JP6740706B2 - Image forming apparatus and head position adjusting method - Google Patents

Description

The present invention relates to an image forming apparatus and a head position adjusting method.

Entities with large print demands typically use production printers. A production printer is an image forming apparatus that has been commercialized in consideration of mass printing, and is used to build a printing system (hereinafter referred to as “continuous paper printer”) that prints on a large roll-shaped print medium.

Production printers typically include a print engine and a controller that controls the overall operation of the printing system. The print engine includes one or more printhead assemblies, each assembly including a printhead (or printhead array) and a printhead controller. Each printhead includes a plurality of very small nozzles that are capable of ejecting ink droplets controlled by a printhead controller. In the print head array, a plurality of print heads having nozzles are arranged in the transport direction at a distance over the width of the print medium (width in the cross direction of the transport direction).

During printing, the print medium is conveyed under the nozzles of the print head, and ink droplets are ejected from the nozzles at regular intervals to form pixels (images) on the print medium. A steering system is usually mounted so that the print media is properly conveyed under the nozzles. This steering system is a system capable of changing the position of the print medium in the intersecting direction of the conveying direction.

However, even if the position of the print medium in the cross direction can be appropriately adjusted, for example, fluctuation in the cross direction of the print medium (meandering) may occur during printing due to a change in tension applied to the print medium. Even if the amount of meandering (the amount of displacement per unit time in the intersecting direction) is small, the print quality can be significantly reduced. For example, when using multiple printheads to form mixed color pixels, the amount of meandering at each printhead may be added. For example, if the print medium moves to one side at the position of the print head on the upstream side and the print medium moves to the other side at the position of the print head on the downstream side, the position where ink droplets are ejected meanders. It will be shifted by the width (amplitude) of the quantity. For this reason, a printed job, that is, a pixel in which droplets are not ejected to an appropriate position on the printed print medium is easily visible, and print quality may be significantly deteriorated.

In order to suppress such deterioration of print quality, there is a production printer in which a print head can be moved in the cross direction by a positioning device using an actuator (see, for example, Japanese Patent Laid-Open No. 2004-242242). In this production printer, the sensor detects the meandering amount of the print medium, that is, the edge position in the intersecting direction of the print medium, and drives the positioning device to move the print head.

In order to move the print head to the correct position, it is necessary to accurately detect the edge position in the width direction of the print medium, that is, the edge position in the horizontal direction that intersects the intersecting direction of the transport direction. However, the output signal of the sensor that detects the edge position does not always match the ideal output signal. Therefore, there is usually an error between the meandering amount recognized from the output signal of the sensor and the actual meandering amount. Therefore, conventionally, the relationship between the output signal of the sensor and the actual meandering amount is measured, and the meandering amount can be accurately specified from the output signal of the sensor by using the measurement result of the relationship.

Mounting such a sensor on a production printer does not always mount the sensor in an ideal position. A mounting error, which is the distance between the ideal position and the actually mounted position, may occur. When the mounting error is present, the print head cannot be moved to an appropriate position, so that the print quality is degraded. For this reason, the conventional program reduction printer has a problem that it cannot always properly cope with meandering of the print medium.

The present invention has been made to solve such problems, and an object thereof is to more appropriately deal with meandering of a print medium.

In order to solve the above problems, one embodiment of the present invention is an image forming apparatus which forms an image on a print medium by using a plurality of heads for ejecting droplets, and A plurality of detection units that are provided to detect the position of the edge of the print medium that intersects the intersecting direction of the conveyance direction of the print medium, and the target head that is a head to be moved among the plurality of heads intersect the intersection. In the direction, one or more drive units to be moved, and a specifying unit that specifies, for each of the heads, a positional relationship in the cross direction between the head and the corresponding detection unit among the plurality of detection units, Based on the positional relationship specified by the specifying unit, a correcting unit for correcting the position of the edge detected by each of the plurality of detecting units, and each of the plurality of detecting units corrected by the correcting unit are detected. A movement control unit that moves the target head using the driving unit based on the position of the edge, and the specifying unit moves the head by the driving unit for each head, The positional relationship is specified by causing the corresponding detection unit to detect the edge of the member whose position in the intersecting direction changes according to the position .

According to the present invention, it is possible to more appropriately deal with the meandering of the print medium.

FIG. 1 is an external view showing an example of a continuous paper printing system to which the image forming apparatus according to the present embodiment is applied. FIG. 6 is a diagram illustrating an arrangement of print heads included in a production printer to which the present embodiment is applied, and an adverse effect caused by meandering of printing paper. FIG. 6 is a diagram illustrating a moving mechanism of a print head. It is a figure explaining an example of functional composition of a controller. FIG. 3 is a diagram illustrating an example of a print head and its peripheral structure. It is a figure explaining the state after moving a plate from the state shown in FIG. It is a figure explaining the example of the moving method of a plate (reference position on movement). It is a figure explaining the example of the moving method of a plate (final position on movement). It is a figure explaining the content of a correspondence table and a correction amount table. It is a figure explaining the example of the method of cleaning the light-receiving surface of a light-receiving part using a plate (state before a cleaning start). It is a figure explaining the example of the method of cleaning the light-receiving surface of a light-receiving part using a plate (state during cleaning).

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an external view showing an example of a continuous paper printing system to which the image forming apparatus according to the present embodiment is applied.

The continuous paper printing system 1 can use, for example, a wound printing paper 5 as a printing medium. The image forming apparatus according to the present embodiment is realized as a production printer 2 to which the printing paper 5 is supplied and which forms an image on the supplied printing paper 5. The continuous paper printing system 1 includes the production printer 2 and one or more rollers 3. The roller 3 shown in FIG. 1 is used for conveying the printing paper 5 in a portion discharged from the production printer 2, applying tension to the printing paper 5, and the like.

The production printer 2 to which the present embodiment is applied is capable of forming a full-color image using inks of cyan (C), magenta (M), yellow (Y), and black (K), for example. is there. Therefore, the production printer 2 is provided with four print heads, and each print head ejects a droplet of ink of a corresponding color toward the printing paper 5.

FIG. 2 is a diagram for explaining an arrangement of print heads included in a production printer to which the present embodiment is applied and an adverse effect caused by meandering of printing paper.

As shown in FIG. 2, in the production printer 2, four print heads 201 (201K, 201C, 201M, 201Y) are arranged in a line in the carrying direction for carrying the print paper 5. The width in the longitudinal direction of each print head 201, that is, the width in the cross direction of the transport direction is basically the same, and the basic position in the cross direction of the transport direction (hereinafter referred to as “reference position”) is also the same. , As shown by the reference line 211. As a result, the print heads 201 are arranged so that ink droplets can be projected onto the printing paper 5 within the same width in the crossing direction of the transport direction. Hereinafter, the intersecting direction of the conveyance direction of the printing paper 5 is also referred to as “width direction”.

K, C, M, and Y attached to the reference numeral 201 indicate black, cyan, magenta, and yellow, respectively. Thus, in each print head 201, the print head 201K is a head that ejects black ink droplets. Similarly, the print head 201C is a head for ejecting cyan ink droplets, the print head 201M is for ejecting magenta ink droplets, and the print head 201Y is for ejecting yellow ink droplets.

The four solid lines 202 (202K, 202C, 202M, 202Y) shown in FIG. 2 are the actual ink droplets on the printing paper 5 when the ink droplets are ejected by the respective print heads 201 on the reference line 212. It shows the change in the position where is attached due to meandering.

As shown in FIG. 2, when the printing paper 5 meanders, that is, the position of the edge on the side intersecting the width direction of the printing paper 5 changes in the width direction, the position in the transport direction, or the time. In this case, the positional relationship in the width direction between each print head 201 and the printing paper 5 is not constant. Therefore, even if the ink droplets are made to project from the respective print heads 201 at positions on the reference line 212, the positions in the width direction of the printing paper 5 to which the respective ink droplets actually adhere also differ depending on the positional relationship. The print quality deteriorates as the range of positions where the ink droplets adhere increases, that is, the range in the width direction of the four solid lines 202 increases. For this reason, the production printer 2 can move the print head 201 in the width direction.

FIG. 3 is a diagram illustrating a moving mechanism of the print head. Here, for the sake of convenience, the print head 201 shows only two print heads 201K and 201C.

The print head 201K is the first to form an image on the printing paper 5. From this, in the present embodiment, the print head 201K is excluded from the movement targets, and the other three print heads 201 are set as the movement targets. Thereby, the positions of the three print heads 201 in the width direction are adjusted so as to match the positional relationship of the print head 201K and the printing paper 5 in the width direction. Δ in FIG. 3 indicates the distance by which the print head 201C is moved in the arrow direction by the adjustment. Hereinafter, unless otherwise specified, the “positional relationship” is used to mean a positional relationship in the width direction. Similarly, the movement of the print head 201 is used to indicate the movement in the width direction thereof.

In order to specify the positional relationship between each print head 201 and the printing paper 5, an edge sensor 301 (301K, 301K, which detects the position of the edge on the side intersecting the width direction intersecting direction of the printing paper 5 for each print head 201). 301C etc.) is installed. Each edge sensor 301 corresponds to a detection unit in a narrow sense in this embodiment.

Each print head 201 is movably supported in its position, and its position is movable by the power transmitted from the linear actuator 303 via the bracket 302. Each linear actuator 303 is driven by the controller 304. For this reason, the moving mechanism has a configuration including each edge sensor 301, each bracket 302, each linear actuator 303, and the controller 304.

All signals output by each edge sensor 301 are input to the controller 304. As a result, the controller 304 specifies the edge position of the printing paper 5 for each edge sensor 301, and uses the specification result to determine the direction in which the corresponding print head 201 should be moved and the moving distance thereof. Each linear actuator 303 is driven according to the determination.

In this way, the controller 304 is an information processing device (computer) that adjusts the position of each print head 201. As shown in FIG. 3, the controller 304 includes an A/D (Analog to Digital) converter group 4041, an I/F (InterFace) controller 3042, a drive circuit group 3043, a CPU (Central Processing Unit) 3044, and a PROM (Programmable Read). An only memory (3045) and a RAM (random access memory) 3046 are provided.

The A/D converter group 4041 is a circuit group for converting an analog signal output by each edge sensor 301 into a digital signal. The I/F controller 3042 is a communication circuit that enables communication with another controller (information processing device) or the like.

The drive circuit group 3043 is a circuit group for driving an actuator including each linear actuator 303. The CPU 3044 processes the digital signal output from the A/D converter group 4041 and individually controls the drive circuits forming the drive circuit group 3043.

The PROM 3045 stores various programs executed by the CPU 3044 and various data. As a result, the CPU 3044 reads out the program to be executed from the PROM 3045 to the RAM 3046 and executes the program, thereby individually controlling the drive circuits included in the drive circuit group 3043 and performing communication via the I/F controller 3042.

FIG. 4 is a diagram illustrating a functional configuration example of the controller. The functional configuration example shown in FIG. 4 is realized by the entire controller 304 when the CPU 3044 executes a program stored in the PROM 3045.

As shown in FIG. 4, the controller 304 has, as a functional configuration, an input unit 401, a position specifying unit 402, a drive control unit 403, a drive circuit group 404, a storage unit 405, an input/output unit 406, a correction control unit 407, and a correction. An amount calculation unit 408 is included.

The input unit 401 converts an analog signal output by each edge sensor 301 into a digital signal and inputs the digital signal. The input unit 401 corresponds to the A/D converter group 4041. The drive circuit group 404 also corresponds to the drive circuit group 3043.

The position specifying unit 402 has a function of specifying the edge position of the printing paper 5 from a signal input from the input unit 401 for each edge sensor 301.

The drive control unit 403 uses the edge position of the print sheet 5 specified for each edge sensor 301 and the current position of the print head 201 corresponding to the edge sensor 301 to determine the print head 201 corresponding to the edge sensor 301. Move to a suitable position. The drive control unit 403 determines a movement direction in which the print head 201 should be moved and a movement distance in which the print head 201 should be moved, based on the edge position of the printing paper 5 and the current position of the print head 201. Thereby, the drive circuit for driving the linear actuator 303 for positioning the print head 201 is controlled according to the determination result.

The drive control unit 403 corresponds to the movement control unit in this embodiment. The movement, that is, the position adjustment, of the print head 201 is realized by a corresponding linear actuator 303, a drive circuit that drives the linear actuator 303, and a mechanism that enables the movement of the print head 201 using the linear actuator 303. From this, the drive unit according to the present embodiment includes each linear actuator 303, the drive circuit group 404, the mechanism thereof, and the like.

The edge position of the printing paper 5 is specified by, for example, information indicating the correspondence between the value of the signal output by the edge sensor 301 and the edge position of the printing paper 5 (hereinafter referred to as a “correspondence table” for convenience, see FIG. 9). 4051. The storage unit 405 is used to store the correspondence table 4051. The storage unit 405 actually corresponds to the PROM 3045 and the RAM 3046.

The input/output unit 406 has a function of inputting/outputting data to/from another controller or the like, and corresponds to the I/F controller 3042.

The edge sensor 301 for each print head 201 is installed by being attached to the production printer 2. The print head 201 is movably mounted. Therefore, both the print head 201 and the edge sensor 301 may have an error in installation.

Due to the possibility of the error, the positional relationship between the print head 201 and the edge sensor 301 is not always appropriate. The position control of the print head 201 using the detection result of the edge position of the printing paper 5 by the edge sensor 301 is the position adjustment of the print head 201 based on the detected edge position. Therefore, when the positional relationship between the print head 201 and the edge sensor 301 is not appropriate, that is, when the positional relationship has an error, the position adjustment of the print head 201 cannot be performed properly. This is because the error is also reflected in the position adjustment.

Errors that occur in the position adjustment of the print head 201 reduce print quality. Therefore, in order to suppress the deterioration of print quality, it is necessary to deal with the error. In this embodiment, the positional relationship between the print head 201 and the edge sensor 301 is confirmed, and the correction amount for the correspondence table 4051 is calculated according to the confirmation result.

This correction amount is calculated according to the correspondence table 4051 and is stored separately from the correspondence table 4051. Therefore, hereinafter, the information 4052 including the calculated correction amount group will be referred to as a “correction amount table”. The correction amount table 4052 is stored in the storage unit 405.

The correction amount table 4052 is generated, that is, the positional relationship between each print head 201 and the edge sensor 301 corresponding to the print head 201 is specified by, for example, an instruction from another controller. The instruction is input by the input/output unit 406 and output to the correction control unit 407. The correction control unit 407 performs control for generating the correction amount table 4052 by inputting the instruction.

This instruction is input, for example, when the production printer 2 is initialized or when a predetermined operation is performed by the user. Alternatively, it is input when a predetermined condition is satisfied. The situation in which this instruction is input is not particularly limited.

FIG. 5 is a diagram illustrating an example of the print head and its peripheral structure. 5A is a front view (an external view from the viewpoint from below in FIG. 3), and FIG. 5B is a side view (an external view from the viewpoint from the right side in FIG. 3). Before describing the details of the control executed by the correction control unit 407, each print head 201 and its peripheral structure will be specifically described with reference to FIGS. 5 and 6.

As shown in FIG. 5A, in the print head 201, strip-shaped convex portions 201 a provided on both side surfaces of the print head 201 are inserted into concave portions 503 a provided on the slide rail 503. The two slide rails 503 are attached to a frame 501 (501a, 501b) arranged so as to sandwich the print head 201. As a result, the print head 201 is movably supported in the width direction.

As shown in FIGS. 5A and 5B, a bracket 302 is attached to the side surface of the print head 201 on the frame 501a side. The linear actuator 303 to which one end of the bracket 302 is connected is supported by the bracket 502 attached to the frame 501a.

The linear actuator 303 is an actuator of the type that transmits power via the rod 303a, and the amount of protrusion of the rod 303a can be finely adjusted. As a result, the print head 201 moves in position according to the protrusion amount of the rod 303a. For this reason, each linear actuator 303 is also used for positioning to maintain the position of the corresponding print head 201 in a fixed manner.

As shown in FIGS. 5A and 5B, an arm 504 is attached to the side surface of the print head 201 on the frame 501a side. An end portion 504a of the arm 504 is pivotally supported by the print head 201, and a plate 505 is attached to the other end portion.

In the present embodiment, as the edge sensor 301, an optical sensor including a light emitting section 301a and a light receiving section 301b is adopted. The edge sensor 301 is attached at a position where the edge position of the printing paper 5 can be detected.

Inside the print head 201, an actuator (for example, a solenoid) for rotating the end portion 504a of the arm 504 forward and backward about an axis is provided. As a result, the plate 505 attached to the end of the arm 504 moves from the state shown in FIGS. 5(a) and 5(b) to the state shown in FIGS. 6(a) and 6(b), and vice versa. Can be moved. 6A and 6B are views for explaining a state in which the plate is moved. FIG. 6A shows a front view and FIG. 6B shows a side view.

The plate 505 is a member that is supposed to be used as a substitute for the printing paper 5. Therefore, the material, thickness, etc. of the plate 505 are based on the assumption of the printing paper 5. The state shown in FIGS. 6A and 6B is a case where the printing sheet 5 is used as a substitute, and the edge sensor 301 can detect the state. From this, the states shown in FIGS. 6A and 6B are hereinafter referred to as “detectable state”. On the other hand, the state shown in FIGS. 5A and 5B will be referred to as “evacuation state” hereinafter.

The reason why the plate 505 can be automatically moved in this manner is to enable the correction amount table 4052 to be generated (including updating here) reliably and quickly when non-printing. When the plate 505 is manually installed or moved to the state shown in FIGS. 6A and 6B, that is, the detectable state, a troublesome work must be performed, and if the work is not performed, the correction amount The table 4052 cannot be generated. For this reason, automatically moving the plate 505 is useful in terms of user convenience and reduction in productivity.

Even if the above problems occur, the manufacturing cost can be further suppressed when the plate 505 is not automatically moved. Therefore, if it is not necessary to further reduce the manufacturing cost or to generate the correction amount table 4052 quickly, the plate 505 may be manually switched to the detectable state or moved.

The correction control unit 407 uses this plate 505 to perform control for generating the correction amount table 4052. A drive circuit for driving the actuator for moving the position of the plate 505 (hereinafter, referred to as “second drive circuit” to distinguish from the drive circuit for the linear actuator 303) is included in the drive circuit group 404. .. From this, when generating the correction amount table 4052, the correction control unit 407 first causes each second drive circuit to drive the actuator via the drive control unit 403, and the plate 505 can be detected from the retracted state. Move to.

The plate 505 in the detectable state can be detected by the edge sensor 301. The detection result, for example, the value of the output signal of the edge sensor 301 is output from the correction amount calculation unit 408 to the correction control unit 407.

The correction control unit 407 drives via the drive control unit 403 and the drive circuit while checking the value of the signal output from the correction amount calculation unit 408 for each linear actuator 303, and drives the position of the print head 201, that is, The position of the plate 505 is moved.

7 and 8 are diagrams illustrating an example of a plate moving method. FIG. 7 shows the reference position for the movement of the plate 505, and FIG. 8 shows the final position for the movement of the plate 505. 7A and 8A are top views (views from above in FIGS. 5 and 6), FIG. 7B, and FIG. 8B are side views ( 5(b) and FIG. 6(b) are the same viewpoints). 7 and 8, reference numeral 701 denotes a light receiving surface included in the light receiving unit 301b. Further, hereinafter, the right side and the left side are described assuming the viewpoints of FIGS. 7 and 8 (and FIGS. 5 and 6).

The correction control unit 407 uses the linear actuator 303 to move the print head 201 to the right, and confirms the position where the value of the signal output by the edge sensor 301 does not change at a high level. As shown in FIGS. 7A and 7B, this position is a position for receiving the light emitted from the light emitting unit 301a on the entire light receiving surface 701, and this position becomes the reference position for movement. ..

The correction control unit 407 moves the print head 201 (plate 505) to the reference position, and then uses the linear actuator 303 to move the print head 201 toward the left stepwise in small steps. The correction control unit 407 notifies the correction amount calculation unit 408 of the movement distance from the reference position each time the print head 201 is moved, and the correction amount calculation unit 408 notifies the correction amount calculation unit 408 of the movement distance and the edge sensor at the movement distance. The value of the output signal 301 and the value are saved.

The movement of the print head 201 is continued until the output signal value of the edge sensor 301 does not change at a low level, that is, as shown in FIGS. 8A and 8B, the entire light receiving surface 701 is a light emitting unit. The process is repeated until the light emitted from 301a cannot be received. The position where the entire light receiving surface 701 cannot receive light is the final position on the movement.

FIG. 9 is a diagram for explaining the contents of the correspondence table and the correction amount table. In FIG. 9, the broken line shows the contents of the correspondence table, and the solid line shows the change of the value of the signal output by the edge sensor 301 with respect to the position of the plate 505 (denoted as “actual sensor output” in FIG. 9 ).

In FIG. 9, the position where the signal value of the edge sensor 301 is 0 is 0 of the edge position. This is because the final position is the reference position at the edge position of the printing paper 5. The reference position may be the reference position at the edge position of the printing paper 5, or may be another position, for example, the center of the range in which the edge position can be detected.

The correction control unit 407. After moving the print head 201 to the final position, the correction amount calculation unit 408 is instructed to calculate the difference δ between the correspondence table 4051 and the actually confirmed signal value of the edge sensor 301.

As shown in FIG. 9, this difference δ is the difference between the signal value indicated by the correspondence table 4051 at the same position and the actual signal value. This difference δ is the correction amount, and the correction amount table 4052 stores the difference δ for each position as the correction amount. Accordingly, when the correction amount table 4052 exists, the position specifying unit 402 further refers to the correction amount table 4052 to specify the edge position of the printing paper 5. In the following, δ will also be used as a symbol representing the correction amount.

The position specifying unit 402 can specify the edge position using the correspondence table 4051 as described above. From this, the position specifying unit 402, the input unit 401, the storage unit 405, and each edge sensor 301 correspond to a plurality of detecting units in a broad sense in the present embodiment. Since the position specifying unit 402 also specifies the edge position reflecting the correction amount table 4052, it corresponds to a part of the correcting unit in this embodiment.

The print head 201 to which the arm 504 is attached can be manufactured with high precision. The manufacture of the arm 504 and the plate 505 and the attachment of the plate 505 to the arm 504 can be performed with high precision. Therefore, the determination of the final position (or the reference position) is performed by an operation of matching the rising edge on the horizontal axis of the correspondence table 4051 with the rising edge of the actual sensor output on the horizontal axis in FIG. Equivalent to. By matching the rising edges, the position movement (position adjustment) of each print head 201 based on the edge position of the printing paper 5 can be performed with high accuracy. As a result, it is possible to appropriately cope with the variation in the position in the width direction of the printing paper 5 including the meandering, so that the deterioration of the print quality due to the meandering can be avoided or further suppressed.

The operation on the horizontal axis for matching the two rising edges can also be performed by measuring the actual distance between the edge sensor 301 and the print head 201. This is because the rising on the horizontal axis of the correspondence table 4051 is the actual distance and the distance between the position of the print head 201 that measured the distance and the reference position at the edge position of the printing paper 5 (see FIG. 6B). ), and the position is added. Since the latter can be regarded as constant, the operation on the horizontal axis can be performed by measuring the actual distance.

In the present embodiment, in addition to the operation on the horizontal axis for matching the two rising edges, the calculation of the correction amount δ for the operation on the vertical axis is also performed, and the correction amount table 4052 is generated. When such a correction amount table 4052 is generated, the position adjustment of the print head 201 can be performed with high accuracy without previously measuring the relationship between the sensor output signal and the actual meandering amount. Further, it is possible to deal with a change in the characteristics of the edge sensor 301 due to the environment or the like. Because of this, in addition to the advantages in manufacturing the production printer 2, there is an advantage in improving print quality.

The above-mentioned positional relationship is specified by using the arm 504 to which the plate 505 is attached and the edge sensor 301. On the controller 304 side, the input unit 401, the correction amount calculation unit 408, the correction control unit 407, the drive control unit 403, and the drive circuit group 404 function. From this, all of them are included in the specifying unit in the present embodiment. Since the correction amount table 4052 is generated together with the specification of this positional relationship, all of these and the position specifying unit 402 are included in the correction unit in the present embodiment.

The position identification unit 402, the drive control unit 403, the correction control unit 407, and the correction amount calculation unit 408 are realized by the CPU 3044 by reading the program stored in the PROM 3045 into the RAM 3046 and executing the program.

The present embodiment is applied to the production printer 2, but the application is not limited to the production printer 2. The present embodiment can be widely applied to an image forming apparatus that includes a plurality of heads that eject droplets, and in which the print medium (for example, the print paper 5) that is the target of image formation may meander.

In this embodiment, after the plate 505 is moved to the detectable state, the plate 505 is moved and the positional relationship between the plate 505 and the edge sensor 301 is changed. By utilizing this, the light receiving surface 701 of the light receiving portion 301b of the edge sensor 301 may be cleaned.

10 and 11 are diagrams illustrating an example of a method of cleaning the light receiving surface of the light receiving unit using the plate. 10(a) and 11(a) show a front view, and FIGS. 10(b) and 11(b) show a side view, respectively.

In this modification, as shown in FIGS. 10 and 11, the cleaning member 1001 is attached to the light receiving portion 301b side of the plate 505. Thereby, for example, the plate 505 is moved leftward from the reference position. The states shown in FIGS. 10 and 11 are states in the middle of the process. More specifically, FIG. 10 shows a state before starting cleaning, and FIG. 11 shows a state during cleaning.

In this modification, the plate 505 is moved to the left side in order to clean the entire light receiving surface 701 by the cleaning member 1001. By performing such cleaning, it is possible to prevent the signal output from the edge sensor 301 from changing due to stains on the light receiving surface 701, which is useful in maintaining print quality.

Further, in the present embodiment, when the correction amount table 4052 exists, the position specifying unit 402 also refers to the correction amount table 4052 to specify the edge position of the printing paper 5. Need not be referenced. For example, the correction amount table 4052 may be used to generate another correspondence table in which the contents of the correspondence table 4051 are changed, and the position specifying unit 402 may refer to the other correspondence table. This is also the case when only the operation on the horizontal axis is performed. For this reason, the specification of the edge position and the correction of the specification result do not have to be performed separately.

1 Continuous Paper Printing System 2 Production Printer 3 Roller 5 Printing Paper 201, 201K to 201Y Print Head 301, 301K, 301C Edge Sensor 301a Light Emitting Section 301b Light Receiving Section 302, 502 Bracket 303 Linear Actuator 303a Rod 304 Controller 401 Input Section 402 Position Specific unit 403 Drive control unit 404 Drive circuit group 405 Storage unit 406 Input/output unit 407 Correction control unit 408 Correction amount calculation unit 501, 501a, 501b Frame 503 Slide rail 504 Arm 505 Plate 701 Light receiving surface 1001 Cleaning member 3041 A/D converter Group 3042 I/F controller 3043 Drive circuit group 3044 CPU
3045 PROM
3046 RAM
4051 Correspondence table 4052 Correction amount table

JP-A-2015-13476

Claims (6)

An image forming apparatus for forming an image on a print medium using a plurality of heads for ejecting droplets,
A plurality of detection units that are provided for each of the plurality of heads and that detect the position of the edge of the print medium that intersects the intersecting direction of the print medium conveying direction
One or more drive units that move a target head, which is a head to be moved among the plurality of heads, in the cross direction,
An identifying unit that identifies, for each of the heads, a positional relationship in the intersecting direction between the head and a corresponding detector among the plurality of detectors,
Based on the positional relationship specified by the specifying unit, a correction unit for correcting the position of the edge detected by each of the plurality of detection units,
A movement control unit that moves the target head using the driving unit, based on the positions of the edges that are respectively detected by the plurality of detection units that are corrected by the correction unit;
Equipped with
The specifying unit moves the head by the driving unit for each of the heads, and causes the corresponding detecting unit to detect the edge of the member whose position in the intersecting direction changes according to the position of the head. Specify the positional relationship,
An image forming apparatus characterized by the above. Said member is an image forming apparatus according to claim 1, wherein the cleaning member for cleaning the detector is mounted, it is characterized. The member has a first position that is not in contact with the print medium conveyed, the corresponding second position capable of detection by the detection unit is switchable in claim 1 or, characterized in that 2. The image forming apparatus according to item 2 . The image forming apparatus according to claim 3 , wherein the specifying unit switches the member between the first position and the second position. The correction unit moves the head for each head by the drive unit in a state where the member is in the second position, and determines the relationship between the signal output from the detection unit and the position of the head. The image forming apparatus according to claim 3 , wherein the image forming apparatus is also corrected. A head position adjusting method used for adjusting the positions of a plurality of heads for image formation on a print medium by an information processing device,
In the information processing device,
For each head that constitutes the plurality of heads, the positional relationship in the intersecting direction between the head and a detection unit that detects an edge of the print medium intersecting the intersecting direction of the transport direction of the print medium is specified,
By reflecting the specified positional relationship, the position of the edge detected by the detection unit is specified,
Based on the identified position of the edge, the target head is moved by using a drive unit that moves the target head in the intersecting direction for each target head that is a head to be moved among the plurality of heads. In some cases
When the positional relationship is specified, the head is moved by the driving unit for each head, and the corresponding detecting unit detects the edge of the member whose position in the cross direction changes according to the position of the head. By specifying the positional relationship,
A head position adjusting method characterized by the above.