JP4306934B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus that performs control operations such as early arrival, detection of delay, correction processing, and the like of sheet conveyance processing in which catch-up control is performed with an upstream conveyance speed faster than a downstream conveyance speed.
[0002]
[Prior art]
Conventionally, as the tendency of downsizing of an image forming apparatus and high speed of image forming increases, it becomes necessary to reduce the paper transport space, reduce the distance between papers, and increase the paper transport speed. It was. However, it is difficult to accurately grasp the position of the paper being transported due to variations in the coupling operation, etc., with the method of controlling the paper transport drive by connecting a clutch or solenoid to a DC motor as a means for driving the paper transport. is there.
[0003]
In recent years, stepping motors that can accurately control the position of paper by managing the number of pulses and their frequency have been used. As a characteristic of the stepping motor, it is desirable to perform acceleration / deceleration over a sufficient time since a large torque is required when the rotational acceleration increases or decreases when the rotation is started or stopped.
[0004]
In any case, it is necessary to increase the conveyance speed in order to increase the speed of the image forming process. However, when considering the toner shape, fixing characteristics, laser emission characteristics, cost, etc., the rotational speed of the photosensitive drum for forming the latent image and the fixing roller for fixing the toner and recording the image data are relatively slow. In addition, it is considered necessary to design an image forming apparatus having a paper conveyance form that conveys paper on the condition that the conveyance speed is high. That is, it is necessary to perform catch-up control such that the conveyance speed is fast in the upstream part of image formation and slow in the downstream part. In the catch-up control, the preceding sheet is conveyed at a low speed. Therefore, it is necessary to arrive at a position where the conveying speed changes in anticipation of a timing at which the following sheet does not collide with the preceding sheet. On the other hand, in order to satisfy productivity, it must not arrive later than a predetermined interval.
[0005]
[Problems to be solved by the invention]
In the catching-up control, at the connecting part of the transport path, which is the difference in transport speed, the downstream paper is not connected to the connecting part because the downstream transport speed is slow and the trailing edge of the preceding paper has not left the connecting part. I will rush. This phenomenon is called early arrival. When it arrives early, the trailing edge of the preceding paper and the leading edge of the succeeding paper cause double feeding, and printing is performed on the overlapping sheets at the time of image formation, so that normal image formation cannot be performed. Also, in the optical detection type sensor that detects ON (paper present) or OFF (paper absent) when the paper passes, the paper does not move even though a predetermined length of paper is being conveyed at a predetermined speed. Due to the multi-feeding, even if the sensor is turned on / off for a predetermined time, a phenomenon that the sensor OFF after the sensor ON does not occur easily occurs. This makes it impossible to accurately grasp and convey the paper position.
[0006]
On the other hand, when the entry of the succeeding paper into the connecting portion of the transport path, which is a difference in transport speed, is very delayed, a phenomenon of delay occurs. In the paper conveyance of the image forming apparatus, in order to satisfy the productivity, the conveyance of the paper is started from the connecting portion of the conveyance path having a different conveyance speed at a predetermined interval. In the case of the delay, the sheet conveyance start time is delayed from a predetermined interval, which greatly affects the productivity. Furthermore, if the delay is further advanced, the following paper will be hit and jammed.
[0007]
When performing catch-up control in paper conveyance, there is a problem that the above-described early arrival and delay must be solved.
[0008]
The present invention has been made in view of the above-described circumstances, and can achieve high productivity at low cost, and in catch-up control, which is paper conveyance control in which position management of the paper to be conveyed is difficult, Prevents double-feeding of subsequent paper, flexibly and accurately corrects problems such as early arrival and delay, and enables long-lasting and reliable paper transport even when used for a long time. An object of the present invention is to provide an image forming apparatus that guarantees the above.
[0009]
[Means for Solving the Problems]
This invention can solve the said subject by providing the following structure.
[0010]
(1) A paper storage unit for storing paper, a paper feed unit for feeding the paper stored in the paper storage unit one by one, and a first transport for transporting the paper fed by the paper feed unit Means, a detecting means for detecting the presence / absence of paper conveyed by the first conveying means, and a speed lower than the conveying speed of the first conveying means, provided downstream of the first conveying means. And a trailing edge of the preceding sheet conveyed prior to the succeeding sheet when the leading edge of the succeeding sheet subsequently conveyed by the detecting means is detected. A time indexing means for determining a time TA until the second transporting means and a time TB until the leading edge of the succeeding paper arrives at the second transporting means, and the time TA calculated by the time indexing means And based on the difference time of the time TB A determination unit that determines whether a leading edge of the succeeding sheet catches up with a trailing edge of the preceding sheet; and the determination unit determines that the leading edge of the succeeding sheet catches up with a trailing edge of the preceding sheet. A conveyance control unit that temporarily stops conveyance of the succeeding sheet by the first conveyance unit so as to delay arrival at the second conveyance unit by a time according to time; Forming equipment.
(2) In the image forming apparatus according to (1), the determination unit determines that the leading edge of the succeeding sheet catches up with the trailing edge of the preceding sheet when the time TA is greater than the time TB. An image forming apparatus.
[0042]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0043]
(Example)
FIG. 1 is a longitudinal side view showing a main configuration of an image forming apparatus according to the present invention.
[0044]
In FIG. 1, this image processing apparatus includes a main body image output unit 10 which is a device for placing and outputting a document image on a recording paper, a main body image input unit 11 which is a device for reading image data from a document, and a main body image input. An automatic document feeder 12 mounted on the top of the unit 11 and a sorter 13 for sorting and ejecting copy sheets discharged from the main body image output unit 10 into a plurality of bins are provided.
[0045]
This image forming apparatus is an example of a digital copying machine, pixelated by a CCD of a main body image input unit 11 which is an apparatus for reading image data from a document, read into the apparatus as image data, and necessary image processing was performed. Thereafter, it is stored in an image memory (not shown). The image data is transferred to the main body image output unit 10, and the image is reproduced and copied onto a recording sheet.
[0046]
The main body image input unit 11 includes a light source 21 that performs scanning while irradiating a document placed on a document table on the upper surface of the input unit. The light source 21 obtains a driving force from an optical system motor (not shown) and reciprocates in the left-right direction on the paper surface of FIG. The light generated from the light source 21 is reflected by the stacked originals to obtain an optical image. The optical image is transmitted to the CCD 26 via the mirrors 22, 23 and 24 and the lens 25. The mirrors 22, 23, and 24 are driven integrally with the light source 21. The CCD 26 is composed of an element that converts light into an electrical signal, and an optical image transmitted by the function of the element is converted into an electrical signal and further converted into a digital signal (image data).
[0047]
The read image data of the original is subjected to various correction processes and image processes desired by the user, and is stored in an image memory (not shown).
[0048]
The main body image output unit 10 reads the image data stored in the image memory, reconverts the digital signal into an analog signal, and further amplifies the output value to an appropriate output value by an exposure control unit (not shown). Converted to a signal. The optical signal propagates through the scanner 28, the lens 29, and the mirror 30 and is irradiated onto the photosensitive drum 114, thereby forming a latent image by static electricity. This latent image forms an image with toner, and is transferred onto the recording paper conveyed through the main body. Further, the toner is fixed on the recording paper by the fixing roller 32, and image data is recorded and sent to the sorter 13.
[0049]
The sorter 13 is a device installed on the left side of the main body image output unit 10 on the paper surface, and performs a process of sorting the recording paper output from the main body image output unit 10 to the discharge tray 33 and discharging it. The paper discharge tray 33 is controlled by the main body control unit (not shown), and the output recording paper is discharged to an arbitrary paper discharge tray 33 instructed by the control unit.
[0050]
The paper feed trays 34 and 35 are located in the lower part of the main body, and can store recording paper to some extent. The control unit conveys the accumulated recording paper from the paper feed trays 34 and 35 and outputs an image. Paper feed deck 36, on paper, in devices installed in the right side of the main picture output unit 10, it is possible to have accumulated large amounts of paper. As with the paper feed trays 34 and 35, the recording paper accumulated by the control unit is conveyed to output an image.
[0051]
A manual feed tray 37 that allows an operator to relatively easily feed a small number of arbitrary types of copy paper is installed on the right side of the main body image output unit 10 on the paper surface. The manual feed tray 37 is also used when special recording paper such as an OHP sheet, cardboard, or postcard size paper is used.
[0052]
Reference numerals 38, 39, 40, 41, and 42 forming the paper feed rollers are paper transport rollers, and each roller plays a role of actually transporting the recording paper when feeding the copy output process. Each paper feed roller is connected to a stepping motor as an independent drive source via a transmission device such as a gear.
[0053]
Reference numeral 113 denotes a sensor, which can determine that the paper is present when the sensor is turned on, and can determine that there is no paper when the sensor is turned off.
[0054]
Here, the rotational speed of the photosensitive drum 114 for forming a latent image controlled by a DC brushless motor and the fixing roller 32 for fixing toner on a recording medium and recording image data is called a process speed. It is difficult to achieve variable control because it depends greatly on the shape and fixing characteristics of the toner, the light emission characteristics of the laser, etc., and the speed is specific to each image forming apparatus. On the other hand, the paper feed roller and the transport roller perform only the operation of feeding and transporting the recording medium. When no paper is sandwiched between the fixing roller 32 and the photosensitive drum 114, the transport is performed. By driving as fast as possible and controlling the distance between papers as short as possible, productivity as an image forming apparatus is improved. This transport control method is called catch-up control.
[0055]
FIG. 2 is an explanatory diagram illustrating a state during normal paper conveyance in the catch-up control. In other words, this represents a state of paper conveyance when the image forming apparatus performs catch-up control and performs normal paper conveyance.
[0056]
In FIG. 2, the horizontal axis represents time, the vertical axis represents distance, and the slope represents transport speed. The connecting portion of the conveyance speed, which is the difference in conveyance speed, is the registration roller 112, and the sheet is conveyed at a conveyance speed V1 that is upstream of the registration roller 112 at a high conveyance speed V1 and at a conveyance speed that is downstream from the registration roller 112 at a conveyance speed V2. . A1 is the leading edge of the preceding paper, A2 is the trailing edge of the preceding paper, B1 is the leading edge of the succeeding paper 1, B2 is the trailing edge of the succeeding paper 1, C1 is the leading edge of the succeeding paper 2, and C2 is the trailing paper 2. Represents the rear end of P1 represents paper, and progresses rightward on the paper surface as time passes. First, the sheet is conveyed at V1 having a high conveyance speed, and the sheet is temporarily stopped by the registration roller 112 to remove the skew of the conveyed sheet, and then conveyed at V2 having a low conveyance speed. It should be noted that the trailing edge A2 of the preceding sheet and the leading edge B1 of the succeeding sheet 1 are very close to each other in the vicinity of the registration roller 112. In other words, when performing catch-up control, it is necessary to carry out very accurate paper conveyance in the vicinity of the registration roller 112 that is a connecting portion of conveyance paths having different conveyance speeds.
[0057]
FIG. 3 is an explanatory diagram showing a state at the time of paper conveyance that has caused early arrival in the catch-up control.
[0058]
In FIG. 3, B1 indicated by a broken line is an ideal transport timing of the succeeding paper 1. However, when early arrival occurs, the transport is performed at an early time, so that the transport timing of the succeeding paper 1 is B1 '. It looks like a shift to the left. When the conveyance of the succeeding paper 1 is continued, the trailing edge A2 of the preceding paper and the leading edge B1 of the succeeding paper 1 overlap each other, and at this time, the leading edge of the succeeding paper 1 advances from the trailing edge of the preceding paper. This indicates that the paper is in a double feed. TIM0 (zero) is the time from the time when double feeding starts until the leading edge B1 of the succeeding sheet 1 arrives at the registration roller 112, which is the ideal transport timing of the succeeding sheet 1, and this TIM0 is the time for early arrival. .
[0059]
FIG. 5 is an explanatory side view showing the mechanism of occurrence of early arrival according to the present embodiment.
[0060]
In FIG. 5, a pickup roller 102 is provided on the transfer paper in the paper supply BOX 101 in which the transfer paper is stored to convey the transfer paper from the paper supply BOX 101 to the paper supply roller 103 and the separation roller 104. The sheet is in contact with the sheet, and the sheet is conveyed to the sheet feeding roller 103 by the rotational driving of the pickup roller 102. At this time, a frictional force is generated between the transfer papers due to static electricity, and there are cases where two sheets of paper are fed while being overlapped (double feed). In order to prevent this double feed, the paper feed roller 103 is installed in a pair with a separation roller 104 rotating in the opposite direction, and the first and second sheets are separated by a separation force greater than the friction between the sheets. Separate eyes. Even when the second and subsequent sheets can be separated, as shown in FIG. 5, the leading edge of the second sheet advances by a distance L from the predetermined leading edge position. In this case, the second sheet is detected early by the determination sensor installed in the downstream direction with respect to the sheet feeding position for a time T0 corresponding to the distance L.
[0061]
On the other hand, FIG. 4 shows a state of paper conveyance when a delay occurs. B1 indicated by a broken line is an ideal transport timing of the succeeding paper 1. However, if a delay occurs, the transport timing of the succeeding paper 1 is, for example, B1 ″. If the operation is continuously performed, the TIM2 becomes larger than the TIM1 that is an ideal conveyance interval for satisfying the productivity.
[0062]
As the cause of the delay, the roller diameter is reduced due to the wear of the transport roller due to durability etc., and the pressure to press the paper decreases, and as a result, the paper can not be firmly held, For example, the paper slip may occur or the roller diameter may be reduced, so that the roller circumference may be reduced correspondingly, and the paper transport distance may be reduced.
[0063]
FIG. 6 is a schematic diagram illustrating the paper conveyance path of the present embodiment, that is, a simplified diagram of the conveyance path of the image forming apparatus.
[0064]
Here, early arrival and delay detection means will be described.
[0065]
In FIG. 6, 110 indicates a preceding sheet and 111 indicates a succeeding sheet. Reference numeral 112 is a registration roller for removing the skew of the conveyed paper, and 113 is a detection means (sensor) for detecting the presence or absence of paper. Reference numeral 114 denotes a photosensitive drum. There is a situation in which the paper conveyance speed V1 upstream from the registration roller 112 with a broken line in the drawing is faster than the paper conveyance speed V2 downstream from the registration roller 112. In a state where the preceding paper 110 is being conveyed while being held between the photosensitive drum 114 and the registration roller 112 at the conveying speed V2, the succeeding paper 111 is conveyed at the conveying speed V1, and the detection means (sensor) 113 is turned on. At this time, the position of the succeeding sheet 111 with respect to the preceding sheet 110 is determined based on the data group held by the preceding sheet 110 and the succeeding sheet 111.
[0066]
Next, how the positional relationship between the preceding sheet and the succeeding sheet is determined will be described in detail with reference to FIG.
[0067]
FIG. 7 is a flowchart showing the operation of paper conveyance control according to the present embodiment, and shows how the sensor determines the positional relationship between the preceding paper and the succeeding paper.
[0068]
The sequence is started when the image forming apparatus starts image forming processing at the start.
[0069]
In step S1, it is detected whether or not the sensor 113 in FIG. 1 is turned on. If the sensor 113 continues to be turned off, the state is maintained until it is turned on. When the sensor 113 is turned on, it means that the paper has turned on the sensor 113 and it can be confirmed that the paper is present. Next, the process proceeds to step S2.
[0070]
In step S2, it is determined whether or not there is a preceding paper A for the paper whose presence is detected by the sensor 113 in step S1. The transported paper has a storage unit that stores the state of the paper itself. If the storage unit determines that there is no preceding paper A, the first sheet of the image forming processing job. Since it can be determined that there is, there is no need to care about the positional relationship with the previous paper, nothing is done, and the process proceeds to the next step S3.
[0071]
In step S3, it is determined that the target is achieved, and the process ends.
[0072]
If it is determined in step S4 that the preceding sheet A is present in the previous step S2, it is determined whether or not the preceding sheet A has passed the registration roller 112. If it is missing, the process proceeds to step S3, where it is determined as the target, and the process ends.
[0073]
If it is determined in step S4 that the preceding paper A has not passed through the registration roller 112, the process proceeds to the next step S5, where the time TA until the trailing edge of the preceding paper A passes through the registration roller 112 is set to a predetermined paper length. In addition, the situation is determined by taking into account the situation of conveyance at a predetermined conveyance speed. Then, the processing proceeds to scan STEP S6.
[0074]
In step S6, the time TB until the succeeding paper B arrives at the registration roller 112 is taken into account in the same manner as in the previous step S5 in consideration of the situation where the predetermined paper length is being transported at the predetermined transport speed. And determine. Next, the process proceeds to step S7.
[0075]
In step S7, the calculated time TA and time TB are compared. When it is determined that the time TA is large, the time TB at which the succeeding paper B arrives at the registration roller 112 is smaller and faster than the time TA until the trailing edge of the preceding paper A passes through the registration rollers 112. It is determined that so-called early arrival that catches up with the paper A has occurred. In this case, the process proceeds to step S8.
[0076]
In step S8, time TB is subtracted from time TA to obtain T1 which is an early arrival. Next, the process proceeds to step S9.
[0077]
In step S9, an early arrival sequence for correcting early arrival is performed based on T1 obtained in the previous step S8. After the sequence is completed, the entire control operation is terminated.
[0078]
On the other hand, if it is determined in step S7 that the time TA is small, it is determined that the following paper B arrives at the registration roller 112 very late, and it is determined that the IPM cannot be guaranteed. Proceed with the process.
[0079]
In step S10, the time TA is subtracted from the time TB to obtain the delay T2. Next, the process proceeds to step S11.
[0080]
In step S11, a delay sequence for correcting the delay is performed based on the delay T2 obtained in the previous step S10. After the sequence is finished, the entire control operation is finished.
[0081]
FIG. 8 is an explanatory diagram of early arrival sequence control for correcting early arrival according to the present embodiment. Hereinafter, the early arrival sequence control will be described with reference to FIG.
[0082]
The horizontal axis represents time, the vertical axis represents speed, and the area represents distance. For example, assume that the conveyance speed is 400 mm / sec. If the paper is continuously conveyed when the early arrival occurs, the registration roller 112 arrives as indicated by a broken line 1 in FIG. However, if the sensor for determining the distance from the preceding paper A determines that the subsequent paper B will arrive early, as indicated by the solid line 1 in order to delay the early arrival time, the conveyance speed → deceleration → stop → acceleration → The speed changes as follows: conveyance speed → registration sensor ON → deceleration → stop (registry arrival).
[0083]
The distance converted from the early arrival at that time is S (T1) below.
S (T1) = T1 (early arrival) x 400mm / sec (conveying speed)
Set the stop time to Y to correct the early arrival, and the distance taken by changing the speed of transport speed → deceleration → stop → acceleration → transport speed → registration sensor ON → deceleration → stop (registry arrival) The converted value is defined as S (Y) below.
[0084]
S (Y) = 31.7 msec (acceleration time) × 400 mm / sec (transport speed) ÷ 2 × 2 pieces + Y (stop time) × 400 mm / sec (transport speed)
The stop time Y is obtained by equalizing the S (T1) and S (Y), and the actual motor is stopped for the time Y to correct the early arrival. That is, since the distance from the sensor ON to the registration roller 112 is determined, the time is delayed by stopping the conveyance within the determined distance, and the early arrival T1 is eliminated.
[0085]
Regarding the delay, if the succeeding paper B (second sheet) is delayed with respect to the preceding paper A (first sheet), it is earlier than the normal conveyance start timing of the subsequent sheet C (third sheet). Start transport. In other words, the subsequent sheet C (third sheet) is conveyed early so that the registration ON interval from the succeeding sheet B (second sheet) to the subsequent sheet C (third sheet) is changed to a predetermined registration ON interval. . However, if the conveyance start timing of the subsequent sheet C (third sheet) is too early, the subsequent sheet C (third sheet) will arrive earlier than the subsequent sheet B (second sheet). The timing is calculated by the calculation means, and correction is performed so that the paper is conveyed from the next paper after the delayed paper at an optimum interval satisfying the productivity.
[0086]
In this embodiment, a program code for software that implements the functions of the above-described embodiments (for example, a program for executing various steps such as the processing in this embodiment described with reference to each drawing and the processing shown in the flowcharts). Is stored in a ROM (not shown) in the control unit of the image forming apparatus, and is read out and executed by the CPU in the control unit. As another form, for example, a memory in which the program code is recorded is stored. The medium may be supplied to the system or apparatus, and the computer (or CPU or MPU) of the system or apparatus may read and execute the program code stored in the storage medium.
[0087]
In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.
[0088]
As a storage medium for supplying the program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.
[0089]
Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) operating on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.
[0090]
Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.
[0091]
In the embodiment, the example in which the electrophotographic method using the laser beam is employed for the printing mechanism portion has been described. However, the present invention is not limited to this, and any printing method (for example, an LED printer, a thermal transfer printer, an inkjet printer, etc.) may be employed. Of course.
[0092]
【The invention's effect】
As described above, according to the present invention, high productivity can be realized at low cost. However, in catch-up control, which is paper transport control in which position management of the transported paper is difficult, the trailing edge of the preceding paper The leading edge of the succeeding paper causes double feeding, and printing is performed on the paper that has been overlapped at the time of image formation, and normal image formation cannot be realized. If the entry to the connecting part where the paper transport speed is slow is very delayed, the delay will be much later than the predetermined interval for satisfying the productivity, and the productivity cannot be satisfied. Troubles can be corrected flexibly and accurately, and even when used for a long period of time, paper can be transported with durability and reliability. It is possible to realize an image forming apparatus which guarantees the tee.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view showing a configuration of a main part of an image forming apparatus according to the present invention. FIG. 2 is an explanatory diagram showing a normal state during normal paper conveyance in catch-up control. Explanatory diagram showing the state during paper conveyance [FIG. 4] Explanatory diagram showing the state during paper conveyance that caused a delay in catch-up control [FIG. 5] An explanatory diagram showing the mechanism of early arrival in this embodiment [FIG. 6] FIG. 7 is a flowchart showing the operation of paper conveyance control according to the present embodiment. FIG. 8 is an explanatory diagram of early arrival sequence control for correcting early arrival according to the present embodiment. ]
DESCRIPTION OF SYMBOLS 10 Main body image output part 11 Main body image input part 12 Automatic document feeder 13 Sorter 21 Light sources 22-24 Mirror 25 Lens (input system)
26 CCD
27 Optical irradiation unit (laser)
28 Scanner 29 Lens (Output system)
30 Mirror 32 Fixing roller 33 Paper discharge tray 34, 35 Paper feed tray 36 Paper feed deck 37 Manual feed tray 38-42 Paper transport roller 101 Paper feed BOX
102 Pickup roller 103 Paper feed roller 104 Separating rollers 105, 106 Conveying path 107 Subsequent paper 108 Preceding paper a Conveying direction L Distance T0 at which the following paper advances with respect to a predetermined paper leading edge position Distance L converted into time 110 Preceding Paper 111 Subsequent paper 112 Registration roller 112
113 Sensor 114 Photosensitive drum 115 Broken line V1 Paper conveyance speed upstream of registration roller 112 V2 Paper conveyance speed downstream of registration roller 112 Broken line 1 State when paper is continuously conveyed when early arrival occurs Solid line 1 Early State when paper is conveyed to correct arrival T1 Time S for early arrival S (T1) Distance converted from time T1 for early arrival Y Stop conveyance to apply early arrival correction Time S (Y) when the total time required for early arrival correction is converted into distance P1 preceding paper A1 leading edge A2 preceding paper trailing edge B1 trailing paper 1 leading edge B2 trailing paper 1 trailing edge C1 The leading edge C2 of the succeeding paper 2 The trailing edge B1 ′ of the succeeding paper 2 The leading edge B1 ″ of the succeeding paper 1 when the succeeding paper 1 has arrived early. The leading edge TIM0 of the succeeding paper 1 when the succeeding paper 1 has delayed. From the time when Conveying interval when virtual is a conveyance timing of the subsequent paper sheet 1 of B1 has caused an ideal conveyance interval TIM2 delay to satisfy the time TIM1 productivity until passing through the registration roller 112

Claims (2)

A paper storage section for storing paper;
Paper feeding means for feeding the paper stored in the paper storage unit one by one;
First transport means for transporting paper fed by the paper feed means;
Detecting means for detecting the presence or absence of paper conveyed by the first conveying means ;
A second conveying means that is provided downstream of the first conveying means and conveys the sheet at a speed slower than the conveying speed of the first conveying means;
The time TA until the trailing edge of the preceding sheet conveyed preceding the succeeding sheet exits the second conveying unit when the leading end of the succeeding sheet conveyed subsequently by the detecting unit is detected, and the time Time indexing means for determining the time TB until the leading edge of the succeeding paper arrives at the second transport means;
Determining means for determining whether or not the leading edge of the succeeding sheet catches up with the trailing edge of the preceding sheet based on a difference time between the time TA and the time TB calculated by the time indexing unit;
When it is determined by the determination means that the leading edge of the succeeding sheet catches up with the trailing edge of the preceding sheet, the first conveyance is performed so as to delay the arrival at the second conveyance unit by a time corresponding to the difference time. Conveyance control means for temporarily stopping conveyance of the subsequent sheet by the means;
An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the determination unit determines that the leading edge of the succeeding sheet catches up with the trailing edge of the preceding sheet when the time TA is greater than the time TB. Image forming apparatus.

Images