JPS6112191A - Digital convergence device - Google Patents

Abstract

PURPOSE:To execute the convergence correction by detecting a deflecting current so as to detect an absolute position on a screen, matching an address of digital memory to the absolue value and writing and reading a convergence correction amount. CONSTITUTION:A signal SV in proportion to a deflecting current IV for flowing in a vertical main deflecting coil of a cathode ray tube among projection-type cathode ray tubes 13-15 and a signal SH in proportion to a deflecting current IH for flowing in a horizontal main deflecting coil are supplied to terminals 30 and 31. Since a beam spot position on a screen is decided by the currents IV and IH, data for showing an absolue position on a screen 16 is obtained from the signals SV and SH in proportion to the currents IV and IH, respectively. Moreover, addresses of a digital memory 21 are set in correspondence to plural prescribed positions on the screen 16, and data of the prescribed convergence correction amount corresponding to the position on the screen 16 is stored.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital convergence device that corrects the convergence of a color television receiver by digital processing.

[Conventional technology]

Generally, in a normal color television receiver using a cathode ray tube (CRT), red is displayed on the fluorescent surface.

The three primary colors green and blue are combined to create a color image. In addition, in a projection type color television receiver equipped with a projection type cathode ray tube (projection tube) and a projection screen, a so-called videologictor, red,
The three primary colors green and blue are combined to create a color image. In any of the color television receivers mentioned above, red and green.

If the alignment of the three primary colors of blue, that is, the convergence adjustment, is not performed accurately, color misregistration will occur. Therefore, convergence adjustment can be said to be one of the important adjustments that affect image quality.

Here, convergence adjustment in a projection type color television receiver will be explained.

For example, as shown in FIG. 6, a projection type color ten vision receiver is equipped with a projection screen 1 and projection type cathode ray tubes 2, 3.4 each having red, green, and blue hues and having optical lenses. Red, green, and blue images obtained on the fluorescent surfaces of the cathode ray tubes 2, 3.4, respectively, are projected toward the projection screen 1 according to the video signal, etc., and a color image is formed on the projection screen 1. It is now displayed. By the way, when the cathode ray tubes 2, 3.4e are arranged in the horizontal direction, their respective projection angles with respect to the projection screen 1 are different. 4, a convergence adjustment coil (hereinafter referred to as a convergence coil) was provided separately from the main deflection coil, and a sawtooth wave current with a period equal to the horizontal scanning period (1H) was amplitude-modulated with a vertical period (1V) in this coil. It is sufficient to flow a current and adjust the amplitude of the current independently for each color. But each color.

The amount of color shift due to raster position shift is for each cathode ray tube 2.
, 3.4 mounting holes may vary in position, and each cathode ray tube 2
, 3.4, due to variations in the configuration of each optical lens system, fluctuations in the position of the projection screen 1, etc., it is difficult to pass a current that is a combination of a sawtooth wave current or a parabolic current through the convergence coil. Accuracy convergence adjustment cannot be performed.

As one method for realizing highly accurate convergence adjustment, a method using a digital convergence device having a digital correction waveform forming section is known, for example, as described in Japanese Patent Publication No. 59-8114. . This digital convergence device projects a dot pattern for convergence correction on the projection screen 1, and while watching this pattern, sequentially writes the data of the convergence correction amount for each dot into a digital memo 'J (RAM) of one frame. Data is sequentially read out and converted into an analog quantity by a D/A (digital/analog) converter, and a substantially sawtooth correction current is passed through a convergence coil to perform convergence correction.

[Problem that the invention seeks to solve]

By the way, in the digital convergence device described above, the H pulse (horizontal synchronization pulse) of the supplied video signal
From this, a pulse train having a pulse number that is an integral multiple of the H pulse is formed, and each dot is projected onto the screen 1 at a timing corresponding to each pulse of this pulse train. Further, an address signal for allocating an address when all data of the convergence correction amount is written and read out from the digital memory is also formed in accordance with each pulse of the pulse train.

That is, an address corresponding to each dot on the projection screen 1 is assigned at the evening timing corresponding to each pulse of the above-mentioned pulse train synchronized with the H pulse, and data of the convergence correction amount is written to and read from the digital memory. There is.

In such a digital convergence device, once the adjustment is completed by writing the data of the convergence correction amount for each dot into the digital memory while looking at the door pattern projected on the projection screen 1,
The raster size of the image projected on the projection screen 1, the raster position (centering), the frequency of the synchronizing signal of the supplied video signal, etc. have changed due to external factors such as temperature, or have been intentionally changed. There are cases where In such a case, the readout timing of the convergence correction amount data is different from the time of convergence adjustment, and it becomes impossible to obtain the predetermined convergence correction amount data corresponding to the absolute position of the projection screen 1. This is because, regardless of the absolute position on the projection screen 1, the data of the convergence correction amount is read out at a timing corresponding to each pulse of the pulse train. Therefore, there is a problem that the adjustment must be made again and the data of the convergence correction amount must be rewritten. In addition, especially when the frequency of the synchronizing signal of the supplied video signal changes, it is necessary to adjust the time constants of the pulse train generation circuit that determines the timing of reading data from the digital memory and the interpolation circuit that performs smoothing. There are problems such as the need for a new complicated corner circuit.

Therefore, the present invention has been made in view of the above-mentioned problems of the conventional technology.If, after completing the convergence adjustment, the lasqueue size, the lascoux position, the frequency of the synchronization signal of the supplied video signal, etc. change, It is an object of the present invention to provide a digital convergence device that can perform good convergence correction without any readjustment.

[Means for solving problems]

In order to achieve the above-mentioned object, the digital convergence device according to the present invention includes a digital memory that stores data on the amount of convergence correction corresponding to each convergence adjustment point, and a signal that is proportional to the deflection current flowing through the vertical deflection coil. a first A/'D conversion circuit that converts a signal proportional to the deflection current flowing through the horizontal deflection coil into a digital quantity; an address generation circuit that specifies a write address and a read address of the digital memory based on data from the width conversion circuit; and a D/A that converts the convergence correction amount data read from the digital memory into an analog amount. The device is equipped with a conversion circuit, and the output signal from the D/A conversion circuit is supplied to a convergence correction coil to perform all convergence correction.

[For production]

According to the present invention, the absolute position on the screen or tube surface is detected by detecting the deflection current, and the address of the digital memory is made to correspond to this absolute position to write and read data of the convergence correction amount. Therefore, good convergence correction can always be performed.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a digital convergence device for a projection type color television receiver, so-called a video projector, to which the present invention is applied. In FIG. 1, a test pattern generation circuit 11 is a signal generation circuit that generates a video signal VTPk that displays a test pattern used at the time of convergence adjustment, for example, Donotobakoon. The video signal VTP generated by the test pattern generation circuit 11 is sent to the video processing circuit 12 and converted into each primary color signal. 15 and a test pattern is projected on a projection screen 16. Further, the clock generation circuit 17 is an A/D conversion circuit (analog/digital conversion circuit) 1 which will be described later.
8, 19, address generation circuit 20, digital memory 2
1, and D/A/interpolation circuit (digital/analog conversion circuit/interpolation circuit) 22.23.24, 25, 26.27
supplies the clock. The operation timing of this clock generation circuit 17 is controlled by the timing clock from the test pattern generation circuit 11.

The signal input terminal 30 and the signal input terminal 31 receive a signal SV proportional to the deflection current 7 flowing through the vertical main deflection coil of one of the projection type cathode ray tubes 13, 14, and 15.
and a signal SH proportional to the deflection current IH flowing through the horizontal main deflection coil. Here, the deflection current supplied to the projection type cathode ray tube 14 for green color will be used as an example. The above-mentioned signals Sv and SH are respectively converted into digital quantities by digital conversion circuits 18 and 19, and are converted into digital quantities by the respective conversion circuits 18 and 19. Position data y in the direction is supplied to the address generation circuit 20. That is, since the position of the beam spot on the projection screen 16 is determined by the deflection current ■V+IH, the deflection current Iv r IH
Data indicating the absolute position (x, y)'c on the projection screen 16 can be obtained from the signal Sv + SH which is proportional to . Further, the digital memory 21 is stored at a plurality of predetermined positions (x n + ym ) on the projection screen 16.
An address Anm is set corresponding to 9, and data of a predetermined convergence correction amount corresponding to a position (xn, ym) on the projection screen 16 is stored in each of these address AnmLD memory cells. The address AnlTl of the digital memory 21 may correspond to the position of each dot of the dot pattern projected on the projection screen 16, for example.

Then, in accordance with the data indicating the position (x, y)k, the address Anm corresponding to the position ('Xn1.Ym)K is specified in the address generation circuit 20, and the address Anm corresponding to the position ('Xn1.Ym)K is specified from the digital memory 21. Data of predetermined convergence correction amounts are sequentially read out. In reality, the address An of the digital memory 21 is
The position data (Xn, ym) corresponding to the convergence correction amount data stored in m and the pJD conversion circuit i
The position data (x, y) obtained by 8.19 does not necessarily match. Therefore, the A/D conversion circuit 18
．． Position data (x, y)k obtained by 19k Address Anl of digital memory 21 set in advance
Compare the position data (Xn, yrn)'e corresponding to Tl and find the position (Xn, yrn) Kl that is closest to the position (x, y).
” and determines the address Anm.

Of the convergence correction amount data read out from the digital memory 21, the data for red is sent to the D/A/interpolation circuit 22.25, and the data for green is sent to the interpolation circuit 23.25.
26, data for blue is D/A/interpolation circuit 24.27
are sent to each. Here, each D/A/interpolation circuit 22
, 23 and 24 perform vertical interpolation processing (smoothing) between dot pitches after conversion to (digital/analog conversion)), and each D/A interpolation circuit 25
．． 26 and 27 perform horizontal interpolation processing after D/A conversion. Then, the D/A/interpolation circuit 22
Each convergence correction signal SRV r SRH for red obtained at ゜25 is sent from each signal output terminal 32.35 to each convergence correction signal SGV r for green obtained at D/A/interpolation circuit 23.26. 5GI (from each signal output terminal 33.36, D/A/interpolation circuit 24゜2
Each convergence correction signal S for blue obtained in step 7
BV r 5BI (is output from each signal output terminal 34.37, and each projection type cathode ray tube 13° 14.15
The convergence coil is supplied. In this way, convergence is corrected.

Further, writing of data to the digital memory 21 is performed, for example, as follows. The CPU (central processing circuit) 28 is connected to the address generation circuit 20゜digital memory 2.
1. and the keyboard 29, respectively.
While looking at the dot pattern projected on the projection screen 16, operate the keyboard 29 to select the position (x H + 'Irn) where convergence correction is required.
pf is selected and, for example, a red convergence correction amount is set.

Then, the address generating circuit 2o determines the position of the dot (xn+ym
) is specified, and the data of the red color convergence correction amount is written. By repeating such operations, data on red convergence correction amounts for all dots of the dot pattern projected on the projection screen 16 can be sequentially written into the digital memory 21. Further, by performing the same operation for green and blue, it is possible to write the data of the respective convergence correction amounts into the digital memory 21.

Note that when performing correction from a state in which the convergence is completely out of alignment, it is more efficient to perform an adjustment similar to correction using an analog system using sawtooth wave current or parabolic current. That is, it is desirable to rewrite all the data at the address related to the position of the dot almost simultaneously by adjusting the dot (1 door). Conventionally, this rewriting was performed during the vertical blanking period of the video signal, making it impossible to rewrite a large amount of data in a short period of time. However, in the digital convergence device of this embodiment, the digital memory 21 The memory is divided into two parts corresponding to the upper half and the lower half, respectively, and the memory that is not being read is connected to the CPU 28 so that a large amount of data can be rewritten almost simultaneously.

The operation of this digital convergence device will be specifically explained below using FIG. 2(A) and FIG. 2(Bi). signal SH is supplied.)
For example, as shown in FIG. 2(A), from time t1 to time t,
When the current value increases continuously from 11 to i during the scanning period Ts of approximately sawtooth, the projection screen 16 shows the projected image as shown in FIG. 2(B). Assume that a screen having a raster size (indicated by a broken line) that is slightly smaller than the size of the screen 16 is displayed. Note that since the - scanning line will be explained here, illustration of the deflection current Iv flowing through the vertical deflection coil will be omitted.

That is, the current value 11 of the deflection current IH at time t1
When the beam is deflected by P, the beam spot is located at a point P on the screen 16. Similarly, when the beam is deflected by each current value 12 to lo, the beam spot is located at each point P2 to P, respectively. and,
When adjusting the convergence by considering each of these points R-Pok as, for example, each dot of a dot pattern, for example, the deflection current 1. The data of the convergence correction amount is stored in the digital memory 2 in correspondence with each of the current values 11 to 19 of the digital memory 21, respectively.
It is set to be written to 1.

When reading the data of the convergence correction amount, the address of the digital memory 21 is specified based on the signal SH proportional to the deflection current IH supplied to the signal input terminal 31. Data on a predetermined convergence correction amount corresponding to the absolute position on the screen 16 can be obtained.Therefore, good convergence correction can be performed.

In addition, once the convergence adjustment is completed, as shown in FIG. and change the raster size to Figure 3 (B
) Even when the value of the deflection current IH is made small as shown in FIG.
6, it is possible to obtain data on a predetermined convergence correction amount for the absolute position. Therefore, good convergence correction can be performed without readjustment.

Furthermore, as shown in FIG. 4(A), the deflection current ■H is changed to a current such that the current value increases from i4 to i18 during the scanning period Ts from time t1 to time t, and the raster position is changed to i4 to i18. 4
Even when shifted to the right as shown in Figure (B), good convergence correction can be performed for the same reason.

Furthermore, as shown in FIG. 5(A), when the scanning period Tse of the deflection current IN is shortened to time t, ~t, corresponding to the horizontal synchronization signal of the video signal, that is, when the frequency is increased, the raster size and raster position change. As shown in FIG. 5(B), although this is the same as during convergence adjustment, the amount of beam deflection per unit time changes. However, even in this case, good convergence correction can be performed for the same reason. In addition, in this case, there is no need for a complicated peripheral circuit for fully adjusting the time constant of the interpolation circuit that performs smoothing, which was required in the past.

In the above explanation, the raster size, raster position, and frequency of the horizontal synchronization signal of the video signal were each intentionally changed. There may be slight changes. However, in this case as well, good convergence correction can of course be performed.

Further, the present invention is not limited to projection type color television receivers, but can also be applied to digital convergence devices for ordinary color television receivers using cathode ray tubes (CRTs).

〔Effect of the invention〕

As is clear from the above description of the embodiments, according to the present invention, the position of the full-beam spot, that is, the projection screen or tube surface, is determined by detecting the deflection current flowing in the vertical deflection coil and the deflection current flowing in the horizontal deflection coil. The raster size and
Even if the raster position, the frequency of the supplied video signal synchronization signal, etc. change, good convergence correction can be performed without readjustment.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a digital convergence device according to the present invention, and FIGS. 2(A) and 2(B) are waveform diagrams showing an example of deflection current during convergence adjustment and a projection screen. 3(A) and 3(B) are a waveform diagram showing the deflection current when the raster size is reduced, and a schematic diagram showing the state of the image on the projection screen. 4(A) and 4(B) are a waveform diagram showing the deflection current when the raster position is shifted to the right, a schematic diagram showing the state of the image on the projection screen, and FIG. 5(A). ) and FIG. 5(B) are waveform diagrams showing the deflection current when the frequency is increased and a schematic diagram showing the state of the image on the projection screen. FIG. 6 is a perspective view showing the main structure of a projection type color television receiver, and FIG. 7 is a schematic diagram showing the projection raster of each color.

Claims (1)

[Claims] A digital memory that stores convergence correction amount data corresponding to each convergence adjustment point, a first A/D conversion circuit that converts a signal proportional to the deflection current flowing through the vertical deflection coil into a digital amount, and a horizontal deflection coil. A second A/D conversion circuit that converts a signal proportional to the flowing deflection current into a digital quantity, and a write address and a read address of the digital memory based on data from the first and second A/D conversion circuits. and a D/A conversion circuit that converts the convergence correction amount data read from the digital memory into an analog amount, and the output signal from this D/A conversion circuit is used for convergence correction. A digital convergence device that corrects convergence by supplying power to the coil.