JPH10777A - Recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold good recording quality by controlling the emitting amt. of ink from a recording head to be constant by discriminating the kind of input recording data from the outside and regulating the internal temp. and drive frequency of the recording head according to the descrimination result. SOLUTION: A CPU controls the temp. of a recording head to 25 deg.C through an I/O controller (S1). Processing becomes the input waiting state of recording data (S2). Next, when data is inputted through PPI, the CPU investigates the kind of an image on the basis of the density of the pixels of the image to be recorded (S31). When the kind of the input recording data is judged to be character data reduced in the emitting amt. of ink, the keeping temp. of the recording head is set to 40 deg.C and drive frequency emitting ink from the recording head is set to 6.25kHz (S4). By this constitution, a current is supplied to the heating/temp. holding heater within the recording head and the temp. in the recording head rises. Thereafter, recording operation is performed in recording density of 360dpi (S6).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus, and more particularly, to a recording apparatus having a recording head for performing recording according to an ink jet system.

[0002]

2. Description of the Related Art Conventionally, a recording apparatus using an ink jet recording head has been widely used in business offices and other office processing departments where quietness is required, because of its reputation for non-impact recording. In addition, high-speed recording at high density is possible and its maintenance is relatively easy.

[0003] Such a recording apparatus generally includes a recording head that heats ink, causes a displacement accompanied by a sudden increase in volume of the ink, and discharges ink droplets from an ink discharge nozzle (hereinafter, referred to as a nozzle). Have. The recording head includes an electrothermal converter (hereinafter, referred to as a heater) capable of heating the ink by generating heat by an externally applied current in order to form ink droplets.

In this printing apparatus, temperature control is performed such as keeping the temperature of the print head constant, because the ink ejection characteristics change with the temperature of the print head, and in particular, the diameter of the ink droplet changes. . Therefore, a temperature sensor is provided in the recording head. However, in a recording head that ejects ink droplets using thermal energy,
Due to its structure, the print head itself generates heat by the printing operation, and in particular, the ink temperature in the nozzle having the heater becomes higher than the temperature detected by the temperature sensor during the printing operation. The degree differs depending on the recording pattern and the recording density.

[0005] Therefore, when an image having a high recording density is generally recorded over the entire recording paper such as a natural image having a gradation, the ink temperature in the nozzle is high and the density of the recorded image tends to be high. There is. On the other hand, when recording an image having a relatively low recording density in terms of the area of the entire recording paper such as a character image, the density of the recorded image tends to be low. Therefore, it is very difficult to always maintain the same density of the recorded image.

When an image such as a natural image is printed, multi-pass printing control is sometimes performed to improve the image quality. However, even when such control is performed, the printing density at each scan is reduced. Because of the difference, the temperature rise of the print head is also biased, and this may appear as a difference in print density. Further, if the recording density at each scan is different, the degree of penetration of the ink into the recording medium is different, and this appears as a density difference of the recorded image. For example, compared to the case where high-density printing is performed in one scan without performing multi-pass control, the case where printing is performed a plurality of times in the same area at a relatively low printing density by multi-pass control is performed. However, since the lateral spread of the individual ink droplets on the recording medium is small, the apparent recording density is low.

In order to solve such a problem, for example, according to the technique disclosed in Japanese Patent Application Laid-Open No. Hei 5-31886, a difference in recording density due to a difference in recording mode (character image recording and natural image recording) is disclosed. In order to eliminate the problem, the ink ejection amount is controlled according to the mode.

[0008]

However, in the above-mentioned prior art, a single recording head is used to discharge ink droplets in accordance with a recording mode, that is, in order to achieve high-speed recording in the case of character image recording. In order to achieve both ejection of ink droplets for forming large-diameter pixels and ejection of ink droplets for forming small-dot-diameter pixels in order to achieve high resolution in the case of natural image recording, ink Since the ejection amount is controlled, the refill cycle of the ink from the ink tank to the nozzles is different as described in JP-A-6-191028. There is a problem that the ink droplets are not sufficiently large, and as a result, the recording pixels are blurred.

This is because, when ink is ejected at high speed and continuously, before the ink liquid level returns to a normal meniscus state at the orifice of the recording head after the ejection of the ink droplet, the ink liquid level is changed to the recording head. The orifice performs the ejection operation in a raised state, and a phenomenon occurs that the ink droplet does not fly normally from the orifice due to the surface tension of the ink, but rather the ink spreads to the side surface of the orifice. It is.

The present invention has been made in view of the above-mentioned conventional example, and has as its object to provide a recording apparatus capable of performing high-quality recording when recording any kind of image data.

[0011]

In order to achieve the above object, a recording apparatus according to the present invention has the following arrangement.

That is, the present invention is a recording apparatus for recording on a recording medium by discharging the ink by heating the ink by supplying a current to a plurality of electrothermal transducers provided in the recording head. Input means for inputting the print head, temperature adjusting means for adjusting the internal temperature of the print head, drive means for driving the print head, determining means for determining the type of print data input by the input means, The internal temperature of the recording head and the driving frequency of the recording head are adjusted via the temperature adjusting unit and the driving unit according to the result of the determination by the determining unit, and the amount of ink ejected from the recording head is controlled. And a control device.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With the above arrangement, the present invention provides a method for recording on a recording medium by discharging ink by energizing a plurality of electrothermal transducers provided in a recording head to heat the ink. The type of the print data input from the outside is determined, and the internal temperature of the print head and the drive frequency of the print head are adjusted according to the determination result to control the amount of ink ejected from the print head.

In order to adjust the temperature of the recording head, for example, a measuring means for measuring the internal temperature using a thermistor or the like and a heating means for heating the inside using a heater or the like are used.

The type of input recording data is determined by determining the density of pixels of an image recorded by the input recording data. Further, it is determined whether to record the input recording data at a high resolution or a low resolution according to the sparse density of the pixel. Here, print data recorded at a high resolution includes an image having a large amount of ink ejected per unit area of a recording medium, and print data recorded at a low resolution includes an image having an ink ejected amount per unit area of a recording medium. Character images with few characters.

Further, in the control of the ink discharge amount, when input print data is printed at a high resolution, the internal temperature of the print head is kept relatively low and the drive frequency of the print head is raised relatively. On the other hand, when input recording data is recorded at a low resolution, control is performed such that the internal temperature of the recording head is kept relatively high and the driving frequency of the recording head is made relatively low.

Further, the driving of the recording head is
A plurality of electrothermal transducers may be divided into a plurality of blocks, and each block may be energized and driven.

Further, the recording head includes a plurality of ink ejection nozzles for ejecting ink corresponding to each of the plurality of electrothermal transducers, and the ink ejected from the ink ejection nozzle is ejected from the ink ejection nozzle. The surface tension (γ) at the outlet satisfies γ ≦ 40 (dyne / cm).
In addition, the contact angle (θ) between the discharge port and the ink at the discharge port of the ink discharge nozzle satisfies θ ≦ 90 °.

Further, the ink discharge amount has a characteristic that increases and decreases in proportion to the ink temperature or the recording head temperature.

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a maximum of 720 dpi for recording according to an ink jet system which is a typical embodiment of the present invention.
FIG. 1 is a perspective view illustrating a configuration of a recording apparatus 1 including a recording head capable of recording at a recording density of FIG.

As shown in FIG. 1, the recording head 2 is mounted on a carriage 3 via a head connector 12, and is moved on a sliding shaft 10 by a carriage (CR) motor (not shown) and a carriage driving belt 11. It is reciprocated in the direction of arrow S. In addition, an electric signal from the main board 7 on which the control circuit is mounted is supplied to a flexible printed cable (F
(PC) 6 to the recording head 2.

The ink is supplied from an ink cartridge (not shown) provided inside the recording apparatus 1 to the recording head 2 via the sub-ink tank 4 on the carriage 3 via the ink supply / suction tube 5. You. In the recording head 2, a suction recovery device 8 is provided at the home position of the carriage 3, because the ejection failure of the ink rarely occurs due to the incorporation of bubbles or the adhesion of the ink to the orifice surface. . A recording medium such as recording paper is moved on a platen 9 by a paper feed (LF) motor (not shown) by an arrow C.
Transported in the direction of Therefore, recording of one page of the recording medium is performed by the reciprocating movement of the recording head 2 in the direction of arrow S and the conveyance of the recording medium in the direction of arrow C.

FIG. 2 is a block diagram showing a configuration of a control circuit mounted on the main board 7 of the recording apparatus 1. The control circuit receives, for example, print data from a host computer (not shown: hereinafter, referred to as a host), temporarily stores print data for one scan of the print head, and prints the print head 2 via a head controller 31. Is controlled to perform recording.

In FIG. 2, a PPI (programmable
The peripheral interface (32) receives the parallel recording data sent from the host and sends the received data to the CPU 33. The CPU 33 reads out the control program stored in the ROM 34 and executes various processes related to the recording operation. The CPU 33 stores the received record data transferred from the PPI 32 via the data bus into the RAM 3.
5 is stored in the line buffer memory secured. This line buffer memory can store print data corresponding to the number of scans of the print head. If the received record data is a character code, the CPU 33 refers to the font data stored in the ROM 36 and develops the code into bitmap data. The head controller 31, PPI 32, ROMs 34, 36, RAM 35,
Access from the CPU 33 to the I / O controller 37 and the like and information transfer between these elements are performed via an address bus and a data bus.

The I / O controller 37 has a CPU
Based on a command from the CPU 33, the paper feed (LF) motor 38, the carriage (CR) motor 39, and the suction recovery (pump) motor 40 are controlled via the drivers 44 to 46, respectively. Control of data input / output to / from the panel switch 41, control of the heater 42 provided on the recording head 2 via the driver 47,
The input of temperature information from the thermistor 19 provided in the recording head 2 is controlled via the temperature detection circuit 48. The head controller 31 latches print data and print data output time, and in response to a command from the CPU 33, the print head 2 ejects ink in accordance with the print data and print data output time data, and prints on a print medium. Control to do.

FIG. 3 is a schematic diagram showing the configuration of the recording head 2.

As shown in FIG. 3, an electric wiring board (PCB) 14 and a thermistor 19 are provided on a base plate 13.
In addition, a discharge element 18 including a nozzle for discharging ink, a heater, and an ink liquid chamber is joined.
The print data is supplied to the ejection element 18 via the FPC 6. This supply is performed by engaging the head connector 12 connected to one end of the FPC 6 with the connector section 15 of the electric wiring board (PCB) 14. Also,
The ink is supplied to a holder 16 for protecting the main part of the recording head in which the ink supply pipe 17 and the ink reservoir 20 are integrated.
Is supplied to the discharge element 18 via

FIG. 4 is a perspective view showing a detailed structure of the discharge element 18. As shown in FIG.

As shown in FIG. 4, the heaters 25 and 26 for heating and keeping the head are formed on the Si (silicon) substrate 21 with the same material as the heater 23 for discharging ink. Also,
A thermistor 19 is mounted on the base plate 13, and energization of the head heating / heating heaters 25 and 26 is turned on by head temperature information obtained from the thermistor.
/ OFF control to control the printhead temperature. In FIG. 4, reference numeral 22 denotes 64 orifices from which ink droplets are ejected, 24 denotes 64 nozzles communicating with the orifice 22, and 28 denotes a nozzle for temporarily supplying ink supplied from an ink tank (not shown) to the nozzle 24. The ink chamber 29 for temporarily storing is a filter. Each heater 23, 25, 26 is connected to an electric wiring board (PCB) 14 via an Al (aluminum) wiring 27 by wire bonding 30.

The recording head temperature is controlled by using the head heating / warming heaters 25 and 26 provided separately from the ink discharging heater 23 so that the recording head 2 is maintained at a temperature suitable for a predetermined ink discharging amount. Is done to maintain
It is performed during the recording operation and in a predetermined standby state.

FIG. 5 is a graph showing the relationship between the temperature of the recording head and the ejection amount per ink droplet obtained experimentally. As can be seen from FIG. 5, the discharge amount is about 26 pl / droplet at 25 ° C. and about 40 pl / droplet at 40 ° C. In this temperature range, there is a substantially proportional relationship between the two. At this time,
Table 1 shows the components of the used ink.

[0033]

[Table 1]

[0034] The surface tension (γ) of the ink is about 30 dyne
/ Cm, viscosity (η) is about 1.8 cp (centipoise)
It is. Further, the contact angle between the ink and the orifice is about 60 ° C.

FIG. 6 is a block diagram showing a configuration of a logic circuit of the recording head 2 having 64 recording elements along the transport direction of the recording medium. As shown in FIG. 6, in this logic circuit, one printing element is provided with one heater and one drive transistor (N-Mos transistor) for energizing the heater, which is provided in one nozzle.
The logic circuit includes a Cmos transistor, receives a recording signal (IDATA) from a recording device in accordance with a clock signal (DCLK), and stores a 64-bit signal, and latches the recording signal. A latch circuit 802, a 3 → 8 decoder 803 for generating a block selection signal for driving the 64 nozzles into eight blocks based on a 3-bit block drive signal (BlockENB) input from the printing apparatus, The block drive signal and the energization drive signal (He
atENB) and 64 AND circuits 804 for calculating the logical product of the odd recording element drive signal (OddENB) or the even recording element drive signal (EvenENB) input from the recording apparatus. Further, a diode 805 constituting the temperature sensor 19 and a temperature adjusting sub-heater 806 constituting the head heating / warming heaters 25 and 26 are provided.

In FIG. 6, LTCLK is a latch clock supplied to the latch circuit 802, RESET is a reset signal of the latch circuit 802, Rsub is a control signal for temperature adjustment, DiA is an input signal to the diode 805,
DiK is an output signal from the diode 805.

Next, a description will be given, with reference to the flowchart shown in FIG. 7, of a temperature control process associated with a printing operation using the printing head and the printing apparatus having the above-described configuration.

When the power of the recording apparatus is turned on, first, in step S1, the CPU 33 controls the temperature of the recording head 2 via the I / O controller 37 so as to maintain it at 25.degree. Then, in step S2, the process enters a standby state for inputting print data.

Next, when recording data is input from the host via the PPI 32, the process proceeds to step S3, where C
The PU 33 checks the type of the image based on the density of pixels of the image recorded by the input recording data. That is, if the ink ejection amount per unit area of the recording paper is large and the density of pixels is high, it is determined that the image is a natural image or a photograph, while the ink ejection amount per unit area of the recording sheet is small. If the pixel density is low, it is determined that the image is a character (text) image.

If it is determined that the type of the input print data is character data with a small amount of ink ejected per unit area of the print sheet, the process proceeds to step S4, in which the temperature of the print head is maintained. At 40 ° C., the driving frequency for generating ink discharge from the recording head is 6.25 KHz.
Set to. Thus, the heaters 25 and 26 in the recording head 2 are energized, and the temperature in the recording head rises. Thereafter, the process proceeds to step S5, and FIG.
The recording operation is performed at a recording density of 360 dpi by using all 64 heaters indicated by. At this time, these 64 heaters are divided into 16 blocks (8 × 2 (odd / even recording element) blocks), and a maximum of four droplets are ejected at a time. Note that the operation time per recording operation cycle is 160 μs.
In order to divide the ee into 16 blocks, the heat signal is input so as to fit in a section of 10 μsee per block. At this time, the input heat signal may be a single pulse or may be divided into several pulses and input. By such recording control, the arrangement of each pixel to be recorded is as shown in FIG.

On the other hand, if the type of the input recording data is determined to be image data such as a natural image or a photograph having a large ink ejection amount per unit area of the recording paper,
The process proceeds to step S6, in which the print head temperature is kept at 25 ° C., and the drive frequency for generating ink discharge from the print head is set to 7.38 KHz. Thereafter, the process proceeds to step S5, and the recording operation is performed at a recording density of 720 dpi using 32 heaters out of the 64 heaters shown in FIG. At that time, these 32 heaters were
It is divided into blocks, and a maximum of four droplets are ejected at a time. The operation time per recording cycle is 135 μs.
16 μs per block to divide ee into 8 blocks
The heat signal is input into ee so as to be contained. At this time, the input heat signal may be a single pulse or may be divided into several pulses and input.
By such recording control, the arrangement of each pixel to be recorded is as shown in FIG.

Therefore, according to the embodiment described above, in the case of printing a character having a low recording density, the temperature of the recording head is increased to increase the amount of ink discharged per discharge, while an image having a high recording density is formed. In the case of printing, since the temperature of the print head is relatively low and the amount of ink discharged per discharge is controlled to be small, the image density in printing at high printing density and printing at low printing density are the same. It can be. Further, in the case of performing recording with a high recording density, the driving frequency is set to be higher than that in the case of a low recording density in order to minimize a delay in the recording time per one recording medium.

When the driving frequency is increased, it goes without saying that the clock frequency for transferring the recording signal to the recording head is increased so as to match the target driving frequency. Furthermore, in order to change the driving frequency, not only the above-described control but also a method of dividing a block or changing an input heat pulse width while using all 64 heaters can be realized. it can.

The above-described embodiment is particularly provided with a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for performing ink ejection even in an ink jet recording system. By using a method in which a change in the state of the ink is caused by energy, it is possible to achieve higher density and higher definition of recording.

The typical structure and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, liquid (ink)
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding the film boiling to an electrothermal transducer arranged corresponding to the sheet or the liquid path in which Since thermal energy is generated in the electrothermal transducer and film boiling occurs on the heat-acting surface of the recording head, bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis can be formed. It is valid. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. 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 the liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angle liquid flow path) as disclosed in the above-mentioned respective specifications, A configuration using U.S. Pat. No. 4,558,333 or U.S. Pat. No. 4,459,600, which discloses a configuration in which a heat acting surface is arranged in a bent region, is also included in the present invention. In addition, for multiple electrothermal transducers,
JP-A-59-123670 which discloses a configuration in which a common slot is used as a discharge part of an electrothermal transducer, and JP-A-59-123670 which discloses a configuration in which an opening for absorbing a pressure wave of thermal energy corresponds to a discharge part. A configuration based on 138461 may be adopted.

Further, 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, the length is determined by a combination of a plurality of recording heads as disclosed in the above specification. This may be either a configuration satisfying the above requirements or a configuration as a single recording head formed integrally.

In addition to the interchangeable chip type that enables electrical connection with the apparatus main body and supply of ink from the apparatus main body described in the above-described embodiment, the ink is integrally formed on the recording head itself. A cartridge type recording head provided with a tank may be used.

It is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like to the configuration of the printing apparatus described above, since the printing operation can be further stabilized. Specific examples thereof include capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof. It is also effective to provide a preliminary ejection mode for performing ejection that is different from printing, in order to perform stable printing.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but may be a single recording head or a combination of a plurality of recording heads. Alternatively, the apparatus may be provided with at least one of full colors by color mixture.

In the above-described embodiment, the description has been made on the assumption that the ink is a liquid. However, even if the ink solidifies at room temperature or lower, it is possible to use an ink that softens or liquefies at room temperature. Or, in the ink jet method, generally, the temperature of the ink itself is controlled 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 that the ink is in a liquid state when the use recording signal is applied.

In addition, in order to positively prevent the temperature rise due to thermal energy as energy for changing the state of the ink from the solid state to the liquid state, the temperature is positively prevented.
Alternatively, in order to prevent evaporation of the ink, an ink which solidifies in a standing state and liquefies by heating may be used. In any case, the application of heat energy causes the ink to be liquefied by application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start to solidify when reaching the recording medium. The present invention is also applicable to a case where an ink having a property of liquefying for the first time is used. In such a case, as described in JP-A-54-56847 or JP-A-60-71260, the ink is held in a liquid state or a solid state in the concave portion or through hole of the porous sheet. It is good also as a form which opposes an electrothermal transducer. 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 to the above, the recording apparatus according to the present invention may be provided not only as an image output terminal of an information processing apparatus such as a computer but also integrally or separately, a copying apparatus combined with a reader, etc. It may take the form of a facsimile machine having functions.

[0055]

As described above, according to the present invention, a plurality of electrothermal transducers provided in a recording head are energized to heat the ink, thereby discharging the ink to perform recording on the recording medium. At the time, the type of externally input print data is determined, and according to the determination result, the internal temperature of the print head and the drive frequency of the print head are adjusted, and the amount of ink discharged from the print head is controlled. On the other hand, there is an effect that good recording quality can be maintained by keeping the ink ejection amount constant.

[0056]

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of a recording apparatus 1 including a recording head that performs recording according to an ink jet method, which is a typical embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a control circuit mounted on a main board 7 of the recording apparatus 1.

FIG. 3 is a schematic diagram illustrating a configuration of a recording head 2.

FIG. 4 is a perspective view showing a detailed configuration of a discharge element 18.

FIG. 5 is a diagram illustrating a relationship between a temperature of a recording head and a discharge amount per ink droplet.

FIG. 6 is a block diagram showing a configuration of a logic circuit of the recording head 2.

FIG. 7 is a flowchart illustrating a temperature control process associated with a printing operation.

FIG. 8 is a diagram illustrating a relationship between a recording density and an arrangement of recording pixels.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording device 2 Recording head 3 Carriage 4 Sub ink tank 5 Ink supply suction tube 6 Flexible print cable (FPC) 7 Main board 8 Suction recovery device 9 Platen 10 Slide shaft 11 Carriage drive belt 12 Head connector 19 Thermistor

Claims (12)

[Claims] 1. A printing apparatus for printing on a printing medium by discharging ink and heating the ink by applying a current to a plurality of electrothermal transducers provided in a printing head, wherein the printing data is externally provided. Input means for inputting the print data, temperature adjustment means for adjusting the internal temperature of the printhead, drive means for driving the printhead, determination means for determining the type of print data input by the input means, The internal temperature of the recording head and the driving frequency of the recording head are adjusted via the temperature adjusting unit and the driving unit according to the result of the determination by the determining unit, and the amount of ink ejected from the recording head is controlled. A recording device, comprising: a control unit. 2. The recording apparatus according to claim 1, wherein the temperature adjusting unit includes a measuring unit that measures an internal temperature of the recording head, and a heating unit that heats the inside of the recording head. . 3. The recording apparatus according to claim 2, wherein said measuring means includes a thermistor. 4. The printing apparatus according to claim 1, wherein the determination unit determines a sparse density of pixels of an image recorded based on the input recording data. 5. The method according to claim 1, wherein the determining unit determines whether to record the input print data at a high resolution or a low resolution according to the density of the pixels. The recording device according to claim 4. 6. The print data recorded at a high resolution includes an image having a large amount of ink ejected per unit area of a print medium, and the print data recorded at a low resolution includes:
6. The recording apparatus according to claim 5, wherein a character image having a small ink ejection amount is included per unit area of the recording medium. 7. When recording the input print data at a high resolution, the control means keeps the internal temperature of the print head relatively low and sets the drive frequency of the print head relatively low. When the input print data is printed at a low resolution, the internal temperature of the print head is kept relatively high, and the drive frequency of the print head is made relatively low. The recording apparatus according to claim 5, wherein the control is performed as follows. 8. The recording apparatus according to claim 1, wherein the driving unit includes a block dividing unit that divides the plurality of electrothermal transducers into a plurality of blocks and drives each block to be energized. apparatus. 9. The recording apparatus according to claim 1, wherein the recording head includes a plurality of ink ejection nozzles that eject ink corresponding to each of the plurality of electrothermal transducers. 10. The ink ejected from the ink ejection nozzle has a surface tension (γ) at an ejection port of the ink ejection nozzle satisfying γ ≦ 40 (dyne / cm). The recording device as described in the above. 11. A discharge angle of the ink discharge nozzle, wherein a contact angle (θ) between the discharge port and the ink is θ ≦ 90.
10. The recording apparatus according to claim 9, wherein the following condition is satisfied. 12. The recording apparatus according to claim 1, wherein the ink ejection amount has a characteristic that increases or decreases in proportion to the ink temperature or the temperature of the recording head.