Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1994-04-05
2001-09-11
Nguyen, Judy (Department: 2861)
Incremental printing of symbolic information
Ink jet
Controller
Reexamination Certificate
active
06286921
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink cartridge used in an ink jet printer, and an ink jet printer including an ink cartridge. Particularly, it relates to improvement of an ink cartridge and an ink jet printer that allows detection of the remaining amount of ink in the cartridge.
2. Description of the Background Art
An ink jet printer sprays out ink from a nozzle of a print head that moves parallel to an object to be printed to print out characters and images. A detachable ink cartridge as well as a nozzle are attached to the print head. The ink in the ink cartridge is sprayed out by pressurization means or electrostatic means.
When the amount of ink inside an ink cartridge is low, it is necessary to sense the low supply and identify the time to exchange the ink cartridge or to interrupt a printing process. A conventional ink jet printer and ink cartridge is provided with means to detect the amount of ink in the ink cartridge.
Means for detecting the remaining amount of ink includes a type that detects the amount of ink mechanically and electrically.
An ink jet printer will be described hereinafter including detecting means for mechanically detecting the remaining amount of ink.
FIG. 36
is a perspective view of a structure of an ink cartridge of a first conventional ink jet printer. Ink is stored in an accommodating bag
101
. Accommodating bag
101
is formed to contract in one direction according to decrease of the remaining amount of ink, and has a supply tube
102
for the outflow of ink. Accommodating bag
101
is placed in a box type cartridge case
103
with supply tube
102
projecting outwards. A plate
104
for detecting the remaining amount of ink is attached to the contraction region of accommodating bag
101
in cartridge case
103
. A portion of plate
104
protrudes outward from a rectangular opening
105
formed in a longitudinal direction which is identical to the contraction direction of accommodating bag
101
.
According to an ink cartridge of the above-described structure, plate
104
travels within rectangular opening
105
in response to the contraction of accommodating bag
101
as the remaining amount of ink becomes lower. A switch for detecting whether there is ink or not is provided in the main body of the ink jet printer to which this ink accommodating unit is loaded. When plate
104
travels a predetermined amount according to decrease of the remaining amount of ink, this switch is turned on to inform that the ink is exhausted.
A conventional ink jet printer having means for electrically detecting the remaining amount of ink will be described hereinafter. A conventional ink jet printer had electrodes provided in the proximity of an ink supply hole at the lower portion of an ink cartridge. A method is employed for detecting the remaining amount of ink by measuring the electrical resistance of the ink. According to this detection method, the electrical resistance between the electrodes increases when there is no ink around the electrodes. A low supply of ink can be identified according to the measured value of electrical resistance between the electrodes. Two types of ink jet printers detecting decrease in the amount of ink in an ink cartridge using such a detection method will be described hereinafter.
A second conventional ink jet printer including detection means for detecting electrically the remaining amount of ink will be described with reference to
FIG. 37
showing a sectional view of an ink cartridge.
Referring to
FIG. 37
, an ink permeable sponge
4004
having a porous member impregnated with ink is installed in a container
4001
. A pair of electrodes
4006
are provided at the lower portion of container
4001
as an out-of-ink sensor. An ink supply hole
4010
is provided at the lower portion of container
4001
communicating with a nozzle of a print head not shown. A pore is provided at the upper portion of container
4001
. This pore
4011
supplies air into the ink cartridge to assist ink flow during the usage of the ink cartridge.
A third conventional ink jet printer having detection means for electrically detecting the remaining amount of ink is disclosed in Japanese Patent Laying-Open No. 3-277558. According to this ink jet printer, an ink accommodating unit includes an ink reservoir having a porous material for impregnating ink and an ink fountain communicating with the ink reservoir. Ink is supplied to a print head from the ink fountain.
Electrodes are provided in a portion of the porous material in the ink reservoir and in a portion of the ink fountain. A remaining amount detection unit is provided for detecting the remaining amount of ink according to the change in resistance between the electrodes.
When ink in the ink accommodating unit becomes nearly exhausted in the ink jet printer of the above-described structure, air will be introduced into the joint portion between the ink reservoir and the ink fountain to reduce the area of the joining portion, whereby resistance between the electrodes suddenly increases.
In this ink jet printer, the characteristics of the relationship between the remaining amount of ink and the resistance between the electrodes is obtained previously, and the value of the change in resistance when the ink is near exhaustion is previously set in the remaining amount detection unit. In the remaining amount detection unit, the change in the resistance between the electrodes is detected, whereby that change and a preset value of change are compared. Determination is made that the ink is near exhaustion when the values match.
The above-described conventional ink jet printers have problems as set forth in the following regarding detection of the remaining amount of ink. The above-described first conventional ink jet printer detecting mechanically the remaining amount of ink had a problem that the detection precision is low since the deformation characteristics of accommodating bag
101
differs from bag to bag.
In the ink cartridge of the above-described second conventional ink jet printer, sufficient spacing between electrodes
4006
is necessary in order to detect reduction of the amount of ink on the basis of increase in electrical resistance between electrodes
4006
. If the spacing between electrodes
4006
is not sufficient, ink will remain between the electrodes, leading to a problem that decrease in ink could not be detected. Also, there is a problem that the size of the ink cartridge could not be reduced. Furthermore, when ink is permeated into a sponge or the like, there was a possibility of decrease in the amount of ink not being able to be detected due to residue ink in the sponge.
In the third conventional ink jet printer detecting electrically the remaining amount of ink, the characteristics of the relationship between the remaining amount of ink and the resistance is non-linear. Detection of the remaining amount of ink on the basis of comparison between a measured value and a set value of the change in resistance obtained by such characteristics was not reliable, leading to a problem of low detection accuracy. There was also a problem that the structure of the ink remaining amount detection system is complicated since the measured value and the set value regarding the change of resistance have to be continuously compared.
SUMMARY OF THE INVENTION
An object of the present invention is to obtain reliable detection of ink exhaustion in an ink cartridge of an ink jet printer.
Another object of the present invention is to improve detection precision of the remaining amount of ink without making complicated the structure associated with detection of the remaining amount of ink.
An ink cartridge of an ink jet printer according to the present invention includes a container for storing liquid. Ink and an ink exhaustion detecting liquid are stored in the container.
The ink exhaustion detecting liquid is accommodated within the container to detect ink exhaustion according to the ink exhaustion detecting liquid. Therefore, detection of exhaustion of
Fukushima Kouichi
Higashio Takayuki
Koyama Kazuya
Morimoto Shigenori
Ochi Norihiro
Nguyen Judy
Saunders Kevin
Sharp Kabushiki Kaisha
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