JP2012063217A - Passive type optical range finding sensor, electronic apparatus and range finding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a passive optical range finding sensor capable of detecting existence of a human body, detecting a distance up to the human body and suppressing power consumption in a compact shape, and to provide an electronic apparatus and a range finding method.SOLUTION: Position detection elements 1, 2 having light receiving sensitivity in a far-infrared region are used for the passive type optical range finding sensor. Thus the human body detecting passive type optical range finding sensor is capable of saving power without including a light emitting element and its driving circuit, and a range finding method for the sensor can be achieved.

Description

  The present invention relates to a passive optical distance measuring sensor that measures the distance to an object to be measured by receiving light emitted from the object to be measured, and an electronic apparatus including the passive optical distance measuring sensor. The present invention also relates to a distance measuring method for measuring a distance to a measured object using light emitted from the measured object.

  Conventionally, as an optical distance measuring sensor, there is a hybrid type human body detecting sensor described in Japanese Patent Laid-Open No. 08-338880 (Patent Document 1). This human body detection sensor includes a pyroelectric sensor unit and an infrared distance measuring sensor unit.

  While the pyroelectric sensor unit does not detect a stationary object, it detects heat rays (far infrared rays) to recognize the presence of a human body, but cannot detect a distance to a detection target.

  On the other hand, the infrared-type distance measuring sensor unit emits near-infrared light from the light-emitting element and detects reflected light from the detected object by a triangulation method using a position detection element (PSD (Position Sensitive Detector) element). On the other hand, it is impossible to identify whether it is a human body.

  In the human body sensor, the pyroelectric sensor unit recognizes the presence of a human body, and the distance measuring sensor unit measures the distance to the object to be detected. In this way, the human body sensor is configured to detect the presence of the human body and the distance to the human body in a non-contact manner.

  This human body sensor has an advantage that it can detect the presence of the human body and can detect the distance to the human body without contact. However, this human body sensor requires a light receiving element of the pyroelectric sensor unit, a light emitting element of the infrared sensor unit, a light receiving element of the infrared sensor unit, and a circuit and a drive circuit for controlling each element. There is a problem that the sensor itself is enlarged and the mounting area of elements and wiring in the sensor is large. In addition, since many elements are driven, there is a problem that power consumption is large. That is, the conventional pyroelectric sensor + infrared distance measuring sensor hybrid type sensor that performs human body detection and distance measurement at the same time increases the outer shape of the sensor itself, so it is not only necessary to increase the mounting area, There is a problem that power consumption increases because the element is driven.

Japanese Patent Laid-Open No. 08-338880

  SUMMARY OF THE INVENTION An object of the present invention is to provide a passive optical distance measuring sensor that can detect the presence of a human body, detect the distance to the human body, and is compact and can suppress power consumption. Another object of the present invention is to provide a distance measuring method capable of detecting the presence of a human body and detecting the distance to the human body with a simple configuration and low cost.

In order to solve the above problems, the passive optical distance measuring sensor of the present invention is
A first position detecting element;
A first condenser lens disposed so as to focus on the light receiving surface of the first position detecting element;
The first position detection element has a light receiving sensitivity in a far infrared region,
The first position detection element receives a far infrared ray emitted from the object to be measured, thereby measuring the distance to the object to be detected.

  According to the present invention, since the position detecting element having the light receiving sensitivity is provided in the far infrared region, the distance measurement can be performed by directly receiving the far infrared ray emitted from the human body. Therefore, the sensor itself can be reduced in size. In addition, since a position detecting element having sensitivity to far infrared rays is used, it is possible to identify whether or not it is a human body.

In one embodiment,
The first position detection element is formed of an InSb-based semiconductor.

  By using InSb (band gap Eg = 0.17 eV) as the material of the position detection element, the peak spectral sensitivity λ can be set to about 7 μm (λ = 1.24 / Eg). Therefore, the wavelength of far-infrared rays from the human body is about 9 μm according to Wien's law (λmT = K λm: wavelength, T: absolute temperature, K = 2897.8), so use an InSb-based semiconductor. Thus, far infrared rays emitted from the human body can be received.

In one embodiment,
The first position detecting element can detect far infrared rays having a wavelength of about 9 μm.

  According to the embodiment, the first position detection element can detect a far infrared ray having a wavelength of about 9 μm, and thus can detect a person emitting a far infrared ray of about 9 μm. In addition, the first position detecting element can measure the distance to a person, and it is not necessary to provide a light emitting element used in the triangulation method, and a driving circuit for driving the light emitting element used in the triangulation method is provided. Since it is not necessary to prepare, a person can be detected with a much simpler configuration than before.

In one embodiment,
The peak spectral sensitivity of the first position detection element is 6 μm or more and 12 μm or less.

  According to the above embodiment, the peak spectral sensitivity of the first position detecting element is 6 μm or more and 12 μm or less, and therefore a person emitting a far infrared ray of about 9 μm can be accurately detected.

In one embodiment,
The first position detection element is formed of an InSb-based semiconductor,
A second position detection element formed of an InSb-based semiconductor;
A second condenser lens disposed so as to focus on the light receiving surface of the second position detecting element,
The light receiving surface of the first position detecting element and the light receiving surface of the second position detecting element are located on substantially the same plane.

  According to the above embodiment, since two position detection elements are used, it is possible to detect the direction in addition to the distance to the object to be measured.

  An electronic apparatus according to the present invention includes the passive optical distance measuring sensor according to the present invention.

Further, the distance measuring method of the present invention includes:
The light emitted from the object to be measured is received by the first position detecting element via the first condenser lens and received by the second position detecting element via the second condenser lens,
A focal position of light collected on a light receiving surface of each of the first position detecting element and the second position detecting element; a distance between the first position detecting element and the second position detecting element; A relative position of the second position detecting element with respect to one position detecting element, a relative position of the first collecting lens with respect to the first position detecting element, and a relative position of the second collecting lens with respect to the first position detecting element; Based on this, the distance to the object to be measured is measured.

  According to the present invention, measurement is performed based on the focal position of the light collected on the two position detection elements, the distance between the two position detection elements, and the positional relationship between the two position detection elements and the two lenses. Since the distance is provided, the distance and direction to the object to be measured can be accurately measured with a simple configuration.

In one embodiment,
Each of the first position detection element and the second position detection element has light receiving sensitivity to far infrared rays.

In one embodiment,
At least one of the first position detection element and the second position detection element receives at least one infrared ray and detects a person by detecting at least one of the first position detection element and the second position detection element. Yes.

The electronic device of the present invention is
It has a distance calculation part which calculates distance with the distance measuring method of the present invention.

  According to the passive optical distance measuring sensor of the present invention, since it has a position detection element having light receiving sensitivity in the far infrared region, it is possible to perform distance measurement by directly receiving far infrared rays emitted from the human body, The sensor itself can be reduced in size. In addition, it is possible to identify whether or not a human body with a position detection element having sensitivity to far infrared rays.

1 is a schematic cross-sectional view of a passive optical distance measuring sensor according to an embodiment of the present invention. It is a figure explaining the ranging method of one Embodiment of this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of a passive optical distance measuring sensor according to an embodiment of the present invention.

  As shown in FIG. 1, this passive optical distance measuring sensor has two integrated position detection elements (PSD) 1 and 2. Specifically, in this passive optical distance measuring sensor, the position detection elements 1 and 2 are die-bonded on the lead frames 5 and 6, and the position detection elements 1 and 2 are electrically connected to the lead frames 5 and 6. 6 is connected.

  Further, the case 10 in which the lens portions 8 and 9 are molded with translucent resin by two-color molding, while the other portion 12 such as a portion between the two position detection elements is molded with a light shielding resin, The lens portions 8 and 9 and the position detection elements 1 and 2 are integrated by being fixed to the lead frames 5 and 6. The lens unit 8 is disposed so as to focus on the light receiving surface of one position detecting element 1, and the lens unit 9 is disposed so as to focus on the light receiving surface of the other position detecting element 2. Yes.

  In the case 10, there is a control integrated circuit (IC) 13 mounted on the lead frame 7. The control integrated circuit 13 controls driving of the position detection elements 1 and 2 and the like. The passive optical distance sensor of this embodiment does not include a light emitting element used in the triangulation system and does not include a drive circuit that drives the light emitting element used in the triangulation system.

  In the present invention, the two position detection elements may be separated without packaging the two position detection elements with the same resin. Further, the lens unit may be retrofitted. The control circuit may be outside the resin case.

  FIG. 2 is a diagram illustrating a distance measuring method according to an embodiment of the present invention.

  This method uses a first position detection element 51, a second position detection element 52, a first condenser lens 53, and a second condenser lens 54. The first condenser lens 53 is disposed so as to be focused on the light receiving surface of the first position detecting element 51, and the second condenser lens 54 is focused on the light receiving surface of the second position detecting element 52. It is arranged to tie.

  As shown in FIG. 2, the first position detection element 51 and the second position detection element 52 are installed on the same plane, the light receiving surface 61 of the first position detection element 51, and the second position detection element 52. The light receiving surface 62 is located on substantially the same plane. The light receiving surface 61 of the first position detecting element 51 and the light receiving surface 62 of the second position detecting element 52 face the same direction.

  The first condenser lens 53 exists at a position where far infrared rays and the like radiated from an object to be measured such as a person can be condensed on the light receiving surface 61 of the first position detecting element 51, and the second condenser lens 54 The circular infrared ray emitted from the measurement object such as a person is present at a position where it can be condensed on the light receiving surface 62 of the second position detecting element 52. Further, the origin of the condensing point on the first position detecting element 51 is the center of the first condensing lens 53. The origin of the condensing point of the second position detecting element 52 is the center of the second condensing lens 54.

  Hereinafter, a method for measuring the distance and the direction when the object to be measured is present at the positions indicated by A, B, and C in FIG. 2 will be described.

  The position indicated by A in FIG. 2 is a case where, in the two-dimensional plane of FIG. 2, the object to be measured is on a vertical bisector of a straight line in which two position detection elements 1 and 2 are arranged. The first position detecting element 51 is positioned on a straight bisector of a straight line connecting the center of the light receiving surface 61 of the first position detecting element 51 and the center of the light receiving surface 62 of the second position detecting element 52.

  When the object to be measured is present at A, the first position detecting element 51 and the second position detecting element 52 receive light from the first position detecting element 51 and the second position detecting element 52. The light is condensed at a position equidistant from the intermediate line 70.

  Therefore, the distance l1 from the principle of triangulation to the object to be measured is l1: A = f: according to the position (x1, x2) from the origin (center of the condensing lenses 53, 54) on the position detection elements 51, 52. The relationship x1 = f: x2 is established. At this time, A is the distance from each lens to the intermediate line 70 between the lens 53 and the lens 54, and f is the distance from the first position detection element 51 to the first condenser lens 53, and the second position detection. This is the distance between the element 52 and the second condenser lens 54.

From this, l1 = Af / x1 = Af / x2 ... Formula (1)
The distance l1 from the object to be measured is obtained from the relational expression

  The position indicated by B in FIG. 2 is the same distance l1 between the position detection elements 51 and 52 and the object to be measured, but the position of the object to be measured is the position of each lens 51 and 52. This is a case where ΔA is shifted from the intermediate line 70 toward the second position detecting element 52 side. In this case, the following relational expression is established.

11: (A + ΔA) = f: x1 Formula (2)
11: (A−ΔA) = f: x2 Formula (3)
Therefore, ΔA is eliminated by the above equations (2) and (3),
l1 = 2Af / (x1 + x2) (4)
The distance l1 from the object to be measured is obtained from the relational expression

Further, by eliminating the A by the equation (2) and the equation (3),
ΔA = l1 (x1−x2) / (2f) (5)
The shift amount from the center can be calculated by the relational expression.

  The position indicated by C in FIG. 2 is the position indicated by B in that the position of the object to be measured is shifted by ΔA from the intermediate line 70 of each condenser lens 53, 54 to the second position detecting element 52 side. On the other hand, the distance to the object to be measured is 12 shorter than the position indicated by B. In other words, the position indicated by C in FIG. 2 is a case where the distance is shifted to l2 (when the object to be measured is on the ray trajectory at the position indicated by A in FIG. 2) while moving by ΔA.

  In this case, the spot position on the position detection element 52 is the same as the position indicated by A in FIG. 2, but the distance can be measured by the difference of the spot position on the position detection element 51. In this case, the following relational expression is established.

l2: (A + ΔA) = f: x1 Formula (6)
l2: (A−ΔA) = f: x2 Formula (7)
Therefore, according to the above equations (5) and (6),
l2 = 2Af / (x1 + x2) (8)
ΔA = l2 (x1−x2) / (2f) (9)
From the above relational expression, the distance to the object to be measured can be measured by receiving far infrared rays emitted from the object to be measured by the two position detection elements.

  Further, the position of the object to be measured relative to the sensor can be measured from the following relational expression.

x1 = x2 ... the object to be measured is on the intermediate line 70 of each lens x1> x2 ... the object to be measured is closer to the second condenser lens 54 than the lens intermediate line 70 x1 <x2 ... the object to be measured is the lens intermediate line In this way, the light emitted from the object to be measured is received by the first position detecting element 51 via the first condenser lens 53 and the second condenser lens 54. The focal position of the light received by the second position detection element 52 via the first light and condensed on the light receiving surfaces 61 and 62 of the first position detection element 51 and the second position detection element 52, respectively. The distance between the position detection element 51 and the second position detection element 52, the relative position of the second position detection element 52 with respect to the first position detection element 51, the relative position of the first condenser lens 53 with respect to the first position detection element 51, and Second with respect to the first position detecting element 51 Based on the relative position of the optical lens 54, when measuring the distance between the measuring object, a distance measurement with a simple structure, can be performed accurately.

  If the passive optical distance measuring sensor of the present invention is mounted on an electronic device such as a surveillance camera or a door opening / closing device, precise distance measurement can be performed with a simple configuration.

  As described with reference to FIG. 2, for example, if the passive optical distance measuring sensor of one embodiment of the present invention having two position detection elements is used, the centers of the light receiving surfaces of the two position detection elements are The distance from the line connecting the lines to the object to be measured can be accurately measured. Therefore, two passive optical distance measuring sensors according to an embodiment of the present invention having two position detection elements are prepared, and the distance in the X-axis direction is measured on the one hand, while the distance in the Y-axis direction is measured on the other hand. It can also be measured.

  That is, by disposing the passive optical distance measuring sensor of the present invention on two sides (X and Y axes) of a screen of a liquid crystal display device or the like, the coordinates (x, y) can be obtained, and a touch tablet device can be realized easily.

  1 and 2, at least one of the position detection elements is formed of an InSb-based semiconductor, so that at least one of the position detection elements receives far-infrared rays, and based on the received far-infrared rays. A person may be detected.

  In addition, the shift amount and the distance to the object to be measured are calculated by the logic of the above formulas (1) to (9), and the distance calculation unit including a microcomputer is mounted on the electronic device, so that it is easy and inexpensive. An electronic device that can measure the distance to the object to be measured can be realized.

  In addition, when the position detection element having a peak spectral sensitivity λ of 6 μm or more and 12 μm or less is incorporated in the passive optical distance sensor of the present invention, the wavelength of far infrared rays from a human body of about 9 μm can be detected with high sensitivity. Can be detected accurately, which is preferable.

DESCRIPTION OF SYMBOLS 1,51 1st position detection element 2,52 2nd position detection element 8,9 Lens part 53 1st condensing lens 54 2nd condensing lens 61 Light-receiving surface of 1st position detection element 62 Light reception of 2nd position detection element surface

Claims (10)

A first position detecting element;
A first condenser lens disposed so as to focus on the light receiving surface of the first position detecting element;
The first position detection element has a light receiving sensitivity in a far infrared region,
A passive optical distance measuring sensor, wherein a distance to a detection object is measured by receiving far infrared rays emitted from the measurement object by the first position detection element. The passive optical distance measuring sensor according to claim 1,
The passive optical distance measuring sensor, wherein the first position detecting element is formed of an InSb-based semiconductor. The passive optical distance measuring sensor according to claim 1 or 2,
A passive optical distance measuring sensor, wherein the first position detecting element is capable of detecting far infrared rays having a wavelength of about 9 μm. The passive optical distance measuring sensor according to any one of claims 1 to 3,
A passive optical distance measuring sensor, wherein the peak spectral sensitivity of the first position detecting element is 6 μm or more and 12 μm or less. The passive optical distance measuring sensor according to any one of claims 1 to 4,
The first position detection element is formed of an InSb-based semiconductor,
A second position detection element formed of an InSb-based semiconductor;
A second condenser lens disposed so as to focus on the light receiving surface of the second position detecting element,
The passive optical distance measuring sensor, wherein the light receiving surface of the first position detecting element and the light receiving surface of the second position detecting element are located on substantially the same plane.   An electronic apparatus comprising the passive optical distance measuring sensor according to any one of claims 1 to 5. The light emitted from the object to be measured is received by the first position detecting element via the first condenser lens and received by the second position detecting element via the second condenser lens,
A focal position of light collected on a light receiving surface of each of the first position detecting element and the second position detecting element; a distance between the first position detecting element and the second position detecting element; A relative position of the second position detecting element with respect to one position detecting element, a relative position of the first collecting lens with respect to the first position detecting element, and a relative position of the second collecting lens with respect to the first position detecting element; A distance measuring method comprising measuring a distance from the object to be measured based on the distance. The distance measuring method according to claim 7,
Each of the first position detecting element and the second position detecting element has a light receiving sensitivity to far infrared rays. The distance measuring method according to claim 7 or 8,
A distance measuring method, wherein at least one of the first position detecting element and the second position detecting element receives far infrared rays to detect a person.   An electronic apparatus comprising a distance calculation unit that calculates a distance by the distance measuring method according to claim 7.

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