Information
-
Patent Grant
-
6767075
-
Patent Number
6,767,075
-
Date Filed
Monday, September 10, 200122 years ago
-
Date Issued
Tuesday, July 27, 200419 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Meier; Stephen D.
- Stewart, Jr.; Charles
Agents
-
CPC
-
US Classifications
Field of Search
US
- 347 19
- 347 14
- 347 86
- 347 85
- 347 6
- 347 5
- 347 7
- 347 23
- 347 91
- 347 12
- 347 10
- 347 11
- 347 84
- 347 77
- 250 2221
- 250 229
- 073 323
- 073 327
-
International Classifications
-
Abstract
An image forming device capable of detecting the presence/absence of ink as well as whether an ink tank is mounted. A detachable ink tank 32 on a carriage 31 includes a prism 32C, and a reflective optical sensor 33 detects the presence/absence of ink depending on the difference in refractive index between the two states, that is, filled with ink and empty. A reflector lever 35, movable in response to the ink tank 32 being mounted or not, is provided on the bottom of an ink tank holder 34. The reflector lever 35 has one end fixed on a lower part of the ink tank and the other end that is a free end consisting of a triangular reflector 35D. The reflector lever 35 is normally urged upward by a resilient member 35A, and it will not direct the reflection toward the sensor 33 in the absence of the ink tank whereas it is deformed in the presence/absence of the ink tank to direct the reflection toward the sensor 33. As a result, the presence/absence of the ink tank is detected.
Description
TECHNICAL FIELD
The present invention relates to a method for detecting, in an ink-jet image forming device, the presence/absence of ink in a detachable ink tank that has paths through which ink is supplied to ink-jet nozzles and for detecting the presence/absence of the ink tank.
BACKGROUND ART
In accordance with a conventional ink-jet print method, an image may be formed by ejecting ink on an on-demand basis. Print images have changed from monochromatic images to color images and, as color printing becomes more popular, a lot of image forming devices have detachably structured ink tanks, each for cyan, magenta, yellow, light cyan, light magenta, light yellow and black. Ink in those colors is stored in separate ink tanks. In general, an ink container that may be detachably mounted on an ink-jet head with ink jet nozzles provided thereon is called an ink tank, while a unit integrally composed of a head with an ink container is called an ink cartridge. In this specification, they are both called ink tanks.
Ink in those ink tanks is consumed differently and, the user must individually exchange exhausted ink tanks or replenish an exhausted ink tank through a path.
Japanese Patent Laid-Open Publication No. Hei 8-108543 and Japanese Patent Laid-Open Publication No. Hei 9-226149 disclose a technique wherein an optical reflector prism located at the bottom of an ink tank is combined with a reflective optical sensor to sense the ink.
With reference to FIGS.
1
(
a
)-
1
(
d
), the principle of an ink sensing operation performed by the combination of the reflector prism and the reflective optical sensor will be described.
When a prism-structured ink sensor window is observed with a reflective optical sensor
33
composed of an emitter
21
and a receiver
22
of an infrared ray, the light from the emitter
21
does not reach the receiver
22
as shown in FIG.
1
(
a
) if no object is present. Also, when a non-prism-structured object
23
is in the sensing position of the optical reflective sensor as shown in FIG.
1
(
b
), the light from the emitter
21
does not reach the receiver
22
either. In addition, when liquid (ink) is present in the prism-structured part as shown in FIG.
1
(
c
), the incident ray is refracted at the interface because of a refractive index between the prism-structured member (glass, polypropylene, etc.) and the liquid. At this time, the refractive index is represented by n (α→β)=sin α/sin β(>1), where α is the incident angle and β is the refractive angle. As disclosed in Japanese Patent Laid-Open Publication No. Hei 7-164626, the refractive index (n) of air with respect to ideal gas is represented as n=about 1.0, the refractive index (n) of ink as n=about 1.4, and the refractive index (n) of polypropylene as n=about 1.5. Therefore, the polypropylene to ink refractive index n (poly→ink)=1.4/1.5≈0.93≈sin 68°/sin 90°, and polypropylene to air refractive index n (poly→air)=1.0/1.5≈0.67≈sin 42°/sin 90°.
This means that, when the polypropylene-to-ink incident angle is 68°, the refractive angle is 90°, that is, the incident ray is refracted in the direction of the interface vector at the interface between two objects (this incident angle is called the critical angle) and that, when the incident angle α>68°, the incident ray makes a total internal reflection.
This also means that, when the polypropylene-to-air incident angle is 42°, the refractive angle is 90°, that is, the incident ray is refracted in the direction of the interface vector at the interface between two objects and that, when the incident angle α>42° (critical angle), the incident ray makes a total internal reflection.
Based on this principle, creating a prism-structured polypropylene ink tank container, whose incident angle of the infrared ray from the emitter
21
is 42°<α<68°, and installing the container as described above causes the light to refract when ink is present, and causes the light to make a total internal reflection when no ink is present. Therefore, when no ink is present in the prism-structured part as shown in FIG.
1
(
d
), that is, when air is present there, a total internal reflection occurs and light from the emitter
21
reaches the receiver
22
to indicate that no ink is present.
However, when no ink tank is present on the holder (FIG.
1
(
a
)), the same result is obtained as when an ink tank fully filled with ink is installed (FIG.
1
(
c
)). Therefore, if no measure is taken, there is a possibility that, when no ink tank is present, the sensor senses that ink is present and, as a result, printing is done with no ink supplied to the print head (nozzles). This could damage the nozzles of the recording head of an ink-jet image forming device because of overheating, causing problems such as a head damage.
In view of the foregoing, it is an object of the present invention to provide an image forming device capable of detecting the presence/absence of ink, as well as whether an ink tank is mounted.
DISCLOSURE OF INVENTION
An image forming device according to the present invention for forming an image with an ink jet method comprises an ink tank detachable on a carriage; a prism disposed in the ink tank, the prism being covered with ink when the tank is filled with ink and being exposed when the tank is empty; an optical ink sensor that has a light emitter for projecting light onto the prism and a light receiver for receiving a reflected light of the projected light to detect a presence/absence of ink in the ink tank; and a reflector movable between a first position and a second position according to whether or not the ink tank is installed on the carriage, wherein the reflector, in the second position with the ink tank installed, reflects the light from the optical ink sensor back to the optical ink sensor and wherein the reflector, in the first position with no ink tank installed, does not return the light from the optical ink sensor back to the light receiver.
This allows an image forming device to detect the presence/absence of ink reliably, as well as a state regarding whether an ink tank is mounted.
The reflector comprises, with respect to the optical ink sensor, a reflective surface similar in function to the prism, and the optical ink sensor is used both to detect the presence/absence of ink and to detect the presence/absence of the ink tank. This configuration reduces the number of required parts.
The image forming device may further comprise an optical ink tank sensor for detecting a presence/absence of the ink tank such that separate sensors are used to detect the presence/absence of the ink and the presence/absence of the ink tank, the optical ink tank sensor including a light emitter for projecting light onto the reflector and a light receiver for receiving a reflected light of the projected light.
The configuration eliminates the need for the relative movement of the sensor with respect to the ink tank, allowing both ink and the ink tank to be detected at the same time. Providing separate sensors, one for each detection, increases freedom in the reflector configuration.
More specifically, the carriage may include an ink tank holder for holding the ink tank and a resilient member normally urging the movable reflector in one direction for placing the reflector in the first position, one end of the reflector being supported on the ink tank holder such that when the ink tank is installed in the ink tank holder, the reflector is pressed down against a resilient power of the resilient member to place the reflector in the second position.
The use of the resilient member enables the reflector position to be changed and, at the same time, allows the ink tank in the ink tank holder more securely.
The reflector may have a part with the same material and the same structure as those of the prism installed on an inside bottom of the ink tank.
The resilient member may be a plate spring formed by using a part of the reflector. Of course, a spring separate from the reflector may also be used.
The prism may be constructed and placed such that, a ridge line of the prism is parallel with a scanning direction of the carriage and when the ink in the ink tank reaches at least near an empty state, an interface between the ink and air moves on the ridge as the ink decreases. This allows the amount of ink to be detected.
Another image forming device according to the present invention for forming an image with an ink jet method comprises an ink tank detachable on a carriage; a prism disposed in the ink tank, the prism being covered with ink when the tank is filled with ink and being exposed when the tank is empty; an optical ink sensor that has a light emitter for projecting light onto the prism and a light receiver for receiving a reflected light of the projected light to detect a presence/absence of ink in the ink tank; a reflector provided on an outer surface of the ink tank; and an optical ink tank sensor that has a light emitter for projecting light onto the reflector and a light receiver for receiving a reflected light of the projected light to detect a presence/absence of the ink tank, wherein the reflector, with the ink tank installed, reflects the light from the optical ink tank sensor back to the optical ink tank sensor and wherein the reflector, with no ink tank installed, does not return the light from the optical ink tank sensor back to the light receiver.
This is a case wherein the reflector is provided on the ink tank itself. This reflector may record thereon information of individual ink tanks that are readable by the optical ink tank sensor.
BRIEF DESCRIPTION OF DRAWINGS
FIGS.
1
(
a
)-(
d
) are diagrams showing the principle of ink detection with a combination of a light reflective prism and a reflective optical sensor;
FIG. 2
is a diagram showing the general configuration of a carriage and its associated components of the image forming device shown in
FIG. 3
;
FIG. 3
is a block diagram showing the general configuration of an image forming device in an embodiment of the present invention;
FIG. 4
is a diagram showing the configuration of an ink tank
32
and an ink tank holder
34
for detecting ink and an ink tank in the embodiment of the present invention;
FIG. 5
is a side view viewed from arrow A in
FIG. 4
;
FIGS.
6
(
a
)-(
c
) are a top view (
a
) and a front view (
b
) of the reflector lever
35
in
FIG. 5 and a
side view (
c
) of another configuration example of the reflector lever
35
;
FIGS.
7
(
a
),
7
(
b
), and
7
(
c
) are diagrams showing the output of ink detection and ink tank detection in the embodiment of the present invention;
FIGS.
8
(
a
),
8
(
b
), and
8
(
c
) are diagrams showing the use of a single optical ink sensor
33
in the embodiment of the present invention;
FIGS.
9
(
a
) and (
b
) are diagrams showing a configuration example of a reflector lever
50
that is a modification of the reflector lever
35
in the embodiment of the present invention;
FIG. 10
is a block diagram showing the general configuration of an image forming device in a second embodiment of the present invention;
FIG. 11
is a general configuration diagram showing a carriage and its associated components in the embodiment shown in
FIG. 10
;
FIG. 12
is a diagram showing the configuration of ink and ink tank sensor in the embodiment shown in
FIG. 10
;
FIG. 13
is a side view viewed from arrow A in
FIG. 11
;
FIG. 14
is a diagram showing a configuration example of a reflector sensor
16
corresponding to the configuration shown in
FIG. 13
;
FIGS.
15
(
a
) and (
b
) are diagrams showing an modification of the reflector lever in the embodiment shown in
FIG. 10
;
FIG. 16
is a diagram showing a configuration example of an ink tank holder using the reflector lever shown in
FIG. 15
;
FIG. 17
is a diagram showing a configuration example of the reflector according to the present invention;
FIG. 18
is a diagram showing the configuration of a prism and the configuration of a sensor for detecting the presence/absence of ink according to the present invention;
FIG. 19
is a side view viewed from arrow A in
FIG. 18
; and
FIGS.
20
(
a
) and (
b
) are a diagram (
a
) and its side view (
b
) showing the configuration of a sensor corresponding to the configuration shown in FIG.
18
BEST MODE FOR CARRYING OUT THE INVENTION
Some preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. It is to be understood that the embodiments are shown and described as examples and that various modifications or changes may be made.
In the description below, it is assumed that an ink sensor window is prism-structured and that an optical reflective sensor for monitoring this part is a prism-compatible reflective optical sensor.
FIG. 2
is a general configuration diagram showing the carriage and associated components of this image forming device.
The image forming device comprises a carriage
31
capable of moving in a direction perpendicular to the media transport direction. This carriage
31
carries a plurality of ink tanks
32
thereon each having ink paths through which ink is supplied to the ink-jet nozzles. Each ink tank
32
has an ink sensor prism-structured window (that will be described below) according to the present invention. The relative movement of an optical ink sensor
33
in a direction relative to the ink sensor prism-structured windows of the ink tanks
32
is controlled by the carriage
31
.
FIG. 2
shows an example of the configuration of the carriage
31
having an additional black ink tank provided, and offset in the media transport direction, to increase the print speed in black ink. However, this configuration is neither essential nor important in the present invention. To allow all ink tanks
32
to share the sensor
22
, it is preferable that, for the additional black ink tank, the positions of a prism and the sensor window that will be described below be offset so that those positions are different from those of other ink tanks.
FIG. 3
is a block diagram showing the general configuration of the image forming device in this embodiment. The image forming device comprises a central processing unit (CPU)
1
, a temporary storage device (RAM)
2
in which various types of data or parameters are temporarily stored, a read-only non-volatile memory (ROM)
3
in which control programs corresponding to various operation modes and various types of fixed data are stored, an interface
4
that provides an interface with an external host unit
19
, an image processor
5
that processes image data sent from the host unit
19
via the interface
4
, and a jet controller
6
that controls ink to be ejected from an ink jet head
7
under control of the CPU
1
in response to print data received from the image processor
5
. The image forming device further comprises a linear scale
13
that defines the individual reference dot positions in the carriage scanning direction, a linear scale encoder
12
that works with the linear scale, a media transport motor
9
that transports media such as paper, a media transport motor controller
8
that controls the motor under control of the CPU
1
, a carriage motor
11
that causes the carriage to scan, and a carriage motor controller
10
that controls this motor under control of the CPU
1
.
The image forming device in this embodiment further comprises the optical ink sensor
33
, a prism
15
, and a reflector
17
. Preferably, the prism
15
is integrated in the ink tank
32
. In this embodiment, light projection onto, and light reception from, the reflector
17
is performed by the optical ink sensor
33
.
Although the linear scale
13
and the linear scale encoder
12
are used in this embodiment as means for sensing the amount of moving of the carriage
31
, a rotary scale installed on a motor shaft driving the carriage
31
and a rotary encoder may also be used to implement this means. Alternatively, when a stepping motor is used, this means may be implemented by counting the pulses of the stepping motor driving signal. In this embodiment, the position and speed of the carriage
31
is sensed by the linear scale encoder
12
installed on the carriage
31
, and the relative movement amount or the absolute position of the carriage
31
is sensed by the count of the output pulses from the linear scale encoder
12
. In addition, the presence/absence of ink in the ink tank is detected by controlling the operation of the carriage
31
and by scanning the prism in the ink tank
32
on the carriage with the use of the optical ink sensor
33
. As will be described below, the reflector
17
provided near the prism constitutes a part of means for detecting whether or not the ink tank
32
is on the carriage
31
.
FIG. 4
shows an example of the configuration of the ink tank
32
and an ink tank holder
34
that are used in this embodiment to detect the presence/absence of ink and the presence/absence of an ink tank.
Installing the ink tank
32
in the ink tank holder
34
causes a positioning hole
34
B on the ink tank holder
34
to be engaged with a projection
32
B on the ink tank and, at the same time, a lock
34
A of the ink tank holder
34
to be engaged with a pawl
32
A of the ink tank
32
, setting the ink tank
32
in position in the ink tank holder
34
.
A reflector lever
35
(corresponding to the reflector
17
shown in
FIG. 3
) is provided on the inside bottom of the ink tank holder
34
. As shown in
FIG. 5
showing the part indicated by arrow A in
FIG. 4
, the reflector lever
35
is supported on the wall of the ink tank holder
34
so that, with one end
35
E being as a supporting point, a free end that is the other end may rock. Also, an ink jet head
34
D is provided on the outside bottom of the ink tank holder
34
. This ink jet head
34
D is engaged with an ink tank connector
32
D of the ink tank
32
to receive the ink supply. About half of the ink tank
32
to which ink tank connector
32
D belongs is padded with a sponge-like ink absorbing member.
FIGS.
6
(
a
) and
6
(
b
) are the top view and the front view of the reflector lever
35
, respectively. As indicated most clearly in FIG.
6
(
a
), a reflector window
35
B is provided about the center of the reflector lever
35
. The light emitted by the optical ink sensor
33
reaches a prism
32
C of the ink tank
32
via a sensor window
34
C provided on the bottom of the ink tank holder and via the reflector window
35
B and, then, the reflected light is received by the optical ink sensor
33
via the reflector window
35
B and the sensor window
34
C. This configuration allows the presence/absence of ink to be detected according to the principle described above. The free end of the reflector lever
35
is normally urged upward at its bottom by a resilient member
35
A. The free end of the reflector lever
35
is projected outward from the ink tank to form a triangular reflector
35
D whose cross section looks like a cone. This conical shape matches the conical shape of a prism
32
C. When the optical ink sensor
33
is immediately below the triangular reflector
35
D, the light from the light emitter of the optical ink sensor
33
is reflected on the slope of the reflector lever
35
and is directed in the direction different from the direction in which the light is received (see FIG.
8
(
c
)). Installing the ink tank
32
in position in the ink tank holder
34
causes the reflector lever
35
to be pressed downward against the resilient member
35
A. This puts the triangular reflector
35
D of the reflector lever
35
in a state equivalent, on an optical and positional basis, to that of the prism
32
C, causing the light from the emitter
21
of the sensor
33
to be reflected twice to allow the receiver
22
to receive the light and thus making it possible to detect the presence of the ink tank
32
(see FIG.
8
(
b
)).
With reference to FIGS.
7
(
a
),
7
(
b
), and
7
(
c
), the ink detection output and the ink tank detection output will be described. As shown in FIG.
7
(
a
), when detecting the presence/absence of ink, the output of the receiver
22
is “H” if ink is present and is “L” if no ink is present. Also, as shown in FIG.
7
(
b
), when detecting the ink tank, the output of the receiver
22
is “L” if an ink tank is present and is “H” if no ink tank is present. Therefore, the combination of both outputs is as shown in FIG.
7
(
c
). That is, if an ink tank with ink is installed, the ink detection output and the ink tank detection output are “H” and “L”, respectively. Also, if an ink tank with no ink is installed, the outputs are “L” and “L”, respectively and, if the ink tank is not installed, the outputs are “H” and “H”, respectively. In this way, the states may be determined by two-bit data. This configuration allows the presence/absence of ink to be detected reliably according to the outputs of the sensor. As a result, an alarm may be issued to the user as necessary.
As shown in FIGS.
8
(
a
),
8
(
b
), and
8
(
c
), a single optical ink sensor
33
is fixed at a predetermined position on the carriage movement path. Sequentially opposing the sensor window
34
C and the triangular reflector
35
D of the ink tanks
32
, one at a time, against the light emitting-and-receiving surface of the optical ink sensor
33
allows the presence/absence of the ink tank
32
on the carriage
31
and the presence/absence of ink to be detected. Because the current position of the carriage
31
is known from the output of the linear scale encoder (
12
in
FIG. 3
) and because the positions of each ink tank
32
on the carriage
31
and each triangular reflector
35
D are also known in advance, where the carriage
31
should be positioned for detection may be identified in advance.
FIGS.
9
(
a
) and
9
(
b
) show a configuration example of a reflector lever
50
that is a modification of the reflector lever
35
. This reflector lever
50
does not require the resilient member
35
A that is an additional component. Instead, this reflector uses a part thereof as a resilient member (plate spring)
50
C. The shape and the material of the resilient member
50
C of the reflector lever determine the reaction force of this resilient member
50
C. An SUS plate with a high reflection factor, if used as the material of the reflector lever
50
, as well as a spring SUS material that is a resilient member, would make the reflector lever more slim and compact. Of course, surface processing such as plating increases the reflection factor. As shown in the side view in FIG.
6
(
c
), a reflector lever with the same material and with the same structure as those of the prism on the inside bottom of the ink tank may also be used.
Next,
FIG. 10
is a block diagram showing the general configuration of an image forming device in a second embodiment of the present invention. The same reference numerals shown in
FIG. 3
represent the same structural elements. The configuration is almost similar to that shown in
FIG. 3
but is different from the first embodiment in that a dedicated optical sensor
16
is provided for the reflector
17
. The output of the reflector sensor
16
is identified by the CPU
1
. This configuration makes it possible in this embodiment to detect the presence/absence of the ink tank
32
and the presence/absence of ink at the same time. Detecting them with separate sensors increases the freedom in the configuration of the reflector.
FIG. 11
is a diagram showing the general configuration of a carriage and associated components in the second embodiment. In this example, the optical ink sensor
33
and the reflector sensor
16
are fixed opposite to the carriage
31
in the image forming device as shown in the diagram.
FIG. 12
shows the configuration of this embodiment for detecting ink and an ink tank. The figure shows the section of an ink tank
32
viewed from arrow C in FIG.
11
. In the example in the figure, an optical ink sensor
33
is provided in front of, and adjacent to, the reflector sensor
16
. As shown in
FIG. 13
that is a section view showing a part of
FIG. 12
viewed from arrow A, the reflector lever
35
does not have a triangular reflector
35
D (
FIG. 5
) included in the configuration shown in FIG.
5
. Instead, as shown in
FIG. 14
, the light is reflected on the flat part of the surface of the reflector lever
35
. To be compatible with this configuration, the optical axes of the light emitter and the light receiver are tilted toward the center (This is the structure of a general reflective sensor having a certain focal length). In this state, the light received from the light emitter of the reflector sensor
16
via the sensor window
34
C is reflected on the surface of the reflector lever
35
, and the reflected light is directed in a direction different from the direction in which the light is received. If the ink tank
32
is set in position in the ink tank holder
34
, the reflector lever
35
is pressed downward against the force of the resilient member
35
A. This makes the light emitting/receiving surface of the reflector sensor
6
almost parallel with the reflector lever
35
, enabling the installation of the ink tank
32
to be detected. At the same time, the optical ink sensor
33
enables the presence/absence of ink to be detected via the prism
32
C.
Like the configuration in the first embodiment shown in FIGS.
9
(
a
) and
9
(
b
), a part of the reflector lever
50
may be used also in the second embodiment to configure a resilient member
50
C as shown in FIGS.
15
(
a
) and
15
(
b
).
As shown in
FIG. 16
, the reflector lever
50
may also be at a position 90° different in the rocking axis direction from that of the reflector lever in the example given above (for example,
FIG. 4
or FIG.
5
). That is, the reflector lever
50
may be extended from the supporting point in the direction indicated by arrow A.
FIG. 17
is a still another configuration example of the reflector. In this example, the reflector is provided on the ink tank
32
itself. That is, a reflective seal
32
E is attached near the prism
32
C in the ink tank
32
to allow the reflector sensor
16
shown in
FIG. 14
to detect the seal. In this configuration, the reflective seal
32
E may have an information recording function such as a bar code. By scanning this bar code with the use of the sensor
16
, the color of the ink tank
32
may be identified. In addition, additional information such as individual information may be read.
The method described above, which has the ability to detect the presence/absence of ink and an ink tank as well as the ability to read information on each ink tank and color identification information, gives better and more efficient determination results.
Although the ridge line of the prism is perpendicular to the carriage scanning direction in the above embodiment, the ridge line of the prism may be in the same direction as the carriage scanning direction and the sensor may be placed accordingly as proposed by the present applicant in Japanese Patent Application No. Hei 10-296148. Such an example is shown in FIG.
18
. Also, the side view of the configuration in
FIG. 18
, viewed from the direction of arrow A, is shown in FIG.
19
. In this example, the ridge line of the prism
32
C is in the same direction as the carriage scanning direction and, in addition, the ridge line of the prism is long and is inclined (θ in FIG.
19
) to the horizontal plane (bottom of the ink holder). As the carriage scans, the sensor window
34
C of the ink tank holder
34
is scanned in the lengthwise direction of the prism. As this scan is made, it is assumed that the distance between the optical ink sensor
33
and the prism
32
C varies only within the detection effective range. Then, by detecting a change in the output level of the sensor
33
or by calculating the position of the ink surface that forms the interface between the prism with an inclination of an angle (θ) by using the linear scale encoder described above, not only the presence/absence of ink in the ink tank
32
but also a change in the amount of ink may be checked.
As shown in the front view in FIG.
20
(
a
) and in the side view in FIG.
20
(
b
), the sensor
33
may have a contact-sliding, partially-movable detection mechanism on the inclined bottom of the ink tank
32
such that the distance between the optical ink sensor
33
and the prism
32
C remains unchanged. To implement this mechanism, the optical ink sensor
33
is supported by a resilient member and has a member that contacts the bottom of the ink tank
32
for keeping a predetermined amount of space against the sensor surface.
While the preferred embodiments of the present invention have been described, various modification and changes are possible. For example, although the prism and the ink tank are integrated into one in the embodiments, a prism and an ink tank, which are separate, may be connected.
Industrial Applicability
The present invention is applicable to the design and manufacturing of an image forming device such as an ink jet printer and a plotter. The present invention provides an easy method for detecting the presence/absence of ink using a refraction determined by ink and the material of the prism in an ink tank and for detecting an ink tank on the carriage by using a reflector near the prism, thus preventing an ink detection error which would occur when the ink tank is removed. In addition, a very simple structure of the ink tank increases the ink tank detection function and reliability. In addition, a reflective plate where information is recorded, if provided on the ink tank itself, allows the ink tank to be identified and prevents the ink tank from being installed improperly.
Claims
- 1. An image forming device for forming an image with an ink jet method, comprising:an ink tank which is detachable on a carriage; a prism disposed in said ink tank, said prism being covered with ink when the tank is filled with ink and being exposed when the tank is empty; an optical ink sensor that has a light emitter for projecting light onto said prism and a light receiver for receiving a reflected light of the projected light to detect a presence/absence of ink in said ink tank; and a reflector movable between a first position and a second position according to whether or not said ink tank is installed on said carriage; wherein said reflector, in said second position with the ink tank installed, reflects the light from said optical ink sensor back to said optical ink sensor and wherein said reflector, in said first position with no ink tank installed, does not return the light from said optical ink sensor back to said light receiver; said carriage including an ink tank holder for holding the ink tank on said carriage and a resilient member normally urging said movable reflector in one direction for placing said reflector in said first position, one end of said reflector being supported on the ink tank holder, and wherein, when the ink tank is installed in said ink tank holder, said reflector is pressed down against a resilient power of said resilient member to place said reflector in said second position.
- 2. The image forming device according to claim 1, wherein said optical ink sensor is used both to detect the presence/absence of ink and to detect the presence/absence of said ink tank.
- 3. The image forming device according to claim 2 wherein said prism is constructed and placed such that, a ridge line of said prism is parallel with a scanning direction of said carriage and when the ink in said ink tank reaches at least near an empty state, an interface between the ink and air moves on said ridge as the ink decreases.
- 4. The image forming device according to claim 2, wherein said reflector has a part with the same material and the same structure as those of said prism installed on an inside bottom of said ink tank.
- 5. The image forming device according to claim 1, wherein said reflector has a part with the same material and the same structure as those of said prism installed on an inside bottom of said ink tank.
- 6. The image forming device according to claim 1, further comprising an optical ink tank sensor for detecting a presence/absence of said ink tank such that separate sensors are used to detect the presence/absence of the ink and the presence/absence of said ink tank, said optical ink tank sensor including a light emitter for projecting light onto the reflector and a light receiver for receiving a reflected light of the projected light.
- 7. The image forming device according to claim 1, wherein said reflector has a part with the same material and the same structure as those of said prism installed on an inside bottom of said ink tank.
- 8. The image forming device according to claim 1 wherein said resilient member is a plate spring formed by using a part of said reflector.
- 9. An image forming device for forming an image with an ink jet method, comprising:an ink tank which is detachable on a carriage; a prism disposed in said ink tank, said prism being covered with ink when the tank is filled with ink and being exposed when the tank is empty; an optical ink sensor that has a light emitter for projecting light onto said prism and a light receiver for receiving a reflected light of the projected light to detect a presence/absence of ink in said ink tank; a reflector provided on an outer surface of said ink tank; and an optical ink tank sensor that has a light emitter for projecting light onto said reflector and a light receiver for receiving a reflected light of the projected light to detect a presence/absence of said ink tank, wherein said reflector, with the ink tank installed, reflects the light from said optical ink tank sensor back to said optical ink tank sensor and wherein said reflector, with no ink tank installed, does not return the light from said optical ink tank sensor back to said light receiver; and wherein said reflector has a bar code recorded on the ink tank for individual ink tanks, said bar code being readable by said optical ink tank sensor.
- 10. A method for detecting a presence/absence of ink in an ink tank of an image forming device which forms an image with an ink jet method, said method comprising the steps of:projecting light onto a prism for obtaining a first detection signal according to whether or not a reflected light is present, said prism being provided in an ink tank which is detachable on a carriage, said prism being covered with ink when the ink tank is filled with ink and being exposed when the ink tank is empty; projecting light onto a reflector for obtaining a second detection signal according to whether or not a reflected light is present, said reflector being movable between a first position and a second position according to whether or not said ink tank is installed on said carriage; and based on said first and second detection signals, detecting the presence/absence of said ink tank on said carriage and the presence/absence of the ink in said ink tank; said resilient member normally urging said movable reflector in one direction for placing said reflector in said first position, one end of said reflector being supported on the ink tank holder, and wherein, when said ink tank is installed in said ink tank holder, said reflector is pressed down against a resilient power of said resilient member to place said reflector in said second position.
Priority Claims (1)
Number |
Date |
Country |
Kind |
11/73051 |
Mar 1999 |
JP |
|
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/JP00/01701 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO00/54974 |
9/21/2000 |
WO |
A |
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Number |
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Date |
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5856833 |
Elgee et al. |
Jan 1999 |
A |
5997121 |
Alfather et al. |
Dec 1999 |
A |
6443567 |
Hayashi et al. |
Sep 2002 |
B1 |
6460962 |
Dietl et al. |
Oct 2002 |
B1 |