Patent Application
20120194588
1. Technical Field
The present invention relates to a printing apparatus and a printing method.
2. Related Art
In an ink jet type printing apparatus, among a plurality of nozzles for discharging ink included in a print head, in some cases, ink is not discharged or an ink discharging amount and an ink droplet shot position are improper in some nozzles, for some reason, whereby nozzles having a defective discharging state of ink (hereinafter, also referred to as defective nozzles) may be generated. From the related art, as techniques of detecting the defective nozzles, for example, JP-A-2010-058361, JP-A-2006-069027, JP-A-2006-069028, and JP-A-2010-194839 are known.
JP-A-2010-058361 discloses a technique which detects the defective nozzles by reading an inspection pattern printed on margins of paper by a image sensor. Furthermore, JP-A-2006-069027 and JP-A-2006-069028 disclose a technique which detects the defective nozzles by reading the inspection pattern printed on a transparent film from the back side of the printed surface by an image sensor (an image pickup element). Furthermore, JP-A-2010-194839 discloses a technique of using a matter in which a base by black ink is printed on a portion of a pattern of white ink as an inspection pattern, and then a pattern of white ink is printed.
However, in the techniques of JP-A-2010-058361, JP-A-2006-069027 and JP-A-2006-069028, when a difference in color between the discharged ink and the paper is small, a change in characteristic amount to be detected by the sensor becomes smaller, and detection accuracy drops. For example, in a case of printing the white ink or transparent ink on white paper, there is a high possibility of it not being possible to detect the defective nozzle.
Furthermore, in the technique of JP-A-2010-194839, the detection accuracy of the defective nozzle of the white ink is improved, but there is an extra need for a basic printing processing by black ink in the printing of the inspection pattern, and there was a problem to be improved in terms of time required for detection of the defective nozzle.
An advantage of some aspects of the invention is to provide a technique which enables the detection of the defective nozzles of various inks to accurately be performed.
A printing apparatus includes a print head having a plurality of nozzle groups which discharges multiple types of ink, respectively; a print control section which controls the operation of the print head, and prints inspection patterns of each ink on a transparent medium; a sensor which reads the inspection patterns printed on the transparent medium; a background color switching section which faces the sensor with the inspection pattern interposed therebetween and in which the background color is switched; and a defect determination section which determines an occurrence of a defective nozzle based on a reading result in which the background color and the inspection pattern are read by the sensor.
According to the printing apparatus, since it is possible to switch the background color depending on the type of ink and increase a difference in intensity of light between a portion of ink read by the sensor and a portion of the background, it is possible to accurately perform the detection of the defective nozzles of various inks.
The printing apparatus according to Application Example 1, wherein the background color switching section switches the background color depending on the type of ink of the read inspection pattern.
The printing apparatus according to Application Example 1 or 2, wherein the background color switching section has a background plate.
The printing apparatus according to Application Example 1 or 2, wherein the background color switching section has a film.
The printing apparatus according to Application Example 1 or 2, wherein the background color switching section has a liquid crystal panel.
The printing apparatus according to any one of Application Examples 1 to 5, wherein the multiple types of ink include at least one of white ink and transparent ink, and when the type of ink of the read inspection pattern is the white ink or the transparent ink, the background color is black.
According to the printing apparatus, when the type of ink of the read inspection pattern is the white ink or the transparent ink, the background color is set to black, whereby a difference in intensity of light between the portion of the white ink or the transparent ink read by the sensor and the portion of the background can be the largest. Thus, it is possible to accurately perform the detection of the defective nozzle of the white ink or the transparent ink.
The printing apparatus according any one of Application Examples 1 to 6, wherein the multiple types of ink include a plurality of color inks, when the type of ink of the read inspection pattern is one color ink among the plurality of color inks, the background color includes at least a component of a complementary color in a color circle of the one color.
According to the printing apparatus, when the type of ink of the read inspection pattern is one color among a plurality of color inks, the background color is set to color including at least the component of the complementary color in the color circle of the one color, whereby it is possible to increase a difference of intensity of light of the complementary color between the portion of ink read by the sensor and the portion of the background. Thus, the detection of the defective nozzle of the one color ink can be accurately performed, whereby it is possible to accurately perform the detection of each defective nozzle of the plurality of color inks.
The printing apparatus according to Application Example 7, wherein, when the type of ink of the read inspection pattern is one color ink among the plurality of color inks, the background color is the complementary color in the color circle of the one color.
According to the printing apparatus, the type of ink of the read inspection pattern is one color of the plurality of color inks, the background color is set to the complementary color in the color circle of the one color, whereby the difference of intensity of light of the complementary color between the portion of ink read by the sensor and the portion of the background can be the largest. Thus, it is possible to accurately perform the detection of the defective nozzle of one color ink, whereby the detection of each defective nozzle of the plurality of color inks can more accurately be performed.
A printing method includes printing an inspection pattern of each ink on a transparent medium by the use of a print head having a plurality of nozzle groups which discharges multiple types of ink, respectively; reading the inspection pattern printed on the transparent medium by the use of a sensor; switching a background color by the use of a background color switching section which faces the sensor with the inspection pattern interposed therebetween and in which the background color is switched when reading the inspection pattern; and determining an occurrence of a defective nozzle based on a reading result in which the background color and the inspection pattern are read, by the sensor.
According to the printing method, since it is possible to switch the background color depending on the type of ink and increase a difference in intensity of light between the portion of ink read by the sensor and the portion of the background, it is possible to accurately perform the detection of the defective nozzles of various inks.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
The invention will be described based on an embodiment.
The transport mechanism 60 includes a transport roller 62, a transport motor 64, and a platen 66. The transport motor 64 transports a print medium P passing between the printer head 50 and a flat plate-shaped platen 66 by rotating the transport roller 62 in a direction (hereinafter, referred to as a transport direction) perpendicular to an axial direction of the transport roller 62.
The ink cartridges 51 to 56 include back (K), cyan (C), magenta (M), yellow (Y), white (W), and clear (CL) inks. In addition, back (K), cyan (C), magenta (M), and yellow (Y) inks are collectively called a normal ink, and white (W) and clear (CL) ink are collectively called a special ink.
The printer head 50 is a line head type printer. On a surface (a lower surface)thereof facing the print medium P, a row of ink discharging nozzle generally placed in a row for each ink color is arranged along a transport direction of the print medium P. The Individual nozzles include piezoelectric elements, and vibration of the piezoelectric element is controlled by adjusting the voltage to be applied to the piezoelectric element to discharge ink droplets. Thus, on the print medium P to be transported by the transport mechanism 60 in the transport direction, dots by ink discharged from each nozzle provided in the printer head 50 are formed. As a result, during normal printing, on a paper as the print medium P, an image corresponding to the image data input as a print target is printed. Furthermore, when inspecting a defective nozzle described below, an established inspection pattern is printed on an inspecting transparent film as the print medium P.
The reading mechanism 70 of
The background color switching mechanism 80 is placed to face the reading mechanism 70, and switches the background color of an inspecting transparent film as the print medium P transported to the reading position of the image sensor 72, depending on the type of ink of the inspection pattern printed on the inspecting transparent film, when inspecting the defective nozzle.
When the inspecting transparent film as the print medium P sequentially formed with the dots by each ink as the inspection pattern passes through an optical path of the illumination light emitted by the light source 74 through the transportation by the transport mechanism 60, the light source 74 irradiates a portion of the inspecting transparent film corresponding to the reading position of the image sensor 72 with the illumination light, and the image sensor 72 senses the reflective light returning via the inspecting transparent film and the background plate 81. As a result, the image sensor 72 reads the inspection pattern printed on the inspecting transparent film for each line passing through the reading position by the transportation.
In addition, the image sensor 72 is placed so that it can sufficiently sense the reflective light from the print medium P and the background plate 81 in the reading position as a relative position relationship between the image sensor 72 and the light source 74. The image sensor 72 is constituted by a CCD line sensor, and resolution thereof in the line direction is identical to the interval S (720 dpi) of the nozzles. However, the resolution of the CCD line sensor may be any value in a possible range if the resolution is equal to or greater than the resolution of the line direction of the printer head 50.
The control unit 20 of
The image processing section 21 performs the image processing which converts an image data (also called an input image data) of a print target input from a computer or the like via an interface (not shown), or the inspection pattern data stored in the ROM in advance into the print data. Furthermore, the image processing section 21 creates the image data (also called a reading image data) from the signal that is output from the reading mechanism 70 via the reading control section 23.
The print control section 22 outputs the control signal, which controls the discharging of each nozzle, to the printer head 50 based on the print data after the image processing. In addition, the print control section 22 controls the operation of the transport mechanism 60.
The reading control section 23 controls the operation of the reading mechanism 70 and the background color switching mechanism 80 when inspecting the defective nozzle, executes the reading of the inspection pattern printed on the inspecting transparent film as the print medium P, controls the operation of the image processing section 21, and executes the creation of the reading image data.
The defect determination section 24 performs the determination presence or absence of an occurrence of the defective nozzle and the specification of the defective nozzle, based on the reading image data and the inspection pattern data read by the reading mechanism 70.
As mentioned above, the printer 10 starts the printing processing based on the input image data when information on the printing such as the printing image data, the number of printing sheet, or the printing size is input. Furthermore, the printer 10 executes the printing processing based on the inspection pattern data, the reading of the print pattern printed on the inspecting transparent film, and the defect determination, when the start instruction is input via the interface or via the operation panel 30. The present embodiment is characterized by the inspection of the defective nozzle, and the inspection of the defective nozzle will be described below.
The inspection of the defective nozzle is a process of detecting abnormality of the discharge state (hereinafter, also called a nozzle defect) of ink from each nozzle 581 included in the printer head 50. The nozzle defect, for example, includes a state in which the nozzle is clogged by ink solidified in the nozzles, a state in which ink is not discharged by a defined amount, or a state in which ink is not completely discharged, on the contrary, a state in which ink is discharged more than the defined amount or the like. In addition, there is a state in which the nozzle is deformed for some reasons, and ink is not discharged in the defined discharging direction. The nozzle, in which abnormality is generated in the discharging state of ink, is called a defective nozzle.
In the inspection of the defective nozzle of the present embodiment, as described below, the printing based on the inspection pattern data is performed by the use of a colorless inspecting transparent film as the print medium P, the printed inspection pattern is read, and it is detected whether or not the nozzle defect is generated based on the obtained reading image data and the inspection pattern data.
By discharging ink from the nozzle row of the odd number and, then discharging ink from the nozzle of the even number, with respect to the print medium P transported under the printer head 50, the inspection pattern corresponding to one nozzle row is formed. The inspection pattern is constituted by the dot rows along the transport direction. In the present example, one dot row is constituted by 100 dots. Furthermore, in order to form the dot row by every other nozzle arranged in the line direction, two dot row groups (regions surrounded by dashed lines) arranged at an interval (in the present example, 360 dpi) twice the nozzle interval S in the line direction are formed in a row in the transport direction. One dot row group is called an “inspection pattern”. Furthermore, in the present example, the inspection pattern is pattern by every other nozzle arranged in the line direction, and two inspection patterns are formed in one nozzle row. When the two inspection patterns are particularly distinguished, for example, the patterns are referred to as an “even nozzle inspection pattern” and an “odd nozzle inspection pattern”. In addition, the inspection patterns of other inks are also identical to the inspection pattern of black shown in
Moreover, in step S20 of
As is understood from
In the case of the clear ink, as is understood from
Even in the case of the white ink, like the case of the clear ink, as shown in
Considering the points mentioned above, it is understood that the background color when reading the inspection pattern may be set as below.
In addition, the inspection pattern is preset and the position of the printing is also known, if the background color is switched depending on the position of the print medium P transported to the reading position based on information, it is possible to switch the background color depending on the type of ink of the inspection pattern.
Moreover, in step S30 of
In the case of the cyan (C) ink, light to be detected in the sensor section of red (R) of the image sensor 72 which is a complementary color is greatly changed between the section with the printed dot row and the section with no the printed dot row. Specifically, as shown in
In addition, the same is also true for other normal inks, and each ink of magenta (M), yellow (Y), and black (K). However, the nozzle defect is determined by light detected in the sensor section of G light in the case of magenta (M), and the nozzle defect is determined by light detected in the sensor section of B light in the case of yellow (Y). In the case of black (K), the nozzle defect is determined by an average value of light detected in the sensor section of R light, G light and B (light). Furthermore, a value may be used in which the gradation values of each R, G, and B are added by a predetermined weighing but not the average value.
In the case of white (W) ink, light detected in each sensor section of R light, G light and B light of the image sensor 72 is greatly changed in the section with the printed dot row and the section with no the printed dot row. Specifically, as shown in
In the case of the clear (CL) ink, like the case of the white ink, light detected in each sensor section of R light, G light, and B light of the image sensor 72 is also greatly changed in the section with the printed dot row and the section with no the printed dot row. Specifically, as shown in
In the present example, when inspecting the defective nozzle, the colorless transparent film is used as the print medium and the inspection pattern is printed thereon. When reading the printed inspection pattern by the image sensor, in a case where the type of ink of read inspection pattern is the normal ink of black (K), cyan (C), magenta (M), and yellow (Y), the background color is set to white, and in the case of a special ink of white (W) and clear (CL), the background color is set to black, whereby the reading of the inspection pattern is executed. As a result, it is possible to solve the problem in that it is difficult to perform the detection of the defective nozzle of white (W) or clear (CL) ink, as described in the example of the related art, and to improve a time required for the detection of the defective nozzle.
As mentioned above, the background color switching mechanism is not limited to the background color switching mechanism 80 of the embodiment mentioned above, but, like the modified examples shown in
In addition, the invention is not limited to the embodiments mentioned above, but can be carried out in various forms in the scope not departing from the gist thereof, and, for example, the modifications as below are also possible.
In the embodiments mentioned above, cyan (C), magenta (M), yellow (Y), and black (K) are used as the normal ink, however, if any ink absorbs light of wavelength components of a visible light region, without being limited thereto, the ink can be used as the normal ink. As the normal ink, for example, it is possible to use a special color ink such as red (R), green (G), blue (B), and orange (Or) to be used for widening a color reproduction region, a light shade ink such as light cyan (LC), light magenta (LM), gray (LK), and light gray (LLK), or the like.
In the embodiment mentioned above, a case was described as an example where the background color of the normal ink is switched to white, and the background colors of white (W) and clear (CL) as the special ink are switched to black. However, there is no need to limit the background color of the normal ink to white, the background color may be switched depending on the type of ink. For example, cyan (C) may switch the complementary color of red (R) as the background color, magenta (M) may switch the complementary color of green (G) as the background color, and yellow (Y) may switch the complementary color of blue (B) as the background color, respectively. In this case, the same effect can also be obtained. Furthermore, the complementary color is not necessarily required, in the color circle, at least, color (color including at least the complementary color), which is situated at a complementary color side to color of ink becoming the target and reflects the color light of the complementary color, may be switched as the background color. However, it is preferable to use color of the range equal to or less than ±60°, more preferably, ±30°, on the basis of the complementary color of the color of ink becoming the target. Furthermore, the complementary color of the color of ink becoming the target is most preferable. The reason is because it is possible to increase a difference in intensity of light of the reflective light in the dot and the reflective light in the background color.
That is, the invention may switch the background color of the reading position depending on the type of ink of the inspection pattern and perform the reading of the inspection pattern in the reading position.
In the embodiment mentioned above, the colorless inspection film was described as an example, but if a difference in intensity of the reflective light between the background color and the dot can be detected, colorlessness may not be used.
In the embodiment mentioned above, the line head was described as an example, but, the invention is not necessarily limited thereto, and if a print head having a plurality of nozzles each discharging multiple types of ink is used, the invention can be applied to a printer (a printing apparatus) having any print head.
In the embodiment mentioned above, a part of the configuration realized by hardware may be switched to software, and on the contrary, a part of the configuration of software may be switched to hardware.
The entire disclosure of Japanese Patent Application No. 2011-016160, filed Jan. 28, 2011 is expressly incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-016160 | Jan 2011 | JP | national |
