U.S. patent application number 12/985482 was filed with the patent office on 2011-07-14 for paper feeding device and image forming apparatus having the same and control method thereof.
This patent application is currently assigned to Samsung Electronics Co., Ltd. Invention is credited to Ju Hwan JEONG, Jong Cheol OH, Dong Chul YANG.
Application Number | 20110169215 12/985482 |
Document ID | / |
Family ID | 44257934 |
Filed Date | 2011-07-14 |
United States Patent
Application |
20110169215 |
Kind Code |
A1 |
OH; Jong Cheol ; et
al. |
July 14, 2011 |
PAPER FEEDING DEVICE AND IMAGE FORMING APPARATUS HAVING THE SAME
AND CONTROL METHOD THEREOF
Abstract
A paper feeding device to sense various sizes of paper according
to a sensing voltage output from a sensor and an image forming
apparatus having the same includes a body to receive paper in which
an image is printed thereon. The image forming apparatus further
includes a paper feeding device to feed paper into the body. The
paper feeding device includes a paper tray in which paper is
loaded, and paper guides that are slidably installed to the paper
tray to guide left and right ends of paper loaded in the paper tray
in a paper feeding direction. A light reflector is installed to be
moved in linkage with the paper guides and includes a stepped
reflection surface. A sensor emits light to the light reflector and
receives the light reflected by the light reflector to determine
the sizes of paper.
Inventors: |
OH; Jong Cheol; (Suwon-si,
KR) ; YANG; Dong Chul; (Suwon-si, KR) ; JEONG;
Ju Hwan; (Suwon-si, KR) |
Assignee: |
Samsung Electronics Co.,
Ltd
Suwon-si
KR
|
Family ID: |
44257934 |
Appl. No.: |
12/985482 |
Filed: |
January 6, 2011 |
Current U.S.
Class: |
271/227 ;
271/171; 271/265.01 |
Current CPC
Class: |
B65H 2511/10 20130101;
B65H 2511/22 20130101; B65H 1/266 20130101; B65H 2515/702 20130101;
B65H 2220/02 20130101; B65H 2553/414 20130101; B65H 2511/10
20130101; B65H 2511/22 20130101; B65H 7/14 20130101; B65H 2515/702
20130101; B65H 2220/03 20130101; B65H 2220/01 20130101 |
Class at
Publication: |
271/227 ;
271/265.01; 271/171 |
International
Class: |
B65H 7/02 20060101
B65H007/02; B65H 7/20 20060101 B65H007/20; B65H 1/00 20060101
B65H001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 8, 2010 |
KR |
2010-1994 |
Claims
1. A paper feeding device comprising: a paper tray in which paper
is loaded; at least one paper guide adjustable in a plurality of
positions according to a width of the paper to guide a left or
right end of the paper loaded in the paper tray in a paper feeding
direction; a light reflector installed to be moved in linkage with
the paper guide and having a stepped reflection surface; and a
sensor that emits light to the light reflector and receives the
light reflected by the light reflector and outputs a sensing
voltage corresponding to the received light, to enable calculation
of a size of the paper.
2. The paper feeding device according to claim 1, wherein: the at
least one paper guide includes a pair of paper guides to guide the
left and right ends of the paper in the paper feeding direction;
and the paper feeding device further comprises first and second
racks connected respectively to the pair of paper guides to allow
the pair of paper guides to be moved in linkage with each other,
and a pinion gear-engaged with the first and second racks.
3. The paper feeding device according to claim 2, wherein the light
reflector is coupled to at least one of the first rack and the
second rack and is moved in linkage with the paper guides.
4. The paper feeding device according to claim 3, wherein the light
reflector is one of injection-molded or assembled to one of the
first rack and the second rack.
5. The paper feeding device according to claim 1, wherein: the
sensor includes a light emitting element to emit light and a light
receiving element to receive the light; and the light emitting
element and the light receiving element are one of integrally
formed with each other or are separated from each other.
6. An image forming apparatus comprising: a body in which an image
is printed on paper; at least one paper tray to support paper i;
and a paper feeding device comprising: at least one paper guide
that guides a left or right end of the paper loaded in the paper
tray in a paper feeding direction, wherein a position of the paper
guide being adjusted according to a width of the paper; and a light
reflector installed to be moved in linkage with the paper guide and
having a stepped reflection surface; a sensor that emits light to
the light reflector and receives the light reflected by the light
reflector; and a controller that calculates a size of the paper
according to a sensing voltage output from the sensor.
7. The image forming apparatus according to claim 6, wherein: the
at least one paper guide includes a pair of paper guides to guide
the left and right ends of the paper in the paper feeding
direction; and the paper feeding device further includes first and
second racks connected respectively to the pair of paper guides to
allow the pair of paper guides to be moved in linkage with each
other, and a pinion gear-engaged with the first and second
racks.
8. The image forming apparatus according to claim 7, wherein the
light reflector is coupled to one of the first rack and the second
rack and is moved in linkage with the paper guides.
9. The image forming apparatus according to claim 8, wherein the
light reflector is one of injection-molded or assembled to one of
the first rack and the second rack.
10. The image forming apparatus according to claim 6, wherein: the
sensor includes a light emitting element to emit light and a light
receiving element to receive the light; and the light emitting
element and the light receiving element are one of integrally
formed with each other or are separated from each other.
11. The image forming apparatus according to claim 6, wherein the
at least one paper tray includes at least one first paper tray
pivotally rotatably coupled to the body and at least one second
paper tray inserted into the body in a drawer manner.
12. A method of determining a paper size of paper in an image
forming apparatus comprising: confirming whether or not paper is
loaded in at least one paper tray; emitting light to a light
reflector if the paper is loaded in the paper tray, the light
reflector being moved in linkage with a paper guide installed to
the paper tray and having a stepped reflection surface; detecting a
size of the paper according to a magnitude of a sensing voltage if
a sensor installed at a side of the paper tray outputs the sensing
voltage corresponding to the quantity of light reflected by the
reflection surface; and performing a printing operation according
to the detected paper size.
13. The control method according to claim 12, wherein: the at least
one paper tray includes at least one first paper tray pivotally
rotatably coupled to the body and at least one second tray inserted
into the body in a drawer manner; and the confirming whether or not
paper is loaded further comprises confirming that paper is newly
loaded into the at least one first paper tray when paper inside the
at least one first paper tray is detected subsequent to confirming
paper was not loaded and confirming that paper is newly loaded into
the at least one second paper tray when the second paper tray is
separated and thereafter is reinstalled.
14. A paper tray to receive paper, comprising; at least one paper
guide that is adjustable according to a width of the paper; a light
reflector having a reflective portion to reflect light and coupled
to the at least one paper guide to be moved in linkage with the
paper guide; and a sensor that emits light to the light reflector
and receives the light reflected by the light reflector and outputs
a sensing voltage corresponding to the received light.
15. The paper tray of claim 14, wherein the reflective portion is
formed to reflect light at a plurality of distances different from
one another based on an area of the reflective portion that
reflects the light.
16. The paper tray of claim 15 wherein the reflective surface
includes a plurality of reflective surface disposed in a step-like
manner from one end of the light reflector to an opposite end of
the light reflector such that distance between each reflective
surface and the sensor defines a reflective distance between the
light reflector and the sensor.
17. The paper tray of claim 14 further comprising a rack unit
connected to the paper guide to move in a width direction of the
paper wherein the light reflector moves together with the rack unit
in the width direction.
18. The paper tray of claim 14 wherein the reflector is disposed in
a width direction of the paper and the sensor emits light in a
direction horizontal to the width direction.
19. The paper tray of claim 14, wherein the reflector has a pattern
representing paper sizes and the sensor and the reflector are
arranged in a length direction of the paper direction.
20. A paper tray to receive paper, comprising; first and second
paper guides that are adjustable according to a width of the paper
to center the paper along a center axis of the paper tray extending
in a paper feed direction; a light emitting element that emits
light along a light path following the center axis of the paper
tray; a light reflector moveable into the light path in response to
adjusting the first and second paper guides to reflect emitted
light; and a light receiving element that receives the reflected
emitted light from the light reflector and outputs a sensing
voltage corresponding to the received light.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C.
.sctn.119(a) from Korean Patent Application No. 2010-0001994, filed
on Jan. 8, 2010 in the Korean Intellectual Property Office, the
disclosure of which is incorporated herein by reference.
BACKGROUND
[0002] 1. Field of the Invention
[0003] Embodiments of the present general inventive concept relate
to a paper feeding device functioning to sense a paper size and an
image forming apparatus having the same and a control method
thereof.
[0004] 2. Description of the Related Art
[0005] Generally, image forming apparatuses, such as copiers,
printers and fax machines, include a paper feeding device in which
a plurality of sheets of paper is received, the paper feeding
device serving to sequentially feed the received paper into a body
of an image forming apparatus.
[0006] The paper feeding device includes a paper tray in which
paper is loaded, and paper guides arranged to come into contact
with both ends of loaded paper so as to guide the paper in a paper
feeding direction. The paper guides are slidably coupled to the
paper tray to accommodate various sizes of paper. An image forming
apparatus is generally connected to a computer. The computer
designates the size of paper, on which an image edited by the
computer will printed. The image forming apparatus receives
information related to the designated paper size and prepares a
printing operation corresponding to the designated paper size. If
the size of paper loaded in the paper tray is inconsistent with the
designated paper size, this causes printing defects. To prevent
printing defects due to inconsistent paper size, a device to sense
the size of paper loaded in the paper tray may be provided. There
are various paper sizes of A4, A3, B5, B4, letter and other user
designated sizes, and a photo sensor may be used to sense the size
of a paper. To sense an arbitrary paper size value between an
allowable upper limit and an allowable lower limit of a specific
image forming apparatus, it may be necessary to install photo
sensors on a per paper size basis. This increases manufacturing
costs in proportion to the number of photo sensors and is
uneconomical.
SUMMARY
[0007] Therefore, it is an feature of the present general inventive
concept to provide a paper feeding device which may sense the size
of paper according to a sensing voltage output from a single sensor
and an image forming apparatus having the same and a control method
thereof.
[0008] Additional features of the present general inventive concept
will be set forth in part in the description which follows and, in
part, will be obvious from the description, or may be learned by
practice of the general inventive concept.
[0009] In accordance with one feature of the present general
inventive concept, a paper feeding device includes a paper tray in
which paper is loaded, at least one paper guide that guides a left
or right end of the paper loaded in the paper tray in a paper
feeding direction, a position of the paper guide being adjusted
according to a width of the paper, a light reflector installed to
be moved in linkage with the paper guide and having a stepped
reflection surface, and a sensor that emits light to the light
reflector and receives the light reflected by the light reflector
and outputs a sensing voltage corresponding to the received light,
to enable calculation of a size of the paper.
[0010] The at least one paper guide may include a pair of paper
guides to guide the left and right ends of the paper in the paper
feeding direction, and the paper feeding device may further include
first and second racks connected respectively to the pair of paper
guides to allow the pair of paper guides to be moved in linkage
with each other, and a pinion gear-engaged with the first and
second racks.
[0011] The light reflector may be coupled to one of the first rack
and the second rack and may be moved in linkage with the paper
guides.
[0012] The light reflector may be injection-molded or assembled to
one of the first rack and the second rack.
[0013] The sensor may include a light emitting element to emit
light and a light receiving element to receive the light, and the
light emitting element and the light receiving element may be
integrally formed with each other or may be separated from each
other.
[0014] In accordance with another feature of the present general
inventive concept, an image forming apparatus includes a body in
which an image is printed on paper, at least one paper tray in
which the paper is loaded, and a paper feeding device including at
least one paper guide that guides a left or right end of the paper
loaded in the paper tray in a paper feeding direction, a position
of the paper guide being adjusted according to a width of the
paper, a light reflector installed to be moved in linkage with the
paper guide and having a stepped reflection surface, a sensor that
emits light to the light reflector and receives the light reflected
by the light reflector, and a controller that calculates a size of
the paper according to a sensing voltage output from the
sensor.
[0015] The at least one paper guide may include a pair of paper
guides to guide the left and right ends of the paper in the paper
feeding direction, and the paper feeding device may further include
first and second racks connected respectively to the pair of paper
guides to allow the pair of paper guides to be moved in linkage
with each other, and a pinion gear-engaged with the first and
second racks.
[0016] The light reflector may be coupled to one of the first rack
and the second rack and may be moved in linkage with the paper
guides.
[0017] The light reflector may be injection-molded or assembled to
one of the first rack and the second rack.
[0018] The sensor may include a light emitting element to emit
light and a light receiving element to receive the light, and the
light emitting element and the light receiving element may be
integrally formed with each other or are separated from each
other.
[0019] The at least one paper tray may include one or more of a
first paper tray pivotally rotatably coupled to the body and a
second paper tray inserted into the body in a drawer manner.
[0020] In a further feature of the present general inventive
concept, a control method of an image forming apparatus includes
confirming whether or not paper is loaded in at least one paper
tray, emitting light to a light reflector if the paper is loaded in
the paper tray, the light reflector being moved in linkage with a
paper guide installed to the paper tray and having a stepped
reflection surface, detecting a size of the paper according to a
magnitude of a sensing voltage if a sensor installed at a side of
the paper tray outputs the sensing voltage corresponding to the
quantity of light reflected by the reflection surface, and
performing a printing operation according to the detected paper
size.
[0021] The at least one paper tray may include one or more of a
first paper tray pivotally rotatably coupled to the body and a
second tray inserted into the body in a drawer manner, and the
control method may further include confirming that paper is newly
loaded into the paper tray if paper inside the first paper tray is
not initially detected, but is detected later, or if the second
paper tray is separated and thereafter, is reinstalled.
[0022] A paper tray to receive paper, comprising at least one paper
guide that is adjustable according to a width of the paper, a light
reflector having a reflective portion to reflect light and coupled
to the at least one paper guide to be moved in linkage with the
paper guide, and a sensor that emits light to the light reflector
and receives the light reflected by the light reflector and outputs
a sensing voltage corresponding to the received light.
[0023] A paper tray to receive paper, comprising first and second
paper guides that are adjustable according to a width of the paper
to center the paper along a center axis of the paper tray extending
in a paper feed direction, a light emitting element that emits
light along a light path following the center axis of the paper
tray, a light reflector moveable into the light path in response to
adjusting the first and second paper guides to reflect emitted
light, and a light receiving element that receives the reflected
emitted light from the light reflector and outputs a sensing
voltage corresponding to the received light.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] These and/or other features of the present general inventive
concept will become apparent and more readily appreciated from the
following description of the embodiments, taken in conjunction with
the accompanying drawings of which:
[0025] FIG. 1 is a perspective view illustrating an image forming
apparatus having a paper feeding device according to an embodiment
of the present general inventive concept;
[0026] FIG. 2 is a perspective view schematically illustrating
paper guides and a sensor provided at a first paper tray of the
paper feeding device according to an embodiment;
[0027] FIG. 3 is a perspective view schematically illustrating
paper guides and a sensor provided at a second paper tray of the
paper feeding device according to an embodiment;
[0028] FIG. 4 is a partially enlarged view illustrating a rear
surface of the paper tray of the paper feeding device according to
an embodiment;
[0029] FIG. 5 is a graph illustrating an output voltage of a light
receiving element corresponding to a distance between a sensor and
a light reflector provided in the paper feeding device according to
an embodiment;
[0030] FIG. 6 is a control block diagram of the image forming
apparatus according to an embodiment; and
[0031] FIG. 7 is a control flow chart of the image forming
apparatus according to an embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0032] Reference will now be made in detail to the embodiments of
the present general inventive concept, examples of which are
illustrated in the accompanying drawings, wherein like reference
numerals refer to like elements throughout. The embodiments are
described below in order to explain the present general inventive
concept by referring to the figures.
[0033] FIG. 1 is a perspective view illustrating an image forming
apparatus having a paper feeding device according to an embodiment
of the present general inventive concept, FIG. 2 is a perspective
view schematically illustrating paper guides and a sensor provided
at a first paper tray of the paper feeding device according to an
embodiment, and FIG. 3 is a perspective view schematically
illustrating paper guides and a sensor provided at a second paper
tray of the paper feeding device according to an embodiment.
[0034] FIG. 4 is a partially enlarged view illustrating a rear
surface of the paper tray of the paper feeding device according to
an embodiment, and FIG. 5 is a graph illustrating an output voltage
of a light receiving element corresponding to a distance between a
sensor and a light reflector provided in the paper feeding device
according to an embodiment.
[0035] Referring to FIG. 1, the image forming apparatus includes a
body 100 in which an image is printed on paper P, and a paper
feeding device to feed the paper P into the body 100. The body 100
may be realized in an electro-photographic manner or ink-jet manner
according to various embodiments. In the embodiment of FIG. 1, the
paper P is fed from the bottom of the image forming apparatus and
after an image is printed on the paper P inside the body 100, the
printed paper P is discharged via a discharge device provided at
the top of the image forming apparatus.
[0036] The paper feeding device includes paper trays 120 and 220 in
which the paper P to be fed is loaded, a pair of paper guides 110a
and 110b and a pair of paper guides 210a and 210b provided
respectively at the paper trays 120 and 220 to center the paper
about a center axis (A) of the paper tray 120 and 220 extending in
a paper feed direction and to guide left and right ends of the
paper P loaded in the paper trays 120 and 220 in the paper feeding
direction. Sensors 150 and 250 are included with the paper tray 120
and 220 to sense the size of the paper P loaded in the paper tray
120 and 220 by sensing positions of the paper guides 110a, 110b,
210a and 210b, as discussed in greater detail below.
[0037] The paper trays 120 and 220 include a first paper tray 120
pivotally rotatably coupled to the body 100 of the image forming
apparatus, and a second paper tray 220 slidably inserted into the
body 100 of the image forming apparatus in a drawer manner. Various
sizes of paper P may be placed on the first paper tray 120 so that
both lateral ends of the paper P come into contact with and are
supported by the paper guides 110a and 110b. The first paper tray
120 is a multi-purpose tray. The second paper tray 220 takes the
form of a paper cassette to be inserted into or separated from the
image forming apparatus, and a plurality of sheets of paper P
having a specific size is loaded in the second paper tray 220. If
necessary, a plurality of first paper trays 120 and a plurality of
second paper trays 220 may be installed. Also, any one or both of
the first paper tray 120 and the second paper tray 220 may be
provided.
[0038] As illustrated in FIG. 2, the first paper tray 120 includes
the pair of paper guides 110a and 110b, first and second racks 111a
and 111b and a pinion 115 to link the left and right paper guides
110a and 110b to each other. The paper tray 120 further includes a
light reflector 112 coupled to and moved in linkage with at least
one of the first and second racks 111a and 111b. The light
reflector 112 further includes a reflective portion 114 to reflect
light directed thereon. The sensor 150 may emit light emit light,
including but not limited to laser light, to generate a light path
extending along the center axis (A) of the paper tray 120 to the
light reflector 112. Accordingly, as the light reflector 112 moves
laterally and across the direction of the light path, the
reflection portion 114 reflects the emitted light back to the
sensor 150 such that the sensor 150 may measure a quantity of
reflected light.
[0039] The paper guides 110a and 110b are connected respectively to
distal ends of the first and second racks 111a and 111b so as to
come into close contact with both lateral ends of the paper during
movement of the first and second racks 111a and 111b. A user may
adjust a distance between the paper guides 110a and 110b according
to a corresponding paper size.
[0040] The light reflector 112 is coupled to at least one of the
first rack 111a and the second rack 111b. The light reflector 112
may be coupled to the first rack 111a and the second rack 111b via
injection molding, or may be previously fabricated and assembled to
the first rack 111a or the second rack 111b. The reflection portion
114 may be formed to reflect light at a plurality of distances
different from one another based on an area of the reflective
portion 114 that reflects the light, as discussed in greater detail
below. It is possible that paper guides 110a and 110b move with
respect to the center axis (A) according to a moved at least one
paper guide 110a and 110b. It is also possible that one of the
paper guides 110a and 110b moves with respect to the other paper
guide 110a and 110b. In this case, one of the paper guides 110a and
110b is stationary or fixed with respect to the tray, and the other
paper guide 110a 110b is moveable.
[0041] In at least one exemplary embodiment, the light reflector
112 has a stepped configuration. With this configuration, when the
user adjusts the distance between the paper guides 110a and 110b,
it may be possible to change the quantity of light to be reflected
according to the adjusted distance.
[0042] For example, as illustrated in FIG. 2, the reflection
portion 114 may have a stepped configuration including a series of
steps 116 extending from one end of the light reflector 112 to the
opposite end. The width of the steps 116 forming a stairway may
increase in an outward direction toward the sensor as the steps 116
extend from one end of the light reflection 112 to the opposite
end. That is, each step 116 of the light reflector 112 may include
a reflective surface located a predetermined distance away from the
sensor 150. Further, the distance between the sensor 150 and each
step 116 may be different from one another such that a reflective
distance between the sensor 150 and the reflector 112 is different
based on the particular step 116 that reflects the light. For
example, the widths of each step 116 of the light reflector 112 may
increase in a step-wise manner from one end of the light reflector
112 to the opposite end. Accordingly, the reflection distance
between the sensor 150 and the light reflector 112 increases and/or
decreases as the light reflector 112 moves latterly with respect to
the sensor 150. The light reflector 112 may also be realized in
various other configurations to change the quantity of light to be
reflected, including a reverse stepped configuration in which steps
116 forming a stairway become higher inward, or an oblique stepped
configuration in which slopes are interposed between neighboring
steps 116 of the stairway. Hereinafter, the light reflector 112
having the stepped configuration as illustrated in FIG. 2 will be
described.
[0043] The sensor 150 or 250 includes a light emitting element 152
or 252 and a light receiving element 154 or 254. When the light
emitting element 152 or 252 emits a predetermined quantity of light
upon receiving power from a power source, the light is reflected by
the light reflector 112 or 212. The light receiving element 154 or
254 senses the reflected light and outputs a voltage signal
corresponding to the quantity of reflected light. Referring to FIG.
5, it will be appreciated that the greater the distance between the
sensor 150 and the light reflector 112, the smaller the magnitude
of a sensing voltage output from the light receiving element 154 or
254 to a controller 420.
[0044] The following Table 1 represents a relationship between a
paper width (half the actual width), a sensing width, a distance
between the sensor 150 and the light reflector 112, and a sensing
voltage.
TABLE-US-00001 TABLE 1 Distance (x) between Sensor Half Actual
Sensing and Light Sensing Paper Size Width (mm) Width (mm)
Reflector (mm) Voltage (V) A3 148.5 20(a) 6.2 0.75 B4 128.5 20.5(b)
5.9 0.90 Letter/Legal 108 3(c) 5.6 1.13 A4 105 14(d) 5.3 1.33 B5 91
17(e) 5.0 1.59
[0045] Referring to FIG. 4 and Table 1, the light reflector 112 has
a stepped configuration having five steps 116 to sense paper of A3,
B4, A4, letter and B5 sizes. When the light emitted from the light
emitting element 152 or 252 of the sensor 150 or 250 is reflected
by the light reflector 112 or 212 and is introduced into the light
receiving element 154 or 254, the light receiving element 154 or
254 outputs different sensing voltages since the quantity of
reflected light is changed according to the distance (x) between
the sensor 150 and the light reflector 112.
[0046] For example, when A3 size paper is placed on the first paper
tray 120 and the distance between the paper guides 110a and 110b is
adjusted to correspond to the A3 size paper, the light emitted from
the light emitting element 152 of the sensor 150 is reflected by
the light reflector 112 that is spaced apart from the sensor 150 by
the distance x of 6.2 mm and is introduced into the light receiving
element 154 of the sensor 150. In this case, the sensing voltage of
the light receiving element 154 is about 0.75V.
[0047] Referring now to FIG. 4 and Table 1, a sensing width may be
determined based on a difference in a half width of paper. The
half-width of a particular paper size may be determined based on a
predetermined measurement of a half-width of a particular sheet of
paper. For example, considering two sheets of paper having
successive paper sizes, i.e. A3 and B4 sizes, since half a width of
A3 size paper is 148.5 mm and half the width of B4 size paper is
128.5 mm, half the width difference between the A3 size paper and
the B4 size paper is 20 mm. Accordingly, the sensing width (a) of
the A3 size paper is 20 mm. Alternatively, a half-width of a loaded
paper may be calculated based on a difference between a position of
at least one of the first and second paper guides 110a/110b and the
center axis (A) of the paper tray 120.
[0048] Although FIG. 4 illustrates the sensor 150 or 250 in which
the light emitting element 152 or 252 and the light receiving
element 154 or 254 are integrated, a separate light emitting
element (e.g., a light emitting diode) and a separate light
receiving element (e.g., a photo-diode sensor) may be provided.
[0049] Referring now to alternative exemplary embodiment
illustrated in FIG. 3, the second paper tray 220 includes the pair
of paper guides 210a and 210b, first and second racks 211a and 211b
and a pinion 215 to link the paper guides 210a and 210b to each
other, a stepped light reflector 212, and the sensor 250 to emit
light to the light reflector 212 so as to measure the quantity of
light reflected by the light reflector 212. Although the second
paper tray 220 takes the form of a drawer type paper cassette, the
same conceptual embodiment as the light reflector 112 and the
sensor 150 illustrated in FIG. 2, and discussed in detail above may
be applied to the second paper tray 220. The pair of paper guides
211a and 211b are arranged to guide both lateral ends of paper.
[0050] FIG. 6 is a control block diagram of the image forming
apparatus according to an embodiment.
[0051] As illustrated in FIG. 6, the image forming apparatus
includes an input unit 400, a memory 410, the controller 420, a
drive unit 430 and the sensors 150 and 250. The input unit 400
includes a display window to show operational and error status of
the image forming apparatus and a keypad to allow the user to
select a variety of printing modes. The memory 410 consists of a
Read Only Memory (ROM) in which a variety of control programs
required to realize functions of the image forming apparatus are
stored, and a Random Access Memory (RAM) in which a variety of
programs generated according to implementation of the control
programs are stored. The controller 420 controls general operations
of the image forming apparatus. The drive unit 430 realizes an
image forming apparatus mechanism to perform a printing operation
under control of the controller 420. The sensors 150 and 250 to
sense the size of paper loaded in the image forming apparatus
respectively include the light emitting elements 152 and 252 to
emit light, and the light receiving elements 154 and 254 to receive
the light reflected by the light reflectors 112 and 212 so as to
output voltage signals corresponding to the quantity of reflected
light.
[0052] The memory 410 stores the sensing voltages of the light
receiving elements 154 and 254 according to distances between the
light reflector 112 and the sensor 150 and between the light
reflector 212 and the sensor 250. The memory 410 also stores paper
size data corresponding to the sensing voltages. For example,
according to the data stored in the memory 410, a paper size
corresponding to the sensing voltage of 0.75V is an A3 size (see
Table 1). Also, the memory 410 stores an error range of the sensing
voltage. Accordingly, if the sensing voltage slightly differs from
the stored value, but falls within the error range, it may be
determined that the sensing voltage designates a corresponding
paper size.
[0053] The controller 420 confirms whether or not paper is newly
loaded in the paper trays 120 and 220. If loading of new paper is
confirmed, the controller 420 controls the light emitting elements
152 and 252 to emit light to the light reflectors 112 and 212.
[0054] The image forming apparatus may also include a paper
detecting sensor and a paper cassette entrance/exit detecting
sensor, to confirm whether or not paper is newly loaded on the
first paper tray 120 or the second paper tray 220. The paper
detecting sensor (not shown) is installed to the body 100 of the
image forming apparatus so as to be located at an upper lateral
side of the first paper tray 120. If the sensor emits light to
paper and senses the light reflected by the paper, the presence of
paper is determined. On the other hand, if the sensor fails to
receive light emitted therefrom (because the emitted light passes a
hole (not shown) formed in the first paper tray 120 in which no
paper is loaded, the absence of paper is determined. The controller
420 determines loading of new paper if paper is not initially
detected from the first paper tray 120, but is detected later. The
paper cassette detecting sensor (not shown) is provided in the body
100 of the image forming apparatus to interfere with the second
paper tray 220. The paper cassette detecting sensor may be a
contact type or non-contact type sensor to interfere with the
second paper tray 220 and is adapted to sense
separation/reinstallation of the second paper tray 220. If
separation/reinstallation of the second paper tray 220 is confirmed
based on a signal transmitted from the paper cassette detecting
sensor, the controller 420 determines that paper is newly loaded
into the second paper tray 220. The paper detecting sensor and the
paper cassette detecting sensor are known technologies and thus,
detailed descriptions thereof will be omitted herein.
[0055] The light emitted from the light emitting element 152 or 252
is reflected by the light reflector 112 or 212 that has been moved
in linkage with the paper guides 110a and 110b or 210a and 210b as
the user adjusts the distance between the paper guides according to
a paper width. The light reflected by the light reflector 112 or
212 is introduced into the light receiving element 154 or 254 of
the sensor 150 or 250 and in turn, the light receiving element 154
or 254 outputs the sensing voltage, corresponding to the quantity
of received light, to the controller 420. The controller 420 reads
paper size information corresponding to the sensing voltage from
the memory 410, thereby confirming a paper size. For example, if
the sensing voltage of 0.9V is input from the light receiving
element 154 or 254 to the controller 420, the controller 420
confirms that the paper loaded into the paper tray 120 or 220 is B4
size paper (see Table 1). Also, if the sensing voltage of 0.28V is
input from the light receiving element 154 or 254 to the controller
420, the controller 420 confirms that the paper loaded into the
paper tray 120 or 220 is A5 size paper. Here, it is noted that the
controller 420 may confirm a paper size corresponding to the
sensing voltage even if the sensing voltage slightly differs from a
value stored in the memory 410, but falls within a preset error
range.
[0056] FIG. 7 is a control flow chart of the image forming
apparatus according to an exemplary embodiment of the general
inventive concept.
[0057] As illustrated in FIG. 7, the controller 420 confirms
whether or not paper is loaded into the paper tray 120 or 220. If
the paper detecting sensor (not shown) initially fails to sense the
presence of paper inside the first paper tray 120, but senses paper
later, the controller 420 determines that paper is newly loaded
into the first paper tray 120. Also, if it is confirmed according
to a signal transmitted from the paper cassette detecting sensor
(not shown) that the second paper tray 220 is separated from the
body 100 and thereafter, is reinstalled into the body 100, the
controller 420 determines that paper is newly loaded into the
second paper tray 220 (500).
[0058] Next, after confirming loading of new paper into the paper
trays 120 and 220, the controller 420 controls the sensors 150 and
250 so that the sensors 150 and 250 emit light and receive the
light reflected by the light reflectors 112 and 212. The light
reflectors 112 and 212 are moved respectively in linkage with the
paper guides 110a and 110b and the paper guides 210a and 210b, and
have any one of various stepped configurations, including forward
and reverse stepped configurations, to change the quantity of light
to be reflected according to the adjusted distances between the
paper guides 110a and 110b and between the paper guides 210a and
210b (510).
[0059] Next, the sensors 150 and 250 output sensing voltages,
corresponding to the quantity of light reflected by the light
reflectors 112 and 212, to the controller 420. The smaller the
distance between the sensor 150 and the light reflector 112 or
between the sensor 250 and the light reflector 212, the greater the
quantity of light introduced into the sensor 150 or 250. In turn,
the greater the quantity of light introduced into the sensor 150 or
250, the greater the sensing voltage. The sensors 150 and 250
respectively include the light emitting elements 152 and 252 and
the light receiving elements 154 and 254, which may be integrally
formed with each other or may be separated from each other
(520).
[0060] Next, the controller 420 determines the size of paper loaded
into the paper trays 120 and 220 according to the sensing voltages
output from the sensors 150 and 250. The sensing voltages and
corresponding paper sizes are previously stored in the memory 410.
The controller 420 may determine a paper size corresponding to the
sensing voltage if the sensing voltage is equal to a value stored
in the memory 410 or falls within an error range of the value
(530).
[0061] Next, the controller 420 stores the determined paper size in
the memory 410 and controls driving of the image forming apparatus
according to the stored paper size information during a printing
operation (540).
[0062] As apparent from the above description, according to an
embodiment of the present general inventive concept, a paper
feeding device includes a light reflector having a stepped
reflection surface corresponding to various paper widths.
Accordingly, the size of paper may be recognized using a single
sensor and the light reflector without requiring a plurality of
sensors, resulting in reduction in cost and volume.
[0063] Although a few embodiments of the present general inventive
concept have been shown and described, it would be appreciated by
those skilled in the art that changes may be made in these
embodiments without departing from the principles and spirit of the
general inventive concept, the scope of which is defined in the
claims and their equivalents.
* * * * *