JPH11201718A - Sensor device and distance measuring equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To identify the distance to a detected object by making coaxial a light projection axis and a light reception axis. SOLUTION: Light is radiated from a light source 1 to an object detection region via a half-mirror 2 and a lens 3. The diffused reflected light from a detected object 4 is received via the half-mirror 2. A light reception section 5 is arranged to satisfy 0<Ld<=(f+La)/2, where La is the distance between the light source 1 and the lens 3, and Ld is the distance between the light reception section 5 and the lens 3. A light reception spot diameter on the light reception section 5 is changed in proportion to the distance, thereby the distance can be identified from the light reception spot diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor device for outputting a control signal for determining a distance to a detected object in a non-contact manner, and a distance measuring device for measuring the distance to the detected object.

[0002]

2. Description of the Related Art As a conventional distance measuring device, a distance measuring device based on a triangulation method has been used. As shown in FIG. 34, the light is emitted from the light projecting element 101 to the object detection area via the light projecting lens 102, and the diffuse reflection light is separated from the light projecting portion at an angle separated by a predetermined angle from the light projecting beam. The distance is detected by the lens 103 and the position detecting element 104 arranged, and the distance is detected based on the light receiving position. In an optical disk pickup or the like, the light projecting axis and the light receiving axis are made to coincide with each other, the light is irradiated on the optical disk from the light projecting section via the objective lens, and the position of the objective lens is changed so as to focus on the position of the optical disk. There is also used a method of measuring a distance based on the amount of movement. Further, Japanese Patent Application Laid-Open No. Hei 5-310816 proposes a method of measuring a light receiving spot diameter using a camera.

In Japanese Patent Application Laid-Open No. 5-264265, FIG.
As shown in the figure, the light projecting optical fiber 111 and the light receiving bundle fiber 112 are positioned at the center of the focal point f of the lens 113 at the center.
An optical displacement meter has been proposed in which an end face is arranged at the double position 2f with the same end face, and a light emitting axis and a light receiving axis are made coincident to detect a displacement of an object. This optical displacement meter detects the distance of an object within a predetermined range based on the diameter of the reflected light of the measurement object.

[0004]

However, in a distance measuring device based on the triangulation method, a reflected light in a direction inclined with respect to the projection axis from an object is received by a position detecting element or the like. It is difficult to measure the distance in a cylinder having a small radius or the distance through a small hole, as shown by a dashed line in FIG. Further, when light is incident on the end face of the detection object, a malfunction of the detection distance may occur due to the influence. In some cases, a plurality of light receiving means are provided in order to remove the influence of the edge. In this case, the detection surface of the distance measuring device is further increased, and there is a problem that there is a problem in use.

As a focus detection device used in an optical pickup or the like, a critical angle method, an astigmatism method, a knife edge method, and the like have been put to practical use. However, since such a focus detection device requires a prism, an aberration generating means, a knife edge, and the like, there are disadvantages in that a large number of optical components are required, the configuration is complicated, and assembly adjustment is difficult. Further, such a displacement sensor using focus detection can measure the distance only near the focus, and thus has a problem that the dynamic range is narrow.
Furthermore, since the objective lens is moved and the amount of movement is counted by using an encoder or the like to obtain the amount of displacement, there is a disadvantage that a movable part is required and the configuration becomes complicated. In addition, since focus detection requires a laser light source as a light source, there is a disadvantage that when a light emitting diode is used as a light source, an accurate light receiving spot cannot be obtained due to the influence of a shadow of a bonding wire, a parabola, or the like.

In Japanese Patent Application Laid-Open No. 4-310816, since the diffused light is projected on the detection object, the beam spreads as the distance increases and is affected by the edge of the object. . In addition, it is not possible to detect an object in a narrow range or a small object due to the diffused light, and it is necessary to use an optical element for focusing in the light receiving system, which is disadvantageous in that it becomes complicated.

In Japanese Patent Application Laid-Open No. 5-264265, an end face of an optical fiber for projecting light and an end face of an optical fiber for receiving light are made the same,
The distance between the end face of these fibers and the lens is set to be twice the focal length f of the lens and 2f. Therefore, as shown in FIG. 36, when the distance L to the detection object becomes larger than 2f, the spot diameter of the reflected light of the detection object increases again. Therefore, the distance to the object cannot be uniquely determined from only the spot diameter. Therefore, there is a drawback that it is necessary to detect the distance to the object within 2f by some method or to use it for an application that is guaranteed to be within 2f.

The present invention has been made in view of such a problem of the conventional distance measuring apparatus, and has a common optical axis of the projected and received beams and a distance to an object based on the diameter of the received light spot. It is intended to be able to detect or measure.

[0009]

According to a first aspect of the present invention, there is provided a light projecting device, wherein light emitted from the light projecting device is focused on a detection area, and reflected light from an object in the detection area is reflected. A lens that condenses light coaxially with the light projecting axis, and a light receiving unit that receives reflection from the object condensed through the lens,
Signal processing means for determining an object in a detection area based on a light receiving level received by the light receiving means, wherein a distance from the light projecting means to the lens is L _a , and light emitted from the lens is detected. Let L be the distance to the focal point of the area
_b , when the distance from the lens to the light receiving means is L _d and the focal length of the lens is f, 0 <L _d ≦ (f + L _a )
/ 2. In this sensor device, the signal processing means discriminates an object by discriminating a light receiving level from a predetermined threshold value to determine whether an object is present at a position closer than a predetermined distance. The distance detection processing for detecting the distance to the object based on the light receiving level from the means is included. Also, by appropriately setting the threshold level, it is possible to similarly detect when the object exists only at a predetermined distance or when the object exists within a predetermined range.

According to a second aspect of the present invention, in the first aspect, the light receiving means enters the light receiving area by a size of a light receiving spot diameter uniquely determined according to a distance to an object in the detection area. The light receiving area is arranged so as to change whether or not to perform the processing, and the signal processing means identifies whether or not an object exists within a predetermined range depending on whether or not a light receiving signal is obtained by the light receiving means. It is characterized by the following.

The invention of claim 3 of the present application is directed to claim 1 or 2
In the invention, the light receiving means has two light receiving elements whose light receiving levels change according to the light receiving spot diameter, and outputs the light receiving levels from the respective light receiving elements, and the signal processing means comprises: The control output is inverted when the two light receiving levels reach a predetermined level based on the two light receiving signals.

Further, the invention according to claim 4 of the present application is characterized in that:
A lens for converging light emitted from the light projecting means to a detection area and condensing reflected light from an object in the detection area coaxially with a light projection axis, and a linear light receiving area; A region is arranged perpendicular to the light receiving axis, a light receiving means having a position detecting element for detecting reflected light from the object condensed through the lens and detecting the optical center of gravity, and from both ends of the position detecting element. Signal processing means for detecting the distance to the object based on the optical barycenter detected by the output, wherein the distance from the light projecting means to the lens is L _a , and the detection area of the light emitted from the lens is focused. Assuming that the distance to the point is L _b , the distance from the lens to the light receiving means is L _d , and the focal length of the lens is f, each optical component is arranged such that 0 <L _d ≦ (f + L _a ) / 2. It is characterized by doing.

According to a fifth aspect of the present invention, there is provided a light projecting means, wherein light emitted from the light projecting means is focused on a detection area, and reflected light from an object in the detection area is coaxial with the light projection axis. A converging lens, and a one-dimensional or two-dimensional light-receiving element for receiving the reflected light from the object condensed through the lens, such that one of the ends and the center is aligned with the light-receiving axis. A light receiving unit disposed, and a signal processing unit that determines a distance to an object in a detection area based on the number of pixels in which each pixel of the light receiving unit is equal to or more than a predetermined light receiving amount, and The distance from the lens to the lens is L _a , and the distance from the lens to the focal point of the detection area of the emitted light is L a
_b , when the distance from the lens to the light receiving means is L _d and the focal length of the lens is f, 0 <L _d ≦ (f + L _a )
/ 2.

According to a sixth aspect of the present invention, there is provided a light emitting means which is fixed at an arbitrary position and irradiates an object in a detection area as a converged light through a lens, A light receiving means for receiving a converged light beam obtained by converging a light beam reflected from an object by the lens coaxially with the light projecting axis of the light projecting means, on an optical path between the light projecting means and the lens, and on an optical path between the light receiving means and the lens Light splitting means provided in
The distance from the light projecting means to the lens is L _a , the distance from the lens to the focal point of the converged light is L _b , the distance from the lens to the light receiving means is L _d , and the focal length of the lens is f. Then, each optical component is arranged so that 0 <L _d ≦ (f + L _a ) / 2, and the size of the spot size of the converged light is detected by the light receiving means, so that the distance information to the object in the detection area is obtained. Is obtained. Here, the light splitting means includes a half mirror and a polarizing beam splitter that transmits or reflects light in the polarization direction.

[0015]

FIG. 1 is a diagram showing a main part of an optical system of a sensor device and a distance measuring device according to the present invention. As shown in the figure, light from the light projecting surface on which the light source 1 is disposed is focused on the object detection area via the half mirror 2 and the lens 3. When the distance from the lens 3 to the detection object 4 is L, light reflected from the detection object is collected by the lens 3. Then, a part of the reflected light is reflected by the half mirror 2 and enters the light receiving unit 5. Therefore, the light receiving section 5 receives reflected light centered on the same light receiving axis as the light projecting axis. Here, L _a : the distance between the light emitting surface of the light source 1 and the lens L _b : the distance from the lens 3 to the point at which the light transmitted through the lens 3 converges L _c : the distance between the lens 3 and the light collecting surface of the light receiving unit 5 L _d: distance between the lens 3 and the light receiving surface L: the distance between the lens 3 and the detection object f: the focal point of the lens 3 the distance d: lens diameter D _a: emission diameter D _o of the light projecting element: spot diameter at the object plane D _b : spot diameter on the light-collecting surface on the object side D _c : spot diameter on the light-receiving surface on the light-receiving side D: spot diameter on the light-receiving surface The following formula is established from the lens formula.

(Equation 1) The spot diameter on the light projecting surface is given by the following equation from the lens magnification equation.

(Equation 2) The spot diameter _Do on the object plane is obtained by the following equation.

(Equation 3)

If the object to be detected is a diffused object, the light illuminating the diffused object can be considered as a light source, and the distance L between the light source and the lens 3 and the distance L from the lens 3 to the light-collecting surface on the light receiving side. _{During c,} the following equation holds according to the lens formula.

(Equation 4) Spot diameter D _c in Matashu light plane is given by the following equation.

(Equation 5)

[0017] Therefore, when placing the light-receiving surface of the light receiving portion 5 at a position behind the L _d of the lens 3, the spot diameter D of the light receiving surface obtained on the light-receiving element is given by the following equation.

(Equation 6)

Here, if L _d ≦ L _c , the light receiving spot size D is constant when the distance L to the detection surface is larger than the light projection and focusing surface L _b (L ≧ L _b ). The following describes that this relationship holds.

Since this phenomenon occurs when L ≦ L _b ,
Formula (3-1) described above is used as the spot size _Do. In order to study L _d ≦ L _c , the above-described equation (6-3) is used. Here, the equation (6-3) is transformed into
Substituting (3-2) and indicating the spot diameter D on the light receiving surface, the following equation (7) is obtained.

(Equation 7) From the above, if L _d ≦ L _c , dD / dL at L ≧ L _b
= 0, and the light receiving spot diameter D becomes constant.

FIGS. 2A to 2D show the relationship between the change in the distance L and the diameter of the light receiving spot.
In this drawing, the light line on the light projecting side and the half mirror 2 are omitted.

Next, L _d = L _a and L _a > L _d , L _a <L
_In the case of _d , curves A, B, and C are respectively shown in FIG. Thus, curve B,
In C, there is a range where the light receiving spot diameter D is constant within a certain range where L _d ≧ L _c . In curves B and C, even if the light receiving spot diameter D exceeds a certain range and the object moves away, the level at which the light receiving spot diameter expands is small. If therefore for example the total amount of light received at a distance L = L _b in the curve B is larger than the total amount of light received by _{L = L d · f / (} L d -f), the following cases the amount of light received when L = L _b it can be determined that the object is farther than L _b.
Although the reflectance of the detection object differs depending on the object, the reflectance of the diffuse object is generally in the range of 5% for a black object to 90% for a white object. Therefore, L = L _d
Black light power when the diffuse reflective object exists in is greater than the receiving power when the distance from the spot diameter is larger than the light-receiving spot diameter _{L x = L d · f /} (L d -f) is a white object , L = L _b received light amount or less of the object can be determined to be distant from the L _b.
Thus assuming the reflectivity of 5% black object at L = L _b, the maximum received light amount of L = L assuming the reflectance of 90% black object in _x, L = L towards the light receiving amount of _b is L _{x Find} Ld in a larger range. Since the amount of received light is generally considered to be inversely proportional to the square of the distance, the following equation holds as the boundary condition from the above conditions.

(Equation 8)

[0022] Now when the detected object is at the position of L _b, the light-receiving focal plane L _c is to become equal to L _a, the equation (9) holds.

(Equation 9) It detected object with respect to this focal plane L _cx of light when in the position of L _x is expressed by the following equation (10).

(Equation 10) Therefore, there is no practical problem if it is within the range of the expression (11).

[Equation 11] Even if the margin is ensured, no malfunction will occur if it is within the range of the following equation (12).

(Equation 12)

[0023] The spot diameter of the reflected light of the detection object obtained on the detector, if exceeds the distance L _b when the condition is met in the formula (12), the spot diameter of the light receiving surface is substantially constant. An example of this is shown in FIG. In this figure, curve A shows the diameter of the spot on the light receiving surface of the object having the diffusion surface, and curve B shows the diameter of the spot on the light receiving surface of the object having the mirror surface. This figure is a simulation result under the following conditions. D _a : LED emission diameter (0.15 mm) L _a : Distance between LED lenses (15 mm) L _b : Distance between lens 3 and a point where light received by lens 3 converges (10 mm) L _d : Lens 3 and light reception Distance between surfaces (13.5 mm) f: Focal length of lens 3 (13.04 mm) d: Lens diameter (8 mm) D _b : Spot diameter on condensing surface (1 mm) D: Spot diameter on light receiving surface According to the present invention, since the light receiving diameter of an object having a diffusion surface is uniquely determined according to the distance, it is determined whether or not the object exists below a certain distance or the distance of the object.

Next, a first embodiment of the present invention will be described. The basic configuration of the optical system is the same as the principle diagram of the invention described above. In this embodiment, as shown in FIG. 5, a light receiving element having a circular dead zone at the center of the light receiving surface,
Here, a distance determination sensor is configured using a photodiode. FIG. 5A shows a photodiode having a square light receiving area 6a as a whole, and FIG. 5B shows a circular light receiving area having a dead zone 7a at the center. Such a dead zone can be realized by attaching a mask M to the front surface of a photodiode serving as a light receiving element, or arranging a member serving as the mask M at a position close to the photodiode M.

FIG. 6 is a block diagram showing a configuration of a distance discriminating sensor using one such photodiode. As shown in the figure, the oscillation circuit 11 generates a light projection pulse having a constant period. The light emission pulse is emitted from the light emission circuit 12
And drives the light emitting element 13, for example, a light emitting diode, according to the light emitting interval of the light emitting pulse. In addition, a light receiving element 14 such as a photodiode (hereinafter, also simply referred to as a PD) having a dead zone is arranged at the position described above. The light receiving signal obtained by the light receiving element 14 is given to the signal processing circuit 16 via the light receiving circuit 15. The signal processing circuit 16 discriminates the presence or absence of an object by discriminating a light receiving level obtained from the light receiving circuit 15 at a timing synchronized with the light emission pulse with a predetermined threshold value. It is output as the control signal shown.

Next, the operation of this embodiment will be described. In this embodiment, if the object is far, the light receiving spot 8 is obtained only in the dead zone 7 as shown in FIG. 5C, and no output is obtained. Then, the detected object approaches
As shown in (d), when the light receiving spot enters the light receiving area 6 beyond the dead zone 7 at the center, a light receiving signal is obtained, so that the object can be identified. The set distance at which the control signal is inverted can be adjusted by bringing the light receiving surface closer to the half mirror 2 or changing the shape of the dead zone. FIG. 5
As shown in (e), a square dead zone 7b may be provided at the center.

Here, since the light receiving level changes in accordance with the reflectance of the detected object, the slope of the light receiving level with respect to the detection distance changes as shown in FIG. 7, but the distance over which the light receiving signal is obtained is constant. By setting the threshold level sufficiently low, it is possible to determine whether or not the detected object exists within a predetermined distance regardless of the reflectance of the detected object.

Next, a second embodiment of the present invention will be described. In this embodiment, as shown in FIG. 8A, the light receiving area 6c of the photodiode is arranged at a position separated from the center C of the light receiving axis by a predetermined distance, and other configurations are the same as those of the first embodiment. Same as the form. In this case, if the object is far away, the light receiving spot is small as shown in FIG. 8A, so that it does not cover the light receiving area of the photodiode, and if it is closer than a predetermined position, the photodiode as shown in FIG. Since the light receiving spot 8 is enlarged in the light receiving area 6c, it can be determined that the object is closer than a predetermined distance.

Next, a third embodiment will be described.
In the above-described first embodiment, the light receiving element has a dead zone at the center. However, as shown in FIG. 9, a mask is arranged so as to have a dead zone at the center of the light receiving region.
You may comprise directly attaching a light shielding tape etc. Further, it can also be realized by providing a mask member serving as a dead zone in a housing holding the light receiving element. Further, a plurality of light receiving elements may be arranged at the same distance from the light receiving axis C. For example, as shown in FIG. 10A, a plurality of photodiodes PD1 to PD4 are arranged at positions equidistant from the light receiving axis. In this case, the light receiving circuit 15 needs to be configured to obtain the sum of the light receiving outputs by connecting a plurality of photodiodes PD1 to PD4 in series as shown in FIG. 10B. .

Next, a method for changing the set distance at which the control signal is inverted in the first to third embodiments will be described. The change of the set distance is performed by the light emitting element 13 and the light receiving element 1.
4 or by moving a mask member provided on the front surface of the light receiving element 14. For example, when the light receiving element 14 is brought closer to the lens 3 within a range satisfying the expression (12), the light receiving spot becomes larger. Therefore, the distance setting knob and the member holding the light receiving element are linked together by a worm gear or the like so that the position of the light receiving element 14 moves perpendicularly to the light receiving axis C as shown in FIG. In this case, since the level incident on the light receiving element 14 changes with the same spot diameter, the set distance can be adjusted.

When a dead zone is provided at the center of the photodiode as the light receiving element 14 as shown in FIG. 5, the photodiode itself is moved along the light receiving axis as shown in FIG. In FIG. 12, the line on the light receiving side is shown without the half mirror. The same applies to the following figures.
For example, in FIG. 12A, the light receiving spot is small and within the dead zone, so that no light receiving signal can be obtained from the light receiving circuit 15. However, by bringing the light receiving element 14 closer to the lens 3, as shown in FIG. Becomes larger, and reflected light enters the light receiving region, so that an object can be detected. In this case, the light receiving element 14 is determined by the above equation (1).
2) It can be moved within a range satisfying.

[0032] Since the Matato optical element 13 and the distance by changing the distance itself between the lens 3 L _a, it is L _b changes, the position of the detection object is received spot diameter of the light receiving surface of constant changes . Therefore, the set distance can be adjusted even when the light emitting element itself is moved. Also in this case, it is necessary that the distance between the light receiving elements satisfies the expression (12).

When a mask member different from the photodiode is used, it is not necessary to move the photodiode which is vulnerable to noise.
The distance can be adjusted by placing the photodiode on the light receiving surface that satisfies the above equation, disposing a mask member on the front surface, and changing the position of the mask member. For example, when the mask M is arranged at the position shown in FIG. 13A, if the object is at a long distance as shown by a solid line in the figure, the mask M blocks light. Therefore, no light enters the light receiving surface as shown in FIG. When the object approaches beyond a predetermined distance, the light receiving range changes as shown by the broken line in the figure. Accordingly, in FIG. 13C, a ring-shaped reflected light is obtained around the mask M, and an object can be detected based on the reflected light. Then, when there is an object in the distance, the mask M
When the light is moved away from the light receiving surface of the light receiving element 14 from the position m1 to the position m2 as shown in FIG. 13D, reflected light of a small spot is obtained at the center of the light receiving axis as shown in FIG. Therefore, it is possible to set so that the distance at which the control output is inverted is increased.

As shown in FIGS. 14A and 14B, the mask member may be an accordion type mask M1 whose width can be changed. In this case, even if the mask M1 is arranged at a fixed position, if the width of the mask M1 is increased as shown by a broken line in FIG. No light is received by the light receiving element 14 as shown in FIG. When the width of the mask M1 is reduced as shown by the solid line in FIG. 14C, a narrow spot light is obtained at the center as shown in FIG. 14D. Therefore, the distance can be adjusted by changing the width of the mask M1. It is also possible to use a sliding door type mask instead of the accordion type mask. In this case, it is desirable to make the mask member left and right equal. However, if there is only one light receiving surface, the spot cannot be hidden unless both the left and right masks are used, so that even if there is some deviation, it can be detected without any problem. Alternatively, the position of the mask may be arranged so as to satisfy Expression (12), and the light receiving element 14 may be moved on the rear surface.

Next, a fourth embodiment of the present invention will be described. FIG. 15 is a block diagram illustrating a configuration of a sensor device in which a light receiving system is configured using two light receiving elements. In this figure, the light-emitting side circuit is the same as that of the first embodiment described above, a light-emitting circuit 12 is connected to an oscillation circuit 11, and a light-emitting element 13 is driven by a light-emitting pulse. On the other hand, the light receiving section side has two light receiving elements 21 and 22, for example, a two-division photodiode, and outputs of the amplifier circuits 23 and 2 respectively.
The signal is amplified at 4 and supplied to the subtraction circuit 25. Subtraction circuit 2
Numeral 5 subtracts the other light receiving level from the light receiving level of one light receiving element, and supplies a subtraction output to the comparison circuit 26. The comparison circuit 26 compares the obtained subtraction value with a predetermined threshold value,
The comparison output is given to the signal processing circuit 27. The signal processing circuit 27 obtains a control signal indicating object detection based on the comparison output according to the light emission pulse, and is output to the outside via the output circuit 28.

Next, the light receiving element 2 in this embodiment
The light receiving areas 1 and 22 will be described. FIG. 16 (b) shows the light receiving areas of the light receiving elements 21 and 22. It is assumed that the center circular portion in the square light receiving area is received by the light receiving element 21 and the surrounding area is received by the light receiving element 22. In this case, as shown by the solid line in FIG. 16A, if the object is far away, the light is received only by the inner light receiving element 21. As the object approaches, the dashed-dotted line from the broken line, and FIGS.
As shown in FIG. 7, the light receiving spot diameter increases. Therefore, since the light receiving levels at the inside and outside match at any position, an object detection signal can be obtained using the matching position as a threshold.

As shown in FIG. 16E, in this state, it is also possible to adjust the distance by moving the light receiving elements 21 and 22 themselves in the direction of the light receiving axis. In this way, even if the objects are at the same position, as shown in FIG. 16 (f) or (g), when the light is received by the inner and outer light receiving elements 21 and 22, and when the light is received only by the inner light receiving element 21. Therefore, the distance can be adjusted.

Here, as shown in FIGS. 17 (a) to 17 (c), the shape of the inner and outer light receiving elements is entirely circular or square.
The inner light receiving element can also be circular or square. Further, as shown in FIG. 17D, the two light receiving elements 21 and 22 can be configured to be asymmetrical with respect to the optical axis to detect an object having a large spot diameter. Further, as shown in FIG. 17E, a dead zone may be provided using a mask 29 at the center of the inner light receiving element 21. This is because the diameter of the light-receiving spot if farther than the distance L _b as shown in FIG. 4 becomes constant, but to keep the dead band region to be this constant. By doing so, it is possible to suppress imbalance between both light receiving outputs, and to expand the dynamic range of detection.

In the signal processing circuit shown in FIG.
6, the outputs of the light receiving elements 21 and 22 shown in FIG. 17 are subtracted, but the ratio between the two light receiving elements 21 and 22 is calculated, and the ratio is discriminated by a predetermined threshold value to obtain an object detection signal. Is also possible.

FIG. 18 is a block diagram showing a configuration of a distance measuring apparatus according to a fifth embodiment of the present invention. In this embodiment, the light projecting unit is the same as in each of the above-described embodiments, and the light-receiving elements 21 and 22 are used as the light-receiving elements as in the above-described fourth embodiment. The arrangement of the light receiving elements 21 and 22 is the same as in FIGS. 16 and 17 described above.
Outputs of these light receiving elements are amplified by amplifier circuits 31 and 32. These outputs are added to an adder 33 and a subtractor 34.
And calculate the sum and difference. These outputs are provided to a division circuit 35. The division circuit 35 calculates the ratio between the sum and the difference, and outputs the signal from the signal processing circuit 36.
Given to. The signal processing circuit 36 outputs a dividing calculation power to the V / I converter 37 according to the light projection pulse. The V / I converter 37 converts the obtained split calculation force into a distance signal and outputs it. In this case, a distance signal can be obtained using two light receiving elements.

FIG. 19 is a block diagram showing a configuration of a distance measuring device according to a sixth embodiment of the present invention. In this embodiment, the light projecting section is the same as in each of the above-described embodiments, and the light receiving section uses an optical gravity center position detecting element (hereinafter, referred to as PSD) 41 as a light receiving element. FIG. 20A shows the arrangement of the PSD 41. The end of the light receiving section of the PSD 41 is aligned with the center of the light receiving axis, and the longitudinal direction is arranged to be perpendicular to the light receiving axis. And PSD4
1 are converted into voltage signals Va and Vb by I / V converters 42 and 43, respectively. Outputs of the I / V converters 42 and 43 are provided to an adder 44 and a subtractor 45, and a sum and a difference are calculated. These outputs are supplied to a division circuit 46. The division circuit 46 calculates the following equation (Va−Vb) / (Va + Vb), and its output is given to the signal processing circuit 47. The signal processing circuit 47 outputs the dividing power to the V / I converter 48 according to the light projection pulse. The V / I converter 48 converts the obtained split calculation force into a distance signal and outputs it.

Next, the operation of this embodiment will be described. The PSD 41 serving as a light receiving element is arranged at the same position as the position of the light receiving element in each of the above-described embodiments. In this way, if the object is far away, its reflected light is indicated by the solid line and FIG.
As shown in (b), the reflected light enters only the portion near the light receiving axis. When the object comes closer, the light receiving spot gradually increases as shown by a broken line and a dashed line. Accordingly, as shown in FIGS. 20C and 20D, the light receiving area received by the PSD 41 is enlarged. Therefore, the position of the center of gravity of the light indicated by the arrow moves to the end portion away from the light receiving axis, and an analog signal corresponding to the distance to the detection object can be output. For this purpose, the output of the division circuit 46 may be converted into a distance signal using a table. In this case, since the distance is detected based on the ratio regardless of the reflectance of the object, the distance information can be obtained without being affected by the reflectance. Also, the I / V converters 42 and 43 are used without using the adder circuit 44 and the subtractor circuit 45 surrounded by broken lines in FIG.
May be directly input to the division circuit 46 to perform division. Further, it is needless to say that a comparator for discriminating the obtained analog signal at a predetermined level is provided, and a distance setting type photoelectric switch that outputs a control signal depending on the distance of the predetermined distance can be used.

In this embodiment, the PSD which is a light receiving element is used.
Although the end of the light receiving axis 41 is made to coincide with the light receiving axis, the light receiving axis may be arranged slightly apart from the end of the PSD 41 as shown in FIG. In this case the distance L from the lens 3 to the object is the diameter of the light-receiving spot beyond the L _b are spaced apart by the amount corresponding to the ends of the light receiving spot becomes constant. In this way, as shown in FIGS. 20 (f) to 20 (h), a change in the light receiving spot diameter with respect to the distance to the object can be detected with higher sensitivity.

Next, a seventh embodiment of the present invention will be described. In the seventh embodiment, a spot diameter is detected by arranging a one-dimensional light receiving sensor such as a CCD or a photodiode array as a light receiving element. In this case, as shown in FIG.
One-dimensional line sensor, for example, CCD5
1 is arranged so that its end and the light receiving axis coincide with each other.
In this case, the relationship between the CCD 51 and the light receiving spot indicated by a broken line according to the distance of the object is shown in FIGS.
It changes as shown in (d). Further, as shown in FIG. 21E, the center of the CCD 51 may be made to coincide with the light receiving axis. Also in this case, as shown in FIGS. 21E, 21F, and 21H, the image obtained on the CCD 51, which is a one-dimensional line sensor, changes according to the distance to the object. Therefore, as shown in FIG. 22A, the light receiving spot diameter, that is, the distance to the object can be detected by discriminating the light receiving level with a predetermined threshold value. Also, as shown in FIG. 22B, the light receiving amount M of the pixel that has obtained the maximum light receiving amount among the pixels.
By counting the number of pixels having a fixed ratio of the amount of received light with respect to AX, the spot diameter can be detected without being affected by the reflectance of the detected object. Also, by making one end coincide with the light receiving axis, the radius of the light receiving spot can be detected, and the distance to the object can be similarly detected from the radius.

Although a one-dimensional CCD line sensor is used in this embodiment, a two-dimensional CCD line sensor or a one- or two-dimensional light receiving element array may be used. A similar effect can be obtained by counting the number of light receiving elements and arrays.

Next, an eighth embodiment of the present invention will be described. In this embodiment, an optical fiber is provided at the position where the light receiving element is arranged, and is guided to the light receiving element 14. FIG. 23 shows the optical system portion. A plurality of optical fibers 61 are provided at the positions of the light receiving elements according to the first embodiment, and the light receiving elements 14 are arranged at the other end of the optical fibers 61. Other configurations are the same as those in the first embodiment. In this way, a light receiving section having a dead area at the center can be configured, and a sensor device can be configured.

An optical fiber can be used for both the light emitting and receiving sections. FIG. 24 is a sectional view of the optical system of the sensor device according to the ninth embodiment. As shown in this figure, an optical system can be configured by arranging a light projecting optical fiber 62 at the center and arranging a large number of light receiving surfaces of light receiving optical fibers 63 around the optical fiber 62. In this case, the incident end face of the light receiving optical fiber 63 is arranged at a position closer to the lens 3 than the light projecting surface of the light projecting optical fiber 62, and the light receiving face is located outside the light opening NA of the light projecting optical fiber 62. The optical fiber 63 is arranged. Also in this case, a light receiving means having a dead zone at the center can be configured. Further, if the light receiving optical fiber is divided into two optical fiber groups having different distances from the optical axis of the lens and each optical fiber group is made to enter another light receiving element, the above-mentioned two-division photodiode can be used instead. A distance measuring device can be configured. Also in this case, by taking the difference or ratio between the two, it is possible to configure so as to eliminate the influence of the reflectance of the detected object.

Next, a tenth embodiment of the present invention will be described. In the above-described embodiment, the end faces of the optical fibers for projecting and receiving light need to be different, and the structure becomes complicated. Therefore, in the embodiment shown in FIG.
The light receiving optical fiber 63 and the light receiving optical fiber 63 have the same end face, and a convex lens 64 is disposed in front of the light emitting optical fiber 62. In this way, even if the end faces of the optical fibers 62 and 63 for projecting and receiving light are the same, the light projecting surface of the light projecting element can be optically separated from the end face of the light receiving element, and the same effect as in the above-described embodiment can be obtained. can get. When a multi-core optical fiber and a CCD are used and each optical fiber is made to correspond to the pixel of the CCD at a ratio of 1: 1, the spot diameter can be measured in the same manner as the above-described measurement using the CCD, and the distance to the object can be measured. The distance can be measured.

As described above, when an optical fiber is used, light emission and reception can be separated without using a half mirror, and the optical system can be simplified. In addition, since the signal processing unit and the head unit can be separated from each other, and electrical components can be removed from the head unit, the head unit can be explosion-proof and can be reduced in size. Further, since the noise source and the light receiving element can be separated, stability during operation can be improved.

Next, an eleventh embodiment of the present invention will be described. In this embodiment, as shown in FIG. 26, an optical barycentric position detecting element (PSD) is provided near the lens 3 near the outer periphery of the light projecting element 13 so as not to be affected by the light beam of the light projecting element.
41 and a CCD 51 which is a one-dimensional line sensor. In this case, an optical system can be configured without using a light splitting unit such as a half mirror. As a result, the light use efficiency is improved, and all the optical components can be accommodated within the diameter of the lens, so that the optical components can be accommodated in a narrow space of the head portion.

Next, a twelfth embodiment of the present invention will be described. In the above-described embodiment, a half mirror is used to divide light emission and reception. In this embodiment, however, the influence of specular reflection light is removed by using a polarizing beam splitter instead of the half mirror as shown in FIG. It is something to do. If the detection object is a diffusion surface, the reflected light is reflected in a random direction and the polarization state is not preserved, so that the spot light incident on the detection object surface can be regarded as a virtual light source. However, when the detection object is a mirror surface, the reflected light is reflected while maintaining the angle of the incident light, and the polarization state is also preserved.
As described above, since the light behaves differently from the diffused light, the light receiving spot diameter on the light receiving surface may be different. Also, if the detection object is not perpendicular to the light projection axis, the reflected light will deviate from the optical axis, so that the center of the spot on the light receiving surface will deviate from the lens optical axis, causing malfunction. Therefore, FIG.
As shown in (a), a polarization beam splitter 71 is arranged in place of the half mirror 2. Then, as in the above-described embodiment, when random light is emitted from the light emitting element 13, for example, a light emitting diode, one of the polarized lights, for example, only the P-polarized light component is transmitted by the beam splitter 61,
The light is emitted to the detection object side through the lens 3. The light reflected by the detection object passes through the lens 3 and the polarization beam splitter 71.
Is transmitted or reflected, and only the S-polarized light component is obtained by the light receiving element 14. If the reflected light is specularly reflected light, its polarization state is preserved, so that the light passes through the polarization beam splitter 71 and does not reach the light receiving surface. However, if the reflected light is diffusely reflected light, the polarization is not preserved, and a part of the reflected light reaches the light receiving surface. Therefore, by using the polarization beam splitter 71 instead of the half mirror, the influence of the specularly reflected light can be easily removed, and malfunction can be suppressed. In this embodiment, it is preferable to provide a polarization filter for transmitting only P-polarized light and S-polarized light components on the front surfaces of the light emitting and receiving elements 13 and 14, respectively.

As shown in FIG. 27 (b), a light receiving element 72 having an opening at the center is provided at the position of the conventional light receiving element 14, and a second part for receiving the P-polarized light component on the outer periphery of the light projecting element 13.
By calculating the ratio of the light receiving levels of the two light receiving elements, it is possible to identify whether the detection object is a diffuse reflection object or a regular reflection object. That is, in the case of a regular reflector, light is received only by the second light receiving element 73 in the vicinity of the light emitting element, and in the case of a diffuse reflector, the light receiving levels of the two light receiving elements 72 and 73 become substantially equal. , The distance and the surface state of the detected object can be known at the same time. Also in this embodiment, a polarizing filter for transmitting a P-polarized component is provided on the front surface of the light projecting element 13, and only the S-polarized component and the P-polarized component are transmitted on the front surfaces of the first and second light receiving elements 72 and 73, respectively. It is preferable to provide a polarizing filter.

Next, a thirteenth embodiment of the present invention will be described with reference to FIGS. In this embodiment, as shown in FIG. 28, a light receiving element 21 having a circular light receiving area at the center and a light receiving element 22 having a circular or square light receiving area around the light receiving element 21 are provided. In this case, unlike the distance measuring device according to the fourth or fifth embodiment shown in FIG. 17, the spot diameter which is constant when the distance to the detection object is long as L ≧ Lb is the same as the diameter of the light receiving element 21, Alternatively, the light receiving region of the light receiving element is selected so as to have a slightly larger diameter as shown by a broken line in the drawing. Light receiving elements 21 and 22 of FIG.
Is connected to the amplifier circuits 31 and 32 as shown in FIG.
Each output is amplified and input to the addition circuit 33. The adding circuit 33 gives the added value to the dividing circuit 35. The output of the amplifying circuit 31 for amplifying the output of one of the light receiving elements 21 is also supplied to a dividing circuit 35. The dividing circuit 35 divides the amount of light received in the central light receiving region by the sum of the light receiving levels of the two light receiving elements, and outputs the signal processing circuit 36
Given to. Other configurations are the same as those of the above-described fourth and fifth embodiments. In this case, the light receiving levels of the light receiving elements 21 and 22 with respect to the distance to the detection object are shown in FIG.
0 (a), and the result of the division is shown in FIG.
The curve A is as shown in FIG. That is, the calculation result for the distance L to the detection object is close to a straight line, and the linearity is improved, so that the linearity correction is also easy. Also, unlike the fourth embodiment, since the subtraction is not performed, the operation result does not become negative, and the subsequent processing becomes easy. Further, when the set distance is changed when the sensor device determines whether the detected object is farther or shorter than the set distance, the threshold is set to an arbitrary level after the linearity is adjusted. Can be easily adjusted.

FIG. 31 is a block diagram showing the configuration of a distance measuring apparatus according to a fourteenth embodiment of the present invention. The same parts as those in the above-described thirteenth embodiment are denoted by the same reference numerals and will be described in detail. Omitted. Also in this embodiment, FIG.
Similarly, the diameter at which the light receiving spot is constant when L ≧ Lb is the same as or slightly larger than the diameter of the inner light receiving element 21. In FIG. 31, the outputs of the light receiving elements 21 and 22 are amplified by amplifier circuits 31 and 32, respectively, and the respective outputs are given to a division circuit 35. The dividing circuit 35 calculates the light receiving level at the center with the light receiving level at the surroundings, and its output is given to the signal processing circuit 36. In this case, the division result changes as shown by a curve B in FIG. Also in this case, the linearity correction becomes easy. Further, the operation result does not become negative, and the operation processing circuit can be simplified.

When a light emitting diode is used as the light projecting element 13 in each of the above-described embodiments, a shadow such as a bonding wire of the light emitting diode or a parabola for reflecting light in the horizontal or rear direction to the front surface is detected. It is conceivable that the spots can be seen on the surface or the influence thereof appears in the spot shape. In such a case, when the light receiving spot diameter is detected by the PSD or the CCD, there is a possibility that the position of the center of gravity moves or a pixel having the maximum light receiving amount is shifted from the center of the light receiving spot. So Figure 3
As shown in FIG. 2A, in the fifteenth embodiment, light emitted from a light emitting diode is condensed by a lens 81, and a light shielding plate 83 having a pinhole or an opening 82 is provided near the focal point. If the position of a pinhole or the like is a virtual light emitting surface,
The influence of the shape of the light emitting diode or the like can be eliminated. Alternatively, as shown in FIG. 32B, a diffusion plate 84 may be placed at a position where light is condensed by a lens, and the diffusion plate 84 may be used as a virtual light emitting surface. In this case, the light use efficiency can be improved as compared with the case where the shielding plate 83 is used.

Now, as shown in FIG.
For example, if L <L _b / 3, the spot diameter D on the light receiving surface becomes larger than the diameter d of the lens 3, and it becomes difficult for the light receiving element 14 to cover all of them. In addition, when the diameter of the light receiving spot increases, the amount of incident light per unit area decreases, the light receiving signal on the light receiving element surface decreases, and it becomes difficult to distinguish between the light incident state and the light shielding state. A sixteenth embodiment shown in FIG. 33 (a) solves such a problem, in which a mirror for converging the spread light receiving axis on the light receiving surface is arranged on the outer periphery of the light receiving surface. It is. As such a mirror, as shown in a perspective view in FIG. 33 (b), a truncated cone-shaped barrel 91 having a shape in which the inner wall of the cone is inclined and cut from the central axis of the cone as a reflection surface is used. The reflecting surface may be a mirror surface or a diffusing surface having a high reflectance. If a diffusion surface is used, the amount of incidence on the light receiving surface can be averaged. In this way, light spreading outward can be incident on the light receiving surface, and the amount of light received at a short distance can be improved.

[0057]

As described in detail above, according to the first to sixth aspects of the present invention, an object which reaches a predetermined distance to an object through a small hole or the like without forming a blind spot unlike the triangulation method. Can be determined. According to the fourth and fifth aspects, the distance to the object can be determined. Therefore, the size of the detection unit can be reduced, and the size of the sensor itself can be reduced. Further, even when there is an object farther than the detection range, the spot diameter does not change, so that the detection is not affected by the edge of the detection object and no malfunction occurs. Further, since it can be realized with a simple optical system, it does not require a large number of optical parts unlike an optical pickup, and does not need to provide a movable portion. Since a focal plane is not used, a light emitting diode or the like can be used as the light projecting element. Furthermore, since focused light is used at the time of distance measurement, an object that is small in a long distance can be detected, and the effect that there is no need to perform focusing on the light receiving surface is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of an optical system of a sensor device and a distance measuring device of the present invention.

FIG. 2 is a diagram showing a relationship between a distance to a detection object by the optical system and a light receiving spot diameter.

FIG. 3 is a graph showing a change in a light receiving spot diameter with respect to a distance of the optical system to a detection object.

FIG. 4 is a graph showing a simulation result showing a change in a light receiving spot diameter with respect to a distance to a detection object.

FIG. 5 is a diagram showing a relationship between a light receiving portion and a light receiving spot diameter of the sensor device according to the first embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a sensor device according to the first embodiment of the present invention.

FIG. 7 is a graph showing a change in a light receiving level with respect to a distance to an object according to the embodiment.

FIG. 8 is a diagram showing a relationship between a light receiving diameter and a light receiving spot diameter of the sensor device according to the second embodiment of the present invention.

FIG. 9 is a diagram showing a light receiving unit and a mask device of a sensor device according to a third embodiment of the present invention.

FIG. 10 is a circuit diagram showing an arrangement of light receiving elements and a light receiving circuit of a sensor device according to a third embodiment of the present invention.

FIG. 11 is a diagram showing a relationship between a position of a light receiving element and a light receiving spot diameter of the sensor device according to the first to third embodiments of the present invention.

FIG. 12 is a diagram showing a relationship between a position of a light receiving element and a light receiving spot diameter of the sensor device according to the first to third embodiments of the present invention.

FIG. 13 is a diagram showing a relationship between a mask member and a light receiving spot diameter according to the first to third embodiments of the present invention.

FIG. 14 is a diagram showing a relationship between a mask member and a light receiving spot diameter according to the first to third embodiments of the present invention.

FIG. 15 is a block diagram showing a configuration of a sensor device according to a fourth embodiment of the present invention.

FIG. 16 is a diagram showing a relationship between a light receiving element and a light receiving spot diameter of a sensor device according to a fourth embodiment of the present invention.

FIG. 17 is a diagram illustrating a relationship between a light receiving element and a light receiving spot diameter of a sensor device according to a fourth embodiment of the present invention.

FIG. 18 is a block diagram showing a configuration of a distance measuring device according to a fifth embodiment of the present invention.

FIG. 19 is a block diagram showing a configuration of a distance measuring device according to a sixth embodiment of the present invention.

FIG. 20 is a diagram showing a relationship between a PSD and a light receiving spot diameter of a distance measuring device according to a sixth embodiment of the present invention.

FIG. 21 is a diagram showing a relationship between a CCD and a light receiving spot diameter of a distance measuring device according to a seventh embodiment of the present invention.

FIG. 22 is a graph showing a change in received light intensity with respect to a position of a CCD of a sensor device according to a seventh embodiment of the present invention.

FIG. 23 is a diagram illustrating a relationship between a light receiving element and a light receiving spot diameter of a sensor device according to an eighth embodiment of the present invention.

FIGS. 24A and 24B are a sectional view and a side view showing a configuration of an optical system of a sensor device according to a ninth embodiment of the present invention.

FIG. 25 is a cross-sectional view and a side view showing a configuration of an optical system of a sensor device according to a tenth embodiment of the present invention.

FIG. 26 is a diagram illustrating a configuration of an optical system of a sensor device according to an eleventh embodiment of the present invention.

FIG. 27 is a diagram illustrating a configuration of an optical system of a sensor device according to a twelfth embodiment of the present invention.

FIG. 28 is a diagram showing light receiving elements and light receiving regions according to thirteenth and fourteenth embodiments of the present invention.

FIG. 29 is a block diagram showing a configuration of a distance measuring device according to a thirteenth embodiment of the present invention.

FIG. 30 is a graph showing a change in a light receiving level of a light receiving element with respect to a distance and a division result according to the thirteenth and fourteenth embodiments of the present invention.

FIG. 31 is a block diagram showing a configuration of a distance measuring device according to a fourteenth embodiment of the present invention.

FIG. 32 is a diagram illustrating a configuration of an optical system of a sensor device according to a fifteenth embodiment of the present invention.

FIG. 33 is a diagram illustrating a configuration of an optical system of a sensor device according to a sixteenth embodiment of the present invention.

FIG. 34 is a schematic diagram showing a configuration of a conventional triangulation distance measuring device.

FIG. 35 is a diagram showing a configuration of a conventional displacement measuring device having a light emitting and receiving axis coaxial.

FIG. 36 is a graph showing a relationship between a distance to an object and a light receiving spot in a conventional optical displacement meter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Half mirror 3 Lens 4 Detected object 5 Light receiving section 6, 6a, 6b Light receiving area 7, 7a, 7b Dead zone 8 Light receiving spot 11 Oscillation circuit 12 Light emitting circuit 13 Light emitting element 14, 21, 22, 62, 63 Light receiving Element 15 Light receiving circuit 16, 36, 47 Signal processing circuit 17 Output circuit 23, 31, 32 Amplifying circuit 25 Subtraction circuit 26 Comparison circuit 33, 44 Adder 34, 45 Subtractor 35, 46 Divider circuit 37, 48 V / I Converter 41 PSD 42, 43 I / V converter 51 CCD 61-53 Optical fiber 64 Projection lens 71 Polarization beam splitter 82 Pinhole 83 Shielding plate 84 Diffusion plate 91 Lens barrel

Claims (6)

[Claims] A lens that converges light emitted from the light projecting means to a detection area and condenses reflected light from an object in the detection area coaxially with a light projection axis; Light receiving means for receiving reflected light from the object condensed via a lens, and signal processing means for determining an object in a detection area based on a light receiving level received by the light receiving means, L _{a is} the distance from the light projecting means to the lens, L _{b is} the distance from the lens to the focal point of the detection area of the emitted light,
Assuming that the distance from the lens to the light receiving means is L _d and the focal length of the lens is f, 0 <L _d ≦ (f + L _a ) / 2.
A sensor device, wherein each optical component is arranged such that 2. The light receiving means is arranged such that whether or not the light enters the light receiving area changes depending on the size of the light receiving spot diameter uniquely determined according to the distance to the object in the detection area. 2. The sensor device according to claim 1, wherein the signal processing unit identifies whether an object exists within a predetermined range based on whether a light receiving signal is obtained by the light receiving unit. 3. . 3. The light receiving means has two light receiving elements whose light receiving level changes according to a light receiving spot diameter, and outputs the light receiving level from each light receiving element. 3. The sensor device according to claim 1, wherein the control output is inverted when the two light receiving levels reach a predetermined level based on the two light receiving signals of the means. 4. A light projecting means, a lens for converging light emitted from the light projecting means to a detection area and condensing reflected light from an object in the detection area coaxially with a light projection axis. Light-receiving means having a light-receiving area in the shape of a circle, the light-receiving area being disposed perpendicular to the light-receiving axis, and a position detecting element for detecting reflected light from the object condensed through the lens and detecting the center of gravity of the light. If, anda signal processing means for detecting the distance to an object based on the light centroid detected by the output from both ends of the position detecting device, the distance from the light projecting means to said lens L _a, The distance from the lens to the focal point of the detection area of the emitted light is L _b ,
Assuming that the distance from the lens to the light receiving means is L _d and the focal length of the lens is f, 0 <L _d ≦ (f + L _a ) / 2.
A distance measuring device, wherein each optical component is arranged such that 5. A light projecting means, a lens for converging light emitted from the light projecting means to a detection area, and condensing reflected light from an object in the detection area coaxially with a light projecting axis. A light-receiving means having a one-dimensional or two-dimensional light-receiving element for receiving reflected light from an object condensed through a lens, and having one end and the center thereof arranged so as to be aligned with a light-receiving axis; Signal processing means for determining a distance to an object in a detection area based on the number of pixels in which each pixel of the light receiving means is equal to or greater than a predetermined light receiving amount, wherein the distance from the light projecting means to the lens is L _a , the distance from the lens to the focal point of the detection area of the emitted light is L _b ,
Assuming that the distance from the lens to the light receiving means is L _d and the focal length of the lens is f, 0 <L _d ≦ (f + L _a ) / 2.
A distance measuring device, wherein each optical component is arranged such that 6. A light projecting means which is fixed at an arbitrary position and irradiates an object in a detection area as a converged light through a lens, and is disposed at an arbitrary position and transmits reflected light from the object in the detection area. Light receiving means for receiving converged light converged coaxially with the light projecting axis of the light projecting means by the lens; light branching means provided on an optical path between the light projecting means and the lens, and on an optical path between the light receiving means and the lens; L _a , the distance from the lens to the focal point of the focused light from the lens, L _b , the distance from the lens to the light receiving means, L _d , the focal point of the lens. When the distance is f, the optical components are arranged so that 0 <L _d ≦ (f + L _a ) / 2, and the size of the spot size of the converged light is detected by the light receiving unit, so that the object in the detection area is detected. It is characterized by obtaining distance information to Sensor device for.