Image reading device and image forming device

Abstract

To appropriately read a print medium with an image reading device both when the print medium is white and when the print medium has a color other than white.SOLUTION: An image reading device comprises: a reading unit that is arranged at a predetermined place and reads an image formed on a print medium; and a backing unit that is arranged at a place opposite to the reading unit and can change the color of a place to be the background of the print medium when the reading unit performs reading to a plurality of types of colors according to the type of the print medium and / or the color read from the print medium.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image reading device and an image forming device, and more particularly to a technique applied when an image is read using an image sensor or a colorimeter. [Background technology]

[0002] When an image forming device prints on a print medium such as paper or film, the image printed on the print medium is read using a scanner or the like, and the read image data is compared with the print document data to check whether the printing was performed correctly. In such an inspection, for example, the entire printed image is read by a scanner to determine whether the printed image is dirty, whether the amount of ink applied is correct, etc. When inspecting with a scanner, the colors of at least a portion of the printed image are measured by a colorimeter, and the colors of the data read by the scanner are calibrated based on the colors measured by the colorimeter, so that the color inspection of the image read by the scanner can be performed correctly.

[0003] Patent document 1 describes a technique for manually measuring the color on a white background and a black background to obtain the amount of ink deposited on a transparent printing medium by each printer in order to calibrate multiple printers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-73307 A Summary of the Invention [Problem to be solved by the invention]

[0005] In image reading devices that perform reading with a scanner or color measurement with a colorimeter, images printed on white print media are often read, and the location where the scanner or colorimeter is placed is usually a white background. The white background allows the reading and color measurement of images printed on white print media to be performed appropriately.

[0006] However, in the case of an image printed on a transparent film, if the image is read or the color is measured against a white background, there are cases in which the image cannot be read or the color cannot be measured correctly. For example, when printing on a transparent film, a technique called white printing may be used. This white printing involves applying a white coating to the printing area of ​​the film, and then forming images of each color on top of that, resulting in a beautifully colored image. When such blanked-out areas are read against a white background, the white of the printed surface cannot be distinguished from the white of the background, and there is a problem in that the blanked-out areas cannot be read correctly for inspection.

[0007] Here, Patent Document 1 describes a technique for manually switching between color measurement on a white background and color measurement on a black background, and proper inspection can be performed by performing inspections on each background color. However, in the printing process of an actual printing device, whether cut sheets of paper or rolled paper are used as the printing medium, it is necessary to continuously print a large number of sheets to increase productivity. Therefore, if color measurement on a white background and color measurement on a black background are manually switched each time, the inspection takes a lot of time and effort, and it is not possible to inspect the paper printed by the image forming device in real time, which reduces the productivity of the printing work.

[0008] Note that while we have described the issues involved in inspecting images printed on transparent film, a white background may not be appropriate when inspecting images printed on paper other than white.

[0009] An object of the present invention is to provide an image reading device and an image forming device that can appropriately read both white and non-white print media. [Means for solving the problem]

[0010] The image reading device of the present invention includes a reading unit that reads an image formed on a print medium, and a color sensor that is disposed opposite the reading unit and that detects the color of the background of the print medium when the reading unit reads the image, depending on the type of the print medium and / or the color read from the print medium. Turn off It has a replaceable backing and The reading unit is capable of reading a first image formed on a print medium and a second image formed on the first image, and when reading the first image, the reading unit is configured to read the first image from the side on which the second image is formed, and the backing unit switches the color of the background depending on the color of the first image. It is characterized by:

[0011] The image forming apparatus of the present invention further includes a conveying path for conveying a print medium, and a first portion disposed in the conveying path for conveying the print medium. No. 1 image and a second image formed on the first image. an image forming unit that forms an image on the print medium; a reading unit that is disposed at a second location downstream in the transport direction from a first location on the transport path and that reads the image formed on the print medium by the image forming unit; and a reading unit that is disposed at a location facing the reading unit across the transport path and that reads the color of the background of the print medium when read by the reading unit depending on the type of print medium and / or the color read from the print medium. Turn off It has a replaceable backing and The reading unit is capable of reading a first image formed on a print medium and a second image formed on the first image, and when reading the first image, the reading unit is configured to read the first image from the side on which the second image is formed, and the backing unit switches the color of the background depending on the color of the first image. It is characterized by the above. Effect of the Invention

[0012] According to the present invention, simply by selecting the type of paper to be used, the background color when reading an image with the reading unit is changed to a color that allows for appropriate reading, allowing appropriate reading of various colors of paper, transparent films, etc. [Brief description of the drawings]

[0013] [Figure 1] 1 is a configuration diagram showing an example of an image reading device according to an embodiment of the present invention; [Diagram 2]1 is a configuration diagram showing an example of the entire image forming apparatus to which an image reading device according to an embodiment of the present invention is connected; [Diagram 3] 11A to 11C are diagrams illustrating an example of the operation of a backing section according to an embodiment of the present invention. [Figure 4] 5 is a flowchart showing an example of control according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention (hereinafter, referred to as "this embodiment") will be described below with reference to the accompanying drawings.

[0015] [Overall configuration] Fig. 1 shows the configuration of the image reading device of this example, and Fig. 2 shows the overall configuration of the image forming device to which the image reading device of this example is connected. Fig. 1 and Fig. 2 show the configuration on the transport path of the print medium where image formation is performed inside each device.

[0016] First, before describing the image reading device 300 shown in FIG. 1, the overall configuration connected to the image forming device will be described with reference to FIG. In the example shown in Fig. 2, from the right, a paper feeder 100, an image forming apparatus 200, and an image reading apparatus 300 are connected. Note that the entire system in which the paper feeder 100 and the image reading apparatus 300 are connected to the image forming apparatus 200 as shown in Fig. 2 can be regarded as an image forming apparatus, but in the following description, a single apparatus that performs the image forming process is referred to as the image forming apparatus 200. Furthermore, the continuous print medium 11, which is a long print medium that can be loaded into the image forming apparatus 200 in this example, can be a medium made of white paper or film, or a medium made of paper or film of various colors other than white. Furthermore, it can also be a medium made of transparent or translucent film.

[0017] A continuous print medium 11, which is a continuous print medium pulled out from a supply roll (not shown), is supplied to the paper feeder 100, and a plurality of rollers 101-103 are arranged on a transport path for the continuous print medium 11. The paper feeder 100 then performs a process of feeding the continuous print medium 11 to the image forming device 200 at a predetermined speed.

[0018] Image forming apparatus 200 includes, as processing sections constituting the image forming section, toner image forming unit 210, transfer section 220, and fixing section 230. Toner image forming unit 210 forms toner images of each color, such as yellow Y, magenta M, cyan C, black K, and white W, on transfer belt 221 of transfer section 220. The transfer unit 220 transfers the toner images of each color formed on the transfer belt 221 onto the surface of the continuous print medium 11 by means of the transfer rollers 222 .

[0019] The fixing unit 230 includes fixing rollers 231 and 232, and heats the continuous print medium 11 by passing the continuous print medium 11 between the fixing rollers 231 and 232, thereby fixing the transferred print image onto the continuous print medium 11. In the fixing unit 230, the continuous print medium 11 is heated to, for example, about 100°C.

[0020] In addition to the transfer roller 222 and fixing rollers 231, 232, multiple rollers 201-205 are arranged along the transport path of the continuous print medium 11 in the image forming apparatus 200. However, only roller 205, which comes into contact with the back side of the continuous print medium 11 (the side opposite to the surface on which the printed image is formed) is arranged downstream of the fixing unit 230 on the transport path in the transport direction, and the front side of the continuous print medium 11 does not come into contact with any roller. Each of the rollers 201-205 is made of metal, for example. In the following description, downstream and upstream refer to downstream and upstream as viewed from the transport direction of the continuous print medium 11. The continuous print medium 11 on which the print image has been formed by the image forming device 200 is sent to the image reading device 300, which will be described next.

[0021] [Image reader configuration] Next, the configuration of the image reading device 300 will be described with reference to FIG. The image reading device 300 includes a cooling unit 320, a scanner unit 330, a shading unit 350, and a colorimeter unit 360. The continuous print medium 11 passes through these units in order. The scanner unit 330 has a scanner backing portion 340 , and the colorimeter unit 360 has a colorimeter backing portion 370 . Furthermore, a plurality of rollers 301-310 are disposed along the transport path of the continuous print medium 11 within the image reading device 300. Each of the rollers 301-310 is made of, for example, metal.

[0022] The continuous print medium 11 transported inside the image reading device 300 passes near the cooling unit 320. A plurality of cooling fans 321-323 are arranged in the cooling unit 320 to cool the continuous print medium 11. In FIG. 1, the continuous print medium 11 is transported vertically from top to bottom, and the three cooling fans 321-323 arranged vertically cool the transported continuous print medium 11. As the cooling fans 321-323, for example, a type called a sirocco fan, in which plate-shaped blades are attached to a rotating cylinder, is used. Alternatively, the cooling fans 321-323 may be fans equipped with propellers.

[0023] 2, the continuous print medium 11 is heated to about 100° C. by the fixing unit 230 of the image forming device 200, and so the continuous print medium 11 is at a high temperature, for example, about 70° C., when it is supplied to the image reading device 300. For this reason, cooling fans 321-323 supply cooling air toward the continuous print medium 11 to cool it to about room temperature.

[0024] In the cooling unit 320 of the image reading device 300, it is necessary to arrange a plurality of (three) cooling fans 321-323 in the transport direction to provide sufficient cooling performance. In such a case, as shown in Fig. 1, arranging the transport path of the continuous print medium 11 vertically and arranging the cooling fans 321-323 vertically (lengthwise) can contribute to the miniaturization of the image reading device 300. In other words, if the transport path is arranged horizontally and multiple cooling fans are arranged horizontally, the image reading device 300 becomes larger in the horizontal direction, which is not preferable, but the configuration of this example allows the image reading device 300 to be configured to be compact.

[0025] 1 shows three cooling fans 321-323 lined up in the vertical direction, but if the width of the continuous print medium 11 is wide, multiple cooling fans may also be lined up in the horizontal direction (the direction from the front to the back in FIG. 1). For example, a total of nine cooling fans may be installed: three in the vertical direction and three in the horizontal direction.

[0026] In addition, rollers 301, which are arranged in the transport path of the continuous print medium 11 between when the continuous print medium 11 is taken into the image reading device 300 and when it is cooled by the cooling unit 320, are arranged so as to contact the back side of the continuous print medium 11, i.e., the side opposite to the image forming surface. As described in FIG. 2, rollers 205, which are arranged downstream of the fixing unit 230 in the image forming device 200, are also arranged so as to contact the back side of the continuous print medium 11.

[0027] As a result, the image forming surface of the continuous print medium 11 heated by the fixing section 230 of the image forming apparatus 200 does not come into contact with rollers or the like until the continuous print medium 11 is cooled by the cooling unit 320. This prevents the toner image from being distorted due to the image formed on the continuous print medium 11 coming into contact with a roller in a high temperature state, which contributes to improving the image quality of printed images.

[0028] The continuous print medium 11 cooled by the cooling unit 320 is transported upward by two rollers 302, 303, passes through rollers 304, 305, and is transported horizontally in the upper part of the image reading device 300. A scanner unit 330 is disposed in close proximity to the surface of the continuous print medium 11 being transported horizontally.

[0029] The scanner unit 330 is one of the reading units included in the image reading device 300 . In the scanner unit 330 shown in FIG. 1, image light entering the unit from a paper-proximate surface 331 is reflected by a plurality of mirrors 332-336, passes through an optical system 337, and is focused on an image sensor 338. The image recorded on the continuous print medium 11 is then read by the image sensor 338. The image sensor 338 may be configured, for example, as a CCD (Charge Coupled Device) type line sensor. Alternatively, the image sensor 338 may be configured as a CMOS (Complementary Metal Oxide Semiconductor) type sensor. An image sensor other than a line sensor may also be used.

[0030] Data of the image read by the scanner unit 330 is supplied to an image inspection processing unit (not shown), where an inspection process is performed to determine whether the image formed by the image forming apparatus 200 is the same as the original. 1, by forming an image on the image sensor 338 in a state where there is a certain degree of optical path length within the scanner unit 330, it is possible to widen the range in which an image can be correctly formed on the image sensor 338. Therefore, with the configuration shown in FIG. 1, the image formed on the surface of the continuous print medium 11 can be correctly read by the image sensor 338.

[0031] A scanner backing section 340 is disposed on the opposite side of the scanner unit 330 from the paper-proximate surface 331, with the continuous print medium 11 sandwiched between them. The configuration of the scanner backing section 340 will be described later. The scanner backing section 340 is attached to a roller holding member 381. The roller holding member 381 is a member that holds two rollers 305, 306 arranged on the upstream and downstream sides of the scanner unit 330. The roller holding member 381 is connected to two legs 384, 385 that are rotatable around rotation fulcrums 382, ​​383. The legs 384, 385 are rotated along circularly curved guide grooves 386, 387, so that the transport path of the continuous print medium 11 can be separated from the scanner unit 330.

[0032] When the transport path of the continuous print medium 11 moves away from the scanner unit 330 due to the movement of the roller holding member 381, the scanner backing portion 340 attached to the roller holding member 381 also moves in conjunction with the roller holding member 381. In addition, a shading unit 350 is disposed beside roller holding member 381 (on the left side in FIG. 1). This shading unit 350 can be moved in the horizontal direction (left and right direction in FIG. 1) by being driven by a moving section 352. Then, when roller holding member 381 has moved away from scanner unit 330, shading unit 350 can be moved to a position directly below scanner unit 330.

[0033] After passing through the scanner unit 330, the continuous print medium 11 is transported vertically downward by rollers 306, and then transported horizontally again by rollers 308. A colorimeter unit 360 is disposed adjacent to the surface (upper surface) of the continuous printing medium 11 that is transported horizontally by the rollers 308 .

[0034] The colorimeter unit 360 is one of the reading units included in the image reading device 300 . The colorimeter unit 360 has a built-in colorimeter and performs color measurement processing to measure the color of a specific spot on the continuous print medium 11. Based on the color measurement results from the colorimeter, for example, color calibration of an image read by the scanner unit 330 is performed. A colorimeter backing section 370 is disposed on the opposite side of the colorimeter unit 360 from the paper-proximate surface 361, with the continuous print medium 11 sandwiched between them. The configuration of the colorimeter backing section 370 will be described later.

[0035] The continuous print medium 11 that has passed through the colorimeter unit 360 is transported outside the image reading device 300 via rollers 309 and 310, and is wound up onto a winding roll (not shown).

[0036] [Configuration of the scanner backing and colorimeter backing] FIG. 3 shows the configuration of a scanner backing section 340 arranged opposite to the scanner unit 330 and a colorimeter backing section 370 arranged opposite to the colorimeter unit 360. 3 is a side view of the scanner backing unit 340 and the colorimeter backing unit 370 when the continuous print medium 11 is transported from right to left. In FIG. 3, the upper side of the continuous print medium 11 is the surface on which an image is formed by the image forming device 200.

[0037] The scanner backing section 340 includes a backing member 341. The backing member 341 faces the paper-proximate surface 331 of the scanner unit 330 with the continuous print medium 11 sandwiched therebetween. The backing member 341 has a black portion 341B that is entirely black adjacent to a white portion 341W that is entirely white. The backing member 341 can be switched between a state in which the black portion 341B is located directly below the paper-proximate surface 331 and a state in which the white portion 341W is located, by moving the backing member 341 in a horizontal direction M1 by a drive mechanism (not shown).

[0038] The colorimeter backing section 370 includes a backing member 371. The backing member 371 faces the paper-proximate surface 361 of the colorimeter unit 360 with the continuous print medium 11 sandwiched therebetween. The backing member 371 has a black portion 371B that is entirely black adjacent to a white portion 371W that is entirely white, similar to the backing member 341. The backing member 371 can be switched between a state in which the black portion 371B is located directly below the paper-proximate surface 361 and a state in which the white portion 371W is located, by moving the backing member 371 in the horizontal direction M2 by a drive mechanism (not shown).

[0039] Which color portion of the backing members 341, 371 is placed as the background color directly below each paper-proximate surface 331, 361 is set according to the color and type of the continuous print medium 11 loaded in the image forming apparatus 200 and the color for image formation by the image forming apparatus 200. The setting of the backing members 341, 371 is executed, for example, in response to an instruction from a control unit (not shown) of the image forming apparatus 200.

[0040] [Example of setting the color of the scanner backing and colorimeter backing] FIG. 4 is a flowchart showing an example of a process for setting the background colors of the scanner backing section 340 and the colorimeter backing section 370.

[0041] First, the control unit of the image forming device 200 determines whether the continuous print medium 11 loaded in the image forming device 200 or the image reading device 300 is a white print medium or a non-white print medium (step S11). The color of the loaded continuous print medium 11 is set in advance by the printing operator on the operation panel of the image forming device. Note that non-white print media here includes transparent or translucent films in addition to papers and films of various colors.

[0042] When it is determined in step S11 that the color is white ("white" in step S11), the control unit of the image forming device 200 instructs the backing units 340, 370 to switch in unison so that the white units 341W, 371W are directly below the paper-proximate surfaces 331, 361 (step S12). Furthermore, when it is determined in step S11 that the color is not white ("other than white" in step S11), the control unit of image forming apparatus 200 determines whether the toner colors (or ink colors) used when forming an image in toner image forming unit 210 are only yellow Y, magenta M, cyan C, and black K (step S13).

[0043] If the toner colors to be used to form an image in step S13 are only yellow Y, magenta M, cyan C, and black K ("YMCK only" in step S13), the control unit of image forming device 200 proceeds to step S12 and issues an instruction to switch white portions 341W, 371W so that they are directly below paper-proximate surfaces 331, 361.

[0044] Furthermore, if the toner colors used to form an image in step S13 are other than yellow Y, magenta M, cyan C, and black K ("other than YMCK" in step S13), the control unit of image forming apparatus 200 issues an instruction to switch backing units 340, 370 in conjunction with each other so that black units 341B, 371B are directly below paper-proximate surfaces 331, 361 (step S14). Note that, as a color other than yellow Y, magenta M, cyan C, and black K, an image may be formed in white, for example. When an image is formed in white, a process called white printing is included, which is formed on a transparent film as a base when forming an image of another color.

[0045] Then, with the background colors of the scanner backing section 340 and the colorimeter backing section 370 set in step S12 or S14, the image reading device 300 performs reading of the printed continuous printing medium 11 using the scanner unit 330 and the colorimeter unit 360 (step S15).

[0046] As described above, in the image reading device 300 of this example, when the print medium on which the image is formed by the image forming device 200 is white, or when the print medium is other than white and only toners (inks) of yellow Y, magenta M, cyan C, and black K are used, the backing members 341, 371 become white. Therefore, images formed in various colors on the white or non-white colored or transparent continuous print medium 11 can be properly read by the scanner unit 330 for print image inspection and by the colorimeter unit 360 for color inspection on a white background color.

[0047] Furthermore, when the print medium on which the image is formed by the image forming apparatus 200 is a print medium other than white and a toner (ink) other than yellow Y, magenta M, cyan C, or black K is used, each backing member 341, 371 becomes black. For example, when an image is formed on the continuous print medium 11 formed of a transparent film with white toner or ink, each backing member 341, 371 becomes black. Therefore, reading of an image formed in a color such as white for print image inspection by the scanner unit 330 and reading of the image for color inspection by the colorimeter unit 360 can be properly performed on the background color of black, which is a color other than white.

[0048] As a result, in the image reading device 300 of this example, even when reading an image of a portion where a white image has been formed by white printing on a transparent film, the back surfaces of the scanner unit 330 and the colorimeter unit 360 become black, making it possible to accurately read the state of the white image formation. Also, when reading an image formed with toner or ink other than white, the back surface becomes white, making it possible to accurately read the image in the same way as in the past.

[0049] [Variations] In the above-described embodiment, an image is formed on a long continuous print medium, and the print medium on which the image is formed is read. However, the present invention may also be applied to an image forming device or image reading device that forms an image on a print medium such as paper or film cut to a specified size one sheet at a time, and then reads the print medium on which the image is formed.

[0050] 2, the embodiment described above is applied to image reading device 300, which is connected to image forming device 200 and reads an image after the image has been formed by image forming device 200. In contrast, a print medium on which an image has already been formed by a separate image forming device may be attached to a standalone image reading device and the image may be read. In addition, the configuration of image forming apparatus 200 in which a toner image is fixed to a print medium by fixing unit 230 as shown in FIG. 2 is also one example, and the present invention may be applied to image forming apparatuses of other types, such as an inkjet type that uses ink.

[0051] In the image reading device described in the above embodiment, the backing members 341, 371 of both the scanner backing unit 340 and the colorimeter backing unit 370 are switched to the same color in conjunction with each other. However, only one of the scanner backing unit 340 and the colorimeter backing unit 370 may be configured to switch to multiple colors.

[0052] Also, the backing members 341, 371 are switched between white and black in color. This color combination may be other colors depending on the color of the print medium read by the image reading device 300 and the color of the image formed on the print medium. For example, the backing members 341, 371 may be switched between white and gray.

[0053] 4, the colors of the scanner backing unit 340 and the colorimeter backing unit 370 are switched under two conditions: the color of the print medium and the color of the image formed. In contrast, the color of the scanner backing unit 340 or the colorimeter backing unit 370 may be switched only under either the color of the print medium or the color of the image formed. For example, the color of the scanner backing unit 340 or the colorimeter backing unit 370 may be switched between a case where the colors of the image formed are only yellow Y, magenta M, cyan C, and black K, and a case where the colors of the image formed are other than these colors, such as white.

[0054] 1 is also an example, and images may be read by sensors of other configurations. For example, images may be read by a scanner having a line sensor disposed on the paper-proximate surface 331, without using an optical system such as a lens. [Explanation of symbols]

[0055] 11...continuous printing medium, 100...paper feeder, 200...image forming device, 201-205...rollers (guide members), 210...toner image forming unit, 220...transfer section, 221...transfer belt, 222...transfer roller, 230...fixing section, 231, 232...fixing roller, 300...image reading device, 301-310...rollers (guide members), 320...cooling unit, 321-323...cooling fan, 330...scanner unit, 331...paper adjacent surface, 332-336...mirror, 337... Optical system, 338... image sensor, 340... scanner backing section, 341... backing member, 341B... black section, 341W... white section, 350... shading unit, 352... moving section, 360... colorimeter unit, 361... paper adjacent surface, 370... colorimeter backing section, 371... backing member, 371B... black section, 371W... white section, 380... conveying path variable section, 381... roller holding member, 382, ​​383... pivot point, 384, 385... legs, 386, 386... guide groove

Claims

1. A reading unit that reads an image formed on a print medium; a backing unit that is disposed opposite the reading unit and that is capable of changing the color of the background of the print medium when the reading unit reads the print medium depending on the type of the print medium and / or the color read from the print medium; the reading unit is configured to be capable of reading a first image formed on the print medium and a second image formed on the first image, and when reading the first image, to read the first image from the side on which the second image is formed; the backing portion switches a color of the background in accordance with a color of the first image; It is characterized by Image reading device.

2. The reading unit is at least one of an image sensor that reads the image formed on the print medium and a colorimeter that measures the color of the image formed on the print medium.

2. The image reading device according to claim 1.

3. The reading unit includes both the image sensor and the colorimeter, and the backing unit is provided at each of the locations where the image sensor and the colorimeter are arranged.

3. The image reading device according to claim 2.

4. The backing unit installed opposite the image sensor and the backing unit installed opposite the colorimeter are switched to the same color in conjunction with each other.

4. The image reading device according to claim 3.

5. The image sensor is a line image sensor.

5. The image reading device according to claim 2.

6. The first image is an image formed in white, the backing portion changes the color of the background portion to a color other than white depending on the color of the image formed in white; 2. The image reading device according to claim 1.

7. The print medium is a medium of a color other than white, the backing portion switches the color of the background portion to a color other than white depending on whether the print medium is a color other than white and the color of the image formed in the white color.

7. The image reading device according to claim 6.

8. The print medium is a transparent medium, the backing portion switches the color of the background portion to a color other than white depending on whether the print medium is a transparent medium and the color of the image formed in white.

7. The image reading device according to claim 6.

9. The backing part can be switched between white and black.

9. The image reading device according to claim 1.

10. a transport path for transporting a print medium; an image forming unit that is disposed at a first location on the transport path and that forms a first image on the print medium and a second image formed on the first image; a reading unit that is disposed at a second location on the conveying path downstream in a conveying direction from the first location, and that reads an image formed on the print medium by the image forming unit; a backing unit that is disposed opposite the reading unit across the transport path and that is capable of switching the color of the background of the print medium when the reading unit reads the print medium depending on the type of the print medium and / or the color read from the print medium; the reading unit is configured to be capable of reading a first image formed on the print medium and a second image formed on the first image, and when reading the first image, to read the first image from the side on which the second image is formed; The backing portion is characterized in that the color of the background is changed depending on the color of the first image. Image forming device.

Images