JP5031781B2 - Inverter transformer - Google Patents

Description

  The present invention relates to an inverter transformer used in an inverter module used in a liquid crystal panel backlight unit, and more particularly to an inverter transformer suitable for a backlight unit of a large liquid crystal panel that requires multiple lighting.

  An inverter module for lighting a discharge tube is one that generates a high voltage using resonance characteristics to light a cold cathode fluorescent tube or the like, and is used for a backlight of a liquid crystal display or the like. As the screen of a liquid crystal display becomes larger, it is necessary to light a plurality of cold cathode fluorescent tubes in parallel.

  JP, 2003-309026, A (patent documents 3) etc. are indicated as an inverter transformer for lighting a plurality of discharge tubes. This uses an inverter transformer having two secondary windings coupled to one primary winding, and lights the discharge tubes respectively connected to the two secondary windings. Japanese Patent Application Laid-Open No. 2005-276919 (Patent Document 4) includes an auxiliary winding for adjusting the amount of magnetic flux acting on the secondary winding in order to prevent variations in luminance between the two discharge lamps. Have been disclosed.

In an inverter module using high voltage, when an abnormality occurs in a load or a circuit, a higher voltage than expected is generated and there is a risk of causing an accident such as smoke. Therefore, it is necessary to mount a protection circuit for detecting an output voltage and detecting the output voltage when an abnormal voltage (high voltage) occurs to shut down the circuit and stop oscillation. The detection methods are roughly classified into the following three methods. Generally, the method (1) is adopted.
(1) A high voltage capacitor is connected to a transformer that generates a high voltage, and the divided voltage is detected. In this case, the high voltage capacitor is also used as a secondary side resonance capacitor.
(2) A detection coil (insulated transformer) is mounted, and a high voltage is stepped down and detected as a low voltage output.
(3) A high voltage resistance is mounted and the divided voltage is detected.

  In the method as described above, a detection component is required for each output, and an insulation distance between the high pressure portion and the low pressure portion is also required, so that the complexity and size cannot be avoided. Therefore, it has been considered to use a part of the winding of the inverter transformer as a detection element. For example, in Japanese Patent Laid-Open No. 2003-309023 (Patent Document 1), in order to detect a voltage generated in the secondary winding, a voltage detection winding is provided separately from the secondary winding. It is disclosed that a tap is formed and the output is drawn out to the side where the primary terminal is disposed. Such a method is also described in Japanese Patent Application Laid-Open No. 2007-141752 (Patent Document 2), which discloses that a secondary winding is divided to obtain a low voltage for abnormality detection to control an oscillation circuit. Yes. However, this does not describe the structure of the transformer.

JP 2003-309023 A JP 2007-141752 A JP 2003-309026 A JP 2005-276919 A

  In the case of using a part of the winding of the inverter transformer as described above, the connection of the winding becomes complicated, the number of man-hours increases, and the problem of deterioration in reliability arises. The present invention makes it possible to reduce the cost by eliminating the need for special parts for detection, and also to reduce the size of the unit by enabling space saving.

  The present invention solves the above problem by improving the arrangement of windings and terminals of an inverter transformer. That is, a plurality of bobbins, a bobbin having a collar portion in which terminal pins are planted between and between both ends, a core that is partially inserted into the bobbin to form a magnetic circuit, and wound around these bobbins 1 In an inverter transformer having a secondary winding and a secondary winding, the primary winding is wound around the central winding frame, and the secondary windings are wound around the winding frames on both sides thereof. A part of the primary winding side of the winding is a detection winding, and the detection output of the detection winding is obtained from the tap of the secondary winding.

  According to the present invention, a special element is not required, and the transformer itself can have a detection function, thereby enabling cost reduction and improving the space factor. It is only necessary to use a coil or transformer tap forming technique, and high-voltage and low-voltage insulation is facilitated, and the terminals and windings can be connected in the shortest distance, thereby improving reliability.

Circuit diagram showing an embodiment of the present invention The circuit diagram which shows the example which uses the inverter transformer by this invention

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing an embodiment of the present invention. A so-called horizontal inverter transformer uses a bobbin divided into three winding frames by a ridge. The primary winding 13 is wound around the central winding frame among the three winding frames, and the ends thereof are connected to terminal pins 27 and 28 that are planted on the right end sides of the two central ribs. Generally, since the number of turns of the primary winding is small, a relatively thick wire is used.

  Two secondary windings 11 and 12 are wound around both ends of the three winding frames with the primary winding interposed therebetween. Since this secondary winding requires a large number of turns in order to obtain a high step-up ratio, a very thin wire is used, and in order to improve the withstand voltage, it is common to provide a partition on the winding frame and to divide the winding. Is. The terminals of the secondary windings are respectively connected to terminal pins that are implanted on the left end side of the ridges that sandwich the secondary winding.

  The secondary winding is used such that the terminal pin on the primary winding side is grounded so that the side far from the primary winding is high and the side close to the primary winding is low. That is, in the figure, the terminal pins 21 and 26 are connected to the terminals on the high voltage side of the secondary winding, and the terminal pins 23 and 24 are connected to the terminals on the low voltage side of the secondary winding. In the present invention, in order to use a part of the primary winding side of the secondary winding as the detection winding, the tap is drawn from a position close to the terminal on the low voltage side and connected to the terminal pins 22 and 25. The section of the secondary winding that is divided and wound closest to the primary winding may be the detection winding.

  By adopting the above structure, the secondary winding is disposed on both sides of the primary winding, and the high-voltage side of the secondary winding is located far from the primary winding. The detection winding is disposed as a low-voltage winding at a position closest to the primary winding. The end of the winding is also connected to the primary winding on the right side and the secondary winding on the left side, and the high-voltage terminal and the low-voltage terminal on the secondary side are connected to terminal pins installed in separate bushes. The end of each winding can be connected to the terminal pin with the shortest distance.

  In contrast to the secondary winding that generates a high voltage, the detection winding can be lowered by lowering the turn ratio. For example, when a high voltage of 2000V is generated, if the turn ratio is 400: 1, the voltage generated in the detection winding is 5V, and inexpensive low-voltage components can be used. In addition, since the secondary winding and the detection winding are connected in series and are part of the same winding, the voltage does not fluctuate due to factors other than the turns ratio, and accurate voltage detection is possible. .

  When used as an inverter transformer, a magnetic core is inserted into a bobbin and connected to an external core to form a magnetic loop to couple the primary and secondary windings. The terminal pin to which the winding terminal is connected is mounted on the wiring board to constitute an inverter module.

  FIG. 2 shows a circuit example using the inverter transformer according to the present invention. In FIG. 2, portions connected to the terminal pins of FIG. Both ends of the primary winding are connected to terminals 27 and 28, connected to a switching circuit, and intermittently turned on and off. By this operation, a high voltage output is generated in the secondary winding, and the two discharge tubes 2 connected to the two secondary windings are turned on. Here, the terminals 21 and 26 have a high voltage, and the terminals 23 and 24 have a low voltage by being grounded. The winding tap terminals 22 and 25 provided on the low voltage side are input to the voltage detection circuit, and when the detection output becomes higher than a certain value, an oscillation stop signal is output to the control IC to operate the transformer. Stop. With such a circuit configuration, the operation can be stopped if any of the discharge tubes has an abnormality.

  In the above example, an example of a 1-input, 2-output inverter transformer has been described. However, the present invention can be applied to a plurality of outputs such as 1-input, 4-output.

  The inverter transformer according to the present invention can be widely used for a liquid crystal television using a large liquid crystal screen, a navigation system, an inverter unit of an amusement device backlight, and the like.

11, 12: Secondary winding
13: Primary winding
14, 15: Detection winding
21 to 26: Terminal pin for secondary winding (detection winding)
27, 28: Terminal pin for primary winding

Claims (2)

A bobbin having a plurality of reels, a bobbin between which and at both ends have terminal pins implanted, a core that is inserted into the bobbin to form a magnetic circuit, and a primary winding wound around these bobbins In an inverter transformer comprising a wire and a secondary winding,
The primary winding is wound around the central winding frame, and the secondary windings are wound around the winding frames on both sides,
A part of the primary winding side of each secondary winding is used as a detection winding, and the detection output of the detection winding is obtained from the tap of the secondary winding ,
The end of the primary winding is connected to a terminal pin implanted on one side in a direction perpendicular to the bobbin winding axis of the bobbin collar, and the end of the secondary winding and the detection winding are on the opposite side Connected to the terminal pins implanted in the
The inverter transformer is further characterized in that the terminal of the secondary winding and the terminal of the detection winding are connected to terminal pins installed in separate ridges .   The winding frame of each secondary winding is divided into a plurality of parts, and the winding of the part wound around the primary winding side section of each secondary winding is the detection winding. The inverter transformer according to claim 1.

Images