JPS61104221A - System for driving car instruments - Google Patents

Abstract

PURPOSE:To realize the miniaturization and cost reduction of an apparatus, by driving an instrument, which displays information by the mechanical displacement of an indicator, by a pulse width modulation signal. CONSTITUTION:In a driver seat terminal 1, the digital signal sent from the other terminal (not shown in the drawing) in a car through a transmission line 3 is received by a transmitting and receiving circuit 4 to drive the indicator type instrument M of an instrument panel. Instruments M-1-M-n are connected to a drive power source and switching circuit 10-1-10-n and a constant current equal to or more than rated full scale is cyclically and intermittently flowed over a time shorter than the mechanical response time of each instrument. The switching circuits 10-1-10-n are turned ON or OFF by flip-flops 9-1-9-n set or reset in the duty ratio corresponding to the input digital value by a microprocessor 7. By this method, a D/A converter is dispensed with and the miniaturization and cost reduction of the apparatus can be realized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a driving system for automobile instruments, and in particular to a method for transmitting digitally converted sensor data for multiplex transmission etc. to a pointer-type instrument that displays the operating status of the automobile. Concerning the drive method of the output instrument.

[Conventional technology]

In recent years, in order to simplify the electrical wiring in automobiles, which has become increasingly complex, and to reduce the amount of wiring, multiple terminal devices connected to each other by transmission lines are distributed within the vehicle, and each terminal device is At the same time, each local switch or sensor transmits information to the transmission line.

A digital multiplex transmission device is being considered that receives and processes information transmitted by other terminal devices and outputs the processed information to local electrical equipment.

By the way, in a car, there are some pieces of information that are appropriate to convey to the driver in quantity. for example.

These include engine rotational speed, remaining amount of fuel, and temperature of engine cooling water. Pointer-shaped instruments, which have excellent intuitive visibility, are still commonly used as means for outputting this information.

FIG. 2 is a block diagram showing an example of a conventional configuration of a driving status display system placed in a driver's seat among a plurality of terminals distributed in a vehicle in order to realize the above idea. The operation status display system includes a driver's seat/terminal 1, an instrument panel 2 for displaying information necessary for driving the vehicle to the driver. Terminals installed elsewhere in the vehicle (
(not shown) for transmitting and receiving information.

The driver's seat terminal 1 includes a transmitting/receiving circuit 4 connected to the transmission path 3 for transmitting and receiving time-division multiplexed information, and a D/R circuit provided independently corresponding to the number n of information to be output to the pointer-shaped instrument.
A conversion circuits 5-1 to 5-n, and D/A conversion circuits 5-1 to 5-n.
A linear amplification circuit 6-1 to 6-n for amplifying the output signal of 5-n and driving each instrument, a microprocessor 7 for controlling each circuit inside the operation terminal l, and data to the microprocessor 7. The microprocessor 7 is provided with a pass line 8 and the like for transferring commands from the microprocessor 7 and the like. Also,
The instrument panel 2 is provided with pointer-shaped instruments M-1 to M-n for displaying information to the driver, and is driven by the linear amplifier circuits 6-1 to 6-n. Pointer type instrument M-1~
M-n is an instrument, such as an engine tachometer, a fuel level gauge, a cooling water temperature gauge, etc., which displays information using its pointer.

In reality, the driver's seat terminal 1 includes a digital output circuit for driving various display lamps on the instrument panel 2, and a digital input circuit that takes in switch information near the driver's seat in order to send it to other terminals. is incorporated, but since it is not related to the essence of this invention, illustration is omitted.

At the end of the transmission line 3, a front terminal (not shown) installed at the front of the vehicle, for example, receives an analog signal input from an engine coolant temperature sensor and an ignition pulse sensor to check the engine speed. cycle information etc.
Similarly, a rear terminal located at the rear of the vehicle, for example, digitally encodes analog signals from the fuel amount sensor and transmits the signals.

The driver's seat terminal 1 receives the above-mentioned digitized signal by the transmitting/receiving circuit 4, and after the microprocessor 7 reads it, for example, if the information is to be output to the instrument M-1, the D/
Like the A conversion circuit 5-1, the received digitized information is sorted and distributed to the D/A conversion circuits 5-1 to 5-n corresponding to the systems of instruments to be output. The D/A conversion circuits S-t to 5-n each convert the digital information transferred from the microprocessor 7 into an analog signal. Instruments cannot be driven directly;
Furthermore, pointer-shaped instruments M-1 to M-n on the instrument panel are driven via linear amplifier circuits 6-1 to 6-n.

[Problem that the invention seeks to solve]

However, the conventional automobile driving situation display system described above transfers digitally encoded information to the D/A converter 5-
1 to 5-n, return to analog signal, pointer type instrument M
-1 to M-n, D/A conversion circuit 5-1
5-n and linear amplifiers 6-1 to 6-n are required, resulting in a problem that one circuit configuration becomes complicated.

The present invention has been made in view of the above points.

It is an object of the present invention to provide a driving method for an automobile meter having a pointer-type meter driving function equivalent to that of the conventional example described above, using a simple circuit.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides an automobile operation status display system that displays information indicating the operation status of the automobile using a type of meter that expresses information by mechanical deviation of a pointer. A meter driving means is provided which periodically supplies a driving current of a constant value equal to or exceeding the rated full scale in a period shorter than the mechanical response time of the pointer-type meter, and The pointer-type instrument is driven by changing the duration of the driving current in accordance with the amount by which the pointer of the pointer-type instrument is to be shifted.

(Function) By driving the automobile pointer-type instrument as described above, there is no need for an A/D conversion circuit or a linear amplifier circuit as shown in the conventional example, and the automobile pointer-type instrument can be driven with a simple digital circuit. It becomes possible to drive.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing the configuration of a driving status display system to which the automobile instrument drive method according to the present invention is applied. In this figure, parts given the same reference numerals as those in FIG. 2 indicate the same or equivalent parts. 9-1 to 9-n are flip-flops provided corresponding to n instrument systems, each with 7 flip-flops.

It is configured so that it can be arbitrarily set or reset from the microprocessor 7 through the pass line 8. (
These flip-flops 9-1 to 9-n may be input/output ports built into the microprocessor 7. )
10-1 to 10-n are the flip-flops 9-1 to 9-
a switching circuit that is turned on or off by the output of n;
RV-1 to RV-n are variable resistors TR-]-TR-n
is a transistor.

FIG. 3 is a diagram illustrating the characteristics of the pointer-type instrument used in the above-mentioned operation status display system, in which A is the drive current for the instrument, B is the instruction operation of the pointer-type instrument corresponding to the drive current A, and C is the intermittent periodic point of the drive current A at which the vibration of the pointer of the pointer-type instrument is no longer recognized (hereinafter this is referred to as the "vibration critical point"). Fig. 4 is a diagram showing the energization time width W of the driving current, with the intermittent period T = T I of the vibration critical point C being constant, and Fig. 5 is the meter for the energization rate W/T 1 of the driving current. 3 is a graph showing the relationship between the amount of deviation of the guideline.

In FIG. 3, as the intermittent period T of the meter drive current A is gradually shortened, the pointer of the meter finally becomes unable to respond and becomes stationary. The intermittent period T1 of the drive current A at this vibration critical point C is about 1 second for thermal distortion instruments used for slow operation, such as fuel level gauges and cooling water temperature gauges.
Due to the need for fast dissolution and wide range indications at certain engine speeds, the time required for movable ring type meters is approximately 20 milliseconds. Further, as shown in the graph of FIG. 5, the driving current whose intermittent cycle is constant as the above TI,
By appropriately changing the ID conduction rate W/T1.

Any instrument pointer deviation can be obtained. At this time.

If the meter pointer is intentionally set to be at full scale when the energization rate W/T I is, for example, 95%, an overscale state of the pointer can also be expressed.

The graph in FIG. 5 also shows this situation.

The operation of the operation status display system shown in FIG. 1 will be explained based on the above-mentioned characteristics of the pointer-shaped instrument. The conventional configuration shown in FIG. 2 is such that the driver's seat terminal 1 reads digitized information such as cooling water temperature, engine rotation period, remaining fuel amount, etc. from the transmission line 3 through the transmission/reception circuit 4 into the microprocessor 7. This is exactly the same as explained in the example. The microprocessor 7 in FIG. 1 always sets each of the flip-flops 9-1 to 9-n at a constant cycle, and from the time of setting, if the information is to be output to a pointer-type meter M-1, the flip-flops are set. The microprocessor 7 measures the time corresponding to the size of the digital information being read for each output system, such as finding the timing to reset the output system 9-1, and as soon as that time is reached,
Reset the flip-flop of the applicable instrument system.

The set side output of each flip-flop 9-1 to 9-n is
Resistors R-1 to R-n and transistors TR-1 to T
Switching circuits 10-1 to 10-n each comprising R-n control energization of meters M-1 to M-n, respectively. That is, a constant value of current is applied to the meter only while the flip-flop is set, and this is repeated permanently. Here, the fixed cycle for setting the flip-flops 9-1 to 9-n is set to a time shorter than the intermittent cycle TI of the vibration critical point C explained in FIG. The energization time W such that the relationship between the deviation of the meter and the energization rate corresponds to that shown in the graph of Fig. 5.
By making it match the current value, it is possible to arbitrarily bias the pointer of the meter simply by intermittent control of a constant current value. Note that the variable resistor RV-1=RV-n is for adjusting the full scale of each pointer-shaped meter.

By the way, in a pointer-type instrument where the cycle T1 of the vibration critical point C is short and high indicating resolution is required, such as the engine revolution meter mentioned in the explanation of FIG. 3, the microprocessor 7 controls the flip-flop. In order to generate the timing to reset, it is necessary to operate on an extremely short time base.

For example, if a pointer-shaped instrument with a period Tl of the vibration critical point C of 20 milliseconds is used and an indication resolution of 200 equal parts is required, a flip-flop reset using a time shorter than 100 microseconds as a unit time. , which significantly reduces the overall processing capacity of the microprocessor 7.

FIG. 6 is a diagram showing a second embodiment of the present invention that solves this problem, and is a diagram showing the flip-flop and subsequent parts of one instrument system. In the figure, Figures 1 and 2
Portions with the same reference numerals as those in the drawings indicate the same or equivalent portions. In the figure, 11 is a clock pulse, 12 is an auxiliary counter,
13 is a count end pulse outputted by the auxiliary counter 12.

In Figure 6, although not shown in the figure, the first
As in the case shown in the figure, the microprocessor 7 sets the flip-flop 9 through the pass line 8, and subsequently writes the energization time data for driving the pointer-shaped instruments of the system into the auxiliary counter 12. , a clock pulse 11 with a shorter period than the time base corresponding to the required resolution is given, and the auxiliary counter 1
The clock pulse 11 sequentially subtracts the data written into the counter 2, and when the result reaches zero, the flip-flop 9 is automatically reset by the count end pulse 13. There is no difference from the first embodiment shown in FIG. 1 in that the energization of the meter is controlled by the output of the flip-flop 9. Therefore, the microprocessor 7 has, for example, 20
At regular intervals such as milliseconds, the flip-flop 9 is set, and the quotient obtained by dividing the energization time width W required to bias the instrument pointer at that point by the period of the clock pulse 11 is sent to the auxiliary counter 12. Since only writing is required, the load on the microprocessor 7 is greatly reduced.

The first embodiment uses a slow-responsive instrument.
.

For applications that do not require high indication resolution, or for secondary
The embodiment is suitable for the opposite case.

〔Effect of the invention〕

As described above in detail, according to the present invention.

Meter drive means for periodically passing and intermittent driving current of a constant value equal to or exceeding the rated full scale of the pointer-type meter in a time shorter than the mechanical response time of the pointer-type meter; Since the time width of the drive current is changed according to the amount by which the pointer of the pointer-shaped instrument is to be biased, the conventional D/A conversion circuit and linear amplification circuit are not required, and a purely digital circuit is used. It can be composed of 1
The circuit becomes simpler, and extremely excellent effects can be obtained in reducing the size and cost of the device.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a driving status display system to which the driving method of an automobile instrument according to the present invention is applied;
The figure is a block diagram showing the configuration of a conventional operation status display system, Figure 3 is a diagram for explaining the characteristics of a pointer-type instrument, and Figure 4 is the intermittent cycle of the vibration critical point of the pointer-type instrument and the energization of drive current. FIG. 5 is a diagram showing the time width, FIG. 5 is a diagram showing the relationship between the energization rate of the drive current and the deflection amount of the meter pointer, and FIG. 6 is a diagram showing another embodiment according to the present invention. In the diagram, 1...driver's seat terminal, 2...-instrument panel, 3...
...Transmission line, 4... - Transmission/reception circuit, 8... Pass line, 9-1 to 9-n... Flip-flop, 10-1
~10-n...Switching circuit, 11...Clock pulse, 12...Auxiliary counter, 13...Count end pulse.

Claims (1)

[Claims] In a vehicle operation status display system that displays information indicating the vehicle operation status using an instrument shaped like a mechanical deflection of a pointer, the pointer-shaped instrument is configured to have a pointer-shaped instrument at or above its rated full scale. A meter driving means is provided which periodically supplies a constant value of driving current intermittently at a constant time shorter than the mechanical response time of the pointer-shaped meter, and the time width of the driving current from the meter driving means is set as above. A driving method for an automobile instrument characterized by driving a pointer-shaped instrument by changing the pointer of the needle-shaped instrument according to the amount by which the pointer is to be shifted.