JPH01259961A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To accurately eject hotmelt type ink by providing a platelike member having a plurality of nozzles in a casing with a thermal conductive material having a heat source, and pressurizing melted and liquefied ink by piezoelectric conversion means disposed through a spacer on the rear face of the member to inject it from a nozzle opening. CONSTITUTION:When the lower face of a casing 3 passes a heat generating element 4, the casing 3 made of a thermal conductive material is wholly heated equally, solidified ink sealed in a narrow gap D of an ink chamber 21 is melted to momentarily become a printable state. When a pattern electrode 13 is selectively energized in response to recording information in this state, a piezoelectric converter 10 to mounted as to exposed the top of the ink mostly with a supporting base 16 disposed upside is vibrated with corresponding vibrators 15 of a plurality of vibrator 15 of pectinated toothlike state directed toward a nozzle plate 8. The ink is pressurized between the plate 8 and a control plate 22 to be efficiently injected as ink droplets from a nozzle 7 opened immediately before it and to adhere to recording sheet(s) on a platen 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an inkjet recording apparatus, and more particularly to an inkjet recording apparatus using hot melt ink.

(Prior Art) An inkjet recording device in which a nozzle plate having a plurality of nozzle openings and a piezoelectric transducer that pressurizes the ink by directly contacting the ink is disposed on the spine of the nozzle plate is disclosed in Japanese Patent Publication No. 60-8953. ing. In this recording printing, the vibrator constituting the piezoelectric transducer vibrates in a direction almost perpendicular to the nozzle plate, and the ink flow path between the nozzles is short, so ink droplet ejection efficiency and safety are high. Moreover, even if gas or dust gets mixed into the ink, it will operate normally without being affected by it, and as a cantilevered vibrator, its rigidity is small. It has the advantage of being able to provide the required moving part displacement. However, on the other hand, in this type of device, it is necessary to submerge the piezoelectric transducer in the ink, so it is necessary to use a non-conductive ink, for example, an oil-based ink containing an organic solvent as the main component. For this reason, when printing on rough paper, etc. using this type of ink, if the ink droplets adhere to the recording paper, they bleed into the surrounding area, making the outline unclear and the density low, reducing the print quality. I have a problem.

Of course, for such problems, for example,
If the inkjet recording device T8 as disclosed in Publication No. 98547 is used, printing quality can be maintained at a high level because the ink used is a hot melt type, but on the other hand, this type of ink is Air bubbles are always generated when a phase change occurs from a solid phase to a liquid phase, and as a result, even if the ink is pressurized by a piezoelectric transducer, the air bubbles absorb this pressure and the ink does not function properly. This causes the problem that it is not possible to discharge the liquid.

(Problems to be Solved by the Invention) The present invention has been made in view of these problems, and its purpose is to enable accurate ejection of hot-melt ink, thereby achieving the advantages of this type of ink. An object of the present invention is to provide a new inkjet recording device M that can fully exhibit high-quality printing functions.

(Means for Solving the Problems) That is, the present invention provides an inkjet recording device for achieving the above-mentioned problems, which includes: a housing made of a thermally conductive material that is disposed to face a recording medium and equipped with a heat source; A plate-shaped member having a plurality of nozzle openings disposed in a housing, a piezoelectric conversion means disposed on the rear surface of the base end of the plurality of vibrators via a spacing regulating member, and the plate-shaped member and the piezoelectric conversion means. Hot melt ink The ink is ejected accurately and effectively to achieve the high printing performance that is an advantage of this type of ink.

(Example) Therefore, the illustrated embodiment will be explained below.

Figure 1 shows a cross section of an inkjet head.
The inkjet head 1 is mounted on a carriage (not shown) that runs in the axial direction of the platen 2.

Reference numeral 3 denotes a casing for the inkjet head 1 formed into a container shape from a metal material with good thermal conductivity.A heating element 4 is attached to the bottom surface of the casing 1, and a platen 2 is roughly connected to the casing 3.
On the side surface 5, a required number of ink droplet ejection holes 6 are arranged in a row in the direction of the platen axis, and on the inside of this surface 5,
A plurality of nozzles 7 corresponding to the ink droplet ejection holes 6...
A nozzle plate 8 having a row of nozzle plates 8 arranged in a row is integrally attached with a spacer 9 interposed therebetween.

10 is a smooth piezoelectric transducer attached to the back of this nozzle plate 8 via a spacer 17, and this piezoelectric transducer 1o is a second piezoelectric transducer.
As shown in the figure, a piezoelectric element 11 made of PZT has a common electrode 2 on one side and a pattern electrode 13 on the other side, and cuts 14 at intervals equal to the pitch of the nozzles 7 from the negative side. . . , a plurality of vibrators 15 . The piezoelectric transducer 10 configured in this manner has each vibrator 15 and
... are attached to the back surface of the nozzle plate 8 with minute intervals corresponding to the thickness of the spacer 17, with the supporting base 16 facing upward, and with the tips of each facing the nozzle 7... Lead wire 18 to pattern electrode 13...
When a voltage is selectively applied through..., the corresponding vibrator 15 vibrates in a direction perpendicular to the surface of the nozzle plate 8,
It is configured to press the ink interposed between the nozzle plate 8 and the vibrator 15 and eject it from the nozzle 7 onto the platen 2 and toward the recording paper S.

On the other hand, a reservoir tank 2 is located behind the piezoelectric transducer 1o.
A regulation plate 22 for regulating the interval between the ink chambers 21 is provided between the nozzle plate 8 and the protrusion 2 that supports the nozzle plate 8 from the rear.
3, the distance between the nozzle plate 8 and the regulation plate 22 is 0.2 to 2.
．． The ink chambers 21 are formed at intervals of about 0 mm. This gap is caused by the capillary action of the ink in the ink chamber 21, which is configured so that only the ink level is always below the axis of the nozzle 7, as will be described later. The gap must be small enough to allow the carriage to be pulled up to a point above the axis and at the same time to suppress fluctuations in the ink surface when the carriage moves. In addition to being able to release ink, it must also have a gap that allows for continuous ink ejection without causing ink shortage, and that can respond sufficiently to high frequency ink ejection. The regulating plate 22 is positioned by the above-mentioned protrusion 23 so that a gap satisfying this condition is formed between the regulating plate 22 and the nozzle plate 8.

By the way, the above-mentioned casing 3 is provided with a cover 31 that covers the reservoir tank 20 at a position lower than the axis of the nozzle 7, so that the liquid level of the molten ink is always lower than the axis of the nozzle 7. managed. Although not shown, this reservoir tank 2
0 is provided with a lower limit liquid level detection sensor, and when the ink liquid level reaches the lower limit and is detected by this sensor, a volume of solid ink (not shown) is removed from the solid ink storage tank to an extent that does not exceed the nozzle 7 axis a. The structure is such that an ink mass having a certain amount of ink is supplied into this reservoir tank 2o.

Note that the reference numeral 24 in the figure indicates the reservoir tank 20 and the ink chamber 2.
1 and 24, and 25 represents a filter installed at the entrance of this flow path 24.

In the recording apparatus configured as described above, when current is applied to the heating element 4 on the lower surface of the casing 3 to perform a printing operation, the entire casing 3 made of a heat conductive material is heated equally, and the narrow gap in the ink chamber 21 is heated first. It melts the ink that has solidified while it is still sealed inside the container, making it instantly ready for printing.

Therefore, in this state, if the pattern electrode 13 is selectively energized to record information (accordingly, the piezoelectric transducer 10, which is mounted with the support base 16 facing upward and most of it exposed above the ink), the comb-teeth Corresponding vibrators 15 out of a plurality of vibrators 15 forming a shape are efficiently and stably vibrated toward the nozzle plate 8, and pumped up by capillary action by fmD between the nozzle plate 8 and the regulating plate 22. The ink is pressurized and is efficiently ejected as ink droplets from a nozzle 7 opened just before the ink to be attached to the recording paper S on the platen 2.

On the other hand, the ink that was in a solid state in the reservoir tank 20 is rapidly melted from below by the heating element 4 on the bottom surface of the casing 3, and as it becomes liquefied, the convection effect transfers heat to various parts. The ink enters the uniformly heated flow path 24 of the metal casing 3 and is sequentially supplied to the ink chamber 21 without stagnation.

In this way, the specified printing operation is completed, and finally the power is turned off.
When set to FF, as the casing 3 cools, the ink chamber 2
Due to its small heat capacity, the small amount of ink indoors inside 1 quickly solidifies and fixes the vibrator 15, and then enters a resting state while preventing deformation of the vibrator 15 from the contraction force caused by the solidified ink in other parts. .

(Effects) As described above, according to the present invention, a plate-like member having a plurality of nozzles is provided in a casing made of a thermally conductive material equipped with a heat source, and the piezoelectric conversion means is arranged on the back surface of the plate-like member with a spacer interposed therebetween. Since the ink that has been molten and liquefied is pressurized and ejected from the nozzle opening, when electricity is applied to the heat source, the small amount of ink remaining between the plate-like member and the piezoelectric conversion means is quickly liquefied, allowing printing in a short time. At the same time, at the end of printing, the ink in this part is quickly solidified to fix the piezoelectric conversion means, thereby preventing the piezoelectric conversion means from being deformed by the condensation force in other parts. Furthermore, by making the ink ejection path as short and accurate as possible, the ink drawn up by capillary action can be effectively and stably ejected as ink droplets, taking advantage of the characteristics of hot melt ink. ) A clear image can be formed on the recording medium.

[Brief explanation of the drawing]

FIG. 1 is a side view of a device showing an embodiment of the present invention, and FIG. 2 is a perspective view of a piezoelectric transducer. 1... Inkjet head 2... Platen 3... Casing 4.
... Heating element 7 ... Nozzle 8 ... Nozzle plate 9 ... Spacer 10 ... Piezoelectric transducer 15 ... Vibrator 16 ... Support base
17... Spacer 18... Lead wire 2o... Reservoir tank 22... Spacing regulation 24... Ink passage Applicant Seiko Epson Corporation Agent Patent attorney Keiji Nishikawa No. 1 figure

Claims (1)

[Claims] A housing made of a thermally conductive material and provided with a heat source and arranged to face a recording medium; a plate-shaped member having a plurality of nozzle openings arranged in the housing; and a back surface of the proximal end of a plurality of vibrators. a piezoelectric transducer disposed through a spacing regulating member; disposed so as to form a gap between the plate-like member and the piezoelectric transducer to allow ink to be drawn up by capillary action; An inkjet recording device comprising: a gap regulating member having a passage for supplying ink from an ink reservoir to the gap.