JPH05207669A - Power source circuit - Google Patents

Abstract

PURPOSE:To eliminate the heat generation of an entire apparatus by an external power source and to save power by deciding whether the charging of a battery by the power source is completed or not, and executing an automatic power turning-off function of the power source if the charging is completed. CONSTITUTION:Resistors R1, R2 are divided resistors for sensing presence or absence of connection of an external power source. A signal line L1 led by the divided resistor is connected to a detector 2, and an output line L2 of the detector 2 is connected to a central processing unit 6. When the power source is connected to a power jack PJ1, a signal level on the line L1 is raised by a certain potential by the resistors R1, R2. Whether an inner battery BAT is fully charged or not is monitored by divided resistors R4, R5 and a transistor TR. If the battery BAT is fully charged, the transistor TR is turned ON by the resistors R4, R5. The unit 6 starts an automatic power turning-off function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit which has an automatic power-off function and shuts off the power supply of a built-in battery even when the key input device is not used for a certain period of time.

[0002]

2. Description of the Related Art Conventionally, in electronic equipment having a built-in chargeable / dischargeable battery, it is determined whether the power supply currently being supplied is an external power supply or a built-in battery, and if the latter built-in battery is used, a fixed time is required. Some have an auto power-off function that shuts off the power after a certain time only when there is no key input.

[0003]

However, in the example described above, when the built-in battery is used, the power is cut off after a certain period of time when there is no key input for a certain period of time.
It had the following drawbacks.

(1) Since the built-in battery is charged when the external power supply is used, the auto power-off function is not activated, and the external power supply is not shut off even after the built-in battery is charged, and there is no power saving effect.

(2) In laptop type and notebook type electronic devices equipped with a liquid crystal display, long-time energization caused by the use of an external power source causes heat generation in each element, causing deterioration of the electronic device.

Further, in the above-mentioned conventional example, since the auto power off is executed regardless of the battery capacity, there is another drawback as follows.

(1) Since the auto power off is constant, the battery is consumed quickly and the battery drive time is shortened.

(2) No further power saving effect can be obtained.

In view of the above points, the first object of the present invention is to provide a power supply circuit capable of performing the auto power-off function except when the charge / discharge battery is being charged.

A second object of the present invention is to provide a power source which can suppress power consumption for the auto power off function as much as possible.

[0011]

In order to achieve such an object, a first invention is to supply power from a chargeable / dischargeable battery, charge the battery with an external power source, and during the charging. In a power supply circuit capable of supplying power from the external power supply and capable of executing an auto power-off function for the battery, a determining unit that determines whether or not charging of the battery by the external power supply is completed. When the result of the determination is that the charging is completed, the first control means for instructing the external power source to execute the automatic power off function is provided.

A second aspect of the present invention is a power supply circuit capable of executing an automatic power-off function of supplying power from a battery to an electric circuit and stopping the supply of the power when the electric circuit is not in use for a certain period of time. A detection means for detecting the capacity of the battery according to the voltage or the current of the battery, and a second control means for variably setting the fixed time counted in the auto power-off function in correspondence with the detected capacity. It is characterized by having

[0013]

In the first aspect of the invention, when the battery is completely charged, the auto power off function is executed, and when the apparatus is not in use for a certain period of time, the power supply of the external power source is also stopped. In the second aspect of the invention, the smaller the battery capacity, the shorter the time until power off and the smaller the power consumption until power off.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings.

<First Embodiment> FIGS. 1 and 2 show a first embodiment of the present invention, each of which comprises a circuit diagram and a flow chart.

In FIG. 1, reference numeral 1 is a power jack of an external terminal for connecting an external power source, and resistors R1 and R2 are dividing resistors for detecting the presence or absence of the external power source connection. The signal line L1 drawn from the dividing resistor is connected to the detection circuit 2,
The output line L2 of the detection circuit 2 is connected to the central processing unit 6. If the level of the signal line L2 is logic "0", the external power supply is connected, and if the level is logic "1", only the internal battery BAT is driven (external power supply not connected). The detection circuit 2 generates a signal of logic "0" when the voltage of the signal line L1 is higher than the threshold value, and generates a signal of logic "1" in the opposite case.

The power supply line L3 passes through the diode D1, is connected to the charge / discharge battery BAT via the charging resistor R3, and is also supplied to the power supply unit 3.

The power supply unit 3 supplies various kinds of power to the system, and the power supply line L4 is represented as a representative in this drawing.

The signal line L5 is a central processing unit (CPU)
The signal line received from 6 stops the function of the power supply unit 3 at logic "0".

The resistors R4 and R5 are division resistors set to switch the transistor TR.

The central processing unit 6 controls the shutoff of the power supply unit 3 based on the above detection signal under a predetermined condition.

A subtraction counter is used as the timer 7, and measures the time for starting the automatic power off.

Next, the operation of this circuit will be described.

Now, assuming that no external power supply is connected to the power jack PJ, the power supply line L3 is in an open state. Therefore, the output signal line L2 of the detection circuit 2 becomes a logic "1" and informs the central processing unit 6 that it is a drive signal from the built-in battery BTA.

The built-in battery BAT supplies power to the power supply section 3 through the diode D2, whereby various power supplies are generated here and transmitted to the system through the power supply line L4.

When the central processing unit 6 determines from the timer 7 that there is no key input for a certain period of time, it shuts off the power (auto power off). For this purpose, a cutoff instruction signal is sent to the power supply unit 3 via the signal line L5.

In response to this, the power supply unit 3 stops the power transmission of the power supply line L4 which distributes the power to the system.

Now, assuming that an external power supply is connected to the power jack PJ, the signal level on the signal line L1 is raised to a certain potential by the dividing resistors R1 and R2.

As a result, the output line L2 of the detection circuit 2 becomes logic "0", and the central processing unit 6 is informed that the drive is from an external power source.

The central processing unit 6 monitors the signal level of the signal line L6 while executing the above control.

This signal indicates the charging state when the built-in battery BAT is charged from the outside via the charging resistor R3.

That is, whether or not the built-in battery BAT is in a fully charged state (charging completed) is monitored by the dividing resistors R4 and R5 and the transistor TR. More specifically, battery B
When the AT is fully charged, the transistor TR is turned on (active) by the dividing resistors R4 and R5 programmed in advance by hardware. Therefore, the transistor TR operates as the determination means of the first invention.

Therefore, when power is supplied from the external power source and the charging of the internal battery BAT is completed, the transistor TR is turned on (ON), and the signal on the signal line L6 becomes a logic "0".

When these two states (external power supply connection, built-in battery BAT is fully charged) are detected, the central processing unit 6 activates the auto power off function, and if there is no input to the key for a certain period of time. If judged, on the signal line L5,
An active signal is sent to stop the operation of the power supply unit 3.

At this time, the central processing unit 6 operates as the first control means of the first invention.

FIG. 2 is a flow chart showing the control processing of the central processing unit 6 described above.

In FIG. 2, in step S1, the central processing unit 6 determines whether or not the external power supply is connected by the detection signal of the detection circuit 2.

If the signal on the signal line L2 is logic "1", jump to step S3. If not, go to step S2.

The state where the built-in battery BAT is charged by the external power source is monitored by the dividing resistors R4 and R5 and the trunk transistor TR.

Since the charging content is sent to the central processing unit 6 via the signal line L6, the central processing unit 6 determines whether or not it is in the fully charged state by the signal of the signal line L6 in step S2.

If not fully charged, step S2 is looped to wait for the built-in battery BAT to be charged. Therefore, at this time, the auto power off function is not activated.

After detecting that the built-in battery BAT has reached full charge, the procedure proceeds to step S3.

In step S3, the automatic power-off function is activated, and more specifically, a specific value is set in the subtraction counter and subtraction is performed.

In step S4, it is determined whether or not the numerical value of the subtraction counter is zero, and if the numerical value is zero, that is, a predetermined time has elapsed, the process proceeds to step S6, the function of the power supply unit 3 is stopped, and this procedure is ended. To do.

If the value of the subtraction counter is not zero, the process proceeds to step S5, and the value of 1 is subtracted from the content of the subtraction counter.

After that, the process jumps to step S4, and the numerical value judgment process of the subtraction counter is performed.

In the circuit of FIG. 1, the fully charged state is detected by the transistor TR, but a circuit using a comparator is shown in FIG.

It should be noted that the numbers that overlap in FIG. 3 and FIG. 1 indicate the same or corresponding parts.

Assuming that the external power supply is not connected, the internal battery BTA is connected to the power supply unit 3 via the diode D2.
Power is being supplied to. On the other hand, this power supply is
6, divided by R7 and connected to the input of the comparator 4. For this input, the constants of the dividing resistors R6 and R7 are selected so that the reference voltage of the comparator 4 matches the voltage when the built-in battery BAT is fully charged.

As described in FIG. 1, the power supply unit 3 has
It is a power generation unit for sending electric power to the system, and is transmitted from the power line L4.

Next, assuming that an external power source is connected to the power jack 1, the power source is charged into the rechargeable battery BAT through the diode D1 and the charging resistor R3.

At the same time, the power is also supplied to the power supply unit 3 and, like the previous driving of the battery BAT, the power required for the system is generated here and is transmitted through the power supply line L4.

When the charge state of the rechargeable battery BAT is low, the input signal L7 of the comparator 4 does not reach the reference voltage, so the signal of the output signal line L6 does not become logic "0" (active state) but logic "1". Remains maintained.
When the rechargeable battery BAT is fully charged at a certain point, the signal levels of the signal line L7 match the reference voltage of the comparator 4 by the dividing resistors R6 and R7, and the signal of the signal line L6 becomes logic "0".

Two states (external power source is connected,
When the rechargeable battery BAT is fully charged), the central processing unit 6 then controls the signal line L5 to automatically power off after confirming that the key has not been input for a certain period of time. Then, the operation of the power supply unit 3 is stopped.

FIG. 4 shows an example in which the current detection circuit detects the fully charged state.

In FIG. 4, the external power source is the power jack 1.
Is connected to the diode D1
And is supplied to the power supply unit 3. The power supply unit 3 generates a necessary power supply to be supplied to the system (not shown) and transmits the power via the power supply line L4. In addition, the power supplied through the diode D1 is charged by the charging resistor R to charge the charging battery BAT.
Charge via 3 and R8.

The current detector 5 for detecting the state of charge of the rechargeable battery BAT monitors the current flowing across the resistor R8. That is, when the capacity of the rechargeable battery BAT is low, the resistance R
A large amount of current flows through the battery 8, and conversely, when the battery is in a state of being almost fully charged, the terminal voltage of the rechargeable battery BAT increases and the current decreases.

Utilizing this, when the current detector 5 determines that the rechargeable battery BAT is fully charged, it sets the logic "0" of the signal line L6 and informs the central processing unit 6.

When the central processing unit 6 receives this signal and determines that there is no input to the key for a certain period of time, it sends an active signal onto the signal line L5 to stop the function of the power supply unit 3 (auto power off). Let

As described above, in the first embodiment, the automatic power-off function is not executed until the external power source charges the battery until it reaches the full charge (charge completed state), and in other cases. Executes the auto power off function.

Therefore, when the external power source is connected for a long time as in the conventional case, the internal circuit is not damaged by the heat generation of the entire device, and the power saving is achieved.

<Second Embodiment> FIGS. 5 to 6 show a second embodiment of the present invention, each of which comprises a circuit diagram and a flow chart.

In FIG. 5, reference numeral 21 is an external terminal power jack for connecting an external power source. The power line L21 passes through the diode D21 and the charging / discharging battery B through the charging resistor R1.
It is connected to the AT and is also connected to the power supply unit 22.

The power supply unit 22 supplies various power supplies to the system. In the drawing, the power supply line L22 is representatively shown.

The signal line L23 is a central processing unit (CP
U) 25 is a signal line for writing numerical data to the timer 26.

The signal line L24 is an output signal line from the timer 26, and this signal causes the central processing unit 25 to stop the function of the power supply section 22 via the control signal line L28 to automatically turn off the power.

The battery BAT supplies power to the power supply section 22 through the diode D22 when the external power supply is not connected to the power jack 21.

The anode of the battery BAT is the voltage detector 23.
And 24 inputs. Voltage detector 23,
The output signal lines L25 and L26 of 24 are connected to the central processing unit 2
Connected to 5. Also, 27 is a keyboard.

When the input voltage is the charging voltage V1 which is higher than the voltage BAT, the voltage detector 23 outputs "1" as the output signal L25 when "0" is reversed. The voltage detector 24 outputs "0" to the output signal line L26 when the input voltage is higher than the first threshold voltage V2 (<V1) and "1" in the opposite case.

The operation of such a circuit will be described.

Now, assuming that an external power source is connected to the power jack 21, the power source of the power source line L21 is supplied to the power source section 22 through the diode D21 and also to the rechargeable battery BAT through the charging resistor R1. (Charged).

The power supply unit 22 supplies various power supplies to the arithmetic processing unit 25, the keyboard 27, and other devices (not shown). In the figure, the power supply line L22 is shown as a representative thereof.

In such a state, since the input voltage of the power supply unit 22 is V1, the voltage detector 23 outputs a detection signal of "0" and the voltage detector 24 outputs a detection signal of "0".

The central processing unit 25 detects that charging is in progress based on the levels of these detection signals, and does not execute the auto power off function.

On the other hand, there is no external power source, and the charge / discharge battery BAT
When the threshold voltage V2 or more is supplied, the central processing unit 25 is detected based on the detection signals of the voltage detectors 23 and 24.
Writes the numerical value of the time T1 to the timer 26 via the signal line L3. The timer 26 starts subtraction at the same time as reading the numerical data. When the timer 26 has finished counting to zero, the central processing unit 25 is notified of the end of counting via the signal line L4.

Then, the central processing unit 25 determines that the timer 2
During the subtraction of 6, whether or not a key (not shown) on the keyboard 27 is registered is checked through the signal line L27.

If the number has been entered, the central processing unit 25 sets the value of the time T1 again in the timer 26 through the signal line L23.

On the contrary, if not registered, the central processing unit 25 sends an active signal to the control signal line L28 to stop the function of the power supply unit 22. That is, the power is automatically turned off.

Next, assuming that the capacity of the battery BAT, more specifically, the input voltage V decreases from the threshold voltage V2, the change (V1>V2> V) is detected by the voltage detectors 23 and 24, Notify the central processing unit 25. The central processing unit 25 sets the time T2 (T2 <T1) to the timer 26 via the signal line L23 as in the above.

The timer 26 performs the subtraction, and when it becomes zero, it notifies the central processing unit 25 of a signal to that effect through the signal line L24.

In response, if the central processing unit 25 can confirm from the signal line L27 that there is no register from the keyboard 27 during the subtraction of the timer 26, the control signal line L2
By stopping the function of the power supply unit 22 through 8, automatic power off is realized.

FIG. 6 shows a processing procedure of the central processing unit 25 related to the above-mentioned operation.

In FIG. 6, since the voltage detecting circuits 23 and 24 monitor the consumption state of the battery BAT,
If the battery BAT capacity is sufficient without an external power source, the signal on the signal line L25 is "1" and the signal on the signal line L26 is "0". When the battery capacity level is confirmed by this signal, the central processing unit 25 sets the numerical value T1 in the timer 26 (steps S21 → S22), jumps to step S25, and executes the auto power off function.

On the other hand, when the central processing unit 25 identifies that the battery BAT capacity is insufficient without the external power supply, T2 is selected as the set value of the timer 26 (steps S21 → S23 → S24). ..

Thereafter, in step S25, the auto power off function is activated. More specifically, steps S25 to S
The set time is measured by the loop processing of 26, and after the time measurement, when there is no key input, the power supply unit is shut off (step S26 →
S27 → S28).

When the external power supply is connected, the output signals of the voltage detectors 23 and 24 are both "0", and S in FIG.
Negative determinations are obtained in both the determination processes of 21 and S22.

Therefore, in FIG. 6, the execution procedure of the central processing unit 25 proceeds in the order of steps S21 → S23 → end, and the auto power off function is not executed.

In the second embodiment, the capacity of the charge / discharge battery BAT is detected by the voltage, but it goes without saying that the present invention can be implemented by detecting the current.

In addition, in the second embodiment, a chargeable / dischargeable battery has been described, but a non-chargeable battery such as a dry battery may be used.

[0090]

As described above, according to the first aspect of the invention, the automatic power-off function is not executed while the battery is being charged, and the charging process is not blocked. Further, since the auto power-off function is executed after the completion of charging, the entire device does not generate heat due to the external power source, and power saving is achieved.

In the second aspect of the invention, by controlling the auto power-off time according to the battery capacity state, there is an effect of saving power, further suppressing the battery consumption of the electronic device as much as possible, and extending the battery drive time.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a first embodiment of the present invention.

FIG. 2 is a flowchart showing a control processing procedure executed by a CPU 6 of FIG.

FIG. 3 is a circuit diagram showing another circuit configuration of the first embodiment.

FIG. 4 is a circuit diagram showing another circuit configuration of the first embodiment.

FIG. 5 is a block diagram showing a circuit configuration of a second embodiment of the present invention.

6 is a flowchart showing a control processing procedure of a CPU 25 of FIG.

[Explanation of symbols]

 1 Power Jack for External Power Supply Connection 2, 23, 24 Voltage Detector (Detection Circuit) 3 Power Supply Section 5 Current Detection Circuit (Current Detection Section) 6, 25 Central Processing Unit (CPU) 7, 21 Timer (Subtraction Counter) BAT Chargeable / dischargeable batteries D1, D2, D21, D22 Diodes R1 to R8, R21 Resistance

Claims (2)

[Claims] 1. A power source is supplied from a chargeable / dischargeable battery, the battery is charged by an external power source, and during the charging,
A power supply circuit capable of supplying power from the external power supply and capable of executing an auto power-off function for the battery, and a determining unit for determining whether or not charging of the battery by the external power supply is completed. A power supply circuit comprising: first control means for instructing the external power supply to execute the automatic power-off function when the result of the determination is that charging is completed. 2. A power supply circuit capable of executing an automatic power-off function of supplying power from a battery to an electric circuit and stopping the supply of the power when the electric circuit is not in use for a certain period of time. It is provided with a detection means for detecting the capacity of the battery by voltage or current, and a second control means for variably setting the fixed time measured by the auto power-off function in correspondence with the detected capacity. Characteristic power supply circuit.