JP2009233962A - Inspection method for inkjet printer and determination chart - Google Patents

Abstract

An inkjet printer inspection method capable of detecting an inclination generated around an axis along a main scanning direction or a sub-scanning direction with respect to a recording medium on a discharge nozzle surface itself.
A first ink droplet is landed on a recording medium from a predetermined ink nozzle while moving in a forward path direction at a point in a main scanning direction X, and a second ink is transferred from the predetermined ink nozzle while moving at the same point in a backward direction. A step of creating a determination chart JC by landing ink droplets, an interval determination step of determining landing intervals along the main scanning direction X of the first and second ink droplets landed on the determination chart JC, and an interval determination step And an inclination determination step for determining an inclination state of the discharge nozzle surface 11a with respect to the recording medium P supported by the guide means on the basis of the landing intervals C1a, C2a, C2a, and C2h determined by (1).
[Selection] Figure 13

Description

  The present invention relates to a method for inspecting an ink jet printer comprising a print head having a discharge nozzle surface composed of a large number of ink nozzles and supported so as to be capable of reciprocating along a main scanning direction with respect to a recording medium supported by guide means. And a determination chart created by the inspection method.

  As prior art document information related to this type of ink jet printer inspection method, there is Patent Document 1 shown below. In the ink jet printer inspection method described in Patent Document 1, in a print head having a plurality of discharge nozzle surfaces (head units), a rectangular unit extending in the sub-scanning direction using the first discharge nozzle surfaces. By arranging the pattern in the main scanning direction with a blank portion having a constant width therebetween, a reference pitch pattern having a comb-like shape as a whole is formed on the printed paper, and then using the second discharge nozzle surface A change pitch pattern in which the width of the blank portion provided therebetween changes at a constant rate along the main scanning direction is formed so as to overlap with the reference pitch pattern, but is overlapped 2 By determining the inclination of the light and dark stripes in one pitch pattern with a reflective sensor or the like, the relative inclination state between the first and second ejection nozzle surfaces (recording medium) Slope) of a vertical Z axis in the plane of the can be determined.

JP 2006-15692 A (paragraph numbers 0055-0061, FIGS. 7 and 8)

  However, the inspection method described in Patent Document 1 does not provide a means for detecting the state of each discharge nozzle surface itself when the discharge nozzle surface itself is inclined with respect to the recording medium (print paper). It was.

  Further, the inspection method described in Patent Document 1 is intended for tilting around the Z axis perpendicular to the surface of the recording medium between the ejection nozzle surfaces, but on the other hand, it occurs around the X axis along the main scanning direction. There is no provision for detecting a tilt that is in the plane of the recording medium or a tilt that occurs around the Y axis perpendicular to the main scanning direction. Such an inclination generated around the X axis or the Y axis means that the distance to the recording medium is different between the nozzles, which may affect the quality in high-resolution image formation.

  In view of the above, an object of the present invention is to provide an inclination generated around the X axis along the main scanning direction with respect to the recording medium (print paper) of the discharge nozzle surface itself, or within the surface of the recording medium and in the main scanning direction. An object of the present invention is to provide an ink jet printer inspection method capable of detecting a tilt occurring around a vertical Y axis.

A first characteristic configuration of the present invention is a print head having a discharge nozzle surface composed of a large number of ink nozzles and supported so as to be reciprocally movable along a main scanning direction with respect to a recording medium supported by guide means. An inkjet printer inspection method comprising:
While moving a certain point in the main scanning direction in the forward direction, the first ink droplet is landed from the predetermined ink nozzle on the ejection nozzle surface toward the recording medium, and the predetermined ink nozzle is moved in the vicinity of the same point in the backward direction. A chart creation step for creating a determination chart made of the recording medium by landing the second ink droplets from the recording medium to the recording medium;
An interval determination step for determining a landing interval along the main scanning direction between the first ink droplet and the second ink droplet landed on the determination chart;
And an inclination determination step of determining an inclination state of the discharge nozzle surface with respect to the recording medium supported by the guide means based on the landing interval determined by the interval determination step.

  In the inkjet printer inspection method according to the first characteristic configuration of the present invention, the print head is reciprocated at a constant speed, and the ink droplets ejected from the moving print head are based on the initial speed applied from the print head. From the positional relationship between the first ink droplet landed on the recording medium while moving in the forward direction and the second ink droplet landed on the recording medium while moving in the backward direction using the action of flying obliquely The distance from each discharge nozzle to the recording medium can be determined. That is, as the interval between the ejection nozzle and the recording medium increases, the ink droplets land at a position displaced from the nozzle position at the time of ejection in the main scanning direction, and thus the separation distance between the first ink droplet and the second ink droplet increases. Become. Therefore, an inclination that occurs around the X axis along the main scanning direction with respect to the recording medium of each ejection nozzle surface, or occurs around the Y axis that is in the plane of the recording medium and is perpendicular to the main scanning direction. The inclination can be detected.

According to another characteristic configuration of the present invention, in the chart creating step, at least two ink nozzles separated from each other along the main scanning direction are used as the predetermined ink nozzles.
In the interval determination step, the landing interval indicated by one of the two ink nozzles is compared with the landing interval indicated by the other of the two ink nozzles.

  With this configuration, in the interval determination step, it is possible to determine how the distance from the recording medium differs between at least two ink nozzles that are separated from each other along the main scanning direction. Therefore, in the tilt determination step, based on the comparison, it is possible to determine a tilt component that occurs around the Y axis that is in the plane of the recording medium supported by the guide means and is perpendicular to the main scanning direction. .

According to another characteristic configuration of the present invention, in the chart creation step, at least two ink nozzles separated in a direction perpendicular to the main scanning direction are used as the predetermined ink nozzles.
In the interval determination step, the landing interval indicated by one of the two ink nozzles is compared with the landing interval indicated by the other of the two ink nozzles.

  With this configuration, in the interval determination step, the interval between the at least two ink nozzles separated from each other along the direction perpendicular to the main scanning direction (corresponding to the sub-scanning direction in the configuration in which the recording medium is sub-scanned). It can be determined how the distance from the recording medium differs. Therefore, in the inclination determination step, it is possible to determine an inclination component generated around the X axis along the main scanning direction based on the comparison.

  Another characteristic configuration of the present invention is that, in the chart creating step, a plurality of ink nozzles arranged adjacent to each other in the sub-scanning direction of the print head are used as the predetermined ink nozzles.

  With this configuration, a pattern image that can be easily specified clearly as a line composed of several adjacent dots arranged in the sub-scanning direction can be obtained, so compared with a case where independent ink nozzles that are not adjacent to each other are used as the predetermined ink nozzles. Thus, it is also easy to determine the landing interval in the interval determining step.

  In another aspect of the present invention, the group of the predetermined ink nozzles including the plurality of ink nozzles is set to be adjacent to the next group of the predetermined ink nozzles with a pause ink nozzle not used for ejection interposed therebetween. It is in a certain point.

  In other words, if all the ink nozzles arranged in the sub-scanning direction are set as predetermined ink nozzles, ink droplets simultaneously ejected from adjacent ink nozzles at a short distance from each other have an effect during flight. There is a risk of forming irregular landing points due to mechanical influences. However, in this configuration, a portion obtained by decimating a part from a large number of ink nozzles arranged in the sub-scanning direction becomes a predetermined ink nozzle, and it becomes difficult for the ink droplets to interact during the flight, so that the flight is performed more straight. So the landing points also form a regular pattern. Accordingly, it is easy to determine the landing interval in the interval determination step.

  The determination chart according to the sixth characteristic configuration of the present invention is created by the chart creating step of the inspection method according to any one of claims 1 to 5.

  Using the determination chart according to the present configuration, the first ink droplet landed on the recording medium while moving in the forward direction and the second ink droplet landed on the recording medium while moving in the backward direction are formed on the determination chart. The distance from each discharge nozzle to the recording medium can be determined. Therefore, an inclination that occurs around the X axis along the main scanning direction with respect to the recording medium of each ejection nozzle surface, or occurs around the Y axis that is in the plane of the recording medium and is perpendicular to the main scanning direction. The inclination can be detected.

The best mode for carrying out the present invention will be described below with reference to the drawings.
〔overall structure〕
The ink jet printer shown in FIGS. 1 and 2 prints image information by supplying a print paper P drawn from a roll-shaped print paper RP as a recording medium to a printing unit B by a transport mechanism A. The ink jet printer has a conveying system for discharging to a discharge tray 2 outside the casing 1 through a cutting section C for cutting off a portion of the printed paper P that has been printed, a back printing section D, and a decurling section E for correcting curl. Is provided. In addition, the housing 1 includes a control unit F and an ink storage unit G.

The transport mechanism A includes crimp-type transport rollers 4 and 5 disposed on the upstream side and the downstream side of the printing unit B in the transport direction. The transport mechanism A can also take the cut paper set on the manual feed tray 6 outside the housing 1 by the pressure supply roller 7 and supply it to the printing unit B.
As shown in FIGS. 1 to 5, the printing section B is a paper guide 12 in the form of a suction unit disposed at a position facing the print head H that reciprocates in the main scanning direction X and the transport path of the print paper P. And.

The print head H includes a carriage 10 and an ink discharge unit 11 that is connected to the carriage 10 and discharges ink onto the print paper P to print information, and has a carriage cover 16 that covers the carriage 10. Yes. The suction unit-like paper guide 12 incorporates an electric fan (not shown) that sucks air from a large number of openings formed on the upper surface of the case-like unit and sends it out downward.
The cutting unit C includes a transport roller 21 that transports the printed paper P in a pressure-bonded state, a disk-shaped cutter 22 that cuts the printed paper P, and an operating mechanism 23 that reciprocates the disk-shaped cutter in the main scanning direction X. ing.

The back print unit D includes a print head 24 that prints information on the back side of the print paper P. In order to correct the curl of the print paper P, the decurling unit E is configured to convey the print paper P by curving it in the direction opposite to the winding direction of the roll-shaped print paper RP. One correction roller 26 disposed at a position facing the roller 25 and a plurality of guide plates 27 are provided. Although not shown in the drawing, the decurling unit E includes an electric motor that drives the conveyance roller 25, and corrects curl when the print paper P is pressed and conveyed by the conveyance roller 25 and the correction roller 26.
A plurality of ink cartridges (not shown) are set in the ink reservoir G, and ink sent from the ink reservoir G is supplied from an intermediate tank (not shown) to the print head H via a tube.

[Print processing form]
When printing, the transport mechanism A feeds the leading end of the print paper P to the lower position of the print unit B and stops. In this state, a negative pressure from the suction unit-like paper guide 12 is applied to the back side of the print paper P, so that the print paper P is attracted to the upper surface of the paper guide 12 and maintained in a smooth state. In such a state, while the print head H is reciprocated in the main scanning direction (X-axis direction), ink is ejected from the ink ejection unit 11 to the print paper P to print image information and the like.

  More specifically, printing is performed by ejecting ink from the ink ejection unit 11 while moving the print head H in the main scanning direction X from the home position HP toward the turning point TP. When the print head H reaches the turning point TP, the transport mechanism A transports the print paper P by a predetermined amount in the sub-scanning direction (Y-axis direction). After this conveyance, the print head H is moved to the other side in the main scanning direction (from the turning point TP to the home position HP), and information is printed on the print paper P while ejecting ink from the ink ejection unit 11. .

  When the print paper P on which information is printed by the reciprocating operation of the print head H is conveyed to the cutting unit C, the conveyance is stopped when the cutting position of the print paper P reaches the cutting position of the disc-shaped cutter 22. . In this stop state, the operating mechanism 23 moves the disk-shaped cutter 22 in the main scanning direction, whereby the print paper P is cut into a print size.

  Next, the cut print paper P is printed with information specifying the order in the print head 24 of the back print unit D. Further, the print paper P is sent to the conveying roller 25, the correction roller 26, and the guide plate 27 of the decurling unit E so that the curl is corrected and then discharged onto the upper surface of the discharge tray 2.

[Details of print section]
In the print portion B, a pair of guide rods 13 having a circular cross section are arranged in a posture parallel to the main scanning direction. A carriage 10 is supported slidably with respect to the pair of guide rods 13, and an ink discharge unit 11 is connected to the lower surface side of the carriage 10. The lower surface of the ink discharge unit 11 is provided with an ink discharge surface 11a in which a large number of discharge holes are formed. In this embodiment, two ink ejection surfaces 11a that are separated from each other in the sub-scanning direction Y are provided.

  The carriage 10 is provided with a pair of slide guides 14 formed with circular holes so as to be fitted on the one guide rod 13 on one side surface in the sub-scanning direction, and the other guide rod 13 on the other side surface. The slide block 15 is provided with a recess that engages with the slide block 15. The carriage 10 is provided with a carriage cover 16 at the top.

  A timing belt type driving belt 19 wound around the driving pulley 17 and the idle pulley 18 is disposed along the main scanning direction on the side of the carriage. The driving belt 19 and the carriage 10 are connected to each other, and a rotational driving force is transmitted from the driving motor M to the driving pulley 17.

  As a linear encoder LE that acquires the position of the print head H in the main scanning direction, a strip-shaped linear strip 31 is fixed to the housing 1 at a position near the print head H in a posture parallel to the main scanning direction. The sensor unit 32 for optically acquiring the scale information is supported on the carriage 10 of the print head H via the substrate 33.

  As shown in FIG. 6, the linear strip 31 has a structure in which bar-shaped scale information 31a is printed at a predetermined interval on a band-like transparent resin member or the like. The substrate 33 is provided with a pair of wall bodies 34 projecting from the linear strip 31 so as to be close to both the front and back surfaces in the thickness direction (corresponding to the sub-scanning direction). It is fixed. The sensor unit 32 is configured as a photo interrupter type in which the light source module 32a and the photo sensor module 32b are arranged at positions facing each other.

  The linear encoder LE is configured as an incremental type that identifies the position of the print head H in the main scanning direction by counting the scale information 31a when the print head H moves. The drive pulley 17, the idle pulley 18, the drive belt 19, the drive motor M, and the like constitute a print head H moving mechanism.

  The control unit F acquires information such as images and characters to be printed, controls the transport mechanism A, controls the drive motor M based on a signal from the linear encoder LE, and synchronizes with the drive of the drive motor M. By controlling the drive mechanism built in the ink discharge unit 11, ink is discharged from the discharge holes of the ink discharge surface 11a to print information.

  At the time of printing, the position of the print head H in the main scanning direction is specified by the information from the linear encoder LE based on the home position HP. Further, the control unit F controls the operating mechanism 23 of the cutting unit C, controls the print head 24 of the back printing unit D, and controls the decurling unit E.

[Details of ink ejection surface]
As described above, the ink discharge unit 11 of the print head H is provided with two sets of ink discharge surfaces 11a that are separated from each other along the sub-scanning direction. As shown in FIG. 7, on each ink ejection surface 11a, a large number of ink nozzles are arranged vertically and horizontally, and the ink nozzles are C (cyan) nozzles Nc, M (magenta) nozzles Nm, Y (yellow) nozzles. Ny and K (black) nozzles Nk are arranged in a straight line in a total of 8 rows along the sub-scanning direction for each color. In each row, 180 nozzles are arranged. FIG. 7 is not a bottom view but a plan view seen through the ink ejection surface 11a from the top, for convenience of explanation of the following inspection method.

[About inspection method]
In this embodiment, an inspection method using only two rows of K (black) ink nozzles Nk provided on one ink ejection surface 11a will be described. The K ink nozzles Nk1 in the first row are located closer to the home position HP in the print head. On the other hand, the K ink nozzles Nk2 in the second row are close to the turning point TP and are sufficiently separated from the K ink nozzles Nk1 in the first row in the main scanning direction. This point is convenient as a nozzle used in an inspection method described later.

  Further, in this inspection method, only a part of the K ink nozzles Nk1 and Nk2 in each row is used. That is, as can be seen from the partially enlarged view of the ink nozzle Nk1 shown in FIG. 7, the 180 ink nozzles Nk1 arranged in the sub-scanning direction are divided into 15 groups of 12 for convenience, and the odd number of the groups Are used as inspection nozzles Ns1, and even-numbered groups sandwiched between them are idle nozzles Nr1 that are not used for inspection. Similarly, the nozzle used for inspection among the ink nozzles Nk2 in the second row is referred to as inspection nozzle Ns2.

Of the entire movement area of the print head H from the home position HP to the turn-back point TP, the remainder excluding the non-image forming areas provided at both ends is set as an image formable area. The print head H moves at a constant standard speed V (cm / second) in both the forward path and the return path in the image formable area.
For the print head H that is moved in the main scanning direction by the timing belt, the first discharge position, the second discharge position, the third discharge position,..., The seventh discharge position from the home position HP toward the turning point TP. Thus, a total of seven ejection positions for inspection are set for convenience.

[Inspection procedure]
(1) Chart creation step:
<1-1> The first position and the second position while the print paper P is not moved in the sub-scanning direction, and the print head H is moved from the home position HP to the turning point TP at the normal speed that is normally used (outward path). , The third position... The seventh position sequentially, one drop of ink of a predetermined size (first ink drop) from the first row of inspection nozzles Ns1 and the second row of inspection nozzles Ns2. Discharge.

Ejection is performed while moving the print head H at a standard speed V (cm / sec) until tired, and since there is a slight distance between the ink ejection surface 11a and the print paper P, the liquid droplets are slanted in the forward direction. Fly in the direction and land on the print paper P.
As shown in FIG. 8, when attention is paid only to the droplet Dg discharged from any one of the inspection nozzles Ns1, for example, during the forward movement at the fourth position P4, the standard toward the turning point TP is included in the droplet Dg. Since the velocity V (cm / sec) acts as a lateral initial velocity component, the droplet Dg flies diagonally toward the turning point TP and land.

<1-2> Next, while the print paper P is continuously fixed at the same sub-scanning position, the print head H that has passed the turn-back point TP is moved backward (return) to the home position HP at a standard speed. Print from the same first row of inspection nozzles Ns1 and second row of inspection nozzles Ns2 in the reverse order of the previous seven discharge positions of the seventh position, the sixth position, the fifth position,..., The first position. A second ink droplet having substantially the same size as the first ink droplet is ejected toward the paper P. The droplets fly in an oblique direction toward the return path and land on the print paper P.

  As shown in FIG. 9, when attention is paid only to the droplet Db discharged during the backward movement from the same inspection nozzle Ns1 as in the previous step at the same fourth position, the standard velocity V toward the home position HP is included in the droplet Db. Since (cm / sec) acts as a lateral initial velocity component, the droplet Db flies obliquely toward the home position HP and land. In general, the droplet Db landed on the return path is at a position displaced closer to the home position HP than the droplet Dg landed on the outbound path. Here, the distance on the printed paper P between the droplet Db landed on the return path and the droplet Dg landed on the forward path is called a landing point interval C1.

By the above operation, as illustrated in FIG. 10, a determination chart JC in which a certain pattern is printed on the print paper P is created.
The determination chart JC has a large number of 14 broken lines extending along the sub-scanning direction. These broken lines are referred to as a first group U1 formed by ejection at the moment when the print head H reaches the first position, a second group U2 at the second position, and a seventh group U7 at the seventh position. It is divided into seven groups.

  Here, for example, FIG. 11 shows an enlarged view of only the fourth group U4 in the center. In the fourth group U4, there are a broken line L1 created by the inspection nozzle Ns1 in the first row and a broken line L2 created by the inspection nozzle Ns2 in the second row. The broken line L1 is visually observed as eight dot groups L1a, L1b,... L1h arranged from the upstream side toward the downstream side along the sub-scanning direction. Similarly, the broken line L2 is also observed as a group of eight short linear dots L2a, L2b,... L2h.

  In the next interval determination step, as the simplest method, among these linear dot groups, the most upstream dot group L1a and downstream dot group L1h in the sub-scanning direction in the first row group, and A method will be described in which only four groups in total in the second row group, that is, the most upstream dot group L2a and downstream dot group L2h in the sub-scanning direction are focused.

  FIG. 12 shows a state in which the four dot groups L1a, L1h, L2a, and L2h are adjacently arranged in a further enlarged state. In each of the four dot groups, the left column in FIG. 12 shows the droplets Dg landed on the forward path moving toward the turning point TP, and the right column landed on the return path moving toward the home position HP. A droplet Db is shown.

  In the dot groups L1a, L1h, L2a, and L2h, the landing point intervals between the droplet Dg and the droplet Db in the return path are indicated by symbols C1a, C1h, C2a, and C2h, respectively. If the ink discharge surface 11a is not inclined with respect to the surface of the print paper P along either the X axis or the Y axis, all landing point intervals C1a, C1h, C2a, C2h should be equal to each other. is there.

(2) Interval determination step:
<2-1> The landing point intervals in the dot groups are compared along the main scanning direction (X axis). In the example shown in FIG. 12, for example, when a comparison is made between two dot groups L1h and L2h on the downstream side in the sub-scanning direction (Y) of the print paper P, the dot group L1h in the first row near the home position HP. It is determined that the landing point interval C1h between the droplet Dg in the forward path and the droplet Db in the return path is larger than the landing point interval C2h in the second row of dot groups L2a (C2h <C1h). . Even if the comparison is made between the two dot groups L1a and L2a on the upstream side in the sub-scanning direction (Y) of the print paper P, the same result (C2a <C1a) is obtained.

<2-2> Landing point intervals in the dot groups are compared along the sub-scanning direction (Y-axis). In the example shown in FIG. 12, for example, when comparison is made between two dot groups L1a and L1h near the home position HP, the landing point interval C1h in the downstream dot group L1h with respect to the sub-scanning direction (Y) Shows an example in which the distance is larger than the landing point interval C1a in the upstream dot group L1a (C1a <C1h). A similar result (C2a <C2h) is obtained even if the comparison is made between the two dot groups L2a and L2h located near the turn-back point TP.

  FIG. 13 shows the correspondence relationship between the landing point intervals C1a, C1h, C2a, C2h in the four dot groups L1a, L1h, L2a, L2h and the inclination state of the ink discharge surface 11a with respect to the surface of the print paper P ( It is the figure demonstrated exaggerating the inclination in order to help an understanding. The following inclination determination step is performed based on the correspondence illustrated in FIG.

(3) Inclination determination step:
<3-1> From the comparison result of the landing point intervals performed along the main scanning direction (X axis), the inclination component generated around the Y axis along the sub scanning direction is determined. In the example shown in FIG. 12 and FIG. 13, the landing point intervals C1a and C1h in the first row are larger than the landing point intervals C2a and C2h in the second row (C2a <C1a; C2h <C1h). The surface 11a has an inclination component (angle: θ1) around the Y axis with respect to the surface of the print paper P. In particular, the side near the home position HP in the ink discharge surface 11a is more than the side near the turn-back point TP. It is determined that the slope of the lifted form is exhibited. The magnitude of the angle θ1 can be estimated from the average value of the quotient of C1h ÷ C2h and the quotient of C1a ÷ C2a.

<3-2> From the comparison result of the landing point intervals performed along the sub-scanning direction (Y-axis), the inclination component generated around the X-axis along the main scanning direction is determined. In the example shown in FIGS. 12 and 13, the downstream landing point intervals C1h and C2h in the sub-scanning direction are larger than the upstream landing point intervals C1a and C2a (C1a <C1h; C2a <C2h). The ink discharge surface 11a has an inclination component (angle: θ2) around the X axis with respect to the surface of the print paper P. In particular, the downstream side in the sub-scanning direction in the ink discharge surface 11a is the upstream side. It is judged that the slope of the form which floated rather than is exhibited. Also, the magnitude of the angle θ2 can be estimated from the average value of the quotient of C1h ÷ C1a and the quotient of C2h ÷ C2a.

One of the simple and reliable methods for performing the interval determination step and the inclination determination step described above is a method of observing with the eyes using a magnifier or a microscope of about 10 to 50 times. It is also possible to determine the inclination by
In particular, in the comparison of the landing point intervals performed along the sub-scanning direction (Y axis), if there is an obvious inclination component, the landing point interval is changed to “c” from the upstream side along the Y axis toward the downstream side. Since the non-parallel state spreading in a letter shape is confirmed, the inclination determination by the naked eye is relatively easy.

Up to this point, the inspection method has been described only for the fourth group U4 formed in the center of the determination chart JC with respect to the main scanning direction, but the remaining first group U1-third formed in the determination chart JC. By performing the same inspection for all of the group U3 and the fifth group U5 to the seventh group U7, it is possible to obtain inclination information in individual regions over the entire length in the main scanning direction.
Based on the obtained inclination information, the print paper P on the ink discharge surface 11a can be obtained by reattaching the ink discharge surface 11a, the print head H, or the paper guide 12 in the suction unit, or adjusting the attachment posture. The inclination state with respect to can be improved. The inclination information can also be used as data for confirming the improvement status.

[Another embodiment]
<1> Judgment chart The reflective scanner that reads the dot pattern obtained on the JC and the landing point interval are determined from the read dot pattern and compared with each other, and the inclination components around the X axis and the Y axis are calculated. An inclination determination system including a computer program that automatically calculates and a monitor that displays the calculated inclination component may be used.

<2> Even when the ink discharge surface 11a has an inclination component generated around the Z axis perpendicular to the surface of the print paper P, this inclination state can be determined by the determination chart JC. That is, when the determination chart JC is visually observed, if it is confirmed that two adjacent groups of broken lines are displaced in the sub-scanning direction, as illustrated in FIG. 14, the ink discharge surface 11a. Can be determined to be inclined about the Z axis perpendicular to the surface of the print paper P. In the illustrated example, the ink discharge surface 11a is inclined counterclockwise around the Z axis perpendicular to the surface of the print paper P, and the broken line end of the fourth group U4 and the broken line of the fifth group U5. The length generated between the end and the same end is exaggerated as a “deviation” of S.

<3> Similarly, when the phenomenon of skewing of the print paper P is observed due to the problem of mounting accuracy of the rollers for conveying the print paper P, or the guide rod 13 for guiding the print head H is attached to the print paper P. Even when the vehicle is inclined, the inclination state can be determined by the determination chart JC. In this case, it is expressed as an inclination phenomenon between the side of the front end of the print paper P and the line segment connecting the ends of the broken lines of the groups U1-U7.

<4> The same tilt determination as in the above-described embodiment can be performed using a determination chart JC using nozzles of colors other than black (K) or a determination chart JC created using nozzles of all colors.

The perspective view which shows the main structures of a printing apparatus Vertical side view showing the main configuration of the printing device Plan view showing the operating system of the print head Perspective view of carriage printhead Side view of carriage printhead Perspective view showing the sensor unit Plan view and partial enlarged view showing the ink ejection surface Explanatory drawing showing the behavior of ink droplets in the print head Explanatory drawing showing the behavior of ink droplets in the return path of the print head Plan view showing the obtained judgment chart JC Partial enlarged view of judgment chart JC Enlarged view of four dot groups selected from judgment chart JC Explanatory drawing which shows the correspondence of the landing point space | interval and inclination state of each dot group Explanatory drawing which shows the pattern regarding the inclination around the Z axis

Explanation of symbols

A Transport mechanism B Print section C1a, C1h, C2a, C2h Landing point interval Dg Droplet (outward path)
Db droplet (return trip)
F Control unit G Ink reservoir H Print head HP Home position JC Determination charts L1, L2 Broken lines L1a, L1b,... L1h Dot group (HP side)
L2a, L2b,... L2h dot group (TP side)
Nk ink nozzle (for black)
Nr1 Resting nozzle Ns1, Ns2 Inspection nozzle P Print paper TP Turning point U4 4th group X Main scanning direction Y Sub scanning direction 10 Carriage 11 Ink ejection unit 11a Nozzle surface 12 Paper guide

Claims (6)

An inspection method for an ink jet printer comprising a print head having a discharge nozzle surface comprising a large number of ink nozzles and supported so as to be reciprocally movable along a main scanning direction with respect to a recording medium supported by guide means,
While moving a certain point in the main scanning direction in the forward direction, the first ink droplet is landed from the predetermined ink nozzle on the ejection nozzle surface toward the recording medium, and the predetermined ink nozzle is moved in the vicinity of the same point in the backward direction. A chart creation step for creating a determination chart made of the recording medium by landing the second ink droplets from the recording medium to the recording medium;
An interval determination step for determining a landing interval along the main scanning direction between the first ink droplet and the second ink droplet landed on the determination chart;
An inkjet printer inspection method comprising: an inclination determination step for determining an inclination state of the discharge nozzle surface with respect to the recording medium supported by the guide means based on the landing interval determined by the interval determination step. In the chart creating step, at least two ink nozzles separated from each other along the main scanning direction are used as the predetermined ink nozzles,
The ink jet printer inspection method according to claim 1, wherein, in the interval determination step, the landing interval indicated by one of the two ink nozzles is compared with the landing interval indicated by the other of the two ink nozzles. In the chart creating step, at least two ink nozzles separated in a direction perpendicular to the main scanning direction are used as the predetermined ink nozzles,
The ink jet printer inspection method according to claim 1, wherein, in the interval determination step, the landing interval indicated by one of the two ink nozzles is compared with the landing interval indicated by the other of the two ink nozzles.   4. The ink jet printer inspection method according to claim 1, wherein, in the chart creation step, a plurality of ink nozzles adjacently arranged along a sub-scanning direction of the print head are used as the predetermined ink nozzles. 5.   The inkjet according to claim 4, wherein the group of the predetermined ink nozzles composed of the plurality of ink nozzles is set so as to be adjacent to the next group of the predetermined ink nozzles with a pause ink nozzle not used for ejection interposed therebetween. Printer inspection method.   A determination chart created by the chart creating step of the inspection method according to claim 1.

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