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BACKGROUND OF THE INVENTION
The present invention relates to a facsimile transceiver, printer, copier
or similar image forming apparatus and, more particularly, to a multiplex
image forming apparatus which is the combination of such apparatuses.
An image forming apparatus of the type described generally includes means
for preventing dew condensation from occurring thereinside. Such anti-dew
condensation means is especially indispensible in environments which cause
the room temperature to sharply change, e.g., in cold districts. The
anti-dew condensation means is usually implemented as a heater
incorporated in an AC power source line. It is a common practice to use,
for example, a cord heater or a cement resistor as the anti-dew
condensation means. Specifically, when a power switch is turned off, an
opposite contact associated with the power switch is closed to energize
the heater. The heater is arbitrarily located in the vicinity of a lens,
mirror or similar part whose thermal conductivity is low or a metallic
member having a substantial mass, e.g., the shaft of a photoconductive
element or that of a roller. Since an AC power source in the form of a
primary circuit is incorporated in the apparatus, such a heater makes it
difficult to isolate the primary circuit from a secondary circuit for
eliminating noise terminal voltage and radiation noise. Moreover, the
conventional heater is susceptible to noise generated on the AC power
source line and extraneous noise ascribable to, for example, a
thunderbolt, resulting in complicated countermeasures.
A multiplex image forming apparatus having multiple functions, e.g.,
facsimile function, printer function and copier function is a recent
achievement. A Japanese Patent Laid-Open Publication (Kokai) No.
57870/1989, for example, discloses a multiplex image forming apparatus
which is the combination of a facsimile transceiver and a copier. In such
an apparatus, even when a power source for the copier is turned off, it is
automatically turned on when the facsimile transceiver receives data from
a remote station. Then, the copier prints out the received data. This type
of apparatus is provided with a main power source and a scanner power
source. The main power source includes a detector responsive to the AC
power source line. When the facsimile transceiver operates in a receive
mode at night, a fixing heater and other constituents of the apparatus to
be not used are deactivated to save power while preserving the facsimile
function. However, since a control circuit incorporated in the apparatus
is active at all times, a noticeable power saving effect cannot be
expected. Further, with this conventional apparatus, it is impossible to
reduce the power consumption by the DC power source during reception at
night. In addition, in the receive mode operation at night, a cooling fan
has to be rotated to cope with heat generation ascribable to power
consumption, resulting in the increase in noise.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to eliminate the
problems particular to a conventional multiplex image forming apparatus as
discussed above.
It is another object of the present invention to provide a multiplex image
forming apparatus which constantly remains in a standby state for multiple
functions including a copier function, facsimile function and a printer
function and, in a night receive mode, fully deactivates devices to be not
used, thereby saving power and reducing noise.
In accordance with the present invention, a multiplex image forming
apparatus comprises a power source for a copier, an application extending
section allowing a facsimile function to be combined with the apparatus,
and a power source for a multiplex configuration for driving the
application extending section, a first and a second power source switch
located at an input section preceding the two power sources, a detecting
circuit connecting to the first power source switch for detecting turn-on
and turn-off of the switch, and detection signal output control means for
outputting a detection signal fed from the detecting circuit only when the
second power source switch is turned on and the first power source switch
is turned off.
Also, in accordance with the present invention, a multiplex image forming
apparatus comprises a power source for a copier, an application extending
section capable of combining a facsimile function with the apparatus, and
a power source for a multiplex configuration for driving the application
extending section, a first and a second switch located at an input section
preceding the two power sources, and anti-dew condensation means operable
only when the second power source switch is turned on and the first power
source switch is turned off.
Further, in accordance with the present invention, a multiplex image
forming apparatus comprises a power source for a cipier, an application
extending section capable of combining a facsimile function with the
apparatus, and a power source for a multiplex configuration for driving
the application extending section, a first and a second switch located at
an input section preceding the two power sources, and power supply path
interrupting means for interrupting part of power supply paths only when
the second power switch is turned on and the first power source switch is
turned off.
Moreover, in accordance with the present invention, a multiplex image
forming apparatus comprises a power source for a copier, an application
extending section capable of combining a facsimile function with the
apparatus, and a power source for a multiplex configuration for driving
the application extending section, a cooling fan included in the power
source of a copier, a heat generating member whose heat generating state
changes, temperature detecting means for detecting the temperature of the
heat generating member, and fan rotation speed control means for changing
the rotation speed of the cooling fan in matching relation to the
temperature detected by the temperature detecting means.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present
invention will become more apparent from the following detailed
description taken with the accompanying drawings in which:
FIG. 1 is a block diagram schematically showing a power source circuit
included in a multiplex image forming apparatus embodying the present
invention;
FIG. 2 is a diagram showing a specific construction of a main switch OFF
detecting circuit included in the embodiment;
FIG. 3 is a flowchart demonstrating a specific operation of a main control
circuit also included in the embodiment and which pertains to a mode 3;
FIG. 4 is a flowchart demonstrating a specific operation pertaining to a
mode 4;
FIG. 5 is a flowchart showing a specific print ready sequence in a night
on-line mode;
FIG. 6 is a flowchart representative of a print start sequence in the night
on-line mode;
FIG. 7 is a flowchart representative of a print end sequence in the night
on-line mode;
FIG. 8 is a block diagram schematically showing an alternative embodiment
of the present invention;
FIG. 9 is a circuit diagram showing a specific construction of a main
switch OFF detecting circuit included in the embodiment of FIG. 8;
FIG. 10 is a block diagram schematically showing control circuitry included
in a multiplex digital copier;
FIG. 11 is a block diagram schematically showing a scanner section included
in the digital copier;
FIG. 12 is a block diagram schematically showing a specific construction of
an electric part control section;
FIG. 13 is a block diagram schematically showing a specific construction of
an application extending section;
FIG. 14 is a vertical section showing the general construction of a
multiplex digital copier;
FIG. 15 is a plan view showing the construction of a writing section
included in the digital copier of FIG. 14;
FIG. 16 is a side elevation of the writing section;
FIG. 17 is a perspective view of the application extending section;
FIG. 18 is a block diagram schematically showing a specific construction of
a main control circuit included in an electric part control section;
FIG. 19 is a block diagram schematically showing part of the main control
circuit assigned to operation control; and
FIG. 20 is a block diagram schematically showing another part of the main
control circuit assigned to sequence control.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1-7 and 10-20, a multiplex image forming apparatus
embodying the present invention will be described. To better understand
the essential part of the embodiment, the general construction of a
multiplex image forming apparatus in the form of a digital copier will be
described with reference to FIGS. 10-20. As shown in FIG. 10, the
multiplex digital copier is generally made up of an AC input section 1, a
DC copy power source 2 assigned to a copier function, a DC multiplex power
source 3 assigned to a multiplex configuration, a scanner section 4, an
electric part control section 5, an application extending section 6 for
the multiplex function, and a printer section 7. As shown in FIG. 14, the
printer section 7 has a writing section, an electrophotographic process
section 9, and a paper processing section 10. FIGS. 11-13 show
respectively specific constructions of the scanner section 4, electric
part control section 5, and application extending section depicted in FIG.
10.
As shown in FIGS. 10-14, the scanner section 4 has a first scanner 12
movable at a particular speed matching a magnification, and a second
scanner 13 movable at one half of the speed of the first scanner 12. The
first scanner 12 has a light source 12a, a reflector 12b and a first
mirror 12c in close proximity to the underside of a glass platen 11 which
is positioned in an upper portion of the copier body. The second scanner
13 has a second mirror 13a and a third mirror 13b. The scanners 12 and 13
scan a document, not shown, laid on the glass platen 11 while illuminating
it. The resulting reflection, or imagewise light, is routed through a lens
14 to a CCD (Charge Coupled Device) image sensor or primary solid-state
image pick-up device 15 to be thereby photoelectrically transduced to an
analog image signal. An image processor (IPP) 16 corrects the analog image
signal with respect to the quantity of light, black level, and shading and
then produces a corresponding digital image signal. The digital image
signal is applied to an image processing unit (IPU) 17 to be subjected to
various kinds of processing, e.g., high frequency enhancement or MTF
(Modulation Transfer Function) correction, rate conversion or
magnification change, gamma correction, and data depth conversion (8
bits/4 bits/1 bit). The processed digital image signal is fed to a scanner
control circuit 19 either directly or by way of a memory unit (MEM) 18 and
then applied to a main control circuit 20. The scanner control circuit 19
and main control circuit 20 are connected by a command interface and a
parallel interface. The command interface is implemented by a full-duplex
system using an optical fiber while the parallel interface is assigned to
image signals and others which need high-speed processing.
The scanner control circuit 19 is located at the left-hand side of the
scanner section 4, as viewed in FIG. 10, so as to totally control the
scanner section 4. Specifically, as shown in FIG. 11, a cooling fan 21, a
home position (HP) sensor 22, a stabilizer 23, a scanner motor 24 and an
automatic document feeder (ADF) control board 25 are connected to the
scanner control circuit 19. The scanner control circuit 19, therefore,
effects various kinds of control including control of timings relating to
the document handling and reading, i.e., the control of the rotation of a
carriage drive motor, light to issue from a lamp, temperature of a lamp
heater, and interface to the ADF, as well as the control of image data
switching, magnification change, image editing, and tonality. Since the
radiation noise ascribable to high-speed signals has substantial energy,
the embodiment has various positive implementations against such noise,
e.g., a gate array, shielded parallel interface, control circuitry with a
shield cover, and reinforced connection of metallic elements. The scanner
section 4 further includes an operation unit 26 for copying. While the
operation unit 26 communicates with the main control circuit 20, use is
made of an optical fiber for the communication in order to eliminate
noise.
While the printer section 7 has the previously mentioned writing section 8,
electrophotographic process section 9, and paper processing section 10,
the following description will mainly concentrate on the writing section
8. Image data generated by the scanner section 4 (or the application
extending section 6 which will be described) is steered by the main
control circuit 20 to the writing section 8. In the writing section 8, a
laser beam scans a photoconductive drum 27 by raster scanning to write the
image data thereon.
Specifically, as shown in FIGS. 15 and 16, light issuing from a
semiconductor laser 28 is converted to a parallel beam by a collimator
lens 29 and then trimmed by an aperture 30 to have a predetermined shape.
The trimmed laser beam is incident to a polygonal mirror 32 after being
compressed by a first cylindrical lens 31 in the subscanning direction.
The polygonal mirror 32 is rotated at a constant speed in a predetermined
direction. The rotation speed of the polygonal mirror 32 is determined by
the rotation speed and writing density of the drum 27 and the number of
faces of the mirror 32. The laser beam incident to the polygonal mirror 32
is steered by the mirror 32 to sequentially reach f-theta lenses 33a and
33b. The laser beam coming out of the f-theta lenses 33a and 33b and
having a constant angular velocity is focused onto the surface of the drum
27 with a minimum spot diameter and scans the surface of the drum 27. The
f-theta lenses 33a and 33b also serve to correct errors ascribable to the
irregularity in the positions of the faces of the polygonal mirror 32. At
the same time, the laser beam passed the lenses 33a and 33b is guided to a
synchronization detecting section 35 by a mirror 34. The resulting output
of the detecting section 35 is propagated through an optical fiber, not
shown, to a sensor portion included in the main control section 20. As a
result, one line of image data is outputted on the elapse of a
predetermined period of time after a synchronization (hereinafter
abbreviated as sync) signal indicative of the beginning in the main
scanning direction has been generated. Such a procedure is repeated to
complete a single image.
To enhance enrich tonarity, the image data is applied to a PWM (Pulse Width
Modulation) control board 36 also. In the PWM control board 36, when the
input parallel image data are to be converted to serial image data for
driving the laser or laser diode (LD) 28, a delay line and a programmable
logic device (PLD) effect pulse width modulation with the parallel data
and deliver the modulated data to an LD control board 37. As a result, an
LD driver drives the laser 28 over a period of time matching a designated
pulse width. A photodiode, not shown, is built in the laser 28 for the
purpose of monitoring the laser beam. By monitoring the laser beam, it is
possible to stabilize the quantity of the beam, to detect faulty laser
drive, to increase or decrease the quantity of beam, and to correct the
duration of laser drive. The PWM control board 36 suffers from radiation
noise having substantial energy since elements having a rapid rising and
falling capability are used to control pulse widths of nanosecond order.
In light of this, the PWM control board 36 is confined in a shield case
and is connected to the main control circuit 20 by a shield cable. A
polygon motor 32a for driving the polygonal mirror 32 is rotated at a
constant speed higher than 20,000 r.p.m so as to eliminate the
irregularity in the writing pitch in the main scanning direction. A driver
assigned to the polygon motor 32a is located at the left-hand side of the
motor 32a to make the wiring therebetween as short as possible. A stream
of air for cooling the motor 32a is not implemented by the atmosphere
inside the machine in order to protect the polygonal mirror 32 from
impurities including a silicon gas ascribable to image fixation and toner
particles.
The above-described major electric circuitry relating to the writing
section 8 is located at the left-hand side of the drum 27, as viewed in
FIG. 14. The electrophotographic process section 9 and paper processing
section 10 are disposed in the vicinity of the writing section 8. The
process section 9 has a charger 38, a developing section 39, an image
transfer section 40, and a cleaning section 41 which face the surface of
the drum 27. The paper processing section 42 has a paper feeding section
42, a transporting section 43, a fixing section 44, and a discharging
section 45.
The application extending section 6 will be described hereinafter. To begin
with, why this section 6 is desirable will be described. Digital PPC is
advantageous in that it processes an image by a digital electronic circuit
and can be readily connected to another electronic equipment. On the other
hand, office automation equipment including facsimile machines and word
processors are extensively used today. There is an increasing demand for a
systematic product having a copier at the center thereof, e.g., multiplex
facsimile, word processor or electronic file equipment. The application
extending 6 meets such a need and allows the user to achieve advanced
multiplex functions by simple operations. The construction of the
application extending section 6 will be described with reference to FIGS.
13 and 17.
The application extending section 6 has an operation unit 46 and an
application base board 47 which are connected to the main control circuit
20. A facsimile (FAX) board 48, a print board 49 and a file board 50 are
connected to the application base board 47. A handset 51 and a telephone
line 52 are connected to the FAX board 48. A memory (MEM) card 53, a font
card 54, FDD 55 and a host computer 56 are connected to the print board
49. An HDD 57 and an ODD 58 are connected to the file board 50. An LCDC
board, LCD and touch panel, not shown, are connected to operation unit 46.
The operation unit 46 has a 256.times.400 dots liquid crystal display
panel, transparent touch switches, a control circuit for controlling the
switches, and a unit implementing back illumination. The operation unit 46
is connected to the main control circuit 20 by an optical fiber for
implementing command interface. Regarding display data, the operation unit
46 is interfaced to the application base board 47 by parallel interface.
Even when one or both of the print board 49 and FAX board 48 are added to
the copier, the application base board 47 performs control relating to
display and input operations in combination with the operation unit 46 by
smoothly mediating between them and the main CPU of the main control
circuit 20. The FAX board 48 serves a FAX function via the telephone line
52. Particularly, in the event of reception at night, received information
is stored in the HDD 57 under the control of the application base board
47. The print board 49 has a function of an off-line printer, e.g., an SIO
or CENTRO on-line printer, FDD 55, or MEM card 53. The file board 50 reads
and writes data in a medium with which the HDD 57 or the ODD 58 is
operable. Since the FDD 55 and ODD 58 are frequently operated by the user,
they are positioned just below the operation unit 26, i.e., at a desirable
level for manipulation and operated at the front. The font card 54 and MEM
card 53 which will be operated less frequently than the FDD 55 and ODD 58
are operated at the side although they are located at substantially the
same level as the latter.
When the above-stated boards for a multiplex configuration are simply
arranged in unoccupied spaces, complicated wirings will increase, buses
will become susceptible to noise, and radiation noise will increase. In
the embodiment, such boards are disposed in the space available in the
writing section 8 and a substantially hermetic space formed between the
scanner section 4 and the writing section 8. Again, the boards communicate
with the main control circuit 20 over an optical fiber and a shield cable
to reduce the influence of noise.
As shown in FIG. 12, the main control section 20 included in the control
section 5 is connected to the scanner section 4 and application extending
section 6 as well as other sections for controlling the scanner and the
facsimile and other multiplex equipment. In addition, the main control
section 20 is connected to a DC control board 59, a sorter control board
60, and a two-side control board 61. Sensors 62 including a paper size
sensor and a tray set sensor, a suction fan 63, a transport fan 64, and a
drive control section 65 for effecting various copy modes are connected to
the DC control board 59, whereby operations in various copy modes
including ordinary one are controlled. Sensors 66 and a drive control
section 67 for interrupting an operation under way are connected to the
sorter control board 60, thereby controlling the operation of a sorter.
Connected to the two-side control board 61 are sensors 68 responsive to
the discharge and release of paper sheets and drive control sections 69
assigned to a two-sided copy mode. Motor drive boards 70 and 71, a high
tension power source 72, sensors 73, fans 74 including an exhaust fan,
counters 75 including a key counter, and a thermistor 76 associated with
fixation are connected to the main control circuit 20, whereby the scanner
operations and printing operations are totally controlled.
The construction of the man control circuit 20 will be described with
reference to FIGS. 18-20. As shown, the main control circuit 20 has two
CPUs 77 and 78 as copier control units; the CPUs 77 and 78 are assigned to
sequence control and operation control, respectively. The CPUs 77 and 78
are connected together by a serial interface.
To begin with, sequence control to be executed by the CPU 77 will be
described. The sequence sets and outputs various conditions relating to
the paper transport timings and the formation of an image. Connected to
the CPU 77 are a paper size sensor 79, sensors 80 responsive to the
discharge and register of a paper sheet, a two-sided copy unit 81, a high
tension power source unit 82, drivers 83 for driving relays, solenoids,
motors and fans, a sorter unit 84, a scanner unit 85 (including the laser
unit), and an image control circuit 86. The paper size sensor 79 senses
the size and orientation of paper sheets stacked on a paper cassette to
generate corresponding electric signals. The sensors 80 include sensors
relating to paper transport, sensors associated with supplies, e.g., an
oil end sensor and a toner end sensor, and sensors responsive to the
faults of the machine, e.g., a door open sensor and a fuse sensor. The
two-sided copy unit 81 includes a motor for positioning paper sheets in
width, a paper feed clutch, solenoids for steering a paper sheet, a paper
presence/absence sensor, a side fence position sensor for positioning
paper sheets in width, and sensors responsive to paper transport. The high
tension power source unit 82 applies a predetermined high voltage to each
of a main charger, transfer charger, separation charger and a bias
electrode for development by a particular duty resulted from PWM control.
The drivers 83 drive the paper feed clutch, register clutch, counters,
motors, fans, toner supply solenoid, power relays, fixing heater, etc.
The sorter unit 84 is connected to the CPU 77 by an optical serial
interface and, in response to signals from the sequence, transports paper
sheets at predetermined timings to consecutive bins thereof. The sorter
unit 84 receives analog signals which are a signal representative of a
fixing temperature, the output of the photosensor, an LD monitor output,
and an LD reference voltage. In response to the output of the thermistor
located at the fixing station, the sorter unit 84 ON/OFF controls or
controls the phase of the heater. Regarding the photosensor output, a
photosensor pattern formed at a predetermined timing is inputted via a
phototransistor to determine the density of the pattern. The determined
density is used to ON/OFF control the toner supply clutch for controlling
toner density and to detect a toner end condition. The scanner unit 85
uses an analog-to-digial (A/D) converter and the analog output of the CPU
77 as a mechanism for maintaining the LD output power constant.
Specifically, the scanner unit 85 controls the LD power such that the
voltage monitored on the turn-on of the LD coincides with a predetermined
reference voltage (which is selected to set up an LD output of 3 mW).
FIG. 19 shows the operation control to be executed by the CPU 78. As shown,
a plurality of serial ports a, a calendar IC 87, a gate array 88 and an
address decoder 89 are connected to the CPU 78. Connected to the serial
ports a are an operation unit 90, a scanner control circuit 91, an
application 92, and an editor unit 93. The operation unit 90 has a display
for displaying operator's key inputs and the states of the copier and
informs the CPU 78 of key inputs by serial transmission. In response, the
CPU 78 determines whether or not to turn on the display of the operation
unit 90 and informs operation unit 90 of the result of decision by serial
transmission. Then, a CPU built in the operation unit 90 turns on or turns
off the display. The scanner control circuit 91 sends to the CPU 78
information relating to the control of a scanner servo motor, image
processing and image reading. In response, the CPU 78 executes serial
transmission processing and interface processing between itself and the
ADF. The application 92 interfaces the CPU 78 to external equipment, e.g.,
facsimile transceiver or printer by interchanging predetermined
information. The editor unit 93 serially sends masking data trimming data,
image shifting data or similar image editing data entered by the operator
to the CPU 78. The calendar IC 87 stores day and time and allows the CPU
78 to call then any time. Hence, only if the display of the current time
on the display and the ON time and OFF time of the machine are set up
beforehand, the machine can be controlled ON and OFF by a timer.
On receiving a select signal from the CPU 78, the gate array 88 delivers
image data (DATA0-DATA7) and a sync signal to one of three different
directions, as follows. A first direction is from the scanner control
circuit 91 to the image control circuit 86, FIG. 20. In this case, the
gate array 88 transfers 8-bit data (or 4-bit or 1-bit data) fed from the
scanner control circuit 91 to the image control circuit 86 while
synchronizing them to a sync signal PSYNC from the scanner unit 85. A
second direction is from the scanner control circuit 91 to the
applications 92. In this direction, the gate array 88 transfers an image
signal in the form of 1-bit (binary) data from the scanner control circuit
91 to the application 92 in parallel. Then, the application 92 feeds the
image data to a printer or similar output terminal connected to the
copier. A third direction is from the application 92 to the image control
circuit 86. In this case, the application 92 transfers an image data in
the form of 1-bit (binary) data from a facsimile machine or similar input
terminal to the image control circuit 86 while synchronizing them to the
sync signal PMSYNC.
Hereinafter will be described specific constructions of essential part of
the embodiment with reference to FIGS. 1-7.
As shown in FIG. 1, a first power source switch 94 and a second power
source switch 95 are interposed between the DC copy power source 2 and DC
multiplex power source 3 and the AC input section 1 preceding the power
sources 2 and 3. The AC input section 1 consists of a noise filter 1a, a
circuit breaker 1b, an AC drive board 1c, a temperature fuse 1d, and a
fixing heater 1e. A main switch OFF or SWOFF detecting circuit 96 is
connected to the first power source switch 94 to sense the ON and OFF
states of the switch 94. Detection signal output control means, not shown,
is contained in the main SWOFF detection circuit 96. This control means
allows a detection signal or main SWOFF detection signal to be fed to the
main control circuit 20 only when the second power source switch 95 is ON
and the first power source switch 94 is OFF.
The scanner section 4 and printer section 7 are provided with a heater 97,
FIG. 11, for eliminating dew condensation. The main SWOFF detecting
circuit 96 sends a heater signal to the heater 97 such that the heater 97
operates only when the second power source switch 95 is ON and the first
power source switch 94 is OFF. A switching circuit 98 plays the role of
power supply path interrupting means for interrupting part of the power
supply paths only when the second power source switch 95 is ON and the
first power source switch 94 is OFF. The switching circuit 98 interrupts
the power supply paths in a document handling section, document reading
section, and user-oriented operating section, not shown, while turning off
a DC power source cooling device, not shown.
Further, the copier of the embodiment has means for stopping the execution
of user's manipulation, second power supply path interrupting means, and
control means for interrupting a receive mode at night. The user's
manipulation execution interrupting means stops the execution of control
relating to the user's operations, except for on-line control, when the
main SWOFF detection signal is generated. The second power supply path
interrupting means interrupts, when the switching circuit 98 interrupts
part of the power supply paths, other power supply paths. The receive mode
interruption control means inhibits at least the fixing heater and rotary
members from operating in response to the output signal of the previously
mentioned detection signal output control means, except for print-out at
night.
FIG. 1 shows the power source circuit having the AC power source 1, DC copy
power source 2, and DC multiplex power source 3. FIG. 2 depicts a specific
construction of the main SWOFF detecting circuit 96 included in the DC
copy power source 2. The various means of the embodiment described above
will be sequentially described specifically.
A commercially available power source (AC 100 V, 50/60 Hz) is fed to the
noise filter 1a via a power source cord. This is to prevent the machine
from malfunctioning due to extraneous noise superposed on the power source
line and to prevent other equipment from malfunctioning due to intrinsic
noise introduced in the power source line. The circuit breaker 1b follows
the noise filter 1a for protecting the copier from overloads and other
faults. The first power source switch 94, second power source switch 95
and AC drive board 1c are connected in parallel to the output of the
circuit breaker 1b. The first power source switch 94 is operated daily by
the user while the second power source switch 95 is not done so. The AC
drive board 1c turns on a triac included in an SSR by a signal SSRON to
control the heater, thereby maintaining the heat roller temperature at a
fixing level. A signal RAON controls a relation which shuts off the power
supply to the heater when the heater control falls in an unusual state.
The AC drive board 1c does not operate unless the switching circuit 98 of
the power source 2 operates.
The first and second power source switches 94 and 94 are operable in four
different modes, as listed in Table 1 below.
TABLE 1
______________________________________
MODE 1 MODE 2 MODE 3 MODE 4
______________________________________
1ST SWITCH OFF ON OFF ON
2ND SWITCH OFF OFF ON ON
______________________________________
Mode 1: Power is not fed to the switching circuit 98 of the DC copy power
source 2, so that no DC output appears. In this condition, the fixing
heater remains in an OFF state. Therefore, the main SWOFF detecting
circuit 96 which operates at +24 V, as shown in FIG. 2, is not operated,
maintaining the machine totally in an OFF state.
Mode 2: The switching circuit 98 is operated to output DC power, enabling
heater control. At this instant, since the AC power source shown in FIG. 2
is not fed, PC1 and, therefore, Q.sub.1 is OFF, so that Q.sub.2, Q.sub.4
and Q.sub.5 are also OFF. In this condition, RA does not turn on with the
result that Vcc (+5 V) is applied to the scanner section 4. Hence, the
heater signal and main SWOFF detection signal are not outputted in an ON
state. On the other hand, since Q.sub.2 is OFF, Q.sub.3 is turned on to
turn on a self-cooled fan 99.
Mode 3: The switching circuit 98 is operated, enabling heater control.
Since the main SWOFF detecting circuit 96 is an ON state due to the supply
of AC, PC1 and Q.sub.1 are ON to render Q.sub.2, Q.sub.4 and Q.sub.5 ON.
On the other hand, Q.sub.3 is OFF. In this condition, RA is ON to prevent
Vcc from reaching the scanner section 4, whereby the self-cooled fan 99 is
not rotated. Instead, the heater signal is in an ON state to drive the
heater 97, and the main SWOFF signal is also in an ON state and fed to the
main control circuit 20. The mode 3 implements the previously mentioned
dew condensation preventing mans.
Mode 4: This mode is identical with the mode 2 as to the operation and will
not be described to avoid redundancy.
The modes 1, 2 and 4 are identical with modes which occur in an ordinary
image forming apparatus. The mode 3 will be described more specifically
hereinafter.
In the mode 3, since RA is ON, +5 V to the scanner section 4 is
interrupted. Hence, the scanner control circuit 19, FIG. 11, does not
rise, and drive signals meant for APSsol 100, ADFsol 101, (lamp)
stabilizer 23, cooling fan 21 and scanner motor 24 are OFF. In this
condition, power is substantially not consumed despite the supply of +24
V. As a result, the interruption of 5 V to the scanner section 4 reduces
the total load acting on the DC copy power source 2 by about 60%. Since
the entire scanner section 4 is held in an OFF state, dew is apt to
condense in the image reading section including mirrors, lens and CCD
array at night due to the fall of temperature. In light of this, the DC
copy power source 2 is fed to the heater 97 to prevent dew condensation by
heat. Since the heater 97 is implemented as a DC heater, it is isolated
from AC and, therefore, little susceptible to noise. This prevents the
heater 97 from effecting the other circuitry and from generating noise
terminal voltages. In addition, the heater 97 protects the photoconductive
drum and developing unit of the printer section 7 from dew condensation
which is likely to occur in ordinary printers.
In the mode 3, the main control circuit 20 is operated as follows. FIG. 3
demonstrates a specific operation of the main control circuit 20 in the
mode 3 which is included in part of a main routine. As shown, when the
switching circuit 98 of the DC copy power source 2 is operated, a main CPU
built in the main control circuit 20 does not execute the program until a
timer counts up a predetermined period of time long enough to fully
initialize the various systems. Then, the CPU determines whether or not a
main SWOFF flag is set, and, if it is not set, determines whether or not a
main SWOFF signal is being generated by the DC copy power source 2. If the
main SWOFF signal is absent, the CPU determines that an ordinary image
forming mode has been set up, and it delivers program start signals to the
various systems to thereby enable all the systems. If the main SWOFF
signal is being generated, meaning that a night mode is set up, the CPU
sets the main SWOFF flag. Then, the CPU cancels indetermined data from the
operating section and scanner section 4 (including ADF) to which power is
not fed, while causing the application to start up its program.
Thereafter, the CPU repeats the sequence of steps described so far and
determines whether or not an on-line mode is set by use of an on-line
flag. If the on-line flag is not set, the CPU determines whether or not
the copier is in an on-line state by referencing signals fed from the CPU
of the application. If the answer of this decision is negative, meaning
that the current state does not need operator's manipulation, the CPU
initializes the application and sequence. If the current state is an
on-line state, the CPU sets the on-line flag to allow the sequence and
application programs to continue. On receiving an initialize signal from
the CPU, the application and sequence each clears a RAM and all the ports
thereof to set up a false power interruption state. Thereafter, the CPU
clears the timer and does not repeat the routine thereafter. When the
operator turns on the first power source switch 94 in the mode 3 so as to
set up the mode 4, a procedure shown in FIG. 4 and also included in part
of the main routine is executed.
In FIG. 4, since the main SWOFF flag has been set in the program of FIG. 3,
the CPU determines whether or not the mode 3 has been cancelled by
referencing the main SWOFF signal. If it has been cancelled, meaning that
the operating section is being initialized with power being fed thereto,
the CPU waits until a timer counts up a predetermined period of time and
then enables the various systems. As the operator replaces the mode 3 with
the mode 4, the CPU sets the main SWOFF flag since the main SWOFF flag is
not set, i.e., the main SWOFF signal is generated. As a result, the
indetermined data of the operating section and scanner section 4 to which
power is not fed are cancelled. Subsequently, the CPU checks the on-line
flag to see if the applications are on-line applications, thereby
selecting respective night modes. In the night mode described above, when
the sequence is initialized, the fixing heater, control, polygon motor,
relay associated with the heater, cooling fan and so forth all are in an
OFF state. When the applications are initialized, FDD 55, ODD 58 and HDD
57 all are disenabled.
FIGS. 5-7 are representative of a specific print-out flow to be executed by
the CPU when the memory is over in the night on-line mode. As shown in
FIG. 5, on receiving a print request from the application, the CPU sets a
print request flag, sends a fixation control ON command and a polygon
motor ON command to the sequence, and | | |
