JP2012213965A - Liquid ejection apparatus and control method thereof - Google Patents

Abstract

Variations in the ejection amount of a liquid are suppressed with a simple configuration.
A liquid ejecting apparatus includes a liquid ejecting head that ejects liquid supplied from a liquid storage unit as droplets onto a landing target, and a liquid supply path to the liquid ejecting head or a liquid storage unit. 22 includes a detection unit 62 that detects the pressure of the liquid and a control unit 62 that corrects the number of droplets ejected per unit area of the landing target 200 according to the detected pressure.
[Selection] Figure 3

Description

  The present invention relates to a technique for ejecting a liquid such as ink.

  In a liquid ejecting apparatus in which a recording head ejects ink supplied from an ink cartridge, there is a problem in that the ink ejection amount varies due to variation in ink supply pressure. In the technique of Patent Document 1, in order to suppress fluctuations in the ink ejection amount, the ink ejection amount is controlled according to the ink supply pressure.

JP 2009-202381 A

  By the way, in the technique of Patent Document 1, correction of the drive signal itself (for example, change of potential fluctuation width or pulse width) is performed in order to control the ejection amount of ink. Since a complicated configuration is required to correct the drive signal, problems such as an increase in failure rate and an increase in manufacturing cost may occur. In view of the above circumstances, an object of the present invention is to suppress fluctuations in the ejection amount of liquid with a simple configuration.

  In order to solve the above problems, a liquid ejecting apparatus of the present invention is a liquid ejecting apparatus including a liquid ejecting head that ejects liquid supplied from a liquid storage unit as droplets onto a landing target, and the liquid ejecting head A detection unit that detects the pressure of the liquid in the liquid supply path or the liquid storage unit, and a control unit that corrects the number of ejections of the droplet with respect to the unit area of the landing target according to the detected pressure With. “Detecting pressure” implies both detecting (specifying) pressure according to predetermined information (operation history, etc.) and detecting pressure directly by a sensor or the like. In the above configuration, the number of droplet ejections is corrected according to the supply pressure of the liquid supplied to the liquid ejecting head (the pressure of the liquid in the supply path or the liquid storage unit). Even in the case of a change, it is possible to suppress fluctuations in the ejection amount of the liquid (maintaining the ejection amount at a target value).

  The liquid ejecting apparatus according to a preferred aspect of the present invention includes a storage unit that stores ejection information that defines the number of ejections, and the control unit determines the number of ejections defined by the ejection information according to the pressure. to correct. In the above aspect, the number of injections defined by the injection information is corrected according to the pressure.

  In a preferred aspect of the present invention, the liquid ejecting head can eject the droplets having a plurality of different weights, the ejection information defines the number of ejections for each weight, and the control unit includes: The number of injections specified by the injection information is corrected for each weight according to the pressure. In the above aspect, since the correction is performed for each weight of the droplet, the variation in the injection amount is further suppressed as compared with the configuration in which the correction is performed based only on the pressure. In addition, since the supply pressure and the ejection characteristics are different for each color of the liquid, it is more preferable that the ejection information defines the number of ejections for each color of the liquid because the occurrence of a color difference is reduced.

  In a preferred aspect of the present invention, the storage unit stores an operation history of the liquid jet head, and the detection unit detects (identifies) the pressure according to the operation history. In the above aspect, since the pressure is detected (specified) according to the operation history, another configuration for detecting the pressure is unnecessary, and the configuration of the liquid ejecting apparatus can be simplified. The operation history means an operation history that affects the supply pressure of the liquid supplied to the liquid ejecting head. For example, the operation history is set according to the total amount of liquid ejected from the liquid ejecting head in the past.

  In a preferred aspect of the present invention, the storage unit stores an elapsed time from a reference time, and the detection unit detects (identifies) the pressure according to the elapsed time. In the above aspect, since the pressure is detected (specified) according to the elapsed time, another configuration for detecting the pressure is unnecessary, and the configuration of the liquid ejecting apparatus can be simplified.

  The detection unit of the liquid ejecting apparatus according to a preferred aspect of the present invention is a pressure sensor that detects a pressure of the liquid in the supply path or the liquid storage unit. In the above aspect, since the accurate pressure is detected by the pressure sensor and used for correction, the correction accuracy is further improved.

  The present invention is also specified as a method for controlling the liquid ejecting apparatus according to each of the above embodiments. The control method of the liquid ejecting apparatus according to the present invention is a liquid ejecting apparatus including a liquid ejecting head that ejects liquid supplied from a liquid storage unit as droplets onto a landing target, and the liquid supply path to the liquid ejecting head Alternatively, the pressure of the liquid in the liquid storage unit is detected, and the number of droplets ejected with respect to the unit area of the landing target is corrected according to the detected pressure. “Detecting pressure” implies both detecting (specifying) pressure according to predetermined information (operation history, etc.) and detecting pressure directly by a sensor or the like. Even with the above control method, the same operation and effect as the liquid ejecting apparatus of the present invention are realized.

1 is a schematic diagram of a printing apparatus according to a first embodiment of the present invention. 3 is a plan view of an ejection surface of a recording head. 1 is a block diagram including an electrical configuration of a printing apparatus according to a first embodiment. It is a wave form diagram of a drive signal. 6 is a graph showing the relationship between ink supply pressure and ink ejection weight. It is a figure which shows the table which matches operation | movement history and supply pressure. It is a figure which shows the table which matches supply pressure and a correction value. It is explanatory drawing which shows the specific example of correction | amendment of the frequency | count of injection. It is a block diagram of the printing apparatus in 2nd Embodiment. It is a figure which shows the structure of color ID. It is explanatory drawing which shows the specific example of correction | amendment of the frequency | count of injection. 6 is a graph showing the relationship between ink ejection amount and color difference. It is a block diagram of the printing apparatus in 3rd Embodiment. It is a graph which shows the relationship between elapsed time and ink supply pressure.

<A: First Embodiment>
FIG. 1 is a partial schematic view of an ink jet printing apparatus 100 according to a first embodiment of the present invention. The printing apparatus 100 is a liquid ejecting apparatus that ejects fine ink droplets onto the recording paper 200, and includes a container holding unit (cartridge holder) 10, a carriage 12, a moving mechanism 14, and a conveying mechanism 16.

  The container holding unit 10 includes a plurality of ink cartridges 22 (22K, 22Y, 22M, 22C) filled with inks of different colors (black (K), yellow (Y), magenta (M), cyan (C)). Is held detachably. The container holding unit 10 is fixed to a housing (not shown) of the printing apparatus 100. That is, the printing apparatus 100 according to the first embodiment employs an off-carriage method in which the ink cartridge 22 is not mounted on the carriage 12.

  A recording head 24 is mounted on the carriage 12. Ink in each ink cartridge 22 is supplied in parallel to the recording heads 24 via a supply path 26 (tube) from each of the plurality of ink cartridges 22 to the recording head 24. The recording head 24 functions as a liquid ejecting head that ejects ink supplied from each ink cartridge 22 onto the recording paper 200.

  FIG. 2 is a plan view of the ejection surface 32 of the recording head 24 that faces the recording paper 200. As shown in FIG. 2, a plurality of nozzle rows 34 (corresponding to different colors (black (K), yellow (Y), magenta (M), cyan (C)) are formed on the ejection surface 32 of the recording head 24. 34K, 34Y, 34M, 34C) are formed at intervals in the X direction. Each nozzle row 34 is a set of a plurality of nozzles (ejection ports) N arranged on a straight line at intervals in the Y direction perpendicular to the X direction. Black (K) ink supplied from the ink cartridge 22K is ejected from each nozzle 56 of the nozzle row 34K. Similarly, the yellow (Y) ink of the ink cartridge 22Y is ejected from each nozzle 56 of the nozzle row 34Y, and the magenta (M) ink of the ink cartridge 22M is ejected from each nozzle 56 of the nozzle row 34M, and the ink cartridge 22C. The cyan (C) ink is ejected from each nozzle 56 of the nozzle row 34C. It is also possible to arrange the plurality of nozzles 56 of each nozzle row 34 in a staggered manner.

  The moving mechanism 14 in FIG. 1 reciprocates the carriage 12 in the X direction (main scanning direction). The position of the carriage 12 is detected by a detector (not shown) such as a linear encoder and used for controlling the moving mechanism 14. The transport mechanism 16 transports the recording paper 200 in the Y direction (sub-scanning direction) in parallel with the reciprocation of the carriage 12. A desired image is recorded (printed) on the recording paper 200 by the recording head 24 ejecting ink onto the recording paper 200 during the reciprocation of the carriage 12.

  FIG. 3 is a block diagram including an electrical configuration of the printing apparatus 100. In FIG. 3, only one ink cartridge 22 is representatively shown for convenience. As illustrated in FIG. 3, the printing apparatus 100 includes a control device 102 and a print processing unit (print engine) 104. The print processing unit 104 is an element that records an image on the recording paper 200, and includes the moving mechanism 14, the transport mechanism 16, and the recording head 24 described above.

  The recording head 24 includes a plurality of ejection units U corresponding to different nozzles 56 in each nozzle row 34 and a drive circuit 42 that drives each ejection unit U by supplying a drive signal COM. Each of the plurality of injection units U includes a pressure chamber 52, a nozzle 56, and a piezoelectric element 54. The pressure chamber 52 is a space communicating with the nozzle 56 and filled with ink supplied from the ink cartridge 22. The ink in the ink cartridge 22 is supplied to the recording head 24 at the supply pressure P. The pressure at the ink supply port of the recording head 24 (the end of the supply path 26 on the recording head 24 side) corresponds to the supply pressure P. The supply pressure P depends on the height of the ink level in the ink cartridge 22. The piezoelectric element 54 vibrates according to the drive signal COM supplied from the drive circuit 42. As the piezoelectric element 54 varies the pressure of the ink in the pressure chamber 52, an ink droplet is ejected from the nozzle 56. Large dots or small dots are formed on the recording paper 200 according to the weight of the ejected ink droplets.

  The control device 102 in FIG. 3 is an element that controls the entire printing apparatus 100, and includes a control unit 62 and a first storage unit 64. The first storage unit 64 is configured by a storage circuit such as a ROM or a RAM, for example, and stores a control program and various types of information (for example, an operation history H and tables TH, TL, TS). The control unit 62 instructs the operation of each ejection unit U to the drive circuit 42 for each printing cycle in accordance with print data supplied from an external device. Specifically, either an ejection of an ink droplet (large ink droplet) for forming a large dot or an ejection of an ink droplet (small ink droplet) for forming a small dot is selectively instructed.

  The drive circuit 42 selects a predetermined section from the drive signal COM in accordance with an instruction from the control unit 62 and supplies the selected section to each ejection unit U for each printing cycle. FIG. 4 is a diagram illustrating an example of the drive signal COM. The drive signal COM includes an ejection pulse PD1 and an ejection pulse PD2. The ejection pulse PD1 and the ejection pulse PD2 are waveforms that drive the piezoelectric element 54 to eject ink droplets from the nozzle 56. The ejection pulse PD1 corresponds to ejection of a large ink droplet, and the ejection pulse PD2 corresponds to ejection of a small ink droplet. The weight of the large ink droplet ejected by the supply of the ejection pulse PD1 exceeds the weight of the small ink droplet ejected by the supply of the ejection pulse PD2.

  FIG. 5 is a graph showing the relationship between the ink supply pressure P to the recording head 24 (horizontal axis) and the ink ejection weight W (vertical axis) for each of large ink droplets and small ink droplets. The ink supply pressure P to the recording head 24 decreases as the amount of ink in the ink cartridge 22 decreases. As can be understood from FIG. 5, the ink ejection weight W decreases as the ink supply pressure P to the recording head 24 decreases. In addition, the rate at which the ink ejection weight W decreases according to the supply pressure P (the rate of change of the ejection weight W) is larger for large ink drops than for small ink drops.

  Against the background described above, the control unit 62 controls the ink ejection amount in accordance with the ink supply pressure P to the recording head 24. The control unit 62 according to the first embodiment controls the number N (NL, NS) of ink ejection per unit area of the recording paper 200 according to the ink supply pressure P. Specifically, the control unit 62 first detects (specifies) the supply pressure P according to the operation history H, and secondly, the number N of injections per unit area of the recording paper 200 (NL, NS). Is corrected by a correction value A (AL, AS) corresponding to the supply pressure P. The number of large ink droplet ejections NL per unit area is corrected according to the correction value AL, and the number of small ink droplets ejection per unit area NS is corrected according to the correction value AS. The correction value AL and the correction value AS are individually set according to the supply pressure P.

  The first storage unit 64 in FIG. 3 stores the operation history H of the recording head 24 for each nozzle row 34. In the first embodiment, the operation history H of each nozzle row 34 indicates the cumulative ejection amount S of ink ejected from the nozzle row 34. The operation history H is updated as needed in parallel with the printing operation by the recording head 24. When the ink cartridge 22 is replaced, the operation history H (cumulative ejection amount S) corresponding to the ink cartridge 22 (nozzle row 34) is initialized.

  A table TH referred to by the control unit 62 to detect (specify) the supply pressure P corresponding to the operation history H is stored in the first storage unit 64. As shown in FIG. 6, the table TH is a table that associates each numerical value (S1, S2,...) Of the operation history H (cumulative injection amount S) with each numerical value (P1, P2,...) Of the supply pressure P. . The relationship between the supply pressure P and the cumulative ejection amount S in the table TH is statistical or experimental so that the supply pressure P decreases as the cumulative ejection amount S increases (that is, the ink amount in the ink cartridge 22 decreases). Is determined in advance.

The table TL and the table TS referred to by the control unit 62 in order to specify the correction value A (AL, AS) corresponding to the supply pressure P specified from the table TH are stored in the first storage unit 64 (FIG. 7). . The table TL associates each numerical value of the supply pressure P with each numerical value of the correction value AL of the number of large ink droplet ejections NL per unit area. Specifically, the table TL indicates that the correction value AL increases as the value of the supply pressure P decreases (that is, the number of large ink droplet ejections (NL + AL) increases) and the correction value AL. Correlate with AL. For example, each correction value AL in the table TL is set statistically or experimentally so that the total ejection weight of large ink droplets per unit area substantially matches a predetermined target value regardless of the supply pressure P. Similarly, in the table TS, each value of the supply pressure P is corrected and corrected so that the correction value AS increases as the value of the supply pressure P decreases (that is, the number of small ink droplet ejections (NS + AS) increases). Corresponds to each numerical value AS. For example, each correction value AS in the table TS is set statistically or experimentally so that the total ejection weight of small ink droplets per unit area substantially matches a predetermined target value regardless of the supply pressure P.
As described above, the ratio at which the ejection weight W of the large ink droplets decreases with the decrease in the supply pressure P exceeds the ratio at which the ejection weight W of the small ink droplets decreases. Therefore, each numerical value (AL, Table TL) of the table TL and the table TS is set such that the rate at which the correction value AL increases with respect to the decrease in the supply pressure P exceeds the rate at which the correction value AS increases with respect to the decrease in the supply pressure P AS) is selected. That is, the difference between the correction value AL and the correction value AS, that is, the difference between the number of large ink droplet ejections (NL + AL) and the number of small ink droplet ejections (NS + AS) increases as the supply pressure P decreases.

  The control unit 62 specifies, for each nozzle row 34, the correction value AL of the large ink droplet corresponding to the supply pressure P estimated from the operation history H from the table TL, and the correction value of the small ink droplet corresponding to the supply pressure P. AS is specified from the table TS. Then, the recording head 24 is controlled so that the number of large ink droplets ejected per unit area is the number of times (NL + AL), or the number of small ink droplets ejected per unit area is the number of times (NS + AS). Accordingly, the correction value AL and the correction value AS increase as the supply pressure P to the recording head 24 decreases, and the rate at which the correction value AL increases with respect to the decrease in the supply pressure P indicates the rate at which the correction value AS increases. The correction value AL and the correction value AS (as a result, the number of large ink droplet ejections (NL + AL) and the number of small ink droplet ejections (NS + AS)) are adjusted so as to exceed the values.

  For example, referring to the cyan (C) ink (nozzle row 34C) in FIG. 8, the control unit 62 refers to the table TH, and the cumulative ejection amount S1 of the nozzle row 34C stored in the first storage unit 64. After detecting (specifying) the supply pressure P1 from the (operation history H), the correction value AL1 of the large ink droplet corresponding to the supply pressure P1 is specified with reference to the table TL, and the supply pressure P1 with reference to the table TS. The correction value AS1 of the small ink droplet corresponding to is specified. Accordingly, the recording head 24 is controlled so that the number of ejections per unit area is the number of times (NL + AL1) for large ink drops and the number of times (NS + AS1) for small ink drops. The other ink colors (nozzle row 34) are similarly corrected. That is, the control unit 62 detects (specifies) the ink supply pressure P for each nozzle row 34 according to the operation history H, and controls (corrects) the number of ink ejections for each ink drop weight according to the supply pressure P. ) That is, the control unit 62 also functions as a detection unit that detects the supply pressure P. As can be understood from FIG. 5, since the ejection weight W of the small ink droplets hardly changes even when the supply pressure P varies, only the number of large ink droplet ejections NL is corrected according to the supply pressure P. A configuration in which the number of small ink droplet ejections NS is not corrected may also be employed.

  The correction of the number of ink droplet ejections described above can be executed at an arbitrary timing. That is, it may be executed periodically (for example, every predetermined number of printing cycles) during the operation time of the printing apparatus 100, or every time the printing operation is completed (that is, for one recording paper 200). It may be executed each time printing is completed, or may be executed every time the carriage 12 on which the recording head 24 is mounted reciprocates once.

  In the first embodiment described above, the number of ink droplet ejections is corrected in accordance with the ink supply pressure P supplied to the recording head 24. For example, the ink in the ink cartridge 22 decreases and the supply pressure P decreases. It is possible to suppress fluctuations in the ink ejection amount (maintain the ejection amount to a target value) even when the ink drops. In addition, since correction is performed for each ink drop weight, it is possible to make corrections that match the change rate of the ejection weight W, which differs depending on the ink drop weight, as compared with a configuration in which correction is made based only on the supply pressure P. It is.

  As a configuration for suppressing fluctuations in the ink ejection amount due to fluctuations in the ink supply pressure P, for example, the drive signal COM supplied to each piezoelectric element 54 is corrected (for example, the potential of the drive signal COM). A configuration in which the ink ejection amount is adjusted by changing the fluctuation width and the pulse width can be assumed. However, if the drive signal COM itself can be corrected, the electrical configuration of the printing apparatus 100 becomes complicated. According to the first embodiment, the amount of ink ejected per unit area is changed by correcting the number of ink droplet ejections, so that correction of the drive signal COM is unnecessary. Therefore, there is an advantage that the configuration of the printing apparatus 100 is simplified.

<B: Second Embodiment>
A second embodiment of the present invention will be described below. In addition, about the element in which an effect | action and a function are equivalent to 1st Embodiment in each structure illustrated below, the detailed description of each is abbreviate | omitted suitably using the code | symbol referred by the above description.

  In the first embodiment, the number of ejections NL of large ink droplets before correction and the number of ejections NS of small ink droplets before correction are constant regardless of the ink color. In the second embodiment, the number of ejections of large ink droplets and the number of ejections of small ink droplets are different for each ink color (each nozzle row 34).

  FIG. 9 is a block diagram including an electrical configuration of the printing apparatus 100 according to the second embodiment. As shown in FIG. 9, the recording head 24 of the second embodiment further includes a second storage unit 44 that stores a color ID (ejection information) for each ink color (nozzle row 34) and each ink weight. The second storage unit 44 is composed of a nonvolatile memory such as an EEPROM or a flash ROM.

  FIG. 10 is a diagram illustrating the configuration of the color ID (ejection information) stored in the second storage unit 44. The color ID is information that defines the number N of ink droplet ejections, and is set for each ink weight and each ink color (nozzle row 34). Specifically, the color ID is calculated based on the actual ink ejection amount measured for each nozzle row 34 before shipment from the factory, and stored in the second storage unit 44. For example, if the designed ejection amount by ejecting a large number of large ink droplets from the nozzle row 34C is 20.0 ng while the actual ejection amount is 19.0 ng, 95 (= (19.0 ÷ 20.0) × 100) Is set as the color ID of the nozzle row 34C. Based on the color ID, the control unit 62 specifies the number N of ejections of each ink droplet (large ink droplet and small ink droplet) per unit area for each nozzle row 34. For example, for the large cyan (C) ink droplet of FIG. 10, since the color ID is 95, the ejection amount is 5% less than the design value, so the control unit 62 increases the number N of ejections per unit area by 5%. .

With reference to FIG. 11, correction of the number of ink ejections performed by the control unit 62 of the second embodiment will be described. First, the control unit 62 refers to the color ID in the second storage unit 44 and determines the number of ink ejections N (NL_C, NS_C, NL_M, NS_M, NL_Y, NS_Y for each ink weight and each ink color (nozzle row 34). , NL_K, NS_K). Similarly to the first embodiment, the control unit 62 detects (specifies) the supply pressure P from the operation history H (cumulative injection amount S) for each nozzle row 34, and then the large ink corresponding to the supply pressure P. The droplet correction value AL is specified from the table TL, and the small ink droplet correction value AS corresponding to the supply pressure P is specified from the table TS. Then, the number of injections (NL_C, NS_C, NL_M, NS_M, NL_Y, NS_Y, NL_K, NS_K) is corrected by the corresponding correction value A (AL, AS).
Hereinafter, the cyan (C) ink (nozzle row 34C) in FIG. 11 will be described in detail. The control unit 62 refers to the color ID, and the number of ejections per unit area of cyan (C) large ink droplets is the number NLC, and the number of ejections per unit area of cyan (C) small ink droplets is the number of times. Identify NSC. Further, the control unit 62 refers to the table TH and specifies that the supply pressure P corresponding to the operation history H (cumulative ejection amount S) of cyan (C) ink (nozzle row 34C) is the pressure P1 ( To detect. The correction value A corresponding to the supply pressure P1 is specified as the correction value AL1 from the table TL for the large ink droplet, and is specified as the correction value AS1 from the table TS for the small ink droplet. Based on the values specified as described above (NLC, NSC, AL1, AS1), the control unit 62 determines the number of cyan (C) large ink droplets ejected per unit area as the number of times (NLC + AL1). The recording head 24 is controlled so that the number of small ink droplets of cyan (C) is the number of times (NSC + AS1). That is, the ejection number N defined for each ink color by the color ID is corrected by the control unit 62 for each ink ejection weight W (large ink droplet or small ink droplet) according to the supply pressure P of each ink.

  FIG. 12 is a graph showing the relationship between the ink ejection amount and the color difference. The color difference is a value indicating a difference (distance in the color space) with respect to the ink color (reference color) in a state where the change in the ink ejection amount has not occurred ("change in ejection amount" in FIG. 12) = 0. As shown in FIG. 12, the color difference increases with a change (increase or decrease) in the ink ejection amount. Therefore, when a variation occurs in the ejection amount per unit area of each color ink in the printing apparatus 100 that forms an image using a plurality of colors of ink, there is a color difference between the target image and the actually formed image. It will occur.

  According to the configuration of the second embodiment, by controlling the number of ejections of ink droplets for each ink color (for each nozzle row 34) based on the color ID, the per unit area between the ink colors (between the nozzle rows 34). Variation in ink ejection amount is reduced. Therefore, it is possible to form a high-quality image with little color difference with respect to the reference color. Further, in addition to fluctuations in the ink ejection amount due to changes in the supply pressure P over time (changes due to an increase in the cumulative ejection amount S), errors in the ink ejection amount in the initial stage (when the printing apparatus 100 is manufactured) are also compensated. .

<C: Third Embodiment>
FIG. 13 is a block diagram including an electrical configuration of the printing apparatus 100 according to the third embodiment. As illustrated in FIG. 13, the printing apparatus 100 according to the third embodiment has a configuration in which a pressure adjustment valve 46 is added to each ink cartridge 22. Each pressure adjustment valve 46 is disposed in the ink supply path 26 from each ink cartridge 22 to the recording head 24 to adjust the ink supply pressure P to the recording head 24. The pressure adjustment valve 46 includes, for example, a damper that reduces the supply pressure P with a spring. Moreover, the 1st memory | storage part 64 of 3rd Embodiment memorize | stores the elapsed time t from reference | standard time. The reference time is, for example, the manufacturing time of the printing apparatus 100 (an arbitrary time during manufacturing).

  FIG. 14 is a graph showing the relationship between the elapsed time t and the supply pressure P. Since the pressure adjustment function (decompression function) decreases due to the deterioration of the pressure adjustment valve 46 with time, the ink supply pressure P to the recording head 24 increases as the elapsed time t increases. The first storage unit 64 stores a table Tt. The table Tt is a table that associates each numerical value (t1, t2,...) Of the elapsed time t with each numerical value (P1, P2,...) Of the supply pressure P. The correlation between the elapsed time t and the supply pressure P in the table Tt is statistically or experimentally determined in advance so that the supply pressure P increases as the elapsed time t increases. Since the relationship between the elapsed time t and the supply pressure P can be different for each ink color (for each nozzle row 34), the table Tt can be provided for each ink color.

  The control unit 62 of the third embodiment detects the supply pressure P according to the elapsed time t (that is, the degree of deterioration with time of the pressure regulating valve 46) by referring to the table Tt stored in the first storage unit 64. (Identify. The operation of controlling the number of injections N according to the supply pressure P is the same as in the first embodiment or the second embodiment. In the third embodiment, since the number of ink ejections is corrected based on the supply pressure P detected (specified) according to the elapsed time t from the reference time, similarly to the first embodiment and the second embodiment. It is possible to reduce fluctuations in the ink ejection amount.

<D: Modification>
Each of the above forms can be variously modified. Specific modifications are exemplified below. Two or more aspects arbitrarily selected from the following examples can be appropriately combined as long as they do not contradict each other.

(1) Modification 1
In each of the above embodiments, the control unit 62 (detection unit) specifies (indirectly detects) the ink supply pressure P according to the operation history H or the elapsed time t, but the printing apparatus 100 uses a pressure sensor as the detection unit. In addition, the ink supply pressure P may be directly detected by the pressure sensor. The pressure detected by the pressure sensor is not limited to the pressure at the ink supply port of the recording head 24 (the end of the supply path 26 on the recording head 24 side). For example, the pressure in the supply path 26 or the pressure in the ink cartridge 22 may be detected as the supply pressure P and used for the above correction.

(2) Modification 2
In the second embodiment, the color ID is stored in the second storage unit 44 of the recording head 24, but the color ID may be stored in the first storage unit 64 of the control device 102. Further, although the correction value A corresponding to the supply pressure P is added to the number of ejections specified by the color ID to correct the number of ink droplet ejections, the color ID itself is changed according to the supply pressure P to change the ink droplets. The number of injections may be corrected.

(3) Modification 3
In each of the above embodiments, an off-carriage method in which the ink cartridge 22 is not mounted on the carriage 12 is employed. However, an on-carriage method in which the ink cartridge 22 is mounted on the carriage 12 may be employed.

(4) Modification 4
In each of the above embodiments, the printing apparatus 100 configured to eject two types of ink droplets (large ink droplets and small ink droplets) has been described. However, the printing device 100 has three or more types of ink droplets (for example, , Large ink droplets, medium ink droplets, and small ink droplets).

(5) Modification 5
In each of the above embodiments, both the operation history H or the elapsed time t and the table T (TH, TL, TS, Tt) are stored in the first storage unit 64. However, the element that stores the operation history H or the elapsed time t is stored. Also, a configuration in which the elements for storing the table T (TH, TL, TS, Tt) are separate storage circuits may be employed. Further, the operation history H, the elapsed time t, and the table T (TH, TL, TS, Tt) may be stored in the first storage unit 44.

(6) Modification 6
In each of the above embodiments, the table T (TH, TL, TS, Tt) is used to detect (specify) the supply pressure P according to the operation history H (elapsed time t). However, the operation history H (elapsed time t) is used. The method for detecting (specifying) the supply pressure P is changed as appropriate. For example, the control unit 62 supplies the supply pressure P by substituting the operation history H (elapsed time t) in the first storage unit 64 into an arithmetic expression that defines the relationship between the operation history H (elapsed time t) and the supply pressure P. Can also be calculated. However, in the configuration for calculating the supply pressure P, the load on the control unit 62 can be excessive. From the viewpoint of reducing the load on the control unit 62, the table T (TH, TL, TS, Tt as in each of the above embodiments). ) Is preferable.

(7) Modification 7
In each of the above embodiments, the supply pressure P is detected (specified) based on the operation history H or the elapsed time t. However, the supply pressure P may be detected (specified) based on both the operation history H and the elapsed time t. According to the above configuration, since the number of ink ejections is corrected based on the influence of both the decrease in the supply pressure P due to ink consumption and the increase in the supply pressure P due to the deterioration of the pressure regulating valve 46 over time, the ejection amount Fluctuations are further reduced.

(8) Modification 8
In each of the above embodiments, the serial type printing apparatus 100 that reciprocates the carriage 12 on which the recording head 24 is mounted is exemplified. However, a plurality of ejection units U (nozzles 56) are provided so as to face the entire width direction of the recording paper 200. The present invention can also be applied to a line-type printing apparatus 100 in which are arranged. In the line-type printing apparatus 100, the recording head 24 is fixed, and an image is recorded on the recording paper 200 by ejecting ink droplets from each nozzle 56 while the recording paper 200 is conveyed. As can be understood from the above description, the movable / fixed state of the recording head 24 (each ejection unit U) itself is not a problem in the present invention.

(9) Modification 9
The element (pressure generating element) that changes the pressure in the pressure chamber 52 is not limited to the piezoelectric element 54. For example, a vibrating body such as an electrostatic actuator can be used. Further, the pressure generating element is not limited to an element that gives mechanical vibration to the pressure chamber 52. For example, a heating element (heater) that changes the pressure in the pressure chamber 52 by generating bubbles by heating the pressure chamber 52 can be used as the pressure generating element. That is, the pressure generating element is included as an element for changing the pressure in the pressure chamber 52, and the method for changing the pressure (piezo method / thermal method) and the configuration are not required.

(10) Modification 10
The printing apparatus 100 of each of the above forms can be employed in various devices such as a plotter, a facsimile machine, and a copier. However, the application of the liquid ejecting apparatus of the present invention is not limited to image printing. For example, a liquid ejecting apparatus that ejects a solution of each color material is used as a manufacturing apparatus that forms a color filter of a liquid crystal display device. In addition, a liquid ejecting apparatus that ejects a liquid conductive material is used as an electrode manufacturing apparatus that forms electrodes of a display device such as an organic EL (Electroluminescence) display device or a field emission display (FED). The A liquid ejecting apparatus that ejects a bioorganic solution is used as a chip manufacturing apparatus for manufacturing a biochemical element (biochip). Then, an object (landing target) that is a target of liquid ejection differs depending on the application of the liquid ejecting apparatus. Specifically, the landing target of the printing apparatus 100 described above is the recording paper 200. However, when the liquid ejecting apparatus is used for manufacturing a display device, for example, a substrate constituting the display device corresponds to the landing target.

DESCRIPTION OF SYMBOLS 100 ... Printing apparatus, 102 ... Control apparatus, 104 ... Print processing part, 12 ... Carriage, 14 ... Movement mechanism, 16 ... Conveyance mechanism, 22 (22K, 22Y, 22M, 22C) ... Ink cartridge , 24... Recording head, 26... Supply path, 32... Discharge surface, 34 (34K, 34Y, 34M, 34C). ... pressure regulating valve, 52 ... pressure chamber, 54 ... piezoelectric element, 56 ... nozzle, 62 ... control unit, 64 ... first storage unit.

Claims (8)

A liquid ejecting apparatus including a liquid ejecting head that ejects liquid supplied from a liquid storage unit as droplets onto a landing target,
A detection unit that detects a pressure of the liquid in a supply path of the liquid to the liquid ejecting head or the liquid storage unit;
A liquid ejecting apparatus comprising: a control unit that corrects the number of times of ejecting the droplet with respect to the unit area of the landing target according to the detected pressure. A storage unit that stores injection information that defines the number of injections;
The liquid ejecting apparatus according to claim 1, wherein the control unit corrects the number of ejections specified by the ejection information according to the pressure. The liquid ejecting head can eject the droplets having different weights,
The injection information defines the number of injections for each weight,
The liquid ejecting apparatus according to claim 2, wherein the control unit corrects the number of ejections defined by the ejection information for each weight according to the pressure. The liquid ejecting apparatus according to claim 3, wherein the ejection information defines the number of ejections for each color of the liquid. The storage unit stores an operation history of the liquid jet head,
The liquid ejecting apparatus according to claim 2, wherein the detection unit detects the pressure according to the operation history. The storage unit stores an elapsed time from a reference time,
The liquid ejecting apparatus according to claim 2, wherein the detection unit detects the pressure according to the elapsed time. The liquid ejecting apparatus according to claim 1, wherein the detection unit is a pressure sensor that detects a pressure of the liquid in the supply path or the liquid storage unit. In a liquid ejecting apparatus including a liquid ejecting head that ejects liquid supplied from a liquid storage unit as droplets onto a landing target,
Detecting the pressure of the liquid in the liquid supply path to the liquid ejecting head or the liquid storage unit, and correcting the number of times of ejecting the droplet with respect to the unit area of the landing target according to the detected pressure Control method of liquid ejecting apparatus.

Images