JPH0654987B2 - Digital convergence device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital convergence device capable of adjusting convergence correction of a color television receiver quickly and accurately.

2. Description of the Related Art As is well known, a shadow mask type color cathode ray tube (hereinafter abbreviated as CRT) used in a general color television receiver has three electron guns of red, green and blue. However, since it is structurally impossible to arrange all of these electron guns on the central axis of the CRT, the electron guns are mounted at a slight distance from the central axis and slightly inclined inward with respect to the central axis. Therefore, in the screen on the central axis, each electron beam converges at the shadow mask, and at the same time, the fluorescent dots of red, green, and blue are emitted through the same hole, and a state of convergence is achieved.
However, since the radius of curvature of the shadow mask is larger than the distance from the deflection center to the center of the shadow mask,
Except for the central axis of the CRT, the three electron beams converge before the shadow mask. Therefore, the three electron beams cannot pass through the same hole at the same time, and the reproduced image has a larger color shift or convergence shift as the distance from the center of the screen increases. In order to prevent such an inconvenience, it is necessary to perform convergence correction so that the three electron beams converge at the shadow mask over the entire screen.

In addition, in a projection type color image receiver that projects enlargedly on a screen using three CRTs that emit three primary colors, CR
Since the incident angle of T with respect to the screen is different for each CRT, color shift occurs on the screen.

The superposition of these three primary colors, so-called convergence, is generally a method of obtaining a convergence correction waveform in an analog manner by using passive elements such as L, C, and R from horizontal flyback pulse and vertical deflection deformation. However, there is a problem in terms of convergence accuracy. On the other hand, as a method for more accurate convergence,
A method of digitally performing convergence correction has been proposed.

The concept is to project a convergence correction pattern such as a crosshatch or dot on the screen, digitally write the convergence correction amount data for each point into one frame memory, and then write this written information in horizontal scanning and vertical scanning. The data is read out in synchronism with, and D / A converted / amplified to perform convergence correction. A description will be given below with reference to FIGS. 2 and 4.

First, as shown in FIG.
From the hatch generator 9, a crosshatch showing the adjustment points of 7 columns in the vertical direction is displayed. The intersection of this crosshatch is the adjustment point.

Here, first, the cursor key 1 on the control panel 14
When the adjustment point is selected with 0, the CPU 15 obtains the cursor address of the adjustment point and sets the cursor in the register for displaying the cursor. At this time, the address of the one-frame memory 3 is also obtained. Next, while looking at the screen with the data write key 11 for the color to be corrected, for example, red, desired data is written to the designated address of the 1-frame memory 3. The same applies to all adjustment points on the screen.

Next, reading of the convergence correction amount written in the 1-frame memory 3 will be described. Since the 1-frame memory 3 has only the correction data at the positions corresponding to the adjustment points, it is necessary to interpolate each scanning line between the adjustment points in the vertical direction. Therefore, for example, by using the correction data of the first and second rows read from the 1-frame memory 3, the correction amount at the scanning line included between the adjustment points of the first and second rows is calculated. It is calculated by the interpolation calculation circuit 4. Next, the output signal of the interpolation calculation circuit 4 is converted into an analog amount by the D / A converter 5, smoothed by the low pass filter (LPF) 6, and the amplifier 7
Amplify at and supply to the convergence yoke.

In the digital convergence device described above, the adjustment points can be independently corrected as desired, so that the convergence correction can be performed accurately.

However, in order to perform accurate convergence correction, the quantization at each adjustment point must be increased, that is, the capacity of the 1-frame memory 3 must be increased. In order to solve this, for example, as shown in FIG. 3, a method of generating an analog convergence correction signal in the parabolic waveform generator 16 and mixing it with the correction data in the amplifier 7 through the line 17 is considered.

Problems to be Solved by the Invention However, the above-mentioned configuration has a problem that the digital correction amount must be set to zero by using the changeover switch 18 when adjusting the waveform of the parabolic waveform generator 16. It was

In view of the above problems, the present invention provides a digital convergence device capable of adjusting a digital correction amount to zero and adjusting an analog amount without using a changeover switch.

Means for Solving the Problems In order to solve the above problems, the digital convergence apparatus of the present invention has a CPU having a function of clearing one frame memory and setting the digital correction amount to zero.

Function The present invention can make the digital correction amount zero without the changeover switch by the above-mentioned configuration.

Embodiment A digital convergence device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of digital convergence in one embodiment of the present invention. In the figure, 1 is a control panel having a cursor key 10 and a writing key 11, 2 is a CPU, 16 is a parabolic generator for generating a parabolic signal in the form of an analog signal, 19 is a clear key for making the digital correction amount zero, It is provided in the control panel 1.

Next, the operation will be described.

First, the clear key 19 shown in FIG. 1 is used to clear the one-frame memory 3 via the CPU 2 to set the digital correction amount to zero. In this state, the screen convergence adjustment is performed by the parabolic waveform of the parabolic generator 16.

Next, the digital correction amount is written and read for each adjustment point by the same operation as that of the conventional convergence device, and the digital amount is added to the previous analog amount by the amplifier 7.

As described above, according to the present embodiment, by providing the CPU 2 with the function of setting the digital correction amount to zero, the changeover switch for turning off the digital correction amount becomes unnecessary.

EFFECTS OF THE INVENTION As described above, according to the present invention, the changeover switch for turning off the digital correction amount can be eliminated by providing the CPU with the function of making the digital correction amount zero.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a digital convergence device according to an embodiment of the present invention, and FIGS. 2 and 3 are block diagrams showing the configuration of a conventional digital convergence device.
FIG. 4 is a front view showing a projected state of a crosshatch signal for projecting a convergence adjustment point on a picture tube. 1 ... Control panel, 2 ... CPU, 16 ... Parabolic generator, 19 ... Clear key.

Claims (1)

[Claims] 1. A convergence device for correcting color shift of a color television receiver, wherein coarse adjustment is performed by analog convergence correction and then correction is accurately performed by digital convergence, in a horizontal direction and a vertical direction of a screen. Has a plurality of convergence adjustment points, means for inputting position information of the convergence adjustment points, means for storing data for correcting the convergence deviation of the adjustment points in a memory, and contents of the memory without initial correction. A digital convergence device having means for returning to a value.