JPH01277268A - Image forming device - Google Patents

Abstract

PURPOSE:To suppress a transfer roller from being stained by setting the width of the image forming layer of an image holding body larger than that of a transfer part consisting of a rotating body for transfer. CONSTITUTION:A photosensitive layer 1b that is the image forming layer is formed with the width H1 larger than the width of the length of the transfer roller 12 that is the rotating body for transfer, that is, the width 1 of the transfer part for the circumferential plane of a cylinder 1a as the photosensitive layer supporting body of a drum type photosensitive material 1. Therefore, no developer is attached on the photosensitive layer 1b by performing primary electrification in a range larger than the width I of the transfer roller. Also, cleaning by a cleaning device 6 can be performed in the range larger than the width I of the transfer roller. In such a way, it is possible to suppress the stain of the transfer roller.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an image forming apparatus.

More specifically, a target image is formed on the image forming layer surface by relatively moving an image carrier having an image forming layer on the support material surface and an image forming means, and the formed image is transferred onto the transfer material surface. The image forming means includes an electrostatic latent image forming process means including a charging means for uniformly applying a charge to the surface of the image forming layer of the image carrier, and a developing means for making the latent image visible with a developer. ,
The present invention relates to an image forming apparatus having a transfer rotating body (transfer roller, transfer belt, etc.) that transfers images onto the surface of the visible transfer material.

(Prior Art) Specific examples of the above-mentioned image forming apparatuses include copying machines, printers, microfilm reader printers, display devices, etc. that utilize transfer-based electrophotography and electrostatic recording. All are widely used.

Generally, an electrophotographic photoreceptor or electrostatic recording dielectric material as an image carrier is formed into a drum or belt that is driven to rotate or rotate at a predetermined circumferential speed, and is driven to rotate or rotate. The drum or belt is uniformly charged positively or negatively using a corona discharger, contact charger, or other charging means, and the electrical charge is selectively removed using slit exposure, laser beam scanning exposure, light emitting element array, static eliminator array, etc. The electrostatic latent image corresponding to the image information is formed by removing static electricity or by charging it with a reverse polarity.The latent image is developed using a developer using a developing means, and the developed image is transferred to a transfer material (a second image). The image is transferred onto the surface of the second image carrier (generally a transfer sheet material mainly made of paper) using a transfer means, and the transfer material that has received the image is fixed with an image by a fixing means and is discharged from the apparatus as an image-formed product. After image transfer, the drum surface or belt surface, which is an image carrier, is cleaned by a cleaning means and then turned over for use in image formation.

FIG. 12 shows a schematic diagram of the configuration of an example of such an image forming apparatus. The apparatus of this example is a laser beam printer (LBP) using a transfer type electrophotographic method.

1 is a drum-shaped electrophotographic photoreceptor (o
PC photoreceptor), which is rotated around a central support shaft 0 in the clockwise direction of arrow a at a predetermined circumferential speed.

As the photoreceptor 1 rotates, its outer peripheral surface is charged with a predetermined polarity (-order charging) by a corona charger 2 serving as a charging means.

Next, a laser beam scanner (not shown) performs laser beam scanning exposure 3 on the surface of the photoreceptor corresponding to image information output from a computer, word processor, etc. (not shown), thereby exposing the surface of the photosensitive belt to an electrostatic latent image of the target image. Images are formed one after another.

The latent image is sequentially developed with developer material (toner) by the developing device 4. Then, the transfer material 11 fed one sheet from a paper feeding mechanism (not shown) is synchronized (timed) with the rotation angle of the photoconductor 1 at a predetermined time by a pair of registration rollers 8, and then the transfer material 11 is transferred to the photoconductor 1 and the transfer charger 5. The developer image on the photoreceptor 1 side is sequentially transferred onto the surface of the transfer material 11. The transfer material on which the image has been transferred is separated from the surface of the photoreceptor 1 and introduced into the fixing device 9, where the image is fixed and output as an image-formed product (print) outside the premises. 10 is a conveyance guide for the transfer material.

After the image transfer, the surface of the photoreceptor is cleaned by a cleaning device 6 to collect and remove residual developer, and is also cleaned by a surface exposure device 7.
The entire surface is exposed to light, the charge is uniformly removed from each part, the electrical memory is erased, and the image is repeatedly formed.

A developed image (
As an image transfer means for transferring the developer image to the surface of the transfer material, a transfer charger 5 is generally used as shown in the apparatus shown in FIG. 12 described above. This is the image carrier 1 that carries the developer image.
The developer image on the image carrier side is transferred by feeding the transfer material 11 to the surface of the transfer material and applying a charge having a polarity opposite to that of the developer image on the image carrier surface side by corona discharge to the back surface of the transfer material. The transfer material is transferred and adsorbed (transferred) to the side facing the image carrier by electrostatic attraction, and has the advantage of being simple in structure and relatively stable transfer performance.

However, on the other hand, during transfer, the developer may scatter around the transferred characters due to the influence of excessive backside charge applied to the back surface of the transfer material. During transfer, the transfer material 11 contacts the surface of the image carrier only by electrostatic force. Therefore, there is a drawback that transfer misalignment may occur when the transfer material 11 comes off from the registration roller 8 of the image forming apparatus shown in FIG. there were.

On the other hand, there is a transfer roller device as another type of transfer device that solves the drawbacks of such a transfer charger. This is the seventh
As shown in the example in Figures 8 and 9, the transfer material 11 is fed to the surface of the image carrier 1 carrying the developer image ta, and the developer image ta on the side of the image carrier 1 is placed on the back side of the transfer material. The image transfer tb is performed by applying the transfer material 11 to the surface of the image carrier by pressing an elastic transfer roller 12 to which a voltage (including ground) having a polarity different from the charge e of the developer is applied. Compared to the case using the transfer charger 5 described above, excessive backside charge is not applied to the back surface of the transfer material, so there is almost no scattering of developer around the transferred characters, and high image quality can be achieved. (13 indicates a bias power supply). In particular, in an image forming apparatus using a reversal development method, the latent image charge e2 on the image carrier surface is
Since the charge e of the developer of the developer image t6 and the charge e of the developer of the developer image t6 have the same polarity, the bias 't [pressure applied to the transfer roller 12 is required to be small, and the advantage is that it is easy to obtain a good transferred image tb without developer scattering. There is.

Also, during transfer, the image carrier 1 and the transfer roller 12 transfer the transfer material 1
There is also the advantage that image shift does not occur because transfer and conveyance are performed simultaneously while holding 1.

In FIG. 8, 01, 01, 02-02 are the rotation center axis of the drum-type photoreceptor 1 as an image carrier and the rotation center axis of the transfer roller 12, respectively, and W□8 is the transfer material 11 of the maximum size that can be used. (the dimension in the direction perpendicular to the transfer material conveyance direction), and l indicates the length dimension of the transfer roller 12, that is, the width dimension of the transfer portion. The drum-type photoreceptor 1 has a photoreceptor layer t as an image forming layer on the outer peripheral surface of a conductive material cylinder la, which is generally made of aluminum, as a support material.
b (dielectric layer in electrostatic recording) coated with a predetermined width H, or a sheet-shaped photoreceptor layer 1 formed in advance
b is wound around the outer peripheral surface of the support member 1a and integrated. h is the remaining surface portion of the support material outside both sides in the width direction of the photoreceptor layer 1b.

The width H of the photoreceptor layer ib as an image forming layer is set to the width necessary for image formation or to a width that allows for a slight margin. Also, the transfer material width Wm□ and the transfer part width ■ are generally W,,
, < 1.

(Problems to be Solved by the Invention) As described above, the image forming apparatus configured to have the relationship of transfer material width W, .

(1) Forming the image forming layer 1b on the image bearing member 1 The supporting material 1a supported on the image bearing member 1 has a potential value closest to that of the image forming layer even when it is grounded 14 or a bias is applied. The bias value is smaller than . Therefore, especially in the case of an image forming apparatus that uses a developer having the same polarity as that of the latent image, such as reversal development, the developer scattered (flying) from the developing device 4 and the cleaning device 6 may be thrown onto the image carrier. It tends to adhere to the remaining surface of the support material on the outside of both sides of the image forming layer 1a.

Generally, this surface portion of the support material is not cleaned by the cleaning device 6, so if this surface portion of the support material is contaminated by adhesion of developer, the opposing transfer roller 12 will be contaminated immediately.

The relationship between the width H of the photoreceptor layer 1b and the cleaning width by cleaning play 1<6b of the cleaning device 6 is expressed as follows.
Shown in Figure 0. The cleaning blade 6b is made of urethane or the like, and is oriented counter to the rotating direction of the drum-type photoreceptor 1 as shown in FIG. The transfer residual developer on the surface of the photosensitive belt 1 is scraped off by the tip end portion of the cleaning blade 6b, thereby cleaning the surface of the photosensitive member 1. 6a is a stay for holding the cleaning blade 6b.

Generally, the width of the cleaning blade 6b includes the photoreceptor layer 1b.
is the same as or narrower than the width H of.

The reason for this is that when the width K of the cleaning blade 6b becomes wider than the coating width H of the photoreceptor layer 1b, both ends of the tip end portion of the cleaning plate 6b formed of urethane etc. directly touch the photoreceptor layer supporting material 1a. It comes into contact with the photoreceptor layer non-existent surface portion h-h (metal surface such as aluminum) on both end sides, and the friction coefficient at that contact portion tends to be larger than the friction coefficient in other ranges. In such a case, the cleaning blade 6b may be turned over, and the entire cleaning range may become unable to be cleaned.

Regarding the transfer roller 12, the surface portions L-L on both end sides of the transfer roller other than the portions corresponding to the cleaning processing range of the photoreceptor R1b are photoreceptors! The dirt and scattered developer on the surface are immediately transferred and contaminated.

(2) The transfer roller 12 is generally a conductive or semiconductive elastic roller, and is used with a bias applied thereto. FIG. 11 is an explanatory diagram of the relationship among the photoreceptor 1, transfer roller 12, and current in this case.

The photoreceptor layer support 1a of the photoreceptor 1 is grounded 14.

The transfer roller 12 receives a bias voltage from a power source 13. e is a charge that acts as a transfer current.

When transferring by applying a constant voltage to the transfer roller 12, the photoreceptor layer supporting material 1a of the photoreceptor 1 and the transfer roller 1
2 is in a leaking state, the current from the power supply 13 for transfer increases, resulting in inconveniences such as stained toner burning and damage to the transfer roller.

Furthermore, when transferring with a constant current, the voltage becomes too small for the same reason, and the amount of current flowing in a portion of the transfer material 11 becomes extremely small, making transfer impossible.

The present invention aims to eliminate problems such as (1) and (2) above regarding this type of image forming apparatus that uses a transfer rotating body (transfer roller, transfer belt, etc.) roller as a transfer means. It is something.

(Means for Solving the Problems) The present invention forms a target image on the image forming layer surface by relatively moving an image carrier having an image forming layer on the support material surface and an image forming means, and This is a method of transferring an image onto the surface of a transfer material, and the image forming means includes an electrostatic latent image forming process means including a charging means for uniformly applying electric charge to the surface of the image forming layer of the image carrier, and a method for forming the latent image. In an image forming apparatus having a developing means that develops an image using a developer and a transfer rotary body that transfers the developed image onto a transfer material surface, the structure described in the following item (1) or (2) is provided.
This is an image forming apparatus characterized by the configuration described in item ).

(1) Regarding the image forming layer provided on the support surface of the image carrier, the width dimension of the image forming layer in the direction perpendicular to the direction of relative movement between the image carrier and the image forming means is measured at the transfer portion of the image carrier surface by the transfer rotating body. An image forming apparatus characterized in that the width of the transfer section is set to be larger than the width of the transfer section in the direction perpendicular to the direction of relative movement between the image carrier and the transfer rotating body.

(2) An image forming layer is provided on the supporting material surface of the image carrier with a predetermined width dimension in a direction perpendicular to the direction of relative movement between the image carrier and the image forming means, and both sides of the image forming layer in the width direction are provided. An extension material layer made of a material different from that of the image formation layer is provided on the outer side of the support material in series and substantially the same as the image formation layer, and the overall width dimension of the image formation layer and the extension material layer on both sides thereof is is larger than the width of the transfer portion in the direction perpendicular to the direction of relative movement between the image carrier and the transfer rotor with respect to the transfer portion of the surface of the image carrier by the transfer rotor.

(Function) That is, in the configuration of item (1), since the width of the image forming layer of the image carrier is wider than the width of the transfer area by the transfer rotating body, the width of the transfer area is By performing the primary charging by the charging means over a wider width range, there is no developer deposits on the surface of the image forming layer within the width range of the transfer portion that would contaminate the transfer rotary member. Therefore, over the entire length of the transfer rotary member, contamination of the developer from the surface side of the image carrier by the person applying the transfer is substantially eliminated. Furthermore, since the cleaning means can clean the surface of the image carrier over a wider range than the width of the transfer section, it is also possible to suppress developer staining over the entire length of the transfer rotor.

In addition, in the configuration of item (2), the same effects as above can be obtained, and due to the presence of the extension material layer of the image forming layer, the image forming layer itself can be adjusted to the width dimension of the transfer material of the maximum size that can be used (transfer Since the size of the image forming layer is limited to the dimension perpendicular to the material conveyance direction, the amount of expensive image forming layer material used can be minimized, and costs can be reduced.

(Example) Actual hk example 1 (Figs. 1 and 2) Fig. 1 shows the image forming apparatus (LBP) shown in Fig. 7, in which the drum-type photoreceptor 1, which is an image carrier, is prepared according to the present invention. The photoreceptor layer 1b, which is an image forming layer, is attached to the circumferential surface of a conductive material cylinder la, which serves as a photoreceptor layer support, and the length dimension of the transfer roller 12, which is a rotating body for transfer, that is, the transfer portion width! This shows a related structure formed by coating with a width H1 larger than that shown in FIG. The apparatus of this example is of a reversal development type in which the image-exposed portion of the photoreceptor 1 is subjected to development processing.

The width of the primary charging by the charging means 2 is made wider than the transfer roller width I and narrower than the width H8 of the photoreceptor layer 1b. Also, as a matter of course, image formation (exposure/development) is performed using the width W of the transfer material 12.
1. Do it in a narrower range. Further, the effective development width of the developing device 4 is made narrower than the primary charging width.

With the above configuration, the developer does not adhere to the surface of the photoreceptor 1 within the width I of the transfer roller.

The following two major advantages of this configuration are:
There is a point.

(1) Since the coating width H1 of the photoreceptor layer 1b is wider than the transfer roller width I, if primary charging is performed in a range wider than the transfer roller width (■), the developer will not adhere to the photoreceptor layer 1b, and the transfer roller 12
is not contaminated. Furthermore, since the cleaning device 6 can perform cleaning over a wider range than the transfer roller width I, staining of the transfer roller 12 can be suppressed.

(2) By applying a reverse bias as shown in FIG. 2 when the photoreceptor 1 and the transfer roller 12 are rotating (between sheets, forward rotation, and rear rotation) when the transfer material is not passing through. The developer that has adhered to and contaminated the transfer roller 12 can be retransferred and adhered to the first surface of the photoreceptor, thereby cleaning the transfer roller 12.

That is, by switching the bias power supply for the transfer roller 12 to the reverse bias (negative voltage) power supply 19, the developer tc adhering to the surface of the transfer roller 12 is reduced to the ground 14.
The transferred image is re-transferred onto the circumferential surface of the photoreceptor 1 and transferred to the transfer roller 12.
removed (cleaned) from the surface. The retransferred developer 1d on the surface of the photoreceptor 1 is removed from the surface of the photoreceptor by the cleaning device 6.

Although this embodiment has been described with respect to a reversal development type apparatus, it is equally effective in a regular development type apparatus in which a non-image area is exposed.

Experimental example Regarding the image forming apparatus with the above configuration (Fig. 7 and Fig. 1),
As the photoreceptor 1, an aluminum cylinder (photoreceptor layer support material) la having an outer diameter of approximately 30 mm is coated with an organic semiconductor (non-dielectric constant 3.0, photoreceptor layer) lb in a width of H, = 230 mm. , the organic semiconductor ib is rotated at a circumferential speed of 100 ff1 m/sec (process speed), and the peripheral surface of the organic semiconductor ib is charged to -700 V by a primary charger 2, and the charged surface is scanned and exposed to a laser beam 3 to expose the beam irradiation area. The organic semiconductor lb surface was optically attenuated to -100 V to form an electrostatic latent image of a target image.

This is charged to about -5μc/gr and has a particle size of about 10μ.
A one-component developer of m was applied by the developing device 4 to visualize the image. In the developing device 4, a DC bias voltage of -500 V and an AC bias voltage of a vehicle peak value of 1600 V and a rectangular wave of 1800 H2 were applied in a superimposed manner to a non-magnetic metal sleeve to cause the developer to adhere to the electrostatic latent image. The thus developed image 1j was transferred tb onto a transfer material 11 using the transfer roller 12 shown in FIG. At this time, the transfer roller 12 used was one in which a conductive elastic body with a wall thickness of 5 mm was adhered over a length I=220 mm on a stainless steel core metal with an axial length of 250 nm and an outer diameter of 6 mm. This conductive material has a specific resistance of 105 to 106 Ω・cm・
A material with an Asker-C hardness of about 30 degrees is acceptable, and specifically "Rubicel" (registered trademark) manufactured by Toyo Polymer Co., Ltd. is preferred.

When performing image transfer with the above configuration, the transfer current shows different values depending on the image to be formed, and in the case of a solid black image, it is 0.
In the case of a solid self-portrait, it was 2.0 μA. In a character pattern in which the ratio of dots to the area of the transfer material 11 is 4%, a transfer current of 1.5 μA flows. The edges remained clean and the image remained in good condition.

Embodiment 2 (FIG. 3) FIG. 3 shows the photoreceptor 1 in the image forming apparatus shown in FIG.
, the photoreceptor layer 1b is provided with a required width H2, and the photoreceptor is placed on the circumferential surface portion h-h of the conductive cylinder (photoreceptor layer support material) la on the outer side from both sides in the width direction of the photoreceptor layer 1b. An extension material layer IC 1c made of a material different from that of the photoreceptor layer 1b is formed in series with the layer 1b to have approximately the same thickness as the width H2 of the photoreceptor layer 1b and the overall width J+H2+J of the width J-J of the extension material layer 1cm1c. A related configuration is shown in which the transfer portion width l is larger than the transfer portion width l.

The extended material layer IC/IC is insulating (high resistance) in this example.
This is a resin coating layer. Hereinafter, this will be referred to as an insulating layer.

Here, the latent image development conditions are required to be such that no development occurs in the insulating layer portion IC. For example, when the -order charging width is smaller than J+) (2+J, or when the -order charging width is the same as the width H2 of the photoreceptor layer 1b (that is, when the insulating layer is not charged), the width of the developing area is H2.
The following may be considered.

What is important is the width H of the photoreceptor layer 1b on the photoreceptor layer support material la.
2 and the width J-J of the insulating layer IC.

This configuration has the following three major advantages.

(1) In this way, the charging width is larger than the width of the transfer roller, making it difficult to cause stains due to developer scattering, and cleaning can be performed over a wider range than the width of the transfer roller 12. Contamination at the end of the transfer roller can be suppressed to the same extent as the photoreceptor layer width H2.

(2) At the same time, it is possible to insulate the photoreceptor layer supporting material 1a of the photoreceptor 1 and the transfer roller 12, so it is possible to prevent a reduction in transfer voltage due to leakage and a transfer failure due to a reduction in transfer current at the transfer section. .

(3) The above (+) and (2) have the same effect as the above-mentioned Example 1, but the width H2 of the photoreceptor layer 1b becomes smaller by using the structure of this example, so it is not expensive. The amount of photoreceptor layer material used can be saved, and costs can be reduced.

Furthermore, in the area where image formation is not performed, a layer of 1 cm is added.
Since the range of material selection for 1c is expanded, materials with better chargeability than the photoreceptor layer 1b (for example, polyethylene terephthalate film formed), materials with good slipperiness and easy to clean with a cleaning blade, and materials that are difficult to attract dirt. A substance (for example, a thermosetting film in which fine powder of tetrafluoroethylene is dispersed) can be used.

Although this embodiment has been described with respect to reversal development, it is also effective when configuring an image forming apparatus that performs regular development.

Example 3 (Figures 4 to 6) This example is based on the extended material layer IC in Example 2 (Figure 3).
-The IC has two upper and lower layers, 1d and 1e. The lower layer 1e is an insulating material layer, and the upper layer 1d is a conductive material layer. In addition to the insulating resin layer, the lower layer 1e may be an extension layer of the photoreceptor layer 1b. The upper layer 1d may be a conductive resin layer or other metal plating layer.

A power supply brush 2 is provided for the upper conductive material layers 1d and 1d.
The transfer roller 12 is powered by power supplies 13 and 24 via 1 and 21.
A larger bias is applied than the bias for.

Width H2 of photoreceptor layer 1b, width J- of extension material layer IC/IC
The relationship between J and the width of the transfer portion (■) is the same as in the second embodiment.

The cleaning width of one surface of the photoreceptor by the cleaning blade 6b is set to be larger than the transfer portion width (2) and narrower than the sum J+)i, +J of the photoreceptor layer width H2 and the extension material layer width J-J.

By performing primary charging over the entire width H2 of the photoreceptor layer with the above configuration, it is possible to constantly remove stains caused by the developer at the end of the transfer roller. In other words, the width of the primary charge only needs to be H7, and while it had to be wider than the transfer roller width I in the first and second embodiments, the width of the -order charge can be made smaller.

To explain with reference to FIG. 6, the developer tc (negatively charged developer in this example) that has adhered as dirt to the peripheral surface of the end of the transfer roller 12 is removed from the peripheral surface of the end of the transfer roller 12. The transfer roller 12 is always connected to the conductive material layer IC, which is the upper layer of the extension material layer 1c on the side of the photoreceptor 1, by the power supply 24.
Since a larger bias is applied, the negatively charged adhering contaminated developer tc is transferred 1.1 onto the surface of the conductive material layer 1d, and the transferred developer 1.1 is cleaned by the cleaning blade 6b and cleaned. It is collected in the device 6.

This configuration has the following new effects in addition to the advantages of the first and second embodiments described above.

(1) The end portion of the transfer roller 12 can be constantly cleaned.

(2) Since the charging width can be made small, the primary charger can be made smaller, and the device can be made more compact.

Although this embodiment has been described with respect to an inversion phenomenon, the same effect can be obtained in a normal phenomenon.

Further, in each of the above embodiments, the transfer roller serving as the transfer rotating body may be a transfer belt.

(Effects of the Invention) As described above, according to the present invention, in an image forming apparatus using a transfer rotor as a transfer means, contamination due to developer adhesion on the transfer rotor is prevented, and good image formation is always possible. It can output stably. Furthermore, it is possible to improve the cleaning performance of the image carrier surface by means of cleaning means, and to reduce the width of the -order charge, thereby making it possible to design a more compact device.

[Brief explanation of the drawing]

'rjS1 Figure is a vertical cross-sectional view of the main part of an embodiment in which the width of the photoreceptor layer is set larger than the width of the transfer part, Figure 2 is an explanatory diagram of refreening of the transfer roller, and Figure 3 is a view in the width direction of the photoreceptor layer. Vertical cross-sectional view of the main part of the embodiment in which extension material layers are provided on both sides, No. 4
The figure shows an example of a photoreceptor with an upper and lower extension material layer.
A perspective view of the transfer roller/cleaning plate, FIG. 5 is a vertical cross-sectional view of the photoreceptor, FIG. 6 is a diagram explaining the principle of removing developer attached to the end of the transfer roller, and FIG. 7 is a diagram showing the use of the transfer roller as a transfer means. A schematic diagram of the configuration of an example of an image forming apparatus (LBP),
Fig. 8 is a vertical cross-sectional view of the photoreceptor, Fig. 9 is a diagram explaining the principle of transfer,
FIG. 10 is a diagram showing the relationship between the width of the photoreceptor layer, the transfer area width, and the cleaning width. FIG. 11 is a diagram explaining leakage of transfer current. FIG. 12 is an example of an image forming apparatus using a charger as a transfer means (
This is a schematic diagram of the configuration of LBP. 1 is a drum-type photoreceptor as an image carrier, 1b is a photoreceptor layer, 1a is its support material (cylindrical body made of conductive material), 1c is an extension material layer portion, 12 is a transfer roller as a rotating body for transfer, H −
H, ・H2 is the photoreceptor layer width, ■ is the transfer part width, W sa
X is the transfer material width, J is the extension material layer width, and K is the cleaning width. Patent applicant: Canon Co., Ltd. Representative
Figure 3

Claims (2)

[Claims] (1) A method in which a target image is formed on the image forming layer surface by relatively moving an image carrier having an image forming layer on the support material surface and an image forming means, and the formed image is transferred onto the transfer material surface. The image forming means includes an electrostatic latent image forming process means including a charging means for uniformly applying a charge to the surface of the image forming layer of the image carrier, and a developing means for making the latent image visible with a developer. In an image forming apparatus having a transfer rotary body that transfers the developed image onto a transfer material surface, the image forming layer provided on the support surface of the image carrier in a direction perpendicular to the relative movement direction of the image carrier and the image forming means. The image forming layer width dimension is set to be larger than the width of the transfer portion in the direction perpendicular to the relative movement direction between the image carrier and the transfer rotor with respect to the transfer portion of the image carrier surface by the transfer rotor. Image forming device. (2) A method in which a target image is formed on the image forming layer surface by relatively moving an image carrier having an image forming layer on the support material surface and an image forming means, and the formed image is transferred onto the transfer material surface. The image forming means includes an electrostatic latent image forming process means including a charging means for uniformly applying a charge to the surface of the image forming layer of the image carrier, and a developing means for making the latent image visible with a developer. In an image forming apparatus having a transfer rotary body that transfers the developed image onto a transfer material surface, an image forming layer is provided on a support material surface of an image carrier in a direction perpendicular to the relative movement direction of the image carrier and image forming means. The width dimension is set to a predetermined value, and an extended material layer portion made of a material different from that of the image forming layer is provided in series with the image forming layer and having approximately the same thickness on the supporting material surface portion outside of both sides in the width direction of the image forming layer. , the entire width dimension of the image forming layer and the extension material layer portions on both sides thereof is in a direction perpendicular to the direction of relative movement between the image carrier and the transfer rotor with respect to the transfer portion of the image carrier surface by the transfer rotor. An image forming apparatus characterized in that the image forming apparatus is larger than the part width.