JPH05130627A - Display device - Google Patents

Abstract

PURPOSE:To enable confirming demagnetizing operation executing status by executing the uniform monochromatic display of an image on a whole screen or an effective display screen displayed on a display device using a color cathode-ray tube(CRT) and a demagnetizing coil during the execution period of the demagnetizing operation. CONSTITUTION:When a manual demagnetizing switch 5 is turned on, an one-shot multivibrator circuit 6 connected to the switch 5 is started to generate a relay driving signal for a time necessary for demagnetizing operation, a relay 10 is made conductive through a driving circuit 9 for the relay 10 and current is allowed to flow into the demagnetizing coil 3 connected to a positive characteristic thermistor 4 in series to execute demagnetizing operation. On the other hand, the period of a demagnetizing signal formed by the circuit 6 is extended by a timer circuit 7, a monochromatic chrominance signal is formed by a monochromatic display part 8 and supplied to an image amplifier circuit 1 to attain uniform monochromatic display on the whole screen of the CRT 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device such as a computer display.

[0002]

2. Description of the Related Art In a television or a computer display using a cathode ray tube, a positive temperature coefficient thermistor or the like is used for a degaussing coil provided around the cathode ray tube in order to prevent a landing deviation due to magnetization of a shadow mask due to geomagnetism. Thus, a degaussing current, which decays with time when the power of the device is turned on, is supplied for degaussing, or an independent degaussing switch is provided to degauss as necessary.

FIG. 2 is a block diagram of a conventional display device.
Is an image amplifier circuit, 2 is a display cathode ray tube, 3 is a degaussing coil, 4 is a positive temperature coefficient thermistor, and 5 is a manual degaussing switch. Hereinafter, a conventional display device will be described with reference to FIG.
A positive temperature coefficient thermistor 4 and a degaussing coil 3 provided around the cathode ray tube 2 are connected in series and connected to a power supply circuit (not shown) so that the degaussing switch 5 is turned on when the device is turned on. Alternatively, degaussing is performed by turning on the degaussing switch 5 as needed to pass a degaussing current that decays with time. At this time, the display of the cathode ray tube 2 is an image corresponding to the signal input from the image input.

[0004]

However, in the above-mentioned conventional configuration, since the degaussing operation is carried out while the image is normally displayed with, for example, sentences, the display screen is not constant, and the degaussing operation is carried out with certainty. It is difficult to confirm whether the uneven color due to the magnetization of the mask has been eliminated. In particular, when the degaussing current is controlled manually by using a positive temperature coefficient thermistor and the degaussing operation is manually performed, if the degaussing time is short, not only degaussing is insufficient, but conversely magnetizing may occur.

In order to solve the above-mentioned problems, the present invention provides a display device which has good operability and can confirm a good display state.

[0006]

In order to solve the above problems, the present invention includes a circuit for supplying a degaussing current to a degaussing coil for a certain period of time so that the image display is a uniform monochromatic display color on the entire screen or the effective screen. It is a thing.

[0007]

According to the present invention, with the above-described structure, the display can be a single color uniform over the entire screen when the degaussing operation is performed.

[0008]

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

FIG. 1 is a block diagram of a display device according to an embodiment of the present invention. 1 is a video amplifier circuit, 2 is a display cathode ray tube, 3 is a degaussing coil, 4 is a positive characteristic thermistor, and 5 is a manual degaussing switch. Since these have the same configuration as the conventional example, the same reference numerals are used. 6 is a one-shot multivibrator circuit that sets the degaussing time and the time for which the image is displayed in a uniform single color, and 7 is an output signal from the one-shot multivibrator circuit 6, which makes the image display after the degaussing a uniform single color. A reference numeral 8 is a timer circuit for setting the time to be turned on, 8 is a monochromatic display section for outputting a color signal which receives the output of the timer circuit 7 and makes the image display uniform, to the video amplifier circuit 1, and 9 is a drive circuit for the relay 10.

A display device according to an embodiment of the present invention will be described below. Manual degaussing switch 5 in FIG.
Is turned on, the one-shot multivibrator circuit 6 connected thereto is activated to generate a relay drive signal for the time required for the degaussing operation. Relay 10 with this signal
Then, the relay 10 is turned on through the drive circuit 9 and the current is passed through the positive temperature coefficient thermistor 4 and the degaussing coil 3 connected in series with the thermistor 4 to perform the degaussing operation. The relay drive signal created by this one-shot multivibrator circuit 6 is
The output time is extended by the time set by the timer circuit 7, and a color signal uniform over the entire screen is output from the monochromatic display unit 8 for a time corresponding to the output signal from the timer circuit 7.
Output to the CRT with a uniform color on the entire screen.
By confirming that the degaussing operation is completed by confirming the color unevenness on the screen during the degaussing operation and after the degaussing operation is completed, and by confirming the residual color unevenness due to the magnetization of the shadow mask. Is possible. When the color displayed on the cathode ray tube is white and color unevenness occurs, it is possible to make the confirmation easier by mixing other colors with white.

In this embodiment, the description has been made by using the relay, but it is constituted by an electronic circuit using a triac or the like,
It is also clear that the same effect can be obtained even if the demagnetizing current is obtained by using the self-resonant current without using the positive temperature coefficient thermistor.

[0012]

As described above, according to the present invention, when the degaussing operation is performed due to the color deviation of the cathode ray tube during use, the status of the degaussing operation can be confirmed, so that a good degaussing state can always be obtained. It is possible to provide a display device capable of

[Brief description of drawings]

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

FIG. 2 is a block diagram of a conventional display device.

[Explanation of symbols]

 1 Image amplification circuit 2 CRT 3 Degaussing coil 4 Positive characteristic thermistor 5 Manual degaussing switch 6 One-shot multivibrator circuit 7 Timer circuit 8 Single color display 9 Drive circuit 10 Relay

Claims (3)

[Claims] 1. A color display device having a cathode ray tube and a degaussing coil for performing a degaussing operation by passing a degaussing current through the degaussing coil, wherein an image displayed on the cathode ray tube is made uniform for a period of time during which the degaussing operation is performed. A display device comprising a monochromatic display unit for monochromatic display. 2. The display device according to claim 1, wherein the monochrome display color is white. 3. The display device according to claim 1, further comprising a timer circuit for setting a display time of a single color display signal.