JP6010980B2 - Printing device - Google Patents

Description

  The present invention relates to printing inspection.

  An ink jet printing apparatus performs printing by ejecting ink from a plurality of nozzles. Some of the plurality of nozzles may be unable to eject ink due to some cause, or the amount and / or landing position of the ejected ink may be excluded from the set value. As a method of detecting such a defective nozzle, a method of optically inspecting whether a predetermined inspection pattern can be correctly printed on an inspection medium is known.

  When nozzles provided in a printer that uses a plurality of colors of ink are to be inspected, ink of the same color as the color of the inspection medium may be included. If the color of the inspection medium and the ink are the same, the accuracy of the optical inspection in the above method is reduced, and the inspection of the nozzle that ejects the ink of that color cannot be performed correctly.

  The following are known as techniques that take this into consideration. First, ink of a color different from the color of the inspection medium is discharged as a base. The ink of the same color as the color of the inspection medium is ejected over the ink to form an inspection pattern. In this way, the accuracy of inspection can be ensured even with ink having the same color as the color of the inspection medium (for example, Patent Document 1).

JP 2010-69637 A

  The problem of the prior art is that the amount of ink required for inspection increases in order to form the base.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

Application Example 1: A printing unit that forms a test pattern on a test medium using a first color ink and a second color ink different from the first color;
Inspecting dot formation with the first color ink in a first region having a first region color different from the first color in the region of the inspection medium on which the inspection pattern is formed. And performing a dot formation inspection with the second color ink, wherein the second area is different from the first area color and the second area of the inspection medium area on which the inspection pattern is formed. And an inspection unit for performing in a second region having color.

  According to this application example, since it is not necessary to print the base, the inspection can be executed without increasing the amount of ink to be ejected. The first color and the second region color may be the same or different from each other. The same applies to the second color and the first region color. In addition to the first and second colors, the printing unit and the inspection unit may target dots of inks of other colors.

Application Example 2: The printing apparatus according to Application Example 1,
The inspection medium is configured by adhering a member having the second region color to the back surface of a transparent medium,
The first region is a region facing a region where the member is not bonded on the surface of the transparent medium,
The second region is a region facing the region where the member is bonded on the surface of the transparent medium.
According to this application example, an inspection medium can be easily manufactured using a transparent medium as a raw material. Note that the medium of the inspection medium is transparent so long as it has a degree of transparency that allows the second color to be inspected for dot formation for the second color ink.

Application Example 3: The printing apparatus according to Application Example 1 or Application Example 2,
The inspection unit scans the inspection medium in a scanning direction, thereby executing inspection by a unit inspection range a plurality of times,
The first and second regions are arranged so as to appear alternately and at equal intervals along the scanning direction with respect to the inspection unit by the scanning.
The length of the unit inspection range in the scanning direction is not more than half the length of the first or second region in the scanning direction.
According to this application example, the first and second regions can be used efficiently. This is because at least one unit inspection range fits in each of the first and second regions.

Application example 4:
A printing apparatus according to Application Example 3,
The length of the inspection pattern in the scanning direction is at least 2.5 times the length of the unit inspection range in the scanning direction.

  According to this application example, it is not necessary to align the inspection pattern with respect to the arrangement of the first and second regions. This is because an inspection pattern is formed from end to end of at least one unit inspection range that fits in each of the first and second regions.

Application Example 5: The printing apparatus according to any one of Application Example 1 to Application Example 4,
The second color is white or transparent.
The previous application example may be performed in this way.

Application Example 6: The printing apparatus according to any one of Application Example 1 to Application Example 5,
The second region color is black.
The previous application example may be performed in this way.

Application Example 7: A test pattern is formed on a test medium using a first color ink and a second color ink different from the first color,
Inspecting dot formation with the first color ink in a first region having a first region color different from the first color in the region of the inspection medium on which the inspection pattern is formed. Done
Inspecting the dot formation with the second color ink, a second area color different from the second area color and the first area color is selected from the area of the inspection medium on which the inspection pattern is formed. The inspection method performed in the 2nd area | region which has.

Application Example 8: A test pattern is formed on a test medium using a first color ink and a second color ink different from the first color,
Inspecting dot formation with the first color ink in a first region having a first region color different from the first color in the region of the inspection medium on which the inspection pattern is formed. Done
Inspecting the dot formation with the second color ink, a second area color different from the second area color and the first area color is selected from the area of the inspection medium on which the inspection pattern is formed. A program for causing a printing apparatus to execute what is performed in the second area.

  Any of the above application examples can be realized by other forms. For example, a non-temporary storage medium for storing the program can be considered.

1 is a schematic configuration diagram of a printer. The figure which shows the film for an inspection. The flowchart which shows an inspection process. The figure which shows the relationship between the pattern of an inspection film, an inspection pattern, and a reading range. The figure for demonstrating a preferable relationship when the test | inspection pattern length D satisfy | fills.

1. Configuration of the printer 10 (FIGS. 1 and 2):
FIG. 1 is an explanatory diagram illustrating a schematic configuration of the printer 10. The printer 10 is an ink jet line printer. The printer 10 includes a control unit 20, print heads 51 to 56 (print heads 53 to 56 are not shown), a transport mechanism 60, and a reading mechanism 70.

  The transport mechanism 60 includes a transport roller 62, a transport motor 64, and a platen 66. The transport motor 64 transports the print medium P by rotating the transport roller 62.

  Print head 51 is black (K), print head 52 is cyan (C), print head 53 is magenta (M), print head 54 is yellow (Y), print head 55 is white (W), and print head 56 is clear. (CL: transparent color) ink is ejected. Cyan (C), magenta (M), yellow (Y), and black (K) inks are collectively referred to as normal inks. White (W) and clear (CL) inks are collectively referred to as special inks.

  The print heads 51 to 56 are line heads, and each has a plurality of heads therein. Each head has a nozzle on the surface (lower surface) facing the print medium P. The nozzles are arranged in a zigzag manner in each head. Each head is also arranged in a zigzag manner inside the print heads 51 to 56. With such a configuration, a resolution of 600 dpi is realized as a resolution in a direction orthogonal to the conveyance direction of the print medium P (hereinafter referred to as “line direction”).

  Each nozzle ejects ink droplets by a piezo method. By discharging the ink droplets, dots of each color are formed on the print medium P. By this dot formation, an image corresponding to the input image data is printed on the print medium P during normal printing. On the other hand, at the time of inspection of a defective nozzle described later, a predetermined inspection pattern is printed on the inspection film 100 (see FIG. 2) as the print medium P.

  The reading mechanism 70 is used in an inspection process to be described later, and includes a reading sensor 72 and a light source 74. The light source 74 is an LED that emits white light to the reading position of the reading sensor 72. The reading sensor 72 is a light receiving element that receives reflected light at a reading position. This light receiving element is a color CCD that measures the received light intensity of each of RGB light. By measuring the received light intensity of each of the RGB light, any color can be inspected with high accuracy. The resolution in the line direction of the reading sensor 72 is 600 dpi, which is the same as the resolution of dot formation.

  The control unit 20 includes a CPU, a RAM, and a ROM (not shown), and controls operations of the print heads 51 to 56 and the transport mechanism 60. The control unit 20 is connected to various interfaces and peripheral devices such as an operation panel 30 for performing various operations related to printing, a liquid crystal display 40 and the like.

2. Inspection film 100 (FIG. 2):
FIG. 2 shows the inspection film 100. 2A is a view of the inspection film 100 as viewed from the surface (printing surface), and FIG. 2B is a direction in which the inspection film 100 is orthogonal to the transport direction and the thickness direction of the inspection film 100. It is the figure seen from.

  The inspection film 100 has a configuration in which a plurality of black release papers 120 are attached to the back surface of a colorless and transparent transparent film 110. Each of the release papers 120 is pasted so that the length in the transport direction is the length L, and the distance between the release papers 120 is also the length L.

  As shown in FIG. 2A, an area facing the area where the release paper 120 is not attached is called a white area, and an area facing the area where the release paper 120 is attached is called a black area. Accordingly, when the inspection film 100 is observed from the reading sensor 72 side, the surface of the inspection film 100 is constituted by the white region and the black region.

  In FIG. 2B, the unevenness due to the release paper 120 is greatly shown. For the sake of illustration, the thickness of the transparent film 110 and the release paper 120 is shown to be thick, and the actual unevenness is small enough not to hinder the conveyance of the inspection film 100.

3. Defective nozzle inspection (Figure 3):
FIG. 3 is a flowchart showing the inspection process. The purpose of the inspection process is to detect an abnormality in the ejection state of ink from each nozzle provided in the print heads 51 to 56 (hereinafter also referred to as “nozzle failure”). Examples of the nozzle failure state include a state in which the nozzle is clogged with ink solidified in the nozzle, and a smaller amount of ink is ejected than the prescribed ink amount, a state where no ink is ejected at all, or a larger amount than the prescribed ink amount. There is a state where an amount of ink is ejected. In addition, there is a state in which the nozzle is deformed for some reason and ink is not ejected in a specified direction. The execution subject of the inspection process is the control unit 20. The trigger for starting the inspection process is that an instruction to start the inspection process is input via the operation panel 30.

  When the process is started, first, an inspection pattern is printed on the inspection film 100 set as the print medium P using the print heads 51 to 56 and the transport mechanism 60 (step S10).

  FIG. 4 shows an inspection pattern. As shown in FIG. 4, the inspection pattern is formed by a plurality of dots. Each of the inspection patterns shown in FIGS. 4A and 4B is for one of the colors, and shows a part in the line direction. As shown in FIG. 4, the length D in the conveyance direction of the inspection pattern is T = 2.5L. This pattern is formed in order for each color. The start position of the inspection pattern may be either a white area or a black area, and the position in the area is not limited.

  Next, the inspection patterns printed on the print medium P are sequentially read using the reading sensor 72 (step S20). The reading length T for one unit is T = 0.5L. The reading for one unit is continuously executed. (A) to (m) shown in FIG. 4 indicate a reading range for one unit. Similar to the pattern formation start position, the reading start position may be either a white area or a black area, and the position in the area is not limited.

  Finally, pass / fail determination is performed for each color (step S30), and the inspection process is completed. This pass / fail judgment is made based on a reading result (hereinafter referred to as “optimal result”) for one unit, which indicates with higher accuracy that the largest number of dots are formed for each color. Identification of which color ink is inspected is performed based on the ratio of received light intensity of each of RGB in the reading sensor. However, since it is difficult to identify white and clear based on the ratio of the received light intensity, the white and clear are identified based on the inspection pattern formation order.

  The optimum result shown in FIG. 4A is the reading range (e) for the normal ink and the reading range (c) for the special ink. The reading results of the reading ranges (a) and (f) are not optimal results because there are places where dots are not formed in the reading range. The reading results of the reading ranges (b) and (d) are not optimum results because the reading range extends over the white area and the black area. Regarding the remaining reading range (c) (e), the reading range (e), which is a white area in the case of normal ink, is more accurate, and in the case of special ink, the reading range (c), which is a black area, is improved. Since the accuracy is better, these are adopted as the optimum results.

  In the case of FIG. 4B, the reading range (j) is the optimum result for the normal ink, and the reading range (h) is the optimum result for the special ink. The reading results of the reading ranges (g) and (m) are not optimal results because there are places where dots are not formed in the reading range. The reading result of the reading ranges (i) and (k) is not an optimum result because the reading range extends over the white area and the black area. Regarding the remaining reading range (h) (j), the reading range (j) of the white area is more accurate in the case of normal ink, and the reading range (h) of the black area is better in the case of special ink. These are adopted as the optimum results because they are more accurate.

4). effect:
According to the embodiment, it is possible to accurately inspect nozzles that discharge ink of any color. This is because the inspection is performed on the basis of the result obtained in the white region for the normal ink and in the black region for the special ink.

  In the case of the present embodiment, the black ink as the normal ink and the black area have the same color, and the clear ink as the special ink and the white area have the same color. However, this effect is not obtained only when the ink color and the region color are the same as described above, and can also be obtained when there is a combination of similar colors that lowers the accuracy of inspection.

  Furthermore, since only ink ejection for forming the inspection pattern is required, unnecessary ink ejection is unnecessary. Furthermore, since the inspection film 100 is produced by attaching the release paper 120 to the transparent film 110, it can be prepared inexpensively and easily.

  Further, since it is not necessary to align the inspection pattern range and the reading range with respect to the arrangement of the white region and the black region of the inspection film 100, the inspection can be easily performed. Since the line printer is originally difficult to perform such alignment, this effect is particularly useful for the printer 10.

  In the present embodiment, the following two conditions are satisfied so that the alignment is not necessary. The first condition (hereinafter referred to as “condition 1”) is a reading range (hereinafter referred to as “condition 1”) that falls within the white area without straddling the white area and the black area within the reading range of the inspection pattern of each color. This means that there is at least one reading range (hereinafter referred to as “black reading range”) and a black reading range (hereinafter referred to as “black reading range”).

  The second condition (hereinafter referred to as “condition 2”) is based on the assumption that condition 1 is satisfied, and is within the inspection pattern range within the white reading range (hereinafter referred to as “white inspection range”). And at least one black reading range within the inspection pattern range (hereinafter referred to as “black inspection range”). The inspection result in the white inspection range is the optimum result for the normal ink, and the inspection result in the black inspection range is the optimum result for the special ink.

In order to satisfy the condition 1, it is only necessary to satisfy T <L. If T <L is satisfied, at least one of the white reading range and the black reading range will appear one day by repeating the reading. Further, the condition that at least one white reading range and at least one black reading range appear in an area where each of the white area and the black area is α (α is a natural number) is the following formula [1].
T ≦ {α / (1 + α)} L ... [1]
In the present embodiment, T = L / 2 is adopted so that the formula [1] holds even when α = 1. The expression [1] is established even when α = 1, which means that at least one reading range can be accommodated in each of the white area and the black area.

On the other hand, in order to satisfy the condition 2, in addition to the above equation [1], the following equation [2] may be satisfied.
D ≧ 2αL + T [2]
Equation [2] will be described with reference to FIG.

  FIG. 5 is a diagram for explaining conditions that are preferable when the inspection pattern length D is satisfied, specifically, the condition 2 described above. FIG. 5A shows the inspection pattern length D and the positional relationship between the white area and the black area. The inspection film 100 shown in FIG. 5A is schematically shown, in which “black” indicates a black region and “white” indicates a white region.

The condition that at least one of the white inspection range and the black inspection range appears is that the following equation [3] is satisfied in addition to the equation [1] being satisfied.
D ≧ (2α-1) L ... [3]
Assuming that the white inspection range appears, if the expression [3] is satisfied, α white areas are included in the range where the inspection pattern is formed. If the number of white areas is α, Formula [1] is also satisfied, so that at least one white reading range is included. Therefore, if the inspection pattern is formed so as to include α white regions, that is, the region shown as the central region in FIG. 5A, at least one white inspection range appears.

  On the other hand, (α−1) black areas are included in the central area. If the black reading range is included in the central area, the black reading range becomes the black inspection range. On the other hand, if the black area is not included in the central area, the black inspection area may appear in at least one of the end area A and the end area B that are adjacent to the central area.

  FIG. 5B is an enlarged view of the end regions A and B, with the central region omitted, when the black reading range is not included in the central region. When the black reading range is not included in the central region, both the end region A and the end region B include the black reading range. This is because the number of black regions included in the central region and the end region A is α, and at least one of them includes the black reading range. The same applies to the center region and the end region B.

  In addition, the end area A and the end area B have the same reading range arrangement. This is because the end region A and the end region B are 2α apart from each other, and the same reading area arrangement appears for each α. Here, in the end regions A and B, the position of the distance Q from the left end of the figure is the left end of the reading range. Q is an arbitrary value.

As shown in FIG. 5B, in order for at least one black reading range of the end region A and the end region B to be the black inspection range, the following equation [4] should be satisfied.
D− (2α−1) L ≧ {T + (LQT)} + (Q + T) [4]
By rearranging the equation [4], the above equation [2] is obtained.

  FIG. 5B shows a case where the left end of the inspection pattern length D coincides with the left end of the reading range of the end area A. Even in such a case, when the expression [2] is satisfied, at least one black reading range of the end area A and the end area B becomes the black inspection range. This relationship does not depend on the value of the distance Q.

  In this embodiment, based on D ≧ 2.5L obtained by substituting α = 1 and T = L / 2 into Equation [2], D = 2.5L is set in order to reduce the amount of ink to be used as much as possible.

5. Correspondence between embodiment and application example:
Step S10 corresponds to software for realizing the printing unit and steps S20 and S30 for realizing the inspection unit.

6). Other forms:
Embodiments of the present invention are not limited to the above-described embodiments, and various forms can be adopted without departing from the technical scope of the invention. For example, the technical features of the embodiments corresponding to the technical features in each embodiment described in the summary section of the invention are intended to solve part or all of the above-described problems or part of the above-described effects. Or, in order to achieve all, replacement and combination can be performed as appropriate. The technical features can be deleted as appropriate unless they are described as essential. In addition, for example, the following can be considered.

  The color of the ink ejected by the nozzle to be inspected and the color and shape of each region of the inspection film 100 may be different from those in the embodiment. The number of inks and the color of each region are not limited as long as they are 2 or more. The shape of the region may be any shape as long as a different region appears by scanning.

  The inspection medium may not be the inspection film 100. Even if it does not use the transparent film 110 and the release paper 120, what is necessary is just a structure from which a color differs for every area | region. For example, a print medium of a different color may be attached to the print surface (front surface) on a print medium that is not transparent. Alternatively, different colors may be printed in advance.

  The numerical values exemplified in the embodiment may be changed. For example, the relationship between the inspection pattern length D, the reading length T, and the length L of the white area and the black area may be changed. For example, the value may be changed within a range that satisfies the inequality shown in the embodiment. For example, when the equal sign of Expression [2] is satisfied, that is, when D = 2αL + T is satisfied, the margin for performing the inspection normally is small. Therefore, D may be increased. For example, when α = 1 and T = L / 2, D ≧ 3L may be set. Further, the lengths of the black area and the white area need not be the same.

The printer may be a serial type with a serial head. In this case, the inspection film may be configured so that white areas and black areas appear alternately in the scanning direction of the serial head.
The light source may be a fluorescent lamp, a xenon lamp, or the like.
The resolution of the CCD line sensor may be higher than the resolution in the line direction of the print head.

DESCRIPTION OF SYMBOLS 10 ... Printer 20 ... Control unit 30 ... Operation panel 40 ... Liquid crystal display 51 ... Print head 52 ... Print head 53 ... Print head 54 ... Print head 55 ... Print head 56 ... Print head 60 ... Conveyance mechanism 62 ... Conveyance roller 64 ... Conveyance Motor 66 ... Platen 70 ... Reading mechanism 72 ... Reading sensor 74 ... Light source 100 ... Inspection film 110 ... Transparent film 120 ... Release paper P ... Printing medium

Claims (5)

A printing unit that forms a test pattern on a test medium using a first color ink and a second color ink different from the first color;
Inspecting dot formation with the first color ink in a first region having a first region color different from the first color in the region of the inspection medium on which the inspection pattern is formed. And performing a dot formation inspection with the second color ink, wherein the second area is different from the first area color and the second area of the inspection medium area on which the inspection pattern is formed. An inspection section to be performed in a second region having a color ;
Equipped with a,
The inspection medium is configured by adhering a member having the second region color to the back surface of a transparent medium,
The first region is a region facing a region where the member is not bonded on the surface of the transparent medium,
The printing apparatus according to claim 2, wherein the second area is an area facing the area where the member is bonded on the surface of the transparent medium . The printing apparatus according to claim 1,
The inspection unit scans the inspection medium in a scanning direction, thereby executing inspection by a unit inspection range a plurality of times,
The first and second regions are arranged so as to appear alternately and at equal intervals along the scanning direction with respect to the inspection unit by the scanning.
The length of the unit inspection range in the scanning direction is not more than half the length of the first or second region in the scanning direction. The printing apparatus according to claim 2 ,
The length of the inspection pattern in the scanning direction is 2.5 times or more the length of the unit inspection range in the scanning direction. A printing apparatus according to any one of claims 1 to 3 , wherein
The printing apparatus, wherein the second color is white or transparent. A printing apparatus according to any one of claims 1 to 4 , wherein
The printing apparatus in which the second region color is black.

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