JP2019168228A - Sensor unit and image forming device having the same - Google Patents

Abstract

To provide a sensor unit capable of accurately detecting edge positions in the width direction of recording media of various sizes with a simple and low-cost configuration, and an image forming device including the sensor unit.SOLUTION: The sensor unit includes an edge detection sensor, a unit housing, a sensor carriage, and a carriage moving mechanism. The edge detection sensor is disposed in a conveyance unit that conveys a sheet, and detects edge positions on both sides of the sheet width direction perpendicular to the sheet conveyance direction. The sensor carriage is mounted with the edge detection sensor and is supported so as to be reciprocally movable in the sheet width direction with respect to the unit housing. The carriage moving mechanism reciprocates the sensor carriage in the sheet width direction. The sensor carriage is selectively positioned at a first position in contact with one end side in the sheet width direction of the unit housing and a second position in contact with the other end side in the sheet width direction.SELECTED DRAWING: Figure 18

Description

  The present invention relates to a sensor unit that is mounted on an image forming apparatus such as a facsimile, a copying machine, and a printer and that includes a sensor that detects an edge of a sheet-like recording medium, and an image forming apparatus including the sensor unit.

  An image forming apparatus such as a facsimile, a copying machine, and a printer is configured to record an image on a recording medium such as paper, cloth, or OHP sheet. These image forming apparatuses can be classified into an electrophotographic system, an ink jet system, and the like according to a recording system.

  When printing on a recording medium using the image forming apparatus, if the recording medium is displaced in a direction (recording medium width direction) orthogonal to the transport direction, the printing position for each recording medium is displaced. Therefore, when bookbinding is performed after printing, high accuracy is required for the printing position accuracy for each page. In particular, when an ink jet recording apparatus is used, the ink soaks into the recording medium and shows through easily, and therefore a very high accuracy (for example, a few millimeters or less) is required for the printing position accuracy during double-sided printing.

  Therefore, some conventional image forming apparatuses are provided with a CIS (contact image sensor) that detects the position of the edge in the width direction of the paper, facing the conveyance belt that conveys the paper (recording medium). In this image forming apparatus, the position of the edge in the width direction of the paper is detected based on the difference in intensity of light received by the CIS depending on the presence or absence of the paper.

  For example, Patent Document 1 discloses that a deviation amount detecting unit that detects a lateral deviation amount and a skew feeding amount of a sheet by CIS, and if the detected positional deviation amount of the sheet is larger than a predetermined threshold, the sheet is generated as an error sheet. Error sheet detection means for detecting, and when an error sheet occurs, a sheet detection means for detecting whether there is a sheet in the duplex path, and a sheet in the duplex path, if there is a sheet in the duplex path, the error sheet is Determine a sheet source that is conveyed from the sheet storage unit or a sheet that has been conveyed through a double-sided path, and a sheet to be discharged based on the determination result. An image forming apparatus including a sheet discharging unit that discharges the sheet is disclosed.

  Further, Patent Document 2 binarizes the output value of the CIS arranged in the transport path of the transported object (paper), and stores the position at which the binarized value switches for each transported object size. An edge detection device that determines the edge position of an object to be conveyed when it is within the edge detection range is disclosed. It also describes that the conveyed object is shifted in the width direction on the basis of the amount of deviation between the detected edge position and the reference position.

JP 2003-327345 A Japanese Patent Laid-Open No. 2006-145814

  However, the methods disclosed in Patent Documents 1 and 2 have a problem in that they cannot handle paper having a size larger than the effective reading range of CIS. In addition, since the largest existing CIS is compatible with A3 size, when a large CIS corresponding to paper larger than A3 size is installed, it becomes a custom-made product, and the image forming apparatus is expensive. there were.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a sensor unit that can accurately detect the edge positions in the width direction of recording media of various sizes with a simple and low-cost configuration, and an image forming apparatus including the sensor unit. Objective.

  In order to achieve the above object, a first configuration of the present invention is a sensor unit including an edge detection sensor, a unit housing, a sensor carriage, and a carriage moving mechanism. The edge detection sensor is disposed in a conveyance unit that conveys the sheet, and detects an edge position in the sheet width direction orthogonal to the sheet conveyance direction. The unit housing houses an edge detection sensor. The sensor carriage is mounted with an edge detection sensor and is supported so as to be reciprocally movable in the sheet width direction with respect to the unit housing. The carriage moving mechanism reciprocates the sensor carriage in the sheet width direction. The sensor carriage is selectively positioned at a first position in contact with one end side in the sheet width direction of the unit housing and a second position in contact with the other end side in the sheet width direction.

  According to the first configuration of the present invention, the sensor carriage is reciprocated between the first position on one end side in the sheet width direction and the second position on the other end side in accordance with the sheet size information. The edge position of a sheet having a size larger than the reading range of the edge detection sensor can be detected. Further, since the sensor carriage is positioned at the first position and the second position by contacting the unit housing, the sensor carriage is repeatedly reciprocated between the first position and the second position. Position reproducibility can be improved.

Side surface sectional drawing which shows schematic structure of the printer 100 provided with the sensor unit 30 which concerns on one Embodiment of this invention. External perspective view of sensor unit 30 of this embodiment mounted on printer 100 Side sectional view of sensor unit 30 The perspective view of the flame | frame which comprises the unit housing 31 of the sensor unit 30 External perspective view of CIS carriage 35 External perspective view of a carriage body 37 constituting the CIS carriage 35 The perspective view which looked at CIS40 mounted in the carriage main body 37 from the upper surface side. The perspective view which looked at CIS40 mounted in the carriage main body 37 from the lower surface side Block diagram showing a control path of the printer 100 of the present embodiment The perspective view of the carriage moving mechanism 50 provided in the sensor unit 30 of this embodiment. The perspective view which looked at the rack 57 periphery which comprises the carriage moving mechanism 50 from the downward direction. FIG. 5 is a perspective view of the carriage moving mechanism 50 and includes a cross section along the rotation axis of the two-stage gear 53. Partial perspective view of the front side end of the CIS carriage 35 A perspective view of the connecting plate 60 fixed to the CIS carriage 35. Side view of the CIS carriage 35 viewed from the front side (left direction in FIG. 13) Side view of the rack 57 as seen from the front side (left direction in FIG. 13) Partial perspective view of the front end of the carriage body 37 Partial sectional view of the front side end of the sensor unit 30 showing a state in which the CIS carriage 35 has moved to the front side. Partial perspective view of the rear side end of the CIS carriage 35 Partial sectional view of the rear side end portion of the sensor unit 30 showing a state in which the CIS carriage 35 has moved to the rear side. Partial perspective view of the periphery of the rear end of the sensor unit 30 Partial sectional view of the rear side end portion of the sensor unit 30 showing a state in which the CIS carriage 35 has moved to the rear side. Partial sectional view in which the periphery of the rear end of the sensor unit 30 is cut along the longitudinal direction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing a schematic structure of an ink jet recording type printer 100 provided with a sensor unit 30 according to an embodiment of the present invention.

  As shown in FIG. 1, the printer 100 has a paper feed cassette 2 a that is a paper storage portion disposed below the inside of the printer main body 1, and a manual paper feed tray 2 b provided outside the right side surface of the printer main body 1. ing. A paper feeding device 3a is disposed above the paper feeding cassette 2a on the downstream side in the paper conveyance direction (the right side of the paper feeding cassette 2a in FIG. 1). A paper feeding device 3b is disposed on the downstream side of the manual paper feeding tray 2b in the paper conveyance direction (left side of the manual paper feeding tray 2b in FIG. 1). By the paper feeding devices 3a and 3b, the paper P is separated and sent out one by one.

  In addition, a first paper transport path 4 a is provided inside the printer 100. The first paper transport path 4a is located on the upper right side with respect to the paper feed cassette 2a, and is located on the left side with respect to the manual paper feed tray 2b. The paper P sent out from the paper feed cassette 2a is transported vertically upward along the side surface of the printer body 1 through the first paper transport path 4a, and the paper sent out from the manual paper feed tray 2b is the first paper. It is conveyed toward the substantially horizontal left through the conveyance path 4a.

  A sensor unit 30 for detecting the position (edge position) of the end of the sheet P in the width direction (perpendicular to the sheet conveyance direction) is provided at the downstream end of the first sheet conveyance path 4a with respect to the sheet conveyance direction. Has been placed. Further, the first belt conveyance unit 5 and the recording unit 9 are disposed in the immediate vicinity of the sensor unit 30 on the downstream side.

  The sensor unit 30 is provided with a registration roller pair 13. The registration roller pair 13 feeds the paper P toward the first belt conveyance unit 5 while correcting the oblique feeding of the paper P and timings the ink ejection operation performed by the recording unit 9. The detailed structure of the sensor unit 30 will be described later.

  The first belt conveyance unit 5 includes an endless first conveyance belt 8 wound around a first drive roller 6 and a first driven roller 7. The first conveyor belt 8 is provided with a large number of air suction holes (not shown). The paper P sent out from the registration roller pair 13 passes below the recording unit 9 while being sucked and held by the first transport belt 8 by the paper suction unit 20 provided inside the first transport belt 8.

  The recording unit 9 includes line heads 10C, 10M, 10Y, and 10K. The line heads 10 </ b> C to 10 </ b> K record an image on the sheet P conveyed while being sucked and held on the conveyance surface of the first conveyance belt 8. Each of the line heads 10C to 10K is supplied with four colors (cyan, magenta, yellow, and black) of ink stored in an ink tank (not shown) for each color of the line heads 10C to 10K.

  By sequentially ejecting the respective inks from the line heads 10C to 10K toward the paper P attracted to the first transport belt 8, the four inks of yellow, magenta, cyan, and black are superimposed on the paper P. A full color image is recorded. Note that the printer 100 can also record a monochrome image.

  A second belt conveyance unit 11 is disposed on the downstream side (left side in FIG. 1) of the first belt conveyance unit 5 with respect to the paper conveyance direction. The paper P on which an image is recorded in the recording unit 9 is sent to the second belt conveyance unit 11, and the ink ejected on the surface of the paper P while passing through the second belt conveyance unit 11 is dried. Since the configuration of the second belt conveyance unit 11 is the same as that of the first belt conveyance unit 5, the description thereof is omitted.

  A decurler unit 14 is provided on the downstream side of the second belt conveyance unit 11 with respect to the sheet conveyance direction and in the vicinity of the left side surface of the printer main body 1. The paper P from which the ink has been dried by the second belt conveyance unit 11 is sent to the decurler unit 14, and the curl generated on the paper P is corrected.

  A second paper transport path 4b is provided on the downstream side (upper side in FIG. 1) of the decurler unit 14 with respect to the paper transport direction. When double-sided recording is not performed, the paper P that has passed through the decurler unit 14 is discharged from the second paper transport path 4b to a paper discharge tray 15 provided outside the left side surface of the printer 100 via a pair of discharge rollers. When recording on both sides of the sheet P, the sheet P that has finished recording on one side and has passed through the second belt conveying unit 12 and the decurler unit 14 passes through the second sheet conveying path 4b to the reverse conveying path 16. Be transported. The paper P sent to the reverse conveyance path 16 is switched in the conveyance direction in order to reverse the front and back, passes through the upper part of the printer 100, and is conveyed to the registration roller pair 13. Thereafter, the sheet is conveyed again to the first belt conveying unit 5 with the surface on which no image is recorded facing upward.

  A maintenance unit 19 is disposed below the second belt conveyance unit 12. The maintenance unit 19 moves below the recording unit 9 when performing maintenance of the recording heads of the line heads 10C to 10K, and wipes off the ink ejected (purged) from the ink ejection nozzles of the recording head. Collect the remaining ink.

  Next, the detailed structure of the sensor unit 30 will be described. 2 is an external perspective view of the sensor unit 30 mounted on the printer 100, FIG. 3 is a side sectional view of the sensor unit 30, and FIG. 4 is a perspective view of a frame constituting the unit housing 31 of the sensor unit 30. It is.

  The sensor unit 30 includes a unit housing 31, a registration roller pair 13, a CIS carriage 35, and a carriage moving mechanism 50. The unit housing 31 supports the registration roller pair 13 so as to be rotatable, and supports the CIS carriage 35 so as to be movable in the paper width direction (arrow AA ′ direction). A registration entry guide 33 that guides the sheet P to the nip portion of the registration roller pair 13 is provided at the upstream end of the unit housing 31 with respect to the sheet conveyance direction (arrow B direction).

  As shown in FIG. 4, the unit housing 31 includes side frames 31 a and 31 b arranged on the front side and the back side of the printer 100, and a connection frame 31 c connected to the side frames 31 a and 31 b in a bridging manner. . Between the side frames 31a and 31b, two shafts 47 that slidably support the CIS carriage 35 are fixed in parallel to each other.

  The CIS carriage 35 is disposed adjacent to the downstream side (left side in FIG. 3) of the registration roller pair 13 with respect to the paper conveyance direction (arrow B direction). The CIS carriage 35 includes a carriage body 37 (see FIG. 6) in which the CIS 40 and the light source unit 41 are accommodated. The CIS 40 and the light source unit 41 are housed below and above the carriage main body 37, respectively, and two contact glasses 42a and 42b are disposed opposite to each other between the CIS 40 and the light source unit 41. A part of the sheet conveyance path is formed by the upper surface of the contact glass 42a and the lower surface of the contact glass 42b.

  The CIS 40 detects the edge position of the paper P in the width direction based on the light intensity difference between the portion where the light from the light source unit 41 enters and the portion blocked by the paper P. The light source unit 41 includes an LED 41 a disposed at one end in the paper width direction, and a light guide plate 41 b that diffuses light emitted from the LED 41 a throughout the paper width direction and guides the light to the CIS 40.

  5 is an external perspective view of the CIS carriage 35, FIG. 6 is an external perspective view of the carriage body 37 constituting the CIS carriage 35, and FIGS. 7 and 8 are top views of the CIS 40 mounted on the carriage body 37, respectively. It is the perspective view seen from the side and the lower surface side.

  The carriage body 37 includes a CIS storage portion 37a in which the CIS 40 is stored, and a shaft guide portion 37b into which the shaft 47 of the unit housing 31 is slidably inserted. The CIS storage portion 37 a is provided over substantially the entire longitudinal direction of the carriage body 37. Two pairs of shaft guide portions 37b are provided in the paper conveyance direction at two locations on both ends of the carriage body 37 in the longitudinal direction.

  In the CIS 40, a large number of detection units 43 made of photoelectric conversion elements are arranged in the paper width direction (left and right direction in FIG. 7). The detection unit 43 is mounted on the upper surface of the CIS substrate 45. A CIS-side connector 46 to which one end of the FFC 67 (see FIG. 21) is connected is provided on the lower surface side of the CIS substrate 45 (the side opposite to the detection unit 43).

  FIG. 9 is a block diagram illustrating a control path of the printer 100 according to the present embodiment. The CPU 70 comprehensively controls the entire printer 100. When the printing operation on the paper P by the printer 100 is started in response to print data received from an external computer or the like, the CPU 70 performs various settings for reading signals from the CIS 40 to the CIS control circuit 71. . Further, the CPU 70 transmits a control signal to the CIS drive motor 51 based on the paper size information included in the received print data, and moves the CIS carriage 35 in the sensor unit 30 by a predetermined amount.

  The CIS control circuit 71 sends to the CIS 40 a reference clock signal for reading a signal from the CIS 40 and an accumulation time determination signal for determining the charge accumulation time in the CIS 40 according to the contents set by the CPU 70. Further, the CIS control circuit 71 sends a PWM signal to the LED drive circuit 73 in order to set a current value to be passed through the LED 41a. The LED drive circuit 73 generates a DC voltage corresponding to the PWM signal from the CIS control circuit 71, and uses this as a reference voltage for the current flowing through the LED 41a. The CIS control circuit 71 generates a comparison reference voltage (threshold voltage) for binarizing the analog signal (output signal) from the CIS 40 by the binarization circuit 75.

  At the timing when the paper P in the standby state is conveyed toward the recording unit 9 (see FIG. 1) by the registration roller pair 13 (see FIG. 3), the CPU 70 instructs the CIS control circuit 71 to detect the edge position. To do. Upon receiving the edge position detection instruction from the CPU 70, the CIS control circuit 71 sends a control signal for lighting the LED 41a to the LED drive circuit 73 in synchronization with the accumulation time determination signal. The LED drive circuit 73 turns on the LED 41a for a certain period according to the control signal from the CIS control circuit 71.

  The CIS 40 applies a voltage corresponding to the amount of light accumulated in each pixel (photoelectric conversion element) of the pixel group of the detection unit 43 while the LED 41a is turned on one pixel at a time using the next accumulation time determination signal and the reference clock signal. Output as an output signal. The output signals output from the CIS 40 are respectively binarized by comparison with a comparison reference voltage (threshold voltage) in the binarization circuit 75 and input to the CIS control circuit 71 as a digital signal.

  The CIS control circuit 71 sequentially confirms each pixel of the 0/1 value of the digital signal binarized by the binarization circuit 75 for each of the output signals output from the CIS 40. The CIS control circuit 71 detects the pixel position (the position of the photoelectric conversion element) of the detection unit 43 where the value of the digital signal is switched from 0 to 1 or from 1 to 0.

  When the position of the pixel whose digital signal value has been switched is detected by the CIS control circuit 71, the position of the switched pixel is determined as the edge position in the width direction of the paper P. The CPU 70 uses the edge position determined by the CIS control circuit 71 and the edge position (reference edge position) when the paper P is transported at an ideal transport position (reference transport position) that passes through the center position of the sheet passing area. Is calculated. The calculated deviation amount is transmitted to the nozzle shift control unit 77. The nozzle shift control unit 77 shifts the use area of the ink discharge nozzles of the line heads 10 </ b> C to 10 </ b> K in the recording unit 9 in accordance with the transmitted amount of deviation in the width direction of the paper P.

  Next, the moving mechanism of the CIS carriage 35 in the sensor unit 30 of this embodiment will be described. 10 is a perspective view of the carriage moving mechanism 50 provided in the sensor unit 30 of the present embodiment, FIG. 11 is a perspective view of the periphery of the rack 57 constituting the carriage moving mechanism 50, and FIG. FIG. 4 is a perspective view of the mechanism 50 and includes a cross section along the rotation axis of the two-stage gear 53.

  The carriage moving mechanism 50 includes a CIS drive motor 51, a worm gear 53, a two-stage gear 55, and a rack 57. The worm gear 53 is fixed to the rotating shaft of the CIS drive motor 51.

  The two-stage gear 55 has a small diameter portion 55a and a large diameter portion 55b, and meshes with the worm gear 53 at the small diameter portion 55a. As shown in FIG. 12, the two-stage gear 55 has a built-in torque limiter 65. When the rotational load applied to the two-stage gear 55 exceeds a predetermined torque, the small-diameter portion 55a and the large-diameter portion 55b are independent of each other. It can be rotated.

  The rack 57 has rack teeth 57 a that mesh with the large diameter portion 55 b of the two-stage gear 55. An engagement protrusion 57 b that engages with an engagement hole 60 a formed at one end of the connecting plate 60 is provided on the lower surface of the rack 57. A screw fixing hole 60 b is formed at the other end of the connecting plate 60. In addition, light shielding plates 61 a and 61 b are projected from the side surface of the rack 57. A PI (photo interrupter) sensor 63 is disposed at a position of the rack 57 facing the light shielding plates 61a and 61b. The PI sensor 63 is fixed to the unit housing 31 (see FIG. 2) via a sensor holding stay 62.

  With the movement of the rack 57, the light shielding plates 61a and 61b shield the detection unit 63a of the PI sensor 63, so that the light reception signal level changes from HIGH to LOW. Further, the light receiving signal level changes from LOW to HIGH as the light shielding plates 61a and 61b are retracted from the detection unit 63a. The light reception signal of the detection unit 63a is transmitted to the CPU 70 (see FIG. 9).

  FIG. 13 is a partial perspective view of the end portion on the front side (in the direction of arrow A) of the CIS carriage 35, and FIG. 14 is a perspective view of the connecting plate 60 fixed to the CIS carriage 35. The connecting plate 60 is made of metal, and is fixed to the CIS carriage 35 by fastening screws 66 to the screw fixing holes 60b as shown in FIG.

  As shown in FIG. 14, a circular engagement hole 60 a that engages with the engagement protrusion 57 b of the rack 57 is formed at one end of the connecting plate 60. The inner diameter of the engagement hole 60a is slightly larger than the outer diameter of the engagement protrusion 57b. An elongated screw fixing hole 60b extending in the transport direction (the direction of arrow B) is formed at the other end of the connecting plate 60.

  By making the screw fixing hole 60b into a long hole shape, the fixing position of the connecting plate 60 with respect to the CIS carriage 35 can be changed in the transport direction. As a result, the positional deviation of the CIS carriage 35 in the conveyance direction (sub-scanning direction) can be adjusted within the range of the screw fixing hole 60b. Therefore, when the relative position between the CIS carriage 35 and the rack 57 is displaced in the conveyance direction due to component tolerance or the like. Even so, by adjusting the fixing position of the connecting plate 60, the engaging protrusion 57b of the rack 57 and the engaging hole 60a of the connecting plate 60 can be reliably engaged.

  15 is a side view of the CIS carriage 35 viewed from the front side (left direction in FIG. 13), and FIG. 16 is a side view of the rack 57 viewed from the front side (left direction in FIG. 13). As shown in FIG. 15, the CIS carriage 35 is arranged to be inclined by θ1 with respect to the horizontal plane H so that the downstream side (left side in FIG. 15) faces downward in the transport direction. Therefore, the connection plate 60 fixed to the CIS carriage 35 and the opening surface O of the engagement hole 60a formed in the connection plate 60 are also inclined by θ1 with respect to the horizontal plane H.

  On the other hand, as shown in FIG. 16, the engagement protrusions 57 b of the rack 57 protrude from the lower surface of the rack 57 with an inclination of θ1 toward the upstream side in the transport direction. As a result, the protruding direction of the engaging protrusion 57b is substantially perpendicular to the opening surface O of the engaging hole 60a, so that the engagement protrusion 57b and the engaging hole 60a are engaged when the CIS carriage 35 reciprocates. Is difficult to come off.

  Next, a procedure for switching the arrangement of the CIS carriage 35 will be described. When the paper size information included in the print data received from an external computer or the like is a standard size (A3 size or less), the CIS carriage 35 is moved to the front side (arrow A direction) of the printer 100.

  Specifically, the rack 57 is moved in the arrow A direction via the worm gear 53 and the two-stage gear 55 by rotating the CIS drive motor 51 in a predetermined direction. As a result, the CIS carriage 35 connected to the rack 57 by the connecting plate 60 also moves in the arrow A direction while sliding along the shaft 47.

  FIG. 17 is a partial perspective view of the end portion on the front side (arrow A direction) of the carriage body 37, and FIG. 18 shows the sensor unit 30 in a state where the CIS carriage 35 has moved to the front side (arrow A direction). It is a fragmentary sectional view of a front side edge part. As shown in FIG. 17, the contact surface 37 c protrudes most in the direction of arrow A on the front side of the carriage body 37. Therefore, when the CIS carriage 35 moves by a predetermined distance in the direction of arrow A, the contact surface 37c of the carriage body 37 contacts the inner surface of the side frame 31a of the unit housing 31 as shown in FIG. At this time, the CIS carriage 35 is disposed at a position (home position, first position) that is moved to the most front side. Accordingly, the detection unit 43 (effective reading area) of the CIS 40 is arranged at a position overlapping the edge portions on both sides in the width direction of the A3 size.

  On the other hand, if the paper size information is larger than A3 size, the CIS carriage 35 is moved to the back side of the printer 100 (arrow A ′ direction). Specifically, by rotating the CIS drive motor 51 in the reverse direction, the rack 57 is moved in the arrow A ′ direction via the worm gear 53 and the two-stage gear 55. As a result, the CIS carriage 35 connected to the rack 57 by the connecting plate 60 also moves in the direction of the arrow A ′ while sliding along the shaft 47.

  FIG. 19 is a partial perspective view of the end of the carriage body 37 on the back side (in the direction of arrow A ′), and FIG. 20 shows a sensor unit that shows a state in which the CIS carriage 35 has moved to the back side (in the direction of arrow A ′). It is a fragmentary sectional view of the back side end part of 30. As shown in FIG. 19, the contact surface 37 d protrudes most in the direction of arrow A ′ on the back side of the carriage body 37. Therefore, when the CIS carriage 35 moves by a predetermined distance in the direction of the arrow A ′, the contact surface 37 d of the carriage body 37 contacts the inner surface of the side frame 31 b of the unit housing 31 as shown in FIG. At this time, the CIS carriage 35 is arranged at a position (second position) moved to the rearmost side. Thereby, the detection unit 43 (effective reading area) of the CIS 40 is arranged at a position overlapping the edge portion on the back side of the large size.

  In the present embodiment, the CIS drive motor 51 continues to rotate for a predetermined time after the contact surfaces 37c and 37d of the carriage body 37 contact the inner surfaces of the side frames 31a and 31b. Further, the rotational torque of the torque limiter 65 is set smaller than the torque applied to the two-stage gear 55 when the CIS drive motor 51 rotates with the contact surfaces 37c and 37d in contact with the side frames 31a and 31b.

  Thus, the small diameter portion 55a and the large diameter portion of the two-stage gear 55 are stopped until the CIS drive motor 51 stops after the contact surfaces 37c, 37d of the carriage body 37 contact the inner surfaces of the side frames 31a, 31b of the unit housing 31. 55b rotates independently.

  According to the present embodiment, the CIS carriage 35 is positioned at the first position and the second position by the contact surfaces 37 c and 37 d of the carriage body 37 contacting the inner surfaces of the side frames 31 a and 31 b of the unit housing 31. Is done. Accordingly, it is possible to improve the position reproducibility when the CIS carriage 35 is repeatedly reciprocated between the first position and the second position.

  Further, the pressing force of the carriage body 37 against the side frames 31a and 31b can be stabilized by using the load of the torque limiter 65 without applying a load to the CIS drive motor 51. Therefore, when the CIS drive motor 51 is stopped, the backlash of the worm gear 53, the two-stage gear 55, and the rack 57 can be prevented, and the positional accuracy of the CIS carriage 35 is improved.

  Further, when the contact surface 37c comes into contact with the side frame 31a, the light shielding plate 61b of the rack 57 shields the detection unit 63a of the PI sensor 63 as shown in FIG. On the other hand, when the contact surface 37d contacts the side frame 31b, the light shielding plate 61a of the rack 57 shields the detection unit 63a of the PI sensor 63 from light. As a result, when the CIS carriage 35 normally reciprocates between the first position and the second position, the light reception signal level of the PI sensor 63 switches from LOW to HIGH to LOW. When this change in the received light signal level is detected by the CPU 70 (see FIG. 9), it is determined that the CIS carriage 35 has normally reciprocated.

  If the light reception signal level of the PI sensor 63 does not change from the LOW or HIGH state even though the CIS drive motor 51 is driven, it is determined that the CIS carriage 35 is malfunctioning or the CIS drive motor 51 is damaged. Error display on an operation panel (not shown) of the printer 100. That is, the PI sensor 63 functions as an error detection device for the reciprocating operation of the CIS carriage 35.

  With this configuration, it is possible to detect a malfunction in the reciprocating movement between the first position and the second position of the CIS carriage 35 by using one PI sensor 63. Therefore, the number of sensors can be reduced as compared with a configuration in which separate sensors are arranged at the first position and the second position to detect malfunction.

  Next, wiring of an FFC (flexible flat cable) 67 to the CIS carriage 35 will be described. FIG. 21 is a partial perspective view of the vicinity of the rear end portion of the sensor unit 30 of the present embodiment, and FIG. 22 is a partial perspective view of the vicinity of the rear end portion of the CIS carriage 35.

  The FFC 67 is a ribbon-like wiring cable in which a plurality of conductive wires are arranged in parallel in a covering member. Since the FFC 67 is excellent in flexibility and can be bent into an arbitrary shape, the wiring space can be reduced. In the present embodiment, one end of the FFC 67 passes through the cable insertion hole 32 formed in the side frame 31b and the cable guide hole 37e formed in the rear end of the carriage body 37, and the CIS connector 46 of the CIS 40. (See FIG. 8).

  The other end of the FFC 67 is bent upward from the cable insertion hole 32, wired along the upper surface of the unit housing 31, folded back at a right angle, and then connected to the unit housing side connector 69. FIG. 21 shows a state in which the CIS carriage 35 is disposed at the first position, and the FFC 67 is wired without bending along the side frame 31b.

  FIG. 23 is a partial cross-sectional view in which the periphery of the rear end portion of the sensor unit 30 is cut along the longitudinal direction. FIG. 23 shows a state in which the CIS carriage 35 is moving from the first position to the second position, and the FFC 67 drawn out from the cable insertion hole 32 is bent toward the outside of the side frame 31b.

  According to the configuration of the present embodiment, the CIS carriage 35 slides between the first position and the second position along the two shafts 47, so that the CIS carriage 35 is stable without rattling. Move back and forth. Thereby, when the CIS carriage 35 is reciprocated, an extra load is not applied to the FFC 67 connected to the CIS carriage 35, and damage to the FFC 67 can be suppressed.

  Further, since the cable insertion hole 32 for drawing the FFC 67 to the outside of the unit housing 31 and the cable guide hole 37e for drawing the FFC 67 to the outside of the CIS carriage 35 are provided in the axial direction of the shaft 47, the FFC 67 faces the outside of the side frame 31b. Can bend in the direction. As a result, the FFC 67 can be prevented from being twisted or bent due to the reciprocating movement of the CIS carriage 35, and disconnection of the FFC 67 can be suppressed.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above-described embodiment, an example using the transmission type CIS 40 including the detection unit 43 that receives the laser light from the light source unit 41 is illustrated. However, for example, a light-emitting unit that emits light to the paper P is provided and detected. The edge position of the paper P is determined by the difference in intensity between the reflected light from the paper P and the reflected light from the non-passing area of the paper P using the reflection type CIS 40 that detects the reflected light from the paper P in the unit 43. You can also. In this case, the color different from the color (white) of the paper P at the position facing the detection unit 43 of the CIS 40 so that the difference in intensity between the reflected light from the paper P and the reflected light from the non-passing area of the paper P becomes large. It is preferable to arrange the background member.

  In the above embodiment, the CIS 40 is used as the sensor for detecting the edge position of the paper P. However, a sensor other than the CIS such as a CCD may be used.

  In the above embodiment, the inkjet recording type printer 100 that records an image by ejecting ink onto the paper P from the ink ejection nozzles of the line heads 10C to 10K has been described as an example. In addition to the printer 100 of the type, for example, an electrostatic latent image is formed by irradiating a laser on an image carrier such as a photosensitive drum, and the toner is attached to the electrostatic latent image to form a toner image, and then the toner The present invention can also be applied to an electrophotographic image forming apparatus in which an image is transferred onto a sheet (recording medium), and the transferred unfixed toner is heated and pressed to form a permanent image.

5 1st belt conveyance part (conveyance part)
9 Recording unit (image forming unit)
13 Registration roller pair 30 Sensor unit 31 Unit housing 31a, 31b Side frame 32 Cable insertion hole (second guide hole)
35 CIS carriage (sensor carriage)
37 Carriage body 37a CIS storage part 37b Shaft guide part 37c, 37d Contact surface 37e Cable guide hole (first guide hole)
40 CIS (edge detection sensor)
41 Light source unit 43 Detection unit 45 CIS board 50 Carriage moving mechanism 51 CIS drive motor 53 Worm gear 55 Two-stage gear 57 Rack 57a Rack tooth 57b Engagement protrusion 60 Connection plate 60a Engagement hole 60b Screw fixing hole 61a, 61b Light shielding plate 63 PI Sensor 63a Detector 65 Torque limiter 67 FFC (flexible flat cable)
100 Printer (image forming device)
P paper (recording medium)
O opening surface

Claims (6)

An edge detection sensor that is disposed in a conveyance unit that conveys the sheet and detects an edge position of the sheet in the sheet width direction orthogonal to the sheet conveyance direction;
A unit housing for housing the edge detection sensor;
In the sensor unit with
A sensor carriage mounted with the edge detection sensor and supported so as to be reciprocally movable in the sheet width direction with respect to the unit housing;
A carriage moving mechanism for reciprocating the sensor carriage in the sheet width direction,
The sensor carriage is selectively positioned at a first position contacting the one end side of the unit housing in the sheet width direction and a second position contacting the other end side of the sheet width direction. Sensor unit characterized by. The sensor carriage has a carriage body on which the edge detection sensor is mounted,
The carriage body has a pair of contact surfaces protruding from both ends in the sheet width direction,
The unit housing has a pair of side frames opposed to the seat width direction,
The sensor carriage is positioned at the first position by contacting one of the contact surfaces with one of the side frames, and the sensor carriage by positioning the other of the contact surfaces with the other of the side frames. The sensor unit according to claim 1, wherein the sensor unit is positioned at the second position. The unit housing has two shafts connected in the seat width direction between the pair of side frames,
The carriage body is provided with a pair of shaft guide portions arranged at predetermined intervals in the sheet conveying direction and slidably inserted through the two shafts at both ends in the sheet width direction. The sensor unit according to claim 2, wherein the sensor unit is provided. The edge detection sensor is connected to a flexible flat cable in which a plurality of conductive wires are arranged in parallel with each other in the covering member,
A first guide hole penetrating in the axial direction of the shaft is formed in one end portion of the carriage body in the sheet width direction, and overlaps the first guide hole in one end portion of the unit housing in the sheet width direction. A second guide hole penetrating in the axial direction of the shaft is formed at a position;
The sensor unit according to claim 3, wherein the flexible flat cable is guided to the outside of the unit housing through the first guide hole and the second guide hole. The edge detection sensor is a contact image sensor having a plurality of photoelectric conversion elements arranged along the sheet width direction,
5. The pixel position at which the value of a digital signal obtained by binarizing the output signal of the contact image sensor is determined as an edge position in the width direction of the recording medium. Sensor unit. A transport unit for transporting the sheet;
An image forming unit that forms an image on the sheet conveyed by the conveying unit;
The sensor unit according to any one of claims 1 to 5, which is disposed upstream of the image forming unit with respect to a sheet conveyance direction;
A control unit that corrects an image forming position in the sheet width direction by the image forming unit based on an edge position in a sheet width direction orthogonal to the sheet conveying direction of the sheet detected by the sensor unit;
An image forming apparatus.

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