Abstract: Electron gun for cathode ray tube comprising aligned in series along an axis XX? an electron-emitting cathode K, electrodes G1 and G2 for the formation of an electron beam, a prefocusing electron lens G3, G4, G5, a first quadripolar device G7, G8 electrically controlled in a dynamic manner in synchronism with the screen scan so as to correct beam focusing defects at the screen edge, a main electron lens G8–G9 making it possible to focus the electron beam onto a screen. It also comprises a second quadripolar device G5, G6, G7situated between the prefocusing electron lens G3, G4 and the first quadripolar device and comprising electrodes G5, G6, G7exhibiting rectangular apertures. Those of G5 and G7 are parallel and those of G6 are orthogonal to those of G5 and G7. The electrodes G5 and G7 are placed at a fixed polarization potential, and the electrode G6 is at a polarization potential varying in synchronism with the screen scan.

Abstract: An electron gun for a color cathode ray tube includes a cathode which is a source for emitting an electron beam, a control electrode, through which the electron beam emitted from the cathode passes, having first electron beam passing holes each including a first vertically elongated indented portion formed at an output side surface of the control electrode and a first electron beam passing hole portion formed in the first indented portion, a screen electrode installed adjacent to the control electrode and having second electron beam passing holes formed in the screen electrode, a plurality of focusing electrodes for forming a plurality of quadrupole lenses, sequentially installed from the screen electrode and respectively having electron beam passing holes having a predetermined shape.

Abstract: A focusing electrode and a final accelerating electrode accommodate, respectively, a first and a second field forming electrode in positions set back from a first and a second aperture of their end faces opposed to each other. The first and the second field forming electrode have three electron beam passage apertures disposed in an in-line arrangement. When the in-line direction is an X-axis direction, a direction perpendicular to the in-line direction is a Y-axis direction and the center of a central electron beam passage aperture formed in the first field forming electrode is X=0 and Y=0, the central electron beam passage aperture has a shape that passes through the intersection points of the X-axis and the Y-axis with a curve represented by the equation (X/R1)2+(Y/R2)2=1 (where R1 and R2 are constants) and that has an area smaller than the area encircled by the curve.

Abstract: An electron gun assembly for a CRT includes three cathode electrodes, a control electrode, an electron-stream extractor electrode, a focusing electrode, and an anode electrode. The electron-stream extractor electrode includes first, second, and third holes, each of which allows one of the three streams of the electrons to pass through. The focusing electrode includes a flat portion having fourth, fifth, and sixth holes, each of which allows one of the three streams of the electrons to pass through. The first, second, and third holes are arranged in the in-line direction. Each of the fourth and sixth holes includes a substantially rectangular opening and a substantially semicircular opening connected to each other. One side of the substantially rectangular opening is connected to a straight line segment of the substantially semicircular opening, and the substantially rectangular opening is disposed outside while the substantially semicircular opening is disposed inside.

Abstract: A cathode-ray tube includes a plate having a first hole on a first surface of the plate and a second hole on a second surface of the plate. The first and second holes coupled together to allow electron beams to pass therethrough. The plate is a unitary structure. The first hole is formed by initiating a first hole formation from the first surface, and the second hole is formed by initiating a second hole formation from the second surface. The first surface is on an opposing side of the second surface.

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.

Abstract: A method and a apparatus are provided for operating an E-beam system including an E-beam source for generating an E-beam directed along a column axis and an electrode aligned with the column axis direct the E-beam towards means for measuring the E-beam. A signal proportional to leakage current emitted from the E-beam is generated. When the result of a comparison with a desired value is excessive, an excess leakage signal is generated. The excess leakage signal can be provided as an emergency output signal and/or produce an OFF signal for stopping production of the E-beam by turning OFF voltage/power sources for producing the E-beam in response to the excess leakage signal. Preferably, a filament is heated by an electric current and a cathode is bombarded with electrons from the filament to produce the E-beam. Then a filament control signal is employed for controlling the filament heating current.

Abstract: An electron gun for a cathode ray tube has a cathode structure, a control electrode, a screen electrode, focusing electrodes, and a final accelerating electrode. R, G, and B electron apertures of one pair of the focusing electrodes face each other to form a quadrupole lens unit, to which an AC voltage having a relatively low peak or a static voltage is applied to converge R, G, and B electron beams into one point, even when the electron beams deviate to the corner of a screen. Asymmetrical enlargement portions are included in the rims of each of the R and B electron beam apertures.

Abstract: An electron gun assembly of a cathode ray tube has a main electron lens section comprising at least four electrodes, provided in a sequence of first, second, third and fourth grids, a middle first voltage is applied to the first grid, and an anode voltage is applied to the fourth grid. The adjacent second grid and third grid are connected by a resistor, and second and third voltages of substantially the same potential, corresponding to voltages higher than the middle first voltage and lower than the anode voltage, are applied thereto. An asymmetrical lens is provided between the adjacent second grid and the third grid second lens region, and a voltage which changes in synchronism with the deflecting magnetic field is applied to the first grid.

Abstract: A method of mounting a signal outputting electrode for outputting an electric signal generated in an envelope of a cathode ray tube to the outside without being adversely influenced by a getter. A signal outputting electrode is mounted in an area which is not covered with an internal conductive film in a state where the periphery of the electrode is apart from an inner wall of a funnel via an intermediate member. When a getter is introduced into the tube in the state where the signal outputting electrode is mounted, the getter is prevented from reaching the intermediate member. It therefore prevents conduction between the signal outputting electrode and the inner conductive film.

Abstract: A color display device (19) is disclosed with an improved focus performance. In present-day color display tubes with DAF, the electron gun is provided with a second focusing electrode (25) driven with a dynamic voltage which is varied synchronously with the deflection field. The dynamic quadrupole lens formed between the first focusing electrode (23) and the second focusing electrode (25) is designed in such a way that the horizontal lens action, which arises when the voltage on the second focusing electrode is increased, should be compensated by the main lens which becomes weaker when the voltage on the second focusing electrode (25) is increased. In practice, it is not possible to achieve this in the required range of the dynamic voltage on the second focusing electrode (25), leading to a deterioration of the focus performance of the color display device (19). This problem is solved by the present invention.