JPH0444856A - Ink jet recording apparatus - 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 [Field of Industrial Application] The present invention relates to an inkjet recording apparatus that performs recording by ejecting ink from a recording head onto a recording material.

[Conventional technology]

2. Description of the Related Art Recording devices such as printers, copiers, and facsimile machines are configured to record images consisting of dot patterns on sheet-like recording materials such as paper and thin plastic plates based on image signals.

The recording device may be an inkjet type,
It can be divided into wire dot type, thermal type, laser beam type, etc. Among them, inkjet type (inkjet recording apparatus) is configured to perform recording by ejecting ink onto a recording material.

Inkjet recording apparatuses have advantages such as low noise because they are non-impact type, and the ability to easily record color images using multicolored inks.

One type of inkjet recording device is an inkjet that uses thermal energy, which uses a recording head that has an electrothermal converter for generating ejection energy, and applies an electric signal to the electrothermal converter to heat the ink and eject it. There is a recording device.

An inkjet recording device using such an electrothermal converter is particularly excellent in that high-speed, high-definition recording is possible.

On the other hand, in this type of inkjet recording device, the heat generated as ejection energy when a driving voltage pulse is applied to the electrothermal transducer is accumulated in the recording head, and the temperature of the recording head increases. The viscosity of the ink filled in the printer may decrease, the amount of ink ejected may increase, and the image quality may change.

Therefore, a method has been proposed in which a fan and a heater are used in combination to maintain the recording head at a predetermined temperature.

[Technical problem to be solved by the invention] However,
The above-mentioned conventional technology has a technical problem in that even if a heater provided in the print head is used, a long waiting time is required after the power is turned on until the temperature of the print head reaches a predetermined temperature at which printing is possible.

As a countermeasure, a method has been proposed in which, in the above-mentioned case, a pulse voltage that does not eject ink is applied to the electrothermal transducer of the print head at the same frequency as the print frequency, thereby reducing the waiting time. .

However, even with this method, it is difficult to sufficiently shorten the waiting time, for example, when the thermal capacity of the print head increases due to full multi-printing.

In particular, in the full multi-head described above, a heat vibrator is used to equalize the temperature in the arrangement direction of the electrothermal transducers of the recording head, which further increases the thermal capacity of the entire recording head and increases the waiting time ( There was an issue of becoming.

The present invention has been made in view of such technical problems, and an object of the present invention is to provide an inkjet printing apparatus that can significantly shorten the waiting time after the printing apparatus is powered on.

[Means for solving RB]

The present invention provides an inkjet recording apparatus that performs recording by ejecting ink onto a recording material using a recording head having an electrothermal transducer for generating ejection energy. To provide an inkjet recording device that can significantly shorten the waiting time after turning on the power of the recording device by having a head heating means that heats the recording head to a predetermined temperature or higher by applying an electric signal. It is something.

In the above configuration, it is preferable that a recording head temperature detection means is provided and the electrical signal is applied when the detected temperature of the recording head is below the predetermined temperature.

〔Example〕

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

FIG. 8 is a schematic perspective view showing the main structure of an inkjet recording apparatus suitable for applying the present invention.

FIG. 8 shows a case of a line-type inkjet printing apparatus equipped with a plurality of full multi-type printheads (four in the illustrated example) capable of full-color printing.

In FIG. 8, reference numerals 11 and 12 indicate two pairs of rollers for sandwiching the recording material 3 such as paper or plastic paper, and transporting it in the sub-scanning direction (conveyance direction) indicated by arrow F.

108k, IOY, IOM, and IOC are fully multi-type inkjet recording heads in which ejection ports are arranged over substantially the entire width of the recording material 13, and are as follows.
These recording heads l0Bk, IOY, IOM, IOC
Any one (or all) of the "recording head 10"
”.

In the case of full-color recording, black, yellow, magenta, and cyan are used as the ink colors ejected from the four recording heads 10, and in the illustrated example, four ink colors are used.
The inkjet recording heads 10 are arranged in this order from the upstream side (from the bottom) in the recording material conveyance direction.

Each of the inkjet recording heads 10 described above is a recording head that discharges ink using thermal energy, and is equipped with an electrothermal converter for generating thermal energy.

Further, the inkjet recording head 10 performs recording by ejecting ink from an ejection port by the growth of bubbles due to film boiling caused by thermal energy applied by the electrothermal converter.

A recovery system 16 faces each of the recording heads 10 instead of the recording material 13 during ejection recovery processing.

Further, each of the inkjet recording heads 10 is mounted on a head mounting portion 17 with their mutual positional relationship regulated.

As described above, an inkjet recording apparatus suitable for applying the present invention, that is, a head mounting section 17 for mounting the recording head 1O, and a recording position of the recording head 10 mounted on the head mounting section 17, are provided. An inkjet recording apparatus is configured, which includes conveyance means 11.12 for conveying the recording material 13.

FIG. 9 is a partially cutaway perspective view showing the main part configuration of the inkjet recording head 10 in FIG. 8. FIG.

In FIG. 9, the recording head IO includes a substrate 22, an electrothermal transducer 23, an electrode 24, a liquid path wall 25, a top plate 26, and the like.

The electrothermal converter 23 and the electrode 24 are formed, for example, by a method of forming a film on the substrate 22 through a semiconductor manufacturing process such as etching, vapor deposition, or sputtering.

Ink 2 is supplied from an ink tank (not shown) to an ink supply pipe 2.
7 and is supplied into the common liquid chamber 28 of the recording head IO.

Reference numeral 29 in FIG. 9 indicates a supply port to which the ink supply pipe 27 is connected.

The ink 2 supplied into the common liquid chamber 28 is supplied into each liquid path 30 by capillary force, and is maintained in a stable state by forming a meniscus at the ejection opening 21 at the tip thereof.

By applying a driving pulse signal to the electrothermal transducer 23, the ink adjacent to the surface of the electrothermal transducer is rapidly heated to cause film boiling (bubbling phenomenon), and the energy of the bubbling causes the ejection port 21 to Ink droplets are ejected from.

Note that 31 is a discharge port surface (where the discharge port 21 is formed).
face) is shown.

With the above configuration, the ejection port density is 400 dpi (1
A multi-type inkjet recording head of 128 dots or 256 dots can be constructed with a high-density arrangement of ejection ports (6 pieces/m).

FIG. 1 is a plan view illustrating a recording head 10 of an inkjet recording apparatus embodying the present invention.

In FIG. 1, ■ is the main body of the inkjet recording head 10, 2 is a heat vibrator for equalizing the temperature in the arrangement direction of the electrothermal transducers 23, and 3 is a heating device for heating the recording head 10. 4 is a heat radiation fin for increasing the heat radiation efficiency of the recording head 1-10; 5 is a fan for generating cooling air to cool the recording head 10; 6 is a fan for generating cooling air for cooling the recording head 10; 10(
This is a temperature detection means for detecting the temperature of the head body 1).

When heat is to be radiated from the recording head IO, cooling air from the fan 5 is applied to the heat radiating fins 4 to perform forced cooling.

Therefore, the temperature of the recording head 10 is determined by the temperature detection means 6.
By controlling the heater 3 and the fan 5 in response to a detection signal from the sensor, the temperature is always maintained within a temperature range T a "" T m in which a predetermined image can be recorded.

For example, if the recording head 10 is a film boiling type full multi-head having 400 dpi and 4737 ejection ports 21, the temperature range T A = T m is 40°C to 50°.
It is set to C.

Therefore, according to the present invention, in an inkjet recording apparatus that performs recording by discharging ink onto a recording material 13 using a recording head having an electrothermal transducer 23 for generating ejection energy, the electrothermal transducer 23 An inkjet recording apparatus is provided, characterized in that it has a head heating means for heating the recording head 10 to a predetermined temperature or higher by applying an electric signal of a higher frequency than the recording frequency to the recording head.

Further, in the above configuration, it is preferable that a temperature detection means 3 of the recording head 10 is provided, and that the electric signal is applied when the detected temperature of the recording head is equal to or lower than the predetermined temperature TA.

FIG. 2 is a flowchart showing the sequence of temperature control operations for the recording head of the inkjet recording apparatus according to the present invention.

In FIG. 2, after turning on the recording device, step 8
By control operations such as Steps 1 to S3, the heater 3 is driven until the head temperature reaches the lowest recordable temperature T, and at the same time the recording frequency fI (driving applied during normal recording) is applied to the electrothermal transducer 23. A driving pulse is given at a higher frequency f2 than the voltage pulse frequency).

3 shows the driving voltage waveform of the electrothermal converter 23 during recording, FIG. 4 shows the driving voltage waveform of the electrothermal converter 23 during head heating according to an embodiment of the present invention, and FIG. 5 shows the driving voltage waveform of the electrothermal converter 23 during recording. The drive voltage waveform of the electrothermal transducer 23 during conventional head heating is shown.

Here, the frequency of the driving voltage pulse during recording is f1=2 and 7 in both the conventional example and the present invention, as shown in FIG.

Further, FIG. 6 is a graph illustrating head temperature versus elapsed time when head heating according to the present invention is performed in comparison with a conventional example.

3 to 6, in this embodiment, the 50W heater 3 is driven, and at the same time f, - as shown in FIG.
4k) (by applying a drive voltage pulse of z to all the electrothermal transducers 23, the recording head 1 is
0 was heated.

The way the head temperature rises in this embodiment is shown by curve 1 in FIG.

On the other hand, in the conventional example, while driving the 50W heater 3, as shown in FIG.
By applying a 2 kHz driving voltage pulse to all the electrothermal transducers 23, the recording head 1 is heated without ejecting ink.
0 was heated.

The way the head temperature rises in this conventional example is explained in the sixth section.
It is shown by the curve ■ in the figure.

In addition, as shown in FIGS. 3 to 5, the electrothermal converter 23
The voltage of the driving voltage pulse was 24 V in all cases, but the pulse width was 10 μsec during recording, and 5 μsec during head heating, a range in which ink was not ejected.

Further, in FIG. 6, the initial temperature of the recording head 10 is T
O = 25°C, and the lowest recordable temperature T is 40°C
It is.

As is clear from the above measurement results, in this example, it took about 2 minutes to reach the recordable temperature T, = 40°C from the initial temperature T, = 25°C, whereas in the conventional example, it took about 2 minutes to reach the recordable temperature, T, = 40°C. It takes about 5 minutes to reach the temperature, and therefore, it can be seen that this example significantly shortened the time for the temperature of the recording head 10 to rise.

FIG. 7 is a diagram showing another waveform of the drive voltage pulse applied to the electrothermal transducer 23 during head heating of the inkjet recording apparatus according to the present invention.

When a burst wave driving voltage as shown in FIG. 7 was applied instead of the waveform shown in FIG. 4, the rise time of the head temperature could be further shortened compared to the case of the above-mentioned embodiment.

In this case, as shown in FIG. 7, the driving voltage waveform has the same voltage value of 24V, and the frequency is f higher than the recording frequency.
2=4 kHz, and the pulse waveform used was a burst wave with a width of 10 μsec, which was within the range in which ink was not ejected.

Curve 2 in FIG. 6 shows the rise characteristic of the head temperature when the drive voltage shown in FIG. 7 is applied to the electrothermal transducer 23. The temperature could be raised to the possible temperature TA=40° C. in about 1 minute, and the rise time could be further shortened.

According to the embodiments described above, in the inkjet recording apparatus, by quickly raising the temperature of the recording head to a temperature at which printing is possible, the waiting time after the apparatus is powered on can be significantly shortened.

Note that in the inkjet recording apparatus, pressurized ink circulation processing may be performed in order to recover from ink ejection failure.

Even after this pressurized ink circulation process, the temperature of the print head IO may drop suddenly and become unable to print.

Even in such a case, by performing the recording head heating operation according to the present invention described above, it was possible to quickly raise the temperature of the recording head 10 to a temperature at which recording was possible.

Note that in the above embodiments, the present invention is applied to a line type inkjet recording apparatus using a full multi-type recording head 10 that covers the recording area in the paper width direction of the recording material 13. However, the present invention can be similarly applied to inkjet recording apparatuses of other recording methods, such as serial scan type inkjet recording apparatuses in which a recording head is mounted on a carriage, and can achieve similar effects. It is.

Furthermore, in the above embodiments, the case of a color inkjet recording apparatus using four recording heads 10 has been described, but the present invention is applicable to monochrome recording using one recording head,
Alternatively, the present invention can be similarly applied to an inkjet recording device for gradation recording using a plurality of recording heads with the same color but different densities, regardless of the number of recording heads, and can achieve the same effects.

The present invention brings about excellent effects particularly in an inkjet recording apparatus using an inkjet recording head of the bubble jet method proposed by Canon Co., Ltd. among inkjet recording methods.

As for typical configurations and principles thereof, it is preferable to use the basic principles disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796.

This method can be applied to both the so-called on-demand type and the continuous type, but especially in the case of the on-demand type, it is necessary to place the liquid (ink) on the sheet or liquid path where it is held. By applying at least one drive signal that corresponds to recorded information and causes a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, the electrothermal transducer generates thermal energy, and the recording head This is effective because it causes film boiling on the heat acting surface of the liquid (ink), resulting in the formation of bubbles in the liquid (ink) in one-to-one correspondence with this drive signal.

Due to the growth and contraction of these bubbles, liquid (
ink) to form at least one droplet.

If this drive signal is in the form of a pulse, bubble growth and contraction will occur immediately and appropriately, so liquids with particularly excellent responsiveness (
As a more preferable pulse-shaped drive signal that can achieve ejection of ink, those described in US Pat. No. 4,463,359 and US Pat. No. 4,345,262 are suitable.

Further, if the conditions described in US Pat. No. 4,313,124 concerning the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be achieved.

The configuration of the recording head includes, in addition to the combined configuration of ejection ports, liquid paths, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, a heat acting section. US Pat. No. 4,558,333 and US Pat. No. 4,459,600 disclose a configuration in which the
The present invention also includes a configuration using the specification of the above specification.

In addition, Japanese Patent Application Laid-open No. 123670 of 1982 discloses a configuration in which a common slit is used as a discharge part for a plurality of electrothermal converters, and a hole that absorbs pressure waves of thermal energy is disclosed. The present invention is also effective as a configuration based on Japanese Patent Application Laid-Open No. 138461 of 1981, which discloses a configuration in which a discharge portion corresponds to a discharge portion.

Furthermore, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus can be produced by combining a plurality of recording heads as disclosed in the above-mentioned specification. , a configuration that satisfies that length or a configuration as a single recording head formed integrally may be used, but the present invention can more effectively exhibit the above-mentioned effects.

In addition, a replaceable chip-type recording head that is attached to the device body enables electrical connection to the device body and ink supply from the device body, or a chip-type recording head that is installed integrally with the recording head itself. The present invention is also effective when using a cartridge type recording nozzle.

Further, it is preferable to add recovery means, preliminary auxiliary means, etc. for the recording head, which are provided as a configuration of the recording apparatus of the present invention, because the effects of the present invention can be further stabilized.

Specifically, for record and 7 do,
Camping means, cleaning means, pressurizing or suction means, preheating means using an electrothermal converter or another heating element, or a combination thereof, preliminary ejection v-1 for ejecting other than recording. ' is also stable and effective for recording data.

Furthermore, the recording mode of the recording apparatus is not limited to a recording mode for only mainstream colors such as black, but may also be configured by integrally configuring the recording head or by a combination of a plurality of recording heads; The present invention is also extremely effective for devices equipped with at least one full color by color mixture.

In the embodiments of the present invention described above, the ink is described as a liquid in L2, but it is an ink that solidifies at room temperature or lower, and may be softened or liquid at room temperature, or in the above-mentioned inkjet, the ink itself is 'C or higher 70''
-S is the one in which the temperature is adjusted within the range below C so that the viscosity of the ink is within the stable ejection range, so it is sufficient if the ink is in a liquid state when the recording signal is applied.

In addition, it can be prevented by actively using the M temperature caused by thermal energy as energy to transform the ink from a solid state to a liquid state, or by preventing ink from solidifying when left for the purpose of preventing ink evaporation. In any case, the ink may be liquefied by the addition of heat energy in response to the recording signal and ejected as liquid ink, or the ink may already begin to solidify by the time it reaches the recording material. Note that the use of ink that is liquefied only by thermal energy is also applicable to the present invention.

In such a case, as in Japanese Patent Application Laid-open No. 54-56847, the ink is held as a liquid or solid in the recesses or through holes of the porous sheet and is placed facing the electrothermal transducer. It may be a form of L7.

In the present invention, the most effective method for the above-mentioned inks is the one that implements the above-mentioned film boiling method.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, in an inkjet recording apparatus that performs recording by ejecting ink onto a recording material using a recording head having an electrothermal transducer for generating ejection energy, The structure includes a head heating means that heats the recording head to a predetermined temperature or higher by applying an electric signal with a frequency higher than the recording frequency to the electrothermal transducer, so that the temperature at which recording can be made is possible. The present invention provides an ink-end printing apparatus that can quickly raise the temperature to 1000 ml and can significantly shorten the waiting time after the printing apparatus is powered on.

According to the second aspect of the present invention, in the above structure, a recording head temperature detection means is provided, and the electrical signal is applied when the detected temperature of the recording head is below the predetermined temperature. An ink-end recording device is provided that can efficiently control the heating movement of the recording gutter.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing a configuration example of a print head of an inkjet printing apparatus according to the present invention, FIG. Figure 5 shows the drive voltage waveform applied to the electrothermal transducer of the recording head, Figure 3 shows the waveform during recording, Figure 4 shows the waveform when heating the conventional recording head, and Figure 5 shows the waveform of the conventional recording head. A voltage waveform diagram showing waveforms during heating of the recording head in an embodiment of the invention,
FIG. 6 is a graph showing the temperature during heating of the recording head in the inkjet recording apparatus of the present invention in comparison with the conventional example, and FIG. 7 is a graph showing the drive voltage waveform during heating of the recording head in another embodiment of the present invention. 8 is a schematic perspective view showing the main part configuration of an inkjet recording apparatus suitable for applying the present invention, and FIG. 9 is a schematic partially broken view illustrating the structure of the recording head in FIG. 8. FIG. Below, symbols representing main components in the drawings are listed. 1-- Recording head body, 2-- Heat vibrator, 3-- Heater, 4-- Heat dissipation fin, 5----- Fan , 6---Temperature detection means, 10.108k, 10Y, 10M, 1
0 C-----1 recording head, 11.12 conveyance means,
13--1-- Recording material, 16-- Non-ejection recovery means, 17-- Head mounting section, 21...
・Discharge port, 23...--Electrothermal converter, 28...
--- Common liquid chamber, 30 --- Liquid path, 31 --- Discharge port surface.

Claims (3)

[Claims] (1) In an inkjet recording apparatus that performs recording by ejecting ink onto a recording material using a recording head having an electrothermal transducer for generating ejection energy, the electrothermal transducer has a frequency higher than the recording frequency. An inkjet recording apparatus comprising a head heating means for heating the recording head to a predetermined temperature or higher by applying an electric signal. (2) The inkjet recording apparatus according to claim 1, wherein the head heating means applies the electric signal when the detected temperature of the recording head is equal to or lower than the predetermined temperature. (3) The inkjet according to claim 1 or 2, wherein the recording head ejects ink from an ejection port by the growth of bubbles due to film boiling caused by thermal energy applied by the electrothermal converter. Recording device.