JP2021006483A - Image forming device - Google Patents

Abstract

To provide an image forming device that can accurately detect an edge of a sheet by an edge detection sensor without cleaning sheet dust, when the sheet dust accumulates on a surface of a contact glass corresponding to a widthwise edge of the sheet.SOLUTION: An image forming device includes: a carriage 35 that holds an edge detection sensor 40 and a contact glass 42a and is movable in a transport width direction orthogonal to a sheet transport direction; a carriage drive mechanism; and a control unit. The control unit includes a sheet number counting unit that counts a cumulative number of sheets P of the same size that have passed over the contact glass 42a, with a position of the carriage 35 in the transport width direction fixed at a predetermined position, and the carriage drive mechanism moves the carriage 35 to a position different from a current position when the number of sheets counted by the sheet number counting unit reaches a predetermined number.SELECTED DRAWING: Figure 16

Description

The present invention relates to an image forming apparatus.

In an image forming apparatus that forms an image on paper transported along a paper transport path, if the paper is misaligned in the width direction (direction orthogonal to the transport direction), it may lead to misalignment of the image.

In order to avoid this problem, for example, in the image forming apparatus shown in Patent Document 1, a contact image sensor (CIS) for detecting the edge position of the paper is provided on the back surface side of the contact glass arranged facing the paper transport path. It is provided so that the amount of misalignment in the width direction of the paper is calculated based on the edge position detected by CIS. When forming an image, the image forming position is adjusted according to the calculated amount of misalignment of the paper.

Japanese Unexamined Patent Publication No. 2003-327345

In the image forming apparatus shown in Patent Document 1, when paper of the same size is repeatedly passed, paper dust is deposited on the surface of the contact glass where the edge of the paper (edge in the width direction) passes. For this reason, there is a problem that the translucency of the portion of the contact glass where the paper dust is accumulated is lowered, and the edge detection accuracy of the paper by the CIS (edge detection sensor) is lowered.

In order to avoid this problem, it is conceivable to clean the surface of the contact glass automatically or manually. However, cleaning takes several tens of seconds even if it is performed automatically, and it takes several minutes if it is performed manually. Since it is necessary to stop the printing operation of the image forming apparatus during this cleaning, there is room for improvement from the viewpoint of improving the printing efficiency.

The present invention has been made in view of this point, and an object of the present invention is to clean the paper dust when the paper dust accumulates on the surface of the contact glass corresponding to the edge of the paper in the width direction. An object of the present invention is to provide an image forming apparatus capable of accurately detecting the edge of paper by an edge detection sensor without performing work.

The image forming apparatus according to the present invention includes an image recording unit that records an image on paper transported along a paper transport path, contact glass arranged facing the paper transport path, and the paper of the contact glass. It is provided on the side opposite to the transport path side, and is provided with an edge detection sensor that detects an edge in the width direction of the paper by receiving light transmitted through the contact glass.

The image forming apparatus includes a carriage that holds the edge detection sensor and the contact glass and is movable in the transport width direction orthogonal to the paper transport direction, and a carriage drive that drives the carriage in the transport width direction. A mechanism and a control unit for controlling the carriage drive mechanism are further provided, and the control unit is a sheet of paper of the same size that has passed over the contact glass in a state where the position of the carriage in the transport width direction is the same. It has a number counting unit that counts the cumulative number of sheets, and when the number of sheets counted by the number counting unit reaches a predetermined number, the carriage is driven by the carriage drive mechanism to position the carriage in the transport width direction. It is configured to change to a position different from the current position.

According to the present invention, when paper dust accumulates on the surface of the contact glass corresponding to the edge in the width direction of the paper, the edge detection of the paper by the edge detection sensor is accurate without cleaning the paper dust. You can do it well.

FIG. 1 is a side sectional view showing a schematic structure of a printer provided with a sensor unit according to an embodiment of the present invention. FIG. 2 is an external perspective view of the sensor unit of the present embodiment mounted on the printer. FIG. 3 is a side sectional view of the sensor unit. FIG. 4 is a perspective view of a frame constituting the unit housing of the sensor unit. FIG. 5 is an external perspective view of the CIS carriage. FIG. 6 is a perspective view of the CIS mounted on the CIS carriage as viewed from the upper surface side. FIG. 7 is a perspective view of the CIS mounted on the CIS carriage as viewed from the lower surface side. FIG. 8 is an enlarged perspective view showing the periphery of the carriage drive mechanism in an enlarged manner. FIG. 9 is a schematic plan view showing a state in which the CIS carriage is in the first position. FIG. 10 is a schematic plan view showing a state in which the CIS carriage is in the second position. FIG. 11 is a block diagram showing a part of the control system of the printer. FIG. 12 is a diagram showing an example of target position data of the CIS carriage stored in the storage unit. FIG. 13 is a flowchart showing a part of the drive control of the CIS carriage. FIG. 14 is a flowchart showing the remaining part of the movement control of the CIS carriage. FIG. 15 is a schematic view showing an example of an error display screen. FIG. 16 is a schematic plan view showing an example of correcting the target position of the CIS carriage when the paper size is a standard size. FIG. 17 is a schematic plan view showing an example of correcting the target position of the CIS carriage when the paper size is a large size.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments.

FIG. 1 is a side sectional view showing a schematic structure of an inkjet recording type printer 100 including the sensor unit 30 in the embodiment. In the following description, the front side, the rear side, the left side, and the right side are directions with reference to the printer 100, respectively.

As shown in FIG. 1, the printer 100 has a substantially rectangular parallelepiped housing 1. A paper cassette 2a is provided below the inside of the housing 1, and an image recording unit 3 is provided above the paper cassette 2a to eject ink onto the paper P and record an image. A manual paper feed tray 2b is provided on the right side surface of the housing 1, and a paper ejection tray 4 is provided on the left side surface of the housing 1.

In the housing 1, the first paper transport path T1 that supplies the paper P set in the paper feed cassette 2a to the image recording unit 3 and the paper P set in the manual paper feed tray 2b are stored in the image recording unit 3. A second paper transport path T2 is provided, and a third paper transport path T3 that guides the paper P that has passed through the image recording unit 3 to the paper discharge tray 4 is provided. A loop-shaped inverted transport path T5 is connected in the middle of the third paper transport path T3 via a branch transport path T4. The first paper transport path T1, the second paper transport path T2, and the reverse transport path T5 merge on the upstream side of the image recording unit 3 in the paper transport direction. A fourth paper transport path T6 is provided between the merging unit and the image recording unit 3. A sensor unit 30 for detecting the edge position in the width direction of the paper P is provided at the upstream end of the fourth paper transport path T6 (near the downstream side of the confluence in the paper transport direction). A first belt transport unit 5 and an image recording unit 3 are arranged in the vicinity of the downstream side of the sensor unit 30.

The sensor unit 30 is provided with a pair of resist rollers 13. The resist roller pair 13 measures the timing of the ink ejection operation executed by the image recording unit 3 while correcting the oblique 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. A large number of air suction holes (not shown) are formed in the first transport belt 8. The paper P sent out from the resist roller pair 13 passes under the image recording unit 3 in a state of being attracted and held by the first transfer belt 8 by the paper suction unit 20 provided inside the first transfer belt 8.

The image recording unit 3 includes line heads 10C, 10M, 10Y and 10K. The line heads 10C to 10K record an image on the paper P which is sucked 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 each ink from each line head 10C to 10K toward the paper P adsorbed on the first transport belt 8, four colors of 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 in the paper transport direction. The second belt transport unit 11 transports the paper P while adsorbing and holding the paper P in the same configuration as the first belt transport unit 5. The ink discharged on the surface of the paper P is dried while the paper P passes through the second belt transport unit 11. The paper P that has passed through the second belt transport portion 11 is supplied to the decaler portion 14 provided at the lower end of the third paper transport path T3, and the curl generated on the paper P is corrected.

The paper P that has passed through the decaler section 14 passes through the third paper transport path T3 and is discharged to the paper ejection tray 4 when double-sided recording is not performed. When recording is performed on both sides of the paper P, the paper P that has passed through the decaler section 14 after the image recording on one side is completed is conveyed to the reverse transfer path T5 through the branch transfer path T4. The paper P sent to the reverse transport path T5 is switched in the transport direction in order to reverse the front and back, passes through the upper part of the printer 100, and is transported to the resist roller pair 13. The paper P transported to the resist roller pair 13 is transported to the first belt transport unit 5 again with the side on which the image is not recorded facing upward. Reference numeral 15 in FIG. 1 is a maintenance unit that moves below the image recording unit 3 when performing maintenance and collects the ink ejected (purged) from the ink ejection nozzle.

[Details of sensor unit 30]
Next, the detailed structure of the sensor unit 30 will be described. FIG. 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.

The sensor unit 30 includes a unit housing 31, a resist roller pair 13, a CIS carriage 35, and a carriage drive mechanism 50. The unit housing 31 rotatably supports the resist roller pair 13 and movably supports the CIS carriage 35 in the transport width direction. At the upstream end of the unit housing 31 with respect to the paper transport 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 a pair of side frames 31a and 31b facing each other in the front-rear direction of the printer 100, and a connecting frame 31c connected to the pair of side frames 31a and 31b in a bridging manner. .. Between the pair of 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. The CIS carriage 35 has a carriage body 37 (see FIG. 5) in which the CIS 40 (edge detection sensor) 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 fourth paper transport path T6 is formed by the upper surface of the contact glass 42a (see FIG. 3) and the lower surface of the contact glass 42b.

The CIS 40 detects an edge 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 transport width direction, and a light guide plate 41b that diffuses the light emitted from the LED 41a over the entire transport width direction and guides the light to the CIS 40.

FIG. 5 is an external perspective view of the CIS carriage 35, and FIGS. 6 and 7 are perspective views of the CIS 40 mounted on the carriage body 37 as viewed from the upper surface side and the lower surface side, respectively.

The carriage body 37 has a CIS storage portion 37a (see FIG. 5) 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 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 transport width direction (left-right direction in FIG. 6). 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 an FFC (not shown) is connected is provided on the lower surface side (opposite side of the detection unit 43) of the CIS board 45.

[Structure of Carriage Drive Mechanism 50]
Next, the carriage drive mechanism 50 for driving the CIS carriage 35 will be described. FIG. 8 is an enlarged perspective view showing the periphery of the carriage drive mechanism 50 in an enlarged manner.

The carriage drive 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 the small diameter portion 55a meshes with the worm gear 53. The two-stage gear 55 has a built-in torque limiter (not shown), 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 can rotate independently. ing.

The rack 57 has rack teeth 57a that mesh with the large diameter portion 55b of the two-stage gear 55. The rack 57 is connected to the CIS carriage 35 via a connecting plate 60. When the CIS drive motor 51 is rotationally driven, the rotational movement of the worm gear 53 is transmitted to the rack 57 via the two-stage gear 55, and the rack 57 linearly moves together with the CIS carriage 35 in the transport width direction (front-rear direction). There is. The CIS carriage 35 is configured to be reciprocally movable between the first position and the second position in the transport width direction. In the first position, the front end surface of the CIS carriage 35 abuts on the front side frame 31b of the unit housing 31, and in the second position, the rear end surface of the CIS carriage 35 abuts on the rear side frame 31a of the unit housing 31. Get in touch.

In the present embodiment, only for a certain period of time after the rear end surface and the front end surface of the CIS carriage 35 come into contact with the inner surfaces of the side frame 31a and 31b (that is, after the CIS carriage 35 reaches the first position and the second position). The rotation of the CIS drive motor 51 is continued. Further, the operating torque of the torque limiter is set to be smaller than the torque applied to the two-stage gear 55 when the CIS drive motor 51 rotates with the rear end surface and the front end surface of the carriage body 37 in contact with the side frames 31a and 31b. ing. As a result, after the rear end surface and the front end surface of the carriage body 37 come into contact with the inner surfaces of the side frames 31a and 31b of the unit housing 31 (after the CIS carriage 35 reaches the first and second positions), the CIS drive motor The small diameter portion 55a and the large diameter portion 55b of the two-stage gear 55 rotate independently until the 51 stops.

FIG. 9 is a schematic plan view showing a state in which the CIS carriage 35 is in the first position, and FIG. 10 is a schematic plan view showing a state in which the CIS carriage 35 is in the second position.

As shown in FIGS. 9 and 10, on the side surface of the rack 57, a first light-shielding plate 61a and a second light-shielding plate 61b that are arranged at intervals in the front-rear direction, which is the moving direction of the rack 57, are projected. The light-shielding plates 61a and 61b are arranged so as to pass through the detection unit (between the light emitting element and the light receiving element) of the PI (photo interrupter) sensor 62. The PI sensor 62 is fixed to the unit housing 31 via a stay 63 (see FIG. 8).

In the state where the CIS carriage 35 is in the first position (state in FIG. 9), the detection unit of the PI sensor 62 is shielded from light by the first shading plate 61a, and the CIS carriage 35 is in the second position (state in FIG. 10). Then, the detection unit of the PI sensor 62 is shielded from light by the second light-shielding plate 61b. When the detection unit of the PI sensor 62 is shielded from light by the light-shielding plates 61a and 61b, the light-receiving signal level changes from HIGH to LOW. Further, the light receiving signal level changes from LOW to HIGH when the light shielding plates 61a and 61b are retracted from the detection unit. The received signal of the detection unit is transmitted to the control unit 200 (see FIG. 11). The control unit 200 detects that the CIS carriage 35 has reached the first position or the second position based on the change in the received signal level of the PI sensor 62.

[Configuration of control system of printer 100]
FIG. 11 is a block diagram showing a part of the control system of the printer 100. The control unit 200 is composed of a microcomputer having a CPU, a ROM, a RAM, and the like.

The control unit 200 is a CIS drive for moving the PI sensor 62 that detects the moving end (first position or the second position) of the CIS carriage 35, the LED 41a of the light source unit 41, and the CIS carriage 35 to the target position. The motor 51, the CIS control circuit 70 that detects the edge position of the paper P based on the output signal from the CIS 40, the storage unit 71 that stores various data, and the operation panel 72 are connected via a signal line. .. The operation panel 72 has a display unit 72a for displaying various information and an operation unit 72b for performing various settings by the user operating with a finger.

The control unit 200 has a number counting unit 201, a misalignment detecting unit 202, an image position adjusting unit 203, and a CIS target position correction unit 204.

The number counting unit 201 counts the number of sheets of paper P that have passed over the contact glass 42a with the CIS carriage 35 at the same position. The number-of-sheet counting unit 201 counts the number of sheets for each of the printable paper sizes (in this embodiment, A3 size to A5 size and two types of sizes larger than A3 size (hereinafter referred to as L1 size and L2 size)). .. The number of sheets may be counted, for example, based on a detection signal from a paper detection sensor arranged on the downstream side of the contact glass 42a, or may be determined by software based on the processing status of print data. When the target position of the CIS carriage 35 when using the standard size paper P is corrected by the CIS target position correction unit 204 described later, the number counting unit 201 resets all the count sheets of the standard size to 0. Then, when the target position of the CIS carriage 35 when using the large size paper P is corrected by the CIS target position correction unit 204, all the count sheets of the large size are reset to 0.

The misalignment detection unit 202 detects the amount of misalignment in the width direction of the paper P that has passed through the resist roller pair 13 based on the signal received from the CIS 40 via the CIS control circuit 70.
Specifically, when the printing operation starts, the misalignment detection unit 202 transmits a control signal to the CIS drive motor 51 to move the CIS carriage 35 in the sensor unit 30 to the target position. This target position is stored in, for example, a storage unit 71 in a data format. The target position in the storage unit 71 is corrected and rewritten at a predetermined timing by the CIS target position correction unit 204 described later. Details of the correction process by the CIS target position correction unit 204 will be described later.

After moving the CIS carriage 35 to the target position, the misalignment detection unit 202 lights the LED 41a of the light source unit 41 with a predetermined amount of light for a certain period of time. 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 lit, one pixel at a time by the next storage time determination signal and the reference clock signal. Output as an output signal. The output signals output from the CIS 40 are binarized by comparison with the comparison reference voltage (threshold voltage) in the binarization circuit (not shown), and are input to the CIS control circuit 70 as digital signals. The CIS control circuit 70 sequentially confirms the value of 0/1 of the digital signal binarized in the binarization circuit for each output signal output by the CIS 40, pixel by pixel. Then, the CIS control circuit 70 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 changes from 0 to 1 or from 1 to 0. When the CIS control circuit 70 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 (hereinafter, simply referred to as the edge position of the paper P).

The misalignment detection unit 202 is conveyed at the edge position in the width direction of the paper P determined by the CIS control circuit 70 and the ideal transfer position (reference transfer position) at which the sheet P passes through the center position of the paper passing area. The amount of deviation from the edge position (reference edge position) is calculated.

The image position adjusting unit 203 shifts the use area of the ink ejection nozzle of the line heads 10C to 10K based on the deviation amount calculated by the position deviation detecting unit 202. As a result, the image position adjusting unit 203 makes the central position of the image forming region of the paper P in the width direction coincide with the center position in the width direction of the paper P.

The CIS target position correction unit 204 corrects the target position of the CIS carriage 35 stored in the storage unit 71. FIG. 12 is an initial value of the target position data of the CIS carriage 35 stored in the storage unit 71. The target position of the CIS carriage 35 is set to a different position depending on whether the paper size for printing is a standard size or a large size. In the case of the standard size, the target position of the CIS carriage 35 is set to the first position (position in FIG. 9), and in the case of the large size, the target position of the CIS carriage 35 is set to the second position (position in FIG. 10). There is. When the CIS carriage 35 is in the first position, both ends of the standard size paper P can be detected by the CIS 40, but the edge position of the large size paper P is out of the reading range of the CIS 40. Therefore, for the large size paper P, by setting the target position of the CIS carriage 35 to the second position (see FIG. 10), one edge (front edge) of the paper P can be detected by the CIS 40. .. When the paper size is large, the misalignment detection unit 202 determines the amount of misalignment in the width direction of the paper P in consideration of one edge position of the paper P received from the CIS 40 and the paper size information included in the print data. To detect.

The CIS target position correction unit 204 corrects the target position of the CIS carriage 35 stored in the storage unit 71 based on the paper size information included in the print data and the information from the number counting unit 201.

Specifically, the CIS target position correction unit 204 specifies the paper size to be printed based on the paper size information included in the print data, and the specified paper size is based on the information from the number counting unit 201. The count number of sheets P (the number of sheets that have passed through the contact glass 42a) is acquired. Then, when the acquired count number reaches a predetermined number, the CIS target position correction unit 204 corrects the target position of the CIS carriage 35 corresponding to the paper size to a position separated by a predetermined amount δ inside in the transport width direction. To do. The predetermined number of sheets is, for example, a limit number of sheets on the surface of the contact glass 42a in which the edge detection accuracy of the paper P by the CIS 40 decreases below the target accuracy due to the accumulation of paper dust at a portion corresponding to the edge position in the width direction of the paper P ( For example, the number of sheets may be set to the same as or slightly smaller than the number of sheets (10,000 to 15,000). The predetermined number of sheets is stored in the storage unit 71 in the present embodiment, and can be changed by the user operating the operation panel 72 of the printer 100. The predetermined number of sheets may be an immutable constant stored in a ROM or the like.

FIG. 12 is a flowchart showing an example of carriage drive control including the target position correction process of the CIS carriage 35 described above. The processing of each of the following steps is realized by the cooperation between the software and the hardware when the control unit 200 executes the program stored in the ROM.

In step S1, the size of the paper P to be printed is specified based on the paper size information included in the print data received from the external computer or the like.

In step S2, the number of sheets counted by the number counting unit 201 for the paper P of the paper size specified in step S1 is acquired.

In step S3, it is determined whether or not the number of counts acquired in step S2 has reached the predetermined number stored in the storage unit 71, and if this determination is NO, the process proceeds to step S9, while YES. If, the process proceeds to step S4.

In step S4, it is determined whether or not the paper size specified in step S2 is a standard size (A3, A4 or A5 in this embodiment), and if this determination is NO, the process proceeds to step S10, while YES. If, the process proceeds to step S5.

In step S5, the target position of the CIS carriage 35 when the standard size paper P is used is corrected to a position separated by a predetermined amount δ inside the current target position in the transport width direction, and stored in the storage unit 71. The stored target position data is rewritten to the corrected position.

In step S6, the number of counts counted by the number counting unit 201 for all of the standard sizes A3, A4, and A5 is reset to 0.

In step S7, it is determined whether or not the corrected target position of the CIS carriage 35 is a position where the edge of the paper P can be detected by the CIS 40. If this determination is NO, the process proceeds to step S12, while if YES, the process proceeds to step S8.

In step S8, the CIS drive motor 51 moves the CIS carriage 35 to the corrected target position. In this movement, the CIS carriage 35 is once moved to the original position and then moved to the target position. The original position of the CIS carriage 35 depends on the size of the paper P to be printed. The original position when the paper size is a standard size is the first position, and the original position when the paper size is a large size is the second position. The original position of the CIS carriage 35 may be fixed (for example, the first position) regardless of the paper size.

In step S9, which proceeds when the determination in step S3 is NO, the CIS carriage 35 is moved to the current target position by controlling the CIS drive motor 51.

In step S10, which proceeds when the determination in step S4 is NO, the target position of the CIS carriage 35 when using the large size paper P is separated from the current target position by a predetermined amount δ inside the transport width direction. The target position data stored in the storage unit 71 is rewritten to the corrected position by correcting the position.

In step S11, the number of sheets counted by the number counting unit 201 for the large sizes L1 and L2 is reset to 0.

In step S12, which proceeds when the determination in step S7 is NO, an error screen 300 is displayed on the display unit 72a (an example of the notification unit) of the operation panel 72 of the printer 100 to prompt the cleaning of the contact glass 42a. FIG. 15 shows an example of the error screen 300. On the error screen 300, the message 301 "Please clean the contact glass of the sensor unit by wiping it off" and the cleaning completion button 302 for the user to proceed to the next operation after completing the cleaning are displayed. To.

In step S13, it is determined whether or not the cleaning completion button 302 is pressed on the error screen 300 displayed in step S12. If this determination is NO, the screen display in step S12 is continued, and if YES. Proceeds to step S14.

In step S14, the target position of the CIS carriage 35 stored in the storage unit 71 is returned to the initial value (see FIG. 12).

In step S15, the number of sheets counted by the number counting unit 201 for all paper sizes (A3 to A5 size and L1 to L2 size) including the standard size and the large size is reset to 0, and then returned.

FIG. 16 shows how the position of the CIS carriage 35 is changed by executing the carriage drive control by the control unit 200 when the standard size paper P is used. In the initial state, the CIS carriage 35 is in the first position (see FIG. 9), but thereafter, every time the number of sheets counted by the number counting unit 201 reaches a predetermined number for any one of the standard sizes A3 to A5. The control unit 200 executes the processes from step S5 to step S8, and the CIS carriage 35 moves inward in the transport width direction (rear side of the printer 100) by a predetermined amount δ (see FIGS. 16A to 16C). ).

FIG. 17 shows how the position of the CIS carriage 35 is changed by executing the carriage drive control by the control unit 200 when the standard size paper P is used. In the initial state, the CIS carriage 35 is in the first position (see FIG. 10), but thereafter, it is controlled every time the number of sheets counted by the number counting unit 201 reaches a predetermined number for either the large size L1 or L2 size. The process from step S10 to step S8 is executed by the unit 200, and the CIS carriage 35 moves inward in the transport width direction (front side of the printer 100) by a predetermined amount δ (see FIGS. 17A to 17C). Here, in the example of FIG. 17, when the position correction is performed for the third time, the rear edge position of the L1 size paper P substantially overlaps the rear edge of the CIS 40 (the rear edge of the readable range). The front edge position is located considerably in front of the front edge of the CIS 40. Therefore, if the fourth position correction is performed, the front and rear edges of the L1 size paper P pass outside the reading range of the CIS 40. Therefore, even if the fourth position correction is required, it is determined that the edge detection of the paper P is impossible in the process of step S7 (NO in step S7), and an error occurs in the display unit 72a of the operation panel 72. The screen 300 is displayed (step S12).

[Action effect]
As described above, the printer 100 of the present embodiment has a CIS carriage 35 configured to hold the CIS 40 and the contact glass 42a and be movable in the transport width direction, and a carriage drive mechanism for driving the CIS carriage 35 in the transport width direction. 50 and a control unit 200 are provided. The control unit 200 has a number counting unit 201 that counts the cumulative number of sheets P of the same size that have passed over the contact glass 42a with the CIS carriage 35 in the same position in the transport width direction. When the number of sheets counted by the number counting unit 201 reaches a predetermined number, the carriage drive mechanism 50 drives the CIS carriage 35 to change the position of the CIS carriage 35 in the transport width direction to a position different from the current position. Has been done.

According to this configuration, when a predetermined amount or more of paper dust is deposited on the surface of the contact glass 42a at a position corresponding to the edge of the paper P in the width direction, the carriage drive mechanism 50 drives the CIS carriage 35 to a position different from the current position. Will be done. As a result, the contact glass 42a moves together with the CIS 40 in the transport path width direction. Since the passing position of the paper P in the transport path width direction is constant, as a result, the edge passing position of the paper P on the surface of the contact glass 42a deviates from the current position in the transport path width direction. Therefore, the light passing near the edge of the paper P on the surface of the contact glass 42a is not blocked by the paper dust. Therefore, the edge detection accuracy of the paper P by CIS40 can be sufficiently ensured. Further, according to the above configuration, since it is only necessary to move the CIS carriage 35 in the transport width direction, it is not necessary to stop the printing operation as compared with the case where the surface of the contact glass 42a is cleaned by using a cleaning member. , Printing efficiency can be improved.

Further, in the present embodiment, the control unit 200 moves the CIS carriage 35 inward from the current position in the transport width direction by a predetermined amount δ by the carriage drive mechanism 50, thereby moving the CIS carriage 35 in the transport width direction. It is configured to change the position of to a position different from the current position.

According to this configuration, the direction in which the CIS carriage 35 is moved is limited to one direction (inside the transport width direction), so that the destination of the CIS carriage 35 does not overlap with the past movement position. Therefore, the destination of the CIS carriage 35 can always be set to a position that is not affected by the paper dust accumulated on the contact glass 42a.

Further, the predetermined number of sheets is set by the user via the operation panel 72. According to this, when the user sets the predetermined number of sheets to an appropriate value, the predetermined number of sheets is too large and the position correction timing of the CIS carriage 35 is delayed, or the predetermined number of sheets is too small and the position correction of the CIS carriage 35 is not possible. You can avoid problems such as being executed as needed.

According to the present embodiment, the CIS carriage 35 is in the first position (paper size is a standard size) when the rear end surface and the front end surface of the CIS carriage 35 come into contact with the inner surfaces of the side frames 31a and 31b of the unit housing 31. It is positioned at the original position of the case) and the second position (the original position when the paper size is large). Therefore, it is possible to improve the positioning accuracy when moving the CIS carriage 35 to the original position according to the paper size.

Further, the pressing force of the CIS carriage 35 on the side frames 31a and 31b can be stabilized by utilizing the load of the torque limiter without applying a load to the CIS drive motor 51. Therefore, when the CIS carriage 35 is moved to the original position and 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 from occurring, and the original CIS carriage 35 can be used. Positional accuracy at the position is improved.

In the present embodiment, the printer 100 further includes a PI sensor 62 (original position detection sensor) that detects the original position (first position or second position) of the CIS carriage 35. Then, when the number of sheets counted by the number counting unit 201 reaches a predetermined number, the control unit 200 is configured to move the CIS carriage 35 from the current position to the original position and then to the target position by the carriage drive mechanism 50. Has been done.

According to this configuration, the movement accuracy when moving the CIS carriage 35 to the target position can be improved as much as possible.

<< Other Embodiments >>
In the above embodiment, the position of the CIS carriage 35 is different depending on whether the size of the paper P to be printed is a standard size or a large size, but the position is not limited to this, for example, CIS. The carriage 35 may simply be moved to a first position or a correction position relative to the first position. In this case, it is necessary to increase the size of the CIS 40 so that the edges of both the standard size and the large size paper P can be detected by the CIS 40.

In the above embodiment, the printer 100 is configured to be able to use different sizes of paper P, but the present invention is not limited to this, and only one size (for example, only A4 size) may be used. ..

In the above embodiment, the light source unit 41 is arranged so as to face the CIS 40 with the fourth paper transport path T6 interposed therebetween, but the present invention is not limited to this. The light source unit 41 may be provided on the same side as the CIS 40 with respect to the fourth paper transport path T6. In the example of the above embodiment, the light source unit 41 may be housed in the CIS carriage 35. In this case, the edge detection of the paper P can be performed by the CIS 40 by utilizing the fact that the amount of reflected light differs between the passing region and the non-passing region of the paper P.

In the above embodiment, the inkjet printer 100 has been described as an example of the image forming apparatus, but the printing method is not limited to the inkjet type, and may be, for example, an electrophotographic method. Further, the image forming apparatus is not limited to the printer 100, and may be, for example, a copying machine, a facsimile, a multifunction device (MFP), or the like.

As described above, the present invention is useful for an image forming apparatus, and is particularly useful when applied to a printer, a facsimile, a multifunction device (MFP), or the like.

P: Paper δ: Predetermined amount T6: Fourth paper transport path (paper transport path)
3: Image recording unit 40: CIS
42a: Contact glass 50: Carriage drive mechanism 63: PI sensor (in-situ detection sensor)
72: Operation panel 100: Printer (image forming device)
200: Control unit 201: Number of sheets counting unit

Claims (5)

An image recording unit that records an image on paper transported along a paper transport path, contact glass arranged facing the paper transport path, and contact glass provided on the opposite side of the contact glass to the paper transport path side. An image forming apparatus including an edge detection sensor that detects an edge in the width direction of paper by receiving light transmitted through the contact glass.
A carriage configured to hold the edge detection sensor and the contact glass and to move in the transport width direction orthogonal to the paper transport direction.
A carriage drive mechanism that drives the carriage in the transport width direction,
Further provided with a control unit for controlling the carriage drive mechanism,
The control unit has a number counting unit that counts the cumulative number of sheets of the same size that have passed over the contact glass in a state where the carriages are positioned at the same position in the transport width direction. When the number of sheets counted by the unit reaches a predetermined number, the carriage is driven by the carriage drive mechanism to change the position of the carriage in the transport width direction to a position different from the current position. Image forming device. In the image forming apparatus according to claim 1,
It also has an operation panel that accepts user operations.
An image forming apparatus in which the predetermined number of sheets is set by a user via the operation panel. In the image forming apparatus according to claim 1 or 2.
When the number of sheets counted by the number counting unit reaches the predetermined number, the control unit moves the carriage to a position separated by a predetermined amount inward in the transport width direction from the current position by the carriage drive mechanism. An image forming apparatus configured to change the position in the transport width direction of the above to a position different from the current position. In the image forming apparatus according to any one of claims 1 to 3.
It also has a notification unit that notifies the user of information.
When the number of sheets counted by the number-of-sheet counting unit reaches the predetermined number of sheets, the control unit sets the paper at the different position before moving the carriage to the different position by the carriage drive mechanism. If it is determined whether or not the edge in the width direction of the is a detectable position and the edge is not a detectable position, the user is urged to clean the contact glass through the notification unit. An image forming apparatus that is configured to provide notification for. In the image forming apparatus according to any one of claims 1 to 4.
Further equipped with an in-situ detection sensor that detects the in-situ of the carriage,
When the number of sheets counted by the number counting unit reaches the predetermined number, the control unit is configured to move the carriage from the current position to the original position and then to a different position by the carriage drive mechanism. An image forming device.

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