JP2005169860A - Inkjet recording method and inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method that uniforms colors of color mixing portions formed by superposing a plurality of colors of ink drops between during forward scanning and during backward scanning and an inkjet recording device that is inexpensive and small. <P>SOLUTION: A recording head discharging inks of different colors is provided in a manner that makes it scan forward and backward with respect to a recording medium, ink drops Y and M of two colors to be given on top of the other to the same positions of the recording medium are given in different order for the forward and backward scanning of the recording head. At this point, the quantity of the ink of one ink drop Y of the two ink drops Y and M to be given to the same position of the recording medium is varied between the forward scanning (scanning in the X1 direction) and the backward scanning (scanning in the X2 direction). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention allows the recording head to reciprocate in the direction intersecting the conveying direction of the recording medium such as paper, resin sheet, cloth, etc., and ejects droplets both when the recording head moves forward and backward. The present invention relates to an ink jet recording apparatus and an ink jet recording method.

  An ink jet recording apparatus employs a so-called non-impact recording system in which recording is performed on a recording medium such as paper by discharging micro droplets (ink) from micro discharge ports of nozzles arranged in a recording head. Thus, there are various advantages that recording on various recording media and high-speed recording can be performed without generating noise during the recording operation. For this reason, at present, it is widely adopted as an image output device of information processing equipment such as a copying machine, a word processor, and a computer, and communication equipment such as a facsimile. As a representative example of this ink jet recording apparatus, there is an apparatus that uses thermal energy of an electrothermal conversion element for generating ink droplet ejection energy.

  In recent years, the inkjet recording system has been used for various purposes, and therefore, in addition to high-speed recording and high image quality, further cost reduction and downsizing are required. As an ink jet recording apparatus that satisfies this requirement, a recording head is mounted on a carriage that transports a recording medium in a certain direction and moves along a direction intersecting the transport direction of the recording medium. A so-called serial scan type ink jet recording apparatus that performs a recording operation by reciprocating scanning is known.

  FIG. 13 is an explanatory cross-sectional view showing the structure of a plurality of ink ejection nozzles formed on a recording head used in this serial scan type ink jet recording apparatus. In FIG. 13, a liquid supply port 219 is formed in the substrate 218, and ink is supplied thereto. Further, the upper surface of the substrate is covered with a nozzle forming member 223, and a row of ink flow paths is formed in contact with the ink supply port 219. The electrothermal transducer 220 is formed on the upper surface of the substrate at the bottom surface of each ink flow path. In addition, discharge ports 224 are formed corresponding to the respective electrothermal transducers.

  FIG. 14 is a partially cutaway perspective view showing the configuration of a general color inkjet recording head. The actual recording head is generally four colors of black, cyan, magenta, and yellow. However, in order to simplify the description, FIG. 14 shows an ink that ejects two colors of ink. The description will be made according to the recording head that discharges the two colors of ink.

Here, a case will be described where two colors of ink are ejected, yellow and magenta.
There are two liquid supply ports 219, to which yellow and magenta inks are respectively supplied. Then, an ink jet recording head (hereinafter also simply referred to as a recording head) reciprocally scans the recording medium together with a carriage that holds the ink, and ink droplets of magenta and yellow are landed on the recording medium in both forward scanning and backward scanning. By repeating this, an image is formed. Now, assuming that the two color ink droplets ejected in the forward scan land on the recording medium in the order of magenta and yellow, in the backward scan, each ink is applied to the recording medium in the order of yellow and magenta. Land.

  For example, as shown in FIG. 2, in a recording head in which yellow is arranged on the left side and magenta is arranged on the right side, when the carriage scans in the forward scanning direction (X1 direction), both ink droplets are recorded in the order of magenta and yellow. Landing at the same dot formation position on the medium, the color of the formed dot is red.

  FIG. 3 is a cross-sectional view schematically showing the landing state of ink droplets at this time. As shown in the figure, in the recording medium, the magenta ink droplet that has landed first penetrates the recording medium and spreads on the surface and inside. Next, the landed yellow ink droplets go under the magenta. For this reason, when viewed from the surface of the recording medium, the hue of the formed dots is red, which is a mixed color of magenta and yellow.

On the other hand, when the recording head moves in the backward scanning direction (X2 direction) together with the carriage, the ink droplets land on the same dot formation position of the recording medium in the order of yellow and magenta, and the surface of the recording medium of the formed dots The hue seen from the side is red.
However, at the time of this backward scanning, dots are formed in a state where magenta ink droplets that have landed later are buried under yellow that has landed first, so red, which is a mixed color of both inks, is shown in FIG. Unlike the dots formed during the forward movement shown, yellow is the dominant hue red.

  As described above, when forming mixed color dots by overlapping a plurality of colors of ink (here, magenta and yellow) in bidirectional recording, even if the combination of the inks forming the mixed color dots is the same, Dots with different colors in dynamic scanning and reverse scanning are alternately formed in units of areas recorded in one scan, causing color unevenness in the image and degrading image quality. . Such a problem becomes particularly noticeable when a color image is formed by one-pass recording suitable for high-speed recording.

  Therefore, in order to solve such a problem, Patent Document 1 discloses a configuration in which the heads of the respective colors are arranged symmetrically so that the order in which the inks of the respective colors are landed is the same during forward scanning and backward scanning. ing.

Further, Patent Document 2 discloses a configuration in which, as a technique for solving color unevenness in reciprocal recording, the amount of ink that is applied later in the forward traveling direction in the reciprocating scanning is reduced in both the forward and backward directions. Yes. In other words, in the case of printing in the order of cyan (C) and magenta (M) in the main scanning in the forward direction, the discharge amount of magenta (M) applied later is reduced in both the forward and return paths. Disclosure. In this case, since the printing order is reversed in the return path, the magenta ejection amount applied first in the return path is smaller than cyan.
In addition, the dots recorded in the order of the forward scan and the dots of the backward scan are alternately recorded along the main scanning direction in the area recorded in one scan, so that the color difference Patent Document 3 discloses a configuration that makes the image less noticeable.

Japanese Patent Laid-Open No. 08-295034 Japanese Patent Laid-Open No. 11-207999 Japanese Patent Laid-Open No. 05-167838

  However, in the configuration disclosed in Patent Document 1, since the ejection port arrays are arranged so as to be symmetric with respect to the scanning direction of the head, for example, in the case of a three-color head, there are three colors. However, the ejection port array for five colors is required, the configuration of the recording head is increased, and the entire recording apparatus using the recording head is also increased in size.

  For this reason, in a recording device with a relatively high price range, there is not much problem in adopting the above configuration, but the configuration is not suitable for a recording device with a low price range. Accordingly, in the current situation, the target type recording head as described above is hardly used for a low-cost printer head such as a bundle machine.

  However, there is a demand for current inkjet recording apparatuses that are used for various purposes, which can realize high image quality even at a low price and have a small configuration.

  Further, in the above-mentioned Patent Document 2, it is necessary to control the recording dots, specifically the discharge amount, in both the forward scanning and the backward scanning, and the control becomes complicated.

  Further, in Patent Document 3, the ratio of the ink landed in the forward scan to the paper surface and the ratio of the ink landed in the backward scan to the paper surface differ depending on the penetration mechanism of the ink with respect to the paper. A difference in color appears in the unit of recording width.

  In the present invention, when a plurality of color ink droplets are applied in the same place on a recording medium, even if the color order of the ink droplets is different between the backward scan and the backward scan, the mixed color portion formed in both the scans An object of the present invention is to provide an ink jet recording method and an ink jet recording method that can form a high-quality image without causing a difference in color and that can be configured inexpensively and in a small size.

In order to solve the above-described problems of the prior art, the present invention has the following configuration.
That is, according to the first aspect of the present invention, a recording head for ejecting different colors of ink is provided so as to be capable of reciprocating scanning with respect to a recording medium, and ink droplets of a plurality of colors to be applied in the same place on the recording medium are provided. An ink jet recording method in which the recording head forward scanning and reverse scanning are applied in different orders, and at least one color among a plurality of color ink droplets to be applied in the same place on the recording medium The ink amount of the ink droplet is made different between forward scanning and backward scanning.

  According to a second aspect of the present invention, a recording head for ejecting inks of different colors is provided so as to be capable of reciprocating scanning with respect to a recording medium, and ink droplets of a plurality of colors to be applied in the same place on the recording medium. An inkjet recording apparatus in which the recording head is applied in different orders for forward scanning and backward scanning, and at least one of ink droplets of a plurality of colors to be applied in the same place on the recording medium Is provided with control means for controlling the ink amount of the ink droplets to differ between forward scanning and backward scanning.

  In the present invention, when ink droplets of a plurality of colors are applied in the same place on the recording medium, the application order of the ink droplets is different between forward scanning and backward scanning. Due to the difference in the order of application, there is no color difference in the overlapping portion of the ink droplets of a plurality of colors, and the occurrence of color unevenness can be prevented. Therefore, it is possible to form a high-quality image using a small and inexpensive recording head without using a conventionally proposed large symmetric recording head.

  Embodiments according to the present invention will be described below with reference to the drawings. In the ink jet recording apparatus and the ink jet recording method according to the following embodiments, a carriage that holds a recording head that discharges ink performs reciprocal scanning along the main scanning direction, and the recording head in each of forward scanning and backward scanning. In other words, a so-called serial scan method is employed in which a recording operation is performed while ejecting ink from the ink.

First, the recording head cartridge in the present embodiment will be described with reference to FIGS.
As shown in FIG. 10, the recording head cartridge H1000 in this embodiment includes an ink tank H1900 that stores ink, and a recording head unit H1001 that discharges ink droplets supplied from the ink tank H1900 from nozzles according to recording information. The recording head unit H1001 is detachably mounted on a carriage (not shown). The recording head unit H1001 shown here integrally holds four types of recording heads. The ink tank H1900 stores four ink tanks H1901 to H1904 that store different inks (here, four colors of black, yellow, cyan, and magenta) for each recording head of the recording head unit H1001. The ink tanks H1901 to H1904 are detachable from the recording heads. Accordingly, the recording head unit H1001 can eject inks of different colors supplied from the respective ink tanks attached thereto from the respective recording heads.

  Further, as shown in the exploded perspective view of FIG. 11, the recording head unit H1001 includes a tank holder H2000, a first recording element substrate H1101, a second recording element substrate H1100, a first plate H1200, and an electric wiring tape H1300. , An electrical contact substrate H2200, a second plate H1400, an ink supply member H1500, a flow path forming member H1600, a joint rubber H2300, a filter H1700, a seal rubber H1800, and the like.

  The first recording element substrate H1101 and the second recording element substrate H1100 have a plurality of recording elements for ejecting ink to one side of the Si substrate and electric wiring such as Al for supplying power to each recording element. A plurality of ink flow paths and a plurality of ejection openings corresponding to the recording element are formed by a photolithography technique.

Further, the first recording element substrate H1101 and the second recording element substrate H1100 are bonded and fixed to the first plate H1200. Here, an ink supply for supplying ink to the second recording element substrate H1100 is provided. A mouth H1201 is formed.
Further, a second plate H1400 having an opening is bonded and fixed to the first plate H1200, and this second plate H1400 is electrically connected to the electric wiring tape H1300 and the recording element substrate H1100. An electric contact substrate H2200 is held. The electrical contact substrate H2200 applies an electrical signal for ejecting ink to the first recording element substrate H1101 and the second recording element substrate H1100, and the first recording element substrate H1101 and the second recording element substrate H1100 An electrical wiring corresponding to the second recording element substrate H1100 and an external signal input terminal H1301 positioned at the end of the electrical wiring for receiving an electrical signal from the main body are positioned and fixed on the back side of the ink supply member H1500. Yes.

FIG. 12 is a partially cutaway perspective view showing the first recording element substrate H1101 and the second recording element substrate H1100 provided in the ink jet recording head H1001 shown in FIGS. 10 and 11 in an enlarged manner.
Ink is supplied from the ink tank H1900 (H1901 to H1904) to the first recording element substrate H1101 and the second recording element substrate H1100 of the recording head unit H1001. The first recording element substrate H1101 and the second recording element substrate H1100 are provided with a plurality of ejection ports H1100T arranged in a staggered manner on both sides of the ink supply port H1201, and ink liquid is respectively supplied from the ejection ports H1100T. An electrothermal conversion element H1103 that generates thermal energy used for ejection is provided on a substrate made of silicon for each ink flow path H1501.

In the ink jet recording head having the above-described configuration, the ink is held by forming a meniscus in the vicinity of the plurality of ejection openings H1100T. At this time, the electrothermal conversion element H1103 is selectively driven according to image recording information and the like, and the ink on the heat acting surface is rapidly heated and boiled using the generated heat energy. Ink droplets are ejected from the ejection port H1100T through the ink flow path H1501 from the ink supply port H1201 by pressure.
The ink droplets land on a recording medium such as a sheet sent to a position facing the recording head to form a desired image record.

Next, the operation in the first embodiment of the present invention will be described in detail with reference to FIGS.
First, how ink adheres during forward scanning will be described with reference to FIGS.
As shown in FIG. 2, when the recording head Yh that discharges yellow ink on the left side and the recording head Ch that discharges magenta ink on the right side are arranged, the carriage moves in the forward scanning direction (X direction). In this case, the ink droplets land on the same dot formation position on the recording medium in the order of magenta and yellow. As a result, mixed color dots having a red hue when viewed from the surface of the recording medium are formed.

FIG. 3 is a cross-sectional view schematically showing the state of penetration of ink droplets into the recording medium P at this time. As illustrated, in the recording medium P, first, magenta ink M permeates and spreads on the surface and inside. Next, the landed yellow ink Y enters under the magenta ink M.
When the dots formed in this way are viewed from the surface of the recording medium, the magenta ink M and the yellow ink Y overlap to form a red mixed color dot, but as described above, the yellow ink Since Y sinks under the magenta ink M, not much yellow ink remains on the surface, and as a result, magenta-dominated red dots are formed.

On the other hand, at the time of backward scanning, the carriage moves in the backward scanning direction (X2 direction) as shown in FIG. 4, and ink droplets land on the same dot formation position on the recording medium in the order of yellow and magenta. As a result, mixed color dots having a red hue when viewed from the surface of the recording medium are formed.
In this backward scanning, as shown in FIG. 1 (b), when the yellow and magenta ink droplets are landed at the same ejection amount as in the forward scanning, the yellow ink Y is opposite to the forward scanning. Since the magenta ink M is landed later, the magenta ink M sinks under the yellow ink Y, and in contrast to the forward scanning, a red dot in which yellow is dominant is formed. The color will be different.

Therefore, in this embodiment, as shown in FIG. 1A, the ink amount of the yellow ink droplet Y hit first is decreased, and the ink amount of the magenta ink droplet M hit later is increased.
By doing this, the amount of yellow ink Y spreading on the surface and inside is reduced, and a large amount remains on the surface of magenta M to be hit next. As a result, magenta is dominant red dots as in the forward scan. Can be formed.

In addition, during forward scanning, as shown in FIG. 1A, since the area where yellow spreads on the surface is small as a whole, magenta-dominated red is formed as in forward scanning. Recording without unevenness in color can be performed.
Here, the ink amount of the yellow ink droplet Y to be landed first is decreased, and the ink amount of the magenta ink droplet M to land later is increased, but the conditions such as the ink density, the ejection amount, and the ink permeability are required. Accordingly, the degree of increase / decrease in the ink amount needs to be set appropriately. For example, it may be possible to reduce only the ink amount of yellow ink droplets or to increase the ink amount of magenta ink droplets, and it is necessary to set the ink amount according to various conditions. .

  The ink amount of the ink droplets ejected from each recording head can be controlled by modulating the pulse width of the drive pulse by a known control unit that applies the drive pulse to the electrothermal conversion element. This control means includes a known recording head drive circuit and a control unit such as a CPU that controls the drive of this drive circuit.

  As a method of applying a drive pulse to the electrothermal conversion element, for example, as shown in FIGS. 5A and 5B, in order to preliminarily heat the ink in the nozzle, the electrothermal conversion element is first relatively A method is known in which a pre-pulse PS1 having a short pulse width t1 (t1 ′) is applied, and then a main pulse PS2 having a relatively long pulse width t3 (t3 ′) is applied via a pause time t2. In the case of adopting, the discharge amount can be controlled as follows.

  That is, as shown in FIG. 5A, if the pre-pulse width t1 for heating in yellow recording in the backward scan is made shorter than that in the forward scan and the main pulse width t3 is made longer than that in the backward scan, The yellow discharge amount can be reduced compared with the forward scanning without changing the total pulse width.

  Further, as shown in FIG. 5B, if the prepulse width t1 ′ for heating during magenta recording is made longer than that during forward scanning and the main pulse width t3 ′ is shortened, the total pulse width is not changed. The discharge amount can be increased.

More specifically, the total pulse width (t1 + t3) shown in FIG. 5A is equal to the total pulse width (t1 ′ + t3 ′) shown in FIG. 5B, and t1 <t1 ′, t3. > T3 ′ is set.
However, with regard to the pause times t2 and t2 ′, there are cases where t2 = t2 ′ and t2 ≠ t2 ′, and the settings of t1 ′, t2 ′, and t3 ′ need to be changed each time depending on the discharge amount to be controlled. It is.
By doing so, it is possible to realize a small recording head at a low cost, and it is also possible to reduce the size of the entire inkjet recording apparatus using the recording head.

  Here, the case of mixing two colors of yellow and magenta has been described. However, in the recording operation using four colors of black, cyan, magenta, and yellow, yellow discharged from the recording head Yh as shown in FIGS. 8 and FIG. 9 and the magenta ink M ejected from the recording head Mh and the cyan ink C ejected from the recording head Ch as shown in FIGS. In this case as well, in this case as well, by increasing or decreasing the discharge amount of each ink according to the scanning direction of the recording head, it always has a constant color in both reciprocating scans. A mixed color portion can be formed.

  In the above-described embodiment, the case where an electrothermal conversion element is used as an ejection energy generating element that generates ejection energy for ejecting ink from the recording head has been described as an example. The present invention is also applicable to a case where a recording head having an electromechanical conversion means such as a piezo is used.

(A) is sectional drawing which shows typically the state in which the red dot was formed without the color unevenness by the reciprocating scanning in embodiment of this invention, (b) formed the red dot by the reciprocating scanning in a prior art example. It is sectional drawing which shows typically the state in which the color nonuniformity has arisen. FIG. 5 is an explanatory plan view showing a relationship between the arrangement of two recording heads that eject yellow and magenta inks and the forward scanning direction. FIG. 10 is a cross-sectional view schematically showing a permeation state of each ink droplet into a recording medium when each ink droplet is landed on the same landing position on the recording medium in the order of magenta and cyan by a conventional recording method. FIG. 6 is an explanatory plan view showing a relationship between the arrangement of two recording heads that discharge yellow and magenta inks and the backward scanning direction. (A) is a diagram showing drive pulses applied to the recording head in the embodiment of the present invention, (a) is a drive pulse width when yellow ink droplets are ejected during backward scanning, and (b) is a restoration pulse. Drive pulse widths in the case of ejecting magenta ink droplets during scanning are shown. FIG. 4 is an explanatory plan view showing a relationship between the arrangement of two recording heads that discharge yellow and cyan inks and the forward scanning direction. FIG. 6 is an explanatory plan view showing a relationship between the arrangement of two recording heads that discharge yellow and cyan inks and the backward scanning direction. FIG. 6 is an explanatory plan view illustrating a relationship between an arrangement of two recording heads that eject magenta and cyan inks and a forward scanning direction. FIG. 6 is an explanatory plan view showing a relationship between the arrangement of two recording heads that eject magenta and cyan inks and the backward scanning direction. 2A and 2B are perspective views illustrating a recording head cartridge according to an embodiment of the present invention, in which FIG. 1A illustrates a state in which the recording head unit and the ink tank are combined, and FIG. 2B illustrates a state in which the recording head unit and the ink tank are separated. Each is shown. It is a disassembled perspective view which shows the state which decomposed | disassembled the recording head shown in FIG. FIG. 12 is a partially cutaway perspective view showing an enlarged view of a first recording element substrate and a second recording element substrate provided in the ink jet recording head shown in FIGS. 10 and 11. FIG. 4 is an explanatory cross-sectional view illustrating a structure of a plurality of ink ejection nozzles formed on a recording head. FIG. 2 is a partially cutaway perspective view showing a configuration of a general color inkjet recording head.

Explanation of symbols

H1100T Discharge port H1900 Ink tank H1103 Electrothermal conversion element H1104 Orifice plate H1200 First plate H1201 Ink supply port H1300 Electrical wiring tape
H1301 External signal input terminal H1400 Second plate H1500 Ink supply member Yh Recording head ejecting yellow ink droplet Ch Recording head ejecting yellow ink droplet Mh Recording head ejecting yellow ink droplet PS1 Prepulse PS2 Main pulse t1 Pre-pulse width t2 Main pulse width P Recording medium X1 Forward scan direction X2 Reverse scan direction

Claims (12)

A recording head for ejecting ink of different colors is provided so as to be capable of reciprocating scanning with respect to the recording medium, and ink droplets of a plurality of colors to be applied in an overlapping manner on the same location of the recording medium are transferred to the forward scanning and backward scanning of the recording head. In the ink jet recording method, which is applied in a different order,
Ink-jet recording characterized in that the ink amount of at least one color ink droplet among the plurality of color ink droplets to be applied in the same place on the recording medium is different between forward scanning and backward scanning. Method.   2. The ink jet recording method according to claim 1, wherein the ink droplets of a plurality of colors to be applied in the same place on the recording medium are ink droplets of two different colors.   In either one of the forward scan and the backward scan of the recording head, the ink amount of at least one color ink droplet among the plurality of color ink droplets to be applied in the same place on the recording medium is set to the other ink. 3. The ink jet recording method according to claim 1, wherein the ink amount is made different from the ink amount of the droplet.   The recording head includes a plurality of nozzles for ejecting ink droplets, and generates thermal energy by applying a driving pulse to an electrothermal conversion element provided in the nozzle, and bubbles are formed in the ink by the thermal energy. 4. The ink jet recording method according to claim 1, wherein the ink droplets are ejected by generating ink.   The ink jet recording method according to claim 4, wherein the ink amount of the ink droplets ejected from the recording head is controlled by changing a pulse width of the driving pulse. The drive pulse applied to the recording head generates bubbles in the ink heated by the pre-pulse and the pre-pulse for generating the thermal energy from the electro-thermal conversion element to the extent that no ink droplet is ejected from the nozzle. And a main pulse for generating heat energy for discharging ink droplets from the electrothermal conversion element,
6. The ink jet recording method according to claim 5, wherein the ink amount of the ink droplet is controlled by changing a pulse width of at least one of the pre-pulse and the main pulse.   7. The ink amount of the ink droplet is changed by changing a pulse width of the pre-pulse and the main pulse, and changing an application timing of the pulse of the main pulse to the electrothermal conversion element. Inkjet recording method. A recording head for ejecting ink of different colors is provided so as to be capable of reciprocating scanning with respect to the recording medium, and ink droplets of a plurality of colors to be applied in an overlapping manner on the same location of the recording medium are transferred to the forward scanning and backward scanning of the recording head. In the inkjet recording apparatus that is applied in a different order,
Control means for controlling the amount of ink droplets ejected from the recording head;
The control means is characterized in that the ink amount of at least one color ink droplet among a plurality of color ink droplets to be applied in the same place on the recording medium is differentiated between forward scanning and backward scanning. Inkjet recording device.   The control means includes at least one ink droplet ink among a plurality of color ink droplets to be applied in the same place on the recording medium in either one of the forward scan and the backward scan of the recording head. 9. The ink jet recording apparatus according to claim 8, wherein the amount is different from the ink amount of other ink droplets.   The recording head includes a plurality of nozzles for ejecting ink droplets, and generates thermal energy by applying a driving pulse to an electrothermal conversion element provided in the nozzle, and bubbles are formed in the ink by the thermal energy. The ink jet recording apparatus according to claim 8, wherein the ink droplets are ejected by generating ink.   11. The control unit according to claim 10, wherein the control unit controls the ink amount of ink droplets ejected from the recording head by generating the drive pulse and changing a pulse width of the drive pulse. Inkjet recording device. The control means generates a pre-pulse for generating thermal energy from the electrothermal transducer so as not to discharge an ink droplet from the nozzle, and generates bubbles in the ink heated by the pre-pulse to discharge the ink droplet. Applying a main pulse for generating thermal energy from the electrothermal transducer as a drive pulse to the electrothermal transducer,
The inkjet recording apparatus according to claim 11, wherein the ink amount of the ink droplet is changed by changing a pulse width of at least one of the pre-pulse and the main pulse.

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