JPH023322A - Detecting device for residual quantity of ink in ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To enable detection of the exhaustion of ink at a time point when a very small residual quantity of ink is reached, by bending downward the force end part of at least one of electrode needles and by setting the fore end faces thereof at higher positions in stages than the position of an opening end of an ink supply tube. CONSTITUTION:An electrode needle 23 is bent in the shape of L in the part exposed in an ink tank 2, while the lower end thereof is set at a position somewhat higher than the lower end of an electrode needle 22. When an ink level lowers below a level A and further below a level B, a closed circuit between the electrode needle 23 and the ink supply tube 22 is broken and a circuit resistance being as low as several kilo-ohms theretofore changes to be as high as several mega-ohms. This change in the resistance is detected also by a resistance change detecting circuit and an ink exhaustion signal is generated therefrom. Based on this signal, a control element of an ink jet recording apparatus stops a recording operation and an operation of an ink supply pump while executing display of an alarm of the exhaustion of the ink etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a remaining ink amount detection device for an inkjet recording apparatus for detecting the amount of ink remaining in an ink tank that supplies ink to a recording head.

(Prior Art) In an inkjet recording device such as an inkjet printer, ink is supplied from an inkjet recording head equipped with a nozzle through an ink jet, and ink droplets are ejected from within the nozzle to perform recording. However, since the ink capacity of Infukacent is limited, it is necessary to replace the ink cassette when the ink cassette reaches a certain level or is used up.

In addition to visual observation, electrical detection means can be used to determine the amount of ink remaining in the ink tank of the ink cassette. An example of this electrical remaining ink amount detection device will be illustrated and explained.

FIG. 4 is a sectional view showing a conventional ink level detection device.

In Fig. 4, ■ is an ink cassette, 2 is an ink tank disposed in the ink cassette 1, 3 is ink stored in the ink tank, and a layer of air 4 is formed in the 2 part. There is ζ. Note that 2a is an ink tank welding part. 5 is a support member provided on the side wall surface of the ink tank 2; 6 is an electrode needle that is press-fitted into the support member 5 and is provided such that its tip is exposed inside the ink tank 2; and 7 is held upright by the support member 5. 8 is a camp member fitted into the head of the seal member 7; 9 is an ink supply tube inserted into the rear part of the seal member 7; 10 is an ink tube inserted into the head side of the seal member 7; It is a general-purpose hollow needle.

12 is a needle holder that supports the hollow needle 10; 12a is the hollow needle 1;
A conductive leaf spring 13 presses the electrode needle 6, and a conductive leaf spring 13 presses the electrode needle 6.

In the above configuration, a predetermined current is passed between the electrode needle 6 and the hollow needle 10, and the electrical resistance between the two electrodes is detected. This electrical resistance changes depending on the level of ink remaining in the ink tank 2. That is, when the ink level falls below the installation level of the electrode needles 6, the electrode needles 6 come into contact with air, and the resistance between the electrodes suddenly changes to a large value. Therefore, it is possible to know when to replace the ink cassette 1 by detecting this change in electrical resistance and turning on a warning lamp or the like.

The ink in the ink tank 2 is supplied to the inkjet recording head via a supply tube 9, a hollow needle 10, and an ink supply tube (not shown).

[Problem to be solved by the invention]

However, such conventional ink level detection devices have a configuration in which a straight tube-shaped electrode needle is inserted into the ink tank, so the detection level is considerably higher than the bottom of the tank, and the ink tank is actually There was an inconvenience in that an instruction to replace the ink cassette was issued even though there was a sufficient amount of ink remaining.

For this reason, users tend to replace the ink cassette according to the instructions (or warnings), or when recording even though they are aware that there is sufficient ink remaining, they may run out of ink midway. It continued.

Additionally, if printing continues until the ink in the tank runs out, the ink supply pump will operate even though the ink has run out, and when ink is ejected from the nozzle, the ink supply system will be filled with air, and then the ink will be discharged. When the liquid is supplied, air bubbles are generated, leading to abnormal discharge, which prevents normal recording.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink remaining amount detection device for an inkjet recording apparatus that can solve the problems of the prior art and can detect a small amount of ink remaining when detecting the remaining ink amount. .

[Means to solve the problem]

In the present invention, the open end of the ink supply tube is located near the bottom of the ink tank, and at least one of the electrode needles
The above object is achieved by bending the leading end of the book downward and placing the leading end surface at a stepwise higher position than the open end position of the ink supply tube.

In addition, in order to improve usability, a means is provided for the two electrode needles to issue a warning that the ink level is low, the ink supply pump is stopped, and the ink is running out each time the ink liquid level gradually decreases from the tip surfaces of the two electrode needles. Good.

[Effect]

With the above configuration, ink exhaustion is detected when the ink level falls below the electrode needle located closest to the bottom of the ink tank, and the open end of the ink supply tube is located near the bottom of the ink tank. In addition to this, it is possible to issue an ink-out warning when the amount of ink remaining becomes extremely low.

In addition, when the ink liquid level reaches a certain level, it is detected that the amount of ink remaining is low, and when the ink liquid level reaches an even lower level, the pump is stopped and the ink runs out.
Users can accurately understand ink usage status, and
No air bubbles are formed in the ink supply system, and no recording defects occur.

〔Example〕

The present invention will be specifically described below with reference to FIGS. 1 to 3.

FIG. 1 is a sectional view showing a remaining ink amount detection device according to the present invention. Note that in this embodiment, the same reference numerals are used for the same parts as in FIG. 4, so a redundant explanation will be omitted.

As shown in FIG. 1, the difference between this embodiment and the configuration shown in FIG. 4 is that instead of the electrode needle 6 and the ink supply tube 9, the tips of each are bent downward by approximately 90 degrees. In addition, an electrode needle 21 and an ink supply tube 22 are provided, and an electrode needle 23 is disposed above the ink supply tube 22.

The electrode needle 23 has a portion exposed in the ink tank 2 bent into an L-shape, and its lower end is positioned slightly higher than the lower end of the electrode needle 22.

In order to hold these electrode needles and ink supply tubes, the upper part of the support member 5 is extended, and the tip of each is supported by an L-shaped positioning member 25. Further, conductive leaf springs 13 and 24 are pressed into contact with the drawn-out ends of the electrode needles 21 and 23, and a connection is made to an external circuit (resistance change detection circuit) via these.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

When the ink in the ink tank 2 is at level A or higher, a closed circuit with sufficiently low resistance is formed between the electrode needles 21 and 23 via the ink liquid.

The electrical resistance in this closed circuit is, for example, several kilohms, and does not change until it reaches the level A.

As ink usage increases during recording or recovery operations,
The ink level in the ink tank eventually reaches level A. When the ink level further falls below the level A, the electrode needle 21 is completely separated from the ink, and only a portion of the tip of the electrode needle 23 is submerged in the ink. However, since the electrode needle 21 is floating above the ink, the electrode needles 21 and 2
3 is in an open state, and the resistance between the electrodes is as high as several megaohms. In this state, a closed circuit is formed between the electrode needle 23 and the ink supply tube 22.

This resistance change is detected by a resistance change detection circuit connected to the leaf springs 13 and 24, a low ink level warning signal is generated, and a low ink level warning is displayed based on this signal.

Next, when the ink level drops further below the level A and below the level B, the closed circuit between the electrode needle 23 and the ink supply tube 22 is broken, and until then the circuit resistance remains as low as a few kilohms. What was there changes to a height of several megaohms. This resistance change is similarly detected by a resistance change detection circuit and generates an ink out signal. Based on this signal, the control unit of the inkjet recording apparatus stops the recording operation and the operation of the ink supply pump, and displays a warning that the ink is running out.

FIG. 2 is a sectional view showing a second embodiment of the invention. This embodiment differs from the embodiment shown in FIG. 1 in that the tip of the ink supply tube 22 is shaped into an S-shape so that the tip contacts the bottom surface of the ink tank 2.

With such a configuration, the amount of ink remaining when ink exhaustion detection is performed can be significantly reduced.

FIG. 3 is a sectional view showing a third embodiment of the present invention. This embodiment is different from the embodiment shown in FIG. The extended tips of the electrode needle 23 and the ink supply tube 22 are positioned inside the tube.

With such a configuration, the amount of ink remaining when ink exhaustion detection is performed can be further reduced than in the configuration shown in FIG. 2.

〔Effect of the invention〕

As is clear from the above, according to the present invention, the open end of the ink supply tube is located near the bottom of the ink tank, and the tip of at least one of the electrode needles is bent downward, so that the tip surface of these tubes is bent downward. Since the ink supply tube 7-b is installed in stages at a higher position than the opening end position, it is possible to detect ink shortage when an extremely small amount of ink remains. Therefore, it is possible to accurately know when to replace the ink container and gutter, and to improve usability.

In addition, when the ink liquid level reaches a certain level, it is detected that the amount of ink remaining is low, and when the ink liquid level reaches an even lower level, the pump is stopped and the ink runs out.
In addition to being able to accurately grasp the ink usage status, the generation of bubbles in the ink supply system is prevented, and normal ink ejection can be performed at all times.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view showing a second embodiment of the invention, FIG. 3 is a sectional view showing a third embodiment of the invention, and FIG. 1 is a sectional view showing a conventional ink level detection device. 2--------- Ink tank, 3・---------
-Ink liquid, 21.23---One electrode needle, 22.
−−−−−−−−−Ink supply tube @

Claims (2)

[Claims] (1) An ink tank filled with ink liquid, an ink supply tube attached to the lower part of the side wall to guide the ink liquid in the ink tank to the outside, and an ink supply tube arranged at the upper part of the ink supply tube with a predetermined length. The remaining amount of ink of an inkjet recording device, which is equipped with at least one electrode needle exposed in a tank, and detects the remaining amount of ink by changing the electrical resistance of the electrode needle and the ink supply tube according to the ink liquid level. In the detection device, the open end of the ink supply tube is located near the bottom surface of the ink tank, and the tip of at least one of the electrode needles is bent downward, so that the tip surface of the electrode needle is positioned near the bottom of the ink tank. An ink remaining amount detection device for an inkjet recording device, characterized in that it is installed at a stepwise higher position. (2) When there are two electrode needles, it is detected that the ink liquid level is below the tip surface of the first electrode needle, and a warning is given that the ink level is low; 2. The ink remaining amount detecting device for an ink jet recording apparatus according to claim 1, further comprising means for detecting that the ink is below the tip of the needle and stopping the ink supply pump and for warning of ink shortage.