JPH0643729A - Image forming device forming multi-image with multicolor toner on transfer material - Google Patents

Abstract

PURPOSE:To prevent the rear soiling of a transfer material, to increase efficiency in an image forming process, moreover, to improve the quality of an image formed on a transfer material, and to increase image forming efficiency, when a multi-image is formed by plural photosensitive drums. CONSTITUTION:The photosensitive drums 1a, 1b, 1c, and 1d are rotated and a toner image for measuring a density (subsequently, it is called 'a reference toner image'), on the image forming regions of these photosensitive drums 1a,..., and 1d. The density of the reference toner image is measured by density measuring sensors 23a, 23b, 23c, and 23d, and a control means 24 adjusts the density based on the result of the measurement. The reference toner image whose density is completed to measure is transferred on a carrying belt 8, but a region where the reference toner image is transferred, is a region (nonimage region) where a transfer material is not placed, so that the rear of the transfer material is not soiled. The transfer material is placed with the nonimage region avoided, to continue image formation without stopping.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming a multiple image with a plurality of color toners on a transfer material, and is particularly suitable for use in a color copying apparatus having a plurality of electrophotographic photoconductors. More specifically, it relates to image density control.

[0002]

2. Description of the Related Art Conventionally, various image forming apparatuses, more specifically, various color copying apparatuses for forming a multiple image by a plurality of color toners on a transfer material have been proposed. FIG. 4 shows a typical example thereof.

FIG. 4 is a vertical sectional view of a color copying machine. Inside the copying apparatus main body C, there are four image forming units P.
a, Pb, Pc, and Pd are arranged at substantially the same height, and these image forming portions Pa, ..., Pd are photosensitive drums (electrophotographic photosensitive members) having an endless electrophotographic photosensitive layer formed on the surface thereof. ) 1a, 1b, 1c, 1d. The photosensitive drums 1a, ..., 1d arranged in parallel are rotatably mounted, and the apparatus main body C is arranged so that their rotation axes are parallel to each other.
And is configured to rotate in the direction of the arrow by drive means (not shown).

.., 1d above the photosensitive drums 1a ,.
An exposure device (light information irradiation means) L for irradiating d is disposed so as to face the photosensitive drums 1a, ..., 1d, and light from a light source device (not shown) is rotated by the polygon mirror 17 to rotate the photosensitive drum. 1d is irradiated onto the drums 1a, ..., 1d to form electrostatic latent images on the drums 1a ,.

Further, these photosensitive drums 1a, ..., 1d
, 1d primary charging devices 2a, 2b, 2c, 2d for charging the surface of the photosensitive drums 1a, ..., 1d to a uniform potential,
, 1d, and potential sensors 22a, 22b, 22c, 22d for measuring the surface potentials of the photosensitive drums 1a, ..., 1d, and toners of respective colors (yellow, magenta, cyan, and black) are housed on the photosensitive drums 1a ,. Developing devices (developing means) 3a, 3b, 3c, 3d for converting the electrostatic latent image (electrostatic latent image formed in the irradiation region by the exposure device L) into a toner image of each color
, Transfer charging devices (transfer means) 4a, 4b, 4c, 4d for electrostatically transferring each color toner image developed by these developing devices 3a, ..., 3d onto a transfer material S (described later), and a photosensitive drum. , 1d, and cleaning devices 5a, 5b, 5c, 5d for removing the residual toner on the photosensitive drums 1a, ...
a, 21b, 21c and 21d are arranged in order. Then, these photosensitive drums 1a, ..., 1d
Are arranged at equal intervals along the conveyance direction of the transfer material S, and toner images of four colors of yellow, magenta, cyan, and black are sequentially arranged from the front side (right side in FIG. 4) of the apparatus main body C. Configured to form. It should be noted that the transfer charging devices 4a, ...
a, 41b, 41c, 41d, and the transfer pressing members 41a, ..., 41d press the conveyor belt 8 (described below).

On the other hand, these photosensitive drums 1a, ..., 1d
A transfer belt (transfer material transfer unit) 8 is disposed below the upper side, and the transfer belt 8 is wound between rollers 10 and 11 to be rotationally driven (endlessly moved). The transfer belt 8 is connected to the transfer charging device 4a, ...
, 4d are in contact with the facing portions of the photosensitive drums 1a, ..., 1d (hereinafter, referred to as “transfer positions”), and a plurality of transfer materials are simultaneously supported and conveyed to the transfer positions. The conveyor belt 8 is formed of a dielectric resin film such as a polyethylene terephthalate resin film sheet (PET sheet), a polyvinylidene fluoride resin film sheet, or a polyurethane resin film sheet, and both ends thereof are superposed on each other. The endless shape, such as a seamless belt having no joint, is used. In the case of a belt having a joint, a means for detecting the position of the joint may be provided so that the toner image is not transferred on the joint.

Further, a belt charge eliminator 12 and a belt cleaning means (transfer material conveying means cleaning means) 16 are provided at a position facing the conveying belt 8, and the photosensitive drum 1a of the conveying belt 8 is disposed. , ..., 1
The toner remaining on the side opposite to d is removed by the belt static eliminator 12
After removing the static electricity by the electrostatic attraction force, the belt cleaning means 16 removes the electrostatic attraction force. The belt cleaning means 16 is configured such that the rotating fur brush faces the side where the photosensitive drum is located.
Alternatively, a non-woven fabric may be used, or they may be used in combination. Reference numeral 16a denotes an elastic member such as a brush for pressing the belt 8 against the brush 16.

On the other hand, on the front side of the apparatus main body C, a cassette 60 containing a large number of transfer materials S on a cut sheet is provided outside the apparatus main body C so as to be transferred to the upper rear side of the cassette 60. A pickup roller 26 that sequentially discharges the material S from the cassette 60 is provided. A pair of registration rollers 13 is disposed near the pickup roller 26. The registration rollers 13 are rotatably supported by the apparatus main body C and are rotatably driven by a driving means (not shown). . The cassette 60, the pickup roller 26, and the registration roller 13 constitute a transfer material supply unit, and supply the transfer material S to the conveyor belt 8.

Further, a fixing device 7 is provided on the inner side of the apparatus main body C, and the fixing device 7 includes the fixing roller 7
1, pressure roller 72, heat-resistant cleaning members 73 and 74 for cleaning each of them, and rollers 71 and 7 of each
The heaters 75 and 76 for heating the two, the oil application roller 77 for applying the release agent oil such as dimethyl silicone to the fixing roller 71, and the oil sump 7 for supplying the oil.
8. The thermistor 79 for fixing temperature control is provided,
The toner image on the transfer material S transported by the transport belt 8 is fixed.

Upon receipt of a predetermined image forming signal, the photosensitive drums 1a, ..., 1d are rotatably driven by driving means (not shown), and the primary charging devices 2a ,.
2d starts to uniformly charge the photosensitive drums 1a, ..., 1d. Further, the exposure device L includes the photosensitive drums 1a, ..., 1d.
The developing devices 5a, ..., 5d are exposed to yellow, magenta, and
The cyan and black color toners are used for the photosensitive drum 1.
A toner image of each color is formed by adhering to the electrostatic latent image portion on a, ..., 1d.

On the other hand, since the pickup roller 26 is rotationally driven by receiving a predetermined signal, the cassette 60 is previously set.
The transfer material S stored in is fed into the apparatus main body C and placed on the conveyor belt 8. This conveyor belt 8
Are rotatably driven by a driving means (not shown), and the transfer material S is held by the electrostatic attraction force to the respective photosensitive drums 1a,
... is conveyed to the back side of the apparatus main body C while being in contact with 1d. Then, the transfer material S is transferred to each of the photosensitive drums 1a, ..., 1d.
, 6d, a high voltage is applied to the transfer charging devices 6a, ..., 6d so that the toner images of the respective colors on the photosensitive drums 1a ,. On the basis of the above, a multiple image of a plurality of color toners is formed on the transfer material S. After that, the transfer material S is conveyed to the fixing device 7, the toner image on the transfer material S is fixed by the fixing device 7, and then the transfer material S is discharged to the outside of the apparatus main body C. On the other hand, each photosensitive drum 1a, ..., 1d
The toner remaining on the top is cleaned by the cleaning device 7a, ...,
, 7d, and the photosensitive drums 1a, ..., 1d are ready for image formation again.

By the way, in the copying apparatus having the above structure, image density control is performed in order to make the density of the toner image optimum for the original image. next,
The image density control will be described.

, 1d are provided with density measuring sensors (measuring means for developing images for detection) 23a, 23b, 23c, 23d, and the copying machine main body C. The control unit 24 (image forming condition adjusting unit) for optimizing the image forming condition is built in. Then, when controlling the density of the toner image formed on the photosensitive drum, a reference latent image for density measurement is formed on the photosensitive drums 1a, ..., 1d by irradiation of optical information based on a predetermined signal. , 23d, the density measuring sensors 23a, ..., 23d are toner images for detection (reference latent image for density measurement) formed in the image forming area of the photoconductor by the developing devices 3a ,. Is visualized, and hereinafter referred to as “reference toner image”)
The image forming state of the photoconductor is measured. Further, the control means 24 is adapted to adjust the image forming condition on the photoconductor based on the measurement result.

There are various control methods by the control means, but as typical ones, (1) the charging bias applied to the primary charging devices 2a, ... , Or a method of changing the so-called development contrast by controlling the development bias applied to the developing devices 3a, ..., 3d, (2) In the digital copying apparatus, the density gradation is applied to the input video signal. In order to guarantee, a method of changing or correcting the look-up table, (3) In the two-component developing system, the developing device 3a, ..., With an amount of toner corresponding to the amount consumed by copying.
There is a method of supplying 3d. Among these control methods, (1) and (2) are known as methods for keeping the image reproducibility more stable.

[0015]

In the copying apparatus described above, even when a large number of transfer materials S are continuously fed to form an image, the above (1), (2), or (3) is used. It was necessary to frequently perform the image density control in (2) to properly manage the density of the toner image. Further, in the two-component developing method of (3), the toner is charged by frictional charging with the carrier, but if a large amount of toner is replenished at once, it takes time to uniformly disperse the toner and the carrier.
The triboelectrification may not be performed uniformly, so that an appropriate image may not be formed. In order to prevent this, it is necessary to frequently control the image density. When the image density control is frequently performed in this way, it is necessary to form the reference toner image on the photosensitive drums 1a, ..., 1d accordingly. On the other hand, in the digital copying apparatus, the digital data corresponding to the density of the original image is used as the drive signal of the exposure apparatus L after being subjected to a predetermined conversion, but the digital data is consumed based on the totalization of the digital data. The calculated toner amount is calculated, and the image density control is performed based on the calculated result. In such a case, it is not necessary to form the reference toner image so frequently, but in order to correct the error that occurs when the digital data is aggregated, a predetermined interval (usually 1 for every 100 times of copying is performed). It is necessary to form the reference toner image in each time.

The reference toner image thus formed comes into contact with the conveyor belt 8 as the photosensitive drums 1a, ..., 1d rotate, and the electrical action of the transfer charging devices 4a ,. The transfer belt 8 is transferred onto the conveyor belt 8 due to the pressing force of 41a, but the more frequently the reference toner image is formed, the more severe the conveyor belt 8 becomes. The belt cleaning means 16 as described above is provided to remove such dirt, but depending on the material of the conveyor belt 8 (for example, polycarbonate), it may be 1
Some cleanings do not remove enough.
When the transfer material S is placed on the soiled portion, the back surface of the transfer material S is soiled, which is not preferable. On the other hand, there is a method in which the conveyor belt 8 is rotated a plurality of times without forming an image to completely clean the conveyor belt 8 and then the transfer material S is supplied to restart the image formation. However, when the image forming is not performed during the cleaning as described above and the entire conveyance belt 8 is waited for sufficient cleaning, it takes a long time to finish the cleaning because the movement amount of the conveyance belt 8 is large.
Therefore, it takes time until the image formation is restarted and the restarted image formation is completed, and the efficiency is inevitably lowered.

Therefore, the present invention solves the above-mentioned conventional problems, improves the efficiency of the image forming process when forming a multiple image by a plurality of electrophotographic photoconductors, and improves the image quality formed on the transfer material. Enables improvement of image forming efficiency and image forming efficiency,
Another object of the present invention is to provide an image forming apparatus that prevents the transfer material from being soiled on the back side.

[0018]

The present invention has been made in view of the above circumstances, and the first invention is an endless image forming apparatus for forming a multiple image with a plurality of color toners on a transfer material. Electrophotographic photoconductors each having a circular electrophotographic photoconductive layer, means for irradiating light information, which are arranged so as to face each photoconductor, and development for developing an area irradiated by the light information irradiating means with color toners. Means, a transfer means for electrostatically transferring the toner image developed by the developing means onto a transfer material, and a photosensitive member provided by each developing means for detecting the image forming state of the photosensitive body. Based on the measurement result of the detection developing image measuring means for measuring the state of the detection toner image formed in the image forming area within the width in the direction orthogonal to the moving direction, and the measurement result by the detection developing image measuring means. Image formation on the photoconductor The adjustment means for adjusting the image forming conditions and the transfer means of each photoconductor contact the photoconductor, and move endlessly to convey the transfer material to the transfer position of each photoconductor. And a transfer material transporting unit that has a length that is an integral multiple of the sum of the length of the image area formed by one photoconductor and the non-image area that occurs between the image areas, and that supports and transfers a plurality of transfer materials at the same time. A transfer material supply means capable of sequentially supplying the transfer material to the transfer material transfer means, and a transfer material transfer means cleaning means which is disposed so as to face the transfer material transfer means and cleans a surface of the photosensitive member side. And a toner image for measuring by the developing image measuring means for detecting the image forming state, which is in the image forming area of the photoconductor, and is not in the transfer material conveying means. It is formed on the photoconductor corresponding to the image area. That.

In this case, in order to form the toner image to be measured by the developing image measuring means at the position corresponding to the non-image area of the transfer material conveying means, the timing of image formation on the photoconductor is changed. It may be done by doing so.

Further, in order to form the toner image to be measured by the developing image measuring means at a position corresponding to the non-image area of the transfer material conveying means, the transfer material supply timing to the transfer material conveying means is set. It may be performed by changing it.

Further, a toner image to be measured by the developing image measuring means is formed in the image forming area of the photoconductor and at a portion corresponding to a specific image area of the transfer material conveying means, and this toner image is formed. By not supplying the transfer material to the position corresponding to the transfer material conveying means, the transfer material conveying means may be set as the non-image area.

Further, in order to detect the image forming state of the photoconductor, the detecting toner image formed by the developing means is formed in the middle of the continuous image forming process of a plurality of sheets. May be.

On the other hand, a second invention is an image forming apparatus for forming a multiple image by a plurality of color toners on a transfer material,
A plurality of electrophotographic photosensitive members having an endless electrophotographic photosensitive layer, means for irradiating light information, which are arranged so as to face each photosensitive member, and an area irradiated by the light information irradiating means is developed with color toner. A developing unit, a transfer unit that electrostatically transfers the toner image developed by the developing unit onto a transfer material, and a photosensitive member that is provided on each photoconductor to detect the image forming state of the photoconductor. Image forming conditions on the photoconductor, based on the measurement result of the detection developing image for measuring the state of the detection toner image formed in the image forming area and the measurement result of the detection developing image. Adjusting means for adjusting image forming conditions and the transfer means of each photoconductor contact this photoconductor, and move endlessly to convey the transfer material to the transfer position of each photoconductor. Image area and each image by one photoconductor A transfer material conveying unit that has a length that is an integral multiple of the sum of the non-image areas that occur between the regions and that supports and conveys a plurality of transfer materials at the same time, and the transfer material is sequentially transferred to the transfer material conveying unit. A transfer material supplying means capable of supplying the transfer material, a transfer material conveying means cleaning means arranged to face the transfer material conveying means and cleaning the surface of the photoconductor side, and a cleaning state by the cleaning means. A cleaning result detecting unit, a toner image for detecting the image forming state is formed in an image forming area of the photoconductor, and the cleaning is performed by the cleaning result detecting unit of the transfer material conveying unit. The transfer material is supplied to the area in which the above is confirmed.

In this case, the toner image for detection is formed in an area smaller than the minimum size of the transfer material to be applied, and the cleaning means acts only on the toner image formation area for detecting the image forming state. Yes, you may.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. The same parts as those of the prior art shown in FIG.

FIG. 1 shows a structure of a main part of a copying apparatus to which the present invention is applied. As a material of the conveyor belt (transfer material conveying means) 8, rubber, resin, or the like, or polycarbonate is used. Good. The conveyor belt 8 has an “image area” on which the transfer material S is placed and a document image is formed, and a “non-image area” between the image areas where the transfer material S is not placed. The circumference of the conveyor belt 8 is an integer multiple of the sum of the length of the image area and the length of the non-image area formed by the interval between the transfer materials (hereinafter, these "images"). "Area" and "non-image area" refer to areas on the conveyor belt 8 and are distinguished from areas on the photosensitive drums 1a, ..., 1d (image forming areas)). The length of the image area is
For example, it is equal to the width of the transfer material S of A4 size in the lateral direction. Then, the reference toner image for density measurement is
, 1d are formed in the image forming areas of the photosensitive drums (electrophotographic photoreceptors) 1a, 1d, and the formed reference toner image is transferred to the non-image area of the conveying belt 8.

Since the belt cleaning means (transfer material conveying means cleaning means) 16 generally tends to sweep the toner on the conveyor belt 8 in the downstream direction, the place where the transfer material S is not placed is as described above. It is a portion of the transfer material S space where the transfer material S is not placed (formed at a specific space in a specific portion in the area from Y ₁ to Y _{10 in the} drawing).

Regarding the cleaning of the conveyor belt 8,
It is preliminarily measured how many times the cleaning should be performed until the rear surface of the transfer material S is soiled, and the cleaning operation is canceled after the conveyance belt 8 has passed the cleaning this number of times.

In the above embodiment, the reference toner image is the size of the minimum transfer material (size in the width or length direction).
The size is smaller than the above, and is set within the interval between the transfer materials (that is, the non-image area). The length of the transfer material transport belt is an integral multiple of the sum of the image area and the non-image area (described above), but the definition of the image area is determined by the minimum size of the transfer material to be applied.

By the way, as described above, the reference toner image is transferred onto the non-image area of the conveyor belt 8. As a specific method therefor, the photosensitive drum 1
There is a method of changing the timing of image formation on a, ..., 1d to shift the formation start position of the reference toner image on the photosensitive drums 1a, ..., 1d to the front or rear of the normal image formation position. This makes it possible to form the reference toner image in the non-image area.

Further, as a specific method of forming the reference toner image in the non-image area, the conveying belt 8 is not distinguished in advance between the image area and the non-image area as described above, but the photosensitive drums 1a, The reference toner image is formed at a predetermined timing in the image forming area on 1d, and the reference toner image is formed at a predetermined position of the conveyor belt 8, but the toner image is formed by shifting the supply timing of the transfer material S. There is a method in which the transfer material is placed in a non-existing place. As a result, the image forming area of the photosensitive drum can be a non-image area when viewed from the placement position of the transfer material. For example, when the reference toner image is formed at a predetermined timing, the reference toner image is transferred to a specific position on the conveyor belt 8. Then, the supply timing of the transfer material S is appropriately controlled so that the transfer material S is not placed at the position where the reference toner image is transferred, and the back stain of the transfer material S can be prevented.

As described above, the plurality of photosensitive drums 1a,
.., 1d are arranged side by side, the length of the conveyor belt 8 required to form one completed image is long, so that the cleaning process for the conveyor belt 8 does not have to wait. Since the supply of the transfer material can be started, the effect is great in improving the image forming efficiency.

Next, as a modification (embodiment) of the example of forming the reference toner image on the non-image area of the conveyor belt 8, the reference toner image is formed in a predetermined image forming area of the photosensitive drums 1a, ..., 1d. Then, the reference toner image is formed on the area of the transport belt 8 on which the transfer material is originally placed (limited to the area of one or several sheets of the transfer material), but to the portion where the reference toner image is formed. The transfer material S may be placed (supplied) after waiting for the number of times of cleaning by the cleaning means 16 in this area of the transport belt 8 to be completed.

That is, the number of times of completion of cleaning is set in advance, and the portion of the belt that is soiled with the reference toner image waits for the set number of times to pass through the cleaning means.
During that time, the supply of the transfer material S to the conveyor belt 8 (the portion on which the reference toner image is formed) is stopped, and after the cleaning is completed, the transfer material S to the conveyor belt 8 (the portion on which the reference toner image is formed). Start supply.

Since the removal of the stain by the reference toner image on the belt 8 has been completed by the end of the number of cleanings, there is no risk of stain on the back side even when the transfer material S is placed. Further, in the portion where the reference toner image is not formed, even if the transfer material S is placed before the cleaning is completed, there is no risk of back stain. Therefore, by supplying the transfer material S to such a portion (the portion where the reference toner image is not formed) and continuing the image formation, the efficiency of the image output can be improved.

In this embodiment, the area where the transfer material is placed and the portion of the belt 8 which is soiled by the reference toner image is not transferred until the predetermined cleaning process is completed. The dirty area is conveyed by the conveyor belt 8.
Is defined as the non-image area of.

Next, another embodiment of the present invention will be described with reference to FIG.

Surface sensor shown in the figure (cleaning result detecting means)
R is for detecting dirt such as toner adhering to the surface of the conveyor belt 8 (in other words, a cleaning state by the cleaning unit 16), and particularly at a position facing the conveyor belt 8 after a detection signal is generated. The transfer material S is provided at a position where the transfer material S is placed on the conveyor belt 8 without any time loss (a position separated from the placement position of the transfer material S by a distance Ls). A control means 25 is connected to the surface sensor R, and the control means 25 determines whether or not the transfer material S can be placed on the conveyor belt 8 based on a signal from the surface sensor R (that is, cleaning by the cleaning means 16). It has been designed to judge whether or not). Then, the control means 25 causes the transfer material S to be moved to any position in the conveyor belt 8.
When it is determined that the transfer material S can be placed, the motor 27 of the pickup roller (transfer material supply means) 26 is activated to feed the transfer material S stored in the cassette 60 into the copying apparatus main body C. There is. Further, the transferred transfer material S is transferred to the photosensitive drums 1a, ...
It is further transported after being synchronized with the rotation of 1d.

The position at which the surface sensor R is arranged can be obtained by the following equation.

Ls = Vp × (L1 / Vf + a) where Ls is the distance from the position where the surface sensor R is arranged to the position where the transfer material S is placed on the conveyor belt 8 (see FIG. 2). Further, Vp is the process speed, L1 is the distance from the position of the pickup roller 26 mounted above the cassette 60 to the position where the transfer material S is placed on the transport belt 8, and Vf is Cassette 6
A is the average speed of the transfer material S fed from 0, a is the transfer material S
The time required to release the control mode for prohibiting the placement and to give the placement instruction is shown.

In the above embodiment, for example, it is determined that the transfer material S cannot be placed because the reference toner image is formed only on Y ₂ and Y ₄ between Y ₁ and Y ₁₀ of the conveyor belt 8 in FIG. When this occurs, the transfer material S is supplied to another area, so that the efficiency of image output can be improved. The fact that the reference toner image is formed only on Y ₂ and Y ₄ means that the exposure device L
The signal from the sensor R can be used to determine whether or not the cleaning of the reference toner images formed on these Y ₂ and Y ₄ is completed.

Further, another embodiment of the present invention will be described with reference to FIG.

When a resin film such as polycarbonate is used as the material of the conveyor belt 8 used in the embodiment of the present invention, as described above, the belt cleaning means 16 is used.
It may happen that the toner on the conveyor belt 8 cannot be sufficiently removed by operating the transfer material S only once, and if the transfer material S is placed on the portion where the toner is not removed and remains.
It is not good for the back side to become dirty.

In cleaning, the toner on the conveyor belt 8 generally tends to be swept in the downstream direction. Therefore, the reference toner image is formed as close to the front end side (upstream side) of the transfer material as possible, and is cleaned in the downstream direction by the cleaning means 16. Prevent the swept toner from adhering to other adjacent image areas. When the reference toner image is not formed on the front end side of the transfer material and another image area adjacent to the area where the reference toner image is formed is soiled by the above-mentioned toner sweeping, the reference toner image is formed. The formed area and the area that becomes dirty due to the sweeping of the toner are non-image areas on which the transfer material S is not placed, and the transfer material S is not placed on these areas until the toner is removed. It should be noted that whether or not the toner has been removed may be determined by whether or not cleaning has been performed a predetermined number of times, as in the above-described embodiment, or may be determined by the surface sensor R.

By the way, in the present embodiment, the belt cleaning means 16 operates only on the contaminated portion of the conveyor belt 8 to which the toner adheres. As a result, the toner adhering to the conveyor belt 8 is removed and the belt cleaning means 16 operates only when necessary, so that the abrasion thereof is minimized.

The range in which the belt cleaning means 16 operates is preferably from the leading end of the portion corresponding to the transfer material interval to the subsequent end portion of the width of the transfer material in the length direction. Further, by providing the above-described surface sensor R and the like, the placement of the transfer material S is started only in the area where it is confirmed that the transport belt 8 has been cleaned, as in the above-described embodiment. .

As described above, according to the first embodiment, the conveyor belt is divided into the image area and the non-image area in advance, and the reference toner image is not attached to the image area. Even if the image stain is present in the non-image area on the belt, the transfer material is placed in the image area, so that the toner image does not adhere to the back surface of the placed transfer material.

Further, according to the second embodiment, the dirty area of the conveyor belt is cleaned a predetermined number of times, and the transfer material is placed after it is considered that the surface has been cleaned. Therefore, the cleaning process is completed. After that, the toner image does not adhere to the back surface of the placed transfer material. In addition, even when the cleaning of the entire conveyor belt is not completed,
Since the image formation can be continued using the cleaned area, time loss can be reduced and efficiency is not reduced. Further, the same effect can be obtained by detecting with a sensor whether or not the cleaning of the toner image is completed.

Further, according to the third embodiment, the belt cleaning means for cleaning the conveyor belt operates only on the portion where the toner adheres, and the transfer material can be supplied to the other areas. It is possible to prevent toner stains and improve the efficiency of image formation.

The present invention is particularly effective when a plurality of images are continuously formed. In addition, the first embodiment has an effect that the reference toner image can be formed even between consecutive image outputs.

[0051]

As described above, according to the first invention, the transfer material conveying means is divided into the image area and the non-image area, and the toner image for measuring the image forming state is the non-image area. It is formed on the photoconductor corresponding to the area. Therefore,
The toner image is not formed in the image area of the transfer material conveying means, and even if the transfer material is placed on the image area, the toner image may adhere to the back surface of the placed transfer material. Absent. As described above, as a method of forming the toner image on the non-image area in the transfer material conveying means, there are a method of changing the image forming timing on the photoconductor and a method of changing the transfer material supplying timing.

According to the second aspect of the invention, the transfer material is supplied to the transfer material conveying means in the area where cleaning is confirmed by the cleaning result detecting means. The image does not stick. Further, even when the cleaning of the entire transfer material conveying means is not completed, the image formation can be continued using the cleaned area, so that the time loss can be reduced and the efficiency is not reduced.

Further, the transporting means cleaning means for cleaning the transfer material transporting means operates only on the portion where the toner adheres, and the transfer material can be supplied to the other areas, so that the toner is prevented from being contaminated. It is possible to improve the efficiency of image formation.

[Brief description of drawings]

FIG. 1 is a sectional view of essential parts of a copying apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of essential parts of a copying apparatus according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view of essential parts of a copying apparatus according to still another embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view showing a general structure of a copying apparatus.

[Explanation of symbols]

1a, 1b, 1c, 1d Electrophotographic photosensitive member (photosensitive drum) 2a, 2b, 2c, 2d Primary charging device 3a, 3b, 3c, 3d Developing means (developing device) 4a, 4b, 4c, 4d Transfer means (transfer charging) Equipment 5a, 5b, 5c, 5d Cleaning device 7 Fixing device 8 Transfer material conveying means (conveying belt) 10 Roller 11 Roller 12 Belt static eliminator 13 Transfer material supplying means (registry roller) 16 Transfer material conveying means Cleaning means (belt cleaning) 17) Polygon mirrors 21a, 21b, 21c, 21d Static erasing exposure device 22a, 22b, 22c, 22d Potential sensor 23a, 23b, 23c, 23d Measuring means for detecting developed image (sensor for density measurement) 24 Adjustment of image forming conditions Means (Control Means) 25 Control Means 26 Transfer Material Supply Means (Pickup Rollers ) 41a, 41b, 41c, 41d transfer the pressing member 60 the cassette L optical information emitting means (exposure means) Pa, Pb, Pc, Pd image forming unit R cleaning result detection unit (surface sensor) S transfer material Y ₁ to Y ₁₀ Belt Basic unit of circumference

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Claims (7)

[Claims] 1. An image forming apparatus for forming a multiple image of a plurality of color toners on a transfer material, wherein a plurality of electrophotographic photosensitive members having an endless electrophotographic photosensitive layer and a plurality of electrophotographic photosensitive members are disposed so as to face each photosensitive member. Means for irradiating the optical information, developing means for developing the area irradiated by the optical information irradiating means with color toner, and transfer means for electrostatically transferring the toner image developed by the developing means onto a transfer material, The state of the toner image for detection, which is provided on each photoconductor and detects the image forming state of the photoconductor, is formed in the image forming area within the width in the direction orthogonal to the moving direction of the photoconductor by the developing means. And a means for measuring the developed image for detection, and means for adjusting the image forming condition for adjusting the image forming condition on the photoreceptor based on the measurement result by the means for measuring the developed image for detection. At the position of the transfer means In contact with the optical body, it moves endlessly to convey the transfer material to the transfer position of each photoconductor, and when viewed in this moving direction, the sum of the image area by one photoconductor and the non-image area generated between each image area A transfer material conveying means having a length that is an integral multiple of the length and supporting and conveying a plurality of transfer materials at the same time; and a transfer material supplying means capable of sequentially supplying the transfer material to the transfer material conveying means. A transfer material conveying means cleaning means arranged to face the transfer material conveying means and cleaning the surface of the photosensitive material side, and a developed image measuring means for detecting the image forming state. A plurality of toner images to be measured on the transfer material in the image forming area of the photoreceptor and corresponding to the non-image area of the transfer material transporting means. Image forming apparatus for forming a multiple image by the color toners. 2. The timing of image formation on the photoconductor is changed in order to form the toner image to be measured by the developing image measuring means at a position corresponding to the non-image area of the transfer material conveying means. The image forming apparatus according to claim 1, which forms a multiplex image of a plurality of color toners on the transfer material. 3. A transfer material supply timing to the transfer material carrying means for forming a toner image to be measured by the developing image measuring means at a position corresponding to a non-image area of the transfer material carrying means. The image forming apparatus according to claim 1, wherein a plurality of color toners are used to form a multiple image on the transfer material. 4. A toner image to be measured by the developing image measuring means is formed in an image forming area of a photoconductor and in a portion corresponding to a specific image area of a transfer material conveying means, and the toner image is formed. The image for forming a multiple image with a plurality of color toners on the transfer material according to claim 1, wherein the transfer material is not supplied to a position corresponding to the transfer material conveying means, thereby making the transfer material conveying means a non-image area. Forming equipment. 5. The toner image for detection formed by the developing means for detecting the image forming state of the photoconductor is formed in the middle of a continuous image forming process of a plurality of sheets. An image forming apparatus for forming a multiple image by a plurality of color toners on the transfer material as described. 6. An image forming apparatus for forming a multiple image of a plurality of color toners on a transfer material, wherein a plurality of electrophotographic photosensitive members having an endless electrophotographic photosensitive layer and a plurality of electrophotographic photosensitive members are provided so as to face each photosensitive member. Means for irradiating the optical information, developing means for developing the area irradiated by the optical information irradiating means with color toner, and transfer means for electrostatically transferring the toner image developed by the developing means onto a transfer material, A detection developing image measuring unit provided on each photoconductor to measure the state of the detection toner image formed in the image forming area of the photoconductor by the developing unit in order to detect the image forming state of the photoconductor. , Based on the measurement result by the measuring unit of the developed image for detection, the image forming condition adjusting unit for adjusting the image forming condition on the photosensitive member, and the photosensitive member at the position of the transfer unit of each photosensitive member, At the transfer position of each photoconductor It moves endlessly to convey the copying material, and has a length that is an integral multiple of the length of the sum of the image area by one photoconductor and the non-image area that occurs between each image area when viewed in this moving direction, A transfer material conveying means for simultaneously supporting and conveying a plurality of transfer materials, a transfer material supplying means capable of sequentially supplying the transfer material to the transfer material conveying means, and a transfer material conveying means arranged to face the transfer material conveying means. A toner image for detecting the image forming state, and a transfer material conveying means cleaning means for cleaning the surface on the photoconductor side, and a cleaning result detecting means for detecting the cleaning state by the cleaning means. Is formed in the image forming area of the photoconductor, and the transfer material is supplied to an area in which the cleaning is detected by the cleaning result detecting means of the transfer material conveying means. With multiple color toners on material An image forming apparatus that forms multiple images. 7. The toner image for detection is formed in an area smaller than the minimum size of a transfer material to be applied, and the cleaning unit acts only on a toner image formation area for detecting an image forming state. The image forming apparatus according to claim 6, which forms a multiple image with a plurality of color toners on a transfer material.