Multiple-meter driving apparatus

• US 5,446,655 A
• Filed: 02/21/1995
• Issued: 08/29/1995
• Est. Priority Date: 08/28/1991
• Status: Expired due to Fees

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Fukuda, Kazuyuki, Murase, Hiroshi
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): PARK, COLLIN
• Application Number:
  US08/391,467
• Time in Patent Office: 189 Days
• Field of Search: 364/424.01, 364/424.03, 364/550, 364/556, 364/424.04, 340/870.19, 340/870.21, 340/870.02, 340/870.03, 340/870.11, 340/870.13, 340/870.14, 340/825.1, 340/825.11, 340/438, 340/459, 340/461, 324/76.39, 324/114, 324/140 R, 324/143
• US Class Current: 701/1
• CPC Class Codes: G01D 21/02 Measuring two or more variables by means not covered by a single other subclass
• CPC Class Codes: G01R 19/25 using digital measurement techniques

Abstract

A multiple-meter driving system intends to cut down on the amount of space needed and to reduce the manufacturing cost by providing a single controller including a processing circuit, the controller being adapted collectively to drive a plurality of meters mounted in a vehicle such as motorcar or the like. Pulse signals each having a frequency corresponding to an input signal from a vehicle speed sensor or the like in the vehicle are counted with respect to their period T by a plurality of counters. The counts are then supplied to the controller. DC signals each corresponding to an input from a fuel sensor or the like are converted into digital signals by an A/D converter, which are also supplied to the controller. The processing circuit in the controller time-shares these input signals so as to perform operations of 1/T, sine and cosine. The results are again supplied back to the controller which in turn directs them to pulse width modulating circuits corresponding to the respective meters to be indicated. Since the respective meters are driven on a time-sharing basis, the single controller including the processing circuit can drive the meters collectively.

Claims

1. A multiple-meter driving apparatus comprising:

(a) a plurality of counter means, each counter means for receiving a pulse signal having a frequency corresponding to a first type of input from a first-type sensor, counting a period T of said pulse signal, and outputting a period signal;

(b) A/D converter means for receiving a DC signal corresponding to a second type of input from a second-type sensor and converting said DC signal into a digital signal;

(c) control means for sequentially inputting, during each predetermined time-sharing interval, the period signal from each of said plurality of counter means and said digital signal from said A/D converter means, said control means including processing means for time-share processing each of said input signals input exactly once during the predetermined time-sharing interval to form a corresponding meter angle signal and sequentially outputting the meter angle signal corresponding to each of said input signals; and

(d) drive means for sequentially receiving the meter angle signals during the predetermined time interval and driving a plurality of meters based on the meter angle signals outputted from said control means during the predetermined time interval, each meter angle signal driving a corresponding one of the plurality of meters.

2. A multiple-meter driving apparatus as defined in claim 1, wherein said first type of input represents at least one of a speed of a vehicle and a rotational speed of an engine, and said second type of input represents at least one of a residual fuel quantity and a cooling water temperature of the vehicle.

3. A multiple-meter driving apparatus as defined in claim 1, wherein said processing means comprises:

a first low-pass filter for removing high-frequency components in the period signals output from said plurality of counter means;

a second low-pass filter for removing high-frequency components in the digital signal outputted from said A/D converter means;

a 1/T operator for calculating and outputting an inverse period signal from the period signal output from said first low-pass filter;

an amplifier for amplifying one of the inverse period signal of said 1/T operator and said filtered digital signal output by second low-pass filter with a given gain;

a sine operator for calculating a sine component of the signal from said amplifier to form a sine signal and outputting said sine signal to said control means; and

a cosine operator for calculating a cosine component of the signal from said amplifier to form a cosine signal and outputting said cosine signal to said control means.

4. A multiple-meter driving apparatus as defined in claim 3, wherein said drive means comprises a plurality of driver circuits, each driver circuit comprising a modulating circuit and a driver, said modulating circuit modulating a pulse width of one of the meter angle signals corresponding to one of the period signals and the digital signal, said meter angle signal comprising the sine and cosine signals from said control means, the driver driving one of the plurality of meters based on the modulated signals from said modulating circuit.

5. A multiple-meter driving apparatus as defined in claim 4, wherein, during each predetermined time interval:

each of the plurality of period signals and the digital signal are input in sequence as a current input signal;

the input signal is processed by the control means to form corresponding sine and cosine signals; and

the sine and cosine signals corresponding to the current input signal are output to a corresponding one of the drive circuits, the drive circuit driving a gauge corresponding to the current input signal based on the corresponding sine and cosine signals.

6. A multiple-meter driving apparatus as defined in claim 1, wherein each first-type sensor comprises one of at least a vehicle speed sensor and an engine speed sensor.

7. A multiple-meter driving apparatus as defined in claim 1, wherein the second type sensor comprises one of at least a fuel amount sensor and an engine temperature sensor.

8. A multiple-meter driving apparatus as defined in claim 1, wherein the A/D converter means receives a plurality of the DC signals, each DC signal output from one of a plurality of second-type sensors, the A/D converter means converting one of the plurality of the DC signals at a time.

9. A time-sharing method for driving a plurality of meters using a multiple-meter driving apparatus, comprising the steps of:

(a) inputting pulse signals from at least one pulse type sensor;

(b) inputting DC signals from at least one DC-type sensor;

(d) converting each DC signal to a corresponding digital signal;

(e) inputting one of said period signals and digital signals as a current input signal;

(f) converting the current input signal to corresponding sine and cosine signals;

(g) outputting the sine and cosine signals corresponding to the current input signal to a corresponding one of a plurality of driving circuits, the corresponding driving circuit comprising a modulating circuit and a driver, the driver driving a corresponding meter;

(h) modulating the sine and cosine signals to form pulse width modulated signals;

(i) driving the corresponding meter in response to the pulse width modulated signals; and

(j) repeating steps (e)-(i) for each one of the period signals and digital signals, exactly once during a predetermined time-sharing interval.

10. The method of claim 9, wherein steps (a)-(j) are repeated for each of a plurality of the predetermined time intervals.

11. The method of claim 9, wherein the current input signal is a period signal.

12. The method of claim 11, wherein the current input signal converting step comprises the steps of:

filtering the current input signal;

determining an inverse period signal from the current input signal;

amplifying the inverse period signal;

determining the sine signal from the amplified signal; and

determining the cosine signal from the amplified signal.

13. The method of claim 9, wherein the current input signal is a digital signal.

14. The method of claim 13, wherein the current input signal converting step comprises the steps of

filtering the current input signal;

amplifying the filtered signal;

determining the sine signal from the amplified signal; and

determining the cosine signal from the amplified signal.