Display systems

Claim 2

An image display system, comprising projection means for projecting a deflectable beam of energy on to a surface for producing an image thereon in dependence on the beam intensity, first and second analog deflection means respectively energisable by predetermined first and second electrical analog signals to deflect the beam in first and secoNd transverse directions which are of substantially constant orientation over a particular portion of the surface, digital correction means including correction data storage means for digitally storing data indicative of corrections to be applied to the first and second analog signals to cause the deflection means to drive the point of scan along a raster of lines on the surface whose orientation is predetermined and diferent from the first and second directions, digitally controlled scan control means operative to generate the first and second analog signals for application to the first and second deflection means respectively and including means operative to feed each analog signal to the correction means to subject each signal, before the signal is applied to the respective deflection means, to direct multiplication by the value of the corresponding digital correction data read out from the storage means, means operative to energise the first and second deflection means simultaneously with the corrected first and second analog signals to drive the point of scan along the said raster of lines, and intensity control means for controlling the intensity of the beam as the point of scan moves along the raster, so as to produce a desired image pattern on the surface.

Claim 3

A system according to claim 1, in which the intensity control means comprises storage means for storing, for each point on the lines, data indicative of a desired beam intensity at that point, and means operative to read the data as the point of scan moves along the raster and to control the intensity of the beam accordingly.

Claim 4

A system according to claim 1, in which the first and second analog signals generated by the scan control means are progressively changing when applied to the first and second deflection means respectively, the signals changing at such rates as to produce the desired raster.

Claim 5

A system according to claim 3, in which the scan control means includes means responsive to the end of each line of the raster to produce a predetermined step change in each said analog signal of such magnitude as to bring the point of scan to the beginning of the next line of the raster.

Claim 6

A system according to claim 1, in which the projection means comprises the cathode gun of a cathode ray tube whereby the said beam is a beam of electrons in the cathode ray tube, and the said surface comprises the screen of the cathode ray tube.

Claim 7

A system according to claim 5, in which the first and second deflection means respectively comprise the X deflection means and the Y deflection means of the cathode ray tube which are respectively electrically energisable to drive the electron beam spot in x and y directions over the tube screen, the said directions being of substantially constant and relatively transverse orientation over the said particular portion of the screen, and the scan control means is operative to energise the X and Y deflection means simultaneously with said analog signals of such relative value that the said raster of lines on the screen along which the beam spot is driven have an orientation which is predetermined and different from the x and y directions.

Claim 8

In a cathode ray tube image display system comprising a cathode ray tube having a cathode gun for projecting a deflectable beam of electrons onto the cathode ray tube screen for producing an image thereon in dependence on the beam intensity, and X and Y deflection means respectively energisable by predetermined first and second electrical analog signals to deflect the beam in x and y transverse directions over the tube screen which are of substantially constant and relatively transverse orientation over a particular portion of the screen, digital correction means including correction data storage means for digitally storing data indicative of corrections to be applied to the first and second analog signals to cause the Deflection means to drive the point of scan along a raster of lines on the screen whose orientation is predetermined and different from the x and y directions, first means for generating the said first electrical analog signals, second means for generating the said second electrical analog signals, a source of clock pulses connected to feed clock pulses to digitally drive the first and second means, each of the first and second means including first analog means responsive to the clock pulses to generate respective said electrical analog signals which change progressively in predetermined increments, and means for feeding the respective analog signals from the analog means to the ditital correction means, before each analog signal is applied to the respective deflection means, to subject each signal to a correction determined by corresponding digital correction data read out from the storage means, means operative to energise the X and Y deflection means simultaneously with the corrected first and second analog signals to drive the point of scan along the said raster of lines, and intensity control means for controlling the intensity of the beam as the point of scan moves along the raster, so as to produce a desired image pattern on the screen.

Claim 9

In a cathode ray tube image display system comprising a cathode ray tube having a cathode gun for projecting a deflectable beam of electrons onto the cathode ray tube screen for producing an image thereon in dependence on the beam intensity, and X and Y deflection means respectively energisable by predetermined first and second electrical analog signals to deflect the beam in x and y transverse directions over the tube screen which are of substantially constant and relatively transverse orientation over a particular portion of the screen, digital correction means including correction data storage means for digitally storing data indicative of corrections to be applied to the first and second analog signals to cause the Deflection means to drive the point of scan along a raster of lines on the screen whose orientation is predetermined and different from the x and y directions, first means for generating the said first electrical analog signals, second means for generating the said second electrical analog signals, a source of clock pulses connected to feed clock pulses to digitally drive the first and second means, each of the first and second means including first analog means responsive to the clock pulses to generate respective said electrical analog signals which change progressively in predetermined increments, and means for feeding the respective analog signals from the analog means to the ditital correction means, before each analog signal is applied to the respective deflection means, to subject each signal to a correction determined by corresponding digital correction data read out from the storage means, means operative to energise the X and Y deflection means simultaneously with the corrected first and second analog signals to drive the point of scan along the said raster of lines, and intensity control means for controlling the intensity of the beam as the point of scan moves along the raster, so as to produce a desired image pattern on the screen.

Claim 10

A system according to claim 7, including means responsive to the completion of each line of the said raster to produce a respective electrical line pulse, and in which each of the first and second means also includes second analog means digitally driven by each said line pulse to generate respective said electrical analog signals which change progressively in predetermined increments in response to the said line pulses, and means for feeding the electrical analog signals from the second analog means to the digital correction means to subject them to the said corrections, the said means for feeding the analog signals to the deflection means comprising, for each of the deflection means, respective algebraic adding means for algebraically adding each said analog signal generated by the second analog means and corrected by the correction means to the analog signals corresponding to the same line of the raster and generated by the first analog means and corrected by the correction means, whereby to produce a resultant said analog signal being the algebraic total of the two analog signals added, and means for feeding the said resultant analog signal to energise the respective deflection means, the incremental changes in the analog signals generated by the second analog means and the corrections applied thereto by the correction means being such that one end of each line of the raster lies on a predetermined, transverse, base line, and the lines of the raster are separated by a predetermined distance.

Claim 11

A system according to claim 8, in which each said analog means comprises a register responsive to the said pulses and operative to produce a progressively changing electrical digital signal, and a digital-to-analog converter response to the digital signal to produce a correspondingly changing electrical analog signal, and the said digital correction means comprises storage means for storing fixed correction signals, and multiplying means for multiplying the fixed signals with the respective electrical analog signals whereby to correct the value of the respective said analog signal.

Claim 12

A system according to claim 8, in which each of the first and second means includes means for generating a respective further said electrical analog signal representing a respective x and y coordinate of the initial point of the first line of the raster, and each said algebraic adding means includes means for adding the respective further analog signal to the other analog signals to produce the said resultant analog signal.

Claim 13

A system according to claim 7, in which the beam intensity control means comprises intensity control storage means for storIng a respective group of items of data for each line of the raster, the successive items of data of each group respectively defining the lengths of the successive portions of spot movement over which the beam intensity is to be constant at a predetermined level, means responsive to the said clock pulses and operative to read from the said intensity control storage means the data corresponding to each point on the lines of the raster in synchronism with the movement of the spot along the lines of the raster, whereby to produce an intensity control signal whose value depends on the beam intensity indicated by the said data, and means for feeding the intensity control signal to the electron gun to control the beam intensity.

Claim 14

A system according to claim 8, in which the beam intensity control means comprises intensity control storage means for storing a respective group of items of data for each line of the raster, the sucessive data items of each group respectively defining the lengths of the successive portions of spot movement over which the beam intensity is to be constant at a predetermined level, and the item of data respresenting the last said portion of each line of the raster (in the direction in which the spot moves therealong) which is to be of relatively high intensity being specially coded, means responsive to the said clock pulses to read out from the intensity control storage means the data corresponding to each point on the lines of the raster as the spot moves therealong whereby to produce an intensity control signal whose value depends on the beam intensity indicated by the read data, and means for feeding each intensity control signal to the electron gun for controlling the beam intensity in dependence thereon; and in which the said means for producing the line pulses comprises means for detecting each said specially coded item of data and producing a respective said line pulse in response thereto.

Claim 15

A system according to claim 1, in which the projection means comprises a laser beam source.

Claim 16

An image display system, comprising projection means for projecting a deflectable beam of energy onto a surface for producing an image thereon in dependence on the beam intensity, digitally controlled scan control means including beam deflection means and operative to scan the beam along a raster of lines on the surface whose orientation thereon is predetermined by stored digital data, intensity control storage means for storing, for each point on the lines, digital data indicative of a desired beam intensity at that point, the stored data indicative of the last point on each line (in the direction in which the line is scanned) which is to be of sensible intensity being specially coded, intensity control means operative to read out from the intensity control storage means the items of data as the point of scan moves along the raster and to produce intensity control signals of magnitude determined by the read-out items of data, means for feeding the said intensity control signals to the projection means for controlling the beam intensity in dependence thereon, means for detecting the special code when the item of data indicative of the last point on each line is read out, and operative to produce a special signal in dependence thereon, and means for feeding the special signal to the scan control means to terminate the scan of each line and to initiate the scan of the next line.

Claim 17

An image display system, comprising projection means for projecting a deflectable beam of energy onto a surface for producing an image thereon in dependence on the beam intensity, digitally controlled scan control means including beam deflection means and operative to scan the beam along a raster of lines on the surface whose orientation thereon is predetermined by stored digital data, intensity control storage means for storing, for each point on the lines, digital data indicative of a desired beam intensity at that point, the stored data indicative of the last point on each line (in the direction in which the line is scanned) which is to be of sensible intensity being specially coded, intensity control means operative to read out from the intensity control storage means the items of data as the point of scan moves along the raster and to produce intensity control signals of magnitude determined by the read-out items of data, means for feeding the said intensity control signals to the projection means for controlling the beam intensity in dependence thereon, means for detecting the special code when the item of data indicative of the last point on each line is read out, and operative to produce a special signal in dependence thereon, and means for feeding the special signal to the scan control means to terminate the scan of each line and to initiate the scan of the next line.

Claim 18

A system according to claim 14, in which the beam deflection means comprises first and second deflection means for respectively deflecting the beam in first and second transverse directions in dependence on respective energisation signals, and means for digitally generating respective progressively changing energisation signals and feeding them to the first and second deflection means simultaneously, the signals changing linearly and at such rates as to produce the desired raster.

Claim 19

A systeM according to claim 14, in which the said projection means comprises the electron gun of a cathode ray tube, the said surface comprises the screen of the cathode ray tube, and the first and second deflection means are the X and Y deflection means respectively of the cathode ray tube.

Claim 20

A system according to claim 14, in which the projection means comprises a laser beam source.