초록 ▼

A firmware/hardware electronic digital speedometer connected to a vehicle multi-measurand data communications system maintains virtually no flicker in the display of digital numbers in a digital display unit such as a vacuum fluorescent display during movement of a vehicle when no change in speed is

A firmware/hardware electronic digital speedometer connected to a vehicle multi-measurand data communications system maintains virtually no flicker in the display of digital numbers in a digital display unit such as a vacuum fluorescent display during movement of a vehicle when no change in speed is apparent. A speed sensor supplies speed information to a first computing unit which establishes an accumulated count of speed during a first interval. Then the first computing unit supplies over a communications link the speed count to a second computing unit at a rate that approximates the update rate of the display unit. The second computing unit processes the speed data in a particular manner to effect the virtually flicker-free updating of the display and improved accuracy.

대표청구항 ▼

A firmware/hardware electronic digital speedometer used with a multi-measureand data communication system for measuring and then displayed vehicle speed as digital number values on a digital display unit having a predetermined update rate, the digital number values being derived from a series of ON

A firmware/hardware electronic digital speedometer used with a multi-measureand data communication system for measuring and then displayed vehicle speed as digital number values on a digital display unit having a predetermined update rate, the digital number values being derived from a series of ON and OFF ground switch closure signals in proportion to the distance traveled by a vehicle provided by a distance sensor unit coupled to a drive train of the vehicle, said system comprising: (a) first computing means connected to the distance sensor for receiving the switch closure signals, establishing a count of the number of switch closures occurring during a first time interval of series of such first time intervals as the vehicle moves and then converting each of said counts to a digital code of a chosen format at an end of each of the first time intervals, said digital code representing the number of counts per first time interval; (b) communication means including a communications link connected to said first computing means for sequentially sending each of said digital codes over said communications link at the end of each of the first time intervals at a sending rate substantially identical to the update rate of the display; (c) second computing means connected between said communication means and the display for receiving in a first register each of said digital codes sent over said communications link at the sending rate; for storing a next most recent digital code in a second register while a most recent digital code is being received by said first register; for multiplying by a first conversion factor a sum total number value of a number representation of said most recent digital code added to a number representation of said next most recent code to compute a speed number value to be displayed and for providing the display unit during a second time interval with the current computed speed number at a rate substantially identical with the update rate of the display until another most recent digital code is received by the first register during the next computation of the speed numbers; the summing of the digital codes being performed in a chosen manner to provide integer speed numbers, the integer speed numbers being supplied to the display unit in a manner that strikes a balance between updating the display unit slowly enough to make the displayed digital numbers readable and quickly enough to make the display unit responsive to changes in vehicle speed, the display of the speed numbers being kept suitably stable so that the digits in the display do not appear to indiscriminately jump around when no change in vehicle speed is apparent.