Signal processing circuit and sensor system

• US 9,915,684 B2
• Filed: 01/22/2015
• Issued: 03/13/2018
• Est. Priority Date: 02/24/2014
• Status: Active Grant

• Current Assignee: Alps Alpine Co., Ltd.
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Iikura, Akihisa, Sawataishi, Tomoyuki
• Primary Examiner(s): Yi, Roy Y
• Assistant Examiner(s): Aiello, Jeffrey
• Application Number:
  US14/603,182
• Publication Number:
  US 20150241197A1
• Time in Patent Office: 1,146 Days
• Field of Search: 702 71, 702 1, 327306, 327 65, 327205, 324 63, 324207
• CPC Class Codes: G01D 2218/10 Testing of sensors or measuring arrangements
• CPC Class Codes: G01D 5/24466 Comparison of the error value to a threshold
• CPC Class Codes: G01D 5/24476 Signal processing G01D5/2448 - G01D5/24495 take precedence
• CPC Class Codes: G01R 13/0218 Circuits therefor

Abstract

A sensor detects the rotation of a component (object) of a vehicle in a non-contact manner, and generates a differential signal according to the rotation. Two comparators have different hysteresis characteristics. At both edges of one signal that is an output of one of the comparators, if a signal of the other comparator is not at the same level, it is determined that a distance (gap) between an object and the sensor is within a predetermined range in which the differential signal is effective.

Claims

1. A signal processing circuit, comprising:

a first comparator having a first hysteresis characteristic having a first hysteresis width, the first comparator comparing a first input signal and a second input signal and outputting a first output signal according to a comparison result and the first hysteresis characteristic, the first and second input signals form a differential pair providing a differential signal;

a second comparator having a second hysteresis characteristic having a second hysteresis width, the second hysteresis characteristic being different from the first hysteresis characteristic, the second comparator comparing the first input signal and the second input signal and outputting a second output signal according to a comparison result and the second hysteresis characteristic; and

a signal generating circuit configured to generate a determination signal based on the first and second output signals, the determination signal indicating whether or not an amplitude of the differential signal satisfies predetermined conditions,

wherein the first hysteresis is being narrower than the second hysteresis width and the signal generating circuit generates the determination signal based on levels of the second output signal at rising and falling edges of the first output signal.

8. A sensor system, comprising:

the signal processing circuit of claim 1; and

a sensor configured to detect a rotation of an object in a non-contact manner and generate the first input signal and the second input signal which form the differential pair providing the differential signal according to a detection result.

2. A signal processing circuit, comprising:

a first comparator having a first hysteresis characteristic, the first comparator comparing a first input signal and a second input signal and outputting a first output signal according to a comparison result and the first hysteresis characteristic, the first and second input signals form a differential pair providing a differential signal;

a second comparator having a second hysteresis characteristic different from the first hysteresis characteristic, the second comparator comparing the first input signal and the second input signal and outputting a second output signal according to a comparison result and the second hysteresis characteristic; and

a signal generating circuit configured to generate a determination signal based on the first and second output signals, the determination signal indicating whether or not an amplitude of the differential signal satisfies predetermined conditions,

wherein

the first comparator inverts a logic level of the first output signal when a level of the first input signal becomes higher than a level of the second input signal by an amount greater than a first threshold value, and inverts the logic level of the first output signal when the level of the second input signal becomes higher than the level of the first input signal by an amount greater than a second threshold value, and

the second comparator inverts a logic level of the second output signal when the level of the first input signal becomes higher than the level of the second input signal by an amount greater than a third threshold value higher than the first threshold value, and inverts the logic level of the second output signal when the level of the second input signal becomes higher than the level of the first input signal by an amount greater than a fourth threshold value higher than the second threshold value.

3. A sensor system, comprising:

the signal processing circuit of claim 2; and

a sensor configured to detect a rotation of an object in a non-contact manner and generate the first input signal and the second input signal which form the differential pair providing the differential signal according to a detection result.

4. A signal processing circuit, comprising:

a first comparator having a first hysteresis characteristic, the first comparator comparing a first input signal and a second input signal and outputting a first output signal according to a comparison result and the first hysteresis characteristic, the first and second input signals form a differential pair providing a differential signal;

a second comparator having a second hysteresis characteristic different from the first hysteresis characteristic, the second comparator comparing the first input signal and the second input signal and outputting a second output signal according to a comparison result and the second hysteresis characteristic; and

a signal generating circuit configured to generate a determination signal based on the first and second output signals, the determination signal indicating whether or not an amplitude of the differential signal satisfies predetermined conditions,

wherein the signal generating circuit generates the determination signal having a predetermined logic level when a logic level of the second output signal at a rising edge of the first output signal is different from a logic level of the second output signal at a falling edge of the first output signal.

5. A sensor system, comprising:

the signal processing circuit of claim 4; and

a sensor configured to detect a rotation of an object in a non-contact manner and generate the first input signal and the second input signal which form the differential pair providing the differential signal according to a detection result.

6. A signal processing circuit, comprising:

a first comparator having a first hysteresis characteristic, the first comparator comparing a first input signal and a second input signal and outputting a first output signal according to a comparison result and the first hysteresis characteristic, the first and second input signals form a differential pair providing a differential signal;

a second comparator having a second hysteresis characteristic different from the first hysteresis characteristic, the second comparator comparing the first input signal and the second input signal and outputting a second output signal according to a comparison result and the second hysteresis characteristic; and

a signal generating circuit configured to generate a determination signal based on the first and second output signals, the determination signal indicating whether or not an amplitude of the differential signal satisfies predetermined conditions,

wherein the signal generating circuit includes;

a first flip-flop circuit having a first clock pulse terminal that receives an inverted signal of the first output signal, a first data input terminal that receives an inverted signal of the second output signal, and a first output terminal;

a second flip-flop circuit having a second clock pulse terminal that receives the first output signal, a second data input terminal that receives the inverted signal of the second output signal, and a second output terminal; and

a logic circuit that outputs, as the determination signal, an exclusive OR of an output signal from the first output terminal and an output signal from the second output terminal.

7. A sensor system, comprising:

the signal processing circuit of claim 6; and

a sensor configured to detect a rotation of an object in a non-contact manner and generate the first input signal and the second input signal which form the differential pair providing the differential signal according to a detection result.