JP3198213B2 - Ink tank and device to which the ink tank is attached - 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 tank and a recording apparatus using the same.

[0002]

2. Description of the Related Art Recording apparatuses such as printers, copiers, and facsimile machines are configured to record an image formed of a dot pattern on a recording material such as paper or a thin plastic plate based on image information. . The recording apparatus can be classified into an ink jet type, a wire dot type, a thermal type, a laser beam type and the like according to a recording method. Among them, the ink jet method is to perform recording by discharging ink from a recording head to a recording material, and can record a high-definition image at a high speed, and further, because it is a non-impact method, there is little noise, In addition, it has the advantage that it is easy to record a color image using multicolor inks.

A recording head used in the above-described ink jet recording apparatus generally has a liquid path provided with a discharge heater, a common liquid chamber communicating with the liquid path, and an ink for supplying ink to the common liquid chamber. An ink tank containing an absorbing body, an ink supply path connecting the ink tank and the common liquid chamber, and a filter for trapping dust in the ink. In general, an ink having a low surface tension has an advantage of being quickly fixed and hardly bleeding, and can be effectively used in an ink jet recording apparatus, especially a color ink jet recording apparatus. However, ink having a low surface tension tends to degrade character quality, and it is not desirable to use an ink having a low surface tension, particularly for black ink. Therefore, by using ink having a relatively high surface tension as the black ink and using ink having a low surface tension as the other color inks, it has been attempted to improve the quality of black characters and achieve a color image without blurring.

[0004]

However, in the conventional method, (1) the ink having a low surface tension is easily foamed and cut off easily. Air is drawn from the pressure contact part, and the ink supply path, common liquid chamber,
Bubbles accumulate in the liquid path, causing non-foaming, dropping of ink, and the like, and furthermore, the amount of ink used in the ink tank that can be used up is small. (2) Furthermore, in an ink jet recording head that performs recording by dividing a plurality of inks having different surface tensions into a plurality of nozzles, an average diameter of a pipe (hole) of an absorber in an ink tank holding the ink and If the wetting angle with ink is equal, the capillary force differs for each ink, and when all colors are simultaneously sucked, there is a problem that bubbles are taken in from the pressure contact surface between the ink absorber and the filter with low capillary force and improved Was strongly desired.

[0005]

Means for Solving the Problems In order to solve the above problems, the present inventors have made intensive studies and arrived at the present invention. That is, the present invention provides: (1) In an ink tank for storing ink supplied to a print head driven based on a print signal, the ink tank includes a filter in an ink lead-out portion, and is in contact with the filter. A first absorber to be filled, and a second absorber to be filled in contact with the first absorber, and a wetting angle between the first absorber and the second absorber. An ink tank, wherein θ1 and θ2 satisfy cosθ1> cosθ2.

The present invention also provides an ink tank, wherein the first absorber is a porous body, or an ink tank, wherein the first absorber is a fibrous body. It is. Further, the present invention is the ink tank, wherein the second absorber is a porous body.

[0007] The present invention is also an ink tank characterized by being integrally formed with the recording head, and is characterized by being detachably mounted on the recording head. It is a tank.

Further, according to the present invention, a recording head driven based on a recording signal, an ink tank for storing ink to be supplied to the recording head, and ink ejected from the recording head adhere to perform predetermined recording. In an ink jet apparatus comprising a unit for conveying a recording medium and a control unit for controlling the driving of the recording head, the ink tank includes a filter in an ink lead-out unit and is filled in contact with the filter. 1 absorber and a second absorber that is filled in contact with the first absorber, and the wetting angles θ1 and θ2 of the first absorber and the second absorber are cos θ1> cos θ2.

[0009]

【Example】

(1) Description of Recording Apparatus FIG. 4 is a schematic perspective view showing the configuration of an embodiment of the ink jet recording apparatus of the present invention. As shown in FIG. 4, the carriage 2 transmits the forward / reverse rotation of the drive motor 11 to the lead screw 5 through the two drive force transmission gears 9 and 10, so that the carriage 2 moves in the directions indicated by arrows a and b. It is reciprocated. The carriage 2 has an ink jet cartridge 1 in which an ink tank (not shown) for accommodating recording ink and a discharge portion for discharging ink toward the recording paper 30 are integrated, and is opposed to the ink jet cartridge 1. In addition, a platen 4 for conveying the recording paper 30 is rotatably provided. The recording paper 30 conveyed by the platen 4 is pressed by the platen 4 by the paper pressing plate 3 on the side facing the inkjet cartridge 1 and is held so that the interval with the inkjet cartridge 1 becomes a predetermined interval. The recording operation of ejecting ink from the recording head while moving the carriage 2 by the drive motor 11 is performed by the recording control unit 2.
2, the number of recording dots at that time is counted by the dot counting means 25. The recording head of the ink jet cartridge 1 includes:
A temperature sensor 21 is attached to measure the temperature of the recording head, and an electric quantity corresponding to the value is output to the suction operation control means 23. The temperature sensor 21 does not necessarily need to be attached to the recording head, and can be attached to any position of the ink jet recording apparatus as long as the temperature of the recording head can be predicted. Two photocouplers 7 and 8 are provided on the left side in the moving direction of the carriage 2 in the drawing. Each of these photocouplers 7 and 8 is a home position detecting means for confirming the presence of the lever 6 provided at the left end of the carriage 2 in this area and switching the rotation direction of the drive motor 11 and the like. . A cap member 13 supported by a cap support member 14 is provided at a position outside the range of the reciprocating operation in the recording operation of the inkjet cartridge 1 and at which the inkjet cartridge 1 is moved during the suction operation. The cap member 13 is for capping the front surface (discharge port surface) of the recording head portion of the ink jet cartridge 1. In this state, the suction means 12 suctions the inside of the cap member 13, thereby increasing the viscosity of the ink inside the recording head. A head recovery operation such as removal of bubbles is performed. A cleaning blade 15 supported by a blade support member 16 is provided on a side of the cap member 13. The cleaning blade 15 is supported by the blade support member 16 so as to protrude toward the ink jet cartridge 1, and can abut on the front surface of the recording head. As a result, after the suction operation, the cleaning blade 15 is protruded into the movement path of the ink jet cartridge 1 to wipe off dirt and the like on the front surface of the recording head as the ink jet cartridge 1 moves. It goes without saying that the cleaning blade 15 is not limited to this form, and a known cleaning blade can be applied.

(2) Description of Recording Head Here, the recording head of the above-described ink jet recording head will be described with reference to FIG. FIG. 5 is a perspective view of a main part of the recording head of the ink jet cartridge shown in FIG. The recording head is a recording paper 3 as shown in FIG.
0 (see FIG. 4) and discharge port 1 facing at a predetermined interval
a, a plurality of discharge ports 1b are formed at a predetermined pitch, and each liquid path 1 connecting the common liquid chamber 1c and each discharge port 1b.
An electrothermal transducer 1e for generating energy for ink ejection is provided along the wall of d. Common liquid chamber 1
c is connected to the ink tank of the above-described ink cartridge 1 (see FIG. 4), and the common liquid chamber 1c is supplied with ink from the ink tank. The ink supplied from the ink tank to the common liquid chamber 1c and temporarily stored enters the liquid path 1d by capillary action, forms a meniscus at the discharge port 1b, and keeps the liquid path 1d filled. At this time, when the electrothermal transducer 1e is energized through an electrode (not shown) and generates heat, the ink on the electrothermal transducer 1e is rapidly heated, and bubbles are generated in the liquid passage 1d. The ink is ejected from the ejection port 1b by the expansion.

(3) Description of Control Configuration Next, a control configuration for executing recording control of each section of the apparatus configuration will be described with reference to a block diagram shown in FIG. In the figure showing a control circuit, reference numeral 10 denotes an interface for inputting a recording signal, 11 denotes an MPU, and 12 denotes an MPU.
11 storing a control program to be executed by R
OM, 13 is a dynamic RAM for storing various data (the above-mentioned recording signal and recording data supplied to the head), and can also store the number of print dots, the number of ink recording head replacements, and the like. A gate array 14 controls supply of print data to the print head, and also controls data transfer between the interface 10, the MPU 11, and the RAM 13. Reference numeral 20 denotes a carrier motor for transporting the recording head 1, and 19 a transport motor for transporting the recording paper. 15 is a head driver for driving the head,
Reference numerals 16 and 17 denote a transport motor 19 and a carrier motor 20, respectively.
Is a motor driver that drives

FIG. 7 is a circuit diagram showing the details of each part of FIG. The gate array 14 includes a data latch 141, a segment (SEG) shift register 142, a multiplexer (MPX) 143, a common (COM) timing generation circuit 144, and a decoder 145. Recording head 18
Has a diode matrix configuration, and a drive current flows through the ejection heaters (H1 to H128) where the common signal COM and the segment signal SEG match,
Thereby, the ink is heated and discharged.

The decoder 145 decodes the timing generated by the common timing generation circuit 144 and selects one of the common signals COM1 to COM8. The data latch 141 latches the recording data read from the RAM 13 in 8-bit units, and the multiplexer 143 stores the recording data in the segment shift register 1.
In accordance with 42, it is output as segment signals SEG1-8. The output from the multiplexer 143 can be variously changed depending on the contents of the shift register 142, such as 1 bit unit, 2 bit unit, or all 8 bits.

The operation of the above-described control structure will be described. When a recording signal enters the interface 10, the recording signal is converted between the gate array 14 and the MPU 11 into recording data for printing. Then, the motor drivers 16 and 17 are driven, and the recording head is driven according to the recording data sent to the head driver 15 to perform printing.

Embodiment 1 FIG. 1 is a schematic view of an ink jet tank and a recording head showing an embodiment of the present invention. In the present embodiment, two absorbers (absorbers 1 and 2) made of a porous member are provided in the ink tank.
Absorber 2) is filled, and absorber 1 is pressed against the filter surface to prevent gas from being taken in from the pressure contact surface between the filter and absorber 1 during suction, and to further use up the ink in the tank. And Table 1 shows absorber 1
5 shows the structure of the absorber 2 and the physical properties of the ink.

[0016]

[Table 1] Generally, the capillary force of the absorber in the tank holding the ink is determined by the wetting angle θ between the absorber and the ink or the average tube (hole) of the absorber
It changes depending on the diameter r. Capillary force is determined by equation (1). h = 2γCOS θ / (rρg) (1) where h is the capillary force (cm), γ is the surface tension of the ink (dyn / cm), θ is the wetting angle (deg), and r is the radius of the tube (average pore diameter). (Cm), ρ is the density of the ink (g / cm
³ ) and g are gravitational accelerations (cm / s ² ).

The capillary force h ₁ of the absorbent body 1 is greater than the capillary force h ₂ of the absorbent body 2 by increasing the wetting angle with respect to the ink of the absorber 2 from the absorbent body 1 as shown in Table 1. h ₁ = 2 × 31 × cos (5) / (0.016 × 1.0
5 × 980) ≒ 3.64 (cm) h ₂ = 2 × 31 × cos (40) / (0.016 × 1.
05 × 980) ≒ 2.88 (cm) In other words, in the recording head shown in FIG. 1, the ink in the ink tank is more likely to be present in the absorber 1 than in the absorber 2.

In the "suction" suction recovery operation, a large pressure (negative pressure) is instantaneously generated to remove bubbles adhering to the walls of the liquid path, the common liquid chamber, and the supply path from the wall, and to remove a certain amount of air. Aspirate gas and ink. When suction recovery is performed in the recording head shown in FIG. 1, ink in the absorber 1 pressed against the filter fills the supply path, the common liquid chamber, and the liquid path. At this time, the ink is sufficiently filled in the absorber 1, and even if a large negative pressure is generated momentarily, air is not taken in from the pressure contact surface with the filter. In the vicinity of the contact surface between the absorber 1 and the absorber 2, there is no sudden flow of ink, so the ink of the absorber 2 flows gradually by the capillary force of the absorber 1, and returns to the original state after about one minute. Furthermore, absorber 2
A further delay time is required in a region apart from the filter surface, and the ink in the ink tank reaches an equilibrium state in about 10 minutes.

When the ink is ejected from the liquid path at the time of "recording", the ink is gradually consumed in the order from the ink near the filter surface of the absorber 1 to the vicinity of the contact surface with the absorber 2 and the ink in the absorber 2. The difference between the speed at which the ink in the absorber 1 is consumed and the speed of the ink flowing from the absorber 2 to the absorber 1 is proportional to the amount of ink ejected per unit time. That is, when the consumption amount of the ink per unit time increases, the ink does not sufficiently flow from the absorber 2 to the absorber 1, and the ink runs out. When the present invention is performed using a recording head of 128 nozzles and discharging at a discharge amount of 80 (ng) per nozzle, there is no interruption of ink up to 1.024 (g) / (sec), and normal printing is performed. Was completed. This is a range that can be used without any problem in an actual inkjet recording apparatus. That is, by implementing the present invention, gas is not taken in from the pressure contact surface between the filter and the absorber at the time of recovery suction and at the time of recording, and the average pore diameter of the absorber 1 and the absorber 2 are made equal to each other. The amount of ink that can be held in the ink does not decrease because it is not necessary to reduce the average pore diameter of the absorber 1.

Embodiment 2 FIG. 2 is a schematic view of a recording head for explaining the present invention. In this embodiment, a four-color integrated color head capable of recording four colors (yellow, magenta, cyan, and black) is configured such that two types of absorbers (absorber 1 and absorber 2) of each color are filled in an ink tank. The average pore size of the absorber 1 is optimized according to the surface tension and the wetting angle of each color ink. In this embodiment, a porous member is used as the absorber. Table 2 shows the surface tension, ink density, and wetting angle with respect to the absorber of each color ink for explaining the present embodiment.

[0021]

[Table 2] The configuration of the ink supply path for each color ink is the same as that of the four colors, as follows. Assuming that the number of holes and the average hole diameter of all four color absorbers 1 are 40 cores / inch, 0.016 (mm), and the number of holes and the average hole diameter of absorber 2 are 40 cores / inch, 0.021 (mm). Capillary forces h1 (Y), h1 of absorber 1 and absorber 2 of each color
(M), h1 (C), h1 (Bk), h2 (Y), h2
(M), h2 (C) and h2 (Bk) are: h1 (Y) = 2 × 32 × cos (5) / (0.016 ×
1.05 × 980) ≒ 3.87 (cm) h1 (M) = 2 × 35 × cos (5) / (0.016 ×
1.05 × 980) ≒ 4.23 (cm) h1 (C) = 2 × 41 × cos (10) / (0.016
× 1.05 × 980) ≒ 4.90 (cm) h1 (Bk) = 2 × 60 × cos (30) / (0.01
6 × 1.10 × 980) ≒ 6.03 (cm) h2 (Y) = 2 × 32 × cos (5) / (0.021 ×
1.05 × 980) ≒ 3.10 (cm) h2 (M) = 2 × 35 × cos (5) / (0.021 ×
1.05 × 980) ≒ 3.39 (cm) h2 (C) = 2 × 41 × cos (10) / (0.021
× 1.05 × 980) ≒ 3.92 (cm) h2 (Bk) = 2 × 60 × cos (30) / (0.02
1 × 1.10 × 980) ≒ 4.59 (cm).

In the recording head having the above-described structure, the ease of taking in bubbles from the pressure contact surface between the filter of each color and the absorber 1 when the four colors are integrally suctioned from the discharge port is determined by the capillary force of the absorber 1. That is, it becomes difficult to take in bubbles from the pressure contact surface between the absorber 1 of black ink, which has the largest capillary force of the absorber 1, and the filter. This is because the air passage in the absorber 1 decreases as the ink can be held in the absorber 1 in a dense state. Further, the amount of ink (ink gloss) that can be held in the tank of each color depends on the absorber 1
Is smaller than the volume of the absorber 2,
Depends on the average pore size. That is, the larger the average pore diameter of the absorber 2, the more ink can be held. If the capillary force of the absorber 1 is larger than the capillary force of the absorber 2, the ink in the tank will be held by the absorber 1, and the amount of ink used up (ink net) depends on the capillary force of the absorber 1. .

Therefore, in the present embodiment, the average pore diameter r of the absorber 1 is different for each color in order to keep the capillary force of the absorber 1 constant irrespective of the physical properties of the ink. The capillary force of the absorber 1 of each color is changed to the capillary force h1 (Bk) 6.0 of the black absorber 1.
Table 3 shows the average pore size of the absorber 1 of each color when the average particle size was 3 (cm).

[0024]

[Table 3] As a result of performing simultaneous suction of four colors in the recording head having the above configuration, the filter and the absorber 1 were used for all four colors of ink.
No air bubbles were taken in from the pressure contact surface with.

As described above, two absorbers (absorber 1 and absorber 2) are filled in the ink tanks of four colors, respectively, and the average pore diameter of the absorber 1 pressed against the filter is made different for each color. Thereby, even in an ink jet recording head using inks having different surface tension and wetting angle,
It is possible to record stably without taking in air bubbles at the same time when the four colors are simultaneously sucked, to maximize the ink gloss and the ink net, and to reduce the running cost.

Embodiment 3 FIG. 3 shows a schematic view of an ink jet recording head for explaining this embodiment.

In this embodiment, a case will be described in which the present invention is applied to an ink jet recording head constituted by replaceable ink tanks. The inside of the exchange tank is configured to be filled with the absorber 1 and the absorber 2, and the structure of the absorber 1 is the same as that of the first embodiment.
As in the first embodiment, the capillary force of the absorber 2 is larger than that of the first embodiment, and the recording head has a structure in which the average hole diameter of the absorber 1 is different for each color similarly to the second embodiment. In the present embodiment, when the replacement tank is not loaded, the filter surface is exposed at the tip of the supply path.

Normally, when the ink tank is used up and the used up tank is replaced with a full ink tank, bubbles are present in the supply path, the liquid chamber, and the liquid path. When this is suctioned by the suction recovery operation, gas is easily drawn in from the pressure contact surface between the filter and the absorber.

By adapting the present invention to an ink jet recording apparatus of the exchange tank type, the intake of air bubbles is suppressed, and the amount of ink held in the exchange tank is increased by minimizing the volume of the absorber 1. Thus, the ink in the tank can be sufficiently used up. That is, by applying the present invention to a replaceable tank type ink jet recording head, the running cost can be further reduced.

[0030]

As described above, according to the present invention, the ink for suppressing the decrease in the amount of ink that can be held in the absorber and storing the ink to be supplied to the recording head driven based on the exhausted ink recording signal. In the tank
The ink tank is provided with a filter in an ink lead-out portion, and the first ink tank is filled in contact with the filter.
And a second filler filled in contact with the first absorber.
The first absorber and the second absorber.
An ink tank characterized in that the wetting angles θ ₁ and θ ₂ of the absorber satisfy cos θ ₁ > cos θ ₂ . And in an ink tank that stores a plurality of inks respectively supplied to a plurality of recording heads driven based on a recording signal, each of the ink tanks includes a filter in an ink lead-out section, and is in contact with the filter. A first absorber having an average pore size selected according to the surface tension of each ink to be filled, and a first absorber having an average pore size different from the average pore size of the first absorber filled in contact with the first absorber. An ink tank characterized by comprising two absorbers, and a device equipped with these ink tanks, which suppresses a decrease in the amount of ink that can be held by the absorber and maximizes the amount of usable ink. In addition, it is possible to prevent the intake of gas at the time of suction recovery, and to minimize the required suction amount of each color to the minimum necessary. It can provide jet recording head and a recording apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an ink tank and a recording head for explaining a first embodiment of the present invention.

FIG. 2 is a schematic diagram of an ink tank illustrating a second embodiment of the present invention.

FIG. 3 is a schematic view of an ink tank for explaining a third embodiment of the present invention.

FIG. 4 is a schematic perspective view showing the configuration of an embodiment of a recording apparatus for an ink jet cartridge of the present invention.

5 is a perspective view of a main part of the recording apparatus of the ink jet cartridge shown in FIG.

FIG. 6 is a block diagram showing a control configuration of each unit of the apparatus configuration of the embodiment of the recording apparatus of the ink jet cartridge of the present invention.

FIG. 7 is a circuit diagram showing details of each unit in FIG. 6;

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Osamu Iwasaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-5-96742 (JP, A) JP-A-2 -34353 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2/175

Claims (7)

(57) [Claims] 1. An ink tank for storing ink supplied to a print head driven based on a print signal, wherein the ink tank has a filter in an ink lead-out portion and is filled in contact with the filter. First
And a second filler filled in contact with the first absorber.
The first absorber and the second absorber.
Wherein the wetting angles θ1 and θ2 of the absorber satisfy cos θ1> cos θ2. 2. The ink tank according to claim 1, wherein the first absorber is a porous body. 3. The ink tank according to claim 1, wherein the first absorber is a fibrous body. 4. The ink tank according to claim 1, wherein the second absorber is a porous body. 5. The ink tank according to claim 1, wherein the ink tank is formed integrally with the recording head. 6. The ink tank according to claim 1, wherein the ink tank is detachably attached to the recording head. 7. A recording head driven based on a recording signal, an ink tank for storing ink supplied to the recording head, and a recording medium on which ink ejected from the recording head adheres to perform predetermined recording. And a control unit for controlling the driving of the recording head, wherein the ink tank has a filter in the ink lead-out section, and the first ink tank is filled in contact with the filter. An absorber, and a second absorber filled in contact with the first absorber, wherein the wetting angles θ1 and θ2 of the first absorber and the second absorber are cos θ1> The inkjet device according to claim 1, wherein cos θ2 is satisfied.