JP2840480B2 - INK JET RECORDING APPARATUS AND RECORDING METHOD THEREOF - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus and its driving method.

[0002] In particular, the present invention relates to a recording apparatus and a driving method capable of high-speed recording.

(Description of Related Art) A typical example of an ink-jet recording apparatus is that a drive signal corresponding to an image or character information signal is applied to an electrothermal transducer to generate heat, thereby causing a heat-generating portion (hereinafter also referred to as a heater) to be generated. Electricity is a heat energy generator that generates heat energy used to discharge the ink by heating the surrounding ink to give a state change accompanied by foaming to the ink, and discharging the ink by the pressure generated at that time. A heat converter and an ink path (hereinafter also referred to as a nozzle) communicating with a discharge port (hereinafter also referred to as an orifice) for discharging ink are provided.

[0004] As a driving method of such an ink jet recording apparatus, Japanese Patent Application Laid-Open No. Sho 55-10 filed earlier by the present applicant has been proposed.
As described in the related art of No. 9672, there is a problem that recording droplets ejected from adjacent nozzles buffer each other and deteriorate print quality. To solve these problems, conventionally, a plurality of heaters are block-driven to reduce the number of heaters to be driven at the same time, and also to prevent buffering of recording droplets ejected from adjacent nozzles.

[0005]

However, in the above-described conventional example, when ink is ejected from a small number of nozzles, refilling of ink after ejection and return of the meniscus are performed in a short time. At the time of ejection, there is a problem that the ejection is delayed. In this case, as an example, the refill frequency is reduced from 8 KHz to about 4 KHz. Usually, the lowest dischargeable repetition frequency is set as the upper limit of the drive frequency of the apparatus. Therefore, in these cases, there is a problem to be solved in that it is difficult to perform high-speed printing at a high drive frequency.

[0006]

The inventor of the present invention has observed the phenomenon at the time of multi-ejection and performed various experiments. As a result, the refill time was reduced by appropriately setting the pause time between each group of the divided drive. We have found a method of shortening and greatly improving the discharge repetition frequency during multiple discharges.

According to a recording method of the present invention for solving the above-mentioned problems, a plurality of ejection openings for ejecting ink, ink passages provided corresponding to the plurality of ejection openings, and ink in the ink passage are provided. Heat energy generating means for generating heat energy for generating bubbles by heating the plurality of heat energy generating means, and dividing the plurality of heat energy generating means into a plurality of groups, and generating the heat energy in the heat energy generating means of each group. A signal supply unit for supplying a signal for causing each of the groups to have a signal, wherein the driving method is such that the size of the bubble is maximized when the signal is supplied. In the meantime, the signal is supplied to the next group of thermal energy generating means.

According to another aspect of the present invention, there is provided a recording apparatus that discharges ink, an ink path provided corresponding to the discharge port, and heats the ink in the ink path. An ink jet recording head comprising a thermal energy generating means for generating thermal energy for generating bubbles, and dividing a plurality of the thermal energy generating means into a plurality of groups; A signal supply unit for supplying a signal for generating thermal energy to the next group of thermal energy generating units until the bubble size is maximized by supplying the signal; And a transport for transporting the medium.

That is, according to the present invention, when a plurality of heaters are divided into a plurality of groups and driven, a certain group of heaters is energized (signal is applied), and bubbles (hereinafter, also referred to as bubbles) are generated. From the point of time to the time of maximum foaming, the energizing pulse is applied to the electrothermal transducers in the next group in the series to improve the ink refill time and increase the frequency of printable recording droplets Can be done. Further, by continuously stabilizing the process from foaming to defoaming of each group at the time of ejection from a large number of nozzles, displacement of the landing position of recording droplets on the recording medium is reduced, and print quality is improved. It can also be improved.

[0010]

Embodiments of the present invention for improving refill characteristics will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an example of a drive control system according to the present invention. Reference numeral 21 denotes a head drive circuit according to the present invention, which includes a head drive power supply 22 and a timing generation circuit 2.
3, a print data transfer circuit 24 and a print data / drive timing generation circuit 25 are provided. Here, the timing generation circuit 23 generates a pulse width setting signal EN according to the control signals C ₁ and C ₂ of the recording data / drive timing generation circuit 25.
B, a selection signal SEL for selecting a latch position of input print data and selecting an electrothermal transducer to be driven
1 to SEL4 and a latch signal LAT2 are generated. The print data transfer circuit 24 extracts and reorganizes the print data for one line, and supplies the data to the print head drive IC 26.

FIG. 2 is a diagram showing the drive timing according to the embodiment of the present invention. The recording data SI1 for one line composed of the same number of bits as the electrothermal transducer is re-incorporated into the recording data SI2 corresponding to the electrothermal transducer (heater) driven simultaneously by the recording data division generating circuit, and the recording head Is forwarded to After that, the data is read into the latch circuit in the drive IC selected by SEL1 to SEL4 in response to the input of the line signal LAT2. Thereafter, energization of the electrothermal transducer selected by the input of the ENB signal is performed. The data transfer, the selection signal, and the input of the pulse width setting signal are repeated a predetermined number of times to print one line.

FIGS. 3A and 3B are diagrams showing the driving order of each nozzle in one embodiment of the driving method according to the present invention. In the drawing, reference numeral 41 denotes an ink jet recording head. In this embodiment, a head having a fluid resistance element in an ink path is used. Reference numeral 42 denotes a flight path of the recording liquid.
In this embodiment, each nozzle of the ink jet recording head is divided into four groups as a series,
As shown in the drive pulse in the figure, the No. 1,
The electrothermal transducers belonging to each group are sequentially driven with a time difference of Td in the order of 2, 3, and 4.

FIG. 14 shows the correspondence between the value of the drive pulse time difference Td of the electrothermal transducers divided into groups and the average value of the response frequencies of all nozzles at the time of all ejections. In the drawing, the case where the fluid resistance element is not provided (pulse width 7 μm) is indicated by a broken line. As can be seen from the figure, in the response frequency change corresponding to Td, the response frequency is high in the range of Td from the bubble foaming start time to the maximum foaming time. Thus, in the range from the start of foaming to the maximum foaming, the response frequency of each nozzle can be improved by applying an energizing pulse to the next group of electrothermal transducers. If Td is made longer than the maximum bubble generation time, the response frequency (refill characteristic) decreases, and the landing position of the recording droplet on the recording medium shifts, resulting in poor print quality. Deteriorates.

As described above, it is considered that the response frequency is improved when the next group is driven by the time of the maximum foaming as follows.

Hitherto, the application of the drive signal to each group has been performed after the bubble defoaming process. However, in such a driving method, there is a nozzle in which ink flows backward from the nozzle to the common ink chamber due to foaming near the nozzle where ink is refilled from the common ink chamber to the nozzle at the time of defoaming. Turbulence occurs near the ink supply port to the nozzle, which hinders refilling of the ink into the nozzle during bubble elimination. Therefore, by driving the next group by the time of the maximum foaming, it is considered that a high response frequency can be obtained by synchronizing the flow of ink from the nozzles to the common ink chamber as much as possible.

When a flow resistance element having a flow resistance downstream (refill direction) smaller than the flow resistance upstream is provided in the nozzle, the flow flowing from the nozzle into the common liquid chamber during foaming should be sufficiently reduced. Therefore, the response frequency can be further improved.

In the experiment of the inventor of the present invention, a 360 DPI, 64 nozzle head was used, and the pulse width was 3 μs, 4 groups each had 16 nozzles,
When printing was performed at 6.5 KHz, when Td exceeded the range of 1 to 5 μs, the landing position shift began to be noticeable, and the time until the maximum foaming (about 8 μs) was judged to be the allowable limit. FIG. 5 is a graph showing the results of measuring the ejection speed of the droplets from each nozzle under the above printing conditions.

According to this graph, the above-mentioned Td = 1 to 5 μs
In the range, the average discharge speed of each nozzle is as fast as 12.4 m / s, and the dispersion of the discharge speed is small and stable. Td
= 9 μs or more, the average discharge speed is 9.1 m / s and T
This is lower than that of d = 1 to 5 μs, and the variation in the ejection speed of each nozzle is largely unstable.

From the above, in order to keep the ejection repetition frequency high when ejecting ink from a large number of nozzles and to improve the impact point accuracy, energization of the next group is started between the foaming start time and the maximum foaming time. Is appropriate. More preferably, energization of the next group is started within 1 to 5 μs after the start of foaming.

FIGS. 6A and 6B are views for explaining another embodiment of the present invention. In the driving pulses in the drawing, the numbers in parentheses indicate the order in which the driving pulses are applied. In the drawing, the driving pulses are applied to the electrothermal transducer in the order of 1, 2, 3, and 4.

7A and 7B are views for explaining another embodiment of the present invention. In the figure, drive pulses are applied to the electrothermal transducer in the order of 1, 2, 3, and 4.

In both of these drawing groups,
As in the case of FIG. 3, the refill timing between the neighboring nozzles is synchronized as much as possible, and the energization pulse is started to be applied to the next group of electrothermal transducers from the start of foaming to the time of maximum foaming. And the ejection speed can be stabilized to improve the landing accuracy.

Although the driving method of the present invention has an effect as shown by the broken line in FIG. 4 even when the fluid resistance element is not provided, a great effect can be obtained by using the fluid resistance element in the nozzle. it can.

FIG. 8 is a perspective view schematically showing an example of an ink jet recording head provided with a fluid resistance portion having a locally reduced cross-sectional area in the direction of the upstream side (common liquid chamber side) of the heater according to the present invention. is there.

In the drawing, reference numeral 11 denotes a heat-generating portion (discharge heater) of an electrothermal converter as a heat energy generator for generating heat by energization (application of a drive signal) to cause a bubbling phenomenon in the ink to discharge the ink. ). Reference numeral 12 denotes a substrate, and the heat generating portion 11 is formed on the substrate through a manufacturing process similar to a semiconductor manufacturing process. Reference numeral 13 denotes an ink discharge port, which is shown with the same cross-sectional area as that of the flow path for simplification. Reference numeral 14 denotes an ink path communicating with the ejection port 13. A portion 18 provided in the ink path 14 is a fluid resistance portion for locally reducing the cross-sectional area of the nozzle. Reference numeral 15 denotes an ink path forming member for forming the ejection port 13 and the ink path 14, and 16 denotes a top plate. Reference numeral 17 denotes an ink chamber which is common to the ink paths 14 and communicates with each other.

In the case where the recording method of the present invention is used using a head having a fluid resistance element for the ink path, the position where the fluid resistance element is provided (between the heater and the concentrated resistance element (μ
FIG. 9 shows the relationship between m)) and the response frequency.

As shown in the figure, it can be understood that the response frequency can be increased when a fluid resistance element (fluid resistance section) is provided near the heater, and the fluid resistance element section is provided. The cross-sectional area of the bubble is small, and the foamed bubble is divided on the common liquid chamber side (upstream side where the ink flows) from the heater, and the effect is further enhanced in the head that can be formed.

In the present embodiment for driving a head having a fluid resistance element, the fluid resistance portion is located at a position facing two surfaces different from the heater as shown in FIG. An example is shown in which the flow resistance in the direction toward the discharge port (downstream direction) is smaller than that in the opposite direction (upstream direction), but without being limited to such a shape, A single surface or a plurality of surfaces may be provided on the same surface as the heater upstream of the heater, the surface facing the heater surface, the center of the ink path, or the like.

FIG. 10 is a perspective view schematically showing the external structure of an ink jet recording apparatus that performs the driving method of the present invention. In FIG. 10, reference numeral 1 denotes an ink jet recording head (hereinafter, referred to as a recording head) that discharges ink based on a predetermined recording signal and records a desired image, and 2 denotes a recording row direction (main scanning) on which the recording head 1 is mounted. Direction). The carriage 2 includes a guide shaft 3,
4 and slidably supported, and reciprocates in the main scanning direction in conjunction with the timing belt 8. Pulley 6,
The timing belt 8 engaged with the pulley 7
, And is driven by the carriage motor 5.

The recording paper 9 is guided by a paper bun 10 and conveyed by a paper feed roller (not shown) compressed by a pinch roller. This conveyance is performed using the paper feed motor 16 as a drive source. The transported recording paper 9 is tensioned by a paper discharge roller 13 and a spur 14, and a paper pressing plate 12 formed of an elastic member.
Therefore, the sheet is conveyed while being in close contact with the heater 11. The recording paper 9 to which the ink ejected by the head 1 has adhered is heated by the heater 11, and the adhered ink evaporates the solvent and is fixed on the recording paper 9. The heating and fixing by the heater 11 is not always necessary, and may be provided in the recording apparatus as appropriate depending on the characteristics of the ink and the like.

Numeral 15 denotes a unit called a recovery system, which removes foreign substances and ink with increased viscosity attached to the discharge ports (not shown) of the recording head 1 to maintain the discharge characteristics in a normal state. belongs to.

Reference numeral 18a denotes a cap which constitutes a part of the recovery system unit 15, which caps the discharge port of the ink jet recording head 1 to prevent clogging. An ink breathing body 18 is arranged inside the cap 18a.

On the recording area side of the recovery system unit 15, there is provided a cleaning blade 17 for contacting the surface of the recording head 1 on which the discharge port is formed and cleaning foreign substances and ink droplets adhered to the discharge port surface. Have been.

The present invention particularly provides an excellent effect in a recording head and a recording apparatus of an ink jet recording system in which flying droplets are formed by utilizing thermal energy to perform recording, among the ink jet recording systems.

The typical configuration and principle thereof are described in, for example, US Pat. Nos. 4,723,129 and 47407.
No. 96, and the present invention is preferably carried out using these basic principles. This recording method can be applied to both so-called on-demand type and continuous type.

The recording method will be described briefly. An electrothermal transducer disposed corresponding to a sheet or a liquid path holding a liquid (ink) and a liquid (ink) corresponding to recording information are used. Heat energy is generated by applying at least one drive signal for providing a rapid temperature rise that exceeds the nucleate boiling phenomenon and causes a film boiling phenomenon, thereby causing film boiling on the heat-acting surface of the recording head. . As described above, since bubbles corresponding to the drive signal applied to the electrothermal converter from the liquid (ink) can be formed one-to-one, it is particularly effective for an on-demand type recording method. By discharging the liquid (ink) through the discharge hole by the growth and shrinkage of the bubble,
Form at least one drop. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. Examples of the drive signal in the form of a pulse include U.S. Pat. Nos. 4,463,359 and 4,345.
No. 262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise of the heat acting surface are adopted, more excellent recording can be performed.

The structure of the recording head is a combination of a discharge hole, a liquid flow path, and an electrothermal converter (a linear liquid flow path or a right-angle liquid flow path) as disclosed in the above-mentioned respective specifications. In addition, as disclosed in U.S. Pat. Nos. 4,558,333 and 4,459,600,
The present invention also includes a configuration in which the heat acting portion is arranged in a bent region.

In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge hole of an electrothermal transducer for a plurality of electrothermal transducers, or absorbs a pressure wave of thermal energy. The present invention is also effective in a configuration based on JP-A-59-138461, which discloses a configuration in which the opening to be made corresponds to the discharge section.

Further, as a recording head in which the present invention is effectively used, there is a full-line type recording head having a length corresponding to the maximum width of a recording medium on which recording can be left unrecorded. The full line head may be a full line configuration by combining a plurality of recording heads as disclosed in the above specification, or may be a single full line recording head formed integrally.

In addition, the print head is exchangeable with a print head of a chip type, which can be electrically connected to the main body of the apparatus or supplied with ink from the main body of the apparatus, or is integrated with the print head itself. The present invention is also effective when a cartridge-type recording head provided in a fixed manner is used.

It is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like to the recording apparatus of the present invention because the recording apparatus of the present invention can be further stabilized. More specifically, preheating of the recording head by capping means, cleaning means, pressurizing or suction means, an electrothermal transducer or another heating element, or a combination thereof. Means and means for performing a preliminary ejection mode for performing ejection that is different from printing are also effective in performing stable printing.

Further, the recording mode of the recording apparatus is not limited to a mode for recording only a mainstream color such as black, but may be a mode in which a recording head is integrally formed or a combination of a plurality of recording heads. However, the present invention is also very effective for an apparatus provided with at least one of multiple colors of different colors or full color by mixing colors.

In the embodiments of the present invention described above, the description is made by using the liquid ink. However, in the present invention, the ink which is solid at room temperature or the ink which becomes soft at room temperature is used. Can be used. In general, in the above-described ink jet device, the temperature of the ink itself is adjusted within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. It is sufficient if the ink is in a liquid state.

In addition, the excessive rise of the temperature of the head or the ink due to the thermal energy is used as energy for changing the state of the ink from the solid state to the liquid state, thereby positively preventing the ink or the ink from evaporating. For the purpose, an ink that solidifies in a standing state can be used. In any case, the ink is liquefied for the first time by the application of heat energy, such as one in which the ink is liquefied and ejected as an ink liquid by application of the heat energy according to the recording signal, or one which already starts to solidify when reaching the recording medium. The use of an ink having the following properties is also applicable to the present invention.

Such an ink is disclosed in JP-A-54-568.
No. 47 or Japanese Unexamined Patent Publication No. Sho 60-71260, in a state where it is held as a liquid or solid substance in a concave portion or a through hole of a porous sheet and faces an electrothermal converter. It is good also as a form.

In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, the form of the ink jet recording apparatus of the present invention is not limited to the one used as an image output terminal of an information processing apparatus such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function. It may take a form.

[0049]

By using the method of driving the ink jet recording apparatus of the present invention, the frequency at which recording liquid droplets can be ejected when each nozzle ejects simultaneously can be greatly improved, and the recording speed can be improved. become.

By eliminating variations in the ejection speed of the droplets ejected from each nozzle and stabilizing the ejection speed,
Improves impact point accuracy and enables high quality printing.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a drive control system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating drive timing according to an embodiment of the present invention.

FIGS. 3A and 3B are diagrams showing a driving order of each nozzle in the embodiment of the present invention.

FIG. 4 shows a drive pulse time difference Td according to an embodiment of the present invention.
7 is a graph showing the correspondence between the response frequency and the response frequency.

FIG. 5 is a diagram showing a drive timing and a droplet discharge speed.

FIGS. 6A and 6B are diagrams for illustrating another embodiment of the present invention.

FIGS. 7A and 7B are diagrams showing another embodiment of the present invention.

FIG. 8 is a schematic perspective view showing an example of an ink jet recording head provided with a fluid resistance portion to which the recording method of the present invention is applied.

FIG. 9 is a diagram showing a position and a response frequency of a fluid resistance element in a nozzle to which the driving method of the present invention is applied.

FIG. 10 is a perspective view illustrating an example of a recording apparatus to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Heat generation part of electrothermal transducer 12 Substrate 13 Discharge port 14 Ink path 15 Ink path forming member 16 Top plate 17 Ink chamber 18 Fluid resistance part 21 Head drive circuit 22 Head drive power supply 23 Timing generation circuit 24 Print data transfer circuit 25 Print data drive timing generation circuit 26 Drive IC 41 Ink jet print head 42 Flight path of print droplet

Claims (10)

(57) [Claims] A plurality of ejection openings for ejecting ink, ink passages provided corresponding to the plurality of ejection openings, and heat energy for heating ink in the ink passages to generate bubbles. Heat energy generating means to be generated, and a plurality of the heat energy generating means divided into a plurality of groups, and a signal supply means for supplying a signal for generating the heat energy to the heat energy generating means of each group for each group A method for driving the next group of thermal energy generating means until the size of the bubble is maximized by supplying the signal. A recording method for an ink jet recording apparatus, comprising: 2. The recording method according to claim 1, wherein the thermal energy generator is an electrothermal converter. 3. The signal supply means supplies a signal such that a time between supply of the signal to a group to be driven next in a series of group drive is 1 μs or more and 5 μs or less. 3. The method for driving an ink jet recording apparatus according to item 1. 4. The driving method for an ink jet recording apparatus according to claim 1, wherein the signals supplied for each group are supplied to thermal energy generating means arranged in a row. 5. The method according to claim 1, wherein the ink path has a fluid resistance portion. 6. The ink path includes a fluid resistance portion upstream of the thermal energy generating means for minimizing a cross-sectional area of the ink path to divide the bubbles.
Driving method of an ink jet recording apparatus. 7. A discharge port for discharging ink, an ink path provided corresponding to the discharge port, and thermal energy generation for generating heat energy for heating ink in the ink path to generate bubbles. Means for dividing the plurality of the thermal energy generating means into a plurality of groups, and supplying a signal for generating the thermal energy to the thermal energy generating means in each group. The signal supply means for supplying to the next group of thermal energy generating means until the size of the bubble becomes maximum, and the conveyance for conveying the recording medium. Inkjet recording apparatus. 8. An ink jet recording apparatus according to claim 7, wherein said ink path has a fluid resistance portion upstream of said thermal energy generating means. 9. The ink jet recording apparatus according to claim 7, wherein the ink path includes a fluid resistance portion facing two surfaces different from the surface on which the thermal energy generating means is arranged. 10. The ink jet recording apparatus according to claim 8, wherein said fluid resistance portion is a fluid resistance portion for dividing said air bubbles.