JPH10136396A - Automatic convergence correction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the reference pattern of an overscanning part from entering a visual field even when a deflection amplitude fluctuates by enlarging a deflection amount at the overscanning part more than the deflection amount inside a screen. SOLUTION: A CPU 8 first performs rough correction by making the time constant of a filter 22c small and then, performs fine correction by making the time constant large. Also, in the system of projecting the reference pattern to the overscanning part, from the relation of a projection angle, the overscanning of a specified color especially in a horizontal direction lacks. In the constitution, horizontal direction overscanning is enlarged and the reference pattern is prevented from entering the inside of the visual field. To put it concretely, the overscanning part is detected by the comparison of horizontal sawtooth-shaped waves HS and a fixed DC level by a comparator circuit 9b, a beam deflection amount is enlarged on a right side by a convergence correction circuit 18 and the convergence correction of the overscanning part on the right side is deformed in an enlarging direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to automatic correction of static convergence in a projection television receiver.

[0002]

2. Description of the Related Art Projection-type televisions can be easily realized with a large screen, thinner and lighter than a direct-view tube type.
The biggest challenge at the moment is convergence,
Eliminating installation adjustments and improving drift.

Generally, in a projection type color television receiver which emits three primary colors from individual picture tubes and enlarges and projects them on a screen, a color shift occurs on the screen. Therefore, the three primary colors are superimposed, that is, convergence correction is performed. is important.

In particular, in the case of the rear projection type, the projection distance is shortened due to the reduction in the thickness of the image receiver, the angle of incidence on a different screen for each picture tube is increased, raster distortion is increased, and the convergence correction amount is increased. Therefore, it is easily affected by geomagnetism and temperature drift.

[0005] In conventional commercial projection television receivers, it is necessary to adjust the static convergence at the time of installation. If the receiver is changed due to a change in the orientation of the receiver or drift due to temperature, etc. The user had to make that adjustment.

In order to solve this problem, a method has been proposed in which a photoelectric conversion element is provided at the periphery of a screen, a convergence reference pattern superimposed on a video signal is received, and convergence is corrected based on a measured shift. Have been.

For example, JP-A-63-209388,
JP-A-63-224572, JP-A-63-283383, JP-A-Hei 4
-282993 and JP-A-5-191817.
Hereinafter, a conventional automatic static convergence correction device for a projection television receiver as described above will be described with reference to the drawings.

FIG. 5 shows a configuration example of a conventional automatic static convergence correction device. In FIG. 5, a video signal input from a terminal 11 is a CRT 13.
Is projected on the screen 15 to form an image on the screen 15. The deflection circuit 20 and the deflection yoke 21 perform horizontal and vertical beam deflection.

As shown in FIG. 6, the photoelectric conversion element 1 is arranged at the lower center of the screen 15 and the photoelectric conversion element 2 is arranged at substantially the center on the right side of the screen 15. The components of the static convergence other than the photoelectric conversion elements include the center position detection circuits 3a and 3b, the storage circuits 4a and 4b, the pattern signal generation circuit 19, and the convergence correction circuit 18.

The operation of the thus configured automatic static convergence correction circuit will be described below. First, a pattern serving as a reference signal is generated from the pattern signal generator 19 and input to the video circuit 12 to display the pattern at the right electrical center outside the screen 15 and at the lower electrical center.

The center position detection circuits 3a and 3b detect a deviation from the center of the photoelectric conversion element and the display position of the pattern. The storage circuits 4a and 4b store the amount of deviation for each of R, G, and B colors. The convergence correction circuit 18 corrects static convergence so that the deviation for each color is minimized.

[0012]

However, the above configuration has the following problems. (1) Correction range is narrow ... ・ Considering the influence of terrestrial magnetism, aging of structure, and drift of CRT and correction circuit,
20 mm for a 45-cm thin type with a 43-inch screen
Although a wide correction range is required, in order to widen the detection range of the reference pattern, it has conventionally been necessary to use an expensive linear sensor or arrange many spot sensors. This complicates the detection circuit. (2) Malfunction when non-standard signal: Normal operation when a normal standard signal is used, but when horizontal and vertical frequencies deviate from the standard for VTR playback, etc. Patterns may come into view. (3) In some cases, the reference pattern signal of the overscan section may be seen. The overscan of the receiver is generally set within about 10%. May fluctuate, and the reference pattern of the overscan portion may enter the field of view.

An object of the present invention is to provide an automatic convergence correcting apparatus which improves the above-mentioned problems and has a configuration as simple as possible in terms of cost.

[0014]

The automatic convergence correction apparatus according to the present invention is characterized in that the amount of deflection in the overscan portion is made larger than the amount of deflection in the screen of the screen.

According to the present invention, it is possible to avoid a situation in which the reference pattern of the overscan section enters the field of view even if the deflection amplitude fluctuates due to a change in high voltage due to a change in luminance of an image receiving signal.

[0016]

According to the first aspect of the present invention, there is provided an automatic convergence correction device for projecting a convergence correction reference pattern onto an overscan portion around a screen.
In an automatic convergence correction device for detecting the reference pattern by a light detection unit and correcting a convergence deviation according to a projection position deviation of the reference pattern, an overscan detection unit for detecting the overscan portion is provided. A deflection circuit or a convergence correction circuit is controlled by a detection signal so that the amount of deflection in the overscan portion is made larger than the amount of deflection in the screen of the screen.

According to this configuration, the light detecting means is arranged at a position farther from the screen (view) of the screen, and the reference pattern is displayed at a position farther from the screen (view) of the screen to automatically correct the convergence. Even if the deflection amplitude fluctuates due to a change in high voltage or the like, the reference pattern of the overscan section does not enter the field of view.

According to a second aspect of the present invention, there is provided an automatic convergence correction device for projecting a convergence correction reference pattern on an overscan portion around a screen of a screen, detecting the reference pattern with light detecting means, and detecting a projection position shift of the reference pattern. In the automatic convergence correction device for correcting the convergence deviation according to
A smoothing circuit having a WM output, a comparison circuit for comparing the output voltage of the smoothing circuit with a horizontal or vertical deflection current waveform or a waveform proportional thereto, and a generation timing of a reference pattern signal determined by a pulse from the comparison circuit A waveform generating circuit that performs a rough correction by first reducing the time constant of the smoothing circuit and then performing a precise correction by increasing the time constant. And

An embodiment of the present invention will be described below with reference to FIGS. 5 and 6 showing the conventional example will be described with the same reference numerals.

FIG. 1 shows an automatic convergence correcting apparatus according to the present invention. Actually, three tubes for red, green, and blue are necessary for the CRT 13, the lens 14, and the like, but only one is shown in FIG. Reference numeral 16 denotes an input terminal for a vertical synchronization signal, and reference numeral 17 denotes an input terminal for a horizontal synchronization signal.

As shown in FIG. 2, the photoelectric conversion elements 1a, 1
b is a photoelectric conversion element 2a,
2b is arranged at the center on the right side of the screen 15.
FIG. 3 is an enlarged view of the photoelectric conversion elements 2a and 2b for detecting the position in the vertical direction on the right side of the screen. The reference pattern 24 for position detection in the vertical direction is a horizontal line so that it does not deviate from the photoelectric conversion elements 2a and 2b even when the raster amplitude changes. Similarly, the reference pattern in the horizontal direction is a vertical line.

The switch 5 includes photoelectric conversion elements 1a, 1b, 2
The detection signals of the photoelectric conversion elements 1a and 1b are output when the switching state is H, and the detection signals of the photoelectric conversion elements 2a and 2b are output when the switching state is V. It is configured to be.

The peak hold circuits 6a and 6b detect and hold the peak of the output signal of the switch 5. AD converter 7
a and 7b digitally convert the outputs of the peak hold circuits 6a and 6b.

In addition to the above, the present apparatus has a C for controlling the present apparatus.
PU8, convergence correction circuit 18, comparison circuit 9a,
9b, a nonvolatile memory 10, an on-screen position control DA converter 22a for controlling where the reference pattern is displayed on the raster, a static convergence correction DA converter 22b for controlling the entire raster position,
It is composed of a filter 22c and the like.

The operation of the television receiver configured as described above will be described with reference to FIG.
This automatic convergence correction device performs the following four basic functions under the control of the CPU 8 as a control unit with the above configuration. (1) Project a reference signal onto the screen ... The reference pattern is an on-screen signal, which is controlled by the CPU 8 from the on-screen signal generation circuit 19 to the video circuit 1.
2 and projected on the photoelectric conversion element outside the screen. (2) Detecting whether or not the reference signal is at the center of the photoelectric conversion element ... The output signal of the photoelectric conversion element is peak-held by the peak hold circuits 6a and 6b via the switch 5, and is subjected to AD conversion. CPU 8 via devices 7a and 7b
Is input to The CPU 8 sets the switch 5 to the H side to detect the light input of the photoelectric conversion elements 1a and 1b by the reference signal in the horizontal direction, and confirms whether the reference pattern is at the center of the two photoelectric conversion elements. CPU 8 is the photoelectric conversion element 1
When the outputs of a and 1b become the same, it is determined that the pattern is at the center. (3) Move the position of the on-screen signal on the raster... The horizontal movement moves the position of the on-screen signal in the on-screen position control DA converter 22a of the CPU 8 (the raster does not move). Movement in the vertical direction depends on the number of the raster display line of the reference pattern. (4) Perform raster movement (static convergence correction): Data is sent from the CPU 8 to the DA converter 22b for static convergence correction, and the entire raster is moved by controlling the convergence coil 23.

The CPU 8 measures the position of the reference signal periodically and corrects the static convergence if there is a raster shift by using the above basic functions. Hereinafter, the horizontal correction will be described first.

This system requires the following two initial adjustments: "determination of correction value of DA converter" and "storage of reference position". The correction value of the D / A converter is determined by measuring the correlation between the amount of movement of the raster by the convergence correction D / A converter 22b and the amount of movement of the reference pattern by the on-screen D / A converter 22a.
A conversion coefficient for converting the deviation amount of the reference pattern obtained in the above into a corresponding correction amount of the convergence correction DA converter 22b is obtained.

The reference position is stored, for example, by outputting a cross white adjustment signal near the center of the screen, and visually checking the red, green, and red signals.
Adjust the static convergence correction amount so that the blue color shift is eliminated. Next, the CPU instructs the CPU to move the position of the reference pattern by the output of the on-screen position control DA converter 22a so that the reference pattern is located at the center of the two photoelectric conversion elements.
The output value to a is stored in the memory 10 as a reference value.

Under the conditions of the above initial adjustment, the reference pattern is moved periodically thereafter, and the value of the position control DA converter 22a which is the center position of the photoelectric conversion element is measured. If there is a deviation, it is determined that a convergence deviation has occurred, and the correction amount of the static convergence is changed so that control is performed such that the reference value comes to the center position of the two photoelectric conversion elements. As a result, the position of the raster has returned to the default position. By performing this for the three primary colors of red, green and blue, the color shift can be corrected.

In the vertical direction, the manner of moving the reference pattern is different as described above, but the other operations are the same. Convergence correction operations include horizontal red, green, blue,
One correction operation is performed by performing time-sharing such as red, green, and blue in the vertical direction. This correction operation is performed immediately after the power is turned on and periodically thereafter, thereby automatically correcting the static convergence deviation.

Since it is difficult to obtain accuracy in a single measurement of the convergence deviation, the accuracy is improved by programming the correction operation to repeat several times until the convergence is converged within a certain range. As a result, it is possible to avoid abnormalities in the measured value of the movement of the raster due to non-synchronous non-standard signals or extraneous noise, such as the reproduction of a video tape recorder.

As described above, the convergence automatic correction apparatus according to the present embodiment performs the correction operation in a time-division manner.
The photoelectric conversion element can be shared by red, green, and blue, and has a feature that a simple circuit configuration can be achieved.

However, due to the time-sharing control and the repetitive operation for improving the accuracy, the time until the correction is completed may become a problem. In particular, as a DA converter for which the CPU 8 performs position control, a DA converter of about 12 bits is basically required for precise control. When the D / A converter 22a is used, the PWM signal is smoothed to a DC voltage for control by the filter 22c. However, the position detection is repeated many times to improve the accuracy.
A delay occurs due to the time constant of c. To cover these, the present invention is configured as follows.

The CPU 8 is configured to first make the time constant of the filter 22c small and make a rough correction, and then make the time constant large and make a precise correction. In the method of projecting the reference pattern onto the overscan section as in the present invention, the overscan of a specific color in the horizontal direction is insufficient due to the projection angle.

In the present invention, the horizontal overscan is enlarged to prevent the reference pattern from entering the field of view. Hereinafter, a specific description will be given with reference to FIGS. 3 and 4.

The comparison circuit 9b in FIG. 1 compares the horizontal sawtooth signal HS with a constant DC level to detect an overscan portion, and the convergence correction circuit 18 enlarges the beam deflection amount on the right side as shown in FIG. The convergence correction of the overscan section is deformed in the enlargement direction.

FIG. 3 shows a portion of the photoelectric conversion elements 2a and 2b on the right side of the screen for detecting in the vertical direction, whereby the overscan on the right side of the screen is indicated by a broken line A (in the case where the amount of deflection is the same as that in the screen of the screen). Position) to the solid line portion B.

In this way, the overscan can be expanded without narrowing the field of view, and the photoelectric conversion element can be arranged at the back, so that the reference pattern can be prevented from being seen when the amplitude changes. If necessary, the overscan can be similarly expanded for the horizontal detection unit (the lower part of the screen).

The overscan enlargement correction is performed by the convergence correction circuit 18, but may be performed by a deflection circuit. In the above-described embodiment, the AD converter, the DA converter, and the on-screen signal generation circuit are configured separately from the CPU 8, but these can be configured with either the built-in CPU 8 or external elements. Although the present invention has been described with reference to the automatic correction of static convergence, the present invention can also be applied to automatic correction of dynamic convergence.

[0040]

As described above, according to the present invention, the overscan detecting means for detecting the overscan portion is provided, and the deflection circuit or the convergence correction circuit is controlled by the detection signal of the overscan detecting means, so that the overscan is performed. Because the amount of deflection at the part is larger than the amount of deflection in the screen of the screen, it is strong against amplitude fluctuation,
The configuration can be simplified to prevent the reference pattern from entering the field of view.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an automatic convergence correction device according to an embodiment of the present invention.

FIG. 2 is a front view showing an arrangement relationship between the photoelectric conversion element and a screen according to the embodiment.

FIG. 3 is an enlarged view of a photoelectric conversion unit on the right side of the screen according to the embodiment;

FIG. 4 is an explanatory diagram of overscan enlargement of the embodiment.

FIG. 5 is a configuration diagram of a conventional convergence automatic correction device.

FIG. 6 is a front view showing an arrangement relationship between a photoelectric conversion element and a screen of the conventional example.

[Explanation of symbols]

1a, 1b, 2a, 2b Photoelectric conversion element 8 CPU [Control unit] 9b Comparison circuit 13 CRT 14 Lens 15 Screen 18 Convergence correction circuit 22a DA converter for on-screen position control 22b DA converter for static convergence correction 22c Filter 23 Convergence Coil 24 Reference pattern

Claims (2)

[Claims] 1. A convergence correction reference pattern is projected on an overscan portion around a screen of a screen,
In the automatic convergence correction device for detecting the reference pattern by the light detection unit and correcting the convergence deviation in accordance with the projection position deviation of the reference pattern, an overscan detection unit for detecting the overscan portion is provided. An automatic convergence correction device configured to control a deflection circuit or a convergence correction circuit with a detection signal so that the deflection amount in the overscan portion is larger than the deflection amount in the screen of the screen. 2. A convergence correction reference pattern is projected on an overscan portion around the screen of the screen,
In a convergence automatic correction device for detecting the reference pattern by a light detecting means and correcting a convergence deviation according to a projection position deviation of the reference pattern, a PWM output smoothing circuit output from a control unit, and an output voltage of the smoothing circuit And a comparison circuit for comparing the horizontal or vertical deflection current waveform or a waveform proportional thereto, and a waveform generation circuit for determining the generation timing of the reference pattern signal by a pulse from the comparison circuit, An automatic convergence correction device configured to first make a rough correction by reducing the time constant of the smoothing circuit and then to make a fine correction by increasing the time constant.