JP5663047B2 - Image forming apparatus - Google Patents

Description

  Embodiments described in this specification relate to a method of recording a machine-readable code of an image forming apparatus.

  Conventionally, an image forming apparatus that forms an image on a sheet using a colorant (such as toner or ink) that erases at a certain temperature or higher, and an erasing apparatus that erases an image by heating the sheet at a certain temperature or higher. Are known. Reuse of the sheet can be achieved by a system having these apparatuses.

  In addition, an ink jet head that records coded information (for example, a QR code), and a code recording device that erases recorded information by recording white ink on a dot that is recorded using white ink There is.

Japanese Patent Laid-Open No. 7-230517

  When a sheet is reused and a document is managed using a code image, if the position of the code image is determined, the code image is printed and erased at the same position many times. As a result, the printed portion of the code image deteriorates and the code reading accuracy decreases.

  The embodiment has been made to solve the above-described problems, and an object of the present invention is to provide a technique for preventing a decrease in reading accuracy of a code image when a sheet is reused.

  The image forming apparatus according to the embodiment includes an acquisition unit, a control unit, and a printing unit. The acquisition unit acquires machine-readable image data. The control unit determines the print position of the image data acquired by the acquisition unit to be different for each printing. The printing unit prints the image data on the sheet in such a manner that the sheet can be reused at the printing position determined by the control unit.

It is a figure which shows changing the printing position of the code image by the image forming apparatus of embodiment. 1 is a diagram illustrating a system configuration example of an embodiment and a hardware configuration example of an image forming apparatus. FIG. 3 is a diagram illustrating an example of functional blocks of the image forming apparatus according to the first embodiment. 3 is a flowchart illustrating an operation example of the image forming apparatus according to the first embodiment. It is a figure explaining moving the printing position of a code image clockwise. It is a figure which shows the outer side vicinity area of QR Code. It is a figure which shows an example of the functional block of the image forming apparatus of 2nd Embodiment. 10 is a flowchart illustrating an operation example of the image forming apparatus according to the second embodiment. It is a figure explaining extracting a code image from an original bit map image. It is a figure explaining the change of a page description language (PDL). It is a figure which shows an example of the functional block of the image forming apparatus of 3rd Embodiment. 10 is a flowchart illustrating an operation example of an image forming apparatus according to a third embodiment. FIG. 10 is a diagram illustrating a display example when selecting a paper feed sheet.

  When copying (or printing) a document with a QR code, the image forming apparatus of each embodiment shown below prints a code image at a different position (margin) from the original so that the code image is at a different position for each printing. To do. FIG. 1A shows an original that is a source of copying (or printing), but by applying the embodiment, the position of the code image moves on the copy (or printing) destination sheet ( (See FIG. 1B). Similarly, in a system in which a code image is newly generated, newly added to a document, and printed, the code image is printed so that each is at a different position.

Further, the image forming apparatus changes the code printing position only when the reuse paper is fed. It is determined from which cassette the paper is recycled. Further, the image forming apparatus according to the present embodiment determines the print position of the code image by the following method.
・ Change randomly every time.
-Change in order for each sheet (eg, shift one code image clockwise).
・ Change according to the date and time.
・ Cooperation with erasing device (determined from statistics on the location of recently erased paper)

In each embodiment, the following items will be described.
First Embodiment: An example of changing the QR code printing position when copying a QR code original.
Second Embodiment: An example of changing the QR code printing position when printing a document with a QR code.
Third Embodiment: An example in which the QR code printing position is changed when a new QR code image is added during copying (or printing).
Fourth Embodiment: An example in which the user selects whether to use recycled paper or new paper, and the position of the QR code is changed in the case of reused paper.
Fifth embodiment: Other variations of QR code printing positioning.

(Configuration example)
FIG. 2 shows a system configuration example common to the embodiments and a schematic configuration example of the image processing apparatus. The image forming apparatus 100 includes an I / F unit 1 (I / F: Interface) connected to an external device via a LAN (Local Area Network), a USB (Universal Serial Bus), or the like. In the present embodiment, the image forming apparatus 100 is connected to an external PC (Personal Computer) 200 via the I / F unit 1. The image forming apparatus 100 includes an image reading unit 5 that is a scanner that reads a document image, a display unit 2 that notifies the user of information such as the state of the image forming apparatus 100, and an operation unit 3 for the user to perform various operations.

  The image forming apparatus 100 includes a processor 6 that controls each hardware in the image forming apparatus 100 such as a CPU (Central Processing Unit) and an MPU (Micro Processing Unit). An image processing unit 7 that performs processing such as tone correction is included. The image forming apparatus 100 includes a storage unit 8 that stores a control program, data, and the like, and a printing unit 4 (printing unit) that performs printing with erasable toner (coloring material). The image processing unit 7 is implemented by an application specific integrated circuit (ASIC), and the storage unit 8 includes a volatile main memory and a nonvolatile auxiliary storage device. In addition, the printing unit 4 includes a toner cartridge that contains toner that is decolored at a certain temperature or more, a process unit that transfers a toner image onto a sheet, a heat fixing device that fixes the toner image on the sheet, and the like. Including.

(First embodiment)
In the first embodiment, an implementation example when copying a document with a QR code will be described. In this example, an example will be described in which a QR code is arranged at a different position for each sheet when a paper document with a QR code is copied.

  FIG. 3 is a functional block diagram of the image forming apparatus 100 according to the first embodiment, and FIG. 4 is a flowchart illustrating an operation example of the image forming apparatus 100. The functions and operations of the image forming apparatus 100 will be described using these. In the present example, the code detection unit 11, the code rearrangement position determination unit 12, and the code rearrangement unit 13 illustrated in FIG. 3 load the program stored in advance in the storage unit 8 and execute the calculation. This is realized. An implementation in which some or all of these functional blocks are performed by the image processing unit 7 may be used.

  The image reading unit 5 reads the original, and the processor 6 inputs the read first image signal (ACT001). The processor 6 (code detection unit 11) detects and acquires a QR code from the first image signal, and outputs its position information (X, Y coordinate values) (ACT002). A known technique is used for detecting the QR code.

The processor 6 (code rearrangement position determination unit 12) determines the rearrangement position of the QR code. Here, it is assumed that the code images are rearranged while being shifted clockwise by the size of the code image. This will be described with reference to FIG. In the following description, the initial value of the counter value (n, n ′, n ″, n ′ ″) is 1.
(ACT003-1) The coordinates of the upper left vertex of the detected and acquired QR code are set to (x0, y0), and the width and height of the QR code are set to (w, h) (see FIG. 5A). The initial position of the code image (position on the original sheet) is the upper left corner as shown in FIG.
(ACT003-2) The code rearrangement position determination unit 12 acquires the value of the position shift counter n.
(ACT003-3) The code rearrangement position determination unit 12 first shifts the coordinates of the upper left vertex and the lower right vertex of the rearrangement position by one QR code image to the right, and the upper left vertex coordinates (x0 + 1w, Temporarily decide y0). The code rearrangement position determination unit 12 increments the value of the counter n by one.

(ACT003-4) The code rearrangement position determination unit 12 checks whether there is a character or an image at the temporarily determined position, and if not, determines the temporarily determined position as the rearrangement position.
(ACT003-5) The code rearrangement position determination unit 12 further shifts the position to the right when there is a character or the like at the temporarily determined position, and (x0 + 2w, y0), (x0 + 3w, y0),. , And so on (see FIG. 5B). When the white background (margin) is found, the rearrangement position is determined. The value of the counter n is also increased by the number of repeated checks.
(ACT003-6) If the rearrangement position is not found until it protrudes outside the paper, this time, the rearrangement position is determined by shifting downward (see FIG. 5C). That is, when the position immediately before the protrusion (the upper left end of the one-dot chain line in FIG. 5C) is (x1, y0), the code rearrangement position determination unit 12 determines (x1, y0 + 1h), (x1, y0 + 2h), (x1, y0 + 3h), ... and repeat until a white background is found. The value of the counter value (n ′) increases by the number of repetitions.
(ACT003-7) If the arrangement position is not determined even when the sheet is advanced to the lower end of the sheet, the code rearrangement position determination unit 12 repeats the check by shifting one by one in the left direction. The value of the counter (n ″) increases by the number of repetitions (see FIG. 6D).
(ACT003-8) If the arrangement position is not determined even when the paper is advanced to the left end of the paper, the code rearrangement position determination unit 12 repeats the check by shifting one by one upward. The value of the counter (n ′ ″) increases by the number of repetitions (see FIG. 5E).

  The code rearrangement position determination unit 12 outputs the coordinates of the rearrangement position determined in this way to the code rearrangement unit 13.

  The processor 6 (code rearrangement unit 13) draws a QR code image at the rearrangement position (ACT004). That is, the code rearrangement unit 13 sets the upper left vertex coordinates of the code image acquired by the code detection unit 11 to (x0, y0), the width / height (w, h), and sets the upper left vertex coordinates of the rearrangement position. When (x1, y1) is set, the pixel in the rectangular area with the coordinate position of the upper left vertex and the lower right vertex is (x1, y1)-(x1 + w, y1 + h), (x0, y0)-(x0 + Replace with a pixel in the rectangular area of w, y0 + h). This makes it possible to draw a QR image at the rearrangement position.

  The processor 6 (code rearrangement unit 13) removes the code image from the first image and generates a second image (ACT004). For example, as illustrated in FIG. 6, the code rearrangement unit 13 obtains an average pixel value around the detected code image (code image of the first image). The code rearrangement unit 13 overwrites the pixel at the position where the QR code exists with the obtained pixel average value. Thereby, the QR code can be removed from the first image.

  The printing unit 4 receives the second image signal and prints it on the sheet with an erasable color material (ACT005).

  When printing a plurality of sheets in one print job, ACT003 to ACT005 are repeatedly executed for the number of sheets. The counter values (n, n ′, n ′ ′, n ′ ″) are not initialized even when printing on the next sheet, and are maintained at the current values. Thereby, the position of the code image can be varied for each sheet. By adopting such an aspect, it is possible to avoid repeatedly printing a code image at the same position, and to prevent a decrease in reading accuracy of the code image due to deterioration of the recording medium at the time of reuse.

  Further, even when the print job is finished, the counter values (n, n ′, n ′ ′, n ″ ′) may be maintained. In this case, a code image is printed on the first sheet of the next print job at a position corresponding to the counter value.

  In the above example, the position of the code image on the original sheet is described as the upper left corner, but the code image also moves clockwise at the upper right corner, the lower right corner, and the lower left corner. Even if the code image of the original sheet is located in the middle such as the center of the upper end of the sheet, the code image is moved clockwise by specifying the position, and printed at a position different from the code position of the original sheet. It is also possible to do.

  In the above method, the QR code drawn at the rearrangement position is a copy of the code image of the input image. However, depending on the performance of the image reading unit, the image after reading causes image deterioration compared to the original document image. If the code image is printed as it is, the image quality of the code image after printing is deteriorated and the decoding accuracy is reduced. It is also conceivable that the Therefore, the read QR code image is once decoded, information converted into a QR code is extracted, and the information is converted into a QR code image again. The recreated code image can be rearranged on the second image. By adopting such an aspect, not only the printing position is changed, but also a clear code image can be maintained at all times, so that it is possible to prevent the reading accuracy of the code image from being lowered.

(Second Embodiment)
In the first embodiment, an aspect of copying a document with a QR code has been described. In the second embodiment, an example of mounting electronic data of a document with a QR code will be described. In the second embodiment, an example will be described in which QR codes are arranged at different positions for each sheet when electronic data of a document with a QR code is printed.

  FIG. 7 shows functional blocks of the image forming apparatus 100 according to the second embodiment, and FIG. 8 shows an operation example. The aspect of 2nd Embodiment is demonstrated using these. The code detection unit 11A, the code rearrangement position determination unit 12A, the code rearrangement unit 13A, and the raster image formation unit 14 in FIG. 7 are stored in advance in the storage unit 8 by the processor 6 as in the first embodiment. This is realized by loading the program and executing the operation. Further, as in the first embodiment, some or all of these functional blocks may be implemented by the image processing unit 7.

  The I / F unit 1 receives a page description language (PDL (Page Description Language)) generated by the printer driver of the external PC 200 (ACT 101). Here, this PDL is referred to as a first PDL. The processor 6 (code detection unit 11A) interprets the first PDL, and detects and acquires QR codes for all bitmap images included in the PDL (ACT 102). This QR code detection technique can use the same technique as in the first embodiment. When the bitmap image from which the QR code is detected includes other than the QR code, the code detection unit 11A removes the code image from the original bitmap image and newly generates a code image only of the QR code.

FIG. 9A is a bitmap image including other than the QR code, FIG. 9B is a bitmap image after removal, and FIG. 9C is a newly generated QR code image. Here, the same method as that described in the first embodiment can be used as the code image removal method (see the description of ACT004). Here, a method for determining whether or not an image other than a QR code image is included will be described. When the width and height of the bitmap image are W and H, and the width and height of the detected QR code are w and h,
W-w <th1 and H-h <th2
(Where th1 and th2 are relatively small thresholds defined in advance)
If the condition is satisfied, the code detection unit 11A determines that the bitmap image is an image that is not included other than the QR code (an image including only the QR code).

The processor 6 (code rearrangement position determination unit 12A) determines the rearrangement position of the QR code (ACT 103). The rearrangement position is determined clockwise as in the first embodiment. However, the position of the QR code in the first PDL is obtained by the following method.
(1) If the bitmap image does not include an image other than the QR code (in the case of an image of only the QR code), the bitmap image pasting position described in the first PDL is directly used as the QR code on the document. Position.
(2) When the bitmap image includes an image other than the QR code, the pasting position of the bitmap image described in the first PDL is (X, Y), and the QR code detection position in the bitmap image is ( If x, y), the position of the QR code in the first PDL is obtained as (X + x, Y + y).

  In addition, when PDL is analyzed, it is possible to determine at which position each object of a character, a figure, and a bitmap image is arranged, so it is possible to determine whether or not a character or the like is included in a repositioned position of a provisionally determined QR code. .

  The processor 6 (code rearrangement unit 13A) rewrites the first PDL so as to draw a QR code image at the rearrangement position (ACT 104). That is, when the coordinates of the rearrangement position are (x1, y1), the second PDL is generated with the drawing position of the bitmap image representing the QR code as (x1, y1). This will be specifically described with reference to FIG. While the QR code position in the first PDL is (x, y) = (5, 5) (see FIG. 10A), in the generated second PDL, the QR code position is It is changed to (x, y) = (15, 5) with the width size 10 added. As a result, the position of the QR code of the raster image generated in the next step is moved to the right by one QR code compared to the original.

  The processor 6 (raster image forming unit 14) executes RIP processing (RIP: Raster Image Processor) on the second PDL to generate a raster image (ACT 105). This operation uses the same technique as before. The printing unit 4 prints the raster image with an erasable color material (ACT 106).

  In the above example, all processing for the received PDL is executed in the image forming apparatus 100. However, for example, when creating a PDL with the printer driver of the external PC 200, it is possible to execute the same processing, and when creating a GDI command to be output to the printer driver from an editing application operating on the PC. It is also possible to execute similar processing.

  By adopting such a configuration, when printing a manuscript with a code, avoiding repeated printing of the code image at the same position, reducing the reading accuracy of the code image due to deterioration of the sheet when the sheet is reused. Can be prevented.

(Third embodiment)
In the first and second embodiments, the implementation example has been described in which an original sheet or PDL to which a QR code is attached in advance is processed. In the third embodiment, a mode in which a QR code is newly assigned to a document sheet or PDL to which no QR code is attached and copying / printing will be described. In the third embodiment, an example will be described in which information such as a date or a printer is received when a document is copied, the information is encoded, and QR codes are arranged at different positions for each sheet.

  FIG. 11 shows functional blocks of the image forming apparatus 100 according to the third embodiment, and FIG. 12 shows an operation example. The code arrangement position determination unit 12B, the code arrangement unit 13B, and the code image generation unit 16 in FIG. 11 are implemented by the processor 6 and the image processing unit 7 as in the first and second embodiments.

  The image reading unit 5 reads a document without a QR code and inputs the first image signal read by the processor 6 (ACT 201). The processor 6 (code arrangement position determination unit 12B) determines the arrangement position of the QR code (ACT 202). Similar to the first and second embodiments, the arrangement position is determined so as to be different in the clockwise direction for each sheet.

  The processor 6 (code image generation unit 16) acquires the printing time obtained from the image forming apparatus 100 and user information obtained from the operation unit 3 (ACT 203), and generates and acquires a QR code image of these information. (ACT204). A conventional technique for generating the QR code image is employed. The processor 6 (code placement unit 13B) places the QR code image at the position determined by the ACT 202 and generates a second image (ACT 205). The signal of the second image is output to the printing unit 4, and the printing unit 4 forms a second image on the sheet with a color material that can be erased (ACT 206).

  Although the above has described the operation at the time of copying, the same processing can be performed when the PDL is obtained from the external PC 200. In this case, the information to be encoded is not obtained from the operation unit 3, but meta information embedded in, for example, a PDL with a PJL command or the like is set as an encoding target.

  In addition, a code image can be generated using information (for example, a document title, a document number, etc.) in a manuscript sheet as information to be encoded using conventional OCR (Optical Character Reader) technology. Further, it is conceivable that the processor 6 obtains the code image itself via the I / F unit 1 separately from the document image, instead of generating the coded image inside the image forming apparatus 100.

  According to the third embodiment, even in an image forming apparatus that newly copies (or prints) a QR code to an input document, the QR code print position can be changed for each page. By adopting such an aspect, it is possible to avoid repeatedly printing a code image at the same position, and to prevent a decrease in reading accuracy of the code image due to deterioration of the recording medium at the time of reuse.

(Fourth embodiment)
In the fourth embodiment, an implementation example in which the QR code position is changed depending on whether it is a new sheet or a reused sheet will be described.

  In the first to third embodiments, the example in which the QR code print position is changed every time one sheet is printed has been described. However, if the recording medium is unused paper, there is no need to change the printing position. Therefore, new paper and reusable paper are stored in advance in separate paper cassettes, and paper is fed from either cassette from the operation unit 3 of the image forming apparatus 100 during copying, or from the printer driver of the external PC 200 during printing. Let the user choose whether to do. Thus, it is possible to print by changing the position of the QR code using the techniques of the first to third embodiments only when the reuse paper is fed.

  A display example by the display unit 2 at this time is shown in FIG. As shown in FIG. 13A, an implementation may be implemented in which the user selects and selects a reused paper or a new paper in the pull-down menu PM1 for selecting a paper feeding method, and as shown in FIG. 13B, There may be an implementation in which a cassette for storing reused paper or new paper is selected.

  In operation, for example, a determination is made between ACT001 and ACT002 in FIG. 4 as to whether or not a cassette storing reused paper has been selected, that is, whether or not the printing sheet is reused paper. In the case of reusable paper, the process proceeds to ACT003, and in the case of new paper, copying is performed as it is. This determination operation is performed by the processor 6.

  By adopting such a configuration, when unused paper is fed, it is possible to perform printing in the conventional processing time without changing the position of the QR code, and recycled paper is fed. In this case, it is possible to prevent the code image from being repeatedly printed at the same position and to prevent the reading accuracy of the code image from being deteriorated due to the deterioration of the recording medium.

(Fifth embodiment)
In the first to fourth embodiments, the method of shifting the position clockwise by one QR code every time one sheet is printed has been described. Here, other methods are mentioned.

  For example, as the simplest method, only an area where QR codes can be arranged is determined in advance, and QR codes may be arranged randomly within the area. Another possible implementation is to change the location according to the date and time.

  Further, in the first to fourth embodiments, the counter for controlling the deviation amount is increased for each sheet. However, it is considered that the counter is increased by one every time the paper cassette for reused paper is opened and closed. It is done. In this case, if the counter initial value is set to 0, only sheets with a QR code deviation of 0 are initially available. When the reusable paper is fed for the first time, the counter becomes 1 and the deviation amount becomes 1. However, since there is only the paper with the deviation amount 0 in the paper feed cassette, it is not printed at the same location. Similarly, the counter is 2 when the paper is opened and closed for the second time, but most of the papers that are available at this time are papers whose deviation amount is 0 or 1, and therefore are not printed at the same location. Statistical data indicating that most of office documents are discarded within one week after printing, although it is possible that the printing position will circulate and match if the period from printing to reuse is long. For this reason, it is considered that the majority of sheets are reused before the print position goes around. In this case, when the processor 6 receives a signal issued when the open / close state of the cassette (the cassette that supplies sheets) in which the reused paper is stored changes, the print position of the code image is changed to the pre-transition position. The implementation is such that the position is determined to be different from the position. Which position is set may be based on the above clockwise, random, or date / time.

  Furthermore, it is conceivable to determine the QR code printing position based on information obtained from the erasing device. In the case of an erasing apparatus having an image reading means, it is possible to detect the QR code at the time of erasing and record the QR code printing position. The image forming apparatus 100 acquires an index value indicating the frequency at which the QR code is located on the recently erased paper, and determines the rearrangement position while avoiding the most frequent position. Thereby, it is possible to reduce the printing of the QR code at the same position.

  In each of the above-described embodiments, the mode in which the code image is determined to be a position different from the original position or a position different for each printing and printed has been described. In each embodiment, as the original position, when a document sheet is copied, the position of the code image on the document sheet is illustrated, and in the case of printing, the position set and defined in the PDL is illustrated. When a new code image is added, the original position is an assigned position defined by a higher system such as a form system or a document management system.

  In each of the above embodiments, the code image has been described as a QR code, but the aspect is not limited to this. Such a code image may be machine-readable image data such as a barcode other than the QR code. Since the character string can be read and discriminated by using the OCR technique, the character string is also included in the machine-readable image data. Of course, a figure, a design, etc. may be sufficient. The format of such machine-readable image data may be a specified format such as a page description language (PDL) in addition to the raster image.

  In each of the above embodiments, the sheet of the recording medium has been described as a paper medium. However, not only the paper medium but also a sheet made of cloth or plastic may be used.

  In each of the embodiments described above, the code image placement position has been described as being determined to rotate clockwise on the sheet, but may be implemented in a counterclockwise manner. In other words, any mounting around the sheet margin may be used. The sheet margin may be only the top, bottom, left, and right margins of the sheet. However, even if the contents (content image that the user desires to print) are printed in the area where nothing is printed, this area. Can be a sheet margin.

  As an aspect of sheet reuse in each of the above-described embodiments, an example has been shown in which a sheet that has been used in an erasing apparatus is heated and decolored by printing using a color material that is decolored at a certain temperature or higher. The aspect which becomes reusable is not limited to this. In addition to this, there are various modes such as a method of erasing an image by applying a color material of substantially the same color as the paper color, a method of using a dedicated sheet, and a method of removing a color material by laser irradiation. is there.

  You may combine the aspect of each said embodiment, respectively.

  The acquisition unit corresponds to the code detection units 11 and 11A and the code image generation unit 16 of the embodiment. The control unit corresponds to the processor 6 and the storage unit 8 (code rearrangement position determination units 12 and 12A, code arrangement position determination unit 12B). That is, it is realized by the processor 1 performing an operation on a program stored in advance in the storage unit 8.

  As described in detail above, according to the embodiment of the present embodiment, it is possible to avoid printing machine-readable image data over and over again at the same position, thereby reducing the reading accuracy of machine-readable image data. Can be suppressed.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the scope of claims, and is not restricted by the text of the specification. Further, all modifications, various improvements, alternatives and modifications belonging to the equivalent scope of the claims are all within the scope of the present invention.

  1 I / F section, 2 display section, 3 operation section, 4 printing section, 5 image reading section, 6 processor, 7 image processing section, 8 storage section, 11, 11A code detection section, 12, 12A code rearrangement position determination Section, 12B code arrangement position determination section, 13, 13A code rearrangement section, 13B code arrangement section, 16 code image generation section, 14 raster image forming section, 100 image forming apparatus, 200 external PC.

Claims (4)

An acquisition unit for acquiring machine-readable image data;
A control unit that determines a print position of the image data acquired by the acquisition unit to be a position different from the print position before the transition when the state of opening / closing of a cassette that supplies sheets has changed ;
A printing unit that prints the image data on a sheet in a form that enables sheet reuse at a printing position determined by the control unit;
An image forming apparatus. The image forming apparatus according to claim 1.
The control unit further determines the print position of the image data so that each sheet has a position different from the previously printed sheet, and prints the sheet margin around each sheet. An image forming apparatus for determining a position. The image forming apparatus according to claim 1.
The image forming apparatus, wherein the control unit determines a printing position of the image data so as to be in a pre-defined area and a random position. The image forming apparatus according to any one of claims 1 to 3 ,
The control unit is configured to change the printing position of the image data when the printing sheet is a reuse sheet.

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