Electrophotography – Document handling – Copy
Reexamination Certificate
1999-12-29
2001-01-30
Brase, Sandra (Department: 2852)
Electrophotography
Document handling
Copy
C399S388000
Reexamination Certificate
active
06181907
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a paper supply control apparatus in a printer and a paper supply method, and more particularly, to a paper supply control apparatus in a printer capable of controlling the paper supply time in response to variations in the circulation cycle of a photoreceptor belt, and a paper supply method for the same.
2. Description of the Related Art
Referring to
FIG. 1
, a printer includes a printing portion
10
and a paper supplying portion
30
for supplying a sheet of paper to the printing portion
10
.
The printing portion
10
is comprised of a photoreceptor belt
14
, a reset device
15
, optical scanning devices
16
, developers
17
, a drying unit
18
, and a transfer unit
19
.
The reset device
15
includes an exposing device
15
a
for projecting light onto electrostatic latent images remaining on the photoreceptor belt
14
circulated by a plurality of rollers
11
,
12
and
13
to erase the electrostatic latent images, and a charger
15
b
for charging the photoreceptor belt
14
with a predetermined potential to write new electrostatic latent images on the photoreceptor belt
14
.
The optical scanning devices
16
form electrostatic latent images on the photoreceptor belt
14
by scanning light corresponding to image information.
The developers
17
develop electrostatic latent images formed on the photoreceptor belt
14
by the optical scanning device
16
, using developing agents.
The drying unit
18
is used when a developing solution mixed with a toner and a liquid carrier element is used as the developing agent. The drying unit
18
absorbs and evaporates the liquid carrier element, which does not participate in forming images, from the photoreceptor belt
14
.
The transfer unit
19
transfers images formed with toner on the photoreceptor belt
14
to a fed sheet of paper
31
.
The paper supplying portion
30
is comprised of a paper feeding cassette
32
, a pickup roller
33
for picking up sheets of paper
31
placed in the paper feeding cassette
32
, and a plurality of transfer rollers
35
installed along a paper transfer path
34
ranging from the pickup roller
33
to the transfer unit
19
in the printing portion
10
in order to transfer a picked-up sheet of paper
31
.
Reference numeral
40
is a recognition pattern detecting sensor including an optical source
41
and an optical detector
42
. As shown in
FIG. 2
, at a fixed position, the recognition pattern detecting sensor
40
detects passage of a recognition pattern
43
formed at a predetermined position departing from an image writing area D on the photoreceptor belt
14
, and outputs a signal indicating the arrival of the recognition pattern
43
.
Meanwhile, a sheet of paper
31
must be fed to the transfer unit
19
in accordance with the time when toner images formed on the photoreceptor belt
14
are transferred to the transfer unit
19
.
To do this, in the prior art, an engine controller (not shown) sets the time to form images on the photoreceptor belt
14
on the basis of receiving the recognition pattern arrival signal from the recognition pattern detecting sensor
40
, and the time required for paper pickup such that they are matched to an image transfer time. The image transfer time is the time it takes to transfer images formed on the photoreceptor belt
14
to a picked-up sheet of paper
31
. Thus, the engine controller, which controls the printing portion
10
and the paper supplying portion
30
, drives the pickup roller
33
to pick up a sheet of paper
31
at a predetermined paper pickup time after a counted time from receiving the recognition pattern signal. Simultaneously, the engine controller drives the optical scanning device
16
to form images on the photoreceptor belt
14
whenever the counted time is consistent with the image transfer time.
However, a one-time circulation cycle of the photoreceptor belt
14
can be changed according to time. The circulation cycle of the photoreceptor belt
14
can be changed according to variations in power transmitted to the photoreceptor belt
14
, a change in ambient temperature, or a change in the total length of the photoreceptor belt
14
due to aging. A variation in the circulation cycle of the photoreceptor belt
14
depending on the above factors can increase with an increase in the total length of the photoreceptor belt
14
.
When the circulation cycle of the photoreceptor belt
14
is changed by the above-described factors, the generation interval of the recognition pattern arrival signal is also changed. Consequently, according to the conventional paper pick-up method, the interval between sheets of paper
31
traveling along the paper transfer path
34
is also changed according to a variation in the generation interval of the recognition pattern arrival signal. In particular, when an optical scanning interval for each page and a paper pickup interval corresponding to the optical scanning interval are set to be short to increase printing speed, part of a preceding sheet of paper
31
traveling along the paper transfer path
34
may overlap the following sheet of paper even by a small variation in the circulation cycle of the photoreceptor belt
14
, resulting in a printing error.
SUMMARY OF THE INVENTION
To solve the above problem, it is an object of the present invention to provide a paper supply control apparatus and paper supply method in a printer, for controlling the time for picking up a sheet of paper from a paper feeding cassette in response to variations in the circulation cycle of a photoreceptor belt so that the interval between transferred sheets of paper is maintained at or over a predetermined range.
To achieve the above object of the present invention, there is provided a paper supply controlling apparatus in a printer, comprising: a pickup roller for picking up sheets of paper loaded in a paper feeding cassette and transferring the picked-up sheets of paper to a paper supply path leading to a transfer unit in a printer; a pickup roller driving portion for driving the pickup roller; a recognition pattern detecting sensor for detecting the passage of a recognition pattern formed on a circulating photoreceptor belt and outputting a recognition pattern arrival signal; and a paper pickup timing correction portion for determining a variation in the circulation cycle of the photoreceptor belt from the generation interval between the recognition pattern arrival signals, and controlling the pickup roller driving portion so that the time for picking up a sheet of paper from the paper feeding cassette on the basis of the time when the recognition pattern arrival signal is received is compensated for using the variation.
To achieve the above objective of the present invention, there is also provided a paper supplying method in a paper supply controlling apparatus, the method comprising the steps of: (a) setting as initial values a reference value of the circulation cycle of the photoreceptor belt, and reference times of the time for sequentially picking up sheets of paper on the basis of the time when the recognition pattern arrival signal is received; (b) determining whether the recognition pattern arrival signal is received; (c) calculating the generation time interval between a currently-input recognition pattern arrival signal and a previously-input recognition pattern arrival signal, if it is determined in step (b) that the recognition pattern arrival signal is received; (d) obtaining a paper pickup time correction value by subtracting the generation time interval obtained in step (c) from the reference value of the circulation cycle; (e) calculating a paper pickup correction time by adding the paper pickup time correction value to each of the paper pickup reference times; and (f) supplying sheets of paper by driving the pickup roller whenever the paper pickup correction times come on the basis of the time when the recognition pattern arrival signal is received.
REFERENCES:
patent: 4541711 (1985-09-01), Takahashi
patent: 4589765 (1
Brase Sandra
Samsung Electronics Co,. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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