JPS609907B2 - Multi-orifice liquid injection recording head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording head applied to a liquid jet recording apparatus that performs recording by jetting liquid and forming flying droplets.

The impact recording method has recently been gaining acclaim in that the noise generated during recording is extremely small to the extent that it can be ignored. Among them, the so-called inkjet recording method (liquid jet recording method) is capable of high-speed recording and can record without the need for special processing such as fixing on plain paper.
is an extremely powerful recording method, and various methods have been devised so far, some have been improved and commercialized, and others are still being worked on to put them into practical use. be. In this liquid jet recording method, recording is performed by flying droplets of a recording liquid called ink and making them adhere to a recording member. There are several types of methods depending on the generation method and the control method for controlling the flying direction of the generated droplets.

Among them, for example, USP3683212, USP374
The liquid dome recording method described in publications such as No. 7120 and USP 39463 is a method in which liquid is ejected from an ejection orifice in response to a recording signal, and the liquid bottle is attached to the surface of a recording member to perform recording. This is a drop-on ship mand recording method, and only the droplets necessary for recording are ejected, so there is no need to provide special means for collecting or processing ejected liquid that is not necessary for recording, simplifying the device itself. Recently, it has attracted particular attention because it can be made smaller, there is no need to control the direction of flight of droplets discharged from a discharge orifice, and multicolor recording can be easily performed.

Furthermore, the present applicant has developed a liquid jet recording method which has a completely different principle of droplet formation from the liquid jet recording method described above.
It was disclosed in Japanese Patent No. -59936.

This liquid jet recording method is based on the above-mentioned DMP-ondeman.
Not only can it be applied extremely effectively to the D recording method, but it can also easily be used to create a high-density multi-orifice recording head with an F-mounted 11I type, which allows high-resolution, high-quality images to be obtained at high speed. have. These liquid jet recording methods are suitable for so-called multi-orifice recording, in which a large number of orifices are arranged in an array and recording is performed over a predetermined area or a predetermined area at one time, and high-speed recording is possible.

In particular, the liquid jet recording method disclosed in Japanese Unexamined Patent Publication No. 54-59936 is capable of arranging orifices at a high density of, for example, one needle per rib or more. In addition to being able to record at high resolution, the density is the same as the resolution of the image obtained, but it is full-line.
Since the orifices are arranged in a row, the recording speed can be greatly improved. However, as described above, when orifice or single-orifice recording heads are arranged at a high density, there are several problems that may impede recording stability and ensuring recording quality.

In other words, it is a matter of stably and uniformly supplying liquid (ink) to each energy acting part suitable for the orifice, droplet ejection efficiency, and droplet formation frequency (equivalent to the number of droplets ejected per unit time). .

The former is mainly a factor that hinders the high-density arrangement of orifices, and in order to solve this problem, it is especially important to accurately estimate the minimum limit of the common liquid chamber volume, which will be described later. The droplet ejection efficiency is determined by the fact that the energy generated according to the recording signal input to the energy application section is effectively applied to the three liquids in the action section, and based on this, the droplet is ejected from the ejection orifice according to the recording signal input to the energy application section. It cannot be improved unless the liquid is discharged faithfully and with good response, but this is due to the arrangement of the multiple liquid flow paths, the arrangement of the liquid in front of the energy acting part, and the orifice at the tip. an orifice side end having an energy application section; an inlet side end disposed behind the energy application section and having an inlet for supplying liquid to the energy application section; It is thought that this greatly depends on the shape of the common liquid chamber, the positional relationship between the four, the volume relationship, and the amount of energy applied to the liquid in the energy application section for ejecting droplets. Furthermore, the factors involved in the droplet ejection efficiency mentioned above are:
It is also an important factor in determining the droplet formation frequency.

The above is particularly true in the apparatus embodying the liquid jet recording method disclosed in Japanese Unexamined Patent Publication No. 54-59936. When arrayed, the effect is extremely large.

In other words, in the liquid jet recording method disclosed in Japanese Unexamined Patent Publication No. 54-59936, droplets are ejected based on changes in the thermal state of the liquid. In connection with improvement, it has a particularly large effect on improving droplet ejection energy efficiency.

However, these two problems cannot be easily solved based on theoretical predictions. In other words, for example, the mechanical properties of the liquid such as the Young's modulus and compressibility of the structural material of the recording head, and the thermal properties of the liquid such as the specific heat and thermal conductivity in the recording method of Tokusekki No. 54-59936. The reason for this is that it is difficult to select and control a small number of factors related to the droplet ejection closing mechanism due to the fact that the factors do not necessarily differ greatly in terms of order. Therefore, the inventors of the present invention fabricated a large number of prototype multi-orifice recording heads with various structures, and based on newly discovered facts from information on recording characteristics obtained through experiments with these, the inventors developed a multi-orifice liquid. We succeeded in numerically elucidating the design method of the jet recording head.

Furthermore, the effectiveness of the design method was confirmed by examining the characteristics of a multi-orifice recording head manufactured based on this design method. The present invention is based on the above points, and is based on the above-mentioned d
In the case of a multi-orifice liquid jet recording head to which the rop-on-demand recording method is applied, particularly to a recording head which is applied to the recording method disclosed in Japanese Patent Application Laid-Open No. 54-59936, which enables high density recording. , its characteristics can be maximized.

The recording head of the present invention includes an orifice-side end portion having an orifice at its tip for ejecting liquid, a thermal energy acting portion where thermal energy acts on the liquid for ejecting the liquid, and a thermal energy acting portion where the liquid is applied to the acting portion. A plurality of liquid discharge parts having an inlet side end having an inlet for introducing the liquid; A common liquid chamber connected to the plurality of inlets and having a supply port for supplying liquid therein; If the volumes of the orifice side end, the thermal energy acting part, the inlet side end, and the common liquid chamber are V, , VH, V2, and V3, respectively, and the number of thermal energy acting parts is M, then V, /VH >0.32, V2/V8>
0.03 and V3/(VH·M)>16.

Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIGS. 1a and 1b are schematic explanatory views for conceptually explaining the features of the recording head of the present invention, in which a is a sectional view and b is a plan view. Only structures that make it clear are shown.

The recording head 101 includes an orifice-side end portion 103 having an orifice 102 at its tip for ejecting liquid, a thermal energy acting portion 104 which is a portion where thermal energy acts on the liquid for ejecting the liquid, and the acting portion. It has a liquid discharge part 107 composed of an inlet side end part 106 having an inlet row 05 for introducing liquid into the inlet side end part 106.
The inlet 105 communicates with the common liquid chamber 108, and the common liquid chamber 108 is provided with a supply port 109 for supplying liquid to the liquid chamber 108. It has a structure such that it is supplied to the chamber 108.

The common liquid chamber 108 has a plurality of inlets..., 105
-1,105-m, 105-n, 105-o,...
A plurality of thermal energy acting parts...,1
04-1, 104-m, 104-n, 104-o,...
..., and in response to recording signals input to these thermal energy acting parts, droplets are ejected and flying from the orifice 102 for each thermal energy acting part, and the ejected amount is The amount of liquid is quickly replenished from the common liquid chamber 108 to each thermal energy application section.

In the present invention, the volume of the orifice side end is set to V,
, when the volume of the thermal energy acting part is VH, the volume of the inlet side end is V2, and the number of thermal energy acting parts is M, V,/VH>0.32 due to the factual rhombus described later.
, V2/V,>0.03 and V3/(VH・M)>16
All of the above problems can be solved by designing and arranging the structure of each part so as to satisfy the following relationship.

In the following, the recording method of the present invention will be explained by citing the recording method applied to the recording method disclosed in Tokusekki No. 54-59936 in order to avoid complication of explanation. In order to facilitate understanding of the present invention, according to FIG.
The recording method described in Publication No. 159936 will be summarized.

In the second illustrated example, a recording liquid 203, generally called ink, introduced into a liquid chamber 202 from an introduction pipe 201 is instantaneously generated in response to heat generated by electricity in an electric/thermal converter 204 attached to the liquid chamber 202. causes a state change.

0 The converter 204 is connected to the electrode 2
Heat is generated in pulses by turning ON and OFF the electricity through the 05-1 and 205-2.

In this way, due to the change in the state of the recording liquid 203, an acting force is applied to the liquid 203 on the orifice 206 side, and as a result, the liquid 203 is ejected and scattered as droplets 207 from the orifice 206, causing paper, etc. Recorded village 210
Recording is done by adhering to the surface. Conversion body 20
4 is provided on a substrate 208, and a voltage from a power source 209 is applied according to the input of the 0 recording signal, heat is generated for conversion according to the input signal, and the recording corresponding to the input signal flies and adheres to the recording member 210. will be accomplished.

In addition, the size (diameter) of the liquid bottle 207 that is discharged from the orifice 206 and flies away is determined by the electric/thermal converter 2 as information.
04, the transfer efficiency of the thermal energy converted therein to the recording liquid 203, the conversion efficiency of the electricity/thermal converter 204, the diameter of the orifice 206, the inner diameter of the liquid chamber 202, the diameter of the orifice 206, etc. Transformer 2 from position
04, the acting force applied to the recording liquid 203,
the amount of liquid 203 affected, the specific heat of recording liquid 203,
Determined depending on thermal conductivity, boiling point, latent heat of vaporization, etc.

Therefore, any one of these elements that can be controlled
By changing one or more of the droplets 207
The size of the droplet can be easily controlled, and recording can be performed on the recording member 210 with any droplet diameter or spot diameter.

Incidentally, as the electric/thermal converter 204 in the illustrated example, a thermal print head (that is, a thermal head) widely used in the field of thermal recording is applied.

They are classified into thick film heads, thin film heads, and semiconductor heads depending on the manufacturing method, heating resistor, etc., but all of them can be used. However, especially when performing high-speed, high-resolution recording, it is currently desirable to use a thin film head. Figures 3a and 3b are for showing the multi-orifice recording head designed to achieve the present invention, in which a is a schematic assembly diagram and b is a diagram of the multi-orifice recording head when cut along the cutting line X'Y. FIG.

On an AI203 substrate 301 made of fine particles, Sio2 as a heat storage layer, HfB2 as a heater layer, and mountains as an electrode layer were sequentially layered horizontally using a thin film formation technique, and then selectively etched to form several types of patterns 302 as shown in the figure. Ta. These dimensions are as shown in Fig. 3b: heater part length h = 40, 80, 200 m, distance between orifice and heater part L = 20, 40, 80, 200, 500,
1000 m, distance between heater part and common liquid chamber 12 = 20,
40, 80, 200, 500 rm, distance between heater centers P = 50,100 m, W inside heater part = 40,80 m
150 sample substrates were manufactured with each value selected from the following dimensions. Separately, a cutter for a semiconductor chip scriber is equipped with a thin blade blade of 40 m and 80 m, respectively, to form a groove 303 in the heater and in accordance with the heater pitch.
Attach the same number of grooves to the glass plate with depth t=40,80 grooves 3
I made 04. The substrate 301 and the groove plate 304 are bonded with epoxy resin, and the depth 13=250,500,1000,
2000,4000 m, height S=100,200,5
00, 1000, 2000, and 4000 rm common liquid chamber forming blocks 305 were adhered with epoxy resin, and heater drive lead wires were connected to fabricate 150 experimental sample heads. The results of actual droplet ejection experiments using the sample head are shown in FIGS. 4 to 6.

These data values are the results obtained by microscopic observation under illumination of a light emitting element synchronized with the ejection applied voltage pulse. Figure 4 shows the relative ejected droplet volume (=term y3 y; ejected droplet radius) V using the common liquid chamber volume V3 as a parameter.
The relationship between R, the ratio of the heater front volume (orifice side end volume) V, and the heater part volume (energy acting part volume) VH is shown.

From the figure, log (V, /VH) = -0.52 {i.e. (V,
/VH)=0.316}. Moreover, it was found through experimental observation that the discharge becomes unstable in this region. This is thought to be mainly due to the fact that the liquid meniscus in the orifice after ejecting the liquid is unstable or no longer exists. Furthermore, FIG. 5 shows the relationship between the energy E of the electric signal applied to each ejected droplet and the volume ratio V2/V, using the heater section volume VH as a parameter. From Figure 5, log(
Deterioration of energy efficiency was observed in a region smaller than V2/V, )=-1.5. Also log(V2/V,)=
In the region of 0.9 or more, ejection instability appeared.

The former is considered to be due to a deterioration in energy efficiency due to an increase in the working volume of the discharge pressure generated in the heater section. The latter is considered to be caused by the incidental occurrence of conditions V and /VH 0.32 explained in FIG.

Therefore, from the above results shown in Figures 4 and 5, V, /VH
>0.32, V2/V, >0.03 were found to be conditions for improving recording characteristics. Furthermore, FIG. 6 shows the relationship between the ejected droplet volume, the common liquid chamber volume V3, and the heater section total volume VH·M (where M is the number of heaters) when all heaters are driven simultaneously, with V2 as a parameter.

From Figure 6 and experimental observation results {V3/(VH・M)}
When the value of is less than about 16, a decrease in the ejected droplet diameter and unstable ejection were observed. This is interpreted to be mainly due to a delay in liquid supply. From the above results, when designing a multi-orifice recording head, (1) V, /VH>0.32 (b) V2/V,>0.03 (m) V3/(VH・M)>16 It is clear that satisfying the following conditions is a requirement for providing good recording characteristics, and that the object of the present invention can be effectively achieved.

[Brief explanation of the drawing]

1A and 1B are schematic explanatory views for conceptually explaining the features of the recording head of the present invention, in which FIG. 1A is a cross-sectional view, and FIG. 1B is a plan view showing a part. FIG. 2 is a schematic explanatory diagram for outlining the recording method to which the recording head of the present invention is most effectively applied, and FIG. FIG. 3a is an assembled view, FIG. 3b is a sectional view taken along the dashed line X'Y in FIG. 3a, and FIG. 6 to 6 are graphs showing experimental results in the present invention. 101... Recording head, 102... Orifice, 103
... Orifice side end, 104 ... Energy acting part, 105 ... Inflow port, 106 ...
...Inlet side Oribe, 107 ...Liquid discharge part, 10
8... Common liquid chamber, 109... Supply V supply port, 1 10... Supply path. Tsutomu I Figure (Tsumi I Figure 2 Figure 3 (o) Figure 3) Figure 4 Hair Ta Figure Hair La Figure

Claims (1)

[Claims] 1. An orifice side end with an orifice at its tip for discharging liquid, a thermal energy acting part where thermal energy acts on the liquid to discharge the liquid, and a flow for introducing the liquid into the acting part. an inlet end having an inlet;
a common liquid chamber connected to each inlet and having a supply port for supplying liquid therein; The volumes of the inlet side end and common liquid chamber are respectively V_1, V_H,
When V_2, V_3 and the number of thermal energy acting parts are M, V_1/V_H>0.32, V_2/V_1>
0.03 and V_3/(V_5·M)>16.