text: 1. Field of Invention
  The present invention relates to a warmer device, and more particularly to a warmer device and operating method thereof, wherein the warmer device comprises a protection device, a rechargeable warmer bag, and a monitoring device, wherein the rechargeable warmer bag comprises a bag, a heating unit, a charging unit and the monitoring device is arranged in the protection device with respect to the rechargeable warmer bag so that the rechargeable warmer bag is monitored and control by the monitoring device while the rechargeable warmer bag is being charged in the cavity of the protection device. Therefore, when the rechargeable warmer bag is heated to be over expanded, the monitoring device cuts the power supply of charging unit of the rechargeable warmer bag. However, when the rechargeable warmer bag is being used, the rechargeable warmer bag and the monitoring device are separated.
  2. Description of Related Arts
  During winter time, most people would like to use some warmer apparatus, such as electric heaters, in order to keep themselves warm. However, such warmer apparatus requires an electric power and has a relatively bulky size that the user cannot carry the warmer apparatus everywhere.
  As everyone knows, it is very cold in winter, so people have invented various kinds of warmer device to keep warm in cold days. Some kinds of warmer device are huge, and inconvenient to carry out.
  There is a kind of small and portable warmer device, called warm water bag comprising a bag and a sealing cover, wherein the bag is made of water proof material such as plastic. The bag has an inner cavity and an opening, and the sealing cover is to cover the opening. In order to use it, the user has to heat a certain amount of liquid, such as water in a stove or other devices, and fill the warm liquid into the inner cavity of the bag. At last, cover the sealing cover onto the opening to seal the cavity so as to keep the liquid inside. Therefore, the user is able to hold the bag close to the body of the user. In other words, the water inside the cavity gradually dispenses its heat through the sealing bag, so that the user can put the bag to part of body, such as hands or feet, to keep himself or herself warm.
  The warm water inside the cavity conducts or radiate the heat to the outside constantly, so that the user can put the warm water bag to part of body where is cold, such as hands or feet to keep warm.
  However, an essential disadvantage of the traditional warm water bag is inconvenient to use. Since the liquid radiate its heat, the temperature is decreasing at the same time. The warm water bag can no longer provide heat when the temperature drops down to a level similar to the body temperature. The user has to pour out the liquid in the cavity and refill warm water repeatedly. It is very inefficient and inconvenient.
  Some inventors create a kind of rechargeable warmer bag, comprising a bag, a power supply unit, and a warmer device, wherein the bag has a cavity with a predetermined amount of liquid therein and the warmer device which is positioned in the cavity of the bag comprises a heating tube and a socket connecting to the power supply unit.
  In order to use the rechargeable warmer bag, connect it to the power supply, so that the electricity is converted to heat in the heating tube and the heating tube conducts heat to the liquid in the cavity. After a certain time, the liquid is warm enough, the user cuts off the power supply to use the rechargeable warmer bag.
  But, as mentioned above, the liquid in the cavity will expand when the rechargeable warmer bag is being charged. The higher the temperature, the more it expands. When it expands too much, the pressure in the bag is rising. As the pressure is rising to a certain extent, the bag will be broken and the hot liquid inside will be leaked or even sprayed out. If this is happened, the conventional rechargeable warmer bag contains safety problems and causes dangerous to the user's life. This is a main disadvantage of the rechargeable warmer bag.
  An improved water bag is made that the water bag is adapted to be placed in a microwave oven to heat up the water inside the water bag. Likewise, a built-in heating element is mounted into the water bag to heat up the water inside the water bag.
  However, the traditional water bag is inconvenient for people to use. Since the hot water is gradually cooling down in a timely manner, the water bag cannot provide the warming ability after a short period of time. Then, the user must pour out the water inside the sealing bag and refill the hot water. In other words, the user must repeatedly refill the hot water frequently, which is very inefficient and inconvenient.
  In the other hand, it is convenient for the user to heat up the water inside the sealing bag by microwave oven. However, it is relatively dangerous for the user when the water inside the sealing bag is overheated. Accordingly, few seconds of contacting with the hot water will cause a serious burn. The overheated water inside the sealing bag will also cause a serious explosion.
  Likewise, by electrically connecting the heating element with the external power source, the water inside the sealing bag can be gently heated up by the heating element. However, when the water is heated, the volume of the water is expanded. When the water expands at a predetermined volume larger than the capacity of the sealing bag, the sealing bag will be forced to be popped and the hot water will be leaked from the sealing bag. Since the heating element is electrically connected to the power source, the hot water leaking from the sealing bag may cause an electrical short circuit or even a serious electric shock to the user. In other words, the user needs to find more secure and safe way to keep warm by using the water bag.