Abstract: A variable color optical device repeatedly develops a start signal and two end signals respectively timed in relation to the start signal in accordance with the values of two sets of data. Two stable signals are developed, each from the start signal to the respective end of signal. Two control signals are applied, in accordance with the two stable signals, for respectively forwardly biasing the light emitting diodes of two primary colors.

Abstract: A method for automatically evaluating the displayed value comprises the steps of receiving data for display, exhibiting a display indication of the data on a light emitting diode display area substantially surrounded by a variable color background area, comparing the value of the data with a limit, and controlling color of the background area in accordance with the result of the comparison. A display device for automatically evaluating the displayed value includes a light emitting diode display area substantially surrounded by a variable color background area and a device for receiving data for display and for exhibiting them on the display area. A comparator compares the value of the data with a limit and accordingly develops a comparison signal which is used to control the color of the background area to automatically indicate the significance of the displayed data.

Abstract: A single variable color display device simultaneously exhibits two distinct display units in a side by side relation. Two color controls are provided for illuminating the display units in respectively different colors so they could be readily distinguished.

Abstract: A multicolor display element includes a plurality of display areas arranged in a pattern. Each display area includes three light emitting diodes for emitting light signals of respectively different colors. The light emitting diodes of the same color are commonly coupled to three buses, respectively, which may be activated in selective combinations by a gate network, to illuminate the display areas in a selective blended color.

Abstract: A multicolor display element includes a plurality of display areas arranged in a pattern, each including light emitting diodes of respective primary colors, which are coupled to the buses in accordance with their colors. A single enable input is provided for receiving an enable signal having an active level and an inactive level, for selectively extinguishing the entire display element and for illuminating the selected display areas in a desired color. The enable input jointly controls the conductivity of tri-state buffers which are respectively coupled to the buses.

Abstract: A variable color complementary display device includes a plurality of display areas arranged in a pattern for selectively exhibiting a plurality of display units. Each display area includes a plurality of pairs of light emitting diodes for emitting, when forwardly biased, light signals of respective primary colors and a device for combining the light signals in the display area to obtain a light signal of a composite color. Each pair includes a first light emitting diode and a second light emitting diode, both of the same color, connected in an anti-parallel fashion such that their polarities are opposite. A device is provided for selectively forwardly biasing the first light emitting diodes, for illuminating certain of the display areas in a display color. The second light emitting diodes in the remaining display areas are automatically illuminated in a complementary color.

Abstract: A method for continuously controlling color of a display device comprises the steps of receiving three sets of data respectively representing the portions of three primary colors, accumulating three counts in accordance with the data, respectively, and setting three bistable devices for the respective durations of the accumulating. The outputs of the three bistable devices are coupled for respectively energizing three buses, to which the light emitting diodes of three primary colors are connected in accordance with their colors, for controlling the portions of the light signals of the primary colors emitted therefrom.

Abstract: A continuously variable color display system includes a plurality of display areas, each including three light emitting diodes, for emitting light signals of respectively different primary colors, which are controlled by three bistable devices, respectively. Each bistable device is set at the beginning of a time interval, defined by a corresponding input digital code, and reset at the end of the time interval. Accordingly, the light emitting diodes jointly illuminate in a composite color determined by three input digital codes.

Abstract: A variable color light emitting diode digital display system automatically exhibits integers and decimal numbers in different colors. A logic circuit is provided for detecting the presence or absence of a decimal point in a string of digits. The color of the exhibited digits is controlled in accordance with the detection.

Abstract: A multicolor multi-element display system includes a plurality of multicolor display elements, each having color control inputs for controlling its color and an enable input for controlling its condition. The color control signals are commonly presented to the interconnected color control inputs of all display elements. The individual display elements are independently illuminated or extinguished by enable control signals presented to their enable inputs.

Abstract: A light emitting diode display device includes a variable color display area, for exhibiting a selective display unit, substantially surrounded by a variable color background area. The light emitting diodes in the display area are commonly coupled to a plurality of display buses, in accordance with their display colors. Similarly, the light emitting diodes in the background area are commonly coupled to a plurality of background buses, in accordance with their background colors. A display color control is provided for selectively activating the display buses, for illuminating a desired display unit in a selective color. A background color control is further provided for activating the background buses, for illuminating the background area in a uniform color different from the color of the display area.

Abstract: A color control signal converter for converting a digital code to a color control signal includes a device for controlling the duration of pulses in accordance with the digital code, and a device for developing the color control signal in accordance with the duration of the pulses.

Abstract: A measuring system performs measurement of two measured values and simultaneously exhibits the two measurement results in a digital format on a single variable color display device in respectively different colors, in order to distinguish them comfortably.

Abstract: A variable color display systems sequentially exhibits digital values in a color in accordance with the relation of the presently exhibited digital value to a past digital value. A memory, controlled by a timer, is provided for storing data representing the past digital value. A comparator compares the presently exhibited digital value with the data stored in the memory and develops a comparison signal accordingly, which is then used to control the color of the presently exhibited digital value.

Abstract: A digital measuring device of the invention simultaneously exhibits the measured value of an analog signal, by digital indication, and its relation to an analog limit, by color of the digital indication. The measuring device includes an analog comparator, for comparing the value of the analog signal with the analog limit and for developing a comparison accordingly, and a digital measuring device, for converting the measured value of the analog signal to digital data, which are digitally exhibited on a variable color light emitting diode digital display device. The comparison signal is applied to a color control input of the display device, for controlling the color of the digital indication in accordance with the relation of the value of the analog signal to the analog limit.

Abstract: A variable color digital measuring system performs sequential tests and exhibits each measured value in a color in accordance with the previous measurement errors. An error memory is provided for storing a value indicating whether there was a measurement error. A color control illuminates the present measured value in a first color when the contents of the error memory indicate that there was no previous measurement error, and in a second color when the contents of the error memory indicate that there was a previous measurement error.

Abstract: A method of measuring, indicating, and automatically evaluating a measured value comprises the steps of measuring a signal, exhibiting a digital indication of the measured value of the signal on a multicolor light emitting diode display device that is substantially surrounded by a variable color background area, comparing the measured value with a limit to determine their relation, and controlling color of the background area accordingly, to simultaneously indicate the measured value of the signal, by the digital indication, and its significance, by color of the background area.

Abstract: A variable color digital measuring instrument sequentially exhibits measured values in a color in accordance with the relation of the present measured value to a past measured value. A memory, controlled by a timer, is provided for storing data representing the past measured value. A comparator compares the present measured value with the data stored in the memory and develops a comparison signal accordingly, which is then used to control the color of the presently exhibited measured value.

Abstract: A variable color display system exhibits a display unit in a color in accordance with the value of a limit. The color signals are developed in accordance with the value of the limit and applied to a color control input of the display system to control its color substantially continuously.

Abstract: A display device includes a display area, for exhibiting a display unit, substantially surrounded by a variable color background area, which includes a color control input for uniformly controlling its color. The variable color background area includes a plurality of multi-color light emitting diodes arranged in a pattern, which are coupled to the color control input for being illuminated in a selective uniform color in accordance with a color control signal.