Abstract: Dynamic adjustment techniques for aligning video images in cathode ray tube (CRT) devices are disclosed. A host computer stores correction factor data and video image data in video graphics controller RAM. The host computer processes and transmits the correction factor data, representative of the cathode ray tube distortion characteristics, to the CRT device during the retrace time of the electron beam and video image data during the trace time. The correction factor data may be generated by a vision system, a gain matrix table, interpolation engine or manual methods. Circuitry, within the CRT device, for separating the correction factor data from the video signal is disclosed along with the methods and apparatus used to decode correction data. Data can also be transferred from the monitor back to the host computer over the video connector.

Abstract: A system for automatically aligning video images on display devices such as cathode ray tube (CRT) monitors that use the processor and memory of a host computer to implement the alignment process. The system uses a host computer processor and previously generated correction factor data, representative of specific display distortion characteristics, to produce driver signals necessary to affect the alignment of video images on a CRT screen. The previously stored correction factor data may be retrieved from a characterization module within the display device or from any other convenient storage location. The correction factor data is processed by the host computer to produce correction control data which is transmitted, over a bi-directional serial connector, or a video connector, to the display device where the data is read by correction and driver circuitry.

Abstract: Disclosed is a high-speed approximation device that generates zone correction values in both the horizontal and vertical directions. Group correction values are stored for specific physical locations on the screen for each correction factor parameter. Higher resolution correction signals can be produced by generating zone correction values. Zone correction values are produced for binary fractional addresses that correspond to specific physical locations on the screen. By addressing specific binary fractional addresses that correspond to the location of the video image on the screen, new group correction values do not have to be produced each time the horizontal or vertical size or centering or frequency of the video image is changed. Additionally, by using start addresses and end addresses, zone correction values only have to be produced for the area which the video image occupies on the screen.

Abstract: A system and method for dynamic adjustment of video images on a cathode ray tube in diverse geographic local magnetic fields. The present invention uses a CRT magnetometer that accurately senses differences in the strength and direction of a local magnetic field in three axes, i.e., the x, y, and z axes. The cathode ray tube includes a digital monitor board or monitor circuitry that has a processor and memory and is capable of retrieving correction factor data and magnetic correction data generated by a vision system. The digital monitor board receives CRT magnetometer signals and uses the signals with magnetic correction data to adjust the correction factor data to generate locale specific correction factor data for the sensed local magnetic field. The digital monitor board is capable of decoding the locale specific correction factor data using DACs, PDMs, PWMs, and interpolation engines to generate correction signals that are used to adjust the video image to correct for magnetically induced distortion.

Abstract: A circuit within a video monitor for making corrections during horizontal scan includes a data storage device containing information relating to a selected display parameter, an integrator receptive of the stored information and adapted to produce an integrated signal therefrom, and an amplifier receptive of the integrated signal for supplying signals to the video monitor based on the integrated signal. The information supplied from the data storage device to the integrator is encoded in a pulse density modulated waveform via a tri-state gate and a one-shot timer. The information stored in the data storage device is stored in bytes, each byte containing a "sign bit" and a plurality of data bits. The present invention also discloses the use of an on-screen display chip that uses stored fonts to generate a pulse-density modulated signal. Gradients between rows of fonts can be generated using selected fonts from a font gradient table or can be produced using an up-down counter.

Abstract: A system for generating correction factor data that is representative of the distortion characteristics of a cathode ray tube. The correction factor data is stored with a cathode ray tube to allow later alignment of a video signal, or can be provided on a storage medium or on a network. Distortion data, and resultant correction factor data is generated for a series of discrete physical locations on the cathode ray tube screen. In this manner, the entire screen surface can be utilized to align a video image. Maximum correctable distortion data is also generated in accordance with the present invention to provide exit criteria for cathode ray tube manufacturers. The exit criteria is based upon maximum correction factor data that can be generated to correct distortions.

Abstract: An apparatus and method are disclosed for generating timing pulses to control various functions in a video monitor including the switching of video amplifiers in cathode ray tube (CRT) devices, the control of the phase and frequency of phase locked loops, etc. Unlike previous methods, where switching is timed and controlled by monitoring the retrace voltage level, the system of the present invention monitors the change in direction of current in the retrace tuning capacitor. Monitoring the retrace capacitor current, provides an extremely accurate method for timing in horizontal deflection circuits. The apparatus of the present the invention comprises a small bead inductor placed in the current path of a horizontal retrace capacitor within the horizontal deflection circuit of the cathode ray tube device. Measuring the voltage across the bead inductor allows a very precise monitoring of the current through the retrace tuning capacitor.

Abstract: A system for synchronous alignment of cathode ray tube (CRT) rasters by application of time variable rotation driver signals to the CRT rotation coil during trace of the raster. The system may be implemented by either digital or analog means of measuring and storing cathode ray tube raster distortion data as rotational correction factor data. The rotational correction factor data is used by device circuitry to generate and apply the required time variable rotation driver signals, to the CRT rotation coil, to effect the desired CRT raster alignment.

Abstract: A circuit within a video monitor for making corrections during horizontal scan includes a data storage device containing information relating to a selected display parameter, an integrator receptive of the stored information and adapted to produce an integrated signal therefrom, and an amplifier receptive of the integrated signal for supplying signals to the video monitor based on the integrated signal. The information supplied from the data storage device to the integrator is encoded in a pulse density modulated wave form via a tri-state gate and a one-shot timer. The information stored in the data storage device is stored in bytes, each byte containing a "sign bit" and a plurality of data bits.

Abstract: A interpolation engine is disclosed that is capable of generating correction signals for segments of a monitor that form a gradient that eliminates any visual discontinuities between segments on the screen. In one embodiment, a starting count number for a distortion signal is stored in RAM, together with an increment rate signal that indicates the rate of change of the correction signal down the segment. In another embodiment, the increment rate signal is automatically calculated by the device by taking the difference between the starting count numbers for vertically adjacent segments. Since the number of rows in each segment is known and the difference between the starting count numbers of vertically adjacent segments is determined, the amount of correction for each row within a segment is calculated and provided as a correction signal. Hence, a correction signal can be provided for each row of pixels on a screen.

Abstract: A circuit within a video monitor for making corrections during horizontal scan includes a data storage device containing information relating to a selected display parameter, an integrator receptive of the stored information and adapted to produce an integrated signal therefrom, and an amplifier receptive of the integrated signal for supplying signals to the video monitor based on the integrated signal. The information supplied from the data storage device to the integrator is encoded in a pulse density modulated wave form via a tri-state gate and a one-shot timer. The information stored in the data storage device is stored in bytes, each byte containing a "sign bit" and a plurality of data bits.

Abstract: An automatic precision video monitor alignment and calibration system is described which functions to precisely align all of the adjustable display characteristics of a video monitor to a high degree of precision. This alignment system can function in an automated calibration mode wherein it is independent of human input and automatically performs a series of alignment/calibration operations to precisely adjust all of the display characteristics of the video monitor in a fraction of the time required by a person to manually align the video monitor. The alignment system includes a digital control circuit located within the video monitor to precisely set and maintain each of the monitor display characteristics. The values maintained by this control circuit can be input by a person, or set automatically by a computer controlled display alignment system.