Circuit for operating a bar graph display panel

• US 3,967,158 A
• Filed: 01/24/1975
• Issued: 06/29/1976
• Est. Priority Date: 01/24/1975
• Status: Expired due to Term

• Current Assignee: Unisys Corporation
• Original Assignee: Burroughs Incorporated (Terreno Realty Corp.)
• Inventors: Saxon, Richard A.
• Primary Examiner(s): Rolinec, R. V.
• Assistant Examiner(s): Dahl, Lawrence J.
• Application Number:
  US05/543,882
• Time in Patent Office: 522 Days
• Field of Search: 313/514, 315/169 TV, 315/169 R, 340/324 M, 340/324 R
• US Class Current: 345/37
• CPC Class Codes: G01R 13/405 using a plurality of active, i.e. light emitting, e.g. electro-luminescent elements, i.e. bar graphs
• CPC Class Codes: H03M 1/56 Input signal compared with linear ramp

Abstract

A bar graph display panel comprises a gas-filled envelope containing a series of fine, closely-spaced cathode lines connected in groups so that they can be energized sequentially and individually. The panel also includes an anode film supported on the face plate and aligned with and in operative relation with the series of cathode lines. The anode and cathodes are closely spaced and the panel contains an ionizable gas at relatively high pressure.

In order to use the display panel to display a bar of light, the anode and cathodes are connected in an operating circuit wherein each of the cathodes is energized or scanned and caused to glow sequentially. An analog signal to be displayed as a bar of light and a ramp signal are coupled to a comparator, the output of which energizes the anode electrode. When the two input signals are equal, the output of the comparator is zero, the anode is cut off, and the time in the scanning cycle when this occurs determines the number of cathodes which have been energized and the length of the bar of light displayed thereby. The scanning operation is carried out continually at such a rate that the bar of light appears to be stationary but is changeable in accordance with changes in the input analog signal.

Claims

1. A bar graph display system comprising

a display panel comprising a gas-filled envelope including a base plate and a viewing face plate hermetically sealed together,

a plurality of thin, parallel, linear cathodes disposed in a series along the surface of said base plate and positioned sufficiently close together so that, as the series of cathodes is energized and selected cathodes are caused to exhibit cathode glow, the glow of adjacent cathodes appears to blend to form a bar of light, said series of cathodes including a first cathode, a last cathode, and intermediate cathodes,

a reset cathode positioned adjacent to and ahead of the first cathode in said series for use in starting a scanning cycle for said series of cathodes,

an anode electrode disposed on said face plate overlying said series of cathodes,

conductors connected to said cathodes and connecting said cathodes in groups with a single common conductor connected to each such group,

a separate cathode driver connected to each common conductor for energizing each cathode in turn along said series of cathodes,

a reset cathode driver connected to said reset cathode and adapted to be energized first before said separate cathode drivers in a cathode scanning cycle,

an anode driver connected to said anode electrode for applying operating potential thereto, and

a circuit coupled to said anode driver including a signal comparator circuit having a single output connected to said anode driver, said comparator circuit having two inputs, one input comprising a source of a sawtooth voltage, and the second input comprising a source of an analog signal to be represented in said panel by a bar of light made up of a group of energized cathodes, said cathode drivers continually energizing said cathodes in said series and causing said cathodes to exhibit cathode glow as long as there is an output from said comparator and said anode driver is energized thereby and energizes said anode.