JP2009257857A - Melting temperature determination apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a melting temperature determination apparatus for reliably determining whether a region to which a solder is supplied reaches a melting temperature of the solder. <P>SOLUTION: The melting temperature determination apparatus includes: a camera 2 for capturing an image of preliminary solder section Z previously formed in the region Y to which the solder is supplied; a soldering iron 3 for heating the region Y; an extraction means 11 for extracting an area W in which the preliminary solder section Z exists from the image sequentially captured by the camera 2; an intensity value calculating means 12 for calculating an intensity value of each pixel in the extracted area W; and a determination means 13 for determining whether the region Y heated by the soldering iron 3 reaches the melting temperature of the solder based on a change in the intensity value of each pixel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a melting temperature determination device that determines whether or not a portion for supplying solder has reached a melting temperature of solder.

  For example, as shown in Patent Document 1, in an automatic soldering apparatus using a soldering iron, the temperature of the part reaches the solder supply temperature by bringing the soldering iron into contact with the part to which the solder is supplied for a predetermined time. As solder is supplied.

In such an automatic soldering apparatus, the moment when the tip of the soldering iron touches the part is detected by a contact detector, and a time set in advance from the detection timing is set as a preheating time, and solder is supplied after this time has elapsed. The time until soldering is completed is managed.
Japanese Patent Laid-Open No. 54-23056

  However, when the timing of supplying solder is managed by time as in a conventional automatic soldering apparatus, there are the following problems.

  First, it is assumed that the solder supply temperature has reached the solder supply temperature due to the elapse of a preset preheating time, but in the case of insufficient heating, the supply temperature is not reached. End preheating.

  In addition to solder scraps, solder-like stains due to oxides or the like may adhere to the soldering iron tip. Such dirt is gradually laminated to cause deterioration of the tip, and becomes a factor that hinders temperature rise of the tip. Therefore, depending on the state of the tip, the heat transfer coefficient between the tip and the solder supply site may be reduced, and heating may be insufficient even during the same preheating time.

  In particular, lead-free solder (solder that does not contain lead), which has become the mainstream in recent years, has a melting temperature of about 220 ° C., which is higher than that of conventional eutectic solder (melting point: 183 ° C.).

  Secondly, in order to eliminate such heating shortage, it may be possible to change the set time according to the state of the tip, but it is difficult to evaluate the state of the tip. Even if the state of the tip can be evaluated, it is complicated to change the set time each time according to this state, and the work efficiency of the solder may be lowered.

  In view of the above circumstances, an object of the present invention is to provide a melting temperature determination device that can reliably determine whether or not a portion to which solder is supplied has reached the melting temperature of the solder.

  According to a first aspect of the present invention, there is provided an apparatus for determining a melting temperature, comprising: an imaging unit that obtains an image of a preliminary solder portion that is formed in advance on a part to which solder is supplied; a heating unit that heats the part; Extraction means for extracting an area where the spare solder portion exists, luminance value calculation means for calculating a luminance value of each pixel in the area extracted by the extraction means, and for each pixel calculated by the luminance value calculation means And determining means for determining whether or not the portion heated by the heating means has reached the melting temperature of the solder based on a change in luminance value.

  According to the melting temperature determination apparatus of the first aspect of the present invention, whether or not the part to which the solder is supplied has reached the melting temperature of the solder by the heating of the heating unit is determined based on the image of the preliminary solder portion formed in advance in the part Judgment. Here, since the surface state of the solder is different between the non-molten state before heating and the molten state after heating, the surface reflection mode is different. For example, in the lead-free solder, the surface is satin and the light is diffusely reflected in the non-molten state, whereas the surface is a mirror surface and the light is totally reflected in the molten state. Such a surface reflection mode is characteristic in the luminance value in the region of the preliminary solder portion. Therefore, in the melting temperature determination device of the present invention, it is possible to determine whether or not the preliminary solder portion has reached the melting temperature based on the change in luminance value in the preliminary solder portion region, thereby supplying solder. It can be reliably determined whether or not the part has reached the melting temperature of the solder.

  According to a second aspect of the present invention, there is provided the melting temperature determination apparatus according to the first aspect, wherein the determination means has a size of an area of the first luminance portion where the luminance value in the region is a value within a first predetermined range. It is characterized by determining whether or not the part has reached the melting temperature of the solder due to the change.

  According to the melting temperature determination device of the second aspect of the invention, the solder value is determined based on the change in the area of the first luminance portion in which the luminance value falls within the first predetermined range among the luminance values in the preliminary solder portion region. It is determined whether or not has reached the melting temperature. Here, the first predetermined range that defines the first luminance portion can be a range in which a change in luminance value appears remarkably between the unmelted state and the molten state of the preliminary solder portion. Thereby, since it can be determined that the preliminary solder portion is in a molten state based on a change in the size of the area of the first luminance portion, it is easy for the portion to reach the melting temperature of the solder. And it can be determined with certain certainty.

  According to a third aspect of the present invention, there is provided the melting temperature determination apparatus according to the first or second aspect, wherein the determination means calculates a difference between the previous value and the current value of the luminance value calculated by the luminance value calculation means. A difference luminance value is sequentially calculated, and it is determined based on a change in the difference luminance value whether or not the part has reached the melting temperature of the solder.

  According to the melting temperature determination device of the third invention, it is determined whether or not the solder has reached the melting temperature based on a change in the difference luminance value between the previous value and the current value of the luminance value in the preliminary solder portion region. The Here, the luminance value corresponding to the change of the pre-solder part from the non-molten state to the molten state becomes characteristic in the temporal change of the luminance value before and after that. Therefore, based on the change in the difference luminance value in the area of the preliminary solder portion, whether or not the preliminary solder portion has reached the melting temperature has been determined, thereby determining whether the portion that supplies the solder has reached the melting temperature of the solder. It is possible to reliably determine whether or not.

  According to a fourth aspect of the present invention, there is provided the melting temperature determination apparatus according to the third aspect of the present invention, wherein the determination means has a large area of a second high-luminance portion where the difference luminance value in the region is a second predetermined range value. It is characterized in that it is determined whether or not the portion has reached the melting temperature of the solder according to the change in the length.

  According to the melting temperature determination apparatus of the fourth aspect of the invention, based on a change in the area of the second luminance portion in which the difference luminance value is within the second predetermined range among the difference luminance values in the preliminary solder portion region. It is then determined whether the solder has reached the melting temperature. Here, the second predetermined range that defines the second luminance portion can be a range in which a change in the difference luminance value appears remarkably between the non-molten state and the molten state of the preliminary solder portion. As a result, it is possible to determine that the preliminary solder portion is in a molten state based on a change in the size of the area of the second luminance portion, so that it is easy for the portion to reach the melting temperature of the solder. And it can be determined with certain certainty.

  An automatic soldering apparatus according to a fifth aspect of the invention includes the melting temperature determination apparatus according to any one of the first to fourth aspects. According to the automatic soldering apparatus of the fifth aspect of the present invention, since the solder can be automatically supplied based on the determination result of the melting temperature determination apparatus, it is suitable as an object to which the melting temperature determination apparatus is applied.

  A melting temperature determination apparatus as one embodiment of the present invention will be described with reference to FIGS.

  A melting temperature determination apparatus 1 shown in FIG. 1 is mounted on, for example, an automatic soldering apparatus, and determines whether or not a portion for supplying solder has reached a temperature for supplying solder by preheating.

  The melting temperature determination apparatus 1 heats the preliminary solder portion Z, and a camera 2 as an imaging unit that obtains an image of the preliminary solder portion Z made of lead-free solder formed in advance on a portion Y for supplying solder on the substrate X. The soldering iron 3 as the heating means, the ring illumination 4 as the illuminating means for illuminating the preliminary solder portion Z, and the image processing of the image obtained by the camera 2 and the portion Y from the image processed image are brought to the melting temperature of the solder. And a controller 10 that executes a determination process for determining whether or not it has been reached. The melting temperature determination device 1 is connected to a solder supply device 5 that supplies solder based on the result of determination processing by the controller 10.

  The camera 2 is a monochrome camera and is installed so as to include the preliminary solder portion Z in its imaging range, starts imaging in response to a control signal from the controller 10, and outputs the captured image data to the controller 10. Since the camera 2 only needs to obtain a grayscale image from the captured image, a color camera such as a CCD camera can be used.

  The soldering iron 3 has a tip 32 at the tip of a cylindrical outer mantle 31 attached to a work arm or the like of an automatic soldering apparatus (not shown). In addition, an electric heater connected to the controller 10 is built in the outer jacket 31. The electric heater operates in response to a control signal from the controller 10 and heats the tip 32.

  The ring illumination 4 has a central opening 41 coaxial with the imaging axis of the camera 2 and fixed to the substrate X by a fixture. The ring illumination 4 is connected to the controller 10 and operates based on a control signal from the controller 10 to illuminate the preliminary solder portion Z with appropriate illuminance.

  The solder supply device 5 includes a solder supply unit 51 that feeds thread-shaped lead-free solder wound around a reel in a necessary amount, and a guide unit 52 that sends out the solder supplied from the solder supply unit 51 toward the site Y. . The solder supply unit 51 supplies solder to the guide unit 52 at an appropriate timing and speed based on a control signal from the controller 10.

  The controller 10 is constituted by a microcomputer or the like, and includes an extraction unit 11, a luminance value calculation unit 12, a determination unit 13, an illumination control unit 14, and a heating control unit 15.

  The extraction unit 11 executes a process of extracting a region where the preliminary solder portion Z exists from images sequentially obtained by the camera 2. The luminance value calculation unit 12 executes a process for calculating the luminance value of each pixel in the region extracted by the extraction unit 11. The determination means 13 mainly determines whether or not the portion Y has been heated by the soldering iron 3 to reach the melting temperature of the solder based on the change in the luminance value of each pixel calculated by the luminance value calculation means 12. Execute the process.

  The illumination control means 14 performs a process of generating and outputting a control signal that specifies ON / OFF of the ring illumination 4 and its illuminance. The heating control means 15 generates and outputs a control signal that specifies the heating amount or temperature of the electric heater of the soldering iron 3.

  The units 11 to 15 constituting the controller 10 are configured by hardware such as a CPU, a ROM, and a RAM, and these units may be configured by common hardware. A part or all of them may be configured by different hardware.

  Next, with reference to the flowchart shown in FIG. 2, the process of the controller 10 in the melting temperature determination apparatus 1 of this embodiment is demonstrated.

  First, the controller 10 determines whether or not the board X to be soldered is set at a predetermined position (STEP 1). Therefore, the position of the board | substrate X is detected with the detector which is not shown in figure, and it determines based on the detection result.

  Then, when the substrate X is set (YES in STEP 1), the controller 10 turns on the ring illumination 4 via the illumination control means 14 (STEP 2). On the other hand, when the board | substrate X is not set (it is NO at STEP1), it waits until the board | substrate X is set through the said detector.

  When the substrate X is set and the ring illumination 4 is turned on (STEP 2), the controller 10 acquires an image output from the camera 2 as a reference image (STEP 3).

  At this time, the solder iron 3 heated via the heating control means 15 stands by just above the point where it does not come into contact with the preliminary solder portion Z. Specifically, a reference image as shown in FIG. To be acquired. In the reference image of FIG. 3A, the board X and the preliminary solder portion Z in which solder is applied in advance are imaged.

  The reference image is an image showing a state before heating by the soldering iron 3, and is a reference image for observing subsequent image changes.

  Next, the controller 10 extracts the region W including the preliminary solder portion Z from the acquired reference image by the extraction unit 11 (STEP 4). Specifically, a designated region (a region in which the position and the spread are designated) in the reference image designated by the user in advance is extracted as a region W including the spare solder portion Z. For example, as shown in FIG. 3B, a region W including the preliminary solder portion Z is extracted from the reference image shown in FIG. Here, the area W is designated by the user as an area that is substantially the same shape or slightly wider than the portion Y for supplying solder.

  Next, the controller 10 calculates the luminance value of each pixel with respect to the region W of the reference image by the luminance value calculation means 12 (STEP 5), and then the luminance value of each pixel becomes a value within the first predetermined range. One luminance portion P is extracted (STEP 6). Here, the first luminance portion is obtained by removing the super high luminance portion (for example, the portion of 95% or more of the luminance value gradation) in the region W, and the luminance value is 30% from the high luminance value by the P tile method. Is extracted as a region. For example, with respect to the region W shown in FIG. 3B, the first luminance portion P having a luminance value within the first predetermined range in the preliminary solder portion Z as shown by the oblique lines in FIG. Extracted. Then, the controller 10 calculates the luminance value T obtained by the P tile method at this time, and holds it in an internal memory (not shown) or the like (STEP 7).

  In the present embodiment, when extracting the first luminance portion P, preprocessing excluding ultra-high luminance is performed in order to remove noise in the image, and then a region having a predetermined luminance value is defined as the first luminance portion P. However, it may be extracted as a region where the gradation of the luminance value is, for example, 30 to 35% without performing preprocessing.

  Next, the controller 10 causes the soldering iron 3 that has been waiting immediately above the preliminary solder portion Z to contact the preliminary solder portion Z by using a work arm (not shown), and starts heating the preliminary solder portion Z (STEP 8). At the same time, the controller 10 sequentially acquires images output from the camera 2 (STEP 9). The image acquired here is a continuous image captured at a constant period.

  Then, the controller 10 uses the luminance value calculation means 12 to calculate the luminance value of each pixel in the portion corresponding to the region P of the first luminance portion of the reference image in each image acquired in STEP 9 (STEP 10).

  Next, the controller 10 uses the luminance value T (see STEP 7) for the luminance value of each pixel calculated in STEP 10 by the determination unit 13, and the first luminance in which the luminance value of each pixel falls within the first predetermined range. The part P is extracted (STEP 11).

  Subsequently, the determination unit 13 of the controller 10 normalizes the size of the area of the first luminance part P in the image sequentially acquired in STEP 9 using the first luminance part P of the reference image, and normalizes the first luminance part. It is determined whether the area ratio (area ratio) of P is equal to or greater than a threshold value (STEP 12).

  Here, the size of the area of the first luminance value P is such that when the portion Y is heated by the soldering iron 3 and the temperature of the preliminary solder portion Z formed there rises, the preliminary solder portion Z has a luminance in the captured image. The value drops. That is, the pre-solder portion Z made of lead-free solder has a satin surface before heating, and the light irradiated on the surface from the ring illumination 4 is irregularly reflected and detected as a high-luminance portion as a whole. On the other hand, when melting starts by heating, the surface changes to a mirror surface, and the brightness value as a whole decreases. As a result, the size of the area of the first luminance value P decreases as the heating time elapses, but the size of the area is normalized by the first luminance portion P of the reference image (a negative change is made). The area ratio of the first luminance value P increases as the heating time elapses.

  Then, by determining whether or not the normalized area ratio of the first luminance portion P is equal to or greater than a threshold corresponding to the melted state, the part Y for supplying the solder reaches the temperature for melting the solder. It can be determined whether or not.

  Specifically, as schematically shown in FIG. 4 (a), the area ratio of the normalized first luminance portion P is increased by being heated by the soldering iron 3 at time t0, and in a molten state at time t1. Thus, after time t2, there is almost no change regardless of the heating time. By setting the area ratio of the first luminance portion P corresponding to the time t1 as the threshold value, it is possible to detect that the part Y has first reached the melting temperature of the solder.

  Actually, the normalized area ratio of the first luminance portion P shown in FIG. 3C is shown in FIG. The normalized area ratio of the first luminance portion P increases after time t0 when heating is started and is in a molten state at time t1. In FIG. 5A, the area ratio of the first luminance portion P corresponding to time t1 is set as the threshold value P1, and it is detected that the part Y has first reached the melting temperature of the solder.

  Next, when the normalized area ratio of the first luminance portion P is equal to or greater than the threshold value corresponding to the melted state (YES in STEP 12), the determination unit 13 of the controller 10 sequentially acquires in a constant cycle in STEP 9. In the obtained image, the difference in luminance value of the region W between adjacent images is calculated as a difference luminance value (STEP 13).

  Next, the controller 10 extracts the second luminance portion Q in which the difference luminance value calculated in STEP 13 falls within the second predetermined range by the determination unit 13 (STEP 14). Here, the second predetermined range that defines the second luminance portion Q is the size of the difference luminance value in which the difference luminance value appears significantly between the unmelted state and the molten state of the preliminary solder portion Z. Note that a difference in the first luminance part P between successive images may be simply extracted as the second luminance part Q.

  Subsequently, the determination unit 13 of the controller 10 normalizes the size of the area of the second luminance portion Q in the image sequentially acquired in STEP 14 with the first luminance portion P of the reference image, and normalizes the normalized second luminance portion Q. It is determined whether the area ratio (area ratio) is equal to or less than a threshold value (STEP 15).

  Here, the second luminance portion Q is a negative value because it corresponds to the difference between images before and after the first luminance portion P, and the size of the area is the area of the first luminance portion P between the preceding and following images. Is proportional to the difference. The area of the second luminance part Q is normalized by normalizing the magnitude of the change in the area with the first luminance part P of the reference image (converting the negative change into a positive value to obtain the ratio of the area change with respect to the reference image). The magnitude of increases as the heating time elapses and then decreases.

  Then, by determining whether or not the area ratio of the normalized second luminance portion Q is equal to or less than the threshold value corresponding to the molten state, the portion Y to which the solder is secondarily supplied reaches the temperature for melting the solder. It can be determined whether or not it has been reached.

  Specifically, as schematically shown in FIG. 4B, the normalized area ratio of the second luminance portion Q rises by being heated by the soldering iron 3 at time t0, and is in a molten state at time t1. The peak value is reached and falls after time t2. Therefore, by detecting that the area ratio of the second luminance portion Q becomes 0 or equal to the value after the time t1 (the luminance value no longer changes), the portion Y is secondarily melted by the solder. It can be detected that the temperature has been reached.

  Actually, the difference between the images of the first luminance portion P shown in FIG. 3C between the images is set as the second luminance portion Q, and the second luminance portion Q is normalized and shown in FIG. 5B. The normalized area ratio of the second luminance portion Q increases after time t0 when heating is started, and reaches a peak value at time t1. In FIG. 5B, the threshold value is set to 0, and it is secondarily detected that the part Y has reached the melting temperature of the solder at time t2 when the area ratio of the second luminance portion Q is 0 after time t1. is doing.

  Next, when the normalized area ratio of the second luminance portion Q is equal to or less than the threshold value corresponding to the melted state (YES in STEP 15), the determination unit 13 of the controller 10 melts the part Y that supplies the solder. It is determined that the temperature has been reached (STEP 16), and solder is supplied to the portion Y by the solder supply device 5 (STEP 17).

  On the other hand, the determination means 13 of the controller 10 determines that the normalized area ratio of the first luminance portion P is not equal to or greater than the threshold corresponding to the melted state (NO in STEP 12) or the normalized second luminance portion Q. If the area ratio is not less than or equal to the threshold corresponding to the melted state (NO in STEP 15), the process returns to STEP 9 and the determination process of STEP 9 and below is repeatedly performed based on the newly acquired image.

  The above is the process for determining whether or not the part Y executed in the controller 10 has reached the melting temperature of the solder. In such a process, the portion Y is brought to the melting temperature of the solder on the basis of the change in the first luminance portion P and the second luminance portion Q in which the luminance value changes significantly between the non-molten state and the molten state of the preliminary solder portion Z. Whether or not it has been reached can be reliably determined.

  In the present embodiment, when both the first luminance portion P and the second luminance portion Q exhibit the feature that the preliminary solder portion Z is in a molten state, the portion Y has reached the melting temperature of the solder. However, the present invention is not limited to this, and when one of the first luminance portion P and the second luminance portion Q shows a characteristic that the preliminary solder portion Z is in a molten state, the portion Y reaches the melting temperature of the solder. It may be determined that

  In the present embodiment, the first luminance portion P and the second luminance portion Q are extracted as predetermined luminance ranges. However, the present invention is not limited to this, and the acquired image may be binarized. In this case, a graph equivalent to FIGS. 4A and 4B can be obtained by normalizing the binarized images with the region W of the reference image and the first luminance portion P of the reference image.

  Furthermore, in the present embodiment, the case where the melting temperature determination device 1 is mounted on the automatic soldering device has been described. However, the present invention is not limited to this, and is configured as an independent device that assists the user performing the soldering operation. May be.

  In this embodiment, the case where lead-free solder is applied to the preliminary solder portion Z has been described. However, the solder and the preliminary solder portion Z may be used as eutectic solder other than lead-free solder. In this case, it is necessary to suitably set the resolution of the camera 2 in order to determine the unmelted state and the molten state of the solder.

  Furthermore, in the present embodiment, the ring illumination 4 is provided, and the change in the surface state in the non-molten state and the molten state of the preliminary solder portion Z is remarkable, but by suitably setting the resolution of the camera 2, The ring illumination 4 may be omitted.

The figure which shows the whole structure of the melting temperature determination apparatus of this embodiment. The flowchart which shows the process in the controller of this embodiment. Explanatory drawing which shows the example at the time of performing the process of FIG. 2 on an actual image. Explanatory drawing which shows the processing content of FIG. Explanatory drawing which shows the processing content of FIG. 2 in the image of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Melting temperature determination apparatus, 2 ... Camera, 3 ... Solder iron, 4 ... Ring illumination, 5 ... Solder supply apparatus, 10 ... Controller, 11 ... Extraction means, 12 ... Luminance value calculation means, 13 ... Determination means, 14 ... Illumination control means, 15... Heating control means, X... Substrate, Y.

Claims (5)

An image pickup means for obtaining an image of a preliminary solder portion formed in advance on a portion for supplying solder;
Heating means for heating the part;
An extraction means for extracting an area where the preliminary solder portion exists from images sequentially obtained by the imaging means;
Luminance value calculating means for calculating the luminance value of each pixel in the region extracted by the extracting means;
And determining means for determining whether or not the portion heated by the heating means has reached the melting temperature of the solder based on a change in the brightness value of each pixel calculated by the brightness value calculating means. A melting temperature determination device. In the melting temperature determination apparatus according to claim 1,
The determination means determines whether or not the part has reached a melting temperature of the solder due to a change in the size of the area of the first luminance part where the luminance value in the region is a value in a first predetermined range. An apparatus for determining a melting temperature. In the melting temperature determination apparatus according to claim 1 or 2,
The determination unit sequentially calculates a difference between the previous value and the current value of the luminance value calculated by the luminance value calculation unit as a difference luminance value, and based on a change in the difference luminance value, the part is soldered. A melting temperature determining apparatus for determining whether or not a melting temperature has been reached. In the melting temperature determination apparatus according to claim 3,
The determination unit determines whether or not the part has reached the melting temperature of the solder based on a change in the size of the area of the second luminance part where the difference luminance value in the region is a value in a second predetermined range. An apparatus for determining a melting temperature.   An automatic soldering apparatus comprising the melting temperature determination apparatus according to any one of claims 1 to 4.