Method and apparatus for automatically calibrating a graticuled cathode ray tube

Claim 1

An apparatus for automatically calibrating the deflection of an electron beam in a cathode ray tube including a graticuled faceplate, comprising: a graticule having a pattern of lines mounted on the faceplate for optically coupling light into the faceplate, the coupled light reflected internally within the faceplate toward its edges; amplifying means coupled to the cathode ray tube for deflecting the electron beam; signal generating means coupled to the amplifying means for generating a plurality of input signals of a predetermined accuracy to deflect the electron beam across a graticule line of the faceplate; photoelectric means mounted adjacent to an edge of the faceplate for detecting the internally reflected light and generating in response a detection signal; signal comparing means coupled to the signal generating means and the photoelectric means for comparing the detection signal to its corresponding input signal; adjustment means in communication with the signal comparing means and amplifying means for adjusting the amplifying means to cause the electron beam to coincide with a graticule line that correctly represents the input signal causing the deflection; and modulating means for modulating the electron beam and signal processing means for demodulating detection signals produced by the photoelectric means to improve the detectability of electron beam coincidence with the graticule line in the presence of electrical and optical noise.

Claim 2

An apparatus for automatically calibrating the deflection of an electron beam in a cathode ray tube including a graticuled faceplate, comprising: a graticule having a pattern of lines mounted on the faceplate for optically coupling light into the faceplate, the coupled light reflected internally within the faceplate toward its edges; amplifying means coupled to the cathode ray tube for deflecting the electron beam; signal generating means coupled to the amplifying means for generating a plurality of input signals of a predetermined accuracy to deflect the electron beam across a graticule line of the faceplate; photoelectric means mounted adjacent to an edge of the faceplate for detecting the internally reflected light and generating in response a detection signal; signal comparing means coupled to the signal generating means and the photoelectric means for comparing the detection signal to its corresponding input signal; adjustment means in communication with the signal comparing means and amplifying means for adjusting the amplifying means to cause the electron beam to coincide with a graticule line that correctly represents the input signal causing the deflection; and modulating means for modulating the electron beam and signal processing means for demodulating detection signals produced by the photoelectric means to improve the detectability of electron beam coincidence with the graticule line in the presence of electrical and optical noise.

Claim 5

An apparatus for automatically calibrating the deflection of an electron beam in a cathode ray tube including a faceplate having a layer of phosphor material thereon, comprising: amplifying means associated with the cathode ray tube for deflecting the electron beam; a graticule having lines mounted on the faceplate for optically coupling into the faceplate light generated by the electron beam striking the phosphor over a graticule line, the light reflected internally within the faceplate toward its edges; control means for generating a plurality of input signals; analog voltage generating means coupled to the control means to receive input signals therefrom for converting the signals to analog voltages of a predetermined accuracy to deflect the electron beam across a graticule line of the faceplate; modulating means for modulating the electron beam; photoelectric means mounted adjacent to an edge of the faceplate for detecting the light coupled into the faceplate and internally reflected therein, the photoelectric means generating in response to each beam coincidence with a graticule line a detection signal; signal processing means for demodulating the electrical signals to retrieve the detection signals; signal comparing means for comparing the detection signals with the input signals; and adjustment means for adjusting the amplifying means in response to the comparison of the input signals with the detection signals to cause the electron beam to coincide with a graticule line that correctly represents the input signal causing the deflection.

Claim 6

An apparatus for automatically calibrating the deflection of an electron beam in a cathode ray tube including a faceplate having a layer of phosphor material thereon, comprising: amplifying means associated with the cathode ray tube for deflecting the electron beam; a graticule having lines mounted on the faceplate for optically coupling into the faceplate light generated by the electron beam striking the phosphor over a graticule line, the light reflected internally within the faceplate toward its edges; control means for generating a plurality of input signals; analog voltage generating means coupled to the control means to receive input signals therefrom for converting the signals to analog voltages of a predetermined accuracy to deflect the electron beam across a graticule line of the faceplate; modulating means for modulating the electron beam; photoelectric means mounted adjacent to an edge of the faceplate for detecting the light coupled into the faceplate and internally reflected therein, the photoelectric means generating in response to each beam coincidence with a graticule line a detection signal; signal processing means for demodulating the electrical signals to retrieve the detection signals; signal comparing means for comparing the detection signals with the input signals; and adjustment means for adjusting the amplifying means in response to the comparison of the input signals with the detection signals to cause the electron beam to coincide with a graticule line that correctly represents the input signal causing the deflection.