JPS58191171A - Liquid-drop operation type printing mechanism - 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 In order to print, the present invention is provided with at least one nozzle arranged on a nozzle plate, from which printing liquid is discharged when necessary to the outlet of the nozzle. The present invention relates to a drop-operated printing mechanism which is carried onto a record carrier which is placed in front of an aperture.

Such a printing mechanism is known, for example, from Japanese Patent Laid-Open No. 52-4835. In printing mechanisms of this type, it often happens that the side of the nozzle plate facing the record carrier, and in particular located in the peripheral area of the nozzle, becomes wetted by the printing liquid leaking out of the nozzle. was. This has caused the disadvantage that paper dust from the recording paper adheres to the surface of the nozzle plate and forms a film that deteriorates the printing function with the printing liquid. It has the disadvantage that it occupies a portion and therefore the ejection direction of the droplets ejected to the outside is affected.

For example, by generating a constant negative pressure in the printing liquid system by means of a suction device, it is possible to prevent the printing liquid from leaking out of the nozzle. However, when the printing mechanism is stopped, its negative pressure becomes weaker, so that the printing liquid still leaks out.

The printing liquid container can also be made smaller compared to the nozzle plate, thereby creating a negative pressure within the printing liquid system to prevent printing liquid from leaking out of the nozzle. When the printing mechanism is stopped, the printing liquid present in the printing liquid system is sucked back into the printing liquid container. However, in this case, before printing, the printing liquid is sent from the printing liquid container to the nozzle, and then printing is performed, so when the printing mechanism is started, there is still enough time before printing is possible. The drawback is that there is a time delay.

The present invention prevents printing liquid from leaking out from the nozzle.
It is therefore an object to provide a drop-action printing mechanism of the kind mentioned at the outset, in which the side of the nozzle plate facing the record carrier is kept dry.

Such an object is achieved according to the invention by providing on the side of the nozzle plate facing the record carrier a membrane whose surface tension is lower than the surface tension of the printing liquid.

The liquid-repellent membrane deters the printing liquid so that it does not leak out from the nozzle. Furthermore, no paper dust is deposited on the nozzle plate, so that the ejection of the droplets is better achieved in a defined direction, and thus a high print quality is obtained.

By providing the membrane according to the invention on the nozzle plate, there is no need to create a negative pressure in the printing fluid system.

According to one embodiment of the invention, the membrane is cut obliquely d) in the region of the outlet opening of the nozzle. In this way, the interior of the nozzle is filled with printing liquid without the membrane having to cover the nozzle. be able to.

If all nozzles are not completely filled with printing liquid, the printing quality will deteriorate and the characters will not appear well.

According to another embodiment of the invention, the printing mechanism is provided with nozzles arranged in a row in a common nozzle plate for printing individual points, in front of the inlet openings of these nozzles. a contact piezoelectric transducer is arranged in such a way that changing the applied voltage at the contact causes the printing liquid to be expelled out of the nozzle and carried to a record carrier arranged in front of the exit opening of the nozzle; It is used as a droplet motion printing mechanism to record analog curves or alphabetic and numerical symbols and images in a dotted manner.

Next, the present invention will be explained in detail based on one embodiment shown in the drawings.

FIG. 2 clearly shows the basic structure of the known printing mechanism. Via the feed rollers 1, 2, a recording medium 3 (for example a conventional recording paper) is moved between the spacer 5 and the side surface 6 of the container 7 in the direction of the arrow 4.

A connecting conductor 8 is guided into the container 7, which is provided with a plug 9 at its free end, via which the
It is connected to a control mechanism (not shown) which provides control signals for recording the desired curve, image, etc.

FIG. 3 shows how the side surface 6 of the container 7 is arranged parallel to the record carrier 3. The side surface 6 of this container 7 is formed by the side surface of a nozzle plate 10 having a large number of nozzles 11 arranged in parallel in a row. In addition to the printing liquid, the container 7 contains a rod or transducer 12 made of piezoelectric material.
is provided. This rod or transducer 12 is contacted and arranged in such a way that it can be suitably electrically controlled to force the printing liquid out of the nozzle 11 in the form of droplets.

The transducer 12 is shaped like the teeth of a comb (see FIG. 4);
Operates as a bending vibrator. In that case, the piezoelectric comb consisting of the transducer 12 and the comb back 13 is arranged parallel to the plane of the nozzle plate 10. The free end region of the individual transducer 12 is placed in front of the individual nozzle 11 of the nozzle row. The back part 13 of the comb is fitted with a fixing screw 14. When a voltage is applied to the contacts of the transducer 12, the transducer 12 is displaced into the state shown in dotted lines in FIG. When the applied voltage is interrupted, the transducer quickly returns to its original, unbent position shown in solid line, and in doing so forces a drop of printing liquid through the nozzle 11.

The side surface 6 of the container 7 is shown in FIG. Thus, a membrane 15 having a surface tension smaller than that of the printing liquid is provided. The material of this membrane 15 is, for example, polyethylene or polytetrafluoroethylene. Membrane 1501μ
m~1' Op m s in particular has a thickness of 1 μm. In order to ensure that the entire nozzle 11 is completely filled with printing liquid, the membrane 15 covers the area 1 of the outlet opening of the nozzle 11.
6 is cut diagonally.

Since the surface tension of the membrane 15 is smaller than that of the printing liquid, the printing liquid does not leak out of the nozzle 11 and therefore into the container 7.
The sides 6 of are kept dry.

[Brief explanation of the drawing]

FIG. 1 is a sectional view taken along line II in FIG. 4 of a nozzle plate according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of the external appearance of a printing mechanism.
FIG. 3 is a partially sectional side view of a piezoelectric transducer operating as a bending vibrator, and FIG. 4 is a plan view of the comb-shaped piezoelectric transducer having the nozzle plate shown in FIG. 1. 3...Recording paper, 6...Side surface of nozzle plate, 10
... nozzle plate, 15 ... membrane, 16 ... area of the exit opening of the nozzle.

Claims (1)

[Claims] l) For printing, at least one nozzle arranged in the nozzle plate is provided, from which the printing liquid is discharged if necessary to the outside of the outlet opening of the nozzle. In a droplet action printing mechanism, a surface tension force is applied to the surface (6) of the nozzle plate (1o) facing the record carrier (3). A droplet operation type printing mechanism characterized in that 1 (15) is smaller than the surface tension of the printing liquid. 2) Droplet action printing mechanism according to claim 1, characterized in that said membrane (15) is made of polyethylene. 3) A droplet action printing mechanism according to claim 1, characterized in that said membrane (15) is made of polytetrafluoroethylene. 4) Droplet action printing according to any one of claims 1 to 3, characterized in that the membrane (15) has a thickness of 0.1 μm to 10 μm, in particular 171 m. mechanism. 5) said membrane (15) is located in the area of the exit opening of the nozzle (16);
5. A droplet motion printing mechanism according to any one of claims 1 to 4, characterized in that the portion ( ) is cut diagonally. 6) The printing mechanism is equipped with nozzles arranged in a row in a common nozzle plate for printing individual points, and contact piezoelectric transducers are arranged at the entrance openings of these nozzles. analog curves or alphabetic and numeric symbols, which are arranged in such a way that changing the applied voltage at the contacts causes the printing liquid to be expelled out of the nozzle and carried to the record carrier which is arranged in front of the exit opening of the nozzle. A droplet motion type printing mechanism according to any one of claims 1 to 5, characterized in that it is used as a droplet motion type printing mechanism for recording an image or the like in a dotted manner.