JPS61247007A - Transformer for tv receiver - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a transformer for a television receiver having a core in which the windings of an isolation transformer and the windings of a horizontal output transformer of a power supply circuit section are arranged. .

Prior art television receivers generally include a horizontal output stage with a so-called high-voltage transformer, the core of the transformer having inter alia a primary winding, a high-voltage winding and, if appropriate, a A further additional winding is provided for taking out the pulse. High energy transmitted for horizontal deflection and approximately 25 kV
Due to the magnitude of the high voltage generated, ranging from 30kV to 30kV,
The core of this type of horizontal output transformer is a relatively expensive and heavy component.

On the other hand, today television receivers are increasingly equipped with so-called power supply circuits (5ch8, tne-tztei
l) is now used. The power circuit section is
It includes a so-called isolation transformer. The isolation transformer acts to galvanically isolate the receiver circuit from the power supply and
Voltages of different magnitude and different polarity are tapped off from the secondary winding via a rectifier circuit. This isolation transformer also requires one core.

It is known to arrange the windings of the power circuit section and the horizontal output transformer on a common core so that only 11 cores are required in total for the power circuit section and the horizontal output transformer. There is (Funkscha v'rfy (Funkscha)
u) 1976, Volume 9, pp. 359-363
page). This reduces the total core volume and weight required.

Problem to be Solved by the Invention The power supply circuit supplies inter alia the audio output stage of a television receiver. The load due to the output stage varies over a wide range by a value of approximately 70W. This load variation can affect the horizontal deflection circuit and high voltage output due to the magnetic coupling of the windings of both the power circuit section and the horizontal output transformer.

Furthermore, the load on the horizontal output transformer is likewise not constant, but varies by a value on the order of 30 W, depending on the brightness of the respective image. This load fluctuation may affect audio playback.

It is an object of the invention to improve the decoupling between the two windings and to reduce the effects in the opposite direction in a transformer of the type mentioned at the outset for the power supply circuit and the horizontal output transformer.

Means for Solving %Q This problem is solved by the structure set forth in claim 1 of the present invention. Advantageous embodiments of the invention are described in the embodiment section of the patent claims.

OPERATIONS AND EFFECTS OF THE INVENTION Due to the inventive configuration of the transformer, most of the magnetic flux generated from the power circuit section and the horizontal output transformer is isolated from each other. This is because the magnetic flux of each winding flows only or mostly through the inner leg, and because of the high reluctance another winding was actually arranged. It doesn't flow through the outer legs, so it's okay. A change in the load on one of both windings therefore does not actually affect the functioning of the other winding. By combining the power supply circuitry and horizontal output transformer windings into one core, ferrite material for the core, assembly time, and inspection time are reduced. Advantageously, both windings are polarized in such a way that the magnetic fluxes in the inner legs run in opposite directions and cancel each other at least temporally and partially. Then take a cross section of the inner leg,
It can be reduced accordingly to the magnetic flux acting there. This is especially true when the power supply circuitry and the horizontal output transformer are synchronized, ie both operate with a horizontal scanning frequency of approximately 16 kHz.

The cross-sections of the individual legs can advantageously be selected in accordance with the magnetic flux actually occurring in them. For that purpose, 2
The two outer legs can have different cross-sections. A zero air gap value in the inner legs is not practically achievable, since the core surfaces are fixedly joined. This is because the unavoidable roughness in any case always creates a magnetic air gap.However, this air gap is on the order of 2-4μ, whereas an air gap intentionally provided on the outer leg is of the order of 1 mm, which means that the magnetic flux flowing in each case via the other outer leg is only 1% of the magnetic flux flowing through the inner leg, which is disadvantageous for the reluctance and therefore for the flux distribution; This means that it can be ignored. When the power supply circuitry and the horizontal output transformer do not operate on the same frequency, i.e. when they operate asynchronously, it is advantageous to shield both windings from each other. The associated circuits for the transformer and the horizontal deflection circuit as well as the power supply circuit are shown subsequently in the description of the exemplary embodiments.

Embodiments Next, the present invention will be explained in detail with reference to the drawings, with reference to the illustrated embodiments.

FIG. 1 shows the configuration of the core of the invention with the power supply circuitry and the windings for the horizontal output transformer, also referred to as a flybag transformer. In FIG. 1, two E-shaped core halves 1.2 are combined into a so-called E-core with two outer legs 3, 4 and one inner leg 5. In FIG. The outer legs 3, 4 are provided with an air gap 6.7 having a length of approximately 1 mm, and the legs δ on one side are substantially connected to each other by the fixed connection of the two halves 1, 2. does not have.

If a magnetic air gap still remains there, it is caused by the roughness of the bonding surface.
It is on the order of 6μ to 6μ. The outer leg 3 carries the winding 8 for the power supply circuit (SMPS), while the outer leg supports the winding 9 for the horizontal power transformer (PPHV). In reality, the windings 8, 9 consist of several partial windings that are separated from each other. The winding 8 is
For example, it consists of a primary winding, a so-called feedback coupling winding, a control winding and a series of secondary windings for generating different operating voltages. The winding 9 consists, for example, of a primary winding of a horizontal output transformer, a high-voltage winding and a further additional winding for leading off the horizontal scanning flyback coil.

The magnetic flux φ1 generated in the outer regeneration actually flows only through the inner leg 5. This is because the regenerative magnetic resistance on the outside is approximately 100 times larger than the magnetic resistance on the inner leg 5. Magnetic flux φ2 generated in the outer leg 3
likewise flows only through the inner leg 5. This is because the magnetic resistance of the outer leg 3 is 1 greater than the magnetic resistance of the inner leg 5.
There is 1 because it is 00 times larger. The windings 8 and 9 have magnetic flux φ1. φ
2 are wound on the inner leg 5 with polarities set such that they cancel each other out.

The compensation of the magnetic flux in the inner leg 5 is actually a synchronous actuation,
It is therefore possible at the same operating frequency of the power circuit section and the horizontal output transformer, ie the horizontal scanning frequency.

However, since the currents flowing through the windings, and therefore the magnetic fluxes, do not necessarily have the same duration and amplitude, complete compensation is usually not possible. This compensation is then implemented in such a way that it acts on a portion of the amplitude, at least over the majority of the time.

The cross sections of the outer legs 3, 4 are similar to those of the windings 8, 9.
are shown differently to show that they have been chosen to match the actual magnetic flux generated by. The cross section of the inner leg 5 is also aligned with the magnetic flux acting thereon,
As a result, it is possible to save ferrite material for the inner leg 5, especially in synchronous operation.

FIG. 2 shows another embodiment in which the core configuration of FIG. 1 is modified. Here, the two windows formed by the core are chosen to have different sizes. The left-hand window has a height Hl and a width B1, and the right-hand window has a height H2 and a width B2, with H1f=H2 and B1≠B2. This results in an alignment of the core geometry to the actual value of the magnetic flux and the coil geometry. The height H2 of the right window is selected to be relatively small 1, and the height of the overall core is also selected to be relatively small due to the removal or notch. By configuring the core in this manner, the cost and weight of the core material, ie ferrite, can be significantly reduced.

The circuit of FIG. 3 will now be described in relation to the curve diagram of FIG. The curve diagram illustrates the important voltages and currents in the time course of the period in a rising transient state. In this case, Φ time intervals arise.

tl-t2: The electronic switch in the form of transistor 11 is switched off by the control voltage of FIG. 4a applied to its base. The collector voltage shown in FIG. 4C is generated, and the collector current 12 is zero as shown in FIG.
The energy stored in the primary winding 13 causes a current i4 to flow through the flyback diode 14 (Fig. Φd), so that the energy stored in the primary winding 13 The capacitor 16, which is connected in series with the The course of i4 is flat as long as the current 17 flows.

At time t2, the magnetizing current i3 flowing from the winding 13 passes through the zero point (FIG. f).

t2-t3: With the control voltage U1 of FIG. 4a, the transistor 11 becomes conductive and a current 19 flows which recharges the storage inductance 19 (FIG. 4g). The current 17 is zero, so that the current i rises relatively steeply through the diode 14 (FIG. d). The magnetizing current i3 has a flat course in the positive direction (FIG. 4f).

The state does not change during the t3-t4 nitrans. This is because the time changes of current and magnetic flux maintain the same direction.

Collector current 1 of transistor 11, illustrated in FIG.
2 increases by the positive component of the deflection current iA shown in the fourth diagram, which passes through the zero point at time t3. diode 1
The current i4 flowing through I becomes zero at time t3 (Fig. d).

t4-t1: At time t4, transistor 11 is cut off. The magnetic energy stored in the deflection coil 12 and the primary winding 13 causes a second current 110 to flow through the flyback capacitor 20 and causes it to move in the positive direction until all the energy is stored in the capacitor 20 at time t5. Charge (Figure I). Subsequently, the energy is t5
At ~t1, the deflection coil 12 and the primary winding 13 are turned on again.
will be sent to. In the time interval t4-t1, the current 17
flows through the diode 18 to the primary winding 13, thereby compensating for energy loss. The current 17 is
Distributed to charge capacitors 15, 16 and 20. During the flyback period and largely in the flyback capacitor 20, energy loss compensation takes place, so that no interfering voltage peaks occur that would have to be attenuated. The circuit of FIG. 3 is particularly advantageous in terms of cost. This is because only one electronic switch in the form of transistor 11 is required for the deflection circuit and the power circuit section. For example, the transformer of the present invention having the circuit shown in FIG. 3 is also suitable for equipment having relatively large power consumption of 50 to 150 W. Compared to known devices, various damping elements are omitted. Further efficiency improvements are realized. This is because power losses caused by attenuation are avoided or reduced! be. The power for attenuation, which has been wasted up to now, is returned to the deflection system and effectively utilized in the configuration of the present invention.

In FIG. 5, the structure of the transformer is illustrated with the effective magnetic flux φ. The transformer shown has two outer legs and 3, each with an air gap 6.7, in which the windings 19 and 17 of the power circuit are arranged for regeneration, and in leg 3. Windings 23 to 1 for the audio output stage
A secondary winding 13, a secondary winding 24 for generating various operating voltages, a winding 25 for generating high voltage, and a winding 26 for controlling the dry circuit are arranged. There is. The transformer has a middle leg 5 with no gap. During the time interval t1-t2, the magnetic flux of leg 3 mostly closes through the middle leg 5 without an air gap 1,
The deflection circuit is significantly decoupled to the power supply circuitry.

In the time interval t2-t3, the magnetic flux via regeneration is also
The magnetic flux through the legs 3 is also approximately equal in phase and amplitude. They are thus closed via regeneration and 3, resulting in a fixed coupling, with only differences in amplitude depending on the supply voltage and the load being closed via the middle leg 5. The energy loss compensation carried out in the time interval t4-t1 is carried out by the fixed connection between legs 4 and 3. Since excess energy is closed off and not transmitted via the middle leg 5, no undesirable voltage peaks occur.

[Brief explanation of the drawing]

1 is a diagram illustrating the configuration of a core of the invention with a winding for a power supply circuit and a horizontal output transformer, and FIG. 2 is a schematic diagram illustrating another embodiment of the core of FIG. Yes, 3rd
There is a diagram showing an embodiment of the circuit for the core of FIG. 1, FIG. 4 is a diagram showing the course of voltage and current to explain the operation of the circuit of FIG. The figure shows the third
1 is a cross-sectional view of a transformer with a core and individual windings used in the illustrated circuit; FIG. 1.2... Core half, 3, 4... Outer leg, 5...
・Inner leg, 6,7. )il, Bl, H2,82...
Air gap, 8... Winding for power circuit section, 9... Winding for output transformer, 11... Transistor switch, 1
3.19...Primary winding, 17.24...Secondary winding,
18...Diode, 25...High voltage winding l
Fig, 2 WaFig, 5

Claims (1)

[Claims] 1. In a transformer for a television receiver having a core in which a winding of an isolation transformer and a winding of a horizontal output transformer of a power supply circuit section are arranged, the cores (1, 2) are: two outer legs (3, 7) each with an air gap (6, 7);
4) and one inner leg (5) having substantially no air gap;
A transformer for a television receiver, characterized in that the two windings (8, 9) are arranged on the outer legs (3, 4). 2. The television receiver according to claim 1, wherein the windings (8, 9) are wound so that their magnetic fluxes (φ1, φ2) pass in opposite directions in the inner legs (5). machine transformer. 3. The television receiver according to claim 1, wherein the cross section of the outer legs (3, 4) is selected to match the magnetic flux (φ1, φ2) generated in the cross section. Trance. 4. The transformer for a television receiver according to claim 1, wherein the cross section of the inner leg (5) is smaller than the cross section of the outer legs (3, 4). 5. Air gaps (6, 7) in the outer legs (3, 4)
2. A transformer for a television receiver as claimed in claim 1, wherein the length of the transformer is on the order of 1 mm. 6. Air gaps (6, 7) on outer legs (3, 4)
) to the length of the air gap in the inner leg (5) is of the order of 100. 7. A transformer for a television receiver according to claim 1, wherein the two windings (8, 9) are mutually shielded. 8. The two core windows formed by the legs have different heights (H1, H2) and/or different widths (
B1, B2) A transformer for a television receiver according to claim 1. 9. The total height of the cores (1, 2) is a relatively small height (H2
9. A transformer for a television receiver according to claim 8, wherein the height of the core (1, 2) is selected to be lower than the height of the core (1, 2) in the remaining area by the removal or cutout in the area of the window. 10. The first outer leg (3) is provided with a first primary winding (13) for the horizontal deflection circuit, and the second outer leg (4) is provided with a first primary winding (13) for the power supply circuit. 2 primary winding (
19) and is coupled to the other primary winding (19), the secondary winding being coupled to the other primary winding (19) via a diode (18). A transformer for a television receiver according to claim 1, which is connected to the first primary winding (13) (FIGS. 3 and 5). 11, the first outer leg (3) has a first primary winding (1
3) A television receiver according to claim 10, in which a secondary winding (24) for generating an operating voltage and a high voltage winding (25) are additionally arranged (Fig. 5). trance. 12, the second outer leg (4) has a second secondary winding (19
) and a secondary winding (17) coupled to the winding (Fig. 5). 13. The second outer leg (4) first has a first part of the first primary winding (19), above it the secondary winding (17) and further above it the second primary winding (19). 13. A transformer for a television receiver according to claim 12, in which a second part of the winding (19) is arranged (FIG. 5). 14. In addition to the second outer leg (4), a winding (23) for generating the operating voltage (U6) for the audio output stage
(FIG. 5) A transformer for a television receiver according to claim 10. 15. On the first outer leg (3) there is additionally arranged a winding (26) for controlling the driver circuit for the common electronic switch (11) of the horizontal deflection circuit and the power supply circuit ( FIG. 5) A transformer for a television receiver according to claim 10.