JP3383502B2 - One-component non-magnetic toner developing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a developing device for visualizing a latent image, and more particularly, to a developing device for visualizing a one-component non-magnetic toner layer formed on a developing roller. The present invention relates to a developing device that performs development by contacting and supplying an image. [0002] In an electrophotographic apparatus or an electrostatic recording apparatus,
In a developing means for contacting and supplying a thin layer of non-magnetic toner formed on the developing roller with a latent image formed on the latent image holding member and developing (visualizing) the latent image, a developing roller surface It is important to always carry and form a constant amount of toner layer. In other words, compared to a method in which magnetic toner is carried on the surface of the developing roller by magnetic action to perform development, non-magnetic toner cannot reliably exert a remote action such as a magnetic force, so It is difficult to always carry a fixed amount of toner. Here, a constant amount of toner is always carried on the developing roller surface,
The inability to contact and supply the latent image on the latent image holding member means that it is difficult to quickly supply and recover the required toner when the toner layer on the surface of the developing roller is consumed by the development of the latent image. In other words, the toner roller quickly recovers the toner layer on the surface of the developing roller, and shows a poor ability (toner transportability) to always supply a constant amount of the toner thin layer to the latent image. The quality of the transportability affects the quality of the developed toner image. Conventionally, in order to solve such a problem, the developing device is configured such that the toner is sequentially conveyed and supplied (consumed) by its own weight, but as a result, it may cause toner fogging. There are many. [0004] The toner fogging is as follows.
Not only does it adversely affect the developed image quality, but it also increases toner consumption and leads to higher running costs.
Avoidance and improvement measures from the structural aspect of the developing device are demanded. In view of this, a method of arranging the toner supply roller below the developing roller to prevent uncharged or weakly charged toner from being conveyed and supplied only by the influence of gravity can be considered. Means taking into account the positional relationship between the two rollers is effective as a method for reducing toner fogging, but conversely has the problem that toner transportability tends to deteriorate. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has a feature that a predetermined amount of toner can be adhered to a developing roller to maintain a constant image density at all times, and that a high quality image with less toner fogging can be obtained. It is an object of the present invention to provide a developing device capable of obtaining an image. According to a first aspect of the present invention, there is provided a developing roller disposed to face a latent image holding member, and a toner supplied to the developing roller disposed to face the developing roller. And a toner layer forming member for forming the toner supplied by the toner supply roller in a thin layer on a developing roller, and the latent image of the latent image holding member is formed by the thinned toner. In the one-component non-magnetic toner developing device for developing, the upper end of the toner supply roller is positioned lower than the upper end of the development roller, the toner supply roller and the development roller rotate in the same direction, and the toner layer forming member and the development roller When the contact point with the toner supply roller and the contact point between the toner supply roller and the developing roller is b, the arc ab is 1/8 to 1/3 of the circumference of the developing roller, and And direction is a component non-magnetic toner developing apparatus is characterized in that is disposed a toner supply assisting member. The toner supply roller must play the role of assisting the frictional charging of the toner and at the same time transporting the toner onto the developing roller, and therefore needs to rotate in the same direction as the developing roller. Further, in order to prevent the occurrence of toner fogging due to the toner being conveyed and supplied only by the influence of gravity, it is necessary to position the upper end of the toner supply roller below the upper end of the developing roller. However, if the point of contact with the toner layer forming member on the developing roller is too close to the point of contact with the supply roller, the toner flow generated between the developing roller and the toner supply roller may not be able to circulate neatly. . Further, since the contact area between the toner and the surface of the developing roller in the developing device is reduced, charging failure is likely to occur. Conversely, if the point of contact with the toner layer forming member on the developing roller is too far from the point of contact with the toner supply roller, the toner flow generated between the developing roller and the toner supply roller causes the toner layer to flow. Since the toner circulates at a position distant from the forming member, it becomes difficult for the charged toner to be efficiently conveyed. Therefore, when the contact point between the toner layer forming member and the developing roller is a and the contact point between the developing roller and the toner supply roller is b, the arc ab is 1/8 to 1/8 of the circumferential length of the developing roller.
It is necessary to satisfy 1/3. Further, even if the above setting is made, if the image output is continued for a long period of time, the toner is deteriorated due to the burying and falling off of the external additive (inorganic powder such as silica), and the charging ability is reduced. Therefore, the toner conveyance amount is easily reduced. As described above, even when the charging ability of the toner is reduced, in order to secure a required transport function without reducing the toner transport amount,
It is necessary to take measures to make the flow of toner in the vicinity of the toner supply roller smooth and active. Therefore, by arranging the toner supply auxiliary member on the toner supply roller facing (or in contact with or close to) the toner flow, the toner flow is changed, and the toner in a good charged state in which the toner is smoothly circulated in the vicinity of the toner supply roller. It is very effective to supply the developing roller. A one-component non-magnetic toner according to claim 1 of the present invention.
In the developing device, in addition to the features described above, the toner supply auxiliary member disposed to face the toner supply roller has a surface resistance of 10 ¹² Ω / □ or less and a bias is applied.
It is characterized by having. [0011] Toner which is excessively charged on the toner supply roller and causes electrostatic aggregation is difficult to be developed, so that streak-like toner is likely to be stuck, which may cause clogging of the toner supply roller. Also. In view of this, an excessively charged electric charge from the electrostatically aggregated toner is transferred to the toner supply auxiliary member by disposing a conductive toner supply auxiliary member facing (or in contact with or close to) the toner supply roller. In this case, electrostatic aggregation is alleviated, and the toner can be successively developed with a toner adjusted to an appropriate charge amount, so that a cycle of newly charging and developing the toner becomes smooth. As a result, it is possible to obtain a high-density image without fogging over a long period without causing toner sticking or clogging of the toner supply roller. It has been found that in order to obtain such an operation and effect, the surface resistance of the toner supply auxiliary member needs to be 10 ¹² Ω / port or less. The measurement of the surface resistance was 10
^{When 6} Ω / port or higher, Mitsubishi Yuka Co., Ltd. Hiresta, 10
^In the case of ⁶ Ω / port or less, the test was performed using the company's Loresta AP. When the toner supply assisting member is conductive, a bias can be applied to the toner supply roller in any of a toner supply direction and a toner removal direction. That is, it means that the bias condition can be optimized according to the characteristics of the toner. It can be applied up to a potential difference of ± 800 V with respect to the toner supply roller, preferably ± 200 V.
When used in the range of V, the effect on image quality is small. [0013] In the developing apparatus of the claim 1 Symbol placement is
It is preferable to adopt the following configuration. First, it is preferable that the toner supply auxiliary member is made of metal. That is, when the toner supply assisting member is made of metal, it has been found that the above-described effect of providing a charge and suppressing electrostatic aggregation are further enhanced. Further, the toner supply roller is JIS-K6401,
In the case of a foamable flexible foam having a hardness of 80 kgf or less, the surface area of the toner supply roller surface increases,
This is advantageous for frictional charging and transport of toner. However, if the hardness is too hard, it leads to an increase in driving torque. Therefore, JIS-K6401 is preferably 80 kgf or less. Still further, at a position where the toner supply auxiliary member and the toner supply roller are in contact with or closest to each other, the shape of the toner supply auxiliary member is a part or a plane of an arc having a curvature radius of 1 mm or more. That is, the radius of curvature
Not only when a sharp portion of less than 1 mm comes into contact, but also when it comes close, the toner flow on the toner supply roller or near the toner supply roller is disturbed more than necessary, and the toner on the toner supply roller or near the toner supply roller is removed. It works in the direction of peeling. Such a toner stripping function not only leads to an increase in driving torque, but also may deteriorate toner transportability. Therefore, it is desirable that the shape of the toner supply auxiliary member at the position where the toner supply auxiliary member contacts the toner supply roller or at the closest position is a part or a plane of an arc having a curvature radius of 1 mm or more. The one-component non-magnetic toner development of the invention according to claim 1
In addition to the above-described features, the apparatus further includes a contact depth 1 between the toner supply assisting member and the toner supply roller, which is −0.1.
It is characterized by a 5 mm ≦ l ≦ 0.5 mm
You . Here, when the contact depth is negative, it indicates the closest distance between the toner supply auxiliary member and the toner supply roller when they are not in contact with each other. Further, when the contact depth is positive, it refers to a form in which the two contact each other in such a way that they bite into each other.The difference between the radius of the toner supply roller and the distance from the center of the toner supply roller to the point of contact between the two means the contact depth. I do. In the above definition, if -0.5 mm <l, the toner supply auxiliary member and the toner supply roller are too far apart, so that the toner flow rotating around the outer periphery of the toner supply roller is applied to the toner supply auxiliary member. Since contact cannot be made, the effect of changing the toner flow, the effect of charging, and the effect of reducing electrostatic aggregation are reduced. Conversely, when 0.5 mm> l, the toner supply auxiliary member and the toner supply roller are in strong contact with each other, so that an increase in driving torque is inevitable, and an overload is applied to the toner. It may be hastened. Therefore, the contact depth 1 between the toner supply auxiliary member and the toner supply roller is desirably −0.5 mm ≦ l ≦ 0.5 mm, and more preferably −0.2 mm ≦ l ≦ 0.2 mm.
Is good. An embodiment will be described below with reference to FIGS. 1, 2 and 3. Embodiment 1 FIG. 1 is a sectional view of an essential part showing an example of the structure of a developing device according to the present invention. In FIG. 1, reference numeral 1 denotes a developing roller (for example, a diameter
An 18 mm developing roller) has a configuration in which the elastic layer 3 and the conductive layer 4 are provided concentrically on the outer periphery of the metal shaft 2, and has a peripheral speed V ₁ (mm / sec) counterclockwise in the figure. Rotate with. The surface conductive layer 4 of the developing roller 1 is electrically connected to the metal shaft 2, and a developing bias power source 6 is connected to the metal shaft 2 via a protective resistor 5. On the other hand, a rotary stirrer (rotary stirrer) 8 and a toner supply roller (for example, a toner supply roller having a diameter of 12 mm) 9 housed and mounted in the toner container 7 are provided on the surface of the developing roller 1. The toner is supplied, and the toner thin layer 11 having a uniform thickness is formed by the regulating action of the toner layer forming member 10. Thus, the toner layer 11 formed on the surface of the developing roller 1 comes into contact with a latent image holding member (for example, a photosensitive drum having a diameter of 30 mm) 12, and the latent image on the surface of the photosensitive drum 12 is developed. Further, in FIG. 1, 13 is a transfer device, 14
Denotes cleaning means and 15 denotes charging means. In this embodiment, an example is described in which a non-magnetic toner is attached to a latent image having a potential V ₀ of +550 V and a potential V _R of +120 V after exposure by a reversal development method. That is, the background potential and the image portion potential are
Corresponds to V ₀ and V _R. A developing bias Vb is applied to the conductive layer 4 of the developing roller 1. Specifically, the developing bias voltage Vb = 250 V, the surface speed V _{1 of the} developing roller ₁
= 180 mm / sec, the photosensitive drum 12 surface speed V ₂ = 90mm / se
c, The contact width between the photosensitive drum 12 and the developing roller 1 was set to 1 to 3 mm. The non-magnetic toner is a positively-charged one-component non-magnetic toner composed of a polyester resin, a pigment, a charge control agent, a wax, hydrophobic silica, and the like, and having a repose angle of 20 to 40 °. In the developing device having the above-mentioned structure, a member having a tip of a silicone rubber at the tip of a leaf spring is used as the toner layer regulating member 10, and the contact points of the developing roller 1 with the toner layer forming member 10 are denoted by a, The arc ab when the contact point with the toner supply roller 9 is set to b is 1 perimeter of the developing roller 1 circumference.
/ 6. Also, the toner supply roller 9
Is made of flexible urethane foam, JIS-K640
In Example 1, a material having a hardness of 40 KGF was used. As the toner supply auxiliary member 16, a phosphor bronze plate was disposed so that the contact depth with the toner supply roller 9 was 0.1 mm, and the bias of the phosphor bronze plate 16 was floating. A positively charged magenta toner was put into this developing device, and 50,000 sheets of an image having a printing rate of 5% were output at room temperature and normal humidity. The solid image density was set to an initial value ID = 1.5 (RD 9
18 reflection densitometer, measured by Macbeth)
The follow-up performance of the solid image was good throughout. Also photosensitive drum
The cover on 12 was less than 1% throughout. When the toner supply roller 9 was examined after the development, the toner was found to be free of electrostatic aggregation and clogging. Example 2 The same conditions as in Example 1 were used, except that a conductive material (carbon-dispersed polyurethane) having a surface resistance of 10 ⁶ Ω / port was used as the toner supply auxiliary member 16 instead of the phosphor bronze plate. As a result of the experiment, the solid image density maintained the initial value (ID = 1.5), and the followability of the solid image was good throughout. The fog on the photosensitive drum 12 was 1% or less throughout. Example 3 An experiment was performed under the same conditions as in Example 1 except that a bias of 350 V was applied to the toner supply roller 9 and the phosphor bronze plate of the toner supply auxiliary member 16 was set to the same potential as the toner supply roller 9.
The solid image density was maintained at the initial value (ID = 1.5), and the followability of the solid image was good throughout. The fog on the photosensitive drum 12 was 1% or less throughout. When the supply roller was examined after the completion of the development, there was no electrostatic aggregation of the toner and no clogging occurred. Example 4 An experiment was conducted under the same conditions as in Example 1 except that a bias of 350 V was applied to the toner supply roller and 450 V was applied to the phosphor bronze plate of the toner supply auxiliary member 16. ID = 1.5) was maintained, and the follow-up property of the solid image was good throughout. The fog on the photosensitive drum 12 was 1% or less throughout. When the supply roller was examined after the completion of the development, there was no electrostatic aggregation of the toner and no clogging occurred. Example 5 Example 1 was the same as Example 1 except that a bias of 350 V was applied to the toner supply roller 9 and a voltage of 250 V was applied to the phosphor bronze plate of the toner supply auxiliary member 16.
When the experiment was performed under the same conditions as in the above, the solid image density was maintained at the initial value (ID = 1.5), and the followability of the solid image was good throughout. The fog on the photosensitive drum 12 was 1% or less throughout. When the supply roller was examined after the completion of the development, there was no electrostatic aggregation of the toner and no clogging occurred. Embodiment 6 The embodiment is the same as the embodiment shown in FIG. 2, except that a toner supply auxiliary member (made of stainless steel) 16 'is slightly deformed as compared with the case shown in FIG. When the developing device was constructed in the same manner as in Example 1, and the experiment was conducted under the same conditions, the solid image density was maintained at the initial value (ID = 1.5), and the followability of the solid image was good throughout. The fog on the photosensitive drum 12 was 1% or less throughout. When the toner supply roller 9 was examined after the development, the toner was found to be free of electrostatic aggregation and clogging. Example 7 Development was performed in the same manner as in Example 1 except that a roller-type toner supply auxiliary member (made of phosphor bronze) 16 ″ was installed in a form as shown in cross section in FIG. When the apparatus was constructed and experiments were performed under the same conditions, the solid image density was set to the initial value (I.
D. = 1.5), and solid image follow-up was good throughout. The fog on the photosensitive drum 12 was 1% or less throughout. After the development, the supply roller was examined.
There was no electrostatic aggregation of the toner, and no clogging occurred. COMPARATIVE EXAMPLE 1 A developing device having the same configuration as that of the first embodiment was prepared except that the toner supply auxiliary member 16 was not provided, and development was performed under the same conditions as in the first embodiment. The initial value of the image density was ID = 1.0, which was lower than that of the example.
In addition, the ability to follow a solid image was reduced when printing about 2,000 sheets, and the trailing edge of the image was blurred after outputting 50,000 sheets (ID = 0.5). The initial value of the fog on the photosensitive drum 12 was 3%, and after outputting 50,000 sheets, it became 10% or more. When the toner supply roller 9 was inspected after the completion of the development, streak-like fixation due to electrostatic aggregation of the toner was found, and clogging occurred. The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. According to the first aspect of the present invention, the upper end of the toner supply roller is positioned below the upper end of the developing roller to not only prevent insufficient charging due to the toner's own weight, but also assist toner supply. The member is placed in contact with or close to the developing roller, and the point of contact of the toner layer forming member with the developing roller, the point of contact of the toner supply auxiliary member with the developing roller, and the like are fixed. The configuration of the toner supply mechanism with respect to the developing roller surface gives an appropriate change to the toner flow, rotates many times on the toner supply roller, prevents the developing roller and the toner layer forming member from being stressed, and causes fogging and the like. High-quality images can be obtained without the need. [0033] According to the invention of claim 1, the toner supply roller upper than the developing roller upper end is positioned below, not only to avoid such insufficiently charged by the toner own weight,
The toner supply auxiliary member having a surface resistance of 1012 Ω / port or less is arranged in contact with or close to the toner supply roller. By arranging the toner supply auxiliary member having conductivity in contact with or close to the above, electrostatic aggregation that is likely to occur due to excessive charging on the toner supply roller is easily prevented or reduced, and the toner is adjusted to an appropriate charge amount. Since the toner can be sequentially developed, the new toner charging and developing cycle becomes smooth. Therefore, it is possible to obtain a high-density image without fogging over a long period without causing toner sticking or clogging of the toner supply roller. In the first aspect of the present invention, when the toner supply auxiliary member is made of metal, the toner supply roller is made of JIS-K6401 and has a hardness of 80 kgf in order to appropriately suppress the charging effect and the electrostatic aggregation. When the following foamable flexible foam is used, the surface area increases, so that the frictional charging and conveyance of the toner are advantageously performed, or the shape of the toner supply auxiliary member is set to a part or a plane of an arc having a curvature radius of 1 mm or more. In this case, stripping of the toner on the toner supply roller and an increase in the driving torque are easily prevented, and the above-described operation and effect are further promoted because good toner transportability is ensured. [0035] Further, according to the invention of claim 1, the contact depth 1 between the toner supply assisting member and the toner supply roller -0.5mm
By setting ≦ l ≦ 0.5 mm, a change can easily be given to the toner flow rotating around the outer periphery of the toner supply roller, so that charging is prevented and electrostatic aggregation is effectively prevented . The functions and effects of the invention are further promoted.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a main part showing a first configuration example of a developing device according to the present invention. FIG. 2 is a sectional view of a main part showing a second configuration example of the developing device according to the present invention. FIG. 3 is a sectional view of a main part showing a third configuration example of the developing device according to the present invention. [Description of Signs] 1 ... Developing roller 2 ... Metal shaft 3 ... Elastic layer 4 ... Conductor layer 5 ... Protective resistor 6 ... Developing bias power supply 7 ... Toner container 8 ... Rotary stirrer 9 Toner supply roller 10 Toner layer regulating member 11 Toner thin layer 12 Latent image holder (photosensitive drum) 13 Transfer device 14 Cleaner 15 Chargers 16, 16 ', 16 ″ …… Toner supply auxiliary member

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Mitsutoshi Saito 1 Toshiba-cho, Komukai, Koyuki-ku, Kawasaki-shi, Kanagawa Prefecture Within the R & D Center of Toshiba Corporation (72) Masahiro Hosoya Toshiba Komukai, Ko-ku, Kawasaki-shi, Kanagawa No. 1, Toshiba Corporation R & D Center (56) References JP-A-7-44012 (JP, A) JP-A-5-27567 (JP, A) JP-A-6-175487 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) G03G 15/08 501

Claims (1)

(57) [Claim 1] A developing roller disposed opposite to a latent image holding member, and a toner supply roller disposed opposite to the developing roller and supplying toner onto the developing roller. A toner layer forming member for forming a thin layer of the toner supplied by the toner supply roller on the developing roller, and a component for developing the latent image of the latent image holding member with the thinned toner. In the non-magnetic toner developing device, the upper end of the toner supply roller is positioned lower than the upper end of the development roller, the toner supply roller and the development roller rotate in the same direction, and a contact point between the toner layer forming member and the upper surface of the development roller. the a, 1 / 8-1 / 3 arc ab of the developing roller circumferential length when the contact point between the toner supply roller and the developing roller on expressed by a and b, respectively, and to face the toner supply roller surface Anti is at ^{10 12 Ω} / □ or less vias
The toner supply auxiliary member to which the toner is applied is arranged, and
Contact depth between the toner supply roller and the toner supply auxiliary member
A one-component non-magnetic toner developing device, wherein 1 satisfies -0.5 mm ≦ l ≦ 0.5 mm .