JPH0591663A - Power supply controller and control method - Google Patents

Abstract

PURPOSE:To enhance reliability of device by sustaining the output voltage from a constant voltage power supply circuit at a constant level thereby guaranteeing normal operation of circuit to be operated at a constant voltage. CONSTITUTION:The power supply controller and control method for a device containing electronic circuits employing a constant voltage power supply circuit comprises a circuit 9 for turning ON/OFF power supply from a constant voltage power supply circuit 8 to a load, a circuit 4 for measuring the input voltage of the constant voltage power supply circuit, and a power supply control circuit 1 for turning the power supply ON/OFF circuit 9 OFF when the measured value of the voltage measuring circuit drops upto the lowest input voltage inherent to the constant voltage power supply circuit 8 and turns the power supply ON/OFF circuit ON upon recovery of the input voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply control device and a power supply control method in an apparatus including an electronic circuit using a constant voltage power supply circuit as a power supply.

[0002]

2. Description of the Related Art In order to keep an output voltage constant in a constant voltage power supply circuit, a minimum input voltage peculiar to the constant voltage power supply circuit is usually set. Conventionally, when the ON / OFF control of the power supply to the load by the constant voltage power supply circuit is performed, the power supply is simply started and stopped. However, in the case of a load having a large capacitance component, the power supply is started at the start of the power supply. Inrush current flows as a large charging current. Therefore, at the start of power supply, the input voltage is lower than the minimum input voltage specific to the constant voltage power supply circuit, so that the output voltage is low and the normal operation of the circuit cannot be guaranteed in many cases.

[0003]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to solve the conventional problem that the output voltage of the constant voltage power supply circuit decreases at the start of power supply, and normal operation of the circuit cannot be guaranteed. It is to solve.

[0004]

In order to solve the problems, the present invention starts supplying power to a load while measuring the input voltage of a constant voltage power supply circuit, and the input voltage is the minimum input voltage of the constant voltage power supply circuit. The power supply is stopped at the point when the input voltage has dropped, and the operation is restarted after a certain time when the input voltage recovers. This is done so that the input voltage does not drop below the minimum input voltage peculiar to the constant voltage power supply circuit, and the output voltage of the constant voltage power supply circuit is kept at a constant voltage.

[0005]

According to the present invention, even if a rush current as a large charging current flows at the start of power supply, as in the case of a load having a large capacitance component, ON / OFF control for the load is performed. By repeating this procedure, the charging of the capacitance component of the load is performed separately, and the input voltage does not drop below the minimum input voltage peculiar to the constant voltage power supply circuit. The output voltage of the voltage power supply circuit is maintained at a constant voltage, so that normal operation of the circuit that should be used at a constant voltage can be guaranteed, and the reliability of the device is enhanced.

Further, since the inrush current is divided by the ON / OFF control, the current supply capability of the non-constant voltage power supply unit such as an AC adapter for supplying power to the constant voltage power supply circuit may be small. This has the effect of reducing costs and reducing costs.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) Basic Configuration of Power Supply Control Device The basic configuration of a power supply control device of the present invention will be described below with reference to FIG. The voltage measuring circuit 4 constantly checks the input voltage of the constant voltage power supply circuit 8. The constant voltage power supply circuit 8 receives power from the non-constant voltage power supply unit 7 such as an AC adapter connected to a commercial power supply, and turns the power ON / OFF.
Power is supplied to the load 6 that consumes a relatively large amount of power via the circuit 9, and power is supplied to each circuit except the load 6 without the power ON / OFF circuit 9.

When power is supplied to the device, when the load is a load having a large capacitance component, for example, the voltage on the load side (load voltage) is low at first and the charging current for the capacitance component is large. The input voltage of the voltage power supply circuit 8 drops sharply. When the input voltage of the constant voltage power supply circuit 8 drops to the minimum input voltage, the voltage measuring circuit 4 operates in the power supply control circuit 1
The power supply control circuit 1 which has output the signal to the power supply control circuit 1 controls the power supply ON / OFF circuit 9 to turn it off, and controls the load 6 so that the constant voltage power supply circuit 8 does not supply power. The input voltage of the voltage power supply circuit 8 is restored, and when the input voltage is restored, the power supply ON / OFF circuit is turned ON, and this control is repeated thereafter.

(2) Application of Power Supply Control Device As an application example of the power supply control device, an example in which the device is applied to an image input processing device of a sewing machine will be described with reference to FIGS. 2 and 3.

The operation key 12 is operated to give various commands to the image input processing apparatus. The display device 13 performs various displays. The constant-voltage power supply circuit 18 receives power from a non-constant-voltage power supply unit 17 such as an AC adapter connected to a commercial power supply, and an image scanner 16 as a load that consumes a relatively large amount of power via a power ON / OFF circuit 19.
In addition to the power supply to the image scanner, power is supplied to each circuit such as the central processing unit 11 except the image scanner 16 without the power ON / OFF circuit 19.

The image data read by the image scanner 16 is temporarily stored in a storage device (not shown) of the central processing unit 11 and converted into embroidery data by a program stored in a built-in ROM (not shown). RAM card 1
Stored in 5.

When the power supply to the image scanner 16 is started from the point B in FIG. 3, the voltage (load voltage) on the image scanner side is low at first and the charging current for the electrostatic capacitance component is large. Input voltage is from B to C
As shown by the curve of, it drops sharply. At this time, the load voltage rapidly increases as shown by the curve from b to c.

The voltage measuring circuit 14 monitors the input voltage of the constant voltage power supply circuit 18 from the start of power supply, and as shown by C in FIG. 3, the input voltage reaches the minimum input voltage of the constant voltage power supply circuit 18. When it detects that it has dropped, it produces a signal. The central processing unit 11 inputs and recognizes the signal by interruption or the like, turns off the power ON / OFF circuit, and stops the power supply.

When the power supply is stopped, the load is reduced, so the input voltage rises as shown by the curves C to D in FIG. 3, and the load voltage changes from c to c because of the power consumption of the load. It gradually decreases as indicated by d.

The power supply is restarted at point D when a predetermined time has elapsed before the load voltage has completely dropped. Then, as the load voltage increased, the charging current also decreased, and the input voltage slowly decreased as shown by the curve from D to E,
The load voltage also slowly rises from d to e.

ON / OFF of the above power ON / OFF circuit 19
When the OFF control operation is repeated, the charging current for the capacitance component of the load becomes smaller and approaches a constant load current. (E to G, e to g)

When the load current becomes substantially constant and the input voltage does not drop to the minimum input voltage, power can be continuously supplied. Then (H to I), the load voltage rises until it becomes almost the same as the voltage of the power supply source as shown by the curve of h to i. However, due to the voltage drop of the power ON / OFF circuit 19, the resistance component of the wiring, and the like, a small potential difference may remain between the load voltage and the voltage of the supply source (input side of the power ON / OFF circuit).

The power ON / OFF circuit turns the load ON / O in response to the decrease in the input voltage of the constant voltage power supply circuit.
When the FF control is not performed, the input voltage of the constant voltage power supply circuit 18 interrupts the lowest input voltage as shown in FIG.
It is possible that the output voltage of the constant voltage power supply circuit 18 is also reduced in this state. When the output voltage of the constant voltage power supply circuit 18 drops, the central processing unit 1 may be used depending on the situation.
There is also a risk that the device will be reset without any guarantee that the device will operate normally.

[0019]

As described above, according to the present invention, even when a rush current as a large charging current may flow at the start of power supply, as in the case of a load having a large capacitance component, the load current may be increased. By repeatedly performing ON / OFF control, charging of the electrostatic capacitance component of the load is divided, and the input voltage does not drop below the minimum input voltage specific to the constant voltage power supply circuit. Therefore, the output voltage of the constant voltage power supply circuit is kept at a constant voltage, the normal operation of the circuit to be used at the constant voltage can be guaranteed, and the reliability of the device is enhanced.

Further, since the inrush current is divided by the ON / OFF control, the current supply capacity of the non-constant voltage power supply unit such as an AC adapter for supplying power to the constant voltage power supply circuit may be small. It is possible to reduce the price and the price.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a power supply control device.

FIG. 2 is a block diagram showing an example in which the power supply control device is applied to an image input processing device of a sewing machine.

[Fig. 3] Fig. 3 is a voltage waveform diagram for explaining control of a power supply when the remaining battery level is insufficient.

FIG. 4 is a voltage waveform diagram for explaining a case where the power supply is not controlled when the remaining battery level is insufficient.

[Explanation of symbols]

 1 power supply control circuit 11 central processing unit including power supply control circuit 4, 14 voltage measurement circuit 8, 18 constant voltage power supply circuit 6, 16 load circuit 9, 19 power supply ON / OFF circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Haruhiko Tanaka 3-1-1, Kyobashi, Chuo-ku, Tokyo Janome Sewing Machine Industry Co., Ltd.

Claims (2)

[Claims] 1. A device including an electronic circuit using a constant voltage power supply circuit as a power supply, a power supply ON / OFF circuit for turning on / off power supply to a load of the constant voltage power supply circuit, and an input voltage of the constant voltage power supply circuit. And a power supply ON / O circuit when a measured voltage value of the voltage measurement circuit drops to a minimum input voltage peculiar to the constant voltage power supply circuit.
A power supply control device comprising: a power supply control circuit that turns off the FF circuit and turns on after a fixed time when the lowered input voltage is recovered. 2. An apparatus including an electronic circuit using a constant voltage power supply circuit as a power supply, comprising a power supply ON / OFF circuit for turning ON / OFF power supply to a load of the constant voltage power supply circuit, and the constant voltage is measured by a voltage measuring circuit. The input voltage of the power supply circuit is measured, and when the measured value of the voltage measurement circuit drops to the minimum input voltage peculiar to the constant voltage power supply circuit, the power supply ON / OFF circuit is turned off via the power supply control circuit, and the voltage drops. A power supply control method, characterized in that control to turn on is repeatedly performed after a predetermined time when the input voltage recovers.