JPH066623A - Display device - Google Patents

Abstract

PURPOSE:To prevent deterioration in picture quality specific to bidirectional deflection by detecting the light emission of an index pattern and correcting a forward and a backward display pattern based on the result of detection. CONSTITUTION:The device is provided with horizontal deflection circuits 10, 14, 16, 20, a cathode ray tube 8, cathode ray tube drive circuits 2, 6, index signal detection circuits 26, 28, 30 detecting the light emission of an index pattern P to output an index signal, and a display picture correction circuit 32 correcting the display picture of a forward path and a backward path so that the display picture formed by the forward deflection is made coincident with the display picture formed by the backward deflection based on the result of detection of the index signal detected in the setup mode. Then the index pattern P is formed in the cathode ray tube 8 and in the setup mode, a test signal ST is used to drive the cathode ray tube 8, the index signal is detected and in the display mode, the display picture of the forward path and the backward path is corrected based on the result of detection of the index signal.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology Problems to be Solved by the Invention (FIGS. 5 and 6) Means for Solving the Problems (FIG. 1) Action (FIG. 1) Embodiment (1) Configuration of Embodiment (FIG. 1) (FIG. 4) (2) Effects of the embodiment (3) Other embodiments Effects of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and is particularly suitable for application to a display device which forms a display image by applying a bidirectional deflection method.

[0003]

2. Description of the Related Art Conventionally, in a deflection circuit of this type, a horizontal deflection coil is formed by using a drive signal whose signal level changes symmetrically before and after a predetermined time point, such as a sine wave signal. A driving deflection circuit (hereinafter referred to as a bidirectional deflection deflection circuit) has been proposed (US Pat. No. 4,6,6).
72,449).

According to this bidirectional deflection circuit, scanning from left to right of the screen (hereinafter referred to as forward scanning) and conversely, scanning from right to left of the screen (hereinafter referred to as backward scanning) are performed. Together they can form a display image and reduce the deflection frequency by half.

Further, since it is possible to prevent a sharp change in the deflection current such as a sawtooth wave signal, it is possible to reduce unnecessary radiation and the like, and also to reduce the load on the deflection circuit element.

Particularly, if the deflection circuit is formed of a resonance circuit and the deflection coil is driven by a sinusoidal current, the power required for deflection can be reduced with a simple structure (Japanese Patent Laid-Open No. 3-72783).

[0007]

By the way, as shown in FIG. 5, in this bidirectional deflection, if the deflection timing is largely deviated in the forward and backward passes, the display screen is formed in duplicate and the display screen is unsightly. There is a feature.

Further, even if this timing deviation is small, the horizontal resolution is deteriorated, and the display screen becomes uncomfortable correspondingly.

On the other hand, if the deflection current changes differently on the forward and return paths, the display images on the forward and return paths are partially displaced as shown in FIG. 6, and the deflection timing is also displaced in this case. As in the case, there is a feature that the display screen becomes unsightly.

That is, in this type of bidirectional deflection,
In the case of raster scanning, the image quality of the display image is deteriorated even by the deflection timing, linearity change, etc., which is not a problem, and it is necessary to prevent this kind of image quality deterioration by some correction means.

As one of the methods of preventing the deterioration of image quality peculiar to this bidirectional deflection, for example, a phosphor is applied in a predetermined pattern in a cathode ray tube, and the light emission generated when the cathode scans this phosphor is detected. Can be considered.

That is, by detecting this light emission,
This is a method in which the beam position is detected by the outward and backward deflections and the detection result is fed back to the deflection circuit.

In the case of this method, it is considered that the display image can be corrected based on the actual beam position detection result, so that the image quality deterioration can be prevented reliably and with high accuracy.

However, in the case of this method, it is necessary to constantly pass the beam current in order to cause the phosphor to emit light, and the black level of the displayed image is raised to gray and displayed, and the contrast of the displayed image is lowered. There is.

In order to solve this problem, a method of setting the application position of the phosphor outside the effective area of the display screen and thereby preventing the deterioration of the contrast of the display image can be considered.

However, in this method, since the beam position cannot be detected for the actual display position, it is not possible to reliably prevent the deterioration of image quality.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose a display device capable of preventing the deterioration of the image quality peculiar to bidirectional deflection without impairing the image quality of a normal display image. To do.

[0018]

In order to solve such a problem, in the first invention, the deflection currents of the forward path and the backward path are supplied to the horizontal deflection coil 12 so that the display image is formed by the deflection of the forward path and the backward path. In the display device 1 for forming a display image by forming a horizontal deflection circuit 10, 14, 16 and 20 for driving the horizontal deflection coil 12 and an index pattern P of a predetermined shape which emits light when the cathode ray scans in the tube. The cathode ray tube 8, the cathode ray tube drive circuits 2 and 6 for driving the cathode ray tube 8 based on the video signal SV, and the index signal detection circuits 26 and 28 for detecting the light emission of the index pattern P and outputting the index signal. 30 and
In the set-up mode, a predetermined test signal ST is output to the cathode ray tube drive circuits 2 and 6 in place of the video signal SV to detect the index signal, and in the display mode, the detection result of the index signal detected in the set-up mode is displayed. As a reference, so that the display image formed by the outward deflection and the display image formed by the backward deflection are matched,
Display image correction circuit 3 for correcting display images on the outward path and the return path
2 and so on.

Further, in the second invention, the display image correction circuit 32 outputs the correction signal SF2 to the horizontal deflection circuits 10, 14, 16 and 20, and corrects the deflection timings of the forward and backward passes to thereby make the forward pass. The display image formed by the deflection and the display image formed by the return deflection are matched.

Further, in the third invention, the display image correction circuit 32 outputs the correction signal SF3 to the horizontal deflection circuits 10, 14, 16 and 20, and corrects the linearity of the deflection on the outward path and the backward path to thereby make the forward path. The display image formed by the deflection and the display image formed by the return deflection are matched.

Further, in the fourth invention, the display image correction circuit 32 sends the correction signal SF1 to the cathode ray tube drive circuits 2 and 6.
By correcting the drive signal output to the cathode ray tube 8 by the outward deflection and the drive signal output to the cathode ray tube 8 by the return deflection, the display image formed by the outward deflection and the return deflection are corrected. Match the formed display images.

Further, in the fifth invention, the horizontal deflection circuits 10, 14, 16 and 20 have a correction transformer connected in series to the horizontal deflection coil 12 and drive the correction transformer based on the correction signal SF3. The deflection current of the horizontal deflection coil 12 is corrected via the correction transformer.

Further, in the sixth invention, each of the horizontal deflection circuits 10, 14, 16 and 20 has a drive circuit 20 for a sub-deflection yoke 18 for correcting the horizontal deflection magnetic field formed by the horizontal deflection coil 12, and a correction signal SF4. The sub-deflection yoke 18 is driven based on

Further, in the seventh invention, the display image correction circuit 32 switches the operation mode to the set-up mode and then switches to the display mode when the power is turned on.

Further, in the eighth invention, the display image correction circuit 32 switches the operation mode from the display mode to the set-up mode in response to the operation of a predetermined operator.

[0026]

The index pattern P is formed in the cathode ray tube 8 and the test signal ST is set in the set-up mode.
If the cathode ray tube 8 is driven by, the index signal is detected, and the display image in the forward path and the return path is corrected based on the detection result of the index signal in the display mode, the image quality of the normal display image is deteriorated. Therefore, it is possible to prevent deterioration of image quality peculiar to bidirectional deflection.

At this time, the horizontal deflection circuits 10, 14, 16,
A correction signal SF2 is output to 20 to correct the forward and backward deflection timings, and the forward and backward deflection linearity is corrected so that the display image formed by the forward deflection and the backward deflection can be corrected. The formed display images can be made to coincide with each other, and deterioration in image quality peculiar to bidirectional deflection can be prevented in advance.

Further, even if the drive signal output to the cathode ray tube 8 by the outward deflection and the drive signal output to the cathode ray tube 8 by the backward deflection are corrected, the image quality deterioration peculiar to the bidirectional deflection can be prevented. it can.

On the other hand, if a correction transformer is connected in series to the horizontal deflection coil 12 and the deflection current of the horizontal deflection coil 12 is corrected via this correction transformer, the sub-deflection for correcting the horizontal deflection magnetic field is also obtained. Even if the yoke 18 is driven, the display image formed by the outward deflection and the display image formed by the backward deflection can be matched.

On the other hand, if the operation mode is switched when the power is turned on or when a predetermined operator is operated, the forward and backward display images can be corrected as needed.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) Configuration of the Embodiment In FIG. 1, reference numeral 1 denotes a display device as a whole, and bidirectional deflection is applied to form a display image.

That is, in the display device 1, the video signal SV is supplied to the video signal processing circuit 2, where after the predetermined signal processing is executed, the video signal SV is converted into a luminance signal and a color difference signal.

Further, in the video signal processing circuit 2, after converting the luminance signal and the color difference signal into a digital signal by the built-in analog digital conversion circuit, the odd number lines are converted into analog signals in the same order and output. On the other hand, for even-numbered lines, the arrangement is reversed and then converted into analog signals and output.

As a result, the video signal processing circuit 2 is adapted to convert the video signal SV into a video signal required for forward and backward scanning.

Further, the video signal processing circuit 2 uses the correction signal S
Based on F1, the timing of the digital-analog conversion circuit can be changed so that the output timing of the luminance signal and the color difference signal can be changed.

Further, in the video signal processing circuit 2, when the operation mode is switched from the display mode to the set-up mode, the test signal ST output from the predetermined signal generating circuit (SG) 4 is selected, and the test signal ST is selected. Is output instead of the luminance signal and the color difference signal.

The test signal ST is generated by the signal generating circuit 4 and is capable of displaying a full-white display image held at a predetermined brightness level.

The drive circuit 6 drives the cathode ray tube 8 based on the output signal of the video signal processing circuit 2.

The horizontal deflection circuit 10 is a bidirectional horizontal deflection circuit, and drives the horizontal deflection coil 12 so that the current value changes sinusoidally.

At this time, the horizontal deflection circuit 10 is controlled by the AFC circuit 14 to switch the deflection start timing of the forward path and the backward path, whereas the AFC circuit 14 uses the horizontal synchronizing signal HD as a reference. Control the timing of the start of deflection.

Further, the AFC circuit 14 corrects the deflection start timings of the forward path and the backward path according to the correction signal SF2, and thereby can correct the timing deviation of the forward path and the backward path of deflection.

As a result, in the display device 1, this A
The FC circuit 14 is used to prevent the image quality deterioration as described above with reference to FIG.

Further, the horizontal deflection circuit 10 is the distortion correction circuit 1
Based on the output signal of 6, the operation timing of the switching element that switches the deflection of the forward path and the return path is shifted, and thereby the asymmetry of the deflection current of the forward path and the return path is corrected.

At the same time, the horizontal deflection circuit 10 includes the distortion correction circuit 1
A parabolic signal having a predetermined shape is generated based on the output signal of No. 6, and the parabolic signal is superposed on the deflection current through a transformer connected in series to the horizontal deflection coil 12, thereby correcting the distortion such as pin distortion. To do.

The distortion correction circuit 16 switches the signal for distortion correction based on the correction signal SF3, so that in the display device 1, the correction signal SF of the distortion correction circuit 16 is changed.
3 is switched to prevent deterioration of image quality as described above with reference to FIG.

With respect to the deflection magnetic field formed by the horizontal deflection coil 12, the cathode ray tube 8 has an auxiliary deflection coil 18 arranged in the neck portion thereof, and the display device 1 includes the auxiliary deflection coil 18 in the sub DY drive circuit 20. Drive with.

The sub-DY drive circuit 20 receives the correction signal SF4.
The driving conditions of the auxiliary deflection coil 18 are switched on the basis of the above, and thereby the deflection magnetic field formed by the horizontal deflection coil 12 is corrected.

As a result, in the display device 1, even if the correction signal SF4 is switched, the image quality deterioration described above with reference to FIGS. 5 and 6 can be prevented.

On the other hand, the vertical deflection circuit 22 generates a deflection signal whose signal level changes stepwise on the basis of the vertical synchronization signal, and drives the vertical deflection coil 24 on the basis of this deflection signal. Accordingly, in the display device 1,
A vertical deflection magnetic field corresponding to bidirectional deflection is formed to drive the cathode ray tube 8.

Here, the cathode ray tube 8 is, as shown in FIG.
An index pattern P having a predetermined shape is repeatedly formed on the tube surface M vertically and horizontally with equal pitches.

The index pattern P is formed by applying a phosphor so that it emits light when the beam of the cathode ray tube 8 scans, extends vertically to the scan start end side of the outward path, and is obliquely adjacent to this. Is formed to extend to.

Further, in the cathode ray tube 8, a photodetector 26 is arranged on the upper rear surface so that the light emission of the index pattern P can be received.

Thus, the display device 1 can detect the timing of light emission of the index pattern P by displaying the test signal ST and monitoring the output signal of the photodetector 26 (hereinafter referred to as the index signal). The timing at which the beam scans the index pattern P can be detected based on the detection result.

Therefore, in the display device 1, the beam position can be detected based on the index signal.

The signal processing circuit 28 inputs the index signal through the amplifier circuit 30 and detects the rising edge of the index signal.

Further, the signal processing circuit 28 time-measures the rising edge of the index signal with reference to the horizontal synchronizing signal, and outputs the measurement result.

The correction circuit 32 inputs this time measurement result to an analog digital conversion circuit (A / D) 34, converts it into a digital signal, and converts it into a central processing unit (CP).
U) 36.

When the set-up operator is pressed, the central processing unit 36 switches the operation mode of the entire display device 1 from the display mode to the set-up mode.
The processing procedure shown in FIG. 3 is executed.

That is, the central processing unit 36 moves from step SP1 to step SP2, judges whether or not the set-up operator has been pressed, and if a negative result is obtained here, the process returns to step SP2.

On the other hand, when an affirmative result is obtained at step SP2, the central processing unit 36 proceeds to step SP3, switches the entire operation mode to the set-up mode, and displays the test signal ST on the cathode ray tube 8.

Further, in the central processing unit 36,
The time measurement results of the index signals are sequentially input from the analog digital conversion circuit 34 for each deflection of the forward path and the backward path,
At step SP4, the deviation of the beam position is detected based on the time measurement result.

That is, when the timing for scanning the index pattern is different from the deflection on the outward path and the deflection on the return path, the display image on the outward path and the display image on the return path are displayed with a shift in this portion.

Therefore, in the central processing unit 36,
In this case, it is determined that the displayed images do not match, and step SP
5, the time measurement result is stored in the memory circuit 38.

Further, the central processing unit 36 proceeds to step SP6 to access the correction data stored in the memory circuit 38 to generate the correction data on the basis of the time measurement result, and the correction data is digitally analogized. Output to the conversion circuit (D / A) 40.

As a result, the central processing unit 36 changes the correction signals SF1 to SF4, which have been output until then, based on the detection result of the index signal, and then returns to step SP3.

In other words, based on the time measurement result, when the forward and backward display images are shifted to the left and right as a whole,
In the central processing unit 36, the correction signal SF2 of the AFC circuit 14 is changed, whereas when this shift amount is small, the correction signal SF1 of the video signal processing circuit 2 is changed to switch the timing of the luminance signal and the color difference signal. .

As a result, in the central processing unit 36, the deviation of the display image as described above with reference to FIG. 5 is corrected and the deterioration of the image quality is prevented.

On the other hand, the central processing unit 36 changes the correction signal SF3 of the distortion correction circuit 16 when the sizes of the forward and backward display images are displaced as a whole, whereas when the displacement is small. The correction signal SF1 of the video signal processing circuit 2 is changed to switch the timing of the luminance signal and the color difference signal.

As a result, the central processing unit 36 corrects the deviation of the display image as described above with reference to FIG.

On the other hand, when the display image is locally deviated, the central processing unit 36 changes the correction signal SF3 of the distortion correction circuit 16, and when the correction signal SF3 cannot be completely corrected, the sub DY drive circuit 20 is changed. The correction signal SF4 of is changed.

In the correction signal changing process, the central processing unit 36 performs steps SP3-SP4-SP5-SP6-.
By repeating the processing loop of SP3, it is repeatedly executed so as to improve the image quality of the entire display screen.
As a result, when the amount of deviation for each index pattern P becomes less than a certain value, a negative result is obtained in step SP4, and the central processing unit 36 moves to step SP7 to complete the set-up mode.

In this way, in the display device 1, the forward and backward display images can be matched with each other with high accuracy by sequentially correcting the horizontal deflection timing and the like, thereby preventing the image quality deterioration peculiar to the bidirectional deflection. Can be prevented.

Further, in this embodiment, the central processing unit 36 is adapted to execute the correction processing such as the convergence when the positional deviation of the display image is thus corrected, so that the display device 1 always operates. It is designed to display a high quality display image.

Thus, in the central processing unit 36, when the set-up mode is completed, the entire operation mode is switched to the display mode, and each circuit block is driven by the correction signals SF1 to SF4 set in the set-up mode at this time.

As a result, the user can obtain a high-quality display image only by pressing the set-up operator at a desired timing, even if the circuit components of the deflection circuit change over time and the characteristics change. be able to.

(2) Effects of the Embodiments According to the above construction, an index pattern is formed on the cathode ray tube, and the deviation between the forward and backward display images is detected based on the detection result of the index signal in the set-up mode. However, by generating the correction signal so as to correct this deviation, it is possible to prevent the deterioration of the image quality peculiar to the bidirectional deflection, without impairing the image quality of the normal display image.

(3) Other Embodiments In the above-mentioned embodiments, the case where the index pattern is formed by straight lines and diagonal lines has been described, but the present invention is not limited to this and, for example, as shown in FIG. Alternatively, the phosphor may be applied so as to extend linearly from the upper end to the lower end of the screen, thereby forming an index pattern.

Further, in the above-mentioned embodiment, the case where the correction signal is automatically changed in the set-up mode has been described, but the present invention is not limited to this and may be manually adjusted.

Further, in the above-mentioned embodiment, the case has been described in which the operation mode is switched to the set-up mode when the set-up operator is pressed, but the present invention is not limited to this, and is executed even when the power is turned on. Alternatively, the correction signal may be changed by switching the operation mode at preset time intervals.

Further, in the above-described embodiment, the horizontal deflection circuit is driven to correct the deflection start timing and the deflection current, and the sub deflection yoke 18 and the video signal processing circuit 2 are driven to display the forward and backward display images. However, the present invention is not limited to this, and any one of these correction points may be corrected as necessary.

[0082]

As described above, according to the present invention, in the set-up mode, a cathode ray tube having an index pattern formed in the tube is driven by a predetermined test signal, and the light emission of this index pattern is detected and displayed. In the mode, by correcting the forward and backward display screens on the basis of this detection result, it is possible to prevent deterioration of image quality peculiar to the bidirectional deflection without deteriorating the image quality of the normal display image.

[Brief description of drawings]

FIG. 1 is a block diagram showing a display device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an index pattern.

FIG. 3 is a flowchart for explaining the operation of the correction circuit.

FIG. 4 is a schematic diagram showing an index pattern according to another embodiment.

FIG. 5 is a schematic diagram showing a display image when the phases are deviated on the outward path and the return path.

FIG. 6 is a schematic diagram showing a case where display images of a forward pass and a return pass are partially displaced.

[Explanation of symbols]

1 ... Display device, 2 ... Image signal processing circuit, 6 ... Driving circuit, 8 ... Cathode ray tube, 10 ... Horizontal deflection circuit, 12 ...
... horizontal deflection coil, 14 ... AFC circuit, 16 ... distortion correction circuit, 18 ... sub-deflection coil, 20 ... sub-DY drive circuit, 26 ... photo detector, 28 ... signal processing circuit, 32 ... correction circuit , 36 ... Central processing unit.

Claims (8)

[Claims] 1. A display device for forming a display image by supplying the deflection currents of the forward path and the backward path to a horizontal deflection coil so that a display image is formed by the deflection of the forward path and the backward path, respectively. Horizontal deflection circuit, a cathode ray tube in which an index pattern of a predetermined shape that emits light when a cathode ray is scanned is formed in the tube, a cathode ray tube drive circuit that drives the cathode ray tube based on a video signal, and the index pattern In the set-up mode, an index signal detection circuit that detects the emission of light and outputs an index signal is output, and in the set-up mode, a predetermined test signal is output to the cathode ray tube drive circuit to detect the index signal. Mode, with the result of the index signal detected in the set-up mode as the reference, A display image correction circuit that corrects the forward and backward display images so that the display image formed by the backward deflection and the display image formed by the backward deflection are matched. apparatus. 2. The display image correction circuit outputs a correction signal to the horizontal deflection circuit and corrects the deflection timing of the forward path and the backward path to obtain a display image formed by the forward path deflection and the display image. The display device according to claim 1, wherein the display images formed by the backward deflection are matched. 3. The display image correction circuit outputs a correction signal to the horizontal deflection circuit to correct the linearity of the deflection of the forward path and the backward path, thereby displaying the display image formed by the deflection of the forward path and the display image. The display device according to claim 1, wherein the display images formed by the backward deflection are matched. 4. The display image correction circuit outputs a correction signal to the cathode ray tube drive circuit, and outputs a drive signal to the cathode ray tube by the forward deflection and a drive signal to output to the cathode ray tube by the backward deflection. 4. The display image formed by the deflection of the forward path and the display image formed by the deflection of the return path are made to coincide with each other by correcting the signal, The claim 1, claim 2, or claim 3. Display device. 5. The horizontal deflection circuit comprises a correction transformer connected in series to the horizontal deflection coil,
5. The display device according to claim 3, wherein the correction transformer is driven based on the correction signal, and the deflection current of the horizontal deflection coil is corrected via the correction transformer. 6. The horizontal deflection circuit has a drive circuit for a sub deflection yoke that corrects a horizontal deflection magnetic field formed by the horizontal deflection coil, and drives the sub deflection yoke based on the correction signal. The display device according to claim 3, claim 4, or claim 5. 7. The display image correction circuit according to claim 1, wherein when the power is turned on, the operation mode is switched to the set-up mode for a predetermined period and then switched to the display mode. The display device according to claim 3, claim 4, claim 5, or claim 6. 8. The display image correction circuit switches an operation mode from the display mode to the set-up mode in response to the operation of a predetermined operator. Item 3, claim 4,
The display device according to claim 5, claim 6, or claim 7.