JP7067167B2 - Sensor unit and image forming device equipped with it - Google Patents

Description

The present invention relates to a sensor unit equipped with a sensor for detecting an edge of a sheet-shaped recording medium, which is mounted on an image forming apparatus such as a facsimile, a copying machine, and a printer, and an image forming apparatus provided with the sensor unit.

Image forming devices such as facsimiles, copiers, and printers are configured to record images on recording media such as paper, cloth, and OHP sheets. These image forming devices can be classified into an electrophotographic method, an inkjet type, and the like depending on the recording method.

When printing is performed on a recording medium using an image forming apparatus, if the recording medium is displaced in a direction orthogonal to the transport direction (recording medium width direction), the printing position of each recording medium is displaced. Therefore, when binding a book after printing, high accuracy is required for the printing position accuracy for each page. In particular, when an inkjet recording device is used, the ink permeates into the recording medium and is likely to show through, so that the printing position accuracy at the time of double-sided printing is required to be extremely high (for example, a few mm or less).

Therefore, in some conventional image forming apparatus, a CIS (contact image sensor) for detecting the position of the end portion in the width direction of the paper is arranged so as to face the transport belt that conveys the paper (recording medium). In this image forming apparatus, the position of the edge portion in the width direction of the paper is detected based on the difference in the intensity of the light received by the CIS depending on the presence or absence of the paper.

For example, in Patent Document 1, a misalignment amount detecting means for detecting a lateral displacement amount and an oblique amount of paper by CIS, and when the detected misalignment amount of a sheet is larger than a predetermined threshold value, the occurrence of the misalignment is described as an error sheet. The error sheet detecting means for detecting, the sheet detecting means in the double-sided path for detecting whether or not the sheet exists in the double-sided path when an error sheet occurs, and the error sheet when the sheet exists in the double-sided path. A sheet determined by determining a transport source determining means for determining whether the sheet is transported from the sheet storage unit or a sheet transported through a double-sided path, and a sheet to be discharged based on the discrimination result. An image forming apparatus comprising a sheet discharging means for discharging a paper is disclosed.

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

Japanese Patent Application Laid-Open No. 2003-327345 Japanese Unexamined Patent Publication No. 2016-145814

However, the methods of Patent Documents 1 and 2 have a problem that they cannot handle paper having a size larger than the effective reading range of CIS. In addition, even the largest existing CIS is compatible with A3 size, so if a large CIS compatible with paper larger than A3 size is installed, it will be a custom-made product, and there is also the problem that the image forming device will be expensive. there were.

In view of the above problems, the present invention provides 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 apparatus provided with the sensor unit. The purpose.

In order to achieve the above object, the 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 arranged in the transport unit for transporting the sheet, and detects the edge position in the sheet width direction orthogonal to the sheet transport direction. The unit housing houses the edge detection sensor. The sensor carriage is equipped with an edge detection sensor and is supported so as to be reciprocally movable in the seat width direction with respect to the unit housing. The carriage movement mechanism reciprocates the sensor carriage in the seat width direction. The sensor carriage is selectively positioned at a first position in contact with one end side in the seat width direction of the unit housing and a second position in contact with the other end side in the seat width direction. The carriage moving mechanism includes a motor and a drive transmission gear train including a plurality of gears that transmit the driving force of the motor to the carriage. The motor continues to drive for a predetermined time even after the sensor carriage has moved to the first position or the second position. One of the plurality of gears connects the first gear and the second gear coaxially arranged, the first gear and the second gear, and a rotational load applied to the first gear and the second gear. A torque limiter for releasing the connection between the first gear and the second gear is provided only when the value exceeds a predetermined value.

According to the first configuration of the present invention, the sensor carriage is reciprocated between the first position on one end side and the second position on the other end side in the seat width direction according to the seat size information. It is possible to detect the edge position of a sheet whose size is larger than the reading range of the edge detection sensor. 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. The position reproducibility of the carriage can be improved. Further, the sensor carriage can be pressed against the unit housing with a stable load of the torque limiter without imposing a load on the motor. Therefore, when the motor is stopped, backlash of the drive transmission gear train can be prevented, and the position accuracy of the sensor carriage is improved.

A side sectional view showing a schematic structure of a printer 100 provided with a sensor unit 30 according to an embodiment of the present invention. External perspective view of the sensor unit 30 of the present embodiment mounted on the printer 100. Side sectional view of the sensor unit 30 Perspective view of the frame constituting the unit housing 31 of the sensor unit 30. External perspective view of CIS carriage 35 External perspective view of the carriage body 37 constituting the CIS carriage 35 A perspective view of the CIS 40 mounted on the carriage body 37 as viewed from the upper surface side. A perspective view of the CIS 40 mounted on the carriage body 37 as viewed from the lower surface side. A block diagram showing a control path of the printer 100 of the present embodiment. Perspective view of the carriage moving mechanism 50 provided in the sensor unit 30 of the present embodiment. A perspective view of the periphery of the rack 57 constituting the carriage moving mechanism 50 as viewed from below. It is a perspective view of the carriage movement mechanism 50, and is the figure which includes the cross section along the rotation axis of a two-step gear 53. Partial perspective view of the front end of the CIS carriage 35 Perspective view of the connecting plate 60 fixed to the CIS carriage 35 Side view of the CIS carriage 35 as viewed from the front side (left direction in FIG. 13). Side view of the rack 57 as viewed from the front side (left direction in FIG. 13). Partial perspective view of the front end of the carriage body 37 Partial cross-sectional view of the front end of the sensor unit 30 showing the state in which the CIS carriage 35 has been moved to the front side. Partial perspective view of the rear end of the CIS carriage 35 Partial cross-sectional view of the rear end of the sensor unit 30 showing the state in which the CIS carriage 35 has been moved to the rear side. Partial perspective view around the end on the back side of the sensor unit 30 Partial cross-sectional view of the rear end of the sensor unit 30 showing the state in which the CIS carriage 35 has been moved to the rear side. Partial cross-sectional view cut along the longitudinal direction around the end on the back side of the sensor unit 30.

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 inkjet recording type printer 100 provided with a sensor unit 30 according to an embodiment of the present invention.

As shown in FIG. 1, in the printer 100, a paper feed cassette 2a, which is a paper storage unit, is arranged below the inside of the printer main body 1, and a manual paper feed tray 2b is provided outside the right side surface of the printer main body 1. ing. A paper feed device 3a is arranged above the paper feed cassette 2a on the downstream side in the paper transport direction (right side of the paper feed cassette 2a in FIG. 1). Further, a paper feed device 3b is arranged on the downstream side of the manual paper feed tray 2b in the paper transport direction (left side of the manual paper feed tray 2b in FIG. 1). The paper feeding devices 3a and 3b separate and feed the paper P one by one.

Further, a first paper transport path 4a is provided inside the printer 100. The first paper transport path 4a is located on the upper right side of the paper feed cassette 2a and on the left side of the manual paper feed tray 2b. The paper P fed from the paper feed cassette 2a is conveyed vertically upward along the side surface of the printer main body 1 through the first paper transport path 4a, and the paper fed from the manual paper feed tray 2b is the first paper. It is conveyed substantially horizontally to the left through the transport path 4a.

At the downstream end of the first paper transport path 4a with respect to the paper transport direction, a sensor unit 30 for detecting the position (edge position) of the end portion in the width direction of the paper P (perpendicular to the paper transport direction) is provided. Have been placed. Further, the first belt transport unit 5 and the recording unit 9 are arranged in the immediate vicinity of the downstream side of the sensor unit 30.

The sensor unit 30 is provided with a resist roller pair 13. The resist roller pair 13 measures the timing of the ink ejection operation executed by the recording unit 9 while correcting the diagonal feed of the paper P, and feeds the paper P toward the first belt transport unit 5. The detailed structure of the sensor unit 30 will be described later.

The first belt transport unit 5 includes an endless first transport belt 8 wound around the first drive roller 6 and the first driven roller 7. The first transport belt 8 is provided with a large number of ventilation holes (not shown) for sucking air. The paper P sent out from the resist roller pair 13 passes under the recording unit 9 in a state of being sucked and held by the first transfer belt 8 by the paper suction unit 20 provided inside the first transfer belt 8.

The recording unit 9 includes line heads 10C, 10M, 10Y and 10K. The line heads 10C to 10K record an image on the paper P which is adsorbed and held on the transport surface of the first transport belt 8 and transported. Ink of four colors (cyan, magenta, yellow and black) stored in an ink tank (not shown) is supplied to each of the line heads 10C to 10K 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 adsorbed on the first transport belt 8, four color inks of yellow, magenta, cyan, and black are superimposed on the paper P. A full-color image is recorded. The printer 100 can also record a monochrome image.

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

A decaler portion 14 is provided on the downstream side of the second belt transport portion 11 with respect to the paper transport direction and in the vicinity of the left side surface of the printer main body 1. The paper P to which the ink has been dried by the second belt transport unit 11 is sent to the decaler 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 of FIG. 1) of the decaler portion 14 with respect to the paper transport direction. When double-sided recording is not performed, the paper P that has passed through the decaler portion 14 is discharged from the second paper transport path 4b to the paper ejection tray 15 provided on the outside of the left side surface of the printer 100 via the ejection roller pair. When recording on both sides of the paper P, the paper P that has passed through the second belt transport section 12 and the decaler section 14 after the recording on one side has finished passes through the second paper transport path 4b to the reverse transport path 16. Be transported. The paper P sent to the reverse transfer path 16 is switched in the transfer direction in order to reverse the front and back, passes through the upper part of the printer 100, and is conveyed to the resist roller pair 13. After that, the image is transported to the first belt transport unit 5 again with the surface on which the image is not recorded facing upward.

Further, a maintenance unit 19 is arranged below the second belt transport unit 12. The maintenance unit 19 moves below the recording unit 9 when performing maintenance on the recording heads of the line heads 10C to 10K, and wipes off the ink ejected (purged) from the ink ejection nozzle of the recording head. Collect the 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. Is. In FIG. 4, the right side is the front side of the printer 100, the left side is the back side, and the left and right sides are opposite to those in FIG.

The sensor unit 30 includes a unit housing 31, a resist roller pair 13, a CIS carriage 35, and a carriage moving mechanism 50. The unit housing 31 rotatably supports the resist roller pair 13 and movably supports the CIS carriage 35 in the paper width direction (arrow AA'direction). At the upstream end of the unit housing 31 with respect to the paper transport direction (arrow B direction), a resist entry guide 33 for guiding the paper P to the nip portion of the resist roller pair 13 is provided.

As shown in FIG. 4, the unit housing 31 has side frames 31a and 31b arranged on the front side and the back side of the printer 100, respectively, and a connecting frame 31c connected to the side frames 31a and 31b 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 with each other.

The CIS carriage 35 is arranged adjacent to the downstream side (left side in FIG. 3) of the resist roller pair 13 with respect to the paper transport direction (arrow B direction). The CIS carriage 35 has a carriage body 37 (see FIG. 6) in which the CIS 40 and the light source unit 41 are housed. The CIS 40 and the light source unit 41 are housed in the lower and upper parts of the carriage body 37, respectively, and two contact glasses 42a and 42b are arranged to face each other between the CIS 40 and the light source unit 41. A part of the paper transport 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 in the width direction of the paper P based on the difference in light intensity between the portion where the light from the light source unit 41 is incident and the portion blocked by the paper P. The light source unit 41 has an LED 41a arranged at one end in the paper width direction, and a light guide plate 41b that diffuses the light emitted from the LED 41a over the entire area in 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 show an upper surface of the CIS 40 mounted on the carriage body 37, respectively. It is a perspective view seen from the side and the lower surface side.

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

In the CIS 40, a large number of detection units 43 composed of photoelectric conversion elements are arranged in the paper width direction (left-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 (opposite side of the detection unit 43) of the CIS board 45.

FIG. 9 is a block diagram showing a control path of the printer 100 of the present embodiment. The CPU 70 controls the entire printer 100 in an integrated manner. When the printer 100 starts the printing operation on the paper P in response to the print data received from the external computer or the like, the CPU 70 makes various settings for reading the signal 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 a reference clock signal for reading a signal from the CIS 40 and a storage time determination signal for determining the charge storage time in the CIS 40 to 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 the 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. Further, 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.

When the standby paper P is conveyed toward the recording unit 9 (see FIG. 1) by the resist roller pair 13 (see FIG. 3), the CPU 70 instructs the CIS control circuit 71 to detect the edge position. 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 storage time determination signal. The LED drive circuit 73 lights the LED 41a for a certain period of time according to the control signal from the CIS control circuit 71.

The CIS 40 uses the next storage time determination signal and the reference clock signal to apply a voltage corresponding to the amount of light stored in each pixel (photoelectric conversion element) of the pixel group of the detection unit 43 while the LED 41a is lit, one pixel at a time. Output as an output signal. The output signal output from the CIS 40 is binarized by comparison with the comparison reference voltage (threshold voltage) in the binarization circuit 75, and is input to the CIS control circuit 71 as a digital signal.

The CIS control circuit 71 sequentially confirms the 0/1 value of the binarized digital signal in the binarization circuit 75 one pixel at a time for each of the output signals output by the CIS 40. Then, the CIS control circuit 71 detects the position of the pixel (position of the photoelectric conversion element) of the detection unit 43 in which the value of the digital signal switches from 0 to 1 or from 1 to 0.

When the CIS control circuit 71 detects the position of the pixel whose digital signal value has been switched, the position of the switched pixel is determined to be the edge position in the width direction of the paper P. The CPU 70 has an edge position determined by the CIS control circuit 71 and an edge position (reference edge position) when the paper P is conveyed at an ideal transfer position (reference transfer position) where the paper P passes through the center position of the paper passing area. Calculate the amount of deviation from. 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 ejection nozzles of the line heads 10C to 10K in the recording unit 9 according to the amount of deviation in the width direction of the transmitted paper P.

Next, the moving mechanism of the CIS carriage 35 in the sensor unit 30 of the present 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 from below, and FIG. 12 is a carriage moving. It is a perspective view of the mechanism 50 and is the figure which includes the cross section along the rotation axis of the two-step 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 (first gear) 55a and a large diameter portion (second gear) 55b, and the small diameter portion 55a meshes with the worm gear 53. As shown in FIG. 12, a torque limiter 65 is built in the two-stage gear 55, and 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 become independent. It is rotatable.

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

As the rack 57 moves, the light-shielding plates 61a and 61b shield the detection unit 63a of the PI sensor 63 from light, so that the light-receiving signal level changes from HIGH to LOW. Further, when the light-shielding plates 61a and 61b are retracted from the detection unit 63a, the light-receiving signal level changes from LOW to HIGH. The light receiving 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 of the front side (arrow A direction) 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 as shown in FIG. 13, it is fixed to the CIS carriage 35 by fastening the screw 66 to the screw fixing hole 60b.

As shown in FIG. 14, a circular engaging hole 60a to which the engaging projection 57b of the rack 57 is engaged is formed at one end of the connecting plate 60. The inner diameter of the engaging hole 60a is formed to be slightly larger than the outer diameter of the engaging projection 57b. An elongated screw fixing hole 60b extending in the transport direction (arrow B direction) is formed at the other end of the connecting plate 60.

By making the screw fixing hole 60b an elongated hole, 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 transport direction (sub-scanning direction) can be adjusted within the range of the screw fixing hole 60b. Even so, by adjusting the fixing position of the connecting plate 60, the engaging projection 57b of the rack 57 and the engaging hole 60a of the connecting plate 60 can be reliably engaged with each other.

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

On the other hand, as shown in FIG. 16, the engaging projection 57b of the rack 57 projects from the lower surface of the rack 57 toward the upstream side in the transport direction at an angle θ1. As a result, the protruding direction of the engaging projection 57b becomes substantially perpendicular to the opening surface O of the engaging hole 60a, so that the engaging projection 57b and the engaging hole 60a engage with each other when the CIS carriage 35 reciprocates. Is hard 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, by rotating the CIS drive motor 51 in a predetermined direction, the rack 57 is moved in the direction of arrow A 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 arrow A while sliding along the shaft 47.

FIG. 17 is a partial perspective view of the end portion of the carriage body 37 on the front side (direction of arrow A), and FIG. 18 is a state in which the CIS carriage 35 is moved toward the front side (direction of arrow A) of the sensor unit 30. It is a partial cross-sectional view of the front side end portion. As shown in FIG. 17, the contact surface 37c protrudes most in the direction of arrow A on the front side of the carriage body 37. Therefore, when the CIS carriage 35 moves in the direction of arrow A by a predetermined distance, the contact surface 37c of the carriage body 37 comes into contact with 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 arranged at the position moved to the frontmost side (home position, first position). As a result, 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, when the paper size information is a large size exceeding the A3 size, the CIS carriage 35 is moved to the back side (arrow A'direction) of the printer 100. Specifically, by rotating the CIS drive motor 51 in the opposite 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 arrow A'while sliding along the shaft 47.

FIG. 19 is a partial perspective view of the end portion of the carriage body 37 on the back side (direction of arrow A'), and FIG. 20 is a sensor unit showing a state in which the CIS carriage 35 is moved toward the back side (direction of arrow A'). It is a partial cross-sectional view of the back side end portion of 30. As shown in FIG. 19, the contact surface 37d protrudes most in the arrow A'direction on the back surface side of the carriage body 37. Therefore, when the CIS carriage 35 moves in the direction of arrow A'by a predetermined distance, the contact surface 37d of the carriage body 37 comes into contact with the inner surface of the side frame 31b of the unit housing 31, as shown in FIG. At this time, the CIS carriage 35 is arranged at the position (second position) moved to the rearmost side. As a result, 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 certain period of time after the contact surfaces 37c and 37d of the carriage body 37 come into contact with the inner surfaces of the side frames 31a and 31b. Further, the rotational torque of the torque limiter 65 is set to be 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 surface frames 31a and 31b.

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

According to the present embodiment, the CIS carriage 35 is positioned at the first position and the second position by contacting the contact surfaces 37c and 37d of the carriage body 37 with the inner surfaces of the side frames 31a and 31b of the unit housing 31. Will be done. Therefore, 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 with respect to the side frames 31a and 31b can be stabilized by utilizing 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, backlash of the worm gear 53, the two-stage gear 55, and the rack 57 can be prevented, and the position 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 comes into contact with 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 received signal level of the PI sensor 63 switches between LOW and HIGH to LOW. When the CPU 70 (see FIG. 9) detects this change in the received signal level, it is determined that the CIS carriage 35 has normally reciprocated.

If the light receiving 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. An error is displayed on the 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, one PI sensor 63 can be used to detect malfunction of the reciprocating movement between the first position and the second position of the CIS carriage 35. Therefore, the number of sensors can be reduced as compared with the configuration in which separate sensors are arranged at the first position and the second position to detect the malfunction.

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

The FFC 67 is a ribbon-shaped wiring cable in which a plurality of conductive wires are arranged in parallel with each other in a covering member. Since the FFC 67 has excellent flexibility and can be bent into any 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 side connector 46 of the CIS 40. It is connected to (see FIG. 8).

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

FIG. 23 is a partial cross-sectional view taken along the longitudinal direction around the end portion on the back surface side of the sensor unit 30. FIG. 23 shows a state in which the CIS carriage 35 is in the process of moving from the first position to the second position, and the FFC 67 pulled 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, since the CIS carriage 35 slides between the first position and the second position along the two shafts 47, the CIS carriage 35 is stable without rattling. Move back and forth. As a result, no extra load is applied to the FFC 67 connected to the CIS carriage 35 during the reciprocating movement of the CIS carriage 35, and damage to the FFC 67 can be suppressed.

Further, since the cable insertion hole 32 for pulling out the FFC 67 to the outside of the unit housing 31 and the cable guide hole 37e for pulling out 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 on the outside of the side frame 31b. Can bend in the direction. As a result, it is possible to suppress twisting or bending of the FFC 67 due to the reciprocating movement of the CIS carriage 35, and it is possible to suppress disconnection of the FFC 67.

Others The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, an example using a transmissive type CIS40 provided with a detection unit 43 for receiving laser light from the light source unit 41 is shown, but for example, a light emitting unit for emitting light to paper P is provided for detection. Using a reflective CIS40 that detects the reflected light from the paper P in the unit 43, the edge position of the paper P is determined by the intensity difference between the reflected light from the paper P and the reflected light from the non-passing region of the paper P. You can also. In this case, a color different from the color (white) of the paper P is located at a position facing the detection unit 43 of the CIS 40 so that the intensity difference between the reflected light from the paper P and the reflected light from the non-passing region of the paper P becomes large. It is preferable to arrange the background member of.

Further, in the above embodiment, the example in which CIS40 is used as the sensor for detecting the edge position of the paper P is shown, but a sensor other than CIS such as CCD may be used.

Further, in the above embodiment, the inkjet recording type printer 100 that ejects ink from the ink ejection nozzles of the line heads 10C to 10K onto the paper P to record an image has been described as an example, but the present invention has been described with reference to the inkjet recording. Not limited to the printer 100 of the type, an electrostatic latent image is formed by irradiating an image carrier such as a photoconductor drum with a laser, and toner is adhered to the electrostatic latent image to form a toner image, and then the toner is formed. It can also be applied to an electrophotographic image forming apparatus that transfers an image onto a paper (recording medium) and heats and pressurizes the transferred unfixed toner to form a permanent image.

5 First belt transport section (transport section)
9 Recording unit (image forming unit)
13 Resist roller vs. 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 part 43 Detection part 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 Connecting plate (connecting part)
60a Engagement hole 60b Screw fixing hole 61a, 61b Shading plate 63 PI sensor 63a Detection unit 65 Torque limiter 67 FFC (flexible flat cable)
100 printer (image forming device)
P paper (recording medium)
O opening surface

Claims (7)

An edge detection sensor that is placed in the transport section that transports the sheet and detects the edge position of the sheet in the sheet width direction that is orthogonal to the sheet transport direction.
The unit housing that houses the edge detection sensor and
In the sensor unit equipped with
A sensor carriage on which the edge detection sensor is mounted and supported so as to be reciprocally movable in the seat width direction with respect to the unit housing.
A carriage moving mechanism for reciprocating the sensor carriage in the seat width direction is provided.
The sensor carriage is selectively positioned at a first position in contact with one end side in the seat width direction of the unit housing and a second position in contact with the other end side in the seat width direction.
The carriage movement mechanism is
It has a motor and a drive transmission gear train that includes a plurality of gears that transmit the driving force of the motor to the sensor carriage.
The motor continues to be driven for a predetermined time even after the sensor carriage has moved to the first position or the second position.
One of the gears connects the first gear and the second gear coaxially arranged, the first gear and the second gear, and a rotational load applied to the first gear and the second gear is applied. A sensor unit including a torque limiter that disconnects the first gear and the second gear only when the value exceeds a predetermined value. The drive transmission gear train is
A drive output gear that is fixed to the rotating shaft of the motor and meshes with the first gear,
A rack in which rack teeth that mesh with the second gear are formed, connected to the sensor carriage, and reciprocated together with the sensor carriage.
The sensor unit according to claim 1, wherein the sensor unit has. The rack is provided with two light-shielding plates that switch the detection unit of one unit position detection sensor provided in the unit housing between a light-shielding state and a light-transmitting state.
One of the light-shielding plates switches the detection unit from the translucent state to the light-shielding state to detect that the sensor carriage has moved to the first position, and the other of the light-shielding plates detects the detection unit. The sensor unit according to claim 2, wherein the sensor carriage detects that the sensor carriage has moved to the second position by switching from the translucent state to the light-shielding state. The sensor carriage has a carriage body on which the edge detection sensor is mounted, and a connecting plate that connects the carriage body and the rack.
The rack is provided with an engaging protrusion that engages with an engaging hole provided in the connecting plate.
The connecting plate is arranged so as to be inclined in the sheet transport direction with respect to the rack.
The sensor unit according to claim 2 or 3, wherein the engaging protrusion projects substantially perpendicular to the opening surface of the engaging hole. The engagement hole is formed on one end side of the connecting plate, and a screw fixing hole for fixing the connecting plate and the carriage body with screws is formed on the other end side of the connecting plate.
The sensor unit according to claim 4, wherein the screw fixing hole has an elongated hole shape extending in the sheet transport direction. The edge detection sensor is a contact image sensor having a plurality of photoelectric conversion elements arranged along the sheet width direction.
The invention according to any one of claims 1 to 5, wherein the pixel position where the value of the digital signal obtained by binarizing the output signal of the contact image sensor is switched is determined as the edge position in the width direction of the recording medium. Sensor unit. The transport unit that transports the sheet and
An image forming unit that forms an image on the sheet conveyed by the conveying unit, and an image forming unit.
The sensor unit according to any one of claims 1 to 6, which is arranged on the upstream side of the image forming unit with respect to the sheet transport direction.
A control unit that corrects an image formation position in the sheet width direction by the image forming unit based on an edge position in the sheet width direction orthogonal to the sheet transport direction of the sheet detected by the sensor unit.
An image forming apparatus equipped with.

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