JPH0457501B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a liquid jet recording device that performs recording using flying droplets formed by discharging liquid from a discharge port, and particularly to a liquid jet recording device that uses thermal energy. There are various types of liquid jet recording devices, but
Among them, for example, the German Open Gazette (OLS)
The liquid jet recording device disclosed in Publication No. 2944005 is
High-speed color recording is easy, and the recording head, which is the main part of the output section, has ejection ports (orifices) arranged in high density for ejecting recording liquid and forming flying droplets. In order to be able to
At the same time, it is possible to obtain high resolution, and at the same time, it is possible to make the recording head more compact and suitable for mass production.Furthermore, in the semiconductor field, technological advances and reliability improvements are remarkable, such as IC technology and microprocessing technology. Recently, it has been attracting a lot of attention because it is easy to make it long and planar (two-dimensional) by making full use of its advantages. However, in the case of a conventional recording head of the multi-orifice type, a liquid flow path corresponding to each orifice is provided, and thermal energy is applied to the liquid filling the liquid flow path for each liquid flow path to create a corresponding orifice. An electrothermal converter is provided as a means for ejecting liquid to form flying liquid, and each liquid flow path is supplied with liquid from a common liquid chamber communicating with each liquid flow path. It is becoming. The common liquid chamber is
Because it is necessary to place recording paper above it, and because it is necessary to place an electrothermal converter below it,
It cannot be installed as a large enough space. In such a case, if a structure in which several hundred or more orifices are arranged densely, the amount of liquid used increases dramatically compared to the size of the common liquid chamber, and furthermore, each of the above-mentioned problems occurs. Due to reasons such as the liquid flow path becoming narrower and the liquid flow path wall resistance increasing, the liquid supply (refill) cannot follow the flow during high-speed recording, and droplet formation becomes unstable. A problem has arisen in that it is no longer possible to record high-quality images at high speed. One way to solve this liquid supply problem when performing high-speed recording is to install a second liquid that stores liquid for replenishing the common liquid chamber below the electrothermal converter at the bottom of the common liquid chamber. It has been considered to arrange chambers and provide a supply port connecting these liquid chambers in the installation gap of the electrothermal converter. However, depending on the installation style of this supply port, the liquid supply to the orifice may still not be able to keep up, or there may be a large difference in the frequency limit between orifices due to differences in the location of the orifice. This is the actual situation. The present invention has been made in view of the above points, and a main object of the present invention is to provide a liquid jet recording device that can faithfully perform high-density and high-speed recording. Another object of the present invention is to provide a liquid jet recording device that has little variation in droplet flight between ejection ports and is suitable for high-quality image recording. The liquid jet recording device of the present invention has a plurality of ejection ports provided for electrothermal converting liquid to form flying droplets by using thermal energy, and a plurality of ejection ports that communicate with these ejection ports to form flying droplets. a first liquid chamber to which a liquid for forming target droplets is supplied; and a lower part of the first liquid chamber which stores a liquid for replenishing the liquid to the first liquid chamber through a supply port. A second liquid chamber provided, and a plurality of electrothermal converters serving as means for generating the thermal energy provided corresponding to each of the discharge ports, each of the electrothermal converters comprising: A heat acting surface as a surface on which generated thermal energy acts on the liquid is provided on the bottom surface of the first liquid chamber, and each of the discharge ports is provided opposite to the bottom surface and is adjacent to each other. In the liquid jet recording device, a separation wall is provided in the first liquid chamber to isolate heat acting surfaces and ejection ports, and each ejection port has a liquid flow path for the liquid, wherein the supply port includes: At least one supply port is provided for every 100 discharge ports, and the cross-sectional area Sh of the supply port is Sh≧(Lh・Nn/Ln・Nh) ^1/2・Sn……(2) (However, Sn is the cross-sectional area of one liquid flow path, Nn is the total number of discharge ports, Ln is the length of the liquid flow path, Nh is the total number of supply ports, and Lh is the length of the supply port). It is characterized by its size that satisfies The liquid jet recording apparatus of the present invention having the above-described configuration exhibits excellent performance with excellent response fidelity and reliability to high-frequency recording signals and little variation in droplet flight between orifices. Hereinafter, the present invention will be explained in more detail with reference to the drawings. 1 to 3 are diagrams showing an outline of a liquid jet recording device according to the present invention, with FIG. 1 being a schematic exploded view for explaining the internal structure, and FIG. 2 being a schematic plan view thereof. 3 are cross-sectional views taken along the dashed line AB in FIG. 2. The liquid jet recording apparatus 100 shown in FIGS. 1 to 3 includes a substrate 101, an electric converter 102 provided on the substrate 101, a front wall plate 103 for forming a first liquid chamber 110, and a rear wall plate 103 for forming a first liquid chamber 110. A wall plate 105, a side wall plate 104 held at both ends by these wall plates 103 and 105, and a through hole 109 forming an orifice 108 provided corresponding to each electric converter.
The first liquid chamber 11 isolates the orifice plate 107 provided with the orifice plate 107 and the adjacent orifice 108 and forms a liquid flow path 121 for each of the orifices.
A second liquid chamber provided at the bottom of the substrate 101 stores a liquid for replenishing the liquid to the first liquid chamber through an isolation wall 117 provided in the substrate 101 and a supply port 118 drilled in the substrate 101. chamber 119 and second liquid chamber 11
9 and a supply pipe 120 for supplying liquid. The electric converter 102 includes a heating resistance layer 111, a selection electrode 112, a common electrode 114, which are provided in parallel on the heating resistance layer 111 except for a part of the heating resistance layer 111, in order from the substrate side on the substrate 101. Liquid chamber 1
At least a protective layer 113 is provided on a portion of the liquid in the liquid that is in direct contact with the liquid. When the heat generating resistive layer 111 is energized through the selection electrode 112 and the common electrode 114, it mainly generates thermal energy in the heat generating portion 116 between these electrodes. The heat acting surface 115 is a place where the generated heat acts on the liquid, and has a close relationship with the heat generating part 116. A valve is generated in the liquid due to the heat action on the heat action surface 115, and the pressure energy causes the liquid to be ejected from the orifice 108 as a flying droplet, thereby performing recording. In order to drive each of the electrothermal transducers 102 according to a recording signal to eject a droplet from a predetermined orifice 108, a signal voltage is supplied through a selected selection electrode 112 and a common electrode 114. Implemented. In the configuration of the liquid jet recording device described above,
In the present invention, at least one supply port 118 is provided for every 100 orifices, and the cross-sectional area Sh of the supply port 118 is provided with a specified size. That is, the first liquid chamber 1 drilled in the substrate 101
If the number of supply ports 118 connecting the second liquid chamber 10 and the second liquid chamber 119 is less than one per 100 discharge ports, even if the supply ports 118 are sufficiently large, the position of the orifice may vary. Depending on the location of the orifice, there will be a large difference in the frequency limit between the orifices. In order to further reduce the dispersion in discharge between orifices, for each 32 orifices,
It is more preferable that one or more of them be provided. Further, the cross-sectional area Sh of the supply port 118 needs to be a size that satisfies equation (1). Note that the length Ln of the liquid flow path 121 here refers to the length Ln of the liquid flow path 121.
It does not refer to the entire length of the liquid flow path formed by 7, but refers to the distance from the boundary between the common liquid chamber of the first liquid chamber and the liquid flow path to the center of the orifice 108, as shown in FIG. . If the cross-sectional area Sh of the supply port 118 is smaller than the value determined by the above formula (1), no matter how many supply ports are provided, when high-frequency recording is attempted, the liquid discharge from the orifice will be affected. However, this is not appropriate because the liquid supply may not be able to follow it. FIG. 4 is a schematic diagram showing a preferred modification of the installation style of the first liquid chamber 110 and the supply pipe 120 in the liquid jet recording device of the present invention. The number of installed ports 118 and the cross-sectional area Sh must satisfy the above-mentioned requirements. Hereinafter, the present invention will be explained in more detail according to Examples. Example 1 Si whose surface was thermally oxidized to form _two SiO layers with a thickness of 3 μm
A Ta layer with a thickness of 2000 Å is placed on the substrate as a heating resistance layer.
After laminating an Al layer with a thickness of 1 μm as an electrode, 128 heat generating part (heater) arrays each having a shape of 30 μm x 150 μm were formed at a pitch of 8 heaters by a photolithography process. In addition, it is used as a film to prevent Ta layer from oxidation, to prevent penetration of ink liquid, and to resist mechanical shock caused by valves generated when liquid receives thermal energy.
A protective layer was formed by sequentially stacking _two SiO layers with a thickness of 0.5 μm and a SiC layer with a thickness of 1 μm by sputtering. On this substrate, the cross-sectional area is 7.1 × 10 ^-2 mm ² (pore diameter is 300 μm) and the length
Three 0.5mm ink supply holes were provided. The holes were arranged at 4 mm intervals from the side surface of the first liquid chamber at positions 1 mm away from the portion where the liquid flow path was provided. Next, a separation wall, a front wall plate, a rear wall plate, two side wall plates, an orifice plate, a second liquid chamber, and a supply pipe are installed on this substrate as shown in Figures 1 to 3, and a liquid jet recording device is installed. was created. The cross-sectional area of the liquid flow path partitioned by the separating wall is 1.6 × 10 ^-3 mm ² and the length is 1 mm.
A total of 128 orifices were installed.
Note that the value of (Lh·Nn/Ln·Nh) ^1/2 ·Sn in this example is 7.4·10 ³ mm ² . When the liquid jet recording device created in this way was operated under the following conditions, there were two cases: when a droplet was ejected from only one orifice, and when a droplet was ejected from all 128 orifices simultaneously. , their discharge frequency limit was the same, 8KHz. Further, no difference was observed in the ejection characteristics of droplets from the orifices near both ends of the head and the orifice in the center, and there was no difference in the ejection condition due to the difference in the orifice position. [Liquid jet recording device driving conditions] Applied voltage: 27 volts Pulse width: 10 μsec Frequency: 0.5 to 10 KHz Variable Examples 2 to 4 and Comparative Examples 1 to 3 In the liquid jet recording device of Example 1, the supply port was disconnected. A completely similar liquid jet recording device was manufactured except that the area was changed, and an ejection characteristic test was conducted under the same conditions as in Example 1, and the results shown in Table 1 were obtained. Examples 5 to 16 In the liquid jet recording device of Example 1 or the liquid jet recording device having the cross-sectional structure shown in FIG. 4, the size of each part determining the structure was changed as shown in Table 2. . However, Hn represents the height of the liquid flow path, and Hc represents the height of the first liquid chamber. When the ejection characteristics of these liquid jet recording apparatuses were tested in the same manner as in Example 1, good results were obtained in all cases, exactly the same as in Example 1.

[Table] *1: When only one orifice is driven
*2: When all orifices are driven during operation

【table】

[Table] *2 When only one orifice is driven *3 When all orifices are driven simultaneously

[Brief explanation of the drawing]

1 to 3 are diagrams showing an outline of a liquid jet recording device according to the present invention, in which FIG. 1 is a schematic exploded view, FIG. 2 is a schematic plan view thereof, and FIG. FIG. 2 is a sectional view taken along the dashed line AB in FIG. 2; FIG. 4 is a schematic sectional view showing a preferred modification of the liquid jet recording apparatus of the present invention. 100: Liquid jet recording device, 101: Substrate, 1
02: Electric converter, 103: Front wall plate, 104: Side wall plate, 105: Rear wall plate, 106: Supply pipe, 10
7: Orifice plate, 108: Orifice, 10
9: Through hole, 110: First liquid chamber, 111: Heat generating resistance layer, 112: Selection electrode, 113: Protective layer, 11
4: Common electrode, 115: Heat action surface, 116: Heat generating part, 117: Separation wall, 118: Supply port, 11
9: second liquid chamber, 120: supply pipe, 121: liquid flow path.

Claims (1)

[Scope of Claims] 1. A plurality of ejection ports provided for ejecting liquid to form flying droplets by using thermal energy, and a plurality of ejection ports communicating with these ejection ports to form the flying droplets. a first liquid chamber to which a liquid is supplied for forming the
a second liquid chamber provided at a lower part of the first liquid chamber for storing a liquid for replenishing the liquid to the first liquid chamber through a supply port; and a second liquid chamber provided corresponding to each of the discharge ports. , a plurality of electrothermal converters serving as means for generating the thermal energy, each of the electrothermal converters having a heat acting surface as a surface on which the generated thermal energy acts on the liquid; Each of the discharge ports is provided on the bottom surface of the first liquid chamber, and each of the discharge ports is provided opposite to the bottom surface, and a separation wall is provided in the first liquid chamber to isolate the adjacent heat acting surfaces and the discharge ports. In a liquid jet recording device having a liquid flow path for the liquid for each ejection port, the supply port is provided at a ratio of at least one per 100 ejection ports, and The cross-sectional area Sh is Sh≧(Lh・Nn/Ln・Nh) ^1/2・Sn……(1) (However, Sn is the cross-sectional area of one liquid flow path, Nn is the number of total discharge ports, Ln is the length of the liquid flow path, Nh is the total number of supply ports, and Lh is the length of the supply ports.