U.S. patent application number 11/751867 was filed with the patent office on 2007-10-25 for methods for moving a media sheet within an image forming device.
Invention is credited to Larry Steven Foster, Darin M. Gettelfinger, Paul Douglas Horrall, Franklin Joseph Palumbo, John Spicer, Kenji Totsuka, Christopher Kent Washing.
Application Number | 20070246880 11/751867 |
Document ID | / |
Family ID | 46327935 |
Filed Date | 2007-10-25 |
United States Patent
Application |
20070246880 |
Kind Code |
A1 |
Totsuka; Kenji ; et
al. |
October 25, 2007 |
Methods For Moving A Media Sheet Within An Image Forming Device
Abstract
The present application is directed to methods and devices for
determining a media level in an input area within an image forming
device. In one embodiment, a support section configured to hold a
stack of media sheets is positioned in the image forming device. A
pick mechanism is positioned to contact a top-most media sheet of
the stack of media sheets in the support section. The pick
mechanism may include a pick motor and a pick roller. A sensor
roller may be positioned separate from the pick roller and in
contact with the top-most media sheet. A controller may determine
the media level based on a movement of the sensor roller after the
top-most media sheet has moved to a predetermined location.
Inventors: |
Totsuka; Kenji; (Lexington,
KY) ; Spicer; John; (Lexington, KY) ; Palumbo;
Franklin Joseph; (Nicholasville, KY) ; Gettelfinger;
Darin M.; (Lexington, KY) ; Horrall; Paul
Douglas; (Lexington, KY) ; Washing; Christopher
Kent; (Lexington, KY) ; Foster; Larry Steven;
(Lexington, KY) |
Correspondence
Address: |
John J. McArdle, Jr.;Lexmark International, Inc.
Intellectual Property Department, 740 West New Circle Road
Lexington
KY
40550
US
|
Family ID: |
46327935 |
Appl. No.: |
11/751867 |
Filed: |
May 22, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11406579 |
Apr 19, 2006 |
|
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|
11751867 |
|
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Current U.S.
Class: |
271/109 |
Current CPC
Class: |
B65H 2553/51 20130101;
B65H 2511/152 20130101; B65H 2511/514 20130101; B65H 2220/01
20130101; B65H 2513/511 20130101; B65H 2220/01 20130101; B65H
2220/01 20130101; B65H 2220/03 20130101; B65H 3/0684 20130101; B65H
2701/1311 20130101; B65H 2701/1313 20130101; B65H 2551/20 20130101;
B65H 2220/01 20130101; B65H 2220/02 20130101; B65H 2511/514
20130101; B65H 2513/511 20130101; B65H 2701/1313 20130101; B65H
2301/423245 20130101; B65H 2701/1311 20130101; B65H 7/02 20130101;
B65H 2511/152 20130101 |
Class at
Publication: |
271/109 |
International
Class: |
B65H 3/06 20060101
B65H003/06 |
Claims
1. A device to determine a media level within an image forming
devices the device comprising: a pick mechanism to feed media
sheets from a stack of media sheets; a sensor roller to contact a
top-most media sheet of the media stack, the sensor roller rotates
when the top-most media sheet is being fed by the pick mechanism; a
media position sensor located downstream from the sensor roller;
and a controller configured to determine the media level based on
movement of the sensor roller and a time for the top-most media
sheet to move from the media stack to the media position
sensor.
2. The device of claim 1, wherein the controller is configured to
determine the media level based on a difference between when the
top-most media sheet is picked by the pick roller and when the
top-most media sheet is sensed by the media position sensor.
3. The device of claim 1, wherein the controller is configured to
determine the media level based on a time from when a pick
mechanism begins to move the top-most media sheet from the media
stack until the top-most media sheet is sensed by the media
position sensor.
4. The device of claim 1, wherein the pick mechanism is configured
to move the top-most media sheet from the media stack to the media
position sensor.
5. The device of claim 1, wherein the pick mechanism further
comprises a pick roller positioned to contact the top-most media
sheet of the media stack, wherein the pick roller and sensor roller
are spaced apart and simultaneously contact the top-most media
sheet while the media sheet is being fed.
6. The device of claim 5, wherein the pick roller and the sensor
roller are each positioned at an input tray.
7. The device of claim 5, wherein the pick roller is mounted on a
first arm and the sensor roller is mounted on a second arm.
8. A device to determine a media level within an image forming
device, the device comprising: a sensor roller positioned to
contact a top-most media sheet of a stack of media sheets, the
sensor roller being rotated when the top-most media sheet moves
from the media stack; a media position sensor located downstream
from the sensor roller; and a controller configured to determine
the media level based on movement of the sensor roller and a time
for the top-most media sheet to move from the media stack to the
media position sensor.
9. The device of claim 8, further comprising a pick mechanism to
contact and drive the top-most media sheet from the media
stack.
10. The device of claim 8, wherein the sensor roller further
includes a plurality of indicators that are sensed by a sensor
during rotation of the sensor roller.
11. The device of claim 8, further comprising a sensor wheel
positioned adjacent to the sensor roller, the sensor wheel
including a plurality of indicators that are sensed by a sensor
during rotation of the sensor roller.
12. The device of claim 9, wherein the pick mechanism is mounted on
a first arm and the sensor roller is mounted on a second arm.
13. The device of claim 9, wherein the pick mechanism and the
sensor roller simultaneously contact the top-most media sheet while
the media sheet is being fed.
14. A method of determining a media level within an image forming
device, the method comprising the steps of: sending a signal to
begin rotating a pick roller that is in contact with a top-most
media sheet in a stack of media sheets; receiving feedback from a
sensor roller also in contact with the top-most media sheet
indicating movement of the top-most media sheet; receiving a signal
from a media position sensor that the top-most media sheet is at a
predetermined position downstream from the media stack; and
determining the media level based on movement of the sensor roller
and receiving the signal from the media position sensor.
15. The method of claim 14, wherein the step of receiving a
feedback from the sensor roller in contact with the top-most media
sheet further comprises sensing indicators on the sensor roller
that move past a sensor during rotation of the sensor roller.
16. The method of claim 14, wherein the step of receiving a
feedback from a sensor roller in contact with the topmost media
sheet further comprises sensing indicators on a sensor wheel
positioned adjacent to the sensor roller, the indicators moving
past a sensor during rotation of the sensor roller.
17. The method of claim 14, wherein the step of determining the
media level based on movement of the sensor roller comprises
determining the number of rotations of the sensor roller between
sending the signal to the pick roller to begin rotating and
receiving the signal from the media position sensor.
18. The method of claim 14, wherein the step of determining the
media level based on movement of the sensor roller comprises
determining the time of rotation of the sensor roller between
sending the signal to the pick roller to begin rotating and
receiving the signal from the media position sensor.
19. The method of claim 14, wherein the step of receiving a
feedback from a sensor roller in contact with the top-most media
sheet further comprises driving the sensor roller to rotate by
moving the top-most media sheet from the media stack.
20. The method of claim 14, wherein the step of determining the
media level further comprises displaying the media level on a
control panel of the image forming device.
Description
RELATED APPLICATIONS
[0001] The present application is a continuation-in-part of
previously filed U.S. patent application Ser. No. 11/406,579 filed
on Apr. 19, 2006 and entitled "Methods for Moving a Media Sheet
within an Image Forming Device" which is herein incorporated by
reference in its entirety.
BACKGROUND
[0002] The present application is directed to methods and devices
for controlling operation of an image forming device and, more
specifically, to methods and devices for determining a media level
in arm input area.
[0003] Image forming devices, such as a color laser printer
facsimile machine, copier, all-in-one device, etc, may include a
double transfer system for producing images. Toner is initially
transferred from a photoconductive member to an intermediate member
at a first transfer location, and then from the intermediate member
to the media sheet at a second transfer location. As the toner is
being moved towards the second transfer location, a media sheet is
moved along a media path to receive the toner image.
[0004] The media sheet and toner image should reach the second
transfer location at about the same time. If the media sheet
arrives before the toner image, the toner image may be transferred
to the media sheet at a position that is too low or partially off
the bottom of the sheet. Conversely, if the media sheet arrives
after the toner image, the toner image may be transferred at a
position that is too high or partially off the top of the
sheet.
[0005] The media path may be configured to allow for increasing and
decreasing the speed of the media sheet and thus affect the timing
that the media sheet reaches the second transfer location. However,
the amount of correction may be limited and large corrections
cannot be made. Inherent with this concept is that a shorter media
path offers less opportunity for correction. Many image forming
devices include short media paths in an effort to reduce the
overall size of the device. Therefore, proper timing and media
sheet movement is important for these devices as there is limited
room for corrections.
SUMMARY
[0006] The present application is directed to methods and devices
for determining a media level in an input area within an image
forming device. In one embodiment, a support section configured to
hold a stack of media sheets is positioned in the input area of the
image forming device. A pick mechanism is positioned to contact a
top-most media sheet of the stack of media sheets in the support
section. The pick mechanism may include a pick motor and a pick
roller. A sensor roller may be positioned separate from the pick
roller and in contact with the top-most media sheet. A controller
may determine the media level based on a movement of the sensor
roller after the top-most media sheet has moved to a predetermined
location.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a schematic view illustrating an image forming
device according to one embodiment.
[0008] FIG. 2 is a perspective view illustrating a sensor according
to one embodiment.
[0009] FIG. 3 is a schematic view illustrating a pick mechanism,
sensor, and a controller according to one embodiment.
[0010] FIG. 4 is a perspective view illustrating a sensor according
to one embodiment.
[0011] FIG. 5 is a schematic view illustrating an image forming
device according to one embodiment.
[0012] FIG. 6 is a schematic view illustrating a media sheet path
according to one embodiment.
[0013] FIG. 7 is a process diagram for a control process according
to one embodiment.
[0014] FIG. 8 is a schematic view of a pick mechanism and a sensor
according to one embodiment.
DETAILED DESCRIPTION
[0015] The present application is directed to methods and devices
for detecting a media level in an input area of an image forming
device. The input area may include a support section to contain a
stack of media sheets. A pick mechanism may also be located in the
input area. The pick mechanism may initiate movement of a top-most
media sheet of the media stack. The input area may also include a
sensor that may be positioned to also contact the top-most media
sheet. The media sheet sensor senses movement of the top-most media
sheet as the sheet is moved in response to the pick mechanism. A
controller may oversee the operation of the input area. The
controller may be configured to determine the media level in the
input area by obtaining a feedback from the sensor.
[0016] One embodiment of an image forming apparatus is illustrated
in FIG. 1. The device 10 includes a support section 11 including a
ramp 12 and being sized to contain a stack of media sheets 13. A
pick mechanism 20 is positioned at the support section 11 for
moving a top-most sheet from the stack 13 along the ramp 12 and
into a media path 15. Pick mechanism 20 includes an arm 22 and a
roller 21. Arm 22 is pivotally mounted to maintain the roller 21 in
contact with the top-most sheet of the stack 13. Pick mechanism 20
may include a clutch 29 that affects the movement of the roller 21.
In one specific embodiment, clutch 29 is a ball clutch as disclosed
in U.S. patent application Ser. No. 10/436,406 entitled "Pick
Mechanism and Algorithm for an Image Forming Apparatus" filed on
May 12, 2003, and herein incorporated by reference. A sensor 30 is
positioned at the support section 11 to track the movement of the
media sheet as will be explained in detail below. The media sheets
from the support section 11 are moved along the media path 15 to a
second transfer area 40 where they receive a toner image from an
image formation area 50.
[0017] The image formation area 50 includes a laser printhead 51,
one or more image forming units 52, and a transfer member 53. Laser
printhead 51 includes a laser that discharges a surface of
photoconductive members 54 within each of the image forming units
52. Toner from a toner reservoir is attracted to the surface area
affected by the laser printhead 51. In one embodiment, the toner
reservoirs (not illustrated) are independent of the image forming
units and can be removed and replaced from the device 10 as
necessary. In another embodiment, the toner reservoirs are integral
with the image forming units 52. In one embodiment, the device 10
includes four separate image forming units 52 each being
substantially the same except for the color of the toner. In one
embodiment, the device 10 includes image forming units 52 for use
with black, magenta, cyan, and yellow toner.
[0018] The transfer member 53 extends continuously around a series
of rollers 55. The member 53 receives the toner images from each of
the photoconductive members 54 and moves the images to the second
transfer area 40 where the toner images are transferred to the
media sheet. If one embodiment, the toner images from each of the
photoconductive members 54 are placed onto the member 53 in an
overlapping arrangement. In one embodiment, a multi-color toner
image is formed during a single pass of the transfer member 53. By
way of example as viewed in FIG. 1, the yellow toner is placed
first on the transfer member 53, followed by cyan, magenta, and
black.
[0019] The second transfer area 40 includes a nip formed by a
second transfer roller 41. A media sheet is moved along the media
path 15 through the nip and receives the toner images from the
transfer member 53. The media sheet with the toner images next
moves through a fuser 42 to adhere the toner images to the media
sheet. The media sheet is then either discharged into an output
tray 43 or moved into a duplex path 45 for forming a toner image on
a second side of the media sheet. Examples of the device 10 include
Model Nos. C750 and C752, each available from Lexmark
International, Inc. of Lexington, Ky., USA. In another embodiment,
the device is a mono printer comprising a single image forming unit
42 for forming toner images in a single color. A control panel 44
may be positioned on an exterior surface of an image forming device
10. Commands may be entered through the control panel 44 to control
the operation of the image forming device 10. For example, commands
to switch modes (e.g., color mode, monochrome mode), view the
number of imagers printed, take the device 10 on/off line to
perform periodic maintenance, and the like may be entered. The
control panel 44 may also include a display panel.
[0020] In some embodiments as illustrated in FIG. 1, the time
necessary to move a media sheet from the support section 11 to the
second transfer area 40 is less than the time to form a toner image
on the transfer member 53 and move the toner image to the second
transfer area 40. This results in the placement of the toner images
on the member 53 before the media sheet is picked from the support
section 11. Further, this small distance from the support section
11 to the second transfer area 40 provides little room to correct
problems with the timing of the media sheets. Therefore, the media
sheets should be picked from the support section 11 in a timely
manner and accurately moved along the media path 15.
[0021] As illustrated in FIGS. 1 and 2, a sensor 30 is positioned
at the support section 11 to determine the position of the media
sheet. As best, illustrated in FIG. 2, sensor 30 includes an arm 31
that is pivotally attached to a body of the apparatus 10. A roller
32 is positioned towards an end of the arm 31 and remains in
contact with a top-most sheet within the stack 13. A sensor wheel
33 is operatively connected to rotate with the roller 32. The
sensor wheel 33 includes a plurality of indicators 34, such as
apertures or printed lines, spaced along the circumference of the
wheel. In one embodiment, each indicator 34 has a substantially
rectangular shape and is positioned around a center of the wheel
similar to spokes of a wheel. In one embodiment, each indicator 34
is substantially the same size and evenly spaced from the other
indicators 34. In another embodiment, indicators 34 have a
plurality of different shapes and sizes, and may be located at
different positions along the wheel 33.
[0022] A sensor 35 detects rotational movement of the wheel 33. In
one embodiment, sensor 35 includes an emitter 36 and a receiver 37.
In one embodiment, emitter 36 emits an optical signal that is
detected by the receiver 37. As the wheel 33 rotates, the
indicators 34 move past the emitter 36 that cause the signal to
pass to the receiver 37. Likewise, the other sections of the wheel
33 move past the emitter 36 and prevent the signal from passing to
the receiver 37. A controller 100 (FIG. 3) counts the number of
pulses and the frequently of the pulses to determine the speed and
location of the media sheet.
[0023] The emitter 36 may generate any color or intensity of light.
The emitter 36 may generate monochromatic and/or coherent light,
such as for example, a gas or solid-state laser. Alternatively, the
emitter 36 may emit non-coherent light of any color or mix of
colors, such as any of a wide variety of visible-fight, infrared or
ultraviolet light emitting diodes (LEDs) or incandescent bulbs. In
one embodiment, the emitter 36 generates optical energy in the
infrared range, and may include an infrared LED. The receiver 37
may comprise any sensor or device operative to detect optical
energy emitted by the emitter 36. In one specific embodiment, the
emitter 36 is an infrared LED optical emitter and the receiver 37
is a silicon phototransistor optical detector.
[0024] FIG. 3 illustrates one embodiment of the input area and
media path 15 that leads to the second transfer area 40. The sensor
30 is positioned within the input area to determine the movement of
the media sheets from the media stack 13. A second sensor 39 is
positioned along the media path 15 between the support section 11
and the second transfer area 40. The second sensor 39 determines
the exact position of the media sheet as it moves towards the
second transfer area 40. A wide variety of media sensors are, known
in the art. In general, the sensor 39 may comprise an
electromechanical contact that is made or broken when a media sheet
trips a mechanical lever disposed in the media sheet path; an
optical sensor whereby a media sheet blocks, attenuates, or
reflects optical energy from an optical source, to an optical
detector; an opto-mechanical sensor, or other sensor technology, as
well known in the art. In one embodiment, the second sensor 39 is
positioned about 30 mm upstream from the second transfer area
40.
[0025] Controller 100 oversees the timing of the toner images and
the media sheets to ensure the two substantially coincide at the
second transfer area 40. In one embodiment, controller 100 operates
such that the two coincide within +/-0.5 mm. In one embodiment as
illustrated in FIG. 3, controller 100 includes a microcontroller
with associated memory 101. In one embodiment, controller 100
includes a microprocessor, random access memory, read only memory,
and in input/output interface. Controller 100 monitors when the
laser printhead 51 begins to place the latent image on the
photoconductive members 54, and at what point in time, the first
line of the toner image is placed onto the transfer member 53. In
one embodiment, controller 100 monitor scan data from the laser
printhead 51 and the number of revolutions and rotational position
of motor 82 that drive the photoconductive members 54. In one
embodiment, a single motor 82 drives each of the photoconductive
members 54. In one embodiment, two or more motors 82 drive the
plurality of photoconductive members 54. In one embodiment, the
number of revolutions and rotational position of motor 82 is
ascertained by a sensor 83.
[0026] In one embodiment, the controller 100 interfaces with the
control panel 44. The control panel 44 may be located on an outer
surface of the device 10 to facilitate input of commands to control
operation of the device 10. The control panel 44 may also
facilitate the input of data stored in memory 101 and further
utilized by the controller 100. In one embodiment, the controller
100 uses data stored in memory 101 to determine whether media is
present in the support section 11.
[0027] In one embodiment, as the first writing line of the toner
image is transferred onto the member 53 controller 100 begins to
track incrementally the position of the image on member 53 by
monitoring the number of revolutions and rotational position of a
motor 80 that rotates the member 53. In one embodiment, a sensor 84
ascertains the number of revolutions and rotational position of the
motor 80. From the number of rotations and rotational position of
the motor 80, the linear movement of member 53 and the image
carried thereby can be directly calculated. Since both the location
of the toner image on member 53 and the length of member between
the transfer nips 59a, 59b, 59c, 59d and second transfer area 40 is
known, the distance remaining for the toner images to travel before
reaching the second transfer area 40 can also be calculated.
[0028] In one embodiment, the position of the image on the member
53 is determined by HSYNCs that occur when the laser printhead 51
makes a complete scan over one of the photoconductive members 54.
Controller 100 monitors the number of HSYNCs and can calculate the
position of the image. In one embodiment, one of the colors, such
as black, is used as the HSYNC reference for determining timing
aspects of image movement. The HSYNCs occur at a known periodic
rate and the intermediate member surface speed is assumed to be
constant.
[0029] At some designated time, pick mechanism 20 receives a
command from the controller 100 to pick a media sheet, Motor 81
that drives the pick mechanism 20 is activated and the pick roller
21 begins to rotate and move the media sheet from the stack 13 in
the support section 11 into the media path 15. As the media sheet
begins to move, the sensor roller 32 and wheel 33 rotate and are
detected by the sensor 35. The pick roller 21 continues to rotate
and the media sheet moves along the media path 15.
[0030] The media sheet moves through the beginning of the media
path 15 and eventually trips the media sensor 39. At this point,
the controller 100 ascertains the exact location of the leading
edge of the media sheet and can incrementally track the continuing
position by monitoring the feedback of a sensor 85 associated with
pick mechanism motor 81. In one embodiment, because of the short
length of the media path 15, pick mechanism 20 moves the media
sheet from the support section 11 and into the second transfer area
40. Therefore, the remaining distance from the media sheet to the
second transfer area 40 can be calculated from the known distance
between the sensor 39 and second transfer area 40 and feedback from
the sensor 85. One embodiment of a feedback system is disclosed in
U.S. Pat. No. 6,330,424, assigned to Lexmark International, Inc.,
and herein incorporated by reference.
[0031] The media path 15 can be divided into two separate sections:
a first section that extends between the support section 11 to a
point immediately upstream from the sensor 39; and a second section
that extends from the sensor 39 to the second transfer area 40.
Sensor 30 provides information to the controller 100 when the media
sheet is moving through the first section. Information relating to
the second section may be obtained from one or more of the sensor
39, motor 81 and sensor 85.
[0032] Controller 100 may use feedback from the sensor 85 to
correct variations in the media movement through the first section,
Controller 100 may be programmed to assume that activation of the
motor 81 results in the media sheet being moved a predetermined
amount. However, various factors may result in the media sheet
advancing through the first section faster or slower than expected.
Some variations are corrected during the first section, and other
variations are corrected during the second section. In both
corrections, pick mechanism 20 is accelerated or decelerated as
necessary.
[0033] In some embodiments, the media sheet is not moved as fast as
expected causing the media sheet to lag behind the expected
location. Causes of a lagging media sheet may include the clutch 29
on the pick roller 21 not engaging, slippage between the pick
roller 21 and the media sheet, and wear of the pick roller 21. In
each instance, the media sheet is behind the expected location. The
amount of lag may be detected based on feed back from the sensor
sensor 35. Sensor 35 detects the amount of movement of the media,
sheet that is compared by the controller 100 with the expected
amount of movement. Any discrepancy, can then be corrected by
accelerating the pick mechanism 20 accordingly.
[0034] Some variations from the expected position may be corrected
in the second section. Examples of these include media stack height
uncertainty, and poorly loaded media sheets that are pre-fed up the
ramp 12. Because these errors are not caused by the pick mechanism
20, the amount of error is unknown until the leading edge is
detected at sensor 39. Once the leading edge is detected, the
amount of deviation is determined and the pick mechanism 20 can be
accelerated or decelerated as necessary to deliver the media sheet
to the second transfer area 40 at the proper time.
[0035] Further, feedback from the sensor 39 can be used in
combination with the sensor 35 for feeding future media sheets. By
way of example, the height of the media stack 13 is unknown when
feeding a first sheet. The controller 100 may estimate an expected
travel time and activate the pick mechanism 20 at a corresponding
time. Once the leading edge reaches the sensor 39, the feedback
from the sensor 35 can be used to determine the distance the sheet
traveled from the stack 13 to the sensor 39 to determine the height
of the media stack 13. With this information, controller 100 is
able to more accurately predict future pick timings. More specific
embodiments for determining the media level within the support
section 11 are described below.
[0036] FIG. 4 illustrates another embodiment of the sensor 30.
Roller 32 is rotatably mounted on an arm 31. The roller 32 includes
a plurality of indicators 34 that move past a sensor 35. The sensor
35 includes an emitter (not illustrated) and a receiver 37. The
roller 32 is maintained in contact with the top-most sheet of the
media stack 13 as the arm 31 pivots about a point 89. Movement of
the top-most media sheet causes the roller 32 to rotate which is
detected by the sensor 35.
[0037] It should be noted that the image-forming device 10
illustrated in the previous embodiments is a two-stage
image-forming apparatus. In two-stage transfer apparatus, the toner
image is first transferred to a moving transport member 53, such as
an endless belt, and then to a print media at the second transfer
area 40. However, the present devices and methods are not so
limited, and may be employed in single-stage or direct transfer
image-forming device 80, such as the image-forming device, shown in
FIG. 5.
[0038] In such a device 80, the pick mechanism 20 picks an upper
most print media from the media stack 13, and feeds it into the
primary paper path 15. Sensor 30 is positioned at the input area
and includes an arm 31 including a roller 32 and sensor wheel 33.
The roller 32 is positioned on the topmost sheet and movement of
the sheet causes the sensor wheel 33 to rotate which is then
detected by sensor 35. In one embodiment, media rollers 16 are
positioned between the pick mechanism 20 and the first image
forming station 52. The media rollers 16 move the media sheet
further along the media path 15 towards the image forming stations
52, and may further align the sheet and more accurately control the
movement. It one embodiment, the rollers 16 are positioned in
proximity to the input area such that the media sheet remains in
contact with the sensor 30 as the leading edge moves through the
rollers 16. In this embodiment, sensor 30 may monitor the location
and movement of the media sheet which can then be used by the
controller 100. In another embodiment, the media sheet has moved
beyond the sensor 30 prior to the leading edge reaching the rollers
16.
[0039] The image forming device 80 may also include a multipurpose
feeder 60 that may be configured to allow feeding of media such as
envelopes, post cards, transparencies, or card stock, as well as
media that may be too large to fit in the support section 11. The
multipurpose feeder 60 may also be used to manually feed media. A
pick mechanism 61 picks a top-most media sheet from a media stack
70 in a support section 68 and feeds it into the media path 15. A
media sheet sensor 63 is positioned in the input area and includes
an arm 64 including a sensor roller 65 and a sensor wheel 66. The
sensor roller 65 is positioned to contact the top-most media sheet
of the media stack 70. Movement of the media sheet causes the
sensor roller 65 to rotate which is then detected by a sensor 67.
In one embodiment, media rollers 16 are positioned between the pick
mechanism 61 and a first image forming station 52. The media
rollers 16 move the media sheet further along the media path 15
towards the image forming stations 52, and may further align the
sheet and more accurately control the movement. In one embodiment,
the rollers 16 are positioned in proximity to the input area such
that the media sheet remains in contact. With the media sheet
sensor 63 as the leading edge moves through the rollers 16. In this
embodiment, media sheet sensor 63 monitors the location and
movement of the media sheet which can then be used by the
controller 100. In another embodiment, the media sheet has moved
beyond the media sheet sensor 63 prior to the leading edge reaching
the rollers 16.
[0040] The transport member 53 conveys the media sheet past each
image-forming station 52. Toner images from the image forming
stations 20 are directly transferred to the media sheet. The
transport member 53 continues to convey the print media with toner
images thereon to the fuser 42. The media sheet is then either
discharged into the output tray 43, or moved into the duplex path
45 for forming a toner image on a second side of the print
media.
[0041] In one embodiment, the roller 21 of the pick mechanism 20 is
mounted on a first, arm 22, and the sensor roller 32 is mounted on
a second arm 31. In one embodiment, the pick roller 21 is
positioned downstream of the sensor roller 32.
[0042] The sensor 30 may further be able to detect the trailing
edge of the media sheet as it leaves the media stack 13. As the
media sheet is moved from the stack 135 the sensor 30 senses the
sheet until the trailing edge moves beyond the roller 32. At this
point, the roller 32 stops rotating and a signal may be sent to the
controller 100 indicating that the location of the trailing edge.
The controller 100 may then begin picking the next media sheet
based on the known location of the trailing edge. By knowing this
location, the controller 100 does not need to wait for a minimum
gap to be formed between the trailing edge and the next sheet. The
next sheet may then be picked once the trailing edge is clear and
the pick mechanism 20 is ready to pick the next media sheet from
the stack 13.
[0043] Early picking of a media sheet may have several advantages.
First, picking the next media sheet early allows the pick mechanism
20 to tolerate slippage between the pick roller 21 and media sheet,
and clutch errors. Second, the staging system may be, able to
tolerate more error when the media sheet is early because it can
eliminate more error by decelerating than by accelerating. Third,
if no media sheet movement is detected by the sensor 35, the
controller 100 can stop the pick mechanism 20 and reinitiate the
pick. Reinitiating may occur prior to the error becoming so large
that the staging zones could not remove the error.
[0044] In one embodiment, pick mechanism 20 moves the media sheet
from the support section 11 (e.g., an input tray) and into the
second transfer area 40. As the media level in the support section
11 changes, the length of the path from a leading edge of the
top-most media sheet at the ramp 12 to the media position sensor 39
also changes. This is illustrated in FIG. 6 where D is the distance
from the leading edge of the top-most media sheet (Point B) to the
media position sensor 39 when the support section 11 is full, and
D.sub.2, is the distance from the leading edge of the top-most
media sheet to the media position sensor 39 when the support
section 11 is nearly empty. When the pick roller 21 moves the
top-most media sheet, the sheet may follow a path approximated by
A-B'-C. The length of this path may continually increase as the
media level decreases and each successive sheet that is fed from
the support section 11 may have a longer distance to travel before
encountering the media position sensor 39. Therefore, the amount of
movement of the sensor roller 32 increases as the media level in
the support section 1 decreases. Experimentation has shown that the
media level can be estimated through an empirical relationship
between the amount of movement of the sensor roller 32 and the
angle .alpha. that the ramp 12 is disposed from vertical.
[0045] One or more parameters may be measured to quantify the
movement of the sensor roller 32. For example, empirical testing
has been performed to measure the correlation between a distance
the top-most media sheet travels when picked by the pick roller 21
and each rotation of the sensor roller 32. A similar correlation
may be made with an amount of time the sensor roller 32
rotates.
[0046] The one or more parameters used to quantify the movement of
the sensor roller 32 may be programmed into the controller 100 when
the image forming device 10 is initially built. In another
embodiment, the parameters are stored in the memory 101. Over a
period of time, the values of the parameters may change. For
example, as the sensor roller 32 wears, the correlation between
rotation of the sensor roller 32 and the distance traveled by the
top-most media sheet may change. Therefore, it may be desirable to
input new values for the parameters. In one embodiment, the new
values are entered into the controller 100 or the memory 101
through the control panel 44. In another embodiment, controller 100
maintains ongoing values that are, periodically updated.
[0047] In one embodiment, the controller 400 controls the input
area according to a process 600 shown in FIG. 7. The controller 100
sends a signal to the pick motor 81 to begin rotating (block 605).
The pick motor 81 rotates the pick roller 21. The pick roller 21
then moves the top-most media sheet from the media stack 13. The
movement of the top-most media sheet drives movement of the sensor
roller 325 which is detected by the sensor detector 35. A signal is
sent from the sensor detector to the controller 100. The controller
100 then keeps track of the amount of movement of the sensor roller
32 (block 610). The pick roller 21 continues to advance the media
sheet towards the media position sensor 39 (block 620). When the
media position sensor 39 is triggered, indicating that the leading
edge of the media sheet has reached the media position sensor 39
(block 615) the controller 100 ascertains the total movement of the
sensor roller 32 (block 625). The controller 100 then determines
the media level based on the total movement of the sensor roller 32
(block 630). The controller 100 may then generate a display on the
control panel 44 indicating the media level (block 635). The
display may, for example, be a graphic or numeric representation of
the media level.
[0048] The above describes methods and devices that rely on the
media sheet sensor 30, 63 positioned relative to the pick mechanism
20, 61 on an opposite side of the pick mechanism pivot, as shown in
FIGS. 1, 3, and 5. In other embodiments, however, the media sheet
sensor 30, 63 may have a different orientation relative to the pick
mechanism pivot. In one embodiment, the media sheet sensor 30, 63
may be positioned on the same side of the pick mechanism pivot, as
shown in FIG. 8.
[0049] Spatially relative terms such as "under", "below", "lower",
"over", "upper", and the like, are used for ease of description to
explain the positioning of one element relative to a second
element. These terms are intended to encompass different
orientations of the device in addition to different orientations
than those depicted in the figures. Further, terms such as "first",
"second", and the like, are also used to describe various elements,
regions, sections, etc and are also not intended to be limiting,
Like terms refer to like elements throughout the description.
[0050] As used herein, the terms "having", "containing",
"including", "comprising" and the like are open ended terms that
indicate the presence of stated elements or features, but do not
preclude additional elements or features. The articles "a", "an"
and "the" are intended to include the plural as well as the
singular, unless the context clearly indicates otherwise.
[0051] The present devices and methods may be carried out in other
specific ways than those herein set forth without departing from
the scope and essential characteristics. The present embodiments
are, therefore, to be considered in all respects as illustrative
and not restrictive, and all changes coming within the meaning and
equivalency range of the appended claims are intended to be
embraced therein.
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