JPH04215388A - Vertical linearity correction circuit - Google Patents

Abstract

PURPOSE:To offer a correction method without changing vertical screen size by vertical linearity correction quantity especially. CONSTITUTION:A current value that flows on a capacitor 14 for oscillation can be corrected without changing the amplitude of an oscillation saw-tooth wave voltage by passing a saw-tooth wave deflecting output voltage generated at a feedback resistor 11 through a capacitor 13 which blocks a DC component that flows in from the constant current circuit of a saw-tooth wave generation circuit 1, and feeding it back to the control terminal 8 of the saw-tooth wave generation circuit 1. Especially, the matching adjustment of vertical linearity and the vertical screen size that is a problem when plural vertical reflecting frequencies exist can be performed individually by this invention. therefore, adjusting time can be shortened, and an effect to reduce dispersion due to the adjustment can be obtained.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to vertical deflection circuits for CRT displays, etc., and is a vertical linearity correction circuit in which the amplitude of the oscillating sawtooth voltage does not change due to the correction value of the vertical linearity correction circuit, and the vertical screen size does not change. Regarding.

0002

[Prior Art] A vertical linearity correction circuit corrects a sawtooth wave deflection output voltage in an S-shape over time.
It consists of a vertical correction circuit that corrects the oscillating sawtooth wave voltage so that it is small at the beginning and becomes large at the end.

The vertical correction circuit feeds back the sawtooth wave deflection output voltage to the control terminal of the constant current circuit of the sawtooth wave generation circuit, and corrects the alternating current value flowing through the constant current circuit. Since the vertical correction circuit is made up of an element that passes a DC component, the DC current value of the constant current circuit changes depending on the correction value of the vertical correction circuit. As a result, the amplitude of the oscillating sawtooth voltage changes, and the vertical screen size also changes.

[0004] From the above, there is a problem that vertical linearity adjustment and vertical screen size adjustment are trade-off adjustments, making the adjustment complicated and time-consuming, and increasing the variation due to adjustment.

Note that related to this type of vertical linearity correction circuit, for example, Japanese Patent Laid-Open No. 63-254866
Publication No. 1 is mentioned.

[0006]

[Problem to be solved by the invention] In the prior art,
The amplitude of the oscillating sawtooth voltage changes depending on the correction value of the vertical correction circuit for vertical linearity correction, and the vertical screen size changes, so vertical linearity adjustment and vertical screen size adjustment become trade-off adjustments, making the adjustment complex and time-consuming.
There was a problem that variations due to adjustment became large.

An object of the present invention is to solve the problems of the prior art described above.

[0008]

[Means for Solving the Problems] In order to achieve the above object, in the present invention, a sawtooth wave deflection output voltage is fed back to a control terminal of a constant current circuit of a sawtooth wave generation circuit, and an alternating current flowing through the constant current circuit is provided. In the circuit that corrects the current value,
Add a new element to block DC components.

[0009]

[Operation] By adding an element that blocks the DC component to the circuit that corrects the alternating current value flowing through the constant current circuit of the sawtooth wave generation circuit, the oscillating sawtooth voltage can be adjusted by the correction value of the vertical correction circuit. Since the amplitude does not change,
Vertical linearity adjustment does not change the vertical screen size.

0010

Embodiment FIG. 1 shows a basic embodiment of the present invention.

The broken line section 1 is a sawtooth wave generation circuit,
An oscillating sawtooth voltage is extracted as an oscillation output by causing a constant current to flow through the oscillation capacitor 14 by the function of a constant current transistor 6, which is the main component of the constant current circuit, and the control terminal 7 of the constant current transistor 6 ,8
By controlling the voltage applied to the oscillation capacitor 14, the current value flowing through the oscillation capacitor 14 is corrected. The oscillating sawtooth voltage thus extracted is supplied to the vertical amplification/output circuit 2 at the next stage.

The broken line section 3 is a negative feedback circuit, which includes vertical amplification,
Vertical amplification is applied so that the sawtooth wave deflection output current waveform, which is the output of the output circuit 2, has a waveform similar to the oscillating sawtooth voltage, and negative feedback is applied to the output circuit 2 to ensure stable vertical deflection operation. There is. In addition, vertical amplification and output circuit 2
A vertical deflection coil 9 is connected to the vertical output coupling capacitor 10 and a feedback resistor 11 to convert the sawtooth wave deflection output current into a sawtooth wave deflection output voltage.
is supplied to.

The parabolic wave generating circuit 4 is a circuit that generates a parabolic wave voltage waveform from the sawtooth wave deflection output current. The parabolic voltage waveform is generated by the sawtooth wave generation circuit 1.
S-shaped correction of vertical linearity is performed by correcting the oscillating sawtooth voltage waveform into an S-shaped one.

The above is the overall configuration and operating principle of the vertical deflection circuit.

The vertical linearity vertical correction circuit, which is the main part of the present invention, will be described below. The broken line portion 5 is a vertical linearity correction circuit. By causing the sawtooth wave deflection output current flowing through the vertical deflection coil 9 to flow through the feedback resistor 11, a sawtooth wave deflection output voltage similar to the sawtooth wave output current is generated in the feedback resistor 11. A part of the sawtooth wave deflection output voltage is fed back to the control terminal 8 of the sawtooth wave generation circuit 1 after passing through a capacitor 13 for blocking the DC component flowing from the constant current circuit of the sawtooth wave generation circuit 1. Therefore, the current value flowing through the oscillation capacitor 14 can be corrected to be small at the beginning of the vertical scan and large at the end of the vertical scan without changing the amplitude of the oscillating sawtooth voltage. As a result, the vertical linearity can be vertically corrected so that the oscillating sawtooth wave voltage is equalized at the top and bottom of the screen without changing the vertical screen size.

As described above, since the amplitude of the oscillating sawtooth voltage does not change depending on the amount of vertical linearity correction, the vertical screen size does not change depending on the amount of vertical linearity correction. Therefore, vertical linearity and vertical screen size can be adjusted individually, rather than being adjusted in a balanced way.

[0017]

According to the present invention, the vertical screen size does not change due to the correction value of the vertical linearity vertical correction circuit, which has conventionally been a problem especially when there are a plurality of vertical deflection frequencies. Vertical linearity adjustment and vertical screen size adjustment can be adjusted individually rather than as a combined adjustment. Therefore, adjustment time can be shortened,
This has the effect of reducing variations due to adjustment.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a basic embodiment of the present invention.

[Explanation of symbols]

1. Sawtooth wave generation circuit 5. Vertical linearity up and down correction circuit 6. Constant current transistor 8. control terminal 11. feedback resistance 13. Capacitor to block DC component 14. Oscillation capacitor

Claims (1)

[Claims] Claim 1: A vertical deflection circuit consisting of a sawtooth wave generation circuit, a negative feedback amplifier circuit, and an amplification output circuit, including an oscillation capacitor, a constant current circuit for flowing current to the oscillation capacitor, and a current of the constant current circuit. a sawtooth wave generation circuit that generates an oscillating sawtooth voltage in the oscillation capacitor by drawing current from the oscillation capacitor through the constant current circuit; By feeding back an output voltage similar to the wave deflection output current to the control terminal of the constant current circuit, the current value flowing through the oscillation capacitor is reduced at the beginning of the oscillating sawtooth wave voltage and increased at the end. A vertical linearity correction circuit characterized in that the linearity correction circuit is provided with an element for blocking a direct current component in order to prevent the direct current value of the constant current circuit from changing due to the correction value of the vertical linearity correction circuit. .