JP2006027166A - Image formation device and ink cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the device simplified, less power-consumed and low-priced with a vacuum-adjusting mechanism not needing an electric power source. <P>SOLUTION: The ink in a cartridge 2 installed in a cartridge holder flows into an ink tank 6 which is a storage compartment for feeding the ink through an ink passage 9a. The ink in the ink tank 6 flows into a carriage 1 through an ink passage 9b, and the ink is delivered from a delivery port 5a of an ink head 5 installed in the carriage. If the ink inside the ink tank 6 is consumed, the ink tank 6 on a stand 10 goes up due to the activation of an elastomer (spring 7a) caused by the mass variation (becoming lighter) on the whole ink tank, and then the head difference H is kept constant. Conversely, if the ink is supplemented from the cartridge 2 into the ink tank 6, the ink tank 6 goes down due to the mass variation (becoming heavier) of the whole ink tank 6, and then the head difference H is kept constant. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inkjet image forming apparatus and an ink cartridge.

In an ink jet image forming apparatus, a head of a recording unit (image forming unit) forms and holds a meniscus at a discharge port by the capillary force of the ink so that ink does not leak from the discharge port due to gravity. Therefore, when the meniscus is broken, there is a feature that ink is difficult to leak out if the inside of the discharge port is a negative pressure. Further, in terms of dischargeability, a certain range of negative pressure is required for stable discharge.
Therefore, it is necessary to keep the negative pressure constant. However, the negative pressure has a variation factor that the head is ejected and the ink in the ink tank is consumed, so that the water head is lowered and the negative pressure is increased. .

  To deal with such a problem, Patent Document 1 discloses a technique related to an image forming apparatus using a method of adjusting a negative pressure by moving an ink tank up and down and changing a hydraulic head pressure with the head. According to this, it is possible to obtain normal ink ejection regardless of the characteristics of the ink used.

Patent Document 2 discloses a technique related to an ink jet printer using a capillary force of a porous member. According to this, when the contact portions of the first and second ink absorbers are dried, it is possible to forcibly fill the contact portions with ink and reliably recover from the dry state. is there.
JP 2003-191490 A JP 2003-312001 A

The prior art described above has a configuration in which a flow path for supplying ink to an ink tank or a head is installed in a drive mechanism and driven by a power source such as a motor. Since this configuration is a large configuration, there are the following problems.
(A) The configuration of the apparatus is complicated, and in order to perform electrical control, software, an electric circuit, and electric power for operating them are required.
In recent years, the consumption of energy by electrical equipment is an important issue, and this issue must be solved by reducing the power consumption of the apparatus. In particular, although the ink jet apparatus has been miniaturized, a mechanism for radiating heat generated by the operation of a semiconductor (MPU, memory, etc.) is often insufficient. Therefore, in order to secure a heat dissipation mechanism such as a heat radiating fan, or to prevent heat from being trapped inside the apparatus, it is necessary to design the apparatus larger than necessary.

(B) Further, in the color printer apparatus, since the negative pressure adjusting mechanism is not individually provided for the ink tanks of the respective colors, the print quality is uneven.
In particular, recent color printer apparatuses are required to have high reproducibility with respect to original images. However, if a conventional negative pressure adjusting mechanism (a power source such as a motor for each color ink tank) is provided for each color ink tank, there is a problem that the apparatus becomes large. Therefore, it is necessary to suppress an increase in cost by adopting a mechanism as simple as possible.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an inkjet image forming apparatus that simplifies the apparatus, saves power, and reduces the cost by a negative pressure adjustment mechanism that does not require an electric power source. An object is to provide an ink cartridge.

  In order to solve the above-mentioned problem, the invention according to claim 1 is an inkjet image forming apparatus having an ejection port arranged to eject ink downward, and ejecting ink from the ejection port. And an ink supply storage unit that supplies ink to the ink head, and when the ink liquid level in the ink supply storage unit changes, the ink supply unit It has a negative pressure adjusting mechanism that changes the position of the storage unit and keeps the distance between the ink liquid level and the ejection port constant.

  The invention according to claim 2 is characterized in that the ink supply storage section is an ink tank separated from an ink cartridge.

  According to a third aspect of the present invention, the ink supply storage unit also serves as an ink cartridge.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus for forming an image using a plurality of color inks, wherein the negative pressure adjusting mechanism is provided for each of the plurality of color inks.

  According to a fifth aspect of the present invention, the negative pressure adjusting mechanism is characterized in that an elastic body is provided on an outer wall portion of the ink supply storage portion.

  The invention described in claim 6 is characterized in that an elastic body for adjusting the position is provided on the outer wall portion.

  According to the present invention, as will be apparent from the following description, the negative pressure is kept constant by the negative pressure adjusting mechanism that does not require an electric power source, so that the device can be simplified, power-saving, and low cost. Can be achieved.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a perspective view of an image forming apparatus that forms an image by an ink jet system according to an embodiment of the present invention.
In the ink jet recording apparatus 20, the recording medium 4 (for example, paper) is transported by the transport mechanism 3, and the carriage 1 reciprocates (scans), whereby the ink from the ink head 5 mounted on the carriage is transferred to the recording medium 4. To form an image.

FIG. 2 is a diagram showing an outline of a negative pressure adjusting mechanism in an image forming apparatus that forms an image by an inkjet method.
The ink in the cartridge 2 installed in the cartridge holder (not shown) flows through the ink flow path 9a to the ink tank 6 which is an ink supply storage unit. Further, the ink in the ink tank 6 flows into the carriage 1 via the ink flow path 9b, and ejects ink from the ejection port 5a of the ink head 5 mounted on the carriage.
Here, when the ink in the ink tank 6 is consumed, the ink tank 6 on the table 10 is raised by the urging of the elastic body (spring 7a) due to the mass change (lightening) of the entire ink tank, and the water head difference Keep H constant.
Conversely, when ink is replenished from the cartridge 2 to the ink tank 6, the ink tank 6 is lowered due to the mass change (heavy) of the entire ink tank 6, and the water head difference H is kept constant.

  In FIG. 2, the present invention is applied in a configuration in which the ink tank and the ink cartridge are separated. However, there is an example in which ink is directly supplied to the carriage 1 from the ink storage unit inside the ink cartridge. In this case, an ink cartridge may be placed on the table 10.

In the case of a color image forming apparatus, the negative pressure adjusting mechanism described above can also be applied to each color ink tank.
(1) When the degree of ink consumption of each color is the same, one negative pressure adjustment mechanism is sufficient.
On the other hand, when the degree of consumption of each color ink is different,
(2) For example, when black ink and other color inks are different, a negative pressure adjusting mechanism for black ink and a negative pressure adjusting mechanism for other colors may be provided.
(3) For example, when the ink consumption levels of all colors are different, a negative pressure adjustment mechanism may be provided for each color.

FIG. 3 is a diagram showing the relationship between the ink consumption of the ink tank and the negative pressure in the image forming apparatus that performs image formation by the ink jet method.
The solid line in the figure shows the relationship between the negative pressure of the ink tank and the ink consumption, and is called a “pressure fluctuation curve” accompanying the ink consumption.
The “dischargeable range” in FIG. 3 will be described.
In FIG. 2, an upward force (negative pressure) against the gravity is applied to the ink droplets so that the ink droplets in the vicinity of the ejection port 5 do not cause ink leakage due to the gravity acting on the ink droplets. Need to work. The lower limit of the negative pressure value (the lower limit of the absolute value) depends on the mass density of the ink, the size of the ejection port 5, and the like, but is generally about -10 to -20 mmAq.
Also, if the negative pressure is too large with respect to the gravity of the ink water droplets, ink cannot be ejected. The upper limit (the upper limit of the absolute value) depends on the mass density of the ink, the size of the ejection port 5 and the like, as in the case of the lower limit, but is generally about −110 to −120 mmAq.
That is, ink can be ejected when the negative pressure is within the lower and upper limits shown in FIG.

Next, the “pressure fluctuation curve” in FIG. 3 will be described.
(1) The left part of the pressure fluctuation curve
When ink is consumed in a state where there is sufficient ink in the ink tank 6, the water surface of the ink tank 6 falls and the water head difference H increases. The relationship between the water head difference H and the negative pressure is proportional. At this stage, since the amount of ink contained in the ink tank is sufficiently large, the spring 7 which is an elastic body is in a contracted state until a certain amount of ink is consumed (until a predetermined negative pressure is reached). .

(2) Central part of the pressure fluctuation curve (flat part: constant head differential range)
When the ink in the ink tank 6 is consumed to some extent and the entire ink tank 6 becomes light, it is biased by the restoring force of the elastic body (spring 7a), that is, the ink tank 6 moves upward, but the ink tank 6 By using an elastic body in which the overall gravity and the restoring force of the elastic body are balanced, a change in negative pressure accompanying an increase in ink consumption is prevented.
In this embodiment, the negative pressure is set to a value within the dischargeable range (for example, −100 mmAq).
Further, in actual operation, it is preferable to operate within a fixed head differential range (within a constant negative pressure range) shown in FIG. 3, and also in this embodiment, the internal pressure of the ink tank 6 is always constant so that the negative pressure is constant. The ink amount is adjusted.

(3) The right part of the pressure fluctuation curve
Further, when the ink in the ink tank 6 is consumed, the spring 7 is completely restored from the contracted state (becomes a natural length state) or by a stopper that restricts the bias of the spring 7. The ink tank 6 does not move upward, and only the water head difference H increases. That is, the negative pressure increases.

  The embodiment described above is an example of a preferred embodiment of the present invention. However, the embodiments of the present invention are not limited to these, and various modifications can be made without departing from the gist of the present invention. In the following, a modified embodiment is shown.

(Modification)
A modified embodiment of the present invention will be described with reference to FIG.
In the same manner as shown in FIG. 2, the ink in the cartridge 2 flows through the ink flow path 9a to the ink tank 6 which is an ink supply storage unit. Further, the ink in the ink tank 6 flows into the carriage 1 via the ink flow path 9b, and ejects ink from the ejection port 5a of the ink head 5 mounted on the carriage.
Here, when the ink in the ink tank 6 is consumed, the ink is biased by the elastic body (resin plate spring 7b) provided on the outer wall portion of the ink tank 6 due to the mass change (lightening) of the entire ink tank. The entire tank 6 is raised and the head difference H is kept constant.
Conversely, when ink is replenished from the cartridge 2 to the ink tank 6, the ink tank 6 is lowered by the mass change (heavy) of the entire ink tank 6, and the water head difference H is kept constant.

  Further, the elastic body (resin plate spring 7b) may be provided not only on the outer wall portion of the ink tank 6 as in the modified example, but also on the outer wall portion of an ink cartridge including an ink supply storage portion.

1 is a perspective view of an image forming apparatus that performs inkjet image formation according to an embodiment of the present invention. FIG. 3 is a diagram illustrating an outline of a negative pressure adjusting mechanism in the image forming apparatus. FIG. 4 is a diagram illustrating a relationship between an ink consumption amount of an ink tank and a negative pressure in the image forming apparatus. It is the figure which showed the outline of the negative pressure adjustment mechanism in an image forming apparatus (modification example).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carriage 2 Ink cartridge 3 Conveyance mechanism 4 Recording medium (paper etc.)
DESCRIPTION OF SYMBOLS 5 Ink head 5a Ejection port 6 Ink tank 7a Spring 7b Resin leaf spring 8 Cap 9a, 9b Ink flow path 10 units 20 Inkjet recording device

Claims (6)

An image forming apparatus using inkjet,
An ink head having a discharge port arranged to discharge ink in a downward direction and discharging ink from the discharge port;
An ink supply storage for supplying ink to the ink head,
When the ink liquid level in the ink supply storage unit changes, the position of the ink supply storage unit is changed by the urging of the elastic body, and the distance between the ink liquid level and the discharge port is kept constant. An image forming apparatus having a pressure adjusting mechanism.   The image forming apparatus according to claim 1, wherein the ink supply storage unit is an ink tank separated from an ink cartridge.   The image forming apparatus according to claim 1, wherein the ink supply storage unit also serves as an ink cartridge. An image forming apparatus that forms an image using a plurality of colors of ink,
The image forming apparatus according to claim 1, wherein the negative pressure adjusting mechanism is provided for each of the plurality of colors of ink.   The image forming apparatus according to claim 1, wherein the negative pressure adjusting mechanism is provided with an elastic body on an outer wall portion of the ink supply storage unit.   An ink cartridge comprising an elastic body for adjusting a position on an outer wall portion.

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