Continuously variable color optical device

• US 6,300,923 B1
• Filed: 07/06/1998
• Issued: 10/09/2001
• Est. Priority Date: 01/15/1986
• Status: Expired due to Fees

• Current Assignee: Texas Digital Systems, Inc. (NCR Voyix Corporation)
• Original Assignee: Texas Digital Systems, Inc. (NCR Voyix Corporation)
• Inventors: Havel, Karel
• Primary Examiner(s): Jankus, Almis R.
• Assistant Examiner(s): AWAD, AMR A
• Application Number:
  US09/109,948
• Time in Patent Office: 1,191 Days
• Field of Search: 345/82, 345/83, 345/150, 345/87-104, 313/500, 313/501, 324/96, 324/115, 257/89, 257/90
• US Class Current: 345/83
• CPC Class Codes: G01R 13/02 for displaying measured electric variables in digital form
• CPC Class Codes: G01R 13/26 Circuits for controlling the intensity of the electron beam or the colour of the display
• 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: G01R 15/125 for digital multimeters
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 3/14 Semiconductor devices, e.g. diodes

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.

Claims

1. A method for continuously controlling color of an optical device which includes a first light emitting diode for emitting, when forwardly biased, light signals of a first primary color, a second light emitting diode for emitting, when forwardly biased, light signals of a second primary color, and means for combining said light signals to obtain a light signal of a composite color, the method comprising:

repeatedly defining a cycle by developing a start signal at the beginning of each said cycle;

receiving n-bit data representing in value the portions of a first primary color, where n is an integer having value at least 2;

accumulating, in response to said start signal, a count proportional to the value of said data, and developing, when the count is accumulated, an end of count signal;

developing a true output and a complementary output, said true output being set in response to said start signal and reset in response to said end of count signal, and said complementary output being in the opposite condition;

coupling said true output for forwardly biasing said first light emitting diode, when said true output is in its set condition; and

coupling said complementary output for forwardly biasing said second light emitting diode, when said complementary output is in its set condition.

2. A method for continuously controlling color of an optical device which includes a first light emitting diode for emitting, when forwardly biased, light signals of a first primary color, a second light emitting diode for emitting, when forwardly biased, light signals of a second primary color, and means for combining said light signals to obtain a light signal of a composite color, the method comprising:

repeatedly developing a first start signal and a second start signal;

receiving first n-bit data representing in value the portions of a first primary color and second n-bit data representing in value the portions of a second primary color, where n is an integer having value at least 2;

accumulating, in response to said first start signal, a count proportional to the value of said first data, and developing, when the count is accumulated, a first end of count signal;

accumulating, in response to said second start signal, a count proportional to the value of said second data, and developing, when the count is accumulated, a second end of count signal;

developing a first bistable signal of a first logic level in response to said first start signal and a signal of another level in response to said first end of count signal;

developing a second bistable signal of a first logic level in response to said second start signal and a signal of another level in response to said second end of count signal;

forwardly biasing said first light emitting diode, in accordance with said first bistable signal of said first logic level; and

forwardly biasing said second light emitting diode, in accordance with said second bistable signal of said first logic level.

3. A variable color optical device comprising:

means for repeatedly defining a cycle by developing a start signal at the beginning of each said cycle;

input means for receiving n-bit data representing in value the portions of a first primary color, where n is an integer having value at least 2;

means for accumulating, in response to said start signal, a count proportional to the value of said data, and for developing, when the count is accumulated, an end of count signal;

a first light emitting diode for emitting, when forwardly biased, light signals of a first primary color, a second light emitting diode for emitting, when forwardly biased, light signals of a second primary color, and means for combining said light signals to obtain a light signal of a composite color;

bistable means including a true output and a complementary output, said true output being set in response to said start signal and reset in response to said end of count signal, and said complementary output being in the opposite condition;

first means for coupling said true output for forwardly biasing said first light emitting diode, when said true output is in its set condition; and

second means for coupling said complementary output for forwardly biasing said second light emitting diode, when said complementary output is in its set condition.

4. A variable color optical device comprising:

means for repeatedly developing a first start signal and a second start signal;

input means for receiving first n-bit data representing in value the portions of a first primary color and second n-bit data representing in value the portions of a second primary color, where n is an integer having value at least 2;

first means for accumulating, in response to said first start signal, a count proportional to the value of said first data, and for developing, when the count is accumulated, a first end of count signal;

second means for accumulating, in response to said second start signal, a count proportional to the value of said second data, and for developing, when the count is accumulated, a second end of count signal;

a first light emitting diode for emitting, when forwardly biased, light signals of a first primary color, a second light emitting diode for emitting, when forwardly biased, light signals of a second primary color, and means for combining said light signals to obtain a light signal of a composite color;

first bistable means for developing a signal of a first logic level in response to said first start signal and a signal of another level in response to said first end of count signal;

second bistable means for developing a signal of a first logic level in response to said second start signal and a signal of another level in response to said second end of count signal;

first means for forwardly biasing said first light emitting diode, in accordance with said signal of said first logic level developed by said first bistable means; and

second means for forwardly biasing said second light emitting diode, in accordance with said signal of said first logic level developed by said second bistable means.