CN1307493C - Two-sided image forming device - Google Patents

Abstract

A one-side image forming apparatus of the present invention is provided with a first sheet-transferring path, for use in one-side image formation, for transferring, to a printed sheet storage section via an image transcribing section, a sheet supplied from an unprinted sheet storage section; and a second sheet-transferring path, connected to the first sheet-transferring path, for supplying a tuned-over one-side printed sheet to the image transcribing section, the two-image forming apparatus being controlled so that a plurality of sheets are transferred concurrently in an overall sheet-transferring path when performing two-side image forming operation, the overall sheet-transferring path including the first sheet-transferring path and the second sheet-transferring path. With this arrangement, it is possible to attain a significant improvement in process efficiency.

Description

double-sided image forming device

technical field

The present invention relates to a double-sided image forming apparatus that forms images on both sides of paper, and more particularly, to a double-sided image forming apparatus that achieves an overall high-speed image forming process.

Background technique

Conventionally, as an image forming apparatus for duplex printing, for example, JP-A-11-341231 (publication date: December 10, 1999) is known. As shown in FIG. 1 of this publication, the double-sided image forming apparatus is provided with a transfer drum 19 for transferring the image read by the image reading section 1a onto the paper P. In the case of , the paper conveyed from the paper storage unit 5 to the main conveyance path (an example of the first paper conveyance path) 6 passes through the transfer unit near the above-mentioned transfer drum 19 to transfer the image onto the paper surface. The transferred image is fixed by the fixing roller 23 . The paper P on which the image is fixed is held by the reverse roller 10 rotating forwardly until its rear end is sent out.

Then, by reversing the reversal roller 10, the paper enters the sub-transport path 8 (an example of the second paper transport path), is sent to the transport roller 11 provided in the sub-transport path 8, and then enters the main transport path 6 again. By the inversion of the inverting roller 10 described above, the paper entering the sub-transport path 8 passes from there into the main conveying path 6, whereby the front and back of the paper are reversed. Therefore, at this time, the surface of the paper facing the transfer drum 19 is the back side of the paper P, so the image can be transferred to the back side of the paper P passing through the main transport path 6 .

In this way, after the image transfer to the front and back of the paper P is completed, the paper P is discharged to the paper discharge tray 12 by the normal rotation of the reverse roller 10 .

The double-sided image forming apparatus described in the above-mentioned Japanese Patent Laid-Open No. 11-341231 has the above-mentioned configuration, and performs double-sided printing by continuous conveyance of paper, so that the processing time can be shortened, and since the auxiliary conveyance path that does not take up space is used, the The miniaturization of the device can be realized.

However, in the above-mentioned double-sided image forming apparatus, since only one sheet of paper can be passed through the above-mentioned two conveyance paths of the main conveyance path 6 and the sub-transport path 8 during the double-sided printing process of one sheet of paper, it is impossible to achieve double-sided printing. Parallel double-sided printing of multiple pages, in this sense, has the problem of low printing efficiency.

Therefore, when double-sided printing is performed, printing efficiency can be improved by conveying multiple sheets of paper in parallel. Japanese Patent Application Laid-Open No. 2001-171884 (publication date: June 26, 2001) discloses an image forming apparatus that causes a subsequent sheet to enter a reversing path while reversing and conveying a preceding sheet in the reversing path . In this method, the timing at which the subsequent sheet enters the inversion path during inverting conveyance of the preceding sheet is after the preceding sheet enters a guide for guiding the inverted sheet again into the conveyance path.

However, in this method, the printing efficiency is not high, so a method is being sought to efficiently transport multiple sheets of paper without causing paper jams during double-sided printing, which involves complex paper transport including paper inversion. double-sided image forming device.

Contents of the invention

An object of the present invention is to provide a double-sided image forming apparatus having a main conveyance path and a sub-transport path, and capable of significantly improving processing efficiency.

In order to achieve the above object, the double-sided image forming apparatus of the present invention is provided with: a first paper conveying path for single-sided image formation, so that the paper sent out of the unprocessed paper storage part passes through the image transfer part, and then sent to the image processing complete Paper storage section; the second paper conveying path, which is connected with the above-mentioned first paper conveying path, turns over the surface and back of the paper that has been image-processed on one side, and then sends it to the above-mentioned image transfer section; along the above-mentioned second paper intermediate rollers provided in the conveyance path; and registration rollers for synchronizing the timing of paper conveyance to the above-mentioned first paper conveyance path. The first paper conveyance path and the second paper conveyance path are arranged so that multiple sheets of paper can be conveyed across the entire paper path constituted by the first paper conveyance path and the second paper conveyance path during the double-sided image forming operation. Simultaneously travel along the path. The rotation of the above-mentioned intermediate roller is synchronized with the restart rotation of the above-mentioned registration roller.

Thus, multiple sheets of paper pass through from the first paper conveying path to the second paper conveying path at the same time, which significantly improves the processing efficiency compared with the prior art where only one sheet of paper can be processed at the same time.

Other objects, features, and advantages of the present invention will be fully understood through the following description. Furthermore, advantages of the present invention will become apparent by the following description with reference to the accompanying drawings.

Description of drawings

1 is a schematic cross-sectional view mainly illustrating in detail the structure of an image forming section of a double-sided image forming apparatus according to one embodiment of the present invention.

FIG. 2 is a schematic sectional view similar to FIG. 1 for explaining the processing procedure.

FIG. 3 is a schematic cross-sectional view similar to FIG. 1 for explaining the processing procedure.

FIG. 4 is a schematic cross-sectional view similar to FIG. 1 for explaining the processing procedure.

Fig. 5 is a schematic sectional view similar to Fig. 1 for explaining the processing procedure.

FIG. 6 is a control block diagram of the double-sided image forming apparatus.

FIG. 7 is a diagram illustrating the operation of each part of the double-sided image forming apparatus.

Detailed ways

Hereinafter, a first embodiment of the present invention will be described using the drawings. FIGS. 1 to 5 are schematic cross-sectional views and diagrams showing a process sequence of an image forming section of a double-sided image forming apparatus according to an embodiment of the present invention, and FIG. 6 is a control block diagram of the double-sided image forming apparatus. FIG. 7 is a diagram showing operations of various parts of the double-sided image forming apparatus.

As shown in FIG. 1 , a double-sided image forming apparatus 1 according to this embodiment is composed of an image reading unit 4 and an image forming unit 9 which will be described later.

The image reading unit 4 includes a CCD sensor 2 that reads an image while inverting and conveying a document D discharged from the document tray TR1 by rollers 3 , while reaching the document discharge tray TR2 .

The above-mentioned image forming section 9 is mainly composed of the following parts: a transfer drum (image transfer device) 5, which forms an electrostatic latent image according to the image information read by the above-mentioned CCD sensor 2; An example of ) 7, the paper discharged from the unprocessed paper storage part T1 storing the transfer paper is conveyed to the image-processed paper storage part T2 via the transfer part and the fixing roller 6 near the above-mentioned transfer drum 5; The reversing part (reversing device) R3 is composed of reversing rollers, which are arranged before the above-mentioned image-processed paper storage part T2 of the above-mentioned main conveying path 7; In front of the upstream side of the drum 5; the sub-transport path (an example of the second paper transport path) 8 branches off from the main transport path 7 on the upstream side of the reversing portion R3, and merges with the main transport path 7 on the upstream side of the registration roller R1. the diverging claw C1 is provided on the diverging part of the above-mentioned main conveying path 7 and the sub-transporting path 8; The registration roller R1 is a device for adjusting the start timing of paper conveyance to the main conveyance path 7 so that the image position on the transfer drum 5 coincides with the transfer position on the paper.

In addition, a first paper sensor S1 is provided on the upstream side of the main transport path 7 immediately adjacent to the registration roller R1, and a second paper sensor S2 is provided on the side of the reversing part R3 immediately after the image-processed paper storage part T2, A third sheet sensor S3 is provided on the sub-transport path 8 immediately downstream of the intermediate roller R2.

Of course, a main charger around the transfer drum, a cleaning device, and other image forming components are provided in the image forming unit 9 , but detailed description thereof will be omitted here for simplification of description.

The above constituent elements are connected as shown in FIG. 6 . That is, in order to perform paper conveyance control described later, the first to third paper sensors S1 to S3 are connected to the input unit of the control unit 12 provided with a CPU, a ROM for storing programs, and a RAM for temporarily storing data. The drive unit R1a, the drive unit R2a of the intermediate roller R2, the drive unit R3a of the reversing unit R3, the drive unit C1a of the diverging claw C1, and the drive unit C2a of other image forming elements are respectively connected to the output unit of the control unit 12.

The processing procedure of the control unit 12 used in the double-sided image forming process of the double-sided image forming apparatus 1 according to the present embodiment will be described below with reference to FIGS. 1 to 7 .

First, a general one-side image forming process will be described. In this case, a signal from the CCD sensor 2 is received to form an electrostatic latent image on the peripheral surface of the transfer drum 5, and the electrostatic latent image is developed with toner by the developing section, and is then imaged by the rotation of the transfer drum 5. Ship to Transcription Department. Corresponding to this image formation, the control unit 12 stops (OFF) the registration roller R1 and the intermediate roller R2, and then rotates the reversing unit R3 in the normal direction, as described in the column “Single-sided printing” in FIG. 7 . In this state, the control unit 12 drives the paper feed rollers of other image forming elements, and supplies the paper in the unprocessed paper storage unit T1 to the main conveyance path 7 . When the paper passes the first paper sensor S1 , a paper detection signal from the first paper sensor S1 is transmitted to the control section 12 . When the paper detection signal from the first paper sensor S1 is transmitted, the control unit 12 starts the rotation of the registration roller R1 after a predetermined time. As a result, the paper passes through the transfer section near the transfer drum 5, and the above-mentioned image is transferred onto the paper.

When the paper passes through the fixing roller 6, the transferred image is fixed. At this time, the control part 12 deflects the diverging claw C1, so that the paper being conveyed flows to the reversing part R3, thereby, the paper reaches the reversing part R3 which continues to rotate forward, is conveyed by the reversing part R3, and is discharged until the image processing is completed. Paper storage section T2. When the sheet discharge ends, the control section 12 stops the rotation of the registration roller R1 and the reversing section R3.

So far, the one-sided printing process is completed. If there are multiple pages, repeat the above sequence.

The processing for double-sided printing will be described below. In this embodiment, the images are read in the order of the first page, the third page, the second page, and the fourth page of the document (each document image is formed on the surface of the first page P1 and the surface of the second page P2). , the back of the first page P1, the back of the second page P2). Such a document reading order can be realized by various methods. For example, after the first page is read, instead of reading the second page, it passes through the reading section and retreats, then the third page is conveyed and read, and when the reading of the third page is completed, the The document of the third page is retracted, the document of the second page is conveyed to the reading unit, and after the reading of the second page is completed, the reading of the fourth page is performed. For example, the method described in Japanese Patent Application Laid-Open No. 11-341231 is also an example, but since the feature of the present invention is not a method of reading a document but a method of forming an image, a detailed description of the method of reading a document will be omitted.

In the case of double-sided printing, a signal from the CCD sensor 2 is received, and an image corresponding to the image of the first page of the original (the image printed on the front side of the first page of paper P1) is formed on the peripheral surface of the transfer drum 5. The electrostatic latent image is then developed with toner by the developing section, and is conveyed to the transfer section by the rotation of the transfer drum 5 . Corresponding to this image formation, as described in step A of the column "Double-sided printing" in FIG. ON). In this state, the control unit 12 drives the paper feed rollers among the other image forming elements, and supplies the first sheet P1 in the unprocessed paper storage unit T1 to the main transport path 7 . When the first paper P1 passes the first paper sensor S1 , a signal from the first paper sensor S1 is transmitted to the control section 12 . When the paper detection signal of the first paper sensor S1 is transmitted, the control unit 12 starts rotation of the registration roller after a predetermined time. As a result, the paper P1 passes through the transfer unit near the transfer drum 5 , and the image of the above-mentioned first page of the document is transferred onto the surface of the paper P1 . When the transfer is completed, the control unit 12 stops the registration roller R1.

When the paper P1 passes through the fixing roller 6, the transferred image is fixed. At this time, the control unit 12 deflects the diverging claw C1 so that the conveyed paper P1 flows toward the reversing part R3, thereby the paper reaches the reversing part R3 which continues to rotate forward, and is transported to the image-processed paper storage part T2 by the reversing part R3. The paper P1 that has passed through the reversing portion R3 is detected by the paper sensor S2.

The above-mentioned reversing part R3 is a pair of rollers that can be forward and reversed provided on the above-mentioned main conveying path 7 immediately before the above-mentioned image-processed paper storage part T2, and the reversing part R3 can send the image-processed paper to the above-mentioned auxiliary conveying path 8. As shown below, the reversing unit R3 can convey the image-processed paper to the above-mentioned sub-transportation path by a single reversing unit, and can send it to the image-processed paper storage unit T2, so it is advantageous for simplification of the apparatus.

Then, as described in step B, after a predetermined time has elapsed since the control unit 12 received the paper detection signal from the paper sensor S2, the reversing unit R3 is reversed (thus, the paper at the rear end is held by the reversing unit R3 The conveying direction of P1 is reversed), and at the same time, the diverging claw C1 is deflected, so that the sheet P1 from the reversing portion R3 flows toward the sub-conveying path 8 . In addition, the intermediate roll R2, which has been stopped, is started to rotate. The paper P1 in FIG. 1 shows the position of the paper P1 in a state where the reversing portion R3 is reversed.

Then, the paper P1 is sent out by the reversing portion R3 so as to enter the sub-transport path 8 . When the end portion of the paper P1 on the advancing direction side reaches the intermediate roller R2 located in the middle of the sub-transport path 8 and starts to rotate, it is gripped by the intermediate roller R2 and transported in the sub-transport path 8 . After the front end of the paper P1 passes the intermediate roller R2, the paper sensor S3 provided on the immediately downstream side of the intermediate roller R2 detects the passing of the paper P1. When receiving the paper detection signal from the paper sensor S3 , the control unit 12 stops the rotation of the intermediate roller R2 after a predetermined time, thereby stopping the conveyance of the paper P1 . Paper P1 of FIG. 2 shows the paper position in this state. As a result, the paper entering the sub-transportation path 8 is stopped in the sub-transportation path 8 with its rear end (end portion on one side in the advancing direction) gripped by the intermediate roller R2. At this time, the reversing portion R3 is rotated forward.

Before and after the paper P1 is sent out by the reversing unit R3 , the image of the third original (transcribed on the surface of the second paper P2 ) is sent out from the CCD sensor 2 and developed on the transfer drum 5 . Corresponding to the reading timing of the third page, the control unit 12 drives the paper feed rollers in other image forming elements, and supplies the second paper P2 in the unprocessed paper storage unit T1 to the main conveyance path 7 . When the paper P2 passes the first paper sensor S1 , a signal from the first paper sensor S1 is transmitted to the control section 12 . When the paper detection signal from the first paper sensor S1 is transmitted, the control unit 12 temporarily rotates the registration roller R1, and then stops the rotation after a predetermined time, and rotates the paper P2 while the registration roller R1 holds the front end of the paper P2. P2 stops within the main transport path 7 . Fig. 2 shows this state.

In this way, in the double-sided image forming apparatus, when the double-sided image forming operation is performed, in the paper conveyance path including the above-mentioned main conveyance path 7 and the above-mentioned sub-transport path 8, multiple sheets of paper can be advanced at the same time, so the improvement is significantly improved. The efficiency of the double-sided image forming process is improved.

When it is confirmed that both the paper P1 and the paper P2 are held by the intermediate roller R2 and the registration roller R1, that is, when both the sensor S3 and the sensor S1 transmit the paper detection signal, and the intermediate roller R2 and the registration roller R1 are in a stopped state, the signal is received. The control unit 12 restarts the rotation of the intermediate roll R2 and the registration roll R1. As a result, the second sheet of paper P2 passes through the transfer section near the transfer drum 5 , and the image of the above-mentioned third page of the original is transferred onto the surface of the second sheet of paper.

When the second sheet P2 passes through the fixing roller 6, the transferred image is fixed. At this time, the control unit 12 deflects the diverging claw C1 so that the sheet being conveyed flows toward the reversing unit R3. As a result, the paper P2 reaches the reversing unit R3 where the forward rotation continues, and is conveyed to the image-processed paper storage unit T2 by the reversing unit R3. When the second sheet of paper P2 passes over the reversing portion R3 and is detected by the paper sensor S2, the control unit 12 reverses the reversing portion R3 after receiving the signal from the paper sensor S2 and switches the diverging claws at the same time. C1. However, this driving may be omitted when switching of the branch claw C1 described above is unnecessary.

At this time, synchronously with the resumption of rotation of the above-mentioned registration roller R1, the intermediate roller R2 rotates, the first sheet P1 passes through the sub-transport path 8, and then reaches the registration roller R1, and the registration roller is moved by the sensor S1 as in FIG. R1 stops spinning. The states of the paper P1 and the paper P2 subjected to the above conveying and printing processing are shown in FIG. 3 .

In this way, when the sheets are conveyed from the state of FIG. 2 to the state of FIG. 3 , it is necessary not to overlap the first sheet P1 and the second sheet P2. To this end, first, assuming that the length of the largest paper sheet in the conveyance direction among the paper sheets that can be supplied to the double-sided image forming apparatus is L1, the length measured along the above-mentioned sub-transport path 8 from the above-mentioned paper sensor S3 to the above-mentioned registration roller R1 If the distance between them is set to L2, the relationship of L1<L2 must be guaranteed. If this relationship is not guaranteed, during the synchronous rotation of the above-mentioned registration roller R1 and the intermediate roller R2, the front part of the first sheet P1 conveyed by the intermediate roller R2 and the second sheet sent out from the paper feeding part T1 will be separated. Paper P2 will overlap.

It is also important that the rear end of the first sheet P1 sent out through the reversing portion R3 does not interfere with the leading end of the second sheet P2 flowing to the reversing portion R3 through the main conveyance path 7 . For this reason, if the distance from the registration roller R1 to the inversion portion R3 measured along the main conveyance path 7 is L3, it is necessary to set L1<L3.

Also, if the largest usable paper cannot be accommodated in the sub-transport path 8, the first sheet P1 and the second sheet P2 will interfere at the part of the diverging claw C1 or the registration roller R1. Therefore, it is necessary to prevent this interference, and the distance between the part located on the downstream side of the transfer section and the sub-transport path from the intersection of the sub-transport path and the registration roller R1 measured along the transport path (that is, the total length of the auxiliary transport path 8) is set to L4, then L1<L4 should be set. As long as the above conditions are satisfied, interference between the conveyed sheets can be avoided.

In this way, the second sheet P2 reaches the forward-rotating reversing portion R3, and is conveyed to the image-processed paper storage portion T2 by the reversing portion R3. The paper P2 passing through the reversing part R3 is detected by the paper sensor S2. Like the first paper P1 shown in FIG. . Thus, as shown in step C, the second sheet P2 is sent into the sub-transport path 8 . The front end of the fed paper P2 is detected by the paper sensor S3, and the intermediate roller R2 stops, whereby the paper P2 stops in the sub-transport path 8 while being held by the intermediate roller R2.

In this way, while the first sheet of paper remains in the sub-transport path 8, the next second sheet of paper P2 arrives at the reversing portion R3. The paper is conveyed, so the efficiency of the image forming process is remarkably improved.

Among them, the first sheet P1 is held by the registration roller R1 and stopped in the sub-transport path 8, and the second sheet P2 is held by the intermediate roller R2. At this time, like the conveyance from FIG. 2 to FIG. 3, when the paper sensor S1 and the paper sensor S3 detect that the first sheet P1 and the second sheet P2 are held by the rollers R1 and R2, respectively, the The control unit 12 restarts the rotation of the registration rollers, whereby the first sheet of paper P1 passes through the transfer section near the transfer drum 5, and the image on the surface of the second page of the document is transferred to the back of the sheet of paper P1.

When the first sheet P1 passes through the fixing roller 6 , the transferred image is fixed and then conveyed to the image-processed sheet storage unit T2 . At this time, corresponding to the conveyance of the first sheet P1, the second sheet P2 stopped at the intermediate roller R2 is also passed through the secondary conveyance by the rotation of the intermediate roller R2 synchronously with the resumption of rotation of the registration roller R1 as described above. Passage 8, and then reaches the positioning roller R1 (refer to FIG. 4).

In step D, corresponding to the image forming timing, the second sheet is sent to the transfer section by the rotation of the registration roller R1, so that the image of the fourth original is transferred on the back side of the second sheet, and is then It is discharged to the image-processed paper storage section T2. The states of paper P1 and paper P2 that have undergone the above conveying and printing processing are shown in Fig. 5. The images of the first and second pages of originals are printed on the front and back of the paper P1, and then discharged to the image processing completed paper storage Department T2.

If the paper is an even-numbered page, repeat steps A to D shown in FIGS. 1 to 5 and 7 above to perform double-sided printing on all the papers.

If the paper is odd-numbered, the control unit 12 switches the diverging claws C1 after repeating the steps A to D more than once, and after the above-mentioned FIG. 5 or step D is completed. Then, the control unit 12 sends out the last paper (odd-numbered pages) from the above-mentioned unprocessed paper storage unit T1 to the main transport path 7, where the one-sided image transfer process is performed by the above-mentioned transfer unit, and the single-sided image transfer process is completed. The paper to be fixed is sent out from the main conveyance path 7 to the sub conveyance path 8 via the switched diverging claw C1. Then, the control unit 12 switches the diverging claw C1 again. Then, the paper that has entered the secondary conveyance path 8 is not stopped by the intermediate roller R2, but is passed through the main conveyance path 7 again. The image processing is completed in the paper storage section T2. Thereby, the double-sided printing on the last odd-numbered sheet is completed. At this time, only the last sheet of paper travels through the entire conveyance path.

In the above-described embodiment, the paper conveyance drive units of the main conveyance path 7 , the sub-transport path 8 , and the reversing portion R3 are independently driven by different drive sources. Thereby, it is possible to freely control the conveyance and stop of the paper in each path 7, 8 or the reversing part R3, and also independently change the speed as needed, so the degree of freedom of control is increased. Of course, a part or all of the above-mentioned drive units may also be constituted by a common drive unit. The cost of the drive system can be reduced by using the structure of the common drive unit. Also, as described above, the distance between the rollers is determined based on the maximum length of the paper so that the paper does not interfere, thereby avoiding the interference of the paper when the paper conveying speed is constant at all times.

The present invention is preferably configured such that the first paper conveyance path has a reversing device before the image-processed paper storage section, and the image-processed paper is delivered to the second paper conveyance path by means of the reversing device.

In the double-sided image forming apparatus described above, it is reasonable to set the number of sheets traveling through the entire sheet conveyance path to two.

The specific structure of the above-mentioned double-sided image forming device preferably has:

The first image processing apparatus passes the first paper taken out from the unprocessed paper storage part through the first paper conveyance path, performs single-sided image processing by the image transfer part, and then conveys it to the reversing device, using The reversing device reverses the conveying direction to the direction of the second paper conveying path;

The second image processing apparatus sends out the first paper whose conveying direction is reversed by the reversing device to the second paper conveying path, and conveys the second paper taken out from the unprocessed paper storage unit through the first paper. path, after the single-sided image processing is performed by the image transfer unit, it is transported to the above-mentioned reversing device, and the conveying direction is reversed to the direction of the second paper conveying path by the reversing device;

The third image processing device sends the first paper located in the second paper conveying path from the second paper conveying path to the first paper conveying path, performs image processing on the back side, and then conveys the first paper through the turning device until the image processing is completed. In the paper storage unit, on the other hand, the second paper whose conveying direction is reversed by the reversing unit is sent out to the second paper conveying path;

and a fourth image processing device that sends out the second paper conveyed to the second paper conveying path from the second paper conveying path to the first paper conveying path, where after image processing is performed on the back side, it is conveyed via a reversing device to the image-processed paper storage section. The above applies to the case where the paper is an even number of pages.

In addition, there may be a fifth image processing device, immediately after the fourth image processing device performs image processing on the back side of the second paper, after the third paper is sent out from the unprocessed paper storage part to the first paper conveyance path, Wherein, after the above-mentioned image transfer section performs the one-sided image transfer process, the transfer direction is reversed by means of the above-mentioned turning device R3, and then it is sent out from the first paper transfer path to the second paper transfer path, and it passes through the second paper transfer path again. A paper conveyance path in which the backside is subjected to image processing, and is conveyed to the image-processed paper storage unit via the reversing device. The above applies to the case of odd-numbered sheets of paper.

In addition, the above structure can be expressed as follows.

In the double-sided image forming apparatus of the present invention, it is preferable that the second paper to be image-processed next to the first paper is taken out from the above-mentioned unprocessed paper storage part, passes through the first paper conveying path, and ends with the help of the above-mentioned reversing device. Until the conveying direction is reversed, the reversing device reverses the conveying direction of the first paper, and then sends it out to the second paper conveying path. In addition, from the time when the first paper that has been subjected to image processing on one side and sent out to the second paper conveyance path is subjected to image processing on the back side of the paper in the first paper conveyance path, until it is sent to the image-processed paper storage section, The reversing device reverses the conveying direction of the second paper, and sends it out to the second paper conveying path. By repeating the above operation one or more times, image processing can be efficiently performed on even-numbered sheets.

In addition, it may be controlled so that after the above-mentioned operation, that is, after the second paper is sent out to the second paper conveying path, the back side of the paper is image-processed in the first paper conveying path, and is sent to the above-mentioned image processing After the paper storage section is completed, only one third paper to be image-processed next travels in the entire paper transport path. When image processing is performed on odd-numbered sheets, image processing can be efficiently performed by performing the above operation last.

The first paper conveying path, the second paper conveying path, and the paper conveying drive units of the inverting device may be independently driven by different driving sources.

The first paper conveying path, the second paper conveying path, and the paper conveying drive units of the above-mentioned reversing device can operate according to the presence or absence of paper detected by the paper detection device provided in each path or reversing device.

The specific structure of the above-mentioned paper detection device is preferably that the above-mentioned paper detection device at least includes a first paper detection device arranged before the upstream side of the above-mentioned registration roller, and the first paper detection device detects that when the paper is conveyed in the entire conveying path When another sheet of paper passes on the upstream side, the registration rollers are stopped at predetermined timing.

In addition, the paper detection device further includes a second paper detection device disposed in the second paper conveyance path, and when the second paper detection device detects that paper passes through the second paper conveyance path, the The detected paper stops at this position, and when the above-mentioned first paper detection device and the second paper detection device detect the paper at the same time, the rotation of the above-mentioned registration roller and the paper in the above-mentioned second paper conveyance path are made according to the predetermined timing. The delivery restarts.

In this way, by providing and operating the above-mentioned paper detection device, the paper conveyed from the unprocessed paper storage part to the image-processed paper storage part through the main conveyance path and the image-processed paper storage part from the image-processed paper storage part through the sub-transport path to the Sheets conveyed by the main conveyance path are conveyed at the same time without interference, thereby significantly improving processing efficiency.

The specific implementations or examples described in detail in the present invention are only to illustrate the technical content of the present invention, but the present invention is not limited to the above-mentioned specific examples and is interpreted in a narrow sense. Within the spirit of the present invention and the scope of the claims, Various changes can be made thereto.

Claims (16)

1. A double-sided image forming device, comprising: The first paper conveying path (7) for single-sided image formation allows the paper sent out from the unprocessed paper storage unit (T1) to pass through the image transfer unit (5), and then sent to the image-processed paper storage unit (T2); The second paper conveying path (8) is connected with the above-mentioned first paper conveying path (7), so that the surface and back of the paper that has been image-processed on one side are reversed, and then sent to the above-mentioned image transfer unit (5); an intermediate roller (R2) provided along the above-mentioned second paper conveyance path (8); and Registration rollers (R1) for synchronizing the timing of feeding paper to the above-mentioned first paper feeding path (7), Wherein, the above-mentioned first paper conveying path (7) and the above-mentioned second paper conveying path (8) are configured such that when a double-sided image forming operation is performed, multiple sheets of paper can pass through the above-mentioned first paper conveying path (7) and the above-mentioned second paper conveying path (8). Advance simultaneously in the whole paper conveying path (7,8) that above-mentioned second paper conveying path (8) constitutes, The rotation of the above-mentioned intermediate roller (R2) is synchronized with the restart rotation of the above-mentioned registration roller (R1). 2. The double-sided image forming apparatus according to claim 1, wherein the first paper conveyance path (7) has a reversing device (R3) before the image-processed paper storage part (T2), and the reversing device (R3) The paper that has been image-processed on one side is delivered to the above-mentioned second paper conveying path (8). 3. The double-sided image forming apparatus according to claim 2, further comprising a paper sensor (S3) for detecting the passing of paper in the second paper conveying path (8), and the paper is passed through the first paper conveying path (7). ), which has been subjected to single-sided image processing, and then turned over and conveyed in the second paper conveying path (8), when the paper sensor (S3) detects that the paper passes, the detected paper stops at The position, and restart the delivery according to the specified timing. 4. The double-sided image forming apparatus according to claim 2, wherein a part of the first paper transport path (7) from the unprocessed paper storage unit (T1) to the image transfer unit (5) is connected to the second paper transport path (7). At the connecting part of the paper conveyance path (8), in order to adjust the position of the image transferred by the image transfer unit (5) on the paper, there is also a positioner for adjusting the timing of starting the transfer of the paper to the image transfer unit (5). Roller (R1). 5. The double-sided image forming apparatus according to claim 1, wherein the number of sheets simultaneously traveling through the entire sheet conveyance path is two. 6. The double-sided image forming apparatus according to claim 2, wherein the second paper to be image-processed immediately after the first paper is taken out from the above-mentioned unprocessed paper storage part (T1), and conveyed via the first paper Path (7), until the conveying direction is reversed by the reversing device, the reversing device (R3) reverses the conveying direction of the first paper, and then sends it to the second paper conveying passage (8). 7. The double-sided image forming apparatus according to claim 6, wherein the first paper sent out to the second paper conveying path (8) after the single-sided image processing is carried out in the first paper conveying path (7) Image processing is carried out on the back of the paper, and the above-mentioned reversing device (R3) reverses the conveying direction of the above-mentioned second paper until it is sent to the above-mentioned image-processed paper storage unit (T2), and then sent to the above-mentioned second paper conveying path (8) . 8. The double-sided image forming apparatus according to claim 7, which is controlled so that the second paper is sent out to the second paper conveying path (8), and then the paper is sent to the first paper conveying path (7). After image processing is performed on the back side and sent to the above-mentioned image-processed paper storage unit (T2), there is only one third paper to be image-processed next in the entire paper conveying path (7, 8). 9. The double-sided image forming apparatus according to claim 4, wherein the length of the largest sheet in the conveying direction among the sheets that can be supplied to the double-sided image forming apparatus is L1, along the second paper conveying path ( 8) When the measured distance from the paper sensor (S3) to the registration roller (R1) is set as L2, the paper sensor (S3) and the registration roller (R1) are set so that L1<L2. 10. The double-sided image forming apparatus according to claim 4, wherein the length of the largest sheet in the conveying direction among the sheets that can be supplied to the double-sided image forming apparatus is L1, along the first paper conveying path ( 7) When the measured distance from the above-mentioned registration roller (R1) to the above-mentioned reversing device (R3) is L3, the above-mentioned registration roller (R1) and the above-mentioned reversing device (R3) are arranged so that L1<L3. 11. The double-sided image forming apparatus according to claim 4, wherein the length of the largest sheet in the transport direction among the sheets that can be supplied to the double-sided image forming apparatus is L1, from the first paper transport path (7 ) in the paper conveying direction, from the intersection of the portion located downstream of the image transfer unit (5) and the second paper conveying path (8) to the registration roller ( When the distance between R1) is L4, the above-mentioned first paper conveyance path (7), second paper conveyance path (8) and above-mentioned registration roller (R1) are arranged so that L1<L4. 12. The double-sided image forming apparatus according to claim 2, the above-mentioned reversing device (R3), In the case of performing image processing on even-numbered sheets of paper, the following actions are performed one or more times: The second paper is taken out from the above-mentioned unprocessed paper storage part (T1), passes through the first paper conveying path (7), until the conveying direction is reversed by the above-mentioned reversing device (R3), and the above-mentioned reversing device (R3) makes The conveying direction of the first paper is reversed, and then sent out to the above-mentioned second paper conveying path (8); Image processing is performed on the back side, until the image-processed paper storage unit (T2) is sent to the above-mentioned image-processed paper storage unit (T2), the conveying direction of the second paper is reversed, and then sent to the above-mentioned second paper conveying path (8), In the case of performing image processing on odd-numbered sheets of paper, after performing the above-mentioned operations one or more times, control is performed so that there is only one third page to be image-processed next in the entire paper conveying path (7, 8). Paper is on its way. 13. The double-sided image forming apparatus according to claim 2, wherein the paper conveying driving parts of the first paper conveying path (7), the second paper conveying path (8) and the reversing device (R3) are respectively driven by different The drive source is driven independently. 14. The double-sided image forming apparatus according to claim 13, wherein each paper conveying drive section of the first paper conveying path (7), the second paper conveying path (8) and the reversing device (R3) is set according to The paper detection device (S1, S2, S3) in the path or turning device (R3) detects whether there is paper or not and works. 15. The double-sided image forming apparatus according to claim 14, wherein the paper detection devices (S1, S2, S3) at least include a first paper detection device (S1) arranged before the upstream side of the registration roller (R1), the paper detection device (S1) When the first paper detection device (S1) detects that another sheet of paper is passing upstream of the registration roller (R1) during the conveyance of the paper in the entire conveyance path (7, 8), the registration roller ( R1) stop. 16. The double-sided image forming apparatus according to claim 15, wherein the paper detection device (S1, S2, S3) further comprises a second paper detection device (S3) arranged in the second paper conveying path (8), The above-mentioned second paper detection device (S3) stops the detected paper at the position when detecting that there is paper passing through the above-mentioned second paper conveying path (8), When the above-mentioned first paper detection device (S1) and the second paper detection device (S3) detect paper at the same time, the rotation of the above-mentioned registration roller (R1) and the rotation of the paper in the above-mentioned second paper conveying path ( The transfer synchronization in 8) is restarted.

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