KR100623702B1 - Hand-Held Device for controlling Operation of Power Source according to humidity - Google Patents

Abstract

Disclosed is a portable electronic device that blocks operation of an internal power supply according to an increase in moisture or moisture. In order to prevent the internal functional blocks from being destroyed or malfunction due to excessive moisture or immersion, the portable electronic device includes a humidity sensor and is configured to block the power supply operation when a predetermined reference value is exceeded.

Description

Hand-Held Device for controlling Operation of Power Source according to humidity

1 is a block diagram illustrating a portable electronic device according to a preferred embodiment of the present invention.

2 is a characteristic view for explaining the operation of the resistance-type humidity sensor according to an embodiment of the present invention.

3 is a characteristic diagram illustrating the operation of the capacitive humidity sensor according to the preferred embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: humidity sensor 110: voltage converter

120: comparison unit 130: power control unit

140: power supply

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable electronic device, and more particularly, to a portable electronic device having a function for preventing the internal circuit caused by excessive moisture or moisture from being destroyed.

The portable electronic device uses various kinds of internal power sources, which are generated and controlled by a power generation circuit provided inside the portable electronic device. The power generation circuit of the portable electronic device receives power from a secondary battery, commonly referred to as a battery. Secondary batteries have the property of being recharged and reusable even though the charged electrical energy is consumed. There are two types of secondary batteries, which include nickel cadmium (NiCd) batteries and batteries using lithium.

Nickel cadmium batteries, which have been used conventionally, have a feature of charging with a constant current. Nickel cadmium batteries undergo chemical reactions at the positive and negative electrodes during charging and discharging to change active materials. When overcharged, water decomposes, but when the negative electrode active material is more than the positive electrode active material, only oxygen gas is generated at the positive electrode and absorbed at the negative electrode. At this time, a drop in battery voltage occurs and full charge is possible by detecting this.

In contrast, in lithium ion batteries, movable ions travel between the positive electrode and the negative electrode during charging and discharging, and electrical energy is generated by a redox reaction. When the battery voltage rises after full charge, the solvent starts to decompose instead of water, but it is impossible to design a battery that absorbs the decomposed gas such as nickel cadmium battery. It is necessary not to.

Lithium ion batteries use a carbon material reversibly inserting lithium ions as a negative electrode active material, and a lithium transition metal oxide as a positive electrode active material.

Lithium polymer batteries use lithium alloy as a negative electrode active material and SPE (Solid Polymer Electrolyte) as an electrolyte.

In the case of a lithium ion battery, since the constant voltage charging method is used, the voltage is determined to be an absolute value. Usually, the charge control voltage employs two types of control voltages, 4.1V / cell and 4.2V / cell. The accuracy in the case of measuring the voltage relatively is only a minimum resolution, and the difference by the quantity of batteries connected in series is not a problem. In the case of absolute measurements, however, both measurement range and minimum resolution are problematic. Therefore, the charge control circuit of the lithium ion battery requires a high-precision constant voltage circuit corresponding to the battery voltage.

In general, a lithium ion battery is charged with a constant current until the battery voltage becomes 4.1V or 4.2V, and when this voltage is reached, the battery is switched to the constant voltage method and charged with a small value of 50 mA to 100 mA.

There are three types of charging methods for the lithium ion battery and the lithium polymer battery.

First, the step-down method, characterized in that the input voltage is higher than the output voltage.

The second is a step up and down method, where the input voltage may be higher or lower than the output voltage.

Thirdly, the step-up method is characterized in that the input voltage is lower than the output voltage.

In general, a step down method is used, and the step down method is divided into a pulse width modulation (PWM) and a linear method. In the PWM method, the control element changes the duty ratio of the transistor or the FET of the switching unit at a predetermined frequency, and controls the output voltage and the output current. The linear method is controlled by the output of the comparator inside the control unit regardless of the fixed frequency. It is a method of controlling transistors or FETs.

Charging in this step-down method is measured by the open circuit voltage of the battery before charging is made. When the open circuit voltage of the battery is measured and this voltage is about 2V or more, the charging circuit is activated and fast charging occurs.

Recently, the use of lithium secondary batteries, cell phones, mp3, pda, etc. have been demanding long-term use with a single charge.

In addition, the above-described secondary batteries have an overcurrent or overdischarge protection circuit therein. The sensor detects an amount of current flowing into the internal functional blocks of the portable electronic device from the secondary battery and internally blocks the current path of the secondary battery.

However, when the portable electronic device is exposed to excessive humidity or inundation during use of the portable electronic device, an overcurrent or overdischarge protection circuit may operate only when an overcurrent is supplied into the portable electronic device. That is, a plurality of functional blocks therein are damaged by overcurrent or overdischarge, and have to be in an unrecoverable state, so that a protection circuit operates to cut off power drawn from the secondary battery.

 SUMMARY OF THE INVENTION An object of the present invention for solving the above problems is to provide a portable electronic device that includes a humidity sensor or the like, when the reference humidity exceeds the reference humidity, internally blocking the power flowing from the secondary battery.

The present invention for achieving the above object, the humidity sensor for sensing the humidity or moisture of the external environment; A voltage converter configured to convert the current amount of the humidity sensor into a voltage signal; A comparison unit for generating a flag signal by comparing a voltage signal of the voltage conversion unit with a reference signal; And a power controller configured to control power according to a flag signal of the comparator.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Example

1 is a block diagram illustrating a portable electronic device according to a preferred embodiment of the present invention.

Referring to FIG. 1, the portable electronic device according to the present exemplary embodiment includes a humidity sensor 100, a voltage converter 110, a comparator 120, a power controller 130, and a power supply 140.

The humidity sensor 100 is a sensor that detects humidity in the air by color change, ion amount change, electromotive force / current change, etc. due to a chemical reaction. The humidity sensor 100 is used to change the electrical properties of the polymer material by the adsorption or desorption of water, there is a resistance type for detecting a change in electrical resistance and a capacitance type for detecting a change in capacitance.

Therefore, in the resistive humidity sensor, the change in humidity is represented by the change in resistance, and in the capacitive humidity sensor, the change in humidity is represented by the change in capacitance.

The voltage converter 110 converts a change in resistance or a change in capacitance in the humidity sensor 100 into a predetermined voltage. In the case of a resistive humidity sensor whose resistance changes, when a predetermined constant current is applied to the sensor, the change in resistance is detected as a change in voltage. In addition, in the case of a capacitive humidity sensor having a change in capacitance, a change in humidity may be recognized by applying a predetermined constant current and sensing a rising ratio of voltage.

In addition, the comparator 120 compares the voltage signal generated by the voltage converter and the reference voltage Vref having the information on the reference humidity with the information on the humidity. When the voltage signal exceeds the reference voltage Vref by the comparison operation, the comparison unit 120 generates a flag signal. The reference voltage may be supplied by a central processing unit or a processor (not shown) provided in the portable electronic device. In addition, the reference voltage Vref is the amount of humidity that the portable electronic device can accept for normal operation.

Typically, when the relative humidity is 100%, it refers to the maximum amount of moisture that air can contain at the current temperature. That is, when the relative humidity is 100%, water vapor in the air starts to condense and begins to form water droplets. Therefore, the portable electronic device is guaranteed the product reliability at 90% to 95%, but the product reliability is not guaranteed at higher humidity, so the reference value of relative humidity is preferably 90% to 95%.

The power control unit 130 receives the flag signal generated from the comparator 120 and blocks the operation of the power supply unit 140 according to the received flag signal.

It is preferable that the operation of the power supply unit 140 cut off the power of the secondary battery received from the adapter by controlling a switch inside the power supply unit 140. As described above, when a relative humidity of a predetermined reference value or more is detected, the internal circuits may be protected by cutting off the power of the power supply unit 140 inside the portable electronic device.

2 is a characteristic view for explaining the operation of the resistance-type humidity sensor according to an embodiment of the present invention.

Referring to FIG. 2, the resistance type humidity sensor decreases electrical resistance as humidity increases. That is, when the relative humidity is low, the resistance has a very high value, and as the relative humidity increases, the resistance is kept low.

3 is a characteristic diagram illustrating the operation of the capacitive humidity sensor according to the preferred embodiment of the present invention.

Referring to FIG. 3, the capacitance of the capacitive humidity sensor has a characteristic proportional to the relative humidity. In addition, the capacitive humidity sensor uses a hydrophilic polymer-sensitive material such as cellulose acetate or cellulose lactate.

That is, the dielectric constant of the polymer is increased according to the adsorption of water, and an electrode is installed on the polymer to detect the change in capacity.

According to the above-described embodiment, when the predetermined reference humidity is exceeded, an internal power control circuit may operate to cut off power of the power supply unit provided in the portable electronic device. Therefore, the power supply can be shut off before overcurrent or overdischarge occurs, thereby preventing the portable electronic device from being damaged by immersion or excessive moisture.

According to the present invention as described above, it is possible to prevent the malfunction or malfunction of the portable electronic device due to the increase in humidity or flooding.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (7)

A humidity sensor for sensing humidity or moisture in an external environment; A voltage converter configured to convert the current amount of the humidity sensor into a voltage signal; A comparison unit for generating a flag signal by comparing a voltage signal of the voltage conversion unit with a reference signal; And And a power controller for controlling power according to a flag signal of the comparator. The portable electronic device of claim 1, wherein the humidity sensor is a resistive humidity sensor or a capacitive humidity sensor. The portable electronic device of claim 2, wherein the resistance type humidity sensor has a resistance value that decreases as the relative humidity increases. The portable electronic device of claim 3, wherein the capacitance-type humidity sensor increases in capacitance as the relative humidity increases. 5. The portable electronic device according to claim 4, wherein the capacitive humidity sensor is a hydrophilic polymer moisture sensitive material having cellulose acetate or cellulose lactate. The portable electronic device of claim 5, wherein the reference signal has a voltage level corresponding to a relative humidity of 90% to 95%. The portable electronic device of claim 1, wherein the power control unit blocks the generation of the power by receiving the flag signal.

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