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Cathode-ray tube display device

A technology of cathode ray tube and display device, which is applied in the direction of cathode ray tube indicator, cathode ray tube/electron beam tube, electrode device and related components, etc., can solve the problems of obvious image noise and large image noise, etc.

Inactive Publication Date: 2004-12-22
MITSUBISHI ELECTRIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0013] However, in such a CRT display device, high brightness can be obtained on the one hand, but by increasing the sensitivity of the output current of the CRT corresponding to the driving voltage, even in the case of low-tone display, even if it is not obvious in the existing CRT display device Image noise also becomes larger, resulting in obvious disadvantages of image noise

Method used

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Examples

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Embodiment 1

[0027] figure 1 is a schematic configuration diagram of the CRT display device of Example 1. In this figure, for Figure 4 Structural units with the same function are given the same reference numerals, and their detailed descriptions are omitted. 1 is a CRT of MM tube, and CRT1 also includes an electron gun composed of a cathode 2 for emitting electrons, a first electrode G1, a second electrode G2, a third electrode G3, and an anode 3. In this figure, focusing electrodes and the like arranged after the third electrode G3 are also omitted for simplification of description.

[0028] The diameter of the electron through hole in the first electrode G1 and the electrode plate thickness of the electron through hole part, the diameter of the electron through hole in the second electrode G2 and the electrode plate thickness of the electron through hole part, the first electrode G1 and the second electrode The various parameters of the distance between G2 satisfy the following relat...

Embodiment 2

[0061] For example in figure 2 In the second image signal shown, the shift in signal level is large in the low-tone area where the signal level is suppressed compared with the first image signal, and in the boundary between the mid-tone and high-tone areas. When such a second image signal is used, the image will be displayed with a lowered tone due to the tone near the boundary. Since this boundary exists in a relatively low-tone area, there is a problem that the tone of particularly dark graphics (for example, night scenes) is significantly lowered in an image showing a lot of low-tone black.

[0062] In the second embodiment, this problem should be solved, and the sudden change of the signal level at the boundary between the signal level of the low tone area and the signal level of the high tone area in the second image signal output from the image signal modulation circuit 10 should be suppressed.

[0063] image 3 It is a diagram illustrating the operation of the image ...

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Abstract

In a CRT display device including a CRT (MM tube) having brightness higher than that in the background-art CRT, it is an object of the present invention to improve contrast and prevent conspicuous recognition of noises. A video signal modulation circuit (10) modulates a video signal (9) (first video signal) into a second video signal having a signal level in an area of low gradation level lower than a signal level of the first video signal. A cathode bias voltage source (7) generates a driving voltage on the basis of the second video signal. It is therefore possible to keep the driving voltage in the area of low gradation level low and reduce brightness in the area of low gradation level of a CRT (1). As a result, noises of an image in the area of low gradation level are not conspicuously recognized and a contrast value is increased, resulting in improvement in image quality.

Description

technical field [0001] The present invention relates to a CRT display device using a cathode ray tube. Background technique [0002] Figure 4 It is a schematic structural diagram of an existing general CRT display device. 1 is a CRT, and CRT1 includes, as shown in the figure, an electron gun composed of a cathode 2 for emitting electrons, a first electrode G1, a second electrode G2, a third electrode G3, an anode 3, and the like. The first electrode G1, the second electrode G2, and the third electrode G3 are cylindrical electrodes having electron passage holes disposed in the electron gun, and are used for extraction of electrons from the cathode 2, front focusing, and the like. In order to simplify the description, the focusing electrode and the like arranged after the third electrode G3 are omitted. Also, 4 is a flyback transformer (FBT), and 5 is a variable resistor. 6 is a video cathode amplifier for amplifying an image signal, 7 is a cathode bias voltage source for ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04N3/18G09G1/00G09G1/04G09G3/00H01J23/16H01J29/46H01J29/48H01J29/52H04N5/20H04N5/66H04N5/68H04N9/00
CPCH04N5/20H04N5/68H01J2229/4844H01J29/488H04N3/18
Inventor 中村芳知重松晴夫瓶子晃永安井裕信
Owner MITSUBISHI ELECTRIC CORP
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