JP2000196298A - Substrate mark recognition mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the accuracy of positioning a substrate in a component packaging apparatus. SOLUTION: An illuminator 22 casts light on a mark 4a for positioning provided on the surface of a substrate 4. An image pickup camera 21 picks up an image of the position of the mark 4a and recognizes it on the basis of a reflected light from the mark 4a of the light cast from the illuminator 22. A moving mechanism 23 for moving lamps 22a and 22b of the illuminator 22 is provided, and constitution is so made that at least either an angle θ formed by the surface of the substrate 4 at the position of the mark 4a and the illuminator 22 or a length of the distance between the mark 4a and the illuminator 22 can be changed. Even when the shape of the surface of the mark 4a is changed and no stable reflected light is obtained in a prescribed direction, accordingly, setting is made so that an increased quantity of reflected light can be obtained, by the control of positions of the lamps 22a and 22b by the moving mechanism 23. Thus, the probability of recognition of the positioning mark 4a can be enhanced in excellent contrast.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a surface mounting apparatus for mounting a chip component such as an IC on a printed wiring board, printing cream solder, or applying an adhesive, and is used on a printed circuit board. The present invention relates to a board mark recognizing mechanism for taking an image of a positioning mark by an imaging camera and recognizing a position of the board.

[0002]

2. Description of the Related Art In recent years, as chip components and the like have been miniaturized, it has been required to improve the position recognition accuracy of a printed wiring board in order to increase the mounting density of those components.

FIG. 8 shows a conventional board mark recognition mechanism 2 mounted on a component mounting head 1. The component mounting head 1 is first fixed to a lower portion of an X slider 31 of an XY moving mechanism 3. .

[0004] The X slider 31 has an X guide rail 31a.
A ball screw (not shown) is driven by an X-axis motor 31b provided at one end of the slider, and is slidable in the X direction. The X guide rail 31a itself is attached to the Y slider 32.

[0005] The Y slider 32 is configured to be capable of being positioned in the Y direction along a Y guide rail 33a provided on the fixed portion 33 by the rotational driving of a ball screw 32a.

Accordingly, the Y slider 32 is slidably provided in the Y direction, and the X slider 31 is slidably provided in the X direction. The component mounting head 1 can be positioned at any position in the XY direction. Although not shown, the component mounting head 1 itself is configured to be rotatable in a horizontal (angle φ) direction around a Z-axis direction perpendicular to the X-Y direction by motor control. The component mounting head 1 is provided with a mounting tool, for example, a suction nozzle 1a, which is slidably mounted in a vertical direction.

Therefore, for example, circular positioning marks 4a are provided at a plurality of positions (for example, two positions) on the upper surface of the printed wiring board 4 carried by a carrying table (not shown), and the marks 4a are used as a board mark recognition mechanism. The image is picked up by the second imaging camera 21, and the imaging signal is supplied to the image processing device 5 to determine the center position of the mark 4a on the two-dimensional coordinates, that is, the center position of the mark 4a.

[0008] The image processing apparatus 5 also includes a predetermined substrate 4
The position error from the reference position is detected by pattern recognition,
Since the supply is supplied to the control device 6, the control device 6 controls the movement of the component mounting head 1 in the X-Y-φ direction so that the position error becomes zero.

Therefore, as shown in FIGS. 9 and 10 in an enlarged manner, the imaging camera 21 and the lighting fixture 22 are integrally fixed to the component mounting head 1, and the imaging direction of the imaging camera 21 is Is configured to be perpendicular to the surface of the transfer table on which is mounted. In the lighting fixture 22, a plurality of lamps 22a and 22b such as light emitting diodes (LEDs) are provided at substantially equal intervals on a circumference having a radius R around the optical axis Z of the imaging camera 21. 4 so as to emit light in the direction of the mark 4a.

The imaging camera 21 captures an image by receiving the reflected light from the mark 4a. Whether or not a clear image can be obtained depends on the reflected light from the mark 4a and the surrounding background area surrounding the mark 4a. Based on the contrast formed between the reflected light.

The printed wiring board 4 is made of a film-based flexible printed wiring board made of polyester or the like in addition to a board made of a relatively hard insulating material such as a bake plate or an epoxy plate. It has come to be used.

This flexible substrate has a small thickness and is easily bent. Even if the flexible substrate is mounted on a pallet jig such as a motherboard, the surface of the substrate is deformed. Not necessarily. Therefore, the mark 4a surface on the flexible substrate also has a shape in which the surface is uneven, distorted or bent.

Therefore, as shown in FIG. 11, for example, when the surface of the mark 4a is rounded and deformed in a convex shape, the direction of the entire surface may not always be directed to the imaging direction axis Z. In such a case, the reflected light axis from the mark 4a by the lamps 22a and 22b arranged in a ring shape with a radius R around the imaging direction axis Z is shifted and deviates from the imaging direction axis Z direction.

[0014]

As described above, the mark on the surface of the flexible substrate is easily deformed, and the reflection optical axis of the light emitted from the lighting device is deviated. There was a drawback that an image could not be obtained.

Further, since the surface of the substrate made of a resin film such as polyester has a relatively large light reflection coefficient unlike a bake plate or the like, a large difference is obtained between the amount of light reflected from the mark surface by a copper foil or the like. It is difficult to obtain a good contrast.

Therefore, if the surface of the substrate or the mark is deformed and the reflected optical axis is deviated, a sufficient amount of reflected light cannot be obtained from the mark, the contrast is reduced, and the mark is difficult to identify. . Therefore, mark identification failure
Immediately leading to a decrease in the operation rate of the component mounting apparatus, improvement has been demanded.

[0017]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and a first invention is a lighting device for irradiating light to a positioning mark provided on a substrate surface. And a substrate mark recognition mechanism having an imaging camera that receives the reflected light of the light emitted from the illuminator from the mark and captures the mark, wherein the substrate surface at the position where the mark is provided, the illuminator, Moving means for moving the illuminating device such that at least one of the angle between the mark and the distance between the mark and the illuminating device changes.

As described above, in the first aspect of the present invention, the moving means is provided, and the angle between the substrate surface at the position where the mark is provided and the lighting device or the distance between the mark and the lighting device changes. Moving the illuminator as described above, the amount of reflected light from the mark supplied to the imaging camera can be increased in accordance with the deformation of the mark surface, so that mark recognition with good contrast can be performed. it can.

According to a second aspect of the present invention, there is provided an illuminator for irradiating light to a positioning mark also provided on a substrate surface, and receiving the reflected light of the light radiated from the illuminator from the mark, forming the mark on In the board mark recognition mechanism having an imaging camera for photographing, the illuminator includes a plurality of lamps, and is arranged such that the angle between the board surface at the position where the mark is provided and each of the lamps is different. It is characterized by.

As described above, according to the second invention, since the plurality of lamps are provided so that the angle between the substrate surface at the position where the mark is provided and the lamp is different, even if the mark surface is deformed, the imaging camera can be used. It is possible to maintain the amount of light reflected toward the target, and to recognize the mark with good contrast.

According to a third aspect of the present invention, there is provided an illuminator for irradiating light to a positioning mark similarly provided on a substrate surface, and receiving the reflected light of the light radiated from the illuminator from the mark to form the mark. In a substrate mark recognition mechanism having an imaging camera for taking an image, a moving means for moving the illumination device so that an angle between the substrate surface at the position where the mark is provided and the illumination device changes, and A threshold setting circuit that sets a level of a preset ratio as a reference threshold with respect to a peak value of an image signal to be captured,
A reference threshold set in advance by the threshold setting circuit and a peak value of an image signal of a mark separately imaged by the imaging camera are calculated, and a threshold based on the predetermined ratio is calculated. A control circuit for controlling the moving means so that a difference from the reference threshold is minimized.

As described above, the third aspect of the present invention includes the control circuit, and sets the level of a predetermined ratio with respect to the peak value of the image signal as a reference threshold value, and sets the peak value of the image signal of a separately captured mark. For the value, a threshold based on the preset ratio is calculated, and the moving means is controlled so that the difference between the calculated threshold and the reference threshold is minimized. By the adjustment control, a good mark image can always be obtained.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a substrate mark recognition mechanism according to the present invention will be described below in detail with reference to FIGS. The same components as those of the conventional configuration shown in FIG. 8 to FIG. 11 are denoted by the same reference numerals, and detailed description is omitted.

FIG. 1 is a front view showing a first embodiment of a substrate mark recognition mechanism according to the present invention. That is, FIG.
Similarly to the conventional configuration shown in FIG. 9, the lighting fixture 22 itself has a radius R about the imaging direction axis Z of the imaging camera 21.
22a, 22b by a plurality of LEDs on the circumference of
Are arranged.

The illuminator 22 is attached to the component mounting head 1 by a moving mechanism 23 so as to be slidable in the vertical direction (that is, in the imaging direction axis Z of the imaging camera 21). The moving mechanism 23 includes a linear guide 23a, and the lighting fixture 22 is configured to be vertically movable along the linear guide 23a by an actuator 23b formed of a cylinder.

The moving mechanism 23 is provided with a plurality of types of stoppers (not shown) having different lengths. The stoppers having a selected length are brought into contact with the linear guide slider 23c to thereby change the lighting fixture 22. It was configured to be able to stop at an arbitrary height H.

When imaging and recognizing the positioning mark 4a on the substrate 4 surface, a sufficient amount of reflected light is supplied from the mark 4a surface to the imaging camera 21 and the mark 4a
It is necessary that a good relative ratio, that is, a contrast, be obtained between the amount of light reflected from a and the amount of light reflected from the surface of the substrate 4 as its background.

The contrast on the picked-up image depends on the relative position between the surface of the substrate 4 and the mark 4a as well as the illuminator 22 and the angle formed by each surface with respect to the picking-up axis Z. 4a is affected by the flatness of the surface.

In any case, in order to ensure necessary and sufficient brightness on the surface of the mark 4a, (1) the distance D between the mark 4a on the substrate surface and the lighting device 22, (2) the lighting device 22
There are two problems, namely, the angle θ of the light radiated toward the mark 4a with respect to the substrate 4 surface.

Therefore, in the first embodiment, as described above, the lighting device 22 is moved by the moving mechanism 23 from the height H0 shown in FIG. 2, for example, to the position of the height H1 shown in FIG. It was configured to obtain.

That is, as shown in FIG. 2, the surface of the mark 4 a on the surface of the substrate 4 is not flat but convex, and the reflection optical axis of the light emitted from the lighting fixture 22 is shifted from the imaging direction axis Z of the imaging camera 21. Even when a sufficient amount of reflected light from the mark 4a cannot be obtained, as shown in FIG.
3 moves the illuminator 22 to the lower height H1, so that the amount of light applied to the mark 4a surface increases, and the imaging camera 21 is sufficient to obtain a good contrast with the background 4 surface. An appropriate amount of reflected light can be obtained.

That is, each lamp 22a,
The distance L between the lamps 22b is constant, and each lamp 22a,
Since the direction of the lamp 22b is also fixed in advance, when the luminaire 22 is moved in a direction in which the height H from the surface of the substrate 4 is lowered, the distance D between the mark 4a and the lamps 22a and 22b becomes shorter, and the distance D to the mark 4a As the amount of irradiation increases,
The light irradiation angle θ of each of the lamps 22a and 22b with respect to the mark 4a also becomes small, and as shown in FIG. 3, the amount of light reflected from the mark 4a toward the imaging camera 21 increases.

As described above, in the first embodiment, since the height H of the lighting fixture 22 can be adjusted and controlled by providing the moving mechanism 23, the surface of the substrate 4 at the position where the mark 4a is provided and the lighting fixture 2 can be controlled.
2, the distance D between the mark 4a and the lighting fixture 22 changes, and the amount of reflected light supplied from the mark 4a to the imaging camera 21 changes according to the surface shape of the mark 4a. Therefore, it is possible to select a situation where a good contrast is obtained and perform mark recognition.

In the above description, a cylinder is used for the actuator 23b of the moving mechanism 23. However, a combination of a servo motor or a pulse motor and a ball screw may be used instead of the cylinder.

In the first embodiment, by changing the height H of the illuminator 22, both the irradiation angle θ to the mark 4a and the length D of the distance between the illuminator 22 and the mark 4a are changed. To adjust the amount of reflected light to the imaging camera 21, but by configuring the moving mechanism 23 so as to mainly change the irradiation angle θ, the imaging camera 21
It is also possible to increase the quantity of reflected light to obtain a good contrast.

That is, the second embodiment of the substrate mark recognizing mechanism according to the present invention, in which the illuminator 22 is moved so as to change the irradiation angle θ and the contrast of the image picked up by the mark 4a can be improved. This will be described with reference to FIGS.

That is, as shown in FIG.
, Lamps 22a and 22b are arranged on both sides around the imaging direction axis Z of the imaging camera 21, and the lamps 22a and 22b
b is slidably formed along each guide groove 221 formed symmetrically in an arc shape, and the irradiation angle θ with respect to the mark 4a is changed (θ1 → θ2, or θ2 → θ1), and the surface shape of the mark 4a is changed. Accordingly, an angle at which the maximum amount of reflected light can be obtained in the direction of the imaging camera 21 can be selected.

The ramps 22a, 2 in the guide groove 221
As shown in FIG. 5A, the movement of the ramp 22
a and 22b are connected to a link mechanism 22c to form a link mechanism 2
2c is driven in an up-down arrow z direction by an actuator such as a servo motor or a pulse motor (not shown), and is moved to a position indicated by a broken line (ramps 22a ', 22b
´). At this time, the upper portion of the link mechanism 22c is formed in an annular shape so that the link mechanism 22c does not hinder the imaging camera 21 from imaging the mark 4a.

In FIG. 5A, the link mechanism 22c is used for moving the ramps 22a and 22b in the guide groove 221. However, as shown in FIG. 5B, a guide rail 22da having a hollow portion is provided outside. A cone (cone) member 22d is arranged, and cam followers (not shown) at the tips of the arms 22aa and 22ba fixed to the ramps 22a and 22b are configured to move along the guide rail 22da.
Is driven in the direction of the up and down arrow z to similarly move to the position indicated by the broken line (the lamps 22a 'and 22b').

In the second embodiment, the lamps 22a and 22b are moved by the moving mechanism 23 so that the irradiation angle θ changes. However, simultaneously with the change of the irradiation angle θ, the first embodiment is performed. The configuration may be such that the height H of the lighting fixture 22 itself is also changed as in the embodiment.

In the embodiment shown in FIG. 4, the lamps of the illuminator 22 are described as having two lamps on the left and right for the sake of description. However, a plurality of lamps are arranged in a ring around the imaging direction axis Z. Needless to say, it can be configured as follows.

As described above, also in the second embodiment, it is set so that the optimum irradiation angle θ is obtained in accordance with the surface condition of the mark 4a to be recognized, and the surface of the mark 4a supplied to the imaging camera 21 is set. Since the amount of light reflected from the mark 4a can be increased, the recognition efficiency of the mark 4a can be increased as in the first embodiment.

Next, in the second embodiment, in the lighting fixture 22, the lamps 22a and 22b made of LEDs or the like are used.
Is moved along the arc-shaped guide groove 221, and the mark 4
Although it was configured to change the irradiation angle θ to irradiate a,
A similar effect can be obtained even if a plurality of lamps are arranged at positions where the irradiation angle θ is variously changed in advance without moving the lamps 22a and 22b and a plurality of layers are arranged on a concentric circumference. it can.

That is, the illumination angle 22
A third embodiment of the substrate mark recognition mechanism according to the present invention, in which a plurality of lamps different from each other are fixedly arranged to improve the contrast of a captured image of the mark 4a, will be described with reference to FIG. .

That is, as shown in FIG.
A plurality of lamps 22a (1 to 4) and 22b (1 to 4) are respectively arranged on a concentric circle centered on the imaging direction axis Z, and the irradiation angles θ to the marks 4a are different in advance (θ1 to θ4). ).

As a result, the surface of the mark 4a is irradiated with at least a plurality of lamps 22a (1-4) and 22b (1-4) having different irradiation angles θ (θ1-θ4) from each other. Even if the surface shape is changed, one of the lamps functions to supply a sufficient amount of light to the imaging camera 21 in response to the change in the surface shape of the mark 4a, and thus the recognition probability of the mark 4a is increased. be able to.

In this embodiment, each lamp 22
a (1 to 4) to 22b (1 to 4) may be turned on, or a switching circuit may be provided so that the amount of reflected light can be obtained most effectively in response to a change in the surface shape of the mark 4a. A configuration may be adopted in which only the lamp is selectively turned on.

Since the recognition of the mark 4a depends on how the bright mark 4a surface is obtained as described above, for example, the moving mechanism 23 in the first embodiment or the like is controlled and the mark 4a is controlled. The position of the illuminator 22 can be controlled so that the optimum amount of reflected light from the camera to the imaging camera 21 is always obtained.

Then, a binarized (black and white) image of the mark 4a captured by the image pickup camera 21 is introduced, and a control circuit 24 for controlling the moving mechanism 23 is added. The embodiment will be described with reference to FIG. That is, FIG. 7A shows a fourth embodiment of the substrate mark recognition mechanism according to the present invention in which a control circuit 24 is added separately to the first embodiment shown in FIGS. First, the reference threshold setting circuit 2 of the control circuit 24
As shown in FIG. 7B, reference numeral 41 denotes the imaging camera 21 in advance.
Of the image signal of the mark 4a obtained by the imaging
A preset ratio, for example, a level of 1/2 with respect to the k value is set as the reference threshold K.

The reference threshold value K is supplied to a comparison circuit 242, and a threshold value calculation circuit 243 is connected to the comparison circuit 242.

As shown in FIG. 7C, the threshold value calculating circuit 243 introduces the image signal of the mark 4a sequentially picked up by the image pickup camera 21, and sets the predetermined ratio (1/2) in the image signal. ) Is calculated and supplied to the comparison circuit 242.

As shown in FIG. 7C, the comparison circuit 242 compares the reference threshold value K with the threshold value Ps of the image signal of the mark 4a newly obtained and picks up the difference ΔP signal. 244.

The control section 244 supplies a control signal to the moving mechanism 23 so that the difference ΔP between the threshold levels is minimized, and the driving mechanism 23 irradiates the illuminator 22 with the distance from the mark 4a or the irradiation of the mark 4a. Since at least one of the angles is feedback-controlled so that the amount of light applied to the mark 4a is increased, the image signal of the mark 4a by the image-capturing camera 21 is set such that the threshold value Ps becomes equal to the reference threshold value K as shown in FIG. It is possible to obtain a mark 4a recognizing image with a good approach and good contrast.

Therefore, conventionally, when the surface of the mark 4a on the substrate 4 is not flat, or even if the surface is
In the case where the laser beam itself is not parallel to the transfer table surface and is inclined, for example, the amount of reflected light from the mark 4a in the direction of the imaging camera 21 is greatly reduced, and good contrast cannot be obtained. According to the embodiment, since the amount of light reflected at the lamp position on the lighting fixture 22 is increased by feedback control, mark recognition can be automated, and at the same time, the mark recognition rate can be improved and the component mounting apparatus can be improved. Operating rate can be improved.

As described above, according to the board mark recognition mechanism of the present invention, even if the shape of the surface of the positioning mark on the printed wiring board is changed, good recognition is performed, and the efficiency of component mounting on the board is reduced. Significant improvements are possible.

[0056]

As described above, according to the present invention, the lamp position of the illuminating device or the light irradiation angle thereof is adjusted and controlled in accordance with the mark surface condition on the substrate surface, or the mark surface condition is changed. Correspondingly, since the lamps are arranged so that a plurality of light irradiation angles can be obtained in advance, the positioning marks can be accurately recognized, the operation rate can be increased, and the substrate marks can be recognized with high accuracy.

According to another aspect of the present invention, a control circuit is provided, and a level of a preset ratio with respect to a peak value of an image signal is set as a reference threshold, and a peak of an image signal of a separately captured mark is set. For the value, a threshold based on the preset ratio is calculated, and the irradiation angle of the lighting fixture is changed so that the difference between the calculated threshold and the reference threshold is minimized. Can be done automatically.

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment of a substrate mark recognition mechanism according to the present invention.

FIG. 2 is a front view showing a position of a lighting device of the mechanism shown in FIG.

FIG. 3 is a front view showing another position of the lighting fixture of the mechanism shown in FIG. 1;

FIG. 4 is a front view showing a second embodiment of the board mark recognition mechanism according to the present invention.

5 (a) is a front view illustrating a lamp moving mechanism of the board mark recognition mechanism shown in FIG. 4, and FIG. 5 (b) is a front view illustrating another lamp moving mechanism also shown in FIG. is there.

FIG. 6 is a main part front view showing a third embodiment of the board mark recognition mechanism according to the present invention.

FIG. 7A is a circuit diagram showing a main part of a fourth embodiment of the board mark recognition mechanism according to the present invention;
7B is an explanatory diagram illustrating a reference threshold set by the reference threshold setting circuit in FIG. 7A, and FIG. 7C is an explanatory diagram illustrating a mark image obtained by the imaging camera in FIG. 7A. , FIG.
FIG. 8D is an explanatory diagram illustrating a mark image obtained by the imaging camera under the control of the control circuit illustrated in FIG.

FIG. 8 is a front view showing a component mounting apparatus employing a conventional board mark recognition mechanism.

9 is an enlarged front view of the board mark recognition mechanism shown in FIG.

10 is a main part front view for explaining irradiation light from a lighting fixture of the mechanism shown in FIG. 8;

11 is a main part front view for explaining irradiation light from a lighting device when the mark surface is deformed in the mechanism shown in FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Component mounting head 2 Board mark recognition mechanism 21 Imaging camera 22 Illumination tool 22a, 22b Lamp 23 Moving mechanism 24 Control circuit 3 XY moving mechanism 4 Board 4a Mark

Claims (5)

[Claims] An illumination device for irradiating light to a positioning mark provided on a substrate surface, an imaging camera for receiving the reflected light of the light emitted from the illumination device from the mark and photographing the mark. In the substrate mark recognition mechanism having at least one of an angle formed between a substrate surface at a position where the mark is provided and the lighting device, or a length of a distance between the mark and the lighting device changes. And a moving means for moving the lighting device so as to perform the operation. 2. The board mark recognizing mechanism according to claim 1, wherein said moving means moves said lighting fixture so as to change a height from said board surface. 3. The substrate mark recognizing mechanism according to claim 1, wherein the moving unit changes a direction of light emitted from the illuminator along with the movement of the illuminator. 4. An illuminator for irradiating light to a positioning mark provided on a substrate surface, an imaging camera for receiving the reflected light of the light emitted from the illuminator from the mark and photographing the mark. Wherein the illuminator includes a plurality of lamps, and is arranged so that the angle between the substrate surface at the position where the mark is provided and each of the lamps is different. Board mark recognition mechanism. 5. An illuminator that irradiates light toward a positioning mark provided on a substrate surface, an imaging camera that receives the reflected light of the light emitted from the illuminator from the mark, and captures the mark. A moving means for moving the lighting device so that an angle between the substrate surface at the position where the mark is provided and the lighting device changes, and an image signal captured by the imaging camera. A threshold value setting circuit for setting a level of a preset ratio as a reference threshold value with respect to the peak value of the reference value; a reference threshold value preset by the threshold value setting circuit; and an image signal of a mark separately imaged by the imaging camera. A threshold is calculated for the peak value based on the preset ratio, and the moving unit is controlled such that a difference between the calculated threshold and the reference threshold is minimized. A board mark recognition mechanism, comprising: a control circuit.