Tri-state function indicator
AssigneeDigital Equipment Corporation
InventorRandall A. White
Life of this patent
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Abstract
In order to indicate a function status which can be one of three states, upon detecting a first state, a bicolor LED is lighted with a first color; upon detecting a second state, the LED is lighted with a second color; and upon detecting a third state, the LED is alternately lighted with said first and said second colors at a sufficiently high rate to cause the color of the LED to appear as a third color.
Claims4
A method of indicating a function status which can be one of three function states, comprising upon detecting a first state, lighting a bicolor LED with a first color;
- upon detecting a second state, lighting the LED with a second color;
- and upon detecting a third state, alternately lighting said LED with said first and said second colors at a sufficiently high rate to cause the color of said LED to appear as a third color, said function states being indicated by a 2 bit binary code and further include:
- generating a first signal when both of said binary its are in a first binary state;
- coupling said first signal to the preset input of a D type flip flop;
- generating a second signal when a first of said binary signals is in a second state and a second of said binary signals is in said first state;
- coupling said second signal to the clear input of the D type flip flop;
- and generating a third signal when said second bit is in said second state;
- providing a clock oscillator having a clock signal;
- performing an And operation on said clock signal with said third signal;
- providing said clock signal as the clock input to a flip flop;
- coupling one of the outputs of said D type flip flop to its D input to alternate the outputs of the D type flip flop;
- using said first signal to energize the first color of said LED;
- using said second signal to energize the second color of said LED;
- utilizing said third signal by triggering said D-type flip flop to generate an alternating signal to alternately energize said first and second colors in said LED.
Apparatus for indicating a function status which can be one of three function states wherein said function states are indicated by a two bit binary code, comprising:
- means for detecting first, second and third states and providing as outputs first, second and third signals corresponding to said first, second and third states;
- means for generating said first signal when both of said binary bits are in a first state;
- means for generating said second signal when a first of said binary bits is in a second state and a second of said binary bits is in said first state;
- means for generating said third signal when said second bit is in said second state;
- a bicolor LED having a first cathode for a first color and a second cathode for a second color;
- means for coupling said first signal to said first cathode;
- means for coupling said second signal to said second cathode;
- a clock oscillator generating clock pulses;
- first means for Anding together said clock pulses with said third signal;
- a D-type flip flop having first and second outputs and trigger input;
- means for coupling said first signal to the preset input of said D type flip flop;
- means for coupling said second signal to the clear input of said D type flip flop;
- means for coupling one of the outputs of said D type flip flop to its D input to alternate the outputs of said D-type flip flop;
- means for coupling the outputs of said D-type flip flop respectively to the first and second cathodes of said LED;
- and
- means for coupling the output of said first means for Anding together to the trigger input of said flip flop to thereby alternately energize said first and second cathodes at a sufficiently high rate to cause the color of said LED to appear as a third color.
Dependencies are inferred from the claim text.