JPH11252400A - Crt display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CRT display device which realizes reduction in the size and cost of a sensor through the use of a luminance sensor which is a single light sensor without using a two-dimensional light sensor. SOLUTION: The fluctuations of an external magnetic field affecting respective vertical, horizontal and rotational directions of a CRT screen is detected as an electrical signal by the variation in the screen luminance of a block displayed on the screen. Then an electrical signal cancelling the effects of magnetic field obtained based on this electric signal is added to an original vertical deflection current, horizontal deflection current and image rotation adjusting current to supply for a vertical deflection coil 1, a horizontal deflection coil 3 and an adjusting coil 5 for adjusting the rotation of the image to suppress the minute movement of the screen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a CRT display device which suppresses fine movement of a screen due to fluctuation of an external magnetic field.

[0002]

2. Description of the Related Art A conventional CRT display device produces a screen by electromagnetically deflecting an electron beam emitted from an electron gun and projecting it on a phosphor screen. This electromagnetic deflection is controlled by a magnetic field generated by a vertical deflection current output from a vertical deflection circuit and a horizontal deflection current output from a horizontal deflection circuit flowing through a vertical deflection coil and a horizontal deflection coil, respectively. This is done by deflecting in the horizontal and horizontal directions. The deflection amount of the electron beam controlled by the magnetic field is the magnetic field strength CRT length L
Is proportional to Therefore, particularly when the size of the CRT is increased, the influence of an external magnetic field applied from the outside increases, and in a situation where an AC magnetic field is generated around the display device, the screen slightly moves under the influence of the AC magnetic field.
In order to prevent this fine movement of the screen, the conventional display device covers the entire CRT with a magnetic shield plate to reduce the amount of an external magnetic field.

Further, as shown in FIG. 6, a conventional screen fine movement suppressing device for a CRT display device has a point display means 25 for displaying a point using an electron beam deflected by a vertical deflection coil 1 and a horizontal deflection coil 3; This point display means 25
A two-dimensional optical sensor 26 for detecting the movement of a point displayed on the CRT, and a vertical deflection coil 1 receiving a signal from the two-dimensional sensor light 26 so that the displayed point is stationary.
And a correction circuit 9 for applying a correction signal to the horizontal deflection coil 3.

Next, the operation of such a conventional screen fine movement suppressing device for a CRT display device will be described with reference to the drawings.

As shown in FIG. 6, the operation of the conventional screen fine movement suppressing device of a CRT display device is as follows. First, dots are displayed on the CRT screen by the point display means 26. CR
When the screen displayed on T is affected by an external magnetic field,
In response to this, the screen slightly moves, and the points displayed by the point display means 26 also slightly move by the external magnetic field.

Second, the fine movement of the point displayed by the point display means 26 is detected two-dimensionally by the two-dimensional optical sensor 27.

Third, a correction signal is mixed with the original deflection current and supplied to the vertical deflection coil 1 and the horizontal deflection coil 3 so that the point detected by the two-dimensional optical sensor 27 stops at one point. To suppress the fine movement of the screen.

As described above, the conventional device for suppressing fine movement of a screen of a CRT display device detects fine movement of a screen due to an external magnetic field using a two-dimensional optical sensor, and supplies a correction signal to a deflection coil to suppress the fine movement of the screen. .

[0009]

However, when a magnetic shield plate is used and when a screen fine movement suppressing device of a conventional CRT display device is used, a magnetic shield plate is used.
Since the CRT needs to be covered with the magnetic shield plate, there is a problem that the size of the entire display device is increased and the cost for the magnetic shield plate is high.

[0010] Further, since it is impossible to cover the front portion of the CRT, that is, the screen, with a magnetic shield plate,
There was a problem that the influence of the magnetic field in the tube axial direction could not be completely suppressed because the magnetic field in the tube axial direction could not be completely shielded. Further, as a third point, in the screen fine movement suppressing device of the conventional CRT display device, it is necessary to use a plurality of optical sensors to constitute a two-dimensional sensor in order to two-dimensionally detect the screen fine movement due to an external magnetic field, There has been a problem that the sensor cannot be reduced in size and cost.

Accordingly, an object of the present invention is to suppress the fine movement of the screen due to an external magnetic field without using a magnetic shield plate.
Provided is a CRT display device that realizes downsizing and cost reduction of a sensor by using a luminance sensor that is a single optical sensor without using a three-dimensional optical sensor.

[0012]

In order to solve the above-mentioned problems, a CRT display device according to a first aspect of the present invention electromagnetically deflects an electron beam emitted from an electron gun by a vertical deflection coil and a horizontal deflection coil, and emits a fluorescent light. A CRT that projects an image on a surface to display an image, a vertical current generation circuit that supplies a vertical deflection current to a vertical deflection coil of the CRT, a horizontal current generation circuit that supplies a horizontal deflection current to the horizontal deflection coil, An adjustment coil for adjusting the rotation of the image, an adjustment current generating circuit for supplying an adjustment current to the adjustment coil, and a block for displaying the image on a predetermined block at a predetermined position on the phosphor screen A display circuit and a block display circuit for detecting a change in luminance caused by a fine movement due to an external magnetic field fluctuation of a block displayed on the CRT. A vertical deflection coil, the horizontal deflection coil, and the adjustment coil so that a change in luminance due to an external magnetic field variation of the block displayed by receiving the electrical signal from the conversion means is eliminated. And a correction circuit that supplies a correction signal to the vertical deflection coil, the horizontal deflection coil, and the adjustment coil. Is characterized by suppressing image fine movement due to

A CRT display device according to a second aspect of the present invention provides a CRT for displaying an image by electromagnetically deflecting an electron beam emitted from an electron gun by a vertical deflection coil and a horizontal deflection coil, and projecting the image on a phosphor screen. A pair of vertical magnetic field canceling coils installed on an upper side and a lower side;
A pair of horizontal magnetic field canceling coils installed on the right and left sides of the RT, a tube axial magnetic field canceling coil installed before and after the CRT, and a block display for displaying the image on a predetermined block at a predetermined position on the phosphor screen. A conversion circuit for detecting a change in luminance caused by a fine movement due to an external magnetic field fluctuation of the block displayed on the CRT by the block display circuit, and converting the change into an electric signal; and converting the electric signal from the conversion means into an electric signal. The vertical magnetic field canceling coil, the horizontal magnetic field canceling coil, and a correction circuit for providing a correction signal to the tube axis direction canceling coil so that a change in luminance due to an external magnetic field variation of the received and displayed block is eliminated, The conversion into a magnetic field canceling coil, the horizontal magnetic field canceling coil, and the tube axial direction magnetic field canceling coil By electric signals output from the stage to supply an electric signal is minimized, which comprises suppressing the screen fine movement due to external magnetic field fluctuations.

[0014]

Next, a CRT display device according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a C-type memory device according to a first embodiment of the present invention.
FIG. 3 is a block diagram of an RT display device.

FIG. 2 is a circuit diagram of a C according to a first embodiment of the present invention.
FIG. 3 is a configuration diagram of a screen luminance sensor of the RT display device.

FIG. 3 is a circuit diagram of a first embodiment of the present invention.
FIG. 4 is a waveform diagram of an electric signal and an external magnetic field in each block of the RT display device.

As shown in FIG. 1, the CRT display device according to the first embodiment of the present invention comprises a vertical current generating circuit 2 for supplying a vertical deflection current to a vertical deflection coil 1 arranged at the neck of a CRT 22; A horizontal current generating circuit 4 for supplying a horizontal deflection current to the horizontal deflection coil 3 arranged at the neck of the CRT 22, and an adjustment for supplying an adjustment current for adjusting the rotation of the screen to the adjustment coil 5 arranged at the funnel of the CRT. A current generating circuit 6, a block display circuit 7 for displaying an image on a predetermined block at a predetermined position on the phosphor screen, and a fine movement of the screen due to a change in an external magnetic field of the block displayed on the CRT by the block display circuit 7. Two screen brightness sensors 8 for detecting a change in brightness that occurs and converting the brightness into an electric signal, and an electric signal from the screen brightness sensor 8 and a vertical current generation circuit 2 Vertical deflection period signal receiving, adjustment coil 5 and the vertical deflection coil 1 and the horizontal deflection coils 3 so that the change in luminance is minimized by the fine movement of the displayed block
A correction circuit 9 for supplying a correction signal to the vertical deflection amplifier 19 for mixing and amplifying the correction signal output from the correction circuit 9 with a vertical deflection current; mixing a correction signal output from the correction circuit 9 with a horizontal deflection current; A horizontal deflection amplifier 20 for amplification;
Mixing the correction signal output from the correction circuit 9 with the adjustment current,
And an adjustment current amplifier 21 for amplification.

The block display circuit 7 has a CRT 22
The image memory 10 stores data for displaying a block at a specific location in the display area of the image display device, and a display circuit 11 for displaying the image data on the CRT 22. Here, the blocks are displayed in a size corresponding to the luminance detection area of the screen luminance sensor 8.

The screen brightness sensor 8 detects the screen brightness and converts it into an electric signal. For example, a photodiode is used. As shown in the example of FIG. 2A, the brightness of the screen brightness sensor 8 is reduced by the movement of the block displayed by the block display circuit 7 due to an external magnetic field fluctuation. This is detected and converted into an electric signal.

In addition, the correction circuit 9 includes a screen brightness sensor 8
A conversion circuit 12 for converting the electric signal output from the controller and the vertical deflection period signal from the vertical current generation circuit 2 into a correction signal;
Phase adjustment circuits 13, 14, 15 for adjusting the phase of the signal
And amplifiers 16, 17, and 18.

Next, the CR according to the first embodiment of the present invention will be described.
The operation of the T display device will be described with reference to the drawings.

The operation of the CRT display device according to the first embodiment of the present invention is as follows. First, as shown in FIGS.
Display blocks at various locations. The display position is, for example, as shown in FIG.
As shown in (b), these are the diagonally opposite ends of the CRT display area that is invisible to the user. The displayed block is shown in FIG.
In response to the influence of the external magnetic field having the waveform shown in FIG. The period at which the external magnetic field radiated by the electric equipment becomes a problem is the power frequency (50, 60H).
z), and in this case, the fine movement of the screen finely moves at a period obtained by subtracting the external magnetic field period from the vertical deflection period.

Second, the luminance of the two blocks displayed by the display circuit 7 by the two screen luminance sensors 8 is converted into an electric signal and detected. At this time, the block displayed on the screen is slightly moved by an external magnetic field, and a luminance change due to the moving amount of the block is detected by the screen luminance sensor 8, so that the electric signal output from the screen luminance sensor 8 is finely moved ( It fluctuates as shown in FIG. 3C according to FIG.

Third, one of the electric signals output from the two screen luminance sensors 8 is converted into one by the conversion circuit 12.
Inversion is performed for each cycle, and the cycle is converted into a cycle obtained by subtracting the screen brightness fluctuation cycle from the vertical deflection cycle, and output as shown in FIG.

Fourth, the electric signal output from the conversion circuit 12 is supplied to the vertical deflection amplifier 19 through the phase adjustment circuit 13 and the amplifier 16 and mixed with the vertical period sawtooth signal supplied from the vertical current generation circuit 2. I do. Also, conversion circuit 1
2 is supplied to the horizontal deflection amplifier circuit 20 through the phase adjustment circuit 14 and the amplifier 17 and mixed with the horizontal period sawtooth signal supplied from the horizontal current generation circuit 4. Further, the electric signal output from the conversion circuit 12 is supplied to the adjustment current amplification circuit 21 through the phase adjustment circuit 15 and the amplification circuit 18 and mixed with the adjustment current supplied from the adjustment current generation circuit 6. This mixed wave is output to the vertical deflection coil 1, the horizontal deflection coil 3, and the adjustment coil 5, respectively.
The phases are adjusted by the phase adjustment circuits 13, 14, 15 and the amplitudes are adjusted by the amplifiers 16, 17, 18 so that the changes in the outputs of the two screen luminance sensors 8 are both minimized. On this occasion,
Assuming that the external magnetic field has the waveform shown in FIG. 3A, the vertical correction signal supplied to the vertical deflection coil 1 is as shown in FIG. 3E, and the horizontal correction signal supplied to the horizontal deflection coil is FIG. (F), and the rotation correction signal supplied to the adjustment coil 5 is as shown in FIG. These waveforms are obtained by changing the polarity and level of the waveform of the external magnetic field shown in FIG.

The current waveforms shown in FIGS. 3 (e), 3 (f) and 3 (g) are supplied to the vertical deflection coil 1, the horizontal deflection coil 3 and the adjustment coil 5, respectively, so that the electron beams in the vertical, horizontal and rotational directions can be obtained. Since the deflection is corrected, fine movement of the screen is suppressed.

Therefore, with the above-described configuration, it is possible to suppress fine movements in the vertical, horizontal, and rotational directions of the screen.

Next, the CR according to the second embodiment of the present invention will be described.
The T display device will be described with reference to the drawings.

FIG. 4 is a circuit diagram of a C according to a second embodiment of the present invention.
FIG. 3 is a block diagram of an RT display device.

FIG. 5 is a circuit diagram of a second embodiment of the present invention.
FIG. 3 is a waveform diagram of an electric signal supplied to each cancel coil of the RT display device and an external magnetic field.

Next, the CR according to the second embodiment of the present invention will be described.
The operation of the T display device will be described with reference to the drawings.

As shown in the second embodiment in FIG. 4, the electric signal output from the conversion circuit 12 is supplied to the horizontal magnetic field canceling coil 23 through the phase adjustment circuit 13 and the amplifier 16. The electric signal output from the conversion circuit 12 is passed through the phase adjustment circuit 14 and the amplifier 17 to
It is supplied to the vertical magnetic field canceling coil 23. Further, the electric signal output from the conversion circuit 12 is
5, through the amplifier 18 and to the tube axial magnetic field canceling coil 25. Here, the phase adjustment circuit 1 is designed so that the changes in the outputs of the two screen luminance sensors 8 are both minimized.
The phases are adjusted by 3, 14, and 15, and the amplitude is adjusted by the amplifiers 16, 17, and 18. At this time, assuming that the external magnetic field has a waveform shown in FIG. 5A, the correction signal supplied to the horizontal magnetic field canceling coil 18 becomes as shown in FIG. The signal is shown in FIG.
5C, and the correction signal supplied to the tube axis direction magnetic field canceling coil 25 is as shown in FIG. 5D. These waveforms are obtained by changing the polarity and level of the waveform of the external magnetic field shown in FIG.

The current waveforms shown in FIGS. 5B, 5C and 5D are respectively a horizontal magnetic field canceling coil 23, a vertical magnetic field canceling coil 24, and a tube axial magnetic field canceling coil 25.
Is supplied, the deflection of the electron beam in the vertical, horizontal, and rotational directions is corrected, so that the fine movement of the screen is suppressed.

Therefore, with the above-described configuration, it is possible to suppress fine movement in the vertical, horizontal, and rotational directions of the screen.

[0036]

As described above, according to the CRT display of the present invention, there is provided a sensor for detecting a change in screen brightness due to an external magnetic field applied from the outside, so that the signal output from this sensor does not fluctuate. To a deflection coil that deflects the electron beam in the vertical and horizontal directions of the screen, an adjustment coil together with a cancel coil that cancels the external magnetic field in the vertical and vertical directions, or to a cancel coil that cancels the external magnetic field in the tube axis direction. Since the correction electric signal is configured to be supplied, vertical, horizontal, and fine rotation of the screen due to an external magnetic field can be suppressed without using a magnetic shield plate.

Further, according to the CRT display of the present invention, there is an effect that the influence of an external magnetic field in the direction of the tube axis of the CRT, which was incomplete by using the magnetic shield plate, can be suppressed. Further, as a third point, since the sensor for detecting the fine movement of the screen is not a two-dimensional sensor but a single brightness sensor, there is an effect that the sensor can be reduced in size and cost.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of a screen luminance sensor of the CRT display device according to the first embodiment of the present invention.

FIG. 3 is a waveform diagram of an electric signal and an external magnetic field in each block of the CRT display device according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a CRT display device according to a second embodiment of the present invention.

FIG. 5 is a waveform diagram of an electric signal and an external magnetic field supplied to each cancel coil of the CRT display device according to the second embodiment of the present invention.

FIG. 6 is a block diagram of a conventional CRT display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vertical deflection coil 2 Vertical current generation circuit 3 Horizontal deflection coil 4 Horizontal current generation circuit 5 Adjustment coil 6 Adjustment current generation circuit 7 Block display circuit 8 Screen luminance sensor 9 Correction circuit 10 Image memory 11 Display circuit 12 Conversion circuit 13, 14, Reference Signs List 15 phase adjustment circuit 16, 17, 18 amplifier 19 vertical deflection amplifier 20 horizontal deflection amplifier 21 adjustment current amplifier 22 CRT 23 horizontal magnetic field cancel coil 24 vertical magnetic field cancel coil 25 tube axis magnetic field cancel coil 26 point display means 27 two-dimensional optical sensor 28 display blocks

Claims (2)

[Claims] An electron beam emitted from an electron gun is electromagnetically deflected by a vertical deflection coil and a horizontal deflection coil, and is projected on a phosphor screen to display an image.
A vertical current generation circuit for supplying a vertical deflection current to the vertical deflection coil of T; a horizontal current generation circuit for supplying a horizontal deflection current to the horizontal deflection coil; and adjusting the rotation of the image arranged in the funnel section of the CRT Adjusting coil
An adjustment current generating circuit for supplying an adjustment current to the adjustment coil; a block display circuit for displaying the image on a predetermined block at a predetermined position on the phosphor screen; and a block display circuit for displaying the image on the CRT by the block display circuit. A conversion means for detecting a change in luminance caused by a fine movement due to an external magnetic field fluctuation and converting it into an electric signal, and receiving the electric signal from the conversion means so that the change in luminance due to the external magnetic field fluctuation of the displayed block is eliminated. And a correction circuit for providing a correction signal to the vertical deflection coil, the horizontal deflection coil, and the adjustment coil, and an electric signal output from the conversion unit to the vertical deflection coil, the horizontal deflection coil, and the adjustment coil. A CRT display characterized by suppressing an image micro-movement due to a fluctuation of an external magnetic field by supplying an electric signal which is minimized. Apparatus. 2. A CRT for displaying an image by electromagnetically deflecting an electron beam emitted from an electron gun by a vertical deflection coil and a horizontal deflection coil, and projecting the image on a phosphor screen.
A pair of vertical magnetic field canceling coils installed above and below T; a pair of horizontal magnetic field canceling coils installed on the right and left sides of the CRT; and a tube axial magnetic field canceling coil installed before and after the CRT. A block display circuit for displaying the image on a predetermined block at a predetermined position on the phosphor screen, and the block display circuit detecting a change in luminance caused by a fine movement due to an external magnetic field change of the block displayed on the CRT. Converting means for converting the vertical magnetic field canceling coil, the horizontal magnetic field canceling coil and the horizontal magnetic field canceling coil so as to eliminate the change in luminance due to the external magnetic field fluctuation of the block displayed by receiving the electric signal from the converting means. A correction circuit for providing a correction signal to the tube axis direction cancellation coil, wherein the vertical magnetic field cancellation coil and the horizontal A CRT display device characterized in that by supplying an electric signal that minimizes an electric signal output from the conversion means to a magnetic field canceling coil and the tube axis direction magnetic field canceling coil, screen fine movement due to an external magnetic field fluctuation is suppressed. .