BLAUPUNKT MS 63-76 B Chassis FM100-30 DTS Internal Chassis and CRT VIEWING.

BLAUPUNKT MS 63-76 B Chassis FM100-30 DTS
Mixed technology with ICs and HYBRAM ICs ASICs

On a ceramic substrate, spiral-type inductors of a single layer wiring of a metal thin film are provided and respectively connected to a wiring pattern formed on another face of the substrate via through holes. A semiconductor chip is flip-chip mounted on the substrate in a face-down manner. On the face of the semiconductor chip, capacitors composed of a highly dielectric material, resistors formed by an ion implantation method or a thin-film forming method, and FETs are provided, respectively. Interconnection between the substrate and an external circuit board is achieved employing terminals formed at end faces of the substrate. The terminals have a concave shape with respect to the end face of the substrate. Thus, there is no need to use a package, and miniaturization and reduction in cost of a high-performance hybrid IC is achieved.




BLAUPUNKT MS 63-76 B Chassis FM100-30 DTS Description of the EHT FLYBACK Transformer used in Blaupunkt CHASSIS types.

High-voltage-secondary transformer, particularly television line transformer:




To decrease the internal resistance of a transformer operable as a television line transformer of the "diode-split" type, the secondary winding sections are matched to each other and to the frequency of operation of the transformer in such a manner that the current in the respective sections will flow at respectively different instants of time; in a preferred form, the winding sections, on the average, are tuned to a harmonic of the frequency of the signal applied to the primary and are positioned on winding forms or holders such that the distance between the bottom wall of the primary and the bottom wall of the secondary is constant over the entire length of the windings. Preferably, the tuning of the respective winding sections is effected by matching of the primary winding to the secondary within the region of the secondary winding sections.




1. High-voltage secondary transformer, particularly television line transformer, having

a primary winding (5) and a secondary winding (7a, 7b, 7c) in which the secondary winding is subdivided into a plurality of windings sections (7a-7b-7c), and a plurality of rectifier diodes (10) connecting said secondary winding sections together,

wherein, in accordance with the invention,

the secondary winding sections (7a, 7b, 7c) are physically positioned with respect to the primary winding to form spatially separated winding sections, each having individual inductance and capacity values and with respect to the primary, and each other, said positioning on the primary winding being effected to result in current flow in the respective sections (7a, 7b, 7c) of the secondary at respectively different instants of time.

2. Transformer according to claim 1, wherein the secondary winding sections are tuned to a harmonic of the frequency of the signal applied to the primary winding (5).

3. Transformer according to claim 2, wherein the respective winding sections (7a, 7b, 7c) of the secondary are tuned to the primary (5) by matching the primary winding to the secondary in the region of the respective secondary winding section.

4. Transformer according to claim 3, wherein the distance between the inner dimension of the primary winding and the inner dimension of the secondary winding is constant throughout the length of a winding section.

5. Transformer according to claim 4, wherein said distance is constant throughout the length of all the winding sections.

6. Transformer according to claim 5, for use as a television high-voltage transformer further comprising a resistor (R) connected to one of the secondary winding sections to provide a bleeder voltage for focussing of an image tube of a television apparatus,

comprising a housing being formed with a first portion receiving said primary winding (5) and said secondary winding sections (7a, 7b, 7c) and a resistor chamber portion defining a chamber (16) in which said resistor (R) is located, said resistor chamber portion being separated from the portion retaining said windings by an air gap (15).

7. Transformer according to claim 3, for use as a television high-voltage transformer further comprising a resistor (R) connected to one of the secondary winding sections to provide a bleeder voltage for focussing of an image tube of a television apparatus,

comprising a housing being formed with a first portion receiving said primary winding (5) and said secondary winding sections (7a, 7b, 7c) and a resistor chamber portion defining a chamber (16) in which said resistor (R) is located, said resistor chamber portion being separated from the portion retaining said windings by an air gap (15).

Description:

The present invention relates to a transformer providing a high-voltage secondary output, and particularly to a television line transformer having a secondary winding which is subdivided into winding sections or portions interconnected by rectifiers.

BACKGROUND AND PRIOR ART

Television line transformers frequently have divided secondaries, that is, secondaries which are subdivided into sections, connected by rectifier diodes. These transformers, particularly when used as line transformers in TV apparatus, are supplied at the primary with signals of line frequency, and then provide the anode voltage for the TV electron gun, image tube at the secondary. Line transformers in which the secondaries are subdivided and connected by diodes are referred to as "diode-split" transformers. The voltages induced in the partial secondary windings or winding sections add in the form of a voltage doubler or voltage multiplier until the desired high voltage is reached. The stray or leakage capacitances within the transformer and particularly the stray capacitances of the partial windings with respect to a reference voltage act as intermediate storage capacities for the portions of the voltages which are being added.

Transformers of this type have a disadvantage in that they have poor regulation. As a voltage source, they have a comparatively high inherent or internal resistance. Changes in loading which may occur thus lead to changes in output voltage. Applied to a TV system, instability of the format of the resulting image may occur. Changes in loading often are the consequence of changes in beam current.

THE INVENTION

It is an object to provide a transformer, particularly suitable as a line transformer, which has a suitable low internal resistance so that the output power obtained therefrom will be at a voltage which is essentially constant and independent of variations in loading experienced in ordinary television sets, without the necessity of complex circuitry.

Briefly, a transformer of the diode-split type is so constructed that the secondary winding sections are matched to each other and to the frequency of operation of the transformer that the current in the respective section flows at respectively differently instants of time. In a preferred form, the winding sections, on the average, are tuned to a harmonic of the frequency of the signals applied to the primary. Tuning of the various winding sections can be effected by matching the configuration or winding arrangement or number of turns of the respective sections to the primary within the range of the inductive coupling between the primary and the particular section of the secondary. In accordance with a preferred feature, the primary is located within the secondary, and the distance between the inner winding portion of the coil of the primary and the inner winding portion of the coil forming the secondary is essentially constant over the entire width of the windings.

Transformers of this type often are associated with external circuitry, and particularly with a resistor which is connected to a specific secondary section and on which the focussing voltage for the TV image tube can be taken off. In accordance with a feature of the invention, the housing for the transformer is formed with a lateral chamber, remote from the transformer windings themselves and separated therefrom by an air gap. The transformer windings, as well as the chamber for a resistor from which the tapping voltage can be taken off, is filled with a potting compound. This resistor, also referred to as a bleeder resistor, can be applied by thin film or hybrid technology on a small ceramic plate and, by the specific location, is removed from the field generated by the transformer and thus provides a stable output voltage.

The transformer construction in accordance with the present invention, when used as a line transformer in a TV set provides for a more stable picture since it has substantially improved regulation with respect to prior art transformers by having an inherent or inner resistance which is less than that of previously used units. Tuning of the sections of the secondary winding is simple by matching the configuration of the primary winding to the configuration of the secondary sections, which is easier to accomplish in manufacture than if the secondary is matched to the primary.

Drawings, illustrating an example, wherein:

FIG. 1 is a side view, partially in section, of a line transformer for television use, having rectifier diodes located within the transformer and connected between individual winding sections; and

FIG. 2 is a top view, with part of the housing cut away and in section, of the transformer of FIG. 1.

The transformer is a "diode-split" transformer, the principle of which is known. The transformer 1 is located within a plastic, typically injection-molded plastic, housing 2 which receives a potting compound 3 after the transformer is assembled within the housing. In FIG. 1, the front wall of the housing has been removed. The housing 2 receives, or inherently forms, a coil form 4 for the primary winding 5 of the transformer. The coil form 4 may be part of the housing structure, that is, molded integrally therewith, the coil 5 being wound initially as a coreless or formless structure so that it can be slipped directly over the form 4 which, as best seen from FIG. 2, is essentially a cylinder open at one end. A different type of housing can be used, however, in which the coil form 4 does not form an intergral, molded part, but rather is inserted as a separate form or winding body for the primary.

A coil carrier 6 is located on the primary 5 to receive the secondary of the transformer 1. In accordance with a feature of the invention, the secondary winding is wound in three sections 7a, 7b, 7c, which subdivide the secondary. The secondary winding sections 7a, 7b, 7c are each located in three winding chambers 6a, 6b, 6c of the form 6. The winding chambers 6a, 6b, 6c each have five winding grooves 8 in which the winding sections 7a, 7b, 7c each are uniformly distributed. These winding grooves 8 may, however, be non-uniformly distributed if it is desired to effect matching of the tuning of the winding sections to the primary by this distribution; in a preferred form, however, the distribution of the grooves 8 is uniform. The result of this subdivision of the windings into sections 7a, 7b, 7c, physically separated, i.e. axially spaced from each other (see FIG. 1), is a consequent division of capacity and inductance of the secondary into respectively, individually positioned individual capacity and inductance values and mutual capacity and inductance values of the sections, resulting in different phasing of the current flow, i.e. current flow in the respective sections at respectively different instants of time.

Holders 9 are located above each one of the winding chambers 6a, 6b, 6c, as best seen in FIG. 2, preferably formed integrally with the winding holder or body 6. The holders 9 receive the diodes 10. The diodes 10 are located in the holders 9 with externally bent connecting wires 11. The connecting wires extend through openings or passages of caps 12 snapped over the holders 9, thus securing the diodes 10 on the holders 9. The low-voltage connection of the transformer 1 is effected by connecting pins 13; some of the pins 13, shown in FIG. 1, may be left unconnected and serve as positioning elements. The high-voltage load is connected by a high-voltage cable--not shown--to a connecting bushing 14 located at the side opposite the low-voltage terminals 13.

The housing is formed with a separately arranged chamber 16, separated from the remainder of the transformer by an air gap 15. A ceramic plate 17 on which a resistor R, applied by hybrid technology is located, is positioned in the chamber 16. Thus resistor, forming a bleeder resistor, can be used to generate the focussing voltage for the image tube of the TV set for which the transformer is particularly suitable by connection to a tap point on one of the winding sections 7a, 7b, 7c, by a suitable connection, not shown for simplicity.

The average tuning frequency of the winding sections 7a, 7b, 7c is tuned to a harmonic of the frequency of the signal applied to the primary. The respective winding sections 7a, 7b, 7c are tuned by matching the primary winding to the secondary in the region of inductive coupling of the primary to the respective section of the secondary. The inner diameter of the form 4 for the primary winding and the inner diameter of the secondary winding form or holder 6 are concentric and equidistant throughout at least the length of one of the winding sections, and preferably uniform throughout their entire length.

The transformer will form a voltage source of low internal resistance and thus can be used without additional circuitry or without increasing the size of the transformer. Miniaturization of the transformer is thus possible which is particularly important in modern television equipment.

Making the inner wall of the primary winding and the inner wall of the secondary winding in such a manner that the distances between these two walls are uniform reduces the overall size and substantially simplifies manufacture of the tuned winding sections. It was previously thought necessary to tune the winding sections with respect to each other by varying the thickness of the windings or the distances of the inner limits of the windings with respect to each other. In the transformer as described, this is not necessary and, rather, the inner wall of the transformer primary and the inner wall of the transformer secondary winding sections is uniform which results in a structure in which the comparatively complex secondary winding sections can be made identical to each other, since tuning or matching of the output is obtained by matching the secondary and primary by the shape of the primary winding. The primary winding is matched to the secondary by different magnetic coupling of the primary with respect to the sections of the secondary, that is, with a coupling which differs between the sections of the secondary; and by respectively different stray capacitances between the sections of the secondary and the primary winding, that is, by so arranging the coils that the stray capacitances of any one of the sections 7a, 7b, 7c of the secondary with respect to the primary are different.

The potting compound 3 can be filled into the transformer after assembly; the resistor secured to the ceramic plate 17 is connected before potting to a tap of the secondary winding. The resistor, by being located in chamber 16 separated from the housing of the transformer itself, eliminates undesired capacitative losses or stray currents which otherwise occur between the secondary winding of the transformer and the resistor. Such stray currents are a minimum by the separation of the resistor from the remainder of the transformer by the air gap, and its positioning in a separate chamber. This separation effectively eliminates electric stray fields which have a disturbing effect at line frequency, since the focussing voltage is undesirably modulated thereby.

In an operating example, a transformer designed for 625 lines, 50 frames (PAL standard) was wound with a diameter of the bottom 4 of 22.5 mm, having 110 turns of 0.31 mm wire to form the primary; over this form, a secondary with an inner winding diameter for the winding sections 7a, 7b, 7c, of 24.1 mm was placed; the secondary was composed of 2910 turns of 0.071 mm wire, having each three sections of 5 grooves, interconnected by diodes.

Switch Mode Power supply is based on TDA4601d (SIEMENS)

TDA4601 Operation. * The TDA4601 device is a single in line, 9 pin chip. Its predecessor was the TDA4600 device, the TDA4601 however has improved switching, better protection and cooler running. The (SIEMENS) TDA4601 power supply is a fairly standard parallel chopper switch mode type, which operates on the same basic principle as a line output stage. It is turned on and off by a square wave drive pulse, when switched on energy is stored in the chopper transformer primary winding in the form of a magnetic flux; when the chopper is turned off the magnetic flux collapses, causing a large back emf to be produced. At the secondary side of the chopper transformer this is rectified and smoothed for H.T. supply purposes. The advantage of this type of supply is that the high chopping frequency (20 to 70 KHz according to load) allows the use of relatively small H.T. smoothing capacitors making smoothing easier. Also should the chopper device go short circuit there is no H.T. output. In order to start up the TDA4601 I.C. an initial supply of 9v is required at pin 9, this voltage is sourced via R818 and D805 from the AC side of the bridge rectifier D801, also pin 5 requires a +Ve bias for the internal logic block. (On some sets pin 5 is used for standby switching). Once the power supply is up and running, the voltage on pin 9 is increased to 16v and maintained at this level by D807 and C820 acting as a half wave rectifier and smoothing circuit. PIN DESCRIPTIONS Pin 1 This is a 4v reference produced within the I.C. Pin 2 This pin detects the exact point at which energy stored in the chopper transformer collapses to zero via R824 and R825, and allows Q1 to deliver drive volts to the chopper transistor. It also opens the switch at pin 4 allowing the external capacitor C813 to charge from its external feed resistor R810. Pin 3 H.T. control/feedback via photo coupler D830. The voltage at this pin controls the on time of the chopper transistor and hence the output voltage. Normally it runs at Approximately 2v and regulates H.T. by sensing a proportion of the +4v reference at pin 1, offset by conduction of the photo coupler D830 which acts like a variable resistor. An increase in the conduction of transistor D830 and therefor a reduction of its resistance will cause a corresponding reduction of the positive voltage at Pin 3. A decrease in this voltage will result in a shorter on time for the chopper transistor and therefor a lowering of the output voltage and vice versa, oscillation frequency also varies according to load, the higher the load the lower the frequency etc. should the voltage at pin 3 exceed 2.3v an internal flip flop is triggered causing the chopper drive mark space ratio to extend to 244 (off time) to 1 (on time), the chip is now in over volts trip condition. Pin 4 At this pin a sawtooth waveform is generated which simulates chopper current, it is produced by a time constant network R810 and C813. C813 charges when the chopper is on and is discharged when the chopper is off, by an internal switch strapping pin 4 to the internal +2v reference, see Fig 2. The amplitude of the ramp is proportional to chopper drive. In an overload condition it reaches 4v amplitude at which point chopper drive is reduced to a mark-space ratio of 13 to 1, the chip is then in over current trip. The I.C. can easily withstand a short circuit on the H.T. rail and in such a case the power supply simply squegs quietly. Pin 4 is protected by internal protection components which limit the maximum voltage at this pin to 6.5v. Should a fault occur in either of the time constant components, then the chopper transistor will probably be destroyed. Pin 5 This pin can be used for remote control on/off switching of the power supply, it is normally held at about +7v and will cause the chip to enter standby mode if it falls below 2v. Pin 6 Ground. Pin 7 Chopper switch off pin. This pin clamps the chopper drive voltage to 1.6v in order to switch off the chopper. Pin 8 Chopper base current output drive pin. Pin 9 L.T. pin, approximately 9v under start-up conditions and 16v during normal running, Current consumption of the I.C. is typically 135mA. The voltage at this pin must reach 6.7v in order for the chip to start-up.


Semiconductor circuit for supplying power to electrical equipment, comprising a transformer having a primary winding connected, via a parallel connection of a collector-emitter path of a transistor with a first capacitor, to both outputs of a rectifier circuit supplied, in turn, by a line a-c voltage; said transistor having a base controlled via a second capacitor by an output of a control circuit acted upon, in turn by the rectified a-c line voltage as actual value and by a reference voltage; said transformer having a first secondary winding to which the electrical equipment to be supplied is connected; said transformer having a second secondary winding with one terminal thereof connected to the emitter of said transistor and the other terminal thereof connected to an anode of a first diode leading to said control circuit; said transformer having a third secondary winding with one terminal thereof connected, on the one hand, via a series connection of a third capacitor with a first resistance, to the other terminal of said third secondary winding and connected, on the other hand, to the emitter of said transistor, the collector of which is connected to said primary winding; a point between said third capacitor and said first resistance being connected to the cathode of a second diode; said control circuit having nine terminals including a first terminal delivering a reference voltage and connected, via a voltage divider formed of a third and fourth series-connected resistances, to the anode of said second diode; a second terminal of said control circuit serving for zero-crossing identification being connected via a fifth resistance to said cathode of said second diode; a third terminal of said control-circuit serving as actual value input being directly connected to a divider point of said voltage divider forming said connection of said first terminal of said control circuit to said anode of said second diode; a fourth terminal of said control circuit delivering a sawtooth voltage being connected via a sixth resistance to a terminal of said primary winding of said transformer facing away from said transistor; a fifth terminal of said control circuit serving as a protective input being connected, via a seventh resistance to the cathode of said first diode and, through the intermediary of said seventh resistance and an eighth resistance, to the cathode of a third diode having an anode connected to an input of said rectifier circuit; a sixth terminal of said control circuit carrying said reference potential and being connected via a fourth capacitor to said fourth terminal of said control circuit and via a fifth capacitor to the anode of said second diode; a seventh terminal of said control circuit establishing a potential for pulses controlling said transistor being connected directly and an eighth terminal of said control circuit effecting pulse control of the base of said transistor being connected through the intermediary of a ninth resistance to said first capacitor leading to the base of said transistor; and a ninth terminal of said control circuit serving as a power supply input of said control circuit being connected both to the cathode of said first diode as well as via the intermediary of a sixth capacitor to a terminal of said second secondary winding as well as to a terminal of said third secondary winding.

Description:

The invention relates to a blocking oscillator type switching power supply for supplying power to electrical equipment, wherein the primary winding of a transformer, in series with the emitter-collector path of a first bipolar transistor, is connected to a d-c voltage obtained by rectification of a line a-c voltage fed-in via two external supply terminals, and a secondary winding of the transformer is provided for supplying power to the electrical equipment, wherein, furthermore, the first bipolar transistor has a base controlled by the output of a control circuit which is acted upon in turn by the rectified a-c line voltage as actual value and by a set-point transmitter, and wherein a starting circuit for further control of the base of the first bipolar transistor is provided.

Such a blocking oscillator switching power supply is described in the German periodical, "Funkschau" (1975) No. 5, pages 40 to 44. It is well known that the purpose of such a circuit is to supply electronic equipment, for example, a television set, with stabilized and controlled supply voltages. Essential for such switching power supply is a power switching transistor i.e. a bipolar transistor with high switching speed and high reverse voltage. This transistor therefore constitutes an important component of the control element of the control circuit. Furthermore, a high operating frequency and a transformer intended for a high operating frequency are provided, because generally, a thorough separation of the equipment to be supplied from the supply naturally is desired. Such switching power supplies may be constructed either for synchronized or externally controlled operation or for non-synchronized or free-running operation. A blocking converter is understood to be a switching power supply in which power is delivered to the equipment to be supplied only if the switching transistor establishing the connection between the primary coil of the transformer and the rectified a-c voltage is cut off. The power delivered by the line rectifier to the primary coil of the transformer while the switching transistor is open, is interim-stored in the transformer and then delivered to the consumer on the secondary side of the transformer with the switching transistor cut off.

In the blocking converter described in the aforementioned reference in the literature, "Funkschau" (1975), No. 5, Pages 40 to 44, the power switching transistor is connected in the manner defined in the introduction to this application. In addition, a so-called starting circuit is provided. Because several diodes are generally provided in the overall circuit of a blocking oscillator according to the definition provided in the introduction hereto, it is necessary, in order not to damage these diodes, that due to the collector peak current in the case of a short circuit, no excessive stress of these diodes and possibly existing further sensitive circuit parts can occur.

Considering the operation of a blocking oscillator, this means that, in the event of a short circuit, the number of collector current pulses per unit time must be reduced. For this purpose, a control and regulating circuit is provided. Simultaneously, a starting circuit must bring the blocking converter back to normal operation when the equipment is switched on, and after disturbances, for example, in the event of a short circuit. The starting circuit shown in the literature reference "Funkschau" on Page 42 thereof, differs to some extent already from the conventional d-c starting circuits. It is commonly known for all heretofore known blocking oscillator circuits, however, that a thyristor or an equivalent circuit replacing the thyristor is essential for the operation of the control circuit.

It is accordingly an object of the invention to provide another starting circuit. It is a further object of the invention to provide a possible circuit for the control circuit which is particularly well suited for this purpose. It is yet another object of the invention to provide such a power supply which is assured of operation over the entire range of line voltages from 90 to 270 V a-c, while the secondary voltages and secondary load variations between no-load and short circuit are largely constant.

With the foregoing and other objects in view, there is provided, in accordance with the invention, a blocking oscillator-type switching power supply for supplying power to electrical equipment wherein a primary winding of a transformer, in series with an emitter-collector path of a first bipolar transistor, is connected to a d-c voltage obtained by rectification of a line a-c voltage fed-in via two external supply terminals, a secondary winding of the transformer being connectible to the electrical equipment for supplying power thereto, the first bipolar transistor having a base controlled by the output of a control circuit acted upon, in turn, by the rectified a-c line voltage as actual value and by a set-point transmitter, and including a starting circuit for further control of the base of the first bipolar transistor, including a first diode in the starting circuit having an anode directly connected to one of the supply terminals supplied by the a-c line voltage and a cathode connected via a resistor to an input serving to supply power to the control circuit, the input being directly connected to a cathode of a second diode, the second diode having an anode connected to one terminal of another secondary winding of the transformer, the other secondary winding having another terminal connected to the emitter of the first bipolar transmitter.

In accordance with another feature of the invention, there is provided a second bipolar transistor having the same conduction type as that of the first bipolar transistor and connected in the starting circuit with the base thereof connected to a cathode of a semiconductor diode, the semiconductor diode having an anode connected to the emitter of the first bipolar transistor, the second bipolar transistor having a collector connected via a resistor to a cathode of the first diode in the starting circuit, and having an emitter connected to the input serving to supply power to the control circuit and also connected to the cathode of the second diode which is connected to the other secondary winding of the transformer.

In accordance with a further feature of the invention, the base of the second bipolar transistor is connected to a resistor and via the latter to one pole of a first capacitor, the anode of the first diode being connected to the other pole of the first capacitor.

In accordance with an added feature of the invention, the input serving to supply power to the control circuit is connected via a second capacitor to an output of a line rectifier, the output of the line rectifier being directly connected to the emitter of the first bipolar transistor.

In accordance with an additional feature of the invention, the other secondary winding is connected at one end to the emitter of the first bipolar transistor and to a pole of a third capacitor, the third capacitor having another pole connected, on the one hand, via a resistor, to the other end of the other secondary winding and, on the other hand, to a cathode of a third diode, the third diode having an anode connected via a potentiometer to an actual value input of the control circuit and, via a fourth capacitor, to the emitter of the first bipolar transistor.

In accordance with yet another feature of the invention, the control circuit has a control output connected via a fifth capacitor to the base of the first bipolar transistor for conducting to the latter control pulses generated in the control circuit.

In accordance with a concomitant feature of the invention, there is provided a sixth capacitor shunting the emitter-collector path of the first transistor.

Other features which are considered as characteristic for the invention are set forth in the appended claim.

Although the invention is illustrated and described herein as embodied in a blocking oscillator type switching power supply, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.