JPS63147651A - Liquid jet recording apparatus - Google Patents

Abstract

PURPOSE:To stably emit a recording liquid at the time of recording and to prevent the dripping of said liquid from a nozzle when no recording is performed, by providing a recording liquid tank at a position higher than the nozzle and providing a supply pipe equipped with an opening and closing valve at a position lower than the nozzle, and performing control such that said valve may be opened at the time of recording but closed at the time of non-recording. CONSTITUTION:An ink tank 2 provided at a position higher than the nozzle of a recording head 1, an ink supply pipe 3 equipped with an opening and closing valve 5 provided at a position lower than the nozzle and a control part 6, performing control so that the opening and closing valve 5 is opened at the time of recording but closed at the time of non-recording, are mounted. Therefore, at the recording time, the recording liquid in the recording head 1 is held to a state pressurized by the water head of the ink tank 2 present at a high position and the liquid can be stably emitted. At the time of non-recording, the opening and closing valve 5 provided to the ink supply pipe 3 is closed and, since said supply pipe 3 is present at a lower position, no water head is applied to the liquid and the dripping of the liquid from the nozzle can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid jet recording device, and more particularly, to a recording head equipped with a plurality of nozzles, a recording liquid is supplied from a recording liquid tank, and the ejected droplets are ejected. In a liquid jet recording apparatus that performs recording, the liquid supply means has been improved so that droplets can be ejected stably.

(Prior Art) In a conventional liquid jet recording device, a recording liquid tank containing recording liquid is placed at a position lower than the recording head, and the recording head and the recording liquid tank are connected with a pipe, so that the recording head is moved by capillary action. Ink, which is a recording liquid, was supplied.

However, with this arrangement of the recording liquid supply means, air bubbles mixed in the ink in the recording liquid tank and air dissolved in the ink tend to accumulate in the recording head installed above the ink, resulting in air leakage. This often blocks the nozzle passage and causes ink to fail to be ejected. Also like this,
If the supply of ink from the recording liquid tank to the recording head relies solely on capillary action, there is a risk that sufficient ink liquid will not be replenished when recording is performed at high speed.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid jet recording apparatus that eliminates the above-mentioned conventional problems and can perform stable liquid ejection even during high-speed recording.

[Means for solving problems]

In order to achieve such an object, the present invention provides a liquid jet recording device in which recording is performed by discharging recording liquid supplied from a recording liquid tank through a supply pipe from a nozzle of a recording head, at a position higher than the nozzle. A recording liquid tank provided therein, a supply pipe with an on-off valve □ interposed at a position lower than the nozzle, and means for controlling the on-off valve so as to control the on-off valve during recording and close the on-off valve when no recording is being made. It is characterized by the following:

[For production]

According to the liquid jet recording apparatus of the present invention, when recording is performed because the liquid level in the recording liquid tank is always at a higher position than the liquid ejection part of the recording head, the recording liquid in the recording head is pressurized by the water head. When recording is not performed, the valve installed in the supply path is closed, and since this valve is located at a low position, the liquid in the nozzle is kept in a stable state. No water head is applied, and liquid can be prevented from spilling out from the nozzle.

(Example) Examples of the present invention will be described below in detail and specifically based on the drawings.

FIG. 1 shows an embodiment of the invention. Here, 1 is a recording head, 2 is a recording liquid tank, and the recording liquid tank 2 is connected to the recording head 1.
By installing it at a higher position, a water head of height H from the center line A of the recording head 1 to the liquid level B in the tank 2 can be obtained, and that much liquid pressure can be applied through the ink supply pipe 3. so that it is guided to the recording head 1.

The recording liquid tank 2 is configured to conduct outside air through a communication port 4 provided at the upper part thereof, and an on-off valve 5 is provided in the supply pipe 3 at a position lower than the recording head 1 in the middle of the supply pipe 3. As will be described later, this on-off valve 5 is opened only during recording.

That is, if the on-off valve 5 is kept open until recording is not performed, the water head H described above will cause ink to easily seep out from the not-shown orifice provided in the recording pad 1, staining the surrounding area. There are many inconveniences such as unnecessary ink consumption.

Therefore, the valve is controlled so that it is opened only when recording.
6 is its control section. Regarding the above-mentioned water head H, it is necessary to take into consideration the driving speed when recording is performed by the recording head 1, the amount of ink ejected at that time, and the supply of ink to the tank 2. Through experiments, humans have determined that the water head H is 10ml11~150m.
It was confirmed that a range of m is suitable.

Next, an example of a multicolor recording apparatus to which the present invention is applied will be explained with reference to FIG.

In FIG. 2, 11 is a platen that can hold recording sheets and feed the sheets; 12 is a carriage on which the recording head 1 is mounted and can move freely in six directions in the axial direction of the platen 11;
3 is a guide shaft that slidably supports the carriage 12, and 14 has both ends fixed to the carriage 12, and is a pulley 15A.

This is a carriage drive belt that is stretched between the carriages 15B and 15B and is driven by the motor 16.

In this example, it is possible to print in four colors, namely yellow (Y), magenta (M), cyan (C) and black (B), and although not shown in the print head 1, these four colors can be printed. Recording units corresponding to colors are arranged, and color ink corresponding to each unit is supplied.

2Y, 2M, 2C, and 2B are recording liquid tanks 3Y containing the above-mentioned four color inks, yellow, magenta, cyan, and black, respectively.

3M, 3C and 3B have their ink supply tubes, and
5Y, 5M, 5C and 5B are individual supply pipes 3Y, 3M
, 3C, and 3B, in which the above-mentioned recording liquid tank group, ink supply pipe array, and on-off valve group are all arranged at the same height as in the example of FIG.

Reference numeral 17 denotes an ink supply tube row, that is, a tube bundle made up of a row of flexible supply tubes 3Y, 3M, 3C, and 3B. Carriage 12
It is held by the side holding part 12A and the middle holding member 17.

In the case of this embodiment, it is possible to print on paper size A2 horizontally, and the print head 1 has 128 nozzles and 63 nozzles.
．． The nozzles are arranged at intervals of 5 μm, and the ejection energy is supplied by an electrothermal conversion element, so that each nozzle is actually
Recording was performed by driving with a KHz drive signal, but
There was no problem in the supply of ink, and there was almost no air bubbles entering the recording head 1.

Figure 3 shows on-off valves 5Y and 5M for ink supply.

An example of the timing at which opening and closing of 5C and 5B are controlled by the control unit 6 (see FIG. 1) is shown.

Note that the control signals necessary for recording, such as print signals, are well-known signals generated through the control section of the recording apparatus itself, and detailed description thereof will be omitted.

Here, (A) is a print signal, and during its rise, a signal that drives the motor 16 in the main scanning direction as shown in (B) and a signal that drives the motor 16 in the opposite direction as shown in (C). is supplied, and during the rise of the main scanning drive signal, an image signal is supplied to the recording pad 1 as shown in (D), and ink is ejected.

Therefore, of course no recording is performed at the time of reversal, but since the time is short and there is no need to close the on-off valves 5Y to 5B each time, for example, as shown in (E) of this example, The valve is opened at the rising edge of the main scanning drive signal, and is closed at the same time as the printing signal falls. In this way, when recording is not performed continuously, the on-off valves 5Y to 5B are kept closed, so that each ink in the recording head 1 is kept close to atmospheric pressure, and the orifice is kept close to the atmospheric pressure. This prevents ink from leaching out.

In the above explanation, it is assumed that the ink is directly supplied to the recording liquid tank, but in order to stabilize the liquid level B (see Figure 1) in the recording liquid tank, each ink is stored in an ink cartridge. If ink is automatically supplied from these ink cartridges to the individual recording liquid tanks when the liquid level B falls, it is possible to provide even more stable ink supply.

In addition, if ink does not eject, it is necessary to suck ink from the recording head l and discharge the highly viscous ink liquid and air bubbles that have accumulated inside. All you have to do is open the valve.

〔Effect of the invention〕

As explained above, according to the present invention, since the liquid level in the recording liquid tank is maintained at a higher position than the nozzle of the recording head, the pressure corresponding to the head of the recording liquid in the nozzle during recording is applied to the recording liquid in the nozzle. is added appropriately, and stable ejection of recording liquid is possible at all times.Furthermore, the lowest position of the supply pipe from the recording liquid tank is lower than the recording head nozzle,
An on-off valve is provided there, and this on-off valve is closed when no recording is being performed, so that no pressure is applied to the recording liquid in the nozzle due to the water head when no recording is being performed. By keeping the recording liquid near the lowest position, it can further contribute to preventing the recording liquid from seeping out from the orifice.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the basic configuration of a liquid jet recording device according to the present invention, FIG. 2 is a perspective view showing an example of the configuration of a multicolor recording device to which the present invention is applied, and FIG. It is a timing chart of the opening and closing operation of such an on-off valve. 1... Recording head, 2.2Y, 2M, 2C, 2B... Recording liquid tank, 3.3Y
, 3M, 3C, 3B...Ink combined supply tube, 5.5Y, 5
M, 5C, 5B--Opening/closing valve, 6--Control unit, 12--Carriage, 16--Motor, 17--Holding member. Ward ~ Taste

Claims (1)

[Scope of Claims] In a liquid jet recording device in which recording is performed by discharging recording liquid supplied from a recording liquid tank through a supply pipe from a nozzle of a recording head, the recording liquid is provided at a position higher than the nozzle. a tank, the supply pipe having an on-off valve interposed at a position lower than the nozzle;
A liquid jet recording device characterized by comprising: means for controlling the on-off valve to open the on-off valve during recording, and close the on-off valve when no recording is to be performed.