Inkjet printer

Abstract

To accurately measure length of the printing region of a transparent recording medium.SOLUTION: A printer 10 has: a platen 16 placed with a transparent recording medium 5; a pair of restriction members 90 restricting floating up of both end parts in a main scanning direction Y of the recording medium 5 placed on the platen 16; an optical sensor 31 provided movably in the main scanning direction Y above the recording medium 5 placed on the platen 16 and the restriction members 90 and irradiating light and receiving reflectance; and a control device 80 connected to the optical sensor 31. Colors of the platen 16 and the restriction members 90 are different from each other. The control part 80 measures a length LX in the main scanning direction Y of a printing region of the recording medium 5, on the basis of a first light receiving amount of light reflected in the pair of the restriction members 90 when the optical sensor 31 moves in the main scanning direction Y while irradiating the light, and a second light receiving amount of light passing through the recording medium 5 and reflected in the platen 16.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an inkjet printer. [Background technology]

[0002] Inkjet printers that print on a recording medium using an inkjet method have been known for some time. This type of inkjet printer includes, for example, a platen on which a recording medium, which is transported in a sub-scanning direction, is placed, and an ink head that is movable in a main scanning direction that intersects the sub-scanning direction and ejects ink onto the recording medium placed on the platen. Inkjet printers typically need to measure the position of the recording medium before starting printing. For example, Patent Document 1 discloses an inkjet printer that includes an optical sensor that is movable in the main scanning direction and measures the edge of the recording medium. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-101981 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-68420 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, as shown in Patent Document 2, inkjet printers sometimes use suppression members that press down on both ends of the recording medium in the main scanning direction to suppress floating of the recording medium. In this type of inkjet printer, for example, the length of the printing area of ​​the recording medium may be measured based on the amount of light reflected by the suppression member and the amount of light reflected by the recording medium when an optical sensor is moved in the main scanning direction with the recording medium pressed down by the suppression member.

[0005] However, when using a transparent recording medium, the length of the printing area of ​​the recording medium is measured based on the amount of light received that passes through the recording medium and is reflected at the platen, rather than the light reflected at the recording medium, and the amount of light received that is reflected at the suppression member, so the difference between these amounts of light received becomes small, and there is a risk that the length of the printing area of ​​the recording medium cannot be measured.

[0006] SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an inkjet printer that can accurately measure the length of a printing area on a transparent recording medium. [Means for solving the problem]

[0007] The inkjet printer according to the present invention includes a platen on which a transparent recording medium is placed, an ink head that ejects ink onto the recording medium placed on the platen and is movable in a main scanning direction, a pair of suppression members that are movable in the main scanning direction relative to the platen and that suppress lifting of both ends of the recording medium placed on the platen in the main scanning direction, an optical sensor that is movable in the main scanning direction over the recording medium placed on the platen and the suppression members and that emits light and receives reflected light, and a control device connected to the optical sensor. The color of the platen and the color of the suppression members are different. The control device measures the length of the print area of ​​the recording medium in the main scanning direction based on a first amount of light reflected by the pair of suppression members and a second amount of light received by the platen after passing through the recording medium when the optical sensor moves in the main scanning direction while emitting light.

[0008] In the inkjet printer according to the present invention, the color of the platen is different from the color of the suppression member. In other words, the reflectivity of the platen is different from the reflectivity of the suppression member. Therefore, a clear difference occurs between the first amount of light reflected by the suppression member and the second amount of light transmitted through the recording medium and reflected by the platen. This allows the control device to, for example, determine the transition point between the first amount of light received and the second amount of light received, and measure the length of the print area of ​​the recording medium in the main scanning direction. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an inkjet printer that can accurately measure the length of a print area on a transparent recording medium. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a front view of a printer according to an embodiment. [Figure 2] FIG. 1 is a cross-sectional view of a printer according to an embodiment. [Figure 3] FIG. 2 is a front view of the ink head unit. [Figure 4] FIG. 2 is an enlarged plan view of a portion of the structure around the platen according to the embodiment. [Figure 5] FIG. 2 is a block diagram of a control system of a printer according to an embodiment. [Figure 6] 10A and 10B are diagrams illustrating the relationship between the positional relationship between the platen and the suppressing member and the voltage corresponding to the amount of light received by the platen and the suppressing member. DETAILED DESCRIPTION OF THE INVENTION

[0011] An inkjet printer (hereinafter simply referred to as "printer") according to an embodiment of the present invention will be described below with reference to the drawings. It should be noted that the embodiment described here is not intended to limit the present invention in any way. Furthermore, members and parts that perform the same function are given the same reference numerals, and duplicate descriptions will be omitted or simplified as appropriate.

[0012] FIG. 1 is a front view of a printer 10 according to this embodiment. The printer 10 prints on a recording medium 5. The recording medium 5 is formed into a long length and wound into a roll before use. The recording medium 5 may also be in sheet form, having been wound into a roll and cut to a predetermined length. The recording medium 5 according to this embodiment is, for example, a transparent resin sheet. A "transparent" recording medium 5 includes a completely colorless and transparent recording medium and a recording medium that is slightly colored. The printer 10 according to this embodiment is not limited to a transparent recording medium 5, and can also print on commonly used colored recording media (for example, white).

[0013] In the following description, left, right, top, and bottom refer to the left, right, top, and bottom directions, respectively, as seen from the perspective of an operator standing in front of the printer 10. Furthermore, when the operator is facing the printer 10, the direction from the rear of the printer 10 toward the operator is referred to as the front, and the direction from the operator toward the rear of the printer 10 is referred to as the rear. The symbols F, Rr, L, R, U, and D in the drawings represent the front, rear, left, right, top, and bottom, respectively. The carriage 28, which will be described later, is movable left and right. The rear side of the printer 10 is referred to as the upstream side, and the front side of the printer 10 is referred to as the downstream side. The recording medium 5 is transported from the upstream side to the downstream side. In this embodiment, the movement direction of the carriage 28 is referred to as the main scanning direction Y, and the transport direction of the recording medium 5 is referred to as the sub-scanning direction X. Here, the main scanning direction Y corresponds to the left-right direction, and the sub-scanning direction X corresponds to the front-to-back direction. The main scanning direction Y and the sub-scanning direction X are perpendicular to each other. However, the main scanning direction Y and the sub-scanning direction X are not particularly limited, and can be set appropriately depending on the configuration of the printer 10, etc.

[0014] As shown in FIG. 1, the printer 10 includes a printer body 10a, legs 11, an operation panel 12, a platen 16 on which a transparent recording medium 5 is placed, an ink head unit 20, a carriage movement mechanism 40, a medium movement mechanism 55, and a control device 80. The printer body 10a has a casing extending in the main scanning direction Y. The legs 11 support the printer body 10a and are provided on the underside of the printer body 10a. The operation panel 12 is provided, for example, on the front right side of the printer body 10a. However, the location of the operation panel 12 is not particularly limited. The operation panel 12 is used, for example, by an operator to perform printing-related operations. Although not shown, the operation panel 12 is equipped with a display unit that displays printing-related information such as resolution and ink density, as well as the status of the printer 10 during printing, and an input unit for inputting printing-related information.

[0015] The platen 16 supports the recording medium 5 when printing on the recording medium 5. The recording medium 5 is placed on the platen 16. Printing on the recording medium 5 is performed on the platen 16. As shown in FIG. 1, the platen 16 extends in the main scanning direction Y. The platen 16 is supported by the printer main body 10a. The platen 16 has a placement surface 16A (see FIG. 2) on which the recording medium 5 is placed, and a cutter protection member 17 (see FIG. 2) against which the tip of a sheet cutter 33 (see FIG. 3), described below, is pressed. The placement surface 16A is formed flat. In this embodiment, the placement surface 16A is black, but the color of the placement surface 16A is not limited to black. The recording medium 5 is placed on the placement surface 16A of the platen 16 before printing on the recording medium 5. As shown in FIG. 4, the cutter protection member 17 extends in the main scanning direction Y. As shown in FIG. 2, the cutter protection member 17 is replaceably fitted into a groove 16D formed in the mounting surface 16A. The cutter protection member 17 is provided behind an ink head 24 (which will be described later) (i.e., upstream in the sub-scanning direction X) and in front of a grit roller 57 (i.e., downstream in the sub-scanning direction X). The cutter protection member 17 has the function of protecting the tip (cutting edge) of the sheet cutter 33. The cutter protection member 17 is made of a resin material (for example, a polyolefin resin material such as polyethylene). In this embodiment, the cutter protection member 17 is black, but the color of the cutter protection member 17 is not limited to black.

[0016] As shown in FIG. 1, the printer 10 has a central wall 14 that extends in the main scanning direction Y and the up-down direction. The central wall 14 is supported by the printer body 10a. The central wall 14 is disposed above a platen 16. A gap is formed between the central wall 14 and the platen 16, allowing the recording medium 5 to pass through. As shown in FIG. 2, the printer 10 has a guide rail 15. The guide rail 15 extends in the main scanning direction Y. The guide rail 15 is provided on the central wall 14. The guide rail 15 is disposed above the platen 16.

[0017] As shown in FIG. 3, the ink head unit 20 includes a carriage 28, multiple ink heads 24, an optical sensor 31, and a sheet cutter 33. The carriage 28 is engaged with the guide rail 15. The carriage 28 is configured to be movable in the main scanning direction Y along the guide rail 15. The carriage 28 is equipped with the ink heads 24, the optical sensor 31, and the sheet cutter 33. The ink heads 24, the optical sensor 31, and the sheet cutter 33 are configured to be movable in the main scanning direction Y as the carriage 28 moves. The ink heads 24 eject ink onto the recording medium 5 placed on the platen 16 and have multiple nozzles (not shown) aligned in the sub-scanning direction X. The ink heads 24 print a predetermined image on the recording medium 5. As shown in FIG. 3, five ink heads 24 are mounted on the carriage 28. However, the number of ink heads 24 is not limited to five.

[0018] The optical sensor 31 is provided so as to be movable in the main scanning direction Y over the recording medium 5 placed on the platen 16 and a suppression member 90 (see FIG. 4 ), which will be described later. The optical sensor 31 emits light and receives reflected light. The optical sensor 31 emits light onto the suppression member 90 and receives light reflected by the suppression member 90. The optical sensor 31 emits light onto the platen 16 (more specifically, the placement surface 16A or the cutter protection member 17) through the transparent recording medium 5 and receives light reflected by the platen 16. The type of the optical sensor 31 is not particularly limited, but examples include a reflective photosensor. In this embodiment, the optical sensor 31 is a color sensor (typically a color sensor that measures RGB values). The optical sensor 31 is connected to the control device 80. When the optical sensor 31 emits light onto the placement surface 16A of the platen 16, the attachment position of the optical sensor 31 is aligned with the placement surface 16A in the sub-scanning direction X. That is, when the optical sensor 31 moves in the main scanning direction Y, the optical sensor 31 passes over (preferably directly above) the placement surface 16A and the suppression member 90. Furthermore, when the optical sensor 31 irradiates light onto the cutter protection member 17 of the platen 16, the attachment position of the optical sensor 31 is aligned with the cutter protection member 17 in the sub-scanning direction X. That is, when the optical sensor 31 moves in the main scanning direction Y, the optical sensor 31 passes over (preferably directly above) the cutter protection member 17 and the suppression member 90.

[0019] As shown in FIG. 3, the sheet cutter 33 is configured to be able to cut the recording medium 5 placed on the platen 16 only in the main scanning direction Y. The sheet cutter 33 is configured to be able to move in the vertical direction. When not cutting the recording medium 5 (for example, during printing), the sheet cutter 33 rises and moves away from the recording medium 5 and the cutter protection member 17. On the other hand, when cutting the recording medium 5 (for example, at the end of printing), the sheet cutter 33 descends and comes into contact with the recording medium 5 and the cutter protection member 17. The sheet cutter 33 is controlled by the control device 80. When cutting the recording medium 5, the sheet cutter 33 moves in the main scanning direction Y while pressing its tip against the cutter protection member 17.

[0020] The carriage movement mechanism 40 moves the carriage 28 of the ink head unit 20 in the main scanning direction Y relative to the recording medium 5 placed on the platen 16. The carriage movement mechanism 40 moves the carriage 28 in the main scanning direction Y. The configuration of the carriage movement mechanism 40 is not particularly limited. As shown in FIG. 1, the carriage movement mechanism 40 includes a first pulley 41, a second pulley 42, an endless belt 43, and a carriage motor 44. The first pulley 41 is provided on the left end of the guide rail 15. The second pulley 42 is provided on the right end of the guide rail 15. The belt 43 is wound around the first pulley 41 and the first pulley 41. The belt 43 is fixed to the upper rear surface of the carriage 28 (see also FIG. 3). The second pulley 42 is connected to the carriage motor 44. However, the carriage motor 44 may be connected to the first pulley 41. Here, when the carriage motor 44 is driven, the second pulley 42 rotates, causing the belt 43 to run between the first pulley 41 and the second pulley 42. This causes the carriage 28 to move in the main scanning direction Y. In other words, the carriage motor 44 moves the carriage 28 in the main scanning direction Y. The carriage motor 44 is controlled by the control device 80.

[0021] The medium moving mechanism 55 moves the recording medium 5 placed on the platen 16 in the sub-scanning direction X relative to the carriage 28. The medium moving mechanism 55 moves the recording medium 5 placed on the platen 16 in the sub-scanning direction X. As shown in FIG. 1, the medium moving mechanism 55 includes a grit roller 57, a feed motor 58 (see FIG. 5), a pinch roller 60, and a holding shaft 64.

[0022] As shown in FIG. 1, the grit roller 57 is provided on the platen 16. The grit roller 57 is embedded in the platen 16 so that the top of the grit roller 57 is exposed to the outside. The grit rollers 57 are aligned in the main scanning direction Y. The grit roller 57 is disposed below the pinch roller 60. The grit roller 57 sandwiches the recording medium 5 between itself and the pinch roller 60. A feed motor 58 (see FIG. 5) is connected to the grit roller 57. The feed motor 58 is controlled by the control device 80. In other words, the grit roller 57 is controlled by the control device 80. When the feed motor 58 is driven to rotate the grit roller 57 while the recording medium 5 is sandwiched between the grit roller 57 and the pinch roller 60, the recording medium 5 is transported in the sub-scanning direction X.

[0023] 1, the pinch roller 60 is disposed above the platen 16. The pinch roller 60 is disposed below the guide rail 15. The pinch roller 60 is disposed in a position opposite the grit roller 57. The pinch roller 60 presses down on the recording medium 5 placed on the platen 16 from above.

[0024] 1, the holding shaft 64 extends in the main scanning direction Y. The holding shaft 64 holds the pinch roller 60. By rotating the holding shaft 64 about its axis, the pinch roller 60 can be moved toward or away from the grit roller 57. The holding shaft 64 is rotatably supported by the printer main body 10a.

[0025] As shown in FIG. 4, the printer 10 is equipped with a suppression member 90 that suppresses lifting of the recording medium 5 placed on the platen 16. The suppression member 90 includes a right suppression member 90R that suppresses lifting of the right edge of the recording medium 5, and a left suppression member 90L that suppresses lifting of the left edge of the recording medium 5. The right suppression member 90R and the left suppression member 90L are symmetrical in plan view with respect to a line extending in the front-to-rear direction (i.e., the sub-scanning direction X). The right suppression member 90R and the left suppression member 90L are provided so as to be movable in the main scanning direction Y relative to the platen 16. That is, the right suppression member 90R and the left suppression member 90L are configured so that their positions relative to the platen 16 can be changed depending on the length of the recording medium 5 in the main scanning direction Y (i.e., the width direction). The right suppression member 90R and the left suppression member 90L are disposed in front of the cutter protection member 17 (i.e., downstream in the sub-scanning direction X). Portions (here, rear ends) of the right-side suppression member 90R and the left-side suppression member 90L overlap with portions (here, front ends) of the cutter protection member 17. Portions of the right-side suppression member 90R and the left-side suppression member 90L are disposed above the recording medium 5. For example, the left portion of the right-side suppression member 90R is disposed above the right end 5R of the recording medium 5, and the right portion of the left-side suppression member 90L is disposed above the left end 5L of the recording medium 5. The right-side suppression member 90R and the left-side suppression member 90L function to suppress deviation (i.e., skewing) of the recording medium 5 in the main scanning direction Y. In this embodiment, the length from the left edge 90RL of the right-side suppression member 90R to the right edge 90LR of the left-side suppression member 90L corresponds to the length LX of the printing area of ​​the recording medium 5 in the main scanning direction Y. In other words, here, the length LX of the printing area of ​​the recording medium 5 in the main scanning direction Y is shorter than the length LY of the recording medium 5 in the main scanning direction Y. In this embodiment, the suppression member 90 is silver because it is made of aluminum, but the color of the suppression member 90 is not limited to silver as long as it is different from the color of the platen 16 (i.e., the mounting surface 16A and the cutter protection member 17). The color of the suppression member 90 is different from the color of the platen 16. In other words, the light reflectance of the suppression member 90 is different from the light reflectance of the platen 16.

[0026] As shown in FIG. 5, the overall operation of the printer 10 is controlled by a control device 80. The configuration of the control device 80 is not particularly limited. The control device 80 is, for example, a microcomputer. The hardware configuration of the microcomputer is not particularly limited, but it may include, for example, an interface (I / F) that receives print data and the like from an external device such as a host computer, a central processing unit (CPU) that executes instructions from a control program, a read-only memory (ROM) that stores the program executed by the CPU, a random access memory (RAM) used as a working area for expanding the program, and a storage device such as a memory that stores programs and various data. As shown in FIG. 1, the control device 80 is provided inside the printer main body 10a. However, the control device 80 does not have to be provided inside the printer main body 10a. For example, the control device 80 may be a computer or the like installed outside the printer main body 10a. In this case, the control device 80 is connected to the printer 10 so as to be able to communicate with it via a wired or wireless connection.

[0027] 5, the control device 80 is communicatively connected to the ink head 24, feed motor 58, carriage motor 44, optical sensor 31, and sheet cutter 33. The control device 80 controls the ink head 24, feed motor 58, carriage motor 44, optical sensor 31, and sheet cutter 33. In other words, the control device 80 controls the carriage movement mechanism 40 and the medium movement mechanism 55.

[0028] The control device 80 measures the length LX (see FIG. 4) in the main scanning direction Y of the printing area of the recording medium 5 based on the detection result of the optical sensor 31. The control device 80 measures the length LX in the main scanning direction Y of the printing area of the recording medium 5 based on the first light reception amount of the light reflected by the right suppression member 90R and the left suppression member 90L when the optical sensor 31 moves in the main scanning direction Y while irradiating light and the second light reception amount of the light transmitted through the recording medium 5 and reflected by the platen 16. Note that the first light reception amount of the light reflected by the right suppression member 90R and the first light reception amount of the light reflected by the left suppression member 90L are substantially the same. The control device 80, for example, when the optical sensor 31 moves from one side to the other (for example, from the left side to the right side) in the main scanning direction Y while irradiating light, sets the position where the change occurs from the first light reception amount to the second light reception amount as one end (for example, the left end) in the main scanning direction Y of the printing area, and sets the position where the change occurs from the second light reception amount to the first light reception amount as the other end (for example, the right end) in the main scanning direction Y of the printing area, and measures the length LX in the main scanning direction Y of the printing area. The control device 80 of the present embodiment converts the first light reception amount and the second light reception amount into voltages, determines it as the suppression member 90 when the voltage is equal to or higher than the threshold value Vth, and determines it as the platen 16 when the voltage is less than the threshold value Vth. For example, when the platen 16 is black and the suppression member 90 is silver, the first light reception amount > the second light reception amount (the light reception amount is approximately zero in the case of black), so the voltage in the suppression member 90 becomes higher. For example, in the example shown in FIG. 6, the control device 80 determines that the section from position 0 to position L0 is the platen 16 because the voltage is 0 (<Vth), determines that the section from position L0 to position L'sub>1 is the left suppression member 90L because the voltage is V (≧Vth), determines that the section from position L'sub>1 to position L'sub>2 is the platen 16 because the voltage is 0 (<Vth), determines that the section from position L'sub>2 to position L'sub>3 is the right suppression member 90R because the voltage is V (≧Vth), and determines that the section beyond position L'sub>3 is the platen 16 because the voltage is 0 (<Vth). That is, the control device 80 measures the length LX in the main scanning direction Y of the printing area from the difference between position L'sub>2 and position L'sub>1. Note that the portion where light is irradiated from the optical sensor 31 may be the placement surface 16A of the platen 16 or the cutter protection member 17. When light is irradiated onto the placement surface 16A, the light reception amount of the light reflected by the placement surface 16A is the second light reception amount.When light is irradiated onto the cutter protection member 17, the amount of light received that is reflected by the cutter protection member 17 is the second amount of light received. After measuring the length LX of the print area in the main scanning direction Y, the control device 80 stores the length LX. In this way, the printer 10 can automatically measure the length LX of the print area in the main scanning direction Y even when a transparent recording medium 5 is used, eliminating the need for the user to visually measure the length LX and input the value into the printer 10.

[0029] As described above, in the printer 10 of this embodiment, the color of the platen 16 is different from the color of the suppression member 90. In other words, the reflectance of the platen 16 is different from the reflectance of the suppression member 90. As a result, a clear difference occurs between the first received light amount of light reflected by the suppression member 90 and the second received light amount of light that is transmitted through the recording medium 5 and reflected by the platen 16. This allows the control device 80 to grasp, for example, the transition points (e.g., positions L1 and L2) between the first received light amount and the second received light amount, and to measure the length LX of the print area of ​​the recording medium 5 in the main scanning direction Y.

[0030] In the printer 10 of this embodiment, the control device 80 measures the length LX of the print area in the main scanning direction Y by determining the position L1 where the received light intensity changes from the first to the second as the end of the print area in the main scanning direction Y when the optical sensor 31 moves from one side to the other in the main scanning direction Y while emitting light, and the position L2 where the received light intensity changes from the second to the first as the end of the print area in the main scanning direction Y. When the optical sensor 31 moves from one side to the other in the main scanning direction Y, the optical sensor 31 moves over the left suppression member 90L, the platen 16, and the right suppression member 90R in this order. Therefore, the amount of received light at the optical sensor 31 changes in the order of the first received light intensity, the second received light intensity, and the first received light intensity again. In other words, the ends of the print area in the main scanning direction Y can be recognized as the transition points between the first and second received light intensities (e.g., positions L1 and L2), making it easy to measure the length LX of the print area in the main scanning direction Y.

[0031] In the printer 10 of this embodiment, the second received light amount is the received light amount reflected by the flat mounting surface 16A on which the recording medium 5 is placed. By making the color of at least the mounting surface 16A of the platen 16 different from the color of the suppression member 90, a clear difference can be created between the first received light amount of light reflected by the suppression member 90 and the second received light amount of light that passes through the recording medium 5 and is reflected by the mounting surface 16A.

[0032] In the printer 10 of this embodiment, the placement surface 16A is black. Because the light irradiated from the optical sensor 31 is hardly reflected by the black placement surface 16A, the difference between the amount of light reflected by the suppression member 90 and the amount of light received becomes significant, making it easier to grasp the transition points (for example, positions L1 and L2) between the first and second received light amounts.

[0033] In the printer 10 of this embodiment, the platen 16 includes a cutter protection member 17 that extends in the main scanning direction Y and against which the tip of the sheet cutter 33 is pressed, and the second amount of received light is the amount of light reflected by the cutter protection member 17. The cutter protection member 17 is usually provided only around the portion of the platen 16 through which the tip of the sheet cutter 33 passes, so it is easy to make the color of the cutter protection member 17, relative to the color of the suppression member 90, more clearly different from the color of other portions of the platen 16 (for example, the mounting surface 16A).

[0034] In the printer 10 of this embodiment, the cutter protection member 17 is black. Because the light irradiated from the optical sensor 31 is hardly reflected by the black cutter protection member 17, the difference between the amount of light reflected by the suppression member 90 and the amount of light received becomes significant, making it easier to grasp the transition points (for example, positions L1 and L2) between the first and second received light amounts.

[0035] Although the preferred embodiments of the present invention have been described above, the above-described embodiments are merely examples, and the present invention can be embodied in various other forms.

[0036] In the above-described embodiment, the optical sensor 31 is mounted on the carriage 28 on which the ink head 24 is mounted, but this is not limiting. For example, the printer 10 may include a separate carriage that is movable independently of the carriage 28, and the optical sensor 31 may be mounted on the separate carriage. [Explanation of symbols]

[0037] 5. Recording media 10 Printer (inkjet printer) 16 Platen 16A Placement surface 17 Cutter protection member 24 ink head 31 Optical Sensor 33 Sheet cutter 80 Control device 90 Restraining member

Claims

1. a platen on which a transparent recording medium is placed; an ink head that ejects ink onto the recording medium placed on the platen and is provided so as to be movable in a main scanning direction; a pair of suppression members that are provided movably in the main scanning direction relative to the platen and that suppress lifting of both ends of the recording medium placed on the platen in the main scanning direction; an optical sensor that is provided to be movable in the main scanning direction over the recording medium placed on the platen and the suppressing member, and that irradiates light and receives reflected light; a control device connected to the optical sensor; a sheet cutter that is provided so as to be movable in the main scanning direction and that is capable of cutting the recording medium only in the main scanning direction, the recording medium is configured to be transported from the upstream side to the downstream side in a sub-scanning direction perpendicular to the main scanning direction in a plan view, the platen includes a cutter protection member that extends in the main scanning direction and against which a tip of the sheet cutter is pressed, the cutter protection member is disposed upstream of the ink head in the sub-scanning direction, The color of the platen is different from the color of the suppression member. the suppression member is made of aluminum and is silver in color; the cutter protection member is made of a polyolefin resin material and is black in color; The control device measures the length of the printing area of ​​the recording medium in the main scanning direction based on a first received amount of light reflected by the pair of suppression members when the optical sensor moves in the main scanning direction while irradiating light, and a second received amount of light that passes through the recording medium and is reflected by the cutter protection member.

2. 2. The inkjet printer according to claim 1, wherein the control device measures the length of the print area in the main scanning direction by defining a position where the amount of received light changes from the first amount to the second amount as one end of the print area in the main scanning direction when the optical sensor moves from one side to the other in the main scanning direction while irradiating light, and defining a position where the amount of received light changes from the second amount to the first amount as the other end of the print area in the main scanning direction.

3. The inkjet printer according to claim 1 , wherein the cutter protection member is made of polyethylene.

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