JP2000309111A - Ink jet printer and line ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use all the ink, to enlarge an interval for ink refilling, to make this printer economical, to dispense with a waste ink holding means and to miniaturize the printer. SOLUTION: A viscosity of ink in an ink cartridge 102 is estimated based on the use condition of this printer and the viscosity of the ink is adjust by an ink viscosity adjusting means 140 consisting of a dilute solution cartridge 102, a dilute solution pump 114 and the like, thereby achieving an ink jet printer capable of using all the ink for the printing without lowering the printing quality and wasting the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer, and more particularly to an ink jet printer that collects waste ink not used for printing and reuses it for printing.

[0002]

2. Description of the Related Art In an ink-jet printer that performs recording by discharging ink, if a normal discharge signal is sent at the start of printing if the ink is left undischarged for a long time,
It is known that a defective phenomenon that ink is not normally ejected occurs. This is because the ink in the nozzle of the print head comes into contact with the outside air, the solvent in the ink evaporates, and the viscosity of the ink changes. It is.

[0003] As a countermeasure, a predetermined pressure is applied to the ink flow path, for example, by pressurizing the ink supply system or sucking the ink from the ink discharge port, thereby forcibly discharging the ink having increased viscosity near the nozzle. There is a way. In a conventional ink jet printer, as disclosed in Japanese Patent Application Laid-Open No. 8-132640, ink collected from a print head is discarded without using it.

There is also a method of performing preliminary discharge in which ink having increased viscosity in the vicinity of a nozzle is automatically discharged to a liquid absorber or the like a suitable number of times when ink discharge is not performed for a long time. -290720. However, the ink ejected in the preliminary ejection is discarded without being used.

[0005]

When the ink collected from the print head is discarded without reuse, if the print head has only a small number of nozzles, the amount of waste ink is small, and the waste ink gradually evaporates. For this reason, the waste ink holding means is also not small and a big problem, but an ink jet printer having a large number of nozzles has a large amount of waste ink, wastes a lot of ink, and requires a large ink holding means. In addition, a large-capacity waste ink holding means capable of continuously collecting waste ink is required, and the printer is increased in size, or the frequency of replacing the ink holding means is high and the printer is difficult to use.

Further, when the waste ink is directly collected and used in the ink holding means, the following problem occurs.

Since the outside air does not come into contact with the ink from the ink holding means to the ink supply path and the print head, the viscosity of the ink is hardly increased due to the evaporation of the solvent of the ink. In the cap means for this purpose, the outside air comes into contact with the ink, the solvent in the ink evaporates, and the viscosity of the ink changes.

[0008] Since the nozzles of the print head of the ink jet printer are adjusted to eject a small amount of ink, if the viscosity of the ink used changes, the amount and speed of the ink to be ejected changes. Ink collected from the print head has a change in viscosity due to the evaporation of a part of the solvent, so the ink landing position is shifted or, if color ink is used, the density variation among multiple color inks As a result, the printing quality was remarkably reduced, for example, the color of the printing result was different.

[0009] In particular, when the ink contains a volatile solvent such as alcohol, the viscosity of the ink greatly changes, and a problem easily occurs. Further, a problem easily occurs when the number of nozzles is large and the ink often comes into contact with the outside air, such as a line head.

[0010]

In order to solve the above-mentioned problems, an ink jet printer according to the present invention comprises an ink holding means, an ink supply means for supplying ink from the ink holding means to a print head, and a cap for holding the print head. Cap means, ink recovery means for returning ink from the cap means to the ink holding means, timing means for counting the pause time of printing, and preliminary ejection for counting the number of preliminary ejections of ink to be ejected before printing. The number of times measuring means, the number of print ejections measuring the number of inks used for printing, the equivalent of the viscosity of the ink in the ink holding means by the time counting means, the number of preliminary ejection times measuring means and the number of times of printing ejections measuring means An ink viscosity equivalent value calculating means for calculating a value; and an ink holding means based on the ink viscosity equivalent value calculating means. An ink viscosity adjusting means for adjusting the ink viscosity, by recovered ink reused while adjusting the viscosity, requires no waste ink holding means small,
In addition, it is possible to realize an ink jet printer that has a long ink replenishment interval, is economical, has a constant ink discharge speed and discharge amount, has good print quality, can use volatile ink, and has a fast drying property.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink jet printer according to an embodiment of the present invention will be described with reference to FIGS. The paper feed mechanism, the pressure generating mechanism of the nozzles in the print head, and the like are general ones used in an ink jet printer, and do not affect the gist of the present invention, so that the description is omitted.

FIG. 1 is a partially exploded perspective view of an ink jet printer according to an embodiment of the present invention. This ink jet printer has a print head 120 capable of printing over the entire width of the paper. The print head 120 does not move, and ink is ejected from the print head 120 in accordance with paper feed, thereby printing characters and symbols on a recording paper 130. ,
Images can be printed. Replenishment of ink and diluent
As shown in FIG. 2, the cartridge can be refilled by opening the cartridge cover 103 and exchanging the two cartridges, the ink cartridge 101 and the diluent cartridge 102, individually.

FIG. 3 is an explanatory diagram showing an ink supply system of the ink jet printer.

Ink is supplied from the ink cartridge 101 as the ink holding means to the print head 120 through the ink supply tube 108 as the ink supply means.

The print head 120 has a plurality of nozzles 120a having a pressure generating mechanism (not shown) for discharging ink. Since the ink in the nozzle 120a is in contact with the outside air, the volatile components are liable to evaporate. If the ink is ejected after a long pause, the print quality deteriorates due to an increase in the viscosity of the ink. Therefore, it is necessary to discharge the ink near the nozzle 120a before starting printing, and perform preliminary discharge of the ink into the cap 112 an appropriate number of times, or bring the cap 112 into close contact with the print head 120 and perform ink recovery as an ink recovery unit. Pump 10
9, suction of the thickened ink is performed. The collected ink is returned to the ink cartridge 101 through the ink collection tube 110. The ink in the ink cartridge 101 has a viscosity suitable for ink ejection when the ink cartridge 101 is replaced, but the ink circulates for a long time,
As the collected thickened ink increases, the ink in the ink cartridge 101 also gradually increases in viscosity, and as it is, the ink ejection becomes unstable and the print quality deteriorates. Therefore, the ink jet printer of the present invention has the following ink viscosity adjusting means.

The ink viscosity adjusting means includes a diluent cartridge 102 containing a diluent composed of volatile components of the ink, a diluent pump 114, and a diluent tube 111. The viscosity of the ink in the ink cartridge 101 is predicted by the ink viscosity equivalent value calculation means 140,
The controller 116 is notified. When the viscosity of the ink is larger than the specified value, the controller 116 drives the diluent pump 114 to inject the diluent from the diluent cartridge 102 into the ink cartridge 101 through the diluent tube 111 to adjust the viscosity of the ink.

Next, a method of estimating the viscosity of the ink in the ink cartridge 101 will be described with reference to the block diagram shown in FIG.

The timer 141 measures the pause time of printing and notifies the ink viscosity equivalent value calculator 140 of the measured data. In the ink viscosity equivalent value calculation means 140, the weight at which the ink volatile component evaporates in a unit time from the nozzle of the print head is measured by experiment, and recorded in advance,
Based on the data sent from the timer 141, the volatile weight of the ink volatile component due to the suspension of printing is calculated.

The number-of-preliminary-ejections counting means 142 measures the number of preliminary ejections performed prior to printing, and notifies the measured data to the ink viscosity equivalent value calculating means 140. The ink viscosity equivalent value calculation means 140 measures the number of times of preliminary ejection and the weight at which the ink volatile component volatilizes by experiment, records them in advance, and, based on the data sent from the number of times of preliminary ejection number measurement means 142, calculates the ink by the preliminary ejection. Calculate the volatile weight of the volatile component.

In addition, the weight of each ink droplet ejected from the nozzles of the print head is measured by an experiment, and recorded in the ink viscosity equivalent value calculation means 140 in advance. The print ejection number measurement unit 143 measures the ejection number of the ink used for printing, and calculates the ink viscosity equivalent value calculation unit 140.
To the measured data. Based on this data, the ink viscosity equivalent value calculation means 140 calculates the weight of the printing ink used for printing.

Further, the initial ink weight in the ink cartridge 101 and the initial ink volatile component weight ratio are recorded in the ink viscosity equivalent value calculation means 140 in advance. As described above, the volatile weight of the ink volatile component and the weight of the printing ink used for printing are calculated by the ink viscosity equivalent value calculating means 140.
Therefore, the ratio of the weight of the ink in the ink cartridge 101 to the weight of the ink volatile component can be calculated in accordance with the usage status of the inkjet printer.

There is a fixed relationship between the ink volatile component weight ratio and the ink viscosity. As shown in FIG. 5, the relationship between the volatile component weight ratio in the ink and the ink viscosity can be determined by experiment. By recording this relationship in advance in the ink viscosity equivalent value calculation means 140, it is possible to predict the ink viscosity in the ink cartridge 101 from the weight ratio of the ink volatile components in the ink cartridge 101. When the viscosity of the ink is larger than the specified value, the ink viscosity equivalent value calculating means 140
A signal is sent to 16 to drive the diluent pump 114.

FIG. 6 is a sectional view of the ink cartridge 101 accommodating portion, and also shows a section of the ink cartridge 101. An ink cartridge 101 serving as an ink holding unit for holding ink therein has an ink supply port 101a for supplying ink to the print head 120, and an ink collection port for taking in ink or a diluent from the cap 112 and the diluent cartridge 102. 101b, a filter 101c for filtering foreign matter in the ink returning from the ink recovery port 101b into the ink cartridge 101 is provided. The ink is supplied to the print head 120 from the needle 108a pierced into the ink supply port 101a through the ink supply tube 108. The flow path connecting lever 113 is connected to the ink collecting tube 110 and the diluent tube 111, and connects the ink collecting port 101b to the two tubes.

The replacement of the ink cartridge 101 is described in FIG.
Open the cartridge cover 103 upward. Then
Since the channel connecting lever 113 connected to the ink recovery port 101b of the ink cartridge 101 does not press the cartridge cover 103, the ink cartridge 101
Move away from Arrow A on the ink cartridge lever 105
When rotated in the direction, the gear 105a fixed to the ink cartridge lever 105 and the ink cartridge holder 1
04, the ink cartridge holder 104 is moved in the direction of arrow B,
08a comes out of the ink supply port 101a, and the ink cartridge 101 can be pulled upward. After setting a new ink cartridge in the ink cartridge holder 104, move the ink cartridge lever 105 to the arrow A
When the cartridge holder 104 is rotated in the opposite direction, the cartridge holder 104 moves in the opposite direction of the arrow B by the above-described reverse operation, and the needle 108a
Is stuck in the ink supply port 101a, and when the cartridge cover 103 is closed, the ink recovery port 101b and the flow path connecting lever 113 are connected, and the replacement of the ink cartridge 101 is completed.

The cross section of the diluting liquid cartridge 102 is almost the same as the cross section of the ink cartridge 101, but does not include the ink recovery port 101b, the filter 101c, and the ink sensor 115. The replacement of the diluent cartridge 102 is the same as the replacement of the ink cartridge 101.
07 can be easily replaced.

FIG. 7 is a sectional view of the vicinity of the print head 120 accommodating portion. The print head 120 has a plurality of nozzles 120a in a printable width, and is fixed to a printer frame (not shown). The cap 112 can move up and down (illustration and explanation of the mechanism of the up and down movement is omitted). During the printing operation, the cap 112 is drawn below the paper guide plate 131 so that the recording paper 130 can pass under the print head 120. When the printing is stopped after the recording paper 130 is ejected, the printing head 12 rises up and comes into close contact with the print head.
The ink inside 0 is prevented from drying. Also, when the thickened ink inside the print head 120 is collected, it rises and comes into close contact with the print head 120 to connect the print head 120 and the ink collection pump 109.

The printing operation of the ink jet printer is as follows.

At the time of a pause when printing is not being performed, the cap 112 is raised and is brought into close contact with the print head 120 to prevent the ink in the print head 120 from drying.

When printing is started, first, the ink recovery pump 109 is operated, and the nozzle 1 in the print head 120 is operated.
The thickened ink near 20a is sucked. After the ink recovery pump 109 stops, the cap 112 descends, separates from the print head 120, and stops at a position lower than the paper guide plate 131. Thereafter, the ink recovery pump 109 is operated again for a short time, and the ink in the cap 112 is also returned to the ink cartridge 101.

When the paper feed roller 132 rotates and the recording paper 130 is inserted below the print head 120, the pressure generating mechanism of the nozzles arranged in the print head 120 is selectively driven to discharge ink and print. Is done. The recording paper 130 passes under the print head 120 by the paper discharge roller 133, and the printing ends. After that, the cap 112 moves up and comes into close contact with the print head 120 and stops.

When printing on another recording paper, the ink recovery pump 109 does not operate, the cap 112 descends and separates from the print head 120, and the paper guide plate 131 is moved.
Stop at a lower position. Next, the print head 12
All the pressure generating mechanisms of the nozzles 120a within 0 are driven to perform preliminary ejection toward the cap 112. When printing is performed continuously in this manner, preliminary ejection is performed from all nozzles, and ink whose viscosity has been increased from nozzles that have not been ejected during printing is discharged to the cap 112. After that, printing is performed.

When printing of a predetermined number of sheets is completed, the ink collecting pump 109 is operated for a short time to collect the ink of the cap 112 collected by the preliminary ejection into the ink cartridge 101.

As described above, the thickened ink recovered from the cap 112 is mixed into the ink in the ink cartridge 101, so that the thickened ink has a small amount of volatile components in the ink. When the viscosity of the ink increases, the ink discharge capability of the print head 120 decreases, and the print quality deteriorates. Ink viscosity equivalent value calculation means 140
Indicates that the ink cartridge 10 is
1 and predicts the viscosity of the ink in the case where the viscosity of the ink is high.
4 is driven to add the diluent from the diluent cartridge 102 to the ink cartridge 101. By providing such an ink viscosity adjusting means, it is possible to prevent a decrease in print quality and maintain good print quality until the ink in the ink cartridge runs out.

In the above embodiment, an ink jet printer using a line head fixed to a print head has been described as an example. However, the present invention is not limited to an ink jet printer using a line head. It goes without saying that the present invention is also applied to a serial printer that prints while moving.

[0035]

As described above, in the ink jet printer of the present invention, the ink discharged from the print head is also collected and reused, so that all the ink can be used for printing, and the ink replenishment interval is long and economical. No need for waste ink holding means, compact size, constant viscosity of ink supplied to print head, stable weight and speed of ink ejected from print head, and clean printing without ejection failure A simple inkjet printer can be realized. In particular, unlike a continuous ink jet printer, in an on-demand ink jet printer having a small ejection energy, the influence of the viscosity of the ink on the print quality is great, and the effect of maintaining the ink viscosity at a constant level is large. Further, when a quick-drying ink containing a volatile solvent is used, the effect is large. It is particularly effective for an ink jet printer using a line head having a large number of nozzles.

[Brief description of the drawings]

FIG. 1 is a partially exploded perspective view of an ink jet printer of the present invention.

FIG. 2 is an explanatory diagram of cartridge replacement of the ink jet printer of the present invention.

FIG. 3 is an explanatory diagram of an ink supply system of the ink jet printer of the present invention.

FIG. 4 is a block diagram showing an embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between the ink volatile component weight ratio and ink viscosity.

FIG. 6 is a sectional view of an ink cartridge accommodating portion of the ink jet printer of the present invention.

FIG. 7 is a sectional view of a print head accommodating portion of the ink jet printer of the present invention.

[Explanation of symbols]

 101 Ink Cartridge 102 Diluent Cartridge 103 Cartridge Cover 104 Ink Cartridge Holder 105 Ink Cartridge Lever 106 Diluent Cartridge Holder 107 Diluent Cartridge Lever 108 Ink Supply Tube 109 Ink Recovery Pump 110 Ink Recovery Tube 111 Diluent Supply Tube 112 Cap 113 Channel Connecting lever 114 Diluent pump 115 Ink sensor 116 Controller 120 Print head 130 Recording paper 131 Paper guide plate 132 Paper feed roller 133 Discharge roller 140 Ink viscosity equivalent value calculation means 141 Clocking means 142 Preliminary discharge count measuring means 143 Print discharge count measurement means

Continuing from the front page (72) Inventor Tsutomu Yamazaki 3-5-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (72) Inventor Toshio Nakata 3-5-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation F-term (reference) 2C056 EA19 EA23 EA25 EA27 EB08 EB29 EB32 EB38 EB49 EB59 EC15 EC24 EC44 EC54 EC57 FA13 FC01 JA13 JC20 JC23 KB15 KC01 KC30

Claims (3)

[Claims] An ink jet printer which has a pressure generating means and has a plurality of nozzles for selectively discharging ink, and moves a print head relative to a recording medium to print characters, symbols, images, and the like. Ink holding means, ink supply means for supplying ink from the ink holding means to the print head, cap means for capping the print head, ink recovery means for returning ink from the cap means to the ink holding means, and printing pause A time counting means for counting time, a preliminary ejection number measuring means for measuring the number of preliminary ejections of ink to be preliminary ejected prior to printing, a printing ejection number measuring means for measuring the number of ink ejections used for printing, and the timing means; The equivalent value of the viscosity of the ink in the ink holding unit is measured by the preliminary ejection number measurement unit and the print ejection number measurement unit. Inkjet printer characterized in that it has an ink viscosity adjusting means, wherein the ink viscosity equivalent value calculating means based on the ink viscosity equivalent value calculating means for adjusting the ink viscosity in the ink holding means for. 2. The ink jet printer according to claim 1, wherein an ink containing a volatile solvent is used. 3. The line inkjet printer according to claim 1, wherein the print head has a number of nozzles that can be printed in a print area width of the recording medium.