JPS60242774A - Deflection distortion correcting circuit of cathode-ray tube display device - Google Patents

Abstract

PURPOSE:To correct sufficiently right and left pin cushion distortion at the entire range of a cathode ray tube raster even when a vertical blanking time is short by applying a waveform having steep rising to the vertical blanking part of an output of a sawtooth wave generating circuit, that is, a waveform of a vertical deflection output circuit to correct a voltage waveform modulating a horizontal deflection circuit. CONSTITUTION:The output voltage of a vertical deflection output circuit 8 is steep at the rise of a part where a vertical blanking period is started. The input voltage wave of a phase inverting circuit 4 is corrected by adding a proper amount of the steep part. Thus, even if the vertical blanking time in a CRT sweep is short, the pin cushion distortion at upper and lower parts of the cathode ray tube screen raster is corrected sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a left-right pincushion distortion correction circuit for a cathode ray tube display device (hereinafter abbreviated as CRT) used in a display monitor device or the like.

[Prior art]

The fluorescent surface of cathode ray tubes used in display monitor devices is not a spherical surface centered on the deflection point of the electron beam, but the distance from the deflection point to the periphery of the cathode ray tube is large, so when the electron beam is deflected, the raster ( (raster) produces pincushion-like distortion. These strains are called vertical pincushion strain and left/right pincushion strain.

FIG. 1 is a block diagram showing a conventional circuit for correcting left-right pincushion distortion. (4) is a phase inversion circuit, (5) is a multiplication circuit, (6) is a phase inversion circuit, and (7) is a horizontal deflection circuit.

Also, Figure 2 shows the voltage waveforms at each part in Figure 1.
The prisoner is a vertical saw 9 wave generation circuit (11 output voltages, (B)
is the input voltage of the phase inversion circuit (4), (C) is the output voltage of the phase inversion circuit (4), (D) is the output voltage of the multiplication circuit M (s+), and ■ is the output of the phase inversion circuit (6). It is voltage. Figure 2 (Fl.

The waveform of (Gl, (I()) will be explained in a later section.

The voltage that is applied to the CRT in the vertical direction is generated by the vertical sawtooth wave generator circuit (1), as shown in Figure 2, which is divided by the voltage dividing resistor (2).

(3) Yo! The voltage is set to an appropriate amplitude 11 as shown in FIG. 2 (B), and this waveform is inverted by the phase inversion circuit (4) to generate a voltage with the waveform shown in FIG. 2 (9). , and the voltage value is y. To simplify the explanation, y = 0 at the point 1 = 0 in Figure 2 (B), TC).
If Q, the waveform in FIG. 2(B) is expressed as yB=-at, and the waveform in FIG. 2(C) is expressed as y=at, and in the multiplier circuit (5), B, yo = -a2 t2...
・Obtain the parabolic waveform voltage in (1).The voltage shown in Figure 2 (6) is the voltage in the form of equation +11, whose phase is inverted by the amplifier in the multiplier circuit (5), and the DC level is changed before being output. The phase inversion circuit (6)
The voltage is inverted to the form shown in FIG. 6, and the output of the horizontal deflection circuit (7) is amplitude-modulated using this voltage. As a result of this amplitude modulation,
At the starting point of the CRT's vertical sweep (i.e., at the top of the raster on the cathode ray tube surface), the horizontal deflection voltage is smallest, increasing as it moves toward the center, reaching its maximum at the center, and decreasing as it moves downward from the center. CR
Since the minimum value is reached at the end point of the vertical sweep of T (ie, the bottom end of the raster on the cathode ray tube surface), it is possible to correct the left and right pincushion distortion that appears on the CRT screen.

However, the conventional circuit has the following drawbacks.

In other words, the vertical saw wave shown in Figure 1 (■) is an ideal waveform, and the time from the end point of the sweep to the start point of the next cycle's sweep is 0, but it is actually a vertical saw wave. As shown in FIG. 2F, the waveform output from the wave generation circuit 111 changes from the end point t□ of one sweep to the start point t2 of the next sweep.
It takes a certain amount of time to
Expressed as bt, the output of the multiplier circuit (5) corresponding to the portion from t0 to t2 becomes a parabolic waveform voltage of the form -b2 t2, and this occurs on both sides of the parabolic waveform voltage shown in equation (1), so the multiplier circuit (5) Parabola′ output from (5)
The voltage waveform becomes the waveform shown in FIG. 2(G).

The vertical blanking time of the CRT sweep is long, as shown in Figure 2 (
There is no problem if only the -a2t2 type parabolic waveform voltage part of the waveform shown in 6) is used, but if the vertical blanking time is short as shown in the second drawing, τ The pincushion distortion cannot be corrected during the time indicated by (that is, the upper and lower end portions of the cathode ray tube surface raster).

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and in this invention, the vertical retrace part of the output of the sawtooth wave generation circuit has a sharp rising waveform, that is,
The voltage waveform modulating the horizontal deflection circuit was corrected by adding the waveform of the vertical deflection output circuit.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram showing one embodiment of the present invention.
The same reference numerals as in the figure indicate the same or equivalent parts, (8) is a vertical deflection output circuit, (9) is a coupling capacitor, and uO is a coupling resistor. FIG. 4 is a waveform diagram showing the voltage waveform of each part in FIG. 3, where FIG. 4 (4) is the output voltage waveform of the vertical deflection output circuit (8), and FIG. The output waveform of the wave generation circuit (1), Figure 4 (C) is the phase inversion circuit (4)
FIG. 40 shows the output waveform of the phase inversion circuit (6).

As shown in FIG. 4(2), the output voltage of the vertical deflection output circuit 18) has a steep rise at the beginning of the vertical retrace period. By adding an appropriate amount of this steep portion to the waveform shown in FIG. 4(B), the input voltage waveform of the phase inversion circuit (4) is corrected as shown in FIG. 4(C). Figure 4 (The waveform shown in C1 is close to the ideal waveform shown in Figure 2 (B), and the waveform shown in Figure 2 (F') (corresponds to the waveform in Figure 4 (B))
Since the time between t□ and t2 is sufficiently shortened, even when the vertical blanking time is short in CRT sweep, pincushion distortion at the upper and lower end portions of the cathode ray tube surface raster can be sufficiently corrected. can.

〔Effect of the invention〕

As described above, according to the present invention, even when the vertical blanking time is short, left-right pincushion distortion can be sufficiently corrected over the entire range of the cathode ray tube.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the conventional 1-river route, and Figure 2 is a block diagram showing the 1st river route.
FIG. 3 is a block diagram showing an embodiment of the present invention, and FIG. 4 is a waveform diagram showing voltage waveforms at various parts in FIG. 3. (1) Vertical sawtooth generation circuit, (4) Phase inversion circuit, (5) Multiplier circuit, (7) Horizontal deflection circuit, (8) Vertical deflection output circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Oiwa Masuomon Hi・-1)-・11I4-Vertical graph/King time dew n

Claims (1)

[Claims] A parabolic waveform voltage that changes parabolically with respect to time is generated by multiplying a vertical saw short wave voltage used for vertical deflection of a cathode ray tube display device by a voltage with a waveform obtained by inverting the waveform of this voltage. , in a deflection distortion correction circuit for a cathode ray tube display device, which modulates a horizontal deflection voltage used for horizontal deflection of the cathode ray tube display device using the parabolic waveform voltage to correct left-right pincushion distortion on the display surface of the cathode ray tube display device, The output voltage of the vertical deflection output circuit of the display device is added to the vertical sawtooth voltage at a predetermined ratio to improve the rising waveform of the vertical sawtooth voltage. A deflection distortion correction circuit for a cathode ray tube display device, characterized in that the parabolic waveform voltage is generated from a wave voltage.