JPH02263651A - Non-contact type recording device - Google Patents

Abstract

PURPOSE:To enhance responsiveness by adopting such a constitution that an ink jet nozzle or a slit opening direction is set at a specific angel with respect to a gas channel for carrying ink. CONSTITUTION:In a non-contact type recording device employing high temperature fusing ink which is solid at room temperature and fuses by heating, an ink jet nozzle or a slit opening direction is set at 90 deg. or below with respect to a gas flow travel-straight channel 23, a gas flow supply temperature is set at the ink melting point or below, and an ink supply temperature is approximate to the ink melding point or above the melting point. According to a recording signal, a heating means 24 provided on the ink jet nozzle or the slit part is controlled to jet out ink. Consequently, the stable on/off control of ink jetting is attainable inexpensively by establishing conditions where ink in the jet nozzle is cooled effectively, and a high responsiveness device can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION -1) ffJ The present invention relates to a recording device using a phase change recording medium such as wax, and is applied to, for example, a recording engine such as a copier, a printer, or a FAX.

Prior art related to JUL Xiang includes U.S. Pat.
There are publications such as Publication No. 553. U.S. Pat. No. 3,790,703 discloses an orifice, 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. However, when the heating means is not turned on, , 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 scum acts as a force for ejecting ink by t. Furthermore, 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.
A large heating power is required, printing characteristics change greatly depending on environmental temperature conditions, and there are problems with reliability.

Furthermore, JP-A No. 63-57248 discloses that the surface tension and viscosity of the ink are lowered by a heating means provided near the nozzle opening, and the ink is made easier to eject by electrostatic suction force. , which does not utilize phase change ink. In addition, Japanese Patent Application Laid-Open No. 122553/1983 uses electrostatic force to eject ink and increases the printing speed by placing it on air while flying, but does not disclose a multi-layer structure. However, it does not utilize phase change ink. The above two publications and publications are improvements to the conventional electrostatic suction method, and do not utilize phase change as the ejection principle. There remains the problem of deterioration of image quality, such as deformation of the diameter. Furthermore, high voltage switching is required, which poses problems in terms of integration and cost.

Conventional recording devices can be roughly divided into impact type and non-impact type, but the impact type has a big problem with noise, and as a result, there is a demand for a low-noise, maintenance-free, non-impact printer, especially as it is not popularized in the personal field. has been done. As a non-impact printer,
There are inkjet, thermal, and laser electrophotographic methods, but the inkjet method is considered promising because it is high-speed, prints on plain paper, and is maintenance-free. This inkjet method generally records by constantly ejecting a fixed amount of ink, and since the ink is a dye-based coloring material, the printing is especially clear, which is advantageous for color printing, and since it is non-contact, it has very low noise. It is characterized by its durable printing quality. There are various types of inkjet, such as the pressure cabling method, the charge control method, and the electric field suction method, but the common problems with these methods include assimilation and clogging when left unused for long periods of time, as well as contact between the recording surface and the nozzle surface, and paper dust from the recording surface. There is dirt adhering to the nozzle surface, etc.

1-The present invention was made in order to solve the above-mentioned drawbacks, and is particularly designed to enable colorization 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.

Another object of the present invention is to provide an efficient recording apparatus having a configuration that minimizes the energy applied for ink ejection.

Furthermore, the present invention aims to improve reliability by performing temperature control that enables reliable ink ejection control by ON/OFF control of a switching heater for ink ejection control, and in particular, ink temperature control in a steady state.

(1) In a non-contact recording device using high-temperature melting ink that is solid at room temperature and melts when heated, the present invention has the following objects: On the other hand, the opening direction of the ink discharge nozzle or slit is set to an angle of 90 degrees or less, the supply temperature of the gas flow is set to a temperature below the melting point of the ink, and the supply temperature of the ink is set to a temperature below the melting point of the ink. (2) ejecting the ink by setting the temperature near or above the melting point of the ink and controlling a heating means provided in the ink ejection nozzle or the slit portion according to a recording signal; (3) further comprising means for setting the supply temperature of body temperature near the upper limit of the operating environment temperature and controlling the temperature of the supply gas flow to the set temperature based on the output of the supply gas flow temperature detection means; For the gas flow that carried the ink to the printing surface, a means for collecting the gas flow and circulatingly supplying it to the pressurizing pump, a means for taking in outside air and circulatingly supplying it to the pressurizing pump, and a supply amount of each of the above. and a temperature control means that controls the temperature to a set temperature based on the output of the temperature detection means of the gas flow supplied to the ink ejection port. Hereinafter, the present invention will be explained based on examples. The phase-change, high-temperature melting ink used here is one whose main component is wax, etc., which solidifies at least at room temperature and has a melting point above room temperature. It is fine as long as it has the characteristics to do so.

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. Moreover, the viscosity in the middle (region B) is sufficient to be supplied to the discharge port, and it is sufficient to perform preheating at a temperature at least equal to or higher than region B.

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, 1O+/s or more.

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 ■: The flow velocity of the gas flow. If the gas flow velocity V increases, the wall pressure Pa becomes a smaller value compared to the total pressure P°. This Pa is smaller than the pressure from the ink tank side, and Ink will be ejected if a pressure greater than the pressure loss due to viscosity is applied to the supply pipe and the wall of the ejection port into the gas flow. On the other hand, frictional stress corresponding to the gas flow velocity gradient also acts as a discharge force and a conveyance flying force.

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.

FIG. 1 shows an example of the results of differential thermal analysis of ink used in the non-contact recording device of the present invention. This ink is an ink that is solid at room temperature and has one or more transition temperatures in the temperature range from room temperature to when it completely dissolves when it undergoes a phase transition from solid to liquid.

Room temperature is in the range of 5 to 35°C, and whether or not there is one or more transition temperatures from this temperature to the melting point can be easily determined by performing differential thermal analysis (DSC). can. That is, the temperature corresponding to the endothermic peak that appears in differential thermal analysis is the transition temperature. In FIG. 1, four endothermic peaks are shown, including the shoulder two. Having multiple transition temperatures as shown in this example is
When a vehicle is composed of a single compound,
Solid at room temperature with a partially fine crystal structure,
This is the case when the compound has a melting point in the range of 50 to 200°C and a glass transition point in the range from room temperature to the melting point. Examples of compounds that exhibit such properties are polyacrylic acid esters.

Examples include polyethylene oxide, ethylene vinyl acetate copolymer, and the like. Furthermore, when an ink vehicle is composed of a plurality of compounds, and two or more compounds having different melting points are mixed, a plurality of transition temperatures will appear.

Compounds used in the above ink include natural waxes such as lunaba wax, candelilla wax, spermaceti wax, beeswax, wood wax, and jojoba wax, higher alcohols such as tetracosanol and hexacosanol, and In addition to these esters, there are higher fatty acids and their esters.

The complete dissolution temperature at which the entire ink becomes fluid is a value higher than the transition temperature, which is the highest temperature.

FIG. 2 is a system configuration diagram of a non-contact recording apparatus according to the present invention, in which 1 is a preheater and 2 is an ink tank (
3 is a pressure pump, 4 is a heating drive terminal, 5 is a squeeze plate for collecting the gas flow that collides with the printing surface,
6 is a 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, if the gas flows having a flow velocity of 10 to 1000 m/s merge with each other, noise will be generated and the laminar flow will be disturbed, making the adhesion of the printing surface of the recording medium unstable. Therefore, a gas flow recovery means 5 is provided between the spatula 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.

Specifically, the pipes are 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. 2, the temperature of the ink supplied to the ink ejection port by Pre Heat is as follows.

If the melting temperature is set to fluidity, or the supply ink is pressurized from the tank side, it is not necessary to completely dissolve it (
It is sufficient if the temperature is close to the melting point of one of the 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.

3 and 4 are configuration diagrams of the head section of the present invention, in which 21 is a common liquid chamber, 22 is an upper plate, 23 is a gas flow path, and 2
4 is a switching heater, and 25 is a paste preheat heater. The recording material ejection slit is set at an angle of 90 degrees (FIG. 3) or less (FIG. 4) with respect to the gas flow path 23. Switching heater 0
In order to create a configuration in which ink is not ejected from the ink ejection port during F, 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. The aim is to lower the temperature, increase the viscosity of the ink, and increase the fluid resistance for ejection.

FIG. 5 shows the cooling temperature of the ink surface at the ejection port versus the gas flow supply temperature. The timing of the ink ejection port is 5.
Since it has a minute size of 0μ or less, the area in direct contact with the gas flow is small, and the cooling effect is not large. Therefore, it is preferable that the supply temperature of the gas flow be as low as possible, and stable discharge characteristics can be obtained by always controlling the temperature near the upper limit of the operating environment temperature. Even if the environmental temperature fluctuates, if the ink temperature at the ejection port is controlled to a constant temperature, the amount of heat applied to melt the ink by the switching heater for ejection will always be constant and stable ejection. Discharge loss slit width 30 μm, gas flow velocity 10
When the gas flow supply temperature is 0 m/s and the gas flow supply temperature is 35 to 40°C, the surface temperature of the ink at the ejection port decreases by 5°C. At this time, in a system using ink whose main component is paraffin,
Stable discharge characteristics were obtained.

FIG. 6 shows another embodiment of the invention with constant control of the gas flow supply hotbed. In the figure, 15 is an open pipe line, 16.
17 is a flow control valve, 18 is a filter, and 19 is a suction pipe. When controlling the gas flow supply temperature as described above, in the case of a configuration in which all the supplied air is taken in from the outside, electric power is required for heating up to the control temperature.

FIG. 7 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 pressure 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. However, in this case, heat is transferred from the head base, ink, etc. to the gas flow, and the temperature of the circulating gas flow gradually increases, making it impossible to control the gas flow temperature for cooling the ejection port ink. Furthermore, the temperature inside the device may also increase during operation, which may interfere with the temperature control described above. Therefore, as shown in Fig. 6, a flow rate control means for controlling the amount of recovered gas flow circulated in the pressurized air pump and a means for controlling the amount of outside air taken in and supplied to the pressurized pump are provided. The temperature of the supplied gas flow is controlled to be constant by controlling each of the flow rate control means based on the output of the temperature detection means of the gas flow supplied to the ink ejection port. In other words, when the temperature of the recovered and circulated gas flow exceeds the control temperature, the amount of outside air intake is increased, and when the temperature of the recovered gas flow decreases, the amount of outside air intake is decreased, thereby reducing the power loss of the entire system. It is possible to minimize it. Of course, when the operating environment temperature is as low as 5 to 10° C., there may be conditions in which the amount of outside air taken in is zero and the temperature is further controlled by means of heating the pressurized pump output gas flow.

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

(1) By setting the opening direction of the ink discharge nostle or slit at an angle of 90 degrees or less with respect to the ink transporting gas flow path, ink only in the opening is efficiently cooled, and By flowing a temperature-controlled gas flow and using a recording medium with temperature and viscosity characteristics that respond to the temperature, a recording method that is stable and responsive to changes in environmental conditions becomes possible.

(2) Stable ink ejection by setting the condition to have a large cooling effect on the ejection port ink by the supply gas flow, ○F
I? Control is possible, and in particular, the falling characteristic when turned off is improved, and a device with good responsiveness becomes possible.

(3) Power loss was minimized because the temperature of the supplied gas stream was controlled to be constant while the recovered gas stream was also recirculated. Stable ink ejection ON/OFF control is possible.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the results of differential thermal analysis of ink used in the inkjet recording device according to the present invention, FIG. 2 is a system configuration diagram of the non-contact recording device according to the present invention, and FIGS. 3 and 4 are diagrams showing the head Fig. 5 is a diagram showing the cooling temperature of the ink surface of the ejection port with respect to the gas flow supply temperature;
7 is a diagram showing another embodiment of the present invention in which the gas flow supply temperature is controlled to be constant; FIG. Figure 8 is. FIG. 3 is a diagram showing characteristics of viscosity change with respect to temperature of a recording medium. 1... Preheater, 2... Ink tank (C Nijiman. M: Magenta, Y: Yellow, B Ni Black). 3... Pressure pump, 4... Heating drive terminal, 5...
... squeeze board, 6... filter, 7... heat insulation board,
8...Temperature detection terminal, 9...Temperature determination section, 10.
...Head with built-in driver, 11...Recording paper, 12.
...Gas flow recovery path, 13...Head part, 14...
Ink pressure control valve. Fig. Time [minutes] Fig. Fig. Fig. Fig. Viscosity change characteristics with respect to temperature

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, the opening direction of the ink discharge nozzle or slit with respect to the straight flow path of the gas flow. set to an angle of 90 degrees or less,
The supply temperature of the gas flow is set to a temperature below the melting point of the ink, the supply temperature of the ink is set near or above the melting point of the ink, and a heating means provided at the ink discharge nozzle or slit portion is provided. Control according to the recording signal,
A non-contact recording device characterized by ejecting the ink. 2. It is characterized by having means for setting the supply temperature of the gas flow near the upper limit of the operating environment temperature, and controlling the temperature of the supply gas flow to the set temperature based on the output of the supply gas flow temperature detection means. The non-contact recording device according to claim 1. 3. Means for collecting the gas flow that carries the ink to the printing surface and supplying the gas to the pressurizing pump in circulation; means for taking in outside air and supplying the air in circulation to the pressurizing pump; 2. The non-contact recording device according to claim 1, further comprising: a control means for controlling the supply amount; and a temperature control means for controlling the temperature to a set temperature based on the output of the temperature detection means of the gas flow supplied to the ink ejection port. Device.