JP3673613B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus that performs double-sided image formation in a non-stacking type.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image forming apparatus that performs double-sided image formation in a non-stacking type, the sheet is generally stopped at a predetermined position in the apparatus main body in order to refeed the sheet.
[0003]
[Problems to be solved by the invention]
However, in the above-described conventional example, the position where the sheet is stopped for refeeding is limited to only one position in the main body of the image forming apparatus. Therefore, when the sheet size is different, the position where the sheet is stopped is set. In contrast, since a plurality of control programs corresponding to the sheet size are required, the amount of program software constituting the control becomes enormous and complicated, increasing the occurrence of jams and reducing the production efficiency of double-sided image formation. There was a problem.
[0004]
SUMMARY An advantage of some aspects of the invention is that a plurality of sheet stop positions are provided in the image forming apparatus main body for refeeding, and the stop positions are the same regardless of the sheet size. By unifying the flow of sheets, the amount of software constituting the control is reduced, the occurrence of jams is reduced, and an image forming apparatus that improves the production efficiency of double-sided image formation is provided. Is.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a typical configuration according to the present invention includes a cassette for storing sheets, a sheet conveying means for conveying a sheet fed from the cassette, and an image on the sheet conveyed by the sheet conveying means. An image forming unit that forms an image according to information; a reversing path and a duplex conveying path for conveying a sheet to the image forming unit again to form an image on both sides of the sheet; and the reversing path and the duplex conveying A plurality of sheet stop control means for stopping the sheets, which are arranged on the path and on which the image is formed by the image forming means, at a plurality of different positions, and a plurality of sheets for detecting the movement state of the sheets at the plurality of sheet stop control means of the sheet detecting means, among the plurality of sheet stop control means, the sheet stop control hand sheet is stopped at a predetermined sheet stop control means When the sheet stop control means on the downstream side is vacant, the sheet stop control means is moved toward the downstream sheet stop control means, and stopped on the sheet stop control means upstream of the predetermined sheet stop control means. The standby release is performed to move the waiting sheet to the predetermined sheet stop control means, and if the number of sheets in the reversing path and the double-sided conveyance path is equal to or greater than a predetermined number, the plurality of sheet stops Among the control means, the sheet is sent from the sheet stop control means on the most downstream side in the sheet conveyance direction to the sheet conveyance means, and if the number of sheets in the reverse path and the double-sided conveyance path is equal to or less than a predetermined number, the sheet from the cassette And a controller that controls the sheet to be conveyed by the sheet conveying means .
[0006]
Since the present invention is configured as described above, the sheet is stopped at a plurality of positions by a plurality of sheet stop control means, and the sheet conveyance speed by the sheet stop control means is changed, so that both sides can be controlled by relatively simple control. Through-pass control can be performed.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment when applied to an electrophotographic copying machine as an example of an image forming apparatus according to the present invention will be specifically described with reference to the drawings. FIG. 1 is a cross-sectional explanatory view showing a configuration of an image forming apparatus according to the present invention, FIG. 2 is an external view of an operation panel of the image forming apparatus according to the present invention, and FIG. 3 is a configuration of a control system of the image forming apparatus according to the present invention. 4 is a block diagram showing the configuration of the image processing unit inside the scanner shown in FIG. 3, FIG. 5 is a flowchart showing double-sided feeding control, and FIG. 6 is a flowchart showing double-sided path control.
[0008]
In FIG. 1, reference numeral 1 denotes an image forming apparatus main body, and a lower deck cassette 2 for storing a sheet P made of paper, synthetic resin, or the like at the lower portion of the image forming apparatus main body 1, a third stage cassette 3, a fourth stage. An eye cassette 4 and a left deck cassette 5 are provided.
[0009]
The sheets P stored in the right deck cassette 2, the third stage cassette 3, the fourth stage cassette 4 and the left deck cassette 5 are selectively fed out by the pickup rollers 6, 7, 8, and 9, and are separated by a pair of separation feeding rollers 10. , 11, 12 and 13 are separated and fed one by one, and then are conveyed to a pair of conveying rollers 14, 15, 16, 17, 18, 19, 20, and 21 to reach a pair of registration rollers 22. In the present embodiment, the pickup rollers 6 to 9, the separating and feeding roller pairs 10 to 13, and the conveying roller pairs 14 to 21 constitute a sheet conveying unit that conveys the sheet P to the photosensitive drum 23 serving as an image forming unit.
[0010]
An electrophotographic photosensitive drum 23 serving as an image forming unit is disposed on the downstream side of the registration roller pair 22 in the sheet conveying direction (hereinafter simply referred to as “downstream side”), and faces the photosensitive drum 23. A transfer charger 24 is arranged.
[0011]
The sheet P that has reached the registration roller pair 22 has its tip abutted against the temporarily stopped nip portion of the registration roller pair 22 to form a loop to correct skewing, and then synchronizes with the rotation of the photosensitive drum 23. Then, the toner image formed on the surface of the photosensitive drum 23 is conveyed between the photosensitive drum 23 and the transfer charger 24 at a timing so that the image destination of the toner image and the image of the sheet P coincide with each other. The toner image formed on the photosensitive drum 23 is transferred onto the sheet P by the action of the transfer charger 24.
[0012]
The sheet P on which the toner image has been transferred is separated from the photosensitive drum 23 by the separation charger 25 and guided to the fixing device 27 by the conveying belt 26, where the toner image is permanently fixed by being heated and pressurized. Is done.
[0013]
When the sheet P on which the toner image is formed is discharged face-up so that the image surface faces upward, the sheet P discharged from the fixing device 27 is conveyed by the inner discharge roller pair 28 and discharged by the discharge switching flapper 29. It is guided to the roller pair 30 and conveyed by the outer discharge roller pair 30 and discharged face up on a discharge tray (not shown) provided outside the machine.
[0014]
When the sheet P on which the toner image is formed is discharged in a face-down manner in which the image surface is discharged downward, the sheet P discharged from the fixing device 27 is conveyed by the inner discharge roller pair 28 and is discharged by the discharge switching flapper 29. Once the sheet P is guided to the reversing path 31 and the sheet P is drawn by the reversing roller pair 32 and the trailing edge of the sheet P is detected by the sheet sensor 33, the sheet P is advanced by a predetermined distance. Is reversed and conveyed to the conveying roller pair 34 and the outer discharge roller pair 30, and discharged face down on a discharge tray (not shown) provided outside the apparatus.
[0015]
When images are formed on both sides of the sheet P, the sheet P that has come out of the fixing device 27 is transported by the inner discharge roller pair 28 and guided to the reverse path 31 by the discharge switching flapper 29, and by the reverse roller pair 32. After the sheet P is drawn and the sheet sensor 33 detects the trailing edge of the sheet P and advances a predetermined distance, the reversing roller pair 32 is reversed to guide the sheet P to the double-sided conveyance path 35 to be reversed. The sheet P is conveyed by the pairs 36, 37, 38, and further conveyed by the conveying roller pairs 20, 21, 18 to reach the registration roller pair 22, and on the second surface of the sheet P in the same manner as the first surface described above. Form an image.
[0016]
In FIG. 1, reference numerals 33 and 39 to 57 denote sheet sensors serving as a plurality of sheet detecting means arranged at various locations on the conveyance path of the image forming apparatus main body 1, and include an inner discharge roller pair 28, a reverse roller pair 32, and a conveyance roller pair. 36, 37, and 38 constitute a plurality of sheet stop control means disposed at various locations in the reversing path 31 and the duplex conveyance path 35. Here, the sheet stop control means on the most downstream side in the sheet conveying direction is constituted by a pair of conveying rollers 20, 38, and after the sheet sensor 54 detects the leading edge of the sheet P, the leading edge of the sheet P is, for example, a pair of conveying rollers. It is controlled to stop at a position of about 45 mm before 20.
[0017]
A document table glass 110 is provided on the upper surface of the image forming apparatus main body 1, and an automatic document feeder (not shown) is placed on the document table glass 110. Then, the image information of the document fed by the automatic document feeder is read by an image reading unit (not shown) disposed under the document table glass 110, and the toner image corresponding to the document image information is read by the photosensitive drum 23. Can be formed.
[0018]
FIG. 2 is an external view of the operation panel 61 provided in the image forming apparatus main body 1. In FIG. 2, 62 is a power switch for controlling energization to each unit in the image forming apparatus main body 1, and 63 is a reset key that operates as a key for returning to the standard mode during standby.
[0019]
64 is a copy start key, and 65 is a clear key used to clear a numerical value. 66 is an ID key. Unless a specific password is entered after the ID key is operated, the copying operation cannot be set and executed, so that only a specific operator can use the copying machine. Is possible.
[0020]
Reference numeral 67 denotes a stop key, which is used when the copying is interrupted or stopped. Reference numeral 68 denotes a guide key, which is used to know each function. Reference numerals 69, 70, 71, and 72 denote up, down, left, and right cursor keys, which are keys for moving the pointer up, down, left, and right on each function setting screen.
[0021]
Reference numeral 73 denotes an OK key which is operated when setting is approved on each function setting screen. Reference numeral 74 denotes a standard reduction key, which is used to reduce a standard-size original image to another standard size. Reference numeral 75 denotes an equal-size copy key, which is a key used when selecting an equal-size copy. 76 is a standard enlargement key, which is used to enlarge a standard-size original image to another standard size.
[0022]
A cassette selection key 77 is a key for selecting a cassette stage for supplying the sheet P. Reference numeral 78 denotes a copy density adjustment key, which is operated to reduce the density. Reference numeral 79 denotes an AE key which is used when the copy density is automatically adjusted with respect to the original density. Reference numeral 80 denotes a copy density adjustment key, which is used to increase the density.
[0023]
81 is a sorter key for designating the operation of the sorter, and 82 is a preheating key used for ON / OFF of the preheating mode. 83 is an interrupt key. Reference numeral 84 denotes a numeric keypad that is used to input numerical values such as the number of copies. Reference numeral 85 denotes a marker processing key, which is operated when setting trimming, masking, and partial processing (contour processing, halftone processing, shadowing processing, negative / positive processing).
[0024]
Reference numeral 86 denotes a patterning process key, which is used when a color is expressed in a pattern or a color is expressed by a density difference. A color erasure key 87 is used when a specific color on the original image is to be erased. Reference numeral 88 denotes an image quality key, which is used to set the output image quality.
[0025]
89 is a negative / positive key which is used when negative / positive processing is performed. Reference numeral 90 denotes an image create key, which is used when performing contour processing, shadowing processing, halftone processing, italics, mirror processing, and repeat processing. Reference numeral 91 denotes a trimming key, which is used to designate an area and perform trimming.
[0026]
A masking key 92 is used to specify an area and perform masking. Reference numeral 93 denotes a partial processing key, which is a key for designating partial processing (contour processing, halftone processing, shadowing processing, negative / positive processing) after designating an area.
[0027]
Reference numeral 94 denotes a frame erase key, which is used when performing frame erase according to the mode. To erase the frame, erase the sheet frame (create a frame for the sheet size), erase the original frame (create a frame according to the original size, and specify the original size), and erase the book frame (for the book spread size) In addition, there are three types: a frame and a blank in the center.
[0028]
Reference numeral 95 denotes a binding margin key, which is used when it is desired to create a binding margin at one end of the sheet P. 96 is a movement key, which is used when it is desired to move. The movement includes parallel movement (up / down / left / right), center movement, corner movement, and designated movement (point designation).
[0029]
Reference numeral 97 denotes a zoom key, which can set the copying magnification in the range of 25% to 400% in increments of 1% and can independently set the copying magnification in the main scanning and sub-scanning directions. Reference numeral 98 denotes an auto scaling key that automatically enlarges / reduces according to the size of the sheet P, and can auto-magnify the copying magnification in the main scanning and sub-scanning directions independently.
[0030]
99 is an enlargement continuous shooting key, which is used when one original is enlarged to a plurality of sheets for copying. Reference numeral 100 denotes a reduction layout key which is used when a plurality of documents are reduced and integrated on one output sheet.
[0031]
101 is a continuous shooting key, which is used to perform continuous copying (page continuous shooting, double-sided continuous shooting) that automatically divides the copy area on the platen glass 110 side into two parts and makes two copies automatically. It is. A double-sided key 102 is used when performing double-sided copying (double-sided copy of sheet P on one side of an original, double-sided copy of page P, double-sided copy of sheet P on both sides of an original).
[0032]
Reference numeral 103 denotes an enlarged layout key, which is used when copying after copying back a reduced layout (multiplexing, page continuous shooting multiplexing). Reference numeral 104 denotes a memory key which is used when a copy mode using an image memory is executed (memory composition, area composition, watermark composition).
[0033]
Reference numeral 105 denotes a projector key which is operated when copying using a film projector. Reference numeral 106 denotes a printer key, which is operated when outputting image data transferred from an external device. Reference numeral 107 denotes a reservation setting key, which is used when performing job reservation, correction, and deletion. Reference numeral 108 denotes a mode memory key, which is used to register a set copy mode in the memory and to call the registered copy mode.
[0034]
Reference numeral 109 denotes a display screen that displays the state of the image forming apparatus main body 1, the number of copies, the copy magnification, and the copy sheet size, and the setting contents during the copy mode setting. Also, when a situation where the copying operation cannot be continued such as a sheet jam occurs in the copying machine, a diagram, a moving image, a sentence, etc. for explaining the coping method are displayed.
[0035]
FIG. 3 is a functional block diagram of a control system of a digital copying machine having a local area network communication function. The operation panel 61, the scanner unit 111, and the control unit 112 include a CPU (central information processing unit) 113, an I / O (input / output unit) 114, a RAM (random access memory) 115, and a ROM (read only memory) 116. Based on the control program stored in the ROM 116, the operation of the components constituting each system is controlled.
[0036]
The RAM 115 is backed up by a battery so that the stored contents are not lost even when the power of the copying machine is cut off. The operation panel 61 is for controlling a user interface unit of the copying machine, and displays a message on a display screen 109 formed of an LCD (Liquid Crystal Display) and recognizes a user's key operation.
[0037]
A CPU (central information processing unit) 117 of the operation panel 61 performs data communication with the CPU 113 of the control unit 112 via a serial transmission line, and executes a copying operation according to a user operation and a message according to the copying operation. Can be displayed. For example, when a sheet jam occurs in the sheet conveying unit 119 of the printer unit 118, that is, when the sheet P remains in the sheet conveying unit 119 at the scheduled end time of copying, the CPU 113 detects the sheet by the sensor input from the I / O 114. The presence of P is detected, and the sheet jam message number is notified to the CPU 117.
[0038]
A control program for the CPU 117 is stored in the ROM 120. A character code string corresponding to the sheet jam message number is read, a bitmap-type character pattern corresponding to each character code is searched from the ROM 120, and the character pattern is developed in the RAM 121. The CPU 117 transfers the contents of the RAM 121 to the display screen 109, and the display of the character string is completed.
[0039]
FIG. 4 is a block diagram showing the configuration of the image processing unit 122 included in the scanner unit 111. The document image is scanned by the document scanning system 123 and input to a CCD (Charge Coupled Device) 124 disposed in the image sensor unit. The electrical signal (analog signal) corresponding to the density of the pixels sequentially sent from the CCD 124 is first converted into a digital signal having a level corresponding to the density by an A / D (analog / digital) converter 125.
[0040]
Thereafter, the level of the digital signal is adjusted by a black offset correction unit 126 for correcting offset variations in the black density of the CCD analog amplification unit, and then a shading correction unit 127 for correcting variations in the light amount distribution of the original illumination lamp. to correct. The signal is temporarily stored in the line memory 128.
[0041]
Document position recognition unit 129 recognizes the position of the document on the document table using the signal after shading correction. By changing the timing at which signals are written to the line memory 128 or read from the line memory 128, image scaling and movement processing is performed.
[0042]
When a signal is read from the line memory 128, a mirror image, folding, and repeat processing are performed by changing the reading method. The signal read from the line memory 128 is sent to the sharpness / filter / contour processing unit 130.
[0043]
In the sharpness / filter / contour processing unit 130, each processing is performed by calculating the density level for each pixel and sent to the density processing unit 131. The density processing unit 131 converts the level of the transmitted digital signal in accordance with the copy density setting information of the copying machine and outputs it.
[0044]
The trim / mask and negative / positive processing unit 132 of the negative / positive processing unit 132 inverts and outputs the level of the digital signal. In trim / mask processing, trim or mask processing is performed by changing a signal in a designated area or a signal outside the area to a designated density level.
[0045]
The add-on processing unit 133 reads out the information of the designated character from the memory in which character information is stored in advance and outputs it to the designated place instead of the image signal. The final 8-bit digital signal is sent to the printer unit 118, and the bright and dark portions are reproduced on the photosensitive drum 23 by turning on / off the laser.
[0046]
On the other hand, the scanner unit 111 has a RAM 134 serving as an image memory for storing document image information for a plurality of pages for storing document images scanned by the CCD 124 and image data transferred from the host computer. Used.
[0047]
For example, when the copying machine is operating in the remote control mode, image data sent from the external device via the LAN interface unit 135 is transferred to the RAM 134 by the CPU 113 and CPU 136 of the control unit 112.
[0048]
The CPU 113 and the CPU 136 communicate with each other via dual port RAMs built in the CPUs 113 and 136, respectively. The selector in the image processing unit 122 is switched by the CPU 136 in accordance with a command from the CPU 113, and the bitmap data in the RAM 134 is directly transferred to the printer unit 118.
[0049]
When an image processing operation is included in the command transferred from the CPU 113, the image data is transferred to the line memory 128, and designated image processing is executed. The image data read by the CCD 124 is sequentially processed by the image processing unit 122 and then transferred and stored in the RAM 134. The image data is sent to an external device via the CPU 113 and the LAN interface unit 135 of the control unit 112. Is possible.
[0050]
In this case, the selector 137 is switched to the channel 2, and the analog signal from the CCD 124 is transferred to the CPU 136 via the A / D converter 125, the black offset corrector 126, the shading corrector 127, and the selector 137.
[0051]
The CPU 136 sequentially stores data sent from the selector 137 in an appropriate area in the RAM 134 based on the scanning position information in the document scanning system 123 which is an optical scanning means. When the scanning is completed, the CPU 136 notifies the CPU 113 of the scanning end.
[0052]
The CPU 113 transmits an image data collection request command in the RAM 134 to the CPU 136 and then sends the image data sent from the CPU 136 to an external device via the LAN interface unit 135.
[0053]
In this manner, the present copying machine functions as a digital printer, a digital document scanner, and a stand-alone digital copying machine as peripheral devices of the external device. Switching control to each function is performed based on a control command transferred from an external device or an operation mode selection operation input from the operation unit.
[0054]
The LAN interface unit 135 includes a serial interface 138, a LAN controller 139, a bus controller 140, and a LAN connector 141. The LAN controller 139 performs overall control of each component in the LAN interface unit 135 and includes a CPU, a program ROM, a working RAM, and a FIFO.
[0055]
The local bus of the control unit 112 responsible for the medium access control (MAC) of IEEE 802.3 (general-purpose interface) is coupled via a bus controller 140. That is, the control CPU 113 of the control unit 112 accesses the LAN interface unit 135 through a specific I / O 114 space. A bus interface is used for data transfer at this time.
[0056]
The FIFO is for temporarily storing data at the time of transmission / reception. The capacity of the FIFO is increased to support communication with a higher transfer rate. The serial interface 138 performs transmission / reception of serial data, collision detection represented by CSMA / CD, and the like.
[0057]
Here, the data processed in the LAN controller 139 is converted into Ethernet data by Manchester encoding, and the data on the Ethernet is converted into a data format in the LAN controller 139 by Manchester decoding. The converted data is sent to the network via the LAN connector 141.
[0058]
The LAN interface unit 135 employed in the present embodiment realizes Ethernet LAN connection, and the I / O method is used for data communication between the CPU 113 and the LAN interface unit 135 for controlling the copying operation. An interface technology such as a connection method, for example, a talk ring method or a memory sharing method may be employed.
[0059]
FIG. 5 is a diagram showing a control flow of double-sided feeding of a control program executed by the CPU 113 of the control unit 112. First, in step S1, it is determined whether or not the numerical value is finished. If it is finished, the process is finished. If not completed, the process proceeds to step S2.
[0060]
In step S2, “1” is subtracted from the numeric value, and the process proceeds to step S3. In step S3, the number of images is checked. If it has been completed, the process proceeds to step S8. If not completed, the process proceeds to step S4. In step S4, "1" is subtracted from the number of images, and the process proceeds to step S5. In step S5, it is determined how many sheets P are in the reversing path 31 and the double-sided conveyance path 35. If the number of sheets P in the reversing path 31 and the double-sided conveying path 35 is equal to or greater than a predetermined number, the process proceeds to step S9. If it is equal to or less than the number, the process proceeds to step S6.
[0061]
In step S6, the sheet P is fed from the cassettes 2 to 5, and the process proceeds to step S7. In step S7, since the fed sheet P is sent into the reversing path 31 and the duplex conveying path 35, the number of sheets P in the reversing path 31 and the duplex conveying path 35 is incremented by "1", and the process proceeds to step S3.
[0062]
In step S8, if the sheet P remains in the reversing path 31 and the duplex conveyance path 35, the process proceeds to step S9. If not, the process returns to step S1. In step S9, the sheet P that has been waiting at a predetermined position in the reverse path 31 and the duplex conveyance path 35 is fed, and the process proceeds to step S10. In step S10, "1" is subtracted from the number of sheets P in the reversing pass 31 and the duplex conveyance pass 35, and the process proceeds to step S3.
[0063]
FIG. 6 is a diagram showing a flow of double-sided path control of a control program executed by the CPU 113 of the control unit 112. In this embodiment, this control is performed at two locations. In the first control area, the position of the sheet P is detected when the leading edge of the sheet P turns on the sheet sensor 33 shown in FIG. The reverse roller pair 32 is rotated at a normal speed set in advance to the drawing side at a point of about 30 mm, and then the sheet sensor 49 detects that the trailing edge of the sheet P has passed through the inner discharge roller pair 28 and reverses. The drawing speed by the roller pair 32 is set to double the normal speed.
[0064]
The reversing roller pair 32 is stopped when the trailing edge of the sheet P reaches the position 30 mm before the reversing roller pair 32. At this time, the process proceeds to step S21, and if the next path is free, the process proceeds to step S22. In step S22, the reversing roller pair 32 and the conveying roller pairs 36, 37, 38 are controlled to be conveyed to the conveying path side at a speed twice the normal speed, and after the sheet P passes the sheet sensor 54, the leading edge of the sheet P is controlled. Stops when it reaches 45 mm in front of the pair of conveying rollers 20, and proceeds to step S23.
[0065]
In step S23, the resource is released so that the path resource that has been used so far can be used by the rear sheet P, the standby path area is updated, and the process proceeds to step S24. In step S24, if the pass position that has just stopped is the final standby position, the process proceeds to step S27; otherwise, the process returns to step S21.
[0066]
In step S27, a feed request OK signal from both sides is output to the feed control flow of FIG. In steps S25 and S26, since the sheet P has waited before, the pair of reversing rollers 32 is stopped, and the next pass is released and waits until the standby is released.
[0067]
When the standby is canceled, the process returns to step S21. Further, the control release in the second control area is notified to the rear sheet P when the rear end of the sheet P passes through the sheet sensor 54. As described above, by stopping the sheet P at a plurality of positions and changing the conveyance speed between them, it is possible to control the double-sided through path with a simple flowchart and uniform control regardless of the sheet size. .
[0068]
【The invention's effect】
Since the present invention has the configuration and operation as described above, the non-stack type double-sided image forming processing is performed with a relatively simple control by performing the standby of the sheet at a plurality of positions, and is uniform regardless of the sheet size. Control can be performed, and the occurrence rate of sheet jam or the like can be reduced, and double-sided processing with high production efficiency can be provided.
[Brief description of the drawings]
FIG. 1 is an explanatory cross-sectional view showing a configuration of an image forming apparatus according to the present invention.
FIG. 2 is an external view of an operation panel of the image forming apparatus according to the present invention.
FIG. 3 is a block diagram illustrating a configuration of a control system of the image forming apparatus according to the present invention.
4 is a block diagram illustrating a configuration of an image processing unit in the scanner illustrated in FIG. 3;
FIG. 5 is a flowchart illustrating duplex feeding control.
FIG. 6 is a flowchart showing double-sided path control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus main body, 2 ... Right deck cassette, 3 ... 3rd stage cassette, 4 ... 4th stage cassette, 5 ... Left deck cassette, 6-9 ... Pickup roller, 10-13 ... Separation feeding roller pair, 14 to 21: transport roller pair, 22: registration roller pair, 23: photosensitive drum, 24: transfer charger, 25: separation charger, 26: transport belt, 27: fixing device, 28: inner discharge roller pair, 29 ... Discharge switching flapper, 30 ... Outside discharge roller pair, 31 ... Reverse path, 32 ... Reverse roller pair, 33 ... Sheet sensor, 34 ... Conveying roller pair, 35 ... Double-sided conveyance path, 36-38 ... Conveying roller pair, 39- 57 ... Seat sensor 61 ... Operation panel 62 ... Power switch 63 ... Reset key 64 ... Copy start key 65 ... Clear key 66 ... ID key 67 ... Stop key 68 ... Guide key 69-72 ... Cursor key, 73 ... OK key, 74 ... Standard reduction key, 75 ... Same size copy key, 76 Standard enlargement key, 77 ... Cassette selection key, 78 ... Copy density adjustment key, 79 ... AE key, 80 ... Copy density adjustment key, 81 ... Sorter key, 82 ... Preheat key, 83 ... Interrupt key, 84 ... Numeric keypad, 85 ... Marker Processing key, 86 ... Pattern processing key, 87 ... Color erase key, 88 ... Image quality key, 89 ... Negative positive key, 90 ... Image create key, 91 ... Trimming key, 92 ... Masking key, 93 ... Partial processing key, 94 ... Frame erase key, 95 ... Binding key, 96 ... Move key, 97 ... Zoom key, 98 ... Auto scaling key, 99 ... Enlarged continuous shooting key, 100 ... Reduction layout key, 101 ... Continuous shooting key, 102 ... Double-sided key, 103 ... Enlarged layout key, 104 ... Memory key, 105 ... Projector key, 106 ... Printer key, 107 ... Reservation setting key, 108 ... Mode memory key, 109 ... Display screen, 110 ... Original platen glass, 111 ... Scanner section, 112 ... control unit, 113 ... CPU, 114 ... I / O, 115 ... RAM, 116 ... ROM, 117 ... CPU, 118 ... Printer unit, 119 ... Sheet conveying unit, 120 ... ROM, 121 ... RAM, 122 ... Image processing unit, 123 ... Document Scanning system, 124 ... CCD, 125 ... A / D converter, 126 ... 126 ... Black offset correction unit, 127 ... Shading correction unit, 128 ... Line memory, 129 ... Document position recognition unit, 130 ... Sharpness / filter / contour processing 131, density processing unit, 132 trim / mask, negative / positive processing unit, 133 add-on processing unit, 134 RAM, 135 LAN interface unit, 136 CPU, 137 selector, 138 serial interface, 139 ... LAN controller, 140 ... Bus controller, 141 ... LAN connector, P ... Sheet

Claims (3)

A cassette for storing sheets;
Sheet conveying means for conveying a sheet fed from the cassette ;
Image forming means for forming an image on the sheet conveyed by the sheet conveying means according to image information;
A reversing path and a duplex conveying path for conveying the sheet to the image forming means again to form an image on both sides of the sheet;
A plurality of sheet stop control means arranged on the reversing path and the double-sided conveyance path and stopping the sheet on which the image is formed by the image forming means at a plurality of different positions;
A plurality of sheet detecting means for detecting the movement state of the sheets in the plurality of sheet stop control means;
Among the plurality of sheet stop control means, when the sheet stop control means on the downstream side of the sheet stop control means is vacant for the sheet stopped by the predetermined sheet stop control means, the downstream seat stop control means The standby release is performed in order to move the sheet that has been stopped by the sheet stop control means upstream of the predetermined sheet stop control means and moved to the predetermined sheet stop control means. Further, if the number of sheets in the reversing path and the double-sided conveyance path is equal to or greater than a predetermined number, the sheet is conveyed from the sheet stop control unit on the most downstream side in the sheet conveyance direction among the plurality of sheet stop control units. If the number of sheets in the reversing path and the double-sided conveying path is less than a predetermined number, the sheet is fed from the cassette and the sheet conveying hand A control unit for controlling to convey by,
An image forming apparatus comprising:   The sheet conveyance speed of the sheet stop control unit on the upstream side in the sheet conveyance direction is faster than the sheet conveyance speed of the sheet stop control unit on the most downstream side in the sheet conveyance direction. 2. The image formation according to claim 1, wherein the sheet conveyance speed of the sheet stop control unit on the most downstream side in the sheet conveyance direction is set equal to the sheet conveyance speed of the sheet conveyance unit. apparatus.   Among the plurality of sheet stop control means, after the sheet stop control operation by the predetermined sheet stop control means is completed, the sheet stop control means upstream of the sheet conveyance direction from the sheet stop control means performs the sheet stop control operation. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to start.

Images