TWI699096B - Method for ambient light subtraction - Google Patents

Abstract

A method for ambient light subtraction providing a sensor having an emitter, a receiver, and a processor; performing a first sampling process, during which the emitter does not emit signals, the receiver receives a first ambient light signal converted into a first data set by the processor; performing a second sampling process, during which the emitter emits a detecting signal, the receiver receives a second ambient light signal and the detecting signal converted into a second data set by the processor; performing a third sampling process, during which the emitter does not emit signals, the receiver receives a third ambient light signal converted into a third data set by the processor; deriving an average value by calculating the average of the first data set and the third data set; and deriving a difference value by calculating the difference between the second data set and the average value.

Description

Ambient light filtering method

The invention relates to a noise elimination method, in particular to an ambient light filtering method.

An active sensor is a sensor that can detect nearby objects without actual contact. The principle is that a transmitter in the sensor emits electromagnetic fields or electromagnetic radiation, and a receiver in the sensor detects Measure changes in the electromagnetic field or receive electromagnetic radiation reflected by the object to be measured.

Active sensors have a wide range of applications. Proximity sensors are a type of active sensors, which are often used in smart phones. They can sense the user’s ears, face, and hair during a call. Turn off the screen touch function temporarily when the parts are close to the screen to prevent these parts from accidentally touching the screen and affecting the call. In addition, proximity sensors can also be used to monitor vibrations inside mechanical devices, entrances and exits of parking lots, conveyors, etc.

The proximity sensor has the advantages of high reliability, long service life, etc., because it does not require complicated structures and mechanical parts, and it does not need to actually touch the object to be tested when it is acting. However, there is more or less ambient light in any detection scene, and ambient light is also electromagnetic radiation, so it may reduce the sensitivity of the receiver to the detection signal, make the receiver reach saturation current early, or affect the object under test. Reflective nature, so ambient light tends to reduce the effect of proximity sensing.

The technical problem to be solved by the present invention is to provide an ambient light filtering method in view of the deficiencies of the prior art, which performs a method before and after detecting the object to be tested. Sub-ambient light detection, calculates the average value of the data obtained from the two ambient light detections and subtracts the average value from the data obtained from the detection of the object to be tested. In this way, the environmental light filtering effect can be improved.

In order to solve the above technical problems, one of the technical solutions adopted by the present invention is to provide an ambient light filtering method, which includes: providing a sensing module, the sensing module including a transmitter, a receiver And a processor; for a first sampling time, the transmitter does not transmit a signal, the receiver receives a first ambient light signal, and the processor converts the first ambient light signal into a first Data; in a second sampling time, the transmitter emits a detection signal, the receiver receives a second ambient light signal and the detection signal, and the processor will be the second ambient light The signal and the detection signal are converted into a second data; during a third sampling time, the transmitter does not transmit a signal, the receiver receives a third ambient light signal, and the processor converts the first Convert three ambient light signals into a third data; calculate the average of the first data and the third data to obtain an average value; and calculate the difference between the second data and the average value to obtain A difference.

One of the beneficial effects of the present invention is that the ambient light filtering method provided by the present invention can pass "a first sampling time, the transmitter does not emit a signal, and the receiver receives a first ambient light Signal, and the processor converts the first ambient light signal into a first data", "in a second sampling time, the transmitter transmits a detection signal, and the receiver receives a second environment Light signal and the detection signal, and the processor converts the second ambient light signal and the detection signal into a second data" and "a third sampling time, the transmitter does not transmit Signal, the receiver receives a third ambient light signal, and the processor converts the third ambient light signal into a third data" technical solution to calculate the first data and the third data The two are averaged to obtain an average value, and the difference between the second data and the average value is calculated to obtain a difference.

In order to further understand the features and technical content of the present invention, please refer to the following Regarding the detailed description and drawings of the present invention, the drawings provided are only for reference and description, and are not used to limit the present invention.

S‧‧‧sensing module

E‧‧‧ transmitter

D‧‧‧Receiver

C‧‧‧Processor

R‧‧‧register

N‧‧‧Detection signal

M‧‧‧Object to be tested

1 is a flowchart of an ambient light filtering method according to an embodiment of the present invention; FIG. 2 is a schematic cross-sectional view of a sensing module provided by the ambient light filtering method according to an embodiment of the present invention when detecting an object to be measured; FIG. 3 It is a functional block diagram of a sensing module provided by an ambient light filtering method according to an embodiment of the present invention; FIG. 4 is a flowchart of an ambient light filtering method according to another embodiment of the present invention.

The following is a specific embodiment to illustrate the implementation of the "ambient light filtering method" disclosed in the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be based on different viewpoints and applications, and various modifications and changes can be made without departing from the spirit of the present invention. In addition, the drawings of the present invention are merely schematic illustrations, and are not drawn according to actual dimensions, and are stated in advance. The following embodiments will further describe the related technical content of the present invention in detail, but the disclosed content is not intended to limit the protection scope of the present invention.

[Example]

1 to 3, the ambient light filtering method of the embodiment of the present invention includes step S100: providing a sensing module S, the sensing module S includes a transmitter E, a receiver D and a processing器P. The present invention does not limit the implementation of the sensing module S, the transmitter E, and the receiver D. For example, in this embodiment, the sensing module S can be a proximity sensor, and the transmitter E and the receiver D are respectively It is a light emitting diode and a photodiode. The light emitting diode emits a detection signal N. The detection signal N is reflected by an object M and received by the photodiode. However, in other embodiments , The sensing module S can also be other types of active sensors, and the transmitter E can also be other types The optical transmitter, such as a laser emitter, and the receiver D can also be other types of optical sensors.

Next, the ambient light filtering method of this embodiment further includes step S102: for a first sampling time, the transmitter E does not transmit a signal, the receiver D receives a first ambient light signal, and the processor P receives the first ambient light signal The light signal is converted into a first data; Step S104: In a second sampling time, the transmitter E transmits a detection signal N, the receiver D receives a second ambient light signal and the detection signal N, and the processor P The second ambient light signal and the detection signal N are converted into a second data; step S106: during a third sampling time, the transmitter E does not transmit a signal, the receiver D receives a third ambient light signal, and the processor P The third ambient light signal is converted into a third data.

In detail, the first sampling time, the second sampling time, and the third sampling time occur in time sequence, that is, the ambient light filtering method of the present invention actually sends out the detection signal N to detect the under-measurement on the photodiode E Before the object M, the ambient light signal is sampled once, and after the photodiode E detects the object M, the ambient light signal is sampled again. Furthermore, the detection signal N refers to a signal sent by the transmitter E and reflected by the object M and received by the receiver D. The receiver D can determine whether the object exists or not through the detection signal N it receives.

Next, the ambient light filtering method of this embodiment further includes step S108: Calculate the average of the first data and the third data to obtain an average; Step S110: Calculate the difference between the second data and the average to obtain A difference. By taking the average value of the first sampling data and the third sampling data, after subtracting the above average value from the second sampling data, the ambient light filtering method of the present invention can effectively eliminate the influence of ambient light on the sensing module S The influence of sensing effect.

Specifically, the prior art environmental light filtering methods mostly do two samplings, in which the transmitter does not send a signal during the first sampling, so that the first sampling data only includes the ambient light signal, and the second sampling When the transmitter emits the detection signal, the second sampling data includes the ambient light signal and the detection signal, and finally the difference between the first and second sampling data is obtained to eliminate the influence of the ambient light on the detection signal influences. Ran However, if the ambient light is eliminated in this way in the prior art, the effect is limited, and the flicker noise in the ambient light still causes signal mismatch to a certain extent, which affects the detection of the object under test.

More specifically, the largest factor affecting sensor detection in ambient light is flicker noise, and the ambient light filtering method of the present invention can effectively reduce 90% compared with the prior art ambient light filtering method. Therefore, the influence of ambient light on the sensing module S can be reduced.

Further, in this embodiment, the processor P is an analog-to-digital converter, and the above average value and difference are calculated by using the analog-to-digital converter. However, the present invention is not limited to this. In other embodiments, the processor P may also be other types of analog signal processors.

In detail, in this embodiment, when the detection signal N is incident on the proximity sensor, the photodiode and photons cause the electrons and holes in the photodiode to combine to generate a photoelectric effect, thereby generating a photocurrent Signal, the photocurrent signal is converted into an alternating current analog signal through a conversion step and output to the analog-to-digital converter. Then, the analog-to-digital converter converts the analog signal into a digital signal.

The present invention does not limit the conversion of the photocurrent signal to the analog signal and the conversion of the analog signal to the digital signal. For example, it may be a Fourier transform, and those skilled in the art can choose an appropriate conversion method according to the needs and applications.

Furthermore, the sensing module S further includes a register R. The processor P converts the first ambient light signal according to the number of sampling information and the pulse number information stored in the register R Convert the first data, the second ambient light signal, and the reflected signal into the second data, and convert the third ambient light signal into the third data.

In detail, one sampling includes three samplings. In other words, in this embodiment, the first data is acquired in the first sampling time, the second data is acquired in the second sampling time, and the third data is acquired in the third sampling time. It is called a sampling. The pulse number information refers to the total number of pulses included in the distance from the sensing module S to the object M. According to the sampling frequency information and pulse wave information stored in the register R, the first environment The light signal, the second ambient light signal, the detection signal, and the third ambient light signal are integrated into first data, second data, and third data that can be operated on.

In different embodiments, the ambient light filtering method includes the following steps. In step S200, a sensing module S is provided. The sensing module S includes a transmitter E, a receiver D, and a processor P. In step S202, during a first sampling time, the transmitter E does not transmit a signal, the receiver D receives a first ambient light signal, and the processor P converts the first ambient light signal into a first data. In step S204, during a second sampling time, the transmitter E transmits a detection signal N, the receiver D receives a second ambient light signal and the detection signal N, and the processor P combines the second ambient light signal with The detection signal N is converted into a second data. In step S206, during a third sampling time, the transmitter E does not transmit a signal, the receiver D receives a third ambient light signal, and the processor P converts the third ambient light signal into third data. In step S208, during a fourth sampling time, the transmitter E does not transmit a signal, the receiver D receives the fourth ambient light signal, and the processor P converts the fourth ambient light signal into a fourth data. In step S210, during the fifth sampling time, the transmitter E transmits a detection signal N, the receiver D receives the fifth ambient light signal and the detection signal N, and the processor P combines the fifth ambient light signal with the detection signal The signal N is converted into a fifth data.

Specifically, during the execution of the first sampling, the second sampling, the third sampling, the fourth sampling, and the fifth sampling, the pulse number information (Npulse) is equal to 1. In other words, within the distance range from the sensing module S to the object M, one sampling includes five samplings.

Then, the ambient light filtering method of this embodiment further includes step S212, calculating the average of the first data, the third data, and the fifth data to obtain the first average value. In step S214, the average of the second data and the fourth data is calculated to obtain the second average value. In step S216, the difference between the first average value and the second average value is obtained. Using the first average value of the first data, the third data, and the fifth data, and the second average value of the second data and the fourth data, the second average value is subtracted from the first average value. The ambient light of the present invention The filtering method can effectively eliminate the influence of ambient light on the sensing effect of the sensing module S.

[Beneficial effects of the embodiment]

One of the beneficial effects of the present invention is that the ambient light filtering method provided by the present invention can pass "a first sampling time, the transmitter E does not transmit a signal, and the receiver D receives a first ambient light signal, and The processor P converts the first ambient light signal into a first data", "a second sampling time, the transmitter E transmits a detection signal N, and the receiver D receives a second ambient light signal and the detection signal N , And the processor P converts the second ambient light signal and the detection signal N into a second data" and "a third sampling time, the transmitter E does not transmit a signal, and the receiver D receives a third ambient light signal, And the processor P converts the third ambient light signal into a technical feature of a third data" to calculate the average of the first data and the third data to obtain an average value, and calculate the difference between the second data and the average value. A difference is obtained. Or in different embodiments, five data are obtained by sampling five times, and the first average value of the first data, the third data and the fifth data and the second average value of the second data and the fourth data are calculated, and then The second average value is subtracted from the first average value to obtain a difference. Thereby, the ambient light filtering method of the present invention can reduce 90% of flicker noise, thereby effectively reducing the influence of ambient light on the sensing effect of the sensing module S.

The content disclosed above is only the preferred and feasible embodiments of the present invention, and does not limit the scope of the patent application of the present invention. Therefore, all equivalent technical changes made using the content of the description and drawings of the present invention are included in the application of the present invention. Within the scope of the patent.

The designated representative diagram is a flowchart, so it is simply explained without symbols.

Claims (10)

An ambient light filtering method, comprising: providing a sensing module, the sensing module including a transmitter, a receiver and a processor; within a first sampling time, the transmitter does not transmit Signal, the receiver receives a first ambient light signal, and the processor converts the first ambient light signal into a first data; in a second sampling time, the transmitter emits a detection signal , The receiver receives a second ambient light signal and the detection signal, and the processor converts the second ambient light signal and the detection signal into a second data; a third sampling time Inside, the transmitter does not transmit a signal, the receiver receives a third ambient light signal, and the processor converts the third ambient light signal into a third data; calculates the first data and the Average the two third data to obtain an average value; and calculate the difference between the second data and the average value to obtain a difference. The ambient light filtering method according to claim 1, wherein the processor is an analog-to-digital converter, and the average value and the difference value are calculated by using the analog-to-digital converter. The method for filtering ambient light according to claim 2, wherein the sensing module further includes a register. The method for filtering ambient light according to claim 3, wherein the analog-to-digital converter is based on the number of sampling information and the pulse number information stored in the register to convert the first environment The light signal is converted into the first data, and the second ambient light signal and the reflected signal are converted based on the sampling frequency information and the pulse wave number information stored in the register Is the second data, and based on the sampling frequency information stored in the register And the pulse wave number information, and convert the third ambient light signal into the third data. The method for filtering ambient light according to claim 1, wherein the sensing module is a proximity sensor. The method for filtering ambient light according to claim 1, wherein the emitter is a light emitting diode. The method for filtering ambient light according to claim 1, wherein the receiver is a photodiode. A method for filtering ambient light, comprising: providing a sensing module, the sensing module including a transmitter, a receiver, and a processor; performing a first sampling, the transmitter does not transmit a signal, The receiver receives a first ambient light signal, and the processor converts the first ambient light signal into a first data; performs a second sampling, the transmitter transmits a detection signal, and the receiver The device receives a second ambient light signal and the detection signal, and the processor converts the second ambient light signal and the detection signal into a second data; performs a third sampling, the transmitter Without transmitting a signal, the receiver receives a third ambient light signal, and the processor converts the third ambient light signal into a third data; performing a fourth sampling, the transmitter does not transmit a signal, so The receiver receives a fourth ambient light signal, and the processor converts the fourth ambient light signal into a fourth data; performs a fifth sampling, the transmitter transmits the detection signal, and the receiver The device receives a fifth ambient light signal and the detection signal, and the processor converts the fifth ambient light signal and the detection signal into a fifth data; calculates the first data and the first data Averaging three data and the fifth data to obtain a first average value; Calculating the average of the second data and the fourth data to obtain a second average; and calculating the difference between the second average and the first average to obtain a difference. The ambient light filtering method according to claim 8, wherein the first sampling, the second sampling, the third sampling, the fourth sampling, and the fifth sampling are completed in one sampling carried out. The method for filtering ambient light according to claim 8, wherein the first sampling, the second sampling, the third sampling, the fourth sampling, and the fifth sampling are performed in the sensing Execute within the distance range from the module to the object under test.

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