JP2001219581A - Ink-jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a decrease of an ink pressure at a stage of premonitory sign of print inability. SOLUTION: This ink-jet recording apparatus has a nozzle body for applying vibration to the ink jetted from nozzles to generate ink particles, a charging electrode for charging the ink particles, a deflecting electrode for deflecting the charged ink set to an ink supply pump and an ink pressure reducing valve both set to an ink supply passage led from an ink tank to the nozzle body and respectively arranged at the upstream and downstream sides, a pressure sensor for detecting the ink pressure of the ink supply passage, and a control part for controlling to drive the ink supply pump and taking detection signals of the pressure sensor. A bypass passage is set for connecting the upstream side and the downstream side of the ink pressure reducing valve, and a valve means for opening/closing the passage is disposed at the bypass passage. The pressure sensor is set to the downstream side of the bypass passage or of the ink pressure reducing valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle body for generating ink particles by applying vibration to ink ejected from a nozzle, a charging electrode for charging the ink particles, and deflecting the charged ink particles. The present invention relates to an ink jet recording apparatus having a deflection electrode and continuously ejecting ink particles. This type of ink jet recording apparatus is mainly used for printing products produced on a production line.

[0002]

2. Description of the Related Art A conventional ink jet recording apparatus includes a nozzle body for generating ink particles by applying vibration to ink ejected from a nozzle, a charging electrode for charging the ink particles, and deflecting the charged ink particles. A deflecting electrode, an ink supply pump provided in an ink supply passage from the ink tank to the nozzle body, and an ink supply pump disposed upstream and an ink pressure reducing valve disposed downstream, and an ink pressure in the ink supply passage. A pressure sensor that detects
A control unit for controlling the operation of the ink supply pump and taking in the detection signal of the pressure sensor.

[0003]

When the ink pressure in the ink supply flow path is reduced, characters to be printed become large, thereby deteriorating the printing quality, and sometimes the production line is stopped.

[0004] A major cause of the ink pressure drop is a failure or wear of the ink supply pump.

For the detection of the ink pressure, a pressure sensor detects the pressure on the secondary side (downstream side) of the ink pressure reducing valve provided in the ink supply flow path. The measurement of the ink pressure relating to the print quality itself is preferably downstream of the ink pressure reducing valve.

However, the condition of the ink supply pump upstream of the ink pressure reducing valve may be checked by examining the ink pressure after the pressure is reduced by the ink pressure reducing valve. In some cases, printing became impossible.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a device which detects a drop in ink pressure at a precursor stage before printing becomes impossible and can promptly take measures such as repairing an ink supply pump. It is.

[0008]

One of the features of the present invention is that:
A nozzle body for generating ink particles by applying vibration to the ink ejected from the nozzle, a charging electrode for charging the ink particles, a deflection electrode for deflecting the charged ink particles, and an ink tank to the nozzle body. An ink supply pump provided upstream of the ink supply flow path and an ink pressure reducing valve disposed downstream of the ink supply flow path; a pressure sensor for detecting ink pressure in the ink supply flow path; and operation of the ink supply pump. In an ink jet recording apparatus having a control unit for controlling the pressure and taking in a detection signal of a pressure sensor, an ink pressure of an ink supply pump is detected by a pressure sensor without passing through an ink pressure reducing valve.

Thus, the condition of the ink supply pump can be diagnosed at an early stage by detecting the ink pressure that is not reduced by the ink pressure reducing valve, so that a prior response to a failure of the ink supply pump can be taken at an early stage.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

First, a description will be given with reference to FIG.

The ink jet recording apparatus has a main body 1 and a print head 2.

The print head 2 has a nozzle body 3 and a gutter 4. The ink ejected from the nozzles of the nozzle body 3 becomes ink particles 5 by vibration. The gutter 4 collects ink particles not used for printing. Although not shown, a charging electrode for charging the ink particles and a deflection electrode for deflecting the charged ink particles are provided between the nozzle body 3 and the gutter 4.

The main body 1 has a control unit 6 and an ink tank 7. Ink tank 7 stores ink 8. Ink supply channel 10 from ink tank 7 to nozzle body 3
Is provided with an ink supply pump 9, a filter 20, an ink pressure reducing valve 21, a pressure sensor 22, and a supply electromagnetic valve 23 (valve means). The ink flows from the ink tank 7 toward the nozzle body 3, and the ink supply pump 9
The last supply electromagnetic valves 23 are arranged in order from upstream to downstream. The ink supply pump 9 is a pressure type pump called a diaphragm pump or a gear pump.

Of course, the ink pressure reducing valve 21 is disposed downstream of the ink supply pump 9, and the primary side (upstream side) and the downstream side (downstream side) of the ink pressure reducing valve 21 are connected to the bypass flow path 24. It is communicated with. Bypass channel 24
Is provided with a bypass solenoid valve 25 (valve means). When the bypass solenoid valve 25 is opened, ink flows through the bypass flow path 24, and when closed, the ink stops flowing. The pressure sensor 22 is disposed downstream of the ink pressure reducing valve 21. However, when the bypass solenoid valve 25 is opened, the ink pressure on the upstream sum side of the ink pressure reducing valve 21 is detected without passing through the ink pressure reducing valve 21. Will do. Solenoid valve for bypass 2
5 is closed, the pressure sensor 22
It is natural that the ink pressure on the downstream side is detected. If the pressure sensor 22 is on the downstream side of the bypass solenoid valve 25, the same applies to the bypass flow path 24.

A recovery pump 31 is provided in the ink recovery flow path 30 extending from the gutter 4 to the ink tank 7. Ink particles not used for printing that have entered the gutter 4 are sucked by the collection pump 31 and collected in the ink tank 7.

The ink tank 7 is communicated with the ink tank 7 between the ink pressure reducing valve 21 and the solenoid valve 23 in the middle of the ink supply flow path 10 by the cleaning flow path 40. The washing flow path 40 is provided with an electromagnetic valve 41 for washing. When cleaning the ink supply flow path 10, the supply electromagnetic valve 23 is closed, the cleaning electromagnetic valve 41 is opened, and the ink supply pump 9 is operated to clean the inside of the flow path. Washing is performed using ink or an ink solvent, and the washed liquid is collected in the ink tank 7.
When cleaning the entire nozzle body 3, the gutter 4, and the ink recovery flow path 30, the electromagnetic valve 41 for cleaning is closed,
This is performed by opening the supply solenoid valve 23. The liquid after washing is collected in the ink tank 7.

Next, a control circuit diagram of the block will be described with reference to FIG.

The control unit 6 includes a print head main body 2 and a display unit 5.
0, ink supply pump 9, recovery pump 31, pressure sensor 22, supply solenoid valve 23, bypass solenoid valve 2
5. The electromagnetic valve 41 for cleaning is connected via a cable or a lead wire.

The print head body 2, the ink supply pump 9,
The operation control of the recovery pump 31, the supply electromagnetic valve 23, the bypass electromagnetic valve 25, and the cleaning electromagnetic valve 41 is performed by the control unit 6.

The detected value of the pressure sensor 22 is taken into the control section 6 and utilized for the operation of the ink jet recording apparatus. Various display contents including the operation status of the ink jet recording apparatus are displayed on the display unit 50 according to an instruction from the control unit 6.

The above is one embodiment of the present invention mainly from the viewpoint of the configuration. Next, the operation will be described.

The ink supply pump 9 and the recovery pump 31 are operated under the instruction control of the control unit 6. Since the electromagnetic valve 25 for bypass and the electromagnetic valve 41 for cleaning are closed and the electromagnetic valve 23 for supply is open, the supplied ink is ejected from the nozzle of the nozzle body 3 to become ink particles. The ink particles are deflected in the flight direction by a charging electrode and a deflection electrode. Then, the printed material (product) conveyed on the production line is struck on the object (product) to form a print by ink particles. Ink particles not used for printing enter the gutter 4 and return to the ink tank 7 via the ink recovery flow path 30.

During this printing operation, the control section 6 continues to take in the ink pressure detection value of the ink supply passage 10 detected by the pressure sensor 22. When the ink pressure on the downstream side of the ink pressure-reducing valve 21 drops so as not to be suitable for printing, the control unit 6 gives an instruction to stop the printing operation and to display a display to inform the display unit of the stoppage.

Before the printing operation, the condition of the ink supply pump 9, which is the main cause of the ink pressure malfunction, is diagnosed in order to prevent the occurrence of inappropriate printing during the printing operation. This diagnosis can be made after the printing operation is completed or when printing is interrupted.

That is, the solenoid valve 25 for bypass and the solenoid valve 23 for supply are opened, the solenoid valve 41 for cleaning is closed, and the ink supply pump 9 is operated, whereby the pressure sensor 22 is opened.
Detects the ink pressure on the upstream side of the ink pressure reducing valve 21 via the bypass flow path 24. The pressure sensor 22 can detect the ink pressure before the pressure reduction without passing through the ink pressure reducing valve 21 even at the downstream side of the ink pressure reducing valve 21, so that the condition of the ink supply pump 9 can be diagnosed well. It is difficult to diagnose the condition of the ink supply pump 9 on the downstream side of the ink pressure reducing valve 21, and it is easy on the upstream side because the ink pressure on the downstream side of the ink pressure reducing valve 21 becomes a constant pressure due to the pressure reducing action. This is because the fluctuation does not appear on the downstream side. The pressure fluctuation due to the malfunction of the ink supply pump 9 appears on the downstream side only when the pressure on the upstream side drops and falls below the constant pressure value on the downstream side provided by the ink pressure reducing valve 21.

By appropriately examining the ink pressure on the upstream side of the ink pressure reducing valve 21 as described above, any malfunction or failure that has already occurred in the ink supply pump 9 without any trouble in the printing operation can be detected at an early stage. Can be found. Since the repair or adjustment of the ink supply pump 9 can be performed at an early stage, it is possible to prevent a production trouble in which the production line is stopped due to the failure of the ink supply pump.

The pressure detection of the pressure sensor 22 relating to the condition diagnosis of the ink supply pump 9 will be described in further detail with reference to a flowchart shown in FIG.

The rated pressure of the ink supply pump 9 is 0.5 M
It is assumed that Pa (megapascal) and the pressure downstream of the ink pressure reducing valve 21 have a constant value of 0.3 MPa (megapascal).

In step 100, the operation of the ink supply pump 9 is performed. At the same time, in step 101, the solenoid valve 25 for bypass is opened. Next, at step 102, it is checked whether or not the detected pressure value of the pressure sensor 22 is 0.45 MPa or more. When the pressure is 0.45 MPa or more, the display unit 50 is informed that the printing state can be shifted to the printing state, and the display unit 50 is notified that printing is appropriate. The performance of the ink supply pump 9 is such that the pressure is (0.45 to 0.5) MPa,
Downstream pressure constant value of the ink pressure reducing valve 21 (0.3 MPa)
Therefore, it is suitable for printing operation.

If it is determined in step 102 that the pressure is less than 0.45 MPa, it is checked in step 104 whether the detected pressure value of the pressure sensor 22 is 0.3 MPa or more.
If the pressure is 0.3 MPa or more, the output of the alarm is displayed on the display unit 50 in step 105. At the same time, in step 106, a display indicating that printing is appropriate is displayed on the display unit 50 assuming that the printing state can be shifted. The performance of the ink supply pump 9 is 0.3 MPa, which is equal to the constant value of the downstream pressure of the ink pressure reducing valve 21 (0.3 MPa), which is suitable for the printing operation. However, since a warning is given on the display unit 50, it is wise to perform the printing operation in consideration of the warning.

If it is determined in step 104 that the pressure is less than 0.3 MPa, the output of the abnormality is displayed in step 107 on the display unit 5.
Set to 0. At the same time, in step 108, a display is displayed to inform the user that the ink jet recording apparatus has to be stopped and that printing is inappropriate. Since the performance of the ink supply pump 9 is less than 0.3 MPa, the pressure on the downstream side of the ink pressure reducing valve 21 naturally falls below 0.3 MPa, which is not suitable for the printing operation.

If the following measures are added to the above flow chart, the accuracy of the condition diagnosis of the ink supply pump is further improved.

Step 1 for opening the bypass solenoid valve 25
A time learn of about 10 seconds is added between 01 and the step 102 for checking the detected pressure value of the pressure sensor 22.

That is, even if the ink supply pump is hindered in the performance of decreasing the flow rate, the ink pressure rises to the same level as the normal ink supply pump when the operation time is extended. A simple check of the ink pressure may overlook an ink supply pump that has a problem in performance such as a decrease in flow rate, as there is no problem.

Therefore, steps 101 and 102
By checking the pressure detection value of the pressure sensor 22 with an appropriate time interval between them and comparing the pressure detection value with the pressure detection value (reference value) of a normal ink supply pump, such a performance hindrance of the flow rate decrease is hindered. A suitable ink supply pump can be found at an early stage to determine whether printing operation is appropriate.

As described above, the malfunction of the ink supply pump can be more accurately found by considering the pressure detection by the pressure sensor and the time required for the detection.

Next, another embodiment shown in FIG. 2 will be described.

In this embodiment, features that are different from the previous embodiment will be mainly described, and portions common to the previous embodiment will be denoted by the same reference numerals and description thereof will be omitted.

The difference is that a manual valve 200 is provided in place of the bypass solenoid valve 25 provided in the previous embodiment.

Since the valve 2 is of a manual type, there is an inconvenience of having to manually open and close the valve 2. However, there is no need for an electrical connection with the control unit 6 and there is a merit that the cost is advantageous. There is.

Next, another embodiment shown in FIG. 5 will be described.

In this embodiment, features that are different from the first embodiment will be mainly described, and portions common to the first embodiment will be assigned the same reference numerals and description thereof will be omitted.

The bypass solenoid valve 25 provided in the bypass passage 24 shown in the first embodiment is removed, and the passage switching valves (flow passage switching means) 300 are provided upstream and downstream of the ink pressure reducing valve 21 respectively. , 301 are different.

In normal operation of the ink jet recording apparatus, the upstream flow path switching valve 300 and the downstream flow path switching valve 30 are set so as to communicate with the ink pressure reducing valve 21.
The pressure sensor 22 can detect the ink pressure downstream of the ink pressure reducing valve 21.

When checking the condition of the ink supply pump 9, the upstream channel switching valve 300 and the downstream channel switching valve 301 are set so as to communicate with the bypass channel 24. In this case, since the ink pressure reducing valve 21 is completely separated from the ink supply flow path 10 in terms of the flow path, the condition of the ink supply pump 9 is more improved than when the ink pressure reducing valve 21 is in communication. You can find out well.

The flow path switching valve 30 on the downstream side due to cost reduction
When 1 is omitted, a backflow prevention valve or the like is provided downstream of the ink pressure reducing valve 21 to prevent backflow to the ink supply pump 9. A check valve or the like may be provided upstream of the ink pressure reducing valve 21.

Next, another embodiment shown in FIG. 6 will be described.

In this embodiment, features that are different from the first embodiment will be mainly described, and portions common to the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

The pressure sensor 400 is provided upstream of the ink pressure reducing valve 21 by removing the bypass passage 24 shown in the first embodiment. Although the number of pressure sensors increases and the cost increases, there is the advantage that the ink pressure on the upstream side of the ink pressure reducing valve can be detected with a simple flow path configuration without the need for a bypass flow path or an electromagnetic valve.

[0051]

As described above, according to the present invention, it is possible to detect a drop in ink pressure at a precursor stage before printing becomes impossible, so that it is possible to quickly repair the ink supply pump.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an ink circulation path of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an ink circulation path of an ink jet recording apparatus according to another embodiment of the present invention.

FIG. 3 is a block diagram of a control circuit according to an embodiment of the present invention.

FIG. 4 is a flowchart illustrating an operation state according to the embodiment of the present invention.

FIG. 5 is a diagram illustrating an ink circulation path of an ink jet recording apparatus according to another embodiment of the present invention.

FIG. 6 is a diagram illustrating an ink circulation path of an ink jet recording apparatus according to another embodiment of the present invention.

[Explanation of symbols]

2 nozzle body, 7 ink tank, 10 ink supply channel, 9 ink supply pump, 21 ink reducing valve, 2
2. Pressure sensor.

Claims (10)

[Claims] 1. A nozzle body for generating ink particles by applying vibration to ink ejected from a nozzle, a charging electrode for charging the ink particles, a deflecting electrode for deflecting the charged ink particles, and an ink tank. Provided in the ink supply flow path from the to the nozzle body, and an ink supply pump disposed upstream and an ink pressure reducing valve disposed downstream, a pressure sensor for detecting the ink pressure of the ink supply flow path, In an ink jet recording apparatus having a control unit for controlling the operation of an ink supply pump and taking in a detection signal of a pressure sensor, detecting the ink pressure of the ink supply pump with a pressure sensor without passing through an ink pressure reducing valve. Characteristic inkjet recording device. 2. The ink-jet recording apparatus according to claim 1, wherein the determination as to whether or not the printing operation is appropriate is made according to the detection value of the pressure sensor. 3. The ink-jet recording apparatus according to claim 1, wherein the appropriateness of the printing operation is determined in consideration of a detection value of the pressure sensor and an elapsed time until the detection value is reached. . 4. An ink jet recording apparatus according to claim 2, further comprising a display unit for displaying a display in accordance with an instruction from a control unit, and displaying display contents on whether or not the printing operation is appropriate on the display unit. apparatus. 5. A nozzle body for generating ink particles by applying vibration to ink ejected from a nozzle, a charging electrode for charging the ink particles, a deflecting electrode for deflecting the charged ink particles, and an ink tank. An ink supply pump provided at an ink supply flow path from the ink supply passage to the nozzle body, and an ink supply pump disposed upstream and an ink pressure reducing valve disposed downstream, a pressure sensor for detecting ink pressure in the ink supply flow path, and ink A control unit for controlling the operation of a supply pump or taking in a detection signal of a pressure sensor, wherein a flow path for selectively communicating an upstream side and a downstream side of the ink pressure reducing valve with the pressure sensor. An ink jet recording apparatus comprising switching means. 6. A nozzle body for generating ink particles by applying vibration to ink ejected from a nozzle, a charging electrode for charging the ink particles, a deflecting electrode for deflecting the charged ink particles, and an ink tank. An ink supply pump provided at an ink supply flow path from the ink supply passage to the nozzle body, and an ink supply pump disposed upstream and an ink pressure reducing valve disposed downstream, a pressure sensor for detecting ink pressure in the ink supply flow path, and ink An ink jet recording apparatus having a control unit for controlling the operation of a supply pump and taking in a detection signal of a pressure sensor, wherein a bypass flow path communicating between an upstream side and a downstream side of the ink pressure reducing valve is provided; Flow path switching means for switching to the bypass flow path side or the ink pressure reducing valve side on the upstream side of the valve; An ink jet recording apparatus, wherein the pressure sensor is disposed in a path or downstream of the ink pressure reducing valve. 7. An ink jet recording apparatus according to claim 5, wherein the determination as to whether or not the printing operation is appropriate is made according to the detection value of the pressure sensor. 8. An ink jet recording apparatus according to claim 7, wherein the printing operation is judged to be appropriate in consideration of a detection value of the pressure sensor and an elapsed time until the detection value is reached. . 9. An ink jet recording apparatus according to claim 7, further comprising a display unit for displaying a display in accordance with an instruction of a control unit, and displaying on said display unit whether or not said printing operation is appropriate. apparatus. 10. A nozzle body for generating ink particles by applying vibration to ink ejected from a nozzle, a charging electrode for charging the ink particles, a deflecting electrode for deflecting the charged ink particles, and an ink tank. An ink supply pump provided at an ink supply flow path from the ink supply passage to the nozzle body, and an ink supply pump disposed upstream and an ink pressure reducing valve disposed downstream, a pressure sensor for detecting ink pressure in the ink supply flow path, and ink An ink jet recording apparatus having a control unit for controlling the operation of a supply pump and taking in a detection signal of a pressure sensor, wherein a bypass flow path communicating between an upstream side and a downstream side of the ink pressure reducing valve is provided; A valve means for opening and tightening the flow path in the path, wherein the pressure sensor is provided on the downstream side of the bypass flow path or the ink pressure reducing valve. An ink jet recording apparatus comprising: