DE19704969C1 - Ink jet printing head for office printer - Google Patents

Abstract

The printing head is reciprocated in the ink ejection direction via a rotary or linear movement. Each of the ink feed channels (13) for each of the ink chambers (14) is supplied via a common ink feed (12) with an ink entry (111) selectively closed at its narrowest point by a sliding valve (2). The valve has a linearly displaced valve plate (21) with a flow aperture (211) which is brought into alignment with the ink entry and which has a reduced flow volume relative to the volume play for the ink columns of the jet channels (15).

Description

The invention relates to an ink print head, the temporarily accelerated rotary movements and / or linear movements is exposed in and opposite to the ink ejection direction.

Ink printheads are mainly used in office printers. In these devices alternate between the record carrier and the Ink printhead moves in orthogonal directions to each other, whereby the distance between the two is constant. The movement of the ink printhead is usually transverse to the direction of ink ejection or parallel to the record carrier level. This is also the case when the ink printhead runs in certain print pauses  nigt and / or sealed. The ink printhead becomes this Purpose in a cleaning and sealing position outside of the Print position moved and remains in this position during a Cleaning and sealing station moved up to it and docked becomes.

For some years now, however, there have been new areas of application for tin tapped printheads, such as product labeling devices, franking machines and reproduction equipment with signature.

The movement sequences differ from those in the Office printer. While the line of the usual office printer done wisely, it is quick for franking machines Throughput required that the print as a one-time franking printing takes place in one pass of the postal matter.

For hand franking machines and some product labeling devices the record carrier is at rest and only the printer becomes relative moved to the record carrier.

Both not only require a larger number of nozzles accordingly the printing width, but also changed, adjusted accordingly Processes for cleaning and sealing and, if necessary, for Thickness compensation of the postal matter.

In a known arrangement, compare DE 36 08 912 C2, the ink print head from a working position to a cleaning position or in a rest position with sealing turned and in or shifted against the direction of ink ejection.

With accelerated movement there is a risk that ink is thrown out unintentionally or that at counter set direction of movement the ink printhead draws air and therefore follow the ink meniscus tears. Due to the capillary action only barrier pressures between 5 and 50 millibars are available.

The former has ink losses and harmful soiling The consequence and the latter can lead to malfunctions of the ink print head to lead.

It is also an arrangement for an ink print head in Piezoplanar technology known, see DE 295 21 128 U1, in the plates are stacked one on top of the other, into the ink supply channels, inks  pressure chambers, nozzle channels and nozzle openings are formed. The ink supply channels are shared by one Supply channel fed.

On the other hand, there is an ink-jet device with an up along one Drawing carrier movable ink print head known in which the inks flow area to the ink print head is designed closable, compare che DE 25 39 983 B2.

In particular, there is a valve chamber with inflow lines from one Reservoir and with a drain line to the ink pressure came flow connection. One is at rest in the valve chamber location fluid-tight coil spring arranged with one end slipped over the drain pipe and free with her oscillating end through a trained as a vibrating mass Stopper is complete.

When the ink print head is at rest, the turns of the Coil spring so close together that no ink from the foreground storage container via the supply lines and via the valve chamber to the Ink printhead can flow.

If the ink print head is moved along the record carrier, then the coil spring swings through on the ink print head acting acceleration forces constantly. This is the spring turns are lifted from each other so that ink can flow.

Accordingly, when the ink print head moves, a unwanted ink leakage or mini-tear with this solution does not preventable. Add to that the valve in the form of the screws spring with stopper is not volume neutral.

Finally, there is a distributor with a tubular slide valve for an inkjet printhead - continuous flow ink jet printer - known, see IBM Technical Disclosure Bulletin Vol. 22, No. March 10 1980, page 4409.

The tubular slide valve is so displaced in the manifold bar that three positions are possible:

First, a print mode in which the valve opening with an ink inflow line is connected by a pump.

Second, a transition mode, in which the valve opening by a Sealing ring is sealed.  

Third, a suction mode in which the valve opening with a Drain channel is connected to a collecting container.

This solution is specially designed for continuous inkjet printing provided head and not due to the tubular design volume-neutral.

The purpose of the invention is to improve the utility's own , in particular an enlargement of the area of application and of reliability.

The invention has for its object a device to create an unwanted ink escapes and effectively prevents mini-tear.

The device is intended for both an ink print head in one piece compact design as well as for one of several ink printing existing module print head can be used. It should Modules of all possible principles - edge shooter, sideshooter, back shooter - be allowed.

According to the invention, this object is achieved by the ink flow area at the point with the smallest wire cross-section Slide valve made of an extremely thin blade with a flow opening and an associated drive for adjusting the blade is arranged. The volume of the flow opening is smaller dimensioned as the permissible volume play for the ink columns in the Nozzle channels.

This shutter is used during the rotary or linear movements activated.

By interrupting ink flow and pressure equalization, becomes a quasi-closed system with low compressibility of the Print medium formed and consequently the ink in the nozzle channels and subsequent ink pressure chambers, ink channels and in common supply channel kept very effective.  

The arrangement of a slide valve at the point with the smallest Cable cross-section enables a closure without displacement volume to achieve.

The slide valve can both inside and outside the common supply channel can be arranged. That would open different possibilities for its control. On in any case, the shutter is as close as possible to the ink printhead so that the volume of ink to be held is minimal.

The invention is explained in more detail below using the exemplary embodiment explained.

The figure shows a schematic diagram of the device according to the invention.

The illustration is for simplification and easier understanding carried out schematically.

Referring to FIG. 1, an inkjet printing module 1 one after another in a direction of ink common supply channel 12, Tintenversor supply channels 13, ink pressure chambers 14 and opening out to the outside nozzle channels 15.

The common supply channel 12 is fed via an ink port 11 with an opening 111 . At the ink port 11 , a hose is connected, not shown, which leads to an ink tank.

A slide valve 2 is arranged in the common supply channel 12 immediately before the opening 111 . The slide valve 2 consists of an extremely thin blade 21 with a flow opening 211 adapted to the opening 111 and an associated drive 22 .

The blade 21 is slidably arranged between the rear wall of the common supply channel 12 and guide elements 23 . In the position shown, the ink flow is open. The blocking takes place by moving the blade 21 sideways by more than one diameter length of the opening 111 .

If the blade 21 is only partially displaced, the fluidic impedance of the entire ink line in the ink printing module is increased; this can be of interest for impedance matching of barcode printers.

Such adjustments may be necessary when changing ink - Change in viscosity - or adjustment of ink droplet size.

Reference list

1

Ink print head or ink print module

11

Ink connection

111

Ink port opening

11

12th

common supply channel

13

Ink supply channel

14

Ink pressure chamber

15

Nozzle channel or nozzle

2nd

Slide valve

21

Blade of the slide valve

2nd

211

Flow opening of the blade

21

22

Drive for the blade

21

23

Blade guide

21

Claims (3)

1.Ink printhead which is temporarily subjected to rotary movements and / or linear movements in and opposite to the ink ejection direction and which is optionally designed in a compact design or composed of individual modules and whose ink supply channels ( 13 ) are fed to the ink pressure chambers ( 14 ) via common supply channels, whose ink inflow area ( 111 ) is designed closable by in the ink inflow area ( 111 ) at the point with the smallest line cross-section a flat slide valve ( 2 ) made of an extremely thin blade ( 21 ) with a flow opening ( 211 ) and an associated drive ( 22 ) is arranged for adjusting the blade ( 21 ), the volume of the flow opening ( 211 ) being dimensioned smaller than the permissible volume play for the ink columns in the nozzle channels ( 15 ). 2. Device according to claim 1, characterized in that the slide valve ( 2 ) is arranged within the common supply channel ( 12 ). 3. Apparatus according to claim 1, characterized in that the slide valve ( 2 ) outside the common supply channel ( 12 ) is arranged in an ink port ( 11 ).