JPS63269692A - Convergence correcting device - Google Patents

Abstract

PURPOSE:To perform highly accurate convergence correction with a simple constitution, by calculating a two-dimensional functional equation of higher degree in the form of the product of an one-dimensional function of higher degree whose variable is horizontal scanning time and another one-dimensional function of higher degree whose variable is vertical scanning time. CONSTITUTION:Each coefficient of an one-dimensional function of higher degree whose variable is horizontal scanning time and another onedimensional function of higher degree whose variable is vertical scanning time is found from the mis-convergence quantity at each setting point and the two one-dimensional functions of higher degree whose variables are horizontal and vertical scanning times are calculated by using each coefficient thus found. Then the two functions are multiplied by each other at a multiplier circuit 17 and a two-dimensional function expressing the waveform of a convergence correcting current is obtained. Then the convergence correcting current of the waveform is made to flow to a correcting coil 21. Therefore, highly accurate convergence correction can be performed with a simple constitution and even video signals of different horizontal scanning line numbers can be coped with.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a convergence correction device for color television receivers, projection type color television receivers, and the like.

[Prior Art] Figure 3 shows a convergence yoke for convergence correction of a CRT having a delta-type electron gun, (22) is a core,
Coils (21) are provided in pairs for each of R, G, and B electron beams. In order to correct the convergence, it is necessary to apply a magnetic field that superimposes a parabolically changing magnetic field in the horizontal and vertical periods, as shown in FIG. Conventionally, as a method of creating such a magnetic field,
There are so-called analog convergence correction devices in which horizontal pulses and vertical pulses are shaped into waveforms by an integrating circuit and then superimposed, and digital convergence correction devices.

FIG. 5 shows a conventional convergence device shown in, for example, Japanese Patent Laid-Open No. 61-10386, in which (31) is a test pattern generation circuit, (32) is a control panel, (31) is a test pattern generation circuit, (32) is a control panel, (
33) is a write address generation circuit, (34) is a write data generation circuit, (35) is a read address generation circuit, (
(36) is a multiplexer, (3,7) is a write/read control circuit, (38) is a field memory, (38) is a horizontal extrapolation circuit, (40) is a line memory, (41) is a vertical extrapolation circuit, ( 42) is a vertical interpolation calculation circuit, (43) is D
/A conversion circuit, (44) is a low-pass filter (LP
F), (20) is an output circuit, and (21) is a correction coil shown in FIG.

This digital convergence correction device, for example, as shown in FIG.
Adjust the amount of misconvergence at the 5X5=25 set points P1 to P25 set above using the keyboard of the control panel (32) in Fig. 5, and store the correction data in the field memory (38). The field memory (38) is stored in response to scanning on the display surface (50).
), and the correction amount for the parts other than the set points P1 to F25 is corrected for each scanning line from the correction data in the vertical direction in the vertical direction (vertical direction) using the vertical interpolation calculation circuit (42). Calculate and interpolate the value, and the horizontal direction is D/
After converting to an analog waveform in the A conversion circuit (43), the L
A correction magnetic field was obtained by interpolating with P F (44) and passing a correction current having the same waveform as the magnetic field shown in FIG. 4 through the correction coil (21).

[Problems to be Solved by the Invention] As mentioned above, in the conventional convergence correction device, the analog system can perform correction using a relatively simple circuit, but there is a problem in that the correction accuracy is low, and the digital system has the problem that the correction accuracy is low. However, the circuit configuration is complicated, and between vertical adjustment points, correction values are calculated and interpolated for each scanning line from adjacent vertical correction data, so images with different numbers of horizontal scanning lines are There was a problem in that it could not be corrected when the signal was received.

This invention was made to solve the above-mentioned problems, and aims to provide a convergence correction device that has a relatively simple configuration, has high correction accuracy, and can handle video signals with different numbers of horizontal scanning lines. The purpose is

[Means for Solving the Problems] The convergence correction device according to the present invention uses a binary height that uses a horizontal scanning time and a vertical scanning time as variables to represent a correction current waveform that is applied to a correction coil in order to correct misconvergence. The present invention is characterized in that the next function is obtained by calculating the product of a one-dimensional higher-order function with the horizontal scanning time as a variable and a one-dimensional higher-order function with the vertical scanning time as a variable.

[Operation] In this invention, each coefficient of a one-dimensional high-order function with the horizontal scanning time as a variable and a one-dimensional high-order function with the vertical scanning time as a variable is determined from the amount of misconvergence at each set point, and each of these coefficients is calculated. Then, these two one-dimensional high-order functions are multiplied to obtain a two-dimensional high-order function representing the convergence correction current waveform, which is then applied to the correction coil. A convergence correction current of this waveform is applied.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1st
The figure shows the set point P+-'P9 set as shown in Figure 2.
This is a convergence correction device for obtaining an approximate correction waveform expressed by a two-dimensional quadratic function equation shown in equation (1) below from the convergence correction amounts a1 to a9.

f(th, tv)=(α1+α2th+α3th2)(
β1+β2tma+β3tv”) ... (1) Where, th: Horizontal scanning time during which the electron beam passes through each set point P1 to P9 tv: Vertical scanning time during which the electron beam passes through each set point P1 to P9 Two-dimensional quadratic function In order to represent all waveforms, the following equation (2) is required, but to correct general convergence, the correction waveform represented by the above equation (1) is sufficient.

f (th, tv) = (k++ to 2・th+ to 3・th2
)+(k4+5・th+6・th2)tv+(
k7+ke・th+kg4b2)・tv2・
・-(2) The coefficients 1 to 9 in equation (2) can be obtained by the calculations described later, and the coefficients α1 to α3 and β1 to β3 in equation (1) can be calculated from the coefficients 1 to 9, as follows. You can find it like this.

Equation (1) is transformed into equation (3).

f(th, tv)=(al α1+β1 α2・th+
β1 α3・Th2)+(β2 α1+β2 α2・
th+ β2 α3-Th2)・tv +(β3 α1+β3 α2・th+ β3 α3・T
h2) °tv2
(3) In order for equation (2) to be factorized into equation (1), each term in equation (2) and equation (3) must be equal. Further, the misconvergence amount a1 at the set point P1 (th=0.tmer0) is generally not zero. That is, kl
=a1 =α1β1≠0, and α1 =1. β1=
1, α2. α3. β2. When determining β3, f
(th, tv) = (1+ to 2/+-th+ to 3/+
・Th2) (4 to kl+-7・Tv2 to tv+)
...(4) Also, assuming αI 2kl and β1=1, α2.

b3. To find β2 and β3, f(th, tv) = (kl + 2 th+ 3・Th
2) (1+ to 4/to + t maju to? /kl・tv2
)...(5). That is, equation (4), (5)
The equation is an approximation of equation (2).

Since equations (4) and (5) are the same equation, the following equation (4)
The case where it is expressed by a formula will be explained.

In the figure, (1) calculates 9 to the coefficient kl - of equation (2) from the convergence correction amounts a1 to a9 of each set point P1 to P9, and then calculates 9 to 2/.

k: An arithmetic circuit that calculates + for +/; this arithmetic circuit (
1) may be included in the convergence correction device or may utilize an external arithmetic circuit. (2) is 1 for k2/ out of the numerical value l and the coefficient calculated above.

k3/ is a digital memory that stores + + kx + β4 * kl, (3) is a digital memory (2
D/A converter that converts the output of ) into an analog value, (4)
.

(5), (8), and (7) are differential amplifier circuits for multiplying the horizontal and vertical sawtooth waves and parabolic waves by the coefficients. (10) is a horizontal sawtooth wave generation circuit, (11) is a vertical sawtooth wave generation circuit, (12),
(13) is an adder circuit, (15) , (lfl),
(17) is a multiplication circuit, (20) is an output circuit, horizontal,
Vertical sawtooth wave generation circuit (10).

(11), addition circuits (12), (13), and multiplication circuits (15).

(1e) and (17) constitute a function generation circuit (60), and this function generation circuit (80) has 1 circuit, for example, in the case of a delta type CRT, 81 R, G, B, and BL circuits, a total of 4 circuits.
circuit is required.

In the above configuration, the memory (2) is not limited to a digital memory, but may be a variable resistor that provides a voltage corresponding to each coefficient, for example.

Next, the operation of this embodiment will be explained.

In FIG. 2, CR
The time taken by the electron beam of T to pass through is th=0, tv=o, and the time taken to pass through set point P5 where the correction amount is β5 is th=Th.
/2, tv=Tv/2, and the time to pass through the set point P9 where the correction amount is β9 is th=TT, tv=Tv. From equation (2), f (0, O) = a1 f (Th/ 2, O) = azf (Th,
0) = β3 f (0, Tv/2) = a4 f (Th/2, Tv/2) = asf (
Th, 'rv/2) = a6f (0, Tv)
= a7 f (Th/2, Tv) = aaf (Th
, Tv)=ag hold true. Based on these equations, the calculation circuit (1) calculates coefficients 1 to 4 and 7 using the following equations, and further calculates k 2 / k t * k 3 /
Calculate k t .

k1=a1 -2aB +ag) Digital memory (2) contains numerical value 1 and arithmetic circuit (1)
To the coefficient calculated by 2/ + + k3/ + +
4 to kl +. 7 is stored as digital data.

These data are read out as soon as the display device, such as a CRT, is powered on, and the same data is always read out during operation. These data are converted into analog voltages by a D/A converter (3). On the other hand, the linear function waveform of th obtained from the horizontal sawtooth wave generation circuit (10) inputting the horizontal pulse H and the coefficient 2/kl are input to the differential amplifier (4), and 2/kl is input to the differential amplifier (4).・Obtain th. In addition, the output of the horizontal sawtooth wave generation circuit (10) is input to the multiplication circuit (15), and
Obtain the following curved waveform (parabolic waveform) th2. This 2
The next silver waveform th2 and the coefficient 3/+ are input to the differential amplifier circuit (6) to obtain an output of 3/1·th2. Furthermore, the numerical value l and the output of the differential amplifier (4) are 2/1.
th and the output of the differential amplifier (5): +/to +・th2
By adding these in the adder circuit (12), the output (1+k2/+-th+ is 31k1・th2).
). Similarly, the output tv of the vertical sawtooth wave generation circuit (11), which inputs the vertical pulse V, and the coefficient 4 are input to the differential amplifier circuit (5) to obtain 4·tv, and multiplication is performed. The quadratic silver waveform tv2 obtained from circuit (16) and the coefficient 7
is input to the differential amplifier circuit (7) to obtain 7・tv2,
The coefficient kl, k4・tv, and k7・tv2 are added in the adder circuit (13) (7t for IH+ + tv+)
v2) is obtained. In addition, the output (1+ to 2/1・tk"
k3 /krth2) and output (4tv+ to k+
1k7tv2) in the multiplier circuit (17), (1+ to 2/th+3/krth2) X(k
1+' to +・tvCk7tv2) two-dimensional quadratic function waveform f
(th, tv) is obtained.

The output circuit (20) outputs this binary signal to the correction coil (21).
This is a circuit for flowing a convergence correction current waveform expressed by the following function.

In addition, in the above embodiment, the nine set points P shown in FIG.
The case where the approximate correction waveform expressed by the two-dimensional quadratic function equation of equation (4) is obtained from the correction amounts of 1 to P9 has been explained.
Furthermore, from the amount of correction at multiple points, for example, the amount of correction at m points in the horizontal direction and n points in the vertical direction, the total amount of Xn points, the following (6)
Find the coefficients kll~kmn of the equation, f (th, tv) = (2 for k41+ 31t for lth+
h2 +・” + + Hthll-1) + (k12 +
to 22 th+ to 32 th2+-+km2 thll
-' ) ・tv+(k+3+ to 23th+ to 33th
2+...+km3thl-1)・tv2+(k+n+
to 2n-th+ to 3nth2+ −+kmnth'l−
1)-jyn-1...(6) As the approximate expression of equation (8) is expressed by equation (7) below, f(
th, tv) = (cx l+a 2 th+α3 th
2+ -a mth'-1) (β 1+β2tma+β3
tv2+...10βntvni)...(7) By expressing the coefficients α1 to αm and β1 to βn as coefficients kll to kmn, it is possible to perform correction with higher precision than in the embodiments described above.

As can be seen by comparing equations (8) and (7) above, even when the set point is mXn, according to the present invention, each of (m + n) memories and D/A
Since only a conversion circuit, (m+n-2) differential amplifier circuits, and one multiplication circuit are required, the configuration is simplified. (However, regarding the circuit that generates the horizontal and vertical high-order fundamental waveforms of th-th"-+1 tma to tvn-1,
It's exactly the same. ) Also, in the embodiment shown in FIG. 1, the case of formula (4) is explained, but formula (4) can also be transformed into the following form. That is, f(th, tv) = (k++ to 2th+ to 3th2
) (4tv+ for k++: 7tv2 for), and 5 memories and D/A transformation circuits are required each. The coefficient of 1 in 17 can be adjusted by adjusting the gain of the output circuit (20). The same corrected waveform as in the embodiment shown in FIG. 1 can be obtained.

[Effects of the Invention] As described above, the present invention has a current waveform expressed by a two-dimensional high-order function whose variables are the horizontal scanning time and the vertical scanning time for energizing the correction coil in order to correct misconvergence. Since the configuration is configured to calculate in the form of the product of a one-dimensional high-order function with the horizontal scanning time as a variable and a one-dimensional high-dimensional function with the vertical scanning time as a variable, the configuration is simple and relatively accurate correction can be performed. This has the effect of providing a convergence correction device that can be used.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing the configuration of a convergence correction device according to an embodiment of the present invention, FIG. 2 is a diagram showing the arrangement of setting points set on the display surface of a color cathode ray tube in this embodiment, and FIG. Figure 4 is a front view of the convergence yoke, Figure 4 is a waveform diagram of the correction magnetic field generated by the convergence yoke, Figure 5 is a block circuit diagram showing the configuration of a conventional digital convergence correction device, and Figure 6 is the conventional digital convergence correction device. FIG. 3 is a front view showing an example of arrangement of adjustment points. (1)...Arithmetic circuit, (2)...Digital memory, (3)...D/A conversion circuit, (4), (5)
, (6). (7)...Differential amplifier circuit, (10)...Horizontal sawtooth wave generation circuit, (11)...Vertical sawtooth wave generation circuit, (
12), (13)...addition circuit, (15),
(1B), (17)...multiplication circuit, (20)...
- Output circuit, (60)...Function generation circuit. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) The correction current waveform necessary to correct misconvergence at multiple set points set on the display surface of a color cathode ray tube is determined by the horizontal scanning time and vertical scanning time during which the electron beam passes through each of the above set points as variables. Calculate the coefficient of each term of the approximation formula of the two-dimensional high-order function from the amount of misconvergence at each set point, and correct the misconvergence by applying a correction current having a waveform of the approximation formula to the correction coil. The convergence correction device includes means for calculating the two-dimensional high-order function equation in the form of a product of a one-dimensional high-order function with the horizontal scanning time as a variable and a one-dimensional high-order function with the vertical scanning time as a variable. Features a convergence correction device.