US 4,658,188 A · Apparatus and method for scanning a flat screen cathode ray tube

Abstract

The disclosure relates to an apparatus and method for forming a scanning electron beam for use in a flat screen cathode ray tube device. An analog addressing method enables scanning of one axis of the screen of the CRT device. During scanning, all portions of a sheet of electrons emitted by a line cathode are deflected at any given time and blocked by an analog horizontal-positioning deflection grid except for one narrow portion disposed along the length of the line cathode. At the one portion, a narrow beam of electrons is formed. The grid contains an address plate and a load plate. The load plate creates a voltage gradient causing each location along its horizontal axis to be at a distinct voltage. Horizontal scanning is accomplished by applying a varying central voltage to the address plate. This varying voltage will be matched by an equal voltage at a single predetermined location along the horizontal axis of the load plate adjacent to which electrons can pass undeflected in the form of a beam. At all other locations along the horizontal axis, unequal voltages on the plates deflect electrons in the sheet passing between them and cause the electrons to be blocked. Vertical scanning is accomplished by varying the voltage difference between two parallel vertical deflection plates between which the scanned electron beam passes. The disclosure also relates to the use of electromagnetic rather than electrostatic deflections in producing a scanning electron beam from a line cathode. In addition, the disclosure relates to multiple beams for scanning and producing of color images.

Claims42

Dependent claims

A system for forming a scanning electron beam comprising:

means for emitting electrons in a plane extending from the length of a predetermined line at substantially a right angle thereto to form a sheet of emitted electrons;
means extending parallel to the predetermined line of the electron emitting means and to the sheet of emitted electrons for applying a reference field extending transverse to the direction of emission of the sheet of emitted electrons;
means disposed adjacent the reference field applying means for generating a scanning field to be applied by the field applying means, the scanning field having a predetermined magnitude extending over the length of the scanning field applying means which is sufficient to deflect the electrons from the plane of the sheet of electrons adjacent the major portion of the length of the scanning field, the resultant field of the reference field and the scanning field having a predetermined magnitude extending over a minor portion of the length of the scanning field applying means which permits the electrons of the portion of the sheet of electrons adjacent to the minor portion to remain as a beam of electrons adjacent the plane of the sheet of electrons, the scanning field having a predetermined rate of scanning of the predetermined magnitude with respect to the length of the scanning field applying means.

A cathode ray tube device comprising:

a system for forming a scanning electron beam including
means for emitting electrons in a plane extending from the length of a predetermined line at substantially a right angle thereto to form a sheet of emitted electrons;
means extending parallel to the sheet of emitted electrons for applying a reference field extending transverse to the direction of emission of the sheet of emitted electrons;
and
means disposed adjacent the field applying means for generating a scanning field to be applied by the field applying means, the scanning field having a predetermined magnitude extending over the length of the scanning field applying means which is sufficient to deflect the electrons from the plane of the sheet of electrons adjacent the major portion of the length of the scanning field, the resultant field of the reference field and the scanning field having a predetermined magnitude extending over a minor portion of the length of the scanning field applying means which permits the electrons of the portion of the sheet of electrons adjacent to the minor portion to remain as a beam of electrons adjacent the plane of the sheet of electrons, the scanning field having a predetermined rate of scanning of the predetermined magnitude with respect to the length of the scanning field applying means;
means spaced apart from the means for emitting electrons for forming a visual image in response to the electrons of the portion of the sheet of electrons adjacent the minor portion which remain adjacent the plane of the sheet of electrons;
and
means for deflecting the scanning electron beam in a direction substantially at right angles to the plane of the sheet of electrons to form a two-dimensional image on the image forming means.

5 more elements

A method for forming a scanning electron beam comprising the steps of:

emitting electrons in a plane extending from the length of a predetermined line at substantially a right angle thereto to form a sheet of emitted electrons;
applying a reference field extending transverse to the direction of emission of the sheet of emitted electrons;
generating a scanning field to be applied to the plane of the sheet of emitted electrons transverse to the direction of emission of the sheet of electrons, and overlapping the reference field, the scanning field having a predetermined magnitude extending over a major portion of the length of the scanning field which is sufficient to deflect the electrons from the plane of the sheet of electrons adjacent the major portion of the length of the scanning field, the resultant field of the reference field and the scanning field having a predetermined magnitude extending over a minor portion of the length of the scanning field which permits the electrons of the portion of the sheet of electrons adjacent to the minor portion to remain as a beam of electrons adjacent the plane of the sheet of electrons, the scanning field having a predetermined rate of scanning of the predetermined magnitude with respect to the length of the scanning field.

Dependencies are inferred from the claim text.

Apparatus and method for scanning a flat screen cathode ray tube

Life of this patent

Apparatus and method for scanning a flat screen cathode ray tube

Life of this patent

Abstract

Claims42