JPH0664140A - Device for preventing ink shortage in printing process - Google Patents

Abstract

PURPOSE:To prevent defective printing due to an ink shortage in screen printing. CONSTITUTION:In the case a screen as a printing plate and a squeegee sliding on the screen are provided in a screen printer and an ink reservior is formed between the front face of squeegee and the plate during the operation, at least one sensing nozzle 12 installed on the front face of the squeegee 3, a device 10 feeding pressurized fluid to the sensing nozzle and an alarm device working in response to the end of the sensing nozzle 12 protruding out of the ink reservoir 4 are provided in the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink out prevention device in a screen printing process.

[0002]

2. Description of the Related Art As is well known as screen printing, a screen such as a gauze is put on a frame, and the image is usually made by photographic means with the outer part of the screen being blinded as a plate, and then squeegeeed through the screen. Refers to the method of printing by extruding ink.

The squeegee used for screen printing is formed by sandwiching an elongated rubber plate between holders made of wood or metal.
By pressing and sliding on the screen, the ink contained in the mold is extruded into the printing medium from the screen eyes of the image area to print. The angle formed between the tip of the rubber plate and the screen, the hardness of the rubber, the sliding speed, the pressure, etc. affect the extrusion amount of the ink. In the steady printing state, the height between the squeegee tip and the screen is, for example, about 2
Create a cm ink fountain.

[0004]

In the above-mentioned screen printing, when the ink supply amount is insufficient with respect to the ink consumption amount, the ink pool in front of the squeegee decreases and finally becomes zero, causing ink shortage. Occurs, resulting in defective printing. At present, the machine is stopped after the ink runs out, the ink supply amount is increased, and the machine is started. However, this method produces a large amount of defective products.

An object of the present invention is to eliminate the above-mentioned drawbacks, to provide a method and an apparatus for preventing ink shortage in screen printing, and to generate an alarm or the like before the ink shortage actually occurs to prevent the generation of defective products. is there.

[0006]

The outline of the present invention for attaining the above-mentioned object is to detect a decrease in the liquid level of an ink fountain formed on the front surface of a squeegee before the actual ink shortage occurs. The alarm device is activated to prevent the generation of defective products due to ink shortage.

According to the embodiment of the present invention, an air pressure of about 1 to 2 mm of water is applied to the tip of the detection nozzle using a fine level switch of the air pressure sensor type, and the detection nozzle is attached to the squeegee to reach the required depth. Put in the ink fountain. If the liquid level in the ink reservoir drops and the tip of the detection nozzle is opened, the switch is activated and the alarm device is activated. As a result, the alarm device is automatically activated when the level of the ink fountain is lowered, and it is possible to take necessary measures before the ink runs out.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments exemplifying the present invention and drawings will be described. FIG. 1 shows an outline of the present invention. A squeegee 3 slides on a screen plate 2 on a frame 1 on a substrate (not shown) by a sliding mechanism (not shown). Ink squeegee 3 with a height of approx.
Is formed.

According to the present invention, two detection nozzles 12 of the fine level switch 10 are attached to the front surface of the squeegee 3, and the tip of the detection nozzle 12 is embedded in the ink reservoir 4 for several millimeters. A required signal is generated while both detection nozzles 12 are inside the ink fountain 4, and an alarm signal is generated when at least one of the detection nozzles 12 is outside the ink fountain 4. The fine level switch has a pressure of 0.1 to 0.3 kg / cm ² and a fluid P. P.S. The I port 18 is connected to the detection nozzle 12 to supply a pressurized fluid having a water column of 1 to 3 mm to the tip of the nozzle 12.

FIG. 2 shows an air pressure circuit of the fine level switch 10. The pressurized air source 14 passes through a pressure regulator 20, an air filter 22, a micro aleser 24, and a precision pressure regulator 26, and the pressure is 0.1 to 0.3 kg. / Cm ² of pressurized air to the fine level switch 10 P. Supply to the S port 16. P. Detection nozzle 12 from I port 18 via conduit
The pressurized air is sent as a water column of about 1 to 3 mm. Since the ink is viscous, the moment when the tip of the detection nozzle 12 leaves the ink reservoir 4 is accurately detected.

That is, when the tip of the detection nozzle 12 is in the ink, there is conduction between the COM and NO contacts of the micro switch of the fine level switch 10. When one or both detection nozzles 12 come out of the ink reservoir 4, the COM and NO contacts of the micro switch are in emergency communication. This on
Off is used to activate the alarm circuit to detect a drop in the level of the ink fountain 4 and inform the operator that the ink supply should be increased before ink runs out. Although the above-described configuration detects the level drop of the ink fountain 4 using the air pressure, other level drop detection means may be used.

[0012]

As has been made clear by the present invention, by detecting the lowered level of the ink fountain formed before the squeegee of screen printing according to the present invention, an alarm signal can be received before the actual ink out occurs. Solved the problem of defective products due to running out of ink.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an ink out prevention device in a screen printing process according to an embodiment of the present invention.

FIG. 2 is a fluid circuit diagram of a fine level switch used in the apparatus of FIG.

[Explanation of symbols]

 1 frame 2 screen version 3 squeegee 4 ink reservoir 10 fine level switch 12 detection nozzle 14 pressurized air source 16 P. S-port 18 P.S. I port 20 Pressure regulator 22 Air filter 24 Micro alescer 26 Precision pressure regulator

Claims (1)

[Claims] 1. A screen printing machine is provided with a screen as a printing plate and a squeegee that slides on the screen, and when an ink pool is formed between the front face of the squeegee and the plate during operation, the front face of the squeegee 3 is formed. At least one detection nozzle 12 attached to the device, a device 10 for supplying a pressurized fluid to the detection nozzle, and a tip of the detection nozzle 12 at the ink reservoir 4
A device for preventing ink depletion in a printing process, comprising: an alarm device that operates in response to the ink coming out of the inside.