Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
  • H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
  • H04N3/16—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by deflecting electron beam in cathode-ray tube, e.g. scanning corrections
  • H04N3/22—Circuits for controlling dimensions, shape or centering of picture on screen
  • H04N3/223—Controlling dimensions

Definitions

• the invention relates to a method for eliminating volume-dependent changes in image size, in particular of color television sets with I10 ° deflection picture tubes, preferably for use in devices with high sound power, the circuits of the device being operated with supply voltages stabilized via switching power supplies, the pillow distortion of the 110 ° deflection
• the picture tube is set by active east-west raster correction.
• the invention further relates to a circuit arrangement for performing the method, with stabilized switching power supply, horizontal switching circuit and Ver tikal deflection circuit, wherein an east-west correction circuit is connected to the horizontal deflection circuit, which has an amplifier.
• a circuit arrangement for performing the method with stabilized switching power supply, horizontal switching circuit and Ver tikal deflection circuit, wherein an east-west correction circuit is connected to the horizontal deflection circuit, which has an amplifier.
• the stability of the power supply unit of the device and thus those of its supply voltages are improved compared to the changing sound load. It would be desirable to keep the approximately 150 V supply voltage of the horizontal deflection circuit stable within 0.1 V, while the tone stage receives a load that changes from zero to 2-3 amperes at a supply voltage of 20 V, for example.
• the switching power supply that secures the separation and is based on the integrated circuit of the TDA 4600 type from the manufacturer SIEMENS has proven and spread best in terms of efficiency, reliability and economy, according to information from SIEMENS, this switching power supply has so far found in more than 20 million telecommunications devices.
• Substantially better stability parameters are characteristic of the circuit arrangement shown in the above-mentioned edition on page 32, which realizes the required voltage stability by monitoring the secondary voltage and by using further active and passive components by separate feedback control on the primary side.
• a solution described in DE-PS 2 749 847 has also set itself the goal of eliminating the crosstalk caused by the changes in volume.
• the essence of this solution is that in the transformer of the power supply, the coupling of the winding feeding the sound output stage with the control winding is designed as a fixed coupling, while the winding feeding the horizontal deflection circuit is designed as a loose coupling.
• a disadvantage of this solution is that it requires a specially constructed transformer, the uniform production of which is associated with difficulties and an optimal effect which dampens the crosstalk values can only be achieved with a predetermined load and mains voltage.
• the supply voltage is no longer sufficiently stable due to the loose coupling of the supply voltage winding of the horizontal deflection circuit to the control winding, as a result of which high-voltage and image size stability problems can also occur.
• the aim of the invention is to develop a method and a circuit arrangement used to carry out this method, which make it possible, using the well-proven stabilized switching power supplies in any range of the beam current and volume, to keep the changes in image size caused by volume changes within permitted limits .
• the inventive concept is based on the knowledge that instead of improving the crosstalk values, the
• the method according to the invention for eliminating volume-dependent changes in picture size, in particular of color television sets with 110 ° deflection picture tubes, preferably for use in devices with high sound power, - in the course of which the circuits of the device are operated by supply voltages stabilized by means of switching power supplies is set via an active east-west raster correction - on the fact that the change in picture width occurring as a result of the change in the supply voltage of the horizontal deflection circuit by means of a signal obtained from the change in supply voltage of the horizontal deflection circuit via the
• East-west correction circuit is compensated by regulating the horizontal size.
• the circuit arrangement according to the invention for eliminating volume-dependent changes in image size. especially of color television sets with 110 ° deflection picture tubes, preferably for use in devices with high sound power, - which is provided with a stabilized switching power supply, horizontal deflection circuit, United tical deflection circuit, with the horizontal deflection Circuit an east-west correction circuit has an amplifier - is designed such that a compensation network is inserted via a diode between the supply voltage terminal of the horizontal deflection circuit and the input of the amplifier of the east-west correction circuit.
• Another feature of the invention can consist in that the compensation network is formed by a passive compensation network which has at least one Zener diode and resistor connected in series with one another.
• an NTC resistor suitable for compensating for the change in temperature is connected in series and / or in parallel with the Zener diode.
• the compensation network is formed by an active compensation network provided with a primary power source, between the input and the earth of which a primary power source connected in series with a resistor, and optionally a resistor connected in parallel with the primary power source, are connected, while the common switching point of the Resistor and the primary power source is connected via an inserted impedance converter to the output of the active compensation network provided with primary power source (current generator).
• the compensation network is formed by an active compensation network provided with an operational amplifier, between the input and the earth of which a resistance divider is connected, while between the center of the resistance divider and the output of the compensation network provided with an operational amplifier, an operational amplifier with preferably variable amplification is connected.
• the supply voltage terminal of the vertical deflection circuit can be connected to the rectifier, which is connected to the line transformer winding of the horizontal deflection circuit.
• the most important advantage of the method according to the invention and the circuit arrangement according to the invention is that their use can reduce the volume-dependent change in image size to a minimum dimension that is no longer perceptible to the viewer. Another advantage is that the invention does not require any major intervention in the circuits of the device, but can be implemented by installing only a few simple components. The invention is explained in more detail below by means of examples with reference to the accompanying drawing.
• FIG. 2 shows a possible embodiment of the circuit arrangement according to the invention in an east-west correction circuit constructed from discrete components
• 3 shows another embodiment of the circuit arrangement according to the invention in an east-west correction circuit constructed with an integrated circuit
• Fig. 4 shows a possible embodiment of an active
• FIG. 5 shows a further embodiment of the active compensation network.
• 1 shows a general block diagram of the circuit arrangement according to the invention, according to which a supply voltage terminal 21 of a horizontal deflection circuit 2 is connected to a stabilized switching power supply 1.
• An east-west correction circuit 4 is connected to the horizontal deflection circuit 2.
• the east-west correction circuit 4 has an amplifier 41, a compensation circuit 5 being inserted between the input 41a of the amplifier 41 and the supply voltage terminal 21 of the horizontal deflection circuit 2.
• the supply voltage terminal 31 of a vertical deflection circuit 3 is connected to a rectifier 23 of the horizontal deflection circuit 2, the rectifier 23 being connected to a line transformer winding 22 of the horizontal deflection circuit 2.
• FIG. 2 illustrates a possible embodiment of the circuit arrangement according to the invention, in which the east-west correction circuit 4 is constructed from discrete components.
• the east-west correction circuit 4 is provided with the amplifier 41, the input 41a of which is connected via a potentiometer 4b for image width and a potentiometer 4a to a deforming circuit 54 for vertical parabola correction.
• the raster correction circuit is a known circuit, its design according to the invention essentially consists in the insertion of a passive compensation network 51.
• the supply voltage terminal 21 of the horizontal deflection circuit 2 is connected via a resistor 51b, Zener diodes 51a and a potentiometer 4a, ei which regulates the size of the parabola signal
• a potentiometer 4b for picture width and a divider 4c is connected to earth, the input 41a of the amplifier 41 being connected to the center tap of the potentiometer 4b for picture width.
• the passive compensation network 51 of the embodiment shown in FIG. 2 has two Zener diodes 51a and the resistor 51b connected in series.
• FIG. 3 illustrates another possible embodiment of the circuit arrangement according to the invention, in which the east-west correction circuit 4 is constructed from an integrated circuit 42, for example of the type TDA 4950 or TDA 8145, the eighth connection (8th pin) of the input 41a of the amplifier 41 forms. Since the integrated circuit 42 operates in switching mode, line frequency pulses are also required, which are supplied by the line transformer winding 24.
• the east-west correction circuit 4 is constructed from an integrated circuit 42, for example of the type TDA 4950 or TDA 8145
• the eighth connection (8th pin) of the input 41a of the amplifier 41 forms. Since the integrated circuit 42 operates in switching mode, line frequency pulses are also required, which are supplied by the line transformer winding 24.
• the size of the pulses is determined by a network formed from a resistor 45, a potentiometer 44 and a limiter zener diode 43.
• the one with Telabgriff of the potentiometer 44 is connected to the input 41 a of the amplifier 41 via a rectifier element, which consists of a diode 46 and a capacitor 47.
• the compensation network 5 is formed by a passive compensation network 51, which is connected between the supply voltage terminal 21 and the common switching point of the center tap of the potentiometer 44 and the diode 46.
• the passive compensation network 51 contains a Zener diode 51a and a resistor 51b, which are connected in series with one another.
• An NTC resistor 51c is connected in parallel with the Zener diode 51a.
• FIG. 4 shows a further embodiment of the invention, in which the compensation network 5 is formed by an active compensation network 52 with a primary power source, a resistor 52a and primary power source 52b connected in series with one another between the input of the active compensation network 52 and the earth, and one with the primary power source 52b connected in parallel resistor 52d.
• An impedance converter 52c is connected between the common switching point of the resistor 52a and the primary current source 52b and the output of the active compensation network 52 provided with the primary current source
• FIG. 5 illustrates a further embodiment of the invention, in which the compensation network 5 is formed by an active compensation network 53 with an operational amplifier.
• the active compensation network 53 with operational amplifier is provided with a resistance divider 53a connected between its input and the ground.
• the switching point of the resistor divider 53a is the Input of an operational amplifier 53b connected with a preferably variable gain.
• the operational amplifier 53b is provided with resistors 53c and 53d for adjusting the amplifier.
• the output of the active compensation network 53 provided with an operational amplifier is formed by the output of the operational amplifier 53b.
• the supply voltage supplied by the stabilized switching power supply 1 changes at the supply voltage terminal 21 of the horizontal deflection circuit 2 in time with the volume changes.
• a decreasing supply voltage causes an image size reduction.
• the amplifier 41 of the east-west correction circuit 4 has a structure such that a voltage reduction at its input 41a causes the image size to be enlarged. However, if this effect is reversed in the case of a circuit with a different structure, then a corresponding phase reversal must be provided in this case.
• the compensation network 5 forwards the signal obtained from the decreasing supply voltage occurring at the supply voltage terminal 21 to the input 41a of the amplifier 41 of the east-west correction circuit 4, as a result of which the image width is increased.
• the compensation network 5 is to be dimensioned in such a way that the picture width reducing effect of the supply voltage decreasing at the supply voltage terminal 21 is compensated (compensated) by the picture width increasing effect of the amplifier 41. Measurements of the east-west correction circuit 4 shown in FIG.
• the first Zener diode 51a connected to the potentiometer 4a was formed by a preferably 12V-Z diode, while the second Zener diode 51a connected to the resistor 51b was formed below the Zener diodes 51a was formed by a 110V Z diode, the value of resistor 51b being 330 ohms.
• a 680nF capacitor was used as a coupling capacitor 4d, a 100nF capacitor as a filter capacitor 4s, a 4.7 k0hm potentiometer as a potentiometer 4a, a 100 k0hm potentiometer as an image width potentiometer and 4c sin as a resistor
• the potentiometer 44 had a value of 10 k0hm
• the resistor 45 connected in series with it had a value of 1.5 k0hm
• the Zener diode 51a was a diode of the ZY-120 type
• the resistor 51b had a value of 8.2 k0hm.
• the temperature dependence of the Zener diode / the Zener diodes 51a must also be taken into account.
• the temperature coefficient of the 110V Zener diode used in the circuit according to FIG. 2 is 0.1% / ° C. If the circuit arrangement according to the invention with such a Zener diode is now installed in a device and the device is exposed to a temperature change of 15 ° C. the image size change is less than 2%, which is an acceptable value.
• temperature compensation may be required, which can be achieved with the aid of an NTC resistor 51c connected in series with the Zener diode 51a or in parallel therewith.
• Zener diode it is also possible to use a plurality of Zener diodes connected in series with a lower voltage or a circuit which couples the changes in the supply voltage of the supply voltage terminal 21 into the input 41a of the amplifier.
• a circuit is, for example, the solution illustrated in FIG. 5, in which a resistance divider 53a connected to the supply voltage terminal 21 attenuates the change in the supply voltage and the operational amplifier 53b connected to it amplifies the attenuated signal at the input 41a of the amplifier 41 back to the required level.
• this object can also be achieved with the aid of such a divider according to FIG. 4, the lower link of which is a primary current source 52b consisting of an active element, to the divider an impedance converter 52c, which also contains an active element and is provided with an emitter follower, is connected.
• the attenuation required for compensation can be set with the help of resistors 52a and 52d.
• the method according to the invention and the circuit arrangement according to the invention can preferably be used to eliminate the image size changes caused by changes in volume in all such colors visual devices are used, which are provided with an active east-west raster correction.

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• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Details Of Television Scanning (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 1988
  • 1988-09-02 HU HU453088A patent/HU200049B/hu not_active IP Right Cessation
• 1989
  • 1989-09-01 WO PCT/HU1989/000045 patent/WO1990003079A1/de not_active Application Discontinuation
  • 1989-09-01 CS CS895099A patent/CS509989A2/cs unknown
  • 1989-09-01 EP EP19890910173 patent/EP0386217A1/de not_active Withdrawn
  • 1989-09-01 DD DD33230789A patent/DD284322A5/de not_active IP Right Cessation

Non-Patent Citations (1)

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