JPH07137283A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To set an optimum ink temperature to discharge from discharge ports having different opening areas in an ink jet recorder in which a recording head having a plurality of ink discharge ports which have different opening areas is used. CONSTITUTION:Heat insulating heaters 3, 6 and temperature sensors 4, 7 are individually provided in a discharging unit 2 for recording a pale density having a small discharge port 21 which has a relatively small opening area and a discharging unit 5 for recording a dark density having a discharge port 51 which has a relatively small opening area, and ink temperatures are individually controlled at the units by a microprocessor 10.

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 for recording by ejecting ink onto a recording medium such as paper, and more particularly to controlling ink temperature in a recording head.

[0002]

2. Description of the Related Art A recording head used in a conventionally known ink jet recording apparatus generally has a plurality of ejection openings, and the opening areas of the plurality of ejection openings are generally uniform. On the other hand, when controlling the ink temperature of such a recording head, it is often the case that uniform temperature control is performed without individually controlling the temperature of each of the plurality of ejection ports.

By the way, the main purpose of controlling the ink temperature of the recording head is to suppress the variation in the density of the image or the like to be recorded by making the discharge amount of each of the plurality of discharge ports uniform.

[0004]

However, for the purpose of, for example, improving the gradation of the recorded image, a plurality of ejection ports having different ejection port sizes are provided in one recording head to positively eject the ejection amount. It has been proposed to make recordings of different densities possible by making them different. In such a recording head, when the uniform temperature control as described above is performed, the amount of ink movement is relatively large in a portion for performing dark recording, that is, a portion with a large ejection opening area. The ink temperature is lower than the other parts. As a result, a predetermined ejection amount cannot be obtained, and it may not be possible to perform recording with a desired density, particularly in relation to the low density portion.

The present invention has been made in order to solve the above problems, and an object of the present invention is to open an opening area when a recording head having a plurality of ink ejection openings having different opening areas is used. Another object of the present invention is to provide an inkjet recording apparatus capable of optimally controlling the ink temperature for each different ejection port.

[0006]

Therefore, according to the present invention,
In an ink jet recording apparatus that uses a recording head for ejecting ink and ejects ink from the recording head onto a recording medium to perform recording, the recording head has ejection ports whose opening areas are different from each other. A temperature sensor that includes a plurality of ink ejection units, is provided for each of the plurality of ink ejection units, and detects a temperature of ink ejected by the ink ejection unit; and a temperature sensor that is provided for each of the plurality of ink ejection units. A heat-retaining heater for heating the ink ejected from the ejecting portion; and a control circuit for controlling heating of the ink ejecting portion by the heat-retaining heater, based on temperature information from the temperature sensor. To do.

[0007]

According to the above construction, the ink ejecting section having the ejection opening having the relatively small opening area and the ink ejecting section having the ejection opening having the relatively large opening area are respectively configured by different inks. The temperature is controlled. As a result, in the ejection portion having a large opening area, heating control of the heat retention heater can be performed according to the ink temperature drop due to the relatively large ink movement.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of ink temperature control of a recording head in an ink jet recording apparatus according to an embodiment of the present invention.

The above-mentioned ink jet recording apparatus is a publicly known apparatus for recording by ejecting ink onto a recording medium. In the figure, reference numeral 1 indicates a recording head capable of recording dark and light. The recording head 1 includes ejection portions 2 and 5 for performing dark and light recording, respectively. The ejection unit 2 detects a plurality of ejection openings 21 each having a small ejection opening area, an ejection heater 20 provided corresponding to the ejection openings 21, a heat retention heater 3 used for heating ink temperature control ejected from the ejection openings 21, and an ink temperature. The sensor 4 is provided. The discharge unit 5 also has a discharge port 51 having a large discharge port area, a discharge heater 50, a warming heater 6, and a temperature sensor 7.

Reference numerals 8 and 9 denote circuits for supplying electric power to the heat retaining heaters 3 and 6 of the discharge units 2 and 5, respectively, and the microprocessor 10 causes the temperature sensors 4 and 7 to operate.
The power supply by this circuit is controlled based on the temperature information of. The microprocessor 10 also gives an instruction to the ejection heater control circuit 11 to control pulse application to each ejection heater based on the ejection information stored in the recording memory 12.

FIG. 2 is a schematic waveform diagram of pulses applied to each discharge heater. When such a pulse is applied to the ejection heater, the microprocessor 10
Ink temperature control of the dark and light ejection portions 2 and 5 is individually performed based on the information from the temperature sensors 4 and 7. in this case,
With respect to the temperature change during recording, in the ejection portion 2 which performs recording with a light density, the ink movement amount is relatively small, and thus the fluctuation range of the ink temperature is small, and the heater 3 is repeatedly turned on / off correspondingly. As shown in (a). In contrast,
Since more ink moves in the ejection unit 5 that performs recording with a darker density, the heater 6 has a longer on-time and the amount of overshoot also increases, and the change in ink temperature is as shown in FIG. 3B. become.

As described above, in the case where one recording head is provided with the ejection ports having different ejection port areas, the ink temperature control system is provided for each ejection port having a different area. Therefore, it is optimal for each ejection port having a different area. It is possible to control the temperature, and it is possible to record desired densities.

Of the two consecutive pulses of the voltage application pulse shown in FIG. 2, the preceding first pulse contributes to heating the ink in the ejection port to the extent not ejecting the ink, rather than ejecting the ink. There is. Therefore, when the ink temperature is low, the width of the first pulse is increased as shown in FIG. 4A, and when the ink temperature is high, the width of the first pulse is increased as shown in FIG. 4B. The temperature may be shortened and the temperature may be controlled together with the heating of the heat retention heater.

For this control, as shown in FIG. 5, the microprocessor 10 sequentially sets the pulse settings in the discharge heater control units 13 and 14 in accordance with the information from the temperature sensors 7 and 4, respectively. It can be implemented individually.

According to each of the above-described embodiments, in addition to the above-mentioned effects, when a large number of print heads are manufactured, the density variations of the dark print discharge portion and the light print discharge portion which are different for each print head are different for each print head. It is possible to absorb by setting different temperature control temperature.

Further, in the recording mode in which recording is performed by only one of the ejection portions (usually the first and last lines of one page),
Minimal power required for temperature control.

(Others) In particular, the present invention is provided with a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for ejecting ink, particularly in the ink jet recording system. The present invention brings about excellent effects in a recording head and a recording apparatus of the type in which the state of ink is changed by the heat energy. This is because such a system can achieve high density recording and high definition recording.

Regarding the typical structure and principle thereof, see, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740.
What is done using the basic principles disclosed in 796 is preferred. This method is a so-called on-demand type,
It can be applied to any of the continuous type, but especially in the case of the on-demand type, it can be applied to the sheet holding the liquid (ink) or the electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal converter, and film boiling is caused on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal in a one-to-one correspondence
It is effective because bubbles can be formed inside. Due to the growth and contraction of the bubbles, the liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable to make this drive signal into a pulse shape because bubbles can be immediately and appropriately grown and contracted, so that liquid (ink) ejection with excellent responsiveness can be achieved. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the linear liquid passage or the right-angle liquid passage) as disclosed in the above-mentioned respective specifications, US Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
The structure using the specification of No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration corresponding to the ejection portion is disclosed in JP-A-59-138461. That is, according to the present invention, recording can be surely and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium which can be recorded by the recording apparatus. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads or a configuration as one recording head integrally formed.

In addition, even in the case of the serial type as in the above example, the recording head fixed to the apparatus main body or the electrical connection with the apparatus main body and the ink from the apparatus main body by being attached to the apparatus main body The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is integrally provided in the recording head itself is used.

Further, as the constitution of the recording apparatus of the present invention, it is preferable to add an ejection recovery means of the recording head, a preliminary auxiliary means and the like because the effect of the present invention can be further stabilized. Specifically, heating is performed by using a capping unit, a cleaning unit, a pressure or suction unit for the recording head, an electrothermal converter or a heating element other than this, or a combination thereof. Examples thereof include a preliminary heating unit for performing the discharge and a preliminary discharge unit for performing discharge different from the recording.

Regarding the type and number of recording heads to be mounted, for example, only one is provided corresponding to a single color ink, or a plurality of inks having different recording colors and densities are supported. A plurality of pieces may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but it may be either the recording head is integrally formed or a plurality of combinations may be used. The present invention is also extremely effective for an apparatus provided with at least one of full-color recording modes by color mixing.

In addition, in the above-described embodiments of the present invention, the ink is described as a liquid, but an ink that solidifies at room temperature or lower and that softens or liquefies at room temperature may be used. Or, in the inkjet method, it is common to control the temperature of the ink itself within the range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is within the stable ejection range. Sometimes, a liquid ink may be used. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy of the state change of the ink from the solid state to the liquid state, or in order to prevent the evaporation of the ink, it is solidified and heated in the standing state. You may use the ink liquefied by. In any case, by applying thermal energy such as ink that is liquefied by applying thermal energy according to the recording signal and liquid ink is ejected, or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In this case, the ink is
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent No. 1260, it may be configured to face the electrothermal converter in a state of being held as a liquid or a solid in the concave portion or the through hole of the porous sheet. 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, as a form of the ink jet recording apparatus of the present invention, besides 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 be a form or the like.

[0027]

As is apparent from the above description, according to the present invention, the ink ejection portion having the ejection opening having the relatively small opening area and the ink ejection having the ejection opening having the relatively large opening area are provided. The ink temperature of each unit is controlled by a separate structure. As a result, in the ejection portion having a large opening area, heating control of the heat retention heater can be performed according to the ink temperature drop due to the relatively large ink movement.

As a result, it is possible to obtain a desired amount of ink to be ejected at each ejection port, and it is possible to perform recording with an appropriate density.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration for controlling an ink temperature of a recording head according to an embodiment of the present invention.

FIG. 2 is a waveform diagram showing voltage application pulses of the discharge heater shown in FIG.

FIG. 3A and FIG. 3B are diagrams showing changes in ink temperature at each of the ejection portions for dark and light recording under the control of the above embodiment.

4A and 4B are waveform diagrams showing voltage application pulses of an ejection heater according to another embodiment of the present invention.

5 is a block diagram showing a control configuration of another embodiment shown in FIG.

[Explanation of symbols]

 1 Recording head 2,5 Ejection section for performing dark and light recording 3,6 Heat insulation heater 4,7 Temperature sensor 8,9 Electric power supply circuit to heat insulation heater 10 Microprocessor 11,13,14 Discharge heater control circuit 20,50 Discharge Heater 21,51 Discharge port

Claims (2)

[Claims] 1. An inkjet recording apparatus for recording by using a recording head for ejecting ink and ejecting ink from the recording head to a recording medium, wherein the recording heads have different opening areas. A plurality of ink ejection parts having ejection ports, a temperature sensor provided for each of the plurality of ink ejection parts, for detecting the temperature of ink ejected by the ink ejection parts; and for each of the plurality of ink ejection parts A warming heater provided for heating the ink ejected from the ink ejecting section; and a control circuit for controlling heating of the ink ejecting section by the heat retaining heater based on temperature information from the temperature sensor. An inkjet recording apparatus characterized by the above. 2. Each of the plurality of ink ejection units includes an ejection heater that generates thermal energy used for ink ejection, and the control circuit heats the ink by the ejection heater in addition to the heating by the heat retention heater. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is controlled.