JPH0480044A - Thermal ink jet recorder - Google Patents

Abstract

PURPOSE:To enable a stabilized recording dot to be quickly formed by small energy by a method wherein a preheater is installed to an entry side of a perforated film of a thermal head. CONSTITUTION:A preheater 1 is located to an upstream side of a heating element 7 of a thermal head 3, and a perforated film 2 holding thermal molten ink in a through hole 6 is located on their surfaces. The thermal molten ink 4 is melted by heating with a heat roller 11, and is applied to the perforated film 2. Liquid thermal molten ink 4b on the surface of the perforated film 2 is scraped off with a scraper 5 and besides is made to fill an inside of the through hole 6 to become solid thermal molten ink 4a. The ink transferred near to the thermal head 3 is heated again with the preheater 1, and is varied in phase again to the liquid thermal molten ink 4b until it is transferred onto the heating element 7. After the fixed thermal molten ink 4a inside the through hole 6 is returned again to liquid with the preheater 1, it is heated with the heating element 7. Therefore, generation of the steam bubble and discharge of the ink occur stably, and quick recording can be performed by a small energy recording signal.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a thermal inkjet recording device.

[Conventional technology]

Conventionally, as a method of thermal inkjet recording, a perforated film having a large number of fine through-holes and holding heat-melting ink in the through-holes is run while in contact with a thermal head, and the film is printed onto the opposing recording paper. A method for recording images has been proposed.

The recording principle is as follows.

In other words, a perforated film filled with heat-melting ink and having a large number of fine through-holes is run while in contact with a thermal head, and when the thermal head is energized and generated according to a recording pattern, the ink melts and the ink further melts. The low boiling point components are vaporized to generate vapor bubbles, and the pressure of the bubbles causes ink to be ejected from the through holes. The jetted ink is
It reaches and adheres to the opposing recording paper across a small gap to form a recording spot.

In this recording method, the number of through holes through which ink is ejected to form a recording spot corresponding to one heating element is not fixed, and when the density of the through holes is smaller than 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 be affected. It is possible to perform highly reliable recording without causing any major trouble and without missing dots.

Furthermore, since hot-melt ink is used, it is easy to maintain and is less prone to clogging.

FIG. 3 shows the recording process in such a conventional example, and FIG. 4 shows the recording state.

[Problem to be solved by the invention]

In the conventional thermal inkjet recording device described above,
Heat roller 11. The solid heat-melting ink 4a filled into the through hole 6 by the scraper 5 and whose temperature has decreased is
Due to the decrease in volume associated with the phase change, it shrinks inside the through hole,
Since almost nothing is exposed on the back side of the perforated film that is in contact with the heating element 7 of the thermal head 3, even if the heating element 7 generates heat due to the recording signal, sufficient heat transfer does not take place, resulting in the generation of vapor bubbles and stable ink ejection. But it didn't happen (Figure 4).

In addition, since solid ink is melted and vaporized, it requires greater thermal energy for recording than when using liquid ink, which may damage the heating element of the thermal head and prevent the recording speed from increasing. There were some problems.

[Means to solve the problem]

In the present invention, a thermal head is provided opposite to the back surface of a perforated film having a large number of micropores, and a recording paper is opposed to the surface of this perforated film, and furthermore, the micropores are capable of ejecting water onto the recording paper. A thermal inkjet recording apparatus that retains hot melt ink is characterized in that a preheater is located on the perforated film entry side of the thermal head.

〔Example〕

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

FIG. 1 shows a recording process according to an embodiment of the present invention, and FIG. 2 shows a recording state according to the embodiment. The characteristic part is the preheater 1.

In the recording part in this embodiment, as shown in FIG. 2, a preheater 1 is installed upstream of the heating element 7 of the thermal head 3.
A perforated film 2 holding heat-melting ink in through-holes 6 is located on their surfaces. The hot melt ink 4 is heated and melted by a heat roller 11 and applied to the perforated film 2.

At the same time, the liquid heat-melting ink 4b on the surface of the perforated film 2 is scraped off by the scraper 5.

The solid heat-melting ink 4a is filled into the through-hole 6 (FIG. 2). This ink that has moved to the vicinity of the thermal head 3 is reheated by the preheater 1, and changes its phase again into liquid heat-melting ink 4b before moving onto the heating element 7.

When this ink 4b inside the through hole 6 is heated by the heating element 7, its low boiling point components boil at the interface between the two, forming vapor bubbles. The heating element 7 is energized and generates heat once a recording pattern is set by a recording signal circuit (not shown) of the control device 8. The liquid heat-melting ink 4b inside the through-hole 6 is pushed out from the through-hole 6 by self-generated vapor bubbles, flies as a heat-melt ink droplet 4C, adheres to and permeates the recording paper 9, and forms a recording dot 10.

The solid heat-melting ink 4a inside the through hole 6 is returned to liquid form by the preheater 1 and then heated by the heating element 7.
Steam bubble generation and ink ejection occur stably, and high-speed recording is possible with a low-energy recording signal.

〔Effect of the invention〕

As explained above, the present invention has the effect that stable recording dots can be formed quickly with low energy by installing a preheater on the perforated film entry side of the thermal head.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a diagram showing a recording process according to an embodiment of the present invention;
FIG. 2 is a diagram showing the recording state of the embodiment, FIG. 3 is a diagram showing the recording process of the conventional example, and FIG. 4 is a diagram showing the recording state. DESCRIPTION OF SYMBOLS 1... Preheater, 2... Perforated film, 3... Thermal head, 4... Heat-melting ink, 4a... Solid heat-melting ink, 4b... Liquid heat-melting ink, 4C...・Hot melt ink droplet, 5... scraper, 6... through hole,
7... Heat generating element, 8... Control device, 9... Recording paper, 10... Recording dots, 11... Heat roller.

Claims (1)

[Scope of Claims] A thermal head is disposed opposite to the back surface of a perforated film having a large number of micropores, and a recording paper is opposed to the surface of this perforated film, and furthermore, a thermal head is provided in the micropores to face the recording paper. A thermal inkjet recording device in which ejectable hot-melt ink is held, characterized in that a preheater is located on the perforated film entry side of the thermal head.