JPH02139246A - Thermal inkjet printer - Google Patents

Abstract

PURPOSE:To form a recording electrode with high density thereby to record with high resolution by providing a porous film formed of at least two layers, namely, a conductive porous layer and a resistive or an insulative porous layer, a recording electrode in contact with said porous film at the side of said resistive porous layer and a return electrode in contact with said porous film. CONSTITUTION:A photosensitive polyimide 1b is applied onto a thin plate 1a of nickel and then many patterns of holes are formed thereon through photolithography. Thereafter, the nickel is etched by using the patterns of holes as a resist pattern to form many through-holes 1c. Thus, a porous film 1 is obtained. Recording is carried out while the porous film 1 and a recording paper 5 are pressed each other and moved without slippage therebetween. When a recording electrode 2a is made conductive in accordance with a recording pattern, the current runs through a hot melt ink 6 in the through-holes 1c and nickel part 1a of the film 1 and a return electrode roller 3, with generating heat at the position of the hot melt ink. A part of the hot melt ink is accordingly melted and evaporated, and the rest of the ink which is melted and softened is pressed to the recording paper 5 for recording.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal inkjet image forming apparatus, and more particularly to a thermal inkjet image forming apparatus using a perforated film holding ink.

[Conventional technology]

Conventionally, as a method of thermal inkjet recording, a perforated film having a large number of fine through-holes and holding liquid ink in the through-holes is run while in contact with a thermal head, and is printed onto an opposing recording paper. A recording method has been proposed. The recording principle is as follows: A perforated film filled with liquid ink and having many fine through holes is run while in contact with a thermal head, and when the thermal head is energized and generated according to the recording pattern, the ink is The low boiling point components of the ink vaporize and generate vapor bubbles, and the pressure of the bubbles causes ink to be jetted from the through holes. The ejected ink reaches and adheres to the opposing recording paper across a small gap to form a recording spot.

In this recording method, the through holes through which ink is ejected to form a recording spot corresponding to one heating element are not fixedly determined, and moreover, when the density of the through holes is small compared to the recording density, Since one recording spot is made up of ink droplets ejected from multiple through holes, even if some of the through holes become clogged and ink cannot be ejected, the recording result will not change. It has the characteristics of being able to perform highly reliable recording without causing any major damage to the image and without missing any dots.

[Problem to be solved by the invention]

However, since the perforated film must be run in close contact with the thermal head, it is necessary to use a type of thermal head with heating elements formed on the end face, but the end face type thermal head has manufacturing constraints. The problem was that high-density products could not be made.

[Means to solve the problem]

The present invention provides a perforated film comprising at least two layers, a conductive porous layer and a resistive or insulating porous layer, a recording electrode in contact with the resistive porous layer side of the perforated film, and a perforated film. and a return electrode in contact with the return electrode.

[Effect]

According to the present invention, when the recording electrode is caused to run in contact with the resistive porous layer side of the porous film holding ink, and the recording electrode is energized according to the recording button, the resistive porous layer and , a current flows through the ink, through the conductive porous layer, and to the return electrode. Whether the current flows mainly through the low-structure porous layer or through the ink is determined by the resistivity of the resistive porous layer and the resistivity of the ink, but in either case, the recording current The nearby resistive porous body or the ink itself generates heat, and the low boiling point components of the ink vaporize, generating vapor bubbles and generating pressure.

In the case of ink that is liquid at room temperature, the pressure of the bubbles pushes out the ink filling the holes and flies it, reaching and adhering to the opposing recording paper across a small gap to form a recording spot. In addition, in the case of hot melt ink, which is solid at room temperature and softens or liquefies when heated, pressure forces the ink out of the holes and presses it against the recording paper that is in contact with the perforated film, causing it to stick. to form a recording spot.

〔Example〕

Examples of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention.
FIG. 2 schematically shows the recorded portion.

The perforated film l is made by coating a thin nickel plate 1a with photosensitive polyimide lb, forming a large number of hole battens by photolithography, and then using this as a resist batten, etching nickel to form a large number of through holes 1c. This is what I did. The recording head 2 is made by forming a recording electrode 2a on a flexible printed board, molding it with resin, and polishing the tip. is forcing it on. The return electrode roller 3 is in contact with the nickel side of the perforated film 1, and is pressed against it by the backup roller 4.

Recording head 2. Return electrode roller 3. The pull-up roller 4 is integrated and moves while pressing the perforated film 1 and the recording paper 5 to prevent them from slipping to perform recording. On the upstream side, hot melt ink is once melted by an ink applicator (not shown), and is applied to the through holes I of the perforated film L.
Filled with C.

When the recording electrode 2a is energized according to the recording button, the current flows through the current path of the hot melt ink 6 in the through hole IC of the perforated film 1, the nickel portion 1a, and the return electrode roller 3. The resistivity of hot melt ink is approximately 1
It is adjusted to the 0-2Ω mark, and the power consumption per unit is the highest in this route, so heat is generated at the hot melt ink part, and a part of the hot melt ink melts and further evaporates.
The remaining melted or softened portion is pressed against the recording paper 5, and recording is performed.

FIG. 3 shows another embodiment of the present invention, in which the porous film 11 is a resistive porous layer 11a.

This is a film in which a conductive porous layer 11b and a water-repellent porous layer 11C are laminated in this order, and liquid ink is supplied at an upstream portion (not shown). Water repellent porous layer 11c
Since the contact angle with respect to the liquid ink is large, the liquid ink 12 does not wet the water-repellent porous layer 11c, but is retained only on the resistive porous layer 11a and the conductive porous layer 11b, and does not wet the porous film 11. Even when the liquid ink 12 comes into contact with the recording paper 5, it does not stain the recording paper 5. When the recording electrode is energized, heat is generated within the resistive porous layer based on the same principle as in the previous example, and the pressure of the generated bubbles causes the liquid ink to pass through the water-repellent porous layer 11c and onto the recording paper. reached and recorded.

〔Effect of the invention〕

In this way, ink is held in a porous film consisting of at least two layers, a conductive porous layer and a resistive or insulating porous layer, and the resistive porous layer side of the porous film is brought into contact with the recording electrode. When the recording paper is run and current is applied to the recording electrodes according to the recording pattern, the recording electrodes can be formed in high density, allowing high resolution recording.Furthermore, by adhering the perforated film to the recording paper, even higher resolution can be achieved. It has the effect of being able to record.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, FIG. 2 is a sectional view showing a recording section thereof, and FIG. 3 is a sectional view schematically showing a recording section of another embodiment. 1...Perforated film, lFL...Nickel thin plate, ■b...Polyimide, 1c...
...Through hole, 2.Old...Recording head, 3.....Return electrode roller, 4.....Back roller, 5.
... Recording paper, 6 ... Hot melt ink, ll ... Porous film, 11a ...
...Resistive porous layer, llb...Conductive porous layer, 11c...Water-repellent porous layer, 12...
・Liquid ink. Agent Patent Attorney Susumu Uchihara

Claims (2)

[Claims] (1) a perforated film consisting of two layers, a conductive porous layer and a resistive or insulating porous layer, and a recording electrode in contact with the resistive or insulating porous layer side of the perforated film; A thermal inkjet printer comprising: a return electrode in contact with the porous film. (2) Claim (1) characterized in that the perforated film is composed of three layers in which a water-repellent porous layer, a conductive porous layer, and a resistive or insulating porous layer are laminated in this order. The thermal inkjet printer described.