JPH0518111B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for converting electrical image information that is calculated or read out from a computer or image reading device, or image information stored on a magnetic tape or microfilm into a visually recognizable image. The present invention relates to an image forming apparatus used in a reproduction apparatus or a copying machine for further obtaining a hard copy thereof, and particularly relates to an apparatus for forming a toner image on the surface of an image carrier.

Conventionally, the following methods have been known as simple methods for forming toner images on the surface of an image carrier.

In one method, as shown in FIG. 1, a photosensitive layer 1 is provided on a transparent conductive substrate in which a transparent conductive layer 2 and a transparent support 3 are laminated to form a photoreceptor. Then, a direct current bias is applied by a power source 4 between the toner carrier 5, on which a conductive magnetic developer (hereinafter referred to as toner) 6 is uniformly adhered by the magnetic field generating means 5a, and the substrate of the photoreceptor. Apply. This creates a uniform potential difference between the developer and the surface of the photoreceptor. Then, by performing image exposure P from the transparent conductive substrate side of the photoreceptor at a position where the conductive toner 6 on the toner carrier is guided to the surface of the photoreceptor,
This method forms a toner image in the form of an image pattern on the surface of a photoreceptor. For example, if we consider the process of depositing toner on the surface of an N-type photoreceptor, as shown in FIG. With a DC bias applied from a power source 4, conductive magnetic toner 6 is introduced onto the surface of the photoreceptor. Then, a uniform potential difference is formed between this toner and the surface of the photoreceptor,
At the same time, image light is irradiated from the transparent conductive substrate side. As a result, according to the photo carriers 8 generated and moved in an image pattern in the photosensitive layer 1, a positive charge 7 is applied to the conductive toner 6 held on the toner carrier.
is induced, and the toner 6 is deposited on the surface of the photoreceptor by the Coulomb force as shown in FIG.

Note that although the above explanation uses an N-type photoreceptor as an example, similar results can be obtained even if other photoreceptors are used by selecting the polarity of the DC bias applied between the toner carrier and the transparent conductive substrate. Furthermore, a method has also been proposed in which a high resistance layer having an appropriate time constant is provided on the conductive layer to further sharpen the formed toner image.

FIG. 4 shows a format in which the image light in the above example is provided by a signal-modulated laser beam, in which 5a is a magnetic field generating means, 14 is a polygon mirror, 15 is an f-theta lens, and 16 is an optical path folding device. Shows a mirror for.

The following method is also known as another simple method for forming an image as a toner image. That is, a toner having conductivity and magnetism, a toner carrier having a conductive or non-conductive surface and having a magnetic field generating means disposed therein, and a toner carrier which is electrically insulated from the toner carrier and which has an electric charge on the toner. a plurality of recording electrodes arranged in parallel on the toner carrier, an image carrier having a charge retention ability, and an opposing electrode with the image carrier at the recording electrode arrangement position sandwiched therebetween; A counter electrode placed at the same position is used. Then, the toner is conveyed onto the recording electrode by the magnetic force of the magnetic field generating means, and a bias is selectively applied between the opposing electrode and the recording electrode according to the recording signal, so that the toner is transferred to the surface of the image carrier. This method forms an image using toner.

As another form similar to this method, a toner carrier having conductive and magnetic toner, a toner carrier having a conductive or non-conductive surface in which a magnetic field generating means is disposed, and an electric charge being supplied to the toner. a counter electrode having a function and disposed on the toner carrier, an image carrier having a charge retention ability, and a plurality of recording electrodes disposed in parallel at opposing positions with the image carrier at the counter electrode position sandwiched therebetween; Use. Then, the toner is conveyed onto the recording electrode by the magnetic force of the magnetic field generating means, and a bias is applied to the opposing electrode and the recording electrode according to the recording signal to cause the toner to adhere to the surface of the image carrier, thereby forming an image using the toner. There are also ways to do it.

FIG. 5 shows a schematic configuration of an example of an apparatus according to these image forming methods, and is specifically a schematic diagram of the apparatus described in US Pat. No. 3,816,840. In the figure, 20 is a thin-layer insulating image carrier, 21 is a conductive toner carrier, and a magnet 22, which is an internal magnetic field generating means, rotates in the direction of the arrow to rotate the conductive magnetic material on the toner carrier. toner 24
is being conveyed in the direction of arrow 25. Reference numeral 23 denotes a recording electrode arranged on the opposite side of the image carrier, facing the contact position of the toner to the image carrier, and having a large number of independent electrodes arranged in the width direction of the image carrier. A power source E is provided so that a voltage can be selectively applied between the plurality of recording electrodes and predetermined electrodes of the conductive sleeve 21.

FIG. 6 briefly shows the process of forming a toner image on an image carrier by the method described above.

When the switch 26 is connected to the contact on the power supply E side,
A voltage is applied by a power source E between the conductive toner carrier 21 serving as a counter electrode and the recording electrode 23 corresponding to the predetermined switch. As a result,
A closed circuit consisting of the conductive toner 24→toner carrier 21→ground→power supply E→switch 26→recording electrode 23→image carrier 20 is formed. In this circuit, due to the capacitance in the image carrier 20, charges are almost instantaneously accumulated at the tip of the conductive toner 24 closest to the recording electrode 23 and at the tip of the recording electrode 23, and these charges are Coulomb force acts between them. And image carrier 2
0 is pulled away from the brush formed by the toner, by applying the Coulomb force stronger than the magnetic force applied to the magnetic toner on which the electric charge has been accumulated by the magnet inside the toner carrier 21, the magnetic force is applied to the image carrier 20. ON-OFF of switch 26
It is possible to form a toner image according to the conditions.

As shown in FIG. 7, the recording electrodes 23 constitute an array by arranging a plurality of recording electrodes 23 in parallel and insulated in a direction substantially perpendicular to the moving direction of the image carrier 20. Then, a voltage is selectively applied between the recording electrode and the image carrier 20 by a driver (driving circuit) 27 (circuit details not shown), and toner is deposited on the image carrier 20. It is now possible to form a toner image.

FIG. 8 is a schematic diagram of an image forming method described in US Pat. No. 3,879,737. In this example as well, the switch 26 is
By connecting to the power supply E, a closed circuit consisting of the conductive toner 24 → recording electrode 30 → switch 26 → power supply E → counter electrode 31 → image carrier 20 is constructed. In this circuit, due to the capacitance in the image carrier 20, charges are almost instantaneously applied to the tip of the conductive toner 24 on the recording electrode 30 that is closest to the counter electrode 31, and to the tip of the counter electrode 31. Accumulated. A Coulomb force acts between these charges, and at the time when the image carrier 20 is separated from the brush formed by the toner, a magnetic force is applied to the conductive magnetic toner in which the charges have been accumulated by the magnet inside the toner carrier 21a. than,
By applying a strong Coulomb force, a toner image can be formed on the image carrier 20 according to the ON/OFF state of the switch 26. Further, as described in FIG. 7 above, a plurality of electrically independent recording electrodes 30 are arranged in parallel in the width direction of the image carrier 20 in a direction substantially perpendicular to the moving direction of the image carrier 20. to configure the array. Then, by selectively applying a signal voltage to each signal electrode by a driver (drive circuit), the counter electrode 31
By applying a voltage between them, toner can be selectively deposited onto the image carrier 20 to form an arbitrary toner image.

The image forming method described above uses a conductive toner and an image carrier (including the photoreceptor described in FIGS. 1 to 4).
By applying a voltage between a pair of electrodes that are arranged opposite to each other so as to be sandwiched between them, an image using toner is formed on the image carrier. The "pair of electrodes" here refers to the conductive surface of the developing sleeve and its opposing electrode (if this opposing electrode is a transparent electrode as shown in Figures 1 to 4, and as shown in Figures 5 to 7). (including the case of a plurality of recording electrodes arranged in parallel as shown in FIG. (if indicated).

By the way, the image forming method as described above can be said to have a feature in that it does not particularly require a cleaning step for removing toner from the surface of the image carrier when the image carrier is used repeatedly.

The reason for this is that when image formation is performed repeatedly, it is thought that among the toner adhered to the surface of the image carrier, the toner in the area that is not the image area during the next image formation is easily removed from the image carrier by magnetic force. It is. However, when the magnetic force applied to the toner on the image carrier is weak,
In some cases, a so-called cleaning failure may occur when the previously adhered toner cannot be removed, so in order to prevent such cleaning failures, strict requirements regarding design and manufacturing precision must be met. It was hot.

To explain this in more detail, the strength of the magnetic force near the contact area between the image carrier and the toner is
It is determined by the distance between the image carrier and the magnet on the toner carrier side, the strength of the magnetic force of the magnet itself, the number of poles of the magnet, etc. Therefore, as mentioned above, in order to ensure that the developer on the surface of the image carrier can be removed reliably and easily by magnetic force, the setting range and conditions such as the distance between the magnet or the image carrier and the magnet must be adjusted. This is strictly required, and it is also necessary that the surface of the image carrier used has extremely high smoothness.

In view of these points, an object of the present invention is to obtain a clear toner image in which cleaning defects are reliably removed in the above-mentioned image forming apparatus, and further to alleviate the requirements for designing and manufacturing the apparatus. The present invention provides an image forming apparatus with the following features.

To achieve this object, the present invention provides a movable image carrier, and a toner that supports conductive magnetic toner on its surface by magnetic force and conveys and supplies the toner to an adjacent surface of the image carrier. a first toner carrier for removing residual toner on the image carrier and for eliminating static electricity, which is disposed on the upstream side of movement of the image carrier at or near the surface of the toner carrier facing the image carrier; an electrode, a second electrode for image recording located on the downstream side, and an electrode facing the first and second electrodes on the back side of the image carrier, and facing the first electrode. The first electrode and the second electrode are configured to maintain substantially the same potential between the two electrodes, and to generate a potential difference between the second electrode and the opposing electrode. The image forming apparatus is characterized in that the image forming apparatus is disposed facing the image carrier at a position close to the image carrier on the carrier.

In the above configuration, the first electrode and the second electrode are disposed facing each other at a position close to the image carrier on the toner carrier, which means that the first electrode is structurally integrated with the toner carrier. This does not mean that there is a limited structure. It may be structurally separate from the toner carrier as long as it is effective for removing residual toner on the image carrier and eliminating static electricity.

The present invention will be described below based on embodiments shown in the drawings from FIG. 9 onwards.

In FIG. 9, 32 is a developing sleeve that is a toner carrier, and in this example, it is made of a material such as conductive non-magnetic stainless steel (SUS) (or a material that exhibits some magnetism), and is further electrically grounded. It is set up to do so.

Reference numeral 33 denotes a magnet built into the developing sleeve 32.
The developing sleeve 32 is rotated in the 3' direction, and the toner on the surface of the developing sleeve 32 is conveyed in a direction opposite to the 33' direction.

44 is an image carrier, and the developing sleeve 32
Arrow 37 in the figure shows the position where a prescribed gap is maintained between the
It is provided so that it can be moved in the direction. The structure of this image _carrier 44 _is the same as _that of the photoreceptor _described in _FIG .
The transparent conductive layer 2 as an electrode (containing 5% SnO ₂ ), etc., and the transparent support 3 are designated by the same reference numerals as in FIG.

The feature of this example is that a first electrode is placed on the developing sleeve at a position where the developing sleeve 32 and the image bearing member 44 are close to each other, that is, at a position where toner is supplied and conveyed to the surface of the image bearing member, and on the upstream side of the movement of the image bearing member. 34
Further, a second electrode 35 is provided on the developing sleeve on the downstream side of movement of the image carrier. The first electrode 34 is for erasing the charge of the conductive magnetic toner on the surface of the image carrier, and in this example, the transparent conductive layer 2 of the image carrier 44 is grounded as shown in the figure. Corresponding to the fact that
The first electrode 34 is electrically connected to the developing sleeve 32 and grounded. In addition, the first
The electrode 34 may be directly grounded, and in this case, the developing sleeve 32 may be made non-conductive. On the other hand, the second electrode 35 is used to charge the toner and cause the toner necessary for image formation to adhere to the image carrier 44 using Coulomb force.
It is provided so that it is electrically connected to a power source E and a DC bias is applied thereto. In this example, since the developing sleeve 32 is configured as a conductive member, the developing sleeve 32 and the second electrode 35 are electrically isolated by the insulating layer 36.

Next, the operation in the developing section will be explained with reference to FIG.

The toner 40 on the developing sleeve 32 is conveyed in the direction of arrow 40 by the rotation of magnet 33 in the direction of arrow 33'. As described above, the conductive substrate 2 in the image carrier 44 is grounded, and has the same potential (or approximately the same potential) as the conductive substrate on the upstream side with respect to the relative movement direction 37 of the image carrier 44.
Since the first electrode 34 maintained at
The conductive magnetic toner 40 passing over the electrode is kept at the same potential.

By the way, when the image carrier 44 is used repeatedly, the conductive magnetic material 38 that was developed and adhered to the image carrier 44 from the previous time remains on the image carrier 44, and this residual developer 38 remains.
As already mentioned, there are cases where some charge injected during the previous development remains, and this causes poor cleaning.

However, according to the configuration of the embodiment described above, the first
Since the electrode 34 is kept substantially grounded, it has the effect of almost completely neutralizing the residual charge, and as a result, the electrically neutralized residual toner is transferred to the first electrode 34 by the magnetic force of the magnet 33. It is almost completely peeled off from the image carrier surface in the vicinity.

In the process of neutralizing the charge of the residual toner on the image carrier 44 brought about by the presence of the first electrode 34, the direction of rotation of the magnet 33 is
3' direction, and setting the moving direction of the toner 40 in the direction of arrow 40' is a particularly effective choice. This is because in this state, a toner pool is formed near the first electrode 34, that is, on the upstream side in the moving direction of the image carrier 44, the toner density here is high, and the peeling effect of the remaining toner becomes even stronger.

In addition to the cleaning effect, the presence of the first electrode 34 also has the advantage of preventing unnecessary frictional electrification on the surface of the image carrier 44.

Next, the action of the second electrode 35 will be described. This is a component for performing the same development as in the cases shown in FIGS. Since this is the actual development process immediately after the image carrier surface has been almost completely cleaned and antistatically charged by the electrodes, it is characterized by the ability to form extremely clear images.

The best position for the second electrode 35 is to provide it at a position facing the image exposure P, and furthermore, to provide it on the line connecting the closest portion of the image carrier 44 and the developing sleeve 32 (indicated by 41 in the figure). The best image can be obtained by doing this, but even if a slight deviation is made on the upstream or downstream side of the movement of the image carrier 44 from the line 41, as long as the image quality can be obtained without any practical problems. good.

Next, regarding the arrangement relationship between the first electrode 34 and the second electrode 35 which are adjacent to each other, the distance between them, that is, the gap x (see FIG. 11) is as follows.
It must ensure electrical insulation between both electrodes. A problem with this insulation is leakage via the conductive magnetic toner, but as is well known, the magnetic toner 40 is caused to leak onto the developing sleeve 32 by the action of the magnet 33 as shown in FIG. The electrical resistance is low in the direction in which the ears stand, but the resistance is at least two orders of magnitude higher in the direction substantially perpendicular to this direction. Therefore, by appropriately selecting the gap between the first electrode and the second electrode, the influence of leakage via toner between these two electrodes can be almost ignored. Generally, with an insulator (or one with sufficiently high resistance) interposed between the two electrodes, the gap x is at least 0.5
It is desirable that the diameter be at least mm.

Note that providing the gap x in the developing section does not impose any particular restrictions on electrode arrangement. That is,
For example, if a developing sleeve with a diameter of 32 mm is used, the contact width of the image carrier 44 with the toner 40 is 10 mm on the upstream side from the closest portion shown in FIG.
mm, and about 3 mm can be secured on the downstream side, whereas the gap between the first electrode and the second electrode is so small that its effect on the action during development can be ignored. This is because

As described above, a clear image (toner 39
) is obtained.

Although the present invention is concretely realized by the embodiments shown in FIGS. 9 to 12 described above, the present invention is not limited thereto, and various modified embodiments may be implemented. Examples can be considered.

The embodiment shown in FIGS. 13a and 13b is the embodiment shown in FIGS.
This type is a modified version of the one in FIG. 12, in which magnetic materials 42 and 43 are provided in the first electrode 34 and second electrode 35, respectively (or the electrodes 34 and 35 themselves are formed of magnetic materials). By arranging the magnetic bodies 42 and 43 as in this example, it is possible to form stable spikes of conductive toner 40 on the magnetic body. On the first electrode 34, the above-mentioned cleaning action or the image carrier 44
The antistatic effect on the surface becomes even more reliable. That is, as shown in FIG.
the first electrode 34
The magnetic body 42 receives a strong magnetic force and forms a tall spike. For this reason, the electrical paths in the direction of the spikes with low electrical resistance become dense between the surface of the image carrier 44 and the first electrode 34 (including the magnetic material 42), as described above. The effect of neutralizing the residual charge and preventing the surface of the image bearing member from being charged is greatly obtained, and furthermore, since the toner density is high, the effect of removing the residual toner is even greater. In addition, even in the magnetic material 43 of the second electrode 35, a voltage can be applied at the contact portion between the stable spike and the image carrier 44 to provide image exposure P, so that the image is sufficiently sharp without unevenness. Good images can be obtained. Furthermore, the effect of providing the magnetic bodies 42 and 43 further ensures the prevention of leakage in the gap between the first electrode 34 and the second electrode 35 described above. That is, since the magnetic flux is concentrated in the magnetic bodies 42 and 43, the density of the conductive magnetic developer in the gap can be made sufficiently small.

Note that since the above-mentioned magnetic bodies 42 and 43 each have the above-described effects independently, they may be provided only in the first electrode 34 or only in the second electrode 35 depending on the case. It may be provided.

In the former case, it is desirable that the image exposure P and the second electrode be located near the closest point between the image carrier 44 and the developing sleeve 32.

In the latter case, it is effective to apply the image exposure P at the contact portion of the toner, which stands up in spikes due to the magnetic material, with the image carrier.

In the embodiments of the present invention described above, the image carrier 44 is, for example, one in which a transparent conductive layer is provided on a transparent mylar film (for example, manufactured by Daicel Chemical Co., Ltd.).
CELEK (transparent conductive film) sensitized CdS,
A photoreceptor can be used as a photosensitive layer by coating ZnO etc. dispersed in a binder.
Alternatively, a photoreceptor surface layer may be provided by further coating TiO ₂ or the like dispersed in a binder on the photoreceptor layer.

In each of the embodiments shown in FIGS. 9 to 12 and 13, the image exposure P may be provided by scanning a signal-modulated gas laser or semiconductor laser with a polygon scanner. However, modulated light using an LED array or liquid crystal shutter array may also be used. Alternatively, the illuminating light for the document may be applied through a slit like in a normal copying machine. The developing sleeve 32 is as described above.
Non-magnetic SUS does not slip on the surface and is advantageous in conveying the developer. The insulator 36 may be made of mylar or the like. The magnetic material 42 or 4 described above
3 is desirably a belt-like material having a width of about 0.5 mm to 5 mm and extending in the longitudinal direction of the developing sleeve 32.

As the conductive magnetic toner, one having a volume resistivity of 10 ¹³ Ω·cm or less, preferably about 10 ³ to ^{10 10} Ω·cm can be used. For the second electrode 35, 50V to the conductive substrate 2 of the photoreceptor.
It is optimal to apply a DC voltage of 500V.

Further, in the above embodiment, the toner is conveyed in the same direction as the moving direction of the image carrier, but the toner may be conveyed in the opposite direction.

FIG. 14 shows another embodiment of the invention, in which a voltage is applied to the second electrode 35' through the conductive developer sleeve 32', while the first
The electrode 34' is formed using a conductive thin wire such as a corona wire.

In the case of this example, it is possible to bring the first electrode 34' closer to the surface of the image carrier, and the above-mentioned cleaning action or antistatic action can be performed more efficiently. Also in this example, the first electrode 34' is made of a magnetic material or the second electrode 34' is made of a magnetic material.
It is possible to provide a magnetic material in the electrode 35 as well, and the effect is great.

The embodiment shown in FIGS. 15 and 16 corresponds to an improved version of the image forming apparatus shown in FIG. This is an image carrier provided with a layer 46, and electrostatic recording paper or the like is generally used. 4
7 is a first electrode for toner cleaning, and 48 is a second electrode consisting of a plurality of signal electrodes to which voltages related to development are applied. 50 again
is the second electrode, that is, the plurality of signal electrodes 48a, 4
8b, ... are each made independent and the driver 49
It is an insulator for connecting to a circuit and for electrically isolating the first electrode 47. In this example, the number of second electrodes 48a, 48b, . . . is usually 10 pieces/mm.
Developing sleeve 3 at a density of
placed in parallel to the insulators 50 on 2″, each 10
A toner image is formed on the image carrier 51 based on selective application of a voltage of about 100 V to 100 V.
In this case, the action of the first electrode 47 is the same as that described above as a cleaning action or an antistatic action, but in this example in particular, when the image carrier 51 is repeatedly used, the surface of the image carrier 51 becomes high. Since the insulating layer 46 is used, there are many cases in which charge remains in the toner remaining from the previous time, and neutralization of the remaining charge by the first electrode 47 has a great effect in forming a clear image. bring. In addition, one of the characteristics of this example is that by providing a magnetic material part of the first electrode or by configuring the first electrode itself from a magnetic material, it is possible to In addition, leakage between the first electrodes formed as multiple signal electrodes arranged in parallel can be effectively prevented.

As described above, according to the present invention, it is possible to reliably prevent cleaning defects and obtain clear image formation with sufficient toner provided for image formation by the second electrode. This has the effect that it is possible to provide a stable image forming apparatus by significantly relaxing the apparatus setting conditions for forming such a clear image, and furthermore, it is possible to provide a stable image forming apparatus by using the same toner carrier as the first electrode and the second electrode. The configuration in which electrodes with separate functions are placed on the top of the image carrier and facing each other in the vicinity has the effect of providing a compact device that takes up less space, and its usefulness is There is something very big.

[Brief explanation of the drawing]

The drawings are for explaining the present invention, and FIGS. 1 to 8 show the configuration of a conventional image forming apparatus,
Figure 1 is a diagram showing the configuration of the main parts of the image exposure format.
Figures 2 and 3 are diagrams explaining the process of image formation, Figure 4 is a diagram showing the configuration of the main part of a system that provides image light using a laser beam, and Figures 5, 6, and 8 are diagrams that illustrate the image formation process. FIG. 7 is a partial perspective view of the image forming apparatus shown in FIG. 6. Figure 9 ~ 1st
6 is a diagram for explaining an embodiment of the present invention, FIG. 9 is a diagram showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention, FIG. 10 is a partially enlarged view thereof, and FIG. The figure is a partial perspective view of the electrode portion, and FIG. 12 is a diagram illustrating the state of toner spikes. FIGS. 13a and 13b are diagrams showing modifications of the embodiment shown in FIGS. 9 to 12. FIG. 14 is a schematic diagram of the configuration of an image forming apparatus showing another embodiment of the present invention, and FIGS. 15 and 16 are diagrams showing still other embodiments. DESCRIPTION OF SYMBOLS 1... Photosensitive layer, 2... Transparent conductive layer, 3... Transparent support, 4... Power source, 5... Toner carrier, 6...
...Toner, 5a...Magnetic field generating means, 7, 9, 10
...Charge, 8...Photo carrier, 14...Polygon mirror, 15...F-θ lens, 16...Mirror, 20...Image carrier, 21, 21a...Toner carrier, 22...Magnet, 23,30...
Recording electrode, 24... Conductive magnetic toner, 26...
...Switch, 27...Driver, 31...Counter electrode, 32, 32', 32''...Developing sleeve (toner carrier), 33...Magnet, 34,3
4'...First electrode, 35, 35'... Second electrode, 36... Insulator, 38, 39, 40... Toner, 42, 43... Magnetic material, 44... Image carrier,
45... Conductive base, 46... Insulating layer, 47... First electrode, 48... Second electrode, 49... Driver circuit, 50... Insulator, 51... Image carrier.

Claims (1)

[Claims] 1. An image carrier to be moved, a toner carrier that carries conductive magnetic toner on its surface by magnetic force and conveys the toner to a surface adjacent to the image carrier, and an image carrier of the toner carrier. On the opposing surfaces or in the vicinity thereof, a first electrode for removing residual toner and static electricity on the image carrier is disposed on the upstream side of the movement of the image carrier, and a first electrode for image recording is located on the downstream side. and an electrode facing the first and second electrodes on the back side of the image carrier, the first electrode and the facing electrode being held at approximately the same potential, and , the second electrode and the opposing electrode are configured to generate a potential difference, and the first electrode and the second electrode are arranged on the same toner carrier at a position close to the image carrier side. An image forming apparatus characterized in that the image forming apparatus is disposed facing an image carrier.