Heat dissipating device

The present invention relates to a heat dissipating device. More particularly, the present invention relates to a heat dissipating device in which an air flow is directed to a heat dissipating member by flapping a blade for making a driving unit and a device therefor small, improving heat dissipating efficiency and reducing noise therefrom.

CROSS-REFERENCE TO RELATED APPLICATION(S)

Pursuant to 35 U.S.C. §119(a), this application claims the benefit of earlier filing date and right of priority to Korean Patent Application No. 10-2009-0086593, filed on Sep. 14, 2009, the contents of which are hereby incorporated by reference herein in their entirety.

BACKGROUND

1. Field of the Disclosure

The present invention relates to a heat dissipating device. More particularly, the present invention relates to a heat dissipating device in which an air flow is directed to a heat dissipating member by flapping a blade for making thus permitting the size of a driving unit and a device therefor to be reduced, improving heat dissipating efficiency and reducing noise therefrom.

2. Discussion of the Related Art

Recently, electronic devices, such as lighting apparatus, display devices, handheld terminals, and so on, operate at increasingly faster speeds to increase performance and are quickly becoming lighter, thinner, shorter and smaller than before.

Users of these electronic device demand high performance as well as smaller sizes of the device, and technologies for integrating devices and increasing performance are also applied to these electronic devices.

As these electronic devices increase their performance and speed, the electronic devices generate more heat, increasing the failure rate of the electronic device, and require a heat dissipation design of the electronic device.

Particularly, in a case of an LED, since an environmental temperature change affects a performance and a lifetime of the LED heavily, it is essential that the lighting apparatus of LED has effective heat dissipation.

Along with this, a heat dissipating device is required, which is to be attached to a heat generation region of the electronic device for easy dissipation of the heat from the heat generation region.

In the related art, fans have been used as the heat dissipating device, in general. However, the fans have problems since they have high power consumption and the fan blades generate noise as the fans are made smaller.

SUMMARY OF THE DISCLOSURE

Accordingly, the present invention is directed to a heat dissipating device that substantially obviates one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a heat dissipating device which can improve heat dissipating efficiency.

Another object of the present invention is to provide a heat dissipating device which can make a size of a driving unit thereof smaller.

Furthermore, another object of the present invention is to provide a heat dissipating device which can reduce noise generated when the heat dissipating device is in operation.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a heat dissipating device includes a heat dissipating member or heat dissipater thermally coupled to a heat generating unit or generator and configured to transmit heat from the heat generating unit to the air, at least one blade for forming an air flow to at least a portion of the heat dissipating member by flapping, and a blade driving unit or drive for driving the blade to flap when operating.

The blade driving unit may drive the blade to flap in up/down directions within a predetermined range of angles during operation.

In this case, the blade driving unit may include at least one shaft, at least one magnet having an upper side and a lower side with polarities different from each other, at least one bobbin connected to the blade and configured to rotate up and down alternately within the predetermined range of angles on an axis of the shaft, and a coil wound on the bobbin spaced from the magnet for enabling to pass a current, wherein the bobbin may drive the blade as the bobbin is rotated by a force generated by the magnet and the coil when the current flows to the coil.

Preferably, the bobbin includes a guide portion having the coil wound thereon, wherein, when the bobbin is at a neutral position, a portion of the coil wound on the guide portion is positioned at a height corresponding to the upper side of the magnet and the other portion of the coil wound on the guide portion is positioned at a height corresponding to the lower side of the magnet.

In this instance, the current flowing to the coil may be an alternating current when the blade driving unit is in operation.

Moreover, preferably, intensity and a cycle of the current flowing to the coil are controllable.

And, the blade may include a first blade connected to one end of the bobbin and a second blade connected to the other end of the bobbin, the magnet may be arranged to pass through a receiving portion in the bobbin, and the shaft may pass through a hole formed to pass through the magnet.

In this case, the magnet may include a first magnet and a second magnet arranged parallel to the first magnet, the coil may include a first coil arranged opposite to the first magnet, and a second coil arranged opposite to the second magnet, and the first blade may be arranged opposite to the first coil and the second blade is arranged opposite to the second coil.

Moreover, a polarity of an upper side of the first magnet may be different from a polarity of an upper side of the second magnet

And, the blade may include a first blade and a second blade, the bobbin may include a first bobbin connected to the first blade and a second bobbin connected to the second blade, the magnet may include a first magnet arranged opposite to the first bobbin and a second magnet arranged opposite to the second bobbin, and the shaft may include a first shaft connected to the first bobbin and passing through a first hole formed to pass through the first magnet and a second shaft connected to the second bobbin and passing through a second hole formed to pass through the second magnet.

And, preferably, the blade driving unit further includes a magnetic spring member provided to the bobbin spaced from the magnet, the magnetic spring member being configured such that a restoration force is applied to the magnetic spring in a direction in which magnetic flux from the magnet is the smallest.

In this instance, the magnetic spring may include an iron piece having a center line positioned at a height corresponding to a boundary surface between the upper side and the lower side of the magnet which have polarities different from each other when the bobbin is at the neutral position.

And, the heat dissipating device may further include a housing for rotatably mounting opposite ends of the shaft thereon and fixedly securing the magnet thereto.

And, preferably, the heat dissipating member has one surface in contact with the heat generating unit and the other surface having a plurality of heat dissipating fins provided to an edge thereof spaced from one another.

In this instance, preferably, the blade and the blade driving unit are positioned in a space formed between the other surface of the heat dissipating member and the heat dissipating fins.

In another aspect of the present invention, a heat dissipating device includes a shaft, a bobbin connected to the shaft such that the bobbin rotates in up/down directions alternately on an axis of the shaft within a predetermined range of angle, and a blade connected to the bobbin for forming an air flow to a heat dissipating object by the rotation of the bobbin.

In another aspect of the present invention, a heat dissipating device includes a heat sink having a surface in contact with a heat generating unit and the other surface having heat dissipating fins arranged at an edge thereof to form a space on an inner side of the heat dissipating fins, a blade provided to the space for cooling down the heat dissipating fins as the blade produces an air flow by flapping, and a blade driving unit for driving the blade to flap.

In this instance, the heat generating unit may be an electronic device which generates heat as the electronic device is driven.

And, preferably, the heat generating unit may be one selected from an LED (Light Emitting Diode) lighting apparatus, a CPU (Central Processing Unit), a backlight unit, a display device, a hard disk drive, a portable terminal, a notebook computer, a computer module, and a projector.

And, the heat dissipating fins have bent regions, respectively.

DETAILED DESCRIPTION

FIG. 1illustrates a section of a heat dissipating device in accordance with a preferred embodiment of the present invention, schematically.

Referring toFIG. 1, the heat dissipating device10can include a heat dissipating member or heat dissipater100thermally coupled to a heat generating unit or heat generator150configured to transmit heat from the heat generating unit150to the air, at least one blade200to be flapped for causing an air flow to at least a portion of the heat dissipating member100, and a blade driving unit or blade drive300for driving the blade200to flap in operation.

The heat dissipating member100has one surface101in contact with the heat generating unit150, and the other surface102is provided with a plurality of heat dissipating fins110arranged at an edge thereof spaced from one another.

The heat from the heat generating unit150is transmitted to the heat dissipating fins110at the other surface102of the heat dissipating member100through the one surface101of the heat dissipating member100. Thus, the heat dissipating member100can be provided with the heat dissipating fins110to have an increased contact surface with air for making effective transmission of the heat from the heat generating unit150to external air. The heat dissipating member100can be called as a heat sink100in a view that the heat dissipating member100transmits the heat from the heat generating unit150to an outside of the device.

The heat generating unit150can be an electronic device which generates the heat as it is operated. The heat generating unit150will be described in detail, below.

There is a space120formed on an inner side of the heat dissipating fins110. That is, the space120is between the heat dissipating fins110and the other surface102of the heat dissipating member100, and the blade200and the blade driving unit300can be positioned in the space120.

The blade200can be defined as a wing for producing an air flow.

Therefore, the heat dissipating device10of the embodiment is advantageous in that the blade driving unit300, on the inner side of the heat dissipating fins110, flaps the blade200to cause the air flow forcibly for dissipating the heat transmitted to the heat dissipating fins110.

FIG. 2illustrates a section of a heat dissipating device in accordance with a preferred embodiment of the present invention schematically for describing operation thereof.

Since the heat dissipating fins110are arranged at the edges of the other surface102of the heat dissipating member100, the blade200and the blade driving unit300are mounted on the inner side of the heat dissipating fins110.

At an initial stage, the blade200is positioned at ‘A’ position. When the blade200is at a horizontal position thus, the horizontal position of the blade200will be called as a neutral position, hereafter. Upon putting the driving unit300into operation, the blade200moves between an upper position ‘B’ and a lower position ‘C’, flapping like a bird.

That is, the blade driving unit300is a driving unit for flapping the blade200up/down, for causing the air flow in up/down directions of the heat dissipating fins110.

Thus, the blade driving unit300can drive the blade200to flap in up/down directions within a predetermined range of angles during operation.

And, referring toFIG. 2, when two blades200are provided, the blades200can be driven independently, or dependent on movement of the other blade200, depending on a structure of the blade driving unit300.

The blade200can be formed to have a variety of shapes by adding curves and pass through holes thereto.

Thus, the flapping of the blade200causes the air flow on the inner side of the heat dissipating fins110, and the air flow is brought into contact with the heat dissipating fins110forcibly, thereby enabling to cool down the heat transmitted to the heat dissipating fins110.

Moreover, since the air flow caused by the flapping of the blade200has a great flowing pressure toward the heat dissipating fins110, the air flow can improve efficiency of dissipation of the heat remained in the vicinity of, or in spaces between, the heat dissipating fins110.

FIG. 3illustrates an exploded perspective view of a heat dissipating device in accordance with a preferred embodiment of the present invention schematically for describing a mounted state thereof, andFIG. 4illustrates a perspective view showing an assembled state of the heat dissipating device inFIG. 3.

Referring toFIGS. 3 and 4, the blade200and the blade driving unit300can be mounted to the inner side of the heat dissipating fins110of the heat dissipating member100.

The blade driving unit300can include at least one magnet380, a bobbin330having one end connected to the blade200, and a housing310for supporting the magnet380and the bobbin330. In this instance, by mounting the housing to the space120, the blade driving unit300and the blade200can be mounted to the heat dissipating member100.

In order to make the heat dissipating device10compact and small, it is preferable that the housing310has a height lower than the heat dissipating fins110.

It is preferable that the blade driving unit300flaps the blade200by an electromagnetic force, more specifically, a Lorentz force. For this, the blade driving unit300can be fabricated to include a structure in which a coil to which a current flow and a magnet which generates a magnetic field arranged opposite to, and spaced from, each other spaced.

A detailed structure of the blade driving unit300will be described with reference toFIGS. 5 and 6.

FIG. 5illustrates a perspective view of a blade driving unit in accordance with a preferred embodiment of the present invention schematically, andFIG. 6illustrates a perspective view of the blade driving unit inFIG. 5, partially.

Referring toFIGS. 5 and 6, the blade driving unit300can include at least one shaft320, at least one magnet380having an upper side and a lower side configured to have polarities different from each other, at least one bobbin330connected to the blade200configured to rotate in up/down directions alternately within a predetermined range of angle centered on an axis of the shaft320, and at least one coil370wound on the bobbin330spaced from the magnet380for allowing a current to flow therethrough.

The bobbin330rotates by a force generated by the magnet380and the coil370when the current flow to the coil370to drive the blade220. Such an action of the force and movement of the bobbin330and the blade220will be described in detail, later.

The bobbin330can be provided with a guide portion360for winding the coil370thereon. The coil370can be wound on the guide portion360more than once. And, there can be at least one recess361in one side of the guide portion360for mounting a magnetic spring362thereto. The magnetic spring362will be described later, in detail.

Moreover, the blade driving unit300can include a housing310for rotatably mounting opposite ends of the shaft320thereon and fixedly securing the magnet380thereto, additionally.

The housing310can be provided with one pair of bearings (not shown) for receiving the opposite ends of the shaft320.

The shaft320can be rotated smoothly by an external force as the shaft320is passed through a hole385(SeeFIG. 15) in the magnet and a hole (not shown) in the bobbin and placed in the bearings of the housing310.

Though the shaft320moves in the hole of the magnet380freely, the shaft320is fixed to the hole in the bobbin330to rotate the bobbin330together with the shaft320.

Therefore, at the time the bobbin330is moved by a force generated by the magnet380and the coil370, the magnet380does not move, and the blade200and the shaft320move following movement of the bobbin330, making the blade200flap.

Thus, the shaft320is mounted to pass both through the magnet380and the bobbin330, and the magnet380is arranged to pass through a receiving portion331in the bobbin330for enabling the bobbin330to move while the magnet380is stationary. It is preferable that the receiving portion331has a size which does not cause interference with the magnet380when the bobbin330rotates in the up/down directions.

The housing310has a seating portion (not shown) having a height enough to seat the magnet380thereon and allow the blade200to overhang over a lower side.

In order to facilitate assembly alignment and to provide excellent stability at the time of positioning of the housing310in the space120on the inner side of the heat dissipating fins110of the heat dissipating member100, the housing310can be provided with a flat plate having a shape which resembles the space120, and the seating portion of the housing310can be formed at the flat plate.

The blade200includes a first blade200aconnected to one end of the bobbin330and a second blade200bconnected to the other end of the bobbin330. And, the magnet380includes a first magnet380aand a second magnet380barranged parallel to the first magnet380a, and the coil370includes a first coil370aarranged opposite to the first magnet380aand a second coil370barranged opposite to the second magnet380b. In this instance, the first blade200ais arranged opposite to the first coil370aand the second blade200bis arranged opposite to the second coil370b.

By providing two blades200aand200b, cooling efficiency of the heat dissipating fins can be improved as the air flow becomes smoother.

Moreover, by making currents flow to the first coil370aand the second coil370bseparately, the blade200can be driven by a force generated between the first coil370aand the first magnet380aand a force generated between the second coil370band the second magnet380b.

In the embodiment, an upper side polarity of the first magnet380acan be made different from an upper side polarity of the second magnet380b.

A principle of the blade200driven by the blade driving unit300will be described with reference toFIG. 7.

FIG. 7illustrates a conceptual view for describing a force generated by a magnet and a coil in accordance with a preferred embodiment of the present invention, schematically. In more detail,FIG. 7illustrates the blade driving unit300seen from the first blade200a, while omitting elements thereof except the first magnet380aand the first coil370afor convenience's sake.

The first coil370ais arranged opposite to, and spaced therefrom, the first magnet380a(SeeFIGS. 5 and 6), and the first magnet380ahas upper side polarity and lower side polarity different from each other. It is assumed that the first magnet380ahas an S pole at the upper side381aand an N pole at the lower side382a.

Referring toFIG. 7, it is preferable that, at the time the bobbin330(SeeFIGS. 5 and 6) is at the neutral position, a portion of the first coil370awound on the guide portion360is positioned at a height corresponding to the upper side381aof the first magnet380a, and the other portion of the first coil370awound on the guide portion360is positioned at a height corresponding to the lower side381aof the first magnet380a.

That is, in a wound state, the upper side of the first coil370ais positioned at the height corresponding to the upper side381aof the first magnet380aand the lower side of the first coil370ais positioned at the height corresponding to the lower side382aof the second magnet380a.

In this instance, since the lower side382aof the first magnet is the N pole and the upper side381aof the first magnet is the S pole, the first coil370ais in a magnetic field formed in an upper side381adirection of the first magnet380a, wholly.

In this state, i.e., in the neutral position, if the current flows in the first coil370ain a direction of arrows shown inFIG. 7, a Lorentz force which is a force acting on a charged particle moving in a magnetic field acts on the first coil370a. A direction of the force acting on the first coil370ais according to the Fleming's left-hand rule.

In detail, the upper side of the first coil370aat the height of the upper side381aof the first magnet380ahas a force acting thereto upward in a vertical direction with reference to a surface of the drawing, and the lower side of the first coil370aat the height of the lower side382aof the first magnet380ahas a force acting thereto downward in a vertical direction with reference to a surface of the drawing.

At the end, as forces acting in directions different from each other act to the upper side and the lower side of the first coil370arespectively, the first coil370arotates.

In a case the current flows in a direction shown inFIG. 7, the coil370ashown inFIG. 6has a force which rotates in a clockwise direction acting thereto, to rotate the bobbin330in the clockwise direction on the shaft320, to drive the first blade200a. In this instance, since the second blade200bis also connected to the bobbin330, the second blade200balso rotates in the clockwise direction.

Opposite to this, since an electromagnetic force acts in a direction opposite to above if the current flows in a direction opposite to the arrows shown inFIG. 7, to rotate the bobbin330in an anti-clockwise direction on the shaft320.

That is, since the shaft320connected to the bobbin330is movable by an external force, the shaft320rotates in a regular or reverse direction following movement of the bobbin330.

At the end, as the blade200connected to the bobbin330moves up and down to flap, the blades200produces an air flow.

In this instance, the blade driving unit300does not apply a driving force to the shaft320directly, but moves the bobbin330by means of the electromagnetic force applied to the coil370to rotate the blade200. That is, the shaft320serves to provide a shaft for the bobbin330to rotate.

Since a force generated by the second magnet380band the second coil370bis similar to the force generated by the first magnet380aand the first coil370a, description of the force will be omitted.

Since the embodiment is configured such that the polarities of the upper side of the first magnet380aand the upper side of the second magnet380bare different from each other, it is preferable that directions of the currents to the first coil370aand the second coil370bare the same. If the directions of the currents to the first and second coils370aand370bare not same, since the direction of the rotating force acting to the first coil370aand the direction of the rotating force acting to the second coil370bare opposite to each other, a rotating force acting to an entire bobbin330can be reduced as the forces offset each other.

In the meantime, referring toFIGS. 5 and 6, the blade driving unit300of the embodiment can include a magnetic spring member362provided to the bobbin330spaced from the magnet380. The magnetic spring member is configured such that a restoration force is applied to the restoration force in a direction in which magnetic flux from the magnet300is the smallest, additionally. This will be described with reference toFIGS. 8 to 10.

FIG. 8illustrates a partial section showing a magnetic spring member placed in/fastened to a blade driving unit of the present invention schematically, andFIGS. 9A and 9Billustrate conceptual views for showing a relation between a magnet and a magnetic spring in accordance with a preferred embodiment of the present invention.FIG. 10illustrates a front view showing a state in which a blade is placed at a neutral position by a magnetic spring, schematically.

Referring toFIG. 8, the magnetic spring member362can be mounted to at least one recess361in the bobbin330, more specifically, in the guide portion360of the bobbin.

The recess361can be formed in a region of the guide portion360opposite to a region on which the coil370is wound. That is, the recess361is formed on a side opposite to a side on which the coil370is provided with reference to the guide portion360, for placing the magnetic spring member362therein.

It is preferable that the magnetic spring member362is an iron piece extended in a transverse direction.

Referring toFIG. 9A, an upper side381of the magnet380is an S pole and a lower side of the magnet380is an N pole.

And, referring toFIG. 9B, it is preferable that, at the time the bobbin330is at the neutral position, a center line of the magnetic spring member362is positioned at a height corresponding to a boundary surface of the upper side381and the lower side382of the magnet, which have opposite polarities. InFIG. 9B, the center line of the magnetic spring member362is marked with a dashed line.

That is, the center line of the magnetic spring member362falls on a line which separates the upper side381and the lower side382of the magnet380, which have opposite polarities.

In this instance, between the magnetic spring member362and the magnet380, there is a tendency of moving the magnetic spring member362to a point at which density of magnetic flux from the magnet380is minimized (a stable point at which force is the lowest).

In more detail, at the magnet380of the embodiment, while lines of magnetic forces start from a bottom of the lower side382which is the N pole and enter to a top of the upper side381which is the S pole, density of lines of the magnetic forces is the greatest at the bottom of the lower side382of the magnet and the top of the upper side381of the magnet, and the smallest in the vicinity of a line at which the lower side382and the upper side381of the magnet are separated. Therefore, when the magnetic spring member362oscillates in up/down directions, a restoration force is applied to the restoration force in a direction of the line of separation of the upper/lower sides of the magnet380.

The tendency of moving the magnetic spring member362to the point where the density of the magnetic flux is the smallest can be defined as a magnetic spring principle.

Therefore, even if no power is applied to the blade driving unit300, the center line of the magnetic spring member362is positioned at the boundary surface of the upper side381and the lower side382of the magnet380, enabling the magnetic spring member362to maintain the neutral position as shown inFIG. 10.

And, when the coil370and the magnetic spring member362rotate, a restoration force acts to the blade200in a direction opposite to the rotating direction.

Movement of the blade200will be described in detail, with reference toFIGS. 11 to 13.

FIGS. 11A to 11Cillustrate perspective views for describing a detailed operation of flapping of a blade in accordance with a preferred embodiment of the present invention,FIG. 12illustrates a waveform of a current applied to a coil in accordance with a preferred embodiment of the present invention, andFIG. 13illustrates a perspective view for describing a method for controlling a rotation angle and speed of a blade with a current applied to the coil, schematically.

As described before, a direction of a force which rotates the coil370by means of the magnet380and the coil370varies with a direction of a current to the coil370and a direction of a magnetic field from the magnet380. Since the magnet380is stationary, the magnetic field is fixed. Therefore, in order to make the blade200to flap as shown inFIGS. 11A˜11C, it is required to change the direction of the current to the coil370with time.

Therefore, it is preferable that the current to the coil370is an alternating current when the blade driving unit is in operation. In more detail, as shown inFIG. 12, it is preferable that the current has a sinusoidal wave form.

In the sinusoidal current wave form inFIG. 12, a direction of a force acting on the coil370when the current is a positive + direction wave is different from a direction of a force acting on the coil370when the current is a negative − direction wave.

When the current is the positive + direction wave, the force acts on the coil370such that the blade200has a position shown inFIG. 11A, and when the current is the negative − direction wave, the force acts on the coil370such that the blade200has a position shown inFIG. 11C.

And, when the current is at a crossing point of the positive + direction wave and the negative − direction wave, since no force acts on the coil370, the blade200tends to move to a position shown inFIG. 11B.

Referring toFIG. 12, if the current has the sinusoidal wave form, oscillating between a maximum value and a minimum value of a predetermined range, the bobbin330rotates up/down on the shaft within a predetermined range of angle, alternately. Thus, as the blade200flaps up and down repeatedly by the sinusoidal wave form current, the blade200produces forced convection.

Referring toFIG. 13, a rotating angle θ of the bobbin200is defined as an angle from the neutral position of the bobbin330(a position line marked with ‘P’) to a maximum rotated state (a position line marked with ‘K’) of the bobbin330.

Magnitude of the force acting on the coil370owing to the magnet380and the coil370having the current flowing thereto is proportional to intensity of the current to the coil370. That is, since the stronger the intensity of the current to the coil370, as the force tending to rotate the coil370becomes the stronger, the rotating angle θ of the blade200can also become the greater.

And, since the shorter a cycle of the sinusoidal wave form current to the coil370, the sharper a direction change of the force acting on the coil370, a rotating speed of the blade200becomes the faster.

Therefore, it is preferable that the intensity and cycle of the current to the coil370are controllable.

That is, referring toFIG. 12, by controlling the intensity C of the sinusoidal wave form current, the angle θ of the blade200can be controlled, and by controlling the cycle T of the sinusoidal wave form current, the rotating speed of the blade200can be controlled.

In this instance, it is preferable that the angle θ of the blade200meets a condition of 0°≦θ<90°.

Though a blade driving unit has been described, which has single bobbin200to move two blades200aand200bdependant on each other, a configuration of the blade driving unit is not limited to above.

FIG. 14illustrates a conceptual view of a blade driving unit in accordance with another preferred embodiment of the present invention, schematically.

Referring toFIG. 14, the blade can include first and second blades200aand200b, the bobbin can include a first bobbin330aconnected to the first blade200aand a second bobbin330bconnected to the second blade200b, and the magnet can include a first magnet380aarranged opposite to the first bobbin330aand a second magnet380barranged opposite to the second bobbin330b.

The shaft can include a first shaft320aconnected to the first bobbin330aand passes through a first hole formed to pass through the first magnet380a, and a second shaft320bconnected to the second bobbin330band passes through a second hole formed to pass through the second magnet380b.

Such a configuration of the blade driving unit enables independent control of the currents to the first coil370aand the second coil370b, enabling to drive the first blade200aand the second blade200b, independently.

FIGS. 15A to 15Dillustrate conceptual views of variations of magnet(s) and hole(s) in the magnet(s) in accordance with a preferred embodiment of the present invention, schematically.

As described before, the magnet has the upper side and the lower side having polarities different from each other, and is required to have the hole(s) formed therein.

In this instance, it is preferable that the pass through hole passes through a boundary surface at which the regions of the magnet having different polarities are in contact.

For an example, the hole is formed at the boundary surface of the upper side which is the S pole and the lower side which is the N pole.

FIGS. 15A and 15Billustrate single structured magnets380having polarities of the upper side381and the lower side382different from each other respectively, andFIGS. 15C and 15Dillustrate double structured magnet in which an upper side381apolarity of the first magnet380ais different from an upper side381bpolarity of the second magnet380b, and a lower side382apolarity of the first magnet380ais different from a lower side382bpolarity of the second magnet380b, respectively.

In this instance, each of the magnets inFIGS. 15A and 15Bhas one hole with a reference symbol ‘385a’ for placing the shaft therein, and each of the magnets inFIGS. 15C and 15Dhas two holes with reference symbols ‘385a’ and ‘385b’. Thus, the present invention can provide at least one hole which passes through the magnet.

Though the blade driving unit has been described, which has a structure in which the magnet is fixedly secured to the housing and the coil is connected to the blade, the present invention is not limited to this. For an example, a structure can be applied, in which the coil is fixedly secured to the housing and the magnet is connected to the blade, which will be described with reference toFIGS. 16A,16B and17.

FIGS. 16A and 16Billustrate conceptual views of a blade driving unit in accordance with another preferred embodiment of the present invention, schematically.

A heat dissipating device of the embodiment has a structure in which a coil is fixedly secured and a blade moves to cause flapping of the blade for dissipating heat.

That is, the blade flaps as the magnet is mounted to a bobbin connected to the blade, and movement takes place by an electromagnetic force from a coil wound on a guide portion fixed to the housing.

FIG. 16Aillustrates a heat dissipating device having one blade and single coil and single magnet arranged opposite to each other, wherein the guide portion360is formed at the housing310and the coil370is wound on the guide portion360.

The magnet is positioned opposite to, and spaced from, the coil370, the magnet380has a hole385for passing through of the shaft, the magnet380is mounted to the bobbin330, and the bobbin330is connected to single blade300.

And,FIG. 16Billustrates a heat dissipating device having two blades and single coil and single magnet arranged opposite to each other, wherein the two blades200aand200bare connected to the bobbin330inFIG. 16A.

FIG. 17illustrates a conceptual view of a blade driving unit in accordance with another preferred embodiment of the present invention, schematically.

A heat dissipating device of the embodiment has two blades and one pair of coils and magnets arranged opposite to each other, wherein first and second guide portions360aand360bare formed at a housing310, and the coils370aand370bare wound on the first and second guide portions360aand360b, respectively.

And, the first magnet383aand the second magnet383bare positioned at regions opposite to, and spaced from, the coils370aand370bwound on the first and second guide portions360aand360brespectively, the first and second magnets383aand383bhave holes385for passing through the shafts respectively, the first magnet383ais mounted to the first bobbin330aand the second magnet383bis mounted to the second bobbin330b.

The first bobbin330aand the second bobbin330bmay or may not be connected to each other.

The first bobbin330ahas the first blade200aconnected thereto, and the second bobbin330bhas the second blade200bconnected thereto.

Since the first and second magnets383aand383bhave the holes385formed therein respectively, the holes385have the first and second shafts placed therein respectively, the first bobbin330aconnects the first shaft to the first blade200aand the second bobbin330bconnects the second shaft to the second blade200b.

Since operation of the heat dissipating device shown inFIGS. 16A,16B and17are similar to the foregoing embodiment, description of the operation will be omitted.

FIG. 18illustrates a section of heat dissipating fins in accordance with another preferred embodiment of the present invention, schematically.

Referring toFIG. 18, the each of the heat dissipating fins110can have a bent region.

That is, it is preferable that each of the heat dissipating fins110, arranged at the edge of the other surface of the heat dissipating member at fixed intervals, has the bent region for effective reception of an air flow formed by the flapping of the blade positioned on the inner side of the heat dissipating fins110, thereby increasing heat dissipating efficiency.

This configuration enables improvement of the heat dissipating efficiency of the heat dissipating fins110as the air flow is brought into contact to the bent region.

The bent regions of the heat dissipating fins110can make a sectional form of the heat dissipating fins110to be a whirling pattern.

At the end, the bent regions at the heat dissipating fins110increase contact areas with the air flow, enabling smooth cooling of the heat dissipating fins110.

FIG. 19illustrates a section of a heat generating unit provided to a heat dissipating device in accordance with a preferred embodiment of the present invention.

As described before, the heat generating unit, which is defined as an electronic device which generates heat as it is driven, is in contact with one side of the heat dissipating member100of the heat dissipating device such that the air flow caused by the flapping of the blade200dissipates the heat transmitted to the heat dissipating fins110from the heat generating unit via the one side of the heat dissipating member100, effectively.

The heat generating unit can be any one selected from an LED (Light Emitting Diode) lighting apparatus, a CPU (Central Processing Unit), a backlight unit, a display device, a hard disk drive, a portable terminal, a notebook computer, a computer module, and a projector. That is, the heat dissipating device of the present invention has wide applications.

FIG. 19illustrates an example in which an LED lighting apparatus500is applied as the heat generating unit.

As has been described, the heat dissipating device of the present invention has the following advantages.

The forced air flow from an inner side of the heat dissipating fins permits effective dissipation of heat transmitted to the heat dissipating fins. And, the bringing of the air flow with a high flow pressure caused by flapping of the blade into contact with the heat dissipating fins enhances heat dissipating efficiency of the heat at the heat dissipating fins and in the vicinity thereof.

And, the flapping of the blade within a fixed range of angle permits to make the heat dissipating device and the driving unit small.

Moreover, the heat dissipating device can cool down the heat dissipating member in a low noise state since the heat dissipating device produces no noise caused by continuous fan rotation.

Along with this, the bent regions of the heat dissipating fins, increasing contact areas to the air flow, permits smooth cooling down of the heat dissipating fins.