JP2009190282A - Liquid ejection inspecting method, liquid ejection inspecting apparatus, and printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejection inspecting method whereby an inspection accuracy can be improved by monitoring that a noise level is at a proper value and reducing a rate of wrong detection, and to provide a liquid ejection inspecting apparatus, and a printer. <P>SOLUTION: At the time of inspecting the presence or absence of ejection of ink droplets from an ink nozzle on the basis of a current change amount at a head cap 63 by making the ink droplets ejected from the ink nozzle of a printing head 14 in a state that a potential difference is generated between the printing head 14 where a plurality of nozzles for ejecting the ink droplets are formed and the head cap 63 disposed oppositely to the printing head 14 via a gap, the current change amount in a state of refraining ejection of the ink droplets is measured for each nozzle array by a plurality of the number of times, an average value of the measured values is calculated, and whether or not the average value is not larger than a preliminarily set target value is determined. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid discharge inspection method, a liquid discharge inspection apparatus, and a liquid discharge inspection apparatus that inspects whether or not liquid droplets are discharged from a nozzle based on a current change amount in a liquid receiving portion by discharging liquid droplets from a nozzle of a liquid discharge portion. The present invention relates to a printing apparatus including the same.

2. Description of the Related Art Generally, a printing apparatus such as an ink jet printer is configured to perform printing by ejecting ink droplets from a plurality of nozzles to desired positions by a print head mounted on a carriage that can reciprocate.
In this type of ink jet printer, a method for inspecting whether or not ink droplets are being ejected normally is a liquid ejection inspection in which the presence or absence of ejection is determined by detecting current changes caused by charged ink ejected from nozzles. A method is known (see, for example, Patent Document 1).
JP 2006-264243 A

  In the liquid discharge inspection method as described above, “discharge” or “non-discharge” can be determined based on whether or not the magnitude of the detected current change exceeds a predetermined threshold. Nevertheless, it can be probabilistic that it is determined as “non-ejection” or “discharging” despite non-ejection. In order to reduce the frequency of such false detections, ensure a sufficiently large difference between the signal level of the current change during “ejection” and the signal level of the current change during “non-ejection” (ie, the noise level). It is important to set a threshold value in the meantime, but if the noise level increases due to changes over time or environmental changes (S / N ratio decreases), there is a probability that “non-ejection” is determined as “ejection”. It will rise. If it is determined that “non-ejection” is “ejection”, a non-ejection state is not detected, and normal liquid ejection processing is performed with missing dots.

  It is conceivable that error processing is performed when the noise level exceeds even once by using a threshold value for determining “ejection” and “non-ejection”, but the overall noise level is large enough not to exceed the threshold value. When it becomes, it cannot be detected.

  Accordingly, an object of the present invention is to provide a liquid discharge inspection method, a liquid discharge inspection apparatus, and a printing apparatus capable of monitoring that the noise level is an appropriate value and reducing the false detection rate and improving the inspection accuracy. It is to provide.

A liquid ejection inspection method according to the present invention that can solve the above-described problems is a liquid ejection section in which a plurality of nozzles that eject liquid droplets are formed, and a liquid that is disposed with a gap facing the liquid ejection section. A liquid for inspecting whether or not a liquid droplet is ejected from the nozzle based on the amount of current change in the liquid receiving section by ejecting a liquid droplet from the nozzle in a state where a potential difference is generated between the liquid receiving section and the receiving section. A discharge inspection method,
Measuring a current change amount in a state in which droplets are not discharged a plurality of times, calculating an average value of the measured values, and determining whether the average value is equal to or less than a preset target value; To do.

In addition, the liquid discharge inspection apparatus according to the present invention includes a liquid discharge unit in which a plurality of nozzles for discharging droplets are formed,
A liquid receiving portion that can be disposed with a gap facing the liquid ejection portion;
A detection unit for detecting a current change in the liquid receiving unit,
In a state where a potential difference is generated between the liquid discharge unit and the liquid receiving unit, the droplet is discharged from the nozzle, and the droplet is discharged from the nozzle based on the amount of current change detected by the detection unit. A liquid discharge inspection device for inspecting the presence or absence of
The amount of current change in a state where no droplet is ejected is measured a plurality of times, an average value of the measured values is calculated, and it is determined whether or not the average value is equal to or less than a preset target value. And

  According to the liquid discharge inspection method and the liquid discharge inspection apparatus with this configuration, the current change amount (noise level) in a state where no droplet is discharged is measured a plurality of times, and it is determined whether the average value is equal to or less than the target value. Thus, it is possible to monitor whether or not the noise level is at an appropriate value. When the noise level becomes larger than the target value, it can be predicted that the SN ratio becomes small and the inspection accuracy of the liquid discharge inspection is lowered. It is possible to return the nozzle to a good state and improve the inspection accuracy of the liquid discharge inspection again.

In the liquid ejection inspection method according to the present invention, the liquid ejection section includes a plurality of nozzle rows in which a plurality of the nozzles are arranged in parallel,
It is preferable to measure the amount of current change in a state where droplets are not ejected by using any nozzle included in each nozzle row each time the liquid of each nozzle row is ejected.

Further, in the liquid discharge inspection apparatus according to the present invention, the liquid discharge unit has a plurality of nozzle rows in which a plurality of the nozzles are arranged in parallel,
It is preferable that the amount of change in current in a state where droplets are not ejected is measured using any of the nozzles included in each nozzle row each time liquid is ejected from each nozzle row.

  According to the liquid discharge inspection method and the liquid discharge inspection apparatus having this configuration, since the noise level is measured for each nozzle row among the plurality of nozzles formed in the liquid discharge unit, Easy to calculate noise level. Accordingly, it is possible to appropriately determine whether or not the noise level is equal to or lower than the target value.

Further, a printing apparatus according to the present invention includes the liquid ejection inspection apparatus according to the present invention,
Ink is used as the liquid,
The liquid ejection unit is a print head that ejects ink droplets;
The liquid receiving portion is a head cap that can contact and separate from the print head.

  According to the printing apparatus of this configuration, when performing the ink ejection inspection of the print head, it is possible to monitor whether or not the noise level is appropriate and maintain the inspection accuracy of the ink ejection inspection so as not to decrease. By detecting defects such as missing dots in the print head with high accuracy, it is possible to maintain good print quality.

Hereinafter, examples of embodiments of a liquid discharge inspection method, a liquid discharge inspection apparatus, and a printing apparatus according to the present invention will be described with reference to the drawings.
FIG. 1 is an external perspective view of a roll paper printer that is a printing apparatus according to an embodiment of the present invention. FIG. 2 is an external perspective view of the roll paper printer shown in FIG. 3 is a schematic side view showing the internal configuration of the roll paper printer shown in FIG. 1, and FIG. 4 is a perspective view of the roll paper printer shown in FIG. 1 with the printer case removed.

  The roll paper printer 1 of the present embodiment performs color printing on roll paper by an ink jet method using a plurality of types of color ink liquids, and as shown in FIG. A roll paper cover 3 and an ink cartridge cover 7 are provided on the front surface of the printer so as to be freely opened and closed. A recording paper discharge port 4 having a predetermined width corresponding to the width of the roll paper is formed on the front surface of the printer case 2a. A paper discharge guide 5 protrudes forward below the recording paper discharge port 4, and an opening / closing lever 6 for opening the roll paper cover 3 is disposed on the side of the paper discharge guide 5. A rectangular opening 2b for inserting and removing roll paper is formed below the paper discharge guide 5 and the opening / closing lever 6 in the printer case 2a. The opening 2b is sealed by the roll paper cover 3. .

  When the open / close lever 6 is operated, the roll paper cover 3 is unlocked. When the paper discharge guide 5 is pulled forward after unlocking, as shown in FIG. 2, the roll paper cover 3 is opened until it becomes almost horizontal forward with the lower end as a center. When the roll paper cover 3 is opened, the roll paper storage unit 11 formed inside the printer is opened, and the recording paper transport path from the roll paper storage unit 11 to the recording paper discharge port 4 is opened. The roll paper can be easily replaced from the front. In FIG. 2, the exterior portion of the roll paper cover 3 and the opening / closing lever 6 are not shown.

  As shown in FIG. 3, a roll paper storage unit 11 is formed in the center of the main body frame 10 in the width direction inside the roll paper printer 1. The roll paper storage unit 11 stores the roll paper 12 in a direction along the roll paper width direction in the printer width direction.

  A head unit frame 13 is horizontally attached to the upper end of the main body frame 10 above the roll paper storage unit 11. The head unit frame 13 includes a print head 14 that is an inkjet head, a linear scale 15 and an encoder sensor 16 for detecting the position of the print head 14, a carriage 17 on which the print head 14 and the encoder sensor 16 are mounted, and a carriage 17. A carriage guide shaft 18 for guiding the movement of the printer in the printer width direction is arranged. A carriage transport mechanism including a carriage motor 19 and a timing belt 20 for reciprocating the carriage 17 along the carriage guide shaft 18 is disposed.

  The print head (liquid ejection part) 14 is mounted on the carriage 17 so that the nozzle formation surface 14a for ejecting ink droplets faces downward. The encoder sensor 16 is disposed on the upper end surface 14 b of the print head 14. The carriage guide shaft 18 is stretched horizontally in the printer width direction, and the linear scale 15 is stretched parallel to the carriage guide shaft 18 above the print head 14.

  A platen 21 that extends horizontally in the printer width direction with a certain gap is disposed below the print head 14. The printing position of the print head 14 is defined by the platen 21. A tension guide 22 curved downward is attached to the rear end of the platen 21. The tension guide 22 is biased upward by a spring, and the recording paper 12 a drawn from the roll paper 12 stored in the roll paper storage unit 11 is printed in a state where a predetermined tension is applied by the tension guide 22. It is pulled out along the recording paper conveyance path passing through the position.

  On the rear side of the platen 21, a rear paper feed roller 23 is stretched horizontally in the printer width direction. A rear paper pressing roller 24 having a predetermined width is pressed against the rear paper feeding roller 23 through the recording paper 12a with a predetermined pressing force. A front paper feed roller 25 is disposed at a front end side portion of the platen 21. A front paper pressing roller 26 is pressed against the front paper feeding roller 25 from above via the recording paper 12a. The rear paper feed roller 23 and the front paper feed roller 25 are driven by a paper feed motor 27 mounted on the main body frame 10.

  While the carriage 17 is reciprocatingly moved along the carriage guide shaft 18, printing is performed on the surface of the portion of the recording paper 12 a that is fed from the roll paper 12 and positioned at the printing position by the print head 14 mounted on the carriage 17. Is done. The printing position is controlled based on the detection signal of the encoder sensor 16. After a series of line printing in the width direction of the recording paper 12a is completed, the rear paper feeding roller 23 and the front paper feeding roller 25 are rotationally driven to feed the recording paper 12a by a predetermined pitch. After this, the next line is printed. Thus, the recording paper 12a is printed by the print head 14 while being intermittently sent out at a predetermined pitch. For example, a scissors-type recording paper cutting device 28 is disposed at the recording paper discharge port 4 from which the recording paper 12a after printing is discharged. The recording paper cutting device 28 cuts the recording paper 12a positioned between them in the width direction.

  The platen 21, the tension guide 22, the rear paper feed roller 23, and the front paper feed roller 25 are configured to open and close together with the roll paper cover 3.

  When the ink cartridge cover 7 shown in FIGS. 1 and 2 is opened, the inner cartridge mounting portion 9 (see FIG. 4) is opened, and the ink cartridge 8 can be attached to and detached from the cartridge mounting portion 9. become.

  The ink cartridge 8 contains a plurality of color ink packs in a cartridge case. In the case of the roll paper printer 1 of the present embodiment, the ink cartridge 8 is pulled out by a predetermined distance in front of the cartridge mounting portion 9 in conjunction with the operation of opening the ink cartridge cover 7.

When each ink pack in the ink cartridge 8 is mounted on the cartridge mounting portion 9, the ink supply needle provided on the cartridge mounting portion 9 side is inserted and connected to the ink supply port of the ink pack. An ink channel 31 fixed in the printer case 2 a is connected to the ink supply needle of the cartridge mounting portion 9, and one end of a flexible ink supply tube 33 is connected to the ink channel 31. .
The other end of the ink supply tube 33 is connected to the carriage 17 and communicates with the print head 14 via a damper unit and a back pressure adjustment unit.

  As shown in FIG. 4, the upper position of the cartridge mounting portion 9 that is out of the printing area is a standby position (maintenance area) of the carriage 17 that reciprocates. A head maintenance mechanism 40 that performs a maintenance operation of the print head 14 exposed on the lower surface of the carriage 17 is disposed below the standby position.

  As shown in FIG. 5, the head maintenance mechanism 40 includes a head cap mechanism 60 for sealing the nozzle formation surface of the print head 14, a wiper mechanism 50 for wiping the nozzle formation surface, and a head cap mechanism 60. And an ink suction mechanism 70 for sucking the residual ink.

  The head cap mechanism 60, the wiper mechanism 50, and the ink suction mechanism 70 are driven by a pump motor (not shown) via a power transmission mechanism 80. These parts are attached to a housing 41 that can be attached to and detached from the printer body.

The wiper mechanism 50 and the head cap mechanism 60 are provided side by side in the reciprocating direction of the carriage 17, and the ink suction mechanism 70 is provided on the rear side of the head cap mechanism 60 (right rear side in FIG. 5).
A power transmission mechanism 80 is arranged so that the head cap mechanism 60, the wiper mechanism 50, and the ink suction mechanism 70 can be interlocked.

  The power transmission mechanism 80 is constituted by a gear train composed of a plurality of gears. The head cap mechanism 60 and the wiper mechanism 50 are moved in the direction along the reciprocating direction of the print head 14 and up and down by the driving force from the pump motor and the guide of the housing 41. The ink suction mechanism 70 is operated while moving forward and backward in the direction.

  The ink suction mechanism 70 is a tube pump in which one end of the tube 72 is connected to the head cap mechanism 60 and the other end is connected to the waste ink introducing portion of the ink cartridge 17. When the ink suction mechanism 70 is driven, Ink is sucked from the nozzles of the print head 14 via the head cap mechanism 60 and discharged into the waste ink storage chamber of the ink cartridge 8.

The head cap mechanism 60 includes a slider 64 and a head cap (liquid receiving portion) 63 fixed to the cap holder 62. The slider 64 is formed in a case shape, and is supported by the housing 41 so as to approach or separate from the nozzle formation surface of the print head 14.
A cap holder 62 having a head cap 63 fixed to the tip portion is held in the upper end recess of the slider 64 so as to move forward and backward with respect to the slider 64.

  The wiper mechanism 50 includes a slider 52 and a wiper 51. The slider 52 is formed in a box shape, and a slide portion 53 is supported and guided by a guide portion 44 provided in the housing 41 so as to slide in the same direction as the slider 64 of the head cap mechanism 60. A wiper 51 made of a rubber plate material, which is an elastic material, is embedded in the tip portion of the slider 52.

  The slider 52 can move between a position where the wiper 51 is most retracted inside the head maintenance mechanism 40 (retracted position) and a wiping position where the wiper 51 performs a process of wiping off dirt on the nozzle forming surface. It is like that. The wiping position is such that the tip of the wiper 51 contacts and rubs against the nozzle forming surface of the print head 14. Thereby, the wiper 51 can wipe off foreign matters such as ink adhering to the nozzle formation surface. Depending on the type of ink, the wiper 51 may be formed of soft plastic or the like.

  As shown in FIG. 6, the head cap 63 is formed of a box-shaped rubber having an opening with a size capable of sealing the nozzle forming surface 14 a of the print head 14, and the upper edge is formed with a nozzle. The lip portion 96 can be in close contact with the surface 14a.

  The head cap 63 has a storage recess 94, and a storage material 95 having a multilayer structure for absorbing waste ink is stored in the storage recess 94. The absorption material 95 is held by a pressing member (not shown). The upper surface is a position lower than the tip position of the lip portion 96.

  One end of a tube from the ink suction mechanism 70 is connected to the head cap 63, and the pump motor of the ink suction mechanism 70 is driven while the lip portion 96 is in close contact with the nozzle forming surface 14a. Then, the inside of the head cap 63 is depressurized, and ink is sucked from the ink nozzles of the print head 14 and discharged into the waste ink storage chamber of the ink cartridge 8.

  In addition, a metal shaft 97 as a current inspection detector is erected in the housing recess 94 of the head cap 63, and the metal shaft 97 can be electrically connected to the absorber 95. A lead wire 98 is connected to the lower end of the metal shaft 97, and a signal can be taken out through the lead wire 98.

  In the roll paper printer 1, the print head 14 is cleaned by the head maintenance mechanism 40. This cleaning is performed at a predetermined timing or at the time of a user's operation. The head cap 63 is brought into close contact with the nozzle forming surface 14a of the print head 14, and the inside is sucked by the ink suction mechanism 70 for printing. An ink suction process for sucking thickened ink from the ink nozzles of the head 14 and a wiping process for wiping dirt on the nozzle formation surface 14a of the print head 14 with the wiper 51 are performed.

  Further, in the roll paper printer 1 provided with the head maintenance mechanism 40, a predetermined amount of ink from the ink nozzles of the print head 14 is started before or periodically to form an ink meniscus at the ink nozzles of the print head 14. A flushing process for ejecting ink into the head cap 63 and a capping process for protecting the head cap 63 by closely contacting the nozzle forming surface 14a of the print head 14 are performed after the suspension of printing in order to prevent clogging of the ink nozzles.

  Further, in the roll paper printer 1, the head maintenance mechanism 40 performs an ink ejection test for inspecting whether ink droplets are normally ejected from the plurality of ink nozzles formed on the nozzle formation surface 14 a of the print head 14. . That is, the head maintenance mechanism 40 also has a function of an ink discharge inspection device (liquid discharge inspection device).

Next, an ink ejection inspection method (liquid ejection inspection method) using the head maintenance mechanism 40 will be described with reference to a flowchart shown in FIG. 7 and a detection signal distribution graph shown in FIG.
When the ink ejection inspection is started, the head cap 63 is raised and disposed at a height at which a slight gap is provided with respect to the nozzle formation surface 14a of the print head 14, and the head cap 63 is The print head 14 moves upward (step S01).
In this state, a gap of a predetermined dimension A is formed between the nozzle formation surface 14 a of the print head 14 and the tip of the lip portion 96 of the head cap 63, and the nozzle formation surface 14 a of the print head 14 and the head cap 63 The gap with the upper surface of the absorbent 95 is set to a predetermined dimension B that is narrow enough to satisfactorily perform ink ejection inspection (see FIG. 6).

In this state, a voltage is applied between the print head 14 and the head cap 63 with a predetermined potential difference (step S02).
Then, with the voltage applied, the process proceeds to an ink discharge inspection execution process (step S03).

In the ink discharge inspection, ink droplets (droplets) charged in order for each ink nozzle are discharged from a plurality of ink nozzles formed on the nozzle formation surface 14a of the print head 14 (step S03). For example, on the nozzle forming surface 14a, 12 nozzle rows in which 45 ink nozzles are arranged in a row are formed, and a total of 540 ink nozzles are formed.
In this way, a current change signal generated when the charged ink lands on the absorber 95 is taken out from the current inspection metal shaft 97 via the lead wire 98, and each ink nozzle is based on the current change. It is possible to inspect the ejection state of the ink droplets from.

Then, ink is ejected for each row of ink nozzles, and when ejection of one row is completed, the current change in the non-ejection state is detected using the last ink nozzle of that row, and the noise level is measured (step S04). Ink nozzles used for noise level measurement may be any nozzle included in the nozzle row.
Next, it is determined whether or not all nozzles have been inspected (step S05). If there is still a nozzle row that has not been inspected (step S05: No), the inspection row is shifted (step S06). Discharge. That is, after the ejection inspection of one row of ink nozzles, the noise level is measured using one ink nozzle as many as the number of nozzle rows while shifting the nozzle row.

In order to determine whether or not ink droplets are ejected, it is determined based on whether or not the magnitude of the detected current change signal is greater than a predetermined threshold. Depending on what criteria this threshold is set for, the false detection rate will change.
FIG. 8 shows a signal distribution of current change and its change. The horizontal axis of the graph of FIG. 8 indicates the magnitude (absolute value) ΔV of the current change signal, N is a detection signal (that is, noise) during non-ejection, S is a detection signal during ejection, and μ (N ) Is the average value of N, μ (S) is the average value of S, σ (N) is the standard deviation of N, and σ (S) is the standard deviation of S.
In FIG. 8A, the S / N ratio is comparatively large and the state of the print head 14 is good, such as shortly after the print head 14 is cleaned. FIG. 8B shows an example in which the SN ratio is reduced due to an annular change, a use state, or the like.

  The threshold is set to an intermediate value based on, for example, σ (S) and σ (N), and a value smaller than the threshold by a predetermined width (for example, 5.85σ (N)) The target value. As shown in FIG. 8A, if the noise level is less than or equal to this target value, the noise level is sufficiently small with respect to the threshold, and a false detection rate (false positive) that determines “non-ejection” as “ejection”. Rate) can be set to a desired probability (1 / 750,000) or less. On the other hand, as shown in FIG. 8B, when the noise level exceeds the target value, the noise level is close to the threshold value, and the false positive rate has a desired probability (1 / 750,000). It will be bigger.

  Therefore, as shown in FIG. 7, when the discharge inspection of all the nozzles is completed (step S05: Yes), an average value is calculated from the noise level (number of samples 12) measured for each nozzle row (step S07), and the average is calculated. It is determined whether or not the value is less than or equal to the target value (step S08). Here, if the average value of the noise level is equal to or less than the target value as shown in FIG. 8A (step S08: Yes), the head cap 63 is lowered and the ink ejection inspection is normally completed (step S09). If the average value of the noise level exceeds the target value as shown in FIG. 8B (step S08: No), the head cap 63 is raised to cap the nozzle forming surface 14a, and the cleaning operation (abnormal process) is performed. It performs (step S10). As a result, the nozzles of the print head 14 can be returned to a good state, and the detection accuracy of the ink ejection test can be made good again.

  As described above, according to the ink ejection inspection method and the ink ejection inspection device of the present embodiment, the current change amount (noise level) in a state where ink droplets are not ejected is measured a plurality of times, and the average value is the target value. By determining whether or not it is below, it is possible to monitor whether or not the noise level is at an appropriate value. When the noise level is higher than the target value, it can be predicted that the SN ratio is reduced and the inspection accuracy of the ink ejection inspection is lowered. Therefore, the ink nozzle is improved by performing the cleaning process of the print head 14. In this state, the inspection accuracy of the ink ejection inspection can be improved again, and the false positive rate can always be maintained below the desired probability.

  In addition, every time the ejection test is performed on each nozzle row, the noise level is measured for each nozzle row using any of the ink nozzles included in the nozzle row, so that an average noise level in the print head 14 is calculated. Cheap. Accordingly, it is possible to appropriately determine whether or not the noise level is equal to or lower than the target value.

When the roll paper printer 1 equipped with the ink discharge inspection device (head maintenance mechanism 40) that performs the ink discharge inspection method performs the ink discharge inspection of the print head 14, does the noise level have an appropriate value? By monitoring whether or not, a decrease in inspection accuracy is detected, and the false positive rate at which “non-ejection” is judged as “ejection” can be reliably maintained below a desired probability. Therefore, it is possible to improve the detection accuracy by reducing the false detection rate of the ink ejection inspection, and it is possible to maintain a good print quality by accurately detecting defects such as missing dots of the print head 14.
The frequency at which the ink ejection inspection is performed is set as appropriate. As an example of the high frequency, it can be performed each time printing is performed on a piece of recording paper 12a, that is, every time the recording paper cutting device 28 is operated. According to this, good print quality can always be maintained.

  The liquid discharge inspection method and the liquid discharge inspection apparatus according to the present invention include a color material discharge head and an organic EL display used for manufacturing a color filter such as a liquid crystal display, including the ink jet printer exemplified in the above embodiment. , Electrode material discharge heads used for electrode formation such as FED (surface emitting display), liquid organic discharge heads used for biochip manufacturing liquid discharge devices using liquid discharge heads, samples as precision pipettes, etc. It can also be applied to a discharge device or the like.

1 is an external perspective view of a roll paper printer that is a printing apparatus according to an embodiment of the present invention. FIG. 2 is an external perspective view showing a state in which a roll paper cover of the roll paper printer shown in FIG. 1 is opened. FIG. 2 is a schematic side view showing an internal configuration of the roll paper printer shown in FIG. 1. FIG. 2 is a perspective view showing a state where a printer case is removed from the roll paper printer shown in FIG. 1. It is a perspective view of a head maintenance mechanism. FIG. 4 is a cross-sectional view of a part of the head maintenance mechanism. 3 is a flowchart of an ink discharge inspection method. It is a graph which shows distribution of the signal of the current change at the time of an ink discharge test | inspection, and its change.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Roll paper printer (printing apparatus), 14 ... Print head (liquid discharge part), 14a ... Nozzle formation surface, 40 ... Head maintenance mechanism (liquid discharge test | inspection apparatus), 63 ... Head cap (liquid receiving part), 97 ... Metal shaft (detector).

Claims (5)

In a state in which a potential difference is generated between the liquid discharge unit in which a plurality of nozzles for discharging liquid droplets are formed and the liquid receiving unit disposed with a gap facing the liquid discharge unit, A liquid discharge inspection method for inspecting whether or not a liquid droplet is discharged from the nozzle based on a current change amount in the liquid receiving portion by discharging a liquid droplet,
Measuring a current change amount in a state in which droplets are not discharged a plurality of times, calculating an average value of the measured values, and determining whether the average value is equal to or less than a preset target value; Liquid discharge inspection method. The liquid discharge inspection method according to claim 1,
The liquid ejection unit has a plurality of nozzle rows in which a plurality of the nozzles are arranged in parallel,
A liquid discharge inspection method, characterized in that each time a liquid is discharged from each nozzle row, a current change amount in a state where droplets are not discharged is measured using any nozzle included in the nozzle row. A liquid discharge section in which a plurality of nozzles for discharging droplets are formed;
A liquid receiving portion that can be disposed with a gap facing the liquid ejection portion;
A detection unit for detecting a current change in the liquid receiving unit,
In a state where a potential difference is generated between the liquid discharge unit and the liquid receiving unit, the droplet is discharged from the nozzle, and the droplet is discharged from the nozzle based on the amount of current change detected by the detection unit. A liquid discharge inspection device for inspecting the presence or absence of
The amount of current change in a state where no droplet is ejected is measured a plurality of times, an average value of the measured values is calculated, and it is determined whether or not the average value is equal to or less than a preset target value. Liquid discharge inspection device. In the liquid discharge inspection apparatus according to claim 3,
The liquid ejection unit has a plurality of nozzle rows in which a plurality of the nozzles are arranged in parallel,
Each time a liquid is ejected from each nozzle row, a current change amount in a state where no liquid droplet is ejected is measured using any nozzle included in the nozzle row. . A liquid ejection inspection device according to claim 3 or 4,
Ink is used as the liquid,
The liquid ejection unit is a print head that ejects ink droplets;
The printing apparatus, wherein the liquid receiving portion is a head cap that can contact and separate from the print head.

Images