JP2007232579A - Sensor signal input device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To use a sensor signal input device for processing a detection signal from a sensor and inputting it into a control circuit or the like, as it is, without altering the device structure even when the specification of a sensor to be connected to an input terminal is different. <P>SOLUTION: The sensor signal input device comprises: a one-shot generating circuit 30 for applying voltage to a rotation sensor 4 connected to the input terminal until a predetermined determination time passes after powering on and making current flow in the rotation sensor 4; and a sensor determination circuit 40 for determining whether the rotation sensor 4 is an MPU sensor formed of a pick-up coil or an MRE sensor formed of a magnetoresistive element by taking input terminal voltage while current carrying to the rotation sensor 4 by the one shot generating circuit 30, and comparing the terminal voltage with determination voltages Vr4 and Vr5 for sensor type determination with comparators 42 and 44. According to the determination result, the circuit used for wave-shaping the detection signal is automatically changed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sensor signal input device that processes a detection signal from a sensor and inputs the detected signal to a control circuit or the like.

  2. Description of the Related Art Conventionally, for example, in an engine control device mounted on an automobile, a rotation sensor that generates a pulse signal for each predetermined crank angle in synchronization with the rotation of a crankshaft in order to detect the rotation speed or rotation angle of the engine in use.

  In addition, there are various sensors with different detection methods, such as MPU sensors that detect the rotation of the crankshaft using a pickup coil and MRE sensors that detect using a magnetoresistive element. Can be used with any rotation sensor (see, for example, Patent Document 1).

  For this reason, when designing an engine control device, a rotation sensor suitable for control is selected based on the specifications of the engine to be controlled, and a sensor signal input circuit is selected according to the type of the selected rotation sensor. Was configured.

  For example, FIG. 4A shows a configuration of a sensor signal input device assembled on a circuit board of an engine control device when an MPU sensor is used as a rotation sensor, and FIG. 4B shows an MRE sensor as a rotation sensor. The structure of the sensor signal input device assembled | attached on the same circuit board when using is shown.

As is apparent from these drawings, the MPU sensor input device includes a noise removal filter including resistors Ra and Rb and capacitors Ca and Cb, and a waveform for a detection signal that has passed through the filter. An input IC (1) for an MPU sensor that performs processing such as shaping is provided, whereas an input device for an MRE sensor includes a pull-up resistor Ro for supplying operating power to the MRE sensor, a resistor Rc, A noise removing low-pass filter including capacitors Cc and Cd and an input IC (2) for processing a detection signal from the MRE sensor (such as waveform shaping) are provided.
JP 2003-214905 A

  As described above, in the conventional engine control device, it is necessary to change the detection signal input circuit and the input IC according to the type of the rotation sensor to be used, and these parts are shared between engine control devices of different specifications. This has hindered mass production of engine control devices.

  Also, it is conceivable to share the input IC by designing the input IC so that the operation of the input IC can be adjusted by an external component such as a resistor. In this case, the input IC can be shared. Since the external parts of the input IC must be changed according to the type of rotation sensor to be used, the parts and the manufacturing process cannot be made common among the engine control devices.

  This problem is not limited to the sensor signal input device that takes in the detection signal from the rotation sensor, and similarly occurs if the sensor signal input device is used in a device that can use sensors with different specifications.

  The present invention has been made in view of such problems, and in a sensor signal input device that processes a detection signal from a sensor and inputs it to a control circuit or the like, even if the specifications of the sensor connected to the input terminal are different. An object of the present invention is to enable use as it is without changing the device configuration.

  In the sensor signal input device according to claim 1, which is made to achieve such an object, the energization means applies a voltage to the input terminal and is connected to the input terminal until a determination time elapses after activation. Apply current to the sensor. Then, the determining means determines the type of the sensor connected to the input terminal based on the terminal voltage of the input terminal, and the selecting means selects the detection signal from the plurality of signal processing means based on the determination result. The signal processing means used for processing is selected.

  That is, in the present invention, after starting the device, during the determination time, a voltage is applied to the input terminal and a current is passed through the sensor to detect a terminal voltage that changes due to the internal resistance of the sensor, and the detected terminal voltage. The type of the sensor is specified from the above, and the signal processing means suitable for the sensor is selected from the plurality of signal processing means.

  Therefore, according to the sensor signal input device of the present invention, it is not necessary to change the parts used such as the input IC according to the type of sensor connected to the input terminal as in the prior art, and a plurality of types of sensors having different specifications. Can be used as they are.

  Therefore, according to the present invention, it is possible to share the sensor signal input device among the control devices that use sensors having different specifications, such as the MPU sensor and the MRE sensor described above, and to reduce the manufacturing cost of the control device. Become.

  Here, since the determination means is for specifying the type of the sensor connected to the input terminal from the voltage value of the terminal voltage, a determination voltage for sensor identification is set in advance, and this determination voltage and the terminal It may be configured to identify the type of sensor by comparing the voltage.

  For example, like the MPU sensor and MRE sensor described above, one sensor is specified from two types of sensors, and the signal processing means used for processing the detection signal is selected from the two signal processing means. In such a case, the determination means may be configured as described in claim 2.

  That is, in the sensor signal input device according to claim 2, the determination means includes two comparators that respectively compare the terminal voltage with two types of determination voltages (first determination voltage and second determination voltage). A first comparator and a second comparator) and a gate circuit. The first comparator outputs a first identification signal indicating that the first sensor is connected to the input terminal when the terminal voltage exceeds the first determination voltage, and the gate circuit If the second comparator determines that the terminal voltage has exceeded the second determination voltage when the first identification signal is not output from the comparator, it indicates that the second sensor is connected to the input terminal. A second identification signal is output.

  Therefore, either the first identification signal or the second identification signal is output from the determination means according to the type of the sensor connected to the input terminal, and the selection means outputs from the determination means. These two types of identification signals can be used as they are as drive signals for two types of signal processing means corresponding to each sensor.

  By the way, when the determination means is configured as described in claim 2, depending on the sensor, it takes time until the terminal voltage reaches a voltage value corresponding to the internal resistance of the sensor after the energization means starts energizing the sensor. Even though the sensor connected to the input terminal is the first sensor having a large internal resistance, the second identification signal is temporarily output from the gate circuit, and the signal processing means corresponding to the second sensor is selected. It is thought that it is done.

  Therefore, in order to prevent such a problem, an initialization circuit is provided as described in claim 3, and the second circuit from the gate circuit is operated until the initialization time elapses after the device is started up by the operation of the initialization circuit. The output of the identification signal may be prohibited.

  In other words, in this way, the second identification signal can be prohibited from being output from the gate circuit until the initialization time has elapsed after the device is started up. Even when it takes time for the terminal voltage to exceed the first determination time due to a time constant on the sensor side, it is possible to prevent the second identification signal from being erroneously output from the gate circuit. .

  On the other hand, in the apparatus according to claim 2 or claim 3, after the apparatus is started, after the output from the determination means to the selection means is determined to be the first identification signal or the second identification signal, the output is caused by noise or the like. It is desirable that the signal processing means selected by the selection means is not changed due to fluctuation.

  For this purpose, as described in claim 4, when a determination signal indicating that the terminal voltage exceeds the second determination voltage is output from the second comparator, the first voltage holding means When the input path of the terminal voltage to the second comparator is held at a voltage higher than the second determination voltage and the second identification signal is output from the gate circuit, the second voltage holding means is connected to the terminal to the first comparator. The voltage input path may be held at a voltage lower than the first determination voltage. That is, in this way, when the terminal voltage is a voltage value between the second determination voltage and the first determination voltage, the output of the second identification signal from the gate circuit can be held.

  Further, as described in claim 5, when the first identification signal is output from the first comparator, the third voltage holding means sets the input path of the terminal voltage to the first comparator to the first By holding the voltage higher than the determination voltage, the output of the first identification signal from the first comparator may be held.

  Next, the energization unit only needs to apply a voltage to the input terminal and allow the current to flow through the sensor for the determination time set for determining the sensor type after the apparatus is activated. For this reason, the energization means may be configured to provide a switch connected to the power supply line via a resistor as described in claim 6 and to turn on this switch only during the determination time.

  In this case, if the terminal voltage is input to each comparator of the determination means via the switch of the energization means as described in claim 6, the input path of the terminal voltage to the determination means can be simplified. Can be configured.

  Further, when the input path of the terminal voltage from the energizing means to the determining means and the energizing means are configured as described above, the third voltage holding means for holding the output of the first identification signal from the first comparator is claimed as As described in item 6, when the second identification signal is output from the gate circuit after the determination time has elapsed, the switch of the energizing means is held in the on state, and the second identification signal is output from the gate circuit. When there is not, it is good to comprise so that the switch of an electricity supply means may be turned off.

  That is, in this way, when the second identification signal is not output from the gate circuit, in other words, when the first identification signal is output from the first comparator, the first determination is made to each comparator. A power supply voltage higher than the voltage can be applied, and the output of the first identification signal from the first comparator can be held.

  Furthermore, when the third voltage holding means is configured as described above, when the second sensor is connected to the input terminal and the second identification signal is output from the gate circuit, the switch of the energizing means is turned on. When the first sensor is connected to the input terminal and the first identification signal is output from the first comparator, the switch of the energizing means is turned off. The power supply to the first sensor can be cut off.

  For this reason, in the sensor signal input device according to claim 6, the active sensor capable of generating a detection signal without receiving external power supply is further provided in the first sensor as described in claim 7. The second sensor may be a passive sensor that operates by receiving power supply through the input terminal.

As an active sensor, for example, the above-mentioned MPU sensor can be cited, and as a passive sensor, for example, the above-mentioned MRE sensor can be cited.
Next, a sensor signal input device according to an eighth aspect of the present invention is an input device for a rotation sensor that takes in a detection signal from a rotation sensor via an input terminal and shapes the waveform of the detection signal. Therefore, if this device is incorporated in a control device that controls the control object based on the detection signal from the rotation sensor, such as the engine control device described above, the control device can be mass-produced and the cost can be reduced. Become.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram illustrating the overall configuration of the sensor signal input device according to the embodiment.
As shown in FIG. 1, the sensor signal input device of this embodiment is assembled with a control arithmetic CPU or the like on a circuit board of an electronic control unit (ECU) 2 that controls an automobile engine, and detects the rotation of the engine. A detection signal from the rotation sensor 4 is acquired via input terminals Ti1 and Ti2 connected to the positive and negative output terminals of the rotation sensor 4, and the acquired detection signal is shaped into a rectangular waveform and input to the CPU. Is.

  Of the two input terminals Ti1 and Ti2, the input terminal Ti2 connected to the negative electrode side of the rotation sensor 4 is connected to the ground terminal Tg connected to the chassis of the vehicle and held at the ground (GND) potential of the ECU 2. Has been.

  The sensor signal input device of the present embodiment is similar to the conventional device shown in FIG. 4 in that an input circuit (in other words, a filter for removing noise) 6 including resistors R1 and R2 and capacitors C1 and C2, The input IC 10 is configured to perform processing such as waveform shaping on the detection signal that has passed through the input circuit 6.

  Further, the input IC 10 has a rectangular wave signal (that is, a pulse signal) that changes in synchronism with the rotation of the engine with respect to the CPU regardless of which MPU sensor or MRE sensor is connected to the input terminals Ti1 and Ti2. It is configured to be able to input.

  That is, the input IC 10 is provided with a waveform shaping circuit 20 for shaping the detection signal input via the input circuit 6, but the detection signal from the MPU sensor and the detection signal from the MRE sensor are the same. Since the signal levels are different, the waveform shaping circuit 20 compares the detection signal with the reference voltage Vr1 in order to shape the detection signal from the MPU sensor, and when the detection signal is greater than the reference voltage Vr1. When the detection signal is greater than the reference voltage Vr2 by comparing the detection signal with the reference voltage Vr2 in order to shape the waveform of the detection signal from the MRE sensor and the comparator 22 that generates a high-level pulse signal. And a comparator 24 for generating a pulse signal that goes to a high level.

  In addition, the waveform shaping circuit 20 is provided with bidirectional switches 26 and 28 for conducting and blocking the detection signal input paths to the comparators 22 and 24 for the MPU sensor and the MRE sensor. The outputs of the comparators 22 and 24 are connected to the CPU via an OR gate.

  For this reason, in the waveform shaping circuit 20 of the present embodiment, either one of the two comparators 22 and 24 can be operated by selectively turning on one of the bidirectional switches 26 and 28. The detection signal after waveform shaping (that is, a pulse signal) output from the operated comparator 22 or 24 can be input to the CPU.

  Next, the input IC 10 includes an ECU 2 (in other words, in order to selectively turn on either of the bidirectional switches 26 and 28 according to the type of the rotation sensor 4 connected to the input terminals Ti1 and Ti2. A one-shot generation circuit 30 that applies a voltage to the input terminal Ti1 and passes a current to the rotation sensor 4 until a predetermined determination time elapses after the power supply to the input IC 10) is turned on, and the one-shot generation Whether or not the rotation sensor 4 connected to the input terminals Ti1 and Ti2 is an MPU sensor based on the change in the acquired terminal voltage when the circuit 30 is passing current through the rotation sensor 4 It is determined whether the sensor is an MRE sensor, and a drive signal (high level) Vo1 or Vo2 for turning on the bidirectional switch 26 or 28 is output according to the determination result. After turning on the power to the sensor determination circuit 40 and the ECU 2, the output terminal is grounded for the initialization time shorter than the determination time, and the output terminal is opened when the initialization time has elapsed. And an initialization circuit 50.

Hereinafter, configurations and operations of the one-shot generation circuit 30, the sensor determination circuit 40, and the initialization circuit 50 will be described.
In the following description, FIG. 2 is an electric circuit diagram showing the configuration of each of these circuits. FIG. 3 shows a case where the rotation sensor 4 is an MPU sensor (a) and the rotation sensor 4 is an MRE sensor. It is a time chart showing the voltage change of each part of case (b).

  As shown in FIG. 2, the one-shot generation circuit 30 includes a capacitor C3 that is charged via a resistor R3 from a power supply line (power supply voltage VB) after power is supplied to the ECU 2, and a charging voltage and a reference voltage for the capacitor C3. Comparing Vr3, the comparator 32 that outputs a high level signal during the determination time until the charging voltage to the capacitor C3 reaches the reference voltage Vr3 after the power supply to the ECU 2 is turned on, Compared with the pull-up resistor R4 for connecting the output and the power supply line, the resistor R5 having one end connected to the power supply line, and the bidirectional switch 36 for connecting the input terminal Ti1 to the other end of the resistor R5 An OR gate 34 that outputs a drive signal (high level) to the bidirectional switch 36 to turn on the bidirectional switch 36 when the output of the detector 32 is at a high level; It is constructed from.

  Next, the sensor discrimination circuit 40 takes in the terminal voltage of the input terminal Ti1 via the bidirectional switch 36 and the resistors R6 and R7, and compares the fetched terminal voltage with the judgment voltages Vr4 and Vr5 for sensor discrimination, respectively. The comparators 42 and 44 that output a high level signal when the terminal voltage is higher than the determination voltage Vr4 or Vr5, and the pull-up resistor R8 that connects the output of the comparators 42 and 44 and the power supply line, R9, an AND gate 46 to which the output from the comparator 42 is inverted and input, and the output from the comparator 44 is input as it is, the anode is connected to the output of the comparator 44, and the cathode is the resistor R7 and the comparator The base is connected to the output of the AND gate 46 via the resistor R10, the collector is the resistor R6, and the comparator. Is connected to the junction of the 2, the emitter is composed of NPN transistors Tr1 Prefecture, which is grounded.

  The initialization circuit 50 compares the capacitor C4 charged from the power supply line via the resistor R11 after the power supply to the ECU 2 is turned on, and the power supply voltage to the ECU 2 by comparing the charging voltage to the capacitor C4 with the reference voltage Vr6. The comparator 52 that outputs a high level signal during the initialization time until the charging voltage to the capacitor C4 reaches the reference voltage Vr6 after being turned on, and the resistor R12 that connects the output of the comparator 52 and the power supply line A resistor R13 having one end connected to the output of the comparator 52, a base connected to the other end of the resistor R13, and a collector serving as an output terminal of the initialization circuit 50. 34 and an NPN transistor Tr2 connected to the output of the AND gate 46 in the sensor discriminating circuit 40 and having the emitter grounded. It is al configuration.

  In the input IC 10 configured in this way, regardless of the type of the rotation sensor 4 connected to the input terminals Ti1 and Ti2, after the power is supplied to the ECU 2, until the determination time elapses, The output becomes a high level (see FIG. 3), the bidirectional switch 36 is turned on by this signal, and the rotation sensor 4 receives a current from the power supply line of the power supply voltage VB through the resistor R5 and the bidirectional switch 36. Will flow.

  The current flowing into the rotation sensor 4 at this time varies depending on the type of rotation sensor 4 (in other words, its internal resistance), and the internal resistance during the non-detection operation of the MPU sensor and the MRE sensor is generally about “6: 1”. Therefore, when the rotation sensor 4 is an MPU sensor and when the rotation sensor 4 is an MRE sensor, the terminal voltage of the input terminal Ti1 also has different voltage values in proportion to this ratio.

  Therefore, the determination voltages Vr4 and Vr5 of the comparators 42 and 44 of the sensor determination circuit 40 are “Vr4> Vmre> Vr5” with respect to the terminal voltage Vmre when the rotation sensor 4 is an MRE sensor, and the rotation sensor 4 The voltage value is set so that “Vmpu> Vr4> Vr5” with respect to the terminal voltage Vmpu in the case of the MPU sensor.

  For this reason, when the rotation sensor 4 is an MPU sensor, the outputs from the comparators 42 and 44 are both at a high level and the output of the AND gate 46 is at a low level, as shown in FIG. The high level signal output from the comparator 42 is output to the waveform shaping circuit 20 as a drive signal Vo1 for selectively turning on the bidirectional switch 26.

  Therefore, after that, in the waveform shaping circuit 20, the detection signal from the rotation sensor (MPU sensor in this case) 4 input via the input circuit 6 is waveform-shaped by the comparator 22, and is sent to the CPU via the OR gate 29. Will be output.

  On the other hand, when the rotation sensor 4 is an MRE sensor, the terminal voltage input to the comparators 42 and 44 is between the determination voltages Vr4 and Vr5 immediately after turning on the power to the ECU 2, as shown in FIG. Thus, the output of the comparator 42 becomes low level and the output of the comparator 44 becomes high level.

  Since the output of the comparator 44 is connected to the input path of the terminal voltage of the comparator 44 via the diode D1, when the output of the comparator 44 becomes high level, the input path of the terminal voltage of the comparator 44 is also changed. After that, the output of the comparator 44 is kept at a high level until the power supply to the ECU 2 is cut off (in other words, until the power supply voltage VB becomes zero).

  As described above, when the input path of the terminal voltage of the comparator 44 becomes a high level (substantially the power supply voltage VB), the input voltage to the comparator 42 also changes. Since the voltage is applied to the rotation sensor 4 (in this case, the MRE sensor), the input voltage to the comparator 42 does not exceed the determination voltage Vr4.

  When the output of the comparator 42 is low level and the output of the comparator 44 is high level after the power supply to the ECU 2 is turned on, a high level signal is output from the AND gate 46. Is output to the ground through the NPN transistor Tr2 of the initialization circuit 50 until the initialization time elapses after the power is turned on, so that the output from the AND gate 46 is suppressed to a low level.

  Next, when the initialization time elapses after the power is turned on, the NPN transistor Tr2 of the initialization circuit 50 is turned off and the output of the initialization circuit 50 is opened (opened). Become high level. The high level signal output from the AND gate 46 in this way is output to the waveform shaping circuit 20 as the drive signal Vo2 for selectively turning on the bidirectional switch 28.

  Therefore, after that, in the waveform shaping circuit 20, the detection signal from the rotation sensor (in this case, the MRE sensor) 4 input via the input circuit 6 is waveform-shaped by the comparator 24, and the CPU is passed through the OR gate 29. Will be output.

  That is, according to the sensor signal input device of the present embodiment, the rotation sensor 4 connected to the input terminals Ti1 and Ti2 is identified as an MPU sensor or an MRE sensor, and the identified rotation sensor 4 As a signal processing circuit for processing the detection signal, one of the two comparators 22 and 24 provided in the waveform shaping circuit 20 is automatically selected.

  Therefore, according to the present embodiment, there is no need to change the input IC or the like according to the type of the rotation sensor 4 connected to the input terminals Ti1 and Ti2 as in the prior art, and the ECU 2 and the MRE sensor using the MPU sensor The sensor signal input device can be shared with the ECU 2 to be used, and the manufacturing cost of the ECU 2 can be reduced.

  Next, in the present embodiment, when the output of the AND gate 46 becomes high level as described above, the NPN transistor Tr1 is turned on, and the input path of the terminal voltage to the comparator 42 is grounded. The input of the comparator 42 is held at the ground potential (0 V), and its output is fixed at a low level.

  Therefore, according to the present embodiment, after the output from the AND gate 46 is once determined, the output from the comparator 42 is inverted due to noise or the like, and the output from the AND gate 46 is also inverted. The output of the drive signal Vo2 from the AND gate 46 can be held.

  Furthermore, since the output of the AND gate 46 is connected to the input of the OR gate 34 of the one-shot generation circuit 30, the output of the AND gate 46 becomes high level (that is, the rotation sensor 4 is connected to the MRE sensor). In the case where the output from the comparator 32 becomes low level after the determination time has elapsed after the power is turned on, the output from the OR gate 34 is held at high level, and the bidirectional switch 36 Holds on.

  For this reason, when the rotation sensor 4 is an MPU sensor that does not require power supply, the bidirectional switch 36 is turned on only for the determination time required to determine the type of the rotation sensor 4, and power is supplied to operate the rotation sensor 4. In the case of an MRE sensor that needs to be turned on, the bidirectional switch 36 is continuously turned on after the power is turned on, and the rotation sensor 4 is continuously supplied with power via the resistor R5.

  In this way, when the rotation sensor 4 is an MRE sensor, the resistor R5 in the one-shot generation circuit 30 functions as the pull-up resistor Ro shown in FIG. Then, the input circuit 6 can be configured as a common filter circuit for the MPU sensor and the MRE sensor by appropriately adjusting the values of the resistors R1 and R2 and the capacitors C1 and C2 constituting the input circuit 6.

  When the rotation sensor 4 is an MPU sensor, the bidirectional switch 36 is turned off when the determination time after power-on has elapsed. In this state, the terminal voltage input path of the comparators 42 and 44 is connected via the resistor R5. Since the power supply voltage VB is applied, the outputs from the comparators 42 and 44 are surely held at a high level, and the output from the comparator 42 is prevented from being inverted due to noise or the like. can do.

  In the present embodiment, the comparators 22 and 24 in the waveform shaping circuit 20 correspond to a plurality of signal processing means of the present invention, and the one-shot generation circuit 30 corresponds to an energization means of the present invention, and sensor discrimination. The circuit 40 corresponds to the determination unit of the present invention, and the bidirectional switches 26 and 28 in the waveform shaping circuit 20 correspond to the selection unit of the present invention.

  The comparator 42 in the sensor discrimination circuit 40 corresponds to the first comparator of the present invention, and the determination voltage Vr4 corresponds to the first determination voltage of the present invention, and is output from the comparator 42 to the waveform shaping circuit 20. The driven signal Vo1 corresponds to the first identification signal of the present invention. The comparator 44 in the sensor discrimination circuit 40 corresponds to the second comparator of the present invention, the determination voltage Vr5 corresponds to the second determination voltage of the present invention, and the AND gate 46 corresponds to the gate circuit of the present invention. The drive signal Vo2 output from the AND gate 46 to the waveform shaping circuit 20 corresponds to the second identification signal of the present invention.

  Furthermore, the diode D1 in the sensor determination circuit 40 corresponds to the first voltage holding means of the present invention, the resistor R10 and the NPN transistor Tr1 correspond to the second voltage holding means of the present invention, and the one-shot generation circuit 30. The OR gate 34 corresponds to the third voltage holding means of the present invention.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various aspect can be taken in the range which does not deviate from the summary of this invention.
For example, in the above-described embodiment, the sensor signal input device used to capture the detection signal from the rotation sensor in the electronic control device that controls the vehicle engine has been described. However, the present invention is not limited to the engine such as wheel rotation. Even a device that inputs a detection signal from a rotation sensor that detects the rotation of the rotation sensor or a device that inputs a detection signal from a sensor other than the rotation sensor can be applied in the same manner as in the above embodiment. it can.

  In the above embodiment, the type of sensor connected to the input terminal is identified from the two types of rotation sensors, and the signal processing circuit (comparators 22 and 24) used to process the detection signal is selected. However, the sensor signal input device of the present invention has three or more sensor identification comparators and three or more signal processing circuits provided in the sensor discrimination circuit. The type of the sensor connected to the input terminal can be identified and a signal processing circuit used for processing the detection signal can be selected.

It is a block diagram showing the structure of the whole sensor signal input device of embodiment. FIG. 3 is an electric circuit diagram illustrating configurations of a one-shot generation circuit, a sensor determination circuit, and an initialization circuit. 3 is a time chart for explaining the operation of each circuit shown in FIG. 2. It is explanatory drawing explaining the structure of the conventional sensor signal input device.

Explanation of symbols

  2 ... ECU, 4 ... rotation sensor, Ti1, Ti2 ... input terminal, 6 ... input circuit, 10 ... input IC, 20 ... waveform shaping circuit, 22, 24 ... comparators 26, 28 ... bidirectional switch, 29 ... OR gate , 30 ... One shot generation circuit, 32 ... Comparator, 34 ... OR gate, 36 ... Bidirectional switch, 40 ... Sensor discrimination circuit, 42, 44 ... Comparator, 46 ... AND gate, D1 ... Diode, Tr1 ... NPN transistor , 50 ... initialization circuit, 52 ... comparator, Tr2 ... NPN transistor.

Claims (8)

A sensor signal input device that includes an input terminal for capturing a detection signal from a sensor and processes the detection signal input from the input terminal,
A plurality of signal processing means for processing detection signals from sensors having different specifications;
Energization means for applying a voltage to the input terminal and causing a current to flow through the sensor until a predetermined determination time has elapsed after the device is activated;
Determination means for determining the type of sensor connected to the input terminal based on the terminal voltage of the input terminal after the energization means has started energization of the sensor;
A selection means for selecting a signal processing means to be used for processing of a detection signal from the plurality of signal processing means according to a determination result by the determination means;
A sensor signal input device comprising: The determination means includes
It is determined whether or not the terminal voltage exceeds a first determination voltage, and when the terminal voltage exceeds the first determination voltage, a first identification indicating that a first sensor is connected to the input terminal A first comparator for outputting a signal;
A second comparator for determining whether or not the terminal voltage has exceeded a second determination voltage lower than the first determination voltage;
When the second comparator determines that the terminal voltage has exceeded the second determination voltage and the first identification signal is not output from the first comparator, a second sensor is connected to the input terminal. A gate circuit for outputting a second identification signal indicating that
The sensor signal input device according to claim 1, further comprising:   3. The initialization circuit according to claim 2, further comprising an initialization circuit that prohibits the output of the second identification signal from the gate circuit until an initialization time shorter than the determination time elapses after the device is activated. Sensor signal input device. When a determination signal indicating that the terminal voltage exceeds the second determination voltage is output from the second comparator, a voltage higher than the second determination voltage is input to the terminal voltage input path to the second comparator. First voltage holding means for holding
Second voltage holding means for holding a terminal voltage input path to the first comparator at a voltage lower than the first determination voltage when a second identification signal is output from the gate circuit;
The sensor signal input device according to claim 2, further comprising:   When the first identification signal is output from the first comparator, a third voltage holding unit that holds the input path of the terminal voltage to the first comparator at a voltage higher than the first determination voltage is provided. The sensor signal input device according to claim 2, wherein the sensor signal input device is a sensor signal input device. The energization means is configured to flow a current to the sensor by turning on a switch connected to a power supply line via a resistor for the determination time,
Terminal voltage input paths to the first comparator and the second comparator are each connected to the input terminal via a switch of the energizing means,
The third voltage holding unit holds the switch of the energization unit in an ON state when the second identification signal is output from the gate circuit after the determination time has elapsed, and the second identification signal is output from the gate circuit. 6. The switch of the energizing means is turned off when the signal is not output, and the terminal voltage input path to the first comparator is held at a voltage higher than the first determination voltage. The sensor signal input device according to 1.   The first sensor is an active sensor that can generate a detection signal without receiving power supply from the outside, and the second sensor is a passive sensor that operates by receiving power supply through the input terminal. The sensor signal input device according to claim 6, wherein the sensor signal input device is provided.   The sensor signal input device takes in a detection signal from a rotation sensor that generates a detection signal that changes in a cycle synchronized with the rotation of the detection object via the input terminal, and shapes the detection signal by the signal processing means. The sensor signal input device according to claim 1, wherein the sensor signal input device is a rotation sensor input device.

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