JPH1054736A - Sensor signal processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor signal processor reducing the current consumption and the heating of a sensor power supply. SOLUTION: This sensor signal processor is provided with a sensor power supply 11 feeding a current to a sensor mounted on a vehicle, an ADD converter 25 sampling a sensor output voltage outputted from the sensor at every prescribed time, and a power supply controller 21 controlling the sensor power supply 11 to feed the current to the sensor when the ADD converter 25 samples the sensor output voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor signal processing device for sampling a sensor signal from a sensor mounted on a vehicle and instructing the meter to instruct the meter. About.

[0002]

2. Description of the Related Art A vehicle such as an automobile is equipped with a fuel meter and a temperature meter, and a fuel sensor and a temperature sensor are also mounted in correspondence with these meters.

FIG. 6 shows an example of a fuel sensor. In FIG. 6, gasoline 53 is stored in a tank 51.
Is satisfied, and the float 5
5 moves up and down, and as the float 55 moves up and down, the sliding point P moves up and down, and the resistance value of the resistor 18 at the sliding point P changes.

The temperature sensor is, for example, a thermistor or the like, has a hyperbolic characteristic as shown in FIG. 7, and a resistance value changes with a change in temperature.

In this case, as shown in FIG. 5, on the meter side, a current is supplied from a sensor power supply 11 to a fuel sensor having a sensor resistor 17 (Rs) via a pull-up resistor 15 (R).

The output voltage Vs from the fuel sensor having the sensor resistance 17 (Rs) is converted into an analog / digital (A / D) signal provided in the microcomputer 19a.
The sampling is performed by the converter 25.

Further, according to the magnitude of the sampled sensor output voltage, the driving unit 27 operates the pointer 3 of the meter 29.
1 is rotated.

The resistance value of the sensor is about several ohms when the gasoline 53 is full, and is about several hundred ohms when the gasoline 53 is empty, and both have relatively low resistance. Also, the pull-up resistor 15 is set to about several tens of ohms to increase the change in the sensor output voltage Vs.

[0009]

However, the resistance value Rs of the sensor resistor 17 and the resistance value Rs of the pull-up resistor 15 are different.
Is relatively small, a considerably large current always flows from the sensor power supply 11. For this reason, the current consumption of the meter has increased.

In addition, the sensor power supply 11 generates a considerable amount of heat with an increase in current consumption, which necessitates the provision of a heat radiating plate, thereby increasing costs.

An object of the present invention is to provide a sensor signal processing device capable of reducing current consumption and heat generation of a sensor power supply.

[0012]

The sensor signal processing device of the present invention employs the following means to solve the above-mentioned problems. The invention according to claim 1 is a sensor power supply for supplying a current to a sensor mounted on a vehicle, a sampling unit for sampling a sensor output voltage output from the sensor at predetermined time intervals, and the sampling unit outputs the sensor output voltage. A power control unit that controls the sensor power so as to supply a current to the sensor at the time of sampling is provided.

According to the present invention, when the sampling section samples the sensor output voltage, the power supply control section controls the sensor power supply to supply a current to the sensor. That is, since current is supplied to the sensor every predetermined time, current consumption can be reduced and heat generated by the sensor power supply can be reduced.

According to a second aspect of the present invention, a switching element is provided between the sensor power supply and the sensor, and the power supply control section turns on the switching element when the sampling section samples a sensor output voltage. Is the gist.

According to the present invention, the power supply control section turns on the switching element when the sampling section samples the sensor output voltage, so that the current can be supplied from the sensor power supply to the sensor, and the current consumption can be reduced. The heat generation of the sensor power supply can be reduced as well as the heat generation.

In the invention according to claim 3, the power supply control section causes the sensor power supply to supply current to the sensor immediately before the sampling section samples the sensor output voltage, and the sampling section samples the sensor output voltage. Immediately thereafter, the current supply from the sensor power supply to the sensor is stopped.

According to the present invention, the power supply control section causes the sensor to supply current to the sensor from the sensor power supply immediately before the sampling section samples the sensor output voltage, and the sensor power supply from the sensor power supply immediately after the sampling section samples the sensor output voltage. Since the current supply to the sensor is stopped, the current flows reliably at the time of sampling, so that the sensor output voltage can be obtained accurately.

[0018] The invention of claim 4 is characterized in that it comprises a meter for indicating a sampling output voltage output from the sampling section.

According to the present invention, since the meter indicates the sampling output voltage output from the sampling section, the amount detected by the sensor can be ascertained.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the sensor signal processing device of the present invention will be described in detail with reference to the drawings.

<First Embodiment> FIG. 1 shows a configuration diagram of a sensor signal processing apparatus according to a first embodiment of the present invention. The sensor signal processing device shown in FIG. 1 is mounted on a vehicle such as an automobile,
It samples the sensor signal from the sensor and instructs the meter.

In FIG. 1, a sensor power supply 11 supplies current to a sensor, and the sensor power supply 11 is connected to an emitter of a switching transistor 13 for performing a switching operation. The sensor power supply 11 outputs an ignition (IGN) signal.

One end of a pull-up resistor 15 is connected to the collector of the switching transistor 13, and one end of a sensor resistor 17 is connected to the other end of the pull-up resistor 15.

The sensor resistance 17 is a resistance of a fuel sensor, a temperature sensor, or the like, and the resistance value changes according to the magnitude of the fuel value or the temperature value.

One end of the sensor resistor 17 is connected to a microcomputer 19. The microcomputer 19
It comprises a sampling signal generator 23, an A / D converter 25, and a power supply controller 21.

The sampling signal generator 23 outputs the sensor output voltage from the sensor resistor 17 every predetermined time (period T).
For example, a sampling signal for sampling every 100 ms is generated, and the sampling signal is
It outputs to the D converter 25 and the power supply control unit 21.

The A / D converter 25 receives the sampling signal from the sampling signal generator 23,
7 at predetermined time intervals, for example, 10
Sampling is performed every 0 ms, and the sensor output voltage, which is an analog signal, is converted into a digital signal.

The power supply control section 21 controls the sensor power supply 11 based on the sampling signal from the sampling signal generator 23 so as to supply current to the sensor when the A / D converter 25 samples the sensor output voltage. The sensor power control signal is generated.

The power control section 21 outputs a sensor power control signal to the base of the switching transistor 13,
When the A / D converter 25 samples the sensor output voltage, the switching transistor 13 is turned on.

Further, the power supply control section 21 causes the sensor power supply 11 to supply a current to the sensor immediately before the A / D converter 25 samples the sensor output voltage, based on the sensor power supply control signal. Immediately stops the current supply from the sensor power supply 11 to the sensor immediately after sampling the sensor output voltage.

The driving section 27 rotates the pointer 31 of the meter 29 in accordance with the magnitude of the sampling output voltage output from the A / D converter 25.

Next, Embodiment 1 configured as described above
The operation of the sensor signal processing device will be described in detail with reference to the timing chart shown in FIG. 2 and the flowchart shown in FIG.

First, as shown in FIG. 2, the sampling signal generator 23 generates pulses P11, P12.
Are sent to the power control unit 21, the power control unit 21 generates sensor power control signals having pulses P1, P2,... Having the same cycle T as the sampling signal T.

As shown in FIG. 2, for example, the sensor power supply control signal has a pulse P1 having a pulse width wider than a pulse width of a sampling signal pulse P11 and earlier than a sampling start time t2 by the sampling signal pulse P11. It is turned on (ON) at time t1.

The sensor power control signal is a sampling end time t3 by the pulse P11 of the sampling signal.
It turns off (OFF) at a later time t4.

Next, the power supply control section 21 determines whether or not the time has elapsed by a predetermined period T (step S11). That is, it is determined whether or not time has elapsed by the period T in order to sample the sensor output voltage every period T.

When the time has elapsed by the period T, the power supply control section 21 sends a sensor power supply control signal that is turned on at time t 1 to the base of the switching transistor 13. Then, since the switching transistor 13 is turned on, the sensor power supply 11 is turned on (step S1).
3).

Therefore, a current flows from the sensor power supply 11 to the sensor resistor 17 via the switching transistor 13 and the pull-up resistor 15.

When a current flows through the sensor resistor 17, a sensor output voltage is obtained from the sensor resistor 17, and the sensor output voltage is supplied to the A / D in the microcomputer 19.
Output to converter 25.

The A / D converter 25 has a sampling period T of the sampling signal from the sampling signal generator 23.
The sensor output voltage is sampled at the timing of the pulses P11, P12,.

When the sampling of the sensor output voltage from time t2 to time t3 is completed, the pulse P1 of the sensor power control signal is turned off at time t4. Therefore, the switching transistor 13 is turned off, so that the sensor power supply 11 is turned off (step S17).

As a result, the current supply from the sensor power supply 11 to the sensor resistor 17 via the switching transistor 13 and the pull-up resistor 15 is stopped.

Further, it is determined whether or not the process has been completed (step S19). If the process has not been completed, the process returns to step S11 to wait for the next pulse P2 to be turned on.

As described above, the power supply control section 21 turns on the switching transistor 13 only when the A / D converter 25 samples the sensor output voltage.

That is, since current is supplied to the sensor every predetermined time, current consumption can be reduced and heat generation of the sensor power supply can be reduced. Further, since the heat generated by the sensor power supply 11 can be reduced, it is not necessary to provide a special heat sink.

The power supply control unit 21 includes the A / D converter 2
5 causes the sensor power supply 11 to supply current to the sensor immediately before sampling the sensor output voltage, and the A / D converter 25
Stops the current supply from the sensor power supply 11 to the sensor immediately after sampling the sensor output voltage, so that the current flows reliably at the time of sampling, so that the sensor output voltage can be accurately obtained.

Further, since the pointer 31 of the meter 29 indicates the sampling output voltage output from the A / D converter 25, the amount detected by the sensor can be grasped.

In the first embodiment, the switching transistor 13 is provided outside the sensor power supply 11.
May be provided inside.

The sampling signal generator 23 is set to A /
Although provided outside the D converter 25, the sampling signal generator 23 may be provided inside the A / D converter 25.

<Second Embodiment> FIG. 4 shows a configuration diagram of a sensor signal processing device according to a second embodiment of the present invention. A feature of the sensor signal processing device shown in FIG. 4 is that a relay 14 is provided instead of the switching transistor 13 of the first embodiment shown in FIG.

One end a of the relay 14 is connected to the sensor power supply 11, and the other end b of the relay 14 is connected to one end of the pull-up resistor 15. The contact piece 14a is connected to the other end b by a sensor power control signal from the power control unit 21.

The other configuration of the second embodiment is the same as the configuration of the first embodiment, and the same portions are denoted by the same reference numerals, and detailed description thereof will be omitted.

Even in the sensor signal processing device having such a configuration, the power supply control section 21 turns on the relay 14 only when the A / D converter 25 samples the sensor output voltage.

That is, in the second embodiment, the same operation as in the first embodiment is performed, and the same effect as in the first embodiment can be obtained.

In the first embodiment, the bipolar switching transistor 1 is used as the switching element.
In the second embodiment, the relay 14 is used as the switching element. However, for example, a field-effect transistor or an analog switch may be used.

Although the relay 14 is provided outside the sensor power supply 11 in the second embodiment, for example, the relay 14 may be provided inside the sensor power supply 11.

[0057]

According to the present invention, when the sampling section samples the sensor output voltage, the power supply control section controls the sensor power supply to supply a current to the sensor. That is, since current is supplied to the sensor every predetermined time, current consumption can be reduced and heat generated by the sensor power supply can be reduced.

Further, since the power supply control section turns on the switching element when the sampling section samples the sensor output voltage, the current can be supplied from the sensor power supply to the sensor, and the current consumption can be reduced. Heat generation of the sensor power supply can be reduced.

The power supply control unit causes the sensor to supply current to the sensor from the sensor power supply immediately before the sampling unit samples the sensor output voltage, and supplies the current from the sensor power supply to the sensor immediately after the sampling unit samples the sensor output voltage. Is stopped, a current flows reliably during sampling, so that the sensor output voltage can be accurately obtained.

Further, since the meter indicates the sampling output voltage output from the sampling section, the amount detected by the sensor can be grasped.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a sensor signal processing device according to a first embodiment of the present invention.

FIG. 2 is a timing chart of each signal of the sensor signal processing device according to the first embodiment.

FIG. 3 is a flowchart illustrating an operation of the sensor signal processing device according to the first embodiment;

FIG. 4 is a configuration diagram illustrating a sensor signal processing device according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram showing a conventional sensor signal processing device.

FIG. 6 is a configuration diagram showing a fuel sensor.

FIG. 7 is a diagram illustrating characteristics of a temperature sensor.

[Explanation of symbols]

 Reference Signs List 11 sensor power supply 13 switching transistor 14 relay 15 pull-up resistor 17 sensor resistor 19 microcomputer 21 power supply controller 23 sampling signal generator 25 A / D converter 27 driver 29 meter 31 pointer 51 tank 53 gasoline 55 float

Claims (4)

[Claims] 1. A sensor power supply for supplying a current to a sensor mounted on a vehicle, a sampling unit for sampling a sensor output voltage output from the sensor at predetermined time intervals, and the sampling unit samples the sensor output voltage. A power supply control unit that controls the sensor power supply so as to sometimes supply a current to the sensor. 2. A switching element is provided between the sensor power supply and the sensor, and the power control unit turns on the switching element when the sampling unit samples a sensor output voltage. Item 2. The sensor signal processing device according to Item 1. 3. The power supply control section causes the sensor power supply to supply current to the sensor immediately before the sampling section samples the sensor output voltage, and the sensor power supply immediately after the sampling section samples the sensor output voltage. The sensor signal processing device according to claim 1 or 2, wherein current supply from the sensor to the sensor is stopped. 4. The sensor signal processing device according to claim 1, further comprising a meter for indicating a sampling output voltage output from the sampling unit.