JPH0126234B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for correcting convergence in a color television receiver, which allows accurate adjustment, and
It is an object of the present invention to provide a digital convergence device with less convergence shift even in the periphery of a screen.

As is well known, the shadow mask type color picture tube used in general color television receivers has three electron guns: red, green, and blue. However, it is structurally impossible to arrange all of these multiple electron guns on the central axis of the color picture tube, so they are mounted slightly away from the central axis and slightly tilted inward with respect to the central axis. Therefore, on the screen on this central axis, each electron beam converges at the shadow mask, and simultaneously emit red, green, and blue fluorescent dots through the same hole, resulting in a convergence state. However, since the radius of curvature of the shadow mask is larger than the distance from the center of deflection to the center of the shadow mask, the three electron beams converge in front of the shadow mask at locations other than the central axis of the cathode ray tube. The beams cannot pass through the same hole at the same time, and the reproduced image has more color shift, or convergence shift, as it moves away from the center of the screen. In order to prevent such problems, it is necessary to perform convergence correction over the entire screen so that the three electron beams converge at the shadow mask.

Generally, passive elements such as LCR are used to generate
A method of obtaining a convergence correction waveform in an analog manner has been adopted, but there is a problem in terms of convergence accuracy. As a method of performing convergence with higher precision over the entire screen, a method of digitally performing convergence correction has been proposed, as shown in US Pat. No. 3,943,279, for example.

In the conventional example described above, the concept is to project a convergence correction pattern such as dots on the screen, digitally write the convergence correction amount data for each point in one frame memory, and read out this information. , performs D/A conversion and convergence correction. A more detailed explanation will be given below based on FIGS. 1 and 2.

First, as shown in Fig. 2, dots corresponding to the convergence adjustment points in, for example, 13 rows in the vertical direction and 9 columns in the horizontal direction are projected on the screen by the dot generator 17, and the dots are adjusted using the cursor keys 1a on the control panel 1. Select the dot corresponding to the adjustment point.
The address of the adjustment point selected with the cursor key 1a is stored in the cursor counter 14. Next, if the color to be corrected is red, for example, red is specified using the red data write key 1b on the control panel 1, and the desired data is set in the data reversible counter 2. Then, the output of the data reversible counter 2 is written to the address specified by the cursor counter 14 of the one frame memory 3. Here, the data reversible counter 2 has a cursor counter 1.
The contents of the one frame memory 3 selected in step 4 have been read out, and if you want to increase the convergence correction amount at that adjustment point, use the data reversible counter 2.
When it is desired to increase or decrease the data, the data reversible counter 2 is decremented and the desired correction amount is written to a predetermined address in the one-frame memory 3, thereby performing write correction. The same procedure is repeated for all adjustment points on the screen.

Next, reading out the convergence correction amount written in the one-frame memory 3 will be explained. Since the one-frame memory 3 stores only the correction amount for the location corresponding to each dot, it is necessary to perform interpolation for each scanning line between dots in the vertical direction. Therefore, for example, the correction amount for the first column of dots is read out from the one-frame memory 3,
After setting it in the 1H register 4, the correction amount of the second column dot is read out from the 1 frame memory 3.
The first frame read from the one-frame memory 3 in this way
Using the correction amounts in the example and second columns, the correction amount in the scanning line included between the dots in the first and second columns is determined by interpolation. That is, the difference between the correction amount in the first column and the correction amount in the second column is obtained by the subtraction circuit 5, and multiplied by the weighting coefficient for each scanning line, which is written in advance in the coefficient ROM 7, by the multiplication circuit 6. , the result and the correction amount in the second column are added together in an adding circuit 8 to perform interpolation. Furthermore, the output signal of this adder circuit 8 is converted into an analog quantity by a D/A converter 9, smoothed by a low pass filter (LPF) 10, and after being amplified, is supplied to a convergence yoke. The same applies to the other green, blue radials, and blue laterals.

According to the conventional device described above, the amount of convergence correction corresponding to the position of a dot in the screen of a color picture tube can be determined correctly, but the amount of convergence correction at a position further outside than the outermost dot can be calculated correctly. Since it is not stored in one frame memory, the amount of convergence deviation becomes large.

Therefore, the present invention provides a digital convergence device that can reduce the amount of convergence deviation in the periphery and obtain highly accurate convergence over the entire screen. An embodiment of the present invention will be described in detail below based on the drawings.

FIG. 3 shows a conceptual diagram of an embodiment of a digital convergence device according to the present invention. In FIG. 3, reference numeral 21 denotes a video signal input terminal, at which the incoming video signal is amplified to a necessary amplitude by a video circuit 22, and the color picture tube is driven. This video circuit 22 operates in the same way as a normal receiver, but is supplied with dot or crosshatch signals created by a digital convergence circuit 27, and displays them during convergence adjustment. 25 is a deflection circuit, and 29 is a deflection yoke, which deflects the electron beam of the color picture tube 23 in response to a synchronization signal arriving at the synchronization signal input terminal of 24. Reference numeral 26 denotes a control panel which is provided with keys necessary for convergence adjustment, such as a cursor key 34 for instructing which position on the screen to perform convergence correction, and a key 35 for writing data into the digital convergence circuit 27. The digital convergence circuit 27 includes a one-frame memory composed of non-volatile memory, stores the dot convergence correction amount corresponding to each adjustment point specified on the control panel 26, reads out this correction amount, and outputs it to the output circuit 28. A correction current is passed through the current amplification convergence coil 30 to correct convergence. Note that since the digital convergence circuit 27 needs to operate in synchronization with the deflection, a synchronization signal is supplied thereto.

FIG. 4 shows a block diagram of the main parts of the control panel and the 26-digital convergence circuit 27.
Components corresponding to those in FIG. 1 are indicated by the same numbers. For ease of understanding, the convergence of a picture receiver using a color picture tube with a delta type electron gun arrangement will be described below. Furthermore, the number of dots or crosshatches for convergence adjustment is 13 vertical rows and 9 horizontal columns on the screen, as shown in FIG.

First, as shown in Figure 2, dot generator 1 is displayed on the screen.
Project the dot created in step 7 and use a magnet or the like to perform static adjustment at the center point in Figure 2. Furthermore, the necessary correction current waveforms are parabolic waveforms, both horizontal and vertical, as is well known, and the configuration and operation for digitally forming them will be described below.

The one-frame memory 37 of this embodiment has a memory capacity larger than the capacity corresponding to 13 rows and 9 columns. That is, at least (13+2) rows vertically and (9
+2) It has a memory capacity corresponding to each column, and the data in the area where the memory capacity increases is calculated by extrapolation from the memory corresponding to 13 vertical rows and 9 horizontal columns.

The operation of writing the convergence correction amount of the portion corresponding to 13 vertical rows and 9 horizontal columns of the 1-frame memory 37 into the 1-frame memory is completely the same as that of the conventional example, but will be briefly explained below using FIG. 4.

Using the cursor keys 34 provided on the control panel 26, select which position of the convergence correction amount of the dot displayed on the screen is to be written to the 1-frame memory 37 as shown in FIG. 2, and at the same time select the color using the write key 35. conduct. Cursor key 3
The address of the dot selected in step 4 on the 1-frame memory 37 is stored in the cursor counter 14, and the output signal of the cursor counter 14 is added to the 1-frame memory 37 via the address multiplexer 19. 1 frame memory 37 is read out and set in the data reversible counter 2. When it is desired to increase the convergence correction amount, the data reversible counter 2 is increased, and when it is desired to be decreased, the data reversible counter 2 is decreased, and this output signal is sent to the data multiplexer 20.
The data is sequentially written into the one frame memory 37 via the . This operation is stopped when the necessary convergence correction amount is obtained. The operation explained above is performed by red radial,
Repeat for all dots displayed in Figure 2: green radial, blue lateral, and blue radial.

As described above, the convergence correction amounts for all the dots displayed in FIG. 2 have been written into the one-frame memory 37. Next, the second
A method of obtaining the convergence correction amount outside the dots displayed in the figure by extrapolation from the correction amount written in the one-frame memory 37, and writing the correction amount obtained by this extrapolation into the one-frame memory 37. Let's talk about. FIG. 5a schematically shows how the convergence correction amount of, for example, the red radial is written into the one frame memory 37. The convergence correction amount is expressed as An.m, where n is the horizontal The direction address is the vertical address, and m is the vertical address. The convergence correction amount of the dots shown in Figure 2 is as shown in Figure 5a.
It is written in the part that is not shaded.

_For vertical _{extrapolation , for example ,} as _shown in _{FIG . .0} ~
A _13.0 is calculated and stored in ₁ frame memory 37
This is done by writing to a predetermined address. Similarly, correction amounts _A1.8 to _A13.8 and _A1.9 to _A13.9 are sequentially read from _the one-frame memory ₃₇ , and _the correction _{amounts A1} .
₁₀ to _A13.10 are calculated and written into _the one frame memory 37, and the vertical extrapolation is completed. The specific configuration and operation for performing the above-mentioned vertical extrapolation are shown in FIG.
The output signal is added to the one-frame memory 37 via the address multiplexer 19, and the convergence correction amount _A1.2 in the one-frame memory ₃₇ is read out and set in the register 31, after which the extrapolation address counter 18 is changed Then, the correction amount A _1.1 is read out from the one frame memory ₃₇ . In the case of linear extrapolation, the subtraction circuit 32 subtracts _A1.2 from the correction amount _A1.1 read from the one-frame memory 37, and then the addition circuit ₃₃ adds _the original _A1.1 to the output signal of the subtraction circuit ₃₂ .
The extrapolated value _of the correction _amount A _1.0 (=A _{1.1 −A 1.2} + _{A 1.1}
= 2A ₁ . ₁ − A ₁ . ₂ ). Next, the extrapolation address counter 18 is changed, and _{the correction amount A 1.0 obtained} as described above is written into the one-frame memory 37 via the data multiplexer 20. Similarly, _{the correction amounts A 1.10 to A 13.10 are calculated and} written into the one-frame memory 37.

_{For extrapolation} in _the horizontal _{direction ,} as _{shown in FIG . 0} ~ _A0 .
₁₀ by extrapolation, and then the correction amount A ₁₂ . ₀ ~ A ₁₂ . ₀
and A _13.0 to _{A 13.10} may be read out in order from the one-frame memory 37 _and the correction amounts A _14.0 to _{A 14.10} may be obtained by extrapolation _. In the case of linear extrapolation, the extrapolated value is obtained using the register 31, the subtraction circuit 32, and the addition circuit 33, similarly to the vertical extrapolation. Then, the output signal of the extrapolation address counter 18 is sent to the one frame memory 37 via the address multiplexer 19.
In addition, the extrapolated value obtained above is added to the one-frame memory 37 via the data multiplexer 20, and the extrapolated value is written to a predetermined address, thereby completing the horizontal extrapolation.

As mentioned above, extrapolation in the vertical and horizontal directions is not done by linear extrapolation, but by assuming the same amount as the convergence correction amount at the outermost convergence adjustment point in Figure 2.
By writing to the frame memory, it is possible to easily reduce the amount of convergence shift around the screen. The extrapolation operation described above is performed for all of the red radial, green radial, blue lateral, and blue radial.

The operation of reading out the convergence correction amount written in the one-frame memory 37 as described above is the same as the operation of the conventional device, so a brief explanation will be given here. Since the 1-frame memory 37 stores only the correction amounts for the locations corresponding to the dots in FIG. There is a need to do. Therefore, for example, the amount of correction for the dots in the first column is read out from the one frame memory 37 and set in the 1H register 4, and then the amount of correction for the dots in the second row is read out from the one frame memory 37. Using the correction amounts of the first and second columns read out from the one-frame memory 37 in this way, the correction amount of the scanning line included between the dots of the first and second columns is determined by interpolation. That is, the difference between the amount of correction in the first column and the amount of correction in the second row is determined by the subtraction circuit 5, and the weighting coefficient for each scanning line written in advance in the coefficient ROM 7 is multiplied by the multiplication circuit 6. Addition circuit 8 adds the result and the correction amount on the second line.
Add and interpolate. Next, the output of the adder circuit 8 is converted into an analog value by the D/A converter 9, smoothed by a low-pass 10 filter (LPF), amplified, and then supplied to the convergence yoke. 1 frame memory 3
Reading from 7 is performed for all of the red radial, green radial, blue lateral, and blue radial.

Note that a synchronizing signal is applied to the input terminal 36 in FIG. 4, and the control circuit 12 operates the read address counter 16 and the extrapolation address counter 18.

As shown in Fig. 2, the dots displayed on the screen are selected using the cursor keys 34, and when the output signal of the cursor counter 14 and the output signal of the read address counter 16 are added to the comparator 15 and they match, a match is detected. creating a signal. This coincidence signal is applied to the dot generator 15, and the position of the selected dot can be monitored by blinking the dot selected by the cursor key 34 or by performing brightness modulation.

As is clear from the above, the digital convergence device of the present invention is equipped with a one-frame memory having a capacity larger than the memory capacity corresponding to the convergence adjustment point displayed on the screen, By extrapolating the amount of convergence correction further outside the adjustment point and writing that value into this one-frame memory, the amount of convergence correction at the periphery of the screen can be reduced and the amount of convergence correction can be applied to the entire screen. In addition to achieving highly accurate convergence, the correction amount for the peripheral area of the screen is automatically calculated by simply adjusting the convergence correction point displayed on the screen, reducing adjustment time. is measured.

Regarding smoothing of the correction amount in the horizontal direction, if there is a sudden change in the correction amount between adjustment points, especially in the periphery of the screen where the correction amount increases, it is necessary to use a low-pass filter or convergence filter for smoothing the horizontal direction. The transient characteristics of the output circuit that drives the yoke may affect the surrounding adjustment points, but in the present invention, the convergence around the screen can be adjusted by using extrapolation to find the correction amount for points that are not displayed on the screen. Improved accuracy and lower power consumption of the output circuit can be achieved. Furthermore, since there is no sudden change in the amount of correction between adjustment points around the screen, convergence correction at the periphery of the screen can be achieved with high accuracy with a small number of adjustments, which has a great practical effect.

In this explanation, we have described color picture tubes with a delta-type electron gun arrangement, but color picture tubes with an in-line electron gun arrangement, and projection picture tubes that use multiple projection-type picture tubes to construct a large-screen TV. It goes without saying that the idea of the present invention is also effective in a type television receiver.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a conventional digital convergence device, FIG. 2 is a front view of a picture tube showing the projected state of convergence adjustment dots, and FIG. 3 is a configuration diagram showing an embodiment of the digital convergence device of the present invention. , FIG. 4 is a configuration diagram of the main parts of this embodiment, and FIG.
The figure is a schematic diagram for explaining the extrapolation method of this embodiment. 2... Reversible counter for data, 4... 1H register, 5... Subtraction circuit, 6... Multiplication circuit, 7...
Coefficient ROM, 8...addition circuit, 9...D/A converter, 10...LPF, 12...control circuit, 14...
...Cursor counter, 15...Comparator, 16...
Read address counter, 17... Dot generator, 18... Extrapolation address counter, 19...
...Address multiplexer, 20...Data multiplexer, 26...Control panel,
27...Digital convergence circuit, 28...
...Output circuit, 30...Convergence coil, 3
1...Register, 32...Subtraction circuit, 33...Addition circuit, 37...1 frame memory.

Claims (1)

[Scope of Claims] 1. Means for selecting an adjustment point displayed on a screen, means for writing a convergence correction amount for each of the adjustment points into a one-frame memory, and convergence correction for the adjustment point from the one-frame memory. means for reading out the amount of convergence correction at a point outside each of the adjustment points and not displayed on the screen by extrapolation from the amount of convergence correction at each of the adjustment points; means for writing convergence correction amounts for points not displayed on the screen in the one-frame memory; driving means for reading out the one-frame memory using a clock signal synchronized with horizontal deflection and vertical deflection; A digital convergence device comprising means for converting the output value into an analog value and applying it to a convergence yoke. 2. A patent claim characterized in that the convergence correction amount for a point that is outside the adjustment point and is not displayed on the screen is set to the same value as the correction amount for the outermost adjustment point of the adjustment point group. The digital convergence device according to scope 1.