Information
-
Patent Grant
-
6299278
-
Patent Number
6,299,278
-
Date Filed
Thursday, February 5, 199826 years ago
-
Date Issued
Tuesday, October 9, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Fitzpatrick, Cella, Harper & Scinto
-
CPC
-
US Classifications
Field of Search
US
- 347 33
- 347 23
- 347 24
- 347 32
-
International Classifications
-
Abstract
A printer assembly providing quick and effective wiping of print heads. The printer assembly includes a carriage for holding a print head and having a slide contact, a slide having a wiper ramp, a carriage contact contactable by the slide contact of the carriage, and a wiper assembly including a base, a post extending from the base, a wiper arm, a wiper latch, a wiper holder, and a wiper blade, wherein the wiper arm is connected to the base such that the wiper arm is raised in a case that the wiper arm ramp moves laterally relative to and while in contact with the wiper arm, the wiper latch is connected to the wiper arm such that the wiper latch latches onto the post extending from the base in a case that the wiper arm is sufficiently raised, the wiper holder is connected to the wiper arm, and the wiper blade is connected to the wiper holder.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to systems for removing excess ink from ink jet print head nozzles. More particularly, the present invention relates to a system for wiping external ink from nozzle opening of an ink jet print head.
Conventional ink jet printers utilize ink jet print heads to print pixels upon a recording medium. Ink jet print heads contain ink jet nozzles which eject ink droplets onto the recording medium through nozzle openings. Over time, ink collects on or near the ink jet nozzle openings, thereby tending to clog the nozzle openings.
Due to the foregoing, many conventional ink jet printers provide systems for cleaning ink from ink jet nozzles before, during, or after printing. One such system is a wiping system, in which an element is moved across ink jet nozzle openings so as to wipe ink from the openings.
In order to clean the ink jet nozzles most effectively, such wiping cannot occur at normal print speeds. Rather, the print head must move in relation to the wiping element at a speed much slower than normal printing speeds. Accordingly, nozzle wiping slows the printing process.
For example, in conventional wiping systems, an ink jet print head is moved out of a printing area to a wiping station. At the wiping station, a wiping element is moved relative to the ink jet print head so as to wipe the nozzles of the ink jet print head, the wiping element is lowered, and printing resumes. Accordingly, what is needed is a system for quickly and effectively wiping ink jet nozzles.
Ink jet nozzle wiping is more problematic in a case of dual-head ink jet printing. Dual-head ink jet printers utilize two ink jet print heads, each print head having a set of ink jet nozzles. In order to provide wiping of each set of nozzles, some dual head printing systems provide one wiper outside of a printing area. Accordingly, such systems are capable of wiping a first print head and then printing with the first print head while wiping the second print head. It should be noted that due to the slow speed at which wiping must occur, printing by the first print head proceeds much slower than in conventional printing.
Accordingly, what is also needed is a system which provides for simultaneous wiping of two ink jet print heads and which causes minimal printing delays.
SUMMARY OF THE INVENTION
The present invention addresses the foregoing problems by providing a wiping system directly triggered by movement of a carriage containing an ink jet print head. As a result, the present invention provides fast nozzle wiping.
In one aspect, the invention is a printer assembly including a carriage, a slide and a wiper assembly. The carriage is for holding a print head and includes a slide contact. The slide includes a wiper ramp and a carriage contact contactable by the slide contact of the carriage. The wiper assembly includes a base, a post extending from the base, a wiper arm, a wiper latch, a wiper holder, and a wiper blade. The wiper arm is connected to the base such that the wiper arm is raised in a case that the wiper arm ramp moves laterally relative to and while in contact with the wiper arm. The wiper latch is connected to the wiper arm such that the wiper latch latches onto the post extending from the base in a case that the wiper arm is sufficiently raised. The wiper holder is connected to the wiper arm, and the wiper blade is connected to the wiper holder.
By virtue of the foregoing arrangement, the printer assembly can quickly and effectively wipe ink jet nozzles of a print head.
Preferably, the carriage includes a wiper latch contact for unlatching the wiper latch during lateral movement of the carriage. Also, in the preferred embodiment, the printer assembly includes a second wiper assembly, the carriage holds a second print head, and the slide has a second wiper arm ramp.
In another aspect, the invention is a wiper assembly including a base, a post extending from the base, a wiper arm connected to the base, a wiper latch connected to the wiper arm, a wiper holder connected to the wiper arm, and a wiper blade connected to the wiper holder. The wiper latch is connected to the wiper arm such that the wiper latch latches onto the post in a case that the wiper arm is sufficiently raised, thereby holding the wiper blade in a raised position.
Preferably, the wiper arm is pivotally connected to the base, and the wiper latch is pivotally connected to the wiper arm. In addition, a latch spring is connected to the base and to the wiper latch such that the latch spring holds the wiper latch against the post and urges the wiper arm downward.
The foregoing wiper assembly arrangement can be used to quickly and effectively wipe ink jet nozzles of a print head before, during and after printing.
In another aspect, the invention is a method of wiping a print head with a wiper blade. The method includes the steps of moving a carriage laterally in a first direction so as to push a slide, raising a wiper arm using a ramp in the slide, thereby raising the wiper blade, and latching a wiper latch to hold the wiper blade at a raised position. The method also includes the steps of moving the carriage laterally in a second direction opposite to the first direction, wiping the print head with the raised wiper blade as the carriage moves in the second direction, unlatching the wiper latch using the carriage, and lowering the wiper blade.
In the preferred embodiment, in a case that the wiper latch is unlatched, the wiper blade is lowered via a latch spring. In addition, the carriage unlatches the wiper latch by pushing the wiper latch during lateral movement.
In a further aspect, the invention is a method of wiping plural print heads with plural wiper blades. The method includes the steps of moving a carriage laterally in a first direction, raising the plural wiper blades, holding the wiper blades at respective raised positions, and wiping each of the print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.
The invention also contemplates a method of wiping plural print heads with plural wiper blades which includes the steps of moving a carriage in a first direction to raise the wiper blades, and wiping each of the plural print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.
In still another aspect, the invention is a method of wiping plural print heads with plural wiper blades. The method includes the steps of moving a carriage laterally in a first direction so as to push a slide, raise plural wiper arms using plural ramps in the slide, thereby raising the plural wiper blades, and latching plural wiper latches to hold the wiper blades at respective raised positions. The method also includes the steps of moving the carriage laterally in a second direction opposite to the first direction, wiping each of the print heads with respective ones of the raised wiper blades as the carriage moves in the second direction, unlatching the wiper latches using the carriage, and lowering the wiper blades.
In the preferred embodiment, when the wiper latches are unlatched, the wiper blades are lowered via latch springs. In addition, the carriage unlatches the wiper latches by pushing the wiper latches.
In yet another aspect, the invention is a method of wiping plural print heads with plural wiper blades. The method includes the step of determining if a predetermined time has elapsed since a last wiping. The method also includes the steps of moving a carriage laterally in a first direction to raise the wiper blades in a case that the predetermined time has elapsed since the last wiping, and wiping each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.
The invention also concerns a method of wiping plural print heads with plural wiper blades including the step of determining if one of plural counters, each of which counts a quantity of ink ejection, has counted to a threshold value. The method also includes the steps of moving a carriage in a first direction to raise the wiper blades in a case that one of the counters has counted to the threshold value, and wiping each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.
In another aspect, the invention is a method of wiping plural print heads with plural wiper blades. The method includes the steps of determining if a predetermined time has elapsed since a last wiping and determining if one of plural counters, each of which counts a quantity of ink ejection, has counted to a threshold value. The method also includes the steps of moving a carriage laterally in a first direction to raise the wiper blades in a case that the predetermined time has elapsed since the last wiping and in a case that one of the counters has counted to the threshold value, and wiping each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.
Advantageously, the foregoing methods provide quick and effective wiping of ink jet nozzles of a print head and thereby increase printing speed.
This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiments thereof in connection with the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
shows a perspective view of computing equipment used in connection with a printer assembly according to the invention.
FIG. 2
is a front, cut-away perspective view of the printer shown in FIG.
1
.
FIG. 3
is a block diagram showing the hardware configuration of a host processor interfaced to a printer having a printer assembly according to the invention.
FIG. 4
is a perspective view of the bottom and rear of a carriage according to the invention.
FIG. 5
, comprising
FIGS. 5A through 5C
, are views of a slide according to the invention.
FIG. 6
, comprising
FIGS. 6A through 6C
, are views of a wiper assembly according to the invention, in a wiper down position.
FIG. 7
, comprising
FIGS. 7A through 7C
, are views of a wiper assembly according to the invention, in a wiper up position.
FIG. 8
is an exploded view of a wiper assembly according to the invention.
FIG. 9
is a flowchart for describing wiping of plural print heads according to the invention.
FIG. 10
is a flowchart for describing a process to wipe plural print heads according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1
is a view showing the outward appearance of computing equipment using connection with the invention described herein. Computing equipment
1
includes host processor
2
. Host processor
2
comprises a personal computer (herein after “PC”), preferably an IBM PC-compatible computer having a windowing environment, such as Microsoft® Windows 95. Provided with computing equipment
1
are display screen
3
comprising a color monitor or the like, keyboard
6
for entering text data and user commands, and pointing device
7
. Pointing device
7
preferably comprises a mouse for pointing to and for manipulating objects displayed on display screen
3
.
Computing equipment 1 includes a computer-readable memory medium, such as fixed computer disk
5
, and floppy disk interface
4
. Floppy disk interface
4
provides a means whereby computing equipment
1
can access information, such as data files, application programs, etc., stored on floppy disks. A similar CD-ROM interface (not shown) may be provided with computing equipment
1
through which computing equipment
1
can access information stored on a CD-ROM.
Disk
5
stores, among other things, application programs by which host processor
2
generates files, manipulates and stores those files on disk
5
, presents data in those files to an operator via display screen
3
, and prints data in those files via printer
10
. Disk
5
also stores an operating system which, as noted above, is preferably a windowing operating system. Device drivers are also stored on disk
5
. At least one of the device drivers comprises a printer driver which provides a software interface to firmware in printer
10
.
In preferred embodiments of the invention, printer
10
is a multi-head serial printer. Accordingly, although the invention described herein is not limited to use with such a printer, the invention will be described in the context of such a printer.
In this regard,
FIG. 2
is a front, cut-away perspective view of printer
10
. As shown in
FIG. 2
, printer
10
is a dual-cartridge printer which prints images using two print heads (i.e., one head per cartridge). Each print head has multiple ink jet nozzles which are used to print data upon a recording medium.
In more detail, cartridges
14
a
and
14
b
each contain a print head and are held in receptacles
12
a
and
12
b
, respectively. Receptacles
12
a
and
12
b
in turn are parts of carriage
11
. Carriage
11
is pulled laterally along bar
16
by belt
17
, which is driven by a carriage motor (not shown). As carriage
11
moves, the ink jet nozzles of the print heads are commanded to eject ink droplets in accordance with print data. Carriage
11
can move both left to right and right to left, providing for dual-directional printing as needed.
Over time, the ink jet nozzles tend to clog. Therefore, the nozzles require intermittent cleaning, such as by the wiping system of the invention.
In response to commands from host processor
2
or commands from internal printer control logic, carriage
11
is moved toward home side
19
of printer
10
, to home position
20
. Carriage
11
is moved to home position
20
, for example, when printer
10
is idle, when printer
10
is turned off, when paper is being ejected from printer
10
, or when the print heads of cartridges
14
a
and
14
b
need to be cleaned.
Disposed at home position
20
so as to clean the print heads are ink suction devices
21
a
and
21
b
, wiper assemblies
22
a
and
22
b
, and ink expulsion receptacles
23
a
and
23
b.
Ink suction devices
21
a
and
21
b
preferably comprise a rotary pump and print head connection caps. The print head connection caps connect to the print heads of cartridges
14
a
and
14
b
during print head cleaning and at other times, such as when printer
10
is powered off, so as to protect the print heads.
Ink expulsion receptacles
23
a
and
23
b
preferably receive ink optionally expelled from the print heads after the print heads are wiped.
Also shown in
FIG. 2
are wiper blades
25
a
and
25
b
and latches
26
a
and
26
b
of wiper assemblies
22
a
and
22
b
. Additionally, slide
28
is shown having carriage contact
29
, which interacts with wiper assemblies
22
a
and
22
b
and carriage
11
during print head wiping operations, as described in more detail below.
FIG. 3
is a block diagram showing the internal functional structure of host processor
2
and printer
10
. In
FIG. 3
, host processor
2
includes a central processing unit
100
such as a programmable microprocessor interfaced to computer bus
101
. Also coupled to computer bus
101
are display interface
102
for interfacing to display
3
, printer interface
104
for interfacing to printer
10
through bi-directional communication line
106
, floppy disk interface
4
for interfacing to floppy disk
107
, keyboard interface
109
for interfacing to keyboard
6
, and pointing device interface
110
for interfacing to pointing device
7
. Disk
5
includes an operating system section for storing operating system
111
, an applications section for storing application files
112
, and a printer driver section for storing printer driver
114
.
A random access main memory (hereinafter “RAM”)
116
interfaces to computer bus
101
to provide CPU
100
with access to memory storage. In particular, when executing stored computer-executable process steps such as those associated with application files
112
, CPU
100
loads those application instruction sequences from disk
5
(or other storage media such as media accessed via a network or floppy disk interface
4
) into RAM
116
and executes those stored program instruction sequences out of RAM
116
. RAM
116
provides for a print data buffer used by printer driver
114
. It should also be recognized that standard disk-swapping techniques available under the windowing operating system allow segments of memory, including the aforementioned print data buffer, to be swapped on and off of disk
5
.
Read only memory (hereinafter “ROM”)
103
in host processor
2
stores invariant instruction sequences, such as start-up instruction sequences or basic input/output operating system (BIOS) sequences for operation of keyboard
6
.
As shown in
FIG. 3
, and as previously mentioned, disk
5
stores program instruction sequences for a windowing operating system and for various application programs such as graphics application programs, drawing application programs, desktop publishing application programs, and the like. In addition, disk
5
also stores color image files such as might be displayed by display
3
or printed by printer
10
under control of a designated application program. Disk
5
also stores a color monitor driver in other drivers section
119
which controls how multi-level RGB color primary values are provided to display interface
102
. Printer driver
114
controls printer
10
for both black/white and color printing and supplies print data for printout according to the configuration of printer
10
. Print data is transferred to printer
10
, and control signals are exchanged between host processor
2
and printer
10
, through printer interface
104
connected to line
106
under control of printer driver
114
. Other device drivers are also stored on disk
5
for providing appropriate signals to various devices, such as network devices, facsimile devices, and the like, connected to host processor
2
.
Printer
10
includes CPU
121
such as an 8-bit or a 16-bit microprocessor, ROM
122
, control logic
124
, and I/O ports unit
127
connected to bus
126
. Also connected to control logic
124
is RAM
129
. Control logic
124
includes controllers for line feed motor
131
, for carriage motor
132
, for print image buffer storage in RAM
129
, for heat pulse generation, and for print head data. Control logic
124
also provides control signals and print data for print heads
15
a
and
15
b
of print engine
130
.
I/O ports unit
127
is coupled to print engine
130
. In print engine
130
, print heads
15
a
and
15
b
perform recording on a recording medium by scanning across the recording medium while printing using print data from a print buffer in RAM
129
. Control logic
124
is also coupled to printer interface
104
of host processor
2
via communication line
106
for exchange of control signals and to receive print data and print data addresses. ROM
122
stores font data, program instruction sequences used to control printer
10
, and other invariant data for printer operation. RAM
129
stores print data in a print buffer defined by printer driver
114
and other information for printer operation.
Although
FIG. 3
shows individual components of printer
10
as separate and distinct from one another, it ig preferable that some of the components be combined. For example, control logic
124
may be combined with I/O ports
127
in an ASIC to simplify interconnections for the functions of printer
10
.
The structure and operation of printer
10
used for cleaning print heads is described below.
Briefly, a printer assembly according to the invention includes a carriage, a slide, and a wiper assembly. The carriage is for holding a print head and includes a slide contact. The slide includes a wiper ramp and a carriage contact contactable by the slide contact of the carriage. The wiper assembly includes a base, a post extending from the base, a wiper arm, a wiper latch, a wiper holder, and a wiper blade. The wiper arm is connected to the base such that the wiper arm is raised in a case that the wiper arm ramp moves laterally relative to and while in contact with the wiper arm. The wiper latch is connected to the wiper arm such that the wiper latch latches onto the post in a case that the wiper arm is sufficiently raised. The wiper holder is connected to the wiper arm, and the wiper blade is connected to the wiper holder. In the preferred embodiment described below, the printer assembly includes a second wiper assembly, the carriage holds a second print head and the slide has a second wiper arm ramp.
FIG. 4
is a perspective view of the bottom and rear of a carriage according to the invention. Due to the orientation of
FIG. 4
, home side
19
is located to the left of the figure.
Carriage
11
has two receptacles
12
a
and
12
b
for holding cartridges
14
a
and
14
b
. At the bottom of cartridges
14
a
and
14
b
are print heads
15
a
and
15
b
. cartridges
14
a
and
14
b
can be removed from receptacles
12
a
and
12
b
for replacement or repair.
Disposed near the bottom of carriage
11
is slide contact
31
. This contact is preferably a small protrusion extending from the rear of carriage
11
. In the preferred embodiment, slide contact
31
is near the side of carriage
11
that is closest to home side
19
. As carriage
11
moves towards home position
20
, slide contact
31
of carriage
11
encounters and pushes carriage contact
29
of slide
28
.
Ledges
32
a
and
32
b
are disposed on the bottom of carriage
11
, one corresponding to each of print heads
15
a
and
15
b
. The ledges are disposed near to the rear of carriage
11
, parallel to the direction of carriage movement and substantially adjacent to print heads
15
a
and
15
b
. Each of ledges
32
a
and
32
b
serves to push against a wiper assembly spacer, discussed below, so as to ensure that only desired portions of wiper blades
25
a
and
25
b
encounter print heads
15
a
and
15
b.
Wiper latch grooves
34
a
and
34
b
are also disposed near the rear of carriage
11
and parallel to the direction of carriage movement on the bottom of carriage
11
. Wiper latch grooves
34
a
and
34
b
provide clearance for wiper latches
26
a
and
26
b
of the wiper assemblies, discussed below, so as to allow carriage
11
to move relative to wiper latches
26
a
and
26
b
for some distance without causing latches
26
a
and
26
b
to unlatch.
Wiper latch contacts
35
a
and
35
b
are disposed at the ends of grooves
34
a
and
34
b
, respectively, which are closest to home side
19
. Contacts
35
a
and
35
b
close off wiper latch grooves
34
a
and
34
b
. Wiper latch contacts
35
a
and
35
b
push and thereby unlatch latched wiper latches
26
a
and
26
b
in a manner discussed below.
FIGS. 5A through 5C
are views of a slide according to the invention.
FIG. 5A
is a front view,
FIG. 5B
is a top view and
FIG. 5C
is an end view of the slide.
Slide
28
is disposed near home position
20
in printer
10
. Support posts
39
extend from the top of slide
28
. Surmounting support posts
39
are support ledges
40
, which sit on top of an interior surface (not shown) in printer
10
. The remainder of slide
28
hangs below the interior surface. A slot in the surface accommodates support posts
39
, allowing the slide to move laterally within printer
10
.
Extending from support ledge
40
that is closest to home side
19
is carriage contact
29
. As mentioned above, when carriage
11
moves towards home position
20
, slide contact
31
of carriage
11
encounters and pushes carriage contact
29
of slide
28
, thereby urging slide
28
in the direction of home side
19
.
Spring post
41
extends from the rear of slide
28
. Spring post
41
is connected to slide spring
42
, which extends away from home side
19
so as to resist motion of slide
28
as slide
28
is pushed by slide contact
31
of carriage
11
toward home side
19
.
Wiper arm ramps
43
a
and
43
b
, corresponding to print heads
15
a
and
15
b
, respectively, are disposed on the front of slide
28
. Each wiper arm ramp slopes upward such that as slide
28
moves laterally toward home side
19
of printer
10
, wiper arms (shown in
FIGS. 6A
to
6
C,
7
A to
7
C, and
8
) which are in contact with wiper arm ramps
43
a
and
43
b
are urged upward. Thus, slide
28
serves to translate the lateral movement of carriage
11
toward home position
20
into an upward movement of wiper arms contacting slide
28
at wiper arm ramps
43
a
and
43
b.
The structure of wiper assembly
22
a
is discussed below. Briefly, a wiper assembly according to the invention includes a base, a post extending from the base, a wiper arm connected to the base, a wiper latch connected to the wiper arm such that the wiper latch latches onto the post extending from the base in a case that the wiper arm is sufficiently raised, a wiper holder connected to the wiper arm, and a wiper blade connected to the wiper holder, such that the wiper blade is raised to a raised position in a case that the wiper arm is raised.
Preferably, the wiper arm is pivotally connected to the base, and the wiper latch is pivotally connected to the wiper arm. Additionally, in the preferred embodiment, the wiper assembly includes a latch spring and a blade spring. The latch spring is connected to the base and to the wiper latch such that the latch spring holds the wiper latch against the post and urges the wiper arm downward. The wiper holder is connected to the wiper arm via the blade spring. Also, the wiper holder preferably includes a wiper spacer that extends past the top of the wiper blade.
In this regard,
FIGS. 6A
to
6
C show wiper assembly
22
a
in a wiper-down position and including wiper blade
25
a
and latch
26
a
of FIG.
2
.
FIG. 6A
is a front view,
FIG. 6B
is a top view, and
FIG. 6C
is an end view of wiper assembly
22
a
in the wiper-down position. It should be noted that a second, substantially similar wiper assembly is provided in printer
10
and includes wiper blade
25
b
and latch
26
b
of FIG.
2
.
Wiper assembly
22
a
includes wiper base
47
. Wiper base
47
has three protrusions extending vertically therefrom. Two of these protrusions are supports
48
and
49
, which hold wiper assembly
22
a
in printer
10
. The third protrusion is post
50
, which is disposed between supports
48
and
49
. In the preferred embodiment, base
47
also includes ink expulsion receptacle
23
a
. As shown, ink expulsion receptacle
23
a
is a hollow rectangular passage through base
47
. In addition, in the preferred embodiment, base
47
is made from a suitable material such as plastic.
Wiper assembly
22
a
also includes wiper arm
53
, which extends from inside of support
48
, across wiper assembly
22
a
and past support
49
. Wiper arm
53
includes tab
60
extending therefrom which, when wiper assembly
22
a
is positioned in printer
10
, rests on wiper arm ramp
43
a
of slide
28
. Thus, when slide
28
moves laterally toward home side
19
of printer
10
, tab
60
extending from wiper arm
53
is urged upward by wiper arm ramp
43
a
. Wiper arm
53
is connected to wiper base
47
such that wiper arm
53
is raised in response to the upward motion of tab
60
.
In the preferred embodiment, wiper arm
53
is pivotally connected to wiper base
47
at wiper arm pivot
54
via arms
55
. Thus, wiper arm
53
is not raised in a linear manner when tab
60
of wiper arm
53
is urged upward by wiper arm ramp
43
a
. Instead, wiper arm
53
rotates around wiper arm pivot
54
, which is positioned such that the resulting motion of wiper arm
53
is generally upward.
Wiper latch
26
a
is connected to wiper arm
53
such that wiper latch
26
a
latches onto post
50
in a case that wiper arm
53
is sufficiently raised. Overhang
61
extends from the top of wiper latch
26
a
. In the preferred embodiment, latch spring
56
is disposed go as to hold wiper latch
26
a
against post
50
and to hold wiper latch
26
a
onto the top of post
50
once wiper latch
26
a
is latched to post
50
. Thus, as wiper arm
53
is raised, wiper latch
26
a
is pressed against post
50
by latch spring
56
. Once overhang
61
of wiper latch
26
a
moves vertically past post
50
, overhang
61
is urged onto the top of post
50
by latch spring
56
, thereby latching wiper latch
26
a
onto post
50
. If wiper latch
26
a
latches onto post
50
, wiper arm
53
remains raised even if no longer urged upward.
In the preferred embodiment, latch spring
56
also urges latch
26
a
downward. In this regard, wiper latch
26
a
preferably is pivotally connected to wiper arm
53
at wiper latch pivot
57
. Thus, latch spring
56
also urges wiper arm
53
downward. Accordingly, once wiper latch
26
a
is unlatched from post
50
, latch spring
56
lowers wiper arm
53
.
Wiper assembly
22
a
also includes wiper holder
58
connected to wiper arm
53
by blade spring
62
. Wiper holder
58
is preferably pivotally connected to wiper base
47
at wiper arm pivots
54
via arms
59
. Thug, wiper holder
56
moves concentrically with wiper arm
53
such that if wiper arm
53
is raised, wiper holder
58
is also raised.
Wiper blade
25
a
is attached to wiper holder
58
. Accordingly, when wiper holder
58
is raised, wiper blade
25
a
is also raised. Therefore, when wiper arm
53
is raised, wiper blade
25
a
is raised.
Wiper blade
25
a
is preferably made from a material suitable for wiping a print head. As print heads are typically somewhat delicate, a soft rubber or plastic is suitable for use as wiper blade
25
a.
Wiper spacer
64
extends vertically from wiper holder
58
past the top of wiper blade
25
a
. Wiper spacer
64
functions in conjunction with ledge
32
a
of carriage
11
so as to ensure that only a desired portion of wiper blade
25
a
comes into contact with print head
15
a
during wiping.
It should be noted that the portion of wiper blade
25
a
that contacts print head
15
a
during wiping is determined by the physical interrelationship of ledge
32
a
, wiper blade
25
a
, and spacer
64
. Accordingly, ledge
32
a
, wiper blade
25
a
, and spacer
64
should be configured so that the exposed surfaces of ink jet nozzles of print head
15
a
are wiped using at least the top edge of wiper blade
25
a.
FIGS. 7A
to
7
C show wiper assembly
22
a
according to the invention, in a wiper-up position.
FIG. 7A
is a front view,
FIG. 7B
is a top view, and
FIG. 7C
is an end view of wiper assembly
22
a
in the wiper-up position.
In order to achieve the wiper-up position according to the invention, wiper arm
53
is raised by wiper arm ramp
43
a
, thereby raising wiper latch
26
a
until overhang
61
latches onto post
50
. Wiper arm
53
also raises wiper holder
58
, which raises wiper blade
25
a
. Because wiper latch
26
a
is latched onto post
50
, wiper arm
53
and thus wiper holder
58
and wiper blade
25
a
remain in the wiper-up position until wiper latch
26
a
is unlatched from post
50
. Wiper latch
26
a
can be unlatched from post
50
by being pushed such that overhang
61
of wiper latch
26
a
is no longer over the top of post
50
. In the preferred embodiment, wiper latch contact
35
a
of carriage
11
pushes wiper latch
26
a
after carriage
11
moves print head
15
a
past raised wiper blade
15
a.
In order to more clearly illustrate a wiper assembly according to the invention,
FIG. 8
shows an exploded view of wiper assembly
22
a
of
FIGS. 6 and 7
. Illustrated in
FIG. 8
is wiper base
47
, wiper arm
53
, wiper latch
26
a
, wiper holder
58
, and wiper blade
25
a
. Wiper base
47
is shown having ink expulsion receptacle
23
a
, supports
48
and
49
, and post
50
. Wiper arm
53
is also shown having tab
60
, arms
55
, wiper arm pivots
54
, and wiper latch pivot
57
. Moreover, wiper latch
26
a
is shown having overhang
61
and wiper holder
58
is shown having wiper blade
25
a
, arms
59
and wiper spacer
64
. Also shown are latch spring
56
and blade spring
62
.
In operation, in a case that one or both of print heads
15
a
and
15
b
in carriage
11
needs to be cleaned, carriage motor
132
drives belt
17
so as to move carriage
11
to home position
20
. As carriage
11
moves into home position
20
, wiper blades
25
a
and
25
b
of wiper assemblies
22
a
and
22
b
are raised to the wiper-up position, as discussed in more detail below. When carriage
11
reaches home position
20
, ink suction devices
21
a
and
21
b
optionally suction ink from print heads
15
a
and
15
b
so as to clear the nozzles of print heads
15
a
and
15
b
. Next, the carriage motor is actuated so as to move carriage
11
from home position
20
, away from home side
19
of printer
10
. As carriage
11
moves, print heads
15
a
and
15
b
pass across raised wiper blades
25
a
and
25
b
, respectively. Wiper blades
25
a
and
25
b
wipe excess ink from print heads
15
a
and
15
b
. After print heads
15
a
and
15
b
have been wiped, wiper blades
25
a
and
25
b
are lowered, as discussed below in more detail.
The operation of the wiper assemblies in raising the wiper blades, wiping the print heads, and lowering the wiper blades is discussed in more detail below with respect to FIG.
9
.
Briefly, such an operation includes the steps of moving a carriage laterally in a fixed direction so a to push a slide, raising plural wiper arms using plural ramps in the slide, thereby raising the wiper blades, and latching plural wiper latches to hold the wiper blades at respective raised positions. The method also includes the steps of moving the carriage laterally in a second direction opposite to the first direction, wiping each of the print heads with a respective one of the raised wiper blades as the carriage moves in the second direction, unlatching the wiper latches using the carriage, and lowering the wiper blades.
It should be noted that in the following discussion, a letter “a” appended to a reference numeral indicates an element associated with wiper assembly
22
a
, and a letter “b” appended to a reference numeral indicates an element associated with wiper assembly
22
b
. The reference numerals themselves correspond to the reference numerals in the above discussion of
FIGS. 6
,
7
and
8
. For example, wiper holders
58
a
and
58
b
have the same construction and function as wiper holder
58
discussed above and correspond respectively to wiper assemblies
22
a
and
22
b.
In step S
901
, carriage
11
moves laterally in a first direction towards home position
20
. As carriage
11
moves, slide contact
31
of carriage
11
comes into contact with carriage contact
29
of slide
28
, thereby pushing slide
28
toward home side
19
of printer
10
.
In step S
902
, wiper arm ramps
43
a
and
43
b
raise wiper arms
53
a
and
53
b
, respectively. As described above, the raising of wiper arms
53
a
and
53
b
raises wiper holders
58
a
and
58
b
, as well as wiper blades
25
a
and
25
b.
Ramps
43
a
and
43
b
are preferably disposed with respect to wiper arms
53
a
and
53
b
such that a wiper blade is raised after being passed over by print heads having a home position closer to home side
19
than the wiper blade. For example, in the preferred embodiment, wiper blade
25
a
is not raised until print head
15
b
has passed over wiper blade
25
a.
In step S
903
, wiper latches
26
a
and
26
b
, which also raise in response to the raising of wiper arms
53
a
and
53
b
, latch onto posts
50
a
and
50
b
using overhangs
61
a
and
61
b
and wiper latch springs
56
a
and
56
b.
In step S
904
, carriage
11
moves laterally away from home position
20
. Therefore, carriage
11
moves in step S
904
in a direction opposite to the direction in which carriage
11
moved in step S
901
.
In step S
905
, as carriage
11
moves away from home position
20
, print heads
15
a
and
15
b
are wiped by wiper blades
25
a
and
25
b
, respectively. Wiping in step S
905
preferably occurs simultaneously so as to shorten an amount of time needed to perform wiping. As each of print heads
15
a
and
15
b
passes its respective wiper blade
25
a
and
25
b
, ledges
32
a
and
32
b
of carriage
11
come into contact with spacers
64
a
and
64
b
, respectively. During this contact, wiper holders
58
a
and
58
b
and spacers
64
a
and
64
b
are urged upward by blade springs
62
a
and
62
b
, respectively, thereby pressing spacers
64
a
and
64
b
against ledges
32
a
and
32
b
, respectively. The urging of wiper holders
58
a
and
58
b
ensures firm contact between wiper blades
25
a
and
25
b
and print heads
15
a
and
15
b
, respectively. Simultaneously, contact between ledges
32
a
and
32
b
and spacers
64
a
and
64
b
ensures that only desired portions of wiper blades
25
a
and
25
b
come into contact with print heads
15
a
and
15
b
, respectively.
During step S
905
, wiper latches
26
a
and
26
b
are latched so as to keep wiper blades
25
a
and
25
b
in raised positions. In order to prevent carriage
11
from unlatching wiper latches
26
a
and
26
b
, wiper latches
26
a
and
26
b
move within wiper latch grooves
34
a
and
34
b
, respectively.
In step S
906
, carriage
11
unlatches wiper latches
26
a
and
26
b
. In step S
906
, respective ones of wiper latch contacts
35
a
and
35
b
contact wiper latches
26
a
and
26
b
after wiper latches
26
a
and
26
b
have moved through wiper latch grooves
34
a
and
34
b
, respectively. Accordingly, wiper latch contact
35
a
pushes wiper latch
26
a
off of post
50
a
, and wiper latch contact
35
b
pushes wiper latch
26
b
off of post
50
b
. Advantageously, wiper latch contact
35
a
unlatches wiper latch
26
a
before print head
15
b
passes wiper blade
25
a
. Accordingly, print head
15
b
is wiped only by wiper blade
25
b.
In step S
907
, wiper blades
25
a
and
25
b
are lowered in response to the unlatching of wiper latches
26
a
and
26
b
. In the preferred embodiment, wiper blades
25
a
and
25
b
are lowered by the urging of wiper arms
53
a
and
53
b
downward by latch springs
56
a
and
56
b.
By virtue of the foregoing structure and operation, plural print heads can be simultaneously, quickly and effectively wiped.
FIG. 10
is a flowchart for describing computer-executable process steps to wipe plural print heads according to the invention. The process steps are preferably embodied in printer driver
114
stored on disk
5
and executed by CPU
100
. Of course, the process steps may be obtained from a source other than printer driver
114
and may also be executed by CPU
121
or by both CPU
100
and CPU
121
.
Briefly, the process steps include a step to determine if a predetermined time has elapsed since a last wiping and to determine if one of plural counters, each of which counts a quantity of ink ejection, has counted to a threshold value. The process steps also include a step to move a carriage laterally in a first direction to raise wiper blades in a case that the predetermined time has elapsed since the last wiping or in a case that one of the counters has counted to the threshold value, and a step to wipe each of the print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.
In more detail, the above steps may use a timer and a counter or counters. Such a timer or counter(s) may be located in host processor
2
or printer
10
. Alternatively, a general purpose timer or counter(s), such as circuitry found in CPU
100
, may also be used. Preferably, the timer and counter(s) are part of control logic
124
or are emulated in software executed by CPU
100
.
Referring to
FIG. 10
, step S
1001
is reached once printing begins. In step S
1001
, it is determined if a predetermined threshold time has elapsed since a last wiping operation. In the preferred embodiment, a timer measures the elapsed time since the last wiping operation by resetting after each wiping operation. If the timer indicates that the threshold time has elapsed, flow proceeds to step S
1003
; if not, flow proceeds to step S
1002
.
In step S
1002
, it is determined if a droplet counter has counted to a predetermined threshold value. Similarly to the above-described timer, a droplet counter counts an amount of ink ejection since a last wiping by resetting after each wiping. If a droplet counter has counted to the threshold value, flow proceeds to step S
1003
; if not, flow returns to step S
1001
.
In the preferred embodiment, plural droplet counters are used, one for each of print heads
15
a
and
15
b
. In this case, each droplet counter counts the number of ink droplets ejected from the corresponding print head since a last wiping. Alternatively, a single counter can be used to count the total number of ink droplets ejected from all print heads. In the alternative case, the predetermined threshold value will likely be approximately twice the value of values used in the preferred embodiment.
The thresholds used in steps S
1001
and S
1002
can be fixed for use with any type of print head. For example, the threshold time can be fixed at sixty seconds, and the threshold value can be fixed at 6 million droplets. However, in preferred embodiments, the thresholds depend on the type of print heads used during printing. Table I shows some examples of Canon™ ink jet print heads and their corresponding threshold values.
TABLE I
|
|
Examples of Droplet and Time Thresholds
|
Threshold
Threshold
|
Print Head
Nozzle
Value
Time
|
|
BC-21,
Black
6 million
60 seconds
|
BC-22,
|
BC-21e, or
Color
1.5 million
60 seconds
|
BC-22e
|
BC-20 or
Black
25 million
60 seconds
|
BC-23
|
|
Although all threshold times are equal in Table I, this need not be the case. Preferably, if two print heads are used, each corresponding to different threshold times, the shorter threshold time is used in step S
1001
.
It should be noted that the order of steps S
1001
and S
1002
can be interchanged. In addition, in alternative embodiments, only one of steps S
1001
or S
1002
is used to determine whether or not wiping is appropriate. For example, in an alternative embodiment, the occurrence of wiping operations is determined solely by a droplet counter.
In step S
1003
, a print head wiping operation is performed. This wiping operation preferably proceeds as explained above with respect to
FIGS. 1
to
9
. After wiping, flow proceeds to step S
1004
, where the timer and the counter(s) are reset. Flow then returns to step S
1001
.
By virtue of the above operation, the invention provides wiping of plural print heads at appropriate moments during printing.
While the present invention is described above with respect to what is currently considered its preferred embodiments, it is to be understood that the invention is not limited to that described above. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims
- 1. A printer assembly comprising:a carriage for holding a print head, the carriage including a slide contact; a slide including a wiper arm ramp and a carriage contact contactable by the slide contact of the carriage; and a wiper assembly including a base, a post extending from the base, a wiper arm connected to the base such that the wiper arm is raised in a case that the wiper arm ramp moves laterally relative to the wiper arm while in contact with the wiper arm, a wiper latch connected to the wiper arm such that the wiper latch latches onto the post extending from the base in a case that the wiper arm is sufficiently raised, a wiper holder connected to the wiper arm, and a wiper blade connected to the wiper holder.
- 2. The printer assembly of claim 1, wherein the wiper arm is pivotally connected to the base.
- 3. The printer assembly of claim 1, wherein the wiper latch is pivotally connected to the wiper arm.
- 4. The printer assembly of claim 1, wherein the carriage further includes a wiper latch contact for unlatching the wiper latch during lateral movement of the carriage.
- 5. The printer assembly of claim 4, wherein the wiper assembly further includes a latch spring connected to the base and to the wiper latch for holding the wiper latch against the post and for urging the wiper arm downward.
- 6. The printer assembly of claim 1, wherein the wiper assembly further includes a blade spring and wherein the wiper holder is connected to the wiper arm via the blade spring.
- 7. The printer assembly of claim 1, wherein the wiper assembly further includes a wiper spacer connected to the wiper holder such that the wiper spacer extends vertically past the wiper blade.
- 8. The printer assembly of claim 1, further comprising a second wiper assembly, wherein the carriage holds a second print head and the slide has a second wiper arm ramp.
- 9. The printer assembly of claim 1, wherein the base of the wiper assembly includes an ink expulsion receptacle.
- 10. A wiper assembly comprising:a base; a post extending from the base; a wiper arm connected to the base; a wiper latch connected to the wiper arm such that the wiper latch latches onto the post extending from the base in a case that the wiper arm is sufficiently raised; a wiper holder connected to the wiper arm; and a wiper blade connected to the wiper holder, wherein the wiper blade is raised in a case that the wiper arm is raised.
- 11. The wiper assembly of claim 10, wherein the wiper arm is pivotally connected to the base.
- 12. The wiper assembly of claim 10, wherein the wiper latch is pivotally connected to the wiper arm.
- 13. The wiper assembly of claim 10, further comprising a latch spring connected to the base and to the wiper latch such that the latch spring holds the wiper latch against the post and urges the wiper arm downward.
- 14. The wiper assembly of claim 10, further comprising a blade spring, wherein the wiper holder is connected to the wiper arm via the blade spring.
- 15. The wiper assembly of claim 10, wherein the wiper holder further comprises a wiper spacer that extends vertically past the wiper blade.
- 16. The wiper assembly of claim 10, wherein the base further includes an ink expulsion receptacle.
- 17. A method of wiping a print head with a wiper blade, the wiper blade being raisable by a wiper arm of a wiper assembly having a base, comprising the steps of:moving a carriage laterally in a first direction so as to push a slide; raising a wiper arm using a ramp in the slide, thereby raising the wiper blade; latching a wiper latch onto a post extending from the base of the wiper assembly to hold the wiper blade at a raised position; moving the carriage laterally in a second direction opposite to the first direction; wiping the print head with the raised wiper blade as the carriage moves in the second direction; unlatching the wiper latch using the carriage; and lowering the wiper blade.
- 18. The method of claim 17, wherein the wiper arm pivots upward when raised.
- 19. The method of claim 17, wherein the wiper blade is lowered via a latch spring.
- 20. The method of claim 17, wherein the carriage unlatches the wiper latch by pushing the wiper latch.
- 21. A method of wiping plural print heads with plural wiper blades, comprising the steps of:moving a carriage laterally in a first direction so as to push a slide having plural wiper arm ramps; raising the plural wiper blades by raising plural wiper arms using the plural wiper arm ramps; holding the wiper blades at respective raised positions; and wiping each of the print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.
- 22. The method of claim 21, wherein the wiper arms pivot upward when raised.
- 23. The method of claim 21, wherein the wiper blades are held at the respective raised positions via plural wiper latches, and further comprising the step of lowering each wiper blade via a latch spring.
- 24. The method of claim 23, further comprising the step of unlatching the wiper latches by pushing the wiper latches with the carriage.
- 25. A method of wiping plural print heads with plural wiper blades, comprising the steps of:moving a carriage in a first direction to raise the plural wiper blades; latching plural wiper latches onto plural posts, each of the plural posts extending from the base of a respective one of plural wiper assemblies, thereby holding the wiper blades at respective raised positions; and wiping each of the plural print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.
- 26. A method of wiping plural print heads with plural wiper blades, comprising the steps of:determining if one of plural predetermined times has elapsed since a last wiping, each of the predetermined times corresponding to a respective print head, wherein each of the plural predetermined times are concurrently monitored; moving a carriage laterally in a first direction to raise the wiper blades in a case that at least one of the plural predetermined times has elapsed since the last wiping; and wiping each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.
- 27. The method of claim 26, wherein each of the plural predetermined times corresponds to a type of print head.
- 28. A method of wiping plural print heads with plural wiper blades, comprising the steps of:determining if one of plural counters, each of which counts a quantity of ink ejection from a corresponding print head, has counted to a threshold value, wherein each of the plural counters are concurrently monitored; moving a carriage in a first direction to raise the plural wiper blades in a case that one of the counters has counted to the threshold value; wiping each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.
- 29. The method of claim 28, wherein the threshold value depends on the type of print head used during printing.
- 30. A method of wiping plural print heads with plural wiper blades, comprising the steps of:determining if one of plural predetermined times has elapsed since a last wiping, each of the predetermined times corresponding to a respective print head, wherein each of the plural predetermined times are concurrently monitored; determining if one of plural counters, each of which counts a quantity of ink ejection from a corresponding print head, has counted to a threshold value, wherein each of the plural counters are concurrently monitored; moving a carriage laterally in a first direction to raise the wiper blades in a case that at least one of the plural predetermined times has elapsed since the last wiping or in a case that one of the counters has counted to the threshold value; and wiping each of the print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.
- 31. The method of claim 30, wherein each of the plural predetermined times corresponds to a type of print head.
- 32. The method of claim 30, wherein the threshold value depends on the type of print head used during printing.
- 33. A method of wiping plural print heads with plural wiper blades, the wiper blades being respectively raisable by plural wiper arms, each wiper arm being in a respective wiper assembly having a base, comprising the steps of:moving a carriage laterally in a first direction so as to push a slide; raising plural wiper arms using plural ramps in the slide, thereby raising the wiper blades; latching each of plural wiper latches onto a post extending from the base of the respective wiper assembly to hold the wiper blades at respective raised positions; moving the carriage laterally in a second direction opposite to the first direction; wiping each of the print heads with a respective one of the raised wiper blades as the carriage moves in the second direction; unlatching the wiper latches using the carriage; and lowering the wiper blades.
- 34. The method of claim 33, wherein the wiper arms pivot upward when raised.
- 35. The method of claim 33, wherein each wiper blade is lowered via a latch spring.
- 36. The method of claim 33, wherein the carriage unlatches the wiper latches by pushing the wiper latches.
- 37. A computer-readable memory medium storing computer-executable process steps to wipe plural print heads with plural wiper blades, the steps comprising:a determining step to determine if one of plural predetermined times has elapsed since a last wiping, each of the predetermined times corresponding to a respective print head, wherein each of the plural predetermined times are concurrently monitored; a moving step to move a carriage laterally in a first direction to raise the wiper blades in a case that at least one of the plural predetermined times has elapsed since the last wiping; and a wiping step to wipe each of the print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.
- 38. The computer-readable memory medium of claim 37, wherein each of the plural predetermined times corresponds to a type of print head.
- 39. A computer-readable memory medium storing computer-executable process steps to wipe plural print heads with plural wiper blades, the steps comprising:a determining step to determine if one of plural counters, each of which counts a quantity of ink ejection from a corresponding print head, has counted to a threshold value, wherein each of the plural counters are concurrently monitored; a moving step to move a carriage in a first direction to raise the plural wiper blades in a case that one of the counters has counted to the threshold value; and a wiping step to wipe each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.
- 40. The computer-readable memory medium of claim 39, wherein the threshold value depends on the type of print head used during printing.
- 41. A computer-readable memory medium storing computer-executable process steps to wipe plural print heads with plural wiper blades, the steps comprising:a determining step to determine if one of plural predetermined times has elapsed since a last wiping, each of the predetermined times corresponding to a respective print head, wherein each of the plural predetermined times are concurrently monitored; a determining step to determine if one of plural counters, each of which counts a quantity of ink ejection from a corresponding print head, has counted to a threshold value, wherein each of the plural counters are concurrently monitored; a moving step to move a carriage laterally in a first direction to raise the wiper blades in a case that at least one of the plural predetermined times has elapsed since the last wiping or in a case that one of the counters has counted to the threshold value; and a wiping step to wipe each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.
- 42. The computer-readable memory medium of claim 41, wherein each of the plural predetermined times corresponds to a type of print head.
- 43. The computer-readable memory medium of claim 41, wherein the threshold value depends on the type of print head used during printing.
US Referenced Citations (7)
Foreign Referenced Citations (1)
Number |
Date |
Country |
0 698 495 |
Feb 1996 |
EP |