DE2639697A1 - Uniform liq. pressure generator for ink jet printer - has flexible reservoir and pressure plate in liq.-tight housing - Google Patents

Abstract

A liquid in a flexible reservoir (3) is maintained under constant pressure such that as the reservoir empties via an outlet it is maintained in full condition by a pressure plate (6) acting on it. A spring-loaded lever (9) acts on the plate. The reservoir and the mechanical means n6, 8, 9, 14) for pressure production are contained in a housing (1) which is secure against outflow of the liquid. The lever (9) carries a reflective control unit (17) at a point furthest from its centre of rotation (10). Outside the housing a light transmitter and receiver is positioned opposite the reflector and is activated when the reflector is in a position corresponding to a min. liquid content in the reservoir. The unit is typically used in an ink jet printer.

Description

Device for generating a constant form

on a liquid in a reservoir The invention relates to a Device for generating a constant pressure on a liquid in a reservoir according to the preamble of claim 1.

In, for example, ink writing processes, it is necessary to use the To keep the pre-pressure in the ink almost the same in order to prevent the ink from leaking out to prevent the write head or BufQ entry into it. A constant Pre-pressure has an effect on the uniformity of the drop formation and thus on the imprint of characters It is also necessary to remove contamination from the leakage of ink during the transport of the writing unit, during its storage and in operation avoid. Furthermore, on the one hand, the remaining amount of ink in which is due to consumption emptying container as low as: n-'5 be able to avoid the loss of ink when replacing of the reservoir in the event that it is a disposable item, to keep it small. On the other hand, it must be prevented with certainty that air bubbles that form may have accumulated in the reservoir, not in the line leading to the write head be pressed, as these lead to a failure of the writing system. The two The latter requirements require the supply system to be switched off at a precise time.

In the DU-OS 23 23 762 is a device for generating a constant Pressure in a liquid has been described with a plate that has a bellows-like Reservoir against a plant presses. This is done on the reservoir Acting force generated by a spring force storage device, which is scissor-like between two arranged levers is unclamped and this tries to adjust swivel joints. As the container is emptied, the speed of rotation of the container increases Lever.

The bellows-like reservoir consists of a thin-var. 9 in itself deformable container which can be emptied by squeezing val in. However, there is the risk that during transport, storage and operation by improper handling and damage caused by ink crawling under the weld seams occur, so that ink can escape, which leads to contamination and thus to Loss ink leads. The plate acting on the reservoir becomes very slow moves, in addition, the pivoting movement of this slows down slightly as a result of the increasing ink cross-sectional area, so that the time of separation of the writing mechanism from the reservoir through a depending on the movement of the Plate-controlled switching element is not exactly determinable.

Accordingly, it is an object of the invention to provide the means for producing a constant form to be encapsulated from their surroundings.

This task is solved by the characteristics after the label of claim 1. In the further claims, preferred embodiments are shown.

By the invention it is achieved in an advantageous manner that the Ink supply unit sent separately and at the writing station in the writing unit can be installed. In the lever mechanism of the ink supply device was found a point that moves accelerating with increasing evacuation, so that the switching accuracy one depending on its Bewem controlled switching element when reaching a certain degree of emptying sufficient is high.

In the following, the invention is intended with reference back to the positions described in the drawing. A Querschmitt is shown in FIG by a device according to the invention and in Figure 2 a longitudinal section part of this device.

In the figures, a container 1 is shown, which is covered by a lid 2 is sealed liquid-tight. In the cover, which can be executed in a number of parts can, capillary chambers and channels 4 are let in to equalize the pressure in the increasing cavity when a reservoir 3 is emptied. In case that the reservoir is damaged and ink leaks into the cavity of the container 1, this is prevented from escaping from the container even if it is is in such a position that ink that has leaked out of the reservoir will damage the capillaries 4 reached.

The container 1 has a connecting piece 5 in a side wall part, glued to this and the reservoir 3 or connected by vulcanization can. The nozzle 5 is shown in the open position so that it is possible that Ink flows out of the reservoir 3. For transport and during storage the nozzle is kept closed. The reservoir 3 is opposed by a plate 6 the inner wall of the container 1 located. The plate is pivotable at 7 stored. In about the middle of its total length, an intermediate member 8 engages at one at 10 pivotably mounted lever 9 at 11 also is rotatably mounted. Between a hook attachment 12 on the lever 9 and a fixed container pin 13 is a tension spring 14 stretched, which the lever 3 clockwise tried to pan. The spring force is applied to the plate via the intermediate member 8 6 transferred, which is thereby pivoted counterclockwise.

The pivoting movement of the plate 6 is dependent on the ink withdrawal. If the withdrawal amount is set as a constant size, the plate swings around their fulcrum in slightly smaller angular units, since the cross-sectional area of the ink-filled cavity in the reservoir, line 15, also slightly coarser will. To describe the function, however, the same rotation paths of the plate are used 6 assumed; the increase in the cross section can be disregarded. Of the Path of the plate 6 is divided into the sections a, b, c, d, e. Will the plate 6 from the initial position to the second, marked by another division Moved position, the lever 9 moves to the distance a '. The same applies the other sections.

With constant emptying of the reservoir 3, the amounts that are deposited are proportionate Stretches a ', b', c ', d', and e 'increasingly gray. Along the way through the sections a '... e' running circular arc moves a point 16 of the lever 6. In this, an actuator 17 is attached to the lever part remote from the pivot point 10. On the outside wall a transducer 18 is attached to the container 1. The dash-dotted line in Figure 1 indicates its location. This is adjustable in such a way that the actuator 17 when moving into the end position, that is, when covering the partial distance e ', causes a change in the switching state of the transducer. The transducer can for example consist of a light emitting diode and a phototransistor while the actuator is designed as a mirror or mirrored surface part on the lever is. When the switch position is reached, the light emitted by the light-emitting diode is reflected on the phototransistor.

However, it is also possible to use an inductive transducer to be used with the piping core mounted on the lever 6 or a reed contact with permanent magnet attached to the lever, so that for the aforementioned Amwendur.gsfalls Breakthroughs for switch connections can be avoided, which are then again liquid-tight were too close. In individual cases when using photo optics, at least an area 19 may be transparent, which represents a beam path for passage of the rays to the phototransistor. It goes without saying that the device for generating pressure such as lever 9, intermediate link 8 and spring 14 with their respective suspension or pivot points must be present twice if they attack the edge area of the plate 6. However it is also possible to have only one system in the middle of the container and thus in the Attack the middle of the length of the plate 6.

L e r s e i t e

Claims (4)

Patent claims 1. Device for generating a constant Pre-pressure on a liquid in a reservoir, which in its volume when emptied adjusted to the respective fill level via an outlet from a movable plate is, with at least one loaded by spring force and rotatably mounted Lever acts on the plate, which increases as the reservoir empties As it rotates faster, there is no indication that the Re-Reservoir (3) and the means for generating pressure (6, 8, 9, 44) in a leak-proof container (1) are used that the lever (9) in an area remote from its pivot point (10) (16) carries an actuator (17) and the outside of the container and on its outer wall a transducer (18) which can be acted upon by the actuator is arranged in FIG a position in which it responds when the actuator is in the one minimum Corresponding position has been frozen. 2. Apparatus according to claim 1, d a d u r c h g e k e n n -z e i c h n e t that the transducer (18) consists of a light transmitter and a light receiver consists and the actuator (17) is a reflector that is in the beam path of the Light emitter outgoing rays can be moved in order to direct them to the light receiver reflect, at least the part of the wall (19) in the area of the opposite Members of the: Measured value pickup arrangement is designed to be translucent. 3. Apparatus according to claim 1, d a d u r c h g e k e n n -z e i c n e t that the transducer (18) is an inductive transmitter with on the lever (9) mounted iron core (16). 4. Apparatus according to claim 1, d a d u r c h g e k e. n -z e i c Note that the transducer (18) is a protective gas contact with on the lever (9) mounted permanent magnet (17).