JP2008275505A - Positional dimension measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect an edge by an optical positional dimension measuring device even when a measured object is composed of a light transmitting and/or reflecting substance. <P>SOLUTION: A projector 100 includes a semiconductor laser 130, an APC (automatic power control) circuit 150, a collimator lens 160 and a light quantity attenuation filter 170. The APC circuit 150 feedback-controls a supply current to a laser chip 135 so that laser beam output is maintained to target output based on the quantity of received light of a monitor photodiode 140. The light quantity attenuation filer 170 is arranged on a path through which disturbance light represented by reflected light 510 from the measured object 300 reaches the monitor photodiode 140, and attenuates disturbance light so as not to adversely affect feedback control by the APC circuit 150. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a position dimension measuring apparatus, and more particularly to an optical position dimension measuring apparatus.

2. Description of the Related Art An optical measuring device that measures the position / dimension of an object to be measured by detecting a change in the amount of light when an object blocks light emitted from a projector is used. In order to improve the measurement accuracy of such an optical measuring device, Japanese Patent Application Laid-Open No. 9-203613 (Patent Document 1) receives a laser beam from a light projecting unit by a polarizing beam splitter, The transmitted light is received by the first CCD, and the light reflected by the polarization beam splitter is received by the second CCD, and the signal is based on the output of the differential that takes the difference between the output of the first CCD and the output of the second CCD. A configuration for performing processing is disclosed. With this configuration, it is possible to accurately measure the dimension of the measurement target object by preventing malfunction due to the disturbance light to the light receiver even in a place with strong disturbance light such as outdoors.
JP-A-9-203613

  A semiconductor laser is generally used as the light source of the projector of such an optical measuring device. When a semiconductor laser is used as a light source, a laser chip that generates laser light and a light receiving element for monitoring (typically a photodiode) are built in the same package, and the amount of light received by the light receiving element for monitoring is determined. A configuration having an APC (Automatic Power Control) function is common. Thus, by performing feedback control of the power (current) supplied to the laser chip based on the amount of light received by the monitor light receiving element, a constant light output can be obtained even when disturbance such as temperature fluctuation occurs.

  However, in the optical measurement apparatus to which the APC function is applied, the disturbance light incident on the projector is detected by the monitor light receiving element, and the feedback control in the direction of reducing the light output is erroneously executed. There is a possibility that the intensity of the emitted light from the light source will be lowered and hinder measurement.

  For example, when the measurement target object is made of a material that transmits light, the amount of light shielded by the measurement target object is small. Therefore, the amount of light received by the light receiving unit between the existing part and the non-existing part of the measurement target object The difference is relatively small. For this reason, the difference between the threshold value of the light reception amount for detecting the edge of the measurement target object and the light reception amount at the non-existing portion of the measurement target object is inevitably small. Therefore, at the time of measuring such an object to be measured, there is a possibility that the measurement accuracy may be lowered due to a decrease in the emitted light intensity due to the influence of the disturbance light on the projector described above.

  In addition, when the measurement target object is made of a material that reflects light, the reflected light reflected by the measurement target object is incident on the projector as disturbance light, and thus the APC described above. The intensity of the emitted light from the projector due to the function is likely to decrease.

  In particular, when measuring an object to be measured that has both the property of transmitting and reflecting light, such as a glass substrate for liquid crystal material having a metal film formed on the surface except for the edge portion, the light receiving device There is a concern that not only the disturbance light but also the influence of the disturbance light on the projector causes the edge detection accuracy to be lowered and the position and / or dimension measurement accuracy to be reduced.

  The present invention has been made in order to solve such problems, and the object of the present invention is to provide a measurement target object that is made of a material that transmits and / or reflects light. An object of the present invention is to provide an optical position dimension measuring apparatus capable of accurately detecting the edge of a measurement object.

  A position dimension measuring apparatus according to the present invention includes a projector and a light receiver disposed on both sides of a region where a measurement target object exists. The projector includes a light source element capable of controlling the light output according to the supplied power, a light receiving monitor element for measuring the light output of the light source element, and a power supplied to the light source according to the light output measured by the light receiving monitor element. A power control unit to be controlled and a housing are included. The housing is configured to store at least the light source element and the light receiving monitor and to have an opening for emitting light from the light source element to the measurement target object. The light receiver includes a light receiving detection element disposed so as to face the opening with the region where the measurement target object exists interposed therebetween. The light projector is disposed at a position on a path where light from the measurement target object reaches the light receiving monitor element, and excluding a path where the light emitted from the light source element reaches the light receiving monitor element. And a light attenuation filter. Preferably, the light quantity attenuation filter is arranged on a path of the position where the light emitted from the light source element reaches the measurement target object.

  According to the position dimension measuring apparatus, the reflected light from the object to be measured is received directly after being emitted from the light source element and attenuated twice by the light amount attenuation filter without being directly incident on the light receiving monitor element of the projector. Incident to the monitor element. Therefore, since the ratio of the intensity of the reflected light to the light output of the light source element detected by the light receiving monitor element for APC is reduced, the light from the projector is affected by the influence of disturbance light on the projector represented by the reflected light. Can be prevented from decreasing. As a result, even when the measurement target object is made of a material that transmits and / or reflects light (typically glass), the edge of the measurement target object can be appropriately detected.

  Preferably, the projector further includes a collimating lens disposed between the light source element and the opening, and for converting light from the light source element into parallel light. The light amount attenuation filter is disposed between the collimating lens and the opening.

  By adopting such a configuration, it is possible to prevent the light emitted from the light source element from being refracted by the light amount attenuating filter. Therefore, the detection accuracy due to the parallelism of the emitted light from the projector being lowered by the arrangement of the light amount attenuating filter Can be avoided.

More preferably, the light amount attenuation filter is provided so as to cover the opening.
By adopting such a configuration, it is possible to provide a light quantity attenuation filter without increasing the number of parts by using the protective lens for the opening of the projector.

  Preferably, the position dimension measuring device further includes a control device for performing signal processing based on a detection result by the light receiving detection element and outputting the processing result. The control device is connected to the light receiver, but is not connected to the projector. In particular, in such a configuration, the power control unit determines the target light output set in advance in consideration of the attenuation rate by the light amount attenuation filter and the amount of received light required by the light receiving detection element, and the light output measured by the light receiving monitor element. The supplied power is controlled in accordance with the deviation.

  By adopting such a configuration, it is possible to perform measurement that is practically insensitive to disturbance light without the need to feed back the light reception output from the light receiver to the power control unit, so the connection between the projector and the light receiver is unnecessary. The degree of freedom can be improved.

  Alternatively, preferably, the projector includes a semiconductor laser configured to emit light in first and second directions in which light source elements provided as a single element are opposite to each other. The projector is configured such that the light emitted in the first direction is guided toward the opening, and the light emitted in the second direction is received by the light receiving monitor element.

  With this configuration, the reflected light from the object to be measured passes through the light amount attenuation filter and enters the light receiving monitor element, whereas the light emitted from the light source element is received more reliably. It can be detected directly by the monitor element. Therefore, it is possible to more surely prevent the light output from the projector from being lowered due to the influence of disturbance light on the projector represented by reflected light on the APC.

  More preferably, the projector includes a semiconductor laser in which a light source element and a light receiving monitor element are integrated.

  By adopting such a configuration, even if a semiconductor laser having a general configuration in which the light source element and the light receiving monitor element are integrated is applied, the reflected light from the object to be measured is not input to the light receiving monitor element. New components such as a half mirror and a new light receiving monitor element outside the semiconductor laser, without the need to place a new element such as a reflected light from the projector due to the influence of disturbance light on the projector represented by reflected light. It is possible to prevent the light output from decreasing.

  According to the position dimension measuring apparatus of the present invention, the edge of the measurement target object can be accurately detected even when the measurement target object is made of a material that transmits and / or reflects light.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and detailed description thereof will not be repeated in principle.

  FIG. 1 is a perspective view showing an overall configuration and an arrangement example of a position dimension measuring apparatus according to an embodiment of the present invention.

  Referring to FIG. 1, a position / dimension measurement apparatus 10 for measuring the position and / or dimension of a measurement target object 300 is arranged on both sides of a region where the measurement target object 300 that has been conveyed is present. The projector 100 and the light receiver 200 are provided.

  The projector 100 is connected to a power source (not shown) via a power cable 105. The light receiver 200 is connected to a controller (not shown) via a cable 205.

  As shown in FIG. 2, the housing 120 of the projector 100 is provided with an opening 110 for projecting emitted light toward the measurement target object 300. The opening 110 is provided with a light amount attenuation filter 170 described in detail later.

  Referring again to FIG. 1, the emitted light from the projector 100 enters the opening 210 provided in the light receiver 200. As will be described in detail later, a light receiving detection element is arranged in the opening 210 of the light receiver 200. The position dimension measuring apparatus 10 can detect the presence of the measurement target object 300 by detecting a change in the amount of light when the projection light from the projector 100 is blocked by the measurement target object 300 by the light receiving detection element. That is, the position and / or dimension of the measurement target object 300 can be measured by appropriately arranging a plurality of light receiving detection elements in the opening 210 in a regular manner.

  FIG. 3 is a block diagram showing the configuration of the position dimension measuring apparatus 10 according to the embodiment of the present invention.

  Referring to FIG. 3, projector 100 includes a semiconductor laser 130, an APC circuit 150, a collimator lens 160, and a light amount attenuation filter 170 provided in opening 110, which are housed in housing 120. The projector 100 is connected to a power source 400 by a power cable 105 and supplied with operating power.

  The light receiver 200 includes a light receiving detection element 250 and a processing circuit 260 stored in a housing 220. The light receiving detection element 250 is disposed corresponding to the opening 210 of the housing 220 provided so as to face the opening 110 on the light projector side across the region where the measurement target object 300 exists. A CCD image sensor is typically applied as the light receiving detection element. CCD image sensors are arranged one-dimensionally or two-dimensionally, and each CCD image sensor outputs an electrical signal (typically voltage) corresponding to the amount of received light.

  The processing circuit 260 processes the output signal from each CCD image sensor and sends the signal processing result to the controller 450 connected by the cable 205.

  For example, the controller 450 is configured as shown in FIG. 4, and includes an operation unit 452 for inputting instructions on fine adjustment of the position of the light receiver 200 and measurement condition setting, and a CCD image sensor processed by the processing circuit 260. A display unit 454 showing information corresponding to the output result is displayed. For example, information indicating the edge position of the measurement target object 300 is digitized and displayed on the display unit 454.

  The light receiver 200 is connected to the power source 410 via the controller 450. Further, the controller 450 may be connected to the computer terminal 490 so that the measurement result based on the signal processing result by the processing circuit 260 is displayed on the terminal screen.

  Referring to FIG. 3 again, the semiconductor laser 130 includes a laser chip 135 and a monitoring photodiode 140. The laser chip 135 corresponds to the “light source element” in the present invention, and the photodiode 140 corresponds to the “light receiving monitor element” in the present invention.

  As shown in FIG. 5, a general configuration in which a laser chip 135 and a photodiode 140 are integrally incorporated can be applied as the semiconductor laser 130. Laser light output from the laser chip 135 is emitted in two opposite directions. In other words, the laser light is emitted outside the semiconductor laser 130 through the glass window 137 and is also emitted in the opposite direction to enter the photodiode 140. That is, the photodiode 140 is arranged to detect the light output of the laser light output from the laser chip 135. As shown in FIG. 3, the light emitted from the glass window 137 is guided to the opening 110 in the projector 100 and is emitted from the opening 110.

  In the semiconductor laser 130 having a general structure as shown in FIG. 5, disturbance light incident on the glass window 137 from the outside is also detected by the photodiode 140. That is, if the influence of disturbance light is great, the photodiode 140 may detect the light output of the laser light from the laser chip 135 excessively than it actually is.

  Referring again to FIG. 3, the APC circuit 150 controls the supply power (typically, supply current) to the laser chip 135 based on the light output detected by the photodiode 140. The APC circuit 150 corresponds to a “power control unit” in the present invention. For example, the APC circuit 150 is configured as shown in FIG.

  Referring to FIG. 6, APC circuit 150 includes a controller 152 and a drive transistor 155. The drive transistor 155 controls the supply current to the laser chip 135 according to the drive output from the controller 152. The light output from the laser chip 135 is variable according to the supplied current (forward current), and typically has the characteristics shown in FIG.

  Referring to FIG. 7, the laser light emitted from laser chip 135 exhibits a characteristic that the light output increases as forward current I increases. Here, in the region 20 in which the forward current I is less than or equal to the threshold current (oscillation start current) Ith, the light output increases as the current increases with relatively weak spontaneous emission, while the forward current I decreases. In the region 30 that exceeds the threshold current Ith, the increase in the optical output with respect to the current increases due to the start of laser oscillation.

  Referring to FIG. 6 again, the controller 152 generates a drive output of the drive transistor 155 in accordance with a deviation of the output voltage Vdet of the photodiode 140 from the reference voltage Vref. The reference voltage Vref is set in correspondence with the output voltage of the photodiode 140 when the laser chip 135 emits the light output target value of the laser light.

  That is, when the light output detected by the photodiode 140 is lower than the light output target value, the controller 152 changes the drive signal of the drive transistor 155 so as to increase the current supplied to the laser chip 135. On the other hand, when the light output detected by the photodiode 140 is higher than the light output target value, the drive signal of the drive transistor 155 is changed so as to reduce the supply current to the laser chip 135. As a result, the APC circuit 150 implements feedback control that maintains the optical output of the laser light from the laser chip 135 at a constant value that matches the optical output target value. For example, such feedback control makes it possible to keep the laser beam constant with respect to temperature fluctuations.

  Referring to FIG. 3 again, APC circuit 150 further controls lighting of light emitting diode (LED) 122 indicating that laser light is being emitted and LED 124 indicating deterioration of semiconductor laser 130. For example, the APC circuit 150 turns on the LED 122 when the light output detected by the photodiode 140 exceeds a predetermined value. On the other hand, the APC circuit 150 turns on the LED 124 when the light output detected by the photodiode 140 does not reach the reference value for deterioration determination even when a predetermined amount of current or more is supplied to the laser chip 135.

  Laser light 500 output from the semiconductor laser 130 is converted into parallel light by the collimator lens 160 and emitted from the opening 110. The opening 110 is provided with a light amount attenuation filter 170 provided to cover the opening 110. An absorptive ND (Neutral Density) filter can be typically used as the light amount attenuating filter 170. However, in principle, any light-attenuating filter can be used as long as it attenuates light input from the opening 110 into the projector 100. All kinds of filters can be applied.

  The laser beam 500 emitted from the projector 100 is blocked by the measurement target object 300 and input to the light receiver 200 in the region where the measurement target object 300 exists. On the other hand, in the non-existing region of the measurement target object 300, the projection light from the projector 100 enters the light receiver 200 as it is without being blocked by the measurement target object 300. As described above, the amount of received light of the laser light 500 incident on the light receiver 200 is detected by the light receiving detection element 250 (CCD image sensor).

  In the case where the measurement target object 300 is made of a material that does not transmit light or is low in transmittance, the CCD image sensor 250 corresponding to the existence region and non-existence region of the measurement target object 300, respectively. The output of will be greatly different. Therefore, in this case, the edge detection of the measurement target object 300 is relatively easy.

  On the other hand, when the measurement target object 300 is made of a material that transmits light, it is relatively difficult to detect the edge portion as shown in FIG.

  Referring to FIG. 8, the horizontal axis indicates position coordinates, and the vertical axis indicates the output of the CCD image sensor at each position, that is, the amount of received light.

  When the measurement target object 300 is a substance that transmits light, there is little difference in the amount of received light detected by the CCD image sensor in both the non-existing area and the existing area of the measurement target object 300.

  On the other hand, at the edge 305 of the measurement object 300, the light 500 emitted from the projector is scattered by refraction, so that the amount of light received by the CCD image sensor arranged at the corresponding position is relatively lower than the surroundings. . Therefore, the threshold value Vth is set in accordance with the level of decrease in the amount of received light at the edge portion, and the edge detection of the measurement target object 300 is performed by comparing the output (received light amount) of each CCD sensor with this threshold value Vth. Is done. As a result of the edge detection, specifically, the position and / or size of the measurement target object 300 is detected based on which one of the arranged CCD image sensors has detected the edge.

  The level of the threshold Vth varies depending on the material, edge shape, and the like of the measurement target object 300, but when the amount of light received at the surrounding non-edge region is 100%, Vth = 70 to 75% is set. Is also present. In general, the received light amount distribution in the CCD image sensor has a noise error (white noise) of 5 to 10%. For this reason, the difficulty in edge detection increases under measurement conditions in which the measurement target object 300 is made of an object having a property of transmitting light, such as glass, and the threshold level is relatively high.

  When the measurement target object 300 is made of a material that reflects light, the laser light 500 emitted from the projector 100 is reflected by the measurement target object 300 and reflected (hereinafter simply referred to as reflected light). ) 510 goes to the projector 100. In particular, in the glass substrate for liquid crystal material, since the metal film 310 is coated on the non-edge portion, the level of the reflected light 510 becomes high.

  Referring again to FIG. 3, when the reflected light 510 from the measurement target object 300 is incident from the opening 110 toward the inside of the projector 100, it is incident toward the semiconductor laser 130 through the collimator lens 160. The Further, the reflected light 510 is input from the glass window 137 of the semiconductor laser 130 shown in FIG. 5 and reaches the photodiode 140. When such a phenomenon occurs, the amount of received light detected by the photodiode 140 becomes higher than the optical output of the laser light from the laser chip 135, so that the laser from the laser chip 135 is controlled by feedback control by the APC circuit 150. The light output may be lower than the light output target value.

  When such a decrease in laser light output occurs, the amount of light received by each CCD image sensor generally decreases in the amount of received light distribution shown in FIG. It may overlap with the value Vth level, and edge detection may not be performed normally. As an example, considering the case where Vth = 75% in FIG. 8 and the noise level is 5%, the light output from the projector 100 fluctuates by 20%, resulting in an abnormality in edge detection.

  That is, when the measurement target object 300 transmits light, edge detection becomes relatively difficult. Therefore, the edge detection accuracy is caused by the adverse effect of disturbance light on the projector 100 on the feedback control in the APC circuit 150. An error may occur. In particular, when the measurement target object 300 reflects light, the level of disturbance light to the projector 100 increases, and this problem is more likely to occur.

  Therefore, the optical position dimension measuring apparatus according to the present embodiment employs a configuration in which the light amount attenuation filter 170 is provided in the opening 110 to attenuate disturbance light incident from the outside of the projector 100.

Thereby, when the reflected light 510 is output from the projector 100 until it reaches the photodiode 140 after being output from the laser chip 135, and when it is reflected by the measurement target object 300 and input to the projector 100. Will pass through the light quantity attenuation filter 170 twice in total. Therefore, assuming that the attenuation rate by the light amount attenuation filter 170 is 1 / α, the intensity of the reflected light 510 in the photodiode 140 is 1 / α ² times that of the laser light directly reaching from the laser chip 135.

  Therefore, disturbance light incident on the projector 100, in particular, the reflected light 510 from the measurement target object 300 is suppressed from affecting the feedback control of the APC circuit 150, and laser light from the laser chip 135, that is, from the projector 100 is suppressed. It is possible to prevent the measurement accuracy from deteriorating due to a decrease in the light output of the emitted light. Accordingly, even when the measurement target object is made of a substance that transmits and / or reflects light (typically glass), the edge of the measurement target object can be appropriately detected.

  In principle, the light amount attenuation filter 170 is on the path where the light from the measurement target object 300 reaches the photodiode 140 and on the path where the light emitted from the laser chip 135 reaches the photodiode 140. What is necessary is just to arrange | position in either of the removed positions. More specifically, the light emitted from the laser chip 135 is on the path to the measurement target object 300 and the light (reflected light) from the measurement target object 300 is on the path to the photodiode 140. It may be arranged at any of the positions.

  However, by arranging the light attenuation filter 170 closer to the opening 110 than the collimating lens 160, that is, avoiding the space between the semiconductor laser 130 and the collimating lens 160, the laser light is refracted when passing through the light attenuation filter 170. Thus, it is possible to prevent the parallelism of the light emitted from the projector 100 from being lowered.

  In addition, since the opening 110 is usually provided with a protective cover for protecting the internal elements of the projector 100, the light amount attenuation filter 170 may be disposed so as to cover the opening 110 instead of the protective cover. . In this case, the light amount attenuation filter 170 can be provided without increasing the number of parts by combining the function of the protective cover. At this time, the light amount attenuation filter 170 may be disposed so as to be fitted into the opening 110, or may be attached from the inside or the outside of the housing 120.

  Note that the laser light output from the semiconductor laser 130 is emitted from the projector 100 after being attenuated by (1 / α) times in accordance with the arrangement of the light amount attenuation filter 170. Therefore, on the projector 100 side, the reference voltage Vref in the feedback control by the APC circuit shown in FIG. 5 is compared with that when the light amount attenuation filter 170 is not arranged in order to secure the light amount necessary for the measurement of the measurement target object 300. Then, the voltage may be changed to a voltage corresponding to α times the amount of light.

  In this way, the light output level of the emitted light from the projector 100 can be set appropriately without configuring a feedback system based on the light reception result on the light receiver 200 side. That is, as shown in FIG. 3, the position dimension measuring apparatus 10 can be configured without electrically connecting the projector 100 and the light receiver 200. In an application where the projector 100 and the light receiver 200 are arranged with the conveyance device of the measurement target object 300 interposed therebetween, especially in an application where the measurement target object is large, it is not necessary to make an electrical connection between the projector 100 and the light receiver 200. Demand is high from the aspect of securing the degree of freedom of placement.

  Further, as shown in FIG. 9 as a comparative example, in the projector in which the light amount attenuation filter 170 is not disposed, a normal protective lens 170 # (no light amount attenuation effect) is disposed in the opening 110. For this reason, in the projector of the comparative example, in order to suppress the adverse effect of disturbance light as in the present embodiment, the laser beam 500 from the semiconductor laser 130 is transmitted while the half mirror 190 is disposed. The reflection light 510 from the outside can be reflected so as not to enter the semiconductor laser 130 (photodiode 140) (first comparative example).

  Alternatively, instead of the arrangement of the half mirror 190, a structure is provided in which a monitoring photodiode 140 # is separately provided outside the semiconductor laser 130, and a structure that prevents the reflected light 510 from being incident on the photodiode 140 # is provided. It is also possible (second comparative example). In this case, APC circuit 150 performs feedback control based on the amount of light received by photodiode 140 #.

  In other words, according to the optical position dimension measuring apparatus according to the present embodiment, even if a general semiconductor laser (FIG. 5) incorporating the laser chip 135 and the photodiode 140 is applied, it is shown in FIG. In addition, the above-described effects can be exhibited without arranging new elements and components such as the half mirror 190 and the monitoring photodiode 140 #.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a perspective view which shows the whole structure and the example of arrangement | positioning of the position dimension measuring apparatus by embodiment of this invention. It is the figure which looked at the light projector shown in FIG. 1 from the front (light emission side). It is a block diagram explaining the structure of the position dimension measuring apparatus by embodiment of this invention. It is an external view of the controller shown in FIG. It is a figure which shows the structure of a general semiconductor laser. FIG. 4 is a block diagram illustrating a schematic configuration of an APC circuit illustrated in FIG. 3. It is a figure which shows the general output characteristic of a semiconductor laser. It is a conceptual diagram explaining the output distribution from a CCD image sensor in measuring a light-transmitting measurement target object. It is a block diagram explaining the structure of the projector shown as a comparative example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Position dimension measuring apparatus, 100 projector, 105 power cable, 110 opening part, 120 housing | casing, 130 semiconductor laser, 135 laser chip, 137 glass window, 140, 140 # monitor photodiode, 150 APC circuit, 152 controller, 155 Drive transistor, 160 collimating lens, 170 light attenuation filter, 170 # protective lens, 190 half mirror, 200 light receiver, 205 cable, 210 opening, 220 housing, 250 light receiving detection element (CCD image sensor), 260 processing circuit 300 Object to be measured, 305 Edge, 310 Metal film, 400, 410 Power supply, 450 Controller, 452 Operation unit, 454 Display unit, 490 Computer terminal, 500 Laser light (emitted light), 5 0 reflected light, I forward current (laser chip supply current), Vdet detector voltage (photodiode), Vref reference voltage (light output target), Vth a threshold (edge detection).

Claims (8)

Provided with a projector and a receiver arranged on both sides of the area where the object to be measured exists,
The projector is
A light source element capable of controlling the light output according to the supplied power;
A light receiving monitor element for measuring the light output of the light source element;
A power control unit for controlling the power supplied to the light source according to the light output measured by the light receiving monitor element;
Including at least the light source element and the light receiving monitor, and a housing having an opening for emitting light from the light source element to the measurement target object,
The receiver is
Including a light receiving detection element disposed to face the opening across the region where the measurement target object exists,
The projector is
A light amount attenuating filter disposed on a position where light from the measurement object is on a path to the light receiving monitor element and light emitted from the light source element is excluded on the path to the light receiving monitor element A position dimension measuring device further comprising:   2. The position dimension measuring device according to claim 1, wherein the light amount attenuation filter is arranged on a path of the position where light emitted from the light source element reaches the measurement target object. The projector is
A collimating lens disposed between the light source element and the opening for converting light from the light source element into parallel light;
The position dimension measuring device according to claim 1, wherein the light amount attenuation filter is disposed between the collimating lens and the opening.   The position dimension measuring device according to claim 3, wherein the light amount attenuation filter is provided so as to cover the opening. Further comprising a control device for performing signal processing based on the detection result by the light receiving detection element and outputting the processing result,
The position measurement device according to claim 1, wherein the control device is connected to the light receiver, but is not connected to the projector.   The power control unit includes a deviation between a target light output set in advance in consideration of an attenuation rate by the light amount attenuation filter and a received light amount required by the light receiving detection element, and a light output measured by the light receiving monitor element. The position dimension measuring device according to claim 5, wherein the power supply is controlled according to the following. The projector includes a semiconductor laser configured to emit light in the first and second directions in which the light source element provided as a single element is opposed to each other,
The projector is configured to guide the light emitted in the first direction toward the opening, and to receive the light emitted in the second direction by the light receiving monitor element. The position dimension measuring apparatus of any one of Claims 1-6.   The position projector according to claim 1, wherein the projector includes a semiconductor laser in which the light source element and the light receiving monitor element are integrally incorporated.

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