JPS61219660A - Thermal ink jet recorder - Google Patents

Abstract

PURPOSE:To ensure that clogging of a nozzle does never occur and enable high-speed recording, by a method wherein a liquid ink is fed by an ink carrier having a multiplicity of holes, and the ink is ejected by a recording head. CONSTITUTION:Prior to printing, the ink carrier 1 is moved in the direction of an arrow A, whereby an ink is supplied into the holes 4 by an ink-supplying means 5, and the ink 4 is held in the holes 4. When an electric currents passed to a recording electrode 6 by the functions of a power source 8 and a recording electrode driving circuit 7, a recording current is passed through the path constituted of the electrode 6, the ink 11, a conductive layer 3 and a return electrode 9, when Joule heat is generated in the ink 11, whereby the temperature of the ink 11 is rapidly raised. Due to the rapid temperature rise, bumping of the ink 11 or rapid evolution and growth of a bubble occurs, thereby ejecting the ink to the open side, namely, toward a recording paper 10. An ink droplet 12 ejected from the hole 4 of the ink carrier 1 flies onto the paper 10, forming an ink image on the paper 10.

Description

[Detailed description of the invention] [Technical field of invention] Regarding equipment.

[Technical background of the invention and its problems]

Conventionally, this method was used as a thermal inkjet recording method that performs recording by selectively blowing ink away using heat.

There are the following methods. One of them is the formation of bubbles due to the heat generated by the piezoelectric element and heating resistance element installed in the nozzle chamber.
is generated instantaneously, and the pressure of the resulting bubble pushes the ink out of the oriice (or nozzle). When the heating is stopped, the bubble contracts and draws the ink back. There is a method (see Japanese Unexamined Patent Publication No. 56-9429) that performs recording by causing some of the ink to fly out without returning. This method is called an on-demand method in which ink is ejected only when necessary, and has the advantage of not wasting ink and recording speed is relatively high. However, on the other hand, the production of the recording head is complicated, such as drilling holes in the nozzles and arranging piezoelectric elements and heat-generating resistors in the ink chamber, and ink coagulation occurs when the equipment is stopped, resulting in clogging. The biggest problem with this is that it causes malfunctions, which is why printers using the ft-maru inkjet recording system have not become popular despite having the above-mentioned features.

On the other hand, an attempt was made to perform recording by spraying ink 11a without using such a nozzle, and a ratio recording device (Japanese Unexamined Patent Publication No. 51-132
036) has been disclosed.

In this method, a heating resistor element is provided below the surface of the ink liquid to perform rapid heating to generate bubbles, and the impact caused by the bursting of the bubbles causes ink droplets to fly from the surface of the liquid to perform recording. Although this method essentially does not cause the problem of ink clogging, it does cause environmental pollution (foul odors, etc.) due to ink evaporation, and there are many restrictions on the configuration of the device, and furthermore, there is a problem with ink clogging during transportation and movement. Many problems still remain, including spillage and the difficulty of maintaining a constant distance between the ink surface and the heat generating part in terms of image quality.

The new recording technology has the advantages of low recording energy like inkjet recording, the ability to record on rough surfaces, and ease of handling like thermal transfer. It was waiting for its appearance.

[Purpose of the invention]

The present invention has been made to meet the above-mentioned demands, and its object is to provide a liquid recording device in which liquid ink is transported using an ink carrier having multiple holes.

[A chest of inventions]

The present invention includes an ink carrier that holds and transports ink;
Joule heat supply means for selectively applying Joule heat to the next ink held by the ink carrier;
There is provided a thermal ink jet recording apparatus characterized in that recording is performed by applying Joule heat by the Joule heat supply means and ejecting ink from the ink carrier onto a recording medium.

〔Effect of the invention〕

According to the invention, no nozzles are used at all.

Nozzle clogging, which was a problem in the past, has almost never occurred, and even if it were to occur for some reason, it would have no effect on the position of the recorded image because multiple holes correspond to one recording pixel. There isn't.

Furthermore, since the ink or the ink carrier holding the ink is directly heated, high-speed recording is possible.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

The recording principle of this invention will be explained using FIG.

The ink carrier (1) has an insulating support (2) provided with a conductive layer (3). As the support (2), any material can be used as long as it has electrical insulation properties and is not immersed in ink, such as polyester, fluororesin, nylon, polypropylene, and polyide.

The conductive layer (3) is a metal vapor deposited film such as At, Ni, Cr, etc.
It may be a metal sparter film or a metal foil such as At, Ni, or Cu. The resistance value of the conductive layer (3) must be controlled to such an extent that this layer does not become a heat source, and a specific resistance of 102 Ω·m or less is desirable. Such characteristics can be easily achieved, for example, by providing At with a thickness of 1 μm. The ink carrier (1) has a large number of through holes (4).6 The size and hole density of the through holes (4) are determined by the thickness of the ink carrier (1), the required resolution, and the number of pixels per pixel. It is determined by K, such as whether to form the ink droplets using individual ink droplets. For example, if the thickness of the ink carrier is 15μ, and a resolution of 8 lines/ml 1l and 11 pixel points are formed with an average of 25 ink droplets, approximately 1 hole with a diameter of 20μ is formed.
The ink supply means (5) may be formed at a density of 0,000/-, and may be a porous material such as felt or sponge impregnated with ink, or a structure in which the ink carrier (1) is immersed in the ink. The recording electrode (6) is single needle or multi-stylus. Recording electrode drive circuit +7)
, 1! the source (8) is connected to the recording electrode (6);
The connection to the recording electrode (6) according to the recording signal? ! It controls the The return electrode (9) is grounded in contact with the conductive layer (3) of the ink carrier (1). Return electrode (
9) may be provided in one-to-one correspondence with the recording electrodes (6), or one return electrode (9) may be provided for a plurality of recording electrodes (6), but here, the former ( 1 to 1)
I will explain about it. The shape of this return electrode (9) is plate-like.
Brush-like.

Alternatively, any material shape may be used as long as it limits the return current, such as a rotatable drum shape. Recording paper a [is high-quality paper,
Papers such as medium-quality paper and PPC paper, as well as plastic sheets such as OHP paper, synthetic paper, and the like can be used.

Prior to printing, ink is supplied from the ink supply means (5) to the ML (4) by movement of the ink carrier (1) in the direction of arrow A, and the hole (4) holds all of the ink αl). When the recording electrode (6) is energized by the power supply (8) and the recording electrode drive circuit (7), a recording current is applied to the recording electrode (6).
The ink αυ flows along the path of the conductive layer (3) and the return electrode 9. At this time, gel heat is generated in the ink αυ.

The temperature of the ink αυ increases rapidly. Due to this rapid temperature rise, the ink α9 is in a bumping state or bubbles are rapidly generated and grown, so that the ink is ejected onto the open surface, that is, onto the recording paper αIK.

Ink droplets α ejected from the holes (4) of the ink carrier (1) fly onto the recording paper α1, forming an ink image on the recording paper α1. In order to facilitate understanding, FIG. 1 shows the recording current path for the ink on the left in contact with the recording electrode (6), while the ink on the right is shown flying. As expected from the above explanation, the specific resistance of the ink is limited to 10Ω.
It is desirable that the resistance be less than or equal to 10Ω, and more effective results can be obtained especially if it is less than or equal to 10Ω.

FIG. 2 is a basic configuration diagram of a serial printer having a recording section configured as shown in FIG. The ink carrier (1
) is a ribbon with a width of 51M, which is made by laminating a 4μ thick copper foil on a 20μ polyimide layer, and then forming holes with a diameter of about 150/- on the support. Ink carrier cassette (1
4) has two reels, and the ink carrier (1) is fully supplied from one reel and wound onto the other reel. In addition, the ink carrier cassera) (14 is removable and can be used repeatedly by turning it over.The recording head (1!9 has the above-mentioned recording electrode of 100μ0 with 125
24 elements in μ pitch.

The ink carrier (1) is distributed in the entire transverse direction.

This recording electrode is connected to the recording electrode drive circuit power supply as described above. The ink tank 1, which is an ink supply means, has a structure in which ink leaks out from the ink tank 1η storing ink.

The return electrode /ll is made of a gold α piece and is connected to the ground terminal of the power supply. The recording paper α0 is an A4 size PPC paper. Ql) is the platen row 2 and is a rubber roller. The carriage @ has a recording head (1S, an ink tank (
[e. The return electrode α■ and the ink carrier cassette aet are placed thereon so that it can be moved across the recording paper αI. The equipment is a step motor for driving platen row 2, +24)
is a step motor for driving the carriage. Next, the operation of this printer will be explained.

When the power is turned on to start the printer, the carriage is moved from the home position to the printing start position by the action of the step motor (c) for driving the carriage.

Moving. In conjunction with this movement of the carriage @, the ink carrier (1) moves from the ink tank αe toward the recording head Q9, and at the same time, this movement causes the ink carrier (
1) The hole (not shown) is filled with ink from the felt Q8, and the ink carrier (1) is newly filled with ink.
comes into contact with recording head +19. The recording electrodes are selectively driven in accordance with recording signals by the function K of a recording electrode drive circuit (not shown), and ink is ejected in accordance with the recording principle explained using FIG. By this ejection, the tertiary carriage object on which the first vertical line of characters is recorded is moved 125 μm in the right direction by the action of a step motor for driving the carriage. In conjunction with this movement, the ink carrier (1) moves 125 μ to the left, and the ink carrier (1) filled with ink again contacts the recording head ([5]).

The previous operation is repeated again, and the next column is recorded. Thereafter, this operation is repeated until the carriage object reaches the right end of the recording paper ELL or the print end position, and recording of one line is completed. After this, the carriage Q3 moves back to the printing start position by the action of the step motor for driving the carriage. During this time, the recording paper (11) is moved by the plowing of the step motor for driving the platen roller. The platen roller (Zl) rotates once and is fed by one line. Thereafter, this operation is repeated to complete printing of one page. The print quality obtained was of high quality with no missing dots, and the printing after being left for one month was the same as before the printing without missing any dots from the beginning. This is to ensure that one pixel is made up of multiple ink droplets (in this case, 4 to 9 on average), and to ensure that one hole does not become clogged and no pixel is missing. Conceivable. Also the recording energy that forms %1 pixel.

This is less than 9% compared to when a thermal head that indirectly heats the ink is used as a recording head.

[Other embodiments of the invention]

As described above, in the above embodiments, the ink carrier is composed of an insulating support and a conductive layer on the insulating support, but the present invention is not limited to this structure.

A first alternative embodiment will be described.

FIG. 3 is a diagram showing the configuration of the recording section of the serial printer. The ink carrier is provided with a conductive layer on a resistive support. As the resistant support (c),
For example, polyester, polycarbonate, or the like mixed with carbon powder or fine metal particles such as Ni or Cu is used. The conductive layer (5) contains At.

Metal vapor deposited film such as Ns, Or, sputtered film% or A
4. Use metal foil such as Ni or Cu. resistor,
The relationship between the specific resistance of the support (c) and the conductive layer is important.

It must be ensured that most of the Joule heat is generated in the support (1) when current is applied. The desired specific resistance of both can take an appropriate value depending on the thickness of the support (A) and the conductive layer (A), but as a support, % 10'
~108Ω/country, 102Ω/sub or less is desirable for the conductive layer (5), and the ink carrier (c) has many through holes (
The size and hole density of one through hole (to) provided with (to) are determined by the thickness of the ink carrier (c), the required resolution -
Determined by how many ink droplets form one pixel5 For example, the thickness of the ink carrier is 20μ, the required resolution is 6/■ One pixel is expressed with an average of 9 to 16 ink droplets. Then, it is sufficient to form 50 μ diameter pieces at a density of #100 pieces/-. In Figure 3, the same numbers as in Figure 2 represent the same things as in Figure 2, so the explanation will be omitted. The recording operation of the printer will be explained.

Prior to printing, ink is supplied from the ink supply means (5) to the hole (to) by moving the ink carrier (c) in the direction indicated by the arrow, and the hole (to) holds ink (11). When the recording electrode (6) is energized by the function of the recording electrode drive circuit (7), the recording current is applied to the resistive support region @ (area marked with an arrow) in contact with the recording electrode (6), and to the conductive region. It flows through the path of the laminar return path electrode (9). At this time, Joule heat is generated in the current passing region of the resistive support (to), and this heat rapidly heats the ink (11) in this region, causing the ink to be in a bumping state or due to the rapid generation and growth of bubbles. , ink Ql) is ejected from the open surface, that is, the ink surface facing the recording paper a, and becomes ink droplets (to) onto the recording paper (
1G, and an ink image is formed on the recording paper α. The ink used in this printer may be insulating or resistive.

Figure 2 shows an example of a serial printer in which the ink carrier is mixed with 1 part of carbon powder in polycarbonate, and 4 parts are placed on a resistive support with a volume resistance of 106 Ω/an and a thickness of 20 μm.
Fully laminated μ steel foil, with a density of approximately 100 holes/- with a diameter of 50μ
The recording head was formed as a ribbon with a width of 5 mm.
The recording electrodes at the µ port were changed to ones with 24 elements arranged in a vertical line at a pitch of 167 µ.

Nine configurations of serial printers. The print quality obtained with this printer is comparable to that obtained with the printer shown in FIG. 2, and is of high quality. Also.

- Although the recording energy for forming dots was inferior to that of the printer shown in FIG. 2, it was less than % of that of the printer using a thermal head as the recording head.

Next, a second other embodiment will be described.

FIG. 4 is a diagram showing the configuration of the recording section. The ink carrier c31) has a resistive conductor layer (b) formed on an insulating or resistive support (b). As the insulating support, a film of polyester, polycarbonate, nylon, polyide, or fluororesin can be used. Polyester as a resistant support.

Carbon powder%Ni on polycarbonate etc.

It is possible to mix fine metal particles such as Cu and At into the material. The resistive conductor layer (b) is made of polyester, polycarbonate, carbon powder, Ni, Cu, and A.
A metal thin film obtained by vapor deposition, sparking, etc. can be used. For this ink carrier of 0υ, it is important that the specific resistance of the resistive conductive layer is smaller than that of the support. The specific resistance of the resistive conductive layer (b) is 10'Ω.

It is desirable that the specific resistance of the support above the scratches is 1060.3 or less; however, when a metal thin film is used as a resistive conductive layer, care must be taken regarding its thickness. In other words, if it is too thick, it may not be possible to heat the ink sufficiently due to large heat diffusion, and its low resistance may require a large power supply capacity to drive the recording element with low voltage and large current. If the voltage is increased, there will be problems such as a decrease in the 8/N ratio of 0N-OFF/voltage.

It is desirable to use the gold W4 thin film of Ni, At, etc. with a thickness of 1 μm or less. The recording head (to) is integrally provided with a recording electrode (to) and a return electrode (to). The recording electrode (to) and the return electrode (to) may be provided in a one-to-one relationship.
However, a plurality of recording electrodes may be provided in relation to one return electrode. The recording electrode (to) is connected to a power source (8) via a recording electrode drive circuit (7) that controls energization according to the recording signal.
)It is connected to the. i The ninth return electrode (to) is the power supply (8)
and grounded. Next, the recording operation will be explained. Ink carrier l3 before printing
1) in the direction of arrow A, the ink supply means (5
) from hole c3? ) is supplied with ink and the hole (b) holds ink @t-. When the recording electrode (to) is energized by the action of the recording electrode drive circuit (to), a recording current flows between the recording electrode (to) and the return electrode (to), and this region generates heat due to Joule heat. Due to this heat generation, the ink between the recording pole and the return electrode is rapidly heated, causing a bumping state or rapid generation and growth of bubbles. Recording paper α, which is the open surface of Gη
Discharge toward. The ejected ink (to) is on recording paper 0Q
An ink image is formed on the surface.

A conceptual diagram of using this recording section in a serial printer is shown in FIG.

In the serial printer shown in Figure 4, the ink carrier (31)
is a polyester film with a width of 5 m and a thickness of 25 μm.
In this case, holes with a diameter of 50 μm were provided at a density of about 100 holes/− in a support body formed by α2 μ vapor deposition.

The magnetic recording head (to) is located parallel to the recording electrode, which has 1400 elements arranged in a vertical row of 24 elements at a pitch of 167μ, and is located 167μ away from the recording electrode (the end of the recording potential and the return path! pole). One return electrode having the same length as the recording electrode array of the K24 element is integrally molded. The character quality obtained by recording characters with this serial printer was of high quality, equivalent to that of the printer shown in FIG. Although the energy for forming dots was inferior to that of the printer shown in FIG. 2, it was less than % of that of the nine printers used in the thermal head recording head.

In the above embodiments, the ink carrier used was one in which a through hole was provided in the support, but a structure in which a recess was formed in the support as shown in FIG. 6 may also be used. FIG. 6(a) shows a resistive support 40 with a recess 41t and a conductive layer 42 provided on the open side of the recess. Since the thickness of the support at the bottom of the recess is sufficiently thinner than in the lateral direction, the bottom has low resistance and the recording current can flow across the bottom. Such an ink carrier is shown in FIG. It can be used as an ink carrier for the recording method according to the present invention shown in FIG. Figure 6 rb) has a recess 44f in the insulating or resistive support 43! ：The closed surface of the recess has a resistive conductive #45t-type structure, which can be used as an ink carrier according to Jin's invention shown in FIG. #￥6 When using the ink carrier shown in FIG. 6, it goes without saying that ink is supplied by the ink supply means from the open side of the recess.

As described above, various modifications and variations can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the recording principle of the recording method according to the present invention, FIG. 2 is a block diagram of a serial printer which is an embodiment of the present invention, and FIG. 3 is a diagram for explaining the recording principle of the recording method according to the present invention. FIG. 4 is a diagram illustrating another configuration example of the recording method according to the present invention and its recording principle, and FIG. 5 is a diagram illustrating another configuration example of the recording method according to the invention and its recording principle. FIG. 6 is a diagram showing a modification of the ink carrier used in the recording apparatus of the present invention. 1... Ink carrier, 5... Ink supply means 6.
...Recording electrode, 7...Recording electrode drive circuit 8.
...Power source, 9...Return electrode 10...Recording paper, Agent Patent attorney Kensuke Norichika (and one other person) lθ Figure 1 Figure 3 (cL) Figure 6 Figure 4

Claims (2)

[Claims] (1) It is equipped with an ink carrier that holds and conveys ink, and a Joule heat supply means that selectively applies Joule heat to the ink held by the ink carrier, and the Joule heat supply means provides Joule heat to the ink held by the ink carrier. A thermal inkjet recording apparatus characterized in that recording is performed by ejecting ink from the ink carrier onto a recording medium. (2) The thermal ink jet recording apparatus according to claim 1, wherein the Joule heat supply means comprises a recording electrode and a return electrode.