JPH03184855A - Non-contact type recording device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is applied to recording engines such as printers and fax machines.

Prior Art Conventional technologies include US Pat.
There are publications such as Publication No. 553. U.S. Pat. No. 3,790,703 discloses an orifice and a switching heating means provided near the orifice, and a configuration in which the ejected ink is conveyed to the printing surface by an air flow.
L. If not, there is no specific setting of the air temperature that would cause the ink to solidify at the tip of the orifice and cause a clogging condition. Further, the configuration is not such that the pressurized gas acts sufficiently as a force for ejecting ink. moreover,
Not only does the ink ejected from the orifice scatter, resulting in poor resolution, but there is no mention of the relationship between the temperature and viscosity characteristics of the recording medium and the temperature of the pressurized gas.

For this reason, a large heating power is required, the printing characteristics change greatly depending on the environmental temperature conditions, and there are problems in reliability.

Furthermore, JP-A No. 63-57248 discloses that a heating means provided near the nozzle opening lowers the surface tension and viscosity of the ink, making it easier to eject the ink using electrostatic suction force. However, it does not utilize phase change ink.

Additionally, Japanese Patent Laid-Open No. 63-122553 discloses a multi-layer structure in which the printing speed is increased by ejecting the ink using electrostatic force and carrying it in the air during flight. It's not a thing.

The above two publications are improvements to the conventional electrostatic suction method, and do not utilize phase change as the discharge principle.
There are still problems with image quality deterioration such as clogging when left unused, ink smearing on the paper surface, and deformation of dot diameter. Furthermore, high voltage switching is required, which poses problems in terms of integration and cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and is particularly designed to enable color printing and digital recording in the recording engine of copiers, printers, etc. The object is to provide a recording device that is advantageous for recording. Furthermore, since direct image formation is possible with non-contact recording, the durability and reliability of the apparatus are increased, and a small and compact recording apparatus becomes possible.

In addition, the ink utilizes phase change and fundamentally solves the major problem of various methods using conventional water-based inks, such as dry clogging when left unused. Furthermore, it is an object of the present invention to theoretically solve the reliability problem of image quality deterioration due to changes in ejection direction due to paper dust or the like adhering to the nozzle surface.

In addition, a heating heater is provided only in the lower part of the ink area after injection is turned off, and the heater surface area exposed to air is made as small as possible to suppress heat loss during heating. Another object of the present invention is to provide a configuration in which the ejected recording medium is sufficiently placed in the gas flow to obtain a high-resolution image without spreading the printed dots.

Furthermore, the aim is to achieve high speed by increasing the responsiveness of the rise and fall of ejected ink and to improve the cutting of ink when ejection stops, and at the same time to obtain high resolution image quality by suppressing the dispersion of ink during flight. shall be.

Aoi Nee Kai.

In order to achieve the above objects, the present invention provides (1) a non-contact recording device using high-temperature melting ink that is solid at room temperature and melts when heated, and in which an ink discharge nozzle or slit opening is connected to a gas flow path; is set, solidifies the ejection port ink with a gas flow, and records by controlling the ink melting by the ejection section heating means, which pressurizes the ink supplied for ejection and synchronizes with the control frequency of the ejection section heating means. (2) In a non-contact recording device using high-temperature melting ink that is solid at room temperature and melts when heated, an ink discharge nozzle or slit opening is connected to the gas flow path. This is a device that records by setting the ejection port, solidifying the ink with a gas flow, and controlling the melting of the ink by the ejection portion heating means. The present invention is characterized in that it provides a change in electric field intensity that is synchronized with the control frequency of the discharge section heating means. An explanation will be given below based on one embodiment of the present invention.

Phase-changing high-temperature melting ink used here (recording medium)
is a substance whose main component is wax etc., which solidifies at least at room temperature and has a melting point above room temperature, such as:
Any property is acceptable as long as it melts at 50° C. or higher and reduces viscosity.

As an example, the characteristics of a recording medium that exhibits viscosity changes with respect to temperature are shown in FIG. At room temperature below 50℃~60℃, it will solidify (A area), but at high temperature above 80℃, it will become 500cp.
The liquid becomes a low viscosity liquid (region C) with a sufficiently low resistance for ejection. In addition, the intermediate region (B region) has sufficient viscosity to be supplied to the discharge port, and PreHea at a temperature at least equal to or higher than this B region
It will be a good thing if you do it.

The recording principle using the above characteristics of the recording medium will be described below. A gas flow such as air is caused to flow continuously at a speed of, for example, LoI/s or higher.

On the other hand, heating switching is performed to reduce the fluid resistance at the ejection port of the slit or nozzle flow path, thereby reducing the viscosity of the high-temperature melting ink whose main component is wax or the like. Then, due to the liquid level pressure difference or pressurization between the ink tank side and the frictional stress acting on the gas flow wall surface, the ink is ejected into the air.

In general, the wall pressure Pa under a steady flow of an ideal fluid without considering compressibility and viscosity is: Pa=P-1/2 ・pV Where, P: Total pressure of the upper gas flow ρ: Density of gas ■=Flow velocity of the gas flow, and if the gas flow velocity V is faster, the wall pressure P compared to the total pressure P
a becomes a small value. When this Pa is smaller than the pressure from the ink tank side, and furthermore, the pressure applied to the supplied ink is greater than the pressure loss due to viscosity on the wall of the supply pipe and the discharge port into the gas flow. ,
Ink will be ejected. Further, frictional stress corresponding to the gas flow velocity gradient also acts as an ejection force and a transport flying force on the ink to be ejected into the gas flow.

As described above, by energizing the heater near the nozzle or slit, the temperature reaches a high temperature of, for example, 150 to 300°C, and the ink, which has a low viscosity of 100 cp or less, is continuously ejected while the heater is energized. It turns out.

Then, it accelerates and flies in the gas flow, adheres to the paper surface, and then cools and solidifies. Here, the flow rate of the gas flow is set to 10~
By flowing at 100 m/s, several liters are deposited on the recording medium at the ejection port.
Negative pressure values of 0.0 g to several 100 g are easily generated.

FIG. 5 is a system configuration diagram of a non-contact recording apparatus according to the present invention, in which 1 is a preheater, 2 is an ink tank (
3 is a pressure pump, 4 is a heating drive terminal, 5 is a squeeze plate for recovering the air that collided with the printing surface 8- Laminar flow, 6 The filter 7 is a heat insulating plate, 8 is a temperature detection terminal, 9 is a temperature control section, 10 is a head with a built-in driver, 11 is a recording paper, and 14 is an ink pressure control valve. In particular, when configuring a color system, it is necessary to place the line heads close together and downsize. At this time,
When gas flows having a flow velocity of 10 to 100 m/s merge with each other, noise is generated and the laminar flow is disturbed, making the adhesion of the printing surface of the recording medium unstable. Therefore, gas flow recovery means 5 is provided between the head units and on the printing surface. This recovered gas flow from the printing surface is connected to a pressure pump 3 via a filter 6 with a diameter of several μm to absorb it.

Further, both the gas flow recovery system and the pressurized supply system are configured to have a heat insulating structure. The temperature of this circulating gas flow is 100° C. or less, and recording media that can be set to about 50° C., for example, are common. Therefore, the heat insulating material 7 does not require any special material, such as resin material with porous chambers, rubber material, etc.
Glass cotton or fibrous material may be used.

9- Specifically, the pipe line is mainly composed of calcium silicate, basic magnesium carbonate, caposite, asbestos, foam glass, hard polyurethane, etc. Although both ends of the preheater that covers the entire recording head are open, both ends are actually sealed.

In the system shown in FIG. 5, the temperature of the ink supplied to the ink ejection port by Pre Heat is as follows.

If the melting temperature is such that the ink becomes fluid, or if the pressure is applied from the tank side of the supplied ink, it is not necessary to completely melt the ink, but it is sufficient to have a temperature close to the melting point of one of several inks. Although the pre-heat temperature is low, the energy loss is small, and there is a large degree of freedom in selecting the structure and materials, and costs can be reduced.

In order to create a configuration in which ink is not ejected from the ink ejection port when the switching heater is turned off, the supply temperature of the gas flow is set below the ink melting point temperature, and only the ink at the ejection port is cooled by the gas flow flowing over the ink ejection port. Pre
The aim is to lower the temperature below the Heat temperature, increase the viscosity of the 0- ink, and increase the fluid resistance for ejection.

FIG. 6 shows a configuration in which the gas flow that carries the ejected ink to the printing surface is recovered, and a system in which the gas is circulated through a pressurizing pump has the advantage of less power loss. In the figure, 12 is a gas flow recovery path formed by a squeeze plate 5 close to the printing surface (recording paper) 11, and 13 is a head. This is to collect the mist that bounces off the printing surface or the paper dust adhering to the printing paper, and the problem with conventional inkjet is that paper dust and other dust adheres to the nozzle surface. It is possible to solve the problem of image quality disturbance due to clogging due to jetting and changes in the jetting direction.

1 and 2 are configuration diagrams for explaining an embodiment of the head section of the non-contact recording apparatus according to the present invention, FIG. 1 is an enlarged view of the ejection port of the head section, and FIG. , is a sectional view of the head portion. In the figure, 21 is a common liquid chamber, 23 is a gas flow path, and 2
4 is a switching heater, 25 is a heater for paste pre-1~, 26 is a surface member, 27 is a heat insulating material, 28 is an aluminum material, 29 is an alumina substrate, 30 is a driver mounting board,
31 is a holding member, 32 is a gas flow path forming member, 33 is ink, 34 is a diaphragm, and 35 is PZT.

For the surface member 26, a material with high temperature conductivity and excellent heat resistance is used. For example, AQ, Afi alloy,
These include dense alumina, sapphire, spinel, silicon carbide, silicon nitride, and cermet.

Furthermore, the heat insulating material 27 is made of a material with low thermal conductivity. Examples include glasses such as quartz glass and soda glass, and ceramics such as porous alumina, forsterite, steatite, zircon, cordierite, mullite, and zirconia.

First, pressurized air of 0, 1-0, 2 kg/an is passed through the air flow path 23 (slit @ 50 to 100 μm).
) to create an air flow of at least 50 m/s. The preheating heater 25 provided in the ink tank and the common liquid chamber 21 heats the ink to be supplied to the ejection portion above its melting point and turns it into a liquid phase. moreover.

Supply ink at P=200 to 1000 g/c using a pump output that pressurizes the supply air or a pressurizing pump provided separately.
Pressure is applied to s2. This pressure value is determined by the ink ejection slit width and ink viscosity. Then, pressure fluctuations are applied to the ink supplied to the pressurizing unit 1 composed of the diaphragm 34 and PZT 35 provided on the back side of the common liquid chamber 21 shown in the embodiment of the present invention.

Figures 3 (a), (b) and 4 (a), (b) are diagrams showing the drive timing of the switching heater of the discharge section according to the pressure fluctuation of the supplied ink, where P is the static pressure value of the ink, and v). I indicates the voltage applied to the heater, and TH indicates the heater temperature. In terms of operation, the pressure peak value and the peak value of the heater temperature are almost synchronized. Furthermore, the ink pressure is lowered before the ink temperature decreases, thereby eliminating ink remaining on the front surface of the slit portion after ejection.

It was confirmed that applying a pulsation of 20 to 30% or more of the static pressure value P as pressure fluctuation is effective in increasing the speed of ink ejection and in reducing ink shortage. The diaphragm 34 of the pressure unit is 5
Unimorph PZT on 0-200μm thick SUS plate
35 are glued together, and the arrangement direction is from 1 to 2 to 3.
13 rectangular PZT plates are continuously bonded at a book pitch and simultaneously driven synchronously to give pressure fluctuations. In FIG. 4, the configuration is such that a sinusoidal pressure fluctuation is applied up to a negative pressure value, and the heater opening operation is selectively applied once every two periods.

FIG. 7 is a diagram showing another embodiment of the head section of the non-contact recording apparatus according to the present invention, in which an electrostatic field is applied as a bias, and an electrode is provided on the end surface of the surface member constituting the ink discharge slit 1. It is provided by sputtering, vapor deposition, etc. In the figure, 36 is an ejection port electrode, 37 is a printing surface electrode, 38 is paper, and other parts having the same functions as in FIG. 1 are given the same reference numbers as in FIG. 1. In this case, the surface member is made of polyimide to cool and solidify the ink.

It is an insulating, highly thermally conductive member provided on a heat insulating plate such as glass. Suitable materials include ceramics such as aluminum nitride, silicon carbide, and alumina. Also, 0.
An electrode of about 1 to 2 mm is set on the surface of a platen (insulating material such as rubber material) provided at 5 to 1 + n + n points, and a voltage pulse is applied between it and the slit electrode to generate static electricity for ink ejection. This is a configuration in which the suction force is generated as a bias 14. If the applied voltage is about 500 to IKV, it will act as a pie scan.

FIGS. 8(a) and 8(b) are diagrams showing the electrostatic field and drive timing of the discharge section heater in the embodiment shown in FIG. 7. E represents the electrostatic field, VH represents the voltage applied to the heater, and TH represents the heater temperature. An example is shown in which the slit side electrode is grounded and the platen side electrode is set to 10 potentials. The timing for turning off the electrostatic field is near the peak value of the heater temperature. Note that the slit plate constituting the air flow path is made of an insulating material such as glass or alumina. Note that the slit side electrode may be a common solid electrode in the dot array direction, but it is also possible to have electrodes divided into the same pitch as the switching heater array pitch, electrically connected at the rear end, and driven simultaneously. is more effective.

Kazuo Toyo As is clear from the above explanation, the present invention has the following effects.

(1) Although the ink ejection force is given by the back pressure of the supplied ink and the air flow, the responsiveness of ejection rise and fall is accelerated by the pressure fluctuation component, and the ink at the tip of the ink ejection slit after the heater is turned off. There is no residue, and high speed and high reliability can be achieved at the same time.

(2) Since electrostatic suction force is applied as a bias to the ink ejection force, it increases the responsiveness of ink ejection, eliminates residual ink after the ink runs out, and further suppresses ink diffusion during flight. , it becomes possible to improve high resolution.

[Brief explanation of drawings]

1 and 2 are configuration diagrams for explaining an embodiment of the head section of the non-contact recording apparatus according to the present invention, FIG. 1 is an enlarged view of the ejection port of the head section, and FIG. , a sectional view of the head section, FIGS. 3 and 4 are diagrams showing ink pressure and drive timing of the ejection section heater, FIG. 5 is a system configuration diagram of the non-contact recording apparatus according to the present invention, and FIG. The figure shows a configuration for recovering the gas flow that carries the ejected ink to the printing surface, FIG. 7 shows another embodiment of the head section of the non-contact recording device according to the present invention, and FIG. , a diagram showing the electrostatic field and drive timing of the discharge part heater in other embodiments,
FIG. 9 is a diagram showing the characteristics of viscosity change with respect to temperature of a recording medium. 21... Common liquid chamber, 23... Gas flow path, 24...
Switching heater, 25... Heater for paste preheating, 26... Surface member, 27... Heat insulating material, 28...
... Aluminum material, 29 ... Alumina substrate, 30 ... Driver mounting board, 31 ... Holding member, 32 ... Gas flow path forming member, 33 ... Ink, 34 ... Vibration plate, 35...PZT.

Claims (1)

[Claims] 1. In a non-contact recording device using high-temperature melting ink that is solid at room temperature and melts when heated, an ink discharge nozzle or slit opening is set in the gas flow path,
A device that solidifies ejection port ink with a gas flow and records by controlling melting of the ink by an ejection portion heating means, which pressurizes the ink supplied for ejection and has pressure fluctuations synchronized with a control frequency of the ejection portion heating means. A non-contact recording device characterized by giving. 2. In a non-contact recording device using high-temperature melting ink that is solid at room temperature and melts when heated, an ink discharge nozzle or slit opening is set in the gas flow path,
An apparatus for recording by solidifying ink at the ejection port with a gas flow and controlling melting of the ink by a ejection portion heating means, which applies an electrostatic field between an electrode provided on the ink ejection portion and an electrode provided on the printing surface side, A non-contact recording device characterized in that the electric field intensity changes in synchronization with the control frequency of the ejection section heating means.