JP2019018420A - Sheet end detection device, transport device, and image recorder - Google Patents

Abstract

To accurately detect positions of both ends of a sheet in a width direction.SOLUTION: A compound machine 10 comprises: a medium sensor 110 which radiates light toward a platen 42 which supports a sheet 12, and outputs an electric signal according to an amount of reflectance of said light; a carriage 23 which has the medium sensor 110, and reciprocatingly moves in a longitudinal direction 9; and a control part 130. The control part 130 causes the medium sensor 110 to radiate light of a first amount while moving the carriage 23 and acquires a first electric signal outputted from the medium sensor 110 (S50), causes the medium sensor 110 to radiate light of a second amount smaller than the first amount while moving the carriage 23 and acquires a second electric signal outputted from the medium sensor 110 (S40), calculates an average value of a maximum value of the first electric signal and a minimum value of the second electric signal and determines a position in the longitudinal direction 9 corresponding to said average value as an end of the sheet 12 in the longitudinal direction 9 which is supported by the platen 42 (S60).SELECTED DRAWING: Figure 8

Description

  The present invention relates to a sheet edge detection device that detects a sheet edge, a sheet conveyance device that includes a sheet edge detection device and conveys a sheet, and an image recording apparatus that includes a conveyance device and records an image on a sheet.

  The sheet edge detection device includes an optical sensor. The optical sensor is disposed to face the support portion that supports the sheet, and is disposed to be movable along the width direction. The optical sensor moves along the width direction while irradiating light while the sheet is supported by the support portion. The optical sensor receives reflected light reflected by the support portion and reflected light reflected by the sheet. At this time, the amount of reflected light reflected by the support portion is different from the amount of reflected light reflected by the sheet. Based on this difference, both end positions in the width direction of the sheet are detected.

  At this time, if the support portion is dirty, there may be a problem that the amount of reflected light reflected by the support portion varies. For example, in an ink jet recording apparatus that records an image on a sheet by ejecting ink from a nozzle, when so-called borderless printing is performed in which an image is recorded without providing a margin on the sheet, ink is applied to an outer area of the sheet. Discharged. The ejected ink adheres to and accumulates on the support portion, so that the support portion becomes dirty.

  In order to solve the above problem, in the devices disclosed in Patent Documents 1 to 3, the reflected light reflected by the support portion is detected in advance in a state where the sheet is not supported by the support portion. And in the said apparatus, the detection result of the reflected light reflected by the support part and the sheet | seat in the state in which the sheet | seat was supported by the support part is correct | amended based on the result of the said detection, or a threshold value is changed.

JP 2014-76613 A JP 2005-313603 A JP 2014-172388 A

  However, means for solving the above problems are not limited to the means employed in the devices disclosed in Patent Documents 1 to 3, and various means are conceivable. For example, the devices disclosed in Patent Documents 1 to 3 detect the reflected light reflected by the support part in a state where the sheet is not supported by the support part in advance. However, a means for solving the above-described problem can be considered without detecting the reflected light reflected by the support part in a state where the sheet is not supported by the support part in advance.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide means capable of accurately detecting both end positions in the width direction of a sheet.

  (1) A sheet end detection device according to the present invention is configured to face a support unit that supports a sheet, and to irradiate light toward the support unit, in accordance with the amount of reflected light of the light. A sensor that outputs an electrical signal; a carriage that includes the sensor, and that reciprocates in the width direction along the sheet support surface of the support portion; and a control portion. The control unit irradiates the sensor with a first light amount while moving the carriage in the width direction, and acquires a first electrical signal output from the sensor. The control unit irradiates the sensor with a second light amount smaller than the first light amount while moving the carriage in the width direction, and acquires a second electrical signal output from the sensor. The control unit calculates an average value of a first value based on a first range having a large signal value in the first electric signal and a second value based on a second range having a small signal value among the second electric signal. The position in the width direction corresponding to the average value is calculated and determined as the end in the width direction of the sheet supported by the support portion.

  When the sensor irradiates light while moving the carriage in the width direction in a state where the sheet is supported by the support portion, the electrical signal output from the sensor is the first range where the signal value is large and the first range where the signal value is small. It consists of roughly two ranges of two ranges. The first range is assumed to be a signal corresponding to the region where the sheet is located in the support portion. The second range is assumed to be a signal corresponding to an area where the sheet is not located in the support portion. In the first range, variations in signal values due to unevenness of the sheet surface can occur. In the second range, the signal value may vary due to dirt on the support portion.

  According to this configuration, by irradiating the sensor with the first light amount of light, which is a large amount of light, it is possible to saturate the signal value in the first range of the first electric signal and reduce the variation in the signal value. Further, by irradiating the sensor with a second light amount of light, which is a small amount of light, it is possible to reduce the variation in the signal value of the second range in the second electric signal. Then, by calculating the edge in the width direction of the sheet based on the first value of the first electric signal having a small variation and the second value of the second electric signal having a small variation, the both end positions in the width direction of the sheet are accurately determined. Can be detected.

  In addition, if the sheet edge detection device detects reflected light reflected by the support unit in a state where the sheet is not previously supported by the support unit, the sheet is supported by a sheet jam or the like after the prior detection. If the situation is not supported by the part, the prior detection becomes useless. On the other hand, in this configuration, it is possible to detect the sheet edge while the sheet is supported by the support portion, and therefore it is possible to prevent the above-described useless detection from being performed.

  (2) The control unit executes the acquisition of the second electric signal before the acquisition of the first electric signal.

  For example, when the user-specified size is B5 size but the sheet actually sent to the support unit is A4 size larger than B5 size, the second electric signal is sent first as in this configuration. In this case, it can be understood that the reason why the first range of the second electric signal is large is due to a sheet error. This is because in the second electric signal, the variation in the signal value in the second range can be reduced, so that the influence of the dirt on the support portion is difficult to occur. On the other hand, if the first electric signal is acquired first, it is difficult to determine whether the reason why the first range of the first electric signal is large is due to a sheet error or due to dirt on the support portion. is there. Therefore, it is difficult to make a correct determination until the second electrical signal is acquired thereafter. That is, the determination is slower than when the second electrical signal is acquired first.

  (3) In the sheet edge detection device according to the present invention, the sheet supported by the support portion is formed into a wave shape in which a plurality of convex portions approaching the sensor and a plurality of concave portions moving away from the sensor are alternately arranged in the width direction. A waveform forming mechanism is provided. The first light amount has a first difference between a value of the first electric signal corresponding to the reflected light reflected by the convex portion and a value of the first electric signal corresponding to the reflected light reflected by the concave portion. This is the amount of light.

  When the sheet is formed into a wave shape by the wave shape forming mechanism, the variation in the signal value in the first range (the signal corresponding to the region where the sheet is located in the support portion) increases. However, the variation can be reduced by the first light amount as in the present configuration.

  (4) The sheet end detection device according to the present invention includes a storage unit in which at least one of the first light amount or the second light amount corresponding to each of the types of sheets supported by the support unit and each of the types is stored. Prepare. The control unit refers to the storage unit and determines at least one of the first light amount and the second light amount based on the type of sheet supported by the support unit.

  When different types of sheets are irradiated with the same amount of light from the sensor, the electrical signal output by the sensor varies depending on the type of sheet. Therefore, by setting the amount of light emitted from the sensor based on the type of sheet as in this configuration, the electrical signal output from the sensor can be made constant regardless of the type of sheet.

  (5) For example, the first value is a maximum value in the first electric signal.

  (6) For example, the second value is a minimum value in the first electric signal.

  (7) The present invention can also be understood as a conveyance device including the sheet edge detection device and a conveyance unit that conveys the sheet. The control unit causes the conveyance unit to convey the sheet. The support unit supports the sheet conveyed by the conveyance unit.

  (8) The present invention provides a sheet end detection device, a conveyance unit that conveys a sheet, a sheet tray that supports a sheet fed toward the conveyance unit, and a sheet supported by the sheet tray. It can also be grasped as a transfer device provided with a positioning part that positions in the width direction with the central part in the width direction as a reference position. The control unit causes the conveyance unit to convey the sheet. The support unit supports the sheet conveyed by the conveyance unit. The first value of the first electric signal is an average value of signal values at a plurality of positions close to the reference position in the width direction.

  If the portion protruding from the first electric signal due to noise or the like is the first value, the first value of the first electric signal becomes extremely large. According to this configuration, the first value of the first electric signal is an average value of the signal values at a plurality of positions. Therefore, the possibility that the first value of the first electric signal becomes extremely large can be reduced.

  In the state where the sheet is supported by the support part, the sheet is always on the support part at a position close to the reference position in the width direction. According to this configuration, the first value of the first electric signal is calculated from the signal values at a plurality of positions close to the reference position in the width direction, that is, the signal value at the position where the sheet exists.

  (9) The present invention can also be understood as an image recording apparatus that includes the transport device and a recording head that is mounted on the carriage and ejects ink toward the support portion.

  (10) The second light amount corresponds to the value of the second electric signal corresponding to the light reflected at the position where the ink on the support portion is not deposited and the light reflected at the position where the ink can be deposited on the support portion. The difference from the value of the second electric signal is the amount of light that becomes the second difference value.

  When the ink is deposited on the support portion, the variation of the signal value in the second range becomes large at a large light amount such as the first light amount. However, the variation can be reduced by using the second light amount as in the present configuration.

  (11) The recording head ejects pigment ink.

  Pigment ink is easier to deposit on the support than dye ink. However, according to this configuration, as described above, the sheet edge can be accurately detected even when ink is deposited on the support portion.

  According to the present invention, both end positions in the width direction of the sheet can be accurately detected.

FIG. 1 is an external perspective view of the multifunction machine 10. FIG. 2 is a longitudinal sectional view schematically showing the internal structure of the printer unit 11. FIG. 3 is a perspective view of the feeding tray 20. FIG. 4 is a perspective view showing the recording unit 24, the platen 42, and the guide rails 43 and 44. FIG. 5 is a perspective view showing the contact member 80, the transport roller 60, the platen 42, and the discharge roller pair 55. FIG. 6 is a cross-sectional view showing the platen 42, the contact member 80, and the paper 12. FIG. 7 is a block diagram illustrating configurations of the control unit 130 and the storage unit 140. FIG. 8 is a flowchart for explaining detection control of the left and right end positions of the sheet 12. FIG. 9 is a characteristic diagram showing an electrical signal output from the media sensor 110 to the control unit 130.

  Hereinafter, embodiments of the present invention will be described. The embodiment described below is merely an example of the present invention, and it is needless to say that the embodiment of the present invention can be changed as appropriate without departing from the gist of the present invention. In the following description, the vertical direction 7 is defined based on the state in which the multifunction machine 10 is installed (the state shown in FIG. 1), and the front-rear direction 8 is defined with the surface on which the opening 13 is formed as the front surface. The left-right direction 9 (an example of the width direction) is defined when the multifunction device 10 is viewed from the front. In the present embodiment, in a state where the multifunction machine 10 is installed to be usable, the vertical direction 7 corresponds to the vertical direction, and the front-rear direction 8 and the horizontal direction 9 correspond to the horizontal direction. The front-rear direction 8 and the left-right direction 9 are orthogonal to each other.

[Overall configuration of MFP 10]
As shown in FIG. 1, the multifunction machine 10 is generally formed in a rectangular parallelepiped. The multifunction machine 10 includes a printer unit 11 (an example of an image recording apparatus) that records an image on a sheet 12 (an example of a sheet, see FIG. 2) using an inkjet recording method at the bottom. The multifunction machine 10 has various functions such as a facsimile function and a print function.

  As shown in FIG. 2, the printer unit 11 includes a recording head 39 and a transport device. The conveyance device includes a feeding tray 20 (an example of a sheet tray), a discharge tray 21, a positioning unit 90 (see FIG. 3), a feeding unit 15, a conveyance roller pair 54 (an example of a conveyance unit), and a discharge. A roller pair 55 and a sheet end detection device are provided. The sheet edge detection device includes a platen 42 (an example of a support unit), a media sensor 110 (an example of a sensor), a carriage 23, a control unit 130 (see FIG. 7), and a storage unit 140 (see FIG. 7). Prepare.

[Feeding tray 20]
As shown in FIG. 1, the printer unit 11 includes an opening 13 on the front surface. The feeding tray 20 can be inserted and removed from the opening 13 in the front-rear direction 8. The feeding tray 20 can support various sizes of paper 12.

  As shown in FIG. 3, the feeding tray 20 has a box shape with the top opened. The feeding tray 20 includes a bottom plate 32. The bottom plate 32 can support a plurality of standard size sheets 12 such as A4 size, B5 size, legal size, and postcard size. The bottom plate 32 is provided with a mark indicating the position of one side end (left end in the example of FIG. 3) in the left-right direction 9 of the paper 12 of various standard sizes. In FIG. 3, two types of “A4” and “B5” are shown as examples of the mark, but the mark is not limited to these.

[Discharge tray 21]
As shown in FIG. 1, the discharge tray 21 is located above the feeding tray 20. The discharge tray 21 supports the paper 12 on which an image is recorded by the recording unit 24 and discharged.

[Positioning part 90]
As shown in FIG. 3, the positioning portion 90 is disposed on the bottom plate 32. The positioning unit 90 positions both ends of the sheet 12 supported by the bottom plate 32 in the left-right direction 9. The positioning unit 90 positions the sheets 12 of various fixed sizes supported by the bottom plate 32 by centering. Thereby, the skew of the paper 12 is suppressed. The center alignment means alignment that aligns the center of the sheet 12 in the left-right direction 9 with the center of the bottom plate 32 in the left-right direction 9. That is, the center alignment means alignment in which the paper 12 is positioned in the left-right direction 9 with the center in the left-right direction 9 as a reference position.

  The positioning unit 90 includes a pair of guide members 91 and 92 and a pinion gear 93. The pair of guide members 91 and 92 are disposed to face the left-right direction 9. The pair of guide members 91 and 92 are supported by the bottom plate 32 so as to be slidable in the left-right direction 9. The pinion gear 93 moves the pair of guide members 91 and 92 in conjunction with each other. The pinion gear 93 is arranged at the center of the bottom plate 32 in the left-right direction 9 with the central axis line along the up-down direction 7.

  The guide member 91 is disposed to the right of a center line (a line indicated by a one-dot chain line in FIG. 3) extending in the front-rear direction 8 in the center of the bottom plate 32. The guide member 91 includes a support plate 94, side plates 95, and a rack gear 96. The support plate 94 is supported by the bottom plate 32. The side plate 95 protrudes upward from the right end portion of the support plate 94. The rack gear 96 extends leftward from the support plate 94. The rack gear 96 meshes with the pinion gear 93 in front of the pinion gear 93.

  The guide member 92 is disposed to the left of the center line. The guide member 92 includes a support plate 97, a side plate 98, and a rack gear 99. The guide member 92 has a shape that is substantially symmetrical to the guide member 91. The support plate 97 is supported by the bottom plate 32. The side plate 98 protrudes upward from the left end portion of the support plate 97. The rack gear 99 extends rightward from the support plate 97. The rack gear 99 meshes with the pinion gear 93 behind the pinion gear 93.

  The user places the paper 12 between the guide members 91 and 92 on the bottom plate 32. Next, the user moves one of the guide members 91 and 92 so as to contact the right end or the left end of the sheet 12. The other of the guide members 91 and 92 is interlocked with the movement of one of the guide members 91 and 92 via the pinion gear 93. It moves so as to touch the left end or the right end of the paper 12. As a result, the support plate 94 sinks under the right end portion of the sheet 12, and the support plate 97 sinks under the left end portion of the sheet 12. Further, the side plate 95 contacts the right end of the paper 12, and the side plate 98 contacts the left end of the paper 12. In this way, the sheets 12 of various standard sizes supported by the bottom plate 32 are positioned in the left-right direction 9 by centering by the positioning unit 90.

[Feeding unit 15]
As shown in FIG. 2, the feeding unit 15 is disposed above the bottom plate 32 of the feeding tray 20 that is inserted into the printer unit 11. The feeding unit 15 includes a feeding roller 25, a feeding arm 26, and a shaft 27.

  The feed roller 25 is rotatably supported at the distal end portion of the feed arm 26. The feeding roller 25 rotates with a driving force applied from a feeding motor 101 (see FIG. 7). The feeding roller 25 may be rotated by applying a driving force from a conveyance motor 102 described later.

  A proximal end portion of the feeding arm 26 is rotatably supported on the shaft 27. The shaft 27 is supported by the frame of the printer unit 11. The feeding arm 26 is urged to rotate toward the bottom plate 32 by its own weight or an elastic force of a spring or the like. The feed roller 25 rotates while being in contact with the paper 12 supported by the bottom plate 32, thereby picking up the paper 12 supported by the bottom plate 32 and feeding it to a conveyance path 65 described later.

[Conveyance path 65]
As shown in FIG. 2, the conveyance path 65 indicates a space defined by the outer guide member 18 and the inner guide member 19 that face each other at a predetermined interval in the printer unit 11. The conveyance path 65 is a path that extends rearward from the rear end portion of the feed tray 20, makes a U-turn while extending upward from below at the rear portion of the printer unit 11, and reaches the discharge tray 21 through the recording unit 24. The conveyance path 65 communicates with the discharge tray 21 through a nipping position by the conveyance roller pair 54, a position between the recording unit 24 and the platen 42, and a nipping position by the discharge roller pair 55. Note that the conveyance direction 16 of the paper 12 in the conveyance path 65 is indicated by a one-dot chain line arrow in FIG.

[Conveying roller pair 54 and discharging roller pair 55]
As shown in FIG. 2, the conveyance roller pair 54 is disposed in the conveyance path 65. The conveyance roller pair 54 includes a conveyance roller 60 and a pinch roller 61. The discharge roller pair 55 is disposed downstream of the conveyance roller pair 54 in the conveyance path 65. The discharge roller pair 55 includes a discharge roller 62 and a spur 63.

  The conveyance roller 60 and the pinch roller 61 are in contact with each other. The discharge roller 62 and the spur 63 are in contact with each other. The conveyance roller 60 and the discharge roller 62 are rotated by a driving force transmitted from the conveyance motor 102 (see FIG. 7). As a result, the transport roller pair 54 and the discharge roller pair 55 sandwich the paper 12 and transport it in the transport direction 16.

[Platen 42]
As shown in FIG. 2, the platen 42 is disposed between the conveyance roller pair 54 and the discharge roller pair 55 in the conveyance path 65. The platen 42 is disposed to face the recording unit 24 in the vertical direction 7. The platen 42 supports the paper 12 conveyed through the conveyance path 65 from below.

  As shown in FIGS. 4 and 5, a plurality of support ribs 52 projecting upward are formed on the upper surface of the platen 42. Each support rib 52 extends in the front-rear direction 8 at least at a position facing the nozzle 40 (see FIG. 2) of the recording unit 24. The support ribs 52 are arranged at intervals in the left-right direction 9. The sheet 12 conveyed through the conveyance path 65 is supported by the platen 42, specifically, the upper surfaces of a plurality of support ribs 52 formed on the platen 42. A virtual surface (an example of a sheet support surface) including the upper surfaces of the plurality of support ribs 52 is a surface that extends in the front-rear direction 8 and the left-right direction 9.

[Recording unit 24]
As shown in FIG. 2, the recording unit 24 is disposed between the conveyance roller pair 54 and the discharge roller pair 55 in the conveyance path 65. The recording unit 24 is disposed at a position facing the platen 42 above the conveyance path 65. The recording unit 24 includes a carriage 23 and a recording head 39. The carriage 23 is disposed at a position facing the platen 42 above the conveyance path 65. The carriage 23 reciprocates in the scanning direction (left-right direction 9) orthogonal to the transport direction 16.

  As shown in FIG. 4, the carriage 23 is supported by guide rails 43 and 44 that are arranged at an interval in the front-rear direction 8 of the platen 42. A known belt mechanism (not shown) is provided on at least one of the guide rails 43 and 44. The carriage 23 is connected to a belt mechanism. The belt mechanism is driven by a carriage driving motor 103 (see FIG. 7). Thereby, the carriage 23 can reciprocate in the left-right direction 9.

  As shown in FIG. 2, the recording head 39 is mounted on the carriage 23. A plurality of nozzles 40 are formed on the lower surface of the recording head 39 (the surface facing the platen 42). Ink is supplied to the recording head 39 from an ink cartridge (not shown). In the present embodiment, the ink supplied from the ink cartridge to the recording head 39 is a pigment. The recording head 39 ejects ink from the nozzle 40 as fine ink droplets. When the carriage 23 reciprocates in the left-right direction 9, ink droplets are ejected from the nozzle 40 toward the platen 42. As a result, ink droplets land on the paper 12 supported by the platen 42 and an image is recorded on the paper 12.

[Media sensor 110]
As shown in FIG. 2, a media sensor 110 that is used to detect the paper 12 that is conveyed along the conveyance path 65 is mounted on the carriage 23. The media sensor 110 is arranged on the lower surface of the carriage 23 upstream of the nozzle 40 in the transport direction 16. In the transport direction 16, at least a part of the media sensor 100 may be disposed so as to overlap the nozzle 40.

  The media sensor 110 includes a light emitting unit 111 (see FIG. 7) made of a light emitting diode or the like, and a light receiving unit 112 (see FIG. 7) made of an optical sensor or the like. The light emitting unit 111 irradiates light toward the detection region 100 of the platen 42 shown in FIG. 5 with a light amount instructed by a control unit 130 (see FIG. 7) described later. The light irradiated to the detection region 100 is reflected on the platen 42 or the paper 12 supported by the platen 42. The reflected light is received by the light receiving unit 112. The media sensor 110 outputs an electrical signal corresponding to the amount of reflected light received by the light receiving unit 112 to the control unit 130. For example, the media sensor 110 outputs an electrical signal having a higher level to the control unit 130 as the received light amount is larger.

[Abutting member 80]
As shown in FIGS. 2, 4, and 5, a plurality of contact members 80 are provided upstream of the nozzle 40 in the transport path 65 in the transport direction 16. In the present embodiment, as shown in FIG. 5, nine contact members 80 are provided. The number of contact members 80 is not limited to nine. As shown in FIGS. 2 and 5, each contact member 80 includes an attachment portion 81, a bending portion 82, and a contact portion 83.

  The attachment portion 81 has a generally flat plate shape. Each attachment portion 81 is attached to the guide rail 43. As shown in FIG. 5, a plurality (four in the present embodiment) of hooks 75 protrude upward on the upper surface of each mounting part 81. The hook portion 75 is bent backward at the upper end portion. On the other hand, as shown in FIG. 4, the guide rail 43 includes a plurality of openings 74. Each hook 75 is inserted through the corresponding opening 74 and locked. Thereby, the upper surface of each attachment part 81 is attached to the lower surface of the guide rail 43. Further, the attachment portions 81 are attached to be separated from each other in the left-right direction 9.

  As shown in FIGS. 2, 4, and 5, the bending portion 82 protrudes forward from the attachment portion 81 (downstream of the conveyance direction 16 in a state where the contact member 80 is attached to the guide rail 43). doing. The curved portion 82 is curved downward while extending forward. A contact portion 83 protrudes forward from the front end portion of the bending portion 82, that is, the front end portion.

  The abutting portion 83 has a generally flat plate shape. The abutting portion 83 is positioned upstream in the transport direction 16 with respect to the nozzle 40 of the recording head 39. The abutting portion 83 faces the platen 42 in the vertical direction 7. The sheet 12 is conveyed between the lower surface 84 (see FIG. 6) of the contact portion 83 and the platen 42.

  As shown in FIG. 6, the lower surface 84 of the contact portion 83 is provided with a contact rib 85 that protrudes downward. The lower end of the contact rib 85 is in contact with the image recording surface of the paper 12 supported by the platen 42, that is, the upper surface of the paper 12. As a result, the sheet 12 is pressed downward (that is, the platen 42) by the contact portion 83.

  As shown in FIG. 5, the support ribs 52 formed on the platen 42 are formed at positions where the contact portions 83 are not arranged in the left-right direction 9. That is, the contact portion 83 and the support rib 52 are not opposed to each other.

  As shown in FIG. 6, each support rib 52 protrudes above the lower end of the contact rib 85 of each contact portion 83. That is, the upper end of the platen 42 is located above the lower end of the contact portion 83. As described above, the sheet 12 supported by the platen 42 is in a wavy state when viewed in the front-rear direction 8 between the platen 42 and the contact portion 83. In other words, the sheet 12 has an abutment member 80 and a support rib 52 that alternately protrude upwardly in a direction approaching the lower surface of the carriage 23, and recessed portion 12 </ b> B away from the lower surface of the carriage 23 in the left-right direction 9. A plurality of wave shapes are arranged. The contact member 80 and the support rib 52 are an example of a wave shape forming mechanism.

[Control unit 130 and storage unit 140]
Hereinafter, the configuration of the control unit 130 and the storage unit 140 will be described with reference to FIG. 7. The control unit 130 performs detection control according to a flowchart (see FIG. 8) described later, thereby realizing the present invention.

  As shown in FIG. 7, the control unit 130 includes a CPU 131 and an ASIC 135. The storage unit 140 includes a ROM 132, a RAM 133, and an EEPROM 134. The CPU 131, the ASIC 135, the ROM 132, the RAM 133, and the EEPROM 134 are connected by an internal bus 137.

  The ROM 132 stores a program for the CPU 131 to control various operations. The RAM 133 is used as a storage area for temporarily recording data and signals used when the CPU 131 executes the program, or as a work area for data processing. The EEPROM 134 stores settings, flags, and the like that should be retained even after the power is turned off.

  Connected to the ASIC 135 are a feeding motor 101, a conveying motor 102, and a carriage driving motor 103. The ASIC 135 incorporates a drive circuit that controls each motor. The CPU 131 outputs a drive signal for rotating each motor to a drive circuit (not shown) corresponding to each motor. The drive circuit outputs a drive current corresponding to the drive signal acquired from the CPU 131 to the corresponding motor. As a result, the corresponding motor rotates. That is, the control unit 130 controls the feeding motor 101 to cause the feeding unit 15 to feed the paper 12. Further, the control unit 130 controls the transport motor 102 to transport the paper 12 to the transport roller pair 54 and the discharge roller pair 55. The control unit 130 controls the carriage driving motor 103 to move the carriage 23.

  The media sensor 110 is connected to the ASIC 135. The control unit 130 outputs various electrical signals to the media sensor 110 through the ASIC 135. The light emitting unit 111 emits light of a light amount corresponding to the level of the electrical signal output from the control unit 130 downward. The light receiving unit 112 receives light reflected from the platen 42 or the paper 12 by the light emitted from the light emitting unit 111. The media sensor 110 outputs an electrical signal having a level corresponding to the amount of reflected light received by the light receiving unit 112 to the control unit 130. The control unit 130 recognizes the amount of reflected light received based on the level of the electrical signal acquired from the media sensor 110.

[Detection control of left and right end positions of paper 12]
Hereinafter, detection control of the left and right end positions of the paper 12 by the control unit 130 will be described based on the flowchart of FIG. The detection control is control for detecting both end positions in the left-right direction 9 of the sheet 12 supported by the platen 42.

  The detection control is started when an instruction to print on the paper 12 is sent to the control unit 130 from the operation unit 17 (see FIG. 1) of the multifunction device 10 or an external device connected to the multifunction device 10.

  When the detection control is started, the control unit 130 drives the feeding motor 101. As a result, the feed roller 25 rotates and the paper 12 supported by the feed tray 20 is fed to the transport path 65 (S10).

  When the sheet 12 fed in step S10 reaches the arrangement position of the conveyance roller pair 54, the control unit 130 drives the conveyance motor 102. As a result, the transport roller 60 and the discharge roller 62 rotate, and the paper 12 is transported in the transport direction 16 to the position where the paper 12 can face the media sensor 110 by the transport roller pair 54 (S20).

  The fact that the sheet 12 fed in step S10 has reached the arrangement position of the conveying roller pair 54 is, for example, counted time from the start of driving of the feeding motor 101, or the feeding motor 101 or feeding roller. The amount of rotation of 25 is recognized by being counted by a rotary encoder (not shown).

  Next, the control unit 130 drives the carriage driving motor 103 to move the carriage 23 to the paper detection start position (S30). The sheet detection start position is a position outside (right or left) of the sheet 12 supported by the platen 42 in the left-right direction 9. In the present embodiment, it is assumed that the paper detection start position is a position on the right side of the paper 12 supported by the platen 42.

  The control unit 130 can know the approximate size of the paper 12 by specifying the size of the paper 12 such as A4 or B5 by the operation of the operation unit 17 by the user. The paper detection start position can be determined based on the approximate size. Moreover, the process of step S30 may be performed in parallel with the processes of steps S10 and S20. Further, the process of step S30 can be omitted when the carriage 23 is originally located at the paper detection start position.

  Next, the control part 130 performs the small electrical signal acquisition process explained in full detail below (S40). In step S <b> 40, the control unit 130 drives the carriage driving motor 103 to move the carriage 23 from the paper detection start position (a position on the right side of the paper 12 supported by the platen 42) to the paper 12. Move to the left position. In addition, the control unit 130 outputs an electrical signal of a predetermined level to the media sensor 110 in parallel with the movement of the carriage 23. As a result, the light emitting unit 111 of the media sensor 110 emits light of a light amount (an example of a second light amount, hereinafter referred to as a second light amount) corresponding to a predetermined level downward. The control unit 130 acquires an electrical signal (an example of a second electrical signal) from the light receiving unit 112 corresponding to the amount of reflected light received with respect to the second light amount. An example of a signal acquired by the control unit 130 in the small electrical signal acquisition process (S40) is shown by a broken line in FIG.

  Next, the control part 130 performs the large electrical signal acquisition process explained in full detail below (S50). In step S50, the control unit 130 drives the carriage driving motor 103 to move the carriage 23 from the movement end position of the carriage 23 in step S40 (a position to the left of the paper 12 supported by the platen 42). It is moved to a position on the right side of the paper 12. Further, in parallel with the movement of the carriage 23, the control unit 130 outputs an electric signal having a level larger than the predetermined level in step S40 to the media sensor 110. Thereby, the light emitting unit 111 of the media sensor 110 emits light of a light amount (an example of a first light amount, hereinafter referred to as a first light amount) corresponding to the large level downward. The control unit 130 acquires an electrical signal (an example of a first electrical signal) from the light receiving unit 112 corresponding to the amount of reflected light received with respect to the first light amount. An example of the signal acquired by the control unit 130 in the large electrical signal acquisition process (S50) is shown by a solid line in FIG.

  Here, as shown in FIG. 9A, the electrical signals acquired in steps S40 and S50 have approximately two ranges, a first range RA1 having a large signal value and a second range RA2 having a small signal value. ing. As described above, the control unit 130 can know the approximate size of the paper 12 by specifying the size of the paper 12 such as A4 or B5 by the operation of the operation unit 17 by the user. Thus, the first range RA1 is assumed to be a signal corresponding to an area where the paper 12 is located on the platen 42. The second range RA2 is assumed to be a signal corresponding to an area in the platen 42 where the paper 12 is not located. That is, the control unit 130 determines the first range RA1 and the second range RA2 by specifying the size of the paper 12 by the operation of the user operation unit 17 or the like.

  Next, the control unit 130 executes a paper edge determination process described in detail below (S60). The control unit 130 calculates an average value AVG between the minimum value MIN (an example of the second value) of the electrical signal acquired in step S40 and the maximum value MAX (an example of the first value) of the electrical signal acquired in step S50. To do. The minimum value MIN is a value based on the second range RA2, and the maximum value MAX is a value based on the first range RA1. Then, the positions P1 and P2 at which the electrical signals acquired in step S50 take the average value AVG are determined as the positions in the right and left direction 9 of the right end and the left end of the paper 12 supported by the platen 42. Note that the position at which the electrical signal acquired in step S40 takes the average value AVG may be determined as the right and left positions 9 of the right and left ends of the paper 12 supported by the platen 42.

  The first light amount of light emitted from the light emitting unit 111 in the large electrical signal acquisition process (S50) is the value of the electrical signal corresponding to the reflected light reflected by the convex portion 12A of the paper 12 supported by the platen 42, and the platen. The difference from the value of the electrical signal corresponding to the reflected light reflected by the concave portion 12B of the paper 12 supported by 42 is set to a light amount larger than the light amount that becomes the first predetermined value (an example of the first difference value). .

  The first light quantity is set in advance (for example, before the multifunction machine 10 is shipped from the factory). Hereinafter, an example of setting the first light amount will be described. In a state where the paper 12 is supported on the platen 42, a process of irradiating light from the light emitting unit 111 while moving the carriage 23 in the left-right direction 9 is executed. This process is executed a plurality of times while increasing the amount of light emitted from the light emitting unit 111. In each of the processes executed a plurality of times, the control unit 130 determines the signal level at the convex portion 12A of the acquired electrical signal (the position of the support rib 52 in the left-right direction 9) and the concave portion 12B of the acquired electrical signal ( The difference value from the signal level at the position of the contact rib 80 of the contact member 80 in the left-right direction 9 is obtained. The difference value decreases as the amount of light emitted from the light emitting unit 111 increases. Then, the light amount emitted from the light emitting unit 111 when the difference value that has become smaller becomes the first predetermined value is set to the first light amount emitted from the light emitting unit 111 in step S50. The first predetermined value is set to the smallest possible value (ideally zero).

  When the first light quantity is small, the influence of the waveform of the paper 12 is greatly exerted on the electrical signal acquired in step S50. Therefore, the first predetermined value for setting the first light quantity is set to a value that reduces the influence. Therefore, as described above, the first predetermined value is preferably as small as possible (ideally zero).

  In the small electrical signal acquisition process (S40), the second light amount of light emitted from the light emitting unit 111 is the value of the electrical signal corresponding to the light reflected at the position where the ink on the platen 42 is not deposited and the ink on the platen 42 is deposited. The difference from the value of the electrical signal corresponding to the light reflected at the position where it can be performed is set to a light amount smaller than the light amount that becomes the second predetermined value (an example of the second difference value).

  A position where the ink is not deposited on the platen 42 (hereinafter referred to as a non-deposition position) is located immediately below the sheet 12 when the recording unit 24 performs so-called borderless printing in which ink droplets are ejected to the end of the sheet 12. Position.

  The position where the ink can be deposited on the platen 42 (hereinafter referred to as a deposition position) is a position that is outside the sheet 12 and immediately below a region near the edge of the sheet 12 when borderless printing is performed. It is.

  The second light quantity is set in advance (for example, before the multifunction machine 10 is shipped from the factory). Hereinafter, an example of setting the second light amount will be described. In a state in which the sheet 12 is not supported on the platen 42, a process of irradiating light from the light emitting unit 111 while moving the carriage 23 in the left-right direction 9 is executed. This process is executed a plurality of times while reducing the amount of light emitted from the light emitting unit 111. In each of the processes executed a plurality of times, the control unit 130 obtains a difference value between the signal level at the deposition position of the acquired electrical signal and the signal level at the non-deposition position of the acquired electrical signal. The difference value decreases as the amount of light emitted from the light emitting unit 111 decreases. Then, the light amount emitted from the light emitting unit 111 when the difference value that has become smaller becomes the second predetermined value is set to the second light amount emitted from the light emitting unit 111 in step S40. The second predetermined value is set to the smallest possible value (ideally zero).

  When the second light quantity is large (for example, when the light quantity is the same as the first light quantity), the electrical signal acquired in step S40 is greatly influenced by the ink deposited on the platen 42. Therefore, the second predetermined value for setting the second light quantity is set to a value that reduces the influence. Therefore, as described above, the second predetermined value is preferably as small as possible (ideally zero).

[Effect of this embodiment]
In a state where the paper 12 is supported by the platen 42, when the media sensor 110 emits light while moving the carriage 23 in the left-right direction 9, an electrical signal output from the media sensor 110 is a first signal having a large signal value. There are roughly two ranges, a range RA1 and a second range RA2 having a small signal value. In the first range RA1, variations in signal values due to irregularities on the surface of the paper 12 may occur. In the second range RA2, variations in signal values due to contamination of the platen 42 can occur.

  According to the present embodiment, by irradiating the media sensor 110 with a first light amount that is a large amount of light (S50), the signal value of the first range RA1 in the electrical signal indicated by the solid line in FIG. 9A. Can be saturated to reduce variations in signal values. Further, by irradiating the media sensor 110 with a second light amount that is a small amount of light (S40), variation in the signal value of the second range RA2 in the electrical signal indicated by the broken line in FIG. 9A is reduced. be able to. Then, the maximum value MAX of the electric signal indicated by a solid line in FIG. 9A with a small variation in the first range RA1, and the electric signal indicated by a broken line in FIG. 9A with a small variation in the second range RA2. By calculating the edge of the sheet 12 in the left-right direction 9 based on the minimum value MIN of the sheet 12 (S60), both end positions P1, P2 of the sheet 12 in the left-right direction 9 can be accurately detected.

  Also, if the sheet end detection device detects reflected light reflected by the platen 42 in a state where the sheet 12 is not supported on the platen 42 in advance, the sheet 12 is detected due to a paper jam after the prior detection. Is not supported by the platen 42, the prior detection becomes useless. On the other hand, in the present embodiment, it is possible to detect the end of the sheet while the sheet 12 is supported by the platen 42, and thus it is possible to prevent the above-described useless detection from being performed.

  For example, in the case where the sheet 12 actually sent to the platen 42 is an A4 size larger than the B5 size even though the user-specified size is the B5 size, a small electrical signal is acquired as in this embodiment. When the process is executed prior to the large electrical signal acquisition process (step S40 is performed prior to step S50) and the electrical signal indicated by the broken line in FIG. It can be seen that the reason why the one range RA1 is large is due to an error in the sheet 12. This is because the electrical signal indicated by the broken line in FIG. 9A can reduce the variation in the signal value in the second range RA2, and thus is less susceptible to contamination of the platen 42. On the other hand, when the large electrical signal acquisition process is executed prior to the small electrical signal acquisition process (step S50 is executed before step S40), the electrical signal indicated by the solid line in FIG. 9A is acquired first. It is difficult to determine whether the reason why the first range RA1 of the electric signal is large is due to an error in the paper 12 or due to contamination of the platen 42. Therefore, after that, it is difficult to make a correct determination until the electric signal indicated by the broken line in FIG. 9A is acquired in the small electric signal acquisition process. That is, the determination is slower than when the electrical signal indicated by the broken line in FIG.

  When the paper 12 is waved by the contact member 80 and the support rib 52, the variation in the signal value of the first range RA1 (a signal corresponding to the region where the paper 12 is located in the platen 42) increases. However, in the present embodiment, the first light amount is the value of the electrical signal corresponding to the reflected light reflected by the convex portion 12A of the paper 12 supported by the platen 42 and the concave portion 12B of the paper 12 supported by the platen 42. The difference between the value of the electric signal corresponding to the reflected light and the reflected light is set to a light amount that becomes the first predetermined value. Thereby, the variation can be reduced.

  When ink is deposited on the platen 42, the signal value variation in the second range RA2 becomes large at a large light amount such as the first light amount. However, in the present embodiment, the second light quantity corresponds to the value of the electrical signal corresponding to the light reflected at the position where the ink on the platen 42 is not deposited and the electricity corresponding to the light reflected at the position where the ink can be deposited on the platen 42. The difference between the signal value and the signal value is set to a second predetermined value. Thereby, the variation can be reduced.

  In the present embodiment, the pigment ink ejected from the recording head 39 is more easily deposited on the platen 42 than the dye ink. However, according to the present embodiment, as described above, even when ink is deposited on the platen 42, it is possible to accurately detect the sheet edge.

[Modification]
Information composed of the type of paper 12 supported by the platen 42 and at least one of the first light amount and the second light amount corresponding to each of the types is stored as a data table in the ROM 132, RAM 133, or EEPROM 134. It may be. Here, the type of the paper 12 is, for example, glossy paper or plain paper.

  For example, the type of the paper 12 is set when the user of the multifunction device 10 operates the operation unit 17 (see FIG. 1) of the multifunction device 10 when the paper 12 is supported on the feeding tray 20. For example, the type of the paper 12 may be determined by scanning the paper 12 supported on the platen 42 by the media sensor 110. In this case, the type of the paper 12 is determined based on the level of the electric signal output from the light receiving unit 112 to the control unit 130 in the scanning. For example, if the level of the electrical signal is high, the type of the paper 12 is determined as glossy paper, and if the level of the electrical signal is low, the type of the paper 12 is determined as plain paper.

  When the second light quantity is stored in the data table, the control unit 130 refers to the data table in the detection control step S40 (small electrical signal acquisition process), and sets the second light amount according to the set type of the paper 12. The light emitting unit 111 is irradiated with two amounts of light. Further, when the first light quantity is stored in the data table, the control unit 130 refers to the data table in step S50 (large electric signal acquisition process) of the detection control and corresponds to the set type of the paper 12. The light emitting unit 111 is irradiated with the first light amount.

  When different types of paper 12 are irradiated with the same amount of light from the media sensor 110, the electrical signal output by the media sensor 110 differs depending on the type of the paper 12. Therefore, as in this modification, the amount of light emitted from the media sensor 110 is set based on the type of the paper 12, so that the electrical signal output from the media sensor 110 can be made constant regardless of the type of the paper 12. it can.

  In the above embodiment, the first value is the maximum value MAX of the electrical signal acquired in step S50. In this case, in the electrical signal illustrated in FIG. 9B, the first value is A corresponding to the position P3. However, the first value is not limited to the maximum value MAX on condition that the first value is a value based on the first range RA1 among the electrical signals acquired in step S50.

  For example, the first value may be an average value of signal values at a plurality of positions, for example, three positions, close to the reference position in the left-right direction 9 (in this modification, the center in the left-right direction 9 as in the above embodiment). In this case, the first value is calculated as an average value of three values respectively corresponding to the positions P4, P5, and P6 in the electrical signal illustrated in FIG. 9B. In this example, the position P4 is a reference position, the position P5 is a position a predetermined distance to the right from the position P4, and the position P6 is a position a predetermined distance from the position P4 to the left.

  The plurality of positions may be determined irrespective of the reference position. For example, the plurality of positions may be determined from arbitrary positions within the first range RA1 of the electrical signal. Of course, the position in the first range RA1 may be the center in the left-right direction 9 or the end in the left-right direction 9.

  If the first value is the maximum value of the electric signal, if the electric signal has a protruding portion due to noise or the like, the first value of the electric signal becomes extremely large as shown by A in FIG. 9B. growing. According to this modification, the first value of the electrical signal is an average value of the signal values at a plurality of positions. Therefore, the possibility that the first value of the electrical signal becomes extremely large can be reduced.

  In the state where the paper 12 is supported by the platen 42, the paper 12 is always on the platen 42 at a position close to the reference position in the left-right direction 9 (position within the first range RA1). According to this modification, the first value of the electric signal is a signal value at a plurality of positions close to the reference position (position within the first range RA1) in the left-right direction 9, that is, a signal value at a position where the paper 12 is present. Is calculated from

  The second value is not limited to the minimum value MIN. For example, the second value is the position where the lowering stops when the level of the electric signal decreases from the level in the first range RA1 from the center in the left-right direction 9 of the first range RA1 toward the right or left. Also good. The position of the lowering stop is determined, for example, as follows. The difference between the levels of the electrical signals at two positions adjacent in the left-right direction 9 at predetermined intervals is sequentially calculated so that the center of the first range RA1 starts from the center of the first range RA1. Then, it is determined that the level starts to decrease from a position where the difference is equal to or greater than the first threshold value set in advance, and then the difference is equal to or less than the second threshold value (smaller than the first threshold value) set in advance. Judge that the level has stopped dropping at the position.

  In the embodiment described above, the control unit 130 determines the first range RA1 and the second range RA2 by specifying the size of the paper 12 by operating the operation unit 17 of the user. However, the means for determining the first range RA1 and the second range RA2 is not limited to this. For example, the control unit 130 may determine a signal having a level smaller than the small electrical signal threshold TH1 as the second range RA2. Further, the control unit 130 may determine a signal having a level larger than the large electrical signal threshold value TH2 as the first range RA1.

  The small electric signal threshold value TH1 and the large electric signal threshold value TH2 are values set in advance before the multifunction machine 10 is shipped from the factory. Hereinafter, an example of setting the small electrical signal threshold TH1 will be described. In a state where the paper 12 is supported by the platen 42, a process of irradiating the second light amount from the light emitting unit 111 while moving the carriage 23 in the left-right direction 9 is executed. Then, a value slightly larger than the signal level at the position where there is no paper 12 in the electrical signal acquired in the processing is set as the small electrical signal threshold TH1. Next, an example of setting the large electrical signal threshold value TH2 will be described. With the sheet 12 supported by the platen 42, a process of irradiating the first light amount from the light emitting unit 111 while moving the carriage 23 in the left-right direction 9 is executed. Then, a value slightly smaller than the signal level at the position where the paper 12 is present in the electrical signal acquired in the processing is set as the large electrical signal threshold TH2. The small electrical signal threshold value TH1 and the large electrical signal threshold value TH2 may be calculated by known means other than those described above.

  In the above-described embodiment, the small electrical signal acquisition process is performed before the large electrical signal acquisition process, but the large electrical signal acquisition process may be performed before the small electrical signal acquisition process.

  In the above embodiment, the ink supplied from the ink cartridge to the recording head 39 is a pigment. However, the ink supplied from the ink cartridge to the recording head 39 may be a dye instead of a pigment. The printer unit 11 may include a plurality of ink cartridges. In this case, all of the plurality of ink cartridges may supply the pigment ink to the recording head 39, all of the plurality of ink cartridges may supply the dye ink to the recording head 39, or the plurality of inks A part of the cartridge may supply pigment ink to the recording head 39, and the rest of the plurality of ink cartridges may supply dye ink to the recording head 39.

  In the above embodiment, the positioning unit 90 positions the paper 12 supported by the bottom plate 32 by center alignment, but the positioning method is not limited to center alignment. For example, the positioning unit 90 may position the paper 12 by right edge alignment or left edge alignment. The right end alignment means an alignment in which the paper 12 is positioned in the left-right direction 9 with the right end as a reference position. The left end alignment means an alignment in which the paper 12 is positioned in the left-right direction 9 with the left end as a reference position.

  In the case of right end alignment or left end alignment, the positioning unit 90 includes only one guide member instead of a pair. One guide member contacts one of the right end and the left end of the paper 12 supported by the bottom plate 32. On the other hand, the other of the right end and the left end of the paper 12 abuts on a side plate standing from the other of the right end and the left end of the bottom plate 32. In the case of the right end alignment, the right end of the sheet 12 comes into contact with a side plate standing from the right end of the bottom plate 32, and the left end of the sheet 12 comes into contact with the guide member. In the case of the left end alignment, the left end of the sheet 12 comes into contact with the side plate standing from the left end of the bottom plate 32, and the right end of the sheet 12 comes into contact with the guide member.

  The wave shape forming mechanism is not limited to the contact member 80 and the support rib 52. For example, instead of each contact member 80, a roller that contacts the paper 12 from above may be provided below the upper end of the support rib 52. Further, instead of the support ribs 52, rollers that contact the paper 12 from below may be provided above the contact position of the contact member 80 with respect to the paper 12.

  In the above-described embodiment, the multifunction machine 10 includes the waveform forming mechanism that forms the paper 12 in a waveform, but may not include the waveform forming mechanism.

  In the above embodiment, the conveying device is provided in the printer unit 11. However, the conveyance device may be provided in, for example, a scanner other than the printer unit 11.

11: Printer unit (image recording device)
12 ... paper (sheet)
20 ... Feed tray (sheet tray)
23... Carriage 39... Recording head 52... Support rib (waveform forming mechanism)
54 ... Conveying roller pair (conveying section)
80 ... Contact member (wave shape forming mechanism)
90 ... Positioning part 110 ... Media sensor (sensor)
130: Control unit 140: Storage unit

Claims (11)

A support for supporting the sheet;
A sensor facing the support part, irradiating light toward the support part, and outputting an electrical signal corresponding to the amount of reflected light of the light;
A carriage having the sensor and reciprocating in the width direction along the sheet support surface of the support;
A control unit,
The control unit
Irradiating the sensor with a first amount of light while moving the carriage in the width direction to obtain a first electrical signal output by the sensor;
Irradiating the sensor with a second light amount smaller than the first light amount while moving the carriage in the width direction to obtain a second electrical signal output by the sensor;
An average value of a first value based on a first range having a large signal value in the first electric signal and a second value based on a second range having a small signal value among the second electric signal is calculated. A sheet end detection device that determines a position in the width direction corresponding to an average value as an end in the width direction of a sheet supported by the support unit.   The sheet end detection device according to claim 1, wherein the control unit executes the acquisition of the second electric signal before the acquisition of the first electric signal. A corrugated forming mechanism for forming a sheet supported by the support portion into a corrugated shape in which a plurality of convex portions approaching the sensor and concave portions moving away from the sensor are alternately arranged in the width direction,
The first light amount has a first difference between a value of the first electric signal corresponding to the reflected light reflected by the convex portion and a value of the first electric signal corresponding to the reflected light reflected by the concave portion. The sheet end detection device according to claim 1, wherein the light amount is a value. A storage unit storing at least one of the type of sheet supported by the support unit and the first light amount or the second light amount corresponding to each of the types;
The said control part refers to the said memory | storage part, The at least one of the said 1st light quantity or the said 2nd light quantity is determined based on the kind of sheet | seat which the said support part supported. Sheet edge detection device.   The sheet end detection device according to any one of claims 1 to 4, wherein the first value is a maximum value in the first electric signal.   The sheet end detection device according to claim 1, wherein the second value is a minimum value in the first electric signal. A sheet edge detection device according to any one of claims 1 to 6,
A conveyance unit that conveys the sheet,
The control unit causes the conveyance unit to convey the sheet,
The said support part is a conveying apparatus which supports the sheet | seat conveyed by the said conveying part. The sheet edge detection device according to any one of claims 1 to 4,
A transport unit for transporting the sheet;
A sheet tray for supporting a sheet fed toward the transport unit;
A positioning part that positions the sheet supported by the sheet tray in the width direction with the center part in the width direction as a reference position, and
The control unit causes the conveyance unit to convey the sheet,
The support unit supports a sheet conveyed by the conveyance unit,
The transport device, wherein the first value of the first electric signal is an average value of signal values at a plurality of positions close to the reference position in the width direction. A transport device according to claim 7 or 8,
An image recording apparatus comprising: a recording head mounted on the carriage and ejecting ink toward the support portion.   The second light amount is a value of the second electric signal corresponding to light reflected at a position where ink is not deposited on the support portion, and the second light amount corresponding to light reflected at a position where ink can be deposited on the support portion. The image recording apparatus according to claim 9, wherein a difference between the two electric signals is a light amount that becomes a second difference value. The image recording apparatus according to claim 9, wherein the recording head discharges pigment ink.

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