JP7354698B2 - Liquid discharge device, liquid discharge method, and program - Google Patents

Description

The present invention relates to a liquid ejection device, a liquid ejection method, and a program.

An inkjet liquid ejection device ejects ink (liquid) from the nozzles of the print head while reciprocating a carriage carrying a print head in the main scanning direction, and uses a transport roller to transport the print medium in the sub-scan direction. This process is repeated to form an image. Even when attempting to deposit ink at the same position on the recording medium, a shift may occur when the recording head moves forward and backward. Such positional deviation is called ink landing position deviation.

Misalignment of the ink landing position may occur not only due to a difference in the direction of movement during reciprocating movement, but also due to, for example, an error in attaching the recording head to the carriage.

Therefore, it has been proposed to form a test pattern on a recording medium and image the test pattern using an imaging means provided on a carriage or the like to detect the displacement of the ink landing position (for example, see Patent Document 1).

In the apparatus described in Patent Document 1, a first marker is formed on a recording medium, and after the recording medium is conveyed by a predetermined amount, a pair of second markers are formed using a nozzle different from the nozzle that formed the first marker. Then, by detecting the positions of the first marker and the pair of second markers in the captured image, the displacement of the ink landing position is detected.

However, in Patent Document 1, the test pattern includes a first marker and a pair of second markers, but each marker has the same shape and density, and is either the first marker or the second marker. cannot be clearly identified. For this reason, the apparatus described in Patent Document 1 may not be able to detect the amount of deviation in image formation with high precision.

The disclosed technology has been developed to solve this problem in view of the above-mentioned circumstances, and aims to detect the amount of deviation in image formation with high precision.

The disclosed technology forms at least three first markers by moving a recording head that discharges liquid in a first direction relative to a recording medium, and forms at least two of the three first marker formation positions. A pair of measurements in which a second marker is formed at two formation positions, a reference marker consisting only of the first marker, and the first marker and the second marker are layered and formed so as to sandwich the reference marker. a pattern forming means for forming a pattern including a marker; a reading means for reading the pattern; and an interval measuring means for measuring the distance between the reference marker and the measurement marker in the first direction from information read by the reading means. This is a liquid ejection device having the following.

The amount of deviation in image formation can be detected with high precision.

FIG. 1 is a perspective view showing a schematic configuration of a liquid ejection device according to a first embodiment. FIG. 3 is a top view showing the internal configuration of the liquid ejection device. FIG. 3 is a diagram showing the configuration of an imaging section mounted on a carriage. FIG. 2 is a block diagram showing an example of the hardware configuration of a liquid ejection device. FIG. 2 is a functional block diagram showing a configuration example of an image processing section. FIG. 2 is a block diagram showing a configuration example of a printhead control section, a drive waveform generation circuit, and a printhead driver. FIG. 2 is a block diagram showing a functional configuration related to detection of landing position deviation. It is a figure explaining the formation operation of a 1st marker. It is a figure explaining the formation operation of the 2nd marker. FIG. 6 is a diagram showing a state in which a first marker is formed when the recording head is tilted. FIG. 7 is a diagram showing a state in which a second marker is formed when the recording head is tilted. 3 is a flowchart illustrating test pattern formation and positional deviation detection operations. FIG. 7 is a block diagram showing a modified example of a functional configuration related to detection of landing position deviation. FIG. 3 is a diagram illustrating timing adjustment of a common drive waveform signal. FIG. 7 is a block diagram showing a functional configuration related to detection of landing position deviation according to a second embodiment. It is a figure explaining the formation operation of a 1st marker. It is a figure explaining the formation operation of the 2nd marker. 3 is a flowchart illustrating test pattern formation and positional deviation detection operations. FIG. 3 is a diagram showing an example of a test pattern and a reference frame. 7 is a flowchart showing determination processing based on a reference frame. It is an example of a figure explaining operation of a carriage in more detail. 1 is an example of a diagram schematically showing a configuration for a print position deviation sensor to detect edges of a test pattern; FIG.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In each drawing, the same components are given the same reference numerals, and redundant explanations may be omitted. In the embodiments described below, an inkjet printer that forms an image by ejecting ink (liquid) onto a recording medium will be exemplified as an example of a liquid ejection apparatus to which the present invention is applied.

[First embodiment]
A liquid ejecting device according to a first embodiment of the present invention will be described below.

<Schematic configuration of liquid ejection device>
FIG. 1 is a perspective view showing a schematic configuration of a liquid ejection device 1 according to the first embodiment. Note that FIG. 1 shows the inside of the liquid ejection device 1 in a transparent manner. FIG. 2 is a top view showing the internal configuration of the liquid ejection device.

As shown in FIG. 1, each component constituting the liquid ejection device 1 is arranged inside an exterior body 2. As shown in FIG. A cover member 2a is provided on the exterior body 2 so as to be openable and closable.

The liquid ejecting device 1 includes a carriage 5 that reciprocates in a main scanning direction (arrow A direction) as a first direction. The carriage 5 is supported by a main guide rod 3 extending along the main scanning direction. Further, the carriage 5 is provided with a connecting piece 5a. The connecting piece 5a has a function of engaging with the sub-guide member 4 provided parallel to the main guide rod 3 and stabilizing the posture of the carriage 5.

The carriage 5 is connected to a timing belt 11 stretched between a driving pulley 9 and a driven pulley 10. The drive pulley 9 is rotated by the main scanning motor 8 . The driven pulley 10 has a mechanism that applies a predetermined tension to the timing belt 11 and adjusts the distance between it and the drive pulley 9.

The carriage 5 reciprocates in the main scanning direction by driving the timing belt 11 by the main scanning motor 8 . The amount and speed of movement of the carriage 5 are controlled based on, for example, an encoder value output by an encoder sensor 13 provided on the carriage 5 that detects a mark on an encoder sheet 14 (see FIG. 2).

As shown in FIG. 2, recording heads 6y, 6m, 6c, and 6k are mounted on the carriage 5. The recording head 6y discharges yellow (Y) ink. The recording head 6m discharges magenta (M) ink. The recording head 6c discharges cyan (C) ink. The recording head 6k discharges black (B) ink. Hereinafter, these recording heads 6y, 6m, 6c, and 6k will be collectively referred to as the recording head 6.

The recording head 6 is formed with a nozzle surface (ejection surface) in which a plurality of nozzles 6a (see FIG. 8) are arranged in the sub-scanning direction. The recording head 6 is supported by the carriage 5 so that the nozzle surface faces a recording paper P as a recording medium.

Further, the liquid ejection device 1 is provided with a cartridge 7 (see FIG. 1). The cartridge 7 is an ink supply body for supplying ink to the recording head 6. The cartridge 7 is not mounted on the carriage 5, but is placed at a predetermined position within the liquid ejection device 1. The cartridge 7 and the recording head 6 are connected by a pipe for supplying ink from the cartridge 7 to the recording head 6.

A platen 16 is provided at a position facing the ejection surface of the recording head 6. The platen 16 is for supporting the recording paper P when ink is ejected from the recording head 6 onto the recording paper P. The platen 16 is provided with a large number of through holes penetrating in the thickness direction, and rib-shaped protrusions are formed to surround each through hole. A suction fan is provided on the opposite side of the platen 16 from the surface that supports the recording paper P. This suction fan makes it possible to prevent the recording paper P from falling off the platen 16. The recording paper P is held between conveyance rollers driven by a sub-scanning motor 141 (see FIG. 4), which will be described later, and is intermittently conveyed over the platen 16 in the sub-scanning direction (direction of arrow B) as a second direction. Ru. The second direction is orthogonal to the first direction.

The liquid ejecting device 1 intermittently transports the recording paper P in the sub-scanning direction, and reciprocates the carriage 5 in the main scanning direction while the transport of the recording paper P is stopped. During this reciprocating movement, the nozzles 6a of the recording head 6 are selectively driven according to image data to eject ink onto the recording paper P on the platen 16, thereby forming an image on the recording paper P.

Further, the liquid ejecting apparatus 1 includes a maintenance mechanism 15 for maintaining the reliability of the recording head 6. The maintenance mechanism 15 performs cleaning and capping of the ejection surface of the print head 6, discharges unnecessary ink from the print head 6, and the like.

<Configuration of imaging section>
FIG. 3 is a diagram showing the configuration of the imaging section 20 mounted on the carriage 5. As shown in FIG. The imaging unit 20 is mounted on the carriage 5 in order to image the test pattern TP formed on the recording paper P.

The imaging unit 20 includes a two-dimensional sensor 21 and an imaging lens 22. The two-dimensional sensor 21 is an imaging element (imaging means) such as a CCD (Charge-Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor. The imaging lens 22 forms an optical image of the test pattern TP formed on the recording paper P onto the light receiving surface of the two-dimensional sensor 21 . The imaging unit 20 converts an optical image incident from the recording paper P through the imaging lens 22 into an electrical signal using the two-dimensional sensor 21, and outputs it as a captured image of the test pattern TP.

The imaging unit 20 is attached, for example, to the side surface of the carriage 5, with the optical axis of the imaging lens 22 being perpendicular to the surface of the recording paper P set on the platen 16. Note that the imaging unit 20 only needs to be arranged so as to be able to image the test pattern TP formed on the recording paper P, and does not need to be mounted on the carriage 5.

Further, the imaging unit 20 is provided with a two-dimensional sensor CPU (Central Processing Unit) 23 (see FIG. 4) that controls the two-dimensional sensor 21 and processes the captured image captured by the two-dimensional sensor 21. .

<Example of hardware configuration of liquid ejection device>
FIG. 4 is a block diagram showing an example of the hardware configuration of the liquid ejection device 1. As shown in FIG. The liquid ejection device 1 includes a main control board 100, a head relay board 200, and an image processing board 300.

The main control board 100 includes a CPU 101, an FPGA (Field-Programmable Gate Array) 102, a RAM (Random Access Memory) 103, a ROM (Read Only Memory) 104, an NVRAM (Non-Volatile Random Access Memory) 105, a motor driver 106, A drive waveform generation circuit 107 and the like are mounted.

The CPU 101 controls the entire liquid ejection device 1 . For example, the CPU 101 uses the RAM 103 as a work area, executes various control programs stored in the ROM 104, and outputs control commands for controlling various operations in the liquid ejection device 1. At this time, the CPU 101 performs various operation controls in the liquid ejection apparatus 1 in cooperation with the FPGA 102 while communicating with the FPGA 102 .

In particular, in the liquid ejection apparatus 1, the CPU 101 has a function of forming a test pattern TP, a function of obtaining information regarding the amount of deviation in image formation based on the measured value of the interval between markers included in the test pattern TP, and outputting this information. Realize functions such as Note that details of these functions will be described later.

The CPU control unit 111 has a function of communicating with the CPU 101. The memory control unit 112 has a function of accessing the RAM 103 and ROM 104. The I2C control unit 113 has a function of communicating with the NVRAM 105.

The sensor processing unit 114 processes sensor signals from various sensors 130. Various sensors 130 is a general term for sensors that detect various states in the liquid ejection device 1. In addition to the encoder sensor 13 described above, the various sensors 130 include a paper sensor that detects the passage of the recording paper P, a cover sensor that detects the opening of the cover member 2a, a temperature and humidity sensor that detects the environmental temperature and humidity, and a paper sensor that detects the passage of the recording paper P. It includes a paper fixing lever sensor that detects the operating state of the lever that fixes the paper, a remaining amount detection sensor that detects the amount of ink remaining in the cartridge 7, and the like. Note that an analog sensor signal output from a temperature/humidity sensor or the like is converted into a digital signal by an AD converter mounted on, for example, the main control board 100 and input to the FPGA 102.

The motor control unit 115 controls various motors 140. The various motors 140 are a general term for motors included in the liquid ejection device 1. The various motors 140 include a main scanning motor 8 for operating the carriage 5, a sub-scanning motor 141 for transporting the recording paper P in the sub-scanning direction, a paper feed motor for feeding the recording paper P, and a maintenance mechanism. A maintenance motor for operating 15 is included.

Here, a specific example of control by cooperation between the CPU 101 and the motor control unit 115 of the FPGA 102 will be described, taking the operation control of the main scanning motor 8 as an example. First, the CPU 101 notifies the motor control unit 115 of the moving speed and moving distance of the carriage 5 along with an instruction to start operating the main scanning motor 8 . Upon receiving this instruction, the motor control unit 115 generates a drive profile based on the movement speed and movement instruction information notified from the CPU 101, and generates a drive profile based on the encoder value (sensor signal of the encoder sensor 13) supplied from the sensor processing unit 114. A PWM command value is calculated and output to the motor driver 106 while comparing it with the value obtained by processing the PWM command value. When the motor control unit 115 completes a predetermined operation, it notifies the CPU 101 of the end of the operation.

Although an example in which the motor control unit 115 generates a drive profile has been described here, a configuration may also be adopted in which the CPU 101 generates a drive profile and instructs the motor control unit 115 to generate the drive profile. The CPU 101 also counts the number of printed sheets and the number of scans by the main scanning motor 8.

The recording head control unit 116 passes the head drive data, ejection synchronization signal LINE, and ejection timing signal CHANGE stored in the ROM 104 to the drive waveform generation circuit 107, and causes the drive waveform generation circuit 107 to generate a common drive waveform signal Vcom. The common drive waveform signal Vcom generated by the drive waveform generation circuit 107 is input to a recording head driver 210 (described later) mounted on the head relay board 200.

The two-dimensional sensor CPU 23 controls the two-dimensional sensor 21 and processes images captured by the two-dimensional sensor 21 based on operation instructions from the CPU 101 or the FPGA 102 . Specifically, the two-dimensional sensor CPU 23 sets various operating conditions for the two-dimensional sensor 21 by sending various setting signals to the imaging section 20. Further, the two-dimensional sensor CPU 23 realizes a function of measuring the interval between markers included in the test pattern TP from a captured image of the test pattern TP, a function of calculating a ratio of the intervals, and the like. Details of these functions will be described later.

<Example of hardware configuration of image processing unit>
FIG. 5 is a functional block diagram showing a configuration example of the image processing section 310 mounted on the image processing board 300.

The image processing section 310 performs gradation processing, image conversion processing, etc. on the received image data, and converts it into image data in a format that can be processed by the recording head control section 116. The image processing section 310 then outputs the converted image data to the recording head control section 116.

Specifically, the image processing section 310 includes an interface 41, a gradation processing section 42, an image conversion section 43, and an image processing section RAM44.

The interface 41 is an input unit for image data, and is a communication interface with the CPU 101 and FPGA 102. The gradation processing unit 42 performs gradation processing on the received multi-valued image data and converts it into small-valued image data. The small-value image data is image data with the number of gradations equal to the type of ink droplet (large droplet, medium droplet, small droplet) ejected by the recording head 6. Then, the gradation processing unit 42 holds the converted image data for one or more bands on the image processing unit RAM 44.

Image data for one band refers to image data corresponding to the maximum width in the sub-scanning direction that can be recorded by the recording head 6 in one scan in the main-scanning direction.

The image conversion unit 43 converts the image data for one band on the image processing unit RAM 44 in units of images output in one scan (one scan) in the main scanning direction. This conversion is performed in accordance with the configuration of the recording head 6 according to information on the printing order and the printing width (sub-scanning width of image recording per one scan) received from the CPU 101 via the interface 41.

The printing order and printing width may be one-pass printing in which an image is formed in one main scan on the recording paper P, or multiple main scans on the same area of the recording paper P using the same nozzle group or different nozzle groups. Multi-pass printing may be used in which an image is formed by scanning. Alternatively, the heads may be arranged in the main scanning direction, and different nozzles 6a may be used to strike the same area. These recording methods can be used in combination as appropriate.

The print width refers to the width in the sub-scanning direction of an image printed by one scan (one scan) of the recording head 6 in the main-scanning direction. The print width is set by the CPU 101.

The image conversion section 43 outputs the converted image data SD' to the recording head control section 116 via the interface 41.

The functions of the image processing section 310 may be executed as hardware functions such as FPGA or ASIC, or may be executed by an image processing program stored in a storage device inside the image processing section 310. Further, the function of the image processing unit 310 may be performed by software installed in a computer instead of inside the liquid ejecting device.

<Example of configuration of recording head driver, etc.>
FIG. 6 is a block diagram showing a configuration example of the printhead control section 116, the drive waveform generation circuit 107, and the printhead driver 210.

When the recording head control unit 116 receives the trigger signal Trig, which triggers the timing of ejection, it outputs the ejection synchronization signal LINE, which triggers the generation of a drive waveform, to the drive waveform generation circuit 107. Further, the recording head control unit 116 outputs an ejection timing signal CHANGE corresponding to the amount of delay from the ejection synchronization signal LINE to the drive waveform generation circuit. The drive waveform generation circuit 107 generates the common drive waveform signal Vcom at a timing based on the ejection synchronization signal LINE and the ejection timing signal CHANGE.

Furthermore, the recording head control unit 116 receives image data SD' after image processing from the above-mentioned image processing unit 310, and based on this image data SD', the recording head control unit 116 controls droplets to be ejected from each nozzle 6a of the recording head 6. A mask control signal MN for selecting a predetermined waveform of the common drive waveform signal Vcom according to the magnitude is generated. The mask control signal MN is a signal whose timing is synchronized with the ejection timing signal CHANGE. Then, the print head control unit 116 transfers the image data SD', the synchronization clock signal SCK, the latch signal LT for commanding the latch of the image data, and the generated mask control signal MN to the print head driver 210.

The recording head driver 210 includes a shift register 211, a latch circuit 212, a gradation decoder 213, a level shifter 214, and an analog switch 215.

The shift register 211 receives the image data SD' transferred from the recording head control unit 116 and the synchronization clock signal SCK. The latch circuit 212 latches each register value of the shift register 211 using a latch signal LT transferred from the print head control unit 116.

The gradation decoder 213 decodes the value latched by the latch circuit 212 (image data SD') and the mask control signal MN, and outputs the result. The level shifter 214 converts the logic level voltage signal of the gradation decoder 213 to a level at which the analog switch 215 can operate.

The analog switch 215 is a switch that is turned on/off by the output of the gradation decoder 213 provided via the level shifter 214. This analog switch 215 is provided for each nozzle 6a of the recording head 6, and is connected to an individual electrode of a piezoelectric element provided corresponding to each nozzle 6a. Further, the common drive waveform signal Vcom from the drive waveform generation circuit 107 is input to the analog switch 215 . Further, as described above, the timing of the mask control signal MN is synchronized with the timing of the common drive waveform signal Vcom.

Therefore, the analog switch 215 is turned on/off at appropriate timing according to the output of the gradation decoder 213 provided via the level shifter 214. As a result, the waveform to be applied to the piezoelectric element corresponding to each nozzle 6a is selected from among the drive waveforms forming the common drive waveform signal Vcom. As a result, the size of the droplet discharged from the nozzle 6a is controlled.

<Functional configuration related to detection of landing position deviation>
Next, a description will be given of a function related to landing position deviation detection realized by the CPU 101 of the liquid ejection device 1 and the two-dimensional sensor CPU 23.

FIG. 7 is a block diagram showing a functional configuration related to detection of landing position deviation. In this embodiment, the inclination of the print head 6 caused by an error in attaching the print head 6 to the carriage 5 can be detected based on the ink landing position.

For example, the CPU 101 uses the RAM 103 as a work area and executes the control program stored in the ROM 104 to operate the functions of the pattern forming section 400, conveyance control section 401, slope calculation section 402, information output section 403, etc. Realize.

Further, the two-dimensional sensor CPU 23 realizes functions such as the interval measuring section 404 and the ratio calculating section 405 by realizing a control program stored in the ROM, using the RAM as a work area, for example. Note that the interval measurement unit 404 and the ratio calculation unit 405 may be implemented within the CPU 101.

The conveyance control unit 401 controls the sub-scanning motor 141 for conveying the recording paper P in the sub-scanning direction via the above-mentioned motor control unit 115 and motor driver 106. For example, the conveyance control unit 401 determines the rotation speed and rotation direction of the conveyance roller based on the encoder value output from the encoder sensor 13, and sends a control command indicating the rotation speed and rotation direction to the motor control unit 115. By doing so, the conveyance of the recording paper P by the conveyance section 150 as a medium moving means is controlled. The conveyance unit 150 includes the above-described sub-scanning motor 141 and conveyance rollers.

The pattern forming section 400 reads pattern data stored in advance in the ROM 104 or the like described above, and causes the recording head 6 and the conveying section 150 to perform an image forming operation in accordance with this pattern data in cooperation with each other, thereby forming a pattern on the recording paper P. A test pattern TP is formed. The test pattern TP formed on the recording paper P is imaged by the two-dimensional sensor 21. The pattern forming unit 400 is not limited to the CPU 101, and may be a functional unit implemented in an external PC (Personal Computer) connected to the liquid ejecting apparatus 1.

The test pattern TP of this embodiment includes at least one reference marker and one measurement marker. Details of the test pattern TP will be described later.

The distance measurement unit 404 measures the distance between the reference marker and the measurement marker in the main scanning direction based on the captured image of the test pattern TP captured by the two-dimensional sensor 21. Specifically, when one of a pair of measurement markers formed with a reference marker sandwiched therebetween is set as a first measurement marker and the other is set as a second measurement marker, the difference between the reference marker and the first measurement marker is The distance b and the distance c between the reference marker and the second measurement marker are each measured. Each measurement value is, for example, a value in units of pixels of the captured image.

The ratio calculation unit 405 calculates the ratio r between the interval b and the interval c measured by the interval measurement unit 404, and sends the calculated ratio r to the slope calculation unit 402.

The inclination calculating unit 402 calculates the ideal value a of the distance between the reference marker and the measurement marker obtained from the pattern forming unit 400 and the transport distance (movement amount) Dt of the recording paper P in the sub-scanning direction when forming the test pattern TP. and the ratio r obtained from the ratio calculation unit 405, the inclination angle θ of the recording head 6 is calculated. The tilt calculation unit 402 outputs the calculated tilt angle θ to the information output unit 403.

The information output unit 403 sends information Inf representing the inclination angle θ to a panel display unit of the liquid ejection device 1, a PC externally connected to the liquid ejection device 1, and the like.

<Test pattern formation and positional deviation detection operation>
Next, the formation of the test pattern TP and the positional deviation detection operation will be described with reference to FIGS. 8 to 12. The reference marker Ks and measurement marker Km included in the test pattern TP are composed of a first marker M1 formed by a first nozzle group and a second marker M2 formed by a second nozzle group. The first marker M1 and the second marker M2 are each formed in a linear shape extending in the sub-scanning direction.

FIG. 8 is a diagram illustrating the formation operation of the first marker M1. FIG. 9 is a diagram illustrating the formation operation of the second marker M2. As shown in FIGS. 8 and 9, the recording head 6 has a plurality of nozzles 6a arranged in the sub-scanning direction. Here, the total length in the sub-scanning direction of the nozzle row constituted by the plurality of nozzles 6a is assumed to be Ln.

As mentioned above, when the recording heads 6y, 6m, 6c, and 6k of multiple colors are mounted on the carriage 5, multiple nozzle rows are arranged side by side in the main scanning direction, but this is simplified here. For simplicity, only one nozzle row is shown. The test pattern TP is formed, for example, by a nozzle array of the recording head 6k that discharges B ink. The color of the ink forming the test pattern TP is not limited to black, and may be any other color. It is preferable to use ink of a color that has the highest contrast with the color of the recording paper P.

In this embodiment, the first marker M1 is formed using the first nozzle group G1 selected from the plurality of nozzles 6a constituting one nozzle row, and the second marker M2 is formed using the second nozzle group G2. do.

The first nozzle group G1 is a nozzle row located on the rear end side in the sub-scanning direction. The second nozzle group G2 is a nozzle row located on the tip side in the sub-scanning direction. Further, in this embodiment, the number of nozzles 6a included in the first nozzle group G1 and the second nozzle group G2 is the same, and the lengths in the sub-scanning direction are both Lp. Note that the first nozzle group G1 and the second nozzle group G2 do not need to be located at each end. Further, the first nozzle group G1 and the second nozzle group G2 may include some nozzles 6a in common.

First, as shown in FIG. 8, the pattern forming unit 400 moves the recording head 6 from a predetermined starting position to the positive side of the main scanning direction (forward direction), and from the first nozzle group G1 of the recording head 6 to the recording paper. By discharging ink onto P, a first marker M1 is formed (step S10 in FIG. 12). In this embodiment, the pattern forming unit 400 forms the first markers M1 at a constant pitch in the main scanning direction. In an ideal state in which there is no deviation in the landing position of the ink, the first markers M1 are arranged with a length Lp in the sub-scanning direction, and the interval in the main-scanning direction is an ideal value a.

After forming the first marker M1, the pattern forming unit 400 moves the recording head 6 in the negative side of the main scanning direction (return direction) and returns it to the starting position without performing an ejection operation.

Next, as shown in FIG. 9, the conveyance control unit 401 conveys the recording paper P by a predetermined conveyance distance Dt in the sub-scanning direction (step S11). In the present embodiment, the conveyance distance Dt is a value obtained by subtracting the lengths Lp of the first nozzle group G1 and the second nozzle group G2 from the total length Ln of the plurality of nozzles 6a, that is, Dt=Ln−Lp.

Then, the pattern forming unit 400 moves the recording head 6 from the start position to the positive side in the main scanning direction and ejects ink from the second nozzle group G2 of the recording head 6 onto the recording paper P, thereby forming a second marker. M2 is formed (step S12). At this time, the pattern forming unit 400 forms the second markers M2 at formation positions that are partially thinned out at a predetermined thinning rate (for example, 2) from the plurality of formation positions of the first markers M1. In this embodiment, the pattern forming unit 400 forms the second markers M2 at twice the pitch of the first markers M1 so as to partially overlap the first markers M1. In an ideal state in which there is no deviation in the landing position of the ink, the second marker M2 is formed to almost completely coincide with the first marker M1.

As a result, a test pattern TP is formed on the recording paper P including a reference marker Ks consisting of only the first marker M1 and a measurement marker Km consisting of a superimposed first marker M1 and a second marker M2.

The reference marker Ks and the measurement marker Km are arranged alternately in the main scanning direction. That is, a pair of measurement markers Km are formed with the reference marker Ks in between.

This test pattern TP is imaged by the two-dimensional sensor 21, and the captured image is input to the two-dimensional sensor CPU 23 (step S13). The graph shown in FIG. 9 shows the density distribution of the captured image in the main scanning direction. The measurement marker Km has a higher density than the reference marker Ks, which is a single line, because the first marker M1 and the second marker M2 are layered.

The distance measurement unit 404 measures the distance between the reference marker Ks and the measurement marker Km based on the captured image (step S14). Based on the density of the captured image, the interval measurement unit 404 can identify a high density line as a measurement marker Km and a low density line as a reference marker Ks. Further, the interval measurement unit 404 measures the distance between peaks in the main scanning direction in the density distribution of the captured image as an interval.

Specifically, the interval measuring unit 404 selects one reference marker Ks, sets the measurement marker Km located on the negative side of the main scanning direction of the reference marker Ks as the first measurement marker, and sets the measurement marker Km located on the negative side of the reference marker Ks to the first measurement marker. Measure the distance b from the measurement marker. Further, the interval measuring unit 404 sets the measurement marker Km located on the positive side of the main scanning direction of the reference marker Ks as a second measurement marker, and measures the interval c between the reference marker Ks and the second measurement marker. The interval measurement unit 404 outputs the measured values of the intervals b and c to the ratio calculation unit 405.

Note that it is preferable that the interval measurement unit 404 changes the selected reference marker Ks, measures the intervals b and c based on each reference marker Ks, and outputs the average value of the intervals b and c as the measured value. Further, it is preferable that the interval measurement unit 404 measures the intervals b and c at a plurality of different positions in the sub-scanning direction, and averages each interval as the measured value.

8 and 9 show an ideal state in which there is no deviation in the landing position of the ink due to the inclination of the recording head 6, etc., so the intervals b and c each have the ideal value a.

FIG. 10 is a diagram showing a state in which the first marker M1 is formed when the recording head 6 is tilted. FIG. 11 is a diagram showing a state in which the second marker M2 is formed when the recording head 6 is tilted.

It is assumed that the recording head 6 is tilted in a rotating direction within a plane parallel to the surface of the recording paper P, and the tilt angle with respect to the sub-scanning direction is θ. In this case, the patterns (dot rows) of the first marker M1 and the second marker M2 have an inclination angle of θ with respect to the sub-scanning direction.

Furthermore, as shown in FIG. 11, since the first marker M1 and the second marker M2 are formed by different nozzle groups, if the recording head 6 is tilted, the first marker M1 and the second marker The formation position with M2 is shifted in the main scanning direction. Therefore, in this case, the measurement marker Km is formed by the first marker M1 and the second marker M2 that partially overlap, and the density distribution spreads in the main scanning direction.

δ shown in FIG. 11 represents the amount of deviation between the formation positions of the first marker M1 and the second marker M2 in the main scanning direction. The peak position of the density of the measurement marker Km in the main scanning direction occurs at an intermediate position between the first marker M1 and the second marker M2. Therefore, the intervals b and c are expressed by the following formulas (1) and (2), respectively.

b=a-δ/2...(1)
c=a+δ/2...(2)
Here, if the value obtained by dividing the interval b by the interval c is defined as the ratio r, that is, r = b/c, then the deviation amount δ is expressed by the following formula (3) based on the above formulas (1) and (2). be done.

δ=2a(1-r)/(1+r)...(3)
Then, using this shift amount δ, the inclination angle θ is expressed by the following formula (4).

θ=tan ^-1 (δ/Dt)...(4)
The ratio calculation unit 405 calculates the ratio r based on the measured values of the intervals b and c measured by the interval measurement unit 404 (step S15).

The slope calculation unit 402 uses the ratio r calculated by the ratio calculation unit 405, the ideal value a of the interval obtained from the pattern forming unit 400, and the transport distance Dt obtained from the transport control unit 401, and calculates the above formula ( The inclination angle θ is calculated based on 3) and (4) (step S16).

The information output unit 403 outputs the value of the inclination angle θ, a chart representing the inclination angle θ, etc. as information Inf regarding the inclination angle θ to the panel display unit or the display unit of the external PC for display (step S17). Further, the information output unit 403 may cause the display unit or the like to display an error display when the tilt angle θ exceeds a threshold value.

By referring to the information Inf representing the inclination angle θ shown on the display unit or the like, the user can adjust the mounting position of the recording head 6 with respect to the carriage 5 so that the recording head 6 is not tilted.

As described above, according to the test pattern formation and positional deviation detection operations of the present embodiment, the amount of deviation in image formation caused by the inclination of the recording head with respect to the carriage can be detected with high accuracy.

<Modifications regarding recording head adjustment>
In the above embodiment, the user manually adjusts the mounting position of the recording head 6, but an adjustment mechanism is provided that allows the position of the recording head 6 to be adjusted electrically, and the adjustment mechanism is based on the inclination angle θ. The recording head 6 may be configured to automatically adjust the mounting position of the recording head 6.

Further, the displacement of the ink landing position may be suppressed by adjusting the ejection timing of the nozzles 6a without changing the position of the recording head 6.

FIG. 13 is a block diagram showing a modified example of the functional configuration regarding detection of landing position deviation. In FIG. 13, a discharge timing adjustment section 410 is implemented in the CPU 101 instead of the information output section 403. The ejection timing adjustment unit 410 adjusts the recording so that the inclination angle θ of the reference marker Ks and the measurement marker Km formed on the recording paper P approaches 0, based on the inclination angle θ calculated by the inclination calculation unit 402. The ejection timing of each nozzle 6a included in the head 6 is changed. Specifically, the ejection timing adjustment section 410 changes the common drive waveform signal Vcom by instructing the recording head control section 116 to change the value of the above-mentioned ejection timing signal CHANGE based on the inclination angle θ. Adjust timing.

FIG. 14 is a diagram illustrating timing adjustment of the common drive waveform signal Vcom. When the value of the ejection timing signal CHANGE is the default value, the common drive waveform has a timing delayed by the default value from the LINE signal, which is the reference signal. The delay timing when the value of the ejection timing signal CHANGE is the default value is the reference timing shown in FIG. 14(a).

For example, if the default value of the delay amount is 7 as shown in FIG. 14(a), the value of the ejection timing signal CHANGE should be set larger than 7 (for example, 8 to 13) as shown in FIG. 14(b). Then, the ejection timing will be delayed.

On the other hand, as shown in FIG. 14(c), by setting the value of the ejection timing signal CHANGE to less than 7 (for example, 1 to 6), the ejection timing is accelerated. This allows fine ejection timing adjustment of one dot or less.

<Other modifications of the first embodiment>
In the above embodiment, the two-dimensional sensor 21 is used as an imaging means for imaging the test pattern TP, but since it is sufficient to measure the distance between the reference marker Ks and the measurement marker Km in the main scanning direction, photoelectric conversion is performed in the main scanning direction. It may be a one-dimensional sensor in which elements (for example, photodiodes) are arranged.

Alternatively, the above-mentioned captured image may be obtained by using a reflective photosensor including a light emitting element and a light receiving element as an imaging means and scanning the reflective photosensor with respect to the test pattern TP. good.

Furthermore, in the embodiment described above, after forming the first marker M1, the recording paper P is transported in the sub-scanning direction by the transport unit 150, but instead of the recording paper P, the recording head 6 is moved in the sub-scanning direction. It may also be configured to allow That is, in order to switch between the first nozzle group G1 used for forming the first marker M1 from the plurality of nozzles 6a and the second nozzle group G2 used for forming the second marker M2, the recording head 6 and the recording paper P It suffices if it is possible to move relatively in the sub-scanning direction.

Further, in the above embodiment, the arrangement pitch of the second markers M2 in the main scanning direction is twice the arrangement pitch of the first markers M1, but this magnification is not limited to 2, and may be an integral multiple. Furthermore, the first marker M1 and the second marker M2 do not need to be formed at a constant pitch (equal interval) in the main scanning direction, but may be formed in a known pattern.

Furthermore, in the above embodiment, the first marker M1 and the second marker M2 are each formed in a linear shape, but they do not necessarily have to be linear, and may be in the form of discrete dots or a single dot. .

[Second embodiment]
A liquid ejecting device according to a second embodiment of the present invention will be described below.

The liquid ejecting device according to the second embodiment can perform an ink landing position deviation detection operation when the recording head 6 moves forward and back, instead of the above-mentioned detection operation that detects the inclination of the recording head 6. shall be.

The configuration of the liquid ejecting device according to the second embodiment is basically the same as the configuration of the liquid ejecting device 1 according to the first embodiment, so a description thereof will be omitted.

FIG. 15 is a block diagram showing a functional configuration related to detection of landing position deviation according to the second embodiment. The functional configuration of this embodiment is the same as the functional configuration shown in FIG. 13 except that a shift amount calculation unit 420 is implemented instead of the slope calculation unit 402.

Next, with reference to FIGS. 16 to 18, the formation of the test pattern TP and the positional deviation detection operation in this embodiment will be described.

FIG. 16 is a diagram illustrating the formation operation of the first marker M1. FIG. 17 is a diagram illustrating the formation operation of the second marker M2. FIG. 18 is a flowchart illustrating the formation of the test pattern TP and the positional deviation detection operation.

In this embodiment, the test pattern TP is formed by a plurality of nozzles 6a constituting one nozzle row of the recording head 6. Note that the test pattern TP may be formed by some nozzles 6a in one nozzle row. Further, similarly to the first embodiment, the color of the ink forming the test pattern TP is not limited to black.

First, as shown in FIG. 16, the pattern forming unit 400 applies ink onto the recording paper P from the plurality of nozzles 6a while moving the recording head 6 from a predetermined starting position in the main scanning direction positive side (forward direction). By discharging, the first marker M1 is formed (step S20 in FIG. 18). In this embodiment, the pattern forming unit 400 forms the first markers M1 at a constant pitch in the main scanning direction. In an ideal state in which there is no deviation in the landing position of the ink, the distance between the first markers M1 in the main scanning direction is the ideal value a.

Next, in this embodiment, the recording paper P is not conveyed after forming the first marker M1, and as shown in FIG. The second marker M2 is formed by ejecting ink onto the recording paper P from the nozzle 6a (step S21). At this time, the pattern forming unit 400 forms the second markers M2 at formation positions that are partially thinned out at a predetermined thinning rate (for example, 2) from the plurality of formation positions of the first markers M1. In this embodiment, the pattern forming unit 400 forms the second markers M2 at twice the pitch of the first markers M1 so as to partially overlap the first markers M1. In an ideal state in which there is no deviation in the landing position of the ink, the second marker M2 is formed to almost completely coincide with the first marker M1.

Similar to the first embodiment, the recording paper P has a test pattern TP including a reference marker Ks consisting of a first marker M1 and a measurement marker Km consisting of a superimposed first marker M1 and a second marker M2. It is formed.

FIG. 17 shows a case where a positional shift occurs in the landing position of the ink during the forward movement and the backward movement, and the positional deviation amount in the main scanning direction is δ.

This test pattern TP is imaged by the two-dimensional sensor 21, and the captured image is input to the two-dimensional sensor CPU 23 (step S22).

The interval measurement unit 404 executes the same process as in the first embodiment based on the captured image, thereby determining the interval b between the reference marker Ks and the first measurement marker and the interval b between the reference marker Ks and the second measurement marker. c (step S23).

A ratio r (=b/c) is calculated based on the measured values of the distances b and c measured by the distance measurement unit 404 (step S24).

The deviation amount calculation unit 420 uses the ratio r calculated by the ratio calculation unit 405 and the ideal value a of the interval obtained from the pattern forming unit 400, and calculates the deviation amount δ based on the above equation (3). Calculate (step S25).

The ejection timing adjustment unit 410 changes the ejection timing of each nozzle 6a included in the recording head 6 based on the deviation amount δ calculated by the deviation amount calculation unit 420 so that the deviation amount δ approaches 0. The method of timing adjustment by the ejection timing adjustment section 410 is the same as in the first embodiment.

As described above, according to the test pattern TP formation and positional deviation detection operations of this embodiment, the amount of deviation in image formation caused by the reciprocating movement of the recording head can be detected with high accuracy.

<Modified example of second embodiment>
The second embodiment can also be modified in the same way as the first embodiment, such as modification of the imaging means and the arrangement pitch of the second markers relative to the arrangement pitch of the first markers.

Further, the liquid ejecting device may be configured to be able to perform both the test pattern TP formation and positional deviation detection operations in the first embodiment and the second embodiment.

<Modifications regarding reference frame>
Next, as a modification of the first embodiment and the second embodiment, an example in which a reference frame F is formed to surround the test pattern TP will be described.

FIG. 19 is a diagram showing an example of the test pattern TP and the reference frame F. The reference frame F is formed on the recording paper P by the process of the pattern forming section 400. The reference frame F is formed of, for example, a thicker line than the test pattern TP. The test pattern TP and the reference frame F are imaged by the two-dimensional sensor 21.

The reference frame F is used when the distance measurement unit 404 measures the distance between the reference marker Ks and the measurement marker Km based on the captured image. Specifically, the interval measuring unit 404 performs a determination process based on the reference frame F shown in FIG. 20. First, the interval measurement unit 404 acquires a captured image captured by the two-dimensional sensor 21 (step S30). Next, the interval measurement unit 404 analyzes the captured image and determines whether the reference frame F exists within the captured image (step S31). If the reference frame F exists (step S31: Yes), the interval measuring unit 404 determines whether the reference marker Ks and the measurement marker Km exist within the reference frame F (step S32). If the reference marker Ks and the measurement marker Km are present (step S32: Yes), the interval measurement unit 404 determines that it is normal (step S33).

On the other hand, when the reference frame F does not exist within the captured image (step S31: No), and when the reference marker Ks and the measurement marker Km do not exist within the reference frame F (step S32: No), the interval measuring unit 404 is determined to be abnormal (error) (step S34).

When determining that the distance is normal, the distance measurement unit 404 performs the process of measuring the distance between the reference marker Ks and the measurement marker Km described above. On the other hand, if the interval measurement unit 404 determines that there is an abnormality, it ends the process.

The interval measuring unit 404 detects the positions of the reference marker Ks and the measurement marker Km based on the position of the reference frame F, so that even if the position where the test pattern TP is formed is shifted, the distance measurement unit 404 can detect the positions of the reference marker Ks and the measurement marker Km based on the position of the reference frame F. The location can be easily detected.

Note that the reference frame F may be formed in any order before the test pattern TP is formed or after the test pattern TP is formed.

Further, the test pattern TP in the first embodiment and the second embodiment only needs to include at least one reference marker and one measurement marker. Further, the ratio calculation unit 405 is not essential, and it is possible to calculate the deviation amount δ and the inclination angle θ based on the actually measured value of the interval.

In each of the above embodiments, the liquid ejection device of the present invention has been described using an example in which it is applied to an inkjet printer, but the invention is not limited to inkjet printers, and can also be applied to 3D printers and the like.

The liquid ejection device may have the following configuration, for example.

FIG. 21 is an example of a diagram illustrating the operation of the carriage in more detail. In this example, the guide rod 501 and the sub-guide 502 are spanned between the left side plate 503 and the right side plate 504. The carriage 505 slidably holds the guide rod 501 and the sub-guide 502 by a bearing 512 and a sub-guide receiving portion 511, and is movable in the directions of arrows X1 and X2 (main scanning direction).

The carriage 505 is equipped with print heads 521 and 522 that eject black (K) droplets, and print heads 523 and 524 that eject cyan (C), magenta (M), and yellow (Y) ink droplets. has been done. The recording head 521 is arranged because black is often used, and can be omitted.

Note that the recording heads 521 to 524 use piezoelectric elements as pressure generating means (actuator means) for pressurizing ink in the ink flow path (pressure generation chamber) to deform a diaphragm that forms the wall surface of the ink flow path. A so-called piezo type device that uses a heating resistor to eject ink droplets by changing the internal volume of the ink flow path, and uses a heating resistor to heat the ink within the ink flow path and generate air bubbles to eject ink droplets with pressure. The ink flow path can be created using a so-called thermal type, or by arranging a diaphragm that forms the wall surface of the ink flow path and an electrode facing each other, and deforming the diaphragm by electrostatic force generated between the diaphragm and the electrode. An electrostatic type in which ink droplets are ejected by changing the internal volume can be used.

A main scanning mechanism 532 that moves and scans the carriage 505 includes a main scanning motor 508 disposed on one side in the main scanning direction, a drive pulley 507 rotationally driven by the main scanning motor 508, and a drive pulley 507 disposed on the other side in the main scanning direction. The timing belt 509 is provided with a pressure roller 515 and a timing belt 509 stretched between the drive pulley 507 and the pressure roller 515. Note that the pressure roller 515 is tensioned outwardly (in the direction away from the drive pulley 507) by a tension spring.

A portion of the timing belt 509 is fixedly held by a belt holding portion 510 provided on the back side of the carriage 505, so that the timing belt 509 pulls the carriage 505 in the main scanning direction as the timing belt 509 moves endlessly.

Further, an encoder sheet 541 is arranged along the main scanning direction of the carriage 505, and by reading the slit of the encoder sheet 541 with an encoder sensor 542 provided on the carriage 505, the position of the carriage 5 in the main scanning direction can be determined. Can be detected. When this carriage 505 exists in the recording area of the main scanning area, the sheet material is intermittently conveyed by the paper feeding mechanism in the arrow Y1 and Y2 directions (sub-scanning direction) perpendicular to the main scanning direction of the carriage 505. .

In the image forming apparatus according to the present embodiment described above, the carriage 505 moves in the main scanning direction. Then, by intermittently feeding the sheet material and driving the recording heads 521 to 524 according to the image information to eject droplets, a desired image can be formed on the sheet material and printed matter can be manufactured. .

A print position shift sensor 530 is mounted on one side of the carriage 505 to detect a shift in the landing position (read a test pattern). The print position deviation sensor 530 reads a test pattern for detecting the landing position formed on the sheet material using a light receiving element composed of a light emitting element such as an LED and a reflective photosensor.

Since this print position deviation sensor 530 is for the print head 521, another print position deviation sensor 530 may be mounted in parallel with the print heads 522 to 524 in order to adjust the droplet ejection timing of the print heads 522 to 524. preferable. Furthermore, if the carriage 505 is equipped with a mechanism that slides the print position deviation sensor 530 so that it is parallel to the print heads 522 to 524, one print position deviation sensor 530 can eject droplets from the print heads 522 to 524. You can adjust the timing. Alternatively, even if the image forming apparatus sends the sheet material in the opposite direction, the timing of ejecting droplets from the recording heads 522 to 524 can be adjusted using one print position deviation sensor 530.

FIG. 22 is an example of a diagram schematically showing a configuration for the print position deviation sensor to detect the edge position of the test pattern. FIG. 22 is a diagram of the recording head 521 and print position deviation sensor 530 shown in FIG. 21 as viewed from the right side plate 504.

The print position shift sensor 530 includes a light emitting element 601, a light receiving element 602, and a light receiving element 603 that are arranged in a direction perpendicular to the main scanning direction. The arrangement of the light emitting element 601 and the light receiving elements 602 and 603 may be reversed. The light emitting element 601 projects spot light onto the test pattern 400a, and one of the light receiving elements 602 and 603 receives the specularly reflected light reflected from the sheet material 650, and the other receives the specularly reflected light reflected from the platen. It receives light and other diffusely reflected light such as scattered light. The light emitting element 601 and the light receiving elements 602 and 603 are fixed inside the housing. Further, the surface of the print position deviation sensor facing the platen is shielded from the outside by a lens 604 or the like. In this way, the print position deviation sensor 530 is packaged and can be distributed alone.

In the print position deviation sensor, a light emitting element 601, a light receiving element 602, and a light receiving element 603 are arranged in a direction perpendicular to the scanning direction of the carriage 505 (arranged in parallel to the sub-scanning direction). This makes it possible to reduce the influence of fluctuations in the moving speed of the carriage 505 on the detection results.

For example, an LED can be used as the light emitting element 601, but any light source capable of projecting visible light (for example, a laser or various lamps) may be used. The reason for using visible light is to expect that the spot light will be absorbed by the test pattern. Note that, although the wavelength of the light emitting element 601 is fixed, it is also possible to mount a plurality of print position shift sensors 530 equipped with light emitting elements 601 having different wavelengths.

Further, the spot diameter formed by the light emitting element 601 is on the order of mm in order to use an inexpensive lens instead of a high-precision lens. This spot diameter is related to the detection accuracy of the edge of the test pattern, but even if the spot diameter is on the order of mm, the edge position can be detected with sufficiently high accuracy using the method of determining the edge position of this embodiment. However, it is also possible to make the spot diameter smaller.

The CPU 605 starts correcting the landing position deviation at a predetermined timing. This timing may be, for example, the timing when the user instructs the correction of the landing position deviation from the operation/display unit, or the CPU 605 determines a specific timing because the light emitting element 601 emits light before ink is ejected and the intensity of the reflected light at that time is below a predetermined value. The timing at which it was determined that the material was sheet material 650, the temperature and humidity at the time of the last impact position deviation correction were memorized, and the timing at which it was determined that either the temperature or humidity deviated by more than a threshold value, and the periodic (daily, weekly) , every month, etc.).

The landing position deviation correction of this embodiment includes two stages of processing: before and after forming the test pattern. However, the main difference is whether a test pattern is formed or not, so the case where a test pattern is formed will be explained here.

The CPU 605 instructs the main scanning drive unit and the like to move the carriage 505 back and forth, and instructs the head drive control circuit 606 to eject droplets using a predetermined test pattern as print data. The main scanning drive section moves the carriage 505 back and forth in the main scanning direction with respect to the sheet material 650, and the head drive control circuit 606 causes droplets to be ejected from the recording head 521 to form at least two or more independent droplets. Form a test pattern including lines.

Further, the CPU 605 performs control to read the test pattern formed on the sheet material 650 using a print position deviation sensor. Specifically, the CPU 605 sets a PWM value (mainly duty) in the light emission control device 607 for driving the light emitting element 601 of the print position deviation sensor. Then, the light emission control device 607 creates a PWM signal according to the PWM value in the PWM signal creation circuit 608. A PWM signal created by a PWM signal creation circuit 608 is smoothed by a smoothing circuit 609 and then provided to a drive circuit 610 . The drive circuit 610 drives the light emitting element 601 to emit light, and the test pattern on the sheet material 650 is irradiated with spot light from the light emitting element 601 . Note that the light emission control device 607, the smoothing circuit 609, the drive circuit 610, the photoelectric conversion circuit 611, the low-pass filter circuit 612, the A/D conversion circuit 613, and the correction processing execution unit 614 are installed in the main control unit or the control unit, etc. Ru. The shared memory 615 is, for example, a RAM or the like.

When the test pattern on the sheet material is irradiated with spot light from the light emitting element 601, reflected light reflected from the test pattern enters the light receiving elements 602 and 603. The light receiving elements 602 and 603 output intensity signals of reflected light to the photoelectric conversion circuit 611. The photoelectric conversion circuit 611 is capable of switching the magnification registers of the light receiving elements 602 and 603, as will be described later. The magnification register has, for example, 4 to 16 bits, and increases the output voltage of the light receiving elements 602 and 603 according to the set value. For example, in the case of 4 bits, "0001" is the normal state, setting it to "0010" doubles the output voltage, and setting it to "0011" triples the output voltage. Alternatively, an arbitrary magnification may be set, such as setting the output voltage to 1.5 times when it is set to "0010" and doubling the output voltage when it is set to "0011". By increasing the magnification in this way, the sensitivity of the light receiving elements 602 and 603 can be increased.

Specifically, the photoelectric conversion circuit 611 photoelectrically converts the intensity signal and outputs this photoelectric conversion signal (sensor output voltage) to the low-pass filter circuit 612. After removing high-frequency noise, the low-pass filter circuit 612 outputs a photoelectric conversion signal to the A/D conversion circuit 613. The A/D conversion circuit 613 A/D converts the photoelectric conversion signal and outputs it to a signal processing circuit (such as an FPGA 616). The signal processing circuit stores output voltage data, which is a digital value of the A/D converted output voltage, in the shared memory 615.

The correction processing execution unit 614 reads out the output voltage data stored in the shared memory 615 , performs landing position deviation correction, and sets it in the head drive control circuit 606 . That is, the correction processing execution unit 614 detects the edge position of the test pattern and compares it with the appropriate distance between two lines, thereby calculating the landing position deviation amount. The correction processing execution unit 614 is realized by the CPU 605 executing a program or by an IC or the like.

The correction processing execution unit 614 calculates the amount of correction of the droplet ejection timing when driving the print head so that the landing position deviation is eliminated, and sets the calculated amount of correction of the droplet ejection timing in the head drive control circuit 606. . Sensor calibration, which will be described later, is also performed by the correction processing execution unit 614. As a result, when driving the print head, the head drive control circuit 606 corrects the droplet ejection timing based on the correction amount before driving the print head, so it is possible to reduce the deviation in the droplet landing position. can.

Note that the sensor serving as the reading means is not limited to the example shown above, and may be a one-dimensional sensor or a two-dimensional sensor as long as the position where the liquid has landed can be read based on a pattern such as a test pattern.

Further, it is preferable that the reading means includes an imaging means. That is, for example, the reading means is realized by an optical sensor or the like. On the other hand, the reading means may be realized by a reading unit realized by a type of sensor other than an optical sensor, or by a combination of an optical sensor and another type of sensor, as long as a pattern such as a marker can be read. .

Furthermore, the present invention is not limited to the requirements shown in each of the above embodiments. These points can be changed without detracting from the gist of the present invention, and can be determined appropriately depending on the application thereof.

1 Liquid discharge device 5 Carriage 6 Recording head 6a Nozzle 7 Cartridge 13 Encoder sensor 14 Encoder sheet 20 Imaging section 21 Two-dimensional sensor (imaging means)
150 Transport unit (medium moving means)
400 Pattern forming section (pattern forming means)
401 Transport control section 402 Inclination calculation section (inclination calculation means)
403 Information output unit (information output means)
404 Interval measurement unit (interval measurement means)
405 Ratio calculation unit (ratio calculation means)
410 Discharge timing adjustment section (discharge timing adjustment means)
420 Displacement amount calculation unit (displacement amount calculation means)

JP2018-83405A

Claims (20)

A recording head that discharges liquid is moved in a first direction relative to the recording medium to form at least three first markers, and a first marker is formed at two of the three first marker formation positions. A pattern comprising two markers, a reference marker consisting of only the first marker, and a pair of measurement markers formed by overlapping the first marker and the second marker and sandwiching the reference marker. pattern forming means for forming;
reading means for reading the pattern;
distance measuring means for measuring the distance between the reference marker and the measurement marker in the first direction from the information read by the reading means;
A liquid ejection device having: The pattern forming means forms a plurality of the first markers in the first direction at a constant pitch, and forms a plurality of the second markers in the first direction at a pitch that is an integral multiple of the pitch. 2. The liquid ejecting device according to claim 1, wherein the liquid ejecting device is formed at a part of the forming position. The liquid ejecting device according to claim 2, wherein the pitch of the second marker is twice the pitch of the first marker. One of the pair of measurement markers is a first measurement marker and the other is a second measurement marker, and the distance between the reference marker and the first measurement marker and the distance between the reference marker and the second measurement marker are The liquid ejection device according to claim 3, further comprising ratio calculation means for calculating the ratio. The recording head has a plurality of nozzles that eject liquid arranged in a second direction perpendicular to the first direction,
The liquid ejecting device according to claim 4, wherein the first marker and the second marker are formed by liquid ejected from the same or different nozzles among the plurality of nozzles. further comprising medium moving means for moving the recording medium in the second direction relative to the recording head,
The pattern forming means forms the first marker, and after the recording medium is moved by a predetermined movement amount by the medium moving means, the pattern forming means forms the second marker using a nozzle different from the nozzle that formed the first marker. 6. The liquid ejecting device according to claim 5, wherein the liquid ejecting device forms: 7. The liquid ejecting apparatus according to claim 6, further comprising an inclination calculation means for calculating an inclination angle of the recording head using the ratio, the interval between the first markers, and the movement amount. The liquid ejection device according to claim 7, further comprising information output means for outputting information regarding the inclination angle. 8. The liquid ejection apparatus according to claim 7, further comprising ejection timing adjustment means for adjusting ejection timing by the recording head based on the inclination angle. The pattern forming means forms the first marker while moving the recording head in the positive side of the first direction, and forms the second marker while moving the recording head in the negative side of the first direction. It is something that
6. The method according to claim 5, further comprising a deviation amount calculation means for calculating an amount of deviation between the formation positions of the first marker and the second marker in the first direction using the ratio and the interval between the first markers. The liquid ejection device described. 11. The liquid ejection apparatus according to claim 10, further comprising ejection timing adjusting means for adjusting ejection timing by the recording head based on the amount of deviation. 12. The liquid ejecting device according to claim 5, wherein the pattern forming means forms the first marker and the second marker in a linear shape extending in the second direction. 13. The liquid ejecting device according to claim 1, wherein the pattern forming means forms a reference frame to surround the pattern. 14. The liquid ejecting device according to claim 1, wherein the reading means includes an imaging means. 15. The liquid ejecting device according to claim 14, wherein the interval measuring means determines the interval by measuring the distance between peaks in the first direction in the density distribution of the image taken by the imaging means. A recording head that discharges liquid is moved in a first direction relative to the recording medium to form at least three first markers, and a first marker is placed at one formation position of the three first markers. 2 markers are formed, including two reference markers consisting only of the first marker, and a measurement marker formed between the two reference markers in which the first marker and the second marker are layered. a pattern forming means for forming a pattern;
reading means for reading the pattern;
distance measuring means for measuring the distance between the reference marker and the measurement marker in the first direction from the information read by the reading means;
A liquid ejection device having: A recording head that discharges liquid is moved in a first direction relative to the recording medium to form at least three first markers, and a first marker is formed at two of the three first marker formation positions. A pattern comprising two markers, a reference marker consisting of only the first marker, and a pair of measurement markers formed by overlapping the first marker and the second marker and sandwiching the reference marker. a pattern forming step to form a
a reading step of reading the pattern;
an interval measuring step of measuring an interval between the reference marker and the measurement marker in the first direction from the information read in the reading step;
A liquid discharging method having the following. A recording head that discharges liquid is moved in a first direction relative to the recording medium to form at least three first markers, and a first marker is placed at one formation position of the three first markers. 2 markers are formed, including two reference markers consisting only of the first marker, and a measurement marker formed between the two reference markers in which the first marker and the second marker are layered. a pattern forming step of forming a pattern;
a reading step of reading the pattern;
an interval measuring step of measuring an interval between the reference marker and the measurement marker in the first direction from the information read in the reading step;
A liquid discharging method comprising: computer,
A recording head that discharges liquid is moved in a first direction relative to the recording medium to form at least three first markers, and a first marker is formed at two of the three first marker formation positions. A pattern comprising two markers, a reference marker consisting of only the first marker, and a pair of measurement markers formed by overlapping the first marker and the second marker and sandwiching the reference marker. a pattern forming section that forms a
a reading unit that reads the pattern;
an interval measuring unit that measures an interval between the reference marker and the measurement marker in the first direction from information read by the reading unit;
A program that makes it work. computer,
A recording head that discharges liquid is moved in a first direction relative to the recording medium to form at least three first markers, and a first marker is placed at one formation position of the three first markers. 2 markers are formed, including two reference markers consisting only of the first marker, and a measurement marker formed between the two reference markers in which the first marker and the second marker are layered. a pattern forming section that forms a pattern;
a reading unit that reads the pattern;
an interval measuring unit that measures an interval between the reference marker and the measurement marker in the first direction from information read by the reading unit;
A program that makes it work.

Images