JPS60145771A - Horizontal deflecting circuit - Google Patents

Abstract

PURPOSE:To make ringing generated in fly-back voltage and resonance current small by providing a device that suppresses abrupt change of current of resonance current and improving high frequency nonlinearity of deflecting current. CONSTITUTION:When a transistor 2 makes switching action by a square wave signal generator 1, high voltage is generated in primary side of a transformer T1, and large current flows in secondary side winding. This current saturates a transistor 3. Then, the latter half of deflecting current I'D is let flow in a deflecting yoke 6. After sweeping for a fixed period, the transistor 3 becomes off, and fly-back voltage A' is generated. Resonance current I'R repeats oscillation for a fixed period influenced by dynamic characteristic when a damper diode 5 is on. To suppress this oscillation in an early stage, an inductance element 7 is inserted in a resonance capacitor 4 in series.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a horizontal deflection circuit used in a monitor display using an electromagnetic deflection type CRT as display means.

Conventional Structure and Problems Therein FIG. 1 shows a conventional horizontal deflection circuit. The configuration of this conventional example will be explained below with reference to FIG. 1.

In FIG. 1, 1 is a square wave signal generator for switching transistor 2, which has a constant period determined by the horizontal synchronization pulse. T1 is a transformer that supplies enough base current to switch the next-stage switching transistor 3. The collector of the switching transistor 3 is connected to the deflection yoke 6. The capacitor 4 forms a resonant circuit with the inductance of the deflection yoke 6. The diode 6 has its cathode connected to the collector of the switching transistor 3, and its anode side grounded.

Next, the operation of the above conventional example will be explained. In FIG. 1, when transistor 2 performs a switching operation, a large flyback voltage is generated on the primary side of transformer T1.

The peak-to-peak value of this generated voltage is V p , the current value is ip, the secondary side voltage is V s and the current is 18. pressure gauge,
When the turns ratio of T1 is n:1 and it is considered as an ideal transformer, the following relationship holds true. As a result, 't' on the secondary side
l&td·1s=ni, and a base current of the transistor 3 sufficient to generate a p deflection current to be supplied to the deflection yoke is obtained. The transformer T1 thus functions as two types of voltage-current converters, and can obtain a large current with a simple configuration.

Next, let us consider the value of the +/- current using the deflection current of a 2Q-inch CRT as an example. 0 Let the deflection current required to sweep between both ends of the screen in the horizontal direction be p, and the deflection yoke 6 Let L be the inductance of . From the following relationship, if L and TD have predetermined values, T will be small. In other words, as the deflection frequency increases, it is required to increase the supply voltage vp.0 This means that the flyback voltage increases, and therefore, the transistor 3 has a high withstand voltage and a large current capacity. 1OA from o where constraints are imposed.

Set the flyback voltage to 1. If it is about ooov, then hFBH = about 10 at most as a transistor, and therefore the base current requires a minimum of (ID/2)/hB-E=sA/10=O, esA. For this reason, a switching drive system using a transformer can be an effective means.

Next, the generated flyback voltage is a sine wave voltage centered on the c potential, but when it crosses the Q potential and begins to go in the negative direction, the damper diode 6 starts to turn on, and almost the first half of the deflection current Ip is turned on. It functions to direct the flow to the deflection yoke.

At the same time, the flyback voltage is suppressed to a waveform of approximately zero potential or higher, as shown in A of FIG. The transistor 3 and damper diode 5 are off during the flyback voltage generation period, allowing a resonant current R to flow between the resonant capacitor 4 and the deflection yoke 6.

However, the waveform shown in Fig. 2 is applicable in ideal operation, and in reality, as shown in Fig. 3, the flyback voltage A and the resonant current RI/'i cause ringing and deflection. The effect is also apparent in the current.

As a result, a vertical draft can be seen near the left end of the pattern displayed on the screen (the side where the horizontal sweep starts). This phenomenon is particularly noticeable in monitor display devices with a high horizontal deflection frequency. This depends on the performance of a high-speed damper diode that can withstand high flyback voltages and large currents as mentioned earlier, and unless an ideal high-speed damper diode exists, it is conventionally impossible to eliminate this phenomenon. It was difficult.

OBJECTS OF THE INVENTION The present invention eliminates the drawbacks of the above-mentioned conventional examples, and aims to improve the image quality of the tube surface by suppressing the ringing generated in the flyback voltage and resonance current.

Structure of the Invention In order to achieve the above object, the present invention provides means for suppressing rapid current changes in the resonance current, thereby obtaining the effect of improving high-frequency nonlinearity of the deflection current.

DESCRIPTION OF EMBODIMENTS The structure of an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 4, reference numeral 1 denotes a square wave signal generator for switching transistor 2ff, and a transformer T1 is connected to the collector of transistor 2. transformer T1
The secondary side of is connected to the base of transistor 3.

There is no difference in these respects from the conventional example shown in FIG. A deflection yoke 6 is attached to the collector of the transistor 3.
, one of the resonant capacitors 4 and the cathode of the damper diode 6 are connected. The other side of the deflection yoke 6 is connected to the power supply ■c, and the current value ID flowing to the deflection yoke 6 is
/Determine. The anode of damper diode 5 is grounded. The other end of the resonant capacitor 4 is grounded via the inductance element 7. Next, the operation of the above embodiment will be explained. In FIG. 4, when the transistor 2 performs a switching operation by the square wave signal generator 1, a large current flows through the secondary winding due to the high voltage generated on the primary side of the transformer T1. There must be enough forward current to saturate the current, and enough reverse current to bring it to cutoff. When the transistor 3 is turned on, the latter half of the deflection current ID' as shown in FIG. 6 flows through the deflection yoke 6.

After sweeping for a certain period of time, transistor 3 is turned off and flyback voltage A' is generated. As mentioned in the conventional example, when the flyback voltage ends, the resonant current IR' becomes zero, but due to the influence of the dynamic characteristics of the damper diode 6 when it is on, the flyback voltage A' becomes more negative than zero potential. The voltage overshoots, and then draws a damping curve and converges to almost zero potential, so in reality it repeats oscillations for a certain period of time.

An inductance element 7 is inserted in series with the resonant capacitor 4 in order to reduce this vibration as early as possible and to reduce the absolute vibration amplitude as much as possible. As a result, the vibration amplitude and vibration time of the resonant current IR' become extremely small as shown in FIG. 6, and the high frequency nonlinearity on the start side of the deflection current is greatly improved.

Note that the inductance L1 of the inductance element 7 is
It needs to be sufficiently small compared to that of the deflection yoke. Further, although unnecessary pulses are generated in the resonant current generator R' and the flyback voltage A', they occur during the flyback generation period and do not affect the deflection current during the display period.

Effects of the Invention The present invention is constructed as described above, and provides the following effects. In other words, in order to make the vibration after the end of the flyback of the resonant current small and sharply converge to zero, the high-frequency nonlinearity near the start of the deflection current sweep is improved, and the high frequency nonlinearity is improved near the left end of the image on the CRTK display (the side where the horizontal sweep starts). ), the vertical pattern is eliminated and the image quality is improved.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional horizontal deflection circuit, Figures 2 and 3 are
4 is a circuit diagram of an embodiment of the present invention, and FIG. 5 is a waveform diagram of each part in FIG. 4. 2.3...Switching transistor, 4.
... Resonance capacitor, 6 ... Damper diode, 6 ... Deflection yoke, 7 ... Bin inductance element, T1 ... Transformer. Name of agent Patent attorney Toshio Nakao and 1 other person @+
Figure 2 Figure 3

Claims (1)

[Claims] An output transistor for horizontal deflection, a damper diode whose collector and cathode sides are connected to each other and whose anode side is grounded, and a resonance whose one end is connected to the collector of the output transistor and whose other end is grounded via an inductance element. Horizontal deflection circuit 0 consisting of a capacitor