JP2001206583A - Image forming device, feed speed determining method, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently improve productivity while ensuring high printing accuracy even under the same process speed, by shortening the distance between paper sheets and preventing a jam via a simple structure. SOLUTION: When a plurality of paper sheets are fed in one-by-one separation (S501) and a determination sensor detects the paper sheets fed (YES in S502), the difference is detected between the detection timing and the timing to be detected in the normal condition (S507). In accordance with the difference, feed speed is determined for a register-upstream roller disposed in the upstream side of a register roller, and the register-upstream roller is driven at the feed speed (S509). If the detection timing is earlier than the normal timing, the feed of the register-upstream roller is slowed down (S509), so that the paper sheets are delivered to registering means at the same timing as in the normal condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, a conveyance speed determining method, and a storage medium, and more particularly, it is possible to form the same image on a plurality of sheets based on image information stored in the storage device. The present invention relates to a simple image forming apparatus, a conveyance speed determining method applied to the image forming apparatus, and a storage medium storing a program for executing the conveyance speed determining method.

[0002] The image forming apparatus is an image forming apparatus such as a copying machine or a printer.

[0003]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, the position (orientation) of a sheet is adjusted immediately before an image forming section in a sheet (recording sheet) conveying path.
In some cases, registration means is used to synchronize with a transferred image.

There are various methods as these registration means, but a loop registration method is widely and generally employed as a particularly inexpensive, reliable, and simpler configuration means. According to this loop registration method, the sheet tip is brought into contact with the nip of the stopped registration roller pair to make the sheet flex, and the sheet tip is made to follow the roller nip by the elasticity of the sheet, thereby correcting the skew of the sheet. The rotation of the pair of registration rollers is started at a predetermined timing, thereby synchronizing the encounter between the transferred image and the sheet.

When a plurality of copies of the same document are made by a conventional analog copying machine, an optical device for exposing the document reciprocates with respect to the document surface by the number of copies.
Such a reciprocating motion includes a period in which no exposure is performed for each reciprocation, and in this period, sheet conveyance is interrupted (between sheets). Therefore, the above-described registration means may be operated in the period. .

On the other hand, in recent years, reading of an original and image formation thereof have been digitized in an image forming apparatus. Here, image information of the original is electrically encoded and stored in a memory. Is read, and an image corresponding to the image information of the document is formed on the photosensitive member by an exposure device such as a laser beam or an LED array. Since the image information of the document is stored in the memory as described above, the digital image forming apparatus does not require a mechanical reciprocating operation of the optical device when copying a plurality of the same document.

Therefore, it is possible to shorten the conveyance interval (sheet interval) between the sheets and to perform transfer processing on many sheets in a short time, thereby substantially increasing the speed without increasing the image forming process speed. Can be realized, and the productivity can be improved.

[0008]

However, in the above-described conventional digital image forming apparatus, if the sheet conveyance interval (paper interval) is shortened, the following problems occur.

That is, in the case of the loop registration method, the sheet is temporarily stopped by the registration roller.
Originally, the sheet interval becomes shorter than the sheet interval (process sheet interval) in the downstream portion. Nevertheless, if the paper interval is shortened as described above on the upstream side of the registration roller section, the next sheet collides with the preceding sheet waiting for skew feeding correction and image synchronization by the registration roller. There is a risk of jamming.

The registration roller stops its rotation when the preceding sheet passes through the registration roller and prepares for the next sheet. However, when the sheet interval is set short, the rotation of the registration roller does not stop. The next sheet may come in at home. In this case, the leading edge of the next sheet cannot be aligned with the nip of the pair of registration rollers, so that skew correction and image synchronization cannot be performed. It becomes an image.

FIG. 1 is a view showing the structure of an image forming apparatus as will be described later. For example, as shown in FIG.
Than the distance l ₂ of the transport path up to the distance l ₁ from the exposure position 112b on the photosensitive drum 112 to the transfer position 112a
In the image forming apparatus having the longer configuration, the exposure is started earlier than the drive start timing of the registration roller 106. Therefore, if the sheet does not arrive at the registration roller by the timing of starting the driving of the registration roller due to some problem, that is, if the conveyance of the sheet is delayed, the sheet can be synchronized with the image on the photosensitive drum. However, this delay has an allowable time width, and synchronization can be performed with a certain delay time. However, as described above, when the sheet interval is shortened, the allowable time width is narrowed, synchronization cannot be achieved even with a slight delay, and as a result, printing accuracy cannot be secured, resulting in an extremely unsightly image. .

As described above, there is a limit to shortening the sheet interval.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and the paper interval can be further reduced with a simple configuration, and no jam occurs, and even if the process speed is the same, the paper interval is high. An object of the present invention is to provide an image forming apparatus, a conveyance speed determining method, and a storage medium that can efficiently improve productivity while ensuring printing accuracy.

[0014]

According to the first aspect of the present invention, the same image can be formed on a plurality of sheets based on image information stored in a storage device. A paper feed unit for separating and feeding a plurality of sheets one by one, and a variable conveyance speed independent of the paper feed speed of the paper feed unit. Transport means for transporting the transported sheet, resist means for correcting skew of the paper transported by the transport means, and paper feed means disposed in a paper transport path from the paper feed means to the resist means. Paper detecting means for detecting the paper fed by the paper detecting means, and speed determining means for determining a transport speed of the transport means based on a paper detection timing at which the paper detecting means detects the paper.

According to the twelfth aspect of the present invention, there is provided a sheet feeding means for separating and feeding a plurality of sheets one by one, and a variable conveying speed independent of the sheet feeding speed of the sheet feeding means. Transport means for transporting the paper fed by the paper feed means; resist means for correcting skew of the paper transported by the transport means; and a paper transport path from the paper feed means to the resist means And paper detecting means for detecting the paper fed by the paper feeding means, and the same image can be formed on a plurality of papers based on the image information stored in the storage device. In a carrying speed determining method applied to an image forming apparatus, a sheet detecting step in which the sheet detecting unit detects a sheet fed by the sheet feeding unit, and a sheet detecting time when the sheet detecting unit detects a sheet. And having a speed determination step of determining the conveying speed of the conveying means on the basis of the grayed.

Furthermore, according to the invention of claim 23,
A sheet feeding unit that separates and feeds a plurality of sheets one by one; and a variable conveyance speed independent of the sheet feeding speed of the sheet feeding unit, and conveys the sheet fed by the sheet feeding unit. Conveyance means, registration means for correcting skew of the paper conveyed by the conveyance means, and a paper sheet disposed in a paper conveyance path from the paper supply means to the registration means and fed by the paper supply means And a sheet detecting means for detecting a sheet speed. A conveying speed determination method applied to an image forming apparatus capable of forming the same image on a plurality of sheets based on image information stored in a storage device is stored as a program. In the computer-readable storage medium, the transport speed determining method includes a sheet detecting step in which the sheet detecting unit detects a sheet fed by the sheet feeding unit; Sheet detection means and having a rate determining step of determining a conveying speed of said conveying means based on a sheet detection timing of detecting the paper.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view showing the structure of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of the image forming apparatus. Hereinafter, description will be made with reference to FIGS.

The image forming apparatus mainly includes a printer 1000 and a scanner 2000. Printer 1000
Is controlled by the controller 120.

In the printer 1000, reference numeral 100 denotes an upper cassette for storing sheets.
The sheet inside is separated by a separation claw (not shown) and a sheet feeding roller 101.
The sheets are separated and fed one by one, guided by a guide plate (not shown), and guided to a pair of transport rollers 105, a pair of pre-registration rollers 107, and a pair of registration rollers 106.

Reference numeral 102 denotes a lower cassette for storing sheets. The sheets in the lower cassette 102 are separated one by one by the action of a separation claw (not shown) and a paper feed roller 103, similarly to the case of the upper cassette 100. While being fed and guided by a guide plate (not shown), it is delivered to a pair of transport rollers 104 and guided to a transport roller 105, a pre-registration roller 107, and a registration roller 106.

Each of the rollers 101, 103-1
Reference numeral 06 denotes a driving force received by a main motor M (not shown). Each ON / OFF control is performed by a clutch (CL) 101b, 103b to 106b via a drive circuit 101a, 103a to 106a, and a signal from a controller 120. It is configured to be made.
The pre-registration roller 107 is provided with a pre-registration motor drive circuit 1.
07a is configured to be speed-controlled.

A registration sensor 108 and a determination sensor 109 are arranged in a sheet conveyance path from the cassettes 100 and 102 to the registration roller 106. The determination sensor 109 controls exposure start timing described below,
It is used for controlling sheet feeding from the cassettes 100 and 102 to the registration rollers 106. The registration sensor 108 is arranged on the upstream side of the registration roller 106 in the transport direction, and is used for controlling the registration roller 106 when forming a loop described later. Each of the sensors 108 and 109 is constituted by a photo interrupter and a sensor flag (not shown). The sheet abuts on the sensor flag and is rotated to detect that the sheet has reached the sensor. is there. Output signals from these sensors are input to the controller 120.

Reference numeral 112 denotes a photosensitive drum which rotates clockwise in the figure. Reference numeral 111 denotes a laser modulator (laser scanner). The laser light output from the laser modulator is turned back by a mirror 113 and irradiated on an exposure position 112 b on the photosensitive drum 112 to form a latent image on the photosensitive drum 112. This latent image is visualized as a toner image by the developing device 114. Reference numeral 115 denotes a transfer charger for transferring the toner image on the photosensitive drum 112 to the sheet, and 116 denotes a separation charger for electrostatically separating the photosensitive drum 112 and the sheet, and both constitute an image forming unit. Reference numeral 112a denotes a transfer position on the photosensitive drum 112, and at this position, the toner image on the photosensitive drum 112 is transferred to a sheet.

Reference numeral 117 denotes a conveyance belt for conveying the sheet material on which an image is formed, 118 denotes a fixing device, and 119 denotes a paper discharge roller. The sheet material on which the image is formed is discharged to the sorter 2 by the discharge roller 119.

Next, the scanner 2000 will be described.

In the scanner 2000, 201 is a scanning optical system light source, 202 is a platen glass, 203 is an original platen that opens and closes, 204 is a lens, 205 is a light receiving element (photoelectric conversion element), 206 is an image processing unit, and 208 is image processing. This is a memory for storing the image signal processed by the unit 206.

The original image read by the light receiving element 205 is processed by the image processing unit 206, electrically encoded, converted into an electric signal 207, and transmitted to the laser modulator 111. Further, the image information processed and encoded by the image processing unit 206 may be temporarily stored in the memory 208, read out as necessary according to a signal from the controller 120, and transmitted to the laser modulator 111. It is composed of

The printer 1 constituting the image forming apparatus
Although the printer 1000 and the scanner 2000 are separate from each other in the embodiment shown in FIG. 1, the printer 1000 and the scanner 2000 may be integrated. Also, the printer 100
When the output signal of the image processing unit 206 is input to the laser modulator 111 regardless of whether the scanner 0 and the scanner 2000 are separate or integrated, the image forming apparatus functions as a copying machine,
When a facsimile reception signal is input to the laser modulator 111, the printer 1000 functions as a facsimile reception unit. When an output signal of a personal computer is input to the laser modulator 111, the printer 1000 functions as a printer for a personal computer. Is also possible. Further, the image processing unit 2
If the output signal 06 is used as a facsimile transmission signal, the scanner 2000 functions as a part of the facsimile transmission unit.

If an automatic document feeder 250 as shown by a dashed line in FIG. 1 is mounted instead of the document pressure plate 203, the document is automatically read.

Next, the control of the image forming apparatus of the present invention will be described in detail.

FIG. 3 is a timing chart showing a state in which a sheet sent from the cassette 100 is conveyed in a normal state. The vertical axis indicates distance, and the horizontal axis indicates time.

As shown in the figure, a sheet (sheet) that has been started to be fed at a predetermined feeding timing is conveyed at a predetermined conveying speed, passes through conveying rollers 105, and is determined at time T0 from the start. The sensor 109 detects the leading edge of the sheet. This time T0 is a theoretical time from the start of sheet feeding until the leading edge of the sheet reaches the determination sensor 109. If there is no early arrival or delay, the sheet is passed through the determination sensor 109 at time T0. It is set in advance.

At the time T0, the leading edge of the sheet is determined by the sensor 109.
, The pre-registration roller 107 conveys the sheet at a predetermined conveying speed V, and hits the sheet against the stopped registration roller 106. The conveyance of the sheet is stopped here, and after a lapse of a predetermined time (t1), the registration CL (clutch) 106b is turned on, thereby driving the registration roller 106 and restarting the conveyance. Here resist C
The timing of turning on L106b is determined by the registration sensor 10
8 is set after the time t0 from the detection of the leading edge of the sheet.

A time t2 from the time when the resist CL 106b is turned on to the time when the resist CL 106b is turned on for the next sheet is an interval of sheet conveyance (inter-sheet interval) in the image forming apparatus. The resist C is kept constant, that is, at regular time intervals.
Control is performed so that L106b can be turned ON. If the resist CL 106b cannot be turned on at regular time intervals due to exceeding the controllable range,
Control is performed to minimize the deviation.

(Early Arrival Control) FIG. 4 and FIG. 5 show the control in the case where the paper which has started the paper feeding operation has passed through the determination sensor 109 without waiting for the lapse of the time T0. I will explain. FIG. 4 is a diagram showing the sheet conveyance timing when the early arrival occurs, and FIG.
It is a flowchart which shows the procedure of the process at the time of the early arrival which is performed by.

When it is time to start paper conveyance, the controller 120 drives the main motor M122 via the main motor M drive circuit 121. Main motor M122
When the rotation of has become a steady state, the paper feed CL 101b and the transport CL 105b are turned on. As a result, the paper feed roller 101 rotates and the paper in the upper cassette 100 starts to be fed (S501), and the transport roller 105 starts rotating.

When the paper feeding operation is started, the controller 12
A value of 0 determines whether the leading edge of the sheet has reached the determination sensor 109 based on the output of the determination sensor 109 (S502). If the leading edge of the sheet has not yet arrived, it is determined whether or not a time T0 as a reference time has elapsed from the sheet feeding start timing (S503). If the time T0 has not elapsed, the leading edge of the sheet is again determined by the determination sensor 109. Is determined (S502). If it is determined in step S503 that the time T0 has already elapsed, the control of the controller 120 is switched to “delay control” described below (S504).

In step S502, when it is detected that the leading edge of the sheet has reached the determination sensor 109, the controller 120 determines that the time T1, which is the maximum limit time for which early arrival correction can be performed, has elapsed since the start of sheet feeding. It is determined whether or not there is (S505). If the time T1 has not yet elapsed, normal paper conveyance cannot be performed even if the deceleration control of the pre-registration motor described later is used, so that the paper conveyance is stopped, and the fact that the paper is jammed is notified via a display screen or the like (not shown). The user is notified (S506).

If it is determined in step S505 that the time T1 has elapsed since the start of sheet feeding, the early arrival time T 'with respect to the time T0 is calculated and stored in the controller 120 (S507). Next, the controller 120
Indicates that the leading edge of the sheet is detected from the determination sensor 109 by the roller
The time tA required to move to 07 is calculated, and based on this time tA, it is waited that the leading edge of the sheet reaches the pre-registration roller 107 (S508).

The time tA (sec) is determined by the determination sensor 10
Assuming that the distance between the roller 9 and the pre-registration roller 107 is X (mm) and the paper transport speed of the transport roller 105 is V (mm / sec), the following equation (1) is used.

TA = X / V (1) After the elapse of the time tA, it is considered that the leading edge of the sheet has arrived at the pre-registration roller 107.
0 controls the speed of the pre-registration roller 107 via the pre-registration motor drive circuit 107a (S509). That is, the pre-registration roller 1 is controlled so that the time required when the sheet is conveyed from the pre-registration roller 107 to the registration sensor 108 is longer than the normal paper conveyance time by the stored quick arrival time T ′.
07 is decelerated.

Assuming that the reduced transport speed of the pre-registration roller 107 is Z (mm / sec) and the distance from the pre-registration roller 107 to the registration sensor 108 is Y (mm), the early arrival time T '(sec) is as follows. It is represented by equation (2).

T ′ = Y / Z−Y / V (2) From this equation (2), the transport speed Z can be derived as in the following equation (3).

Z = 1 / (T ′ / Y + 1 / V) (3) That is, the transport speed of the pre-registration roller 107 is obtained from the above equation (3), and the paper is transported at the transport speed Z. I do. As a result, the early arrival paper also reaches the registration sensor 108 at the same timing as when the reference paper in the normal conveyance state would reach the registration sensor 108.

If, for example, Z = V / 2, the following equation (4) is derived from the above equation (3).

T ′ = Y / V (4) Therefore, by setting the transport speed Z of the pre-registration roller 107 to half the normal transport speed V (same as the paper transport speed of the transport roller 105), Correction can be made for the early arrival time of the length of Y / V.

As shown by the solid line in FIG. 4, the early arrival control decelerates the quickly arrived sheet from the point where it reaches the pre-registration roller 107, and the timing at which the leading edge of the reference sheet indicated by the dotted line reaches the registration sensor 108. At the same timing as above, the leading edge of the sheet reaches the registration sensor 108.

When each sheet arrives early, this early arrival control is repeated for each sheet so that the time t shown in FIG.
2 can be kept constant.

(Delay Control) Next, FIGS. 6 to 8 show the control in the case where a delay occurs such that the sheet that has started the sheet feeding operation passes through the determination sensor 109 after the elapse of the time T0.
This will be described with reference to FIG. 6 and 7 are diagrams showing the sheet transport timing when a delay occurs, and FIG.
9 is a flowchart illustrating a procedure of a process performed when a delay occurs, which is executed in Step 20. FIG. 6 shows the sheet conveyance timing when a correctable delay has occurred, and FIG. 7 shows the sheet conveyance timing when an uncorrectable delay has occurred.

First, a description will be given with reference to FIGS.

When the sheet conveyance start time comes, the controller 120 drives the main motor M122 via the main motor M drive circuit 121. Main motor M122
When the rotation of has become a steady state, the paper feed CL 101b and the transport CL 105b are turned on. As a result, the paper feed roller 101 rotates and starts feeding paper in the upper cassette 100 (S801), and the transport roller 105 starts rotating.

When the paper feeding operation is started, the controller 12
A value of 0 determines whether the leading edge of the sheet has reached the determination sensor 109 based on the output of the determination sensor 109 (S802). If the leading edge of the sheet has not yet arrived, it is determined whether or not the time T3, which is the delay limit time, has elapsed since the start of sheet feeding (S803). It is determined whether or not it has reached (S802). Step S8
03, when it is confirmed that the time T3 has already passed, it is determined that the interval between the next conveyed sheet has already disappeared and it is not in a state where normal sheet conveyance can be performed, and the sheet conveyance is performed. Is stopped and the user is notified of the paper jam via a display screen (not shown) or the like (S
804).

In step S802, when it is detected that the leading edge of the sheet has reached the determination sensor 109, the controller 120 determines that the delay control boundary time T2, which is the maximum limit time for which delay correction can be performed, has elapsed since the start of sheet feeding. It is determined whether or not it has been performed (S805). Still time T2
Does not elapse, the delay time T "with respect to the reference time T0 is calculated and stored in the controller 120 (S8).
06). Next, the controller 120 calculates a time tA required for the leading edge of the paper to move from the determination sensor 109 to the pre-registration roller 107, and waits for the leading edge of the paper to reach the pre-registration roller 107 based on the time tA. (S
807).

The time tA (sec) is determined by the judgment sensor 10
Assuming that the distance between the roller 9 and the pre-registration roller 107 is X (mm) and the paper transport speed of the transport roller 105 is V (mm / sec), the following equation (5) is used.

TA = X / V (5) After the elapse of the time tA, it is considered that the leading edge of the sheet has reached the pre-registration roller 107, and then the controller 12
0 controls the speed of the pre-registration roller 107 via the pre-registration motor drive circuit 107a (S808). That is, the pre-registration roller 10 is moved so that the time required when the sheet is conveyed from the pre-registration roller 107 to the registration sensor 108 is shorter than the normal paper conveyance time by the stored delay time T ″.
7 is performed.

Assuming that the increased transport speed of the pre-registration roller 107 is Z (mm / sec) and the distance from the pre-registration roller 107 to the registration sensor 108 is Y (mm), the delay time T ″ (sec) is as follows. It is represented by equation (6).

T ″ = Y / V−Y / Z (6) From this equation (6), the transport speed Z can be derived as in the following equation (7).

Z = 1 / (1 / VT− / Y) (7) That is, the transport speed of the pre-registration roller 107 is obtained from the above equation (7), and the paper is transported at the transport speed Z. In this way, the delayed sheet also reaches the registration sensor 108 at the same timing that the reference sheet in the normal conveyance state would reach the registration sensor 108.

If, for example, Z = 2V, the following equation (8) is derived from the above equation (7).

T ″ = Y / 2V (8) Therefore, by setting the transport speed Z of the pre-registration roller 107 to twice the normal transport speed V (the same as the paper transport speed of the transport roller 105), , Y / 2V.

With this delay control, as shown by the solid line in FIG. 6, the speed of the delayed sheet is increased from the point where it reaches the pre-registration roller 107, and the timing at which the leading edge of the reference sheet indicated by the dotted line reaches the registration sensor 108 is determined. At the same timing, the leading end of the sheet reaches the registration sensor 108.

When each sheet is delayed, by repeating this delay control for each sheet, the time t shown in FIG.
2 can be kept constant.

Next, a description will be given with reference to FIGS.

If it is determined in step S805 that the delay control boundary time T2 has elapsed, the flow advances to step S809 to calculate the maximum speed increase control time t4, which is the difference between the time T2 and the time T0. And the time T required for the leading edge of the paper to reach the determination sensor 109 from
A time t5, which is a difference from 2, is calculated, and the times t4 and t5 are stored in the controller 120. The time t5 is a time in which the roller 107 cannot be recovered even if the pre-registration roller 107 is controlled to the maximum speed.

Next, the controller 120 calculates the time tA required for the leading edge of the sheet to move from the determination sensor 109 to the pre-registration roller 107, and based on this time tA, the leading edge of the sheet reaches the pre-registration roller 107. Wait for that (S810).

The time tA (sec) is determined by the judgment sensor 10
Assuming that the distance between the roller 9 and the pre-registration roller 107 is X (mm) and the paper transport speed of the transport roller 105 is V (mm / sec), the following equation (9) is used.

TA = X / V (9) After the lapse of the time tA, it is considered that the leading edge of the sheet has reached the pre-registration roller 107, and then the controller 12
0 controls the maximum speed of the pre-registration roller 107 via the pre-registration motor drive circuit 107a (S811). That is,
The pre-registration roller 107 is driven at an increased speed so that the time required when the paper is conveyed from the pre-registration roller 107 to the registration sensor 108 is shorter than the normal paper conveyance time by the stored delay time t4.

Assuming that the increased transport speed of the pre-registration roller 107 is Z (mm / sec) and the distance from the pre-registration roller 107 to the registration sensor 108 is Y (mm), the delay time t4 (sec) is given by the following equation. It is represented by (10).

T4 = Y / V−Y / Z (10) From this equation (10), the transport speed Z can be derived as in the following equation (11).

Z = 1 / (1 / V−t4 / Y) (11) Since t4 = T2−T0, the equation (11) is expressed as the following equation (12).

Z = 1 / [1 / V− (T2−T0) / Y] (12) That is, the pre-registration roller 107 is driven at the maximum transport speed determined by the above equation (12) to delay. Try to transport the paper. As a result, the leading end of the delayed sheet reaches the registration sensor 108 with a delay of time t5 from the timing at which the reference sheet in the normal conveyance state would reach the registration sensor 108.

By this delay control, as shown by the solid line in FIG. 7, the delayed sheet is transported at the maximum possible transport speed from the point where it reaches the pre-registration roller 107, and the leading edge of the reference sheet shown by the dotted line is sent to the registration sensor 108. It arrives at the registration sensor 108 with a delay of time t5 from the arrival timing.

Therefore, the timing of turning on the resist CL 106b is delayed by the time t5, and the exposure timing of the photosensitive drum 112 is also delayed by the time t5. Further, since the distance between the next sheet and the next sheet becomes narrower, the feeding timing of the next sheet is delayed by the time t5 (S81).
2).

By doing so, the time t2 shown in FIG.
Becomes (t2 + t5), but the minimum delay amount t with respect to the time (t4 + t5) when the paper is actually delayed
5, the image can be formed without causing a jam or deterioration of the image quality. In this way, even if the image formation is delayed, the image forming apparatus is stopped due to a paper jam or the like, and the productivity is significantly reduced, or the unsightly image having a significantly poor printing accuracy is provided. The present invention can improve the productivity by a much higher level than that in which the user performs the copy operation again.

(Second Embodiment) Next, a second embodiment will be described.

Since the configuration of the second embodiment is basically the same as the configuration of the first embodiment, the configuration of the first embodiment will be used in the description of the second embodiment.

In the first embodiment, the photosensitive drum 1
Exposure start timing for the registration roller 1
While 06 is assumed to be the after drive timing, in the second embodiment, than the distance l ₂ from the resist rollers 106 shown in FIG. 1 to the transfer position 112a, to the transfer position 112a from the exposure start position 112b Distance l
_{The case in which 1} is longer and therefore the exposure start timing for the photosensitive drum 112 is earlier than the drive timing of the registration roller 106 will be described.

FIG. 9 is a timing chart showing a state in which the sheet sent from the cassette 100 is transported in a normal state. The vertical axis indicates distance, and the horizontal axis indicates time.

As shown in the figure, a sheet (sheet) which is started to be fed at a predetermined feeding timing is conveyed at a predetermined conveying speed, passes through conveying rollers 105, and is determined at time T0 from the start. The sensor 109 detects the leading edge of the sheet. This time T0 is a theoretical time from the start of sheet feeding until the leading edge of the sheet reaches the determination sensor 109. If there is no early arrival or delay, the sheet is passed through the determination sensor 109 at time T0. It is set in advance.

At time T0, the leading edge of the sheet is determined by sensor 109.
, The pre-registration roller 107 conveys the sheet at a predetermined conveying speed V, and hits the sheet against the stopped registration roller 106. The conveyance of the sheet is stopped here, and after a lapse of a predetermined time (t1), the registration CL (clutch) 106b is turned on, thereby driving the registration roller 106 and restarting the conveyance. Here resist C
The timing of turning on L106b is determined by the registration sensor 10
8 is set after the time t0 from the detection of the leading edge of the sheet.

In the second embodiment, the distance l ₁ from the exposure start position 112b on the photosensitive drum 112 to the transfer position 112a is longer than the distance l ₂ from the registration roller 106 to the transfer position 112a. Therefore, exposure cannot be started in synchronization with the drive start timing of the registration roller 106. That is, the exposure start timing is set at the transfer position 1 on the upstream side of the registration roller 106.
Position of the transfer path from 12a the distance l ₁ shall timing (timing after time T4 has elapsed from the sheet feed start) when the sheet leading end (position A in FIG. 9) is located. Under these circumstances, the time from the exposure start timing to the timing at which the leading edge of the sheet reaches the transfer position 112a via the registration sensor 108 and the registration roller 106 must always be constant. If this time is not constant, the image will not be transferred to the normal position with respect to the paper, and there will be problems such as too much margin at the leading or trailing edge of the paper, or the leading or trailing edge of the image may be cut off. I will.

Further, similarly to the first embodiment, if the time t2, which is the time interval for turning on the resist CL106b, is shortened, a failure such as collision with the preceding sheet occurs, and if the time t2 is lengthened. This leads to a decrease in productivity such as a decrease in the number of processed sheets per unit time.

In the second embodiment, the time t2 is always kept constant, and the paper transport time from the exposure start timing to the timing when the paper reaches the transfer position is always kept constant. Also in the second embodiment, if the time t2 cannot be kept constant and becomes longer, the extension is kept to a minimum so as to prevent a decrease in productivity as much as possible. This will be described below.

(Early Arrival Control) FIG. 10 and FIG. 11 show the control in the case where the paper which has started the paper feeding operation has passed through the determination sensor 109 without waiting for the time T0 to elapse. I will explain. FIG. 10 is a diagram showing the sheet transport timing at the time of early arrival, and FIG. 11 is a flowchart showing the procedure of processing at the time of early arrival performed by the controller 120.

When the sheet conveyance start time comes, the controller 120 drives the main motor M122 via the main motor M drive circuit 121. Main motor M122
When the rotation of has become a steady state, the paper feed CL 101b and the transport CL 105b are turned on. As a result, the paper feed roller 101 rotates and starts feeding paper in the upper cassette 100 (S1101), and the transport roller 105 starts rotating. Also, the photosensitive drum 1
The timing for starting exposure for forming a latent image on the image 12 is set (S1102). This timing is set after a lapse of time T4 from the paper feed start timing.

When the sheet feeding operation is started, the controller 12
A value of 0 determines whether the leading edge of the sheet has reached the determination sensor 109 based on the output of the determination sensor 109 (S1103). If the leading edge of the paper has not yet reached
It is determined whether or not the time T0, which is the reference time, has elapsed from the sheet feeding start timing (S1104). If the time T0 has not elapsed, the leading edge of the sheet is again determined by the determination sensor 10.
9 is determined (S110).
3). If it is determined in step S1104 that the time T0 has already elapsed, the control of the controller 120 is switched to “delay control” described below (S1).
105).

In step S1103, when it is detected that the leading edge of the sheet has reached the determination sensor 109, the controller 120 determines that the time T1, which is the maximum limit time for which early arrival correction can be performed, has elapsed since the start of sheet feeding. It is determined whether or not there is (S1106). If the time T1 has not elapsed yet, normal paper transport cannot be performed, and the paper transport is stopped, and the user is notified of a paper jam via a display screen (not shown) or the like (S1107).

If it is determined in step S1106 that the time T1 has elapsed since the start of sheet feeding, the time T0
Is calculated and stored in the controller 120 (S1108). Next, the controller 12
A value of 0 calculates the time tA required for the leading edge of the paper to move from the determination sensor 109 to the pre-registration roller 107, and waits for the leading edge of the paper to reach the pre-registration roller 107 based on this time tA (S1109).

The time tA (sec) is determined by the judgment sensor 10
Assuming that the distance between the roller 9 and the pre-registration roller 107 is X (mm), and the paper transport speed of the transport roller 105 is V (mm / sec), the following equation (13) is used.

TA = X / V (13) After the elapse of the time tA, it is considered that the leading edge of the sheet has arrived at the pre-registration roller 107.
In the case of 0, the pre-registration roller 107 is decelerated through the pre-registration motor drive circuit 107a (S1110). That is, the pre-registration roller 107 is decelerated so that the time required when the sheet is conveyed from the pre-registration roller 107 to the registration sensor 108 is longer than the normal paper conveyance time by the stored quick arrival time T ′. I do.

Assuming that the reduced transport speed of the pre-registration roller 107 is Z (mm / sec) and the distance from the pre-registration roller 107 to the registration sensor 108 is Y (mm), the early arrival time T ′ (sec) is as follows. It is represented by equation (14).

T ′ = Y / Z−Y / V (14) From this equation (14), the transport speed Z can be derived as in the following equation (15).

Z = 1 / (T ′ / Y + 1 / V) (15) That is, the transport speed of the pre-registration roller 107 is calculated by the above equation (1).
5), the sheet is conveyed at the conveying speed Z. With this, the early arrival paper is also registered with the registration sensor 1 at the same timing that the reference paper in the normal conveyance state would reach the registration sensor 108.
08 is reached.

If, for example, Z = V / 2, the following equation (16) is derived from the above equation (15).

T ′ = Y / V (16) Therefore, by setting the transport speed Z of the pre-registration roller 107 to half of the transport speed V in the normal state (the same as the paper transport speed of the transport roller 105), Correction can be made for the early arrival time of the length of Y / V.

When the deceleration control is started, it is checked whether or not T4, which is the time from the sheet feeding start timing to the exposure start timing, has elapsed, and the process waits until the time T4 has elapsed (S1111). When it is confirmed that the time T4 has elapsed, an enable signal is transmitted to the memory 208 to read out image information, and based on the image information,
Exposure to the photosensitive drum 112 is started via the laser modulator 111 (S1112).

By this early arrival control, as shown by the solid line in FIG. 10, the quickly arrived sheet is decelerated from the point where it reaches the pre-registration roller 107, and the timing at which the leading edge of the reference sheet indicated by the dotted line reaches the registration sensor 108. At the same timing as above, the leading edge of the sheet reaches the registration sensor 108.

When each sheet arrives early, this early arrival control is repeated for each sheet, so that the time t shown in FIG.
2 can be kept constant.

Further, the exposure start timing is set to a timing (feeding start) when the leading end of the reference sheet (shown by a dotted line) is located at a position (position A in FIG. 10) on the transport path which is a distance l ₁ from the transfer position 112a. (The timing after the elapse of the time T4 from the start), the exposure start timing is set irrespective of the early arrival of the sheet. Therefore, the image is transferred to a normal position with respect to the sheet, and there is no trouble such as too much margin at the leading or trailing edge of the sheet, or the leading or trailing edge of the image is cut off.

(Delay Control) Next, the control in the case where a delay occurs such that the sheet that has started the sheet feeding operation passes through the determination sensor 109 after the elapse of the time T0 will be described with reference to FIGS. I do. FIG. 12 and FIG. 13 are diagrams showing the sheet conveyance timing when a delay occurs, and FIG. 14 is a flowchart showing a procedure of processing performed by the controller 120 when a delay occurs. FIG. 12 shows the sheet conveyance timing when a correctable delay occurs, and FIG.
Indicates the paper transport timing when an uncorrectable delay occurs.

First, a description will be given with reference to FIGS.

At the sheet conveyance start timing, the controller 120 drives the main motor M122 via the main motor M drive circuit 121. Main motor M122
When the rotation of has become a steady state, the paper feed CL 101b and the transport CL 105b are turned on. As a result, the paper feed roller 101 rotates and starts feeding paper in the upper cassette 100 (S1401), and the transport roller 105 starts rotating. Also, the photosensitive drum 1
The timing for starting the exposure for forming a latent image on the image 12 is set (S1402). This timing is set after a lapse of time T4 from the paper feed start timing.

When the sheet feeding operation is started, the controller 12
A value of 0 determines whether the leading edge of the sheet has reached the determination sensor 109 based on the output of the determination sensor 109 (S1403). If the leading edge of the paper has not yet reached
It is determined whether the time T3, which is the delay limit time, has elapsed from the start of sheet feeding (S1404). If the time T3 has not elapsed, it is determined again whether the leading edge of the sheet has reached the determination sensor 109 (step S1404). S1403). If it is determined in step S1404 that the time T3 has already elapsed, it is determined that the interval between the next conveyed sheet is already gone and that the sheet is not in a state where the sheet can be conveyed normally. The conveyance is stopped, and the user is notified of the paper jam via a display screen (not shown) or the like (S1405).

If it is detected in step S1403 that the leading edge of the sheet has reached the determination sensor 109, the controller 120 determines that the delay control boundary time T2, which is the maximum limit time for which delay correction can be performed, has elapsed since the start of sheet feeding. It is determined whether or not it has been performed (S1406). If the time T2 has not elapsed yet, a delay time T "with respect to the reference time T0 is calculated and stored in the controller 120 (S1407). The time tA required to move to the position before is calculated, and based on this time tA, it is waited that the leading edge of the sheet reaches the pre-registration roller 107 (S1408).

The time tA (sec) is determined by the judgment sensor 10
Assuming that the distance between the roller 9 and the pre-registration roller 107 is X (mm) and the paper transport speed of the transport roller 105 is V (mm / sec), the following equation (17) is used.

TA = X / V (17) After the elapse of the time tA, it is considered that the leading edge of the sheet has arrived at the pre-registration roller 107.
0 controls the speed of the pre-registration roller 107 via the pre-registration motor drive circuit 107a (S1409). That is, the pre-registration roller 1 is controlled so that the time required when the sheet is conveyed from the pre-registration roller 107 to the registration sensor 108 is shorter than the normal paper conveyance time by the stored delay time T ″.
07 is performed.

Assuming that the increased transport speed of the pre-registration roller 107 is Z (mm / sec) and the distance from the pre-registration roller 107 to the registration sensor 108 is Y (mm), the delay time T ″ (sec) is as follows. It is represented by equation (18).

T ″ = Y / V−Y / Z (18) From this equation (18), the transport speed Z can be derived as in the following equation (19).

Z = 1 / (1 / VT− / Y) (19) That is, the transport speed of the pre-registration roller 107 is calculated by the above equation (1).
9), the sheet is conveyed at the conveying speed Z. With this, the delay sheet is also sent to the registration sensor 1 at the same timing that the reference sheet in the normal conveyance state would reach the registration sensor 108.
08 is reached.

If Z = 2V, for example, the following equation (20) is derived from the above equation (19).

T ″ = Y / 2V (20) Therefore, by setting the transport speed Z of the pre-registration roller 107 to twice the normal transport speed V (the same as the paper transport speed of the transport roller 105), , Y / 2V.

When the speed increasing control is started, it is confirmed whether or not T4, which is the time from the sheet feeding start timing to the exposure start timing, has elapsed, and the process waits until the time T4 has elapsed (S1410). When it is confirmed that the time T4 has elapsed, an enable signal is transmitted to the memory 208 to read out image information, and based on the image information,
Exposure to the photosensitive drum 112 is started via the laser modulator 111 (S1411).

By this delay control, as shown by the solid line in FIG. 12, the speed of the delayed sheet is increased from the point where it reaches the pre-registration roller 107, and the timing at which the leading edge of the reference sheet indicated by the dotted line reaches the registration sensor 108 is determined. At the same timing, the leading end of the sheet reaches the registration sensor 108.

When each sheet is delayed, by repeating this delay control for each sheet, the time t shown in FIG.
2 can be kept constant.

Further, the exposure start timing is set to a timing (feeding start) when the leading end of the reference sheet (shown by a dotted line) is located at a position (position A in FIG. 12) on the transport path which is a distance l ₁ from the transfer position 112a. (The timing after the lapse of the time T4), the exposure start timing is set irrespective of the sheet delay. Therefore, the image is transferred to a normal position with respect to the sheet, and there is no trouble such as too much margin at the leading or trailing edge of the sheet, or the leading or trailing edge of the image is cut off.

Next, a description will be given with reference to FIGS.

If the delay control boundary time T2 has elapsed in step S1406, the flow advances to step S1412 to calculate the maximum speed increase control time t4, which is the difference between the time T2 and the time T0, and further calculate the transport start time. , The time t5, which is the difference between the time required for the leading edge of the sheet to reach the determination sensor 109 and the time T2, is calculated.
Is stored in the controller 120. The time t5 is a time in which the roller 107 cannot be recovered even if the pre-registration roller 107 is controlled to the maximum speed.

Next, the controller 120 calculates a time tA required for the leading edge of the sheet to move from the determination sensor 109 to the pre-registration roller 107. Based on this time tA, the leading edge of the sheet reaches the pre-registration roller 107. Wait for that (S1413).

The time tA (sec) is determined by the judgment sensor 10
Assuming that the distance between the roller 9 and the pre-registration roller 107 is X (mm), and the paper transport speed of the transport roller 105 is V (mm / sec), the following equation (21) is used.

TA = X / V (21) After the elapse of the time tA, it is considered that the leading edge of the sheet has arrived at the pre-registration roller 107.
0 controls the maximum speed of the pre-registration roller 107 via the pre-registration motor drive circuit 107a (S1414). That is, the sheet is moved from the pre-registration roller 107 to the registration sensor 108.
The time required when the wafer was transported to
The pre-registration roller 107 is driven at an increased speed so as to reduce the normal paper conveyance time by four minutes.

Assuming that the increased transport speed of the pre-registration roller 107 is Z (mm / sec) and the distance from the pre-registration roller 107 to the registration sensor 108 is Y (mm), the delay time t4 (sec) is given by the following equation. It is represented by (22).

T4 = Y / V−Y / Z (22) From this equation (22), the transport speed Z can be derived as in the following equation (23).

Z = 1 / (1 / V−t4 / Y) (23) Since t4 = T2−T0, the equation (23) is expressed as the following equation (24).

Z = 1 / [1 / V− (T2−T0) / Y] (24) That is, the pre-registration roller 107 was driven at the maximum transport speed determined by the above equation (24) to delay. Try to transport the paper. As a result, the leading end of the delayed sheet reaches the registration sensor 108 with a delay of time t5 from the timing at which the reference sheet in the normal conveyance state would reach the registration sensor 108.

By this delay control, as shown by the solid line in FIG. 13, the delayed sheet is transported at the maximum possible transport speed from the point where it reaches the pre-registration roller 107, and the leading edge of the reference sheet shown by the dotted line is sent to the registration sensor 108. It arrives at the registration sensor 108 with a delay of time t5 from the arrival timing.

Therefore, the timing of turning on the resist CL106b is delayed by the time t5. Accordingly, the interval between the next sheet and the next sheet is reduced, so that the timing for feeding the next sheet is delayed by the time t5 (S1415).

By doing so, the time t2 shown in FIG.
Is (t2 + t5), but the image formation can be performed with the minimum delay amount t5 with respect to the time (t4 + t5) when the sheet is actually delayed.

By the way, if the exposure start timing is set after the elapse of time T4 from the paper feed start timing, the timing at which the leading edge of the paper arrives at the transfer position 112a due to the delay time t5 depends on the timing at which the leading edge of the image is exposed. Due to the rotation of the drum 112, the timing of arriving at the transfer position 112a is delayed by the time t5, and even if the transfer is performed as it is, the leading end image is missing. Therefore, the exposure start timing is reset (S1416). That is, the time t5 is added to the time T4 set at the start of sheet feeding in step S1402, and the time (T4 + t5) is reset to the time from the sheet feeding start timing to the exposure start timing.

Thereafter, in step S1410, it is confirmed whether or not the time (T4 + t5) has elapsed from the sheet feeding start timing. When it is confirmed that the time (T4 + t5) has elapsed, the memory 208 is enabled. A signal is transmitted to read out image information, and exposure to the photosensitive drum 112 is started via the laser modulator 111 based on the image information (S1411).

Thus, even if the image formation is delayed as described above, the image forming apparatus is stopped due to a paper jam or the like, and the productivity is significantly reduced or the printing is significantly reduced. Compared with outputting an unsightly image with inferior accuracy and forcing the user to perform the copying operation again, the present invention can improve productivity much higher.

Even if a delay occurs in the formation of an analogous image as described above, the time from the sheet supply start timing to the exposure start timing is extended by the irreversible delay (time t5) of the sheet conveyance, whereby the sheet Chipping of the image transferred to the image can be prevented.

A storage medium storing program codes of software for realizing the functions of the above-described embodiments is supplied to a system or an apparatus, and a computer (or CPU or MPU) of the system or the apparatus stores the storage medium in the storage medium. It goes without saying that the present invention is also achieved by reading and executing the stored program code.

In this case, the program code itself read from the storage medium realizes the functions of the above embodiments, and the storage medium storing the program code constitutes the present invention. .

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also an OS running on the computer based on the instructions of the program code. Performs some or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.
Needless to say, this is included in the present invention.

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, based on the instruction of the program code, It is needless to say that the present invention includes a case where the CPU or the like provided in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments. No.

[0138]

As described above in detail, according to the present invention, paper feeding means for separating and feeding a plurality of papers one by one, and variable conveyance independent of the paper feeding speed of the paper feeding means. Transport means for transporting the paper fed by the paper feeding means, a registration means for correcting skew of the paper transported by the transport means, and a paper from the paper feeding means to the registration means; A sheet detecting unit that is disposed in a conveying path and detects a sheet fed by the sheet feeding unit, wherein a speed determining unit detects the sheet based on a sheet detection timing at which the sheet detecting unit detects the sheet. Determine the transport speed of the means.

Thus, the interval between sheets can be further reduced with a simple configuration, no jam occurs, and high productivity can be efficiently achieved while ensuring high printing accuracy even at the same process speed. Can be improved.

Further, even if the paper interval greatly varies due to slippage of the paper at the time of transporting the paper or variation in the posture (position) of the paper in the paper storage cassette,
An output image with extremely high printing accuracy can be obtained, and occurrence of jam can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of an image forming apparatus.

FIG. 3 is a timing chart showing a state in which a sheet sent from a cassette is transported in a normal state.

FIG. 4 is a diagram illustrating a sheet conveyance timing when early arrival occurs.

FIG. 5 is a flowchart illustrating a procedure of a process performed by a controller when an early arrival occurs.

FIG. 6 is a diagram illustrating a sheet conveyance timing when a correctable delay occurs.

FIG. 7 is a diagram illustrating a sheet conveyance timing when an uncorrectable delay occurs.

FIG. 8 is a flowchart illustrating a procedure of processing performed by a controller when a delay occurs.

FIG. 9 is a timing chart showing a state in which a sheet sent from a cassette is transported in a normal state in the second embodiment.

FIG. 10 is a diagram showing a sheet conveyance timing when an early arrival occurs in the second embodiment.

FIG. 11 is a flowchart illustrating a procedure of a process performed by a controller when an early arrival occurs according to the second embodiment.

FIG. 12 is a diagram illustrating a sheet conveyance timing when a correctable delay occurs in the second embodiment.

FIG. 13 is a diagram illustrating a sheet conveyance timing when an uncorrectable delay occurs in the second embodiment.

FIG. 14 is a flowchart illustrating a procedure of processing performed by a controller when a delay occurs according to the second embodiment;

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Upper cassette 101 Paper feed roller (paper feed means) 102 Lower paper cassette 103 Paper feed roller (paper feed means) 104 Transport roller (paper feed means) 105 Transport roller (paper feed means) 106 Registration roller (register means) 107 Before registration Roller (conveying means) 108 Registration sensor (registering means) 109 Judgment sensor (paper detecting means) 111 Laser modulator (image forming means) 112 Photosensitive drum (image carrier) 120 Controller (speed determining means) 206 Image processing unit 208 Memory (Storage device) 1000 Printer (image forming device) 2000 Scanner

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H072 AA02 AA07 AA13 AA16 AA22 AA29 AB09 AB27 BA03 BA13 BA16 BA20 CA01 EA01 HB09 JA02 3F049 AA01 DA12 DB11 EA12 EA24 EA28 LA01 LB01 3F102 AA01 AB01 EB02 CB02 FA03

Claims (33)

[Claims] 1. An image forming apparatus capable of forming the same image on a plurality of sheets based on image information stored in a storage device, wherein a plurality of sheets are separated and fed one by one. A transport unit that has a variable transport speed independent of the paper feed speed of the paper feed unit, and transports the paper fed by the paper feed unit; and skew correction of the paper transported by the transport device. Registering means for detecting the sheet fed from the sheet feeding means to the registering means, and detecting the sheet fed by the sheet feeding means; and detecting the sheet by the sheet detecting means. And a speed determining means for determining a transport speed of the transport means based on the detected sheet detection timing. 2. The image forming apparatus according to claim 1, further comprising: a rotating image carrier; and an image forming unit configured to form an image on a rotating surface of the image carrier, wherein the registration unit controls movement of the sheet transported by the transport unit. 4. The method according to claim 1, wherein the sheet is temporarily stopped, and the conveyance of the sheet is resumed at a timing such that the image formed on the image carrier by the image forming unit is transferred to a predetermined position on the sheet. 2. The image forming apparatus according to 1. 3. The method according to claim 2, wherein the speed determining unit detects a time difference between the sheet detection timing and a predetermined timing, and the conveying unit according to the time difference detected by the time difference detecting unit. When the paper is conveyed at the same speed as the paper feeding speed of the paper feeding means, the conveying means such that the paper reaches the registration means at the same timing as the paper reaches the registration means. The image forming apparatus according to claim 1, further comprising: a determination unit configured to determine a transport speed of the image. 4. The method according to claim 1, wherein the determining unit determines that the transport speed of the transport unit is lower than the paper feed speed of the paper feed unit when the paper detection timing is earlier than the predetermined timing. The image forming apparatus according to claim 3, wherein: 5. When the paper detection timing is later than the predetermined timing, the determination unit determines the transport speed of the transport unit to be higher than the paper feed speed of the paper feed unit. The image forming apparatus according to claim 3, wherein: 6. The method according to claim 1, wherein the speed determining unit determines that the sheet detection timing is after the first predetermined timing and before the second predetermined timing. A time difference detecting means for detecting a time difference from the timing; and, in accordance with the time difference detected by the time difference detecting means, the conveying means conveys the sheet at the same speed as the sheet feeding speed of the sheet feeding means. In this case, the transport speed of the transport unit is determined to be faster than the paper feed speed of the paper feed unit so that the paper arrives at the register unit at the same timing as the paper arrives at the register unit. The first predetermined timing is a timing at which paper is to be detected by the paper detection unit when the paper is normally fed, and the second predetermined timer is The transporting of the sheet at the maximum possible transport speed of the transport unit allows the sheet to be transferred to the registration unit when the transport unit transports the sheet at the same speed as the feed speed of the paper feed unit. 2. The image forming apparatus according to claim 1, wherein the timing is a maximum delay timing at which the sheet can reach the registration unit at the same timing as the timing at which the sheet arrives. 7. The method according to claim 6, wherein the speed determining unit determines that the sheet detection timing is equal to or shorter than the first predetermined timing and is earlier than the second predetermined timing. A time difference detecting means for detecting a time difference from the timing; and, in accordance with the time difference detected by the time difference detecting means, the conveying means conveys the sheet at the same speed as the sheet feeding speed of the sheet feeding means. In this case, the transport speed of the transport unit is determined to be faster than the paper feed speed of the paper feed unit so that the paper arrives at the register unit at the same timing as the paper arrives at the register unit. The first predetermined timing is a timing at which paper is to be detected by the paper detection unit when the paper is normally fed, and the second predetermined timer is The transporting of the sheet at the maximum possible transport speed of the transport unit allows the sheet to be transferred to the registration unit when the transport unit transports the sheet at the same speed as the feed speed of the paper feed unit. 3. The image forming apparatus according to claim 2, wherein the timing is a maximum delay timing at which the sheet can reach the registration unit at the same timing as the timing at which the sheet arrives. 8. When the paper detection timing is later than the second predetermined timing, the speed determination unit determines the transport speed of the transport unit to be the maximum possible transport speed, and 8. The image forming apparatus according to claim 7, further comprising a conveyance restart delay unit that delays a conveyance restart timing of the sheet by the registration unit by a difference from the second predetermined timing. 9. A paper feed delay means for delaying the paper feed timing of the next paper by the paper feed means by a difference between the paper detection timing and the second predetermined timing. The image forming apparatus as described in the above. 10. The image forming apparatus according to claim 8, further comprising image forming delay means for delaying an image forming timing by said image forming means by a difference between said sheet detection timing and said second predetermined timing. The image forming apparatus as described in the above. 11. The image forming apparatus according to claim 2, wherein an image forming timing by said image forming means is earlier than a timing of resuming conveyance of said sheet by said registration means. apparatus. 12. A paper feeding means for separating a plurality of papers one by one and feeding the paper, a variable conveyance speed independent of a paper feeding speed of the paper feeding means, and a paper fed by the paper feeding means. Transport means for transporting the fed paper, resist means for correcting skew of the paper transported by the transport means, and a paper transport path arranged from the paper feed means to the resist means. A sheet detecting means for detecting a fed sheet, and determining a transport speed applied to an image forming apparatus capable of forming the same image on a plurality of sheets based on image information stored in a storage device In the method, a sheet detection step in which the sheet detection unit detects a sheet fed by the sheet feeding unit, and a conveyance of the conveyance unit based on a sheet detection timing at which the sheet detection unit detects the sheet. Conveying speed determination method characterized by having a rate determining step of determining a degree. 13. The image forming apparatus further comprises: a rotating image carrier; and an image forming unit for forming an image on a rotating surface of the image carrier, wherein the registration unit is transported by the transport unit. A function of temporarily stopping the movement of the sheet, and restarting the conveyance of the sheet at a timing such that the image formed on the image carrier by the image forming unit is transferred to a predetermined position of the sheet. The method according to claim 12, further comprising: 14. The speed deciding step, wherein: a difference time detecting step for detecting a time difference between the sheet detection timing and a predetermined timing; and the conveying means according to the time difference detected by the time difference detecting step. When the paper is conveyed at the same speed as the paper feeding speed of the paper feeding means, the conveying means such that the paper reaches the registration means at the same timing as the paper reaches the registration means. 14. The method according to claim 12, further comprising the step of: determining the transport speed. 15. The determining step, when the sheet detection timing is earlier than the predetermined timing, determines a transport speed of the transport unit to be lower than a paper feed speed of the paper feed unit. 15. The method according to claim 14, wherein
The transport speed determination method described in the above. 16. The determining step, when the sheet detection timing is later than the predetermined timing, determining a transport speed of the transport unit to be higher than a paper feed speed of the paper feed unit. 15. The method according to claim 14, wherein
The transport speed determination method described in the above. 17. The method according to claim 17, wherein the step of determining the speed includes: when the sheet detection timing is later than a first predetermined timing and before a second predetermined timing, the sheet detection timing and the first predetermined timing are set. A difference time detection step of detecting a difference time from the timing; and, in accordance with the difference time detected by the difference time detection step, the conveyance unit conveys the sheet at the same speed as the sheet feeding speed of the sheet feeding unit. In this case, the transport speed of the transport unit is determined to be faster than the paper feed speed of the paper feed unit so that the paper arrives at the register unit at the same timing as the paper arrives at the register unit. Determining that the first predetermined timing is a timing at which a sheet is to be detected by the sheet detecting means when the sheet feeding is normal, The second predetermined timing is such that the sheet is conveyed at the maximum possible conveyance speed of the conveyance unit, and the conveyance unit conveys the sheet at the same speed as the paper supply speed of the paper supply unit. 13. The method according to claim 12, wherein the maximum delay timing is such that the sheet can reach the registration unit at the same timing as the sheet reaches the registration unit. 18. The method according to claim 18, wherein the sheet detection timing is after the first predetermined timing and before the second predetermined timing. A difference time detection step of detecting a difference time from the timing; and, in accordance with the difference time detected by the difference time detection step, the conveyance unit conveys the sheet at the same speed as the sheet feeding speed of the sheet feeding unit. In this case, the transport speed of the transport unit is determined to be faster than the paper feed speed of the paper feed unit so that the paper arrives at the register unit at the same timing as the paper arrives at the register unit. Determining that the first predetermined timing is a timing at which a sheet is to be detected by the sheet detecting means when the sheet feeding is normal, The second predetermined timing is such that the sheet is conveyed at the maximum possible conveyance speed of the conveyance unit, and the conveyance unit conveys the sheet at the same speed as the paper supply speed of the paper supply unit. 14. The transport speed determining method according to claim 13, wherein the maximum delay timing is such that the sheet can reach the registration unit at the same timing as the sheet reaches the registration unit. 19. The speed determining step, when the paper detection timing is later than the second predetermined timing, determines the transport speed of the transport unit to the maximum possible transport speed, and 19. The transport speed determining method according to claim 18, further comprising a transport restart delay step of delaying the transport restart timing of the sheet by the registration unit by a difference from the second predetermined timing. 20. A paper feed delay step for delaying the paper feed timing of the next paper by the paper feed means by a difference between the paper detection timing and the second predetermined timing. The transport speed determination method described in the above. 21. An image forming apparatus according to claim 19, further comprising an image forming delay step of delaying an image forming timing by said image forming means by a difference between said sheet detection timing and said second predetermined timing. The transport speed determination method described in the above. 22. The transport speed according to claim 13, wherein an image forming timing by the image forming unit is earlier than a transport restart timing of the sheet by the registration unit. Decision method. 23. A sheet feeding means for separating and feeding a plurality of sheets one by one, and a variable conveying speed independent of the feeding speed of the sheet feeding means, wherein the sheet is fed by the sheet feeding means. Transport means for transporting the fed paper, resist means for correcting skew of the paper transported by the transport means, and a paper transport path arranged from the paper feed means to the resist means. A sheet detecting means for detecting a fed sheet, and determining a transport speed applied to an image forming apparatus capable of forming the same image on a plurality of sheets based on image information stored in a storage device In a computer-readable storage medium storing a method as a program, the transport speed determining method includes detecting a sheet fed by the sheet feeding unit by the sheet detecting unit. Step a, the sheet detecting means storage medium characterized by having a rate determining step of determining a conveying speed of said conveying means based on a sheet detection timing of detecting the paper. 24. The image forming apparatus further comprises: a rotating image carrier; and an image forming unit for forming an image on a rotating surface of the image carrier, wherein the registration unit is transported by the transport unit. A function of temporarily stopping the movement of the sheet, and restarting the conveyance of the sheet at a timing such that the image formed on the image carrier by the image forming unit is transferred to a predetermined position of the sheet. The storage medium according to claim 23, comprising: 25. The speed determining step, wherein: the difference detecting step detects a time difference between the sheet detection timing and a predetermined timing; and the conveying means according to the difference detected by the difference detecting step. When the paper is conveyed at the same speed as the paper feeding speed of the paper feeding means, the conveying means such that the paper reaches the registration means at the same timing as the paper reaches the registration means. 25. The storage medium according to claim 23, further comprising a determining step of determining a transport speed of the recording medium. 26. The determining step, when the paper detection timing is earlier than the predetermined timing, determining the transport speed of the transport unit to be lower than the paper feed speed of the paper feed unit. 25. The method according to claim 25, wherein
The storage medium according to the above. 27. The determining step, when the paper detection timing is later than the predetermined timing, determines a transport speed of the transport unit to be higher than a paper feed speed of the paper feed unit. 25. The method according to claim 25, wherein
The storage medium according to the above. 28. The method according to claim 28, wherein the sheet detection timing and the first predetermined time are determined when the sheet detection timing is later than a first predetermined timing and before a second predetermined timing. A difference time detection step of detecting a difference time from the timing; and, in accordance with the difference time detected by the difference time detection step, the conveyance unit conveys the sheet at the same speed as the sheet feeding speed of the sheet feeding unit. In this case, the transport speed of the transport unit is determined to be faster than the paper feed speed of the paper feed unit so that the paper arrives at the register unit at the same timing as the paper arrives at the register unit. Determining that the first predetermined timing is a timing at which a sheet is to be detected by the sheet detecting means when the sheet feeding is normal, The second predetermined timing is such that the sheet is conveyed at the maximum possible conveyance speed of the conveyance unit, and the conveyance unit conveys the sheet at the same speed as the paper supply speed of the paper supply unit. 24. The storage medium according to claim 23, wherein the maximum delay timing is such that the sheet can reach the registration unit at the same timing as the sheet reaches the registration unit. 29. The speed determination step, wherein the sheet detection timing and the first predetermined timing are set when the paper detection timing is later than a first predetermined timing and before a second predetermined timing. A difference time detection step of detecting a difference time from the timing; and, in accordance with the difference time detected by the difference time detection step, the conveyance unit conveys the sheet at the same speed as the sheet feeding speed of the sheet feeding unit. In this case, the transport speed of the transport unit is determined to be faster than the paper feed speed of the paper feed unit so that the paper arrives at the register unit at the same timing as the paper arrives at the register unit. Determining that the first predetermined timing is a timing at which a sheet is to be detected by the sheet detecting means when the sheet feeding is normal, The second predetermined timing is such that the sheet is conveyed at the maximum possible conveyance speed of the conveyance unit, and the conveyance unit conveys the sheet at the same speed as the paper supply speed of the paper supply unit. 25. The storage medium according to claim 24, wherein the maximum delay timing is such that the sheet can reach the registration unit at the same timing as the sheet reaches the registration unit. 30. The method according to claim 30, wherein, if the sheet detection timing is later than the second predetermined timing, the transport speed of the transport unit is determined to be the maximum possible transport speed. 30. The storage medium according to claim 29, further comprising a transport restart delay step of delaying the transport restart timing of the paper by the registration unit by a difference between the paper detection timing and the second predetermined timing. 31. The method according to claim 31, wherein the transport speed determining method further includes a paper feed delay step of delaying a paper feed timing of the next paper by the paper feed unit by a difference between the paper detection timing and the second predetermined timing. 31. The storage medium according to claim 30, wherein: 32. The method according to claim 31, further comprising an image forming delay step of delaying an image forming timing by the image forming unit by a difference between the sheet detection timing and the second predetermined timing. The storage medium according to claim 30 or claim 31. 33. The storage medium according to claim 24, wherein an image forming timing by said image forming means is earlier than a timing at which the registration means conveys the sheet again. .