Electrophotography – Machine operation – Having power supply
Reexamination Certificate
2000-05-12
2002-06-18
Chen, Sophia S. (Department: 2852)
Electrophotography
Machine operation
Having power supply
C219S216000, C307S139000, C399S037000, C399S070000
Reexamination Certificate
active
06408148
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image processing apparatus, an image recording apparatus, a method for controlling the same, and a power supply apparatus used therein.
2. Related Background Art
Presently, in general, an image recording apparatus such as a printer indispensably requires a dual-output power supply which combines a large-capacity engine driving power supply (e.g., of 24V) for use in a steady operation and a small-capacity engine controlling power supply (e.g., of 3.3V).
Recently, in particular, there have been developed various technologies for saving energy in a wait state in a specific attempt to save on power in a wait state (during sleeping) in which the engine driving power supply is not necessary.
FIG. 1
is a circuit diagram showing one example of a configuration of a power supply system for an electrophotographic image recording apparatus by the present inventor. In this drawing, a reference numeral
1
indicates a commercial AC power supply, an alternating current from which is rectified by a diode-bridge
2
, a direct current from which is in turn smoothed by a capacitor
3
and then supplied to two converters.
That is, reference numerals
10
and
110
indicate respective transformers of these converters, being provided with primary windings
27
and
127
, secondary windings
28
and
128
, and control windings
29
and
129
, respectively, in such a configuration that the primary windings
27
and
127
have switching-element MOSFET's
7
and
107
connected thereto, respectively. On the side of the primary winding of the converter, reference numerals
4
and
104
indicate driving circuits comprised of controlling IC's for turning the respective FET's
7
and
107
ON and OFF and reference numerals
5
and
105
, the respective resistors. On the side of the secondary winding of the converter, reference numerals
16
and
116
indicate rectifying diodes and reference numerals
20
and
120
, smoothing capacitors, in such a configuration that one of the two converters which is installed at the upper stage feeds out +24V DC voltage and the other converter at the lower state, +3.3V DC voltage.
The controlling windings
29
and
129
for the converters have connected thereto rectifying diodes
9
and
109
, smoothing capacitors
8
and
108
, and resistors
6
and
106
respectively, thus supplying their DC outputs (Vcc) to driving circuits
4
and
104
respectively. The driving circuits
4
and
104
also have connected thereto photo-transistors of photo-couplers
12
and
112
respectively, in such a configuration that the anodes of light emitting diodes of the photo-couplers
12
and
112
are connected via resistors
23
and
123
to output terminals of the primary winding respectively, while the cathodes have constant-voltage diodes
24
and
124
respectively, gates of which are supplied with outputs (ref) of the secondary side output voltage divided by resistors
21
and
22
and resistors
121
and
122
respectively.
In
FIG. 1
again, a reference numeral
200
indicates an engine controller for the image recording apparatus and a reference numeral
300
indicates a relay for cutting off the power supply, a relay coil of which is connected with a transistor
301
controlled by the engine controller and a relay contact of which is connected to a heating means
400
of a fixing device and also between a triode AC switch (triac) and the commercial power supply. A reference numeral
600
indicates a relay for cutting the power supply, a relay contact of which is disposed on a DC power supply input line on the primary winding side of the upper stage converter and a relay coil of which is connected to a transistor
601
controlled by the engine controller
200
.
In the circuit of the above-described configuration, if the heating means
400
or the triac
500
fails, the relay
300
acts to prevent the AC power supply from being applied to the heating means
400
. In such a case, the engine controller
200
turns the transistor
301
ON and OFF to open and close the relay
300
. The engine controller
200
also drives and controls the printer engine, the heater driving circuit for controlling a quantity of electrification through the heater of the heating means, and the relays
300
and
600
.
The relay
600
acts to cut off power to the 24V power supply, while the engine controller
200
, in a constant lapse of time after the relevant printer terminates printing and enters the wait state, turns OFF the transistor
601
in order to open the relay
600
, thus cutting off power to the 24V power supply. To restart actual printing, that controller turns ON the transistor
601
to close the relay
600
, thus supplying power to the 24V power supply.
With such a configuration, the relay
600
can be opened in the wait (sleep) state to cut off power supplied to the 24V power supply, thus saving on power in that state.
An image recording apparatus which employs the above-described power-supply circuit has many circuit components used for cutting the power supply, which leads to such problems of an increased cost, an expanded packaging surface, and an enlarged apparatus.
There may also be such a method of, in the sleep state, changing an oscillation frequency to permit the power supply to engage in blocking oscillation, in order to lower the voltage level of the driving power supply, thus reducing the loss of energy required.
An example of such control method of blocking oscillation is described below with reference to
FIGS. 2 and 3
.
FIG. 2
shows an example of a circuit configuration of a power supply apparatus by the present inventor for a printer etc. Note here that the same reference numbers indicate the same parts in
FIGS. 1 and 2
.
The reference number
200
indicates the engine controller, which drives the printer engine, controls the engine, the heater driving circuit for controlling a quantity of electrification through the heater, and the relays.
This engine controller
200
is provided with three ports of an RLDR port connected to a cutting-off control circuit for the relay
300
, an FCHG port connected to a frequency control circuit for a power supply control IC
4
, and a VCHG port connected to a power-supply voltage control circuit.
The engine controller
200
sets the RLDR port High and Low to turn the transistor
301
ON and OFF, thus opening and closing the relay
300
.
A reference numeral
212
indicates a photo-coupler for transmitting a signal generated from the FCHG port of the engine controller
200
to the power-supply control IC
4
, thus changing for a frequency of the power-supply control IC
4
. Furthermore, to obtain a 3.3V output Vcc
2
from the 24V output Vcc
1
, three-terminal regulators
150
and
151
are provided, as well as a resistor
152
and a transistor
153
for switching Vref.
(Sleep state)
The following will describe operations in the sleep state.
When the printer terminates printing, the engine controller
200
sets the FCHG port Low, thus cutting off a current flowing through the photo-coupler
212
in a constant lapse of time (in the sleep state). With this, the FCHG port of the power-supply control IC
4
is connected to GND via a point P.
In this sleep state, as shown in
FIG. 3
, the oscillation frequency of the power-supply control IC
4
is decreased, thus reducing a switching loss of the power supply.
Furthermore, the engine controller
200
sets the VCHG port Low to turn OFF the transistor
153
, thus cutting off electrification to the resistor
152
. With this, the power supply is controlled such that a voltage obtained by dividing a Vcc
1
voltage with feedback resistors
21
and
22
may be equal to a reference voltage of a shunt regulator
24
.
When a current flows at the light emitting section of the photo-coupler
12
, the light emitting section is turned ON to permit the current to flow out of the F.B section of the power-supply control IC
4
. In response to this current, the power-supply control IC
4
controls its
Chen Sophia S.
Fitzpatrick ,Cella, Harper & Scinto
LandOfFree
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