CN218412932U

CN218412932U - Proximity detection circuit and proximity sensor

Info

Publication number: CN218412932U
Application number: CN202222795389.6U
Authority: CN
Inventors: 权锐; 蔡冲; 顾昕; 姜珲
Original assignee: Wuhan Silicon Integrated Co Ltd
Current assignee: Wuhan Silicon Integrated Co Ltd
Priority date: 2022-10-21
Filing date: 2022-10-21
Publication date: 2023-01-31
Anticipated expiration: 2032-10-21

Abstract

The application discloses proximity detection circuit and proximity sensor, this circuit includes: the receiving unit responds to received ambient light to obtain a first photocurrent, and responds to received reflected light and ambient light to obtain a second photocurrent; the control unit is used for controlling the working state of the transmitting unit and controlling the output voltage signal of the integrating unit to be in opposite phase when the transmitting unit switches the states; and the integration unit is used for respectively carrying out integration processing on the first photocurrent and the second photocurrent to obtain a corresponding first output voltage signal and a corresponding second output voltage signal, and obtaining a target voltage signal for proximity detection based on the first output voltage signal and the second output voltage signal. The target voltage signal obtained by the approach detection circuit is a voltage signal obtained after the influence of ambient light is filtered, and the accuracy of an approach detection result can be ensured by determining the distance degree of a target object according to the target voltage signal.

Description

Proximity detection circuit and proximity sensor

Technical Field

The application relates to the technical field of proximity sensors, in particular to a proximity detection circuit and a proximity sensor.

Background

The proximity sensor may detect the presence of an object and the distance of the object from the proximity sensor. The application fields of the proximity sensor are very wide, such as speed detection, manual detection of an automatic faucet, automatic counting or inspection of objects on a conveyor belt, paper edge detection of a printer, and screen-off/lighting control of electronic products.

The photoelectric proximity sensor emits a beam of Light to the outside through a Light-Emitting Diode (LED) or a Vertical Cavity Surface Emitting Laser (VCSEL), the Light is reflected on an object, and the reflected Light is received by a Photodiode (PD) and then converted into a photocurrent signal.

However, since there are many different light sources in the environment, such as sunlight and light, the PD receives not only reflected light but also ambient light, so that the photocurrent is related to not only the reflected light but also the ambient light, and the ambient light mixed in the reflected light interferes with the determination of the distance to the object.

SUMMERY OF THE UTILITY MODEL

The application provides a proximity detection circuit and proximity sensor aims at solving current proximity sensor when detecting the object distance, and ambient light can disturb its judgement to the object degree of nearness, leads to detecting the problem that the precision is low.

In a first aspect, the present application provides a proximity detection circuit, including a receiving unit, a control unit, and an integration unit, where the receiving unit is electrically connected to the integration unit and the control unit, and the receiving unit is configured with a transmitting unit;

the receiving unit is used for responding to the received ambient light to obtain a first photocurrent when the transmitting unit is in a cut-off state, and responding to the received reflected light and the ambient light to obtain a second photocurrent when the transmitting unit is in a light-emitting state; the reflected light is a light signal formed by reflecting detection light emitted by the emission unit in a light-emitting state by a target object;

the control unit is used for controlling the working state of the transmitting unit and controlling the output voltage signal of the integrating unit to be in opposite phase when the transmitting unit switches the state;

and the integrating unit is used for respectively carrying out integration processing on the first photocurrent and the second photocurrent to obtain a corresponding first output voltage signal and a corresponding second output voltage signal, and obtaining a target voltage signal for proximity detection based on the first output voltage signal and the second output voltage signal.

In one possible implementation manner of the present application, the integration unit includes a first operational amplifier and a first integration capacitor, the first integration capacitor is electrically connected between the negative input terminal and the output terminal of the first operational amplifier through a combination switch, and the combination switch is configured to:

when the transmitting unit is in a cut-off state, the first electrode plate of the first integrating capacitor is controlled to be electrically connected with the output end of the first operational amplifier and the second electrode plate of the first integrating capacitor is controlled to be electrically connected with the negative input end of the first operational amplifier in response to a first driving signal of the control unit;

when the emission unit is in a light-emitting state, the first electrode plate of the first integrating capacitor is controlled to be electrically connected with the negative input end of the first operational amplifier and the second electrode plate of the first integrating capacitor is controlled to be electrically connected with the output end of the first operational amplifier in response to a second driving signal of the control unit.

In one possible implementation manner of the present application, the receiving unit includes a first photodiode, a cathode of the first photodiode is connected to a negative input terminal of the first operational amplifier, an anode of the first photodiode is connected to a ground, and the combination switch is configured to:

in response to a first driving signal, the first main switch and the second main switch are closed, and the first auxiliary switch and the second auxiliary switch are turned off;

in response to the second driving signal, the first and second main switches are turned off and the first and second sub switches are turned on.

In one possible implementation manner of the present application, the combination switch includes a first single-pole double-throw switch and a second single-pole double-throw switch, a movable contact of the first single-pole double-throw switch is connected to a second pole plate of the first integrating capacitor, a first stationary contact of the first single-pole double-throw switch is connected to a negative input terminal of the first operational amplifier, and a second stationary contact of the first single-pole double-throw switch is connected to an output terminal of the first operational amplifier;

the movable contact of the second single-pole double-throw switch is connected with the first polar plate of the first integrating capacitor, the first stationary contact of the second single-pole double-throw switch is connected with the output end of the first operational amplifier, and the second stationary contact of the second single-pole double-throw switch is connected with the negative input end of the first operational amplifier.

In one possible implementation manner of the present application, the receiving unit includes a first photodiode, a cathode of the first photodiode is connected to the negative input terminal of the first operational amplifier, an anode of the first photodiode is connected to a ground, and the combination switch is configured to:

responding to a first driving signal, connecting a movable contact of the first single-pole double-throw switch with a first fixed contact of the first single-pole double-throw switch, and connecting a movable contact of the second single-pole double-throw switch with a first fixed contact of the second single-pole double-throw switch;

in response to a second drive signal, the movable contact of the first single-pole double-throw switch is connected with the second fixed contact of the first single-pole double-throw switch, and the movable contact of the second single-pole double-throw switch is connected with the second fixed contact of the second single-pole double-throw switch.

In one possible implementation manner of the present application, the proximity detection circuit further includes a switched capacitor unit and an analog-to-digital conversion unit, and the switched capacitor unit is electrically connected to the integration unit and the analog-to-digital conversion unit respectively;

the switch capacitor unit is used for obtaining an analog signal according to the target voltage signal output by the integrating unit and outputting the analog signal to the analog-to-digital conversion unit;

and the analog-to-digital conversion unit is used for converting the analog signal into a digital signal, and the digital signal is used for representing the proximity degree of the target object.

In one possible implementation manner of the present application, the switched capacitor unit includes a second operational amplifier, a second capacitor, a third capacitor, a second switch, a third switch, and a fourth switch;

the second switch and the second capacitor are connected in series between the output end of the integrating unit and the negative input end of the second operational amplifier, and the second capacitor is also connected with a reference voltage source through a third switch;

the third capacitor and the fourth switch are connected in series between the negative input end of the second operational amplifier and the output end of the second operational amplifier;

the output end of the second operational amplifier is connected with the input end of the analog-to-digital conversion unit.

In a second aspect, the present application further provides a proximity sensor including the proximity detection circuit of the first aspect or any one of the possible implementations of the first aspect.

From the above, the present application has the following advantageous effects:

in the application, when the state of the transmitting unit is switched through the control unit, the output voltage signal of the integrating unit is controlled to be inverted, the first output voltage signal or the second output voltage signal can be inverted, then after the working state of the transmitting unit is switched, the integrating unit carries out integration processing on the second photocurrent or the first photocurrent based on the inverted first output voltage signal or the second output voltage signal, therefore, the target voltage signal finally output by the integrating unit is the voltage signal with the voltage corresponding to the ambient light removed, the approach degree of the target object can be accurately judged through the voltage signal, the approach detection accuracy is improved, and the reliability of the approach detection circuit is ensured.

Drawings

In order to more clearly illustrate the technical solutions in the present application, the drawings that are needed to be used in the description of the present application will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without inventive effort.

FIG. 1 is a schematic diagram of one functional block of a proximity detection circuit provided in an embodiment of the present application;

FIG. 2 is a schematic circuit diagram of an integration unit provided in an embodiment of the present application;

fig. 3 is a schematic circuit diagram of an integrating unit when a transmitting unit is in an off state according to an embodiment of the present application;

fig. 4 is a schematic circuit diagram of an integrating unit when the emitting unit provided in the embodiment of the present application is in a light emitting state;

FIG. 5 is a schematic diagram of one embodiment of a combination switch provided in embodiments of the present application;

fig. 6 is a schematic diagram of a state of the combination switch when the transmitting unit provided in the embodiment of the present application is in an off state;

fig. 7 is a schematic diagram of a state of the combination switch when the emission unit provided in the embodiment of the present application is in a light-emitting state;

FIG. 8 is a timing diagram of a target voltage signal provided in an embodiment of the present application;

FIG. 9 is a schematic diagram of another embodiment of a combination switch provided in an embodiment of the present application;

fig. 10 is a schematic diagram of another state of the combination switch when the transmitting unit provided in the embodiment of the present application is in an off state;

fig. 11 is a schematic view showing another state of the combination switch when the emission unit provided in the embodiment of the present application is in a light-emitting state;

FIG. 12 is a schematic diagram of another functional block of a proximity detection circuit provided in an embodiment of the present application;

FIG. 13 is a schematic circuit diagram of a switched capacitor unit provided in an embodiment of the present application;

FIG. 14 is a timing diagram of the target voltage signal provided in the embodiments of the present application;

FIG. 15 is another timing diagram of the target voltage signal provided in the embodiments of the present application;

FIG. 16 is a schematic diagram of a proximity sensor provided in an embodiment of the present application;

fig. 17 is another schematic structural view of the proximity sensor provided in the embodiment of the present application.

Detailed Description

The technical solutions in the present application will be described clearly and completely with reference to the accompanying drawings in the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, 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 application.

In the description of the present application, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be considered as limiting the present application. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

It is to be noted that "connected" in the embodiments of the present application may be understood as an electrical connection, and the connection of two electrical components may be a direct or indirect connection between the two electrical components. For example, a and B may be connected directly, or indirectly through one or more other electrical components.

In this application, the word "exemplary" is used to mean "serving as an example, instance, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. The following description is presented to enable any person skilled in the art to make and use the application. In the following description, details are set forth for the purpose of explanation. It will be apparent to one of ordinary skill in the art that the present application may be practiced without these specific details. In other instances, well-known structures and processes are not set forth in detail in order to avoid obscuring the description of the present application with unnecessary detail. Thus, the present application is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

The embodiments of the present application provide a proximity detection circuit and a proximity sensor, which are described in detail below.

First, referring to fig. 1, fig. 1 is a schematic diagram of a functional module of a proximity detection circuit provided in an embodiment of the present application, where the proximity detection circuit includes a receiving unit 102, a control unit (not shown in the figure), and an integrating unit 103, where the receiving unit 102 is electrically connected to the integrating unit 103 and the control unit, and the receiving unit 102 is correspondingly configured with a transmitting unit 101.

The receiving unit 102 may be configured to obtain a first photocurrent in response to the received ambient light when the transmitting unit 101 is in an off state, and obtain a second photocurrent in response to the received reflected light and the ambient light when the transmitting unit 101 is in a light emitting state; the reflected light is an optical signal formed by reflecting detection light emitted by the emission unit 101 in a light-emitting state by a target object;

the control unit may be configured to control an operating state of the transmitting unit 101 and control an output voltage signal of the integrating unit 103 to be inverted when the transmitting unit 101 performs state switching;

the integrating unit 103 may be configured to perform integration processing on the first photocurrent and the second photocurrent to obtain a corresponding first output voltage signal and a corresponding second output voltage signal, and obtain a target voltage signal for proximity detection based on the first output voltage signal and the second output voltage signal.

In the embodiment of the present application, the emitting unit 101 may be configured with two operating states, i.e., a light emitting state and an off state, and it can be understood that when the emitting unit 101 is in the light emitting state, the emitting unit 101 may emit the detection light, and when the emitting unit 101 is in the off state, the emitting unit 101 does not emit the light, i.e., no detection light is emitted.

It is understood that the wavelength of the detection light emitted by the emitting unit 101 and the wavelength of the light perceived by the receiving unit 102 may be matched, for example, the detection light emitted by the emitting unit 101 is visible light or a certain visible light range, and the reflected light perceived by the receiving unit 102 is also corresponding visible light or a certain visible light range; if the detection light emitted by the emitting unit 101 is infrared light or a certain invisible light range, the reflected light that can be perceived by the receiving unit 102 is also the corresponding infrared light or a certain invisible light range.

The control unit may control the emission of the detection light by controlling the operating state of the emission unit 101, for example, when the control unit emits a trigger signal to the emission unit 101, the emission unit 101 may be in an emission state in response to the trigger signal, so as to emit the detection light based on a certain emission frequency; when the control unit stops sending the trigger signal to the emitting unit 101, the emitting unit 101 is switched from the emitting state to the cut-off state, so as to stop sending the detection light; when the control unit sends the trigger signal to the emitting unit 101 again, the emitting unit 101 is switched from the off state to the light emitting state in response to the trigger signal, and emits the detection light again.

In this embodiment of the application, the Emitting unit 101 may be a Light source with a Light Emitting function, such as a Light-Emitting Diode (LED) or a Vertical Cavity Surface Emitting Laser (VCSEL), and the specific components of the Emitting unit 101 may be different in different application scenarios, which is not specifically limited herein.

The detection light emitted by the emitting unit 101 may form a reflected light to be emitted to the receiving unit 102 after being reflected by the object, the receiving unit 102 may form a corresponding photocurrent according to the received reflected light, and the proximity of the object may be determined based on the photocurrent, where the proximity may be a distance of the object with respect to a proximity detection circuit, the emitting unit 101, the receiving unit 102, or a predetermined reference point.

In the environment, in addition to the emitting unit 101, there may be other light sources such as the sun and incandescent lamp, and if the wavelength of the light emitted by these light sources, that is, the wavelength of the ambient light, is within the light range that can be sensed by the receiving unit 102, the light is also sensed by the receiving unit 102 to form a corresponding photocurrent, and the photocurrent of the ambient light affects the determination of the proximity of the target object, so when determining the proximity of the target object, the interference of the photocurrent is to be eliminated.

In this embodiment of the application, the receiving unit 102 may obtain a first photocurrent in response to the ambient light when the transmitting unit 101 is in a cut-off state, and the integrating unit 103 may integrate the first photocurrent to obtain a first output voltage signal; when the transmitting unit 101 is in a light emitting state, the receiving unit 102 may obtain a second photocurrent in response to the reflected light and the ambient light, and the integrating unit 103 may integrate the second photocurrent to obtain a second output voltage signal.

When the emitting unit 101 performs state switching, for example, switching from a light emitting state to an off state or from an off state to a light emitting state, the control unit may control the output voltage signal of the integrating unit 103 to be inverted.

For example, if the emitting unit 101 is switched from the off state to the light emitting state, since the integrating unit 103 can obtain the first output voltage signal according to the first photocurrent when the emitting unit 101 is in the off state, the output voltage signal of the integrating unit 103 is the first output voltage signal, and when the control unit controls the emitting unit 101 to switch the states, the control unit can simultaneously control the output voltage signal of the integrating unit 103, that is, the first output voltage signal at this time is inverted.

It is understood that the inversion is relative to the reference voltage, and if the reference voltage is 0V and the amplitude of the first output voltage signal is 5V, the amplitude of the output voltage signal of the integration unit 103 after the inversion is-5V; if the reference voltage is 2V and the amplitude of the first output voltage signal is 5V, the amplitude of the output voltage signal of the integrating unit 103 after phase inversion is-1V, and the value of the reference voltage may be determined according to an actual application scenario, which is not specifically limited herein.

After the first output voltage signal, which is the output voltage signal of the integrating unit 103, is inverted, the emitting unit 101 is in the light emitting state at this time, so that the integrating unit 103 can continue to integrate the second photocurrent based on the inverted first output voltage signal.

It can be understood that the first photocurrent is a photocurrent corresponding to the light intensity of the ambient light, and the second photocurrent is a photocurrent corresponding to the light intensity of both the reflected light and the ambient light, because the environment where the proximity detection circuit is located does not change or changes very little in the detection process, the intensity of the ambient light remains unchanged or the change range is within a controllable detection error range, therefore, the intensities of the ambient light corresponding to the emission unit 101 in the light-emitting state and the cut-off state can be regarded as the same, and it can be known that the amplitude of the first output voltage signal corresponding to the first photocurrent is smaller than the amplitude of the second output voltage signal corresponding to the second photocurrent.

In this embodiment of the application, the integration unit 103 continues to integrate the second photocurrent based on the inverted first output voltage signal, and since the amplitude of the second output voltage signal is greater than the amplitude of the first output voltage signal, the target voltage signal finally output by the integration unit is a difference between the second output voltage signal and the first output voltage signal, and the amplitude of the target voltage signal is greater than the reference voltage.

It can be understood that the difference between the second output voltage signal and the first output voltage signal is a voltage signal obtained by removing the integral voltage corresponding to the ambient light on the basis of the integral voltage corresponding to the reflected light and the ambient light, so that the proximity of the target object can be accurately determined based on the target voltage signal.

It should be noted that, in some other application scenarios, if the emitting unit 101 is switched from the light emitting state to the off state, since the integrating unit 103 can obtain the second output voltage signal according to the second photocurrent when the emitting unit 101 is in the light emitting state, the output voltage signal of the integrating unit 103 is the second output voltage signal, and when the control unit controls the emitting unit 101 to switch the states, the control unit can simultaneously control the output voltage signal of the integrating unit 103, that is, the second output voltage signal at this time is inverted.

After the second output voltage signal, which is the output voltage signal of the integrating unit 103, is inverted, the transmitting unit 101 is in the off state at this time, so that the integrating unit 103 can continue to integrate the first photocurrent based on the inverted second output voltage signal.

At this time, the output voltage signal of the integrating unit 103 is also the difference between the second output voltage signal and the first output voltage signal, and since the amplitude of the second output voltage signal is greater than the amplitude of the first output voltage signal, the target voltage signal output by the integrating unit 103 in this application scenario is a negative value, and the target voltage signal is also a voltage signal obtained after the integrated voltage corresponding to the ambient light is removed, so that the proximity of the target object can be accurately determined based on the target voltage signal.

That is to say, in the embodiment of the present application, the control unit may first control the emitting unit 101 to be in the light emitting state, and then control the emitting unit 101 to be switched from the light emitting state to the cut-off state; or, the control unit may also control the transmitting unit 101 to be in the cut-off state first, and then control the transmitting unit 101 to be converted from the cut-off state to the light-emitting state, and the sequence of the specific working states of the transmitting unit 101 may be determined according to the actual application scenario, which is not limited herein.

It should be noted that, in the embodiment of the present application, no matter whether the emitting unit 101 is switched from the light emitting state to the off state or from the off state to the light emitting state, when the emitting unit 101 switches the states, the output voltage signal of the integrating unit 103 is synchronously controlled to be inverted, the target voltage signal finally output by the integrating unit 103 is the voltage signal obtained after the integrated voltage corresponding to the ambient light is removed, and the proximity of the target object can be determined based on the target voltage signal.

In the embodiment of the application, when the state of the transmitting unit 101 is switched by the control unit, the output voltage signal of the integrating unit 103 is controlled to be inverted, so that the first output voltage signal or the second output voltage signal is inverted, and then after the working state of the transmitting unit 101 is switched, the integrating unit 103 integrates the second photocurrent or the first photocurrent based on the inverted first output voltage signal or the second output voltage signal, so that the target voltage signal finally output by the integrating unit 103 is the voltage signal from which the voltage corresponding to the ambient light is removed, the approach degree of the target object can be accurately determined by the voltage signal, the accuracy of approach detection is improved, and the reliability of the approach detection circuit is ensured.

Next, the details of each unit of the proximity detection circuit shown in fig. 1 and a specific embodiment that may be adopted in practical applications will be described.

In some embodiments of the present application, the control unit may be specifically configured to control a duration of the emitting unit 101 in the light emitting state to be the same as a duration of the emitting unit in the off state in a preset detection period.

It can be understood that the detection period may be any preset time duration, for example, 20ms, 45ms, etc., and since the interference of the ambient light on the determination of the proximity of the target object is to be removed, the difference between the second output voltage signal and the first output voltage signal needs to completely cancel the integration voltage corresponding to the ambient light, so that the integration time duration of the photocurrent corresponding to the ambient light when the emission unit 101 is in the off state and the light emitting state should be the same for the integration unit 103, and therefore, after the integration processing is performed on the second photocurrent and the first photocurrent within the same time duration, the difference between the obtained second output voltage signal and the first output voltage signal is the ideal target voltage signal.

As can be understood from the foregoing description, by integrating the second photocurrent and the first photocurrent for the same time, it can be determined that the time period during which the emission unit 101 does not emit the detection light is the same as the time period during which the emission unit 101 emits the detection light, that is, the time period during which the emission unit 101 is in the off state and the light-emitting state is the same.

In one specific implementation, the durations of the emission unit 101 in the light-emitting state and the cut-off state may equally divide the total duration of the detection period, for example, the detection period is 20ms, and the durations of the emission unit 101 in the light-emitting state and the cut-off state may be 10ms, respectively, for example, the emission unit 101 may be in the cut-off state in the first 10ms of the detection period and in the light-emitting state in the last 10ms of the detection period; alternatively, the emission unit 101 may be in a light emission state for the first 10ms of the detection period and in an off state for the last 10ms of the detection period.

In another specific implementation, the time length of the emitting unit 101 in the light emitting state and the off state may be the time length of the previous part of the detection period, for example, if the detection period is 50ms, the time length of the emitting unit 101 in the off state may be the first 15ms of 50ms, the time length of the emitting unit 101 in the light emitting state may be the next 15ms adjacent to the first 15ms, and after the 15ms of the emitting unit 101 in the light emitting state is ended, the proximity of the target object may be directly determined according to the target voltage signal currently output by the integrating unit 103.

It is understood that the value of the target voltage signal obtained in one detection period may be less convenient for subsequent quantization, and therefore, in some embodiments of the present application, the emission unit 101 may be controlled to perform a state transition between the off state and the light-emitting state in a plurality of consecutive detection periods, so as to accumulate the target voltage signals obtained in a plurality of detection periods, and obtain a larger voltage signal for subsequent quantization.

Referring to fig. 2, fig. 2 is a schematic circuit diagram of an integrating unit provided in the embodiment of the present application, in some embodiments of the present application, the integrating unit 103 may include a first operational amplifier U1 and a first integrating capacitor C1, the first integrating capacitor C1 may be electrically connected between a negative input terminal and an output terminal of the first operational amplifier U1 through a combination switch 104, and the combination switch 104 may be configured to:

when the transmitting unit 101 is in a cut-off state, the first electrode plate of the first integrating capacitor C1 is controlled to be electrically connected with the output end of the first operational amplifier U1 and the second electrode plate of the first integrating capacitor C1 is controlled to be electrically connected with the negative input end of the first operational amplifier U1 in response to the first driving signal of the control unit;

when the emitting unit 101 is in a light emitting state, the first electrode plate of the first integrating capacitor C1 is controlled to be electrically connected to the negative input terminal of the first operational amplifier U1 and the second electrode plate of the first integrating capacitor C1 is controlled to be electrically connected to the output terminal of the first operational amplifier U1 in response to the second driving signal of the control unit.

In the embodiment of the present application, the combination switch 104 can adjust the connection relationship between the first integrating capacitor C1 and the first operational amplifier U1, and since the voltage across the first integrating capacitor C1 cannot suddenly change, when the transmitting unit 101 switches the state, the control unit controls the switching state of the combination switch 104 to adjust the connection relationship between the first integrating capacitor C1 and the first operational amplifier U1, so that the output voltage signal of the first operational amplifier U1 can be inverted when the transmitting unit 101 switches the state.

As shown in fig. 3, in the embodiment of the present application, the first plate of the first integrating capacitor C1 is a right plate thereof, the second plate of the first integrating capacitor C1 is a left plate thereof, and when the transmitting unit 101 is in an off state, the combination switch 104 responds to the first driving signal, so as to connect the left plate of the first integrating capacitor C1 with the negative input terminal of the first operational amplifier U1, and connect the right plate of the first integrating capacitor C1 with the output terminal of the first operational amplifier U1.

As shown in fig. 4, when the transmitting unit 101 is in a light emitting state, the combination switch may connect the left plate of the first integrating capacitor C1 with the output terminal of the first operational amplifier U1 and connect the right plate of the first integrating capacitor C1 with the negative input terminal of the first operational amplifier U1 in response to the second driving signal.

When the transmitting unit 101 is in the cut-off state, the integrating unit 103 integrates the first photocurrent to obtain a first output voltage signal, and therefore, a voltage difference between two ends of the first integrating capacitor C1 is an amplitude of the first output voltage signal, and when the transmitting unit 101 is switched from the cut-off state to the light-emitting state, because a left electrode plate of the first integrating capacitor C1 is connected to a negative input terminal of the first operational amplifier U1 and is changed to be connected to an output terminal of the first operational amplifier U1, and a right electrode plate of the first integrating capacitor C1 is connected to an output terminal of the first operational amplifier U1 and is changed to be connected to a negative input terminal of the first operational amplifier U1, and a voltage between two ends of the first integrating capacitor C1 cannot change suddenly, a charge on the first integrating capacitor C1 remains unchanged, and at this time, the output voltage signal of the first operational amplifier U1 is a voltage signal after inversion of the first output voltage signal.

Then, when the emitting unit 101 is in a light emitting state, the integrating unit 103 continues to integrate the second photocurrent to obtain a second output voltage signal, and after a detection period is finished, the output voltage signal of the first operational amplifier U1 is the difference between the second output voltage signal and the first output voltage signal.

Referring to fig. 5, fig. 5 is a schematic diagram of an embodiment of a combination switch provided in an embodiment of the present application, in some embodiments of the present application, the combination switch 104 may include a main switch pair and a sub switch pair, states of the main switch pair and the sub switch pair are opposite, a first main switch S1a and a second main switch S1a 'of the main switch pair are synchronized, and a first sub switch S1b and a second sub switch S1b' of the sub switch pair are synchronized;

one end of a first main switch S1a is connected with the second pole plate of the first integrating capacitor C1, the other end of the first main switch S1a is connected with the negative input end of the first operational amplifier U1, one end of a second main switch S1a 'is connected with the first pole plate of the first integrating capacitor C1, and the other end of the second main switch S1a' is connected with the output end of the first operational amplifier U1;

one end of the first secondary switch S1b is connected to the second plate of the first integrating capacitor C1, the other end is connected to the output end of the first operational amplifier U1, one end of the second secondary switch S1b' is connected to the first plate of the first integrating capacitor C1, and the other end is connected to the negative input end of the first operational amplifier U1.

In this embodiment, the receiving unit 102 may include a first photodiode D1, a cathode of the first photodiode D1 is connected to the negative input terminal of the first operational amplifier U1, an anode of the first photodiode D1 is connected to the ground GND, and the combination switch 104 is configured to:

in response to a first driving signal, the first main switch S1a and the second main switch S1a 'are closed, and the first sub-switch S1b and the second sub-switch S1b' are turned off;

in response to the second driving signal, the first and second main switches S1a and S1a 'are turned off, and the first and second sub-switches S1b and S1b' are turned on.

Because the current flow direction in the first photodiode D1 is from the cathode to the anode, in this embodiment of the application, the flow directions of the first photocurrent and the second photocurrent are both from the output end of the first operational amplifier to the ground GND through the first integrating capacitor C1 and the first photodiode D1, and therefore the voltage of the right plate of the first integrating capacitor C1 gradually increases, that is, the integrating processing performed by the first operational amplifier U1 on the first photocurrent and the second photocurrent is upward integration.

It can be understood that a control switch S6 may be further connected between the first photodiode D1 and the negative input terminal of the first operational amplifier U1, and when the control switch S6 is turned off, no matter what state the transmitting unit 101 is, no output signal is generated by the first operational amplifier U1 due to the open circuit between the first photodiode D1 and the first operational amplifier U1; when the control switch S6 is closed, the first operational amplifier U1 will generate an output signal.

As shown in fig. 6, in the embodiment of the present application, when the transmitting unit 101 is in an off state, the first main switch S1a and the second main switch S1a 'are closed in response to the first driving signal of the control unit, and since the main switch pair and the sub switch pair are in opposite states, the first sub switch S1b and the second sub switch S1b' are opened, at this time, the first operational amplifier U1 integrates the first photocurrent upwards in a time period when the transmitting unit 101 is in the off state, so as to obtain a first output voltage signal;

then, the control unit controls the transmitting unit 101 to switch from the off state to the light emitting state, and at the same time, as shown in fig. 7, the first sub switch S1b and the second sub switch S1b 'are closed in response to the second driving signal of the control unit, the first main switch S1a and the second main switch S1a' are disconnected, and at the moment of switching the states, because the charge on the first integrating capacitor C1 remains unchanged, the output voltage signal of the first operational amplifier U1 is a signal after the phase inversion of the first output voltage signal;

the first operational amplifier U1 continues to integrate the second photocurrent upwards within the duration that the emitting unit 101 is in the light emitting state, and the starting point value of the integration upwards is the amplitude of the first output voltage signal after the phase inversion, and after a detection period is finished, the output voltage signal of the first operational amplifier U1 is the target voltage signal.

As shown in fig. 8, fig. 8 is a timing diagram of a target voltage signal provided in the present embodiment, a first reset switch RST1 is connected in parallel with a first integrating capacitor C1, before detecting a proximity degree of a target object, the first reset switch RST1 and a control switch S6 may be controlled to be closed first, electric energy originally stored on the first integrating capacitor C1 is consumed by the closed first reset switch RST1, then the first reset switch RST1 is controlled to be opened, and since the control switch S6 is closed, a path is formed between the first photodiode D1 and the first operational amplifier U1, and proximity detection starts when a falling edge of the first reset switch RST1 occurs.

The time duration of the emission unit 101 in the light-emitting state and the cut-off state is set to Δ T, the reflected light is I _ c, and the ambient light is I _ a.

First, the control unit does not send a trigger signal to the transmitting unit 101, the transmitting unit 101 does not emit detection light such as infrared light IR, and at the same time, the control unit sends a first driving signal to control the first main switch S1a and the second main switch S1a 'to be closed, the first sub switch S1b and the second sub switch S1b' to be open, at this time, the left plate of the first integrating capacitor C1 is connected to the negative input end of the first operational amplifier U1, the right plate of the first integrating capacitor C1 is connected to the output end of the first operational amplifier U1, when the transmitting unit 101 is in an OFF state, i.e., IR _ OFF, the first photodiode D1 receives only ambient light I _ a, according to the foregoing description, the integrating unit 103 performs upward integration processing on the first photocurrent, at this time, the voltage of the first integrating capacitor C1 may increase from 0 to Δ V1 within an integration time Δ T based on a slope Slop _ OFF, where slope Slop _ OFF _ I _ a = I/C1, and the first output voltage signal, i.e., Δ V1= i.e., I _ a/C1, increases from a slope V _ OFF to a target voltage VOUT _ op.

When the emitting unit 101 is in an OFF state, that is, the duration of IR _ OFF reaches a preset duration Δ T, the control unit starts to send a trigger signal to the emitting unit 101 to drive the emitting unit 101 to emit detection light to a target object, and at the same time, the control unit sends a second drive signal to control the first sub-switch S1b and the second sub-switch S1b 'to be closed, the first main switch S1a and the second main switch S1a' are opened, at this time, the left electrode plate of the first integrating capacitor C1 is connected to the output end of the first operational amplifier U1, the right electrode plate of the first integrating capacitor C1 is connected to the negative input end of the first operational amplifier U1, and since the charge on the first integrating capacitor C1 remains unchanged, at this time, the output voltage signal of the output end of the first operational amplifier U1 is Δ V1.

When the emitting unit 101 is in a light emitting state, that is, IR _ ON, the first photodiode D1 receives the reflected light I _ C and the ambient light I _ a, the integrating unit 103 performs an upward integration process ON the second photocurrent, and at this time, the electric quantity of the first integrating capacitor C1 may be increased by Δ V2 based ON a slope Slop _ ON within an integration time Δ T from- Δ V1, where the slope Slop _ ON = (I _ C + I _ a)/C1, and the integrated value Δ V2= (I _ C + I _ a) × Δ T/C1, because the light intensities of the ambient light and the reflected light received by the first photodiode D1 are greater than the light intensities when only the ambient light is received within the same integration time period, Δ V2 is greater than Δ V1, and at this time, the output voltage signal Δ V2- Δ V1 of the first operational amplifier U1 is the amplitude of the target voltage signal VOUT from which the influence of the ambient light is removed.

ON the basis that the amplitude of the target voltage signal VOUT is Δ V2- Δ V1, if the emitting unit 101 is continuously controlled to be in the light-emitting state IR _ ON and the cut-OFF state IR _ OFF based ON the above method, after two detection periods, the control unit drives the control switch S6 to be turned OFF, so as to end the approach detection, and the amplitude of the target voltage signal VOUT output by the first operational amplifier U1 is 2 (Δ V2- Δ V1). By quantifying 2 x (Δ V2- Δ V1), the proximity of the target object to the proximity detection circuit can be determined.

It is understood that after N detection periods, the magnitude of the target voltage signal VOUT output by the first operational amplifier U1 is N (Δ V2- Δ V1). By quantifying this N x (Δ V2- Δ V1), the proximity of the target object to the proximity detection circuit can also be determined.

Referring to fig. 9, fig. 9 is a schematic diagram of another embodiment of the combination switch provided in the embodiment of the present application, in some embodiments of the present application, the combination switch 104 may include a first single-pole double-throw switch SW1 and a second single-pole double-throw switch SW2, a moving contact of the first single-pole double-throw switch SW1 is connected to the second pole plate of the first integrating capacitor C1, a first stationary contact of the first single-pole double-throw switch SW1 is connected to the negative input terminal of the first operational amplifier U1, and a second stationary contact of the first single-pole double-throw switch SW1 is connected to the output terminal of the first operational amplifier U1;

a movable contact of the second single-pole double-throw switch SW2 is connected with a first pole plate of the first integrating capacitor C1, a first stationary contact of the second single-pole double-throw switch SW2 is connected with an output end of the first operational amplifier U1, and a second stationary contact of the second single-pole double-throw switch SW2 is connected with a negative input end of the first operational amplifier U1.

in response to a first driving signal, a movable contact of the first single-pole double-throw switch SW1 is connected with a first fixed contact of the first single-pole double-throw switch SW1, and a movable contact of the second single-pole double-throw switch SW2 is connected with a first fixed contact of the second single-pole double-throw switch SW 2;

in response to the second drive signal, the movable contact of the first single pole double throw switch SW1 is connected with the second stationary contact of the first single pole double throw switch SW1, and the movable contact of the second single pole double throw switch SW2 is connected with the second stationary contact of the second single pole double throw switch SW 2.

Since the current flowing inside the first photodiode D1 flows from the cathode to the anode, in this embodiment of the application, the flowing directions of the first photocurrent and the second photocurrent are both from the negative input end of the first operational amplifier U1 to the ground GND through the first photodiode D1, and therefore the voltage of the right plate of the first integrating capacitor C1 gradually increases, that is, the integrating processing performed on the first photocurrent and the second photocurrent by the first operational amplifier U1 is upward integration.

As shown in fig. 10, in the embodiment of the present application, when the transmitting unit 101 is in the off state, the first single-pole double-throw switch SW1 responds to the first driving signal to connect its moving contact with its first stationary contact, the second single-pole double-throw switch SW2 also responds to the first driving signal to connect its moving contact with its first stationary contact, at this time, the left plate of the first integrating capacitor C1 is connected to the negative input terminal of the first operational amplifier U1, the right plate of the first integrating capacitor C1 is connected to the output terminal of the first operational amplifier U1, and the first operational amplifier U1 integrates the first photocurrent upwards within the time period that the transmitting unit 101 is in the off state to obtain the first output voltage signal;

then the control unit controls the transmitting unit 101 to switch from the off state to the light emitting state, and at the same time, as shown in fig. 11, the first single-pole double-throw switch SW1 responds to the second driving signal to connect its moving contact with its second stationary contact, and the second single-pole double-throw switch SW2 responds to the second driving signal to connect its moving contact with its second stationary contact, at this time, the left plate of the first integrating capacitor C1 is connected with the output end of the first operational amplifier U1, the right plate of the first integrating capacitor C1 is connected with the negative input end of the first operational amplifier U1, at the moment of switching the state, because the charge on the first integrating capacitor C1 remains unchanged, the output voltage signal of the first operational amplifier U1 is a signal after the phase inversion of the first output voltage signal;

It can be understood that, when the combination switch 104 is controlled according to the above-mentioned control principle for the first single-pole double-throw switch SW1 and the second single-pole double-throw switch SW2, the timing of the target voltage signal output by the first operational amplifier U1 can refer to the timing diagram shown in fig. 8, and is not described herein again.

Referring to fig. 12, fig. 12 is a schematic diagram of another functional module of the proximity detection circuit provided in the embodiment of the present application, in some embodiments of the present application, the proximity detection circuit may further include a switched capacitor unit 105 and an analog-to-digital conversion unit 106, where the switched capacitor unit 105 may be electrically connected to the integrating unit 103 and the analog-to-digital conversion unit 106, respectively; the switched capacitor unit 105 may be configured to obtain an analog signal according to the target voltage signal output by the integrating unit 103 and output the analog signal to the analog-to-digital converting unit 106; the analog-to-digital conversion unit 106 may be used to convert the analog signal to a digital signal, which is used to characterize the proximity of the target object.

In the embodiment of the present application, the switched capacitor unit 105 can operate by moving charges into and out of the capacitor when the switch is turned on and off, that is, the target voltage signal of the integrating unit 103 can be moved into the switched capacitor unit 105 and moved out from the switched capacitor unit 105 to the analog-to-digital converting unit 106 by turning off and turning on the switch of the switched capacitor unit 105, so that the analog-to-digital converting unit 106 can perform analog-to-digital conversion on the signal.

As shown in fig. 13, fig. 13 is a schematic circuit diagram of a switched capacitor unit provided in the embodiment of the present application, and in some embodiments of the present application, the switched capacitor unit 105 may include a second operational amplifier U2, a second capacitor C2, a third capacitor C3, a second switch S2, a third switch S3, and a fourth switch S4;

the second switch S2 and the second capacitor C2 are connected in series between the output end of the integrating unit 103 and the negative input end of the second operational amplifier U2, and the second capacitor C2 is further connected to a reference voltage source through a third switch S3; the third capacitor C3 and the fourth switch S4 are connected in series between the negative input end of the second operational amplifier U2 and the output end of the second operational amplifier U2; the output of the second operational amplifier U2 is connected to the input of the analog-to-digital conversion unit 106.

In this embodiment of the application, the reference voltage source may be a separate voltage source, or may be the same voltage source as the reference voltage source connected to the positive input terminal of the integrating unit 103, and the reference voltage source may output a first reference voltage signal VREF1; it can be understood that the positive input end of the second operational amplifier U2 may also be connected to a voltage source, the voltage source may output a second reference voltage signal VREF2, and the first reference voltage signal VREF1 and the second reference voltage signal VREF2 may be the same or different, and may be specifically determined according to an actual application scenario.

Referring to fig. 13 and 14, in the embodiment of the present application, the first integrating capacitor C1 is connected in parallel with the first reset switch RST1, before the detection of the proximity degree of the target object is started, the first reset switch RST1 and the control switch S6 may be controlled to be turned on, the electric energy originally stored in the first integrating capacitor C1 is consumed by the turned-on first reset switch RST1, and then the first reset switch RST1 is controlled to be turned off, so that a path is formed between the first photodiode D1 and the first operational amplifier U1 due to the turning-on of the control switch S6, and the approach detection is started when the first reset switch RST1 falls.

Firstly, the control unit does not send a trigger signal to the transmitting unit 101, then the transmitting unit 101 does not send detection light such as infrared light IR, meanwhile, the control unit sends a first driving signal, the combination switch 104 acts in response to the first driving signal, at this time, the left electrode plate of the first integrating capacitor C1 is connected to the negative input end of the first operational amplifier U1, the right electrode plate of the first integrating capacitor C1 is connected to the output end of the first operational amplifier U1, when the transmitting unit 101 is in a cut-OFF state, i.e., IR _ OFF, the first operational amplifier U1 performs upward integration processing on the first photocurrent, at this time, the voltage of the first integrating capacitor C1 can be increased from 0 to Δ V1 within an integration time Δ T, i.e., the target voltage signal VOUT1 is increased from 0 to Δ V1.

When the emitting unit 101 is in the cut-OFF state, that is, the duration of IR _ OFF reaches the preset duration Δ T, the control unit starts to send a trigger signal to the emitting unit 101 to drive the emitting unit 101 to emit the detection light to the target object, and at the same time, the control unit sends a second driving signal, the combination switch 104 responds to the second driving signal to act, at this time, the right plate of the first integrating capacitor C1 is connected to the negative input end of the first operational amplifier U1, the left plate of the first integrating capacitor C1 is connected to the output end of the first operational amplifier U1, and since the charge on the first integrating capacitor C1 remains unchanged, at this time, the output voltage signal at the output end of the first operational amplifier U1, that is, the target voltage signal VOUT1, is inverted from Δ V1 to- Δ V1.

When the emitting unit 101 is in a light emitting state, that is, IR _ ON, the first operational amplifier U1 performs an upward integration process ON the second photocurrent, at this time, the electric quantity of the first integrating capacitor C1 may be increased by Δ V2 from- Δ V1 within an integration time Δ T, and because the light intensity of the ambient light and the reflected light received by the first photodiode D1 is greater than the light intensity when only the ambient light is received within the same integration time period, the output voltage signal Δ V2- Δ V1 of the first operational amplifier U1 is the amplitude of the target voltage signal VOUT1 without the influence of the ambient light at this time.

Based ON the magnitude of the target voltage signal VOUT being Δ V2- Δ V1, the emitting unit 101 is further controlled to be in the OFF state IR _ OFF and the emitting state IR _ ON based ON the above method, and after two detection periods, the control unit drives the control switch S6 to be turned OFF, so as to end the approach detection, where the magnitude of the target voltage signal VOUT1 output by the first operational amplifier U1 is 2 (Δ V2- Δ V1).

Then the control unit controls the fourth switch S4 and the fifth switch S5 to be closed to consume the originally stored electric energy on the third capacitor C3, and then controls the fifth switch S5 to be opened to keep the fourth switch S4 closed;

then the control unit controls the second switch S2 to be closed, the left plate voltage of the second capacitor C2 samples the voltage of the first integrating capacitor C1, the right plate voltage of the second capacitor C2 is the second reference voltage signal VREF2, the voltage of the first integrating capacitor C1 is transferred to the second capacitor C2, the third switch S3 is controlled to be closed while the second switch S2 is opened, at this time, the left plate voltage of the second capacitor C2 samples the second reference voltage signal VREF2 different from the voltage of the first integrating capacitor C1, because the voltage of the second capacitor C2 cannot be suddenly changed, when the second switch S2 is opened and the third switch S3 is closed, the voltage of the second capacitor C2 can be gradually transferred to the third capacitor C3 based on the potential change of the second capacitor C2 and the continuously closed fourth switch S4, so that the voltage signal VOUT2 output by the second operational amplifier U2 is an analog signal, and the analog signal can be quantized to determine the approaching degree of the object distance approaching detection circuit.

As can be known from fig. 14, in this embodiment, the approach degree of the target object can be detected in N detection cycles, the target voltage signal VOUT1 obtained in each detection cycle is accumulated on the first integrating capacitor C1, when the N detection cycles end, the control unit drives the control switch S6 to be turned off, so as to end the approach detection, and the target voltage signal VOUT1 accumulated on the first integrating capacitor C1 can be transferred to the third capacitor C3 through the switched capacitor unit 105, so that if the detection is performed in N detection cycles, the amplitude of the final analog signal VOUT2 is N times the amplitude of the analog signal VOUT2 in a single detection cycle.

Referring to fig. 13 and fig. 15, in the embodiment of the present application, before starting the proximity detection, the control unit may control the fourth switch S4 and the fifth switch S5 to be turned on to consume the electric energy originally stored in the third capacitor C3, and then control the fourth switch S4 to be turned off to maintain the fifth switch S5 to be turned on; then, the control unit controls the first reset switch RST1 and the control switch S6 to be closed, the electric energy originally stored in the first integrating capacitor C1 is consumed through the closed first reset switch RST1, then the first reset switch RST1 is controlled to be opened, and as the control switch S6 is closed, a path is formed between the first photodiode D1 and the first operational amplifier U1, and the approach detection starts to be performed at the falling edge of the first reset switch RST 1.

Firstly, the control unit does not send a trigger signal to the transmitting unit 101, then the transmitting unit 101 does not transmit detection light such as infrared light IR, meanwhile, the control unit sends a first driving signal, the combination switch 104 operates in response to the first driving signal, at this time, the left plate of the first integrating capacitor C1 is connected to the negative input end of the first operational amplifier U1, the right plate of the first integrating capacitor C1 is connected to the output end of the first operational amplifier U1, when the transmitting unit 101 is in a cut-OFF state, i.e., IR _ OFF, the first operational amplifier U1 performs an upward integration process on the first photocurrent, at this time, the voltage of the first integrating capacitor C1 may increase from 0 to Δ V1 within an integration time Δ T, i.e., the target voltage signal VOUT1 increases from 0 to Δ V1.

At this time, when a detection period is over, the control unit controls the control switch S6 to be turned off, the second switch S2 to be turned on to transfer the voltage on the first integrating capacitor C1 to the second capacitor C2, and then controls the second switch S2 to be turned off, and controls the third switch S3, the fourth switch S4 to be turned on and the fifth switch S5 to be turned off while the second switch S2 is turned off, so that a trigger condition is provided for the voltage transfer through the potential change of the second capacitor C2, the voltage transferred to the second capacitor C2 can be gradually transferred to the third capacitor C3, and the voltage signal VOUT2 output by the second operational amplifier U2 is an analog signal; by quantifying the analog signal, the proximity of the target to the proximity detection circuit can be determined.

As can be known from fig. 15, after a detection period passes and the voltage on the first integrating capacitor C1 is transferred to the third capacitor C3, the detection of the next detection period may be continued, so that the voltage on the first integrating capacitor C1 in the next detection period is transferred to the third capacitor C3 again, so that the amplitude of the analog signal VOUT2 at this time is twice the amplitude of the analog signal VOUT2 in the previous detection period, and so on, the voltage on the first integrating capacitor C1 in each detection period is transferred to the third capacitor C3 at the end of the detection period, and therefore if the detection is performed for N detection periods, the amplitude of the final analog signal VOUT2 is N times the amplitude of the analog signal VOUT2 in a single detection period.

It can be understood that, in different application scenarios, the number of detection periods can be selected according to actual conditions, so as to ensure that the proximity of the target object can be accurately judged according to the target voltage signal subsequently.

As shown in fig. 16, fig. 16 is a schematic structural diagram of a proximity sensor provided in an embodiment of the present application, and on the basis of the proximity detection circuit, an embodiment of the present application further provides a proximity sensor 1600, where the proximity sensor 1600 may include a proximity detection circuit in any embodiment corresponding to fig. 1 to 15, and therefore, a specific implementation manner of the proximity sensor 1600 may refer to descriptions of the proximity detection circuit in any embodiment corresponding to fig. 1 to 15 of the present application, and beneficial effects that can be achieved by the proximity detection circuit in any embodiment corresponding to fig. 1 to 15 of the present application may be achieved, for details, see the foregoing description, and are not repeated herein.

As shown in fig. 17, in some embodiments of the present application, the proximity sensor 1600 may include a main control unit 1601 and a driving unit 1602, the main control unit 1601 may control the operating state of the transmitting unit 101 by controlling the driving unit 1602, and the main control unit 1601 may be the same module as the control unit in the foregoing embodiments, or another module different from the control unit in the foregoing embodiments, and may specifically be determined according to an actual application scenario.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and parts that are not described in detail in a certain embodiment may refer to the above detailed descriptions of other embodiments, and are not described herein again.

In a specific implementation, each unit or structure may be implemented as an independent entity, or may be combined arbitrarily to be implemented as one or several entities, and the specific implementation of each unit or structure may refer to the foregoing embodiments, which are not described herein again.

The proximity detection circuit and the proximity sensor provided in the present application are described in detail above, and specific examples are applied herein to explain the principles and embodiments of the present application, and the above description is only used to help understanding the circuit and the core idea of the present application; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manner and the application scope may be changed, and in summary, the content of the present specification should not be construed as a limitation to the present application.

Claims

1. The proximity detection circuit is characterized by comprising a receiving unit, a control unit and an integrating unit, wherein the receiving unit is electrically connected with the integrating unit and the control unit respectively, and the receiving unit is correspondingly provided with a transmitting unit;

the receiving unit is used for responding to the received ambient light to obtain a first photocurrent when the transmitting unit is in a cut-off state, and responding to the received reflected light and the ambient light to obtain a second photocurrent when the transmitting unit is in a light-emitting state; the reflected light is an optical signal formed by reflecting detection light emitted by the emission unit in a light-emitting state through a target object;

the control unit is used for controlling the working state of the emission unit and controlling the output voltage signal of the integration unit to be in opposite phase when the emission unit switches states;

the integration unit is configured to perform integration processing on the first photocurrent and the second photocurrent to obtain a corresponding first output voltage signal and a corresponding second output voltage signal, and obtain a target voltage signal for proximity detection based on the first output voltage signal and the second output voltage signal.

2. The proximity detection circuit of claim 1, wherein the control unit is configured to: and in a preset detection period, controlling the emitting unit to be in the same time length in the light-emitting state and the cut-off state.

3. The proximity detection circuit of claim 1, wherein the integration unit comprises a first operational amplifier and a first integration capacitor, the first integration capacitor being electrically connected between the negative input terminal and the output terminal of the first operational amplifier through a combination switch, the combination switch being configured to:

when the transmitting unit is in a light-emitting state, the first electrode plate of the first integrating capacitor is controlled to be electrically connected with the negative input end of the first operational amplifier and the second electrode plate of the first integrating capacitor is controlled to be electrically connected with the output end of the first operational amplifier in response to a second driving signal of the control unit.

4. The proximity detection circuit according to claim 3, wherein the combination switch includes a pair of main switches and a pair of auxiliary switches, the pair of main switches and the pair of auxiliary switches being in opposite states, and a first main switch and a second main switch of the pair of main switches being synchronized, and a first auxiliary switch and a second auxiliary switch of the pair of auxiliary switches being synchronized;

one end of the first main switch is connected with the second pole plate of the first integrating capacitor, the other end of the first main switch is connected with the negative input end of the first operational amplifier, one end of the second main switch is connected with the first pole plate of the first integrating capacitor, and the other end of the second main switch is connected with the output end of the first operational amplifier;

one end of the first auxiliary switch is connected with the second pole plate of the first integral capacitor, the other end of the first auxiliary switch is connected with the output end of the first operational amplifier, one end of the second auxiliary switch is connected with the first pole plate of the first integral capacitor, and the other end of the second auxiliary switch is connected with the negative input end of the first operational amplifier.

5. The proximity detection circuit according to claim 4, wherein the receiving unit includes a first photodiode, a cathode of the first photodiode is connected to a negative input terminal of the first operational amplifier, an anode of the first photodiode is connected to a ground, the combination switch is configured to:

in response to the first drive signal, the first and second main switches are closed and the first and second auxiliary switches are open;

6. The proximity detection circuit according to claim 3, wherein the combination switch includes a first single-pole double-throw switch and a second single-pole double-throw switch, a moving contact of the first single-pole double-throw switch is connected to the second plate of the first integrating capacitor, a first stationary contact of the first single-pole double-throw switch is connected to the negative input terminal of the first operational amplifier, and a second stationary contact of the first single-pole double-throw switch is connected to the output terminal of the first operational amplifier;

the moving contact of the second single-pole double-throw switch is connected with the first pole plate of the first integrating capacitor, the first stationary contact of the second single-pole double-throw switch is connected with the output end of the first operational amplifier, and the second stationary contact of the second single-pole double-throw switch is connected with the negative input end of the first operational amplifier.

7. The proximity detection circuit according to claim 6, wherein the receiving unit includes a first photodiode, a cathode of the first photodiode is connected to a negative input terminal of the first operational amplifier, an anode of the first photodiode is connected to a ground, the combination switch is configured to:

in response to the first driving signal, the movable contact of the first single-pole double-throw switch is connected with the first fixed contact of the first single-pole double-throw switch, and the movable contact of the second single-pole double-throw switch is connected with the first fixed contact of the second single-pole double-throw switch;

in response to the second driving signal, the movable contact of the first single-pole double-throw switch is connected with the second fixed contact of the first single-pole double-throw switch, and the movable contact of the second single-pole double-throw switch is connected with the second fixed contact of the second single-pole double-throw switch.

8. The proximity detection circuit according to any one of claims 1 to 7, further comprising a switched capacitor unit and an analog-to-digital conversion unit, wherein the switched capacitor unit is electrically connected to the integrating unit and the analog-to-digital conversion unit, respectively;

the switched capacitor unit is used for obtaining an analog signal according to the target voltage signal output by the integrating unit and outputting the analog signal to the analog-to-digital conversion unit;

the analog-to-digital conversion unit is used for converting the analog signal into a digital signal, and the digital signal is used for representing the proximity degree of the target object.

9. The proximity detection circuit according to claim 8, wherein the switched-capacitor unit includes a second operational amplifier, a second capacitor, a third capacitor, a second switch, a third switch, and a fourth switch;

the second switch and the second capacitor are connected in series between the output end of the integrating unit and the negative input end of the second operational amplifier, and the second capacitor is also connected with a reference voltage source through the third switch;

and the output end of the second operational amplifier is connected with the input end of the analog-to-digital conversion unit.

10. A proximity sensor, characterized in that it comprises a proximity detection circuit according to any of claims 1-9.