JPS6249189B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet recording apparatus using an inkjet recording method in which ink fed from an ink tank storing ink is atomized and jetted toward a recording medium.

The inkjet recording method records characters, figures, etc. by causing small droplets of ink to fly towards the recording medium and deposit them on the recording medium in a predetermined information pattern, and is a low-noise recording method.
It is attracting attention as a very useful recording method because it allows plain paper recording and high-speed recording. As shown in Japanese Patent Publication No. 53-12138, an inkjet recording device used in this recording method has conventionally used the displacement of a vibrator driven by an electric signal to eject ink from an inkjet recording head. 2. Description of the Related Art An inkjet recording apparatus is known that has a structure in which the chamber volume is changed and ink droplets are ejected from an orifice in response to the increase/decrease operation of the ink chamber volume.
This inkjet recording apparatus will be explained below. An ink pressurizing chamber filled with ink is provided inside the inkjet recording head, and an orifice is disposed on one side wall of the ink pressurizing chamber facing the recording medium. The orifice turns the ink in the ink pressurizing chamber into particles and jets them toward the recording medium. A supply path for communicating with the ink tank and replenishing ink into the ink pressurizing chamber is formed on the other side wall of the ink pressurizing chamber. The upper wall of the ink pressurizing chamber is composed of a pressure plate made of a piezoelectric material known under the trade name "Bimorph". The pressure plate corresponds to the above-mentioned vibrator that rapidly displaces in response to an electric signal and changes the volume of the ink pressurizing chamber. When not recording, the ink is maintained in an equilibrium state by the static pressure of the ink in the ink tank and the surface tension of the ink at the orifice. When recording, an electric pulse is applied to operate the pressure plate, and the upper part of the ink pressurizing chamber is The walls are displaced inward. At this time, as the volume of the ink pressurizing chamber rapidly decreases, a portion of the ink within the ink pressurizing chamber becomes ink droplets and flies from the orifice toward the recording medium. After ejecting the ink droplets, the volume of the ink pressurizing chamber is restored to form the original equilibrium state. By repeating and continuing the above operations, ink droplets are sequentially ejected and desired recording is performed on the recording medium.

The inkjet recording device having the above configuration has a simple configuration and can eject ink droplets only during the period required for printing, making it easy to control the timing of ink droplet formation and to control the ink supply. Although this is an excellent recording method that is easy to perform and does not require a special ink supply device, it also has the following problems.
That is, the inkjet recording head has minute holes or orifices through which ink droplets are ejected, and during long-term suspension, the ink near the orifices dries and solidifies, depositing inside the orifice openings or causing the openings to become clogged. Because of the blockage, ink jetting becomes unstable and furthermore, jetting becomes impossible. In addition, viscosity increases due to moisture evaporation from locations where the ink is exposed to the atmosphere, which tends to reduce ink jetting performance.
Furthermore, dust floating in the atmosphere adheres to or enters the orifice opening, easily clogging the opening, and as the ink dries from the orifice opening, air bubbles may form inside the inkjet recording head, causing the ink to become particles. It has various drawbacks due to the aperture, such as making it impossible to put it into practical use.

The above-mentioned problems in the inkjet recording apparatus will be explained in more detail with reference to the drawings.

FIG. 1 is a block diagram showing the basic structure of an inkjet recording apparatus according to the present invention.

A recording head 1 that ejects ink particles onto a recording medium is in communication with a sub-ink tank 2, and a main ink tank 4 is connected to the sub-ink tank 2 via an ink replenishing device 3. Ink stored in the main ink tank 4 is sent to the recording head 1 via ink feed pipes 5'', 5', and 5.
The ink replenishing device 3 is driven by an ink level control circuit 6 to control the amount of ink supplied. The sub-ink tank 2 is provided with an opening 7 in its upper end wall to absorb fluctuations in fluid pressure caused by vibrations in the ink supply system, generation of bubbles, etc., and an ink detector 8 for detecting the amount of ink inside. There is. The detection signal from the ink detector 8 is input to the ink level control circuit 6. The main ink tank 4 is made of a flexible plastic film or the like with low gas permeability so that the ink does not come into direct contact with the atmosphere. The ink is disposed at a high position or has a configuration in which the ink is pressured and drawn out using a spring force or the like. The ink in the main ink tank 4 is supplied to the sub-ink tank 2 by an ink supply device 3 which is driven to open and close by an ink detector 8 and an ink level control circuit 6 so as to maintain the reference level. Therefore, in the sub-ink tank 2, the ink consumed during the recording operation is replenished, and the ink level is always maintained constant. The ink level in the sub-ink tank 2 and the surface tension of the ink in the orifice 9 provided in the recording head 1 form an equilibrium state of the ink during non-recording. The auxiliary ink tank 2 is mounted on a carriage (not shown) that moves relative to the recording medium (not shown) together with the recording head 1, moves on a running track in conjunction with the recording head 1, and opens a hole in the upper end. Fluctuations in ink liquid pressure that occur when the recording head 1 communicates with the outside air at 7 and travels;
In particular, it has a function of absorbing fluctuations in ink liquid pressure caused by vibrations of the ink supply pipe 5' and a function of removing air bubbles contained in the ink supply system. The ink supplied from the sub-ink tank 2 to the recording head 1 is pressurized by a piezoelectric material etc. that vibrates in response to a print signal, and is ejected as ink particles from an orifice 9, and is recorded as the recording head 1 travels. Recording is performed on the medium.

The above-mentioned inkjet recording device enables stable ink jetting with little fluid pressure fluctuation even when the carriage moves back and forth at high speed due to the action of the sub-ink tank 2 having the opening 7. On the other hand, the opening 7 at the upper end of the sub-ink tank 2 or the opening of the orifice, the ink increases in viscosity due to evaporation of the ink from the aperture 7 or the tip of the orifice, or the ink is easily clogged or trapped due to intrusion of dried and solidified dust.

The present invention was constructed by making full use of technical means to solve the above-mentioned problems, and by providing cap means in the orifice, ink tank hole, etc., ink can be released into the atmosphere when necessary during non-recording. The object of the present invention is to provide a new and useful inkjet recording device that is isolated from the inkjet recording device to prevent ink evaporation, dust intrusion, etc.

Hereinafter, one embodiment of the present invention will be explained in detail with reference to the drawings.

FIG. 2 is a block diagram of an inkjet recording apparatus showing one embodiment of the present invention. In the figure, the same reference numerals as in FIG. 1 indicate the same contents, and the explanation will be omitted.

The sub-ink tank 2 has a cap mechanism 10 disposed opposite to the opening 7, and an orifice cap 10 is provided at the opening of the orifice 9 of the recording head 1 to close the opening when the recording head 1 is placed at the stop position. 11 are provided.

During recording, the recording head 1 is moved away from the stop position and transferred to the printing position. Since the orifice cap 11 is fixed at the stop position, the orifice opens when the recording head 1 is moved to the printing position. Further, the cap mechanism 10 provided in the sub-ink tank 2 is opened at this time, and the opening 7 is communicated with the atmosphere. With the apertures 7 and orifices 9 open, recording is performed in the same manner as in the inkjet recording apparatus shown in FIG.

During non-recording, the cap mechanism 10 of the sub-ink tank 2 closes the opening 7 to seal the inside of the sub-ink tank 2 from the atmosphere. Further, the recording head 1 is transferred from the printing position to the stop position, and its opening is closed by the orifice cap 11. The cap mechanism 10 can be easily opened and closed by providing a drive circuit that responds to a recording preparation signal or the like.

As explained in detail above, the present invention completely seals the ink during the recording stop period by providing a cap in the opening, orifice, etc. in the ink supply system, thereby preventing clogging due to ink drying, dust floating in the air, etc. It is possible to effectively prevent the adhesion of water, the generation of bubbles, etc., and it is possible to obtain a highly practical inkjet recording device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic structure of an inkjet recording apparatus according to the present invention. FIG. 2 is a block diagram of an inkjet recording apparatus showing one embodiment of the present invention. 1... Recording head, 2... Sub-ink tank, 4
... Main ink tank, 7 ... Opening hole, 8 ... Ink detector, 9 ... Orifice, 10 ... Cap mechanism, 11 ... Orifice cap.

Claims (1)

[Scope of Claims] 1. A recording operation in an inkjet recording device in which ink supplied from an ink supply system is jetted as particles from an orifice of a recording head mounted on a carriage that moves relative to a recording medium. a first cap means that opens the orifice when the printer is in use and closes the orifice when the printer is stopped to seal the orifice from the atmosphere; The ink tank is provided in an ink tank that moves on a running track in conjunction with the recording head, communicates with the outside air through an opening at its upper end, and absorbs fluctuations in ink pressure that occur when the recording head runs. An inkjet recording apparatus characterized by comprising: second cap means which opens the opening and closes the opening when stopped to form a sealed state from the atmosphere.