JPH0463780B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an ink remaining amount detection device, particularly an ink supply path provided between a storage section holding ink and a print head to which ink is supplied from the storage section. The present invention relates to a remaining ink amount detection device that detects the amount of ink remaining in the storage section.

BACKGROUND ART In recent years, inkjet printers that record images, characters, etc. on a recording medium by ejecting ink from fine nozzles have become popular. This type of printer does not use an ink ribbon, but uses the ejection mechanism of the print head, which is connected to the ink tank through a tube, to eject liquid ink stored in an ink tank onto a recording medium such as paper as fine droplets. Recording is carried out by flying it. Therefore, unlike ink ribbon printers, inkjet printers are usually equipped with a mechanism to detect the amount of ink remaining in the ink tank in order to prevent printing defects due to running out of ink. When the ink tank became insufficient, a warning sound was emitted to prompt the user to replenish the ink or replace the cartridge-type ink tank.

Conventionally, various methods have been used to detect the remaining amount of closed ink tanks, such as an ink head detection method and an ink tank weight detection method using a strain gauge.However, the water head detection method uses a flat (horizontal) flexible method. In addition, the weight detection method has the disadvantage of being susceptible to drops and vibrations.

FIG. 1 shows an example of a remaining ink amount detection mechanism of a conventional inkjet printer. In FIG. 1, a bag-shaped ink tank 1 made of a flexible material is housed in a case 2 provided with a vent. The ink in this ink tank is supplied from a needle-shaped pipe 3 to a supply tube 5. A pressure detector 4 using a semiconductor sensor or the like is provided between the pipe 3 and the supply tube 5, and this pressure detector 4 is provided between the pipe 3 and the supply tube 5. The liquid level of the ink is detected using a device. In such a water head detection type remaining amount detection device, since the ink tank is arranged vertically in order to improve detection accuracy, there is a drawback that the ink level fluctuates greatly, which has a large effect on the pressure in the supply path.

It is also possible to consider a method in which a liquid pressure detection means is provided in the supply path between the ink tank and the recording head to constantly monitor pressure changes in the ink supply path. There is a problem that detection accuracy is low because it is easily affected by vibrations of the recording head and air bubbles generated in the supply path.

In addition, if pressure changes in the ink supply path are constantly monitored during printing, there is a high possibility that the time when no ink is detected is during the printing period, which means that a failure such as running out of ink will occur during printing. The problem is that this possibility is extremely high.

Purpose The present invention has been made in view of the above problems, and it is an object of the present invention to provide an ink level detection device that can reliably detect the level of ink remaining in an ink tank with a simple and inexpensive structure. do.

In order to achieve the above object, the ink remaining amount detection device of the present invention is provided in an ink supply path between a storage section holding ink and a print head to which ink is supplied from the storage section. In the device for detecting the amount of ink remaining in the storage section, a configuration is adopted that includes means for determining the amount of ink remaining in the storage section based on a pressure change occurring in the ink supply path after the suction operation of the suction means acting on the print head.

Embodiments Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. However, in each of the following drawings, the same reference numerals are given to the same or corresponding parts as in the conventional example, and the explanation thereof will be omitted.

FIG. 2 shows a schematic diagram of the inkjet printer of the present invention. In FIG. 2, the reference numeral 7 indicates an inkjet head 7, which is equipped with an ink ejection mechanism using a piezoelectric element (not shown), and is connected to a flexible inkjet head 7 housed in the case 2 via an ink supply path 5. It is combined with the sexual ink tank 1.

In normal inkjet printers, air bubbles may form in the ink supply path due to the initial filling of ink into the ink supply path and ink jet head 7 immediately after replacing the cartridge type ink tank, or due to long periods of non-use. Ink suction mechanisms 8, 9, and 10 are provided for recovery in case of solidification.
This is because in an inkjet printer, the ink passage from the ink tank to the print head must always be filled with ink without any air bubbles being mixed in. The recovery or initial filling device described above is set to be driven at various times, such as when the power is turned on or at a predetermined timing during printing.

The suction mechanism illustrated here is one that is placed outside the printing area or on the head carriage.
The capping 8 seals the tip of the inkjet head 7, and the suction device 1 is connected via the tube 9.
By applying a relatively large negative pressure at 0 to perform ink suction, ink is sucked out, bubbles, coagulated matter, dust, etc. are removed, or the ink jet head 7 is initially filled with ink.

In the present invention, the amount of ink remaining in the ink tank 1 is detected by detecting the state of negative pressure in the ink supply path 5 during the recovery operation or the initial filling operation. For this purpose, as shown in FIG. 2, a pressure detector 4 using a semiconductor sensor or the like is provided in the middle of the ink supply path 5. This pressure detector 4 is connected to an alarm unit 13 such as a buzzer, and is configured to issue a warning when the remaining amount of ink falls below a predetermined level.

The pressure detection timing of this pressure detector is determined in conjunction with the pressure feeding operation (suction operation) of the suction device 10. That is, the detection operation of the pressure detector is performed in conjunction with the on/off of the switch 11 for driving the suction device 10, and the detection timing is delayed by the delay circuit 12.

Figure 3 shows the timing of pressure detection. During the suction operation during initial filling or recovery, the discharge port of the ink jet head 7 is sealed by the capping 8 by a drive means (not shown), and then, at time t0, the suction device 10 is driven via the switch 11. .

Next, from time t0 to t1, a delay is performed by a predetermined time delay circuit 14, and from t2 to t3, the pressure in the ink supply path 5 is detected by the pressure detector 4. The delay time at this time is determined by the flow path resistance in the ink supply path 5 and the ink jet head 7, etc.

The reason why pressure detection is performed with such a delay is because ink suction is performed using a relatively large negative pressure in a recovery device that performs suction using a suction mechanism outside the ink jet head 7, such as in this embodiment. This is because it must be done. This is because, in the present invention, pressure detection for detecting the remaining amount of ink is performed in a small negative pressure region close to atmospheric pressure, as will be described later. This is because the negative pressure is determined only by the negative pressure generated by the suction device 10. Therefore, the delay circuit 14 can be omitted in an inkjet printer in which a recovery pressure feeding device such as a tube pump that generates a relatively weak negative pressure is provided between the ink tank 1 and the inkjet head 7.

FIG. 4 shows the negative pressure state in the ink supply path 5 corresponding to the remaining amount of ink in the ink tank 1. In FIG. 4, as shown by detection curves A and B, the pressure in the ink supply path 5 gradually increases from a large negative pressure region (approximately -9 m Ag) immediately after the operation of the suction device 10 over a period of time corresponding to the flow path resistance. The pressure will recover to near atmospheric pressure.

If there is sufficient ink in the ink tank 1, the negative pressure in the ink supply path 5 is at a certain empty level at time t2, as shown by symbol A.
Returns to a higher pressure than PE. This is because the ink tank 1 is made of a flexible material, and when it contains enough ink, the ink tank 1 deforms smoothly in the direction of collapse, allowing ink to flow into the ink supply path 5 without resistance. It is.

When the amount of ink remaining in ink tank 1 decreases,
It takes longer and longer time for the pressure in the ink supply path 5 to recover, and when almost all ink is used up, the predetermined empty level PE is reached at time t2, as indicated by reference numeral B.

This is because the deformation of the ink tank 1 described above cannot be performed smoothly, and the ink cannot be smoothly supplied into the ink supply path 5. Therefore, a predetermined empty level PE is determined according to the remaining amount of ink to be detected, and the negative pressure in the ink supply path 5A reaches the empty level at time t2.
If the alarm unit 13 is configured to be activated when the PE is broken, it will be possible to accurately notify that the amount of ink remaining in the ink tank is low.
It is possible to prompt the replacement of the ink tank 1. Alternatively, the alarm unit 13 may be operated by detecting the rate of change in negative pressure using a calculation means or the like by utilizing the effect that a change in the deformation rate of the ink tank 1 has on a change in negative pressure. An example of this alarm timing is illustrated in the bottom row of FIG. 3.

According to the embodiment described above, it is only necessary to provide a pressure detector and a delay circuit in addition to the pressure feeding (suction) device for recovery, etc., which is essential for inkjet printers, so the remaining amount can be ensured with a simple and inexpensive configuration. Detection can be performed.

Effects As is clear from the above explanation, the remaining ink level detection device according to the present invention can be used at the time of initial filling, periodically,
Alternatively, in a print head recovery operation performed in the event of an ink ejection failure, etc., the remaining amount of ink in the reservoir is determined based on the pressure change that occurs in the ink supply path after the suction operation of the suction means acting on the print head.

Therefore, when the negative pressure forcibly generated in the ink supply path in response to the suction operation of the suction means returns to atmospheric pressure, the pressure in the ink supply path decreases as the remaining amount of ink decreases within a large pressure change range. Because it detects changes, it is not affected by minute pressure fluctuations that may occur in the ink supply path, and has extremely high accuracy compared to methods that constantly monitor minute pressure changes in the ink supply path, for example. You can determine the amount of ink remaining.

Furthermore, in the present invention, in order to utilize the pressure change caused by the suction operation of the suction means to detect the remaining amount of ink,
Rather than constantly monitoring minute pressure changes in the ink supply path, the remaining amount can be detected during a period separate from the printing operation. Therefore, the user can know whether or not there is a sufficient amount of ink in the ink tank at the time of initial filling of the print head with ink, and the possibility of running out of ink during printing can be significantly reduced.

In addition, since the pressure change caused by the suction operation of the suction means is used to detect the amount of ink remaining, the remaining amount is detected after removing air bubbles in the supply path that have an adverse effect.In this sense, too, the detection accuracy is increases. Further, during the recovery operation, it is possible to know whether or not the cause of the ejection failure is due to a decrease in the remaining amount of ink, which has the excellent effect of improving operability.

In any case, the present invention is a method for detecting pressure changes when a larger amount of ink is moved than the amount of ink supplied and moved during normal recording, so it is a method for detecting pressure changes due to ink during normal printing. Compared to this, it is more reliable and can prevent malfunctions in detecting the amount of remaining ink. Specifically, since it is possible to clarify whether the amount of ink remaining in the ink tank is appropriate for recording by moving a large amount of ink, there is an effect with excellent relativity.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a conventional ink level detection mechanism.
FIG. 2 is a block diagram showing the configuration of the printing device of the present invention, FIG. 3 is a timing chart showing the pressure detection timing in the present invention, and FIG. 4 is a diagram explaining the principle of ink remaining amount detection in the present invention. It is. 1... Ink tank, 4... Pressure detector, 5
A, 5B... Ink supply path, 7... Ink jet head, 8... Capping, 10... Suction device, 11... Switch, 12... Delay circuit, 13
...Warning department.

Claims (1)

[Scope of Claims] 1. A device for detecting the amount of remaining ink provided in an ink supply path between a storage section holding ink and a print head to which ink is supplied from the storage section, which acts on the print head. An ink remaining amount detection device comprising means for determining the remaining amount of ink in the storage section based on a pressure change occurring in the ink supply path after the suction operation of the suction means. 2. Remaining ink amount detection according to claim 1, wherein the determining means detects the amount of ink remaining in the reservoir according to the result of comparing the pressure change with a predetermined reference. Device. 3. Claim 1, wherein the determining means detects the amount of ink remaining in the reservoir according to the result of calculating the rate of change of the pressure change.
The remaining ink level detection device described in . 4. According to any one of claims 1 to 3, the discrimination means includes a delay circuit that delays the detection timing of the pressure change by a predetermined period with respect to the suction operation of the suction means. The remaining ink level detection device described. 5. Claims 1 to 4, wherein the determination means includes notification means for prompting replacement of the storage section provided in the inkjet recording device by notifying a decrease in the amount of ink remaining in the storage section. The remaining ink amount detection device according to any one of the preceding items.