Dual display monitor

• US 4,677,481 A
• Filed: 03/17/1986
• Issued: 06/30/1987
• Est. Priority Date: 03/17/1986
• Status: Expired due to Term

• Current Assignee: Tektronix Incorporated (Fortive Corp.)
• Original Assignee: Tektronix Incorporated (Fortive Corp.)
• Inventors: Nicholas, Dan H.
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US06/840,101
• Time in Patent Office: 470 Days
• Field of Search: 358/139, 358/88, 358/92, 358/10, 358/3, 324/77 R, 324/88, 340/705, 340/720, 340/721, 340/722, 340/734
• US Class Current: 348/184
• CPC Class Codes: H04N 5/45 Picture in picture , e.g. displaying simultaneously another television channel in a region of the screen

Abstract

A waveform monitor for television has dual video channels displayed simultaneously side-by-side. The two channels are synchronized with each other or with an external sync signal and are input to a multiplexer prior to the display. A microprocessor controls the switching of the multiplexer according to the selection made by an operator. The first channel is displayed during the first half of the horizontal display sweep, and the second channel is displayed during the second half, the horizontal sweep encompassing two horizontal lines of video.

Claims

1. A dual waveform display device comprising:

means for switching between two channels of synchronized video information in the form of video waveforms having as inputs the two channels of synchronized video information and as an output one of the two channels of synchronized video information; and

means for controlling the switching means so that the two channels are displayed horizontally side-by-side during a single horizontal sweep across the display device.

2. The dual display device as recited in claim 1 further comprising:

sync selection means for switching between the output of the channel switching means and an external video signal under control of the controlling means; and

means for extracting horizontal sync pulses from the output of the sync selection means for input to the controlling means for use by the controlling means in providing the timing for controlling the channel switching means.

3. The dual display device as recited in claim 2 wherein the controlling means comprises:

a microprocessor having as inputs a selected display mode and the horizontal sync pulses from the extracting means, and outputting for each horizontal sync pulse a serial data word to be executed upon the receipt of the next horizontal sync pulse, the serial data word being a function of the selected display mode; and

a latch into which the serial data word is loaded between horizontal sync pulses, and which transfers the serial data word to the latch output upon receipt of the next horizontal sync pulse.

4. The dual display device as recited in claim 3 wherein the channel switching means comprises a modulator circuit configured as a multiplexer so that the output of the multiplexer is determined by the serial data word at the output of the latch, the input being the two channels of video information.