KR20120103860A - Sensor module for the optical measurement of distance - Google Patents

Abstract

PURPOSE: An optical sensor module for measuring a distance is provided to improve the measuring accuracy regardless of the distance from an object. CONSTITUTION: An optical sensor module(100) for measuring a distance comprises a light emitting part and a light receiving part. The light emitting part comprises a light source(20). The light source emits lights to objects. The light receiving part comprises lenses and a linear image sensor. The lenses collect the light reflected form the objects. The focal points of the lenses are changed according to the distance from the objects. Light-electricity conversion elements are placed in the linear image sensor.

Description

Optical distance measuring sensor module {SENSOR MODULE FOR THE OPTICAL MEASUREMENT OF DISTANCE}

The present invention relates to a distance measuring apparatus, and more particularly, to an optical distance measuring sensor module capable of measuring a distance from a detection target according to a focused position of light reflected from a detection target.

Distance measurement with a sensing target is required in various fields such as camera auto focus, wafer position detection in semiconductor manufacturing processes, vehicle distance measurement in automobiles, and robots for cleaning, and the range of application thereof has recently increased. For such distance measurement, a measuring method using ultrasonic waves, a measuring method using light, and the like are known.

As an example of a measurement technique using light, Korean Patent Publication No. 2009-0039208 discloses a distance measuring sensor module using a position sensitive device (PSD). Specifically, the sensor module includes a light emitting unit and a light receiving unit, wherein the light emitting unit includes an infrared LED for emitting infrared rays to an object for distance measurement and a light emitting unit lens for forming infrared rays as parallel light, and the light receiving unit is formed from an object. It consists of a light receiving unit lens for condensing the reflected infrared rays and a position detecting element for measuring the distance to the object through the collected infrared rays. The document describes the arrangement of the light emitting portion and the light receiving portion so that the optical axis of the infrared rays emitted from the light emitting portion and the optical axis of the infrared light collected by the light receiving portion maintain a constant angle in order to improve the accuracy of the distance measurement.

In the conventional distance measuring method using a position detecting device, which is a semiconductor device that detects a short-distance position of incident light by using a single pn junction by using a surface resistance of a semiconductor, a resistance between channels differs depending on the position due to a barrier generated by light. It's a way of using properties that represent values. This method is easy and accurate to detect the position of the light incident angle, but it is difficult to make the device, there is a problem that the accuracy is reduced because several barriers are generated in noise and strong light. In addition, a separate additional circuit for measuring resistance and current is needed.

On the other hand, conventional measurement methods have a problem that the measured value varies depending on the degree of reflection of the detection object.

The present invention has been made to solve the above-described problems of the prior art, to provide an optical distance measuring sensor module capable of precise distance measurement irrespective of the amount of light reflected from a detection object.

Another object of the present invention is to provide an optical distance measuring sensor module having an increased measuring distance range.

The sensor module for measuring the distance of the detection object according to the present invention is basically a light emitting unit including a light source for emitting light toward the detection object and a light receiving unit for receiving the light reflected by the detection object to convert light energy into electrical energy It includes. The light emitting unit and the light receiving unit may be mounted on a single substrate at a predetermined distance, and the light emitting unit and the light receiving unit may be located in a case capable of shielding external light. It is preferable that a partition wall is provided between the light emitting portion and the light receiving portion to block the influence of each other.

According to the invention, the light source of the light emitting portion is preferably a light emitting diode (LED) emitting infrared light. In order to concentrate the light from the light source, the light emitting unit may include a condenser lens disposed at a predetermined distance from the light source. The condensing lens is preferably a lens having a refractive index for inducing light emitted from the light source into substantially parallel light.

The light receiving unit of the distance measuring sensor module collects the light reflected by the object to be detected and changes the focus position according to the reflected light according to the distance of the object to be detected, and receives the light collected through the lens and converts the light into electrical energy. A plurality of photo-electric conversion elements include linear image sensors LIS arranged in a row. The light receiving unit may include an analog-to-digital converter (AD converter) for converting the output of the photo-electric conversion elements into a digital signal.

The present invention is a distance from the object to be detected based on the amount of electrical energy generated in each of the photo-electric conversion elements receiving the focused light of the plurality of photo-electric conversion elements arranged in a line of the linear image sensor Characterized in determining. The distance from the object to be detected can be determined by mathematically converting the output of each photo-electric conversion element. According to the present invention, a more accurate distance calculation is possible by estimating using the variance of the normal distribution. For example, the output values of the plurality of photo-electric conversion elements may be output in the form of a normal distribution, and the position of the photo-electric conversion element representing the maximum output may be determined by calculating an average median of the output normal distribution values. Thereby, by determining the position of the photo-electric conversion element of maximum output, the distance with the detection object corresponding to the position can be calculated. The process for calculating this distance is preferably carried out by a microcontroller (MCU).

In the present invention, it is preferable that the light-receiving portion lens is an aspheric lens so that the position of the reflected light collected by the light-receiving portion lens in the linear image sensor can be changed depending on the distance from the detection object. In addition, the light receiving unit lens is preferably mounted so that the position, tilt and the like of the lens can be adjusted. Thereby, by changing the position reflected by the detection object and condensed by the linear image sensor, it is possible to adjust to the measurement distance range short distance, medium distance, long distance, etc. of a detection object.

In the plurality of photo-electric conversion elements arranged in a line in the linear image sensor, individual photo-electric conversion elements may be arranged in contact with each other or arranged at a predetermined interval. The photo-electric conversion elements arranged in the linear image sensor are not limited to the number of at least 2, at least 10, at least 100, at least 1000, etc., but as the number thereof increases, the distance measuring range and the measuring distance accuracy are generally It will increase. The photo-electric conversion element is preferably elongated shape so that the number included per unit area of the linear image sensor can be increased. As will be appreciated by those skilled in the art, the photo-electric converter is a device capable of converting light energy into electrical energy. The photo-electric conversion device is preferably a complementary metal oxide semiconductor (CMOS) or a charge coupled device (CCD), but is not limited thereto. The photo-electric conversion element may include a photoelectric conversion semiconductor such as a photodiode, a phototransistor, and the like, in which an output current increases in proportion to the amount of light, and an element for converting the output current thereof into a voltage.

In the present invention, as the distance between the distance sensor module and the object to be detected changes, the position of the light spot collected by the light receiving unit lens and incident on the light receiving surface of the linear image sensor of the light receiving unit is changed. For example, as the distance from the detection object increases, the light reflected from the detection object may be designed to be focused toward the photo-electric conversion element closer to the light emitting part of the plurality of photo-electric conversion elements. As a result, the position of the photo-electric conversion element that generates relatively high electrical energy changes, and the position of the photo-electric conversion element exhibiting the high electrical energy (that is, the number of photo-electric conversion elements exhibits the maximum output power). Therefore, the distance with the detection object can be measured based on the distance conversion value for the predetermined maximum output photo-electric conversion element.

According to the present invention, since the output difference is very large between the photo-electric conversion elements receiving the collected reflected light and the photo-electric conversion elements not receiving the reflected light, the distance is accurately calculated without the influence of the ambient light due to the presence of noise, the intensity of the reflected light, and the like. can do.

The size of the light spot incident on the light receiving surface of the linear image sensor may be adjusted in consideration of the size of each photo-electric conversion element of the linear image sensor. For example, the size of the light spot may be adjusted by changing the distance between the light receiving unit lens and the linear image sensor or by changing the refractive index of the light receiving unit lens. The width of the light spot is preferably set to be wider than the width of the light receiving surface of each photo-electric conversion element. This allows the plurality of opto-electric conversion elements to receive the spot of reflected light, thereby calculating the mean median of the normal distribution values output by the plurality of the opto-electric conversion elements, thereby increasing the reliability of the output data of the linear image sensor. Can be. If the width of the light spot is narrower than the width of the light receiving surface of each photo-electric conversion element, the output by the reflected light will appear only in one photo-electric conversion element, and thus calculation by the normal distribution of the output values becomes difficult. Precise distance conversion can be difficult.

According to one aspect of the invention, the linear image sensor may be arranged in a plurality of rows up and down. In this case, the accuracy of the distance measurement with the detection object can be improved, and the coordinate can be measured by calculating the degree of deflection by detecting the spot of the reflected light moving up and down.

The present invention provides a new type of distance measuring sensor module using a linear image sensor. The distance measuring sensor module according to the present invention can improve the accuracy of distance measurement regardless of the distance or reflectance of the object to be detected. In addition, the distance measuring sensor module of the present invention enables a very wide range of distance measurement.

1 is a view schematically showing a distance measuring module and a distance measuring method according to an embodiment of the present invention.
2 is a view showing the arrangement of the light source and the linear sensor array in the distance measuring sensor module according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating a position in which a light reflected by a detection object is focused as the distance of the detection object is changed in the linear sensor array according to an exemplary embodiment of the present invention.
4 to 6 are graphs showing actual output values of respective photo-voltage conversion elements of the linear sensor array according to the embodiment of the present invention as the distance from the detection object is changed.
7 is a graph showing the relationship between the position of the photo-voltage conversion element showing the maximum output and the distance of the detection object in the linear sensor array according to the embodiment of the present invention.

Additional aspects, features, and advantages of the invention include the following description of representative embodiments, which description should be understood in conjunction with the accompanying drawings. In order to facilitate a clear understanding of the present invention, some elements in each drawing may be exaggerated, omitted, or schematically illustrated. In addition, the size of each component does not entirely reflect the actual size. The following examples are intended to illustrate preferred embodiments of the present invention in order to enable those skilled in the art to understand and to facilitate the present invention, and should not be construed as limiting the present invention. Those skilled in the art will recognize that various changes and modifications can be made within the spirit and scope of the invention.

First, referring to FIG. 1, the distance measuring sensor module 100 according to the present invention includes a light emitting part including a light source 20 and a lens 30, and a light receiving part including a linear sensor array 40 and a lens 50. It consists of. The light source 20 and the linear sensor array 40 are provided to be mounted on the printed circuit board 10 at predetermined intervals. The light emitting unit and the light receiving unit are shielded by the cover 60 to prevent light transmission and disturbance light. Slits are formed in each of the light emitting area and the light receiving area, and the light emitting part lens 30 and the light receiving part lens 50 are mounted on the slits.

The light emitted from the light source 20 is collected by the light emitter lens 30 and proceeds toward the detection objects 71, 72, and 73. The light reflected by the detection targets 71, 72, 73 is concentrated through the lens 50 of the light receiver and is incident on the linear sensor array 40.

According to the present invention, the light receiving part lens 50 is configured such that light incident on the sensor array 40 moves toward the side closer to the light source 20 in the sensor array 40 as the distance of the object to be detected increases. As shown in FIG. 1, the light reflected by the detection object 71 located at a relatively close position is focused on the right side in the sensor array 40 through the light receiving unit lens 50, and is located farther than the detection object 71. The light reflected by the detection object 72 is focused centrally within the sensor array 40 through the light receiving unit lens 50, and the light reflected by the farthest detection object 73 is located farthest from the light receiving unit lens 50. Through the sensor array 40 is concentrated on the left side.

2 is a more detailed view of the linear sensor array 40 in the distance measuring sensor module according to the present invention. The sensor array 40 has a shape in which about 150 photo-voltage conversion elements are arranged in series with each other. As an aspect of the present invention, the sensor array 40 is a CMOS linear sensor array in which unit cells are arranged in a row.

Each photo-voltage conversion element of the sensor array 40 is arranged such that the light receiving surface faces the lens 50, and each light receiving surface is formed to be substantially elongated. A reference drive voltage is applied to each photo-voltage conversion element, and each photo-voltage conversion element converts light incident on its light receiving surface into a voltage proportional to the amount of light. One side of the light receiving portion is provided with a plurality of data lines 201-209 for transmitting signals from each photo-voltage conversion element of the linear sensor array 40. The data lines 201-209 transmit a signal from the photo-voltage conversion element to, for example, a microcontroller (MCU), and the MCU calculates an output value of the photo-voltage conversion element to convert the distance.

3 shows that the light receiving surface of the sensor array 40 which receives the light reflected by the detection object moves as the distance of the detection object changes. Referring to FIG. 1, the light reflected by the detection object 71 passes through the light receiving unit lens 50 and is focused on a plurality of light-voltage conversion elements 301 neighboring each other in the sensor array 40. The number of light-voltage conversion elements 301 that receive the reflected light of the detection object 71 may be determined by adjusting the spot size of the light focused on the light receiving surface, the size and spacing of the individual light-voltage conversion elements, and the like. . Similarly, the light reflected by the detection object 72 passes through the light-receiving portion lens 50 and is then focused on a plurality of light-to-voltage conversion elements 302 neighboring each other in the sensor array 40, and the detection object 73 The light reflected by) is focused on a plurality of photo-voltage conversion elements 301 neighboring each other. Therefore, as the distance of the object to be detected increases, the reflected light focused on the sensor array 40 moves toward the nearer side from the far side of the light source 20.

4 to 6 show the relationship between the distance for each object to be detected and the voltage output values of the photo-voltage conversion elements. Referring to FIG. 3, the light-receiving surface of the collected reflected light among the photo-voltage conversion elements 301 of the sensor array 40 is formed at the photo-voltage conversion element (about 110th photo-voltage conversion element from the left) located at the center. It is the widest and decreases in area toward the periphery. Therefore, the output of the photo-voltage conversion element located at the center of the photo-voltage conversion elements 301 is the largest, the output of the photo-voltage conversion element immediately adjacent to the left and right thereof is next, and the output increases as the distance from the left and right gradually increases. This will decrease gradually. This output is shown in the form of a normal distribution curve as shown in FIG. That is, in the 110th photo-voltage conversion element, the output is the largest and parabolic in which the output decreases gradually from side to side. Ripples with relatively large amplitudes exist on the left and right sides of the parabola, which is a phenomenon in which the intensity of the reflected light is high because the detection target 71 is close to each other. However, since the output difference between the photo-voltage conversion elements 301 which receive the collected reflected light and the photo-voltage conversion elements which are not received is very large, the photo-voltage conversion showing the peak value in the sensor array 40 even if these ripples exist. The distance of the object to be detected can be calculated by accurately grasping the device by calculating the median of the normal distribution of the output values of the photo-voltage conversion device. When the position of the photo-voltage conversion element showing the maximum output value is known, for example, as shown in FIG. 7, the object to be detected is in accordance with the distance conversion relationship with the detection object according to the position of the photo-voltage conversion element showing the maximum output. Find out the distance.

5 and 6 show output values of respective light-voltage conversion elements of the sensor array 40 when the light reflected by the detection object 72 and the detection object 73 is collected through the light receiving unit lens 50, respectively. Indicates. Referring to FIG. 5, the photo-voltage conversion element representing the maximum output value has moved to the left side from about 110 th to about 75 th compared to FIG. 4. As in FIG. 4, the output value is parabolic in the photo-voltage conversion elements that receive the collected reflected light, but the output value is relatively small in the photo-voltage conversion elements that do not receive the reflected light. As the distance of the object to be detected decreases, the intensity of the reflected light is weakened, so that the amplitude of the ripple existing on the left and right sides of the parabola is also relatively small compared to FIG. 4. In FIG. 7, as the distance of the object to be detected increases, the photo-voltage conversion element showing the peak value moves to the 40th position, and the amplitude of the ripple decreases as the intensity of the reflected light decreases.

4 to 6, the maximum output value is shown to be similar in each drawing even when the distance of the object to be detected increases. The reason is that even when the intensity of the reflected light decreases as the distance of the object to be detected decreases, the influence of the disturbance light increases, and the output value of the disturbance light and the output value of the reflected light are added to affect the maximum output value. However, the position of the light-to-voltage conversion element representing the maximum output value can be determined based on the average median expressed as a normal distribution of the output values of the light-to-voltage conversion elements, thereby converting the distance of the object to be detected. The magnitude of the maximum output value of the electrical conversion element does not affect the distance measurement.

Although the invention has been described in terms of representative embodiments, it should be understood that the invention has the right to be protected in all its scope as set forth in the claims.

100: distance measuring sensor module 10: substrate 20: light source
30 light emitting part lens 40 linear sensor array 50 light receiving part lens
60: cover 71, 72, 73: detection object

Claims (11)

A sensor module for measuring the distance of the object to be detected,
A light emitting unit including a light source for emitting light toward a detection object; And
A lens for condensing the light reflected by the object to be detected, the position of the focus being changed according to the reflected light according to the distance of the object to be detected; And a linear image sensor in which a plurality of photo-electric conversion elements for receiving light collected through the lens and converting the light collected through the lens into electrical energy are arranged in a row.
Including;
Determining the distance to the detection object based on the amount of electrical energy generated in each of the photo-electric conversion elements receiving the focused light among the plurality of photo-electric conversion elements arranged in a row of the linear image sensor. Distance measuring sensor module. The distance measuring module according to claim 1, wherein the width of the light spot incident on the light receiving surface of the linear image sensor is wider than the width of the light receiving surface of the individual photo-electric conversion elements of the linear image sensor. The light reflected from the detection object is focused toward the photo-electric conversion element closer to the light emitting part of the plurality of photo-electric conversion elements as the distance from the detection object increases. Distance measuring sensor module. 3. The distance measuring module according to claim 1 or 2, wherein the light source is an infrared LED. The distance measuring module of claim 4, wherein the light emitting unit further comprises a lens for condensing light emitted from the light source. 3. The distance measuring module according to claim 1 or 2, wherein the photo-electric conversion element comprises a CMOS, a CCD, a photodiode, or a phototransistor. 3. The distance measuring module according to claim 1 or 2, wherein the lens of the light receiving portion is arranged such that its tilt or distance from the linear image sensor is adjustable. The optical-electric conversion device of claim 1, wherein an average median value of the normal distribution values of the outputs of the plurality of optical-electric conversion devices is calculated to determine the photo-electric conversion device representing the maximum output, and based on the detection object, according to the present invention. A distance measuring sensor module further comprising a microcontroller for calculating a distance. The distance measuring sensor module according to claim 1 or 2, comprising a plurality of linear image sensors. A distance sensor module package equipped with a sensor for measuring the distance of an object,
Board;
A cover surrounding the substrate;
An infrared light emitting device mounted on the substrate;
A light emitting side lens mounted on the cover and configured to collect infrared light emitted from the infrared light emitting device;
A light receiving side lens mounted on the cover and configured to collect light reflected by an object and to change a focus position according to an incident angle of the reflected light; And
A linear sensor array mounted on the substrate at a predetermined distance from the infrared light emitting device, the light receiving surface being formed by a plurality of series of photo-voltage conversion elements arranged in series;
Distance measurement sensor module package comprising a. 11. The distance sensor module package of claim 10, wherein the individual photo-to-voltage conversion elements of the linear sensor array are arranged in series with each other in contact or spaced apart.

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