JP2006168194A - Inkjet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED To prevent defective printing by determining non-ejection at an early stage.
When non-discharge detection is performed by dot count and there is a nozzle determined to be non-discharge, non-discharge detection is performed after a recovery operation performed immediately after. As a result, when it is determined that there is no discharge, the corresponding nozzle is determined to be non-discharge.
[Selection] Figure 1

Description

  The present invention relates to an ink jet recording apparatus that performs recording on a recording medium by discharging ink.

  For the non-ejection detection of an ink jet recording apparatus, configurations such as an optical type, an electrostatic type, an acoustic method (vibration detection method), and a scanner method have been proposed and put into practical use. In addition, as a non-ejection detection method performed in an ink jet recording apparatus that ejects ink and performs recording, the recording head for ejecting ink performs empty ejection that is not used for recording, and the recording head at that time A configuration for determining non-ejection based on the temperature change is also known (for example, Patent Document 1).

On the other hand, with regard to the timing of undischarge detection, a method performed at power-on, a method performed every dot count, a method performed at the start of printing, a method performed every fixed time, a method selectively performed by the user, and these A combination of these has been proposed. When the purpose of non-ejection detection is to detect non-ejection due to disconnection of the inkjet head and to complement it, a method is used to detect that each head has performed a certain amount of printing by dot count. Is often used. Although a method of performing dot count for each heater (nozzle) and detecting discharge failure by the dot count value can be considered, if this method is used with a long head with a large number of nozzles, a considerable amount of memory is allocated to the main body. Because it is necessary, it is not very common. If supplementation is performed for non-ejection nozzles, the nozzles used for complementation will be used more frequently and cause problems in the service life, so it goes without saying that it is better not to supplement for uncertain non-ejections as much as possible. No. Therefore, it is necessary to perform non-discharge detection and determine whether or not the nozzle detected as non-discharge is temporarily non-discharge. In order to solve such a problem, a sequence in which the detection results of a plurality of past times are stored, and the nozzle is determined to be non-ejection only when the results are continuously matched and determined to be non-ejection. Can be considered.
JP 05-293968 A

  When dot count is used as a trigger for undischarge detection, if the dot count is set to a small amount and frequently detected, the printing speed is remarkably hindered because printing is stopped frequently. Also, the disconnection of the heater / wiring caused by printing occurs after printing a certain number of dots, and it is not necessary to frequently detect undischarge. However, since it is necessary to determine when non-ejection occurs as described above, when the dot count interval is long, complementation is not performed until it is determined. As a result, the period during which deterioration of image quality cannot be prevented becomes longer. In addition, it is possible to perform recovery such as cleaning when non-ejection is detected, and then perform non-ejection detection again. However, when such a configuration is used, wasteful ink is consumed during recovery. There are problems such as taking.

  In order to solve the above-described problems, the non-ejection detection after cleaning is performed at the time of cleaning immediately after the occurrence of non-ejection. As a result, it is possible to avoid a situation where non-ejection is not supplemented over a long period of time. Further, in addition to the detection of non-discharge of the dot count, the cleaning time can be shortened without performing unnecessary detection at the time of cleaning as compared with the case where the non-discharge detection is performed every time during cleaning.

  According to the configuration of the present invention, non-discharge information can be determined without wastefully using ink as compared with the conventional case, and printing can be prevented from being performed without discharge over a long period of time. Further, even when temporary non-ejection occurs, there is no wasteful consumption of ink due to cleaning or the like.

Example 1
FIG. 10 shows the appearance of the printer used in the present invention. The recording apparatus used here is a so-called serial scan type recording apparatus, and forms an operation image by scanning the recording head in a direction (main operation direction) perpendicular to the feeding direction of the recording medium. First, an outline of the operation during printing will be described. First, a recording medium is conveyed by a paper feed roller 6 driven by a paper feed motor 5 through a gear. The carriage motor 3 is scanned in the direction orthogonal to the paper feed by the carriage motor 3 to print a fixed bandwidth, feed the paper, and print according to the next bandwidth. However, in the case of such serial scan printing, paper feed in one scan may not be performed if necessary, and paper feed may be performed after performing a plurality of scan prints. There has also been realized a method of printing the drawn data, feeding the paper around 1 / n band, and printing again to complete an image by a plurality of printing scans and paper feeding. In this embodiment, the carriage belt 4 is used to transmit the driving force from the carriage motor 3 to the carriage unit 2, but other driving methods such as a lead screw may be used instead of the carriage belt. The fed recording medium is guided between the paper feeding roller 6 and the pressure roller to the printing portion. At the time of printing, since the cap is applied to the recording head in the normal resting state, the cap is first opened and the carriage is set in a scan-movable state so that in the case of a serial printer, scanning in the main operation direction can be performed. Thereafter, when data for one scan is accumulated in the buffer, the carriage unit 2 is scanned by the carriage motor 3 to perform printing.

  As the water-soluble organic solvent used in the ink of the present invention, any water-soluble organic solvent that has been used in conventionally known inks can be used. Specifically, alkyl having 1 to 5 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, and n-pentanol. Alcohols; Amides such as dimethylformamide and dimethylacetamide; Ketones or ketoalcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene Oxyethylene or oxypropylene addition polymers such as glycol, polyethylene glycol, polypropylene glycol; ethylene glycol, propylene group Alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms, such as coal, trimethylene glycol, butylene glycol, 1,2,6-hexanetriol, hexylene glycol; thiodiglycol; glycerin; ethylene glycol monomethyl (or Lower alkyl ethers of polyhydric alcohols such as ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether; triethylene glycol dimethyl (or ethyl) ether, tetraethylene glycol dimethyl (or ethyl) Lower dialkyl ethers of polyhydric alcohols such as ether; sulfolane, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like. The content of the water-soluble organic solvent as described above is generally in the range of 1 to 49%, preferably 2 to 30% by weight with respect to the total weight of the ink. The water-soluble organic solvents as described above can be used alone or as a mixture, but the most preferable liquid-medium composition in the case of having a medium is at least one water-soluble high-boiling organic solvent such as diethylene glycol, triethylene. It contains a polyhydric alcohol such as glycol or glycerin. If necessary, metal salts such as magnesium nitrate, calcium nitrate, and barium nitrate may be used to improve printing quality.

  FIG. 11 shows the data flow of the printer used in this embodiment. In FIG. 11, reference numeral 101 denotes a programmable peripheral interface (hereinafter referred to as PPI), which receives a command signal (command) and a recording information signal sent from a host computer (not shown) and transfers them to the MPU 102, as well as the console 106. And a signal from the home position sensor 107 for detecting that the carriage is at the home position. An MPU (microprocessing unit) 102 controls each part in the ink jet printer apparatus according to a control program stored in the control ROM 105. Reference numeral 103 denotes a RAM that stores received signals or is used as a work area for the MPU 102 and temporarily stores various data. A font generation ROM 104 stores pattern information such as characters and records corresponding to the code information, and outputs various pattern information corresponding to the input code information. Reference numeral 130 or 121 denotes a print buffer for storing data expanded by the ROM 104 or the like, and has a capacity of m rows. Reference numeral 105 denotes a control ROM in which processing procedures executed by the MPU 2 are stored. Each of these units is controlled by the MPU 102 via an address bus 117 and a data bus 118, respectively.

  Reference numeral 108 denotes a carriage motor that reciprocally scans the carriage on which the recording head 112 is mounted. Reference numeral 110 denotes a paper feed motor for transporting a recording material such as paper in a direction perpendicular to the moving direction of the carriage, and 113 denotes an ink discharge port (not shown) of a recording head 112 described later by driving a cap member. ), And a purge motor for operating the wiper to wipe off the ink on the head face by operating the wiper to block the ink discharge port from the outside air and prevent the nozzle from drying. 115 is a motor driver for driving the carriage motor 108, 116 is a motor driver for driving the paper feed motor 110, and 114 is a motor driver for driving the capping motor 113. The console 116 is provided with a keyboard switch and a display lamp. The home position sensor 107 is provided in the vicinity of the home position of the carriage, and detects that the carriage on which the recording head 112 is mounted has reached the home position.

  A sheet sensor 109 detects the presence or absence of a recording material such as recording paper, that is, whether or not the recording material is supplied to the recording unit. Reference numeral 112 denotes an ink jet recording head that discharges ink droplets by causing a change in state due to film boiling in ink using thermal energy. The recording head 112 has m (for example, 64) discharge ports (not shown). ), M discharge heaters (not shown) corresponding to each discharge port are provided. Reference numeral 111 denotes a driver for driving the discharge heater of the recording head 112 in accordance with the recording information signal. A power supply unit 124 supplies power to each of the above units, and includes an AC adapter and a battery as a drive power supply device.

  In the above configuration, the MPU 2 is connected to a host device such as a computer via the PPI 101, and processing procedures for commands and recording information signals sent from the host device and programs stored in the control ROM 106. The recording operation is controlled based on the recording information stored in the RAM 106.

  In a normal recording apparatus conventionally used in the field where the present invention is used, when print data is transmitted from a host 100 that transmits recording data via a parallel port, an infrared port, a network, or the like, Type of media to be recorded at the beginning (special media such as plain paper, OHP, glossy paper, and special media such as transfer film, cardboard, banner paper, etc.), media size (A4, A4 letter, A3, B4)・ B5 or envelopes and postcards), print quality (draft, high quality, medium quality, specific color emphasis, monochrome / color type, etc.), paper feed cassette (ASF, manual feed, bin 1, bin 2, etc.), object A memory that is usually called ROM is sent by sending a command describing whether or not there is automatic discrimination and accepting the command in the main unit Determine the area (memory 1 122) implantation amount, the printing direction of the ink per print pass number and unit area at the time of multi-pass printing based on the data of the store of various in such perform recording. In some cases, information such as whether or not to apply the treatment liquid is transmitted as a command. According to these pieces of information, the recording device reads the data necessary for recording from the ROM described above, and performs recording according to those data. In addition to the above, the data read from these ROMs is used for recording each pass. There are mask types used for recording, recording head drive conditions (for example, applied pulse shape and application time), droplet size, paper feed conditions, carriage speed, and the like.

  FIG. 12 shows the configuration of ink supply. The ink is supplied from the ink tank 39 and passes through the tube 45, and is sent to the head 9 via the joint. The ink buffer 41 is an ink that overflows from the inside of the tank as the air in the tank mainly expands in the supply path. Has a function of temporarily holding

  The ink tank is molded by injection, blow, or the like using a resin such as PP or PE, and is assembled using techniques such as ultrasonic welding, thermal welding, adhesion, and fitting. Inside the tank, there is a type in which the exterior functions as an ink chamber as it is, a type having a bag filled with ink inside, a type in which a porous material is inserted inside to hold ink and simultaneously generate negative pressure, etc. . Further, when the tank is provided with a negative pressure mechanism, negative pressure may be generated by supporting the bag portion inside the tank in the expansion direction by a spring mechanism or the like provided inside or outside the bag.

  At the time of printing, since the cap is applied to the recording head in the normal resting state, the cap is first opened and the carriage is set in a scan movable state so that scanning can be performed in the main operation direction in the case of a serial printer. Thereafter, when data for one scan is accumulated in the buffer, the carriage motor 2 is scanned by the carriage motor 3 to perform printing.

  So-called pre-printing before printing is performed before the cap is opened and printing is started. Usually, this preliminary discharge is performed with a uniform number of shots or with a number of shots determined by the standing time. The number of shots may be set for each color.

  The preliminary ejection during printing may be performed for only the nozzles that are not used or may be performed for all the nozzles including the used nozzles. In addition, a mechanism that reduces preliminary discharge based on the frequency of use can be provided for the nozzles in use. In some cases, the preliminary discharge is interrupted and moved to a position where the preliminary discharge can be performed, and all the heads are collectively or for each head.However, in order to improve the printing speed, the preliminary discharge is simultaneously performed while performing the printing operation. Sometimes it is done. Examples of sequences accompanying such printing are shown in FIGS. 7, 8, and 9. FIG.

  FIG. 3 shows an external view of the wiper used in this example, FIG. 4 shows an external view of the head used in this example, and FIG. 5 shows a cross-sectional view of the head used in this example. The cross-sectional view of FIG. 5 is a cross-sectional view of the head shown in FIG. 4 along the A-A ′ and B-B ′ planes. The width of the nozzle wiper 20 of Bk. Shown in FIG. 3 is made slightly narrower than the width K of the chip of FIG. This is because, in order to avoid contact with the print medium, each color chip is slightly recessed from the TAB surface as shown in FIG. 5, and the wiper enters and wipes the recessed surface. For the same reason, the nozzle wiper for the color chip, which is a single unit of the three colors, is set to be equal to or smaller than the width of the three color chips. The wiper shown in FIG. 3 is attached to a wiper holder 27 (not shown) using a wiper fixing bracket (not shown). This is done by fitting with the pin. The wipers 20, 21, and 22 are driven by the purge motor 113 in the G direction shown in FIGS. 3 and 4 to wipe the orifice and the TAB surface. When the wiping operation is completed, the carriage is retracted outside the wiping area, and the wiper is driven in the reverse direction to return to the position where wiping is started.

  As shown in FIG. 4, 640 nozzles are arranged at a density of about 245 nozzle per cm in Bk., And 1280 nozzles are arranged at a density of about 490 nozzle per cm for each color in the color head. In FIG. 5, ink advances and is supplied in the direction of H from the supply port 23 and is guided to the ink liquid chamber 24 on the filter in the head. Thereafter, the process proceeds in the direction of arrow J in the figure, and after dust and the like mixed by the filter 25 is filtered, it is guided to the ink liquid chamber 26 under the filter and guided to the nozzle for discharging the ink formed on the lower surface of the orifice plate. It is burned. FIG. 6 shows an enlarged view of the nozzle portion of the head shown in FIG. 4 used in the present invention. The ink liquid chamber is formed by a heater board on which an orifice plate 31, a liquid chamber forming member 34, and a heater are mounted. The ink stored in this portion generates bubbles by the heating of the heater 33 and is pushed out of the orifice plate as the bubbles expand, and becomes spherical droplets by the interfacial tension with the air and flies toward the recording member.

  The recording apparatus of the present invention is configured assuming a so-called A4 size recording material. When the total number of dots printed is full on an A4 recording medium, the color is 1.26 × 108 dots. The maximum number of dots is printed. Similarly, the Bk head has a maximum number of printable dots of 3.17 × 107 dots. Regarding the dot count at the time of wiping, the number of dots counted by the dot counter in the recording device is stored in the main body (memory 122, etc.), and it is determined whether or not a predetermined value has been reached after printing is completed. ing. In this embodiment, the determination of whether or not wiping is performed is configured to be performed at the end of each page. However, in the case of a plotter or large format printer having a large print area, it is configured to determine whether or not to perform wiping after each print scan. Is also possible. In addition, the ink mist adhering to the face surface as well as the dot count may vary depending on the print duty.Therefore, the number of dots may be increased or decreased by adding a coefficient calculated based on the duty to the number of dots. Is possible.

  The control of the present invention will be described with reference to FIG. After the recovery sequence S11 is performed by a trigger such as a timer or dot count, it is determined whether or not the recovery sequence is immediately after the dot count discharge failure determination sequence S48 is performed by S44. If the recovery is not performed immediately after the non-discharge detection, the process is terminated without performing the non-discharge detection sequence S46, but if the detection is performed immediately after the non-discharge detection, it is determined whether or not there is a non-discharge in the previous non-discharge detection sequence. To do. When there is a discharge failure nozzle, discharge failure determination is further performed by the discharge failure determination sequence S46 after recovery. If the nozzle determined to be non-discharged in the non-discharge detection S48 based on dot count is determined to be non-discharge again in the non-discharge determination sequence S46 after recovery, the nozzle is determined to be non-discharged in the S47 non-discharge nozzle determination sequence Is confirmed. In addition, it is possible to determine undischarge nozzles by referring to the past non-discharge information at the time of determination and referring to the information. When the non-discharge nozzle is determined, it is possible to complement the nozzle set to be non-discharge based on the non-discharge information by the main body, the driver, or the like. As a complementing method, there are a method of complementing with adjacent nozzles, a method of complementing with a nozzle that prints the same raster as the non-ejection nozzle during multi-pass printing, and any method may be used.

  As a comparison, FIG. 17 illustrates a sequence for performing cleaning for recovery when non-ejection is detected. When non-discharge is detected in the non-discharge determination sequence S48, a recovery sequence S11 is performed. After the recovery operation is completed, the undischarge determination sequence S46 after recovery is performed again. Here, when it is determined that the same nozzle as the non-discharge determination sequence S48 is non-discharge, the non-discharge nozzle determination sequence of S47 is performed, and the non-discharge nozzle is determined as in the case of the embodiment. When such a configuration is used, there is an adverse effect that a large amount of ink is consumed when non-ejection occurs due to indefinite elements such as face wetting and dust. According to the configuration of the present embodiment, there is no such problem, and there is an advantage that an undischarge nozzle can be determined earlier than when relying only on a relatively long dot count.

  FIG. 14 shows a determination sequence used in the recording apparatus, and FIG. 15 shows a detection sequence. In the determination sequence of FIG. 14, it is determined whether or not the detection is performed in the order of the heads K, C, M, and Y according to the steps of S31, S32, S33, and S36. When the head to be determined (for example, K) is selected, it is determined whether or not the corresponding head has increased the dot count. If the dot count is increased, the detection sequence of S35 is executed. FIG. 15 shows an outline of the detection sequence. In S39, 40, 41, the Nth nozzle is selected, and a discharge pulse is applied to perform discharge. A delay S43 is performed while the droplet travels the distance from the head to the sensor after ejection. Measure the output with the detector. This completes the measurement for one nozzle. After that, the measurement is performed until the maximum number of nozzles A is sequentially defined.

  FIG. 2 shows an example of the hardware configuration of the invention. The light emitted from the light emitting element 58 in FIG. 2A is incident on the light receiving element 59 placed facing the light emitting element. Each element is arranged so as to sandwich a chip arranged in a head shape, and in this embodiment, the optical axis and the nozzle row are arranged in parallel. In addition to such a configuration, a configuration in which detection is performed while the head is moved by placing the optical axis obliquely with respect to the nozzle row does not contradict the spirit of the present embodiment. As shown in FIG. 2A, when the ink droplet 61 does not exist on the optical axis 60, the light emitted from the light emitting element reaches the light receiving element. A schematic diagram at the time of detection is shown in FIG. The ink 61 ejected from the head 9 blocks the optical axis between the light emitting element and the light receiving element, and the signal level from the light receiving element decreases as shown in the output curve of FIG. An example in which a normal output is obtained is shown in FIG. The time is plotted on the horizontal axis and the analog output is plotted on the vertical axis. In the output curve 67, the output keeps a constant level when there is no obstacle on the optical axis. When ejection is performed from the head and ink droplets reach the vicinity of the optical axis, ink droplets appear on the optical axis after ejection and the received light level is lowered, and the analog output is also lowered. When the ink droplet passes through the optical axis, the output is restored, and when the ink droplet completely passes, the output returns to the original level.

  In an inkjet recording device, drying / thickening of ink at the ejection opening when not in use Generally, in an inkjet recording device, ink dot size reduction, change in ejection direction, change in ink density due to increased viscosity, which is called ejection failure due to drying, etc. This may cause density unevenness due to. Therefore, when there is non-use time in the recording head, and when there is non-use time for unspecified / specific nozzles in the head, discharge that is not related to recording called pre-discharge before printing is performed, A technique for preventing discharge failure has been introduced. If these discharge failures occur when undischarge is detected as in this embodiment, the detection accuracy is reduced. FIG. 2A shows a normal output when there is no ejection failure, while FIG. 2-B shows an output curve when an ejection failure occurs. The output curve 68 indicated by the solid line is when the defect is mild, and the output curve 69 indicated by the broken line is when the discharge defect is remarkable. When a threshold is set at a certain output level and the time during which the output exceeding the output level is held is measured, t1 is obtained when the defect is minor, but t2 is obtained when the output level is further lowered, and the difference in level is increased. In such a case, it is difficult to determine whether the level is lowered due to a true ejection failure or an initial ejection failure. Therefore, in this embodiment, in addition to the time t3 from when the pulse for ejection is applied until the droplet is detected, a delay of time t4 at which initial ejection failure is a concern is added and detected at a time interval of t5. Determine the signal. For example, as shown in FIG. 2C, in the case of a head whose output has decreased due to the occurrence of a slight ejection failure, the normal head output level varies as t1 and t2 in normal measurement, so t6 It cannot be detected whether this nozzle, which is the output time, is defective in ejection. Here, when the detection method of the present embodiment is used, it can be determined that the output level of the nozzle shown in FIG. A schematic diagram of the cross section of the optical axis in such a case is shown in FIG. In this drawing, R is the diameter of the optical axis, r is the diameter of the droplet, and p is the period of each droplet. The ink droplet 61 is continuously ejected at a predetermined ejection cycle and traverses the optical axis cross section as shown in the schematic diagram. The ink 61 ejected for detection in FIG. 2 reaches the ink receiver A62 and the ink receiver B63 as waste ink 65, is discharged from the ink discharge port 64, and is guided and absorbed on a waste ink absorber 66 (not shown). If it is difficult to absorb the ink discharged to the absorbing means such as a waste ink absorbing pair structurally, the ink may be collected in an ink reservoir / container having an appropriate volume.

(Example 2)
Next, a second embodiment of the present invention will be described.

  In the configuration of the first embodiment, when non-ejection is detected, if the remaining time until cleaning is less than a predetermined ratio (for example, if the cleaning interval is 5 days, 4 days or more have passed) It is also possible to configure such that cleaning is performed when spitting is detected.

Sequence used in the present invention. The structural example of the detection part of this invention. The structural example of the wiper used in the Example. FIG. 2 is an external view of a head used in an example. Sectional drawing of the head used in the Example. The enlarged view of a nozzle part and an orifice part. Recovery sequence before printing. Print sequence. Recovery sequence after printing. 1 is an external view of a recording apparatus used in Example 1. FIG. 2 is a data flow diagram of the recording apparatus used in Example 1. FIG. 1 is an overview of an ink supply path of the present embodiment. The output signal example of this invention. The example of the undischarge determination sequence used in the Example. The example of the undischarge detection sequence used in the Example. The schematic diagram of an ink / optical axis in the detection part used in the Example. Conventional sequence.

Explanation of symbols

1 Purge unit
2 Carriage unit
3 Carriage motor
4 Carriage belt
5 Feed motor
6 Paper feed roller
7 Pressure roller
8 Eject roller
9 Recording head
10 shaft
Nozzle wiper for 20 Black
Nozzle wiper for 21 Color
22 Full wiper
27 Wiper holder
28 Wiper fixing bracket
32 nozzles
33 Heater
35 Black head
36 Cyan head
37 Magenta head
38 Yellow head
49 Black tank
50 Cyan tank
51 Magenta tank
52 Yellow tank
57 paper
58 Light emitting element
59 Photo detector
60 optical axis
100 hosts
102 CPU
103 RAM
104 ROM for print data
108 Carriage motor
110 Conveyor motor
111 Head driver
112 Recording head
121 Print buffer

Claims (3)

  An ejection tank that includes a head that ejects ink, an ink tank that retains the ink, and a supply unit that supplies ink to the head from the tank. When it is detected that a certain nozzle is non-ejection, non-ejection is determined at the next cleaning, and only when the non-ejection is determined again, the nozzle is judged as non-ejection. Non-ejection determination mechanism and recording apparatus using the determination mechanism.   The non-ejection determining mechanism according to claim 1, further comprising: a counting unit that counts the ejected dots for each head, and determining whether the ejection is good or not when the counting unit reaches a certain dot. A recording apparatus using the determination mechanism.   The non-ejection determination mechanism according to claim 2 and a recording apparatus using the determination mechanism according to claim 2, wherein the next cleaning is performed by a timer.

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