U.S. patent application number 11/452951 was filed with the patent office on 2007-01-04 for image forming apparatus.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. Invention is credited to Takashi Yano.
Application Number | 20070001366 11/452951 |
Document ID | / |
Family ID | 37588496 |
Filed Date | 2007-01-04 |
United States Patent
Application |
20070001366 |
Kind Code |
A1 |
Yano; Takashi |
January 4, 2007 |
Image forming apparatus
Abstract
An image forming apparatus of the present invention intends to
reduce a difference of usage frequency among a plurality of sheet
feeding section and comprises: a plurality of sheet feeding section
capable of feeding different types of sheets; a printer main body
for forming an image on a sheet fed by the sheet feeding section;
an accumulation counter for counting the accumulation quantity of
fed sheets of each of the plural sheet feeding section; and a
controller for determining bias of usage frequency of each sheet
feeding section based on a counting result of the accumulation
counter and changing the allocation of the sheets of each sheet
feeding section to reduce the bias of the usage frequency of each
sheet feeding section.
Inventors: |
Yano; Takashi;
(Shizuoka-Ken, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
CANON KABUSHIKI KAISHA
TOKYO
JP
|
Family ID: |
37588496 |
Appl. No.: |
11/452951 |
Filed: |
June 15, 2006 |
Current U.S.
Class: |
271/9.01 |
Current CPC
Class: |
B65H 2511/30 20130101;
B65H 2601/423 20130101; B65H 2513/42 20130101; B65H 2220/02
20130101; B65H 2220/01 20130101; B65H 3/44 20130101; B65H 2511/30
20130101; B65H 2513/42 20130101; B65H 2601/522 20130101 |
Class at
Publication: |
271/009.01 |
International
Class: |
B65H 3/44 20060101
B65H003/44 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2005 |
JP |
2005-191408 |
Claims
1. An image forming apparatus comprising: a plurality of sheet
feeding sections capable of feeding different types of sheets; an
image forming portion which forms an image on a sheet fed by the
sheet feeding sections; an accumulation feeding quantity counting
means capable of counting the accumulation quantity of fed sheets
of each of the plural sheet feeding sections; and a control means
which determines the bias of usage frequency of each sheet feeding
sections based on a counting result of the accumulation feeding
quantity counting means and changes the allocation of the sheets of
each sheet feeding sections so as to reduce the bias of the usage
frequency of each sheet feeding sections.
2. The image forming apparatus according to claim 1, wherein the
control means, when a difference between accumulation quantity of
fed sheets of any two sheet feeding sections of the plural sheet
feeding sections is larger than a predetermined value, changes the
allocation of the sheet based on a count result of the accumulation
feeding quantity counting means and when the difference of the
accumulation quantity of the fed sheets is smaller than the
predetermined value, does not change the allocation of the
sheet.
3. The image forming apparatus according to claim 2, wherein an
alarm signal is outputted when the allocation of the sheets by the
control means is necessary.
4. The image forming apparatus according to claim 1 further
comprising: a usage frequency calculating means for calculating the
usage frequency of each of the plural sheet feeding sections in a
predetermined period up to currently, wherein when a difference
between accumulated quantities of fed sheets of any two sheet
feeding sections of the plural sheet feeding sections is over a
predetermined value and the usage frequency of a sheet feeding
section, whose accumulation quantity of fed sheets is smaller of
the two sheet feeding section, is lower than the usage frequency of
the other sheet feeding section, whose accumulation quantity of fed
sheets is larger of the two sheet feeding sections, based on a
counting result of the accumulation feeding quantity counting means
and a calculation result of the usage frequency calculating means,
the control means changes the allocation of the sheets.
5. The image forming apparatus according to claim 4, wherein an
alarm signal is outputted when the allocation of sheets by the
control means is necessary.
6. The image forming apparatus according to claim 1, further
comprising a notifying means for notifying the allocation of sheets
changed by the control means.
7. The image forming apparatus according to claim 6, wherein the
notifying means is capable of transmitting a result of sheet
allocation to an external device through communication means.
8. The image forming apparatus according to claim 1, wherein when
the types of sheets set in the sheet feeding sections are equal in
two or more sheet feeding sections, sheets are allocated to use the
sheet feeding sections whose accumulation quantity of fed sheets is
smaller with preference.
9. The image forming apparatus according to claim 1, wherein
determination of bias of the usage frequency of each sheet feeding
sections by the control means is started in each predetermined
period.
10. The image forming apparatus according to claim 1, wherein the
determination of bias of the usage frequency of each sheet feeding
sections by the control means is started in each predetermined
period after the power of the apparatus main body is turned on.
11. The image forming apparatus according to claim 1, wherein the
determination of bias of the usage frequency of each sheet feeding
sections by the estimation means is started each time when the
accumulation quantity of fed sheets to the apparatus main body
reaches a predetermined one.
12. The image forming apparatus according to claim 1, wherein the
determination of bias of the usage frequency of each sheet feeding
sections by the estimating means is started according to an
instruction from outside through a receiving means.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an image forming apparatus
having a plurality of sheet feeding sections.
[0003] 2. Description of the Related Art
[0004] Generally, the image forming apparatus such as a copier and
printer is provided with a plurality of feeding trays. Different
kinds of sheets are often set in these feeding trays depending on
user's usage purpose. In the meantime, the "different kinds" means
that at least one of various parameters for specifying the sheet,
such as its material, thickness, size is different.
[0005] When a print job is received, the controller of the image
forming apparatus selects a feeding tray in which sheets of
material and thickness specified by user are accommodated or a
feeding tray in which sheets of a size suitable for the size of
image to be formed are accommodated and starts image forming
operation.
[0006] Generally, when different kinds of sheets are set in a
plurality of the feeding trays, a difference in frequency of usage
occurs depending on sheets used usually or sheets used rarely. In
an ordinary office environment, the usage frequency of plain paper
or thick paper of A3 size or B4 size is low although its demand
exists while the plain paper of A4 size or B5 size is used
frequently. when the difference of the usage frequency is
accumulated, a large bias is generated in the accumulation
quantities of fed sheets among the feeding trays.
[0007] An ordinary feeding apparatus conveys and separates the
sheets using a rubber roller or rubber pad. These members are worn
and deteriorated as the quantity of sheets increases and their
surfaces are deteriorated when they are left in an unused state for
a long time. when this deterioration progresses, the friction
coefficient of a contact face with the sheet drops or the
conveyance amount drops due to wearing of the outer periphery of
the roller, so that a jam due to a conveyance delay or double
feeding occurs. This state is called fulfilled service life of the
feeding roller or separating pad.
[0008] When there exists a bias in the usage frequency among the
feeding trays as described above, rollers of the feeding trays used
frequently are worn unevenly or the rollers of the feeding tray
used less frequently are deteriorated because they are left not
used, so that the service life is fulfilled early. As a
consequence, such a trouble as jamming and double feeding is likely
to occur. Further, there occurs such a problem that a service
person needs to replace the feeding rollers frequently. To
eliminate these problems, the usage frequency of the feeding tray
needs to be equalized.
[0009] Then, the method described in Japanese Patent Application
Laid-Open No. 2002-255380 has been proposed conventionally as case
where sheets of the same size and same kind are set in a plurality
of feeding trays.
[0010] That is, this feeding portion including a plurality of sheet
storage portions for accommodating sheets of the same size and
material is provided with a selecting means for selecting a sheet
storage portion from which sheets are to be fed, in order to
equalize the accumulation feeding frequency of each sheet storage
portion.
[0011] However, the above-described conventional technology is
premised on that sheets of the same size and kind are set in the
plurality of the feeding trays. Thus, that conventional technology
cannot be applied to an ordinary use condition in which sheets of
different kinds are set in each feeding tray.
SUMMARY OF THE INVENTION
[0012] Accordingly, an object of the present invention is to
provide an image forming apparatus capable of reducing a difference
in the usage frequency among the plurality of the sheet feeding
sections.
[0013] To achieve above-mentioned object, the present invention
provides an image forming apparatus comprising:
[0014] a plurality of sheet feeding sections capable of feeding
different types of sheets;
[0015] an image forming portion which forms an image on a sheet fed
by the sheet feeding sections;
[0016] an accumulation feeding quantity counting means for counting
the accumulation quantity of fed sheets of each of the plural sheet
feeding sections; and
[0017] a control means which determines the bias of usage frequency
of each sheet feeding sections based on a counting result of the
accumulation feeding quantity counting means and changes the
allocation of the sheets of each sheet feeding sections to reduce
the bias of the usage frequency of each sheet feeding sections.
[0018] The present invention can reduce the difference in the usage
frequency among the plurality of the sheet feeding sections.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The invention, together with further advantages thereof, may
best be understood by reference to the following description taken
in conjunction with the accompanying drawings in which:
[0020] FIG. 1 is a flow chart showing an example of frequency
equalizing processing of the embodiment of the present
invention;
[0021] FIG. 2 is a diagram showing an example of the profile of
each feeding tray of the present invention;
[0022] FIG. 3 is a diagram showing an example of the profile after
the kinds of sheets used in each feeding tray of the invention are
reallocated;
[0023] FIG. 4 is a diagram showing an example of the profile of
each feeding tray of the invention;
[0024] FIG. 5 is a diagram showing an example of the profile after
the kinds of sheets used in each feeding tray of the invention are
reallocated;
[0025] FIG. 6 is a schematic sectional view of an image forming
apparatus of the embodiment of the present invention; and
[0026] FIG. 7 is a block diagram of a control portion of the
embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] Hereinafter, the best mode for carrying out the present
invention will be described in detail with reference to the
accompanying drawings and embodiments. However, the dimension,
material, shape, relative arrangement and the like of components
described in the embodiments do not restrict the invention to only
those unless specified otherwise. The material, shape and the like
of members described in a following description are the same as in
description of background art unless specified otherwise.
[0028] (Image Forming Apparatus)
[0029] An example of the image forming apparatus which can adopt
the present invention preferably will be described with reference
to FIG. 6. FIG. 6 shows the image forming apparatus according to an
embodiment of the present invention.
[0030] An image forming apparatus 100 comprises a printer main body
1 for forming an image on a sheet and a reading portion 2 for a
case where it is made to function as a copier. Although this
embodiment will be described about a copier type image forming
apparatus having the reading portion, the present invention may be
applied to a printer type image forming apparatus having no reading
portion.
[0031] A laser scanner 11 for writing an image to a photosensitive
drum 12 is provided on the top of the printer main body 1. Print
data sent from an external apparatus such as a personal computer is
received by a controller 40 which controls the printer main body 1
and outputted to a laser scanner 11 as written image data.
[0032] A plurality of sheet feeding sections 30a, 30b, 30c, 30d
capable of feeding different kinds of sheets are located in the
uppermost stream of sheet conveyance. In the image forming
apparatus 100 of this embodiment, the sheet feeding sections 30a to
30d are provided in line vertically in the bottom portion of the
apparatus. The sheet feeding sections 30a, 30b, 30c, 30d include
feeding trays A, B, C, D for stacking and storing the sheets S and
feeding portions 31a, 31b, 31c, 31d which separate the sheets S
stored in the feeding tray and feed them.
[0033] The feeding portion 31a (because the feeding portions 31b,
31c, 31d have substantially the same structure as the feeding
portion 31a, description of those is omitted) includes a pickup
roller 50 for picking up a sheet S in the feeding tray A, a feeding
roller 51 for feeding the sheet S picked up by the pickup roller 50
and a separation roller 52 which opposes the feeding roller 51 for
separating the sheets S by giving a separation force in a return
direction to the sheet.
[0034] A conveyance roller pair 36a (36b, 36c, 36d) which takes
over the sheet S fed by the feeding roller 51 and after conveyance
by the feeding roller 51 ends, pulls out the sheet from nipping
between the feeding roller 51 and the separation roller 52 are
provided in the downstream of the feeding roller 51.
[0035] The conveyance roller pair 36a has a role of taking over the
sheet S conveyed through a longitudinal conveyance path 35 from a
feeding section (for example, sheet feeding section 30d) located
further in the upstream in addition to this pulling action.
[0036] FIG. 7 is a block diagram of the control portion according
to an embodiment. As shown in FIG. 7, an accumulation counter 40a
for measuring the quantity of fed sheets is incorporated in the
controller 40. The accumulation counter 40a counts the quantity of
fed sheets from each feeding tray in cooperation with a feeding
action signal and its count value is stored in a memory 40b.
[0037] A resist roller pair 81 is provided at the lowermost stream
position of the longitudinal conveyance path 35. This resist roller
pair 81 executes the final skew correction of the sheet and
matching of timing between image writing and sheet conveyance in
the image forming portion.
[0038] The printer main body 1 includes a photosensitive drum 12,
charger 13, laser scanner 11, development portion 14, transfer
roller 19 and cleaner 26. The charger 13 charges the surface of the
photosensitive drum 12 equally. The laser scanner 11 forms an
electrostatic latent image by irradiating light to the surface of
the photosensitive drum 12 charged by the charger 13. The
development portion 14 develops the electrostatic latent image as a
toner image with developing agent. The transfer roller 19 transfers
a developed toner image to the sheet S. The cleaner 26 removes
toner left in the photosensitive drum 12 after the toner image is
transferred.
[0039] A conveying portion 21 for conveying the sheet S after the
toner image is transferred and a fixing portion 22 for fixing an
image on the sheet S conveyed by this conveying portion 21 as a
permanent image are provided in the downstream of the image forming
portion.
[0040] A discharge roller 24 for discharging the sheet S after the
image is fixed by the fixing portion 22 from the printer main body
1 is provided. A discharged sheet stacking tray 25 which receives
sheets S discharged by the discharge roller 24 is provided outside
the top portion of the printer main body 1.
[0041] (Usage Frequency Equalizing Method)
[0042] Next, a method of equalizing the usage frequency as much as
possible by reducing a difference of the usage frequency among the
plurality of the sheet feeding sections of this embodiment will be
described.
[0043] The pickup roller 50, the feeding roller 51 and the
separation roller 52 equipped on the feeding portion 31 included in
the sheet feeding section are worn (wasted) gradually with feeding
of the sheets as described above. The wearing of the feeding roller
51 and the separation roller 52 is large because the load upon
feeding is large and they need to be replaced several times until
the service life of the image forming apparatus is fulfilled.
[0044] When any particular feeding portion of the plurality of the
feeding portions is used unevenly at a high frequency, only the
roller of that feeding portion is deteriorated early so that the
service life for replacement is reached early and the replacement
timings of the plural feeding portions become uneven. As a result,
the number of maintenance for replacement of the roller increases
or troubles such as jam or double feeding may occur because partial
feeding portions are operated in a condition requiring maintenance
in a long period.
[0045] Thus, in the image forming apparatus of the present
invention, the controller 40 is provided with a function for
equalizing the usage frequency of each feeding tray as much as
possible.
[0046] As described above, the controller 40 is provided with the
accumulation counter 40a for counting the quantity of sheets fed
from each feeding tray and the accumulation quantity of the sheets
fed from each feeding tray is measured and the measured value is
stored in the memory 40b of the controller 40. Further, the
controller 40 is also provided with a reservation counter 40c for
calculating a recent usage frequency of each sheet feeding sections
in a predetermined period up to currently. This reservation counter
40c measures the quantity of sheets fed in a specified period back
with respect to currently and its value is always recorded in the
memory 40b of the controller 40. That is, this value is used as a
recent usage frequency of the sheets set in each feeding tray.
[0047] In how long a period the usage frequency is to be measured
with respect to currently may be changed depending on the apparatus
usage condition of user and according to this embodiment, this
period is set to a week by presuming the use condition of ordinary
office.
[0048] As other function, the controller 40 has a bias detecting
function for determining whether or not the use condition of each
feeding tray is biased and a frequency equalizing function which
when it is determined that the use condition is biased, estimates a
sheet allocation to each feeding tray which can relax the bias.
[0049] Next, the above-described equalizing processing will be
described specifically below. FIG. 1 shows a schematic flow chart
of this frequency equalizing processing. In the meantime, the
processing below can be executed in viewpoints of both hardware and
software by the controller 40 as an estimating means in which a
well known arithmetic operating means (CPU) 40d and memory means
(memory) 40b are combined.
[0050] When the bias detecting processing is started by a timer in
each predetermined period in step S1 as shown in FIG. 1, the
controller 40 refers to the value of the accumulation quantity of
fed sheets by each sheet feeding sections measured by the
accumulation counter 40a.
[0051] Next, the procedure proceeds to step S2, in which a
difference DIF between a value Cmax of a sheet feeding section
whose accumulation quantity of fed sheets is maximum and a value
Cmin of a sheet feeding section whose accumulation quantity of fed
sheets is minimum is compared with a set threshold TH. In the
meantime, according to this embodiment, the threshold TH is set to
30,000.
[0052] Unless the difference DIF exceeds the threshold TH (No in
S2), it is determined that the usage frequency of each sheet
feeding sections is not so biased and then, the bias detecting
processing is ended.
[0053] On the other hand, when the difference DIF is over the
threshold TH (Yes in S2), the procedure proceeds to step S3, in
which the values measured by the reservation counter 40c are
referred to about those two feeding trays. After that, the
procedure proceeds to step S4, in which a recent usage frequency is
compared.
[0054] When the recent usage frequency F1 of the sheet feeding
section whose accumulation quantity of fed sheets is minimum is
lower than the recent usage frequency F2 of the sheet feeding
section whose accumulation quantity of fed sheets is maximum (Yes),
the procedure proceeds to step S5. Then, it is determined that the
bias of the usage frequency of the both feeding trays may not be
improved in future and an alarm signal is outputted in step S5.
when the usage frequencies of the both are in an opposite relation
(No), the difference of the accumulation quantity of fed sheets can
be relaxed by a future print operation, so that no alarm signal is
outputted and then, the processing is ended.
[0055] In the present invention, the usage frequency means the
frequency at which the sheet feeding section feeds the sheet. For
example, the usage frequency can be expressed as the quantity of
sheets fed per a portion time. The degree of wearing of the feeding
roller, separation pad and the like can be estimated with such a
usage frequency to some extent.
[0056] The frequency equalizing processing is triggered when the
alarm signal is outputted in the bias detecting processing (step
S6).
[0057] In a processing of this embodiment, the controller 40
introduces a sheet type preferred to be used in each feeding tray
according to the accumulation quantity of fed sheets C by each
sheet feeding sections measured by the accumulation counter 40a and
the recent usage frequency F of each sheet feeding sections (or
type of sheet set in each feeding tray) measured by the reservation
counter. when there exist a plurality of feeding trays for feeding
the same kind of sheets, the controller 40 finds out which feeding
tray should be used with preference.
[0058] The types of sheets to be used in each feeding tray are
allocated to the feeding trays whose accumulation quantity of fed
sheets is small with preference in order from sheet of material and
size having the highest usage frequency currently. As a
consequence, allocation of the type of the sheet recommended to be
used in each feeding tray is determined so that the difference in
usage frequency among the plurality of the sheet feeding sections
can be reduced by a following sheet feeding operation.
[0059] Next, a specific processing flow will be described assuming
a condition in which these functions operate actually. The image
forming apparatus of this embodiment can execute a scheduled
operation using a timer and thus, bias check of the usage condition
of each sheet feeding sections by the bias detecting processing is
automatically executed at a predetermined time once a week.
[0060] The controller 40 outputs an instruction for the bias
detecting processing of determining whether or not there exists a
bias in the usage frequency of each feeding tray. Assume that when
this instruction is dispatched, the profile of each feeding tray is
as shown in FIG. 2. At this time, the difference DIF between the
value Cmax (43057) of a feeding tray A whose accumulation quantity
of fed sheets is maximum and the value Cmin (12502) of a feeding
tray D whose accumulation quantity of fed sheets is minimum is
30555. As described above, because the threshold TH for the bias
determination is set to 30000 according to this embodiment, this
difference DIF is over the threshold TH.
[0061] Because as a result of comparing the recent usage
frequencies of sheets set in the both feeding trays, the feeding
tray A (F2=1509/week) is used more frequently than the feeding tray
D (F1=109/week), the alarm signal is outputted (step S5).
[0062] When the alarm signal is outputted, the frequency equalizing
processing is started (step S6). The result of an ideal allocation
of the sheet type in each feeding tray obtained in the
above-described processing is outputted to eliminate the bias of
the usage frequency in a future image forming operation (step
S7).
[0063] The profile after the reallocation of the sheet types used
in each feeding tray is as shown in FIG. 3 according to this
embodiment. This output result is displayed on a display portion as
a notifying means for notifying user of the sheet allocation. In
the meantime, the notifying means of this embodiment may adopt a
structure four notifying user with voice or blinking of a light
emission device as well as the display portion such as the display
portion described later.
[0064] A message recommending to change the allocation condition of
the sheet types in each feeding tray to the profile shown in FIG. 3
is displayed on the display portion 3 of the image forming
apparatus 100 (step S8). A thick paper A3 whose accumulation
quantity of fed sheets is the smallest is set in the feeding tray A
whose accumulation quantity of the fed sheets is the largest and a
plain paper A3 whose accumulation quantity of the fed sheets is
next to the smallest is set in the feeding tray C whose quantity of
the fed sheets is next to the largest.
[0065] Although the feeding tray B has a next largest quantity, the
plain paper A4 whose accumulation quantity of the fed sheets is the
largest is set in the feeding tray B having a low usage frequency
currently because the feeding tray D has a higher usage frequency
currently. In this manner, user changes the allocation of the
sheets to the feeding trays according to such an instruction. That
is, as shown in FIG. 3, the feeding trays are replaced so that the
sheets of the types allocated to each feeding tray are stored
therein (step S9). As a result, the difference in the quantity of
the accumulation quantity of the fed sheets among the sheet feeding
sections is eliminated gradually through a following print
operation.
[0066] As already described in this embodiment, the bias of the
accumulation quantity of fed sheets among the respective sheet
feeding sections can be suppressed to a specific range by checking
periodically with the bias detecting processing, so that the
difference in the usage frequency among the plural sheet feeding
sections can be reduced.
[0067] Next, processing of this embodiment in case where the sheet
materials of the same kind and size are set in a plurality of the
feeding trays will be described. In the image forming apparatus of
this embodiment, a preference order for use is allocated to the
plurality of the feeding trays in which the same sheets are set and
when there are left sheets in a feeding tray having a higher
preference order, they are fed first of all necessarily.
[0068] Assume that when an instruction for the bias detecting
processing is dispatched, the profile of the respective feeding
trays is as shown in FIG. 4. At this time, a difference between the
value Cmax (44160) of the feeding tray A whose accumulation
quantity of fed sheets is maximum and the value Cmin (13022) of the
feeding tray C whose accumulation quantity of fed sheets is minimum
is 31138. Because the bias determination threshold TH of this
embodiment is set to 30000, it comes that the value of this
difference DIF is over the threshold TH.
[0069] Because the feeding tray A (F2=1612/week) is used more
frequently than the feeding tray C (F1=109/week) when the recent
usage frequencies of sheets set in both the feeding trays are
compared, an alarm signal is outputted in step S5.
[0070] When the alarm signal is outputted, the procedure proceeds
to step S6, in which the frequency equalizing processing is
started. An estimation result of the ideal allocation of the sheet
type used in each feeding tray obtained in the previously described
processing is outputted to eliminate the bias of the usage
frequency in the image forming operation in the future naturally
(S7). In this case, the profile after the types of the sheets used
in each feeding tray are reallocated is as shown in FIG. 5. At this
time, a higher selection preference order is automatically
allocated to two feeding trays in which the plain papers of A4 size
of the same kind are set in the order from a feeding tray to which
the sheets are reallocated whose accumulation quantity of fed
sheets is smaller.
[0071] A message which recommends user to change the allocation
condition of sheets to each feeding tray to this profile is
displayed on the display portion 3 of the image forming apparatus
100 (step S8). The procedure proceeds to step S9, in which user
inputs a setting change to the display portion 3 and then, the
procedure proceeds to step S10, in which the types of the sheets to
be set in each feeding tray are replaced by the user actually. As a
consequence, the controller 40 recognizes the sheets of the types
indicated on the display portion through a detecting means for
detecting that they are loaded on the respective sheet feeding
sections and this preference order is applied. Consequently, an
error of replacement of the plural sheet types can be reduced by
provision of such a detecting means. Then, the procedure proceeds
to step S11, in which the values of the reservation counter are
replaced corresponding to the feeding trays which replace the sheet
types.
[0072] In the meantime, the present invention is not restricted to
the above-described embodiments. Although this embodiment adopts a
structure of executing the bias detecting processing periodically
by schedule control, this bias detecting processing may be executed
necessarily within a predetermined time after the apparatus main
body is powered on.
[0073] In addition, difference in accumulation quantity of fed
sheets is always counted for each print job, then the
above-described processing may be executed when the difference
exceeds the threshold.
[0074] The above-described processing may be executed each time
when the accumulation quantity of fed sheets to the apparatus main
body reaches a predetermined number instead of the accumulation
quantity of the fed sheets by the sheet feeding section. For
example, that processing may be executed each time when the
accumulation quantity of the fed sheets to the apparatus main body
reaches 100,000.
[0075] Information of each sheet feeding sections for which the
sheet allocation is changed may be transmitted to outside through
communication means. Such a structure enables the usage frequency
of each sheet feeding sections to be notified to an outside service
center or the like, thereby making it possible to estimate a
replacement timing of the roller or separation pad to lead to
effective maintenance.
[0076] The trigger of the bias detecting processing may be executed
according to an instruction from outside by user or according to an
instruction through remote control from an outside service station
connected through communication line. With such a structure, the
usage frequency of a sheet feeding sections having a high usage
frequency can be reduced according to an instruction from outside
even when the feeding components of part of the sheet feeding
section are worn so that jam is likely to occur. Therefore,
conveyance trouble before maintenance can be reduced.
[0077] In this embodiment, the reallocation processing of
equalizing the degree of wearing of members used in each feeding
tray is carried out by rearrangement of the feeding trays using
comparison of difference of the accumulation quantity of fed sheets
by the accumulation counter and the recent usage frequency by the
reservation counter. However, the present invention is not
restricted to this processing algorithm. That is, when higher
arithmetic operating processing can be executed on the controller
side, more effective equalization is possible by recording history
of previous size changes and the trend of the usage frequency of
each sheet type and using such information for processing.
[0078] Because a conveyance distance required for conveying a sheet
varies depending on the sheet size, the above processing may be
carried out corresponding to not only the quantity of sheets but
also an accumulated conveyance distance (=quantity of fed
sheets.times.paper size). As a consequence, the degree of wearing
of the feeding members such as the pickup roller, feeding roller
and separation roller can be more equalized in each sheet feeding
member. Thus, the component replacement timing of each sheet
feeding sections can be aligned thereby achieving effectiveness of
maintenance.
[0079] In the description of this embodiment, it is described that
the sheets in each feeding tray are replaced. However, when the
sheet storage portion of the feeding trays A to D can be removed
from the printer main body 1 and replaced with each other, the
types of the sheets preferred to be fed by each sheet feeding
sections may be replaced by replacing the sheet positions together
with the feeding trays.
[0080] As described above, according to the present invention, the
difference of the usage frequency of the respective sheet feeding
sections can be reduced not only among the plural sheet feeding
sections loaded with the same type of sheets but also among the
plural sheet feeding sections loaded with different type of sheets,
which cannot be achieved conventionally.
[0081] As a consequence, such replaceable members as the feeding
roller and separation roller included in particular sheet feeding
sections can be prevented from being worn unevenly in a short
period or being kept not used in a long period, thereby reducing
the occurrence frequency of trouble such as jamming or double
feeding.
[0082] Further, because all the feeding rollers and separation
rollers can be used in a same pace, maintenance interval for
component replacement by a service person can be expanded to its
maximum extent. Further, because the consumption parts of all the
sheet feeding sections can be replaced in a single maintenance at
the same time, the frequency of visits by the service person can be
reduced largely.
[0083] This application claims priority from Japanese Patent
Application No. 2005-191408 filed Jun. 30, 2005, which is hereby
incorporated by reference, herein.
* * * * *