Electrophotography – Machine operation – Having power supply
Reexamination Certificate
1999-08-09
2001-01-23
Chen, Sophia S. (Department: 2852)
Electrophotography
Machine operation
Having power supply
C219S216000, C219S490000, C399S037000, C399S043000, C399S251000
Reexamination Certificate
active
06178299
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of controlling a power supply to heat sources of a printer and an apparatus therefor, and more particularly, to a method of controlling the power supply to heat sources of a printer in which the power supply is controlled so that the individual heat sources maintain their desired operating temperatures while periods of power supply to the individual heat sources do not overlap all at once.
2. Description of the Related Art
FIG. 1
is a schematic diagram illustrating a general liquid electrophotographic printer.
Referring to
FIG. 1
, in a liquid electrophotographic printer, a reset device
15
, light scanning devices
16
, developing devices
17
, a drying unit
18
, and a transfer unit
20
are disposed along the circulation path of a photosensitive belt
14
circulated by a plurality of rollers
11
,
12
and
13
.
In a printing operation, first, the light scanning device
16
scans a light beam along the photosensitive belt
14
circulating past the reset device
15
. An electrostatic latent image is formed on the photosensitive belt
14
by the scanning of light. The electrostatic latent image is developed with a developer supplied from the developing device
17
. The color image formed on the photosensitive belt
14
is first transferred to a transfer roller
21
as the photosensitive belt
14
continues to advance. Then, the image on the transfer roller
21
is then transferred to a paper
23
when the transfer roller
21
and a fixing roller
22
rotate in contact with each other while causing the paper
23
interposed therebetween to advance.
In the above printer structured so as to perform the above printing operation, there are prerequisite conditions for normal printing operations. In the case of the transfer unit
20
, primarily, the surfaces of transfer roller
21
and the fixing roller
22
, must be maintained at appropriate preset temperatures. In addition, two heating rollers
18
b
and
18
c
must be maintained at a given temperature, since the two heating rollers
18
b
and
18
c
periodically evaporate the liquid carrier absorbed in a drying roller
18
a
while rotating in contact with the drying roller
18
a
. Here, the drying roller
18
a
absorbs the liquid carrier remaining on the photosensitive belt
14
while leaving the image forming toner of the liquid developer, supplied from the developing device
17
, on the photosensitive belt
14
for developing an electrostatic latent image.
FIG. 2
shows conventional controlling circuits for controlling the power supply to heaters
19
b
,
19
c
,
21
a
and
22
a
installed in the rollers
18
b
,
18
c
,
21
and
22
, so that respective heating temperatures required for performing such a printing operation are maintained.
In
FIG. 2
, the first heater
21
a
is intended to heat the transfer roller
21
, the second heater
22
a
is intended to heat the fixing roller
22
, and the third and fourth heaters
19
b
and
19
c
are intended to heat the drying unit
18
.
The controlling circuits for controlling the power supply to the individual heaters
19
b,
19
c
,
21
a
and
22
a
comprise: switch devices
31
,
32
,
33
and
34
, capable of connecting or disconnecting power from a power supply unit
30
to the respective heaters
19
b
,
19
c
,
21
a
and
22
a
; thermal sensors
41
,
42
,
43
and
44
for generating information concerning the temperatures of the respective heat-supplied objects corresponding to the heaters
19
b,
19
c,
21
a
and
22
a;
and, temperature controllers
51
,
52
,
53
and
54
for controlling the on/off operations of the switch devices
31
,
32
,
33
and
34
according to the information supplied by the thermal sensors
41
,
42
,
43
and
44
. Such power supply controlling circuits are provided for the respective heaters
19
b,
19
c,
21
a
and
22
a,
independently. Therefore, there may be a time or a period when all the switch devices
31
,
32
,
33
and
34
are turned on while the temperature controllers
51
,
52
,
53
and
54
individually control the on/off operations of the switch devices
31
,
32
,
33
and
34
so as to maintain the set temperatures of the respective heat-supplied objects. When all the switch devices
31
,
32
,
33
and
34
are turned on, the instantaneous power to be supplied by the power supply unit
30
increases. Consequently, such conventional power supply controlling circuits must be provided with a power supply unit
30
which has a power capacity much larger than that the mean power required for continuous operation. Power supply lines must be compatible with the maximum instantaneous current so as to supply the instantaneous maximum power when all the switch devices
31
,
32
,
33
and
34
are turned on, and such conventional circuits must satisfy a higher equipment requirement.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide a method of controlling the power supply to heat sources of a printer and an apparatus therefor which can perform temperature control for maintaining the desired temperatures of the heat-supplied objects while reducing instantaneous maximum power consumption.
Accordingly, to achieve the above objective, there is provided a method of controlling the power supply to heat sources of a printer, which comprises a heat generating portion having a plurality of heat sources, a power supply unit, and a power supply controller for controlling the power from the power supply unit to the heat generating portion, including the steps of: a) grouping predetermined heat sources into a first group, and grouping all or part of the remaining heat sources not belonging to the first group, among the heaters composing the heat generating portion, into a second group for adjusting periods of power supply to the heaters belonging to the heat generating portion; b) controlling the power supply to the heat sources belonging to the first group for controlling temperatures of the heat sources belonging to the first group while disconnecting the power supply to the heat sources belonging to the second group for a predetermined first time; c) disconnecting the power supply to the heat sources belonging to the first group for a predetermined second time after the first time has passed, and controlling the power supply to the heat sources belonging to the second group for controlling temperatures of the heat sources belonging to the second group; and d) repeating step b) and step c) at least once.
It is preferable that the heat generating portion comprises a first heat source for heating a transfer roller that transfers a toner image formed on a photosensitive medium to a paper, a second heat source for heating a fixing roller that rotates while pressing against the transfer roller so that the toner image transferred to the transfer roller can be securely fixed to the paper, and third and fourth heat sources installed in a drying unit for absorbing and evaporating liquid carrier remaining on the photosensitive medium. The second heat source, which requires the largest power among the four heat sources during printing, is grouped into the first group, and the first, third, and fourth heat sources are grouped into the second group.
According to one aspect of the present invention, there is provided a method of controlling the power supply to heat sources of a printer. The printer comprises: a heat generating portion having a first heat source for heating a transfer roller, which transfers a toner image formed on a photosensitive medium to a paper; a second heat source for heating a fixing roller, which rotates while pressing against the transfer roller so that the toner image transferred to the transfer roller can be securely fixed; third and fourth heat sources installed in a drying unit for absorbing and evaporating liquid carrier remaining on the photosensitive medium; a power supply unit; and, a power supply controller for controlling the power supply from the power supply unit to
Chen Sophia S.
Samsung Electronics Co,. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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