Digitally synthesized gray scale for raster scan oscilloscope displays

An improvement to a digitizing oscilloscope, said digitizing oscilloscope having means for obtaining a current waveform and a plurality of prior waveforms from a system under test and means connected to said obtaining means for displaying said current and plurality of prior waveforms, each said current and plurality of prior waveforms being formed by a plurality of pixels on said display, said improvement comprising:

• means in said displaying means for providing a gray scale binary field of at least two bits for each of said plurality of pixels in each said current and plurality of prior waveforms,
• means in said displaying means receptive of all of said gray scale binary fields from said providing means for decrementing prior to display by said displaying means, in a predetermined time period, all said gray scale binary fields by a predetermined binary value, said decremented gray scale binary fields replacing, in each said predetermined time period, all of said gray scale binary fields in said providing means,
• means in said displaying means and receptive of all of said decremented gray scale binary fields from said decrementing means for illuminating the corresponding pixels to a predetermined level of brightness as determined by the binary values in said decremented gray scale binary field, said displaying means displaying the current waveform at full brightness and each of said prior waveforms with the same degree of brightness and with each earlier prior waveform having a lower degree of brightness so as to display the direction of said current waveform with respect to said prior waveforms,
• means in said obtaining means and connected to said displaying means for providing said predetermined time period.

A method of digitally synthesizing gray scale in raster scan display systems having a raster scan display, a display memory, and a display control, the display control drawing a current image and a plurality of prior images on the display during a display refresh cycle, the current image and each of the plurality of prior images being formed by a plurality of pixels on the display, said method comprising the steps of:

• (a) providing a gray scale binary field in the display memory of at least two bits for each of the plurality of pixels in each of the current image and the plurality of prior images,
• (b) illuminating the current image at full brightness on the display,
• (c) illuminating the plurality of prior images according to the binary values in the gray scale binary fields corresponding to the prior images,
• (d) decrementing the binary values in all of the grey scale binary fields in the display memory by a predetermined binary value,
• (e) repeating step (d) in a predetermined cycle of time independent of the display refresh cycle time so as to provide uniform linear fade in the illumination of the prior images wherein all of the pixels in a given prior waveform are at the same level of fade and wherein the dimmest image is the oldest prior image so as to display the direction of said current waveform with respect to the prior images,
• (f) selectively adjusting the predetermined cycle of time.

A method of digitally synthesizing gray scale of raster scan display systems having a raster scan display, a display memory, and a display control, the display control drawing graphical information during a display refresh cycle, a current waveform and a plurality of prior images on the display, the graphical information, current waveform and each plurality of the plurality of prior images being formed by a plurality of pixels on the display, said method comprising the steps of:

• (a) providing a gray scale binary field in the display memory of at least two bits for each of the plurality of pixels in each of the current image and the plurality of prior images,
• (b) illuminating the current image at full brightness on the display,
• (c) illuminating the plurality of prior images according to the binary values in the gray scale binary fields corresponding to the prior images,
• (d) decrementing the binary values in all of the gray scale binary fields in the display memory by a predetermined binary value,
• (e) repeating step (d) in a predetermined cycle of time independent of the display refresh cycle time so as to provide uniform linear fade in the illumination of the prior images wherein all of the pixels in a given prior waveform are at the same level of fade and wherein the dimmest image is the oldest prior image so as to display the direction of said current waveform with respect to the prior images,
• (f) when the graphical information and the current and prior images occur at the same pixel illuminating only the current and prior images.

A method of digitally synthesizing gray scale in raster scan oscilloscope display system having a display, a display memory, and a display control, the display control drawing a current waveform and a plurality of prior waveforms on the display during a display refresh cycle time, the current waveform and each of the plurality of prior waveforms being formed by a plurality of pixels on the display, said method comprising the steps of:

• (a) providing a gray scale binary field in the display memory of at least two bits for each of the plurality of pixels in each of the current and the plurality of prior waveforms,
• (b) illuminating the current and first prior waveforms at full brightness on the display so as to minimize flicker,
• (c) illuminating the second and all subsequent prior waveforms according to the binary values in the gray scale binary fields corresponding to the aforesaid prior waveforms,
• (d) decrementing the binary values in all of the gray scale binary fields in the display memory by a predetermined binary value,
• (e) repeating step (d) in a predetermined cycle of time independent of the refresh display cycle time so as to provide fade in the illumination of the prior waveforms wherein the dimmest waveform is the oldest prior waveform so as to display the direction of said current waveform with respect to the prior waveforms,
• (f) selectively adjusting the predetermined cycle of time.

An improvement to a digitizing oscilloscope, said digitizing oscilloscope having means for obtaining a current waveform and a plurality of prior waveforms from a system under test and means for displaying graphical information and said current and plurality of prior waveforms, each said current and plurality of prior waveforms and said graphical information being formed by a plurality of pixels on said display, said improvement comprising:

• means in said displaying means for providing a gray scale binary field for each of said plurality of pixels in said display, each said gray scale binary field having bits, assigned to said graphical information and separate bits assigned to said current and prior waveforms,
• means in said display means receptive of all of said gray scale binary fields from said providing means for decrementing in a predetermined time period after each said display by said displaying means, all said gray scale binary fields by a predetermined binary value, said decremented gray scale binary fields replacing, in each said predetermined time period, all of said gray scale binary fields in said providing means, said displaying means displaying the current waveform at full brightness and each of said prior waveforms with the same degree of brightness and with each earlier prior waveform having a lower degree of brightness so as to display the direction of said current waveform with respect to said prior waveforms,
• means receptive of said decremented gray scale binary fields from said decrementing means for encoding each of said decremented gray scale binary fields to give display priority to said current and prior waveforms over said graphical information based upon the aforesaid bit assignment when said current and prior waveform and said graphical information coincide on the same pixel,
• means in said displaying means and receptive of all of said encoded gray scale binary fields from said encoding means for illuminating the corresponding pixels to a predetermined level of brightness as determined by the binary values in said encoded gray scale binary fields.