JPH07281527A - Non-magnetic one-component developing device - Google Patents

Abstract

(57) [Summary] [Object] To enable stable formation of a thin toner layer in a non-magnetic single-component developing device while maintaining a reduction in driving torque and downsizing of the device. A developing device 24 includes a developing roll 33 that carries and conveys toner while being in contact with the photosensitive drum 21 to develop an electrostatic latent image on the photosensitive drum 21, and a supply roll that supplies toner to the developing roll 33. 34, a doctor blade 35 which is pressed against the developing roll 33 and forms a thin toner layer on the developing roll 33. The developing roll 33 is formed by surrounding a core metal 33a with a rubber member 33b having a rubber hardness of 40 degrees or more and a wall thickness of 3 mm or more. Doctor blade 35
Adheres the thin metal plate 35b to the elastic member 35a and is supported by the supporting member 36, and the spring 37 (37 ', 3
7 "), the surface of the flat surface of the metal thin plate 35b is pressed against the developing roller 33. The surface of the flat surface of the metal thin plate 35b is roughened, and its ten-point average roughness Rz is 1.
It is within the range of 10 μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-magnetic one-component developing device incorporated in an image forming apparatus such as a printer, a copying machine or a facsimile machine which employs an electrophotographic system. The present invention relates to a contact-type non-magnetic one-component developing device that develops by bringing a developing roll having a thin layer of non-magnetic one-component developer into contact with an image carrier (photoconductor).

[0002]

2. Description of the Related Art FIGS. 10 (a), 10 (b) and 10 (c) are schematic views of a conventional contact type non-magnetic one-component developing device, each of which uses a doctor blade having a different structure. As shown in these figures, the contact type non-magnetic one-component developing device generally carries a non-magnetic one-component toner and conveys it to develop an electrostatic latent image on a photosensitive drum D as an image carrier. A supply roll 2 as a supply means for supplying the non-magnetic one-component toner to the developing roll 1; a doctor blade 3 (4, which is pressed against the developing roll 1 to form a thin layer of the non-magnetic one-component toner on the developing roll 1; 5) and the like. Normally, the developing roll 1 is an elastic roll such as a rubber roll, and the elastic roll is held in pressure contact with the photosensitive drum D. The developing roll 1 has, for example, a rubber hardness of 3 in order to obtain a uniform developing nip to obtain a high-quality image and to reduce the driving torque to prevent unstable development.
A relatively low hardness of 0 to 40 degrees or less was used.

Further, in order to carry a uniform thin toner layer on the developing roll 1 and obtain stable development, the developing roll 1
The mutual configuration of each member such as the supply roll 2 and the doctor blade 3 (4,5) is extremely important, and various proposals have been made. For example, even a single doctor blade is known as shown in FIGS. 10 (a) to 10 (c). Here, the doctor blade 3 shown in FIG. 10 (a) is a rubber blade, which is supported by a holder 6 so as to be pressed against the developing roll 1 by its elastic force, and shown in FIG. 10 (b). The doctor blade 4 is a metal blade, and the developing blade 1 is made of elastic metal.
It is configured to be supported by the holder 7 so as to be pressed against. Also,
The doctor blade 5 shown in FIG. 10 (c) is a flat rubber blade, which is supported by a holder 8 as a supporting member, and the flat surface of the blade 5 is supported by a spring 9 as a spring member. It is a planar pressure contact type configured so as to be in pressure contact with, and is superior in size and cost reduction compared to the doctor blades 3 and 4 described above.

In any case, such a doctor blade has its own elasticity (in the case of FIGS. 10 (a) and 10 (b)).
Alternatively, it is pressed against the developing roll 1 by an auxiliary means such as a spring (in the case of FIG. 10C). The doctor blade 5 shown in FIG. 10C will be described in more detail. As shown in FIG. 11, a plurality of springs 9 and 9'for urging the blade 5 made of a rubber blade to press the developing roll 1 into pressure contact. ,
9 ″ is arranged along the longitudinal direction of the holder 8, and these springs 9, 9 ′ and 9 ″ are attached to the blade 5 via the holder 8.
Is pressed against the developing roll 1, and conventionally, the holder 8 is generally evenly weighted by the plurality of springs 9, 9 ′ and 9 ″. It is made of a rigid metal such as an aluminum sash, etc. Since the non-magnetic one-component toner is mainly triboelectrically charged when passing between the blade 5 and the developing roll 1, the blade 5 has a considerably large pressure. Is usually pressed against the developing roll 1. In addition, from the viewpoint of durability of the blade 5 and the like, a thin metal plate may be interposed on the pressing surface side of the blade 5 with the developing roll 1 (see FIG. 2). Proposed.

[0005]

In the conventional doctor blade 5 shown in FIG. 11, in general, in order to overcome the strong toner carrying force and form a thin toner layer on the surface of the developing roll 1, the blade 5 itself. The elastic force of must be strengthened. However, if the elastic force of the blade 5 itself is increased, the surface pressure at the pressure contact portion between the blade 5 and the developing roll 1 becomes non-uniform, and a phenomenon called so-called waviness occurs,
Thin layer unevenness occurs.

In order to prevent such thin layer unevenness,
Although the pressure contact force is increased by the auxiliary members such as 9, 9 ', 9 "as shown in FIG. 11, in this case, the rotational torque of the developing roll 1 becomes large, so that a strong driving force is required. It also leads to unstable development.

Further, in the prior art, the springs 9, 9 ',
As shown in FIG. 12, the developing roll 1 (especially one having a reduced diameter) is deformed so as to bend due to the load of 9 ″, etc., and the contact pressure at the central portion is lower than that at the both end portions. There is also a problem that the toner thin layer is not sufficiently formed in some part.
There is no choice but to thicken the core metal to prevent the above bending as much as possible. However, by doing this, the developing roll 1
Not only will the weight of the machine become heavier and the weight of the entire machine also heavier, but if the same roll diameter is attempted to be maintained, the thickness of the rubber part will decrease due to the thicker core metal and the cushioning property will increase. Since the pressure decreases, vibration cannot be absorbed at the pressure contact portion with the photoconductor drum D, and blurring occurs, which is extremely undesirable.

Further, in the case where the blade 5 is in direct contact with the surface of the developing roll 1 as shown in FIG. 10 (c) and FIG. 11, the blade 5 is, for example, as shown in FIG. It gradually wears from the initial use state shown in a), and finally reaches the end of use state shown in FIG. 13B and reaches the end of its life. Therefore, in order to extend the life of the blade 5, it is necessary to increase the rubber thickness of the blade 5. However, if the blade 5 is thickened in this way, the advantages of the compact size and low cost, which are unique to the planar pressure welding type blade, are diminished. In addition,
This also applies to a doctor blade of the type shown in FIG. 10 (a). Therefore, if only wear is considered, a metal blade may be used as shown in FIG. 10 (b), but even if a metal thin plate is interposed on the side of the blade 5 that is in pressure contact with the developing roll 1,
The above-mentioned problems that occur in forming a uniform and stable thin toner layer cannot be solved.

On the other hand, if the pressure contact force of the blade 5 is too weak or uneven, the toner T enters the gap between the blade 5 and the developing roller 1 as shown in FIG. However, there is a problem that other excess toner in the arrow B direction enters the arrow C direction and lifts the blade 5. This will be described in more detail below.

First, from the initial use state shown in FIG. 13A, the developing roll 1 and the blade 5 are rubbed together with the toner, and the blade 5 is gradually worn. In this way, the abrasion of the blade 5 progresses, and when the edge portion 5a of the blade 5 comes into contact with the developing roller 1 as shown in FIG. 13B, the toner on the developing roller 1 has the edge portion 5a.
Completely blocks and does not form a thin toner layer sufficient for development. Therefore, the life of the blade 5 is reached until the state of FIG. 13B is reached. In order to extend the life of the blade 5, it is conceivable to make the rubber hardness of the blade 5 hard. However, in this case, the surface of the developing roll 1 is easily worn and the surface condition is changed, so that a thin toner layer is formed. However, this is not the preferred means. Therefore, as shown in FIG. 13C, by increasing the distance L from the contact point of the blade 5 with the developing roll 1 to the edge portion (of course, the thickness of the blade 5 is increased correspondingly), the blade 5
It is an effective means to extend the life of the device (of course, the advantages of small size and low cost as mentioned above are diminished).

However, by increasing the distance L, the gap formed by the blade 5 and the developing roll 1 in the initial state of use becomes wider. Here, as shown in FIG. 13C, the developing roll 1 and the supplying roll 2 are rotating in the directions of arrows A and B, which are opposite to each other at their abutting portions, and the toner involved in the development is developed. Roll 1
Although the toner advances from the supply roll 2 to the blade 5 on the surface, the toners located near the developing roll 1 and the supplying roll 2 are also affected by the movements of the supplying roll 1 and the developing roll 2, and the toner from the supplying roll 2 to the developing roll 1 Move in the direction of.
A part of the toner moves upward without entering the gap between the blade 5 and the developing roll 1 as shown by the arrow A, but the toner in a portion relatively close to the developing roll 1 has the above gap as shown by the arrow B. Head to. Such a toner flow causes a force that opposes the force of the spring 9 pressing the blade 5 against the developing roller 1, that is, a force of lifting the blade 5.

Then, as the distance L is increased in order to extend the life of the blade 5, the gap created by the blade 5 and the developing roll 1 becomes wider, and the amount of toner entering the gap also increases. Since the force for lifting the blade 5 is also large, the thinning of the toner layer by the blade 5 is weak and unstable. Therefore, it has been difficult to extend the life of the blade 5 and to stabilize the thin toner layer.

On the other hand, as described above, when the developing roll 1 having a relatively low hardness of 30 to 40 degrees or less is used, a uniform developing nip can be obtained and the driving torque can be reduced. However, the following problems occur. That is, the material of the developing roller 1 having such a low hardness is NBR, urethane rubber, chloroprene rubber, silicone rubber, etc., which have SP values (compatibility index) with the photoconductor binder resin or toner resin. However, when left in contact for a long period of time, the plasticizer and unreacted low molecular weight components in the developing roll 1 exude and dissolve the toner and the binder resin for the photoconductor because the developing roll is chemically unstable. There were inconveniences such as being lost.
Therefore, in order to eliminate such inconvenience, a means of coating the surface of the developing roll 1 with acrylic, nylon, or the like, or winding a metal seamless belt is taken, but this results in high cost. There was a problem. It was also used to select a toner resin or photoconductor binder resin that has a relatively low compatibility with the material of the developing roll, but with this, only a limited part of the material can be used, and there is no freedom in design. There was a problem that the degree was narrow.

By the way, when the developing device having the structure shown in FIG. 13 (a) is assembled and driven, the contact force between the blade 5 and the developing roll 1 is such that no toner is present at the pressure contact portion. Is very large, and moreover, since the blade 5 is constantly pressed by the spring 9, the driving torque required for the developing roll 1 when it is driven for the first time from a new state becomes very large. Therefore, unless the structure of the drive system is designed with sufficient strength,
A situation such as a gear jump or damage to a drive transmission system component such as a gear may occur, causing a serious failure such as image blurring or a failure of a new developing device. Even if a drive system of a sturdy material and structure is designed to avoid such a situation, the developing roller 1 starts to rotate once and a thin toner layer is formed between the blade 5 and the developing roller 1. If it is done, the driving torque required thereafter is drastically reduced, resulting in an excessive design only for the first rotation, which is not preferable in terms of cost.

As described above, the conventional non-magnetic one-component developing device has various problems to be solved. In view of the above problems, the present invention provides a non-magnetic one-component developing device capable of forming a stable toner thin layer and obtaining a stable image while maintaining a reduction in driving torque and a reduction in size of the device. The purpose is to provide.

[0016]

In order to achieve the above object, the present invention provides a developing roll for carrying and conveying a non-magnetic one-component developer to develop an electrostatic latent image on an image carrier, and a developing roll. A non-magnetic device comprising: a supply unit that supplies the non-magnetic one-component developer; and a doctor blade that presses a flat portion against the developing roll to form a thin layer of the non-magnetic one-component developer on the developing roll. In the one-component developing device, the ten-point average roughness Rz of the surface of the flat surface of the doctor blade is 1 to 10 μm.
It is characterized by

[0017]

As a result of examining the relationship between the ten-point average roughness Rz of the doctor blade surface and the developer transport amount on the surface of the developing roll after passing the blade, the developer transport amount decreases as Rz increases ( That is, the regulation force of the developer is increasing), the developer transport amount is almost saturated at Rz = 1 μm or more, and when Rz is further increased, Rz = 10 μm.
As described above, it was first revealed by the inventor of the present invention that the image began to get rough. From this, Rz is 1
It can be seen that by setting the thickness in the range of 10 μm, the regulation force of the developer can be enhanced and a stable thin layer can be formed even with weak pressure contact.

As described above, according to the present invention, the thinning ability, which was conventionally performed by the elastic force, is enhanced by utilizing the surface roughness of the blade, and the thinning ability of the developer is increased. A sufficiently stable thin layer can be obtained even with spring loading.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a non-magnetic one-component developing device according to an embodiment of the present invention, FIG. 2 is a detailed view of a doctor blade and its supporting structure in the embodiment, and FIG. 3 is a developing device of the embodiment. FIG. 1 is an overall view of an image forming apparatus (herein, a printer device is shown as an example) having a built-in printer.

The image forming apparatus shown in FIG.
A paper feed cassette 11 for stacking and storing sheets, a paper feed roll 12 for sequentially feeding the stacked sheets, an image forming unit 13 for forming a toner image on the fed sheets based on image information, and the toner image on the sheet. A fixing device 14 for fixing the sheet, a sheet discharge roll 15 for discharging the sheet after fixing to the outside of the apparatus, a sheet discharge tray 16 for storing the discharged sheet, and the like. Also,
The image forming unit 13 includes a photoconductor drum 21 as an image carrier that continuously rotates in a fixed direction, a charger 22 that uniformly charges the surface of the photoconductor drum 21, and image information on the charged surface of the photoconductor drum 21. Of the optical writing head 23, which forms an electrostatic latent image by exposure to light based on the above, and the electrostatic latent image on the surface of the photoconductor drum 21 is developed with a non-magnetic one-component toner to obtain a toner image. Magnetic one-component developing device 2
4, a transfer device 25 for transferring the toner image onto the conveyed paper, a cleaner 26 for collecting and removing the untransferred toner remaining on the photosensitive drum 21, and the like.

The developing device 24 is, as shown in detail in FIG. 1, a toner storage tank 31 for storing a non-magnetic one-component toner T, a stirring member 32 for stirring the toner T in the toner storage tank 31, and a photoconductor. A developing roll 33 that carries and conveys the toner T while being in contact with the drum 21 to develop the electrostatic latent image on the photosensitive drum 21, a supply roll 34 as a supply unit that supplies the toner T to the developing roll 33, and a developing roll. 33
It is provided with a doctor blade 35 and the like which is pressed against the developing roller 33 to form a thin layer of the toner T on the developing roller 33. Hereinafter, the main members (especially the developing roll 33, the supply roll 34, and the doctor blade 35) constituting the developing device 24 of this embodiment will be described in more detail.

As shown in FIG. 1, the developing roll 33 is a rubber roll having a diameter of, for example, about 18 mm. For example, a core metal 33a having a diameter of about 12 mm is covered with a thick rubber member 33b having a thickness of about 3 mm. It consists of
The rubber member 33b is made of a harder polyether-based urethane rubber or the like having a rubber hardness of 40 degrees or more, and its surface has a polymerizing reaction enhanced by, for example, isocyanate treatment, and the resistance value of the rubber member 33b is For example, 1 × 10
It is about ⁶ Ωm. The reason why the rubber hardness of the rubber member 33b is set to be relatively hard and the thickness thereof is set to be thick will be described later. The photosensitive drum 21 has a diameter of, for example, about 30 mm, and the developing roller 33 has a radius of, for example, 7/1 with respect to the photosensitive drum 21.
It is pressed with a biting amount (roll crush amount) of about 0.63 mm, which is 00 times, and its contact width is, for example, about 1 mm.

The supply roll 34 is made of, for example, urethane sponge having a diameter of about 14 mm and about 80 cells / inch and containing carbon so as to have conductivity. The supply roll 34 is pressed against the developing roll 33, and the nip width thereof is, for example, about 2.86 mm.

The doctor blade 35 is, for example, as shown in FIG. 2, a flat elastic member 35a made of, for example, an elastic rubber (CR rubber) sheet having a thickness of about 1 mm, and a stainless plate having a thickness of about 0.185 mm. It has a multi-layered structure in which a thin metal plate 35b made of, for example, is adhered with a double-sided adhesive tape or the like, and its length in the longitudinal direction (the central axis direction of the developing roller 33) is, for example, about 210 mm, and in the lateral direction (the horizontal direction in FIG. 2). ) Is, for example, about 4 to 5 mm. As shown in FIG. 4, this doctor blade 35 is adhered to and supported by a supporting member 36 such as an aluminum sash over the longitudinal direction, and the whole thereof is at a plurality of points in the longitudinal direction (for example, three points at the center and both ends in FIG. 4). The flat portion of the thin metal plate 35b is pressed against the developing roll 33 with a predetermined pressure by being urged toward the developing roll 33 by the spring 37 (37 ', 37 ") as a spring member disposed in the. The contact width is, for example, about 1 mm Note that the metal thin plate 35b is electrically connected to the support member 36 by a claw (not shown) at the end thereof.

Here, the surface of the flat surface of the metal thin plate 35b, which is the pressure contact surface with the developing roll 33, is roughened, and the ten-point average roughness Rz of the surface is 1 to 10 μm (more preferably 3 to 7 μm). It is set within the range. Here, the "ten-point average roughness Rz" is one of the surface roughness evaluation methods specified in JIS, and is the average line of the portion extracted by the reference length from the cross-sectional curve of the target surface. Of the straight lines parallel to, select the line that passes through the third peak from the highest and the line that passes through the third valley from the deep and select this 2
Measure the distance between the straight lines of the book in the direction of the vertical magnification of the section curve,
The value is expressed in units of μm. Ten-point average roughness R
The reason why z is set in the range of 1 to 10 μm will be described later.

In FIG. 4, the spring pressure of the spring 37 'disposed at the center is set to be about 30% stronger than the spring pressure of the springs 37, 37 "disposed at both ends. Further, the support member 36 is, as shown in FIG.
Multiple locations in the longitudinal direction (springs 37, 37 ', 3 in FIG. 4)
A slit 38 cut in a direction intersecting with the longitudinal direction is provided in (between the weighting points by 7 ″) so that the bending of the developing roller 33 can be followed.

Further, as shown in FIGS. 5 and 6, a flexible sheet member 39 is provided at a toner entrance portion formed by the flat surface portion of the doctor blade 35 and the peripheral surface of the developing roller 33, and the supply roller 34. The amount of toner entering the toner entrance portion can be adjusted to an appropriate amount by regulating the flow of toner from the inside. That is, the sheet member 39 is the blade 35
And the supply roll 34 are arranged along the longitudinal direction of the developing roll 33, and the surface near one end of the developing roll 33 has the developing roll 3
3, and the other end is fixed to a part of the casing of the developing device. As such a sheet member 39, for example, a urethane sheet having a thickness of about 0.1 mm to 0.5 mm can be used, but the sheet member 39 is flexible so as not to be chemically or physically affected by the toner or the developing roll 33. As long as the material has good properties, various other materials can be adopted. The operation of the seat member 39 will be described later in detail.

The photosensitive drum 21 and the developing roll 3
3, the rotation speed of the supply roll 34 is, for example, 35.5
4 mm / sec, 45.7 mm / sec, 47.4 mm / sec
It is set to a degree. Furthermore, the charging potential of the photosensitive drum 21 and the exposure portion potential are, for example, −650 V and −80, respectively.
Is set to about -100V, and the developing roll 33,
The bias potentials applied to the supply roll 34 and the doctor blade 35 are, for example, -250V, -500V,
It is set to about -500V. As the non-magnetic one-component toner T, for example, one having an average particle diameter of about 10 μm and made of polyester resin or the like and having a toner charge amount of about 6 to 8 μc / g is used.

In the above construction, the doctor blade 3
The reason for setting the ten-point average roughness Rz of the surface of the flat surface of 5 (surface of the thin metal plate 35b) to 1 to 10 μm will be described in detail below.

First, the relationship between the surface roughness (ten-point average roughness Rz) of the thin metal plate 35b and the toner transport amount on the surface of the developing roll 33 after the thin toner layer was examined, and the relationship as shown in FIG. 7 was found. Was obtained. According to the figure, when the ten-point average roughness Rz on the surface of the metal thin plate 35b is increased, the amount of toner conveyed decreases, that is, the toner regulation force increases, and Rz =
It can be seen that the amount of conveyed toner is almost saturated at 1.0 μm or more. On the other hand, if the ten-point average roughness Rz is further increased, R
It was also clarified that the image started to become rough at z = 10 μm or more and so-called streak became noticeable. From these facts, it is in the range of Rz = 1 [mu] m to 10 [mu] m that the toner has high regulation power and does not have an adverse effect on the image, and Rz =
It has been found that the range of 3 μm to 7 μm is more preferable. Therefore, the greatest feature of the present invention is that the ten-point average roughness Rz of the surface of the blade 35 is limited to this range. By doing so, the toner thinning, which has been conventionally performed by the elastic force, is enhanced by utilizing the surface roughness of the blade 35, and the toner thinning ability is sufficiently increased by the amount corresponding to that amount. A thin layer can be obtained.
For example, conventionally, the pressing force applied to the blade was 150 g / cm to 200 g / cm per unit length in the longitudinal direction, whereas when the surface roughness was roughened as described above, 100 g / cm to 120 g / cm. Even with the setting of cm, it is possible to obtain a sufficient toner thin layer.

Next, the grounds for setting the rubber hardness of the rubber member 33b of the developing roller 33 to be relatively hard and the thickness thereof to be relatively thick will be described in detail below. First, as a developing roll, in the case of forming a urethane rubber roll by reacting a polyether polyol and an isocyanate as in the conventional case, the relation between the ratio of the low molecular weight component and the rubber hardness was examined, and the result is shown in FIG. A relationship like this was obtained. According to the figure, when the degree of reaction is advanced,
It can be seen that the unreacted low molecular weight component decreases as the hardness increases. Then, developing rolls having different hardness were prepared by changing reaction conditions variously, a thin toner layer was formed on these developing rolls, and a storage test was conducted for 20 days at a temperature of 50 ° C. and a humidity of 85%. Got the result. As is clear from Table 1, the toner using the styrene-acrylic resin has no problem of sticking at a rubber hardness of 35 degrees or more, and the toner using a polyester resin has a problem of sticking at a rubber hardness of 45 degrees or more. There was no

[0032]

[Table 1]

Then, a general non-magnetic one-component developing device was constructed by using the developing roller of high hardness which does not have the problem of sticking, and the image was confirmed. Only unsatisfactory images were obtained. The reason for the large amount of jitter is that the developing roll having high rubber hardness is pressed against the photosensitive drum, so that the driving torque of the developing roll becomes large, and the unevenness of rotation of the developing roll with respect to the load fluctuation is affected. Do you get it. Further, it was found that the large amount of blurring was due to the developing roll physically scraping the toner developed on the photosensitive drum because the rotation speed of the developing roll was slightly faster than that of the photosensitive drum.

Therefore, the inventor of the present invention has conducted various studies and carried out a method of relaxing the contact condition between the photosensitive drum and the developing roll by increasing the rubber thickness in proportion to the increased rubber hardness. . That is, the outer diameter of the developing roll is 18
When the image thickness is formed by using these developing rolls, the relationship between the maximum allowable crushing amount of the developing rolls and the hardness of the developing rolls is determined by changing the rubber thickness by changing the diameter of the core metal while keeping the mm constant. Upon examination, the results shown in FIG. 9 were obtained. As is clear from FIG. 9,
Rubber thickness 3 mm (core metal diameter 12 mm, developing roll diameter 18 m
In the case of m), when the rubber hardness is 45 degrees, there is no problem in the image when the developing roll and the photosensitive drum are in contact with each other at a crushing amount of zero, and the rubber thickness is 5 mm (core metal diameter 8 mm,
With a developing roll diameter of 18 mm, a good image can be obtained up to a crushing amount of 0.07 mm at a rubber hardness of 45 degrees, and a rubber thickness of 6 mm (core bar diameter of 6 mm, developing roll diameter of 18 m).
In the case of m), the crushing amount is 0.1 mm when the rubber hardness is 45 degrees.
It can be seen that a good image can be obtained up to. The crush amount of the developing roll is a calculated value obtained from the center distance between both the outer diameter of the photosensitive drum and the outer diameter of the developing roll. From these facts, the rubber hardness of the rubber member 33b of the developing roll 33 is set to 40 degrees or more (preferably 45 degrees or more) according to the JIS standard, and the rubber thickness of the rubber member 33b is increased to 3 mm or more by that amount. What has been done is an additional feature.

Therefore, according to this embodiment, as described above, the ten-point average roughness Rz of the surface of the flat surface of the doctor blade 35 (the surface of the thin metal plate 35b) is set to 1 to 10 μm. Since the toner thinning ability can be enhanced by utilizing this effect, and the spring load can be correspondingly reduced to suppress the pressure contact force of the blade 35 to the developing roll 33, the rotational torque of the developing roll 35 can be reduced. Therefore, the drive system of the developing roll 35 can be simplified and the cost can be reduced. In this embodiment, the thin metal plate 35b is used.
Although the surface of the is roughened, the gist of the present invention is to roughen the surface of the flat surface of the doctor blade, and the same can be applied to a conventional rubber blade that does not use the metal thin plate 35b. Of course. Of course, it can be said that the blade using the metal thin plate 35b is more preferable because the problem of wear over time (see FIG. 13) is almost eliminated.

Further, by setting the rubber hardness of the rubber member 33b of the developing roll 33 to a hardness of 40 degrees or more as described above, the conventional soft hardness (30 to 40 degrees).
Since no special treatment such as surface coating, which is required to eliminate the chemical instability of the developing roll, is required, a more inexpensive developing device can be realized. Moreover, by setting the rubber thickness of the rubber member 33b to a thickness of 3 mm or more as much as the rubber hardness of the rubber member 33b is made harder, it is possible to obtain a good quality and stable image even with a high hardness developing roll. Becomes

Further, in FIG. 4, since the spring pressure of the central spring 37 'is set to be stronger than that of the springs 37, 37 "at both ends, the flexure as shown in FIG. Even if occurs, since the largest spring load is applied to the blade 35 at the central portion where the deflection amount is the largest, the pressure contact force of the blade 35 to the developing roll 33 becomes uniform in the longitudinal direction, so that the toner thin layer is formed. It is possible to effectively prevent non-uniformity and obtain a high-quality image, and, in addition to this, the supporting member 3 for the blade 35.
Since the slit 38 is provided in 6 to follow the flexure of the developing roll 33, the blade 35 is also easily deformed according to the deformation of the developing roll 33, so that the pressing force of the blade 35 against the developing roll 33 is always maintained. It is possible to make the image more uniform in the longitudinal direction, and it becomes possible to form a higher quality image.

Further, as shown in FIGS. 5 and 6, a flexible sheet member 39 is provided at a toner entrance portion formed by the flat surface portion of the blade 35 and the peripheral surface of the developing roller 33, and the toner entrance portion is provided. Since the toner inflow amount is adjusted to an appropriate amount, the following actions and effects can be obtained. That is, as shown in FIG. 13C, the sheet member 39 blocks the flow of toner in the direction of arrow C, which gives a force to lift the blade 5 from the surface of the developing roll 1, and the flow of toner is illustrated. As shown by arrow D in 6, it works to release upward. As a result, the blade 35 moves to the developing roll 3
3, it is possible to obtain a uniform and stable toner thin layer because the constant position can be maintained at all times, and the blade 35
It can also contribute to prolonging the life of the. In this case,
The toner supplied from the supply roll 34 onto the developing roll 33 is relatively strongly attached to the developing roll 33 due to the supply bias and the elasticity of the supplying roll 34, so the toner on the developing roll 33 is removed by the sheet member 39. You don't have to worry about it being done. However, if the thickness of the sheet member 39 is increased to 2 mm or more, or if the material thereof is hard, the flexibility of the sheet member 39 is impaired, and toner is removed from the developing roll 33 on the developing roller 33 like the regulating blade. Since it will be scraped off, which is not preferable, it is necessary to make it sufficiently flexible. Also, the sheet member 39
Since the same effect can be obtained if at least the portion abutting the developing roller 33 is flexible, the portion fixed to the casing may be a separate member such as metal or plastic.

A part of the toner reaching the toner entrance portion passes through the blade 35 and is used for development, but the remaining toner does not pass through the blade 35 and is transferred to the blade 35.
It is possible that it may stay in the vicinity. Therefore, FIG.
As shown by a two-dot chain line therein, the sheet member 39 is provided with an opening 39a along the longitudinal direction of the developing roll 35, and excess toner entering the vicinity of the toner entry portion is passed through the opening 39a as indicated by an arrow E. It is also effective to let it escape to the outside of the toner entrance portion.

By the way, the developing device of this embodiment shown in FIG. 1 has a unit structure which is detachable from the main body of the image forming apparatus shown in FIG. It is desirable to do like this. That is, when assembling various components for the developing device,
Toner may be attached in advance to the contact surface between the blade 35 and the developing roll 33, for example, the surface of the blade 35 (the surface of the thin metal plate 35b) or the surface of the developing roll 33 that is in contact therewith, and the toner may be assembled in this state. To do. With this configuration, even when the new developing device assembled as described above is incorporated into the image forming apparatus and driven for the first time, the contact surface between the blade 35 and the developing roll 33 is changed as described above. Toner has already been attached to the
The adhesion between the blade 35 and the developing roll 33 is weak, and therefore the driving torque required for the developing roll 33 at the start of driving does not become large as in the conventional case, and smooth driving is possible. Therefore, even if the drive system is not made to have a sturdy structure, it is possible to avoid the conventional problems such as gear jump and damage to the drive transmission system components.

In the above, various characteristic points included in one embodiment of the present invention (points of roughening the surface of the flat surface of the blade 35, blade 35 of elastic member 35a and thin metal plate 35b) are used.
And a multi-layered structure, the hardness of the developing roll 33 is made harder and the wall thickness is thicker, the spring pressure of the central spring 37 'is made stronger, and the support member 36 can follow the bending of the developing roll 33. The point that the sheet member 39 is provided in the toner entrance portion, and the point that the toner is adhered to the contact surface between the blade 35 and the developing roller 33 in advance are described. In addition, if the devices are combined with each other, a synergistic effect can be obtained. And, it is possible to provide a highly reliable low torque non-magnetic one-component developing device as described above.

In the above embodiment, specific numerical examples are given for each member, but these numerical examples are preferable examples and the present invention is not limited to these numerical values.

[0043]

According to the present invention, the surface of the flat surface of the doctor blade is roughened (Rz = 1 to 10 μm), and the thinning ability of the developer can be enhanced by utilizing the surface roughness. As a result, since the pressing force of the doctor blade to the developing roll can be suppressed to a low level, it is possible to reduce the rotating torque of the developing roll. Therefore, the developing roll drive system can be simplified and the cost can be reduced. It is possible to realize a highly reliable developing device that can be realized.

Furthermore, if the doctor blade has a multi-layer structure of an elastic member and a metal thin plate and the surface of the metal thin plate is pressed against the developing roll, the problem of wear over time without increasing the size of the blade will occur. It can also be resolved.

If the hardness of the developing roll is set to be relatively high and the thickness of the developing roll is set to be thicker by that amount,
It is possible to realize a developing device that is chemically stable for a long period of time and can obtain a high-quality image even if the developing roll is not subjected to any special treatment, at a lower cost.

When the strength of the spring member for pressing the doctor blade is increased at the center of the blade longitudinal direction, the pressing force of the doctor blade to the developing roll becomes uniform in the longitudinal direction even if the developing roll bends. Therefore, it is possible to prevent the thin layer of the developer from becoming non-uniform and obtain a good quality image. Even if the supporting member of the doctor blade can follow the bending of the developing roll, the same effect can be obtained, and a more preferable effect can be obtained by combining these.

If a sheet member is provided at the developer entrance portion so that the developer entrance amount is adjusted to an appropriate amount, there is no concern that unnecessary pressure will be applied to the doctor blade due to an inappropriate flow of the developer. In addition, a stable developer thin layer can be obtained, and the life of the doctor blade can be extended.

If the developer is adhered to the contact surface between the doctor blade and the developing roll in advance, the adhesive force is weakened, so that the torque at the start of driving the developing roll can be reduced. Extremely smooth drive is possible without making the drive system a sturdy structure.

[Brief description of drawings]

FIG. 1 is a sectional view of a non-magnetic single-component developing device according to an embodiment of the present invention.

FIG. 2 is a detailed view of a doctor blade 35 and its support structure in the above-described embodiment.

FIG. 3 is an overall view of an image forming apparatus including the developing device according to the embodiment.

FIG. 4 is a view showing a countermeasure against the bending of the developing roller 33 in the above embodiment, and is a view seen from the right side in FIG.

FIG. 5 is a perspective view showing an arrangement example of a sheet member 39 in the above-mentioned embodiment.

FIG. 6 is a cross-sectional view showing an arrangement example of the sheet member 39.

FIG. 7: Surface roughness of doctor blade (10-point average roughness R
FIG. 6 is a diagram showing a relationship between z) and the toner conveyance amount on the surface of the developing roll after the thin toner layer.

FIG. 8 is a diagram showing a relationship between a ratio of a low molecular weight component and rubber hardness when a developing roll of a urethane rubber roll is molded.

FIG. 9 is a diagram showing the relationship between the maximum allowable crushing amount of a developing roll and the hardness of the developing roll when an image is formed by using the developing rolls having a constant developing roller outer diameter and different rubber thicknesses. is there.

FIG. 10 is a schematic view of a conventional contact type non-magnetic one-component developing device, in which (a) uses a rubber blade, (b) uses a metal blade, and (c) shows a planar pressure contact type. The one using a blade is shown.

11 is an exploded perspective view of the developing device shown in FIG.

FIG. 12 is a diagram showing a problem of bending of the conventional developing roll 1.

13A and 13B are views showing a problem of wear of the blade 5 in the related art, where FIG. 13A shows an initial state of use, FIG. 13B shows an end state of use, and FIG. Shows the state of the toner entering.

[Explanation of symbols]

 21 Photoreceptor Drum 24 Non-Magnetic One-Component Developing Device 31 Toner Storage Tank 32 Stirring Member 33 Developing Roll 33a Core Bar 33b Rubber Member 34 Supply Roll 35 Doctor Blade 35a Elastic Member 35b Metal Thin Plate 36 Supporting Member 37, 37 ', 37 "Spring 38 Slit 39 Sheet Member 39a Opening

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Abe 2-229 Sakuragaoka, Higashiyamato, Tokyo Casio Electronics Co., Ltd. (72) Inventor Shigeki Okawa 2-229 Sakuragaoka, Higashiyamato, Tokyo Casio Electronics Co., Ltd. Incorporated (72) Inventor Mitsugu Oishi 2-229 Sakuragaoka, Higashiyamato-shi, Tokyo Casio Electronics Co., Ltd.

Claims (10)

[Claims] 1. A developing roll for carrying and carrying a non-magnetic one-component developer to develop an electrostatic latent image on an image carrier; a supply means for supplying the non-magnetic one-component developer to the developing roll; A non-magnetic one-component developing device comprising: a doctor blade which presses a flat portion against a developing roll to form a thin layer of the non-magnetic one-component developer on the developing roll; Point average roughness Rz
Is 1 to 10 μm. A non-magnetic one-component developing device. 2. The non-magnetic one-component developing device according to claim 1, wherein the ten-point average roughness Rz is 3 to 7 μm. 3. The doctor blade has a multi-layer structure in which an elastic member is brought into pressure contact with the developing roll via a thin metal plate, and the pressure contact surface of the thin metal plate with the developing roll is the surface of the flat portion. The non-magnetic one-component developing device described. 4. The non-magnetic single component according to claim 1, wherein the developing roll is a rubber roll having a cored bar in the center, the rubber hardness of the rubber roll is 40 degrees or more, and the wall thickness of the rubber roll is 3 mm or more. Development device. 5. A plurality of spring members for urging the flat portion of the doctor blade against the developing roll are arranged in the longitudinal direction of the doctor blade, and the longitudinal direction of the plurality of spring members is the longitudinal direction. The non-magnetic one-component developing device according to claim 1, wherein the biasing force of the spring member arranged at the center is set to be stronger than that of the spring members arranged at both ends in the longitudinal direction. 6. The non-magnetic single-component developing device according to claim 1, further comprising a supporting member that supports the doctor blade in a longitudinal direction thereof, the supporting member having a structure capable of following the bending of the developing roll. 7. The non-magnetic one-component developing device according to claim 6, wherein the support member has slits cut at a plurality of positions in the longitudinal direction in a direction intersecting with the longitudinal direction. 8. A sheet member for adjusting a proper amount of developer entering the developer entrance portion is provided at a developer entrance portion formed by the flat surface portion of the doctor blade and the peripheral surface of the developing roll. The non-magnetic one-component developing device described. 9. The non-magnetic one-component developing device according to claim 8, wherein the sheet member has an opening that allows excess developer that has entered near the developer entry portion to escape to the outside of the developer entry portion. 10. The non-magnetic one-component developing device according to claim 1, wherein a developer is previously attached to the contact surface between the doctor blade and the developing roll prior to the first use of the device.