Capacitance detection device

A technology for electrostatic capacitance and detection devices, which is applied in the direction of measuring devices, capacitance measurement, radio wave measurement systems, etc., can solve the problems of decreased detection accuracy and increased detection time of electrostatic capacitance, and achieve the effect of shortening time and reducing detection accuracy

Pending Publication Date: 2020-09-22
AISIN CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

As a result, the time required for capacitance detection increases
[0006] On the other hand, when the time required for capacitance detection increases, the influence of low-frequency noise superimposed on the power supply (first and second potential sources) for capacitance detection and the increase

Method used

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Experimental program
Comparison scheme
Effect test

no. 1 approach ＞

[0040] Hereinafter, a first embodiment of the capacitance detection device will be described.

[0041] Such as figure 1 As shown, the electrostatic capacitance detection device includes: a capacitor array 11, a detection capacitor 12 as a detection object of capacitance, a first switch 13, a second switch 14, a third switch 15, a differential amplifier circuit 16 as an amplifier, and an AD conversion circuit. part of the AD conversion circuit 17, and the control circuit 18.

[0042] The capacitor array 11 has a variable combined capacity Cs. That is, if figure 2 As shown, the capacitor array 11 is configured by connecting a plurality of (for example, eight) capacity units 21 in parallel, and the capacity units 21 have capacitors 22 and switches 23 connected in series. The capacities of these plurality of capacitors 22 are set to be different from each other. Specifically, when the capacity of the capacitor 22 with the smallest capacity is represented by C0, the capacities...

no. 2 approach ＞

[0106] Hereinafter, the second embodiment will be described focusing on differences from the first embodiment with reference to the drawings.

[0107] Figure 5 The electrostatic capacity detection device 30 of this embodiment is shown. In addition, in Figure 5 In, for convenience, for figure 1 The corresponding parts of the shown parts are marked with the same symbols.

[0108] The electrostatic capacitance detection device 30 of the present embodiment is a proximity detection sensor mounted on a vehicle to detect that a person has approached a predetermined part of the vehicle. Specifically, for example, it is a sensor that detects that a person's foot touches the rear of the vehicle, or that a person's hand traces near the sliding door of the vehicle. When the proximity detection sensor detects that a predetermined part of a person, which is a target object, approaches, the opening and closing section of the vehicle is automatically opened by an electronic control unit...

no. 3 approach ＞

[0134] Hereinafter, the third embodiment will be described focusing on differences from the first embodiment with reference to the drawings.

[0135] Figure 9 The sequence of processing executed by the control circuit 18 is shown. Figure 9 The shown processing is repeatedly executed by the control circuit 18 at a predetermined cycle. In addition, in Figure 9 In, for convenience, for Figure 6 The processes corresponding to the shown processes are denoted by the same step numbers.

[0136] exist Figure 9 In the series of processes shown, when the process of S28 ends, the control circuit 18 substitutes the differential voltage ΔV obtained in the process of S26 into the differential voltage ΔVa ( S50 ). Then, the control circuit 18 waits until the predetermined time T1 elapses (S52: NO). Here, the specified time T1 is set as a ratio Figure 9 The cycle of processing repeats at short intervals. Then, when the predetermined time T1 elapses (S52: Yes), the control circui...

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PUM

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Abstract

The invention provides a capacitance detection device (30) capable of shortening the time required for detection without reducing the detection accuracy. The device is provided with: a capacitor arrayhaving a plurality of capacitors connected in parallel and having mutually different capacities, the combined capacity of the capacitor array changing; a detection capacitor connected in series to the capacitor array; a switch control unit; a detection unit that detects an intermediate potential, which is a potential of a capacity divided voltage of the power supply obtained from the combined capacity and the capacity of the detection capacitor; an acquisition unit that acquires, as a first synthesized capacity and a second synthesized capacity, any one of the synthesized capacities in the vicinity where the magnitude relationship between the intermediate potential and the reference potential is inverted; a computation unit that computes estimated composite capacities of the capacitor array on the basis of first and second intermediate potentials, which are intermediate potentials when the composite capacities are the first and second composite capacities, respectively; and a derivation unit that derives the capacity of the detection capacitor as a detection capacity on the basis of the estimated combined capacity.

Description

technical field [0001] The invention relates to an electrostatic capacitance detection device. Background technique [0002] Conventionally, a configuration described in Patent Document 1, for example, is known as an electrostatic capacity detection device. This electrostatic capacity detection device has: reference capacity; The detection capacity (capacity to be measured) connected with this reference capacity; The first switch that initializes the reference capacity; The second switch that is arranged between the reference capacity and the detection capacity; an initialized third switch; and a control circuit. After the control circuit initializes the reference capacity based on the operation of the first switch, it performs a plurality of switching operations consisting of the operation of the second switch and the operation of the third switch, and obtains a potential between the reference capacity and the detection capacity, that is, an intermediate potential, Furthe...

Claims

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Application Information

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IPC IPC(8): G01V3/08
CPCG01V3/08H03K17/955H03K17/962H03K2217/960745H03K2217/960705G01R27/2605
Inventor 仓知秀哉高桥昭
Owner AISIN CORP
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