 3 as described above. Will increase.

  As described above, in accordance with the change in the toner density on the developing sleeve 4, the regulation state of the transport developer on the developing sleeve 4 by the predoctor 7a changes, and the toner of the developer in the portion where the toner is consumed. Self-control is performed so that the density falls within a predetermined density range. As a result, the toner density of the conveyed developer 3 on the developing sleeve 4 is always kept within a substantially constant range. This eliminates the need for complicated toner concentration control mechanisms such as a toner concentration sensor and a toner replenishing member.

  As described above, according to the present embodiment, a part of the transport developer 3b on the developing sleeve 4 is peeled and mixed with the stored developer 3c in the developer storage section S, whereby the transport developer 3b and the storage Since replacement with the developer 3c is promoted, early deterioration of the developer 3 due to a decrease in the charging ability of the carrier in the developer 3 can be prevented. Further, by mixing the transport developer 3b and the stored developer 3c, the toner of the developer is dispersed and stirred, and the toner density becomes uniform in the image width direction perpendicular to the developer transport direction. Good development can be performed.

Further, according to the present embodiment, since the peeling roller 11 having a circular cross-sectional shape is used, even if the peeling roller 11 is rotated, the circumferential surface of the peeling roller 11 and the circumferential surface of the developing sleeve 4 are Since the gap does not change, there is no peeling unevenness when the peeling roller rotates. Therefore, unevenness in toner density and toner charge amount can be suppressed in the transport developer 3b on the developing sleeve 4 in the developer transport direction, and development density unevenness in the developer transport direction can be prevented.
In addition, when an experiment was performed on a peeling member having a cross-sectional shape other than circular, for example, a crank shape, peeling unevenness occurred, and a difference in density (unevenness) occurred in the image at the crank rotation pitch.

  Further, according to the present embodiment, since the separation roller 11 made of a magnetic material is used, the separation roller 11 is magnetized by the magnet roller 5 in the development sleeve 4 and is carried on the development sleeve 4. A part of the transported developer 3b that is rotating can be adsorbed by a magnetic force. Therefore, the developer is peeled off from the developing sleeve 4 and a flow (the flow indicated by the symbol F3 in FIG. 6) for forcibly moving the peeled developer 3d along the surface of the peeling roller is created. Done more prominently. Therefore, mixing and stirring with the developer in the developer accommodating portion S can be performed more efficiently.

In the present embodiment, the rotation of the peeling roller 11 may be controlled based on the image ratio of the image to be printed (original) or the measurement result of the temperature and humidity in the apparatus.
FIG. 7 is a block diagram illustrating an example of a control unit as a control unit of the printer according to the present embodiment. Image data sent from an external device such as a personal computer is processed by the image data processing unit 110. In this image data processing, data for forming a latent image used in the latent image forming unit is generated, and image ratio data of an image to be printed is calculated. An engine control unit 100 that controls each unit in the apparatus based on data sent from the image data processing unit 110 includes an engine control CPU 101, a ROM 102, a RAM 103, an I / O interface 104, and the like. The engine control unit 100 is connected to a photosensitive drum driving unit 105, a latent image forming unit driving unit 106, a driving unit 107 of the developing device 2, a temperature / humidity sensor 108, and the like. The engine control CPU 101 follows the control program read from the ROM 102 and responds to an input signal from the image data processing unit 110 and performs various recognitions and judgments including the operation timings of the various drive units to issue operation commands to the respective units. The output is performed and a predetermined operation is performed. Further, the above-described units can be controlled based on temperature / humidity data detected by a temperature / humidity sensor.

  For example, the control unit controls the rotation of the peeling roller 11 of the developing device 2 based on the image ratio data of the image to be printed. In this case, the linear velocity of the peeling roller 11 can be changed in accordance with the toner consumption that changes in accordance with the image ratio, and proper toner charging can be performed, and the developer can be avoided by avoiding unnecessary mixing of the developer. Can be prevented.

Further, it has been found that the amount of toner 3a taken in varies depending on the degree of aggregation of the toner itself depending on the environment and the like, resulting in a change in transport speed and bulk. It has been found that the aggregation degree of the toner 3a varies depending on the temperature and humidity, and as shown in FIGS. 8 and 9, the aggregation degree increases under a high temperature condition and also increases under a high humidity condition. A high degree of aggregation indicates that the toner 3a is solidified.
Therefore, for example, the ambient temperature in the vicinity of the photosensitive drum 1 is measured by the temperature / humidity sensor 108 provided inside the image forming apparatus main body. By increasing the linear velocity of the developer 3, the developer 3 can be sufficiently mixed and stirred, and the replacement of the developers 3 and frictional charging can be sufficiently promoted. In addition, the humidity inside the image forming apparatus is measured by the temperature / humidity sensor 108, and when the humidity increases, the same drive control as that when the temperature increases is performed, thereby mixing and mixing the developer 3. Stirring can be sufficiently performed to sufficiently promote replacement of the developers 3 and frictional charging.

In the present embodiment, as shown in FIG. 4, the magnetic pole (S2) at the position facing the developer accommodating portion S is arranged slightly shifted toward the doctor 6 side, but this magnetic pole (S2) is generated. You may comprise so that the peak position of normal direction magnetic flux density distribution may correspond in general to the direction of the peeling roller 11. FIG. In this case, the peeling roller 11 is most easily magnetized, and the peeling / conveying force by the peeling roller 11 is maximized. As a result, the developer is effectively frictionally charged between the developing sleeve 4 and the peeling roller 11 in the developer accommodating portion S.
Further, in order to effectively advance the developer circulating operation around the peeling roller 11 in the developer accommodating portion S, the method on the surface opposite to the side facing the developing sleeve 15 on the peripheral surface of the peeling roller 11 is used. The linear magnetic flux density is preferably 5 mT or more.

Further, in order to effectively perform the developer circulation operation around the peeling roller 11 in the developer accommodating portion S, a certain amount of space must always be secured so that the developer can be circulated. For this purpose, it is necessary to stop taking in the toner 3a while there is a space in the developer accommodating portion S. With regard to this point, as a result of intensive studies by the present inventors, the magnetic force received by the developer at a position facing the peeling roller 11 on the developing sleeve 4 is F1, and the developing sleeve 4 is opposed to the predoctor 7a. Assuming that the magnetic force received by the developer 3 at the position is F2, it has been found that these relationships may be set to the conditions shown in the following equation (1).

When F2 becomes relatively large on the developing sleeve 4, the influence of the braking force by the peeling roller 11 does not reach the vicinity of the toner supply port 8a. As a result, even if the developer toner concentration increases, the developer transport speed does not decrease and the layer thickness of the developer 3 does not increase easily. Therefore, the toner is kept until the developer accommodating portion S is filled with the developer. 3a cannot be stopped. Therefore, as shown in the above formula (1), the magnetic force F2 received by the developer at the position facing the predoctor 7a with respect to the magnitude F1 of the magnetic force received by the developer at the position facing the peeling roller 11 Is set relatively weak so that the influence of the braking force by the peeling roller 11 extends to the vicinity of the toner supply port 8a.
Control of the magnetic force waveform may be appropriately performed according to the position, polarity, shape, and magnetic force of the magnet pieces arranged on each pole.

  In this embodiment, the peeling roller 11 which is a roller-like rotating body is used as the peeling member, but the shape of the peeling member is not limited to this. For example, as shown in FIG. 10, a peeling member for scrubbing the developer on the developing sleeve 4 with a peeling surface in almost the entire longitudinal direction (direction along the rotation axis of the developing sleeve) in the developer accommodating portion S. 10 is provided. In this case, the rake angle θ of the peeling surface 10a of the peeling member 10 with respect to the tangent to the surface of the developing sleeve is preferably 90 degrees or more so that the developer can be efficiently peeled without retaining the developer. . Due to the peeling surface of the peeling member 10, the upper layer portion of the conveyed developer 3 b that is carried on the developing sleeve 4 rotating in the counterclockwise direction in the drawing is peeled off, as shown by the locus of the arrow D. Developer flow occurs. Due to the flow of the release developer, mixing and stirring of the developer released from the developing sleeve 4 and the developer in the developer accommodating portion S can be promoted. A part of the developer that has been mixed and stirred is carried on the developing sleeve 4 by a magnetic force between the peeling member 10 and the doctor 6.

(Example 1)
Next, more specific examples of the developing device according to this embodiment will be described.
Using the developing device shown in FIG. 3, first, as shown in FIG. 11, black and white are alternately arranged in the longitudinal direction (image width direction) orthogonal to the surface movement direction (G direction in the drawing) of the developing sleeve 4 so that the toner consumption is different. The formed test chart 60 was used as an image to be printed, and 20 images were formed. Thereafter, image formation was again performed using a test chart composed of uniform halftones on the entire surface. Experimental conditions were set within the range shown in Table 1. For example, a peeling roller 11 having a diameter of 7 mm is used, the gap Gp between the developing sleeve 4 and the photosensitive drum 1 is 0.35 mm, the gap Gd1 between the developing sleeve 4 and the doctor is 0.4 mm, and the developing sleeve 4 and the pre-doctor 7a. Is set to 0.65 mm, and the gap Gh between the peeling roller 11 and the developing sleeve 4 is set to 0.35 mm.

As a result of the above-described image formation experiment conducted under the above conditions, the developer is peeled off by the peeling roller 11 and the developer is mixed and stirred, the developer is made uniform, and a good image without density unevenness can be obtained. It was. In the developing device of this embodiment, the gap Gh between the peeling roller 11 and the developing sleeve 4 and the gap Gd2 between the developing sleeve 4 and the pre-doctor 7a satisfy the relationship of the following expression (2). Good stirring ability was obtained.

  When the material of the peeling roller 11 is a magnetic material (for example, SUM material), the central portion of the peeling roller 11 is located under the condition that the normal direction magnetic flux density on the developing sleeve 4 facing the peeling roller 11 is 56 mT. It turned out that it bends so that it may approach about 0.1 mm at the developing sleeve 4 side. Therefore, in this embodiment, the shape of the peeling roller 11 is set so that the diameter D2 (= 6.8 mm) at the center is smaller than the diameter D1 (= 7 mm) at both ends as shown in FIG. By using the peeling roller 11 having such a shape, the distance between the peeling roller 11 and the developing sleeve 4 can be maintained at approximately 0.35 mm in the axial direction, and the developer is provided from the center to both ends. Peeling and subsequent mixing and stirring could be performed uniformly.

(Comparative Example 1)
On the other hand, as a comparative example of this example, when the above-described image formation was performed with a conventional developing device that did not use the peeling member 12, density unevenness occurred in the halftone image. As described above, when a chart composed of alternating black and white with different toner consumption in the longitudinal direction of the developing sleeve 4 is used unless the peeling member 12 is used, the toner density in the longitudinal direction becomes non-uniform and the image deteriorates. There was a case.

[Embodiment 2]
FIG. 12 is a front view showing a schematic configuration of a printer according to the second embodiment of the present invention, and FIG. 13 is a cross-sectional view showing a schematic configuration of a developing device of the printer. In FIGS. 12 and 13, parts similar to those of the printer according to the first embodiment (FIGS. 2 and 3) are denoted by the same reference numerals, and their functions are also the same. Those explanations are omitted. In addition, the alternate long and short dash line shown around the developing sleeve 4 in FIGS. 12 and 13 indicates the distribution of the normal direction component of the magnetic flux density on the surface of the developing sleeve 4.

  In this embodiment, the peeling roller 11 made of a magnetic material is used in the first embodiment, but the peeling roller 13 made of a magnet roller having a magnetic pole magnetized in advance and having a magnetic force is used as a peeling member. ing. Further, in the developing device of the present embodiment, a protruding portion 2b having a facing surface 2c is formed at the bottom of the casing 2 near the toner supply port 8a. The facing surface 2c is formed with a predetermined length so as to incline downward from the toner hopper 8 side toward the developing sleeve 4 side. In addition, there is a difference in the structure of the toner hopper 8, but the description thereof is omitted because it is not relevant to the present invention.

FIG. 14 is a cross-sectional view of a developing device in which FIG. 11 is partially simplified to show an example of the peeling roller 13 made of the magnet roller.
In this developing device, a peeling roller 13 having a pair of magnetic poles (S pole and N pole) magnetized on the surface so as to extend along the rotation axis is used, at a position facing the magnetic pole 5 a in the developing sleeve 4. The rotation is the same as in the first embodiment. When the peeling roller 13 is used, it is possible to strongly adsorb the developer 3 carried and carried on the developing sleeve 4 by a magnetic force. Therefore, the peeling of the developer from the developing sleeve 4 and the forced flow are more remarkably performed, and the mixing and stirring with the developer in the developer accommodating portion S can be performed more efficiently.

  FIG. 15 is a cross-sectional view of a developing device including a peeling roller 14 made of a magnet roller according to a modification. The peeling roller 14 used in this developing device has a configuration in which a plurality of magnetic poles are alternately magnetized on the outer peripheral surface. The peeling roller 14 according to the modification of FIG. 15 has a configuration in which four pairs of S poles (14a) and N poles (14b) are magnetized. The peeling roller 14 is rotatably disposed at a position facing the south pole 5a of the magnet roller (magnet) 5 disposed inside the developing sleeve 4. Then, when the peeling roller 14 rotates and the S pole arranged on the peripheral surface approaches the S pole 5a of the magnet roller 5, the developer 3 between the peeling roller 14 and the developing sleeve 4 receives a force to be discharged. Subsequently, when the N pole of the peeling roller 14 approaches, the developer 4 between the peeling roller 14 and the developing sleeve 5 receives an attractive force. As described above, the repulsive force and the attractive force are alternately repeated in the narrow space between the developing sleeve 4 and the peeling roller 14, so that the mixing / stirring in the developer 3 becomes more active and the toner density is made uniform. In addition, the magnetic force of the magnetic poles alternately magnetized on the peeling roller 14 attracts a part of the developer 3 to the peeling roller 14 at portions other than the vicinity of the developing sleeve 4, and has the effect of further increasing the stirring force. As a result, the toner distribution can be more effectively uniformed, and abnormal images such as density unevenness can be prevented.

  As shown in the perspective view of FIG. 16, a plurality of magnetic poles having substantially the same length as the axial direction of the peeling roller 14 are configured by alternately magnetizing S poles and N poles in the axial direction. Also good. In this case, when the developer 3 adheres to the surface of the peeling roller 14, unevenness of the developer is formed on the surface, and the same stirring effect can be obtained as in the case of using a member having unevenness on the surface.

FIG. 17A is a perspective view of a peeling roller 15 according to another modification. The peeling roller 15 has a configuration in which a magnetic pole having a certain length is alternately magnetized with an S pole (15a) and an N pole (15b) in the axial direction. When the developer adheres to the peeling roller 15, in addition to the stirring effect by the peeling roller 14 shown in FIG. 16, the stirring mechanism works between the magnetic poles alternately arranged in the axial direction. Stirring can be performed.
Further, as in the peeling roller 16 shown in FIG. 17B, the magnetic poles in the axial direction may be slightly separated from each other, and the magnetic poles may be magnetized as in the peeling roller 17 shown in FIG. The same effect can be obtained even if they are arranged slightly shifted in the axial direction so that the same poles partially overlap in the circumferential direction.

(Example 2)
Next, a more specific example of the developing device 2 according to this embodiment will be described.
Using the developing device 2 shown in FIG. 15, the test chart 60 in which the belt-like black portions and white portions shown in FIG. 11 are alternately repeated is used as an image to be printed, and 20 images are formed. The toner was consumed locally. Thereafter, an entire halftone image (ID of about 0.2 to 0.5 with a reflection density measuring device) was formed, and rank evaluation of density unevenness level was performed. The development conditions were set as shown in Table 2 below.
FIGS. 18A to 18E are views showing the ranks of the density unevenness levels, and show the full-tone halftone images formed on the paper 52 with different levels of the residual black portions 52a. 18 (a) is rank 2, FIG. 18 (b) is rank 3, FIG. 18 (c) is rank 3.5, FIG. 18 (d) is rank 4, and FIG. 18 (e) is rank 5. The higher the rank, the less the density unevenness. Rank 3 in FIG. 18B corresponds to the case of the device according to the conventional example.

  As a result of conducting the above-mentioned image formation experiment several times under the above conditions, it was confirmed that the density unevenness was improved. Table 3 shows the evaluation results.

  In the configuration of the peeling roller 14 shown in FIG. 16, the rank is 3 to 3.5, and in the configuration of the three peeling rollers 15, 16, and 17 shown in FIGS. 17 (a) to (c), the rank is 3.5 to 4. It was confirmed that there was an effect on density unevenness.

  In addition, as a result of repeated investigations by the present inventors with respect to the developing device of the present embodiment, the circulating operation of the developer 3 is effectively caused around the peeling roller, and the frictional charging between the developers 3 is sufficiently promoted. Therefore, it was found that the ratio between the linear velocity of the developing sleeve 4 and the linear velocity of the peeling roller 14 is important. Therefore, as the driving means for the peeling roller 14, an independent variable driving means (not shown) that can be rotationally driven by changing the linear speed of the peeling roller 14 is provided in the driving portion of the developing device, and the variable driving means is provided. You may comprise so that it may control by the engine control part 100 shown in the said FIG. As this variable drive means, for example, a stepping motor can be provided in the drive source. The drive source is not limited to a stepping motor, and an AC motor, a servo motor, or the like can be used.

  In order to confirm the influence of the ratio between the linear velocity of the developing sleeve 4 and the linear velocity of the peeling roller 14, image formation was performed under the development conditions shown in Table 4 while changing the linear velocity ratio. .

As a result of image formation performed under the above conditions, assuming that the linear velocity of the developing sleeve 4 is S [mm / s] and the linear velocity of the peeling roller 14 is T [mm / s], the ratio ε = (T / S ) Is set so as to satisfy the relationship of the following expression (3), the developer 3 is effectively frictionally charged between the developing sleeve 4 and the peeling roller 14 in the developer accommodating portion S. I understood it.

  This is because the amount of the carrier to be set is constant, so that at least the ratio of the linear velocity of the developing sleeve 4 and the linear velocity of the peeling roller 14 is within the above range, the amount of toner taken in becomes an appropriate amount. This is because the conveyance speed and bulk of the toner on the sleeve 4 change so that frictional charging is effectively performed.

Further, in the developing device of this embodiment, it has been found that the amount of toner 3a taken up also changes due to the difference in the degree of aggregation of the toner itself depending on the environment and the like, resulting in changes in the conveyance speed and bulk. The aggregation degree of the toner 3a varies depending on the temperature and humidity, and as shown in FIGS. 8 and 9, it is known that the aggregation degree becomes high under a high temperature condition and also becomes high under a high humidity condition. A high degree of aggregation indicates that the toner 3a tends to harden.
Therefore, for example, a temperature sensor (not shown) for measuring the ambient temperature in the vicinity of the photosensitive drum 1 is provided in the main body of the image forming apparatus. By increasing the rotational speed and increasing the linear speed of the peeling roller 14, the developer 3 can be sufficiently mixed and stirred, and the frictional charging between the developers 3 can be sufficiently promoted.
Similarly, a humidity sensor (not shown) is provided inside the image forming apparatus, and when the humidity becomes high, the same drive control as in the case of using the temperature sensor is performed, so that the developer 3 is mixed. -Thorough stirring can be performed to sufficiently promote frictional charging between the developers 3.

  Further, in a digital image forming apparatus such as the printer of this embodiment, the consumption of the toner 3a is obtained by obtaining the image ratio from the image signal accompanying writing, and the line of the peeling roller 14 is matched to the toner consumption. It is possible to change the speed. Specifically, when an image with a high image ratio is formed and the toner density is lowered, the toner supply is increased, so that triboelectric charging needs to be performed more actively. Control to raise. On the other hand, when an image with a low image ratio is formed and the toner 3a is consumed less and the toner density is kept constant, the triboelectric charging is positively performed to prevent the developer 3 from being deteriorated. Since there is no need, control is performed to maintain the linear speed of the peeling roller 14 as it is or to decrease the linear speed.

  Further, when the linear speed of the peeling roller 14 is increased and the ratio ε becomes 1.5 or more, not only the deterioration of the developer 3 is accelerated, but also the incorporation of the developer 3 into the developer storage portion S is restricted, and the toner It was found that the density was lower than the target toner density. On the other hand, when the linear speed of the peeling roller 14 was decreased and the ratio ε was 0.5 or less, there was no mixing / stirring effect, and replenishment unevenness was confirmed on the image.

  The above control can also be applied to the case where the peeling rollers 15, 16, and 17 mentioned as the above modification are used, and the same effect can be obtained.

[Embodiment 3]
FIG. 19 is a cross-sectional view showing a schematic configuration of a developing device according to the third embodiment of the present invention. In FIG. 19, the same parts as those in FIGS. 1 and 3 in the first embodiment are denoted by the same reference numerals, and the functions thereof are also the same. Further, the image forming apparatus using the developing device of the present embodiment can also be controlled by the control unit shown in FIG.

  In the developing device of the present embodiment, a peeling member 12 made of a grid-like flat plate is arranged in the developer accommodating portion S downstream of the predoctor 7a in the sleeve rotation direction. The peeling member 12 is a member that is uniform in the longitudinal direction, and the gap Gh with respect to the developing sleeve 4 and the distance L2 with respect to the predoctor 7a are kept constant (see FIG. 22).

  In the developing device of FIG. 19, the toner replenished from the toner hopper 8 formed upstream of the predoctor 7a passes through the predoctor 7a and reaches the peeling member 12. Then, the developer that is going to move toward the doctor 6 by the conveying force of the developing sleeve 4 is once peeled from the developing sleeve 4 by the peeling member 12. The developer peeled off by the peeling member 12 is exchanged and mixed with the developer in the developer accommodating portion S, and is again carried on the developing sleeve 4 by magnetic force. By this replacement and mixing of the developer, the developer is stirred and uniformed, and toner charging is also promoted.

As described above, according to the present embodiment, by promoting the replacement and mixing of the developer on the developing sleeve 4 and the developer in the developer accommodating portion S, the developer due to a decrease in the charging ability of the carrier in the developer. Early deterioration can be prevented. In addition, even when toner replenishment unevenness occurs in the longitudinal direction of the developing sleeve 4, the uniformized developer can be conveyed to the developing region, so that development without uneven image density is possible.
Further, since the peeling member 12 formed of the grid-shaped flat plate is disposed close to the surface of the developing sleeve 4 so as to have a gap Gh, it is located at a position away from the developing sleeve surface in the developer accommodating portion S. A space where the developer can freely move is secured. Accordingly, the developer whose progress is blocked by the doctor 6 in the developer accommodating portion S moves to the toner replenishing port 8a side with almost no obstruction. Therefore, the toner density control function of the developer by changing the contact state between the developer moved to the toner replenishing port 8a and the toner in the toner hopper 8 and changing the state of toner intake into the developer. Can be reliably maintained.

(Example 3)
Next, more specific examples of the developing device according to this embodiment will be described.
Using the developing device shown in FIG. 19, first, 20 images were formed using as an image to be printed, a test chart constituted by alternating black and white with different toner consumption in the longitudinal direction of the developing sleeve 4. Thereafter, image formation was again performed using a test chart composed of uniform halftones on the entire surface. The development conditions were set in the same manner as in Table 1 using the peeling roller.

  Moreover, as the peeling member, flat plates 12a and 12b made of a grid-shaped nonmagnetic material as shown in FIGS. 20 and 21 were used. By using the peeling member 12 (12a, 12b), the developer on the developing sleeve 4 passes through the grid holes and is peeled from the developing sleeve 4. Further, the gap Gh between the peeling member 12 (12a, 12b) and the developing sleeve 4 was set to 0.3 mm, and the gap L2 between the peeling member 12 (12a, 12b) and the predoctor 7a was set to 10 mm (see FIG. 22).

As a result of the above-described image formation experiment performed under the above conditions, the developer is peeled off by the peeling member 12 and the developer is replaced and mixed, the developer is made uniform, and a good image without density unevenness can be obtained. did it.
Further, in the experiment in the developing device of this embodiment, it is preferable that the distance Gh between the peeling member 12 and the developing sleeve 4 and the distance Gd2 between the developing sleeve 4 and the predoctor 7a satisfy the relationship of the above expression (2). Mixing and stirring ability was obtained.
Further, since a part (only the upper layer) of the transport developer 3b on the developing sleeve 4 is peeled off using the peeling member 12 made of a grid-shaped flat plate, the transport developer 3b and the toner hopper 8 at the toner supply port 8a are peeled off. It was also possible to stably maintain a self-toner density control mechanism that changes the state of toner incorporation into the developer by changing the contact state with the toner.

[Embodiment 4]
FIG. 23 is a cross-sectional view showing a schematic configuration of a developing device according to the fourth embodiment of the present invention. In FIG. 23, the same parts as those in FIGS. 1 and 3 in the first embodiment are denoted by the same reference numerals, and the functions thereof are also the same. Further, the image forming apparatus using the developing device of the present embodiment can also be controlled by the control unit shown in FIG.

  The developing device of the present embodiment is provided with a stirring comb member 20 as a developer stirring member in the developer accommodating portion S downstream of the pre-doctor 10 and upstream of the doctor 6 in the developer transport direction by the developing sleeve 4. Yes. The stirring comb member 20 has a shape having a uniform width and thickness in the longitudinal direction, and the distance L2 from the predoctor 10 and the distance Gk between the tip of the stirring comb member 20 and the surface of the developing sleeve 4 are kept constant. The developer container S is fixed.

  In the developing device of the present embodiment, the agitation comb member 20 that faces the developing sleeve 4 in a non-contact manner at a position adjacent to the toner hopper 8 in the developer accommodating portion S enters the developer accommodating portion S. A part (upper layer part) of the conveyed developer on the developing sleeve 4 is stirred. By this agitation of the developer, mixing and agitation are performed between the conveyed developer on the developing sleeve 4 and the accommodated developer in the developer accommodating portion S. Further, by stirring the developer, the toner taken into the upper layer portion of the developer of the toner hopper 8 from the toner hopper 8 is stirred and mixed together with the developer to make the toner concentration in the developer uniform. As a result, the developer in which the toner density is uniformly stirred and mixed is carried on the developing sleeve 4 and conveyed toward the developing region, and is used for developing the electrostatic latent image on the photosensitive drum 1.

  According to the present embodiment, since a part of the developer (upper layer part) on the developing sleeve 4 is agitated by the agitation comb member 20, the conveying state of the developer on the developing sleeve 4 is not disturbed. Thus, a stable self toner density control function can be maintained. Further, the mixing and stirring of the developer by the stirring comb member 20 prevents the background contamination and the decrease in the developing density due to the deterioration of the developer, and there is no development density unevenness in the axial direction on the developing sleeve 4. Good development can be performed.

Example 4
Next, more specific examples of the developing device according to this embodiment will be described.
Using the developing device shown in FIG. 23, the experimental conditions were set within the ranges shown in Table 5.

  FIG. 24 is an explanatory view showing the arrangement position of the stirring comb member 20 in the present embodiment. In this figure, the gap Gk between the stirring comb member 20 and the developing sleeve 4 was set to 0.3 mm, and the distance L2 of the stirring comb member 20 from the predoctor 10 was set to 1 mm.

  FIG. 25 is a perspective view of the stirring comb member 20 used in this embodiment. The stirring comb member 20 has a continuous comb tooth portion 20 a on the side facing the developing sleeve 4. The tooth tip interval Pk of the comb tooth portion 20a was set to 2 mm.

  First, as shown in FIG. 11, the developing device having the above setting is configured alternately in black and white so that the toner consumption is different in the longitudinal direction (image width direction) orthogonal to the surface movement direction (G direction in the drawing) of the developing sleeve 4. The formed test chart 60 was used as an image to be printed, and 20 images were formed. Thereafter, image formation was again performed using a test chart composed of uniform halftones on the entire surface. As a result, the developer 3 was made uniform in the image width direction by the stirring comb member 20, and a good halftone image without density unevenness could be obtained.

(Comparative Example 2)
The structure of the developing device of this comparative example was the same as that of Example 4, and image formation was performed in the same procedure as described above without providing the stirring comb member 20. As a result, density unevenness in the image width direction has occurred in the halftone image.

  From the results of Example 4 and Comparative Example 2 described above, when developing a chart in which black and white images having different toner consumption amounts in the longitudinal direction of the developing sleeve 4 are developed, the development is performed without using the stirring comb member 20. If this is done, the toner density in the image width direction may become uneven and a good image may not be obtained. On the other hand, by providing the stirring comb member 20, toner density unevenness in the image width direction can be prevented. I found out that

  The mechanism that can prevent the toner density unevenness is considered as follows. That is, the toner 3a replenished from the upstream side of the predoctor 7a in the developer conveying direction passes through the gap between the developing sleeve and the predoctor 7a together with the conveying developer on the developing sleeve 4 and reaches the stirring comb member 20. The developer containing the toner 3 a is agitated by a resistance force generated between the developer 3 and the stirring comb member 20 when the developer 3 is conveyed on the developing sleeve 4, and the comb teeth 20 a of the stirring comb member 20 and the comb. When passing between the teeth 20a (hereinafter referred to as “between comb teeth”), the developer collides with the comb teeth 20a and is divided into both sides with the comb teeth 20a interposed therebetween. Lateral agitation is performed. Thus, the toner density is made uniform in the axial direction of the developing sleeve 4 and charging of the toner 3a is promoted. As a result, even when toner replenishment unevenness occurs in the longitudinal direction of the developing sleeve 4, the toner density in that direction is made uniform and a good image can be obtained.

  Further, the stirring comb member 20 is provided with a gap Gk with respect to the developing sleeve 4 and agitates a part (upper layer portion) of the transported developer on the developing sleeve 4. The movement of the conveyed developer on the developing sleeve 4 is not hindered. Therefore, there is no fear of damaging the self-toner density control mechanism unique to this type of developing device. In particular, in Example 4, since the developer stirring member is formed in a comb-teeth shape, the movement of the developer in the developer accommodating portion S blocked by the doctor 6 is hardly hindered. The toner 3a taken in on the replenished developer can be stirred while reliably maintaining the control mechanism.

According to the experiments by the present inventors, in Example 4, a good stirring is obtained when a nonmagnetic material is used for the stirring comb member 20 and the interval Gk is set so as to satisfy the following expression (4). It turns out that ability is acquired.

  By setting the gap Gk in this way, at least a part of the toner 3a replenished from the restriction position by the predoctor 7a is surely connected to the comb teeth portion 20a of the stirring comb member 20 and the comb teeth on the downstream side in the developer conveying direction. Since it passes between the parts 20a, the replenishment toner 3a can be reliably laterally stirred.

  Furthermore, from various experimental results, it has been found that a good developer stirring ability can be obtained by setting the tooth tip interval Pk to 0 <Pk ≦ 5 mm. Also in the fourth embodiment, the tooth tip interval Pk is set to 5 mm or less. As a result, toner density unevenness in the image width direction can be satisfactorily prevented.

[Embodiment 5]
FIG. 26 is a cross-sectional view showing a schematic configuration of a developing device according to the fifth embodiment of the present invention. This developing device has substantially the same configuration as the developing device shown in FIG. 23 shown in the fourth embodiment. The main differences from the developing device of FIG. 23 are as follows.
In the developing device of this embodiment, instead of the developer agitating member, it faces the surface of the developing sleeve 4 at a position adjacent to the toner hopper 8 in the developer accommodating portion S and is carried and conveyed by the developing sleeve 4. A sheet member 21 is provided as a flexible plate-like member that comes into contact with a portion of the developer that has taken in toner from the toner hopper 8.
Further, in the developing device of FIG. 23, the bottom surface of the toner replenishing port 8a is slightly curved in a tray shape, whereas the bottom surface of the toner replenishing port 8a of the developing device of the present embodiment is formed from the toner hopper 8 to the developing sleeve 4. It has a shape that is linearly inclined downward. Further, in the cross section obtained by cutting the toner hopper 8 along a horizontal plane, the area inside the toner hopper 8 is narrower than that of the developing device of FIG. Further, in the developing device of FIG. 23, the developer storage case 7 is configured such that the boundary between the upper wall surface, the side wall surface, and the lower wall surface (predoctor 7a) surrounding the developer storage portion S is a curved surface. On the other hand, in the developing device of FIG. 26, the developer containing case 7 is configured such that the boundary between the side wall surface surrounding the developer containing portion S and the lower wall surface (predoctor 7a) is not curved but is bent sharply. It is configured.
Since the apparatus configuration and operations other than those described above are substantially the same as those in FIG.

Next, more specific Examples 5 to 9 of the developing device according to the present embodiment will be described.
(Example 5)
FIG. 27 is an explanatory diagram of a main part of the developing device according to the present embodiment. This figure is a partially enlarged view of the developer accommodating portion S and the toner intake portion into the developer accommodating portion S in the developing device of FIG. In this developing device, a sheet member 21 as a flexible plate member is provided on the side surface of the predoctor 7a on the developer accommodating portion S side. The seat member 21 is made of a polyurethane seal. However, the material used for the sheet member 21 is not limited to the polyurethane seal, and may be a flexible sheet-like or plate-like member, and the same applies to the following embodiments.
The sheet member 21 is affixed to the inner surface of the predoctor 7a on the developer accommodating portion S side, and the end portion on the developing sleeve 4 side becomes a free end 21a and is carried on the surface of the developing sleeve 4 and conveyed. So that it is bent toward the downstream side in the developer conveyance direction. This position becomes the third restriction position, and the sheet member 21 is bent or restored by its flexibility due to the pressure of the toner 3a taken into the developer accommodating portion S at the second restriction position by the predoctor 7a. The sheet member 21 prevents the toner 3a excessively taken into the developer from being conveyed to the downstream region in the developer conveying direction by the developing sleeve 4. At the same time, the toner density in the developer is made uniform in the image width direction perpendicular to the developer transport direction by the developing sleeve 4, that is, in the image width direction, at the third restriction position. The excessive toner 3a is removed in this way, and the toner 3a, which is uniform in the image width direction, is taken into the transport developer on the developing sleeve 4 and is further uniformly developed at the restriction position by the doctor 6. Used for.
As a result of developing the sheet member 12 as described above, the formed image had no density unevenness in the width direction, and a good image was obtained.

(Example 6)
FIG. 28 is an explanatory diagram of a main part of the developing device according to the sixth embodiment. This figure is also a partially enlarged view of the developer accommodating portion S and the toner intake portion into the developer accommodating portion S in the developing device of FIG. The difference of the sheet member 22 of the sixth embodiment from the fifth embodiment is that the free end 22 a of the sheet member 22 is longer than the shortest length for contacting the surface of the developing sleeve 4. As a result, the tip of the free end 22a comes into contact with the surface of the developing sleeve 4 and is bent along with the movement of the surface of the developing sleeve 4 in the moving direction. This position is the third restricting position, and the toner 3 a carried and conveyed by the developing sleeve 4 moves relative to the sheet member 22 while contacting the sheet member 22. As a result, excess toner 3a is blocked at the third restriction position, and the toner concentration in the developer is made uniform in the image width direction perpendicular to the developer transport direction by the developing sleeve 4.
As described above, the excessive toner 3a is removed and the toner 3a, which is uniform in the image width direction, is taken into the transported developer on the developing sleeve 4, passes through the restriction position by the doctor 6, and is used for development. The
As a result of developing the sheet member 22 as described above, the formed image had no density unevenness in the width direction, and a good image was obtained.

(Example 7)
FIG. 29 is an explanatory diagram of a main part of the developing device according to the seventh embodiment. This figure is also a partially enlarged view of the developer accommodating portion S and the toner 3b taking-in portion into the developer accommodating portion S in the developing device of FIG. The sheet member 23 of the seventh embodiment is longer than the shortest length for the free end 23a of the sheet member 23 to contact the surface of the developing sleeve 4 as in the sixth embodiment. Further, by adjusting the thickness of the sheet member 23 of the seventh embodiment, the free end 23a is curved by the pressure generated by the transport developer on the surface of the developing sleeve 4. As a result, the free end 23a of the sheet member 23 comes into surface contact with the transport developer on the developing sleeve 4 uniformly in the image width direction and long in the developer transport direction. This surface contact portion is the third restriction position.
With the above configuration, the excessive toner 3a is removed, and the toner 3a that is uniform in the image width direction is taken into the transport developer on the developing sleeve 4 and passes through the restriction position by the doctor 6 and used for development. .
As a result of developing the sheet member 23 as described above, the formed image had no density unevenness in the width direction, and a good image was obtained.

(Example 8)
FIG. 30 is an explanatory diagram of the main part of the developing device according to the eighth embodiment. This figure is also a partially enlarged view of the developer accommodating portion S and the toner intake portion into the developer accommodating portion S in the developing device of FIG. The sheet member 24 used in the developing device has a length (free length) of the free end 24a of the sheet member 24 that is longer than the shortest length for contacting the surface of the developing sleeve 4, and the free end 24a By adjusting the length, the free end 24a is curved by the pressure generated by the conveyed developer on the surface of the developing sleeve 4. As a result, the free end 24a of the sheet member 24 comes into surface contact with the transport developer on the developing sleeve 4 uniformly in the transport direction width direction and long in the developer transport direction. This surface contact portion is the third restriction position.
With the above configuration, the excessive toner 3a is removed, and the toner 3a that is uniform in the image width direction is taken into the transport developer on the developing sleeve 4 and passes through the restriction position by the doctor 6 and used for development. .
As a result of developing the sheet member 24 as described above, the formed image had no density unevenness in the width direction, and a good image was obtained.

  In the developing device of FIG. 30, the end of the sheet member 24 opposite to the region where the free end 24a is formed is necessary for fixing the side surface of the predoctor 7a on the developer accommodating portion S side. It is longer than the length. Specifically, it has a length extending from an inner side surface portion of the predoctor 7a in a direction perpendicular to the surface of the developing sleeve 4 and a portion which is refracted from the portion and becomes a side surface of the developer accommodating portion S. The sheet member 24 is attached to the inner side surface of the pre-doctor 7a so as to be bent so as to float the refracted position of the inner side surface of the pre-doctor 7a. As a result, the circulation of the developer 3 in the developer accommodating portion S can be made smoother. Therefore, even if the shape of the inner surface of the developer accommodating portion S is discontinuous at the refracting portion, there is an effect that the shape of the inner surface can be corrected to a desired shape by the sheet member 24.

Example 9
FIG. 31 is an explanatory diagram of a main part of the developing device according to the ninth embodiment. This figure is also a partially enlarged view of the developer accommodating portion S and the toner intake portion into the developer accommodating portion S in the developing device of FIG. In the sheet member 25 used in the developing device, the length of the free end 25a of the sheet member 25 is sufficiently longer than the shortest length for contacting the surface of the developing sleeve 4, and the portion facing the surface of the developing sleeve 4 is positioned upward. The loop is wound up so that the outer circumferential surface portion 25b of the curved surface of the loop comes into contact with the transport developer on the surface of the developing sleeve 4. As a result, the sheet member 25 whose strength has been increased by the tension of the outer peripheral surface portion 25b comes into contact with the conveyed developer on the developing sleeve 4 to form a third restriction position.
With the above configuration, the toner 3a, which removes excess toner 3a and becomes uniform in the image width direction, is taken into the transport developer on the developing sleeve 4, and is made even more uniform at the restriction position by the doctor 6 for development. used.
As a result of developing the sheet member 25 as described above, the formed image was free from density unevenness in the width direction, and a good image was obtained.

  According to the developing devices of Examples 5 to 9 described above, the sheet members 21 to 25 serve to regulate the incorporation of the toner 3a into the developer and make the toner density uniform in the image width direction. Unevenness can be prevented.

  Furthermore, the stirring comb member (developer stirring member) 20 in the fourth embodiment and the sheet members (flexible plate-like members) 21 to 25 in the fifth embodiment are merely fixed in the developer accommodating portion S. Since the toner density can be made uniform in the longitudinal direction of the developing sleeve 4, it is not necessary to drive a predetermined member with a motor or the like in order to forcibly stir the developer in the developer accommodating portion S. An effect of preventing uneven development density in the image width direction can be obtained.

  In each of the above embodiments, the case of the developing device provided with the predoctor as the second developer regulating member disposed so as to face the developing sleeve surface with a predetermined gap has been described. This can also be applied to the case where no is provided, and the same effect can be obtained.

FIG. 2 is an enlarged cross-sectional view of a main part of the developing device used in the printer according to the first embodiment of the present invention. FIG. 2 is a front view illustrating a schematic configuration of the printer. Sectional drawing which shows schematic structure of the whole developing device. Explanatory drawing which shows the positional relationship of a developing sleeve, a peeling roller, a predoctor, etc. in the developing device. The side view of the peeling roller used with the developing device. (A) And (b) is explanatory drawing of the self-toner control mechanism in the developing device. FIG. 3 is a block diagram of a main part of a control unit in the printer of the present embodiment. FIG. 6 is a characteristic diagram showing a relationship between temperature and the degree of aggregation of toner. The characteristic view which shows the relationship between humidity and the aggregation degree of a toner. Sectional drawing of the principal part of the developing device which concerns on a modification. Explanatory drawing of the test chart image used for the experiment by the image development apparatus of an Example. FIG. 5 is a front view illustrating a schematic configuration of a printer according to a second embodiment of the invention. Sectional drawing which shows schematic structure of the whole developing device. Sectional drawing which shows schematic structure of the developing device. Sectional drawing which shows schematic structure of the developing device which concerns on a modification. The perspective view of the peeling roller used for the developing device. (A) is a perspective view of the peeling roller which concerns on a modification. (B) And (c) is explanatory drawing of the magnetic pole arrangement | positioning in the surrounding surface of the peeling roller which concerns on another modification. (A)-(e) is explanatory drawing which shows the rank of a density nonuniformity level. Sectional drawing which shows schematic structure of the developing device which concerns on the 3rd Embodiment of this invention. The perspective view of the peeling member used for the image development apparatus concerning the Example of the embodiment. The perspective view of the other peeling member used for the developing device. Explanatory drawing of the space | interval of each part in the developing device. Sectional drawing which shows schematic structure of the developing device which concerns on the 4th Embodiment of this invention. Explanatory drawing which showed the arrangement position of the comb member for stirring in the developing device. The perspective view of the comb member for stirring. Sectional drawing which shows schematic structure of the developing device which concerns on the 5th Embodiment of this invention. FIG. 10 is an explanatory diagram of a main part of a developing device according to Embodiment 5. FIG. 10 is an explanatory diagram of a main part of a developing device according to Embodiment 6. FIG. 10 is an explanatory diagram of a main part of a developing device according to Embodiment 7. FIG. 10 is an explanatory diagram of a main part of a developing device according to an eighth embodiment. FIG. 10 is an explanatory diagram of a main part of a developing device according to Embodiment 9.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Developing apparatus 2a Casing 3 Developer 3a Toner 3b Conveying developer 3c Accommodating developer 3d Release developer 3e Retention developer 4 Developing sleeve 5 Magnet roller 6 Doctor 7 Developer accommodating case 7a Predoctor 8 Toner hopper 8a Toner replenishment Port 9 Toner agitator 10 Wedge-shaped peeling member 11 Peeling roller (magnetic material)
12 Peeling member (grid-like flat plate)
13, 14 Peeling roller (magnet roller)
20 Stirring comb member 21 to 25 Sheet member 50 Charging roller 51 Optical writing unit 52 Paper 53 Transfer roller 100 Engine control unit 101 Engine control CPU
110 Image data processing unit S Developer storage unit

Claims (22)

A developer carrying member having a magnetic field generating means therein and moving on the surface so as to carry and carry a developer containing toner and a magnetic carrier;
A first developer regulating member that regulates the amount of the developer carried on the developer carrying member and conveyed toward the development area;
A developer containing portion for containing a developer whose conveyance to the developing region is regulated by the first developer regulating member;
A toner container having a toner supply opening facing the surface of the developer carrier on the upstream side of the developer container in the developer conveying direction;
The surface of the developer carrying member is carried and conveyed so as to follow the surface of the developer carrying member from the facing portion facing the toner supply opening of the toner containing portion toward the developer containing portion. A second developer regulating member that regulates the amount of conveyed developer on the developer carrying member,
The gap between the second developer regulating member and the surface of the developer carrying member is such that the transported developer by the second developer regulating member is increased as the toner concentration of the carried developer on the developer carrying member increases. In the developing device set to increase the amount of regulation of
In the developer accommodating portion between the second developer regulating member and the first developer regulating member, it faces the surface of the developer carrying member in a non-contact manner and follows the surface of the developer carrying member. A peeling member that peels off the upper layer portion of the transported developer carried on
The conveying developer reaching該剥away member is carried and conveyed by the developer carrier, and a non-stripping developer conveyed to pass between developer carrying member and該剥release member, the release A non-peeling developer that is separated by a member and separated into a peeled developer mixed with the developer contained in the developer containing portion while moving along the surface of the peelable member opposite to the developer carrying member. The developing device, wherein the release developer merges downstream of the release member in the developer transport direction with respect to the release member . The developing device according to claim 1.
When the gap between the peeling member and the surface of the developer carrier is Gh, and the gap between the second developer regulating member and the surface of the developer carrier is Gd2,
0 <Gh <Gd2
A developing device satisfying the relationship: The developing device according to claim 1.
The developing device, wherein the magnetic field generating means does not have a magnetic pole between a position facing the peeling member and a position facing the second developer regulating member. The developing device according to claim 3.
The magnetic flux density on the surface of the developer carrier from the position facing the second developer regulating member to the position facing the peeling member is a magnetic flux that can carry the developer on the surface of the developer carrier. A developing device having a density. The developing device according to claim 1, 2, 3, or 4.
The peeling member is a roller-shaped rotating member,
A developing device, comprising: a rotation driving unit that rotationally drives the peeling member so that the surface moves in a direction opposite to the surface of the developer carrier at a portion facing the developer carrier. The developing device according to claim 5.
A developing device, wherein the peeling member is made of a magnetic material. The developing device according to claim 6.
The release member is supported at both ends in a direction intersecting the developer transport direction on the developer carrier,
A developing device, wherein a diameter of a central portion of the peeling member in the intersecting direction is smaller than a diameter of both end portions. The developing device according to claim 1, 2, 3, or 4.
The peeling member is a member that extends along a direction intersecting a developer transport direction on the developer carrying member and includes a magnetic body;
A developing device, comprising: a rotation driving unit that rotationally drives the peeling member so that the surface moves in a direction opposite to the surface of the developer carrier at a portion facing the developer carrier. The developing device according to claim 1, 2, 3, or 4.
The peeling member is a member extending along a direction intersecting the developer transport direction on the developer carrying member and having a magnetic pole magnetized on the surface,
A developing device, comprising: a rotation driving unit that rotationally drives the peeling member so that the surface moves in a direction opposite to the surface of the developer carrier at a portion facing the developer carrier. The developing device according to claim 9.
The peeling member is a roller-shaped rotating member,
A developing device characterized in that a plurality of the magnetic poles are magnetized on the surface of the peeling member. The developing device according to claim 10.
The developing device according to claim 1, wherein the plurality of magnetic poles are formed by alternately magnetizing S poles and N poles. The developing device according to claim 11.
The developing device, wherein each of the plurality of magnetic poles is linearly magnetized along an extending direction of a rotation shaft of the peeling member. The developing device according to claim 10.
The plurality of magnetic poles are magnetized so that a plurality of magnetic pole groups in which S poles and N poles are alternately arranged in the extending direction of the rotating shaft of the peeling member are arranged in the circumferential direction of the peeling member surface. A developing device. The developing device according to claim 5, 6, 7, 8, 9, 10, 11, 12 or 13.
The developing device according to claim 1, wherein the rotation driving means is capable of being driven to rotate by changing a rotation speed of the peeling member. The developing device according to claim 14, wherein
A developing device comprising a control means for controlling the rotation driving means based on an image ratio in an image to be developed. The developing device according to claim 14, wherein
Temperature measuring means for measuring the temperature in the apparatus;
A developing device comprising: a control means for controlling the rotation driving means based on a temperature measurement result of the temperature measuring means. The developing device according to claim 14, wherein
Humidity measuring means for measuring the humidity in the device;
A developing device comprising: a control unit that controls the rotation driving unit based on a humidity measurement result of the humidity measuring unit. The developing device according to claim 5, 6, 7, 8, 9, 10, 11, 12 or 13.
A developing device characterized in that the surface of the release member is roughened. The developing device according to claim 6 or 7,
The developing device, wherein the peeling member is made of a magnetic material and faces a peak position of a normal direction magnetic flux density distribution on the surface of the developer carrying member. The developing device according to claim 19,
A developing device, wherein a normal direction magnetic flux density on a surface opposite to a side facing the developer carrying member on a peripheral surface of the peeling member is 5 mT or more. The developing device according to claim 1, 2, 3, or 4.
The developing device, wherein the peeling member is a grid-like flat plate. A latent image forming means for forming a latent image on the latent image carrier, a developing device for developing the latent image on the latent image carrier to form a toner image, and a toner image on the latent image carrier. In an image forming apparatus provided with a transfer device for transferring to
An image forming apparatus comprising the developing device according to claim 1 as the developing device.

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