Data processing: measuring – calibrating – or testing – Measurement system – Article count or size distribution
Reexamination Certificate
2000-10-10
2003-09-23
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system
Article count or size distribution
Reexamination Certificate
active
06625561
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an inexpensive method and apparatus for sensing the height of a stack of media sheets, such as paper, used by media-using-machines such as desk top printers, fax machines, and the like, that are sheet fed from a media holder such as an input hopper or tray.
BACKGROUND ART
There are a variety of media-using-machines that are fed from a stack of sheets of media. For example, desktop printers, fax machines, and text scanning machines typically operate in this fashion with the media being paper, plastic for transparencies and so forth. The media stack is held in input hoppers or trays which may be removable or built-in.
FIG. 1
is a perspective view which shows a prior art sheet fed media-using-machine
20
. Machine
20
has a media holder
22
and is fed with media sheets
24
which are held in media holder
22
. In
FIG. 1
, media holder
22
is illustrated as a tray but other embodiments, such as a slot into which a stack of media sheets
24
are directly placed may also be employed. Media holder
22
is inserted into holder slot
26
and is thus housed within or attached to machine
20
. Media holder
22
is illustrated as a removable tray in which media sheets
24
form a media stack. Media sheets
24
move in the direction of arrow
22
A and are fed into media-using-machine
20
. Media sheets are withdrawn sheet-at-a-time (sheetwise) from what is referred to as the top of a stack. Media sheets
24
are processed within machine
20
, such as by printing upon the media or optically scanning the media, and are ejected from media eject opening
28
in the direction of arrow
28
A to be deposited into the pickup hopper location of sheet
24
A. Machine
20
has within it a control system
29
for controlling the operations of machine
20
that are described in this paragraph.
In prior art desktop printers, if the media holder
22
becomes empty such as resulting from normal use of all media sheets
24
that are held in media holder
22
, then control system
29
may cause an audible or visible signal (not shown) on machine
20
to activate. An operator using machine
20
may notice the alert signal, realize that no media sheets
24
remain in media holder
22
and then refill media holder
22
with additional media sheets
24
. Alternatively, or in addition to the foregoing signal, if in the process of printing a print job the printer is depleted of paper, then control system
29
may cause a message to appear on a display, such as a message to the effect “the printer is out of paper, do you wish to continue ( ) yes, or ( ) no?” This message is accompanied by a pause in machine operation since no media sheets
24
remain in media holder
22
. Once the operator has refilled media holder
22
and replaced it in holder slot
26
, the operator may click a computer mouse in the “yes” location and proceed with the print job. Alternatively, the operator may cancel the job. Alternatively, the machine
20
may automatically sense that the media holder
22
is no longer empty and begin to continue a print job.
FIG. 2
is a cut-away view which provides further details of the prior art media holder
22
. In this and in other figures described in this specification, like numerals are identified with like reference numbers. Media holder
22
provides a structure for supporting media sheets
24
, with the structure comprised of tray bottom
30
A which provides a common supporting structure for the sides of media holder
22
. These sides are front side
30
B, right side
30
C, back side
30
D, and left side
30
E (not shown). Media sheets
24
are stacked into media holder
22
with tray bottom
30
A providing vertical support to the sheets and with sides
30
B,
30
C,
30
D, and
30
E providing a structure to retain media sheets
24
stacked in a vertical column of sheets, one atop the another. The front side
30
B is “front” with reference to flow of media sheets
24
from media holder
22
, that is, as media sheets
24
are fed from media stack
24
into the media processing areas of machine
20
, such media sheets
24
flow past front side
30
B. Right side
30
C and left side
30
E are right and left, respectively, with reference to view in the direction of media feed direction, illustrated by arrow
22
A. The back side
30
D is the side that is opposite the front side.
Stack pusher
32
is disposed to provide a mechanical pushing force to push media sheets
24
(the media stack) into a position such that machine
20
may withdraw the sheets from the stack. Stack pusher
32
consists of pusher plate
32
A, pusher base
32
B, hinge
32
C, and spring
32
D. Pusher plate
32
A is pivotally connected by hinge
32
C to pusher base
32
B. Spring
32
D provides a compressive force to urge pusher plate
32
A away from pusher base
32
B. Pusher base
32
B may be attached to tray bottom
30
A, or tray bottom
30
may serve as pusher base
32
B. This urging force of spring
32
D causes pusher plate
32
A to push media sheets
24
into a position that machine
20
may withdraw the sheets from the stack. It should be noted that while the illustration shows spring
32
D pushing pusher plate
32
A, the prior art includes springs disposed to exert tensile force pull to pusher plate
32
A, and the prior art includes rotational forces to torque pusher plate
32
A, all to provide the same result of pushing media stack
24
.
FIG. 3
is a perspective view of the prior art media holder
22
of FIG.
2
. In this view, right side
30
C, back side
30
D, and left side
30
E are attached to tray bottom
30
A. Window
30
F is provided on back side
30
D. Window
30
F is a vacancy or an aperture which is provided to allow a user of machine
20
to determine the presence or absence of media sheets
24
in media holder
22
, or to estimate the number of media sheets
24
in media holder
22
, without the need for withdrawing media holder
22
from holder slot
26
. Thus window
30
F provides a convenient way of ascertaining the amount of media sheets
24
in media holder
22
. A limitation of window
30
F is that it does not provide quantity information to control system
29
. Another limitation of window
30
F is that it requires the active attention of the operator of machine
20
, that is, the operator must pay attention to window
30
F. Yet another limitation is that machine
20
must be positioned or oriented on a desk or table such that the window is easily within view. In practice, when media sheets
24
are fully depleted, machine
20
stops operation. The view provided by window
30
F becomes simply a confirmation of what the operator already expects when machine
20
stops operation, that is, confirmation that media holder
22
is indeed empty with the convenience being that confirmation can be performed without withdrawing media holder
22
from machine
20
for inspection.
FIG. 4
is a perspective view of a prior art media holder
22
with some differences to that illustrated by FIG.
3
. In
FIG. 4
, pusher plate
32
A has tabs
36
A which project into slots
36
B. Slots
36
B are indentations, grooves, or the like, that are built into right side
30
C and left side
30
E. Tabs
36
A and slots
36
B allow pusher plate
32
A to change position in a constrained translational motion fashion in contrast to the rotational motion featured by prior art media holders
22
of
FIGS. 2 and 3
having a hinge
32
C allowing constrained rotational movement of pusher plate
32
A.
FIG. 4
also illustrates indicator mechanism
38
. Indicator mechanism
38
is a mechanism which is provided to allow a user of machine
20
to determine the presence or absence of media sheets
24
in media holder
22
, or to estimate the number of media sheets
24
in media holder
22
, without the need for withdrawing media holder
22
from holder slot
26
. While indicator window
30
F provided a direct viewing means, indicator mechanism
38
provides an indirect way of accomplishing the same result. Indicator mechanism
38
is comprised of indicator lever
38
A having indicator e
Barlow John
Hewlett--Packard Development Company, L.P.
Lau Tung
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