Color-emitting DC level indicator

• US 4,388,589 A
• Filed: 06/23/1980
• Issued: 06/14/1983
• Est. Priority Date: 06/23/1980
• Status: Expired due to Term

• Current Assignee: Bernhard P. Molldrem Jr
• Original Assignee: Bernhard P. Molldrem Jr
• Inventors: Molldrem, Bernhard P. Jr.
• Primary Examiner(s): Karlsen, Ernest F.
• Application Number:
  US06/161,673
• Time in Patent Office: 1,086 Days
• Field of Search: 324/96, 324/122, 324/133, 340/366 R, 340/815.01, 340/815.03
• US Class Current: 324/96
• CPC Class Codes: G01R 13/404 for discontinuous display, i.e. display of discrete values analogue/digital conversion H03M1/00
• CPC Class Codes: G01R 19/16595 with multi level indication G01R19/16519 and G01R19/16533 take precedence

Abstract

A DC level indicator represents a sensed DC level by a color of emitted light. The indicator includes a plurality of lamps or LED'"'"'s, each emitting a respective primary color, and a current-feeding circuit supplying current to each of the lamps or LED'"'"'s when the sensed voltage level is in a respective predetermined subrange of the voltage range of the indicator. Preferably, the subranges overlap one another somewhat for at least some input levels and the indicator presents a complementary color for such levels. In one version, red, green, and blue lamps are driven by respective transistor switching circuits so that the voltage level is indicated by apparent spectral colors, from red, through orange, yellow, green, cyan, blue, and violet, to magenta as the voltage level sweeps from one end of the range to the other. In another version, an AC signal is mixed with the DC input level to form a mixed signal that is fed to a pair of LED'"'"'s, one red and one green, in an anti-parallel, or back-to-back arrangement. Here, as the DC level sweeps through the range, the indicator'"'"'s color changes from red, through orange and yellow, to green.

Claims

1. A DC level indicator wherein a sensed DC level of a particular polarity and within a particular range is indicated by the apparent color of light comprising

DC input means receiving said DC level within said particular range and having said particular polarity, said range having a plurality of subranges each smaller than said range;

color light generating means formed of a plurality of light emitting means, each radiating light of a respective primary color, and positioned together so that when more than one of said light emitting means emits light the resulting emitted light appears as a blend of the respective colors; and

drive means connected to said DC input means for supplying current to each of said light emitting means that varies in response to the received DC level so that each said light emitting means radiates its respective color light when said DC level is within a respective subrange, but substantially ceases to radiate when said DC level is outside said respective subrange but within said predetermined range and so that within an overlapping portion of said subranges two of said light emitting means emit their respective color light, said drive means being powered by voltage of said particular polarity.

2. A DC level indicator according to claim 1, wherein said subranges overlap at least in part, and at least two light emitting means cooperate to produce complementary-colored light when said DC level is in the overlapping portion of their respective subranges.

13. A DC level indicator according to claim 1, wherein when said DC level is within said overlapping portion, the proportion of the respective colors constituting said blend varies gradually with said DC level.

3. A DC level indicator wherein a sensed DC level is indicated by the apparent color of light comprising

DC input means receiving said DC level within a range having a plurality of overlapping subranges;

color light generating means formed of first, second, and third light-emitting elements of respective first, second, and third primary colors, and positioned together so that the resulting emitted light appears as a blend of the respective primary colors; and

drive means coupled to said DC input means for supplying current to each of said light-emitting elements of said color light generating means, and operative to vary said current in response to the received DC level so that each said light emitting element radiates its respective color light when said DC level is in a respective subrange, but substantially ceases to radiate when said DC level is outside said respective subrange, including a first, a second, and a third switching circuit to switch said first, second, and third light-emitting elements on when said DC level is within said first, said second, and said third subrange, respectively, and to switch the respective elements off otherwise, two of said elements being switched on by their respective switching circuits in an overlapping portion of their respective subranges.

4. A DC level indicator according to claim 3, wherein at least one of said first, second, and third switching circuits includes a pair of complementary transistors each having current-conducting electrodes and a control electrode, connected with their current-carrying electrodes in series so that the current passing therethrough controls the radiation of light by the respective light emitting element, and with their control electrodes coupled to said DC input means;

and biasing means coupled to said control electrodes so that both of said transistors conduct when said DC level is within the respective subrange, but at least one thereof is rendered non-conductive outside the respective subrange.

5. A DC level indicator according to claim 4, wherein the respective subrange associated with said at least one switching circuit is divided into an upper and a lower part separated from one another, and said at least one switching circuit includes at least an additional transistor coupled to control the radiation of light by said respective light emitting element, and additional biasing means coupled between said DC input means and said additional transistor, so that the pair of transistors conduct when said DC level is in one of the upper and lower parts of said subrange, and the additional transistor conducts when said DC level is within the other part of said subrange.

6. A DC level indicator wherein a sensed DC level is indicated by the apparent color of light comprising

DC input means receiving said DC level within a range having a plurality of subranges;

color light generating means including a pair of back-to-back, oppositely-polarized LED'"'"'s emitting different respective primary colors, and positioned together so that when more than one such LED emits light the resulting emitted light appears as a blend of the respective colors; and

drive means coupled to said DC input means for supplying current to said LED'"'"'s as a function of the received DC level so that each said LED radiates its respective color light when said DC level is within a respective subrange but substantially ceases to radiates when said DC level is outside said respective subrange, and including mixing means for superimposing an AC signal on a DC signal corresponding to said DC level, to provide a resulting mixed signal to one end of said pair of LED'"'"'s, and bias means coupled to the other end of said pair of LED'"'"'s so that one only of said pair emits light of its color when said DC level is below a first voltage, the other only of said pair emits light of its color when said DC level is above a second voltage, and both LED'"'"'s of said pair emit light of their respective colors when said DC level is between said first and second voltages.

7. A DC level indicator according to claim 6, wherein said AC signal is provided at a sufficiently high frequency that, for any DC level between said first and second voltages, the light emitted by said pair of LED'"'"'s appears as a single color blended from said one and said other primary colors.

8. A DC level indicator according to claim 6, wherein said first voltage is determined by the difference between the level of said bias means and the level of said AC signal, while said second voltage is determined by the sum of the levels of said bias means and said AC signal.

9. A DC level indicator circuit to which a "tricolor" LED device, formed of back-to-back parallel LED'"'"'s of different colors of visible light, is to be connected, the device having a pair of terminals to which electrodes of said device are to be coupled;

comprising

means generating an AC signal;

means receiving an input DC voltage; and

drive means having an input coupled to said generating means and another input coupled to said receiving means for providing across said pair of terminals said AC signal with a DC component thereof governed in accordance with the received input DC voltage, such that the apparent color of light emanating from said LED device is substantially of one said color when said input DC voltage is below a first level, is substantially of the other, different color when said input DC voltage is above a second level, but when said input DC voltage is between said first and said second levels, said AC signal alternately switches said LED'"'"'s of said device on, so that the apparent color of light emanating therefrom is a blend of said colors.

10. A DC level indicator circuit according to claim 9, wherein said means generating said AC signal and said drive means are powered by a DC source of the same polarity as the input DC voltage.

11. A DC level indicator wherein a sensed DC level of a particular polarity is indicated by the apparent color of light comprising DC input means receiving said DC level within a range having a plurality of overlapping subranges;

color light generating means formed of first, second, and third light-emitting elements of a respective first, second, and third primary colors, and positioned together so that the resulting emitted light appears as a blend of the respective primary colors; and

drive means coupled to said DC input means for supplying current that varies in accordance with said DC level to each of said light-emitting elements of said color light generating means in response to the received DC level so that each said light-emitting element radiates its respective color light when said DC level is within a respective subrange, but substantially ceases to radiate when said DC level is outside said respective subrange but within said predetermined range, including a first, a second, and a third switching circuit powered by voltage of said particular polarity to switch said first, said second, and said third light-emitting elements on when said DC level is within said first, said second, and said third subrange, respectively, and to switch the respective elements off otherwise, two of said elements being switched on in an overlapping portion of their respective subranges.

12. A DC level indicator wherein a sensed DC level of a particular polarity is indicated by the apparent color of light comprising DC input means receiving said DC level within a range having a plurality of subranges;

color light generating means including a pair of back-to-back, oppositely polarized LED'"'"'s emitting different respective primary colors, and positioned together so that when more than one such LED emits light the resulting emitted light appears as a blend of the respective colors; and

drive means coupled to said DC input means and powered by voltage of said particular polarity for supplying current to said LED'"'"'s as a function of the received DC level so that each said LED radiates its respective color light when said DC level is within a respective subrange but substantially ceases to radiate when said DC level is outside its respective subrange, and including mixing means for superimposing an alternating signal on a DC signal corresponding to said DC level, to provide a resulting mixed signal to one end of said pair of LED'"'"'s, and bias means coupled to the other end of said pair of LED'"'"'s so that one only of said pair emits light of its color when said DC level is below a first voltage, the other only of said pair emits light of its color when said DC level is above a second voltage, and both LED'"'"'s of said pair emit light of their respective colors when said DC level is between said first and second voltages.