JPH034286A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent useless generation of image from unnecessary toner by parallely providing a multiple number of memory erasing means consisting of a multiple number of specified electro conductive artificial fibers along the rotating direction of the photosensitive body bound together, between a transferring means and an electrifying means. CONSTITUTION:A drum shaped photosensitive body 15 is provided in a photo graphic processing unit 3 of the device main body 1. A memory erasing means 20 consisting of an electrifying means 16, a laser exposing unit 17, a developing means 18, a transferring means 19, and a brush member and a preexposure means 21 are sequencially provided in the periphery of the photosensitive body 15 along the direction of its rotation. The memory eliminating means 20 is provided with ruggedness on its periphery and is constituted from a multiple number of electro conductive artificial fibers bound together whose volume resistance is specified to 10<2> to 10<7> OMEGA.cm. Thus, useless generation of image from untransferred toner of preceding image forming cycle can be prevented and a good image can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an image forming apparatus that uses electrophotography, and particularly to an image forming apparatus that includes a step of cleaning at the same time as development.

(Prior Art) In recent years, this type of image forming apparatus uses a developing process in which colored powder (toner) is attached to an electrostatic latent image formed on a photoreceptor using a developing means to form a toner image. Thereafter, the toner image on the photoreceptor is transferred to a recording medium such as plain paper, while the untransferred toner on the photoreceptor after transfer is developed and exposed to light by the developing means in the next image forming cycle. Image forming devices that are designed to be removed (cleaned) from the body have been developed.

This type of image forming apparatus uses a cleaning method that performs cleaning at the same time as development, so there is no need for a dedicated cleaner, and it is possible to reduce the diameter of the image carrier, and furthermore, the entire apparatus can be made smaller, lower in cost, and easier to maintain. It has the great advantage of being able to improve performance, and its practical application is strongly desired.

(Problems to be Solved by the Invention) However, in this type of apparatus, if toner remains on the photoconductor without being transferred during the transfer process in the previous image forming cycle, the toner remains on the photoconductor in the next cycle. Since the charging and exposure process for the toner is performed through this untransferred toner, uneven charging or exposure occurs, resulting in the production of unnecessary images, which is a serious problem.

The present invention has been made based on the above-mentioned circumstances, and an object thereof is to perform a cleaning process simultaneously with development in an image forming apparatus including an image bearing member and a memory removal/brush. An object of the present invention is to provide an image forming apparatus that can prevent the generation of unnecessary images due to transferred toner, obtain good images, and further reduce the size, cost, and maintainability of the entire apparatus. It is.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention uses a large number of conductive artificial fibers having an uneven shape around the periphery and having a volume resistivity of 10 to 107Ω・C12. A plurality of bundled memory removing means are provided along the rotational direction of the photoreceptor between a transfer means for transferring a visible image on the photoreceptor and a charging means for charging the photoreceptor.

(Function) That is, the present invention uses the above means to remove untransferred excess developer remaining on the photoreceptor after the transfer process after the transfer process by the transfer unit and before the charging process of the next image forming cycle by the charging unit. The adhesion of the developing material to the photoreceptor is leveled by removing it from the photoreceptor and returning it again.
This prevents residual developer material after transfer from affecting the charging and exposure process.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows the external appearance of an electrophotographic image forming apparatus using a semiconductor laser, and FIG. 3 shows its internal configuration. This image forming apparatus (laser printer) is connected to a host system (not shown), which is an external output device such as an electronic computer or a word processor, via a transmission controller such as an interface circuit. When a print start signal is received from the host system, an image recording operation is started, and the image is recorded on paper as a transfer material and output.

This image forming apparatus has the following configuration.

That is, numeral 1 in the figure is a main body of the apparatus, and a main control board 2 is disposed in the center of the main body 1 of the apparatus. and,
An electrophotographic process unit 3 for forming images is arranged behind the main control board 2 (toward the right side in the state shown in FIG. 3), and a plurality of control boards for adding functions are located at the lower front. A control board accommodating section 5 for accommodating a plurality of 4 sheets, and a paper ejecting section 6 are formed at the upper front part.

Further, a lower portion inside the apparatus main body 1 is a cassette accommodating section 8 that accommodates a paper feed cassette 7.

As shown in FIG. 2, the paper ejection section 6 consists of a recess formed on the front upper surface of the main body 1 of the apparatus, and the front edge of the paper ejection section 6 is folded over the paper ejection section 6 or has a recess as shown in the figure. A rotatable paper discharge tray 9 that can be unfolded is provided. Furthermore, a notch 9a is formed in the center of the front end of the paper ejection tray 9, and a rotatable U-shaped auxiliary ejection that can be accommodated in the notch 9a or unfolded as shown in the figure. A tray 10 is provided. The size of the paper discharge section 6 can be adjusted according to the size of the paper P to be discharged.

Further, a control panel 11 is disposed on the upper surface of the left frame portion 1a of the apparatus main body located on the left side of the paper ejection section 6, and a manual feed tray 1 is disposed on the rear side of the apparatus main body 1.
2 is installed.

Next, the electrophotographic process unit 3, which performs electrophotographic processes such as charging, exposure, development, transfer, peeling, cleaning, and fixing, will be described with reference to FIGS. 3 and 4.

A drum-mounted photoreceptor 15 serving as an image carrier is disposed approximately in the center of the unit accommodating portion, and this photoreceptor 1
5, a charging means 16 made of a scorotron and an exposure section 17a1 of a laser exposure unit 17 as an exposure means (electrostatic latent image forming means) are arranged along the rotational direction to perform the development process and the cleaning process at the same time. A magnetic brush type developing means 18 and a transfer means 19 consisting of a scorotron
, a memory removing means 20 consisting of a brush member, and a pre-exposure means 21 are arranged in this order.

Also, inside the apparatus main body 1, paper P fed from the paper feed force set door via the paper feed means 22 and the manual feed tray 12 are stored.
A paper conveyance section 24 is formed to guide the paper P manually fed from the photoreceptor 15 and the transfer means 19 to the paper discharge section 6 provided on the top side of the apparatus main body 1 via the image transfer section 23. has been done.

Furthermore, an aligning roller pair 25 and a transport roller pair 26 are arranged on the upstream side of the image transfer section 23 of the paper transport path 24, and a fixing unit 27 and a paper ejection roller pair 28 are arranged on the downstream side.

Further, a pair of conveying rollers 26 is provided. Note that 13 is an aligning switch.

When a printing start signal is received from the host system, the drum-shaped photoreceptor 15 rotates, and the photoreceptor 15 is charged by the charging means 16. Next, the laser beam a modulated in response to the dot image data from the host system is operated to expose the photoreceptor 15 using the laser exposure unit 17 including the polygon mirror scanner 30, and an image signal is formed on the photoreceptor 15. A corresponding electrostatic latent image is formed.

This electrostatic latent image on the photoreceptor 15 is developed and visualized by the toner t in the magnetic brush D' of the developing means 18.

On the other hand, in synchronization with this toner image forming operation, the paper P taken out from the paper feed cassette 7 or manually fed from the manual tray 12 is fed through a pair of aligning rollers 25 and placed on the photoreceptor 15 in advance. The toner image formed on the paper P is transferred to the paper P by the action of the transfer means 19. Then, the paper P passes through the paper transport path 24 and is sent to the fixing unit 27. This fixing unit 27 includes a heater lamp 4
0 and this heat roller 4
1, the pressure roller 42 is pressed against the roller 4.
1 and 42, the toner image is transferred to the paper P.
is melted and fixed. After this, the paper ejection roller pair 28
The paper is discharged to the paper discharge section 6 via the paper discharge section 6.

Note that after the toner image is transferred onto the paper P, the residual toner remaining on the photoreceptor 15 is removed by the memory removing means 7 consisting of a conductive brush, and the memory is removed in the next developing step as described above. will be collected.

In addition, in the present invention, in order to simplify the process of conventional electrophotography, a reversal development method is adopted in which the exposed portion is developed, and a method is adopted in which the residual toner t after transfer is removed at the same time as the development. Adopted. At this time, changes in the surface potential of the photoreceptor 15 and the state of the toner t on the photoreceptor 15 are changed as shown in FIG.

That is, the charging means 16 charges the photoreceptor 2 to -5
It is charged to 00V [see (A) in FIG. 5]. At this time, the toner t on the photoreceptor 15 that was not completely transferred in the previous process is also charged at the same time.

At this time, it has been found from experimental results that even if the toner t... is removed with a urethane blade or the like, the surface potential is maintained at 80 to 90% or more.

Next, the photoreceptor 15 receives the laser beam a which is modulated in response to the dot image data from the host system and scanned by the laser exposure unit 17 as described above.
The surface potential is attenuated and an electrostatic latent image is formed.
)reference]. The surface potential of the exposed area at this time is -50V (room temperature). Here, the photoreceptor 15, the charging means 16, and the laser exposure unit 17 are designed as follows.

The photoreceptor 15 uses an OPC (organic photoconductor) photoreceptor, and the ji! As shown in Fig. 6, a charge generation layer 51 is placed on a double-sided aluminum cylinder 50 (thickness 0.8 mm) with an outer diameter of 30 am.
, charge transport layer 52 are applied in this order.

The charge generation layer 51 is made of γ-type raphthalocyanine (manufactured by Toyo Ink) and butyral resin in a weight ratio of 1:1 and a thickness of 0.1 μm.
It was coated on. The charge transport layer 52 is made of 9-ethylcarbazole-3-carboxaldehyde methylhydrofusone (E CMP) [manufactured by Kenu Pharmaceutical] and polyarylate (U-100) C manufactured by Unitika] with an It ratio of 0.65. It was applied to a thickness of 17 μm. This charge transport layer 52 is transparent to visible light and semiconductor lasers, and because it is located above the charge generation layer 52, even if toner particles t of 30 μm or less are present on the surface, as shown in FIG. When the photoreceptor 15 is exposed to light 55, due to the diffracted light 56 and the reflected and scattered light 57 within the transport layer 52, there is almost no shadow of the toner particles t on the charge generation layer 51, or there is no problem in practical use. This can only be achieved through thinness. However, when the diameter of the toner particles t exceeds 30 μm, image defects occur as white spots on a solid black surface. The transport layer 52 may be made of any material as long as it is transparent to the exposure light source and has a carrier transport function, such as a polycarbonate resin in which a pyrazoline derivative is dispersed, or an acrylic resin in which an oxadiazole derivative or an oxazole derivative is dispersed. Alternatively, a triphenylmethane derivative dispersed in polycarbonate resin may be used. Further, if the thickness is not greater than the average particle diameter of the toner t, it will cause image defects. Furthermore, as shown in FIG. 8, the thickness is preferably 30 μm or less in view of residual potential characteristics. The photoreceptor 15 basically has a charge transport layer 5 on top of the charge generation layer 51.
2, as shown in FIG. 9, the generation layer 51 and the substrate 58
A protective layer 60 or the like may be provided on the surface of the undercoat layer 59 and the transport layer 52 in between. The photoreceptor 15 used outside this implementation has a photosensitivity of half-decreased exposure amount of 6.2erg/ctx2 (jff
(see 1O diagram). Here, the appropriate value of the amount of laser light is determined based on the following grounds.

This process does not use a dedicated cleaner or an independent process for cleaning, and performs electrostatic cleaning at the same time as development, so that image exposure is performed from above the transfer residual toner t existing on the photoreceptor 15. Therefore, in some cases, a portion where transfer residual toner t exists may be exposed.

Normally, the photoreceptor 1 is used for areas where there is no remaining transfer toner t.
Exposure amount to half the surface potential of 5 (6.2e in this example)
rg /cm2) (1) An exposure amount of about 3 to 4 times is sufficient for the latent image potential of the image, but (
For example, in FIG. 10, 24.8 erg/cm"'), the toner t acts as a filter for a portion where several pieces of untransferred toner are grouped together, and the photoreceptor 15 is underexposed in that portion, resulting in memory loss. occurs, resulting in a defective image.

In other words, if the exposure amount is less than 4 times, a one-dot wide black and white bare line as shown in (a) in Figure 11B or a checkerboard pattern created by exposing every other dot as shown in (a) in Figure 11A In the case of a pattern such as that shown in (b) of FIGS. 11A and B, the portion to be developed is chipped according to the pattern of the transferred residual toner t... on the photoreceptor 15, and the chipped portion of the image is As shown by (c) in FIGS. 11A and 11H, it becomes visible as a negative pattern.

For this reason, the present invention is designed to reliably remove the residual toner t after transfer, as will be described later.

Next, the main electrophotographic process components mentioned above will be explained in detail.

First, the charging means 3 is composed of a scorotron as shown in FIGS. 12 to 15. A corona wire 71 with a diameter of 60 μm is stretched inside a shield case 70, and the surface of the corona wire 71 is made of white tungsten to prevent uneven generation of negative corona.

The corona wire 71 is fixed to a metal fitting 74 to which a power supply bottle 73 serving as a charging means power supply section is screwed. The power supply pin 73 and metal fittings 74 are the power supply terminal 75
Fixed inside.

On the other hand, the other end of the corona wire 71 is connected to the tension spring 7.
2 to a plastic hook 76 and fixed to a terminal 77. Above terminal 75.7
7 are covered with terminal bars 78 and 79, respectively, so that the parts to which high pressure is applied are not exposed.

On the other hand, the shield case 70 is made of stainless steel with a thickness of 0.3 ms, and has a mesh on the side facing the photoreceptor 15, as shown in FIG. 14, and has a simple structure that serves as the grid 70a of the scorotron charger. However, since the grid 70a is integrated with the side cases 70b and 70c, sufficient precision such as its flatness can be maintained without using any special parts.

Furthermore, since the same bias voltage is applied to both side cases 70b and 70c when corona discharge occurs (described later), the corona current flowing through both side cases 70b and 70c is also reduced, resulting in a charger with good current effect.

Further, the shield case 70 is connected to the anode of a 560V Zener diode 82 (see Figure M18), and is connected to a charger guide 83 (see Figure 18) through the cathode of the Zener diode 82. On the other hand, the charger guide 83 is coupled to the ground terminal of the main body.

Therefore, the corona wire 71 is connected to the high voltage transformer (
When a higher voltage (-5 kv) (not shown) is applied through the power supply bin 73, corona discharge occurs in the shield case 70, and current flows through the shield case 70. However, due to the rectifying characteristics of the Zener diode 82, the shield case The potential at 70 rises to -56 Qv and remains constant.

Therefore, since the grid 70a naturally becomes -560V, the surface potential of the photoreceptor 15 located 2IIIM from the grid 7'Oa is kept constant at -500V, which is slightly lower than the potential of the grid 70a. In the figure, when the charger 17 is integrated into the process cartridge 105 (see FIG. 1), which will be described later, the engaged portion 82 (see FIGS. 19 and 20) formed in the process cartridge 105 is This is an engaging portion that engages.

As shown in the fourth factor and FIG. 16, the laser exposure unit] 7 includes a semiconductor laser oscillator (not shown), a polygon scanner 32 consisting of a polygon mirror 30 and a mirror motor 31, an fθ lens 33. Correction lens 3
4. It is composed of reflection mirrors 35, 36, etc. for scanning the scanned laser beam a to a predetermined position. The lower side of the laser exposure unit 17, that is, the upper and lower sides of the cassette storage section 8 are open, and the paper feed cassette 7 can be pulled out forward (in the direction of the arrow in FIG. 3). It has a structure that allows it to be taken out downward in a closed state (see Fig. 16).

Further, as described above, the developing means 18 employs a reversal developing method and a method in which the residual toner t after transfer is removed at the same time as development in order to simplify the electrophotographic process. There is. As shown in detail in FIGS. 4 and 17, this developing means 18 includes a photoreceptor 15 and a developing roller 92 provided in a casing 91 having a developer storage section 90. , developer storage section 9
A two-component developer consisting of toner (colored powder) t and carrier (magnetic powder) C is housed in the container 0.

Further, the sliding contact portion of the developer magnetic brush D' formed on the surface of the developing roller 92 with the photoreceptor 15, that is, the developing position 9
A doctor 94 for regulating the thickness of the developer magnetic brush D' is provided upstream of the photoconductor 3 in the rotational direction of the photoreceptor 15. Further, the developer storage section 90 includes a first
．． Second developer stirring bodies 95 and 96 are accommodated.

Note that the developing means 18 is equipped with a toner replenishing device (not shown) so as to appropriately replenish the developer accommodating portion 90 with toner t.

Further, the developing roller 92 is a magnetic roll 1 having three magnetic pole parts 100, 101, and 102 as shown in FIG.
03, and a non-magnetic sleeve 104 that is fitted onto the magnetic roll 103 and rotates clockwise in the figure. The three magnetic pole parts 100, 101 of the magnetic roll 103,
102, the magnetic pole portion 101 facing the development position 93 is N
The other magnetic pole parts 100 and 102 are S poles. Also, the angle θ between the magnetic pole part 100 and the magnetic pole part 101
1 is set to 150°, and the angle θ2 between the magnetic portion 101 and the magnetic pole portion 1°2 is set to 120°.

The electrostatic charge on the photoreceptor 15 is caused by the potential difference between the mechanical scraping force caused by magnetic brush development using a two-component developer, the charging potential caused by reversal development, and the development bias applied to the magnetic brush D'. At the same time as the latent image is developed, residual toner t is collected mechanically and electrically.

Furthermore, this developing means 18 includes images shown in FIG. j@1, FIG.
As shown in FIGS. 18 and 19, a photoreceptor 15, a charging means 16, a memory removing means 20, etc. are integrated into a process cartridge 105. It can be inserted into and taken out of the device main body 1 via an insertion/removal handle 110 (see FIGS. 18 and 19). Also,
On the other end side, a charging means power supply section 1 consisting of a developing bias power supply section 111, a memory removing means power supply section 112, and a power supply bottle 73 is provided.
13 is provided protrudingly, and this process cartridge 10
5 into a predetermined position within the apparatus body 1, these power supply parts 111, 112, and 113 are inserted into a power supply connector provided within the apparatus body 1.

Further, a foldable handle 115 for carrying is provided on the top side of the process cartridge 105, and a cleaning brush 116 for cleaning the lower roller 25a of the aligning roller pair 25 is attached. Furthermore, as shown in FIGS. 1 and 20, on the other end side of the developing means 18, the developing sleeve 104, the first. A gear group 122 that is connected to the second developer stirring body 95, 96, a winding shaft 121 (see FIG. 17) for winding up the photoreceptor protection sheet 120, etc., and that interlocks with each other.
has been set up. And gear 122a
meshes with a drive gear (not shown) provided on the device main body 1 side, and by driving this gear 122a, each of the above-mentioned rotating members is rotationally driven in a predetermined direction at a predetermined speed. . Note that the photoreceptor protection sheet 120 wound around the winding shaft 120 is housed in a guide tube 124 surrounding the winding shaft 120, so that the end portion does not protrude to the outside.

Note that 125 shown in FIG. 20 is a positioning groove for the charging means 19.

Further, 126 shown in FIG. 18 is a process cartridge 1.
05 is a rod for pressing the presence detection switch (not shown), 127 is a toner replenishment port shutter that opens when a toner replenishment hopper (not shown) is attached, and 128 is a shutter spring. Further, 129 is a pin for fixing the photosensitive drum.

As shown in FIGS. 18 and 21, an auto-toner sensor ring 140 consisting of a metal-plated cap is attached to one end of the photoreceptor 15, and the developer concentration can be detected at this portion. It has become. As shown in FIG. 22, this auto toner sensor ring 140 is connected to a doctor blade 94 via a conductive leaf spring 141 made of phosphor bronze or the like.
Furthermore, it is connected to the developing sleeve 104 via a conductive leaf spring 142, so that the auto-toner sensor ring 140, the doctor blade 94, and the developing sleeve 104 are at the same potential. In other words, power can be supplied to the auto toner sensor ring 140 without using a dedicated power supply means.

Further, the photoreceptor 1 provided with the auto toner ring 140
5, a flange 145 equipped with a leaf spring 143 and a bush 144 is attached to the other end as shown in FIG. A photoreceptor drive shaft 146 provided on the apparatus main body 1 side is inserted into the photoreceptor drive shaft 145a. Then, the locking tongue portions 143a of the leaf springs 143 engage with the engaged portions (not shown) of the photoreceptor drive shaft 146, so that the photoreceptor drive shaft 146
The driving force is transmitted to the photoreceptor 15.

Further, the transfer means 19 is composed of a scorotron as shown in FIGS. 23 to 26.

A corona wire 151 is stretched inside a shield case 150, and one end of this corona wire 151 is connected to the 23rd
As shown in the figure and FIG. 24, it is connected to a metal fitting 153 screwed to the power supply terminal 152, and the other end is connected to the shaft 155 of the power supply terminal 154 via a tension spring 156 as shown in FIG. . Further, the portion of the shield case 150 facing the photoreceptor 15 is formed into a mesh as shown in FIG.
It constitutes a.

23 and 2 on the power supply terminal 152 side.
As shown in FIG. 6, a grid voltage power supply section 157 and a wire high voltage power supply section 158 are provided.

Next, the memory removing means 20 will be explained.

The memory removing means 20 includes a brush member 160 and a holding member 204 that holds the brush member 160.

The brush member 160 is made of rayon, nylon, acrylic,
It is a bundle of conductive artificial fibers whose main component is resin such as polyester, carbonized carbon particles, metal powder, phenol resin, etc., or conductive materials such as stainless steel fibers. be. This artificial fiber is made by, for example, dispersing an appropriate amount of carbon particles in the resin liquid and extracting it from a nozzle-shaped extraction port. The volume resistivity of the artificial fiber can be freely selected by changing the amount of carbon particles dispersed. Further, the thickness and cross-sectional shape of the artificial fiber can be changed as appropriate depending on the diameter and shape of the extraction port of the nozzle.

It is desirable that the artificial fiber used as the brush member 102 of the present invention has a volume resistivity of 102 to 107 Ωcm. If the deposition resistance is less than 102 Ωam, when a voltage is applied to the brush member 102 to electrostatically attract residual toner as described later, a discharge phenomenon occurs between the brush member 102 and the photoreceptor, and the photoreceptor layer of the photoreceptor is damaged. Problems such as destruction arise. In addition, if the volume resistance is greater than 107 Ωcm, even if a voltage is applied to the brush member 160, the untransferred toner on the photoreceptor cannot be electrostatically attracted, and the untransferred toner directly moves to the brush member 160. Since it passes through, the effects of the brush member 160, which will be described later, cannot be obtained.

The artificial fiber used as the brush member 160 of the present invention has a cross-sectional shape as shown in FIG. That is, the artificial fiber has irregularities 160a on its peripheral surface, and these irregularities are substantially continuous in the length direction of the artificial fiber. Therefore, the artificial fiber used in the brush member 160 of the present invention has a large surface area and maintains linear orientation in the length direction. For this purpose, the brush member 160 is exposed to light, and the body 15 is exposed to light.
When brought into contact with the brush member 102, the brush member 102 can come into contact with more residual toner on the photoreceptor 15, and the brush member 102 is not bent, so that the action and effect of the brush member 160, which will be described later, can be improved. It can be used for a long time and can be used for a long time.

Moreover, the thickness of the artificial fiber is preferably 1 to 50 deniers. If the denier is less than 1 denier, the artificial fibers may break or easily fall off from the holding member 204, making it impossible to withstand long-term use as the brush member 160 of the present invention. If the denier is larger than 50 denier, even if the artificial fibers are brought into contact with the photoreceptor, the bundle of the artificial fibers will be coarse, resulting in problems such as untransferred toner passing through without making sufficient contact with the brush member 160. , it is not possible to obtain the effects of the brush member 160, which will be described later.

The holding member 204 includes a holding fitting 162 and a backing member 161.
and an auxiliary sheet metal 210. The holding fitting 162 is a plate made of a conductive metal, for example, an aluminum alloy.
One end side is bent in advance to have an abbreviated cross-sectional shape, and extends long in the axial direction of the photoreceptor.

Then, by taking into account the thickness a of the brush member 160 from the central part of the holding fitting 162 in the lateral direction, the plate material is bent around the part displaced toward the other end, and the base of the brush member 160 is inserted between the parts. supports the brush member 160. The brush member 160 is bent into an abbreviated shape between one end and the other end of the holding fitting 162. At this time, if the thickness a is smaller than the thickness a of the brush member 160, there is a risk that the brush member 160 may be cut off when the brush member 160 is sandwiched between plates, so it is preferable that the thickness a be larger.

Further, the relationship between the thickness of the brush member 160 and the thickness C of the holding fitting 162 in a bent state is that the thickness a is 0.5 to 2.
mm, the thickness C is 2. It is desirable that the thickness be about 5 to 4 mm, and if it is outside this range, there will be a problem that the brush member 160 will be easily cut or removed when the plate material is bent.

Note that in order to prevent the brush member 160 from coming off, a conductive adhesive may be poured between the brush member 160 and the plate material for reinforcement.

The backing member 161 is provided along the surface of the brush member 160 opposite to the surface that contacts the photoreceptor 15, and is for pressing the free end side of the brush member 160 against the photoreceptor. The length of this backing member in the transverse direction is the length of the brush member 1
By making the length longer than the free end side of the brush member 60, there is also an effect of preventing the brush member 160 from having bending curls. Furthermore, by making the length of the brush member 160 in the longitudinal direction longer than that of the brush member 102, it is possible to obtain the effect of preventing the toner once attracted by the brush member from scattering.

Further, by making the backing member a particularly elastic or flexible resin member such as polyester resin, damage to the photoreceptor can be prevented even if the backing member comes into contact with the photoreceptor.

The auxiliary sheet metal 210 is provided in contact with the backing member on the side opposite to the photoconductor, and is provided in contact with the backing member 161 and the brush member 160.
It is intended to reinforce the

In the present embodiment, the auxiliary sheet metal 210 and the backing member 161 are constructed as separate members, but it is also possible for a - number of members to serve as both. In this embodiment, the brush 160 is made of rayon impregnated with carbon to give a specific resistance of 106 Ω·Cm and made into fibers with a thickness of 6D (denier), which are made into bundles of 100 fibers at a density of 82 bundles/inch. It is constructed by making it into a satin weave and removing two layers of weft threads. Further, the brush 160 has a backing member 161 made of a polyester film having a thickness t (about 0.1 ma) on one side, as shown in FIGS.
It is attached to the holding fitting 162 in a state where it protrudes by 5 (approximately 1.0 ■I). Then, θ with respect to the photoreceptor 15
(15°) installation is 31° from the tip of the brush 160 at the corner.
It is installed upstream of the charging means 16 so that the brush surfaces are in contact with each other at the position.

A preferred shape of the memory removal means 20 is a fixed brush shape. That is, when the brush is rotated or moved from side to side, the toner not only scatters, but the rotary type also becomes larger and requires a drive system, resulting in higher costs.

Next, the principles, conditions, etc. of simultaneous development cleaning, transfer, image removal, etc. will be explained, including experimental data.

Main cleaning and simultaneous development process (Cleaning
&Developing Process: CDP
) is important in that it is performed using reversal development. This is because the polarity of the toner and the polarity of the charging are the same, so the polarity of the toner is not reversed by the charging means 3.

On the other hand, as shown in FIG. 34, when a cleaning process is performed using regular development, the following occurs.

In this case, if a negatively charged photoreceptor is used, the polarity of the toner will be positive, but in the charging step, the toner remaining after transfer becomes negative, which is the opposite polarity. Exposure step 3
In FIG. 4B, a portion corresponding to the background (white background) is irradiated with light, but the light usually goes around under the toner, and the potential under the toner in the background portion is also attenuated.

Next, when the unexposed areas are developed using toner of positive polarity, the residual toner transferred on the unexposed areas of the photoreceptor is electrostatically removed, and the pattern to be developed is removed in a negative form, resulting in black negatives and memory. The image becomes defective.

In addition, the negative toner remaining after transfer in the exposed area is not sucked into the developing device, so it remains on the photoreceptor. Furthermore, in some cases, development may occur in which positive polarity toner in the developer is attracted.

In the transfer step (D), the remaining toner on the exposed area remains on the photoconductor without being transferred because it has the same polarity as the transfer charger. Therefore, each time a process cycle is repeated, the amount of untransferred toner on the photoreceptor increases. Further, since the positive polarity toner attracted by the residual toner is transferred, an image obtained before one revolution of the photoreceptor drum appears on the white background portion of the transferred image (white positive memory). In other words, in the regular development method, each time a process cycle is repeated, the amount of untransferred toner on the photoreceptor increases, and the occurrence of black negative memory and white positive memory increases. In other words, this is the reason why simultaneous development with cleaning is extremely difficult in regular development, but easy in reversal development.

Further, in this method, since the photoreceptor is cleaned by the developing device, paper waste adhering to the photoreceptor is taken into the developing device. Therefore, in order to form a thin layer of developer on the developing sleeve, there are magnetic component methods in which the developing sleeve and doctor blade must be made as narrow as several hundred microns, and non-magnetic component methods in which the doctor blade slides into contact with the sleeve. In this method, when printing a large number of sheets, paper waste gets trapped between the doctor blade and the developing sleeve, making it impossible to form a uniform developer layer on the sleeve, which tends to cause image defects.

(However, it goes without saying that even a single-component developer can be sufficiently implemented in terms of image quality and frequency of use.) On the other hand, two-component developing method does not have such problems, so even if more than 50,000 sheets are printed, image defects may occur. did not occur at all. In other words, the two-component developing method requires a longer maintenance period for the developing device, and is preferable to this method.

However, in this CDP method, certain process conditions are required to obtain high quality images. FIG. 35 is an explanatory diagram of the contents (terms) used here, in which the photoreceptor 15 is connected to the charging means 16.
The potential when the developing position 93 reaches the developing position 93 while being charged and unexposed is called the charging potential vo, and the attenuated potential after being exposed by the exposure means 17 is applied to the developing roller 94 of the developing means 18 with a post-exposure potential V er%. The potential is called the development bias vb, and the difference between the post-exposure potential Ver and the development bias vb is the development potential Vb -Vb-Ver%Charging potential Vo and the development bias v
The difference between VCL and b is called the cleaning potential VCL-VO-Vb.

In this embodiment, a negatively charged OPC was used for the photoreceptor 15, but positive charging types were also taken into consideration, and OPCs were used as vb, ver, and vb-.
We will discuss Ver and Vo-Vb as absolute values.

In the first quadrant of FIG. 36, the horizontal axis represents the development potential vb -ver,
The image density is plotted on the vertical axis and the measured data is plotted, and it can be seen that a developing potential of 100 V or more is required to obtain a good image density of 1.0 or more.

On the other hand, the second quadrant shows the developing potential Vb on the horizontal axis and the charging potential Vo on the vertical axis, and each plot point is the memory of the image on the paper P that is generated by one revolution of the photoreceptor 15 due to poor cleaning. It has been found that when the developing potential is higher than 300 V, a memory of a black pattern on a white background is generated due to poor cleaning (hereinafter referred to as "white background memory"). This is considered to be because, although the image density does not increase even when the development potential becomes 300 V or more, the actual amount of toner t attached increases, and the amount of toner t remaining after transfer also increases at the same time.

Next, regarding the third quadrant, here, the horizontal axis is the cleaning potential Vo -Vb, the vertical axis is the charging potential VO, and the paper P
This shows how the above memory image is generated.

Here, if the cleaning potential VCL-Vo-Vb is zero, blank memory will definitely occur due to poor cleaning, and it has been found that at least 50V or more is required.

However, when the cleaning potential increases, positive charges are injected back into the toner t from the developing roller 94, and the toner t, which has changed from negative polarity to positive polarity, is transferred to the unexposed area (uncharged area) of the photoreceptor 15. ), which acts as a filter and reduces the exposure amount of the exposure section 17a, resulting in image defects such as blurring of the exposed image or the appearance of an image from the previous rotation of the photoreceptor 15 as a positive memory in the dot pattern. cause a cause Therefore, it has been found that the maximum cleaning potential is preferably 300 V or less at most, although it depends to some extent on the toner t, the carrier C, and their combination.

Furthermore, the resistance dependence of the memory removing means 20 was investigated. A 30φ OPC photoreceptor 15 rotating at a circumferential speed of 36 mm/sec is first subjected to pre-exposure using a pre-exposure device 21, and charged to -500V using a charging sufrotron charger as a charging means 16. 4 in the forward direction relative to the rotation direction of the photoreceptor 15 at a rotation speed of 140 rpm,
The electrostatic latent image formed by exposure is developed at the same time as cleaning, and is transferred onto paper P by a transfer charger serving as transfer means 19.

After the transfer, the image was passed through a brush 200 fixed to the process cartridge 105, and this cycle constituted one cycle to perform continuous printing and evaluate the transferred image.

In this embodiment, reversal development is used, and during transfer charging as the transfer means 19, the polarity is opposite to that of charging, so the surface potential of the photoreceptor 15 after transfer does not exceed the charging potential, and the charging means 16 Since it is a potential-controlled scorotron, there should basically be no potential fluctuations, but in reality, if the same image is printed for a long time, a difference in residual potential will occur between exposed and unexposed areas due to optical fatigue, as shown in Figure 37. , red L for the purpose of forced fatigue because density unevenness occurs when printing another image.
ED was used.

The resistance dependence of the memory removal means 20 was investigated and the following results were obtained.

The brush used here is a pile weave brush 170 (No. 38 Diagram A.

38B and 38C) was used. In addition, 1 in the figure
71 is a base fabric weft, 172 is a base fabric warp, and 173 is a pile. Here, the specific resistance of the brush 170 is 20°C, 60% RH.
When we tried changing the environment from 10°Ω・cm to 1015Ω・cm, we found that resistivity of 106Ω・cm or less was effective for black negative memory on halftone patterns as shown in Table 1. . However, for practical purposes, a resistance of 10 9 Ω·cm or less was sufficient to remove white positives.

If it is less than 103Ω・Cm, there will be damage to the photoconductor 15 (dielectric breakdown of the photoconductor will occur), and if the hair falls out and comes into contact with the charging means 16, it will leak, and if the charging stops and there is a reversal phenomenon, it will become solid black. Become. Therefore, it is preferably 10 Ω·am to 10 Ω·cm.

Furthermore, it was necessary to apply a positive or negative bias to the black negative memory.

Here, when I tried to transfer the remaining toner t after passing through the brush 170 using a mending tape, as shown in FIG. Although it becomes thinner, there is almost no change and memory still occurs on the image.

However, if the negative bias is of the same polarity as the toner t, the border of the character pattern becomes thinner, but the brush 170 develops the central part of the line of the untransferred pattern where there is no toner tolerance, and the character becomes darker overall. It becomes a pattern.

However, this does not appear as memory on the image. If a positive bias is applied, which is opposite to the polarity of the toner t, the boundaries of the character pattern will become thinner, and no memory will occur on the image. The polarity of the toner t is the polarity obtained by frictional charging with the carrier C. Here, memory removal brush 170 (160
) does not diffuse the toner pattern of the character characteristics remaining after transfer, and the brush 170. (160) is toner t
It has been found that the toner t is once electrostatically attracted and then spontaneously ejected onto the photoreceptor 15, changing the adhesion position of the toner t on the photoreceptor 15. Note that if you only want to change the toner position, it would be possible to provide a means to actively diffuse the toner t instead of using the memory removal brush 170 (160), but in that case, the device itself would have to be large. This is undesirable because it also causes problems such as toner scattering. Further, as a result of a running test with 20,000 images, almost no toner t was accumulated in the brush 170 (160).

On the other hand, for a white positive memory in which untransferred toner is poorly cleaned due to transfer failure due to lifting, wrinkles, or folding of the paper, only Ov, float, or positive voltage was effective.

From these results, it was determined that the bias for brush 170 (160) must be positive. Therefore, the positive bias voltage is set to 1
Examining the pattern of residual toner t after changing the voltage from 00V to 100OV and the memory removal effect on paper P1.
It was found that the effect is almost the same above 00V, and that a positive voltage is sufficient. However, if more than +700V is applied, OPC
(Organic, photoconductor) It has been found that a slight defect (possibly a pinhole) in the photoreceptor 15 causes a voltage leak, which in turn creates a burnt hole in the photoreceptor 15. The appropriate voltage is +100 to +700V. This is the range that can be practically used.

In this embodiment, in order to reduce the size and cost of the apparatus, the photoreceptor 15 is made small with a diameter of 30 mm, and the paper P is made more rigid.
Since only peeling is used, the transfer means (transfer charger) 19 is applied to the part where the paper P does not pass, and as shown in FIG.
That part is positively charged from 00 to 1200V.

Therefore, it has been found that the negatively charged toner t adhering to the brush 170 (160) develops the positively charged portion through which the paper P has not passed.

In particular, the toner t adheres to a large extent near the leading and trailing edges of the paper P, and appears as streaks on the image as white positive and black negative memory (see paper spacing traces in Table 4). To prevent this, apply a positive bias to the brush 170 (160), and as shown in the flowchart of FIG.
The power applied to the corona wire 151 of the transfer means 19 is turned off only when the transfer means (transfer charger) 19 is passing under the transfer means (transfer charger) 19.
NL, the problem could be solved by preventing the exposed parts of the photoreceptor 15 before and after the transfer paper P from being positively charged.

Note that the device of this embodiment can print up to three sheets of paper, but
When printing paper narrower than F3 paper, for example B5 paper, both sides of the paper P on the photoreceptor 15 (because the device always feeds the center of the paper P at the same position regardless of the size of the paper P) is positively charged, but in this case, there is no paper P in this area during printing, so there is no problem at all.

Furthermore, as will be described later, it has also been found that it is preferable for the brush shape to be a satin weave.

Here, the timing of turning on the bias power applied to the brush 170 (160) will be described.

Since a positive voltage (a voltage with a polarity opposite to that of charging) is applied to the brush 170 (160), the photoreceptor 15 is basically charged positively. Therefore, the brush 170 is energized.
If the surface of the photoreceptor 15 that has passed through (160) is not subjected to charging corona by the charging means 16, when that portion passes through the developing means 18, the toner (negative polarity) t of the developer in the developing means 18 will adhere. It ends up turning solid black. Such solid black cannot be cleaned completely and becomes a problem. Therefore, the negative charging by the brush 170 (160) may be changed to a negative charging by the charging means 16. TS-M (third
(see Figure 2), the time from turning on the brush bias power supply to turning on charging must be less than or equal to Ts-λ. In this embodiment, charging and turning on the brush bias were performed simultaneously as shown in FIG. 41.

This problem also occurs when printing is finished.

Therefore, the discharge of the charging means 16 must not be stopped until the surface of the photoreceptor 15 passes through the charging position when it is turned off. That is, the time for turning off the charging must be longer than T5-ia.

Next, change the thickness of the fibers of the brush 170 (160) to examine the effect on the memory of the image and the photoreceptor 15 after passing through the brush.
When we examined the residual toner image above, we found that if it was thicker than 100D, it could not be removed in some areas, especially in the vertical lines. 1
When the thickness was 00D or less, no memory occurred, and the residual toner image after transfer had no dark areas at the boundaries.In conclusion, it is preferable that the fiber thickness be 100D or less.

In addition, the density of the brush 170 (160) is 1000 fibers/1 nch' or more in the case of a pile type, and the thickness is 0.
．． It is not effective unless it is 5mm or more, and for satin weave, 10 bundles/Inc of 10 to 1000 fibers are required.
It has been found that unless the yarn is woven into warp or weft yarns at a ratio of h or more and then made into a brush shape, the memory removal effect will be uneven. The memory removal effect is largely determined by brush resistance, fiber thickness, density, etc., but for practical use of the device, it was found that toner falling (scattering) occurs depending on the shape of the brush and the way it is applied. .

Here, a pile weave brush 170 (see FIG. 38) and 1
100 book fibers with a thickness of 3D are bundled together and a sateen weave brush 16 is used as the warp at a density of 127 bundles per inch.
0 (see Figure 31), length N A % Thickness W
(II child weaving is the number of sheets), angle θ, contact position Ns (32nd
The amount of toner t scattered or falling onto the charging means 16 made of a scorotron was examined by printing at 100 CI (A4 horizontal) by changing the image quality (see figure).

As a result, as shown in FIG. 42A, the pile weave brush 17
There was a lot of toner falling on both the tip end of the brush 0 and the belly end of the pile brush 170 shown in FIG. 32, and the grid of the charging means 16 made of a scorotron was stained black. In addition, the hair sometimes falls out, causing a short circuit with the grid of the charging means 16, resulting in a solid black image.

The brush 160 made of satin weave is not preferably applied in such a way that the tip touches the photoreceptor 15 as shown in FIG. 43, as this causes a lot of toner to fall off and also occasionally leaves gaps between the sheets of paper P.

On the other hand, as shown in FIG. 32, by using the satin brush 160 as a pad instead of a tip, toner dropping was significantly reduced. The optimum application conditions are as shown in FIG. 32, when there is no photoreceptor 15, there is no external force on the brush 160, and the brush 160 is fully extended. Assuming that the point where it intersects with the outer diameter circle is P, and the tangent in the direction of the brush to the photoreceptor 15 at point P is M, the brush length g^ must be 4 mm or more and the installation angle θ must be 45 degrees or less to prevent toner from falling. There were many cases, and the effect was weakened.

Further, as shown in FIGS. 32 and 33, the brush 16
A brush 1 is attached to the surface opposite to the surface that contacts the photoreceptor 15 of 0.
Backing film 16 to prevent the hairs of 60 from spreading
1 was installed, toner drop-off did not occur even after printing 300,000 sheets.

This backing film 161 is insulative and may be made of polyester, urethane, high-density polyethylene, polypropylene, butadiene rubber, butyl rubber, silicone rubber, polyacetal, fluororesin, or any other elastic material with a thickness of 2 mm or less.

However, the tip of the film 161 needs to protrude as much as or more than the tip of the brush 160 (1.5 mm in this example), and if it is recessed, there is no effect.

This is because when the fibers are spread out at the tips, the toner t adheres closely to each fiber with a size of several tens of microns, and falls and scatters due to subtle changes in air flow or vibrations.

Further, the photoreceptor 15, the charging means 16, and the memory removing means 20 are integrated into the developing unit 18 (see FIGS. 1 and 18), and these process cartridges 105 The device body 1 is integrated
It can be taken in and out.

Therefore, even if the photoconductor 15 is removed from the apparatus main body 1, the relative positional relationship between them does not change, thereby making it possible to prevent toner from scattering from the memory removing means 20 and deterioration of the memory removing effect. Become.

Further, since it is a mere fixed type, the cost will not change much even if it is discarded together with the photoreceptor 15.

Note that the electrostatic latent image on the photoreceptor 15 is visualized by the toner t of the developing means 18, and then transferred onto the paper P by the transfer means 19.

Here, the following measures have been taken.

The process speed (photoreceptor circumferential speed) in this example was 36 a.
m/see and a normal copying machine (A4 paper vertical feed 15 sheets/min, process speed 14 Cs+a/seC
It is considerably slower, about 1/4 of the time.

In the case of such a slow process speed, the following problems occur when a corotron charger, which has been conventionally used as a transfer means, is used.

■Since the corona current is small, the voltage applied to the corona wire is low and close to the discharge start point, making it unstable due to dirt and environmental changes.

■The values of the applied voltage or output current of the corona for good transfer of the character part and the solid part (the part where the toner is applied over a wide area) are different, and it is difficult to obtain a high-quality transferred image in both parts.

These causes are attributable to the fact that the transfer time is longer due to the slower process speed.

Basically, toner t can be transferred by applying an electric charge to paper P until the potential of paper P reaches a potential that electrostatically attracts toner t.

Therefore, since the process speed is slow, a suitable transfer current is generated when the voltage applied to the corona wire is about 3.5 to 4 kV, and if it is higher than that, excessive transfer occurs. However, as shown in Figure 44, the voltage of 3.5 to 4 kV is almost the starting voltage for corona discharge, and the stability may vary depending on the temperature, humidity, atmospheric pressure, amount of dirt, etc. I am very unwell.

In addition, in order to investigate the difference in the transfer conditions between the character part and the solid part image of ■, solid characters or a large number of characters were printed within a certain area, a visible image was made with toner t on the photoreceptor 15,
The amount of toner adhering to the photoreceptor 15, both untransferred and after being transferred to the paper P, was collected using a certain area cellophane tape (manufactured by Chiban), and the collected tape was dissolved in a certain amount of toluene to determine the transmittance. By measuring, the transfer efficiency was calculated using the following formula.

Toner adhesion amount after transfer Transfer efficiency - untransferred toner adhesion xt Xl°0 Figure 45 shows the process speed 36 used in this example
The characters (1
j) The transfer efficiency of the image area and the solid area was investigated, and it was found that there is no applied voltage that would result in a transfer efficiency of 80% or more for the character area and the solid area at the same time. In other words, as long as a corotron is used, it is inevitable that the image density of either characters or solids will decrease.

The reason for this is that, as shown in FIG. 46, which shows the potential and charge movement of the paper P, the paper P is separated from the photoreceptor 15 in the solid area due to the presence of toner t between the paper P and the photoreceptor 15, and Since most of the toner t except for the toner t retains the charge received from the transfer corona, the potential of the paper P hardly decreases, and the toner t is transferred to the paper P by electric force.

On the other hand, since the width of the toner image in the text area is narrow, the charge on the paper P above the toner t is absorbed by the opposite charge on the unexposed part of the photoreceptor 15 next to the toner image, and the potential of the paper P does not rise. .

Therefore, if the solid area is transferred properly, the character area of the paper P
The potential of the transfer layer becomes low, and the transfer efficiency deteriorates. Conversely, if you try to raise the potential of the paper P in the text area, the potential in the solid area will rise too much, and the toner t in the solid area will receive leakage current from the paper P, causing the polarity to reverse, changing from negative to positive, making it difficult to transfer. Become. In other words, excessive transfer occurs.

In order to eliminate such problems, a scorotron charger similar to the charging means 16 was used as the transfer means 19. By using a scorotron charger, a voltage of 5 kV or higher can be applied to the corona wire 151, which not only stabilizes the discharge but also prevents charge jams from occurring due to dirt and the like. Further, since the potential of the transfer paper P in the solid area and the character area can be controlled to be the same potential, a transferred image with good quality in both the solid area and the characters can be obtained.

Figure 47 shows the transfer efficiency of text and solid areas when using Scotron, which was investigated in the same way as when using Corotron, and it is well controlled, and both solid and text are transferred well at the same time. (Transfer efficiency of 80% or more) This shows that a wide area can be obtained. The shape of a scorotron is almost the same as a charged one.

Here, the transfer scorotron opens downward with respect to the photoreceptor 15, but since it is a positive corona, almost no ozone is generated and there is no problem at all, unlike negative charging. Here, we investigated the appropriate value of the scorotron grid voltage by measuring the transfer efficiency.

Table 2 shows how good or bad the transfer efficiency was for various transfer papers Pl:J by changing the grid voltage.

According to this, good transfer (efficiency 8.
It was found that the regions of grid voltage are different (more than 0%).

Therefore, in order to achieve good transfer on all types of paper, the voltage of the grid should be at least 2Fl depending on the paper.
It is necessary to switch to a voltage of class I or higher.

In this example, it is 1200 V when using envelopes, and + when using other paper.
The 700-inch two-stage design has a knee that switches the output of the grid transformer depending on the signal. It goes without saying that the grid voltage may be switched in multiple stages depending on the type of paper.

Here, when using a scorotron as the transfer means 19, one of the things to consider is countermeasures against dirt on the grid of the scorotron. Usually, the transfer means 19 is attached below the photoreceptor 15. Therefore, the opening faces upward, and the paper P passes above it. At this time, toner particles on the photoreceptor 15 and paper dust from the paper P inevitably fall onto the transfer means 19. Transfer means 19
If you turn it into a scorotron, you will definitely need a grid of 150J.
Toner t or paper powder may fall and adhere to the grid 150a, and during printing tens to tens of thousands of sheets, the grid 150a may become extremely dirty, or the mesh may become clogged, resulting in poor transfer. turn into.

Therefore, in this embodiment, the transfer position is set above the photoreceptor 15,
By providing the Scorotron transfer means 19 above it, the opening on the grid 150a side faces downward, thereby preventing the grid 150a from becoming dirty as described above (see FIG. 3).

The transferability was examined by changing the voltage of the Zener diode, varistor, resistor, power source, etc. on the guide plate 180 and the conductive guide roller 25 shown in FIG. 4. As a result, it was found that even in the scorotron, the transferability changes depending on the potential of the guide plate 181 and roller 25.

Table 3 is an evaluation table of the results.

When a scorotron is used, it has been found that when a voltage is applied to the guide members 181 and 180, transfer defects due to excessive transfer tend to occur.

For this reason, the guide member 1 for the paper path of the paper P as in the past.
Applying a voltage, resistance, or self-bias to 81, 180 with a constant voltage element causes excessive transfer in the case of scorotron transfer, resulting in bad results.

Rather, it is most preferable that the ground (earth) be a float (electrically insulated). Therefore, in this embodiment, the guide plate 1
81 and roller 25 were connected to ground, and other contact parts were made of insulating material (for example, ABS resin).

Here, we will discuss N types of memories in which a pattern developed one cycle before the photoreceptor 15 appears on the next image area, which is peculiar to simultaneous cleaning and development (CDP'), and the causes of occurrence.

There are three types of memory: ■Positive black pattern on a white background (white positive); ■Negative pattern on a halftone (black negative) made from a collection of dots or lines; ■Network made from a collection of dot patterns or lines. This is a positive pattern (black positive) on a dotted halftone (see Fig. 48).

The cause of the white positive in (①) is poor cleaning, and the cleaning potential VC is the difference between the charging potential and the developing bias Va.
This occurs when L is too small.

The cause of the occurrence of black negative memory (2) is due to poor exposure due to the transferred residual toner image.

The black positive memory (3) is caused by the low resistance of the toner when the cleaning potential is too high.

FIG. 49 shows the principle of generation of black negative memory that tends to appear on the halftone halftone pattern of dots or line aggregates, with the vertical axis representing the surface potential and the horizontal axis representing the distance.

(a) shows the surface potential of the photoreceptor 150 where there is a little amount of toner remaining after transfer during the charging process (section a), a large amount (section b), and no toner at all (sections c and d).

(b) shows the surface potential when laser spots are irradiated onto the photoreceptor 15 at intervals of every other dot; (c,
Since part d) is a normal exposure, the potential is attenuated approximately equal to the laser exposure width. In part (8), since the amount of toner remaining after transfer is small, the potential under the toner is considerably attenuated by transmitted light, diffracted light, etc., and is close to the potential of the exposed area where no toner exists. On the other hand, in the part (b) where there is a large amount of untransferred toner, the toner does not hit the photoreceptor part under the toner and the potential does not attenuate, so the part where the potential attenuates becomes narrow or disappears altogether.

(c) and (d) show the potential diagram when the exposure state in (b) is reversely developed and the pattern on paper P after heat fixing.
When there is no residual toner at all (part 06), a toner image is formed in a pattern with approximately the same diameter (width) as the exposure spot diameter (width), but when there is a lot of residual toner (part b), the potential is attenuated. Since the pattern is narrower than the exposure spot diameter (width), the developed pattern is also small or disappears altogether. The remaining toner after transfer is then cleaned (recovered in the developing device). Therefore, if a portion with a large amount of untransferred toner forms a pattern of letters or numbers, a blank negative memory will result (the portion marked ■ in FIG. 48).

On the other hand, in areas (area a) where residual toner remains after transfer, the potential under the toner is also attenuated or attenuated to some extent, so the toner remains attached without being cleaned, so the pattern after development is not much different from (areas e, d). , a pattern image with approximately the same diameter (width) as the exposure spot is obtained. In addition, even if the potential under the toner is not sufficiently attenuated, if the size of the toner particle is about 1.2, the exposure spot diameter should be the diameter of the toner particle (usually 8 to 1
0 um (400 dots/In)
ch) and the thickness of the developed toner layer is thick, so it gets buried during development or fixing, causing virtually no problem.

By the way, as mentioned above, the cause of black negative memory is the filter effect caused by the residual toner after transfer.
For solid solid images, halftone images, and lines of 5 dots (400 dots/inch) or more, black negative memory does not occur by adjusting the amount of laser light, the structure of the photoreceptor, the transmittance of toner, etc.

However, 4-dot lines or less are more likely to occur.

This is particularly noticeable at the edges of lines, and when characters are composed of four dot lines or less, they look like characters with whitish edges.

Here, when the remaining transfer pattern of the character image on the photoreceptor 15 is adhesively transferred using a mending tape (3M company), as shown in Fig. Too much toner.

FIG. 51 is a cross section of the portion X to X of the residual transfer pattern in FIG. 50, and it can be seen that a large amount of the residual transfer toner remains in the boundary area in a layered manner. Note that 190 shown in FIG. 51 is a tape. Therefore, almost no light passes through this boundary, which causes black negative memory.

This layered remaining transfer toner at the boundaries of characters and line patterns is broken down to create a single layer that does not cause memory. Alternatively, the black negative memory is prevented by removing the laminated portion by electrostatic attraction.

Therefore, the memory removing member 20 which performs the above action is used as a transfer means]
9 and upstream of the charging means 16.

FIG. 53 shows that the memory removing means 20 is attached to the photoreceptor 15.
It is arranged in a non-contact manner.

The brush member 160 constituting the memory removing means 20 and the photoreceptor 15 do not need to be in contact with each other, and as long as they have a gap of a predetermined distance, the above-mentioned effects can be sufficiently obtained. In this case, the voltage is applied to the memory removing means 20 as described above, and the toner remaining on the photoreceptor 20 is electrostatically attracted by the memory removing means 20.

FIG. 56 shows how the memory removing means 20a and 20b are removed from the photoreceptor 1.
A plurality of (two in this embodiment) are provided along the rotational direction of 5. These memory removal means 20a, 20
The configuration of b is the same as described above. The brush members of the upstream memory removing means 20a and the downstream memory removing means 20b may have the same thickness, but
The thicker the thickness of the brush member, the more desirable results can be obtained.

However, the thickness is limited to the range mentioned above.

Further, it is desirable that the upstream memory removal brush 20a has a brush member with a higher electrical resistance than the downstream memory removal brush 20b. However, in this case as well, the resistance is limited to the electrical resistance of the brush member described above. Note that the brush members of the memory removal brushes 20a and 20b may be made of different materials.

FIG. 54 shows an example of how the control panel 11 described above is attached to the main body of the apparatus. The control panel 11 comes from the unit lla and is rotatably attached to the frame portion 1a of the main body of the apparatus via a support shaft 11b. The support shaft 11b also serves as a wire passageway to enable electrical connection between the unit lla and the main body of the apparatus. With this configuration, the control panel can be placed in an upright position with respect to the main body of the apparatus, so that operability and visibility can be significantly improved. Note that the method of attaching the control panel is not limited to the above-mentioned method.
A similar effect can be obtained by being rotatably supported with respect to the main body of the device.

Next, the control panel 1'1 includes a fluorescent display tube 11C and a key switch lid for turning on and off the fluorescent display tube display. This fluorescent display tube 11c and key switch ll
The operation of d will be explained with reference to FIG. When the power is turned on, the fluorescent display tube 11C is in an on state and performs display. When an image forming start key (not shown) is turned on in this state, the image forming operation is started. On the other hand, if the start key is not turned on, the fluorescent display tube is turned off and the display is turned off by turning off the key switch lid. In this case, the operation of the cooling fan unit 29 is stopped or decelerated. The image forming operation described above is started only when the fluorescent display tube 11C is displaying the image. Furthermore, by turning on the key switch 11d, the display on the fluorescent display tube 11 is turned off.
When c is turned on, the display control returns to the state at power-on.

With such a configuration, the power consumption of the entire device can be reduced.

FIG. 57 shows a cleaning blade 300 and the above-mentioned memory removing brush 20 arranged in combination as memory removing means. The cleaning blade 300 is
It is made of an elastic member (for example, a urethane sheet material) with a thickness of about 0°1 to 3 cm, and is
It is provided upstream of the arrangement position of the memory removal brush 20.

The cleaning blade 300 peels and removes residual toner from the photoreceptor 15. A hole 300a is formed in the cleaning blade 300, and residual toner peeled off and removed by the cleaning blade falls downward in the figure through the hole 300a. This falling residual toner is once sucked by the memory removal brush 20 and returned to the photoreceptor, thereby producing the same effect as described above.

Next, a configuration for peeling and transporting the paper P after transfer from the photoreceptor 15 will be described.

As shown in FIG. 3, the photoreceptor 15 and the fixing unit 27
A memory removal brush 20 is provided between the two.

In this embodiment, the polarity of the toner is negative. The transfer charger 19 performs positive discharge, and the paper P that has passed through the transfer charger 19 has a positive polarity charge. On the other hand, in the lower part of the drawing of the paper P passing through, there is a memory removal brush 2.
A holding metal fitting 162 forming a holding member of 0 is located. A positive potential (for example, a bias voltage of about 500 V) is applied to this holding fitting. Therefore, the electric field generated from the holding fitting 162 and the positive charge of the paper repel each other, and the paper P is lifted upward in the figure. Therefore, the paper P after transfer is peeled off from the photoreceptor 15 and smoothly conveyed to the fixing unit 27. Note that a sheet metal member is independently provided in place of the holding fitting 162, and a bias is applied to this sheet metal member. Also good.

FIG. 58 shows the shape of the surface 7b of the paper feed cover 7a, which is detachably provided on the paper feed cassette 7, and which rubs against the paper P. The surface 7b has an uneven shape and has a surface roughness of 10
It is more than μm. With this configuration, the paper P comes into contact with only the convex portion of the surface 7b, a so-called point contact state, and the contact area between the paper P and the paper feed cover 7a is significantly reduced. Therefore, the generation of frictional electricity between the paper P and the paper feed cover 7a is reduced, and the paper feed cover 78 and the paper P
Since the paper is not attracted by static electricity, the paper can come out smoothly from the paper feed cassette 7.

Figure 58 (°a) is an example in which the surface 7 is formed into a matte finish, Figure 58 (b) is an example in which the surface 7b is formed in a hairline (unidirectional) shape, and Figure 58 (C) is an example in which the surface 7b is formed into a hairline (unidirectional) shape. FIG. 58(d) is an example in which the surface 7b is formed in a hairline shape, and FIG. 58(e) is an example in which the surface 7b is formed in a hairline shape. FIG. 58(f) shows an example in which the surface 7b is formed into a tile shape, and the surface 7b may have any shape.

Next, details of the developing means 18 will be explained with reference to FIG.

A cleaning member 18c is provided in the casing portion 91 of the developing means 18, which is close to the optical system unit 34, and has a double structure by pasting an elastic member 18b such as felt to a member 18a such as a press-contact member 18a such as a malt brain. ing. This cleaning member 18C is the optical system unit 3
4, and when the developing means 18 is taken out of the apparatus main body and when the developing means 18 is inserted into the apparatus main body, the light emitting surface of the optical system unit 34 is slid along the elongated direction. come into contact with Therefore, the optical system unit 34
8, dirt such as scattered toner will be periodically cleaned.

C. Effects of the Invention As described above, according to the present invention, in an image forming apparatus including an image bearing member and a memory removal brush, a cleaning process is performed simultaneously with development, and waste toner caused by untransferred toner from the previous image forming cycle is removed. It is possible to provide an image forming apparatus that can prevent image formation and obtain good images, and that can further reduce the size and cost of the entire apparatus and improve maintainability.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a perspective view of the process and unit that is the main part of the invention, FIG. 2 is a perspective view of the overall appearance of the image forming apparatus, and FIG. 3 is a schematic longitudinal section. A front view, FIG. 4 is a schematic longitudinal sectional front view showing the configuration of the main parts,
FIG. 5 is an explanatory diagram showing changes in the back surface potential of the recording device of the present invention and the state of toner on the photoreceptor according to the process, FIG. 6 is a cross-sectional view of the photoreceptor, and No. An explanatory diagram showing the irradiation state when the light is on, Figure 8 is C.
A diagram showing the relationship between environmental conditions and residual potential when changing the TL film thickness, FIG. Figure 11A is an explanatory diagram for explaining the effect of insufficient exposure when the exposure pattern is a single pine pattern, and Figure 11B is an explanatory diagram for explaining the influence of insufficient exposure when the exposure pattern is one line. Figure 12 is a plan view of the charging means as seen from the grid side, Figure 13 is a front view, and Figure 14 is the 12th factor A.
15 is a side view in the direction of arrow B in FIG. 13, FIG. 16 is an explanatory diagram showing the state in which the electrostatic latent image forming means is removed, and FIG. 17 is a schematic diagram of the process unit. 18 is a plan view, FIG. 19 is a side view of one end, FIG. 20 is a side view of the other end showing only the developing means, and FIG. 21 shows the driving force of the photoreceptor. 22 is a diagram schematically showing the power supply state to the auto-toner ring, FIG. 23 is a partially cutaway plan view of the transfer means as seen from the grid side, and FIG. 24 is a sectional view of the vicinity of the transmission side. arrow view A
FIG. 25 is a sectional view taken along the line C-C in FIG. 23, FIG. 26 is a sectional view taken along the line C-C in FIG. 23, and FIG. 27 is a plan view of the memory removing means. Figure 28 is a front view, Figure 29 is a bottom view, Figure 30 is Figure 23C.
31 is a perspective view of the satin weave brush constituting the memory removal member, 32 is a view showing the mounting state, and 33 is the state of the backing film of the brush. FIG. 34 is a diagram schematically showing changes in surface potential and the state of toner on the photoreceptor according to the process when cleaning is performed simultaneously with regular development, and FIG.
The figure is an explanatory diagram of the surface potential. The 36th factor is an explanatory diagram showing the relationship between the development potential and image density, the development potential and charging potential, and the cleaning potential and charging potential. Figure 37 is the state of the potential after exposure. FIG. 38A is a perspective view of the pile weave brush constituting the memory removal member, FIG. 38B is a partially enlarged view of the pile weave brush, and FIG. 38C is a partial sectional view of the pile weave brush. Fig. 39 is an explanatory diagram showing the remaining transfer pattern after passing through the brush placement section, Fig. 40 is a diagram showing the surface potential on the photoreceptor after transfer when the transfer corona is continuous, and Fig. 41 is during printing. Figure 42A is an explanatory diagram when the tips of the pile weave brushes are used in contact with each other, Figure 42B is an explanatory diagram when the tips of the pile weave brushes are used in contact with each other, Figure 43 is an explanatory diagram when the tips of the satin weave brushes are used in contact with each other.
Figure 44 is a diagram showing the relationship between applied voltage and discharge current during transfer, Figure 45 is a diagram showing the relationship between applied voltage and transfer efficiency for text and solid images by a corotron charger, and Figure 46 is a diagram showing the relationship between transfer efficiency and transfer paper. Explanatory diagram showing the potential and charge leak state, 4th
Figure 7 is a diagram showing the relationship between the voltage applied by the scorotron charger and transfer efficiency, Figure 48 is an explanatory diagram showing examples of memory patterns that tend to appear on transfer paper, and Figure 49 is a diagram showing the potential of the photoconductor when black negative memory occurs. 50 is a diagram showing an example of a residual transfer pattern, FIG. 51 is an explanatory diagram showing the state of toner in the section XX in FIG. 50, and FIG. 52 is a cross-section of the brush. 53 is an explanatory diagram when the tip of the brush is used in a non-contact state with the photoreceptor, FIG. 54 is a partially cutaway diagram showing the operating section, and FIG. 55 is a flowchart showing operation control of the display means. , FIG. 56 is a sectional view when a plurality of brushes are used, FIG. 57 is a sectional view when a blade and a brush are used, and FIG. 58 is a diagram showing the shape of the paper feed cover surface. 15... Image carrier (photoreceptor), 16... Charging means,
17... Exposure means, 18... Developing means, 19...
Transfer means, 20...Memory removal means, 160.170
...brush, t...toner Figure 2

Claims (1)

[Claims] An image forming apparatus that performs an electrophotographic process on a rotating photoreceptor that can be used repeatedly to form a surface image includes a charging means for charging the photoreceptor, and a method for exposing the photoreceptor charged by the charging means to light. An exposure means for forming a charge pattern, and simultaneous development for attaching a developer to the charge pattern on the photoreceptor formed by the exposure means to form a visible image and removing excess developer remaining on the photoreceptor in advance. A cleaning means, a transfer means for transferring the visible image formed by the developing and simultaneous cleaning means from the photoreceptor to the transfer material, and a plurality of electrification means along the rotational direction of the photoreceptor between the transfer means and the charging means. 1. An image forming apparatus comprising: a memory removing means formed by bundling a large number of conductive artificial fibers arranged in parallel and having an uneven shape around the periphery and having a volume resistivity of 10_2 to 10_7 Ω·cm.