JP2929792B2 - Ink tank remaining amount detector - 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 jet printer, and more particularly to a device for detecting the remaining amount of an ink tank which is detachably mounted on a print head and supplies ink to the print head.

[0002]

2. Description of the Related Art As a device for detecting the remaining amount of ink in an ink tank, as described in JP-A-2-3322, an electrode is provided in an ink tank, and the electrodes are energized.
Many proposals have been made to detect the presence or absence of ink based on a current value flowing through the ink. Japanese Patent Application Laid-Open No. 2-19 / 1990 discloses an ink jet cartridge of a separated ink tank type.
As described in Japanese Patent No. 8862, there has been proposed an apparatus that detects presence / absence of ink using an electrode provided on a head side. As the remaining ink amount detecting device, there have been proposed those which detect ink pressure, those which detect transmitted light of ink, and the like, in addition to those based on the value of current supplied to the ink. As described in JP-A-58-194552, a mechanism having a simple mechanism for visually confirming ink in an ink tank has been proposed.

However, the above-described conventional ink remaining amount detecting device has the following disadvantages. In the case of detecting the presence or absence of the ink based on the current value, it is necessary to detect the presence of the ink by applying a pulsed voltage or an AC voltage in order to prevent the electrolysis of the ink, and the detection circuit becomes complicated and expensive. In the ink cartridge of the separated ink tank type, the ink tank is disposable, but if the detection electrode is provided in the ink tank, the ink tank becomes expensive. Also,
When air bubbles are mixed in the head, even if ink remains in the ink tank, it is erroneously detected as running out of ink. Even if the detection is performed normally, since the ink in the ink tank runs out and the ink in the head section runs out, there is also a problem that air bubbles easily enter the head section when the remaining amount is detected. Ink cartridges of conventional ink jet printers include, as shown in JP-A-63-87242.
By storing the ink to be sent to the print head in an absorbent porous material such as polyurethane foam filled in the housing, it is possible to stably send ink to the print head regardless of the vibration of the printer. is there. The remaining amount of ink contained in such a porous material is
It should be seen as a concentration difference of the porous material, but the ink does not completely disappear from the porous material, and the porous material is dyed by the ink dye, and cannot be visually confirmed accurately. . The value of the current flowing through the ink in the ink tank changes stepwise depending on whether or not the ink touches the electrode, and thus the detection is easy. However, when the inside of the ink tank is filled with a porous material such as a sponge holding the ink, the electric resistance of the porous material changes continuously depending on the content of the ink. It is not clear and it is difficult to increase the detection accuracy.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to visually check the remaining amount of ink in an ink tank filled with a porous material such as sponge with high accuracy. It is an object of the present invention to provide a device for detecting the remaining amount of ink that can be used.

[0005]

According to the present invention, in an ink tank filled with a porous material such as sponge, at least a part of the wall surface of the ink tank is formed of a light-transmitting member, and the light-transmitting member is formed of a light-transmitting member. A groove having regions having different capillarities is formed on the inner surface of the formed ink tank wall.

[0006] The grooves formed in the light transmitting member of the ink tank are grooves having different depths and can be arranged in the order of the depth. The inner surface of the groove formed in the light transmitting member of the ink tank may be roughened.

[0007]

[Function] When a capillary is brought into contact with the surface of a sponge containing ink, the state of ink entering the groove formed in the capillary changes due to the magnitude relationship between the capillary force of the sponge and the capillary force of the groove in the ink tank wall. I do. That is, the capillary force of the sponge is weak when the amount of ink contained in the sponge is large, and is strong when the amount of ink is small. If the capillary force inside the sponge is weak, the capillary force of the groove will prevail and the groove will be filled with ink. When the wall surface of the ink tank is formed of a light transmitting member and the groove is visually observed from the outside, the groove can be recognized as black, and the ink inside the groove is confirmed.

As the ink inside the sponge decreases, the capillary force inside the sponge increases. For example, if a plurality of grooves having different capillarities are provided, as the sponge's capillary force increases, ink in the grooves having weaker capillarity is absorbed by the sponge. When the groove not filled with ink is visually observed from the outside, light is reflected on the inner surface of the groove, and thus it is confirmed that the ink has run out in the groove.

In this way, the groove in which ink is visually recognized changes according to the amount of ink contained in the sponge, and the remaining amount of ink in the ink tank (sponge) can be known.

The porous material is, of course, arranged so as not to fill the inside of the formed groove, and the shape of the groove is determined by determining the width, the depth, or both. , Capillary force can be selected. As described above, a plurality of grooves having different capillary forces may be provided, or one groove may have a stepwise or continuous difference in capillary force.

[0011]

1 is a schematic structural view of an ink jet head for explaining an embodiment of an ink tank of the present invention. FIG. 1A is a perspective view, FIG. 1B is a front view, and FIG. The figure is a side view. In the figure, 1 is a print head, 2 is a heat sink, 3 is a sub ink tank, 4 is an ink tank, 5 is a sponge, 6 is an air communication hole, 7 is a remaining amount observation window, and 8 is a groove. The ink jet head is roughly divided into a recording head portion and an ink tank having a large capacity that can be attached to and detached from the recording head portion. The recording head includes a print head 1 and a heat sink 2 to which the print head is attached.
And a sub-ink tank 3 having a small capacity and containing a sponge therein, and a wiring section (not shown) for supplying an electric signal to the print head. At least a part of the ink tank 4 is a transparent remaining amount observation window 7 so that the inside of the ink tank 4 can be observed. Ink tank 4
The inside is filled with sponge and ink, and the sponge is in close contact with the transparent remaining amount observation window. The recording head and the ink tank 4 are connected by a joint, and the ink in the ink tank 4
It is supplied to the recording head section via a joint. The ink in the ink tank is consumed with printing, and when the ink runs out, the ink tank is replaced and the ink is supplied from the new ink tank to the recording head unit. Therefore, confirmation of the presence or absence of ink in the ink tank is important in determining the time to replace the ink tank. The remaining amount observation window 7 of the ink tank 4 of this embodiment is configured as a transparent observation unit using acrylic.

FIG. 2 is a sectional view of a part of the remaining amount observation window 7 cut in a direction perpendicular to the groove. The plurality of grooves 8 are sponge 5
Is formed on the surface in contact with. In this embodiment, the groove 8 has a semicircular cross section and a depth (radius) of 100 to 100.
1000 μm. The sponge 5 placed in the ink tank is a urethane foam having a pore size of about 300 μm or a PVA foam, and has a porosity of about 80%. Initially, the ink tank 4 is filled with about 70% of the ink tank capacity. In this state, all the grooves 8 provided in the transparent observation section of the remaining amount observation window 7 are filled with ink, and the fact that the grooves 8 are filled with ink is observed through the transparent observation section.
With the consumption of the ink, the ink in the deep groove portion is sponge 5
When the ink is reduced to about 20% of the initial value, the ink is not observed in the groove having a depth of 200 μm or more. It is at this level that the printing is deteriorated due to the lack of the ink, and whether or not the groove portion having a depth of 200 μm is filled with the ink can be used as an index indicating the replacement time of the ink tank.

FIG. 3 schematically shows the relationship between the ink consumption and the groove depth. The horizontal axis shows the remaining amount of ink (%), and the vertical axis shows the relative depth of the groove. The relationship between the remaining amount of ink and the filling of the groove with ink changes depending on the material of the remaining amount observation window, surface roughness, sponge density, sponge material, and the like. As the material of the wall of the remaining amount observation window, besides acrylic, glass, polycarbonate, or the like can be used. However, the material of the wall portion does not have to be completely transparent, and it is only necessary that the material be translucent. For example, a cloudy material may be used.

The cross-sectional shapes of the groove portions are, in addition to the semicircular groove shown in FIG. 2, a V-shaped groove 8a shown in FIG. 4A, a rectangular groove 8b shown in FIG. 4B, and FIG. 4C. The groove 8c having a shape obtained by combining the V-shape and the rectangle may be used. These grooves may have different widths and / or depths to alter the capillary forces. In the case of a rectangular groove, it is easy to change the width or the depth independently. In the case of a V-shaped groove,
By changing the apex angle, the width or depth can be independently changed. These grooves are provided so that the sponge 5 does not enter the grooves.

If the surface of the groove is finely roughened, light is irregularly reflected at the interface of the groove, and the state of ink filling in the groove can be seen with high contrast.

As shown in FIG. 5, when the grooves are arranged in order from a shallow groove to a deep groove, the remaining amount may be easily visually recognized. As described above, when a plurality of grooves are provided, an appropriate arrangement order such as bottom to top, top to bottom, right to left, and left to right can be adopted. The direction of the groove is
As described in FIG. 1, the direction is not limited to the horizontal direction, and may be a vertical direction or an inclined direction as shown in FIG. It may be concentric as shown in FIG.

The width and / or depth of the groove may be changed stepwise or continuously using one groove.

[0018]

As is apparent from the above description, according to the present invention, instead of directly detecting the ink inside the sponge, the inside of the groove provided on the wall of the ink tank constituted by the light transmitting member is not detected. Is visually confirmed, the determination is reliable. In addition, since the configuration is simple, only a groove is provided on the wall surface of the ink tank, and no special electrode or detection circuit is required, there is an effect that the cost is low.

Further, since the remaining amount of the ink in the ink tank can be detected instead of the recording head, highly accurate detection can be performed. The use of the grooves having regions having different capillarities also has an effect that the consumption of the ink in the ink tank can be quantitatively detected, not as binary information.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of one embodiment of the present invention;
(A) is a perspective view, (B) is a front view, and (C) is a side view.

FIG. 2 is a sectional view of an embodiment of a remaining amount observation window.

FIG. 3 is an explanatory diagram of a relationship between an ink consumption amount and a groove depth.

FIG. 4 is a sectional view of an embodiment in which the shape of the groove is different.

FIG. 5 is a cross-sectional view showing an arrangement order of grooves according to the embodiment of the present invention.

FIG. 6 is a front view showing an arrangement direction of grooves according to another embodiment of the present invention.

FIG. 7 is a plan view showing an arrangement of another embodiment of the present invention.

[Explanation of symbols]

1 Print head, 2 heat sink, 3 sub ink tank, 4 ink tank, 5 sponge, 6 atmosphere communication hole, 7 remaining amount observation window, 8 groove.

Claims (1)

(57) [Claims] 1. An ink tank filled with a porous material such as a sponge, wherein at least a part of a wall surface of the ink tank is formed of a light transmitting member, and an inner surface of the ink tank wall formed of the light transmitting member is provided. A remaining amount detection device for an ink tank, wherein a groove having regions having different capillarities is formed in the groove.