JPS60248357A - liquid jet 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] [Technical Field] The present invention relates to a liquid jet recording device that performs recording by discharging a liquid to form discharged droplets and attaching the droplets to a recording material such as paper, and in particular, The present invention relates to a liquid jet recording device that applies thermal energy to a liquid to form ejected droplets.

[Prior art]

The liquid jet recording method is a recording method that performs recording by forming ejected droplets of recording liquid using various methods and attaching the droplets to a recording material such as paper.

Among recording devices that apply this type of recording method, a type of liquid jet recording device that uses heat as energy to form ejected droplets is a device that has a structure suitable for creating a high-density multi-orifice recording head. can be mentioned.

Liquid jet recording devices that use heat as droplet ejection energy usually heat the recording liquid to give it a displacement that causes a rapid increase in deposition, and then
It has a droplet forming means for forming droplets of recording liquid ejected from the recording liquid, and an electrothermal energy conversion element (hereinafter referred to as a heater) that can generate heat and heat the recording liquid by applying an electric signal. Equipped with a recording head.

On the other hand, as the recording liquid used when recording with a liquid jet recording apparatus, an aqueous recording liquid is mainly used from the viewpoint of recording characteristics, safety, and the like. This aqueous recording liquid is generally formed from a recording agent component such as a pigment or dye, and a solvent component mainly consisting of water or water and a water-soluble organic solvent for dissolving or dispersing the recording agent component.

In the above-mentioned recording device that uses heat as droplet ejection energy and other recording devices that apply the droplet formation force method, an orifice (droplet ejection hole) installed at the tip of the nozzle from which the recording liquid is ejected is used. ) are often constantly opened to the outside air of the device, regardless of whether the device is driven or not.

Therefore, if recording is not performed for a long period of time, water or volatile organic matter, such as water or volatile organic Solvent components such as solvent evaporate from the orifice into the outside air, and recording agent components and solvent components that are difficult to volatilize remain in the recording liquid, increasing the viscosity of the recording liquid retained in this area, and as a result, the recording liquid Immediately after restarting recording, a droplet ejection failure is likely to occur in which droplets are not ejected even though an ejection signal is applied, and recording There is a problem in that defects occur in the initial printed portion of the image.

On the other hand, in order to obtain a good droplet ejection condition even when the viscosity of the recording liquid increases at low temperatures, the droplet ejection signal is not applied so that the temperature of the recording liquid can always be maintained within a predetermined range. JP-A-58-18-3E14 discloses a recording method in which the recording liquid is heated by constantly applying an electric signal to a heater at a level at which no border droplets are ejected.

However, even in a recording device employing this method, an electric signal is applied to the heater so that the recording liquid is always kept at a high temperature even during a relatively long recording pause or stop period. The solvent component in the recording liquid evaporates more easily, and the above-mentioned problem of droplet ejection failure during recording reprinting is more likely to occur. In addition, in this method, since the area around the heater is constantly heated, the durability of the surrounding parts of the heater may be impaired, or records may accumulate around the heater area during recording suspension periods. Changes in physical properties due to the heat of the liquid itself may occur, causing problems such as discoloration of the recording liquid or the formation of precipitates in the recording liquid, clogging the orifice and causing droplet ejection failure.

[Purpose of the invention]

The present invention was made in view of these problems, and mainly adjusts the viscosity of the recording liquid within a suitable range in order to always obtain a good droplet ejection condition during droplet ejection. To provide a liquid jet recording device which can always obtain a good and stable droplet discharge state even when restarting recording after a particularly long recording stop or stop period.

Another object of the present invention is to maintain good quality and stability at all times without reducing the durability of the parts surrounding the heater of the recording device, and without causing deterioration of the recording liquid stagnant near the heater when recording is stopped due to the influence of heat. It is an object of the present invention to provide a liquid jet recording device that can obtain a droplet ejection state that is as follows.

Another object of the present invention is to provide a liquid ejecting system that can always provide a good ejection condition by using a droplet forming means without the need for a special recording liquid heating means for adjusting the viscosity of the recording liquid in order to obtain a good ejection condition. An object of the present invention is to provide a liquid jet recording device that uses thermal energy to form droplets that can provide a stable droplet discharge state.

[Summary of the invention]

The above objects and other objects can be achieved by the present invention as follows.

That is, the liquid jet recording device of the present invention is a liquid jet recording device having an electrothermal energy converter that is used to apply an electric signal to heat the liquid and form flying droplets. comprising: a discharge signal generating means for causing the converter to discharge droplets; and a heating signal generating means for generating an electric signal applied to the electrothermal energy converter within a range in which droplets are not discharged. It is characterized by

The liquid jet recording apparatus of the present invention will be explained in detail below with reference to the drawings.

The recording apparatus of the present invention will be described below, taking as an example a liquid jet recording head that uses heat as energy for forming droplets.

FIG. 1 is a schematic diagram of a recording head section of an example of a liquid jet recording apparatus of the present invention, and FIG. 2 is a partially enlarged view of the vicinity of the nozzles of the recording head section of the apparatus shown in FIG.

1 is a supply tube that connects the main tank for recording liquid storage (not shown) and the sub-tank 2 that temporarily stores the recording liquid inside the recording head, and supplies the recording liquid from the main tank to the sub-tank; 3 is a supply tube (not shown) A suction tube connected to the recovery pump, 4 a supply pipe unit for supplying recording liquid from the sub-tank 2 to the liquid chamber 5, 6 a retainer for the supply pipe unit 4, and 7 shown in FIG. A nozzle portion in which a predetermined number of orifices (droplet ejection holes) 12 are arranged in the vertical direction, and 8 is a heater for applying thermal energy to the recording liquid in the liquid flow path 14 shown in FIG. 13 is an electric wiring section consisting of an FPC (flexible printed circuit) for applying an electric signal; 9 is a supply pipe unit 4, a liquid chamber 5, a nozzle section 7, a supply pipe holder 6, and an FPC:
8 is arranged, a base plate for supporting these, 10 a bushing for supporting the periphery of the nozzle part, 1
1 is a front plate.

In this example, a droplet forming means for forming droplets to be ejected from the orifice 12 and a liquid flow path 14 that communicates with the orifice 12 and has a portion where heat from the heater is applied to the recording liquid is configured. A liquid heating means is constituted by a filter 13 and an FPC 8 for applying an electric signal thereto as required. Also.

Although not specifically shown in the drawings, this device includes an ejection signal generation means for generating an electric signal applied to eject droplets, and an electric signal for heating the recording liquid, which will be described later. Heating signal generating means is provided for this purpose.

To perform recording using this device, first, from the main tank, via the supply tube 1 and the supply pipe unit 4,
The sub-tank 2, liquid chamber 5, and liquid flow path 14 are filled with recording liquid. Next, a recording signal, that is, an electric signal from the droplet ejection signal generating means is applied to the heater 13 by the FPC to energize the heater 13. As a result, heater 1
3 generates heat, thermal energy is applied to the recording liquid in the liquid flow path 14 near the heater 13, and bubbles are generated in the recording liquid with an instantaneous increase in the volume of the recording liquid at that part. occurs, the recording liquid located downstream of the heater 13 is ejected from the orifice 12, and droplets of the recording liquid are formed. Recording is performed by making droplets of the recording liquid adhere to a recording material such as paper that has been sent in front of the nozzle section 7.

In the liquid jet recording apparatus of the present invention, when recording is performed by the operation described in -H, that is, immediately before applying electricity No. 45 to the heater 13 for ejecting droplets used for recording, the recording A liquid heating signal is applied.

The recording liquid heating signal applied in the apparatus of the present invention is
This is an electric signal for heating the recording liquid by the heater 13 to a temperature at which a suitable viscosity of the recording liquid is obtained in order to obtain a good recording liquid ejection condition to such an extent that no droplets are ejected. generated.

The heating time for the recording liquid by the heater 13, which generates heat due to the application of the heating electric signal, can be applied within the range that can heat the recording liquid to the predetermined temperature, and in the shortest possible time. preferable.

By heating the recording liquid over a short heating time, the heater 13 and the components surrounding the heater are less likely to be affected by heat, which can cause deterioration, thereby extending the lifespan of these components. It also minimizes the diffusion of heat from the heater to the area around the heater, which reduces the amount of recording liquid to be heated and allows the entire recording liquid in the liquid flow path or in the liquid chamber to be heated. This is because it is possible to eliminate the influence of heat, and furthermore, it is possible to prevent the accelerated evaporation of part of the solvent component of the recording liquid from the orifice due to a long heating time. The heating time of the recording liquid is appropriately selected depending on various conditions such as temperature characteristics such as heat capacity of the recording liquid, structure of the apparatus, and temperature suitable for the recording liquid to be ejected.

Taking these requirements into consideration, when applying a heating electric signal in the liquid jet recording device of the present invention, the application conditions of the droplet ejection signal in the device and the temperature characteristics of the recording liquid used are In particular, depending on various conditions such as the temperature characteristics of the viscosity of the recording liquid, changes in the viscosity of the recording liquid during recording pauses or stops, etc., the heater is controlled individually to predetermined values such as the voltage, frequency, pulse l, etc. It is sufficient to apply it to .

Various methods can be applied to control the electrical signal and convert it into an electrical signal for heating, but among these, the following method can be easily carried out using an electrical signal circuit built into the recording device. For example, it is possible to make the ejection signal generation means also serve as the heating electric signal generation means, and to control the electric signal from the ejection signal generation means as follows to generate the heating electric signal.

That is, the relationship between the frequency voltage, pulse width, and heating temperature in the applied electric signal is, for example, when the applied voltage is 23.5 V, the pulse l is 5 gs, and various frequencies (
Figure 3 shows the change in temperature over time when 10 kHz, 5 kHz, 2 kHz) is applied to the heater. b) Lower the voltage and increase the frequency of the droplet ejection signal used in that device; C) The pulse of the droplet ejection signal used in that device. Methods such as lowering both the width and voltage and increasing the frequency can be applied to achieve the objective listed in L.

The specific values when applying such a method vary depending on the physical properties of the recording liquid used, the characteristics of the device, etc., and cannot be specified in part, but usually in the case of method a, , the pulse width of the electric signal for heating is preferably about 1/125 to 1/100 of the pulse width of the signal for ejecting droplets,
More preferably, it is about 11゛2 to l/20. In the case of the method, the voltage of the electric signal for heating is
Preferably 1/1.25 to 1/ of the voltage of the droplet ejection signal.
The frequency is about 10, more preferably about 1/1.4 to 1/2.4, and the frequency of the electric signal for heating is 1, and the frequency of the droplet ejection signal is preferably about 2 to 100 times, more preferably 5.
It is desirable to make it about 50 times. In the case of method C, the voltage of the electric signal for heating is preferably about 1/1.25 to 1/10, more preferably about 1/1.4 to 1/2, of the voltage of the droplet ejection signal. The pulse width of the electric signal for heating is preferably about 1/1.25 to 1/100, more preferably 1/2 of the pulse width of the signal for ejecting droplets.
~l/20 or so, and furthermore, the frequency of the heating electric signal is
It is desirable that the frequency is preferably about 2 to 100 times, more preferably about 5 to 50 times, the frequency of the droplet ejection signal.

Note that the ejection signal generating means and the heating electric signal generating means may be provided independently.

The heating electric signal applied in the apparatus of the present invention may be always applied immediately before the droplet ejection signal is applied to the heater, and the recording apparatus may be powered on for a certain period of time. recording is paused or the recording device is turned off.
The signal may be applied immediately before the droplet ejection signal is applied after recording is stopped in the FF state.

□In other words, when the viscosity of the recording liquid in the liquid flow path may not necessarily be within a suitable range under the environmental conditions such as the temperature when the recording device is used, the droplet ejection signal is By always applying this immediately before is applied to the heater, the viscosity of the recording liquid during droplet ejection can always be adjusted to a suitable value. Alternatively, the viscosity of the recording liquid may be maintained within a suitable range under the environmental conditions such as the temperature during use of the recording device, but after a certain period of recording suspension or stoppage, as mentioned above, If the viscosity of the recording liquid increases due to the evaporation of solvent components into the outside air, count the time during which recording is paused or stopped, and when resuming recording after a certain period of time has elapsed. It is only necessary to apply a heating electric signal to the heater.

It should be noted that after how long the recording has stopped, the electric signal for heating should be applied to the heater when recording is resumed.

Whether or not the viscosity of the recording liquid in the liquid flow path, especially near the orifice, deviates from the preferred range due to a recording pause or stop time of this length depends on the characteristics of the device used, the physical properties of the recording liquid, and the performance of the device. Since it varies depending on the environmental conditions such as temperature and humidity of the place where it is installed and used, it may be selected appropriately depending on the individual device and its usage condition.

In the recording apparatus of the present invention, after the electric signal for heating is applied to the heater, the electric signal for ejecting droplets not used for recording is applied to the heater, and then the electric signal for ejecting droplets not used for recording is applied to the heater. A signal may also be applied to the heater.

In the apparatus of the present invention, the electric signal for ejecting droplets not used for recording refers to the electric signal for ejecting droplets that is applied to the heater to eject droplets, and the droplets are collected in the apparatus. This is a signal that is applied to prevent the recording material from being used for recording on the recording material.

In this way, if an electric signal for ejecting droplets not used for recording is applied to the heater after the electric signal for heating is applied to the heater, the recording pause or stop period will become very long.
Even if the viscosity of the recording liquid increases significantly due to evaporation of solvent components, the heater first generates heat using an electric signal for heating.
The high viscosity part of the recording liquid is heated and its temperature rises.
The viscosity of the recording liquid is lowered to such an extent that good droplets cannot be formed, but droplets can be ejected, and in this state, an electrical signal for ejecting droplets is then applied to the heater. As a result, the recording liquid in this area is ejected out of the liquid flow path, and the recording liquid whose viscosity is within the range suitable for ejection is supplied to the vicinity of the heater. A discharge state is obtained.

Therefore, if the electric signal for ejecting droplets not used for recording is simply applied to the heater, recording liquid whose viscosity is not within the range suitable for ejecting droplets during recording will be ejected. , is applied under conditions that allow it to be removed from the liquid flow path.

An example of a flowchart of a mechanism for controlling recording in the apparatus of the present invention is shown in FIGS. 4 and 5. In the figure, t is the upper limit of preheating, that is, the recording medium 11 hour within the range where the heating electric signal is applied and the recording liquid is heated within the range where the recording liquid is not ejected; T indicates the upper limit of the pause time that requires preheating, and if T is exceeded, preheating and preliminary discharge are required.
indicates a time. Further, preliminary ejection refers to ejecting droplets that are not used for the above-mentioned recording.

In the control mechanism shown in Fig. 4, after the power is turned on,
When a print signal, that is, an electrical signal for ejecting droplets used for recording, is applied, before the recording liquid for recording is ejected, preheating and preliminary ejection are performed in this order, and then ejection is performed. An electric signal for ejection is generated from the signal generating means and applied to the heater, and the recording liquid is ejected to perform printing. Further, when the recording pause time exceeds t, preheating is performed, and when the recording body 1 hour further exceeds T, preheating and preliminary ejection are performed.

In the control mechanism shown in FIG. 5, when the power is turned on, preheating and preliminary ejection are performed, and if no printing is performed after the power is turned on, a recording pause time is counted. If the recording pause time exceeds t, preheating is performed, and if the recording pause time further exceeds T, preheating and preliminary ejection are performed. The control after the recording is stopped after printing is performed is the same as that in FIG. 4.

The device of the present invention described so far is of the type that uses thermal energy to form droplets, and uses an energy generating element (heretofore referred to as a heater) for ejection.
In the past, the recording liquid was heated to the extent that the recording liquid was not ejected, but these devices may be provided independently. In this case, a recording liquid heating means such as a heater may be separately arranged to provide the liquid jet recording apparatus of the present invention that performs the control as described above.

In the liquid jet recording apparatus of the present invention described above, when performing recording, that is, immediately before applying the electric signal for droplet ejection to the heater 13, the signal for heating the recording liquid and the electric signal used for recording as necessary are used. The viscosity of the recording liquid to be ejected is mainly adjusted within a suitable range in order to always obtain a good droplet ejection condition during droplet ejection. Even when resuming recording after a particularly long recording stop or stop period, a good and stable droplet ejection condition can always be obtained.

Furthermore, since heating of the recording liquid using the recording liquid heating signal is not performed frequently and the heating time is extremely short, the durability of the parts surrounding the heater of the recording apparatus is not reduced due to the influence of heat. Furthermore, a good and stable droplet ejection condition can always be obtained without causing any deterioration of the recording liquid that remains near the heater when recording is stopped due to the influence of heat.

In addition, in the apparatus of the present invention to which a method of using thermal energy is applied for droplet formation, a recording liquid heating means is provided mainly to adjust the viscosity of the recording liquid in order to obtain a good droplet ejection state. The droplet forming means can also be used, and there is no need to provide a means for heating the recording liquid, resulting in a liquid jet recording apparatus that can always provide a good and stable droplet ejection condition.

Example 1 24 orifices (orifice diameter 50x40u)
Using a liquid jet recording apparatus of the present invention having recording heads as shown in FIG. 1 arranged vertically in a row at intervals of 0.141 am, a recording liquid having the following composition was used.
This device was filled with 1
When resuming recording after a time recording pause period, the voltage 2
3.5V, pulse width 52s, frequency 10K) 12 heating electric signals at voltage 23.5V, pulse width 10JLs
, an electric signal for droplet ejection with a frequency of 2 KHz is applied immediately before being applied to the heater to perform recording, and there is no difference in the recording signal until the droplets of the recording liquid used for recording are ejected from all 24 orifices. By measuring the number of ejected droplets, the recording apparatus was evaluated regarding ejection failure after recording was stopped. The results are shown in Table 1.

The composition of the recording liquid used for recording was as follows.

[Recording liquid composition]

G.1. Direct Black 1111 2 parts by weight Diethylene glycol 30 parts by weight Water 70 parts by weight Comparative Example 1 It has the same configuration as Example 1, and during recording, only the electric signal for ejecting the recording droplets used for recording is applied to the heater. A recording device was used, filled with the recording liquid used in Example 1, and when resuming recording after a 1-hour recording stop period in an environment of 25° C. and 30× RH, the voltage was
23.5V, pulse width 10g5. Recording was carried out by applying only an electrical signal for ejecting droplets at a frequency of 2 KHz to the heater, and in the same manner as in Example 1, the ejection failure of this apparatus after recording was stopped was evaluated. The results are shown in Table 1.

Example 2 Using the apparatus used in Example 1, the recording pause time was set to 12 hours, and after applying a heating electric signal, a 100-pulse droplet ejection electric signal was applied to the heater to remove the liquid not used for recording. The recording liquid used in Example 1 was applied to the apparatus of the present invention, which performs recording in the same manner as in Example 1, except for ejecting droplets and then applying an electrical signal for ejecting droplets for recording to the heater. Filling was performed, recording was performed, and the ejection failure of this apparatus after recording was stopped was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 Recording was carried out in the same manner as in Comparative Example 1, except that the recording pause time was changed to 12 hours, and the ejection failure of this apparatus after the recording pause was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Table 1

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of the recording head section of the liquid jet recording apparatus of the present invention, FIG. 2 is a partially enlarged view of the area around the nozzles of the recording head section shown in FIG. 1, and FIG. 3 is an electrothermal 4 and 5 are flowcharts of a mechanism for controlling recording in the apparatus of the present invention. l: Supply tube 2: Sub tank 3: Suction tube 4: Supply pipe unit 5: Liquid chamber 6:
Supply pipe unit holder 7: Nozzle part 8: FPC 9: Base plate 1O: Bushing 1]: Front plate 12 Niorifice 13: Heater 14: Liquid flow path t: Upper limit of recording pause time that does not require preheating T: Preheating Upper limit of required recording pause time Figure 1 Figure 2 □ Haruma (now) Figure 3 Figure 4

Claims (4)

[Claims] (1) In a liquid jet recording device having an electrothermal energy converter used to apply an electric signal to heat a liquid and form flying droplets, droplets are ejected to the electrothermal energy converter. Liquid ejection characterized by comprising: ejection signal generating means for causing ejection, and heating signal generating means for generating an electric signal applied to the electrothermal energy converter within a range in which droplets are not ejected. Recording device. (2) The liquid jet recording apparatus according to claim 1, wherein the electric signal generated by the heating signal generating means is a high frequency signal. (3) The liquid jet recording apparatus according to claim 1, wherein the ejection signal generating means and the heating signal generating means are the same. (4) The liquid jet recording apparatus according to claim 1, wherein the ejection signal generating means and the heating signal generating means are different.