JPH10333380A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of performing only the required both side image formation without performing the new image formation on a sheet remaining in an intermediate tray even in the case of newly starting the both side image formation, from a state that the sheet remains inside this intermediate container means, as the image forming device provided with the both side image forming function, and equipped with the intermediate containing means such as an intermediate tray for temporarily containing the sheet that the image is formed on one side thereof in order to form images on both side of the sheet (for instance, both side copying). SOLUTION: In order to perform the both side copying, plural copying sheets of paper that the image is formed on the front side is temporally contained, in the intermediate tray 19, then, until the size of paper sheet in the intermediate tray 19 to be detected by sensors SE8 and SE9 arranged on the bottom part of the tray 19 is changed, the paper sheets contained in the tray 19 are transported to a transferring position in order to form the image on the paper sheet rear side.

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 such as a copying machine and a printer, and more particularly to an image forming apparatus having a double-sided image forming (for example, double-sided copying) function.

[0002]

2. Description of the Related Art Some image forming apparatuses such as copying machines and printers have a function of forming an image on both sides of a sheet (usually paper). For example, when performing double-sided copying in a copying machine having a double-sided copying function,
On the front side (first side), image formation is performed on paper fed from the initial paper feed tray that stores blank paper, as in the case of performing single-sided copying. In the case of single-sided copy, the sheet is directly discharged to the outside of the apparatus. In the case of double-sided copy, the sheet on which an image is formed on the surface is
The sheet is temporarily stored in the intermediate tray, then fed out of the intermediate tray, and the image is formed on the back surface (second surface) of the sheet, and then discharged out of the apparatus. When performing double-sided copying of a plurality of copies, the single-sided copied sheets of the plurality of copies are temporarily stored in the intermediate tray, and the sheets are sequentially discharged from the intermediate tray, and an image is sequentially formed on the back surface of the sheet. You.

However, if the user inputs a key such as a copy stop key to stop copying for some reason during double-sided copying, or if there is no more paper in the initial paper feed tray, the paper to be replenished at that time is lost. When the user leaves the place because the user is not near or the copier is abandoned, the copier may be stopped with sheets remaining in the intermediate tray.

[0004] As described above, various proposals have been made regarding the handling of the sheet remaining on the intermediate tray when the two-sided copy is to be started again with the sheet remaining in the intermediate tray. For example, in Japanese Patent Application Laid-Open No. 5-249775, when a double-sided copy mode is newly set in a case where sheets are left in the intermediate tray, the sheets remaining in the intermediate tray are replaced with the back side (the 2
Forcibly discharging the sheet to the outside without forming an image.

[0005]

However, in the method taught in Japanese Patent Application Laid-Open No. Hei 5-249775, when a new double-sided copy is performed from the state where the sheets remain in the intermediate tray, all the sheets remaining in the intermediate tray are removed. After waiting for the paper to be ejected outside the machine, you must perform duplex copying.
It is not easy to use.

When a new double-sided copy is to be performed from a state in which the sheets remain in the intermediate tray, sheets discharged from the intermediate tray for forming an image on the second surface (rear surface) are first placed in the tray. If the sheet is discharged from the sheet that has been conveyed last, a new desired double-sided copy can be performed without discharging the remaining sheet in the intermediate tray even if the sheet remains in the intermediate tray. However, even in this case, when the two-sided copy is performed until the sheet in the intermediate tray runs out, the image formation on the back side of the sheet is performed by a new user on the sheet on which the image is formed on the front side in order to perform a new two-sided copy. The process is also performed on the sheets remaining in the intermediate tray at the time when double-sided copying is newly started. That is, the image forming is also performed on the back side of the sheet remaining on the intermediate tray at the time of starting a new two-sided copy (the front side of the sheet has a copied image in order to perform the two-sided copy by the previous user). Therefore, unnecessary image formation is also performed for a user who performs a new double-sided copy, and it takes extra time to complete the double-sided copy. further,
Later sorting is also required.

In the above description, a copying machine has been described as an example. However, similar problems also occur in an image forming apparatus such as a printer other than the copying machine. Therefore, the present invention has a double-sided image forming function and has an intermediate storage means such as an intermediate tray for temporarily storing a sheet having an image formed on one side in order to form an image on both sides of the sheet (for example, duplex copying). In the image forming apparatus, even when new double-sided image formation is started from a state in which a sheet remains in the intermediate storage unit, new double-sided image formation is not performed on the sheet remaining in the intermediate tray. Another object of the present invention is to provide an image forming apparatus capable of performing only necessary double-sided image formation.

[0008]

According to the present invention, there is provided an image forming apparatus for forming an image on a sheet based on document image information, and an image forming apparatus for forming an image on a conveyed sheet based on the document image information. Image forming means capable of forming a sheet, an intermediate storing means capable of temporarily storing a sheet having an image formed on one surface by the image forming means, and a sheet stored in the intermediate storing means. An image forming apparatus comprising: a conveying unit capable of conveying the sheet to a forming unit, wherein the sheet size detecting unit detects a sheet size in the intermediate storing unit, and the intermediate storing unit detects the sheet size in the intermediate storing unit. A control means for determining whether or not to convey the sheet from the intermediate storage means to the image forming means based on the size of the sheet; Has the door, said control means, until the size of the sheet said housed in the intermediate housing means to be detected of the sheet size detecting means is changed,
An image forming apparatus is provided, wherein the conveying unit conveys a sheet stored in the intermediate storing unit to the image forming unit.

Examples of the image forming apparatus include a digital copying machine, an analog copying machine, a printer, and a composite machine thereof. According to the image forming apparatus of the present invention, in the case where double-sided image formation is performed from a state where there is no sheet in the intermediate storage unit, the sheet on which image formation is performed on one surface (first surface) by the image forming unit is subjected to double-sided image formation. Are stored in the intermediate storage means. In addition, these sheets
Normally, sheets of the same size set by the user as the size of a sheet on which a double-sided image is to be formed. And
The sheets stored in the intermediate storage unit are sequentially conveyed again to the image forming unit by the conveying unit, and an image is formed on the other surface (second surface), whereby images are formed on both surfaces of the sheet. At this time, there is no sheet in the intermediate storage unit from the intermediate storage unit until the size of the sheet stored in the intermediate storage unit changes, that is, usually at the time when double-sided image formation is started. Therefore, since the sheets newly stored in the intermediate storage means are usually the same size, the control means causes the conveyance means to convey the sheets until there are no more sheets stored in the intermediate storage means. Therefore, after the two-sided image formation, the sheet usually does not remain in the intermediate storage unit. The sheets on which images are formed on both sides are discharged outside the apparatus, for example, on a discharge tray.

When a new double-sided image formation is started with the sheets remaining in the intermediate storage means, the same as in the normal case (two-sided image formation from a state where there is no sheet in the intermediate storage means), The sheets on which an image has been formed on one side are temporarily stored in the intermediate storage means for the number of sheets to be formed on both sides.
Also in this case, the sheets newly stored in the intermediate storage means are usually the same size set by the user as the size of the sheet to be subjected to double-sided image formation. Then, the control unit causes the conveying unit to sequentially re-convey the sheet to the image forming unit until the size of the sheet stored in the intermediate storing unit changes, and the back side of the conveyed sheet (the Image formation is sequentially performed on (2 sides), and images are formed on both sides of the sheet. If a sheet conveyed from the intermediate storage unit to the image forming unit is conveyed from the sheet stored last in the intermediate storage unit, desired double-sided image formation can be performed. Therefore, at the time when new double-sided image formation is started, the size of the sheet remaining in the intermediate storage means and
When the size of a sheet newly stored in the intermediate tray for forming a new double-sided image (the size is usually set by a user) is different, the sheet is conveyed from the intermediate storing unit to the image forming unit by the conveying unit. The sheet to be changed is the sheet until the size of the sheet changes, and therefore, only the sheet newly stored in the intermediate storage means, and the sheet remaining in the intermediate storage means at the time of forming a new two-sided image is the image forming means. The sheet is not conveyed, and the image is prevented from being formed on the back surface of the remaining sheet.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of an analog copying machine according to an embodiment of the present invention. This copying machine has a double-sided copying function for copying a document image on both sides of a sheet. This copying machine forms a toner image on a sheet by an electrophotographic method based on a scanning optical system S1 for scanning an image of a document placed on a document table glass GL and a document image read by the scanning optical system S1. Drum and a device disposed around the same, a fixing device 17 for fixing a toner image formed on the sheet, sheet trays 18a and 18b for storing the sheet, and the above-described double-sided copying For this purpose, an intermediate tray 19 is provided. At the top of the copier, an operation panel 4 is provided for a user to issue a copy start instruction or the like. In addition, a cover 3 that is openably and closably mounted is disposed above the platen glass GL. Note that, instead of the cover 3, an automatic document feeder (ADF) also serving as a cover may be assembled so as to be openable and closable.

The scanning optical system S1 also serves as an exposing device for exposing the photosensitive drum PC to an image, and illuminates the original placed on the original platen glass GL with an illumination lamp 10; Reflection mirrors M1, M2 leading to LN,
M3, a lens LN, and a reflection mirror M4 for guiding the image light passing through the lens LN to the photosensitive drum PC. The illumination lamp 10 and the reflection mirror M1 are connected to the carriage C
1 and the reflection mirrors M2 and M3 are supported by the carriage C2.

A charger 11 is provided around the photosensitive drum PC.
Developing device 12, transfer charger 13, separation charger 1
4, a cleaner 15 and an eraser 16 are sequentially arranged. The sheet trays 18a and 18b are arranged at the lower part of the copying machine, and in these sheet trays, in this example,
A plurality of sheets (blank sheets) on which no image is formed are stored on both sides. In this example, A4 size paper is stored in the upper sheet tray 18a in the horizontal direction.
A3 size paper is stored in the lower sheet tray 18b in a horizontal direction.

From these sheet trays, the photosensitive drum PC
Between the transfer position where the transfer charger 13 and the transfer charger 13 face each other,
02 and 21 are provided in order. Note that a roller group for conveying a sheet is provided in these conveyance paths. Similarly, a roller group for sheet conveyance is provided in a conveyance path described later. The paper stored in the upper sheet tray 18a can be sent out to the transport path 202 by the paper feed roller group 181a, and can be transported to the transfer position via the transport path 21. Similarly, the sheets stored in the lower sheet tray 18b can be sent out to the conveyance path 201 by the sheet feeding roller group 181b,
The sheet can be transported to the transfer position via the transport paths 202 and 21.

Sensors SE1 and SE2 are arranged near the sheet feed ports of the sheet trays 18a and 18b, respectively.
The sheet conveyed to can be detected. A sensor SE3 is disposed immediately before the position where the conveyance path 201 and the conveyance path 21 join, and can detect a sheet passing through the position. The detection signal of each of these sensors is
It is input to a computer CP described later (see FIG. 4).

A sheet conveying belt 22 is disposed between the fixing device 17 and a separation position where the photosensitive drum PC and the separation charger 14 are opposed to each other. Downstream of the fixing device 17 in the sheet conveyance direction,
Transport paths 23 and 24 are provided, and a transport direction switching claw 26 is disposed at a branch point between the two transport paths. The switching claw 26 is oriented upward in FIG. 1 (indicated by a solid line in FIG. 1) or downward (indicated by a dotted line in FIG. 1) by a solenoid SOL1.
The sheet can be distributed to any one of the transport paths (the transport path 23 or the transport path 24) by the swing of the claw 22. A discharge tray 27 is disposed at the end of the transport path 23, and an intermediate tray 19 is disposed at a point of the transport path 24. A sensor S is provided below the discharge tray 27.
E4 is disposed, and the presence or absence of a sheet on the discharge tray 27 can be detected. Further, a sensor SE5 is disposed near the position immediately before the intermediate tray 19 on the transport path 24, and can detect a sheet that passes through the transport path 24 and is loaded into the intermediate tray 19. These sensors SE
The detection signals 4 and 5 are input to the computer CP.

FIG. 2A is a plan view of the intermediate tray 19.
FIG. 2B is a sectional view of the intermediate tray 19. The intermediate tray 19 has a box shape with an open upper side, and sheets are carried into the tray 19 from the opening. Intermediate tray 1
9, a rail 192 is disposed below the bottom surface 191, and an alignment plate 193 that stands substantially perpendicularly to the bottom surface 191 is fitted to the rail 192 so that a part thereof projects from the hole 194. . The alignment plate 193 can be reciprocated along the rail 192 by driving means (not shown), and such movement (up and down movement in FIG. 2A).
Thereby, a plurality of sheets S of the same size that are carried into the tray 19 and stacked and stored can be aligned at the end in the direction perpendicular to the carrying direction (the end in the vertical direction in FIG. 2A). . In the copying machine, the intermediate tray 19 is arranged such that the bottom surface 191 is inclined with respect to the horizontal direction, as shown in FIG. 2 (ends in the left-right direction in FIG. 2A). Thus, sheets S of the same size stacked and stored in the tray 19 can be aligned with their four corners aligned. In this example, each time one sheet is carried into the tray 19, the alignment plate 193 is driven to align the ends. In this manner, the four corners of the sheet conveyed into the intermediate tray 19 are aligned when forming an image on the second surface (back surface) for double-sided copying by storing the sheet in the intermediate tray 19 as described later. When a sheet that is tilted in the intermediate tray 19 is conveyed to the transfer position when the sheet is conveyed to the transfer position, an image formed on the sheet is tilted on the sheet. This is to prevent such a problem because the sheet is likely to be jammed or jammed. Also,
A push-up plate 195 is provided on the bottom surface 191 of the intermediate tray 19 so as to be swingable about a shaft 1951. The push-up plate 195 can be swung by driving means including a motor (not shown). When a sheet is carried into the intermediate tray 19, the push-up plate 1
95 is arranged so as to be flush with the bottom surface 191. When the sheet stored in the intermediate tray 19 is carried out from the tray, the sheet is supplied to a sheet feeding roller group 28 (strictly, one roller in the roller group 28) disposed above the tray 19. Is raised, the push-up plate 195 is swung so as to raise the sheet.

An intermediate tray 1 is provided below the intermediate tray 19.
9 (A4 or A3 in this example)
The sensors SE8 and SE9 are arranged in order to detect. The sensor SE8 has A4 in the intermediate tray 19.
When either the paper of A3 or the paper of A3 is stored,
The sensor SE9 is arranged at a position where it is possible to detect the presence of paper in the intermediate tray 19, and the sensor SE9 cannot detect the presence of paper in the intermediate tray 19 unless A3 paper is stored in the intermediate tray 19. Is located in the position.
Accordingly, when the sensor SE9 detects that there is a sheet in the intermediate tray 19 (at this time, the sensor SE8 also detects that there is a sheet), the intermediate tray 19
A3 paper is stored in the inside, the sensor SE9 detects that there is no paper, and the sensor SE9 detects that there is no paper.
8 detects that there is a sheet, the intermediate tray 19
It can be seen that A4 paper is stored in the box. In addition,
The detection information of the sensor SE8 is also used to detect whether or not there is a sheet in the intermediate tray 19. The detection signals of these sensors SE8 and SE9 are input to the computer CP.

As described above, the intermediate tray 19 receives sheets from above, and the sheets once stacked and stored in the intermediate tray 19 are separated from the upper-layer sheets by the sheet feed roller group 28, the push-up plate 195, and the like. In order, transport path 2
1 can be sent out to the transport path 25 leading to 1. That is, the sheets stored in the tray 19 are sent out in order from the sheet most recently carried into the intermediate tray 19. A sensor SE6 is disposed near the conveyance path 25 immediately after the sheet feeding port of the intermediate tray 19, and can detect a sheet discharged from the intermediate tray 19 and passing through the conveyance path 25. Further, a sensor SE7 is disposed immediately before the converging position of the conveying path 25 and the conveying path 21, and can detect a sheet passing through the position. Sensor SE
6. The detection signal of SE7 is input to the computer CP.

FIG. 3 is a plan view of the operation panel 4. The operation panel 4 includes a start key 41 for instructing a copy start, a numeric keypad 42 for inputting a numerical value (number) such as the number of copies, a clear key 46 for clearing the input numerical value, and a copy stop. A stop key 47 for instructing, a copy mode setting key 43 for selecting and setting a copy mode (in this example, a one-sided copy mode or a two-sided copy mode), and a paper feed port (in other words, the sheet trays 18a, 18b) ) Is provided, and a display panel 45 for displaying various messages, the number of copies to be set, and the like is provided. Display panel 45
Inside, a DUP warning display lamp 451 is provided for lighting and indicating that the sheet remains in the intermediate tray 19.

Copy mode display LEDs 43a and 43b for lighting and displaying whether the set copy mode is the one-sided copy mode or the two-sided copy mode,
The selected paper feed port display LEDs 44a and 44b for lighting and displaying whether the set paper feed port is the upper sheet tray 18a or the lower sheet tray 18b, or the selected paper size is A4 landscape (A4Y) Paper size display LED 44 that lights up and displays whether it is A3 or A3.
c, 44d are also provided. The sheet on which the toner image is to be transferred at the transfer position is a selected tray (in this example, the upper sheet tray 18a and the lower sheet tray 1).
8b or the intermediate tray 19), and the paper feed port setting key 44 is used for the first side (front side) when performing one-sided copying and when performing two-sided copying.
Is set for the tray (in this example, the upper sheet tray 18a or the lower sheet tray 18b that stores blank paper) that stores the sheet to which the toner image is to be transferred when making a copy of the image. Things. Selected paper feed port display LEDs 44a, 44b and selected paper size display LEDs
Reference numerals 44c and 44d illuminate and display the paper feed port and paper size selected by the paper feed port setting key 44.

The scanning optical system S1, the photosensitive drum PC, peripheral devices of the photosensitive drum PC, the fixing device 17,
The operation panel 4, the sensors SE1 to SE9, the roller group for conveying the sheet, and the like are all connected to the computer CP as shown in FIG. The computer CP includes a read-only memory (not shown) and a random access memory (not shown) that store a control program and the like for each device.

Under the control of the computer CP, each device of the copying machine controls the number of copies (number of copies) set by key input on the operation panel 4, the copy mode (single-sided copy mode or double-sided copy mode), and the sensor SE1. One-sided copy or two-sided copy is performed by operating as follows based on input information of SE9. For single-sided copying, the document to be copied is placed at a predetermined position on the platen glass GL with the cover 3 opened by the user. When the start key 41 is pressed, image reading by the scanning optical system S1 is started.

When an image is read by the scanning optical system S1, the illumination lamp 10 mounted on the carriage C1 is turned on.
The carriage C1 is driven in the sub scanning direction X. At this time, the carriage C1 is driven at a predetermined speed, and the carriage C2 is also driven in the same direction at half the speed of the carriage C1. The reflected image light from the original is reflected by the reflection mirror M
The light is sequentially guided to the imaging lens LN via 1, M2, and M3. The light that has passed through the imaging lens LN is guided to the exposure position of the photosensitive drum PC by the reflection mirror M4.

At this time, the photosensitive drum PC is driven to rotate counterclockwise in FIG. 1 at a predetermined speed, and its surface is uniformly charged by the charging charger 11. An electrostatic latent image is formed on the charged photosensitive drum PC at the exposure position by the image forming light of the original image guided by the reflection mirror M4. This electrostatic latent image is developed by the developing device 12 to become a toner image, and the toner image is transferred onto a copy sheet by the transfer charger 13.

The sheet stored in the sheet tray (either the upper sheet tray 18a or the lower sheet tray 18b) selected by the sheet feeding port setting key 44 of the operation panel 4 passes through the transport path 21. It is transported to the transfer position. The sheet on which the toner image has been transferred is separated from the photosensitive drum PC by the separation charger 14 and is conveyed to the fixing device 17 by the sheet conveying belt 22. In the fixing device 17, the paper holding the toner image passes between the heating roller 171 heated to a predetermined fixing temperature and the pressure roller 172 pressed by the heating roller 171 while being pinched. Then, the toner image is fixed on the paper under pressure. The sheet on which the toner image has been fixed is guided to the transport path 23 by the switching claw 26 turned downward (dotted line position in FIG. 1), and is discharged onto the discharge tray 27. The one-sided copy is completed by repeating the above operation for the set number of copies (number of copies).

In the case of double-sided copying, the sheet stored in the sheet tray (upper sheet tray 18a or lower sheet tray 18b) selected by the paper feed port setting key 44 is processed in the same procedure as in the case of single-sided copying. The toner image is transferred and fixed to the first surface (front surface) of the sheet, and the paper on which the single-side copy has been made is not discharged to the discharge tray 27, but is transported by the switching claw 26 turned upward (solid line position) in FIG. Then, the sheet is once carried into the intermediate tray 19. The image formation on one side of the sheet is repeated by the set number of copies (number of copies), and the single-side copied sheets of the set number of copies (number of copies) are temporarily stacked and stored in the intermediate tray 19. In this example, each time one sheet of paper is carried into the intermediate tray 19, the four corners of the sheet are aligned by the alignment plate 193 or the like.

Then, image reading and image copying are performed in the same manner for the second document. At this time, the sheet supplied to the transfer position is the one-side copied sheet temporarily stored in the intermediate tray 19. The sheet is sent out to the transport path 21 via the transport path 25 by the paper feed roller group 28 and the like. When the image formation on the first side (front side) of the sheet has been completed for the set number of sheets, the selected sheet supply port is switched to the sheet supply port of the intermediate tray 19. This paper is fed to the transport path 25
When the toner image is sent to the transport path 21 by the image forming apparatus, the toner image is turned upside down from the image formed on the first surface at the transfer position. Transcribed. Then, the toner image is fixed by the fixing device 17 in the same manner as described above. In this case, the toner image is guided to the transport path 23 by the switching claw 26 turned downward, and is discharged onto the discharge tray 27. Such an operation is performed until the sheets temporarily stored in the intermediate tray 19 are exhausted, and the double-sided copying ends.

In the case of double-sided copying, normally, no paper remains in the intermediate tray 19 as described above.
While the duplex key is being executed, the stop key 47 of the operation panel 4 is pressed to interrupt the duplex copy, and the intermediate tray 1 is stopped.
In some cases, the copier may stop with paper remaining in the printer. Hereinafter, the operation of the copier relating to the handling of the paper when the paper remains in the intermediate tray 19 will be described by a computer CP.
This will be described with reference to flowcharts shown in FIGS. FIG. 5 is a flowchart showing the main routine.

When the power switch of the copier is pressed to turn on the power, the computer CP is initialized (step S1 in FIG. 5). When the initial setting is completed, the timer of the computer CP is set to a predetermined time,
The process is started (S2), and the subsequent processes (S4 to S9) are repeated at the set time intervals. First, it is determined whether copying is in progress (S3). When copying is not being performed (S3: NO), the copy mode key processing (S4) and the paper feed port switching processing (S5) are performed, and then the intermediate tray paper feeding routine (S6), the automatic discharge routine (S7), the copy conditions The processing (S8) and other processing (S9) are performed, and after the timer set in step S2 is completed (S1).
0) One routine ends, and the process returns to step S2.

When copying is in progress (S3: YE
S), the processes in steps S6 to S9 are performed, and after the timer is finished (S10), one routine is finished, and the process returns to step S2 again. Hereinafter, a copy mode key process (S4), a paper feed port switching process (S5), and an intermediate tray paper feed routine (S5), which are subroutines of the main routine shown in FIG.
6), automatic discharge routine (S7), copy condition processing (S
8) and other processing (S9) will be described in more detail. (A) Copy Mode Key Processing FIG. 6 is a flowchart showing the copy mode key processing. In the copy mode key processing, when the copy mode setting key 43 of the operation panel 4 is pressed, the copy mode (one-sided copy mode or two-sided copy mode) is switched.

That is, when the copy mode setting key 43 is pressed and an on-edge of the key 43 (a state change when the state changes from the off state to the on state, the same applies hereinafter) is detected (S41: YES), the current copy is performed. It is determined what the mode is (S42). When the one-sided copy mode is set and the one-sided copy mode display LED 43a is lit (S42: YES), the copy mode is changed to the two-sided copy mode, and the two-sided copy mode display LED 4
3b is turned on (S43), and the one-sided copy mode display LE is displayed.
D43a is turned off (S44).

When the two-sided copy mode is set and the one-sided copy mode display LED 43a is turned off (S42: NO), the copy mode is changed to the one-sided copy mode, and the one-sided copy mode display LED 43a is turned on (S45). ), Double-sided copy mode display LED 43b
Is turned off (S46). As described above, in the copy mode key processing, each time the copy mode setting key 43 is pressed, the copy mode is changed from the single-sided copy mode (or double-sided copy mode) set when the key is pressed to the double-sided copy mode (or (Simplex mode). (B) Paper Feed Port Switching Process Next, the paper feed port switching process (Step S5 in FIG. 5) will be described with reference to FIG. In the paper supply port switching process, when the paper supply port setting key 44 on the operation panel 4 is pressed, the paper supply port for the initial paper supply to the transfer position is set to the supply port of the upper sheet tray 18a. The paper port or the paper feed port of the lower sheet tray 18b is switched.

That is, the paper feed port setting key 44 is pressed,
When the on-edge of the key 44 is detected (S51: YE
S), it is determined what the current paper feed port is (S5).
2). When A4 landscape paper is set and the upper sheet tray selection display LED 44a is lit (S5
2: YES), the sheet feeding port is located at the lower sheet tray 18b (A3
Sheet is stored), the upper sheet tray selection display LED 44a is turned off,
The lower sheet tray selection display LED 44b is turned on (S53). In addition, the A4 paper selection display LED 44c is turned off, and the A3 paper selection display LED 44d is turned on (S54).

When A3 paper is set and the upper sheet tray selection display LED 44a is turned off (S
52: NO), and the sheet feeding port is in the upper sheet tray 18a (A4
Then, the upper sheet tray selection display LED 44a is turned on and the lower sheet tray selection display LED 44b is turned off (S55). A4 landscape paper selection display LED 44c
And A3 paper selection display LED 44d
Is turned off (S56).

As described above, in the paper feed port switching process, each time the paper feed port setting key 44 is pressed, the paper feed port is changed from the upper sheet tray to the lower sheet tray to the upper sheet tray.
・ It can be switched like so. (C) Intermediate Tray Feeding Routine Next, the intermediate tray feeding routine (Step S6 in FIG. 5)
Will be described with reference to FIG.

During the double-sided copying, the copying for the set number of copies on the first side (front side) has been completed, and the sheet feeding port is set to the intermediate tray 1.
9 (S61: YES), the intermediate tray 1
An off-edge of the sensor SE6 (a change state when changing from the ON state to the OFF state) that detects the discharge of the sheet from the sheet No. 9 is detected (S62: YES), and there is a sheet in the intermediate tray 19, and the sheet in the tray 19 is detected. Sensor S for detecting the presence or absence of
E8 is on (S63: YES), the selected paper is A3, the A4 landscape paper selection display LED 44c is not lit (S64: YES), and the paper present in the intermediate tray 19 is A3. , The sensor SE9 for detecting the sheet size in the intermediate tray 19 is turned on (S65: YE).
In S), the next sheet is supplied from the intermediate tray 19 (S66).

In step S63, the intermediate tray 19
If there is no paper inside (S63: NO), the original sheet feeding port (upper sheet tray 18a or lower sheet tray 18b)
(S67). Then, a sensor S for detecting discharge of the sheet from the intermediate tray 19 is provided.
After a lapse of a predetermined time from the point when the last sheet discharge is detected by E6, the rotation drive of the sheet transporting roller group that has been driven to discharge the sheet to the discharge tray 27 is stopped, and the copy is terminated. The predetermined time is obtained by adding a little extra time to the time required for the paper to be discharged to the discharge tray 27 after the sensor SE6 detects the paper.

In step S64, if the selected sheet is A4 landscape (S64: NO), the next sheet is fed from the intermediate tray 19 (S66). Intermediate tray 1
During the feeding of A3 paper from No. 9 (S64: YES), when the paper in the intermediate tray 19 is A4 landscape (S65: N
O), the paper feed port is switched to the original paper feed port (S67). Then, in the same manner as described above, the copying is terminated after a predetermined time has elapsed from when the sensor SE6 detects the ejection of the last sheet ejected from the intermediate tray 19.

As described above, in the intermediate tray feeding routine, when the feeding of the predetermined number of sheets is completed while the sheet is being fed from the intermediate tray 19, the process of returning to the original sheet feeding port is performed.
Normally, the paper is continuously fed from the intermediate tray 19 until the paper in the intermediate tray 19 runs out. However, when a change in the paper size in the intermediate tray 19 is detected during the paper feeding operation from the intermediate tray 19, the paper feed port is opened. The process of returning to the original paper feed port is performed. Then, in the same manner as described above, the copying is terminated after a predetermined time has elapsed from when the sensor SE6 detects the ejection of the last sheet ejected from the intermediate tray 19. (D) Automatic Ejection Routine Next, the automatic ejection routine (Step S7 in FIG. 5) will be described with reference to FIG.

When the sheet discharged onto the discharge tray 27 and the stacked paper is removed and the off-edge of the sensor SE4 for detecting the presence or absence of the sheet on the discharge tray 27 is detected (S71: YES), the copying operation is being performed. (S72: Y
ES), there is a sheet in the intermediate tray 19, and the sensor SE8
Is turned on (S73: YES), the paper in the intermediate tray 19 is forcibly discharged onto the discharge tray 27 without forming an image on the back surface where no image is formed (S73).
74).

That is, in the automatic discharge routine,
When the user removes all the sheets from the discharge tray 27 after the copy is completed, and the sheets remain in the intermediate tray 19, the sheets in the intermediate tray 19 are discharged. (E) Copy Condition Processing Next, the copy condition processing (step S8 in FIG. 5) will be described with reference to FIG.

When the double-sided copy mode is selected and LE
When D43b is lit (S81: YES), A4 horizontal paper is selected, and the LED 44c is lit (S82: YES), A3 paper remains on the intermediate tray 19 and the sensor SE9 is turned off. If it is in the ON state (S83: YES), the sheet on the side of A4 is placed in the intermediate tray 19
The paper size cannot be adjusted even if inserted into
That is, even if the A4 sheet is carried into the intermediate tray 19 where the A3 sheet remains, and the A4 sheet is to be aligned by the alignment plate 193, the A3 sheet is larger than the A4 sheet, so that the A3 sheet is larger than the A4 sheet. Since the A4 paper cannot be aligned with the above paper, the copy is prohibited and the copy enabled state LED 41a is turned off (S84).

When the double-side copy mode is selected and A3 paper is selected (S81: YE
S, S82: NO), A3 paper in the intermediate tray 19,
Alternatively, even if the A4 paper remains, the A3 paper newly loaded into the intermediate tray 19 for duplex copying can be aligned, so that copying is permitted depending on whether other copy conditions are satisfied. Or prohibited. Similarly, in the two-sided copy mode, when A4 landscape paper is selected and there is no A3 paper in the intermediate tray 19 (S8).
1: YES, S82: YES, S83: NO), since A4 sheets newly loaded into the intermediate tray 19 for duplex copying can be aligned, it is determined whether other copy conditions are satisfied. Copying is permitted or prohibited. When the one-sided copy mode is selected (S81: NO), a single-sided copy desired by the user can be performed regardless of the presence or absence of sheets in the intermediate tray 19.
Copying is permitted or prohibited depending on whether other copy conditions are satisfied. L when copying is permitted
The ED 41a is turned on (S86).

As described above, in the copying condition processing, when two-sided copying is performed, and when paper remains in the intermediate tray 19, the paper size selected by the user and the paper size in the intermediate tray 19 are changed. When the sheets of the selected size are conveyed into the intermediate tray 19 by comparing and judging, when the sheets are aligned and other copy conditions are satisfied, copying is permitted. It is forbidden. In the case where double-sided copying is performed, normally, no paper remains in the intermediate tray 19, and at this time, copying is permitted or prohibited depending on whether or not other copy conditions are satisfied. When a one-sided copy is performed, a copy desired by the user can be performed even if sheets remain in the intermediate tray 19, so that copying is permitted or prohibited depending on whether or not other copy conditions are satisfied. You. (F) Other Processing Other processing (step S9 in FIG. 5) is a step collectively showing processing other than the above. For example, sequence control of a copy operation is performed.

As described above, in the copying machine of the present invention, when a new two-sided copy is performed from a state in which sheets remain in the intermediate tray 19, the sheet size set for newly performing the two-sided copy However, when the size of the paper remaining in the intermediate tray 19 is equal to or larger than that, the paper conveyed into the intermediate tray 19 for performing a new double-sided copy can be aligned. Since the sheet is set from the sheet most recently conveyed into the tray, double-sided copying can be performed in the same manner as when double-sided copying is performed when there is no sheet in the intermediate tray 19 (normal state). The image formed on the second surface can also be made favorable without inclination. That is, in the above case, a user who newly performs duplex copying can perform duplex copying without worrying about whether or not sheets remain in the intermediate tray 19.

Then, the user performs double-sided copying in the same manner as in a normal state, and can obtain only the sheet on which the desired image is formed on both sides from the discharge tray 27. The paper remaining in the intermediate tray 19 is removed from the discharge tray 27 from the time when the double-sided copied paper on the discharge tray 27 is removed.
Is discharged on top. Therefore, when a new two-sided copy is performed from a state in which the sheets remain in the intermediate tray 19 as in the related art, all the remaining sheets in the intermediate tray 19 are discharged before the newly double-sided copied sheet is discharged. The user who newly performs double-sided copying can obtain the desired double-sided copied paper earlier by the time when the paper in the intermediate tray 19 is discharged, and also discharges the paper onto the discharge tray. There is no need to sort necessary paper (paper on which a desired double-sided copy has been made) and unnecessary paper (paper remaining in the intermediate tray 19), which is convenient.

After the double-sided copied paper on the discharge tray 27 is removed, the paper discharged from the intermediate tray 19 onto the discharge tray 27 can be removed again before starting a new copy. Also, there is no need to mix with newly copied paper and to perform sorting work. Further, in a case where a new two-sided copy is performed from a state where the sheet remains in the intermediate tray 19, the sheet remaining in the intermediate tray 19 differs from the sheet size set for newly performing the double-sided copy. Sometimes the second side (back side)
The transfer of the sheet from the intermediate tray 19 to the transfer position for the image formation is performed only until the size of the sheet changes.
The paper left inside is the second in the new duplex copy.
It is not used for image formation on the side, and the user can obtain only the paper on which the desired image is formed on both sides.

In the above description, an analog copying machine has been described as an example. However, the present invention can be applied to an image forming apparatus such as a digital copying machine and a printer other than the analog copying machine.

[0050]

According to the present invention, there is provided a double-sided image forming function, such as an intermediate tray for temporarily storing a sheet having an image formed on one side for forming an image on both sides of the sheet (for example, double-sided copying). An image forming apparatus having an intermediate storage unit, wherein a sheet remains in the intermediate storage unit,
Provided is an image forming apparatus capable of performing only necessary double-sided image formation without newly forming a double-sided image on a sheet remaining in an intermediate tray even when newly starting double-sided image formation. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an analog copying machine according to the present invention.

FIG. 2A is a plan view of an intermediate tray, and FIG. 2B is a cross-sectional view of the intermediate tray.

FIG. 3 is a plan view of an operation panel provided in the copying machine shown in FIG.

FIG. 4 is a schematic block diagram of a control circuit of the copying machine shown in FIG.

FIG. 5 is a schematic flowchart of a main routine showing control contents performed by a computer of the copying machine shown in FIG. 1;

FIG. 6 is a flowchart showing a copy mode key process shown in FIG. 5;

FIG. 7 is a flowchart showing a paper feed port switching process shown in FIG. 5;

FIG. 8 is a flowchart showing an intermediate tray sheet feeding routine shown in FIG. 5;

FIG. 9 is a flowchart showing an automatic ejection routine shown in FIG. 5;

FIG. 10 is a flowchart showing a copy condition process shown in FIG. 5;

[Explanation of symbols]

 S1 Scanning optical system C1, C2 Carriage 10 Illumination lamp M1, M2, M3, M4 Reflection mirror LN Imaging lens PC Photoconductor drum 11 Charging charger 12 Developing device 13 Transfer charger 14 Separation charger 15 Cleaner 16 Main eraser 17 Fixing device 18a 18b Sheet tray 19 Intermediate tray 201, 202, 21, 23, 24, 25 Transport path 22 Sheet transport belt 26 Switching claw SOL1 Solenoid 27 Eject tray 3 Cover 4 Operation panel 41 Start key 41a Copy permission display LED 42 Numeric key 43 Copy mode setting Keys 43a, 43b Copy mode display LED 44 Paper supply port setting key 44a, 44b Selected paper supply port display LED 44c, 44d Selected paper size display LED 45 Display panel 451 DUP warning table Lamp 46 clear key 47 stop key CP computer SE1~SE9 sensor

Claims (1)

[Claims] 1. An image forming apparatus for forming an image on a sheet based on document image information, an image forming means capable of forming an image based on the document image information on a conveyed sheet, and the image forming means Image forming apparatus comprising: an intermediate storage unit that can temporarily store a sheet on which an image is formed on one surface thereof; and a conveying unit that can convey the sheet stored in the intermediate storage unit to the image forming unit. An apparatus, comprising: a sheet size detection unit configured to detect a size of a sheet in the intermediate storage unit; and a sheet size in the intermediate storage unit detected by the sheet size detection unit.
Control means for determining whether or not to convey a sheet from the intermediate storage means to the image forming means, wherein the control means is stored in the intermediate storage means detected by the sheet size detection means. An image forming apparatus configured to cause the conveying unit to convey the sheet stored in the intermediate storing unit to the image forming unit until the size of the sheet changes.