JP6417285B2 - inkjet printer - Google Patents

Description

  The present invention relates to an ink jet printer that records an image on a recording medium.

  Inkjet printers that record images by ejecting ink from an inkjet recording head onto a recording medium have become widespread. The ink stored in the ink cartridge is supplied to the recording head, and the ink is ejected from the nozzle of the recording head. This type of printer is not only a small one used at home for recording on A4 or A3 size paper, but also a large one that can print on a wide recording medium exceeding 1 meter wide. Widely used.

  There are various inks used for recording. For example, there are an ink in which a dye is dissolved in a solvent such as water, a solvent ink in which a pigment is dispersed in an organic solvent, an ultraviolet curable ink that is cured by ultraviolet rays, and a thermosetting ink that is cured by heat.

  Also, in an ink jet printer, a recording head is mounted on a carriage that reciprocates in the width direction of the recording medium, that is, in the main scanning direction, and ink is ejected onto the recording medium in the forward path and the backward path to record an image. The recording medium is conveyed in a direction orthogonal to the carriage movement direction, that is, in the sub-scanning direction. The print head is divided into multiple equal blocks, for example, 4 equal blocks, the print medium is conveyed according to the width, the ink is ejected while moving the carriage in the main scanning direction, and the same area is divided into multiple blocks by different blocks. There are also recordings by a method such as a multi-pass method for recording by scanning. The position of the carriage is read by a sensor mounted on the carriage with a linear scale provided along the moving direction of the carriage to obtain the position of the carriage. In general, a device called a linear encoder is used. Further, an image is recorded by adsorbing the recording medium to a flat platen having a width equal to or larger than the length of the nozzle row of the recording head, keeping the recording medium flat, and ejecting ink thereto. By keeping it flat, image quality disturbance is suppressed. Based on the position of the carriage measured by the linear encoder, by ejecting ink onto a recording medium that is kept flat, it is possible to record an image under stable conditions, enabling high-quality recording. ing.

  However, wrinkles may occur on the recording medium supported by the platen, and the wrinkles cause ink to flow or dry, resulting in poor quality of the recorded image or damage when the recording head collides. Or caused a jam.

  Therefore, for example, the technique described in Japanese Patent Application Laid-Open No. 2012-228778 discloses a rotating unit that is rotatably fixed to an ink head that moves in a main scanning direction orthogonal to a conveyance direction of a recording medium, Detection means for detecting rotation of the rotation means is provided. When the rotating unit comes into contact with the recording medium, it is possible to detect that the distance between the ink head and the recording medium is close by detecting the rotation of the rotating unit with the detecting unit. The ink head is prevented from being damaged by stopping the movement of the ink head when rotation is detected by the detecting means.

JP 2012-228778 A

However, the conventional apparatus detects the rotation of the rotation means to detect that the distance from the recording medium is less than a certain value, and performs processing such as stopping.
However, since the rotating means is fixed in the vicinity of the ink head, ink may scatter and adhere to the rotating part, or ink mist may adhere. When the ink adheres, there is a possibility that a larger force is required for rotation, and in the worst case, the ink is solidified and the rotation means may not move. In such a case, there is a risk of erroneous detection or detection failure. Further, the detection by the rotating means has a problem that the thin rotating piece is in contact with the recording medium, and therefore cannot be detected simultaneously in a wide area.

  Therefore, the present invention provides a printer that can prevent erroneous detection or detection failure by detecting that the recording medium is too close to the recording head in a wide area without having a rotating means. .

The inkjet printer according to the present invention includes a plurality of nozzles, a recording head that discharges ink from the nozzles toward the recording medium, a platen that supports the recording medium, a conveying unit that conveys the recording medium, A carriage mounted with a recording head and moving in a main scanning direction orthogonal to the conveyance direction of the recording medium, a recording medium detection sensor, and the carriage, the recording head based on the detection result of the recording medium detection sensor Control means for controlling the operation of the conveying means, and the ink is ejected from the recording head onto the recording medium supported by the platen to record an image.
A side surface of the carriage in the main scanning direction and a height from the platen is arranged at a predetermined distance, and a flexible detection plate that is bent by contact with the recording medium and a position of the carriage are detected. A carriage position detection sensor.
The recording medium detection sensor includes a detection sensor that is fixed to the detection plate and outputs a signal according to the bending of the detection plate when the detection plate contacts the recording medium.
The side of the detection plate that faces the platen is divided into a plurality of slits, and the detection sensor is disposed in each of the divided portions.
Further, the control means is arranged at the portion that is in contact with the recording medium when any of the plurality of the divided portions of the detection plate is in contact with the recording medium while the carriage is moving in the recording area. The detected sensor outputs a signal, and the movement of the carriage is controlled based on the output of the signal and the position of the carriage acquired by the position detection sensor.

  According to the present invention, when the recording medium gets too close to the carriage on which the recording head is mounted, the sensor detects, changes the operation of the carriage, prevents damage to the recording head, and prevents jamming. It can be performed.

FIG. 1 is a view from the side of the carriage. FIG. 2 is a block diagram of the printer. FIG. 3 is a diagram for explaining an example of the maintenance unit of the recording head. FIG. 4 is a diagram illustrating the detection signal. FIG. 5 is a diagram for explaining signal detection. FIG. 6 is a flowchart for explaining the test operation. FIG. 7 is a diagram illustrating an overview of the entire printer.

Embodiments will be described below with reference to the drawings.
FIG. 1 is a view from the side of the carriage. The carriage 1 is movably fixed to a rail disposed along the platen 15. In this figure, the rail is not shown, but the carriage 1 moves in the depth direction of the paper. The rails are arranged along the longitudinal direction of the ink jet printer, and the carriage 1 can move along the rails. The detection plate 3 is fixed to the side surface of the carriage 1. Although only one side will be described here, it is provided on both sides. When the detection plate 3 comes into contact with the recording medium, bending or distortion occurs, and this deformation is detected by the first sensor 9, the second sensor 10, and the third sensor 11 which are detection sensors fixed to the detection plate 3. To do. For example, these sensors include a piezoelectric element, generate electricity by being deformed, and output a signal. There is a paper guide 16 on the downstream side in the transport direction of the recording medium transported on the platen 15.

  The carriage 1 is provided with an up-and-down mechanism 2 that moves the carriage 1 up and down in the direction of the platen 15 with respect to the rail. Here, the direction approaching the platen 15 will be described as a downward direction, and the direction away from the platen 15 will be described as an upward direction. The vertical mechanism 2 can change the distance in the vertical direction between the carriage 1 and the platen 15 or the recording medium supported on the platen 15. A distance sensor 12 is provided to measure the distance to the platen 15. The distance between the carriage 1 and the platen 15 or the recording medium can be acquired by measuring the length of the distance sensor 12 moved up and down from the reference position. For example, the position of the edge 13 on the side facing the platen 15 of the detection plate 3 is set as the first reference. The detection plate 3 is provided for detecting the presence or absence of irregularities caused by wrinkling or twisting of the recording medium. First, the vertical distance from the edge 13 to the platen 15 or the recording medium without distortion is measured first. The carriage 1 is scanned and the output of the detection plate 3 is acquired. Further, the thickness of the recording medium can be obtained from the difference between the distance from the reference position to the platen 15 and the distance to the recording medium.

  A signal is output from the detection plate 3 when the detection plate 3 contacts the recording medium. In this case, it can be seen that there is a protruding portion of the recording medium. If no signal is output from the detection plate 3, the recording medium is not in contact with the detection plate 3. In this case, it can be seen that there is only unevenness smaller than the distance in the vertical direction to the recording medium initially measured.

  The height of the carriage 1 also affects the image quality. The distance between the nozzle surface of the recording head and the recording medium may or may not be too close, and it is necessary to set a suitable distance. In accordance with the first reference, the carriage 1 needs to be moved up and down and set to a suitable distance. Furthermore, it is preferable that the edge 13 and the nozzle surface have the same vertical distance from the platen 15 so that the nozzle surface does not contact the recording medium. A state in which the nozzle surface protrudes from the edge 13 is not so preferable.

The guard 14 is a reinforced portion for protecting the carriage 1 when a jam occurs. A portion that cannot be detected is reinforced by the detection plate 3. The detection plate 3 needs at least a width corresponding to the recording head, preferably a width corresponding to the platen 15. The wiring 18 is an electrical wiring that connects the first sensor 9, the second sensor 10, the third sensor 11 and the control means. Wiring enters the carriage 1 and is connected to the control means.
A recording head and a nozzle surface are provided on the side of the carriage 1 facing the platen 15. In the figure, it is not shown because it is behind the detection plate 3.

  By the first slit 4 and the second slit 5, the edge 13 side of the detection plate 3 is divided into a first plate piece 6, a second plate piece 7, and a third plate piece 8. A first sensor 9 is disposed on the first plate piece 6, a second sensor 10 is disposed on the second plate piece 7, and a third sensor 11 is disposed on the third plate piece 8. Each sensor reacts when each piece is distorted. There is a fixed plate 17 in the vicinity of the end of the slit separating the detection plate 3, and the detection plate 3 and the sensor are fixed to the carriage 1. Thereby, detection becomes possible for every board piece. Moreover, although the width | variety of each board piece may be made the same, Preferably, the width | variety of each board piece is made into a different width | variety. For example, the width of the plate on the downstream side in the conveyance direction of the recording medium is reduced and the upstream side is increased. By doing in this way, since the frequency which an unevenness | corrugation changes with places, it is preferable to change the width | variety of a board piece according to the frequency according to a place. Since the conveyance roller is close to the upstream side in the conveyance direction of the recording medium, irregularities that cause jamming are unlikely to occur.

  The detection plate 3 is resistant to ink, and is preferably a PET resin having high processability and durability. In addition, when the first sensor 9, the second sensor 10, and the third sensor 11 are fixed to the detection plate 3, when considering replacement, it is possible to make a recess in the detection plate 3 and insert each sensor there. Conceivable. The first sensor 9, the second sensor 10, and the third sensor 11 can be bonded to the detection plate 3.

  Here, an example of three sensors has been described, but it is also possible to arrange one sensor with respect to the detection plate 3. By using a plurality of, for example, three sensors, if any one of them reacts, control such as stopping the carriage 1 can be performed. Depending on the position at which the sensor is arranged with respect to the detection plate 3, a time lag may occur, and a plurality of sensors are arranged to accelerate the reaction.

  FIG. 2 is a block diagram of the printer. The control unit 20 is a control unit including a CPU that executes processing operations such as calculation, control, determination, and setting. The control means 20 operates according to a control program stored in the ROM 29. The RAM 19 is used as a recording data buffer, a work area for processing by the control means 20, and the like. The carriage movement motor drive circuit 26 operates under the control of the control means 20 and drives a motor that moves the carriage 1. The carriage position detection sensor 27 is a sensor that detects the position of the carriage 1. A scale of a linear scale arranged along a rail on which the carriage 1 is movably fixed is detected by a linear sensor. The position of the carriage 1 can be calculated and acquired based on the sensor output. Based on this position, the carriage 1 can be controlled to move.

  The head drive circuit 28 is controlled by the control means 20. The recording head is operated via the head driving circuit 28. When a plurality of recording heads are mounted, the control unit 20 and the head driving circuit 28 can drive each recording head individually. The head drive circuit 28 generates ink ejection timing or non-ejection timing of each recording head based on the information input from the control unit 20 and drives the recording head. This timing is calculated based on the position of the carriage 1 acquired by the carriage position detection sensor 27. When ink is ejected, an on waveform is generated, and when ink is not ejected, an off waveform is generated and transferred to each recording head. The ejection timing is determined according to the position of the carriage 1.

  The recording medium transport unit 21 operates under the control of the control unit 20. The recording medium transport unit 21 includes a transport roller and a motor that drives the transport roller. The recording medium is conveyed by operating the conveying roller.

  The wipe unit lifting / lowering means 25 operates under the control of the control means 20. A wipe unit 30, which will be described later, can be moved in a direction toward and away from the recording head. For example, the motor that drives the cam is controlled by moving the cam up and down.

  The recording medium detection sensor 22 is a sensor that is fixed to the detection plate 3 including the first sensor 9, the second sensor 10, and the third sensor 11, and outputs a signal according to distortion. The recording medium detection sensor 22 operates under the control of the control means 20. Since the recording medium detection sensor 22 is fixed to the carriage 1, it is possible to detect unevenness of the recording medium in the moving range of the carriage 1.

  The distance sensor 12 is fixed to the carriage 1 and can measure the moving distance until the platen 15 comes into contact with the tip of a terminal that expands and contracts. Thereby, the distance from the reference position to the object can be measured. The distance sensor 12 operates under the control of the control means 20.

  The operation panel 23 operates under the control of the control means 20. The operation panel 23 is provided with an LCD panel, can perform various displays, and has a keyboard for input.

The carriage lifting / lowering means 24 can move the carriage 1 in the contact / separation direction with respect to the platen 15. The carriage lifting / lowering means 24 operates under the control of the control means 20. The control means 20 can control the carriage lifting / lowering means 24 based on the distance to the object acquired by the distance sensor 12 to raise and lower the carriage 1 so that the distance between the carriage 1 and the platen 15 can be set to a suitable distance. . By using the carriage lifting / lowering means 24, when the recording medium detection sensor 22 is tested, the carriage 1 can be moved to a height at which the carriage 1 can be brought into contact with the protrusion to be brought into contact with the recording medium detection sensor 22.
Each function of the ink jet printer is controlled by the control of the control means 20.

  FIG. 3 is a diagram for explaining an example of the maintenance unit of the recording head. The nozzle surface of the recording head is soiled by ink mist or the like. The nozzle surface is clogged due to dirt on the nozzle surface, causing problems such as non-ejection and flight bending. Also, if the ink near the nozzles thickens and oozes out without being ejected, the same problem occurs. Therefore, it is necessary to periodically wipe the nozzle surface with the wiper 35 and clean the nozzle surface. The wipe unit 30 is a unit provided with a wiper 35 for cleaning the nozzle surface of the recording head. The wiper 35 is disposed for each recording head. The wiper 35 is fixed to the belt, moves by rotating the belt, and wipes the nozzle surface. Below the wiper 35, a tank containing a cleaning liquid for removing dirt on the wiper 35 is disposed. The wiper 35 moves along with the rotation of the belt, removes dirt with this cleaning liquid, and can be made free of dirt when contacting the nozzle surface.

  The wipe unit 30 is moved up and down by the wipe unit lifting means 25. The wipe unit 30 is arranged at a position other than the recording area on the side of the platen 15. The wipe unit 30 is normally lowered to a position where the wiper 35 of the recording head does not come into contact. When wiping, the carriage 1 moves above the wipe unit 30. Next, the wipe unit lifting / lowering means 25 is controlled to move the wipe unit 30 toward the carriage 1. Next, the belt is rotated, and the nozzle surface is wiped by the wiper 35. When the wipe is completed, the rotation of the belt is stopped and the wipe unit 30 is lowered.

  The wipe unit 30 is provided with a detection protrusion 31 in addition to the wiper 35. The detection protrusion 31 is provided at the tip of the side wall of the wipe unit 30 in the moving direction of the carriage 1. The detection protrusion 31 can test the operation of the detection plate 3 by bringing the detection plate 3 into contact therewith. Since the wipe unit 30 can be moved up and down, the position of the detection protrusion 31 in the height direction can be changed. Tests at various locations are possible. The detection protrusion 31 is divided into a first protrusion 32, a second protrusion 33, and a third protrusion 34. This is because the first protrusion 32 is the first sensor 9 provided on the first plate piece 6, the second protrusion 33 is the second sensor 10 provided on the second plate piece 7, and the third protrusion 34 is the third plate piece 8. The third sensor 11 provided is divided so that it can be tested. Moreover, although the case where the front-end | tip of the detection protrusion 31 was divided | segmented corresponding to the sensor was made into the example, the method of not dividing the front-end | tip of the detection protrusion 31 is also considered.

  The detection protrusions 31 are disposed on both sides of the portion where the wiper 35 is disposed. If the detection plate 3 and the detection protrusion 31 can be relatively close to each other in the height direction, the detection protrusion 31 is disposed only on one side. But you can test it.

  Further, the first protrusion 32, the second protrusion 33, and the third protrusion 34 are arranged at different positions in the movement direction of the carriage 1, and the corresponding sensors can be individually tested as the carriage 1 moves. Yes.

  Here, the contact / separation means for relatively moving the detection projection 31 and the detection plate 3 relative to each other has been described by taking the case where the detection projection 31 is provided in the wipe unit 30 as an example. As another example, detection protrusions 31 are arranged on both ends of the movement range of the carriage 1. There is a method of controlling so as to move to a position where it abuts against the detection protrusion 31 only during a test and not to a position where it abuts against the detection protrusion 31 during a non-test. In this case, it is conceivable that the raising / lowering function is not provided on the detection protrusion 31, but it is possible to test whether at least the sensor operates. As another example, the wiper unit 30 is arranged such that the tip of the detection protrusion 31 is at the same height as the surface of the platen 15 that supports the recording medium. In this way, when the carriage 1 moves, the detection protrusion 31 and the detection plate 3 or the recording head do not contact each other. In the test, the carriage 1 is lowered using the carriage lifting / lowering means 24 to a height at which the detection plate 3 contacts the detection protrusion 31. Then, the carriage 1 is moved along the rail and brought into contact with it to test whether it can be detected by the recording medium detection sensor 22. By using the carriage lifting / lowering means 24, the lifting / lowering of the wipe unit 30 can be made unnecessary.

  FIG. 4 is a diagram illustrating the detection signal. FIG. 5 is a diagram for explaining signal detection. The detection signals of the first sensor 9, the second sensor 10, and the third sensor 11 will be described. The first sensor 9 is connected to the first signal conversion circuit 51, and the first signal conversion circuit is connected to the control means 20. The second sensor 10 is connected to the second signal conversion circuit 52, and the second signal conversion circuit is connected to the control means 20. The third sensor 11 is connected to the third signal conversion circuit 53, and the third signal conversion circuit is connected to the control means 20. The first sensor 9, the first signal conversion circuit 51, the second sensor 10, the second signal conversion circuit 52, the third sensor 11, and the third signal conversion circuit 53 correspond to the recording medium detection sensor 22.

  When the detection plate 3 is distorted and the first sensor 9 reacts, a signal is output. The signal waveform varies depending on the deformation size, speed, and direction of the first sensor 9. The input signal input to the first signal conversion circuit 50 from the first sensor 9 corresponds to the top signal diagram of FIG. The input signal 44 is a voltage displacement diagram in which the vertical direction changes in the positive and negative directions with respect to the reference potential 40 and the horizontal direction is time.

  The first signal conversion circuit 51 and the input signal 44 are cut by a positive threshold 41 and a negative threshold 42, and a rectified signal 46 that is a signal only on the positive side is generated through a full-wave rectifier circuit. A positive threshold 41 and a negative threshold 42 are set so as not to exceed the allowable voltage range of the subsequent circuit. The portion of the signal 45 that exceeds the plus threshold 41 is cut.

  The rectified signal 46 is further detected by the signal threshold value 43 to generate a rectangular wave 48. A portion of the signal 47 that exceeds the signal threshold 43 is detected, and a rectangular signal is generated. The rectangular wave 48 is used as a digital signal that can be input by the subsequent control means 20. The control means 20 acquires the position of the carriage 1 at the generation timing of the rectangular wave 48 and uses it for control. The fact that the rectangular wave 48 has been detected means that the recording medium has come into contact with the detection plate 3, and urgent control is performed. For example, the control means 4 performs control such as stopping and moving in the reverse direction. If the rectangular wave 48 is shorter than a predetermined time, that is, if it is a single signal having a high frequency, it can be controlled so that it is treated as noise.

  Although one sensor has been described here, the other sensors are similarly controlled. Further, although the example of three sensors has been described, it is also possible to arrange one sensor with respect to the detection plate 3. By using a plurality of, for example, three sensors, if any one of them reacts, control such as stopping the carriage 1 can be performed. Depending on the position at which the sensor is arranged with respect to the detection plate 3, a time lag may occur, and a plurality of sensors are arranged to accelerate the reaction.

FIG. 6 is a flowchart for explaining the test operation. First, in step S <b> 1, the carriage 1 is moved to above the wipe unit 30.
Next, in step S2, the height direction positions of the detection protrusion 31 and the detection plate 3 are set to the first test position. This is possible by testing the position of the detection projection 31 and the detection plate 3 in a plurality of stages while changing the position in the height direction and testing the displacement and deformation of the detection plate 3 in the height direction. For example, the relative position is changed by lowering the carriage 1 or raising the wipe unit 30.

Next, in step S3, the carriage 1 is moved so that the detection protrusion 31 and the detection plate 3 can be brought into contact with each other.
In step S4, the detection result is stored in the RAM 19 in association with the height position.
Next, in step S5, it is determined whether or not the test at the planned previous height position is completed. If completed, the process proceeds to step S6, and if not completed, the process proceeds to step S8.

In step S8, the position of the detection protrusion 31 and the detection plate 3 in the height direction is changed to the next test position, and then the process proceeds to step S3.
In step S6, the detection protrusion 31 and the detection plate 3 are separated from each other in the height direction, that is, returned to the initial position before the test, the test results at all height positions are investigated, and the sensor does not react. Determine if there is a condition. If there is an error state, the process proceeds to step S7, and if not, the process proceeds to step S9.

In step S7, since there is an error, the height position and sensor number where the error occurred are displayed on the operation panel 23, and the process is terminated.
In step S9, since there is no error, it is displayed on the operation panel 23 that there is no error and it is normal, and the process is terminated.
In this way, each sensor can be tested at various relative height positions and the results can be communicated.

  FIG. 7 is a diagram illustrating an overview of the entire printer. The ink jet printer 100 records an image by ejecting ink onto a recording medium adsorbed on the platen 15 while reciprocating the carriage 1 over the platen 15. The platen 15 is a flat plate, pores are formed in the plate, a suction chamber is disposed on the back side, air is drawn in, and the recording medium is supported by the force. A paper guide 16 is arranged in the conveyance direction of the recording medium of the platen 15 to heat the discharged recording medium and promote ink fixing. In addition, an air heater 101 is provided at a position facing the paper guide 16 to heat the recording medium and further promote ink fixing.

  A wipe unit 30 for cleaning the recording head mounted on the carriage 1 is provided on the side of the platen 15. The carriage 1 is moved to the position of the wipe unit 30 and the wipe unit 30 is moved in the direction of the carriage 1. The raising / lowering control is performed so that it can stop at the target position of the wipe unit 30. The wipe unit 30 moves upward to a position where the provided wiper 35 contacts the nozzle surface of the recording head. By moving the wiper 35, the nozzle surface can be wiped and cleaned. Further, the detection projection 31 provided in the wipe unit 30 can inspect the state of the detection sensor and display the result on the operation panel 23.

  Supported by the platen 15 and the paper guide 16, the recording medium is conveyed. Unevenness caused by distortion or bending of the recording medium is detected, and stopping and moving can be controlled so that the recording head mounted on the carriage 1 does not come into contact.

  The present invention can be applied to an ink jet printer.

DESCRIPTION OF SYMBOLS 1 Carriage 2 Vertical mechanism 3 Detection board 4 1st slit 5 2nd slit 12 Distance sensor 13 Edge 15 Platen 16 Paper guide 22 Recording medium detection sensor 30 Wipe unit 31 Detection protrusion 35 Wiper

Claims (5)

A plurality of nozzles, and a recording head that discharges ink from the nozzles toward a recording medium;
A platen that supports the recording medium;
Conveying means for conveying the recording medium;
A carriage mounted with the recording head and moving in a main scanning direction orthogonal to the conveyance direction of the recording medium ;
And the record medium detection sensor,
Control means for controlling the operation of the carriage, the recording head, and the conveying means based on the detection result of the recording medium detection sensor, and the recording head supported by the platen from the recording head to the recording medium. In an inkjet printer that discharges ink and records an image,
A flexible detection plate which is a side surface in the main scanning direction of the carriage and is arranged at a predetermined distance from the platen and is bent by contact with the recording medium;
Together with a carriage position detecting sensor for detecting a position of said carriage,
The recording medium detection sensor is fixed to the detection plate, consists detection sensor detecting plate to output a signal in response to deflection of the detection plate when in contact with the recording medium,
The side of the detection plate that faces the platen is divided into a plurality of slits, and the detection sensor is arranged in each of the divided parts,
The control means is disposed in the portion in contact with the recording medium when any of the plurality of the divided portions of the detection plate is in contact with the recording medium while the carriage is moving in the recording area . inkjet printer, wherein said detection sensor outputs a signal, that controls the movement of the front Symbol carriage based the output of the signal, and the position of the carriage obtained by the position detection sensor. The inkjet printer according to claim 1, wherein the detection plate and the detection sensor are fixed to a carriage by a fixed plate. A detection protrusion disposed on the outside of the platen and in contact with the detection plate;
By moving the carriage to the outside of the platen, by allowing abutment of said detection plate to said detector projections, inkjet printer according to claim 1, characterized in that to test the operation of the recording medium detection sensor. The detection protrusion is divided into a plurality of portions corresponding to the plurality of portions of the detection plate, and the divided portions of the detection protrusions are arranged with their positions in the main scanning direction shifted. The inkjet printer according to claim 3 . Inkjet printer according to any one of the preceding claims 1 wherein the control means by any one of the signals of the plurality arranged the detection sensor and controlling the movement of the carriage.

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