JPH066635A - Raster amplitude changeover circuit - Google Patents

Abstract

PURPOSE:To select a raster amplitude with a simple circuit by providing a capacitor and a switch in parallel with an S-shaped correction capacitor so as to turn on/off the switch. CONSTITUTION:A switch 16 is connected in series with a capacitor 15 and an S-shaped correction capacitor 14 is connected in parallel to the series connection and a horizontal deflection coil 13 is connected further in series with the parallel connection. Moreover, a resonance capacitor 12, a damper diode 11 and a horizontal output transistor(TR) 10 are connected in parallel with the series connection. When the switch 16 is turned on, a voltage across the S- shaped correction capacitor 14 is as shown in waveform 20 and a deflection current flowing to the horizontal deflection coil 13 is as shown in a current 21. When the switch 16 is turned off, only the S-shaped correction capacitor 14 remains and the combined capacitor is smaller than the capacitance when the switch 16 is closed, the voltage across the capacitor is as shown in waveform 22 and the deflection current is as shown in a current 23 and then the scanning quantity is increased, then raster is over-scanned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for switching a raster amplitude in a video display device such as a television and a monitor.

[0002]

2. Description of the Related Art In recent years, in a video display device such as a television and a monitor, the raster amplitude is switched by changing an amplitude control voltage input to a diode modulator circuit.

A conventional circuit will be described below. Figure 3
Shows a conventional circuit. In FIG. 3, 30 is a horizontal output transistor, 31 and 32 are damper diodes, 33 and 34 are resonance capacitors, 35 is a horizontal deflection coil, 36 is a S-correction capacitor, 37 is a bridge coil, 38 is a capacitor, and 39 is an amplitude. Control voltage.

First, in the first half of the scan when the amplitude control voltage 39 is not applied, the currents I ₁ and I are obtained by using the voltage V _A across the S-correction capacitor 36 and the voltage V _B across the capacitor 38 as power sources, respectively. ₂ flows, V _F = V _A + V _B ,
In the latter half of scanning, the sum of the counter electromotive force V _Y generated at both ends of the horizontal deflection coil 35 and the counter electromotive force V _L generated at both ends of the bridge coil 37, the magnitude of which is the current I ₁ flowing in the scanning period,
Since a current proportional to I ₂ flows, V _F = V _Y + V _L is constant.

When the amplitude control voltage 39 is applied, I ₃ flows in the first half of the scan, and the voltage of the capacitor 38 drops to V _A > V _B , but I ₁ increases and flows, and V _A increases. Therefore, V _F is constant. Scanning the second half through a damper diode 32 from ground, counter electromotive when the S-shaped capacitor 36, current flows through the horizontal output transistor 30 exits the horizontal deflection coil 35, is generated across the horizontal deflection coil 35 with increasing V _A The electric power V _Y increases, and the decrease of V _B decreases the counter electromotive force V _L generated in the bridge coil 37. Therefore, by changing the amplitude control voltage 39,
Amount of deflection current flowing in the deflection coil 35 of the horizontal deflection coil,
That is, it controls the raster amplitude.

[0006]

However, in the above-mentioned conventional configuration, the horizontal output circuit constitutes a diode modulator circuit, and a circuit for generating an amplitude control voltage must be additionally provided, so that the circuit is complicated. . The present invention solves the above-mentioned conventional problems, and an object thereof is to switch the raster amplitude with a simple circuit.

[0007]

In order to solve the above-mentioned problems, the raster amplitude switching circuit of the present invention is a resonance type horizontal output circuit using an S-shaped correction capacitor and is connected in parallel with the S-shaped correction capacitor. The circuit configuration is characterized in that the raster amplitude is switched by providing a capacitor and a switch in series and turning the switch on and off.

[0008]

According to the present invention, the raster amplitude can be switched with a simple circuit by the above-mentioned configuration.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 10 is a horizontal output transistor, 11 is a damper diode, 12 is a resonance capacitor, 13 is a horizontal deflection coil, 14 is an S-shaped correction capacitor, 15 is a capacitor, and 16 is a switch.

A switch 16 is connected in series with the capacitor 15, and an S-shaped capacitor 14 is connected in parallel with the switch 16, and a horizontal deflection coil 13 is further connected in series. Further, the resonance capacitor 12, the damper diode 11, and the horizontal output transistor 10 are further connected in parallel with it.

The operation of the raster amplitude switching circuit configured as described above will be described.

In FIG. 1, when the switch 16 is turned on, the voltage across the S-shaped correction capacitor 14 becomes as shown by 20 in FIG. 2, and the deflection current flowing through the horizontal deflection coil 13 is as shown in FIG. It looks like 21. Then switch 16
When the switch is off, the capacitor is only the S-shaped correction capacitor 14, and the total capacitance value is the switch 1
Since it is smaller than that when 6 is turned on, the voltage across it is as shown by 22 in FIG. Then, the deflection current becomes as shown by 23 in FIG. 2, and the scanning amount increases, so that the raster becomes overscan.

As described above, according to this embodiment, in the resonance type horizontal output circuit using the S-shaped correction capacitor, the capacitor and the switch are provided in parallel with the S-shaped capacitor and the switch is turned on and off. As a result, the raster amplitude can be switched with a simple circuit.

[0015]

As described above, in the resonance type horizontal output circuit using the S-shaped correction capacitor, the capacitor and the switch are provided in parallel with the S-shaped correction capacitor, and the switch is turned on / off to simplify the operation. The raster amplitude can be switched in the circuit.

[Brief description of drawings]

FIG. 1 is a raster amplitude switching circuit diagram according to an embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining the operation in FIG.

[Fig. 3] Conventional raster amplitude switching circuit diagram

[Explanation of symbols]

10 Horizontal Output Transistor 11 Damper Diode 12 Resonant Capacitor 13 Horizontal Deflection Coil 14 S-Shaped Capacitor 15 Capacitor 16 Switch 20 Voltage Waveform across S-Shaped Capacitor at Switch-on 21 Horizontal Deflection Current at Switch-on 22 At Switch-off Voltage waveform across S-capacitor of the horizontal capacitor 23 Horizontal deflection current at switch off

Claims (1)

[Claims] 1. A resonance type horizontal output circuit using an S-correction capacitor, wherein a capacitor and a switch are provided in parallel with the S-correction capacitor and the raster amplitude is switched by turning the switch on and off. Raster amplitude switching circuit characterized by.