Display unit of speedometer for automobile

• US 4,647,901 A
• Filed: 04/13/1983
• Issued: 03/03/1987
• Est. Priority Date: 04/20/1982
• Status: Expired due to Fees

• Current Assignee: Regie Nationale Des Usines Renault (Renault), Stanley Electric Company Limited
• Original Assignee: Regie Nationale Des Usines Renault (Renault), Stanley Electric Company Limited
• Inventors: Robert, Pierre H., Funaoka, Chihiro, Teshima, Tohru
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): Queen, Tyrone
• Application Number:
  US06/484,505
• Time in Patent Office: 1,420 Days
• Field of Search: 340/52 F, 340/52 R, 340/670, 340/62, 340/815.01, 340/753, 340/754, 340/709, 340/721, 340/722, 340/715, 324/115
• US Class Current: 340/461
• CPC Class Codes: B60K 35/60 Instruments characterised by their location or relative disposition in or on vehicles arrangements of lighting devices on dashboards B60Q3/10
• CPC Class Codes: G01P 1/10 for indicating predetermined speeds
• CPC Class Codes: G01P 1/103 by comparing the value of the measured signal with one or several reference values in general G01R17/00
• CPC Class Codes: G01R 13/406 representing measured value by a dot or a single line G01R13/408 takes precedence

Abstract

A display unit of a speedometer meter for an automobile, wherein a desired car speed is determined and an actual car speed is measured and signals corresponding thereto are applied to a comparing circuit and bar graph decoders. The comparing circuit compares the amplitude of the signals corresponding to desired car speed and actual car speed, and the bar graph decoders, after decoding the signals into a format compatible with a bar graph display, transmits the signals to an EX-OR circuit and an OR circuit. A selector circuit controlled by the output of a comparing circuit selects either the output of the EX-OR circuit or that of the OR circuit for driving plural segments of a bar graph display which accordingly displays both desired car speed and actual car speed either by driving selected display signals corresponding thereto or by driving display segments corresponding to a maximum value thereof and by inhibiting the driving of at least one display segment common to both desired car speed and actual car speed.

Claims

1. A display unit of a speedometer for an automobile, comprising:

a constant speed running circuit capable of producing output signals indicative of a desired car speed;

an actual car speed operational circuit capable of producing output signals indicative of actual car speed;

a comparing circuit for comparing the amplitudes of said output signals of said constant speed running operational circuit and said actual car speed operational circuit;

bar graph decoders receiving said output signals from said constant speed running operational circuit and said actual car speed operational circuit;

an EX-OR circuit having inputs coupled to respective bar graph decoders and having an output;

an OR circuit having inputs coupled to respective bar graph decoders and having an output;

selector means coupled to said output of said EX-OR circuit and said output of said OR circuit and controlled by an output of said comparing means for connecting a selected of said outputs of said EX-OR and OR circuits to an output of said selector means; and

a bar graph display comprising plural display segments and a driving circuit for activating selected of said segments, said driving circuit coupled to the output of said selector means such that said display segments are selectively driven by the output of said EX-OR circuit or the output of said OR circuit;

whereby said display device displays said desired car speed and actual car speed in two modes, including a first mode in which said display device displays desired car speed and actual car speed by selectively driving display segments corresponding thereto and a second mode in which said display device displays actual car speed and desired car speed by driving selected display segments corresponding to a maximum value of said actual car speed and said desired car speed and indicates at least one segment common to both said actual car speed and desired car speed by inhibiting driving of said at least one display segment.