CN114095005A - Capacitive proximity sensor circuit based on photodiode multiplexing - Google Patents
Capacitive proximity sensor circuit based on photodiode multiplexing Download PDFInfo
- Publication number
- CN114095005A CN114095005A CN202111445848.1A CN202111445848A CN114095005A CN 114095005 A CN114095005 A CN 114095005A CN 202111445848 A CN202111445848 A CN 202111445848A CN 114095005 A CN114095005 A CN 114095005A
- Authority
- CN
- China
- Prior art keywords
- photodiode
- switch
- proximity sensor
- circuit
- capacitance detection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
- H03K17/945—Proximity switches
- H03K17/955—Proximity switches using a capacitive detector
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
- H03K17/941—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated using an optical detector
Landscapes
- Electronic Switches (AREA)
- Geophysics And Detection Of Objects (AREA)
Abstract
本发明公开了基于光电二极管复用的电容式接近传感器电路，包括光电二极管、运算放大器、电容检测电路和切换开关；所述光电二极管通过切换开关分别连接运算放大器和电容检测电路；所述光电二极管用于检测人体PPG信号；所述运算放大器可配置放大倍数，用于对PPG信号进行放大；其反相输入端连接光电二极管的阴极，正相输入端接地；所述电容检测电路用于电容的变化进行检测；所述切换开关用于切换电路执行线路，进行光电信号检测与电容变化检测之间的切换。本发明成本低廉，方便实用；能运用在一个传感器上即可实现识别接近的物体是否为人体。
The invention discloses a capacitive proximity sensor circuit based on photodiode multiplexing, comprising a photodiode, an operational amplifier, a capacitance detection circuit and a switch; the photodiode is respectively connected to the operational amplifier and the capacitance detection circuit through a switch; the photodiode is connected to the operational amplifier and the capacitance detection circuit respectively; It is used to detect human PPG signals; the operational amplifier can be configured with a magnification factor to amplify the PPG signal; its inverting input terminal is connected to the cathode of the photodiode, and the non-inverting input terminal is grounded; the capacitance detection circuit is used for capacitance detection. The change is detected; the switch is used for switching the circuit execution circuit to switch between photoelectric signal detection and capacitance change detection. The invention has low cost, is convenient and practical, and can be used on one sensor to realize whether the approaching object is a human body.
Description
Technical Field
The invention relates to the technical field of sensors, in particular to a capacitive proximity sensor circuit based on photodiode multiplexing.
Background
A photosensor is a device that converts an optical signal into an electrical signal. The working principle is based on the photoelectric effect. The photoelectric effect refers to the phenomenon that when light irradiates on some substances, electrons of the substances absorb the energy of photons, and the corresponding electric effect occurs. Photoelectric effects are classified into three categories according to their phenomena: external photoelectric effect, internal photoelectric effect and photovoltaic effect. The photoelectric devices comprise a photoelectric tube, a photomultiplier, a photoresistor, a photosensitive diode, a photosensitive triode, a photoelectric cell and the like. The performance and characteristic curve of the photoelectric device are analyzed.
Among them, a photodiode is the most common photosensor. The shape of the photosensitive diode is the same as that of a common diode, and when no light is emitted, the photosensitive diode has the same shape as that of the common diode, and the reverse current is very small and is called as the dark current of the photosensitive diode; when light is applied, the carriers are excited, creating electron-holes, known as photocarriers. Under the action of an external electric field, the photo-carriers participate in conduction, forming a reverse current much larger than the dark current, which is called photocurrent. The magnitude of the photocurrent is proportional to the intensity of the light, so that an electrical signal varying with the intensity of the light is obtained at the load resistance.
A photodiode, also called a photodiode, is a photodetector that can convert light into a current or voltage signal depending on the mode of use. The die usually uses a PN junction with photosensitive characteristics, which is very sensitive to light changes, has unidirectional conductivity, and changes electrical characteristics when light intensity is different, so that the current in the circuit can be changed by using the intensity of light. Photodiodes have been widely used in medical applications, such as X-ray computed tomography imaging and pulse detectors.
The detection of human body motion heart rate by using a photoplethysmography (PPG) technology is an application of an infrared nondestructive detection technology in biomedicine. The heart rate is calculated from the obtained pulse waveform by utilizing a photoelectric sensor to detect the difference of the reflected light intensity after the absorption of blood and tissues of a human body, tracing the change of the volume of a blood vessel in a cardiac cycle.
A proximity sensor is a device capable of sensing the proximity of an object, and recognizes the proximity of the object by using the sensitivity of a displacement sensor to the approaching object and outputs a corresponding switch signal, and thus, the proximity sensor is also generally called a proximity switch. It is a generic name of a sensor for the purpose of not touching an object to be detected, instead of a contact detection type detection method such as a switch, and it can detect movement and presence information of an object and convert it into an electric signal. The proximity sensor mainly comprises a capacitive proximity sensor, an inductive proximity sensor and a photoelectric proximity sensor. The capacitive proximity sensor is a capacitive proximity switch with electrodes as detection ends and comprises a high-frequency oscillation circuit, a detection circuit, an amplification circuit, a shaping circuit and an output circuit.
At present, most photoelectric sensors and proximity sensor products in the market can only execute a photoelectric sensing function and a proximity sensing function independently, and cannot execute the two functions simultaneously; and has the following problems.
1. The photoelectric sensor can only receive the photoelectric signal and cannot perform the approaching judgment capability;
2. the proximity sensor can only judge whether the human body is close or not and cannot identify whether the human body is close or not;
3. if two functions need to be executed simultaneously, two sensors need to be installed, and the problem of cost increase exists.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a capacitance type proximity sensor circuit based on photodiode multiplexing.
The purpose of the invention is realized by the following technical scheme:
the capacitance type proximity sensor circuit based on the multiplexing of the photodiode comprises the photodiode, an operational amplifier, a capacitance detection circuit and a change-over switch; the photodiode is respectively connected with the operational amplifier and the capacitance detection circuit through the change-over switch.
Further, the photodiode is used for detecting a human body PPG signal.
Further, the operational amplifier may configure an amplification factor for amplifying the PPG signal.
Further, the capacitance detection circuit is used for detecting the change of the capacitance.
Further, the switch is used for switching the circuit execution circuit to switch between photoelectric signal detection and capacitance change detection.
Further, the change-over switch is composed of three common switches, including a first switch, a second switch and a third switch.
Further, the first switch is arranged between the photodiode and the operational amplifier, one end of the first switch is connected with the inverting input end of the operational amplifier, and the other end of the first switch is connected with the cathode of the photodiode.
Furthermore, the second switch is arranged between the photodiode and the capacitance detection circuit, one end of the second switch is connected with the capacitance detection circuit, and the other end of the second switch is connected with the cathode of the photodiode.
Further, the third switch is arranged between the photodiode and the capacitance detection circuit, one end of the third switch is connected with the capacitance detection circuit, and the other end of the third switch is connected with the anode of the photodiode.
Further, the anode of the photodiode is provided with a grounding switch; the grounding switch and the third switch are connected in parallel to the photodiode.
The invention has the beneficial effects that: the invention has low cost, convenience and practicability; the method can be applied to a sensor to realize the identification of whether an approaching object is a human body.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a circuit schematic of the present invention.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In this embodiment, as shown in fig. 1, the capacitance proximity sensor circuit based on photodiode multiplexing includes a photodiode, an operational amplifier, a capacitance detection circuit, and a change-over switch; the photodiode is respectively connected with the operational amplifier and the capacitance detection circuit through the change-over switch.
In this embodiment, the photodiode is used for detecting a PPG signal of a human body.
In this embodiment, the operational amplifier may configure an amplification factor for amplifying the PPG signal.
In this embodiment, the capacitance detection circuit is used for detecting a change in capacitance.
In this embodiment, the switch is used for switching the circuit execution circuit to perform switching between the photoelectric signal detection and the capacitance change detection.
In this embodiment, the switch is composed of three general switches, including a first switch, a second switch, and a third switch.
In this embodiment, the first switch is disposed between the photodiode and the operational amplifier, and has one end connected to the inverting input terminal of the operational amplifier and the other end connected to the cathode of the photodiode.
In this embodiment, the second switch is disposed between the photodiode and the capacitance detection circuit, and has one end connected to the capacitance detection circuit and the other end connected to the cathode of the photodiode.
In this embodiment, the third switch is disposed between the photodiode and the capacitance detection circuit, and has one end connected to the capacitance detection circuit and the other end connected to an anode of the photodiode.
In the embodiment, the anode of the photodiode is provided with a grounding switch; the grounding switch and the third switch are connected in parallel to the photodiode.
The photodiode and the operational amplifier are used for receiving and amplifying the ppg signal of the human body. The change-over switch is used for switching the mode into capacitance detection when needed, and the positive electrode and the negative electrode of the photodiode are used for forming electrodes to measure the capacitance of the proximity conductor. The circuit diagram is shown in fig. 1. Firstly, when photoelectric detection or photoelectric signal receiving is carried out, a first switch connected with a 6-pin (the inverting input of an arithmetic unit) and a grounding switch are closed and conducted, two switches (a second switch and a third switch) at a capacitance detection circuit are disconnected, at the moment, capacitance detection (approaching sensing function) does not work, a photodiode detects light, and a received signal is delivered to an operational amplifier for amplification.
Secondly, when constant volume detection (approach sensing function) is carried out, a first switch connected with a 6 pin (the inverting input of an arithmetic unit) and a grounding switch are disconnected, and two switches at a capacitance detection position are closed. The metal polar plates required by the capacitance detection function are provided by the upper and lower polar plates of the photodiode, so that the capacitance detection function is realized.
The invention multiplexes two metal electrodes of the photodiode, combines capacitance detection, realizes the function of a capacitance proximity sensor and can judge whether a proximity object is a human body.
The invention has low cost, convenience and practicability; the method can be applied to a sensor to realize the identification of whether an approaching object is a human body.
The structures, functions, and connections disclosed herein may be implemented in other ways. For example, the embodiments described above are merely illustrative, e.g., multiple components may be combined or integrated with another component; in addition, functional components in the embodiments herein may be integrated into one functional component, or each functional component may exist alone physically, or two or more functional components may be integrated into one functional component.
The foregoing is illustrative of the preferred embodiments of this invention, and it is to be understood that the invention is not limited to the precise form disclosed herein and that various other combinations, modifications, and environments may be resorted to, falling within the scope of the concept as disclosed herein, either as described above or as apparent to those skilled in the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. The capacitance type proximity sensor circuit based on the multiplexing of the photodiode is characterized by comprising the photodiode, an operational amplifier, a capacitance detection circuit and a change-over switch; the photodiode is respectively connected with the operational amplifier and the capacitance detection circuit through the change-over switch.
2. The photodiode-multiplexing based capacitive proximity sensor circuit of claim 1, wherein the photodiode is configured to detect a human PPG signal.
3. The photodiode multiplexing based capacitive proximity sensor circuit of claim 1, wherein the operational amplifier is configurable with a magnification factor for amplifying the PPG signal; the inverting input end of the photoelectric diode is connected with the cathode of the photoelectric diode, and the non-inverting input end of the photoelectric diode is grounded.
4. The photodiode multiplexing based capacitive proximity sensor circuit of claim 1, wherein the capacitance detection circuit is configured to detect a change in capacitance.
5. The photodiode multiplexing based capacitive proximity sensor circuit of claim 1, wherein the switch is configured to switch a circuit implementation line for switching between photo signal detection and capacitance change detection.
6. The photodiode multiplexing based capacitive proximity sensor circuit of claim 1, wherein the toggle switch is comprised of three common switches including a first switch, a second switch, and a third switch.
7. The photodiode multiplexing based capacitive proximity sensor circuit of claim 6, wherein the first switch is disposed between the photodiode and the operational amplifier, one end of the first switch is connected to the inverting input of the operational amplifier, and the other end of the first switch is connected to the cathode of the photodiode.
8. The photodiode multiplexing based capacitive proximity sensor circuit of claim 6, wherein the second switch is disposed between the photodiode and the capacitance detection circuit, and has one end connected to the capacitance detection circuit and the other end connected to a cathode of the photodiode.
9. The photodiode multiplexing based capacitive proximity sensor circuit of claim 6, wherein the third switch is disposed between the photodiode and the capacitance detection circuit, and has one end connected to the capacitance detection circuit and the other end connected to an anode of the photodiode.
10. The photodiode multiplexing based capacitive proximity sensor circuit of claim 1, wherein an anode of the photodiode is provided with a ground switch; the grounding switch and the third switch are connected in parallel to the photodiode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111445848.1A CN114095005A (en) | 2021-11-30 | 2021-11-30 | Capacitive proximity sensor circuit based on photodiode multiplexing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111445848.1A CN114095005A (en) | 2021-11-30 | 2021-11-30 | Capacitive proximity sensor circuit based on photodiode multiplexing |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114095005A true CN114095005A (en) | 2022-02-25 |
Family
ID=80306016
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111445848.1A Pending CN114095005A (en) | 2021-11-30 | 2021-11-30 | Capacitive proximity sensor circuit based on photodiode multiplexing |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114095005A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117081566A (en) * | 2023-08-31 | 2023-11-17 | 深圳市华怡丰科技有限公司 | Capacitive proximity sensor circuit |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104207761A (en) * | 2013-06-03 | 2014-12-17 | 飞比特公司 | Heart rate data collection |
| CN109196525A (en) * | 2017-07-18 | 2019-01-11 | 深圳市汇顶科技股份有限公司 | Refuse the anti-spoofing sensing of false fingerprint pattern in optical sensor module under the screen for shielding upper fingerprint sensing |
| CN110413134A (en) * | 2018-04-26 | 2019-11-05 | Oppo广东移动通信有限公司 | Wearing state detection method and related equipment |
| CN111670005A (en) * | 2018-02-01 | 2020-09-15 | 三星电子株式会社 | Electronic device for sensing biometric information and control method thereof |
-
2021
- 2021-11-30 CN CN202111445848.1A patent/CN114095005A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104207761A (en) * | 2013-06-03 | 2014-12-17 | 飞比特公司 | Heart rate data collection |
| CN109196525A (en) * | 2017-07-18 | 2019-01-11 | 深圳市汇顶科技股份有限公司 | Refuse the anti-spoofing sensing of false fingerprint pattern in optical sensor module under the screen for shielding upper fingerprint sensing |
| CN111670005A (en) * | 2018-02-01 | 2020-09-15 | 三星电子株式会社 | Electronic device for sensing biometric information and control method thereof |
| CN110413134A (en) * | 2018-04-26 | 2019-11-05 | Oppo广东移动通信有限公司 | Wearing state detection method and related equipment |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117081566A (en) * | 2023-08-31 | 2023-11-17 | 深圳市华怡丰科技有限公司 | Capacitive proximity sensor circuit |
| CN117081566B (en) * | 2023-08-31 | 2024-05-10 | 深圳市华怡丰科技有限公司 | Capacitive proximity sensor circuit |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101551420B (en) | A MEMS device weak capacitance detection circuit | |
| CN217216539U (en) | Capacitive proximity sensor circuit based on photodiode multiplexing | |
| CN111207843B (en) | A pyroelectric sensor with ambient light detection function | |
| CN203933547U (en) | A kind of micro-amplification circuit of electrical signal for handheld device | |
| CN102620756A (en) | Phase sensitive demodulator (PSD) signal single-channel processing method based on modulated laser, and processing circuit | |
| CN114095005A (en) | Capacitive proximity sensor circuit based on photodiode multiplexing | |
| CN110338776A (en) | PPG signal acquisition chip and device based on CMOS integrated circuit technique | |
| CN107980208A (en) | Signaling conversion circuit, heart rate sensor and electronic equipment | |
| CN206117673U (en) | Infrared receiver circuit | |
| CN204027698U (en) | A kind of photodetector with two-stage enlarging function | |
| Huang et al. | Real-time ultraviolet flame detection system based on 4H-SiC phototransistor | |
| CN107328473A (en) | A kind of Electro-Optical Sensor Set | |
| CN113008748A (en) | Infrared detection circuit | |
| TWI527456B (en) | Array read device, dual function read device and detection circuit | |
| CN116026215A (en) | Light spot position detection system based on graphene-germanium-based position sensitive detector | |
| CN206835056U (en) | A kind of collection amplifying circuit based on APD | |
| CN214793487U (en) | Photoelectric detection circuit with high signal-to-noise ratio | |
| CN207586308U (en) | A kind of measuring circuit for acquiring bi-directional voltage signal | |
| CN114910164A (en) | Novel near-infrared single photon detection system | |
| CN114705290A (en) | Superconducting single photon imaging circuit and method based on capacitance feedback | |
| TWI245888B (en) | Detector and method thereof for detecting intensity of ultraviolet rays within different frequency ranges | |
| CN206891928U (en) | A kind of FSC reception systems of flow cytometer | |
| CN206920019U (en) | A kind of photoelectric detective circuit | |
| Li et al. | Design of Photodiode Circuit Based on Signal Acquisition | |
| CN218444170U (en) | Circuit and detection device for improving detection sensitivity of pyroelectric infrared sensor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |