JP3598852B2 - Power supply for electronic equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a power supply device for an electronic device, and more particularly to a power supply device that enables an electronic device to repeat two modes of an operating state and a stopped state when there is no load or light load. In this specification, the term “no load” refers to a state in which the power supply device is turned on, but the power supply device does not require power. The light load refers to a case where the output side device does not require a constant voltage. For example, in a printer, it means a state where the print head is stopped.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a power supply device for an electronic device includes a transformer having a commercial power supply as a primary side and a drive unit or the like of the electronic device as a secondary side, and an AC generating switching disposed on the primary side of the transformer. A switching power supply having a transistor is generally used (see Japanese Patent Application Laid-Open Nos. Hei 5-137331, Hei 6-165489, and Hei 8-300775).
[0003]
For example, when such a power supply device is used as a stabilized power supply in a power supply unit of a printer, the power supply to the printer control unit and the printer mechanism unit is adjusted by controlling the switching operation of the AC generation switching transistor. In a printer using a power supply device of this type, when power supply to the printer control unit and the printer mechanism unit is stopped, for example, a light emitting element disposed on the secondary side of the transformer and a light receiving element disposed on the primary side A light control signal from a light emitting element on the secondary side is received by a light receiving element on the primary side, and based on the signal output from the light receiving element on the primary side, the switching transistor for AC generation is used. Is set to a non-switching state (see the above-mentioned Japanese Patent Application Laid-Open No. 8-300775).
[0004]
Recently, as one of such switching power supplies, a ringing choke converter (hereinafter referred to as RCC) circuit type is often used in power supplies for electronic devices such as printers because of the advantage that the number of components of the power supply is small. Have been.
[0005]
FIG. 9 is a circuit diagram of a constant voltage control detection circuit portion of a general RCC type power supply device. In the circuit configuration of FIG. 9, when the Zener voltage of the Zener diode ZD1 in the figure is exceeded, the control signal S1 which is a signal for suppressing the switching operation is output from the photodiode PD1 constituting the light emitting element on the secondary side of the photocoupler. Is received by the phototransistor PT1 that constitutes the light receiving element on the primary side of the photocoupler described above, and the primary side control circuit controls the switching transistor for AC generation so that the output voltage is stably maintained. I have.
[0006]
FIG. 10 is a schematic diagram showing the time change of the output voltage of the circuit of FIG. 9, and the voltage of the output (terminal) 1 shown in FIG. 9 is stably kept almost constant. FIG. 11 is a diagram generally explaining the breakdown of the power loss of the power supply device. The power loss includes a substantially constant amount of loss regardless of the magnitude of the output power (see FIG. 11B) and a loss proportional to the output power [see FIG. 11C]. As is clear from the above, the ratio of the fixed amount of loss increases as the output power decreases at light load.
[0007]
[Problems to be solved by the invention]
For example, when a switching power supply whose output power varies widely is used for an electronic device whose output power differs depending on the state of the electronic device (for example, an operation state and a standby state), when the output power is large as in the operation state, Although the power conversion efficiency is improved, the driving capacity becomes excessive at a light load such as a standby state, and the power conversion efficiency is reduced. This is because, as shown in FIGS. 11 (a), (b) and (c), the loss of the power supply device shows a loss that shows a substantially constant amount regardless of the magnitude of the output power, and a loss proportional to the output power. This is because the ratio of a certain amount of loss increases as the output power decreases at light load. In particular, in the above-described RCC power supply device, as shown in FIG. 12B, at no load or light load, Vce of the primary side switching transistor cannot be sufficiently reduced even during the ON period, so that power loss of the transistor is reduced. There was a problem of increasing.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to provide a power supply device for an electronic device that can obtain the same output power as a conventional one in a no-load or light-load state, and can greatly reduce the loss compared to the conventional one. .
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, at the time of no load or light load, the power supply device repeats two modes of an operating state and a stopped state. Thereby, power loss at the time of no load or light load can be significantly reduced. In particular, in a power supply device employing the RCC method, for example, an intermittent operation mode in which a maximum output operation with good circuit efficiency and a stop state with extremely small loss are repeatedly switched to operate is adopted. As a result, in the RCC power supply device, the average output power is equivalent to a light load, but the loss can be significantly reduced. However, the output voltage tends to increase in the operating state and tends to decrease in the stopped state, so that the output voltage is controlled substantially within the allowable range of the output voltage.
[0010]
That is,The present invention is a power supply device for an electronic device capable of taking an intermittent operation mode in which the electronic device is in an unloaded or lightly loaded state while the power of the electronic device is turned on, and repeats an operation state and a stop state, An output voltage control circuit for controlling an output voltage, input means for inputting a switching signal generated in accordance with the output voltage, and switching means for switching operation and stop of the output voltage control circuit in accordance with the switching signal Wherein the output voltage control circuit controls the output voltage when the switching unit is activated.It is characterized by the following.
[0011]
Also,The output voltage control circuit performs a maximum operation when the operation state is set by the switching unit.It is characterized by the following.
[0012]
Further, in the power supply device for an electronic device employing a ringing choke converter circuit system, the operation state is an optimum operation state in which the efficiency of the ringing choke converter circuit is high, and the intermittent operation mode is the optimum operation state and the loss. An extremely small stop state is repeatedly switched and operated by the pulse-like switching signal.It is characterized by the following.
[0013]
Also,In the present invention, the optimum operation state is a maximum output operation state. Here, the switching signal may be switched at predetermined time intervals after the output voltage reaches the maximum output. Further, the switching signal may be switched when the output voltage reaches a maximum output. Further, the switching signal may be switched before the output voltage reaches a maximum output.
[0014]
Further, in the present invention, the operating state and the stop state are repeated by arbitrarily raising and lowering the detected voltage of the constant voltage detection signal between a first voltage and a second voltage lower than the first voltage. Take intermittent operation modeIt is characterized by the following.
[0015]
A first predetermined time is required for the output voltage of the output voltage control circuit to rise from the second voltage to the first voltage by the switching means, and the output of the output voltage control circuit is output by the switching means. When a second predetermined time is required for the voltage to decrease from the first voltage to the second voltage, the time during which the switching signal is at a low level is longer than the first predetermined time, and the switching signal is at a high level. May be longer than the second predetermined time. Further, it takes a first predetermined time for the output voltage of the output voltage control circuit to rise from the second voltage to the first voltage by the switching means, and the output of the output voltage control circuit is output by the switching means. When it takes a second predetermined time for the voltage to fall from the first voltage to the second voltage, the time during which the switching signal is at a low level is equal to the first predetermined time, and the switching signal is at a high level. May be equal to the second predetermined time. Further, it takes a first predetermined time for the output voltage of the output voltage control circuit to rise from the second voltage to the first voltage by the switching means, and the output of the output voltage control circuit is output by the switching means. When it takes a second predetermined time for the voltage to decrease from the first voltage to the second voltage, the time during which the switching signal is at a low level is shorter than the first predetermined time, and the switching signal is at a high level. May be shorter than the second predetermined time.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, a first embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the power supply device for an electronic device of the present invention is applied to an example in which the power supply unit is used as a stabilized power supply in a power supply unit of an inkjet printer. FIG. 1 shows an excerpt of a constant voltage control detection circuit section which is a main part of the power supply device of the present embodiment. The power supply device of the present embodiment is also of a general RCC type, and its basic configuration is the same as that of a known device, and is not different from that described in the conventional example.
[0017]
That is, as shown in FIG. 1, the power supply device for a printer according to the present embodiment uses a commercial power supply [AC] (not shown) as a primary side and a printer driver (not shown) as a secondary side. It has a transformer 43 and an AC generation switching transistor Q44 arranged on the primary side of the transformer 43. This power supply device includes a control signal photocoupler Pc. The control signal photocoupler Pc includes a photodiode PD1 as a light emitting element disposed on the secondary side of the transformer 43 and a light receiving element disposed on the primary side. As a phototransistor PT1. Then, the control signal S1 from the photodiode PD1 on the secondary side is received by the phototransistor PT1 on the primary side, and this phototransistor PT1 conducts, so that the primary side control circuit CC switches the switching transistor Q44 for AC generation. Set to non-switching state. When the voltage exceeds the Zener voltage (42 V) of the Zener diode ZD1 in the figure, the control signal S1 which is a signal for suppressing the switching operation is generated from the photodiode PD1 on the secondary side of the control signal photocoupler Pc. The primary-side phototransistor PT1 receives light, and the primary-side control circuit CC controls the AC generation switching transistor Q44 to stably maintain the output voltage.
[0018]
The difference between the constant voltage control detection circuit section of this embodiment and the conventional example shown in FIG. 9 is that a stop signal photocoupler Ps and a switching transistor Q1 are added to the circuit configuration of FIG. The feature of the present embodiment is that the power supply device is switched by the stop signal S2 separately from the control signal S1 in order to cause the power supply device to repeat the above-described two modes of the operation state and the stop state or to take the intermittent operation mode. The point is that the operation is arbitrarily stopped.
[0019]
That is, the constant voltage control detection circuit section includes the stop signal photocoupler Ps and the switching transistor Q1 in addition to the above-described configuration. The stop signal photocoupler Ps includes a photodiode PD2 as a light emitting element arranged on the secondary side of the transformer 43 and a phototransistor PT2 as a light receiving element arranged on the primary side. Then, the stop signal S2 from the photodiode PD2 on the secondary side is received by the phototransistor PT2 on the primary side, and when this phototransistor PT2 is turned on, the primary-side control circuit CC turns on the switching transistor Q44 for AC generation. Stop the switching operation. The switching transistor Q1 is formed of a bipolar transistor with a common emitter, and its collector is connected to the cathode of the photodiode PD2 via a resistor, and its base is connected to the input terminal Tmi of the switching signal. A pulse of the switching signal is input to the input terminal Tmi.
[0020]
Now, the operation of the constant voltage control detection circuit will be described. In the circuit configuration of FIG. 1, when the switching signal Sc input to the input terminal Tmi is "L", the switching transistor Q1 is in the cut-off state, and the stop signal The photodiode PD2 of the photocoupler Ps does not emit the stop signal S2, and the output voltage of the power supply device appearing at the output (terminal) 1 is determined by the Zener voltage of the Zener diode ZD1. In the present embodiment, a ZD1 having a zener voltage of 42 V is selected in consideration of the voltage applied to the print head of the ink jet printer. Therefore, when the switching signal Sc is "L", the output set voltage is set to 42 V, and the voltage is stably supplied to the output (terminal) 1. Therefore, in the operation state of the printer, the output is set to the printer mechanism such as the print head. A constant voltage of 42V is supplied. On the other hand, when the switching signal Sc is "H", the switching transistor Q1 becomes conductive and a stop signal S2 is issued from the photodiode PD2 of the stop signal photocoupler Ps, and the stop signal S2 is transmitted to the primary side phototransistor PT2. Light is received, and the phototransistor PT2 becomes conductive, so that the primary side control circuit CC stops the switching operation of the AC generation switching transistor Q44.
[0021]
FIG. 2 is a schematic diagram showing the time change of the output voltage of the circuit of FIG. 1. The time change of the voltage of the output (terminal) 1 repeats rising and falling in accordance with “L” and “H” of the switching signal. Is shown. FIG. 2 shows the following three examples of the switching method. As shown in FIG. 2, the switching method 1 is a control example in which the switching signal switches from “L” to “H” shortly after the output voltage reaches 42V. The switching method 2 is a control example in which the switching signal switches from “L” to “H” when the output voltage reaches 42V. The switching method 3 is a control example in which the switching signal switches from “L” to “H” before the output voltage reaches 42V.
[0022]
As described above, the switching method 1 represents a control example in which the switching signal switches from “L” to “H” shortly after the output voltage reaches 42V. That is, as shown in FIG. 2, when the switching signal changes from “L” to “H” in period 1 and the switching signal changes from “L” to “H”, the stop signal S2 is generated from the photodiode PD2 of the stop signal photocoupler Ps, and the stop signal is output. S2 is received by the primary-side phototransistor PT2, and when the phototransistor PT2 is turned on, the primary-side control circuit CC stops the switching operation of the AC generation switching transistor Q44. The time change of the output voltage at this time decreases with time with a characteristic determined by the impedance connected to the load and the capacitance of the capacitor on the output side.
[0023]
When a certain period of time elapses and the switching signal changes from “H” to “L” in the period 2, the stop signal S 2 from the photodiode PD 2 of the stop signal photocoupler Ps is not issued. At this time, the output voltage becomes an undervoltage state lower than the output voltage set value of 42 V, the control signal S1 for suppressing the switching operation is not issued, and the primary side control circuit CC sends the maximum value to the AC generation switching transistor Q44. Perform switching operation. The temporal change of the output voltage at this time increases with time with a characteristic determined by the impedance connected to the load, the capacitance of the capacitor on the output side, and the current limit value of the switching element. When the output voltage reaches the output voltage set value of 42 V, the primary side control circuit CC shifts to a switching operation in a light load state. This is period 3.
[0024]
FIG. 3 is a diagram similar to FIG. 11A and illustrates the relationship between the power loss of the power supply device and the output power in the case of the switching methods 1, 2, and 3. As described with reference to FIG. 11A, the relationship between the power loss of the power supply device and the output power indicates a characteristic line that reaches point B from point O in FIG. Here, the point O is the operating point at stop, the point A is the operating point at light load, the point B is the operating point at maximum operation, Pa is the output power at light load, Pb is the output power at maximum operation, It is.
[0025]
As in the present embodiment, the average power loss when the power supply device repeats only the two states of the stop state and the maximum operation state is on the straight line connecting the points O and B in FIG. The average power loss at the time of load Pa is point L in the figure. Point L is a point where the line segment OB is internally divided by the reciprocal ratio of the time ratio between the stop state and the maximum operation state. Furthermore, the average power loss when the three states including the stop state and the maximum operation state plus the light load state are repeated is calculated by dividing the line segment LA connecting the points L and A by the sum of the time between the stop state and the maximum operation state. The point M is internally divided by the reciprocal ratio of the ratio to the load state time. Here, assuming that the time ratio of periods 1 to 3 in FIG. 2 is 4: 1: 1 and is applied to FIG. 3, point L is a point which internally divides line segment OB into 1: 4, and point M Is a point that internally divides the line segment LA into 1: (4 + 1), and it is clear that the power loss M can be made smaller than the power loss A at a light load.
[0026]
The switching method 2 represents a control example in which the switching signal switches from “L” to “H” when the output voltage reaches 42V. This is equivalent to setting the period 3 = 0 in the switching method 1. Here, assuming that the time ratio of the periods 1 to 3 in FIG. 2 is 4: 1: 0 and is applied to FIG. 3, the point L is a point that internally divides the line segment OB into 1: 4, and the power loss L It is clear that the point can be made smaller than the light load point A at light load.
[0027]
The switching method 3 represents a control example in which the switching signal switches from “L” to “H” before the output voltage reaches 42V. When the switching signal changes from "L" to "H" in the period 4, a stop signal S2 is issued from the photodiode PD2 of the stop signal photocoupler Ps, and the primary side control circuit CC is switched to the AC generation switching transistor. The switching operation of Q44 is stopped. The time change of the output voltage at this time decreases with time with a characteristic determined by the impedance connected to the load and the capacitance of the capacitor on the output side.
[0028]
When a certain period of time elapses and the switching signal changes from "H" to "L" in the period 5, the stop signal S2 from the photodiode PD2 of the stop signal photocoupler Ps is not issued. At this time, the output voltage becomes an undervoltage state lower than the output voltage set value of 42 V, the control signal S1 for suppressing the switching operation is not issued, and the primary side control circuit performs the maximum switching operation. The temporal change of the output voltage at this time increases with time with a characteristic determined by the impedance connected to the load, the capacitance of the capacitor on the output side, and the current limit value of the switching element.
[0029]
If the switching signal changes from “L” to “H” before the output voltage reaches the output voltage set value of 42 V, a stop signal S2 is issued from the photodiode PD2 of the stop signal photocoupler Ps, and Is repeated. Here, assuming that the time ratio of the periods 4 and 5 in FIG. 2 is 4: 1 and is applied to FIG. 3, the point L is a point that internally divides the line segment OB into 1: 4, and the power loss L point is It is clear that the power loss at light load can be made smaller than the point A. Note that the switching signal may be generated using time as a parameter, or the output voltage may be detected and appropriately generated according to the voltage. It is easier to control if the output voltage is detected and generated appropriately according to the voltage. Further, the duration of the switching signal “L” and the duration of the “H” need not be constant.
[0030]
Next, a second embodiment of the present invention will be described with reference to FIGS. Also in this embodiment, the electronic apparatus power supply device of the invention is applied to an example in which the power supply unit is used as a stabilized power supply in a power supply unit of an inkjet printer.
[0031]
FIG. 4 shows an excerpt of a constant voltage control detection circuit section which is a main part of the power supply device according to the second embodiment of the present invention. The power supply device of the present embodiment is also of a general RCC system, and its basic configuration is the same as that of the known device, and is not different from the conventional example and the first embodiment. The same parts as those in the first embodiment are indicated by the same reference numerals.
[0032]
That is, as shown in FIG. 4, the printer power supply device of the present embodiment does not have the stop signal photocoupler as in the first embodiment, and uses a single Zener diode ZD1 in the conventional example. What is different is that a Zener diode ZD2 is connected in series with the Zener diode ZD1 to form a two-stage configuration. The collector and the emitter of the switching transistor Q1 'are connected to the anodes of the Zener diodes ZD1 and ZD2, respectively. The feature of this embodiment is that a power supply stop state is created by intentionally raising and lowering the constant voltage detection signal (control signal S1).
[0033]
The output setting voltage of the power supply device in the circuit configuration of FIG. 4 is the sum of the Zener voltages of the two-stage Zener diodes ZD1 and ZD2 because the switching transistor Q1 'is in the cut-off state when the switching signal is "L". "", The switching transistor Q1 'is conductive, so that ZD2 is bypassed and determined by the zener voltage of only ZD1. In the present embodiment, a ZD1 having a Zener voltage of 40 V and a ZD2 having a Zener voltage of 4 V are selected. Therefore, when the switching signal is "L", the output set voltage is set to 44V, and when the switching signal is "H", ZD2 is bypassed and set to 40V only for ZD1, and each voltage is stably supplied. . FIG. 5 is a schematic diagram showing the time change of the output voltage of the circuit of FIG. 4, and the voltage of the output (terminal) 1 changes repeatedly with rising and falling according to the switching signal “L” and “H”. Is shown. Here, the time required for the power supply device to perform the switching operation and the output voltage to rise from 40 V to 44 V is Tup, and the time required for the power supply device to stop the switching operation and the output voltage to fall from 44 V to 40 V is Tdown. Expressing this, Tup is determined by the impedance connected to the load, the capacitance of the output side capacitor, and the current limit value of the switching element, and Tdown is determined by the impedance connected to the load and the capacitance of the output side.
[0034]
FIG. 5 shows three examples of the following switching methods 4 to 6 as switching methods in the present embodiment, in contrast to the switching methods 1 to 3 in the first embodiment described above.
[0035]
The switching method 4 is a control example in which the time when the switching signal is “L” is longer than Tup, and the time when the switching signal is “H” is longer than Tdown. The switching method 5 is a control example in which the time when the switching signal is “L” is equal to Tup, and the time when the switching signal is “H” is equal to Tdown. The switching method 6 is a control example in which the time when the switching signal is “L” is shorter than Tup, and the time when the switching signal is “H” is shorter than Tdown. The switching method 4 represents a control example in which the time when the switching signal is “L” is longer than Tup, and the time when the switching signal is “H” is longer than Tdown.
[0036]
When the switching signal changes from “L” to “H” in the period 1 and the output setting voltage is accordingly reduced from 44 V to 40 V, the output voltage 44 V so far becomes the output voltage setting value. When the voltage exceeds the excessive voltage, the control signal S1 for suppressing the switching operation is issued to the primary side control circuit CC, and the primary side control circuit CC stops the switching operation. As described above, the time change of the output voltage at this time decreases with time according to the characteristic determined by the impedance connected to the load and the capacitance of the capacitor on the output side. When the output voltage reaches the output voltage set value of 40 V, the primary side control circuit CC resumes the switching operation in the light load state. This is period 2.
[0037]
When a certain period of time elapses and the switching signal changes from "H" to "L" in the period 3 and the switching set signal changes from "H" to "L", the output set voltage is raised from the previous 40V to 44V. Becomes an undervoltage state lower than the output voltage set value, the control signal S1 for suppressing the switching operation is not issued, and the primary side control circuit CC performs the maximum switching operation. As described above, the time change of the output voltage at this time increases with time with a characteristic determined by the impedance connected to the load, the capacitance of the output side capacitor, and the current limit value of the switching element. When the output voltage reaches the output voltage set value of 44 V, the primary side control circuit CC shifts to a switching operation in a light load state. This is period 4.
[0038]
Here, the relationship between the power supply device power loss and the output power in the case of the switching methods 4, 5, and 6, will be described with reference to FIG. 3 as in the first embodiment. First, the case of the switching method 4 will be described. Here, assuming that the time ratio of periods 1 to 4 in FIG. 5 is 4: 1: 1: 2 and is applied to FIG. 3, point L is a point that internally divides line segment OB into 1: 4. The point M is a point that internally divides the line segment LA into (1 + 2) :( 4 + 1), and it is clear that the power loss M can be made smaller than the power loss A at a light load.
[0039]
The switching method 5 represents a control example in which the time when the switching signal is “L” is equal to Tup, and the time when the switching signal is “H” is equal to Tdown. This is equivalent to setting the period 2 = 0 and the period 4 = 0 in the switching method 4. Here, assuming that the time ratio of the periods 1 to 4 in FIG. 5 is 4: 0: 1: 0 and is applied to FIG. 3, the point L is a point that internally divides the line segment OB into 1: 4, and Obviously, the loss L point can be made smaller than the light load power loss A point. Compared with the switching method 4, the average power loss is further reduced because there are no periods 2 and 4 at light load.
[0040]
The switching method 6 represents a control example in which the time when the switching signal is “L” is shorter than Tup, and the time when the switching signal is “H” is shorter than Tdown.
[0041]
When the switching signal changes from “L” to “H” in the period 5 and the output setting voltage is accordingly reduced from 44 V to 40 V, the output voltage Vhigh up to that time becomes the output voltage setting value. When the voltage exceeds the excessive voltage, a signal for suppressing the switching operation is issued to the primary side control circuit CC, and the primary side control circuit CC stops the switching operation. As described above, the time change of the output voltage at this time decreases with time according to the characteristic determined by the impedance connected to the load and the capacitance of the capacitor on the output side.
[0042]
Period 6 is reached before the output voltage reaches the output voltage set value of 40 V, and when the switching signal changes from “H” to “L”, the output set voltage is raised from the previous 40 V to 44 V accordingly. Therefore, the output voltage Vlow becomes an undervoltage state lower than the output voltage set value, the control signal S1 for suppressing the switching operation is not issued, and the primary side control circuit CC performs the maximum switching operation. As described above, the time change of the output voltage at this time increases with time with a characteristic determined by the impedance connected to the load, the capacitance of the output side capacitor, and the current limit value of the switching element. If the switching signal changes from “L” to “H” before the output voltage reaches the output voltage set value of 44 V, the output set voltage is accordingly reduced from 44 V to 40 V, and Repeat the operation.
[0043]
Now, the relationship between the power supply power loss and the output power in the case of the switching method 6 will be described. Here, assuming that the time ratio of periods 5 and 6 in FIG. 5 is 4: 1 and is applied to FIG. 3, point L is a point that internally divides line segment OB into 1: 4, and power loss L point is It is clear that the power loss at light load can be made smaller than the point A. As in the case of the switching method 5, the average power loss is further reduced as compared with the case of the switching method 4 because there are no periods 2 and 4 at the time of light load. In the switching methods 5 and 6, the switching signal may be generated using time as a parameter, or an output voltage may be detected and appropriately generated according to the voltage. It is easier to control if the output voltage is detected and generated appropriately according to the voltage. Further, the duration of the switching signal “L” and the duration of the “H” need not be constant.
[0044]
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 6 shows an excerpt of a constant voltage control detection circuit section which is a main part of the power supply device according to the third embodiment of the present invention. The power supply device of the present embodiment is also of a general RCC type, and its basic configuration is not different from those described in the conventional example and the first and second embodiments. Parts similar to those of the first and second embodiments are denoted by the same reference numerals.
[0045]
That is, the printer power supply device of the present embodiment can be said to be a modification of the above-described second embodiment, and as shown in FIG. It does not have a coupler, and controls the switching operation of the switching transistor Q44 for AC generation by blinking the control signal photocoupler with the switching signal.
[0046]
That is, in the present embodiment, as shown in FIG. 6, the cathode side of the photodiode PD1 as the light emitting element of the control signal photocoupler Pc is grounded, and the anode of the Zener diode ZD1 is connected to the anode side via a resistor. The cathode of the Zener diode ZD1 is connected to the output (terminal) 1 side. The emitter of the switching transistor Q1 ″ is connected between the cathode of the photodiode PD1 and the resistor. The collector of the switching transistor Q1 ″ is connected to Vcc via a resistor, and the base is connected to the input terminal Tmi of the switching signal Sc.
[0047]
By the way, the constant voltage control detection circuit section of the present embodiment inputs the pulse-like switching signal Sc from the input terminal Tmi, and arbitrarily blinks the constant voltage detection signal (control signal S1) to change the power supply stop state. To create. The switching method is the same as the switching methods 4 to 6 in the second embodiment described above.
[0048]
In the above-described second embodiment, the power supply stop state is created by intentionally raising and lowering the constant voltage detection signal (control signal S1) using the two-stage Zener diodes ZD1 and ZD2. The power supply stop state is controlled by blinking the light control signal S1 from the photodiode PD1 on the secondary side directly by the switching signal Sc without adding the zener diode ZD2.
[0049]
As described above, the present invention has been described with respect to the specific embodiments. However, the present invention is not limited to these, and may be applied to other embodiments within the scope described in the claims. For example, in the above embodiment, a switching transistor is provided in the constant voltage control detection circuit unit of the power supply device adopting the RCC method, and the switching transistor is turned on / off by a pulse-like switching signal to control the power stop state. However, the power supply stop state may be created by another circuit configuration or means. The point is, as apparent from a comparison between FIG. 9 (conventional example), FIG. 2 (first embodiment), and FIG. 5 (second embodiment), for example, in a power supply device adopting the RCC method, An intermittent operation mode in which the maximum output operation with high efficiency and the stop state with very small loss are repeatedly switched to operate may be taken.
[0050]
Furthermore, in the above embodiment, an example was described in which the switching signal is repeatedly switched between the maximum output operation state and the stop state, but it is not always necessary to switch between the maximum output operation state and the stop state. May be such that a predetermined operation state having a small output is set as an optimum operation state, and the optimum operation state and the stop state are switched.
[0051]
Hereinafter, the concept of the optimum operation state will be described with reference to FIGS. FIGS. 7A, 7B, and 7C are diagrams showing the relationship between the power loss of the power supply device and the output power. FIG. 7A is a diagram illustrating an example in which power supply device power loss due to an increase in output power increases quadratically. FIG. 7B is a diagram illustrating an example in which the power supply power loss accompanying an increase in the output power increases while showing a tendency to be saturated. FIG. 7C is a view similar to FIG. 3A and illustrates an example in which the power supply device power loss increases linearly (linearly) with an increase in output power.
[0052]
Here, an operation state for minimizing the average power loss when only the two states of the stop state and the operation state are repeated is referred to as an optimum operation state. In order to obtain the optimum operation state, an operation state in which the inclination angle of the line segment OB in the figure is small (slope is gentle) may be selected as the optimum operation state as shown in FIG. .
[0053]
More specifically, a power loss characteristic diagram OCABD (OCAB in FIG. 3) of the power supply device shown in FIG. The operation state corresponding to the intersection B with the tangent line tangent to the characteristic line may be selected as the optimum operation state. Therefore, in FIGS. 7B and 7C, the optimum operation state is the maximum operation state, whereas in FIG. 7A, the operation state corresponds to the output power Pbest rather than taking the operation state to the maximum operation state D point. Since the average power loss is minimized at the point B in the drawing, the point B is in the optimum operation state.
[0054]
Therefore, as shown in FIG. 7A, when the present invention is applied to a power supply device in which the power loss due to the increase in the output power increases quadratically, as shown in FIG. An operation state in which the inclination angle of the line segment OB is small (the inclination is gentle) may be determined as the optimal operation state, and the optimal operation state and the stop state may be switched.
[0055]
In order to switch the maximum output power during operation to the optimum operation state in the power supply device adopting the RCC system as in the above-described embodiment, for example, a circuit configuration as shown in FIG. 8 may be employed. That is, the constant voltage control detection circuit of the power supply device according to the fourth embodiment of the present invention further includes a maximum output power switching signal photocoupler Pmc and a switching transistor Q2 in addition to the circuit configuration shown in FIG. It has the following configuration. The maximum output power switching signal photocoupler Pmc includes a phototransistor PT3 and a photodiode PD3. As shown in FIG. 8, the anode side of the photodiode PD3 as a light emitting element of the maximum output power switching signal photocoupler Pmc is The collector of the switching transistor Q2 is connected to the cathode of the switching transistor Q2 via a resistor. The emitter side of the switching transistor Q2 is grounded, and the base is connected to the input terminal Tmi '. The maximum output power switching signal Sp is input to the input terminal Tmi '. The switching signal Sc for the intermittent operation is input to the input terminal Tmi in the same manner as in the first embodiment shown in FIG.
[0056]
The time relationship between the switching signal Sc (of the intermittent operation), the maximum output power switching signal Sp, and the maximum output power control signal S3 is, for example, an optimum operation state when the control logic of the maximum output power switching signal Sp is “H”. When the switching signal Sc (for intermittent operation) is at "L", that is, when the switching circuit is in the operating state, it is assumed that the power supply device has the original maximum output power at "L". , The maximum output power switching signal Sp only needs to be “H”. When the switching signal Sc (of the intermittent operation) is “H”, the power supply device stops the switching operation in the first place, and therefore the maximum output power switching signal Sp may be either “L” or “H”.
[0057]
In the above embodiment, the present invention has been described by taking an ink jet printer as an example. However, it is needless to say that the present invention can be widely applied not only to other printers such as a laser printer but also to other electronic devices.
[0058]
【The invention's effect】
As is apparent from the above description, the power supply device for an electronic device of the present invention has two functions, an operating state and a stopped state, in a power supply device in which continuous operation is performed under no load or light load state, the loss is increased and the efficiency is reduced. By taking the mode, the loss can be reduced as compared with the conventional continuous operation.
[0059]
Further, for example, in an RCC circuit in which the loss increases and the efficiency decreases when the operation is continuously performed in a no-load or light-load state, the maximum output operation in which the circuit is efficient and a stop state in which the loss is extremely small are repeatedly switched. By introducing the intermittent operation mode in which the operation is performed, the average output power is equivalent to a light load, but the loss can be significantly reduced as compared with the conventional continuous operation.
[Brief description of the drawings]
FIG. 1 is a diagram showing an excerpt of a constant voltage control detection circuit unit which is a main part of a power supply device according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram showing a time change of an output voltage of the circuit of FIG. 1, wherein a voltage of an output (terminal) 1 repeats a rise and a fall in accordance with a switching signal “L” and “H”; Is shown.
FIG. 3 is a diagram illustrating a relationship between power supply device power loss and output power in the case of switching methods 1 to 3 (4 to 6).
FIG. 4 is a diagram showing an excerpt of a constant voltage control detection circuit unit which is a main part of a power supply device according to a second embodiment of the present invention.
5 is a schematic diagram showing a time change of an output voltage of the circuit of FIG. 4, in which a voltage of an output (terminal) 1 repeats a rise and a fall in accordance with “L” and “H” of a switching signal; Is shown.
FIG. 6 is a diagram extracting and showing a constant voltage control detection circuit unit which is a main unit of a power supply device according to a third embodiment of the present invention.
7A and 7B are diagrams illustrating a relationship between power supply device power loss and output power, wherein FIG. 7A illustrates an example in which power supply device power loss increases quadratically with increase in output power, and FIG. 7B illustrates output power increase. (C) is a diagram for explaining an example in which the power supply device power loss accompanying the increase in output power increases while showing a tendency to saturate, and FIG.
FIG. 8 is a diagram showing an excerpt of a constant voltage control detection circuit unit which is a main part of a power supply device according to a fourth embodiment of the present invention.
FIG. 9 is a circuit diagram of a constant voltage control detection circuit portion of a general RCC type power supply device.
FIG. 10 is a schematic diagram showing a time change of an output voltage of the circuit of FIG. 9;
FIG. 11 is a diagram generally explaining the breakdown of power loss of the power supply device.
FIGS. 12A and 12B are diagrams showing the factors that cause the switching loss power of the switching element; FIG. 12A shows the factors that cause the switching loss power of the switching element under a large load; and FIG. 12B shows the switching loss of the switching element under a light load. This shows the power generation factor.
[Explanation of symbols]
ZD1 Zener diode
PD1 photodiode
S1 control signal
S2 stop signal
PT1 Phototransistor
43 Transformer
Q44 Switching transistor for AC generation
Photocoupler for Pc control signal
CC primary side control circuit
Ps Stop signal photocoupler
Q1 switching transistor
PD2 photodiode
PT2 Phototransistor
Tmi input terminal
Sc switching signal
ZD2 Zener diode
Q1 'switching transistor
Q1 '' switching transistor
Pmc Photocoupler for maximum output power switching signal
Q2 switching transistor
PT3 Phototransistor
PD3 photodiode
Tmi 'input terminal
Sp maximum output power switching signal
S3 Maximum output power control signal

Claims (11)

An electronic device power supply device capable of taking an intermittent operation mode that repeats an operation state and a stop state when the electronic device is in a no-load or light-load state in a state where the electronic device is powered on,
An output voltage control circuit that controls an output voltage;
Input means for inputting a switching signal generated according to the output voltage,
Switching means for switching the operation and stop of the output voltage control circuit in accordance with the switching signal,
The power supply device for an electronic device, wherein the output voltage control circuit controls the output voltage when the operating state is set by the switching means . 2. The power supply device for an electronic device according to claim 1, wherein the output voltage control circuit performs a maximum operation when the output voltage control circuit is activated by the switching unit . 3. The power supply device for an electronic device according to claim 1, wherein a ringing choke converter circuit system is adopted, wherein the operation state is an optimum operation state in which the ringing choke converter circuit is efficient, and the intermittent operation mode is the optimum operation state. A power supply device for an electronic device, wherein the power supply device is operated by repeatedly switching between a state and a stop state with extremely small loss by the pulse-like switching signal . 4. The power supply device for an electronic device according to claim 3, wherein the optimum operation state is a maximum output operation state . 5. The power supply device for an electronic device according to claim 1, wherein the switching signal is switched at predetermined time intervals after the output voltage reaches a maximum output . 5. The power supply device for an electronic device according to claim 1, wherein the switching signal switches when the output voltage reaches a maximum output . 5. The power supply device for an electronic device according to claim 1, wherein the switching signal switches before the output voltage reaches a maximum output . 8. The power supply device for an electronic device according to claim 1, wherein a detected voltage of the constant voltage detection signal is arbitrarily raised and lowered between a first voltage and a second voltage lower than the first voltage. A power supply device for an electronic device, wherein the power supply device takes an intermittent operation mode in which the operation state and the stop state are repeated . 9. The power supply device for an electronic device according to claim 8, wherein the switching means requires a first predetermined time for an output voltage of the output voltage control circuit to rise from the second voltage to a first voltage, When a second predetermined time is required for the output voltage of the output voltage control circuit to fall from the first voltage to the second voltage by the switching means, a time when the switching signal is at a low level is a first predetermined time. A power supply device for an electronic device , wherein the switching signal is at a high level for a time longer than a second predetermined time . 9. The power supply device for an electronic device according to claim 8, wherein the switching means requires a first predetermined time for an output voltage of the output voltage control circuit to rise from the second voltage to a first voltage, When a second predetermined time is required for the output voltage of the output voltage control circuit to fall from the first voltage to the second voltage by the switching means, a time when the switching signal is at a low level is a first predetermined time. A power supply device for an electronic device , wherein a time during which the switching signal is at a high level is equal to a second predetermined time . 9. The power supply device for an electronic device according to claim 8, wherein the switching means requires a first predetermined time for an output voltage of the output voltage control circuit to rise from the second voltage to a first voltage, When a second predetermined time is required for the output voltage of the output voltage control circuit to fall from the first voltage to the second voltage by the switching means, a time when the switching signal is at a low level is a first predetermined time. A power supply apparatus for an electronic device , wherein the time is shorter than a time and the time when the switching signal is at a high level is shorter than a second predetermined time .

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