JP2001265105A - Non-magnetic one-component developing device - Google Patents

Abstract

(57) [Object] To provide a non-magnetic one-component developing apparatus in which a load on a drive system is reduced and an abnormal image is not generated even in a low humidity environment. A supply roller for supplying toner while being pressed against a developing roller is provided with a core bar formed by cutting a SUM-22 material into a shaft shape having an appropriate diameter and electroless nickel plating with a thickness of 6 μm. And a urethane foam sponge formed into a tubular shape by imparting conductivity by including and dispersing carbon in the conductive foam 45, and a polyamide-based resin film containing carbon in the conductive resin body 46 and having a thickness of 80 to 150 μm. Is formed in a tube shape. Core bar 44 coated with urethane-based conductive adhesive in which carbon is dispersed
A conductive foam 45 is adhered and fixed on the above, the hardness of the conductive foam 45 at that time is set to ASKER-F 63 to 85 °, and a urethane adhesive is applied to the inside of the conductive resin body 46. Then, the conductive foam 45 is press-fitted and fixed. The conductivity of the supply roller 47 is set to 1 × 10 ⁷ Ω or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device, and more particularly, to a non-magnetic one-component developing device capable of reducing driving load and performing good development even in a low humidity environment.

[0002]

2. Description of the Related Art Conventionally, there has been a non-magnetic one-component developing apparatus for developing a latent image on an image carrier into a toner image using a non-magnetic one-component toner. Such a developing device is provided with a supply roller that supplies toner to an elastic developing roller that develops a latent image on the image carrier into a toner image. The supply roller uniformly applies the toner in the hopper onto the developing roller, and on the other hand, scrapes the toner remaining on the developing roller and returning from the developing roller.

In order to perform such an operation, the supply roller is pressed against the developing roller, and at the pressed portion, the peripheral surface is rotationally moved in a direction opposite to the rotation direction of the developing roller. However, if the pressing force is too strong, the developing roller is deformed. Therefore, as the structure of the supply roller, there is an example in which a sponge-like roller is used, or a structure in which an elastic body and a rubbery skin layer are sequentially wound on a center metal core in a roller shape. As a result, the pressure contact force with respect to the developing roller is reduced to prevent the developing roller from being deformed.

FIG. 4 is a view showing still another example of the supply roller, and is a cross-sectional view of the supply roller proposed by Japanese Patent Application Laid-Open No. 7-36273. The supply roller 1 shown in FIG.
It comprises a central metal core 2, a continuous foamed sponge 3 having a small cell shape thereon and a large cell density, and a continuous foamed sponge 4 having a large cell shape thereon and a small cell density. Also in this case, it is described that the pressing force to the developing roller is reduced, thereby preventing the deformation of the developing roller.

[0005]

However, the other developing roller, which rotates while being opposed to and in pressure contact with the supply roller, generally has a configuration in which a rubber such as silicone or urethane is placed on a central metal core. , That is, the surface is made of a rubber material. As described above, the peripheral surfaces of the developing roller and the supply roller are rotationally moved in opposite directions at the pressure contact portion.

As described above, in addition to the surface material having a large coefficient of friction such as sponge or rubber, the moving directions of the circumferential surfaces which are pressed and slid are different from each other. Great frictional resistance is working. For this reason, there is a problem that a large load is applied to a driving system such as a motor and a gear for driving these, and power consumption is large.

Further, the toner generally comprises a fluidity improver such as silica externally added thereto, but a large physical load is applied to the toner conveyed between the supply roller and the developing roller due to the frictional resistance described above. Then, a phenomenon occurs in which a part of the external additive is gradually buried in the toner, and the fluidity of the toner is reduced. Then, as the fluidity decreases, the toner eventually becomes a thin layer and adheres to the surface of the developing roller and the supply roller, causing a problem that the developing performance of the developing roller is deteriorated.

[0008] Further, a foamed sponge having a small cell shape and a large cell density and a foamed sponge having a large cell shape and a small cell density are superposed on the core metal of the supply roller shown in FIG. In a low-humidity environment where the chargeability of the toner is increased because the surface is a sponge having a cell shape, there is no problem in a solid printing portion or a line printing portion.
In an image portion having a halftone dot area ratio of about 75% to 25% below 33 lines, a problem that a spot-like abnormal image (rainfall-like image) with a trace of a sponge hole shape was formed occurred.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional circumstances,
An object of the present invention is to provide a non-magnetic one-component developing device which reduces the load on a driving system, maintains the developing performance of a developing roller at a high level, and does not generate an abnormal image even in a low humidity environment.

[0010]

The construction of the non-magnetic one-component developing device according to the present invention will be described below. The non-magnetic one-component developing device of the present invention includes a developing roller that carries a non-magnetic one-component toner accommodated in a hopper on its surface and transports the toner, and a regulating member that forms the toner in a thin layer on the developing roller. A toner supply roller that presses against the developing roller and supplies the toner to the developing roller at a position upstream of the regulating member in the conveying direction of the developing roller, and a non-magnetic layer that develops a latent image on the image carrier. In the component developing device, the toner supply roller includes a metal core, a conductive foam covering the metal core, and a conductive resin body covering the conductive foam.

The conductive foam is made of, for example, a urethane-based or silicon-based sponge, and has a hardness of ASKER-F63 or less when not covered with the conductive resin body. It is configured to be 85 °. Further, the conductive resin body may be, for example,
As described, it is made of a carbon-containing polyamide resin film, and is configured to have a thickness of 80 to 150 μm. Further, the toner supply roller is configured such that the conductivity is 1 × 10 ⁷ Ω or less, for example.

Thus, it is possible to provide a non-magnetic one-component developing apparatus in which the load on the driving system is reduced, the developing performance of the developing roller is maintained at a high level, and an abnormal image does not occur even in a low humidity environment.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view schematically showing an internal configuration of a color image forming apparatus including a non-magnetic one-component developing device according to an embodiment. First, the overall configuration will be described with reference to FIG. As shown in FIG. 1, the color image forming apparatus (main body apparatus) 10 includes an opening / closing tray 11 on a rear surface (left side in the figure) and a detachable lower part from the front side (right side in the figure) of the main body apparatus. A paper cassette 12 is provided. A large number of sheets are placed and stored in the sheet cassette 12. An upper lid 13 is provided on the upper surface of the main body device 10. A power switch, a liquid crystal display device, a plurality of input keys, and the like are arranged on the front side of the upper lid 13 although not shown in the drawing. The upper lid 13 forms a paper discharge tray 14 at the rear thereof together with the upper surface of the rear of the main body device 10.

Inside the main body device 10, a flat loop-shaped paper transport belt (hereinafter, simply referred to as "belt") 15 is disposed at substantially the center thereof so as to extend in the front-rear direction. It is held by a driving roller 16 and a driven roller 17. The belt 15 is driven by a driving roller 16 and circulates in a counterclockwise direction indicated by an arrow R in the figure. Four photosensitive drums 18 (18a, 18b, 18) serving as electrostatic latent image carriers are provided on the upper circulating portion of the belt 15.
c, 18d) are juxtaposed in a multi-stage manner in the sheet transport direction (from right to left in the figure). The cleaner 21, the initialization charging brush 22, the writing head 23, and the like surround the photosensitive drums 18 (typically, only the peripheral devices around the photosensitive drum 18 d are denoted by reference numerals).
And a developing device 24. Although not particularly shown, a contact-type transfer unit is in pressure contact with the photosensitive drum 18 via the belt 15 to form a transfer unit.

The developing unit 24 forms a developing unit by bringing a developing roller 25 as a toner carrier rotatably supported in a lower opening thereof into contact with the peripheral surface of the photosensitive drum 18.
The write head 23 is disposed on the back surface of the upper lid 13 via a support member 26, moves up and down in a circular locus as the upper lid 13 opens and closes, and descends when the upper lid 13 is closed. The recording section is formed by being positioned between the initialization charging brush 22 and the developing roller 25.

At the upstream end of the upper circulation portion of the belt 15,
The suction roller 27 is driven by the driven roller 17 via the belt 15.
To form a paper carrying portion. The suction roller 27 presses the paper conveyed to the paper conveyance unit against the belt 15 while applying a suction bias to the paper, and applies the belt 15.
Paper is electrostatically attracted to the paper.

The photosensitive drum 1 at the uppermost stream in the paper transport direction.
8a, the photosensitive drum 1 at the most downstream position from the developing device 24
Up to the developing device 24 corresponding to 8d, each developing device 24 has M (magenta), C (cyan), and three subtractive primary colors.
Each toner of Y (yellow) and Bk (black) toner dedicated to printing of a black portion of a character or an image are stored.

A pair of standby rollers 28 is disposed further upstream (to the right in the drawing) in the transport direction than the belt 15, and a paper feed guide path 29 is disposed below the standby roller pair 28. A roller pair 31 is provided. Feeding roller pair 31
The paper feed end of the paper cassette 12 described above is located upstream (below). A paper feed roller 32 is disposed above a paper feed end of the paper cassette 12. The paper feed roller 32 takes out one uppermost sheet stored in the paper cassette 12 and feeds it to the feed roller pair 31 every one rotation.

Downstream of the belt 15 in the paper transport direction (left side in the figure), a fixing device 33, a pair of paper discharge rollers 34, and a switching lever 35 are provided. The fixing device 33 includes a pressure roller, a fixing roller, a heating roller, a paper separating claw, a peripheral surface cleaner, an oil application member, a thermistor, and the like, which are assembled in a heat insulating housing, and a toner image transferred onto the paper. Is heat-fixed to the paper surface.

When the switching lever 35 is at the lower position as shown in FIG. 1, it guides the sheet to be discharged to the discharge tray 14 via the upper discharge path 36 and the pair of discharge rollers 37. On the other hand, when rotating upward, the sheet is guided to the opening / closing tray 11 opened on the rear surface of the main unit.

An electrical unit 38 on which a circuit board can be mounted is provided between the belt 15 and the paper cassette 12, and a control device including a plurality of electronic components is mounted on the circuit board. Although not specifically shown, the control device includes a controller unit and an engine unit, and the controller unit includes a CPU (Central Processing Unit), a ROM (Read Only Memory), an EEP
It includes a ROM (rewritable read memory), a frame memory, an image data transfer circuit, and the like, analyzes print data input from a host computer or the like, creates print data, and transfers the print data to the engine unit.

The engine unit includes a CPU, a ROM, and the like.
On the input side, data and command signals from the controller unit, the output of the temperature sensor, the output of the paper detection sensor, etc. are input, and on the output side, a motor driver that drives a motor (not shown), and the drive of the motor is transmitted to each unit. Driver for switching the driving system to be performed, a print driver for driving the write head 23 based on the print data, an initialization charging brush 2
2. A bias power supply driver for supplying a predetermined bias voltage to a developing roller 25, a transfer device, a suction roller 27, a supply roller described later, a doctor blade, a scooping sheet, and the like are connected. The engine unit controls the driving of each unit based on data and command signals from the controller unit, the output of the temperature sensor, the output of the sheet detection sensor, and the like.

FIG. 2 is an enlarged side sectional view schematically showing a main part of the developing unit 24. As shown in FIG. As shown in the figure, the developing device 24 includes a hopper 41, and the developing roller 25 described above is rotatably held in a lower opening of the hopper 41. Inside the hopper 41, a non-magnetic one-component toner 42 is provided. A stirring member 43 is provided so as to be accommodated and buried in the toner 42.

At the bottom of the hopper 41, a supply roller 47, which will be described in detail later, is provided with a developing roller 2.
5 and is disposed in pressure contact with it. The developing roller 25 is provided with a leaf spring-shaped doctor blade 48 for pressing the toner layer to a predetermined thickness by pressing in a rotational direction (counterclockwise direction in the drawing) downstream of the pressure contact portion with the supply roller 47. A conductive scooping sheet 49 is provided in contact with the lower peripheral surface.

When a toner charged to a weak negative potential is used as in this embodiment, the developing roller 25 is supplied with a negative power from the bias power supply 51 in order to form a stable toner image on the photosensitive drum 18. Of the developing bias voltage “−250 V” is applied. Further, a negative supply bias voltage “−500 V” is applied to the supply roller 47 from another bias power supply 52, and a force is applied so that the toner 42 is electrically transferred from the supply roller 47 to the developing roller 25. Electric field is applied.

The doctor blade 48 is formed such that the bending angle of the distal end is acute and has a predetermined bending radius, and is disposed at a predetermined narrow angle with respect to a tangent line of a contact portion with the developing roller 25. To do. Furthermore, scooping sheet 4
Although not shown in the figure, a large number of fine openings are preferably formed obliquely and provided so as to be in sliding contact with the peripheral surface of the developing roller 25.
3 is applied.

The basic operation of the color image forming apparatus 10 having the above configuration will be described below again with reference to FIGS. First, when the power is turned on and the paper quality, the number of sheets to be used, the print mode, and other designations are input as a key input or as a signal from a connected host device,
The paper feed roller 32 makes one rotation by a drive mechanism (not shown), and feeds the paper loaded and stored in the paper cassette 12 to the standby roller pair 28 via the feed roller pair 31. The standby roller pair 28 temporarily stops rotating, and waits for the transport timing in a state where the leading end of the sheet is brought into contact with the holding portion formed by the pair of rollers.

Subsequently, the driving roller 16 rotates in the counterclockwise direction, and the driven roller 17 is driven to rotate in the same counterclockwise direction. As a result, the upper circulating portion of the belt 15 abuts on the four photosensitive drums 18 and circulates in the counterclockwise direction as a whole as shown by the arrow B in the figure.

At the same time, the developing units 24 and the photosensitive drum 18 are sequentially driven in accordance with the printing timing. The photosensitive drum 18 rotates clockwise, the initialization charging brush 22 applies a uniform high negative charge to the peripheral surface of the photosensitive drum 18, and the writing head 23 controls the photosensitive drum 18.
The peripheral surface is exposed according to the image signal. As a result, an electrostatic latent image composed of the high negative potential portion due to the initialization and the low negative potential portion whose potential has been attenuated by exposure is formed.

The agitating member 43 feeds the toner 42 toward the supply roller 47 while giving a weak negative charge due to frictional charging while constantly stirring so as not to solidify the toner 42. The supply roller 47 supplies the toner 42 to the peripheral surface of the developing roller 25 so as to rub it. The doctor blade 48 is used to transfer the toner 4
2 is regulated to a predetermined constant thickness, and the toner 42 is caused to adhere to the developing roller 25 by applying a voltage from a bias power supply (not shown).

The developing roller 25 rotationally conveys the toner 42 to a portion facing the photosensitive drum 18. The low potential portion of the electrostatic latent image on the peripheral surface of the photosensitive drum 18 has a minus potential weaker than the minus potential of the developing roller 25 by the bias power supply 51, and is relatively positive with respect to the developing roller 25 and the toner 42. It is at potential. This allows
The toner 42 transfers to the low potential portion of the electrostatic latent image on the photosensitive drum 18 and forms a toner image on the peripheral surface of the photosensitive drum 18 (reversal development).

When the leading end of the toner image on the peripheral surface of the photosensitive drum 18a at the most upstream position is rotated and conveyed to the portion facing the belt 15, the printing start position of the paper coincides with the facing portion. The standby roller pair 28 starts rotating and feeds the sheet to the sheet carry-in section. The driven roller 17 and the suction roller 27 hold and transport the fed sheet together with the belt 15. The sheet is attracted to the belt 15 and is conveyed to the first transfer section formed by the photosensitive drum 18a and the transfer device.

The transfer unit applies a transfer current output from a transfer bias power supply to the sheet via the belt 15. The transfer current applied from the transfer device causes the photosensitive drum 18
The M (magenta) toner image on a is transferred to the sheet.
Subsequently, the C (cyan) toner image is transferred at the second transfer portion from the upstream formed by the photoconductor drum 18b and the transfer device, and is further transferred from the upstream formed by the photoconductor drum 18c and the transfer device. The Y (yellow) toner image is transferred at the second transfer portion. Then, a Bk (black) toner image is sequentially transferred at a most downstream transfer portion formed by the photosensitive drum 18d and the transfer device.

The sheet on which the four color toner images have been transferred in this manner is separated from the belt 15 and carried into the fixing device 33. The fixing device 33 fixes the toner image on the sheet by heat and pressure. After the image is fixed, the sheet is discharged by the discharge roller pair 34 with the toner image facing up on the opening / closing tray 11 on the rear surface or the toner image facing down on the upper discharge tray 14.

By the way, in the color image forming apparatus provided with the non-magnetic one-component developing device of this embodiment which operates as described above, the driving load on the driving system described above is reduced, and even in a low-humidity environment, a rain-like image can be obtained. The developing device 24 is specially devised so as to perform good development that does not produce a bad image.

In the first place, a defective image such as a rainy image in the above-described conventional example has a different charging characteristic of toner supplied to the surface of the developing roller between a portion corresponding to a hole on the sponge surface of the supply roller and other portions. It is thought to occur in.

Further, when searching for the cause, the supply roller has a function of removing the toner that has not been developed in the developing section and returns to the portion in contact with the supply roller while remaining on the development roller. It is charged by friction,
It can be seen that the action of removing the charged toner is weak at the portion corresponding to the hole on the sponge surface, and the tendency to remain on the developing roller is strong.

Then, on the remaining toner, the toner is newly supplied from the supply roller and further regulated by the doctor blade. Therefore, the charge amount of the toner at the portion corresponding to the rear portion on the sponge surface is the same as that of the other portion. It becomes higher than the charge amount. Since the development start potential of the toner in the portion where the charge is higher than the other portions is lowered, the solid development is performed with respect to the halftone potential of the halftone portion formed by fine halftons,
Since the solid spot of the hole shape on the sponge surface occurs in the fine halftone image, it is considered that the above-mentioned rainy image is formed.

Based on these facts, as a result of various studies, a special configuration is incorporated in the developing device 24 of this embodiment. FIG. 3A shows the developing device 2 of the present embodiment shown in FIG.
FIG. 4 is a detailed side cross-sectional view of a supply roller 47 assembled in the fourth embodiment. FIG. 3B is a diagram showing another configuration of the developing device 24. The supply roller 47 according to the present invention shown in FIG. 3A includes a core 44, a conductive foam 45 covering the core 44, and a conductive resin 46 covering the conductive foam 45. Become.

As the core metal 44, a SUM-22 material cut into a shaft having an appropriate diameter and subjected to electroless nickel plating with a thickness of 6 μm is used. As the conductive foam 45 covering the metal core 44, a foamed urethane sponge which is formed into a tubular shape with conductivity by containing and dispersing carbon is used. Needless to say, a silicon-based sponge containing and dispersing carbon similarly may be used.

Then, a urethane-based conductive adhesive in which carbon is dispersed is applied to the cored bar 44, and the conductive foam 45 is bonded and fixed thereon. At this time, the hardness of the conductive foam 45, that is, the hardness in a state where the conductive resin body is not yet covered with the conductive resin body, is equal to the ASKER-F.
It is set to be 63 to 85 °.

The conductive resin body 46 coated thereon has the following:
A carbon-containing polyamide resin film formed in a tube shape is used. The thickness of the carbon-containing polyamide resin film is 80 to 150 μm.
m is used. Then, while rotating the conductive foam 45 attached to the cored bar 44 at a constant speed, a urethane-based adhesive is sprayed on the surface thereof by a spray gun, and then applied to the inside of the tubular conductive resin body 46. Press fit
Thereafter, the adhesive is cured by heating, and the conductive foam 45 and the conductive resin body 46 are fixed to each other. The supply roller 47 finally formed in this way is configured to have a conductivity of 1 × 10 ⁷ Ω or less.

In the above-described configuration, while performing trial and error, such as changing the conditions of various constituent requirements, the configuration is used to form an image in practice in an environment corresponding to an actual use environment. Are finally determined based on the evaluation obtained by

When an image is formed by the developing device 24 using the supply roller having the above configuration, the toner flowing back into the developing device without participating in the development is supplied from the developing roller by the supply roller. It was confirmed that the toner was uniformly removed, fresh toner was supplied thereafter, and a fresh and uniform toner layer was formed on the developing roller.

Then, using the developing device 24, a temperature of 10
In a low humidity environment of 20 ° C and 20% humidity, 1 per 25.4 mm
When a halftone image with a halftone dot area ratio of 50% was printed at a drawing density of 33 lines, a uniform halftone image free from a rainfall phenomenon could be obtained.

Here, just in case, ASK is used as a comparative example.
Using a supply roller having an ER-F hardness of 68 ° and the same diameter but not coated with a tube, a dot density of 133 lines per 25.4 mm in an environment of the same temperature of 10 ° C. and humidity of 20% as described above. When a halftone image having an area ratio of 50% was printed, a non-uniform halftone image having a severe rainfall phenomenon was formed.

In such a developing device, even if the structure of the supply roller is improved as described above, the toner has a hygroscopic property. That is, the density at the time of forming an image may change. In order to detect this change in environmental humidity, in a conventional image forming apparatus, a humidity sensor is attached to the image forming apparatus main body. This was considered natural for the purpose of detecting environmental humidity.

However, if the humidity sensor is provided on the image forming apparatus main body side as described above, the environmental humidity can be detected, but the humidity environment inside the developing device is unknown, and it is difficult to detect the environmental humidity. Neither can the degree of moisture absorption of the toner be reflected. For this reason, there remains a problem that the influence of uncertain factors due to the difference in humidity inside and outside the developing device and the environmental history cannot be removed.

The developing device of this embodiment is designed so that more preferable control can be performed than the control of the developing condition by the humidity sensor provided in the ordinary image forming apparatus as described above.

That is, although the explanation is omitted in FIG. 2,
In the developing device 24, a sensor probe 54 as shown in FIG. 3 (b) is installed near the doctor blade 48. The sensor probe 54 includes two opposing electrodes 55a and 5 that are arranged at a predetermined interval.
5b and transmission lines 56a and 56b connected to these electrodes 55a and 55b, respectively. Transmission line 56a
And 56b are connected to the input side of the capacity meter 57 (see FIG. 2). The output of the capacity meter 57 is the doctor blade 48
Is connected to an output control system of a bias power supply (not shown). The purpose of this sensor probe 54 is not to measure the humidity of the toner, but to measure the dielectric constant of the toner flowing between the electrodes 55a and 55b.

In general, the force F that the electric field acting between the flat plates pulls the dielectric is V, the potential difference applied between the flat plates, the distance between the flat plates is d, and the dielectric constants of the dielectric and the atmosphere are ε ₂ and ε ₀ , respectively.
Then, F = (ε ₂ −ε ₀ ) · V ₂ / 2d. If this is applied between the developing roller 25 and the doctor blade 48 of the developing device 24, ε ₂ is the dielectric constant of the toner as a dielectric, and this increases due to the moisture absorption of the toner. It is considered that the force applied to the toner when trying to pass through the gap increases, and this affects the layer pressure of the toner on the developing roller 25. In particular, it is considered that there is a great effect on the initial image immediately after the power is turned on, in which the toner is low in the frictional charge caused by stirring.

Therefore, as shown in FIG. 3 (b), a capacitor-like sensor probe 54 is formed so that the flowing toner 42 can be used as a dielectric layer.
As shown in (2), it is installed in the developing device 24, and by detecting its capacitance, the toner 4
2 is accurately measured, and the doctor blade 48
And a bias voltage applied to the doctor blade 48 is controlled based on the above equation.

Generally, the dielectric constant due to water (that is, the humidity sucked by the toner 42) is several tens of times the dielectric constant of the resin (that is, the toner 42 itself). Rather, by controlling using the above method, an accurate and stable toner layer thickness can be obtained.

[0054]

As described above in detail, according to the present invention, the structure of the supply roller for supplying the toner by pressing against the developing roller of the non-magnetic one-component developing device is SUM- cut into an appropriate shape. A 22-shaft shaft is coated with a 6 μm-thick electroless nickel-plated mandrel 44, and carbon is included and dispersed in the shaft to give conductivity and form a cylindrical urethane foam sponge with a hardness of ASKER-F 63-85 °. Coated with a porous foam 45, on which a carbon-containing thickness of 80 to 1
The tube-shaped conductive resin body 46 made of a 50-μm polyamide resin film is adhered and formed so that the overall conductivity is 1 × 10 ⁷ Ω or less. For example, the temperature is 10 ° C. and the humidity is 20%. 25.4m in low humidity environment
Even when a halftone image with a drawing density of 133 lines per m and a halftone dot area ratio of 50% is printed, a uniform halftone image free of a rainfall phenomenon can be obtained, and thereby the friction between the developing roller and the supply roller can be obtained. It is possible to provide a non-magnetic one-component developing device in which the resistance is low, the load on the drive system is reduced, and an abnormal image is not generated even in a low humidity environment.

[Brief description of the drawings]

FIG. 1 is a side sectional view schematically showing an internal configuration of a color image forming apparatus provided with a non-magnetic one-component developing device according to an embodiment.

FIG. 2 is an enlarged side sectional view schematically showing a main part of a developing device (non-magnetic one-component developing device) according to one embodiment.

FIG. 3A is a detailed side sectional view of a supply roller assembled to the developing device of the present embodiment, and FIG. 3B is a diagram illustrating another configuration of the developing device.

FIG. 4 is a cross-sectional view illustrating an example of a conventional supply roller.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 supply roller 2 cored bar 3 foam sponge with high cell density 4 foam sponge with low cell density 10 color image forming apparatus (main unit) 11 opening / closing tray 12 paper cassette 13 top lid 14 paper discharge tray 15 belt (paper transport belt) Reference Signs List 16 drive roller 17 driven roller 18 (18a, 18b, 18c, 18d) photoreceptor drum 19 writing head insertion groove 21 cleaner 22 initialization charging brush 23 writing head 24 developing device 25 developing roller 26 support member 27 suction roller 28 standby Roller pair 29 Feed guide path 31 Feed roller pair 32 Feed roller 33 Fixer 34 Discharge roller pair 35 Switching lever 36 Discharge path 37 Discharge roller pair 38 Electrical unit 41 Hopper 42 Toner 43 Stirrer 44 Core metal 45 Conductive Foam 46 Conductive resin 47 Supply roller 48 Doctor blade 49 Scooping sheet 51, 52, 53 Bias power supply 54 Sensor probe 55a, 55b Electrode 56a, 56b Transmission line 57 Capacity meter

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) // C08L 77:00 C08L 77:00 (72) Inventor Masafumi Nakahara 2-229 Sakuragaoka, Higashiyamato-shi, Tokyo F term in Casio Computer Co., Ltd. Tokyo office (reference) AA54 AA67 AB03 AF25 AF37Y AH12 BB09 BC01 BC07 BC12

Claims (4)

[Claims] A developing roller configured to carry a non-magnetic one-component toner stored in a hopper on a surface thereof and to convey the toner; a regulating member configured to form the toner in a thin layer on the developing roller;
A non-magnetic mono-component for developing a latent image on an image carrier, comprising: a toner supply roller that presses against the developing roller and supplies the toner to the developing roller at a position upstream of the regulating member in the conveying direction of the developing roller. In the developing device, the toner supply roller includes: a core bar; a conductive foam covering the core bar; and a conductive resin body covering the conductive foam. Component developing device. 2. The conductive foam comprises a urethane-based or silicon-based sponge, and has a hardness of ASKER-F 63 to 85 when not covered with the conductive resin body.
2. The non-magnetic one-component developing device according to claim 1, wherein the angle is °. 3. The conductive resin body is made of a polyamide resin film containing carbon and has a thickness of 80 to 1
2. The non-magnetic one-component developing device according to claim 1, wherein the thickness is 50 [mu] m. 4. The toner supply roller has a conductivity of 1 ×.
2. The non-magnetic one-component developing device according to claim 1, wherein the non-magnetic one-component developing device has a resistance of 10 ⁷ Ω or less.