JP4021931B1 - High frequency step-up transformer for fluorescent tubes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency step-up transformer for a fluorescent tube for lighting a plurality of fluorescent tubes arranged in parallel used as a backlight of a liquid crystal display panel.
[Solution]
In the present invention, a primary coil 21 for input and a plurality of secondary coils 22 for output are wound around one main magnetic circuit loop, the fluorescent tubes 40 having variations in the discharge start voltage are lit in parallel, and the discharge is started. This is a fluorescent tube high-frequency step-up transformer 13 characterized in that shunt magnetic bodies 26, 27, and 28 are attached to the respective secondary coils 22 in order to absorb the voltage difference between the voltage and the lighting voltage. With the addition of the magnetic materials for shunting 26, 27, and 28, the difference between the discharge start voltage and the lighting voltage is absorbed by the shunt magnetic flux inductance that is equivalently generated in series with each output, and a large number of parallel lighting is performed with a simple configuration. The current variation between the outputs is reduced.
[Selection] Figure 1

Description

  The present invention relates to a fluorescent tube high-frequency step-up transformer for lighting a plurality of fluorescent tubes arranged in parallel used as a backlight of a liquid crystal display panel.

  In recent large-screen liquid crystal display panels, a large number of fluorescent tubes are arranged in parallel on the back of the panel for backlighting. Multiple fluorescent tube high-frequency step-up transformers for lighting these fluorescent tubes at high frequency and high voltage are also required, resulting in increased mounting area, reduced reliability, and uneven brightness due to current variations in the fluorescent tubes arranged in parallel. Or, there is a problem such as complication of a lighting circuit by adding a balance circuit or the like in order to reduce current variation.

  In order to discharge and light a fluorescent tube used for a backlight of a liquid crystal display panel, it is necessary to apply a high voltage of high frequency of 1500 Vrms to 3000 Vrms and bring it into a discharge state. After the discharge starts, the fluorescent tube voltage is reduced from 1/2 to 1/3 of the discharge start voltage and enters a lighting state. When connecting multiple fluorescent tubes in parallel and lighting them, if the applied voltage is gradually increased, the discharge start voltage of each fluorescent tube will vary, so the discharge start is the most among the multiple fluorescent tubes connected in parallel. A fluorescent tube with a low voltage starts discharging and enters a lighting state. At that time, since the voltage at the connection point of the plurality of fluorescent tubes connected in parallel has decreased to the lighting voltage of the fluorescent tube already in the lighting state, the remaining fluorescent tubes cannot start discharging, and are in the lighting state. I can't enter. That is, when the fluorescent tubes connected in parallel are lit, only the fluorescent tube having the lowest lighting voltage is lit, and the remaining fluorescent tubes cannot be lit.

  First, an outline of a high-frequency step-up transformer for a fluorescent tube used for parallel lighting of backlight fluorescent tubes of a liquid crystal display panel will be described. FIG. 10 shows an example of a conventional multiple fluorescent tube lighting circuit. In FIG. 10, the DC input voltage 11D is applied to the inverter circuit 12 for converting the high frequency to the high voltage, the AC output on the secondary side of the inverter circuit 12 is applied to the primary side winding 21 of the fluorescent tube high frequency step-up transformer 13, The output voltage of the secondary winding 22 of the fluorescent tube high-frequency step-up transformer 13 is applied to the plurality of fluorescent tubes 40 via the impedance 14. The conventional multiple fluorescent tube lighting circuit will be described in detail below.

(1) Current-limiting impedance FIG. 11 shows an example of current-voltage characteristics of a fluorescent tube. 11, when gradually increasing the voltage applied to the fluorescent tube 40, the fluorescent tube becomes a discharge state in beyond the discharge starting voltage V _M, the load line by the limiting resistor that has entered between the power supply Lights up with the intersection P as the operating point. In order to absorb the voltage difference between the discharge start voltage V _M and the lighting voltage V ₀ , it is necessary to insert a current limiting impedance between the fluorescent tube and the power source. In order to avoid power loss, a reactance element such as a capacitor or an inductor is usually used as the current limiting impedance. As the multiple fluorescent tube lighting circuit, a secondary coil is equivalently obtained by using a ballast capacitor system using a capacitor as a reactance element and a leakage flux between a primary coil and a secondary coil of a high-frequency step-up transformer for a fluorescent tube as a reactance element. There is a leakage flux inductance method using a leakage flux inductance appearing in series with the output.

(2) Dispersion of discharge start voltage The discharge start voltage of the fluorescent tube varies from tube to tube. When a plurality of fluorescent tubes are connected in parallel and the voltage is gradually increased with a common current limiting impedance, the discharge starts first. the lowest fluorescent tube voltage V _M is turned on. At that time, since the voltage at the parallel connection point of the fluorescent tubes is lowered to the lighting voltage V ₀ , the other fluorescent tubes cannot enter the lighting state. Therefore, for the parallel lighting of the fluorescent tubes, it is necessary to put a current limiting impedance for each fluorescent tube as shown in FIG.

(3) Variation in lighting current of fluorescent tubes arranged in parallel If there is a variation in current between fluorescent tubes arranged in parallel, brightness unevenness occurs as a backlight, so the variation in current flowing in the tube must be suppressed as much as possible. .

  Hereinafter, the ballast capacitor method and the leakage flux inductance method, which are the parallel lighting methods of the fluorescent tubes for backlights of liquid crystal display panels, which are currently used mainly, will be described and their problems will be described.

FIG. 12 is a diagram showing a basic circuit of a parallel lighting ballast capacitor system. As shown in FIG. 12, this parallel lighting ballast capacitor system is an inverter circuit 12 that converts a DC input voltage 11D into a high frequency and a high voltage, a high frequency boost transformer for fluorescent tubes 13, a plurality of fluorescent tubes 40, and a high frequency boost for fluorescent tubes. The ballast capacitor 15 is inserted between the transformer 13 and each fluorescent tube 40 as a current limiting element. The output voltage of the fluorescent tube high-frequency step-up transformer 13 is set to a voltage higher than the maximum value of the variation in the discharge start voltage of the fluorescent tube. Assuming that the equivalent resistance in the lighting state of the fluorescent tube is R, the current I flowing through the fluorescent tube is I = I = the frequency of the output sine wave voltage of the inverter circuit is f, the capacitor capacity is C, and the output voltage of the high frequency boost transformer for fluorescent tube is Vo. 2πf · C · Vo / √ {(2πf · C · R) ² +1}
Given in.

The relationship between the ballast capacitor capacity 15 and the fluorescent tube current I is f = 50 KHz, R = 50 KΩ,
FIG. 13 shows the calculation result when Vo = 2000V. Since the capacitance variation of the high voltage capacitor used as the ballast capacitor is usually ± 10%, the current variation at this time is estimated to be about ± 10% from FIG. Since the power of the fluorescent tube is proportional to the square of the current, the variation in the fluorescent tube power is about ± 20%, and uneven brightness occurs in the backlight, which is not practically preferable. In this method, since the output voltage of the fluorescent tube high-frequency step-up transformer always outputs a voltage higher than the discharge start voltage of the fluorescent tube, the output voltage of the fluorescent tube high-frequency step-up transformer is 1 after the discharge start. There is also a problem that it is difficult to reduce the size of the high-frequency step-up transformer for a fluorescent tube in order to secure a withstand voltage, as compared with the leakage magnetic flux inductance method that lowers the lighting voltage to ½ to ３ or the method according to the present invention.

  FIG. 14 is a circuit diagram showing a leakage magnetic flux inductance method when the number of outputs is n. As shown in FIG. 14, the leakage magnetic flux inductance method includes an inverter circuit 12, a leakage magnetic flux type step-up transformer 13 having outputs of a plurality of secondary coils 22, and a plurality of fluorescent tubes 40. At this time, the leakage magnetic flux inductance that is equivalently generated in series with the secondary coil is used as the reactance element of the current limiting impedance. The leakage magnetic flux inductance method includes a magnetic flux parallel coupling type leakage magnetic flux inductance method in which a magnetic flux generated by a primary coil is supplied in parallel to a plurality of secondary coils, and a magnetic flux series coupling type leakage magnetic flux inductance method that is supplied in series. The magnetic flux parallel coupling type leakage flux inductance method has been used as a multi-output high-frequency step-up transformer for fluorescent tubes. However, the magnetic flux series coupling type leakage flux inductance method has a problem in starting and lighting multiple connected fluorescent tubes. There is no track record as a multi-output high-frequency step-up transformer.

  FIG. 15 is a diagram showing an example of the structure of a high-frequency step-up transformer for a fluorescent tube of a parallel-coupling-type leakage flux inductance method with two outputs. The magnetic flux Φ1 generated in the primary side magnetic body 23 by the current I1 flowing through the primary coil 21 is partly linked to the primary side magnetic body 23 without interlinking with the secondary coil 22 by the magnetic flux return magnetic body 24 that circulates the leakage magnetic flux. The remaining magnetic flux flows into the plurality of secondary-side magnetic bodies 25, and the magnetic flux is divided into each of the secondary coils 22 wound around each secondary-side magnetic body 25 (25a, 25b). An induced voltage proportional to is generated.

FIG. 16 is a diagram illustrating an equivalent magnetic circuit of a magnetic flux parallel coupling type leakage flux inductance method with n outputs. In this circuit, the magnetic flux flowing in the magnetic material is regarded as a current, and the magnetic resistance is regarded as an electric resistance, and is written in the same manner as the electric circuit. In FIG. 16, V1 is the input voltage, I1 is the input current, and the frequency of the sine wave is f and the time is t. V1 = Va · sin (2πf · t)
I1 = Ia · sin (2πf · t−π / 2)
And V2n is the output voltage, I2a, I2b,... I2n is the output current, N1 is the number of turns of the primary coil 21, N2 is the number of turns of the secondary coil 22, and R is the load of the output circuit. Resistance, Vm1 is the magnetomotive force of the primary coil,
Vm1 = N1 ・ I1
Given in. Vm2 (Vm2a, Vm2b,... Vm2n) is a magnetomotive force that generates a magnetic flux from the secondary side to the primary side when an output current flows through the output coil.
Vm2 = N2 ・ I2
Given in.

  Rm2 (Rm2a, Rm2b,... Rm2n) is the magnetic resistance for each output section of the secondary side magnetic body, Rm3 is the magnetic resistance of the magnetic flux recirculation magnetic body, Φ1 is the magnetic flux generated by Vm1, ... Φ2n) is a magnetic flux generated by each Vm2. Further, the ratio of the magnetic flux flowing into the secondary magnetic body out of the magnetic flux Φ1 generated by the primary coil is the coupling coefficient K1, and conversely the magnetic flux flowing into the primary magnetic body out of the magnetic flux Φ2 generated by the magnetomotive force Vm2 of the secondary coil. Let the ratio be the coupling coefficient K2.

At this time, the peak value Va of the input voltage, the peak value Ia of the input current necessary for securing the open output voltage Vo when the load resistor R is not connected, the peak value Ia of the primary current to prevent magnetic saturation. The cross-sectional area S is as follows when the number of parallel outputs is n. However, Rm0 is the total magnetic resistance viewed from the primary coil, and Bm is the saturation magnetic flux density of the magnetic material.
Va = N1 ・ Vo / K1 ・ N2
Ia = Rm0 · Va / 2πf · N1 ²
S = Vo / 2πf, K1, N2, Bm
In the above formula, N1 = 20 (turn), N2 = 1500 (turn), Vo = 2000V0-p, Rm0 = 2 × 10 ⁶ (1 / Henry), Rm2 = 1 × 10 ⁶ (1 / Henry), Rm3 = FIG. 17 shows the relationship between the number of outputs n calculated as 10 × 10 ⁶ (1 / Henry), f = 50 kHz, Bm = 0.3 (Tesla) and the peak value Va of the input voltage. The relationship of Ia is shown in FIG. 18, and the relationship between the output number n and the required cross-sectional area S is shown in FIG.

The magnetic flux required for one secondary coil output to secure the secondary open circuit output voltage Vo is Vo / 2πf · N2.
In the magnetic flux parallel coupling type multi-output system with n outputs, the primary side needs a magnetic flux amount obtained by dividing n times this by the coupling coefficient K1 from the primary side to the secondary side. Magnetic flux will be concentrated. For this reason, the input voltage increases as shown in FIG. 17 and the primary coil current increases as shown in FIG. 18 or the primary magnetic cross-sectional area increases as shown in FIG. 19, resulting in a proportional to the square of the current. Fatal increase in conductor loss due to winding resistance of primary coil, increase in magnetic loss proportional to the square of magnetic flux density, or increase in size due to expansion of cross-sectional area of magnetic material to suppress magnetic saturation Defects occur.

  As described above, the magnetic flux parallel-coupled leakage flux inductance type high-frequency step-up transformer for a fluorescent tube for parallel lighting of a backlight fluorescent tube has various problems because the primary magnetic flux increases. In order to improve this, a magnetic flux series coupled leakage flux inductance method, which has been used as a general-purpose multi-output transformer in the past and has the feature that the magnetic flux does not concentrate on the primary side even if the number of outputs increases, is used as a high-frequency step-up transformer for fluorescent tubes. The problem in application is examined.

FIG. 20 shows an example of the configuration of a high-frequency step-up transformer for a leakage flux inductance type fluorescent tube of the magnetic flux series connection type in the case where the number of outputs is n. In FIG. 20, a magnetic flux Φ1 is generated in the primary side magnetic body 23 by the current I1 flowing through the primary coil 21 by the input voltage V1. This magnetic flux Φ1 flows into the magnetic flux recirculation magnetic body 24, and in order to generate leakage magnetic flux inductance, a part (1-K) · Φ1 recirculates to the primary side, and the magnetic flux K · Φ1 flows into the secondary side magnetic body 25. To do. Here, K is a coupling coefficient between the primary coil and the secondary coil. The magnetic flux K · Φ1 is coupled to the first to nth secondary coils 22 (22a, 22b,... 22n) wound in series, and the output voltage V2 (V2a, V2b,... V2n) are generated. The peak value Vo of each output voltage V2 when no load resistance is connected to the output terminal is N1 for the number of turns of the primary coil and N2 for the number of turns of the secondary coil.
Vo = K ・ N2 ・ V1 / N1
It becomes.

When the load resistor R is connected only to the output terminal of the first secondary coil 22a, the current I2a flows through the connected load resistor R, and this current flows through the first secondary coil. A magnetic flux Φ2 is generated in a direction opposite to the magnetic flux K · Φ1 from the primary coil 21. The magnetic flux Φ2 in the reverse direction is returned to the secondary side by (1−K) · Φ2 by the magnetic flux returning magnetic body 24, the remaining K · Φ2 flows into the primary side magnetic body, and the primary side magnetic body magnetic flux is transferred from Φ1. Move in the direction of decreasing to Φ1-K · Φ2. At this time, the basic relational expression of the magnetic flux Φ and the coil voltage V of the number N of turns Φ = (1 / N) ∫V · dt
Therefore, if N and V are constant, Φ is always constant, so that the primary magnetic flux Φ10 at no load and the primary magnetic flux Φ1-K · Φ2 at the same load are equal Φ10 = Φ1-K・ Φ2 = (1 / N1) ∫V1 ・ dt
Relationship is maintained.

Therefore,
Φ1 = Φ10 + K ・ Φ2
Thus, the increase K · Φ2 from the time of no load is compensated by the increase in the current I1 flowing through the primary coil. This increase K · Φ2 is a magnetic material for refluxing magnetic flux, and (1-K) · K · Φ2 returns to the primary side, and the remaining K ² · Φ2 flows into the secondary side. As a result, the magnetic flux of the secondary side magnetic body decreases by (1−K ² ) · Φ2 with respect to the initial state where no load is connected. Since this decrease is the same in the second and subsequent secondary coils in which no load resistance is connected to the output terminal, the open output voltage at the no-load output terminal also decreases.

Generally, the peak value Vo of the output voltage when the load resistance R is connected to n output terminals is
Vo = K · N2 · R · Va / n · L2R · N1 · √ {(R / n · L2R) ² + (2πf) ² }
It becomes. Here, it is assumed that the frequency f and time t are V1 = Va · sin (2πft), and the leakage flux inductance on the secondary side is L2R. In FIG. 21, when Va = 30V, f = 50KHz, N1 = 20 (turn), N2 = 1500 (turn), K = 0.75, R = 50KΩ, and L2R = 225mH, the load resistance is connected from the above equation. The result of having calculated the relationship between the output number n and the peak value Vo of the output voltage is shown. From FIG. 21, it can be seen that the output voltage of 1700 V when all the loads are open decreases to 1000 V when the load is connected to one output.

On the other hand, in recent years, a central leg portion 113 is disposed between two side leg portions 111 and 112 as shown in FIG. 22 and these three leg portions are sandwiched between two connecting portions 115 to form a magnetic circuit. A core portion 101, a primary winding 102 provided on one side leg portion 112, and a secondary winding 103 provided on a central leg portion 113 are provided, and gaps 111A are provided in the side leg portions 111 and 112, respectively. 112A are formed so that one end face 112A of the primary winding 102 is positioned at the end of the one side leg portion and the length of the central leg portion 113 is set so that the primary winding 102 is A leakage flux inductance type transformer having a structure in which a primary winding 102 and a secondary winding 103 are arranged so as to face the secondary winding 103 is disclosed (Patent Document 1). According to this leakage flux inductance type transformer, the primary winding 102 and the secondary winding 103 are arranged with respect to the core portion 101, and the primary winding 102 and the secondary winding 103 are appropriately connected. As a result of the positional relationship for obtaining the leakage magnetic flux inductance, a ballast capacitor is not required and good inverter characteristics can be obtained.
JP 2004-111417 A

  However, the above ballast capacitor system and leakage flux inductance system have the following problems. First, in the ballast capacitor system in which a capacitor is placed between one output terminal and a plurality of fluorescent tubes as a current limiting reactance element, the voltage at the output terminal of the fluorescent tube high-frequency step-up transformer is the discharge start voltage of the plurality of fluorescent tubes having variations. The voltage is set to a higher voltage than that, and this voltage is always output even after each fluorescent tube is lit. In general, the discharge start voltage of a fluorescent tube is two to three times higher than the lighting voltage, and the high frequency boost transformer for fluorescent tubes always outputs this high voltage, and the high frequency boost transformer for fluorescent tubes is downsized to ensure withstand voltage. In addition, there are many problems in terms of ensuring reliability because there is a large restriction and the probability of dielectric breakdown due to high voltage increases.

  The current flowing through each fluorescent tube is obtained by dividing the output terminal voltage by the series impedance of the equivalent resistance of the capacitor and fluorescent tube. The capacitance value of the high voltage capacitor used in this application usually has an error of ± 10%. For this reason, the variation of the current value becomes large, and the luminance unevenness of the fluorescent tube backlights arranged in parallel becomes a problem.

  Next, in the leakage flux inductance method using the leakage flux inductance by the leakage flux type transformer as the current limiting element, a plurality of secondary coils are wound around the magnetic flux generated in the primary magnetic body due to the current flowing in the primary coil. In order to suppress variations in the output current value flowing in the secondary side coil, the magnetic field of each secondary side magnetic body is shunted to a plurality of secondary side magnetic bodies that form parallel shunt paths for magnetic flux flowing from the primary side. The resistance must be equal and the amount of magnetic flux to be shunted must be uniform. For this reason, it is necessary to make the magnetic resistance proportional to the magnetic path length / cross-sectional area of the magnetic body equal for each output magnetic circuit, which is an index of the difficulty of flowing the magnetic flux. In a high-frequency step-up transformer for fluorescent tubes of this application, which is often rectangular and thin, it is difficult to provide a large number of output magnetic circuits with the same magnetic resistance. The upper limit of the number is limited to about 4, and a large number of high-frequency step-up transformers for fluorescent tubes are required to light up 10 to 30 fluorescent tubes that are normally required in a large liquid crystal display panel.

  In addition, in the magnetic flux parallel coupling type leakage flux inductance method, the sum of the magnetic flux flowing through each output magnetic circuit wound with the secondary coil is concentrated on the primary side magnetic body wound with the primary coil. It is necessary to increase the generated voltage by increasing the coil drive voltage.

  Furthermore, the primary magnetic body through which a large magnetic flux flows must have a large magnetic circuit cross-sectional area as a countermeasure against magnetic saturation, resulting in an increase in the shape of the high-frequency step-up transformer for a fluorescent tube, or a magnetism proportional to almost the square of the magnetic flux density. There is also a disadvantage that body loss increases extremely.

  In addition, in the magnetic flux series coupled leakage flux inductance method, when a fluorescent tube with a variation in the discharge start voltage is connected to each output terminal of the high-frequency step-up transformer for the fluorescent tube, the fluorescent tube with the lowest discharge start voltage is turned on. Since the output voltage is greatly reduced when entering, the other fluorescent tubes cannot exceed the discharge start voltage and have a fatal defect that they cannot enter the lighting state.

  In view of the above-mentioned problems, the present invention is capable of lighting a large number of fluorescent tubes in parallel with a simple structure, with less output current variation, high lighting efficiency, and excellent characteristics such as light weight and small shape. An object of the present invention is to provide a high-frequency voltage step-up transformer for a fluorescent tube.

In order to solve the above-described problems, a high-frequency step-up transformer for a fluorescent tube according to a first aspect of the present invention includes a primary side magnetic body wound with a primary coil and a closed magnetic flux in series with a plurality of secondary coils and the primary side magnetic body. and the secondary side magnetic member forming a magnetic circuit, covers a portion of the secondary coil, both ends are composed of a partial diversion magnetic body formed so as to come into contact with the secondary magnetic member, a plurality of secondary Each of the coils is connected to a fluorescent tube, and the magnetic flux passing through the secondary side magnetic body is shunted by the shunting magnetic body.

According to a second invention, in the first invention, the secondary side magnetic body is formed in a U shape, and both ends thereof are formed so as to be joined to the primary side magnetic body, and the primary side magnetic body and the secondary side magnetic body are formed. characterized that you form a closed magnetic flux magnetic circuit in series by the body.

In a third aspect based on the first aspect, the secondary side magnetic body is composed of two secondary side magnetic bodies for coils formed in a rod shape and a magnetic body for forming a closed magnetic circuit formed in a rod shape, One end of each coil secondary side magnetic body is joined to the primary side magnetic body, and both ends of the closed magnetic path forming magnetic body are joined to the other end of the coil secondary side magnetic body.

A fourth invention, in the third invention, the cross-sectional surface is made form with shaped magnetic material co, U-shaped one secondary coil wound towards the coil a magnetic material of the magnetic body The secondary side magnetic body, the magnetic body on which the other secondary coil of the U-shaped magnetic body is not wound is the shunting magnetic body, and the primary side magnetic body and the U-shaped magnetic body coil A closed magnetic flux magnetic circuit is formed by the secondary side magnetic body portion and the closed magnetic path forming magnetic body, and the magnetic flux passing through the secondary side magnetic body portion for the coil is generated by the other shunt magnetic body portion of the U-shaped magnetic body. It is characterized by shunting .

A fifth invention, in the third invention, the cross-sectional surface is made form a magnetic material E-shaped, the ga across the E-shaped magnetic body and the secondary side magnetic coil, E-shaped magnetic The center branch of the body is a shunting magnetic body, and a closed magnetic flux magnetic circuit is formed by the primary side magnetic body, the secondary side magnetic body portion of the E-shaped magnetic body, and the closed magnetic path forming magnetic body, and the E-shaped magnetic The magnetic flux passing through the secondary magnetic body portion for the coil is shunted by the magnetic body portion for branching of the branch in the center of the body.

According to the first invention, the high-frequency step-up transformer for a fluorescent tube includes a primary side magnetic body wound with a primary coil, and a plurality of secondary coils wound around the primary side magnetic body to form a closed magnetic flux magnetic circuit in series. The secondary side magnetic body and a part of the secondary coil are covered, and both ends of the secondary side magnetic body are formed to be joined to the secondary side magnetic body. The plurality of secondary coils are respectively connected to the fluorescent tube. Since the magnetic flux passing through the secondary side magnetic material is shunted by the shunting magnetic material, even when the fluorescent tube with the lowest lighting voltage is lit when the fluorescent tubes connected in parallel are lit The remaining fluorescent tubes can be lit reliably.

According to the second invention, the secondary side magnetic body is formed in a U-shape, and both ends thereof are formed so as to be joined to the primary side magnetic body, and are connected in series by the primary side magnetic body and the secondary side magnetic body. Runode to form a closed magnetic flux magnetic circuit, can provide compact, high efficiency, high current accuracy fluorescent tubes for high frequency step-up transformer with a simple structure.

According to the third invention, the secondary magnetic member is composed of a secondary side magnetic member for the two coils to be formed into a rod, which is formed in a rod shape closed magnetic path forming magnetic body, two for each coil One end of the secondary side magnetic body is joined to the primary side magnetic body, and both ends of the closed magnetic path forming magnetic body are joined to the other end of the secondary side magnetic body for the coil . A high-current high-frequency step-up transformer for fluorescent tubes can be provided.

The According to the fourth invention, the cross-sectional surface is made form with shaped magnetic material co, one of the secondary coils wound towards magnetic secondary side coil of the shaped magnetic material co The magnetic body that is not wound with the other secondary coil of the U-shaped magnetic body is the magnetic body for shunting, and the primary side magnetic body and the secondary side for the coil of the U-shaped magnetic body A closed magnetic flux magnetic circuit is formed by the magnetic body portion and the closed magnetic path forming magnetic body, and the magnetic flux passing through the secondary magnetic body portion for the coil is shunted by the other shunt magnetic body portion of the U-shaped magnetic body . A high-frequency step-up transformer for a fluorescent tube with a simple structure, easy assembly, small size, high efficiency, and high current accuracy can be provided.

According to the fifth invention, the cross-sectional surface is made form a magnetic material E-shaped, the ga across the E-shaped magnetic body and the secondary side magnetic coil, the central E-shaped magnetic substance The branch path is a magnetic body for shunting, and a closed magnetic flux magnetic circuit is formed by the primary side magnetic body, the secondary side magnetic body portion of the E-shaped magnetic body, and the closed magnetic path forming magnetic body, and the center of the E-shaped magnetic body and the secondary side magnetic secondary coil to shunt the magnetic flux passing through the secondary magnetic portion coil is wound by partial diversion magnetic portion of ga, the shunt magnetic body for covering a portion of the secondary coil The cross section is integrally formed as an E-shaped magnetic body, the branch at both ends of the E-shaped magnetic body is a secondary magnetic body, and the central branch of the E-shaped magnetic body is a branching magnetic body A closed magnetic flux magnetic circuit is formed by the primary side magnetic body, the secondary side magnetic body portion of the E-shaped magnetic body and the magnetic body for forming a closed magnetic path, and the E-shaped magnetic body Magnetic flux passing through the secondary magnetic part is shunted by the magnetic part for shunting in the central branch, so that the high-frequency step-up transformer for fluorescent tubes has a simple structure, easy assembly, small size, high efficiency, and high current accuracy. Can provide.

First embodiment.
FIG. 1 is a schematic diagram when the number of outputs is n in the high-frequency step-up transformer 13 for fluorescent tubes of the present invention. In order to improve the above-mentioned defects while utilizing the characteristics of the conventional magnetic flux series coupled type leakage flux inductance type step-up output transformer, the present invention, as shown in FIG. 1, a primary coil 21 and secondary coils 22 (22a, 22b). 22n), a primary side magnetic body 23 around which the primary coil 21 is wound, a secondary side magnetic body 25 around which the secondary coil 22 is wound, and a portion of the secondary coil 22 that covers a part of the secondary side magnetic body 23 It is comprised from the magnetic material 26 for shunting (26a, 26b, ... 26n) comprised so that it may join to the secondary side magnetic body 25. FIG.

In FIG. 1, the magnetic flux Φ1 generated in the primary side magnetic body 23 by the current I1 flowing through the primary coil is a junction P1 between the secondary side magnetic body 25 and the shunting magnetic body 26a around which the first secondary coil 22a is wound. The magnetic resistance Rm3 of the shunt magnetic body 26a corresponding to the magnetic resistance Rm2 of the secondary side magnetic body between the junction points P1 and P2 causes the magnetic flux of K1 · Φ1 to be applied to the secondary side magnetic body, and the shunt magnetic body. (1−K1) · Φ1 flows through Note that Rm2 and Rm3 are shown in FIG.
Here, the magnetic flux shunt coefficient K1 is
K1 = Rm3 / (Rm2 + Rm3)
It is expressed by the following formula.

  The magnetic flux K1 · Φ1 flowing through the secondary side magnetic body 25 of the first secondary coil 22a and the magnetic flux (1−K1) · Φ1 shunted to the shunt magnetic body 26a at the upper junction P1 are again at the lower junction P2. It joins, becomes Φ1, and flows into the junction point P3 of the second secondary coil 22b. In this way, if there are n secondary coils, the diversion and merging are repeated at the junction of each secondary side magnetic body and the diversion magnetic body, and then returned to the primary side magnetic body.

  FIG. 2 is a magnetic circuit diagram of the fluorescent tube high-frequency step-up transformer of FIG. In FIG. 1, the magnetic resistance of the primary side magnetic material is Rm1, the magnetic resistance of one section from P1 to P2 of the secondary side magnetic body is Rm2, the magnetic resistance of the same section of the shunting magnetic body is Rm3, and the input voltage is V1 (= Va · sin (2πft)), Va is the maximum value of the input voltage, f is the frequency of the input voltage, I1 is the current flowing through the primary coil, N1 is the number of turns of the primary coil, and Φ1 is the magnetic flux generated by the primary coil. , The magnetic flux shunting coefficient at each junction of the secondary side magnetic body and the shunting magnetic body is K1, the number of turns of the secondary coil is N2, the output side load resistance is R, and the output current of the secondary coil is I2 and I2. The magnetomotive force Vm2 in the reverse direction generated in the secondary side magnetic body directly below the secondary coil, and the magnetic flux generated thereby is Φ2.

First, when all the output terminals of the secondary coils are open, each secondary coil is linked to the magnetic flux K1 · Φ1 flowing in the secondary side magnetic body, so the output terminal voltage V2 is V2 = N2 · d (K1 · Φ1). ) / Dt
V1 = N1 · d (Φ1) / dt
From the relational expression, V2 = K1, N2, Va, sin (2πf, t) / N1
It becomes.

Also, from this relationship, the generated magnetic flux Φ1 of the primary coil necessary for outputting the output voltage V2 necessary for starting the fluorescent tube discharge to the secondary coil output terminal is V2 = Vo · sin (2πf · t), and the above equation is Φ1 Φ1 ＝ Vo / 2πf ・ K1 ・ N2
Given in. As described above, in the high-frequency step-up transformer for a multi-output fluorescent tube according to the present invention, since the secondary coil and the magnetic flux are coupled in series, even if all the n secondary coils output Vo, the primary side magnetic flux is one. It will be the same as in the case of.

Next, when the load resistance R is connected only to the output terminal of the first secondary coil 22a, the output voltage V2a of the first secondary coil 22a and the output voltage V2b of the second secondary coil 22b in the open state are connected. Calculate First, a current I2a flows through the first secondary coil 22a, and this current causes a magnetomotive force N2 · in the direction opposite to the magnetic flux K1 · Φ1 flowing from the primary side into the secondary side magnetic body immediately below the first secondary coil 22a. I2 is generated, and the total magnetic resistance seen from the magnetomotive force generation point is Rms, and the magnetic flux Φ2 by this magnetomotive force is
Φ2 ＝ N2 ・ I2a / Rms
Occurs in the direction of decreasing K1 · Φ1. Φ2 is a junction P1 between the secondary side magnetic body and the shunt magnetic body of the first secondary coil 22a, and the magnetic shunt ratio at the P1 point is K2, and the primary side magnetic body is K2 · Φ2, and the shunt magnetic body is (1-K2) ・ Divert to Φ2.

K2 is the magnetic resistance Rm3 of the magnetic material for shunting, the magnetic resistance Rm1 of the primary side magnetic material, the magnetic resistance Rm2 of the secondary side magnetic material of the second to n-th secondary coils 22, and the magnetic resistance of the magnetic material for shunting. The magnetic resistance of the sum of the parallel magnetic resistances of the resistor Rm3 is given by the following equation as Rmp.
K2 = Rm3 / (Rm1 + Rmp + Rm3)
In this way, the magnetic flux generated by the primary coil is shunted by the shunting magnetic material, and K1 · Φ1 is linked to the secondary coil. Similarly, only K2 · Φ2 of the magnetic flux Φ2 generated by the secondary coil is the same. By interlinking with the primary coil 21, an inductance is equivalently inserted in series with the output of each secondary coil. This inductance is generated by shunting the magnetic flux for each output, and is here referred to as a shunt magnetic flux inductance Lb.

The output voltage V2a of the first secondary coil is V1 V1 = Va · sin (2πf · t)
The relational expression of the primary side and the secondary side V1 = N1 · d (Φ1−K2 · Φ2) / dt
V2a = N2 * d (K1 * Φ1-Φ2) / dt
I2a = V2a / R
Φ2 = N2 ・ I2a / Rms = (N2 ・ N2 / R ・ Rms) ・ d (K1 ・ Φ1−Φ2) / dt
, The peak value Voa of V2a is given by the following equation.
Voa = K 1 · N 2 · R · Va / N 1 · Lb · √ {(R / Lb) ² + (2πf) ² }

Next, the output voltage V2b of the second secondary coil 22b whose output terminal is open is calculated. The magnetic flux of the secondary side magnetic body just below the second secondary coil 22 is K1 · Φ1 from the primary coil, and the reverse side magnetic flux Φ2 generated by the first secondary coil is the primary side magnetic body 23. The components K2 and .PHI.2 to be shunted from the primary side magnetic body 23 to the nth output section... The third output section and the secondary side magnetic body 25 of the second secondary coil 22b and the shunt magnetic body. 26, the magnetic flux obtained by multiplying the magnetic flux shunt ratio K1 between the secondary side magnetic body and the shunting magnetic body in each output section is shunted to the secondary side magnetic body at P4. K1, K2, and Φ2 flow into the secondary side magnetic body directly below the second secondary coil in a direction that reduces the magnetic flux K1 and Φ1 from the primary coil. Accordingly, the output voltage V2b of the second secondary coil 22b is V2b = N2 · d (K1 · Φ1−K1 · K2 · Φ2) / dt
Therefore, when Φ1 and Φ2 obtained by the calculation of Voa are substituted into the above equation, the peak value Vob of V2b is Vob = K1, N2, Va, N1
It becomes.

  This is the same as the equation when all outputs are open, so when one of the fluorescent tubes is turned on when multiple fluorescent tubes are loaded, the discharge has not started yet. This indicates that a voltage exceeding the discharge start voltage is applied to the fluorescent tube, and as a result, all the fluorescent tubes can enter the lighting state.

Next, the output voltage V2 on the secondary side when the load resistance R is loaded on the output terminals of all the secondary coils 22 is calculated. First, a current I2a flows through the first secondary coil 22a, and this current causes a magnetomotive force N2 · I2a in the opposite direction to the magnetic flux K1 · Φ1 flowing from the primary side into the secondary side magnetic body immediately below the first secondary coil 22a. The total magnetic resistance seen from the point of occurrence is Rms, and the magnetic flux Φ2 due to this magnetomotive force is Φ2 = N2 · I2 / Rms
Occurs in the direction of decreasing K1 · Φ1. Φ2 is a junction point P1 between the secondary side magnetic body 25 and the shunt magnetic body 26 of the first secondary coil 22a, and this flux shunt ratio is set to K2 for the input side magnetic body K2 · Φ2, and for the shunt magnetic body ( 1-K2) · Φ2 is shunted.

  Further, assuming that the load resistances R of all the outputs and K1, K2, and N2 are equal, the output voltages V2 and the output currents I2 of all the outputs are all equal, and the second second coil 22b is caused by the current flowing through the second secondary coil 22b. The magnetic flux Φ2 generated in the secondary side magnetic body 25 immediately below the secondary coil 22b is equal to the magnetic flux Φ2 generated by the first secondary coil, and the secondary side magnetic body 25 and the shunting magnetic body of the second secondary coil 22b. At the upper junction point P3 with 26b, K2 · Φ2 flows to the first secondary coil side, and (1-K2) · Φ2 branches to the magnetic material for shunting of the second secondary coil. The magnetic flux K2 · Φ2 flowing into the first secondary coil section is applied to the secondary side magnetic body at the lower junction P2 of the secondary side magnetic body and the shunting magnetic body of the first secondary coil. The current is divided into (1−K1) · K2 · Φ2 to Φ2 and the magnetic material for diversion, but again merges at the upper junction P1 and flows into the primary side magnetic material as K2 · Φ2.

Thus, the magnetic flux generated by the second secondary coil 22a to the n-th secondary coil 22n is
(n-1) ・ K1 ・ K2 ・ Φ2
Flows into the secondary side magnetic body 25 immediately below the first secondary coil 22a in a direction to reduce the magnetic flux K1Φ1 from the primary coil 21, so that the magnetic flux interlinked with the first secondary coil 22a is K1 · Φ1. −Φ2− (n−1) ・ K1 ・ K2 ・ Φ2
It becomes.

Therefore, in this case, the output voltage V2 and the output current I2 are V1 = N1 · d (Φ1−n · K2 · Φ2) / dt where V1 is the sine wave voltage described above.
V2 = N2 · d (K1 · Φ1-Φ2-(n-1) · K1 · K2 · Φ2) / dt
I2 = V2 / R
Φ2 = N2 / I2 / Rms
= (N2 / N2 / R / Rms) / d (K1 / Φ1-Φ2 + (n−1) / K1 / K2 / Φ2) / dt
, And the respective peak values Vo and Io are given by the following equations.
Vo = K1, N2, R, Va / N1, Lb, {{R / Lb) ² + (2πf) ² }
Io = K 1 · N 2 · Va / N 1 · Lb · √ {(R / Lb) ² + (2πf) ² }

  As described above, Lb in the above equation is a shunt magnetic flux that is equivalently generated in series with the output of the secondary coil 22 by shunting the magnetic flux of the secondary side magnetic body 25 by the shunt magnetic body 26. Inductance. From this result, it can be seen that the voltage and current at the time of lighting of the high-frequency step-up transformer for a fluorescent tube of this system are constant regardless of the number of outputs n.

From the above examination results, the high-frequency step-up transformer for a fluorescent tube according to the present invention is characterized by improving the following points which have been problems in the past.
Features (1)
Increasing the number of outputs n does not increase the magnetic flux of the primary side magnetic body.
As described above, in the high frequency step-up transformer for a magnetic flux parallel coupled type leakage flux inductance type fluorescent tube at n outputs, the amount of magnetic flux of the primary side magnetic material increases to n times that of a single case. In the case of a single high frequency step-up transformer for fluorescent tubes, the number of magnetic fluxes is the same regardless of whether the number is n or n, and even in the case of a multi-output high frequency step-up transformer for fluorescent tubes, the input voltage can be suppressed to the same level. The low input voltage means that the excitation current of the primary coil is small, and as a result, the conductor loss of the primary coil proportional to the square of the current can be greatly reduced. In addition, since the magnetic material loss proportional to the square of the magnetic flux density is greatly improved, a highly efficient fluorescent tube high-frequency step-up transformer can be realized. Furthermore, there is no need to increase the magnetic cross-sectional area in order to prevent magnetic saturation of the magnetic material, and a reduction in size and weight can be realized.

Features (2)
The output voltage and current do not depend on the number of outputs n.
In a conventional magnetic flux series coupled leakage flux inductance type high frequency step-up transformer that has been used as a general-purpose transformer, when one of the n outputs enters the lighting state, the other output voltage drops extremely, so the remaining fluorescent tubes Although it cannot light up, in the high-frequency voltage step-up transformer for fluorescent tubes of the present invention, each output operates regardless of whether other outputs are lit or not lit by the action of the magnetic material for shunting. Even in the case of exceeding 10, it is possible to light even a fluorescent tube arranged in parallel and having a variation in the discharge start voltage, and the lighting device can be reduced in size, reliability, and price.

Features (3)
Since the magnetic flux coupled to each output coil is common, the variation in output voltage and output current is extremely small. In the multi-output ballast capacitor system that branches n outputs by the capacitor, there is an output current value variation that is almost equal to the variation in the capacitance value of the capacitor. In addition, the primary coil is used in the high-frequency step-up transformer for the multi-output fluorescent tube. However, the magnetic resistance ratio of the secondary side magnetic body exceeding n = 10 is efficiently suppressed with a limited shape. This is difficult, and the output current varies greatly. In the fluorescent tube high-frequency step-up transformer according to the present invention, since each output is determined by a common magnetic flux passing through the secondary side magnetic body, variations in output voltage and output current can be suppressed.

  FIG. 3 is a schematic diagram of the case where the number of outputs is 4 in the fluorescent tube high-frequency step-up transformer 13 according to the first embodiment of the present invention. In the first embodiment, as shown in FIG. 3, a closed magnetic flux magnetic circuit is formed by the primary side magnetic body 23 and the secondary side magnetic body 25 formed in a U-shape. In the high frequency step-up transformer for a fluorescent tube of the first embodiment, a primary coil 21 is wound around a primary side magnetic body 23, and a secondary coil 22 (22a, 22b, 22c, 22d) is wound around a secondary side magnetic body 25. The shunting magnetic body 26 (26a, 26b, 26c, 26d) is attached so as to cover a part of the secondary coil 22. The shunting magnetic body 26 is formed in a U shape, the center portion covers the secondary coil 22, and the end portion is joined to the secondary side magnetic body 25. Generally, the primary coil 21 and the secondary coil 22 are fitted to the primary side magnetic body 23 and the secondary side magnetic body 25 in the state wound around the bobbin, respectively.

  FIG. 4 is a perspective view showing the structure of the fluorescent tube high-frequency step-up transformer 13 according to the first embodiment of the present invention. In FIG. 4, the end portion of the U-shaped secondary side magnetic body 25 is joined to both ends of the primary side magnetic body 23 to form a closed magnetic flux magnetic circuit. The primary coil 21 and the secondary coil 22 are respectively fitted to the primary side magnetic body 23 and the secondary side magnetic body 25 in a state of being wound around a bobbin. The center part of the shunting magnetic body 26 covers the secondary coil 22 from above the secondary coil 22, and both ends thereof are joined to the secondary side magnetic body 25 to form a magnetic flux shunt circuit.

  As described above, the high-frequency step-up transformer for multi-output fluorescent tubes using the shunt magnetic flux inductance method according to the present invention can be arranged in parallel and can efficiently light a plurality of fluorescent tubes with variations in the discharge start voltage, and at the time of load. Output voltage V2 is the magnetic flux shunt ratio K1 between the secondary side magnetic body and the shunt magnetic body, the secondary coil / primary coil turns ratio N2 / N1, the shunt flux inductance Lb, the load resistance R, the amplitude Va of the input voltage, It depends only on the frequency f and does not depend on the number of outputs n. This is different from the high-frequency step-up transformer for a magnetic flux parallel coupled leakage flux inductance type multi-output fluorescent tube having an upper limit on the number of outputs n, and it is possible to realize the parallel driving of fluorescent tubes exceeding n = 10 with one transformer, and Since the output is driven by a common constant magnetic flux that loops around the primary side magnetic body and the secondary side magnetic body, variation in output current can be extremely reduced.

  Further, since the amount of magnetic flux of the primary side magnetic body is constant regardless of the number of outputs n, the amount of magnetic flux of the primary side magnetic body increases as n increases as in the case of the parallel magnetic flux coupling type leakage flux inductance type multi-frequency fluorescent tube high-frequency step-up transformer. The cross-sectional area of the magnetic material can be reduced without increasing the size of the magnetic material, so that a compact and lightweight high-frequency step-up transformer shape for a fluorescent tube can be realized. Furthermore, it is possible to greatly reduce the loss of the magnetic material proportional to the square of the magnetic flux density, which contributes to the improvement of the lighting efficiency of the lighting driving circuit of the fluorescent tube.

Second embodiment.
FIG. 5 is a schematic diagram of the case where the number of outputs is 4 in the fluorescent tube high-frequency step-up transformer 13 according to the second embodiment of the present invention. In the second embodiment, as shown in FIG. 5, a rod-shaped secondary magnetic body 25 is sandwiched between the primary-side magnetic body 23 and the rod-shaped closed magnetic path forming magnetic body 29 to form a closed magnetic flux magnetic circuit. Is done. In the fluorescent tube high-frequency step-up transformer of the second embodiment, the primary coil 21 is wound around the primary side magnetic body 23, and the secondary coil 22 (22 a, 22 b, 22 c, 22 d) is wound around the secondary side magnetic body 25. The closed magnetic path forming magnetic body 29 is joined to the two secondary side magnetic bodies 25 to form a closed magnetic flux magnetic circuit, and the shunt magnetic body 26 is attached so as to cover a part of the secondary coil 22. The diverting magnetic body 26 (26 a, 26 b, 26 c, 26 d) is formed in a U shape, the center portion covers the secondary coil 22, and the end portion is joined to the secondary side magnetic body 25. Generally, the primary coil 21 and the secondary coil 22 are fitted to the primary side magnetic body 23 and the secondary side magnetic body 25 in the state wound around the bobbin, respectively. In FIG. 5, the second embodiment is the same as the first embodiment except that the closed magnetic path forming magnetic body 29 is formed separately from the secondary side magnetic body 25.

  FIG. 6 is a perspective view showing a structure of the fluorescent tube high-frequency step-up transformer 13 according to the second embodiment of the present invention. In FIG. 6, the closed magnetic path forming magnetic body 29 is the same as that of the first embodiment except that it is formed separately from the secondary side magnetic body 25, and thus detailed description thereof is omitted.

Third embodiment.
FIG. 7 is a schematic diagram showing the structure of the fluorescent tube high-frequency step-up transformer 13 according to the third embodiment of the present invention. In the third embodiment, as shown in FIG. 7, a plurality of U-shaped magnetic bodies 27 (27a, 27b, 27c, 27d) are provided between the primary side magnetic body 23 and the closed magnetic path forming magnetic body 29. A closed magnetic flux magnetic circuit is formed across The closed magnetic flux magnetic circuit is formed by a primary magnetic body 23, a plurality of magnetic body portions around which a secondary coil of a U-shaped magnetic body is wound, and a closed magnetic path forming magnetic body 29. In the U-shaped magnetic body, one branch functions as a secondary side magnetic body around which a secondary coil is wound, and the other branch functions as a branching magnetic body. By connecting a plurality of U-shaped magnetic bodies in cascade, the shunting magnetic body can cover a part of the secondary coil 22. In the third embodiment, since the magnetic body around which the secondary coil is wound can be individually manufactured, the U-shaped magnetic body 27 can be flexibly attached according to the number of outputs. In addition, since each U-shaped magnetic body is small in size and inexpensive to manufacture, it is possible to reduce the cost of the high-frequency step-up transformer for a fluorescent tube.

Fourth embodiment.
FIG. 8 is a schematic diagram showing the structure of a fluorescent tube high-frequency step-up transformer 13 according to the fourth embodiment of the present invention. In the fourth embodiment, as shown in FIG. 8, a plurality of E-shaped magnetic bodies 28 (28a, 28b, 28c, 28d) are provided between the primary side magnetic body 23 and the closed magnetic path forming magnetic body 29. A closed magnetic flux magnetic circuit is formed by sandwiching them. The closed magnetic flux magnetic circuit is formed by a primary side magnetic body 23, a plurality of magnetic body portions around which a secondary coil of an E-shaped magnetic body is wound, and a closed magnetic path forming magnetic body 29. The E-shaped magnetic body functions as a secondary side magnetic body on which the secondary coil is wound on the upper and lower branches, and the central branch path functions as a common shunting magnetic body for the two secondary side magnetic bodies at both ends. To do. By connecting a plurality of E-shaped magnetic bodies in cascade, the shunting magnetic body can cover a part of the secondary coil 22. In the fourth embodiment, since the two secondary coils share one magnetic material for shunting, the size and weight can be reduced, and the magnetic material around which the secondary coil is wound can be individually manufactured. Thus, the E-shaped magnetic body 28 can be flexibly attached. In addition, since each E-shaped magnetic body is small in size and inexpensive to manufacture, the cost of the high-frequency step-up transformer for a fluorescent tube can be reduced.

  FIG. 9 is a table comparing the performance of the high-frequency step-up transformer for a multi-output fluorescent tube for a backlight fluorescent tube lighting inverter circuit for a large-screen liquid crystal display panel for each method. As shown in FIG. 9, the high-frequency step-up transformer for fluorescent tubes according to the present invention provides multiple outputs, has good start-up characteristics, is highly efficient, small and lightweight, is reliable, and is inexpensive. It can be seen at a glance that it is superior to other types of high-frequency step-up transformers for fluorescent tubes.

  The present invention can be used as a high-frequency step-up transformer for fluorescent tubes for lighting a plurality of fluorescent tubes arranged in parallel used as a backlight of a liquid crystal display panel.

It is a schematic diagram in the case of the number n of outputs in the high frequency step-up transformer for fluorescent tubes of the first embodiment of the present invention. FIG. 3 is a magnetic circuit diagram of a high-frequency boost transformer for fluorescent tubes having an output number n in the high-frequency boost transformer for fluorescent tubes according to the first embodiment of the present invention. It is a schematic diagram in the case of the number of outputs 4 in the high frequency step-up transformer for fluorescent tubes of the first embodiment of the present invention. It is a perspective view which shows an example of the high frequency pressure | voltage rise transformer for fluorescent tubes of the 1st Embodiment of this invention. It is a schematic diagram in the case of the number of outputs 4 in the high frequency step-up transformer for fluorescent tubes of the 2nd Embodiment of this invention. It is a perspective view which shows an example of the high frequency step-up transformer for fluorescent tubes of the 2nd Embodiment of this invention. It is a schematic diagram in the case of the number of outputs of 4 in the high frequency step-up transformer for fluorescent tubes of the third embodiment of the present invention. It is a schematic diagram in the case of the number of outputs of 8 in the high frequency step-up transformer for fluorescent tubes of the 4th Embodiment of this invention. 5 is a table comparing various performances of a high-frequency step-up transformer for fluorescent tubes for lighting a plurality of fluorescent tubes in parallel according to the present invention. It is a figure which shows an example of the conventional multiple fluorescent tube lighting circuit. It is a figure which shows the voltage-current characteristic of a fluorescent tube. It is a figure which shows an example of the multiple fluorescent tube lighting circuit by a ballast capacitor | condenser system. It is a figure which shows the relationship between the ballast capacitor capacity | capacitance and fluorescent tube current in a ballast capacitor system. It is a figure which shows an example of the multiple fluorescent tube lighting circuit by a leakage magnetic flux inductance system. It is a figure which shows the structure of the high frequency step-up transformer for fluorescent tubes of a magnetic flux parallel coupling type leakage flux inductance system of two outputs. It is a figure which shows the magnetic circuit of the high frequency step-up transformer for fluorescent tubes of the magnetic flux parallel coupling type leakage flux inductance system of n outputs. It is a figure which shows the relationship between the output number n of a high frequency pressure | voltage rise transformer for magnetic flux parallel coupling type | mold leakage magnetic flux inductance type fluorescent tubes, and required input voltage. It is a figure which shows the relationship between the output number n of a high frequency pressure | voltage rise transformer for magnetic-flux parallel-coupling-type leakage flux inductance type fluorescent tubes, and required input current. It is a figure which shows the relationship between the output number n of a high frequency pressure | voltage rise transformer for magnetic flux parallel coupling type | mold leakage magnetic flux inductance type | mold fluorescent tubes, and required primary side magnetic body cross-sectional area. It is a schematic diagram of a high-frequency step-up transformer for a fluorescent tube of a magnetic flux series coupling type leakage flux inductance method. It is a figure which shows the relationship between the output number n and the output voltage of the high frequency step-up transformer for fluorescent tubes of a magnetic flux series coupling type | mold leakage magnetic flux inductance system. It is a figure which shows the conventional high frequency step-up transformer for fluorescent tubes of a leakage magnetic flux inductance system.

Explanation of symbols

13 High frequency step-up transformer for fluorescent tube 21 Primary coil 22, 22a, 22b,... 22n Secondary coil 23 Primary side magnetic body 25, 25a, 25b Secondary side magnetic body 26, 26a, 26b,. 27a to 27d Magnetic material for diversion 28, 28a to 28h Magnetic material for diversion 29 Magnetic material for forming a closed magnetic circuit

Claims (5)

A primary side magnetic body wound with a primary coil, a secondary side magnetic body wound with a plurality of secondary coils and forming a closed magnetic flux magnetic circuit in series with the primary side magnetic body;
Covering a part of the secondary coil, both ends thereof are composed of a magnetic material for shunting formed so as to be joined to the secondary side magnetic material,
The plurality of secondary coils are each connected to a fluorescent tube,
Fluorescent tubes for high frequency step-up transformer, characterized in that diverting the magnetic flux passing through the secondary magnetic member by pre Symbol fraction diverted magnetic material. The secondary side magnetic body is formed in a U-shape, and both ends thereof are formed to be joined to the primary side magnetic body, and a closed magnetic flux magnetic circuit in series by the primary side magnetic body and the secondary side magnetic body. fluorescent tubes for high frequency step-up transformer as claimed in claim 1, characterized that you form. The secondary side magnetic body is composed of two coil secondary side magnetic bodies formed in a bar shape and a closed magnetic path forming magnetic body formed in a bar shape, and one end of each coil secondary side magnetic body 2. The high-frequency tube for a fluorescent tube according to claim 1, wherein the first magnetic member is joined to the primary side magnetic body, and both ends of the magnetic material for forming a closed magnetic path are joined to the other end of the secondary side magnetic body for the coil. Boost transformer. Cross-section is made form with shaped magnetic material co, one of the secondary coils wound toward the magnetic body of the shaped magnetic material of the co and secondary magnetic coil, of the co A magnetic body on which the other secondary coil of the U-shaped magnetic body is not wound is used as a shunt magnetic body, and the primary side magnetic body and the secondary side magnetic body portion for the coil of the U-shaped magnetic body And a closed magnetic path forming magnetic body to form a closed magnetic flux magnetic circuit, and a magnetic flux passing through the coil secondary side magnetic body portion is shunted by the other shunt magnetic body portion of the U-shaped magnetic body. The high frequency step-up transformer for a fluorescent tube according to claim 3. Cross-section is made form a magnetic material E-shaped, said E-shaped magnetic material ga across the secondary-side magnetic coil of the central partial diverted magnetic the ga of the E-shaped magnetic substance A closed magnetic flux magnetic circuit is formed by the primary side magnetic body, the secondary side magnetic body portion of the E-shaped magnetic body, and a closed magnetic path forming magnetic body, and a branch in the center of the E-shaped magnetic body 4. The high-frequency step-up transformer for a fluorescent tube according to claim 3, wherein a magnetic flux passing through the secondary magnetic part for the coil is shunted by the magnetic part for shunting.

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