1. Field of the Invention
The invention relates to a transformer and a backlight apparatus. More particularly, the invention relates to a transformer with a built-in protective capacitor and a backlight apparatus with this transformer structure.
2. Description of the Prior Art
In recent years, along with the gradually enlarged size of the liquid crystal display panel, the backlight apparatus comprising a plurality of Cold Cathode Fluorescent Lamps (CCFL) is widely utilized to provide the high quality light source needed in the liquid crystal display panel. Each lamp's brightness of the multi-lamp backlight apparatus is related to the current flow through said lamp. Therefore, the design issues of the multi-lamp backlight apparatus include how to maintain the currents through all lamps equally, and how to prevent unbalanced occurrences among the lamps. Additionally, the protective function for the circuit of the multi-lamp backlight apparatus under some faulty conditions (e.g. short circuit, open circuit) becomes a critical issue in the multi-lamp backlight system as well.
In the traditional backlight system, the high-voltage output of the transformer is usually coupled to a high-voltage capacitor on the circuit board. The high-voltage capacitor is used to adjust the output signal of the transformer. Furthermore, the high-voltage capacitor can be connected in series with another capacitor or a resistor to form a voltage-dividing circuit, which is one part of the protective circuit.
Please refer to
The transformer 14, driven by the power module 10, is used to push the load (lamp 12). The high-voltage side of the transformer 14 is coupled to the lamp 12 and a capacitor 16. The capacitor 16 is further connected in series with another passive component 18 (which can be a resistor or a capacitor). The capacitor 16 and the passive component 18 form a voltage-dividing circuit. The voltage-dividing circuit can generate the feedback input for the protective feedback circuit 20.
Please refer to
As shown in
Therefore, the invention discloses a transformer and a backlight apparatus utilizing the transformer, to solve the said problems.
A scope of the invention is to provide a transformer. The transformer is suitable for a backlight module with a first lamp. The transformer includes a bobbin, a secondary winding, a first conductive plate and a second conductive plate.
According to an embodiment of the invention, the bobbin has a high-voltage winding region and a first pin thereon. The secondary winding is wound on the high-voltage winding region. One end of the secondary winding is electrically connected to the first pin. The first pin is coupled to the first lamp of the backlight module. The high-voltage winding region has a first separation plate. The first conductive plate is disposed within the first separation plate. The first conductive plate is electrically connected to the first pin. The second conductive plate is disposed within the first separation plate. The second conductive plate is located corresponding to the first conductive plate, such that the first conductive plate and the second conductive plate form a first capacitor.
Another scope of the invention is to provide a transformer. The transformer is suitable for a backlight module with a first lamp and a second lamp. The transformer includes a bobbin, a first secondary winding, a second secondary winding, a first conductive plate, a second conductive plate, a third conductive plate and a fourth conductive plate.
According to another embodiment of the invention, the bobbin has a first high-voltage winding region, a second high-voltage winding region, a first pin and a second pin thereon. The first secondary winding is wound on the first high-voltage winding region. One end of the first secondary winding is electrically connected to the first pin. The first pin is coupled to the first lamp of the backlight module. The second secondary winding is wound on the second high-voltage winding region. One end of the second secondary winding is electrically connected to the second pin. The second pin is coupled to the second lamp of the backlight module. The first high-voltage winding region has a first separation plate. The first conductive plate is disposed within the first separation plate. The first conductive plate is electrically connected to the first pin. The second conductive plate is disposed within the first separation plate. The second conductive plate is located corresponding to the first conductive plate, such that the first conductive plate and the second conductive plate form a first capacitor. The second high-voltage winding region has a second separation plate. The third conductive plate is disposed within the second separation plate. The third conductive plate is electrically connected to the second pin. The fourth conductive plate is disposed within the second separation plate. The fourth conductive plate is located corresponding to the third conductive plate, such that the third conductive plate and the fourth conductive plate form a second capacitor.
Another scope of the invention is to provide a backlight apparatus. The backlight apparatus includes a power module, a first lamp and a transformer. The transformer includes a bobbin, a primary winding, a secondary winding, a first conductive plate and a second conductive plate.
According to another embodiment of the invention, the bobbin has a low-voltage winding region, a high-voltage winding region and a first pin thereon. The primary winding is wound on the low-voltage winding region. The primary winding is coupled to the power module. The secondary winding is wound on the high-voltage winding region. One end of the secondary winding is electrically connected to the first pin. The first pin is coupled to the first lamp of the backlight apparatus. The high-voltage winding region has a first separation plate. The first conductive plate is disposed within the first separation plate. The first conductive plate is electrically connected to the first pin. The second conductive plate is disposed within the first separation plate. The second conductive plate is located corresponding to the first conductive plate, such that the first conductive plate and the second conductive plate form a first capacitor.
Another scope of the invention is to provide a backlight apparatus. The backlight apparatus includes a power module, a first lamp, a second lamp and a transformer. The transformer includes a bobbin, a primary winding, a first secondary winding, a second secondary winding, a first conductive plate, a second conductive plate, a third conductive plate and a fourth conductive plate.
According to another embodiment of the invention, the bobbin has a low-voltage winding region, a first high-voltage winding region, a second high-voltage winding region, a first pin and a second pin thereon. The primary winding is wound on the low-voltage winding region. The primary winding is coupled to the power module. The first secondary winding is wound on the first high-voltage winding region. One end of the first secondary winding is electrically connected to the first pin. The first pin is coupled to the first lamp of the backlight apparatus. The second secondary winding is wound on the second high-voltage winding region. One end of the second secondary winding is electrically connected to the second pin. The second pin is coupled to the second lamp of the backlight apparatus. The first high-voltage winding region has a first separation plate. The first conductive plate is disposed within the first separation plate. The first conductive plate is electrically connected to the first pin. The second conductive plate is disposed within the first separation plate. The second conductive plate is located corresponding to the first conductive plate, such that the first conductive plate and the second conductive plate form a first capacitor. The second high-voltage winding region has a second separation plate. The third conductive plate is disposed within the second separation plate. The third conductive plate is electrically connected to the second pin. The fourth conductive plate is disposed within the second separation plate. The fourth conductive plate is located corresponding to the third conductive plate, such that the third conductive plate and the fourth conductive plate form a second capacitor.
Compared with prior art, there are at least two conductive plates disposed within the bobbin of the transformer according to the embodiment of the backlight apparatus of the invention. The conductive plates are parallel-arranged and separated by a certain distance, such that a capacitance effect exists between the pair of conductive plates. The conductive plates can be coupled to the high-voltage side of the transformer and can serve as the protective capacitor of the circuit of the backlight apparatus. Accordingly, the transformer and the backlight apparatus of the invention can be implemented with this low-cost and compact-sized circuit structure.
The advantage and spirit of the invention may be understood by the following recitations together with the appended drawings.
Please refer to
In practical applications, the main body of the transformer 34 is the bobbin 340. The bobbin 340 is used to support the windings and accommodating the magnetic core. The bobbin can be made of an isolating material, e.g. Nylon, Polyethylene terephthalate (PET). Generally, there can be some separation plates disposed on the bobbin 340 for defining different winding regions.
In the embodiment, the bobbin 340 has a low-voltage winding region 3400, a high-voltage winding region 3402, a pin PIN1 and another pin PIN2. The primary winding 342 is wound on the low-voltage winding region 3400 and coupled to the power module 30. The secondary winding 344 is wound on the high-voltage winding region 3402. One end of the secondary winding 344 is electrically connected to the pin PIN1. The pin PIN1 is further coupled to the lamp 32 of the backlight apparatus 3.
There is a specific ratio between the turn numbers of the primary winding 342 and the secondary winding 344. Based on the electromagnetic induction, the primary winding 342 driven by the power module 30 induces the secondary winding 344 on the same magnetic loop, therefore, the induced secondary winding 344 generates an induced output for driving the lamp 32. In other words, the transformer 34 in the embodiment can be the one-to-one transformer for driving one singular load. Besides, the backlight apparatus 3 in the embodiment includes singular one-to-one transformer 34, which can correspond to singular lamp 32. In practical applications, the backlight apparatus may include multiple transformers at the same time, for corresponding to more lamps at once. In other words, the amount of the transformers in the backlight apparatus is not limited to one. The structure with multiple transformers is known by the person skilled in the art.
As shown in
The conductive plate C2 is disposed at the location corresponding to the conductive plate C1. The conductive plate C1 and the conductive plate C2 are made of conductive material, which can be metal material. According to the theory of plate capacitor, an equivalent capacitor can be formed between these two metal plates (the conductive plates C1, C2), which are separated by a certain distance and opposite disposed within the dielectric body (the separation body 34021).
The capacitance of the capacitor can be designed by adjusting the specification of the conductive plates C1, C2. For example, the capacitance of a plate capacitor, which is formed by two parallel conductive plates in identical size, is about εA/d (when A>>d2), wherein “ε” represents the dielectric index of the dielectric material (separation plate 34021); “A” represents the area of the conductive plate; “d” represents the distance between two conductive plates (conductive plate C1 and conductive plate C2). Accordingly, the two conductive plates disposed within the separation plate on the high-voltage side of the transformer can serve as a built-in capacitor, to save the extra costs and space of implementing the additional high-voltage capacitor on the circuit board.
It should be noticed that, in the first embodiment, when the built-in capacitor are equivalently formed by the conductive plate C1 and the conductive plate C2, the pin PIN2 electrically connected with the conductive plate C2 can be an open circuit (as shown in
Please refer to
The passive component 36′ can be a resistor, a capacitor or an inductor. The passive component 36′ is connected in series with the built-in capacitor formed by the conductive plates C1, C2 in the transformer 34′, to form a voltage-dividing circuit. The voltage-dividing output of the voltage-dividing circuit can be designed by adjusting the size of the conductive plates, the distance between the conductive plates or the index of the passive component 36′ on the circuit board. The voltage-dividing output of the voltage-dividing circuit is used for feed back to the input stage of the protective feedback circuit 38′, so as to achieve the protective function for the transformer circuit. The behavior of the voltage-dividing circuit and the protective feedback circuit 38′ is similar to one of the feedback structure with voltage-dividing circuit including the high-voltage capacitor in prior art. The theory of the feedback structure in prior art is well known by the person skilled in the art, and is not repeated here.
It is important to notice that the backlight apparatus 3′ does not need to implement the additional high-voltage capacitor on the circuit board. The transformer 34′ utilizes two conductive plates disposed within the separation plate on the high-voltage side, to serve as the built-in capacitor on the high-voltage side of the transformer 34′. Accordingly, it saves the extra space of implementing the additional high-voltage capacitor on the circuit board.
Please refer to
In this embodiment, the bobbin 540 further includes a pin PIN3 and a pin PIN4. The conductive plate C3 is electrically connected with the pin PIN3. The pin PIN3 is electrically connected to one end of the secondary winding 544 and coupled to the lamp 52b. The conductive plate C4 is electrically connected to the pin PIN4. The pin PIN4 can be an open circuit (as shown in
Based on the aforesaid structure, the conductive plate C3 and the conductive plate C4 are disposed in pair to form a capacitor. This means that on the high-voltage side of the transformer 54, there are two pairs of the conductive plates. One pair of the conductive plate C1 and the conductive plate C2 corresponds to the lamp 52a. Another pair of the conductive plate C3 and the conductive plate C4 corresponds to the lamp 52b. Accordingly, the one-to-two transformer 54 and backlight apparatus 5 with the built-in protective capacitors are formed.
Please refer to
The backlight apparatus 7 includes a power module 70, a lamp 72a, a lamp 72b and a transformer 74. The transformer 74 includes a bobbin 740, a primary winding 742, a first secondary winding 744, a second secondary winding 746, a conductive plate C1, a conductive plate C2, a conductive plate C3 and a conductive plate C4.
In the embodiment, the bobbin 740 has a low-voltage winding region 7400, a first high-voltage winding region 7402, a second high-voltage winding region 7404, a pin PIN1, a pin PIN2, a pin PIN3 and a pin PIN4. The primary winding 742 is wound on the low-voltage winding region 7400. The primary winding 742 is coupled to the power module 70.
The first secondary winding 744a is wound on the first high-voltage winding region 7402. One end of the first secondary winding 744 is electrically connected to the pin PIN1. The pin PIN1 is coupled to the lamp 72a of the backlight apparatus 7.
The first high-voltage winding region 7402 has a separation plate 74021. The conductive plate C1 and the conductive plate C2 are disposed within the separation plate 74021. The conductive plate C1 is electrically connected to the pin PIN1 and further coupled to the lamp 72a. The conductive plate C2 is electrically connected to the pin PIN2. The conductive plate C2 is disposed at the location corresponding to the conductive plate C1. The conductive plate C1 and the conductive plate C2 can be made of metal material. According to the theory of plate capacitor, an equivalent capacitor can be formed between the conductive plate C1 and the conductive plate C2.
The second secondary winding 746 is wound on the second high-voltage winding region 7404. One end of the second secondary winding 746 is electrically connected to the pin PIN3. The pin PIN3 is coupled to the lamp 72b of the backlight apparatus 7.
The second high-voltage winding region 7404 has a separation plate 74041. The conductive plate C3 and the conductive plate C4 are disposed within the separation plate 74041. The conductive plate C3 is electrically connected to the pin PIN3. The conductive plate C4 is disposed at the location corresponding to the conductive plate C3. The conductive plate C3 and the conductive plate C4 can be made of metal material. According to the theory of plate capacitor, an equivalent capacitor can be formed between the conductive plate C3 and the conductive plate C4.
Based on the aforesaid structure, on the high-voltage side of the transformer 74, there are two pairs of the conductive plates. One pair of the conductive plate C1 and the conductive plate C2 corresponds to the lamp 72a. Another pair of the conductive plate C3 and the conductive plate C4 corresponds to the lamp 72b. Accordingly, the one-to-two transformer 74 and backlight apparatus 7 with the built-in protective capacitors are formed.
Please refer to
Compared with the backlight apparatus 7 in the third embodiment, the transformer 94 of the backlight apparatus 9 further includes a conductive plate C5, a conductive plate C6, a conductive plate C7 and a conductive plate C8. In other words, the transformer 94 totally includes eight conductive plates. As shown in
In this embodiment, the conductive plate C5 and the conductive plate C6 are disposed in pair to form a capacitor corresponding to the lamp 92c, and the conductive plate C7 and the conductive plate C8 are disposed in pair to form a capacitor corresponding to the lamp 92d. That is to say, on the high-voltage side of the transformer 94, there are four pairs of the conductive plates (conductive plate C1 and conductive plate C2, conductive plate C3 and conductive plate C4, conductive plate C5 and conductive plate C6, conductive plate C7 and conductive plate C8), which can form four capacitors for corresponding to four load (lamp 92a, lamp 92b, lamp 92c, lamp 92d) respectively. Accordingly, the one-to-four transformer 94 and backlight apparatus 9 with the built-in protective capacitors are formed.
Compared with prior art, there are at least two conductive plates disposed within the bobbin of the transformer according to the embodiment of the backlight apparatus of the invention. The conductive plates are parallel-arranged and separated by a certain distance, such that a capacitance effect exists between the pair of conductive plates. The conductive plates can be coupled to the high-voltage side of the transformer and can serve as the protective capacitor of the circuit of the backlight apparatus. Accordingly, the transformer and the backlight apparatus of the invention can be implemented with this low-cost and compact-sized circuit structure.
With the example and explanations above, the features and spirits of the invention will be hopefully well described. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teaching of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Number | Date | Country | Kind |
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097221585 | Dec 2008 | TW | national |