JPS5811171A - Recorder - Google Patents

Abstract

PURPOSE:To equalize recording dots by dividing a common liquid chamber in an ink jet head in the direction of arrangement of orifices, mounting ink tanks at every each chamber and separately controlling ink pressure. CONSTITUTION:Heating resistors 2-1,...,2-n generate thermal pulses according to the input of signals, and ink is subjected to the action of the thermal energy and generates the change of a condition, such as cubical expansion, evaporation, etc. A pressure change due to the change of the condition is transmitted in the direction of the discharge orifices formed at the front edge section 7 of a substrate 1 and the end sections of the groovy patterns of a grooved plate 4, the pressure change is turned into operating force for discharging ink and ink is discharged and flown as liquid drops from the discharge orifices. Here, the common liquid chamber is divided into plural number in the vertical direction, the tanks 12-1,..., 12-m are mounted through pipes 8-1,...,8-m at every each liquid chamber 11-1,... 11-m, ink pressure is separately controlled, the pressure difference of ink in the upper section and lower section of the head is adjusted and the recording dots can be equalized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording apparatus that operates with an inkjet head standing approximately vertically and having a plurality of arranged orifices that eject ink from a liquid chamber by the action of thermal energy.

Among the non-impact recording methods that are attracting attention because of their extremely low noise during recording, inkjet recording is capable of high-speed recording and can be recorded on plain paper without the need for special fixing treatment. In that sense, it can be said to be an extremely powerful recording method.

There are various types of inkjet recording methods that use electrostatic attraction, pressure changes due to mechanical vibration, pressure changes due to thermal energy, etc. as methods for ejecting ink.

Recently, facsimile machines, printers, and the like using such inkjet recording heads have been developed and commercialized one after another, but in all of them, issues have arisen in increasing the speed and improving the image quality.

becomes important. Instead, a method has been considered in which the ink ejection orifices are arranged in a multi-array structure, lined up by the length of the recording width in the main scanning direction (horizontal direction), and printing is performed while feeding the recording paper in the sub-scanning direction (vertical direction). It will be done. but,
This method requires a large number of ink ejection orifices. For example, if the recording width is 210 trrm and the pitch of the ejection orimeter is 125 μm, the number is 1.
The number reaches 680 pieces. With this, Isogura became a very important island and became 17 years old.

Therefore, in order to perform high-speed recording at a lower cost, a head 1-1 having a configuration as shown in FIG.
5, run it in the main scanning direction (horizontal direction) 1-4, and roll the recording paper 1-2 in the sub-scanning direction 1-5.
A method is used in which data is sent out from No. 3 and recorded. In this case, the scanning speed in the sub-scanning direction is limited by the driving capacity of the mechanical system used for sub-scanning, and therefore there is a limit.

Furthermore, there is currently a limit to how shortening the ink ejection cycle can be achieved.

Therefore, it is conceivable to increase the number of ink ejection orifices in a multi-array to increase the amount of printing that can be performed at one time. However, if the number of ejection orifices increases too much, the difference in the size of the recorded dots at the top and bottom of the recording becomes noticeable, resulting in uneven image quality. This is a phenomenon that occurs because the head is placed vertically, so it is affected by gravity, and the back pressure at the top and bottom of the head is different. The relationship between back pressure and ink dot diameter varies depending on the nozzle shape, ink, recording paper, etc., but generally speaking, the larger the back pressure, the larger the dot diameter. Therefore, the recording dots are small at the top of the head and become larger toward the bottom of the head.

In view of these circumstances, the primary object of the present invention is to make the recording dots uniform in a recording apparatus in which an inkjet head with a multi-array structure stands up and scans.

In order to achieve the above object, the present invention divides a common liquid chamber into a plurality of parts in the direction of arrangement of orifices, provides an ink tank for each liquid chamber, and controls the ink pressure individually. This is to make it uniform.

Hereinafter, a detailed explanation will be given according to the illustrated embodiment.

FIG. 2 is an exploded view of only the print head section of the print apparatus of the present invention for convenience of explanation, and does not show details such as an ink supply system or a drive circuit for the head. Moreover, in the recording head of FIG. 2, heating resistors 2-1, 2-2, . . . are actually used as heating elements of the electrothermal converter.
. . . 2-n is placed on the insulating layer 9 on the substrate 1, and the common liquid chambers 11 to 1.11-2 for storing the recording liquid.・・・
・・・・・・・・・

11-m and long groove pattern 3-1.3-2. ....

The grooved plate 4 provided with 3-n f is joined and integrated so that the heating resistor and the elongated groove are located at corresponding positions.

And heating resistor 2-1.2-2 formed on substrate 1
．． ..., 2-n further includes a selection electrode (lead) 5-1.5-2 for selectively applying an electric signal to the resistor.
．． ..., 5-n and a common electrode (lead) 6 are connected.

Furthermore, as a means for applying a signal, a lead terminal 6' for a common electrode (lead) is provided in common to all the heating resistors on the opposite side of the substrate 1 from where the discharge orifice is formed. There is.

In this way, the common electrode (lead) terminal 6' and the selection electrode (lead) 5-1 serve as energizing means for applying a signal.
．． 5-2. . . , 5-n are formed to sandwich the insulating layer on the substrate 1.

Also, in FIG. 3, the X-
A Y cross-sectional view is shown.

To briefly describe the driving situation of the recording head shown in Fig. 2,
From an ink supply system (not shown), pipes 8-1, 8-2. −． 8-
Common liquid chamber 11-1.11-2. ..., 11
-m through long groove pattern 3-1°3-2. ...,
After the ink is introduced into 3-n, the terminal 5-1.5-
2,..., 5-n and 6', the heating resistor 2-
1.2-2. ..., 2-n selectively input signals. Then, according to the signal input, the heating resistor 2-1.2-
2. ....

2-n generates a heat pulse, and the ink undergoes state changes such as volumetric expansion and vaporization due to the action of the heat energy.

The pressure change due to the state change is transmitted in the direction of the ejection orifice formed by the front edge 7 of the substrate 1 and the end of the groove pattern of the groove plate 4, and this pressure change acts to eject the ink. This force causes the ink to be ejected and flew as droplets from the ejection orifice.

Here, the common liquid chamber is divided into multiple parts in the vertical direction,
Ink supply pipe 8-1 for each liquid chamber 11-1, 11-2, . . . , 11-m+. ．． 8-2°...
8-m to tanks 12-1, 12-2,...
.

By providing 12-m and controlling the ink pressure individually, it is possible to adjust the influence of gravity caused by vertically standing the head, that is, the difference in ink pressure between the top and bottom of the head, and make the recorded dots uniform. can.

In this embodiment, the division interval is set to 4. mrn. This value was determined based on the fact that good recording was actually obtained with L i 5 wn based on experiments.

In addition, there are ink supply tanks 12-1, 12-2, .
..., 12-m are provided, and the height of the ink liquid level in the tank is gradually lowered by an appropriate amount from the tank 12-1 to the lower tanks, so that each liquid chamber 11-1, 11-2°.・
・The ink pressure difference of 11-m was adjusted. This situation is shown in Figure 4. As a result of recording using this head with the configuration shown in FIG. 1, the difference in the size of the recording dots was almost negligible, and good recording was obtained.

Note that in this embodiment, the pressure was adjusted by controlling the height of the liquid level in the ink supply tank, but it is believed that similar effects can be obtained even if other pressure control means are used.

Further, although this embodiment has been described using a heating resistor as a thermal energy generating means, the same can be said of other devices using a laser irradiation means.

As described in the above descriptions 1 to 1, the present invention has a multi-array structure of ejection orifices vertically erected, which is scanned in the horizontal direction,
In a high-speed inkjet system that performs recording by vertically feeding recording paper, it has the effect of making recording dots uniform in size and improving image quality.

The present invention is also sufficiently effective against other difficulties caused by the difference in back pressure between the upper and lower parts of the head, such as wetting around the orifice periphery and receding of the ink meniscus.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the external appearance of the recording device of the present invention, and FIG.
4 to 4 are explanatory diagrams showing the main structure of the recording head according to the present invention. In the figure, 1-1...recording head, 1-2...recording paper, 1-3...
・Recording paper roll, 1-4...Main scanning direction, 1-
5 sub-scanning direction, 1...substrate, 2-1.2-2.
..., 2-n... heating resistor, 3-1.3-
2. ..., 3-n...groove pattern, 4...
... Grooved plate, 5-1.5-2. ..., 5-n...
...Selection electrode (lead), 6...Common electrode (lead), 6'...Terminal for common electrode, 7...
... leading edge, s-i. 8-2. ..., 8-m... Ink supply pipe, 9... Insulating layer, 10... Conductive layer, 1
1-1, 11-2°..., 11-m...
Common liquid chambers, 12-1, 12-2, . . . 12-m... Ink tank.

Claims (1)

[Claims] In a recording device that operates an inkjet head that is formed by arranging a plurality of orifices for discharging ink in a liquid chamber and standing approximately vertically, a common liquid chamber in the head is arranged in a plurality of orifices in the direction in which the orifices are arranged. A recording device characterized in that it is divided into two chambers, an ink tank is connected to each chamber, and the ink pressure is controlled individually in each chamber.