Abstract:
An apparatus having a power supply section capable of outputting plural power supply voltages is provided with a sleep mode (energy-saving mode) for inhibiting at least one of the outputs from the power supply section in a wait state. Furthermore, an image forming apparatus such a printer is provided with a cut-off function for inhibiting at least one of the outputs from the power supply section supplied to a heater of a fixing device if an abnormality is detected, so that by relating the operation of this cut-off function and the operation of inhibiting at least one output at the power supply section to each other, these operations may be more easily controlled and also the number of components required can be reached.

Description:
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&#39;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&#39;s for turning the respective FET&#39;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 own duty ratio, thus stabilizing power supply. 
     In such a sleep state, the voltage Vcc 1  becomes about 6V. At the same time, the voltage Vcc 2  generated by a diode  116  and a capacitor  120  may be about 0.8V but actually becomes 3.2V because of a 3.2V power supply applied via the three-terminal regulator  150  and the diode  151 . 
     (Steady state) 
     The following will describe operations in the steady state. 
     To enter a printing state, the engine controller  200  sets the VCHG port High to turn ON the transistor  153  in order to conduct the resistor  152 , thus immediately returning the voltage Vcc 1  value to 24V. At the same time, it sets the RLDR port High to turn ON the transistor  301 , thus closing the relay  300 . 
     Then, at predetermined timing, the engine controller  200  drives the printer engine and controls the engine itself and a quantity of electrification to the heater, thus permitting printing. 
     The engine controller  200 , however, must be provided with the three ports of RLDR, FCHG, and VCHG, so that it needs to have circuits corresponding to these ports. 
     This leads to increases in the number of engine controller ports for power supply control in the sleep state and the number of the circuit components, accompanied by various problems of an enlarged apparatus size and an increased cost due to increases in the packaging surface area. 
     SUMMARY OF THE INVENTION 
     In view of the above, it is an object of the present invention to provide an image processing apparatus, an image recording apparatus, a method for controlling the same, and a power supply apparatus used in the same which can save on power dissipation in the wait state while reducing the number of parts required, the packaging surface area, and the apparatus size. 
     It is another object of the present invention to provide an inexpensive and small-sized image processing apparatus, image recording apparatus, and power supply apparatus used therein by decreasing the number of ports of the engine controller and the number of its components. 
     An image recording apparatus related to the present invention comprises: image recording controlling means for controlling image recording operations; a multiple-output power supply having plural converters for generating a driving voltage for image recording from an external power supply; and cutting-off means for cutting off supplying power from the above-described external power supply, wherein according to a cutting-off signal sent from the above-described image recording controlling means, the operating power for at least one of the above-described converters is cut off by the above-described cutting-off means. 
     Another image recording apparatus related to the present invention comprises: image recording controlling means for controlling image recording operations; a multiple-output power supply having plural converters for generating a driving voltage for image recording from an external power supply; and cutting-off means for cutting off supplying of power from the above-described external power supply, wherein according to a cutting-off signal sent from the above-described image recording controlling means, at least one of the above-described converters is stopped in operation by the above-described cutting-off means. 
     An image recording apparatus controlling method related to the present invention controls still another image recording apparatus related to the present invention comprising: image recording controlling means for controlling image recording operations; a multiple-output power supply having plural converters for generating a driving voltage for image recording from an external power supply; and cutting-off means for cutting off supplying of power from the above-described external power supply, wherein according to a cutting-off signal sent from the above-described image recording controlling means, operating power for at least one of the above-described converters is cut off by the above-described cutting-off means. 
     In the above-described image recording apparatus, preferably, operating power for the converter which feeds a driving voltage to the fixing device is cut off by the above-described cutting-off means. 
     Another embodiment of the present invention is directed to an image recording apparatus controlling method for controlling still another image recording apparatus comprising: image recording controlling means for controlling image recording operations; a multiple-output power supply having plural converters for generating a driving voltage for image recording from an external power supply; and cutting-off means for cutting off supplying of power from the above-described external power supply, wherein according to a cutting-off signal sent from the above-described image recording means, at least one of the above-described converters is stopped in operation by the above-described cutting-off means. 
     In the above-described image recording apparatus, preferably, operating power for the converter that feeds a driving voltage to the fixing device is cut off by the above-described cutting-off means. 
     The present invention provides an advantage of reducing a power loss in the wait state as well as a packaging surface area to decrease the apparatus size and its cost. 
     A power supply apparatus according to the present invention changes the power of a driving power supply based on frequency control. The apparatus includes power supply controlling means for controlling, in response to a change in the frequency, the power of the driving power supply generated by an external power supply; image processing controlling means for controlling an image processing apparatus to which power of the above-described driving power supply is supplied; and driving controlling means for changing the frequency of the above-described power supply controlling means according to a cutting-off controlling signal for cutting off the power supply which is output from the above-described image processing controlling means to the above-described image processing apparatus. 
     In this case, the above-described driving controlling means may change the above-described frequency of the above-described power supply controlling in a blocking manner. 
     The above-described driving controlling means may involve a wait operation whereby the above-described frequency is changed in a blocking manner and a steady operation whereby the above-described frequency is changed continuously. 
     The above-described driving controlling means may change the power supply voltage of the above-described driving power supply. 
     An image processing apparatus according to the present invention is supplied with power based on frequency control, and comprises the above-described power supply apparatus and image processing means for processing images using power with a controlled frequency fed out from that power supply apparatus. 
     The above-described image processing means may image recording means for recording images. 
     The above-described cutting-off controlling signal output from the above-described power supply apparatus can be output to fixing means of the above-described image recording means. 
     A method of power supply control according to the present invention actually changes the power of the driving power supply, and comprises the steps of: controlling the power of the driving power supply generated from the external power supply corresponding to a change in the frequency; controlling the image processing apparatus to which the power of the above-described driving power is supplied; and controlling the power supplied to the above-described driving power supply, by changing the above-described frequency. 
     A method for processing images according to the present invention actually processes images by supplying frequency-controlled power, and comprises the steps of: using the above-described power supply controlling method to output power which is changed according to frequency control; and processing images according to the output power. 
     According to the present invention, a power-supply cutting-off signal output from, for example the engine controller to a printer acts also as the frequency controlling signal, to change the frequency of the power supply control IC in order to vary a voltage value of the driving power supply, so that the cost due to an energy loss in the wait state can be reduced. Also, because the number of the ports of the engine controller can be reduced, the packaging surface area for the power supply apparatus can also be reduced to make the apparatus more compact. 
     According to the present invention, moreover, when the cutting-off means for cutting off the supply of power fed from an external power supply to a load is in a cut-off state, at least one of the outputs of a multiple-output power supply is inhibited. Therefore, by interrelating the controlling of the above-described load and the controlling for inhibiting the above-described at least one output of the power supply other than that load, the apparatus can be simplified in terms of configuration and control. 
     Other objects and features of the present invention will become apparent from the following detailed description and the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a circuit diagram showing a configuration of a power supply system of a general electrophotographic type of an image recording apparatus; 
     FIG. 2 is a circuit diagram showing a configuration example of a power supply apparatus equipped to a printer; 
     FIG. 3 is a timing chart explaining operation timing in a sleep state and a steady state of the power supply apparatus of FIG. 2; 
     FIG. 4 is a circuit diagram showing a configuration of a first embodiment of the present invention; 
     FIG. 5 is a circuit diagram showing a configuration of a second embodiment of the present invention; 
     FIG. 6 is a circuit diagram showing a configuration of a third embodiment of the present invention; 
     FIG. 7 is a circuit diagram showing a configuration of a power supply apparatus equipped to a printer according to a fourth embodiment of the present invention; 
     FIG. 8 is a timing chart explaining operation timing in a sleep state and a steady state of the power supply apparatus of FIG. 7; and 
     FIG. 9 is a circuit diagram showing a configuration of a power supply apparatus equipped to a printer according to a fifth embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following will describe embodiments of the present invention with reference to the accompanying drawings. 
     First Embodiment 
     FIG. 4 is a circuit diagram showing a configuration of a power supply circuit of an image recording apparatus according to a first embodiment of the present invention, in which the same reference numerals indicate the same components over FIGS. 1 and 4. 
     In the circuit of FIG. 4, the contact of the relay  300 , which provides a power supply cutting-off means, is disposed on the AC power supply input line between the commercial AC power supply  1  and the diode bridge  2 , in such a configuration that through itself, driving power is supplied from the triac  500  to the heating means (heater)  400  of a fixing device. To the lower-stage converter is supplied not through the relay  300  a direct current rectified at a diode bridge  102  and smoothed at a capacitor  103 . The other configurations are the same as those of FIG. 1, so that their description is omitted here. 
     The apparatus of the above-described configuration comprises: a multiple-output power supply having plural (two in this case) converters for generating a driving voltage (AC voltage) used in recording of images from the commercial power supply  1 , which is an external power supply; and the relay  300  as a means for cutting off the supply of power from the commercial AC power supply. In such a configuration, according to a cutting-off signal sent from the engine controller, which is an image recording controlling means for controlling image recording operations, supply of operating power is cut off by the above-described relay  300  to at least one of those converters. In this embodiment, the cutting-off signal sent from the engine controller turns ON the transistor  601  to activate the relay  300 , in order to cut off power supply only to the upper-stage converter, thus stopping the converter operations. 
     Note here that in contrast to the circuit configuration of FIG. 1 where the relay  600  is independently provided for cutting off the 24V power supply, in this embodiment, the relay  300  for cutting off a driving voltage to the heating means of the fixing device is used also for that purpose. 
     With this, it is possible to suppress a power loss in the wait state and also reduce the number of the components and the packaging surface area, thus decreasing the apparatus size and the cost. 
     Furthermore, in this embodiment, wherein the engine controller  200  makes switchover to the energy-saving mode, in a constant lapse of time after the image recording apparatus enters the wait state, the relay  300  is opened to cut off power supply to the 24V power supply from the AC power supply  1 . 
     In this embodiment, the relay  300  does not use as its power supply a 24V one but a 3.3V one or any other controlling power supply the voltage of which does not drop in the stand-by state, so that the apparatus may be restored from the energy-saving mode by the engine controller  200  when it closes the relay  300 . 
     Thus, as compared to the circuit configuration example shown in FIG. 1, although the diode bridge  102  and the smoothing capacitor  103  are added to the 3.3V power supply, there is no need to provide a relay and a transistor for driving that relay, thus enabling reduction of the cost and the packaging surface area. 
     Furthermore, although in this embodiment has been described a method of using a relay to cut off a driving voltage for the heating means  400  of the image recording apparatus, any other means for cutting off the AC power supply  1  may also be used. 
     Second Embodiment 
     FIG. 5 is a circuit diagram showing a second embodiment of the present invention, wherein the same reference numbers indicate the same components. 
     The driving circuit of the upper-stage converter in this embodiment comprises a power-supply controlling IC provided with an ON/OFF function, so that when its ON/OFF terminal is at the H level (higher than a constant voltage), the power-supply controlling IC is activated. When the ON/OFF terminal is at the L level (lower than the constant voltage), on the other hand, the power-supply controlling IC is deactivated. 
     In the above-described circuit, when printing, the engine controller closes the relay  300 . In this case, the ON/OFF terminal of the power-supply controlling IC of the driving circuit  4  is set at the H level through the AC power supply  1 , a resistor  310 , a diode  311 , a resistor  312 , and a capacitor  313 , thus starting the operations of the 24V power supply converter. Furthermore, in a certain lapse of time since the stand-by point in time, the engine controller  200  opens the relay  300 . In this state, the ON/OFF terminal of the power-supply controlling IC of the driving circuit  4  is set at the L level, thus stopping the operations of the 24V power supply converter. Therefore, such a configuration has the same effects as the first embodiment. 
     Third Embodiment 
     FIG. 6 is a circuit diagram showing a third embodiment of the present invention, wherein the same reference numbers indicate the same components. Although in the above-described second embodiment, there has been explained such a case that the driving circuit  4  of the upper-stage converter comprises the power-supply controlling IC provided with the ON/OFF function, such a configuration that is show in FIG. 6 may be used not to supply power to the driving circuit  4 . That is, by supplying a base current from the commercial power supply  1  through the relay  300 , the resistor  310 , and the diode  311  to a transistor  314 , an operating voltage is supplied to the driving circuit  4  from the upper-stage converter. Such a configuration has the same effects as the second embodiment. 
     Although in the second and third embodiments, there has been explained such a configuration that the relay for cutting off the driving voltage for the heating means  400  of the image recording apparatus is turned ON/OFF to cut off the 24V power supply, any other configuration may be employed such that the 24V power supply can be cut off by a switching means such as a relay for cutting off the AC power supply when it is turned ON/OFF. 
     In this embodiment, the relay  300  does not use as its power supply a 24V one but a 3.3V one or any other controlling power supply (of a voltage not dropped in a stand-by state), so that the apparatus may be restored from the energy-saving mode when the engine controller  200  closes the relay  300 . 
     Thus, as compared to the circuit configuration example of FIG. 1, although the diode  102  and the smoothing capacitor  103  are added to the 3.3V power supply, there is no need to provide a relay and a transistor for driving the relay, thus enabling reduction of the cost and the packaging surface area. 
     Furthermore, although in this embodiment, there has been explained an embodiment of realizing a function of cutting off the 24V power supply by using a relay for cutting off the driving voltage for the heating means  400  of the image recording apparatus, any other means may be used for cutting off the AC power supply  1  or, the relay  300  may use as its power supply, in place of a 24V one, a 3.3V one or any other controlling power supply (of a voltage not dropped in the stand-by state). 
     The following will describe embodiments of an apparatus which comprises power supply controlling means for controlling a voltage of a driving power supply (DC power supply) generated from the commercial power supply corresponding to a change in frequency and image recording controlling means for controlling the recording operations by the image recording apparatus, wherein based on a signal output from the image recording controlling means to the image recording apparatus, e.g. a cutting-off signal for cutting off the power supply, the frequency of the power supply controlling means is changed to vary the voltage value of the driving power supply. 
     Fourth Embodiment 
     A fourth embodiment is described with reference to FIGS. 7 and 8. The same components are indicated by the same reference numerals in FIGS. 1,  7  and  8 , so that their description is omitted here. 
     FIG. 7 shows a circuit configuration of a power-supplying power supply built in a printer, an image processing apparatus related to the present invention. 
     (Basic configuration) 
     First, the basic configuration of this apparatus is described. 
     A reference numeral  1  indicates an AC power supply, an AC voltage of which is full-wave rectified at the diode bridge  2  and smoothed at the smoothing capacitor  3 . 
     A reference numeral  4  indicates a power-supply controlling IC and is activated by power-supply controlling IC staring resistors  5  and  6 . 
     After power application, the power supply controlling IC  4  turns ON/OFF an FET  7 . When the FET  7  is ON, a voltage is applied to a main winding  27  and a transformer accumulates power therein. 
     When the power supply is turned OFF, energy accumulated at the transformer is released to an auxiliary winding  29 , a secondary winding  28 , and a winding  128 . 
     Energy released from the auxiliary winding  29  is smoothed at the diode  9  and the capacitor  8 , thus providing an auxiliary power supply for the power supply controlling IC  4  after power application. 
     Energy released from the secondary winding  28  is smoothed by the diode  16  and the capacitor  20 . 
     A reference numeral  24  indicates a shunt regulator and flows a current from the cathode to the anode so that a value obtained by dividing the voltage Vcc 1  by the feedback resistors  21  and  22 , the resistor  152 , and the transistor  153  may be equal to the reference voltage Vref of the shunt regulator  24 . A reference numeral indicates a power supply controlling resistor. 
     A reference numeral  12  indicates a photo-coupler. When a current flows through the light emitting sections  12   a  of the photo-coupler  12 , the light receiving section  12   b  in turned ON, thus permitting a current to flow out of the F.B section of the power supply controlling IC  4 . 
     According to this current, the power supply controlling IC  4  controls a duty ratio, thus stabilizing the power supply. 
     A reference numeral  150  indicates a three-terminal regulator, to which generally the voltage Vcc 1  (24V) is applied and is then converted to a voltage of Vcc 2 +0.6V (3.9V) approximately. Then, it is applied through the diode  151  to the power supply Vcc 2  (3.3V). 
     In the steady state, voltage output from the regulator  150  is designed to be Vcc 2 −0.1V (3.2V), lower than the voltage Vcc 2  (3.3V) generated by the diode  116  and the capacitor  120 . The reason for this is to prevent a regulator loss by flowing no current from the regulator in the steady state. 
     A reference numeral  300  indicates a relay and acts as a breaker which prevents an AC voltage from being applied to the heater  400  if the heater  400  or the heater driving circuit  500  fails. 
     The heater  400  is a means for fixing toner transferred onto paper in the electrophotographing process and used to constitute a fixing device for a printer. The heater driving circuit  500  is used to energize the fixing device. 
     (Configuration of main part) 
     A reference numeral  200  indicates the engine controller. This engine controller  200  has two ports of the RLDR port and the VCH port. 
     The following will describe the configuration of the main part related to the present invention. to which the corresponding control circuits are connected respectively. 
     In this configuration, at the power supply controlling IC  4 , which is the control circuit for the RLDR port, a contact point P between the FCHG port and the GND port is connected via the resistor r 1  and a diode D to a point Q on one end side of the relay  300 . 
     The engine controller  200  drives the printer engine, controls the engine and the heater driving circuit  500  for controlling a quantity of electrification to the heater  400  and the relay  300 , and also controls frequency conversion for the power supply controlling IC  4 . 
     That is, the engine controller  200  sets the RLDR port High/Low to turn the transistor  301  ON/OFF in order to open and close the relay  300  and, at the same time, changes a voltage level at the point Q to turn the diode ON/OFF in order to change a voltage level at the point P, thus controlling frequency conversion for the power supply controlling IC  4  in the sleep state. 
     Thus, this embodiment features a respect that the signal for frequency conversion for the power supply controlling IC  4  in the sleep state acts also as the cutting-off signal for operating the cutting-off relay  300  on the side of the heater  400 . 
     (Circuit operations) 
     The following will describe the circuit operations n of this apparatus. 
     In this embodiment, the engine controller  200  conducts various control operations in the sleep and wait states. 
     (Sleep state) 
     The following will describe the operations in the sleep state. 
     When the engine controller  200  switches to the sleep mode, the printer enters the wait state and, in a certain lapse of time, the RLDR port is set Low. 
     With this, the transistor  301  is turned OFF and the relay  300  is opened and the FCHG port of the power supply controlling IC  4  is set Low. As a result, as shown in FIG. 8, as compared to the steady state, in the sleep state, the frequency of the power supply controlling IC  4  is decreased. Since the power supply controlling IC  4  is in such an aspect that some pulses are removed from a pulse string output in a Low state as compared to a pulse string output in a High state by the FCHG port, it is called a blocking operation in this specification. Even aside from such an aspect, however, the present invention can be embodied as far as the frequency output in a Low state is lower than that output in a High state by the FCHG port. Furthermore, even when the frequency output in a High state is equal to that output in a Low state by the FCHG port, a pulse string may be output in a Low state in a blocking manner. 
     Also at the same time, the engine controller  200  sets the VCHG port at Low, turns the transistor  153  OFF, and makes the resistor  152  nonconductive, to set the voltage Vcc 1  at 6V. 
     (Steady state) 
     The following will describe the circuit operations for printing in the steady state. 
     For printing, the engine controller  200  sets the VCHG port High, turns the transistor  153  ON, and makes the resistor  152  conductive, to set the voltage Vcc 1  at 24V. 
     Then, the engine controller  200  sets the RLDR port High, turns the transistor  301  ON, and closes the relay  300 . With this, the diode D is turned ON to raise the voltage level at the point P, thus setting the FCHG port of the power supply controlling IC  4  High. As a result, as shown in FIG. 2, the frequency of the power supply controlling IC  4  is decreased as compared to that in the sleep state. 
     As described above, since this embodiment, in contrast to the prior-art examples, has no FCHG port or separate controlling circuits (photo-coupler  112  etc.) connected to that port, it is possible to reduce the number of photo-couplers and ports of the engine controller  200 , thus reducing the cost and the packaging surface area. 
     Fifth Embodiment 
     The following will describe a fifth embodiment of the present invention with reference to FIG.  9 . The same components as those in FIG. 4 are indicated by the same reference numerals and so their description is omitted here. 
     This embodiment features a respect that variations in the frequency and the voltage of the power supply controlling IC  4  are controlled by the same port. 
     The engine controller  200  is provided only one port, i.e. the RLDR port, to which various corresponding control circuits are connected. 
     In this configuration, to a contact point on the side of the RLDR port is connected the base of the transistor  153 . 
     With this, the engine controller  200  drives the printer engine, controls the engine, the heater driving circuit  500  for controlling a quantity of electrification to the heater  400 , the relay  300 , and frequency conversion for the power supply controlling IC  4  described above in the fourth embodiment, and also controls the driving voltage. 
     (Sleep state) 
     The following will describe the operations in the sleep state. 
     When the engine controller  200  switches to the sleep mode, the printer enters the wait state and, in a certain lapse of time, the RLDR port is set Low. 
     With this, the transistor  301  is turned OFF and the relay  300  is opened, so that the FCHG port of the power supply controlling IC  4  is set Low, so that as described above with reference to FIG. 8, the frequency of the power supply controlling IC  4  is decreased. 
     Furthermore, at the same time when the RLDR port is set Low, the transistor  153  is turned OFF and the resistor  512  is made nonconductive, to set the voltage Vcc 1  at 6V. 
     (Steady state) 
     The following will describe the circuit operations of printing in the steady state. 
     For printing, the engine controller  200  sets the RLDR port High, turns the transistor  513  ON, and makes the resistor  152  conductive, to set the voltage Vcc 1  at 24V. 
     Furthermore, at the same time, the transistor  301  is turned ON and the relay  300  is closed. With this, the FCHG port of the power supply controlling IC  4  is set High, so that the frequency of the power supply controlling IC  4  is increased. 
     Although in this embodiment, the port for controlling variations in the driving voltage is supposed to be the relay  300 , it is not limited to that but any other port such as a fan may be used to have the same effects. 
     Furthermore, although in the fourth and fifth embodiments such an example has been explained that the conversion signal for controlling the frequency of the power supply controlling IC  4  is used also as the cutting-off signal for the heater  400  in the printer, any other control signal, for example a signal for cutting off the AC power supply  1 , may also be used for that purpose. 
     Although in the above-described embodiments a flyback type multiple-output power supply has been explained, any other type may provide almost the same control such as a forward power supply, a resonant power supply, a series dropper, or a ringing chalk converter. 
     Furthermore, in this embodiment, the relay  300 , etc. are controlled in operation according to instructions sent from the ports of the engine controller  200  in the printer, and an external host computer connected to the printer may send such instructions. 
     Moreover, the present invention may be applicable to a system comprising plural apparatuses (e.g., host computer, interface devices, reader, printer, etc.) or a single apparatus (e.g., copy machine, facsimile, etc.). 
     In addition, the present invention can of course be achieved by supplying a program to the system or the apparatus. Furthermore, the effects of the present invention can be enjoyed by supplying a memory medium storing programs represented by the software for achieving the present invention, to a system or an apparatus so that its computer (i.e., CPU or MPU) may read out the program code stored in that memory medium and then execute it. 
     In this case, the program code itself read out from the memory medium achieves the functions of the above-described embodiments, so that the memory medium storing that program code achieves the present invention. 
     The memory medium storing the program code comes in, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, or a ROM (mask ROM, flash EEPROM, etc.). 
     Furthermore, such a case is of course included in the present invention that by executing the program code read out by the computer, not only the functions of the above-described embodiments are achieved but also the OS (Operating System) running in the computer can execute part or all of the actual processing according to the instructions of that program code, thus achieving those functions of the above-described embodiments. 
     Moreover, such a case is of course included in the present invention that the program code read out from the memory medium is written into a memory equipped to a function-expansion board inserted into the computer or a function-expansion unit connected to the computer, so that according to the instruction of that program code, the CPU of that function-expansion board or the function-expansion unit may execute part or all of the actual processing, thus achieving the functions of the above-described embodiments.