JPH10201122A - Charger for portable small equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a charging device for a portable small device, a range capable of simultaneously supplying a charging current to a secondary battery and an operating current of the device main body is widened. Reduce weight. SOLUTION: A small-size printer main body (device) is detected by a voltage detection circuit 12 whether or not the device is operating, and a current limiting circuit switching circuit 13 is operated in accordance with a state of the small-size printer main body 1 (device). Switching between the current for operating the main body 1 and the current for charging the secondary battery 3 is switched. As a result, the range in which the charging current and the operating current of the device can be supplied together is widened, and the problem that a large current that may occur in the early stage of charging the secondary battery 3 flows is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device for a portable small device such as a small printer having a built-in secondary battery.
In particular, the present invention relates to a technology for reducing the size of a small device.

[0002]

2. Description of the Related Art Conventionally, a portable small device such as a small printer has a secondary battery in a main body, and when an AC adapter is not connected, the operating power of the printer is supplied from the secondary battery, and an AC adapter is supplied. When is connected, the AC adapter supplies the operating power of the printer and also performs charging according to the charging capacity of the secondary battery.
At this time, only a rectified DC voltage is supplied from the AC adapter, and operating power is supplied to the printer,
The circuit constituting the charging means for charging the secondary battery has been built in the printer body.

[0003]

However, small printers are originally required to be portable, and despite the strong demand for miniaturization and weight reduction, when an AC adapter is used as described above, that is, If a circuit necessary only when the portable printer is not used is built in the main body of the small printer, there is a problem that the size and the weight are reduced. In addition, when the charging means is incorporated in the AC adapter, when a secondary battery having a low remaining capacity (low terminal voltage) is charged, a large current flows at the initial stage of charging so that the device is not damaged. It is necessary to provide current limiting means, and
It is necessary to preferentially allocate the current to the charging of the battery in consideration of the life of the battery, and for these reasons, there has been a problem that the current required for the operation of the printer main body cannot be supplied.

[0004] This point will be described with reference to FIG. 4 showing changes over time of the battery voltage and the charging current when the printer main body is connected to the charger. In FIG. 4, section A is a section in which the battery voltage is lower than a predetermined value, section B is a section after the battery voltage has reached a predetermined value by charging, section C is a section in which the battery has been charged, and ○ is the printer main body. Indicates that the operation of the printer is possible, and X indicates that the operation of the printer body is not possible.
In section A, if the charger limits the current with a charging current of 500 mA, the DC / DC
Current is consumed for the operation of the printer body after the voltage conversion circuit consisting of a converter, etc., and a satisfactory charging current does not flow to the battery, and sufficient current does not flow to the voltage conversion circuit.
Satisfactory operation cannot be performed. Further, assuming that the operating current of the printer is 300 mA,
The current required to charge the battery is 200 mA (500 mA-3
Until the current falls below 00 mA), a satisfactory charging current does not flow through the battery, and a sufficient current does not flow through the voltage conversion circuit, so that a satisfactory operation cannot be performed. There is a problem that a normal operation can be performed only in the section C.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is possible to simultaneously charge the rechargeable battery and the operating current of the device main body regardless of the remaining capacity of the rechargeable battery. It is an object of the present invention to provide a portable small-sized device charging device that can supply a wide range and can reduce the size and weight of the device body.

[0006]

According to the first aspect of the present invention, there is provided a charging device having a configuration separate from a portable small device main body, wherein a power supply state of the small device main body is provided. Power supply voltage detecting means for detecting a voltage, a constant voltage output means for outputting a constant voltage, and a small device main body operated by using the constant voltage output means as a power supply and / or charging a secondary battery built in the small device main body Output current limiting means for limiting the output current, and switching means for switching the limited current of the output current limiting means in accordance with the power supply state of the small device main body detected by the power supply voltage detecting means.

In the above configuration, the power supply voltage detecting means detects the power state of the main body of the small equipment, that is, whether the small equipment is in operation or not, and the switching means operates in accordance with the power supply state to output the output current. The limitation of the output current for operating the small device main body and / or charging the secondary battery by the limiting means is switched. For this reason, the range in which the current for charging the secondary battery and the current for operating the small device main body can be supplied together is widened, and a large current that can occur in the early stage of charging the secondary battery flows. There are no defects.

According to a second aspect of the present invention, in the charging device for a portable small device according to the first aspect, the switching means includes an optimal first current value to be limited for charging the secondary battery. And a second current value obtained by adding an average current value normally used by the small device main body to the first current value. In this configuration, in the initial stage of charging of a secondary battery having a low remaining capacity and a low terminal voltage, the current is limited to a first current value (constant current) to be optimally limited for charging, and a certain amount of charging is performed. When the terminal voltage reaches the specified voltage value, the current limit is switched to the second current value obtained by adding the average current value normally used by the small device main body to the first current value, and the device is switched together with the charging current. Supply operating current.

According to a third aspect of the present invention, in the charging device for a portable small device according to the first or second aspect, the secondary battery is a lithium ion battery. According to a fourth aspect of the present invention, in the charging device for a portable small device according to any one of the first to third aspects, a constant current constant voltage charging method is adopted. Claim 5
According to the present invention, in the charging device for a portable small device according to the first aspect, the output current limiting means limits the current at a specified limit current value when the switching means is switching to a larger limit current value. When the voltage falls below a specified value, the output is cut off. In this configuration, when the remaining capacity of the secondary battery is lost and the terminal voltage is greatly reduced, it is not necessary to perform a useless charging operation.

According to a sixth aspect of the present invention, in the charging device for a portable small device according to any one of the first to fifth aspects, the small device scans over the recording medium by scanning the recording medium. This is a small printer that performs printing.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a charging device for a small manual printer (portable small device) according to an embodiment of the present invention. FIG. 1 is an external view of a small printer main body and its charging device (AC adapter and charger). The small printer body 1 has a power switch 2 which is turned on by the user when using the printer, and has a built-in secondary battery 3 (lithium ion battery, nickel battery, etc.).
Can be used as a power source for portable use. The small printer body 1 is connected to a charger 5 constituting a charging device via a power supply line 4 as needed for charging a secondary battery and for printer operation, and the charger 5 is connected to an AC power supply. Connected to adapter 6.

FIG. 2 is a block diagram showing a circuit configuration of the main body of the small printer and its charging device. AC adapter 6
It includes an AC outlet 7 connected to an AC power supply (AC), a voltage conversion circuit 8 including a transformer, and a rectifier circuit 9.
The charger 5 employs a constant current constant voltage charging method.
A regulator circuit 10 (constant voltage output means), a current limiting circuit 11
(Output current control means), a voltage detection circuit 12 composed of a comparator or the like for detecting a power supply state of the small printer main body 1, and a limited current switching circuit 13 (switching means). In this charger 5, a voltage of 4.1 V passes through the regulator circuit 10.
Is supplied to the small printer main body 1 through the current limiting circuit 11 through the line 4a of the power supply line 4. The small printer main body 1 uses the power supplied from the line 4a of the power line 4 as a printer operating power, and / or
Or switching circuit 1 for switching for charging secondary battery 3
5. Voltage conversion circuit 16 including DC / DC converter
(Hereinafter referred to as a DC / DC converter), a control circuit 17 for controlling a printer operation, a drive circuit 18 for driving a print head 20, a liquid crystal display device 19, and a print head 2.
Contains 0. The DC / DC converter 16 is a power switch 2
Is turned on, the output is used as the operating power supply of the printer, and the voltage is supplied to the line 4b for detecting the power supply voltage.
The signal is transmitted to the voltage detection circuit 12 (power supply voltage detection means) of the charger 5 via the power supply line 4 (provided with the power supply line 4). FIG. 3 is a specific circuit diagram of the switching circuit 15, in which three diodes A,
B and C.

The operation of the small printer body having the above-described structure and the charging device thereof will be described below. When the charger 5 is connected to the small printer main body 1, the power supplied from the charger 5 via the line 4 a of the power supply line 4 is supplied to the DC / DC converter 16 via the backflow prevention diode A of the switching circuit 15.
Further, the power is supplied to the secondary battery 3 via the backflow prevention diode B, and the power from the secondary battery 3 is further supplied to the DC / DC converter 16 via the backflow prevention diode C. DC
The / DC converter 16 is connected to the power switch 2. When the power switch 2 is ON and the charger 5 is connected, the DC / DC converter 16 passes through the backflow prevention diode A or the backflow prevention diodes B and C. Converter 1
6, a voltage of 4.1 V from the line 4a of the power supply line 4 is input. When the charger 5 is not connected, DC
/ DC converter 16 has an output of 2.9V-
4. 1V to the circuit power supply voltage 5V and the printing head drive voltage 2
The voltage is converted to 4V and supplied to the control circuit 17 and the drive circuit 18, respectively.

Now, consider the case where the charger 5 connected to the AC is connected to the small printer main body 1 when the voltage of the secondary battery 3 is reduced to, for example, 3V. If the power switch 2 of the small printer body 1 is not turned on, the DC / DC converter 16 sets the output voltage to 0 V, so that no current flows through the DC / DC converter 16 and all the currents Used for charging the secondary battery 3. The voltage detection circuit 12 (comparator) in the charger 5 detects the voltage via the power supply voltage detection line 4b because the power supply voltage of the small printer main body 1 is 0 V, whereby the limiting current switching circuit 13 Current limiting circuit 1
1 is switched to the charging only mode, and the maximum current to be limited by the current limiting circuit 11 is set as the optimum charging current of the lithium ion secondary battery 3. Normally, lithium ion secondary battery 3
Is 1C. Now, assuming that the capacity of the lithium ion secondary battery 3 is 500 mAh, the current to be limited is 500 mA. As a result, FIG.
As shown in the figure, the lithium ion secondary battery 3 is 500 m
The constant current charging is performed by the current A (section A), and the current limiting circuit 11 limits the current with the current of 500 mA. Therefore, the output voltage of the charger 5 decreases, but does not decrease below the battery voltage. When the battery voltage reaches 4.1 V by continuing the charging operation, the current limit is released and the battery is charged at a constant voltage.

Next, if the power switch 2 of the small printer main body 1 is turned on, the voltage detection circuit 12 sends the DC / DC converter 1 via the power supply voltage detection line 4b.
6 is detected to be 5 V, and the limiting current switching circuit 13 is switched to the combined charging / operation mode. Now
Assuming that the input current to the DC / DC converter 6 is about 300 mA, the power consumption of the small printer main body 1 is 500 mA, so the current value to be limited is 800 mA. Since the current limiting circuit 11 limits the current at 800 mA, the output voltage of the charger 5 drops, but does not drop below the battery voltage. On average, 300 mA of the output current 800 mA of the charger 5 is D.
It flows to C / DC converter 16 and the remaining 500 mA is used to charge the battery. At this time, if the input voltage range of the DC / DC converter 16 is set to the minimum voltage of the battery, the operation of the device can be performed even if the voltage drops to the minimum voltage of the battery due to the charging operation of the battery. Even when the secondary battery is being charged with the optimum charging current, a current that can guarantee satisfactory operation can be supplied to the DC / DC converter 16 (section A).

The battery is charged and the voltage rises to 4.1V
, The current limit is released and constant voltage charging is performed, and the normal 4.1 V voltage is supplied to the DC / DC converter 16 (section B). At this time, the charging current of the battery is lower than 500 mA, but is 200 mA.
If this is the case, if the current limit is applied at 500 mA, a current sufficient for the operation of the small printer main body 1 cannot be supplied to the DC / DC converter 16, but the current limit value is 800 mA. Therefore, the device can be operated without any problem.

The present invention is not limited to the configuration of the above-described embodiment, but can be variously modified. For example, in the above-described embodiment, a small-sized printer is described as a portable small-sized device. However, the present invention can be applied to various types of devices that want to perform device operation while charging a battery. Further, in the above embodiment, a lithium-ion battery is taken as a secondary battery, but a Ni-based battery may be used. Further, although the constant current voltage charging method has been described as the charging method, a constant current pulse charging method may be employed. Further, the switching circuit may be an active switching circuit as long as it can be formed small and inexpensively.

[0018]

As described above, according to the portable small device charging apparatus according to the first aspect of the present invention, whether or not the small device main body is operating is detected based on the power state, and the power state is detected. The output current of the charger is switched according to the current, so that the range required to supply the current required to charge the secondary battery and the current required to operate the small device main body together is limited. Optimum charging can be performed in a short time without causing the problem that the current spreads and a large current that may occur at the initial stage of charging the secondary battery flows. Further, since the charging device separate from the small device is provided with a circuit configuration for switching the output current, the size and weight of the device main body can be reduced.

According to the second aspect of the present invention, the charging device is limited to an optimum charging current in the initial stage of charging according to the remaining capacity of the secondary battery, and the charging is advanced. At this point, the current limit is switched to a current obtained by adding the operating current of the small device main body to the charging current, so that the operating current of the device can be appropriately supplied together with the charging current.

According to the charging apparatus for portable small-sized equipment according to the third and fourth aspects of the present invention, the lithium ion secondary battery can be optimally charged by a constant current and constant voltage charging method.

According to the charging apparatus for a portable small device according to the fifth aspect of the present invention, when the remaining capacity of the secondary battery is in a state where it cannot be recharged, useless charging is performed. No action is required.

Further, according to the charging device for a portable small device according to the present invention, while charging the secondary battery,
The range in which the printing operation can be performed is widened, and a compact printer that is easy to use can be provided.

[Brief description of the drawings]

FIG. 1 is an external view of a small manual printer main body and a charging device thereof according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit configuration of a small printer main body and its charging device.

FIG. 3 is a specific circuit diagram of a switching circuit in the charging device.

FIG. 4 is a diagram showing changes over time of a battery voltage and a charging current when the printer main body is connected to a charging device.

[Description of Signs] 1 Small printer main body (small equipment main body) 3 Secondary battery 4b Line for power supply voltage detection (power supply voltage detection means) 5 Charger 6 AC adapter 10 Regulator circuit (constant voltage output means) 11 Current limiting circuit (Output current control means) 12 Voltage detection circuit 13 Limited current switching circuit (switching means)

Claims (6)

[Claims] 1. A charging device having a configuration separate from a portable small device body, comprising: a power supply voltage detecting means for detecting a power supply state of the small device body; and a constant voltage output means for outputting a constant voltage. An output current limiting means for limiting an output current for operating the small device main body using the constant voltage output device as a power supply and / or charging a secondary battery built in the small device main body; Switching means for switching the limiting current of the output current limiting means in accordance with the power supply state of the small equipment main body detected by the means. 2. The switching means adds a first current value to be limited optimally for charging a secondary battery and an average current value normally used by the small device main body to the first current value. The charging device for a portable small device according to claim 1, wherein the charging device switches between the second current value and the second current value. 3. The charging device for a portable small device according to claim 1, wherein the secondary battery is a lithium ion battery. 4. The charging device for a portable small device according to claim 1, wherein a constant current constant voltage charging system is adopted. 5. The output current limiting unit, when the switching unit switches to a larger limit current value, if the current is limited by a specified limit current value, the output current limit unit drops below a specified voltage value. The charging device for a portable small device according to claim 1, wherein the output is shut off. 6. The small printer according to claim 1, wherein the small device is a small printer that performs printing on the recording medium by scanning the recording medium. Charger for portable small equipment.