JP2002154225A - Ink-jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To collect the ink stably and reduce the ink solvent volatile amount in an ink-jet recording device. SOLUTION: Printing existence or absence information for ink particles is produced by printing data. From the printing existence or absence information, the number of ink particles n flowing into a gutter 11 in time Δt is provided. From the number of ink particles n, the gutter flow amount Q flowing into the gutter 11 is calculated. Since the number of ink particles n per time Δt varies depending on change of the printing content, the gutter flow amount Q is provided per Δt continuously. According to the calculated gutter flow amount Q, the rotational frequency R of a collecting pump 14 is controlled so as to generate a large negative pressure in the gutter 1 in the case the gutter flow amount is large, and generate a small negative pressure in the gutter 11 in the case the gutter flow amount is small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for ejecting ink particles from a nozzle and controlling the flight trajectory of the ink particles for printing, and a control method therefor.
In particular, the present invention relates to an ink jet recording apparatus and a method for controlling the ink jet recording apparatus in consideration of a reduction in a solvent volatilization amount of the ink.

[0002]

2. Description of the Related Art In an ink jet recording apparatus which performs printing by controlling the flight trajectory of ink particles, ink particles not used for printing are collected through an ink collecting path and reused. This ink recovery path is generally disclosed in
As described in JP-A-09-09657, a gutter configured to receive ink particles not used for printing, a collection pump connected to the gutter by a tube, and a tube connecting the collection pump and the ink container are provided. Have been.
Then, the flight trajectory of the ink particles not used for printing is controlled so as to head toward the gutter. After the ink particles collide with the gutter, the ink particles are collected into the ink container together with air by the negative pressure of the collection pump. When the ink is collected from the gutter, the air is taken into the ink collection path together with the ink, so that the solvent component of the ink evaporates into the air in the ink collection path. The air containing the solvent content of the ink reaches the ink container and is then released from the ink container to the atmosphere. As a result, the physical properties of the ink deteriorate, the environment is adversely affected, and the running cost for replenishing the volatilized solvent increases.

In order to cope with the above situation and to reduce the evaporation of the solvent in the ink, Japanese Patent Application Laid-Open No. 2000-094657 discloses a method of measuring the amount of air exhausted from a recovery pump, and recovering the ink from the amount of air. There is disclosed a technique for estimating a state and controlling the operation of the recovery pump so that the number of rotations of the recovery pump is minimized.

[0004]

In the prior art disclosed in the above publication, pump control is performed by estimating the state of ink recovery from the amount of air exhausted from the recovery pump. However, when there is a distance from the gutter to the collection pump, the collection state estimated from the exhaust volume is different from the actual collection state in which the amount of ink particles flowing into the gutter (gutter flow rate) changes depending on the print content. Due to the time required for the ink flow to the pump, a delay is created, which makes the negative pressure in the gutter formed by the collecting pump controlled based on the collecting state estimated from the displacement amount inadequate. Therefore, if the negative pressure is larger than necessary, the amount of air sucked from the gutter simultaneously with the ink increases, and there is a problem in that the solvent evaporation amount of the ink increases. In addition, there is a problem that the ink cannot be collected if the negative pressure is small.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to stably recover ink in an ink-jet recording apparatus and reduce the amount of solvent volatilized by ink.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a particle generator for generating ink particles by ejecting ink from a nozzle, and generating a recording signal based on print data. A print control unit that charges the ink particles based on a recording signal, and controls a flight path of the charged ink particles so that a flight direction of the ink particles not used for printing is different from a flight direction of the ink particles used for printing. In an ink jet recording apparatus comprising: a direction control unit for directing a direction, and an ink recovery unit for recovering ink particles not used for printing, the ink recovery unit includes an ink particle for receiving ink particles not used for printing. Receiving means, and ink particle suction means connected to the ink particle receiving means for sucking ink particles, the ink particle suction means comprising: , Characterized in that it is configured to vary the suction force according to the amount of the ink particles not used for the printing.

[0007] The above object is also achieved by a particle forming section for ejecting ink from a nozzle to generate ink particles, and a print control for generating a recording signal based on print data and charging the ink particles based on the recording signal. Unit, direction control means for controlling the flight path of the charged ink particles, and for directing the flight direction of the ink particles not used for printing to a direction different from the flight direction of the ink particles used for printing, and ink not used for printing. An ink collection unit that collects particles, and an ink jet recording apparatus that includes the ink collection unit, an ink particle reception unit that receives ink particles not used for the printing, and an ink particle reception unit that is connected to the ink particle reception unit; An ink particle suction means for generating a negative pressure in the ink particle receiving means and sucking the ink particles. The also achieved by configuring to vary the negative pressure generated according to the amount of the ink particles not used for the printing.

In order to calculate the amount of ink particles not used for the printing, the print control unit includes a recording signal generating unit for generating a recording signal of each ink particle and printing presence / absence information based on print data; The amount of ink particles not used for printing is continuously calculated based on the presence / absence information, and a signal indicating a value of a suction force or a negative pressure to be generated by the ink particle suction means is continuously generated based on the calculated amount. The ink particle suction means may be configured to change the suction force or the negative pressure by using the output of the flow rate calculation means as an input.

When the amount of ink particles not used for printing per hour is small, the flow rate calculating means sets the value of the suction force or negative pressure to be generated by the ink particle suction means to a small value and uses the value for printing. When the amount of ink particles not to be removed per unit time is large, the value of the suction force or the negative pressure to be generated by the ink particle suction means is increased.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. First, a schematic configuration of the ink jet recording apparatus will be described with reference to FIG. The illustrated ink jet recording apparatus includes a nozzle 6 that is a particle generator that regularly generates ink particles 8 by vibrating the ink 16, an ink supply path 21 that supplies ink to the nozzle 6, and a nozzle 6 that generates ink. A charging electrode 7 forming a part of a printing controller for charging the charged ink particles, an upper deflecting electrode 9 and a lower deflecting electrode 10 as direction control means for controlling a flight trajectory of the charged ink particles, and an ink collecting unit. And an ink recovery path 22.

The ink supply path 21 includes an ink container 1 for storing the ink 16, a supply pump 2 for pressure-feeding the ink 16 from the ink container 1, and a regulator connected to the discharge side of the supply pump 2 for adjusting the ink pressure. Including a pressure valve 3, a solenoid valve 4 connected to the outlet side of the pressure regulating valve 3 to open and close the ink flow path, a filter 5 connected to the outlet side of the solenoid valve 4, and a tube connecting these in order. And supplies the ink 16 to the nozzle 6. Nozzle 6 is an excitation source (not shown)
The ink particles 8 are regularly generated by vibrating the ink 16. In the present embodiment, the nozzle 6 is driven at 68 kHz.

A recording signal source (not shown) is connected to the charging electrode 7.
Is connected, and the ink particles 8 are charged by applying a predetermined recording signal voltage to the charging electrode 7. At this time, the ink particles not used for printing are charged to a state different from the ink particles used for printing.

The upper deflecting electrode 9 and the lower deflecting electrode 10 are arranged to face each other, and the charged ink particles 8 are introduced therebetween. A high voltage is applied to the upper deflection electrode 9 and the lower deflection electrode 10
Is grounded, so that an electrostatic field is formed between the upper deflection electrode 9 and the lower deflection electrode 10. The charged ink particles 8 introduced between the upper deflecting electrode 9 and the lower deflecting electrode 10 are deflected in flight trajectory in accordance with the amount of charge, and printing is performed. Since the ink particles not used for printing are charged in a different state from the ink particles used for printing, the flight trajectory is controlled to fly in a different direction from the ink particles used for printing.

The ink recovery path 22 includes a play 11 serving as an ink particle receiving means for receiving the ink particles 8 not used for recording (printing), a solenoid valve 15 connected to the ink outlet side of the gutter 11, and a solenoid valve 15. Filter 12 on the exit side of
The recovery pump 14 is connected to the suction side via a variably rotating speed, and a tube is connected to the recovery pump 14 in order. The recovery pump 14 is configured to generate a negative pressure in the gutter 11 via the electromagnetic valve 15 and the filter 12, and the discharge side thereof is connected to the ink container 16. The ink particles 8 not used for recording pass between the upper deflecting electrode 9 and the lower deflecting electrode 10 to form a gutter 11.
And is collected together with air from the gutter 11 by the negative pressure generated by the collection pump 14, returned to the ink container 1, and reused. The air collected together with the ink is discharged from the ink container 1 to the outside.

Next, a control circuit which is a main part of the print control unit of the ink jet recording apparatus according to the embodiment will be described with reference to FIG. The control circuit includes a CPU 300 and a CPU
A bus line 370 connected to the bus line 300;
70, a RAM 310, a ROM 320, an interface circuit 330, and an interface circuit 33.
0, the pump control circuit 340 and the valve control circuit 35
0, a recording signal source 360 which is a recording signal generating means, an excitation source 380, and an input device 390. The charging electrode 7 is connected to the recording signal source 360, and the excitation source 38
0 is connected to the nozzle 6. The solenoid valves 4 and 15 are connected to a valve control circuit 350, and a pump control circuit 340
, A supply pump 2 and a recovery pump 14 are connected.

The CPU 300 is a central processing unit that controls the inkjet recording apparatus according to the present embodiment.
Also serves as flow rate calculation means. The ROM 320 is a CPU 3
00 is a read-only memory for storing programs and control data necessary for operation. RAM 310 is
This is a rewritable memory that temporarily stores data and the like handled by the CPU 300 during the execution of the program.

The bus line 370 is a signal line for transmitting all data, address signals, and control signals from the CPU 300. The interface circuit 330 mediates input and output of data, address signals, control signals, and the like.

The pump control circuit 340 controls the rotation of the supply pump 2 and the recovery pump 14 based on an instruction from the CPU 300, and constitutes an ink suction means together with the recovery pump 14. The valve control circuit 350 includes the CPU 300
Control of opening and closing of the solenoid valves 4 and 15 based on the command from

An input device 390 inputs print data and operation contents to the device. The excitation source 380 generates an excitation signal based on the input nozzle operating conditions, drives the nozzle 6, and generates ink particles 8. The recording signal source 360 creates a recording signal of each ink particle and printing presence / absence information based on the input printing data, and saves it in the RAM 310.
A recording signal is applied to the charging electrode 7 based on a command from U300.

Next, a method of driving the recovery pump 14 will be described with reference to FIG. First, the relationship between the printing presence / absence information and the ink particle generation timing will be described with reference to FIG. The horizontal axis represents time, and the vertical axis represents the presence or absence of printing. 〇 mark 30 on the horizontal axis
a, 30b,... indicate the timing at which the ink particles 8 are generated. The fact that the printing presence / absence information indicated by the vertical solid line extends to a high position indicates that the ink particles generated at that timing are used for printing, and the printing presence / absence information indicated by a solid line to the intermediate position is at that timing. The generated ink particles indicate that they are not used for printing. For example,
The ink particles generated at the generation timing 30 a are controlled so as not to fly to the print medium and collected by the gutter 11 because the print presence / absence information 31 is short and indicates no printing. The ink particles generated at the generation timing 30b are controlled to fly to the print medium because the print presence / absence information 32 is long and indicate that printing is performed, and are not collected by the gutter 11.

In step 110, the CPU 300, as a flow rate calculating means, continuously obtains the number n of ink particles flowing into the gutter 11 within the time Δt (for example, about 1 second) after the start of printing for each time Δt. . Here, the number n of ink particles flowing into the gutter 11 within the time Δt can be obtained from the non-printing information in the printing presence / absence information stored in the RAM 310. Since the number n of ink particles changes due to a change in the print content, the number n of ink particles flowing into the gutter 11 is determined by the time Δt.
Required every time. In the present embodiment, Δt is fixed, but Δt may be changed according to a change in environmental conditions.

In step 120, the CPU 300
Thus, the ink flow rate (gutter flow rate Q) in the gutter 11 for each time Δt is calculated. Since the volume V of one ink particle 8 is constant, the gutter flow rate Q per time Δt is given by Q =
Calculated as nV / Δt and stored in RAM 310.

In step 130, the CPU 300 operating as the flow rate calculating means determines the rotational speed R of the recovery pump 14 corresponding to the gutter flow rate Q determined in step 120. The relationship between the gutter flow rate Q and the number of revolutions R of the recovery pump 14 for generating a negative pressure appropriate for sucking the ink particles having the flow rate Q from the gutter 11 is determined by an experiment, and the relationship as shown in FIG. R expressed as a relational expression
This was stored in the OM 320 and used. The appropriate negative pressure is a negative pressure that minimizes the amount of sucked air when the ink particles flowing into the gutter 11 are sucked together with the air. Although FIG. 5 shows a straight line, this is merely an example, and is not limited to a straight line but may be a curved line. In any case, when the amount of ink particles flowing into the gutter 11 is small, the negative pressure generated in the gutter 11 is reduced, and when the amount of ink particles flowing into the gutter 11 is large, the negative pressure generated in the gutter 11 is increased. Then, the rotation speed R of the recovery pump 14 is set.

In step 140, the rotation speed R calculated in step 130 is output to the pump control circuit 340, and the pump control circuit 340 sets the rotation speed of the recovery pump 14 to the input rotation speed R and operates. .

By repeating steps 110 to 140 at every Δt as described above, the recovery pump 14 is driven at a rotation speed corresponding to a change in the gutter flow rate.

As described above, based on the printing presence / absence information stored in the RAM 310, the gutter flow rate Q
Is calculated, and the recovery pump 14 is driven at a rotational speed that generates an appropriate negative pressure in the gutter 11 with respect to the calculated gutter flow rate Q for each time Δt. Therefore, the amount of air flowing into the ink recovery path together with the ink. Is reduced. As a result of reducing the amount of air flowing into the ink recovery path, the amount of air released from the ink container 1 to the outside is reduced, and the amount of solvent volatilized to the outside discharged together with the air is reduced. Further, since the amount of air flowing into the ink recovery path together with the ink is reduced, the flow of ink in the path is stabilized, and stable ink recovery is performed.

In consideration of the delay in response to the control of the recovery pump 14, the printing presence / absence information stored in the RAM 310 is read in advance, and the occurrence timing of the change in the gutter flow rate Q and the negative pressure in the gutter 11 by the recovery pump 14 are determined. Can be made to coincide with each other.

In the present embodiment, an example has been described in which the number of revolutions of the recovery pump 14 is controlled to adjust the negative pressure generated in the gutter 11, but if the negative pressure of the gutter 11 can be adjusted, for example, The present invention can also be implemented by ON / OFF control of the electromagnetic valve 15 provided in the ink recovery path 22. For example, the relationship between the gutter flow rate Q and the proportion of the time during which the solenoid valve 15 is open during the time Δt required to generate a negative pressure appropriate for recovering the gutter flow rate Q is determined in advance.
The relationship between the two may be set by confirming through experiments or the like, and the opening and closing of the solenoid valve 15 may be controlled according to the calculated gutter flow rate Q for each time Δt. Since the solenoid valve 15 can be opened and closed in units of 10 milliseconds, a method such as changing the number of times of opening during the time Δt is also possible.

[0029]

As described above, according to the present invention, the rotation speed of the recovery pump is controlled in accordance with the gutter flow rate, and the suction of air from the gutter is reduced by changing the gutter negative pressure by the rotation speed control. can do. As a result, it is possible to realize an ink jet recording apparatus that can stably collect ink and reduce the amount of solvent evaporated.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of a control flow of a recovery pump according to the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of an inkjet recording apparatus according to an embodiment of the invention.

FIG. 3 is a block diagram showing a main configuration of a control circuit in the embodiment shown in FIG. 2;

FIG. 4 is a conceptual diagram showing a relationship between printing presence / absence information and ink particle generation timing in the present invention.

FIG. 5 is a conceptual diagram showing an example of a relationship between a gutter flow rate Q and a rotation speed R of a recovery pump in the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 ink container 2 supply pump 3 pressure regulating valve 4 electromagnetic valve 5 filter 6 nozzle 7 charging electrode 8 ink particle 9 upper deflection electrode 10 lower deflection electrode 11 gutter 12 filter 14 recovery pump 15 electromagnetic valve 16 ink 21 ink supply path 22 ink recovery path

Claims (5)

[Claims] An ink ejection unit configured to eject ink from a nozzle to generate ink particles, a print control unit that generates a recording signal based on print data, and charges the ink particles based on the recording signal. Direction control means for controlling the flight path of the charged ink particles to direct the flight direction of the ink particles not used for printing to a direction different from the flight direction of the ink particles used for printing, and recovering the ink particles not used for printing And an ink collecting unit, the ink collecting unit comprising: an ink particle receiving unit that receives ink particles not used in the printing; and an ink particle receiving unit that is connected to the ink particle receiving unit to form the ink particles. Ink droplet suction means for sucking, the ink particle suction means, the ink particle suction means according to the amount of ink particles not used for the printing, An ink jet recording apparatus configured to change a suction force. 2. A particle generator for ejecting ink from a nozzle to generate ink particles, a print controller for generating a recording signal based on print data, and charging the ink particles based on the recording signal; Direction control means for controlling the flight path of the charged ink particles to direct the flight direction of the ink particles not used for printing to a direction different from the flight direction of the ink particles used for printing, and recovering the ink particles not used for printing And an ink collecting unit for receiving ink particles not used for the printing, the ink collecting unit being connected to the ink particle receiving unit, and receiving the ink particles. Means for generating a negative pressure in the means for suctioning ink particles. The ink particle suction means is used for the printing. An ink jet recording apparatus configured to change a negative pressure generated according to an amount of unused ink particles. 3. The ink jet recording apparatus according to claim 1, wherein the print control unit is configured to generate a recording signal of each ink particle and printing presence / absence information based on print data, and the printing signal. The amount of ink particles not used for printing is continuously calculated based on the presence / absence information, and a signal indicating a value of a suction force or a negative pressure to be generated by the ink particle suction means is continuously generated based on the calculated amount. An ink jet recording apparatus, comprising: a flow rate calculating means for selectively outputting the output; and wherein the ink particle suction means changes an attraction force or a negative pressure by using an output of the flow rate calculating means as an input. 4. The ink jet recording apparatus according to claim 3, wherein the flow rate calculating means is configured to generate a suction force or a negative pressure to be generated by the ink particle suction means when the amount of ink particles not used for printing per time is small. Is set to a small value, and when the amount of ink particles not used for printing per hour is large, the value of the suction force or the negative pressure to be generated by the ink particle suction means is increased. Inkjet recording apparatus. 5. A particle generator for ejecting ink from a nozzle to generate ink particles, a print controller for generating a recording signal based on print data, and charging the ink particles based on the recording signal. Direction control means for controlling the flight path of the charged ink particles to direct the flight direction of the ink particles not used for printing to a direction different from the flight direction of the ink particles used for printing; An ink collection unit that collects by utilizing pressure, and a method for controlling an ink jet recording apparatus, comprising: determining an amount of ink particles not used for printing continuously in a predetermined time unit; A method for controlling an ink jet recording apparatus, comprising: changing a negative pressure of the ink recovery section according to the amount of particles.