JP4893610B2 - Recording material transport apparatus and image forming apparatus using the same - Google Patents

Description

  The present invention relates to a recording material conveying apparatus and an image forming apparatus using the same.

In general, when performing various processes in the image forming apparatus, a wide variety of controls are simultaneously performed by a single CPU. In this case, all the controls are not necessarily processed at the target timing, and may be processed with a delay from the target timing. Therefore, an image defect is generated or a jam is caused.
This is likely to occur, for example, in a case where a lot of processing more than expected is concentrated on a CPU with low processing specifications, or in a color image forming apparatus with complicated control.

  On the other hand, in the control of various conveyance timings during conveyance of the recording material, if an actual variation occurs due to a load or the like, the variation (conveyance delay or the like) is specifically detected by a sensor and the arrival time to a predetermined position is adjusted. Such a method is known (see, for example, Patent Document 1). That is, in such a system, the actual position of the recording material being conveyed is detected by a sensor, and processing is performed so that the difference is compensated based on the detection result.

JP 2005-31020 A (Best Mode for Carrying Out the Invention, FIG. 4)

  The technical problem of the present invention is that when two drive state changes with different operation times are performed on the same recording material in the recording material conveying member, the difference between the operation timing of the predetermined drive state change and the actual execution timing is changed. Even if there is, there is to ensure good recording material transportability.

That is, the invention includes a recording material transport member the recording material to convey the recording material and the recording material conveying path is provided for the recording material conveying path to be conveyed, the recording material conveying member according to the present claim 1 in Upon conveying the recording material, and driving means for driving the recording material transporting member so as to provide a certain driving state change and drive state changes that occur following the specific driving state change to the recording material conveying member, wherein A detection unit that detects a recording material that is provided in the recording material conveyance path and passes through the recording material conveyance path; and a drive control unit that controls the driving unit. a specific timing determining means for determining the operation timing to decelerate the constant speed of the recording material conveying member as a specific drive state changes on the basis of the detection result, the dynamic determined by the particular timing determining means Discriminating means for discriminating the difference between the actual operation timing delayed from the timing and the operation timing, the calculated and the conveyed on the conveying amount of the recording material is excessively transported on the basis of the difference that has been determined by the determining means And a next timing determining means for determining an operation timing for stopping the recording material conveying member as a drive state change that occurs next so that the amount is offset .

According to a second aspect of the present invention, there is provided a recording material conveyance member that is provided for a recording material conveyance path through which a recording material is conveyed and conveys the recording material in the recording material conveyance path, and the recording material conveyance member Driving means for driving the recording material conveying member so as to give a specific driving state change to the recording material conveying member and a driving state change that occurs next to the specific driving state change, and the recording material conveying A detection means for detecting a recording material provided for the path and passing through the recording material conveyance path; and a drive control means for controlling the drive means, wherein the drive control means is configured to detect a detection result of the detection means. A specific timing determining means for determining an operation timing for stopping the recording material conveying member at a constant speed as a specific drive state change, and an operation timing determined by the specific timing determining means; A discriminating unit that discriminates a difference from an actual operation timing delayed from the operation timing, and calculates a transport amount in which the recording material is transported excessively based on the difference discriminated by the discriminating unit, and the transport amount is It is a recording material conveying apparatus comprising: a next timing determining means for determining an operation timing for starting the recording material conveying member as a drive state change that occurs next so as to be offset.
According to a third aspect of the present invention, there is provided the recording material conveying apparatus according to the first aspect, wherein the recording material conveying member is a return conveying member that returns and conveys the recording material having an image formed on one side thereof in an inverted state. It is a transport device.
According to a fourth aspect of the invention, there is provided the recording material conveying apparatus according to the second aspect, wherein the next timing determining means is restarted at a slower speed than a constant speed recording material conveying member before stopping.
The invention according to claim 5 is the recording material transport apparatus according to claim 2, wherein the next timing determining means is restarted at the same speed as the constant speed recording material transport member before stopping.
According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising: an image forming unit that forms an image on a recording material; and the recording material conveying device according to any one of claims 1 to 5 that conveys the recording material to the image forming unit. Device.

According to the first or second aspect of the invention, when the recording material is transported by the recording material transport member, the operation timing of the preceding driving state change and the actual execution are given when two driving state changes having different operation times are given. Even if there is a discrepancy with the timing, the difference is determined without using a dedicated detection means, and the operation timing of the next driving state change is determined based on the difference, so that good recording material transportability is achieved. It will be possible to secure.
According to the third aspect of the present invention, the actual conveyance amount of the recording material in the return conveyance path can be made constant and a predetermined loop amount can be provided, as compared with the case where this configuration is not provided. Easy to apply to.
According to the fourth aspect of the present invention, the recording material can be delivered between the apparatuses and the like better than when the present configuration is not provided.
According to the fifth aspect of the present invention, it is possible to make the conveyance amount of the recording material uniform as compared with the case where the present configuration is not provided, and to ensure an appropriate loop amount when performing loop control, for example. Become.
According to the sixth aspect of the present invention, when the same recording material is conveyed by the recording material conveying member, when the two driving state changes having different operation times are given, the operation timing of the preceding driving state change and the actual execution are performed. Even if there is a discrepancy with the timing, the discriminating of this difference without using a dedicated detection means, and determining the operation timing of the next drive state change based on the difference ensures good recording material transportability It is possible to easily provide an image forming apparatus that can do this.

First, an outline of an embodiment model to which the present invention is applied will be described.
Outline of Embodiment Model FIG. 1 shows an outline of a recording material conveying apparatus according to an embodiment model embodying the present invention. Here, one of the representative model of the recording material conveying apparatus, FIG. 1 (a), a provided for the recording material conveyance path 2 that the recording material 1 is conveyed and the recording material conveying path 2 a recording material conveying member 3 for conveying the recording material 1 in, when conveying the recording material 1 in the recording material conveying member 3, recording material transport to member 3 specific driving state change and the specific driving state change Drive means 4 for driving the recording material conveyance member 3 so as to perform the next drive state change, and detection for detecting the recording material 1 provided for the recording material conveyance path 2 and passing through the recording material conveyance path 2 Means 5 and drive control means 6 for controlling the drive means 4, and the drive control means 6 decelerates the constant speed recording material conveying member 3 as a specific drive state change based on the detection result of the detection means 5 . Specific timing determining means for determining operation timing When a determination means 8 for determining the difference between the actual operation timing delayed from the operation timing and the operation timing determined by the particular timing determining unit 7, the recording on the basis of the difference that has been determined by the determination means 8 A next timing determining means 9 for calculating an amount of conveyance of the extra material 1 and determining an operation timing for stopping the recording material conveying member 3 as a driving state change that occurs next so that the amount of conveyance is offset ; It has. Note that (b) shows each timing.

  Here, “change in driving state” means that the driving state of the recording material conveyance member 3 is changed, such as stop, activation, acceleration, deceleration, and the like of the recording material conveyance member 3, thereby recording. The conveyance state of the material 1 itself changes. Further, “determining the operation timing of the next drive state change that occurs based on the difference” means that the recording material 1 transported by the recording material transport member 3 is transported to a predetermined position by a specific drive state change. This means that the operation timing of the next drive state change that occurs is determined in consideration of the difference from the power position, and is intended to convey the recording material 1 to a desired position by the next drive state change that occurs. Is.

Further, the number and shape of the recording material conveying member 3 are not limited as long as the recording material 1 can be conveyed. For example, the recording material conveying member 3 may be a pair of roll-shaped members or a plurality of pairs of roll-shaped members. In the case of a plurality of configurations, the arrangement positions may be distributed and arranged. Moreover, it is not restricted to a roll-shaped member, A belt-shaped member may be used.
On the other hand, as the driving means 4, it is sufficient that the recording material conveying member 3 can change the conveying state of the recording material 1. Typical examples include a motor and a clutch.
Further, the arrangement position of the detection means 5 is not particularly limited, and may be a position where the passing information of the recording material 1 can be detected, and the upstream side or the downstream side of the recording material conveyance path 3 with respect to the recording material conveyance path 2. Alternatively, in an aspect in which a plurality of recording material conveying members 3 are provided, they may be provided for the recording material conveying path 2 inside them. The recording material passage information by the detection means 5 may be such that the recording material 1 being passed is detected by the detection means 5 or the recording material 1 in a stopped state may be detected. In short, it is sufficient that the passage information of the recording material 1 can be acquired.

  In the present embodiment model, the drive control means 6 determines the operation timing of the specific drive state change of the recording material transport member 3 based on the detection result of the detection means 5, and the determined operation timing and later than that. It is characterized in that the difference from the actual operation timing made is determined, and the operation timing of the next drive state change for the same recording material 1 is determined based on this difference. Therefore, it can be applied to various places in recording material conveyance.

Then, as a specific recording material transport apparatus to which the present embodiment model is applied, the following modes are exemplified. That is, the first aspect, the conveyance member return the recording material conveying member 3 conveyed back in a state where the image on one side by inverting the already formed recording material, reduction drive control means 6, the return conveying members A specific timing determining means 7 to be stopped and a next timing determining means 9 for stopping the decelerated return conveying member, or as a second aspect, the drive control means 6 conveys the recording material at a predetermined speed. A specific timing determining means 7 for stopping the member 3 and a next timing determining means 9 for restarting the stopped recording material conveying member 3 at a speed different from the predetermined speed, or as a third aspect The drive control unit 6 restarts the stopped recording material conveying member 3 at the predetermined speed and the specific timing determining unit 7 for stopping the recording material conveying member 3 at the predetermined speed. Such aspects and a next timing determination means 9 and the like.

  The model of the present embodiment is not limited to such a recording material conveying device, and an image forming unit that forms an image on the recording material 1 and a recording material conveying device that conveys the recording material 1 to the image forming unit. In this case, the recording material conveyance device may be provided as the recording material conveyance device.

Hereinafter, the present invention will be described in more detail based on embodiments shown in the accompanying drawings.
Embodiment FIG. 2 shows an embodiment of an image forming apparatus to which the recording material conveying apparatus of the model of the present embodiment is applied. In the figure, the image forming apparatus according to the present embodiment includes an image forming apparatus 10 having an image forming unit 20 that forms an image on a recording material, and an image forming apparatus 10 side below the image forming apparatus 10. And a recording material supply device 40 for storing the recording material supplied to the recording medium.

  The image forming unit 20 includes an intermediate transfer belt 21 that is stretched between a plurality of stretching rolls 22 to 24 and that rotates in the direction of the arrow in the drawing at the approximate center of the image forming apparatus 10. Four image forming units 30 (30a to 30d) arranged in parallel along the rotation direction are arranged. The image forming unit 30 forms, for example, yellow (Y color), magenta (M color), cyan (C color), and black (K color) toner images, and is formed by the image forming units 30a to 30d. The respective color toner images are sequentially transferred onto the intermediate transfer belt 21 to form a multiplexed multi-color toner image on the intermediate transfer belt 21.

Further, a transfer roll 25 for transferring the toner image on the intermediate transfer belt 21 onto a recording material supplied from the recording material supply device 40 is provided at a position facing the tension roll 23 across the intermediate transfer belt 21. By applying a predetermined transfer bias between the transfer roll 25 and the stretching roll 23, the multicolor toner image on the intermediate transfer belt 21 is transferred onto the recording material.
A fixing device 26 for fixing the multicolor toner image transferred on the recording material is provided above the transfer roll 25. Note that reference numeral 70 in the figure denotes a control device that performs various controls.

  On the other hand, the recording material supply device 40 includes, for example, three stages of recording material storage containers 41 (41 a to 41 c) so that recording materials of three different sizes can be supplied, and the recording materials of the respective recording material storage containers 41. Near the downstream side in the transport direction, at least during the supply of the recording material, a supply roll 42 that contacts the recording material on the uppermost surface in the recording material storage container 41 and transports the recording material downstream, and this supply roll 42 A separating roll 43 is provided which performs a rolling action on the recording material conveyed from the supply roll 42 on the downstream side of the recording material to convey only one recording material.

Here, a recording material conveyance system in the image forming apparatus of the present embodiment will be described.
In the present embodiment, the recording material supply device 40 is provided with a main conveyance path 51 extending upward for guiding the recording material supplied from each recording material container 41 to the image forming device 10 side. The path 51 is formed so as to extend upward in the image forming apparatus 10 as it is.
In the main conveyance path 51 in the recording material supply device 40, a supply sensor 52 for detecting the recording material that has passed through the separation roll 43 from each recording material container 41 is provided in the vicinity of the downstream side of the separation roll 43. On the other hand, a conveyance sensor 54 that detects the passage state of the recording material conveyed by the conveyance roll 53 is provided in the vicinity of the downstream side of the conveyance roll 53 provided on the downstream side of the supply sensor 52.

The main conveyance path 51 in the image forming apparatus 10 is provided with a registration roll 55 that positions the recording material conveyed from the recording material supply device 40 side and conveys the recording material downstream at a predetermined timing. A registration sensor 56 that detects the conveyance state of the recording material to the registration roll 55 is provided in the vicinity of the upstream side of 55.
Further, a transfer roll 25 is disposed on the downstream side of the registration roll 55 in the main transport path 51, and is provided near the end opening of the image forming apparatus 10 via a fixing device 26 on the downstream side of the transfer roll 25. A discharge roll 57 is provided.

  Therefore, only one sheet of the recording material supplied from each recording material storage container 41 by the supply roll 42 is transported into the main transport path 51 by the separating roll 43 and reaches the registration roll 55. The recording material positioned by the resist roll 55 is conveyed at a predetermined timing, and the multicolor toner multiplexed on the intermediate transfer belt 21 is transferred at a transfer portion (a portion where the transfer roll 25 and the intermediate transfer belt 21 face each other). The image is transferred. The recording material that has been transferred is fixed as it is by the fixing device 26, and the recording material that has been fixed is discharged from the end opening of the image forming apparatus 10 by the discharge roll 57 to the upper surface of the apparatus housing of the image forming apparatus 10. It is discharged to a recording material discharge receiver 11 provided on the side.

  Further, in the present embodiment, a recording medium having an image formed on one side thereof is reversed and conveyed from the middle of the main conveyance path 51, and a return conveyance path 61 is provided on the remaining one side for forming a new image. It has been. That is, the recording material is returned and conveyed from the main conveyance path 51 to the return conveyance path 61 as it is by performing a reverse operation of the discharge roll 57 under the condition that the vicinity of the rear end of the recording material is sandwiched between the ejection rolls 57. It becomes like this. The return transport path 61 is provided with return transport rolls 62 and 63 for returning and transporting the recording material, and the recording material passes through the return transport path 61 between the return transport rolls 62 and 63. A return sensor 64 is provided for detecting. The recording material transported back through the return transport path 61 by the return transport rollers 62 and 63 is positioned by the registration roller 55 and then transported to the transfer site at a predetermined timing. Image formation is performed.

Further, in the present embodiment, various controls including the recording material conveyance control in the main conveyance path 51 and the return conveyance path 61 can be realized by the control device 70. Therefore, the control device 70 controls the entire image forming apparatus. Here, a part of the recording material conveyance control system will be described.
The transport control system in the control device 70 of the present embodiment is as shown in FIG. In other words, based on the recording material passage information from various sensors, a specific timing determining unit 71 that determines the operation timing of a predetermined driving state change (corresponding to a specific driving state change) for the recording material for the recording material. A difference determination unit 72 for determining a difference between the operation timing determined by the specific timing determination unit 71 and a timing at which a predetermined drive state change (specific drive state change) is actually made by the transport roll; A next timing determining unit 73 that determines the operation timing of the next driving state change based on this difference is provided.
Then, for example, a drive motor, which is a driving means for various transport rolls, is controlled at the operation timing determined by the next timing determination unit 73.

Next, the recording material conveyance state in various recording material conveyance sites of the present embodiment will be described.
FIG. 4 is a partially enlarged view of the return transport path 61, in which the return transport roll 63, the registration roll 55, the return sensor 64, and the registration sensor 56 are arranged. The return transport roll 63 and the registration roll 55 are provided with drive motors 81 and 82 for driving them, respectively. The drive motors 81 and 82 are controlled by a control device based on signals from the return sensor 64 and the registration sensor 56. The drive control is performed by 70.
In particular, here, in order to correct the skew of the recording material fed back, the leading end of the recording material is abutted against the resist roll 55 to give a predetermined amount of bending deformation (loop amount).

Therefore, the control flow in the control device 70 is as shown in FIG.
First, it is determined whether or not the recording material has passed through the detection signal from the return sensor 64. After a predetermined time has elapsed, the return transport roll 63 (specifically, the drive motor 81 of the return transport roll 63) is specified. The timing for deceleration as the driving state change is determined (steps S1 to S3). Next, it is determined whether or not the return conveyance roll 63 is actually decelerated, and the difference is determined by counting the time until the decelerating roll 63 is actually decelerated (steps S4 and S5). Then, when the return transport roll 63 is actually decelerated, the distance (corresponding to time × speed) at the speed of the return transport roll 63 before deceleration is calculated from the time (difference) counted in step S5. Next, the time required to travel equidistant at the speed at which the return transport roll 63 decelerates is calculated, and the calculated time (Δt) is stored (steps S6 and S7).
Next, a time (T−Δt) obtained by subtracting the stored time Δt from the time T (reference time) from the time when the recording material passes the return sensor 64 during the normal operation to the time when the return conveyance roll 63 is stopped. When it is determined that it has elapsed, the return conveying roll 63 is stopped as the next driving state change (steps S8 and S9).

Here, the operation in such a control flow will be described.
FIG. 6 is a schematic diagram showing how the speed of the return transport roll 63 changes. The return transport roll 63 that transported the recording material at the initial speed V1 is decelerated to the speed V2 on the way and finally stopped. It represents the situation. The solid line indicates normal control. After the recording material is detected by the return sensor 64, the recording material is decelerated (V1 → V2) at a predetermined timing, and the decelerated return transport roll 63 stops after the reference time T. .
At this time, assuming a case where the skewed recording material is transported, the recording material is transported back in the transport path 61 toward the registration roll 55, and gradually when one end of the recording material hits the registration roll 55. Bends. This bending deformation is performed to some extent, a predetermined amount of bending deformation (loop amount) is formed, and the feeding of the recording material by the return conveying roll 63 is stopped, so that a reaction force that is deformed by bending acts on the recording material. Then, the leading ends of the recording materials are aligned in the axial direction of the registration roll 55. Therefore, when the recording material is conveyed by the registration roll 55, the recording material is conveyed in a state where the skew is corrected.

On the other hand, in such control, as indicated by a broken line in the figure, it is assumed that actual deceleration (specific drive state change) is executed at a timing delayed by Δt ′ with respect to the deceleration timing from the control device 70. Then, the recording material transported by the return transport roll 63 is transported excessively. For this reason, if the conveying roll 63 is stopped at the reference time T as it is, the recording material is conveyed more than usual, and the recording material is subjected to deformation exceeding a predetermined bending deformation amount. There is a possibility that defects such as creases and wrinkles may occur and skew correction is not sufficiently performed.
Therefore, in the present embodiment, Δt is calculated so that the return conveyance roll 63 is stopped earlier by the amount that the recording material is excessively conveyed, and the return conveyance roll 63 is stopped at a timing earlier by Δt than the reference time T ( Next, the drive state changes that occur). At this time, Δt is obtained so that the areas of the two hatched portions in the figure are equal.

Next, as shown in FIG. 4, the control motor 70 starts the drive motor 82 in accordance with the image formation timing in the image forming unit 20, so that the registration roll 55 rotates and the skew correction is performed. The recording material is conveyed to the transfer site.
Therefore, by controlling in this way, when image formation is performed on the opposite surface of the recording material on which image formation has been performed on one side, skew in the recording material conveyed through the return conveyance path 61 is sufficiently corrected. As a result, there is no occurrence of folding or wrinkling on the recording material, and a good image is formed. Although the registration sensor 56 is shown here, it is needless to say that by performing such control, good return conveyance is performed without providing the registration sensor 56.

  Next, FIG. 7 is a partially enlarged view of a portion where the recording material is supplied from the recording material storage container 41 to the main transport path 51 in the recording material supply apparatus 40 according to the present embodiment. Here, the conveyance of the recording material to the registration roll 55 of the image forming apparatus 10 is temporarily stopped and then resumed so that the recording material reaches the registration roll 55 at a predetermined time. Therefore, the driving roll 83 (including the supply roll 42) is connected to the drive motor 83 via the clutch 84, while the transport roll 53 is connected to the drive motor 83 via the clutch 85. . Further, a control device 70 is provided so as to control the clutches 84 and 85 and the drive motor 83 based on signals from the supply sensor 52 and the conveyance sensor 54.

A control flow in the control device 70 in this case is as shown in FIG.
First, it is determined whether or not the recording material has passed through the detection signal from the supply sensor 52, and the timing for turning off the clutches 84 and 85 is determined in order to temporarily stop the recording material after a predetermined time has elapsed. (Steps S11 to S13). Next, it is determined whether or not the clutches 84 and 85 are actually turned off, and when not executed, the time until the actual turning off is counted (steps S14 and S15). When the clutch 85 is turned off, the time (Δt) counted in step S15 is stored as a difference (step S16).
Next, it is confirmed whether or not there is a reference signal (supply start signal or the like) corresponding to image formation in the image forming unit 20. If there is a reference signal, a predetermined time elapses, and further, after Δt elapses, the clutch 84. , 85 are turned on to resume the conveyance of the recording material once stopped (steps S17 to S19).

Next, the operation in such a control flow will be described.
FIG. 9 is a schematic diagram showing how the clutches 84 and 85 operate. The clutch 84 and 85 that were initially turned on are turned off at a predetermined timing and turned on after the reference signal. It is a thing. A solid line indicates normal control. After the clutch 85 is turned on, the recording material is detected by the supply sensor 52 and then turned off at a predetermined timing. After the reference signal from the image forming unit 20 is turned on after a predetermined time Tt. Become so.

At this time, as indicated by a broken line in the figure, it is assumed that the actual OFF is executed at a timing delayed by Δt with respect to the operation timing of the clutch 85 from the control device 70 (specific drive state change). The interval between the recording material and the resist roll 55 is narrowed by conveying more recording material conveyed by the rolling roller 43 and the conveying roller 53 than expected. Therefore, if the clutches 84 and 85 are turned on based on the reference signal as they are (the drive state change that occurs next), the recording material comes into contact with the registration roll 55 quickly, and the amount of deflection (loop amount) is appropriate. May become different, and there is a risk that predetermined skew correction will not be performed, and defects such as creases and wrinkles in the recording material may occur.
Therefore, in the present embodiment, the recording material arrival timing with respect to the registration roll 55 is matched by delaying the timing at which the conveyance is resumed by the amount that the stop of the conveyance of the recording material is delayed. A predetermined loop amount can be formed, skew correction can be satisfactorily performed, and defects such as folds and wrinkles can be prevented from occurring.

  Furthermore, by performing control in this way, the registration sensor 56 (see FIG. 2) can be made unnecessary. Although an example in which the ON / OFF control of the clutches 84 and 85 is shown here, it goes without saying that the drive motor 83 may be controlled.

FIG. 10 is a partially enlarged view of the main conveyance path 51 between the recording material supply apparatus 40 and the image forming apparatus 10 as a modification of the present embodiment. Here, a conveyance roll 53 and a conveyance sensor 54 provided on the recording material supply apparatus 40 side, and a registration roll 55 provided on the image forming apparatus 10 side are respectively included in the conveyance roll 53 and the registration roll 55. Drive motors 86 and 87 are provided. In this example, the control device 70 controls the drive motors 82 and 83 based on a signal from the conveyance sensor 54 and the like.
In particular, here, the recording material conveyed from the recording material supply device 40 is temporarily stopped by temporarily stopping the conveying roller 53 that conveys the recording material at the initial speed, and decelerating and restarting the conveying roller 53 after a predetermined time has elapsed. The amount of loop in the resist roll 55 is made appropriate.

Therefore, the control flow in the control device 70 is as shown in FIG.
First, it is determined whether or not the recording material has passed through the detection signal from the conveyance sensor 54, and the operation timing for stopping the conveyance roll 53 after a predetermined time has elapsed (steps S21 to S23). Next, it is determined whether or not the transport roll 53 is actually stopped, and the time until the stop is specifically executed is counted (steps S24 and S25). Then, when the stop is executed, the distance (corresponding to time × speed) at the speed of the transport roll 53 before the stop is calculated from the time counted in step S25, and then the distance at the restart is equal. Is calculated, and the calculated time (Δt) is stored (steps S26 and S27).
Next, it is confirmed whether or not there is a reference signal corresponding to image formation in the image forming unit 20. If there is a reference signal, a predetermined time elapses, and further, after Δt elapses, the transport roll 53 is restarted ( Steps S28 to S30).

Next, the operation in such a control flow will be described.
FIG. 12 is a schematic diagram showing how the speed of the transport roll 53 changes. The transport roll 53, which initially transported the recording material at the speed V3, once stops and then restarts at the speed V4. It is a thing. A solid line indicates normal control, and after the recording material is detected by the conveyance sensor 54, the recording material stops at a predetermined timing, and restarts after a predetermined time Tt after the reference signal.

At this time, as indicated by a broken line in the figure, a state where the actual stop is made at a timing delayed by Δt ′ with respect to the operation timing from the control device 70 to stop the transport roll 53 (specific drive state change). Assuming that the recording material transported by the transport roll 53 is transported excessively to the downstream side of the transport roll 53 accordingly. For this reason, when restarting after the predetermined time Tt from the reference signal (next driving state change), the recording material reaches the downstream side earlier than usual. For this reason, the time of hitting the registration roll 55 is shortened, and there is a possibility that an excessive load is applied to the recording material, or even if an attempt is made to correct the skew feeding, it is not sufficient.
Therefore, in the present embodiment, the recording material arrival time on the downstream side is adjusted by delaying the restart time by Δt so as to delay the restart of the transport roll 53 by the amount that the recording material has been transported excessively. I have to. Note that Δt is obtained so that the areas of the two hatched portions in the figure are equal.

Here, the recording material conveyance process between the recording material supply device 40 and the registration roll 55 is shown. However, for example, by performing such a conveyance process between the apparatuses, the recording material conveyance between the apparatuses is performed. Can also be carried out satisfactorily.
As described above, in the present embodiment, since the actual difference is detected by the control device 70, a dedicated sensor for detecting the recording material conveyance state is not used, so the number of sensors in the device is reduced. It is also possible to do. In addition, the performance of the CPU used in the control device 70 can be suppressed to a certain extent.
Further, such control is not limited to the above-described mode, and can be applied to the same conveyance processing operation in the recording material conveyance path.

  In this embodiment, an apparatus for forming a color image is shown as an image forming apparatus. However, the present invention is not limited to this, and the present invention may be applied to an apparatus for forming a monochrome image. In this embodiment, the intermediate transfer belt 21 is used. However, a system in which the toner image from the image forming unit 30 is directly transferred onto the recording material may be adopted, and an image forming system may be used. For example, an ink jet drawing method may be adopted without being limited to the electrophotographic method.

(A) (b) is explanatory drawing which shows the outline | summary of the recording material conveying apparatus based on this Embodiment model. 1 is an explanatory diagram showing an overview of an image forming apparatus according to an embodiment. It is a block diagram which shows the conveyance control system in the control apparatus of embodiment. It is the elements on larger scale of a return conveyance path. It is a flowchart which shows the control flow at the time of return conveyance. It is a schematic diagram which shows the speed change of the conveyance roll in a return conveyance path. It is a partial enlarged view of a recording material supply site. It is a flowchart which shows the control flow at the time of recording material supply. It is a schematic diagram showing the operation of the clutch of the recording material supply site. It is the elements on larger scale of the main conveyance path as a form of modification. It is a flowchart which shows the control flow in a main conveyance path. It is a schematic diagram which shows the speed change of the conveyance roll in a main conveyance path.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Recording material, 2 ... Recording material conveyance path, 3 ... Recording material conveyance member, 4 ... Drive means, 5 ... Detection means, 6 ... Drive control means, 7 ... Specific timing determination means, 8 ... Discrimination means, 9 ... Next Timing determination means

Claims (6)

A recording material conveying member that is provided for a recording material conveying path through which the recording material is conveyed and conveys the recording material in the recording material conveying path;
When the recording material is conveyed by the recording material conveying member, the recording material conveying member is driven so as to give a specific driving state change to the recording material conveying member and a driving state change that occurs next to the specific driving state change. Driving means;
Detection means provided for the recording material conveyance path and detecting a recording material passing through the recording material conveyance path;
Drive control means for controlling the drive means,
The drive control means includes
Specific timing determining means for determining an operation timing for decelerating a constant speed recording material conveying member as a specific drive state change based on a detection result of the detecting means;
Discriminating means for discriminating a difference between the operation timing determined by the specific timing determining means and the actual operation timing delayed from the operation timing;
An operation for calculating a transport amount in which the recording material is transported excessively based on the difference determined by the determination means and stopping the recording material transport member as a driving state change that occurs next so that the transport amount is offset. A recording material conveying apparatus comprising: next timing determining means for determining timing. A recording material conveying member that is provided for a recording material conveying path through which the recording material is conveyed and conveys the recording material in the recording material conveying path;
When the recording material is conveyed by the recording material conveying member, the recording material conveying member is driven so as to give a specific driving state change to the recording material conveying member and a driving state change that occurs next to the specific driving state change. Driving means;
Detection means provided for the recording material conveyance path and detecting a recording material passing through the recording material conveyance path;
Drive control means for controlling the drive means,
The drive control means includes
Specific timing determining means for determining an operation timing for stopping the constant speed recording material conveying member as a specific drive state change based on the detection result of the detecting means;
Discriminating means for discriminating a difference between the operation timing determined by the specific timing determining means and the actual operation timing delayed from the operation timing;
An operation of calculating a transport amount in which the recording material is transported excessively based on the difference determined by the determination means and starting the recording material transport member as a driving state change that occurs next so that the transport amount is offset A recording material conveying apparatus comprising: next timing determining means for determining timing. The recording material conveying apparatus according to claim 1,
2. A recording material conveying apparatus according to claim 1, wherein the recording material conveying member is a return conveying member that returns and conveys the recording material having an image formed on one side thereof in an inverted state. The recording material conveying apparatus according to claim 2,
The recording material conveying apparatus, wherein the next timing determining means restarts at a slower speed than a constant speed recording material conveying member before stopping. The recording material conveying apparatus according to claim 2,
The recording material conveying apparatus, wherein the next timing determining means restarts at the same speed as the constant-speed recording material conveying member before stopping. An image forming unit that forms an image on a recording material;
An image forming apparatus, comprising a recording material conveying device according to any one of claims 1 to 5 for conveying the recording material to the image forming unit.

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