JP5374954B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus preventing positional deviation of a recording image due to abrasion or chipping of a bearing part of a carriage or a sliding shaft caused by a change in the lapse of time. <P>SOLUTION: The image forming apparatus includes: a detection means in which reference images S11 to S13 obtained by image-capturing reference patterns disposed in the apparatus body by the use of an imaging sensor in the initial time as usage record of the carriage or the sliding shaft and calibrated images S21 to S23 obtained by image-capturing the reference patterns by the use of the imaging sensor with a prescribed timing as the usage record of the carriage or the sliding shaft are compared to each other and, thereby, an inclination amount against the sliding shaft of the carriage (carriage inclination amount) is detected (S25); and a correction means by which the driving of a recording head is corrected by using the detected carriage inclination amount (S27). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus such as an ink jet recording apparatus.

  In general, as an image forming apparatus that combines a printer / fax / copier or a combination of these functions, an image forming unit that employs an electrophotographic method is known. For example, liquid discharge that discharges liquid droplets of recording liquid is known. Recording is performed while a recording medium (hereinafter also referred to as “paper” is not limited to a material, and the recording medium, a transfer material, and the like are also used synonymously) using a recording head constituted by a head. Equipped with an inkjet image forming unit that forms liquid (ink) droplets (hereinafter also referred to as ink droplets) on paper and forms images (recording, printing, printing, and printing are also synonymous). Some have done.

  In such an ink-jet image forming apparatus, a carriage having a recording head is reciprocated in the main scanning direction, and recording is performed by intermittently feeding a recording medium in the sub-scanning direction. Specifically, when scanning the carriage mounted with the recording head in the forward path and the backward path, the encoder scale arranged in the main scanning direction is read by an optical sensor, the positional information of the carriage is acquired, and from the recording head based on this positional information Is generated, and ink is discharged from the recording head in accordance with the discharge timing to perform recording.

  Here, in a conventional image forming apparatus, as a configuration of ejection control for a decrease in print quality due to secular change, an inkjet head, a drive signal recording unit that stores a plurality of drive signals, and a panel that can select a drive signal are provided. There is an example in which the carriage discharge control is enabled by recognizing the poor print quality by calling a drive condition change menu from the operation panel and selecting a drive signal different from the default drive signal. This drive signal is data determined in advance based on experiments and past experiences, and discharge control is performed by adjusting the discharge timing for each signal.

However, in the case of the above control method, the following problems occur.
(1) In order to perform more accurate discharge control, it is necessary to obtain drive signals under various conditions, and it takes a lot of time to create a database of drive signals including experiments, which is difficult in terms of cost. is there.
(2) It is necessary to judge the deterioration of the image quality due to secular change by the user's subjectivity. That is, there is a possibility that the image quality varies for each user, and it is difficult to obtain a certain and stable image formation.

  Patent Document 1 proposes the following configuration for the purpose of improving the ink ejection accuracy with respect to secular change. In other words, a light receiving sensor fixed at a position having a certain distance from the medium is arranged on a carriage that drives printing in the main scanning direction, and at the time of shipment from the factory, the light receiving sensor displays the discharge pattern by a carriage driving method that does not control discharge over time. The pattern position information (pitch) is acquired and recorded as an initial value on the main body. On the other hand, with the device printed in various printing environments and states by the user, the same discharge accuracy (position information) in the main scanning direction as that at the time of shipment is detected for each ink discharge corresponding to the preset number of prints. The difference in position information between the discharge pattern (initial value) at the time of shipment from the factory and the discharge pattern for each set number of sheets is calculated as the discharge accuracy difference (position shift) in the entire range of the carriage drive range, and the difference is determined as the discharge timing. It is possible to adjust with. Thus, in order to obtain a higher quality image formation, the user can select and change the set number of ejection patterns to be detected, and the recording apparatus can also be used when the user needs ejection accuracy in each case. It is possible to have a mode in which the discharge accuracy pattern is read by selecting the mode with the operation unit provided and the latest discharge control can be performed.

  However, this technique only detects the positional deviation of the recorded image in the main scanning direction, and detects the positional deviation of the recorded image in other directions that may occur due to shaving of the carriage bearing or sliding shaft due to aging. It was not possible to prevent image quality deterioration.

JP 2007-185870 A

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems in the prior art, and prevents image displacement of a recorded image over time due to wear or scraping of a bearing portion or a sliding shaft of a carriage due to aging. The purpose is to provide.

The present invention provided to solve the above problems is as follows.
[1] a carriage for mounting a recording head for forming an image on a recording medium by ejecting ink, scanning in the direction orthogonal to the carriage along a sliding axis in the conveying Direction of the recording medium in the image forming apparatus having a scanning unit, a position information acquisition means for acquiring position information of the carriage on the basis of the first pattern provided on the image forming instrumentation 置内 and the carriage is mounted on the carriage imaging means for imaging a second pattern provided on the image forming apparatus when comes to a predetermined position acquired by the position information acquiring unit, the second pattern in advance the imaging means at the predetermined position A comparison between a reference image obtained by imaging and a calibration image obtained by imaging the second pattern by the imaging means at the predetermined position, and sliding the carriage An image forming apparatus comprising: a detecting unit configured to detect an amount of inclination with respect to an axis, and forming an image based on an amount of inclination with respect to the sliding axis of the carriage and position information of the carriage .
[2] The image forming apparatus according to [1], wherein the first pattern is a pattern recorded at equal intervals that is read by a sensor provided on the carriage.
[3] The image forming apparatus according to [1] or [2], wherein the reference image is an image obtained by photographing the second pattern by the imaging unit at an initial stage of use of the carriage.
[ 4 ] The image forming apparatus according to any one of [1] to [3 ], wherein the second pattern is provided at a position facing the imaging unit.
[ 5 ] The image forming apparatus according to any one of [1] to [4 ], wherein the second pattern includes a plurality of linear marks extending at least one in each of two orthogonal directions.
[6] the imaging means, the image forming apparatus according to any one of [1] which is positioned farthest from the bearing portion of the sliding shaft in key Yarijji outer surface to [5].
[ 7 ] The image forming apparatus according to any one of [1] to [6] , wherein the imaging unit is an area sensor or a line sensor.
[ 8 ] The detection means compares the calibration image with a reference image, determines the type of inclination with respect to the sliding axis of the carriage, and calculates the amount of carriage inclination for each type of inclination . [7] The image forming apparatus according to any one of [7] .
[9] before SL using the carriage inclination amount, the image forming apparatus according to any one of forming an image by correcting the ejection timing of ink from the recording head from [1] to [8].

  According to the present invention, it is possible to calculate the amount of inclination of the carriage in a plurality of directions from the initial posture of the carriage by imaging the reference pattern provided on the image forming apparatus main body side by the imaging means (sensor) attached to the carriage. It is possible to prevent the positional deviation of the recorded image (printing) over time based on the detection result.

The image forming apparatus according to the present invention will be described below.
FIG. 1 is an explanatory perspective view of an ink jet recording apparatus, which is an aspect of an image forming apparatus according to the present invention, as viewed from the front side.
The ink jet recording apparatus includes an apparatus main body 1, a paper feed tray 2 for loading paper loaded in the apparatus main body 1, and a sheet on which an image is recorded (formed) by being detachably mounted on the apparatus main body 1. A paper discharge tray 3 for stocking is provided. Further, a cartridge loading for loading an ink cartridge that protrudes from the front surface to the front side of the apparatus main body 1 and is lower than the upper surface is provided at one end side of the front surface of the apparatus main body 1 (side of the paper supply / discharge tray section). The cartridge loading unit 4 has an operation / display unit 5 provided with operation buttons and a display.

  The cartridge loading unit 4 contains a plurality of recording liquids (inks) that are different color materials, such as black (K) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink. Ink cartridges 10k, 10c, 10m, 10y (referred to as “ink cartridge 10” when colors are not distinguished) from the front side to the rear side of the apparatus main body 1 A front cover (cartridge cover) 6 that is opened when the ink cartridge 10 is attached or detached is provided on the front side of the cartridge loading portion 4 so as to be openable and closable. Further, the ink cartridges 10k, 10c, 10m, and 10y are configured to be loaded side by side in a vertical state.

  Further, the operation / display unit 5 includes ink remaining amounts of the ink cartridges 10k, 10c, 10m, and 10y of the respective colors at the arrangement positions corresponding to the mounting positions (arrangement positions) of the ink cartridges 10k, 10c, 10m, and 10y of the respective colors. Are arranged for displaying the remaining amount display portions 11k, 11c, 11m, and 11y for each color (when the colors are not distinguished, they are referred to as “remaining amount display portion 11”). Further, the operation / display unit 5 is also provided with a power button 12, a paper feed / print resume button 13, and a cancel button 14.

Next, the mechanism part of the ink jet recording apparatus will be described with reference to FIGS. FIG. 2 is a schematic side view illustrating the outline of the mechanism, and FIG.
A guide rod 31, which is a sliding shaft (guide member) horizontally mounted on the left and right side plates 21 </ b> A and 21 </ b> B constituting the frame 21, is inserted into the bearing portion of the carriage 33, and the carriage 33 is formed by the guide rod 31 and the stay 32. Are slidable in the main scanning direction. A main scanning motor (not shown) moves and scans in a direction indicated by an arrow (carriage main scanning direction) in FIG. 3 via a timing belt.

  As described above, the carriage 33 includes a recording head 34 including four droplet discharge heads that discharge ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk). A plurality of ink ejection openings are arranged in a direction crossing the main scanning direction, and are mounted with the ink droplet ejection direction facing downward.

  As an inkjet head constituting the recording head 34, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. It is possible to use a shape memory alloy actuator to be used, an electrostatic actuator using an electrostatic force, or the like provided as pressure generating means for generating a pressure for discharging a droplet.

  A driver IC is mounted on the recording head 34 and is connected to a control unit (not shown) via a harness (flexible print cable) 22.

  In addition, the carriage 33 is equipped with a recording head 34 and sub tanks 35 for each color for supplying ink of each color to the recording head 34 as image forming means. As described above, each color sub-tank 35 is supplementarily supplied with ink of each color from the ink cartridge 10 of each color mounted in the cartridge loading unit 4 in a one-to-one relationship via the ink supply tube 36 of each color. Is done. The cartridge loading unit 4 is provided with a supply pump 24 for feeding the ink in the ink cartridge 10, and the ink supply tube 36 is engaged with the rear plate 21 </ b> C constituting the frame 21 in the middle of turning. It is held by a stop member 25.

  The position information of the carriage 33 is a pattern recorded at regular intervals on an encoder scale (not shown, also referred to as an absolute position pattern) fixed to the apparatus housing, and a main scanning encoder sensor (hereinafter referred to as an encoder) fixed to the carriage 33. A sensor (also referred to as a transmission type sensor) (not shown) reads while moving and outputs it as an encoder signal.

  On the other hand, as a paper feeding unit for feeding the papers 42 stacked on the paper stacking unit (pressure plate) 41 of the paper feeding tray 2, a half-moon roller (feeding) that separates and feeds the papers 42 one by one from the paper stacking unit 41. A separation pad 44 made of a material having a large friction coefficient is provided facing the paper roller 43) and the paper feed roller 43, and the separation pad 44 is urged toward the paper feed roller 43 side.

  In order to feed the paper 42 fed from the paper feeding unit to the lower side of the recording head 34, a guide member 45 for guiding the paper 42, a counter roller 46, a transport guide member 47, and a tip pressure roller. And a holding belt 48 which is a conveying means for electrostatically attracting the fed paper 42 and conveying it at a position facing the recording head 34.

  The transport belt 51 is an endless belt, and is configured to wrap around the transport roller 52 and the tension roller 53 and circulate in the belt transport direction (sub-scanning direction). Further, a charging roller 56 that is a charging unit for charging the surface of the transport belt 51 is provided. The charging roller 56 is disposed so as to come into contact with the surface layer of the transport belt 51 and to rotate following the rotation of the transport belt 51. Further, a guide member 57 is disposed on the back side of the conveyor belt 51 in correspondence with a printing area by the recording head 34.

  The conveyance belt 51 rotates in the belt conveyance direction (sub-scanning direction) in FIG. 3 when the conveyance roller 52 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 42 recorded by the recording head 34, a separation claw 61 for separating the paper 42 from the conveying belt 51, a paper discharge roller 62, and a paper discharge roller 63 are provided. The paper discharge tray 3 is provided below the paper discharge roller 62.

  A duplex unit 71 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 71 takes in the paper 42 returned by the reverse rotation of the conveyance belt 51, reverses it, and feeds it again between the counter roller 46 and the conveyance belt 51. The upper surface of the duplex unit 71 is a manual feed tray 72.

  Further, as shown in FIG. 3, in the non-printing area on one side (right side in the drawing) of the carriage 33 in the scanning direction (main scanning direction), the recovery means for maintaining and recovering the nozzle state of the recording head 34 A maintenance / recovery mechanism 81 is disposed.

  The maintenance / recovery mechanism 81 includes cap members (hereinafter referred to as “caps”) 82a to 82d (hereinafter referred to as “caps 82” when not distinguished from each other) for capping the nozzle surfaces of the recording head 34, and nozzle surfaces. A wiper blade 83 that is a blade member for wiping the ink, and an empty discharge receiver 84 that receives liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid. ing. Here, the cap 82a is a suction and moisture retention cap, and the other caps 82b to 82d are moisture retention caps.

  Further, as shown in FIG. 3, in the non-printing area on the other side (left side in the figure) of the carriage 33 in the scanning direction, liquid droplets that do not contribute to recording are discharged in order to discharge the recording liquid thickened during recording. An empty discharge receiver 88 that receives liquid droplets when performing empty discharge is disposed, and the empty discharge receiver 88 is provided with an opening 89 along the nozzle row direction of the recording head 34.

  In the ink jet recording apparatus configured as described above, the sheets 42 are separated and fed one by one from the sheet feeding tray 2, and the sheet 42 fed substantially vertically upward is guided by the guide 45, and the transport belt 51 and the counter roller 46, and the leading end is guided by the conveying guide 47 and pressed against the conveying belt 51 by the leading end pressing roller 49, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately repeated with respect to the charging roller 56, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 51 alternates, that is, in a sub-scanning direction that is a circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width. When the paper 42 is fed onto the conveyance belt 51 charged alternately with plus and minus, the paper 42 is attracted to the conveyance belt 51, and the paper 42 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 51.

  When forming a dot image (recorded image, also simply referred to as an image), the carriage 33 is moved (scanned) in the main scanning direction by the scanning means while obtaining the positional information of the carriage 33 by an encoder sensor, and at a necessary position. Ink droplets are ejected onto the paper 42 on the conveyor belt 51. At this time, by performing the ink ejection operation once while moving the carriage 33 in the main scanning direction, it is possible to form a dot image for a band having the same width as the length of the nozzle row, and image formation for one band. Is completed, the sub-scanning motor (not shown) is driven to move the paper 42 in the sub-scanning direction, and the image forming operation for one band is repeated to form an image at an arbitrary position on the paper 42. can do. Upon receiving a recording end signal or a signal that the trailing edge of the paper 42 has reached the recording area, the recording operation is finished and the paper 42 is discharged onto the paper discharge tray 3.

  Further, during printing (recording) standby, the carriage 33 is moved to the maintenance / recovery mechanism 81 side, and the recording head 34 is capped by the cap 82 to keep the nozzles in a wet state, thereby preventing ejection failure due to ink drying. . Further, the recording liquid is sucked from the nozzle by a suction pump (not shown) with the recording head 34 capped by the cap 82 (referred to as “nozzle suction” or “head suction”), and the thickened recording liquid and bubbles are discharged. Perform recovery action. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. As a result, the stable ejection performance of the recording head 34 is maintained.

Next, an outline of the control unit of the ink jet recording apparatus shown in FIGS. 1 to 3 will be described with reference to FIG. This figure is an overall block diagram of the control unit.
The control unit 100 is a unit that controls the entire apparatus, a unit that controls a conveyance operation of the paper 42 and a movement operation of the recording head 34, a CPU 101 that also performs arithmetic processing, a program executed by the CPU 101, other data, and the like ROM 102 for storing fixed data, RAM 103 used for a buffer for temporarily storing work areas and image data used for computation, and machine information (version and machine-specific characteristics) even while the apparatus is powered off. Non-volatile memory (NVRAM) 104 for holding data, etc., image processing for performing various signal processing, rearrangement, etc. and other device control (mechanical control, memory control, I / F control with CPU 101) ASIC 105 for processing input / output signals for

  The control unit 100 also generates a drive waveform for driving the host I / F 106 that receives a print job from the host PC 90 that is a data processing apparatus such as a personal computer on which a printer driver can be mounted, and the recording head 34. The main scanning for driving the waveform generation unit 107, the head driver 108 for controlling the driving of the pressure generating means of the recording head 34 by receiving the driving waveform from the driving waveform generation unit 107, and the main scanning motor 110 for scanning the carriage 13. An AC bias is supplied to the motor driving unit 111, the sub-scanning motor driving unit 113 that drives the sub-scanning motor 112 for rotating the conveying belt 51 that conveys the paper 42, and the charging roller 56 that charges the conveying belt 51. The recording head 3 includes a bias supply unit 114 and a maintenance / recovery mechanism 81 in the apparatus. A maintenance / recovery mechanism driving unit 115 for driving the motor 116 for performing the maintenance process, an encoder sensor 16 for acquiring the moving speed and position information of the carriage 33 in the main scanning direction, and an output signal of the analog sensor 17 are digitally converted. An ADC 116a that converts the value into a value and a sub-scanning encoder sensor (not shown) for acquiring rotational speed and position information of the transport belt 51 in the sub-scanning direction are provided. The control unit 100 is connected to an operation / display panel 117 for inputting and displaying information necessary for the apparatus.

  Here, the control unit 100 transmits a print job including image data from the host 90 side such as a data processing device such as a personal computer, an image reading device such as an image scanner, and an imaging device such as a digital camera via a cable or a network. And received by the host I / F 106. Then, the CPU 101 reads and analyzes the print data in the reception buffer included in the host I / F 106, performs data rearrangement processing by the ASIC 105, transfers the data to the drive waveform generation unit 107, and the drive waveform generation unit 107. The image data and the drive waveform are output to the head driver 108 at a required timing (for example, by an encoder timing signal based on an encoder signal of the encoder sensor 16 or the like). The generation of dot pattern data for image output may be performed, for example, by storing font data in the ROM 102, or the image data is developed into bitmap data by the printer driver 91 on the host 90 side and stored in this apparatus. You may make it forward.

  The drive waveform generation unit 107 includes a D / A converter and an amplifier that perform D / A conversion on drive pulse pattern data stored in the ROM 102 and read out by the CPU 101, and includes a single drive pulse or a plurality of drive pulses. The drive waveform is output to the head driver 108.

The head driver 108 selectively records drive pulses constituting a drive waveform supplied from the drive waveform generator 107 based on image data (dot pattern data) corresponding to one line of the recording head 34 input serially. By applying the pressure to the pressure generating means of the head 34, the ink ejection timing from the recording head 34 is controlled. The head driver 108 shifts the level of the output value of the shift register that receives, for example, a shift register that receives clock data and serial data that is image data, a latch circuit that latches the register value of the shift register using a latch signal, A level conversion circuit (level shifter) and an analog switch array (switch means) whose on / off is controlled by this level shifter, etc., and the required drive pulse included in the drive waveform by controlling the on / off of the analog switch array Is selectively applied to the pressure generating means of the recording head 34 to drive the recording head 34.
Up to this point, the configuration is the same as that of a conventional inkjet recording apparatus.

  By the way, in the ink jet recording apparatus, the carriage 33 is moved in the main scanning direction (x direction) along the guide rod (sliding shaft) 31 by the main scanning motor driving unit 111 and the main scanning motor 110 in accordance with a command from the CPU 101 as described above. ). At this time, since the bearing portion of the carriage 33 and the guide rod 31 are in contact with each other, the bearing portion which is a contact portion with the guide rod 31 of the carriage 33 due to sliding (friction) or the like after repeated use (aging), or As a result, the guide rod 31 itself is worn down and scraped off, and as a result, the clearance (gap) between the bearing portion of the carriage 33 and the guide rod 31 increases, or irregularities on the bearing portion of the carriage 33 and the surface of the guide rod 31 occur. Occurred (this is called deterioration with time of the main scanning sliding part), and the carriage 33 tilted when the carriage 33 reciprocated in the main scanning direction.

There are three types of inclinations of the carriage 33 that occur due to the deterioration of the main scanning sliding parts with time.
5 to 7 show the inclinations (1), (2), and (3) of the carriage 33 caused by the deterioration of the main-scanning sliding component with time.

  FIG. 5 is a view of the inclination (1) of the carriage 33 as viewed from the front of the carriage 33. The inclination of the carriage 33 in the x-axis (main scanning direction, left-right direction in the figure) -z-axis (device height direction, up-down direction in the figure) plane is shown. The carriage 33 is the origin of the xz plane (inside the carriage 33). The guide rod 31 is inclined so as to rotate around a certain point). In FIG. 5, the recording head 34 is similarly inclined by the inclination of the carriage 33, and the ejection line of the ejected ink is inclined with respect to the z-axis, so that it is mounted on the carriage 33 that has no inclination. A recording image whose position is shifted in the main scanning direction with respect to the position of the recording image (initial recording image) formed on the sheet by ejecting ink directly below the recording head 34 (parallel to the z-axis). .

  FIG. 6 is a view of the inclination (2) of the carriage 33 as viewed from above the carriage 33. The inclination of the carriage 33 in the x-axis (main scanning direction, horizontal direction in the figure) -y-axis (sub-scanning direction, vertical direction in the figure) plane is shown. The carriage 33 is the origin of the xy plane (inside the carriage 33). The guide rod 31 is inclined so as to rotate about a certain point). In FIG. 6, the recording head 34 is similarly inclined by the inclination of the carriage 33, and the ejection line of the ejected ink is inclined with respect to the y-axis, so that it is mounted on the carriage 33 that has no inclination. Rotating and moving around the origin on the xy plane with respect to the position of the recorded image (initial recorded image) formed on the sheet by ejecting ink directly below the recording head 34 (parallel to the y-axis) Thus, the recorded image is shifted in position.

  FIG. 7 is a view of the inclination (3) of the carriage 33 as viewed from the side surface of the carriage 33. The inclination of the carriage 33 in the y-axis (sub-scanning direction, left-right direction in the figure) -z-axis (device height direction, up-down direction in the figure) plane is shown. The carriage 33 is the origin of the yz plane (guide rod 31). ) To tilt around. In FIG. 7, the recording head 34 is similarly inclined due to the inclination of the carriage 33, and the ejection line of the ejected ink is also inclined with respect to the z axis, so that the carriage 33 is originally mounted on the carriage 33 with no inclination. A recording image whose position is shifted in the sub-scanning direction with respect to the position of the recording image (initial recording image) formed on the sheet by ejecting ink directly below the recording head 34 (parallel to the z-axis). .

  As described above, as the three types of carriages 33 are tilted, the recording head 34 also has three types of tilts, which causes a problem that the position of the recorded image is shifted due to the respective tilt components.

The present invention solves this problem. That is, the image forming apparatus (inkjet recording apparatus) according to the present invention includes a carriage (carriage 33) on which a recording head (recording head 34) for forming an image on a recording medium (paper 42) by discharging ink is mounted. Scanning means (main scanning motor 110, timing belt 202) that scans the carriage in the direction (main scanning direction) perpendicular to the conveyance direction (sub-scanning direction) of the recording medium along the sliding axis (guide rod 31). ), A reference pattern (reference pattern 7) provided in the image forming apparatus main body (apparatus main body 1), and the reference pattern mounted on the carriage when the carriage comes to a predetermined position of the sliding shaft. The imaging means (imaging sensor 37) and the imaging means take an image of the reference pattern at an early stage as a use history of the carriage or the sliding shaft. The obtained reference image is compared with the calibration image obtained by imaging the reference pattern by the imaging means at a predetermined timing as the use history of the carriage or the sliding shaft, and the amount of inclination of the carriage with respect to the sliding shaft is compared. Detecting means (ASIC 105) for detecting (carriage inclination amount) and correcting means (CPU 101) for correcting the driving of the recording head using the carriage inclination amount detected by the detecting means.
Hereafter, the part which comprises the basis of this invention is demonstrated.

8 and 9 are a side view and a top view showing an internal configuration of an ink jet recording apparatus which is an image forming apparatus according to the present invention.
The ink jet recording apparatus is mounted on a carriage 33 with a reference pattern (reference pattern 7) provided in the image forming apparatus main body (apparatus main body 1), and the carriage 33 comes to a predetermined position on the slide shaft (guide rod 31). And an image pickup means (image pickup sensor 37) for picking up the reference pattern. As a result, the reference pattern 7 attached to the upper surface (ceiling inner surface side) of the apparatus main body 1 is read by the image sensor 37, whereby the inclination of the carriage 33 due to deterioration with time of the main-scanning sliding component can be calculated ( Details will be described later). 8 and 9, the imaging sensor 37 is attached to the upper portion of the carriage 33 and the reference pattern 7 is attached to the upper surface of the apparatus main body 1. However, the imaging sensor 37 is fixed to the carriage 33 and accompanying the scanning of the carriage 33. Other locations may be used as long as the same movement operation is performed in the main scanning direction and the reference pattern 7 is at a position where the image sensor 37 can read. For example, as indicated by a dotted line in FIG. 8, the image sensor 37 is mounted on the side surface on the front side of the apparatus of the carriage 33, and the reference pattern 7 is located on the inner side of the apparatus front side surface of the apparatus body 1. You may arrange | position in the position which opposes.

  Here, the imaging sensor 37 is a device that captures an image of a two-dimensional region including the reference pattern 7 at a predetermined position as one image data, and includes, for example, an area sensor (two-dimensional image sensor). Alternatively, it may be a line sensor in which CCD (charge-coupled device) elements are arranged in a line in the sub-scanning direction, and are scanned by a certain distance in the main scanning direction to obtain one image data.

  Further, the image sensor 37 may be mounted on a surface other than the scanning direction side of the outer surface of the carriage 33, but the surface opposite to the surface facing the recording medium (paper 42) or other than the scanning direction side. It is preferable to be mounted on the side surface of this. Furthermore, it is preferable that the image sensor 37 is disposed at a position farthest from the bearing portion of the sliding shaft (guide rod 31) on the mounting surface of the carriage 33. As a result, the inclination of the carriage 33 can be detected with high sensitivity.

  The reference pattern 7 is preferably provided at a predetermined position in the apparatus main body 1 along the scanning direction (main scanning direction) of the carriage 33, which is a position facing the image sensor 37. Further, the reference pattern 7 may be composed of a plurality of linear marks extending at least one each in two orthogonal directions (for example, the main scanning direction and the sub-scanning direction).

FIG. 10 is a pattern example of the reference pattern 7. FIG. 10A shows the reference pattern 7, and FIG. 10B shows the carriage 33 and the image sensor 37 corresponding to the reference pattern 7.
Here, the reference pattern 7 extends in the main scanning direction (x direction) and is orthogonal to the two linear marks Lx1, Lx2 and the marks Lx1, Lx2 that are parallel to each other (y direction), and is provided at regular intervals. In addition, a lattice pattern composed of n linear marks Ly1, Ly2,. In this case, the imaging sensor 37 basically captures an image as one image data including the two marks Lx1 and Lx2 and the two marks Lyn-1 and Lyn. Although it is possible to detect the inclination of the carriage 33 with each of the mark Lx1 and the mark Lyn, if the inclination of the rotation direction of the carriage 33 with respect to the guide rod 31 is large, the mark Lx1 falls outside the sensor reading range. In order to prevent this, two in the x and y directions are used. Further, the interval between the marks Lx1 and Lx2 and the interval between the marks Lyn-1 and Lyn is not less than the line interval that can be read by the image sensor 37, and at least 1 in the x and y directions within the reading range read by the image sensor 37. It is good to set it as the space | interval which is contained more than this.

  Although FIG. 10 shows a pattern in which marks are continuous in the main scanning direction, the present invention is not limited to this as long as the reference pattern 7 can be detected at a predetermined position in the main scanning direction. For example, at each predetermined position (at regular intervals in the main scanning direction), two well-shaped marks extending in the main scanning direction and the sub-scanning direction may be provided, and these may be imaged by the imaging sensor 37. .

  Further, the mark constituting the reference pattern 7 may be a printed matter provided directly or indirectly on the inner surface of the apparatus main body 1. However, in the image data obtained by the imaging sensor 37, the boundary between the portion with the mark and the portion without the mark can be identified. If so, it may be a three-dimensional structure (for example, one constituted by unevenness). Further, the color used in the printed material is not particularly limited as long as the pattern can be recognized from the captured image data.

Next, FIG. 11 shows a block diagram of the main part of the control unit in the image forming apparatus of the present invention. The control block diagram shown in FIG. 4 shows the parts related to the configuration of the present invention.
Here, a control signal for the image sensor 37 is sent from the CPU 101, and image data obtained by the image sensor 37 reading the reference pattern 7 is sent to the ASIC 105 that performs image processing.

FIG. 12 is a timing chart of image data reading by the image sensor 37 in the configuration of FIG.
The timing of the control signal from the arithmetic unit (CPU 101) when the imaging sensor 37 attached to the carriage 33 reads the reference pattern 7 is the white area in the transparent portion (FIG. 12A) of the absolute position pattern (encoder scale 16a). ) Is detected by the transmission sensor (encoder sensor 16) attached to the carriage 33 (ON region in FIG. 12B).

  The signal from the encoder sensor 16 is monitored by the arithmetic unit (CPU 101), and the output signal (ON signal) of the encoder sensor 16 is detected by the internal high-speed clock (FIG. 12 (c)). However, the output of the encoder sensor 16 and the arithmetic device internal high-speed clock are asynchronous. For this reason, image reading is started in synchronization with the rise of the internal high speed clock immediately after the encoder sensor 16 is turned ON (the fall of the internal high speed clock may be synchronized).

  The image processing device (ASIC 105) is instructed from the operation device (CPU 101) to the image gate signal (FIG. 12 (d)) and the image data acquisition timing synchronization signal (FIG. 12 (e)) synchronized with the rise of the internal high-speed clock. Thus, the image data from the image sensor 37 is acquired.

  The area from which image data is acquired is the entire area for the entire main scanning area or an area designated by the image gate signal. Further, it is possible to acquire an image at a designated position in main scanning by asserting the image gate signal a plurality of times. The arithmetic unit (CPU 101) also includes a counter, which counts the number of times the output of the encoder sensor 16 is turned on or the number of high-speed clocks inside the arithmetic unit from the output of the encoder sensor 16 being counted. It is possible to acquire an image in an arbitrary area. Here, the detection of the transmitting part of the encoder scale 16a is used as a reference, but the blocking part (the black region in FIG. 12A) may be used as a reference.

  In the present invention, first, the imaging sensor 37 captures the reference pattern 7 at a predetermined position in the main scanning direction to obtain a reference image at the initial stage as the use history of the carriage 33 or the guide rod 31, and the reference image data is stored in the NVRAM 104. Save to. The stored reference image data can be read out by a command from the CPU 101. Next, the imaging sensor 37 captures the reference pattern 7 at the predetermined position at a predetermined timing as the use history of the carriage 33 or the guide rod 31 to obtain a calibration image, and compares the calibration image with the reference image. Thus, the amount of inclination of the carriage 33 with respect to the guide rod 31 (carriage inclination amount) is detected. Thereby, it is possible to detect the above-described three kinds of inclinations (FIGS. 5 to 7) of the carriage 33.

That is, the inclination (1) of the carriage 33 shown in FIG. 5 is detected as a positional deviation d1 in the main scanning direction in the reference pattern 7.
Further, the inclination (2) of the carriage 33 shown in FIG. 6 is detected as a positional deviation due to rotation in the reference pattern 7.
Further, the inclination (3) of the carriage 33 shown in FIG. 7 is detected as a positional deviation d2 in the sub-scanning direction in the reference pattern 7.

These positional deviation relationships are established in the case of the arrangement relationship between the image sensor 37 and the reference pattern 7 shown in FIGS. Although the positional deviation relationship in the reference pattern 7 changes depending on the arrangement relationship between the imaging sensor 37 and the reference pattern 7, in any case, the detection can be detected separately in the three types of inclinations of the carriage 33 in FIGS. .
Hereinafter, detection and calculation methods for the inclinations (1), (2), and (3) of the carriage 33 will be described.

[Calculation of Inclination (1) of Carriage 33]
FIG. 13 is a reference image obtained by reading the reference pattern 7 at a predetermined position with the image sensor 37 when the carriage 33 is in the initial state. The reference image is an image in which a well (lattice pattern) made up of marks Lx1, Lx2 and marks Ly1, Ly2 is at the center of the screen. The reference image for detecting the inclination of the carriage 33 is not particularly required to be at the center as shown in FIG. 13, but here, for the sake of simplicity, the lattice is assumed to be at the center of the screen.

FIG. 14 is a calibration image obtained by reading the reference pattern 7 at a predetermined position with the image sensor 37 when the carriage 33 is tilted in the xz plane due to deterioration with time of the main scanning sliding component. The reference image of FIG. 13 is shown with a dotted line.
If the image is acquired by the image sensor 37 at the same timing as that of the reference image, the carriage 33 is inclined (see FIG. 5). Therefore, the image sensor 37 itself is also inclined, and the carriage 33 is lowered to the left in FIG. Thus, the marks Ly1 ′ and Ly2 ′ that are vertical lines on the calibration image are shifted to the right in the drawing from the marks Ly1 and Ly2 in the initial state. On the other hand, when the carriage 33 is in the right-down state in FIG. 5 as opposed to FIG. 5, the vertical line marks Ly1 ′ and Ly2 ′ are shifted to the left in the drawing from the initial state. .

Here, the inclination angle θxz of the inclination (1) of the carriage 33 at this time can be calculated as follows.
That is, when the reference image and the calibration image data are binarized by image processing of the image data in the ASIC 105 and viewed only in the main scanning direction (x direction), an initial image (reference image) as shown in FIG. The difference between the position of the vertical lines (marks Ly1, Ly2) and the position of the vertical lines (marks Ly1 ′, Ly2 ′) in the calibration image after deterioration with time of the main scanning sliding part can be detected as a positional deviation amount: d1. It is. At this time, since the distance L between the image sensor 37 and the reference pattern 7 is determined, the inclination angle θxz can be calculated by the following equation (1).

      tan θxz = d1 / L (1)

[Calculation of Inclination (2) of Carriage 33]
FIG. 15 is a calibration image obtained by reading the reference pattern 7 at a predetermined position with the image sensor 37 when the carriage 33 is tilted in the xy plane due to the deterioration of the main scanning sliding part over time. The reference image of FIG. 13 is shown with a dotted line.
Even when the carriage 33 is tilted on the xy plane, the reference image of the reference pattern 7 in the initial state and the main-scanning sliding part after deterioration with time are calculated in the same manner as the calculation of the tilt (1) of the carriage 33 (tilt on the xz plane). The calibration images of the reference pattern 7 are compared, and the inclination is calculated. Note that both the reference image and the calibration image at this time are displayed as the same image in the screen scanning size of the length a of the screen in the main scanning direction (screen width) and the length b of the screen in the sub-scanning direction (screen height). .

  First, when an image is acquired by the imaging sensor 37 at the same timing as that of the reference image, the imaging sensor 37 itself is tilted because it is in a left-down state with respect to the xy plane in FIG. In this state, as shown in FIG. 15, the lattice pattern is read in a state of being tilted to the right side (right rotation). On the other hand, when the carriage 33 is in the right-down state in FIG. 6, the lattice pattern is read in a state of being tilted to the left (left-rotation) in the drawing.

Here, the inclination angle θxy of the inclination (2) of the carriage 33 at this time can be calculated as follows.
That is, the reference image and the calibration image data are binarized by the image processing of the image data in the ASIC 105, and the coordinates at the image end portion of the lattice pattern are represented as shown in FIG. In FIG. 15A, the coordinates of the black circle plots on the four sides of the screen are referred to. For example, the coordinates of both ends of the mark Lx1 of the reference image are (x1, y1), (x2, y2), and the mark Lx2 The coordinates of both ends are (x3, y3) and (x4, y4). Further, the coordinates of both ends of the calibration image mark Lx1 ″ are (x1 ′, y1 ′) and (x2 ′, y2 ′), and the coordinates of both ends of the mark Lx2 ″ are (x3 ′, y3 ′) and (x4 ′). , Y4 ′). Also, the coordinates of both ends of the mark Ly1 ″ are (x5 ′, y5 ′) and (x7 ′, y7 ′), and the coordinates of both ends of the mark Ly2 ″ are (x6 ′, y6 ′) and (x8 ′, y8 ′). It is.

  Since the inclination (2) of the carriage 33 is the position of θxy shown in FIG. 15B, it can be calculated from the screen length a in the main scanning direction and the positional deviation amount of the marks Lx1 ″ and Lx2 ″ which are horizontal lines. Here, the screen length a of the read image is known because the image data range is set by a control signal from the arithmetic unit (CPU 101), and the positional deviation amount of the marks Lx1 ″ and Lx2 ″ from the marks Lx1 and Lx2 Is obtained as | y1′−y1 | + | y2′−y2 | from the coordinates of the end points of the lattice pattern. Therefore, the inclination angle θxy of the inclination (2) of the carriage 33 can be calculated by the following expression (2).

      tan θxy = (| y1′−y1 | + | y2′−y2 |) / a (2)

[Calculation of Inclination (3) of Carriage 33]
FIG. 16 is a calibration image obtained by reading the reference pattern 7 at a predetermined position with the image sensor 37 when the carriage 33 is inclined in the yz plane due to deterioration with time of the main scanning sliding component. The reference image of FIG. 13 is shown with a dotted line.
When the carriage 33 is tilted with respect to the yz plane, the reference image of the reference pattern 7 in the initial state and the main-scanning sliding component after deterioration with time are calculated in the same manner as the calculation of the tilt (1) of the carriage 33 (tilt on the xz plane). The calibration images of the reference pattern 7 are compared, and the inclination is calculated.

  If the image is acquired at the same timing as the reference image by the image sensor 37, the carriage 33 is tilted (see FIG. 7). Therefore, the image sensor 37 itself is also tilted, and the carriage 33 is lowered to the left in FIG. Therefore, the mark Lx1 ′, Lx2 ′ which is a horizontal line on the calibration image is more than the marks Lx1, Lx2 in the initial state because the position shifted in one direction in the sub-scanning direction (leftward in FIG. 7) from the initial state is read. Will also shift downward in FIG. On the other hand, when the carriage 33 is in the right-down state in FIG. 7 as opposed to FIG. 7, it is shifted in the reverse direction of the sub-scanning direction, so that the horizontal line marks Lx1 ′ and Lx2 ′ are initial. It will shift | deviate to the upper direction of FIG. 16 rather than a state.

Here, the inclination angle θyz of the inclination (3) of the carriage 33 at this time can be calculated as follows.
That is, when the reference image and the calibration image data are binarized by image processing of the image data in the ASIC 105 and viewed only in the y direction, the horizontal line (mark Lx1) of the initial image (reference image) as shown in FIG. , Lx2) and the position of the horizontal lines (marks Lx1 ′, Lx2 ′) in the calibration image after deterioration with time of the main-scanning sliding component can be detected as a positional deviation amount: d2. At this time, since the distance L between the image sensor 37 and the reference pattern 7 is determined, the inclination angle θyz can be calculated by the following equation (3).

      tan θyz = d2 / L (3)

[Calculation of the inclination in which the inclinations (1), (2) and (3) of the carriage 33 are combined]
FIG. 17 is obtained by reading the reference pattern 7 at a predetermined position with the image sensor 37 when the inclinations (1), (2), and (3) of the carriage 33 are combined due to deterioration with time of the main scanning sliding parts. Calibration image. The reference image of FIG. 13 is shown with a dotted line. Note that both the reference image and the calibration image at this time are displayed as the same image in the screen scanning size of the length a of the screen in the main scanning direction (screen width) and the length b of the screen in the sub-scanning direction (screen height). .

The inclination calculation when the inclinations (1), (2), and (3) of the carriage 33 are combined is performed according to the following procedure.
(S1) First, it is determined whether the inclination of the carriage 33 is combined.
First, binarization of the reference image and the calibration image data is performed by image processing of the image data in the ASIC 105, and the coordinates at the image end of the lattice pattern are represented as shown in FIG. Do. In FIG. 17, the coordinates of the black circle plots on the four sides of the screen are shown. For example, the coordinates of both ends of the mark Lx1 of the reference image are (x1, y1) and (x2, y2), and both ends of the mark Lx2. Are coordinates (x3, y3) and (x4, y4). The coordinates of both ends of the mark Ly1 are (x5, y5) and (x7, y7), and the coordinates of both ends of the mark Ly2 are (x6, y6) and (x8, y8). Further, the coordinates of both ends of the calibration image mark Lx1 ″ ′ are (x1 ″ ′, y1 ″ ′) and (x2 ″ ′, y2 ″ ′), and the coordinates of both ends of the mark Lx2 ″ ′ are (x3 ″ ′, y3 ″ ′) and (x4 ″ ′, y4 ″ ′). Further, the coordinates of both ends of the mark Ly1 ″ ′ are (x5 ″ ′, y5 ″ ′) and (x7 ″ ′, y7 ″ ′), and the coordinates of both ends of the mark Ly2 ″ ′ are (x6 ″ ′, y6 ″ ′). , (X8 ″ ′, y8 ″ ′).

(Decision 1) | y1-y1 "'| = | y2-y2"' | and | x5-x5 "'| = | x7-X7"' | In this case, between the reference image and the calibration image The absolute value of the difference between the coordinate positions of the horizontal and vertical lines is the same on the left and right and top and bottom of the screen. That is, it is determined that only the inclination of the xy plane (inclination (2) of the carriage 33) is generated with respect to the initial state due to the deterioration with time of the main scanning sliding component. Therefore, it is only necessary to detect the inclination of the xy plane: the inclination of θxy.

(Decision 2) | y1-y1 "'| = | y2-y2"' | and | x5-x5 "'| ≠ | x7-X7"' | In this case, between the reference image and the calibration image The absolute value of the difference between the coordinate positions of the horizontal lines on the left and right of the screen is the same as in the case of (Judgment 1), but the absolute value of the difference between the coordinate positions of the vertical lines on the upper and lower sides is the same. It is not in a state. That is, it is determined that there is an inclination between the inclination of the xy plane: θxy and the inclination of the xz plane: θxz (the inclinations (1) and (2) of the carriage 33).

(Determination 3) | y1-y1 "'| ≠ | y2-y2"' | and | x5-x5 "'| = | x7-X7"' | In this case, the case of (determination 2) is Conversely, the absolute value of the difference in coordinate position between the upper and lower screens of the vertical line matches, but the absolute value of the difference in coordinate position between the left and right screens of the horizontal line does not match. That is, it is determined that there is an inclination of the inclination of the xy plane: θxy and the inclination of the yz plane: the inclination of θyz (the inclinations (2) and (3) of the carriage 33).

(Decision 4) | y1-y1 "'| ≠ | y2-y2"' | and | x5-x5 "'| ≠ | x7-X7"' | In this case, the horizontal line on the left and right of the screen and the vertical line The absolute value of the difference between the coordinate positions of the end points at the top and bottom of the screen is not the same. That is, it is determined that there is an inclination of xy plane inclination: θxy, xz plane inclination: θxz, and yz plane inclination: θyz (carriage 33 inclination (1), (2), (3)).

  In the above, the determination is made based on whether or not the absolute position difference between the coordinate positions of the end points on the horizontal and vertical lines on the left and right sides of the screen is the same or not, but it is determined by setting a certain range in the screen. It is also possible to perform.

In the case of the above (determination 2) to (determination 4), when it is determined that the inclinations are combined, the inclination of the carriage 33 is calculated as follows.
(S2) Since all of (determination 2) to (determination 4) have the inclination of the xy plane, θxy is first calculated. This calculation method may be the same as the calculation method of the inclination (2) of the carriage 33 (the inclination of the xy plane), and can be calculated by the following equation (4).

      tan θxy = (| y1 ″ ′ − y1 | + | y2 ″ ′ − y2 |) / a (4)

(S3) The image is rotated for the calibration image data by the image processing in the ASIC 105. At this time, the rotation center is the center of the calibration image data, the rotation angle is the angle θxy calculated in step S2, and the rotation is rotated in a direction to cancel the inclination (2) of the carriage 33 in the calibration image.

(S4) Since the image processing in step S3 has only the inclination of the xz plane and the yz plane (the inclinations (1) and (3) of the carriage 33) as shown in FIG. 18, the inclination of the carriage 33 described above. (1) The respective inclinations are calculated by the following equations (5) and (6) in the same manner as the calculation method of (tilt of xz plane) and the calculation method of inclination of carriage 33 (3) (tilt of yz plane). .

tan θxz = d1 / L (5)
tan θyz = d2 / L (6)

FIG. 19 shows a flowchart of processing relating to the inclination correction of the carriage 33 in the image forming apparatus according to the present invention.
[Reference image acquisition step]
In a state where the sliding parts of the guide rod 31 and the carriage 33 are not worn away at the time of shipment or the like, the image data (reference image) of the reference pattern 7 is acquired as the initial state data by the imaging sensor 37. Specifically, the following procedure is performed. At this time, the tilt detection function of the carriage 33 is turned off and steps S11 to S13 are executed.
(S11) The CPU 101 scans the carriage 33 in the main scanning direction under the control of the main scanning motor 110 and the main scanning motor driving unit 111 which are main scanning drivers.
(S12) After the encoder sensor 16 detects the transmission part of the encoder scale 16a, the reference pattern 7 is captured by the imaging sensor 37 at a predetermined position in the main scanning direction of the carriage 33 to obtain a reference image.
(S13) The reference image data obtained in step S12 is stored in the NVRAM 104 in a state where it can be called by a command from the CPU 101.

[Slope calculation step]
In the image forming apparatus (inkjet recording apparatus), the inclination detection function of the carriage 33 is turned on at a predetermined timing, the inclination of the carriage 33 is calculated, and the ink ejection timing correction value is calculated, and the process ends. Specifically, the following procedure is performed.
(S21) The CPU 101 scans the carriage 33 in the main scanning direction under the control of the main scanning motor 110 and the main scanning motor driving unit 111 which are main scanning drivers.
(S22) After the encoder sensor 16 detects the transmission part of the encoder scale 16a, the image sensor 37 captures the reference pattern 7 at the same predetermined position as when the reference image in the main scanning direction of the carriage 33 is acquired, and a calibration image. To get.
(S23) The calibration image data obtained in step S12 is stored in the NVRAM 104 in a state where it can be called by a command from the CPU 101.
(S24) Since the tilt detection function of the carriage 33 is ON (Yes in S14), the process proceeds to the next step.
(S25) The reference image data and the calibration image data at the same position in the main scanning direction stored in the NVRAM 195 are called, and the inclination of the carriage 33 is calculated. Specifically, since there is a possibility that the inclinations (1), (2), and (3) of the carriage 33 are inclined in combination, the inclination of the carriage 33 is calculated according to the procedure of steps S1 to S4.
(S26) If it is determined in step S25 that the carriage 33 is not tilted (No in S26), the process ends. If the carriage 33 is inclined, the process proceeds to the next step S27.
(S27) Based on the calculation result of step S26, a correction value for correcting the drive of the recording head 34 is calculated. Here, the correction of the driving of the recording head 34 is to correct the ejection timing of ink from the nozzles. Alternatively, the position of the nozzle to be driven and / or the ejection timing of the nozzle in the nozzle row of the recording head 34 may be corrected.

[Image formation preparation step]
FIG. 20 is a flowchart relating to image formation (printing) availability determination in the image formation preparation step.
(S31) Here, first, ON / OFF selection of whether or not to use the inclination correction function of the carriage 33 is performed before image formation. If the correction function is ON, the process proceeds to the next step S32, and if the correction function is OFF, the step is performed with the condition setting that does not reflect the correction value for the position of the nozzle to be driven and / or the discharge timing of the nozzle in the nozzle row of the recording head 34. Proceed to S33.
(S32) Using the correction value calculated in step S27, the position of the nozzle to be driven and / or the discharge timing of the nozzle in the nozzle row of the recording head 34 is reset.
(S33) A determination is made as to whether or not image formation is possible based on the position of the nozzles to be driven in the nozzle row of the recording head 34 and / or the conditions of the ejection timing of the nozzles. If image formation is not possible (No in S33), the process returns to step S31. If image formation is possible (Yes in S33), the process proceeds to an image formation step (END).

  In the image forming step, when the tilt correction function is ON, the correction value in S27 is reflected in the drive of the recording head 34, and image formation based on the input image data is performed. As a result, the positional deviation of the recorded image (decrease in ink ejection accuracy) due to the inclination of the carriage 33 caused by the deterioration with time of the main-scanning sliding component (shaving of the bearing portion of the carriage 33 or the guide rod 31) is suppressed, and the initial Good image formation similar to the state can be performed.

  The above series of processing may be performed at an arbitrary timing. For example, the reference image is acquired when the apparatus is shipped, when the image forming apparatus is installed, or when the carriage 33 or the guide rod 31 is replaced. The acquisition of the calibration image and the calculation of the inclination of the carriage 33 are performed when the power of the image forming apparatus is turned on, during maintenance of the image forming apparatus, or when an image is formed on a certain number of sheets. Further, this series of processing is preferably applied to scanning in each of the main scanning two directions (left and right directions in FIG. 5) of the carriage 33. In this case, the scanning direction of the carriage 33 is the same in each of the reference image acquisition step, the inclination calculation step, and the image formation preparation step.

  Although the present invention has been described with the embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and other embodiments, additions, modifications, deletions, etc. Can be changed within the range that can be conceived, and any embodiment is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited.

FIG. 3 is a perspective explanatory view seen from the front side of the ink jet recording apparatus as the image forming apparatus according to the present invention. It is a side schematic block diagram explaining the whole structure of the mechanism part of the apparatus. It is principal part plane explanatory drawing of the mechanism part. 2 is a block diagram of the entire control unit of the image forming apparatus of the present invention. FIG. It is the schematic which shows the state of the inclination (1) of a carriage. It is the schematic which shows the state of the inclination (2) of a carriage. It is the schematic which shows the state of the inclination (3) of a carriage. It is a side view which shows the arrangement state of the imaging sensor and reference | standard pattern in the inkjet recording device of FIG. FIG. 2 is a top view showing an arrangement state of imaging sensors and reference patterns in the ink jet recording apparatus of FIG. 1. It is the schematic which shows the example of a pattern of a reference | standard pattern. FIG. 3 is a main block diagram of a control unit in the image forming apparatus of the present invention. 12 is a timing chart of image data reading by the imaging sensor in the configuration of FIG. It is a figure which shows the example of the reference | standard image obtained by reading a reference | standard pattern with an image sensor when a carriage is an initial state. It is a figure which shows the example of the calibration image obtained by reading a reference | standard pattern with an imaging sensor, when a carriage inclines in xz plane by deterioration with time of main scanning sliding components. It is a figure which shows the example of the calibration image obtained by reading a reference | standard pattern with an image sensor, when a carriage inclines in xy plane by deterioration with time of main scanning sliding components. It is a figure which shows the example of the calibration image obtained by reading a reference | standard pattern with an imaging sensor, when a carriage inclines in yz plane by deterioration with time of main scanning sliding components. It is a figure which shows the example of the calibration image obtained by reading a reference | standard pattern with an image sensor when the inclination (1), (2), (3) of a carriage is compounding. It is a figure which shows the example of the calibration image after performing the image process which negates the inclination (2) of a carriage about the calibration image of FIG. 6 is a flowchart of processing relating to carriage tilt correction in the image forming apparatus according to the present invention. 6 is a flowchart relating to image formation (printing) availability determination in an image formation preparation step.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Paper feed tray 3 Paper discharge tray 4 Cartridge loading part 5 Operation / display part 7 Reference pattern 10, 10k, 10c, 10m, 10y Ink cartridge 11k, 11c, 11m, 11y Remaining amount display part 12 Power button 13 Paper feed / Print resume button 14 Cancel button 16 Encoder sensor (transmission type sensor)
16a Encoder scale (absolute position pattern)
17 Sensor (Analog sensor)
21 Frame 24 Supply pump 30 Control unit 31, 39 Guide rod 32 Stay 33 Carriage 34 Recording head 35 Sub tank 36 Ink supply tube 37 Imaging sensor 42 Paper (recording medium)
51 Conveying belt 81 Maintenance / recovery mechanism 82, 82a, 82b, 82c, 82d Cap 83 Wiper blade 84, 88 Empty discharge receptacle 89 Opening 90 Host PC
100 control unit 101 CPU
102 ROM
103 RAM
104 NVRAM
105 ASIC
106 Host I / F
107 driving waveform generation unit 108 head driver 110 main scanning motor 111 main scanning motor driving unit 112 sub scanning motor 113 sub scanning motor driving unit 114 AC bias supply unit 115 maintenance recovery mechanism driving unit 116 motor 116a ADC
117 Operation / Display Unit Lx1, Lx2, Lx1 ′, Lx2 ′, Lx1 ″, Lx2 ″, Lx1 ″ ′, Lx2 ″ ′, Ly1, Ly2, Ly1 ′, Ly2 ′, Ly1 ″, Ly2 ″, Ly1 ″ ′, Ly2 "', Lyn mark

Claims (9)

A carriage that mounts a recording head that discharges ink to form an image on a recording medium;
In the image forming apparatus having a scanning means for scanning in the direction orthogonal to the carriage along a sliding axis in the conveying Direction of the recording medium,
Position information acquisition means for acquiring position information of the carriage on the basis of the first pattern provided on the image forming instrumentation 置内,
An imaging unit mounted on the carriage for imaging a second pattern provided in the image forming apparatus when the carriage reaches a predetermined position acquired by the position information acquisition unit ;
A reference image obtained by imaging the second pattern in advance at the predetermined position by the imaging unit is compared with a calibration image obtained by imaging the second pattern by the imaging unit at the predetermined position. And detecting means for detecting the amount of inclination of the carriage relative to the sliding axis ,
An image forming apparatus , wherein an image is formed based on an inclination amount of the carriage with respect to a sliding axis and position information of the carriage . The image forming apparatus according to claim 1, wherein the first pattern is a pattern recorded at equal intervals that is read by a sensor provided on the carriage. The image forming apparatus according to claim 1, wherein the reference image is an image obtained by photographing the second pattern by the imaging unit in an initial stage of use of the carriage. The second pattern, the image forming apparatus according to claim 1 which is provided at a position opposed to the image pickup means to the 3. 5. The image forming apparatus according to claim 1, wherein the second pattern includes a plurality of linear marks extending at least one in each of two orthogonal directions. 6. It said imaging means, an image forming apparatus according to claim 1 which is disposed at the farthest position from the bearing portion of the sliding shaft in key Yarijji outer surface to 5. The image forming apparatus according to claim 1, wherein the imaging unit is an area sensor or a line sensor. The detection unit compares the calibration image with a reference image, determines a type of inclination with respect to the sliding axis of the carriage, and calculates a carriage inclination amount for each type of inclination . The image forming apparatus according to any one of the above. Before SL using carriage inclination amount, the image forming apparatus according to claim 1 for forming an image by correcting the ejection timing of ink from the recording head to 8.

Images