JP2009109863A - Image developing unit, process unit, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing unit which forms a cloud of toner to develop images, and can reliably prevent the toner from scattering, and also to provide a process unit and an image forming device incorporating this developing unit. <P>SOLUTION: The developing unit 6 has a toner carrying roller 7 which carries the toner in a cloud state by applying a voltage to the electrodes to cause the toner hopping, and a casing 61 forming a toner container 66. The entrance width Wa which is the distance from the casing entrance side edge 61a forming the entrance section 8 to the toner carrying roller 7 surface, and the cloud height H which is the height of the toner cloud on the surface of the toner carrying roller 7 are set up to satisfy the relation, the entrance width Wa≥the cloud height H. Further, it has a sheet 65 as the toner backflow prevention means arranged with its surface facing the surface of the toner carrying roller 7 in a manner making the distance to the toner carrying roller 7 smaller and smaller toward the downstream. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing device for developing a latent image on a latent image carrier with toner hopped on an endlessly moving surface of a toner carrier, and a process unit and an image forming apparatus using the same.

  Conventionally, as a developing device mounted on an image forming apparatus such as a copying machine, a facsimile machine, a printer, etc., toner that has been hopped on the surface of a toner carrier is not used for development but toner that is adsorbed on a developing roller or a magnetic carrier. Is used for development.

For example, the developing device described in Patent Document 1 includes a cylindrical toner carrier including a plurality of electrodes arranged at a predetermined pitch in the circumferential direction. These electrodes are formed by repeatedly arranging electrode pairs composed of two adjacent electrodes. An alternating electric field is formed between the two electrodes in each electrode pair. Then, the toner located on one electrode in the electrode pair floats and landes on the other electrode, or floats on the other electrode and landes on one electrode. Then, by repeating the hopping in this manner, the toner becomes a cloud state on the toner carrier, and the position of the toner carrier and the latent image carrier facing each other due to the surface movement accompanying the rotational driving of the cylindrical toner carrier. To the developing position.
The toner supplied to the toner carrier is accommodated in a developing casing, and the toner carrier is opposed to the latent image carrier at an opening formed in a part of the developing casing. The toner that has passed through the developing position without adhering to the latent image carrier is transported by the toner carrier in the cloud state, and returns to the developing casing that contains the toner to be supplied to the toner carrier.

  At the development position of such a developing device, the toner that has entered a cloud state and has floated to the vicinity of the latent image on the latent image carrier does not descend toward the electrode of the toner carrier, and is attracted to the electric field by the latent image. It sticks to the latent image. In such a configuration, not the toner adsorbed on the developing roller or the magnetic carrier, but toner that is in a cloud state and does not exhibit the adsorbing force from the toner carrier is used for development. As a result, it is possible to realize low-potential development that cannot be realized by the conventional one-component development method or two-component development method. For example, toner can be selectively attached to an electrostatic latent image having a potential difference of 100 [V] or less with respect to surrounding non-image portions.

JP-A-3-21967 JP 2002-341656 A

  However, the toner carrier is susceptible to the influence of the air flow as much as the adsorption force of the toner carrier may not be exhibited. For this reason, if an air flow from the inside of the developing casing toward the opening occurs in the space between the toner carrying body through which the toner that has passed through the developing position returns to the inside of the developing casing and the inner wall of the developing casing, The toner that has passed through the position may flow backward, causing toner scattering from the opening.

It is considered that the air flow from the developing casing toward the opening is generated due to the following causes. That is, since the surface of the toner carrier moves toward the inside of the developing casing at the inlet portion, which is the downstream end of the toner carrier in the toner conveyance direction, the air near the surface of the toner carrier is It moves in the developing casing together with the surface of the body. As a result, air flows from the opening into the developing casing at least near the surface of the toner carrier. On the other hand, a toner regulating member that regulates the amount of toner toward the developing position is disposed on the surface of the toner carrying member that conveys the toner toward the outlet portion that is the upstream end of the toner carrying member in the toner conveyance direction. Has been. The toner regulating member is in contact with the surface of the toner carrier and is in contact with a contact pressure that allows the accompanying toner to pass therethrough, and no air flows from the inside of the developing casing toward the outlet portion. For this reason, when the toner carrier is driven to rotate, the pressure in the developing casing rises due to the flow of air from the opening toward the developing casing. If the pressure in the developing casing continues to rise, there will be no air escape. As a result, in the space between the toner carrier on the inlet side and the inner wall of the developing casing, an opening is formed from the inside of the developing casing in an area that is separated from the surface of the toner carrier to some extent and is not easily affected by the surface movement of the toner carrier. The air flow toward
The toner in the cloud state is also present in a region away from the surface of the toner carrier to some extent, and since it is difficult to exert the adsorption force of the toner carrier, it is easily affected by the air flow. The toner scatters by moving toward the opening along with the air flow.

In order to solve such a problem, the present inventors provide a seal member close to the toner carrier and narrow the gap at the inlet, so that the toner flows backward and passes through the inlet and scatters from the opening. I was restrained from doing it. This is due to the following reason. That is, by narrowing the gap at the inlet portion, the amount of air that moves from the inlet portion toward the inside of the developing casing along with the movement of the surface of the toner carrier is suppressed, and the increase in pressure in the developing casing is suppressed, thereby reducing the development. It can suppress that the flow of the air which goes to an opening part from the inside of a casing arises. Furthermore, since the air flow in the region at a certain distance from the toner carrier at the entrance can be inhibited, it is possible to suppress the flow of air from the developing casing toward the opening. By suppressing the generation of air flow toward the opening, it is possible to suppress the back flow of the toner and to prevent the toner from passing through the inlet and scattering from the opening.
However, when the gap at the inlet is narrowed, the toner carried on the toner carrier in the cloud state collides with the end of the developing casing serving as the inlet and the portion of the seal member that does not face the toner carrier, and the toner carrier In some cases, the toner bounces away from the surface and causes toner scattering.
Note that such a problem is not limited to the toner restriction member that obstructs the air flow from the outlet side, but on the outlet side compared to the air flow toward the inside of the developing casing on the inlet side. A similar problem may occur if the apparatus is less likely to generate an air flow toward the outside of the developing casing.
Further, as a developing device for developing with toner hopped on the surface of the toner carrying member, a device described in Patent Document 2 is known in addition to the one described in Patent Document 1. This developing device has a toner transport substrate as a toner carrier having a plurality of electrodes arranged at a predetermined pitch on an insulating support. These electrodes are formed by repeatedly arranging electrode sets composed of three or more electrodes arranged continuously. A pulse voltage that is out of phase with each other is applied to each electrode in an electrode set including three or more electrodes. As a result, a traveling electric field is formed on the transport substrate, in which the toner is sequentially moved from one end side to the other end side while hopping the toner. The toner on the surface of the transport substrate is repeatedly hopped from above one electrode toward the adjacent electrode in a direction from one end side to the other end side of the substrate. And a latent image carrier such as a photosensitive member are conveyed to a developing region facing each other with a predetermined gap. Even in such a configuration, the same problem may occur if the surface of the toner carrier is moved endlessly without relying only on the toner hopping movement.

  The present invention has been made in view of the above problems, and an object of the present invention is to use a developing device with toner in a cloud state, which can more reliably prevent the occurrence of toner scattering, The present invention also provides a process unit and an image forming apparatus provided with the developing device.

In order to achieve the above object, a first aspect of the present invention is a toner carrier comprising a plurality of electrodes arranged in a predetermined direction, a toner supply means for supplying toner to an endlessly moving surface of the toner carrier, Forming a toner containing portion for containing toner to be supplied to the toner carrying member; and a developing casing having the toner carrying member and the toner supplying means inside, wherein the toner carrying member is formed in a part of the developing casing. The toner held on the surface of the toner carrying body facing the latent image carrying body at the formed opening is hopped on the surface by an electric field formed by applying a voltage to the plurality of electrodes. In this state, the toner carrying member and the latent image carrier are conveyed to a developing position that is opposite to the toner carrying member, and toner is attached to the latent image carried on the latent image carrier at the developing position. Develop the image, In a developing device for transporting toner that has passed through the developing position without adhering to an image carrier into a developing casing in a cloud state, an inlet portion that is an end of the opening on the downstream side of the toner carrier in the toner transport direction The inlet width Wa, which is the distance from the end of the developing casing to the surface of the toner carrier, and the cloud height H, which is the height of the toner in the cloud state on the surface, satisfy Wa ≧ H. Satisfying the relationship, and having toner backflow prevention means for preventing toner from moving from the inside of the developing casing toward the inlet portion on the downstream side of the toner carrying direction of the toner carrier from the inlet portion. It is a feature.
According to a second aspect of the present invention, in the developing device of the first aspect, as the toner backflow preventing means, the surface thereof faces the surface of the toner carrier, and the distance between the toner carrier and the surface is the toner. A carrier-facing member arranged to be closer to the downstream side of the carrier in the toner conveyance direction is provided.
According to a third aspect of the present invention, in the developing device according to the first or second aspect, the inner wall surface of the developing casing and the surface of the toner carrier are sealed as the toner backflow preventing means in contact with the toner carrier. An inlet internal seal member is provided, and the contact pressure of the seal member with respect to the toner carrier is such that the toner particles in contact with the surface of the toner carrier are in contact with the endlessly moving surface of the toner carrier. The contact pressure is such that it can pass through and can prevent the backflow of toner.
According to a fourth aspect of the present invention, in the developing device of the third aspect, the toner carrying member upstream of the toner carrying member in the toner carrying member upstream of the outlet portion of the opening on the upstream side of the toner carrying member in the toner carrying direction. A toner regulating member that regulates a toner layer on the toner carrier, the inlet inner seal member abuts on the surface of the toner carrier with an inlet inner seal abutting pressure Fa, and the toner regulating member It is abutted against the surface of the toner carrying member with a regulating member abutting pressure Fb, and the inlet inner seal abutting pressure Fa and the regulating member abutting pressure Fb satisfy the relationship Fa ≦ Fb. is there.
The invention according to claim 5 is the developing device according to claim 2, wherein the toner carrier is located downstream of the inlet portion in the toner transport direction with respect to the inlet portion and at a position where the carrier-facing member is disposed. An inlet space portion having a width in the normal direction of the surface of the toner carrying member wider than the inlet width Wa is formed on the upstream side in the toner conveying direction.
According to a sixth aspect of the present invention, in the developing device of the third or fourth aspect, the toner is more downstream than the inlet portion in the toner conveying direction of the toner carrier, and more than the position where the inlet inner seal member is disposed. An inlet space portion in which the width of the surface of the toner carrier in the normal direction is wider than the inlet width Wa is formed upstream of the carrier in the toner conveyance direction.
Further, the invention according to claim 7 is the developing device according to claim 1, wherein the toner carrier is disposed downstream of the inlet portion in the toner transport direction as the toner backflow prevention means. The surface of the surface in the normal direction is wider than the entrance width Wa, forming an entrance space.
According to an eighth aspect of the present invention, in the developing device according to the fifth, sixth, or seventh aspect, the inlet space includes an electrode member to which a bias having a polarity opposite to the charging potential of the toner is applied. is there.
According to a ninth aspect of the present invention, in the developing device of the first, second, third, or fourth aspect, an electrode member to which a bias having a polarity opposite to a toner charging potential is applied is provided as the toner backflow prevention means. It is provided on the downstream side of the toner carrier in the toner transport direction from the portion.
According to a tenth aspect of the present invention, in the developing device of the first, second, third, fourth, fifth, sixth, seventh, eighth, or ninth aspect, the toner carrying member is provided more as the toner backflow prevention means than the inlet portion. It has a communication port that communicates the space on the downstream side in the toner conveying direction with the outside of the developing casing, and a filter member that prevents toner from passing through the communication port.
Further, the invention of claim 11 is the developing device of claim 5, 6, 7 or 8, wherein, as the toner backflow prevention means, a communication port for communicating the inlet space and the outside of the developing casing, and the communication It has a filter member for preventing toner from passing through the mouth.
According to a twelfth aspect of the present invention, in the developing device according to the first, second, third, fourth, fifth, sixth, seventh, eighth, tenth, or eleventh aspects, the opening is upstream of the toner carrying member in the toner carrying direction. The outlet width Wb, which is the distance from the end of the developing casing forming the end to the surface of the toner carrier, and the inlet width Wa satisfy the relationship Wa ≧ Wb.
The invention according to claim 13 is the developing device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, wherein the toner carrier of the toner carrier in the opening is conveyed. A toner regulating member that regulates the toner layer on the toner carrier on the upstream side in the toner transport direction of the toner carrier from the outlet that is the upstream end of the toner carrier, and the toner carrier from the outlet The width in the normal direction of the surface of the toner carrying member on the upstream side in the toner carrying direction and on the downstream side in the toner carrying direction of the toner carrying member from the position including the toner regulating member is The outlet space is wider than the outlet width Wb, which is the distance from the end of the developing casing to the surface of the toner carrier.
The invention according to claim 14 is the developing device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13, wherein the toner carrier at the opening is provided. One end is fixed to the end portion of the developing casing of the inlet portion, which is the downstream end portion of the toner conveying direction, and the outlet portion, which is the upstream end portion of the toner carrier, in the toner conveying direction. Is provided with an inlet seal and an outlet seal that are free ends and close to the surface of the latent image carrier, and the inlet seal and the outlet seal are conductors.
According to a fifteenth aspect of the present invention, in the developing device of the fourteenth aspect, a bias having the same polarity as the charging potential of the toner is applied to the inlet seal and the outlet seal.
According to a sixteenth aspect of the present invention, there is provided a latent image carrier that carries a latent image, a charging unit that uniformly charges the surface of the latent image carrier, and a cleaning unit that cleans the surface of the latent image carrier. In a process unit in which at least one of them and a developing unit that develops a latent image carried on the latent image carrier are held by a common holder so that the unit can be attached to and detached from the image forming apparatus main body. As a developing means, the developing device of claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 is used.
According to a seventeenth aspect of the present invention, there is provided an image forming apparatus having a latent image carrier that carries a latent image and a developing unit that develops the latent image on the latent image carrier. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 developing device is used.

  In the inventions of claims 1 to 17, by setting the inlet width, which is the gap between the inlet portions of the developing casing, wider than the cloud height, the hopped toner collides with a portion of the inlet portion that does not face the toner carrier. Can be prevented. For this reason, it is possible to prevent the toner from rebounding in a direction other than the surface of the toner carrier. Further, even if the inlet width is set wider than the cloud height by the toner backflow prevention means provided on the downstream side of the toner carrying direction of the toner carrier from the inlet portion, it is possible to prevent the toner from traveling from the inside of the developing casing to the inlet portion. it can.

  According to the first to seventeenth aspects of the present invention, it is possible to prevent toner scattering due to toner splashing in a direction other than the surface of the toner carrying member, and to prevent toner scattering due to toner backflow at the inlet portion. There is an excellent effect that scattering can be prevented.

Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment of an electrophotographic printer (hereinafter referred to as a printer 100) will be described.
FIG. 1 is a schematic configuration diagram illustrating a printer 100 according to the present embodiment. The printer 100 can form a full-color image by superimposing black, magenta, cyan, and yellow (hereinafter referred to as K, M, C, and Y) toner images. The belt unit 1, the four process units 60 (K, M, C, Y), the four optical writing units 4 (K, M, C, Y), the registration roller pair 53, the secondary transfer roller 12, the fixing The apparatus 3 includes a paper feed cassette 50, a paper feed path 52, and the like.

  The belt unit 1 includes a photoconductor belt 11 in which an organic photoconductor serving as a latent image carrier is configured in an endless belt shape, and the photoconductor belt 11 is stretched in a vertically long posture that takes a space in a vertical direction rather than a horizontal direction. Move endlessly counterclockwise in the figure. More specifically, the photosensitive belt 11 is stretched while being supported from the back side by a driving roller 11b, a tension roller 11c, a secondary transfer backup roller 11a, and four development counter rollers 10 (K, M, C, Y). ing. Then, the photosensitive belt 11 is moved endlessly by the rotation of a driving roller 11b that is driven to rotate counterclockwise in the drawing by a driving means (not shown). The left extending surface (hereinafter referred to as the left extending surface) in the drawing of the photosensitive belt 11 is in a posture extending substantially in the vertical direction.

  Process units 60 (K, M, C, Y) for K, M, C, Y are arranged in the vertical direction on the left side of the left-hand stretched surface of the photoreceptor belt 11 in the drawing. , Respectively, facing the left-hand stretched surface of the photoreceptor belt 11. These four process units 60 (K, M, C, Y) respectively include a developing device 6 (K, M, C, Y) and a charging device 2 (K, M, Y) for uniformly charging the photosensitive belt 11. C, Y) are held by a common holding body (not shown) as one unit. As shown in FIG. 2, the developing device 6 and the charging device 2 are integrally attached to and detached from the housing of the printer 100 as a process unit 60 and can be replaced by the user.

  In FIG. 1 described above, among the four developing devices 6 (K, M, C, Y), the K charging device 2K is located above the K developing device 6K located at the uppermost position in the vertical direction. Is disposed so as to face the left-side stretched surface of the photosensitive belt 11. Further, in the vertical direction, the charging device 2M for M is disposed between the developing device 6K for K and the developing device 6M for M so as to face the left-side stretched surface of the photosensitive belt 11. ing. Further, between the developing device 6M for M and the developing device 6C for C, the charging device 2C for C is disposed so as to face the left-side stretched surface of the photosensitive belt 11. Further, a Y charging device 2Y is disposed between the C developing device 6C and the Y developing device 6Y so as to face the left-side stretched surface of the photosensitive belt 11.

  On the left side of the four developing devices 6 (K, M, C, Y) arranged in the vertical direction, four optical writing units 4 (K, M, C, Y) are arranged in the vertical direction. It is installed. These optical writing units 4 (K, M, C, Y) drive four semiconductor lasers (not shown) by driving four semiconductor lasers (not shown) based on image information sent from an external personal computer or scanner (not shown). Write lights Lk, Lm, Lc and Ly for C and Y are emitted. Then, while deflecting them by a polygon mirror (not shown), they are reflected by a reflection mirror (not shown) or passed through an optical lens to perform optical scanning on the photosensitive belt 11. Instead of such a configuration, an LED array that performs optical scanning may be used. The optical scanning is performed in the dark.

  The photosensitive belt 11 extends from the upper side to the lower side in the vertical direction between the lowermost driving roller 11b and the uppermost tension roller 11c among the plurality of stretching rollers that stretch the photosensitive belt 11 itself. Move almost straight toward you. In this process, first, when passing through a position facing the K charging device 2K, for example, it is uniformly charged to a negative polarity. Then, after carrying the electrostatic latent image for K by optical scanning with the writing light Lk for K, it passes through a position facing the developing device 6K for K. At this time, the electrostatic latent image for K written on the photosensitive belt 11 is developed by the developing device 6K for K to become a K toner image.

  The photosensitive belt 11 on which the K toner image is formed is uniformly charged again by the M charging device 2M in accordance with the movement from the upper side to the lower side in the vertical direction, and then the M writing light Lm. The electrostatic latent image for M is carried by the optical scanning by. The M electrostatic latent image is developed by the M developing device 6M to become an M toner image.

  The photosensitive belt 11 on which the M toner image is formed is uniformly charged again by the C charging device 2C in accordance with the movement from the upper side to the lower side in the vertical direction, and then the C writing light Lc. The electrostatic latent image for C is carried by the optical scanning by. The C electrostatic latent image is developed by the C developing device 6C to become a C toner image. At this time, the entire area or a partial area of the C toner image is developed in a state of being superimposed on the M toner image already formed on the photosensitive belt 11, and the overlapping position is determined by M and C. Secondary color part.

  The photosensitive belt 11 on which the C toner image is formed is uniformly charged again by the Y charging device 2Y as the vertical belt moves from the upper side to the lower side, and then the Y writing light Ly. The electrostatic latent image for Y is carried by the optical scanning by. The Y electrostatic latent image is developed by the Y developing device 6Y to become a Y toner image. At this time, the entire area or position area of the Y toner image is superimposed on the M toner image, the C toner image, or the secondary color portion of the MC already formed on the photosensitive belt 11. Thus, a secondary color portion by M and Y, a secondary color portion by C and Y, or a tertiary color portion by M, C, and Y is obtained.

  By superimposing and developing the K, M, C, and Y toner images as described above, a four-color superimposed toner image is formed on the front surface (loop outer surface) of the photoreceptor belt 11. As the charging devices 2 (K, M, C, Y) for K, M, C, and Y, those that uniformly charge the photosensitive belt 11 by corona discharge are used. According to the charging device 2 (K, M, C, Y) having such a configuration, it is possible to perform a uniform charging process on the photosensitive belt 11 in a non-contact manner, and thus a toner image already formed on the belt. Disturbance of the toner image due to contact with the toner can be avoided.

  When the photosensitive belt 11 that has passed through the developing position for Y, which is the position facing the developing device 6Y for Y, passes through the place where the photosensitive belt 11 is wound around the driving roller 11b, this time, the photosensitive belt 11 is now relatively upward from the lower side in the vertical direction. To move. Then, it enters the place where the secondary transfer backup roller 11a is wound. The secondary transfer roller 12 is in contact with the part of the hung portion from the front surface side to form a transfer nip. While the secondary transfer backup roller 11a is grounded, a transfer bias is applied to the conductive secondary transfer roller 12 by a bias applying means (not shown). Thus, the toner image on the photosensitive belt 11 is transferred from the secondary transfer backup roller 11a side to the secondary transfer roller between the secondary transfer backup roller 11a and the secondary transfer roller 12 sandwiching the transfer nip. A transfer electric field for electrostatic movement is formed on the 12 side.

  On the other hand, the paper feed cassette 50 feeds the recording paper P stored in the cassette toward the paper feed path 52 by rotating the paper feed roller 51 at a predetermined timing. The fed recording paper P is sandwiched between rollers of a registration roller pair 53 disposed below the transfer nip in the drawing. As soon as the registration roller pair 53 sandwiches the leading end of the recording paper P, the rotation of the registration roller 53 is temporarily stopped. Then, rotation driving is resumed at a timing at which the recording paper P can be synchronized with the four-color superimposed toner image on the photosensitive belt 11, and the recording paper P is sent to the transfer nip.

  The four-color superimposed toner image brought into intimate contact with the recording paper P at the transfer nip is collectively transferred from the belt to the recording paper P by the action of the nip pressure and the transfer electric field, and becomes a full color image combined with the white color of the recording paper P.

  The recording paper P on which a full-color image is formed in this way is sent to the fixing device 3 from the transfer nip. The fixing device 3 forms a fixing nip by contact between a fixing roller 3b containing a heat source such as a halogen lamp and a pressure roller 3a pressed against the fixing roller 3b. Is inserted into the fixing nip. Then, the full color image is fixed on the recording paper P by the action of the heating by the fixing roller 3b and the nip pressure.

  The recording paper P on which a full-color image is fixed in the fixing device 3 and a visible image is formed on the surface is discharged outside the apparatus after passing through a pair of discharge rollers (not shown).

  In the printer 100, no cleaning means is provided for cleaning the transfer residual toner adhering to the surface of the photosensitive belt 11 after passing through the transfer nip. The photosensitive belt 11 enters the development position for the next process K, M, C, and Y with the transfer residual toner attached, but the four charging devices 2 (K, M, and C). , Y) ensures that the untransferred toner is charged to the normal polarity, and is transferred to the recording paper P when entering the transfer nip again. Even if the transfer residual toner is transferred onto the recording paper P, the image quality deterioration to the extent that it is visually recognized does not occur as long as the amount is small.

  When the amount of transfer residual toner is relatively large, the transfer residual toner is removed from the surface of the photosensitive belt 11 after passing through the transfer nip and before entering the position facing the charging device 2K for K. Cleaning means may be provided. In this case, the cleaning unit and the developing device can be integrally configured as a process unit.

FIG. 3 is an explanatory diagram of one process unit 60 among the four process units 60 (K, M, C, Y). Each process unit 60 uses different colors of toner, but the other configurations are almost the same. Therefore, in the following description, K, M, C, and Y color coding symbols are omitted.
As shown in FIG. 3, the developing device 6 includes a casing 61 that forms a toner accommodating portion 66 that accommodates toner to be supplied to the photoreceptor belt 11, and a toner carrier that faces the photoreceptor belt 11 through an opening 90 of the casing 61. And a toner carrying roller 7 as a body. Further, the developing device 6 pumps the toner to the supply roller 62 while stirring the toner in the toner storage unit 66 and the supply roller 62 that is a toner supply unit that supplies the toner in the toner storage unit 66 to the toner carrying roller 7. And paddle 64. The toner carrying roller 7, the supply roller 62, and the paddle 64 are rotated by a rotation driving mechanism (not shown).

  The toner carrying roller 7 has a plurality of electrodes, which will be described in detail later, on the surface thereof, carries the toner in a cloud state by an electric field formed between the electrodes, and moves the toner to the photosensitive belt 11 by surface movement by rotational driving. It is transported to the developing position which is the opposite part. A blade-shaped regulating member 63 that regulates the amount of toner on the toner carrying roller 7 is installed upstream of the toner carrying roller 7 in the toner conveyance direction with respect to the development position. The regulating member 63 is in contact with the toner carrying roller 7, and when passing through the contact portion between the regulating member 63 and the toner carrying roller 7, the toner is caused by friction between the toner carrying roller 7 and the regulating member 63 and the toner. Charged. The regulating member 63 is not limited to a blade-like member, and a roller-like member may be brought into contact with the toner carrying roller 7.

  A toner storage unit 66 of the developing device 6 stores toner (not shown). The toner stored in the developing device 6 of this embodiment is as follows. Binder resin can be radically polymerized with styrene or acrylic polymerizable monomer dispersed in water together with polymerization initiator, or polymerized by polyaddition reaction with polyester resin dispersed in water. Let These are non-magnetic toner particles having a weight average particle diameter of about 5 [μm] obtained by adding a colorant, a charge control agent and the like to granulation.

Next, the toner carrying roller 7 will be described.
The toner carrying roller 7 is a roller-like toner carrying body having a plurality of electrodes therein in order to generate an electric field for conveying, developing, and collecting powder toner particles. The toner carrying roller 7 is opposed to the photosensitive belt 11 in a non-contact manner with a gap of 50 to 1000 [μm], preferably 150 to 400 [μm], at the time of image formation.

  FIG. 4 is a perspective view showing the toner carrying roller 7. The toner carrying roller 7 has a plurality of electrodes that extend in the roller axial direction and are arranged at a predetermined pitch in the roller circumferential direction on the circumferential surface of the roller portion. More specifically, as shown in FIG. 5, the plurality of electrodes are formed by alternately arranging A-phase electrodes 20a and B-phase electrodes 20b in the circumferential direction of the roller.

  As shown in FIG. 4, an A-phase common electrode 21a is provided at one end in the axial direction of the roller portion of the toner carrying roller 7 so as to extend over the entire circumference of the roller portion. One end portions of the plurality of A-phase electrodes 20a are connected to each other. Further, a B-phase common electrode 21b is provided at the other end of the roller portion in the axial direction so as to extend over the entire circumference of the roller portion, and this includes the other ends of the plurality of B-phase electrodes 20b. Each part is connected.

  For convenience, although not shown in FIGS. 4 and 5, a surface layer 22 made of a non-conductive material is coated on the plurality of A-phase electrodes 20a and B-phase electrodes 20b as shown in FIG. The surface layer 22 prevents contact between the electrodes and the toner. However, the surface layer 22 is not provided on the A-phase common electrode 21a and the B-phase common electrode 21b shown in FIGS. 4 and 5, and these common electrodes are exposed.

  An A-phase brush contact member (not shown) fixed to the casing 61 rubs against the A-phase common electrode 21 a that moves endlessly on the rotation track as the toner carrying roller 7 rotates. Then, the A-phase pulse voltage output from the power source 24 shown in FIGS. 4 and 6 is applied to each A-phase electrode 20a via the A-phase brush contact member and the A-phase common electrode 21a. Further, a B-phase brush contact member (not shown) fixed to the casing rubs against the B-phase common electrode 21b that moves endlessly on the rotation track as the toner carrying roller 7 rotates. The B-phase pulse voltage output from the power supply 24 is applied to each B-phase electrode 20b via the B-phase brush contact member and the B-phase common electrode 21b.

  Hereinafter, a set of a plurality of A-phase electrodes 20a to which the A-phase pulse voltage is applied is referred to as an A-phase electrode group. A set of a plurality of B phase electrodes 20b to which a B phase pulse voltage is applied is referred to as a B phase electrode group. Since the A-phase electrodes 20a and the B-phase electrodes 20b are alternately arranged, the arrangement order of the plurality of A-phase electrodes 20a from the predetermined position in the roller circumferential direction is odd or even. The arrangement order of the plurality of B-phase electrodes 20b is even when the arrangement order of the A-phase electrodes 20a is odd, and is even when the arrangement order of the A-phase electrodes 20a is even. .

For example, a rectangular wave-shaped A-phase pulse voltage Va that repeats rising and falling at a predetermined cycle as shown in FIG. 7 is applied to the A-phase electrode group. On the other hand, a rectangular wave-shaped B-phase pulse voltage Vb whose rising and falling phases are opposite to the A-phase pulse voltage Vb is applied to the B-phase electrode group, for example, as shown in FIG. The period T, frequency f (f = 1 / T), peak-to-peak voltage Vpp, and amplitude center potential Vc of each pulse voltage are the same. When such a pulse voltage is applied, the toner on the toner carrying roller 7 floats from directly above the A-phase electrode 20a and lands on the adjacent B-phase electrode 20b so as to draw a parabola. The reciprocating movement by hopping is repeated such that it floats right above the B-phase electrode 20b and returns to the adjacent A-phase electrode 20a so as to draw a parabola.
As described above, the power supply 24 is a voltage supply unit that supplies a voltage so that the electric field between the plurality of electrodes (the A-phase electrode 20a and the B-phase electrode 20b) changes with time.

  As described above, the toner that has been reciprocated by hopping in this way is conveyed to the developing position by the rotational driving of the toner carrying roller 7. At the development position, the toner that reaches the vicinity of the electrostatic latent image on the photosensitive belt 11 near the apex of the parabolic hopping locus deviates from the hopping locus while being attracted by the electrostatic force of the electrostatic latent image. And adhere to the electrostatic latent image. On the other hand, the toner that reaches the vicinity of the background portion (uniformly charged portion) of the photosensitive belt 11 near the apex of the parabolic hopping locus descends without departing from the hopping locus, and the surface of the toner carrying roller 7. Land on.

  In such a configuration, by using toner in a state in which the adsorbing force with the toner carrying roller 7 is released by hopping, a low potential that cannot be realized by the conventional one-component development method or the two-component development method. Development can be realized. Hereinafter, as in the printer 100 of the present embodiment, a method of performing development by transferring toner to the development region by moving the surface of the toner carrier while reciprocating the toner between the electrodes of the toner carrier by hopping (Flare). ) Development method.

  As the A-phase pulse voltage Va and the B-phase pulse voltage Vb, the peak-to-peak voltage Vpp is 200 to 1000 [V], the frequency f is 0.1 to 5 [kHz], and the amplitude central potential Vc. Is between the latent image potential on the photosensitive belt 11 and the background potential. The amplitude center potential Vc varies depending on conditions between the latent image potential and the background portion potential. The phases of A phase and B phase are shifted from each other by ½ period. Thereby, during application of the pulse voltage, a potential difference having a value equal to Vpp is always generated between the A-phase electrode 20a and the B-phase electrode 20b. Due to this potential difference, an electric field is generated between the electrodes, and the toner hops between the electrodes in accordance with the electric field.

  As a combination of two pulse voltages applied to the A-phase electrode group and the B-phase electrode group, in addition to the combinations shown in FIG. 7, the A-phase pulse voltage Va composed of a rectangular wave and the amplitude that is the center value of the amplitude thereof A combination with a DC voltage Vb composed of the center potential Vc may be employed. Further, the relationship between the A phase and the B phase in this combination may be reversed. Further, as the waveform of the pulse voltage, other than a rectangular wave, for example, a sine wave, a triangular wave having a time constant, a sine wave corresponding to the time constant, or the like may be employed.

  As shown in FIG. 6, on the surface of the support substrate 23, a plurality of electrodes (20a, 20b) are arranged at predetermined intervals along the toner conveyance direction. An inorganic or organic insulating material which is a transport surface forming member on these electrodes and on the non-electrode forming surface of the support substrate 23 and serves as a protective film covering the surfaces of the electrodes (20a, 20b). The surface layer 22 formed from is coated.

Examples of the support substrate 23 include base materials made of an insulating material such as a glass base material, a resin base material, and a ceramic base material. Further, a substrate made of a conductive material such as stainless steel and an insulating film such as SiO ₂ may be formed, or a base material made of a material that can be deformed flexibly such as a polyimide film may be used.

  The A-phase electrode 20a and the B-phase electrode 20b are formed as follows, for example. That is, a film having a thickness of 0.1 to 10 [μm], preferably 0.5 to 2.0 [μm] made of a conductive material such as Al or Ni—Cr is formed on the surface of the support substrate 23. Then, this film is formed by patterning into a required electrode shape by a photolithography method or the like. And after forming each electrode, the surface layer 22 is formed on it. The width (length in the short direction) of each electrode (20a, 20b) is desirably 1 to 20 times the average particle diameter of the toner particles.

As the surface layer 22, for example, a material such as SiO ₂ , TiO ₂ , TiO ₄ , SiON, BN, TiN, Ta ₂ O ₅ is used with a thickness of 0.5 to 10 [μm], preferably 0.5 to 3 [ [mu] m] can be exemplified.

  As shown in FIG. 5, the A-phase common electrode 21a and the B-phase common electrode 21b can be formed by the same method as the A-phase electrode 20a and the B-phase electrode 20b. In addition to the A-phase electrode 20a and the B-phase electrode 20b, it can be formed as follows. That is, as shown in FIG. 8, the flange member 25 made of metal is press-fitted from the end in the axial direction into the roller portion on which the A-phase electrode and the B-phase electrode of the toner carrying roller 7 are formed. 25 is connected to the end of the A-phase electrode or B-phase electrode on the roller section. The metal surface of the flange member 25 is used as a common electrode. As the flange member 25, it is desirable to use a member integrally formed with the rotating shaft member of the toner carrying roller 7 as shown in the figure.

  By the way, in the conventional two-component development method, development is performed while rubbing the toner adhering to the surface of the magnetic carrier magnetically attracted to the developer carrying member together with the magnetic carrier onto the latent image carrying member. Further, in the conventional one-component development system, the toner carried on the surface of the developer carrying member is rubbed against the latent image carrying member, or the toner on the developer carrying member arranged in non-contact with the latent image carrying member. The image is reciprocated between the developer carrying member and the latent image carrying member by an alternating electric field. In these methods, when overlay development is performed as in the printer 100 of the present embodiment, the toner in the toner image previously developed on the latent image carrier is developed in the subsequent color during the subsequent development. Transfers into the device and causes color mixing.

  On the other hand, in the printer 100 of this embodiment, development is performed without causing the toner on the toner carrying roller 7 to rub against the photosensitive belt 11. Further, the toner does not reciprocate between the surface of the photoreceptor belt 11 and the surface of the toner carrying roller 7 by an alternating electric field, and the hopped toner that does not contribute to development is brought into contact with the photoreceptor belt 11. Return to the toner carrying roller 7 without any change. In addition, the toner that has contributed to the electrostatic latent image on the photosensitive belt 11 is not transferred again onto the toner carrying roller 7. As a result, it is possible to avoid color mixing in the developing device for subsequent colors.

Next, the developing device 6 will be described in more detail.
FIG. 9 is an explanatory diagram of the developing device 6 including a characteristic portion in the opening 90 according to the present embodiment.
As described with reference to FIG. 3, the casing 61 of the developing device 6 forms the opening 90 at the developing position where the toner carrying roller 7 faces the photosensitive belt 11. Further, the toner carrying roller 7 is rotated counterclockwise in FIG. 9 (in the direction of arrow B in FIG. 9) by a driving means (not shown).

An end portion of the opening 90 on the downstream side in the rotation direction of the toner carrying roller 7 is an inlet portion 8 through which the toner that has passed the developing position enters the casing 61. The inlet portion 8 is formed by a casing inlet side end portion 61 a which is an end portion of the casing 61 on the inlet portion 8 side and the surface of the toner carrying roller 7. The width of the gap of the inlet portion 8 that is the distance from the casing inlet side end portion 61a to the surface of the toner carrying roller 7 is the inlet width Wa.
The end of the opening 90 on the upstream side in the rotation direction of the toner carrying roller 7 is an outlet 9 that is carried by the toner carrying roller 7 and goes out of the casing 61 toward the developing position. The outlet portion 9 is formed by a casing outlet side end portion 61 b which is an end portion of the casing 61 on the outlet portion 9 side and the surface of the toner carrying roller 7. The width of the gap of the outlet 9 that is the distance from the casing outlet side end 61b to the surface of the toner carrying roller 7 is the outlet width Wb.

The toner supplied to the surface of the toner carrying roller 7 by the supply roller 62 is thinned by the regulating member 63 and frictionally charged, and then becomes a cloud state by the electric field between the electrodes formed on the surface of the toner carrying roller 7. It is conveyed from the gap of the exit portion 9 to the development position. The toner particles that have not contributed to the development at the development position are transported to a position where the supply roller 62 contacts again through the gap of the inlet portion 8.
The developing device 6 of the present embodiment is set so that the inlet width Wa ≧ cloud height H.
Here, the cloud height H is the height to the highest point where the toner reaches when the toner hops between the electrodes due to the electric field between the electrodes formed on the surface of the toner carrying roller 7.

Note that the height of the highest point when the toner is hopped varies depending on the particle diameter and weight of the toner, the charge amount, the strength of the electric field, and the like. The printer 100 uses toner having a weight average particle diameter of about 5 [μm]. However, the particle diameter and charge amount of each toner particle vary, and the height of the highest point when hopping also varies. Arise.
In the present embodiment, toner is conveyed by the toner carrying roller 7 using an experimental machine using the toner carrying roller 7 and the toner particles under the same conditions as those used in the printer 100, and this toner conveyance is photographed by a high-speed camera. To do. Then, the behavior of each toner particle was observed from the image taken by the high-speed camera, the height of the highest point of each toner particle was measured, and the average value was taken as the cloud height H.

Here, when the inlet width Wa <cloud height H, the influence of the electric field is low near the highest point when the toner hops between the electrodes, so the electric field is not released by a slight impact and does not pass through the inlet 8. Toner is scattered. Therefore, by using the casing 61 that satisfies the inlet width Wa ≧ cloud height H, the toner particles in the cloud state can be smoothly introduced into the casing 61 from the inlet portion 8, and the toner cannot pass through the inlet portion 8. It is possible to suppress toner scattering due to this.
Further, since the developing device 6 of the present embodiment is provided with toner backflow prevention means, which will be described in detail in the following examples, the toner remains in the casing even if the inlet width Wa is set wider than the cloud height H. It is possible to prevent going from the inside 61 to the entrance 8. For this reason, it is possible to prevent toner scattering due to the backflow of toner at the inlet, and thus toner scattering can be prevented more reliably.

Further, in the developing device 6 of the present embodiment, the inlet width Wa that is the width of the gap of the inlet portion 8 and the outlet width Wb that is the width of the gap of the outlet portion 9 are such that the inlet width Wa ≧ the outlet width Wb. Is set.
The toner particles in the cloud state on the surface of the toner carrying roller 7 are conveyed from the exit portion 9 to the development position. By setting the inlet width Wa ≧ the outlet width Wb, the cloud height H is adjusted when passing through the outlet portion 9, so that the toner in the cloud state that has passed the developing position enters the casing 61 from the inlet portion 8. It becomes easy. This suppresses the overall cloud height H, and can regulate the toner that irregularly hops due to variations in toner characteristics at the outlet 9.
In addition, it is conceivable to adjust the cloud height H at a position upstream of the toner carrying roller 7 in the toner conveying direction with respect to the outlet portion 9, but by restricting at the outlet portion 9 which is an end portion of the casing 61, It is easier to obtain regulatory effects. This is because the more the position where the cloud height H is regulated is upstream in the toner conveyance direction with respect to the inlet portion 8, the more the number of electrodes that pass before the toner passing through the regulated position reaches the inlet portion 8. This is because the width of variation in the height of the highest point of toner hopping is widened.

[Example 1]
Next, a first embodiment (hereinafter referred to as Embodiment 1) of the developing device 6 provided with toner backflow prevention means will be described.
FIG. 10 is an explanatory diagram of the developing device 6 according to the first embodiment.
In the developing device 6 according to the first exemplary embodiment, the toner backflow preventing unit prevents the toner from moving from the inner side of the casing 61 toward the inlet portion 8 on the downstream side in the toner conveyance direction of the toner carrying roller 7 with respect to the inlet portion 8. The sheet member 65 that is a carrier-facing member is provided. The sheet member 65 is made of a sheet-like elastic member, and the surface thereof is opposed to the surface of the toner carrying roller 7, and the distance between the surfaces is arranged closer to the downstream side of the toner carrying roller 7 in the toner conveyance direction. The edge, which is the downstream end of the sheet member 65 in the toner conveyance direction, is preferably slightly separated from the surface of the toner carrying roller 7, but may be in contact therewith. It is desirable that the sheet member 65 be as close as possible to the supply roller 62 as far as possible from the inlet portion 8. Then, the toner in the cloud state that has passed through the inlet portion 8 collides with the sheet member 65 and falls onto the supply roller 62 and is collected in the toner storage portion 66.

Further, as illustrated in FIG. 10, the developing device 6 according to the first exemplary embodiment forms an inlet space 70 between the inlet portion 8 and the position where the sheet member 65 is provided around the toner carrying roller 7. The entrance space 70 has a width in the normal direction of the surface of the toner carrying roller 7, that is, the gap between the toner carrying roller 7 and the inner wall of the casing 61 is wider than the entrance width Wa. Some of the toner in the cloud state that has passed through the inlet portion 8 collides with the sheet member and is bounced back.
In addition, by providing the sheet member 65, it is possible to suppress the flow of air from the inlet portion 8 toward the toner storage portion 66, and to suppress an increase in the internal pressure of the toner storage portion 66. However, the internal pressure rises in the space between the sheet member 65 and the inlet portion 8, and there is a possibility that the toner in the cloud state bounced back to the sheet member 65 may be ejected from the inlet portion 8. On the other hand, by forming the entrance space 70, the space between the surface of the toner carrying roller 7 and the inner surface of the casing 61 is uniform with the entrance width Wa or narrower than the entrance width Wa. Further, the amount of increase in the internal pressure on the upstream side of the sheet member 65 with respect to the amount of air flowing in from the inlet portion 8 can be suppressed. The sheet member 65 can suppress the internal pressure from increasing in the space between the sheet member 65 and the inlet portion 8 and can relieve the internal pressure, so that the ejection of toner can be prevented.

  As shown in FIG. 10, in the developing device 6 according to the first embodiment, an inlet seal 67 having one end fixed to the casing inlet side end 61a and the other end being a free end is provided at the inlet portion 8 at the toner carrying roller. 7 is provided along the axial direction of the rotating shaft. The entrance seal 67 and the surface of the photosensitive belt 11 are slightly separated from each other. Further, an outlet seal 68 having one end fixed to the casing outlet side end portion 61 b of the outlet portion 9 and a free end at the other end is provided along the axial direction of the rotation shaft of the toner carrying roller 7. The outlet seal 68 and the surface of the photoreceptor belt 11 are slightly separated from each other. As described above, the entrance seal 67 and the exit seal 68 that are slightly separated from the photosensitive belt 11 are provided, so that the space between the developing device 6 and the photosensitive belt 11 at the development position is almost hermetically sealed. Is preventing.

As shown in FIG. 10, the free end of the inlet seal 67 is farther from the surface of the toner carrying roller 7 than the casing inlet side end portion 61a. In the configuration including such an inlet seal 67, the configuration described with reference to FIG. 9 is used if the width between the free end of the inlet seal 67 and the surface of the toner carrying roller 7 is set wider than the cloud height. Similarly, the scattering of toner due to the inability of the toner to pass through the inlet portion 8 can be suppressed. At this time, the width between the free end of the inlet seal 67 and the surface of the toner carrying roller 7 can be regarded as the inlet width Wa.
Further, as in the configuration described with reference to FIG. 9, the entrance seal as shown in FIG. 10 has a configuration in which the width between the casing inlet side end portion 61a and the surface of the toner carrying roller 7 is set wider than the cloud height. 67 may be provided. In this case, since the toner having the highest toner hopping point higher than the average can be guided into the casing 61 by the inlet seal 67, the scattering of the toner can be prevented more reliably.
Further, the outlet seal 68 is arranged so that the gap between its free end and the surface of the toner carrying roller 7 is narrower than the inlet width Wa. As a result, similarly to the case where the inlet width Wa ≧ the outlet width Wb, the toner in the cloud state that has passed through the developing position easily enters the casing 61 from the inlet portion 8. Further, by providing the outlet seal 68, the position where the cloud height H on the outlet portion 9 side is regulated can be brought closer to the inlet portion 8 side, and the regulation effect can be easily obtained.

[Example 2]
Next, a second embodiment (hereinafter referred to as a second embodiment) of the developing device 6 having toner backflow prevention means will be described.
FIG. 10 is an explanatory diagram of the developing device 6 according to the second embodiment.
Similar to the first embodiment, the developing device 6 according to the second embodiment includes a sheet member 65 as a toner backflow preventing unit, and is provided with an outlet space 71 between the outlet portion 9 and the regulating member 63. Different from Example 1. In the exit space 71, the width in the normal direction of the surface of the toner carrying roller 7 from the surface of the toner carrying roller 7 to the surface of the inner wall of the casing 61 is wider than the exit width Wb.
The weakly charged toner that has passed through the regulating member 63 leaves the cloud electric field and falls onto the inner wall surface of the casing 61 to accumulate. As in the second embodiment, by forming the outlet space 71, toner that has passed through the regulating member 63 and dropped onto the inner wall surface of the casing 61 can be stored in the outlet space 71. Thereby, it is possible to prevent the toner that has fallen on the inner wall surface of the casing 61 from leaking out from the outlet portion 9 and being scattered. The toner that has fallen into the exit space 71 is a toner that does not exhibit a desired behavior on the toner carrying roller 7 due to insufficient charging or for other reasons. For example, a configuration in which the developer is stored in the outlet space 71 until the developing device 6 is replaced due to the life of the device or a configuration in which the waste toner is transported from the outlet space 71 to a container for collecting waste toner.

Example 3
Next, a third embodiment (hereinafter referred to as a third embodiment) of the developing device 6 provided with toner backflow prevention means will be described.
FIG. 12 is an explanatory diagram of the developing device 6 according to the third embodiment.
As shown in FIG. 12, the developing device 6 according to the third exemplary embodiment has a toner seal 69 disposed so as to contact the supply roller 62. An inlet space 70 is formed between the inlet portion 8 and the toner seal 69 around the toner carrying roller 7.
In addition, the inlet space 70 of the developing device 6 according to the third exemplary embodiment is provided with a communication port in the casing 61 that communicates with the outside of the casing 61, and a filter 75 that prevents toner from passing through the communication port. Yes. By providing a communication port in a part of the portion of the casing 61 forming the inlet space 70 and disposing the filter 75 there, the air in the inlet space 70 can be vented to the outside of the casing 61. As a result, an increase in pressure in the inlet space 70 can be suppressed, and the ejection of toner from the inlet portion 8 can be prevented.
Note that a communication port is provided in a portion of the casing 61 where the inlet space 70 is formed, and the filter 75 is provided in the communication port. As in the first and second embodiments, the surface of the toner seal 69 is a toner carrying roller. It is applicable also to the structure arrange | positioned so that 7 surface may be opposed.

Further, in the developing device 6 of the third embodiment, an electrode member 76 is disposed in the vicinity of the inlet portion 8 of the inlet space 70 along the rotation axis direction of the toner carrying roller 7. When a bias having a polarity opposite to the charging potential of the toner is applied to the electrode member 76, the toner separated from the cloud electric field in the vicinity of the inlet portion 8 by the electric field generated by the electrode member 76 can be taken into the inlet space 70. Toner scattering can be prevented.
The configuration in which the electrode member 76 is provided in the entrance space 70 can also be applied to the first and second embodiments.

Further, in the developing device 6 of the third embodiment, the inlet seal 67 and the outlet seal 68 are arranged at the inlet portion 8 and the outlet portion 9 as in the first embodiment.
In the developing device 6 of Example 3, the inlet seal 67 and the outlet seal 68 are formed of a conductive material and are electrically installed on the ground. As a result, the entrance seal 67 and the exit seal 68 are not charged, so that the adhesion of toner is suppressed, and the occurrence of toner scattering due to the fall of the toner that accumulates and falls as the toner adheres to the seal can be prevented.
In addition, the inlet seal 67 and the outlet seal 68 may be formed of a conductive material, and a bias having the same polarity as the charging potential of the toner may be applied. As a result, each seal and the toner are electrically repelled, so that the toner adhesion is suppressed, and the occurrence of toner scattering due to the dropping of the toner that accumulates and falls as the toner adhering to the seal accumulates can be prevented.
The configuration in which the inlet seal 67 and the outlet seal 68 are formed of a conductive material, and each seal is electrically grounded, or a bias having the same polarity as the charging potential of the toner is applied to each seal is an example. 1 and Example 2 are also applicable.

Example 4
Next, a fourth embodiment (hereinafter referred to as a fourth embodiment) of the developing device 6 provided with toner backflow prevention means will be described.
FIG. 13 is an explanatory diagram of the developing device 6 according to the fourth embodiment.
Similarly to the third embodiment, the developing device 6 according to the fourth embodiment includes a toner seal 69, a filter 75, and an electrode member 76 as a toner backflow prevention unit, and an outlet space 71 is provided between the outlet portion 9 and the regulating member 63. This is different from Example 3 in that it is formed. The weakly charged toner that has passed through the regulating member 63 leaves the cloud electric field and falls onto the inner wall surface of the casing 61 to accumulate. As in the second embodiment, by forming the outlet space 71, toner that has passed through the regulating member 63 and dropped onto the inner wall surface of the casing 61 can be stored in the outlet space 71. Thereby, it is possible to prevent the toner that has fallen on the inner wall surface of the casing 61 from leaking out from the outlet portion 9 and being scattered.
Further, since the internal pressure can be relieved by providing the exit space 71, the ejection of toner from the exit portion 9 can be eliminated.

Example 5
Next, a fifth embodiment (hereinafter referred to as embodiment 5) of the developing device 6 provided with toner backflow prevention means will be described.
FIG. 14 is an explanatory diagram of the process unit 60 according to the fifth embodiment.
As shown in FIG. 14, the developing device 6 of the fifth embodiment has the above-described first to sixth embodiments in that the surface movement direction of the toner carrying roller 7 at the development position is the same as the surface movement direction of the photosensitive belt 11. 4 different from the developing device 6. The toner carrying roller 7 of the developing device 6 of Example 5 is rotated clockwise in FIG. 14 (in the direction of arrow C in FIG. 14) by a driving unit (not shown).

FIG. 15 is an explanatory diagram of the developing device 6 according to the fifth embodiment.
The toner supplied to the surface of the toner carrying roller 7 by the supply roller 62 is thinned by the regulating member 63 and frictionally charged, and then becomes a cloud state by the electric field between the electrodes formed on the surface of the toner carrying roller 7. It is conveyed from the gap of the exit portion 9 to the development position. The toner particles that have not contributed to the development at the development position are transported to a position where the supply roller 62 contacts again through the gap of the inlet portion 8.
In the developing device 6 of Example 5, a toner seal 69 is provided between the inlet portion 8 and the supply roller 62 around the toner carrying roller 7. The toner seal 69 is made of a sheet-like member, and is in contact with the surface of the toner carrying roller 7 so as to block the toner T stored in the toner storage portion 66. The contact pressure of the toner seal 69, which is a seal member, with respect to the toner carrying roller 7 is such that the toner particles contacting the surface of the toner carrying roller 7 can pass through the endlessly moving surface of the toner carrying roller 7 and the portion where the toner seal 69 contacts. The contact pressure is such that the toner T in the toner container 66 can be prevented from flowing backward.
In this way, by blocking the toner with the toner seal 69, it is possible to prevent the toner from going from the casing 61 toward the inlet portion 8.

Here, in the developing device 6 of the fifth embodiment, the contact line pressure of the restriction member 63 on the surface of the toner carrying roller 7 necessary for the toner thinning by the restriction member 63 is defined as a restriction member contact pressure Fb. On the other hand, assuming that the contact line pressure of the toner seal 69 provided between the inlet portion 8 and the supply roller 62 around the toner carrying roller 7 on the surface of the toner carrying roller 7 is the inlet internal seal contact pressure Fa, the developing device 6. Is
Inlet inner seal contact pressure Fa ≦ regulating member contact pressure Fb
Satisfy the relationship. By setting in this way, the toner that has passed through the regulating member 63 and has been thinned is again easily passed through the toner seal 69 and conveyed to a position where the supply roller 62 contacts the toner carrying roller 7.

Example 6
Next, a sixth embodiment (hereinafter referred to as embodiment 6) of the developing device 6 provided with toner backflow prevention means will be described.
FIG. 16 is an explanatory diagram of the developing device 6 according to the sixth embodiment.
In the developing device 6 of the sixth embodiment, the surface movement direction at the developing position of the toner carrying roller 7 is the same as the surface movement direction of the photosensitive belt 11 as in the fifth embodiment, and serves as a toner backflow prevention unit. A toner seal 69 is provided. The second embodiment is different from the fifth embodiment in that an inlet space 70 is formed between the inlet portion 8 and the toner seal 69. By providing the entrance space, the internal pressure raised by the toner seal 69 can be relieved as in the first embodiment, and the ejection of toner can be prevented.
Further, among the toners that bounce off the toner seal 69, the weakly charged toner leaves the cloud electric field and drops onto the inner wall surface of the casing 61 and accumulates. As in the sixth embodiment, by forming the inlet space 70, the toner that has collided with the toner seal 69 and dropped onto the inner wall surface of the casing 61 can be stored in the inlet space 70. Accordingly, it is possible to prevent the toner that has fallen on the inner wall surface of the casing 61 from leaking out from the inlet portion 8 and being scattered as in the second embodiment in which the outlet space 71 is provided.

  Further, in the developing device 6 according to the sixth embodiment, an inlet seal 67 and an outlet seal 68 are arranged at the inlet portion 8 and the outlet portion 9 as in the first embodiment. For the inlet seal 67 and the outlet seal 68, as in the third embodiment, the inlet seal 67 and the outlet seal 68 are formed of a conductive material, and each seal is electrically grounded, or the charging potential of the toner is applied to each seal. Alternatively, a bias having the same polarity may be applied. Thereby, the adhesion of the toner to each seal is suppressed, and it is possible to prevent the occurrence of toner scattering due to the fall of the toner that accumulates and falls as the toner adhering to the seal accumulates.

  Up to now, an example of an apparatus in which toner is reciprocated by hopping on the surface of a toner carrying roller as a toner carrying member has been described. However, instead of reciprocating movement, hopping may be performed only in a certain direction. . In this case, it is possible to individually apply pulse voltages of three or more phases to three or more electrodes that are arranged in order, and hop the toner along the direction of the arrangement order.

  The present invention can also be applied to a color image forming apparatus, a monochrome image forming apparatus, and the like using an intermediate transfer belt, a transfer drum, an intermediate transfer drum, and the like.

  As described above, according to the present embodiment, the developing device 6 includes the toner carrying roller 7 that is a toner carrying body including a plurality of electrodes (A-phase electrode 20a and B-phase electrode 20b) arranged in a predetermined direction. Further, the toner carrying roller 7 has a supply roller 62 as toner supply means for supplying toner to the endlessly moving surface. Further, a toner accommodating portion 66 that accommodates toner to be supplied to the toner carrying roller 7 is formed, and a casing 61 that is a developing casing including the toner carrying roller 7 and the supply roller 62 inside is provided. The toner carrying roller 7 is opposed to the photosensitive belt 11 which is a latent image carrier at an opening 90 formed in a part of the casing 61. Further, the developing device 6 causes the toner carried on the surface of the toner carrying roller 7 to hop on the surface by an electric field formed by applying a voltage to the plurality of electrodes, thereby setting the cloud state. Then, while the toner is in a cloud state, the toner is conveyed to a developing position where the toner carrying roller 7 and the photosensitive belt 11 are opposed to each other, and the toner is attached to the latent image carried on the photosensitive belt 11 at the developing position. Develop the image. The toner that has passed through the developing position without adhering to the photosensitive belt 11 is conveyed into the casing 61 in a cloud state. Here, the distance from the casing inlet side end portion 61a that is the end portion of the casing 61 that forms the inlet portion 8 that is the downstream end portion of the toner carrying roller 7 in the toner conveying direction of the opening 90 to the surface of the toner carrying roller 7. Is set to satisfy the relationship of inlet width Wa ≧ cloud height H, where the height of the toner in the cloud state on the surface of the toner carrying roller 7 is the cloud height H. Accordingly, the toner particles in the cloud state can be smoothly introduced into the casing 61 from the inlet portion 8, and toner scattering due to the fact that the toner cannot pass through the inlet portion 8 can be suppressed. Further, the developing device 6 prevents the toner from moving from the inner side of the casing 61 toward the inlet portion 8 on the downstream side in the toner transport direction of the toner carrying roller 7 with respect to the inlet portion 8. The toner backflow prevention means is provided. Therefore, even if the entrance width Wa is set wider than the cloud height H, the toner can be prevented from going from the casing 61 toward the entrance portion 8. For this reason, it is possible to prevent toner scattering due to the backflow of toner at the inlet, and thus toner scattering can be prevented more reliably.

  The developing device 6 according to the first and second embodiments includes a sheet member 65 that is a carrier-facing member as a toner backflow prevention unit. The sheet member 65 is disposed such that the surface thereof faces the surface of the toner carrying roller 7 and the distance between the surface of the sheet carrying member 7 and the toner carrying roller 7 is closer to the downstream side of the toner carrying roller 7 in the toner conveying direction. Thus, the toner in the cloud state that has entered from 8 can be easily introduced into the casing 61. Further, the downstream end portion of the sheet member 65 in the toner conveying direction narrows the space from the inlet portion 8 toward the inside of the casing 61, and therefore moves from the inlet portion 8 toward the toner accommodating portion 66 along with the movement of the surface of the toner carrying roller 7. It is possible to suppress the amount of air and suppress an increase in pressure in the toner containing portion 66. For this reason, it is possible to suppress the flow of air from the developing casing toward the opening, and it is possible to prevent the backflow of toner from the toner storage portion 66 toward the inlet portion 8.

  Further, the developing device 6 of the fifth and sixth embodiments includes a toner seal 69 that is an inlet internal seal member that contacts the toner carrier as a toner backflow prevention unit. The contact pressure of the toner seal 69 with respect to the toner carrying roller 7 is such that the toner particles contacting the surface of the toner carrying roller 7 can pass through the portion where the toner seal contacts with the endlessly moving surface of the toner carrying roller 7, and the toner container The contact pressure is such that the toner T in 66 can be prevented from flowing backward. By providing such a toner seal 69, the movement of the air from the inlet portion 8 toward the toner storage portion 66 is suppressed along with the movement of the surface of the toner carrying roller 7, and the increase in pressure in the toner storage portion 66 is suppressed. Can do. For this reason, it is possible to suppress the flow of air from the developing casing toward the opening, and it is possible to prevent the backflow of toner from the toner storage portion 66 toward the inlet portion 8. Further, the toner seal 69 is brought into contact with the surface of the toner carrying roller 7 and is arranged so as to block the toner T contained in the toner containing portion 66, whereby the inlet portion 8 is opened as in the fifth and sixth embodiments. Even in the configuration below the portion 90, the leakage of toner from the opening 90 can be prevented.

  In the fifth and sixth embodiments, the toner carrying roller 7 is positioned on the upstream side in the toner carrying direction of the toner carrying roller 7 from the outlet portion 9 which is the upstream end of the toner carrying roller 7 in the opening 90 in the toner carrying direction. And a regulating member 63 that is a toner regulating member that regulates the toner layer. Here, the contact line pressure of the toner seal 69 to the surface of the toner carrying roller 7 is defined as the inlet inner seal contact pressure Fa, and the contact pressure of the regulation member 63 to the surface of the toner carrying roller 7 is defined as the regulation member contact pressure Fb. To do. At this time, the developing device 6 satisfies the relationship of the inlet inner seal contact pressure Fa ≦ the restriction member contact pressure Fb. In this way, by setting the inlet inner seal contact pressure Fa to be lower than the restriction member contact pressure Fb, the toner that has passed through the restriction member 63 and has been thinned can easily pass through the toner seal 69 and again. It is possible to return to the position where the supply roller 62 contacts the toner carrying roller 7.

  Further, in the developing devices 6 of the first and second embodiments, the toner carrying roller 7 is located downstream in the toner carrying direction with respect to the inlet 8 and the toner carrying roller 7 is located in the toner carrying direction upstream with respect to the position where the sheet member 65 is disposed. In addition, an entrance space 70 is formed. In the entrance space 70, the width of the surface of the toner carrying roller 7 in the normal direction is wider than the entrance width Wa. In the configuration including the sheet member 65 that narrows the width of the space between the surface of the toner carrying roller 7 and the inner surface of the casing 61 as in the first and second embodiments, the internal pressure in the space upstream of the sheet member 65 in the toner conveyance direction. May rise and cause toner scattering. On the other hand, by forming the inlet space 70, the space between the surface of the toner carrying roller 7 and the inner surface of the casing 61 is more uniform from the inlet portion 8 than that having a uniform or narrower inlet width Wa. The amount of increase in internal pressure upstream of the sheet member 65 with respect to the inflow amount of the air can be suppressed. As described above, since the internal pressure in the space downstream of the toner carrying roller 7 in the toner transport direction from the inlet portion 8 can be relieved, it is possible to suppress the suppression of toner ejection.

  Further, in the developing devices 6 according to the fifth and sixth embodiments, the toner carrying roller 7 is located downstream in the toner carrying direction with respect to the inlet 8, and the toner carrying roller 7 is located in the toner carrying direction upstream with respect to the position where the toner seal 69 is disposed. In addition, an entrance space 70 is formed. In the entrance space 70, the width of the surface of the toner carrying roller 7 in the normal direction is wider than the entrance width Wa. In the configuration including the toner seal 69 in contact with the toner carrying roller 7 as in the fifth and sixth embodiments, the internal pressure in the space on the upstream side in the toner conveyance direction with respect to the toner seal 69 may increase, and the toner may be scattered. . On the other hand, by forming the inlet space 70, the space between the surface of the toner carrying roller 7 and the inner surface of the casing 61 is more uniform from the inlet portion 8 than that having a uniform or narrower inlet width Wa. The amount of increase in internal pressure upstream of the toner seal 69 relative to the inflow amount of the toner can be suppressed. As described above, since the internal pressure in the space downstream of the toner carrying roller 7 in the toner transport direction from the inlet portion 8 can be relieved, it is possible to suppress the suppression of toner ejection.

  Even when the sheet member 65 and the toner seal 69 are not provided, by forming the inlet space 70, the space between the surface of the toner carrying roller 7 and the inner surface of the casing 61 is uniform with the inlet width Wa. Alternatively, the amount of increase in internal pressure upstream of the toner seal 69 with respect to the amount of inflow of air from the inlet 8 can be suppressed as compared with the narrowed configuration. As described above, since the internal pressure in the space downstream of the toner carrying roller 7 in the toner transport direction from the inlet portion 8 can be relieved, it is possible to suppress the suppression of toner ejection.

  In addition, the developing device 6 according to the third and fourth embodiments includes an electrode member 76 in which a bias having a polarity opposite to the charging potential of the toner is applied to the entrance space 70. Accordingly, when a bias having a polarity opposite to the charging potential of the toner is applied to the electrode member 76, the toner separated from the cloud electric field in the vicinity of the inlet portion 8 by the electric field generated by the electrode member 76 can be taken into the inlet space 70, and the inlet portion Toner scattering at 8 can be prevented.

  Further, even in the developing device 6 having a configuration in which the entrance space 70 is not formed, the toner carrying roller 7 is transported from the entrance 8 by the electrode member 76 to which a bias having a polarity opposite to the charging potential of the toner is applied. You may arrange | position in the direction downstream side. When a bias having a polarity opposite to the charging potential of the toner is applied to the electrode member 76, the toner separated from the cloud electric field in the vicinity of the inlet portion 8 by the electric field generated by the electrode member 76 can be taken into the inlet space 70. Toner scattering can be prevented.

  Further, the developing device 6 according to the third and fourth embodiments includes a communication port that connects the inlet space 70 and the outside of the casing 61, and a filter 75 that is a filter member that prevents toner from passing through the communication port. Have. Thus, by providing the communication port provided with the filter 75 in the inlet space 70, it is possible to suppress an increase in internal pressure in the inlet space 70 and to prevent the toner from being ejected from the inlet portion 8.

  Further, even in the developing device 6 having a configuration in which the entrance space 70 is not formed, a communication port that communicates the space on the downstream side of the toner carrying roller 7 with respect to the toner carrying direction from the entrance portion 8 and the outside of the casing 61. A filter 75 that is a filter member for preventing toner from passing through the communication port may be provided. As described above, by providing the communication port including the filter 75 on the toner accommodating portion 66 side of the inlet portion 8, an increase in the internal pressure of the space from the inlet portion 8 to the toner accommodating portion 66 can be suppressed. The ejection of toner from the portion 8 can be prevented.

  Further, as described with reference to FIG. 9, the developing device 6 of the present embodiment has a casing outlet that is an end portion of the casing 61 that forms an end portion of the opening 90 on the upstream side of the toner carrying roller 7 in the toner conveyance direction. The exit width Wb and the entrance width Wa, which are the distance from the side end portion 61b to the surface of the toner carrying roller 7, satisfy the relationship of the entrance width Wa ≧ the exit width Wb. Accordingly, the cloud height H of the toner in the cloud state on the surface of the toner carrying roller 7 can be adjusted by the outlet portion 9 that is the outlet of the opening 90, and the toner in the cloud state can easily enter from the inlet portion 8, so that the toner scatters. Can be prevented.

  Further, the developing device 6 of the second and fourth embodiments includes a regulating member 63 on the upstream side of the toner carrying roller 7 in the toner carrying direction from the outlet 9, and the toner carrying of the toner carrying roller 7 from the outlet 9. An exit space 71 is formed on the upstream side in the direction and on the downstream side in the toner conveyance direction of the toner carrying roller 7 from the position where the regulating member 63 is provided. In the exit space 71, the width in the normal direction of the surface of the toner carrying roller 7 from the surface of the toner carrying roller 7 to the inner wall surface of the casing 61 is larger than the exit width Wb. By forming the outlet space 71 as described above, the toner that has passed through the regulating member 63 and dropped onto the inner wall surface of the casing 61 can be stored in the outlet space 71, and the toner that has dropped onto the inner wall surface of the casing 61 can be stored. It is possible to prevent leakage from the outlet portion 9 and toner scattering.

  Further, in the developing devices 6 of Examples 1 to 4 and 6, one end is fixed to each end of the inlet portion 8 and the outlet portion 9 of the casing 61, and the other end is a free end. An inlet seal 67 and an outlet seal 68 are provided. Then, the entrance seal 67 and the exit seal 68 are formed of a conductive material and are electrically installed on the ground, so that the entrance seal 67 and the exit seal 68 are not charged, so that toner adhesion is suppressed. Accordingly, it is possible to prevent the occurrence of toner scattering due to the toner drop that accumulates and falls as the toner adhering to each seal accumulates.

  Further, by applying a bias having the same polarity as the charging potential of the toner to the inlet seal 67 and the outlet seal 68, each seal and the toner are electrically repelled, so that the adhesion of the toner is suppressed and the toner adhering to the seal accumulates. Thus, it is possible to prevent occurrence of toner scattering due to falling toner falling.

  Further, at least the charging device 2 and the photosensitive belt 11 among the photosensitive belt 11 that is a latent image carrier that carries a latent image or the charging device 2 that is a charging unit that uniformly charges the surface of the photosensitive belt 11. In the process unit 60 in which the developing means for developing the carried latent image is held by a common holding body and is detachable from the printer 100 main body as an image forming apparatus as one unit, the developing device 6 is used as the developing means. Is used. Thereby, it is possible to improve the operability at the time of replacement of the developing device 6 that can more reliably prevent toner scattering.

  Further, in the printer 100 that is an image forming apparatus that includes the photosensitive belt 11 that is a latent image carrier that carries a latent image and the developing unit that develops the latent image on the photosensitive belt 11, the developing device 6 serves as the developing unit. By using toner, it is possible to prevent toner scattering, thereby preventing the occurrence of image defects in which dirt inside the apparatus or scattered toner adheres to the image, and good image formation can be performed.

1 is a schematic configuration diagram illustrating a printer according to an embodiment. FIG. 2 is a schematic configuration diagram showing the printer while a process unit is being attached and detached. Explanatory drawing of the process unit in a printer. FIG. 3 is a perspective view showing a toner carrying roller of a process unit. FIG. 3 is a schematic plan view showing an electrode configuration of a toner carrying roller. FIG. 3 is an enlarged cross-sectional view showing a toner carrying roller. FIG. 4 is a waveform diagram showing characteristics of a pulse voltage applied to an electrode of a toner carrying roller. FIG. 9 is a schematic diagram illustrating a modified example of a toner carrying roller. Explanatory drawing of the developing device provided with the characteristic part in an opening part. FIG. 3 is an explanatory diagram of a developing device according to Embodiment 1. FIG. 6 is an explanatory diagram of a developing device according to Embodiment 2. FIG. 6 is an explanatory diagram of a developing device according to Embodiment 3. FIG. 6 is an explanatory diagram of a developing device according to Embodiment 4. FIG. 10 is an explanatory diagram of a process unit according to the fifth embodiment. FIG. 10 is an explanatory diagram of a developing device according to a fifth embodiment. FIG. 10 is an explanatory diagram of a developing device according to Embodiment 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Belt unit 2 Charging device 3 Fixing device 3a Pressure roller 3b Fixing roller 4 Optical writing unit 6 Developing device 7 Toner carrying roller 8 Inlet portion 9 Outlet portion 10 Developing counter roller 11 Photosensitive belt 11a Secondary transfer backup roller 11b Drive Roller 11c Tension roller 12 Secondary transfer roller 20a A phase electrode 20b B phase electrode 21a A phase common electrode 21b B phase common electrode 22 Surface layer 23 Support substrate 24 Power supply 25 Flange member 50 Paper feed cassette 51 Paper feed roller 52 Paper feed path 53 Registration roller pair 60 Process unit 61 Casing 61a Casing inlet side end 61b Casing outlet side end 62 Supply roller 63 Regulating member 64 Paddle 65 Sheet member 66 Toner accommodating portion 67 Inlet seal 68 Outlet seal 69 Toner seal 7 Inlet space 71 outlet space 75 filter 76 electrode member 90 opening 100 printer

Claims (17)

A toner carrier having a plurality of electrodes arranged in a predetermined direction;
Toner supply means for supplying toner to the endlessly moving surface of the toner carrier;
Forming a toner containing portion for containing toner to be supplied to the toner carrying member, and having a developing casing provided with the toner carrying member and the toner supply means inside;
The toner carrier is opposed to the latent image carrier at an opening formed in a part of the developing casing;
While the toner carried on the surface of the toner carrying body is hopped on the surface by an electric field formed by applying a voltage to the plurality of electrodes to form a cloud state, the toner carrying body and the latent image carrying Transport to a developing position that is opposite to the body, and develop the latent image by attaching toner to the latent image carried on the latent image carrier at the developing position;
In the developing device for transporting the toner that has passed through the developing position without adhering to the latent image carrier into the developing casing in a cloud state,
An inlet width Wa that is a distance from the end of the developing casing to the surface of the toner carrier that forms an inlet that is an end of the toner carrier downstream of the toner carrier in the toner conveyance direction; Cloud height H, which is the height of the toner in the cloud state at
Wa ≧ H
Satisfy the relationship
A toner reverse flow preventing means for preventing toner from moving from the inside of the developing casing toward the inlet portion on the downstream side of the toner carrying member in the toner transport direction from the inlet portion. apparatus. The developing device according to claim 1.
As the toner backflow prevention means, the carrier is disposed so that the surface thereof faces the surface of the toner carrier and the distance between the surface of the toner carrier and the toner carrier is closer to the downstream side in the toner transport direction. A developing device comprising an opposing member. The developing device according to claim 1 or 2,
As the toner backflow prevention means, an inlet internal seal member that contacts the toner carrier and seals the inner wall surface of the developing casing and the surface of the toner carrier is provided.
The contact pressure of the seal member with respect to the toner carrier is such that the toner particles contacting the surface of the toner carrier can pass through the portion where the seal member contacts with the endlessly moving surface of the toner carrier, and the backflow of the toner. A developing device characterized in that the contact pressure is a level that can prevent The developing device according to claim 3.
A toner regulating member that regulates the toner layer on the toner carrying member on the upstream side in the toner carrying direction of the toner carrying member from an outlet that is an upstream end of the toner carrying member in the toner carrying member on the opening. Have
The inlet inner seal member abuts on the surface of the toner carrier with an inlet inner seal abutment pressure Fa, and the toner regulating member abuts on the surface of the toner carrier with a regulating member abutment pressure Fb. The internal seal contact pressure Fa and the regulating member contact pressure Fb are:
Fa ≦ Fb
A developing device satisfying the relationship: The developing device according to claim 2.
The normal line of the surface of the toner carrier on the downstream side of the toner carrier in the toner conveyance direction from the inlet and on the upstream side of the toner carrier in the toner conveyance direction from the position where the carrier-opposing member is disposed. A developing device characterized in that an inlet space portion having a width in the direction wider than the inlet width Wa is formed. The developing device according to claim 3 or 4,
The normal line of the surface of the toner carrier on the downstream side of the toner carrier in the toner conveyance direction from the inlet and on the upstream side of the toner carrier in the toner conveyance direction from the position where the inlet internal seal member is disposed. A developing device characterized in that an inlet space portion having a width in the direction wider than the inlet width Wa is formed. The developing device according to claim 1, 2, 3 or 4,
As the toner backflow prevention means,
An inlet space portion having a width in the normal direction of the surface of the toner carrier wider than the inlet width Wa is formed downstream of the inlet portion in the toner conveyance direction of the toner carrier. Development device. The developing device according to claim 5, 6 or 7,
A developing device comprising an electrode member to which a bias having a polarity opposite to a charging potential of toner is applied in the entrance space. The developing device according to claim 1, 2, 3 or 4,
As the toner backflow prevention means,
A developing device comprising an electrode member to which a bias having a polarity opposite to a charging potential of toner is applied, on the downstream side of the toner carrying member in the toner transport direction from the inlet portion. The developing device according to claim 1, 2, 3, 4, 5, 6, 7, 8, or 9.
As the toner backflow prevention means,
A communication port that communicates the space downstream of the toner carrying member with respect to the toner carrying direction from the inlet and the outside of the developing casing; and a filter member that prevents toner from passing through the communication port. A developing device. The developing device according to claim 5, 6, 7 or 8,
As the toner backflow prevention means,
A developing device comprising: a communication port that communicates the inlet space with the outside of the developing casing; and a filter member that prevents toner from passing through the communication port. The developing device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 10 or 11.
The exit width Wb, which is the distance from the end of the developing casing that forms the upstream end of the toner carrier in the toner conveying direction of the opening to the surface of the toner carrier, and the inlet width Wa,
Wa ≧ Wb
A developing device satisfying the relationship: The developing device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12.
A toner regulating member that regulates the toner layer on the toner carrying member on the upstream side in the toner carrying direction of the toner carrying member from an outlet that is an upstream end of the toner carrying member in the toner carrying member on the opening. Have
In the normal direction of the surface of the toner carrier, on the upstream side of the toner carrier in the toner conveyance direction from the outlet and on the downstream side of the toner carrier in the toner conveyance direction from the position where the toner regulating member is provided. A developing device, characterized in that an outlet space is formed having a width wider than an outlet width Wb, which is a distance from the end of the developing casing to the surface of the toner carrier at the outlet. The developing device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13.
An end of the developing casing at an inlet portion which is an end portion on the downstream side in the toner conveyance direction of the toner carrier at the opening portion and an outlet portion which is an end portion on the upstream side of the toner carrier in the toner conveyance direction of the opening portion. One end is fixed to the part, the other end is a free end, and includes an inlet seal and an outlet seal close to the surface of the latent image carrier,
The developing device characterized in that the inlet seal and the outlet seal are conductors. The developing device according to claim 14, wherein
A developing device, wherein a bias having the same polarity as a charging potential of toner is applied to the inlet seal and the outlet seal. At least one of a latent image carrier that carries a latent image, a charging unit that uniformly charges the surface of the latent image carrier, and a cleaning unit that cleans the surface of the latent image carrier, and the latent image carrier In a process unit in which a developing unit that develops a latent image carried on a body is held by a common holding body and can be attached to and detached from the image forming apparatus main body as one unit.
A process unit using the developing device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 as the developing means. In an image forming apparatus having a latent image carrier that carries a latent image, and a developing unit that develops the latent image on the latent image carrier.
An image forming apparatus using the developing device of claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 as the developing means. .

Images