DE1927501A1 - Circuit arrangement for convergence adjustment in multi-standard color television receivers - Google Patents

Description

BLAUPUNKT-WERKE GMBH, * h.lde.he.m. »*« *. * ■ «» ■. * »

R.No. 1040 May 28, 1969

PLI Uh / Fo

Circuit arrangement for convergence adjustment in multi-standard color television receivers

The invention relates to a circuit arrangement for convergence adjustment in the case of multi-standard color television receivers with a three-beam color picture tube for standards with different line frequencies, whereby to set the static convergence convergence coil ^ n lie in a circuit with variable direct current and the magnetic field of the convergence coils through a permanent magnet can be influenced.

In multi-standard devices of this type, the changeover to a different line frequency also changes the static convergence, which means that when the line output stage is changed over, a changed setting of the static convergence is also required. In color television receivers for a line frequency, both variable permanent magnets and convergence coils which can be adjusted by means of a variable direct current are known for setting the static convergence. Since a mechanical change in two setting states, as would be required with multi-standard receivers with permanent magnet setting, is difficult, separate adjustable DC circuits are provided for the convergence coils in known multi-standard receivers, which are usually connected to the convergence coils via relay switching contacts. This is associated with considerable additional effort and requires a stable DC voltage source that produces the same convergence current as possible even after prolonged use of the device.

These disadvantages can be avoided if according to the invention permanent magnets arranged in a finely adjustable position in front of

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R.No. 1040 - 2 - May 28, 1969

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are seen with which the setting of the static convergence at a first line frequency is possible int, and if for the setting of the static convergence at a second cell frequency convergence coils are provided which can be changed Subcircuits are located in a Gesaratstromkreis are summarized in which a switch is arranged, which interrupts the entire circuit when the receiver is on reception at the first line frequency is set. Here, the convergence setting for a line frequency takes place first with the permanent magnets, the convergence coils being switched off by the open switch. To after switching to the second line frequency, the setting made first remains in effect and serves as a Basic setting for convergence at the second line frequency. The setting for this is made via the convergence coils, with which only the errors in the switchover are corrected Need to become. A particularly advantageous circuit results when the convergence coils are in the shunt arm of a resistance bridge circuit lie, a series branch of the bridge circuit contains a potentiometer, at whose tap the convergence coils are connected, the series branches with one end to ground and with the other end via a common Line are at the pole of an operating voltage source and a switch is provided in the common line, which has a Norm switch is operated. With such a bridge arrangement, the total current changes when the setting is changed only slightly and the current direction can also be changed using a simple potentiometer when setting will.

The invention is explained in more detail using an exemplary embodiment shown in the drawing.

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R.No. 1040 - 3 - May 28, 1969

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1 shows the circuit arrangement of the static converter _ genz and

2 shows the construction of a convergence device for one of the three electron beams in principle. '

On the neck of the picture tube 1 of a three-beam color picture tube are the three Electron beams 2 in a known manner three convergence devices associated with a ferrite core with two L-shaped Have core halves 3, 4, one leg end in each case resting on the neck of the picture tube. The other ends of the legs are on top of each other trimmed and separated from one another by an air gap 5. About this air gap 5 is a permanent magnet 6, the circular disk-shaped and radially magnetized lot. The permanent magnet is rotatably mounted, whereby a rotation through 180 ° via one of the legs 4 or 5 the north or south pole acts more strongly. This causes a variable magnetic field at the leg ends, which rest on the neck of the picture tube 1. Wear the legs 3t 4 of the core in addition to the coils 7, 8 for dynamic horizontal and vertical convection, a coil 9 for static convergence.

The coil 9 lies in the shunt arm of a bridge circuit, whose a series branch consists of two series-connected resistors 10, 11, one end of which is connected to ground, the connection point of which 12 is connected to one end of the coil 9 and the other end of which is connected to a potentiometer 13, which forms the second longitudinal branch. The other end of this potentiometer is also connected to Hasse, while the grinder at the other end of the coil 9 is connected. The connection 14 of the two length branches is on via a switch 15 the positive pole of a stabilized operating voltage source placed and at the connection of two longitudinal branches of a second

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R.No. 1040 - 4 - May 28, 1969

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Bridge circuit connected, which consists of resistors 16, and 18, 19. The other ends of these branches lie at the ends of a potentiometer 20, the wiper of which is connected to ground. The connection points 21 and 22 of the series branch resistors 16, 17 and 18, 19 are about the series connection of the other two. Coils 23 and 24 for static convergence adjustment of the other two electron beams connected to each other. The connection point 25 of these two coils 23, 24 is above a resistor 26 on the wiper of a second potentiometer 27, which has one end to ground and the other end to the Connection line 14, which leads to switch 15, is located.

The setting of the static convergence now takes place first with the switch 15 open, which is mechanically or electrically connected as a relay contact to a switching device that serves as a standard switch, the switch 15 being open at a first line frequency for e.g. 819 lines per image. In this case, no current flows through the coils 9, 23, 24 and the magnetic field of the convergence device is only determined by the position of the permanent magnets 6. Once the convergence setting has been made for the first line frequency, a switch is made to the second line frequency, the switch 15 closing. A direct current now flows through the longitudinal members of the two bridge switching points, with no current flowing through the coils 9, 23, 24 when the bridge is balanced and the potentiometer settings are approximately in the middle. The position of the potentiometer 13 is used to correct the errors that arise during the switchover (which can arise, for example, from the fact that a higher operating voltage is used in the deflection at the increased line frequency in order to be able to compensate for the increased inductance at the higher frequency) , 20, 26 changed accordingly * Since the basic correction has already been made with the first setting , only a subsequent correction is required with

009851/0897

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llR.No. 1040 - 5 - May 28, 1969

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! small currents through the coils 9, 25, 24 required, the only marginally affect the total current ¹ of the bridge. At the same time, voltage fluctuations cannot cause any major errors, since the basic correction by the permanent magnets 6 bell remains and only the post-correction is influenced as a percentage of the voltage change.

009851/0897

Claims (2)

Claims Circuit arrangement for convergence adjustment in multi-standard color television receivers with a three-beam color picture tube for standards with different line frequencies, whereby for setting the static convergence convergence coils are in a circuit with variable direct current and that The magnetic field of the convergence coils can be influenced by a permanent magnet, characterized in that in their Position f * an adjustable permanent magnet (6) is provided are, with which the setting of the static convergence is possible at a first line frequency, and that for setting the static convergence at a second line frequency convergence coils (9, 23, 24) are provided are, which are in changeable sub-circuits, which are combined in a total circuit in the one Switch 15 is arranged, which interrupts the entire circuit when the receiver on a reception with the first Line frequency is set. 2. Circuit arrangement according to claim 1, characterized in that a convergence coil (9) in the shunt arm of a resistance bridge shell tüng lies, a series branch of the bridge circuit contains a potentiometer (13), at whose tap the convergence coil (9) is connected, the series branches with one end to ground and with the other end via a line to Pole of an operating voltage source and a switch (15) is provided in the line, which is controlled by a standard switch is operated. 009851/0897