JP2007010556A - Optical range finding sensor, and equipment provided therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical range finding sensor capable of preventing measuring precision of a distance from getting worse along with a measured object getting distant, without bringing size enlargement and cost increase. <P>SOLUTION: Near infrared wavelength of rays emitted from an LED 1 are brought into a parallel beam by a light emitting side lens 2 to be projected to the measured object 10. A reflected beam by the measured object 10 gets incident into a PSD 5 via a photoreception side lens 3 and a prism 4. Since the prism 4 has a refractive characteristic of making a ratio of a variation of an emission angle to a variation of an incident angle get large along with the incident angle of the beam getting small, the variation of the emission angle of the emission beam from the prism 4 can be made substantially equal between the case where the measured object 10 is located in a near distance position and the case where the measured object 10 is located in a distant position, when the position of the measured object 10 is changed. The measuring precision when the measured object 10 is located in the distant position is thereby made substantially equal to that when the measured object 10 is located in the near distance position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical distance measuring sensor that detects the presence of a measurement object within a measurable range and the distance to the measurement object.

  Conventionally, as a triangulation optical distance measuring sensor, a light emitting element that emits light, a light emitting side lens that emits light from the light emitting element in parallel, and the light emitted from the light emitting side lens are emitted. A light receiving side lens for collecting the reflected light reflected by the object to be measured and a light receiving element for detecting the light collected by the light receiving side lens. (For example, refer to Japanese Patent Laid-Open No. 4-256807: Patent Document 1). This light receiving element is a PSD (Position Sensitive Photo Detector: position detecting element) that outputs a signal indicating the light irradiation position on the light receiving surface. Based on this PSD output signal, signal processing is performed using the principle of triangulation. By calculating with a circuit, the distance to the object to be measured is calculated.

  The conventional optical distance measuring sensor has a distance-output characteristic in which the distance to the object to be measured and the output value of the PSD are inversely proportional. Due to this characteristic, the ratio of the change amount of the PSD output to the change amount of the position of the object to be measured differs depending on whether the distance to the object to be measured is small or large. Specifically, when the distance to the object to be measured is small, the ratio of the change amount of the PSD output to the amount of change in the position of the object to be measured is large, and when the distance to the object to be measured is large, The ratio of the change amount of the PSD output to the change amount of the position becomes small. Therefore, as the object to be measured moves away from the optical distance measuring sensor, there is a problem that the resolution of the distance measurement value is lowered and the distance measurement accuracy is lowered.

  As a method of solving such a problem, there is a method of expanding a range with high measurement accuracy by expanding a measurable range of the optical distance measuring sensor.

However, in order to expand the measurable range of the optical distance measuring sensor, the distance between the light emitting side lens and the light receiving side lens, the distance between the light emitting element and the PSD, the distance between the light receiving side lens and the PSD, There is a need to increase the distance between. In addition, it is necessary to increase the size of the light emitting side lens and the light receiving side lens, increase the output of the light emitting element, and increase the size of the PSD. Therefore, there is a problem in that the optical ranging sensor is increased in size and cost.
JP-A-4-256807

  Therefore, an object of the present invention is to provide an optical distance measuring sensor that can prevent the measurement accuracy of the distance from decreasing as the object to be measured moves away without causing an increase in size and cost.

In order to solve the above problems, an optical distance measuring sensor of the present invention includes a light emitting element that emits light,
A light-emitting side lens through which light emitted from the light-emitting element passes,
A light-receiving side lens through which the light to be measured passes through the light-emitting side lens and is irradiated on the object to be measured, and the reflected light reflected by the object to be measured enters;
A light receiving element that receives light collected by the light receiving side lens and outputs a signal corresponding to a light receiving position on the light receiving surface;
A distance calculation circuit for calculating a distance to the object to be measured based on an output signal from the light receiving element;
In the light receiving element, the ratio of the change amount of the output to the change amount of the position of the object to be measured is such that the object to be measured is in a short distance position close to the light emitting side lens, and the object to be measured is the light emitting side. It is characterized by being substantially the same between the case where the lens is located at a long distance from the lens.

  According to the above configuration, the emitted light emitted from the light emitting element is transmitted through the light emitting side lens and irradiated to the object to be measured, and the reflected light reflected by the object to be measured is incident on the light receiving side lens. . The light condensed by the light receiving side lens enters the light receiving surface of the light receiving element. Based on the output from the light receiving element, the distance to the device under test is calculated by the distance calculation circuit. In the light receiving element, the ratio of the change amount of the output to the change amount of the position of the object to be measured is substantially the same when the object to be measured is at the short distance position and when the object is at the far distance position. Therefore, even when the object to be measured is at a long distance position, the resolution of the distance measured for the object to be measured is substantially the same as that at the short distance position. Thereby, substantially the same measurement accuracy can be obtained when the object to be measured is located at a long distance position and when it is located at a short distance position. As a result, it is possible to prevent the distance measurement accuracy from deteriorating as the object to be measured moves away without causing an increase in size and cost as in the prior art.

  The short distance position means a position as close as possible to the light emitting side lens within the measurable range where the measurement object can be measured, and the long distance position means the light emission within the measurable range. A position as far as possible from the side lens.

  Conventional optical distance measuring sensors that calculate the distance to the object to be measured using the principle of triangulation based on the output from the light receiving element that detects the light receiving position on the light receiving surface. There was nothing that accuracy did not decrease. The present inventor found that the measurement accuracy decreases as the object to be measured moves away when the ratio of the amount of change in the output of the light receiving element to the amount of change in the position of the object to be measured is that the object to be measured is at a short distance position. It has been found that the object to be measured is located at a far distance rather than a smaller point, and the present invention has been achieved based on this.

  In one embodiment, the optical distance measuring sensor is configured to detect the amount of change in the position of the measurement object when the measurement object is at the short distance position and when the measurement object is at the long distance position. The amount of movement of the light receiving position on the light receiving surface of the light receiving element is substantially the same.

  According to the embodiment, the amount of movement of the light receiving position on the light receiving surface of the light receiving element with respect to the amount of change in the position of the object to be measured when the object to be measured is at a short distance position and when the object is at a long distance position. Are substantially the same, the ratio of the change amount of the output from the light receiving element to the change amount of the position of the object to be measured can be made substantially the same.

  In one embodiment, the optical distance measuring sensor is configured to detect the amount of change in the position of the measurement object when the measurement object is at the short distance position and when the measurement object is at the long distance position. An optical element is provided between the light-receiving side lens and the light-receiving element so that the ratio of the movement amount of the light-receiving position on the light-receiving surface of the light-receiving element is substantially the same.

  According to the embodiment, the ratio of the amount of movement of the light receiving position on the light receiving surface of the light receiving element to the amount of change in the position of the object to be measured by the optical element is such that the object to be measured is at a short distance position. In the case of being in the far distance position, they are substantially the same. Therefore, the ratio of the change amount of the output from the light receiving element to the change amount of the position of the object to be measured can be made substantially the same when the object to be measured is at the short distance position and when it is at the far distance position.

  In one embodiment, the light receiving side lens has a condensing position on the light receiving surface of the light receiving element with respect to a change amount of the incident angle depending on whether the incident angle of incident light is large or small. Are substantially the same.

  According to the embodiment, the incident angle of the light incident on the light receiving side lens is large and small, corresponding to the case where the object to be measured is at a short distance position and the case where the object to be measured is at a long distance position. Arise. In the light receiving side lens, when the incident angle of incident light is large and small, the amount of movement of the condensing position on the light receiving surface of the light receiving element with respect to the amount of change in the incident angle is substantially the same. Therefore, the ratio of the change amount of the output from the light receiving element to the change amount of the position of the measurement object can be made substantially the same between the case where the measurement object is located at the short distance position and the case where the measurement object is located at the long distance position.

  In the optical distance measuring sensor according to one embodiment, the light receiving element is configured such that a normal line of the light receiving surface is substantially perpendicular to an optical axis of the light emitting side lens and the light receiving surface faces the light emitting element side. Is arranged.

  According to the embodiment, the light receiving element is arranged such that the normal line of the light receiving surface is substantially perpendicular to the optical axis of the light emitting side lens and the light receiving surface faces the light emitting element side. Therefore, the light receiving element has a ratio of a change amount of an output to a change amount of the position of the object to be measured when the object to be measured is at a short distance position and a long distance position within the measurable range. Can be made substantially the same.

An optical distance sensor according to an embodiment includes a frame on which the light receiving element is mounted.
A portion of the frame on which the light receiving element is mounted is bent at a substantially right angle with respect to other portions by a forming mold.

  According to the above embodiment, the frame is bent easily and inexpensively by using a forming mold widely used in the manufacturing process of electronic components, and the light receiving element has a normal to the light receiving surface on the light emitting side. It is possible to arrange the lens so that it is substantially perpendicular to the optical axis of the lens and the light receiving surface faces the light emitting element.

  In the optical distance measuring sensor according to one embodiment, the light receiving element has an electrical resistance value per unit area of the light receiving surface at a position far away from a position where the reflected light of the object to be measured is incident at a short distance. The position where the reflected light of the object to be measured enters is larger.

  According to the embodiment, the ratio of the amount of change in the output from the light receiving element can be made substantially the same when the object to be measured is at a short distance position and when it is at a long distance position.

  In one embodiment, the light receiving side lens has a surface shape that is asymmetric with respect to the optical axis.

  According to the embodiment, the light receiving side lens having an asymmetric surface shape with respect to the optical axis determines the position of the object to be measured between the case where the object to be measured is at a short distance position and the case where the object is at a long distance position. The amount of movement of the light collecting position on the light receiving surface of the light receiving element with respect to the amount of change can be made substantially the same. Thereby, the ratio of the change amount of the output from the light receiving element to the change amount of the position of the measurement object can be made substantially the same between the case where the measurement object is located at the short distance position and the case where the measurement object is located at the long distance position. .

  In one embodiment, the light receiving side lens has a refractive index distribution shape that is asymmetric with respect to the optical axis.

  According to the embodiment, the light receiving side lens having an asymmetric refractive index distribution shape with respect to the optical axis causes the object to be measured to be in a short distance position and a long distance position. The amount of movement of the light collecting position on the light receiving surface of the light receiving element with respect to the amount of change in position can be made substantially the same. Thereby, the ratio of the change amount of the output from the light receiving element to the change amount of the position of the measurement object can be made substantially the same between the case where the measurement object is located at the short distance position and the case where the measurement object is located at the long distance position. .

  In one embodiment of the optical distance measuring sensor, the light receiving element is mounted on a frame having a mounting area having a size larger than the length of the light receiving element in the longitudinal direction.

  According to the embodiment, the mounting position of the frame of the light receiving element can be adjusted to a desired position in the longitudinal direction of the light receiving element within the mounting area of the frame. Therefore, an optical distance measuring sensor having different measurable ranges can be manufactured at low cost using the same frame and light receiving element.

  The apparatus of the present invention includes the optical distance measuring sensor.

  According to the above configuration, the optical distance measuring sensor that can prevent the measurement accuracy of the distance from decreasing as the object to be measured moves away is provided, so that an apparatus that can operate with high accuracy while preventing an increase in size and cost is provided. can get.

  The object to be measured is not limited to an object, but also means a person, and includes any object as long as it is an object whose distance from an optical distance measuring sensor is to be measured.

  The light is not limited to light having a visible wavelength, and includes electromagnetic waves having other wavelengths such as an infrared wavelength and an ultraviolet wavelength as long as the light is irradiated and reflected on the object to be measured. .

  As described above, the optical distance measuring sensor of the present invention corresponds to the amount of change in the position of the object to be measured depending on whether the object to be measured is at a short distance position or a long distance position within the measurable range. Since it includes a light receiving element whose output change rate is substantially the same, even when the object to be measured is located at a long distance, the same measurement accuracy as that at a short distance can be obtained. Without incurring an increase in cost, it is possible to prevent the measurement accuracy of the distance from decreasing as the object to be measured moves away.

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

(First embodiment)
FIG. 1 is a longitudinal sectional view schematically showing an optical distance measuring sensor as a first embodiment of the present invention, and FIG. 2 is a plan sectional view schematically showing the optical distance measuring sensor. is there.

  The optical distance measuring sensor includes an LED (light emitting diode) 1 as a light emitting element that emits light of a near infrared wavelength, a light emitting side lens 2 that converts emitted light from the LED 1 into parallel light, and a measured object. And a PSD (position detecting element) 5 as a light receiving element that receives the light collected by the light receiving side lens 3. A prism 4 as an optical element is disposed between the light receiving side lens 3 and the PSD 5. The prism 4 has a refractive characteristic in which the smaller the incident angle of light, the larger the ratio of the change amount of the exit angle to the change amount of the incident angle. In FIG. 2, the light emitting side and light receiving side lenses 2 and 3 and the prism 4 are not shown.

  The PSD 5 is a silicon photodiode having a semiconductor P layer, an I layer, and an N layer in order from the surface side in the thickness direction, and the surface of the P layer is a rectangular light receiving surface in plan view. The light receiving surface is irradiated with light, and a photocurrent generated by photoelectric conversion is output from electrodes provided at both ends in the longitudinal direction of the light receiving surface. The current from the PSD 5 is input to a distance measuring IC (integrated circuit) 6 disposed between the LED 1 and the PSD 5, and the distance IC 6 calculates the longitudinal position of the irradiation light on the light receiving surface. It has become. Based on the position of the irradiated light on the light receiving surface, the distance to the object to be measured is calculated using the principle of triangulation. The PSD 5 is arranged with its longitudinal direction facing the LED 1.

  The LED 1, the prism 4, the PSD 5, and the distance measuring IC 6 are accommodated in a conductive casing 8, and the light emitting side and light receiving side lenses 2 and 3 are fixed to the upper side surface of the casing 8.

  In this optical distance measuring sensor, the measurable range in which the distance of the object to be measured can be measured is from the vicinity of the light emitting side lens 2 to a position about 6 m away in the light emitting direction.

  The optical distance measuring sensor having the above configuration operates as follows.

  First, the near infrared ray emitted from the LED 1 is converted into parallel light by the light emitting side lens 2 and emitted outside the casing 8. The light emitted from the light-emitting side lens 2 is irradiated on the object to be measured 10, and the reflected light reflected by the object to be measured 10 is incident on the light-receiving side lens 3. The reflected light incident on the light receiving side lens 3 is condensed, refracted by the prism 4 and irradiated onto the light receiving surface of the PSD 5. A current having a value corresponding to the irradiation position of the reflected light on the light receiving surface is output from the PSD 5. Upon receiving this current, the distance measuring IC 6 calculates a light receiving position (irradiated position of reflected light) on the light receiving surface of the PSD 5 from the current value, and based on this light receiving position, uses the principle of triangulation to measure the above measured object. The distance to the object 10 is calculated.

  The prism 4 has a refractive characteristic such that the smaller the incident angle of light, the larger the ratio of the change amount of the exit angle to the change amount of the incident angle. Thereby, the accuracy of the measured value of the distance of the object to be measured 10 can be made substantially the same between the case of being at a long distance position and the case of being at a short distance position.

  Specifically, as shown in FIG. 1, when the device under test 10 is in a short distance position near the light emitting side lens 2, the reflected light Bn1 reflected by the device under test 10 is received on the light receiving side as shown by Bn2. The light is condensed by the lens 3 and enters the prism 4 at a large incident angle as indicated by Bn3. On the other hand, when the DUT 10 is at a long distance near the limit of the measurable range, that is, when it is at a distance of about 6 m from the light-emitting side lens 2, the reflected light Bf1 reflected by the DUT 10 is The light is collected by the light-receiving side lens 3 at a small incident angle as indicated by Bf2, and is incident on the prism 4 at a small incident angle as indicated by Bf3.

  Here, the position of the device under test 10 at the short distance position and the position of the device under test 10 at the long distance position each change by the unit length in the light emission direction from the light emitting side lens 2. To do. In this case, the reflected lights Bf1 and Bn1 from the object to be measured 10 have different incident angles to the light receiving side lens 3, so that the amount of change in the emission angle from the light receiving side lens 3 is reflected from the far distance position. The light Bn1 is smaller than the reflected light Bf1 from the short distance position. Therefore, the amount of change in the incident angle to the prism 4 is smaller for the reflected light Bf2 of the object 10 to be measured at the long distance position than for the reflected light Bn2 of the object 10 to be measured at the short distance position. However, since the prism 4 has a refractive characteristic that the ratio of the change amount of the exit angle to the change amount of the incident angle is larger as the incident angle of light is smaller, the change amount of the exit angle from the prism 4 is farther. The reflected light Bf3 from the distance position and the reflected light Bn3 from the short distance position are corrected to be substantially the same. Therefore, the amount of movement of the irradiation light on the light receiving surface of the PSD 5 is substantially the same when the object to be measured 10 is at a long distance position and when it is at a short distance position. As a result, the amount of change in the output current value of the PSD 5 with respect to the amount of change in the position of the device under test 10 is approximately when the device under test 10 is at a long distance position and when it is at a short distance position. Be the same. As a result, the resolution of the distance value of the device under test 10 calculated from the output value of the PSD 5 can be made substantially the same between the case of being at a long distance position and the case of being at a short distance position. Therefore, the accuracy of the measured value of the distance of the object to be measured 10 can be made substantially the same when it is at a long distance position as when it is at a short distance position.

  Here, a comparison with the optical distance measuring sensor of the present embodiment will be made by describing a conventional optical distance measuring sensor.

  FIG. 3 is a longitudinal sectional view schematically showing a conventional optical distance measuring sensor. 3, the same components as those of the optical distance measuring sensor of FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, the conventional optical distance measuring sensor includes an LED 1, a prism 4, a PSD 5, and a distance measuring IC 6 housed in a casing 8, and a light emitting side on the top plate on the light emitting side of the casing 8. The light receiving side lenses 2 and 3 are fixed.

  Since the reflected light of the device under test 10 collected by the light receiving side lens 3 directly enters the PSD 5 without passing through the prism 4 of the present embodiment, the output value of the PSD 5 It has an inversely proportional relationship with respect to 10 distances. FIG. 4 is a graph schematically showing a distance-output characteristic that is a relationship between the distance of the DUT 10 and the output of the PSD 5. In FIG. 4, the horizontal axis is the distance from the light emitting side lens 2 to the DUT 10, and the vertical axis is the output of the PSD 5. Both the horizontal axis and the vertical axis are dimensionless quantities respectively defined by the maximum distance and the maximum output.

  The reason why the conventional optical distance measuring sensor has the distance-output characteristic as shown in FIG. 4 will be described with reference to FIG. FIG. 5 is a diagram schematically showing the principle of triangulation in the optical distance measuring sensor.

In FIG. 5, when the object to be measured 10 is at a long distance position F, the distance L19 from the center C2 of the light emitting side lens 2 to the object to be measured 10 and the reflection on the light receiving surface of the PSD 5 from the center C3 of the light receiving side lens 3. With respect to the distance L22 to the light irradiation position, the following relationship (1) is established.
L22 = α · L20 · L21 / L19 (1)
Here, α is a proportional constant, L20 is the distance between the center C2 of the light emitting side lens 2 and the center C3 of the light receiving side lens 3, and L21 is the focal length of the light receiving side lens 3.

  In FIG. 5, L18 is the distance from the light-emitting side lens 2 to the device under test 10 at the short distance position N, and L23 is the center C3 of the light receiving side lens 3 for the device under test 10 at the short distance position N. To the irradiation position of the reflected light on the light receiving surface of PSD5.

  According to the above formula (1), the distance of the irradiation position on the light receiving surface of the PSD 5 has an inverse relationship with the distance of the DUT 10. Here, the output value from the PSD 5 has a proportional relationship with the distance from the end in the longitudinal direction of the light receiving surface to the irradiation position, and therefore the output value from the PSD 5 as the DUT 10 moves away from the light-emitting side lens 2. The amount of change will decrease. As a result, as the device under test 10 moves away from the light-emitting side lens 2, the resolution of the measurement value decreases, and the accuracy of the measurement value decreases.

  On the other hand, in the optical distance measuring sensor according to the first embodiment, the prism 4 is disposed between the light-receiving side lens 3 and the PSD 5, and the prism 4 has a smaller incident angle as the incident angle of light decreases. Refractive characteristics have a large ratio of the change amount of the exit angle to the change amount. As a result, the amount of movement of the irradiation light on the light receiving surface of the PSD 5 with respect to the amount of change in the position of the device under test 10 can be measured when the device under test 10 is at a long distance position and when it is at a short distance position. Can be almost the same. As a result, the accuracy of the measured value of the distance of the device under test 10 can be made substantially the same between the case of being at a long distance position and the case of being at a short distance position. That is, it is possible to prevent the measurement accuracy from being lowered as the DUT 10 moves away from the light-emitting side lens 2.

(Second Embodiment)
FIG. 6 is a diagram showing PSD 5 provided in the optical distance measuring sensor according to the second embodiment of the present invention and a frame 15 to which this PSD 5 is die-bonded.

  The optical distance measuring sensor according to the second embodiment is different from the optical distance measuring sensor according to the first embodiment in that the prism 4 is not provided and the PSD 5 is attached at a right angle. Regarding the optical distance measuring sensor according to the second embodiment, the same reference numerals are used for the same parts as those of the optical distance measuring sensor according to the first embodiment, and detailed description thereof is omitted.

  The optical distance measuring sensor of this embodiment accommodates the LED 1, PSD 5, and distance measuring IC 6 in the casing 8, as well as the optical distance measuring sensor of the first embodiment, The light emitting side lens 2 and the light receiving side lens 3 are fixed.

  The PSD 5 is die-bonded to a frame 15 as shown in FIG. 6, and the frame 15 has a die-bonded portion 15a bonded to the PSD 5 and a mounting portion 15b bent at a right angle to the die-bonded portion 15a. By fixing the mounting portion 15b to the inner surface of the bottom plate of the casing 8, the normal line of the light receiving surface of the PSD 5 die-bonded to the die-bonding portion 15a is directed in a direction perpendicular to the optical axis of the light-emitting side lens 2. Yes.

  In the optical distance measuring sensor according to the present embodiment, the normal line of the light receiving surface of the PSD 5 is perpendicular to the optical axis of the light-emitting side lens 2, so that the object to be measured 10 is at a short distance position and at a long distance position. In some cases, the distance measurement accuracy can be substantially the same. FIG. 7 is a diagram schematically showing the principle of triangulation used in the present embodiment.

In FIG. 7, the distance L25 from the center C2 of the light emitting side lens 2 to the object to be measured when the object to be measured 10 is at the long distance position F, and the reflected light on the light receiving surface of the PSD 5 from the center C3 of the light receiving side lens 3 For the distance L29 to the irradiation position, a relationship such as the following equation (2) is established.
L29 = β · L25 · L27 / L26 (2)
Here, β is a proportional constant, L26 is the distance between the lens centers C2 and C3 of the light emitting side lens 2 and the light receiving side lens 3, and L27 is the distance between the light receiving side lens 3 and the light receiving surface of the PSD5. .

  In FIG. 7, L24 is the distance to the object 10 at the short distance position N, L25 is the distance to the object 10 at the far distance position F, and L28 is at the short distance position N. It is the distance from the center C3 of the light receiving side lens 3 to the irradiation light position of the reflected light on the light receiving surface of the PSD 5 for the device under test 10.

  As is clear from the above equation (2), the distance of the reflected light irradiation position on the light receiving surface of the PSD 5 is proportional to the distance of the DUT 10. Since the output of the PSD 5 is proportional to the distance from the end of the light receiving surface to the irradiation position, the distance of the DUT 10 and the output value of the PSD 5 have distance-output characteristics as shown in FIG. In FIG. 8, the horizontal axis is the distance from the light-emitting side lens 2 to the DUT 10, and the vertical axis is the output of the PSD 5. Both the horizontal axis and the vertical axis are dimensionless quantities respectively defined by the maximum distance and the maximum output.

  Since the optical distance measuring sensor of this embodiment has a distance-output characteristic as shown in FIG. 8, even if the object to be measured 10 moves away from the light-emitting side lens 2, the output value from the PSD 5 changes as in the prior art. The amount never decreases. As a result, the value of the distance to the device under test 10 calculated by the distance measuring IC 6 has substantially the same resolution as when the device under test 10 is at a long distance position, and has a measurement accuracy. Can be prevented.

  The frame 15 can be easily and inexpensively manufactured by bending a plate-like frame used in the first embodiment with a forming mold widely used in the manufacturing process of electronic components.

(Third embodiment)
The optical distance measuring sensor of the third embodiment is different from the optical distance measuring sensor of the first embodiment in that the prism 4 is not provided and the surface shape of the light receiving side lens is different. Regarding the optical distance measuring sensor according to the third embodiment, the same reference numerals are used for the same parts as those of the optical distance measuring sensor according to the first embodiment, and detailed description thereof is omitted.

  In the optical distance measuring sensor of the present embodiment, the light-receiving side lens that collects the reflected light of the object to be measured 10 has an asymmetric surface shape with respect to the optical axis. The surface shape of the light-receiving side lens has a refractive characteristic in which the smaller the incident angle of light, the greater the ratio of the change amount of the exit angle to the change amount of the incident angle. Thereby, the reflected light from the object to be measured 10 at the long distance position has a smaller incident angle than the reflected light from the object to be measured 10 at the short distance position, so that the distance between the long distance position and the short distance position is between. The amount of change in the emission angle from the light receiving side lens with respect to the amount of change in the position of the DUT 10 is substantially the same. As a result, the movement amounts of the irradiation light on the light receiving surface of the PSD 5 are substantially the same, and the distance measurement accuracy is substantially the same between the long distance position and the short distance position. That is, it is possible to prevent the distance measurement accuracy from being lowered as the DUT 10 moves away.

  Thus, according to the present embodiment, the functions of the axial light receiving side lens 3 and the prism 4 of the first embodiment can be obtained only by the light receiving side lens.

  Note that, instead of forming the surface shape of the light receiving side lens asymmetrically with respect to the optical axis, the effect of the present embodiment can be achieved by forming the refractive index distribution of the light receiving side lens asymmetric with respect to the optical axis. For example, the light receiving side lens is formed of a material closer to the light emitting side lens and a far side portion made of materials having different refractive indexes, and the smaller the incident angle of the light, the more the outgoing angle of the incident angle changes. Refractive characteristics that increase the rate of change may be given.

(Fourth embodiment)
The optical distance measuring sensor according to the fourth embodiment differs from the optical distance measuring sensor according to the first embodiment in that the prism 4 is not provided and the electric resistance value on the light receiving surface of the PSD is not uniform.

  In the present embodiment, the same components as those of the optical distance measuring sensor of the first embodiment are referred to by the same reference numerals, and detailed description thereof is omitted.

  The PSD 5 of the optical distance measuring sensor according to the first embodiment has the same resistance value per unit area of the light receiving surface at any position. On the other hand, in the present embodiment, the resistance value per unit area of the light receiving surface is formed so as to increase from one end to the other end in the longitudinal direction of the light receiving surface. The PSD is arranged with the end having the larger resistance value per unit area facing the light emitting side lens 2 side. That is, the resistance value per unit area of the light receiving surface is decreased as the distance from the light emitting side lens 2 increases.

  In the optical distance measuring sensor according to the present embodiment, the resistance value per unit area of the light receiving surface of the PSD decreases as the distance from the light-emitting side lens 2 increases, so the ratio of the amount of change in the output from the PSD is measured. Can be made substantially the same in the case of being in the short distance position and in the case of being in the long distance position.

  Specifically, the change amount of the emission angle from the light-receiving side lens 3 with respect to the change amount of the position of the object to be measured 10 is larger when the object to be measured 10 is at the short distance position than when the object to be measured 10 is at the long distance position. Therefore, the amount of movement of the irradiation light emitted from the light receiving side lens 3 and applied to the light receiving surface of the PSD is larger when the object to be measured 10 is at a short distance position than when the object to be measured 10 is at a long distance position. . Here, on the PSD light receiving surface, the reflected light from the object to be measured 10 at a long distance position is irradiated to a position near the light-emitting side lens 2 and the reflected light from the object to be measured 10 at the short distance position. Is irradiated to a position far from the light-emitting side lens 2. The resistance value per unit area of the light-receiving surface of the PSD is formed so as to decrease as the distance from the light-emitting side lens 2 increases. Therefore, on the light receiving surface, the irradiation light from the object to be measured 10 at a short distance moves greatly in a region having a small resistance value, and the irradiation light from the object to be measured 10 at a long distance position has a resistance value. It will move small in a large area. As a result, the rate at which the output current value from the PSD changes with respect to the amount of change in the position of the device under test 10 is when the device under test 10 is in a long distance position and in the short distance position. Are substantially the same. Therefore, the resolution of the distance value of the device under test 10 calculated from the output value of the PSD can be made substantially the same between the case of being at a long distance position and the case of being at a short distance position. As a result, the accuracy of the measured value of the distance of the device under test 10 can be made substantially the same when it is at the far distance position as when it is at the near distance position.

(Fifth embodiment)
In the fifth embodiment, the difference in measurement accuracy within the distance measurement range is reduced by changing the distance measurement range of the optical distance measurement sensor.

  9A and 9B are diagrams schematically showing the principle of triangulation in the optical distance measuring sensor according to the present embodiment.

  In the optical distance measuring sensor according to the present embodiment, the frame 25 to which the PSD 5 is die-bonded has a die bond area larger than the dimension in the longitudinal direction of the PSD 5. Accordingly, by adjusting the die bond position of the PSD 5 using the same frame 25, an optical distance measuring sensor having a different distance measuring range can be obtained.

  In FIG. 9A, when the object to be measured 10 is at a long distance position F that is a distance L45 from the center C2 of the light emitting side lens 2, and a short distance position that is a distance L44 from the center C2 of the light emitting side lens 2. The distance of the difference in the irradiation position of the reflected light on the light receiving surface of the PSD 5 with the case of N is L48. This irradiation position difference distance L48 is a distance L46 between the centers C2 and C3 of the light emitting side lens 2 and the light receiving side lens 3, a focal length L47 of the light receiving side lens 3, and a center C2 of the light emitting side lens 2 of PSD5. It is determined by the distance L50 from.

  Here, as shown in FIG. 9B, the PSD 5 is die-bonded on the same frame 25 at a position farther from the light emitting side lens 2 than in FIG. 9A and at a distance L51 from the center C2 of the light emitting side lens 2. To do. As a result, the distance measurement range can be changed without changing the distance L48 at which the reflected light is irradiated onto the light receiving surface of the PSD 5. In this case, it is only necessary to change the die bond position of the PSD 5 on the frame 25. Therefore, the distance L46 between the center C2 of the light emitting side lens 2 and the center C3 of the light receiving side lens 3, the focal length of the light receiving side lens 3, Since it is not necessary to change the length L48 of the light receiving area of the PSD 5, it is possible to prevent an increase in cost due to a change in the casing 8, the light receiving side lens 3, or the PSD 5.

(Sixth embodiment)
The self-propelled cleaner as the device of the sixth embodiment of the present invention includes the optical distance measuring sensor of the first embodiment. This self-propelled cleaner uses the optical distance measuring sensor to measure the distance to the wall of the room as an object to be measured, obstacles around the cleaner, the human body, etc. Even if it is located near the limit of the range, it can be measured with high accuracy. Therefore, it is possible to perform a cleaning operation while traveling in the room while accurately avoiding a collision with an obstacle or a human body.

  Further, the device may be a projector other than the self-propelled cleaner, for example. By providing the optical distance measuring sensor of the present invention, this projector can measure the distance to the screen or the like on which an image is to be projected with high accuracy up to the limit of the distance measuring range. According to this projector, by driving the autofocus device based on the information from the optical distance measuring sensor, it is possible to project an image with a high-precision focus on a screen located near the limit of the distance measuring range. . Therefore, a high-definition large-screen image can be displayed on the screen.

It is the longitudinal cross-sectional view which showed typically the optical ranging sensor as 1st Embodiment of this invention. It is the plane sectional view showing typically the optical ranging sensor of a 1st embodiment. It is a longitudinal cross-sectional view which shows the conventional optical ranging sensor typically. It is the graph which showed typically the distance-output characteristic between the distance of a to-be-measured object, and the output of PSD. It is the figure which showed typically the principle of the triangulation in an optical ranging sensor. It is a figure which shows PSD and a frame with which the optical ranging sensor of 2nd Embodiment is provided. It is the figure which showed typically the principle of the triangulation used in 2nd Embodiment. It is the graph which showed typically the distance-output characteristic of the optical ranging sensor of a 2nd embodiment. It is the figure which showed typically the principle of the triangulation in the optical ranging sensor of 5th Embodiment. In the optical distance measuring sensor of 5th Embodiment, it is the figure which showed typically the principle of the triangulation when the position of PSD is changed.

Explanation of symbols

1 LED
2 Light-Emitting Lens 3 Light-Receiving Lens 4 Prism 5 PSD
6 Ranging IC
8 Casing 10 Object to be measured

Claims (11)

A light emitting element that emits light;
A light-emitting side lens through which light emitted from the light-emitting element passes,
A light-receiving side lens through which the light to be measured passes through the light-emitting side lens and is irradiated on the object to be measured, and the reflected light reflected by the object to be measured enters;
A light receiving element that receives light collected by the light receiving side lens and outputs a signal corresponding to a light receiving position on the light receiving surface;
A distance calculation circuit for calculating a distance to the object to be measured based on an output signal from the light receiving element;
In the light receiving element, the ratio of the change amount of the output to the change amount of the position of the object to be measured is such that the object to be measured is at a short distance position close to the light emitting side lens, and the object to be measured is the light emitting side. An optical distance measuring sensor characterized by being substantially the same with each other when located at a far distance from a lens. The optical distance measuring sensor according to claim 1,
The movement of the light receiving position on the light receiving surface of the light receiving element with respect to the amount of change in the position of the measured object when the measured object is at the short distance position and when the measured object is at the long distance position An optical distance measuring sensor characterized in that the amounts are substantially the same. The optical distance measuring sensor according to claim 2,
Movement of the light receiving position on the light receiving surface of the light receiving element with respect to the amount of change in the position of the object to be measured when the object to be measured is at the short distance position and when the object to be measured is located at the long distance position. An optical distance measuring sensor comprising an optical element having a ratio of amounts substantially equal to each other between the light receiving side lens and the light receiving element. The optical distance measuring sensor according to claim 2,
In the light receiving side lens, the amount of movement of the condensing position on the light receiving surface of the light receiving element with respect to the amount of change in the incident angle is substantially the same for both cases where the incident angle of incident light is large and small. Optical distance measuring sensor. The optical distance measuring sensor according to claim 1,
The light receiving element is disposed such that a normal line of the light receiving surface is substantially perpendicular to an optical axis of the light emitting side lens, and the light receiving surface is directed to the light emitting element side. Type distance measuring sensor. The optical distance measuring sensor according to claim 5,
A frame on which the light receiving element is mounted;
The optical distance measuring sensor, wherein a portion of the frame on which the light receiving element is mounted is bent at a substantially right angle with respect to other portions by a forming mold. The optical distance measuring sensor according to claim 1,
The light receiving element has an electric resistance value per unit area of the light receiving surface that is reflected by a light measured at a far distance from a position where light reflected from a light measured at a short distance is incident. An optical distance measuring sensor having a larger position. The optical distance measuring sensor according to claim 2,
The optical distance measuring sensor, wherein the light receiving side lens has an asymmetric surface shape with respect to an optical axis. The optical distance measuring sensor according to claim 2,
The optical distance measuring sensor, wherein the light-receiving side lens has an asymmetric refractive index distribution shape with respect to the optical axis. The optical distance measuring sensor according to claim 1,
The optical distance measuring sensor, wherein the light receiving element is mounted on a frame having a mounting area having a dimension larger than the dimension in the longitudinal direction of the light receiving element.   A device comprising the optical distance measuring sensor according to any one of claims 1 to 10.

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