JP2001010058A - Ink jet recording head and method for ink jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To foam and discharge ink by a laser light without changing a discharge amount. SOLUTION: A laser light 18 of a TM mode is brought into a total reflecting prism 14 so that an angle of incidence to an interface between an ink 12 and the total reflecting prism 14 is smaller than an angle of total reflection when the ink 12 is a liquid phase and is not smaller than the angle of total reflection when the ink 12 is a gas phase. The laser light 18 passes the total reflecting prism 14 to heat the ink 12 while the ink 12 is the liquid phase. When the ink 12 changes to the gas phase because of the heating, the laser light is totally reflected, when the photothermal conversion is stopped. An energy of a minimum limit necessary for foaming the ink can be supplied to the ink 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink jet printer, and more particularly to an ink jet recording head and an ink jet recording method applied to a bubble jet printer utilizing a foaming phenomenon.

[0002]

2. Description of the Related Art Among ink jet recording methods, a generally used bubble jet recording method is such that ink in a liquid path is locally heated to a high temperature by a heating element to foam the ink, and the ink is formed by a high pressure generated at the time of foaming. Is extruded from a discharge hole and adheres to a recording medium such as recording paper. A recording head applied to the bubble jet recording method generally includes a minute structure such as a discharge hole, a liquid path, and a heating element provided as a part of the liquid path as an ink discharge energy generating section.

In order to be able to record a high-definition image by the ink jet recording method, a technique for ejecting the smallest possible ink droplets at a high density is required. For this purpose, it is basically important to form a fine liquid path and a fine heating element.

As a method of forming such a fine structure, there has been proposed a method of manufacturing a high-density recording head utilizing a photolithography technique utilizing the simplicity of the structure of a recording head of a bubble jet recording system (particularly). Kaiping 0
No. 8-156269).

As a method of ejecting minute ink droplets, there has been proposed a method of using a heating element having a larger heat generation amount at a center portion than at an end portion in order to adjust the ejection amount of the ink droplets (Japanese Patent Application Laid-Open (JP-A) No. 2002-110630). See JP-A-62-201254).

[0006] As a heating element in the bubble jet recording system, an electric-thermal energy converter (resistor) for converting electric energy into heat energy is generally used.
A method of directly heating the ink by irradiating the ink with a laser beam,
That is, a method of converting light energy into heat energy is also used. In this case, a light-to-heat energy conversion medium for converting light energy to heat energy separately from the ink may be used.

[0007]

In the conventional ink-jet recording method in which a liquid is foamed by light energy of a laser or the like (hereinafter referred to as a light-foaming ink-jet recording), a minimum and necessary light energy is required to foam the ink. Is used, a laser pulse having an appropriate pulse width is used.

However, the process in which a liquid is superheated and changes into a gas phase is a non-equilibrium transition process,
Fluctuation occurs in the timing of foaming of the liquid into bubbles.
For this reason, it is difficult to set a pulse width always suitable for foaming a liquid, and even if a laser having a specific pulse width is irradiated, sometimes excessive irradiation occurs, and at other times, the foaming occurs. There is no danger of inadequate irradiation.

Further, when the width of the laser pulse is extremely small, the pulse width of the laser pulse itself and the intensity of the laser are liable to fluctuate, and the discharge amount of the ink is fluctuated, which may cause deterioration in the quality of the recorded image. There is.

Accordingly, an object of the present invention is to provide a photo-foaming method capable of foaming ink without causing fluctuations in the ink ejection amount even when the foaming timing, the pulse width of the laser pulse, and the laser intensity fluctuate. It is an object of the present invention to provide a type ink jet recording head.

[0011]

In order to solve the above-mentioned problems, an ink jet recording head according to the present invention uses a TM (Transv) which heats ink in an ink jet recording head which discharges ink in ink holding means from a discharge hole.
laser light source that irradiates laser light in the erse Magnetic mode, and a total reflection prism that totally reflects the laser light at the interface with the ink. The angle of incidence of the laser light on the interface between the total reflection prism and the ink is It is characterized in that it is smaller than the total reflection angle when the ink is in a liquid phase, and is equal to or larger than the total reflection angle when the ink is in a gas phase.

The laser beam incident on the total reflection prism is
While the ink is in the liquid phase, it passes through the interface between the total reflection prism and the ink, and can be heated to foam the ink. On the other hand, after the ink foams and changes to the gas phase, the laser light is totally reflected at the interface between the total reflection prism and the ink, so that the ink is not excessively heated. That is, according to this configuration, it is possible to provide the necessary and minimum energy for foaming the ink by the laser light, and it is possible to suppress the fluctuation of the ink ejection amount.

When the refractive index of the total reflection prism is n _p , the refractive index of many gases can be approximated to 1.00, so that the total reflection angle of the TM mode laser light at the interface between the total reflection prism and the gas is arcsin (1.00 / n _p ), and since many liquids have a refractive index of 1.33 or more, the total reflection angle between the total reflection prism and the liquid is the total reflection angle of water arcsin (1.33 /
n _p ) or more. Therefore, the incident angle of the TM mode laser light on the interface between the total reflection prism and the ink is arcsin
The effect of the present invention can be realized by setting the angle to be equal to or more than (1.00 / n _p ) and smaller than arcsin (1.33 / n _p ).

In the ink jet recording head according to the present invention, it is necessary to dispose the total reflection prism in a direction substantially perpendicular to the total reflection surface (the interface between the ink and the total reflection prism).
A plurality of discharge holes cannot be formed in a direction substantially parallel to the total reflection surface, and the discharge holes cannot be arranged in a direction substantially perpendicular to the total reflection surface. Therefore, if the ejection holes are formed in a direction substantially perpendicular to the total reflection surface, the ejection holes can be arranged in a plurality of directions in two directions orthogonal to each other in a plane substantially parallel to the total reflection surface. A plurality of lines arranged in a line can be arranged in parallel.

Further, in an ink jet recording head having a liquid passage communicating the ink holding means and the discharge hole, and having a total reflection surface on one surface of the liquid passage, the ink discharge hole is substantially parallel to the total reflection surface. When formed in an appropriate direction, one end of the liquid path in the longitudinal direction becomes a discharge hole, so that the discharge hole can be formed only by bonding the wall member that forms the liquid path, and a drilling process for forming the discharge hole is performed. Is easy to manufacture because it is unnecessary.

Since the total reflection prism has an obliquely cut surface, if the total reflection prism is a part of the wall surface constituting the ink holding means, the total reflection prism is fixed to prevent the ink from leaking. In such a case, it is necessary to take into consideration the use of a fixing member or a sealant, and the production becomes difficult. Therefore, when the total reflection prism is configured by combining two or more types of glass with a transparent or translucent liquid or solid layer, at least one of the bonded glasses has a rectangular parallelepiped shape not including an obliquely cut surface. can do. If this glass is used as a part of the wall surface constituting the ink holding means, an ink jet recording head can be manufactured by a normal manufacturing method in which a rectangular parallelepiped glass is bonded to form a liquid chamber, and mass production becomes easy.

The ink jet recording method according to the present invention comprises:
An ink jet recording method including a step of irradiating a TM mode laser beam to ink through a total reflection prism to heat, foam, and discharge the ink, wherein a laser is applied to an interface between the total reflection prism and the ink. The light incident angle is smaller than the total reflection angle when the ink is in a liquid phase and is equal to or larger than the total reflection angle when the ink is in a gas phase.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows Embodiment 1 of the present invention.
FIG. 3 is a schematic cross-sectional view showing the features of the inkjet recording head of FIG. As shown in the figure, the total reflection prism 14 and the substrates 19, 20, and 21 arranged so as to surround the prism constitute an ink holding unit 27 having the liquid path 10 and the liquid chamber 11. The liquid path 10 and the liquid chamber 11 are filled with ink 12. The ink 12 is, for example, a liquid ink containing water as a main component and containing a dye or a pigment that absorbs light. A discharge hole 22 communicating with the liquid path 10 is formed in the substrate 19 and the total reflection prism 14 is formed.
Are arranged at positions where the interface with the ink 12 faces the ejection hole 22. The total reflection prism 14 is a substrate 21
Are fixed by a prism fixing member 13 provided in the first position.

A laser light source 16 for heating the ink is provided outside the ink holding means 27, and a condenser lens and a polarizing plate 17 are provided in front of the laser light source 16.

Next, the recording operation of the ink jet recording head shown in FIG. 1 will be described. TM mode laser light 18 from a laser light source 16 via a condenser lens and a polarizing plate 17
Is applied to the total reflection prism 14. The irradiated laser beam 18 transmits through the total reflection prism 14 and heats the ink 12. The heated ink 12 foams, producing bubbles 24. At this time, the ink droplet 25 is ejected from the ejection hole 22 due to a rise in pressure at the time of bubbling. The recording operation is performed by attaching the ink droplets 25 thus ejected to a recording medium (not shown).

The ink jet recording head according to the present embodiment has a configuration in which ink droplets are ejected in a direction substantially perpendicular to the interface between the total reflection prism 14 and the ink 12. A plurality of ejection holes 22 are arranged at a fine pitch in a direction (a direction perpendicular to the paper surface of FIG. 1) to form a line. Note that a configuration in which a plurality of lines are arranged in the direction of the liquid path 10 (the left-right direction in FIG. 1) may be employed. Further, a head in which the lines of the ejection holes 22 are formed may be provided for each of the plurality of types of inks 12, and a plurality of these may be arranged and integrated to form a head for discharging the plurality of types of inks 12.

Next, a method for foaming the ink 12 in the ink jet recording head of the present embodiment will be described in detail with reference to FIG.

FIGS. 2A and 2B are cross-sectional views of a portion near the total reflection prism 14 of the ink jet recording head of FIG. 1, that is, a portion where light-heat energy conversion is performed. The state of is shown.

In this embodiment, the incident angle θ _in of the laser beam 18 on the interface between the total reflection prism and the ink is smaller than the total reflection angle θ _t when the ink 12 is in a liquid phase, and the ink is in a gas phase. _Is greater than or equal to the total reflection angle θ _tg .

The refractive index of the total reflection prism 14 is n_p,ink
When n is a liquid phase, the refractive index is n _lThen total reflection
Total reflection angle θ at the interface between prism 14 and ink 12
_tIs θ_t= Arcsin (n_l/ N_p) (Expression 1) On the other hand, when the ink 12 is in a gaseous phase,
Folding rate n_gThen, the total reflection angle θ in this case_tgIs θ_tg= Arcsin (n_g/ N_p) (Expression 2) Therefore, from Equations 1 and 2, the laser light 18
Incident angle θ_inIs arcsin (n_g/ N_p) ≦ θ_in <Arcsin (n_l/ N_p) (Equation 3)

For example, when the main component of the ink is water,
Since the refractive index of the liquid phase of water is 1.33 and the refractive index of the gas phase is 1.00,
According to Equation 3, the incident angle θ _in may be an angle that satisfies arcsin (1.00 / n _p ) ≦ θ _in <arcsin (1.33 / n _p ) (Equation 4).

In particular, as the total reflection prism 14, the refractive index
When 1.64 heavy flint glass is used, the incident angle θ _in
May be set to 42.9 ° ≦ θ _in <64.8 °.

Here, the refractive index of many gases such as water, argon, sulfur, carbon monoxide, chlorine, chloroform, oxygen, bromine, hydrogen, nitrogen, neon, helium, benzene and air can be approximated to 1.00. Many liquids, such as aniline, ethyl alcohol, glycerin, diethyl ether, carbon tetrachloride, diiodomethane, seda oil, paraffin oil, and benzene, have a refractive index of 1.33 or more for water. Is greater than or equal to the total reflection angle arcsin (1.33 / n _p ). Therefore, whatever the component of the ink, the incident angle θ _in of the laser beam 18 that satisfies Expression 4 may be used.

When the laser beam 18 is incident on the interface between the total reflection prism and the ink at such an incident angle θ _in , FIG.
As shown in (a), while the ink 12 is in the liquid phase, the laser light 18 passes through this surface, and the ink 12 can be heated. By heating, bubbles 24 are generated in the ink 12 as shown in FIG. 2B, and after the ink 12 in contact with the total reflection prism 14 becomes a gaseous phase, the laser beam 18 is totally scattered at the interface between the total reflection prism and the ink. The light is reflected and the heating of the ink 12 automatically stops.

As described above, according to the configuration of the present embodiment,
The laser beam 18 does not irradiate the ink 12 more than necessary. Therefore, if the pulse width of the laser beam 18 is made sufficiently long, the irradiation of the laser beam to the ink 12 will not be insufficient, and the irradiation will not be excessively made by increasing the pulse width. . That is, according to the present embodiment, the minimum and necessary energy for foaming can be applied to the ink 12, and the fluctuation of the energy applied to the ink 12 and the fluctuation of the foaming timing of the ink 12 causes the fluctuation of the ejection amount of the ink 12. Can be suppressed.

(Embodiment 2) FIG. 3 is a perspective sectional view showing features of an ink jet recording head according to Embodiment 2. In the figure, the same parts as those in the first embodiment are described.
The same reference numerals are given and the description is omitted. The ink jet recording head shown in FIG. 3 except that a total reflection prism is formed by using a prism in which two kinds of glasses 52 and 53 are bonded by a bonding layer 51 made of a transparent or translucent liquid or solid. This is almost the same as the first embodiment. Further, a total reflection prism may be formed of three or more types of glass by adding a bonding layer and glass.

Since the total reflection prism has an obliquely cut surface, the total reflection prism is connected to the ink holding means 2.
If it is a part of the wall constituting the wall 7, it is necessary to fix the wall and take a method for preventing the ink from leaking, which makes the production difficult. Therefore, when this total reflection prism is composed of two or more types of glasses 52 and 53 and a coupling layer 51,
Since only the rectangular parallelepiped glass 52 that does not include the obliquely cut surface may be disposed in the ink holding unit 27,
There is an advantage that manufacturing is simplified and mass production is easy.

The laser light source 16 can be driven by a driving mechanism (not shown) in the pitch direction of the discharge holes 22 (the direction of the arrow in FIG. 3) in parallel with the incident surface of the glass 53 on which the laser light 18 is incident. It moves according to the position of the discharge hole 22 to be made.

(Embodiment 3) FIG. 4 is a perspective sectional view showing the features of an ink jet recording head of Embodiment 3. In the figure, the same components as those in the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted. As shown in FIG. 6, the ink jet recording head of this embodiment has ejection holes 61 in a direction substantially parallel to the interface between the glass 52 and the ink 12.

As in this configuration, the glass 52 and the ink 1
In the method of ejecting ink droplets in a direction substantially parallel to the interface with the substrate 2, the ejection holes 61 do not need to be formed in the substrate 62, and the ejection holes 61 can be formed only by bonding the substrate 62, the glass 52, and the substrate 31. This has the effect of facilitating manufacture.

In this embodiment, the laser light sources 63 arranged in an array are used instead of the drivable laser light sources 16 in the second embodiment, and the light sources at positions corresponding to the ejection holes 61 for ejecting the ink 12 are used. Is irradiated with a laser beam 18.

[0038]

As described above, according to the present invention,
The laser beam is incident on the interface between the total reflection prism and the ink at an incident angle that is smaller than the total reflection angle when the ink is in the liquid phase and greater than or equal to the total reflection angle when the ink is in the gas phase, and heats the ink. The present invention provides a light-foaming type ink jet recording head that can foam ink without causing fluctuations in the ink ejection amount even when the foaming timing, the pulse width of the laser pulse, and the laser intensity fluctuate. can do.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an inkjet recording head according to a first embodiment.

FIG. 2 is a cross-sectional view of a portion near a total reflection prism 14 according to the first embodiment.

FIG. 3 is a schematic diagram of an inkjet recording head according to a second embodiment.

FIG. 4 is a schematic view of an inkjet recording head according to a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Liquid path 11 Liquid chamber 12 Ink 13 Prism fixing member 14 Total reflection prism 16 Laser light source 17 Lens and polarizing plate 18 Laser light 19, 20, 21, 31, 32, 62 Substrate 22, 61 Discharge hole 24 Bubbles 25 Ink droplet 27 Ink holding means 51 Coupling layer 52, 53 Glass 63 Array laser light source

Claims (6)

[Claims] An ink jet recording head for ejecting ink in an ink holding means from an ejection hole, a laser light source for irradiating a laser beam of TM (Transverse Magnetic) mode for heating the ink, and Having a total reflection prism that totally reflects at the interface of the laser beam, the incident angle of the laser beam to the interface between the total reflection prism and the ink is smaller than the total reflection angle when the ink is in a liquid phase, and An ink jet recording head having a total reflection angle or more when the ink is in a gaseous phase. 2. The method according to claim 1, wherein an incident angle of the laser beam on an interface between the total reflection prism and the ink is equal to or larger than arcsin (1.00 / n _p ) and smaller than arcsin (1.33 / n _p ). Inkjet recording head. 3. The ink jet recording head according to claim 1, wherein the ejection hole is formed in a direction substantially perpendicular to an interface between the total reflection prism and the ink. 4. The liquid holding means has a liquid passage communicating with the ejection hole, and a total reflection prism is disposed on one surface of the liquid passage, and the ejection hole is provided between the total reflection prism and the ink. 2. A hole is formed in a direction substantially parallel to the interface of
Or the inkjet recording head according to any one of 2. 5. The ink jet recording head according to claim 1, wherein the total reflection prism has a structure in which two or more types of glass are combined by a transparent or translucent liquid or solid layer. 6. An ink jet recording method, comprising: irradiating a TM mode laser beam to ink through a total reflection prism to heat, foam, and discharge the ink. The angle of incidence of the laser beam on the interface with the ink is smaller than the total reflection angle when the ink is in a liquid phase, and is equal to or greater than the total reflection angle when the ink is in a gas phase. Inkjet recording method.