JP2001092248A - Developing machine and nonmagnetic one-component developing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing machine and a nonmagnetic one-component developing method, in which unwanted toner is not stuck to a developing roller or a doctor blade. SOLUTION: A doctor blade 45 is formed so that the bend angle of its edge is an acute acute, and a bend radius R thereof satisfies 0.25 mm<R<0.45 mm and is arranged at the angle of 0 deg. to 90 deg., desirably, 15 deg. to 20 deg. to the tangent of its abutting part on a developing roller 25. The bias voltage applied to the doctor blade 45 from a bias power source 49 is changed to a low bias voltage under high humidity and to high bias voltage under low humidity. Thus, toner clogging is eliminated, regardless of ambient humidity and a uniform and thin toner layer is always formed between the doctor blade 45 and the developing roller 25, so that a good quality image which is uniformly electrified and has neither fogging nor blurring.

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 a non-magnetic one-component developing method in which unnecessary toner does not adhere to a developing roller or a doctor blade.

[0002]

2. Description of the Related Art Conventionally, there is an electrophotographic image forming apparatus. Normally, this image forming apparatus includes a series of image forming processes of forming an electrostatic latent image on a photoconductor, forming the electrostatic latent image into a toner image (developing), and transporting the toner image to a position where the toner image is transferred to a sheet. The image forming unit for performing the above is incorporated.

FIG. 8 is a side sectional view showing a main part of such an image forming unit. Developing unit 1 shown in FIG.
Includes a photosensitive drum 2, a developing roller 3 that is in pressure contact with the photosensitive drum 2, and a toner container 4 that rotatably supports the developing roller 3 in an opening on a lower side surface. , Toner 5, and a stirrer 6, a supply roller 7, a doctor blade 8, a scooping sheet 9, and the like, which are disposed so as to be buried in the toner 5. The photosensitive drum 2, the developing roller 3 and the supply roller 7 rotate in the directions indicated by arrows in FIG.

The photoreceptor drum 2 is formed by uniformly applying a photoconductive member on the surface of a conductive metal roller, and an electrostatic latent image is formed on a peripheral surface formed of the photoconductive member to rotate the photoconductive member. I do.
The developing roller 3 is formed, for example, by applying a semiconductive urethane rubber around a metal core, a bias voltage is applied to the core, and the toner 5 is carried and conveyed on the surface to form the toner on the photosensitive drum 2. Is formed (developed) into a toner image. Stirrer 6
Is stirred so that the toner 5 in the toner container 4 is not solidified.

[0005] The supply roller 7 is also formed by coating a semiconductive urethane rubber around a metal core, and is arranged so that the urethane rubber layer on the surface is pressed against the developing roller 3. The toner 5 is once scraped off, and the fresh toner 5 stirred by the stirrer 6 is supplied to the developing roller 3. The doctor blade 8 serving as a toner regulating member is provided with a tip of a stainless steel plate having a spring property.
The toner 5 is guided between the doctor blade 8 and the developing roller 3 by the tip bent at an obtuse angle that is bent at an obtuse angle larger than the degree, and is disposed so that the bent portion is in contact with the developing roller 3. The toner 5 attached to the developing roller 3 is thinned to a predetermined thickness and the toner 5
Is given an appropriate triboelectric charge. The scooping sheet 9 is configured to prevent the leakage of the toner 5 in the toner container 4 and to allow the toner 5 remaining on the developing roller 3 to enter the toner container 4.

Although not particularly shown, a negative bias voltage is applied to the core of the developing roller 3, and a negative bias voltage is also applied to the other doctor blade 8. Conventionally, the toner 5
The negative bias voltage of the doctor blade 8 is considerably higher than the negative bias voltage of the developing roller 3 so as to compensate for the insufficient supply power of The toner 5 charged to a weak polarity is attracted to the developing roller 3. As a result, most of the toner 5 escapes from the doctor blade 8 into the toner container 4 as shown by the arrow A in the figure, and the other portion is attracted to the developing roller 3 by the electric field and the surface of the developing roller 3 And is transferred to the image portion of the electrostatic latent image on the peripheral surface of the photosensitive drum 2.

[0007]

By the way, in the above configuration, it is necessary to provide a sufficient charge to the toner 5 to obtain a high-quality image free from background fogging (toner stain on a non-image portion, ie, a white background portion). In addition, it is necessary to press the doctor blade 8 against the developing roller 3 with a considerably large pressure to regulate the layer thickness of the toner 5 to a constant value and frictionally charge the toner.

However, when a large pressure is applied to the toner 5 on the developing roller 3 as described above, the pressure and the heat generated by the friction cause the resin component of the toner 5 (the non-magnetic one-component toner has a fluidity). (Silica, which is a hydrophobic resin, is externally added for the sake of improvement.) Melt and agglomerate, and these are embedded in the surface layer of the sponge body of the developing roller 3 or fixed to the tip of the doctor blade 8. I do.

When the aggregated toner is embedded in the surface layer of the developing roller 3 or adheres to the tip of the doctor blade 8, a uniform toner layer cannot be formed on the developing roller 3, so that the photosensitive drum 2, the electrostatic latent image could not be developed correctly, which hindered image formation.

As described above, a relatively large potential difference is formed between the doctor blade 8 and the developing roller 3 in order to reinforce the toner supply force of the supply roller 7. The electric field from the doctor blade 8 to the developing roller 3 forms a repulsive force between the toner 5 and the doctor blade 8, which is a factor that hinders the triboelectric charging of the toner by the doctor blade 8.

When the relative humidity of the environment increases, the toner 5 absorbs moisture and the chargeability decreases. As a result, the amount of low-charge toner and toner of the opposite polarity increases, and these toners adhere to the photosensitive drum 2 regardless of the potential of the electrostatic latent image or against it. In other words, the above-described background fogging phenomenon in which the toner is transferred to the white print occurs here again, causing a problem of deteriorating the image quality.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances,
An object of the present invention is to provide a developing device and a non-magnetic one-component developing method in which unnecessary toner does not adhere to a developing roller or a doctor blade.

[0013]

According to the first aspect of the present invention, there is provided a developing device for controlling at least a toner carrier for carrying and conveying toner and a thickness of the toner on the toner carrier. A developing device comprising a toner layer regulating member, wherein the toner layer regulating member is disposed with its tip abutting in a direction opposite to the rotation direction of the toner carrier, and the bending angle of the tip is Acute angle and bending radius R
Is set such that 0.25 mm <R <0.45 mm.

[0014] The toner layer regulating member is preferably, for example,
As described, the tangent line formed on the peripheral surface of the toner carrier at the contact portion with the toner carrier is 0 ° to 9 °.
It is arranged at an angle of 0 °, preferably 15 ° to 20 °.

A predetermined voltage is applied to the toner carrier and the toner layer regulating member, respectively, and a voltage is formed between the toner carrier and the toner layer regulating member by the voltage. The applied electric field does not exert a force on the charged toner having the polarity to be normally developed, or acts in a direction of peeling the toner from the toner carrier.

The voltage applied to the toner layer regulating member is set so as to change according to the environmental humidity. Next, in the developing device according to the fifth aspect of the present invention, a scooping sheet that is in contact with a developing roller is disposed downstream of a developing unit that develops an electrostatic latent image on an electrostatic latent image carrier by a non-magnetic one-component developing method. The scooping sheet is a thin plate member made of an elastic material, and is provided with a grid-shaped crossbar to physically remove toner remaining on the developing roller without contributing to development. It has a partitioned opening, and is arranged and arranged so that a part or all of the crosspiece obliquely intersects the longitudinal direction of the developing roller and is in contact therewith.

The scooping sheet is configured to be applied with a predetermined voltage in order to remove a defective potential remaining on the developing roller, for example, as set forth in claim 6. As described above, the opening ratio of the opening is 75
%, And the angle at which the longitudinal direction of the developing roller obliquely intersects the crosspiece that partitions the opening and is 15 °.
４５45 °. Further, for example, as in claim 8, further comprising a variable voltage applying means for variably applying the predetermined voltage according to the relative humidity, wherein the variable voltage applying means is provided when the relative humidity becomes 30% or less. The predetermined voltage is varied so as to be closer to the ground voltage.

Further, in the non-magnetic one-component developing method according to the ninth aspect of the present invention, the toner contains 0.5% by weight of hydrophobic silica to 2% by weight.
A non-magnetic one-component developing method using a non-magnetic toner externally added by weight%, wherein the toner has a particle size of 5 μm or less, a weight distribution of 4% or less, preferably 3% or less, and a CV value of 27 or less, preferably 24 or less.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side cross-sectional view schematically illustrating an internal configuration of a color image forming apparatus equipped with a developing device as a 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. In addition, the upper cover 1
3 is provided. 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 rear part of the upper lid 13 is
A discharge tray 14 is formed together with the rear upper surface.

A flat loop-shaped paper transport belt (hereinafter simply referred to as a belt) 15 is disposed substantially in the center of the main body device 10 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).

Each of the photosensitive drums 18 is encircled (typically, only the peripheral devices around the photosensitive drum 18d are denoted by reference numerals),
Initializing charging brush 22, writing head 23, and developing device 2
4 are arranged. Although not shown, a contact-type transfer unit is connected to the photosensitive drum 18 via the belt 15.
To form a transfer portion.

The developing unit 24 has a developing unit formed 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.

On the further upstream side (right side in the drawing) of the belt 15 in the transport direction, a standby roller pair 28 is disposed, 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.

On the other hand, a fixing device 33, a pair of paper discharge rollers 34, and a switching lever 35 are provided downstream of the belt 15 in the paper transport direction (left side in the drawing). The fixing device 33 includes a pressure contact roller, a fixing roller, a heating roller, a paper separating claw, a peripheral surface cleaner, an oil applying member,
It is composed of a thermistor or the like, and heat-fixes the toner image transferred on the paper to the paper surface.

When the switching lever 35 is at the lower position as shown in the figure, it guides the paper to be discharged to the paper discharge tray 14 via the upper discharge path 36 and the paper discharge roller pair 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.

Hereinafter, a basic operation of the color image forming apparatus 10 will be described. 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 a signal from a host device to be connected, the feed roller 32 is driven by a drive mechanism (not shown). By rotating, the paper loaded in the paper cassette 12 is fed 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 developing roller 25 of the developing device 24 transfers the toner to the low potential portion of the electrostatic latent image to form a toner image on the peripheral surface of the photosensitive drum 18 (reversal development).

At the timing 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 thermally fixes the toner image on the paper. 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.

In the color image forming apparatus 10 according to the present embodiment, which operates as described above, the developing device 24 is specially designed to form a stable toner image on the photosensitive drum 18. I have. Hereinafter, this will be described.

FIG. 2 is a side sectional view schematically showing a main part of the developing unit 24. As shown in the drawing, the developing device 24 is assembled with the above-described photosensitive drum 18, the cleaner 21, the initialization charging brush 22, and the like.
The image forming unit 40 is formed together with the drum unit 39 on which the image forming unit 9 is formed.

The basic configuration of the developing unit 24 shown in FIG. 8 is the same as that of the developing unit 24 shown in FIG.
Is substantially the same as the configuration of the developing unit 1 shown in FIG. That is, the developing device 24 includes a housing 41 also serving as a toner hopper, and the developing roller 25 described above is provided at a lower opening of the housing 41.
Is rotatably held, and a housing 41 is provided with a stirring member 43 that accommodates a nonmagnetic one-component toner 42 and is disposed so as to be buried in the toner 42.

A supply roller 44 formed of a sponge body is disposed at the lowermost portion in pressure contact with the developing roller 25.
The developing roller 25 is provided with a leaf spring-shaped doctor blade 45 as a toner layer regulating member that is pressed against the downstream side in the rotation direction (counterclockwise direction in the drawing) from the pressing portion.
Further, a conductive scooping sheet 46 is disposed in contact with the lower peripheral surface.

The following is a description of experiments conducted by the inventor for elucidating the above-mentioned problems of the prior art, and points obtained by examining the results thereof, in forming the present invention. Generally, the amount of frictional charge of the toner 42 is, as described with reference to FIG. 8, an adhesion phenomenon to a non-image portion which is a problem that occurs during development (called a photoreceptor fog, and a fog on an image formed on the paper surface causes a background fog). (Hereinafter simply referred to as "cover")
Has a close relationship with the toner 42 having a small charge amount.
As described above, fogging is easily generated. However,
Experiments have shown that the triboelectric charge of the toner 42 is easily affected by humidity.

Specifically, when the amount of water contained in the toner 42 is 0.8% or more of the whole, the charge amount is reduced, and fog is noticeable. More specifically, “−500 V” is applied to the core of the supply roller 44 and “−500 V” is applied to the doctor blade 45.
V and the core of the developing roller 25 to which a bias voltage of -250 V is applied, the non-magnetic one-component toner 42 is charged into the developing device 24 to perform printing. In a humid environment, good results are obtained with an appropriate image density and no fogging. However, fogging occurs in a high humidity environment.

Therefore, when various experiments were repeated, it was found that when the bias voltage of the doctor blade 45 was close to the bias voltage of the developing roller 25, fogging disappeared and good results were obtained. For example, when the bias voltage applied to the doctor blade 45 is set to the same “−250 V” as the bias voltage applied to the developing roller 25, fog hardly occurs.

When the bias voltage of the doctor blade 45 was gradually increased to "-300 V", "-350 V",..., It was found that fogging occurred and the degree of fogging increased as the bias voltage was increased. did.

Here, when observing the movement of the toner near the doctor blade, when the applied bias voltage is set to a high voltage, the movement of the toner at the contact point between the doctor blade and the developing roller is remarkably deteriorated. That is, when the applied bias of the doctor blade is a high voltage, the electric field between the developing roller and the doctor blade becomes strong, and the toner is pressed against the developing roller. As a result, the toner passing through the doctor blade is compressed and passes at a high density. In other words, toner having a high toner density and insufficient frictional charging between the doctor blade and the toner, which is generated when the toner passes through the doctor blade, is generated. As a result,
Fogging occurs.

Conversely, when the bias voltage of the doctor blade is reduced, the movement of the toner is improved, and the toner is rebounded by the doctor blade. In other words, when the applied bias of the doctor blade is low, the density of the toner passing through the doctor blade is reduced and the frictional charging is sufficient, so that the fog is reduced.
From this, it is clear that the problem of fogging generated under high humidity can be solved to some extent by lowering the bias voltage of the doctor blade.

However, when the same bias voltage of -250 V as the bias voltage of the developing roller 25 was applied to the doctor blade 45 and continuous printing was performed in a low humidity environment, the latter half of the solid image was printed as the number of prints increased. The problem of blurring, that is, insufficient supply of the toner 42, has occurred. This problem is significant in a low humidity environment and not so much in a high humidity environment.

This is because the bias voltage of the doctor blade 45 is set to be the same as the bias voltage of the developing roller 25, so that the developing roller 2
5, the adhesion of the toner 42 to the toner 4 is weakened.
This is considered to be because the amount of adhesion of the second to the developing roller 25 is limited to the amount of adhesion due to the supply force of the supply roller 44 to the developing roller 25 and the amount of adhesion due to physical guidance of the tip of the doctor blade 45.

The reason that the toner supply is not insufficient under the high humidity is that the electric resistance is lowered due to the high humidity because the surface layers of the developing roller 25 and the supply roller 44 are both made of the urethane layer. A strong electric field which is repelled from the supply roller 44 and drawn toward the development roller 25 acts on the toner 42 existing between the development roller 25 and the supply roller 44, and the toner 4 from the supply roller 44 to the development roller 25 is actuated.
It is considered that this is because the supply amount of No. 2 becomes relatively large.

On the other hand, the reason why the toner supply is insufficient under low humidity is that the electric resistance of both the developing roller 25 and the supply roller 44 becomes high at low humidity, so that the toner
It is considered that the electric field to the second roller 2 is weakened, and the supply amount of the toner 42 from the supply roller 44 to the developing roller 25 is reduced.

Therefore, in a low humidity condition, it is essential to supply a sufficient amount of the toner 42 by the doctor blade 45. Therefore, if the bias voltage of the doctor blade 45 is set to a constant high pressure as in the prior art, fogging occurs at a high humidity. Doing was mentioned above. As described above, preventing blurring of a solid image and preventing fogging from occurring are incompatible.

In development, it is known that a phenomenon called a ghost image different from the above-mentioned “fog” or “blurring” occurs. The ghost image is a phenomenon in which an image different from the print data is developed, but the potential of the photoconductor drum is uniformly initialized by the initialization charging brush. Not a drum. It is already known that this is generally because the toner on the developing roller did not contribute to the development, that is, the development history remains in the toner corresponding to the non-image forming portion.

Therefore, in the developing roller, the toner having the same density and the same charge amount as the toner remaining undeveloped corresponding to the surrounding non-developed portion is placed in the empty area where the toner used in the development is lost. It is necessary to replenish by the next development.

Since such replenishment is not easy, conventionally, the supply roller rubs the peripheral surface of the developing roller to remove 100% of the toner that has not contributed to the development on the developing roller. Supply fresh toner on the supply roller after 100% removal thereof, ie,
The supply roller rubs the peripheral surface of the developing roller to exchange the residual toner and the fresh toner on the developing roller.

However, a ghost image still occurs. This is because the attraction force between the residual toner not contributing to the development on the developing roller and the surface of the developing roller is affected by the charge amount and the fluidity of the toner on the developing roller which change from moment to moment. It is considered that 100% of the residual toner not contributing to the development on the developing roller cannot be removed over the entire environment only by the physical rubbing force of the roller, so that the ghost image cannot be eliminated.

By the way, since a charge opposite to the charge of the toner remains on the developing roller in the portion where the toner is developed, it is assumed that all the toner on the developing roller is completely replaced with fresh toner. Also, since the electric field of the previously developed portion and the electric field of the undeveloped portion are different due to the above-mentioned residual opposite charge, the electric field history is obtained because the toner amount in the developed portion is different from the toner amount in the non-developed portion. Occurs. This also produces a ghost image. That is, in any case, it is difficult to completely eliminate the ghost image.

In order to solve this problem, a method is known in which a bias voltage is applied to the scooping sheet to remove the charge of the toner on the developing roller. However, even if the electric field history is improved by this configuration, when the charge of the toner is removed from the developing roller, the formation of the toner layer becomes unstable due to a decrease in the charge amount of the toner. The result is that the formed toner layer also becomes thin. Further, in the case where the next development is a development with a particularly high printing rate, it is necessary to leave a toner layer with a reduced charge amount on the developing roller because a sufficient supply of toner cannot keep up.
As a result, the toner is further supplied on the remaining toner layer by the supply roller.

In the case where the chargeability of the toner is reduced under high humidity, there is a case where the effect of removing electricity by applying a voltage from the scooping sheet cannot be exhibited. In other words, since the chargeability of the undeveloped toner layer remaining on the developing roller is reduced, a thick toner layer remains even when voltage is applied from the scooping sheet, and the toner is thicker than usual when toner is supplied from the supply roller. The toner layer passes through the doctor blade.
Also in this case, fogging occurs because the toner layer is thick, that is, the toner cannot be completely charged.

Further, if the printing operation is continued by the conventional developing device, a streak-like image defect may sometimes occur along the image traveling direction in printing a solid image. Since the ground is white on plain paper, it becomes a white streak pattern in the image,
Since the ground is transparent on OHP paper, the image becomes white.
Investigation of the situation where this white streak is likely to occur revealed that it occurs under the following conditions. When the remaining amount of toner in the developing device is low, printing is performed in the OHP paper printing mode (processing speed is about 60% slower than that of the plain paper printing mode).
White streaks are likely to occur in HP paper print mode), and
This is the case when printing in a high-temperature, high-humidity environment.

When the cause of the white streak was investigated, it was found that the contact portion between the doctor blade and the developing roller corresponding to the portion where the white streak occurred, that is, the bent portion (ridge portion) of the tip of the doctor blade and the developing roller Between 0.1 and
It has been discovered that agglomerates of between 0.3 mm and 0.3 mm are interposed and that these aggregates hinder the flow of toner through the doctor blade.

Then, where the agglomerates are present, the toner is not transported to the developing roller or the transport amount is extremely small. Since the electrostatic latent image on the photosensitive drum is not developed, the image on the white streak is not developed. It turned out to be a defect.

The above-mentioned aggregates are not always fixed to the doctor blade from the beginning. Vibration such as opening and closing of the upper cover 13 or removal and reattachment of the image forming unit 40 may easily cause the toner to slip out of the space between the doctor blade and the developing roller, causing the white streak of the formed image to disappear. This can be said to be a state of toner clogging which is caught and clogged between the doctor blade and the developing roller.

As a result of examining the contents of the aggregates, most of the aggregates were large aggregates of hydrophobic silica externally added to the toner, and the fine toner entered and adhered so as to fill the gaps between the silica aggregates. And it turned out to be even larger.

The above-mentioned aggregate is not always contained in the toner from the beginning. For example, as shown by an arrow A in FIG.
It was found that it was formed as the developer roller, doctor blade, and agitator were circulated and moved.

The reason for this is that, due to the physical load applied to the toner from the above-described members, a part of the silica adhering to the toner surface is detached, and they are aggregated by being combined with a part of the fine powder of the toner to form a large particle. It is thought that it becomes.

The above-described conditions under which the toner clogging phenomenon occurs are all conditions under which the formation of the toner layer on the developing roller becomes thin. From this, it is understood that the toner clogging phenomenon is caused by the coagulation of the separated silica and the fine powder toner. When there are many aggregates and the toner layer on the developing roller becomes thin,
It is clear that silica-toner fine powder aggregates are generated due to clogging between the doctor blade and the developing roller.

Based on the above experiments and considerations, in the present invention, in order to solve the above-mentioned problems, by forming a uniform toner layer and maintaining an appropriate charge amount on the toner, fog is prevented. In order to obtain a high-quality image and to maintain a uniform toner layer without toner sticking to the doctor blade until the toner in the developing device runs out, the developing device of the image forming unit 40 shown in FIG. 2
4 is constituted.

Hereinafter, the structure of each part of the developing device 24 according to the present invention will be described in detail. FIG. 3 is an enlarged view showing only a main part of the developing device 24 shown in FIG. 2 according to the present invention. FIG.
As shown in FIG. 3, a developing bias voltage “−250 V” of a bias power supply 47 is applied to the developing roller 25 to develop the electrostatic latent image on the photosensitive drum 18, and the toner is supplied to the supply roller 44. In order to supply 42 to the developing roller 25, a supply bias voltage “−500 V” is applied from another bias power supply 48. The toner 42 carried and conveyed by the developing roller 25 is
5, the layer thickness is regulated and triboelectrically charged.

FIG. 4 is a view schematically showing the principle of supplying the toner 42 to the developing roller 25 of the developing device 24. As shown in the figure, the bias voltage applied to the doctor blade 45 from the variable bias power supply 49 and the developing roller 25
The electric field C is generated between the doctor blade 45 and the developing roller 25 by the bias voltage applied from the constant pressure bias power supply 47 as shown by an arrow in FIG.
Since the toner 42 transported by 5 has a negative charge,
The electric field C receives a force in the direction of arrow D.

The direction in which the electric field C works depends on the direction of the developing roller 2.
5 is determined by the bias voltage a applied to the doctor blade 5 and the bias voltage b applied to the doctor blade. When the bias voltage applied to the developing roller 25 is “−250 V”, when the bias voltage applied to the doctor blade is lower than that (tentatively, "-500V"), the electric field C indicated by the arrow in the figure.
, And the direction of the force received by the toner 42 is the direction of the arrow D as shown in FIG.

In this case, the toner 42 conveyed by the developing roller receives a force that enters between the doctor blade 45 and the developing roller 25, and the toner layer becomes thicker, and the doctor blade 45 and the developing roller 25 Since the chance of frictional charging when passing through the toner decreases, the toner charge amount decreases on average. As a result, an image having a lot of fog is obtained.

Conversely, when the bias voltage applied to the doctor blade 45 is higher than the bias voltage of the developing roller (assuming it is 0 V), the electric field is in the opposite direction to the electric field C shown by the arrow in FIG. Then, the toner 42 that has reached the contact portion with the doctor blade 45 receives a force to be peeled off from the developing roller 25 in the direction opposite to the arrow D in the drawing, so that the toner layer becomes thinner and the toner charge amount becomes average. Become higher. As a result, although the fog is small, the image density is low due to the thin toner layer, or the toner charge is too high, and the toner movement is poor, so that a uniform toner layer is continuously formed. Therefore, when a solid image is printed, a uniform solid image cannot be formed up to the rear end of the image.

From these results, the movement of the toner 42 conveyed to the developing roller 25 when regulated by the doctor blade 45 depends on the bias voltage applied to the developing roller 25 and the bias voltage applied to the doctor blade 45. It can be seen that the difference is controlled by the direction and the magnitude of the electric field.

In the present embodiment, various experiments are performed with the bias voltage of the doctor blade 45 being variable.
For example, a voltage of 100M is applied between the doctor blade 45 and the bias power supply 49 so that the voltage dividing resistors are 1 MΩ respectively.
It is configured so that a resistance of Ω can be inserted. First, 1
When no resistance of 00 MΩ is inserted, the developing roller 25
The resistance between the core metal and the doctor blade 45 greatly varies depending on the humidity of the environment, and drops to about 20 MΩ when left sufficiently in an environment of 30 ° C. and 80%. 25 ℃
If left in a 50% environment, it will be about 1GΩ and 5 ℃
At 10%, it rises to about 8 GΩ.

In this state, when the resistance of 100 MΩ is connected, the bias voltage of the doctor blade 45 under each environment is “−290 V” at 80% at 30 ° C., and “−290 V” at 50% at 25 ° C.
480V ”, at about 5 ℃ 10%“ -497V ”
A low bias voltage can be formed under high humidity, and a high bias voltage can be formed under high humidity. In summary, when the humidity is high, the voltage is changed to a direction close to 0 V (float), and when the humidity is low, the bias voltage or the developing roller 25 (absolute value) is high.
It suffices if a bias voltage close to the above bias voltage can be applied.

That is, the bias power supply 49 of the doctor blade 45 in this embodiment shown in FIGS.
Is configured such that the bias voltage can be changed as described above according to the environmental humidity.

As a result, it is possible to obtain an image having no fogging under high humidity and a good followability of a solid image under low humidity. Further, the toner 4 conveyed to the developing roller 25
Regarding the regulation of the layer thickness of No. 2, it was found that the bending angle and the bending radius of the distal end of the doctor blade 45 had a great influence. As shown in FIG. 8, the toner conveyed by the developing roller is regulated by the doctor blade, and a part of the toner is cut off as shown by an arrow A, and only the toner that has passed through the doctor blade passes through the uniform toner layer. This contributes to development. At this time, if the bending angle of the distal end of the doctor blade is larger than 90 ° as in the related art, that is, an obtuse angle, a force for pushing up the doctor blade by the pressure of the toner acts, and a uniform toner layer cannot be formed. .

FIGS. 5 (a) and 5 (b) show the structure of this embodiment.
FIG. 3 is a diagram illustrating a shape of a distal end of a doctor blade and an arrangement state on a developing roller. In the present embodiment, the bending angle θ of the distal end of the doctor blade 45 is set to an acute angle smaller than 90 ° in consideration of the problem that the bending angle of the distal end of the doctor blade is an obtuse angle larger than 90 degrees as described above.

The bending R at the tip of the doctor blade 45
Is small, it is easy to regulate the toner layer, but the toner 4 entering between the doctor blade 45 and the developing roller 25 is easy to regulate.
2 is excessively loaded, and causes problems such as toner sticking during continuous use. As a result of studying various types of bending R that do not cause such problems and using them in practice, toner sticking was caused. The bending R at the tip of the doctor blade 45 was 0.25 mm or more.

However, when the bending R at the tip of the doctor blade 45 is too large, it has been found that the toner regulating force of the doctor blade 45 is extremely reduced, and a uniform thin layer of toner cannot be formed. When various shapes were prototyped and observed in practice, the upper limit of the bending R at the tip was 0.45 mm.

In the above-described configuration, the doctor blade 45 was formed on the peripheral surface of the developing roller 25 at the contact portion with the developing roller 25 as a result of an experiment in which the arrangement angle was changed at the contact portion with the developing roller 25. 0 ° to 90 with respect to tangent
It has been found that a more uniform thin layer of toner can be formed by arranging at an angle of preferably 15 to 20 degrees.

Based on this, the doctor blade 45 shown in FIGS. 3 to 5 has a tip bending radius R of 0.25 mm to 0.2 mm.
It is arranged at an angle of 15 ° to 20 ° with respect to a tangent line formed on the peripheral surface of the developing roller 25 at the abutting portion.

FIG. 6 (a) is a partially enlarged perspective view of the scooping sheet 46, FIG. 6 (b) is a plan view showing a slightly reduced scale, and FIG. It is an enlarged view of the part shown by the circle E of b). As shown in FIG.
It is composed of a table 46a and a plate 46b. Board 46b
Is a SUS30 having a thickness of 0.1 mm as shown in FIG.
A thin plate of the 4CSP material is provided with a large number of oblique lattice-shaped openings 51 which are subjected to an etching process and inclined at an angle α. The peripheral crosspiece having a width of dmm forming the opening 51 is disposed so as to obliquely cross and contact the longitudinal direction of the developing roller 25 (in FIGS. 2 and 3, the direction perpendicular to the paper surface). The width of the opening 51 along the longitudinal direction of the developing roller 25 is 1.3.
mm.

The toner 42 remaining on the developing roller 25 without being developed is physically separated from the developing roller 25 by the crosspiece constituting the opening 51 of the scooping sheet 46, and passes through the opening 51. It moves to the supply roller 44 side. Thus, all the residual toner on the developing roller 25 is removed. That is, after that, only the fresh toner adheres to the developing roller 25.

In this configuration, the inclination angle α of the opening 51 obliquely intersecting the longitudinal direction of the developing roller 25 is changed so that the opening ratio of the opening does not change and the elastic strength of the plate 46b is maintained. A difference was observed in the toner removing effect on the developing roller 25.

FIG. 7A shows an opening 51 of the scooping sheet 46.
6 is a table showing the relationship between the inclination angle α of the image and the toner removal effect. As shown in FIG. 7A, when the angle α is 0 °, a non-uniform image is generated as a printing result, and the evaluation of the degree of ghost by visual observation of the printed image is “x”. Angle α
Is gradually increased to 15 °, 30 °, and 45 °, the uneven image disappears, and the evaluation of the degree of ghost is “○”. However, when the angle α is further increased to 60 °, a non-uniform image appears again, and the evaluation of the degree of ghost is “x”.

This is because the charged amount and the fluidity of the toner 42 in the developed portion and the undeveloped portion on the developing roller 25 are different. It is considered that the removal rate changes and this is related to the ghost phenomenon. In the present embodiment, the inclination angle α of the opening 51 of the scooping sheet 46 is set to 15 ° to 45 ° based on the results of the above experiment.

FIG. 7B shows an opening 51 of the scooping sheet 46.
4 is a table showing the relationship between the opening ratio of the toner and the toner removing effect. In this example, the opening pitch and the angle α of the beam are kept constant,
Several types of plates 46 with different aperture ratios by changing only the width of the crosspiece
b was prepared and alternately attached to the table 46a, and the occurrence of a ghost image was observed. Then, in this case, too,
As shown in (b), the toner removal rate changed, and even if the aperture ratio was gradually reduced to 93%, 86%, and 79%, the ghost phenomenon occurred up to 79%. The evaluation was visually evaluated as “せ”. The evaluation is “評 価” at 77%, and “x” at 70%.

This is because when the aperture ratio is reduced, the undeveloped toner 42 on the developing roller 25 is hardly peeled off, and the toner 42 moves to the supply roller side through the opening 51. It is considered to be difficult.

Therefore, in the configuration in which the opening 51 is formed and the opening 15 obliquely intersects with the longitudinal direction of the developing roller 25, the crossing between the beam contacting the surface of the developing roller 25 and the longitudinal direction of the developing roller 25 is performed. Angle is 15 ° -4
It can be said that 5 ° and the opening ratio of the opening 51 is preferably 75% or more.

The scooping sheet 46 is supplied with a scooping bias voltage VS from a scooping sheet bias power source 52 as shown in FIG. In this example, normally “−15
0V "is applied to the developing roller 25.
The counter charge remaining on the top is removed.
However, it has been found that when the relative humidity is 30% RH or less, a ghost image caused by the ghost phenomenon due to the counter charge on the developing roller and the above-described toner development history is often observed.

This is because the toner on the developing roller is more charged up under low humidity conditions, so that the counter charge on the developing roller is increased and the mirror image power of the toner on the developing roller is increased. It is considered that this is because it is more difficult to peel off.

In this case, the scooping bias voltage VS is set to "-
460V ", and further down to" -50V "
The potential difference between the developing roller and the scooping sheet is increased, the effect of eliminating the charge of the counter charge on the developing roller is enhanced, and the suction force between the scooping sheet and the developing roller is strengthened, and the physical toner peeling force by the above-mentioned crosspiece is increased, and ghost Images can be eliminated.

As described above, the toner on the developing roller is peeled off, returned to the supply roller side through the opening, and the counter charge on the developing roller is discharged.
The developing roller receives a supply of fresh toner in a state where it is physically and electrically clean, and forms a uniform toner layer. Thereby, the ghost image is eliminated.

The scooping sheet described above is effective for the toner returning to the developing device without contributing to the development. Apart from that, although not particularly shown, the auxiliary doctor is connected to the scooping sheet and the supply roller. It is also effective to provide them between them.

FIG. 7 (c) is a table for examining whether or not the toner clogging phenomenon has occurred in the developing device 24 observed during the test operation of the color image forming apparatus 10. In this test operation, a developing device 24 containing a toner having a configuration described later is mounted on the tandem-type color image forming apparatus 10 shown in FIG. 1, and continuous printing is performed in an atmosphere at a temperature of 28 ° and a relative humidity of 80%. Then, it is examined whether or not a toner clogging phenomenon has occurred from the initial stage when the toner is not used until the toner runs out. In this example, 280 g of the toner was filled in the developing device 24, printing was performed on A4 size paper at a printing rate of 5%, and approximately 6,500 prints were obtained until the toner was exhausted.

[0096] The determination of toner clogging is carried out by printing several solid black sheets on plain paper and OHP paper every 4600 sheets, visually checking for white streaks (toner clogging), and cleaning the toner layer on the developing roller with cellophane. This was visually confirmed by peeling off with a tape to check for transport failure (toner clogging).

The sample toner used was a polyester resin generally used in toners containing a diol such as a bisphenol derivative, a polyhydric alcohol and a dicarboxylic acid such as maleic acid, or a tricarboxylic acid. Carbon black was used as a coloring agent, and negative charge control was performed. Organometallic complexes as agents,
A mixture of low-molecular-weight polypropylene as a fixing release agent is pulverized by a jet mill, classified into an arbitrary particle size distribution, and externally added with hydrophobic fine particles of silica as a fluidizing and charge improving agent using a mixer. It has been processed.
The average particle size of each toner sample is 8.5 μm in weight average.
m. The particle size and the particle size distribution indicate a volume weight distribution and a particle size obtained with a Coulter Counter TA-II (manufactured by Coulter Counter Co.). The CV value was calculated by the following equation.

CV value = (standard deviation of toner distribution / average particle diameter of toner) × 100 The externally added hydrophobic silica has a relatively large particle diameter of 40 nm and a small particle of 8 nm in average particle diameter. The two particles having the same particle size have an external additive amount of 1.4% by weight and a toner amount of 0.1%, respectively.
The treatment was performed so as to be 5% by weight.

The experiment No. shown in FIG. In Nos. 1 to 5, the toner fine powder having a volume percentage of 5 μm or less was 4% or less, and the CV value was 25 or less. In any case, the white streak phenomenon did not occur.

On the other hand, in Experiment No. 6 and 10 are 5% or more of toner fine powder having a volume percentage of 5 μm or less, and CV
The value is 28 or more.
Intense white streak phenomenon occurred around 0 sheets.

Also, in Experiment No. 5 ~ 7% by volume for 7 ~ 9
m is 4% or less, but the CV value is 28 or more in any case. In any case, the toner in the developing device is reduced from 5,000 to 6,000 sheets, and one to several white lines are formed. A phenomenon has occurred.

When the above results are combined, the toner fine powder is 4
% And the CV value was 25 or less, it was found that the white streak phenomenon did not occur. This is because
By removing the fine powder of the toner as much as possible, the aggregate of silica, which is a component of the huge aggregate that causes the toner clogging, and the toner fine particles of the toner fine particles are removed. It is considered that the clogging of the toner that occurs relatively before printing can be prevented as in the example of the developing device in the embodiment.

To keep the CV value low,
This means sharpening the particle size distribution, that is, cutting the coarse powder side. Generally, in the case of non-magnetic one-component development, the toner is developed from a medium particle size when developed, and the fine powder side and the coarse powder side are left in the developing device as the printing proceeds, resulting in a large average particle diameter. Shift toward Even if the fine powder side is regulated as described above, when the ratio of the coarse powder side is large, the average particle diameter in the developing device rapidly increases as the residual toner decreases. As the diameter increases, the fluidity of the toner increases, and the charge amount per unit volume decreases. Accordingly, the slip between the toner increases and the force acting between the toner and the developing roller due to the electrostatic attraction force decreases, so that the amount of toner passing through the doctor blade decreases and the gap between the doctor blade and the developing roller narrows. Therefore, it is considered that a large aggregate that causes toner clogging is likely to be caught between the doctor blade and the developing roller. Therefore, it is considered that toner clogging occurs when the proportion on the coarse powder side increases.

For the above reasons, toner clogging is eliminated by regulating the fine powder side and the CV value of the toner particle size distribution so that the toner fine powder is 4% or less and the CV value is 25 or less.

Lastly, a configuration relating to a decrease in the supply amount of the supply roller over time will be described. In this example, as shown in FIG. 3, a small-diameter roller 53 is disposed above a contact surface between the developing roller 25 and the supply roller 44. The small-diameter roller 53 is formed of a metal rod having a diameter of 3 mm. The small-diameter roller 53 is formed between the developing roller 25 and the supply roller 44 with a gap of about 1 mm so as not to directly contact the development roller 25 and the supply roller 44. To be placed in the valley. A portion having a diameter of about 5 mm is provided at both ends of the metal rod, and the shaft position is fixed so that the metal rod rotates by receiving frictional driving from the developing roller 25 and the supply roller 44. As a result, the supply of the toner from the supply roller 44 to the developing roller 25 is improved, and an image without blurring can be formed.

A humidity sensor is provided inside the developing device, and after detecting 6 hours at a humidity of 70% and 2 hours at 80% by a detection circuit (not shown), the humidity sensor passes through a comparison / arithmetic circuit previously set as described above. Then, the bias voltage of the doctor blade is floated by the bias control circuit, so that good image quality with less fog in a high humidity environment can be obtained.

Instead of installing the humidity sensor inside the developing device, the bias voltage of the doctor blade may be switched based on the detection value of the humidity sensor installed in the image forming apparatus main body.

Further, instead of switching the bias voltage of the doctor blade according to the environmental humidity and the passage of time, the bias voltage of the doctor blade may be switched immediately only by the environmental humidity without measuring the passage of time.

[0109]

As described above in detail, according to the present invention, the bending angle of the tip of the doctor blade is made acute and the bending radius R is formed to be 0.25 mm <R <0.45 mm, so that unnecessary toner is used. Does not penetrate between the doctor blade and the developing roller to form an unnecessarily thick toner layer, thereby forming a toner having a uniform and thin layer thickness, and there is no uneven charging, and therefore, no fogging or blurring High quality images can be formed.

Further, the doctor blade is placed between 0 ° and 90 °, preferably between 15 ° and 90 ° with respect to the tangent line of the contact portion with the developing roller.
Since the toner is arranged at an angle of 20 °, similarly, unnecessary toner does not enter between the doctor blade and the developing roller to form an unnecessarily thick toner layer, so that a toner having a uniform thin layer thickness can be formed. As a result, there is no uneven charging, and therefore, a high-quality image free from fogging and blurring can be formed.

Also, since the bias voltage of the doctor blade is changed in accordance with the environmental humidity, the water content is 0.8%.
Even with the above-mentioned toner, a sufficient charge amount can be given, and a high-quality image with little fogging and blurring can be formed regardless of changes in environmental humidity.

Further, since a large number of fine openings are formed obliquely on the scooping sheet and provided so as to be in sliding contact with the peripheral surface of the developing roller, toner remaining on the developing roller without being involved in the development can be almost easily removed. The entire amount can be collected on the supply roller side, so that fresh toner can be replenished to the entire surface of the developing roller, and a high-quality image that is not affected by the development history can be formed.

[Brief description of the drawings]

FIG. 1 is a side sectional view schematically showing an internal configuration of a color image forming apparatus to which a developing device (developing device) according to an embodiment is mounted.

FIG. 2 is a side sectional view schematically showing a main part of the developing device.

FIG. 3 is an enlarged view showing only a main part of the developing device according to the present invention.

FIG. 4 is a diagram schematically illustrating a principle of supplying toner to a developing roller of a developing device.

FIGS. 5A and 5B are diagrams showing a shape of a distal end of a doctor blade and an arrangement state on a developing roller in an embodiment.

6A is a partially enlarged perspective view of a scooping sheet, FIG. 6B is a plan view showing a slightly reduced scale, and FIG. 6C is an enlarged view of a portion indicated by a circle E in FIG.

7A is a chart showing the relationship between the inclination angle α of the opening of the scooping sheet and the toner removing effect, and FIG. 7B is a chart showing the relationship between the opening ratio of the opening of the scooping sheet and the toner removing effect. ,
FIG. 3C is a table for examining whether or not a toner clogging phenomenon has occurred in the developing device observed during the test operation of the color image forming apparatus.

FIG. 8 is a side sectional view showing a main part of a conventional image forming unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Developing unit 2 Photoreceptor drum 3 Developing roller 4 Toner container 5 Toner 6 Stirrer 7 Supply roller 8 Doctor blade 9 Scooping sheet 10 Color image forming apparatus (Main body device) 11 Openable tray 12 Paper cassette 13 Top cover 14 Discharge tray 15 Belt (Paper Conveying Belt) 16 Drive Roller 17 Follower Roller 18 (18a, 18b, 18c, 18d) Photoconductor Drum 19 Write Head Insertion Groove 21 Cleaner 22 Initializing Charging Brush 23 Write Head 24 Developing Device 25 Developing Roller 26 Supporting Member 27 suction roller 28 standby roller pair 29 paper feed guide path 31 feed roller pair 32 paper feed roller 33 fixing unit 34 paper discharge roller pair 35 switching lever 36 discharge path 37 paper discharge roller pair 38 electrical unit 39 drum unit 40 image forming unit 41 Case 42 Non-magnetic one Component toner 43 Stirring member 44 Supply roller 45 Doctor blade 45-1 Bent end 46 Scooping sheet 47, 48, 49, 52 Bias power supply 51 Opening 53 Small diameter roller

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masafumi Nakahara 2-229 Sakuragaoka, Higashiyamato-shi, Tokyo Casio Computer Co., Ltd. Tokyo Office (72) Inventor Kenji Kihira 2-229 Sakuragaoka, Higashiyamato-shi, Tokyo Casio Computer Inside the Tokyo Office (72) Inventor Yuichiro Iegaki 2-229 Sakuragaoka, Higashiyamato-shi, Tokyo Casio Computer Co., Ltd. (72) Takeo Hirono 2-229 Sakuragaoka, Higashiyamato-shi, Tokyo Casio Computer Co., Ltd. Mitsui Oishi 2-72, Sakuragaoka, Higashiyamato-shi, Tokyo Casio Computer Co., Ltd. Tokyo Office F-term (reference) 2H005 AA08 CB13 EA05 EA07 FA07 2H027 DA11 DA14 DC03 EB04 ED09 2H077 AC04 AD06 AD13 AD23 AD35 AE03 EA14 GA13

Claims (9)

[Claims] 1. A developing device comprising at least a toner carrier for carrying and transporting toner and a toner layer regulating member for regulating the thickness of toner on the toner carrier, wherein the toner layer regulating member is provided. The member is disposed with its tip abutting in a direction opposite to the rotation direction of the toner carrier, the tip has a sharp bend angle, and a bend radius R of 0.2.
A developing device, wherein 5 mm <R <0.45 mm. 2. The toner layer regulating member according to claim 1, wherein the contact portion with the toner carrier is 0 ° to 90 °, preferably 15 ° to 20 ° with respect to a tangent line formed on a peripheral surface of the toner carrier.
The developing device according to claim 1, wherein the developing device is arranged at an angle of °. 3. A predetermined voltage is applied to each of the toner carrier and the toner layer regulating member, and an electric field formed between the toner carrier and the toner layer regulating member is normally developed by the voltage. 3. The developing device according to claim 1, wherein a force is not exerted on the toner charged to a certain polarity, or the toner acts in a direction in which the toner is peeled off from the toner carrier. 4. The developing device according to claim 3, wherein the voltage applied to the toner layer regulating member is set so as to change according to environmental humidity. 5. A developing device comprising a scooping sheet arranged in contact with a developing roller downstream of a developing unit for developing an electrostatic latent image on an electrostatic latent image carrier by a non-magnetic one-component developing method, The scooping sheet is made of a thin plate member having elasticity, and has an opening partitioned by a grid-like bar to physically remove toner remaining on the developing roller without contributing to development, and A developing device, wherein a part or the whole of the crosspiece is disposed so as to obliquely cross and contact a longitudinal direction of the developing roller. 6. The developing device according to claim 5, wherein a predetermined voltage is applied to the scooping sheet to remove a defective potential remaining on the developing roller. 7. The scooping sheet, wherein the opening ratio of the opening is formed to be 75% or more, and the angle at which the cross section that partitions the opening and the longitudinal direction of the developing roller obliquely intersects is 15 ° to 45 °. The developing device according to claim 5, wherein the developing device is arranged at an angle. 8. The apparatus according to claim 1, further comprising variable voltage applying means for applying said predetermined voltage variably according to relative humidity, wherein said variable voltage applying means grounds said predetermined voltage when said relative humidity becomes 30% or less. 7. The developing device according to claim 6, wherein the developing device is varied so as to approach the voltage. 9. A toner containing 0.5% by weight of hydrophobic silica.
A non-magnetic one-component developing method using a 2% by weight externally added non-magnetic toner, wherein the toner has a weight distribution of toner having a particle size of 5 μm or less.
%, Preferably 3% or less, and a CV value of 27 or less, preferably 24 or less.