JP3613708B2 - Cross-sectional shape measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for improving measurement accuracy of a welding laser sensor used for profiling welding or the like.
[0002]
[Prior art]
Although automatic welding equipment using welding robots has been greatly developed, in order to perform high-precision welding with higher precision at higher speeds, copy welding is performed while measuring the shape of the weld from the closest possible position by introducing a beam scanning laser sensor. What to do has come to be used.
A beam scan type laser sensor is a CCD that is arranged so that the position of a laser emitting device that emits a red or infrared laser beam and the element on which the laser beam reflected by the object is incident corresponds to the distance to the object. A linear sensor and a scanning mirror that is inserted into the laser beam path and oscillates to scan the laser beam are provided, the object is scanned, the distance to the surface is obtained, and the contour is measured.
Note that a semiconductor laser element is usually used for a laser emitting device because it is small and inexpensive and easy to control. In addition, by using a band-pass filter that matches the wavelength of the laser light that irradiates the detection optical system, the signal-to-noise ratio (S / N ratio) is improved by suppressing the influence of noise light entering from the environment, and more accurately. It is configured to be able to make accurate measurements.
[0003]
However, even if the intensity of the laser beam does not change, the intensity of the reflected light incident on the CCD sensor varies depending on the surface condition such as the material of the object and the direction of the surface on which the laser beam strikes, so that stable surface shape measurement cannot be performed. That is, if the reflected light is too strong, it is difficult to accurately determine the actual position because a large number of CCD elements are sensitive and the outline is represented by a thick line. Further, if the reflected light is weak, the CCD element output becomes lower than the detection threshold and the contour line is cut, so that a correct shape cannot be detected.
Conventionally, in laser distance meters, etc., a method has been used in which the laser output and the exposure time of the detection element are adjusted in accordance with the amount of reflected light from the measurement target to cope with variations in light intensity such as saturation of the light receiving element and lack of reflected light. It was. Since this method measures the target distance on the assumption that the object does not move, there is no time limit.
[0004]
However, the beam scanning laser sensor for welding performs distance measurement several hundreds of times corresponding to the resolution in the scanning direction during scanning. Further, in order to detect the reflection position when the laser beam is irradiated, the received light amount scanning is performed on the light receiving elements arranged in a straight line by the number corresponding to the distance resolution. It takes about several tens of microseconds to scan the received light amount once.
Since the light irradiation position changes during optical scanning, and the amount of incident light varies according to the change in the surface of the measurement object, controlling the laser output immediately in accordance with the amount of light incident on the CCD element is the calculation speed of the control circuit and the optimum From the viewpoint of the complexity of the calculation logic of the adjustment amount, it was not easy.
[0005]
In addition, since the operating temperature of the semiconductor laser element used in the laser radiation device is narrow, for example, 0 to 40 ° C., the welding laser sensor that is located near the weld and is exposed to a high temperature is compulsorily kept within the operating range. Cool to use. When used in a place where the outside air temperature is low, the device may not operate until the element is sufficiently warmed, such as at the start.
Furthermore, the temperature of the semiconductor laser is greatly affected by the temperature, and the peak wavelength of the laser beam usually fluctuates by about 5 nm for a temperature difference of 10 ° C., whereas the actual temperature of the sensor varies depending on the environment, so the transmission wavelength width of the bandpass filter is 20 nm. It is necessary to take some wide. For this reason, the removal rate of noise light entering from the environment is lowered, and the SN ratio cannot be sufficiently suppressed. Therefore, it is difficult to clearly define the contour line in order to increase the detection sensitivity by sufficiently increasing the laser high intensity and lowering the threshold value used for the contour line detection.
[0006]
[Problems to be solved by the invention]
Therefore, the problem to be solved by the present invention is that, in a beam scan type laser sensor provided close to a welded part such as an automatic scanning welding apparatus, when reflected light incident on the sensor fluctuates due to a change in conditions of a measurement target part. Is to provide a device that can measure the weld shape with high accuracy, and to provide a device that can accurately measure the shape even when using a laser generating element that is susceptible to temperature, such as a semiconductor element. is there.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a cross-sectional shape measuring apparatus according to the present invention has a laser radiation device, a one-dimensional optical sensor, and a target surface in one direction while guiding laser light from the laser radiation device to the measurement target. In A scanning mechanism that scans and reflects a laser beam reflected from the surface to a one-dimensional optical sensor, and moves the scanning mechanism relative to an object to scan a necessary area surface; Adjust the amount of incident light by adjusting the output of the laser radiation device and the exposure conditions of the one-dimensional photosensor. With an incident light quantity adjuster, The incident light amount controller includes a storage device that stores a functional relationship between an operation amount for adjustment and an incident light amount, In conjunction with scanning by the scanning mechanism, the one-dimensional photosensor detected when the laser beam irradiation direction was the same as before. Using the received light amount of the entire one-dimensional photosensor as a brightness evaluation value, the brightness evaluation value Adjust the amount of incident light in the direction that approaches the target value For adjusting the amount of incident light based on the adjustment value sequence prepared using the functional relationship It is characterized by that.
[0008]
As the scanning mechanism, a mechanism that uses a galvano mirror or the like to obtain the laser irradiation direction directly from the direction of the mirror surface can be used. Alternatively, a mechanism that uses a scanning mirror with a swing angle sensor can be used. it can. This scanning mirror is oscillated about the rotation axis, and the oscillation angle can be detected by an angle sensor to know the laser beam emission direction. The detected light amount when the scanning mirror is oscillating and when the same phase angle is taken before can be used as the reference light reception amount used for adjusting the incident light amount.
The adjustment of the amount of incident light may be performed on both the forward and backward paths of the scanning mirror.
[0009]
The cross-sectional shape measuring apparatus of the present invention is sensitive to reflected light by irradiating the surface of an object with laser light and causing the reflected light to enter, for example, a one-dimensional optical sensor in which CCD elements are arranged in a row through a measurement optical system. The reflection position of the laser beam is calculated from the element position. Contour lines for each scan are created by aggregating the data of the reflection positions obtained in this way, that is, the surface position of the object in the scan direction of the laser beam. Furthermore, the surface shape is measured by forming a contour line on the entire surface of the object while moving the apparatus forward.
[0010]
According to the cross-sectional shape measuring apparatus of the present invention, the state of the measurement object that changes along the scanning direction of the apparatus is acquired as received light amount information by a one-dimensional optical sensor. Therefore, when performing a new scanning, the amount of incident light of the one-dimensional photosensor is set so that the light amount level is lowered at a position where the reflected light is bright and the light amount level is raised at a position where the reflected light is dark based on previously received light amount information. Adjust. As described above, when the received light amount of the one-dimensional photosensor approaches a predetermined target value, and the received light amount is leveled and the detection sensitivity is maintained at an appropriate level, the light cutting line on the surface of the object detected by the sensor is detected. However, since an appropriate thickness is maintained, the accuracy of object shape measurement can be ensured.
[0011]
Since the surface state of the object changes along the scanning direction of the laser beam, it is necessary to adjust the amount of incident light for each irradiation direction of the laser beam. Therefore, in the present invention, the incident light amount is adjusted in a direction in which the received light amount approaches a predetermined value in a new measurement based on the received light amount information in the same irradiation direction previously acquired by the one-dimensional photosensor.
The amount of incident light can be adjusted by changing the drive current of the laser generating element, the laser pulse lighting time, the camera exposure time, or a combination of these factors. When the control is performed using both the laser generating element and the optical sensor, the adjustment range of the incident light quantity can be expanded to have a larger dynamic range.
[0012]
When using a scanning mirror with a swing angle sensor in the scanning mechanism, the swing angle is detected by the angle sensor to define the laser beam radiation direction, and the amount of light detected when the same phase angle is taken previously. The incident light amount can be adjusted as a reference light reception amount used for adjusting the incident light amount.
In the method of scanning by scanning the scanning mirror, the surface contour of the object can be measured both in the reciprocal direction because it appears alternately and shows a symmetric motion in the forward path and the backward path. In this case, it is preferable to adjust the amount of incident light by evaluating the amount of received light for each swing angle independently for the forward path and the return path.
[0013]
The reflection position for each laser irradiation position is obtained from the position of the light receiving element sensitive to light. Therefore, if there is a constant amount of incident light, the amount of light received by the entire one-dimensional photosensor is constant. Therefore, the reference light receiving amount for adjusting the amount of incident light may be obtained by integrating the outputs of all the light receiving elements constituting the one-dimensional photosensor, or an integrated value or an average value.
Of course, for the sake of simplicity, it is also possible to use the detected light amount of the light receiving element having the highest intensity.
[0014]
Furthermore, the incident light amount adjuster may be provided with a storage device that stores a conversion table that describes an adjustment amount corresponding to the received light amount, and may adjust the incident light amount with reference to the conversion table. This is because it is preferable to select and use an appropriate function depending on the case because the functional relationship differs depending on the material and shape of the object. Even when the object changes, an appropriate function can be easily set by software means, so that a wide variety of objects can be dealt with.
The incident light amount adjustment value may be calculated by processing the received light amount information obtained when the irradiation direction is the same in the previous scanning, so that each calculation may be performed during one scanning period. . Therefore, the measurement result input process and the adjustment value calculation can be executed in parallel.
[0015]
Further, in order to solve the problems in the present invention, a cross-sectional shape measuring apparatus of the present invention uses a semiconductor laser generating element in a laser emitting device, and a temperature detecting element and a heat transfer are provided in a housing of the semiconductor laser generating element. A temperature regulator is provided in close contact with the elements and connected thereto. The temperature controller adjusts the heat generation / absorption amount of the heat transfer element based on the output of the temperature detection element, thereby maintaining the semiconductor laser generation element at a predetermined temperature. Then, in order to suppress the temperature fluctuation of the characteristics of the semiconductor laser generating element, the transmission wavelength width of the band-pass filter provided in the one-dimensional photosensor can be narrowed, and the influence of noise light leaking from the environment can be removed. Therefore, the S / N ratio of the measurement output of the optical sensor is remarkably improved, the contour is sharpened, an accurate contour can be obtained, and the object surface shape can be accurately defined.
[0016]
Use of a Peltier effect element for the heat transfer element is convenient because it enables both heating and cooling by controlling the direction of the current.
By adopting such temperature control of the semiconductor laser generator and adjustment of the amount of incident light, it is possible to measure contours with higher accuracy even when copying and placing the device in a high-temperature environment near the weld. Thus, high quality welding can be performed.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on examples with reference to the drawings.
FIG. 1 is a block diagram of a cross-sectional shape measuring apparatus according to the present embodiment, FIG. 2 is a conceptual diagram illustrating a configuration of a sensor head used in the present embodiment, and FIG. 3 is a drawing illustrating an example of an image composition result in the present embodiment. 4 is a distribution diagram showing an example of a change in the amount of received light in the laser scanning direction in this embodiment, FIG. 5 is a drawing showing an example of a conversion table used for obtaining a control amount in this embodiment, and FIG. 6 is an incidence in this embodiment. FIG. 7 is a flowchart for explaining the relationship between image scanning and control amount determination timing, FIG. 8 is a block diagram of a temperature control system of a laser projector used in this embodiment, and FIG. 9 is a laser projector. FIG. 10 is a diagram illustrating the relationship between the laser wavelength distribution and the wavelength characteristics of the band-pass filter for explaining the temperature control effect of the laser projector.
[0018]
As shown in FIG. 1, the cross-sectional shape measuring apparatus according to the present embodiment includes a sensor head 1, a controller 2, and a display 3 of a laser sensor, and measures the surface shape of a measurement object 4.
As shown in FIG. 2, a laser projector 11, a one-dimensional optical sensor 12, and a scanning mirror 13 are incorporated in the laser head 1. The laser projector 11 generates a red laser having a wavelength of 690 nm using a semiconductor laser generating element. The generated laser beam is applied to the measurement object 4. The light reflected from the surface of the measuring object 4 enters the one-dimensional optical sensor 12 via the condensing optical system 14.
[0019]
In addition, a band-pass filter that passes through the region sandwiching the wavelength of the irradiated laser light is provided in the incident optical path of the one-dimensional photosensor, and noise light entering from the surroundings is rejected to improve the signal-to-noise ratio. In this way, more accurate measurement can be performed.
The one-dimensional optical sensor 12 is a linear sensor in which a number of CCD elements are arranged in a straight line. When laser reflected light is incident on the sensor by the condensing optical system 14, the optical center of the condensing optical system 14 and the laser irradiation position are connected. Since light irradiates the CCD element on the straight line, the position of the received CCD element corresponds to the laser irradiation position, and the surface position of the object is known based on the position on the array of elements having a large amount of incident light. be able to.
[0020]
In order to measure the cross-sectional shape of the object, it is necessary to scan the measurement mechanism using the triangulation in the direction of the cutting plane and to arrange the position measurement result along the scanning line. For this purpose, a scanning mirror 13 is interposed in the laser beam path. The laser beam emitted from the laser projector 11 is refracted to irradiate the measuring object 4, and the light reflected and returned from the surface of the measuring object is refracted again and incident on the one-dimensional optical sensor 12. Since the scanning mirror 13 reciprocates around the swing shaft 15, the laser beam scans in a direction perpendicular to the swing shaft, and the surface position measurement results are sequentially acquired along the scanning direction. Although not shown in the figure, since the oscillation of the scanning mirror 13 changes in a sinusoidal function, the time and the laser irradiation direction are not necessarily linearly related, so the direction of the scanning mirror reflecting surface is actually detected. The measurement accuracy is ensured by defining the measurement direction.
[0021]
With the above configuration, one cross-sectional shape can be measured by one scan, and the surface shape of the object can be measured as a surface by continuously scanning while moving the measuring device.
FIG. 3 is a diagram showing an example in which one cross-sectional shape measurement result obtained by one laser scan is displayed.
The distance from the light spot appearing on the surface of the object when the scanning mirror 13 has a certain angle to the instrument is a triangulation method using the position in the element array in the linear optical sensor 12 of the CCD element having a large amount of light received. It can ask for. The position of the received element can be obtained by scanning the optical sensor and observing the output of each element.
[0022]
Further, when the scanning mirror 13 is swung and scanned over the entire measurement range, and the result of repeating the above measurement for each predetermined irradiation angle is developed and shown on the display screen, the light spots as shown in FIG. 3 are continuous. An outline appears. This outline represents the result of radial measurement of the distance from the swinging axis 15 of the scanning mirror to the surface of the object for one cross section of the object.
The actual cross-sectional shape information is preferably given as, for example, a contour expressed by a height from one plane by performing simple conversion processing using information on the orientation of the mirror surface.
[0023]
In addition, since the surface characteristics of the object 14 are not constant, when light of the same intensity is irradiated, the surface reflectance and the inclination of the reflecting surface differ depending on the location, and the intensity of the reflected light incident on the photosensor changes.
For example, when the surface of the object is tilted with respect to the incident laser light, the incident light per area becomes weak, and the reflected scattered light energy that the optical sensor catches becomes small. For this reason, the amount of accumulated charge in the CCD element is reduced, and the contour line may be interrupted depending on the setting of the threshold value. Further, when the light absorption rate on the surface of the object is high, the amount of light incident on the optical sensor is reduced, making it difficult to detect the contour line. Further, even when the light reflectance is high, the amount of light incident on the optical sensor is reduced depending on the orientation of the surface.
On the other hand, depending on the surface state of the object, a large amount of light energy is incident on the optical sensor, and the CCD element saturates or many neighboring CCD elements generate detection output and become a thick detection band. It becomes difficult to know.
[0024]
When the output of the CCD element of the optical sensor is plotted in the scanning direction of the laser light, it can be seen that the incident light intensity, which is the brightness evaluation value, changes as shown in FIG. 4, for example. The output value to be plotted may be a value obtained by integrating the outputs for the entire photosensor in which the CCD elements are arranged in one row, or an average output value of the CCD elements, or an output value of the CCD element having the maximum output in one row. It may be.
In the cross-sectional shape measuring apparatus of the present embodiment, a predetermined reference value is set as the brightness evaluation value, the amount of light incident on the CCD element is reduced for bright areas higher than the reference value, and for dark areas lower than the reference value. Adjustment is made to increase the amount of incident light on the CCD element.
[0025]
The adjustment is performed by the controller 2 having the CPU board 21, the image input board 22, the interface board 23, and the bus 24 connecting them, and the light obtained when having the same irradiation angle phase in the previous laser light scan. The sensor light reception amount is used as a brightness evaluation value, and the evaluation value is adjusted by adjusting the output of the laser generating element and the exposure condition of the optical sensor in a direction approaching the reference value.
Since the laser light scan is repeated at a very high speed, the measurement target position does not change much between the previous scan and the current scan, so that the current measurement condition can be improved by the improvement operation based on the previous measurement condition.
Also, as the measurement device moves and the measurement position changes, the surface properties of the measurement object change, but since the measurement results obtained in the previous scan are used, accurate adjustments that follow the position change must be made. Can do.
[0026]
FIG. 5 shows an adjustment procedure performed in this embodiment.
That is, when measurement starts, the laser is scanned for one section based on the initial conditions. First, the measurement target region is irradiated with a laser beam (S1), the measurement result of the optical sensor is recorded for each irradiation point (S2), and it is determined whether or not the first laser beam scan is completed (S3). . The steps S1 and S2 are repeated as long as the process is not completed, and the process proceeds to step S4 after acquiring information for one screen.
[0027]
When one laser beam scan is completed, a cross-sectional contour line as shown in FIG. 3 is obtained, so that the contour line information is captured by the image input board 22 and the captured contour is captured by the image processing circuit provided on the CPU board 21. Image processing including conversion processing is performed on the line information to obtain information representing the surface shape of the object in real space.
Information on the surface shape of the object is sent to the interface board 23 and displayed on the display 3 or supplied to a welding scanning control device (not shown). Further, the brightness distribution along the scan line obtained by the image processing is detected (S5), the brightness evaluation value is compared with the reference value, and the amount of light incident on the optical sensor 1 is adjusted based on the deviation. Is calculated (S6).
[0028]
The incident light quantity of the one-dimensional photosensor can be controlled by adjusting the input current of the laser projector 11, the duty ratio of laser pulse lighting, the exposure time of the one-dimensional photosensor 12, or a combination thereof.
As conceptually shown in FIGS. 6 (a), 6 (b), and 6 (c), due to the properties of the measurement object 4 and the effects of the characteristics of the one-dimensional optical sensor 12 and the laser projector 11, the respective operation amounts and the one-dimensional light. Since there is a different functional relationship between the incident light amounts of the sensors 12, a conversion table or calculation formula obtained in advance is held in a storage device provided in the CPU board 21, and the conversion table and calculation formula are referred to. Therefore, it is necessary to obtain an appropriate adjustment value for each.
[0029]
Using the adjustment value sequence prepared in this way, the light output control of the laser projector 11 is performed at each timing of the laser scan, and the object 4 is irradiated with the laser beam emitted (S7). Further, image data is taken in for the CCD element array of the one-dimensional photosensor 12 at each timing of laser scanning (S8).
The one-dimensional optical sensor 12 may be one that adjusts the shutter speed, for example, using the adjustment value and performs exposure time control. When the incident light amount adjustment is performed using both the laser projector 11 and the one-dimensional optical sensor 12, there is an advantage that the adjustment range becomes extremely large.
[0030]
It is determined whether or not the laser beam scan has been completed for one cross section, and the above steps S7 and S8 are repeated unless it is completed, and when information for one screen has been acquired, the process proceeds to step S4 (S9). Shape information is provided to the welding control device (S4), and adjustment values for the next laser scan are prepared (S5, S6).
As shown in FIG. 7, the light spot distance is usually measured at a portion where the speed is relatively constant by using only one of the forward path and the backward path while the laser beam scans the object by the reciprocating scanning mirror 13. Is configured to do. Therefore, the adjustment value supplied to the control mechanism is calculated while the scanning mirror 13 returns to the measurement start position after the light sensor 12 has finished measuring the light spot distance in the previous scanning, and the next image measurement is performed. It is preferable that everything is prepared when starting.
[0031]
However, since the actual adjustment is performed at each phase position during scanning, it is sufficient if the adjustment data is ready by that time. Needless to say, it may be calculated and supplied to the control mechanism.
Further, if the cross-sectional shape is measured in both the forward path and the return path of the scanning mirror 13, the measurement density is doubled, so that a more precise shape measurement can be performed. When the measurement is performed both in the reciprocal direction, the scanning direction is reversed in the forward path and the backward path. Therefore, it is necessary to calculate the adjustment values separately and arrange the adjustment value data strings in the same direction. Preferred for simplicity.
[0032]
Since the characteristics of the semiconductor laser element change remarkably with temperature, the range in which it can be used stably is limited to, for example, 0 to 40 ° C., and the peak wavelength of the laser light varies even within the usable range. However, since the cross-sectional shape measuring apparatus used for the welding apparatus must be used by arranging sensors in the very vicinity of the welded portion, it is exposed to a high temperature during measurement and temperature management is difficult.
Therefore, when using a laser projector incorporating a semiconductor laser generator, the bandpass filter that transmits the region sandwiching the wavelength of the laser beam is set in consideration of the fluctuation of the peak wavelength, so that the transmission wavelength width is narrowed to about 20 nm, for example. In some cases, it is difficult to obtain highly accurate measurement results.
Also, measurement may not be possible if the device temperature does not fall within the usable range, such as during cold start.
[0033]
Therefore, in the cross-sectional shape measuring apparatus of this embodiment, by controlling the temperature of the semiconductor laser generator to be constant, it is possible to narrow the transmission width of the band-pass filter, thereby suppressing the intrusion of noise light and measuring. The accuracy can be further improved. Moreover, it can measure correctly also when environmental temperature is too low.
As shown in FIG. 8, the temperature control system of the laser projector includes a temperature measuring element 52 such as a thermocouple or thermistor attached to a casing 51 of a laser projector incorporating a semiconductor laser generator, and a heat transfer element such as a Peltier element. 56, and a temperature regulator 53 connecting them.
[0034]
The temperature regulator 53 includes a temperature comparison circuit 54 and an applied current adjustment circuit 55, converts the output of the temperature measurement element 52 into a temperature signal, compares it with a target temperature value, and heat-transfers the current value calculated based on the deviation. This is supplied to the element 56.
Since there are delay elements in the temperature control system, it is usually sufficient to adjust the applied current by ON / OFF control, and the control logic is very simple. Note that so-called time-proportional ON / OFF control is adopted, and when the deviation is large, one of ON / OFF is selected. If it is changed proportionally, temperature fluctuation can be suppressed more effectively and highly accurate temperature control can be achieved.
The temperature regulator 53 can be configured by a device having an electronic calculation function such as a microcomputer, and can be incorporated in the CPU board 21 of the controller 2.
[0035]
As shown in FIG. 9, two types of semiconductors A and B having a difference in Peltier effect are alternately connected in series. The terminal T can be connected to a DC power source and used as a thermoelectric cooling element. Such a Peltier element can be switched between heating and cooling by changing the polarity of the current applied to both terminals T. Therefore, when used as the heat transfer element 56, the temperature of the laser projector can be controlled more highly. it can.
[0036]
By stabilizing the output of the laser projector by the above temperature control system, the peak wavelength of the laser beam does not fluctuate as shown in FIG. 10, so the bandwidth of the optical filter charged in the optical sensor 12 is narrowed to about 5 nm. can do.
FIG. 10 shows the wavelength distribution of the laser light emitted from the laser projector on the upper stage, and shows the transmission wavelength region of the band-pass optical filter for transmitting the laser light and blocking external light noise on the lower stage. In the figure, the state without temperature control is indicated by a dotted line, and the result of introducing the temperature control system is indicated by a solid line.
[0037]
Even within the usable temperature range of the semiconductor laser generator, the peak wavelength fluctuates by about 20 nm, so that the bandpass width of about 20 nm is still necessary to transmit this. However, if the temperature management of the laser projector 11 is performed, the peak wavelength does not fluctuate. Therefore, it is sufficient to have a transmission width that can cover the spread of the laser light, for example, a transmission width of about 5 nm.
For this reason, the absolute amount of disturbance light transmitted through the filter is reduced, the ratio of the laser light in the transmitted light is increased, and the SN ratio is greatly improved. Therefore, even if the threshold value for determining the contour line is set strictly, erroneous detection is reduced, so that a sharper contour line is generated in cooperation with a mechanism that adjusts the amount of incident light based on the amount of light received by the CCD sensor. By detecting this, it becomes possible to perform highly accurate shape measurement.
[0038]
Further, even when the engine is started in a state where the outside air temperature is extremely low, the temperature of the laser projector 11 is managed, so that measurement is not disabled.
It is preferable to install the temperature detection end and the heat transfer element as close to the semiconductor laser generator as possible so that they act directly.
Even when a conventional laser projector is used, a temperature control system can be easily configured by adding these elements.
It goes without saying that a certain accuracy improvement effect can be obtained even if the temperature adjustment system of the laser projector is used independently of the incident light amount adjustment mechanism.
[0039]
The cross-sectional shape measuring apparatus of the present embodiment uses the measurement result obtained in the previous scanning so that the incident light amount of the sensor is suppressed in a portion where the reflected light is bright and the incident light amount is increased in a portion where the reflected light is dark. Therefore, the size of the acquired light spot image does not change regardless of the change in the properties of the target portion, the contour line can be accurately defined, and highly accurate cross-sectional shape measurement can be performed.
Also, by storing and using the conversion table and calculation formula used to adjust the amount of incident light as software in a storage device, it is possible to easily change the table and formula. It is possible to easily cope with the case of correcting a table or the like.
[0040]
In the description of the above embodiment, the adjustment value is calculated using the measurement data obtained in the previous scanning. However, the past measurement data may be regarded as having not changed from the current measurement. Needless to say, it does not have to be the latest data.
In addition, the cross-sectional shape measuring apparatus of the present embodiment can be easily configured by adding a controller, a temperature adjustment system, and the like to the conventional copying welding apparatus.
Although the case where a red laser is used has been described here, it goes without saying that rays of other regions such as infrared rays may be used.
[0041]
【The invention's effect】
As described above, the cross-sectional shape measuring apparatus of the present invention is applied to a beam scan type laser sensor provided close to a welded part such as an automatic scanning welding apparatus, thereby reflecting the incident light on the sensor due to a change in the condition of the measurement target part. Even when the light fluctuates, the welding shape can be measured with high accuracy, and when the semiconductor laser generating element is used, the shape can be measured with high accuracy.
[Brief description of the drawings]
FIG. 1 is a block diagram of a cross-sectional shape measuring apparatus in an embodiment of the present invention.
FIG. 2 is a conceptual diagram showing a configuration of a sensor head used in this embodiment.
FIG. 3 is a diagram illustrating an example of an image composition result in the present embodiment.
FIG. 4 is a distribution diagram showing an example of a change in received light amount in the laser scanning direction in the present embodiment.
FIG. 5 is a diagram illustrating an example of a conversion table used for obtaining a control amount in the present embodiment.
FIG. 6 is a flowchart illustrating an incident light amount control procedure in the present embodiment.
FIG. 7 is a diagram for explaining the relationship between image scanning and control amount determination timing;
FIG. 8 is a block diagram of a laser projector temperature control system used in the present embodiment.
FIG. 9 is a conceptual diagram illustrating the structure of a Peltier element used as a heat transfer element.
10 is a diagram for explaining the effect of temperature control in FIG. 8; FIG.
[Explanation of symbols]
1 Sensor head of laser sensor
2 Controller
3 Display
11 Laser projector
12 One-dimensional optical sensor
13 Scanning mirror
4 Measurement object
14 Condensing optical system
15 Oscillating shaft
21 CPU board
22 Image input board
23 Interface board
24 buses
51 Laser projector housing
52 Temperature measuring element
53 Temperature controller
54 Temperature comparison circuit
55 Applied current switching circuit
56 Heat transfer element

Claims (6)

A laser radiation device, a one-dimensional optical sensor, and a scanning mechanism that guides the laser light from the laser radiation device to a target, scans the laser light in one direction, and reflects the laser light reflected from the target to the one-dimensional optical sensor. And an incident light amount adjuster for adjusting an incident light amount by adjusting an output of the laser radiation device and an exposure condition of the one-dimensional photosensor, and the incident light amount adjuster includes an operation amount for the adjustment, and A one-dimensional optical sensor detects when the same irradiation direction has been previously linked to the laser beam irradiation direction during scanning by the scanning mechanism , with a storage device storing the functional relationship between the incident light amounts the received light amount of the entire said one-dimensional optical sensor as the brightness evaluation value, the adjustment value the brightness evaluation value over one cycle scanning for adjusting the amount of incident light so as to approach a predetermined target value The column was prepared by using the functional relationship, the cross-sectional shape measurement apparatus and adjusting the amount of incident light based on the column of the adjustment value. 2. The cross-sectional shape according to claim 1, wherein the received light amount serving as a reference for adjusting the incident light amount is a detected light amount when a laser light irradiation direction during the scanning is the same direction in the previous scanning. Measuring device. 3. The cross section according to claim 1, wherein the scanning mechanism is a scanning mirror that reciprocates about a swing axis, and includes an angle sensor that detects a swing angle and estimates a laser beam radiation direction. Shape measuring device. The cross-sectional shape measuring apparatus according to claim 2 or 3, wherein the adjustment of the amount of incident light is performed in both the forward path and the return path of the swing of the scanning mirror. The amount of light received by the one-dimensional photosensor, which serves as a reference for adjusting the amount of incident light, is the maximum amount of light detected by any one of the light-receiving elements constituting the sensor , instead of the amount of light received by the entire one-dimensional photosensor. The cross-sectional shape measuring apparatus according to any one of claims 1 to 4, wherein 6. The cross-sectional shape measuring apparatus according to claim 1, wherein the functional relationship is stored in the storage device in the form of a conversion table.

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