IL111514A - Apparatus and method for duplex printing - Google Patents

Description

APPARATUS AND METHOD FOR DUPLEX PRINTING TP S-YT nOQin? nwi un A. Tally Eitan Law Offices C:P-IO-610-IL P-600\610\610ILFIN.BA FIELD OF THE INVENTION The present invention relates to duplex printing generally.

BACKGROUND OF THE INVENTION Systems and methods for printing on both sides of a substrate, such as paper, are known in the art. Printing on both sides of a substrate, also known as duplex printing, is a desirable feature of any printer since duplex printing reduces the amount of paper used.

Prior art systems for duplex printing can be classified into two categories. In one category, the printing mechanism is doubled so that the paper is printed either on both sides simultaneously or in a pipeline manner. A drawback of printers of this category is that they are expensive and therefore, they are usually only used for high speed printing.

In the second category, both sides are printed by the same printing head. Therefore, there is a need to flip the paper after it had been printed on one side in order to print on its other side. The paper can be flipped manually by an operator or by any of the flipping mechanisms known in the art.

As is well known in the art, the image to be printed is represented as a digital image stored in the computer which controls the printer. The image may be a graphic image, a text or any combination thereof.

Since duplex printers with a single printing head print on one side of a batch of substrates first, and then on the other side thereof, the images to be printed are stored in the computer in an order, typically in sequence. Therefore, the substrates must be fed into the printer in the same order in the second pass, i.e when the second side of the substrates is printed, as in the first pass, i.e. when the first side of the substrates is printed.

A drawback of duplex printers with a single printing head is that if the substrates to be printed are not fed in the same order in the first pass and in the second pass, the substrate will not include the correct image on its second side. Moreover, if the substrates are fed in a different orientation in the second pass than in the first pass, the image on the second side thereof will be in an undesired orientation.

SUMMARY OF THE INVENTION The present invention seeks to provide a duplex printing system and a printing method which enables printing of the second side of a substrate in any desired order.

The present inventor has realized that by printing a machine readable code in addition to the desired image on one side of each substrate, the printing system may assign the correct image to be printed on the other side thereof, irrespective and independent of the order in which the substrates are fed into the printing system.

Further, the present inventor has realized that by printing two machine readable codes in addition to the desired image on the first side of each substrate, the printing system may assign the image to be printed on the second side of the substrate in a correct orientation.

There is thus provided, in accordance with a preferred embodiment of the present invention, a printing system which comprises a printing system which includes a printing unit, a reader and a processing unit. The printing unit receives a digital representation of a first image and at least one machine readable code and prints the first image on a first side of a printing substrate and the at least one machine readable code. The reader reads the printed machine readable code, preferably a bar-code, and provides it to the processing unit. The processing unit provides the digital representation of a second image associated with the machine readable code to the at least one printing unit for printing a second image on a second side of the printing substrate, preferably in an orientation which is generally similar to the orientation of the printed first image.

Further, according to a preferred embodiment of the present invention the printing system may include a storage unit for storing the digital representation of the first image, the digital representation of the second image and the digital representation of the at least one machine readable code.

Still further, the reader and the printing unit are on opposite sides of the printing substrate which may be paper.

Additionally, according to a preferred embodiment of the present invention the printing head may be a moving printing head. Further, the printing system may include at least two printing units, wherein at least one of the at least two printing units prints the first image and second image and at least a different one of the at least two printing units prints the machine readable code. The at least one printing unit for printing the image and the at least one printing unit for printing the machine readable code may be on opposite sides of the printing substrate or on the same side thereof.

There is also provided, in accordance with a preferred embodiment of the present invention a printing method which includesthe following steps: A. receiving a digital representation of a first image and at least one machine readable code; B. printing the first image and the at least one machine readable code on a first side of a printing substrate; C. reading the printed machine readable code; and D. providing the digital representation of a second image associated with the machine readable code for printing a second image on a second side of the printing substrate.

Additionally, according to the present invention, the printing method may also include the step of storing the digital representation of the first image, the digital representation of the second image and the digital representation of the at least one machine readable code. It may also include the step of providing the digital representation of the second image in an orientation which is generally similar to the orientation of the printed first image.

There is also provided, in accordance with a preferred embodiment of the present invention a method for duplex printing which includes the following steps: A. providing to a printing system at least two printing substrates; printing an image and a machine readable code on one side of each of the at least tooo printing substrates, where each one of the at least two substrates receives a different machine readable code; B. collecting the at least two substrates; C. providing the at least two substrates to the printing system in any order; and D. for each of the at least two substrates: D1. reading the machine readable code; and D2. printing a second image associated with the machine readable code on the second side thereof.

Additionally, according to the present invention the printing method may include for each of the at least two substrates the step of storing a digital representation of the first image, a digital representation of the second image and a digital representation of the at least one machine readable code.

Finally, according to the present invention the printing method may include the step of providing the digital representation of each second image in an orientation which is generally similar to the orientation of a corresponding printed first image.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the appended drawings in which: Fig. 1 is a schematic isometric illustration of a printing system, constructed and operative according to a preferred embodiment of the present invention, and in a first printing position; and Fig. 2 is a schematic isometric illustration of the printing system of Fig. 1 in a second printing position.

DETAILED DESCRIPTION OF THE PRESENT INVENTION Reference is now made to Figs. 1 and 2 which are schematic illustrations of a printing system according to a preferred embodiment of the present invention. The printing system, generally referenced 100, may be any duplex printing system, such as an ink-jet printing system. An example of an ink-jet printing system is the commercially available Scitex Outboard printer which is a large format continuous ink-jet printer used for billboard printing.

The printing system 100 preferably comprises any feed-in mechanism, such as rollers 102 operated by a motor 104, for feeding substrates to be printed into a printing position, a printing head 106 for printing an image and a machine readable code, such as a bar-code, on one side of the printed substrate, a code reader, such as a bar-code reader 108, for reading the printed machine readable code, a Central Processing Unit (CPU) 110 for controlling the operation of the printing system 100, a memory (not shown) for storing the digital representations of the images to be printed and a list of numeric codes which represent machine readable codes, such as barcodes.

It will be appreciated that the printing system 100 may include more than one printing head. It may, for example, include the printing head 106 for printing the image and an additional printing head for printing the machine readable code.

The system 100 also preferably comprises a feed-out mechanism, such as rollers 112 operated by a motor 114, and a collector 116 for collecting the printed substrates after printing.

For exemplary purposes only, and as a non-limiting embodiment, the printing system 100 will be described with respect to sheets of paper such as the three different sheets indicated by reference numerals 120, 122 and 124, respectively. It will be appreciated that the printing system 100 may be fed with any suitable substrate to be printed, such as paper or plastic, in any suitable form, such as a continuous roll of paper, and in any format.

The printing system 100 prints on the second side of each one of the sheets 120, 122 and 124, the correct image irrespective of the order by which they are fed into the printing system 100. As illustrated in the drawings, in Fig. 1 the sheet 122 is shown in the collecting system after one side thereof has been printed, the sheet 120 is shown in a printing position and the printing system 100. In Fig. 2, the sheet after its second side has been printed, the sheet 122 is shown in a printing position of its second side, and the sheet 120 is shown before it is fed into the printing system 100 for printing the second side thereof.

According to one preferred embodiment of the present invention, the images are stored in the memory such that each pair of images which are to be printed on the same sheet are associated with a numeric code of a printed bar-code. In the first pass, the printing head 106 prints a different image and a different bar-code on each one of the sheets 120, 122 and 124. In the second pass, the bar-code reader 108 reads the bar-code printed on the first side of each sheet that is being fed into the printing system 100, and in accordance therewith the correct image for printing is retrieved from the memory by the CPU 1 0.

According to another preferred embodiment, two bar-codes of two different numeric codes are assigned to each pair of images. For example, bar-codes 128 and 130 are printed on two opposite ends of the sheet 122 (Fig. 1). In the second pass, the bar-code reader 108 reads only the first bar-code of the two barcodes according to the direction by which the sheet is fed to the printing unit. Since the position of the two bar codes in respect to the printed image on the first side is known, the CPU 110 can provide the correct image to be printed on the second side in the correct orientation. For example, if the sheet 122 is fed in the second pass with the edge of the bar-code 130 first, the CPU will rotate the image such that the images on both sides of the sheet 122 will be printed with the same orientation.

Reference is now made specifically to Fig. 1 which schematically illustrates the printing system 100 in a first pass. Preferably, each one of the sheets 120, 122 and 124 is fed into the printing system 100 using the feeding mechanism 102 as shown for the sheet 120. Then, as shown for the sheet 120, the printing head 106 prints an image 134 and the bar-code 132 assigned thereto. Then, the printed sheet is fed-out to the collector 116 by the feed-out mechanism 112. The sheet 122 is shown with the image 126 and the two bar-codes, 128 and 130, in the collector 116.

Reference is now made specifically to Fig. 2 which schematically illustrates the printing system 100 in a second pass. As indicated hereinabove, the sheets 120, 122 and 124 may be printed in the second pass in a different order than that in which they were printed in the first pass.

In the second pass, the bar-code reader 108 reads the bar-code printed on the first side of a sheet after it is fed into the printing system 100 and before it is printed. Preferably, the printing head 106 and the bar-code reader 108 are located on opposite sides of the sheet since the bar-code is on the opposite side of the side to be printed in the second pass.

The sheet 120 is shown before it is fed into the printing system and 111514/2 therefore it carries only the image 134 and the bar-codes 132 and 136 printed thereon in the first pass.

For the sheet 122, which is in a printing position of its second side, the bar-codes 128 (shown in dotted lines in Fig. 2) is read by the bar-code reader 108. In accordance therewith the CPU 110 retrieves the image to be printed and provides it to the printing head 106 which prints an image 138. It will be appreciated that since the bar-code 128 has been read, the printing system will ignore the bar-code 130 (not shown in Fig. 2).

The sheet 124 is shown in the collector 116 after an image 140 was printed thereon and after the bar-code 142 was read by the bar-code reader 108 when the sheet 124 was in a printing position.

It will be appreciated that once a bar-code is read, the numeric code associated therewith is provided to the CPU 110, which, in turn, retrieves from the memory the correct image. Moreover, if the image is not in a correct orientation, the CPU 110 rotates the image and provides it to the printing head 106 in the correct orientation.

A preferred method for printing with the printing system 100 preferably includes the following steps: A. assigning a numeric code of a specific bar-code (preferably two numeric codes of two bar-codes) to each of two images which are to be printed or\ two opposite sides of the same sheet; B. feeding to the printing system 100 a sheet to be printed; C. printing a first image to be printed on one side of the fed sheet and in addition thereto printing the bar-codes assigned to the printed image, preferably along the sheet margins; D. repeating steps B and C for a desired number of sheets; E. collecting the printed sheets and flipping them in any order; F. feeding the printing system with a sheet printed from one side in any orientation; G. reading the first bar-code which the bar-code reader recognizes; if no code is detected then the sheet to be printed is rolled out from the printing system; H. retrieving the image associated with the numeric code of the read barcode in a correct orientation and providing it to the printing head; I. printing the retrieved image; and H. repeating steps F - 1 for a desired number of sheets, thereby printing on both sides of a desired number of sheets.

It will be appreciated that the preferred embodiments described hereinabove are described by way of example only and that numerous modifications thereto, all of which fall within the scope of the present invention, exist. For example, the machine readable code may be any suitable code, such as an Infra-Red (IR) sensitive bar-code. Since the IR bar-code is not visible to the human eye the printed sheet appears without any additional markings thereon. Another example is to employ any suitable reader, such as an Optical Character Recognition (OCR) reader and to employ an appropriate printed code.

Another example is that the printing system 100 enables pri An additional example is that the machine readable code may be printed with a different printing unit than the printing unit for printing the images. For example, if the machine readable code is oIR sensitive code its printing unit may be a different printing unit than the one which prints the image. The two printing units may be positioned on the same side of the printed substrate or on opposite sides thereof. Accordingly, the reader will be on the opposite side of the code printing unit.

It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention is defined only by the claims that follow:

Claims (19)

1. A printing system comprising: a printing unit; a reader; and a processing unit; Wherein said printing unit receives a digital representation of a first image and at least one machine readable code and prints said first image on a first side of a printing substrate and said at least one machine readable code, Wherein said reader reads said printed machine readable code and provides it to said processing unit, and Wherein said processing unit provides the digital representation of a second image associated with said machine readable code to said at least one printing unit for printing a second image on a second side of said printing substrate.

2. A printing system according to claim 1 and also comprising a storage unit for storing said digital representation of said first image, said digital representation of said second image and said digital representation of said at least one machine readable code.

3. A printing system according to any of the previous claims wherein said processing unit also comprises means for providing the digital representation of said second image in an orientation which is generally similar to the orientation of said printed first image. 111514/2

4. A printing system according to any of the previous claims wherein said reader and said printing unit are on opposite sides of said printing substrate.

5. A printing system according to any of the previous claims wherein said reader is a bar-code reader and said machine readable code is a bar-code.

6. A printing system according to any of the previous claims wherein said printed substrate is paper.

7. A printing system according to any of the previous claims wherein said printing head is a moving printing head.

8. A printing system according to any of the previous claims which comprises at least two printing units, wherein at least one of said at least two printing 5 units prints said first image and second image and at least a different one of said at least two printing units prints said machine readable code.

9. A printing system according to claim 8 wherein said at least one printing unit for printing said first image and second image and said at least one printing unit o which prints said machine readable code are on opposite side of the printing substrate.

10. A printing system according to claim 8 wherein said at least one printing unit for printing said first image and second image and scud at least one printing unit which prints said machine readable code are on the same side of the printing substrate. 111514/2

11. A printing method comprising the steps of: receiving a digital representation of a first image and at least one machine readable code; printing said first image and said at least one machine readable code on a first side of a printing substrate; reading said printed machine readable code; and providing the digital representation of a second image associated with said machine readable code for printing a second image on a second side of said printing substrate.

12. A printing method according to claim 11 and also comprising the step of storing said digital representation of said first image, said digital representation of said second image and said digital representation of said at least one machine readable code.

13. A printing method according to any of claims - 12 and also comprising the step of providing the digital representation of said second image in an orientation which is generally similar to the orientation of said printed first image.

14. A method for duplex printing comprising the steps of: providing to a printing system at least two printing substrates; printing an image and a machine readable code on one side of each of said at least "tioo printing substrates, where each one of said at least two substrates receives a different machine readable code; collecting said at least two substrates; providing said at least two substrates to said printing system in any order; and for each of said at least two substrates: reading said machine readable code printed thereon; and printing a second image associated with said machine readable code on the second side of said substrate.

15. A printing method according to claim 14 and also comprising, for each of said at least two substrates, the step of storing a digital representation of said first image, a digital representation of said second image and a digital representation of said at least one machine readable code.

16. A printing method according to any of claims 14 - 15 and also comprising the step of providing the digital representation of each second image in an orientation which is generally similar to the orientation of a corresponding printed first image.

17. A printing system substantially as claimed in any of claims 1 - 10.

18. A printing system substantially as illustrated in any of the drawings hereinabove.

19. A printing method substantially as claimed in any of claims 11 - 16. A method substantially as illustrated in any of the drawings hereinabove. For Law Offices of A. Tally Eitan C: P-IO-610-IL