JP2010093912A - Power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a specific constitution which surely charges a battery unit by DC power fed to a body device from an AC adapter, when the body device is brought into a power-off state. <P>SOLUTION: When a power supply 31 for power supply attached to the body device 2 in the power-off state is charged, a power feed control terminal 1b is initially controlled to a low level until a charging/discharging capacitor 205 is charged to a constant voltage, by using the voltage of an output terminal 1a of the AC adapter 1, and the DC power supply of the AC adapter 1 is initially controlled to a power supply voltage of the body device 2, which is necessary for charging the power supply 31 for power supply. Then, the power feed control terminal 1b is held at a low level by starting a charging circuit 204, and the DC power supply of the AC adapter 1 is maintained at the power supply voltage of the body device 1. Furthermore, when the power supply plug of the AC adapter 1 is wrongly pulled out of a power receptacle and reinserted into it and so forth, the power feed control terminal 1b is initially controlled, without fail, to the low level by sort-circuiting and discharging the charging/discharging capacitor 205 by using a reset circuit 218. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention supplies power to the main unit with a DC power source of the AC adapter and a battery unit detachably attached to the main unit with priority given to power supply from the AC adapter to the main unit, and the main unit is turned off. It is related with the power supply device which charges a battery unit with the direct-current power supply of an AC adapter in the state of this.

  2. Description of the Related Art Conventionally, there are various electronic devices such as printers and projectors that supply DC power from an AC adapter to a main unit. Further, in these electronic devices, portable type devices such as an ink jet printer for photo printing (hereinafter referred to as a photo printer) have a battery unit (also called a battery pack) with a secondary battery as an optional unit. When the battery unit is attached, DC power is supplied from the AC adapter and the battery unit to the main unit with priority given to the power supply from the AC adapter. Further, the secondary battery of the battery unit is charged by a DC power source that is fed from the AC adapter to the main unit when the main unit is in a power-off state (see, for example, Patent Document 1).

JP-A-2003-72057 (paragraphs [0002]-[0007], [0024]-[0041], [0061], FIG. 3 and the like).

  In the portable electronic device such as the photo printer described above, a direct current power source that supplies power to the main unit from an AC adapter and a battery unit is provided in order to reduce the size of the main unit, reduce costs, save power, and take environmental measures. Is set to the power supply voltage of the main unit, and it is desired not to provide a booster DC-DC converter or the like in the main unit. Furthermore, if the power supply voltage of the main unit is relatively high, for example, around 40V, power loss and safety in the AC adapter formed in the switching power supply, startup when the main unit changes from power off to power on Considering the characteristics and the like, it is preferable to switch the output voltage of the AC adapter to a voltage (idle voltage) lower than the power supply voltage when the main apparatus is turned off.

  However, when the output voltage of the AC adapter is switched between high (power supply voltage) and low (idle voltage) depending on the power on / off state of the main unit, when the main unit enters the power off state, the AC adapter switches from the AC adapter to the main unit. It is conceivable that the DC power supply to be fed is lowered to the idle voltage and it becomes difficult to charge the secondary battery of the battery unit.

  In this type of power supply, the output voltage of the AC adapter is switched between high and low depending on whether the main apparatus is turned on or off, and power is supplied from the AC adapter to the main apparatus when the main apparatus is in the power off state. No specific configuration has been invented for reliably charging the secondary battery of the battery unit with a direct current power source.

  According to the present invention, in a power supply device for an electronic device such as a photo printer, the output voltage of an AC adapter is switched between high and low depending on the power-on and power-off states of the main device, and when the main device is in a power-off state, It is an object of the present invention to provide a specific configuration in which a secondary battery of a battery unit is reliably charged by a DC power source that is fed from an adapter to a main unit.

  In order to achieve the above object, a power supply device according to the present invention includes a DC power source for an AC adapter and a DC power source for a battery unit that is detachably attached to the main unit, with priority given to power supply from the AC adapter. Based on the charging control when the main unit is powered off and the main unit is powered off, the power source battery of the secondary battery configuration of the battery unit mounted on the main unit is charged by the DC power source of the AC adapter. The AC adapter converts an input AC power source into a DC power source, and supplies a DC power source from the output terminal of the AC adapter to the main unit, and a voltage at the output terminal The main body device is applied through a resistor, and when the main body device is in a power-on state and when the main body device is charged in the power-off state, the main body device is charged The power supply control terminal controlled to a lower level, and the voltage of the DC power supply of the regulator unit is controlled to the power supply voltage of the main body device by the low level of the power supply control terminal, and the regulator unit is controlled by the high level of the power supply control terminal And an output control unit that controls the voltage of the DC power supply to an idle voltage lower than the power supply voltage, and the main body device has one end when the AC adapter is connected with the battery unit mounted. The power supply control terminal is connected and the other end is grounded via the battery unit and is charged by the voltage of the output terminal via the power supply control terminal, and the power supply control terminal is low during charging from the discharged state. A charge / discharge capacitor that is initially controlled to a level, and a discharge path that is drawn from one end of the charge / discharge capacitor when the power is on. First level holding means for holding the power supply control terminal at a low level, and a DC power source of the power supply voltage of the AC adapter based on the initial control, and the discharge path when charging the power supply battery Grounding and holding the power supply control terminal at a low level, and second level holding means for returning the discharge path to non-ground due to loss of power supply from the AC adapter, and the power supply from the AC adapter based on the loss of power supply Reset means for resetting the charge / discharge capacitor to the discharge state by short-circuiting the charge / discharge capacitor due to a voltage drop at the output terminal.

  Therefore, according to the power supply device of the present invention, when the AC adapter is connected to the main unit with the battery unit mounted on the main unit, the power supply control terminal, the charging / discharging capacitor of the main unit, the battery are connected from the output terminal of the AC adapter. A charging path for the charging / discharging capacitor to the ground through the unit is formed, the charging / discharging capacitor is charged with the voltage of the output terminal of the AC adapter, and the power feeding control terminal is charged until the charging / discharging capacitor is charged from the discharged state to a constant voltage. Initially controlled to low level. If the main unit is in a power-on state at this time, one end of the charge / discharge capacitor is grounded via the discharge path by the first level holding means, the charge / discharge capacitor is discharged, and the power supply control terminal is held at the low level. . Therefore, a DC power supply of the power supply voltage of the main device is supplied from the AC adapter to the main device, and the main device operates with the DC power supplied from the AC adapter.

  If the power supply control terminal is initially controlled to a low level and the main unit is in a power-off state, the second level holding means is provided by the DC power supply of the output terminal of the AC adapter that is initially controlled to the power supply voltage of the main unit. Is activated. When charging the battery for power supply of the battery unit, one end of the charge / discharge capacitor is grounded via the discharge path by the second level holding means, the charge / discharge capacitor is discharged, and the power supply control terminal is held at the low level. Then, the AC power is supplied from the AC adapter to the main unit, and the power source battery of the battery unit is charged with the DC power of the main unit.

  By the way, while the charging / discharging capacitor is being charged from the discharge state with the voltage of the output terminal of the AC adapter, the AC adapter power plug is pulled out from the power outlet and reinserted into the power outlet, or the AC power supply of the power outlet is turned off. When there is a momentary power failure, the AC adapter output terminal even while the power plug is pulled out of the power outlet or while the AC power supply of the power outlet is out of power, that is, while the AC adapter input is interrupted The charging of the charging / discharging capacitor progresses due to the voltage of the AC adapter, and after the power supply control terminal is reversed to a high level, the AC adapter power plug is re-inserted into the power outlet, or the AC power supply of the AC outlet is restored and the AC adapter input is restored. A situation to resume will occur. At this time, if the charging / discharging capacitor is further charged with the voltage of the output terminal of the AC adapter, the power supply control terminal does not become low level, and the DC power supply of the output terminal of the AC adapter is not initially controlled to the power supply voltage. The unit power supply battery cannot be charged.

  However, in the case of the power supply device of the present invention, the AC adapter power plug is pulled out from the power outlet and reinserted into the power outlet while the charging / discharging capacitor is being charged from the discharged state with the voltage of the output terminal of the AC adapter. If the AC power supply of the power outlet is momentarily interrupted, the input of the AC adapter is interrupted and the voltage at the output terminal of the AC adapter drops from the power supply voltage, causing the reset means to short-circuit and discharge the charge / discharge capacitor. Reset to discharged state. For this reason, whenever the power plug of the AC adapter is re-inserted into the power outlet or the input of the AC adapter is restarted, the charge / discharge capacitor is always charged from the discharged state, and the power supply control terminal is initially controlled to the low level. And the power supply control terminal is held at a low level, and the battery for power supply of the battery unit is reliably charged with the DC power supply of the power supply voltage supplied from the AC adapter to the main unit.

  Therefore, according to the power supply device of the present invention, when the power supply of the main unit is off, the battery for power supply of the battery unit can be reliably charged by the DC power supplied from the AC adapter to the main unit. The output voltage is switched between the power supply voltage (high) and idle voltage (low) of the main unit depending on whether the main unit is turned on or off, and when the main unit is turned off, power is supplied from the AC adapter to the main unit. Therefore, it is possible to provide a specific configuration in which the battery for power supply of the battery unit can be reliably charged by the direct current power source.

  Next, in the power supply device according to the present invention, the second level holding unit is activated by a DC power supply of the power supply voltage of the AC adapter, and the operation of the power supply battery is stopped when power supply from the AC adapter is lost. A charging circuit that is turned on by controlling the charging circuit to ground the discharge path when charging the power supply battery, and is turned off by stopping the operation of the charging circuit to return the discharging path to non-grounding. And a control semiconductor switch.

  In this case, when the power supply control terminal is initially controlled to the low level, the power supply battery charging circuit is activated by the DC power supply of the power supply voltage of the AC adapter based on the low level. During charging of the power supply battery, the charging circuit turns on the discharge path control semiconductor switch, grounds the discharge path and holds the power supply control terminal at a low level, and uses the DC power supply of the AC adapter power supply voltage for power supply. The battery can be charged. Therefore, it is possible to provide a more specific configuration that can reliably charge the battery for power supply of the battery unit when the power supply of the main unit is off.

  Next, in the power supply device of the present invention, the reset means is charged to a reference voltage lower than the power supply voltage by a DC power supply of the output terminal, and the voltage of the output terminal is changed based on the disappearance of power supply from the AC adapter. A reset timing setting capacitor that is disconnected from the output terminal in the previous period and discharges with a time constant set so that the drop in the terminal voltage is slower than the voltage drop in the output terminal when the voltage falls below the reference voltage, and the terminal voltage A short-circuit semiconductor switch that is turned on when the voltage of the output terminal becomes higher than the voltage of the output terminal and short-circuits between the terminals of the charge / discharge capacitor.

  In this case, the AC adapter is connected to the main unit with the battery unit attached to the main unit, and the charging / discharging capacitor is charged from the discharged state with the voltage of the output terminal of the AC adapter. The reset timing setting capacitor is charged to a reference voltage lower than the power supply voltage by the DC power supply. When the AC adapter power plug is pulled out of the power outlet or the AC power supply of the power outlet is momentarily interrupted, the input voltage of the AC adapter is interrupted. When the terminal voltage of the charging / discharging capacitor becomes higher than the voltage of the output terminal of the AC adapter due to the voltage drop at the output terminal of the AC adapter due to the voltage drop at the output terminal of the AC adapter, the shorting semiconductor switch is turned on and the terminal of the charging / discharging capacitor The charge / discharge capacitor is reset to the discharge state by short-circuiting the gap. Therefore, when the AC adapter power plug is re-inserted into the power outlet or AC power supply is restored and AC adapter input resumes, the charge / discharge capacitor is always charged from the discharged state and the power supply control terminal is at the low level. The battery for power supply of the battery unit is reliably charged with the direct current power source of the power source voltage that is initially controlled to be supplied to the main unit from the AC adapter.

  Therefore, it is possible to provide an even more specific configuration in which the power source battery of the battery unit can be reliably charged by the DC power supplied from the AC adapter to the main unit when the main unit is powered off. it can.

  An embodiment of the present invention will be described in detail with reference to FIGS. 1 is a connection diagram of a power supply device of a photo printer as an example of an electronic device, FIG. 2 is a detailed connection diagram of the AC adapter 1 of FIG. 1, and FIGS. 3 to 6 are timing charts for explaining operations.

  In the power supply device of the present embodiment shown in FIG. 1, the AC adapter 1 is formed in the flyback type switching power supply shown in FIG. A battery unit 3 as an optional unit is detachably attached to the main body device 2.

  Then, the AC adapter 1 will be described with reference to FIG. 2. When the AC plug 100 is inserted into a power outlet, an AC power source of 230 V, for example, is connected to the AC formed by the fuse 101, the capacitor 102, and the coil 103. The AC power is input to the rectifier circuit 105 of the diode bridge of the input processing unit 104 through the filter, and the AC power is rectified and smoothed by the rectifier 105 and the smoothing capacitor 106 to form a DC power supply on the high voltage input side. Further, the DC power supply on the input side is supplied to the primary winding 108 a on the primary side of the transformer 108 via the snubber circuit 107. Then, an N-channel MOS type FET 109 connected in series to the first winding 108 a performs high-frequency switching by the switching control unit 110 to interrupt the input-side DC power supply, and the secondary winding of the secondary side of the transformer 108. A pulse output of a voltage corresponding to the turn ratio of the windings 108 a and 108 b is induced in 108. The FET 109 has a drain connected to the first winding 108 a, a source grounded, and a gate connected to the control terminal G of the switching control unit 110.

  Then, the pulse output of the second winding 10b is rectified and smoothed by the diode 112 and the smoothing capacitor 113 of the output processing unit 111, and when the main unit 2 is in the power-on state, the direct current on the output side of the power source voltage (42V) of the main unit 2 A power supply is formed. This DC power supply on the output side is fed from the output terminal 1a to the AC adapter terminal 2a of the main unit 2. Further, the voltage detection unit 114 at the subsequent stage of the output processing unit 111 detects the voltage of the DC power supply on the output side. The optical signal is fed back to the switching control unit 110. The phototransistor 115b has a collector connected to the feedback terminal FB of the switching control unit 110, and an emitter grounded.

  The switching control unit 110 includes, for example, a well-known control IC for switching power supply, and feedback-controls the high-frequency switching of the FET 109 so that the voltage of the detection result becomes a setting voltage for feedback control, so that the output-side DC power supply The voltage is controlled to the power supply voltage or the idle voltage described later. In the voltage detector 114, a resistor 116, a photodiode 115a, a collector and emitter of an NPN transistor 117 for current adjustment, and a Zener diode 118 for temperature characteristic correction are connected in series between the output terminal 1a and the ground. The detection transistor 117 has a base to which a bias voltage obtained by dividing the output voltage of the output processing unit 111 by resistors 119 and 120 is applied. The amount of current flowing through the photodiode 115a (and the amount of emitted light) is proportional to the voltage of the DC power supply on the output side.

  By the way, the most characteristic point of the AC adapter 1 is that a power supply control terminal 1b connected to the terminal 2b of the main device 2 and a detection correction unit 121 are provided.

  The power supply control terminal 1b is connected to the output terminal 1a via the resistor 122 of the detection correction unit 121, and is set to about 1.4 V (for example, considering a forward voltage drop of the diode) by the control of the main body device 2. As a threshold voltage Vα, a voltage slightly higher than the first voltage) is changed to a high level (hereinafter referred to as H) and a low level (hereinafter referred to as L). The detection correction unit 121 includes an N-channel CMOS type FET 123 that switches according to a change in the level of the power supply control terminal 1b. The FET 123 has a drain connected to the cathode of the photodiode 115a, a source grounded, and a gate controlled power supply. In addition to being connected to the terminal 1 b, it is connected to a connection point between the resistor 122 and the cathode of the Zener diode 124. The Zener diode 124 has an anode grounded and a cathode connected to the output terminal 1a via a resistor 122. The ground terminal 1 c of the AC adapter 1 is connected to the ground terminal 2 c of the main device 2. The input processing unit 104, the transformer 108, the FET 109, and the output processing unit 111 form the regulator unit 125 of the present invention, and the switching control unit 110, the voltage detection unit 114, the photocoupler 115, and the detection correction unit 121 output the present invention. A control unit 126 is formed.

  In the AC adapter 1 having the above configuration, when the power plug 100 is inserted into a power outlet in a state where the terminals 1a to 1c are connected to the terminals 2a to 2c of the main unit 2 through the power supply cord 1d, the FET 109 performs high-frequency switching. The pulse output of the second winding 108b of the transformer 108 is rectified and smoothed by the output processing unit 111 to form a DC power source, and this DC power source is fed from the output terminal 1a to the AC adapter terminal 2a of the main unit 2.

  When the main unit 2 is in a power-on state and when the power source battery 31 having the secondary battery configuration of the battery unit 3 is charged, that is, when a power supply state with a load is entered, the power supply control terminal 1b becomes L. Since the FET 123 is turned off, the detection correction unit 121 detects that the power supply state is loaded. At this time, the FET 123 does not affect the detection of the voltage detection unit 114, and the voltage detection unit 114 changes the conduction current of the photodiode 115a in proportion to the voltage of the output terminal 1a based on the change of the collector-emitter voltage of the transistor 117. Then, the light emission amount of the photodiode 115 a and the light reception amount of the phototransistor 115 b change in proportion to the output voltage of the output processing unit 111. Then, based on the error between the level of the feedback terminal FB and the level of the set voltage for feedback control, the switching control unit 110 feeds back the high-frequency switching of the FET 109 so that the output voltage of the output processing unit 111 becomes the set voltage (42V). Then, a DC power supply of the power supply voltage (42 V) of the main unit 2 necessary for the operation of the main unit 2 and the charging of the battery 31 for the battery unit 3 is supplied to the main unit 2 from the output terminal 1a.

  On the other hand, when it is not necessary to charge the power source battery 31 of the battery unit 3 when the main unit 2 is in the power-off state, that is, when the no-load power supply state is entered, the power supply control terminal 1b becomes H and the FET 123 is turned on. Since it turns on, the detection correction part 27 detects that it is a no-load electric power supply state. At this time, the bypass path of the FET 123 is formed in parallel with the energization path of the transistor 117 and the Zener diode 118 on the cathode side of the photodiode 115a.

  The cathode potential of the photodiode 115a decreases due to the formation of the bypass path, the energization current of the photodiode 115a increases, and the detection result of the voltage detection unit 114 is corrected to be higher than the actual output voltage of the output processing unit 18. . By this correction, the light emission amount of the photodiode 115a increases and the light reception amount of the phototransistor 115b also increases. Further, the switching control unit 110 feedback-controls the high frequency switching of the FET 109 based on the corrected detection result of the voltage detection unit 111, and the output voltage of the AC adapter 1 is set to an appropriate voltage lower than the power supply voltage (42V), Specifically, it is controlled to an idle voltage of 20V that is safe, consumes less power, and is friendly to the environment.

  Next, the battery unit 3 that is detachably attached to the main unit 2 will be described with reference to FIG. 1. The power source battery 31 built in the battery unit 3 is composed of, for example, a lithium ion battery (secondary battery). The output voltage is 14.8V, for example. The power supply battery 31 may be boosted by the main body device 2, but the battery unit 3 is an optional unit, and the main body device 2 can be reduced in size, weight, and saving when the battery unit 3 is used without being attached. In the present embodiment, from the viewpoint of achieving electric power and the like, in the battery unit 3, a boosting processing unit 32 including a boosting processing circuit such as a boosting DC-DC converter and a control circuit thereof is built in.

  Then, the DC power source formed by boosting the output of the power source battery 31 by the boosting processing unit 32 is fed from the output terminal 3d of the battery unit 3 to the cathode side of the backflow prevention diode 201, but a power failure or the like of the AC power source occurs. When the DC power supply of the AC adapter 1 is lost, the AC adapter 1 is switched from the DC power supply of the AC adapter 1 to the DC power supply of the battery unit 3 without stopping the power supply to the main apparatus 2. During power feeding from the main unit 2 to the main unit 2, the boost processing unit 32 causes the voltage of the DC power source of the output terminal 3 d to be a voltage corresponding to the lower limit power source voltage of the main unit 2 slightly lower than the 42 V DC power source of the output terminal 1 a of the AC adapter 1. (For example, 36V). Further, when the backflow prevention diode 201 is turned off and the main unit 2 is operated by the DC power supply of the battery unit 3, the boost processing unit 32 raises the voltage of the DC power supply of the output terminal 3d to the power supply voltage (42V).

  The positive electrode of the power supply battery 31 is connected to the charging circuit 204 provided in the main body device 2 through the charging input terminal 3a. When the main body device 2 is in the power off state, the charging circuit 204 is connected to the terminal voltage of the power supply battery 31 and the like. If it is determined that charging of the power source battery 31 is necessary, the DC power source of the output terminal 1a of the AC adapter 1 via the AC adapter terminal 2a is stepped down to an appropriate charging voltage, and the power source battery 31 is reduced by this charging voltage. To charge.

  Next, the main unit 2 will be described with reference to FIG. 1. In order to initially control the power supply control terminal 1b of the AC adapter 1 to L, one end on the positive electrode side of the charge / discharge capacitor 205 is connected to the terminal 2b of the main unit 2. The other end on the negative electrode side of the charge / discharge capacitor 205 is grounded via the backflow prevention diode 206 of the charging path 207, the connection terminal 3b of the battery unit 3, and the ground terminal 3c.

  When the power plug 100 of the AC adapter 1 connected to the main unit 2 is inserted into the power outlet, the voltage of the output terminal 1a of the AC adapter 1 rises, the charging current is the resistance 107, the power supply control terminal 1b, the charge / discharge. The control power supply terminal 1b is initially controlled to L until it flows to the ground through the capacitor 205 and the backflow prevention diode 206 and is charged to the threshold voltage Vα by the charging current.

  Further, a discharge path 208 is drawn from one end of the charge / discharge capacitor 205, and the discharge path 208 is a reverse current prevention diode 209 in order from one end side of the charge / discharge capacitor 205, an NPN normally-on overcurrent protection transistor 210, Backflow prevention diodes 211 and 212 having anodes connected to the emitter of the overcurrent protection transistor 210 are provided. The cathode of the backflow prevention diode 211 is grounded via the power switch 200, and the cathode of the backflow prevention diode 212. Is grounded via the collector and emitter of the NPN transistor 213 forming the first level holding means of the present invention, and the NPN forming the discharge path control semiconductor switch of the second level holding means of the present invention Grounded via the collector and emitter of transistor 214 To have.

  The power switch 200 is a self-returning type switch and alternately changes to a power-on operation and a power-off operation each time it is pressed. When the power switch 200 is turned on and the main unit 2 is in a power-on state, the on operation is latched by the system controller 215 having a microcomputer configuration that controls the overall operation of the main unit 2, and the charge / discharge capacitor Before 205 is charged to the threshold voltage Vα, the system control unit 215 turns on the transistor 213 to ground the discharge path 208, and one end of the charge / discharge capacitor 205 is connected to the backflow prevention diode 209 and the overcurrent protection transistor 210. The backflow prevention diode 212 and the transistor 213 are grounded. Therefore, while the main unit 2 is in the power-on state, the power supply control terminal 1b at one end of the charge / discharge capacitor 205 is controlled to L, and the voltage at the output terminal 1a of the AC adapter 1 is maintained at the power supply voltage (42V). The main unit 2 is operated by a DC power source having a power source voltage (42 V) of the AC adapter 1 to perform printing or the like.

  On the other hand, when charging the power source battery 31 of the battery unit 3 attached to the main unit 2 with the main unit 2 powered off, the charging / discharging capacitor 205 is charged before being charged from the discharged state to the threshold voltage Vα. The circuit 204 turns on the transistor 214 to ground the discharge path 208, and grounds one end of the charge / discharge capacitor 205 through the backflow prevention diode 209, the overcurrent protection transistor 210, the backflow prevention diode 212, and the transistor 214. Therefore, even when the main unit 2 is in the power-off state, the power supply control terminal 1b of the battery unit is controlled to L, the voltage of the output terminal 1a of the AC adapter 1 is maintained at 42V, and the 42V of the output terminal 1a is maintained. The power source battery 31 of the battery unit 3 is charged by the output of the charging circuit 204 based on the DC power source. When the charging of the power supply battery 31 is completed, the charging circuit 204 that detects the completion of charging from the terminal voltage of the power supply battery 31 turns off the transistor 214 and disconnects the discharge path 208 from the ground. When the charging / discharging capacitor 205 is charged by this disconnection and the terminal voltage becomes equal to or higher than the threshold voltage Vα, the power supply control terminal 1b is inverted to H and the voltage at the output terminal 1a of the AC adapter 1 is reduced to the idle voltage. To do.

  Note that the overcurrent protection transistor 210 is configured so that when the DC power supplied from the AC adapter 1 is in an overcurrent state for some reason, the system control unit 215 that detects the overcurrent using, for example, a current sensor When the NPN transistor 216 is turned on, the base voltage pulled up by the resistor 217 is lowered and turned off, the discharge path 208 is released from the ground state, and the power supply control terminal 1b is inverted from L to H to AC. Reduce the voltage of the DC power supply of the adapter 1.

  Accordingly, the power supply control terminal 1b of the AC adapter 1 is controlled to H and L by the main body device 2, and the power source battery 31 of the battery unit 3 is charged when the main body device 2 is powered on and when the main body device 2 is powered off. When the power is supplied, a DC power of a power supply voltage (42 V) is supplied from the AC adapter 1 to the main unit 2 by H of the power supply control terminal 1b. When the main unit 2 is in a power-on state, the main unit 2 is operated by a DC power source having a supplied power source voltage (42V), and when the power source battery 31 is charged, a DC power source having a supplied power source voltage (42V) is provided. The power supply battery 31 is charged by the output of the charging circuit 204 based on the above.

  By the way, if the main body device 2 is not provided with the reset circuit 218 of FIG. 1 as the reset means of the present invention described below, when the power source battery 31 of the battery unit 3 is charged in the power-off state of the main body device 2, When the power plug 100 of the AC adapter 1 is accidentally pulled out from the power outlet and re-inserted into the power outlet, or when the AC power supply of the power outlet is momentarily stopped (momentary interruption), the power supply battery 31 is charged. Invite a situation that does not happen.

  That is, if the main unit 2 is not provided with the reset circuit 218, the power supply of the AC adapter 1 when the power plug 100 is inserted into the power outlet and the charge / discharge capacitor 205 is charged to about the threshold voltage Vα (time ta). If the plug 100 is accidentally pulled out from the power outlet, and then the power plug 100 is reinserted into the power outlet at time tb without waiting for several seconds for the charge / discharge capacitor 205 to spontaneously discharge, the AC adapter in between 1 does not reach the power supply voltage (42V) as shown by the solid line in FIG. Further, the transistor 241 is held off and the discharge path 208 is not grounded, and the terminal voltage of the charge / discharge capacitor 205 becomes equal to or higher than the threshold voltage Vα as shown by the solid line in FIG. For this reason, the power supply control terminal 1b is not initially controlled to L after the power plug 100 is reinserted, and the DC power supplied from the AC adapter 1 to the main unit 2 is maintained at the idle voltage (20V) and the power supply battery 31 Charging is not performed. Similarly, when the power supply plug 100 is inserted into a power outlet and the charging / discharging capacitor 205 is charged up to about the threshold voltage Vα, if the AC power supply of the power outlet is momentarily interrupted (instantaneous power interruption), then AC The voltage at the output terminal 1a of the adapter 1 does not reach the power supply voltage (42V), the transistor 214 is turned off, and the discharge path 208 is not grounded. For this reason, the terminal voltage of the charge / discharge capacitor 205 is already equal to or higher than the threshold voltage Vα immediately after the power failure is restored, and the power supply control terminal 1b is not initially controlled to L after the power failure is restored. The supplied DC power source is maintained at an idle voltage, and the power source battery 31 is not charged.

  Thus, in the present embodiment, the main body device 2 is provided with a reset circuit 218. The reset circuit 218 includes an NPN transistor 219 having a collector and an emitter connected to both ends of the charge / discharge capacitor 205 and forming a short-circuiting semiconductor switch according to the present invention, and a base circuit thereof.

  The base circuit of the transistor 219 includes a reset timing setting unit 220, an NPN transistor 221 that is switched when the base voltage is controlled by the reset timing setting unit 220, and a PNP that is switched when the base voltage is controlled by the collector voltage of the transistor 221. Transistor 222. The reset timing setting unit 220 includes a backflow prevention diode 223 connected to the AC adapter terminal 2a in the forward direction, a resistor 224 provided in series between the cathode of the diode 223 and the ground, and the reset timing setting of the present invention. And a discharge time constant resistor 226 connected in parallel to the capacitor 225.

  The base of the transistor 221 is connected to the cathode of the backflow prevention diode 223, and the emitter is connected to the AC adapter terminal 2a. The base of the transistor 222 is connected to the collector of the transistor 221 via the resistor 227, and the emitter is connected to the connection point between the resistor 224 of the reset timing setting unit 220 and the reset timing setting capacitor 225, that is, the reference voltage point R. A bias resistor 228 is connected between the base and the emitter. Further, the base of the transistor 219 is connected to the collector of the transistor 222 via the resistor 229, and a bias resistor 230 is provided between the base and the emitter.

  When charging the power supply battery 31 of the battery unit 3 with the power of the main unit 2 off, the power plug 100 is inserted into a power outlet, and the charge / discharge capacitor 205 is thresholded by the voltage of the output terminal 1a of the AC adapter 1. When the battery is charged to the value voltage Vα (time tx), the power plug 100 of the AC adapter 1 is mistakenly pulled out from the power outlet, and then the charge / discharge capacitor 205 does not wait for several seconds to naturally discharge. If the power plug 100 is reinserted into the power outlet at ty, the voltage at the output terminal 1a of the AC adapter 1 changes as shown by the solid line a in FIG. Further, until the power plug 100 of the AC adapter 1 is pulled out from the power outlet, the backflow prevention diode 223 and the resistor 224 of the reset timing setting unit 220 are driven by the voltage of the output terminal 1a of the AC adapter 1 through the AC adapter terminal 2a. Through this charging, the reset timing setting capacitor 225 is charged, and the reference voltage Vr at the reference voltage point R becomes a specified voltage of, for example, 20 V as shown by the solid line b in FIG. Further, while the reset timing setting capacitor 225 is charged, the backflow prevention diode 223 is turned on, and the transistor 221 is held in the reverse bias state and turned off. When the transistor 221 is turned off, the transistors 222 and 219 are turned off. When the transistor 219 shown in FIG. 4C is turned off, the charge / discharge capacitor 205 is held in a charged state, and the terminal voltage thereof is shown by a solid line in FIG. Ascend as shown.

  Next, when the power plug 100 is pulled out from the power outlet, the voltage of the output terminal 1a of the AC adapter 1 through the AC adapter terminal 2a is lowered. When the reference voltage Vr becomes higher than the voltage at the output terminal 1 a of the AC adapter 1 at time ton in FIG. 4, the backflow prevention diode 223 is turned off, and the reset timing setting capacitor 225 is discharged via the discharge time constant resistor 226. To do. Based on the setting of the discharge time constant, the voltage of the output terminal 1a of the AC adapter 1 is restored by reinsertion of the power plug 100, and the voltage of the output terminal 1a of the AC adapter 1 becomes higher than the reference voltage Vr in FIG. Until toff, the reference voltage Vr is higher than the voltage of the output terminal 1a of the AC adapter 1, and the backflow prevention diode 223 is kept off. Then, while the backflow prevention diode 223 is kept off, the transistor 211 is turned on and the transistors 222 and 219 are turned on. Further, when the transistor 219 is turned on, the terminals of the charge / discharge capacitor 205 are short-circuited by the transistor 219, and the charge / discharge capacitor 205 is short-circuited.

  Therefore, when the power plug 100 is reinserted into the power outlet (time ty in FIG. 4), the charge / discharge capacitor 205 is always in a discharged state even if the discharge path 208 is not grounded, and the AC adapter The charge / discharge capacitor 205 is charged from the discharge state with the voltage of the output terminal 1a. Until the charging / discharging capacitor 205 is charged to the threshold voltage Vα, the power supply control terminal 1b is initially controlled at L, and the AC adapter 1 is supplied with the DC power of the power supply voltage (42V) from the AC adapter 1 to the main unit 2. Then, the power source battery 31 is charged.

  Similarly, when an instantaneous interruption (instantaneous power interruption) of the AC power supply of the power outlet occurs when the power plug 100 is inserted into the power outlet and the charge / discharge capacitor 205 is charged to about the threshold voltage Vα, the reference voltage point R Is set to the reference voltage Vr, the reset timing setting capacitor 225 is discharged. Then, from the occurrence of a momentary interruption (instantaneous power failure) to the recovery of the power failure, the reference voltage Vr becomes higher than the voltage of the output terminal 1a of the AC adapter 1 and the backflow prevention diode 223 is maintained off, and the transistor 221 Is turned on and the transistors 222 and 219 are turned on. Therefore, when the terminals of the charging / discharging capacitor 205 are short-circuited by the transistor 219 and the charging / discharging capacitor 205 is short-circuited to recover from a power failure, the output terminal 1a of the AC adapter 1 is not grounded even if the discharge path 208 is not grounded. Until the charging / discharging capacitor 205 is charged from the discharged state by the voltage and the charging / discharging capacitor 205 is charged to the threshold voltage Vα, the power supply control terminal 1b is initially controlled to be L and the power source battery 31 is charged. Is called.

  Therefore, when the AC adapter 1 is connected to the main unit 2 with the battery unit 3 attached to the main unit 2 and the charge / discharge capacitor 205 is charged with the voltage of the output terminal 1a of the AC adapter 1, the AC adapter 1 If the power plug 100 is accidentally pulled out of the power outlet and re-inserted into the power outlet, or if the AC power supply at the power outlet momentarily fails, the output of the AC adapter 1 is interrupted while the input of the AC adapter 1 is interrupted. The voltage at the terminal 1a drops faster than the terminal voltage of the reset timing setting capacitor 225, and the terminal voltage of the reset timing setting capacitor 225 becomes higher than the voltage of the output terminal 1a of the AC adapter 1. At this time, the transistor 219 is turned on to short-circuit the terminals of the charge / discharge capacitor 205, and the charge / discharge capacitor 205 is always reset to a discharged state. Therefore, when the power plug 100 of the AC adapter 1 is reinserted into the power outlet or the AC power supply of the power outlet is restored, the charge / discharge capacitor 205 is always charged from the discharged state and the power supply control terminal 1b is initially controlled to L. Thus, the power source battery 31 of the battery unit 3 can be reliably charged with the DC power source of the power source voltage fed from the AC adapter 1 to the main unit 2, and when the main unit 2 is powered off, the AC adapter 1 Therefore, the power source battery 31 of the battery unit 3 can be reliably charged by the direct current power supplied to the main unit 2 from the main body device 2, and a power source device having a specific configuration can be provided.

  When charging of the power source battery 31 of the battery unit 3 is completed (time tz in FIG. 5), the transistor 214 is turned off, the discharge path 208 is ungrounded, and the terminal voltage of the charge / discharge capacitor 205 is changed to FIG. ) As shown by the solid line. When the terminal voltage of the charge / discharge capacitor 205 rises to the threshold voltage Vα, the power supply control terminal 1b of the AC adapter 1 becomes H, and the output terminal of the AC adapter 1 as shown by the solid line c in FIG. The voltage 1a drops from the power supply voltage (42V) to the idle voltage, and the reference voltage Vr of the reset timing setting capacitor 225 also drops from the specified voltage (20V) as shown by the solid line d in FIG. At this time, the reference voltage Vr does not exceed the voltage of the output terminal 1a of the AC adapter 1, and the transistor 219 is held off as shown in FIG. For this reason, if the power plug 100 of the AC adapter 1 is pulled out of the power outlet and re-inserted into the power outlet after the charging of the power battery 31 is completed, or if the AC power supply of the power outlet is momentarily stopped (momentary interruption), The charging / discharging capacitor 205 is not reset by discharge, but there is no inconvenience since the charging is completed.

  When the power supply battery 31 being charged is removed from the main unit 2 and remounted, the charging circuit 204 stops the charging process and turns off the transistor 214 by removing the time txx in FIG. At this time, the charge / discharge capacitor 205 is in a state where the negative electrode side (the other end side) is floated from the ground potential (more precisely, a potential (0.7 V) higher than the forward voltage of the diode 206). Therefore, the terminal voltage (positive voltage) on one end side changes as shown by a solid line g in FIG. 6B, and the negative voltage changes according to the positive voltage as shown by a solid line h in FIG. 6B. When the positive voltage rises to the threshold voltage Vα and the power supply control terminal 1b of the AC adapter 1 becomes H, the voltage at the output terminal 1a of the AC adapter 1 is the power supply as shown by the solid line e in FIG. The voltage (42V) drops to the idle voltage. The reference voltage Vr also decreases from the specified voltage (20V) as shown by the solid line f in FIG. Furthermore, due to the voltage drop at the output terminal 1a of the AC adapter 1, the positive and negative voltages of the charge / discharge capacitor 205 are also lowered as shown in FIG. 6B.

  When the battery unit 3 is reattached to the main unit 2 at time tyy in FIG. 6, the charging path of the power source battery 31 is regenerated, the charging circuit 204 restarts the charging process, and the transistor 214 is turned on. The discharge path 208 of the charge / discharge capacitor 205 is grounded. At this time, the negative electrode of the charging / discharging capacitor 205 is grounded via the charging path 207, and the charging / discharging capacitor 205 is clamped at 0.7V on the negative electrode side as shown in FIG. Lower. Therefore, the power supply control terminal 1b of the AC adapter 1 becomes L, and the power supply battery 31 of the battery unit 3 that has been reattached is charged by a DC power supply of the power supply voltage (42V) supplied from the AC adapter 1 to the main unit 2. can do. Note that when charging the power supply battery 31 of the reattached battery unit 3, the transistor 219 is held off as shown in FIG. 6C.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, the AC adapter 1 can be switched differently from the above-described embodiment. It may be a power supply configuration. Further, the battery unit 3 may have any configuration, and the power supply battery 31 may be any secondary battery. Further, the reset discharge means of the present invention may have a configuration different from that of the reset circuit 218, and the discharge path control semiconductor switch and the short-circuit semiconductor switch may be an FET or the like.

  Next, the power supply voltage, the threshold voltage Vα, the reference voltage Vr, the discharge time constant of the reset timing setting capacitor 225, and the like may be set appropriately according to design conditions and the like. It is not limited to.

  Moreover, when the main body device 2 is further reduced in size, the charging circuit 204 may be provided in the battery unit 3.

  The present invention can be applied to power supply devices for various electronic devices.

The connection diagram of one Embodiment of this invention. FIG. 2 is a detailed connection diagram of a part of FIG. 1. 2 is a timing chart for explaining operations when the reset circuit of FIG. 1 is not provided. FIG. 2 is a first timing chart for explaining the operation of FIG. 1. FIG. 3 is a second timing chart for explaining the operation of FIG. 1. FIG. 4 is a third timing chart for explaining the operation of FIG. 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... AC adapter, 1a ... Output terminal, 1b ... Power supply control terminal, 2 ... Main body apparatus, 3 ... Battery unit, 31 ... Battery for power supply, 125 ... Regulator part, 126 ... Output control part, 204 ... Charging circuit, 205 ... Charging / discharging capacitor, 207... Charging path, 208... Discharging path, 213... Transistor as first level holding means, 214... Transistor as discharge path control semiconductor switch of second level holding means, 218. Reset circuit, 219 ... transistor forming a short-circuiting semiconductor switch, 225 ... reset timing setting capacitor

Claims (3)

A DC power source of an AC adapter and a DC power source of a battery unit that is detachably attached to the main body device are supplied with power to the main body device with priority given to the power supply from the AC adapter, and the main device is in a power-off state A power supply device that charges a power source battery of a secondary battery configuration of the battery unit attached to the main body device with a DC power source of the AC adapter based on the charging control in
The AC adapter is
A regulator unit that converts an input AC power source into a DC power source and feeds the DC power source from the output terminal of the AC adapter to the main unit;
When the voltage of the output terminal is applied via a resistor and the main unit is in a power-on state and when the main unit is charged in the power-off state, the main unit is controlled to a low level. A power supply control terminal,
The voltage of the DC power supply of the regulator unit is controlled to the power supply voltage of the main unit by the low level of the power supply control terminal, and the voltage of the DC power supply of the regulator unit is idle lower than the power supply voltage by the high level of the power supply control terminal. An output control unit that controls the voltage,
The main unit is
When the AC adapter is connected with the battery unit mounted, one end is connected to the power supply control terminal, and the other end is grounded via the battery unit and the power supply control terminal is connected. A charge / discharge capacitor that is charged by the voltage of the output terminal and initially controls the power supply control terminal to a low level during charging from a discharged state;
First level holding means for grounding a discharge path drawn from one end of the charge / discharge capacitor in the power-on state and holding the power supply control terminal at a low level;
The AC adapter is activated by a DC power supply of the power supply voltage based on the initial control, and when the power supply battery is charged, the discharge path is grounded and the power supply control terminal is held at a low level. Second level holding means for returning the discharge path to non-ground due to loss of power supply of
A power supply apparatus comprising: a reset unit that short-circuits and discharges the charge / discharge capacitor to reset the charge / discharge capacitor to the discharged state due to a voltage drop of the output terminal based on the disappearance of power supply from the AC adapter. The second level holding means is
A power supply battery charging circuit that is activated by a DC power supply of the power supply voltage of the AC adapter and stops operation due to loss of power supply from the AC adapter;
A discharge path control semiconductor switch that is turned on by controlling the charging circuit to ground the discharge path when charging the power supply battery, and is turned off by stopping the operation of the charging circuit to return the discharge path to non-grounding; The power supply device according to claim 1, formed by: The reset means comprises:
When the DC voltage of the output terminal is charged to a reference voltage lower than the power supply voltage, and when the voltage of the output terminal drops below the reference voltage based on the disappearance of the power supply from the AC adapter, it is disconnected from the previous output terminal. A reset timing setting capacitor that discharges with a time constant set so that the terminal voltage drop is slower than the voltage drop of the output terminal;
3. The power supply device according to claim 1, wherein the power supply device is formed by a short-circuit semiconductor switch that is turned on when the terminal voltage becomes higher than the voltage of the output terminal to short-circuit between terminals of the charge / discharge capacitor.

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