The present invention concerns an image display method and an image display circuit for superimposing digital video data on external digital video data. An object of the invention is to provide an image display method and a display circuit through which color bleeding and image flickering are not generated on an image-generated based on the external digital video data when the digital video data is superimposed on the external digital video data. A comparison shift clock whose phase is led from ...

A three-pole double-throw switch is provided to selectively interrupt the video signal from an input connector to an output connector for display of white characters generated by a microprocessor on a dark screen of a CRT monitor, or vice versa, and route the video signal through an inverter for display of dark characters on white screen. One pole of the switch is used to provide the vertical sync signal to the power input terminal of the inverter, thus powering the select switch box solely from...

A method for automatically calibrating a touch screen used in conjunction with a graphic display is executed prior to every interactive session. Three points, defining perpendicular axes, are displayed and an operator is instructed to touch the touch screen at each of the points in succession. Coordinates for the three points output by the touch screen are checked for reasonableness and perpendicularity. If these checks are passed, a coordinate translation matrix is generated for converting touc...

A touch panel input apparatus including two arrays of light detectors placed on the opposite sides of the display device screen and four light sources, each of which is placed at a corner and at angle to illuminate at least the entire array of the light detectors on the opposite side. The light detectors are scanned in synchronization with the selection of the light beam sources. A controlling microprocessor has stored in its memory four sets of data, one for each light source, regarding ambient...

A keyboard switch includes a plurality of spaced piezoelectric transducers secured to a common strike plate which is selectively impacted to actuate all of the transducers in response to switch actuation. The switch includes a snap action spring member carrying an impact member which impacts the strike plate as the spring member snaps to its actuated state when the switch is depressed . The spring member causes the impact member to maintain a compressive force against the strike plate, maintaini...

A lighted sign, particularly useful for identifying a residence number on a street, has a display panel having a plurality of aligned numbers illuminated by LED's which are selectively programmable by the user to display the proper house number. In the event of an emergency, the sign is changeable to an emergency mode in which the numbers flash intermittently, and the LED's change from a first color to a red color indicating the emergency. The sign is activated manually or by means of a photocel...

A predetermined display period is divided into a plurality of shorter display periods. Image data is stored in an image memory and read in accordance with a period for reading the data from the memory. An accessing period is also provided, and access to the memory is made when the addressing mode is being set in a mode register during the accessing period, whereby the data is displayed by raster scanning.

This invention is concerned with systems that create video images. Previously these systems have been limited to ones which create images of television type resolution, however, the systems of this invention may produce an image of higher resolution. The operator draws on a touch tablet and chooses a color and implement type and a line is produced which appears on a screen in approximately real time. At the same time a corresponding line is being produced and written in at high resolution to a l...

A digital stroke generator reads and writes discrete stroke segments in a display memory. The generator comprises principally a line address register, a column address register, a command addresser, a counter and it may also include a data register. The command addresser which commands the incrementation and decrementation of the address registers comprises an octant register, a direction register in which the vector direction is memorized according to the ROTHMAN code and a transcoding matrix. ...

An AC gas discharge display panel is described which employs the phenomenon of plasma spreading. In the panel, plasma spreading or "coupling" is employed to couple the plasma to an addressed cell to one of a plurality of pixels to be illuminated. The spreading is controlled by assuring that the cell wall voltages are properly related so that the plasma's electrons migrate to a region where the voltages are approximately equal to or more positive than the wall voltages where the plasma originated...