JPH09114234A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device constituted so that pressing force for pressing a developer regulation member to a developer carrier side is easily and accurately imparted and the part of the developer regulation member abut ting on the circumferential surface of the developer carrier is easily and accu rately positioned. SOLUTION: This image forming device is provided with the developer carrier 2 turned by carrying developer on the circumferential surface and set for carrying the developer to a developing position faced to an electrostatic latent image carrier 1 and the developer regulation member 3 abutting on a prescribed position of the circumferential surface of the carrier 2 and forming a developer layer whose thickness is previously decided. The abutting part of the regulation member 3 is positioned and fixed so as to abut on the fixed position of the carrier 2. On the other hand, the back surface of the abutting part of the regulation member 3 is provided with a pressure imparting member 4 pressing the regulation member 3 to the carrier 2 side and making the abutting part of the regulation member 3 abut on the fixed position of the carrier 2 by prescribed pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for an image forming apparatus such as an electrophotographic copying machine, a facsimile or a printer, and more particularly to a developing device using a one-component developer.

[0002]

2. Description of the Related Art Conventionally, as a developing device for developing an electrostatic latent image formed on an electrostatic latent image bearing member such as a photosensitive drum, a developing device using only a developer containing an image forming substance (toner) has been used. There is known a one-component developing device.

As shown in FIG. 12, a conventional one-component developing device has a hopper (developer supply chamber) 34 for accommodating a developer.
And a developer carrying member (developing roll) 32 which is arranged to face the electrostatic latent image carrying member (photosensitive drum) 31 and has a built-in magnet roll, and a developer regulating member whose one end is in pressure contact with the developer carrying member. (Layer forming blade) 33, and an alternating voltage obtained by superimposing a DC voltage on an AC voltage is applied as a developing bias voltage to the developer carrying member.

In such a structure, the developer accommodated in the hopper is carried on the peripheral surface of the developer carrier by the magnetic force of the magnet roll, and the electrostatic latent image carrier is rotated as the developer carrier rotates. It is transported to the development area facing the. At this time, the developer is thinned to a predetermined thickness by the developer regulating member, and an electric charge is applied by frictional charging with the developer regulating member. As a result, when the alternating voltage is applied to the developer carrier and an alternating electric field is formed in the developing region where the electrostatic latent image carrier and the developer carrier face each other, a magnetic force is applied to the developer carrier. The carried developer receives an electrostatic attraction force corresponding to the electric charge, migrates in the developing area, and adheres to the image portion of the electrostatic latent image formed on the electrostatic latent image carrier to form the electrostatic latent image. To develop.

As described above, in the developing device, since the developer in the hopper is once carried on the surface of the developer carrying member and then supplied to the electrostatic latent image carrying member, it is formed on the surface of the developer carrying member. The state of the developer layer has a great influence on the image quality of the product copy. For example, if the thickness of the developer layer formed on the surface of the developer carrier is not uniform, the density of the image formed on the electrostatic latent image carrier may be uneven, resulting in uneven density on the final copy paper. Occurs. Also, when the charge is not uniformly applied, the density of the image formed on the electrostatic latent image carrier is uneven, and uneven density is generated on the copy paper, as described above.

In order to prevent the image quality deterioration due to the uneven density on the copy paper, the developer is carried on the surface of the developer carrier in a thin layer having a uniform thickness, and a uniform and sufficient charge is given. It must be. A developer regulating member is provided for performing these operations, and the developer carried on the surface of the developer carrying member is pressed against the surface of the developer carrying member by the pressing force of the developer carrying member to cause friction. Then, the developer is electrostatically charged, and the surface of the developer is smoothed by the contact portion of the developer regulating member, so that a thin developer layer having a uniform thickness is formed.

As described above, the developer regulating member performs two treatments on the developer carried on the surface of the developer carrying body, namely, providing electric charge and making the layer thickness uniform. Among them, the electric charge is evenly applied. In order to achieve this, a pressing force with a predetermined strength must be applied at all times, while on the other hand, the contact portion of the developer regulating member must be fixed at a predetermined position in order to make the layer thickness uniform.

However, as shown in FIG. 12, in the conventional developing device, the pressing force of the developer regulating member is such that the developer regulating member made of an elastic material such as a stainless steel blade is bent and attached to the developing device. Since the deformation reaction force obtained by was used, when installing the developer regulating member,
The developer regulating member has to be attached so as to have an accurate bending amount, and also the abutting portion has to be attached so as to be fixed at an accurate position. Therefore, meticulous attention and great effort are required to attach the developer regulating member so that the two precisions of the contact portion positioning precision and the pressing force precision are simultaneously satisfied. Further, since the strength of the pressing force may vary depending on how the developer regulating member is attached, defective products are likely to occur when the developer regulating member is attached during the assembly process of the developing device, and the defective rate of the product is high. It also had the drawback of being expensive.

Further, in the case of a developer regulating member for fixing a conventional blade made of an elastic material or the like in a bent state to a blade supporting portion provided in the main body of the developing device by bolting, a fixing portion on the blade. (Bolted part)
And the force for fixing the blade to the supporting part is different in the part where the bolt is not fastened between the fixed part and the fixed part, the strength of the pressing force to bring the contact part of the blade into contact with the developer carrier is weak. However, there is a problem in that the contact portion causes a “waviness phenomenon” in which the surface of the developer carrier is curved like a corrugated plate. When the blade contact portion curved in a corrugated plate is brought into contact with the developer carrying member, the developer layer formed by the blade contact portion also becomes a corrugated plate having a non-uniform thickness. When an electrostatic latent image is developed, transferred and fixed using a developer layer having a non-uniform thickness, image unevenness with streaky patterns on the copy paper surface occurs.

The "waviness phenomenon" is caused by increasing the amount of bending when attaching the elastic blade and increasing the force for pressing the blade against the developer carrying member. It is possible to suppress the portion located at the tip of the intervening portion from floating from the surface of the developer carrier, and therefore, in the developing device of high pressing force type, it does not cause much problem, but in the developing device of low pressing force type, Since the pressing force is weak and the pressing force is not enough to eliminate the "waviness phenomenon", it becomes a serious problem especially for a developing device of low pressing force type.

On the other hand, Japanese Patent Publication No. 67187/1988 discloses a developing device having means for removing the developer remaining on the surface of the developer carrying member after supplying the developer to the photosensitive drum in order to improve the copy image quality. However, in such an apparatus, the surface of the developer bearing member is almost "roughened" for the purpose of easily removing the developer remaining without being supplied to the electrostatic latent image bearing member. Since it is in a non-smooth state, the force for holding the developer is weak, and if the pressing force for pressing the developer on the surface of the developer carrier is increased, the thickness of the carried developer layer becomes too small. Therefore, the pressing force cannot be increased, and the device is inevitably a low pressing force type device.

Further, there is a strong demand for improvement in copy resolution, and in order to meet this demand, it is necessary to increase the thickness of the developer layer to improve the maximum color density, and from this point as well, the pressing force of the developer regulating member is increased. The need to keep it low is increasing. Therefore, as a trend of improvement of the developing device, there is a tendency toward a low pressing force type, and even at a low pressing force, the unevenness of the thickness of the developer layer due to the "waviness phenomenon" of the blade as described above does not occur. Therefore, there is a demand for development of a developing device in which electric charges are evenly applied by friction and which does not cause image unevenness.

As a method of eliminating the "waviness phenomenon" of the elastic blade, there has been proposed a method of fixing the developer regulating member with a uniform force using an adhesive or the like, instead of fixing the bolt. Certainly, according to this method, the above-mentioned "waviness phenomenon" does not occur, but with respect to the point that the developer regulating member must be attached so as to simultaneously satisfy the positioning of the contact portion and the accuracy of the pressing force, It does not solve the problem that the device has, and because the developer regulating member must be fixed in a bent state until the bonding is completed, workability is poor, and there is a positional shift before the completion of bonding and after bonding. There are also new problems such as the possibility that the adhesive surface may peel off.

In Japanese Patent Laid-Open No. 27577/1993, the position at which the elastic blade is mounted is determined by adopting a double-ended beam structure that supports the elastic blade at two positions spaced along the direction of rotation of the developer carrying member. A developing device has been proposed in which accuracy is improved and triboelectrified charges are applied so as to contact the surface of the developer bearing member at a portion between the two positions where the elastic blade is supported.

However, since the developing device has a structure in which the pressing force is applied by the bending repulsive force of the elastic blades supporting both ends, the pressing force cannot be specified at the stage before assembling the developing device, and the elastic blades cannot be specified. The pressing force may fluctuate depending on the mounting state of. Therefore, there is a problem that the required pressing force cannot be applied accurately.

Further, in the double-end supporting beam structure as disclosed in the above-mentioned Japanese Patent Laid-Open No. 5-27577, the portion of the elastic blade that abuts the developer carrying member is drawn by the rotation of the developer carrying member and deforms. However, there is also a problem that it is not possible to regulate the thickness of the developer layer on the developer carrier so that the thickness is uniform because the end of the contact portion of the elastic blade cannot be fixed at a predetermined position. .

Further, in such a developing device, the pressing force is determined by the length of the flexible portion of the elastic blade that does not come into contact with the developer carrier and the elastic coefficient, so that the rotation of the developer carrier is as described above. It is conceivable that the pressing force fluctuates due to the deformation of the flexible portion when it is drawn. Therefore, in order to obtain a stable pressing force in spite of such deformation, it is necessary to make the length of the bent portion a certain length or more. Therefore, a space for accommodating such an elastic blade having a certain length or longer is required in the developing device, which causes a problem that the downsizing of the developing device is hindered.

Further, in FIG. 4 of JP-A-5-27577, an endless annular elastic blade is used as the elastic blade 4, and the elastic blades 4 are arranged along the rotation direction of the annular elastic blade 4. It is disclosed that two portions are fixed and supported by a supporting member, and a part of the elastic blade 4 is brought into contact with the developing sleeve 3.

However, this elastic blade is no different from the conventional developing device in that the developer regulating member also has a pressing force imparting function, and the abutting end of the elastic blade 4 is placed at a predetermined position. Since it cannot be fixed, there is a problem that the thickness of the developer layer on the developer carrying member cannot be regulated so as to be uniform.

As described above, in the conventional one-beam supporting method, the function of bringing the developer regulating member (elastic blade) itself into contact with the developer carrying member depends on the developer regulating member. The developer regulating member must be attached so as to simultaneously satisfy the two precisions of the contact portion positioning precision and the pressing force precision, which requires great care and great effort.

In particular, in the low pressing force type developing device, there is no means for effectively preventing the deterioration of the image quality due to the "waviness phenomenon" of the developer regulating member, which has been a problem.

Further, in the prior art (Japanese Patent Application Laid-Open No. 5-27579) method of supporting two spaced apart places, it is not possible to accurately apply the pressing force and accurately position the contact portion due to its structure. It has drawbacks.

[0023]

Therefore, the inventors of the present invention have solved such conventional problems, and can accurately and easily apply a pressing force to a developer regulating member and position an abutting portion. As a result of intensive research on a developing device capable of forming a uniform thin developer layer and imparting a uniform and sufficient electric charge even under a low pressing force, the pressing force imparting function that has been entrusted to conventional developer regulating members has been achieved. By separating the two functions of the contact part positioning function and the contact part positioning function, the pressing force applying function is transferred to another member, and the developer regulating member has only the positioning function.
The present invention has been completed by finding that the application of pressing force and the positioning operation of the contact portion can be performed easily and with high accuracy.

Therefore, it is an object of the present invention to provide a developing device which can easily apply a pressing force and position an abutting portion with high accuracy.

Still another object of the present invention is to provide a developing device capable of easily and highly accurately applying a pressing force and positioning a contact portion even under a low pressing force.

[0026]

According to the present invention, there is provided a developing device for an image forming apparatus such as an electrophotographic copying machine, a facsimile, and a computer, which carries a developer on its peripheral surface and rotates. A developer carrier that conveys the developer to a developing position facing the adjacent electrostatic latent image carrier, and a developer having a predetermined layer thickness by abutting on a predetermined position on the peripheral surface of the developer carrier. In a developing device of an image forming apparatus having a developer regulating member forming a layer, the developer regulating member is positioned and fixed such that its abutting portion abuts at a fixed position with respect to the developer carrier. , A pressure applying member is provided on the back surface of the contact portion to press the developer bearing member side,
A developing device is provided in which the contact portion of the developer regulating member is in contact with a fixed position of the developer carrier at a predetermined pressure by the pressing force of the pressure applying member.

The developer carrying member carries the developer in the developer accommodating portion on the peripheral surface by magnetism or electrostatic attraction, and conveys it to a developing position facing the electrostatic latent image carrying member. There is a columnar one called "," or a belt-shaped one called a developing belt.

The developer regulating member is in contact with the peripheral surface of the developer carrying member to thin the developer carried on the peripheral surface of the developer carrying member to a predetermined thickness, and also to friction with the developer. By doing so, it is charged to give an electric charge.

The developer regulating member of the present invention has a function of positioning and fixing the abutting portion that abuts the developer carrying member with respect to the developer carrying member, but does not have a pressing force due to a deformation reaction force or the like. This is different from the conventional developer regulating member in this respect.

The developer regulating member of the present invention is attached in a state in which its abutting portion is positioned and fixed so as to abut on the developer carrier at a fixed position. Here, "positioned and fixed so as to abut at a fixed position" means that the abutting portion of the developer regulating member that abuts the developer carrier does not move in the direction of rotation of the peripheral surface of the developer carrier. It means that it is attached so as to always come into contact with the peripheral surface of the rotating developer carrier at a constant position.

In other words, in the direction in which the state in which the positioning and fixing are maintained so as to contact the peripheral surface at a fixed position, that is, the pressing force is applied, the contact portion may move. Well, for example, a state of a cantilever in which one end of the developer regulating member is fixed to the developing device main body, or one end of the straight plate-shaped developer regulating member is parallel to the axis of the developer carrying member The contact portion is movable about the axis in a direction substantially normal to the peripheral surface, or is positioned at one end of a straight plate-shaped developer regulating member in a direction perpendicular to the plane of the developer regulating member. The pin may be provided with a hole or a protrusion so that the abutting portion can be attached in a state of being movable in the direction of the substantially normal line of the peripheral surface.

The form of the developer regulating member is not particularly limited as long as it can position and fix the contact portion, and may be, for example, a straight plate shape, a curved plate shape, or a three-dimensional shape such as a rectangular parallelepiped.

The material of the developer regulating member is not particularly limited as long as it can position and fix the abutting portion, and may be an elastic body such as metal, resin or rubber. Further, although a conductive material or a non-conductive material may be used, when a conductive material is used, a voltage can be applied to it.

However, in the developer regulating member, the material of the abutting portion which comes into contact with the developer carrying member needs to be a material capable of imparting an electric charge to the developer by friction. For example, resin, rubber, etc. are also included.

Further, by making the shape of the abutting portion into a curved surface cut out by a cylinder having the same shape as the peripheral surface of the abutting developer bearing member, the area where the abutting portion contacts the developer bearing member is increased. Therefore, sufficient triboelectrification can be generated between the developer carried on the developer carrying member and the developer carried thereon.

The developer regulating member of the present invention has a main function of positioning and fixing the abutting portion, and is mounted in a state without a deformation reaction force such as bending, so that the abutting portion can be accurately positioned. And it can be done easily. Further, since the bending portion for giving the deformation reaction force is not necessary, the developer regulating member can be downsized, and the developing device as a whole can be downsized.

The pressure applying member is located on the rear surface of the developer regulating member contact portion in the developing device, and functions to press the developer regulating member toward the developer carrier to bring it into contact with a predetermined pressure. It is a member and is a characteristic member of the developing device of the present invention. In the developing device of the present invention, the pressing force for bringing the developer regulating member into contact with the developer carrying member is applied not by the developer regulating member but by a pressure applying member provided separately from the developer regulating member.

The pressure applying member is typically made of an elastic material and does not have a pressing force before being attached to the developing device. , Simply referred to as a “holding portion”), and when the developer regulating member and the developer carrying member are attached to predetermined positions of the developing device, force is applied to the pressure applying member to deform it.
The pressure applying member presses the developer regulating member toward the developer carrying member side by the deformation reaction force that tries to return to the original shape against this deformation.

The pressure applying member is on the back surface of the abutting portion of the developer regulating member in the developing device, and a part thereof is in contact with the back surface of the abutting portion of the developer regulating member. It is attached to a position where it can be pressed toward the carrier side. Typically, a holding portion is provided in the developing device at a predetermined distance from the back surface of the contact portion of the developer regulating member,
The developer regulating member is attached in the space formed between the rear surface of the contact portion and the holding portion.

Since the pressure applying member is held by being sandwiched between the developer regulating member and the holding portion, its position may be displaced after the attachment as in the case of using a typical hollow tubular pressure applying member. If it does not exist, it does not necessarily have to be fixed to the developing device main body, but it may be fixed because it may be displaced after attachment depending on the form of the pressure applying member. As a method of fixing, for example, adhesion, screwing, etc. can be considered, but in the case of a material such as a polymer material that can be easily molded, a convex portion is provided on a part of the pressure applying member and the developing device main body is provided. If it is fitted in the recess provided in the fixed holding portion, it can be fixed with good workability. Further, a recess having the same shape as the outer shape of the pressure applying member may be provided in the holding portion inside the developing device so that a part of the pressure applying member is accommodated therein.

The size of the pressure applying member is not particularly limited as long as it can be located on the back surface of the abutting portion of the developer regulating member in the developing device and can give a sufficient pressing force. Not done. Typically, the length of the pressure applying member in the direction of the rotation axis of the developer carrier is about the same as the length of the developer regulating member in the direction of the rotation axis of the developer carrier. The length of the developer carrying member in the rotating direction is approximately the same as the length of the developer carrying member in the rotating direction of the developer carrying member, so that the developer controlling member also functions as a seal for the end portion. It may be longer than the member.

The shape of the pressure applying member is not particularly limited as long as it can accurately apply a predetermined pressing force to the developer regulating member when attached to the developing device.
A typical example is a hollow tubular shape having a substantially circular cross-sectional shape as shown in FIG. Also, as a modification,
A pressure applying member and a developer regulating member are integrally formed, a leaf spring is deformed, a coil spring or a spiral leaf spring-like member is arranged along the contact portion, and a plurality of pressure applying members are provided. One that is stacked in the pressing direction, one that is formed by cutting out a part of the tubular member, one that is filled with a pressure applying medium such as liquid or gas, and a plurality of pressure applying members in the rotating direction of the developer carrier. Lined up, multiple pressure applying members lined up in the direction of the rotation axis of the developer carrier, pressing force at the center and both ends of the rotation axis by changing the wall thickness of the developer carrier in the direction of the rotation axis It is conceivable that the strength of the magnetic field is changed, or in the case of applying to the non-magnetic one-component system, the repulsive force of the magnet is used to apply pressure in the pressing direction.

The material of the pressure applying member is not particularly limited as long as it can accurately apply a predetermined pressing force to the developer regulating member in the state of being attached to the developing device.
Typically, an elastic material such as rubber, resin or steel can be used. Further, as the material of the pressure applying member, either a conductive material or a non-conductive material can be applied. However, when a conductive material is used, a bias voltage can be applied to the pressure applying member, so that a bias voltage is applied. By adjusting the voltage, it is possible to obtain the effect of controlling the amount of charge applied to the developer through the contact portion of the developer regulating member.

Next, the process of attaching the pressure applying member of the present invention and its effects will be described. When a pressure applying member made of a hollow tubular member having a typical substantially circular cross-sectional shape is attached to a holding portion provided on the back surface of the developer regulating member in the developing device, the holding portion, the developer regulating member, and the developer carrying member Although it is sandwiched between itself and the body, it deforms, and the deformation reaction force stored at this time is used as a pressing force.

At the stage before the developer regulating member and the developer carrying member are attached, no force is applied to the pressure applying member. However, since the space between the holding portion and the back surface of the developer regulating member is generally smaller than the size of the pressure applying member before the deformation, when the pressure applying member is mounted in this space, a part of the pressure applying member carries the developer more than the holding portion. It is in a state of protruding toward the body side. Next, the developer restricting member and the developer carrying member are attached in contact with the pressure applying member. At this time, the previously applied pressure applying member is in contact with the peripheral surface of the developer carrying member and the developer restricting member. Since the back surface of the portion pushes and deforms the holding portion, the pushing force in the direction of the developer carrying body, which is the direction of giving the pushing force, is stored as the deformation reaction force.

This pressing force is determined by the amount of deformation given when the pressure applying member is attached to the developing device. The amount of deformation is
It is determined by the difference between the shape of the pressure applying member before attachment to the developing device and the shape after attachment, and the shape of the pressure applying member before attachment can be determined at the stage of designing the pressure applying member. Further, the shape of the pressure applying member after attachment is determined by the mutual positional relationship between the holding portion in the developing device, the developer regulating member, and the developer carrying member and the respective shapes. After all, the pressing force is determined at the stage of designing the device. Therefore, the mounting state of each member when assembling the apparatus has almost nothing to do with the pressing force, and the pressing force fluctuates in the mounting state when mounting the developer regulating member, which has been a problem in the conventional developing device. Since the possibility of doing so can be made extremely small, it is possible to easily attach the developer regulating member, and it is possible to obtain the effect that the pressing force can be applied with high precision. Further, since the strength of the pressing force can be accurately selected from a wide range by appropriately selecting the shape, material, wall thickness, etc. of the pressure applying member, the structure for applying the pressing force using the pressure applying member of the present invention Is particularly effective when used in a low pressing force type developing device.

[0047]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the developing device of the present invention will be described in detail below with reference to the accompanying drawings. (First Embodiment) As shown in FIG. 1, a developing device according to a first embodiment of the present invention includes a developer carrying member 2 adjacent to an electrostatic latent image carrying member 1, a developer regulating member 3, and a pressure. The developing member main body 7 and the like are provided, and except for the developer regulating member 3 and the pressure applying member 4, the developing device is essentially the same as the conventional developing device. The toner stirring means 19 (agitator) or the like is used. It has the structure of the component developing device.

FIG. 2 shows an outline of a laser beam printer constructed by using the developing device of the present invention. In the figure, reference numeral 1 is a photosensitive drum as an electrostatic latent image carrier, reference numeral 5 is a charging roll for charging the photosensitive drum 1 to a predetermined bright potential, and arrow 6 is a laser beam scanner not shown. A laser beam that is irradiated from the photosensitive drum 1 to write an electrostatic latent image on the photosensitive drum 1, and a developing device 7 that develops the electrostatic latent image formed on the photosensitive drum 1 with toner (developer). Reference numeral 8 is a sheet supply tray that sends out the recording sheet 9 at a predetermined timing in synchronization with the writing timing of the electrostatic latent image on the photosensitive drum 1.
Reference numeral 10 is a transfer roll that electrostatically transfers the toner image developed on the photosensitive drum 1 to the recording sheet 9, and reference numeral 11 is provided with a cleaning blade 12 that contacts the surface of the photosensitive drum 1 after the transfer of the toner image. Cleaner, code 13
Is a fixing device for fixing the toner image transferred onto the recording sheet 9 onto the recording sheet 9.

In this laser beam printer, the photosensitive drum 1, the charging roll 5, the developing device 7 and the cleaner 11 constitute one cartridge unit,
When the printing is completed on the specified number of recording sheets, the cartridge unit is entirely replaced. Therefore, by replacing this cartridge unit, you can replace the deteriorated photosensitive drum, replenish toner,
The waste toner collected by the cleaner can be collected at once.

Under such a structure, a toner image corresponding to image information is formed on the photosensitive drum 1 through the charging process by the charging roll 5, the exposure process by the laser beam 6 and the developing process by the developing device 7. The toner image is transferred to the recording sheet 9 at the position where the photosensitive drum 1 and the transfer roll face each other. The recording sheet on which the toner image has been transferred is discharged to a sheet discharge tray (not shown) via a fixing device, while the photosensitive drum 1 after the transfer process is cleaned by the cleaning blade to remove residual toner, paper dust, and other adhering substances. Are removed.

FIG. 1 shows a concrete structure of the cartridge unit. In the figure, reference numeral 14 denotes a cleaner housing that holds the photosensitive drum 1 rotatably. The cleaning blade 12 is fixed to the cleaner housing 14, and the cleaning blade 12 removes the surface of the photosensitive drum 1 from the surface. Adhered substances such as collected waste toner and paper powder are accumulated inside the device. The charging roll 5 is also rotatably held in the cleaner housing 14, and the charging roll 5 is pressed against the photosensitive drum 1 by a spring 15. Therefore, when the photosensitive drum 1 rotates, the charging roll 5 also rotates following the rotation of the photosensitive drum 1.

Further, the developing device 7 is swingably connected to the cleaner housing 14 via a pin 16, and a spring 17 interposed between the cleaner housing 14 and the developing device 7 is provided. The developing device is biased in one direction. As a result, the developing roller 2 as the developer carrying member provided in the developing device 7 and the cleaner housing 14
The gap between the photosensitive drum 1 and the photosensitive drum 1 held at is always kept constant.

On the other hand, in the developing device, the developing roll 2 carrying a thin layer of toner on its peripheral surface and rotating, the toner supply chamber 18 for supplying toner to the developing roll 2, and the toner supply chamber A layer forming blade 3 as a developer regulating member that forms the toner adhering to the developing roll 2 from 18 into a thin layer having a predetermined thickness, and an agitator (which rotates in the toner supply chamber 18 and agitates the toner in the chamber). Toner stirring means) 19.

Here, a magnetic toner is used as the toner, and the toner is carried on the peripheral surface by the magnetic force generated by the developing roller 2. That is, the developing roll 2 has a built-in magnet roll (not shown), and the toner in the toner supply chamber 18 is attracted to the peripheral surface of the developing roll 2 by the magnetic force of the magnet roll.

Further, one end of the layer forming blade 3 is in contact with the developing roll 2 with a predetermined pressing force, and the other end is fixed to the mounting block 21, so that the toner attached to the developing roll 2 is rubbed by the magnetic force. The layer is thinned to a predetermined layer thickness while being charged. A synthetic resin tube 4 having a substantially cylindrical cross-section as a pressure applying member is attached in parallel to the developing roll 2 at a holding portion provided at a position on the back surface side of the layer forming blade 3 of the attachment block 21. The tube 4 makes the layer forming blade 3 uniformly abut against the developing roll 2 from the back side with a predetermined pressing force.

The pressure-applying member used in the present embodiment is a substantially cylindrical tube made of synthetic resin, and goes from the rear surface of the developing roll and the layer-forming blade to the holding portion of the mounting block 21 when it is mounted on the developing device. The cross section is deformed into an elliptical shape by receiving the pressure in the direction, and the layer forming blade 3 is pressed toward the developing roll 2 side by the deformation reaction force against this deformation. A protrusion is provided on a part of the outer periphery of the pressure applying member, and the pressure applying member is attached to a predetermined position by fitting the protrusion into a concave recess provided in the holding portion of the mounting block 21.

By adopting such a construction, the layer forming blade 3 can be attached at its end by the attachment block 21.
It can be easily performed by simply fixing the contact portion to the contact portion, and positioning and fixing of the contact portion can be performed easily and with high accuracy.
Further, since the pressing force is applied by the pressure applying member (tube) 4, the pressing force can be applied with high accuracy, and a developer layer having a uniform thickness can be formed on the peripheral surface of the developing roll 2. At the same time, sufficient charge can be uniformly applied.

(Second Embodiment) In the developing device of this embodiment, the pressure applying member and the developer regulating member are integrally formed in a shape in which the pressure applying member and the developer regulating member are combined as shown in FIG. The developing device has the same structure as the developing device of the first embodiment except that a molded product is used. In the case of using the integrally formed pressure applying member and the developer regulating member of the present embodiment, the mounting block 21 provided in the developing device main body
There is an advantage that the attachment of the developer regulating member and the pressure applying member is completed only by attaching the layer forming blade 3 to.

(Third Embodiment) In the developing device of this embodiment, as a pressure applying member, a leaf spring deformed by a press or the like so as to have a "C" -shaped cross section as shown in FIG. 4 is used. The developing device has the same structure as the developing device of the first embodiment except that it is used. Further, as shown in FIG. 5, a plurality of coil springs and spiral leaf springs (bamboo springs) are arranged along the abutting portion of the developer regulating member instead of the “C” -shaped leaf spring. You may use as an application member.

(Fourth Embodiment) In the developing device of this embodiment, two hollow tubular members each having a substantially circular cross section as shown in FIG. 6 are stacked as a pressure applying member in the direction in which a pressing force is applied. The developing device has the same structure as the developing device of the first embodiment except that the developing device integrally formed is used.
When the pressure applying member of this embodiment is used, the same advantage as that shown in the first embodiment is obtained by simply attaching the layer forming blade 3 to the attachment block 21 provided in the developing device main body. Besides, there is an advantage that a stable pressing force can be applied with high accuracy even when a weak pressing force is required.

(Fifth Embodiment) In the developing device of the present embodiment, a part of a shape in which two hollow tubular members each having a substantially circular cross section shown in FIG. The developing device has the same structure as that of the developing device of the first embodiment except that the developing device cut along a plane parallel to the rotation axis of the body is used. The pressure applying member of the present embodiment is effective when it is necessary to avoid applying a pressing force of a predetermined pressure or more.

(Sixth Embodiment) In the developing device of the present embodiment, as a pressure applying member, a pressure applying medium is provided inside a hollow tubular member having a substantially circular cross section made of a contractible elastic material shown in FIG. The developing device has the same structure as that of the developing device of the first embodiment except that a gas or a liquid sealed therein is used. This pressure applying member has an advantage that the pressing force can be adjusted to an arbitrary pressure value by adjusting the amount of gas or liquid sealed inside. Further, in this pressure applying member, since the pressing force is constantly and uniformly applied to the abutting portion by the gas or the liquid enclosed therein, there is an advantage that it is hardly affected by the environment such as room temperature or the temperature inside the apparatus.

(Seventh Embodiment) In the developing device of the present embodiment, the pressure applying member is different from the pressure applying member shown in FIG. 9 except that two magnets are arranged so that the same poles face each other. The developing device has the same structure as the developing device of the one embodiment. This pressure applying member has an advantage that the pressing force can be adjusted to a desired pressure value by appropriately selecting the magnetic forces of the facing magnets. Further, in this pressure applying member, since the pressing force does not depend on the elasticity of the material itself, there is no fear that the elastic material will be permanently deformed in a pressurized state and the contact force will be reduced. There are advantages that it is not easily affected by the environment such as humidity and that space for accommodating the elastic material that gives the deformation reaction force is not required, so that space can be saved.

(Eighth Embodiment) In the developing device of this embodiment, as the pressure applying member, two hollow tubular members are provided on the back surface of the developer regulating member shown in FIG. 10 in the rotating direction of the developer carrying member. The developing device has the same structure as that of the developing device of the first embodiment except that the developing device is used. When the pressure applying member of the present embodiment is used, it is possible to increase the area of the abutting portion of the developer regulating member even with a weak pressing force, and sufficient frictional charging with the developer may occur. There is an advantage that you can.

(Ninth Embodiment) In the developing device of this embodiment, a plurality of hollow tubular members each having a substantially circular cross section shown in FIG. 11 are arranged as a pressure applying member in the contact portion. The developing device has the same structure as that of the developing device of the first embodiment except that is used. When the pressure applying member of the present embodiment is used, there is an advantage that the pressing force can be distributed and applied. Further, by varying the wall thickness of each hollow tubular member, or by arranging tubular members having different diameters, it is possible to increase or decrease the pressing force applied in the rotational axis direction of the developer carrying member. This is effective when it is necessary to make a difference in the pressing force to be applied between the central portion and both end portions as a means for correcting the developing characteristics of the developer carrier such as the strength of the magnetic force in the rotation axis direction. . The same effect can be obtained when a single continuous hollow tubular member having different thicknesses or diameters at both ends and the center is used as the pressure applying member.

[0066]

According to the present invention, it is possible to provide a developing device in which the pressing force can be applied and the contact portion can be positioned easily and with high accuracy. Further, according to the present invention, it is possible to provide a developing device capable of easily and highly accurately applying a pressing force and positioning the contact portion even under a low pressing force.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a cartridge unit in which a developing device of the present invention is incorporated.

FIG. 2 is a schematic view showing a laser beam printer in which the developing device of the present invention is used.

FIG. 3 is a schematic view showing what is integrally molded in a shape in which a pressure applying member and a developer regulating member used in the developing device of the present invention are combined.

FIG. 4 is a schematic view showing a deformed leaf spring as a pressure applying member used in the developing device of the present invention.

FIG. 5 is a schematic view showing a member using a coil spring as a pressure applying member used in the developing device of the present invention.

FIG. 6 is a schematic view showing a pressure applying member used in the developing device of the present invention in which two hollow tubular members are stacked.

FIG. 7 is a schematic diagram showing a pressure applying member used in the developing device of the present invention, in which a hollow tubular member is partially cut.

FIG. 8 is a schematic view showing a pressure-applying member used in the developing device of the present invention in which a pressure-applying medium is enclosed in a hollow tubular member.

FIG. 9 is a schematic view showing a pressure applying member used in the developing device of the present invention in which two magnets are arranged such that the same poles face each other.

FIG. 10 is a schematic view showing a pressure applying member used in the developing device of the present invention in which two hollow tubular members are arranged in the rotational direction of the developer carrying member.

FIG. 11 is a schematic diagram showing a pressure applying member used in the developing device of the present invention in which a plurality of hollow tubular members are arranged and arranged in the direction of the rotation axis of the developer carrier.

FIG. 12 is a schematic diagram showing a configuration of a conventional developing device.

[Explanation of symbols]

1 ... Photosensitive drum (electrostatic latent image carrier), 2 ... Development roll (developer carrier), 3 ... Developer regulating member, 4 ... Pressure applying member.

Claims (5)

[Claims] 1. A developer carrier that carries a developer on a peripheral surface and rotates to convey the developer to a developing position facing an adjacent electrostatic latent image carrier, and a periphery of the developer carrier. In a developing device of an image forming apparatus having a developer regulating member that comes into contact with a predetermined position of a surface to form a developer layer having a predetermined layer thickness, the developer regulating member has a contact portion with a developer. It is positioned and fixed so as to come into contact with the carrier at a fixed position, and a pressure applying member that presses toward the developer carrier side is provided on the back surface of the abutting portion. The developing device is characterized in that the contact portion of the developer regulating member is in contact with a fixed position of the developer carrier with a predetermined pressure. 2. The image forming apparatus according to claim 1, wherein the pressure applying member is a hollow tubular member made of an elastic material and having a substantially circular cross section. 3. The image forming apparatus according to claim 1, wherein the pressure applying member is a member that applies an abutting force by a deformation reaction force. 4. The image forming apparatus according to claim 1, wherein the pressure applying member is fixed to the developing device main body. 5. The image forming apparatus according to claim 1, wherein the pressure applying member is integrally formed with the developer regulating member.