JPS61151591A - Display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a display device used in an image processing terminal or the like as an ultra-high-definition image display using an anode ray tube.

[Technical background of the invention and in between! Point i] Recently, with the advent of office automation (OA), vapor-less systems are progressing, and large-capacity image file devices and the like are being put into practical use. Therefore, various types of image processing are being performed on the screens of display devices using cathode ray tubes. However, conventional display devices of this type have a small number of scanning lines and insufficient resolution. For example, high resolution data obtained by optically scanning an A4 size document at a scanning density of about 8 lines/a1 cannot be displayed as is. In other words, in order to display high-resolution data obtained by scanning an A4-sized document at a scanning density of approximately 8 lines/sl on a cathode ray tube without flickering, the number of effective scanning lines and number of effective horizontal dots must be 2400. is 1
792 or more are required (when displayed vertically)
. And in order to display the above ^resolution screen,
A cathode ray tube with a large display screen of 1 inch to 20 inches is required. Cathode ray tubes with such large display screens have traditionally been very difficult to see due to the roundness of the phosphor screen, and ceiling lights are reflected on the screen, causing eye fatigue. Recently, cathode ray tubes with flat, rectangular screens have been developed. However, when attempting to display the above-mentioned high-resolution data at high resolution using this planar cathode ray tube, the following problems occur, making it impossible to obtain a satisfactory image.

FIG. 2 shows the operation of a general flat cathode ray tube.

Electrons fly out from the cathode 2 heated by the heater 1, are controlled by the control electrode 3, and are further accelerated by the acceleration electrode 4, hitting the fluorescent screen 5 on the tube surface. On the way, an electron lens 6 is configured for the electron beam B using a focusing means such as a focus electrode, and focusing is performed at an imaging point O. Further, the electron beam B is deflected from the deflection center P by the vertical deflection coil and the horizontal deflection coil, and a display screen is formed by this scanning. However, as shown in FIG. 2, the imaging position Q of the electron beam B after being deflected from the deflection center P is on the radius from the deflection center P to the imaging point 0, and the phosphor screen 5 is In the case of a flat surface, the amount of defocus increases with deflection. Furthermore, since the current flowing through the deflection coil is proportional to the deflection angle, as the deflection angle increases, the distance from the deflection center P to the phosphor screen 5 increases.
The position with the largest deflection angle from the deflection center P is a square on the diagonal line. For this reason, in a display device using a flat cathode ray tube, pincushion-like distortion occurs as shown by the broken line in Figure 3, and at the same time, even when a linear deflection current is applied, the image changes from the center to the periphery of the screen. It gets longer. Further, orthogonal distortion due to the orthogonality of the vertical deflection coil and the horizontal deflection coil cannot be ignored, as shown by the broken line in FIG. 4.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and its object is to provide a display device that can particularly display high-resolution data in a high-definition and easy-to-see manner.

[Summary of the Invention] In order to achieve the above object, the present invention provides distortion correction that corrects defocus and various distortions caused by flat cathode ray tubes with particularly large display screens in accordance with the scanning coordinate position of a scanning electron beam. By providing the means, various distortions can be sufficiently removed.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 11 denotes a flat cathode ray tube, which is equipped with a horizontal deflection coil 12, a vertical deflection coil 13, and a dynamic focus coil 14.

The horizontal deflection signal It is supplied to the horizontal deflection driver 16 along with the output of. Further, the multiplier 18 is supplied with the output of a multiplier 21, which will be described later. The horizontal deflection driver 16 adds the three input signals and drives the horizontal deflection coil 12 according to the added signal. Further, the vertical deflection signal Y is supplied to the vertical deflection driver 20 via the linearity distortion correction circuit 19 and also supplied to multipliers 21 and 22, respectively, and the output of this multiplier 22 is supplied to the vertical deflection driver 20. Supplied. Further, the output of the multiplier 17 is supplied to the multiplier 22 . The vertical deflection driver 20 adds the two input signals and drives the vertical deflection coil 13 according to the added signal. Also,
The vertical deflection signal Y is supplied to an inverting amplifier 23. A variable resistor 24 is connected between the output end and the input end of the inverting amplifier 23.

Roughly speaking, each output of the multipliers 17 and 21 is supplied to an adder 25, and the output of this adder 25 is supplied to a dynamic focus driver 26. This dynamic focus driver 26 drives the dynamic focus coil 14.

With this configuration, the output of the multiplier 17 is
2. The output of multiplier 21 is Y2, and the output of multiplier 18 is -K.
The output of IXY2 and the multiplier 22 becomes -2X''Y, and the output of the adder 25 becomes LL- (ktX''+2Y2), so that the outputs necessary for correction can be obtained. In addition, K
l, K2, kt.

k2 is a constant. Therefore, horizontal deflection driver 16
A correction current can be applied to the horizontal deflection coil 12 via the horizontal deflection coil 12 . Similarly, a correction current can be applied to the vertical deflection coil 13 via the vertical deflection driver 20. Further, a correction current can be passed through the dynamic focus coil 14 via the dynamic focus driver 26.

In other words, the amount of correction for the pincushion distortion shown in Figure 3 is -2X2Y...(1) for the vertical correction and -KIXY2...(2) for the horizontal correction. The value of equation (1) is added to the corrected vertical deflection signal Y' output from the linear distortion correction circuit 19, and the value of the equation (2) is added to the corrected horizontal deflection signal Y' output from the linear distortion correction circuit 15. Deflection signal
By adding to ', the pincushion distortion can be corrected as shown by the solid line in FIG. Also, the dynamic focus amount can be approximated by -(kl X2+ 2 Y”),
Correction can be performed by dynamically changing the convex lens of the electronic lens to a lens with a longer focal length by the above-mentioned correction amount as it goes toward the periphery. In addition, for linearity distortion correction, the horizontal deflection signal X and the vertical deflection signal Y are sent through a linearity distortion correction circuit 15. Furthermore, orthogonal distortion can be removed by adding + or - ΔY to the corrected horizontal deflection signal By connecting the variable resistor 24 between the vertical deflection signal Y and the output -Y of the inverting amplifier 23, a necessary correction amount output can be obtained.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a display device that can particularly display high-resolution data in a high-definition and easy-to-see manner.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a diagram for explaining the operation of a general flat cathode ray tube, and FIG. 3 is a diagram showing the cause of pincushion distortion on a phosphor screen. FIG. 4 is a diagram showing orthogonal distortion on the phosphor screen. 11...Planar cathode ray tube, 12...Horizontal deflection coil, 13...Vertical deflection coil, 14
・Old...Dynamic focus coil, 15.19・
・・・・・・Linearness distortion correction circuit, 16・Old・・Horizontal deflection driver, 20・・・・Vertical deflection driver, 17.1
8, 21.22... Multiplier, 23...
Inverting amplifier, 25. Old adder, 26. Dynamic focus driver.

Claims (4)

[Claims] (1) In a display device that displays input data using a cathode ray tube, a linearity correction means for correcting the linearity of a scanning electron beam, a pincushion-like deflection distortion correction means for correcting a pincushion-like deflection distortion, and a phosphor screen. dynamic focusing means for keeping the scanning electron beam spot in focus, each of these means operating in accordance with the scanning coordinate position of the scanning electron beam. (2) The display device according to claim 1, further comprising means for correcting the orthogonality of the vertical deflection and the horizontal deflection. (3) The display device according to claim 1, wherein the cathode ray tube is a flat cathode ray tube with a large display screen. (4) The display device according to claim 1, wherein the input data is high resolution data obtained by optically scanning a document.