JPH0352057Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a horizontal output circuit used in a television receiver to display various video signals having different horizontal scanning frequencies.

[Technical background of the invention] The horizontal scanning frequency of television broadcasting currently being broadcast is 15.735KHz in Japan, but this horizontal scanning frequency is not necessarily common throughout the world.
For example, in France, a horizontal scanning frequency of 20.48 KHz is also used in some areas. In addition, when a television receiver is used as part of a wired video system, for example, for a character display, a personal computer display, or a high-definition television monitor, the number of scanning lines for normal television broadcasting is 525. It is often required to have 1000 or more scanning lines, which is even more than a book.

Therefore, there is a need for a television receiver having a horizontal deflection circuit that can be continuously varied to accommodate these various horizontal scanning frequencies. As a means for continuously changing the horizontal scanning frequency in this way, a horizontal deflection circuit as shown in FIG. 2 can be considered. That is, the horizontal synchronization signal is input to input terminal 1.
The signal then enters an FV (frequency-voltage) converter 2 and is converted into a DC voltage proportional to the horizontal scanning frequency. This voltage is input to the horizontal oscillation cycle circuit 3 and becomes a control voltage to control the horizontal oscillation wave number. The horizontal oscillation output is passed through the horizontal drive circuit 4 to the horizontal output transistor 5.
to drive. A damper diode 6 is connected in parallel between the collector and emitter of the horizontal output transistor 5, a resonant capacitor 7 is connected in parallel, and a horizontal deflection coil 8, a horizontal linearity coil 9, and an S-shaped correction capacitor 10 are connected in series. The circuits are connected in parallel, and one end of a flyback transformer primary coil 11 is connected to the collector of the transistor 5. On the other hand, the FV-converted DC voltage described above also controls the supply voltage V _cc of the power supply control circuit 12 that drives the horizontal output transistor 5 . This voltage _Vcc is controlled in direct proportion to the horizontal scanning frequency and is supplied to the other end of the flyback transformer primary coil 11.

FIG. 3 shows the operating waveforms of the horizontal output stage in the above circuit, where a shows the waveform of the collector voltage V _p of the horizontal output transistor 5, and b shows the waveform of the current I _y of the horizontal deflection coil 8. It shows. Furthermore, the solid line in the figure is the waveform for horizontal scanning frequency _H1 , and the broken line is for horizontal scanning frequency _H2 (=2× _H1 ).
This is the waveform for the case. Note that V _cc1 and V _cc2 indicate average voltage levels (AC=0) when the horizontal scanning frequencies are _H1 and _H2 , respectively.

As shown in Figure 3, the horizontal scanning frequency is _H1 .
The flyback period T _r does not change from the case of _H2 and shows a constant period. Therefore, the scanning period T _s
As shown in FIG. 4, H does not have a linear relationship with the horizontal scanning frequency _H , but a nonlinear relationship.

That is, the scanning period for horizontal scanning frequencies _H1 and _H2
The relationship between T _s1 and T _s2 is nonlinear. coil 8,9
When the total series impedance of the deflection coil line is L, the horizontal deflection current I _y is expressed as I _y =(V _cc /L)·T _s . Therefore, if the power supply voltage V _cc and impedance L are constant, the current I _y becomes linear with respect to changes in the scanning period T _s . Since the scanning period T _s is nonlinear with respect to the horizontal scanning frequency _H , in order to keep the horizontal change current I _y constant regardless of the horizontal scanning frequency _H , the voltage V _cc must be adjusted to correct the nonlinear characteristics of the scanning period T _s .
have an inverse nonlinear relationship or the impedance L
It is necessary to make it smaller as the horizontal scanning frequency _H increases. In the former method, in which the power supply voltage V _cc is in an inverse nonlinear relationship, the control circuit for the power supply voltage V _cc is superimposed on the power supply control circuit 12, which not only increases the circuit scale but also increases the collector voltage of the horizontal output transistor 5. The level of the flyback pulse V _p obtained from this also has inverse nonlinear characteristics, so the flyback transformer tertiary winding voltage (high voltage pulse voltage, AFC (automatic frequency control) pulse, etc.)
This increases the variation in image quality, leading to deterioration of the total image quality. For this reason, the latter method is selected in which the impedance L is made smaller with respect to changes in the horizontal scanning frequency _H.

The configuration of a horizontal output circuit using this latter method is shown in FIG. This circuit has a saturable reactor 13 in the deflection coil line of the horizontal output circuit in FIG.
The control coil 15 has a configuration in which a controlled coil 14 is additionally inserted and connected, and the control coil 15 receives a direct current I _p proportional to the horizontal scanning frequency _H from a control current output circuit 16.
is supplied, and when the horizontal scanning frequency _H becomes high, the DC current I _p of the control coil 15 increases, the impedance of the controlled coil 14 decreases, and the deflection current I _y increases. Therefore, it is possible to cancel the drooping characteristic of the horizontal change current I _y that accompanies an increase in the horizontal scanning frequency _H in the circuit of FIG. 2, and to obtain a constant current I _y with respect to changes in the horizontal scanning frequency _H.

FIG. 6 shows the winding structure and winding distribution of the saturable reactor 13. In this figure, the core around which the controlled coil 14 and control coil 15 are wound consists of an E-shaped core 17 and an I-shaped core 18. Controlled coils 14a-14b into which the horizontal deflection current _Iy flows are wound around the central leg of the core 17.
A control coil into which a direct current I _p proportional to the horizontal scanning frequency _H flows into both legs of the core 17 is divided into two equal parts with a number of turns N ₁ . The control coil is divided into two parts, 15a-15c and 15b-15d. The horizontal deflection current I _y generates a magnetic flux 2〓 ₂ in the direction of the arrow in the center leg of the core, and the control DC current I _p supplied to the control coils 15a and 15b causes a magnetic flux 2 〓 2 to be generated in both legs of the core. Magnetic fluxes φ ₁ and φ ₁ are generated in the directions of arrows opposite to each other. In this case, magnetic fluxes φ ₁ and φ ₁ in opposite directions are generated in the center leg of the core so as to cancel each other out, and magnetic fluxes φ ₂ and φ 1 are generated in both side legs, respectively.
φ ₂ is occurring in the same direction. Thereby, by changing the direct current I _p flowing through the control coil, the inductance of the controlled coil is changed and the magnitude of the deflection current I _y is controlled.

[Problems with the Background Art] Incidentally, a horizontal deflection circuit as shown in FIG. 2 in which the number of horizontal scanning lines is continuously changed necessarily requires a saturable reactor 13 as shown in FIGS. 5 and 6. This has the disadvantage that not only the number of parts increases, but also the area occupied on the circuit board increases, resulting in an increase in cost.

[Purpose of the invention] In view of the above points, the purpose of the invention is to simplify the configuration of a deflection coil line in which a horizontal deflection coil, a horizontal linearity coil, and an S-shaped correction coil are connected in series, thereby reducing the number of parts and occupying board space. It is an object of the present invention to provide a horizontal output circuit that can reduce efficiency and increase costs.

[Summary of the invention] This invention is a saturable reactor with an EI type or EE type core used for the deflection coil line of a horizontal output circuit, and the controlled coil is divided into legs on both sides of the core so that the number of turns is asymmetrically distributed. By winding the control coil around the central leg of the core, the saturable reactor has the characteristics of a horizontal linearity coil.

[Embodiments of the invention] Hereinafter, embodiments of the invention will be described based on the drawings.

FIG. 1 is a block diagram showing an embodiment of a saturable reactor used in a horizontal output circuit according to the present invention.

In this figure, saturable reactor 40 has core 4
It is constructed using an EI type core consisting of 1,42, and controlled coils 20a-20 are installed on both legs of the core.
b is divided and wound so that the number of turns distribution is asymmetrical. In other words, the controlled coils 20a-20b are divided windings 20a-20a-20b, each having a number of turns N _A and N _B (N _A <N _B ).
20c and portions 20b-20d are connected in series to allow horizontal deflection current _Iy to flow.
In addition, control coils 30a-30 are installed in the central leg of the core.
b is wound so that a control direct current I _p is passed through it.

In the saturable reactor 40 configured as described above, the controlled coil _{2 is}
0a-20b has its divided coils 20a-20c.
Magnetic flux φ _A is generated in the left leg where is wound, and magnetic flux φ _B is generated in the right leg where split coils 20b-20d are wound.
occurs. The magnetic fluxes φ _A and φ _B have a relationship of φ _A < φ _B due to the imbalance in the number of turns distribution, and the magnetic fluxes φ _A ,
The directions of both φ _B occur in opposite directions. Therefore, magnetic fluxes φ _A and φ _B are generated in opposite directions in the core central leg by the divided coils 20 a - 20 c and 20 b - 20 d of the controlled coils 20 a - 20 b. Furthermore, magnetic flux 2×φ ₃₀ is generated in the direction of the arrow in the control coils 30a-30b by the control DC current I _p . Therefore, control coils 30a-30b
As a result, magnetic fluxes φ ₃₀ and φ ₃₀ are generated in the same direction on both side legs, respectively. From the above, the sum of magnetic fluxes φ _f at the core central leg is φ _f =2φ ₃₀ +(φ _A −φ _B ).

Then, when the horizontal deflection current I _y flows in the direction opposite to that shown in the figure, the directions of the magnetic fluxes φ _A and φ _B also become opposite to those shown in the figure, and the sum of magnetic fluxes φ _r at the core central leg becomes φ _r =
2φ ₃₀ −(φ _A −φ _B ). Since φ _A <φ _B , φ _f
<φ _r , which causes an imbalance in the inductance values of the controlled coils 20a-20b between the first half and the second half of the scanning period. That is, in the first half of the scanning period, the degree of saturation of the central leg of the core decreases (inductance increases), and the rate of change of the horizontal deflection current I _y decreases. In the second half of the scanning period, the degree of saturation of the central leg of the core increases (the inductance decreases), and the rate of change of the horizontal deflection current I _y increases. In other words, it is possible to correct the leftward expansion and rightward contraction tendency of horizontal linearity.
Further, by reversing the balance of the number of turns of the controlled coils 20a and 20b, it is possible to correct the tendency of expansion to the right and contraction to the left.

Although the saturable reactor explained above uses an EI type core, it is also possible to use an EE type core etc.
In the present invention, the value of the turns division ratio of the controlled coil may be set to a predetermined value other than 1 to provide horizontal linearity characteristics.

[Effects of the invention] As described above, according to the invention, the control coil of the saturable reactor used in series connection with the horizontal deflection coil of the horizontal output circuit is divided and wound so that the winding distribution is asymmetrical. With this configuration, the saturable reactor can also have horizontal linearity characteristics. Therefore, when designing a horizontal deflection circuit that can accommodate changes in horizontal scanning frequency, it is possible to reduce the number of components, reduce board occupancy, reduce cost increases, and ultimately improve reliability. It becomes possible to do so.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of a saturable reactor used in a horizontal output circuit according to the present invention;
The figure is a circuit configuration diagram of a conventional horizontal deflection circuit, and FIGS. 3 and 4 are explanatory diagrams explaining the circuit operation of FIG. 2.
FIG. 5 is a circuit diagram of a horizontal output circuit using a conventional saturable reactor, and FIG. 6 is a block diagram of a conventional saturable reactor. 20a-20b...Controlled coil, 20a-2
0c, 20b-20d...Split coil, 30a-
30b...control coil, 40...saturable reactor, 41, 42...core.

Claims (1)

[Claims for Utility Model Registration] An output transformer whose one end is connected to the output end of a power supply circuit capable of controlling the power supply voltage according to the horizontal scanning frequency, and an output transformer connected in parallel between the other end of the output transformer and the ground. A switching element and a resonant capacitor are connected, a horizontal deflection coil and an S-shaped correction capacitor are connected in series between the other end of the output transformer and the ground, and a controlled winding is connected to the horizontal deflection coil and the S-shaped correction capacitor. A reactor that enables changes in the inductance of a deflection coil line by inserting and connecting wires in series, wherein the controlled winding is divided into legs on both sides of an EI or EE type core so that the number of turns is asymmetrically distributed. 1. A horizontal output circuit comprising: a saturable reactor having a control winding wound around the central leg of the core to supply a control current according to a horizontal scanning frequency.