JPS61141563A - Ink injector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to an ink ejection device for ejecting small droplets of ink, and more particularly to an ink ejection device for ejecting small droplets of ink, and more particularly to a more effective head structure and improved fluid tracking in a manifold. The present invention relates to an ink ejecting device having an ink supply mechanism that provides an ink supply mechanism.

[Conventional technology]

In the field of ink ejection devices, a reservoir containing ink, a manifold for supplying ink to a row of multi-conduit inlet restrictors, and some form of flow from the manifold to a relatively remote ink reservoir. Ink supply devices are commonly provided that include a channel. multiple conduits, e.g. 3
In systems with two conduits, there is the problem of minimizing rock noise in the form of pressure disturbances and pressure waves through the manifold. Noise-type disturbances are generally characterized by the development of pressure impulses in the manifold due to small volume jets of liquid resulting from jet pulsations. To reduce such noise, one standard device is to configure the manifold to provide an inlet restrictor passage with as much fluid compliance as possible, and the magnitude of the pressure wave to be It is inversely proportional to such followability. This compliance value is a function of both the compressibility of the liquid volume and the flexibility of the walls surrounding the liquid. Manifold compliance is also important to minimize the effects of external shock and vibration, which in some cases would interfere with the readiness of the device. The approach to solving this problem was to introduce a device that could provide greater followability by forming the main part of the manifold wall with a thin diaphragm with good followability.

Construction of a manifold to maximize its compliance generally requires increasing the dimensions of the manifold to obtain the necessary flex compliance of the diaphragm. This results in a larger than optimal ink ejection head requiring an ink reservoir located a considerable distance from the manifold. Because of this requirement, various configurations have been considered, generally including a tortuous flow path from the reservoir to the manifold. In this example, even though the reservoir itself exhibits near-infinite fluid compliance, the resistance of the connecting passages prevents the manifold from taking advantage of this compliance. Therefore, the manifold structure itself essentially has to take on all the work of minimizing noise and the effects of external shocks or disturbances, and generally does not benefit from the advantageous tracking characteristics of the reservoir. I end up. The device that makes the most effective use of the manifold's tracking characteristics is suitable for larger prints.
This may involve changing to a larger manifold configuration and relocating the reservoir away from the inlet restrictor. Such problems therefore pay for the need for larger and bulkier printheads, which are clearly disadvantageous.

One problem resulting from the large size of the manifold is the generation of air bubbles when filling the device with ink. Supplying ink from a relatively small inlet to a relatively large manifold is associated with excessive air bubble generation. Of course, if the manifold were larger, then one would have to suffer the penalty of additional space required if the inlet tube were made larger to reduce air bubble problems.

[Problems to be solved by the invention]

One object of the present invention is to have a manifold/reservoir that takes the most effective advantage of noise interference and air bubble generation, without the need to replace conventional structures, and with minimal printhead size. It is another object of the present invention to provide an ink ejection device with a short ink flow path.It is another object of the present invention to provide a manifold structure that provides a high degree of fluid compliance without requiring the use of compliant materials in the manifold itself. An object of the present invention is to provide an ink ejecting device having the following features.

Yet another object of the present invention is to provide an ink ejection device having a short ink supply passage configured to minimize device volume and reduce air entrapment problems during initial filling of the device with ink. [Means for Solving the Problems] For these and other purposes, the ink ejection device of the present invention has an ink ejection chamber portion including a plurality of ink ejection chambers in one row. at least one placed very close together
a manifold device for supplying ink from the reservoirs to these chambers, comprising a reservoir having two parts and a narrow manifold having a very short supply tube for connection to the reservoir; The supply pipe and the manifold have substantially the same cross-sectional shape. This narrow manifold is suitably configured as a groove in the transducer support structure, and its rounding is such that the manifold does not include any highly compliant elements.

The short length of the inlet supply tube and the alignment of this supply tube with the manifold effectively bring the high tracking characteristics of the reservoir to the room inlet, thereby reducing noise and This results in reduced air entrapment when the device is filled with ink.

〔Example〕

gg1-[3, the relative arrangement of an ink ejection device having a reservoir 40 and a print head or ink jet head 30 coupled together is shown. The reservoir is defined by a housing containing ink 41 therein and has a vent or port 43 for supplying atmospheric pressure to the reservoir. An inlet/outlet 43 or other means not shown are used to introduce ink into the apparatus in the form of hot melt ink granules or other conventional flowable ink forms. The print head includes a transducer support portion 32 which supports a row of transducers 45 (see FIG. 4, 8).

As shown in FIG. 2, these transducers are vertically aligned in corresponding ink chambers 36, and actuation of the transducers creates a droplet of ink in a known manner. Further forward of the transducer support portion 32, FIGS. 3 and ! As shown in Figure 4b, a chamber plate 34 is shown housing a chamber 36 and a restrictor population 35. Each room is designed in a known manner, each with a population of 3
It communicates with manifold 39 through 5. In many ink jetting devices, the ink jetting head is of a laminar or plate construction, while the inlet restrictor 35 is here shown as a groove in the chamber plate, connecting the transducer section 32 and the chamber plate 34. It is understood that there may be one separate inlet restrictor plate inserted in between.

In a preferred embodiment, manifold 39 comprises a hemispherical groove in the front of transducer support portion 32. The transducer support portion 32Fi is suitably made of aluminum such that the grooved walls of the manifold are aluminum and do not exhibit any conformability. Manifold 39 communicates with reservoir 40 via manifold population 37 and is connected to reservoir 40 via manifold population 37.
Conveniently, 7 is a single hole drilled vertically through the transducer support 32. An inlet tube, indicated at 38, is press fit into the manifold inlet 37 and extends downwardly into the reservoir 40. Alternatively, the print head may have a rigid portion extending further downward into the reservoir and carrying the inlet hole 37.

As shown in FIGS. 2 and 3, a manifold 39 extends from the inlet 37 and runs adjacent to and along the array of transducers 45 and chambers 36, and contains a vent 48 at its distal end. . This vent hole 48 is normally covered or plugged, but is unplugged in preparation for operation. In another embodiment, the manifold 39 is positioned within the chamber plate as shown by the dotted hemispherical line opposite the solid manifold line in FIG. The inlet tube communicates with the manifold groove in the chamber plate facing the front of the device.

The manifold is preferably hemispherical in cross-section;
Other geometries are within the scope of this invention. A radius of approximately 46 inches (1,59 cm) is preferred for a hemispherical shape. Regardless of the cross-sectional shape, the manifold is
The manifold population 37 is relatively narrow in terms of printhead size and volume and extends at a very small proportion to the vertical height of the printhead. , has a cross-sectional area very close to that of the manifold, providing fluidic alignment of the manifold and the inlet tube. Preferably, the cross-sectional area of the inlet 37 is no smaller than the cross-sectional area of the manifold. This alignment minimizes the fluid resistance as it appears from the inlet row towards the reservoir; and by increasing the inlet cross-sectional area, the problem of trapping bubbles in the manifold when the device is filled with ink is minimized. . In practice, the manifold should be approximately 2 inches (50,81
) length, the inlet is approximately 1 inch (25,4■) long, resulting in a total fluid path of approximately 3 inches (76,2■1); the inlet length is significantly smaller than the manifold length, and It is preferable to have a large area, such as an area at least as large as the space between the manifolds, thereby minimizing entrance resistance.
, 2 to 101.6 mm) was found to be sufficient for good operation up to and above the required drop firing rate of 10 KHz. .

The manifold/reservoir arrangement of the present invention, as described above, allows the manifold to be very narrow, thus also reducing the volume of the print head and keeping the reservoirs in close proximity to the manifold itself. In the illustrated embodiment, a portion of the reservoir extends below the manifold and chamber plate, with only about 1 inch (25,4 sm) from the reservoir to the manifold.
In ink jetting devices that require a wider manifold to obtain a higher degree of compliance than 0, the greater width of the manifold minimizes the vertical length of the head. The ink reservoirs are generally difficult to locate and require that the ink reservoirs be located a substantial distance from the back of the manifold. This results in a longer flow path, which results in a higher fluid ink resistance and, in effect, quickly disconnects the low compliance reservoir from the manifold due to pressure wave propagation.

In contrast, in the present invention, the inlet tube 37 is sized so that its cross-sectional area almost matches that of the manifold, so that the resistance is relatively low even when it is L-shaped as shown in FIG. flow path. This manifold also has no diaphragm to provide wall compliance; such a construction is based on the fact that relatively short and low resistance flow paths effectively connect the manifold directly to the reservoir. , is no longer needed, so it can be seen that essentially infinite reservoir tracking is available.

From the above it can be seen that the main advantage of the present invention derives from the fact that short feed tubes can be used in conjunction with narrow manifolds. A manifold consists of a single fermentor or tube and is itself It has a hard wall that does not exhibit significant fluid compliance. Matching the manifold to a short inlet tube provides a low resistance flow path to the reservoir, and thus a high conduction flow path, which reduces the generation of air bubbles during the ink filling process and makes the head more efficient. Filling becomes possible.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of the integrated reservoir and print head of the present invention; FIG. 1g2 is a cross-sectional view taken along line 2-2 in FIG. 1; and FIG. FIG. 4 is a detailed view of a portion of the print head showing the relationship between the manifold, ink jet chambers and transducers.・・・
Converter support part, 34... Draft plate, 35...
...Restrictor entrance, 36...Room, 37...
...Manifold inlet, 38...Inlet pipe, 39
...Manifold, 40...Reservoir, 4
3... Entrance/exit, 45... Converter, 48
...Vent hole 0

Claims (1)

[Scope of Claims] 1. An ink ejection chamber section including a plurality of ink ejection chambers, each chamber having an inlet and an orifice, and maintaining an ink supply under pressure and in close proximity to said chambers; reservoir means having at least one portion disposed therein; a manifold communicating with each chamber inlet; and a supply tube connecting the reservoir to the manifold, the supply tube and the manifold being substantially coincident; an ink supply means for supplying ink from the reservoir to the chamber, and having a cross-sectional shape. 2. A transducer support accommodating a row of transducers corresponding to the injection chamber, the supply tube being a passageway of substantially circular cross section passing through the support. The ink ejecting device according to item 1. 3. The ink ejecting apparatus according to claim 2, wherein the manifold includes a passage passing through the substantially hemispherical support portion. 4. The manifold comprises a passage through the chamber having a substantially hemispherical cross-sectional shape, and the supply tube has an outlet upwardly from the support communicating with the manifold. The ink ejecting device according to item 2. 5. The ink ejecting device according to claim 1, wherein the supply pipe has a relatively short length compared to the length of the manifold. 6. The ink ejecting apparatus of claim 1, wherein the supply tube is approximately 1 inch (25.4 mm) long. 7. The ink ejecting apparatus of claim 1, wherein the combined length of said manifold and said supply tube is in the range of approximately 3 to 4 inches (76.2 to 101.6 mm). 8. The ink ejecting device according to claim 1, wherein the manifold and the supply pipe have substantially the same area. 9. The ink ejecting device according to claim 1, wherein the reservoir section is arranged below the chamber section. 10. The ink ejecting apparatus according to claim 1, wherein the manifold has an inner wall with low followability.