JP2000071432A - Method and device for compensating troubled ink jet nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of maintaining a processing amount even when a non-operated nozzle exists. SOLUTION: A non-operated black printing nozzle is detected (112) and an alternative dot, formed of ink of not black, is printed at the position of picture element, whereat the dot will be printed ordinarily by the non-operated real black printing nozzle, supposing that the non-operated real black printing nozzle is operated (123). Respective alternative dots are constituted of more than one dot, not black or the constituting element, while respective alternative dots are constituted of synthetic or processed black dot formed of two or three inks of cyanide, magenta or yellow.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printing apparatus, and more particularly, to a technique for maintaining a throughput even when there is a nozzle that does not operate.

[0002]

2. Description of the Related Art Ink jet printers form a printed image by printing a pattern of individual dots at specific locations in a pixel array defined for a print medium. These locations are conveniently visualized as small dots in a linear array. These positions may be referred to as "dot locations", "dot positions", or "pixels". Therefore, the printing operation can be considered to be filling the dots of the ink with the pattern of the dot locations.

[0003] Ink jet printers print dots by ejecting very small drops of ink onto a print medium, and typically include a movable carriage that supports one or more printheads, each having a nozzle for ejecting ink. Including. The carriage traverses over the print media surface, the nozzles are controlled to eject ink droplets at appropriate times according to commands from a microcomputer or other control device, and the timing for applying the ink droplets is
It is intended to correspond to the pattern of pixels in the image being printed.

[0004] Color ink jet printers typically use a plurality of printheads mounted within a print carriage to produce a full range of colors. For example, in a printer with four printheads, each printhead can output a different color, and commonly used basic colors are cyan, magenta, yellow, and black. In a printer with two printheads, one printhead outputs black and the other outputs cyan, magenta and yellow from each of the nozzle sub-arrays.

[0005] The primary color is created on the media by depositing droplets of the required color on pixel locations, while a secondary or shaded color is a method in which multiple droplets of different primary colors are formed. Two or more base colors, created by depositing on the same or adjacent pixel locations and printing overlaid, create secondary colors according to established optical principles. That is, the base color dots are created by depositing drops of the required color, and the secondary or mixed colors are created by depositing a number of different base color drops. A secondary or mixed color dot can also be considered a plurality of overlapping dots, each of which is a base color.

One of the considerations in an ink jet printer that includes an array of black print nozzles and an array of non-black color print nozzles is that one or more black print nozzles fail. If this is not compensated for, image defects such as missing lines in a black area such as text will result. One known compensation technique is the multiple pass (multi-pass) print mode, which results in an increased number of prints and a reduced throughput. Therefore, there is a need to compensate for black print nozzle failure in a manner that does not reduce throughput.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method capable of maintaining a throughput even when there is a nozzle that does not operate.

[0008]

SUMMARY OF THE INVENTION The disclosed invention detects a non-working black printing nozzle and prints a replacement dot of non-black ink at the pixel location normally printed by the non-working black nozzle. Each of the alternative dots made of non-black ink is created by at least one non-black dot that is a component. According to one particular aspect of the present invention, the replacement dots made of non-black ink include composite or processed black dots made of two or more non-black constituent colors. For example,
Such non-black basic colors are selected from cyan, yellow or magenta.

[0009] Those skilled in the art will readily understand the advantages and features of the disclosed invention when reading the following detailed description together with the drawings.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS In the following detailed description and some of the drawings, the same elements are identified with the same reference numerals.

FIG. 1 is a perspective view of a large format inkjet printer / plotter 10 incorporating the teachings of the disclosed invention, thereby compensating for non-working black print nozzles without reducing throughput.

The printer 10 includes a housing 12 mounted on a stand 14. The housing has left and right drive mechanism housings 16,18. A control panel 20 is mounted on the right housing section 18. Carriage device 100 shown in phantom under cover 22
Is adapted to reciprocate along a guide rail 24, also shown in phantom, parallel to the carriage scan axis, which causes the carriage device 100 to move along the carriage scan axis. The position of the carriage device 100 on the carriage scan axis (ie, horizontal axis) is determined with respect to the encoder strip 120 (FIG. 2) by the carriage positioning mechanism 110 (FIG. 2). This is described more fully below with respect to FIG.
A print media 30 such as paper is positioned vertically, ie, along the media axis, by a media axis drive mechanism that includes a print roller 154 (FIGS. 2 and 3).

FIG. 2 shows a carriage device 100, a carriage positioning mechanism 110 and an encoder strip 12.
FIG. The carriage positioning mechanism 110
Including carriage position motor 112. A shaft 114 extends from the carriage position motor 112 through which the motor drives a small belt 116. Through a small belt 116, the carriage position motor 112 drives the idler 122 via its shaft 118. The idler 122 is a second idler 1
26 drives the tightened belt 124.
The belt 124 is attached to the carriage device 100 and slides through the carriage device 100.

The carriage device 10 on the carriage shaft
The position of zero is accurately determined using the encoder strip 120. The encoder strip 120 is secured by a first post 128 at one end and a second post 129 at the other end. Encoder strip 120 may be implemented in a manner as disclosed and claimed in commonly assigned US Pat. No. 5,276,970, which is incorporated herein by reference. As disclosed in this reference, a carriage axis encoder having an optical reader is located on the carriage device to provide a carriage position signal.

The carriage device 100 includes four ink jet printhead cartridges or pens 102 containing different color inks (eg, black, yellow, magenta, and cyan inks, respectively).
104, 106 and 108 are removably supported. As the carriage device 100 translates along the carriage scan axis, the printhead cartridge 10
Selected ink firing resistors of the 2, 104, 106 and 108 printheads are activated and ink drops are fired through the associated inkjet nozzles.

FIG. 3 is a simplified perspective view of the media positioning system 150 utilized in the printer of FIG. The media positioning system 150 includes the print roller 15
4 is included. Printing roller 1
The position of 54 is determined by the media position encoder 156. The media position encoder 156 has a plurality of openings 1
59, including a disk having the same. Optical reader 16
A zero provides a plurality of output pulses, thereby facilitating the determination of the position of the print roller 154 and thus the position of the print medium 30 (FIG. 1). Position encoders are well known in the art. For example, Hewlett-Packar
d Journal, October 1988, 99-106.
Howard C. announced on the page. Epstein
Economical High-Per by others
performance Optical Encoders
Please refer to.

As shown in FIGS. 1, 2 and 3, on the carriage device 100, an optical sensor module 200 is mounted. The sensor module is adapted to optically sense the test line printed by the printhead to determine misalignment of the printhead cartridge and adjust or compensate for it. By way of illustrative example, a sensor module 20 as disclosed in commonly assigned US Pat. No. 5,404,020, which is incorporated herein by reference.
0 is implemented by a phase plate and provided with a suitable processing circuit for processing its output.

Referring to FIG. 4, the modified print cartridge 100a includes a removably mounted single color ink cartridge 130 (for example, printing black) and a color cartridge such as cyan, magenta and yellow. Separate reservoirs 133, 134, 13 for different inks
6 is held.

Referring to FIG. 5, a further modified print cartridge 100b has a first three compartments having separate ink reservoirs 142, 144, 146 for different color inks such as yellow, light magenta, and dark magenta. Holds the ink cartridge 140. The adjacent second three-compartment ink cartridge 150 includes separate ink reservoirs 152, 154, 156 for inks of different colors, such as black, light cyan, and dark cyan.

Referring now to FIG. 6, a simplified block diagram of a control system for controlling the thermal ink jet printer of FIG. 1 capable of implementing the techniques of the present invention will be described. The control system includes an interface 51 that receives print data from a host computer and stores the print data in a buffer memory 53, for example. The microprocessor controller 55 processes the print data and stores raster data stored in a bitmap raster memory 57a included in a random access memory (RAM) 57 provided for use by the microprocessor controller 55. It is configured to generate. A read-only memory 59 is also provided as appropriate for use with microprocessor controller 55.

The print control device 61 transfers a part of the raster data from the bitmap raster memory 57a to the swath memory 63, and supplies the swath data to the print head drive control device 43. The printhead drive controller 43 may be used to control the ink in the printhead cartridges C1, C2, CN where the printhead cartridges are implemented as single color printhead cartridges and / or as multiple cartridges as described above with respect to FIGS. The print head driving device 67 for driving the ejection element is controlled. Print head cartridge C1, C2, C
N includes printheads P1, P2, PN, respectively, and a nozzle array N1, N2, NN that emits a single color or multiple colors, e.g., one nozzle array that emits multiple colors has one nozzle for each color. It is configured in a sub-array that emits ink drops.

The print head cartridges C1, C2,
It should be understood that the CN may include a printhead cartridge that receives ink from separate ink reservoirs R1, R2, RN, for example, via ink delivery tubes known to those skilled in the art. Alternatively, the printhead cartridge may include a self-contained printhead cartridge having a built-in ink reservoir that is not connected to a separate ink reservoir.

The print control device 61 further includes a print control device 6
The print roller 154 (FIG. 2)
And the medium axis drive motor 152 for moving the motor (FIG. 3). The medium position encoder 156 is a medium shaft drive motor 1
52 provides information for feedback control. Similarly, the carriage shaft encoder 73 is connected to the print control device 6.
1 for positioning the inkjet cartridge supporting carriage device 100 (FIGS. 1 to 3) in accordance with the carriage movement command from
Provide feedback information for feedback control of A multi-channel analog-to-digital (A / D) converter 75 receives an analog signal based on the output from the optical sensor 200 and provides a digital version of such an analog signal. The digital version of the analog signal is processed to determine printhead cartridge misalignment.

The print controller further includes a print cartridge C
Receives the output of the optical drop detection circuit 49 used to identify any nozzles that do not work. As an illustrative example, optical drop detection circuit 49 is disclosed in US Pat. No. 5,455,608, which is incorporated herein by reference in its entirety.
And the optical element and optical drop detection circuit disclosed in US Pat. No. 5,434,430.

Referring now to FIG. 7, the printer scans the print carriage along the carriage axis and prints dots at selected pixel locations P of a two-dimensional pixel array A defined for that print medium. To form an image. The pixel locations or pixels P are arranged in rows and columns, with the rows aligned with the carriage scan axis and the columns aligned with the media axis. The number of pixels per unit distance along the carriage scan axis is called the carriage axis resolution, and the number of pixels per unit distance along the medium axis is called the medium axis resolution. The center-to-center distance between adjacent columns is the carriage axis dot pitch, and the center-to-center distance between adjacent rows is the media axis dot pitch. Any arbitrary rows are printed by the print carriage at least once, ie, scanned, and after at least one pass of the print carriage, the media is advanced properly.

In accordance with the present invention, nozzles (single color ink cartridges or compartments of multiple ink cartridges) that print inactive (ie, faulty) true black are detected and the inactive true is normally disabled. Dots printed with one or more non-black color printing nozzles (e.g., a single color ink cartridge or compartment of multiple ink cartridges) are printed as replacement dots, A true non-black dot replacing a true black dot that would have been printed using a non-working true black print nozzle, if at all,
A substitute dot is composed of one or more non-black dots that are constituents, and each of the non-black dots that are constituents is made of non-black ink. If the substitute dot is made up of a plurality of non-black dots that are the constituent elements, the plurality of non-black dots that are the constituent elements overlap, and the substitute dot can be called a composite substitute dot. As an illustrative example, the constituent non-black dots may be made of a single color, such as cyan, magenta, or yellow.

[0027] Effectively, one or more non-black color printing nozzles do not work in the printing of dots that would be printed using the true black printing nozzles that would not work if they did. Used in place of true black nozzles, each of the non-black color printing alternative nozzles prints with a non-black ink, such as cyan, magenta, or yellow. As a specific example, the replacement dot includes a processed or synthesized black, and the replacement dot is printed using at least two non-black inks selected from, for example, cyan, magenta, or yellow inks. As another example, alternative dots include synthetic or processed black, made up of all overlapping cyan, magenta, and yellow dots.

Therefore, the non-black printing substitute nozzle prints a substitute dot at a predetermined pixel position. The first non-black printing alternative nozzle of the first color may be located in a nozzle array that includes, for example, a second non-black printing alternative nozzle of another color in a compartment of multiple cartridges. A nozzle array including a first non-black printing alternative nozzle and a second non-black printing alternative nozzle also includes:
A third non-black printing alternative nozzle can also be located. Alternatively, non-black printing alternative nozzles of different colors, each of which is not black, may be located in separate nozzle arrays, for example, in separate cartridges. As a specific example, a cyan print alternative nozzle is arranged in a nozzle array of a cyan print cartridge, a magenta print alternative nozzle is arranged in a nozzle array of a magenta print cartridge, and a yellow print alternative nozzle is arranged in a nozzle array of a yellow print cartridge. It is also possible to arrange in.

According to the present invention, as long as the non-uniformity caused by using the substitute dots is acceptable, the true black print nozzle will not operate without using a print mode that limits the throughput. The visual effect of image defects is reduced.

Referring now to FIG. 8, a flow diagram of an exemplary process for operating an inkjet printer according to the present invention will be described. At 111, the user of the inkjet printer selects a desired print quality, for example, best, normal, draft. At 113, the true black print nozzle that does not operate is detected by the droplet detection circuit 49 (FIG. 6).
Identified by At 115, a determination is made as to whether the black nozzle does not operate. If no, at 117 printing is performed using the standard print mode, and no substitute dots are used. 11
If the determination at 5 is yes, a determination is made at 119 as to whether the selected print quality is best. If yes, at 121 printing is performed using the multi-pass print mode to compensate for inactive black print nozzles.

If the determination at 119 is no, then at 123, an alternate dot made of non-black ink instead of the dot that would normally be printed by the inactive black print nozzle if it operated. Is used to perform printing. The replacement dot is formed by one or more dots that are non-black components. That is, one or more non-black color print nozzles replace the inactive true black print nozzles.

The foregoing discloses an ink jet printer in which non-black color print nozzles are replaced by failed black print nozzles to compensate for failed or inoperative black print nozzles, while maintaining throughput. Therefore, the processing amount increases as compared with the compensation by the multiple pass mode printing.

While the above is a description and illustration of specific embodiments of the invention, those skilled in the art will appreciate that they do not depart from the scope and spirit of the invention as defined by the appended claims. Various modifications and changes can be made.

The embodiments of the present invention have been described in detail above. Hereinafter, examples of each embodiment of the present invention will be described.

Embodiment 1 A method of operating an ink jet printer including a plurality of black printing elements and a plurality of non-black color printing elements, the method comprising: identifying an inactive black printing element; Printing a replacement dot with a plurality of non-black printing elements at predetermined pixel locations that would otherwise normally print with the black printing element.

[Embodiment 2] An embodiment wherein each of the substitute dots is provided with a dot having a color which is one of cyan, magenta and yellow, which is not black, which is a constituent element. 2. The method according to 1.

[Embodiment 3] The method according to embodiment 1, characterized in that each of said alternative dots comprises a plurality of overlapping non-black constituent dots.

[Embodiment 4] The method according to embodiment 3, wherein the non-black dots as the plurality of components have different colors.

[Embodiment 5] The non-black dots as the plurality of components include a cyan dot as a component, a magenta dot as a component, and a yellow dot as a component. And
The method according to embodiment 3.

[Embodiment 6] The method according to Embodiment 1, wherein each of said alternative dots comprises a synthesized black dot.

[Embodiment 7] The method according to embodiment 6, wherein the synthesized black dots comprise a plurality of overlapping non-black dots which are constituent elements.

[Embodiment 8] The non-black dots as the plurality of components include a cyan dot as a component, a magenta dot as a component, and a yellow dot as a component. And
Embodiment 8. The method according to embodiment 7.

[Embodiment 9] The step of printing with the plurality of non-black printing elements includes the steps of: first printing at a predetermined pixel position with a first non-black printing nozzle arranged in a first nozzle array; 3. The method of embodiment 1, comprising printing the first dot of

[Embodiment 10] The step of printing with the plurality of non-black printing elements includes the step of: placing the first non-black printing nozzle at the predetermined pixel position with a second non-black printing nozzle arranged in a second nozzle array. 10. The method of embodiment 9, further comprising the step of printing a second dot of a second color different from the color.

[Embodiment 11] The step of printing with the plurality of non-black printing elements may include the step of: placing the first non-black printing nozzle in the third nozzle array at the predetermined pixel position with the first non-black printing nozzle. Embodiment 10 further comprising the step of printing a third dot of a color and a third color different from the second color.
The method described in.

[Embodiment 12] The step of printing with the plurality of non-black printing elements includes the step of: printing a first color of a first color at the predetermined pixel position with a first non-black printing nozzle arranged in a nozzle array. And printing a second dot of a second color different from the first color at the predetermined pixel position with a second non-black printing nozzle disposed in the nozzle array. 2. The method of embodiment 1, comprising:

[Thirteenth Embodiment] A third non-black printing nozzle arranged in the nozzle array at the predetermined pixel position has a third color of a third color different from the first color and the second color. 13. The method according to embodiment 12, further comprising the step of printing the dots.

[Embodiment 14] The scanning print carriage (10
0), supported by the scanning printing carriage;
A plurality of black printing nozzles (102), a plurality of non-black color printing nozzles (104, 106, 108) supported by the scanning printing carriage, and a detection device (49) for detecting inactive black printing elements; Means (55, 61) for causing a plurality of non-black printing nozzles to print alternative dots at predetermined pixel positions where the inactive black printing nozzles would normally print if the black printing nozzles were to operate. An inkjet printer comprising:

[Embodiment 15] The ink jet printer according to embodiment 14, wherein the non-black color printing nozzle comprises a cyan printing nozzle.

[Embodiment 16] The ink jet printer according to embodiment 14, wherein the non-black color printing nozzle comprises a magenta printing nozzle.

[Embodiment 17] The ink jet printer according to embodiment 14, wherein the non-black color printing nozzle comprises a yellow printing nozzle.

[Embodiment 18] The ink jet printer according to embodiment 14, wherein the non-black substitute dot comprises a processed black dot.

[0053]

As described above, by using the present invention, the processing amount can be maintained even when there is a nozzle that does not operate.

[Brief description of the drawings]

FIG. 1 is a perspective view of a large format inkjet printer / plotter incorporating the teachings of the present invention.

FIG. 2 is a perspective view of a carriage device, a carriage positioning mechanism, and a print medium positioning mechanism of the printer / plotter of FIG.

FIG. 3 is a simplified perspective view of the printer / plotter media positioning system of FIG. 1;

FIG. 4 is a perspective view of another print carriage that can be used in the printer / plotter of FIG.

FIG. 5 is a perspective view of a further print carriage that can be used in the printer / plotter of FIG.

FIG. 6 is a simplified block diagram of a printer control device that controls the swath printer of FIG. 1;

FIG. 7 schematically illustrates a pixel array on which dots are selectively printed by the printer of FIG. 1;

FIG. 8 is a flow diagram of an exemplary procedure for operating an inkjet printer according to the present invention.

[Explanation of symbols]

 49: Detector 55: Means for printing alternative dots 61: Means for printing alternative dots 100: Scanning print carriage 102: Black printing nozzle 104: Nozzle for printing non-black color 106: Nozzle for printing non-black color 108: Nozzle to print non-black color

Claims (1)

[Claims] 1. A method of operating an inkjet printer including a plurality of black printing elements and a plurality of non-black color printing elements, the method comprising: identifying a non-working black printing element; Printing alternative dots with a plurality of non-black printing elements at predetermined pixel locations that would normally be printed with the black printing elements.