JPS586420A - Detector for residual quantity of ink - Google Patents

Abstract

PURPOSE:To obtain a titled detector which is available even to the ink having a low level of surface tension with a small and simple structure, by setting a detecting terminal to be attached to the inside of a tank at the head of a column. CONSTITUTION:A detecting terminal to be attached to the inside of a tank is set at the head of a column. For instance, an attachment part 13 composed of a material having <=30dyn/cm critical surface tension is formed into a column with two steps, and a detecting part of a detecting terminal 12 is set at the head part of the column. When the residual quantity of ink is reduced down to the position of a line 14, the ink is raised above a surface 16. The ink is still left at an edge 15 to keep the conduction with the terminal 12. When the ink is less reduced down to the position of a line 19, the quantity of ink of the surface 18 is decresed. Then the ink runs out at the edge 15 by the force of the surface tension. Thus the terminal 12 is insulated, and the residual quantity of ink is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a remaining ink amount detector used in an inkjet printer.

Inkjet printers are a technology that is becoming popular for several reasons, including low annual noise and fairly high printing speeds. In addition, the method of detecting the remaining amount of Inter-O by changing the impedance is a generally convenient and used technique because of its simple mechanism and low cost. There is a standard. That is, the electrical resistance is relatively small, and the surface tension is at least sO complex. There is no need to explain the electrical resistance, but the reason why a small surface tension becomes an obstacle will be explained in conjunction with jlllU. If the ink enters the ink intake port 2 in the inter-tank 1, the ink may flow through the inter-flow path 3 in the cartridge. It is guided to the pressure chamber 4 and the nozzle 5 also ejects in the form of small droplets. Printing is performed by this operation, but if the remaining amount of ink in the intertank 1 is at the line 60 position, the detection terminal 7 attached to the intatank 1 is submerged in ink, so it will not be hit. It is in electrical conduction with the detection terminal port attached to the ν. Therefore, the resistance meter t
indicates a low value, when the ink level is used and the remaining ink level is line 1.
When the value is reduced to the 0 position, the detection terminal 8 remains submerged in the ink, but the detection terminal 7 is exposed to the air, and the two detection terminals are insulated and the resistance meter 9 shows a high value. The basic principle of detection is as described above, but let us now assume that the surface tension of the ink has become considerably small.

The reason why you want to use ink with low surface tension is that in the past, when using paper for quick-drying printing, surfactants were added to the ink to reduce the surface tension of the ink to make it absorb into the paper faster. This is because it is necessary to lower the ink to about 50 dyn/II, but in that case the remaining ink level is 111
Even if the voltage is reduced to the 0 position, the bottom surface 11 of the tank 1 is evenly wetted with ink, and even though there is only a small amount of ink remaining, the two detection terminals are electrically connected.In that case, the resistance meter 9 naturally becomes This results in a low value.

Therefore, remaining amount detection using changes in impedance cannot be used for ink with low surface tension.

The present invention aims to eliminate such drawbacks. This will be explained below with reference to FIG.

FIG. 2 differs from the conventional example shown in FIG. 1 only in the manner in which the detection terminal 12 on the tank side is attached and the material of the attachment portion 13. The mounting part 13 has a two-stage cylindrical shape, and the detection terminal 12 is attached to the column head.
A detection unit is arranged.

The operation will be explained by enlarging only the capital portion in FIG. 3. First, when the remaining amount of ink decreases to the position of the line 14, the second columnar surface 16
The ink remaining on the top forms a dot-line shape. In this state, since the amount of ink below the second capital surface is abundant, a large amount of ink is pulled up onto the surface 16 due to surface tension, and the ink has not yet run out at the edge 15. Therefore, electrical continuity between the terminal 12 and the ink is maintained. When the ink further decreases and reaches the position J119, the ink takes on the shape of a solid line. In this case, the ink does not run out at the edge 17 for the same reason as mentioned above. However, the amount of ink on the first capital surface 18 is reduced, and the ink is pulled against each other due to surface tension between the first capital surface 18 and the second capital surface 16, and as a result, the ink runs out at the edge 15. I end up. The diameter of the second cylinder is 21 and the diameter of the first cylinder is 22I2! and the height of each cylinder are dimensions that depend on the diameter 20 of the detection terminal, the surface tension of the ink, and the material of the mounting part 15. Generally, the larger the size, the higher the safety factor, but the minimum practical dimension is It is easy to obtain by experiment. By the way, each of the above-mentioned dimensions can be designed to be smaller by using a material for the mounting portion 15 that has poor wettability with water. Specifically, critical surface tension cuffs such as fluororesin, silicone resin, polyethylene, and polypropylene are used.
Each dimension can be made smaller by using a material with c less than S Odyn/aw.

As an example, the diameter of the first cylinder is =φ2-6mm,
Height hl: [15m, diameter of second cylinder "*"lItBm,
Height, = 1.5cm, diameter of detection terminal, = φ1, material is polyethylene, surface tension of ink is 32117n15
It is +.

Incidentally, if it is acceptable for the dimensions to become somewhat larger, it can be implemented by increasing the height h of the one-stage cylinder instead of using a two-stage cylinder.

As described above, according to the present invention, it is possible to detect the remaining amount of ink using a change in impedance with a small and simple structure and a low surface tension ink.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing a conventional ink level detector. FIG. 2 is a schematic cross-sectional view showing the remaining ink amount detector according to the present invention. FIG. 3 is a schematic cross-sectional view showing the shape of the detection part according to the present invention. Attorney Mogami Patent Attorney Written amendment to legal proceedings (Volunteer 1, IO 2, 1980, Mr. Commissioner of the Japan Patent Office ■, Small case indication 1981 Patent Application No. 1 o E 1 qo No. 2, Name of invention Ink level detector 3, Amendment Figure 2: 111 people related to the incident

Claims (1)

[Scope of Claims] (1) A remaining ink amount detector in a method of detecting remaining ink amount using impedance change, characterized in that a detection terminal is arranged at the capital of a cylinder. (2) The remaining ink amount detector according to claim 1, wherein the detection terminal is arranged at the capital of the two-stage cylinder. (8) The material of the cylinder has a critical surface tension ro of 30dy.
The remaining ink amount detector according to claims 1 and 2, characterized in that it is an insulator of 11/w or less.