JPH11309873A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent clogging of unused ink ejection hole during print operation by providing a shutter mechanism for opening/closing each ink ejection hole independently. SOLUTION: A shutter mechanism for opening/closing each ink ejection hole independently is provided. A shutter 3b in the shutter mechanism for ink ejection holes 2a, 2b touches the ink ejection hole 2b when a coil 10b is not conducting because a magnetic circuit is formed by the magnetic force of a permanent magnet 12b and a leaf spring 15b is not deformed. When a coil 10a is conducted, electromagnetic force overcomes the magnetic force of the permanent magnet to separate a leaf spring 15a thus separating the shutter 3a from the ink ejection holes 2a and ejecting ink particles 16. This structure prevents clogging of an ink ejection hole not used for a long term even during print operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The object of the present invention is an ink jet recording apparatus. In particular, in an ink jet recording apparatus using ink which is excellent in quick-drying and is liable to cause clogging in an ink ejection hole, printing is performed during a printing operation of the apparatus. The present invention relates to an ink jet recording apparatus having means for preventing clogging of an ink ejection hole which is not used.

[0002]

2. Description of the Related Art Conventionally, as means for preventing ink clogging of an ink ejection hole, (1) a head is moved and engaged with a cap (Japanese Patent Publication No. 3-54057), and (2) printing is not performed for a certain period of time. The ink ejection hole is ejected idly (Japanese Unexamined Patent Publication
JP-A-164261), (3) opening and closing the shutter (JP-A-2-122934), and (4) washing after sealing the ink ejection holes (JP-A-4-39055).

[0003]

The technique of the above (1) is:
Although effective in preventing clogging of the ink ejection holes when printing operation is stopped, there is a problem that it cannot be applied to prevention of clogging during operation. The technique (2) has a problem that a large amount of electric power is instantaneously consumed for performing the idle discharge, and an idle discharge device is required. The technique (3) is a mechanism that opens and closes a plurality of holes at once, and thus has a problem that it is not useful for preventing clogging of ink ejection holes not used for printing during printing operation. The technique (4) requires a circulating system for recovering and supplying the cleaning liquid, and therefore has a problem that it is a large-scale apparatus when applied to an apparatus having a plurality of holes.

Accordingly, it is an object of the present invention to provide an ink jet recording apparatus which realizes prevention of clogging of an ink ejection hole which is not used for printing for a long time during a printing operation of the ink jet recording apparatus by simple means.

[0005]

In the present invention, a shutter mechanism is used to prevent clogging of the ink ejection holes. However, an electrostrictive element, an electromagnet, and the like, which can independently control the prevention of clogging of each ink ejection hole, are driven. A small shutter mechanism as an element is used. By doing so, it is possible to prevent clogging of the ink ejection holes during a printing operation with low power consumption.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to an ink jet recording apparatus having a plurality of ink ejection holes, and relates to a means for preventing clogging thereof.

Regarding the cause of clogging of the ink ejection hole,
This will be described with reference to FIG. The ink includes a pigment (dye or pigment) and a solvent for dissolving the pigment. The saturated vapor pressure of the ink solvent has a relationship with the ambient temperature as shown in FIG. 9. When the ambient temperature rises, the saturated vapor pressure (the difference between the gauge pressure and the atmospheric pressure) increases, and the ink ejection hole is formed in the atmosphere. When open, evaporation of the solvent is promoted. As a result, the dye is solidified in the ink ejection holes, causing clogging.

In order to prevent clogging of the ink ejection holes,
The purpose is to always keep the ink ejection holes at a pressure higher than the saturated vapor pressure. As one of the measures, there is a means for sealing the ink ejection hole and preventing the solvent vapor from being released into the atmosphere. The pressure in the sealed space rises to the saturated vapor pressure, and the pressure exceeding the saturated vapor pressure liquefies, so that clogging of the ink ejection holes can be avoided. Means for sealing the ink ejection hole outlet include a cap and a shutter.

A first embodiment of the present invention will be described with reference to FIGS. FIG. 2 shows the overall configuration of the ink jet recording apparatus of the present invention, FIG. 3 shows an example of recording characters using the ink jet recording apparatus of the present invention, and FIG. 4 shows the ink ejection section and shutter section of the ink jet recording apparatus of the present invention. 5 shows a power supply pattern of a driving element of a shutter section of the ink jet recording apparatus of the present invention, and FIG. 6 shows an ink ejection section of the ink jet recording apparatus of the present invention.
13 shows another configuration example of the shutter section.

The ink jet recording apparatus according to the present invention is shown in FIG.
As shown in (1), the structure is such that the ink ejection hole 2 can be closed by the shutter 3, and a feature is that a shutter corresponding to each ink ejection hole is provided. The print medium 4 (for example, paper) is driven, for example, in the direction of arrow 5 (in this figure, it moves forward from the ink ejection holes 2). Head part 1
Depending on the size of the character to be printed, can be used in an inclined manner with respect to the transport direction of the print medium as shown in the figure.

The ink particles ejected from each of the holes collide with the print medium, and characters such as those shown in FIG. 3 are printed.
FIG. 3 shows an example of two-stage printing. There is a space between "A" and "C" in the figure, but no ink particles are ejected from the ink ejection holes corresponding to this space. In particular, when printing a serial number on a production line or the like, printing with such a specific printing pattern may be performed for a long time. In this case, if the space is not closed by a shutter or the like, clogging occurs.

Therefore, as shown in FIG. 2, the shutters 3a, 3b
Blocking can prevent clogging. In addition to two-stage printing, character patterns to be printed include three-stage printing and four-stage printing. Since the ink ejection holes 2 corresponding to the space between stages change depending on the usage, each ink ejection hole can be opened and closed independently. A simple shutter is required.

Next, a specific configuration of the ink jet recording apparatus of the present invention will be described with reference to FIG. FIG.
-It is an A section. The principle of ink ejection will be described. The ink is led from the ink tank 6 to the ink chambers 24a and 24b by a head difference or a pump through the ink supply pipe 2, a pulse-like voltage is applied to the electrostrictive elements 8a and 8b, and the diaphragms 9a and 9b are deformed. , 24b, the ink particles 16 are ejected.

The shutter mechanism of the ink ejection holes 2a and 2b will be described. This shutter mechanism is a shutter mechanism driven by an electromagnet. The shutter 3b is a coil 1
0b when the current is not supplied, the dashed line 14 indicates the magnetic force of the permanent magnet 12b.
Is formed, the leaf spring 15b is not deformed,
The shutter 3b is in contact with the ink ejection hole 2b. Here, when the coil 10a is energized, the electromagnetic force overcomes the magnetic force of the permanent magnet and separates the leaf spring 15a, so that the shutter 3a separates from the ink ejection hole 2a and can eject the ink particles 16 as illustrated.

FIG. 5 shows the current pattern of the shutter drive element (coil) in this case. From this, in this shutter mechanism, when the shutter is opened, the energizing current becomes the maximum value (Imax
), The coil current becomes zero when the shutter is sealed. In the transition state between the open state and the sealed state, an intermediate current value is shown.

Next, another configuration of the ink jet recording apparatus of this embodiment will be described with reference to FIG. This apparatus shows a case where the ink ejection unit has the same configuration as that of FIG. 4, but the driving element of the shutter mechanism is an electrostrictive element. In FIG. 6, when the electrostrictive element 17b is not energized, the displacement magnifying mechanism 24b composed of an elastic hinge for magnifying the displacement is not driven, and the shutter 3b is in contact with the ink ejection hole 2b. Here, when a DC voltage is applied to the electrostrictive element 17a, the electrostrictive element is displaced as shown by an arrow 25a, and the displacement is changed by arrows 25b, 25c, and 25 by a three-stage displacement magnifying mechanism 24a.
The displacement is enlarged as shown by d, and the shutter 3a is separated from the ink ejection hole 2a. Also in this case, the energization pattern of the shutter driving element (electrostrictive element) is the same as that shown in FIG.

As described above, by using the ink jet recording apparatus of this embodiment, it is possible to provide a structure in which the ink ejection holes which are not used for a long time during the printing operation are not clogged even during the printing operation.

However, when the energizing pattern shown in FIG. 4 is used, when printing the same character repeatedly for industrial use, etc., the shutter of the ink ejection hole for continuously printing must be kept open, so that the power consumption is reduced. The problem that the number increases. Therefore, unless a power reduction measure such as opening and closing a shutter is taken every time printing is performed, it is difficult to continuously use for a long time due to a rise in coil temperature.

Next, a second embodiment of the present invention will be described with reference to FIGS. 7, 8, 10 and 11. The present embodiment shows a configuration in which power supply is not required at the time of holding the shutter open and also at the time of holding the seal, thereby reducing power. FIG.
Shows the configuration of the ink jet recording apparatus of the second embodiment of the present invention, FIG. 8 shows the energization pattern of the shutter drive element of this embodiment, FIG. 10 shows an example of the appearance of the ink jet recording apparatus of this embodiment, FIG. 11 shows another example of the appearance of the ink jet recording apparatus of this embodiment.

The construction of the ink jetting section of this embodiment is the same as that of the first embodiment, and a description thereof will be omitted. Here, the shutter mechanism is constituted by a pair of electrostrictive elements 18 and 19 displaced in the direction of arrow 14 arranged orthogonally, and is constituted by an elastic hinge which is rigid in the direction of displacement of the electrostrictive element and soft in the orthogonal direction. The displacement synthesizing unit 20 synthesizes the displacements, and the shutter 3 is driven by frictionally driving the shutter 3 pressed between the bearing 21 and the displacement synthesizing unit 20 to drive the shutter.

The electrostrictive elements 18 and 19 can be driven by applying an AC voltage having a phase difference in a transition state from open to sealed, for example, as shown in FIG. In the transition state from the sealing to the opening, the electrostrictive element 18 is driven alone, and in the transition state from the opening of the shutter 3 to the sealing, the electrostriction element 19 is driven alone to realize the opening / closing operation of the shutter. it can.

FIG. 8 shows a case where the electrostrictive element is driven by an AC voltage to which a bias voltage is applied. However, the element may be driven by an AC voltage having a negative voltage. FIG. 1 shows an example of the appearance of such an ink jet recording apparatus. Shutter 3a
Has a configuration in which a dog 22 is provided, the position of which is detected by the proximity sensor 23, and the timing at which shutter opening and closing ends are detected.

Another example of the appearance of the ink jet recording apparatus is shown in FIG. In this device, the dog 22 is attached to the shutter 3a.
Are provided, and stoppers 26a, 26b are provided on the head 1 side.
Are provided, and the dog and the stopper are located at relative positions corresponding to the shutter open and seal end positions. Therefore, when the dog 22 contacts the stopper 26, the electrostrictive element 1
By detecting the timing when the energizing currents 8 and 19 increase, the shutter open position and the sealing position can be detected.

By using the ink jet recording apparatus having such a configuration, it is not necessary to energize both when the shutter is kept open and when the seal is kept, so that the power can be reduced.

Further, since the adhesion of the ink to the shutter of the shutter mechanism described in the first and second embodiments becomes a problem, the adhesion of the ink can be prevented by performing the water-repellent treatment on the shutter 3. A highly reliable shutter opening / closing operation for a long time can be performed. As the water-repellent material, for example, a fluorine compound containing a perfluoropolyoxyalkyl-based compound having a silanol group at a terminal and having a molecular weight of 3,000 or more capable of obtaining a large contact angle when an ink droplet is dropped on a shutter is used. A great effect can be obtained.

[0026]

Since the ink jet recording apparatus of the present invention is configured as described above, the following effects can be obtained.

(1) In the ink jet recording apparatus of the present invention, since the shutter mechanism is provided so as to be independently openable and closable corresponding to each of the ink ejection holes, the shutter mechanism is not used during the printing operation regardless of the character pattern to be printed. Clogging of the ink ejection holes can be avoided.

(2) In the ink jet recording apparatus of the present invention, since the shutter mechanism is realized by a friction drive system,
The shutter function can be realized without supplying electric power both when the shutter is held open and when the shutter is held, and clogging of the unused ink ejection holes during the printing operation can be avoided with small power consumption.

(3) In the ink jet recording apparatus of the present invention, the shutter of the shutter mechanism is subjected to water-repellent treatment.
Ink can be prevented from adhering to the shutter, and a long-term stable operation of the shutter mechanism can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of the appearance of an ink jet recording apparatus according to the present invention.

FIG. 2 is a sectional view showing a basic configuration of the ink jet recording apparatus of FIG.

FIG. 3 is a plan view showing a printing example of the ink jet recording apparatus of the present invention.

FIG. 4 is a side sectional view showing the configuration of the ink jet recording apparatus according to the first embodiment of the present invention.

FIG. 5 is a characteristic diagram showing an energization pattern of a shutter driving element according to the first embodiment of the present invention.

FIG. 6 is a side sectional view showing another configuration of the ink jet recording apparatus according to the first embodiment of the present invention.

FIG. 7 is a side sectional view showing a configuration of an ink jet recording apparatus according to a second embodiment of the present invention.

FIG. 8 is a characteristic diagram showing an energization pattern of a shutter driving element according to a second embodiment of the present invention.

FIG. 9 is a characteristic diagram showing a relationship between a saturated vapor pressure of an ink solvent and an ambient temperature.

FIG. 10 is a perspective view showing the appearance of another inkjet recording apparatus according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Head part, 2 ... Ink ejection hole, 3 ... Shutter, 4 ...
Print medium, 5: print medium transport direction, 6: ink tank,
7 ... ink supply pipe, 8, 17, 18, 19 ... electrostrictive element,
9 ... diaphragm, 10 ... coil, 11 ... core, 12 ...
Permanent magnet, 13: Displacement direction of electrostrictive element, 14: Magnetic circuit, 15: Leaf spring, 16: Ink particle, 20: Displacement synthesizing unit, 21: Bearing, 22: Dog, 23: Proximity sensor, 24
... Displacement enlargement mechanism, 25... Deformation direction, 26.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshio Ouchi 1-1-1, Higashitaga-cho, Hitachi City, Ibaraki Prefecture Inside the Taga Headquarters, Electrical Equipment Division, Hitachi, Ltd. (72) Takashi Minegishi Hitachi, Ibaraki Prefecture 1-1-1, Higashitaga-cho, Hitachi City

Claims (1)

[Claims] 1. An ink jet recording apparatus having a plurality of ink ejection holes, comprising a shutter mechanism capable of independently opening and closing each ink ejection hole.