JP3535681B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a copying machine, for example.
Image forming apparatus such as an electrophotographic type
In particular, the developing means also serves as the cleaning means
The present invention relates to a cleanerless image forming apparatus. [0002] 2. Description of the Related Art Recent copiers and printers
Digitalization with full-color and systematization
Is progressing. For example, a laser beam is scanned and this laser beam is scanned.
-A latent image is formed on the photosensitive drum by turning on and off the light.
Laser beam printer etc. to record the desired image
It is becoming widely known. Typical applications
Is a binary record of characters, figures, etc.
Since the recording does not require halftones, the structure of the printer is simple.
Can be singulated. [0004] Even in such a binary recording system, halftone
There are printers that can form
It is better to use dither method, density pattern method, etc.
Well known. However, as is well known, the dither method
With printers that adopt the degree pattern method, high resolution
I can't get it. Therefore, in recent years, without lowering the high recording density
A method for forming a halftone pixel at each pixel has been proposed.
I have. This means that the laser beam is pulsed (P
WM) halftone formation by modulation
According to this method, a high-resolution and high-gradation image can be obtained.
Can be formed. Here, an image forming apparatus employing the above method
An example of the arrangement will be described with reference to FIG. In FIG. 1, a copy start signal is input.
Then, the photosensitive drum 201 is moved to a predetermined potential by the charger 203.
To be charged. On the other hand,
Original illumination lamp and short focal length lens
Unit 20 with integrated array and CCD sensor
9 scans the document while irradiating it,
The reflected light of the scanning light on the original surface is connected by the short focus lens array.
The image is formed and incident on the CCD sensor. The CCD sensor is a light receiving section, a transfer section, and an output section.
It is composed of The light signal is a charge signal at the light receiving section
And sequentially output in synchronization with the clock pulse in the transfer unit.
The charge signal is converted to a voltage signal at the output
Convert, amplify, lower impedance and output. this
The analog signal obtained in this way is subjected to well-known image processing.
Digital signal and send it to the printer. In the printer section, as shown in FIG.
In the meantime, the ON / OFF light is emitted in response to the above image signal.
Rotating polygon mirror that rotates the light of the body laser element 102 at high speed
Scanning by 104 on the photosensitive drum 1 surface
Then, an electrostatic latent image corresponding to the original image is formed. Further, laser scanning for scanning a laser beam
The unit 100 will be described with reference to FIG. [0010] The laser scanning unit 100
When scanning light, first, based on the input image signal,
The solid-state laser element 10
2 blinks at a predetermined timing. And solid laser
The laser light emitted from the element 102 is collimated
The light is converted into a substantially parallel light beam by the lens system 103, and
Arrow C by the rotating polygon mirror 104 rotating in the direction of the mark b.₀ One
Lens group 105a, 105
b and 105c form a spot-like image on the scanned surface 106
Is done. The photosensitive member is scanned by the laser beam scanning.
On the scanned surface 106 of the drum 201, the exposure for one scan of the image is performed.
A light distribution is formed and each scan plane 106 is moved forward with each scan.
If you scroll by a predetermined amount perpendicular to the scanning direction,
An exposure distribution according to an image signal is obtained on the scanned surface 106.
It is. Next, the electrostatic latent image is transferred to a toner particle and a carrier.
Developing device 2 containing so-called two-component developer having particles
In step 04, the toner image is obtained on the photosensitive drum 1. Here, the developing step will be described.
Generally, the development method is blade for non-magnetic toner.
Coating on the developing sleeve with etc.
Is coated by magnetic force and transported to the photosensitive drum.
Two methods of developing in a non-contact state (one-component non-contact
Development), and further, magnetic carrier particles with respect to the toner particles.
Is transported by magnetic force using a mixture of
And developing in contact with the photosensitive drum (2
Minute contact development) and applying the two-component developer to the photosensitive drum.
With non-contact developing method (two-component non-contact development)
It is roughly divided into four types. In addition, high image quality and high stability
The two-component contact developing method is often used from the surface. FIG. 6 shows a two-component magnet used in the conventional example.
FIG. 2 is a schematic diagram of a developing device 204 for brush development. The developing device 204 has an opening in the developing container 216.
The developing sleeve 211 faces the photosensitive drum 201
A magnet roller is disposed inside the developing sleeve 211.
-12 are fixedly arranged. Also, the developing sleeve 11
A regulating blade 15 for forming a thin layer of the agent is provided.
I have. The developing container 216 is developed by the partition 220.
Chamber R1 and stirring chamber R2.
-13 and 14 are provided. The upper part of the stirring chamber R2
Is provided with a toner storage chamber R3. The developing sleeve 211 is attached to the photosensitive drum 201.
On the other hand, the closest area is about 500 μm.
As shown in FIG.
Rotates and the developer contacts the photosensitive drum 201
It is set so that it can be developed in a state where And now
The peripheral speed ratio of the image sleeve 211 to the photosensitive drum 201 is
Usually, it is set to 1.5 to 2 times. In this manner, the shape on the photosensitive drum 201 is
The formed toner image is transferred to a transfer material by a transfer charger 207.
It is electrostatically transferred on top. Thereafter, the transfer material is transferred to the separation charger 20.
8 and is conveyed to the fixing device 206 by electrostatic separation.
The image is output after being heat-fixed. On the other hand, the photosensitive drum 201 after the transfer of the toner image
Is adhered to the transfer surface by the cleaner 205.
It is used repeatedly for image formation after removal of dye. This configuration is an example, and the charger 20
3 is not a corona charger, but a charging roller or a roller.
Various methods such as the photo-charging device 207 is also a transfer roller
However, basically, as described above, charging, exposure, and current
Image is formed in the process of image, transfer, fixing, cleaning
You. Incidentally, in recent years, such devices have been downsized.
Charging, exposure, development, and transfer as described above.
Each means for carrying out the process of copying, fixing and cleaning
There was a limit just to miniaturization. In addition,
The residual toner is collected by the cleaner 205.
It is preferable that the toner is not emitted from the viewpoint of environmental protection. Therefore, the cleaner 205 is removed.
Then, simultaneous cleaning with development is performed by the developing device 204.
Nana cleanerless devices are also emerging. Simultaneous development
Cleaning means that some toner remains on the photosensitive drum after transfer.
Fogging bias V when developing toner
It is a method of collecting by back. According to this method, the transfer residual toner is collected.
Used after the next process, eliminating waste toner
And no waste toner container is required.
The advantages in terms of source are also large, and the equipment can be significantly reduced in size.
It becomes. [0024] However, the conventional example
Remove the cleaner 205 from a copying machine such as
Attempt to collect at the same time as development
Positive ghost of the previous image occurred in the ram cycle.
In this positive ghost, the transfer residual toner of the previous image is
Could not be collected at
This is a phenomenon that occurs when toner is transferred to a certain place.
To prevent this phenomenon, transfer residual toner should be used during the development process.
100% must be recovered by fog removal bias
Must. Accordingly, an object of the present invention is to provide an image bearing member on an image carrier.
Cleaner-less system that can recover 100% of residual toner
An object of the present invention is to provide an image forming apparatus. [0026] SUMMARY OF THE INVENTION The above objects are attained by the present invention.
This is achieved by an image forming apparatus. In summary, the present invention provides:
An image carrier for carrying a latent image, a non-magnetic toner and a magnetic carrier;
A developing container containing a developer containing
Carrying the developer and transporting the developer to a portion facing the image carrier
Developer carrier, and the latent image on the image carrier is
Contact development with a magnetic brush on the developer carrier
Collecting the transfer residual toner on the image bearing member to the developing container
In the image forming apparatus,The image carrier and the developer carrier
The body is configured to move in opposite directions at the facing portion.
And the peripheral speed of the image carrier is V dr (Mm / se
c), the peripheral speed of the developer carrier is V sl (Mm / se
c) the area where the magnetic brush contacts the image carrier;Said
Moving the image carrierDirection lengthIs L (mm), magnetic brush break
The area is m (mm^Two), The density of the magnetic brush is α (pieces / mm^Two)
And when (| Vsl−Vdr | / | Vdr |) × L × m × α ≧ 7 Where | Vsl−Vdr | is the absolute value of the vector sum of each peripheral speed.
An image forming apparatus characterized by satisfying a value. [0027] [0028] DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described.
Will be described in more detail with reference to the drawings. Embodiment 1 Embodiment 1 of the image forming apparatus according to the present invention is shown in FIG.
Will be described. First, the original G should be copied on the original platen 10.
Set with the side down. Then press the copy button
Starts copying. Original illumination lamp, short focus
Unit with integrated lens array and CCD sensor
9 scans while irradiating the original G,
The light reflected from the original surface of the bright scanning light is
To form an image and enter the CCD sensor. The CCD sensor includes a light receiving section, a transfer section, and an output section.
The optical signal is converted into an electrical signal at the light receiving section.
And sequentially output in synchronization with the clock pulse in the transfer unit.
The charge signal is converted to a voltage signal at the output
Convert, amplify, lower impedance and output. this
The analog signal obtained in this way is subjected to well-known image processing.
Is converted to a digital signal and sent to the printer
You. In the printer section, the image signal
In response, an electrostatic latent image is formed as follows. Exposure
The ram 1 is driven to rotate around a center support shaft at a predetermined peripheral speed.
During the rotation process, the positive or negative polarity is obtained by the charger 3.
After the uniform charging process, the uniform charging surface
As shown in FIG. 5, ON and OFF corresponding to the image signal
The light emitted from the solid-state laser element 103 is rotated at a high speed.
Scanning by the rotating polygon mirror 104
An electrostatic latent image corresponding to the original image is sequentially formed on one side of the ram.
It is formed. The electrostatic latent image is developed by the developing device 4.
A toner image is formed on the photosensitive drum 1. On the photosensitive drum 1
Is transferred to a transfer material by a transfer charger 7.
It is electrostatically transferred on top. Thereafter, the transfer material is transferred to the separation charger 8.
Therefore, the toner is conveyed to the fixing device 6 after being electrostatically separated, and
The image is output. On the other hand, the surface of the photosensitive drum 1 after the transfer of the toner image
Transfer residual toner is left on the
Is collected by the developing device 4 at the next rotation. The configuration of the present embodiment is an example, and
As described above, for example, the charger 3 is replaced with a corona charger.
A charging roller may be used, and the transfer charger 7 is also a transfer roller.
Various methods can be applied.
The image is formed in the charging, exposure, development, transfer,
The transfer residual toner is collected by the developing device. Hereinafter, the image forming step of the present invention is performed.
One embodiment of a developing device will be described with reference to FIG.
I do. In FIG. 2, the inside of the developing container 16 is
The developing chamber (first chamber) R1 and the stirring chamber (second chamber)
R2), and toner is stored above the stirring chamber R2.
A storage chamber R3 is formed, and a toner supply chamber is provided in the toner storage chamber R3.
And a toner (non-magnetic toner) 18. Also, development
The chamber R1 and the stirring chamber R2 have a stirring screw 13,
14 are arranged. The bottom of the toner storage chamber R3
Is provided with a supply port 20, through which it is consumed.
The replenishing toner 18 in an amount corresponding to the collected toner is supplied to the stirring chamber R.
It is dropped and replenished inside 2. On the other hand, in the developing chamber R1 and the stirring chamber R2,
Contains a developer 19. Developer 19 is average
Externally added 1% by weight of titanium oxide with a particle size of 20 nm, pulverized
Non-magnetic toner having an average particle size of 8 μm manufactured by the method
And the saturation magnetization is 205 emu / cm^Three Average particle size of 50μ
m two-component developer comprising magnetic particles (carrier)
You. The mixing ratio of the non-magnetic toner is about 5% by weight.
It was to so. A portion of the developing container 16 close to the photosensitive drum 1
An opening is provided at the upper end of the developing sleeve 1.
It can rotate inside the developer container 16 so that 1 projects outside
It is built in. The developing sleeve 11 is made of a non-magnetic material.
The magnet 12 is fixed inside the magnet 12
Have been. The magnet 12 is located downstream of the developing magnetic pole N1.
Magnetic pole S3 to be placed and a magnetic pole for transporting the developer 19
N2, S2, and S1. The magnet 12 has a developing magnetic pole N1.
In the developing sleeve 11 so as to face the photosensitive drum 1.
Are located. The developing magnetic pole N1 is in contact with the developing sleeve 11
A magnetic field is formed in the vicinity of the developing section between the drum 1 and the magnetic field.
Forms a magnetic brush. In this position,
As the developing sleeve 11 rotates, it is carried in the direction of the arrow.
Developer comes in contact with the photosensitive drum 1 and is on the photosensitive drum 1
Is developed. At this time, the developing sleeve 11
At the position (developing section) close to the photosensitive drum 1
The sleeve 11 and the photosensitive drum 1 are in opposite directions (counter
Direction). The power supply 21 is connected to the developing sleeve 11.
The vibration bias voltage that is obtained by superimposing the DC voltage on the AC voltage
Be added. Latent image dark potential (non-exposed area potential) and bright area potential
(Exposure portion potential) is the maximum value and the maximum value of the oscillation bias potential.
Located between the lows. As a result, the orientation of the developing unit
Alternating alternating electric fields are formed. In this alternating electric field
Causes the toner and carrier to vibrate violently, causing toner to
Latent image by shaking off electrostatic restraint on the probe 11 and carrier
An amount of toner corresponding to the potential adheres to the photosensitive drum 1
You. Difference between maximum value and minimum value of oscillation bias voltage
(Peak-to-peak voltage) is preferably 1 to 5 kV.
The wave number is preferably 1 to 15 kHz. Oscillation bias voltage
As the waveform, a rectangular wave, a sine wave, a triangular wave, or the like can be used. So
Thus, the DC voltage component is the difference between the dark potential and the bright potential of the latent image.
Between dark but darker than the smallest bright potential in absolute value
The closer the value to the position, the higher the power to the dark potential region.
It is preferable for preventing the adhesion of britoner. A blade 1 is provided below the developing sleeve 11.
5 is a predetermined distance from the developing sleeve 11, for example, of the present embodiment.
In this case, they are arranged at intervals of 500 μm. Bray
Non-magnetic material such as aluminum and SUS316
And is fixed to the developing container 16 and is
The thickness of the developer 19 on the block 11 is regulated. The transport screw 13 in the developing chamber R1 is shown in FIG.
Is rotated in the direction indicated by the arrow of FIG.
The developer 19 in the developing chamber R1 is moved to the developing three
The belt 11 is conveyed in the longitudinal direction. The transport screw 14 in the storage room R2 is
By rotation, the toner moves along the longitudinal direction of the developing sleeve 11.
And the toner is supplied to the supply port 2 of the toner storage chamber R3.
It falls freely from 0 into the stirring chamber R2. The pulverized toner of this embodiment has a triboelectric charge amount.
About 2.0 × 10^-2c / kg was used. Here, the amount of triboelectric charge of the toner (the
The method of measuring (developer) will be described with reference to FIG.
You. FIG. 3 shows the measurement of the triboelectric charge of the toner.
Devices are shown. First, try to measure the triboelectric charge
50 to 100 ml volume of two-component developer
And shake it by hand for about 10 to 40 seconds.
Made of metal with a screen 43 of 500 mesh
Approximately 0.5 to 1.5 g is placed in the measuring container 42 of
Do 44. At this time, the entire measuring container 42 is weighed and W
1 (kg). Next, the portion in contact with the measuring container 42 is small.
In the suction machine 41, both of which are insulators, the suction port 47
And adjust the air volume control valve 46 to reduce the pressure of the vacuum gauge 45.
It is 250 mmAq. This state is sufficient, preferably 2
Aspirate for a minute to remove the resin by suction. Potential at this time
The potential of a total 49 is set to V (volt). Here, 48
And its capacity is C (F). Also,
The whole measuring container 42 after suction is weighed and is expressed as W2 (kg).
I do. The triboelectric charge of this toner is calculated as
You. Amount of triboelectric charge of resin (c / kg) = C × V × 10^-3/ (W1-W2) ・ ・ (1) In the present embodiment, there is no cleaner as described above, and
An image forming apparatus configured to collect transfer residual toner during image formation
The photosensitive drum and developing sleeve mentioned in the
Direction and the counter as described in this embodiment.
The developing sleeve and the photosensitive
Varying the peripheral speed of the drum, whether positive ghosts occur
An evaluation was made as to whether or not it was acceptable. In this study, the diameter of the developing sleeve was
16 mm, the photosensitive drum diameter was 30 mm,
The closest distance between the probe and the photosensitive drum was set to 400 μm.
Was. Then, the frictional charge amount of the toner is set to 2.0 × 10^-2c /
kg and the unit area (cm^Two Hit
32 mg of developer [True density of carrier: 5.1 g / c
m^Three , True density of toner: 1.1 g / cm^Three ] The coat
The fog removal bias Vback is fixed at 150 V,
An AC bias of 2 kV and 2 kHz is used as an image bias.
I folded it. If the Vback value is too small, the fog on the white background
If it is too large, carrier adhesion will occur.
Therefore, in this study, the appropriate value of Vback
And fixed at 150V. Table 1 below shows that the photosensitive drum speed (Vdr) is
Table 2 and Table 3 show the results at 50 mm / sec.
The photosensitive drum speed was 200 mm / sec and 30 respectively.
It is a result in the case of 0 mm / sec. Evaluation criteria in the table
When the positive ghost is visible, Y
When the strike was not visually observed, it was evaluated as N. extremely
The case where the lightening occurred was defined as (Y). In the table, the speed of the developing sleeve is
Vsl (mm / sec) and the speed of the photosensitive drum
/ Sec). [0054] [Table 1] [0055] [Table 2] [0056] [Table 3]According to Tables 1, 2, and 3, the forward / developing
In the case of rotation, the peripheral speed ratio between the photosensitive drum and the developing sleeve
When (Vsl / Vd: not described in the table) is 3.5 times or more,
1.5 times or more in case of counter direction and rotation of developing sleeve
Above, when the above conditions are fixed, the positive ghost is visually
I didn't come. As a result of some experiments, it was found that
Sometimes the recoverability depends on the surface properties of the photosensitive drum and various physical properties of the toner
Toner charge), Vback, developing bias, etc.
Under certain conditions, as shown in the following equation (1), the unit time
And a magnetic brush that contacts per unit area on the photosensitive drum.
It was found to be proportional to the area of the sieve. [0059]   (| Vsl−Vdr | / | Vdr |) × L × m × α ≧ 7 (1) Vsl: developing sleeve speed (mm / sec) Vdr: photosensitive drum speed (mm / sec) L: Contact NIP (mm) m: magnetic brush cross-sectional area (mm^Two ) α: Magnetic brush density (number / mm^Two ) Where | Vsl−Vdr | is the absolute value of the vector sum of each peripheral speed.
value Contact per unit area on photosensitive drum
The area of the magnetic brush will be briefly described. Development Three
Speed (magnetic brush speed) Vsl (mm / sec)
The light drum speed is set to Vdr (mm / sec), and the development three
Velocity | Vsl-V
dr | to the area where the magnetic brush and the photosensitive drum are in contact (hereinafter
In this case, it is always constant.
The magnetic brush contacts the photoreceptor with the same thickness
The unit length in the longitudinal direction on the photosensitive drum.
Time t during which the transferred transfer residual toner passes through the contact NIP.
(Sec) indicates that the contact NIP length (the circumferential direction of the photosensitive drum) is L
(Mm), L / Vdr (sec), unit
Magnetic brush contacts per unit area on photosensitive drum at time
The area of the magnetic brush (magnetic brush)
Degree is α (book / mm^Two ) And magnetic brush thickness (cross-sectional area)
Is m × α × | Vsl−Vdr | (this · mm ·
sec). Therefore, the unit area on the photosensitive drum
Magnetic brush that contacts the transfer residual toner
The area of the sheet is expressed as L / Vdr × m × α × | Vsl−Vdr |
It is. In Tables 1, 2 and 3, the contact NIP length L
7 mm, magnetic brush cross section m 0.125 mm^Two , Magnetic
Air brush density α 4 pcs / mm^Two Is the result of
You. From the results in Tables 1, 2 and 3, the residual toner after transfer was
In order to collect 100% in the developing section,
In the case of the forward / sleeve rotation developing method, the photosensitive drum
The rotation of the developing sleeve is about 3.5 times faster than the speed.
Although this is necessary, this is because the developer is liable to
-There is also the problem of scattering. On the other hand, the developing method is
By rotating the developing sleeve into an image,
The peripheral speed difference between the developing sleeve (magnetic brush) and the photosensitive drum
Can be increased, cleaner-less / development
In the case of a simultaneous recovery system, toner scattering and development
In terms of agent deterioration, it is more advantageous than forward development. Also, it depends on the image ratio of the copied image.
However, in general, in counter development, the residual toner after transfer is developed.
When the area is reached, T on the developing sleeve after development
/ C ratio of the developer decreases,
It is easy to collect the toner. As described above, the photosensitive drum and the developing sleeve
And the moving speed of the developing sleeve at Vsl (m
m / sec) and the moving speed of the photosensitive drum is Vdr (mm
/ Sec), and the two-component developer is applied to the developing sleeve.
Length of the contact area [developing section] in the moving direction of the image carrier
Is L [contact NIP] (mm) and the cross-sectional area of the magnetic brush is
m (mm^Two ), The density of the magnetic brush is α (pieces / mm^Two )age
When   (| Vsl−Vdr | / | Vdr |) × L × m × α ≧ 7 (1) Where | Vsl−Vdr | is the absolute value of the vector sum of each peripheral speed.
value Is satisfied, the transfer residual toner is reduced to 100%.
%, And a good image can be obtained. Also,
A two-component developer is used at the opposing portion of the photosensitive drum and the developing sleeve.
The photosensitive drums move in opposite directions (counter direction
Direction) configuration, lower peripheral speed ratio compared to the forward direction
(Speed ratio of developing sleeve to photosensitive drum speed)
Thus, the above expression (1) can be satisfied. this child
Means a long life and low scattering amount
This leads to the provision of a stable developing device. Embodiment 2 In Example 1, the toner particles were formed by a pulverization method as toner particles.
In Example 2, the suspension polymerization was used.
To spherical toner with an average particle size of 6 μm
And externally adding 1% by weight of titanium oxide having an average particle size of 20 nm.
Was used. As a magnetic carrier, the saturation magnetization is
205 emu / cm^Two Magnetic carrier with an average particle size of 35 μm
A. Further, this toner was mixed with a carrier at a weight ratio of 7: 9.
The mixture obtained in 3 was used as a developer. Produced by polymerization method
The external additive is uniform because the toner is almost spherical
To be coated. Therefore, the releasability from the photosensitive drum
Is very good. For example, polymerization with pulverized toner as described above
Transfer efficiency with toner (per unit area transferred on paper
Toner amount / toner amount per unit area on photosensitive drum)
Was compared with 90% of the pulverized toner.
Therefore, when polymerized toner is used, the efficiency is as high as 97%.
Was. When such a polymerized toner is used,
In addition to the extremely small amount of transfer residual toner,
Because there is no cleaner, transfer residual toner is collected during development
In this configuration, recoverability is further improved and positive
Strikes are less likely to occur. The toner is polymerized toner and the photosensitive drum speed
Is 100 mm / sec, conditions other than toner
Is the same as in the study in Table 2 of the embodiment.
Table 4 below shows the results of the evaluation. [0070] [Table 4] The results in Table 4 show that the transfer residual toner is transferred to the developing section.
To achieve 100% recovery, the development method must be
In the case of the development method of leave rotation, the speed of the photosensitive drum
It is necessary to rotate the developing sleeve at least about 3.0 times faster
In the case of the developing method of counter-sleeve rotation,
This indicates that about 1.0 times the speed is required. Implementation
As compared with the pulverized toner in Example 1, the polymerized toner was
By using this, the transfer residual toner can be reduced to 100% at a lower peripheral speed ratio.
% Can be recovered. Therefore, the polymer produced by the polymerization method as in this example was used.
When the used toner is used, the image carrier and the developer support
At the opposing portion, the moving speed of the developer carrying member is set to Vsl (mm
/ Sec), and the moving speed of the image carrier is Vdr (mm / s).
ec), the two-component developer contacts the developer carrier
The length of the area [developing section] in the moving direction of the image carrier is
L [contact NIP] (mm), the cross-sectional area of the magnetic brush is m
(Mm^Two ), The density of the magnetic brush is α (pieces / mm^Two )
When   | Vsl−Vdr | / | Vdr |) × L × m × α ≧ 7 (1) Where | Vsl−Vdr | is the absolute value of the vector sum of each peripheral speed.
value Is satisfied, the transfer residual toner is reduced to 100%.
%, And a good image can be obtained. Also,
A two-component developer is provided at an opposing portion between the image carrier and the developer supporting means.
The image carriers move in opposite directions (counter direction
Direction), the lower circumference compared to the forward direction
Speed ratio (speed of developing sleeve to speed of photosensitive drum)
Ratio), the above expression (1) can be satisfied. This
This means long life and low scattering amount
To provide a highly stable developing device. [0073] As is apparent from the above description, the present invention
According toThe image carrier and the developer carrier are mutually
It is configured to move in the opposite direction and the peripheral speed of the image carrier
To V dr (Mm / sec), the peripheral speed of the developer carrier is V sl
(Mm / sec), the area where the magnetic brush contacts the image carrier
RegionalMoving the image carrierDirection lengthIs L (mm), magnetic brush
M (mm^Two), The density of the magnetic brush is α (book / m
m^Two), (| Vsl−Vdr | / | Vdr |) × L × m × α ≧ 7 Where | Vsl−Vdr | is the absolute value of the vector sum of each peripheral speed.
Value, the transfer residual toner on the image carrier
100% can be collected, and the device can be downsized.
As well as preventing the occurrence of positive ghosts,
An image forming apparatus capable of obtaining an image can be provided.Special
According to the present invention, the positive
In order to prevent ghosting, the developer
The absolute value of the speed can be reduced, so that the deterioration of the developer
Longer life of developing unit by eliminating problems such as developer and developer scattering
Can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a configuration diagram illustrating a two-component developing device used in the image forming apparatus of FIG. FIG. 3 is a schematic diagram showing an apparatus for measuring a triboelectric charge amount of a two-component developer. FIG. 4 is a schematic configuration diagram illustrating an example of a conventional image forming apparatus. FIG. 5 is an explanatory diagram illustrating a laser scanning unit of the image forming apparatus of FIG. 4; 6 is a configuration diagram illustrating a two-component developing device of the image forming apparatus of FIG. [Description of Signs] 1 Photosensitive drum (image carrier) 4 Developing device 11 Developing sleeve (developer carrier)

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-200178 (JP, A) JP-A-7-295389 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/08 507 G03G 15/08 501 G03G 15/09

Claims (1)

(57) [Claim 1] An image carrier for carrying a latent image and a non-magnetic toner
And a developing container containing a developer containing a magnetic carrier,
A pair of the developer holding the developer in the developing container and the image carrier.
A developer carrier conveyed to the opposite portion, and the image carrier
The upper latent image is contacted with a magnetic brush on the developer carrier.
Developing the transfer residual toner on the image carrier while forming an image.
In the image forming apparatus that collects the toner in a container, the image carrier and the developer carrier are mutually opposed at the facing portion.
And the image carrier is moved in the opposite direction.
Is the peripheral speed of V dr (mm / sec),
The speed is V sl (mm / sec).
There the moving direction length of the image bearing member in the region of contact L (m
m), the sectional area of the magnetic brush is m (mm ² ), and the density of the magnetic brush is α (pieces / mm ² ): (| Vsl−Vdr | / | Vdr |) × L × m × α ≧ 7 , | Vsl−Vdr | satisfy the absolute value of the vector sum of each peripheral speed.