WO2004076184A1

WO2004076184A1 - Liquid drop ejector

Info

Publication number: WO2004076184A1
Application number: PCT/JP2004/002405
Authority: WO
Inventors: Koji Higuchi; Osamu Shinkawa; Yusuke Sakagami
Original assignee: Seiko Epson Corporation
Priority date: 2003-02-28
Filing date: 2004-02-27
Publication date: 2004-09-10

Abstract

A liquid drop ejector in which appropriate recovery processing can be carried out readily and surely in recovery processing of a liquid drop ejection head when power is turned on. The liquid drop ejector comprises a plurality of liquid drop ejection heads each having an actuator being driven through a drive circuit, and a diaphragm being displaced through driving of the actuator to eject liquid in the cavity from a nozzle in the form of a liquid drop, characterized in that a means for detecting residual oscillation of the diaphragm at least when power is turned on, detecting abnormal ejection of the liquid drop ejection head based on the oscillation pattern of residual oscillation of the diaphragm thus detected and determining a recovery processing for eliminating abnormal ejection, and a means performing a recovery processing thus determined are provided.

Description

Technical field of droplet discharge device

The present invention relates to a droplet discharge device. Light

Background art

In an ink jet recording apparatus, which is one of the droplet ejection apparatuses, if the apparatus is left for a long time without printing, the solvent of ink (eg, water-soluble ink) passing through the ejection holes of the recording head is used. In this case, the viscosity of the ink increases due to the evaporation of water (hereinafter, also referred to as “thickened ink”), or the air is mixed in the ink supply system and the growth of fine bubbles originally in the ink causes May generate relatively large bubbles. If such an increase in the ink viscosity or the generation of bubbles occurs in the ink flow path communicating with the ejection holes of the recording head, the ejection from the recording head is performed normally even if the power is turned on again and printing is performed. Gone. In order to deal with ejection failures due to such causes, the ink jet recording apparatus employs, for example, a capping method that covers the ejection hole surface of the recording head to prevent the viscosity of the ink from increasing, and a pump or the like that pumps ink from the ejection holes in this capping state. Recovery processing such as pump suction for discharging the thickened ink by suction or flushing for discharging the thick ink and discharging the thickened ink to a predetermined ink receiver formed of an ink absorber or the like is performed. '

The conventional inkjet recording apparatus automatically performs a predetermined recovery operation combining the above-described recovery processing when the power is turned on next time, or the recording apparatus performs the above-described recovery operation as needed by an operator. Was instructed to execute.

However, when the above-mentioned recovery operation is performed automatically, for example, When using equipment that repeatedly turns the power on and off, the leaving time is relatively short, so it is not always necessary to perform the recovery operation every time the power is turned on. In such a case, there is a problem that ink is unnecessarily consumed.

On the other hand, when the recovery operation is performed according to the operator's judgment, a test pattern is first discharged onto an ink receiver (for example, paper), and the operator visually checks whether or not there is a discharge failure. However, there is a problem that the operation is wasted, and the operator needs to have knowledge about the discharge failure, and the handling becomes troublesome.

In view of these problems, as a method of minimizing wasteful consumption of ink and preventing ejection failure, according to the elapsed time from when the power of the inkjet recording apparatus is turned off to when the power is turned on again. A method has been proposed in which a recovery operation is performed by changing the recovery conditions (flashing, pump suction) of the recording head (for example, Japanese Patent Application Laid-Open No. Hei 6-122006).

However, the ink tends to thicken during low-temperature drying, and conversely hardly thickens during high-temperature wetting, and the required amount of the recovery treatment with the lapse of time varies greatly depending on the environment. In the methods described above, since there is no means to detect such environmental effects, the recovery process must be set with safety in mind, and ink may be ejected more than necessary. Economy. In addition, whether or not all the nozzles related to ink ejection have recovered normally by the recovery process must be visually judged by the operator after all, and the result of output to paper or the like must be judged visually. Did not. In addition, since timekeeping means is essential, the number of components increases, which also causes cost increases. Disclosure of the invention

An object of the present invention is to provide a process for recovering a droplet discharge head upon turning on a power supply. An object of the present invention is to provide a droplet discharge device that can easily and surely perform an appropriate recovery process.

Such an object is achieved by the present invention described below.

A droplet discharge device according to the present invention includes an actuator driven by a driving circuit, and a diaphragm that is displaced by the driving of the actuator, driving the actuator by the driving circuit, and A plurality of droplet ejection heads for ejecting the liquid from the nozzle as droplets, comprising:

At least when power is turned on, a residual vibration of the diaphragm is detected, and a discharge abnormality of the droplet discharge head is detected based on the detected vibration pattern of the residual vibration of the diaphragm. A discharge abnormality detection / recovery process determining means for determining a recovery process for eliminating the discharge abnormality;

Recovery means for executing the recovery processing determined by the discharge abnormality detection / recovery processing determination means.

In the droplet discharge apparatus according to the present invention, the discharge abnormality detection / recovery processing determining means includes a vibration pattern of the residual vibration of the diaphragm when the actuator is driven to such an extent that the drive circuit does not discharge droplets. Based on the above, it is preferable to detect an abnormal discharge of the droplet discharge head and determine a recovery process for eliminating the abnormal discharge.

In the droplet discharge device of the present invention, the discharge abnormality detection / recovery processing determining means has a function of detecting a cause of the discharge abnormality of the droplet discharge head based on the vibration pattern of the residual vibration of the diaphragm. Is preferred.

In the droplet discharge apparatus of the present invention, the discharge abnormality detection / recovery processing determining means, when the discharge abnormality of the droplet discharge head is detected, detects the discharge abnormality of the droplet discharge head. It is preferable to determine a recovery process for eliminating the cause of the discharge abnormality according to the cause of the above.

In the droplet discharge device according to the aspect of the invention, the recovery unit may include a nozzle of the droplet discharge head. A wiping means for wiping the nozzle surface on which the nozzles are arranged with a wiper, and a flushing processing for driving the actuator and preliminary discharging the droplets from the nozzles of the droplet discharge head. It is preferable to include a flushing unit and a pumping unit that performs a pump suction process by a pump connected to a cap that covers a nozzle surface of the droplet discharge head.

In the droplet discharge device of the present invention, the discharge abnormality detection / recovery processing determining means, when it is determined that the cause of the discharge abnormality of the droplet discharge head is mixing of bubbles into the cavity, It is preferable to select the pump suction process as the recovery process for eliminating the discharge abnormality.

In the droplet discharge device of the present invention, the discharge abnormality detection / recovery processing determining means determines that the cause of the discharge abnormality of the droplet discharge head is that paper powder has adhered to the vicinity of the nozzle outlet. In this case, it is preferable to select at least the wiping process as the recovery process for eliminating the discharge abnormality.

In the droplet ejection apparatus of the present invention, the ejection abnormality detection / recovery processing determining means determines that the cause of the ejection abnormality of the droplet ejection head is that the liquid near the nozzle has thickened due to drying. Preferably, the flushing process or the pump suction process is selected as the recovery process for eliminating the discharge abnormality. In the droplet ejection apparatus of the present invention, the ejection abnormality detection / recovery processing determining means determines that the cause of the ejection abnormality of the droplet ejection head is that the liquid near the nozzle has thickened due to drying. Preferably, the flushing process is selected as a recovery process for eliminating the discharge abnormality.

In the droplet discharge apparatus according to the present invention, the discharge abnormality detection / recovery processing determining means includes a recovery processing for eliminating the discharge abnormality when the discharge abnormality is not resolved even after performing the flushing processing by the flushing means a predetermined number of times. Preferably, the pump suction process is selected.

In the droplet discharge device of the present invention, the pump suction processing by the If the discharge abnormality is not solved even after performing the predetermined number of times, it is preferable to have a notifying means for notifying the information.

In the droplet discharge device according to the aspect of the invention, it is preferable that the vibration pattern of the residual vibration of the diaphragm include the period of the residual vibration.

In the droplet discharge device of the present invention, the discharge abnormality detection / recovery process determining means may include a device in which bubbles are mixed in the cavity when the cycle of the residual vibration of the diaphragm is shorter than a cycle of a predetermined range. When the period of the residual vibration of the diaphragm is longer than a predetermined threshold value, it is determined that the liquid near the nozzle has increased in viscosity due to drying, and the period of the residual vibration of the diaphragm is the predetermined period. If the period is longer than the period of the range and shorter than the predetermined threshold, it is preferable to determine that paper dust has adhered near the outlet of the nozzle.

In the droplet discharge device of the present invention, the discharge abnormality detection / recovery processing determining means includes a vibration circuit, and the oscillation circuit oscillates based on a capacitance component that changes due to residual vibration of the vibration plate. Is preferred.

In the droplet discharge apparatus of the present invention, the discharge abnormality detection / recovery processing determining means includes a vibration circuit, and the oscillation is performed based on a capacitance component of the actuator that changes due to residual vibration of the vibration plate. Preferably, the circuit oscillates.

In the droplet discharge device according to the aspect of the invention, it is preferable that the oscillation circuit forms a CR oscillation circuit including a capacitance component of the actuator and a resistance component of a resistance element connected to the actuator.

In the droplet discharge device according to the present invention, the discharge abnormality detection / recovery processing determining means may include a residual vibration of the vibration plate based on a predetermined signal group generated based on a change in the oscillation frequency of the output signal of the oscillation circuit. It is preferable to include an FZV conversion circuit that generates a voltage waveform of

In the droplet discharge device according to the present invention, the discharge abnormality detection / recovery processing determining means includes a voltage waveform of the residual vibration of the diaphragm generated by the FZV conversion circuit. It is preferable to include a waveform shaping circuit for shaping into a constant waveform.

In the droplet discharge device of the present invention, the waveform shaping circuit removes a DC component from a voltage waveform of the residual vibration of the diaphragm generated by the F / V conversion circuit, and a DC component removing unit. A comparator for comparing the voltage waveform from which the DC component has been removed by the removing means with a predetermined voltage value, wherein the comparator generates and outputs a rectangular wave based on the voltage comparison; preferable.

In the droplet discharge apparatus of the present invention, the discharge abnormality detection / recovery processing determining means includes a measuring means for measuring a period of a residual vibration of the diaphragm from the rectangular wave generated by the waveform shaping circuit. preferable.

In the droplet discharge apparatus according to the aspect of the invention, the measuring unit includes a counter, and the counter counts a pulse of a reference signal, thereby detecting a pulse between rising edges of the rectangular wave or a rising edge and a falling edge. It is preferable to measure the time between edges.

In the droplet discharge device according to the aspect of the invention, it is preferable that the actuating unit is an electrostatic actuating unit.

In the droplet discharge device of the present invention, it is preferable that the actuator is a piezoelectric actuator utilizing a piezo effect of a piezoelectric element.

In the droplet discharge device of the present invention, it is preferable that the actuating unit is a film boiling type actuating unit having a heating element that generates heat when energized.

In the droplet discharge device according to the aspect of the invention, it is preferable that the diaphragm elastically deforms following a change in pressure in the cavity.

The droplet discharge device according to the present invention includes a storage unit that stores a cause of the discharge abnormality detected by the discharge abnormality detection / recovery process determining unit in association with a droplet discharge head to be detected. Is preferred.

In the droplet discharge device of the present invention, it is preferable that the droplet discharge device includes an ink jet printer. BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other objects, features and advantages of the invention will be more readily apparent from the following detailed description of a preferred embodiment of the invention which proceeds with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing the configuration of an ink jet printer, which is one type of the droplet discharge device of the present invention.

FIG. 2 is a block diagram schematically showing a main part of an ink jet printing apparatus according to the present invention.

FIG. 3 is a schematic sectional view of the head unit (inkjet head) shown in FIG. ·

FIG. 4 is an exploded perspective view showing the configuration of the head unit of FIG.

FIG. 5 is an example of a nozzle arrangement pattern of a nozzle plate of a head unit using a four-color ink.

FIG. 6 is a state diagram showing each state when a drive signal is input in a section taken along the line I-II in FIG.

FIG. 7 is a circuit diagram showing a simple vibration calculation model assuming residual vibration of the diaphragm of FIG.

FIG. 8 is a graph showing the relationship between the experimental value and the calculated value of the residual vibration of the diaphragm shown in FIG.

FIG. 9 is a conceptual diagram of the vicinity of the nozzle when bubbles are mixed in the cavity of FIG.

FIG. 10 is a graph showing calculated values and experimental values of residual vibration in a state where ink droplets are not ejected due to air bubbles entering the cavity.

FIG. 11 is a conceptual diagram of the vicinity of the nozzle when the ink near the nozzle of FIG. 3 is fixed by drying. ' FIG. 12 is a graph showing calculated values and experimental values of residual vibration in a state where the ink near the nozzles is in a dry and thickened state.

FIG. 13 is a conceptual diagram of the vicinity of the nozzle when paper dust adheres to the vicinity of the nozzle outlet of FIG.

FIG. 14 is a graph showing calculated values and experimental values of the residual vibration in a state where the paper dust adheres to the nozzle outlet.

FIG. 15 is a photograph showing the state of the nozzle before and after the paper dust adheres to the vicinity of the nozzle.

FIG. 16 is a schematic block diagram of the discharge abnormality detecting means shown in FIG. FIG. 17 is a conceptual diagram in the case where the electrostatic factor of FIG. 3 is a parallel plate capacitor.

FIG. 18 is a circuit diagram of an oscillation circuit including a capacitor composed of the electrostatic actuator shown in FIG.

FIG. 19 is a circuit diagram of the F / V conversion circuit of the discharge abnormality detecting means shown in FIG.

FIG. 20 is a timing chart showing the timing of the output signal of each unit based on the oscillation frequency output from the oscillation circuit.

FIG. 21 is a diagram for explaining a method of setting the fixed times tr and t1. FIG. 22 is a circuit diagram showing a circuit configuration of the waveform shaping circuit of FIG.

FIG. 23 is a block diagram schematically showing switching means for switching between the drive circuit and the detection circuit.

FIG. 24 is a flowchart showing a discharge abnormality detection / determination process.

FIG. 25 is a flowchart showing the residual vibration detection processing.

FIG. 26 is a flowchart showing the discharge abnormality determination process.

FIG. 27 shows an example of the timing of detecting a discharge abnormality of a plurality of inkjet heads (when there is one discharge abnormality detection means). Fig. 28 shows an example of the timing of detecting abnormal ejection of a plurality of ink jet heads (when the number of ejection abnormality detecting means is the same as the number of inkjet heads). This is an example of the timing of ejection failure detection (when the number of ejection failure detection means is the same as the number of ink jet heads and ejection failure detection is performed when print data is present). .

Fig. 30 shows an example of the timing of detecting abnormal discharge of a plurality of ink jet heads. (The number of abnormal discharge detection means is the same as the number of inkjet heads. Is performed).

FIG. 31 is a flowchart showing the timing of detecting a discharge abnormality during the flushing operation of the inkjet printer shown in FIG.

FIG. 32 is a flowchart showing the timing of detecting a discharge abnormality during the flushing operation of the inkjet printer shown in FIGS. 28 and 29. FIG. 33 is a flowchart showing the timing of detecting a discharge abnormality during the flushing operation of the ink jet printing shown in FIG.

FIG. 34 is a flowchart showing the timing of detecting an ejection failure during the printing operation of the ink jet printing shown in FIGS. 28 and 29.

FIG. 35 is a flowchart showing the timing of detection of a discharge abnormality during the printing operation of the ink jet printing shown in FIG.

FIG. 36 is a diagram showing a schematic structure (partially omitted) as viewed from above the ink jet printer shown in FIG.

FIG. 37 is a diagram showing a positional relationship between the wiper and the head unit shown in FIG.

FIG. 38 is a diagram showing the relationship between the head unit, the cap, and the pump during the pump suction process.

FIG. 39 is a schematic diagram showing the configuration of the tube pump shown in FIG. FIG. 40 is a flowchart showing an ejection failure recovery process in the ink jet printer of the present invention.

FIG. 41 is a flowchart showing a process at power-on in the ink jet printer of the present invention.

FIG. 42 is a flowchart showing a discharge abnormality determination process in the ink jet printer of the present invention.

FIG. 43 is a flowchart showing a discharge abnormality recovery process in the ink jet printer of the present invention.

FIG. 44 is a cross-sectional view schematically showing another configuration example of the ink jet head according to the present invention.

FIG. 45 is a cross-sectional view schematically showing another example of the configuration of the ink jet head according to the present invention.

FIG. 46 is a sectional view schematically showing another example of the configuration of the ink jet head according to the present invention.

FIG. 47 is a cross-sectional view schematically showing another configuration example of the inkjet head according to the present invention.

FIG. 48 is a perspective view showing another configuration example of the head unit in the present invention.

FIG. 49 is a schematic sectional view of the head unit shown in FIG.

FIG. 50 is a plan view showing an example of a nozzle arrangement pattern in a nozzle plate of a head unit using four-color inks. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the droplet discharge device of the present invention will be described in detail with reference to FIGS. This embodiment is given as an example, and the content of the present invention should not be limitedly interpreted. In the following, this embodiment In the embodiment, an ink jet printer that discharges ink (liquid material) and prints an image on a recording sheet will be described as an example of the droplet discharge device of the present invention.

FIG. 1 is a schematic diagram showing a configuration of an ink jet printing device 1 which is a kind of a droplet discharge device according to a first embodiment of the present invention. In the following description, the upper side in FIG. 1 is referred to as “upper”, and the lower side is referred to as “lower”.

Here, the main part (feature) of the present invention is processing at power-on (power-on). To facilitate understanding of the present invention, first, the configuration and operation (operation) of the inkjet printer 1 are described. Will be described in general, and then the processing at power-on will be described.

The ink jet printer 1 shown in Fig. 1 is equipped with the main unit 2, and has a tray 21 on which the recording paper P is placed at the upper rear, and a paper discharging roller 2 which discharges the recording paper P at the lower front. And an operation panel 7 on the upper surface.

The operation panel 7 includes, for example, a liquid crystal display, an organic EL display, an LED lamp, and the like. A display unit (display means) M for displaying an error message and the like, and an operation unit (not shown) including various switches, etc. ). The display section M of the operation panel 7 functions as a notification means.

In addition, a printing device (printing device) 4 having a reciprocating printing device (moving body) 3 and a paper feeder for supplying and discharging the recording paper P to the printing device 4 are mainly provided inside the device main body 2. It has a device (droplet receiving means) 5 and a control unit (control means) 6 for controlling the printing device 4 and the paper feeding device 5.

Under the control of the control unit 6, the paper feeding device 5 intermittently feeds the recording paper P one by one. This recording paper P passes near the lower part of the printing means 3. At this time, the printing means 3 reciprocates in a direction substantially perpendicular to the feeding direction of the recording paper P, and Printing on paper P is performed. That is, the reciprocating movement of the printing means 3 and the intermittent feeding of the recording paper P become the main scanning and the sub-scanning in the printing, and the ink jet printing is performed.

The printing device 4 receives the rotation of the printing means 3, a carriage motor 41 as a drive source for moving (reciprocating) the printing means 3 in the main scanning direction, and the carriage motor 41, and reciprocates the printing means 3. And a reciprocating mechanism 42 for moving. The printing means 3 includes a plurality of head units 35, an ink cartridge (IZC) 31 for supplying ink to each head unit 35, and a carriage equipped with each head unit 35 and an ink cartridge 31. 3 and 2. By using an ink cartridge 31 filled with four color inks of yellow, cyan, magenta, and black (black), full color printing can be performed. In this case, the printing means 3 is provided with a head unit 35 (this configuration will be described later in detail) corresponding to each color. Here, FIG. 1 shows four ink cartridges 31 corresponding to four color inks, but the head unit 35 has other colors, such as light cyan, light magenta, and dark yellow ink. It may be configured to further include the cartridge 31.

The reciprocating mechanism 42 has a carriage guide shaft 42 2 whose both ends are supported by a frame (not shown), and a timing belt 42 1 extending in parallel with the carriage guide shaft 42. ing.

The carriage 32 is reciprocally supported by a carriage guide shaft 42 of the reciprocating mechanism 42 and is fixed to a part of the evening belt 42 1.

When the timing belt 421 runs forward and backward via the pulleys by the operation of the carriage motor 421, the printing means 3 is reciprocated by being guided by the carriage guide shaft 422. The image data to be printed during this reciprocation In accordance with (print data), ink droplets are appropriately ejected from each inkjet head 100 of the head unit 35, and printing on the recording paper P is performed. The paper feeding device 5 has a paper feeding motor 51 serving as a driving source thereof, and a paper feeding roller 52 rotated by the operation of the paper feeding motor 51.

The paper feed roller 52 is composed of a driven roller 52a and a drive roller 52b, which are vertically opposed to each other across the recording paper P transport path (recording paper P), and the drive roller 52b is a paper feed motor. 5 Connected to 1. As a result, the paper feed roller 52 feeds a large number of recording papers P set in the tray 21 one by one toward the printing device 4 and discharges one by one from the printing device 4. I have. Note that, instead of the tray 21, a configuration may be adopted in which a paper cassette that stores the recording paper P can be detachably mounted.

The control unit 6 controls the printing device 4 and the paper feeding device 5 on the basis of print data input from a host computer 8 such as a personal computer (PC) or a digital camera (DC). Print processing is performed on P. Further, the control unit 6 displays an error message or the like on the display unit M of the operation panel 7 or turns on / flashes an LED lamp or the like, and also, based on various switch press signals input from the operation unit. The corresponding process is executed by each unit.

FIG. 2 is a block diagram schematically showing a main part of the ink jet printing of the present invention. In FIG. 2, an ink jet printer 1 of the present invention includes an interface section (IF: Interface) 9 for receiving print data and the like input from a host computer 8, a control section 6, and a carrier module 4. 1, a carriage motor driver 43 for driving and controlling the carriage motor 41, a paper supply motor 51, a paper supply motor driver 53 for driving and controlling the paper supply motor 51, and a head unit 3 5 A head driver 33 for driving and controlling the head unit 35; a discharge abnormality detecting means 10; a recovering means 24; and an operation panel 7. I can. The control unit 6 and the discharge abnormality detection means 10 constitute discharge abnormality detection and recovery processing determination means. The details of the ejection abnormality detection means 10, the recovery means 24, and the head driver 33 will be described later. .

In FIG. 2, the control unit 6 includes a CPU (Central Processing Unit) 61 that executes various processes such as a printing process and a discharge abnormality detection process, and print data input from the host computer 8 via the IF 9. (Electrically Erasable Programmable Read-Only Memory) (storage means) 62, which is a type of nonvolatile semiconductor memory that stores data in a data storage area (not shown). A RAM (Random Access Memory) 63 that temporarily stores data or temporarily expands application programs such as print processing, and a PROM that is a type of non-volatile semiconductor memory that stores control programs that control each unit. 64 and. The components of the control unit 6 are electrically connected via a bus (not shown).

As described above, the printing unit 3 includes the plurality of head units 35 corresponding to the respective color inks. Further, each head unit 35 includes a plurality of nozzles 110 and an electrostatic actuator 120 corresponding to each of the nozzles 110. That is, the head unit 35 is configured to include a plurality of ink jet heads 100 (droplet discharge heads) each having one set of nozzles 110 and an electrostatic work 120. I have. The head driver 33 comprises a drive circuit 18 for driving the electrostatic work 120 of each of the ink jet heads 100 to control the ink ejection timing, and a switching means 23. (See Figure 16). The configuration of the electrostatic actuator 120 will be described later.

Although not shown, the control unit 6 detects, for example, the remaining amount of ink in the ink cartridge 31, the position of the head unit 35, the printing environment such as temperature and humidity, and the like. Each possible sensor is electrically connected.

When the control unit 6 receives the print data from the host computer 8 via the IF 9, the control unit 6 stores the print data in the EEPROM 62. Then, the CPU 61 executes a predetermined process on the print data, and sends a drive signal to each of the drivers 33, 43, 53 based on the process data and input data from various sensors. Output. When these drive signals are input via the respective drivers 33, 43, 53, a plurality of electrostatic actuators 120 of the head unit 35, the carriage motors 41 of the printing device 4 and The paper feeder 5 operates. Thus, the printing process is performed on the recording paper P.

Next, the structure of each head unit 35 in the printing means 3 will be described. FIG. 3 is a schematic sectional view of the head unit 35 ′ (ink jet head 100) shown in FIG. 1, and FIG. 4 is a schematic configuration of the head unit 35 corresponding to one color ink. FIG. 5 is a plan view showing an example of a nozzle surface of the printing means 3 to which the head unit 35 shown in FIGS. 3 and 4 is applied. 3 and 4 are shown upside down from the state of normal use.

As shown in FIG. 3, the head unit 35 is connected to the ink cartridge 31 via an ink inlet 131, a damper chamber 130, and an ink supply tube 311. Here, the damper chamber 130 includes a damper 132 made of rubber. The damper chamber 130 absorbs ink fluctuations and changes in ink pressure when the carriage 32 reciprocates, thereby stably supplying a predetermined amount of ink to the head unit 35. In addition, the head unit 35 has a silicon nozzle plate 150 on the upper side with the silicon substrate 140 interposed therebetween, and a borosilicate glass substrate on the lower side with a coefficient of thermal expansion close to that of silicon. (Glass substrate) It has a three-layer structure in which 160 and 160 are laminated. The central silicon substrate 140 has several independent cavities (Pressure chamber) 1 4 1 (Figure 7 shows 7 cavities), 1 reservoir (common ink chamber) 1 4 3 and ink supply that connects this reservoir 1 4 3 to each cavity 1 4 1 Grooves functioning as mouths (orifices) 1 4 2 are formed. Each groove can be formed, for example, by performing an etching process from the surface of the silicon substrate 140. The nozzle plate 150, silicon substrate 140, and glass substrate 160 are joined in this order, and each cavity 144, reservoir 144, and ink supply port 142 are partitioned. It is formed.

Each of these cavities 141 is formed in a rectangular shape (a rectangular parallelepiped shape), and its volume is variable due to the vibration (displacement) of a diaphragm 121 described later. It is configured to eject ink (liquid material). In the nozzle plate 150, nozzles 110 are formed at positions corresponding to the front end portions of the cavities 141, and these are communicated with the cavities 141, respectively. Further, an ink inlet 131, which communicates with the reservoir 144, is formed in a portion of the glass substrate 160 where the reservoir 144 is located. Ink is supplied from the ink cartridge 3 1 to the ink supply tube

It is supplied to the reservoir 1 4 3 through the ink intake 1 3 1 through the 3 1 1 and the damper room 1 30. The ink supplied to reservoirs 1 4 3

Through 4 2, each of the independent cavities 1 4 1 is fed. Each cavity 14 1 consists of a nozzle plate 150, a side wall (partition wall) 144, and a bottom wall 1 2

A partition is formed by 1. -Each of the independent cavities 1 4 1 has its bottom wall 1 2 1 formed to be thin, and its bottom wall 1 2 1 is elastic in its out-of-plane direction (thickness direction), that is, in the vertical direction in FIG. It is configured to function as a diaphragm (diaphragm) that can be deformed (elastically displaced). Therefore, the bottom wall 121 may be referred to as a diaphragm 121 for convenience of the following description (ie, hereinafter, referred to as “ The symbol 1 2 1 is used for both the “bottom wall” and the “diaphragm”.

On the surface of the glass substrate 160 on the silicon substrate 140 side, shallow concave portions 161 are formed at positions corresponding to the cavities 141 of the silicon substrate 140, respectively. Therefore, the bottom wall 121 of each cavity 141 faces the surface of the opposite wall 162 of the glass substrate 160 in which the concave portion 161 is formed, with a predetermined gap therebetween. That is, a gap having a predetermined thickness (for example, about 0.2 μm) exists between the bottom wall 121 of the cavity 144 and a segment electrode 122 described later. The concave portion 161 can be formed by, for example, etching.

Here, the bottom wall (diaphragm) 1 2 1 of each cavity 1 4 1 is a common electrode 1 2 4 on the side of each cavity 1 4 1 for storing electric charge by the drive signal supplied from the head driver 3 3. Constitutes a part of. In other words, each of the diaphragms 121 of each of the cavities 14 1 also serves as one of the opposite electrodes (opposite electrodes of the capacitor) of the corresponding electrostatic factor 120 described later. Then, on the surface of the concave portion 16 1 of the glass substrate 16 0, the segment electrode is an electrode facing the common electrode 12 4 so as to face the bottom wall 12 1 of each cavity 14 1. 1 2 2 is formed. In addition, as shown in FIG. 3, the surface of the bottom wall 121 of each cavity 141 is covered with an insulating layer 123 made of a silicon oxide film (Si ₂ ). Thus, the bottom wall 1 2 1 of each cavity 1 4 1, that is, the diaphragm 1 2 1 and the corresponding segment electrodes 1 2 2 are represented by the bottom wall 1 2 1 of the cavity 1 4 1 in FIG. The counter electrode (counter electrode of the capacitor) is formed (configured) through the insulating layer 123 formed on the middle and lower surfaces and the void in the recess 161. Therefore, the main part of the electrostatic actuator 120 is constituted by the diaphragm 121, the segment electrode 122, the insulating layer 123 and the gap therebetween.

As shown in Fig. 3, a drive for applying a drive voltage between these counter electrodes The head dryno 33 including the driving circuit 18 performs charging and discharging between these counter electrodes in accordance with a print signal (print data) input from the control unit 6. One output terminal of the head driver (voltage applying means) 33 is connected to each segment electrode 122, and the other output terminal is connected to the common electrode 124 formed on the silicon substrate 140. Connected to input terminal 1 2 4a. Since the silicon substrate 140 has impurities implanted therein and has conductivity, the input terminal 124 a of the common electrode 124 and the common electrode 1 24 can be supplied with voltage. Further, for example, a thin film of a conductive material such as gold or copper may be formed on one surface of the silicon substrate 140. As a result, a voltage (charge) can be supplied to the common electrode 124 with low electric resistance (efficiently). This thin film may be formed by, for example, vapor deposition or sputtering. Here, in the present embodiment, for example, since the silicon substrate 140 and the glass substrate 160 are bonded (joined) by anodic bonding, a conductive film used as an electrode in the anodic bonding is formed on the silicon substrate 1. It is formed on the side of the flow channel formation surface 40 (the upper side of the silicon substrate 140 shown in FIG. 3). Then, this conductive film is used as it is as the input terminal 124 a of the common electrode 124. In the present invention, for example, the input terminal 124 a of the common electrode 124 may be omitted, and the bonding method between the silicon substrate 140 and the glass substrate 160 may be anodic bonding. Not limited. As shown in FIG. 4, the head unit 35 includes a nozzle plate 150 on which a plurality of nozzles 110 are formed, a plurality of cavities 144, a plurality of ink supply ports 144, and one reservoir. It comprises a silicon substrate (ink chamber substrate) 140 on which a bush 144 is formed, and an insulating layer 123, which are housed in a substrate 170 including a glass substrate 160. The base 170 is made of, for example, various resin materials, various metal materials, and the like, and the silicon substrate 140 is fixed and supported on the base 170.

Note that the nozzles 110 formed on the nozzle plate 150 are simplified in FIG. However, the nozzle arrangement pattern is not limited to this configuration, and is usually, for example, the nozzle arrangement pattern shown in FIG. So that they are staggered. Further, the pitch between the nozzles 110 can be appropriately set according to the printing resolution (dpi). FIG. 5 shows an arrangement pattern of the nozzles 110 when four color inks (ink cartridges 31) are applied.

FIG. 6 shows each state at the time of driving signal input in the III-III section of FIG. When a driving voltage is applied between the opposing electrodes from the head driver 33, a Coulomb force is generated between the opposing electrodes, and the bottom wall (diaphragm) 121 is moved from the initial state (Fig. 6 (a)). As a result, the segment electrode 122 bends to the side, and the capacity of the cavity 141 increases (FIG. 6 (b)). In this state, when the electric charge between the opposing electrodes is rapidly discharged under the control of the head driver 33, the diaphragm 121 recovers upward in the figure by its elastic restoring force, The diaphragm moves upward beyond the position of the diaphragm 121, and the volume of the cavity 141 contracts rapidly (Fig. 6 (c)). At this time, due to the compression pressure generated in the cavity 141, a part of the ink (liquid material) that satisfies the cavity 141 drops from the nozzle 110 communicating with the cavity 141. Is discharged.

The diaphragm 1 2 1 of each cavity 1 4 1 receives the next drive signal (drive voltage) by this series of operations (ink ejection operation by the drive signal of the head driver 33) and ejects ink droplets again. Until then, it is damping. Hereinafter, this damped vibration is also referred to as residual vibration. The residual vibration of the diaphragm 1 2 1 includes the acoustic resistance r due to the shape of the nozzle 110 and the ink supply port 144 or the ink viscosity, etc., the inertance m due to the ink weight in the flow path, and the diaphragm It is assumed that it has a natural vibration frequency determined by the compliance Cm of 121.

A calculation model for the residual vibration of diaphragm 1 2 1 based on the above assumptions will be described. . FIG. 7 is a circuit diagram showing a simple vibration calculation model assuming residual vibration of diaphragm 122. As described above, the calculation model of the residual vibration of the diaphragm 122 can be expressed by the sound pressure P, the inertance 1.1, the compliance Cm, and the acoustic resistance r. Then, when the step response when the sound pressure P is applied to the circuit in FIG. 7 is calculated for the volume velocity u, the following equation is obtained.

[Equation 1] p

U 'sin t (1) ω (2)

m 'C m

r

a (3)

2m The calculation result obtained from this equation is compared with the experimental result of the experiment on the residual vibration of the diaphragm 121 after the ejection of the ink droplet, which was performed separately. FIG. 8 is a graph showing the relationship between the experimental value and the calculated value of the residual vibration of diaphragm 122. As can be seen from the graph shown in Fig. 8, the two waveforms, the experimental value and the calculated value, generally match.

By the way, in each of the ink jet heads 100 of the head unit 35, a phenomenon that ink droplets are not normally ejected from the nozzle 110 despite the above-described ejection operation, that is, the ejection of droplets An error (head error) may occur. As described below, the causes of the discharge abnormality include (1) air bubbles entering the cavity 141, (2) drying and sticking of ink around the nozzle 110, and ( 3) Adhesion of paper powder near the nozzle 110 exit.

When this discharge abnormality occurs, the result is typically that of the nozzle 110 Droplets are not ejected from the nozzle, that is, a non-ejection phenomenon of droplets appears.

In the image printed (drawn) on the recording paper P, missing pixels of pixels occur. In addition, in the case of abnormal ejection, even if the droplet is ejected from the nozzle 110, the amount of the droplet is too small or the flight direction (trajectory) of the droplet is deviated. Since it does not land, it still appears as a missing pixel dot. For this reason, in the following description, the abnormal discharge of the droplet may be simply referred to as “missing dot”.

In addition, in the ejection failure of the ink jet head 100 (head failure), a phenomenon occurs in which ink droplets are not properly ejected from the nozzle 110 despite the ejection operation as described above. Not only the case but also the case where the ink droplets are not properly ejected from the nozzles 110 when the inkjet head 100 performs the above-described ejection operation is included.

In the following, on the basis of the comparison result shown in FIG. Adjust the values of acoustic resistance r and Z or inertance m so that the calculated value and the experimental value of the residual vibration of plate 1 21 match (approximately).

First, let us consider the inclusion of air bubbles into cavity 1441, which is one of the causes of missing dots. FIG. 9 is a conceptual diagram of the vicinity of the nozzle 110 when bubbles B are mixed into the cavity 141 of FIG. As shown in FIG. 9, it is assumed that the generated bubble B is generated and adhered to the wall surface of the cavity 141. (In FIG. 9, as an example of the position where the bubble B is adhered, the bubble B Shows the case where it is attached near 10).

As described above, when the bubbles B are mixed in the cavity 141, it is considered that the total weight of the ink filling the cavity 141 decreases and the inertia m decreases. Bubble B is attached to the wall of cavity 144 Thus, it is considered that the diameter of the nozzle 110 is increased by the size of the diameter, and the acoustic resistance r is reduced.

Therefore, compared to the case of Fig. 8 in which ink was ejected normally, the acoustic resistance r and the inertia m were both set small and matched with the experimental values of the residual vibration when bubbles were mixed. A result (graph) like 0 was obtained. As can be seen from the graphs of FIG. 8 and FIG. 10, when bubbles are mixed in the cavity 141, a characteristic residual vibration waveform having a higher frequency than in normal ejection is obtained. It should be noted that the attenuation of the amplitude of the residual vibration is also reduced due to a decrease in the acoustic resistance r, and it can be confirmed that the amplitude of the residual vibration is slowly reduced.

Next, we will examine the drying (fixation and thickening) of ink near the nozzle 110, which is another cause of missing dots. FIG. 11 is a conceptual diagram of the vicinity of the nozzle 110 when the ink near the nozzle 110 of FIG. 3 is fixed by drying. As shown in FIG. 11, when the ink near the nozzle 110 is dried and fixed, the ink in the captivity 141 is in a state where it is trapped in the cavity 144. Thus, when the ink near the nozzle 110 dries and thickens, it is considered that the acoustic resistance r increases.

Therefore, compared to the case of Fig. 8 where the ink was ejected normally, the acoustic resistance r was set to be large to match the experimental value of the residual vibration at the time of ink drying and sticking (thickening) near the nozzle 110. As a result, the result (graph) shown in Fig. 12 was obtained. The experimental values shown in Fig. 12 are based on the fact that the head unit 35 was left for several days without a cap (not shown) attached, and the ink near the nozzle 110 dried and thickened, and the ink was ejected. This is a measurement of the residual vibration of the diaphragm 122 in a state where the ink cannot be applied (the ink is fixed). As can be seen from the graphs of FIG. 8 and FIG. 12, when the ink near the nozzle 110 is fixed by drying, the frequency becomes extremely lower than that during normal ejection. In particular, a characteristic residual vibration waveform in which the residual vibration is overdamped is obtained. This is because the diaphragm 1 2 1 is drawn downward in FIG. 3 to eject ink droplets, and after the ink flows from the reservoir 1 4 3 into the cavity 1 4 1, the diaphragm 1 2 1 When moving upward in FIG. 3, the diaphragm 12 1 cannot vibrate rapidly (because of excessive attenuation) because there is no escape route for the ink in the cavity 14 1.

Next, the paper dust adhering to the vicinity of the nozzle 110 outlet, which is still another cause of missing dots, will be examined. Here, in the present invention, the term “paper dust” is not limited to only paper dust generated from recording paper or the like, but may be, for example, a piece of rubber such as a paper feed roller (paper feed roller) or floating in the air. This refers to anything that adheres to the vicinity of the nozzle 110, including scum, and hinders the ejection of ink droplets (droplets).

FIG. 13 is a conceptual diagram of the vicinity of the nozzle 110 when paper powder adheres to the vicinity of the nozzle 110 exit of FIG. As shown in Fig. 13, if paper dust adheres to the vicinity of the outlet of nozzle 110, ink leaks out from inside of cavity 141 through the paper dust, and nozzle 110 also leaks ink. Ink cannot be ejected. As described above, when paper dust adheres to the vicinity of the outlet of the nozzle 110 and the ink seeps out of the nozzle 110, the inside of the cavity 141 and the part of the seepage from the vibrating plate 121 appear. It is considered that the ink m increases from the normal state, and the inertia m increases. Also, it is considered that the acoustic resistance r increases due to the fibers of the paper powder attached near the outlet of the nozzle 110.

Therefore, as compared with the case of FIG. 8 in which ink is normally ejected, the inertance 111 and the acoustic resistance r are both set to be large to reduce the residual vibration when paper dust adheres near the nozzle 110 outlet. By matching with the experimental values, the result (graph) as shown in Fig. 14 was obtained. As can be seen from the graphs in Fig. 8 and Fig. 14, when paper dust adheres near the outlet of the nozzle 110, the frequency is lower than during normal ejection. The characteristic residual vibration waveform that reduces the residual vibration is obtained. (Here, the frequency of the residual vibration is higher than in the case of paper dust adhesion and ink drying. I understand.) FIG. 15 is a photograph showing the state of the nozzle 110 before and after the adhesion of the paper powder. When paper dust adheres to the vicinity of the outlet of the nozzle 110, it can be seen from FIG. 15 (b) that the ink oozes along the paper dust.

Here, both when the ink near the nozzle 110 dries and thickens, and when paper dust adheres near the outlet of the nozzle 110, the ink droplets are normally ejected. The frequency of the damped vibration is lower than that. In order to identify the cause of these two missing dots (non-ejection of ink: abnormal ejection) from the waveform of the residual vibration of the diaphragm 121, for example, it is necessary to specify the frequency, period, and phase of the damped vibration. It can be compared with a threshold value, or can be specified from the decay rate of the period change or amplitude change of the residual vibration (damped vibration).

In this way, the change (vibration pattern) of the residual vibration of the diaphragm 121 when an ink droplet is ejected from the nozzle 110 in each of the ink jet heads 100, in particular, its frequency (Vibration pattern), it is possible to detect a discharge abnormality (head abnormality) of each inkjet head 100. Also

By comparing the frequency of the residual vibration in that case with the frequency of the residual vibration during normal ejection, the cause of the ejection abnormality (head abnormality) can also be specified.

Also, when the drive circuit 18 of the head driver 33 inputs a drive signal (voltage signal) that does not eject ink droplets (droplets), the amplitude is reduced, but the residual vibration of the diaphragm is similar. A waveform is obtained. Therefore, by expanding the vertical axis of the graph showing the amplitude of the residual vibration, the calculated values and experimental results similar to the graphs in Figs. 10, 12, and 14 corresponding to the causes of each discharge abnormality Value is obtained. Therefore, the electrostatic actuator 120 is driven to the extent that ink droplets are not ejected, and the residual vibration of the diaphragm 121 at that time is detected. This makes it possible to detect an abnormal discharge of the ink jet 100. Hereinafter, an abnormality of the inkjet head 100 that can be detected without ejecting a droplet will be referred to simply as “ejection abnormality”. Next, the discharge abnormality detecting means 10 will be described. FIG. 16 is a schematic block diagram of the discharge abnormality detecting means 10 shown in FIG. As shown in FIG. 16, the discharge abnormality detection means 10 includes: an oscillation circuit 11; an F / V conversion circuit 12; a waveform shaping circuit 15; and a residual vibration detection means 16; Measuring means 17 for measuring the period, amplitude, etc., from the residual vibration waveform data detected by the residual vibration detecting means 16, and the inkjet head 100 based on the period, etc., measured by the measuring means 17. Determination means 20 for determining a discharge abnormality (head abnormality). In the discharge abnormality detecting means 10, the residual vibration detecting means 16 oscillates the oscillation circuit 11 based on the residual vibration of the diaphragm 121 of the electrostatic actuator 120, and calculates the oscillation frequency from the oscillation frequency. The F / V conversion circuit 12 and the waveform shaping circuit 15 form and detect a vibration waveform. Then, the measuring means 17 measures the cycle of the residual vibration based on the detected vibration waveform, and the determining means 20 determines each head in the printing means 3 based on the measured cycle of the residual vibration. The discharge abnormality of each of the inkjet heads 100 included in the unit 35 is detected and determined. Hereinafter, each component of the discharge abnormality detecting means 10 will be described.

First, a method of using the oscillation circuit 11 to detect the frequency (frequency) of the residual vibration of the diaphragm 121 of the electrostatic actuator 120 will be described. FIG. 17 is a conceptual diagram in the case where the electrostatic actuator 120 of FIG. 3 is a parallel plate capacitor. FIG. 18 is a conceptual diagram of the capacitor constituted of the electrostatic actuator 120 of FIG. FIG. 3 is a circuit diagram of an oscillation circuit 11 including a capacitor. The oscillation circuit 11 shown in FIG. 18 is a CR oscillation circuit that uses the hysteresis characteristic of the Schmitt trigger, but the present invention is not limited to such a CR oscillation circuit, Any oscillation circuit that uses the capacitance component (capacitor C) Such an oscillation circuit may be used. The oscillation circuit 11 may have a configuration using, for example, an LC oscillation circuit. Further, in the present embodiment, an example using Schmitt trigger inversion is described. However, for example, a CR oscillation circuit using three stages of inversion may be configured.

In the ink jet head 100 shown in FIG. 3, as described above, the diaphragm 122 and the segment electrode 122 with a very small space (gap) form an opposing electrode. It is composed of one hundred and twenty one days. This electrostatic actuator 120 can be considered as a parallel plate capacitor as shown in FIG. The capacitance of this capacitor is C, the surface area of each of the diaphragm 1 2 1 and the segment electrode 1 2 is S, the distance (gap length) between the two electrodes 1 2 1 and 1 2 is g, and both electrodes are sandwiched. If the permittivity of the space (void) is ε (where the permittivity of vacuum is ε 0 and the relative permittivity of the void is ε r, ε = ε 0 · ε r), the capacitor (static The capacitance C (x) of the electrical equipment 120) is expressed by the following equation.

[Equation 2]

C (x) = s ₀ -s _r (F) (4)

g "X

Note that X in Expression (4) indicates the amount of displacement of the diaphragm 121 from the reference position caused by residual vibration of the diaphragm 121, as shown in FIG.

As can be seen from equation (4), when the gap length g (gap length g—displacement X) decreases, the capacitance C (x) increases, and conversely, the gap length g (gap length g—displacement) As the quantity X) increases, the capacitance C (x) decreases. Thus, the capacitance C (X) is inversely proportional to (gap length g—displacement X) (gap length g if X is 0). The electrostatic actuator shown in Fig. 3 In the eta 120, since the air gap is filled with air, the relative permittivity can be determined as £ _r = 1.

In general, as the resolution of the droplet discharge device (in the present embodiment, the ink jet printer 1) increases, the size of the discharged ink droplet (ink dot) becomes smaller. Will be denser and smaller. As a result, the surface area S of the vibration plate 121 of the inkjet head 100 becomes small, and a small electrostatic actuator 120 is formed. Furthermore, the gap length g of the electrostatic actuator 120, which changes due to the residual vibration caused by the ink droplet ejection, is the initial gap g. Therefore, as can be seen from Equation (4), the change in capacitance of the electrostatic factor 120 is very small.

In order to detect the amount of change in the capacitance of the electrostatic actuator 120 (depending on the vibration pattern of the residual vibration), the following method is used. An oscillation circuit as shown in Fig. 18 is configured based on the capacitance, and a method of analyzing the frequency (period) of the residual vibration based on the oscillated signal is used. The oscillator circuit 11 shown in Fig. 18 is composed of a capacitor (C) composed of an electrostatic actuator 120, a Schmitt trigger inverter 111, and a resistor element (R) 112. Consists of

When the output signal of the Schmitt trigger inverter is at a high level, the capacitor C is charged via the resistive element 112. When the charging voltage of capacitor C (the potential difference between diaphragm 122 and segment electrode 122) reaches the input threshold voltage V _T of the sig- nal trigger bar 111, the shutter trigger trigger bar 1 11 The output signal of 1 is inverted to Low level. Then, when the output signal of the Schmitt trigger inverter 111 becomes the Low level, the charge that has been charged in the capacitor C via the resistance element 112 is discharged. This discharge causes the voltage of the capacitor C to rise When the input threshold voltage V _T — is reached, the output signal of the Schmitt trigger inverts again to the High level. Thereafter, this oscillation operation is repeated.

Here, in order to detect the time change of the capacitance of the capacitor C in each of the above phenomena (bubble mixing, drying, adhesion of paper powder, and normal ejection), the oscillation frequency of the oscillation circuit 11 is The oscillation frequency must be set so that the frequency of the highest residual vibration can be detected when bubbles are mixed (see Fig. 10). Therefore, the oscillation frequency of the oscillation circuit 11 must be, for example, several times to several tens times or more the frequency of the residual vibration to be detected, that is, a frequency that is at least one digit higher than the frequency when bubbles are mixed. . In this case, it is preferable to set the oscillation frequency at which the residual vibration frequency at the time of air bubble mixing can be detected, since the frequency of the residual vibration at the time of air bubble mixing is higher than that at the time of normal ejection. Otherwise, the frequency of the residual vibration cannot be detected accurately for the phenomenon of abnormal discharge. Therefore, in the present embodiment, the time constant of CR of the oscillation circuit 11 is set according to the oscillation frequency. By setting the oscillation frequency of the oscillation circuit 11 high as described above, a more accurate residual vibration waveform can be detected based on the minute change in the oscillation frequency.

Incidentally, in each period of the oscillation frequency of the oscillation signal outputted from the oscillation circuit 1 1 (pulse), and counts the pulse by using a measuring count pulse (counter), the electrostatic capacitor C in the initial gap g _Q By subtracting the count value of the pulse of the oscillation frequency when oscillating with the capacitance from the measured count value, digital information of the residual vibration waveform for each oscillation frequency can be obtained. By performing digital-to-analog (D / A) conversion based on these digital information, a rough residual vibration waveform can be generated. Such a method may be used, but a high-frequency (high-resolution) pulse that can measure small changes in the oscillation frequency is required for the measurement count pulse (counter pulse). In order to increase the cost of such a count pulse (counter), the discharge abnormality detecting means 10 uses the FZV conversion circuit 12 shown in FIG. FIG. 19 is a circuit diagram of the F / V conversion circuit 12 of the discharge abnormality detection means 10 shown in FIG. As shown in FIG. 19, the F / V conversion circuit 12 includes three switches SW1, SW2, and SW3, two capacitors C1 and C2, a resistance element R1, and a constant current Is. It is composed of a constant current source 13 to output and a buffer 14. The operation of the FZV conversion circuit 12 will be described with reference to the timing chart of FIG. 20 and the graph of FIG.

First, a method for generating the charge signal, the hold signal, and the clear signal shown in the timing chart of FIG. 20 will be described. The charging signal is generated such that a fixed time tr is set from the rising edge of the oscillation pulse of the oscillation circuit 11, and the charge signal is at the High level during the fixed time tr. The hold signal rises in synchronization with the rising edge of the charging signal, is held at the High level for a predetermined fixed time, and falls to the Low level. The clear signal rises in synchronization with the falling edge of the hold signal, is held at the High level for a predetermined fixed time, and is generated so as to fall to the Low level. As will be described later, the transfer of the charge from the capacitor C1 to the capacitor C2 and the discharge of the capacitor C1 are performed instantaneously, so that the pulses of the hold signal and the clear signal correspond to the output signal of the oscillator circuit 11. It is sufficient that one pulse is included before the next rising edge, and the pulse is not limited to the rising edge and the falling edge as described above.

To obtain a clean residual vibration waveform (voltage waveform), refer to Fig. 21 for the fixed time tr and! : Explain the setting method of 1. Fixed time tr is adjusted from the cycle of the oscillation pulse electrostatic Akuchi Yue Isseki 1 20 oscillates by an electrostatic capacitance C at the time of the initial gap length g _Q, charging range of the charging potential by the charging time t 1 is C 1 It is set to be about 1/2 of. Also, the gap length g is The gradient of the charging potential is set so that the charging range of the capacitor C1 is not exceeded between the charging time t2 at the large (Max) position and the charging time t3 at the minimum (Min) position. You. That is, since the slope of the charging potential is determined by dV / dt = Is / C1, the output constant current Is of the constant current source 13 may be set to an appropriate value. By setting the output constant current Is of the constant current source 13 as high as possible within the range, a small change in the capacitance of the capacitor constituted by the electrostatic actuator 120 can be detected with high sensitivity. Thus, a minute change of the diaphragm 121 of the electrostatic actuator 120 can be detected.

Next, the configuration of the waveform shaping circuit 15 shown in FIG. 16 will be described with reference to FIG. FIG. 22 is a circuit diagram showing a circuit configuration of the waveform shaping circuit 15 of FIG. The waveform shaping circuit 15 outputs the residual vibration waveform to the determination means 20 as a rectangular wave. As shown in FIG. 22, the waveform shaping circuit 15 includes two capacitors C 3 (DC component removing means) and C 4, two resistance elements R 2 and 3, and two DC voltage sources V ref 1 and V ref 1. It is composed of V ref 2, an amplifier (op-amp) 15 1, and a comparator (comparison) 152. In the waveform shaping process of the residual vibration waveform, the detected peak value may be output as it is to measure the amplitude of the residual vibration waveform.

The output of the buffer 14 of the F / V conversion circuit 12 has the initial gap g of the electrostatic actuator 120. The DC component (DC component) based on the capacitance is included. Since the DC component varies depending on each ink jet head 100, the capacitor C3 removes the DC component of the capacitance. Then, the capacitor C3 removes the DC component in the output signal of the buffer 14, and outputs only the AC component of the residual vibration to the inverting input terminal of the operational amplifier 151.

1 5 1 is the buffer of the FZV conversion circuit 12 from which the DC component has been removed. A low-pass filter for inverting and amplifying the output signal of the filter 14 and removing a high frequency band of the output signal is configured. It is assumed that the operational amplifier 15 1 is a single power supply circuit. The operational amplifier 15 1 constitutes an inverting amplifier composed of two resistance elements R 2 and R 3, and the input residual vibration (AC component) is amplified by one R 3 / R twice.

In addition, because of the single power supply operation of the operational amplifier 151, the amplified diaphragm 121 oscillating around the potential set by the DC voltage source Vref1 connected to its non-inverting input terminal A residual vibration waveform is output. Here, the DC voltage source V r e ί 1 is set to about a half of the voltage range in which the operational amplifier 15 1 can operate with a single power supply. Further, the operational amplifier 15 1 forms a single-pass filter having a cutoff frequency of 1 / (27TXC 4 XR 3) by the two capacitors C 3 and C 4. Then, as shown in the timing chart of FIG. 20, the residual vibration waveform of the diaphragm 121 amplified after the removal of the DC component is output by another DC comparator 152 in the next stage. It is compared with the potential of the voltage source Vref2, and the comparison result is output from the waveform shaping circuit 15 as a rectangular wave. It should be noted that the DC voltage source Vref1 may share another DC voltage source Vref1.

Next, the operation of the F / V conversion circuit 12 and the waveform shaping circuit 15 in FIG. 19 will be described with reference to the timing chart shown in FIG. The FZV conversion circuit 12 shown in FIG. 19 operates based on the charge signal, the clear signal, and the hold signal generated as described above. In the timing chart of FIG. 20, when the drive signal of the electrostatic actuator 120 is input to the ink jet head 100 via the head driver 33, as shown in FIG. 6 (b). The diaphragm 122 of the electrostatic actuator 120 is attracted to the segment electrode 122 side, and contracts rapidly upward in FIG. 6 in synchronization with the falling edge of this drive signal ( (See Fig. 6 (c)). In synchronization with the falling edge of the drive signal, the drive detection switch signal for switching between the drive circuit 18 and the ejection failure detection means 10 becomes the Hig level. This drive / detection switching signal is held at the High level during the drive suspension period of the corresponding inkjet head 100, and goes to the Low level before the next drive signal is input. While this drive Z detection switching signal is at the High level, the oscillation circuit 11 in Fig. 18 oscillates while changing the oscillation frequency in response to the residual vibration of the diaphragm 1 21 of the electrostatic actuator 120. are doing.

As described above, from the falling edge of the drive signal, that is, the rising edge of the output signal of the oscillation circuit 11, a fixed time set in advance so that the waveform of the residual oscillation does not exceed the range where the capacitor C1 can be charged. Until tr elapses, the charging signal is held at the High level. Note that while the charging signal is at the High level, the switch SW1 is off.

• When the fixed time tr elapses and the charging signal goes low, the switch SW1 is turned on in synchronization with the falling edge of the charging signal (see Fig. 19). The capacitor C1 is connected, and the capacitor C1 is charged with the slope I s ZC1 as described above. The capacitor C1 is charged while the charge signal is at the Low level, that is, until the charge signal becomes the High level in synchronization with the rising edge of the next pulse of the output signal of the oscillation circuit 11.

When the charge signal goes to the high level, switch SW1 is turned off (open), and constant current source 13 and capacitor C1 are disconnected. At this time, the potential (that is, ideally I s X t 1 / C 1 (V)) charged during the period t 1 in which the charge signal is at the L◦w level is stored in the capacitor C 1. ing. In this state, when the hold signal goes to the high level, the switch SW2 is turned on (see FIG. 19), and the capacitors C1 and C2 are connected via the resistance element R1. After connecting switch SW2, charge two capacitors C1 and C2. The charge and discharge are performed by the electric potential difference, and the electric charge moves from the capacitor C1 to the capacitor C2 such that the electric potential difference between the two capacitors C1 and C2 becomes substantially equal.

Where the capacitor. The capacitance of the capacitor C2 is set to about 1Z10 or less with respect to the capacitance of 1. Therefore, the amount of charge (used) that moves due to charging and discharging caused by the potential difference between the two capacitors C 1 and C 2 is less than 1/10 of the charge charged in the capacitor C 1. Therefore, even after the electric charge is transferred from the capacitor C1 to the capacitor C2, the potential difference of the capacitor C1 does not change much (it does not decrease so much). In the FZV conversion circuit 12 of FIG. 19, in order to prevent the charging potential from jumping rapidly due to the inductance of the wiring of the FZV conversion circuit 12 when the capacitor C2 is charged. The first-order low-pass filter is composed of the resistor R1 and the capacitor C2.

After the charge potential of the capacitor C2 is substantially equal to the charge potential of the capacitor C1, the hold signal goes low, and the capacitor C1 is disconnected from the capacitor C2. Further, when the clear signal becomes the High level and the switch SW3 is turned on, the capacitor C1 is connected to the ground GND, and the discharging operation is performed so that the charge stored in the capacitor C1 becomes 0. . After the discharge of the capacitor C1, the clear signal goes to the Low level, and the switch SW3 turns off, thereby disconnecting the upper electrode of the capacitor C1 in Fig. 19 from the ground GND until the next charge signal is input. That is, it waits until the charging signal becomes Low level.

The potential held in the capacitor C2 is updated every time the rising edge of the charge signal rises, that is, each time the charging of the capacitor C2 is completed, and the residual vibration of the diaphragm 121 via the buffer 14 This is output as a waveform to the waveform shaping circuit 15 in FIG. Therefore, the oscillation frequency of the oscillation circuit 11 becomes higher. By setting the capacitance of the electrostatic actuator 120 (in this case, the fluctuation width of the capacitance due to the residual vibration) and the resistance value of the resistive element 112, as shown in the figure, Since each step (step) of the potential of capacitor C 2 (output of buffer 14) shown in the timing chart of 20 becomes more detailed, the temporal change in capacitance due to residual vibration of diaphragm 121 Can be detected in more detail.

Similarly, the charging signal repeats from Low level to High level to Low level. The potential held in the capacitor C2 at the above-mentioned predetermined timing passes through the buffer 14 and the waveform shaping circuit 15 Is output to In the waveform shaping circuit 15, the DC component of the voltage signal (potential of the capacitor C 2 in the timing chart of FIG. 20) input from the buffer 14 is removed by the capacitor C 3, and the resistance element R Input to the inverting input terminal of the operational amplifier 15 1 via 2. The input AC (A C) component of the residual vibration is inverted and amplified by the operational amplifier 151, and is output to one input terminal of the comparator 152. The comparator 15 2 compares the potential (reference voltage) preset by the DC voltage source V ref 2 with the potential of the residual vibration waveform (AC component), and outputs a square wave (see FIG. 20). Next, the switching timing between the ink droplet ejection operation (drive) of the inkjet head 100 and the ejection abnormality detection operation (drive suspension) will be described. FIG. 23 is a block diagram schematically showing the switching means 23 for switching between the drive circuit 18 and the discharge abnormality detection means 10. In FIG. 23, the drive circuit 18 in the head dryer 33 shown in FIG. 16 will be described as a drive circuit for the ink jet head 100. As also shown in the timing chart of FIG. 20, the ejection failure detection processing is executed between the drive signals of the ink jet head 100, that is, during the drive suspension period.

In FIG. 23, switching means for driving the electrostatic actuator 120 23 is initially connected to the drive circuit 18 side. As described above, when a drive signal (voltage signal) is input to the diaphragm 12 1 from the drive circuit 18, the electrostatic actuating unit 120 is driven, and the diaphragm 12 1 When the applied voltage becomes 0, it is suddenly displaced away from the segment electrode 122 and starts to vibrate (residual vibration). At this time, ink droplets are ejected from the nozzle 110 of the inkjet head 100.

When the drive signal pulse falls, a drive / detection switching signal (see the timing chart in FIG. 20) is input to the switching means 23 in synchronization with the falling edge, and the switching means 23 is driven by the drive circuit 18 Is switched to the discharge abnormality detection means (detection circuit) 10 side, and the electrostatic work 120 (used as a capacitor of the oscillation circuit 11) is connected to the discharge abnormality detection means 10.

Then, the discharge abnormality detection means 10 executes the above-described discharge abnormality (missing dot) detection processing, and outputs the residual vibration of the diaphragm 12 1 output from the comparator 15 2 of the waveform shaping circuit 15. The waveform data (rectangular wave data) is digitized by the measuring means 17 into the period and amplitude of the residual vibration waveform. In the present embodiment, the measuring means 17 measures a specific vibration cycle from the residual vibration waveform data, and outputs the measurement result (numerical value) to the judging means 20.

Specifically, the measuring means 17 measures the time (period of the residual vibration) from the first rising edge of the waveform (rectangular wave) of the output signal of the comparator 152 to the next rising edge. The pulses of the reference signal (predetermined frequency) are counted using a counter (not shown), and the period of the residual vibration (specific vibration period) is measured from the count value. The measuring means 17 measures the time from the first rising edge to the next falling edge, and outputs the measured time, 2 {'i rising time, to the determining means 20 as the period of the residual vibration. May be. Hereinafter, the period of the residual vibration obtained in this manner is referred to as Tw.

Judging means 20 is used to determine the particular of the residual vibration waveform measured by measuring means 17. Based on the vibration cycle (measurement result), the presence / absence of a nozzle discharge abnormality (head abnormality), the cause of the discharge abnormality (head abnormality), the amount of comparison deviation, and the like are determined, and the determination result is output to the control unit 6. The control unit 6 stores this determination result in a predetermined storage area of an EEPROM (storage means) 62. Then, at the timing when the next drive signal from the drive circuit 18 is input, the drive / detection switching signal is input again to the switching means 23, and the drive circuit 18 and the electrostatic actuator 120 are connected to each other. Connecting. The drive circuit 18 maintains the ground (GND) level once the drive voltage is applied, so that the above-described switching is performed by the switching means 23 (see the timing chart of FIG. 20). As a result, the residual vibration waveform of the diaphragm 121 of the electrostatic actuator 120 can be accurately detected without being affected by disturbance from the drive circuit 18 or the like.

Note that, in the present invention, the residual vibration waveform data is not limited to the rectangular waveform generated by the comparator 152. For example, the residual vibration amplitude data output from the operational amplifier 15 1 is digitized as needed by the measuring means 17 for A / D conversion without performing the comparison processing by the comparator 15 2, and is digitized as needed. Based on the data obtained, the determination means 20 may determine whether or not there is a discharge abnormality, and the determination result may be stored in the storage means 62.

In addition, the meniscus of the nozzle 110 (the surface where the ink inside the nozzle 110 contacts the atmosphere) vibrates in synchronization with the residual vibration of the diaphragm 121, so that the inkjet head 100 ejects ink droplets. After the operation, after waiting for the residual vibration of the meniscus to attenuate in a time substantially determined by the acoustic resistance r (waiting for a predetermined time), the next ejection operation is performed. In the present invention, since the residual vibration of the diaphragm 121 is detected by effectively utilizing the standby time, it is possible to detect a discharge abnormality that does not affect the driving of the ink jet head 100. That is, the processing for detecting the abnormal discharge of the nozzle 110 of the inkjet head 100 can be performed without lowering the throughput of the inkjet printer 1 (droplet discharging device). Can be performed.

As described above, when air bubbles are mixed into the cavity 140 of the ink jet head 100, the frequency becomes higher than the residual vibration waveform of the diaphragm 122 during normal ejection. On the contrary, the cycle is shorter than the cycle of the residual vibration during normal ejection. Also, if the ink near the nozzle 110 thickens and sticks due to drying, the residual vibration will be over-attenuated and the frequency will be considerably lower than the residual vibration waveform during normal ejection. Is much longer than the period of the residual vibration during normal ejection. When paper dust adheres to the vicinity of the outlet of the nozzle 110, the frequency of the residual vibration is lower than the frequency of the residual vibration during normal ejection, but is lower than the frequency of the residual vibration during drying of the ink. Therefore, the cycle is longer than the cycle of the residual vibration during normal ejection and shorter than the cycle of the residual vibration during ink drying.

Therefore, a predetermined range T r is provided as the period of the residual vibration during normal ejection, and the period of the residual vibration when paper dust adheres to the exit of the nozzle 110 and the ink near the exit of the nozzle 110 By setting a predetermined threshold value (predetermined threshold value) T1 to distinguish the cycle of the residual vibration when the ink is dried, the cause of such an ink jet head 100 discharge abnormality is determined. can do. The determining means 20 determines whether the cycle T w of the residual vibration waveform detected by the above-described discharge abnormality detection processing is a cycle in a predetermined range, and whether the cycle is longer than a predetermined threshold value. Thus, the cause of the discharge abnormality (head abnormality) is determined.

Next, the operation of the droplet discharge device of the present invention will be described based on the configuration of the inkjet printer 1 described above. First, the ejection abnormality detection processing (including the drive noise detection switching processing) for one nozzle 110 of one inkjet head 100 will be described. FIG. 24 is a flowchart showing a discharge abnormality detection / determination process. Print data to be printed (Ejection data in flushing operation may be used. ) Is input from the host computer 8 to the control unit 6 via the interface (IF) 9, the discharge abnormality detection processing is executed at a predetermined timing. For convenience of explanation, the flowchart shown in FIG. 24 shows a discharge abnormality detection process corresponding to the discharge operation of one inkjet head 100, that is, one nozzle 110.

First, a drive signal corresponding to print data (ejection data) is input from the drive circuit 18 of the head driver 33, and thereby, based on the timing of the drive signal as shown in the timing chart of FIG. A drive signal (voltage signal) is applied between both electrodes of the device 120 (step S101). Then, based on the drive Z detection switching signal, the control unit 6 determines whether or not the ejected inkjet head 100 is in the drive suspension period (step S102). Here, the drive / detection switching signal becomes High level in synchronization with the falling edge of the drive signal (see FIG. 20), and is input from the control unit 6 to the switching unit 23.

When the drive / detection switching signal is input to the switching means 23, the switching means 23 disconnects the electrostatic actuator 120, that is, the capacitor forming the oscillation circuit 11 from the driving circuit 18. Then, it is connected to the discharge abnormality detection means 10 (detection circuit) side, that is, to the oscillation circuit 11 of the residual vibration detection means 16 (step S103). Then, a residual vibration detection process described later is executed (step S104), and the measuring means 17 measures a predetermined numerical value from the residual vibration waveform data detected in the residual vibration detection process (step S104). 1 0 5). Here, as described above, the measuring means 17 measures the period of the residual vibration from the residual vibration waveform data.

Next, the determination means 20 executes a discharge abnormality determination process, which will be described later, based on the measurement result of the measurement means (step S 106), and stores the determination result in an EE PROM (storage means) 6 2 In a predetermined storage area. And In step S108, it is determined whether or not the ink jet head 100 is in the drive period. That is, after the drive suspension period ends, it is determined whether or not the next drive signal has been input, and the process stands by at step S108 until the next drive signal is input.

When the drive Z detection switch signal goes low in synchronization with the rising edge of the drive signal at the timing when the pulse of the next drive signal is input (“yes” in step S108), the switching means 23 The connection with the electrostatic actuator 120 is switched from the discharge abnormality detection means (detection circuit) 10 to the drive circuit 18 (step S109), and the discharge abnormality detection processing ends.

Note that the flowchart shown in FIG. 24 shows a case where the measuring means 17 measures the period from the residual vibration waveform detected by the residual vibration detection processing (residual vibration detecting means 16). The present invention is not limited to such a case. For example, the measuring unit 17 may measure the phase difference and amplitude of the residual vibration waveform from the residual vibration waveform data detected in the residual vibration detection processing.

Next, the residual vibration detection processing (subroutine) in step S104 of the flowchart shown in FIG. 24 will be described. FIG. 25 is a flowchart showing the residual vibration detection processing. As described above, when the electrostatic actuator 120 and the oscillation circuit 11 are connected by the switching means 23 (step S103 in FIG. 24), the oscillation circuit 11 constitutes a CR oscillation circuit, Oscillation is performed based on the change in capacitance of the electrostatic actuator 120 (residual vibration of the diaphragm 121 of the electrostatic actuator 120) (step S201).

As shown in the above timing chart and the like, a charge signal, a hold signal, and a clear signal are generated in the F / V conversion circuit 12 based on the output signal (pulse signal) of the oscillation circuit 11, and these signals are generated. The F / V conversion circuit 12 converts the frequency of the output signal of the oscillation circuit 11 into a voltage based on the F / V conversion circuit 12 (step S202), and the FZV conversion circuit 12 outputs the diaphragm 1 2 1 residual vibration waveform data is output. From the residual vibration waveform data output from the F / V conversion circuit 12, the DC component (DC component) is removed by the capacitor C 3 of the waveform shaping circuit 15 (step S 203), and the operational amplifier 15 1 As a result, the residual vibration waveform (AC component) from which the DC component has been removed is amplified (step S204).

The residual vibration waveform data after the amplification is shaped into a pulse by a predetermined process and is converted into a pulse (step S205). That is, in the present embodiment, the comparator 152 compares the voltage value (predetermined voltage value) set by the DC voltage source Vref2 with the output voltage of the operational amplifier 151. The comparator 152 outputs a binarized waveform (rectangular wave) based on the comparison result. The output signal of the comparator 152 is an output signal of the residual vibration detecting means 16 and is output to the measuring means 17 for performing the discharge abnormality determination processing, and the residual vibration detecting processing ends.

Next, the discharge abnormality determination process (subroutine) in step S106 of the flowchart shown in FIG. 24 will be described. FIG. 26 is a flowchart showing a discharge abnormality determination process performed by the control unit 6 and the determination unit 20. The determination means 200 determines whether or not the ink droplet has been normally ejected from the corresponding inkjet head 100 based on the measurement data (measurement result) such as the cycle measured by the measurement means 17 described above. If the ejection is not performed, that is, if the ejection is abnormal, the cause is determined.

First, the control unit 6 outputs the predetermined range Tr of the cycle of the residual vibration and the predetermined threshold T1 of the cycle of the residual vibration stored in the EEPROM 62 to the determination means 20. The predetermined range T r of the cycle of the residual vibration is such that the residual vibration cycle at the time of normal ejection has an allowable range that can be determined as normal. These data are stored in a memory (not shown) of the determination means 20, and the following processing is executed. The measurement result measured by the measuring means 17 in step S105 of FIG. 24 is input to the judging means 20 (step S301). Here, in the present embodiment, the measurement result is the period Tw of the residual vibration of the diaphragm 122.

In step S302, the determination means 20 determines whether or not the residual vibration cycle Tw exists, that is, whether or not the discharge abnormality detection means 10 has not obtained residual vibration waveform data. When it is determined that the period Tw of the residual vibration does not exist, the determination unit 20 determines that the nozzle 110 of the inkjet head 100 has not ejected an ink droplet in the ejection abnormality detection process. It is determined that the nozzle is a discharge nozzle (step S306). When it is determined that the residual vibration waveform data is present, subsequently, in step S303, the determination means 20 sets the predetermined range Tr in which the cycle Tw is recognized as the cycle during normal ejection. It is determined whether it is within.

When it is determined that the period Tw of the residual vibration is within the predetermined range Tr, it means that the ink droplet has been normally ejected from the corresponding ink jet head 100, and the determination means 2 If 0, it is determined that the nozzle 110 of the inkjet head 100 has normally ejected an ink droplet (normal ejection) (step S307). When it is determined that the period Tw of the residual vibration is not within the predetermined range Tr, subsequently, in step S304, the determining means 20 determines that the period Tw of the residual vibration is within the predetermined range Tr. It is determined whether it is shorter than Tr.

If it is determined that the cycle of the residual vibration Tw is shorter than the predetermined range Tr, it means that the frequency of the residual vibration is high, and as described above, the cavities 14 of the inkjet head 100 are determined. It is considered that air bubbles are mixed in 1 and the determination means 20 determines that air bubbles are mixed in the cavity 14 1 of the inkjet head 100 (bubble mixing) ( Step S308).

If it is determined that the period Tw of the residual vibration is longer than the predetermined range Tr, subsequently, the determining means 20 sets the period Tw of the residual vibration to a predetermined threshold T1. It is determined whether it is longer than (step S305). When it is determined that the cycle Tw of the residual vibration is longer than the predetermined threshold T1, it is considered that the residual vibration is excessively damped, and the determination means 20 determines the nozzle 11 of the inkjet head 100. It is determined that the ink near 0 is thickened by drying (dry) (step S309).

If it is determined in step S305 that the cycle Tw of the residual vibration is shorter than the predetermined threshold value T1, the cycle Tw of the residual vibration satisfies Tr <Tw <T1. As described above, it is considered that paper dust adheres to the vicinity of the outlet of the nozzle 110 whose frequency is higher than that of drying, and the determination means 20 determines the nozzle 110 of the inkjet head 100 as described above. It is determined that paper dust is attached near the outlet (paper dust attached) (step S3110).

As described above, when the determination unit 20 determines the normal ejection or the cause of the ejection abnormality of the target inkjet head 100 (steps S306 to S310), the determination result is output to the control unit 6 And the discharge abnormality determination processing ends.

The determination result corresponding to each of the inkjet heads 100 is associated with the target inkjet head 100 to be processed in step S107 of FIG. 24, which will be described later, and stored in the EEPROM (storage means) of the control unit 6. ) It is stored in the 62 predetermined storage area.

Next, assuming a plurality of inkjet heads (droplet ejection heads) 100, that is, an inkjet printer 1 having a plurality of nozzles i10, the ejection selection means (nozzle selector) 182 of the ink jet printer 1 A description will be given of the timing of the discharge abnormality detection and determination of each of the inkjet heads 100.

In the following, in order to make the description easy to understand, one head unit 35 of the plurality of head units 35 provided in the printing unit 3 will be described. In addition, the head unit 35 includes five inkjet heads 100a to 100e (that is, five nozzles 110). In the present invention, the printing unit 3 includes The number of the head units 35 and the number of the ink jet heads 100 (nozzles 110) provided in each head unit 35 may be any number. FIG. 27 to FIG. 30 are block diagrams showing some examples of ejection abnormality detection / judgment timing in the ink jet printer 1 including the ejection selection means 18. Hereinafter, configuration examples of the respective drawings will be sequentially described.

FIG. 27 shows an example of the timing of detecting a discharge abnormality of a plurality (five) of the inkjet heads 100a to 100e (when there is one discharge abnormality detection means 10). As shown in FIG. 27, an ink jet printer 1 having a plurality of ink jet heads 100a to 100e is provided with a drive waveform generating means 181, which generates a drive waveform, and any of the nozzles. A discharge selecting means 182 which can select whether to discharge an ink droplet from 110, and a plurality of driving means selected by the discharging selecting means 18 2 and driven by the driving waveform generating means 18 1 An inkjet head 100a to 100e. In the configuration of FIG. 27, the configuration other than the above is the same as that shown in FIG. 2, FIG. 16, and FIG.

In the present embodiment, the drive waveform generation means 18 1 and the ejection selection means 18 2 are described as being included in the drive circuit 18 of the head driver 33 (in FIG. 27, the switching means 23 In general, both are configured in the head driver 33). However, the present invention is not limited to this configuration. For example, the driving waveform generating unit 18 1 May be configured independently of the head driver 3 3.

As shown in FIG. 27, the ejection selection means 18 2 includes a shift register 18 2 a, a latch circuit 18 2 b, and a driver 18 2 c. Shift The print data (ejection data) output from the host computer 8 shown in FIG. 2 and subjected to predetermined processing by the control unit 6 and a clock signal (CLK) are sequentially input to the register 182a. This print data is sequentially shifted from the first stage of the shift register 18a to the subsequent stage in accordance with the input pulse of the clock signal (CLK) (each time the clock signal is input), and is input. The data is output to the latch circuit 18b as print data corresponding to a to l00e. In the ejection abnormality detection process described later, ejection data at the time of flashing (preliminary ejection) is input instead of print data. This ejection data is defined as all the ink jet heads 100a to 100c. Means the print data for e.

The latch circuit 18 2 b stores the print data corresponding to the number of the nozzles 110 of the head unit 35, that is, the number of the ink jet heads 100, in the shift register 182 a. Each output signal of the shift register 18a is latched by the input latch signal. Here, when the CLEAR signal is input, the latched state is released, the output signal of the latched shift register 18a becomes 0 (latch output is stopped), and the printing operation is stopped. When the CLEAR signal is not input, the latched print data of the shift register 18a is output to the dryino 18c. After the print data output from the shift register 18 2 a is latched by the latch circuit 18 2 b, the next print data is input to the shift register 18 2 a, and the latch circuit 18 2 is synchronized with the print timing. The latch signal of b is sequentially updated.

The driver 18 2 c connects the drive waveform generating means 18 1 to the electrostatic actuator 120 of each inkjet head 100, and the latch output from the latch circuit 18 2 b A drive waveform is generated for each electrostatic actuator 120 (specified) by signal (any one of inkjet heads 100a to 100e or all electrostatic actuators 120). Means 1 8 1 Output signal ( Drive signal), and the drive signal (voltage signal) is applied between both electrodes of the electrostatic actuator 120.

The ink jet printer 1 shown in FIG. 27 includes one driving waveform generating means 18 1 for driving a plurality of ink jet heads 100 a to 100 e, and each ink jet head 100 a Ejection abnormality detecting means 10 for detecting an ejection abnormality (ink droplet non-ejection) with respect to any one of the ink jet heads 100 to 100 e, and an ejection abnormality detected by the ejection abnormality detecting means 10. A storage means 62 for storing (storing) a determination result of a cause and the like, and one switching means 23 for switching between the drive waveform generation means 18 1 and the ejection abnormality detection means 10 are provided. Therefore, the ink jet printer 1 has one of the ink jet heads 100 a to 100 e selected by the dry nozzle 182 c based on the drive signal input from the drive waveform generating means 18 1. One or more are driven, and a drive Z detection switching signal is input to the switching means 23 after the ejection driving operation, whereby the switching means 23 is switched from the drive waveform generation means 18 1 to the ejection abnormality detection means 10 by the ink jet head 100. After switching the connection with the electrostatic actuator 120, the discharge abnormality detecting means 10 detects the nozzle 110 of the ink jet 100 based on the residual vibration waveform of the diaphragm 121. This is to detect an ejection failure (ink droplet non-ejection) and determine the cause of the ejection failure. When the ejection abnormality is detected and determined for the nozzle 110, the nozzle 110 of the next designated ink jet head 100 is then determined based on the drive signal input from the drive waveform generation means 18 1. The discharge abnormality is detected and determined in the same manner, and similarly, the discharge abnormality of the nozzle 110 of the inkjet head 100 driven by the output signal of the drive waveform generating means 18 is sequentially detected and determined. Then, as described above, the residual vibration detecting means 16 is used to detect the residual vibration of the diaphragm 12 1. When the dynamic waveform is detected, the measuring means 17 measures the period of the residual vibration waveform based on the waveform data, and the judging means 20 determines whether the ejection is normal or abnormal based on the measurement result of the measuring means 17. In the case of a discharge abnormality (head abnormality), the cause of the discharge abnormality is determined, and the determination result is output to the storage means 62.

As described above, in the ink jet printer 1 shown in FIG. 27, the ejection abnormality is sequentially detected and determined in the ink droplet ejection driving operation for each nozzle 110 of the plurality of inkjet heads 100a to 100e. It is only necessary to provide one discharge abnormality detection means 10 and one switching means 23, and the circuit configuration of the ink jet printer 1 capable of detecting and determining the discharge abnormality can be scaled down. At the same time, an increase in the manufacturing cost can be prevented.

FIG. 28 shows an example of the timing of the ejection abnormality detection of a plurality of ink jet heads 100 (when the number of ejection abnormality detection means 10 is the same as the number of ink jet heads 100). The ink jet printer 1 shown in FIG. 28 has one discharge selection means 18 2, five discharge abnormality detection means 10 a to 10 e, and five switching means 23 a to 23 e. The five inkjet heads 100 a to 100 e are provided with one drive waveform generating means 18 1 and one storage means 62. Since each component has already been described in the description of FIG. 27, the description thereof will be omitted, and the connection thereof will be described.

As in the case shown in FIG. 27, the ejection selection means 182 corresponds to each of the inkjet heads 100 a to 100 e based on the print data (ejection data) input from the host computer 8 and the clock signal CLK. The print data to be printed is latched in the latch circuit 182b, and an ink jet corresponding to the print data is generated according to the drive signal (voltage signal) input from the drive waveform generating means 181 to the dryino 182c. The electrostatic actuator 120 of the heads 100a to 100e is driven. The drive / detection switching signal is input to the switching units 23 a to 23 e corresponding to all the inkjet heads 100 a to 100 e, respectively, and the switching unit 2 3a to 23e are the drive signals to the inkjet head 120 of the inkjet head 100 based on the drive / detection switching signal regardless of the presence or absence of the corresponding print data (ejection data). After that, the connection with the ink jet head 100 is switched from the drive waveform generating means 18 1 to the ejection abnormality detecting means 10 a to 10 e.

After detecting and judging the ejection abnormality of each of the inkjet heads 100a to 100e by all the ejection abnormality detection means 100a to 100e, all the ink jet heads obtained in the detection processing are determined. The determination results of 100a to 100e are output to the storage means 62, and the storage means 62 determines whether or not there is a discharge abnormality of each of the inkjet heads 100a to 100e and the cause of the discharge abnormality in a predetermined manner. Store in the storage area.

As described above, in the ink jet printer 1 shown in FIG. 28, a plurality of ejection abnormality detecting means 10 a to 10 corresponding to the nozzles 110 of the plurality of inkjet heads 100 a to 100 e, respectively. e, the switching operation is performed by a plurality of switching means 23a to 23e corresponding to them, and the discharge abnormality is detected and its cause is determined. In addition, the discharge abnormality can be detected and its cause can be determined.

FIG. 29 shows an example of the evening detection of ejection abnormality detection of a plurality of ink jet heads 100 (when the number of ejection abnormality detection means 10 is the same as the number of ink jet heads 100 and there is print data). When the discharge abnormality is detected at the same time). The ink jet printer 1 shown in FIG. 29 is obtained by adding (adding) switching control means 19 to the configuration of the ink jet printer 1 shown in FIG. In the present embodiment, the switching control means 19 is composed of a plurality of AND circuits (logical product circuits) AND a—AND e, and print data input to each of the ink jet heads 100 a to 100 e. And a driving-no-detection switching signal, a high-level output signal is output to the corresponding switching means 23a to 23e. It is.

Each of the switching means 23a to 23e detects a corresponding discharge abnormality from the drive waveform generating means 181, based on the output signal of the corresponding AND circuit ANDa to ANDe of the switching control means 19. The connection between the corresponding ink jet heads 100a to 100e and the electrostatic actuator 120 is switched to the means 10a to 10e. Specifically, when the output signals of the corresponding AND circuits AND a to AND e are at the high level, that is, when the drive / detection switching signal is at the high level, the corresponding ink jet head 100 a When the print data input to 1100e is output from the latch circuit 182b to the driver 182c, the switching means 23a〜23e corresponding to the AND circuit switches to the corresponding ink jet. The connection to the pads 100a to 100e is switched from the drive waveform generation means 181 to the ejection abnormality detection means 10a to 10e.

The ejection failure detection means 10a to 10e corresponding to the ink jet head 100 to which the print data was input detected the presence or absence of the ejection failure of each inkjet head 100 and the cause thereof in the case of the ejection failure. Thereafter, the ejection abnormality detection means 10 outputs the determination result obtained in the detection processing to the storage means 62. The storage unit 62 stores one or a plurality of determination results input (obtained) in this way in a predetermined storage area.

As described above, in the ink jet printer 1 shown in FIG. 29, the plurality of ejection abnormality detecting means 10a to l correspond to the nozzles 110 of the plurality of inkjet heads 100a to 100e, respectively. 0e is provided, and when a print data corresponding to each of the ink jet heads 100a to 100e is input from the host computer 8 to the ejection selection means 182 via the control unit 6, the switching control is performed. Since only the switching means 23 a to 23 e specified by the means 19 perform the predetermined switching operation to detect the discharge abnormality of the ink jet head 100 and determine the cause thereof, the discharge driving is performed. This is for the inactive inkjet head 100. Thus, the ink jet printer 1 can avoid useless detection and determination processing.

Fig. 30 shows an example of the timing of ejection abnormality detection of a plurality of ink jet heads 100 (the number of ejection abnormality detection means 100 is the same as the number of ink jet heads 100, and each inkjet head This is the case where the discharge abnormality is detected by circulating through 100). In the ink jet printer 1 shown in FIG. 30, in the configuration of the ink jet printer 1 shown in FIG. 29, one ejection abnormality detecting means 10 is used, and the drive / detection switching signal is scanned (detection / determination processing). (Ink heads 100 for executing the operations are specified one by one.) The switching selecting means 19 a is added.

The switching selection means 19a is provided to the switching control means 19 shown in FIG. 29 by a plurality of inkjet heads 100a to 100a based on a scanning signal (selection signal) input from the control unit 6. : AND circuit corresponding to LOO e Driving to AND a to AND e Scan (select and switch) the input of the Z detection switching signal. The order of scanning (selection) of the switching selection means 19a may be the order of printing data input to the shift register 18a, that is, the order of ejection of the plurality of inkjet heads 100. However, simply a plurality of inkjet heads 100a to: may be in the order of LOOe.

When the scanning order is the order of the print data input to the shift register 18 2 a, when the print data is input to the shift register 18 2 a of the ejection selecting means 18 2, the print data is latched by the latch circuit 1. The signal is latched at 82 b and output to driver 18 c by the input of the latch signal. A scan signal for specifying the ink jet head 100 corresponding to the print data in synchronization with the input of the print data to the shift register 18a or the input of the latch signal to the latch circuit 18b. Is input to the selector 191 of the switching selection means 19a, and a drive Z detection switching signal is output to the corresponding AND circuit. The corresponding AND circuit performs a logical AND operation on the print data input from the latch circuit 18 2 b and the drive / detection switching signal input from the selector 19 1, to output a high-level output signal. Output to the corresponding switching means 23. The switching means 23 to which the high-level output signal has been input from the switching selection means 19a connects the connection of the corresponding inkjet head 100 to the electrostatic actuator 120 by the drive waveform. The generation means 18 1 is switched to the discharge abnormality detection means 10.

The ejection failure detection means 100 detects the ejection failure of the ink jet head 100 to which the print data has been input, and if there is an ejection failure, determines the cause, and stores the determination result in the storage means 62. Output. Then, the storage means 62 stores the thus input (obtained) determination result in a predetermined storage area.

When the scanning order is a simple ink jet head 100a to 100e, when a print data is input to the shift register 18a of the ejection selecting means 1822. The print data is latched by the latch circuit 18b and output to the driver 18c by input of the latch signal. Scan to specify the inkjet head 100 corresponding to the print data in synchronization with the input of the print data to the shift register 18a or the input of the latch signal to the latch circuit 18b. Selection) The signal is input to the selector 191 of the switching selection means 19a, and the drive Z detection switching signal is output to the corresponding AND circuit.

Here, when the print data for the inkjet head 100 determined by the scanning signal input to the selector 191 of the switching selection means 19a is input to the shift register 1822a, The output signal of the corresponding AND circuit becomes High level, and the switching means 23 switches the connection to the corresponding inkjet head 100 from the drive waveform generation means 18 1 to the ejection abnormality detection means 10. However, when the print data is not input to the shift register 18a, the output signal of the AND circuit is at the low level, and The switching means 23 does not execute a predetermined switching operation.

When the switching operation is performed by the switching unit 23, similarly to the above, the ejection abnormality detection unit 10 detects the ejection abnormality of the ink head 100 to which the print data is input, and outputs the ejection abnormality. If there is, after determining the cause, the result of the determination is output to the storage means 62. Then, the storage unit 62 stores the thus input (obtained) determination result in a predetermined storage area.

If there is no print data for the ink jet head 100 specified by the switching selection means 19a, as described above, the corresponding switching means 23 does not execute the switching operation, and therefore, a discharge error occurs. It is not necessary to execute the ejection abnormality detection processing by the detection means 10, but such processing may be executed. If the ejection failure detection processing is executed without performing the switching operation, the determination means 20 of the ejection failure detection means 10 determines whether the corresponding ink jet head 1 0 0, as shown in the flowchart of FIG. The nozzle 110 is determined to be a non-ejection nozzle (step S306), and the determination result is stored in a predetermined storage area of the storage means 62.

Thus, in the ink jet printer 1 shown in FIG. 30, unlike the ink jet printer 1 shown in FIG. 28 or FIG. 29, a plurality of ink heads 100 a to 100 Only one ejection abnormality detecting means 10 is provided for each nozzle 110 of e, and print data corresponding to each of the ink jet heads 100 a to 100 e is sent from the host computer 8 to the control unit 6. , And at the same time, it corresponds to the ink jet head 100 which is specified by the scan (select) signal and performs the discharge drive operation in accordance with the printing data. Since only the switching means 23 performs the switching operation to detect the discharge abnormality of the corresponding ink jet head 100 and determine the cause thereof, each of the heads 35 of the head unit 35 is more efficiently operated. Abnormal discharge detection and its cause A cause determination can be made.

Also, unlike the ink jet printer 1 shown in FIG. 28 or FIG. Since the ink jet printer 1 shown in FIG. 30 only needs to have one ejection failure detecting means 10, the ink jet printer 1 shown in FIG. 28 and FIG. The circuit configuration of the printer 1 can be scaled down, and the manufacturing cost can be prevented from increasing.

Next, the operation of the printer 1 shown in FIGS. 27 to 30, that is, the ejection abnormality detection processing (mainly, detection timing) in the ink jet printer 1 including the plurality of ink jet heads 100 will be described. . Discharge abnormality detection / judgment processing (processing for multiple nozzles) detects residual vibration of diaphragm 122 when ink droplet ejection operation of electrostatic actuator 120 of each inkjet head 100 is performed. Then, based on the period of the residual vibration, whether or not a discharge abnormality (dot missing, ink droplet non-discharge) has occurred for the corresponding inkjet head 100, and a dot missing (ink droplet non-discharge) occurs. If so, the cause is determined. As described above, according to the present invention, these detection / determination processes can be performed if the ink jet head 100 performs an ink droplet (droplet) discharge operation. However, the ink jet head 100 discharges the ink droplets. This is not only the case where printing (printing) is actually performed on the recording paper P, but also the case where a flashing operation (preliminary ejection or preliminary ejection) is performed. Hereinafter, the discharge abnormality detection / judgment process (multiple nozzles) will be described for these two cases. Here, the flushing (preliminary ejection) processing is performed when a cap (not shown in FIG. 1) is attached or at a place where ink droplets (droplets) do not fall on the recording paper P (media). This is a head cleaning operation of discharging ink droplets from all or target nozzles 110 of No. 5. This flushing process (flushing operation) is performed, for example, when periodically discharging the ink in the cavity 141, in order to maintain the ink viscosity in the nozzle 110 within a proper range. Alternatively, it is also performed as a recovery operation when the ink thickens. In addition, the flushing process marks the ink cartridge 31 This is also carried out when ink is initially filled into the cavities 14 1 after being attached to the character means 3.

In addition, in order to clean the nozzle plate (nozzle surface) 150, a wiping process (adhering matter (paper dust, dust, etc.) adhering to the head surface of the printing means 3) is performed using a However, there is a possibility that the inside of the nozzle 110 becomes negative pressure, and ink of another color (other kind of liquid droplet) is drawn in at this time. Therefore, after the wiping process, the flushing process is also performed to discharge a fixed amount of ink droplets from all the nozzles 110 of the head unit 35. Further, the flushing process can be performed in a timely manner in order to maintain the state of the meniscus of the nozzle 110 normally and to ensure good printing.

First, the discharge abnormality detection / judgment process during the flushing process will be described with reference to the flowcharts shown in FIGS. These flow charts will be described with reference to the block diagrams of FIGS. 27 to 30 (the same applies to the printing operation hereinafter). FIG. 31 is a flowchart showing the timing of detecting an ejection abnormality during the flushing operation of the inkjet printer 1 shown in FIG.

When the flushing process of the ink jet printer 1 is executed at a predetermined timing, the ejection abnormality detection / determination process shown in FIG. 31 is executed. The control section 6 inputs the ejection data for one nozzle to the shift register 182a of the ejection selection means 182 (step S401), and the latch signal is input to the latch circuit 182b. (Step S402) This discharge data is latched. At that time, the switching means 23 connects the electrostatic work 120 of the inkjet head 100, which is the object of the ejection data, to the drive waveform generation means 18 1 (step S40). 3).

Then, the ink that has performed the ink ejection operation is For the jet head 100, a discharge abnormality detection / determination process shown in a flowchart of FIG. 24 is executed (step S404). In step S405, the control unit 6 controls all the ink jet heads of the ink jet printer 1 shown in FIG. 27 based on the ejection data output to the ejection selecting means 182. It is determined whether or not the ejection abnormality detection / determination process has been completed for the nozzles 110 of 100 a to 100 e. When it is determined that these processes have not been completed for all the nozzles 110, the control unit 6 sets the shift register 18 2a corresponding to the nozzle 110 of the next ink jet head 100. Input the ejection data to be performed (step S 406), shift to step S 402, and repeat the same processing.

If it is determined in step S405 that the above-described ejection abnormality detection and determination processing has been completed for all nozzles 110, the control unit 6 inputs a CLEAR signal to the latch circuit 18b. Then, the latch state of the latch circuit 18b is released, and the discharge abnormality detection / determination process in the ink jet printer 1 shown in FIG. 27 ends.

As described above, in the ejection abnormality detection / determination process in the printer 1 shown in FIG. 27, the detection circuit is composed of one ejection abnormality detection unit 10 and one switching unit 23, The discharge abnormality detection processing and the determination processing are repeated by the number of the ink jet 100, but the circuit constituting the discharge abnormality detection means 100 has an effect that it does not become so large.

Next, FIG. 32 is a flowchart showing the timing of ejection abnormality detection during the flushing operation of the ink jet printer 1 shown in FIGS. 28 and 29. Although the ink jet printer 1 shown in FIG. 28 and the ink jet printer 1 shown in FIG. 29 have slightly different circuit configurations, the number of the ejection abnormality detecting means 10 and the number of the switching means 23 are different from those of the ink jet head 10. Matches at points corresponding to (same as) the number 0. Therefore, abnormal discharge during flushing operation The detection / judgment process includes the same steps.

At the predetermined evening, when the first flushing process is performed, the control unit 6 inputs ejection data for all nozzles to the shift register 18 a of the ejection selection unit 18. In step S501), a latch signal is input to the latch circuit 18b (step S502), and the ejection data is latched. At that time, the switching means 23a to 23e connect all the ink jet heads 100a to 100e to the drive waveform generating means 181, respectively (step S503).

Then, the ejection abnormality detecting means 100 a to 100 e corresponding to each of the ink jet heads 100 a to 100 e provides the ink jet heads 100 having performed the ink ejection operation with respect to all the ink jet heads 100. The discharge abnormality detection / determination process shown in the flowchart of FIG. 24 is executed in parallel (step S504). In this case, the determination results corresponding to all the ink jet heads 100a to 100e are associated with the inkjet head 100 to be processed, and are stored in a predetermined storage area of the storage means 62. (Step S107 in FIG. 24).

Then, in order to clear the ejection data latched in the latch circuit 18 2 b of the ejection selection means 18 2, the control unit 6 inputs the CLEAR signal to the latch circuit 18 2 b (step S 505) Then, the latch state of the latch circuit 18b is released, and the discharge abnormality detection processing and the determination processing in the ink jet printer 1 shown in FIGS. 28 and 29 are ended.

As described above, in the processing in the printer 1 shown in FIGS. 28 and 29, a plurality of (five in this embodiment) ejection abnormality detections corresponding to the ink heads 100a to 100e are performed. Since the detection and judgment circuit is constituted by the means 10 and the plurality of switching means 23, the discharge abnormality detection / judgment processing can be executed in a short time for all the nozzles 110 at a time. Has an effect.

Next, FIG. 33 shows the flashing of the inkjet printer 1 shown in FIG. 6 is a flowchart showing a timing of detecting a discharge abnormality during a switching operation. Similarly, the ejection abnormality detection process and the cause determination process during the flushing operation will be described using the circuit configuration of the ink jet printer 1 shown in FIG.

When the flushing process of the inkjet printer 1 is executed at a predetermined timing, first, the control unit 6 outputs a scanning signal to the selector 191 of the switching selecting unit 19a, and the switching selecting unit 19a Thus, the first switching means 23a and the ink jet head 100a are set (specified) (step S601). Then, ejection data for all nozzles is input to the shift register 182a of the ejection selection means 182 (step S602), and a latch signal is input to the latch circuit 182b (step S603). This ejection data is latched. At this time, the switching means 23a connects the electrostatic work 120 of the ink jet head 100a with the drive waveform generating means 181 (step S604).

Then, for the ink jet head 100a that has performed the ink discharge operation, a discharge abnormality detection / determination process shown in the flow chart of FIG. 24 is executed (step S605). In this case, in step S103 of FIG. 24, the drive / detection switching signal, which is the output signal of the selector 191, and the ejection data are input to the AND circuit ANDa, and the output signal of the AND circuit ANDa is output. When the high level is reached, the switching means 23a connects the electrostatic work 120 of the inkjet head 100a to the discharge abnormality detection means 10 with each other. Then, the determination result of the discharge abnormality determination process executed in step S106 of FIG. 24 is associated with the inkjet head 100 (here, 100a) to be processed, and stored in the storage unit 62. The data is stored in a predetermined storage area (step S107 in FIG. 24).

In step S 606, the control unit 6 performs all the discharge abnormality detection and determination processing. It is determined whether or not the processing has been completed for all the nozzles. If it is determined that the ejection abnormality detection / judgment process has not been completed for all nozzles yet,

The control unit 6 outputs the scanning signal to the selector 191 of the switching selecting means 19a, and the switching selecting means 19a causes the next switching means 23b and the ink jet head 100b. Is set (identified) (step S607), and the process proceeds to step S603 to repeat the same processing. Hereinafter, this loop is repeated until the ejection abnormality detection / determination processing is completed for all the ink jet heads 100. In step S606, the ejection abnormality detection processing and the determination processing are completed for all nozzles 110. If it is determined that the ejection data has been cleared, the control unit 6 sends the CLEAR signal to the latch circuit 18 2 in order to clear the ejection data latched in the latch circuit 18 2 b of the ejection selection means 18 2. b (step S609) to release the latch state of the latch circuit 18b, and terminate the discharge abnormality detection processing and determination processing in the ink jet printer 1 shown in FIG. You.

As described above, in the processing in the ink jet printer 1 shown in FIG. 30, the detection circuit is composed of the plurality of switching means 23 and one ejection abnormality detection means 10, and the selector of the switching selection means 19 a Only the switching means 23 corresponding to the ink jet head 100, which is specified by the scanning signal of 191 and drives the discharge in accordance with the discharge data, performs the switching operation and discharges the corresponding inkjet head 100. Since the abnormality detection and the cause determination are performed, the discharge abnormality detection and the cause determination of each ink jet head 100 can be more efficiently performed.

In step S602 of this flowchart, the ejection data corresponding to all the nozzles 110 is input to the shift register 182a. As described above, according to the scanning order of the inkjet head 100 by the switching selecting means 19a, the discharge inputted to the shift register 182a is adjusted. The output data may be input to a corresponding one of the ink jet heads 100, and ejection abnormality detection / determination processing may be performed for each nozzle 110.

Next, with reference to the flowcharts shown in FIGS. 34 and 35, a description will be given of the ejection abnormality detection / determination processing of the ink jet printer 1 during the printing operation. The ink jet printer 1 shown in FIG. 27 is mainly suitable for the ejection abnormality detection processing and the judgment processing at the time of the flushing operation. Therefore, the flowchart at the time of the printing operation and the description of the operation are omitted. In the inkjet printer 1 shown in FIG. 7, the ejection failure detection / determination process may be performed during the printing operation.

FIG. 34 is a flowchart showing the timing of detecting an ejection failure during the printing operation of the ink jet printer 1 shown in FIGS. 28 and 29. The process of this flowchart is executed (started) by a print (print) instruction from the host computer 8. When the print data is input from the host computer 8 to the shift register 18 2 a of the ejection selection means 18 2 via the control unit 6 (step S 7 01), the data is sent to the latch circuit 18 2 b. When the latch signal is input (step S702), the print data is latched. At this time, switching means 2 3 a ~

23 e connects all the ink jet heads 100 a to 100 e to the drive waveform generating means 18 1 (step S 703).

Then, the ejection failure detecting means 10 corresponding to the ink jet head 100 that has performed the ink ejection operation executes the ejection failure detection 'determination process shown in the flowchart of FIG. 24 (step S704). . In this case, each determination result corresponding to each inkjet head 100 is stored in a predetermined storage area of the storage means 62 in association with the target inkjet head 100 to be processed.

Here, in the case of the ink jet printer 1 shown in FIG.

3a to 23e are based on the drive / detection switching signal output from the control unit 6, The inkjet heads 100a to 100e are connected to the ejection abnormality detecting means 100a to 100e (step S103 in FIG. 24). Therefore, since the electrostatic actuator 120 is not driven in the ink jet head 100 where print data does not exist, the residual vibration detecting means 16 of the discharge abnormality detecting means 10 is provided with the diaphragm 1 2 Does not detect 1 residual vibration waveform. On the other hand, in the case of the ink jet printer 1 shown in FIG. 29, the switching means 23 a to 23 e include the drive Z detection switching signal output from the control unit 6 and the output from the latch circuit 18 2 b. Based on the output signal of the AND circuit to which the print data is input, the ink jet head 100 where the print data exists is connected to the discharge abnormality detecting means 10 (step S 1.03 in FIG. 24). ).

In step S705, the control unit 6 determines whether or not the printing operation of the inkjet printer 1 has been completed. When it is determined that the printing operation has not been completed, the control unit 6 proceeds to step S701, inputs the next printing data to the shift register 182a, and performs the same processing. repeat. When it is determined that the printing operation has been completed, the control unit 6 latches the CLEAR signal in order to clear the ejection data latched in the latch circuit 18 b of the ejection selection unit 18. Input to the circuit 18 2 b (step S 706), release the latch state of the latch circuit 18 2 b, and detect the discharge abnormality in the ink jet printer 1 shown in FIGS. 28 and 29. The processing and the determination processing are terminated. As described above, the inkjet printer 1 shown in FIGS. 28 and 29 includes a plurality of switching units 23 a to 23 e and a plurality of ejection abnormality detection units 10 a to 10 e. Since the ejection abnormality detection / judgment process is performed for all the ink jet heads 100 at a time, these processes can be performed in a short time. In addition, the ink jet printer 1 shown in FIG. 29 further includes a switching control means 19, that is, AND circuits AND a to AND e for performing a logical AND operation of the drive / detection switching signal and the print data, and performs a printing operation. Do the ink jet head 1 0 0 Since the switching operation by the switching unit 23 is performed only for the ejection failure, the ejection abnormality detection processing and the determination processing can be performed without performing useless detection.

Next, FIG. 35 is a flowchart showing the timing of detecting an ejection abnormality during the printing operation of the inkjet printer 1 shown in FIG. In response to a print instruction from the host computer 8, the process of this flowchart is executed in the inkjet printer 1 shown in FIG. First, the switching selection means 19a sets (specifies) the first switching means 23a and the ink jet head 100a in advance (step S801).

When print data is input from the host computer 8 to the shift register 182a of the ejection selection means 182 via the control unit 6 (step S802), a latch signal is input to the latch circuit 182b (step S802). S803), the print data is latched. Here, at this stage, the switching means 23 a to 23 e include all the ink jet heads 100 a to 100 e and the drive waveform generation means 18 1 (the driver 18 2 of the ejection selection means 182). c) (step S804).

Then, when there is print data in the inkjet head 100a, the control unit 6 connects the electrostatic actuator 120 after discharge operation to the discharge abnormality detection means 10 by the switching selection means 19a ( The discharge abnormality detection / determination process shown in the flowchart of FIG. 24 (steps S103) and FIG. 24 (FIG. 25) is executed (step S805). Then, the determination result of the ejection abnormality determination process executed in step S106 of FIG. 24 is associated with the inkjet head 100 (here, 100a) to be processed, and stored in the storage unit 62. The data is stored in a predetermined storage area (step S107 in FIG. 24).

In step S806, the control unit 6 determines whether or not the above-described ejection failure detection and determination process has been completed for all nozzles 110 (all inkjet heads 100). Then, the above process is performed for all nozzles 110. If it is determined that the processing has been completed, the control unit 6 sets the switching means 23a corresponding to the first nozzle 110 based on the scanning signal (step S808), and If it is determined that the above process has not been completed for all nozzles 110, the switching means 23b corresponding to the next nozzle 110 is set (step S807).

In step S809, the control section 6 determines whether or not the predetermined printing operation instructed from the host computer 8 has been completed. If it is determined that the printing operation has not been completed, the next print data is input to the shift register 18a (step S802), and the same processing is repeated. If it is determined that the printing operation has been completed, the controller 6 clears the CLEAR signal to clear the ejection data latched in the latch circuit 18 2 b of the ejection selection means 18 2. (Step S810) to release the latch state of the latch circuit 18b, and perform the discharge abnormality detection and judgment process in the ink jet printer 1 shown in Fig. 30. finish.

As described above, the droplet discharge device (ink jet printer 1) of the present invention includes a vibration plate 121, an electrostatic actuator 120 for displacing the vibration plate 121, and an inside thereof. The cavity is filled with liquid, and the displacement of the diaphragm 1 2 1 changes (increases or decreases) the pressure inside the cavity 14 1, and communicates with the cavity 14 1 to change the pressure inside the cavity 14 1 (increase / decrease) ), A plurality of ink jet heads (droplet discharge heads) 100 having nozzles 110 for discharging liquid as liquid droplets, and a drive waveform generation for driving these electrostatic actuators 120 Means 181, an ejection selection means 182 for selecting which nozzle 110 of the plurality of nozzles 110 to eject a droplet, and a residual vibration of the diaphragm 121, Based on the detected residual vibration of the diaphragm 12 1, an abnormality in droplet ejection is detected. One or a plurality of ejection abnormality detection means 10 and a drive / detection switching signal and printing data after a droplet ejection operation by driving the electrostatic actuator 120 Or a switching means 23 for switching the electrostatic function 120 from the driving waveform generating means 18 1 to the discharge abnormality detecting means 10 based on the scanning signal. It was decided to detect discharge abnormalities of a plurality of nozzles 110 either sequentially or sequentially.

Therefore, according to the droplet ejection apparatus and the ejection failure detection / determination method of the droplet ejection head of the present invention, the ejection failure detection and the cause determination thereof can be performed in a short time, and the detection including the ejection failure detection means 10 The circuit configuration of the circuit can be scaled down, and an increase in the manufacturing cost of the droplet discharge device can be prevented. In addition, after the electrostatic actuator 120 is driven, the discharge abnormality detection means 10 is switched to discharge abnormality detection and cause determination, so that the drive of the actuator is not affected. Thus, the throughput of the droplet discharge device of the present invention is not reduced or deteriorated. In addition, it is also possible to equip the existing droplet discharge device (inkjet printer) having predetermined components with the discharge abnormality detection means 10.

Further, unlike the above configuration, the droplet discharge device of the present invention includes a plurality of switching means 23, a switching control means 19, and a plurality of ejection abnormality detecting means 1 corresponding to one or the number of nozzles 110. 0 and a corresponding electrostatic actuator based on the drive / detection switching signal and ejection data (print data) or the scanning signal, drive Z detection switching signal and ejection data (print data). By switching from 120 to the drive waveform generation means 18 1 or the ejection selection means 18 2 to the ejection abnormality detection means 10, ejection abnormality detection and cause determination are performed.

Therefore, according to the droplet discharge apparatus of the present invention, the switching means corresponding to the electrostatic actuator 120 which does not receive the ejection data (print data), that is, does not perform the ejection driving operation, performs the switching operation. Since it is not, useless detection and judgment processing can be avoided. Further, when the switching selection means 19a is used, the droplet discharge device only needs to have one discharge abnormality detection means 10 only. Therefore, the circuit configuration of the droplet discharge device can be scaled down, and the manufacturing cost of the droplet discharge device can be prevented from increasing.

Next, the ink jet head 100 (head unit 35) in the droplet discharge apparatus according to the present invention is configured to execute a recovery process for eliminating the cause of the discharge abnormality (head abnormality) (recovery means 2). 4) will be described. FIG. 36 is a diagram showing a schematic structure (partially omitted) as viewed from above the ink jet printer 1 shown in FIG. In addition to the configuration shown in the perspective view of FIG. 1, the ink jet printer 1 shown in FIG. 36 has a wiper 300 and a cap 310 for executing a recovery process for ink droplet non-ejection (head abnormality). Is provided.

The recovery process performed by the recovery unit 24 includes a flushing process for preliminary discharging droplets from the nozzle 110 of each inkjet head 100 and a wiper 300 (see FIG. 37) described later. This includes a wiping process and a pumping process (pump suction process) using a tube pump 320 described later. That is, the recovery means 24 includes a tube pump 320 and a pulse motor for driving the tube pump 320, a vertical drive mechanism for the wiper 300 and the wiper 300, and a vertical drive mechanism for the cap 310. (Not shown), and the head driver 33 and the head unit 35 function in the flushing process, and the carriage motor 41 functions as a part of the recovery unit 24 in the wiping process. . Since the flushing process has been described above, the wiping process and the pomming process will be described below.

Here, the wiping process refers to a process of wiping foreign matter such as paper dust adhered to the nozzle plate 150 (nozzle surface) of the head unit 35 with the wiper 300. The bombing process (pump suction process) is a process in which a tube pump 320 described later is driven to suck and discharge ink in the cavity 144 from each nozzle 110 of the head unit 35. Refers to processing. As described above, the wiping process is performed by the droplet of the inkjet head 100 described above. This process is appropriate as a recovery process in the state of paper dust adhesion, which is one of the causes of discharge abnormalities. In addition, the pump suction process removes air bubbles in the cavity 141 that cannot be removed by the flushing process described above, or the ink around the nozzle 110 is dried or the ink in the cavity 141 deteriorates over time. This is an appropriate process as a recovery process to remove the thickened ink when the viscosity increases due to. If the viscosity is not so increased and the viscosity is not so large, the above-described recovery process by the flushing process may be performed. In this case, since the amount of discharged ink is small, appropriate recovery processing can be performed without reducing throughput / running cost.

A printing unit 3 having a plurality of head units 35 is mounted on a carriage 32, guided by two carriage guide shafts 42, and connected by a carriage motor 41 at the upper end thereof in the figure. It moves in connection with the timing belt 4 2 1 via the section 3 4. The printing means 3 mounted on the carriage 32 can move in the main scanning direction (in conjunction with the timing belt 421) via the timing belt 421 which is moved by driving the carriage motor 41. The carriage motor 41 plays a role of a pulley for continuously rotating the timing belt 421, and a pulley 44 is similarly provided on the other end side.

The cap 310 is for capping the nozzle plate 150 of the head unit 35 (see FIG. 5). A hole is formed in the bottom surface of the cap 310, and a flexible tube 321, which is a component of the tube pump 320, is connected to the cap 310 as described later. The tube pump 320 will be described later with reference to FIG.

During the recording (printing) operation, the head unit 35 (printing means 3) is moved in the main scanning direction, that is, while the electrostatic inkjet 120 of a predetermined inkjet head 100 (droplet ejection head) is driven. Move to the left and right in Fig. 36, and By moving the recording paper P in the sub-scanning direction, that is, in the downward direction in FIG. 36, the ink jet printer (droplet discharge device) 1 prints the print data (print data) input from the host computer 8. ) Prints (records) a specified image on recording paper P based on).

FIG. 37 is a diagram showing a positional relationship between the wiper 300 and the head unit 35 shown in FIG. In FIG. 37, the head unit 35 and the wiper 300 are shown as a part of a side view of the ink jet printer 1 shown in FIG. As shown in FIG. 37 (a), the wiper 300 is vertically movable so that it can contact the nozzle surface of the printing means 3, that is, the nozzle plate 150 of the head unit 35. Is done.

Here, the wiping process which is the recovery process using the wiper 300 will be described. When performing the wiping process, as shown in FIG. 37 (a), the wiper 300 is driven by a drive unit (not shown) so that the tip of the wiper 300 is located above the nozzle surface (nozzle plate 150). Is moved upward. In this case, when the carriage motor 41 is driven to move the head unit 35 leftward (in the direction of the arrow) in the figure, the wiping member 301 comes into contact with the nozzle plate 150 (nozzle surface). become.

Since the wiping member 301 is made of a flexible rubber member or the like, as shown in FIG. 37 (b), the tip of the wiping member 301 that comes into contact with the nozzle plate 150 is a radius. And clean the surface of the nozzle plate 150 (nozzle surface) with the tip. This makes it possible to remove foreign matter such as paper dust attached to the nozzle plate 150 (nozzle surface) (for example, paper dust, dust floating in the air, and pieces of rubber). In addition, in accordance with the state of such foreign matter attachment (when a large amount of foreign matter is attached), the head unit 35 is reciprocated above the wiper 300 to perform a plurality of wiping processes. It can be carried out twice. FIG. 38 is a diagram showing a relationship between the head unit 35, the cap 310, and the pump 320 during the pump suction process. The tube 321 forms an ink discharge path in a bombing process (pump suction process), and one end thereof is connected to the bottom of the cap 310 as described above, and the other end is a tube pump. It is connected to the ink cartridge 340 via 320.

An ink absorber 330 is arranged on the inner bottom surface of the cap 310. The ink absorber 330 absorbs the ink discharged from the nozzle 110 of the ink jet head 100 during the pump suction processing and the flushing processing, and temporarily stores the ink. In addition, the ink absorbers 330 can prevent the ejected droplets from splashing and contaminating the nozzle plate 150 during the flushing operation into the cap 310. ·

FIG. 39 is a schematic diagram showing a configuration of the tube pump 320 shown in FIG. As shown in FIG. 39 (B), the tube pump 320 is a rotary pump, and includes a rotating body 322 and four ports arranged on the circumference of the rotating body 32-2. And a guide member 350. The rollers 3 2 3 are supported by a rotating body 3 2 2 and press the flexible tube 3 2 1 placed in an arc along the guide 3 5 1 of the guide member 3 50. Things. This tube pump 320 is rotated by rotating the rotating body 322 in the direction of the arrow X shown in FIG. The two rollers 3 23 sequentially press the tubes 3 2 1 placed on the arc-shaped guide 3 5 1 of the guide member 3 50 while rotating in the Y direction. As a result, the tube 3 2 1 is deformed, and the negative pressure generated in the tube 3 2 1 causes the ink (liquid material) in the cavity 14 of each ink jet head 100 to pass through the cap 3 10. Unnecessary ink that has been sucked in, air bubbles have been mixed in, or the viscosity of the ink has increased due to drying is passed through the nozzle 110 and the ink absorber 3 3 The discharged ink is discharged to 0, and the discharged ink absorbed by the ink absorber 330 is discharged to the discharged ink cartridge 340 (see FIG. 38) via the tube pump 320.

The tube pump 320 is driven by a motor such as a pulse motor (not shown). The pulse motor is controlled by the control unit 6. Drive information for the rotation control of the tube pump 320, for example, a look-up table describing the rotation speed and the number of rotations, a control program describing the sequence control, and the like are stored in the PROM 64 of the control unit 6, and the like. The CPU 61 of the control unit 6 controls the tube pump 320 based on the drive information.

Next, the operation of the recovery means 24 (discharge abnormality recovery processing) will be described. FIG. 40 is a flowchart showing an ejection failure recovery process in the ink jet printer 1 (droplet ejection device) of the present invention. In the above-described discharge abnormality detection / determination process (see the flowchart of FIG. 24), the nozzle 110 having the discharge abnormality is detected, and if the cause is determined, a predetermined tie that is not performing a printing operation (printing operation) is performed. When the head unit 35 is in a predetermined standby area (for example, the position where the nozzle plate 150 of the head unit 35 is covered with the cap 310 in FIG. 36 or the wiping process using the wiper 300 can be performed) The discharge abnormal recovery process is executed.

First, the control unit 6 corresponds to each nozzle 110 stored in the EEPROM 62 of the control unit 6 in step S107 of FIG. 24. The determination result is read out (step S910). In step S902, the control unit 6 determines whether or not the readout determination result includes a nozzle 110 having an ejection failure. Then, when it is determined that there is no ejection failure nozzle 110, that is, when the droplets are normally ejected from all the nozzles 110, the ejection abnormality recovery processing is terminated as it is. On the other hand, when it is determined that any of the nozzles 110 has a discharge abnormality, in step S903, the control unit 6 determines that the nozzle 110 determined to have the discharge abnormality has a paper dust adhesion. Is determined. When it is determined that paper dust is not attached near the outlet of the nozzle 110, the process proceeds to step S905, and when it is determined that paper dust is attached, The wiping process for the nozzle plate 150 by the wiper 300 is executed (step S904).

In step S905, the control unit 6 subsequently determines whether or not the nozzle 110 that has been determined to have the above-described ejection abnormality has air bubbles. Then, when it is determined that air bubbles are mixed, the control unit 6 executes a pump suction process by the tube pump 320 for all the nozzles 110 (step S906), and This discharge abnormality recovery processing ends.

On the other hand, if it is determined that there is no air bubble, the control unit 6 sets the pump by the tube pump 320 on the basis of the length of the period of the residual vibration of the diaphragm 121 measured by the measuring unit 17. A flushing process is performed on only the nozzle 110 or all the nozzles 110 determined to be the suction process or the discharge abnormality (step S <b> 907), and the discharge abnormality recovery process ends.

Next, an operation (operation) at the time of power-on (power 電源 N), that is, a process at power-on, which is a main part (feature) of the ink jet printer (droplet discharge device) 1 of the present invention, will be described.

In the inkjet printer 1, when the power is turned on, the residual vibration of the diaphragm 121 is detected, and based on the detected period of the residual vibration of the diaphragm 121 (vibration pattern), the inkjet is performed. The presence / absence of ejection failure (head failure) of the head 100 and the cause of the ejection failure are detected, and a recovery process for eliminating the ejection failure is selected (determined). Then, the selected recovery process is executed.

The detection of the residual vibration of the diaphragm 1 2 1 is performed by idling, that is, the ink droplet (liquid (Drip) 'is driven so that the electrostatic actuator is not driven to discharge the droplet. This makes it possible to detect residual vibration of the diaphragm 122 without consuming ink. That is, compared to the case where the residual vibration of the diaphragm 121 is detected by actually ejecting ink droplets, the amount of ink consumed in the processing at the time of turning on the power (including the abnormal ejection recovery processing) can be reduced. . Further, since no ink droplet is ejected, the above-described detection can be performed regardless of the position of the ink jet head 100.

The basic configuration other than that the electrostatic actuator 120 is driven to the extent that the ink droplet is not ejected to detect the residual vibration of the diaphragm 121 is as described above.

According to the present invention, in the processing at the time of turning on the power, for example, an operation of discharging ink droplets (ink discharging operation) such as flashing is performed, and the residual vibration of the diaphragm 122 is detected. Is also good.

Further, in the present invention, the detection of the residual vibration of the diaphragm 121 after the processing at the time of power-on (for example, during printing) is performed so that the ink droplets are not discharged. May be driven.

Hereinafter, a specific example will be described based on a flowchart.

FIG. 41 is a flowchart showing processing at power-on in the ink jet printer 1 (droplet discharge device) of the present invention. FIG. 42 is a discharge abnormality (head abnormality) determination processing (step ST in the flowchart shown in FIG. 41). FIG. 43 is a flowchart showing a discharge abnormality recovery process (sub routine in step ST106 of the flowchart shown in FIG. 41).

When the power is turned on (when the power is turned on), the processing shown in FIG. 41 is executed. First, the counter is reset, that is, the count value of the count Nf = 0, Np = 0 (step ST 1 0 1). The count value of the countdown N f Is the number of times the flushing process has been performed in the power-on process, and Np is the number of times the pump suction process has been performed in the power-on process.

Next, a discharge abnormality detection / determination process is performed (step ST102). The ejection abnormality detection / determination process is basically the same as the ejection abnormality detection / judgment process described above and shown in FIG. 24, except that the residual vibration of the diaphragm 121 is detected by ejecting ink droplets. Do not drive the electrostatic actuator 120 to the extent that it does not.

The ejection abnormality detection / determination process may be performed, for example, for all of the inkjet heads 100 (nozzles 110), or may be grouped into a plurality of inkjet heads 100, and may be grouped for each group. The representative ink jet head 100 may be set, and the process may be performed on each representative ink jet head 100.

Since the discharge abnormality detection / determination processing shown in FIG. 24 has already been described, here, the discharge abnormality (head abnormality) determination processing (FIG. Only step 24 (corresponding to the discharge abnormality determination process in step S106) will be described with reference to FIG.

As shown in FIG. 42, first, the measurement result, that is, the period Tw of the residual vibration of the diaphragm 121 is input to the determination means 20 (step ST201).

Next, in step ST202, it is determined whether or not the period Tw of the residual vibration exists, that is, whether or not the discharge abnormality detecting means 10 has not obtained the residual vibration waveform data. If it is determined that the residual vibration period Tw does not exist, the inkjet head 100 determines that the residual vibration of the diaphragm 121 has not been detected in the ejection abnormality detection process (the untested head). (Nozzle), and it is determined that reexamination and recovery processing are necessary (step ST206)

If it is determined that the residual vibration waveform data exists, In step ST203, it is determined whether or not the cycle Tw is within a predetermined range Tr recognized as a cycle during normal ejection.

When it is determined that the cycle Tw of the residual vibration is within the predetermined range Tr, the corresponding ink jet head 100 is in a state where the ink droplet can be normally ejected from the nozzle 110 thereof. This means that the inkjet head 100 is determined to be normal (normal ejection) (step ST207). If it is determined that the period Tw of the residual vibration is not within the predetermined range Tr, then, in step ST204, it is determined whether the period Tw of the residual vibration is shorter than the predetermined range Tr. Is determined.

When it is determined that the cycle Tw of the residual vibration is shorter than the predetermined range Tr, it means that the frequency of the residual vibration is high, and as described above, air bubbles are generated in the captivity 141 of the inkjet head 100. Is considered to have been mixed in, and air bubbles are mixed in the cavity 141 of the ink jet head 100 (bubble mixing), and it is determined that a recovery process is necessary (step ST208).

If it is determined that the period Tw of the residual vibration is longer than the predetermined range Tr, then it is determined whether the period Tw of the residual vibration is longer than the predetermined threshold T1 ( Step ST 205). If it is determined that the cycle Tw of the residual vibration is longer than the predetermined threshold T1, it is considered that the residual vibration is excessively damped, and the ink near the nozzle 110 of the ink jet 100 is depressed. Is thickened by drying (drying), and it is determined that a recovery process is necessary (step ST209). Then, in step ST205, when it is determined that the period Tw of the residual vibration is shorter than the predetermined threshold value T1, the period Tw of the residual vibration is in a range that satisfies Tr and Tw <T1. As described above, it is considered that paper powder adheres to the vicinity of the outlet of the nozzle 110, which has a higher frequency than that of drying, and the paper is located near the nozzle 110 of the inkjet head 100. The powder adheres (paper powder adheres), and it is determined that recovery processing is necessary (step ST210). As described above, the determination means 20 determines whether the target inkjet head 100 is in a normal state, and if it is in a discharge abnormality (head abnormality) state, the cause of the discharge abnormality is determined. Then (steps ST206 to ST210), the result of the determination is output to the control section 6, and the discharge abnormality determination processing ends.

The determination result corresponding to each ink jet head 100 is stored in a predetermined storage area of an EEPROM (memory means) 62 of the control unit 6 in association with the ink jet head 100 to be processed.

As shown in FIG. 41, when the discharge abnormality detection / determination processing in step ST102 is completed, it is determined whether or not the discharge abnormality recovery processing is necessary based on the determination result stored in the EEPROM 62. (Step ST103) If the ejection failure recovery processing is not required, that is, if the inkjet head 100 is normal, the printer enters the print standby state in which printing is possible (Step ST104), This processing ends.

On the other hand, if the discharge abnormality recovery processing is required, whether the count value Np of the counter indicating the number of times of the pump suction processing is equal to or less than a preset value a (α is a natural number) (Νρ≤α) Then, if Np is equal to or less than α, the abnormal discharge recovery process is executed (step ST106).

In the ejection failure recovery process, as shown in FIG. 43, first, the determination result corresponding to each nozzle 110 or the representative nozzle 110 stored in the EEPRO M 62 is read (step ST301). .

Next, in step ST302, it is determined whether or not the read determination result indicates that there is no reinspection (inspection nozzle). If it is determined that the reexamination is not required (“NO” in step ST302), that is, if it is determined that the reexamination is necessary (untested nozzle), the ejection abnormality recovery processing is terminated as it is. . On the other hand, if it is determined that there is no re-inspection (“YE S” in step ST 302), that is, if it is determined that the inspection has been completed and the discharge is abnormal, the It is determined whether or not the nozzle 110 that has been determined to have an abnormal discharge has adhering paper powder. When it is determined that paper dust is not attached near the outlet of the nozzle 110, the process proceeds to step ST305, and when it is determined that paper dust is attached, The wiping process for the nozzle plate 150 by the wiper 300 is executed (step ST304).

In step ST 305, subsequently, it is determined whether or not the nozzle 110 that has been determined to have the above-described discharge abnormality contains air bubbles. If it is determined that air bubbles are mixed, the pump suction process is performed by the tube pump 320, and the power supply count value Np is incremented by one (Np = Np + l) (step ST 30 6) The discharge abnormality recovery process ends.

On the other hand, when it is determined that no air bubbles are contained (dry), the count value N f of the counter indicating the number of times of the flushing process is equal to or less than a preset value i3 (| 3 is a natural number) (N f ≤j3 ) Is determined (step ST307), and if Nf is equal to or less than) 3, a flushing process is performed, and the count value Nf of the counter is incremented by one (Nf = Nf + 1) (Step ST 308), this discharge abnormality recovery process ends.

If the ejection abnormality can be eliminated by the flushing process, the ink consumption can be reduced as compared with the case where the pump suction process is performed. If N f is greater than / 3, the pump suction process is performed by the tube pump 320, and the count value Np of the counter is incremented by one (Np = Np + 1) (step ST309), and this discharge is performed. The abnormal recovery processing ends. As described above, when N f is larger than 3, that is, when the flushing process is repeated three times, and the discharge abnormality is not resolved, the pump suction process is selected as the recovery process for eliminating the discharge abnormality (the pump suction process is performed). Change) done and executed As shown in FIG. 41, upon completion of the ejection failure recovery process in step ST106, the process returns to step ST102, and steps ST102 and onward are executed again.

That is, first, in step ST102, an ejection failure detection / determination process is executed to determine whether or not the ejection failure recovery process is necessary (step ST103). If the ejection failure recovery process is not required, If the ejection abnormality is resolved by the ejection abnormality recovery process and the ink jet head 100 becomes normal, or a re-inspection is necessary (untested nozzle), the re-inspection results in the ink jet. When it is determined that the print data 100 is normal, the print standby state is set in which printing can be performed (step ST104), and this processing ends.

On the other hand, when the discharge abnormality recovery processing is necessary, it is determined whether or not the count value Np of the count indicating the number of times of the pump suction processing is not more than α (Νρ≤α), and Νρ is not more than a. In the case of, the above-mentioned discharge abnormality recovery processing is executed (step ST106). If ρρ is larger than Q !, an error message is displayed on the display section 操作 of the operation panel 7, and the operation is stopped (step ST106). ST 1 0 7), ends this process.

That is, if the discharge abnormality is not resolved even after performing the pump suction process α times, it is determined that the discharge abnormality is difficult to be resolved, and the discharge abnormality recovery process is not performed. Then, on the display unit M ', for example, an error message indicating that the discharge abnormality is not resolved or a message urging repair is displayed.

In the flushing process, for example, the following two methods (1) and (2) can be considered.

(1) Ink jet heads 100 of each representative are inspected, and if one of them has an inkjet head 100 that requires flushing, flushing is performed on all ink jet heads 100. I do. (2) Inspect all inkjet heads 100 and perform flushing only on ink jet heads 100 that require flushing. As described above, according to inkjet printer 1, power supply In the process at the time of loading, the presence or absence of discharge abnormalities (head abnormalities) and the cause of discharge abnormalities are detected (determined) based on the period (vibration pattern) of the residual vibration of the diaphragm 121. The presence or absence of a discharge abnormality and the cause of the discharge abnormality can be reliably detected, and appropriate (optimal) recovery processing can be performed according to the cause of the discharge abnormality. As a result, the ink jet printer 1 can be brought into a normal state in which printing can be performed, and ink consumption more than necessary can be prevented (the amount of discharged ink can be reduced).

In addition, since the presence or absence of discharge abnormalities and the cause of discharge abnormalities are detected based on the period (vibration pattern) of the residual vibration of the diaphragm 122, other devices such as a timer must be provided separately for the detection. There is no. Therefore, the structure is simple, the number of parts is reduced, which is advantageous for miniaturization, and the cost can be reduced. Further, in the inkjet printer 1, even after the process at the time of turning on the power is completed (for example, during printing), the cause of the discharge abnormality can be determined, and the cause of the discharge abnormality can be determined. Since it is possible to execute appropriate recovery processing (either flushing processing, pump suction processing, or wiping processing or two), unlike the sequential recovery processing in the conventional droplet discharge device, the recovery processing is performed. It is possible to reduce wasteful waste ink generated when the printing is performed, thereby preventing a decrease or deterioration of the throughput of the entire inkjet printer 1.

Also, compared to the conventional droplet ejection device that can detect ejection abnormalities, it does not require other components (for example, an optical dot missing detection device, etc.), so the ink jet head 100 (head unit) 3 5) Finally, the ink jet pudding In addition to being able to detect discharge abnormalities without increasing the overall size of the printer 1, the manufacturing cost of the inkjet printer 1 that can detect discharge abnormalities (missing dots) can be reduced.

Further, since the discharge abnormality is detected using the residual vibration of the diaphragm 121 after the ink droplet discharge operation, the discharge abnormality can be detected even during the printing operation. In the present invention, the notification unit is not limited to the display unit (display unit). In addition, as the notification unit, for example, a light emitting unit such as a lamp, a device that emits a buzzer, sound, or the like may be used. . <Second embodiment>

Next, another configuration example of the ink jet head according to the present invention will be described. FIG. 44 to FIG. 47 are cross-sectional views each schematically showing another configuration example of the ink jet head (head unit). Hereinafter, the description will be made based on these drawings, but the description will be focused on the points different from the above-described embodiment, and the description of the same matters will be omitted.

In the ink jet head 100 A shown in FIG. 44, the vibration plate 212 vibrates by driving the piezoelectric element 200, and the ink (liquid) in the cavity 208 is ejected from the nozzle 203. To do. A stainless steel metal plate 204 is joined to the stainless steel nozzle plate 202 with the nozzle (hole) 203 formed thereon through an adhesive film 205. In addition, a similar stainless steel metal plate 204 is joined via an adhesive film 205. A communication port forming plate 206 and a cavity plate 207 are sequentially bonded thereon.

The nozzle plate 202, the metal plate 204, the adhesive film 205, the communication port forming plate 206, and the cavity plate 206 each have a predetermined shape (a shape in which a concave portion is formed). Molded, and by stacking these A cavity 208 and a reservoir 209 are formed. The cavity 208 and the reservoir 209 communicate with each other via an ink supply port 210. Further, the reservoir 209 communicates with the ink intake port 211.

A diaphragm 2 12 is installed in the upper opening of the cavity plate 2 07, and a piezoelectric element 200 is joined to the diaphragm 2 12 via a lower electrode 2 13. Have been. An upper electrode 214 is joined to the piezoelectric element 200 on the side opposite to the lower electrode 211. The head driver 210 includes a drive circuit that generates a drive voltage waveform, and applies (supplies) a drive voltage waveform between the upper electrode 214 and the lower electrode 213 to thereby generate the piezoelectric element 200. Vibrates, and the diaphragm 2 1 2 joined thereto vibrates. The volume of the cavity 208 (pressure in the cavity) changes due to the vibration of the diaphragm 210, and the ink (liquid) filled in the cavity 208 is ejected as droplets from the nozzle 203. . The amount of liquid reduced in the cavity 208 due to the ejection of the liquid droplets is supplied by supplying ink from the reservoir 209. In addition, ink is supplied to the reservoir 209 from the ink intake port 211.

In the same manner as described above, the ink jet head 100B shown in FIG. 45 also discharges ink (liquid) in the cavity 22 from the nozzles by driving the piezoelectric element 200. This inkjet head 100B has a pair of opposed substrates 220, and a plurality of piezoelectric elements 200 are intermittently arranged at predetermined intervals between the two substrates 220.

A cavity 2 21 is formed between adjacent piezoelectric elements 200. A plate (not shown) is installed at the front in FIG. 4 5 of the cavity 2 2 1, and a nozzle plate 2 2 2 is installed at the rear, and the nozzle corresponding to each cavity 2 2 1 of the nozzle plate 2 2 is provided with a nozzle. (Hole) 2 2 3 is formed.

A pair of electrodes 224 is provided on one surface and the other surface of each piezoelectric element 200, respectively. That is, for one piezoelectric element 200, four electrodes Poles 2 2 4 are joined. By applying a predetermined drive voltage waveform between predetermined electrodes of these electrodes 222, the piezoelectric element 200 is deformed in shear mode and vibrates (indicated by an arrow in FIG. 45). The volume of the cavity 222 (pressure in the cavity) changes, and the ink (liquid) filled in the cavity 222 is ejected from the nozzle 222 as droplets. That is, in the inkjet head 100B, the piezoelectric element 200 itself functions as a diaphragm.

In the same manner as described above, the ink jet head 100 C shown in FIG. 46 is also one in which the ink (liquid) in the cavity 23 is ejected from the nozzle 23 1 by driving the piezoelectric element 200. The inkjet head 100C includes a nozzle plate 230 on which the nozzles 23 are formed, a spacer 232, and a piezoelectric element 200. The piezoelectric element 200 is installed at a predetermined distance from the nozzle plate 230 through a spacer 23, and the nozzle plate 230, the piezoelectric element 200, and the spacer 23 The cavity 2 3 3 is formed in the space surrounded by 2.

A plurality of electrodes are joined to the upper surface of the piezoelectric element 200 in FIG. That is, a first electrode 234 is joined to a substantially central portion of the piezoelectric element 200, and second electrodes 235 are joined to both sides thereof. By applying a predetermined drive voltage waveform between the first electrode 234 and the second electrode 235, the piezoelectric element 200 deforms in the shear mode and vibrates (indicated by an arrow in FIG. 46). Due to this vibration, the volume of the cavity 23 3 (pressure in the cavity) changes, and the ink (liquid) filled in the cavity 2 33 is discharged as droplets from the nozzle 2 31. That is, in the ink jet head 100 C, the piezoelectric element 200 itself functions as a diaphragm.

In the same manner as described above, the ink-jet head 100D shown in FIG. 47 also drives the piezoelectric element 200 so that the ink (liquid) in the cavity 2450 flows from the nozzle 2401. It discharges. This inkjet head 100D is formed by laminating a nozzle plate 240 on which nozzles 241 are formed, a capity plate 242, a diaphragm 243, and a plurality of piezoelectric elements 200. And a multi-layer piezoelectric element 201.

The cavity plate 242 is formed into a predetermined shape (a shape that forms a concave portion), whereby the cavity 245 and the reservoir 246 are formed. The cavities 245 and the reservoir 246 communicate with each other via an ink supply port 247. In addition, the reservoir 246 communicates with the ink cartridge 31 via the ink supply tube 311.

The middle and lower ends of the multilayer piezoelectric element 201 in FIG. 47 are joined to the diaphragm 243 via the intermediate layer 244. A plurality of external electrodes 248 and internal electrodes 249 are joined to the laminated piezoelectric element 201. That is, an external electrode 248 is joined to the outer surface of the multilayer piezoelectric element 201, and between the piezoelectric elements 200 constituting the multilayer piezoelectric element 201 (or inside each piezoelectric element). Has an internal electrode 2 49. In this case, the external electrodes 248 and a part of the internal electrodes 249 are alternately arranged so as to overlap in the thickness direction of the piezoelectric element 200.

Then, by applying a driving voltage waveform from the head driver 33 between the external electrode 2 48 and the internal electrode 2 49, the multilayer piezoelectric element 201 becomes as shown by the arrow in FIG. 48. It deforms (expands and contracts in the vertical direction in Fig. 47) and vibrates, and the vibration vibrates the diaphragm 243. Due to the vibration of the vibration plate 243, the volume of the cavity 245 (pressure in the cavity) changes, and the ink (liquid) filled in the cavity 245 is discharged as droplets from the nozzle 241.

The liquid amount reduced in the cavity 245 due to the ejection of the droplet is supplied from the reservoir 246 by supplying ink. Ink is supplied to the reservoir 2 4 6 from the ink cartridge 3-1 via the ink supply tube 3 1 1. In the case of the ink jet head 100 A to 100 D having the above-described piezoelectric element, similarly to the above-described capacitive ink jet head 100, as a diaphragm or a diaphragm, Based on the residual vibration of the functioning piezoelectric element, it is possible to detect an abnormality in droplet ejection or to specify the cause of the abnormality. In the inkjet heads 100B and 100C, a diaphragm (a diaphragm for detecting residual vibration) as a sensor is provided at a position facing the cavity to detect residual vibration of the diaphragm. It can also be configured.

Next, another configuration example of the inkjet head according to the present invention will be described. FIG. 48 is a perspective view showing the configuration of the head unit 100 H, and FIG. 49 is a schematic diagram corresponding to one color ink (one cavity) of the head unit 100 H shown in FIG. It is sectional drawing. Hereinafter, description will be made based on these drawings, but the description will be focused on the points different from the first embodiment described above, and description of the same matters will be omitted.

The head unit 100 H shown in these figures is based on a so-called film boiling ink jet system (thermal jet system), and includes a support plate 410, a substrate 420, an outer wall 430 and a partition wall 404. 31 and the top plate 44 are joined in this order from the lower center in FIGS. 48 and 49.

The substrate 420 and the top plate 44 are installed at a predetermined interval through the outer wall 43 and a plurality of (six in the illustrated example) partition walls 431 arranged in parallel at equal intervals. Has been done. A plurality of (5 in the example shown) cavities (pressure chambers: ink chambers) 4 3 2 partitioned by partition walls 4 3 1 are provided between the substrate 4 20 and the top plate 4 4 0. Is formed. Each cavity 4 32 is in the shape of a strip (a rectangular parallelepiped).

Also, as shown in FIGS. 48 and 49, each cavity 4 32 in FIG. The side end (upper middle in Fig. 48) is covered by the nozzle plate (front plate) 4 33. A nozzle (hole) 4334 communicating with each cavity 4332 is formed in the nozzle plate 433, and ink (liquid material) is discharged from the nozzle 4334.

In FIG. 48, the nozzles 4334 are arranged linearly, that is, in a row, with respect to the nozzle plate 433, but it goes without saying that the arrangement pattern of the nozzles is not limited to this. The pitch of the nozzles 43 arranged in a row can be appropriately set according to the printing accuracy (d p i) and the like.

The nozzle plate 4 33 is not provided, and the upper end (left end in FIG. 49) of each cavity 4 32 in FIG. 48 is open. Good.

In addition, an ink intake port 41 is formed in the top plate 44, and the ink intake port is connected to the ink cartridge 31 via an ink supply tube 311. Although not shown, a damper chamber (having a rubber damper, the capacity of which changes due to its deformation) may be provided between the ink intake port 44 1 and the ink cartridge 31. As a result, the damper chamber absorbs a change in the ink swing pressure when the carriage 32 reciprocates, and a predetermined amount of ink can be stably supplied to the head unit 100H. .

Support plate 4 10, outer wall 4 3 0, partition 4 3 1, top plate 4 4 0 and nozzle plate

4 3 3 are various metal materials such as stainless steel and various resin materials, respectively.

It is composed of various ceramics. Further, the substrate 420 is made of, for example, a silicon or the like.

Heating elements 450 are respectively installed (buried) at locations corresponding to the cavities 432 on the substrate 420. Each of the heating elements 450 is separately energized by a head driver (conductive means) 452 to generate heat. Head dry The bus 452 outputs, for example, a pulse signal as a drive signal of the heating element 450 in accordance with a print signal (print data) input from the control unit 6.

The surface of the heating element 450 on the side of the cavity 43 is covered with a protective film (anti-cavity film) 451. The protective film 451 is provided to prevent the heating element 450 from directly contacting the ink in the cavity 432. By providing the protective film 451, it is possible to prevent the heating element 450 from being deteriorated or deteriorated due to contact with the ink.

In the vicinity of each heating element 450 of the substrate 420, and corresponding to each cavity 432, a recessed portion 450 is formed. The concave portion 450 can be formed by, for example, a method such as etching or punching. The diaphragm 461 is installed so as to shield the cavity 432 side of the concave portion 4600. This diaphragm 461 elastically deforms (elastically displaces) in the vertical direction in FIG. 49 following changes in pressure (fluid pressure) in the cavity 432.

The constituent material and thickness of diaphragm 461 are not particularly limited, and are appropriately set. On the other hand, the other side of the concave portion 460 is covered with a support plate 410, and a portion of the support plate 410 corresponding to each diaphragm 461 on the upper surface in FIG. Each is provided with a segment electrode 462.

Diaphragm 461 and segment electrode 462 are arranged substantially in parallel with a predetermined gap distance. The gap distance (gap length g) between the diaphragm 461 and the segment electrode 462 is not particularly limited, and is appropriately set. By arranging diaphragm 461 and segment electrode 462 at a slight distance, a parallel plate capacitor can be formed. Then, as described above, when the diaphragm 461 elastically deforms in the vertical direction in FIG. 49 following the pressure in the cavity 43, the diaphragm 46 1 and the segment electrodes 4 62 The gap distance changes, and the capacitance C of the parallel plate capacitor changes. This change in capacitance C is conducted to diaphragm 46 1 and segment electrode 4 62 respectively. It appears as a change in the voltage difference between the common electrode 470 and the external segment electrode 471, and as described above, by detecting this, the residual vibration (damped vibration) of the diaphragm 461 is known. be able to.

Outside the cavity 432 of the substrate 420, a common electrode 470 is formed. An external segment electrode 471 is formed outside the cavity 432 of the support plate 4110.

The constituent materials of the segment electrode 462, the common electrode 470, and the external segment electrode 471 include, for example, stainless steel, aluminum, gold, a body, and alloys containing these. Further, the segment electrode 462, the common electrode 470, and the external segment electrode 471 can be formed by, for example, a method such as bonding of metal foil, plating, vapor deposition, or sputtering.

Each diaphragm 4 6 1 and the common electrode 4 7 0 are electrically connected by a conductor 4 7 5, and each segment electrode 4 6 2 and each external segment electrode 4 7 1 are electrically connected by a conductor 4 7 6 Connected.

The conductors 475 and 476 are respectively: (1) a conductor such as a metal wire is provided; (2) a conductive material such as gold or copper on the surface of the substrate 420 or the support plate 410; And (3) those obtained by imparting conductivity by applying ion doping or the like to a conductor forming portion of the substrate 420 or the like.

A plurality of the head units 100H as described above can be arranged so as to overlap (in other stages) in the vertical direction in FIG. FIG. 50 shows an example of the arrangement of the nozzles 4 3 4 when four colors of ink (ink force.—tridge 3 1) are applied. It is possible to adopt a configuration in which one nozzle plate 433 is joined to the front surface thereof and one nozzle plate 433 is joined thereto.

The arrangement pattern of the nozzles 4 3 4 on the nozzle plate 4 3 3 is not particularly limited, but as shown in FIG. 3 4 can be arranged so as to be shifted by a half pitch.

Next, the operation (operation principle) of the head unit 100H will be described. When a driving signal (pulse signal) is output from the head driver 33 and the heating element 450 is energized, the heating element 450 instantaneously generates heat to a temperature of 300 ° C. or more. As a result, bubbles due to film boiling (different from bubbles that enter and cause a non-ejection-causing cavity described later) 480 are generated on the protective film 451, and the bubbles 480 are instantaneously generated. Swell. As a result, the liquid pressure of the ink (liquid material) filled in the cavity 432 increases, and a part of the ink is ejected from the nozzle 434 as a liquid droplet.

Immediately after the ink droplet is ejected, the bubble 480 rapidly contracts and returns to its original state. At this time, the diaphragm 461 is elastically deformed by the pressure change in the cavity 432, and attenuated vibration (residual vibration) occurs until the next drive signal is input and the ink droplet is ejected again. .

When the vibration plate 461 generates a damped vibration, the capacitance between the vibration plate 461 and the segment electrode 462 opposed thereto changes accordingly. This change in capacitance appears as a change in the voltage difference between the common electrode 470 and the external segment electrode 471, and by reading this, the non-ejection of ink droplets or its cause is detected and specified. be able to. That is, the state (pattern) of the voltage difference (change in capacitance) between the common electrode 470 and the external segment electrode 471 when ink droplets are normally ejected from the nozzle 434 is compared. This makes it possible to determine whether or not the ink droplet has been ejected normally, and to compare and identify the state (pattern) of each cause of the non-ejection of the ink droplet to determine whether the ink droplet has been ejected properly. The cause of the ejection can be determined.

The amount of liquid reduced in the cavity 4 32 due to the ejection of ink droplets is replenished by supplying new ink into the cavity 4 32 from the ink inlet 4 4 1. This ink is supplied from the ink cartridge 3 1 to the ink supply tube 3 1 1 Supplied through.

As described above, the droplet discharge device of the present invention has been described based on the illustrated embodiments. However, the present invention is not limited to this, and each part constituting the droplet discharge head or the droplet discharge device is However, it can be replaced with any configuration that can exhibit the same function. Further, other arbitrary components may be added to the droplet discharge device of the present invention.

The liquid to be discharged (droplets) discharged from the droplet discharge head (the ink jet head 100 in the above-described embodiment) of the droplet discharge device of the present invention is not particularly limited. (Including suspensions, dispersions of emulsions and the like). Ink containing the filter material of the color filter, light emitting material for forming an EL light emitting layer in an organic EL (Electro Luminescence) device, and fluorescent light for forming a phosphor on an electrode in an electron emitting device. Material, Fluorescent material for forming phosphor in PDP (Plasma Dispray Panel), Electrophoretic material for forming electrophoretic material in electrophoretic display device, Forming bank on surface of substrate W Materials to form electrodes, liquid electrode materials to form electrodes, particle materials to form a spacer to form a small cell gap between two substrates, and metal wiring Liquid metal materials, lens materials for forming microlenses, resist materials, and light diffusing materials for forming light diffusers.

Further, the present invention can be applied to any type (form) of a droplet discharge device including a plurality of droplet discharge heads having a diaphragm.

Claims

The scope of the claims

1. A drive that is driven by a drive circuit, and a diaphragm that is displaced by the drive of the drive, the drive circuit drives the drive, and the liquid in the cavity is converted into liquid droplets from a nozzle. A droplet discharging apparatus including a plurality of droplet discharging heads for discharging,

2. The ejection abnormality detection / recovery processing determining means, based on the vibration pattern of the residual vibration of the diaphragm when the actuator is driven to such an extent that the drive circuit does not eject droplets, discharges the droplet. 2. The droplet discharge device according to claim 1, wherein the droplet discharge device detects a head discharge abnormality and determines a recovery process for eliminating the discharge abnormality.

3. The ejection failure detection and recovery processing determining means has a function of detecting a cause of the ejection failure of the droplet ejection head based on a vibration pattern of residual vibration of the diaphragm. Item 2. The droplet discharge device according to item 1.

4. The ejection abnormality detection / recovery processing determining means, when an ejection abnormality of the droplet ejection head is detected, notifies the droplet ejection head of the cause of the ejection abnormality according to the cause of the ejection abnormality. Claims that determine recovery processing to be eliminated Item 3. The droplet discharge device according to Item 3.

5. The recovery means includes: a wiping means for performing a wiping process on a nozzle surface on which nozzles of the droplet discharge head are arranged by a wiper; and driving the actuator to drive the droplets from the nozzles of the droplet discharge head. 2. The liquid according to claim 1, comprising: a flushing unit that performs a flushing process for preliminary discharging the liquid; and a pumping unit that performs a pump suction process using a pump connected to a cap that covers a nozzle surface of the droplet discharge head. Drop ejection device.

6. The ejection abnormality detection / recovery processing determining means, when determining that the cause of the ejection abnormality of the droplet ejection head is the incorporation of bubbles into the cavity, as recovery processing for eliminating the ejection abnormality, The droplet discharge device according to claim 5, wherein the pump suction process is selected.

7. The ejection abnormality detection / recovery processing determining step, when it is determined that the cause of the ejection abnormality of the droplet ejection head is that the paper dust is attached near the outlet of the nozzle, eliminates the ejection abnormality. 6. The droplet discharge device according to claim 5, wherein at least the wiping process is selected as the recovery process.

8. If the ejection abnormality detection / recovery processing determining means determines that the cause of the ejection abnormality of the droplet ejection head is that the liquid near the nozzle is thickened by drying, the ejection abnormality is eliminated. 6. The droplet discharge device according to claim 5, wherein the flushing process or the pump suction process is selected as the recovery process.

9. The ejection abnormality detection / recovery processing determining means is configured to eject the droplet ejection head. The liquid according to claim 5, wherein, when it is determined that the cause of the abnormality is that the liquid in the vicinity of the nozzle has increased in viscosity due to drying, the flushing process is selected as a recovery process for eliminating the ejection abnormality. Drop ejection device.

10. The discharge abnormality detection / recovery processing determining means, if the discharge abnormality is not resolved even after performing the flushing processing by the flushing means a predetermined number of times, the pump suction processing as recovery processing for eliminating the discharge abnormality. 10. The droplet discharge device according to claim 9, wherein the device is selected.

11. The droplet discharge device according to claim 5, further comprising an informing means for informing, when the pumping abnormality is not eliminated even after performing the pump suction processing by the pumping means a predetermined number of times, the information.

12. The droplet discharge device according to claim 1, wherein the vibration pattern of the residual vibration of the vibration plate includes a cycle of the residual vibration.

13. When the cycle of the residual vibration of the vibration plate is shorter than a predetermined range, the ejection abnormality detection / recovery processing determining means determines that air bubbles have entered the cavity, and When the period of the residual vibration is longer than a predetermined threshold, it is determined that the liquid near the nozzle has increased in viscosity due to drying, and the period of the residual vibration of the diaphragm is longer than the period in the predetermined range; 13. The droplet discharge device according to claim 12, wherein when the length is shorter than a predetermined threshold value, it is determined that paper dust has adhered near the outlet of the nozzle.

14. The ejection abnormality detection / recovery processing determining means includes an oscillation circuit, and the oscillation circuit generates an oscillation based on a capacitance component that changes due to residual vibration of the vibration plate. 2. The droplet discharging device according to claim 1, wherein the droplet discharging device shakes.

15. The discharge abnormality detection / recovery processing determining means includes an oscillation circuit, and the oscillation circuit oscillates based on the capacitance component of the actuator that changes due to residual vibration of the vibration plate. 2. The droplet discharge device according to item 1, wherein

16. The oscillation circuit according to claim 15, wherein the oscillation circuit constitutes a CR oscillation circuit including a capacitance component of the actuator and a resistance component of a resistance element connected to the actuator. 5. The droplet discharge device according to 4.

17. The discharge abnormality detection / recovery processing determining means generates a voltage waveform of residual vibration of the diaphragm by a predetermined signal group generated based on a change in oscillation frequency in an output signal of the oscillation circuit. 16. The droplet discharging device according to claim 15, including a conversion circuit.

18. The discharge abnormality detection / recovery process determining means includes a waveform shaping circuit for shaping a voltage waveform of residual vibration of the diaphragm generated by the FZV conversion circuit into a predetermined waveform. 17. The droplet discharge device according to item 7.

19. The waveform shaping circuit includes: a DC component removing unit that removes a DC component from a voltage waveform of the residual vibration of the diaphragm generated by the F / V conversion circuit; and a DC component that is removed by the DC component removing unit. 19. The liquid crystal display according to claim 18, further comprising: a comparator for comparing the obtained voltage waveform with a predetermined voltage value, wherein the comparator generates and outputs a rectangular wave based on the voltage comparison. Drop ejection device.

20. The discharge abnormality detection / recovery processing determining means is provided by the waveform shaping circuit. 20. The droplet discharge device according to claim 19, further comprising a measuring means for measuring a period of the residual vibration of the diaphragm from the generated rectangular wave.

21. The measuring means has a counter, and the counter counts the pulse 5 of the reference signal, thereby measuring the time between the rising edge or the rising edge and the falling edge of the rectangular wave. 20. The droplet discharge device according to claim 20 for measuring.

22. The droplet discharge device according to claim 101, wherein the actuating unit is an electrostatic actuating unit.

23. The droplet discharging apparatus according to claim 1, wherein the actuator is a piezoelectric actuator utilizing a piezo effect of a piezoelectric element.

15. The droplet discharge device according to claim 1, wherein the actuator is a film boiling type actuator having a heating element that generates heat when energized.

25. The droplet discharge device according to claim 24, wherein the diaphragm is elastically deformed following a change in pressure in the cavity.

20

26. The storage device according to claim 1, further comprising storage means for storing a cause of the discharge abnormality detected by the discharge abnormality detection / recovery processing determining means in association with a droplet discharge head to be detected. Droplet ejection device.

25 27. The droplet discharge device according to claim 1, wherein the droplet discharge device includes an inkjet printer.