JPH062413B2 - Liquid jet recording head - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid jet recording head, and more particularly to a liquid jet recording head having means for generating a small droplet of recording liquid used in a so-called liquid jet recording system.

A recording head of a liquid jet recording apparatus applied to a liquid jet recording system generally includes a fine droplet discharge port (orifice), a liquid flow path, and an energy acting portion provided in a part of the liquid flow passage, and the acting portion. An energy generator for ejecting the liquid that generates the droplet forming energy that acts on the liquid.

Energy generators are, for example, USP 3683212 and USP 39463.
In the recording method disclosed in 98, etc., there is a description using an electromechanical transducer such as a piezo element. One of the recording methods disclosed in Japanese Patent Laid-Open No. 54-59936 is an energy recording method. An example in which an electrothermal converter is used in the action part is described. Further, in another recording method disclosed in Japanese Patent Laid-Open No. 54-59936,
No special means is provided in the energy acting portion, and the acting portion is irradiated with an electromagnetic wave such as a laser to be absorbed in the liquid there to generate heat, and droplets are ejected and ejected by the effect of the heat generation for recording. In other words, there is a description that the liquid irradiated with electromagnetic waves is an energy generator.

As described above, in the liquid jet recording method described above, mechanical pressure or thermal energy (or electromagnetic energy) is applied to the liquid in the energy acting portion to obtain a driving force for ejecting the liquid. In this recording method, in order to improve the quality of a recorded image and enable high-speed recording, the recording head to be applied stably and repeatedly ejects droplets for a long time, Further, it is necessary to improve the droplet forming frequency of the recording head (the number of droplets formed per unit time = the droplet forming frequency per unit time) and stabilize the droplet forming characteristics.

In the past, however, it was difficult to say that all of these could be solved sufficiently.

The present invention has been made in view of the above technical problem, and aims to improve the total number of droplets ejected per ejection port, that is, the durable ejection number (durability pulse number), and An object of the present invention is to provide a liquid jet recording head in which droplet formation characteristics that are continuous throughout are stabilized.

Further, such a liquid jet recording head of the present invention is provided with an ejection port for ejecting a liquid, a liquid path communicating with the ejection port, and corresponding to the liquid path, for ejecting the liquid from the ejection port. A straight line A that passes through the center of the discharge port and is perpendicular to the discharge port surface on which the discharge port is disposed, and the electrothermal converter that is parallel to the straight line A. A plane H2 perpendicular to a plane H1 including the straight line B passing through the center of the converter and including the straight line A; a plane H3 perpendicular to the plane H1 and including the straight line B; and a wall of the liquid passage. Let S _{N be} the maximum area of the cutting plane parallel to the plane H 4 perpendicular to the planes H 1, H 2, and H 3 in the enclosed space region, and let S _H be the area of the electrothermal converter, S _N / S _H Has a value of 2
It is 50 or less and the distance a between the straight line A and the straight line B is a
Is larger than the distance b from the surface of the discharge port to the surface on which the electrothermal converter is arranged immediately below the center of the discharge port, and a / b is 50 or less.

According to the present invention, it is possible to provide a liquid jet recording head which has good droplet ejection stability during continuous recording for a long time and has an improved durable pulse number for droplet ejection. In order to achieve the object of the present invention more effectively, the value of S _N / S _H should be 50.
The following is preferable.

FIGS. 1 (a) and 1 (b) are views for explaining S _N and S _H in the present invention. FIG. 1 (a) is a schematic plan view and FIG. 1 (b) is It is a typical perspective view. In both figures, 102 is an energy generator, 104 is a liquid flow path, 106 is a discharge port, and 107 is an energy acting part. In Fig. 1 (b), the straight line A
Is a straight line that passes through the center of the ejection port 106 and is perpendicular to the ejection port surface (atmospheric side surface of the ejection port 106). Straight line B
Is a straight line parallel to the straight line A and passing through the center of the energy generator 102. In the present invention, as shown in the figure, the distance a between the straight line A and the straight line B is
A head that is larger than the distance b from the ejection port surface to directly below the center of the ejection port is considered. The plane including these two straight lines (straight line A and straight line B) is the plane H1. Plane H
2 is a plane perpendicular to the plane H1 and including the straight line A, and plane 3 is a plane perpendicular to the plane H1 and including the straight line B.

The plane H4 is a plane perpendicular to the planes H1, H2, and H3 in the space area surrounded by the planes H2 and H3, and the liquid flow channel wall forming the liquid flow channel 104.

S _{N in the} present invention means the maximum area of the plane H4. The center of the energy generator is the midpoint in the length direction of the energy generator with respect to the straight line direction perpendicular to the straight line A and parallel to the plane H1, and the center of the energy generator with respect to the straight line direction perpendicular to the plane H1. Is the midpoint of the length direction.

The area S _H of the energy generator in the present invention refers to the area between the electrodes connected to the member that generates energy, for example, the heating resistor that is an electrothermal converter, that is, the area of the gap between the electrodes. . Further, even when there is a protective layer or the like on the energy generator, the area _SH of the energy generator refers to the area of the gap between the electrodes connected to the member that generates energy. When the energy is electromagnetic energy and the energy is directly applied to the liquid, it is the maximum area of the liquid in the liquid flow path that absorbs the energy when the liquid is cut along a plane parallel to the plane H4.

The invention will be further described by means of a preferred embodiment example.

FIG. 2 is a schematic perspective partial view (partially cutaway view) for explaining an embodiment of the present invention. In the figure, 101 is a substrate, 103 is a flow path wall, and 105 is a discharge port plate having a discharge port 106. 102, 104, 107 in the figure are
These numbers are the same as those in FIGS. 1 (a) and 1 (b), respectively. In addition, in this embodiment, the energy generator 102 is referred to as an electrothermal converter 102.

In the example of the embodiment of the present invention, the electrothermal converter 102 in the liquid flow path 104 applies thermal energy to the liquid, thereby ejecting droplets from the ejection port 106. It has a bent structure on the way from the energy acting portion 107 of the liquid flow path 104 to the discharge port 106.

In the example of the embodiment of the present invention, the so-called L-shaped discharge (side sho
oter) shape.

A simple manufacturing procedure of this embodiment example will be described.

In this embodiment, first, an electrothermal converter 102 having the structure described in OLS 2843064 is provided on the substrate 101 as an energy generator, and then a photosensitive resin film (for forming the flow path wall 103 is formed ( The substrate 101 and the electrothermal converter 102 were laminated using a dry film photoresist; film thickness 25 to 100 μm), and the photosensitive resin film was exposed and developed to form a liquid flow path 104. Next, another photosensitive resin film serving as the ejection port plate 105 is further laminated, exposed and developed, and the ejection port 10
6 was formed to fabricate the sample head of the present embodiment (note that the electrothermal converter 102 was provided with electrodes and wirings leading to the electrodes were also provided).

In the embodiment example manufactured as described above, first, the value of S _N is set to 1250.
Fixed to 00μm ^2, to produce a one of changing the value of S _H, (the lower limit voltage V1, and the upper limit voltage V2) stable liquid voltage drop is discharged from the discharge port and one outlet The total number of droplets ejected from (expressed as the number of endurance pulses) was measured.

The results are shown in Table 1.

As shown in Table 1, in the embodiment examples of No. 1 to No. 4 in which S _N / S _H is 250 or less, the voltage margin width (V2-V1) is large, and The number of endurance pulses also became a sufficiently large value.

Next, the value of S _H was fixed at 1000 μm ² and the value of S _N was changed to prepare, and V1, V2 and the number of endurance pulses were measured in the same manner.

The results are shown in Table 2.

As shown in Table 2, with respect to the embodiment example in which S _N / S _H is 250 or less (S _N = 250,000 or less), the voltage margin width is large and the number of durable pulses is also a sufficient value.
However, in Production No. 9 (S _N = 500,000) in which S _N / S _H exceeded 250, the voltage margin width was relatively good, but the number of durable pulses was small, and it was a value that was difficult to use in practice.

S _N / S _H Although the fabrication No.9 exceeding 250 is reduced compared both numbers voltage margin width and durability pulse to manufacture No.5 to manufacture No.8, this is the S _H It is considered that the energy loss for ejecting droplets increases as the value of S _N increases with respect to the value. That is, that is, when the value of S _N becomes larger than the value of S _H, the amount of energy required to eject the liquid with respect to the energy that the energy generating body acts on the liquid increases. Therefore, S _N / S _H is 25
In Production No. 9 which exceeded 0, the voltage V1 at which stable ejection of droplets started was also a high value as compared with the others.

In the above description, one energy generator corresponds to one discharge port, but S _N / S _H
The same can be said for the relationship of 1 even when there are a plurality of energy generators for one discharge port.

For example, when there are two or more energy generators, the S _N / S _H relationship may be set mainly for the energy generator that discharges liquid droplets. In addition, if it is difficult to determine which energy generator is the main and the other is the same as those involved in droplet ejection, set the S _N / S _H relationship for the energy generator closest to the ejection port. Just do it.

Further, the relationship between S _N and S _H is not limited to the so-called L-shaped discharge in which the liquid is bent from the liquid flow path 104 and is discharged as droplets from the discharge port 106 as in the present embodiment example. It can also be applied to a device in which a discharge port is provided at the end. However, S _H at this time is the same as the above description, but S _N is a plane including a straight line passing through the center of the energy generator and parallel to the discharge port surface, the discharge port surface, and the channel wall. In the enclosed space area, it is the maximum area of the plane that intersects perpendicularly with the ejection port surface. In addition, the center of the energy generator in this case also indicates the same portion as described above.

Further, as described above, the energy generator may be one using electromagnetic energy. Furthermore,
Although the shape of the energy generator is shown in FIGS. 1 and 2, it is not limited to such a rectangle and may be deformed as long as droplets can be ejected. Also in this case, the center of the energy generator is determined as described above.

Even if there is a protective layer or the like on the energy generator and the electrodes of the energy generator are not in direct contact with the liquid, the area and center line may be determined between the gaps of the electrodes of the energy generator. Clogging, in which case it may be considered that there is no protective layer.

Further, in the case of the L-type ejection liquid jet recording apparatus as in the present embodiment example, as shown in the schematic sectional partial view of FIG.
Between the length a from the center of the energy generator 102 to the center line AA ′ of the discharge port 106 and the length b from the atmospheric side surface of the discharge port 106 to the bottom surface of the liquid flow path 104 directly below the center of the discharge port are: It is desirable to have a relationship like this.

That is, it is desirable to set the positional relationship between the ejection port and the energy generator so that the value of a / b is preferably 50 or less, more preferably 10 or less. More specifically, in the liquid jet recording apparatus having the same structure as that of this embodiment, the liquid ejection recording apparatus having a / b of 50 has a voltage margin width of 17 V and an endurance pulse number of about 5 × 10 ⁷ . However, the values of a / b of 10 were 10 V or more and about 6 × 10 ⁷ cells, respectively.

In this way, the durability can be further improved by setting the value of the ratio of SN to SH to be in the above range and by setting the value of a to b to such a value.

Table 3 below shows a / under typical SN / SH values.
The number of endurance pulses with respect to the value of b is shown.

Usually, the damage to the electrothermal converter when the bubbles generated by the electrothermal converter are defoamed is greatly affected by the discharge port side than the electrothermal converter.

The smaller the value of a / b, the smaller the movement of the ink on the ejection port side during defoaming, so the above-mentioned damage becomes smaller. However, as can be seen from Table 3, SN / SH is 250 or less, and a When / b is 50 or less, the damage at the time of defoaming can be reduced and the durability is further improved.

Also in this case, the center of the energy generator must be determined in order to determine a, but the same determination method as that of the center line of the energy generator in the case of determining S _N can be used. Therefore, the energy generator is similarly determined even if it is based on the irradiation of electromagnetic energy.

As described above, according to the present invention, the reliability of droplet discharge is improved by increasing the voltage margin width, and the major advantages such as simplification and miniaturization of the drive circuit design of the energy generator of the energy acting portion or the energy applying means. There is.

Furthermore, it is possible to obtain a liquid jet recording head that can perform stable droplet discharge for a long time.

Further, when the head of the recording apparatus is configured as in the embodiment shown in FIG. 2, a high density of about 20 lines / mm is obtained when multiple ejection ports are formed in the same head to form a multi-head. In addition, it is possible to obtain higher quality image recording by improving the reliability of droplet discharge.

[Brief description of drawings]

1 (a) and 1 (b) are views for explaining the present invention,
1 (a) is a schematic plan partial view, FIG. 1 (b) is a schematic perspective view, FIG. 2 is a schematic perspective partial view (partially cutaway view) showing an example of the present embodiment, and FIG. The drawing is a schematic partial sectional view for explaining an embodiment of the present invention. 101 ... Substrate 102 ... Energy Generator 103 ... Flow Path Wall 104 ... Liquid Flow Path 105 ... Discharge Port Plate 106 ... Discharge Port 107 ... Energy Applying Section

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Katsuyuki Yokoi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Masami Ikeda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation (56) References JP-A-55-128465 (JP, A) JP-B-59-31945 (JP, B2)

Claims (2)

[Claims] 1. A discharge port for discharging a liquid, a liquid channel communicating with the discharge port, and a thermal energy provided to correspond to the liquid channel and used to discharge the liquid from the discharge port. A straight line A that passes through the center of the discharge port and is perpendicular to the discharge port surface on which the discharge port is arranged, and a straight line B that is parallel to the straight line A and that passes through the center of the energy generator. A plane H2 that is perpendicular to a plane H1 that includes and includes the straight line A, a plane H3 that is perpendicular to the plane H1 and includes the straight line B, and a wall of the liquid passage, when the plane H1, H2, the maximum area of a sectional plane parallel to the plane perpendicular H4 to H3 _{S N,} the area of the electrothermal transducer and _{S H,} the value of S N / _{S H} 25
It is 0 or less, and the distance a between the straight line A and the straight line B is a.
Is larger than the distance b from the surface of the ejection port to the surface on which the electrothermal converter is arranged immediately below the center of the ejection port, and a / b is 50 or less. 2. The liquid jet recording head according to claim 1, wherein the value of S _N / S _H is 50 or less.