JPH10304391A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device that corrects a color automatically in the case a cathode ray tube(CRT) and a shield case are magnetized locally with an external magnetic field. SOLUTION: A magnetism sensor 1 detects a direction and a strength of an external magnetic field 101, and a main correction coil control circuit 3 drives a main correction coil 7 based on data in a ROM 3a in response to the detection to generate a magnetic field that cancels the external magnetic field 101. On the other hand, a display control circuit 4 displays a prescribed display color for detecting a color sensor 8 on a screen of a CRT 5. When there is no effect by an external magnetic field, the display color is correct and no correction by a sub correction coil is made. In case that the display color is changed due to the effect of an external magnetic field, the color sensor 8 detects the display color and a sub correction coil control circuit 2 drives the sub correction coil 6 in response to the detection to generate a magnetic field so that the display color is a prescribed display color.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube (CRT).
The present invention relates to a display device, and particularly to a magnetic correction function incorporated in a color CRT display to correct the influence of a magnetic field change outside the display on quality such as color purity.

[0002]

2. Description of the Related Art Conventionally, this type of display device with a magnetic correction function is disclosed in, for example, Japanese Patent Application Laid-Open Nos. 60-118879, 62-104391 and 62-104392.
As shown in the publication, a change in an external magnetic field is detected by a magnetic sensor, and a correction coil is driven by the detected value,
Magnetic correction has been performed by canceling the amount of change in the external magnetic field by the magnetic field generated by the correction coil.

FIG. 3 is a configuration diagram of an example of a conventional display device with a magnetic correction function. The magnetic sensor 1 has an external magnetic field 10
1 is detected, and a magnetic sensor output 102 is output to the main correction coil control circuit 3. The main correction coil control circuit 3 reads data from a built-in ROM or the like based on the magnetic sensor output 102, outputs a main correction coil drive signal 104 based on the data, and drives the main correction coil 7 provided on the CRT 5. The main correction coil 7 receives the main correction coil drive signal 104, generates a magnetic field that cancels the external magnetic field 101, and corrects the trajectory of the electron beam of the CRT 5.
It should be noted that although shown collectively in FIG. 3, usually, there are three similar magnetic sensors for detecting magnetic fields in three orthogonal directions, and three main correction coils for canceling the magnetic fields.

[0004] For example, Japanese Patent Application Laid-Open No. 57-212492 discloses a system in which a plurality of magnetic correction coils are used and manual adjustment is performed visually. FIG. 4 is a configuration diagram of an example of a display device with a magnetic correction function according to the above-mentioned Japanese Patent Application Laid-Open No. 57-212492. The sub correction coil control circuit 2 receives the manual adjustment 107 by visual observation, outputs a plurality of sub correction coil drive signals 105, and
Drive. The plurality of sub-correction coils 6 are separately driven,
Optimal correction is performed for each display part of the CRT 5. The adjuster adjusts the sub-correction coil control circuit 2 while visually checking the display screen, so that the CRT 5 by the external magnetic field 101 can be adjusted.
To correct display distortion and color misregistration. Further, the optimum correction value is stored in the sub correction coil control circuit 2.

[0005]

Among the conventional techniques described above, the problem with the method of detecting and correcting a magnetic field by a magnetic sensor (FIG. 3) is that a CRT or a shield case is locally attached by an external magnetic field. In the case of magnetizing, sufficient magnetic correction may not be performed simply by detecting the external magnetic field and uniformly canceling it. Such a state is particularly likely to occur at a screen edge in a display device having a large magnetic field change and a large screen.

FIG. 5 shows an example of a display screen when correction is performed by the method shown in FIG. FIG. 5A shows a display screen before the application of a magnetic field (an example of a solid green display). FIG. 5B shows a display screen before correction when a magnetic field is applied perpendicularly to the screen. FIG. 5C shows an example of a display screen in a case where the correction is performed by the method of FIG. 3 but the color misregistration cannot be completely corrected due to local magnetization.

In FIG. 5C, since local magnetization occurs at the corner of the screen, the corner of the screen does not return to the state before the application of the magnetic field as shown in FIG. I have. However, this color shift cannot be corrected in the method of FIG. 3 because local correction is difficult.

The problem with the manual correction method (FIG. 4) described above is that since the correction is made visually and manually, the method is not applicable to moving objects such as ships and vehicles in which the external magnetic field changes continuously. That is not possible.

Accordingly, an object of the present invention is to provide a display device with a color correction function capable of performing a display with higher display quality by correcting a color shift caused by local magnetization caused by an external magnetic field. To provide.

[0010]

According to the present invention, in order to achieve the above object, a display control means for displaying a predetermined color at a predetermined position on a screen of a cathode ray tube, and a display control means for displaying a predetermined color at a predetermined position on the screen. Color detection means for detecting a color, first coil means for correcting the trajectory of the electron beam of the cathode ray tube,
And first coil control means for providing a drive signal to the first coil means in response to detection by the color detection means.

Further, in the present invention, a magnetic detecting means for detecting an external magnetic field of the cathode ray tube, a second coil means for correcting a trajectory of an electron beam of the cathode ray tube, And a second coil control means for supplying a drive signal to the second coil means.

In the present invention, the display control means displays the predetermined color at a plurality of predetermined positions on the screen, and a plurality of the first coil means are provided. A drive signal may be given to each of the first coil means so that the color displayed at the plurality of predetermined positions becomes the predetermined color.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment of the present invention. In FIG. 1, a magnetic sensor 1 detects the direction and strength of an external magnetic field 101 and outputs a magnetic sensor output 10 to a main correction coil control circuit 3.
2 is output. The main correction coil control circuit 3 reads data from the built-in ROM 3a based on the magnetic sensor output 102, outputs a main correction coil drive signal 104 based on this data, and drives the main correction coil 7 provided on the CRT 5. The main correction coil 7 receives the correction coil drive signal 104, generates a magnetic field that cancels the external magnetic field 101,
The trajectory of the electron beam of RT5 is corrected.

On the other hand, the plurality of color sensors 8 detect color misregistrations at a plurality of specific positions on the screen of the CRT 5 and output color sensor outputs 106 to the sub correction coil control circuit 2 respectively. The sub correction coil control circuit 2 receives the color sensor output 108 and drives a plurality of sub correction coils 6 provided on the CRT 5. Each color sensor 8 and each sub-correction coil 6 are arranged in one-to-one correspondence. The color sensor 8, the sub correction coil control circuit 2 and the sub correction coil 6 constitute a feedback system. In this embodiment, two color sensors 6 and two sub-correction coils 6 are provided. However, it is obvious that the number increases in accordance with the required quality of the display screen.

The display control circuit 4 includes a display video signal 10.
3 is displayed on the CRT 5. In addition, a display for color sensor detection is also performed.

Next, the operation of the circuit of FIG. 1 will be described.
The operations of the magnetic sensor 1, the main correction coil control circuit 3, the main correction coil 7, and the CRT 5 when the external magnetic field 101 changes are the same as those in FIG. At each position on the CRT 5 screen corresponding to the mounting position of the color sensor 8, a predetermined display color for detecting the color sensor 8 is displayed in advance by the display control circuit 4.

FIG. 2 shows a display example of a display color for detecting the color sensor 8 on the CRT screen. In this display example, the display portion 108 for the color sensor is provided at the four corners which are usually considered to be most easily magnetized with respect to the normal display region 109, but depending on the characteristics of the display device and the quality of the display screen required. These numbers and positions may be changed as needed, and the number of color sensor display portions 108 is required as many as the number of attached color sensors 8. In addition, since the edge of the screen of the CRT 5 is actually covered with a bezel or the like, the color sensor display portion 108 and the color sensor 8 cannot be seen from the front.

The display control circuit 4 performs a normal display using the display video signal 103 in the normal display area 109,
The display color for detecting the color sensor 8 is displayed in the color sensor display portion 108. When there is no influence of the magnetization by the external magnetic field 101, the display color of the display portion 108 for the color sensor becomes the above-mentioned predetermined display color (hereinafter, referred to as a correct display color), and the correction by the sub correction coil 6 is not performed.

When the display color changes due to the influence of the magnetization of the external magnetic field 101, the color sensor 8 sets the display location 108
And outputs the color sensor output 106 to the sub correction coil control circuit 2. The sub correction coil control circuit 2 outputs the sub correction coil drive signal 105 to drive the sub correction coil 6. The auxiliary correction coil 6 outputs a correction coil drive signal 105
In response, a magnetic field is generated so that the display color at the mounting position becomes the correct display color. The above operation is automatically repeated until the display color of the color sensor display portion 108 becomes a correct display color.

[0020]

As described above, according to the present invention,
By detecting the color displayed at a predetermined position on the screen and driving the first coil means such as the sub-correction coil, the color shift caused by local magnetization of the cathode ray tube based on an external magnetic field or the like can be prevented. It can be automatically and effectively removed.

In addition, since the second coil means such as the main correction coil is driven by detecting the external magnetic field, the local correction is automatically performed by the second coil means while the local correction is automatically performed. Color correction can be performed automatically.

Further, by correcting the color misregistration at a plurality of portions of the screen, it is possible to perform color correction at four corners of the screen, which is likely to occur in a large screen, for example.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a display example of a CRT screen.

FIG. 3 is a block diagram illustrating an example of a conventional display device.

FIG. 4 is a block diagram showing another example of a conventional display device.

FIG. 5 is a configuration diagram showing an example of a display screen before applying a magnetic field, an example of a display screen after applying a magnetic field in a direction perpendicular to the screen, and an example of a display screen when correction is performed in a conventional display device.

[Description of Signs] 1 Magnetic sensor 2 Sub correction coil control circuit 3 Main correction coil control circuit 4 Display control circuit 5 CRT 6 Sub correction coil 7 Main correction coil 8 Color sensor 101 External magnetic field 102 Magnetic sensor output 103 Display video signal 104 Main correction coil drive signal 105 Sub correction coil drive signal 106 Color sensor output 108 Display location for color sensor

Claims (3)

[Claims] 1. A display control means for displaying a predetermined color at a predetermined position on a screen of a cathode ray tube, a color detection means for detecting a color displayed at a predetermined position on the screen, and a trajectory of an electron beam of the cathode ray tube A display device comprising: a first coil unit that corrects a color difference; and a first coil control unit that supplies a drive signal to the first coil unit in response to detection of the color detection unit. 2. A magnetic detecting means for detecting an external magnetic field of the cathode ray tube; a second coil means for correcting an electron beam trajectory of the cathode ray tube; 2. The display device according to claim 1, further comprising a second coil control unit that supplies a drive signal to the coil unit. 3. The display control means displays the predetermined color at a plurality of predetermined positions on the screen,
A plurality of coil means, wherein the first coil control means supplies a drive signal to each of the first coil means so that the color displayed at the plurality of predetermined positions becomes the predetermined color. The display device according to claim 1.