KR20170047424A - Optical proximity sensor reducing the effect of ambient light - Google Patents

Optical proximity sensor reducing the effect of ambient light Download PDF

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Publication number
KR20170047424A
KR20170047424A KR1020150147055A KR20150147055A KR20170047424A KR 20170047424 A KR20170047424 A KR 20170047424A KR 1020150147055 A KR1020150147055 A KR 1020150147055A KR 20150147055 A KR20150147055 A KR 20150147055A KR 20170047424 A KR20170047424 A KR 20170047424A
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KR
South Korea
Prior art keywords
current
offset control
detection
control signal
proximity sensor
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KR1020150147055A
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Korean (ko)
Inventor
최정열
정우주
이원우
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주식회사 센소니아
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Priority to KR1020150147055A priority Critical patent/KR20170047424A/en
Publication of KR20170047424A publication Critical patent/KR20170047424A/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V8/00—Prospecting or detecting by optical means
    • G01V8/10—Detecting, e.g. by using light barriers
    • G01V8/12—Detecting, e.g. by using light barriers using one transmitter and one receiver
    • G01V8/14—Detecting, e.g. by using light barriers using one transmitter and one receiver using reflectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V13/00—Manufacturing, calibrating, cleaning, or repairing instruments or devices covered by groups G01V1/00 – G01V11/00
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics (AREA)
  • Manufacturing & Machinery (AREA)
  • Power Engineering (AREA)
  • Electronic Switches (AREA)

Abstract

Disclosed is an optical proximity sensor for reducing an effect of ambient light. According to the present invention, the optical proximity sensor comprises: a light source enabled in a sensing operation to provide light; a light detector driven to generate a detection current indicating strength of received light to supply the detection current to a detection node; a detection light checker to generate checking data having a data value in accordance with the current supplied to the detection node; and an offset control generator to generate an offset control signal having a voltage level in accordance with the data value of the checking data in a preparatory operation. A voltage level of the offset control signal is controlled in a direction making a magnitude of a compensation current equal to a magnitude of the detection current in the preparatory operation. The offset control generator is latched when a difference between the magnitude of the compensation current and the magnitude of the detection current is within a prescribed range. The optical proximity sensor further comprises a compensation driver driven to supply the compensation current to the light detector through the detection node. The compensation current follows a voltage level of a latched offset control signal in the sensing operation. According to the optical proximity sensor, an effect of ambient light is reduced to improve accuracy of proximity sensing.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical proximity sensor for reducing the influence of ambient light,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical proximity sensor, and more particularly, to an optical proximity sensor that reduces the influence of ambient light and improves operational characteristics.

In general, a sensor that detects the proximity of an object in a noncontact manner is referred to as a proximity sensor. In particular, a proximity sensor using light such as infrared rays is referred to as an optical proximity sensor do.

1 is a view showing a conventional optical proximity sensor. The conventional optical proximity sensor includes a light source 10, a photodiode 20, and a detection light verifier 30 that generate light. At this time, the photodiode 20 generates a detection current IDT according to the intensity of the received light, and the photodetector 20 generates the detection current IDT according to the amount of the detection current IDT generated by the photodiode 20 And generates verification data (DAMT) of the digital component as the voltage level of the detection node (NDEC). This optical proximity sensor is driven to ascertain the proximity of the object OBJ via the magnitude of the identification data DAMT.

On the other hand, the optical proximity sensor occasionally occasionally closes the object (OBJ) in an environment where ambient light such as sunlight or fluorescent light is present.

1, the detection current IDT is not only the target current IBJ generated in the reflected light generated by the light of the light source OBJ reflected by the object OBJ, And the ambient current (ISN) generated by the same ambient light. Further, in the environment where the sunlight is strong, the peripheral current ISN becomes much larger than the target current IBJ.

In this case, the specific current of the object current IBJ may be substantially reduced or the photodiode 20 may operate in a saturation region.

As a result, the optical proximity sensor of Fig. 1 has a problem in that the accuracy of proximity sensing of the object OBJ through the confirmation data DAMT is lowered.

It is an object of the present invention to provide an optical proximity sensor for reducing the influence of ambient light and improving the accuracy of proximity sensing of an object.

According to an aspect of the present invention, there is provided an optical proximity sensor. The optical proximity sensor of the present invention includes a light source enabled in a sensing operation to provide light; A photodetector driven to generate and provide a detection current indicative of the intensity of the received light to the detection node; A detection light verifier generating verification data having a data value according to a current provided to the detection node; An offset control signal for generating an offset control signal having a voltage level corresponding to a data value of the confirmation data in a preliminary operation, wherein the offset control signal is generated in a direction in which the magnitude of the compensation current in the preliminary operation becomes equal to the magnitude of the detection current Wherein the voltage level is controlled and the offset control generator is latched when the difference between the magnitude of the compensation current and the magnitude of the detection current is within a certain range; And a compensation driver driven to provide the compensation current to the photodetector via the detection node, wherein the compensation current comprises the compensation driver according to the voltage level of the offset control signal latched in the sensing operation.

In the optical proximity sensor of the present invention configured as described above, an offset effect according to ambient light such as sunlight is detected in the preliminary operation, and the proximity of the object is detected by removing the offset effect detected in the preliminary operation in the sensing operation. Accordingly, according to the optical proximity sensor of the present invention, the influence of the ambient light is reduced, and the accuracy of proximity sensing of the object is improved.

A brief description of each drawing used in the present invention is provided.
1 is a view showing a conventional optical proximity sensor.
2 is a view of an optical proximity sensor according to an embodiment of the present invention.
FIGS. 3 and 4 are views for explaining the preliminary operation and the sensing operation of the optical proximity sensor of FIG. 2, respectively.

For a better understanding of the present invention and its operational advantages, and the objects attained by the practice of the present invention, reference should be made to the accompanying drawings, which illustrate preferred embodiments of the invention, and the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are being provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

It should be noted that, in understanding each of the drawings, the same members are denoted by the same reference numerals whenever possible.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a view of an optical proximity sensor according to an embodiment of the present invention. At this time, the optical proximity sensor of the present invention performs the sensing operation (OP-SEN, see Fig. 4) after performing the preliminary operation (OP-PRE, The proximity of the object.

That is, in the preliminary operation (OP-PRE), an offset effect according to ambient light such as sunlight is detected. In the sensing operation (OP-SEN), the proximity of the object is detected by reflecting the offset effect grasped in the preliminary operation (OP-PRE) in the direction of eliminating the offset effect.

Referring to FIG. 2, the optical proximity sensor of the present invention includes a light source 100, a photodetector 200, and a detection light identifier 300.

The light source 100 provides light in a sensing operation (OP-SEN). The light source 100 specifically includes an optical switch 110 and a light source unit 120. The optical switch 110 is turned off in response to deactivation of the spare mode signal XMPR. The light source unit 120 provides the light by the current received through the optical switch 110.

In the present embodiment, the spare mode signal XMPR is activated in the preliminary operation OP-PRE and deactivated in the sensing operation OP-SEN. Accordingly, the light source 100 is disabled in the pre-operation (OP-PRE) and does not provide light, and is enabled in the sensing operation (OP-SEN) to provide light.

The light source unit 120 may be, for example, one or more light emitting diodes (LEDs) or laser diodes, but is not limited thereto. In addition, the light source unit 120 may provide infrared (IR) light or light of a different wavelength.

The photodetector 200 is driven to generate a detection current IDT indicative of the intensity of the received light and provide it to the detection node NDEC. The photodetector 200 may be, for example, one or more photodiodes (PD) for generating the detection current IDT according to the intensity of incident light. However, it is noted that the photodetector 200 may additionally include, but is not limited to, analog signal processing and / or buffer circuits.

The detection light verifier 300 generates confirmation data (DAMT) having a data value according to the current supplied to the detection node NDEC. Preferably, the confirmation data (DAMT) has a data value of a digital component.

The detection light verifier 300 specifically includes a voltage integrating unit 310 and an analog-to-digital conversion unit 330.

The voltage integrating means 310 integrates a voltage according to the current of the detection node NDEC to generate an analog confirmation signal VANMT.

More specifically, the voltage integrating means 310 includes a driving amplifier 311, a reset switch 313, and a feedback capacitor 315.

The driving amplifier 311 inverts and amplifies the voltage of the detection node NDEC. The reset switch 313 electrically connects the output of the drive amplifier 311 to the detection node NDEC in response to a switch reset signal RSTS. At this time, both the output of the driving amplifier 311 and the detection node NDEC are controlled to the reference voltage VREF.

The feedback capacitor 315 negatively couples the detection node NDEC to the output of the driving amplifier 311.

According to the voltage integrating means 310, the voltage corresponding to the current of the detection node NDEC is integrated and generated as the analog confirmation signal VANMT.

The analog-to-digital conversion means 330 is generated by converting the analog confirmation signal VANMT into the confirmation data DAMT of a digital component (e.g., N-bit).

On the other hand, when the intensity of the ambient light such as sunlight is large, it is difficult to detect the proximity of the object. Further, when the intensity of the ambient light such as sunlight is equal to or greater than a threshold value, the driving amplifier 200 operates in a saturation region. As a result, the optical proximity sensor malfunctions due to the offset effect of ambient light.

In the optical proximity sensor of the present invention, a compensation current (ICMP) is provided to the detection node (NDEC) in order to eliminate the offset effect of ambient light.

To this end, the optical proximity sensor of the present invention further comprises an offset control generator 400 and a compensation driver 500.

The offset control generator 400 generates an offset control signal XCFS. At this time, the offset control signal XCFS is generated when the data value of the confirmation data DAMT is in the pre-operation OP-PRE but the confirmation data DAMT has a data value within the reference range Is latched.

That is, the offset control signal XCFS is set so that the magnitude of the compensation current ICMP provided from the compensation driver 500 in the pre-operation OP-PRE becomes equal to the magnitude of the detection current IDT The voltage level is controlled. When the difference between the magnitude of the compensation current ICMP and the magnitude of the detection current IDT is within a predetermined range in the preliminary operation OP-PRE, the offset control signal XCFS is preferably set to the compensation And is latched when the magnitude of the current ICMP and the magnitude of the detection current IDT become equal.

In the sensing operation OP-SEN, the offset control signal XCFS remains latched in the pre-operation OP-PRE.

The offset control generator 400 specifically includes an offset switch 410 and an offset control signal generator 430.

The offset switch 410 is turned on in response to activation of the spare mode signal XMPR. That is, the offset switch 410 is turned on at the pre-operation OP-PRE and turned off at the sensing operation OP-SEN.

The offset control signal generating means 430 generates the offset control signal XCFS using the confirmation data DAMT provided through the offset switch 410 in the preliminary operation OP- do.

At this time, the offset control signal generating means 430 generates a latch signal for latching the offset control signal XCFS when the confirmation data DAMT has a data value within the reference range in the pre-operation OP- Unit 431 as shown in Fig.

That is, when the difference between the magnitude of the compensation current ICMP and the magnitude of the detection current IDT in the pre-operation OP-PRE is within a predetermined range, the offset control signal generating means 430 generates the offset control signal (XCFS).

The latch unit 431 releases the latch of the offset control signal XCFS in response to the latch reset signal RSTL activated in the preliminary operation OP-PRE. That is, the offset control signal XCFS is initialized (for example, a voltage of '0V') when the latch reset signal RSTL is activated in the pre-operation OP-PRE.

The compensation driver 500 is driven to provide a compensation current ICMP to the detection node NDEC. At this time, the magnitude of the compensation current ICMP depends on the voltage level of the offset control signal XCFS.

Continuing to refer to FIG. 2, the optical proximity sensor of the present invention further comprises an output switch 600.

The output switch 600 is turned on in the sensing operation OP-SEN in which the preliminary mode signal XMPR is inactivated and transmits the confirmation data DAMT to the outside.

Subsequently, driving of the optical proximity sensor of the present invention is summarized.

Figs. 3 and 4 are diagrams for explaining the preliminary operation (OP-PRE) and the sensing operation (OP-SEN) of the optical proximity sensor of Fig. 2, respectively.

First, in the pre-operation (OP-PRE) of FIG. 3, the light source 100 is disabled, and the offset switch 410 is turned on.

At this time, the magnitude of the detection current IDT generated by the photodetector 200 corresponds to the peripheral current ISN according to the ambient light such as sunlight, excluding the reflected light reflected by the object OBJ.

The compensation driver 500 provides the compensation current ICMP according to the voltage level of the offset control signal XCFS to the photodetector 200 through the detection node NDEC.

Accordingly, the net current amount provided to the detection node NDEC becomes a value obtained by subtracting the compensation current ICMP from the detection current IDT.

The net current amount provided to the detection node NDEC is reflected in the confirmation data DAMT and the offset control signal generating means 430 generates a voltage level dependent on the data value of the confirmation data DAMT Generates the offset control signal XCFS.

At this time, the offset control signal generating means 430 controls the voltage level of the offset control signal XCFS in a direction in which the compensation current ICMP becomes equal to the detection current IDT.

The latch unit 431 of the offset control signal generating means 430 latches the voltage level of the offset control signal XCFS when the confirmation data DAMT has a data value within the reference range .

In other words, the voltage level of the offset control signal XCFS is latched when the compensation current ICMP becomes equal to the detection current IDT, i.e., the peripheral current ISN.

4, the light source 100 is enabled to provide light, and the offset switch 410 is turned off.

At this time, the magnitude of the detection current IDT generated by the photodetector 200 depends on the target current IBJ generated in the reflection light generated by the light of the light source OBJ reflected on the object OBJ, , And ambient currents (ISN) generated by ambient light such as sunlight.

The compensation driver 500 provides the compensation current ICMP having the same value as the ambient current ISN to the photodetector 200 through the detection node NDEC.

Accordingly, the net current amount provided to the detection node NDEC becomes a value obtained by subtracting the compensation current ICMP from the detection current IDT, that is, the target current IBJ.

In summary, in the optical proximity sensor of the present invention, the data value of the confirmation data DAMT generated by the detection light verifier 300 reflects only the subject current IBJ excluding the peripheral current ISN.

That is, in the optical proximity sensor of the present invention, an offset effect according to ambient light such as sunlight is detected in the preliminary operation, and the proximity of the object is detected by removing the offset effect detected in the preliminary operation in the sensing operation.

As a result, according to the optical proximity sensor of the present invention, the influence of the ambient light is reduced, and the accuracy of proximity sensing of the object is improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (7)

In an optical proximity sensor,
A light source enabled in the sensing operation to provide light;
A photodetector driven to generate and provide a detection current indicative of the intensity of the received light to the detection node;
A detection light verifier generating verification data having a data value according to a current provided to the detection node;
An offset control signal for generating an offset control signal having a voltage level corresponding to a data value of the confirmation data in a preliminary operation, wherein the offset control signal is generated in a direction in which the magnitude of the compensation current in the preliminary operation becomes equal to the magnitude of the detection current Wherein the voltage level is controlled and the offset control generator is latched when the difference between the magnitude of the compensation current and the magnitude of the detection current is within a certain range; And
A compensating driver driven to provide the compensating current to the photodetector via the detecting node, wherein the compensation current comprises the compensating driver in accordance with the voltage level of the latched offset control signal in the sensing operation Proximity sensor.
The light source according to claim 1,
And wherein the optical proximity sensor is disabled in the preliminary operation.
The apparatus according to claim 1, wherein the detection light identifier
Voltage accumulation means for accumulating voltages according to the current of the detection node and generating as an analog confirmation signal; And
And analog-to-digital conversion means for generating the analog confirmation signal as the confirmation data of the digital component.
2. The apparatus of claim 1, wherein the offset control generator
An offset switch that is turned on in the preliminary operation and transmits the offset data; And
And offset control signal generating means for generating the offset control signal using the confirmation data provided through the offset switch in the preliminary operation.
5. The apparatus of claim 4, wherein the offset control signal generating means
And a latch unit for latching the offset control signal when the difference between the magnitude of the compensation current and the magnitude of the detection current is within a predetermined range in the preliminary operation.
6. The apparatus of claim 5, wherein the latch unit
Responsive to a latch reset signal activated in the preliminary operation, releases the latch of the voltage level of the offset control signal.
The optical proximity sensor according to claim 1, wherein the optical proximity sensor
And an output switch for transmitting the confirmation data to the outside in the sensing operation.
KR1020150147055A 2015-10-22 2015-10-22 Optical proximity sensor reducing the effect of ambient light KR20170047424A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111948725A (en) * 2019-05-17 2020-11-17 敦宏科技股份有限公司 Optical proximity sensing device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111948725A (en) * 2019-05-17 2020-11-17 敦宏科技股份有限公司 Optical proximity sensing device

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