BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a fan-shaped far- infrared heater, and more particularly to a fan-shaped far- infrared heater including a ceramic-coated quartz tube arranged around a coil-wound radiation member, thereby being capable of radiating an increased amount of heat and obtaining an enhancement in durability while preventing accidents caused by electric shock and fire accidents.

Description of the Related art As is well known, the heat transfer method, which has been used in traditional heaters, is a heat transfer method utilizing convection of air heated by heat generated when combustible products are burnt. However, such a heat transfer method utilizing convection of hot air involves a considerable loss of heat and a non-uniform temperature distribution in the interior of an associated heater, as compared to the methods utilizing radiation of heat. Since the heat transfer method utilizing convection of hot air is implemented using fuel such as coal or petroleum, it has many problems involved with the use of fuel, for example, a considerable expense and

generation of fumes. In order to solve these problems, a variety of electric heaters have been proposed which utilize electricity, that is, a pollution-free energy source not involving generation of odor and fumes. Recently, multi- functional far-infrared heaters which emit far-infrared rays having a considerable quantity of heat while exhibiting good effects on the user's health have also been highlighted.

Referring to Fig. 1, a conventional fan-shaped far- infrared heater is illustrated. As shown in Fig. 1, the heater includes a base 10 provided with power supply means and control knobs 11 for rotation and temperature adjusting functions, a stem 20 extending upwardly from the base 10, a rotating unit 30 rotatably mounted to the upper end of the stem 20, and a reflector 40 fixedly mounted to the rotating unit 30. A far-infrared heater unit 50 is mounted to the rotating unit 30 in such a fashion that it is arranged at the center of the reflector 40. The stem 20 supports the rotating unit 30 while providing a passage through which electrical leads extend to supply electric power from the power supply means to the far-infrared heater unit 50. The rotating unit 30 serves to rotate the far-infrared heater unit 50. The reflector 40 forwardly radiates heat emitted from the far- infrared heater unit 50. A protection grill 60 is detachably attached to a front end of the reflector 40.

Now, the essential configuration of the conventional

fan-shaped far-infrared heater, that is, the far-infrared heater unit 50, will be described with reference to Fig. 2.

As shown in Fig. 2, the far-infrared heater unit 50 includes a radiation member 51 made of ceramic, and a nichrome wire coil 52 wound around the radiation member 51. The far-infrared heater unit 50 is fixedly mounted to an iron support member 55 centrally mounted to the reflector 40. When electric power is applied to the coil 52, far-infrared rays are emitted from the radiation member 51.

Typically, far-infrared rays have a wavelength of 5.6 to 1,000 um, longer than that of the red component of visible light. When such far-infrared rays are used to provide concentrated heat based on radiation, it is possible to obtain efficient heat transfer effects because most objects irradiated by the far-infrared rays exhibit strong energy absorption characteristics.

Currently, fan-shaped far-infrared heaters having a heat transfer capacity rated for a floor space of 8 to 12 pyong (26.2 to 39.6 m2) are commercially available. In practical use, however, they cannot provide sufficient heating effects because of an insufficient quantity of heat generated therefrom and a short heat transfer extent thereof. In the above mentioned fan-shaped far-infrared heater in which the coil 52 is arranged around the radiation member 51 while being outwardly exposed, there is a possibility of fire accidents

where the coil is accidentally cut, and then comes into contact with the reflector 40 or protection grill 60.

Furthermore, there is a possibility of accidents caused by electric shock where a child carelessly touches the coil 40 using a metal object. In addition, there is a drawback in that the life of the heater is reduced due to an oxidation phenomenon occurring at the surface of the coil by dust covered over the exposed coil, and loss of elasticity occurring in the coil by virtue of repeated thermal expansion and contraction.

In order to solve the problems of the above mentioned fan-shaped far-infrared heater, several methods have been proposed. For example, Korean Utility Model Application No.

1999-14700 discloses a method in which as shown in Fig. 3, a metallic wire mesh 70 is fitted around the radiation member 51 serving as a heating element. Another method is disclosed in Korean Utility Model Application No. 2000-19762. In accordance with this method, as shown in Fig. 4, glass tubes 58 each enclosing a coil 20 are arranged around the radiation member 51 while being firmly held by upper and lower flanges 59.

Although these methods provide effects of protecting the heating element from external impact or preventing the coil from being oxidized, thereby increasing the life of the heater, they cannot solve the problems involved with the

heater itself, that is, generation of insufficient quantity of heat and a degradation in durability of the coil caused by repeated thermal expansion and contraction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above mentioned problems, and an object of the invention is to provide a fan-shaped far-infrared heater configured to convert visible rays, emitted from a heating element, into far- infrared rays, thereby achieving generation of increased quantity of heat, while preventing a nichrome coil included in the heating element from being damaged in spite of repeated thermal expansion and retraction, thereby increasing the durability of the nichrome coil.

In accordance with the present invention, this object is accomplished by providing a fan-shaped far-infrared heater comprising a base, a stem extending upwardly from the base, a rotating unit rotatably mounted to an upper end of the stem, and a reflector fixedly mounted to a front end of the rotating unit, an far-infrared heater unit centrally mounted to the reflector, the heater unit including a radiation member and a nichrome coil wound around the radiation member, and a protection grill detachably attached to a front end of the reflector, further comprising: a quartz tube fitted around the

far-infrared heater unit and coated with a ceramic layer adapted to emit far-infrared rays.

BRIEF DESCRIPTION OF THE DRAWINGS The above objects, and other features and advantages of the present invention will become more apparent after a reading of the following detailed description when taken in conjunction with the drawings, in which: Fig. 1 is a perspective view illustrating the outer construction of a conventional fan-shaped far-infrared heater; Fig. 2 is a sectional view illustrating a far-infrared heating unit shown in Fig. 1; Fig. 3 is an exploded perspective view illustrating a conventional metallic wire mesh to be fitted around the far- infrared heating unit; Fig. 4 is a perspective view illustrating another conventional far-infrared heating unit; Fig. 5 is an exploded perspective view illustrating an essential part of a fan-shaped far-infrared heater according to the present invention; and Fig. 6 is an assembled sectional view illustrating the essential part of the fan-shaped far-infrared heater according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, a preferred embodiment of the present invention will be described with reference to Figs. 5 and 6 illustrating only the essential part of a fan-shaped far-infrared heater, that is, a far-infrared heater unit according to the present invention, which is distinguishable from the conventional fan- shaped far-infrared heater shown in Figs. 1 to 4. Of course, the present invention is not limited to the illustrated embodiment. In Figs. 5 and 6, elements respectively corresponding to those in Figs. 1 to 4 are denoted by the same reference numerals.

The far-infrared heater unit 50, which is an essential part of the fan-shaped far-infrared heater according to the present invention, includes a cylindrical radiation member 51 made of ceramic, and a coil 52 wound around the radiation member 51. The radiation member 51 has a constant diameter at a portion thereof, on which the coil 52 is wound, while having a flared portion at a front end thereof. The far-infrared heater unit 50 also includes a ceramic-coated quartz tube 56 arranged around the radiation member 51 while being spaced apart from the radiation member 51 by a desired distance, a support member 57 made of ceramic and adapted to fix the radiation member 51 and quartz tube 56, and an iron bracket member 55 adapted to fixedly mount the far-infrared heater

unit 50 to a central portion of the reflector 40. The radiation member 51 is coupled to the ceramic support member 57 by means of a bolt 53 and a nut 54.

The structure of the ceramic support member 57 will now be described in detail. The ceramic support member 57 has a structure having two cylindrical portions of different diameters. A bolt insertion hole 571 is centrally formed at the ceramic support member 57 so as to couple the ceramic support member 57 to the radiation member 51 using the bolt 53 and nut 54. The ceramic support member 57 is also provided with three small holes 572 arranged around the bolt insertion hole 571 while being uniformly spaced apart from one another in a circumferential direction. The small holes 572 serve to allow nichrome coils to pass therethrough, respectively.

Grooves are also formed at a rear end of the ceramic support member 57 in order to couple the ceramic support member 57 to the iron bracket member 55.

The radiation member 51 is in contact with the ceramic support member 57 at its rear end in its coupled state. The radiation member 51 is provided at its rear portion with a central bolt insertion hole 571'and three small holes 572'to be aligned with the bolt insertion hole 571 and small holes 572 of the ceramic support member 57, respectively. As mentioned above, the radiation member 51 also has the flared portion at its front end. The flared portion provides an

enlarged exposure area so as to allow the reflector 40 to uniformly and widely radiate far-infrared rays in a forward direction.

Although not shown in Figs. 5 and 6, the fan-shaped far- infrared heater of the present invention also includes elements respectively corresponding to the base 10, stem 20, rotating unit 30, reflector 40, and front grill 60 of Fig. 1.

Since these elements are well known, no description of those elements will be provided.

Now, the procedure of assembling the elements of the heater according to the present invention will be described.

First, the ceramic-coated quartz tube 56 is fitted around the radiation member 51. Thereafter, three nichrome wires emerging from respective small holes 572'of the radiator member 51 are inserted into respective small holes 572 of the ceramic support member 57. In this state, the radiator member 51 and ceramic support member 57 are coupled together by inserting the bolt 53 into the central bolt holes 571 and 571', and threadedly coupling the bolt 53 with the nut 54.

Thus, the elements of the far-infrared heater unit 50 are completely assembled together. The far-infrared heater unit 50 is then engaged with the iron support member 55 fixedly mounted to the central portion of the reflector 40.

Accordingly, the assembling procedure for the heater is completed.

In the far-infrared heater having the above described configuration according to the present invention, electric power is supplied to the coil 52 in a power-on state of the heater. Heat is generated from the coil 52 by the supplied electric power, and transferred to the radiation member 51 while being transferred to the quartz tube 56 so that it is directly radiated by the quartz tube 56. Although the heat generated from the coil 52 is transferred along two paths, it finally passes through the quartz tube 56 which serves to convert visible rays into far-infrared rays. Accordingly, heat is irradiated along with a large amount of far-infrared rays.

Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

As apparent from the above description, in the fan- shaped far-infrared heater according to the present invention, the ceramic-coated quartz tube serving to convert visible rays into far-infrared rays is arranged around the heater unit.

Accordingly, it is possible to effectively reduce visible rays emitted from the ceramic material of the heater unit while increasing the amount of emitted far-infrared rays. As a

result, an increased amount of heat is radiated, and an enhanced heating effect is obtained. Since the coil is covered by the quartz tube impervious to heat, the coil is effectively prevented from being damaged in spite of repeated thermal expansion and retraction. Accordingly, the durability of the nichrome coil is increased. In addition, it is possible to prevent accidents caused by electric shock, fire accidents, and an oxidation phenomenon due to dust collecting on the surface of the coil because the coil is shielded by the quartz tube without being outwardly exposed.