JPS61146553A - Liquid jet recording device - Google Patents

Abstract

PURPOSE:To swiftly and easily render printing conditions most suitable by providing a heat control means which, corresponding to an environmental condition, furnishes a recording unit control means with an electric signal of a pulse width within a range in which a flying droplet should not be formed, and performs heating of liquid. CONSTITUTION:The title device is provided with the following components: (a) a liquid jet recording unit 100 which has a discharge energy generating means 102 which includes an electrothermal energy conversion element which can heat liquid and form a flying droplet, corresponding to an electric signal supplied, and discharges the formed flying droplet and performs recording on a material P to be recorded; (b) a recording unit control means 110 which can establish a pulse width of an electric signal, and corresponding to input of a recording signal SA, furnishes a discharge energy generat ing means 102 with an electric signal to form a flying droplet; (c) a heating control means 140 which has a pulse width setting means 142 which establishes a pulse width for the recording unit control means 110; and corresponding to an environmental condition, by furnishing the recording unit control means 110 with an electric signal of a pulse width within a range in which a flying droplet should not be formed, heating of liquid is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a liquid jet recording device that performs recording by ejecting liquid to form ejected droplets and attaching the droplets to a recording material such as paper, and particularly relates to The present invention relates to a liquid jet recording device that applies ejection energy to liquid to form ejected droplets.

[Prior Art] A liquid jet recording method (inkjet recording method) is a recording method in which ejected droplets of a recording liquid are formed using various methods, and the droplets are attached to a recording material such as paper to perform recording.

Among recording devices (printers) that apply such recording methods, a type of liquid that uses heat as energy to form ejected droplets is a device that has a structure suitable for high-density multi-orifice recording heads. Examples include jet recording devices (hereinafter referred to as inkjet printers).

Inkjet printers that use heat as droplet ejection energy usually heat the recording liquid to give it a displacement that causes a rapid volume increase, and then eject it from an orifice (droplet ejection hole) in the nozzle. It has a droplet forming means for forming droplets of recording liquid, and an electrothermal energy conversion element (hereinafter referred to as a discharge heater) that can generate heat and heat the recording liquid by applying an electric signal. ° Equipped with a recording head.

On the other hand, the recording liquid used when recording with an inkjet printer has different recording properties.

Water-based recording liquids are mainly used for safety reasons.

This aqueous recording liquid is generally formed of a recording agent 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.

In the above-mentioned printers that use heat as droplet ejection energy and other printers that apply droplet formation methods, the orifice provided at the tip of the nozzle from which recording liquid is ejected is constantly It is often open to the outside air outside the device.

Therefore, if recording is not performed for a long period of time, water and volatile organic substances, such as water and 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.

Additionally, some printers cap the ejection surface with an orifice when the device is not in use, such as when the power is off, but even with this type of capping, the orifice is not completely isolated from the outside air. Since there is no,
The above problem also occurs in such printers.

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, it is necessary to maintain the temperature of the recording liquid within a predetermined range when the droplet ejection signal is not applied. Also, a recording method is known from JP-A-58-187384 in which the recording liquid is heated by constantly applying an electric signal to an ejection heater at a level at which no recording droplets are ejected.

However, even in printers using this type of system, an electrical signal is applied to the ejection heater so that the recording liquid is always kept at a high temperature even during a relatively long recording pause or stop period. There have been cases where a problem arises in that the solvent component in the liquid evaporates more easily, making the droplet ejection failure more likely to occur when recording is resumed as described above. In addition, in this method, the area around the ejection heater is constantly heated, which may impair the durability of the parts surrounding the ejection heater, or cause accumulation of heat around the ejection heater during the recording pause period. The physical properties of the recording liquid itself may change due to heat, which may cause 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. Ta.

Therefore, it is conceivable to configure an inkjet printer in which preliminary heating is performed in advance after the power is turned on and before or at the start of printing to keep the ink warm and optimize ejection. This preliminary heating can be done by driving a heating means to apply heat to the ink from the outside, or by supplying print output to the ejection energy generating element to the extent that the ink is not ejected, to heat the ink from the inside. It is conceivable to perform a process of adding .

However, conventionally, print output was performed from a microprocessing unit (MPU) that controlled each part of the printer via a boat IC, so this preliminary heating,
In particular, when heating from the inside, it is extremely difficult to add an appropriate print output in consideration of environmental conditions and the like because the processing speed of the MPU is slow.

[Objective] The present invention eliminates such conventional problems, provides a dedicated controller for controlling the ejection of the head unit, and uses the controller to perform appropriate backup in consideration of environmental conditions when starting up the printer or starting printing. An object of the present invention is to provide an inkjet printer that can quickly and easily optimize printing conditions by performing heat treatment.

[Structure of the Invention] In order to achieve the above object, the present invention provides an electrothermal energy conversion element capable of heating a liquid and forming flying droplets in response to the supply of an electric signal, as shown in FIG. A liquid jet recording unit (100) having a discharge energy generating means 1G2 including a discharge energy generating means 1G2 and recording on a recording material P by discharging the formed flying droplets. , a recording unit control means 110 that supplies an electric signal to the ejection energy generation means 102 to form flying droplets in response to the input of the recording signal SA; and a recording unit control means 1.
Pulse width setting means 1 for setting the pulse width for 10
42, depending on the environmental conditions, the recording unit control means 1
10, and heating control means 140 for heating the liquid by setting an electric signal with a pulse width within a range in which flying droplets are not formed.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 shows an example of the configuration of the recording section of an inkjet printer to which the present invention can be applied. This example shows the present invention applied to an inkjet printer in which a head unit is mounted on a carriage that moves in a predetermined direction with respect to the recording surface. It was applied. In addition, FIGS. 3(A) and (B) are, respectively,
3 is an enlarged view of the head unit in FIG. 2, and a further enlarged view of its nozzle portion. FIG.

In these figures, HU is a liquid ejecting unit mounted on a carriage C, and the number of units can be provided depending on the ink color used. FC is the liquid jet recording unit)
This is a flexible cable that collects signal lines, etc. that control ink ejection by the HU.

The carriage C is fixed to a belt or the like, for example, and is moved in the S direction in the figure by a driving means such as a motor.

R is a guide rail that guides the movement of the carriage C in the S direction.

In addition, P is a recording material such as paper that is conveyed in the f direction in the figure, and P
L is a platen that forms the recording surface of the recording paper P. That is, the carriage C can move in the S direction in the figure along the guide rail H by the driving means and perform recording on the recording surface.

ST is a sub-tank provided in the carriage C, TBI and Ta2 are ink supply pipes that communicate the main tank (not shown) and the sub-tank ST, and the sub-tank S, respectively.
This is an ink supply pipe unit that communicates between T and the liquid chamber IR in the head unit HU.

CAP is a cap member, and the liquid jet recording unit H is located at the home position H of the carriage C in the S direction.
When the carriage C is at the home position, the cap member CAP is moved toward the liquid jet recording unit HU by a driving means such as a motor and comes into contact with the ejection surface of the liquid jet recording unit HU. can. SP is a collection member that comes into contact with the ejection surface of the liquid jet recording unit (HU) to collect ink, and is made of, for example, a water-absorbing porous material.

In FIG. 3(A), BP is the supply pipe unit TB2
, a liquid chamber IR, a nozzle part NZ, a flexible cable FC, etc. are arranged, a base plate for supporting these, BSH is an elastic member for supporting the periphery of the nozzle part, and FP is a front plate. TSt is a temperature sensor such as a thermistor for detecting temperature, HTR is a heater consisting of an electrical sudden change specimen such as a positive temperature coefficient thermistor provided in the head unit HU to externally heat and keep the ink warm, and TP is a heat conductive plate.

Further, in FIG. 3(B), OR is an orifice as an ink discharge hole, and in this example, a predetermined number of orifices OR are arranged in the nozzle part NZ in the vertical direction. ICH is a liquid flow path that communicates the orifice OR with the liquid chamber IR, and ET is an ejection heater serving as an ejection energy generating element that provides thermal energy for ejection to the ink in the liquid flow path ICH.

This device! To perform recording using the ink, first, ink is supplied from the main tank to the sub tank ST via the supply pipe TBI, and then to the liquid chamber I via the supply pipe Ta2.
Next, a flexible cable F is connected from a signal generating means for droplet ejection, which will be described later, to fill recording liquid into R and liquid flow path ICH.
An electric signal is applied via C to energize the discharge heater ET. As a result, the ejection heater ET generates heat, and thermal energy is applied to the recording liquid in the liquid flow path ICH near the ejection heater ET. Bubbles are generated within the liquid, and the recording liquid located downstream of the ejection heater ET is ejected from the orifice OR, forming droplets of the recording liquid. Recording is performed by making droplets of the recording liquid adhere to a recording material P such as paper that has been sent in front of the nozzle section.

FIG. 4 shows an example of the configuration of a control device for an inkjet printer of the present invention. This control device receives print data from a host computer, stores print data for one line, and controls a head unit (IU). The print head is controlled to perform printing.

First, l is a programmable peripheral interface (hereinafter referred to as PPI), which functions to receive print data sent from the host computer of the printer according to this example in parallel, and send the print data to the MPU2. ,
2 is a microprocessing unit (hereinafter referred to as MPU) that controls the console 6 and performs input processing for the home position sensor 7; 3 is a microprocessing unit (hereinafter referred to as MPU) that controls each part in the printer and performs the processing procedure described below; RAM as a line buffer memory that stores one line of print data
, 4 is a ROM for the font of printout characters, 5 is an MPU
This is a control ROM that stores the processing procedures (FIGS. 5 to 7) executed by the computer 2. Each of these parts 1 to 5 is connected to the address bus A.
B and are connected via a data bus DB.

Reference numeral 6 represents a console having a keyboard switch, a display lamp, etc., and 7 represents a home position sensor provided near the home position of the carriage C. 8 is a cap mode switch for detecting the state of the cap member CAP, that is, opening/closing of the cap with respect to the head HU; 9 is a paper sensor for detecting the absence of printing paper.

Reference numeral 10 denotes a controller for the head unit, which latches print data and print output time, and starts print output in response to a command from the MPU 2. That is, in this example, the controller 10 is used as a dedicated IC circuit to speed up the processing. As this controller 1G, for example, the one disclosed by the applicant in Japanese Patent Application No. 182802/1982 can be used. In addition,
The print data once latched is output as is if there is no need to change it.

11 is a driver for driving the head unit HU according to the controller 10, and 13 is a protection circuit for the head unit HU. Reference numeral 14 denotes a driver for driving the ink heating and heat retention heater HTR installed in the head unit HU. 15 is a temperature comparison element of the ink temperature detection element TS provided in the head unit (2). 16 is a switch for instructing switching of printing fonts. 17 is a temperature comparison circuit 15. This is a signal input switching device for the switch 16 and is controlled by the MPU 2.

A driver 18 drives a motor N3 for moving the cap member CAP relative to the head unit HU. Reference numerals 22 and 24 are drivers for driving the paper feeding motor M2 and the carriage moving motor M2, respectively. Further, 20 and 21 are a solenoid for a valve used for venting air in the head unit HU, and its driver, respectively.

Here, an overview of the processing in the inkjet printer shown in FIGS. 2 to 4 according to this example will be described. In this example,
When turning on the power of the printer and starting printing, the head unit (2) undergoes preliminary heating processing and preliminary ejection processing to improve the ink ejection state. Furthermore, in connection with these processes, capping of the head unit (HU) is appropriately controlled. During the preliminary heat treatment, external heat treatment and/or internal heat treatment shall be performed.

Here, external heating refers to heating the ink in the head unit (HU) from the outside by driving the heater HTR, and internal heating refers to ejecting print output pulses within a range in which ink is not ejected from the head unit (HU). During internal heating, which refers to heating from inside the head by supplying energy to the energy generating element, a print output start signal is sent to the head unit/controller 10 at each set frequency.

When performing preheating, especially internal heating.

Although it is preferable to apply a print output with an appropriate pulse width, frequency, and voltage to the head unit (HU), by using the head controller 10, sufficient processing is possible even at the normal processing speed of the NPt1.

That is, according to this example, the parameters of each print output can be freely changed and set as necessary, so that optimal head heating and software simplification and speeding up can be achieved.

Also, when performing preliminary ejection, it is preferable to apply an appropriate print output to the head unit (HlJ) using the pulse width, frequency, and voltage as parameters. In this example,
These parameters and the number of ejections are changed depending on the environmental conditions.

According to this example, such a case can be easily handled by software, and optimal preliminary ejection becomes possible. Furthermore, in this example, the head controller 10 is used to set the print output during preliminary ejection to 1'' for all dots.Therefore, in this case, there is no need to change the print data each time, so the software Simplification,
Processing speed can be increased.

The print state optimization process in this example will be described below.

5(A) and CB) show an example of the printing condition optimization processing procedure according to the present invention. 'Immediately after the printer is powered on, as an initial process, the hardware
and initialize the head unit controller 10, and in the software, the line buffer memory R
The AM3 is initialized, the control RON5 is checked for operation, and each parameter used in the process is initialized (step S1).

After this initial processing is completed, the head cap motor M3 is activated while monitoring the cap mode switch 8 by the MPU2.
to open the head cap (Stella 7).
P S2) , and while monitoring the home position sensor 7, operate the carriage motor M2 to move the carriage C and position it at the home position H (
Then, while monitoring the cap mode switch 8, the cap motor M3 is operated to perform head cap closing processing for the head unit HU (step S4), and the motor M1 is roughly driven, for example, for one line. After these processes, the head unif)
Performs initial processing to seal the HU.

In the initial processing, first, preliminary heating processing (step SH) of the head unit HU is started.

FIG. 6 shows an example of a preliminary heating process procedure for performing external heating and internal heating. As mentioned above, internal heating is performed by controlling the controller IO to output pulse widths, voltages, and high frequencies within a range that does not eject ink. Head unit) In addition to HU,
External heating refers to generating heat inside the head unit HU, and external heating refers to heating the head unit HU by turning on the driver 14 from the MPU 2 using the heater HTR provided in the head unit HU as a heating element. In step S old, external heating is started, and in step SH2, the head unit controller IO is set to external heating mode.Next, in step SH3, the print output is set to 1'' for all dots, and in step SH4, the print output is set to 1'' for all dots. Start internal heating.During this internal heating, the pulse width and voltage of the print output are adjusted as described below.

Make sure to set the frequency appropriately.

Once you start preheating the head like this.

Head unit) Measure the temperature of the HU, and if the temperature of the HU is higher than a certain temperature on the high temperature side (step 5H5), the preheating is finished. If preheating is started and the high temperature does not exceed a certain temperature even after a certain period of time has passed (step 5), an internal heating stop command is sent to the controller 10 in step SH7 to prevent thermal damage to the head. Then, in step SH8, the driver 14 is turned off and external heating is stopped. That is, at this time, preheating is stopped and the process returns to step SS in FIG. 5(A). It should be noted that the constant temperature on the high temperature side refers to the upper limit operating temperature of the head unit 12 (for example, 42° C.), and it goes without saying that the external heating and internal heating may be started and stopped in any order.

Referring again to FIG. 5, after stopping the preheating, for a predetermined period of time,
After waiting, the temperature distribution in the locally heated head unit (HU) is averaged (step S8), and after this waiting, preliminary ejection processing (step SJ) is performed. When heat treatment is performed, the waiting time may be set to a relatively long time, and in this case, it can be set to, for example, 500 S.

FIG. 7 shows an example of the preliminary ejection processing procedure. Here, first, in step SJI, the head unit controller 1
The ejection conditions are set to 0, and then, in step SJ2, the print output for all dots is set to 1".Then, in step SJ3, the print output is set to 1".
In addition to this, ejection is performed, and this is repeated a prescribed number of times through the process of step SJ4, and after the completion of the process, the process returns to step SIG in FIG. 5 and shifts to a print standby state. That is, the initial processing for the head unit (HU) is completed, and the procedure shifts to a print standby state from the host computer. Note that the parameters of the prescribed number of ejections and the ejection conditions can be appropriately set depending on the environmental conditions as described later.

When a print signal is supplied from the host computer in the print signal standby state (step 510), the print data is P
RAM3 latched to PII and used as a line buffer
will be forwarded to. Therefore, a signal from the temperature detection element TS provided in the head unit HU is detected by the temperature comparison circuit 15, and it is determined whether the low temperature side temperature is higher than a certain temperature (1, for example, 20°C or higher) (step 5it). If the determination is affirmative, the head cap motor M3 is driven to perform cap opening processing (step 512), and then the controller 10 is set to the normal printing mode to perform preliminary ejection (see FIG. 7 in step S). If it is determined that the temperature is lower than the certain temperature on the low temperature side, the cap is opened (step 513), and then the preheating treatment (step SH: see Figure 6) is performed.
After waiting for a predetermined time (step 515), the controller 1G is further set with discharge conditions and the number of discharges, and preliminary discharge is performed (step SJ, see FIG. 7).

Note that the standby time in this case can be made shorter than the above-mentioned standby time when rapid heating is not performed such as during startup. Note that the temperature on the low temperature side is constant (Step 51B)
, moves to printing state. Carriage motor M
The heat treatment is not performed during the printing operation when the printer 2 is being driven.

Further, heat treatment can also be performed without increasing power consumption in connection with the printing process in step S20. That is, when the carriage C is in operation and the direction of movement of the carriage is changed at both ends of the movement range, the carriage C stops there, so the heat treatment may be performed at that time.

When printing is started and, for example, the - character is printed and the carriage motor M2 is stopped (step 520),
It is determined whether the temperature of the head unit (2) is higher than a certain temperature on the low temperature side (step 521).

If the judgment is positive here, the process moves to the next step, and if the judgment is negative, the driver 14 is turned on and external heating is started (
The process proceeds to step 522). That is, it is determined whether the temperature of the head unit HU is equal to or higher than a certain temperature on the high temperature side (step 523).

Here, if the judgment is positive, immediately, if the judgment is negative, after waiting for a predetermined time (for example, 200 m5) (step 5).
24), stop external heating (step 525).

Next, as shown in FIG. 5(B), the paper feed motor 2 is driven to feed the paper (step 530), and step S2
The process proceeds to the next stage through steps S31 and S32, which are similar to steps S1 and S22, respectively. That is, the NPU 2 turns on the internal timer and determines whether or not the print data is latched to the PPII within a predetermined time (for example, within 5 seconds) (steps 940, 541). If the determination is affirmative here, the result is as shown in FIG. The process moves to step 31B of A). On the other hand, if the determination is negative, the driver 14 is turned off to stop external heating (step 542), the carriage motor M2 is driven to position the carriage C at the home position lLH (step 543), and the cap motor M3 is then driven to close the cap. After processing (step 544), FIG.
) returns to step SIO.

In this example, after the preliminary heating process, the preliminary ejection process of ejecting droplets that are not used for recording is performed, so the recording pause or stop period is extremely long, and the evaporation of the solvent component is caused. Even if the viscosity of the recording liquid increases significantly due to the above, it is possible to optimize ejection during printing. That is, first, the high viscosity portion of the recording liquid is heated by the preheating process, and its temperature is increased, and the viscosity of the recording liquid is lowered to the extent that droplets can be ejected.

By performing the preliminary ejection process in this state, the recording liquid in this area is ejected out of the liquid flow path ICH.
Recording liquid whose viscosity is within a suitable range for ejection is supplied near the ejection heater ET, and a good recording liquid ejection condition can be obtained from then on. In order to confirm the stability of this discharge state, the applicant conducted the following experiment.

[Experiment using Example] 24 orifices (orifice diameter 50 x 40 IL)
Using an inkjet printer according to this example, which has a recording head section as shown in FIG. Fill the device and store at 25℃30%RH
When resuming recording after a 12-hour recording suspension period under
A KHz signal was applied to the ejection heater ET during preheating, then a voltage of 23.5 V, a pulse width of 10 JLS, and a frequency of 2 KHz was applied for 100 pulses to the ejection heater E to eject droplets that were not used for recording. The recording device was evaluated regarding ejection failure after recording was stopped by measuring the number of non-ejected droplets in response to the recording signal until the recording liquid droplets used for recording were ejected from all 24 orifices. . The results are shown in Table 1.

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

C, 1, Direct Black 13 2 parts by weight diethylene glycol 30fl amount! water
70 parts by weight [Experiment using comparative example] A recording device having the same configuration as the example and in which only an electric signal for ejecting recording droplets used for recording is applied to the ejection heater was used for recording. This was filled with the above-mentioned recording liquid, and when recording was resumed after a 12-hour recording suspension period at 25° C. and 30% RH, the voltage was 23.5 V.
Recording was performed by applying only an electric signal for ejecting droplets with a pulse width of 10 g5 and a frequency of 2 KH2 to the heater, and the apparatus was evaluated for ejection failure after recording was stopped in the same manner as the experiment using the example. . The results are shown in Table 1.

Table 1 As described above, even when recording is restarted after a particularly long recording pause or stop period, a good and stable droplet ejection condition can always be obtained.

Next, the settings of parameters such as the pulse width 9 frequency and voltage of the print output in the preheating process and the preliminary ejection process will be described.

How long should the recording pause or stop time be in the liquid flow path 10H?
Whether the viscosity of the recording liquid, especially near the orifice OR, deviates from the preferred range depends on the characteristics of the device used, the physical properties of the recording liquid, and the temperature and humidity of the location where the device is installed and used. Since each device is different depending on the environmental conditions, etc., the parameters of print output during preheating, especially internal heating treatment, are appropriately selected depending on the individual device and its usage condition.

In addition, the signal supplied to the ejection heater ET in the preliminary ejection process is set under such conditions that the recording liquid whose viscosity is not in the range suitable for ejecting droplets during recording can be ejected and removed to the outside of the liquid flow path ICH. so that it is applied.

Furthermore, the number of ejections in the preliminary ejection process is made variable depending on the environmental conditions at that time, so that efficient processing can be performed.

FIG. 8 shows the electric signal applied to the discharge heater ET, where ma0 is the voltage and at is the pulse width. If bubbles are generated due to heating when a signal is supplied to the ejection heater ET during the preheating process, subsequent ejection of droplets may become unstable or non-ejection may occur in some cases. There is also. Therefore, the electric signal applied to the discharge heater ET during preheating must be within a range that does not generate bubbles on the discharge heater ET.

On the other hand, since these preheating treatments are set when the printer is turned on or when printing starts, the frequency of use of preheating is extremely high.Therefore, these preheating treatments degrade the durability of the ejection heater ET. In the preheating treatment using the discharge heater ET, the inventors have determined that the power (W) applied to the discharge heater ET
) was kept constant, and the durability of the discharge heater ET was examined when the pulse width II and the applied voltage MA0 were varied.
The smaller the pulse width wt and the applied voltage ma0, the smaller the heater ET.
It was confirmed that the durability of

Next, the time required to heat the head unit H to a desired value is determined by the power (W) applied to the discharge heater ET.
), but in terms of device performance, it is desirable that the time required to start printing, that is, the waiting time, be short.

However, as mentioned above, it is not desirable to make the voltage applied to the discharge heater ET unnecessarily high in terms of durability of the heater.Furthermore, if bubbles are generated on the discharge heater ET during preheating, It is also difficult to increase the pulse width because it causes printing defects or non-ejection.

Therefore, in order to raise the head temperature to a desired temperature in a short period of time without affecting the durability of the heater ET and without causing foaming on the heater,
It is effective to increase the frequency of the electric signal applied to the discharge heater ET.

FIG. 9 shows one hour (minute) using the frequency of the preheating signal applied to the discharge heater ET as a parameter.

An example of the relationship with the head temperature (O) is shown below, with the applied voltage ma0 being 24v, the pulse width wt being 54g, and the frequencies being 1OKHz, 5KHz, and 2KHz. The temperature is detected by a temperature detection element TS.

From this point of view, the applicant conducted experiments as shown in the following two examples by changing the voltage, pulse width, and frequency.

(Example 1) 24 orifices (orifice diameter 50X 40%m)
Using an inkjet printer according to this example having nozzle parts NZ as shown in FIG. 3(B) in which the nozzles are arranged in a line in the vertical direction at intervals of 0.141 mm, a recording liquid having the same composition as described above was applied. The mixture was filled into the apparatus and preheated under the conditions shown in Table 2 by supplying electricity No. 4A@ to the discharge heater ET.

Then, the surface of the heater was observed using an optical microscope to confirm the presence or absence of bubble generation. The results are shown in the second
Table (Example 2) Using an inkjet printer similar to (Example 1), fill the device with a recording liquid having the above composition, apply a signal to the ejection heater nail under the conditions shown in Table 3, and perform preheating treatment. The durability of the heater ET was investigated by repeating the above steps. The results are shown in Table 3.

Table 3 For the above reasons, it can be seen that the pulse width of the electric signal supplied to the ejection heater ET in the preheating process should be set to be smaller than the pulse width of the electric signal during recording. According to more detailed experiments by the applicant, the pulse width is preferably in the range of 1 to 1/20 of the pulse width during recording.

Further, it can be seen that the electric signal supplied to the ejection heater ET in the preheating process may be set so that the applied voltage is equal to or lower than the applied voltage applied during recording.

Furthermore, if the frequency of the electric signal during preheating is set higher than that during recording, the time required for heating can be shortened.

As described above, these parameters and the number of pulses can be set extremely easily by using the controller 10.

Next, the ejection conditions in the preliminary ejection process will be described.

When recording is suspended or stopped for a long time, the ink that has accumulated in orifice OR and its vicinity increases in viscosity due to evaporation of water, volatile organic solvents, etc., and is in a state where it is difficult to be ejected. The viscosity of the stagnant ink can be lowered by the above-mentioned preheating treatment, but the viscosity is higher than that of ink suitable for recording, and the droplet size is high.

In the two examples, preheating is followed by preliminary ejection because the ink discharge time is different and is not suitable for recording.

During the preliminary ejection process, the ejection heater ET
Since ejection does not necessarily occur from the first pulse of a signal applied to It is possible to shorten the time required and increase efficiency.

Specifically, the energy of the signal during preliminary ejection can be increased by making the voltage and/or pulse width larger than that during recording. In other words, the voltage and pulse width of the signal applied to the ejection heater E during printing can be increased. Pulse width is 24V and 10V respectively
ps, the voltage and/or pulse width of the signal may be made larger than those values during preliminary ejection.According to the applicant's experiments, the voltage should be 1 to 5 times that of printing, preferably 1 to 2 times, and 1 to 5 times the pulse width.
Good results were obtained when the amount was doubled, preferably 1 to 2 times.

Regarding the setting of the ejection time, the number of ejections, that is, the number of pulses, can be set according to the environmental conditions.According to the applicant's experiments, preliminary ejection after turning on the power and before starting printing (as shown in Fig. 5 (A)) In step SJ following step SB, 10
When a 0 to 15G pulse was applied to the ejection heater ET, good printing quality was obtained thereafter. After printing starts, the viscosity of the ink is higher in low-temperature environments, making ejection more stable than in high-temperature environments.

Therefore, it is preferable to appropriately set the number of times of ink ejection.
0°C) or higher (step Sl in FIG. 5(B)
In the case where the affirmative judgment is made in l and the preliminary ejection in step S), when 20 to 50 pulses are applied to the ejection heater E, the ejection is stable and the temperature is lower than the constant temperature on the low temperature side (when the judgment is negative in step S11) In the preliminary ejection, it was confirmed that the ejection was stable when 50 to 100 pulses were applied to the heater ET.

Also regarding the ejection conditions for these preliminary ejections.

It is sufficient to set the controller lO during processing, and MP
Processing can be performed quickly and appropriately without increasing the burden on U2.

Note that the area where the printer according to this example is used is limited,
If it is clear in advance, the number of ejections can be changed depending on the region.For example, in high temperature and low humidity regions, the ink is extremely dry due to constant high temperature. It is also possible to stabilize the amount of preliminary ejection on the low temperature side by increasing the preliminary ejection amount on the low temperature side, and also to change the above-mentioned value for the ejection quantity so as to obtain stable ink ejection.

In the embodiment, an inkjet printer in which a head unit is mounted on a carriage has been described, but the present invention can also be applied to a so-called full multi-type inkjet printer that is equipped with a plurality of head units in the width direction of recording paper. Of course.

In addition, when setting each parameter in the preliminary heating treatment, each parameter in the preliminary discharge treatment, and the number of discharges,
In addition to being adapted to the temperature conditions as in the example,
For example, it can be adapted to environmental conditions such as humidity and pressure.

[Effects] As explained above, according to the present invention, an appropriate pulse width is set for the head controller to perform preheating treatment after the power is turned on and before or at the start of printing. This has the effect of realizing a liquid jet recording device in which generation of bubbles on the heater can be prevented, printing conditions can be quickly and easily optimized, and the ejection energy generating means does not deteriorate.

Further, according to the present invention, there is an effect that the setting conditions for preheating can be easily changed.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the present invention, FIG. 2 is a perspective view showing an example of the configuration of an inkjet printer according to the present invention, and FIGS. FIG. 4 is a flowchart of an inkjet printer according to the present invention. FIG. 6 and 7 are flowcharts showing an example of a preliminary heating treatment procedure and an example of a preliminary discharge treatment procedure in the process shown in FIG. 5, respectively, and FIG.
) is a waveform diagram for explaining a print output signal supplied to the circuit. FIG. 9 is a characteristic curve diagram showing the relationship between supply time and temperature using the frequency of the print output signal supplied to the head unit as a parameter. H■...liquid jet recording unit (head unit), C...carriage, R...guide rail, TBI, Ta2...supply pipe. FC...flexible cable, ST...subtank, CAP...cap member, P...recording material, PL...platen, S...carriage running direction. f...recording material conveyance direction, H...home position, NZ...nozzle section, FP...front plate, IR...liquid chamber, IC) I...ink flow path. OR...orifice, TS...temperature detection element, )ITR...heater for external heating, ET...heater for discharge, Ml, M2. M3...Motor, l...Programmable peripheral interface (PPI), 2...Micro processing unit (MPU), 3...Line buffer RAM. 4... Font generation ROM, 5... Control ROM, 6... Console, 7... Home position sensor, 8... Cap mode switch, 9... Paper sensor, lO... Head unit controller, 11.14,
18, 21, 22. 24... Driver, 13... Protection circuit, 15... Temperature comparison element, 1B... Font selection switch, 17... Input selector. Figure 3 (A) Figure 6 Figure 9 1 hour (minute)

Claims (1)

[Scope of Claims] 1) A discharge energy generating means including an electrothermal energy conversion element capable of heating the liquid and forming flying droplets in response to the supply of an electric signal, and the formed flying liquid A liquid jet recording unit that records on a recording material by discharging droplets, and a pulse width of the electric signal that can be set, and forming the flying droplets on the discharge energy generating means in response to input of the recording signal. recording unit control means for supplying the electric signal to cause the flying droplets to form; and pulse width setting means for setting a pulse width for the recording unit control means, the recording unit control means controlling the formation of the flying droplets according to environmental conditions. 1. A liquid jet recording apparatus comprising: heating control means for heating the liquid by setting an electric signal with a pulse width within a range in which the liquid is not heated. 2) In the liquid jet recording device according to claim 1, the environmental condition is the temperature of the liquid, and the pulse width setting means detects the temperature and sets the pulse width. A liquid jet recording device.