Title: Printing apparatus and printing method
Abstract: In a printing apparatus a printing medium is fed such that before a paper sensor detects a trailing edge of a preceding printing medium, a paper feeding roller begins the feeding of a succeeding printing medium, and after the paper sensor detects the trailing edge of the preceding printing medium, a leading edge of the succeeding printing medium arrives at the location of the paper sensor. Thus, the feeding of printing paper is performed rapidly and consequently the printing apparatus can perform recording rapidly.
Patent Number: 6,978,992 Issued on 12/27/2005 to Otsuka
| Inventors:
|
Otsuka; Naoji (Yokohama, JP)
|
| Assignee:
|
Canon Kabushiki Kaisha (Tokyo, JP)
|
| Appl. No.:
|
733360 |
| Filed:
|
December 12, 2003 |
Foreign Application Priority Data
| Jul 30, 1999[JP] | 11-217218 |
| Current U.S. Class: |
271/10.01; 271/258.01; 271/265.01 |
| Intern'l Class: |
B65H 005/00 |
| Field of Search: |
271/1001,100.2,100.3,258.01,265.01
347/37,104
|
References Cited [Referenced By]
U.S. Patent Documents
| 5223858 | Jun., 1993 | Yokoi et al.
| |
| 5664771 | Sep., 1997 | Nagatani et al.
| |
| 5676363 | Oct., 1997 | Kishida et al.
| |
| 6074055 | Jun., 2000 | Myung.
| |
| 6076821 | Jun., 2000 | Embry et al.
| |
| 6234694 | May., 2001 | Brookner.
| |
| 6290351 | Sep., 2001 | Merz.
| |
| 6497468 | Dec., 2002 | Otsuka.
| |
| 6702274 | Mar., 2004 | Otsuka.
| |
| Foreign Patent Documents |
| 1-288471 | Nov., 1989 | JP.
| |
| 5-286608 | Nov., 1993 | JP.
| |
| 6-156772 | Jun., 1994 | JP.
| |
| 9-197730 | Jul., 1997 | JP.
| |
| 10-35940 | Feb., 1998 | JP.
| |
| 2775767 | May., 1998 | JP.
| |
| 2000/-127367 | May., 2000 | JP.
| |
Primary Examiner: Bollinger; David H.
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper & Scinto
Parent Case Text
This application is a division of application Ser. No. 09/628,022 filed Jul.
28, 2000 now U.S. Pat. No. 6,702,274.
Claims
1. An ink jet printing apparatus for printing on a printing medium with a printing
head for ejecting ink, said apparatus comprising:
feeding means for feeding the printing medium toward the printing head;
conveying means for conveying intermittently the printing medium fed by said
feeding means to a position opposite to the printing head;
scanning means for scanning the printing head in a scanning direction different
from a conveying direction of the printing medium conveyed by said conveying means;
detection means for detecting an edge of the printing medium fed by said feeding
means; and
control means for controlling the driving of said feeding means so as to (1)
cause said feeding means to initiate the feeding of a succeeding printing medium
after said feeding means initiates the feeding of a preceding printing medium and
before said detection means detects a trailing edge of the preceding printing medium
and (2) cause a leading edge of the succeeding printing medium to arrive at said
detection means after said detection means detects the trailing edge of the preceding
printing medium.
2. An ink jet printing apparatus according to claim 1, wherein on the basis of
information specifying the length in the feeding direction of the preceding printing
medium, said feeding means initiates the feeding of the succeeding printing medium.
3. An ink jet printing apparatus according to claim 1, wherein feeding control
by said control means is executed when determined that the feeding of the succeeding
printing medium is necessary during printing on the preceding printing medium.
4. An inkjet printing apparatus according to claim 1, wherein said feeding means
comprises a feed roller for feeding the printing medium from a printing medium
storing unit, and said detection means comprises a single unit set between said
feed roller and the printing head along a conveyance path of the printing medium.
5. An ink jet printing apparatus according to claim 1, wherein said control means
determines whether the leading edge of the succeeding printing medium has been
fed to arrive at a predetermined position upstream of said detection means along
a conveyance path, wherein when the leading edge of the succeeding printing medium
has been fed to arrive at the predetermined position, said control means determines
whether the trailing edge of the preceding printing medium has passed said detection
means, and wherein when the trailing edge of the preceding printing medium has
not passed said detection means, said control means interrupts the feeding of the
succeeding printing medium.
6. An ink jet printing method for printing on a printing medium by scanning a
printing head for ejecting ink, said method comprising the steps of:
feeding a printing medium toward the printing head;
conveying intermittently the printing medium fed in said feeding step to a position
opposite to the printing head;
scanning the printing head in a scanning direction different from a conveying
direction of the printing medium conveyed in said conveying step;
initiating the feeding of a succeeding printing medium toward the printing head
after the feeding of a preceding printing medium is initiated and before a trailing
edge of the preceding printing medium is detected at a predetermined position; and
feeding the succeeding printing medium so that a leading edge of the succeeding
printing medium arrives at the predetermined position after the trailing edge of
the preceding printing medium is detected at the predetermined position.
7. An ink jet printing apparatus for printing on a printing medium with a printing
head for ejecting ink, said apparatus comprising:
feeding means for feeding the printing medium toward the printing head;
conveying means for conveying intermittently the printing medium fed by said
feeding means to a position opposite to the printing head;
scanning means for scanning the printing head in a scanning direction different
from a conveying direction of the printing medium conveyed by said conveying means;
detection means for detecting an edge of the printing medium fed by said feeding
means; and
control means for controlling the driving of said feeding means so as to cause
said feeding means to initiate the feeding of a succeeding printing medium after
said feeding means initiates the feeding of a preceding printing medium and before
said detection means detects a trailing edge of the preceding printing medium,
wherein said control means causes said feeding means to initiate the feeding
of the succeeding printing medium on the basis of information specifying the length
in the feeding direction of the preceding printing medium.
8. An ink jet printing apparatus according to claim 7, wherein feeding control
by said control means is executed when determined that the feeding of the succeeding
printing medium is necessary during printing on the preceding printing medium.
9. An inkjet printing apparatus according to claim 7, wherein said feeding means
comprises a feed roller for feeding the printing medium from a printing medium
storing unit, and said detection means comprises a single unit set between said
feed roller and the printing head along a conveyance path of the printing medium.
10. An ink jet printing apparatus according to claim 7, wherein said control
means comprises calculation means for calculating a position of the trailing edge
of the preceding printing medium on the basis of the information specifying the
length and information on a conveyance amount that the preceding printing medium
has been conveyed by said conveying means after a leading edge of the preceding
printing medium passed said detection means, and causes said feeding means to initiate
the feeding of the succeeding printing medium based on a result of the calculation
by said calculation means.
11. An ink jet printing apparatus according to claim 7, wherein said control
means determines whether a leading edge of the succeeding printing medium has been
fed to arrive at a predetermined position upstream of said detection means along
a conveyance path, wherein when the leading edge of the succeeding printing medium
has been fed to arrive at the predetermined position, said control means determines
whether the trailing edge of the preceding printing medium has passed said detection
means, and wherein when the trailing edge of the preceding printing medium has
not passed said detection means, said control means interrupts the feeding of the
succeeding printing medium.
12. An ink jet printing apparatus for printing on a printing medium with a printing
head for ejecting ink, said apparatus comprising:
feeding means for feeding the printing medium toward the printing head;
conveying means for conveying intermittently the printing medium fed by said
feeding means to a position opposite to the printing head;
scanning means for scanning the printing head in a scanning direction different
from a conveying direction of the printing medium conveyed by said conveying means;
detection means for detecting an edge of the printing medium fed by said feeding
means; and
control means that (1) causes said feeding means to initiate the feeding of a
succeeding printing medium on the basis of information specifying the length in
the feeding direction of a preceding printing medium, after said feeding means
initiates the feeding of the preceding printing medium and before said detection
means detects a trailing edge of the preceding printing medium, and (2) thereby
causes a leading edge of the succeeding printing medium to arrive at said detection
means after said detection means detects the trailing edge of the preceding printing medium.
13. An ink jet printing apparatus according to claim 12, wherein feeding control
by said control means is executed when determined that the feeding of the succeeding
printing medium is necessary during printing on the preceding printing medium.
14. An ink jet printing apparatus according to claim 12, wherein said control
means comprises calculation means for calculating a position of the trailing edge
of the preceding printing medium on the basis of the information specifying the
length and information on a conveyance amount that the preceding printing medium
has been conveyed by said conveying means after a leading edge of the preceding
printing medium passed said detection means, and causes said feeding means to initiate
the feeding of the succeeding printing medium based on a result of the calculation
by said calculation means.
15. A method of feeding a printing medium in an ink jet printing apparatus for
printing on the printing medium with a printing head for ejecting ink, said method
comprising the steps of:
feeding the printing medium toward the printing head;
conveying intermittently the printing medium fed in said feeding step to a position
opposite to the printing head;
scanning the printing head in a scanning direction different from a conveying
direction of the printing medium conveyed in said conveying step;
detecting an edge of the printing medium fed in said feeding step by edge detection
means at a predetermined position; and
controlling a feeding operation in said feeding step so as to (1) cause initiation
of the feeding of a succeeding printing medium after the feeding of a preceding
printing medium is initiated in said feeding step and before a trailing edge of
the preceding printing medium is detected at the predetermined position and (2)
cause a leading edge of the succeeding printing medium to arrive at the predetermined
position after the trailing edge of the preceding printing medium is detected at
the predetermined position.
16. A method according to claim 15, wherein based on information specifying the
length in the feeding direction of the preceding printing medium, the feeding of
the succeeding printing medium is initiated.
17. A method of feeding a printing medium in an ink jet printing apparatus for
printing on the printing medium with a printing head for ejecting ink, said method
comprising the steps of:
feeding the printing medium toward the printing head;
conveying intermittently the printing medium fed in said feeding step to a position
opposite to the printing head;
scanning the printing head in a scanning direction different from a conveying
direction of the printing medium conveyed in said conveying step;
detecting an edge of the printing medium fed in said feeding step at a predetermined
position; and
controlling the feeding operation in said feeding step so as to initiate the
feeding of a succeeding printing medium after the feeding of a preceding printing
medium is initiated in said feeding step and before a trailing edge of the preceding
printing medium is detected at the predetermined position,
wherein in said controlling step the feeding of the succeeding printing medium
is initiated on the basis of information capable of specifying the length in the
feeding direction of the preceding printing medium.
18. A method of feeding a printing medium in an ink jet printing apparatus for
printing on the printing medium with a printing head for ejecting ink, said method
comprising the steps of:
feeding the printing medium toward the printing head;
conveying intermittently the printing medium fed in said feeding step to a position
opposite to the printing head;
scanning the printing head in a scanning direction different from a conveying
direction of the printing medium conveyed in said conveying step;
detecting an edge of the printing medium fed in said feeding step at a predetermined
position; and
executing control so as to (1) initiate the feeding of a succeeding printing
medium in said feeding step based on information specifying the length in the feeding
direction of a preceding printing medium, after the feeding of the preceding printing
medium is initiated in said feeding step and before a trailing edge of the preceding
printing medium is detected at the predetermined position, and (2) thereby cause
a leading edge of the succeeding printing medium to arrive at the predetermined
position after the trailing edge of the preceding printing medium is detected at
the predetermined position.
19. An ink jet printing apparatus for printing on a printing medium with a printing
head for ejecting ink, said apparatus comprising:
feeding means for feeding the printing medium toward the printing head;
conveying means for conveying intermittently the printing medium fed by said
feeding means to a position opposite to the printing head;
scanning means for scanning the printing head in a scanning direction different
from a conveying direction of the printing medium conveyed by said conveying means;
detection means for detecting an edge of the printing medium fed by said feeding
means; and
control means for controlling the driving of said feeding means so as to cause
said feeding means to initiate the feeding of a succeeding printing medium after
said feeding means initiates the feeding of a preceding printing medium and before
said detection means detects a trailing edge of the preceding printing medium.
20. An ink jet printing apparatus according to claim 19, wherein feeding control
by said control means is executed when determined that the feeding of the succeeding
printing medium is necessary during printing on the preceding printing medium.
21. An inkjet printing apparatus according to claim 19, wherein said feeding
means comprises a feed roller for feeding the printing medium from a printing medium
storing unit, and said detection means comprises a single unit set between said
feed roller and the printing head along a conveyance path of the printing medium.
22. An ink jet printing apparatus according to claim 19, wherein said control
means determines whether a leading edge of the succeeding printing medium has been
fed to arrive at a predetermined position upstream of said detection means along
a conveyance path, wherein when the leading edge of the succeeding printing medium
has been fed to arrive at the predetermined position, said control means determines
whether the trailing edge of the preceding printing medium has passed said detection
means, and wherein when the trailing edge of the preceding printing medium has
not passed said detection means, said control means interrupts the feeding of the
succeeding printing medium.
23. A method of feeding a printing medium in an ink jet printing apparatus for
printing on the printing medium with a printing head for ejecting ink, said method
comprising the steps of:
feeding the printing medium toward the printing head;
conveying intermittently the printing medium fed in said feeding step to a position
opposite to the printing head;
scanning the printing head in a scanning direction different from a conveying
direction of the printing medium conveyed in said conveying step;
detecting an edge of the printing medium fed in said feeding step by edge detection
means; and
controlling the feeding operation in said feeding step so as to initiate the
feeding of a succeeding printing medium after the feeding of a preceding printing
medium is initiated in said feeding step and before the edge detection means detects
a trailing edge of the preceding printing medium.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printing apparatus and a printing method,
and relates in particular to a printing apparatus for high-speed paper supply and
a printing method therefor.
2. Related Background Art
In a conventional apparatus, in order to increase printing speeds and to simplify
mechanisms, a paper feeding mechanism, a paper conveying mechanism and a carriage
mechanism are independently driven, or special motors are provided to drive these
mechanisms at optimal timings.
However, the following problem plagues a conventional system, comprising
these mechanisms, that initiates the feeding of a succeding printing medium without
detecting the trailing end of a preceding printing medium. For example, when the
lengths of printing media differ between a predecessor and a successor or when
the lengths of the printing media vary, or when slippage occurs at a paper feeding
mechanism, preceding and succeding media overlap each other, so that in a printing
apparatus that has only one paper sensor a trailing edge of the preceding printing
medium and a leading edge of the succeeding one cannot be discriminated, thereby
causing paper feeding failures.
If the trailing end of the preceding printing medium is detected first and then
the feeding of the succeeding printing medium is started, the above problem can
be avoided. However, unless the sensor for the printing medium is located very
near the feeding mechanism, a satisfactory effect can not be obtained because the
interval between the preceding and succeeding printing media will be extended.
Further, in the printing apparatus, the leading edges of printing media are detected
immediately after the media are fed by a feeding mechanism, so that, if because
of slippage the feeding distance of the printing media varies before they reach
the sub-scanning mechanism, there is no means available to correct such variation.
Therefore, no conventional printing apparatuses can cope with reductions in the
intervals between printing media that are consecutively fed, stabilization in positioning
the leading edges, and differences in the lengths of printing media. For removing
the above-mentioned trouble, it is generally effective to employ two paper sensors,
but such a use results in increased manufacturing costs.
SUMMARY OF THE INVENTION
It is, therefore, one objective of the present invention to provide a printing
apparatus that enables fast printing, by increasing the speed of the paper feeding
operation, and a printing method therefor.
To achieve the above objective, according to one aspect of the invention, a printing
apparatus for printing on a printing medium employing a printing head, comprises:
feeding means for feeding a printing medium toward the printing head;
detection means for detecting an edge of the printing medium fed by the
feeding means; and
control means for controlling the driving of the feeding means so as to (1)
cause the feeding means to initiate the feeding of a succeeding printing medium
after the feeding means initiates the feeding of a preceding printing medium and
before the detection means detects a trailing edge of the preceding printing medium
and (2) cause a leading edge of the succeeding printing medium to arrive at the
detection means after the detection means detects the trailing edge of the preceding
printing medium.
Further, according to another aspect of the invention, a printing method
for printing on a printing medium with a printing head, comprises the steps of:
feeding a printing medium toward the printing head;
initiating the feeding of a succeeding printing medium toward the printing
head, after the feeding of a preceding printing medium is initiated and before
a trailing edge of the preceding printing medium is detected at a predetermined
position; and
feeding the succeeding printing medium so that a leading edge of the preceding
printing medium arrives at the predetermined position after the leading edge of
the preceding printing medium is detected at the predetermined position.
In this specification, "printing" includes not only the formation of meaningful
information, such as characters or figures, on a printing medium, but also includes
the formation of various images, designs and patterns on a printing medium or the
processing employed for the printing medium, whether or not they convey any meanings
or whether or not they can be visually distinguished by humans.
The term "printing medium" refers not only to a paper that is used by a common
printing apparatus, but also to various other types of media, such as cloth, plastic
film and metal plates, that can accept ink.
Further, "ink" should be appreciated broadly as the definition of "printing".
That is, it should be understood as liquid that can be applied onto a printing
medium to form images, designs and patterns, or liquid that can be used to process
the printing medium.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram illustrating the arrangement of an ink-jet printing
apparatus according to one embodiment of the present invention;
FIG. 2 is a specific perspective view of the structure of an essential portion
of a printing head;
FIG. 3 is a schematic block diagram illustrating the arrangement of a controller
circuit in the ink-jet printing apparatus according to the embodiment of the present invention;
FIGS. 4A, 4B, 4C, 4D and 4E are diagrams showing
a conventional consecutive feeding method;
FIGS. 5A, 5B, 5C, 5D and 5E are diagrams showing
a consecutive feeding method according to the present invention;
FIGS. 6A, 6B, 6C, 6D and 6E are diagrams showing
the consecutive feeding method according to the present invention;
FIG. 7 is a flowchart for the control performed for the invention;
FIG. 8 is a flowchart for the control performed for the invention; and
FIG. 9 is a flowchart for the control performed for the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
According to one embodiment of the invention, a printing apparatus, which
includes a fast printing mechanism, determines whether or not paper feeding should
be continued when a leading edge of a succeeding printing medium is immediately
before a paper sensor while a trailing edge of a preceding printing medium passes
through the paper sensor. Therefore, such a system can be provided that enables
the precise feeding of preceding and succeeding printing media, even when the media overlap.
If it is determined that the continuous paper feeding is permitted, the process
is not interrupted, so that compared with a conventional apparatus, which must
start feeding after the determination by the sensor, the printing apparatus of
this invention can feed paper very rapidly. In addition, even when the apparatus
temporarily halts the feeding, it resumes the feeding immediately after detecting
the actual trailing edge of the preceding printing media. Thus, unlike the conventional
art, overlapped paper feeding does not occur. Further, the paper feeding may start
when preceding and succeeding printing media overlap. In this case, since a required
distance between the printing media is maintained immediately before the sensor,
an amount for movement to a cue position is precisely controlled and the minimum
possible real distance is maintained. Furthermore, the paper feeding may start
when the media are separated. In short, the interval between the printing media
and the timing for the paper feeding mechanism can be arbitrarily set. Since during
printing a serial type printing apparatus intermittently feeds a preceding printing
medium in the sub-scanning direction, the paper feeding interval is not constant
unlike the paper feeding mechanism which conducts consecutive paper feeding. However,
as described above, according to the method of the invention an arbitrary interval
is set until the paper reaches the paper sensor, so that for the design, the degree
of freedom increases.
The reduction in the paper feeding and the paper discharge time can most efficiently
increase the throughput in the printing apparatus. For example, for a printing
apparatus having a printing speed of 10 ppm, the average time for printing a sheet
is six seconds. But when the paper feeding time is three seconds per sheet, the
printing itself requires only three seconds.
The paper feeding and discharging is sorted into the three following cases.
1) When the paper feeding is performed to print the first printing medium.
2) When the printing of a preceding printing medium is completed and the
feeding of a succeeding printing medium is begun while the preceding printing medium
is being discharged.
3) When the feeding of a succeeding printing medium is begun while a preceding
printing medium is being printed.
The full paper feeding time is required for the item 1), that is, for the paper
feeding to print on the first printing medium. In this case, the operation having
the highest priority is the paper feeding at maximum speed from an ASF.
In the item 2), the printing of a preceding printing medium is completed and
the
feeding of a succeeding printing medium is begun while discharging the preceding
medium. In this case, the current position of the preceding printing medium is
calculated with executing the driving in the sub-scanning direction to discharge
the preceding printing medium, and the driving for feeding a succeding printing
medium is begun at an optimal position. In this case, the operations having the
highest priority are the prompt completion of the paper discharge, and termination
of the paper feeding when the discharge process has been completed.
For that attainment, the distance between the preceding and succeeding printing
media is minimized, and a printing medium is made controllable at a position, immediately
preceding the paper sensor, so as to cause the paper sensor to accurately detect
a trailing edge of the preceding printing medium and a leading edge of the succeeding
printing medium. Thus, printing can be started at a precise location relative to
the position, in the sub-scanning direction, of the leading edge of the succeeding
printing medium. Especially, in order to obtain a precise cue positioning distance,
it is preferable for the paper sensor to be located as far as possible from the
paper feeding mechanism and relatively near a delivery roller for sub-scanning.
This arrangement is very effective because the paper feeding process can be initiated
regardless of a signal from the paper sensor.
In the item 3), the feeding of a succeeding printing medium is begun while a
preceding
printing medium is being printed. In this case, the current position of the preceding
printing medium is calculated, and the driving for feeding the succeeding printing
medium is begun at the optimal location. In this case, since the printing of the
preceding printing medium is driven continuously, the carriage mechanism must be
driven in addition to the printing by the printing head.
In these cases, three drivings are executed at the same time, that is, in addition
to the paper feeding, the above-mentioned two drivings are executed intermittently.
Therefore, as a method for feeding a succeeding printing medium, the medium
can be intermittently driven in the sub-scanning direction, the preceding and succeeding
printing media can be driven substantially at the same average speed, or the preceding
and succeeding printing media can be delivered to a position immediately preceding
the paper sensor at the same time, while it is permitted that a leading edge of
the succeeding printing and a trailing edge of the preceding printing medium overlap.
With either method, the paper feeding is not started by determination by means
of the paper sensor, but started based on information on the length of the preceding
printing medium or a fixed value. Thus, the feeding of the succeeding printing
medium may be begun from the time when the preceding and succeding printing media
overlap or they are separated with an interval therebetween. Furthermore, since
a distance between the printing media can be used up to the paper sensor located
immediately before the convey roller, the degree of freedom for control is great,
even when the printer is a serial printer that feeds the preceding printing media
intermittently and basically consecutively feeds the succeeding printing medium.
Preferred embodiments of the present invention will now be described in
detail while referring to the accompanying drawings. In the drawings, the same
reference numerals are used to denote respective corresponding or identical components.
(Arrangement
1 of Printing Apparatus)
FIG. 1 is a diagram showing the arrangement of an essential portion of an ink-jet
printing apparatus according to an embodiment of the present invention.
In FIG. 1, a head cartridge (or head cartridges)
1 is positionally and
exchangeably mounted on a carriage
2. The head cartridge
1 includes
a printing head and an ink tank, and further comprises a connector (not shown)
for receiving/sending various signals such as a printing head driving signal.
A connector holder (electrical connector) is provided in the carriage
2
to transmit the drive signal and others to the head cartridge
1 therethrough.
The carriage
2 is supported by a guide shaft
3, which is provided
in a main body of the apparatus and which is extended in the main scanning direction,
along which the carriage
2 reciprocates. The carriage
2 is driven
by a main scan motor
4 via a drive mechanism that is constituted by a motor
pulley
5, a coupled pulley
6, a timing belt
7, etc. and its
position and movement are controlled. Further, a home position sensor
30
is provided on the carriage
2. The location of the carriage
2 is
detected when it passes a shielding plate
36.
As a pickup roller
31 is rotated, via drive gears, by a feed motor
35,
printing media
8, such as a printing sheet or a thin plastic plate, are
separately fed, one by one, from an auto sheet feeder (hereinafter referred to
as an ASF)
32. Further, as a conveyer roller
9 is rotated, the printing
medium
8 is conveyed (or sub-scanned) passing through a position (a printing
unit) opposite to a discharge port face of the head cartridge
1. The conveyer
roller
9 is driven, via the drive gears, by the rotation of an LF (line
feed) motor
34. At this time, the discrimination as to whether a printing
medium has been fed, and the determination of the cue position of the printing
medium
8 are done at the time the feeding is done when the printing medium
8 passes through a paper end sensor
33. The paper end sensor
33
is also employed to acquire an actual location of a trailing edge of the printing
medium
8 and to calculate the current printing location based on the actual
trailing edge position. It is noted that a back side of the printing medium
8
is supported by a platen (not shown) in order to provide a flat printing surface
at the printing unit. In this case, each head cartridge
1 mounted on the
carriage
2 is supported so that the faces of the discharging portions protrude
downward from the carriage
2, and are parallel to the printing medium
8
between the two sets of rollers. The head cartridge
1 is an ink-jet head
cartridge that employs thermal energy to eject ink and includes electro-thermal
converting elements for generating the thermal energy. That is, bubbles are generated
by film boiling induced by the thermal energy that is applied by the electro-thermal
converting elements, and the printing head of the head cartridge
1 employs
the pressure exerted by the air bubbles to eject ink through the discharging orifices
for printing.
FIG. 2 is a specific, partial perspective view of the structure of an essential
portion of the printing head of a head cartridge
1.
In FIG. 2, a plurality of discharging orifices
22 are formed at a predetermined
pitch on a surface of a discharging portion
21 that is positioned opposite,
at a predetermined distance (e.g., about 0.5 to 2.0 mm) from the printing medium
8. Electro-thermal converting elements (heat-generating elements)
25,
located along a wall of each of the liquid paths
24 that connect a common
liquid chamber
23 and the discharging orifices
22, generate energy
to be used for ink ejection. In this embodiment, a print head
13 is so configured
that the head cartridge
1 is mounted on the carriage
2, the discharging
orifices
22 are arranged in a direction perpendicular to the scanning direction
of the carriage
2, the corresponding electro-thermal converting elements
(hereinafter also referred to as ejection heaters)
25 are driven (or energized)
based on an image signal or an ejection signal, to cause film boiling of ink in
the liquid paths
24, and the pressure thus generated is used to eject ink
through discharging orifices
22.
FIG. 3 is a schematic block diagram illustrating an example arrangement of a
control circuit for the ink-jet printing apparatus.
In FIG. 3, a controller
100 is a main control unit, and includes a CPU
101, for example, a micro computer, a ROM
103, used to store programs,
required tables and other fixed data, and a RAM
105, which has an area for
developing image data and a work area. A host apparatus
110 is an image
data supplying source (for example, a computer for creating and processing image
data for printing, or an image reader). The image data and other commands and status
signals are exchanged with the controller
100 via an interface (I/F)
112.
A console unit
120 constituted by switches, including a power switch
122
and a recovery switch
126 for instructing the initiation of a suction recovery,
accepts instructions entered by an operator.
Sensors
130 are used to detect the state of the apparatus, and include
the home position sensor
30 described above, a paper end sensor
33
for detecting the presence of a printing medium, and a temperature sensor
134
provided at an appropriate location to detect an environmental temperature.
A head driver
140 drives the ejection heaters
25 of the printing
head
1 in accordance with print data. The head driver
140 includes
a shift register for aligning print data to correspond to the position of the ejection
heaters
25, a latch circuit for latching print data at appropriate timings,
a logical circuit element for driving the ejection heater
25 in synchronization
with a drive timing signal, a timing setting unit for appropriately setting the
drive timing to arrange the dot formation position, and so on.
A sub-heater
142, provided in the printing head
1, adjusts the
temperature
to stabilize the ink discharge characteristic. The sub-heater
142 is formed
on a printing head substrate together with an ejection heater
25, or is
attached to the main body of the printing head
1 or to the head cartridge.
A motor driver
150 drives the main scan motor
4, the sub-scan motor
34 is used to convey (sub-scan) the printing medium
8, and a motor
driver
170 drives the sub-scan motor
34. A feeding motor
35
is used to separately convey the printing medium
8 from the ASF, and a motor
driver
160 drives the feeding motor
35.
The paper feeding processing performed in each state will now be described.
In order to clarify the differences between the present invention and the conventional
art, a conventional fast, consecutive paper feeding method is shown in FIGS. 4A
to 4E.
The paper feeding sequence advances in order from FIGS. 4A to 4E. In FIG. 4A,
a preceding printing medium
8 is sandwiched between the conveyer roller
9 and a pinch roller
50 and conveyed by their conveyance in the sub-scanning
direction. In this state, the output of the paper sensor
33 still indicates
that paper is present. In the conventional art, even if, by reading data in advance,
it is ascertained that data to be printed on a succeeding printing medium
40
is present, the paper feeding should be resumed with the development of the data
in advance, but the paper feeding mechanism cannot be driven for the succeeding
printing medium
40 unless a trailing edge of a preceding printing medium
8 is detected. Therefore, a constant interval is always required before
the preceding printing medium
8 passes through the paper sensor
33.
As a result, in FIG. 4C, the feeding of the succeeding printing medium
40
is initiated and at this time, a distance represented by L appears between the
printing media. Then, in FIG. 4D, the succeeding printing medium
40 passes
through the paper sensor
33, which detects the presence of paper. Based
on this timing the cue position of the succeeding printing medium
40 is
calculated. And in FIG. 4E, the succeeding printing medium
40 reaches the
cue position, the conveyer roller
9 is halted, and the print cartridge
1
is driven in the main scanning direction.
According to the conventional method, the development of data for the succeeding
printing medium
40 is conducted precedingly and parallel processing is executed,
so that overlapping is permitted in the data handling processing and fast consecutive
feeding is enabled accordingly. In addition, since the feeding of the succeeding
printing medium is initiated after an output of the paper sensor
33 is examined,
precise paper feeding can be provided without overlapped paper feeding or the occurrence
of paper jam. However, relative to the feeding time, the distance L is always required.
When the paper sensor
33 is located closer to the feed roller
31,
this distance L is reduced. However, since the feed roller
31 slips on the
surface of a printing medium during the feeding process and an error in conveyed
distance occurs, the error tends to become large when a printing medium must travel
a long distance before it reaches the conveyer roller
9 after passing through
the paper sensor
33.
As an improved conventional method, information concerning the length of a preceding
printing medium
8 is read in advance, and the feeding of a succeeding printing
medium
40 is initiated without considering a trailing edge of the preceding
printing medium
8. According to this method, the succeeding printing medium
40 can be fed at a comparatively short interval L, while the paper sensor
33 is positioned near the conveyer roller
9.
For this method, the information for the length of the preceding printing medium
8 must be obtained in advance. This information can be acquired comparatively
easily if a dedicated paper cassette is employed for each printing medium size,
and it is an effective size detection means. However, with this method, if the
ASF compatible with a universal size printing medium is used instead of a dedicated
paper cassette, the size of a printing medium cannot be determined within a paper
feeding device. In this case, information concerning the size of a printing medium
must be externally provided, by a user's set data on a printer driver in a host
computer. When, for example, a user loads A4 size paper when the setting is for
LETTER size, if the distance between the preceding printing medium
8 and
the succeeding printing medium
40 is too short, these media
8 and
40 will be fed with the trailing edge of the medium
8 and the leading
edge of the medium
40 overlapped, because the A4 size paper is longer. As
a result, the paper sensor
33 cannot detect the trailing edge of the preceding
printing medium
8 or the leading edge of the succeeding printing medium
40, and a printing error will occur.
An embodiment of the present invention is shown in FIGS. 5A to 5E.
In FIGS. 5A to 5E, consecutive paper feeding can be performed with only a minimum
gap defined between a preceding printing medium
8 and a succeeding printing
medium
40. In FIG. 5A, the preceding printing medium
8 has been fed
and is being printed. Then, in FIG. 5B, the accumulated value of the distance by
which the printing medium
8 has been fed after the printing medium
8
passed the paper sensor (edge detection means)
33 is used to calculate the
location of a trailing edge of the preceding printing medium
8 based on
the length of the printing medium
8 obtained in advance. Then, in accordance
with that calculation, it is ascertained that the printing medium
8 and
the printing medium
40 are separated. Then, the paper feeding roller
31
is rotated, and the feeding of the succeeding printing medium
40 from the
ASF is begun. In FIG. 5C, the absence of paper is detected after the preceding
printing medium
8 has passed the paper sensor
33, and the succeeding
printing medium
40 has been fed to a position immediately before the paper
sensor
33. At this time, the location of the leading edge of the succeeding
printing medium
40 already obtained from a value calculated based on the
rotation of the paper feeding roller
31 is used, a check is performed to
determine whether the trailing edge of the preceding medium
8 has passed
the paper sensor
33 and the absence of paper is detected accordingly. In
this state, since the information on the length of the preceding printing medium
is substantially the same as the actual length, the distance L between the preceding
printing medium
8 and the regularly succeeding printing medium
40
is the same as was estimated.
In this state, the succeeding printing medium
40 can be successively fed
to the conveyor roller
9, without the stoppage of the paper feeding. As
a result, the printing media, separated with a minimum paper feeding interval,
can be consecutively fed at high speed without paper overlapping occurring, while
at the same time, precise control of the cue position of the succeeding printing
medium
40 is ensured. Subsequently, in FIG. 5D, the preceding printing medium
8, which is not shown, has been discharged, and the succeeding printing
medium
40 has been delivered to and positioned at the conveyor roller
9.
In FIG. 5E, the paper feeding process has been completed and the printing is being performed.
FIGS. 6A to 6E depict the processings in the above-mentioned embodiment, which
is performed when the actual length of a preceding printing medium
8 differs
from the length obtained in advance. In this embodiment, the actual length of the
preceding printing medium
8 is longer than the length obtained in advance.
In FIG. 6A, the preceding printing medium
8 has been fed and is being printed.
Then, in FIG. 6B, the accumulated value of the distance by which the printing medium
8 has been fed after the printing medium
8 passed the paper sensor
(edge detection means)
33 is used to calculate the location of a trailing
edge of the preceding printing medium
8 based on the length of the printing
medium
8 obtained in advance. Then, in accordance with that calculation,
it is ascertained that the printing medium
8 and the printing medium
40
are separated. Then, the paper feeding roller
31 is rotated, and the feeding
of the succeeding printing medium
40 from the ASF is begun. However, since
the actual length of the preceding printing medium
8 is longer than the
length obtained in advance, the preceding printing medium
8 and the succeeding
printing medium
40 are fed in an overlapped state. In FIG. 6C, it is calculated
by the rotation of the paper feeding roller
31 that the succeeding printing
medium
40 has been fed to a location immediately preceding the paper sensor
33, and at that time, a check is performed to determine whether the absence
of paper is presently detected by detecting whether the preceding printing medium
8 has passed the paper sensor
33. In this case, since the actual
length of the preceding printing medium
8 is longer than the length obtained
in advance in the printing apparatus, the rotation of the paper feeding roller
31 is halted, or the rotation speed is reduced, so that the succeeding printing
medium
40 does not arrive at the paper sensor
33. In FIG. 6D, the
preceding printing medium
8 has passed the paper sensor
33 and then
the absence of paper is presently detected. At this time, the rotation of the paper
feeding roller
31 is resumed at such timing that the interval between the
preceding and succeeding printing media
8 and
40 may be equal to
the distance L. And finally, in FIG. 6E, the paper feeding process has been completed
and the printing of the succeeding printing medium is performed.
As described above, according to the present invention, even if the actual length
of a printing medium
8 differs from the length set in advance, the paper
feeding process is performed correctly, and the cue position of the succeeding
printing medium
40 may be controlled precisely. Further, the minimum interval
L, as required, can be maintained.
The above processing performed by the CPU
101 will now be described referring
to the flowchart shown in FIG. 7. At Step
10, upon the receipt of a paper
feeding instruction, a paper feeding mode is initiated. At Step
20, information
concerning the length of a printing medium to be supplied is obtained. In this
embodiment, the information is obtained from page length (information concerning
the length of printing medium) in the settings on a printing medium of the print
information received from a printer driver at a host computer end. The above information
may be obtained from other information used to specify the length, such as information
concerning the size, shape or type of a paper cassette and the width of a printing
medium. A flow thereafter advances to Step
30. At Step
30, a check
is performed to determine whether a preceding printing medium
8 is currently
being printed. If the preceding printing medium
8 is not currently being
printed, at Step
40 the paper sensor is employed to determine whether the
preceding printing medium
8 is still present in the printing area. If the
preceding printing medium
8 is still present in that area, at Step
50,
the LF mode is activated to execute a paper discharge process, and the preceding
printing medium
8 is discharged. However, when the discharge process has
been completed, at Step
60 an initial paper feeding routine is begun. The
initial paper feeding routine is for feeding a first sheet, and when the paper
feeding routine has been completed, the flow advances to Step
100, whereat
the paper feeding mode is terminated and the actual printing is begun.
However, if at Step
30 the preceding printing medium
8 is
currently being printed, the flow shifts to Step
70, and a position of a
trailing edge of the preceding printing medium
8 is calculated. Then at
Step
80, according to where the position of the trailing edge of the preceding
printing medium
8 is, it is determined whether a succeeding printing medium
40 can be separated and fed from the ASF
32. If the preceding printing
medium
8 has reached a location where the paper feeding process can be initiated,
at Step
90 a consecutive paper feeding routine is activated. Then, when
the paper feeding process has been completed, the flow advances to Step
100
and the paper feeding mode is terminated.
The initial paper feeding routine will be now described. This routine is initiated
at Step
210 in FIG. 8. At Step
220, the calculation of the cue position
of a printing medium to be fed is performed, and at Step
230 the rotation
of the paper feeding roller
31 at the ASF
32 is begun. Generally,
for a serial printer, after printing has begun, printing media are intermittently
delivered in the sub-scanning direction. In order to prevent the precision of the
delivery from being deteriorated due to the application of pressure to the fed
printing media by the paper feeding roller, a semi-circular roller is frequently
employed. Therefore, the paper feeding roller
31 is rotated once to complete
the paper feeding process, and is then halted. At Step
230, an instruction
is issued to start the rotation of the paper feeding roller
3, and at Step
240, a check is performed to determine whether the paper feeding roller
3 has been rotated once. Since at the time the paper feeding process is
initiated, the paper feeding roller
31 is not, of course, being rotated,
the flow advances to Step
260, whereat the preceding printing medium
8
arrives at the paper sensor
33. If the paper feeding roller
31 has
completed the rotation before the preceding printing medium
8 has reached
the paper sensor
33, it is determined that a paper feeding failure has occurred
because of slippage at the printing medium, or that no printing medium is loaded
in the ASF
32. The flow then shifts to Step
250, whereat the occurrence
of an error is indicated. At Step
260, at the time when the preceding printing
medium
8 has reached the paper sensor
33, the rotation of the ASF
32 is continued until one full revolution has been completed. The flow then
advances to Step
270, whereat the rotation of the conveyor roller
9
is performed to complete the feeding of the paper. At this time, the feeding distance
of the printing medium
8 is calculated when the paper sensor
33 detects
the presence of paper, then the rotation of the conveyor roller
9 is driven
to feed the preceding printing medium
8 to the cue position. And the initial
paper feeding routine is terminated.
The consecutive paper feeding routine will now be explained referring to FIG.
9. At Step
300, the consecutive paper feeding routine is initiated, and
at Step
310, the calculation of the cue position of the succeeding printing
medium
40 is begun. Then, at Step
320 the position of the trailing
edge of the preceding printing medium
8 is calculated using information
concerning the length of the printing medium obtained in advance. The positional
information on the trailing edge of the preceding printing medium
8 is subtracted
from the leading edge of the succeeding printing medium
40 to obtain positional
difference information. At Step
330, the positional difference information
is employed to determine whether the rotation of the paper feeding roller
31
of the ASF
32 should be begun to separate and feed a succeeding printing
medium
40. This positional difference information may be either positive
or negative, and in this embodiment, positive information is defined as representing
a state wherein there is no overlap of paper, while the negative information is
defined as representing there is such overlap. In short, as a condition it is only
necessary that the preceding printing medium
8 has already passed the paper
feeding roller
31 and thus the succeeding printing medium
40 can
be separated and fed. In this embodiment, the positional difference information
is used to control the rotation of the paper feeding roller
31. However,
information on the distance from the paper feeding roller
31 may be employed
regarding the start of the rotation of the paper feeding roller
31. At Step
340, the rotation of the paper feeding roller
31 of the ASF
32
is begun. And at Step
342, the position of the leading edge of the succeeding
printing medium
40 is calculated, and at Step
344, it is determined
whether the printing medium
8 has reached a location immediately preceding
the paper sensor
33. This determination process is repeated until the leading
edge of the succeeding printing medium
40 is positioned immediately before
the paper sensor
33. When it is determined that the leading edge of the
succeeding printing medium
40 has reached the location preceding the paper
sensor
33, at Step
350 a check is performed to determine whether
the paper sensor
33 indicates the absence of paper based on a detection
result of the trailing edge of the preceding printing medium
8. If the absence
of paper is not detected, the feeding of the succeeding printing medium
40
is stopped at Step
360. In this embodiment, instead of the slippage of the
feeding, the reduction of the feeding speed may be done. In this state, the preceding
and succeeding printing media
8 and
40 are fed while overlapping
each other, or while there is almost no interval between them. While the paper
feeding is halted, the preceding printing medium
8 is independently transported
by the conveyor roller
9, which is a sub-scanning mechanism. Therefore,
at a certain time the paper sensor
33 detects the presence of paper. At
this time, the minimum required interval between the preceding and the succeeding
printing media
8 and
40 is kept, and thereafter, at Step
370
the rotation of the paper feeding roller
31 and the paper feeding are resumed.
Subsequently, at Step
380 the conveyor roller
9 is rotated at the
same speed as the paper feeding speed, and at Step
390 the preceding printing
medium
8 is conveyed in the sub-scanning direction until it reaches the
cue position. Then, when the cue position is OK, at Step
400 the consecutive
paper feeding routine is terminated.
In the above embodiment, paper feeding control is exercised by using the information
concerning the length of the printing medium obtained from the host computer. However,
identification information for a paper cassette, key entry performed at the printing
apparatus, or information from any sensor to obtain the length of a printing medium
in the printing apparatus may be employed for the control.
As another example, the length information of the printing medium may be a fixed
value. In this case, the fast feeding effects obtained by employing consecutive
paper feeding vary depending on the length of a printing medium; however, the fixed
value information is an effective means to use when the length of a printing medium
that is normally used is comparatively fixed. A specific explanation will now be
given for a case wherein LETTER size is used as
