JPH06134989A - Ink-jet recorder - Google Patents

Abstract

PURPOSE:To make the density of characters and pictures clear by providing a plurality of heaters and a common heater, which is heated together with the above described heaters, in liquid paths, which constitute a recording head and send ink, controlling these heaters, and finely changing the sizes of the discharged droplets through ink-jet ports. CONSTITUTION:A plurality of the pairs of bubble-generating heaters 43 and 43A for jetting ink through a plurality of ink-jet ports 41 are provided on the upper surface of a substrate 42. Power supply patterns 44 are connected and provided for operating the bubble generating heaters 43 and 43A. Liquid paths 451 which are connected to the ink-jet ports 61 are formed by bonding a cover 45 to the upper surface of the substrate 42. Namely, a plurality of longitudinal grooves 46 are formed at the same specified interval as a plurality of the electrode patterns 44 at the bonding surface of the cover 45. When the cover 45 is bonded to the substrate 42, the electrode patterns 44 and the bubble generating heaters 43 and 43A are arranged in correspondence with the insides of the liquid paths 451 formed by a plurality of the longitudinal grooves 46. Here, the diameter of a droplet 4E is changed by the control with the heater 43.

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 on a recorded matter by ejecting ink droplets from a recording head, and in particular, a plurality of heating elements for ejecting ink are provided in the recording head to form bubbles. The present invention relates to an inkjet recording device that controls ink droplets that are generated.

[0002]

2. Description of the Related Art In a conventional bubble-jet type ink jet recording apparatus, one ejection heater is provided in a liquid passage provided for ejecting ink droplets, and the ejection heater is heated to Bubbles are generated in the liquid passage, and the ink droplets are ejected from the ink droplet ejection port. The ink jet disclosed in Japanese Patent Laid-Open No. 3-10843 controls the gradation of an image by changing the heat generation amount of the one discharge heater to change the discharge amount of ink droplets.

[0003]

However, in the bubble jet method as described above, the amount of heat generated by the heating element provided in the ink liquid passage is changed to change the amount of ink discharged, thereby discharging an ink droplet to form an image. Although the gradation reproducibility was changed, the generation position of the valve provided inside the ink discharge port was fixed, and the generation position of the valve (hereinafter referred to as bubble) did not change, so the ink discharge amount changed substantially. Without doing so, on the contrary, the change in the ejection speed of ink drops becomes large,
When ink droplets are ejected on the recording paper to form an image,
There is a problem that a good image cannot be provided due to ink droplets in which gradation reproducibility of recorded characters or images on recording paper becomes unstable.

[0004]

According to the present invention, in order to solve the above problems, the present invention according to claim 1 has a recording head provided with an ink ejection port, and the ink is ejected from the ejection port. In an ink jet recording apparatus for performing recording on a recording medium by ejecting the ink by a thermal means, the recording head provided with the ink ejection port and having a liquid path connected to the ejection port, A plurality of heating elements for ejecting ink are provided in the liquid passage in the direction of the ejection port.

According to a second aspect of the present invention, the plurality of ink ejection heating elements are selectively heated to eject ink from the ejection ports.

According to a third aspect of the present invention, the ink is ejected from the ejection ports by changing the heat generation timing of the plurality of ink ejection heating elements.

According to a fourth aspect of the present invention, in each of the plurality of ink discharge heat generating portions, one discharge heat generating element or ink discharge heat generating elements adjacent to each other are simultaneously heated to discharge ink from the discharge ports. I am trying.

According to a fifth aspect of the present invention, there is provided an ink jet recording apparatus which has a recording head provided with an ink ejection port, and performs recording on a recording medium by ejecting ink from the ejection port by a thermal means. In the above-described recording head, the recording head is provided with the ink ejection openings, and the liquid passages are respectively connected to the ejection openings, and a plurality of ink ejection heads are provided in the plurality of liquid passages toward the ejection openings. It is characterized in that a heating element and a heating element arranged in parallel with the plurality of ink discharging heating elements are provided.

According to a sixth aspect of the present invention, the plurality of ink discharging heating elements and the one heating element are laminated in the liquid passage.

The invention according to claim 7 is achieved by an ink jet recording apparatus, characterized in that the plurality of ink discharging heating elements and the one heating element are provided in the liquid path so as to be separated from each other. .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings shown as embodiments will be described below.

FIG. 1 shows an ink jet recording apparatus 10 according to the present invention.
The overall structure of 0 is shown.

Reference numeral 1 denotes a feed roller for the recording paper 2, which is a pinch roller 1a provided on the lower side of the feed roller 1 so as to be separable from the feed roller 1, and the recording paper 2 is sandwiched between the feed rollers 1 and fed in the direction of arrow A. It is configured to be sent and discharged in the B direction. When the recording paper 2 is discharged in the B direction, it is discharged between the platen 3 and the inkjet head 4 (hereinafter referred to as the recording head 4).
The recording head 4 is provided on a carriage 6 slidably provided on a guide rod 5 so that the recording paper 2 discharged onto the platen 3 can be printed. Each end of the wire 8 concerned with the pulleys 7 and 7a is fixed to the carriage 6 so as to reciprocate the recording head 4 in the left-right direction indicated by the arrow C, and the drive pulley 9 driven by the stepping motor M is connected to the drive pulley 9. A part of the wire 8 is wound, and the carriage 6 is reciprocated left and right via the wire 8 by the drive pulley 9 driven by the stepping motor M, and the recording head 4 reciprocates between the print widths P. Print on recording paper 2. The feed roller 1 and the pinch roller 1a are rotatably provided in a part of the ink jet recording apparatus 100.
Is provided with a rotation means (not shown) that rotates automatically or manually.

A home position HP of the carriage 6 is provided at a position outside the print width P, and a recovery device 7 that can move in the direction of the arrow D so as to closely contact and separate from the front surface of the recording head 4 is provided at the home position HP. It is provided. A cap 8 for sealing the ink ejection port 41 of the recording head 4 is provided on the front surface of the recovery device 7, and when the ink ejection port 41 is covered with the cap 8, the recovery device 7 has an inside of the cap 8 and an atmosphere. An air valve 9 is provided so as to communicate with the.

As a problem peculiar to the ink jet recording apparatus, clogging of the ink ejection port 41 due to foreign matter (paper dust or other fine dust) or non-ejection of ink from the ink ejection port 41 due to drying of the recording head 4 is caused. There is a problem such as
By covering 41, the occurrence of the above-mentioned problem is prevented. The recovery device 7 is provided as such means.

FIG. 2 is an exploded perspective view showing an embodiment of the recording head 4 shown in FIG. In this embodiment, the substrate
A plurality of bubble generating heaters 43, 43A for ejecting ink from the plurality of ink ejection ports 41 are provided on the upper surface of 42 as a set, and electrode patterns 44 for operating the bubble generating heaters 43, 43A are provided respectively. Connect and provide. By joining a cover 45 to the upper surface of the substrate 42, a liquid path 45 communicating with each ink ejection port 41 is formed. Ie cover
A plurality of vertical grooves 46 are formed on the joint surface of 45 at the same predetermined intervals as the plurality of electrode patterns 44, and are formed by the plurality of vertical grooves 46 when the cover 45 is bonded to the substrate 42. The electrode pattern 44 and the bubble generating heaters 43 and 43A are arranged correspondingly in the liquid passage 451.

A cover 45 is bonded to the substrate 42 so that each liquid path 45 is formed.
After forming 1, the ejection port forming member 47 in which the ink ejection port 41 is formed is joined in the arrow direction as shown in the figure. As described above, the ink discharge port 41 and the liquid passage 451 formed by the vertical groove 46 are formed. Also, the second half of the substrate 42 and the cover 4
A common liquid chamber, which is connected to each liquid passage 451 in common, is formed between the latter half and the latter half by joining them. Further, an ink supply port 48 communicating with the common liquid chamber is provided outside the latter half of the cover 45.

FIG. 3 is a schematic diagram for explaining the basic principle of ink ejection of the recording head 4 according to FIG.

In FIG. 3, only one bubble generating heater 43 shown in FIG. 2 is shown.

First, in (A), the bubble generating heater 43 is used.
The stage before driving (hereinafter referred to as the heater) is shown.
The inside of 451 is filled only with the liquid of the ink 4A. When the heater 43 is energized in this state, the ink 4A in the area in contact with the heater 43 is rapidly heated, and then a plurality of small bubbles 4B are generated, as shown in FIG. Then, as shown in (C), it becomes one bubble 4C,
When the bubble 4C expands greatly as shown in (D), the liquid path
The pressure in 451 rises, and the ink 4A is pushed out from the ink ejection port 41. Ink 4A pushed out is (E)
As shown in, the droplets 4E are discharged.
After this, the bubble 4D becomes smaller due to the pressure in the liquid passage.

Next, as shown in (F), the ink droplet 4E
Is completely discharged, the bubbles 4D in the liquid passage 451 also disappear completely, and the ink 4A is supplied into the liquid passage from the rear. In this way, the droplets 4E made of ink are discharged onto the recording paper to perform printing.

As described above, the ink jet recording apparatus 100
In FIG. 3, basically, as shown in FIG. 3, since the volume of bubbles generated by the heater 43 in each liquid passage 451 is discharged as a droplet 4E, the size of the droplet 4E is controlled by controlling the heater 43 ( The diameter can be changed.

FIGS. 4A, 4B and 4C show an embodiment of the recording head 4 of the present invention. FIG. 4A shows the heater 43, as shown in the exploded perspective view of FIG. 43A is provided in the liquid passage 451, and a power source (described later) is turned on for the heaters 43 and 43A, respectively.
Connect switches S ₁ and S ₂ that turn OFF. Now switch S ₁
When turned on, the heater 43 is heated to form the bubbles 4C in the bubble generation order shown in FIG.
The ink 4A in 1 is ejected from the ink ejection port 41 as a droplet 4E. At that time, the size of the droplet 4E is determined by the positions of the heaters 43 and 43A provided in the liquid passage 451.

That is, since the position of the heater 43 is provided in the vicinity of the ink ejection port 41, the droplet 4E ejects only the ink 4A between the heater 43 and the ink ejection port 41. Therefore, the droplet 4E is ejected as a small droplet 4E as shown. Following FIG. 4 (b) switch S ₂ to the heater 43A
Is turned on and the switch of the heater 43 is turned off, so that bubbles 4C are generated in the ink 4A in the heater 43A portion by the same action as described above. In this case, between the heater 43A and the ink ejection port 41, more ink 4A than that shown in FIG. 4A is filled, and the size of the bubble 4C is the same.
The ink is accelerated by the pressing force of A and the entire amount of the ink 4A in the liquid passage 451 is ejected from the ink ejection port 41 as a droplet 4E. Therefore, the ejected droplet 4E becomes large. Further, in order to sufficiently increase the ejection force of the droplet 4E, it is effective to turn on the switch S ₁ at a constant timing after turning on the switch S ₂ so that the bubble 4C further grows.

Next, in FIG. 4C, when the switches S ₁ and S ₂ are simultaneously turned on for the heaters 43 and 43A provided in the liquid passage 451,
Since the heaters 43 and 43A are simultaneously heated, the bubble 4C is formed between the heater 43 and the heater 43A. In this case, the position of the bubble 4C is generated in the middle of the bubble generating position shown in FIGS. Therefore, the amount of ink in the liquid path 451 also becomes an intermediate amount of ink, and the droplet 4E corresponding to the intermediate amount is formed and ejected from the ink ejection port 41. 2 as above
By appropriately turning on and off the power supply switches S ₁ and S 2 of the individual heaters 43 and 43A, three types of drops 4E are formed,
The gradation of the image, that is, the density can be finely adjusted. Furthermore, FIG.
As shown in (d) and (e), heaters 43B, 43C, and 43D are provided at regular intervals on the substrate 42 in the liquid passage, and one cover 45 is provided.
The heaters 43B, 43C, 43D and the heaters 43E, 43F, 43G are provided in a zigzag pattern on the side as shown in FIG. 4 (e), and the heaters 43B, 43C, 43D have switches S ₃ , respectively.
S _4, connects the S _5, the heater 43E, 43F, to 43G connects each switch _{S 6, S 7, S 8} , the switches appropriately O
By turning N and OFF, bubbles 4C are formed at positions in the liquid passage from the upper and lower sides. In this way, by providing a large number of heaters in a zigzag pattern at the upper and lower positions, the position of the bubble 4C is changed more minutely, and the size of the droplet 4E can be adjusted, so that the density can be finely adjusted.

5 (a) (b) (c) (d), a common heater 436 is provided on the substrate 42 in the liquid passage and switches S ₆ , S ₇ , S ₈ ,
A large number of heaters 431, 432, 433, to which S ₉ and S ₁₀ are respectively connected,
434 and 435 are arranged on the common heater 436 at regular intervals. Further, the switch S ₁₁ is connected to the common heater 436. In the recording head 4 of this embodiment, as shown in the temperature distribution diagram of FIG. 7A, first, the switch S _{6 of the} heater 431 is turned on to generate the bubbles 4C in the liquid passage 451 and the temperature of the heater 431 portion is changed. Let α be the distribution, and then switch S _{11 of the} common heater 436.
Is turned on to raise the temperature T in the liquid passage 451 together with the heater 431 to set the temperature distribution to β, and in that state, the heater 431 and the common heater 436 further heat the liquid 4A in the liquid passage 451 to raise the liquid temperature. Then, as shown in FIG. 7A, the temperature Tc is set to the heater 431.
When the high temperature range of the part passes, the bubbles 4C are rapidly generated in the liquid passage 451. The common heater 436 and the heater 431
Thus, the bubbles 4C can be formed in a short time, and the density adjustment by the ink becomes better.

FIG. 5B shows another modification using the common heater 436 shown in FIG. 5A. In this embodiment, a common heater 436 connected to the switch S ₁₁ is provided in the liquid path on the substrate 42, while a large number of heaters 431 and 432 are connected to the switches S ₆ , S ₇ , S ₈ , S ₉ , and S ₁₀ , respectively. , 433, 434, 435 are provided on the cover 45 in the liquid passage at regular intervals.

In FIG. 5C, the common heater 436 shown in FIG. 5A is removed and the switches S ₆ , S ₇ , S ₈ , S ₉ , and S ₁₀ are removed.
Multiple heaters 431, 432, 433, 434, 435 each connected to
When the air bubbles 4C are formed by the heater 432 part, for example, only the switches S ₇ are turned on when the only ones are provided on the substrate 42 in the liquid passage 451 at regular intervals.
Switch S _6, S ₈ as after, also heated by delaying the timing relative to the other heater 431,433,434,435,
ON the S _9, S _10, so as to larger bubbles 4C generated by the heater 432 parts.

Next, the present embodiment shown in FIG. 5D is the same as that shown in FIG.
In (a), the switches S ₈ and S ₉ are turned on to turn on the heaters 433 and 4
Heat 34. A temperature distribution chart of the heater of this embodiment is shown in FIG. First, simultaneous heating of the heaters 433 and 434 causes a temperature distribution of two peaks indicated by a temperature distribution of α ₁ , and then the switch S ₁₁ of the common heater 436 is turned on, whereby the heaters 433 and 434 and the common heater 436 are connected to each other. A temperature distribution β ₁ heated at is generated. The means for simultaneously heating the heaters 433 and 434 to generate the bubble 4C is basically the same as the operation shown in the embodiment of FIG.

By continuing the heating in the above order, the temperature distribution of FIG. 7B rises above the temperature Tc while the temperature distribution of the two peaks is set higher, and the heaters 433 and 434 are heated as shown. Bubbles 4C are rapidly formed at the portion, and the droplet 4E is ejected from the ink ejection port 41 to form an image.

FIGS. 6A and 6B show a common heater 436 to which the switch S ₁₁ is connected, switches S ₆ , S ₇ , S ₈ and
All of the heaters 431, 432, 433, 434, and 435 connected to S ₉ and S ₁₀ are provided on the substrate 42 in the liquid path. As shown in FIG. With the heaters 431, 43
2,433,434,435 are installed side by side. With this structure, the bubbles 4C can be rapidly formed at a plurality of positions in the liquid passage 451 as described above, and thus fine image density adjustment is possible.

The heat generation timing of the common heater 436 used in FIGS. 5 and 6 is not limited to the same as that of each heater, and it is also preferable to preheat. By doing this,
The viscosity of the ink 4A in the recording head 4 can be kept stable and stable printing can be performed.

FIG. 8 shows an embodiment showing a control means for discharging the ink 4A of the recording head 4 from the liquid passage 451 as a droplet 4E. This is a case where data is input and output from the input device 6 according to a command from the control unit 11.

First, the CPU 5 selects 8-bit density data for image formation through the input device 6 from the density data storage unit 7 as 3-bit density data converted from the ROM 10 for gradation correction for recording and selects each element. It is sent to the heat generation driver 8 to generate heat.

The heat generation driver 8 corrects the heat generation amount of each element according to the information sent from the ROM 9 which stores the correction data of each heat element, while the density data causes the switches S ₁ , S ₂ , S ₃ , S ₄ ... • the S ₁₁ ON, to OFF operated,
Indicated common heater 436 and heaters 431 and 43 for ink control
2,433,434 are selectively or simultaneously heated and controlled to eject the droplets 4E formed by the ink 4A in the direction of the arrow as described above, thereby forming characters or images on the recording paper 2 or the recording object. Form.

The ROM 9 is for correcting the non-uniform heat generation amount of each element by performing pulse width modulation on the applied current time.

On the other hand, in the case of recording on the recording paper 2, the ink jet recording apparatus 100 shown in FIG. 1 is controlled by the CPU 5 via the input device 10 to control the recording head 4 and the feed roller 1 to accurately drop a character or an image. It is formed by 4E.

[0038]

As described above, a plurality of heaters and a common heater which is heated together with the plurality of heaters are provided in the liquid path for feeding the ink which constitutes the recording head 4 of the present invention, and the plurality of heaters and the common heater are controlled. By doing so, it is possible to finely change the size of the droplet ejected from the ink ejection port, and particularly to clearly record characters and image density.

[Brief description of drawings]

FIG. 1 is a perspective view showing an internal configuration of an inkjet recording apparatus using a recording head of the present invention.

FIG. 2 is an exploded perspective view showing an internal configuration of the recording head unit.

FIG. 3 is an explanatory diagram showing a principle of ink ejection of an inkjet according to the present invention.

FIG. 4 is a cross-sectional view showing the action of the ink ejection means of the present invention.

FIG. 5 is a cross-sectional view showing another embodiment of the ink ejection means of the present invention.

FIG. 6 is a cross-sectional view showing another embodiment of the ink ejection means of the present invention.

FIG. 7 is an explanatory diagram showing a temperature distribution of a heater temperature of the ink discharging means of the present invention.

FIG. 8 is a block diagram showing control of ink ejection means of the present invention.

[Explanation of symbols]

1 Feed Roller 2 Recording Paper 4 Recording Head 41 Ink Discharge Port 42 Substrate 43, 43A, 43B, 43C, 43E, 43F, 43G Heater 45 Cover 451 Liquid Path 4A Ink 4E Droplet S ₁ , S ₂ , S ₃ , S ₄ , S ₅ , S ₆ , S ₇ , S ₈ switch 5 CPU 7 Density data storage 6 Input device 100 Inkjet recording device

Claims (7)

[Claims] 1. An ink jet recording apparatus, comprising: a recording head provided with an ink ejection port; wherein ink is ejected from the ejection port by a thermal means to perform recording on a recording medium. Is provided with a discharge port of
An ink jet recording apparatus comprising: the recording head having a liquid path connected to the ejection port; and a plurality of ink ejection heating elements provided in the liquid channel toward the ejection port. 2. The ink jet recording apparatus according to claim 1, wherein the plurality of ink ejection heating elements are selectively heated to eject ink from the ejection ports. 3. The ink jet recording apparatus according to claim 1, wherein the heat generation timings of the plurality of ink ejection heating elements are different from each other to eject ink from the ejection ports. 4. The ink jetting head is characterized in that, in the plurality of ink jetting heating sections, one jetting heating element or ink jetting heating elements adjacent to each other are simultaneously heated to eject ink from the jetting port. 1. The inkjet recording device according to 1. 5. An ink jet recording apparatus, comprising: a recording head provided with an ink ejection port; wherein ink is ejected from the ejection port by a thermal means to perform recording on a recording medium. Is provided with a discharge port of
Further, the recording head is provided with a liquid path connected to each of the ejection ports, a plurality of ink ejection heating elements in the plurality of liquid channels toward the ejection port, and a plurality of ink ejection heat generations. An ink jet recording apparatus comprising a body and a heating element arranged in parallel. 6. The ink jet recording apparatus according to claim 5, wherein the plurality of heating elements for ejecting ink and the one heating element are laminated on each other and provided in the liquid passage. 7. The ink jet recording apparatus according to claim 5, wherein the plurality of ink discharging heat generating elements and the one heat generating element are provided in the liquid path so as to be separated from each other.