JP2004078016A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device for forming an image by secondary transferring of a primary transfer image to transfer paper inexpensively and stably. <P>SOLUTION: A toner image is transferred in a primary transfer position as the primary transfer image from a photoreceptor drum to an intermediate transfer belt 11 driven in a prescribed direction. In a secondary transfer position in a downstream of the primary transfer position, the primary transfer image is transferred from the intermediate transfer belt to the transfer paper as a secondary transfer image. The transfer paper positioned in a downside of the intermediate transfer belt is controlled to be carried to the secondary transfer position. A detecting sensor is arranged in a downside of a carrier path through which the transfer paper passes. While the transfer paper is detected and a transfer paper detection signal is transmitted, when the transfer paper is not present, a position detection pattern formed in the intermediate transfer belt is detected and a pattern detection signal is transmitted. A drive controller 24 determines carrier speed of the intermediate transfer belt according to the pattern detection signal, while carrier speed of the transfer paper is determined according to the transfer paper detection signal. Drive of the intermediate transfer belt and carriage of the transfer paper are adjusted corresponding to paper according to the transfer paper carrier speed and the intermediate transfer belt carrier speed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine or a printer using an electrophotographic method, and more particularly, to an image forming apparatus for transferring a toner image transferred onto an intermediate transfer member such as an intermediate transfer belt onto transfer paper (recording paper). It concerns the device.
[0002]
[Prior art]
Generally, in an image forming apparatus including an intermediate transfer member such as an intermediate transfer belt, a toner image (1) transferred from a photosensitive drum serving as an image carrier onto an intermediate transfer member at a primary transfer portion (primary transfer position). The secondary transfer image (secondary transfer image) is secondarily transferred from an intermediate transfer body to transfer paper by a secondary transfer roller or the like at a secondary transfer portion (secondary transfer position) to form an image. In such an image forming apparatus, at the time of the secondary transfer, in order for the primary transfer image transferred to the intermediate transfer member to be stably transferred to the transfer paper by the secondary transfer unit, the primary transfer image is formed by the second transfer. It is necessary to control the timing of reaching the next transfer section and the timing of the transfer paper reaching the secondary transfer section (that is, sheet feeding timing).
[0003]
For this reason, the conventional image forming apparatus includes an image alignment sensor for detecting the position of the primary transfer image transferred to the intermediate transfer member (the position on the intermediate transfer member), and also includes a leading edge or a trailing edge of the transfer paper. A transfer paper detection sensor for detecting the end is provided, and the drive of the intermediate transfer body and the drive of the transfer paper transport device are controlled in accordance with the detection results obtained by these sensors, so that the primary transfer image reaches the secondary transfer unit. The timing and the timing at which the transfer paper reaches the secondary transfer unit are adjusted.
[0004]
[Problems to be solved by the invention]
However, as described above, the conventional image forming apparatus includes two sensors, namely, an image alignment sensor and a transfer paper detection sensor, and drives the intermediate transfer body and transfers the transfer paper in accordance with the detection result by these sensors. Is inevitably controlled, and the number of parts inevitably increases, and the control becomes complicated, resulting in an increase in cost.
[0005]
In addition, for example, when an intermediate transfer belt is used as an intermediate transfer member, the diameter of a drive roller that drives the intermediate transfer belt inevitably occurs in the manufacturing process. On the other hand, the diameter of the transport roller used in the transfer paper transport device that transports the transfer paper also varies in the manufacturing process. As a result, a variation occurs in the transport speed (rotation speed) of the intermediate transfer belt and the transport speed of the transfer paper. As described above, even if the driving of the intermediate transfer belt and the conveyance of the transfer paper are controlled, the conveyance speed of the intermediate transfer belt and the conveyance speed of the transfer paper vary, so that the primary transfer image is transferred to the secondary transfer unit. It is difficult to accurately adjust the timing of the transfer and the timing at which the transfer paper reaches the secondary transfer portion, and there is a problem that the secondary transfer cannot be performed stably.
[0006]
In particular, in a printer in which the distance from the primary transfer section to the secondary transfer section and the distance from the transfer paper transport roller to the secondary transfer section are long, the primary transfer image may not be secondary due to the above-described variation. The timing at which the transfer sheet reaches the transfer section and the timing at which the transfer sheet reaches the secondary transfer section may be greatly deviated, and as a result, the position of the secondary transfer image on the transfer sheet and the secondary transfer magnification vary greatly.
[0007]
In order to suppress the above-described variation, it is necessary to extremely reduce the tolerance of the roller diameter of the intermediate transfer body driving roller, the transfer paper transport roller, and the like. There is a problem that costs increase.
[0008]
SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of inexpensively and stably secondary-transferring a primary transfer image onto transfer paper to form an image.
[0009]
[Means for Solving the Problems]
According to the present invention, an image carrier on which a toner image corresponding to image data is formed, and the toner image is transferred as a primary transfer image from the image carrier at a primary transfer position under drive control in a predetermined direction. And a transfer means for transferring the primary transfer image from the intermediate transfer body to a transfer sheet as a secondary transfer image at a secondary transfer position located downstream of the primary transfer position. An image forming apparatus for controlling the transfer of the transfer sheet to the secondary transfer position to form an image, wherein the transfer sheet is detected and a transfer sheet detection signal is transmitted; A detection sensor that detects a position detection pattern formed on the transfer paper and sends a pattern detection signal, and adjusts a variation between the intermediate transfer body and the transfer paper according to the transfer paper detection signal and the pattern detection signal. Adjustment means The image forming apparatus is obtained which is characterized by having a.
[0010]
In this way, the transfer paper is detected by one detection sensor and the transfer paper detection signal is sent, and if there is no transfer paper, the position detection pattern formed on the intermediate transfer body is detected and the pattern detection signal is sent. In this way, the variation between the intermediate transfer body and the transfer paper is adjusted according to the transfer paper detection signal and the pattern detection signal, so that the primary transfer image can be stably inexpensively and transferred to the transfer paper. The next transfer can be performed.
[0011]
According to the present invention, an image carrier on which a toner image corresponding to image data is formed, and the toner image is transferred as a primary transfer image from the image carrier at a primary transfer position under drive control in a predetermined direction. And a transfer means for transferring the primary transfer image from the intermediate transfer body to a transfer sheet as a secondary transfer image at a secondary transfer position located downstream of the primary transfer position. An image forming apparatus for controlling the transfer of the transfer sheet to the secondary transfer position to form an image, wherein the transfer sheet is detected and a transfer sheet detection signal is transmitted; A detection sensor for detecting a position detection pattern formed on the transfer paper and transmitting a pattern detection signal; and obtaining a transfer speed of the transfer paper as a calculated transfer paper transport speed in accordance with the transfer paper detection signal and responding to the pattern detection signal. The image forming apparatus is obtained and having a velocity calculating means for calculating the transport speed of the intermediate transfer member as calculated intermediate transfer member conveying speed Te.
[0012]
In this way, the transfer paper is detected by one detection sensor and the transfer paper detection signal is sent, and if there is no transfer paper, the position detection pattern formed on the intermediate transfer body is detected and the pattern detection signal is sent. As a result, the transfer speed of the transfer sheet is calculated as the transfer paper transfer speed in accordance with the transfer sheet detection signal, and the transfer speed of the intermediate transfer member is calculated as the calculated intermediate transfer member transfer speed in accordance with the pattern detection signal. Then, the drive of the intermediate transfer member and the transfer of the transfer sheet can be adjusted according to the calculated transfer sheet transfer speed and the calculated intermediate transfer member transfer speed, so that the primary transfer image can be transferred stably at low cost. Secondary transfer to paper can be performed.
[0013]
For example, the transfer sheet is located below the intermediate transfer member, the detection sensor is disposed below a transfer path through which the transfer sheet passes, and further, the calculated transfer sheet transfer speed and the calculated intermediate Control means for adjusting driving of the intermediate transfer body and conveyance of the transfer paper according to the transfer body conveyance speed may be provided.
[0014]
In the present invention, the control unit determines the timing at which the primary transfer image reaches the secondary transfer position so that the calculated transfer paper transport speed and the calculated intermediate transfer body transport speed have a predetermined relationship. The timing at which the transfer paper reaches the secondary transfer position is controlled. If the timing control is performed in this manner, the primary transfer image can be transferred to the transfer paper with high accuracy even if the transfer speed of the transfer paper and the transfer speed of the intermediate transfer body vary.
[0015]
For example, the detection sensor has a light emitting unit and a light receiving unit, and the reflected light is reflected by the intermediate transfer body or reflected by the transfer paper according to the distribution of the amount of the reflected light received by the light receiving unit. When the reflected light is the light reflected on the transfer paper, the reflected light is recognized as the transfer paper detection signal, and the reflected light is the light reflected on the intermediate transfer body. And determining means for recognizing the reflected light as the pattern detection signal.
[0016]
According to the present invention, the speed calculating means obtains the calculated transfer paper transport speed according to the time at which the leading edge of the transfer paper is detected and the time at which the rear end of the transfer paper is detected, and calculates the leading edge of the position detection pattern. The calculated intermediate transfer body transport speed is determined according to the time at which is detected and the time at which the rear end of the position detection pattern is detected. In this way, the calculated transfer paper transport speed is determined according to the time at which the leading edge of the transfer paper is detected and the time at which the trailing edge of the transfer paper is detected, and the time at which the leading edge of the position detection pattern is detected and the trailing edge of the position detection pattern are determined. If the calculated intermediate transfer body transport speed is obtained in accordance with the time at which is detected, the transport speed of the transfer paper and the transport speed of the intermediate transfer body can be easily controlled.
[0017]
Further, in the present invention, the intermediate transfer member is an intermediate transfer belt, and the intermediate transfer belt is suspended in an inverted triangular shape by at least three suspension rollers, and a suspension located at a lowermost position among the three rollers The position of the roller is the secondary transfer position. In this way, using the intermediate transfer belt as the intermediate transfer body, the intermediate transfer belt is suspended in an inverted triangular shape by at least three suspension rollers, and the position of the suspension roller located at the lowermost side of the three rollers is set to two. If the next transfer position is set, the position detection pattern on the transfer paper and the intermediate transfer belt can be accurately detected by one detection sensor.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings. Note that the dimensions, materials, shapes, relative arrangements, and the like of the components in the illustrated example are not intended to limit the scope of the present invention, but are merely illustrative examples, unless otherwise specified.
[0019]
Referring to FIG. 1, here, an image forming apparatus using an intermediate transfer belt as an intermediate transfer body will be described. The illustrated image forming apparatus has an intermediate transfer belt 11, and color developing units 12 to 15 are arranged along the intermediate transfer belt 11. In the illustrated example, the yellow developing unit 12, the magenta developing unit 13, the cyan developing unit 14, and the black developing unit 15 are arranged in this order along the rotation direction of the intermediate transfer belt 11 (the direction indicated by the solid line arrow).
[0020]
Each of the color developing units 12 to 15 is provided with a photosensitive drum 12 a to 15 a, respectively. Although not shown, a charger, an exposure device, a developing device, a cleaning unit, and the like are arranged around the photosensitive drums 12 a to 15 a. ing. Then, the photosensitive drums 12a to 15a are exposed by image data for each color to form an electrostatic latent image on the photosensitive drums 12a to 15a. It is an image. The toner remaining on the photosensitive drums 12a to 15a is cleaned by the cleaning unit.
[0021]
Primary transfer rollers 16a to 16d are arranged opposite to the photoconductor drums 12a to 15a, and the respective color toner images are sequentially superimposed on the intermediate transfer belt 11 and transferred by the primary transfer rollers 16a to 16d. This is a transfer image. A secondary transfer roller 17 is disposed downstream of the intermediate transfer belt 11, and a backup roller (secondary transfer opposing roller) 18 is disposed opposite to the secondary transfer roller 17.
[0022]
As shown in FIG. 1, the intermediate transfer belt 11 is suspended with a belt transport roller (drive roller) 19, a tension roller 20, and a backup roller 18 as suspension rollers. 11 is driven in a predetermined direction (the direction indicated by the solid arrow in the figure). Further, a predetermined tension is applied to the intermediate transfer belt 11 by the tension roller 20. As shown in the drawing, the backup roller 18 is disposed below the belt transport roller 19 and the tension roller 20 and close to the tension roller 20. As a result, the intermediate transfer belt 11 is suspended in an inverted triangular shape having the rotation axes of the backup roller 18, the belt conveyance roller 19, and the tension roller 20 as vertices.
[0023]
The transfer paper P is transported to a nip portion between the intermediate transfer belt 11 and the secondary transfer roller 17 by a pair of transfer paper transport rollers 21, and the primary transfer image on the intermediate transfer belt 11 is transferred to the secondary transfer image on the transfer paper P. Is transcribed as Thereafter, the transfer sheet P is transported to a fixing unit (not shown), where the secondary transfer image is fixed on the transfer sheet P. Then, the transfer paper P is discharged.
[0024]
The belt transport roller 19 and the transfer paper transport roller 21 are driven by a belt drive motor 22 and a transfer paper transport motor 23, respectively. The belt drive motor 22 and the transfer paper transport motor 23 are controlled by a drive controller 24. As shown in FIG. 1, a detection sensor (for example, an optical sensor) 25 is provided below the transfer path of the transfer paper P (transfer paper transfer path) and near the nip portion. 25 is connected to the drive control device 24. The intermediate transfer belt 11 is located above the transfer paper transport path.
[0025]
The detection sensor 25 detects the transfer paper P passing through the transfer paper transport path. For example, the detection sensor 25 has a light emitting unit 25a and a light receiving unit 25b as shown in FIG. Reference numeral 25b receives the reflected light of the light transmitted from the light emitting unit 25a. Now, when the transfer paper P attempts to pass directly above the detection sensor 25, the light emitted from the light emitting unit will be reflected at the leading end of the transfer paper P, so that the amount of light received by the light receiving unit changes greatly. (In this case, the amount of received light greatly increases). The detection sensor 25 gives this change in the amount of received light to the drive control device 24 as a received light amount detection signal (electrical signal: the received light amount detection signal is a transfer paper detection signal). The leading edge of the transfer sheet P is known by a signal (that is, an increase in the amount of received light), and the time at which the leading end of the transfer sheet P is detected is obtained from a built-in timer. tf).
[0026]
On the other hand, even when the transfer paper P passes just above the detection sensor 25, the amount of light received by the light receiving unit changes greatly (in this case, the amount of received light greatly decreases). Therefore, the drive control device 24 knows the trailing edge of the transfer sheet P by the received light amount detection signal (that is, the decrease in the received light amount). Then, the drive control unit 24 obtains the time at which the trailing edge of the transfer sheet P is detected from the built-in timer (here, the time at which the trailing edge of the transfer sheet P is detected is tb). Note that, when the leading end of the transfer sheet P is detected, timing may be started, and the time until the trailing end of the transfer sheet is detected may be counted.
[0027]
Then, the drive control device 24 obtains the transport speed Vp of the transfer paper P. That is, the drive control device obtains the transfer speed of the transfer paper as the calculated transfer paper transfer speed based on the times tb and tf (speed calculation means). As described above, since the transfer paper transport motor 23 is controlled by the drive control device 24, that is, the drive control device 24 controls the rotation speed of the transfer paper transport motor 23. Then, Vp = 1 / (tb−tf) = (Vfm × α). Here, α represents the speed ratio between the transfer paper transport motor 23 and the transfer paper transport roller 21, and l represents the length of the transfer paper (paper).
[0028]
By the way, as shown in FIG. 2, when the transfer paper P does not exist in the transfer paper conveyance path, that is, when the transfer paper P does not exist on the detection sensor 25, the light from the detection sensor 25 The light is reflected by the belt 11. Also at this time, the drive control device 24 is supplied with the received light amount detection signal output from the detection sensor 25 (this received light amount detection signal is a pattern detection signal), as shown in FIG. At the position where the detection sensor 25 is disposed, the intermediate transfer belt 11 is inclined, so that the light emitted from the detection sensor 25 is reflected in a direction different from the case where the transfer paper P exists. .
[0029]
In other words, the light reception amount distribution differs between the reflected light reflected by the transfer paper P (indicated by a solid arrow in FIG. 3) and the reflected light reflected by the intermediate transfer belt 11 (indicated by a broken arrow in FIG. 3). (That is, the position where the amount of received light is maximum is shifted). Therefore, as shown in FIG. 3, if a light receiving unit in which a plurality of light receiving elements (not shown) are arranged in the transport direction of the intermediate transfer belt 11 is used as the light receiving unit 25b, the light receiving amount distribution becomes as described above. As a result, the drive control device 24 can determine whether the received light amount detection signal is due to the reflection from the transfer paper P or the reflection from the intermediate transfer belt 11.
[0030]
In the above example, whether the transfer paper P or the intermediate transfer belt 11 is determined based on the received light amount distribution. However, whether the transfer paper P is the intermediate transfer belt 11 is determined based on the received light amount. You may make it. That is, in the illustrated example, since the transfer paper P is closer to the detection sensor 25 than the intermediate transfer belt 11, the amount of light received by the transfer paper P is greater than the amount of light received by the intermediate transfer belt 11. . Therefore, a light reception amount threshold is set in advance, and when the light reception amount of the reflected light exceeds the light reception amount threshold, the reflected light may be determined to be light reflected by the transfer paper P.
[0031]
For example, a position detection pattern (toner detection pattern) is formed on the intermediate transfer belt 11, and the position detection pattern is formed in a predetermined area on the intermediate transfer belt 11. That is, the position detection pattern is formed along the transport direction (rotation direction) of the intermediate transfer belt 11.
[0032]
Now, when the tip of the position detection pattern passes over the detection sensor 25, the amount of light received by the light receiving portion changes according to the position detection pattern (in general, since this position detection pattern is black, Volume is reduced). The drive control device 24 knows the intermediate transfer belt 11 according to the received light amount detection signal, that is, from the received light amount distribution, and also knows the leading end of the position detection pattern by decreasing the received light amount. Then, the time at which the tip of the position detection pattern is detected is obtained from the built-in timer (here, the time at which the tip of the position detection pattern is detected is Tf).
[0033]
On the other hand, even when the position detection pattern passes over the detection sensor 25, the amount of light received by the light receiving unit changes (in this case, the amount of received light increases). Therefore, the drive control device 24 knows the rear end of the position detection pattern based on the received light amount detection signal (that is, by increasing the received light amount). Then, the drive control device 24 obtains the time at which the rear end of the position detection pattern is detected from the built-in timer (here, the time at which the rear end of the position detection pattern is detected is Tb). Note that, when the leading end of the position detection pattern is detected, timing may be started and the time until the trailing end of the position detection pattern is detected may be counted.
[0034]
Then, the drive control device 24 determines the transport speed Vb of the intermediate transfer belt 11 according to the detection time of the position detection pattern. That is, the drive control device 24 obtains the transport speed of the intermediate transfer belt 11 as the calculated intermediate transfer body transport speed based on the times Tb and Tf (speed calculating means). As described above, since the belt drive motor 22 is controlled by the drive control device 24, that is, the drive control device 24 controls the rotation speed of the belt drive motor 22, so that this rotation speed is Vbm. Vb = L / (Tb−Tf) = βVbm. Β represents the speed ratio between the belt drive motor 22 and the belt transport roller 19, and L represents the interval between the position detection patterns.
[0035]
As described above, since the roller diameters of the belt transport roller 19 and the transfer paper transport roller 21 have variations, respectively, the transport speeds Vb and Vp vary. Therefore, here, the drive control device 24 controls the drive of the transfer paper transport motor 23 and the belt drive motor 22 so that Vp = γVb (γ is a constant) (that is, the transport speed Vp and the transport speed Vb are previously set). The drive control device 24 controls the drive of the transfer sheet transport motor 23 and the belt drive motor 22 so as to have a predetermined relationship (control means).
[0036]
As described above, the drive control device 24 obtains the transport speeds Vp and Vb, and sets the transport speeds Vp and Vb to a predetermined relationship (Vp = γVb) so that the primary transfer image is transferred to the secondary transfer unit. The transport speeds Vp and Vb are adjusted so that the timing at which the transfer paper reaches the secondary transfer portion coincides with the timing at which the transfer paper reaches the secondary transfer portion (that is, drive control of the transfer paper transport motor 23 and the belt drive motor 22).
[0037]
In this manner, the transfer speed Vp of the transfer paper and the transfer speed Vb of the intermediate transfer belt are obtained by using one detection sensor 25, and these transfer speeds Vp and Vb are set to have a predetermined relationship, that is, Vp = ΓVb, the belt transport speed and the transfer paper transport speed can be controlled at low cost and accurately regardless of the variation in the roller diameter, so that the belt transport speed and the transfer paper transport speed can be controlled stably. Thus, the secondary transfer image can be transferred to transfer paper to form an image. That is, the transfer paper P is detected by using one detection sensor 25, and the position detection pattern formed on the intermediate transfer belt 11 is detected. The belt transfer speed and the transfer paper transfer speed can be controlled at low cost and accurately regardless of the roller diameter variation, so that the secondary transfer image can be stably formed on the transfer paper. The image can be formed by transferring.
[0038]
By the way, according to an experiment by the inventor, if the detection sensor 25 is arranged within 20 mm from the intermediate transfer belt 11 below the transfer paper transport path and upstream of the secondary transfer section (secondary transfer roller), the intermediate transfer It has been found that the position detection pattern formed on the belt 11 can be detected favorably.
[0039]
In the above-described example, the image forming apparatus using the intermediate transfer belt as the intermediate transfer body has been described. However, the image forming apparatus using the intermediate transfer drum as the intermediate transfer body can be similarly applied.
[0040]
【The invention's effect】
As described above, according to the present invention, the transfer sheet is detected by one detection sensor and the transfer sheet detection signal is sent, and the position detection pattern formed on the intermediate transfer body when the transfer sheet is not present is detected. And sends a pattern detection signal to adjust the variation between the intermediate transfer body and the transfer paper in accordance with the transfer paper detection signal and the pattern detection signal. The transferred image can be secondarily transferred to transfer paper.
[0041]
Further, in the present invention, the transfer speed of the transfer paper is determined as the calculated transfer paper transport speed according to the transfer paper detection signal, and the transport speed of the intermediate transfer body is determined as the calculated intermediate transfer member transport speed according to the pattern detection signal. Thus, there is an effect that the transfer speed of the transfer paper and the transfer speed of the intermediate transfer body can be easily and easily obtained with a simple configuration.
[0042]
In addition, the driving of the intermediate transfer member and the transfer of the transfer sheet are adjusted in accordance with the calculated transfer sheet transfer speed and the calculated intermediate transfer member transfer speed obtained as described above. There is an effect that the transfer image can be secondarily transferred to transfer paper.
[0043]
In the present invention, the timing at which the primary transfer image reaches the secondary transfer position and the timing at which the transfer paper reaches the secondary transfer position are set such that the calculated transfer paper transport speed and the calculated intermediate transfer body transport speed have a predetermined relationship. Since the control is performed, even if the transfer speed of the transfer sheet and the transfer speed of the intermediate transfer member vary, there is an effect that the primary transfer image can be secondarily transferred to the transfer sheet with high accuracy.
[0044]
According to the present invention, the calculated transfer paper transport speed is obtained according to the time when the leading edge of the transfer paper is detected and the time when the trailing edge of the transfer paper is detected, and the time when the leading edge of the position detection pattern is detected and the trailing edge of the position detection pattern are determined. Since the calculated intermediate transfer body transport speed is obtained in accordance with the time at which is detected, there is an effect that the transport speed of the transfer paper and the transport speed of the intermediate transfer body can be easily controlled.
[0045]
Further, in the present invention, the intermediate transfer belt is used as an intermediate transfer member, the intermediate transfer belt is suspended in an inverted triangular shape by at least three suspension rollers, and the position of the suspension roller located at the lowermost side of the three rollers is determined. Is set as the secondary transfer position, there is an effect that the position detection pattern on the transfer paper and the intermediate transfer belt can be accurately detected by one detection sensor.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of an image forming apparatus according to the present invention in a transfer paper detection state.
FIG. 2 is a diagram illustrating an example of an image forming apparatus according to the present invention in a state where an intermediate transfer belt is detected.
FIG. 3 is a diagram illustrating an example of a detection sensor used in the image forming apparatus according to the present invention, together with transfer paper and an intermediate transfer belt.
[Explanation of symbols]
11 Intermediate transfer belt 12-15 Developing units 16a-16d Primary transfer roller 17 Secondary transfer roller 18 Backup roller (secondary transfer opposing roller)
19 Belt transport roller (drive roller)
Reference Signs List 20 tension roller 21 transfer paper transport roller 22 belt drive motor 23 transfer paper transport motor 24 drive controller 25 detection sensor

Claims (9)

An image carrier on which a toner image is formed in accordance with image data; and an intermediate transfer member, which is driven and controlled in a predetermined direction and transfers the toner image from the image carrier as a primary transfer image at a primary transfer position. Transfer means for transferring the primary transfer image from the intermediate transfer body to a transfer paper as a secondary transfer image at a secondary transfer position located downstream of the primary transfer position, wherein the transfer paper is In an image forming apparatus that performs image formation while being transported to a secondary transfer position,
A detection sensor for detecting the transfer paper and transmitting a transfer paper detection signal, and detecting a position detection pattern formed on the intermediate transfer body when the transfer paper is not present, and transmitting a pattern detection signal;
An image forming apparatus comprising: an adjusting unit that adjusts a variation between the intermediate transfer body and the transfer sheet according to the transfer sheet detection signal and the pattern detection signal. An image carrier on which a toner image is formed in accordance with image data; and an intermediate transfer member, which is driven and controlled in a predetermined direction and transfers the toner image from the image carrier as a primary transfer image at a primary transfer position. Transfer means for transferring the primary transfer image from the intermediate transfer body to a transfer paper as a secondary transfer image at a secondary transfer position located downstream of the primary transfer position, wherein the transfer paper is In an image forming apparatus that performs image formation while being transported to a secondary transfer position,
A detection sensor for detecting the transfer paper and transmitting a transfer paper detection signal, and detecting a position detection pattern formed on the intermediate transfer body when the transfer paper is not present, and transmitting a pattern detection signal;
Speed calculating means for calculating the transport speed of the transfer paper as the calculated transfer paper transport speed in accordance with the transfer paper detection signal and calculating the transport speed of the intermediate transfer body as the calculated intermediate transfer body transport speed in accordance with the pattern detection signal; An image forming apparatus comprising: The transfer paper is located below the intermediate transfer body,
The image forming apparatus according to claim 2, wherein the detection sensor is disposed below a conveyance path through which the transfer paper passes. The image forming apparatus according to claim 2, further comprising a control unit configured to adjust driving of the intermediate transfer member and conveyance of the transfer sheet according to the calculated transfer sheet transfer speed and the calculated intermediate transfer member transfer speed. . The transfer paper is located below the intermediate transfer body,
The detection sensor is disposed below the transfer path through which the transfer paper passes,
The image forming apparatus according to claim 2, further comprising a control unit configured to adjust driving of the intermediate transfer member and conveyance of the transfer sheet according to the calculated transfer sheet transfer speed and the calculated intermediate transfer member transfer speed. . The control means controls the timing at which the primary transfer image reaches the secondary transfer position so that the calculated transfer paper transport speed and the calculated intermediate transfer body transport speed have a predetermined relationship. 6. The image forming apparatus according to claim 4, wherein a timing at which the image forming apparatus reaches the next transfer position is controlled. The detection sensor has a light emitting unit and a light receiving unit,
It is determined whether the reflected light is the light reflected on the intermediate transfer member or the light reflected on the transfer paper according to the received light amount distribution of the reflected light received by the light receiving unit, and the reflected light is reflected on the transfer paper. When the light is light, the reflected light is recognized as the transfer paper detection signal, and when the reflected light is light reflected by the intermediate transfer body, a determination unit that recognizes the reflected light as the pattern detection signal is provided. The image forming apparatus according to claim 2, wherein: The speed calculating means obtains the calculated transfer paper transport speed according to the time at which the leading edge of the transfer paper is detected and the time at which the trailing edge of the transfer paper is detected, and the time at which the leading edge of the position detection pattern is detected. The image forming apparatus according to claim 2, wherein the calculated intermediate transfer body transport speed is determined according to a time at which a rear end of the position detection pattern is detected. The intermediate transfer member is an intermediate transfer belt, and the intermediate transfer belt is suspended in an inverted triangular shape by at least three suspension rollers. The image forming apparatus according to claim 2, wherein the image forming apparatus is a next transfer position.

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