JPH0740149B2 - Duplex copying machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided copying apparatus that forms an image on both sides or one side of a sheet according to a document image.

[Conventional technology]

Conventionally, as this type of apparatus, an automatic document feeder and a double-sided copy unit are incorporated in an analog copying machine, and an operator sets a desired copy mode from an operation unit, for example, single-sided copy or double-sided copy is set, and a copy is performed. When the key is pressed, the original is fed onto the platen by the automatic feeding device, and an image is formed on one side or both sides of the recording medium by a known electrophotographic method on the fed sheet.

[Problems to be solved by the invention]

However, when the originals include both double-sided originals and single-sided originals, the conventional apparatus performs image formation faithfully on the originals. Therefore, the images formed on the sheet include both double-sided copies and single-sided copies, There was a problem that continuous two-sided copy could not be output.

In order to solve this problem, some documents are pre-programmed to read an original to form an image. However, not only is the program troublesome, but if a programming error is made, the desired image is not displayed. Problems were also pointed out from the operational point of view because it was not obtained or unnecessary blank copies were included.

The present invention has been made to solve the above problems, and determines the presence / absence of images on the front and back sides of an original including a double-sided original and a single-sided original to be fed, and feeds the original based on the determination result. By sequentially forming images on the front and back sides of the sheet with images on both sides of a double-sided original and single-sided original, blank pages are automatically packed on both sides of the sheet even if the original contains both double-sided and single-sided originals. It is an object of the present invention to provide a double-sided copying apparatus that can easily obtain a double-sided copying sheet that can be copied by using a continuous page and has a small number of wasted pages.

[Means for solving problems]

A double-sided copying apparatus according to the present invention includes a document feeding unit that sequentially feeds each side of a document including a double-sided document and a single-sided document to an exposure position where the document is exposed, and a document feeding unit that feeds the document to the exposure position. An exposing means for exposing the exposed original, and an image forming means for forming an image on both sides of the sheet, wherein the image of the original exposed by the exposing means is formed on the fed sheet; Discrimination means for discriminating the presence or absence of an image on each side of the document fed to the exposure position, storage means for storing the discrimination result of the discrimination means, and the document feeding means for feeding the document according to the contents of the storage means. The images on the side with the image of the double-sided original or single-sided original are sequentially formed on the front and back sides of the sheet, and double-sided copying is performed from the original including the double-sided original and the single-sided original without a blank page in the middle of each page of the front and back of the sheet. Those having a control means.

[Action]

In the present invention, the control means sequentially forms the images on the front and back sides of the sheet to form the images of the fed double-sided original and the image of the single-sided original according to the determination result of the presence or absence of the image on each side of the original. And double-sided copying without a blank page in the middle of each page of the front and back of the sheet from the original including the single-sided original.

〔Example〕

FIG. 1 is a block diagram showing the configuration of a double-sided image processing apparatus according to an embodiment of the present invention. Reference numeral 1 denotes a document feeding means, which has a reversing mechanism 1a for reversing a document and sequentially loads the placed documents. The image is accurately fed to the platen position of the image reading unit 2, and after the image reading is completed, the document is discharged to a predetermined position. The image reading unit 2 optically scans a document placed on the platen, converts an image into an electric signal by an image pickup device (for example, CCD) (not shown), and modulates an optical signal of a scanner (not shown) of the image forming unit 3. To do. Further, the image reading means 2 includes
A control unit 2a for controlling each unit is provided, and is configured to communicate with each unit via a cable (not shown) via each interface so that processing can be executed in real time. Further, the control section 2a is provided with the image determination means 2b and the conveyance control means 2c of the present invention, and the image determination means 2b preliminarily scans the originals fed from the original feeding means 1 and having one side and both sides mixed. The presence or absence of images on both sides of all scanned and placed originals is determined,
The determination result is stored in the work memory of the control unit 2a. The transport control means 2c is the determination result of the image determination means 2b, that is,
According to the contents stored in the work memory of the control unit 2a, a command for sequentially controlling the conveyance of the document and the conveyance of the recording medium is sent in parallel to the document feeding means 1, the image forming unit 3 and the duplex unit 4. The duplex unit 4 selectively reverses a recording medium (hereinafter, referred to as a recording sheet (sheet)) fed by the sheet feeding unit 5 and image-formed by the image forming unit 3,
The recording paper can be fed to the image forming unit 3 again. The duplex unit 4 is provided with an intermediate tray 4a for temporarily stopping the conveyed recording paper. Reference numeral 5 is a paper feeding means, which is a paper feeding cassette (including manual feed) prepared for each size of recording paper,
It is composed of a paper deck that stores a large amount of recording paper. Reference numeral 6 denotes a sheet discharging unit, which is composed of a sorter, a discharging tray, and the like on which the formed double-sided or single-sided copies are sequentially placed in the image forming unit 3. The image forming section 3 transfers an image onto a recording sheet by a known electrophotographic method according to an electric signal output from the image reading means 2. Further, the image reading means 2 is provided with an operation section for setting the image forming mode, and the operator can easily set the desired mode.

Next, the operation will be described.

With the original set in the original feeding unit 1,
When the operator sets the double-sided mode from the operation unit and presses a copy key (not shown), document scanning for determining the presence / absence of an image on the document is performed. The page original is accurately fed to a predetermined position of the platen of the image reading means 2. Here, the image reading means 2 scans the document on the platen,
The read image signal is output to the image determination means 2b, and the presence or absence of an image is determined. For example, if an image exists, the fact is stored in the work memory of the control unit 2a. Next, the document feeding unit 1 temporarily discharges the document of the last page from the platen, and the reversing mechanism 1a reverses the document surface one page before the last page to be placed on the platen. Next, the document feeding means 1 again feeds the document to the platen. Subsequently, document scanning is started in the same manner as described above, and the presence or absence of an image on the document surface is determined. As a result, for example, when it is determined that the image does not exist, the fact is stored in the work memory of the control unit 2a. Perform this operation for all placed documents,
The presence or absence of an image is stored in the work memory. When all the original scanning is completed, the conveyance control means 2c sends a command to the original feeding means 1 to feed the last page of the original to the platen according to the page sequence stored in the work memory. Next, the control unit 2a outputs a command to convey the recording paper housed in the paper supply unit 5 to the registration position of the image forming unit 3. When the recording paper stops at the registration position, image reading is started, the image signal modulated into an electric signal drives an optical signal generator, for example, a laser of the image forming unit 3, and a laser beam is emitted from a scanner (not shown) to a photoconductor. A latent image is formed by scanning, is developed and fixed by a known method, and the recording paper is conveyed to the intermediate tray 4a of the double-sided unit 4 and temporarily placed. Next, the conveyance control means 2c refers to the page sequence described above and shifts to control of the next page. For example, when there is no image on the next page of the document, the placed document is discharged without being inverted, and the document feeding unit 1 feeds the next document. Here, the conveyance control means 2c gives an instruction to feed the original document that has been waiting on the intermediate tray 4a. Then, it waits for the document to reach the above-mentioned registration position, and when it arrives, the same image formation as described above is executed, and the recording paper after the double-sided copy is discharged to the paper discharge means 6 to prepare for the next image formation. To do. This operation is repeated until the document placed on the document feeding means 1 is finished according to the page sequence.

2, FIG. 3, FIG. 4 (a) to (c), FIG. 5 (a)
~ (C) and Fig. 6 (a) ~ (c), the image presence / absence determining operation of the image determining means 2b shown in Fig. 1 will be described.

FIG. 2 is a configuration block diagram of the image determination means 2b shown in FIG. The structure and operation will be described below.

The image signal V _D read by the above-mentioned image sensor is converted into a 6-bit digital signal by the A / D converter 11, and the latch 12
Latch 13, in synchronization with the sampling clock SCL via
It is sent to the comparator 14 and the latch 15. Comparator 1
At 4, the 6-bit image signals sent from the latches 12 and 13 are compared, and if the new image signal sent from the latch 12 is smaller, a comparator output is output to the AND gate 16. The AND gate 16 sends the comparator output from the comparator 14 to the latch 15 in synchronization with the sampling clock SCL. When the latch 15 receives the comparator output, the image signal sent from the latch 12 is sent to the CPU 18
Send to. In addition to the comparator output and the sampling clock SCL, the AND gate 16 receives the enable signal EN indicating the effective section of the image signal from the image sensor, and displays the comparison result of the image signal in the predetermined section for each main scanning line. latch
It is designed to send from 15 to CPU 18. The CPU 18 can detect the lowest density level of each main scanning line, that is, the background level by taking in the image signal from the latch 15 in synchronization with the main scanning line synchronization signal MS. Similarly, the comparator 22 compares the image signals sent from the latches 12 and 13, and if the new image signal sent from the latch 12 is larger, outputs a comparator output to the AND gate 24. The AND gate 24 sends the comparator output from the comparator 22 to the latch 23 in synchronization with the sampling clock SCL. Upon receiving the comparator output, the latch 23 sends the image signal sent from the latch 12 to the CPU 18. In addition to the comparator output and the sampling clock SCL, the enable signal EN indicating the effective section of the image signal from the image sensor is input to the AND gate 24 to display the comparison result of the image signal in the predetermined section for each main scanning line. The data is sent from the latch 23 to the CPU 18. The CPU 18 can detect the highest density level of each hand scanning line, that is, the image level, by capturing the image signal from the latch 23 in synchronization with the main scanning line synchronization signal MS. Reference numeral 19 is a ROM in which the control program is masked. 20 is a RAM, which functions as a work memory. An operation unit 21 is used to set various modes.

The CPU 18 determines a threshold value for each main scanning line based on the detected background level, and sends the threshold value to the comparator 17 in synchronization with the main scanning line synchronization signal MS. Comparator 17
Then, the image signal from the latch 13 is compared with the threshold value from the CPU 18 to generate the binarized signal V _S. As mentioned above, the level of each pixel after A / D conversion is 6 bits.
_(HEX) is given as "0" for the whitest case, and the threshold and background level for each main scanning line are also given as 0-3F _(HEX) .

If the surface of the document cover (not shown) on the platen side is black or mirror-processed, the image signal of the part that is not the document is black and is not detected as the background level. Therefore, the enable signal EN is set to the maximum main scanning width. There is no problem as. Further, when there is a possibility that a portion other than the original is detected as white by the conveyance belt or the like by the original feeding means 1 or the like,
The enable signal EN is limited to the minimum paper size.

FIG. 3 is a schematic diagram for explaining the image presence / absence determining operation of the image determining means 2b shown in FIG. 1. Reference numeral 31 is an original, X is the main scanning direction, Y is the sub-scanning direction, and X _i , X _j , X _k respectively indicate main scanning lines.

4A to 4C are waveform diagrams for explaining the density balance of the scanning lines X _i , X _j , and X _k , in which the vertical axis represents the density level and the horizontal axis represents the scanning line.

5 (a) to 5 (c) are schematic diagrams for explaining various states of originals. FIG. 5 (a) shows the entire surface of the original 31, and FIG. 5 (b) shows the entire surface of the original 31. In FIG. 6C, the entire surface of the original 31 is white.

6 (a) to 6 (c) are waveform charts for explaining the density balance of the original document shown in FIGS. 5 (a) to 5 (c).

As shown in FIG. 3, let us consider a case where an original document in which a character "A" is drawn in black on a white background is scanned in the X direction (main scanning direction) and the Y direction (sub scanning direction).

An image signal obtained at any main scan line X _i in any main scan line in each scan line, that is, the A / D converter 11
4 (a), the output of the latch 15 becomes W _{Xi and} the output of the latch 23 becomes B _Xi , which are taken into the CPU 18. Similarly, the image signals obtained on the main scanning lines X _j and X _k shown in FIG.
As shown in (c), the output of the latch 15 becomes W _Xj , W _Xk , and the output of the latch 23 becomes B _Xj , B _Xk .
Is taken into. CPU18 compares the output W _X, the output B _X of the latch 23 of the latch 15 to be inputted one after another, among all main scan lines, detects the maximum value B _Xmax minimum W _Xmin and B _X of W _X .
Then, the difference | B _Xmax −W _Xmin | between these two values and a preset constant K are compared as shown in the following formula (1), and | B _Xmax −W _Xmin | ≧ K. (1) When this formula is satisfied, it is determined that the original 31 has “image”. Further, when it is determined that the following expression (2) is established, | B _Xmax −W _Xmin | <K (2) It is determined that “there is no image” on the original 31.

Further, the density level obtained by scanning the black document shown in FIG. 5 (a) is as shown in FIG. 6 (a), in which B _Xmax and W _Xmin are detected. Furthermore, FIG. 5 (c)
The density level obtained by scanning the entire white original shown in Fig. 6 is as shown in Fig. 6 (c), in which B _Xmax and W _Xmin
To detect. According to the conventional method, when there is no image as in the case of a document having a full-color background as shown in FIG. 5 (b), the density level as shown in FIG. 6 (b) depends on the color sensitivity of the image sensor. Is output. In this case, finally detected B _Xmax , W _Xmin
Since both of them are at an intermediate level, it is not possible to judge at least "abnormal image". In this example, since the formula (1) is always used as the criterion for determining the presence or absence of an image, the presence or absence of an image can always be accurately determined for any of the documents shown in FIGS. 5 (a) to 5 (c).

Next, referring to FIGS. 7 and 8 (a) and (b), the first
The operation of the conveyance control means 2c shown in the figure will be described.

FIG. 7 is a sectional view of a double-sided copying machine showing an embodiment of the present invention, which includes a document feeding unit (RDF) 41, an image reading unit 42, an image forming unit 43, a duplex unit 44, a paper feeding unit 45, and a discharge unit. It is composed of a paper section 46. The configuration of each unit will be described below.

The RDF 41 includes a document placing tray 41a, a document feeding roller 41b, a transport roller group 41c, a transport belt 41d, deflection cams 41e to 41g, a transport roller 41h, a transport roller 41i, a partition plate 41j, and a deflection cam 41k. There is. Incidentally, I _a ~I _d shows the paper path, respectively.

The image reading unit 42 has a platen 42a, and the platen 42a
The original 31 placed on is scanned by a scanning system (not shown), and the image signal is processed by the CPU 18.

The image forming unit 43 includes a registration roller 43a, a laser 43b, a scanner 43c, an optical lens 43d, a scanning mirror 43e, a photosensitive drum 43f, a conveyor belt 43g, a fixing device 43h, a deflection cam 43i, a paper discharge roller 43j, and the like. .

The duplex unit 44 includes an intermediate tray 44a, a transport roller 44b, a paper feed roller 44c, a transport roller 44d, and the like. Note that each of V _{a to} V _d represents a paper path.

The paper feed section 45 includes the paper feed cassettes 45a and 45b and the paper deck 4
It is composed of 5c. Note that the paper deck 45c is fed with recording paper from the paper path V _d of the duplex unit 44.

The paper output unit 46 is composed of a paper output roller 46a, a sorter 46b, and a paper output bin 46c, and the paper output bin 46c of the sorter 46b is driven by a driving means (not shown) according to a signal sent from the control unit of the image reading unit 42. The driven recording sheets can be driven to place the discharged recording sheets in the correct page order.

8 (a) and 8 (b) are schematic diagrams for explaining the placed state of the document and the page order of the recording paper. In FIG. 8 (a), "Yes" indicates that an image exists, "No" indicates that the image does not exist. The numbers in the drawings indicate page numbers.

Next, the operation will be described.

As shown in FIG. 8A, the original 31 is placed on the original placing tray 41a in a state where one side and both sides are mixed and the first side, that is, the first page faces upward. There is. In this state, when the copy key of the operation unit (not shown) on the image reading unit (hereinafter referred to as a reader) 42 is pressed, the document feeding roller 41b of the document feeding unit 41 is rotated and the document loading tray 41a The document feed roller 41b is rotated to cause the document 31 placed on the document tray 41a to be at the bottom, that is, the 9th and 10th pages shown in FIG. 8A (the 10th page is the lower side). Send out. The document 31 passes through the paper paths I _a to I _b by the transport roller 41 _c and passes through the platen 4 by the transport belt 41 d.
It is transported onto 2a. The original 31 is accurately stopped on the platen 42a by a paper detection sensor (not shown) attached to each paper path and a timing pulse generator (not shown) attached so as to generate a pulse in synchronization with the roller drive system. It is well known that it is controlled to. When the document 31 stops on the platen 42a (the ninth page faces downward), the reader 42 starts the document scanning as described above. By this document scanning, the image determination means 2b provided in the reader 42 determines the presence or absence of an image. For example, since the 9th page of the manuscript 31 is placed so that "there is an image", the reader 42 "has an image on the front side of the Nth manuscript".
Is stored in the work memory. Reader 42
At the same time when the document presence / absence determination is completed, “document reversal” of the document 31 is transmitted to the document feeding unit 41. In response to the "original reversal" command, the original feeding unit 41 starts to convey the original 31 (9th page downward state) on the platen 42a to the left in the drawing by the conveyor belt 41d. The document 31 is fed to the paper path I by the deflection cams 41e and 41f.
After passing _d , the transport roller 41h once stops passing the deflecting cam 41f. After this, the transport roller 41h
Starts to rotate in the opposite direction to the above, and the deflection cams 41f and 41g are set so that the original 31 faces the paper path I _e . The original 31 is transported to the paper path I _e by the transport roller 41 h and the deflection cams 41 f and 41 g, and when the transport roller 41 c passes the transport roller 41 e, the transport roller 41 e stops. Next, the transport roller 41c
The deflection cam 41 starts rotating in the opposite direction to the previous one.
e, 41 g is passed through the document 31 to the paper path I _c, further conveyor belt 4
With 1d, the ninth page stops on the platen 42a with the page facing upward. Here, the reader 42 starts scanning the original document and also determines whether or not there is an image on the original document 31. In this example, since the image also exists on the 10th page, the reader 42
Information that "there is an image on the back side of the Nth original 31" is stored in the work memory. At the same time that the image determining means 2b completes the determination of the presence or absence of the image on the document, the reader 42 causes the document feeding unit 41 to move.
Send the "manuscript discharge" command to. In response to this "document discharge" command, the document feeder 41 starts to transport the document 31 (the 9th page upward state) on the platen 42a to the left in the drawing by the transport belt 41d. After that, as in the case of the "document reversal" sequence described above, the document 31 is temporarily stopped when passing the deflection cam 41f, and then, while passing the paper path I _e , without being stopped this time, the document 31 is conveyed by the transport roller 41i. Loading tray 4
It is further discharged in the direction of 1a and discharged. When discharged, the ninth,
The original 31 of the 10th page has the 9th page facing up, and
A partition plate 4 is provided between the document 31 left on the document tray 41a and the document 31.
It is separated by 1j. After that, the sequence of document feeding → document reversal → document presence / absence determination → document discharge is repeated, and when the presence / absence of images for the five documents 31 placed on the document tray 41a is completed, the double-sided copy sequence is performed. To execute.

Since the image determination means 2b of the reader 42 determines that the copying should be executed according to the page sequence shown in FIG. 8B by the image presence / absence determination sequence, the conveyance control means 2c uses this page sequence. Depending on the document feeder
Control commands are sent to the printer 41, the printer 43, and the duplex unit 44. First, the reader 42 performs “document feeding” to the document feeding section 41.
Output a command. The document feeding unit 41 detects that the document feeding has already been completed, and once releases the partition plate 41j, the partition plate 41j is put on the document 31 again. That is, the state has returned to the state shown in FIG. At this time, as shown in FIG. 8A, the order of the originals 31 is also such that the last page is placed at the bottom. And the leader
By receiving the "document feed" command from 42, the document at the bottom of the document 31 again, that is, 9 and 10 in FIG.
The page number is fed onto the platen 42a. At this time, original 3
1 has the 9th page facing down, so reader 42
According to the previous image determination, it first determines that the 10th page should be copied.
The command of "document reversal" is issued to 41a. The document feeding unit 41a executes the inversion of the document 31 according to the page sequence described above. Here, the reader 42 outputs a copy start command for making a one-sided copy to the printer 43 for the first time, and also starts document scanning for outputting an image signal.

Upon receiving the copy start command from the reader 42, the printer 43 starts feeding the recording paper from the paper feed cassettes 45a and 45b and the paper deck 45c in which the recording paper of the size specified by the reader 42 is set. The recording paper fed is once fed to the position where the registration roller 43a is arranged and stopped. Then, the registration roller 43 is re-rotated by the image leading edge signal from the reader 42, the recording paper is sent out, and the photosensitive drum
The timing is adjusted with the toner image drawn on 43f. The recording paper on which the toner image has been transferred is conveyed to the fixing device 43h by the conveyor belt 43g, and the toner image is fixed on the recording paper by heat and pressure. Since it is known from the page sequence that the recording paper exiting the fixing device 43h does not need to be copied on the back side, the deflecting cam 43i is used to eject the recording paper.
It is controlled to convey in the direction of 3j. Paper ejection roller 43j
The recording paper discharged from the sorter 4a is conveyed by the conveying roller 46a.
The paper is discharged onto the paper discharge bin 46c of 6b. At this time, the recording paper is such that the tenth page of the document 31 shown in FIG. During the paper discharge process, for example, when the recording paper leaves the fixing device 43h, the printer 43 tells the reader 42
Send the "copy of next recording paper is ready" signal. The reader 42, which has received this signal, has determined that the ninth page of the original 31 should be copied next time, so the reader 42 is again instructed to "invert the original" and the above-mentioned sequence is executed. ,
Execute original reversal. When the document inversion is completed, the reader 42 outputs a copy start command for making a double-sided copy to the printer 43, and at the same time starts the document scanning for outputting the image signal. The printer 43 executes copying in the same sequence as the above, but the recording paper on which the ninth page of the original 31 has been copied by the double-sided copy command from the reader 42 leaves the fixing device 43h and then the deflection cam 43i. By paper path V _a
Head to. The recording paper is further passed through the upper path V by the conveyance roller 44c.
After passing through _b , it is placed on the intermediate tray 44a. At this time, the surface of the recording paper on which the image is formed, that is, the ninth page of the document 31 is on the upper side. While the recording paper is being conveyed to the intermediate tray 44a, for example, when it exits the fixing device 43h, the printer 43 transmits a “copyable on back side” signal to the reader 42. Upon receipt of this signal, the reader 42 judges that the seventh page of the original 31 should be copied next (page sequence), and then causes the original feeder 31 to deflect the original 31 currently on the platen 42a to the original feeding unit 41. 41e and 41k eject the paper to the original tray 41a through the paper paths I _c and I _e , and
1, that is, the document 31 at the bottom on the document tray 41a
Are fed onto the platen 42a. In this state, since the seventh page of the document 31 is on the lower side, the reader 42 immediately outputs a copy start command from the intermediate tray 44a to the printer 43. The recording paper fed from the intermediate tray 44a is conveyed by the conveyance roller 44d through the paper paths V _c and V _d to the position where the registration roller 43a is arranged, and is temporarily stopped. Thereafter, the same sequence as described above is performed, and the paper is discharged onto the paper discharge bin 46c of the sorter 46b. At this time, the recording paper on the paper discharge bin 46c is discharged with the 10th and 7th pages facing upward.

In the same manner, the originals 31 placed on the original placing tray 41a of the original feeding unit 41 are sequentially processed from the bottom, and a double-sided copy with no missing pages is output. Also, Sorter 46b
In the case of using, when the required number of copies of the double-sided copied recording paper have been collected in the discharge bin 46c, the next double-sided copying is started.

In the above embodiment, the case where the document feeding section 41 independently controls the feeding or discharging of the document 31 has been described.
Paper feed and paper discharge may be processed in parallel. Further, in the above embodiment, the entire surface of the original 31 is scanned to determine the presence or absence of an image.
When the presence of an image can be detected during scanning of the document 31, the document scanning may be terminated and the process may move to the next step operation.

〔The invention's effect〕

As described above, according to the present invention, the images on the side with the images of the fed double-sided document and the single-sided document are sequentially formed on the front and back sides of the sheet according to the determination result of the presence or absence of the image on each side of the document. , Double-sided originals and single-sided originals can be copied on both sides of the sheet without any blank pages in the middle of each page of the sheet. A page can be packed and copied, and a double-sided copy sheet with continuous pages and few wasted pages can be easily obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a double-sided image processing apparatus showing an embodiment of the present invention, FIG. 2 is a block diagram of an image judging means shown in FIG. 1, and FIG. 3 is an image shown in FIG. FIG. 4A is a schematic diagram for explaining the image presence / absence determination operation of the determination means.
5A to 5C are waveform diagrams for explaining the density balance of scanning lines, FIGS. 5A to 5C are schematic diagrams for explaining various document states, and FIGS. 6A to 6C are fifth diagrams. Figures (a)-(c)
7 is a waveform chart for explaining the density balance of each document shown in FIG.
FIG. 1 is a sectional view of a double-sided copying machine showing an embodiment of the present invention,
FIGS. 8A and 8B are schematic diagrams for explaining the placed state of the original and the page order of the recording paper. In the figure, 1 is a document feeding unit, 1a is a reversing mechanism, 2 is an image reading unit, 2a is a control unit, 2b is an image determination unit, 2c is a conveyance control unit, 3 is an image forming unit, 4 is a double-sided unit, and 4a. Is an intermediate tray, 5 is a paper feeding means, and 6 is a paper discharging means.

Claims (1)

[Claims] 1. A document feeding unit for sequentially feeding each side of a document including a double-sided document and a single-sided document to an exposure position for exposing the document, and a document fed to the exposure position by the document feeding unit. An exposing means for exposing, an image forming means for forming an image on both sides of the sheet, and an image forming means for forming an image of the original document exposed by the exposing means on the fed sheet, and the exposing position. Discriminating means for discriminating the presence or absence of an image on each side of the document to be fed, storage means for storing the discrimination result of the discriminating means, and a double-sided document fed by the document feeding means in accordance with the contents of the storage means. A control unit that sequentially forms images on the front and back sides of the sheet with the image of the single-sided original, and performs double-sided copying without a blank page in the middle of each page of the front and back of the sheet from the original including the double-sided original and single-sided original. Duplex copying apparatus which is characterized in that.