JP2009066805A - Liquid ejecting apparatus and control method thereof - Google Patents

Abstract

The print quality is further improved.
An ink droplet mass determination device is provided for determining the mass of an ejected ink droplet by ejecting a charged ink droplet from a print head to an inspection area and detecting a change in voltage generated at that time. Whenever the threshold value Nref is exceeded, an ink droplet is ejected from the nozzle, and the ink droplet mass determination device determines the ink droplet mass M (S130). When printing is instructed, the mass correction coefficient is based on the ink droplet mass M In addition to setting Km, an execution drive voltage V is set by the set mass correction coefficient Km (S140 to S190), a head drive waveform is generated by the set execution drive voltage V, and printing processing is executed (S200, S210). Thereby, an ink droplet of an appropriate mass can be ejected from the nozzle, and the print quality can be further improved.
[Selection] Figure 5

Description

  The present invention relates to a liquid ejection apparatus that ejects liquid onto a target to form dots and a control method therefor.

Conventionally, the liquid ejection device is configured as a color inkjet printer that performs printing by ejecting ink droplets from nozzle rows of each color formed on the print head, and print parameters based on head identification information that represents the characteristics of the print head unit. Has been proposed, and printing is performed in accordance with the set print parameters (see, for example, Patent Document 1). In this apparatus, head drive information, ink discharge amount information, and the like are included as head identification information, and the actuator of the print head is driven based on these information, regardless of the influence during manufacture of the print head. In addition, it is said that ink droplet ejection can be accurately controlled and color printing can be performed cleanly.
JP 2000-71440 A

  As described above, accurately controlling the ejection of ink droplets from the nozzle is extremely important for high-quality printing by forming accurate dots on a sheet of paper. A more accurate understanding is required.

  The main object of the liquid ejection apparatus and the control method thereof according to the present invention is to make it possible to form a high-quality dot on a target by more accurately grasping the ejection characteristics of droplets from a nozzle.

  The liquid ejection apparatus and the control method thereof according to the present invention employ the following means in order to achieve the main object described above.

The liquid ejection device of the present invention is
A liquid ejection apparatus that ejects liquid to a target to form dots,
A head on which a nozzle is formed;
Liquid receiving means for receiving the liquid discharged from the nozzle;
A potential difference applying means for applying a potential difference to the head or the liquid receiving means;
Electrical change detection means for detecting a change in electrical state of the head or the liquid receiving means;
The head is driven and controlled so that liquid is ejected as droplets from the nozzle in a state where a potential difference is applied to the head or the liquid receiving unit by the potential difference applying unit at a predetermined timing and the electrical change detecting unit. Determining the mass of the droplets ejected from the nozzle based on the magnitude of the change in the electrical state detected by, and driving the head based on the determination result when instructed to form dots on the target And a control means for controlling the drive of the head so that droplets are ejected from the nozzle with the adjusted driving state and dots are formed on the target.

  In the liquid ejecting apparatus of the present invention, the head is driven and controlled so that the liquid is ejected as droplets from the nozzle in a state where the potential difference is applied to the head or the liquid receiving means by the potential difference applying means at a predetermined timing. The mass of the droplet discharged from the nozzle is determined based on the magnitude of the change in the electrical state of the head or the liquid receiving means detected by the change detecting means, and when the dot formation on the target is instructed, the determination result Then, the head is driven and controlled so that droplets are ejected from the nozzle and dots are formed on the target with the adjusted driving state. Since the head is controlled by adjusting the head drive state after determining the mass of the droplet ejected from the head, the ejection characteristics of the droplet from the nozzle are more accurately grasped and dots are formed on the target. Can be performed with higher quality.

  In such a liquid ejection apparatus according to the present invention, the control unit adjusts the driving state based on the determined mass of the droplet so that the mass of the droplet ejected from the nozzle is within a reference mass range. It may be a means for driving and controlling the head. In this way, it is possible to form dots by ejecting droplets within the reference mass range from the nozzles regardless of the ejection characteristics of the nozzles for each apparatus.

  The liquid ejection apparatus according to the present invention further includes temperature detection means for detecting the temperature of the head, and the control means further drives the head by adjusting the driving state based on the detected head temperature. It can also be a means for controlling. In this way, it is possible to cope with a change in the ejection characteristics of the nozzle caused by a change in the temperature of the head.

  Furthermore, in the liquid ejection apparatus of the present invention, the control means may be means for determining the mass of the droplet every time when the formation of dots on the target is instructed as the predetermined timing. The control means may be means for determining the mass of the droplet every time dots are formed on a predetermined number of targets as the predetermined timing. In this way, the timing for determining the mass of the droplet can be made more appropriate.

  Further, in the liquid ejection apparatus of the present invention, the head is formed with a plurality of nozzles arranged in a row for each color, and the control unit drops droplets from one of the nozzles in the nozzle row for each color. It is also possible to use a means for determining the mass of the droplets by discharging the droplets. In this way, more accurate dots can be formed for each color. In this case, the control means may be means for determining the mass of the droplet for each color using nozzles having the same row position. In this way, it is possible to reduce the influence of the deviation in the ejection characteristics of the nozzles based on the row position.

The method for controlling the liquid ejection apparatus of the present invention includes:
A head in which a nozzle is formed; a liquid receiving means for receiving liquid ejected from the nozzle; a potential difference applying means for applying a potential difference to the head or the liquid receiving means; and an electrical state of the head or the liquid receiving means An electrical change detecting means for detecting the change of the liquid, and a method for controlling a liquid ejection apparatus for ejecting a liquid to a target to form dots,
The head is driven and controlled so that liquid is ejected as droplets from the nozzle in a state where a potential difference is applied to the head or the liquid receiving unit by the potential difference applying unit at a predetermined timing and the electrical change detecting unit. Determining the mass of the droplets ejected from the nozzle based on the magnitude of the change in the electrical state detected by, and driving the head based on the determination result when instructed to form dots on the target The head is driven and controlled so that droplets are ejected from the nozzle and dots are formed on the target with the adjusted driving state.

  According to the control method of the liquid discharge apparatus of the present invention, the head is driven so that the liquid is discharged as droplets from the nozzle in a state where the potential difference is applied to the head or the liquid receiving means by the potential difference applying means at a predetermined timing. The mass of the droplet ejected from the nozzle was determined based on the magnitude of the change in the electrical state of the head or the liquid receiving means detected by the electrical change detecting means, and the formation of dots on the target was instructed At this time, the head driving state is adjusted based on the determination result, and the head is driven and controlled so that droplets are ejected from the nozzle and dots are formed on the target with the adjusted driving state. Since the head is controlled by adjusting the head drive state after determining the mass of the droplet ejected from the head, the ejection characteristics of the droplet from the nozzle are more accurately grasped and dots are formed on the target. Can be performed with higher quality.

  Next, an embodiment embodying the present invention will be described. FIG. 1 is a configuration diagram showing an outline of the configuration of the ink jet printer 20 according to the present embodiment, FIG. 2 is an explanatory diagram showing electrical connection of the print head 24, and FIG. 3 shows an outline of the configuration of the ink droplet mass determination device 50. It is a block diagram.

  As shown in FIG. 1, the inkjet printer 20 of the present embodiment includes a paper feed mechanism 31 that transports the recording paper S from the back to the front in the drawing by driving a paper feed roller 35 by a drive motor 33, and a paper feed mechanism 31. A printer mechanism 21 that performs printing by ejecting ink droplets from the print head 24 onto the recording paper S conveyed on the platen 40, and the print head 24 that is formed at the right end of the platen 40 in the drawing and seals as necessary. A capping device 41 that performs cleaning by sucking ink in the print head 24 with a pump (not shown), and preventing the ink from drying and solidifying at the nozzle tip of the print head 24 formed at the left end of the platen 40 in the drawing. Therefore, a flushing unit for performing a flushing operation for ejecting ink droplets at a predetermined timing regardless of print data Comprising a 2, and the flushing unit 42 ink determines its mass by ejecting ink droplets from the print head 24 to the drop mass determination device 50 (see FIG. 3), and a controller 70 that controls the entire inkjet printer 20.

  The printer mechanism 21 includes a carriage motor 34a disposed on the right side of the mechanical frame 80, a driven roller 34b disposed on the left side of the mechanical frame 80, a carriage belt 32 installed on the carriage motor 34a and the driven roller 34b, A carriage 22 that reciprocates left and right along the guide 28 by a carriage belt 32 as the carriage motor 34a is driven, and yellow (Y) containing a dye or pigment as a colorant in water as a solvent mounted on the carriage 22 ), Magenta (M), cyan (C), and black (K) ink cartridges 26 that individually contain ink, and a print head 24 that receives ink from the ink cartridge 26 and ejects ink droplets. Prepare. A linear encoder 36 for detecting the position of the carriage 22 is disposed on the rear surface of the carriage 22, and the position of the carriage 22 is managed by the linear encoder 36.

  As shown in FIG. 2, the print head 24 includes a plurality of nozzles 23C, 23M, 23Y, and 23K for cyan (C), magenta (M), yellow (Y), and black (K) for each color (this embodiment). In this case, a nozzle plate 27 made of stainless steel on which four nozzle rows 43C, 43M, 43Y, and 43K arranged in one row are formed, and an ink chamber 29 that communicates with the nozzle 23 together with the nozzle plate 27 are provided. A cavity plate 25 to be formed, a ceramic (for example, zirconia ceramic) diaphragm 49 that forms the upper wall of the ink chamber 29, and a piezoelectric element 48 (for example, zirconate titanate) attached to the upper surface of the diaphragm 49 And a mask circuit 47 as a drive circuit that is formed on the head drive substrate 30 and outputs a drive signal to the piezoelectric element 48, and a mask. By applying a voltage from the road 47 to the piezoelectric element 48 to eject ink droplets pressurizing ink by depressing the upper wall of the ink chamber 29 by the piezoelectric element 48. Here, all of the nozzles 23C, 23M, 23Y, and 23K are collectively referred to as the nozzle 23, and all of the nozzle rows 43C, 43M, 43Y, and 43K are collectively referred to as the nozzle row 43. Hereinafter, driving of the print head 24 will be described using the black (K) nozzle 23K.

  The mask circuit 47 receives the original signal ODRV and the print signal PRTn generated by the head drive waveform generation circuit 60, generates the drive signal DRVn based on the input original signal ODRV and the print signal PRTn, and outputs the piezoelectric element 48. Output to. Note that the last n of the print signal PRTn and the last n of the drive signal DRVn are numbers for specifying the nozzles included in the nozzle row, and in this embodiment, the nozzle row is composed of 180 nozzles. , N is an integer value from 1 to 180. The head drive waveform generation circuit 46 generates the first pulse P1, the second pulse P2, and the third pulse P3 as the original signal ODRV within a period of one pixel (within the time during which the carriage 22 crosses the section of one pixel). The mask circuit 47 that outputs a signal with three pulses as a repeating unit to the mask circuit 47 and receives the original signal ODRV is unnecessary among the three pulses included in the original signal ODRV based on the separately input print signal PRTn. By masking the pulse, only the necessary pulse is output to the piezoelectric element 48 of the nozzle 23K as the drive signal DRVn. At this time, when only the first pulse P1 is output to the piezoelectric element 48 as the drive signal DRVn, one shot of ink droplet is ejected from the nozzle 23K, and a small dot (small dot) is formed on the recording paper S. When the first pulse P1 and the second pulse P2 are output to the piezoelectric element 48, two shots of ink droplets are ejected from the nozzle 23K, and medium size dots (medium dots) are formed on the recording paper S. When the first pulse P1, the second pulse P2, and the third pulse P3 are output to the piezoelectric element 48, three shots of ink droplets are ejected from the nozzle 23K, and a large size dot (large dot) is formed on the recording paper S. Is formed. As described above, the inkjet printer 20 can form dots of three sizes by adjusting the amount of ink ejected in one pixel section. The nozzles 23C, 23M, 23Y and nozzle rows 43C, 43M, 43Y of colors other than black (K) are the same as the nozzle 23K and nozzle row 43K.

  FIG. 4 shows how ink droplets are ejected from the nozzles 23 when the first pulse P1 (voltage) is applied to the piezoelectric element 48. As shown in the figure, when the potential acting on the piezoelectric element 48 rises from the reference potential Vo, the piezoelectric element 48 is deformed and the pressure in the ink chamber 29 is reduced, so that the ink near the nozzle 23 is slightly drawn into the ink chamber 29 ( (See (a) in FIG. 4). Next, when the potential acting on the piezoelectric element 48 is lowered, the piezoelectric element 48 is deformed to pressurize the ink chamber 29, so that the ink in the ink chamber 29 is pushed out from the nozzle 23. It stays (see (b) in FIG. 4). When the potential acting on the piezoelectric element 48 returns to the reference potential Vo again, the pressurized state of the ink chamber 29 is released, and the ink pushed out of the nozzle 23 is cut off from the nozzle 23 and ejected as ink droplets ( (See (c) in FIG. 4). At this time, the greater the difference between the maximum value (maximum potential) and the minimum value (minimum potential) of the potential acting on the piezoelectric element 48 (hereinafter referred to as the drive voltage V), the more the piezoelectric element 48 is deformed. The pressure change in the chamber 29 increases. Therefore, the larger the drive voltage V, the more ink can be pushed out from the nozzles 23, and the mass (size) of the ink droplets ejected from the nozzles 23 becomes larger. That is, by changing the drive voltage V, the mass of the ink droplet can be corrected. The mass of the ink droplet is the value of the reference potential Vo, the slope when changing from the reference potential Vo to the highest potential, the slope when changing from the highest potential to the lowest potential, and the slope when returning from the lowest potential to the reference potential Vo. Therefore, the mass of the ink droplets may be corrected by adjusting a part or all of them together with the driving voltage V or instead of the driving voltage V.

  As shown in FIG. 3, the ink droplet mass determination device 50 uses the flushing portion 42 (see FIG. 1) as an inspection region 52 to discharge charged ink droplets from the nozzles 23 of the print head 24 to the inspection region 52. Is configured to determine the mass of the ejected ink droplet by detecting a voltage change occurring in the print head 24, and is connected to the nozzle plate 27 and a voltage application circuit 53 that applies a voltage to the nozzle plate 27 of the print head 24. And a voltage detection circuit 54.

  The inspection area 52 includes a sponge-like upper ink absorber 55 on which ink droplets directly land, a sponge-like lower ink absorber 56 that absorbs ink droplets transmitted downward from the upper ink absorber 55, and an upper side. A mesh-shaped electrode member 57 disposed between the ink absorber 55 and the lower ink absorber 56 is disposed. The sponge of the upper ink absorber 55 is conductive and has high permeability so that the landed ink droplet can be moved downward quickly. Here, an ester urethane sponge (trade name: Everlite SK-E, Bridgestone Co., Ltd.) is used. The sponge of the lower ink absorber 56 has a higher ink holding power than the upper ink absorber 55 and is made of a nonwoven fabric such as felt. Here, the nonwoven fabric (trade names: Kinocloth, Oji Kinocloth ( Co., Ltd.) is used. The electrode member 57 is formed as a grid-like mesh made of a metal made of stainless steel (for example, SUS). Therefore, the ink once absorbed by the upper ink absorber 55 is absorbed and held by the lower ink absorber 56 through the gap between the grid-like electrode members 57. The electrode member 57 is grounded via a mechanical frame 80 (see FIG. 1), and the electrode member 57 is in contact with the conductive upper ink absorber 55. The surface is also grounded in the same manner as the electrode member 57. If the inspection region 52 includes the power member 57, the upper ink absorber 55 and the lower ink absorber 56 may not be included.

  The voltage application circuit 53 boosts the voltage of the electrical wiring of several volts drawn inside the inkjet printer 20 to several tens to several hundreds volts through a booster circuit (not shown), and switches the DC voltage Ve after this boosting to a switch The voltage is applied to the nozzle plate 27 of the print head 24 via SW.

  The voltage detection circuit 54 is connected to the nozzle plate 27 and integrates and inverts and amplifies the voltage signal of the nozzle plate 27 and outputs the signal to the controller 70. The voltage detection circuit 54 and a booster circuit (not shown) are mounted on the head driving substrate 30.

  As shown in FIG. 1, the controller 70 is configured as a microprocessor centered on the CPU 72, and includes a ROM 73 that stores various processing programs, a RAM 74 that temporarily stores data and stores data, It includes a flash memory 75 in which data can be written and erased, an interface (I / F) 79 for exchanging information with an external device, and an input / output port (not shown). The RAM 74 is provided with a print buffer area, and print data sent from the user PC 10 via the I / F 79 is stored in this print buffer area. The controller 70 includes a voltage signal from the voltage detection circuit 54, a position signal of the carriage 22 from the linear encoder 36, a head temperature Th from a temperature sensor 90 (for example, a thermistor) attached to the print head 24, and the like. A print job or the like input via an input port (not shown) and output from the user PC 110 is input via the I / F 79. Further, the controller 70 controls the print head 24 (including the mask circuit 47 and the piezoelectric element 48), the switch signal to the switch SW, the control signal to the head drive waveform generation circuit 60, and the drive to the drive motor 33. A signal, a drive signal for the carriage motor 34a, and the like are output via an output port (not shown), and print status information for the user PC 110 is output via the I / F 79.

  Next, the operation of the ink jet printer 20 of the present embodiment configured as described above, particularly the operation when performing printing while adjusting the ink droplets ejected from the nozzles 23 to an appropriate mass (size) will be described. FIG. 5 is a flowchart of a print processing routine executed by the CPU 72 of the controller 70. This main routine is repeatedly executed every predetermined time (for example, every several msec) after the power of the inkjet printer 20 is turned on.

  When the print processing routine is executed, the CPU 72 of the controller 70 first determines whether or not there is print-waiting data (step S100). If there is no print-waiting data, this routine is terminated without doing anything. When there is print waiting data, the number N of printed sheets is compared with a threshold value Nref (step S110). When the number N printed is greater than or equal to the threshold value Nref, the number N of printed sheets is reset (step S120), and ink droplet mass determination processing is performed. Execute (Step S130). Here, the threshold value Nref determines the execution interval of the ink droplet mass determination process, and is set to 5 or 10 sheets. Therefore, the ink droplet mass determination process is executed every time the number of sheets corresponding to the threshold value Nref is printed. Here, the description of the printing process routine is interrupted, and the ink droplet mass determination process will be described. FIG. 6 is a flowchart illustrating an example of ink droplet mass determination processing executed by the CPU 72 of the controller 70.

  When the ink droplet mass determination process is executed, the CPU 72 of the controller 70 first drives the carriage motor 34a to move the carriage 22 to the flushing unit 42 (step S300). As a result, the nozzle plate 27 and the inspection area 52 of the print head 24 are in a state of facing each other. Subsequently, the switch SW of the voltage application circuit 53 is turned on so that a voltage is applied to the nozzle plate 27 (step S310), and an uninspected nozzle array among the nozzle arrays 43 of each color is set as an inspection target nozzle array. At the same time (step S320), the m-th nozzle among the nozzles 23 of the set nozzle row to be inspected (for example, the nozzle arranged in the approximate center of the nozzle row to be inspected (the 91st nozzle in this embodiment)) is driven. (Step S330). Then, the output level Vout of the output waveform signal from the voltage detection circuit 54 is input (step S340), and the mass M of the ink droplet ejected from the nozzle 23 is set based on the input output level Vout (step S350). Here, in this embodiment, the ink drop mass M corresponds to the map when the relationship between the output level Vout and the ink drop mass M is obtained in advance and stored in the ROM 73 as a map, and the output level Vout is given. It was set by deriving the ink droplet mass M. An example of this map is shown in FIG. As illustrated, the ink droplet mass M tends to increase as the output level Vout increases. As shown in FIG. 3, since the voltage is applied to the nozzle plate 27 by the voltage application circuit 53, charged ink droplets are ejected from the nozzle 23. At this time, a voltage change occurs in the nozzle plate 27, and the nozzle The voltage is detected as an output signal waveform by the voltage detection circuit 54 connected to the plate 27. The amplitude of the detected output signal waveform depends on the mass (size) of the ink droplet ejected from the nozzle 23, and is small when the ink droplet is smaller than the proper mass and large when the ink droplet is larger than the proper mass. Become. Therefore, the mass of the ink droplet from the nozzle 23 can be determined by examining the output level Vout. In the present embodiment, the amplitude of the output signal waveform is weak when ejecting ink droplets for one shot, and therefore the operation of outputting all of the first to third pulses P1 to P3 is repeated eight times to obtain the total. Ink droplets for 24 shots were ejected. As a result, the output signal waveform becomes an integrated value of ink droplets for 24 shots, so that a sufficiently large output signal waveform can be obtained from the voltage detection circuit 54.

  When the ink droplet mass M is set in this manner, when there are other uninspected nozzle rows 43 remaining (step S360), the process returns to step S320 to set the uninspected nozzle row 43 as the inspection target nozzle row and set the inspection. The process of setting the ink droplet mass M based on the output level Vout detected by the voltage detection circuit 54 by driving the ink droplets to be ejected from the m-th nozzle among the nozzles of the target nozzle row is repeated ( Steps S320 to S350). As described above, the ink droplets are ejected using the nozzles of the same number in all the nozzle rows 43 because the mass of the ink droplets ejected from the nozzles 23 may be biased depending on the positions in the nozzle rows 43. This is to avoid being affected. If no uninspected nozzle row remains in step S360, the switch SW of the voltage application circuit 53 is turned off (step S370), and this routine ends. The ink drop mass determination process has been described above.

  Returning to step S130 of the printing process routine of FIG. 5, when the ink drop mass determination process is executed in this way, each color is determined whether or not the determined ink drop mass M is within an allowable range determined by the lower limit value ML and the upper limit value MH. For each nozzle row 43 (step S140), and when the ink droplet mass M is within the allowable range, the process proceeds to the next process without updating the mass correction coefficient Km of the corresponding nozzle row 43, and the ink droplet mass M is determined as follows. When the value is smaller than the lower limit value ML, the predetermined value K1 is added to the mass correction coefficient Km of the corresponding nozzle row 43 and updated to a new mass correction coefficient K (step S150), and the ink droplet mass M is larger than the upper limit value MH. Sometimes, the predetermined value K2 is subtracted from the mass correction coefficient Km of the corresponding nozzle row 43 and updated to a new mass correction coefficient Km (step S160). Here, the mass correction coefficient K is set to a value of 1 by the initialization routine when the power is turned on.

  Then, the head temperature Th from the temperature sensor 90 is input (step S170), and the input head temperature Th is set to the reference temperature Tb of the ink droplet mass M determined by the ink droplet mass determination processing (step S180). Here, the reference temperature Tb is set as a temperature condition (head temperature Th) at the time when the ink droplet mass determination process of FIG. 6 is executed. As described above, the reference temperature Tb is set even if the ink drop mass M is accurately determined by the ink drop mass determination process, and when the head temperature Th subsequently changes, the ink drop mass M is also changed accordingly. Since it changes, it is based on the necessity to adjust the mass correction coefficient K mentioned above.

  When the mass correction coefficient Km is set for each nozzle row 43 in this way, a product obtained by multiplying the mass correction coefficient Km and the reference drive voltage Vbase for each nozzle row 43 is set as the execution drive voltage V (step S190), and the set execution drive is set. The head drive waveform generation circuit 60 is controlled so that a head drive waveform of voltage V is generated for each nozzle row 43 (step S200), print processing is executed (step S210), and the number N of prints is incremented by a value of 1. (Step S220), and this routine is finished. Here, the reference drive voltage Vbase that is set in advance and stored in the ROM 73 is used. The reference drive voltage Vbase is stored as one of head identification information (head ID) representing head characteristics at the time of manufacturing in the manufacturing process inspection of the ink jet printer 20. Information and ink discharge amount information. As the head identification information, in addition to the information stored in the ROM 73, code information such as a barcode displayed on the head ID seal may be read by a reading device.

  When it is determined in step S110 that the number N of printed sheets is less than the threshold value Nref, it is determined that the ink droplet mass determination process is not performed at the timing, and the current head temperature is determined by executing the temperature correction process illustrated in FIG. The execution drive voltage V reflecting Th is set (step S230), the processing after step S200 is executed, and this routine is terminated. Here, in the temperature correction processing of FIG. 8, the head temperature Th from the temperature sensor 90 is input (step S400), and the deviation as the deviation between the input head temperature Th and the reference temperature Tb set in step S180 of the printing processing routine. A temperature deviation ΔT (= Th−Tb) is calculated (step S410), and a value obtained by multiplying the calculated temperature deviation ΔT, the coefficient α, the current mass correction coefficient Km, and the reference drive voltage Vbase is set as the execution drive voltage V. (Step S420). The coefficient α is a coefficient for adjusting the current mass correction coefficient Km set based on the reference temperature Tb based on the temperature deviation ΔT. Thereby, even if the head temperature Th changes after the ink droplet mass M is determined, it can be adjusted to an appropriate execution drive voltage V corresponding to the change.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. In this embodiment, the print head 24 corresponds to a “head”, the inspection region 52 corresponds to a “liquid receiving unit”, the voltage application circuit 53 corresponds to a “potential difference applying unit”, and the voltage detection circuit 54 The controller 70 that corresponds to “change detection means” and executes the print processing routine of FIG. 5 corresponds to “control means”. In the present embodiment, an example of the method for controlling the liquid ejection apparatus of the present invention is also clarified by describing the operation of the inkjet printer 20.

  According to the ink jet printer 20 described in detail above, the mass of the ejected ink droplet is determined by ejecting the charged ink droplet from the nozzle 23 of the print head 24 to the inspection region 52 and detecting the voltage change generated at that time. An ink droplet mass determination device 50 is provided, and each time the number of printed sheets N becomes equal to or greater than the threshold value Nref, an ink droplet is ejected from the nozzle 23 to the inspection region 52 and the ink droplet mass determination device 50 determines the ink droplet mass M. Since the mass correction coefficient Km is set based on the drop mass M, the execution drive voltage V is set with the set mass correction coefficient Km, the head drive waveform is generated with the set execution drive voltage V, and the printing process is executed. An ink droplet having an appropriate mass can be ejected from the nozzle 23. As a result, the print quality can be further improved. In addition, after the ink droplet mass determination device 50 determines the ink droplet mass M, the execution drive voltage V is adjusted in consideration of the head temperature Th, so that it is possible to cope with changes in the head temperature Th.

  In the present embodiment, the timing (interval) for determining the ink droplet mass M is set for each predetermined page number Nref and the timing (interval) for performing temperature correction based on the head temperature Th is set for each page. The former timing is set for each print job, and the latter timing is set for each predetermined number of pages in the print job. The former timing is set for each predetermined number of pages and the latter timing is set for each page. The latter timing may be set for each page, and the latter timing may be set for each predetermined number of passes in one page. Alternatively, the determination of the ink droplet mass M may be performed only when the power is turned on. Note that the determination of the ink droplet mass M requires more time than temperature correction, so it is not preferable to perform the determination in the middle of one page.

  In the present embodiment, the temperature correction process of FIG. 8 is executed, but this process may be omitted.

  In the present embodiment, ink droplets are ejected from one nozzle for each nozzle row 43 to determine the ink droplet mass M, and based on this ink droplet mass M, the mass of ink droplets ejected for each nozzle row 43 is corrected. However, ink droplets are ejected from a plurality of nozzles 23 (including all nozzles) in the same nozzle row 43 to determine the ink droplet mass M for each nozzle 23 and to the average value of the determined ink droplet mass M. Based on this, the mass correction of the ink droplets of the nozzle row 43 may be performed. Further, in the case where the execution drive voltage V common to the plurality of nozzle rows is set, the ink droplet mass M is determined by ejecting ink droplets from one nozzle of the plurality of nozzle rows, and the ink droplet mass M is set to this ink droplet mass M. Based on this, it is also possible to perform a common mass correction for a plurality of nozzle rows, or eject ink droplets from a plurality of nozzles (including all nozzles) in the plurality of nozzle rows to produce ink droplet masses for each of the plurality of nozzles. A common mass correction may be performed for the plurality of nozzle rows based on the average value of the determined ink droplet mass M. Further, in an apparatus of a type that can be driven individually by setting the execution drive voltage V for each nozzle, the ink droplet mass M is determined for each nozzle, and the ink for each nozzle is determined based on this ink droplet mass M. Drop mass correction may be performed.

  In this embodiment, the ink droplet mass M is determined for each color using the nozzles of the same number among the nozzles 23 of the nozzle row 43 of each color, but the ink droplets for each color using the nozzles of different numbers. The mass M may be determined.

  In the present embodiment, the flushing portion 42 is used as the inspection region 52, and ink droplets are ejected from the print head 24 to the inspection region 52 to determine the mass M. However, the inspection region is provided in a region other than the flushing portion 42. It is also possible to determine the mass M by ejecting ink droplets to the area. For example, the inspection area may be provided in the capping device 41.

  In this embodiment, a voltage is applied to the print head 24 (nozzle plate 27) and the inspection region 52 is grounded to the ground potential. However, the print head 24 is grounded to the ground potential and a voltage is applied to the inspection region 52. May be.

  In this embodiment, the voltage detection circuit 54 is connected to the print head 24 (nozzle plate 27) to detect a change in the electrical state on the print head 24 side, but the voltage detection circuit 54 is connected to the inspection region 52. Then, a change in the electrical state on the inspection region 52 side may be detected.

  In the present embodiment, an ink jet printer is shown as an example of the ink jet recording apparatus of the present invention. However, the present invention is not particularly limited as long as the apparatus adopts an ink jet recording system. You may apply to the manufacturing apparatus for manufacturing devices, such as a color filter, besides an OA apparatus.

  In the above-described embodiment, the example in which the fluid ejection device of the present invention is embodied in the ink jet printer 20 has been described. However, a liquid (dispersion) in which particles of liquid other than ink and functional material are dispersed, a gel The present invention may be embodied in a fluid ejection device that ejects a fluid or the like, or may be embodied in a fluid ejection device that ejects a solid that can be ejected as a fluid. For example, a liquid discharge device that discharges a liquid in which a material such as an electrode material or a color material used for manufacturing a liquid crystal display, an EL (electroluminescence) display, a surface emitting display, and a color filter is dissolved, or a liquid material in which the material is dispersed It is good also as a liquid discharge apparatus which discharges the liquid used as a liquid material discharge apparatus which discharges, and a sample used as a precision pipette. Also, transparent resin liquids such as UV curable resin to form liquid ejection devices that pinpoint lubricating oil to precision machines such as watches and cameras, micro hemispherical lenses (optical lenses) used for optical communication elements, etc. A liquid discharge device that discharges a liquid onto the substrate, a liquid discharge device that discharges an etching solution such as acid or alkali to etch the substrate, and a fluid discharge device that discharges gel.

  The embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and can of course be implemented in various modes as long as they belong to the technical scope of the present invention.

1 is a configuration diagram illustrating an outline of a configuration of an inkjet printer 20 according to an embodiment. FIG. 3 is an explanatory diagram showing electrical connection of the print head 24. FIG. 2 is a configuration diagram showing an outline of the configuration of an ink droplet mass determination device 50. Explanatory drawing which shows a mode that an ink drop discharges. 6 is a flowchart illustrating an example of a print processing routine. 6 is a flowchart illustrating an example of ink droplet mass determination processing. FIG. 6 is an explanatory diagram illustrating an example of an ink droplet mass setting map. The flowchart which shows an example of a temperature correction process.

Explanation of symbols

  10 user PC, 20 inkjet printer, 21 printer mechanism, 22 carriage, 23, 23Y, 23M, 23C, 23K nozzle, 24 print head, 25 cavity plate, 26 ink cartridge, 27 nozzle plate, 28 guide, 29 ink chamber, 30 Head drive substrate, 31 paper feed mechanism, 32 carriage belt, 33 drive motor, 34a carriage motor, 34b driven roller, 35 paper feed roller, 40 platen, 41 capping device, 42 flushing section, 43, 43Y, 43M, 43C, 43K nozzle array, 47 mask circuit, 48 piezoelectric element, 49 diaphragm, 50 ink drop mass determination device, 52 inspection area, 53 voltage application circuit, 54 voltage detection circuit, 55 upper ink absorber, 56 lower ink Absorbent body, 57 electrode member 60 head drive waveform generator, 70 a controller, 72 CPU, 73 ROM, 74 RAM, 75 a flash memory, 79 an interface (I / F), 80 mechanical frame, 90 a temperature sensor.

Claims (8)

A liquid ejection apparatus that ejects liquid to a target to form dots,
A head on which a nozzle is formed;
Liquid receiving means for receiving the liquid discharged from the nozzle;
A potential difference applying means for applying a potential difference to the head or the liquid receiving means;
Electrical change detection means for detecting a change in electrical state of the head or the liquid receiving means;
The head is driven and controlled so that liquid is ejected as droplets from the nozzle in a state where a potential difference is applied to the head or the liquid receiving unit by the potential difference applying unit at a predetermined timing and the electrical change detecting unit. Determining the mass of the droplets ejected from the nozzle based on the magnitude of the change in the electrical state detected by, and driving the head based on the determination result when instructed to form dots on the target A liquid ejecting apparatus comprising: control means for driving and controlling the head so that droplets are ejected from the nozzle with the adjusted driving state to form dots on the target.   The control unit is a unit that controls the driving of the head by adjusting the driving state based on the determined mass of the liquid droplet so that the mass of the liquid droplet ejected from the nozzle falls within a reference mass range. The liquid ejection apparatus according to claim 1. The liquid ejection device according to claim 1 or 2,
Temperature detecting means for detecting the temperature of the head,
The liquid ejection apparatus, wherein the control unit is a unit that further controls the driving state by adjusting the driving state based on the detected temperature of the head.   4. The liquid ejection apparatus according to claim 1, wherein the control unit is a unit that determines the mass of the droplet every time the formation of dots on the target is instructed as the predetermined timing.   5. The liquid ejecting apparatus according to claim 1, wherein the control unit is a unit that determines a mass of the droplet every time dots are formed on a predetermined number of targets as the predetermined timing. 6. The liquid ejection device according to any one of claims 1 to 5,
The head is formed by forming a plurality of nozzles for each color in a row,
The control means is means for discharging a droplet from one of the nozzles of the nozzle row for each color and determining the mass of the droplet.   The liquid ejecting apparatus according to claim 6, wherein the control unit is a unit that determines the mass of the droplet for each color using nozzles having the same row position. A head in which a nozzle is formed; a liquid receiving means for receiving liquid ejected from the nozzle; a potential difference applying means for applying a potential difference to the head or the liquid receiving means; and an electrical state of the head or the liquid receiving means An electrical change detecting means for detecting the change of the liquid, and a method for controlling a liquid ejection apparatus for ejecting a liquid to a target to form dots,
The head is driven and controlled so that liquid is ejected as droplets from the nozzle in a state where a potential difference is applied to the head or the liquid receiving unit by the potential difference applying unit at a predetermined timing and the electrical change detecting unit. Determining the mass of the droplets ejected from the nozzle based on the magnitude of the change in the electrical state detected by, and driving the head based on the determination result when instructed to form dots on the target A control method for a liquid ejection apparatus, wherein the head is driven and controlled so that droplets are ejected from the nozzle and dots are formed on the target with the adjusted driving state.

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