JP2021160338A - Droplet discharge apparatus, droplet discharge method, and modeling program - Google Patents

Abstract

To allow handling of an operation by estimating a cause of dirt on a nozzle surface of a liquid discharge device.SOLUTION: There is provided a droplet discharge apparatus comprising: a discharge head that discharges a droplet through a nozzle onto a discharge receiving medium formed of powder; a nozzle surface observation unit that observes a nozzle surface of the nozzle of the discharge head; a calculation unit that calculates an adhesion amount of an attached matter to the nozzle surface based on an observation result of the nozzle surface observation unit; and a determination unit that determines, based on a calculation result from the calculation unit, an operation on a control target that controls at least one of a mass and a discharge speed of the droplet.SELECTED DRAWING: Figure 6

Description

The present invention relates to a droplet ejection device, a droplet ejection method and a modeling program.

Today, the process of ejecting a droplet onto a medium to be ejected (modeling powder) accurately arranged on the ejection surface of the droplet, further laminating the powder on the droplet, and ejecting the droplet to solidify it is repeated. A three-dimensional modeling device that forms a three-dimensional model by an additive manufacturing method is known.

In such a three-dimensional modeling apparatus, since it is desired to land the droplets on the powder with high accuracy, the ejection speed of the droplets should be set to a certain speed or higher, and the distance between the ejection surface for ejecting the droplets and the powder should also be increased. It is preferably below a certain level. Further, since it is desired to improve the productivity (production rate) of the three-dimensional modeled object, it is preferable to increase the size of the droplets by a certain amount or more. Further, in order to increase the resolution (surface property or accuracy) of the three-dimensional modeled object, it is preferable to keep the size (particle size) of the powder below a certain level.

Under such conditions, the powder tends to adhere to the nozzle surface of the ejection head that ejects the droplets, resulting in poor ejection of the droplets. If the nozzle surface is frequently cleaned and maintained in order to prevent this ejection failure, the maintenance time increases and the productivity decreases. Further, the durability of the discharge head is lowered due to the wear of the water-repellent surface of the nozzle due to maintenance, and the droplets are consumed by the maintenance, which causes problems such as a drop in ink yield.

As a technique for dealing with such a problem, a technique for observing the state of the nozzle surface and maintaining the nozzle surface based on the observation result is known.

In Patent Document 1 (Japanese Unexamined Patent Publication No. 2008-132786), when a discharge abnormality is detected and adhesion of a fixed substance on the discharge port surface is not detected, a preliminary discharge operation and a liquid suction operation in the liquid discharge head are performed. A liquid discharge device that performs at least one of the operations is disclosed. As a result, effective wiping according to the situation can be realized, and the cleaning function can be improved.

However, with the conventional technology of observing the nozzle surface of the discharge head and maintaining the nozzle surface, the reliability of the nozzle can be ensured, but if the root cause is the powder control unit, only the nozzle surface is cleaned. Does not eliminate the root cause. Therefore, there is a concern that the productivity is lowered due to the increased cleaning frequency, and the durability of the water-repellent film of the nozzle is impaired.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a droplet ejection device, a droplet ejection method, and a modeling program capable of estimating the cause of dirt on the nozzle surface and dealing with it.

In order to solve the above-mentioned problems and achieve the object, the present invention has a discharge head that discharges droplets to a discharge medium formed of powder via a nozzle, and a nozzle surface of the nozzle of the discharge head. Based on the observation results of the nozzle surface observation unit and the nozzle surface observation unit, the calculation unit that calculates the amount of deposits adhering to the nozzle surface, and the calculation unit that calculates the mass and ejection of droplets. It has a determination unit for determining an operation with respect to a controlled object that controls at least one of the speeds.

According to the present invention, there is an effect that the cause of the dirt on the nozzle surface can be estimated and dealt with.

FIG. 1 is a top view showing a main part of the three-dimensional modeling apparatus of the first embodiment. FIG. 2 is a side view showing a part of the three-dimensional modeling apparatus of the first embodiment as seen through. FIG. 3 is a diagram showing a state in which the discharge head discharges droplets to the powder in the modeling tank. FIG. 4 is a block diagram showing a hardware configuration of the three-dimensional modeling apparatus of the first embodiment. FIG. 5 is a functional block diagram of the three-dimensional modeling apparatus of the first embodiment. FIG. 6 is a flowchart showing the flow of the observation operation of the nozzle surface in the three-dimensional modeling apparatus of the first embodiment. FIG. 7 is a flowchart showing a flow of observation operation of the nozzle surface in the stereoscopic imaging apparatus of the second embodiment. FIG. 8 is a diagram showing a nozzle surface of the ejection head in a state where the ink detection light from the ink detection light source and the powder detection light from the powder detection light source are irradiated. FIG. 9 is a diagram showing a nozzle surface of a discharge head in a state in which a striped pattern light is irradiated from a light source in a stereoscopic imaging device as a modified example.

Hereinafter, the three-dimensional modeling apparatus according to the embodiment will be described with reference to the attached drawings.

[First Embodiment]
(Appearance configuration of 3D modeling device)
First, FIG. 1 is a top view showing a main part of the three-dimensional modeling apparatus of the first embodiment. Further, FIG. 2 is a side view showing a part of the three-dimensional modeling apparatus of the first embodiment as seen through. The three-dimensional modeling apparatus of the first embodiment forms a three-dimensional model by repeating a process of laminating powders of resin, metal, ceramics, etc., and ejecting droplets by an inkjet method to solidify them. ..

As an example, the droplets will be described as being ejected by an inkjet method, but any droplets such as a dispenser may be ejected. Further, although a three-dimensional modeling device that performs three-dimensional modeling will be described as an example, any device provided with a discharge head that discharges droplets can obtain the effects described later. Further, the dirt that can adhere to the nozzle surface of the discharge head can obtain the effect described later even in the case of an object other than powder.

In FIGS. 1 and 2, the powder 1 is supplied into the modeling tank 3 by a powder supply unit 2 such as a hopper or the like. The surface of the powder 1 is accurately smoothed by moving the recoat roller 4 while rotating on the recoat roller 4.

A surplus powder receiving tank 9 is provided adjacent to the modeling tank 3. When the surface of the powder 1 is smoothed, the surplus powder 1 among the powders 1 transferred by the recoat roller 4 falls into the surplus powder receiving tank 9. A powder supply device (reference numeral 554 in FIG. 4) is provided on the powder supply unit 2, and the surplus powder 1 that has fallen into the surplus powder receiving tank 9 is the powder supply device 554. Is returned to the powder supply unit 2.

The powder supply unit 2 is moved up and down in the vertical direction (height direction) of FIG. 2 by the motor 27 shown in FIG. The modeling stage 10 is moved up and down in the vertical direction of FIG. 2 by the motor 28 shown in FIG.

The powder supply unit 2 may move integrally with the recoat roller 4 or may move separately from the recoat roller 4. Further, the powder supply unit 2 may be fixed (it does not have to move). Further, the powder supply unit 2 is not limited to being arranged above the modeling tank 3 as shown in FIG. 1, and although not shown, a supply tank is provided next to the modeling tank, and the cover of the supply tank is provided. The discharge medium may be arranged by a recoat roller. In addition to smoothing the powder 1 with the recoat roller 4, for example, a plate-shaped blade may be used to smooth the powder 1. Further, it may be appropriately designed in consideration of factors such as the size, cost, operation efficiency, accuracy or reliability of arranging the ejected medium of the entire device.

Further, in the configuration of FIG. 1, the shape of the modeled object is formed for each layer by ejecting droplets while moving the information of the powder 1 on the carriage 6 in which the plurality of ejection heads 5 are arranged with high accuracy. Further, since FIG. 1 shows a place where the powder 1 is smoothed while being supplied by the recoat roller 4, the carriage 6 is a place where the carriage 6 does not interfere with the recoat roller 4 and the powder supply unit 2 outside the modeling tank 3. I'm waiting at.

As the nozzle surface state detection unit 7 (an example of the nozzle surface observation unit), an optical camera device provided with a light source 8 can be used. The nozzle surface state detecting unit 7 is provided outside the modeling tank 3. Further, the nozzle surface state detection unit 7 detects droplets or powder 1 that becomes "dirt" that blocks the nozzle of the discharge head 5. When an optical camera device is used as the nozzle surface state detection unit 7, the nozzles of the discharge head 5 need to be magnified to some extent for observation, so that the field of view is narrowed and the states of all the nozzles of the discharge head 5 can be checked at once. It becomes difficult to take an image. Therefore, the discharge head 5 scans on the optical camera device (on the nozzle surface state detection unit 7) to observe the entire nozzle with a plurality of images.

However, the discharge head 5 may be imaged by a plurality of optical camera devices without scanning the discharge head 5, and the states of all the nozzles of the discharge head 5 may be observed based on the images captured by each optical camera device. ..

Further, as the nozzle surface state detecting unit 7, instead of the optical camera device, a device such as a laser displacement meter that three-dimensionally captures the shape of the nozzle surface may be used. Further, as the light source 8 provided together with the optical camera device, a light source that emits light having a wavelength that can distinguish the nozzle surface and the powder 1 may be used, or a light source that irradiates the nozzle surface with light at a predetermined angle. May be used.

Further, in order to capture the powder 1 adhering to the nozzle surface three-dimensionally with an optical camera device, a method of irradiating and observing a striped pattern of a plurality of widths can also be used.

(Hardware configuration)
Next, FIG. 4 is a block diagram showing a hardware configuration of the three-dimensional modeling apparatus of the first embodiment. In FIG. 4, the control unit 500 of the three-dimensional modeling apparatus 601 includes a CPU (Center Processing Unit) 501, a ROM (Read Only Memory) 502, a RAM (Random Access Memory) 503, and an NVRAM (Non Volatile Random Access Memory) 504. doing.

The CPU 501 controls the entire three-dimensional modeling device 601. The ROM 502 stores various programs such as a modeling program for causing the CPU 501 to execute three-dimensional modeling control, as well as fixed data and the like. Further, the ROM 502 stores a modeling program for realizing the observation operation of the nozzle surface of the discharge head 5 (the operation of the flowchart of FIG. 6), which will be described later.

The RAM 503 temporarily stores modeling data and the like. The NVRAM 504 is a non-volatile memory that retains data even when the power of the device is cut off. Mainly, the main control unit 500A is formed by the CPU 501, the ROM 502, and the RAM 503.

Further, the control unit 500 has an ASIC (Application Specific Integrated Circuit) 505 that processes input / output signals for controlling the entire device in addition to various signal processing performed on the image data. Further, the control unit 500 includes an external interface (external I / F) 506 for transmitting and receiving modeling data and the like to and from the modeling data creating device 600, which is an external device.

The modeling data creation device 600 is an device that creates modeling data by slicing a modeled object in the final form into each modeling layer, and is composed of an information processing device such as a personal computer device.

Further, the control unit 500 includes an input / output unit (I / O) 507 for capturing the detection signals of various sensors, and a head drive control unit 508 for driving and controlling each discharge head 5 of the liquid discharge unit 50. ..

The control unit 500 drives the motor drive unit 510 that drives the motor of the X-direction scanning mechanism 550 that moves the carriage 51 (= carriage 6) of the liquid discharge unit 50 in the X direction (main scanning direction), and the modeling unit 5 in the Y direction. It includes a motor drive unit 512 that drives the motor of the Y-direction scanning mechanism 552 that moves in the (sub-scanning direction).

Further, the control unit 500 includes a motor drive unit 511 that drives the motor of the Z-direction elevating mechanism 551 that moves (elevates) the carriage 51 (= carriage 6) of the liquid discharge unit 50 in the Z direction. The elevating and lowering in the arrow Z direction may be configured to elevate and lower the entire modeling unit 5.

The control unit 500 includes a motor drive unit 513 that drives the motor 27 that raises and lowers the supply stage 23, and a motor drive unit 514 that drives the motor 28 that raises and lowers the modeling table 24. Further, the control unit 500 includes a motor drive unit 515 that drives the motor 553 of the reciprocating movement mechanism 25 that moves the flattening roller 12, and a 516 that drives the motor 26 that rotationally drives the flattening roller 12.

Further, the control unit 500 includes a supply system drive unit 517 that drives the powder supply device 554 that supplies the powder 20 to the supply tank 21, and a maintenance drive unit 518 that drives the maintenance mechanism 61 of the liquid discharge unit 50. There is.

The I / O 507 of the control unit 500 is supplied with a detection signal indicating temperature and humidity as environmental conditions of the device detected by the temperature / humidity sensor 560, and is also supplied with detection signals of other sensors. Further, an operation panel 522 for inputting and displaying information necessary for this device is connected to the control unit 500.

The modeling data creation device 600 and the three-dimensional modeling device 601 constitute a three-dimensional modeling system.

(Functional configuration)
FIG. 5 is a functional block diagram of the three-dimensional modeling apparatus of the first embodiment. The CPU 501 shown in FIG. 4 executes a modeling program stored in a storage unit such as a ROM 502 to execute a stain amount analysis unit 101 (an example of a calculation unit and a nozzle surface stain amount analysis unit) and a stain amount analysis unit shown in FIG. Each function of the factor determination unit 102, the cleaning determination unit 103 (an example of the nozzle surface cleaning determination unit), the cleaning control unit 104 (an example of the cleaning control unit), the modeling control unit 105, and the notification control unit 106 is realized. The operation of each part 101 to 106 will be described later using the flowchart of FIG.

It was decided that each part 101-106 was realized by software by a modeling program. However, all or part of these may be realized by hardware such as an IC (Integrated Circuit).

Further, the modeling program may be provided by recording the file information in an installable format or an executable format on a recording medium readable by a computer device such as a CD-ROM or a flexible disk (FD). Further, the modeling program may be provided by recording on a recording medium readable by a computer device such as a CD-R, a DVD (Digital Versatile Disk), a Blu-ray (registered trademark) disk, or a semiconductor memory. Further, the modeling program may be provided in the form of being installed via a network such as the Internet. Further, the modeling program may be provided by incorporating it into a ROM or the like in the device in advance.

(Conditions under which powder can adhere to the nozzle surface)
Next, with reference to FIG. 3, the conditions under which the powder 1 can adhere to the nozzle surface due to the ejection of droplets will be described. FIG. 3 shows a state in which the discharge head 5 discharges droplets to the powder 1 in the modeling tank 3. Further, in order to explain the conditions under which the powder 1 can adhere to the nozzle surface of the discharge head 5 due to the discharge of the droplets, the place where the discharge head 5 discharges the droplets is shown enlarged.

Since it is desired to land the droplets on the powder 1 with high accuracy, the ejection distance of the droplets should have a certain speed or higher. This is because the actual velocity vector of the droplet is a vector in which the ejection velocity (Vj) of the droplet and the moving velocity (Vc) of the carriage 6 are related, so that the droplet flies in an oblique direction. .. As a result, an error occurs in the landing location of the droplet due to the velocity fluctuation of the carriage 6 and the deviation of the ejection GAP (Dt) between the nozzle surface of the ejection head 5 and the powder 1. The influence of the deviation (error) between the moving speed (Vc) of the carriage 6 and the ejection GAP (Dt) on the landing position is that the faster (larger) the ejection speed (Vj) of the droplet is, the smaller the influence is.

Further, the larger the ejection velocity (Vj) of the droplet, the shorter the time until landing, and the smaller the influence of the airflow (airflow is generated by the movement of the carriage 6 or the like) on the landing position. For the same reason, it is preferable that the discharge GAP (Dt) is also constant or less.

Further, since it is desired to improve the productivity (production speed) of laminating the powder 1 to form a modeled object, it is desired to increase the size of the droplets (Mj) by a certain amount or more. Further, the larger the size of the droplet (Mj), the smaller the influence of the airflow (the airflow is generated by the movement of the carriage 6 or the like) on the landing position.

Further, in order to increase the resolution (surface property or accuracy) of the modeled object, it is desired to keep the size (particle size) of the powder 1 below a certain level. Under such conditions, the powder 1 tends to adhere to the nozzle surface of the discharge head 5, which causes poor discharge of droplets and lowers the reliability of the discharge head 5.

The principle that the powder 1 adheres to the nozzle surface of the discharge head 5 by ejecting the droplets is as follows. That is, a part of the kinetic energy of the ejected droplets is attached to the nozzle surface of the ejection head 5 by repelling the powder 1 by the impact of the droplets.

Since the minimum energy required for the powder 1 to reach the nozzle surface is the gravitational potential energy between the discharge GAPs of the powder 1, if the configuration has the following inequality, the parameters constituting the following inequality There is a high possibility that some change has occurred in the controlled object that controls.

Therefore, by observing the change in the state of the powder 1 adhering to the nozzle surface, the factors that worsen (or improve) the dirt on the nozzle surface can be estimated, and the control of the unit can be corrected, maintained, or parts replaced. Cleaning frequency can be minimized by executing. In addition, deterioration of the modeled object can be prevented. Further, in addition to the ejected droplets repelling the powder 1, it is conceivable that the powder 1 adheres to the nozzle surface due to the air flow caused by the movement of the carriage 6, etc., but the influence of the contamination of the nozzle surface by the air flow is I know it's small.

Here, the kinetic energy of the droplet is represented by Mj × ((Vj ² + Vc ² ) / 2), and the potential energy due to gravity between the ejection GAPs of the ejection medium is “Dt × mass of the ejection medium ×”. It is represented by "g (gravitational acceleration)". Therefore, in the configuration where "Mj x ((Vj ² + Vc ² ) / 2)> Dt x mass of the ejected medium x g (gravitational acceleration)" is established, the field building where the observation result of the nozzle surface changes is It is possible that some change has occurred in the controlled object that controls the parameters that make up this inequality.

It will be explained in detail again. First, the controlled objects constituting the mass Mj of the ink droplet and the ejection speed Vj will be described. First, the viscosity of the ink is a control target that constitutes the mass Mj of the ink droplet and the ejection speed Vj. Ink viscosity is highly dependent on ink temperature. Generally, the higher the temperature, the lower the viscosity.

Specifically, the ink heater in the ejection head 5, the ink heater in the sub tank, the environmental temperature, and the like are controlled targets, and these temperature changes affect the ink temperature. When the ink temperature changes due to these controlled objects, the ink viscosity changes, and the mass Mj of the ink droplet and the ejection speed Vj change. What kind of change occurs in the high and low ink viscosity, the mass Mj of the ink droplet, and the ejection speed Vj depends on the type of the ejection head 5 and the ejection control.

However, these changes are clarified in advance because they are measured in advance at the time of designing the discharge performance of the discharge head 5. Therefore, it is easy to predict how the controlled object will change.

To give a specific example of a change in the control target, for example, the head temperature or the sub tank temperature is often controlled by measuring the temperature of a container or the like in contact with the ink, instead of directly measuring the ink temperature. In such a case, it is predicted that if the environmental temperature decreases, the ink temperature will be affected to some extent and decrease. Further, when the performance of the sub tank heater or the head heater changes due to deterioration with time or the like, it can be predicted in the same manner. As an example, the sub-tank temperature and the like have been described as an example, but even a device not provided with the sub-tank is effective for predicting a change in the control target for controlling the ink temperature.

Next, the control targets that affect the mass Mj of the ink droplets and the ejection speed Vj include volatilization of ink components, changes in ink quality, ink storage period, and deterioration of ejection performance of the ejection head 5 (number of uses and time). And so on. It is possible to predict changes in these as well as the ink temperature.

Here, in the three-dimensional modeling apparatus of the embodiment, there are a plurality of controlled objects constituting the mass Mj of the ink droplet and the ejection speed Vj. Therefore, a sensor for specifying the control target (for example, a sensor for measuring the environmental temperature) or the like is provided. Further, in the three-dimensional modeling apparatus of the embodiment, the control target is the sub tank heater by changing the heater temperature of the sub tank heater and the head heater or changing the printing amount to measure the discharge amount in the maintenance operation. Identifies whether it is a head heater or a head heater.

Next, an object constituting the moving speed of the carriage 6 will be described. The moving speed of the carriage 6 is generally measured directly by a sensor such as an encoder. Abnormal vibration may occur in the carriage 6 due to fluctuations in the carriage speed due to a sensing error due to dirt on the encoder sensor, dirt on the drive guide shaft of the carriage 6, or the like. As a result, the moving speed of the discharge head 5 may change.

Carriage speed fluctuations due to sensing errors due to dirt on the encoder sensor can be easily determined by counting the number of encoders during homing operation. Therefore, in the three-dimensional modeling apparatus of the embodiment, when there is a concern that the encoder is dirty due to the dirt on the nozzle surface of the discharge head 5, the number of encoders during the homing operation of the carriage 6 is counted, and the encoder sensor is dirty. Determine the carriage speed fluctuation due to a sensing error.

Further, in the three-dimensional modeling apparatus of the embodiment, abnormal vibration generated in the carriage 6 due to dirt on the drive guide shaft of the carriage 6 is directly sensed by an acceleration sensor or the like, or a specific pattern is printed and printed. Determine from the result.

Next, the target constituting the discharge gap (discharge GAP) will be described. The target constituting the discharge GAP includes a mounting deviation of the discharge head 5, a height deviation of the recording medium (powder surface), and the like. The discharge head 5 is designed to be within the permissible deviation if the mounting is normal. Therefore, the former head mounting deviation may be due to improper mounting. Also. Since the discharge head 5 is a replacement part, it is conceivable that the discharge head 5 is improperly attached by a user or a serviceman.

The three-dimensional modeling apparatus of the embodiment monitors the timing of head replacement and the timing of nozzle surface contamination, thereby improving the accuracy of predicting improper attachment of the discharge head 5.

On the other hand, the latter height deviation of the recorded medium (powder surface) includes a defect in any of the configurations for transporting the recorded medium, such as roller stains forming a flat surface of the recorded medium and abnormal vibration. Alternatively, it is conceivable that the physical properties of the recording medium to be transported are abnormal. In the case of a configuration in which powder is used as the recording medium, the powder is often (possibly) configured to reuse the unprinted portion. In such a case, the printed portion also has an element such as ink mist or satellite ink that changes the physical characteristics of the powder. It is conceivable that the powder surface of the powder cannot be made normally by reusing this powder. This defect can be predicted from the degree of dirt on the nozzle surface.

In this case, depending on the physical characteristics of the powder, the physical characteristics of the ink, or the configuration for transporting the powder, the nozzle surface often changes in the direction in which it does not become dirty. Therefore, in the three-dimensional modeling apparatus of the embodiment, by observing the nozzle surface, although the nozzle surface itself to be observed is not defective, defects such as changes in the physical properties of the powder are predicted.

Further, the mass of the recording medium can be measured and designed in advance. By associating with manufacturing information such as the lot number, it is possible to improve the accuracy of predicting the possibility that the mass of the powder changes due to the change in the dirt on the nozzle surface.

(Nozzle surface observation operation)
FIG. 6 is a flowchart showing the flow of the observation operation of the nozzle surface. Using the flowchart of FIG. 6, the user automatically improves the unit that controls the parameters that contribute to the adhesion of the discharged medium to the nozzle surface from the observation result of the discharge nozzle surface, or maintenance, etc. Alternatively, the operation for urging the service person to improve is explained.

The flowchart of FIG. 6 starts by observing the nozzle surface, and the process proceeds to step S1. The CPU 501 controls the nozzle surface state detection unit 7 so as to observe the nozzle surface while moving the powder 1 for modeling the modeled object. As a result, when the powder 1 is laid, the discharge head 5 is in a standby state, so that this time can be effectively used, and the inconvenience of reducing productivity can be prevented.

When the observation of the nozzle surface is executed, the dirt amount prayer unit 101 quantifies the degree of dirt on the nozzle surface. The stain factor determination unit 102 (an example of the determination unit) compares the value quantified by the stain amount analysis unit 101 with the stain amount expected from the past stain condition and discharge history, or the data stored in advance. By comparison, it is determined whether or not there is a change in the dirt on the nozzle surface by a certain amount or more (step S1). Alternatively, the dirt factor determination unit 102 determines whether there is a difference with respect to the comparison target.

If the dirt on the nozzle surface changes by a certain amount or more, or if there is no difference with respect to the comparison target (step S1: No), the process proceeds to step S6, and the cleaning determination unit 103 determines whether or not the nozzle surface needs to be cleaned. .. When cleaning is not required (step S6: No), the process of the flowchart of FIG. 6 is completed without cleaning the nozzle surface. On the other hand, when cleaning is required (step S6: Yes), the cleaning control unit 104 controls the nozzle cleaning mechanism so as to clean the nozzle surface (step S7), and the flowchart of FIG. 6 shows. End the process.

On the other hand, when the dirt on the nozzle surface changes by a certain amount or more or there is a difference with respect to the comparison target (step S1: Yes), the dirt troubler determination unit 102 estimates and estimates the cause of the dirt on the nozzle surface. It is determined whether or not the influence of the cause of dirt on the modeled object can be tolerated (step S2).

Specifically, the “unacceptable case” is, for example, a case where the nozzle surface of the discharge head 5 being observed is significantly contaminated with the recording medium (powder) as compared with the normal case. In this case, the discharge head 5 may have come into contact with the recording medium, and there is a high possibility that a large error has occurred in the shape of the modeled object. Then, it can be presumed that the cause is in the transport portion of the recording medium.

Further, when the nozzle surface of the ejection head 5 being observed is significantly contaminated with ink, the meniscus on the liquid surface of the ejection nozzle 5 is damaged, or the pressure balance (usually negative pressure) in the ejection head 5 is broken. It is conceivable that the ink oozes out from the nozzle and drips unintentionally (other than the ejection operation). In this case as well, there is a high possibility that a large error has occurred in the shape of the modeled object, and it can be presumed that the cause is the pressure control unit or the cleaning unit of the discharge head 5.

Further, the adhesion of the recording medium (powder) to the nozzle surface of the ejection head 5 being observed is significantly less than in the normal state, but when the ink is normally adhered, the recording medium is normally conveyed. There is a high possibility that there is no such thing, and there is a high possibility that there is a large error in the shape of the modeled object. Then, it can be presumed that the cause is in the transport portion of the recording medium.

Further, if neither the ink nor the recording medium (powder) adheres to the nozzle surface of the ejection head 5 being observed, it is highly possible that the ink is not ejected normally. In this case as well, there is a high possibility that a large error has occurred in the shape of the modeled object.

Since the extent to which such a significant change can be tolerated changes depending on the recording medium or ink ejection, it is preferable to appropriately design the system. In such a case, by stopping the modeling, it is possible to quickly recover from the modeling failure and minimize the waste of the modeling material.

Next, when the influence on the modeled object cannot be tolerated (step S2: No), the modeling control unit 105 (an example of the control unit) controls the modeling unit 1 so as to stop modeling as a modeling error (step S8). .. In this case, the notification control unit 106 displays and controls, for example, an error message indicating that the modeling has been forcibly stopped on the operation panel 522 (step S9). It should be noted that the notification by such an error message or the like may be performed by voice, vibration or the like.

In this way, by stopping the modeling when the influence on the modeled object cannot be tolerated, it is possible to save the modeling material and the time required for modeling.

Next, when it is determined that the influence on the modeled object is acceptable (step S2: Yes), the process proceeds to step S3, and can the effect on the modeled object by the stain factor determination unit 102 be improved during the modeling? Determine if not. When it is determined that the influence on the modeled object cannot be improved during modeling (step S3: No), the modeling control unit 105 controls the control target so that the effect can be improved, or the notification control unit 106 determines. An improvement plan that can improve the influence is displayed and controlled on the operation panel 522 (step S10).

It should be noted that the notification of such an improvement plan may be given by voice or the like. After executing or notifying such an improvement plan, the cleaning determination unit 103 determines in step S6 whether or not the nozzle needs to be cleaned, and if necessary, controls the cleaning control unit 104 in step S7. The nozzle is cleaned. The cleaning control unit 104 controls the cleaning mechanism so as to clean the nozzle surface while moving the powder 1 for modeling the three-dimensional modeled object. As a result, the waiting time of the discharge head 5 can be effectively used to clean the nozzle, and the productivity of the three-dimensional model can be improved.

On the other hand, when it is determined that the influence on the modeled object can be improved during modeling (step S3: Yes), the modeling control unit 105 controls the object to improve the effect while modeling the modeled object. Is controlled (step S4). Then, the cleaning control unit 104 cleans the nozzle surface (step S5), and ends the process shown in the flowchart of FIG.

If it is determined that improvement cannot be made during modeling, the improvement plan may be executed after the modeling is completed, or a notification for urging the user or service to improve may be executed.

Here, whether or not the influence of the modeling control unit 105 can be improved depends on whether or not the controlled object has an automatic improvement mechanism. Therefore, it can be appropriately designed according to the purpose and specifications of the device. For example, when the transporting unit of the recorded medium has a transporting section cleaning mechanism for the recording medium and some trouble is presumed in the transporting section of the recorded medium, the modeling control unit 105 cleans the transporting section. By executing it, try to improve the problem. If the effect is not improved even after cleaning the transport unit, the notification control unit 106 gives a notification indicating that there is a sign of failure of the transport unit after the modeling is completed. As a result, the user or the maintenance man can be urged to perform repairs such as inspection or parts replacement.

Further, although the adhesion of the ink and the recording medium (powder) to the nozzle surface of the ejection head 5 being observed is within the permissible range, a change may be observed. One of the causes of this is that skipping occurs due to ink mist or powder adhering to the encoder that monitors the speed of the carriage 6. When the skipped reading of this encoder occurs, the sensing interval becomes wider according to the skipped section, and the wide section is controlled at a constant speed. Therefore, the speed of the carriage 6 becomes faster or the carriage 6 exhibits a vibration operation. become. Due to this effect, the speed of the ink droplets also changes, and the amount of ink and the recording medium (powder) adhered to the nozzle surface of the ejection head 5 being observed changes. Ink and recording medium (powder) are examples of "adhesions". Since the encoder of the carriage 6 is not usually provided with a cleaning mechanism, if the encoder skips, parts replacement is an improvement measure. Therefore, the notification control unit 106 gives a notification indicating that there is a sign of failure in the transport unit after the modeling is completed. As a result, the user or the maintenance man can be urged to perform repairs such as inspection or parts replacement.

(Effect of the first embodiment)
As is clear from the above description, the three-dimensional modeling apparatus of the first embodiment determines the amount of deposits (ink, powder, etc.) adhered to the nozzle surface based on the observation result of the nozzle surface of the discharge head 5. calculate. Then, based on the calculation result of the amount of the adhered matter, the operation with respect to the control target that controls at least one of the mass of the ink (droplet) and the ejection speed is determined.

As a result, it is possible to estimate the factors that worsen (or improve) the dirt on the nozzle surface, correct the control of the unit, perform maintenance, replace parts, and the like. Therefore, the frequency of cleaning the discharge head 5 can be suppressed to a low frequency, and the productivity of the modeled object can be improved. In addition, the durability of the water-repellent film of the nozzle can be improved.

Further, by increasing the frequency of cleaning the nozzle surface of the discharge head 5, it is possible to prevent the inconvenience that the productivity of the modeled object is lowered and the durability of the water-repellent film of the nozzle is impaired. Further, the frequency of cleaning the nozzle surface of the discharge head 5 can be reduced, and deterioration of the modeled object can be prevented.

[Second Embodiment]
Next, the three-dimensional modeling apparatus of the second embodiment will be described. The amount of ink adhered and the amount of powder adhered on the nozzle surface of the ejection head 5 are different from each other. Therefore, in the three-dimensional modeling apparatus of the second embodiment, the amount of ink adhered to the ejection head 5 and the amount of powder adhered to the ejection head 5 based on the captured image obtained by imaging the nozzle surface of the ejection head 5 by the nozzle surface state detecting unit 7. Is separately grasped by the prayer section 101 for the amount of dirt. As a result, cleaning of the discharge head 5 can be performed more efficiently and at a more optimal timing.

The three-dimensional modeling apparatus of the second embodiment has the same configuration and operational effects as those of the first embodiment described above, except that the amount of ink adhered and the amount of powder adhered are separately predicted. .. Therefore, hereinafter, only the difference between the two will be explained, and the duplicate explanation will be omitted.

(Hardware configuration of the second embodiment)
In the case of the three-dimensional modeling apparatus of the second embodiment, the light source driving unit 520 and the light source 8 shown by the dotted line blocks in FIG. 4 are provided together with the parts described with reference to FIG. The light source 8 includes an ink detection light source 8a for ink detection and a powder detection light source 8b for powder detection.

The ink detection light source 8a and the powder detection light source 8b have different wavelengths, and for example, ultraviolet light, visible light, infrared light, or the like can be used. The ink detection light source 8a and the powder detection light source 8b irradiate the nozzle surface of the ejection head 5 with the ink detection light or the powder detection light vertically downward. Alternatively, the ink detection light source 8a and the powder detection light source 8b irradiate the nozzle surface of the ejection head 5 with ink detection light or powder detection light from an oblique direction at a predetermined angle.

The ink and powder adhering to the nozzle surface of the ejection head 5 may or may not show edge contrast as an image depending on the emitted light. The three-dimensional modeling apparatus of the second embodiment selects the wavelength at which the edge contrast is most emphasized as an image for the ink and the powder, thereby selecting the wavelength for each of the ink and the powder based on the image. Distinguish (separate) and recognize.

(Functional configuration)
In the case of the three-dimensional modeling apparatus of the second embodiment, the CPU 501 shown in FIG. 4 executes a modeling program stored in a storage unit such as ROM 502, together with each function described with reference to FIG. In FIG. 5, it has a light source drive control unit 7 shown by a dotted line block. The light source drive control unit 7 controls the light emission drive of the ink detection light source 8a and the powder detection light source 8b via the light source drive unit 520 shown in FIG.

(Nozzle surface observation operation)
FIG. 7 is a flowchart showing the flow of the observation operation of the nozzle surface in the second embodiment. The flowchart of FIG. 7 starts when the observation of the nozzle surface is started, and the process proceeds to step S11. In step S1, the light source drive control unit 107 shown in FIG. 5 simultaneously lights (or blinks) the ink detection light source 8a and the powder detection light source 8b via the light source drive unit 520. The ink detection light source 8a and the powder detection light source 8b may be lighting-controlled (or blinking-controlled) with a predetermined time difference.

FIG. 8 is a diagram showing a nozzle surface of the ejection head 5 in a state where the ink detection light from the ink detection light source 8a and the powder detection light from the powder detection light source 8b are irradiated. The ink detection light is light having a wavelength that emphasizes the contrast of the edge of the ink 701 adhering to the nozzle surface in the captured image obtained by capturing the nozzle surface. Further, the detection light for powder is light having a wavelength that emphasizes the contrast of the edge of the powder 702 adhering to the nozzle surface in the captured image obtained by capturing the nozzle surface. Therefore, as shown in FIG. 8, the ink 701 and the powder 702 can be clearly distinguished and recognized based on the captured image obtained by capturing the nozzle surface.

That is, the nozzle state detection unit 7 images the nozzle surface irradiated with the ink detection light and the powder detection light in this way (step S12). The dirt amount analysis unit 101 clearly distinguishes (separates) and recognizes the ink and powder adhering to the nozzle surface based on the captured image of the nozzle surface imaged by the nozzle state detection unit 7. Then, the dirt amount analysis unit 101 separates the ink 701 and the powder 702 adhering to the nozzle surface and quantifies each of them (step S13).

Next, the fouling factor determination unit 102 compares the value of the powder 702 quantified by the fouling amount analysis unit 101 with the fouling amount of the powder 702 predicted from the fouling condition by the past powder and the discharge history. Or, by comparing with the data stored in advance, it is determined whether or not there is a change of a certain amount or more (change of a threshold value or more) in the dirt due to the powder on the nozzle surface (step S14).

When it is determined that there is a change of a certain amount or more in the dirt caused by the powder on the nozzle surface (step S14: No), the cleaning control unit 104 controls the nozzle cleaning mechanism so as to clean the nozzle surface (step S14: No). S16). After this, the process returns to step S12.

On the other hand, when it is determined that the stain on the nozzle surface due to the powder does not change beyond a certain level (step S14: Yes), the stain factor determination unit 102 sets the value of the ink 701 quantified by the stain amount analysis unit 101. , Comparison with the amount of ink 701 stains expected from the past ink 701 stains and ejection history, or comparison with pre-stored data, changes in the ink 701 stains on the nozzle surface by a certain amount or more (threshold) It is determined whether or not there is (the above change) (step S15).

When it is determined that there is a change of a certain amount or more in the stain on the nozzle surface due to the ink 701 (step S15: No), the cleaning control unit 104 controls the nozzle cleaning mechanism so as to clean the nozzle surface (step S15: No). S16). After this, the process returns to step S12.

When it is determined that the stain on the nozzle surface by the ink 701 does not change more than a certain level (step S15: Yes), it means that the stain on the nozzle surface by the powder 702 and the ink 701 is less than or equal to the predetermined value. , The processing of the flowchart of FIG. 7 is terminated as it is.

(Effect of the second embodiment)
As is clear from the above description, the three-dimensional modeling apparatus of the second embodiment is divided into ink 701 and powder 702, recognizes dirt on the nozzle surface, and determines the presence or absence of cleaning. As a result, cleaning of the discharge head 5 can be performed more efficiently and at a more optimal timing, and the same effect as that of the first embodiment described above can be obtained.

(Modification example)
The second embodiment described above is an example in which the ink detection light source 8a and the powder detection light source 8b that irradiate the ink detection light or the powder detection light are used as the light source 8. However, a light source 8 that irradiates the nozzle surface of the discharge head 5 with a predetermined pattern light such as a striped pattern may be used.

FIG. 9 is a diagram showing a state in which the nozzle surface of the discharge head 5 is irradiated with the striped pattern light from the light source 8. As the pattern light, ultraviolet light, visible light, infrared light, or the like can be used. Further, the pattern light may be irradiated vertically downward with respect to the nozzle surface of the discharge head 5, or may be irradiated from an oblique direction at a predetermined angle.

In this case, as shown in FIG. 9, the unevenness of the ink 701 and the powder 702 adhering to the nozzle surface of the ejection head 5 is emphasized by the striped pattern light. The ink 701 and the powder 702 in a state where the unevenness is emphasized are imaged by the nozzle surface state detection unit 7. The stain amount analysis unit 10 and the stain factor determination unit 102 can separate and recognize the ink 701 and the powder 702 based on the captured image captured by the nozzle surface state detection unit 7, and the ejection head 5 can be recognized in the same manner as described above. Cleaning can be performed more efficiently and at a more optimal timing.

Finally, the embodiments described above are presented as an example and are not intended to limit the scope of the invention. This novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. Further, the embodiment and the modification of the embodiment are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and the equivalent scope thereof.

1 Powder 2 Powder supply unit 3 Modeling tank 4 Recoat roller 5 Discharge head 6 Carriage 7 Nozzle surface condition detection unit 8 Light source 8a Ink detection light source 8b Powder detection light source 9 Surplus powder receiving tank 10 Modeling plate 101 Dirt amount analysis unit 102 Dirt factor judgment unit 103 Cleaning judgment unit 104 Cleaning control unit 105 Modeling control unit 106 Notification control unit 107 Light source drive control unit 501 CPU
508 Head drive control unit 520 Light source drive unit 701 Ink 702 Powder

Japanese Unexamined Patent Publication No. 2008-132786

Claims (9)

A discharge head that discharges droplets through a nozzle to a discharge medium formed of powder,
A nozzle surface observing unit for observing the nozzle surface of the nozzle of the discharge head,
A calculation unit that calculates the amount of deposits adhering to the nozzle surface based on the observation results of the nozzle surface observation unit.
Based on the calculation result of the calculation unit, a determination unit that determines the operation of the control target that controls at least one of the mass and the ejection speed of the droplet, and a determination unit.
Droplet ejection device with. A cleaning control unit that controls a cleaning unit that cleans the nozzle surface,
A nozzle surface dirt amount analysis unit for quantifying the amount of deposits adhering to the ejected medium based on the observation result of the nozzle surface observation unit is provided.
The cleaning control unit includes a nozzle surface cleaning determination unit that determines whether or not to clean the nozzle surface based on a value quantified by the nozzle surface contamination amount analysis unit. The droplet ejection device according to. A stain change determination unit for determining whether or not there is a change in the nozzle surface stain based on the value quantified by the nozzle surface stain amount analysis unit is provided.
The droplet ejection device according to claim 2, wherein the nozzle surface cleaning determination unit determines whether or not to clean the nozzle surface based on the determination result of the stain change determination unit. A stain factor estimation unit that estimates the cause of stains based on the determination result of the stain change determination unit,
When the factor estimated by the fouling factor estimation unit is an unacceptable factor for the quality of the ejected medium, the ejection head is controlled so as to stop the ejection operation of the droplet to the ejected medium. The droplet ejection device according to claim 3, further comprising a control unit for the operation. When the factor estimated by the fouling factor estimation unit includes a factor that can be improved during the modeling of the discharge medium, the control unit can improve the factor while modeling the discharge medium. The droplet ejection device according to claim 4, wherein the controlled object is controlled so as to improve the above. A second aspect of the present invention, wherein the cleaning control unit controls the cleaning unit so as to clean the nozzle surface while the powder forming the discharge medium is being moved. 5. The droplet ejection device according to any one of 5. Any one of claims 1 to 6, wherein the nozzle surface observing unit observes the nozzle surface while moving the powder forming the discharge medium. The droplet ejection device according to the section. A nozzle surface observation step in which the nozzle surface observation unit observes the nozzle surface of the nozzle of the ejection head that ejects droplets through the nozzle to the ejected medium formed of powder.
A calculation step in which the calculation unit calculates the amount of deposits adhering to the nozzle surface based on the observation result of the nozzle surface observation unit.
A determination step in which the determination unit determines an operation with respect to a control target that controls at least one of the mass and the ejection speed of the droplet based on the calculation result of the calculation unit.
Droplet ejection method having. Computer,
A nozzle surface observation unit for observing the nozzle surface of the nozzle of the ejection head that ejects droplets through the nozzle to the ejected medium formed of powder.
A calculation unit that calculates the amount of deposits adhering to the nozzle surface based on the observation results of the nozzle surface observation unit.
A modeling program characterized in that it functions as a determination unit for determining an operation with respect to a controlled object that controls at least one of the mass and the ejection speed of the droplet based on the calculation result of the calculation unit.

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