Patent Grant
9085151
This application claims priority from Japanese Patent Application No. 2012-044363 filed on Feb. 29, 2012, the entire subject matter of which is incorporated herein by reference.
The invention relates to a liquid droplet discharge apparatus such as line printer (e.g., inkjet printer) of an inkjet recording type and a liquid droplet discharge adjusting method thereof.
As a liquid droplet discharge apparatus, there have been known an inkjet printer having a recording head in which a plurality of nozzles discharging liquid droplets of ink is arranged in a nozzle array. While reciprocating the recording head in a main scanning direction, the printer discharges the liquid droplets of ink to a recording medium moving in a sub-scanning, so as to perform a recording operation. In the printer, a plurality of lines is recorded by scanning of one time. That is, the recording is performed in a recording area corresponding to a width of the nozzle array every main scanning.
When recording a deep color image on a recording medium on which ink easily blurs, such as normal sheet, the blur is conspicuous at a dry edge of the recording area, around which the ink is not colored. The blur overlaps at a boundary part of the two recording areas, so that a black line may occur.
The occurrence of the black line can be prevented by adjusting an amount of relative movement of the recording head and the recording medium in the sub-scanning direction. That is, an interval between the recording areas is increased every main scanning, so that it is possible to prevent the overlapping of the blur and to prevent the black line from occurring. However, when a light color image is recorded at the adjusted state, an amount of the ink is small, so that the blur is also small and a white line is generated between the recording areas.
If an amount of the movement of the sub-scanning every recording area were adjusted, in correspondence to an image to be recorded, it could be possible to prevent the black line or white line. However, the control thereof is complicated.
Thus, there have been proposed a technology in which a liquid droplet discharge head having a nozzle array having a plurality of large nozzles arranged at a central part and a nozzle array having a plurality of small nozzles arranged at an end portion is used. According to this related-art technology, when discharging liquid droplets, the small nozzles discharge the liquid droplets at a boundary part of the recording area by the large nozzles, so that the occurrence of the line at the boundary part may be reduced.
Illustrative aspects of the invention provide a liquid droplet discharge apparatus and a liquid droplet discharge adjusting method thereof with which a line (black line, white line), which is generated in performing a recording operation on a recording medium, is made not to be conspicuous.
According to one illustrative aspect of the invention, there is provided a liquid droplet discharge apparatus comprising: a liquid droplet discharge head comprising a plurality of nozzles arranged in a plurality of arrays along a first direction; and a control unit configured to control the liquid droplet discharge head to discharge liquid droplets from the plurality of nozzles toward a recording medium while relatively moving the recording medium and the liquid droplet discharge head in a second direction orthogonal to the first direction, and form a plurality of dot arrays in the second direction, the dots of the array being arranged in the first direction, so as to form an image on the recording medium. The plurality of nozzles comprises: a plurality of main nozzles that is arranged in the first direction and is configured to discharge liquid droplets of main dots having a first diameter, and a plurality of sub nozzles that is arranged at end portion sides of arrays of the main nozzles and is configured to discharge liquid droplets of sub dots having a second diameter that is smaller than the first diameter. The control unit is configured to control the liquid droplet discharge head to form sub dot arrays by the liquid droplets discharged from the sub nozzles in two arrays with being staggered at a predetermined interval in the second direction between main dot arrays by the liquid droplets discharged from the main nozzles, so as to form the dot arrays.
<General Overview>
According to the above-described related-art technology, the sub-scanning is performed such that a recording position (liquid droplet discharge position) on the recording medium by the small nozzles is deviated in an array direction of the nozzle array from a period of an ink discharge position on the recording medium by the large nozzles in a previous main scanning or next main scanning. Due to this, it is difficult to perform the minute adjustment corresponding to each printer.
Further, there have been proposed a line printer in which a plurality of recording heads is arranged in parallel. In this printer, end nozzles of respective units are adjacent to each other at a boundary between the adjacent heads. Thus, when a pitch between the end nozzles of the units being laid over deviates from a preset nozzle pitch, a white line or black line may be generated in performing the recording operation on the recording medium, like the above serial type.
Therefore, illustrative aspects of the invention provide a liquid droplet discharge apparatus and a liquid droplet discharge adjusting method thereof with which a line (black line, white line), which is generated in performing a recording operation on a recording medium, is made not to be conspicuous.
According to a first illustrative aspect of the invention, there is provided a liquid droplet discharge apparatus comprising: a liquid droplet discharge head comprising a plurality of nozzles arranged in a plurality of arrays along a first direction; and a control unit configured to control the liquid droplet discharge head to discharge liquid droplets from the plurality of nozzles toward a recording medium while relatively moving the recording medium and the liquid droplet discharge head in a second direction orthogonal to the first direction, and form a plurality of dot arrays in the second direction, the dots of the array being arranged in the first direction, so as to form an image on the recording medium. The plurality of nozzles comprises: a plurality of main nozzles that is arranged in the first direction and is configured to discharge liquid droplets of main dots having a first diameter, and a plurality of sub nozzles that is arranged at end portion sides of arrays of the main nozzles and is configured to discharge liquid droplets of sub dots having a second diameter that is smaller than the first diameter. The control unit is configured to control the liquid droplet discharge head to form sub dot arrays by the liquid droplets discharged from the sub nozzles in two arrays with being staggered at a predetermined interval in the second direction between main dot arrays by the liquid droplets discharged from the main nozzles, so as to form the dot arrays.
According to the above configuration, based on the image data, the control unit forms the sub dot arrays formed by the sub nozzles in two arrays with being staggered at a predetermined interval in the second direction between the main dot arrays formed by the main nozzles. According thereto, a so-called white line or black line is prevented from occurring at a part (boundary part) between recording areas of the main dot arrays by the two sub dot arrays of the liquid droplets discharged from the sub nozzles. As a result, it is possible to improve a quality of an image to be formed on the recording medium.
According to a second illustrative aspect of the invention, the control unit comprises a deviation amount change unit configured to change discharge timing of the sub nozzles so as to change the predetermined interval.
According to the above configuration, the discharge timing of the sub nozzles is changed by the control unit, so that the predetermined interval is simply changed. Therefore, it is possible to easily adjust the interval that is optimal for avoiding the occurrence of the so-called white line or black line.
According to a third illustrative aspect of the invention, a sub nozzle array by the plurality of sub nozzles is formed at a position deviating in the second direction from a main nozzle array by the plurality of main nozzles.
According to the above configuration, the sub nozzle array is beforehand formed at a position deviating in the second direction from the main nozzle array. Therefore, the sub dot arrays are formed in two arrays with being staggered at the interval in the second direction between the main dot arrays even without changing the discharge timing.
According to a fourth illustrative aspect of the invention, the liquid droplet discharge apparatus further comprises a plurality of liquid droplet discharge heads arranged in parallel. The liquid droplet discharge heads adjacent to each other are staggered in the second direction and the sub nozzles of the liquid droplet discharge heads adjacent to each other are arranged to overlap in the first direction.
According to the above configuration, even when a plurality of liquid droplet discharge heads is provided, the so-called white line or black line is prevented from occurring at the boundary part between the recording areas to be recorded by the respective heads. As a result, it is possible to improve a quality of an image to be formed on the recording medium.
According to a fifth illustrative aspect of the invention, the liquid droplet discharge apparatus is a serial printer. The liquid droplet discharge head is configured such that: sub nozzle arrays by the plurality of sub nozzles are arranged at both ends of a main nozzle array by the plurality of main nozzles; and the sub nozzle arrays arranged at both ends of the main nozzle array are staggered in opposite directions with respect to the main nozzle array.
According to the above configuration, also in the serial printer, the sub dot arrays are formed in two arrays with being staggered at a predetermined interval in the second direction. According thereto, the so-called white line or black line is prevented from occurring, so that it is possible to improve a quality of an image to be formed on the recording medium.
According to a sixth illustrative aspect of the invention, the plurality of sub nozzles is configured such that a nozzle pitch thereof in the first direction is smaller than that of the plurality of main nozzles.
According to a seventh illustrative aspect of the invention, the plurality of sub nozzles is configured such that a nozzle pitch thereof in the first direction is irregular.
According to the above configuration, by adjusting the discharge timing or discharge amount of the sub nozzles, it is possible to finely set the predetermined interval of the sub dot arrays over a wide range.
According to an eighth illustrative aspect of the invention, there is provided A liquid droplet discharge adjusting method using the liquid droplet discharge apparatus, the method comprising: comparing shadings of an image formed by a main dot array of liquid droplets discharged from the plurality of main nozzles and an image formed by a sub dot array of liquid droplets discharged from the plurality of sub nozzles; and adjusting the predetermined interval to match the shadings.
Here, the shadings are evaluated by the well-known technique, for example by seeing the same with eyes or by reading a printed sample with a scanner and measuring a density thereof.
According to the above configuration, it is possible to manufacture the liquid droplet discharge apparatus capable of preventing the so-called white line or black line from occurring and improving a quality of an image to be formed on the recording medium.
According to the illustrative aspects of the invention, as described above, the sub dot arrays are formed in two arrays with being staggered at a predetermined interval in the second direction between the main dot arrays. Thus, the so-called white line or black line is prevented from occurring at the part (boundary part) between the recording areas of the main dot arrays by the two sub dot arrays. As a result, it is possible to improve a quality of an image to be formed on the recording medium.
Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings.
As shown in
The head unit 2 is arranged above (e.g., the sheet front of
In the respective recording heads 10A, 10B, as shown in
Each of the recording heads 10A, 10B has a flow path unit 20 that configures a liquid flow path communicating with the plurality of nozzles 13. A lower surface of the flow path unit 20 is a liquid droplet injection surface 15 having the plurality of nozzles 13 opened.
The flow path unit 20 has a substantially rectangular parallelepiped outward shape. The flow path unit 20 is provided at both end portions in the first direction A with two fixing parts 22 for fixing the flow path unit 20 to the head holding member 11 so that they protrude from side surfaces of the flow path unit 20. An upper surface of the flow path unit 20 is provided with an ink supply part 23 that is connected to an ink cartridge (not shown) by a tube 29 (refer to
The head holding member 11 is configured to hold the recording heads 10A, 10B is a plate-shaped member. The head holding member 11 is connected to a frame member 12 at both end portions in the first direction A. The frame member 12 is fixed to a housing 6 of the printer 1. The head holding member 11 is formed with mounting holes 11a corresponding to the respective recording heads 10A, 10B. At a state where the flow path units 20 of the recording heads 10A, 10B are respectively inserted into the mounting holes 11a, each of the flow path units 20 is fixed to the head holding member 11 at the two fixing parts 22 protruding from the side surfaces thereof by screws and the like.
A lower end portion of the flow path unit 20 protrudes more downward from the head holding member 11 through the mounting hole 11a of the head holding member 11. An edge of the head holding member 11 is fixed to the frame member 12. Incidentally, the respective recording heads 10A, 10B are supplied with the ink from the ink cartridge (not shown) mounted to the housing 6 of the printer 1 through the tube 29.
The conveyance mechanism 3 includes a supply roller 16 and a discharge roller 17, which are disposed to position the head unit 2 backward and forward, and are configured to move the recording sheet S along the platen 5 in the second direction B relative to the head unit 2 by the two rollers 16, 17.
The printer 1 is configured to discharge the liquid droplets of ink toward the recording sheet S from the nozzles 13 of the two recording heads 10A, 10B while moving the recording sheet S in the second direction B by the rollers 16, 17 of the conveyance mechanism 3. According thereto, a plurality of dot arrays N, the dots of the array being arranged along the first direction A, is formed in the second direction B, so that a desired image is formed on the recording sheet S.
The printer 1 includes a maintenance unit 4 configured to perform maintenance on the head unit 2 and a wiper 27. The maintenance unit 4 is positioned at the right side of the platen 5 when the maintenance is not performed. On the other hand, when performing the maintenance, the maintenance unit 4 is moved to a position facing the head unit 2 by a position switching mechanism (not shown).
The maintenance unit 4 has a cap member 18 made of an elastic member such as rubber, a suction pump 19 connected to the cap member 18 and the wiper 27 configured to wipe off the ink attached on the liquid droplet discharge surfaces 15 of the recording heads 10A, 10B. The cap member 18 is moved upward and downward by a cap elevating mechanism (not shown) having a driving source such as motor and a power transfer member such as gear. When the cap member 18 is pressed to the head unit 2 and a lip part 18a of an outer periphery thereof is closely adhered at a state where the head unit 2 is positioned at the maintenance position, the cap member covers the liquid droplet discharge surfaces 15 of the recording heads 10A, 10B at a time. The suction pump 19 performs a so-called suction purge operation of depressurizing the inside of the cap member 18 at a state where the cap member 18 covers the liquid droplet discharge surfaces 15 of the recording heads 10A, 10B so as to forcibly discharge the ink from the respective nozzles 13 of the two recording heads 10A, 10B.
The wiper 27 is made of an elastic member such as rubber. The wiper 27 is configured to move relative to the head unit 2 at a state where a tip thereof is closely adhered to the liquid droplet discharge surfaces 15 of the recording heads 10A, 10B, so as to wipe off the ink attached on the liquid droplet discharge surfaces 15 after the suction purge has been performed. Incidentally, when performing the maintenance, the head unit 2 may be moved relative to the maintenance unit 4, so that both may face each other.
In the below, an electrical configuration of the printer 1 will be described on the basis of the control device 31 of the printer 1. The control device 31 of the printer 1 shown in
The CPU is configured to execute the various programs stored in the ROM, so that the microcomputer and the calculation circuits operate as a recording control unit 31B (one example of a control unit). The storage unit 31A stores therein setting values and the like that are used in a variety of controls to be executed by the control device 31. The control device 31 is connected with a PC 70 that is an external apparatus and an operation panel 71 having a display, an operation button and the like. The recording control unit 31B is configured to control the recording heads 10A, 10B of the head unit 2 and the conveyance mechanism 3, based on image data and the like input from the PC 70.
The recording control unit 31B has a discharge timing adjusting unit 31Ba configured to adjust discharge timings of the respective nozzles 13. In the below, a case is described in which an inspector adjusts the discharge timings of the nozzles 13 by using the discharge timing adjusting unit 31Ba in a factory before the shipping. At a state where the manufacturing of the printer 1 is substantially completed, i.e., the discharge timings of the main nozzles 13a and the sub nozzles 13b are initialized, the inspector enables the nozzles 13 (13a, 13b) to actually discharge liquid droplets, so as to perform a recording operation on the recording sheet S. From the recording operation, the inspector compares and evaluates shadings of an image, which is formed by the main dot arrays of the liquid droplets discharged from the main nozzles 13a, and an image, which is formed by the sub dot arrays of the liquid droplets discharged from the sub nozzles 13b, by the well-known technique. It is necessary to compare and evaluate the shadings of the images formed by the liquid droplets discharged from the respective nozzles 13 in high precision. Therefore, it is preferable that the inspector should perform the evaluation with an equipment of the manufacturer before a user uses the printer, i.e., before the shipping.
Based on a result of the comparison and evaluation, the inspector re-sets the discharge timings of the sub nozzles 13b (e.g., an amount of deviation from the discharge timing of the main nozzles 13a) stored in the storage unit 31A for each sub nozzle array so that the shadings substantially coincide with each other. That is, for each sub nozzle array, the inspector re-records the discharge timings of the respective sub nozzles 13b, which are initially set for the recording heads 10A, 10B, with the discharge timings at which the shadings of the image by the main dot array (e.g., one array) and the image by the sub dot arrays (e.g., two arrays) substantially coincides with each other, by using the PC 70.
For example, when the discharge timings of the sub nozzles 13b arrays are set to highly deviate from the discharge timing of the main nozzle 13a array, an interval between the sub dot arrays NA22, NB22 in the second direction B is increased, as shown in
Therefore, when the user actually uses the printer (e.g., when recording an image and the like), the discharge timing adjusting unit 31Ba sets the discharge timing of the main nozzles 13a and the discharge timing of the sub nozzles 13b, which deviates by a predetermined time period from the discharge timing of the main nozzles 13a, with respect to the recording heads 10A, 10B, so that the shadings of the image formed by the main dot array and the image formed by the sub dot arrays substantially coincide with each other. As described above, the discharge timings are stored in the storage unit 31A as the recording control information. Whenever the recording data is input from the PC 70 to the control device 31 and an image and the like are recorded on the recording sheet S, the discharge timing adjusting unit 31Ba reads out the discharge timings from the recording control information stored in the storage unit 31A and performs a recording operation.
According thereto, the interval of the two sub dot arrays formed between the main dot arrays has a size with which a so-called white line or black line is invisible
Therefore, the so-called white line or black line is prevented from occurring, so that it is possible to manufacture the line printer 1 capable of forming a high-quality image on the recording sheet S.
Here, as shown in
Further, as shown in
According to the printer 1, the recording control unit 31B controls the discharge timing of the sub nozzles 13b based on the recording control information so that the discharge timing of the sub nozzles 13b deviates by a predetermined time period from the discharge timing of the main nozzles 13a on the basis of the image data. Accordingly, the sub dot arrays NA12, NB12 are formed in two arrays at a predetermined interval in the second direction B between the main dot arrays NA11, NB11. The interval has a size with which the so-called white line or black line is not conspicuous owing to the two sub dot arrays at the part (e.g., boundary part) between the recording areas by the main dot areas.
The invention can be also implemented in various modified embodiments.
(i) As shown in
Further, after reading out a test pattern by a scanner and seeing a density of the image, the deviation amount change unit 31Bb may be enabled by operating the operation panel 71 of the printer 1. Further, in addition to the timing change information about the discharge timings of the sub nozzles 13b, a plurality of amounts of liquid droplets to be discharged from the sub nozzles 13b may be pre-stored in the storage unit 31A as the liquid droplet change information so that the amount of liquid droplets can be also changed based on the above change instruction.
(ii) As shown in
According thereto, it is possible to form the sub dot arrays NA42, NB42 in two arrays with being staggered at a predetermined interval in the second direction B between the main dot arrays NA41, NB41 even without changing the discharge timing of the sub nozzles 13b relative to the main nozzles 13a.
(iii) In the above-described exemplary embodiment, the nozzle pitch is constant in the first direction. However, the nozzle pitch is not necessarily constant. For example, the nozzle pitches of the main nozzle array and the sub nozzle array may be changed. Further, like recording heads 10A2, 10B2 shown in
Also in these cases, as shown in
(iv) In the above-described exemplary embodiment, the case where the two recording heads are provided has been described. However, the invention can be also applied to a case where a plurality of recording heads is arranged in a zigzag shape. For example, as shown in
(v) In the above-described exemplary embodiment, the invention is applied to the line printer having the head unit of a fixed type including the plurality of liquid droplet discharge heads that is arranged in parallel and whose positions are fixed upon the image recording. In the printer, the liquid droplet discharge heads adjacent to each other are staggered in the second direction B, and the sub nozzles of the liquid droplet discharge heads adjacent to each other are arranged to overlap in the first direction A. The invention is not limited to the head-fixed type. For example, the invention can be also applied to a printer having a head unit of a serial type that discharges liquid droplets of ink toward the recording sheet S while moving in a width direction (e.g., a direction orthogonal to the conveyance direction of the sheet) of the recording sheet S. In this serial type, as shown in
The illustrative and modified embodiments relate to the case where the invention is applied to the printer of an inkjet recording type (one example of the liquid droplet discharge apparatus) discharging the ink to thus form an image and the like on the recording sheet. However, the invention is not limited thereto. For example, the invention can be applied, irrespective of the type and utility of the liquid to be discharged and the technical field. For example, the invention can be also applied to an apparatus that discharges liquid other than the ink, for example coloring liquid to thus manufacture a color filter of a liquid crystal display apparatus, an apparatus that discharges conductive liquid to thus form an electric wiring, and the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-044363 | Feb 2012 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5384587 | Takagi et al. | Jan 1995 | A |
| 6846064 | Yamane | Jan 2005 | B2 |
| 20040021730 | Yamane | Feb 2004 | A1 |
| 20070242098 | Sudo et al. | Oct 2007 | A1 |
| 20100231644 | Otokita | Sep 2010 | A1 |
| Number | Date | Country |
|---|---|---|
| 2003-305853 | Oct 2003 | JP |
| 2010-208120 | Sep 2010 | JP |
| 2010-208121 | Sep 2010 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20130222454 A1 | Aug 2013 | US |
