JPH04218084A - Image forming device - Google Patents

Abstract

PURPOSE:To reduce the labor of a service man required for adjusting transfer nip width. CONSTITUTION:A reference toner image having prescribed width which is sufficiently wider than the transfer nip width is formed on a photosensitive drum 1 (I). The rotation of the drum 1 and an intermediate transfer belt 35 is stopped when the reference toner image arrives at a position where it crosses belt nip width and prescribed transfer bias is impressed on a belt bias roller 51 (II). Thus, the rotation of the drum 1 or the like is started again after the toner image having the width corresponding to the belt nip width is transferred on the belt 53 (III). Then, the toner image on the belt 53 is transferred on a transfer paper and the transfer paper is ejected on a paper ejection tray outside a device (IV). By measuring the width of the toner image on the ejected transfer paper by the service man, the belt nip width is easily recognized.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, or a printer. The present invention relates to an image forming apparatus that transfers images to a transfer material, such as an intermediate transfer member or a final transfer material, under the action of a transfer electric field.

0002

2. Description of the Related Art In this type of image forming apparatus, if the transfer time during which the toner passes through a transfer electric field is insufficient, toner transfer failure occurs. In particular, in those that form a color image by overlapping toner images of each color,
Transfer defects due to insufficient transfer time result in incomplete color reproduction. Therefore, in order to ensure sufficient transfer time, a certain width (hereinafter referred to as
(called nip width). If the nip width changes over time, the nip width has to be adjusted by a service person.

0003

[Problems to be Solved by the Invention] However, this adjustment of the nip width by a service person is performed by trial and error and takes a long time, leading to an increase in maintenance costs. Furthermore, it is necessary to tighten the accuracy of parts forming the transfer area and the assembly accuracy in the device assembly process, leading to an increase in parts costs and assembly costs. The present invention has been devised in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide an image forming apparatus that reduces the effort of a service person in adjusting the nip width.

0004

[Means for solving the problem] The invention according to claim 1 includes:
In an image forming apparatus that transfers a toner image on a toner image carrier to a transfer material under the action of a transfer electric field, a reference toner image having a predetermined width in the moving direction of the toner image carrier is placed on the toner image carrier. means for forming the toner image carrier and the transfer material in a stationary state when the transfer material faces the reference toner image;
means for applying a transfer electric field to a region where the reference toner image and the transfer material face each other; and a means for applying a transfer electric field to an area where the reference toner image faces the transfer material; The apparatus is characterized by being provided with a discharge means for discharging at least one of the transfer material to which the toner image has been transferred, and the other transfer material to which the toner image has been transferred from the transfer material, out of the apparatus. It is something. The invention according to claim 2 provides a width detecting means for detecting the width of the toner image in the transfer material moving direction, instead of or in addition to the ejecting means in the invention according to claim 1, and the width detecting means. The present invention is characterized by further comprising a display means for displaying the detection result by the means. The invention recited in claim 3 is defined as claim 2.
In place of or in addition to the display means in the described invention, an adjustment means is provided for adjusting the width of the area on which the transfer electric field acts based on the detection result by the width detection means. It is. The invention according to claim 4 is:
In place of or in addition to the adjustment means in the invention according to claim 3, a transfer electric field adjustment means is provided for controlling the intensity of the transfer electric field based on the detection result by the width detection means. It is something. The invention according to claim 5, 6, or 7 is characterized in that the width detecting means in the invention according to claim 2, 3, or 4 is configured to detect the width of the toner image bearing member that has passed through a region on which the transfer electric field acts. The present invention is characterized in that the width is detected by detecting the situation.

[0005]

[Operation] The invention according to claim 1 provides the following features:
A reference toner image having a predetermined width is formed in the moving direction of the toner image carrier, and when the transfer material faces the reference toner image, the toner image carrier and the transfer material are brought to a stationary state, and the When in a stationary state, a transfer electric field is applied to the area where the reference toner image and the transfer material face each other, and as a result, out of the toner forming the reference toner image, toner corresponding to the area on which the transfer electric field acts is applied. is transferred onto the transfer material to form a toner image. Then, the transfer material to which the toner image has been transferred, or another transfer material to which the toner image has been transferred from the transfer material, is ejected from the apparatus, thereby allowing a person who adjusts the nip width, such as a service person, to , the width of the transfer electric field forming area can be confirmed. According to a second aspect of the present invention, the width of the toner image in the transfer material movement direction is detected by the width detection means, and the detection result is displayed on the display means. Claim 3
In the described invention, the width of the toner image in the transfer material moving direction is detected by the width detection means, and the width of the area on which the transfer electric field acts is adjusted by the adjustment means based on the detection result. According to a fourth aspect of the present invention, the width of the toner image in the transfer material movement direction is detected by the width detection means, and the intensity of the transfer electric field is controlled by the transfer electric field adjustment means based on the detection result. According to the fifth, sixth, or seventh aspect of the present invention, the width is detected by detecting the condition on the toner image carrier that has passed through a region on which the transfer electric field acts.

[0006]

[Embodiment] A first embodiment of this invention is shown in FIGS. 1(a) to 3.
, and FIG. 10. FIG. 10 is a schematic configuration diagram of a color electrophotographic copying machine (hereinafter referred to as a copying machine) according to an embodiment of the present invention. First, the general configuration of the entire copying machine will be explained. Around the photosensitive drum 1, which is a latent image carrier, there is a uniform charger 2, an exposure device (not shown) (exposure light from this is indicated by an arrow 3), a developing device 4, a belt bias roller 51, a backup roller 52, etc. An intermediate transfer device 5 including an intermediate transfer belt 53 that is stretched around the intermediate transfer device 5 and a cleaning device 6 are provided. Here, the exposure device is equipped with a filter means for color-separating the light image from the original on a contact glass (not shown), and the developing device 4 is equipped with a filter means for color-separating the light image from the original on a contact glass (not shown), and the developing device 4 is equipped with a filter means for color-separating the light image from the original on a contact glass (not shown).
A C developing device 41, an M developing device 42, and a Y developing device 43 are provided, each of which uses a developer. A paper bias roller 7 is opposed to the backup roller 52 of the intermediate transfer device 5 with the intermediate transfer belt 53 sandwiched therebetween. Registration rollers 8 are provided as transfer paper transport means for transporting the transfer paper. The belt bias roller 51 is made of an elastic material and is brought into contact with the photoreceptor drum 1 with a predetermined pressure, and the paper bias roller 7 is made of an elastic material and is brought into contact with the backup roller 52. By being brought into contact with each other with a predetermined pressure, a nip width is formed respectively. By adjusting this predetermined pressure, each nip width can be adjusted. Hereinafter, the nip width formed between the intermediate transfer belt 53 on the belt bias roller 51 and the photosensitive drum 1 will be referred to as the belt nip width, and the nip width formed between the intermediate transfer belt 53 on the paper bias roller 7 and the backup roller 52 will be referred to as the paper nip width. This is called the nip width.

Next, the operation during normal color copy formation will be explained. While rotating the photoreceptor drum 1, the photoreceptor on the surface is uniformly charged by the uniform charger 2, and an optical image from the document, which has been color-separated by the color separation filter, is formed on the charged photoreceptor. An electrostatic latent image is formed by imagewise exposure. This electrostatic latent image is converted into a toner image by the corresponding developing devices 41, 42, and 43, and the toner image is transferred from the photoreceptor drum 1 to the intermediate portion under a transfer electric field formed by applying a voltage to the belt bias roller 51. The toner image is transferred onto the transfer belt 53. In transferring the toner image from the photosensitive drum 1 to the intermediate transfer belt 53, the photosensitive drum 1 corresponds to a toner image carrier, and the intermediate transfer belt 53 corresponds to a transfer material. The above steps from exposing the color-separated original image to transferring the toner image onto the intermediate transfer belt 53 are performed for each color, and the toner images of each color are superimposed on the intermediate transfer belt 53. When the toner images of each color are superimposed on the intermediate transfer belt 53, the registration roller 8 is driven to convey the transfer paper to the contact area between the intermediate transfer belt 53 and the paper bias roller 7, and the paper bias roller 7 The superimposed toner images on the intermediate transfer belt 53 are transferred to a transfer paper under a transfer electric field formed by applying a voltage to the
Form a color copy. In this transfer from the intermediate transfer belt 53 to the transfer paper, the intermediate transfer belt 53 corresponds to a toner image carrier, and the transfer paper corresponds to a transfer material. The color copy formed as described above is discharged onto a paper discharge tray outside the machine (not shown).

In order to facilitate the adjustment of the nip width by a service person, this embodiment is provided with a nip width detection mode for detecting each of the nip widths, in addition to the above-mentioned normal color copy mode. be. The nip width detection mode will be described below with reference to FIGS. 1(a) to 3. This nip width detection mode can be selected and executed by operating a key on a manual operation panel (not shown) or a switch inside the copying machine. At this time, a selection may be made between belt nip width detection and paper nip width detection, or detection of both nip widths may be performed successively. First, detection of the belt nip width will be explained using FIG. 1(a) and FIG. 2. In the first step, a reference toner image having a predetermined width sufficiently wider than the nip width in the moving direction of the photoreceptor drum 1 is formed on the photoreceptor drum 1 (I in FIG. 1(a)). For this purpose, while rotating the photosensitive drum 1, uniformly charging the photosensitive drum 1, forming a latent image with the above-mentioned predetermined width, and converting this latent image into a toner image using one of the developing devices. do. Here, this latent image may be formed by removing static electricity from a part of the uniformly charged area other than the part where this latent image is formed, or by removing static electricity from the area on one side of the contact glass. A reference plate having a black portion of a predetermined width may be provided, and an image of the reference plate may be formed by exposing the uniformly charged photoreceptor drum 1 to light using an exposure optical system. Note that at this time, the belt bias roller 51 is
For those that are kept in contact with the specified pressure,
In order to reduce wear due to friction between the intermediate transfer belt 53 and the photoreceptor, it is desirable that the intermediate transfer belt 53 is also rotationally driven. Next, in the second step, the process waits for the reference toner image to reach a position straddling the belt nip width (hereinafter referred to as reaching the belt nip width) (see I in FIG. 1(a),
(The reference toner image is directed toward the belt nip width.) For this purpose, well-known timing control methods can be used. For example, in the case where the reference plate is exposed using a moving exposure optical system, the home position sensor detects that the optical system has started at the home position, counts the timing pulses from this time, and calculates the count value. Whether or not the reference toner image has reached the belt nip width is determined based on whether or not the reference toner image has reached a set count value determined in advance to reach the belt nip width. When the reference toner image reaches the belt nip width, in a third step, the rotation of the photosensitive drum 1 and the intermediate transfer belt is stopped, and in a fourth step, a predetermined transfer bias is applied to the belt bias roller 51 for a predetermined time. (Figure 1(a)
) shows a state in which the reference toner image is transferred with the belt nip width). As a result, a toner image having a width corresponding to the belt nip width is transferred onto the transfer belt. This predetermined time is determined in advance through experiments as a time sufficient to transfer the toner on the photoreceptor drum 1 to the transfer belt, but normally several milliseconds is sufficient. Next, in a fifth step, the rotation of the photosensitive drum 1 and the intermediate transfer belt 53 is restarted,
In the sixth step, as in the normal copy mode, while rotating the intermediate transfer belt 53, the transfer paper fed to the paper nip width by the registration roller 8 is transferred by the paper bias roller 7 to which a transfer bias is applied.
The toner image on the intermediate transfer belt 53 is transferred, and the transfer paper is discharged onto a paper discharge tray outside the machine (I in FIG. 1(a)).
(II shows a state in which the toner image on the intermediate transfer belt 53 is directed toward the paper nip width, and IV in FIG. 1A shows a state in which the toner image on the transfer paper is directed toward the paper ejection tray). The width of the toner image formed on the transfer paper as described above is
Since the width corresponds to the belt nip width, the belt nip width can be easily determined by measuring it by the service person who is responsible for adjusting the nip width, making it easier to adjust the belt nip width. Become.

Next, detection of the paper nip width will be explained using FIG. 1(b) and FIG. 3. In the first step,
A reference toner image having a predetermined width sufficiently wider than the paper nip width in the moving direction of the photoreceptor drum 1 is formed on the intermediate transfer belt 53 (I in FIG. 1(b) shows that the toner image on the photoreceptor is Condition toward the nip width, Figure 1
(b) II shows a state in which the reference toner image on the intermediate transfer belt 53 is directed toward the paper nip width). For this purpose, while rotating the photosensitive drum 1, uniformly charging the photosensitive drum 1, forming a latent image with the above-mentioned predetermined width, and converting this latent image into a toner image using one of the developing devices. Then, while the photoreceptor drum 1 and the intermediate transfer belt 53 continue to rotate, the toner image is transferred from the photoreceptor drum 1 to the intermediate transfer belt 53 using the belt bias roller 51 to which a transfer bias is applied, and a reference image is obtained. Use it as a toner image. here,
Formation of the latent image can be performed in the same manner as in the belt nip adjustment mode described above. This intermediate transfer belt 5
The reference toner image on No. 3 is used to transfer the toner image from the photoreceptor drum 1 to the intermediate transfer belt 53 in the same manner as in the normal copy mode.
Since this is done while rotating, the entire width of the toner image on the photosensitive drum 1 is transferred onto the intermediate transfer belt 53, and like the latent image, it has a width sufficiently wider than the paper nip width. are doing. Then, in the second step,
Wait until the registration timing to start the rotation of the registration roller 8 is reached, and when the registration timing comes, the rotation of the registration roller 8 is started in a third step. Then,
In the fourth step, the process waits for the reference toner image on the intermediate transfer belt 53 to reach a position across the paper nip width (hereinafter referred to as reaching the paper nip width). For this purpose, a well-known registration timing control method can be used. When the reference toner image on the intermediate transfer belt 53 reaches the paper nip width, the rotation of the registration roller 8, photosensitive drum 1, and intermediate transfer belt 53 is stopped in a fifth step, and the rotation of the paper bias roller 7 is stopped in a sixth step. A predetermined transfer bias is applied for a predetermined time (Fig. 1(b)
) shows a state in which the reference toner image on the intermediate transfer belt 53 is transferred with the paper nip width). As a result, a toner image having a width corresponding to the paper nip width is transferred onto the transfer belt. This predetermined time is also
A sufficient time for transferring the toner on the transfer paper 3 is determined in advance through experiments, but normally several milliseconds is sufficient. Next, in a seventh step, the rotation of the registration roller 8, photosensitive drum 1, and intermediate transfer belt 53 is resumed, and in an eighth step, the transfer paper is placed on a paper output tray outside the machine, as in the normal copy mode. (at IV in Figure 1(b),
(This shows the state in which the toner image on the transfer paper is facing the paper output tray.) The width of the toner image formed on the transfer paper as described above corresponds to the paper nip width, so a nip width adjuster such as a service person can easily adjust the paper nip width by measuring this. I can know,
Paper nip width adjustment work becomes easier.

Next, a second embodiment of the present invention will be described. In the first embodiment, an adjuster such as a service person measures the transfer paper onto which a toner image having a width corresponding to the nip width to be adjusted is transferred. The present embodiment is intended to eliminate the troublesome measurement by the adjuster. To this end, in this embodiment, the width of the toner image corresponding to the nip width to be adjusted is detected using an optical sensor or a potential sensor (hereinafter referred to as sensor 10) that detects the charge on the toner. , the detection results are displayed on a display means on a manual operation panel (not shown). The toner image width L using the sensor 10 is detected during the time t during which the sensor 10 detects the presence of the toner image (for example, in the case of a reflective optical sensor, the period during which reflected light is decreasing). is calculated by multiplying by the moving speed v of the toner image carrier (L=v·t, see FIG. 4). If the sensor 10 is placed on the transfer paper conveyance path from the paper nip to the paper ejection tray (for example, Fig. 1(b)
) can be provided at position A indicated by a broken line in IV of ), and can be used both for detecting the width of the toner image in the belt nip width adjustment mode and for detecting the width of the toner image in the paper nip width adjustment mode. The sequence control will be similar to the example. Detection of the width of the toner image in the belt nip width adjustment mode can also be performed by arranging a sensor on the intermediate transfer belt 53 from the belt nip to the paper nip (for example, at the position indicated by the broken line III in FIG. 1(a)). (provided in B). According to this, since the width of the toner image on the intermediate belt is detected according to the belt nip width, the sequence control in this case is as follows in the first embodiment.
It is also possible to omit the step of transferring the toner image onto the transfer paper, thereby reducing the consumption of the transfer paper. If the step of transferring the toner image onto the transfer paper is omitted, the detected toner image on the intermediate transfer belt 53 may be removed by a cleaning device (not shown) for the intermediate transfer belt 53, or by a belt bias roller. The polarity of the voltage applied to the photosensitive drum 51 may be reversed to transfer it again to the photosensitive drum 1, and the cleaning device 6 for the photosensitive drum 1 may remove it. The width of the toner image in the paper nip width adjustment mode can also be detected by arranging the sensor 10 on the paper bias roller 7. The sequence control in this case is to transfer the reference toner image on the intermediate transfer belt 53 directly onto the surface of the paper bias roller 7 without feeding the transfer paper to the paper nip, and to transfer the toner image on the paper bias roller 7 directly. This will be detected by the sensor 10. According to this, consumption of transfer paper can be suppressed.

Next, a third embodiment of the present invention will be explained using FIGS. 5 to 7. In this embodiment, the nip width to be adjusted is automatically adjusted using the result of detecting the width of the toner image using the sensor 10 in the second embodiment. To this end, this embodiment is provided with a nip width adjustment mechanism. 5 and 6 show an example of a belt nip width adjustment mechanism and a paper nip width adjustment mechanism using a cam mechanism. Reference numeral 20 indicates an eccentric cam, and 21 indicates an eccentric cam motor which is an eccentric cam driving member. By driving and controlling the eccentric cam motor 21 by a control unit to change the rotation angle of the eccentric cam 20, the nip width is changed. Figure 7 shows
FIG. 3 is a flowchart of control for automatically adjusting the nip width. FIG. First, in the first step, a toner image to be measured is formed and its width L is measured in the same manner as in the second embodiment. Then,
In the second step, it is determined whether the detected width L is larger than the set value L of the measured toner image width corresponding to the desired nip width. If the detected width L is larger than the set value L, in the third step, the eccentric cam motor 21 is moved in the direction where the nip width becomes smaller.
After rotating by a predetermined angle θ, the process returns to the first step. If it is determined in this second step that the detection width L is not larger than the set value L, in the fourth step it is determined whether the detection width L is smaller than the set value L, and the detection width L is determined to be the set value. L
If it is smaller, the eccentric cam motor 21 is rotated by a predetermined angle θ in the direction in which the nip width becomes larger, and then the process returns to the first step. Thereafter, in the fourth step, the formation and measurement of the measurement toner image and the rotation of the eccentric cam motor 21 by a predetermined angle θ are repeated until it is determined that the detection width L is not smaller than the set value L, and in the fourth step, the detection If it is determined that the width L is not smaller than the set value L, the detected width L becomes the set value L.
This means that they match, so we finish adjusting the nip width. The automatic nip width adjustment shown in FIG. 7 is performed for each nip width.

Next, a fourth embodiment of the present invention will be explained using FIGS. 8 and 9. In the third embodiment described above, the nip width, which is the adjustment target, is automatically adjusted using the width detection result of the measured toner image, whereas this embodiment uses the width detection result of the measured toner image. is used to control the intensity of the transfer electric field. This takes advantage of the fact that the transferability changes depending on the size of the nip width, which can be controlled to a desired transferability by changing the intensity of the transfer electric field. In this embodiment, the transfer bias applied to each bias roller 51, 7 is changed in four steps depending on the detected nip width. That is, when the detected nip width L is smaller than the predetermined nip width L1, the transfer bias value is set to V1, and when the detected nip width L is greater than or equal to the predetermined nip width L1 and smaller than the predetermined nip width L2, the transfer bias value is set to V1.
2, when the detected nip width L is greater than or equal to the predetermined nip width L2 and smaller than the predetermined nip width L3, the transfer bias is set to V3, and when the detected nip width L is greater than or equal to the predetermined nip width L3, the transfer bias value is switched to V4. do. These,L1,
L2, L3, V1, V2, V3, and V4 are determined in advance through experiments. FIG. 8 is a flowchart of control of this transfer bias value switching setting. First, in the first step, a toner image to be measured is formed and its width L is measured in the same manner as in the second embodiment. Next, in the second to fourth steps, it is determined which of the above ranges the detected nip width L is in, and in the fifth to eighth steps, the transfer bias value is set to correspond to each range. hand,
Ends switching setting control. The above control is performed for each nip width.

FIG. 9 shows the control section 11 in this embodiment,
Sensor 10 for nip width detection, power supply 1 for transfer bias
This shows the connection relationship with 2. The control unit 11 mainly includes a microprocessor (CPU) 13, a ROM (read-only memory) 14, a RAM (read-write memory) 15, and an interface (I/O) 16. , the output from the nip width detection sensor (optical sensor or potential sensor) 10 is input as a digital signal via an A/D converter (not shown), and from the interface 16, a D/A converter (not shown) is input. A transfer bias value signal is outputted to the transfer bias power supply 12 via the transfer bias power source 12. The ROM 14 stores the control program described above.

In the above embodiment, the roller is made of an elastic material to form the nip width, but instead of this, an intermediate transfer belt or the like may be wound around the roller. For example, in the case of using a belt-shaped photoreceptor, the nip may be formed by wrapping the photoreceptor belt around an intermediate transfer roller or a roller that supports the intermediate transfer belt. Furthermore, although each of the above embodiments uses an intermediate belt as an intermediate transfer member, the toner image formed on the latent image carrier is directly transferred to the final image without using such an intermediate transfer member. It can also be applied to transfer materials.

Furthermore, in the second to fourth embodiments, in which a predetermined width of the toner image is detected by a sensor and a display is performed using the detection result, the width detection means uses the optical density or potential of the toner image itself. However, instead of this, an optical sensor or a potential sensor is used to detect the surface of the photosensitive drum 1 or intermediate transfer belt 53, which is the toner image carrier after the toner image has been transferred. However, the predetermined width of the toner image may be detected from the trace after the toner image has been transferred. Figure 11 shows how to detect belt nip width.
Instead of detecting the toner image on the intermediate transfer belt, a reflective optical sensor detects the surface of the photosensitive drum 1 after the toner image has passed through the belt nip width and been transferred to the intermediate transfer belt. FIG. 6 is an explanatory diagram when detecting a predetermined width of a toner image. In the figure, 1 is a photosensitive drum;
a is a trace of a toner image transferred to the intermediate transfer belt side with no toner present, and b is a trace from the belt nip width to the intermediate transfer belt moving direction with the photoreceptor drum 1 and the intermediate transfer belt 53 stopped. This shows the toner portion that was not transferred to the intermediate transfer belt 53 as a result of being deviated to the upstream side and the downstream side, respectively. The width of this trace a in the intermediate transfer belt movement direction matches that of the toner image on the intermediate transfer belt. Therefore, instead of directly detecting the predetermined width of the toner image on the intermediate transfer belt, the predetermined width of the trace is detected, and thereby the predetermined width of the toner image on the intermediate transfer belt is detected. be. The lower part of the figure shows the output of the reflective optical sensor corresponding to each value on the upper photoreceptor drum. The predetermined width L of the trace a is determined by multiplying the time t during which this sensor output is at a relatively high level by the circumferential speed v of the photoreceptor drum surface when the photoreceptor drum surface is detected by the optical sensor. That is, the predetermined width of the toner image on the intermediate transfer belt can be detected. In order to detect such a belt nip width, an optical sensor or a potential sensor is used, for example, as shown in FIG. 1(a).
As indicated by a broken line B2, it is placed on the photosensitive drum 1 downstream from the belt nip width in the photosensitive drum movement direction and upstream from the cleaning device 6 in the same direction. In detecting the paper nip width, an optical sensor or a potential sensor is used, for example, at a position A2 indicated by a broken line in IV in FIG. A predetermined width of the toner image can be detected in the same manner as the belt nip width detection described above by placing it on the intermediate transfer belt where traces remain without being cleaned after the toner image is transferred to the transfer paper.

[0016]

As described above, according to the present invention, when the transfer material faces the reference toner image, the toner image carrier and the transfer material are kept stationary, and the reference toner image and the transfer material are By applying a transfer electric field to the opposing area, a toner image is formed by transferring toner according to the area where the transfer electric field acts, so this toner image can be used to determine the width of the area where the transfer electric field acts. This has the excellent effect of reducing the effort of adjusting the nip width by an adjuster such as a service person.

[Brief explanation of the drawing]

FIG. 1 (a) is a process diagram for explaining each process in belt nip adjustment mode, and (b) is a process diagram for explaining each process in paper nip adjustment mode.

FIG. 2 is a flowchart of control in a belt nip width adjustment mode according to the first embodiment.

FIG. 3 is a flowchart of control in the paper nip width adjustment mode according to the first embodiment.

FIG. 4 is a diagram for explaining width detection of a toner image using a sensor 10 in a second embodiment.

FIG. 5 is a schematic configuration diagram of a belt nip width adjustment mechanism in a second embodiment.

FIG. 6 is a schematic configuration diagram of a paper nip width adjustment mechanism in a second embodiment.

FIG. 7 is a flowchart of control in the nip width adjustment mode according to the third embodiment.

FIG. 8 is a flowchart of control in a nip width adjustment mode according to a fourth embodiment.

FIG. 9 is a circuit diagram showing a connection relationship of a control system in a fourth embodiment.

FIG. 10 is a schematic configuration diagram of a color copying machine to which the present invention can be applied.

FIG. 11 is an explanatory diagram of a nip width detection device according to a modified example.

[Explanation of symbols]

1 Photoreceptor drum
, 51 Belt bias roller 52 Backup roller
, 53 Intermediate transfer belt 7 Paper bias roller ,
8 Registration roller

Claims (7)

[Claims] 1. An image forming apparatus that transfers a toner image on a toner image carrier to a transfer material under the action of a transfer electric field, comprising:
means for forming a reference toner image having a predetermined width on the toner image carrier in the moving direction of the toner image carrier; a means for bringing the transfer material into a stationary state; a means for applying a transfer electric field to a region where the reference toner image and the transfer material face each other when the reference toner image is in the stationary state; , at least one of the transfer material to which the toner image formed by the transferred toner is transferred according to the area on which the transfer electric field acts, and another transfer material to which the toner image is transferred from the transfer material. An image forming apparatus comprising: a discharge means for discharging the image to the outside of the apparatus. 2. An image forming apparatus that transfers a toner image on a toner image carrier to a transfer material under the action of a transfer electric field, comprising:
means for forming a reference toner image having a predetermined width on the toner image carrier in the moving direction of the toner image carrier;
means for bringing the toner image carrier and the transfer material into a relatively stationary state when the transfer material faces the reference toner image; a means for applying a transfer electric field to a region facing the reference toner image; and a means for applying a transfer electric field to a region facing the reference toner image; An image forming apparatus comprising: a width detecting means for detecting a width in a moving direction; and a display means for displaying a detection result by the width detecting means. 3. An image forming apparatus that transfers a toner image on a toner image carrier to a transfer material under the action of a transfer electric field, comprising:
means for forming a reference toner image having a predetermined width on the toner image carrier in the moving direction of the toner image carrier;
means for bringing the toner image carrier and the transfer material into a relatively stationary state when the transfer material faces the reference toner image; a means for applying a transfer electric field to an area facing the material; and a means for applying a transfer electric field to an area facing the reference toner image, and transferring a toner image formed by toner transferred according to an area on which the transfer electric field acts among the toner forming the reference toner image. An image forming apparatus comprising: a width detecting means for detecting a width in a material moving direction; and an adjusting means for adjusting the width of an area on which the transfer electric field acts based on a detection result by the width detecting means. 4. An image forming apparatus that transfers a toner image on a toner image carrier to a transfer material under the action of a transfer electric field, comprising:
means for forming a reference toner image having a predetermined width on the toner image carrier in the moving direction of the toner image carrier;
means for bringing the toner image carrier and the transfer material into a relatively stationary state when the transfer material faces the reference toner image; a means for applying a transfer electric field to a region facing the reference toner image; and a means for applying a transfer electric field to a region facing the reference toner image; An image forming apparatus comprising: width detecting means for detecting a width in a moving direction; and transfer electric field adjusting means for controlling the intensity of the transfer electric field based on a detection result by the width detecting means. 5. The width detecting means detects the width by detecting a state on the toner image carrier that has passed through a region on which the transfer electric field acts. Image forming device. 6. The width detecting means detects the width by detecting a state on the toner image carrier that has passed through a region on which the transfer electric field acts. Image forming device. 7. The width detecting means detects the width by detecting a state on the toner image carrier that has passed through a region on which the transfer electric field acts. Image forming device.