JPH02151177A - Vertical deflection output circuit in vertical frequency system - Google Patents

Abstract

PURPOSE:To utilize a packaged vertical output IC used for a low frequency system by connecting a capacitor in series with a vertical deflection coil and providing a switch means between an output terminal of the vertical output IC and the vertical deflection coil. CONSTITUTION:One terminal of a vertical deflection coil 8 is connected to a collector of a transistor TR 3 and the other terminal is connected to ground via a coupling capacitor 9 and a current sensing resistor 10 connected in series. Since the vertical output IC 2 outputs a voltage pulse of VccX2 in the transit to a retrace period, a base and an emitter of the TR 3 are biased reverse and the TR 3 is turned off, a resonance pulse v is generated by an inductance of the vertical deflection coil 8 and a capacitance of a resonance capacitor 6. Then the resonance pulse v is superimposed on a retrace pulse by the vertical output IC 2 to produce a retrace pulse. Through the simple constitution above, the width of the retrace is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The vertical deflection output circuit in the high vertical frequency system of the present invention will be described in detail according to the following items.

A. Field of industrial application B1 Overview of the invention C0 Background art [Figure 5] D1 Problem to be solved by the invention E6 Means for solving the problem F. Examples [Figures 1 to 4] F- 1. First embodiment [Figures 1 to 3] a0 circuit [
Figure 1] b, Operation [Figures 2 and 3] C1 Effect [Figure 3] F-2, Second embodiment [Figure 4] G1 Effect of the invention (A, industrial application field) The present invention relates to vertical deflection output circuits in novel high vertical frequency systems. Specifically, in systems with high vertical frequencies such as multi-scan and flickerless systems, it is possible to use vertical output ICs used in low vertical frequency systems, reducing costs and board area.
The present invention also attempts to provide a vertical deflection output circuit for a novel high vertical frequency system that can improve power utilization efficiency.

(B. Summary of the Invention) The vertical deflection output circuit in the high vertical frequency system of the present invention connects a capacitor in series to the vertical deflection coil, and also provides a switch means between the vertical deflection coil and the output terminal of the vertical output IC. When the switch means is opened during vertical retrace, a resonant circuit is formed by the vertical deflection coil and the capacitor, and the resonant pulse at this time is superimposed on the output voltage of the vertical output IC and a trace pulse is obtained, resulting in a high vertical frequency. This system allows the use of packaged vertical output ICs used in conventional low vertical frequency systems, reducing costs and board space, and improving power usage efficiency. It is.

(C, Background Art) [Figure 5] In televisions, the electron beam emitted from the electron gun is usually deflected by a deflection coil to draw a raster on the fluorescent screen of the picture tube to project an image. A vertical deflection circuit is provided to generate a sawtooth wave based on a vertical synchronization signal separated from a video signal and to cause a predetermined deflection current to flow through the vertical deflection coil in response to the sawtooth wave.

Figure 5 shows the vertical frequency of 50.6 for PAL, NTSC, etc.
2 schematically shows an example a of a vertical deflection output circuit used in a TV system with a low vertical frequency of about 0.0118.

b is a vertical output IC whose input terminal is connected to the output terminal of a vertical drive circuit (not shown), which receives a sawtooth wave from the vertical drive circuit and simultaneously supplies sufficient deflection power to the vertical deflection coil of the load. It is set up for the purpose of

C is a vertical deflection coil, one end of which is a vertical output IC.
b, and the other end is grounded via a series-connected coupling capacitor d and current detection resistor e. A portion of the deflection current flowing through the vertical deflection coil C is fed back to the vertical drive circuit.

Therefore, the deflection voltage waveform by the vertical deflection output circuit a is a substantially trapezoidal waveform f on which the retrace pulse is superimposed, as shown by the V- in FIG. 2(B) or the broken line in the voltage waveform diagram of FIG. The deflection current waveform becomes a sawtooth wave g as shown by the broken line in the current waveform diagram of FIG.

(D. Problem to be Solved by the Invention) By the way, the circuit a described above is used for a low vertical frequency system, and this circuit a is used for a high vertical frequency (vertical double speed system) such as a multi-scan or flicker-free system. In order to apply it to a deflection) system, it is necessary to reduce the vertical retrace width, and the retrace pulse voltage is about twice as high as that of a low vertical frequency system, so it is said that the withstand voltage of off-the-shelf vertical deflection ICs cannot withstand its use. There's a problem.

Therefore, circuits are usually constructed using discrete elements such as power transistors and passive elements, but this not only increases cost and board area, but also requires a low voltage during the scanning period, but it is difficult to match the retrace pulse. Various problems remain, such as a high power supply voltage is required for the amplifier, low power supply efficiency, and large power loss due to the direct current resistance of the vertical deflection coil.

(E. Means for Solving the Problems) In order to solve the above-mentioned problems, the vertical deflection output circuit in the high vertical frequency system of the present invention connects a capacitor in series with the vertical deflection coil and outputs the output of the vertical output IC. a switch means is provided between the terminal and the vertical deflection coil;
When the switch means is opened during vertical retrace, a series resonant circuit is formed by the vertical deflection coil and the capacitor, and the resonant pulse at this time is superimposed on the output voltage of the vertical output IC to obtain the retrace pulse. be.

Therefore, according to the present invention, since it is possible to use a packaged vertical output IC used in a low frequency system, there is no increase in cost or board area, and moreover, it is possible to use a packaged vertical output IC used in a low frequency system. Since the resonant pulse caused by the combination of the deflection coil's inductance and the capacitor's capacitance is superimposed on the output voltage of the vertical output RC, a high power supply voltage for the amplifier is not required, and the vertical output IC can be driven. The voltage is sufficient and the efficiency of power usage is high, which can reduce power consumption.

(F. Embodiment) [FIGS. 1 to 4] Details of the vertical deflection output circuit in the high vertical frequency system of the present invention will be described below according to the illustrated embodiments.

(F-1, First Embodiment) [Figures 1 to 3] Figures 1 to 3 show the circuit configuration and operation of the first embodiment of the vertical deflection output circuit in the high vertical frequency system of the present invention. This shows that.

(a, circuit) [Figure 1] 1 is a vertical deflection output circuit.

2 is a vertical output IC used in normal low vertical frequency systems, and is a class B vertical output circuit (SEPP circuit, 5RP
P circuit, etc.), pump-up circuit, and return switch in an IC package. And vertical output IC2
The sawtooth wave that is waveform-shaped and amplified by a vertical drive circuit (not shown) and sent is manually input, and a push-pull operation is performed accordingly. Note that one of the power supply terminals of the vertical output IC 2 is connected to a power supply terminal of a constant voltage power supply circuit (this power supply voltage is defined as vee (v)), not shown.
The other side is grounded, and the vertical output IC 2 outputs a pump-up voltage approximately twice as high as vcc during the vertical retrace period by its pump-up circuit.

3 is a switching NPN transistor, the emitter of which is connected to the output terminal of the vertical output IC 2.

A diode 4 is provided to increase reverse breakdown voltage between the base and emitter of the transistor 3, and its cathode is connected to the base of the transistor 3, and its anode is connected to the power supply terminal via the base resistor 5. has been done.

Reference numeral 6 denotes a resonant capacitor, which is provided between the collector and emitter of the transistor 3, and is connected in series to a vertical deflection coil, which will be described later.

7 is a damper diode, the anode of which is connected to the emitter of the transistor 3, and the cathode connected to the collector.

8 is a vertical deflection coil, one end of which is connected to the transistor 3.
The other end is grounded via a coupling capacitor 9 and a current detection resistor 10 connected in series. A portion of the deflection current is also fed back to the vertical drive circuit.

(b. Operation) [FIGS. 2 and 3] The operation of the vertical deflection output circuit 1 described above is performed as follows. Note that FIG. 2(A) shows an equivalent circuit of the vertical deflection output circuit 1, and the function of the transistor 3 is represented by a switch symbol, and FIG. 2(B) shows a schematic operating waveform diagram. In both figures, V is the output voltage of the vertical output IC2, ■ is the deflection current, ■ is the resonance pulse, and Ipp in Figure 2 (B) is the pp value of the deflection current,
Vp indicates the peak voltage of the resonance pulse, and tp indicates the resonance pulse width. In addition, FIG. 3 schematically shows waveforms centered around the deflection voltage and current trace period,
In the figure, tr indicates a retrace period, and tt indicates a trace period. Furthermore, in the waveform diagram showing the deflection current, the two-dot chain line represents the reference sawtooth wave 11, the one-dot chain line represents the damped oscillation curve 12 due to the DC resistance of the vertical deflection coil, and the curves 13 and 13' represent the reference sawtooth wave 11. It represents an envelope (exponential function curve) connecting the peak values of the damped vibration curve 12.

First, during the vertical trace period, the output voltage of the vertical output IC is low and the transistor 3 is in an on state, and the deflection current I decreases linearly from positive to negative, and becomes a negative current in the latter half.

Then, when moving to the retrace section, vertical output IC2
outputs a voltage pulse of ■cc×2, so the voltage between the base and emitter of transistor 3 and the cap becomes reverse N and turns off, which resonates with the inductance of vertical deflection coil 8 (this is referred to as Lv (H)). A resonance pulse is generated due to the capacitance of the capacitor 6 (this is referred to as Cc (F)). The resonance pulse width 1p at this time is the resonance frequency f
= 2π・(Lv −Ce)−”’ to 1/half wave
It is approximately p−π·(Lv·Cc) l/2. Also,
The peak value 2 is the electromagnetic energy stored in the vertical deflection coil 8 -X LV Electrostatic energy - x Cc x vp' is considered to be equal, and ■2 ==× Ipp× (shi, / c c) l/
It will be about 2.

Then, this resonance pulse V is superimposed on the retrace pulse (pulse width tr, voltage cc×2) from the vertical output IC 2, and a trace pulse as shown in FIG. 3 is generated.

Also, the deflection current waveform! Ideally, it should reach from the negative current peak point P- to the positive current peak point P0 in the reference sawtooth wave 11 immediately after the resonance ends, but it is shown in FIG. 3 because of attenuation due to the DC resistance of the vertical deflection coil 8. It only reaches point A.

What compensates for the current shortage from point A to point B on the reference sawtooth wave is the vertical output IC 2 vertical trace voltage ccx2 during the period 1.
-1p depends on the resonance Q value.

(c, operation) [Fig. 3] When the retrace pulse and deflection current of the vertical deflection output circuit 1 described above are compared with those f and g of the conventional vertical deflection output circuit a, the difference in operation becomes even clearer. become.

That is, in the conventional circuit a, the peak voltage value of the beam trace pulse is constant (ce At the beginning of the retrace period in the voltage waveform, that is, during the period tp, the resonance pulse ■
occurs, which causes the deflection current to return to its starting point P
- After reaching the sharp rise point A, the period t, -t''
, the waveform is defined by the reference sawtooth wave 11 by the vcC×2 glue trace pulse from the vertical output IC, and after reaching the target point B of the current value, the waveform follows the reference sawtooth wave 11.

As described above, the vertical deflection output circuit 1 uses the vertical output IC 2 used in a low vertical frequency system, generates a resonant pulse during the vertical retrace period, and converts this into the output voltage Vcc×2 of the vertical output IC 2. Since they are overlapped, the retrace width can be shortened with a simple configuration, and there is no increase in costs, and the supply voltage is only enough to drive the vertical output IC2, reducing power usage efficiency. There is no invitation.

(F-2, Second Embodiment) [FIG. 4] FIG. 4 shows a second embodiment IA of the vertical deflection output circuit in the high vertical frequency system of the present invention.

The difference between the vertical deflection output circuit IA in the high vertical frequency system shown in this second embodiment and the vertical deflection output circuit 1 in the high vertical frequency system shown in the first embodiment is that an FET is used as a switch element. Therefore, explanations regarding basic operations and effects will be omitted, and in explanations regarding parts that are structurally the same, the same reference numerals used for similar parts in the first embodiment will be used for each part. It is omitted by attaching it.

14 is an FET whose source is connected to the output terminal of the vertical output IC 2 and whose drain is connected to one end of the vertical deflection coil 8. The gate of the FET 14 is connected to a power supply terminal via a resistor 15, and two Zener diodes 16.1 are connected between the gate and the source.
6' is inserted. In addition, damper diode 7 is FE
It is provided between the drain and source of T14.

According to the vertical deflection output circuit IA, FET14
The current is smoothly taken over at the switching timing between the damper diode 7 and the damper diode 7, and it is possible to prevent a horizontal seam from occurring near the center of the screen.

(G. Effect of the invention) As is clear from the above description, the vertical deflection output circuit in the high vertical frequency system of the present invention includes a capacitor connected in series to the vertical deflection coil, and a predetermined sawtooth waveform applied to the vertical deflection coil. A switch means is provided between the output terminal of the vertical output IC for flowing current and the vertical deflection coil to form a resonant circuit between the capacitor and the vertical deflection coil during the vertical retrace period, and during the vertical retrace period, When the switch means is opened, a resonant circuit is formed with the vertical deflection coil and the capacitor;
The present invention is characterized in that the resonance pulse at this time is superimposed on the output voltage of the vertical output IC to obtain a retrace pulse.

Therefore, according to the present invention, since it is possible to use a packaged vertical output IC used in a low frequency system, there is no increase in cost or board area, and moreover, it is possible to use a packaged vertical output IC used in a low frequency system. Since the resonant pulse caused by the coupling between the inductance of the deflection coil and the capacitance of the capacitor is superimposed on the output voltage of the vertical output IC, a high power supply voltage for the amplifier is not required and the vertical output IC can be driven. Voltage is sufficient, and the efficiency of power usage is high, making it possible to reduce power consumption.

Incidentally, in the second embodiment described above, the FE is used as the switch means.
T is used, but this prevents the inconvenience of horizontal seams appearing near the center of the screen.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of a vertical deflection output circuit in a high vertical frequency system of the present invention,
FIG. 1 is a circuit diagram, FIG. 2 is a diagram for explaining circuit operation, (A) is an equivalent circuit diagram, (B) is an operation waveform diagram, and FIG. 3 is a deflection voltage waveform and diagram according to the present invention. FIG. 4 is a circuit diagram showing the second embodiment of the vertical deflection output circuit in the high vertical frequency system of the present invention; FIG. 5 is the conventional vertical deflection output FIG. 2 is a circuit diagram showing an example of a circuit. Explanation of symbols 1... Vertical deflection output circuit in a high vertical frequency system, 2... ICl for vertical output, 3... Switch means, 6... Capacitor, 8... Vertical deflection coil, IA... Vertical deflection output circuit in high vertical frequency system, 14...Switch means circuit diagram Example of big lips) Nashi A FM 1

Claims (1)

[Claims] A capacitor connected in series to the vertical deflection coil is inserted between the output terminal of a vertical output IC for passing a predetermined sawtooth wave current to the vertical deflection coil, and the vertical deflection coil. A switch means is provided to form a resonant circuit with the deflection coil, and when the switch means is opened during the vertical retrace period, a resonant circuit with the vertical deflection coil and the capacitor is formed, and the resonant pulse at this time is used for vertical output. A vertical deflection output circuit in a high vertical frequency system, characterized in that a retrace pulse is obtained by being superimposed on the output voltage of an IC.