JPS62226173A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent all of ground fogging, ground staining, and ghost image formation from being caused by performing magnetic brush development by using a developer formed by mixing powder for development with powder for cleaning as powder other than toner. CONSTITUTION:A developing device uses a developer obtained by mixing the powder for development with the powder for cleaning as powder other than toner. The powder for development is low-resistance magnetic carriers and charges having polarity reverse to that of an electromagnetic latent image are implanted to the surface; and an electrode is formed nearby a photosensitive body to generate an intense electric field between the electrode and latent image, and then the latent image on a photosensitive body is visualized with sufficient image density. The powder for cleaning are high- resistance carriers, so part of toner sticking on the surface of the photosensitive body is attracted to a latent image boundary part and other toner is attracted onto a developing sleeve. Those toner particles leave the surface of the photosensitive body and charges having polarity reverse to that of the toner are left on the surfaces of the high-resistance carriers locally and never discharged unless leaking to the developing sleeve surface. Therefore, the transfer remaining toner at the time of repetitive use is guided by the opposite-polarity charges on the high-resistance carrier surfaces and attracted and recovered efficiently and securely.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention is directed to forming an electrostatic latent image by irradiating a charged image carrier with light such as a laser beam. The present invention relates to an image forming apparatus that includes a step of developing and making an image visible, and particularly relates to an improvement of an image forming apparatus that simultaneously performs a developing step and a clearing step using the same developing device.

(Prior art) In general, in copiers, laser printers, etc. that use an electrophotographic recording process, photoconductors are used repeatedly. a transfer step in which is transferred to a transfer member;
During an electrostatic latent image forming step in which an electrostatic latent image is formed by charging and exposing the photoreceptor, a photoreceptor clearing step is provided to remove powder remaining after transfer on the photoreceptor.

For example, FIG. 10 is a cross-sectional view of a conventional laser printer. In this laser printer, the photoreceptor 2 is uniformly positively charged by the charging charger 6, while the laser beams 1 and 8 scanned by the polygon mirror are The lens 3 condenses and exposes the photoreceptor 2, and as in the case of semiconductor laser light, the charge on the photoreceptor 2 is attenuated by exposure by turning the power ON/OFF to form an electrostatic latent image.

This electrostatic latent image on the photoreceptor 2 can be formed by applying a predetermined developing bias to the developing sleeve 19 of the developing device 5.
The image is developed by this developing device 5.

This developed powder image is transferred to the transfer member p by the transfer charge +711, and fixed to the transfer member P by the fixing device 13.

On the other hand, the transfer residual powder remaining on the photoreceptor 2 without being transferred to the transfer member P by the transfer charger 11 is removed by the cleaning device 16.
is removed from the photoreceptor 2 by a cleaning blade 17 .

The thus cleaned photoreceptor 2 is decharged by the static eliminating lamp 7 and charged again by the charging charge t6, so that the above-described image forming process can be continued.

FIG. 11, FIG. 12, and FIG. 13 show each process of a conventional example when viewed from the top of the process of repeatedly using a photoreceptor.

In Figure 11, (1) → (2) → (3) → (4) →
The flow of <5) → (6) → (1) is a type in which powder of opposite polarity to the electrostatic latent image on the photoreceptor is adsorbed to the charged part of the photoreceptor for development, that is, the photoreceptor is repeatedly used in the regular development process. It shows the process of

In Figure 12, (1) → (2) → (3) → (4) →
The flow of (5) → (6) → (1) is a type in which powder of the same polarity as the high potential area is adsorbed to the exposed area of the electrostatic wI image on the photoreceptor for development, in other words, the photoreceptor repeats the two-component reversal process. Showing the process of use.

In Figure 13, (b)→(2)→(3)→(4)→
The flow of (5) → (6) → (1) is to induce or inject charges into the one-component powder from the developing roller into the electrostatic latent image discharge area of the photoconductor, and thereby cause the charged one-component powder to be adsorbed. It shows a developing type, that is, a one-component reversal development process using a photoreceptor.

As is clear from these three examples, in order to use the photoreceptor repeatedly, it has become necessary and essential to remove the powder remaining after transfer from the photoreceptor during the transfer process.

In fact, in the regular developing broth shown in Figure 11, the cleaning process (5
) is omitted and the static electricity removal process is performed directly, that is, (1)
-→(2)′→(3)→(4)→(6)′→0)′→ In professional wrestling, the photoreceptor is repeatedly used, and the powder remaining after transfer is charged in the charging step (1)′ and then exposed to light. Even if the charged powder remaining in the exposed area goes to the development step (3), the residual potential of the photoreceptor after exposure and the development bias are almost the same, so it is not cleaned during development and remains as it is. In the next transfer step (4), the toner is transferred to the transfer member, causing deterioration in development such as ghost images, background blurring, and scumming.

Furthermore, even in the reversal development process using two-component and one-component developers shown in FIGS.
)′→(2)′→(3)→(4)→(6)′→(1)′
→ In the process of repeatedly using the photoconductor, after passing through exposure (2) -, the untransferred charged powder remaining on the charged part of the electrostatic latent image is removed by the development bias V6 applied to the surface of the charged part of the photoconductor in the developing step (3). Since the potential is set almost equal to the potential (6), it remains without being cleaned and is transferred to the transfer member in the transfer step (4) of the same method as in the case of FIG. It is clear that this is also a factor in deteriorating image II.

Therefore, in the process of repeatedly using the photoreceptor as shown in FIGS. 11, 12, and 3, the transfer step (4) and the charging step (
It is essential to provide a cleaning process for the photoreceptor during step 1).

However, to provide such a cleaning device, the cleaning device must be installed first, which requires a larger space, which creates the problem of making the recording device larger. .

Second, press a cleaning member such as a cleaning blade against the photoconductor and press W! Applying mechanical stress such as Im to the photoreceptor,
If a distance of 11 m is applied to the photoreceptor, powder or the like may be closely adsorbed onto the photoreceptor, causing film forming and deterioration of the image.

In order to overcome these drawbacks, the cleaning device was omitted; - During the image forming process, the photoreceptor was rotated twice, the developing bias was changed every two revolutions, and the developing device, which was responsible for the developing process every revolution, was replaced. are made to act as cleaning means. FIG. 14 shows the process of repeatedly using this photoreceptor.

In Fig. 14, the photoreceptor rotates approximately - at the steps (1) → (2) → (3) → (4) → (5), and in the next approximately one rotation (5) → (
6)→(1) cleaning process is performed.

In FIG. 14, the photoreceptor is uniformly charged with Φ in the charging step (1), and the surface potential becomes Vo. exposed in the exposure step (2),
Quiet? The llR latent image is formed. In the developing step (3), a powder of opposite polarity to the charged charge is adsorbed to the charged part of the electrostatic latent image by a developing row biased to a potential that is approximately the same as or slightly larger than the remaining 5 J voltage of the exposed discharge part of the photoreceptor. and develop it. In the transfer step (4), the developed powder image is transferred to a transfer member by a transfer charger. Thereafter, in a static elimination step (5), the photoreceptor is electrically neutralized using a static elimination light and a static elimination charger.

Here, the photoreceptor rotates approximately once. Thereafter, the bias VB of the developing roller is set between O<Va<Vo. Here, the developing roller transforms into a cleaning means and removes the powder remaining after transfer on the photoreceptor from the photoreceptor.

In this way, two rotations and one recorded image are formed. However, in this process of repeatedly using the photoreceptor, the circumference of the photoreceptor must be recorded at least once! It must be longer than the length of the J image.

In other words, if the circumference of the photoconductor is shorter than the length of one recorded image, - when the leading edge of the second recorded image on the photoconductor reaches the developing roller position, the trailing edge of the first recorded image on the photoconductor is not yet developed. Since the developing roller cannot move as a cleaning means during the process, the powder remaining after transfer at the leading end of the photoreceptor of one recorded image is cleaned from the photoreceptor (it is not suspended).

Therefore, it has the disadvantage that the circumference of the photoreceptor, that is, the outer diameter, has to be increased, and the second rotation
Rotation must not be used as a cleaning process; therefore, the usage efficiency of the photoreceptor is only 50%, which is extremely poor. For this reason, there are problems such as the need to slow down the speed, and also problems such as the need to prepare two bias power supplies in order to change the bias of the developing roller. Further, in an electrophotographic apparatus using a reversal development process using a two-component developer, a cleaning process is provided between the transfer process and the charging process, as shown in FIG. I have been doing photoconductor cleaning II.

By the way, the structure of the conventional electrophotographic recording apparatus has the following problems in addition to the above-mentioned drawbacks.

First, since the cleaning device occupies a certain volume, there is a restriction on the conveyance path of the transfer member. For example, as shown in FIG. 8, the conveyance path of the transfer member is a straight path for the reasons mentioned above.

Therefore, when a transfer member is jammed in the apparatus, there is a problem in that in order to remove the jammed transfer member, the transfer member must be separated vertically with the conveyance path as a boundary.

The position of the cleaning means shown in FIG. 11, which will be described later, is an ideal position for the cleaning means, and for this reason, the conveyance path of the transfer member must also be a straight path. In addition, since the insertion direction of the transfer member and the direction of ejection of the transfer member are below the machine body and in completely opposite directions, one combo of system equipment such as a laser printer, for example.
This is extremely inconvenient for a neto device. It is a CRT
It is natural for a worker sitting facing a display to be able to discern the printed content based on his or her sitting position, and all devices are placed with their backs to the wall. This is because it is one of the particularly required characteristics.

(Problems to be Solved by the Invention) Conventionally, in an electrophotographic apparatus that uses a reversal development method, the developing process and cleaning process are performed in the same developing device, and in an image recording method in which the developing process and cleaning process work simultaneously, transfer It was impossible to completely remove the remaining powder without any problems. Therefore, special cleaning means must be provided, which is an obstacle to the goal of miniaturization of the device or ease of handling of system equipment such as the Wardbrossenna.

The present invention has been made in view of the above, and an object thereof is to significantly improve the efficiency of the cleaning process when the same developing device performs the developing process and the cleaning process at the same time.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, in the image forming apparatus of the present invention, the developing device uses a developing powder and a cleaning powder as powders other than toner. It is characterized in that it uses a mixed developer to perform magnetic brush development.

(Function) The powder for development is a low-resistance magnetic carrier, and the powder for Sei 1 and i is a high-resistance magnetic carrier.

Among these, the developing powder has low electrical resistance, so charges of opposite polarity to the electrostatic latent image are injected onto the surface of the low-resistance carrier, and electrodes are formed close to the photoreceptor to form the latent image. A strong electric field is generated between the Therefore, the latent image on the photoreceptor can be visualized with sufficient image density.

Since the cleaning powder is a high-resistance gear, some of the toner adhering to the surface of the photoreceptor is adsorbed to the latent image boundary (edge), and the toner in the pond is adsorbed onto the developing sleeve. Due to the 1!1111i of these toners, a charge having a polarity opposite to that of the toner remains locally on the surface of the high-resistance carrier.

Moreover, since the cleaning powder is a high-resistance carrier, no charge is discharged unless it leaks onto the surface of the developing sleeve.

Therefore, the toner remaining after the transfer after repeated use is guided by the opposite polarity charge on the surface of the high-resistance glass V and is efficiently and reliably adsorbed and collected.

Furthermore, the toner that is detached from the high-resistance carrier V and adheres to the image boundary (edge portion) is effective in ensuring an appropriately selected resolution, and can provide excellent image quality.

For this reason, it is extremely useful for downsizing this type of image forming apparatus, since no trouble occurs even if no separate hanging means is installed.

(Embodiment) FIG. 1 is a sectional view of an electrophotographic recording apparatus according to an embodiment to which the image forming apparatus of the present invention is applied.

In the figure, 1 is a housing, 2 is a photoreceptor, and around this photoreceptor 2, a charging charge V6, a developing device 5, a transfer charger 11, a paper static eliminator charger 12, and a static eliminator 7 are arranged in order. ing.

Further, 3 is an Fθ lens, 4 is a polygon mirror, 8 is a storage container for a transfer member, 9 is a paper feed roller, 10 is an aligning roller, 13 is a fixing device, 14 is a paper ejection roller, 15 is a recording paper storage tray, 18 is a laser beam, 1 is a developing sleeve, 20 is a magnet, and 22 is a developer.

In addition, in this recording device, the circumferential speed of the photoreceptor is 266°0 mm/
sec, photoconductor diameter: 600mm, radar on photoconductor
Power: 3.5mV.

Next, the operation of this device will be described.

When a printing command is transmitted to this device, the drive motor first rotates and each part of the device operates. Charge one unit at the same time -
6 and the static elimination lamp 7 are turned on for 5W.

Now, the photoconductor 2 is rotated at a rotation speed of W radian/sec, and at this time, the laser beam 18 is emitted onto the photoconductor 2, which is uniformly positively charged by the charging charger 6.
, and an N Hative electrostatic latent image is formed on the photoreceptor.

Assuming that the phase difference between the charging charger 6 and one developing sleeve is θ1 radian, the leading end of the electrostatic latent image reaches the developing sleeve 19 after θ+/W seconds. At this time, a developing bias (6) is applied to the developing sleeve 19. The developing bias V1 is set to approximately half the surface potential Vo of the unexposed portion of the photoreceptor 2, VO/2 (0<Ve<Vo).

Therefore, the colored powder, which is positively charged with the same charging polarity, that is, O, is adsorbed to the exposed portion of the electrostatic latent image formed by exposure to the Rade light, and the unexposed portion of the electrostatic latent image is The powder is not adsorbed by Ner)atiVe.
The electrostatic latent image is developed by the developing sleeve 19.

On the other hand, in synchronization with the movement of the electrostatic latent image on the photoreceptor, the transfer member P is sent out from the transfer member storage container 8 toward the aligning roller 10 by the paper feed roller 9 . Furthermore,
The transfer member P and the electrostatic latent image are registered and moved to a transfer position by rotating the aligning roller 10 at a preset timing. When the transfer member P reaches the image transfer position, that is, after θ3/W seconds (here, θ3 is the phase difference between the developing roller 19 and the transfer charger 23) after the development bias V6 is applied, the transfer charger 11 and the paper Static elimination 1! - The jar 12 is turned on 5W at the same time.

In this way, a θ charge is applied from the back surface of the transfer member P, and the potential of the transfer member P decreases, whereby the developed powder layer on the photoreceptor moves onto the transfer member P. Thereafter, the transfer member P is neutralized by the paper neutralization charger of the AC charger biased to IKV, peeled off from the photoreceptor 2, folded along the paper guide 24, and held between the heating rollers of the fixing device 13. Here, the powder image on the transfer member is melted and transferred to the transfer member P.
will be established. After this, the transfer member P is further transferred to the discharge roller 14.
The paper is rotated and held, ejected from the device, and stacked on a paper ejection tray.

On the other hand, a part of the powder layer transferred to the transfer member P is removed from the photoreceptor 2.
remain on top. The behavior of the transfer residual powder on the photoreceptor 2 will be explained along the process of repeated use of the photoreceptor shown in FIG. According to the above explanation, each process is (1) → (2) →
(3)→(4) and the transfer step (4) has proceeded.

Here, a method for repeatedly using the photoreceptor of the electrophotographic recording apparatus of this embodiment in the case where one more sheet of printing is performed after the transfer step (4) will be described.

Most of the powder image reversely developed on the photoreceptor in the transfer step (4) (transfer efficiency: 80%) is transferred to the transfer member. However, as shown in the figure, some of the powder remains on the photoreceptor,
This leads to the static elimination step (5). At this point, almost all of the adsorbed charges on the photoreceptor are attenuated. In this manner, the photoreceptor and the powder remaining on the photoreceptor are uniformly charged in the charging step (1>).

However, the experimental results shown in Figure 2 revealed the following. In other words, when a photoreceptor is charged from above a powder layer developed with a reflection density of about D=1.3, most of the charge passes through the powder layer and the surface of the photoreceptor is uniformly charged. The fact is that it happens.

FIG. 2(a) is a schematic diagram of the experimental apparatus, showing a state in which black toner is uniformly adhered to the photoreceptor 2 up to D=1.3 using a two-component developing roller 31 with a bias of +400V applied. . Thereafter, the powder layer on the photoreceptor is uniformly charged by a charging chamber 6.

Next, the surface potential of the photoreceptor is measured from above the powder 1 using a surface electrometer A. This is the 1st shift shown by the horizontal axis in figure (b).

Furthermore, after that, the powder & on the photoreceptor is completely removed using the cleaning blade 17, and the surface potential of the photoreceptor without the powder layer is measured using a surface potential meter B. This is 11 on the horizontal axis in figure (b)! It is I. When the potential at surface electrometer A is +700V, the voltage 1V falling at surface electrometer B is about +500V.

Therefore, in this state, the surface potential carried by the powder layer is approximately +2
It becomes 00V. However, in reality, photoconductor 2 (a - 3e
) and the cleaning blade 17 (urethane foam), it is known that the photoreceptor is charged to about -100 (V) by friction, so the actual surface potential carried by the powder layer is about 100V.

In other words, it can be seen that even if a powder layer with a concentration of D-1, 3 is charged on the photoreceptor without adhering to it, most of the charged charge goes to the surface of the photoreceptor. Let alone 1
Real/i! ! As in the example, since the transfer efficiency of the transfer residual powder is about 80%, it is as thin as about 20%.

Therefore, even if the remaining powder layer on the photoreceptor is charged as in this embodiment, the photoreceptor can be charged uniformly with the bandffl? Most of the If load wraps around the underside of the residual powder layer.

Next, when we return to the process of repeatedly using the photoreceptor using the reversal development method in Figure 12, the next exposure process fS! In (2), the charged photoreceptor described above is exposed.

In this case, it is possible that the aforementioned transfer residual powder may exist in the exposed area.

Therefore, uniform solid development (photoreceptor density D = 1.3) I is applied to a uniformly charged photoreceptor, and the transfer efficiency is changed by changing the strength of the transfer charger, and the remaining powder layer is removed. The ring was recharged to +750V from above, and the surface voltage of the photoreceptor when exposed to laser light was examined.

The results of this experiment are shown in FIG. As can be seen from FIG. 3, when the transfer efficiency exceeds about 70%, the surface potential of the photoreceptor drops to about 80V. This is exactly the same as the residual potential of the photoreceptor during normal exposure. In other words, it can be seen that when the transfer efficiency is 70% or more, the powder layer remaining after transfer on the photoreceptor does not adversely affect exposure. Therefore, the exposure process (
In 2), it can be seen that even if there is powder remaining after transfer in the exposed area, it does not significantly affect the formation of an electrostatic latent image.

In this way, the next developing step (3) is reached. Based on the experiments shown in FIGS. 2 and 3 described above, the following was also confirmed in actual print recording experiments.

In a two-component reversal development process like this example,
The transfer residual powder present in the charged part of the electrostatic latent image is removed during the development process (
In step 3), most of the powder is removed from the photoreceptor, and the powder charged to the same polarity as the electrostatic latent image is adsorbed to the exposure attenuation portion of the electrostatic latent image.

In other words, it has been confirmed that the photoreceptor is cleaned at the same time as the electrostatic latent image is developed.

If you think about the reason for this, it will be as follows.

First, in the charging step (1), the photoreceptor is uniformly charged to +Vo. Even if there is a transfer residual powder layer in the exposed area in the post-exposure step (2), as can be seen from the explanation of FIG.
The surface potential of the exposed portion of the photoreceptor has fallen to the exposure residual potential.

On the other hand, in the unexposed area, it is known from the experiment shown in FIG. The surface potential of is +Vo.

Here, approximately V=Vo /2 (0<Ve<Vo)
The surface of the photoreceptor on which the electrostatic latent image was previously formed is darkened by the magnetic brush on the developing sleeve biased to .

Therefore, in the unexposed high voltage portion of the static TtrIa image, an electric field is generated from the photoreceptor toward the developing magnetic brush.

The transfer residual powder in the unexposed area mentioned above is placed in this electric field, and since it is also charged with the same polarity as the charged polarity, it separates from the photoreceptor surface and moves toward the developing magnetic brush. That's what I do. This is the cleaning action of the photoreceptor.

On the other hand, the developer is carried on the developing sleeve by the force of the magnetic field of the magnet roller 2°, and the colored powder in the developer is mixed with the carrier 19! It is charged to a positive polarity through triboelectric charging, and is electrically adsorbed to the carrier surface by Kirelya's mirror image electrostatic charge.

This positively charged colored powder is placed in the electric field directed from the developing sleeve to the photoreceptor, moves from the developing sleeve toward the exposure attenuation section of the photoreceptor, and due to the II image electrostaticization of the base of the photoreceptor, the exposure attenuation occurs. It is electrically attracted to the surface.

That is, the electrostatic latent image is developed. In this manner, in a method of repeatedly using a photoreceptor in an electrophotographic recording apparatus, cleaning of the photoreceptor is performed simultaneously with development.

However, in such a normal method of repeatedly using a photoreceptor, although the transfer residual powder can have the above-mentioned effect when actually printed and recorded, it cannot be completely removed to the extent that it does not pose a problem on the recorded image.

Therefore, in this embodiment, in addition to the above-mentioned two-component developer consisting of a colored powder made of a resin binder and a low-resistance spherical ferrite carrier, a high-resistance carrier is mixed as a third component to enhance the cleaning effect as a cleaning powder. , conducted several experiments. Note that this is the first powder.

Sample I consisting of a styrene-acrylic resin, carbon, and silica charge control agent was used for the rJ color powder toner, or Ni, Ct+ was used for the second powder low-resistance carrier.
Using a sample port of a ferrite carrier containing Zn, we varied the electrical properties, shape, and particle size of the third powder, a high-resistance carrier sample, and observed their effects.

Experiment 1 in Fig. 5 looked at the electrical properties, and the above-mentioned sample port and carrier dynamic resistance measuring device were installed in Fig. 4 (
Shown in a). An drum 480111 with peripheral speed 139 (
The carrier resistance was measured by applying 50 V to the developing sleeve under the following conditions: mm/sec), developing sleeve radial force φ35 mm, rotational speed 150 (7'1) it), and nip width N8 mm or more. In this measuring device, the sample opening is 10B (Ω-cm
) and 108.1010.

Three types of high resistance carriers of 1012 (Ω·Ca+) were used as sample C. These sample ports and C were both spherical in shape and had an average particle diameter of 100 μm. Then, the sample port and the sample C were mixed at a ff1l ratio of 6:4, and 3.5% by weight of colored powder was mixed into this mixed carrier and used as a developer.

Next, a device for examining the cleaning effect is shown in FIG. 4(b).

Similar to the experimental conditions shown in Figure 3 above, the reflection density of the adsorbed powder was set to D.
= 1.3, and the reflection density was measured after charging → development → static electricity removal while adsorbed. In other words, we have seen the cleaning effect of the magnetic brush. This result is 101 as shown in Figure 5.
The cleaning effect becomes remarkable when the sample C is 0 (Ω.cm).

In other words, the electrical properties of the cleaning effect are approximately 1010 (
A third powder, a high resistance carrier, having a resistance value of Ω·Cl1l) is preferred.

Next, in Experiment 2, the shape of the carrier was examined.

In addition to the aforementioned spherical ferrite carrier with a resistance value of about 1010 (Ω cm), irregularly shaped iron oxide powder carriers having a similar resistance value were added with average particle diameters of 70 μm and 100 μm, respectively.
, 150μ-(all resistance values are 1010(Ω・cn
+) ) was examined again using the examination apparatus shown in FIG. 4(b) described above.

As shown in Figure 6, the cleaning effect of irregularly shaped samples is higher than that of spherical samples.
It was found that particles having a particle diameter of m have extremely high cleaning effects. Therefore, from the above, the resistance value is 1010 (Ω・cm)
It has been found that a carrier of amorphous iron oxide powder with a phase particle size of 70 μm is preferred.

Here, the effect that can be expected by mixing a high-resistance carrier will be explained with reference to Figure 7.The colored powder adsorbed to the sample, which is a high-resistance carrier, is partially located at the boundary of the latent image, as shown in 8 in the figure. (edge part), and some other colored powders are C
It is adsorbed onto the developing sleeve like this. These colored powders! Due to I desorption, a charge of polarity opposite to that of the colored powder is generated locally on the surface 24
However, these remaining charges are difficult to discharge unless they are allowed to leak onto the surface of the developing sleeve.

Therefore, when repeating the photoreceptor, the high resistance carrier (sample c)
The transfer residual powder is guided by the opposite polarity charge 24 on the surface
It is adsorbed onto the surface of the high-resistance carrier (sample C) and cleaned. During this cleaning, the electrostatic latent image is simultaneously developed due to the aforementioned electrode effect by the low resistance carrier shown in FIG. 8 (sample opening).

As mentioned above, in actual electrophotographic equipment, the transfer efficiency is about 80%, and the amount of powder remaining after transfer is only 20%.
Because it is weak, it is possible to completely remove the powder remaining after transfer.

By thoroughly cleaning the photoreceptor at the same time as the above-mentioned development, the powder remaining after transfer will be transferred to the transfer member during the transfer process, and no background fog or background smear will occur in the printed image.

Moreover, this embodiment electrically removes the transfer residual particles from the photoreceptor, so unlike the photoreceptor cleaning method that uses a special cleaning device consisting of a cleaning blade, fur brush, etc., there is no mechanical damage to the photoreceptor and film forming. Not only does it not cause any negative effects such as, but also because the cleaning means itself is removed from the electrophotographic apparatus, it is also possible to make the apparatus more compact.

Next, the stopping operation of each element of the apparatus at the end of printing one sheet will be described.

Figure 9 shows the 0N-O of each component of the image forming process for one sheet printing and the drum static elimination process after the R final printing.
This shows the timing of FF.

When the image creation process for one sheet printing is completed, that is, one
When the lightning for printing one sheet stops, the charger is turned off with a slight delay.
The developing bias is turned off when θ+/W seconds have passed since - has been turned off, that is, when the rear end of the charged portion reaches the developing sleeve position. Here, 01 is the phase difference between the charge changer and the developing roller.

Therefore, the photoreceptor does not continue to rotate any further and no image is developed on the photoreceptor. Seventeen seconds after (θ3+θ1)/W seconds have passed, the transfer of the developed image for one sheet is completed, so the transfer charger 23 is turned off. Here θ3
is the phase difference between the developing section and the transfer charge V.

However, the photoreceptor 2 continues to rotate, and at least θ3/
The paper static elimination charger 12 is kept on for W seconds or more, and the motor and the static elimination lamp are turned off only after θ2/W seconds or more have elapsed since the paper static elimination charger 12 was turned off. In this final drum static elimination process, the photoreceptor is Φ
Since it has an electric charge, the electric charge is completely removed, and image deterioration factors such as image blur caused by the residual electric charge are eliminated.

Furthermore, the motor charging charger and static elimination lamp are turned on almost simultaneously with the next printing command, but the developing bias is
Since the charged portion of the photoreceptor is not turned on until it reaches the developing portion, and therefore the development bias is applied to the uncharged portion, no area other than the image Φ image area is developed.

In other words, in this example, since image formation is not performed in areas other than the image forming area both at the start of application and at the end of printing, an excessive powder layer is not formed on the photoreceptor that has passed the transfer process, and the next This is why the printed image is said to be good because it does not adversely affect the printing process.

In this embodiment, the special cleaning device is removed and the conveyance path of the transfer member is L-shaped so as to surround the photoreceptor with respect to the traveling direction, as shown in FIG. is located diagonally above the photoreceptor, and the transfer member is to be stacked within the paper discharge section.

In this way, the insertion direction of the transfer member P and its storage section into the device, the processing direction of the transfer member ejected outside the device, and the content discrimination and reading direction become the same, and system equipment such as a word processor It also has an ideal shape as a component.

[Effects of the Invention] As explained above, the present invention performs magnetic brush development using a developer made by mixing a developing powder and a cleaning powder as powder other than toner in a developing device.
It is possible to prevent background fogging, background smearing, and ghost images that occur on the image carrier.

Therefore, it is no longer necessary to install a cleaning device, which was conventionally required to be provided in addition to the developing device, and the entire image forming apparatus can be downsized by the space dedicated to the cleaning device.

Further, since a cleaning device is not required at all, problems such as damage to the image carrier and film forming caused by the cleaning device can be prevented.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an electrophotographic recording apparatus to which the image forming apparatus of the present invention is applied, and FIG. 2 shows a configuration for determining charge injection characteristics to the drum surface through a single layer of toner and its charge injection characteristic curve. Figure 3 is a diagram showing the drum exposure characteristics via residual toner, Figure 4 is a diagram showing the configuration of the carrier resistance measuring device and magnetic brush examination device, and Figure 5 is the cleaning effect characteristics of cleaning powder. Figure 6 is a diagram showing the cleaning effect due to particle diameter changes of high-resistance carriers, Figure 7 is a diagram schematically showing the cleaning action of cleaning powder, and Figure 8 is a diagram showing the cleaning effect of a low-resistance carrier. A diagram schematically showing the electrode effect, FIG. 9 is a timing chart of the device shown in FIG. 1, FIG. 10 is a cross-sectional view of an electrophotographic recording device to which a conventional image forming device is applied, and FIG. 11 is a diagram showing the timing chart of the device shown in FIG. 1. A diagram showing the regular development process, Figure 12 is 2
Figure 13 showing a reversal development process using a component developer.
The figure shows the reversal development process using one-component development @ chemicals.
FIG. 14 is a diagram showing a process of repeatedly using a photoreceptor with two revolutions and one recording. 1... Housing of electrophotographic recording device 2... Photoreceptor for electrophotography 3... Fe2 lens 4... Polygon mirror 5
...Developer 6...Charging machine V-jar 7...
・Static elimination lamp 8...Transfer member storage container 9...
・Paper feed roller 10...Align roller 11...
・Transfer charger 12...Paper static elimination charger 13...Fuser 14...Paper discharge roller 15・
... Recording paper storage squirrel 16... Conventional cleaning device 17... Cleaning blade 18... Laser beam 19... Developing sleeve 20... Magnet 21... Conventional developer 22 ... Developer according to this embodiment 23 ... Laser scan motor 24 ... Fixer front guide A ... Transfer residual powder 3 ... Developed four-color powder C ... Development sleeve adhesion D. ...Recorded image E...Electric charge due to detachment of colored powder A...Colored powder mouth...Low resistance carrier...
・High resistance carrier Figure 1 Potential (V) measured by surface electrometer (Figure 2)
igJ-Hiiragi Kyoban! 1 Saku 1 Eye 2 Go L To Rule Edit Umame Fusakaki Ken-Scolding = Leprosy No. 10 Figure 12 ff Figure 13 Figure 14 Procedure Correction Writing Method〉 '7,? / Director General of the Japan Patent Office for the year 1986, Michibe Uga 3, Relationship with the person making the amendment Patent applicant address (residence) 72 Horiyo-cho, Saiwai-ku, Yosaki City, Kanagawa Prefecture Name (307) ) Toshiba Corporation Representative Watarisugi Part 4 Address of agent 1-2-3 Toranomon, Minato-ku, Tokyo 105
No. Toranomon No. 5 Building 5th Floor 6, drawing to be corrected 7, content of correction drawing 10 will be corrected as shown in the attached sheet. (No change in content) 8. Attached document catalog drawings Figure 10 and above Procedures Neho Seiguchi (Voluntary) November 1985? Japan Patent Office Commissioner Kuro 1) Mr. Akio 1, Indication of the case Patent Application No. 68410 of 1988 2, Title of the invention Image forming device 3, Person making the amendment Relationship to the case Patent applicant address (residence) 72 Horiyo-cho, Saiwai-ku, Yozaki City, Kanagawa Prefecture Name (307) Toshiba Corporation Representative Watari Sugi-bu (and 1 other person) 4. Agent address 1-chome Toranomon, Minato-ku, Tokyo 105 2nd 3
Toranomon No. 1 Building 5th Floor 6, "Detailed Description of the Invention" column 7 of the specification to be amended, contents of the amendment as attached attached (1) "Charger" on page 3, line 4 of the specification,
"Charger" I corrected. (2) "Bias" on page 5, line 13 of the same book is corrected to "bias." (3) In the 13th line of page 13 of Domon, the statement ``20 is...a magnet'' is corrected to ``20 is a magnet.'' (4) The same book, page 13, line 16, “60oIIIT
Correct it as ``l'', r60mmJ. (5) "Charger" written in the first, fourth, and eighth lines of page 14 of the same gate is corrected to "Charger." (6) “Charger” on page 19, line 6 of the same gate,
"Charger" I corrected. (7) "Charger" in lines 19 and 20 of page 26 of the same book is corrected to "charger." (8) "Charger" in lines 13 and 20 of page 27 of the same book is corrected to "charger."that's all

Claims (4)

[Claims] (1) In an image forming apparatus that simultaneously performs a developing step and a cleaning step using a developing device that makes a latent image formed on an image carrier visible, the developing device uses a developing powder and a cleaning powder as powders other than toner. An image forming apparatus characterized in that magnetic brush development is performed using a developer made of a mixture of the following. (2) The image forming apparatus according to claim 1, wherein in the developer, the developing powder is a low-resistance magnetic carrier, and the cleaning powder is a high-resistance magnetic carrier. (3) The image forming apparatus according to claim 1 or 2, wherein the developing powder of the developer is a spherical magnetic carrier, and the cleaning carrier is an amorphous magnetic carrier. (4) The image forming apparatus according to claim 1 or 2, wherein in the developer, the cleaning carrier has an average particle diameter of 100 μm or less.