U.S. patent application number 10/649866 was filed with the patent office on 2004-03-04 for sheet feeder.
Invention is credited to Hiraoka, Jun.
Application Number | 20040041329 10/649866 |
Document ID | / |
Family ID | 31972526 |
Filed Date | 2004-03-04 |
United States Patent
Application |
20040041329 |
Kind Code |
A1 |
Hiraoka, Jun |
March 4, 2004 |
Sheet feeder
Abstract
For designing a more compact image reading device and printer
requiring for separating a paper sheet and feeding the separated
sheet, a limited space above a sheet cassette is effectively used
for accommodating a larger number of paper sheets. A sensor lever
is supported at its sensor lever axis fitted in an elliptic hole
made in a supporting member of the sensor lever. The axis can swing
and slide in the elliptic hole. With a large number of sheets piled
in the cassette, the sensor lever swings to about horizontal
position and the axis retracts up in the elliptic hole. With a
small number of sheets, the sensor lever abuts at its abutting
member against a receiving portion of the supporting member to
prevent the sensor lever axis from moving upward in the elliptic
hole, thereby the sensor lever can reliably detect the state of no
paper remaining thereon.
Inventors: |
Hiraoka, Jun; (Shiki-gun,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
31972526 |
Appl. No.: |
10/649866 |
Filed: |
August 28, 2003 |
Current U.S.
Class: |
271/110 |
Current CPC
Class: |
B65H 2511/30 20130101;
B65H 2553/612 20130101; B65H 2511/30 20130101; B65H 2511/212
20130101; B65H 7/04 20130101; B65H 2220/01 20130101; B65H 2220/03
20130101; B65H 2220/11 20130101; B65H 2511/212 20130101 |
Class at
Publication: |
271/110 |
International
Class: |
B65H 007/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 28, 2002 |
JP |
2002-248565 |
Claims
1. A sheet feeder for separating one of paper sheets piled thereon
and feeding the separated sheet to a next process, wherein a sensor
lever abutting against the top of sheets piled swings with a
swinging axis and changes its angle in accordance with the amount
of sheets and when a large number of sheets are loaded the swinging
axis moves upward together with the sensor lever in the direction
of separating the sensor lever from the pile of sheets.
2. A sheet feeder as defined in claim 1, wherein a supporting
member for supporting the sensor lever has an elliptic hole made
for fitting therein the swinging axis of the sensor lever and the
sensor lever has a abutting member formed thereon for abutting
against a receiving portion of the supporting member to prevent the
swinging axis of the sensor lever from moving when working with a
decreased amount of sheets piled or with no sheet.
3. A sheet feeder as defined in claim 1, wherein a supporting
member for supporting the sensor lever has an elliptic hole having
an enlarged round hole made for fitting therein the swinging axis
of the sensor lever and the swinging axis of the sensor lever has a
noncircular section to prevent the swinging axis of the sensor
lever from moving in the elliptic hole when working with a
decreased amount of sheets piled or with no sheet.
4. A sheet feeder as defined in any of claims 2 and 3, wherein a
sheet piling portion has a concave formed thereon and a lower tip
of the sensor lever falls in the concave with no sheet on the sheet
piling portion.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a sheet feeder for holding
a plurality of paper sheets and feeding individual sheets one by
one to an image reading device, printer or the like. Specifically,
it relates to a sheet feeder provided with a sheet sensor for
detecting the absence/existence of a sheet and the width of a sheet
by sensing a change of a swing angle of a sensor lever.
[0002] Particularly in image reading devices or printers,
separating a paper sheet from a pile of sheets loaded in a sheet
feeding portion and feeding it to a next process is a very
important technique which therefore has been implemented by using a
various well-known structures and arrangements of printers etc.
[0003] There are various kinds of methods for separating a paper
sheet from a plurality of sheets, e.g., by using a combination of a
feeding roller and a reverse rotating roller or a combination of a
feeding roller and a separating nail or a combination of a feeding
roller and a separating plate or vacuum suckers.
[0004] A method using a rotary (swinging) lever for discriminating
the size of a paper sheet and the existence/absence of a paper
sheet is also known. Specifically, this conventional method has
been implemented in such a manner that the swinging lever can take
refuge in an opening made on a sheet supporting table to widen the
swinging range of the swinging lever in order to increase the
detection ability of the swinging lever.
[0005] In recent years, there has been seen the tendency of
miniaturization of image forming apparatuses such as image reading
devices and printers which in turn have a tendency that a number of
loaded paper sheets increases, then the capability of loading a
larger number of paper sheets in a smaller space becomes an
important designing element ensuring separation and transportation
of an individual paper sheet. Consequently, saving in the physical
space for mounting a sheet sensor has become an important problem
to be solved.
SUMMARY OF THE INVENTION
[0006] An object of the present invention is to provide a sheet
feeder capable of causing a conventional sensor lever to swing in
accordance with an amount of sheets loaded in a sheet cassette and
detecting the amount of the sheets based on a change in a swing
angle of the sensor lever, wherein a bottom board for supporting a
pile of sheets has a notch for receiving the sensor lever so that
the sensor lever can surely detect the existence/absence of the
paper by increasing a changing amount of the swing angle of the
sensor lever before and after the last sheet is fed. In this
instance, it is difficult to achieve a sufficient sheet holding
capacity since the maximum amount of sheets loaded on the bottom
board may be restricted by a distance between a surface of the
bottom board and the supporting axis of the sensor lever.
[0007] Therefore, the sheet feeder according to the present
invention can load an increased amount of sheets by enabling the
sensor lever to swing for loading a larger number of sheets in the
sheet cassette and, when an amount of sheets increases, retracting
the sensor lever from the pile of sheets. On the contrary, with a
small amount of remaining sheets, the sensor lever is prevented
from retracting never to fail in detecting the state of no
remaining sheet in the sheet cassette.
[0008] Another object of the present invention is to provide a
sheet feeder separating a sheet from a pile of sheets loaded in a
sheet cassette and feeding it to a next process, wherein a sensor
lever abuts against a top of a pile of sheets in the sheet cassette
and swings with a swinging axis and changes its angle in accordance
with an amount of sheets loaded in the sheet cassette, and when a
large number of sheets are loaded in the sheet cassette the
swinging axis can move upward together with the sensor lever in the
direction of separating the sensor lever from the pile of sheets.
This makes it possible to increase the maximum number of sheets to
be loaded by using space efficiently when designing a compact image
reading device or printer which needs to ensure separation and
transportation of a sheet.
[0009] Another object of the present invention is to provide a
sheet feeder as described above, wherein a sensor lever is
supported at its swinging axis in an elliptic hole made in a
supporting member and has an abutting member which may abut against
the receiving portion of the supporting member to prevent the
swinging axis of the sensor lever from moving with a small amount
or no amount of sheets. This simple means enables the sheet feeder
to surely prevent the movement of the swinging axis of the sensor
lever, ensuring the reliable operation of the sensor lever with a
small amount of remaining sheets to be fed.
[0010] A further object of the present invention is to provide a
sheet feeder as described above, wherein a sensor lever is
supported at its swinging axis with a noncircular cross-section
inserted in an elliptic hole with an enlarged round portion made in
the supporting member to prevent the movement of the swinging axis
in the elliptic hole of the supporting member with a small amount
or no amount of sheets, thereby ensuring the reliable operation of
the sensor lever with a small amount of remaining sheets in the
cassettes.
[0011] A still further object of the present invention is to
provide a sheet feeder as described above, wherein a lower tip of
the sensor lever can fall into a concave formed in a sheet piling
portion to increase the rotation angle of the sensor lever before
and after the last sheet is fed, thereby ensuring the reliable
detection of the existence/absence of the sheets.
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a schematic sectional view of a laser facsimile
apparatus using a sheet feeder according to the present
invention.
[0013] FIG. 2 is a perspective view of a sheet cassette used in the
laser facsimile apparatus.
[0014] FIGS. 3A, 3B and 3C are sectional side views for explaining
the operation of the sheet cassette.
[0015] FIG. 4 is a side view of the first example of a sheet sensor
used in a sheet feeder according to the present invention.
[0016] FIG. 5 is a side view of the second example of a sheet
sensor used in a sheet feeder according to the present
invention.
PREFERRED EMBODIMENTS OF THE INVENTION
[0017] A sheet feeder according to the present invention is to
separate a sheet from a sheet pile and feed it to a next processing
portion and is applied for an image reading device in which
document sheets piled are picked up one by one, scanned by a
document reading device and then delivered out, or an image forming
device, for example, a printer wherein cut-sheets are picked up one
by one, printed by a printing portion and then delivered out. The
following example is the case of using a sheet feeder according to
the present invention in a laser facsimile apparatus using the
Carlson process.
[0018] FIG. 1 schematically illustrates in cross section a laser
facsimile apparatus using a sheet feeder according to the present
invention, where electronic circuits etc. which do not directly
relate to the present invention are omitted for simplicity. In the
laser facsimile apparatus, a control portion 1 is a man-machine
interface portion having various kinds of key buttons for inputting
information by a user and a display for presenting information to a
user.
[0019] A plurality of documents to be read are loaded on a document
feeding portion 2 and separated one by one by a separating rubber
plate 4 disposed opposite to a separator roller 3 and fed to a
document reading unit 5 by which it is read and then delivered by a
document delivering rollers 6 to a document discharging portion 7
where a document stacker (not shown in FIG. 1) is provided for
receiving documents delivered.
[0020] A pile of sheets (recording paper) S are loaded in a sheet
cassette 11 wherefrom one sheet is separated and fed by a pickup
roller 12 (to be described later) to an image transferring portion
19 where toner from a light-sensitive drum 14 is transferred on the
sheet S and forms a visible image on the sheet S. The sheet
carrying a toner-developed image is then heated by a fixing roller
21 for fusing and fixing toner which forms the image on the sheet
S. The sheet S is transported along a document transporting route
20 through the fixing roller 21 to a delivery stacker 22. For
simplicity, some of the sheet guides disposed along the document
transporting route 20 for transporting a sheet S are not shown in
FIG. 1.
[0021] Printing the sheet S is carried out as follows:
[0022] Laser beam L from a laser unit 16 transfers image on the
light-sensitive drum 14 previously electrically charged by a
charging portion 15. Laser beam L is modulated with information to
be printed and converted by a polygon mirror (not shown) to a
scanning beam which beam is then reflected from a reflecting mirror
17 and scan the electrically charged surface of the light-sensitive
drum 14 to form a latent electrostatic image thereon to be
transferred later on a recording paper sheet. Namely, the scanning
laser beam L carries thereon an on-off imaging pattern necessary
for forming an image to be printed and the drum electrically
charged in advance by the charging portion 15 is scanned by the
laser beam L becomes to have decreased potentials of exposed parts
on its surface in accordance with the scanning pattern, resulting
in forming a latent electrostatic image to be printed on the
light-sensitive drum 14. The latent electrostatic image formed on
the light-sensitive drum 14 is developed with toner picked up from
a developing bath 18 to present a visible image which is then
transferred onto a sheet S by an image transfer portion 19. A
sensor lever according to the present invention is applied as a
sheet sensor for a pile of sheets S loaded in a sheet cassette 11
of the shown laser facsimile apparatus.
[0023] FIG. 2 is a perspective view of a sheet cassette used in a
laser facsimile apparatus. Sheets are piled on a bottom board 23 of
the sheet cassette 11, which board is supported at one end by a
supporting shaft 25 and can be lifted by a force of a spring 26
(see FIGS. 3A, 3B and 3C). The front edge of the top of the sheet
pile is prevented from being lifted by a pair of sheet limiting
fingers 27. Namely, the top of the sheet pile is always pressed by
the sheet limiting fingers 27.
[0024] When a pickup roller 12 starts rotation and pushes the top
sheet by the friction force produced there between, then only the
top sheet is fed forward (to right in FIG. 2) overcoming the
preventing force of the sheet limiting fingers 27. Namely, owing to
the fact that a friction force produced between the pickup roller
12 and a top sheet is greater than a total of a preventive force of
the sheet limiting fingers 27 and a friction force produced between
a top sheet and the next sheet, only the top sheet can be separated
and fed from the cassette to a next process.
[0025] When the last sheet S was fed from the sheet cassette 11
shown in FIG. 2, i.e., no paper exist on the bottom board 23 of the
sheet cassette 11, a (front) lower tip 34a of a sensor lever 34
falls into a concave (i.e., "sensor lever receiving port") 24
formed on the bottom board 23 with a large change in swing angle,
which is detected to indicate the absence of the sheet S in the
sheet cassette 11. The provision of the sensor lever receiving port
24 can produce a greater change in swing angle of the sensor lever
34 before and after the last sheet S disappears from the sheet
cassette 11, thereby making it possible to surely detect the state
of no paper existing in the sheet cassette 11. A change in a swing
angle of the sensor lever 34 can be detected by using a suitable
sensor element such as a micro-switch, reed switch, electromagnetic
sensor, photo coupler and so on. A linear arrangement of plural
micro-switches for detecting an angle of the sensor lever 34 is
effective to indicate an approximate amount of recording sheets
remaining in the sheet cassette 11.
[0026] FIGS. 3A, 3B and 3C are sectional side elevations for
explaining the operation of the sheet cassette. FIG. 3A shows the
sheet cassette loaded with a sufficient amount of sheets, FIG. 3B
shows the sheet cassette with a small amount of sheets therein and
FIG. 3C shows the sheet cassette with no paper therein.
[0027] In FIG. 3A, the sheet cassette 11 is full loaded with paper
sheets S on the top of which a sensor lever 34 lies taking an
approximate horizontal angular position. In this state, a whole
sensor lever 34 with its swinging axis (sensor lever axis) 35 is
lifted upward by the effect of technical means (to be described
later) to increase the number of sheets to be loaded in the sheet
cassette 11.
[0028] FIG. 3B illustrates the state of the sheet cassette 11
containing a small amount of paper sheets S in which the bottom
board 23 supported by the supporting shaft 25 is tilted with its
front end lifted on the side of the pickup roller 12. In this
state, the top of paper sheets abuts against the sheet limiting
fingers 27 and the function of separating a top sheet and feeding
it by the pickup roller 12 still remains in ready to operate. The
lower tip 34a of the sensor lever 34 moved downward from the
position shown in FIG. 3A. However, a detection signal "no paper"
cannot be generated in this state of the sensor lever 34.
[0029] When the last sheet was fed from the sheet cassette 11, the
sensor lever 34 falls into the sensor lever receiving port 24
formed on the bottom board as shown in FIG. 3C. In this state, the
lower tip 34a of the sensor lever 34 dropped by a considerable
angle, which can be easily detected to indicate the absence of
paper in the sheet cassette 11.
[0030] FIG. 4 illustrates a side view of the first example of a
sheet sensor used in the sheet feeder according to the present
invention. A sensor lever 34 has a sensor lever axis (swinging
axis) 35 fitted in an elliptic hole 32 made in a sensor lever
holding member 31 for the sensor lever and can freely swing. A
sensor lever holding member 31 corresponds to a supporting member
defined in claims. The sensor lever 34 locates at the lowest part
of the elliptic hole 32 by its weight. The sensor lever 34 has a
sensor lever abutting member 36 and the sensor lever holding member
31 has a sensor lever receiving member 33. With a small amount of
sheets in the cassette as shown FIG. 4, the sensor lever 34 swings
and the sensor lever abutting member 36 abuts against the sensor
lever receiving member 33 of the sensor lever holding member 31. In
this state, the sensor lever axis 35 cannot move upward in the
elliptic hole 32. As described above, when the number of sheets in
the sheet cassette is small, the sensor lever axis 35 is prevented
from moving upward in the elliptic hole 32 by abutting the sensor
lever abutting member 36 against the sensor lever receiving member
33. A change in angular position of the sensor lever 34 is
correctly detected to indicate the existence/absence of a paper
sheet in the cassette.
[0031] FIG. 5 illustrates a side view of the second example of a
sheet sensor usable in a sheet feeder according to the present
invention.
[0032] The sensor lever 43 has a sensor lever axis 44 movably
fitted in an elliptic hole 42 made in a sensor lever holding member
41 for the sensor lever. The sensor lever axis 44 has a noncircular
section of different sizes in radial directions. In the shown
instance, the sensor lever axis 44 with an elliptic cross-section
can or cannot move in the elliptic hole in the holding member
depending on an angle of the sensor lever 43. On the other hand,
the elliptic hole 42 made in the holding member 41 has a larger
diameter round hole 42a in its lower end of the elliptic hole 42.
Therefore, the sensor lever axis 44 can freely rotate in the larger
round hole 42a at any angle of the sensor lever 43. When the sensor
lever 43 takes a near horizontal position in FIG. 5, the sensor
lever axis 44 can move upward in the upper portion of the elliptic
hole 42 since the direction of the longest diameter of the sensor
lever axis 44 is identical to the longitudinal direction of the
elliptic hole 42 of the sensor lever holding member 41.
[0033] This sheet sensor can retract the sensor lever 43 upward by
moving the sensor lever axis upward in the elliptic hole 42 when
the sheet cassette is loaded with a large number of paper sheets.
On the other hand, the sheet sensor keeps the sensor lever axis 44
in the large round hole 42a when the sensor lever 43 works with a
reduced amount of sheets in the sheet cassette, reliably sensing
the existence/absence of paper sheets to be fed.
[0034] While the present invention has been described by way of
examples with the case that a sheet cassette is provided with a
sheet sensor for sensing the existence/absence of paper sheets and
an approximate amount of sheets remaining in the sheet cassette, it
is also possible to discriminate the sizes of paper sheets to be
used by arranging a plurality of sensors in width direction of the
sheet cassette in accordance with different format sizes of paper
sheets to be accommodated therein.
[0035] While the invention has been described with the application
of the sheet feeder to a facsimile apparatus, image reading device,
and printer, the sheet feeder can be also applied to any of other
devices requiring feeding paper sheets from a pile of sheets and,
therefore, the scope of the claims is not limited to the described
applications and embodiments.
[0036] A sheet feeder according to the present invention is a
compact structure and capable of accommodating a large number of
paper sheets in the sheet cassette by swinging the sensor lever and
retracting the sensor lever upward with its swinging axis moved in
the direction parting from the top of sheets when a large amount of
sheets are loaded in the sheet cassette, and making the movement of
sensor lever reliable which detects the existence/absence of a
paper sheet by the sensor lever.
[0037] With a small amount or no amount of sheets remaining in the
sheet cassette, the abutting member is formed on the sensor lever
and abuts against a receiving member of the supporting member,
thereby preventing the movement of the swinging axis in a simple
structure and enabling the movement of the sensor lever to be
reliable.
[0038] The sensor lever has a swinging axis of a noncircular
profile, which axis is fitted in an elliptic hole with an enlarged
round hole formed in the supporting member. With a small amount or
no amount of paper sheets remaining in the sheet cassette, the
swinging axis is kept in the enlarged round hole in order to ensure
the reliable action of the sensor lever with decreasing amount of
the remaining sheets.
[0039] When the last sheet was fed from the sheet cassette, a lower
tip of the sensor lever falls into a concave formed in the bottom
board of the sheet cassette. This can provide a considerable change
in swinging angle of the sensor lever before and after the last
sheet is fed, which can be surely detected to indicate whether the
last paper remains or not.
* * * * *