Printing apparatus, control method, storage medium, and computer program product

Abstract

The invention relates to a printing apparatus, a control method, a storage medium, and a computer program product. The printing apparatus includes: a carriage movable in a width direction intersecting a conveyance direction; a first detection unit provided on one side of the carriage in the width direction and capable of detecting an end portion of the printing medium; and a second detection unit disposed on the other side of the carriage in the width direction and capable of detecting the end portion, at least one of the first detection unit and the second detection unit including: a light emitting unit configured to emit light to the platen and the printing medium; a first light receiving unit capable of receiving reflected light from the platen and the printing medium; and a second light receiving unit capable of receiving reflected light from the platen and the printing medium, overlapping the first light receiving unit in the conveyance direction, and spaced apart from the first light receiving unit in the width direction.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a printing apparatus and a control method. BACKGROUND

[0002] Assume a case where a printing apparatus configured to perform printing on a print medium by ejecting ink using an inkjet method performs marginless printing in which printing is performed without setting a margin in an end portion of the print medium. In this case, if the accuracy of detecting the end portion position of the print medium is low, the low detection accuracy causes contamination in the apparatus and formation of a margin. Japanese Patent Application Publication No. 2004-182361 discloses a technique of detecting the end portion position of a print medium based on a detection signal generated from reflected light from the print medium using a single detection portion.

[0003] However, in the technique of Japanese Patent Application Publication No. 2004-182361, in a case where both end portions of the print medium in the scanning direction are detected using the detection portion provided on one side of the scanning direction of the print head, it is necessary to set a wide scanning range, and this increases the period required for printing. SUMMARY

[0004] The present disclosure is made in view of the above problems, and provides a technique that can suppress an increase in the period required for printing.

[0005] A printing apparatus according to some embodiments includes a support unit configured to support a conveyed print medium; a carriage in which a print head configured to perform printing by ejecting ink to the print medium is installed, the carriage being movable in a width direction of the print medium intersecting a conveyance direction of the print medium; a first detection unit provided on one side of the carriage in the width direction and capable of detecting an end portion of the print medium in the width direction; and a second detection unit provided on the other side of the carriage in the width direction and capable of detecting an end portion of the print medium in the width direction, wherein at least one of the first detection unit and the second detection unit includes an emission unit configured to emit light to the support unit and the print medium supported on the support unit; a first light-receiving unit capable of receiving reflected light from the support unit and the print medium supported on the support unit; and a second light-receiving unit capable of receiving reflected light from the support unit and the print medium supported on the support unit, the second light-receiving unit overlapping the first light-receiving unit in the conveyance direction and being spaced apart from the first light-receiving unit in the width direction.

[0006] The features of the present disclosure will become apparent from the following description of the embodiments with reference to the accompanying drawings. The following description of the embodiments is described by way of example with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a block diagram of a printing device.

[0008] Figure 2A and Figure 2B is a schematic configuration diagram of a printing unit.

[0009] Figure 3A and Figure 3B is a schematic configuration diagram of a first sensor and a second sensor.

[0010] Figure 4 is a block diagram focusing on the configuration of a control system of a printing device.

[0011] Figures 5A-5C is a graph illustrating a change in an output voltage of a first sensor.

[0012] Figure 6 is a graph illustrating an output waveform exemplifying a change in an output voltage of a first sensor.

[0013] Figure 7 is a graph illustrating an operation of a second sensor in a differential mode.

[0014] Figures 8A-8C is a graph illustrating an output voltage in one of light-receiving portions of a second sensor in a differential mode.

[0015] Figure 9 is a graph illustrating an output waveform exemplifying a change in a differential signal in a differential mode.

[0016] Figure 10 is a graph illustrating a change in an output voltage of a second sensor in a single mode.

[0017] Figure 11 is a flowchart exemplifying details of a printing process.

[0018] Figure 12 (A) to Figure 12 (L) of FIG. 12 are graphs illustrating detection of an end position of a print medium at the time of scanning involved in printing.

[0019] Figure 13 is a graph exemplifying an outline of determination of an end position of a print medium.

[0020] Figure 14 is a flowchart exemplifying details of an obtaining process.

[0021] Figure 15A andFigure 15B is a graph illustrating the size of a printed image with respect to a print medium in micro-edge printing.

[0022] Figure 16A and Figure 16B is a graph illustrating a change in the moving speed of the first sensor at the time of passing through the end portion.

[0023] Figure 17A and Figure 17B is a graph illustrating an outline of a change in the stop position of the carriage.

[0024] Figure 18 is a flowchart illustrating details of the change processing.

[0025] Figure 19 is a flowchart illustrating details of a modification example of the change processing.

[0026] Figure 20A and Figure 20B is a graph illustrating a condition in which no change in the moving speed occurs in a unit of scanning involved in printing.

[0027] Figure 21 is a graph illustrating an example of data for indicating a relationship between a correction amount and a moving speed difference.

[0028] Figure 22A and Figure 22B is a graph illustrating a detection technique of the end portion position of the print medium in response to unnecessary output.

[0029] Figure 23 is a graph illustrating a detection technique of the end portion position of the print medium in response to unnecessary output.

[0030] Figures 24A-24D is a graph illustrating a detection technique of the end portion position of the print medium in response to unnecessary output.

[0031] Figure 25A and Figure 25B is a graph illustrating a detection technique of the end portion position of the print medium in response to abnormal output. DETAILED DESCRIPTION

[0032] Examples of embodiments of a printing apparatus and a control method will be described in detail below with reference to the accompanying drawings. Note that the following embodiments do not limit the present disclosure, and not all combinations of features described in the present embodiments are necessarily essential to the means for solving the problems of the present disclosure. Furthermore, the positions and shapes of constituent elements described in the embodiments are merely examples, and are not intended to limit the scope of the present disclosure to these positions and shapes.

[0033] (First Embodiment)

[0034] First, reference will be made toFigures 1-12 (L) to describe the printing device according to the first embodiment in detail.

[0035] <Configuration of printing device>

[0036] Figure 1 is a perspective view of a printing device. Figure 2A and Figure 2B is a view illustrating a configuration of a printing unit provided inside the printing device, Figure 2A is a plan view, and Figure 2B is a front view. In the present specification, the description is given assuming that, in a case where a viewer faces a side of a printing device from which a printed print medium is discharged, a direction from the right side of the printing device toward the left side is an X direction, a direction from a distal side (rear side) of the printing device to a proximal side (front side) is a Y direction, and a direction from a lower side of the printing device toward an upper side is a Z direction. As described above, the X direction, the Y direction, and the Z direction are each a direction from one side toward another side, and are directions orthogonal to each other. In the present specification, as necessary, each direction is described by appending “+ (plus)” in a case where the direction is from one side toward another side, and by appending “- (minus)” in a case where the direction is from another side toward one side.

[0037] In Figure 1 the printing device 10 illustrated, a printing unit 30 (see Figure 2A ) configured to perform printing by ejecting ink toward a conveyed print medium M from a print head 12 (see Figure 2A ) is housed in a housing 14 (see Figure 1 ). The printing device 10 includes, on a front side, an operation unit 16 configured to display various information and receive an operation by a user, a notification unit 18 configured to make a notification by audio, and a discharge unit 20 from which a printed print medium M is discharged. Further, the printing device 10 includes, on a rear side, a roll holding unit 22 holding a roll formed by winding a sheet-shaped print medium M, and capable of unwinding the roll and feeding the print medium M to the printing unit 30. Further, the printing device 10 includes a sheet feeding unit 24 capable of feeding a cut sheet-shaped print medium M having a predetermined size to the printing unit 30. Further, the printing device 10 includes an ink reservoir 26 configured to store ink to be supplied to the print head 12, and a housing unit 28 housing a waste liquid container (not illustrated) configured to store waste ink.

[0038] The printing device 10 includes a conveying mechanism (not illustrated) in the printing section 30 provided in the housing 14, which conveys the print medium M fed from the roll holding section 22 or the sheet feed section 24 to a position where the printing head 12 can perform printing, and discharges the print medium M subjected to printing from the discharge section 20. As the conveying mechanism, various known technologies such as a structure in which the print medium M is gripped by a driving roller and a driven roller configured to be in pressure contact with the driving roller and follow the driving roller, and the gripped print medium M is conveyed by driving of the driving roller, can be used. In the present embodiment, the print medium M is conveyed in the +Y direction.

[0039] The printing section 30 includes a carriage 32 in which the printing head 12 is mounted and which can be reciprocally moved in the X direction (see Figure 2A ). The carriage 32 is provided so as to be slidable on a guide rail (not illustrated) extending in the X direction, and is configured to be movable from one side to the other side (+X direction) and from the other side to the one side (-X direction) in the X direction by driving of a carriage motor 410 (see Figure 4 ). Thus, in the printing device 10, the printing head 12 mounted in the carriage 32 can also be reciprocally moved in the X direction via the carriage 32.

[0040] The printing section 30 includes a platen 34 configured to support the conveyed print medium M at a position facing the printing head 12 moved via the carriage 32. In the present embodiment, the platen 34 functions as a support section configured to support the conveyed print medium M. The printing section 30 has a structure in which the printing head 12 ejects ink while moving in the width direction of the print medium M (±X direction) via the carriage 32 with respect to the print medium M conveyed and supported on the platen 34 in the +Y direction. In the present embodiment, the platen 34 has a characteristic of absorbing light emitted thereto and not reflecting or hardly reflecting light emitted thereto. Note that a nozzle array 12a formed by arranging a plurality of nozzles configured to eject ink is formed on a surface of the printing head 12 facing the platen 34. The nozzle array 12a extends in the Y direction intersecting (orthogonal to, in the present embodiment) the moving direction (X direction) of the printing head 12.

[0041] The printing device 10 performs a printing operation in which ink is ejected to the print medium M conveyed to a printing start position by the conveying mechanism based on print data while moving the printing head 12 in the X direction (scanning), to perform printing. Next, the conveying mechanism conveys the print medium M by a predetermined amount, and the printing operation is performed again. As described above, the printing device 10 performs printing based on print data on the print medium M by repeatedly alternately performing the printing operation and the conveying operation.

[0042] The printing section 30 includes a first sensor 36 and a second sensor 38 capable of detecting an end portion of the print medium M in the X direction. The first sensor 36 and the second sensor 38 are provided in the carriage 32 and thereby configured to be reciprocally movable in the X direction via the carriage 32. The first sensor 36 is provided at one side (right side) of the carriage 32 in the X direction. On the other hand, the second sensor 38 is provided at the other side (left side) of the carriage 32 in the X direction. Note that, in the printing device 10, it is assumed that the print head 12 (carriage 32) is located at a standby position provided at one side in the X direction without performing printing. This standby position is provided at a position outside a printing region in which the print head 12 performs printing by ejecting ink to the print medium M. As will be described later in detail, the first sensor 36 and the second sensor 38 are optical sensors. In the present embodiment, the first sensor 36 and the second sensor 38 function as detection sections capable of detecting an end portion of the print medium M in the X direction.

[0043] <First sensor and second sensor>

[0044] Next, the structure of the first sensor 36 and the second sensor 38 will be described. Figure 3A and Figure 3B is a schematic configuration view of the first sensor 36 and the second sensor 38, Figure 3A is the first sensor 36, and Figure 3B is the second sensor 38.

[0045] The first sensor 36 includes a light emitting section 302 capable of emitting light to the platen 34 and the print medium M supported on the platen 34, and a light receiving section 304 capable of receiving reflected light from the platen 34 and the print medium M (see FIG. 6). Figure 3A Although the light emitting section 302 is arranged at one side (rear side) of the light receiving section 304 in the Y direction in the present embodiment, the arrangement is not limited thereto. For example, the light emitting section 302 can be arranged at the other side (front side) of the light receiving section 304 in the Y direction, or one side or the other side of the light receiving section 304 in the X direction.

[0046] The second sensor 38 includes a light emitting section 312 capable of emitting light to the platen 34 and the print medium M supported on the platen 34, and a light receiving member 314 capable of receiving reflected light from the platen 34 and the print medium M (see FIG. 7). Figure 3B Although the light emitting section 312 is arranged at the other side in the Y direction of the light receiving member 314 in the present embodiment, the arrangement is not limited thereto. For example, the light emitting section 312 can be arranged at one side in the Y direction of the light receiving member 314, or one side or the other side of the light receiving member 314 in the X direction.

[0047] The light-receiving member 314 includes a light-receiving element section 320, in which a plurality of light-receiving elements are arranged in a matrix in the X and Y directions. Specifically, in the light-receiving element section 320, a predetermined number of light-receiving elements arranged side by side in the Y direction are arranged in an array of multiple light-receiving elements in the X direction. Note that in this specification, the light-receiving element section 320 is illustrated as including... Figure 3B In the various figures, the example of the light-receiving element located in the middle in the Y direction is omitted. Furthermore, in the light-receiving member 314, three light-receiving portions are formed in the light-receiving element section 320. Specifically, one or more light-receiving element arrays located on the other side of the light-receiving element section 320 in the X direction form a first light-receiving portion 322. Furthermore, one or more light-receiving element arrays located on one side of the light-receiving element section 320 in the X direction form a second light-receiving portion 324. Note that in this embodiment, the first light-receiving portion 322 and the second light-receiving portion 324 overlap each other in the Y direction and are arranged to be spaced apart from each other in the X direction. Furthermore, one or more light-receiving element arrays located between the first light-receiving portion 322 and the second light-receiving portion 324 in the light-receiving element section 320 and not used in the first light-receiving portion 322 and the second light-receiving portion 324 form a third light-receiving portion 326. Note that the light-receiving element arrays to be used in each light-receiving portion can be fixed, or can be configured to be increased or decreased.

[0048] The outputs from each light-receiving unit in the light-receiving component 314 are input to the output switching amplifier 330. The output switching amplifier 330 allows switching of the output method. Specifically, the output switching amplifier 330 is configured such that the main controller 400 can switch between a differential mode based on the output values ​​of the first light-receiving unit 322 and the second light-receiving unit 324, and a single mode based on the output value of the third light-receiving unit 326. In the differential mode, the outputs from the first light-receiving unit 322 and the second light-receiving unit 324 are input to the differential amplifier 332 provided in the output switching amplifier 330. In the single mode, the output from the third light-receiving unit 326 is input to the single amplifier 334 provided in the output switching amplifier 330.

[0049] <Structure of the Control System for Printing Equipment>

[0050] Next, the structure of the control system of the printing device 10 will be explained. Figure 4 This is a block diagram illustrating the structure of the control system of the printing device 10.

[0051] The printing device 10 includes a main controller 400 configured to control the operation of the entire printing device 10. The main controller 400 executes various processes based on programs and data held in a flash ROM 402 and a RAM 404. The flash ROM 402 is a nonvolatile storage section, and stores programs, parameters, and correction data, and the like to be used in various processes. The RAM 404 is a volatile storage section, and temporarily holds programs and data, and the like.

[0052] The main controller 400 controls the ejection of ink from the print head 12 via a head driver 406. Further, the main controller 400 controls the driving of various motors via a motor driver 408. The motors whose driving is controlled by the motor driver 408 include a carriage (CR) motor 410 for moving the carriage 32 in the X direction, and a paper feed (LF) motor 412 for driving a drive roller (not illustrated) configured to convey the print medium M. In addition to these motors, although illustration is omitted, a motor configured to drive a maintenance section (not illustrated) for maintaining and restoring the ejection performance of ink from the nozzles in the print head 12, and the like are also controlled via the motor driver 408. The main controller 400 detects the driving amount of each motor by using an encoder sensor 414 corresponding to each motor, and controls the driving of the motor. The encoder scale read by the encoder sensor 414 is a linear scale and a rotary scale. In both types of scales, the driving amount is detected based on the count of the sensor.

[0053] Further, the main controller 400 is connected to the first sensor 36 and the second sensor 38. In the first sensor 36, the driving of the light emitting section 302 is controlled by the main controller 400. Further, in the light receiving section 304 of the first sensor 36, the signal based on the light receiving amount is amplified to a level suitable for the main controller 400, and is obtained by a sensor input 416 of the main controller 400 as an analog input level. In the second sensor 38, the driving of the light emitting section 312 is controlled by the main controller 400. Further, in each of the light receiving sections in the light receiving member 314 of the second sensor 38, the signal based on the light receiving amount is converted in the differential amplifier 332 (see Figure 3B ) or the single amplifier 334 of the output switching amplifier 330, and then amplified to a level suitable for the main controller 400. In the main controller 400, the sensor input 416 obtains the amplified signal as an analog input level. The printing device 10 is configured so that the gain of the differential amplifier 332 can be changed from the main controller 400, thereby analogically adapting to the light receiving signal level. The main controller 400 obtains the position coordinates of the positions detected by the first sensor 36 and the second sensor 38 in a position coordinate obtaining section 418 based on the signals obtained from the first sensor 36 and the second sensor 38, and calculates each end portion of the print medium M in the X direction in a calculation section 420.

[0054] <Detection operation using the first sensor and the second sensor>

[0055] The print medium M is generally white, and in the present embodiment, the platen 34 has a light-absorbing property (that is, black). Therefore, the light emitted from each light emitting portion is almost completely reflected on the print medium M, and almost completely absorbed on the platen 34. Thus, a difference in the amount of light received in the light receiving portion occurs between the print medium M and the platen 34. The first sensor 36 and the second sensor 38 detect each end portion of the print medium M based on this difference in the amount of light received in the light receiving portion that occurs between the print medium M and the platen 34.

[0056] Detection operation using the first sensor 36

[0057] First, an outline of the detection operation using the first sensor 36 will be described. Figures 5A-5C is a graph illustrating a change in the output of the first sensor 36 in three different states. Figure 6 is a graph illustrating an example of the output waveform of the first sensor 36. Note that, in Figures 5A-5C , the light emitting portion 302 is arranged at a position separated from the light receiving portion 304 in the X direction for ease of understanding.

[0058] Figures 5A-5C A case is illustrated in which the first sensor 36 moves from the other side toward the one side (-X direction) with respect to the print medium M above the print medium M supported on the platen 34, and this situation changes sequentially from Figure 5A illustrated state to Figure 5B illustrated state, and then to Figure 5C illustrated state. The light receiving portion 304 receives reflected light from within the spot diameter Sd of the light receiving portion 304, and outputs a voltage corresponding to the amount of light by converting the received light into a voltage. The light emitting portion 302 emits light to the entire region within the spot diameter Sd of the light receiving portion 304.

[0059] In a case where the print medium M is located in the entire region of the spot diameter Sd, the amount of light received in the light receiving portion 304 is maximized due to the reflected light from the print medium M located in the spot diameter Sd, and the output voltage of the light receiving portion 304 takes a maximum value (see Figure 5A ).

[0060] In a case where the print medium M is located in the entire region of the spot diameter Sd, the amount of light received in the light receiving portion 304 is maximized due to the reflected light from the print medium M located in the spot diameter Sd, and the output voltage of the light receiving portion 304 takes a maximum value (see Figure 5AWhen the first sensor 36 moves from one side to the other in the X direction and the platform 34 is located in the region within the light spot diameter Sd, as the proportion of the area occupied by the platform 34 in this region increases, the amount of light reflected from the light spot diameter Sd decreases. Therefore, the amount of light received in the light-receiving section 304 decreases in response to the movement of the first sensor 36, and the output voltage of the light-receiving section 304 gradually decreases (see...). Figure 5B ).

[0061] Then, from Figure 5B When the first sensor 36 moves further from one side to the other in the X direction and is not positioned on the printing medium M (that is, only the stage 34 is located in the entire area within the spot diameter Sd), almost no light is reflected from within the spot diameter Sd. Therefore, the output voltage of the light-receiving part 304 is at its minimum (see...). Figure 5C ).

[0062] The output waveform based on the aforementioned output voltage change is as follows: Figure 6 As illustrated, in the portion near the end of the printing medium M where the proportion of the area occupied by the printing medium M in the spot diameter Sd changes, the output waveform changes, and the value of the output voltage decreases in response to the decrease in proportion. Therefore, based on this change in the output waveform, the output voltage at the position corresponding to the end position of the printing medium M is set as a threshold, and the position of the end of the printing medium M is calculated based on the coordinates when the output voltage passes through this threshold. For example, this threshold can be determined experimentally depending on the type of printing medium M to be used.

[0063] Detection operation using the second sensor 38

[0064] Next, an overview of the detection operation using the second sensor 38 will be described. Note that the second sensor 38 is configured such that its mode can be selected between a differential mode using the first light-receiving unit 322 and the second light-receiving unit 324, and a single mode using the third light-receiving unit 326. Specifically, when the differential mode is set, the second sensor 38 detects each end of the printing medium M in the X direction using the first light-receiving unit 322 and the second light-receiving unit 324, and when the single mode is set, it detects the end using the third light-receiving unit 326.

[0065] Detection operations in differential mode

[0066] First, let's outline the detection operations in differential mode. Figure 7 This diagram illustrates the light emission from the light-emitting part 312 in the second sensor 38 and the light reception in the first light-receiving part 322 and the second light-receiving part 324. Figures 8A-8Cis a graph illustrating changes in the outputs from the first light-receiving section 322 and the second light-receiving section 324 in the three different states. Figure 9 is a graph illustrating output waveforms of the first light-receiving section 322 and the second light-receiving section 324 and an output waveform of the differential amplifier 332 in a case where the relative positional relationship between the second sensor and the print medium M supported on the platen 34 changes in the X direction. Note that, in Figures 7-9 , the light-emitting section 312 is arranged at a position separated from the light-receiving member 314 in the X direction for ease of understanding.

[0067] In the differential mode, the first light-receiving section 322 receives reflected light in the light-receiving region La1 from which the first light-receiving section 322 can receive light, and outputs a voltage corresponding to the amount of light by converting the received light into a voltage. Further, in the differential mode, the second light-receiving section 324 receives reflected light in the light-receiving region La2 from which the second light-receiving section 324 can receive light, and outputs a voltage corresponding to the amount of light by converting the received light into a voltage. Note that the light-receiving regions La1 and La2 do not overlap each other in the X direction and have the same area. Note that having the same area is not limited to having exactly the same area, and also includes a case where the difference between the areas of the two light-receiving regions La1 and La2 is within a predetermined range.

[0068] In the differential mode, the output voltages from the first light-receiving section 322 and the second light-receiving section 324 are input into the differential amplifier 332. In the differential amplifier 332, the difference between the voltage value VA output from the first light-receiving section 322 and the voltage value VB output from the second light-receiving section 324 is amplified, and a differential signal Vout is output. The light-emitting section 312 emits light to the entire region in the light-receiving region La1 of the first light-receiving section 322 and the entire region in the light-receiving region La2 of the second light-receiving section 324.

[0069] Reference is made to Figures 8A-8C , the changes in the output waveforms of the first light-receiving section 322 and the second light-receiving section 324 in the differential mode are explained with a focus on one of these light-receiving sections. Figures 8A-8C A case is illustrated in which the second sensor 38 moves relative to the print medium M from the other side in the X direction toward the one side (-X direction) above the print medium M supported on the platen 34, and this situation changes sequentially from Figure 8A the illustrated state to Figure 8B the illustrated state, and then to Figure 8C the illustrated state. In a case where the print medium M is located in the entire region of the light-receiving region La, the amount of light received in the light-receiving section is maximized by reflected light from the print medium M located in the light-receiving region La, and the output voltage of the light-receiving section is maximized (see Figure 8A ).

[0070] In a state where the second sensor 38 moves from the other side toward the one side in the X direction and the platen 34 is positioned in a region within the light-receiving region La, as the proportion of the area occupied by the platen 34 in the region increases, the amount of light reflected from the light-receiving region La decreases. Therefore, the amount of light received in the light-receiving portion decreases in response to the movement of the second sensor 38, and the output voltage of the light-receiving portion gradually decreases (see Figure 8A ). Figure 8B

[0071] Then, in a state where the second sensor 38 further moves from the other side toward the one side in the X direction from the state in Figure 8B , and the platen 34 is positioned in the entire region within the light-receiving region La (that is, the print medium M is not positioned, and only the platen 34 is positioned in the entire region within the light-receiving region La), almost no light is reflected from within the light-receiving region La. Therefore, the output voltage of the light-receiving portion takes a minimum value (see Figure 8C ).

[0072] In the second sensor 38, the output voltage changes as described above in the first light-receiving portion 322 and the second light-receiving portion 324. Note that, since the first light-receiving portion 322 and the second light-receiving portion 324 are provided at different positions in the X direction, the positions at which the output voltage changes (the output waveform tilts) are displaced from each other in the X direction. Then, the output voltages of the first light-receiving portion 322 and the second light-receiving portion 324 are input into the differential amplifier 332. In the differential amplifier 332, a differential signal Vout is output based on the difference between the output voltage of the first light-receiving portion 322 and the output voltage of the second light-receiving portion 324. Therefore, in the output waveform illustrating the change in the differential signal Vout, a waveform having a predetermined shape is formed in a region in which there is a difference between the output voltage of the first light-receiving portion 322 and the output voltage of the second light-receiving portion 324 (that is, in the vicinity of the end portion of the print medium M). The output waveform of the differential amplifier 332 is described below with reference to Figure 9 .

[0073] It is assumed that the second sensor 38 is at a first position at which the print medium M is positioned in the entire region of each of the light-receiving region La1 of the first light-receiving portion 322 and the light-receiving region La2 of the second light-receiving portion 324. In this case, both the output voltage VA of the first light-receiving portion 322 and the output voltage VB of the second light-receiving portion 324 take a maximum value and are the same value. Therefore, at the first position, the difference between the output voltage VA and the output voltage VB is 0 V, and the differential signal Vout from the differential amplifier 332 is 0 V. Note that, in Figure 9 , the portions in which the output voltages are the same in the output waveform of the output voltage VA and the output waveform of the output voltage VB are illustrated by providing a gap between the output waveforms for ease of understanding. ​

[0074] When the second sensor 38 moves from the first position to the other side in the X direction, it transitions to a second position. In this second position, the printing medium M is located within the entire light-receiving area La1 of the first light-receiving section 322, and the stage 34 is located within a portion of the light-receiving area La2 of the second light-receiving section 324. At this second position, a difference exists between the output voltage VA of the first light-receiving section 322 and the output voltage VB of the second light-receiving section 324. Specifically, the output voltage VA of the first light-receiving section 322 is higher than the output voltage VB of the second light-receiving section 324. More specifically, the output voltage VA of the first light-receiving section 322 remains at its maximum value, while the output voltage VB of the second light-receiving section 324 gradually decreases with movement. Therefore, at the second position, the difference between the output voltage VA and the output voltage VB gradually increases with movement, and the differential signal Vout increases accordingly.

[0075] Furthermore, as the second sensor 38 moves further from the second position to the other side in the X direction, it transitions to a third position. In the third position, the printing medium M is located within the entire light-receiving area La1 of the first light-receiving section 322, and the stage 34 is located within the entire light-receiving area La2 of the second light-receiving section 324. In the third position, the output voltage VA of the first light-receiving section 322 remains at its maximum value, while the output voltage VB of the second light-receiving section 324 reaches and remains at its minimum value. Therefore, the difference between the output voltages VA and VB is maximized, and the differential signal Vout reaches its maximum value.

[0076] Then, as the second sensor 38 moves further from the third position towards one side in the X direction, the second sensor 38 transitions to the fourth position. In the fourth position, the stage 34 is located within a portion of the light-receiving area La1 of the first light-receiving section 322, and the stage 34 is located within the entire area of ​​the light-receiving area La2 of the second light-receiving section 324. In the fourth position, the output voltage VA of the first light-receiving section 322 gradually decreases with the movement, while the output voltage VB of the second light-receiving section 324 remains at its minimum value. Therefore, in the fourth position, the difference between the output voltage VA and the output voltage VB gradually decreases with the movement, and the differential signal Vout decreases accordingly.

[0077] Then, in a case where the second sensor 38 further moves from the fourth position from the other side toward the one side in the X direction, the second sensor 38 transitions to a fifth position. At the fifth position, the platen 34 is positioned in the entire region of each of the light-receiving regions La1 and La2 of the first and second light-receiving portions 322 and 324. At the fifth position, the output voltage VA of the first light-receiving portion 322 and the output voltage VB of the second light-receiving portion 324 both take a minimum value and are the same value. Therefore, at the fifth position, the difference between the output voltage VA and the output voltage VB is 0 V, and the differential signal Vout from the differential amplifier 332 is 0 V.

[0078] In response to this change in the output Vout of the differential amplifier 332, the position P1 at which the output Vout exceeds the first threshold value Th1 set in advance and the position P2 at which the output Vout falls below the first threshold value Th1 are detected, and the midpoint P0 of the positions P1 and P2 is obtained as the end position of the print medium M. Note that, for example, the first threshold value Th1 described above is determined through experiments in accordance with the type of print medium M to be used, or the like.

[0079] • Detection operation in single mode

[0080] Next, an outline of the detection operation in the single mode will be described. Figure 10 is a view illustrating output waveforms corresponding to changes in the output voltage VC of the third light-receiving portion 326 and output waveforms corresponding to changes in the output signal Vout of the single amplifier 334 in a case where the relative positional relationship between the second sensor and the print medium M supported on the platen 34 changes in the X direction. Note that, in Figure 10 In FIG. 10, the light-emitting portion 312 is omitted for ease of understanding.

[0081] In the single mode, the third light-receiving portion 326 receives reflected light in the light-receiving region La3 from which the third light-receiving portion 326 can receive light, and outputs a voltage corresponding to the amount of light by converting the received light into a voltage. The output voltage from the third light-receiving portion 326 is input into the single amplifier 334, amplified and inverted therein, and output. The light-emitting portion 312 emits light to the entire region within the light-receiving region La3 of the third light-receiving portion 326.

[0082] Reference Figure 10 The changes in the output waveforms of the third light-receiving portion 326 and the changes in the output waveforms of the single amplifier 334 in the single mode will be described. Figure 10 is a view illustrating a case where the second sensor 38 moves relative to the print medium M above the print medium M supported on the platen 34 from the other side in the X direction toward the one side (-X direction).

[0083] Assuming that the second sensor 38 is in the sixth position at which the print medium M is located in the entire region of the light-receiving region La3 of the third light-receiving section 326. In this case, the output voltage VC of the third light-receiving section 326 takes a maximum value, and the output signal Vout based on the output voltage VC takes a minimum value.

[0084] In a case where the second sensor 38 moves from the sixth position from the other side toward the one side in the X direction, the second sensor 38 transitions to a seventh position at which the platen 34 is located in a part of the light-receiving region La3 of the third light-receiving section 326. At the seventh position, the amount of light reception in the third light-receiving section 326 decreases in accordance with the proportion of the light-receiving region La3 occupied by the platen 34. Therefore, at the seventh position, the output voltage VC of the third light-receiving section 326 gradually decreases with movement. The output signal Vout is thereby gradually increased in response to the change in the output voltage VC.

[0085] Then, in a case where the second sensor 38 further moves from the seventh position from the other side toward the one side in the X direction, the second sensor 38 transitions to an eighth position at which the platen 34 is located in the entire region of the light-receiving region La3 of the third light-receiving section 326. At the eighth position, almost no light is reflected from the light-receiving region La3, and the amount of light reception in the third light-receiving section 326 is minimized. Therefore, at the eighth position, the output voltage VC of the third light-receiving section 326 takes a minimum value, and the output signal Vout based on the output voltage VC takes a maximum value.

[0086] Then, based on the output voltage VC of the third light-receiving section 326, the output signal Vout of the single amplifier 334 is detected to pass through a position P3 of a second threshold value Th2 set in advance with respect to the change in the output signal Vout, and the position P3 is obtained as the end position of the print medium M. Note that, for example, the second threshold value Th2 as described above is determined through experiments in accordance with the type of the print medium M to be used, or the like.

[0087] <Print processing>

[0088] In the above-described structure, the printing device 10 performs print processing of printing the print medium M based on a print job. Figure 11 is a flowchart illustrating details of the print processing. Figure 12 (A) to (L) of FIG. 12 are diagrams illustrating positions of the first sensor 36 and the second sensor 38 with respect to the print medium M at respective timings in the print processing. The main controller 400 performs a series of processes illustrated in the flowchart of Figure 11 of FIG. 12 by expanding and executing program codes stored in the flash ROM 402 on the RAM 404. Alternatively, Figure 11A part or all of the functions of the steps in the flowchart can be executed by hardware such as an ASIC or an electronic circuit. In the present specification, the symbol S in the description of each process in the flowchart means the step in the flowchart.

[0089] In the following description, a case where the printing device 10 performs bidirectional printing in a forward direction (+X direction) from one side to the other side in the X direction and a backward direction (-X direction) from the other side to the one side in the X direction is described as an example. Further, the printing device 10 repeatedly performs the scan relating to printing by the print head 12 a plurality of times to print an image based on print data on the print medium M. In the present embodiment, the main controller 400 functions as a print control section configured to control bidirectional printing by the printing section 30 in the forward direction and the backward direction.

[0090] In a case where the printing processing is started, first, in S1102, the main controller 400 sets a variable n indicating the number of times of the scan relating to printing by the print head 12 to "1". Next, in S1104, the main controller 400 performs the nth scan relating to printing. Specifically, in a case where the variable n is 1, the print head 12 in the standby position (see (A) of FIG. 10) performs printing by ejecting ink to the print medium M while moving in the forward direction (see (B) of FIG. 10). Further, in a case where the variable n is an even number, the print head 12 in the stop position on the other side in the X direction (see (F) of FIG. 10) performs printing by ejecting ink to the print medium M while moving in the backward direction (see (G) of FIG. 10). Further, in a case where the variable n is an odd number other than 1, the print head 12 in the stop position at the one side in the X direction (see (K) of FIG. 10) performs printing by ejecting ink to the print medium M while moving in the forward direction (see (L) of FIG. 10). Figure 12 Figure 12 Figure 12 Figure 12 Figure 12 Figure 12

[0091] ​​​​​​The print start position in the X direction at the time of the scan involving printing is the position set in S1110 at the time of the scan via and immediately after the execution of S1108 to S1110 to be described later, and is the position set in S1118 at the time of the scan via and immediately after the execution of S1116 to S1118 to be described later. Note that in the case where the variable n is "1" (that is, in the first scan involving printing), the position set in advance can be set as the print start position in the X direction. Alternatively, the configuration can be such that the scan of the carriage 32 is performed before the first scan involving printing, so that the first sensor 36 or the second sensor 38 detects the position of the end ER on one side of the print medium M, and the print start position in the X direction at the time of the first scan involving printing is set based on the detection result.

[0092] In the case where the n-th scan involving printing is started, in S1106, the main controller 400 determines whether the variable n is odd. In this case, in the printing device 10, the print head 12 is moved in the advancing direction from one side toward the other side in the X direction in the odd-numbered scan involving printing, and is moved in the retreating direction from the other side toward one side in the X direction in the even-numbered scan involving printing.

[0093] Therefore, in the odd-numbered scan involving printing in which the print head 12 is moved in the advancing direction, the second sensor 38 can detect the end EL on the other side in the X direction of the print medium M before the first sensor 36 (see (C) of FIG. 10). Further, in the odd-numbered scan involving printing, the distance of movement of the print head 12 in the advancing direction can be reduced from the distance of movement of the print head 12 in the advancing direction in the case where the first sensor 36 is used by detecting the end EL using the second sensor 38 (see (D) of FIG. 10). Figure 12 Figure 12

[0094] On the other hand, in the even-numbered scan involving printing in which the print head 12 is moved in the retreating direction, the first sensor 36 can detect the end ER on one side in the X direction of the print medium before the second sensor 38 (see (H) of FIG. 11). Further, in the even-numbered scan involving printing, the distance of movement of the print head 12 in the retreating direction can be reduced from the distance of movement of the print head 12 in the retreating direction in the case where the second sensor 38 is used by detecting the end ER using the first sensor 36 (see (I) of FIG. 11). Figure 12 Figure 12

[0095] ​​​​If it is judged in S1106 that the variable n is odd, the processing proceeds to S1108, and the main controller 400 judges whether or not the end portion EL on the other side of the print medium M is detected with the second sensor 38. The detection of the end portion position of the print medium M with the second sensor 38 is performed based on the setting of the differential mode or the single mode. In the case of the differential mode, the coordinates of two points through which the differential signal Vout of the differential amplifier 332 passes as moving in the scanning direction through the first threshold Thl are obtained, and the midpoint P0 between the two points is detected as the end portion position of the print medium M. In the case of the single mode, the point through which the output signal Vout of the single amplifier 334 passes as moving in the scanning direction through the second threshold Th2 is detected as the end portion position of the print medium M. As described above, in the present embodiment, the main controller 400 (the position coordinate obtaining section 418 and the calculating section 420) functions as an obtaining section configured to detect the end portion of the print medium M in the X direction and obtain the position of the end portion.

[0096] If it is judged in S1108 that the end portion EL of the print medium M is detected with the second sensor 38 (see Figure 12 (C)), the processing proceeds to S1110, and the main controller 400 sets the position of the detected end portion EL as the print start position in the X direction at the time of the next scanning involving printing. As described above, in the present embodiment, the main controller 400 functions as a determining section configured to determine the print start position at the time of the next scanning involving printing.

[0097] In the case where the n-th scanning involving printing is completed, the carriage 32 is stopped at a downstream stop position in the moving direction of the scanning (see Figure 12 (D) and Figure 12 (I) of FIG. 4). Thereafter, the printing device 10 conveys the print medium M by a predetermined amount with the conveying mechanism (see Figure 12 (E) and Figure 13 (J) of FIG. 4), and stands by until the execution of the next scanning involving printing.

[0098] Then, in S1112, the main controller 400 judges whether or not the printing based on the print job is completed. If it is judged in S1112 that the printing based on the print job is completed, the printing processing is terminated. On the other hand, in the case where it is judged in S1112 that the printing based on the print job is not completed, the processing proceeds to S1114, the main controller 400 increments the variable n, and the processing returns to S1104.

[0099] Further, if the main controller 400 determines in S1106 that the variable n is even, the processing proceeds to S1116, and the main controller 400 determines whether the end portion ER on one side of the print medium M is detected with the first sensor 36. In the first sensor 36, the output voltage of the light-receiving portion 304 in the first sensor 36 is detected as the end portion position of the print medium M as the point at which the output voltage passes through the threshold with movement in the scanning direction. If the main controller 400 determines in S1116 that the end portion ER of the print medium M is detected with the first sensor 36 (see FIG. 11B), the processing proceeds to S1118. In S1118, the main controller 400 sets the position of the detected end portion ER as the print start position in the X direction at the next scan involving printing, and the processing proceeds to S1112. Figure 14

[0100]

[0101] Note that, although the above describes a case of bidirectional printing in which the printing device 10 performs printing while moving in the advancing direction and the retreating direction in the X direction in the print processing, the technology of the present disclosure is not limited to a printing device that performs bidirectional printing. The technology according to the present disclosure can also be applied to a printing device that performs unidirectional printing in which printing is performed while moving in the advancing direction or the retreating direction in the X direction.

[0102] In this case, for example, in a form in which printing is performed while the print head 12 moves in the advancing direction, the position of the end portion ER on one side of the print medium M corresponds to the print start position. Therefore, in a case where the scan involving printing is completed and the print head 12 moves to the start position for starting the next scan involving printing, the processing of S1116 and S1118 is performed. Further, for example, in a form in which printing is performed while the print head 12 moves in the retreating direction, the position of the end portion EL on the other side of the print medium M corresponds to the print start position. Therefore, in a case where the scan involving printing is completed and the print head 12 moves to the start position for starting the next scan involving printing, the processing of S1108 and S1110 is performed.

[0103] Although in the above description, the sensor for detecting the end portion position of the print medium M is determined based on the number of scans involving printing with the print head 12 in the print processing, the present disclosure is not limited thereto. For example, the sensor for detecting the end portion position can be determined based on the direction in which the scan with the print head 12 is performed. Specifically, in a case where the print head 12 moves in the advancing direction, the second sensor 38 detects the end portion EL of the print medium M, and in a case where the print head 12 moves in the retreating direction, the first sensor 36 detects the end portion ER of the print medium M.

[0104] ​​In the above description, the second sensor 38 is used to detect the end portion EL of the print medium M on the other side in the X direction. Although not particularly described in the above description, the present disclosure is not limited thereto. For example, the second sensor 38 can be used to detect the end portion ER of the print medium M on the one side in the X direction, to detect the passage of the print medium on the platen, and to detect the leading edge portion of the print medium M in the conveyance direction, and the like. Further, although the first sensor 36 is used to detect the end portion ER of the print medium M on the one side in the X direction, the present disclosure is not limited thereto. For example, the first sensor 36 can be used for operations such as registration adjustment for adjusting the drop position of the ejected ink droplets, and the like.

[0105] Although in the above description the first sensor 36 is provided on the one side of the carriage 32 in the X direction and the second sensor 38 is provided on the other side of the carriage 32 in the X direction, the present disclosure is not limited thereto. The configuration can be such that the first sensor 36 is provided on the other side of the carriage 32 in the X direction and the second sensor 38 is provided on the one side of the carriage 32 in the X direction. Further, the configuration can be such that the first sensor 36 is not provided and the second sensor 38 is provided on the one side and the other side of the carriage 32 in the X direction.

[0106] Although in the above description the second sensor 38 includes the third light receiving portion 326, the second sensor 38 can have a configuration that does not include the third light receiving portion 326. Further, the configuration of the position coordinate obtaining portion 418 and the calculation portion 420, and the like, which obtain the end portion position of the print medium M based on the output values from the output switching amplifier 330, the first sensor 36, and the second sensor 38, can be such that these portions are provided in an external device connected to the printing device 10. Further, although in the above description the end portion EL is detected by using the second sensor 38 in S1108 and the end portion ER is detected by using the first sensor 36 in S1116, the present disclosure is not limited thereto. The differential mode of the second sensor 38 can be used to detect the end portion EL in S1108 and to detect the end portion ER in S1116.

[0107] <Operation and Effect>

[0108] As described above, the printing device 10 according to the present embodiment includes the first sensor 36 on the one side in the moving direction of the carriage 32 on which the print head 12 is mounted, and the second sensor 38 is provided on the other side in the moving direction. Further, the first sensor 36 or the second sensor 38 obtains the end portion position of the print medium M in a scan that involves printing with the print head 12. Then, based on the obtained end portion position, the printing start position in the moving direction of the scan at the next scan that involves printing is determined.

[0109] This reduces the scan range of the print head 12 (the carriage 32) at the time of printing scanning, and can contribute to the downsizing of the printing device 10 and the shortening of the period required for the printing process. Furthermore, in the scan involving printing, the printing start position at the time of the next scan involving printing is obtained. Thus, it is less likely that a margin is formed in the case where marginless printing is performed, and for example, printing can be performed very close to the end portions EL and ER of the printing medium M in the scan direction. Thus, micro-margin printing in which a very small margin is formed in the end portions EL and ER can be performed, and a visual effect equivalent to marginless printing can be obtained. In this case, it is not necessary to fit, for example, an absorber or the like in the platen 34, and the structure around the platen 34 can be simplified.

[0110] (Second Embodiment)

[0111] Next, a printing device according to a second embodiment will be described with reference to Figure 13 and Figure 13 In the following description, structures that are the same as or correspond to the structures of the above-described printing device according to the first embodiment are denoted by the same reference numerals as those used in the first embodiment, and detailed description thereof is omitted.

[0112] As described above, the printing device is configured such that, in the differential mode, the second sensor 38 receives reflected light of the light emitted from the light emitting portion 312 in the first light receiving portion 322 and the second light receiving portion 324, and outputs a voltage corresponding to the amount of light received. Thus, in the output waveform of the differential amplifier 332, a pulse having a very small width is sometimes formed due to fluctuations or noise in the sensor signal. In the case where such a pulse has an intensity exceeding the first threshold value Th1, four or more points at which the output voltage passes the first threshold value Th1 are formed, and there is a possibility that the end portion of the printing medium M in the X direction cannot be accurately detected.

[0113] In the second embodiment, in the case where a pulse formed by fluctuations or noise or the like in the sensor signal described above is generated with an intensity exceeding the first threshold value Th1, the end portion position of the printing medium in the X direction can also be accurately obtained. Specifically, the two coordinates of the coordinate pair in which the output voltage has passed the first threshold value Th1 in the rising and falling of the output waveform are set to true values in the case where the distance between the two coordinates of the coordinate pair is closest to the theoretical value, and these true values are used to obtain the end portion position of the printing medium in the X direction.

[0114] <Outline of Obtaining the End Portion Position of the Printing Medium>

[0115] First, an outline of obtaining the end portion position of the printing medium in the X direction in the printing device 10 according to the present embodiment will be described. Figure 13This is a schematic diagram illustrating the position of the end of the printing medium obtained in the printing apparatus 10 according to this embodiment. Note that in Figure 14 In this configuration, the light-emitting portion 312 is positioned separately from the light-receiving member 314 in the X direction for ease of understanding. Furthermore, Figure 14 An example is shown where a gap is set between the output waveforms of output voltage VA and output voltage VB in the same portion of the output voltage to facilitate understanding.

[0116] Assuming that the second sensor 38 moves from above the printing medium M, through one end ER of the printing medium M, and to a position above the stage 34, the output voltage VB is affected by noise N before the second light-receiving part 324 passes through the end ER, and decreases. In this case, in the output waveform of the output signal Vout based on the differential amplifier 332, a waveform Wa2 formed by the influence of noise N is formed near the waveform Wa1 formed near the end ER.

[0117] The position coordinate acquisition unit 418 acquires, for each of waveforms Wa1 and Wa2, a first coordinate when the output signal Vout exceeds a first threshold Th1 and a second coordinate when the output signal Vout drops below the first threshold Th1. Specifically, it acquires a first coordinate Pa and a second coordinate Pb for waveform Wa1, and a first coordinate Pc and a second coordinate Pd for waveform Wa2. Then, the position coordinate acquisition unit 418 acquires the distance L between the first and second coordinates, compares each distance L with a theoretical value T, and sets the first and second coordinates corresponding to the distance L closest to the theoretical value T as true values. Note that in this embodiment, the theoretical value T is the distance in the X direction between the center position of the first light-receiving part 322 and the center position of the second light-receiving part 324. Then, the calculation unit 420 acquires the midpoint P0 of the first and second coordinates set as true values ​​as the end ER of the printing medium M.

[0118] In this embodiment, since the distance L1 between the first coordinate Pa and the second coordinate Pb of waveform Wa1 is closer to the theoretical value T than the distance L2 between the first coordinate Pc and the second coordinate Pd of waveform Wa, the first coordinate Pa and the second coordinate Pb are set to true values. Then, the end point ER is obtained based on the first coordinate Pa and the second coordinate Pb set to true values. Note that the method for obtaining the end position of the printing medium M is not limited to this. For example, the first coordinate or the second coordinate set to true values ​​can be determined as the end position. Alternatively, the end position can be determined by adding an offset distance based on the theoretical value to the first coordinate or the second coordinate set to true values, or by subtracting the offset distance based on the theoretical value from the first coordinate or the second coordinate set to true values.

[0119] <Processing>

[0120] Next, the obtaining process of the end portion of the print medium M based on the differential signal Vout of the differential amplifier 332 in the differential mode will be described. Note that the obtaining process described below is started after the start of the scan related to printing in the nth time in S1104 in the above-described printing process, and is executed in S1108, for example. Figure 14 is a flowchart illustrating details of the obtaining process of the end portion of the print medium M based on the differential signal Vout. The main controller 400 performs the series of processes illustrated in the flowchart of Figures 15A-19 Alternatively, Figure 15A Part or all of the functions of the steps in

[0121] In the case where the obtaining process is started, first, in S1402, the main controller 400 determines whether the obtained differential signal Vout of the differential amplifier 332 has passed the first threshold Th1. Specifically, in the case where the scan related to printing with the print head 12 is started, the main controller 400 starts monitoring the differential signal Vout of the differential amplifier 332. Thus, in S1402, the main controller 400 determines whether the differential signal Vout has exceeded the first threshold Th1 in the case where the differential signal Vout is rising, and determines whether the differential signal Vout has fallen below the first threshold Th1 in the case where the differential signal Vout is falling. Specifically, if the main controller 400 determines that the differential signal Vout has exceeded the first threshold Th1 or has fallen below the first threshold Th1 in S1402, the main controller 400 determines that the differential signal Vout has passed the first threshold Th1. On the other hand, if the main controller 400 determines that the differential signal Vout has not exceeded the first threshold Th1 or has not fallen below the first threshold Th1, the main controller 400 determines that the differential signal Vout has not passed the first threshold Th1. Note that if the main controller 400 determines that the differential signal Vout has passed the first threshold Th1 in S1402, the main controller 400 obtains the coordinate value at the time of making the determination (that is, the coordinate value at the time when the differential signal Vout has reached the first threshold Th1).

[0122] If the main controller 400 determines in S1402 that the differential signal Vout has not passed the first threshold Thl, the process proceeds to S1410 to be described later. On the other hand, if the main controller 400 determines in S1402 that the differential signal Vout has passed the first threshold Thl, the process proceeds to S1404, and the main controller 400 determines whether the coordinate immediately obtained is the first coordinate. If the main controller 400 determines in S1404 that the coordinate immediately obtained is not the first coordinate, the process proceeds to S1406, and the main controller 400 holds the coordinate obtained in S1402 as the first coordinate, and proceeds to S1410. On the other hand, if the main controller 400 determines in S1404 that the coordinate immediately obtained is the first coordinate, the process proceeds to S1408, the main controller 400 holds the coordinate obtained in S1402 as the second coordinate, and the process proceeds to S1410. Note that, in S1408, the held second coordinate is associated with the first coordinate immediately obtained.

[0123] In S1410, the main controller 400 determines whether the carriage 32 has moved to a stop position. Note that the stop position is stored in advance in a storage area of the printing device 10. If the main controller 400 determines in S1410 that the carriage 32 has not moved to the stop position, the process returns to S1402. On the other hand, if the main controller 400 determines in S1410 that the carriage 32 has moved to the stop position, the process proceeds to S1412, and the main controller 400 obtains the true value of the coordinate.

[0124] In S1412, the distance between the two coordinates of the first coordinate and the second coordinate associated with each other is obtained, and the first coordinate and the second coordinate corresponding to the distance closest to the theoretical value T obtained are obtained as the true value of the coordinate. The theoretical value T is stored in advance in the storage area. Note that, in the case where only a pair of the first coordinate and the second coordinate associated with each other exists, these coordinates are obtained as the true value of the coordinate. Then, in S1414, the main controller 400 obtains the end portion of the print medium M on the basis of the first coordinate and the second coordinate set as the true value, and terminates the obtaining process. Specifically, in S1414, the midpoint P0 of the first coordinate and the second coordinate set as the true value is obtained as the end portion of the print medium M in the X direction.

[0125] <Modification Example>

[0126] In the above description, the obtained first coordinates and second coordinates are all held, and then the true values of the coordinates are obtained. However, the present disclosure is not limited to this. For example, the structure can be as follows. After the second coordinates are obtained, the distance between the first coordinates and the second coordinates associated with each other is obtained, and in a case where the difference between the obtained distance and the theoretical value T is greater than a predetermined value, the first coordinates and the second coordinates are judged as outliers and are not held in the storage region. Specifically, in this case, a midpoint between two points for which the above-described difference is equal to or less than the predetermined value is obtained as the end portion of the print medium M, and the midpoint is held in the storage region. Note that the predetermined value is, for example, 20% of the theoretical value T. This reduces the amount of use of the storage region in a case where the obtaining processing is performed.

[0127] <Operation and Effect>

[0128] As described above, in the present embodiment, the distance between the two coordinates of the obtained first coordinates and second coordinates is compared with the theoretical value based on the distance between the first light-receiving portion 322 and the second light-receiving portion 324. Then, the two coordinates corresponding to the distance close to the theoretical value are set as the true values of the first coordinates and the second coordinates, and the end portion of the print medium M is obtained by using these true values. Even in a case where fluctuations or noise occur in the output signal from the light-receiving portion, this structure can eliminate the waveform caused by fluctuations or noise in the output waveform of the differential signal Vout, and enables accurate detection of the end portion of the print medium M.

[0129] (Third Embodiment)

[0130] Next, reference will be made to Figure 15B The print apparatus according to the third embodiment will be described. In the following description, the structure same as or corresponding to the structure of the print apparatus according to the first embodiment described above is denoted by the same reference sign as used in the first embodiment, and detailed description thereof is omitted.

[0131] The first sensor 36 has a simpler structure than the second sensor 38, and thus is less expensive than the second sensor 38. However, since the first sensor 36 performs detection based on the output voltage from one light-receiving portion, the first sensor 36 is more likely to be affected by, for example, the moving speed of the carriage. Further, in the print apparatus 10, the moving speed of the carriage 32 in which the first sensor 36 is provided changes depending on the print mode, the image pattern, and the like. Thus, there is a possibility that the detection accuracy of the first sensor 36 changes.

[0132] The third embodiment differs from the above-described first embodiment in that a change in the moving speed of the first sensor 36 at the time of detecting the end portion of the print medium M is suppressed to suppress a change in the detection accuracy of the first sensor 36. In the following description, the "moving speed of the first sensor 36 at the time of detecting (passing through) the end portion of the print medium M" means the speed at which the first sensor 36 moves via the carriage 32 at the time of detecting (passing through) the end portion of the print medium M. In other words, the "moving speed of the first sensor 36 at the time of detecting (passing through) the end portion of the print medium M" means the moving speed of the carriage 32 at the time of detecting (passing through) the end portion of the print medium M by the first sensor 36.

[0133] <Micro-Margin Printing>

[0134] Next, an explanation is given of the size of the print image and the print start position in the X direction at the time of performing micro-margin printing which can obtain a similar visual effect to that of marginless printing. Figure 15A and Figure 15B are diagrams illustrating the size of the print image and the print start position in the X direction with respect to the print medium M in micro-margin printing. Figure 15A The print start position is illustrated in the case where the carriage 32 moves (scans) in the advancing direction, and Figure 15B The print start position is illustrated in the case where the carriage 32 moves in the retreating direction. Note that, in Figure 16A and Figure 16B the illustration of the second sensor 38 is omitted for ease of understanding.

[0135] Due to skewing of the print medium M caused by conveyance, and stretching of the print medium M with respect to a nominal value caused by humidity or the like, the end portion position of the print medium M in the X direction sometimes deviates. Therefore, in micro-margin printing in which a print image is printed very close to the edge of the print medium M, for example, the print image Ig is generated so that the print image Ig is enlarged by a predetermined amount Ti in the X direction compared with the print medium M. Then, the timing of ejection of ink from each nozzle array is adjusted, and printing is performed from a position very close to the end portions EL and ER of the print medium M. Note that the user can select whether or not to perform micro-margin printing. Note that, for example, the position information immediately obtained is used for the end portions EL and ER.

[0136] <Moving Speed of First Sensor>

[0137] Next, a change in the moving speed of the first sensor 36 at the time of scanning for printing is explained. Figure 16A and Figure 16B are diagrams illustrating a change in the moving speed of the first sensor 36 at the time of scanning for printing depending on a difference in the nozzle array from which ink is ejected. Figure 16AThis is a diagram illustrating the change in the moving speed of the first sensor 36 when ink is ejected from the nozzle array located at the downstream end of the moving direction of the carriage 32. Figure 16A This is an example of something located at... Figure 16A A graph showing the change in the moving speed of the first sensor 36 when ink is ejected from the nozzle array upstream in the moving direction.

[0138] When printing an image Ig on a printing medium M, the moving speed of the carriage 32 reaches a predetermined speed Sp before the printing of the image Ig, remains at the predetermined speed Sp during the printing of the image Ig, and decreases from the predetermined speed Sp after the printing of the image Ig.

[0139] Specifically, during the scan involving printing in the backward direction (-X direction), the carriage 32 begins to move from a stop position on the other side in the X direction, and the moving speed of the carriage 32 gradually increases, reaching a predetermined speed Sp at the timing of the start of printing of the printed image Ig. Then, during the printing of the printed image Ig, the moving speed of the carriage 32 is maintained at the predetermined speed Sp. Next, the moving speed of the carriage 32 decreases at the timing of the end of printing of the printed image Ig, and gradually decreases until the carriage 32 stops at a stop position on one side in the X direction.

[0140] Since the first sensor 36 is disposed within the carriage 32, it moves at the same speed as the carriage 32. Note that within the carriage 32, the first sensor 36 is located downstream of the nozzle array of the printhead 12 in the backward direction. However, at the timing of the end of printing the image Ig, when the first sensor 36 is located upstream of the end ER of the printing medium M in the X direction in the moving direction, the first sensor 36 decelerates before detecting the end ER (see [link]). Figure 16B ).

[0141] Furthermore, the closer the nozzle array ejecting ink is in the X direction to the first sensor 36 during the printing of the image Ig, the earlier the deceleration of the first sensor 36 begins. For example, when printing the image Ig using the downstream nozzle array 1602 in the printhead 12 located in the backward direction, the first sensor 36 begins to decelerate from coordinate PA (see...). Figure 6 On the other hand, when printing the image Ig using the nozzle array 1604 located upstream in the backward direction of the nozzle array 1602 in the printhead 12, the first sensor 36 begins to decelerate from the coordinate PB located downstream in the backward direction of coordinate PA (see...). Figure 17ATherefore, the moving speed Sp1 of the first sensor 36 when passing the end ER while decelerating from coordinate PA is lower than the moving speed Sp2 of the first sensor 36 when passing the end ER while decelerating from coordinate PB. As described above, the moving speed of the first sensor 36 when passing the end of the printing medium M varies according to the position of the nozzle array printing at the end position of the printing medium M in the X direction.

[0142] As described above, the detection of the end position of the printing medium M by the first sensor 36 is based on a value corresponding to the amount of light received in the light-receiving portion 304 during the movement of the carriage 32. Therefore, if the moving speed of the first sensor 36 changes before reaching the end ER while passing the end ER, the output voltage reaches a threshold (see [reference]) compared to the case where the moving speed does not change. Figure 17B The coordinates change more significantly when the movement speed remains constant. This causes the detected end position to deviate from the end position it would have been if the movement speed had remained constant.

[0143] <Change of Stop Position>

[0144] Therefore, in this embodiment, the stop position of the carriage 32 involved in the scanning process for detecting the end of the printing medium M is changed so that the moving speed of the first sensor 36 when passing the end does not decrease from the moving speed during the printing of the printed image Ig. Specifically, the stop position of the carriage 32 during scanning is shifted downstream in the moving direction during scanning. (Refer to the following...) Figure 17A and Figure 17B A summary of the change in the stopping position. Figure 17A and Figure 17B This is a diagram illustrating the general change in the stopping position of carriage 32.

[0145] Assume that the printed image Ig is printed by ejecting ink from the nozzle array 1702 of the printhead 12 onto the printing medium M. In this case, the stop position of the carriage 32 changes to the set stop position SP (see...). Figure 17B The predetermined position PP downstream of the carriage 32 in the direction of movement (see) Figure 18 ).

[0146] Specifically, the predetermined position PP is the position corresponding to the end ER of the printing medium M. ER Downstream of the carriage 32 in the direction of movement, and with position P ERThe deceleration distance Sdd of the carriage 32 is separated. Note that the deceleration distance Sdd of the carriage 32 is the distance traveled by the carriage 32 from the start of deceleration until it stops, or a distance longer than that by a fixed amount. The moving speed of the first sensor 36 when it passes the end ER of the printing medium M is thus not reduced from the predetermined speed Sp during the printing of the printed image Ig.

[0147] Note that the predetermined location PP only needs to be a location that is at least at location P. ER Downstream of the carriage 32 in the direction of movement and with position P ER The deceleration distance Sdd is separated. Therefore, the predetermined position PP could be, for example, at position Px ( Figure 18 The position downstream of the carriage 32 in the direction of movement and separated from position Px by a deceleration distance Sdd, which is at position P. ER Downstream in the direction of movement. Furthermore, the deceleration distance Sdd can be determined experimentally, for example, based on the moving speed of the carriage 32.

[0148] <Change Processing>

[0149] Next, the process of changing the stop position of carriage 32 will be explained. Figure 18 This is a flowchart illustrating the details of the process for changing the stop position of carriage 32. The main controller 400 performs this process by expanding and executing the program code stored in flash ROM 402 onto RAM 404. Figure 11 The series of processes illustrated in the flowchart. Alternatively, Figure 18 Some or all of the functions of the steps in the process can be performed by hardware such as ASICs or electrical circuits.

[0150] In the case of performing micro-margin printing in bidirectional printing, the printing process is immediately adjacent to the printing process (see...). Figure 19 Execute before S1104 processing in ) Figure 19 Change processing is performed. Specifically, change processing is performed on each operation of the scan immediately before the scan involving printing is executed. Note that change processing is not performed if the printing being performed is not micro-margin printing.

[0151] When the processing is changed, firstly, in S1802, the main controller 400 determines whether the variable n, which indicates the number of times the scan involving printing is executed, is odd. In this embodiment, a first sensor 36 is provided on one side of the carriage 32 and a second sensor 38 is provided on the other side of the carriage 32. In the second sensor 38, the end EL of the printing medium M can be accurately obtained regardless of the carriage's moving speed by using a differential signal based on the output signals from the first light-receiving unit 322 and the second light-receiving unit 324. Therefore, in the scanning involving printing that detects the advancing direction of the end EL of the printing medium M using the second sensor 38, it is not necessary to change the stop position of the carriage 32.

[0152] Therefore, if the main controller 400 determines that the variable n is odd, it determines that the nth scan involving printing is a scan involving printing detected by the second sensor 38 in the forward direction of the end EL of the printing medium M, and terminates the change process. On the other hand, if the main controller 400 determines that the variable n is even (that is, not odd) in S1802, it determines that the nth scan involving printing is a scan involving printing detected by the first sensor 36 in the backward direction of the end ER of the printing medium M, and proceeds to S1804. In S1804, the main controller 400 obtains the position (coordinates) of the end ER. The obtained position of the end ER is the position information (coordinate information) obtained in the preceding backward scan involving printing.

[0153] Note that when the variable is "2", the scan involving printing in the immediate backward direction is not performed. Therefore, for example, before performing actual printing based on the print job, a scan of carriage 32 in the backward direction is performed, and the position of the end ER of the print medium M is obtained in this scan. Thus, in S1804, when the variable n is "2", the position information of the end ER obtained by the scan performed before printing is obtained.

[0154] Subsequently, in S1806, the main controller 400 changes the stop position of the carriage 32 during the nth scan involving printing based on the position of the end ER obtained in S1804 and the pre-stored deceleration distance Sdd, and terminates the change process. Specifically, in S1806, the stop position of the carriage 32 during the nth scan involving printing is determined to be downstream of the position of the end ER obtained in S1804 in the backward direction and separated from the position of the end ER obtained in S1804 by the deceleration distance Sdd. In other words, in S1806, the coordinate information of the stop position of the carriage 32 is obtained by adding the deceleration distance Sdd to the coordinate information of the end ER in the X direction.

[0155] Note that the moving speed of the carriage 32 during printing varies depending on the printing mode, etc. Therefore, in the printing device 10, for example, a deceleration distance Sdd corresponding to each moving speed of the carriage 32 in each printing mode is stored in the storage area. Thus, the deceleration distance Sdd used in S1806 is determined based on the printing mode, etc.

[0156] <Variation Example>

[0157] As described above, the second sensor 38 is configured to detect the end of the printing medium M using only the third light-receiving part 326. Specifically, the second sensor 38 can operate in a detection mode (single mode) using a detection mechanism similar to that of the first sensor 36. Therefore, in this case, it is also necessary to change the stop position of the carriage 32 during the scanning involving printing in the forward direction. The change process when the second sensor 38 operates in single mode will be described below.

[0158] Figure 19 This is a flowchart illustrating the details of the change processing when the second sensor 38 operates in single mode. The main controller 400 performs this process by expanding the program code stored in the flash ROM 402 onto the RAM 404 and executing that program code. Figure 19 The series of processes illustrated in the flowchart. Alternatively, Figures 20A-21 Some or all of the functions of the steps in the process can be performed by hardware such as ASICs or electrical circuits.

[0159] At the beginning Figure 20A In the case of a change in processing, firstly, in S1902, the main controller 400 determines whether the variable n, which indicates the number of times the scan involving printing has been executed, is odd. If the main controller 400 determines in S1902 that the variable n is odd, the process proceeds to S1904, and the main controller 400 obtains the position (coordinates) of the end EL. The obtained position of the end EL is the position information (coordinate information) obtained in the scan involving printing in the immediately preceding forward direction.

[0160] Note that when variable n is "1", the scanning involving printing in the immediate forward direction is not performed. Therefore, for example, before performing actual printing based on a print job, a scan of carriage 32 is performed in both the forward and backward directions, and the positions of the ends ER and EL of the print medium M are obtained in this scan. Thus, when variable n is "1", the position information of the end EL obtained by this scan performed before printing is obtained.

[0161] Subsequently, in S1906, the main controller 400 changes the stop position of the carriage 32 during the nth scan involving printing based on the position of the end EL obtained in S1904 and the pre-stored deceleration distance Sdd, and terminates the change process. Specifically, in S1906, the stop position of the carriage during the nth scan involving printing is determined to be downstream of the position of the end EL obtained in S1904 in the forward direction and separated from the position of the end EL obtained in S1904 by the deceleration distance Sdd. In other words, in S1906, the coordinate information of the stop position of the carriage 32 is obtained by adding the deceleration distance Sdd to the coordinate information of the end EL in the X direction.

[0162] Note that the moving speed of the carriage 32 during printing varies depending on the printing mode, etc. Therefore, in the printing device 10, for example, a deceleration distance Sdd corresponding to the respective moving speed of the carriage 32 in each printing mode is maintained in the storage area. Thus, the deceleration distance Sdd used in S1906 and S1910, which will be described later, is determined based on the printing mode, etc.

[0163] On the other hand, if the main controller 400 determines in S1902 that the variable n is not odd (that is, even), then the process proceeds to S1908, and the main controller 400 obtains the position (coordinates) of the end ER. The obtained position of the end ER is the position information (coordinate information) obtained in the preceding backward scan related to printing. Note that when the variable n is "2", the preceding backward scan related to printing is not performed. Therefore, when the variable is "2", the position information of the end ER obtained in the aforementioned scan performed before printing is obtained.

[0164] Subsequently, in S1910, the main controller 400 changes the stop position of the carriage 32 during the nth scan involving printing based on the position of the end ER obtained in S1908 and the pre-stored deceleration distance Sdd, and terminates the change process. Specifically, in S1910, the stop position of the carriage 32 during the nth scan involving printing is determined to be downstream of the position of the end ER obtained in S1908 in the backward direction and separated from the position of the end ER obtained in S1908 by the deceleration distance Sdd. In other words, in S1910, the coordinate information of the stop position of the carriage 32 is obtained by adding the deceleration distance Sdd to the coordinate information of the end ER in the X direction.

[0165] <Variation Example>

[0166] In the above description, the stop position of the carriage 32 is changed during a scan involving printing in the backward direction detected by the first sensor 36 at the end ER. However, this disclosure is not limited to this. For example, the stop position of the carriage 32 can be changed if the main controller 400 determines that a change in the stop position is necessary based on factors such as the size of the printed image Ig, the position of the end of the printed image Ig relative to the end ER, and the position of the ink ejection nozzle array in the X direction.

[0167] In the above description, the change in the stop position of the carriage 32 is performed when the end ER is detected using the first sensor 36. However, the execution of the change is not limited to this case. For example, the change can be performed when the end EL of the printing medium M is detected in a single mode of the second sensor 38.

[0168] <Operation and Effects>

[0169] As described above, in this embodiment, the printing device 10 changes the stop position of the carriage 32 during the scan involving printing by using a first sensor 36 (whose detection accuracy varies according to the change in moving speed as it passes the end of the printing medium M). Specifically, a position downstream of the end position in the scanning direction and separated from the end position by a deceleration distance Sdd is set as the stop position of the carriage 32, which takes into account the deceleration of the carriage 32 until the stop position. In the printing device 10, the moving speed when the first sensor 36 passes the end is thus not reduced from the printing speed of the printed image, and changes in the detection accuracy of the first sensor 36 are unlikely to occur.

[0170] (Fourth Embodiment)

[0171] Next, refer to Figure 20B The printing apparatus according to the fourth embodiment is described below. In the following description, structures that are the same as or corresponding to the printing apparatus according to the first embodiment are indicated by the same reference numerals used in the first embodiment, and their detailed descriptions are omitted.

[0172] The fourth embodiment differs from the third embodiment in that the detection result of the first sensor 36 is corrected to suppress the change in the detection accuracy of the first sensor 36 caused by the moving speed when passing through the end of the printing medium M.

[0173] As described above, in the printing device 10, the scanning involved in printing is repeatedly performed multiple times to print a print image Ig based on the print data. Therefore, assuming the conditions are constant, even if the moving speed of the first sensor 36 as it passes the end of the print medium M decreases from the moving speed during the printing of the print image Ig, the number of units involved in the scanning will not change. Specifically, the value of the speed of the first sensor 36 as it passes the end of the print medium M is the same between the operations involving the scanning. Conditions include, for example, the condition that the nozzle array ejecting ink is fixed (see...). Figure 20A ), and the condition that the length of the printed image Ig in the X direction is constant (see Figure 21 )wait.

[0174] Therefore, in this embodiment, the end position obtained based on the detection result of the first sensor 36 is corrected based on the speed difference between the moving speed of the printed image Ig during printing and the moving speed when passing the end of the printing medium M. The correction method is described in detail below.

[0175] The scanning speed of carriage 32 (the predetermined speed Sp mentioned above) is determined based on printing conditions such as the printing mode. When the scanning speed of carriage 32 is determined, the acceleration region AC, the constant speed region CV, and the deceleration region DE are determined (see...). Figure 21 Then, the moving speed of the first sensor 36 when passing the end of the printing medium M can be obtained based on the size of the printing medium M, the length of the printed image Ig in the X direction, printing conditions such as the type of ink, and the aforementioned deceleration region DE.

[0176] Furthermore, the printing device 10 maintains data in the flash ROM 402 indicating the relationship between: the reference speed and the moving speed of the first sensor 36 as it passes the end of the printing medium M; and the error in the obtained position of that end. In the printing device 10, the moving speed of the carriage 32 is fixed during printing, and the data covers the entire range of that moving speed. Furthermore, the reference speed can be any speed at which the carriage 32 can move.

[0177] Specifically, the data maintained is data used to indicate the correction amount, wherein the moving speed in the constant speed region interval CV is used as a reference, and the obtained end position is corrected by the correction amount based on the difference between the moving speed in the interval CV and the moving speed of the first sensor 36 when passing the end of the printing medium M.

[0178] Figure 21 Examples of data used to indicate the relationship between speed difference and correction amount are provided. Figure 21During printing, the carriage 32 can move at a speed (scanning speed) ranging from 10 IPS (inches per second) to 40 IPS, with a base speed of 25 IPS.

[0179] Given that the moving speed of the first sensor 36, obtained under various printing conditions, is 35 IPS, the difference from the reference speed is "+10 (=35-25) IPS", and based on... Figures 22A-25B The data corresponds to a correction of "+100μm". Therefore, in this case, 100μm is added to the position of the end of the printing medium M obtained based on the detection result of the first sensor 36. Furthermore, when the moving speed of the first sensor 36 obtained based on various printing conditions is 15IPS, the difference from the reference speed is "-10 (=15-25)IPS", and based on... Figure 22A The data corresponds to a correction value of "-50μm". Therefore, in this case, 50μm is subtracted from the position of the end of the printing medium obtained from the detection result based on the first sensor 36.

[0180] <Variation Example>

[0181] Although not specifically described above, the printing device 10 may, for example, be configured to selectively execute the techniques according to the third embodiment and the fourth embodiment based on various printing conditions. Specifically, when the moving speed of the first sensor 36 as it passes the end of the printing medium is lower than a predetermined speed, the correction error is large. Therefore, the stopping position of the carriage 32 is changed using the technique of the third embodiment. On the other hand, when the moving speed is equal to or higher than the predetermined speed, the position of the end of the printing medium M obtained based on the detection result of the first sensor 36 is corrected using the technique of the fourth embodiment. Note that the moving speed of the first sensor 36 as it passes the end of the printing medium M is obtained based on the printing conditions.

[0182] Therefore, when a print job is input in this situation, the printing device 10 first determines whether the following condition is met based on the printing conditions: the moving speed of the first sensor 36 is constant when passing the end of the print medium M during the printing process. If the printing device 10 determines that the condition of constant moving speed is met, the printing device 10 obtains the moving speed of the first sensor 36 when passing the end of the print medium M based on the printing conditions, and determines whether the obtained moving speed is equal to or higher than a predetermined speed. Then, if the printing device 10 determines that the moving speed is equal to or higher than the predetermined speed, it corrects the position of the end of the print medium M obtained in each scan operation involving printing based on the maintained data. On the other hand, if the printing device 10 determines that the moving speed is lower than the predetermined speed, it changes the stop position of the carriage 32 in each scan operation involving printing.

[0183] In the above description, the correction of the detection position is not limited to being performed when detecting the end ER using the first sensor 36. For example, the correction can be performed when detecting the end EL of the printing medium M in a single mode using the second sensor 38.

[0184] (Fifth Embodiment)

[0185] Next, refer to Figure 22A The printing apparatus according to the fifth embodiment is described below. In the following description, structures that are the same as or corresponding to the printing apparatus according to the first embodiment are indicated by the same reference numerals used in the first embodiment, and their detailed descriptions are omitted.

[0186] As described above, the printing device 10 detects the end position of the printing medium M based on changes in a differential signal corresponding to the output of the second sensor 38, which is an optical sensor. However, due to various factors, abnormal or unnecessary outputs may occur in some cases between the output voltage from the second sensor 38 and the differential signal output from the differential amplifier 332. In this embodiment, even in the event of such an anomaly in the output, a position close to the actual end position of the printing medium M can be obtained as the end position of the printing medium M.

[0187] <First Form>

[0188] As described above, since the second sensor 38 is an optical sensor, when ink contamination, paper scraps, or reflective material adheres to the printing medium M and the platen 34, a pulse caused by the adhered material is formed in the waveform used to indicate the change of the differential signal Vout.

[0189] For example, near the end of the printing medium M supported on the platen 34, there may be contaminants such as dust or ink adhering to the printing medium M or the platen 34. In this case, in the output waveform used to indicate changes in the differential signal Vout, a pulse caused by this contamination is formed separately from the pulse corresponding to the end of the printing medium M (see...). Figure 22A ). Figure 22B This is a diagram illustrating the output waveform, which indicates the change in the differential signal Vout when contaminants such as dust or ink adhere to the printing medium M or the platform 34 near the end of the printing medium M supported on the platform 34. Note that in Figure 24A , Figure 24B , Figure 24C , Figure 24D , Figure 25A , Figure 25B , Figure 22B and Figure 22BThe shape of the output waveform (pulse waveform) used to indicate changes in the differential signal Vout is illustrated in a simplified manner for ease of understanding.

[0190] In this situation, for example, if the width of the pulse caused by contamination is approximately the same as the width of the pulse corresponding to the end of the printing medium M, there is a possibility that the end of the printing medium M in the X direction cannot be accurately detected using the technique described above according to the second embodiment. Note that the pulse width means the distance between two points through which the differential signal Vout in a pulse passes the first threshold Th1.

[0191] Obtain a summary of the end position of the printing media.

[0192] Therefore, in the first form of the fifth embodiment, when the pulse generated by contamination and the pulse corresponding to the end of the printing medium M are generated to have similar widths as described above, the end position of the printing medium in the X direction can also be accurately obtained.

[0193] Specifically, in this embodiment, a detection range is set, and pulses outside this detection range are excluded from the pulses corresponding to the end of the printing medium M (see [link]). Figure 23 ). Figure 23 This diagram illustrates pulses excluded when a detection range is set. The detection range is the width (X-direction) of the printing medium M and is set based on the reference position during printing medium transport (the transport position of the printing medium) and the size of the printing medium to be used. Alternatively, this structure allows the position of the printing medium M transported by the transport unit to be read in advance using the first sensor 36 or the second sensor 38, and the detection range to be determined based on the read information. Note that, as specific coordinate values, for example, the coordinate values ​​of one side and the other side of the detection range in the X-direction are determined when the alignment position of the carriage 32 is the origin.

[0194] For example, if the reference position when conveying the printing medium M is one end of the conveying path in the X direction, a first position corresponding to that end and a second position separated from that end by the size of the printing medium M to be used are obtained. Then, a predetermined range with respect to the first position is set as a detection range corresponding to one end, and a predetermined range with respect to the second position is set as a detection range corresponding to the other end.

[0195] Furthermore, when the reference position for conveying the printing medium M is at the center of the conveying path in the X direction, the positions of two points centered on this center position and separated from each other in the X direction by a distance corresponding to the size of the printing medium M to be used are obtained. Then, a predetermined range for one of these positions is set as a detection range corresponding to one end, and a predetermined range for the other position is set as a detection range corresponding to the other end.

[0196] For example, a predetermined range is determined based on the distance between the first light-receiving portion 322 and the second light-receiving portion 324. Specifically, for example, the predetermined range is set to be a range longer than a predetermined amount compared to that distance. Note that when the second sensor 38 is configured to detect only one end of the printing medium M, only the detection range corresponding to that one end is set.

[0197] Get processed

[0198] Next, in this embodiment, a description of the process for obtaining the end of the printing medium M from the differential signal Vout of the differential amplifier 332 in differential mode will be given. Note that the obtaining process described below begins after the start of the nth scan involving printing in S1104 in the above-described printing process, and is performed, for example, in S1108.

[0199] Figure 23 This is a flowchart illustrating the details of the process for obtaining the end of the printing medium M based on the differential signal Vout in this embodiment. The main controller 400 performs this process by expanding the program code stored in the flash ROM 402 onto the RAM 404 and executing the program code. Figure 23 The series of processes illustrated in the flowchart. Alternatively, Figure 24A Some or all of the functions of the steps in the process can be performed by hardware such as ASICs or electrical circuits.

[0200] Upon initiating processing, firstly, in S2302, the main controller 400 determines whether the differential signal Vout of the acquired differential amplifier 332 has passed the first threshold Th1. If, in S2302, the main controller 400 determines that the differential signal Vout has not passed the first threshold Th1, then the processing proceeds to S2310, which will be described later. On the other hand, if, in S2302, the main controller 400 determines that the differential signal Vout has passed the first threshold Th1, then the processing proceeds to S2304, and the main controller 400 determines whether the previously acquired coordinates are the first coordinates.

[0201] If, in S2304, the main controller 400 determines that the coordinates obtained immediately before are not the first coordinates, then the process proceeds to S2306, whereby the main controller 400 retains the coordinates obtained in S2302 as the first coordinates, and the process proceeds to S2310. Conversely, if, in S2304, the main controller 400 determines that the coordinates obtained immediately before are the first coordinates, then the process proceeds to S2308, whereby the main controller 400 retains the coordinates obtained in S2302 as the second coordinates, and the process proceeds to S2310. Note that in S2308, the retained second coordinates are associated with the first coordinates obtained immediately before.

[0202] In S2310, the main controller 400 determines whether the carriage 32 has moved to the stop position. Note that since the specific content of the processing from S2302 to S2310 is the same as that of the processing from S1402 to S1410 described above, its detailed explanation is omitted. If the main controller 400 determines in S2310 that the carriage 32 has not moved to the stop position, the processing returns to S2302. On the other hand, if the main controller 400 determines in S2310 that the carriage 32 has moved to the stop position, the processing proceeds to S2312, and the main controller 400 obtains a pair of first and second coordinates as the true values ​​of the coordinates based on the obtained first and second coordinates from the pre-set detection range.

[0203] In S2312, the first and second coordinates, which are related to each other and both within the detection range, are obtained as true values ​​for the coordinates. Note that the detection range is stored in the storage area. Then, in S2314, the main controller 400 obtains the end of the printing medium M based on the first and second coordinates set as true values ​​and terminates the acquisition process. Since the specific content of the process in S2314 is the same as that in S1414 described above, its detailed description is omitted.

[0204] Variations

[0205] exist Figure 24A In the acquisition process, the coordinates of the differential signal Vout passing through the first threshold Th1 are obtained, and the position of the end of the printing medium M is obtained based on two related coordinates within the detection range. However, this disclosure is not limited to this. For example, this structure allows the printing device 10 to monitor whether the coordinates are within the detection range, and if the coordinates are within the detection range, obtain the coordinates of the differential signal Vout that have passed through the first threshold Th1, and if the coordinates are outside the detection range, not obtain the coordinates. Furthermore, in the case where multiple pairs of related first and second coordinates are generated within the detection range in the S2312 process, for example, by using the technique of the second embodiment described above, the coordinates of the pair whose distance between the two coordinates is closest to the theoretical value can be obtained as the true value.

[0206] <Second Form>

[0207] Next, the second form of the fifth embodiment will be described. Similarly, as described in the second embodiment above, there is a situation where, in the output waveform of the differential amplifier 332, near the pulse corresponding to the end of the printing medium M, a micro-pulse is formed due to fluctuations or noise in the sensor signal. Due to the influence of this micro-pulse as described above, there is a possibility that the end of the printing medium M in the X direction cannot be accurately detected. Specifically, for example, there is a possibility that the midpoint between the two points of the differential signal Vout obtained from the initial micro-pulse and the first threshold Th1 is taken as the end of the printing medium M (see...). Figure 24B ). Figure 23 This is a diagram illustrating the output waveform, which represents the variation of the differential signal Vout, which forms micropulses (chattering) near the pulse waveform corresponding to the end of the printing medium M.

[0208] Specific techniques in this form

[0209] Therefore, in the second form, the midpoint between the position (point) where the differential signal Vout initially exceeds the first threshold Th1 within the detection range set in the first form and the position (point) where the differential signal Vout finally drops below the first threshold Th1 is obtained as the end position of the printing medium M in the X direction (see [reference]). Figure 24C In this case, for example, in Figure 24C In the processing step S2308, the maintained second coordinate does not necessarily need to be associated with the last obtained first coordinate. Furthermore, in S2312, the initial first coordinate and the last second coordinate obtained within the detection range are obtained as the true values ​​of the coordinates.

[0210] Furthermore, in this case, the micro-pulses occurring before and after the pulse corresponding to the end of the printing medium cause the distance between the coordinates obtained as the truth value to be larger than the width of the pulse corresponding to the end of the printing medium M. However, compared to not using the second form of technique, and obtaining the position of the end of the printing medium M as the midpoint between the two points of the differential signal Vout passing through the first threshold Th1 in the initially occurring micro-pulse (see...). Figure 24D Compared to the previous case, the error is smaller. Furthermore, since the jitter occurs at high speed (within a short timeframe), the error is negligible even when the jitter portion is included within the pulse to be detected (the two points used to obtain the midpoint).

[0211] In the technique according to the second form, the situation where the position of the end of the printing medium M is detected based on, for example, a micropulse that initially occurs within the detection range does not occur (see...). Figure 25AFurthermore, the situation where the position of the end of the printing medium M is detected outside the detection range based on the position where the differential signal Vout finally drops below the threshold does not occur (see [reference]). Figure 25B ).

[0212] <Third Form>

[0213] Next, the third form of the fifth embodiment will be described. There exists a situation where signal degradation occurs in the differential signal Vout due to light reflection caused by contamination or the like on the platform 34, and the distance between the two points where the differential signal Vout initially crosses the threshold and last crosses the threshold becomes shorter or longer than this distance would be in the case where no signal degradation occurs. In this situation, the position of the end of the printing medium M cannot be accurately detected.

[0214] Specific techniques in this form

[0215] Therefore, in the third form, the pulse width of the pulse corresponding to the end of the printing medium M is set, and the obtained pulse width is corrected if the pulse width of the obtained pulse is shorter (or longer) than the set pulse width by detection. See below for reference. Figure 25A and Figure 25B Detailed explanations are provided. Figure 25A and Figure 25B These are figures illustrating the specific technical content of the third form of the fifth embodiment. Figure 25A This is a diagram illustrating the technique used when the pulse width obtained during detection is short, and Figure 25B This is a diagram illustrating the technique used when the pulse width obtained during detection is long.

[0216] Specifically, the pulse width of the pulse corresponding to the end of the printing medium M is set based on the positional relationship between the first light-receiving part 322 and the second light-receiving part 324 (that is, the distance in the X direction between the center position of the first light-receiving part 322 and the center position of the second light-receiving part 324). A set value (setting range) is set to the range where the distance between the position where the differential signal Vout exceeds the first threshold Th1 and the position where the differential signal Vout drops below the first threshold Th1 in the pulse corresponding to the end of the printing medium M is considered an allowable distance. Furthermore, a correction value is set to correct for the position where the differential signal Vout drops below the first threshold Th1. This correction value is a value corresponding to the positional relationship between the first light-receiving part 322 and the second light-receiving part 324, and is, for example, a value that separates the position where the differential signal Vout drops below the first threshold Th1 from the position where the differential signal Vout exceeds the first threshold Th1 by a distance that allows the position of the end of the printing medium M to be appropriately obtained. Note that this correction value is at least a value within the range set to the set value. This correction value is determined, for example, through experimentation, depending on the type of printing medium M.

[0217] Assume that the width of the pulse obtained by detection corresponding to the end of the printing medium M (that is, the distance between the position where the differential signal Vout exceeds the first threshold Th1 and the position where the differential signal Vout drops below the first threshold Th1) is less than the lower limit of the set pulse width. In this case, based on the set correction value, the position where the differential signal Vout drops below the first threshold Th1 moves in a direction separate from the position where the differential signal Vout exceeds the first threshold Th1, such that the distance between the position where the differential signal Vout exceeds the first threshold Th1 and the position where the differential signal Vout drops below the first threshold Th1 becomes the correction value (see [reference]). ​ Then, the end position of the printing medium M is obtained based on the position where the differential signal Vout exceeds the first threshold Th1 and the position where the differential signal Vout drops below the first threshold Th1 after the movement. Specifically, in this case, for the position where the differential signal Vout exceeds the first threshold Th1, the position where the differential signal Vout drops below the first threshold Th1 is corrected based on a correction value, and the distance between the position where the differential signal Vout exceeds the first threshold Th1 and the position where the differential signal Vout drops below the first threshold Th1 is thus increased from the distance before correction.

[0218] Furthermore, it is assumed that the distance between the position where the differential signal Vout exceeds the first threshold Th1 and the position where the differential signal Vout drops below the first threshold Th1 in the pulse corresponding to the end of the printing medium M is greater than the upper limit of the set pulse width. In this case, based on the set correction value, the position where the differential signal Vout drops below the first threshold Th1 moves in the direction toward the position where the differential signal Vout exceeds the first threshold Th1, such that the distance between the position where the differential signal Vout exceeds the first threshold Th1 and the position where the differential signal Vout drops below the first threshold Th1 becomes the correction value (see [reference]). ​ Then, the end position of the printing medium M is obtained based on the position where the differential signal Vout exceeds the first threshold Th1 and the position where the differential signal Vout drops below the first threshold Th1 after the movement. Specifically, in this case, for the position where the differential signal Vout exceeds the first threshold Th1, the position where the differential signal Vout drops below the first threshold Th1 is corrected based on a correction value, and the distance between the position where the differential signal Vout exceeds the first threshold Th1 and the position where the differential signal Vout drops below the first threshold Th1 is thus reduced from the distance before correction.

[0219] Specifically, when the distance between the position where the differential signal Vout exceeds the first threshold Th1 (which is the pulse width) and the position where the differential signal Vout drops below the first threshold Th1 is outside the range of the set value, the position where the differential signal Vout drops below the first threshold Th1 is moved to a position where the correction value is separated from the position where the differential signal Vout exceeds the first threshold Th1. Note that when using the technique of the second form described above, "the position where the differential signal Vout exceeds the first threshold Th1" in the above description refers to "the position where the differential signal Vout initially exceeds the first threshold Th1," and "the position where the differential signal Vout drops below the first threshold Th1" in the above description refers to "the position where the differential signal Vout finally drops below the first threshold Th1."

[0220] In the above description, when the distance between the position where the differential signal Vout exceeds the first threshold Th1 and the position where the differential signal Vout drops below the first threshold Th1 is outside the range of the set value, the differential signal Vout is moved to the position where it drops below the first threshold Th1. However, this disclosure is not limited to this. The position where the differential signal Vout exceeds the first threshold Th1 can be moved to a position where the correction value is separated from the position where the differential signal Vout drops below the first threshold Th1. For example, suppose there is a situation such as the platform 34 being dirtier than the printing medium M. In this case, if the second sensor 38 detects the end of the printing medium M while moving in the X direction from the printing medium M side toward the platform 34 side, the differential signal Vout is moved to the position where it drops below the first threshold Th1. Furthermore, in this case, if the second sensor 38 detects the end of the printing medium M while moving in the X direction from the platform 34 side toward the printing medium M side, the differential signal Vout is moved to the position where it exceeds the first threshold Th1.

[0221] <Operation and Effects>

[0222] As described above, in the first embodiment of this example, a detection range is provided for detecting pulses corresponding to the end of the printing medium M, and pulses formed outside this detection range are excluded when obtaining the position of the end of the printing medium M. Furthermore, in the second embodiment of this example, the coordinates of the midpoint between the position where the differential signal Vout initially exceeds the first threshold Th1 and the position where the differential signal Vout finally drops below the first threshold Th1 within the detection range are obtained as the position of the end of the printing medium M. Furthermore, in the third embodiment of this example, if the width of the pulse corresponding to the end of the printing medium M is less than the lower limit of a set value or greater than the upper limit of a set value, the differential signal Vout is moved to a position below the first threshold Th1 based on a correction value. In this embodiment, even in the event of anomalies in the outputs from the second sensor 38 and the differential amplifier 332, a position close to the actual end position of the printing medium M can be obtained as the end position of the printing medium M.

[0223] (Other embodiments)

[0224] Embodiments of this disclosure can also be implemented by a computer of a system or device that includes a storage medium (also more fully referred to as a "non-transitory computer-readable storage medium") recording computer-executable instructions (e.g., one or more programs) to perform one or more functions in the above embodiments and / or includes one or more circuits (e.g., application-specific integrated circuits (ASICs)) for performing one or more functions in the above embodiments, and by the following method, wherein the computer of the system or device performs the above methods by, for example, reading from the storage medium and executing computer-executable instructions to perform one or more functions in the above embodiments and / or controlling the one or more circuits to perform one or more functions in the above embodiments. The computer may include one or more processors (e.g., a central processing unit (CPU), a microprocessor unit (MPU)) and may include a network of separate computers or separate processors to read and execute the computer-executable instructions. These computer-executable instructions may, for example, be provided to the computer from a network or storage medium. The storage medium may include one or more of the following: hard disk, random access memory (RAM), read-only memory (ROM), storage unit of a distributed computer system, optical disc (such as compact disc (CD), digital versatile disc (DVD) or Blu-ray disc (BD)™), flash storage device and memory card.

[0225] While this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The scope of the appended claims is to be interpreted in the broadest sense to include all such modifications and equivalent constructions and functions.

[0226] According to this disclosure, the increase in the time required for printing can be suppressed.

Claims

1. A printing device, comprising: A support unit configured to support the delivered printing medium; A carriage in which a printhead is mounted, the printhead being configured to print by ejecting ink onto the printing medium, the carriage being movable in the width direction of the printing medium intersecting the transport direction of the printing medium; A first detection unit is disposed on one side of the carriage in the width direction and is capable of detecting the end of the printing medium in the width direction; as well as A second detection unit is disposed on the other side of the carriage in the width direction and is capable of detecting the end of the printing medium in the width direction. Wherein, at least one of the first detection unit and the second detection unit includes: A light-emitting unit is configured to emit light toward the support unit and the printing medium supported on the support unit; A first light-receiving unit is capable of receiving reflected light from the support unit and the printing medium supported on the support unit; and The second light-receiving unit is capable of receiving reflected light from the support unit and the printing medium supported on the support unit. The second light-receiving unit overlaps with the first light-receiving unit in the transport direction and is spaced apart from the first light-receiving unit in the width direction.

2. The printing apparatus of claim 1, further comprising an output unit configured to amplify the difference between the output from the first light-receiving unit and the output from the second light-receiving unit, and to output the difference.

3. The printing apparatus of claim 2, further comprising an obtaining unit configured to obtain the end position of the printing medium in the width direction based on the output value of the output unit as the carriage moves in the width direction.

4. The printing apparatus according to claim 3, wherein, The obtaining unit obtains the output value from the output unit by taking the midpoint of the two points of the threshold as the end position.

5. The printing device according to claim 1, wherein, The first detection unit and the second detection unit, which include the light-emitting unit, the first light-receiving unit and the second light-receiving unit, further include at least one of the following: a third light-receiving unit, which is capable of receiving reflected light from the support unit and the printing medium supported on the support unit, and the third light-receiving unit is disposed between the first light-receiving unit and the second light-receiving unit in the width direction.

6. The printing apparatus of claim 5, further comprising an output unit configured to amplify and output the outputs from the first light-receiving unit, the second light-receiving unit, and the third light-receiving unit. in, The output unit includes: A first amplification unit is configured to amplify the difference between the output from the first light-receiving unit and the output from the second light-receiving unit, and The second amplification unit is configured to amplify the output from the third light-receiving unit and output the output.

7. The printing apparatus of claim 6, further comprising an obtaining unit configured to obtain the end position of the printing medium in the width direction based on an output value from the output unit as the carriage moves in the width direction. in, The obtaining unit: The output value from the first amplification unit is obtained at the midpoint between two points passing through the first threshold, as the end position. The point where the output value from the second amplification unit passes through the second threshold is obtained as the end position.

8. The printing apparatus of claim 1 or 2, further comprising a printing control unit configured to perform printing by alternately performing a first printing and a second printing, the first printing being printing in which ink is ejected from the printhead while the carriage is moved in a first direction from one side of the width direction to the other, and the second printing being printing in which ink is ejected from the printhead while the carriage is moved in a second direction from the other side of the width direction to one side. in, During the second printing, the first detection unit detects a first end located on one side of the printing medium in the width direction, and During the first printing, the second detection unit detects the second end located on the other side of the printing medium in the width direction.

9. The printing apparatus according to claim 8, further comprising: The obtaining unit is configured to obtain the position of the first end based on the detection result of the first detection unit, and to obtain the position of the second end based on the detection result of the second detection unit; as well as A determining unit is configured to determine the position of the first end obtained in the obtaining unit as the print start position when performing the immediately following first print, and to determine the position of the second end obtained in the obtaining unit as the print start position when performing the immediately following second print.

10. The printing apparatus according to claim 4, wherein, The obtaining unit sets two points corresponding to the output value from the output unit through the threshold as a pair, and obtains the midpoint of the pair of points through the threshold as the end position, wherein the distance between the pair of points is closest to a predetermined value.

11. The printing apparatus according to claim 4, wherein, The obtaining unit: The output values ​​from the output unit are passed through the threshold, and two points corresponding to each other are set as a pair. The output value from the output unit is obtained by taking the midpoint of a pair of points of the threshold as the end position, wherein the difference between the distance between the pair of points and a predetermined value is equal to or less than a first value.

12. The printing apparatus according to claim 10 or 11, wherein, The predetermined value is the distance between the first light-receiving unit and the second light-receiving unit in the width direction.

13. The printing apparatus according to claim 11, wherein, The first value is a predetermined proportion relative to the predetermined value.

14. The printing apparatus of claim 1, further comprising a changing unit configured to change the stop position of the carriage to a downstream position in the predetermined direction during printing by ejecting ink from the printhead while the carriage is moved in a predetermined direction from the other side of the width direction toward one side. in, The first detection unit includes: A light-emitting unit configured to emit light toward the support unit and the printing medium supported on the support unit; and The light-receiving unit is capable of receiving reflected light from the support unit and the printing medium supported on the support unit.

15. The printing apparatus according to claim 14, wherein, The changed stop position, obtained using the changing unit, is separated from the position corresponding to the end by a predetermined distance, and The predetermined distance is the distance from the start of deceleration of the carriage until the carriage stops, or a fixed amount longer than the distance from the start of deceleration of the carriage until the carriage stops.

16. The printing apparatus according to claim 15, wherein, The position corresponding to the end is obtained based on the detection result detected in the first detection unit in the immediate preceding operation.

17. The printing apparatus according to claim 1, wherein, The first detection unit includes: A light-emitting unit configured to emit light toward the support unit and the printing medium supported on the support unit; and A light-receiving unit, capable of receiving reflected light from the support unit and the printing medium supported on the support unit, and The printing device also includes: A receiving unit, configured to receive a point where the output from the light-receiving unit passes a threshold, as the end position of the printing medium on one side in the width direction; and A correction unit is configured to correct the end position obtained by the obtaining unit.

18. The printing apparatus according to claim 17, wherein, The correction unit determines the correction amount based on the difference between the reference speed and the moving speed of the carriage when the first detection unit passes the end.

19. The printing apparatus according to claim 18, wherein, The moving speed of the carriage as the first detection unit passes the end is obtained based on the printing conditions.

20. The printing apparatus of claim 19, further comprising a changing unit configured to change the stop position of the carriage to a downstream position in the predetermined direction during printing by ejecting ink from the printhead while the carriage is moved in a predetermined direction from the other side of the width direction toward one side. in, If the moving speed of the carriage is lower than a predetermined speed when the first detection unit passes the end, the changing unit changes the stopping position, and When the moving speed of the carriage is equal to or higher than the predetermined speed when the first detection unit passes the end, the correction unit corrects the position of the end.

21. The printing apparatus according to claim 4, wherein, The obtaining unit obtains the midpoint between two points that are corresponding to each other and whose output values ​​from the output unit pass through the threshold within the detection range used to detect the end position, as the end position.

22. The printing apparatus according to claim 4, wherein, The obtaining unit obtains the midpoint between the point where the output value from the output unit initially exceeds the threshold and the point where the output value from the output unit finally drops below the threshold within the detection range used to detect the end position, as the end position.

23. The printing apparatus according to claim 21 or 22, wherein, The detection range is set based on the delivery position and size of the printing medium, or based on the detection results of the delivered printing medium in the first detection unit or the second detection unit.

24. The printing apparatus according to claim 4, wherein, The obtaining unit: The first point where the output value from the output unit exceeds the threshold and the second point where the output value immediately following the first point drops below the threshold are set as corresponding responses, and If the distance between the two points in the corresponding pair is outside the set range, the second point is moved to a position separated from the first point by a predetermined value, and the midpoint between the first point and the moved second point is obtained as the end position.

25. The printing apparatus according to claim 4, wherein, The obtaining unit: The first point where the output value from the output unit exceeds the threshold and the second point where the output value immediately following the first point drops below the threshold are set as corresponding responses, and If the distance between the two points in the corresponding pair is outside the set range, the first point is moved to a position that is separated from the second point by a predetermined value, and the midpoint between the moved first point and the second point is obtained as the end position.

26. The printing apparatus according to claim 24 or 25, wherein, The setting range is a value corresponding to the distance between the first detection unit and the second detection unit in the width direction, and is a range in which the distance of the end position relative to the first point can be obtained.

27. The printing apparatus according to claim 24 or 25, wherein, The predetermined value is a distance from the end position that is obtained by spacing the second point from the first point based on the positional relationship between the first detection unit and the second detection unit.

28. A method for controlling a printing device, the printing device comprising: A support unit configured to support the delivered printing medium; A carriage in which a printhead is mounted, the printhead being configured to print by ejecting ink onto the printing medium, the carriage being movable in the width direction of the printing medium intersecting the transport direction of the printing medium; A first detection unit is disposed on one side of the carriage in the width direction and is capable of detecting the end of the printing medium in the width direction; as well as A second detection unit is disposed on the other side of the carriage in the width direction and is capable of detecting the end of the printing medium in the width direction. At least one of the first detection unit and the second detection unit includes: A light-emitting unit is configured to emit light toward the support unit and the printing medium supported on the support unit; A first light-receiving unit is capable of receiving reflected light from the support unit and the printing medium supported on the support unit; and A second light-receiving unit is capable of receiving reflected light from the support unit and the printing medium supported on the support unit. The second light-receiving unit overlaps with the first light-receiving unit in the transport direction and is spaced apart from the first light-receiving unit in the width direction. The control method includes: During the first print, the first detection unit detects a first end located on one side of the print medium in the width direction. In the first print, ink is ejected from the print head while the carriage moves in a direction from the other side of the width direction toward one side. During the second printing, the second detection unit detects the second end of the printing medium located on the other side of the width direction. In the second printing, ink is ejected from the print head while the carriage moves in a direction from one side of the width direction to the other side.

29. The control method according to claim 28, wherein, The position of the first end obtained based on the detection result of the first detection unit is set as the printing start position when performing the subsequent second printing, and the position of the second end obtained based on the detection result of the second detection unit is set as the printing start position when performing the subsequent first printing.

30. A computer-readable storage medium storing a program that causes a computer to perform the method according to claim 28.

31. A computer program product comprising a program that causes a computer to perform the method of claim 28.

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