JPS596489B2 - flyback transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flyback transformer used in a television receiver.

The X-rays generated in the picture tube of a television receiver are
It increases as the high voltage applied to the anode and the beam current flowing through the anode increase. Therefore, X-rays can be suppressed by detecting the voltage and beam current and stopping the operation of the television receiver when the voltage and beam current exceed a certain limit.
Note that the receiver can be stopped by stopping the horizontal oscillation circuit. At that time, the detection of the current is performed in the first
High voltage coil 2 of flyback transformer 1 as shown in the figure
It can be easily detected by inserting the current detection means 3 between one end and the ground, but for voltage detection, the high voltage generated at the output end 4 of the flyback transformer 1 can be directly divided by a resistor and taken out, or the As shown in Figure 1, a method has been proposed in which a detection coil 6 is provided as a tertiary coil on the low-voltage coil 5 side, rectified by a diode 7, and smoothed by a capacitor 8 and a resistor 9. It has the disadvantage of requiring high resistance for pressure and high cost.
In the latter case, the cost is low, but as shown in A in Figure 2, there is a drawback that the voltage ratio to the beam current [ratio of high voltage output (HV) to detection output (DV)] fluctuates greatly. It's not appropriate. However, the latter method had a problem in that changing the primary side resonant capacitance 10 would change the way the voltage changes. For example, when the resonant capacitance 10 is set to the same value, the voltage ratio characteristic changes as shown in FIG. 2 N, which is clearly different from the change in A.

The disadvantage of providing the detection coil 6 on the low voltage side as described above is particularly noticeable in a flyback transformer that performs so-called harmonic tuning. The present invention proposes a flyback transformer devised to eliminate the above-mentioned drawbacks, and details thereof will be explained below with reference to embodiments shown in the drawings.

The low-voltage coil 5 includes a transistor 11 that performs a switching operation according to the horizontal pulse P, and a damper diode 1.
2. There is a primary coil 15 directly connected to the horizontal deflection output section consisting of a horizontal deflection coil 13, a resonant capacitor 10, and a power source 14, and a tertiary coil 16, 6 which is not provided for the original purpose of the flyback transformer. The detection coil 6 is also a low-voltage coil and corresponds to a tertiary coil, but in the following description, it will be referred to as a detection coil for convenience.

In the present invention, as shown in FIG. 3, the detection coil 6 is arranged outside the high-voltage coil 2 to reduce coupling with the low-voltage coil 5 (low-voltage coils other than the detection coil) arranged inside the high-voltage coil 2. Rather, by increasing the influence of the high voltage coil 2, the voltage waveform is brought closer to the waveform on the high voltage coil 2 side.

Therefore, the voltage ratio of the detection coil that approximates this voltage is the second
As shown in Fig. B, there is little variation in the beam current 1, and even if the required resonance quantity 10 becomes, for example, 1, it is stable as shown in Fig. 2.

In addition, in FIG. 3, 17 is a core, 18 is a low voltage coil bobbin, 19 is a high voltage coil bobbin, 20 is a terminal bobbin, 2
1 is an insulating case, 22 is a high voltage lead wire, and 24 is a rectifier diode.

Reference numeral 25 denotes a bobbin for the detection winding, which has a hole 26 into which the terminal pin 20 fits, and is fixedly held by the terminal holder 27.

FIG. 4 and subsequent figures show other specific examples of the present invention, in which 28 is a split-type low-voltage coil bobbin integrally molded with a terminal holder 31 having a terminal holder 30 in which a terminal pin 29 is implanted; The inside thereof is hollow so that a core 32 (see FIG. 8) can be inserted therethrough.

33 is a high-voltage coil bobbin in which the high-voltage coil 2 is wound in sections in grooves formed by a plurality of flanges 34, and the inside thereof is hollow, into which the low-voltage coil bobbin 28 is inserted.

23 and 24 are rectifier diodes, and 35 is a collar 3 at the end.
This is a connection terminal provided at 4a.

36 is a detection coil bobbin around which the detection coil 6 is wound, and its inner diameter is larger than that of the high voltage coil bobbin 33 so that it can be placed outside of the high voltage coil bobbin 33.

As clearly shown in FIG. 5, the detection coil bobbin 36 has a protrusion 38 at one end of a short cylindrical portion 37, and a fixing protrusion 39 for fixing at the other end. 39
As shown in FIG. 6, a semicircular recess 40 into which the terminal holder 30 of the terminal holder 31 can fit is formed inside the terminal holder 31 . Therefore, the detection coil bobbin 36 is fixedly held on the terminal holder 31. The fixing protrusion 39 and the protrusion 38 also serve as a position regulator for the detection coil 6 wound around the cylindrical portion 37. Each coil 5 shown in FIG.
The bobbins 2 and 6 are assembled with their respective bobbins 28, 33, and 36, housed in an insulating case 41 as shown in FIG. 7, and molded with an insulating resin 42. At this time, it goes without saying that care must be taken to connect the lead wires of the detection coil 6 to appropriate terminal pins 29 of the terminal holder 31 so as to enable connection to an external circuit. In FIG. 7, 43 is an insulating resin that hardens at room temperature, and is applied after the other insulating resin 42 is hardened.

The resin 42 is injected in a liquid form while the insulating case 41 is turned upside down from that shown in FIG. 7, and a heat-resistant rubber bushing of the same shape is interposed in the area where the room-temperature curing resin 43 is to be applied. It is cured by applying heat. The constantly hardening resin 43 is applied in liquid form with the rubber bushing removed and the high voltage lead wire 44 fitted to the terminal 35, and cured by being left for a while. In this way, the insulating case 41 equipped with the coils 2, 5, and 6 is mounted on a monopod of a magnetic core assembled in a mouth shape by a pair of U-shaped cores 32, 32 [see Fig. 8]. Completed as a back transformer. The voltage picked up by the detection coil 6 is rectified by a diode 7 (see Figure 1) connected to a terminal pin 29, smoothed by a smoothing circuit consisting of a capacitor 8 and a resistor 9, and then detected as one input. The beam current (current detected by the detection means 3 in FIG. 1) is applied as another input to the AND circuit, and functions to control the operation/non-operation of the horizontal oscillation circuit through this AND circuit. It goes without saying that when carrying out the present invention, it is not necessary to limit it to the illustrated embodiment, and that various modifications can be made. As explained above, according to the present invention, the change in the detection output due to the change in beam current and the decrease in the primary side resonant capacitance 10 suitably follows the high voltage output (H) of the flyback transformer, and has the effect that there is little variation. Therefore, this detection voltage is
This is convenient when used to prevent line generation.

In addition, a coil bobbin is provided to place a part of the detection coil outside the high-voltage coil, and this bobbin is fixedly held on the terminal holder, so the structure is simple and the terminal is held when connecting to the outside. Another advantage is that the terminal pins on the body can be used. Incidentally, a secondary effect of the present invention is that the linking of the flyback transformer (this ringing consists of external leakage components) is absorbed by the low voltage coil placed outside the high voltage coil, so that the high voltage output (HV
), and at the same time, the effect of ringing leaking from the flyback transformer on other circuits placed near the flyback transformer, such as the grounding foil of a printed wiring board, can be suppressed. There is also.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a flyback transformer having a voltage detection coil, and FIG. 2 is a characteristic diagram for explaining the conventional drawbacks and the effects of the present invention. FIG. 3 is a sectional view showing a part of a flyback transformer embodying the present invention. Figure 4 and the following diagrams relate to other embodiments of the present invention, in which Figure 4 is an exploded view of the main components, Figure 5 is a perspective view of a portion thereof, Figure 6 is an explanatory diagram of a portion thereof, and Figure 7 The figure is a partially sectional view showing the assembled state, and FIG. 8 is a drawing showing the state after completion. 2...
...High voltage coil, 5...Low voltage coil, 6...
...Detection coil (part of low voltage coil), 19, 33.
...High voltage coil bobbin, 18,28...
Low voltage coil bobbin, 25, 36...detection coil bobbin, 27, 31...terminal holder.

Claims (1)

[Scope of Claims] 1. In a flyback transformer in which a low-voltage coil is arranged inside a high-voltage coil, a coil bobbin that is directly integrated and fixed to a terminal holder is provided outside the high-voltage coil, and the magnitude of the output voltage of the high-voltage coil is determined. A flyback transformer characterized in that a detection coil is wound around the coil bobbin for extracting a small voltage representing . 2. Claim 1, characterized in that the terminal holder is integrally molded with a bobbin of a low-voltage coil arranged inside a high-voltage coil bobbin wound with a high-voltage coil.
Flyback transformer as described in section. 3. The coil bobbin arranged outside the high voltage coil has a cylindrical part for winding a part of the low voltage coil, a protrusion provided at one end of the cylindrical part, and a fixed protrusion provided at the other end. 2. The flyback transformer according to claim 1, wherein the fixing protrusion has a recess that fits into the terminal holding portion of the terminal holding body. 4. Claim 1, wherein the coil bobbin disposed outside the high-voltage coil is disposed on a portion of the high-voltage coil where the induced voltage is low among the high-voltage coils that are divided and wound around the split-type high-voltage coil bobbin. Flyback transformer as described in section.