JP2000198575A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form proper images while correcting sheet obliquity and ensuring sheet head margins even when sheets are fed at no intervals or with slight overlaps. SOLUTION: A separating mechanism comprises two guide members 17 and 18 defining a feed path 40, one guide member 18 having a swell, a first feeding means 2 for delivering sheets into the feed path 40, and a second feeding means 5 for delivering the sheets in the feed path 40 to an image forming part. A leading sheet P fed along the swell of the guide member 18 after delivered into the feed path 40 is next fed along the other guide member 17 at preset timing to form no sheet intervals. The leading edge of a succeeding sheet Pa regularly overlapping with the trailing edge of the leading sheet P while being fed is alternatively separated from the trailing edge of the leading sheet P once within the feed path 40. The leading edge of the succeeding sheet Pa thus separated is detected by a leading edge detecting means 3.

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, and more particularly, to a method in which a sheet is conveyed to an image forming section in a state where a distance between the sheets (hereinafter, referred to as a sheet distance) is 0 or a sheet is slightly overlapped. , Which perform image formation.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus for forming an image by feeding a recording sheet, which has been previously cut to a fixed size called a cut sheet, to an image forming section, the recording sheet is formed at predetermined sheet intervals. The paper is fed to the department.

Here, in order to maximize the effective use of the process speed, it is desirable to feed, convey, and form an image with a sheet interval of 0 or slightly overlapping the recording sheet.

[0004]

However, in the conventional image forming apparatus, when an image is formed at a sheet interval of 0, detection of the leading edge of the recording sheet is a problem. That is, for example, when a recording sheet is conveyed at a sheet interval of 0, the leading edge of the leading recording sheet can be detected by the conventional leading edge detecting means, but it is difficult to detect the leading edges of the second and subsequent recording sheets.

Here, if the leading edge of each recording sheet cannot be detected, it is difficult to accurately form an image in a predetermined image area of each recording sheet. Specifically, if the leading edge cannot be detected accurately, it becomes difficult to take a register, which affects the skew correction of the recording sheet.
Also, it becomes difficult to secure the margin at the tip.

Accordingly, the present invention has been made in view of such a situation. Even when a sheet is conveyed with the sheet interval being 0 or slightly overlapping, the skew correction and the margin of the leading end can be ensured. It is another object of the present invention to provide an image forming apparatus capable of forming an appropriate image.

[0007]

According to the present invention, there is provided an image forming section, a sheet storing section for storing sheets, and a conveying path for conveying the sheets stored in the sheet storing section toward the image forming section. An image forming apparatus, wherein the sheet interval of the sheet is set to 0 in the conveyance path, or the leading end of the next sheet is made to enter the rear end of the preceding sheet by overlapping by a predetermined amount, 0, or a separation mechanism that once separates the leading edge of the next sheet that has entered the transport path with a predetermined amount of overlap with the preceding sheet from the trailing edge of the preceding sheet in the transport path; And a leading edge detecting means for detecting a leading edge of the next sheet separated by the mechanism.

In the present invention, the separation mechanism may include two guide members opposing each other, which form the conveyance path and have a bulging portion formed on one side, and enter the sheet stored in the sheet storage section into the conveyance path. And a second conveying means for conveying the sheet that has entered the conveying path toward the image forming unit, and conveys the preceding sheet that has entered the conveying path along the bulging portion. After that, the leading edge of the next sheet is separated from the trailing edge of the preceding sheet by being conveyed along the other of the two opposing guide members at a predetermined timing. Is what you do.

Further, according to the present invention, the sheet conveying speed of the second conveying means is set such that the preceding sheet conveyed along the bulging portion is conveyed along the other of the two opposing guide members. In this case, the speed is higher than the sheet conveying speed of the means.

Further, the present invention is characterized in that the leading end detecting means is configured not to detect a preceding sheet conveyed along the other of the two guide members.

Further, according to the present invention, the leading sheet abuts on the downstream side of the conveyance path along the bulging portion to bend along the bulging portion, and the skew of the leading sheet is skewed. The skew correction member for correcting the skew is provided so as to be able to advance and retreat.

Further, according to the present invention, the other of the two guide members forming the transport path is formed in a substantially straight line, and the sheet transport direction of the first transport means is set to one of the two guide members having the bulging portion. In a direction along the line.

Further, as in the present invention, two opposing guide members forming a conveying path and having a bulging portion formed on one side, and a first conveying means for causing the sheets stored in the sheet storing section to enter the conveying path. And a separation mechanism including a second conveyance unit that conveys the sheet that has entered the conveyance path toward the image forming unit. The sheet is conveyed along the other of the two guide members at the timing to set the sheet interval to 0, or once to convey the leading edge of the next sheet which has entered the rear end portion of the preceding sheet P by overlapping the leading end by a predetermined amount. Separate from the trailing edge of the preceding sheet in the road. Then, the leading edge of the next sheet separated by the separating mechanism is detected by the leading edge detecting means.

[0014]

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

FIG. 1 is a diagram showing a configuration of an image forming apparatus according to a first embodiment of the present invention.
Denotes an image forming apparatus, and 101 denotes an image forming apparatus main body (hereinafter, referred to as main body).

In this image forming apparatus 100, after a recording sheet P on which an image is to be formed is fed from a sheet feeding cassette 1 serving as a sheet storing means, a vertical path roller 2 serving as a first conveying means and a second conveying means After the registration, the rollers 5 pass through the transport path 40, and then are stacked on the transport belt 6 and transported to the image forming unit 50.

Further, the image forming apparatus 100 includes four electrophotographic photosensitive drums 7 serving as image forming means in response to image information signals transmitted from a reader scanner, a personal computer or the like (not shown) in the image forming section 50. The toner images formed on the surfaces of 8, 9, and 10 are
After being sequentially transferred to the recording sheet P, the recording sheet P is permanently fixed by the fixing device 15, and thereafter, the recording sheet P on which a monochrome or full-color image is formed is discharged onto the discharge tray 16.

It should be noted that, in FIG.
An LED (light emitting diode) 14 is independently controlled as a light source device for forming a toner image on the surface of each of the photosensitive drums 7, 8, 9, and 10.
1, 12, 13, and 14 are configured to face the respective surfaces of the photosensitive drums 7, 8, 9, and 10.

On the other hand, the image forming apparatus 100 is provided with an automatic double-sided function. When images are formed on both sides of the sheet material P, the recording sheet P having an image formed on one side is transferred to the main body 1.
After passing through the double-sided pass unit 30 provided in the image forming unit 01, the sheet is conveyed to the image forming unit 50 again to form an image on the back surface.

In the image forming apparatus 100, in order to make the most effective use of the process speed in the image forming section 50, in the continuous recording mode, each recording sheet P stacked on the transport belt 6 has a sheet interval. 0, rather, the recording sheet is conveyed and formed with an overlap in a very small portion.

Next, the detection of the leading edge of the recording sheet P when the recording sheet P is conveyed while being overlapped will be described with reference to FIG.

In FIG. 1, reference numeral 17 denotes a lower guide, and reference numeral 18 denotes an upper guide which forms a transport path 40 together with the lower guide 17. The upper and lower guides 17 and 18 together with the above-described vertical path roller 2 and the post-registration roller 5 move the leading end of the next recording sheet that has overlapped with the preceding recording sheet once in the transport path. This constitutes a separation mechanism for separating the sheet from the rear end.

Reference numeral 4 denotes a registration removing member which is a skew correcting member provided to be able to advance and retreat in the transport path 40. When the recording sheet P is transported, the registration removing member 4
When the recording sheet P is conveyed from the vertical path roller 2 and abutted against the leading edge of the recording sheet P, the recording sheet P is registered.

Here, this registration is performed by the registration removing member 4.
The upper guide 18 is moved to the lower guide 17 so that the loop of the recording sheet P can be formed by abutting the leading end of the recording sheet P against the recording sheet P.
And a loop space S which is a bulging portion is formed.

On the other hand, after the registration is performed in this manner,
When the registration member 4 withdraws from the conveyance path 40 at a predetermined timing, the recording sheet P elastically enters the nip N of the pair of rollers 5 after registration, and when the roller pair 5 rotates after registration, the recording sheet P P is transported to the image forming unit 50 in a state where the skew is corrected.

The length of the recording sheet P in the transport direction is as follows:
The length of the recording sheet P is longer than the distance between the vertical pass roller 2 and the pair of post-registration rollers 5, so that the recording sheet P is not moved until the rear end of the recording sheet P passes through the vertical pass roller 2. The pair 5 is transported.

In this embodiment, when the sheet conveying speed of the vertical path roller 2 is V ₁ and the sheet conveying speed of the pair of rollers 5 after registration is V ₂ , each conveying speed is set so that the following relationship is established. V ₁ and V ₂ are set.

V ₁ ≦ V ₂ ... By setting the respective conveying speeds V ₁ and V ₂ to have such a relationship, after performing registration, the vertical pass roller 2 and the pair of rollers 5 after registration are removed. When the recording sheet P is being conveyed, the slack of the recording sheet P is not formed as much as possible in the loop space S. In other words, the loop formed on the recording sheet P for the registration is removed in the conveyance after the registration is removed. So that it can be absorbed.

On the other hand, in FIG. 3, reference numeral 3a denotes a sensor arm rotatably provided in the loop space S. The sensor arm 3a is pressed by the leading end of the recording sheet P conveyed by the vertical path roller 2. It is designed to rotate.

When the sensor arm 3a rotates as described above, the photo interrupter 3b constituting the tip detecting sensor 3 as the tip detecting means shown in FIG. 3 is turned on together with the sensor arm 3a, and the ON signal of the photo interrupter 3b is turned on. The control device 35 shown in FIG. 3 detects that the leading end of the recording sheet P has passed.

Further, based on the detection of the leading end, the controller 35 retreats the registration-removing member 4 that has performed the registration from the conveyance path 40 at a predetermined timing, and moves the pair of rollers 5 and the vertical path roller 2 after the registration is removed. Drive at the speed of the relationship.

The sensor arm 3a is connected to the recording sheet P
When pressed by the leading edge of the recording sheet P, the recording sheet P can be sufficiently retracted so as not to hinder the conveyance, and when the recording sheet P is released from the pressure, it returns to its original state by itself.

By the way, the leading end detection sensor 3 is configured not to detect the recording sheet P when the recording sheet P is conveyed while being sandwiched between the sensor arm 3a and the lower guide 17. . That is, as shown in FIG. 4, the recording sheet P in which the loop has been absorbed moves along the lower guide 17, and the distance L between the sensor arm 3a and the lower guide 17 becomes (one recording sheet equivalent). Thickness) +
The photointerrupter 3b is turned off when it becomes shorter than (predetermined minute amount).

That is, the leading edge detecting sensor 3 is once pressed by the leading edge of the recording sheet P, and outputs the leading edge detecting signal of the recording sheet P by rotating the sensor arm 3a to the position shown by the two-dot chain line in FIG. When the recording sheet P with the loop absorbed moves along the lower guide 17 and the sensor arm 3a rotates downward to the position shown by the dotted line, the output of the leading edge detection signal is stopped. It has become.

As described above, the region where the tip detection sensor 3 stops outputting the tip detection signal, that is, the tip detection sensor 3
In FIG. 4, an area in which the recording sheet P is not detected is indicated by H, and is hereinafter referred to as a non-detection area.

Thus, the control device 35 can detect only the passage of the leading edge of the recording sheet P based on the leading edge detection signal from the leading edge detection sensor 3.
The control device 35 controls the image forming unit 50 based on the OFF signal after the ON signal from the photo-interrupter 3b to sequentially perform image formation.

On the other hand, when the trailing end of the recording sheet P approaches the curved portion 41 of the transport path 40, the next recording sheet entering the transport path 40 in a state of being overlapped by the recording sheet P (hereinafter referred to as the next sheet). The leading end of the recording sheet Pa (referred to as a recording sheet) separates from the trailing end of the recording sheet P, and eventually presses the sensor arm 3a in contact with the recording sheet P as shown in FIG.

As a result, the sensor arm 3a pivots upward again, and the photointerrupter 3b is turned on with the upward pivoting of the sensor arm 3a.
Reference numeral 5 is for detecting the leading edge of the next recording sheet Pa.

Next, a description will be given of a leading end detecting operation of the image forming apparatus provided with the leading end detecting sensor 3 configured as described above.

When image formation in the continuous recording mode is set and a start command is issued, the control device 35 feeds the recording sheets P from the paper feed cassette 1. Here, when the paper feed pickup operation for the next recording sheet P ₂ is performed while the recording sheet P ₁ of the first sheet is not completely escape the paper feed cassette 1, thereby the two recording sheets P _{1 ,}
P ₂ is overlap.

In this overlap, the same number of sheets of the set number are fed. Also, this overlap amount is
After being registered by the registration member 4 immediately before being sent to the image forming unit 50, the conveying belt 6 of the image forming unit 50 is used.
It is preferable that the sheets are stacked with no sheet interval above them, or stacked so that only the blank portions (areas where image formation is not performed) of the recording sheets P overlap.

Next, the leading end portion of the _first recording sheet P1 fed in an overlapped state enters the transport path 40 by the vertical path roller 2, and as shown in FIG. It passes along the upper guide 18. That is, the leading end of the _first recording sheet P1 passes through a region above the non-detection region H of the leading end detection sensor 3 (see FIG. 4).

Next, the recording sheet P ₁ is transferred to the upper guide 18.
And then presses the sensor arm 3a, thereby rotating the sensor arm 3a as shown in FIG. 6 (b), thereby turning on the photo interrupter 3b and turning on the photo interrupter 3b. based on the signal, the control unit 35 based on the timing of detecting with detecting the leading edge of the recording sheet P _1, performs the registration removal operation already described.

On the other hand, after the registration is completed, the pair of rollers 5 after registration is driven together with the vertical pass roller 2. Note that the two rollers 2,5, when the two rollers 2,5 is conveying the recording sheet P ₁ is the second sheet conveyed overlapping recording sheet P ₂ is the leading edge detection The first recording sheet P1 is conveyed at such a speed difference that the _first recording sheet P1 does not become slack before reaching the vicinity of the sensor. Since this is based on the setting of the above equation, detailed description will be omitted.

When the slack of the _first recording sheet P ₁ is eliminated, the first recording sheet P ₁ is moved along the lower guide 17 as shown in FIG. In other words, the sensor arm 3a is conveyed along the non-detection area, and the sensor arm 3a rotates downward, and the tip detection sensor 3 outputs an OFF signal to the control device 35. Incidentally, when the OFF signal from such a leading edge detection sensor 3 is outputted, the control unit 35 starts the operation of the image forming unit 50 starts image formation on the recording sheet P _1.

Next, when the first recording sheet P ₁ is further conveyed, the second recording sheet P ₂ enters the conveyance path 40 soon. And this recording sheet P
₂ is conveyed along the upper guide 18, and when the sensor arm 3a is pressed by the tip at a point in time, the sensor arm 3a is consequently pressed.
The control device 35 detects the leading end of the _second recording sheet P2 based on the rotation of the sensor arm 3a as shown in FIG.

That is, the first recording sheet P ₁ passes without being detected by the photo-interrupter 3b except for the vicinity of the leading end, and the leading end detection sensor 3 sends the second recording sheet P Detect the tip of ₂ . Then, based on the detected timing, the control device 35 performs registration with respect to the _second recording sheet P2 and forms an image.
The leading edge of the third and subsequent recording sheets P is also detected by repeating this operation.

As described above, after the preceding recording sheet P ₁ that has entered the conveyance path 40 is conveyed along the upper guide 18,
The next recording sheet P ₂ , which is moved along the lower guide 17 and conveyed while overlapping the preceding recording sheet P _1.
Tip, once by separating from the rear end of the preceding recording sheet P ₁ in the conveying path, it is possible to reliably detect the leading end of the next recording sheet P ₂ of.

[0049] By thus reliably detects the leading edge of the next recording sheet P _2, even when conveying the recording sheet while the sheet interval 0 or overlapping slightly skew correction and edge margin As a result, appropriate image formation becomes possible.

In the above description, the detection of the leading end of the recording sheet P in the loop space S provided for the registration in the transport path 40 constituted by the guides 17 and 18 having a curvature will be described. However, the present embodiment is not limited to this.

For example, the intermediate tray 31 as shown in FIG.
In the image forming apparatus 100 provided with a paper feed unit, a portion joining from the re-feeding unit 32 to the feed vertical path 33 is constituted by guides 34a and 34b having a curvature, and the paper path unit 3 for changing the transport direction is provided.
Even in the case of No. 4, there is no problem even if the leading end of the recording sheet P is detected by the same means as described above, and the present invention can be widely applied not only to an image forming apparatus but also to any apparatus having a means for conveying a recording sheet such as an application.

In the first embodiment described above, the leading end of the next recording sheet is made to be farther from the preceding recording sheet in the direction of the leading end detection sensor in the transport path 40 configured to change the transport direction. Thus, the leading edge of the recording sheet can be detected.

However, when various image forming apparatuses are considered, it may be necessary to detect the leading edge of the recording sheet at a portion where the recording sheet is transported straight, such as a horizontal paper path or a vertical paper path.

Next, an image forming apparatus according to a second embodiment of the present invention corresponding to such a case will be described.

FIG. 9 is a diagram showing a configuration of the image forming apparatus according to the present embodiment. In the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts.

In the figure, 1A is an upper paper feed cassette,
Reference numeral 1B denotes a lower paper feed cassette disposed below the upper paper feed cassette 1A. Reference numeral 41 denotes a vertical path portion which is a transport path for directing the recording sheet P of the lower paper feed cassette 1B to the transport path 40. . Further, reference numeral 23 denotes an upstream conveying roller which is a first conveying means for conveying the recording sheet P of the lower sheet feeding cassette 1B to the vertical path unit 41, and reference numeral 25 denotes a conveying path 40 for conveying the recording sheet P conveyed to the vertical path unit 41. A downstream transport roller that is a second transport unit that is directed to the image forming unit 50 via the image forming unit 50.

Here, this vertical path section 41 is
Is curved so that the transport direction of the recording sheet P can be changed, whereas it is configured substantially linearly so as not to change the transport direction. That is, as shown in FIG. 10, the vertical path portion 41 includes an inner guide 26 extending substantially linearly in the direction of the transport path 40 and an outer guide 27 having a bulging portion bulging outward. It is.

In this embodiment, the direction of the nip N of the downstream transport roller 25 is substantially parallel to the inner guide 26 (parallel to the transport direction of the entire portion), whereas the upstream transport roller 25 is parallel. 23 Nip N is outer guide 2
7 in the bulging direction. Thus, the recording sheet P of the lower sheet cassette 1 </ b> B that has entered the vertical path section 41 by the upstream conveyance roller 23 is directed to the downstream roller 25 along the outer guide 27.

Further, on the outer guide 27 side, there is provided a tip detection sensor 24 composed of a sensor arm 24a and a photo interrupter 24b. here,
When the recording sheet P passes through a non-detection area between the sensor arm 24a and the inner guide 26, the leading end detection sensor 24 is similar to the first embodiment described above.
Is not detected.

In this embodiment, when the sheet transport speed of the upstream transport roller 23 is V ₃ and the sheet transport speed of the downstream transport roller 25 is V ₄ , each transport is performed so that the following relationship is established. The speeds V ₃ and V ₄ are set.

V ₃ <V ₄ ... By setting the respective conveying speeds V ₃ and V ₄ to have such a relationship, the slack of the recording sheet P is not formed as much as possible in the vertical path portion 41. Like that.

Next, a description will be given of a leading end detecting operation of the image forming apparatus provided with the leading end detecting sensor 24 configured as described above.

When image formation in the continuous recording mode is set and a start command is issued, the control device 35 feeds the recording sheet P from the sheet feeding cassette 1B. here,
During this paper feed, the following recording pickup operation of the sheet P ₂ while the recording sheet P ₁ of the first sheet is not completely escape the paper feed cassette 1B is performed, thereby two recording sheets P
_1, P ₂ are overlapped.

Next, the leading end of the _first recording sheet P ₁ fed in an overlapped state is
11, it passes along the outer guide 27 due to the influence of the nip direction of the upstream conveying roller 23 directed to the outside of the main body, as shown in FIG. In other words, the non-detection area of the body outside of the recording sheet P ₁ from the distal end of the leading edge detection sensor 24 passes.

Next, this recording sheet P ₁ is
7, and then press the sensor arm 24a,
When Accordingly amount sufficient sensor arm 24a to the leading edge detecting sensor 24 as shown in FIG. 11 (b) detects the leading edge of the recording sheet P ₁ is rotated, the photo-interrupter 24b is turned ON Accordingly, Accordingly, the control device 35 detects the leading end of the _first recording sheet P1, and performs the above-described registration operation in the transport path 40 based on the detected timing.

[0066] Incidentally, the sensor arm 24a, when pushed by the leading edge of the recording sheet P _1, then the recording is not as fully retractable lead to negative effects on the conveyance of the sheet P, also returns to the original state by itself You can also.

On the other hand, after detecting the leading end, the control device 35 drives the downstream transport roller 25 together with the upstream transport roller 23. The two rollers 23, 25
Is the two rollers 23, 25 when carrying the recording sheet P ₁ of the first sheet, the recording sheet P ₂ of the second sheet which is conveyed by overlapping reaches the vicinity leading edge sensor By this time, the first recording sheet P1 is conveyed at such a speed difference that the slack of the _first recording sheet P1 is eliminated. Since this is based on the setting of the above equation, detailed description will be omitted.

When the slack of the _first recording sheet P ₁ is eliminated, that is, the first recording sheet P 1
_{When 1} is conveyed along the inner guide 26 of the vertical path section 41, the sensor arm 24a rotates downward as shown in FIG.

Next, when the first recording sheet P ₁ is further conveyed, the second recording sheet P ₂ eventually enters the vertical path section 41. Then, the second sheet of the recording sheet P ₂ is conveyed along the outer guide 27, finally pushes the sensor arm 24a at the tip, thereby the sensor arm 24a is round as shown in (b) of FIG. 12 When it moves, the photo-interrupter 24b is turned ON accordingly, whereby the control device 35 detects the leading end of the _second recording sheet P2. The leading edge of the third and subsequent recording sheets P is also detected by repeating this operation.

As described above, after the preceding recording sheet P ₁ that has entered the vertical path section 41 is conveyed along the outer guide 27, it is moved along the inner guide 26 and overlaps with the preceding recording sheet P _1. the transported follows the recording sheet P ₂ has the distal end, the preceding recording sheet P ₁ once in a vertical path portion
By separating from the rear end of, it is possible to reliably detect the leading end of the next recording sheet P _2.

[0071]

As described above, according to the present invention, the separation interval is set to zero, or the leading end of the next sheet which has entered the rear end of the preceding sheet with the leading end overlapped by a predetermined amount is separated by the separating mechanism. Is temporarily separated from the trailing edge of the preceding sheet in the transport path, and the leading edge of the separated next sheet is detected by the leading edge detecting means, so that the sheet is transported in a state where the sheet interval is 0 or slightly overlapped. In this case, the skew correction and the margin of the leading end can be ensured, so that an appropriate image can be formed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is an enlarged schematic view of a conveyance path for conveying a sheet material to an image forming unit in the image forming apparatus.

FIG. 3 is a control block diagram of the image forming apparatus.

FIG. 4 is a diagram illustrating a non-detection area of a leading end detection sensor of the image forming apparatus.

FIG. 5 is a view for explaining a state of tip detection by the tip detection sensor.

FIG. 6 is a diagram illustrating a leading edge detection operation of the image forming apparatus.

FIG. 7 is a diagram illustrating a leading edge detection operation of the image forming apparatus.

FIG. 8 is a diagram illustrating another configuration of the image forming apparatus.

FIG. 9 is a diagram illustrating a configuration of an image forming apparatus according to a second embodiment of the present invention.

FIG. 10 is an enlarged schematic diagram of a vertical path section of the image forming apparatus.

FIG. 11 is a diagram illustrating a leading edge detection operation of the image forming apparatus.

FIG. 12 is a diagram illustrating a leading edge detection operation of the image forming apparatus.

[Explanation of symbols]

 1, 1a, 1B Paper cassette 2 Vertical path roller 3 Tip detection sensor 3a Sensor arm 3b Photo interrupter 4 Registration member 5 Roller after registration 17 Lower guide 18 Upper guide 19 Roller after refeeding 23 Upstream transport roller 24 Tip detection Sensor 24a Sensor arm 24b Photo interrupter 25 Downstream transport roller 26 Inner guide 27 Outer guide 35 Controller 40 Transport path 41 Vertical path unit 50 Image forming unit 100 Image forming apparatus P Recording sheet S Loop space

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G03G 15/00 510 G03G 15/00 510 F-term (Reference) 2H072 AA03 AA13 AA24 AB09 CB06 3F048 AA02 AB01 BA21 CA04 CC03 EB22 3F049 AA02 DA12 DB02 EA13 EA24 EA28 LA01 LB03 3F101 FB02 FC11 FE17 LA01 LB03 3F102 AA01 AB01 BA02 BB02 CA03 CB01 DA06 EA03 FA03 FA06 FA08

Claims (6)

[Claims] An image forming section, a sheet storing section for storing sheets, and a conveying path for conveying the sheets stored in the sheet storing section toward the image forming section, wherein the sheet is provided in the conveying path. An image forming apparatus in which the sheet interval is set to 0, or the leading end of the next sheet is overlapped with the trailing end of the preceding sheet by a predetermined amount to enter, and the sheet interval is 0, or A separation mechanism for temporarily separating the leading end of the next sheet that has entered the conveyance path with a predetermined amount of overlap from the rear end of the preceding sheet in the conveyance path, and the next sheet separated by the separation mechanism. An image forming apparatus comprising: a leading edge detecting unit that detects a leading edge of a sheet. 2. The image forming apparatus according to claim 1, wherein the separating mechanism is configured to form the transport path and to oppose two guide members each having a bulging portion formed on one side thereof, and a first mechanism configured to cause the sheet stored in the sheet storage section to enter the transport path. Transport means, and a second transport means for transporting the sheet that has entered the transport path toward the image forming unit, after transporting the preceding sheet that has entered the transport path along the bulging portion, At the predetermined timing,
2. The apparatus according to claim 1, wherein a leading end of said next sheet is separated from a trailing end of said preceding sheet by being conveyed along the other of said two guide members.
The image forming apparatus as described in the above. 3. The sheet conveying speed of the second conveying means so that the preceding sheet conveyed along the bulging portion is conveyed along the other of the two opposing guide members. 3. The image forming apparatus according to claim 2, wherein the conveying speed is higher than the conveying speed. 4. The apparatus according to claim 1, wherein the leading end detecting means does not detect a preceding sheet conveyed along the other of the two guide members.
The image forming apparatus as described in the above. 5. A skew of the preceding sheet is corrected by contacting a preceding sheet that has entered along the bulging portion on the downstream side of the conveyance path and bending the preceding sheet along the bulging portion. The image forming apparatus according to claim 1, wherein the skew feeding correction member is provided so as to be able to move forward and backward. 6. The other of the two guide members forming the transport path is formed in a substantially linear shape, and the sheet transport direction of the first transport unit is set in a direction along one of the two guide members having the bulging portion. 3. The image forming apparatus according to claim 2, wherein: