Dual range speed indicator with acceleration display

Claim 2

A solid state speed indicator for use on railroad locomotives comprising: a display face; a first plurality of indicia arranged in an arc on said display face, said first plurality of indicia representing increments of speed; speed sensing means for controlling said first plurality of indicia to provide a display simulating an analog display of speed; a second plurality of indicia arranged on said display face in an arc of smaller radius but having a common center with the arc of said first plurality of indicia, said second plurality representing multiples of said increments of speed; a plurality of decimal numerals on said display face adjacent at least some of said indicia of the second plurality, said decimal numerals being in multiples of ten; an acceleration display on said display face providing an indication of acceleration or deceleration of said railroad locomotive; acceleration detecting means responsive to said speed sensing means for controlling said acceleration display; an overspeed indicator means on said display face providing a visual first indication of imminent overspeed conditions and a second indication of actual overspeed conditions; overspeed detecting means responsive to said speed sensing means for controlling said overspeed indicator; a planar LED for individually illuminating each of said decimal numerals; and range means for selectively controlling certain ones of said planar LEDs for selectively controlling the illumination of zeros in a units' position of said decimal numerals so as to provide said solid state speed indicator with two display ranges of speed.

Claim 3

The solid state speed indicator as recited in claim 1 further comprising: an odometer display providing an indication of distance traveled in feet; and distance computing means responsive to said speed sensing means for controlling said odometer display.

Claim 4

The solid state speed indicator as recited in claim 2 wherein said odometer display serves as said overspeed indicator for speeds above said predetermined level, said overspeed detecting means causing a flashing alpha display to appear on said odometer display as an indication of an imminent overspeed condition and a constant alpha display to appear as an indication of an actual overspeed condition.

Claim 5

The solid state speed indicator as recited in claim 1 wherein said overspeed indicator is in the form of a warning light, said overspeed detecting means causing said warning light to flash as an indication of an imminent overspeed condition and said warning light to be constantly on to appear as an indication of an actual overspeed condition.

Claim 6

The solid state speed indicator as recited in claim 1 wherein said first plurality of indicia, said second plurality of indicia, said plurality of decimal numerals, said acceleration display and said overspeed indicator are implemented with light emitting diodes, said solid state speed indicator further comprising a microcomputer responsive to said speed sensing means and generating control signals for controlling said light emitting diodes, said acceleration detecting means and said overspeed detecting means being implemented in a control program of said microcomputer.

Claim 7

The solid state speed indicator as recited in claim 1 wherein said first plurality of indicia, said second plurality of indicia, said plurality of decimal numerals, said acceleration display and said overspeed indicator are implemented with light emitting diodes, said solid state speed indicator further comprising: a plurality of light emitting diode driver integrated circuits, each of driver integrated circuits having an input for controlling the brightness of light emitting diodes connected to that driver integrated circuit; a plurality of current sinks each connected to a respective one of inputs of said driver integrated circuits; and a common brightness control means connected in parallel to said current sinks for simultaneously controlling the brightness of all said light emitting diodes.

Claim 8

The solid state speed indicator as recited in claim 6 wherein said current sinks are linearly-operated transistors having bases connected in parallel and said common brightness control means is a potentiometer for varying the base drive to said transistors.

Claim 9

The solid state speed indicator as recited in claim 6 wherein said current sinks are transistors having bases connected in parallel and said brightness control means switches said transistors on and off at a predetermined frequency and with a duty cycle that controls the brightness of said light emitting diodes.

Claim 10

The solid state speed indicator as recited in claim 6 wherein said first plurality of indicia are implemented with light emitting diodes, said solid state speed indicator further comprising: a plurality of light emitting diode driver integrated circuits, each of said driver integrated circuits having an internal voltage divider designed to control the turn-on threshold of each light emitting diode connected to that driver integrated circuit, said driver integrated circuit having a signal input connected to said internal voltage divider; and a low impedance, high precision resistive voltage divider having a plurality of taps across which said internal voltage divider of said driver integrated circuits are respectively connected, thereby ensuring high accuracy for the turn-on threshold for each light emitting diode in the arc of said first plurality of indicia.

Claim 11

A retrofit solid state speed indicator display for replacing meter movement displays on speed indicators used on railroad locomotives, said speed indicators having an equipment case housing electronic circuitry for driving said meter movement, said meter movement being mounted in a door serving as a closure for said equipment case, said retrofit display comprising: a display face mounted in a replacement door for the door in which said meter movement is mounted, said display face including a first plurality of indicia arranged in an arc, said first plurality of indicia representing increments of speed, a second plurality of indicia arranged in an arc of smaller radius but having a common center with the arc of said first plurality of indicia, said second plurality representing multiples of said increments of speed, a plurality of decimal numerals adjacent at least some of said indicia of the second plurality, said decimal numerals being in multiples of ten, an acceleration display providing an indication of acceleration or deceleration of said railroad locomotive, and an overspeed indicator providing a visual indication of both imminent and actual overspeed conditions; and a control circuit board attached to said replacement door responsive to a speed signal from said electronic circuitry in said case for controlling said first plurality of indicia to provide a display simulating an analog display of speed, said control circuit board further including acceleration detecting means responsive to said speed signal for controlling said acceleration display and overspeed detecting means responsive to said speed signal for controlling said overspeed indicator.

Claim 12

A retrofit solid state speed indicator display for replacing meter movement displays on speed indicators used on railroad locomotives, said speed indicators having an equipment case housing electronic circuitry for driving said meter movement, said meter movement being mounted in a door serving as a closure for said equipment case, said retrofit display comprising: a display face mounted in a replacement door for the door in which said meter movement is mounted, said display face including a first plurality of indicia arranged in an arc, said first plurality of indicia representing increments of speed, a second plurality of indicia arranged in an arc of smaller radius but having a common center with the arc of said first plurality of indicia, said second plurality representing multiples of said increments of speed, a plurality of decimal numerals adjacent at least some of said indicia of the second plurality, said decimal numerals being in multiples of ten, an acceleration display providing an indication of acceleration or deceleration of said railroad locomotive, and an overspeed indicator providing a visual indication of both imminent and actual overspeed conditions; and a control circuit board attached to said replacement door responsive to a speed signal from said electronic circuitry in said case for controlling said first plurality of indicia to provide a display simulating an analog display of speed, said control circuit board further including acceleration detecting means responsive to said speed signal for controlling said acceleration display and overspeed detecting means responsive to said speed signal for controlling said overspeed indicator.

Claim 13

The solid state speed indicator as recited in claim 10 wherein said acceleration display is in the form of an upwardly pointing arrow and a downwardly pointing arrow providing an indication of acceleration and deceleration, respectively, and wherein said overspeed indicator is in the form of a warning light, said overspeed detecting means causing said warning light to flash as an indication of an imminent overspeed condition and said warning light to be constantly on to appear as an indication of an actual overspeed condition.

Claim 14

The solid state speed indicator as recited in claim 10 wherein said first plurality of indicia, said second plurality of indicia, said plurality of decimal numerals, said acceleration display and said overspeed indicator are implemented with light emitting diodes, said solid state speed indicator further comprising: a plurality of light emitting diode driver integrated circuits, each of driver integrated circuits having an input for controlling the brightness of light emitting diodes connected to that driver integrated circuit; a plurality of current sinks each connected to a respective one of inputs of said driver integrated circuits; and a common brightness control means connected in parallel to said current sinks for simultaneously controlling the brightness of all said light emitting diodes.

Claim 15

The solid state speed indicator as recited in claim 10 wherein said first plurality of indicia are implemented with light emitting diodes, said solid state speed indicator further comprising: a plurality of light emitting diode driver integrated circuits, each of said driver integrated circuits having an internal voltage divider designed to control the turn-on threshold of each light emitting diode connected to that driver integrated circuit, said driver integrated circuit having a signal input connected to said internal voltage divider; and a low impedance, high precision resistive voltage divider having a plurality of taps across which said internal voltage dividers of said driver integrated circuits are respectively connected, thereby ensuring high accuracy for the turn-on threshold for each light emitting diode in the arc of said first plurality of indicia.

Claim 16

A solid state speed indicator for use on railroad locomotives comprising: a display face; a first plurality of indicia arranged in an arc on said display face, said first plurality of indicia representing increments of speed; speed sensing means for controlling said first plurality of indicia to provide a display simulating an analog display of speed; a second plurality of indicia arranged on said display face in an arc of smaller radius but having a common center with the arc of said first plurality of indicia, said second plurality representing multiples of said increments of speed; a plurality of decimal numerals on said display face adjacent at least some of said indicia of the second plurality, said decimal numerals being in multiples of ten; an acceleration display in the form of an upwardly pointing arrow and a downwardly pointing arrow providing an indication of acceleration and deceleration, respectively, acceleration detecting means responsive to said speed sensing means for controlling said acceleration display; an overspeed indicator on said display face providing a visual indication of both imminent and actual overspeed conditions; and overspeed detecting means responsive to said speed sensing means for controlling said overspeed indicator.

Claim 17

A solid state speed indicator for use on railroad locomotives comprising: a display face; a first plurality of indicia arranged in an arc on said display face, said first plurality of indicia representing increments of speed; speed sensing means for controlling said first plurality of indicia to provide a display simulating an analog display of speed; a second plurality of indicia arranged on said display face in an arc of smaller radius but having a common center with the arc of said first plurality of indicia, said second plurality representing multiples of said increments of speed; a plurality of decimal numerals on said display face adjacent at least some of said indicia of the second plurality, said decimal numerals being in multiples of ten; an acceleration display in the form of an upwardly pointing arrow and a downwardly pointing arrow providing an indication of acceleration and deceleration, respectively, acceleration detecting means responsive to said speed sensing means for controlling said acceleration display; an overspeed indicator on said display face providing a visual indication of both imminent and actual overspeed conditions; and overspeed detecting means responsive to said speed sensing means for controlling said overspeed indicator.

Claim 18

A solid state speed indicator for use on railroad locomotives comprising: a display face; a first plurality of indicia arranged in an arc on said display face, said first plurality of indicia representing increments of speed; speed sensing means for controlling said first plurality of indicia to provide a display simulating an analog display of speed; a second plurality of indicia arranged on said display face in an arc of smaller radius but having a common center with the arc of said first plurality of indicia, said second plurality representing multiples of said increments of speed; a plurality of decimal numerals on said display face adjacent at least some of said indicia of the second plurality, said decimal numerals being in multiples of ten; an acceleration display on said display face providing an indication of acceleration or deceleration of said railroad locomotive; acceleration detecting means responsive to said speed sensing means for controlling said acceleration display; an overspeed indicator on said display face providing a visual indication of both imminent and actual overspeed conditions; overspeed detecting means responsive to said speed sensing means for controlling said overspeed indicator; and said first plurality of indicia, said second plurality of indicia, said plurality of decimal numerals, said acceleration display and said overspeed indicator all implemented with light emitting diodes in said display face and said display face is mounted on an equipment case door, said door being substituted for a similar door carrying a meter movement display for an existing speed indicator device, thereby providing a retrofit solid state display having a higher reliability and accuracy than the meter movement display.

Claim 19

A solid state speed indicator for use on railroad locomotives comprising: a display face; a first plurality of indicia arranged in an arc on said display face, said first plurality of indicia representing increments of speed; speed sensing means for controlling said first plurality of indicia to provide a display simulating an analog display of speed; a second plurality of indicia arranged on said display face in an arc of smaller radius but having a common center with the arc of said first plurality of indicia, said second plurality representing multiples of said increments of speed; a plurality of decimal numerals on said display face adjacent at least some of said indicia of the second plurality, said decimal numerals being in multiples of ten; an acceleration display on said display face providing an indication of acceleration or deceleration of said railroad locomotive; acceleration detecting means responsive to said speed sensing means for controlling said acceleration display; an overspeed indicator on said display face providing a visual indication of both imminent and actual overspeed conditions; overspeed detecting means responsive to said speed sensing means for controlling said overspeed indicator; and said first plurality of indicia, said second plurality of indicia, said plurality of decimal numerals, said acceleration display and said overspeed indicator all implemented with light emitting diodes in said display face and said display face is mounted on an equipment case door, said door being substituted for a similar door carrying a meter movement display for an existing speed indicator device, thereby providing a retrofit solid state display having a higher reliability and accuracy than the meter movement display.