JP2004198137A - Sensor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor device allowing cost reduction and simplification of a circuit structure by reducing the number of terminals. <P>SOLUTION: This sensor device 11 is connected to a D.C. power source at a power-side terminal 52. The sensor device 11 is provided with a magnetic sensor 55, a power IC 56, a switch circuit 57 and a switch control circuit 58, and all of them are connected to a load-side terminal 12 as a grounding side. The load-side terminal 12 is grounded through a brake lamp device 53. The magnetic sensor 55 is always supplied with a certain amount of power by the power IC 56. Thereby, an LED 53a of the lamp device 53 is supplied, through the magnetic sensor 55, with power to the level preventing it from functioning as a brake lamp when the switch circuit 57 is off. Power enough to light the brake lamp is supplied to the LED 53a when the switch circuit 57 is on. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sensor device, and more particularly, to a sensor device having a sensor that requires power supply.
[0002]
[Prior art]
Generally, a non-contact type sensor is configured to require power supply to detect a predetermined detection target. That is, for example, in the case of a magnetic sensor, the magnetic detection function is enabled based on the supply of electric power, and the magnetism of a magnetic material such as magnetized iron can be detected as a predetermined detection target. Therefore, a sensor device including a magnetic sensor is configured to include, for example, a power supply IC or the like as power control means for supplying power to the magnetic sensor. The sensor device includes a switch circuit that is connected to a power supply and a predetermined electric load and that is turned on when the magnetic sensor detects magnetism. That is, such a sensor device is configured to drive an electric load by turning on the switch circuit based on the magnetic detection of the magnetic sensor.
[0003]
Here, as shown in FIG. 2, a conventional sensor device 51 provided in an automobile and used for detecting the position of a brake pedal will be described. That is, the sensor device 51 is used to turn on a brake lamp as an electric load based on whether or not the brake pedal is operated.
[0004]
The sensor device 51 includes a power supply terminal 52 and a load terminal 54. The sensor device 51 is connected to a power supply (not shown) including a battery at a power supply terminal 52, and connected to a brake lamp device 53 at a load terminal 54. A fuse 59 that protects the sensor device 51 from overvoltage is provided in series between the power supply terminal 52 and the power supply. The sensor device 51 is configured to control the power supply of the brake lamp device 53.
[0005]
The brake lamp device 53 is provided with an LED 53a (light emitting diode) and a protection resistor 53b that are grounded on the minus side and serve as brake lamps. When power is supplied (a processing signal is output) from the sensor device 51 to the brake lamp device 53, a current flows through the LED 53a, and the LED 53a emits light. The protection resistor 53b is a resistor for protecting the LED 53a from overvoltage.
[0006]
Next, a specific configuration of the sensor device 51 will be described.
As shown in FIG. 2, the sensor device 51 includes a magnetic sensor 55, a power supply IC 56, the switch circuit 57, and a switch control circuit 58.
[0007]
The positive terminal of the magnetic sensor 55 is connected to the power supply terminal 52, and the negative terminal thereof is grounded via the ground terminal 61. Therefore, the magnetic sensor 55 is always supplied with electric power and is in a state where magnetism can be detected.
[0008]
The magnetic sensor 55 detects, for example, the magnetism of a bias magnet provided in the vicinity of the magnetic sensor 55 using, for example, an MRE (magnetic resistance element) or a Hall element. That is, although not shown, the magnetic sensor 55 is fixedly arranged at a predetermined location together with the bias magnet. On the other hand, a magnetic material is fixed to the brake pedal, and the magnetic material is displaced as the brake pedal is depressed.
[0009]
The magnetic body is arranged close to the magnetic sensor in a state where the brake pedal is not depressed (hereinafter referred to as a rest state). For this reason, the magnetic flux of the bias magnet is absorbed (induced) by the adjacent magnetic body in the rest state. On the other hand, the magnetic flux of the bias magnet is not absorbed (induced) by the magnetic material when the brake pedal is depressed and the magnetic material is separated from the magnetic sensor 55. Therefore, the sensor device 51 detects a different amount of magnetic flux between the rest state of the brake pedal and the state in which the brake pedal is depressed, and detects a larger amount of magnetic flux in the state in which the brake pedal is depressed than in the rest state. Has become. Therefore, the sensor device 51 sends out a detection signal having a higher output level when the brake pedal is depressed than when the brake device is in the rest state.
[0010]
Further, a sensor protection section 62 composed of a Zener diode for preventing an overvoltage from being applied to the magnetic sensor 55 is connected to the plus side terminal and the minus side terminal of the magnetic sensor 55 in parallel with the magnetic sensor 55. Therefore, when the voltage applied to the magnetic sensor 55 becomes an overvoltage and reaches the breakdown voltage value of the sensor protection unit 62, the Zener diode of the sensor protection unit 62 is short-circuited, and the voltage breakdown of the magnetic sensor 55 is prevented. Is prevented. A power supply IC 56 is connected in parallel with the magnetic sensor 55.
[0011]
The power supply IC 56 performs power control so that constant power is supplied to the magnetic sensor 55. The power supply IC 56 is connected at its positive terminal to the power supply terminal 52, and its negative terminal is grounded via a ground terminal 61. The power supply IC 56 is configured to detect a voltage applied to the magnetic sensor 55, and to supply power to the magnetic sensor 55 when a voltage drop occurs in the magnetic sensor 55. That is, the power supply IC 56 controls the magnetic sensor 55 so that a constant voltage equal to or higher than the voltage at which magnetism can be detected is applied.
[0012]
The switch control circuit 58 has a plus terminal connected to the power supply terminal 52 and a minus terminal connected to the ground terminal 61. The switch control circuit 58 is electrically connected to the magnetic sensor 55. The switch control circuit 58 receives a detection signal sent from the magnetic sensor 55, and amplifies the detection signal and a comparison circuit (both not shown) for comparing the amplified detection signal with a preset threshold value. Prepare. The signal output terminal of the switch control circuit 58 is connected to the gate of the switch circuit 57. As a result of the comparison by the comparison circuit, when the amplified detection signal is determined to be at the H level larger than the threshold value, the switch circuit The control signal is output to the gate 57. On the other hand, if the comparison circuit determines that the detection signal is at the L level smaller than the threshold, it does not output the control signal.
[0013]
That is, the switch control circuit 58 determines whether the brake pedal has been depressed by determining the magnitude of the detection signal based on the change in the amount of magnetic flux detected by the magnetic sensor 55. The switch control circuit 58 is configured to output a control signal by setting a detection signal input in a state where the brake pedal is depressed to an H level. Further, the switch control circuit 58 is configured so that the detection signal input in the sleep state is at the L level.
[0014]
The switch circuit 57 is an FET having a source S connected to the power supply terminal 52 and a drain D connected to the load terminal 54 in addition to the gate G. When a control signal is input to the gate G, the switch circuit 57 conducts between the source S and the drain D and turns on. As a result, the sensor device 51 short-circuits the power supply side terminal 52 and the load side terminal 54 via the switch circuit 57, and turns on the brake lamp device 53.
[0015]
As described above, the conventional sensor device 51 detects the position of the brake pedal based on the change in the amount of magnetic flux detected by the magnetic sensor 55, and when the switch control circuit 58 determines that the brake pedal is depressed, The switch circuit 57 is turned on, and the LED 53a of the brake lamp device 53 is turned on.
[0016]
[Problems to be solved by the invention]
However, since the sensor device 51 is configured to be supplied with power from a power supply and to supply power to the brake lamp device 53 when the switch circuit 57 is turned on, the sensor device 51 needs to include the power supply terminal 52 and the load terminal 54. Further, in addition to the above, it is necessary to include a ground terminal 61 for grounding the magnetic sensor 55, the power supply IC 56, and the switch control circuit 58 (hereinafter, sometimes referred to as the magnetic sensor 55) to which power is supplied. Therefore, the sensor device 51 has to be provided with three terminals in order to exhibit its function.
[0017]
On the other hand, a mechanical sensor device including a limit switch or the like, that is, a contact sensor device does not include the magnetic sensor 55 or the like that requires power supply. There is no need to provide the ground terminal. For this reason, the conventional non-contact sensor device 51 has a problem that the number of terminals increases as compared with the mechanical sensor device, and the manufacturing cost increases. Further, among traders, there has been a demand for a reduction in manufacturing cost and a simplification of a circuit configuration by reducing the number of terminals of the non-contact sensor device 51.
[0018]
Here, it is also conceivable that a magnetic sensor or the like supplied with power to reduce the number of terminals of the sensor device is grounded in common with an electric load such as the brake lamp device 53. However, while the sensor device is arranged near the operation target operated by the driver, the electric load such as the brake lamp device 53 is often arranged at a distance from the sensor device such as behind the vehicle. . Therefore, if the sensor device is to be grounded in common with the electric load, a relatively long harness (electric wire) extending from the front to the rear of the vehicle is required, which does not reduce the cost of the sensor device and simplify the circuit configuration. .
[0019]
The present invention has been made to solve the above problems, and an object of the present invention is to provide a sensor device capable of reducing costs and simplifying a circuit configuration by reducing the number of terminals.
[0020]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 is a power supply side terminal connected to a power supply, a load side terminal connected to an electric load, and connected to the power supply side terminal, and is capable of controlling power. Power control means, sensor power supplied with power controlled by the power control means, and a sensor means for detecting a detection target in a non-contact manner, connected to the power supply side terminal and the load side terminal, the sensor means A switch device which is turned on when detected and conducts between the power supply side terminal and the load side terminal, wherein the power control unit and the minus side terminal of the sensor unit are connected to the load side terminal. It is assumed that they are connected.
[0021]
According to a second aspect of the present invention, in the sensor device according to the first aspect, the power control unit is a converter capable of increasing a voltage applied to the sensor unit.
[0022]
According to a third aspect of the present invention, in the sensor device according to the first or second aspect, the switch means includes: a source connected to the power supply side terminal; a gate connected to the sensor means; The gist is an FET comprising a drain connected to a load side terminal.
[0023]
According to a fourth aspect of the present invention, in the sensor device according to any one of the first to third aspects, the sensor device is connected between the sensor unit and the switch unit, and detects a detection signal output from the sensor unit. The gist of the present invention is to include a switch control unit that controls on / off of the switch unit based on the size.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
(1st Embodiment)
An embodiment in which the present invention is embodied in a sensor device provided in an automobile and provided with a magnetic sensor for detecting the position of a brake pedal will be described with reference to FIG. Note that the same components as those of the conventional sensor device 51 are denoted by the same reference numerals, and description will be made focusing on portions different from the sensor device 51. The sensor device 11 of the present embodiment is different from the conventional sensor device 51 in the electrical connection of a magnetic sensor 55 as a sensor device and a switch control circuit 58 as a switch control device to a power supply IC 56 as a power control device. Further, the present embodiment differs from the conventional sensor device 51 in that the load side terminal 54 and the ground side terminal 61 are also used as the load side terminal 12. The magnetic sensor 55 can detect the magnetism of a magnetic material such as magnetized iron as a detection target.
[0025]
That is, the sensor device 11 includes the power supply terminal 52 and the load terminal 12. The power supply terminal 52 is connected to a power supply (not shown) including a battery. The load-side terminal 12 has a brake lamp device 53 arranged in series and is grounded.
[0026]
The power supply IC 56 has a positive terminal connected to the power terminal 52 and a negative terminal connected to the load terminal 12. Further, the power supply IC 56 of the present embodiment has a control terminal, and is connected to the magnetic sensor 55 and the switch control circuit 58 so as to be able to control the power by the control terminal. The power supply IC 56 is provided in parallel with a switch circuit 57 as a switch means, and is capable of detecting the voltage of the switch circuit 57. That is, the power supply IC 56 according to the present embodiment has a boosting function, corresponds to an input voltage of, for example, 1.6 V to 18 V, and corrects the voltage applied to the magnetic sensor 55 and the switch control circuit 58 to be always constant. It consists of a possible known DC / DC converter. The battery voltage (power supply voltage) is 8 to 16 V, which is within the range of the power supply IC 56. When a voltage drop occurs between the power supply side terminal 52 and the load side terminal 12 due to the turning on of the switch circuit 57, the power supply IC 56 corrects the voltage drop and boosts the voltage, and sends the voltage to the magnetic sensor 55 and the switch control circuit 58. It is configured to apply a constant voltage.
[0027]
The switch circuit 57 of the present embodiment includes a series circuit of an FET 57a and a resistor 57b. Note that when the FET 57a is conductive, the switch circuit 57 is called "on", and when the FET 57a is nonconductive, the switch circuit 57 is called "off".
[0028]
Further, the magnetic sensor 55 of the sensor device 11, the power supply IC 56, the switch circuit 57, and the negative terminal of the switch control circuit 58 are all connected to the load terminal 12 as the ground side. That is, the sensor device 11 is configured to include the two terminals of the power supply side terminal 52 and the load side terminal 12 by using the load side terminal 54 and the ground side terminal 61 as the load side terminal 12 in the related art. I have.
[0029]
As a result, the brake lamp device 53 of the present embodiment is always energized through the magnetic sensor 55 and the like even when the switch circuit 57 is in the off state. However, when the switch circuit 57 is turned off, the LED 53a of the brake lamp device 53 cannot be sufficiently turned on, and a dark current (approximately 1 mA) flows in the same state as the non-lighting state (hereinafter, referred to as a non-lighting state). I have. On the other hand, when the switch circuit 57 is turned on, a current (approximately 200 mA) flows through the switch circuit 57 to the brake lamp device 53 so that the LED 53a is sufficiently turned on.
[0030]
Next, the operation of the sensor device 11 will be described.
By the way, in the rest state, the switch control circuit 58 turns off the switch circuit 57 because the detection signal input by the magnetic sensor 55 is at the L level. In the rest state, the power supplied from the power supply is controlled by the power supply IC 56, and a constant power is supplied to the magnetic sensor 55 and the switch control circuit 58. For this reason, the magnetic sensor 55 is always supplied with a constant power in the rest state, and can detect magnetism. The electric power supplied to the magnetic sensor 55 and the switch control circuit 58 is always supplied to the brake lamp device 53 via the load terminal 12. At this time, since only a weak dark current flows through the LED 53a, the LED 53a is in a non-lighting state.
[0031]
Next, when the brake pedal is depressed from the rest state, the switch control circuit 58 outputs the control signal to the gate G of the switch circuit 57 because the detection signal input by the magnetic sensor 55 becomes H level. I do. Then, the switch circuit 57 is turned on.
[0032]
As a result, the sensor device 11 supplies a larger current to the brake lamp device 53 via the switch circuit 57 than the dark current in the rest state. As a result, the LED 53a of the brake lamp device 53 lights sufficiently to function as a brake lamp. When the depression of the brake pedal is stopped so as to return to the rest state, and the amount of magnetic flux detected by the magnetic sensor 55 becomes smaller than the threshold value in the comparison circuit of the switch control circuit 58, the switch control circuit 58 switches to the switch circuit 57. No control signal is output to As a result, the switch circuit 57 is turned off and returns to the above-mentioned rest state.
[0033]
Therefore, according to the above embodiment, the following effects can be obtained.
(1) In the above embodiment, the load-side terminal 54 and the ground-side terminal 61 of the conventional sensor device 51 are also used as the load-side terminal 12, and the sensor device 11 is connected to the two terminals of the power-supply-side terminal 52 and the load-side terminal 12. A configuration was provided.
[0034]
Therefore, as compared with the conventional sensor device 51, the number of terminals of the sensor device 11 can be reduced, and the cost can be reduced and the circuit configuration can be simplified.
(2) In the above embodiment, the sensor device 11 includes the power supply IC 56 having a boost function.
[0035]
Therefore, stable power can be supplied to the magnetic sensor 55 and the switch control circuit 58.
The above embodiment may be modified as follows.
[0036]
In the above embodiment, the sensor device 11 is embodied as a sensor device provided in an automobile and detecting whether or not a brake pedal is depressed, but may be embodied as another sensor device.
[0037]
In the above embodiment, the sensor included in the sensor device 11 is the magnetic sensor 55, but any other sensor that requires power supply, such as an optical sensor or a pressure sensor, may be used.
[0038]
In the above embodiment, the switch control circuit 58 including the amplifier circuit and the comparison circuit is provided in the sensor device 11, but may be omitted. In this case, for example, an amplification circuit may be provided in the magnetic sensor 55, and the detection signal amplified by the amplification circuit may be output to the switch circuit 57 without being compared with a threshold value.
[0039]
In the above embodiment, the switch circuit 57 is an FET, but may be, for example, a bipolar transistor or the like.
In the above-described embodiment, the power supply IC 56 is provided with a step-up function so that the voltages of the magnetic sensor 55 and the switch control circuit 58 can be constantly stepped up. The function may be activated. In this way, power consumption by the power supply IC 56 can be reduced. Further, the power supply IC 56 does not need to have the boosting function.
[0040]
Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below together with their effects.
(1) The sensor device according to any one of claims 1 to 4, wherein the sensor unit includes a magnetic sensor that detects magnetism of a magnetic body as the detection target.
[0041]
【The invention's effect】
As described above in detail, according to the present invention, there is an effect that the cost can be reduced and the circuit configuration can be simplified by reducing the number of terminals.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing one embodiment of a sensor device of the present invention.
FIG. 2 is a circuit diagram showing a conventional sensor device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Sensor device, 12 ... Load terminal, 52 ... Power supply terminal, 53 ... Electrical load, 55 ... Magnetic sensor as sensor means, 56 ... Power supply IC as power control means, 57 ... Switch circuit as switch means, 57a: FET, 58: switch control circuit as switch control means, D: drain, G: gate, S: source.

Claims (4)

A power supply side terminal connected to the power supply,
A load terminal connected to an electric load,
Power control means connected to the power supply side terminal and capable of controlling power,
Sensor means for detecting the detection target in a non-contact manner while the power controlled by the power control means is supplied,
A switch connected to the power supply side terminal and the load side terminal, the switch being turned on when the sensor unit detects the current, and conducting between the power supply side terminal and the load side terminal.
A sensor device, wherein the negative terminals of the power control unit and the sensor unit are connected to the load side terminal. The sensor device according to claim 1, wherein the power control unit is a converter capable of increasing a voltage applied to the sensor unit. 2. The device according to claim 1, wherein the switch means is an FET including a source connected to the power supply terminal, a gate connected to the sensor means, and a drain connected to the load terminal. The sensor device according to claim 2. A switch control unit that is connected between the sensor unit and the switch unit and that controls on / off of the switch unit based on a magnitude of a detection signal output from the sensor unit. The sensor device according to claim 1.

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