KR100426091B1 - Ink cartridge for printer - Google Patents

Abstract

Disclosed is an ink cartridge for a printer that can adjust an internal pressure of an ink reservoir according to an ink capacity contained therein. The ink cartridge for a printer according to the present invention, which is installed inside a housing and which can be shrunk and expanded, forms a negative pressure inside the ink storage container with respect to the outside of the ink storage container, and maintains the size within a predetermined range. And a pressure regulating device to make it. In addition, the ink storage container is formed in a conical shape in which one side is coupled to the inner wall of the housing and the upper end thereof has a larger cross-sectional area than the lower end thereof. In addition, the ink cartridge is provided with a pressure adjusting device including an elastic body, a mass body, and the like coupled to the side of the ink storage container, so that the weight of the ink contained in the ink storage container and the mass of the mass body or the elastic force of the elastic body may be used. The outer wall is pressed in the direction of expansion. According to this, since the negative pressure is formed in the ink storage container and the negative pressure can be maintained within the available range in which the ink can be sprayed, the ink that is not supplied to the nozzle portion and discarded while remaining in the ink storage container can be used. As a result, the maintenance cost of the printing press is reduced.

Description

Ink cartridges for printers {Ink cartridge for printer}

The present invention relates to an ink cartridge for a printer, and more particularly, to an ink cartridge for a printer that can adjust the pressure formed inside the ink storage container according to the capacity of the ink stored therein.

Ink cartridges are typically used in printers that print using ink jetting, such as the layout of printers, plotters, and circuit masks that require precise pattern distribution of the ink contained therein.

FIG. 1 schematically shows the structure of a conventional ink cartridge 10 used in an inkjet printer. According to the drawings, the ink cartridge 10 includes a housing 11, an ink reservoir 15, and a pressure. The adjusting device 20 is provided.

The housing 11 has a space portion formed therein by coupling the plurality of side walls 13 and the casing 12. In addition, the ink storage container 15 is partitioned by the thin film 16 and the frame 17 installed in a state where the space is coupled to each other to accommodate the ink. The thin film 16 is typically formed of a flexible material capable of shrinking and expanding.

The ink cartridge 10 configured as described above is formed inside the housing 11 inside the ink storage container 15 so that ink is ejected in the form of droplets from the nozzle unit (not shown) and ink does not continue to leak after the ink is ejected. Pressures of magnitude less than atmospheric pressure, ie negative pressure, must be formed. Accordingly, the pressure regulating device 20 includes a plurality of plates 21 for pushing the thin film 16 outward and a spring 22 disposed between the plates 21 in the ink storage container 15. Is installed and its operation is as follows.

When ink is supplied to the nozzle unit after the ink is injected through the nozzle unit, the ink reservoir 15 is contracted. After the required ink is supplied to the nozzle unit, the ink storage container 20 is expanded again by the plate 21 expanding the thin film 16 to the outside by the elastic force of the spring 22. A negative pressure is formed inside the 20.

However, if the printing operation is continuously performed using the conventional ink cartridge 10, the ink reservoir 15 is kept constant while only by the elastic force of the spring 22, while the ink reservoir ( 15) The amount of ink remaining inside continues to decrease.

Accordingly, as shown in FIG. 2, a negative pressure greater than the magnitude of the negative pressure required for ink ejection is formed in the ink storage container 15 at some point while the ink is continuously consumed. As the negative pressure increases, the ink inside the ink reservoir 15 may not be supplied to the nozzle unit.

Therefore, the conventional ink cartridge 10 has a maintenance cost of a product such as having to replace the ink cartridge 10 in a state in which the ink remaining in the ink storage container has not been consumed or replenish the ink in the ink storage container. There is a problem of lifting excessively.

The present invention has been made to solve the above-mentioned conventional problems, the ink cartridge for a printer having an improved structure in order to keep the size of the negative pressure formed inside the ink storage container in a stable range within the ink injection possible The purpose is to provide.

1 is an exploded perspective view schematically showing the configuration of a conventional ink cartridge.

FIG. 2 is a graph schematically illustrating a change in magnitude of a negative pressure formed inside the ink reservoir of FIG. 1. FIG.

Figure 3 is an exploded perspective view showing the structure of the ink cartridge according to the embodiment of the present invention.

4A to 4B are partial cutaway side cross-sectional views showing the ink cartridge with the ink contained in the ink reservoir of FIG. 3;

5 is an exploded perspective view showing the structure of an ink cartridge according to another embodiment of the present invention.

6A to 6B are partial cutaway side cross-sectional views showing the ink cartridge with the ink contained in the ink reservoir of FIG. 5;

Figure 7 is a side cross-sectional view schematically showing the structure of an ink cartridge according to another embodiment of the present invention.

8 is a graph showing the negative pressure change inside the ink reservoir when using the pressure regulator of FIG.

Explanation of symbols on the main parts of the drawings

30, 50, 50 ': ink cartridge 31, 51: housing

35, 55: ink reservoir 36, 56: ink outlet

37, 57: outer wall 40, 60: pressure regulator

41: support member 41a: fixing protrusion

43, 65: mass 60: leaf spring

61: fixing member 62: connecting portion

63: movable member

The ink cartridge for a printer according to the present invention for achieving the above object is, the ink storage container of the flexible material in which the ink is stored and a pressure regulating device for forming a negative pressure inside the storage container is installed inside the housing, pressure control The apparatus is characterized in that it comprises a leaf spring which is integrally coupled to the side wall of the ink reservoir container to elastically press the side wall in the outward direction.

According to this, the expansion force due to the weight and volume of the ink contained in the ink reservoir and the elastic force of the leaf spring complementarily act on the side wall of the ink reservoir, whereby a negative pressure is formed inside the ink reservoir, while The size can be maintained within a certain range.

Leaf spring according to a preferred embodiment of the present invention, the holding member coupled to one side of the ink storage container; A connection part extending from a lower end of the fixing member and coupled to a lower end of the ink storage container; And a movable member extending upwardly from the connecting portion and coupled to the other side of the ink storage container, and the front end of which is elastically rotated based on the connecting portion.

In addition, the ink storage container is formed in a conical shape in which one side coupled with the fixing member is fixed to the inner wall of the housing and the upper end portion thereof has a larger cross-sectional area than the lower end portion.

The leaf spring according to another embodiment of the present invention is protruded from the bottom surface of the housing and its front end is integrally coupled to the side wall of the ink reservoir, characterized in that the side wall elastically pressurized outwardly.

In addition, the ink storage container has one side fixed to the inner wall of the housing and the upper end portion is formed in a conical shape having a larger cross-sectional area than the lower end portion, and the front end portion of the leaf spring is coupled to the inclined side surface.

In addition, it is preferable to compensate for the difference between the elastic force of the leaf spring and the self-weight of the ink as the mass is fixed to the front end of the leaf spring so that the amount of ink accommodated in the ink storage container is varied.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 3 schematically shows the structure of an ink cartridge according to an embodiment of the present invention.

According to the figure, the ink cartridge 30 includes a housing 31, an ink storage container 35, and a pressure regulating device 40.

An ink supply port 31a is formed on the bottom surface of the housing 31, and an air inlet port (not shown) communicating with the atmosphere is formed on the outer surface of the housing 31. The ink supply port 31a connects the ink discharge port 36 of the ink storage container 35 installed inside the housing 31 with the nozzle unit (not shown) installed below the housing 31. The air inlet is formed so that air can flow in and out from the outside, thereby forming an environment having the same air pressure as the atmosphere inside the housing 31.

The ink reservoir 35 is formed in a bag shape of a flexible flexible material. Accordingly, the ink storage container 35 varies in volume depending on the amount of ink stored therein, and when ink is injected from the outside, the ink storage container 35 is expanded to be larger than the volume before the ink is stored so that the outer wall is initially initialized. You have a contractile force to go back. In the present embodiment, the ink storage container 35 has one side coupled to the inner wall of the housing 31 so as to expand the outer wall of the ink storage container 35 using the weight of ink, and the upper end of the ink storage container 35 has a cross-sectional area of the lower end than that of the lower end. It is formed into a large cone. According to this, the side surface of the ink storage container 35 which is not coupled to the housing 31 side has a predetermined inclination angle θ (see FIG. 4A) with respect to the inner wall of the housing 31, and the inside of the ink storage container 35. The center of gravity of the ink contained in the is placed on top of the inclined side. In addition, the inclined side surface of the ink storage container 35 is formed into a curved surface so that the ink self-weight can be better affected. Therefore, the inclined side of the ink storage container 35 is pressurized to expand downward by the weight of ink contained in the ink storage container 35, and this expansion pressure is the outer wall of the ink storage container 35 to be contracted. Part of which is offset.

On the other hand, the ink storage container 35 can be modified in various forms. For example, the center of gravity of the ink accommodated in the ink storage container 35 is formed such that the cross-sectional area is narrowed as it progresses downward, such as being formed in a rectangular cylinder so as to be inclined only on one side that is not coupled to the housing 31. If it is located on the inclined side of the storage container 35 can be variously modified.

The pressure regulating device 40 is to allow the negative pressure to be more easily formed in the ink storage container 35 while maintaining the magnitude of the negative pressure within a predetermined range, and the pressure regulating device 40 in the present embodiment. Includes a mass 43 and a support member 41.

The mass 43 is fixed to the side of the ink reservoir 35 inclined with respect to the inner wall of the housing 31. Here, the mass 43 is preferably installed at the upper end of the inclined side of the ink reservoir 35 to effectively expand the outer wall of the ink reservoir 35 using its own load.

The support member 41 is for preventing the mass body 43 from falling down in the direction where it is installed so as not to expand the ink storage container 35 but to shrink it, and the ink storage container having the mass body 43 installed therein. It protrudes from the bottom surface of the housing 31 so as to extend along the inclined side of the 35 to support the mass 43. The support member 41 is fixed to the bottom surface of the housing 31 by inserting the fixing protrusion 41a formed at the proximal end into the fixing hole 31b formed at the bottom surface of the housing 31. Here, the support member 41 is bonded to the side surface of the ink storage container 35 to be integrally formed with the ink storage container 35, so that the expansion force due to the weight of the mass 43 is increased by the outer wall (of the ink storage container 35). 37) can be uniformly acted on.

Hereinafter, the operation of the pressure regulator 40 in the present embodiment will be described with reference to FIGS. 4A and 4B.

When the ink 70 is injected into the ink reservoir 35, as shown in FIG. 4A, the ink reservoir 35 is expanded by the volume and weight W of the ink 70 to be injected. At this time, the outer wall 37 of the ink storage container 35 is further pressurized downward by the weight W _w of the mass 43, and thus the ink storage container 35 is further expanded to thereby expand the ink storage container 35. ), A pressure having a magnitude smaller than the atmosphere formed in the interior 32 of the housing 31, that is, a negative pressure is formed. Here, the mass of the mass 43 preferably has a size capable of forming a negative pressure having a size within the ink supply range within the ink storage container 35 as shown in FIG. 2.

On the other hand, when the ink 70 contained in the ink storage container 35 is consumed, as shown in FIG. 4B, the ink storage container 35 becomes smaller in volume and weight of the ink 70. This will reduce the volume. However, also at this time, the outer wall 37 of the ink storage container 35 is pressed outward by the weights W 'and _Ww ' of the ink 70 and the mass 43.

Here, the mass 43 is fixed to the support member 41. Accordingly, most of the force W _w1 of the direction component parallel to the inclined side surface 38 of the ink storage container 35 among the weight W _w of the mass 43 is supported by the support member 41. . Accordingly, the external force to substantially expand the outer wall 37 of the ink storage container 35 acts in a direction perpendicular to the outer wall 37 of the ink storage container 35 among the weights W _w of the mass 43. Force W _w2 . Since the magnitudes of the forces W _w2 and W _w2 ′ acting perpendicularly to the outer wall 37 of the ink storage container 35 vary in the volume of the ink storage container 35 as shown in FIGS. 4A and 4B. It is variable as follows. That is, when the volume of the ink storage container 35 is large, the force W _{w2 in} the direction perpendicular to the outer wall 37 of the ink storage container 35 in a size similar to the size of the weight W _w of the mass body 43. The outer wall 37 of the ink storage container 35 is pressed in the direction of the bottom surface of the housing 31, and when the volume of the ink storage container 35 is small, it is of a size similar to the magnetic weight W _w of the mass 43. A force W _w1 ′ in a direction parallel to the inclined side surface 38 of the ink storage container 35, which is a force, is supported by the support member 41, thereby expanding force applied to the outer wall 37 of the ink storage container 35. (W _w2 ') also becomes smaller. Accordingly, the magnitude of the external force acting on the outer wall 37 of the ink storage container 35, that is, the expansion force, is elastically variable according to the storage amount of the ink 70, so that the magnitude of the negative pressure generated inside the ink storage container 35 is increased. It can prevent a sudden change.

On the other hand, in the present embodiment has been described that the support member 41 is formed of a rigid material such as steel, the support member 41 may be formed of a variety of materials, of course. In particular, when the support member 41 is formed of a leaf spring having an elastic force, when the volume of the ink storage container 35 decreases, the support member 41 pivots relative to the fixing protrusion 41a so that the elastic force is increased so that the ink The outer wall 37 of the ink reservoir 35 may be pressed in the direction in which the reservoir 35 is expanded. According to this, since the expansion force for pressing the outer wall 37 of the ink storage container 35 to the outside becomes large, it is possible to easily form a negative pressure inside the ink storage container 35.

Hereinafter, an ink cartridge according to another embodiment of the present invention will be described with reference to FIG. 5. Here, the structure and operation of the housing 51 and the ink storage container 55 is the same as the above-described embodiment (see Fig. 3), so the detailed description thereof will be omitted.

According to the drawings, the pressure regulating device 60 in this embodiment includes a fixing member 61, a connecting portion 62 and a movable member 63, and the lower and side surfaces of the ink storage container 35 in the longitudinal direction. It consists of a leaf spring 60 formed in the shape of a tong to surround. At this time, the leaf spring 60 can be installed on both the inner and outer sides of the ink storage container 35, and in this embodiment, the leaf spring 35 provided on the outer side of the ink storage container 35 will be described as an example.

The fixing member 61 is coupled to a side fixed to the housing 51 among the sides of the ink storage container 55. In addition, the connection part 62 has a through-hole 60a through which the ink outlet 56 of the ink storage container 55 is connected to a central portion thereof, and extends from the lower end of the fixing member 61 to form the ink storage container 55. Surround the bottom of the. The movable member 63 extends from the connecting portion 62 and is coupled to the inclined side of the ink reservoir 35 which is not fixed to the housing 51.

The leaf spring 60 configured as described above has an ink storage container in a compressed state in the same direction as the arrow shown in FIG. 5 so that the distance between the ends of the movable member 62 and the fixing member 61 in the initial shape is narrowed. Coupled to 55. Accordingly, the leaf spring 60 coupled to the ink reservoir 55 is pressed in the direction in which the outer wall of the ink reservoir 55 is always inflated. At this time, since the ink storage container 55 is close to the initial shape of the leaf spring 60 in the expanded state, the magnitude of the pressing force is minimized, and when the volume of the ink storage container 55 decreases, the leaf spring is reduced. By 60, the magnitude of the pressing force acting on the outer wall 57 of the ink storage container 55 is increased. On the other hand, the shape of the leaf spring 60 is not limited to this embodiment can be configured in a variety of different forms, of course.

Hereinafter, operations and effects of the ink cartridge 50 according to the present embodiment will be described with reference to FIGS. 6A to 6B.

First, as shown in FIG. 6A, when the ink 70 is injected into the ink storage container 55, the ink storage container 55 expands. At this time, the outer wall 57 of the ink storage container 55 expands outward by the self-weight W of the ink 70 contained in the ink storage container 55 and the elastic force F of the leaf spring 60. You will receive an external force to be. Accordingly, the ink reservoir 55 is further expanded in the originally inflated state, so that a small magnitude of pressure, i.e., a negative pressure, is formed inside the ink reservoir 55 with respect to the atmosphere inside the housing 51.

As shown in FIG. 6B, when the ink 70 contained in the ink storage container 55 is consumed, the ink storage container 55 is contracted by its contracting force. At this time, the shrinkage of the ink storage container 65 is suppressed by the magnetic weight W 'of the ink 70 and the elastic force F' of the leaf spring 60, and thus the ink storage container 55 is stored in the ink storage container. (55) The negative pressure is formed inside the ink storage container 55 by expanding a little more than the contracted state by its contracting force.

In the ink storage container 55 operated as described above, as shown in FIG. 2, the outer wall 57 of the ink storage container 55 is expanded in order to maintain the negative pressure within a range within which ink can be supplied. The magnitude of the pressing force to be pressed must be varied according to the ink 70 storage amount. This demand is satisfied by the self weight W of the ink, which decreases when the ink 70 is consumed, and the elastic force F 'of the leaf spring 60, which increases in size when the ink storage container 55 shrinks.

7 is a side cross-sectional view schematically showing the configuration of an ink cartridge 50 'according to another embodiment of the present invention. According to the drawings, the configurations of the housing 51 and the ink storage container 55 of the ink cartridge 50 'are the same as those of the above-described embodiments, and a description thereof will be omitted.

The ink cartridge 50 'in this embodiment is characterized in that a mass 43 is further provided at the tip of the movable member 63 of the leaf spring 60. The mass 43 compensates for the elastic force F of the leaf spring 60 that decreases when the ink reservoir 55 expands, and the elastic force F of the leaf spring 60 that increases when the ink reservoir 55 shrinks. It compensates with proper force so that the difference between ') and decreasing ink weight (W') is not too large. Here, most of the force W _w acting in the direct direction on the outer wall 57 of the ink storage container 55 by the weight W _w of the mass 65 is supported by the movable member 63, and the ink Only the force (W _w2 ) acting in the direction perpendicular to the outer wall 57 of the storage container 55 is directly applied to the outer wall 57 of the ink storage container 55 to thereby form the outer wall 57 of the ink storage container 55. Inflate.

On the other hand, the operation of the ink cartridge 50 'according to the present embodiment is almost the same as that of the previous embodiment shown in Figs. 6A to 6B. However, due to the addition of the mass 65, the force for urging the outer wall 57 of the ink storage container 55 in the expanding direction during the expansion or contraction of the ink storage container 55 is variably greater. That is, when the ink storage container 55 is expanded, the ink storage container 55 is further expanded by pressing the outer wall 57 of the ink storage container 55 with a larger force by the mass 65, and the ink storage container is further expanded. When 55 is contracted, the self weight W of the ink which is rapidly reduced is compensated for by the weight of the mass 65. At this time, a force W _w having a magnitude corresponding to the total weight of the mass 65 is not applied to the outer wall 57 of the ink storage container 55, but is perpendicular to the outer wall of the ink storage container 55 ( Only the force of W _w2 is applied to the outer wall 57 of the ink reservoir 55. Therefore, when the angle θ between the bottom surface of the housing 51 and the movable member 63 of the leaf spring 60 increases as the ink storage container 55 shrinks, the ink storage container is formed by the mass 65. The magnitude of the force acting on the outer wall 57 of the 55 becomes smaller.

FIG. 8 shows a change in the magnitude of the negative pressure formed in the conventional ink storage container and the ink storage container 55 of the present invention, which varies according to the consumption amount of ink contained in the ink storage container 55. As shown in FIG. Here, the section indicated by the hidden line in the drawing represents a range in which ink can be supplied from the size of the negative pressure formed in the ink storage container 55, the conventional negative pressure change is Pa, the trend of negative pressure change according to the present invention is Pb Is displayed.

According to the drawings, the size of the negative pressure formed in the ink storage container 55 within the conventionally available range increases in a substantially straight line by the spring 22 (see FIG. 1), and suddenly reaches a limit of the available range. It becomes larger so that the ink 70 can no longer be ejected.

However, according to the ink cartridge 50 'according to the present invention, not only the negative pressure increases smoothly in a curve within the available range, but also the slope becomes smooth so that the ink can be used within the available range. The consumption is increased by the interval (A). Therefore, it is possible to effectively reduce the amount of ink that is contained in the ink storage container 55 but is not injected into the nozzle unit 19 and discarded.

According to the present invention configured as described above, the expansion force acting on the outer walls (37, 57) of the ink storage containers (35, 55) is variable adjusted according to the amount of ink 70 remaining in the ink storage containers (35, 55) As a result, the magnitude of the negative pressure formed in the ink storage containers 35 and 55 may be stably maintained.

As a result, the size of the negative pressure formed in the ink storage containers 35 and 55 can be continuously maintained at a size smaller than the size of the negative pressure instantaneously formed in the nozzle unit 19, so that the ink storage containers 35 and 55 The amount of ink 70 remaining inside, but not used and discarded can be effectively reduced.

Therefore, in the case of a printer that needs to replace the ink cartridges 30, 50, and 50 ', the replacement timing of the ink cartridges 30, 50, and 50' can be extended, and the ink cartridges 30, 50, and 50 'can be extended. In the case of a printer capable of resupplying ink, it is possible to extend the period of resupplying ink to the ink storage containers 35 and 55, thereby maintaining the printer at a low cost.

While the invention has been shown and described with respect to preferred embodiments for illustrating the principles of the invention, the invention is not limited to the construction and operation as shown and described. Rather, those skilled in the art will appreciate that various changes and modifications can be made to the present invention without departing from the spirit and scope of the appended claims. Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

Claims (8)

In an ink cartridge for a printer provided with a flexible ink storage container for storing ink and a pressure adjusting device for forming a negative pressure inside the storage container, The ink reservoir is formed in a conical shape of the lower end is narrower than the upper end connected to the ink outlet, it is installed inclined with respect to the inner wall of the housing so that the weight of the ink stored therein acts eccentrically from the ink outlet, The pressure regulating device includes a leaf spring coupled to the side wall of the ink storage container and elastically pressing the side wall in an outward direction of the ink storage container. The self-weight of the ink contained in the ink storage container, the elastic force of the storage container generated by the volume change of the storage container, and the elastic force of the leaf spring are complementarily applied to the sidewall of the ink storage container. The negative pressure is formed inside the ink reservoir, while the magnitude of the negative pressure is maintained within a predetermined range. The method of claim 1, wherein the leaf spring, A fixing member coupled to one side of the ink storage container; A connection part extending from a lower end of the fixing member and coupled to a lower end of the ink storage container; And And a movable member extending upwardly from the connection portion and coupled to the other side of the ink storage container, the front end portion of which is elastically rotated based on the connection portion. The method of claim 2, wherein the ink storage container, One side coupled to the fixing member is fixed to the inner wall of the housing, and the other side coupled to the movable member is inclined with respect to the inner wall of the housing. In an ink cartridge for a printer provided with a flexible ink storage container for storing ink and a pressure adjusting device for forming a negative pressure inside the storage container, The ink reservoir is formed in a conical shape of the lower end is narrower than the upper end connected to the ink outlet, it is installed inclined with respect to the inner wall of the housing so that the weight of the ink stored therein acts eccentrically from the ink outlet, The pressure regulating device, one end is coupled to the bottom surface of the housing, the other end is coupled to the side wall of the ink reservoir container plate spring for elastically pressing the side wall of the ink reservoir vessel in the outward direction of the ink reservoir. Including; The self-weight of the ink contained in the ink storage container, the elastic force of the storage container generated by the volume change of the storage container, and the elastic force of the leaf spring are complementarily applied to the sidewall of the ink storage container. The negative pressure is formed inside the ink reservoir, while the magnitude of the negative pressure is maintained within a predetermined range. The method of claim 4, wherein the ink storage container, One side is fixed to the inner wall of the housing, the other side coupled to the front end of the leaf spring is inclined with respect to the inner wall of the housing, the ink cartridge for a printer. The method of claim 5, wherein A mass cartridge is fixedly installed at the front end of the leaf spring to compensate for the difference between the elastic force of the leaf spring and the self-weight of the ink as the amount of ink accommodated in the ink storage container is varied. In an ink cartridge for a printer provided with a flexible ink storage container for storing ink and a pressure adjusting device for forming a negative pressure inside the storage container, The ink storage container is formed in a conical shape in which one side is coupled to the inner wall of the housing and the upper end portion is larger in size than the lower end portion. The pressure regulator includes a mass body installed on the inclined side top of the ink reservoir, The expansion force by the volume and weight of the ink stored in the ink storage container and the mass of the mass are complementarily applied to the side wall of the ink storage container, whereby the negative pressure is formed inside the ink storage container, while the magnitude of the negative pressure. The ink cartridge for a printer, characterized in that is maintained within a certain range. The method of claim 7, wherein The pressure regulating device further comprises a support member for connecting the mass and the bottom surface of the frame in a direction parallel to the side of the ink storage container coupled to the mass, And the mass is rotated spaced apart from the base end of the support member by the length of the support member upon contraction or expansion of the ink reservoir.