JP2020091203A - Projection device and three-dimensional measuring device - Google Patents

Abstract

To provide a projection device and a three-dimensional measuring device which can improve the accuracy of measurement when performing three-dimensional measurement that utilizes a pattern projection method.SOLUTION: A circuit board inspection device includes a projection device for projecting a stripe pattern W to a printed circuit board 1. The projection device comprises: a grid plate 20 for converting light entering from a prescribed light source into the stripe pattern W; an entering side lens 25 and an emitting side lens 26 constituting a both-side telecentric optical system for forming the image of the stripe pattern W on the printed circuit board 1; and a pattern cycle change mechanism 22 capable of changing the cycle of the projected stripe pattern W. The pattern cycle change mechanism 22 is constituted to be able to change a distance Ls between the entering side lens 25 and the emitting side lens 26 while maintaining a distance Lf1 between the grid plate 20 and the entering side lens 25 and a distance Lf2 between the emitting side lens 26 and the printed circuit board 1.SELECTED DRAWING: Figure 6

Description

The present invention relates to a projection device that projects a predetermined pattern of light when performing three-dimensional measurement using a pattern projection method such as a phase shift method, and a three-dimensional measurement device including the projection device.

Generally, when an electronic component is mounted on a printed circuit board, cream solder is first printed on a predetermined electrode pattern arranged on the printed circuit board. Next, the electronic component is temporarily fixed on the printed board based on the viscosity of the cream solder. After that, the printed circuit board is introduced into a reflow furnace and soldered by performing a predetermined reflow process. Nowadays, it is necessary to inspect the printed state of the cream solder before it is introduced into the reflow furnace, and a three-dimensional measuring device may be used for such inspection.

Conventionally, various three-dimensional measuring devices have been proposed that project a predetermined pattern of light to perform three-dimensional measurement. Among them, a three-dimensional measuring device using the phase shift method is well known.

A three-dimensional measurement device using the phase shift method is a projection device that projects pattern light having a striped light intensity distribution (hereinafter, referred to as “striped pattern”) onto an object to be measured such as a printed circuit board from diagonally above. , And an image pickup device for picking up an image of the measured object on which the stripe pattern is projected.

The projection device includes a light source that emits a predetermined light and a pattern generation unit that converts the light from the light source into a striped pattern, and the striped pattern generated here is projected through a projection optical system including a projection lens or the like. It is projected on the measured object.

Under such a configuration, the phase of the stripe pattern projected on the object to be measured is shifted in a plurality of ways (for example, four ways), and imaging is performed under each of the stripe patterns having different phases, so that a plurality of patterns related to the object to be measured are obtained. Get image data. Then, three-dimensional measurement of the object to be measured is performed based on these image data.

However, some of the measurement targets whose heights are actually measured are high in height and low in height. For example, regarding cream solder, the height of the cream solder printed on a conventional general printed circuit board is usually about 100 μm. Since the power circuit and the like are mounted, the height of the cream solder may be about 300 to 400 μm.

Here, for example, if a three-dimensional measuring device in which the period of the projected stripe pattern is made longer than in the past according to the vehicle printed circuit board is used, the height dynamic range is increased and the vehicle printed circuit board can be measured. However, when this is used for the measurement of the conventional general printed circuit board, the height resolution becomes rough and the measurement accuracy may be deteriorated.

Therefore, in order to make the three-dimensional measuring device versatile, a striped pattern having a long cycle is projected when the degree of unevenness of an object to be measured such as a printed circuit board is large, and a short cycle when the degree of unevenness is small. It is necessary to project a striped pattern according to the degree of unevenness of the measured object, such as projecting a striped pattern.

However, when a conventional grid plate in which a grid is printed on a film or a glass plate is used as the pattern generation unit, the width and pitch of the printed grid cannot be changed, so the stripe pattern projected on the measured object. Is constant.

Therefore, if an attempt is made to project different stripe patterns depending on the degree of unevenness of the object to be measured by a three-dimensional measuring device using a grid plate, a plurality of grid plates with different printed grid widths or pitches are prepared in advance. However, it is necessary to use these lattice plates properly according to the degree of unevenness of the measured object. As described above, the three-dimensional measuring device in which the grid plate has to be replaced each time is inconvenient and may cause a decrease in productivity.

On the other hand, as a pattern generation unit, a three-dimensional measurement device using a liquid crystal element in which a plurality of pixels are two-dimensionally arranged in a matrix is also found.

However, since the conventional liquid crystal element has a dark portion between pixels, the generated stripe pattern is microscopically discontinuous, so that the stripe pattern projected on the measured object is assumed. The striped pattern is not formed, and the measurement accuracy of the three-dimensional measurement may be reduced.

On the other hand, in recent years, in order to solve the above problems, a special liquid crystal element is used to change the width and pitch of the lattice according to the degree of unevenness of the object to be measured, which makes it possible to project a stripe pattern with different periods An original measuring device can also be seen (for example, refer to Patent Document 1).

Specifically, the three-dimensional measuring apparatus described in Patent Document 1 forms N stripe-shaped electrodes having a constant pitch and width on a liquid crystal element, and the stripes are formed at a number n of electrodes that is a multiple of 3 or 4. The live electrode is divided into N/n groups, one grating having a sinusoidal intensity distribution is created for each group, and one cycle of the sinusoidal wave is n or the like according to the number of electrodes n. And a liquid crystal drive signal corresponding to the sum of the amplitude of the sine wave of each divided region and the bias strength of the sine wave is applied to each of the stripe electrodes to obtain the sine wave strength. N/n grid patterns having a distribution are generated, and a voltage of the liquid crystal drive signal to be applied to the stripe electrodes is applied in units of a cycle obtained by dividing one cycle of the grid pattern into three or four. Is sequentially changed, the phase of the lattice pattern is shifted by 2π/3 or π/2 pitch, and the number n of electrodes is changed to form a lattice pattern suitable for the surface shape of the object to be measured. Is configured.

JP, 11-83454, A

However, the configuration according to Patent Document 1 requires the special liquid crystal element described above, which may increase the manufacturing cost of the projection apparatus.

Further, since the liquid crystal element passes through the polarization filter, the stripe pattern projected on the measured object may be dark. As a result, accurate luminance image data cannot be acquired, and the measurement accuracy of the three-dimensional measurement may decrease.

The above problem is not limited to three-dimensional measurement of cream solder or the like printed on a printed circuit board, but is inherent in other three-dimensional measurement fields. Of course, the problem is not limited to the phase shift method.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a projection apparatus and a three-dimensional measurement apparatus capable of improving the measurement accuracy when performing three-dimensional measurement using the pattern projection method. To do.

Hereinafter, each means suitable for solving the above-mentioned problems will be described by itemizing. In addition, the action and effect peculiar to the corresponding means will be additionally described as needed.

Means 1. A projection device for projecting a predetermined pattern light onto the object to be measured when performing three-dimensional measurement of the object to be measured (for example, a printed circuit board),
A light source that emits predetermined light,
A grating member for converting the light incident from the light source into the pattern light;
A projection optical system for forming an image of the pattern light emitted from the grating member on the object to be measured,
The projection optical system is
A grating side lens positioned on the grating member side with respect to the optical axis direction, and a both-side telecentric optical system including a measured object side lens positioned on the measured object side,
While maintaining the optical path length (optical distance) between the grating member and the lens on the grating side, and the optical path length between the lens on the object to be measured and the object to be measured, the lens on the grating side and the object to be measured side A projection apparatus comprising an optical path length changing means capable of changing an optical path length between lenses.

The "lattice member" is, for example, one in which a lattice is printed (deposited) on a flat or film-shaped substrate made of a translucent material such as glass or acrylic resin, or an opaque resin or metal. And a lattice is formed by forming slits and the like to form openings, and the like.

According to the above means 1, by using the lattice member as the pattern generation unit that converts the light from the light source into the pattern light, it is possible to project the pattern light that is brighter than that when the liquid crystal lattice or the like is used, and the optical path described above is used. By providing the length changing means, it is possible to change the period (pitch) of the pattern light projected on the object to be measured without exchanging the grating.

In addition, since an inexpensive lattice member such as an existing lattice plate in which a lattice is printed on a substrate such as a glass plate can be used, when an expensive optical control element such as a liquid crystal element is used as the pattern generation unit. In comparison, the manufacturing cost of the pattern generation unit can be suppressed.

Further, unlike the case of using an existing liquid crystal element or the like, it is not necessary to control the pixel, the control can be simplified, and the generated pattern light is microscopically discontinuous. Therefore, it becomes possible to project a more ideal pattern light onto the object to be measured.

In addition, the optical path length changing means uses the both-side telecentric optical system, and while maintaining the optical path length between the grating member and the grating side lens, and the optical path length between the measured object side lens and the measured object, Since the optical path length between the lens on the grating side and the lens on the measured object side is changed, it is not necessary to adjust the focus each time the cycle of the pattern light is changed.

If the projection optical system is not composed of a telecentric optical system on both sides, the focus position also changes when changing the optical path length between the lens on the grating side and the lens on the measured object side, so focus adjustment is performed. Therefore, some kind of correction mechanism is required.

In other words, this means does not need to have such a correction mechanism, and the configuration and control of the device can be further simplified.

Means 2. The optical path length changing means,
Maintaining the relative positional relationship (physical distance) between the grating member and the grating side lens in the optical axis direction, and the relative positional relationship between the measured object side lens and the measured object in the optical axis direction. At the same time, the projection apparatus according to means 1 has a configuration capable of changing a relative positional relationship between the grating side lens and the measured object side lens in the optical axis direction.

According to the above means 2, the configuration according to the above means 1 can be realized by using the existing optical zoom mechanism, so that the structure and control can be simplified and the manufacturing cost can be suppressed.

Means 3. The optical path length changing means,
The relative position between the grating side lens and the DUT side lens is provided by providing a moving means for moving the grating member and the grating side lens while maintaining the relative positional relationship between the grating member and the grating side lens. 3. The projection apparatus according to means 2, which has a configuration capable of changing the relationship.

The grating member and the lens on the grating side can be moved together by a single moving means. On the other hand, regarding the object-to-be-measured lens and the object to be measured, when it is attempted to move them while maintaining the relative positional relationship between them, it is necessary to provide separate moving means for each and to control them synchronously. Control can be extremely complicated. Further, a larger-scale mechanism is required, which may increase the size of the apparatus, and it is difficult to perform a quick movement, and there is a concern that the cycle changing speed is lowered and the measurement speed is lowered.

In this respect, according to the means 3 described above, the function and effect of the means 1 described above can be obtained without causing such a problem.

Means 4. 2. The projection apparatus according to means 1, wherein the optical path length changing means is composed of a variable lens (for example, a liquid lens) capable of changing the optical path length from the entrance surface to the exit surface.

According to the above means 4, the relative positional relationship between the grating member and the grating side lens, the relative positional relationship between the grating side lens and the measured object side lens, and the relative positional relationship between the measured object side lens and the measured object are changed. Without changing the optical path length between the grating side lens and the measured object side lens.

By using the variable lens described above, the configuration relating to the optical path length changing unit can be made compact. In addition, quick movement is possible, and the cycle changing speed can be improved, which in turn can improve the measurement speed.

Further, it is possible to suppress vibrations or the like that may occur when the grating side lens or the like is physically moved. As a result, more accurate pattern light can be projected, and the measurement accuracy can be improved.

Means 5. 5. The projection device according to any one of means 1 to 4, wherein the grating member and the main surface of the projection optical system are arranged so as to satisfy the Scheimpflug condition with respect to the object to be measured.

According to the above means 5, the plane including the lattice plate (lattice printing surface), the plane including the main surface of the projection optical system, and the plane including the DUT (pattern projection surface) satisfy the Scheimpflug condition. In addition, the pattern light can be projected in the focused state over the entire projection range on the object to be measured by setting the lines so as to intersect with each other on the same straight line.

As a result, when performing three-dimensional measurement using the pattern projection method, it is possible to project pattern light with high measurement accuracy.

Even when the optical path length (relative positional relationship) between the lens on the grating side and the lens on the object to be measured changes, the Scheimpflug condition is satisfied, so even when the cycle of the projected pattern light is changed, Therefore, it is not necessary to adjust the inclination of the lattice member or the like.

Means 6. 6. The projection apparatus according to any one of means 1 to 5, characterized in that pattern light having a stripe-shaped (for example, sinusoidal) light intensity distribution can be projected as the pattern light.

According to the above means 6, by projecting the pattern light having the striped light intensity distribution, it is possible to perform the three-dimensional measurement by the phase shift method. As a result, it is possible to improve the measurement accuracy of the three-dimensional measurement.

In the configuration such as the phase shift method in which the three-dimensional measurement is performed based on the difference in the brightness value of the plurality of image data acquired by capturing under the pattern light having different phases, even if the error in the brightness value is small, , The measurement accuracy may be greatly affected. Therefore, under the configuration according to the present means, the action and effect of each of the above means will be more successful. In particular, pattern light having a sinusoidal light intensity distribution is likely to collapse the light intensity distribution (waveform), and thus high projection accuracy is required.

Means 7. A projection device according to any one of means 1 to 6;
An image capturing unit capable of capturing an image of a predetermined range of the measured object onto which the pattern light is projected;
A three-dimensional measuring device comprising: an image processing unit capable of performing three-dimensional measurement of the object to be measured based on the image data captured and acquired by the image capturing unit.

According to the above means 7, three-dimensional measurement can be performed by using the pattern light projected from the projection device according to any one of the means 1 to 6. Usually, when performing three-dimensional measurement using the pattern projection method, the light emitted from a predetermined light source is converted into a predetermined pattern light in a pattern generation unit (lattice member), and measurement is performed via a projection optical system. Project on an object. Then, the object to be measured onto which the pattern light is projected is imaged by the image pickup means, and the three-dimensional measurement of the object to be measured is performed based on the acquired image data.

More specifically, as a three-dimensional measurement device that performs three-dimensional measurement by the phase shift method using the pattern light projected from the projection device according to the above means 6,
“A projection device according to means 6,
An image capturing unit capable of capturing an image of a predetermined range of the measured object onto which the pattern light is projected;
Displacement means for displacing the relative positional relationship (phase) between the pattern light projected by the projection device and the object to be measured,
In a state where the relative positional relationship between the pattern light and the measured object is different, the measured object is related to the measured object by a phase shift method based on a plurality of image data of the measured object captured and captured by the imaging unit. A three-dimensional measuring apparatus, comprising: an image processing unit capable of performing three-dimensional measurement. Is given as an example.

Examples of the "measurement object" include a printed circuit board on which cream solder is printed. That is, by using the projection device described in each of the above means, it is possible to perform three-dimensional measurement of the cream solder printed on the printed circuit board. As a result, in the inspection of the cream solder, the quality of the cream solder can be judged based on the measured value. Therefore, in such an inspection, the effects of each of the above-described means are exhibited, and it is possible to accurately determine the quality. As a result, it is possible to improve the inspection accuracy in the solder printing inspection device.

It is a schematic diagram which shows schematic structure of a board|substrate inspection apparatus. It is a plane schematic diagram which shows schematic structure of a printed circuit board. It is a cross-sectional schematic diagram of a printed circuit board. It is a schematic diagram which shows the aspect of the striped pattern projected on the printed circuit board. It is a schematic diagram which shows schematic structure of a projection apparatus. (A), (b) is a schematic diagram for demonstrating the pattern period change mechanism of a projection apparatus. It is a block diagram which shows the electric constitution of a board|substrate inspection apparatus. (A), (b) is a schematic diagram for demonstrating the pattern period change mechanism of the projection apparatus which concerns on another embodiment.

[First Embodiment]
Hereinafter, an embodiment will be described with reference to the drawings. First, the configuration of the printed circuit board 1 which is the object to be measured in this embodiment will be described in detail (see FIGS. 2 and 3). FIG. 2 is a schematic plan view showing a schematic configuration of the printed board 1. FIG. 3 is a schematic sectional view of the printed circuit board 1.

As shown in FIGS. 2 and 3, the printed circuit board 1 is formed by forming an electrode pattern 3A made of copper foil and a land 3B on the surface of a flat base substrate 2 made of glass epoxy resin or the like. A resist film 4 is coated on the surface of the base substrate 2 except the land 3B and the vicinity thereof. Then, the solder paste 5 is printed on the land 3B.

The printed circuit board 1 according to the present embodiment is a vehicle-mounted printed circuit board mounted on, for example, an electric vehicle, and includes a power circuit unit PA on which electronic components such as an inverter circuit through which a relatively large load current flows are mounted. The control circuit section PB, on which electronic components such as a control circuit for controlling this, through which a relatively small signal current flows, is mounted is mixed.

Next, the board inspection apparatus 10 that constitutes the three-dimensional measurement apparatus according to this embodiment will be described in detail (see FIG. 1 ). FIG. 1 is a schematic diagram showing a schematic configuration of the board inspection apparatus 10. In the following description, the horizontal direction of the paper surface of FIG. 1 will be referred to as the “X-axis direction”, the front-back direction of the paper surface will be referred to as the “Y-axis direction”, and the vertical direction of the paper surface (vertical direction) will be referred to as the “Z-axis direction”.

The board inspection device 10 is a solder printing inspection device that inspects the printing state of the cream solder 5 printed on the printed board 1. The board inspection device 10 includes a transfer mechanism 11 that transfers and positions the printed board 1, an inspection unit 12 that inspects the printed board 1, and a drive control of the transfer mechanism 11 and the inspection unit 12. The control device 13 (see FIG. 7) for performing various controls, image processing, and arithmetic processing in the inside.

The transport mechanism 11 includes a pair of transport rails 11a arranged along the transport direction of the printed circuit board 1 (Y-axis direction), an endless conveyor belt 11b rotatably disposed with respect to each transport rail 11a, The controller 13 includes drive means (not shown) such as a motor for driving the conveyor belt 11b, and a chuck mechanism (not shown) for positioning the printed circuit board 1 at a predetermined position.

Under the above configuration, the printed circuit board 1 carried into the board inspection apparatus 10 has both side edges in the width direction (X-axis direction) orthogonal to the carrying direction inserted into the carrying rails 11a and on the conveyor belt 11b. Placed. Then, the conveyor belt 11b starts operating, and the printed circuit board 1 is conveyed to a predetermined inspection position. When the printed circuit board 1 reaches the inspection position, the conveyor belt 11b stops and the chuck mechanism operates. By the operation of the chuck mechanism, the conveyor belt 11b is pushed up, and both side edges of the printed circuit board 1 are clamped by the conveyor belt 11b and the upper side of the transport rail 11a. As a result, the printed circuit board 1 is positioned and fixed at the inspection position. When the inspection is completed, the fixing by the chuck mechanism is released, and the conveyor belt 11b starts operating. As a result, the printed board 1 is unloaded from the board inspection apparatus 10. Of course, the configuration of the transport mechanism 11 is not limited to the above-mentioned form, and other configurations may be adopted.

The inspection unit 12 is arranged above the transport path of the printed circuit board 1 (a pair of transport rails 11a). The inspection unit 12 projects a stripe pattern W (see FIG. 4) obliquely from above onto a predetermined inspection range on the printed board 1, and a predetermined area on the printed board 1 onto which the stripe pattern W is projected. A camera 15 as an image pickup unit that images the inspection range from directly above, an X-axis moving mechanism 16 (see FIG. 7) that enables movement in the X-axis direction, and a Y-axis that enables movement in the Y-axis direction. It is provided with a moving mechanism 17 (see FIG. 7) and is drive-controlled by the controller 13.

As shown in FIG. 2, the predetermined inspection range on the printed circuit board 1 includes a plurality of areas (previously set on the printed circuit board 1 with the size of the imaging field of view (imaging range) K of the camera 15 as one unit. It is one of the inspection ranges “1” to “15”).

The control device 13 drives and controls the X-axis moving mechanism 16 and the Y-axis moving mechanism 17 so that the inspection unit 12 (imaging field of view K) is positioned and fixed at the inspection position in an arbitrary inspection range on the printed circuit board 1. Can be moved to the upper position. Then, while sequentially moving the inspection unit 12 to a plurality of inspection ranges set on the printed circuit board 1, the inspection processing for each inspection range is executed, thereby performing the solder print inspection for the entire printed circuit board 1. It is configured to do.

As shown in FIG. 5, the projection device 14 moves a light source 19 that emits a predetermined light, a grid plate 20 as a grid member that converts the light from the light source 19 into a stripe pattern W, and the grid plate 20. A grid moving mechanism (not shown), a projection lens group 21 as a projection optical system for forming an image of the striped pattern W generated by the grid plate 20 on the printed circuit board 1, and a striped pattern W projected on the printed circuit board 1. A pattern cycle changing mechanism 22 (see FIG. 6) capable of changing the cycle is provided, and the drive is controlled by the controller 13. The "pattern cycle changing mechanism 22" constitutes "optical path length changing means" in the present embodiment.

The projection device 14 is arranged such that its optical axis J1 is parallel to the X-Z plane and is inclined by a predetermined angle α (for example, 30°) with respect to the Z-axis direction.

The light source 19 is composed of a halogen lamp that emits white light. The light emitted from the light source 19 is incident on the grating plate 20 along the optical axis J1 in the state of being collimated through a pretreatment lens group or the like (not shown).

The lattice plate 20 is formed by printing (evaporating) a lattice 23 on a base material formed in a flat plate shape or a film shape with a predetermined light-transmitting material (for example, glass or acrylic resin). In the present embodiment, the grid plate 20 is arranged so that the printing surface (grid surface) of the grid 23 faces the projection lens group 21 side, that is, the light emission side.

The grating 23 is configured such that the light-transmitting portions 23a and the light-shielding portions 23b, which are linearly formed along the Y-axis direction, are alternately arranged in the XZ plane.

The projection lens group 21 has an entrance side lens 25 and an exit side lens 26, and these two lenses 25, 26 constitute a both-side telecentric optical system (both-side telecentric lens).

Here, the incident side lens 25 collects the light (stripe pattern W) emitted from the grating plate 20, and has a telecentric structure in which the optical axis J1 and the principal ray are parallel on the incident side. The incident side lens 25 corresponds to the grating side lens in the present embodiment.

The exit side lens 26 is for forming an image of the light (stripe pattern W) transmitted through the entrance side lens 25 on the printed circuit board 1, and the optical axis J1 and the principal ray are parallel to each other on the exit side. It has a telecentric structure. The exit side lens 26 corresponds to the measured object side lens in the present embodiment.

Next, the pattern cycle changing mechanism 22 will be described in detail with reference to FIG. As shown in FIG. 6, the pattern cycle changing mechanism 22 is provided along the optical axis J1 direction (left and right direction in FIG. 6) and has a fixed cylindrical portion 22A to which the emission side lens 26 is attached, and the fixed cylindrical portion 22A. A movable cylindrical portion 22B provided so as to be displaceable along the optical axis J1 direction and to which the grating plate 20 and the incident side lens 25 are attached, and a slide mechanism as a moving means for slidingly displacing the movable cylindrical portion 22B in the optical axis J1 direction. (Not shown), and the drive is controlled by the control device 13.

With this configuration, while maintaining the distance Lf1 between the grating plate 20 and the incident side lens 25 in the optical axis J1 direction and the distance Lf2 between the emission side lens 26 and the printed board 1 in the optical axis J1 direction, the optical axis J1 direction is maintained. It is possible to change the distance Ls between the incident side lens 25 and the exit side lens 26 in [see FIGS. 6(a) and 6(b)].

As a result, the projection device 14 can switch and project a plurality of types of stripe patterns W having different periods (stripe pitches). In the present embodiment, two types of stripe patterns W are projected by switching between a first stripe pattern W1 having a first cycle of 300 μm (height resolution 3 μm) and a second stripe pattern W2 having a second cycle of 1000 μm (height resolution 10 μm). It is configured to be possible. Here, the “first cycle 300 μm” corresponds to the “short cycle”, and the “second cycle 1000 μm” corresponds to the “long cycle”.

More specifically, the pattern period changing mechanism 22 is drive-controlled to set the distance Ls between the incident side lens 25 and the emitting side lens 26 to the first distance Ls1 [see FIG. 6(a)]. The striped pattern W projected on can be set to the short striped first striped pattern W1. By projecting the first stripe pattern W1, the cream solder 5 in the height range of 0 μm to 300 μm can be measured with an accuracy of “3 μm”.

On the other hand, by driving and controlling the pattern period changing mechanism 22 and setting the distance Ls between the incident side lens 25 and the emitting side lens 26 to the second distance Ls2 [see FIG. 6(b)], the image is projected onto the printed circuit board 1. The striped pattern W to be formed can be set as the second striped pattern W2 having a long period. By projecting the second stripe pattern W2, the cream solder 5 in the height range of 0 μm to 1000 μm can be measured with the accuracy of “10 μm”.

Further, in the projection device 14 according to the present embodiment, the optical axis J1 is set so that the stripe pattern W projected on the printed board 1 is focused in the entire projection range (the same range as the imaging visual field K in the present embodiment). On the other hand, the lattice plate 20 is set to be inclined (see FIG. 5). However, in FIGS. 6A and 6B, in order to simplify the configuration, the grating plate 20 is not tilted with respect to the optical axis J1 direction (left and right direction in FIG. 6), and its entrance surface 20a and exit surface ( It is illustrated in a state in which the lattice plane) 20b is arranged so as to be orthogonal to the optical axis J1.

Specifically, with respect to the printed circuit board 1, the emission surface 20b of the lattice plate 20 and the main surface of the projection lens group 21 are set so as to satisfy the Scheimpflug condition.

Here, the principle of Scheimpflug will be described with reference to FIG. The Scheimpflug principle is that a plane S1 including the exit surface 20b of the grating plate 20 and a plane S2 including the main surface of the projection lens group 21 are on the same straight line C (a straight line perpendicular to the plane of the paper at the point C in FIG. 5). In the case of intersecting with each other, the object plane S3 onto which the stripe pattern W is projected in focus also intersects on the same straight line C. Therefore, the condition based on such Scheimpflug principle is that the plane S1 including the emission surface 20b of the grating plate 20, the plane S2 including the main surface of the projection lens group 21, and the surface (projection surface) of the printed circuit board 1 are used. That is, the included planes S3 intersect with each other on the same straight line C.

With the above configuration, in the projection device 14, the light emitted from the light source 19 enters the entrance surface 20a of the grating plate 20. Then, it goes straight in the lattice plate 20 along the optical axis J1. The light transmitted through the lattice plate 20 is emitted as a striped pattern W from the emission surface (lattice surface) 20b of the lattice plate 20. Then, it is projected onto the printed circuit board 1 via the projection lens group 21.

As a result, in the present embodiment, as shown in FIG. 4, the stripe pattern W parallel to the transport direction (Y-axis direction) of the printed circuit board 1 is projected.

It should be noted that the light passing through the grating 23 is not a perfect parallel light in general, and the "bright part" and the "dark part" of the stripe pattern W are caused by the diffraction effect or the like at the boundary between the light transmitting part 23a and the light shielding part 23b. An intermediate gradation range is generated at the boundary of the. Therefore, the striped pattern W projected on the printed circuit board 1 becomes pattern light having a sinusoidal light intensity distribution along the direction (X axis direction) orthogonal to the transport direction (Y axis direction) of the printed circuit board 1. .. However, in FIG. 4, for simplification, the intermediate gradation region is omitted, and the stripe pattern W is illustrated as a bright and dark binary stripe pattern.

As shown in FIG. 1, the camera 15 includes an image pickup element 15a having a light receiving surface on which a plurality of light receiving elements are arranged two-dimensionally, and an image pickup field of the printed circuit board 1 on which the stripe pattern W is projected on the image pickup element 15a. It has an image pickup lens unit 15b as an image pickup optical system for forming an image of K, and its optical axis J2 is set along the vertical direction (Z axis direction) perpendicular to the upper surface of the printed board 1. In this embodiment, a CCD area sensor is used as the image sensor 15a.

The imaging lens unit 15b is composed of a both-side telecentric lens (both-side telecentric optical system) integrally including an object-side lens, an aperture stop, an image-side lens, and the like. However, in FIG. 1, the imaging lens unit 15b is illustrated as one lens for simplification.

Here, the object side lens collects the reflected light from the printed circuit board 1 and has a telecentric structure in which the optical axis J2 and the principal ray are parallel on the object side. The image-side lens is used to form an image of the light transmitted through the aperture stop from the object-side lens on the light-receiving surface of the image sensor 15a, and has a telecentric structure in which the optical axis J2 and the principal ray are parallel on the image side. Have.

The image data captured and acquired by the camera 15 is converted into a digital signal inside the camera 15 at any time, and then input to the control device 13 in the form of a digital signal and stored in an image data storage device 44 described later. It Then, the control device 13 executes image processing, arithmetic processing, and the like, which will be described later, based on the image data. The control device 13 constitutes the image processing means in this embodiment.

Next, the electrical configuration of the control device 13 will be described with reference to FIG. FIG. 7 is a block diagram showing the electrical configuration of the board inspection apparatus 10.

As shown in FIG. 7, the control device 13 includes a microcomputer 41 that controls the entire board inspection device 10, an input device 42 as an “input unit” including a keyboard, a mouse, a touch panel, a CRT, a liquid crystal, and the like. A display device 43 as a “display unit” having a display screen, an image data storage device 44 for storing image data captured by the camera 15 and the like, a three-dimensional measurement result obtained based on the image data, and the like. A calculation result storage device 45 for storing various calculation results, a setting data storage device 46 for storing various information such as Gerber data in advance, and the like.

The microcomputer 41 includes a CPU 41a as an arithmetic means, a ROM 41b for storing various programs, a RAM 41c for temporarily storing various data such as arithmetic data and input/output data, and the like electrically connected to the above-mentioned devices 42 to 46. It is connected to the. Further, it has a function of controlling input/output of various data and signals with the respective devices 42 to 46 and the like.

The setting data storage device 46 stores a plurality of inspection ranges set on the printed circuit board 1, information regarding the moving order of the imaging visual field K of the camera 15 with respect to the inspection ranges, and the like. Here, the “moving order of the imaging field of view K” defines in what order the imaging field of view K of the camera 15 is moved with respect to a plurality of inspection ranges set on the printed circuit board 1.

The plurality of inspection ranges on the printed circuit board 1 and the moving order of the imaging visual field K for these are set automatically in advance by a predetermined program based on Gerber data or the like or manually by an operator.

For example, in the example shown in FIG. 2, the movement order (inspection order) of the imaging visual field K is set with the inspection range in the upper right corner as a starting point. In FIG. 2, the area surrounded by the chain double-dashed line frame indicates the imaging visual field K (inspection range), and the circled numbers “1” to “15” in the frame indicate the inspection order. Further, in FIG. 2, the moving direction (moving path) of the imaging visual field K is indicated by a dotted arrow.

Next, the inspection routine of the printed board 1 performed by the board inspection device 10 will be described in detail. This inspection routine is executed by the control device 13 (microcomputer 41).

As described above, when the printed circuit board 1 carried into the board inspection device 10 is positioned and fixed at a predetermined inspection position, the control device 13 first executes the position detection process of the printed circuit board 1.

More specifically, the control device 13 detects a positioning mark (not shown) provided on the printed circuit board 1, detects the position information (coordinates) of the detected mark, and the position information of the mark stored in the Gerber data. Based on the (coordinates), position information (tilt, position shift, etc.) of the printed circuit board 1 is calculated. As a result, the position detection process of the printed circuit board 1 is completed. Then, based on the position information of the printed circuit board 1, a correction process for correcting the deviation of the relative positional relationship between the inspection unit 12 (camera 15) and the printed circuit board 1 is executed.

After that, according to the inspection order stored in the setting data storage device 46, a movement process for moving the inspection unit 12 to the position corresponding to the “1”th inspection range on the printed circuit board 1 is executed.

During this time, the control device 13 executes a process of adjusting the cycle of the stripe pattern W projected on the “1”-th inspection range to a cycle corresponding to the inspection range based on the Gerber data stored in the setting data storage device 46. To do.

As shown in FIG. 2, in the present embodiment, since the “1”-th inspection range is the control circuit unit PB, the first stripe pattern W1 having a short cycle is set here.

When the moving process of the inspection unit 12 is completed and the imaging visual field K of the camera 15 is adjusted to the “1”-th inspection range on the printed board 1, the projection device 14 projects the first stripe pattern W1 to print the printed board. The inspection process related to the “1”-th inspection range above 1 is executed. Details of the inspection process will be described later (the same applies to inspection processes related to other inspection ranges).

After that, when the inspection process related to the “1”-th inspection range on the printed circuit board 1 is completed, the inspection unit 12 is moved to the “2”-th inspection on the printed circuit board 1 in accordance with the inspection order stored in the setting data storage device 46. The movement process of moving to the position corresponding to the range is started.

During this time, the control device 13 executes the process of adjusting (changing) the cycle of the stripe pattern W projected on the “2”-th inspection range to the cycle corresponding to the inspection range, as described above.

As shown in FIG. 2, in the present embodiment, the "2"th inspection range is the power circuit unit PA, so here, the second stripe pattern W2 having a long cycle is set.

When the moving process of the inspection unit 12 is completed and the imaging visual field K of the camera 15 is adjusted to the “2”-th inspection range on the printed board 1, the projection device 14 projects the second stripe pattern W2 to print the printed board. The inspection process related to the “2”-th inspection range above 1 is executed.

After that, when the inspection process related to the "2"th inspection range on the printed circuit board 1 is completed, the inspection unit 12 is moved to the "3"th inspection range on the printed circuit board 1 in accordance with the inspection order stored in the setting data storage device 46. The movement process of moving to the position corresponding to the range is started.

Similarly, thereafter, the inspection processing is executed for the “3”th to “15th” inspection ranges on the printed circuit board 1 by the stripe pattern W (first stripe pattern W1 or second stripe pattern W2) corresponding to the inspection range. As a result, the solder printing inspection for the entire printed circuit board 1 is completed.

Next, the inspection process performed in each inspection range of the printed circuit board 1 will be described. The inspection process is executed by the control device 13 (microcomputer 41).

In the present embodiment, for each inspection range, while changing the phase of the stripe pattern W projected from the projection device 14, the imaging processing is performed four times under the stripe pattern W having different phases, so that the light intensity distribution Acquire four different types of image data. The details will be described below.

As described above, the control device 13 first drives and controls the X-axis moving mechanism 16 and the Y-axis moving mechanism 17 to move the inspection unit 12, so that the imaging visual field K of the camera 15 falls within a predetermined inspection range of the printed circuit board 1. Align. At the same time, the lattice plate 20 of the projection device 14 is moved and controlled, and the position of the lattice 23 formed on the lattice plate 20 is set to a predetermined reference position (for example, the position of the phase “0°”).

When the positioning of the lattice plate 20 is completed, the control device 13 causes the light source 19 of the projection device 14 to emit light, projects a predetermined stripe pattern W (first stripe pattern W1 or second stripe pattern W2), and causes the camera 15 to operate. The drive is controlled to execute the first imaging process under the stripe pattern W.

After that, the control device 13 turns off the light source 19 and executes the moving process of the lattice plate 20 at the same time as the end of the first imaging process under the predetermined stripe pattern W. Specifically, the position of the grating 23 formed on the grating plate 20 is moved from the reference position to the second position where the phase of the stripe pattern W is shifted by a quarter pitch (90°).

When the moving process of the lattice plate 20 is completed, the control device 13 causes the light source 19 to emit light, projects a predetermined stripe pattern W, and drives and controls the camera 15 for the second time under the stripe pattern W. The imaging process is executed.

After that, by repeating the same process, four types of image data having different light intensity distributions are acquired under the stripe pattern W having different phases by 90° (each quarter pitch). This makes it possible to acquire four types of image data in which the phase of the fringe pattern W having a sinusoidal light intensity distribution is shifted by 90°.

Then, the control device 13 performs three-dimensional measurement of the cream solder 5 (height of each coordinate) by a known phase shift method based on the four types of image data (four luminance values of each coordinate) acquired as described above. (Measurement) is performed, and the measurement result is stored in the calculation result storage device 45.

Here, a known phase shift method will be described. Light intensities (luminances) I0, I1, I2, and I3 at predetermined coordinate positions on the printed circuit board 1 in the above four types of image data are expressed by the following equations (1), (2), (3), and (4), respectively. be able to.

I0=αsinθ+β (1)
I1=αsin(θ+90°)+β=αcos θ+β (2)
I2=αsin(θ+180°)+β=−αsinθ+β (3)
I3=αsin(θ+270°)+β=−αcos θ+β (4)
However, α: gain, β: offset, θ: phase of fringe pattern.

Then, by solving the above equations (1), (2), (3), and (4) for the phase θ, the following equation (5) can be derived.

θ=tan ⁻¹ {(I0-I2)/(I1-I3)} ··· (5)
By using the phase θ calculated in this way, the height (Z) at each coordinate (X, Y) on the printed circuit board 1 can be obtained based on the principle of triangulation.

Next, the control device 13 performs quality determination processing of the printing state of the cream solder 5 based on the three-dimensional measurement result (height data at each coordinate) obtained as described above. Specifically, the control device 13 determines a predetermined height from a height reference plane determined for each inspection range (power circuit unit PA, control circuit unit PB) based on the measurement result of the inspection range obtained as described above. The amount of the printed cream solder 5 is calculated by detecting the printing range of the cream solder 5 that has become longer than the length and integrating the height of each part within this range.

Subsequently, the control device 13 uses the data of the position, the area, the height, or the amount of the cream solder 5 thus obtained as the reference data (gerber data or the like) stored in the setting data storage device 46 in advance. A comparison judgment is made, and whether the print state of the cream solder 5 in the inspection range is good or bad is judged depending on whether or not the comparison result is within the allowable range.

After the acquisition of the four types of image data, the control device 13 moves the inspection unit 12 to the next inspection range while the quality determination processing is being performed. Thereafter, the series of processes described above is repeatedly performed in all the inspection ranges on the printed circuit board 1, and the solder print inspection for the entire printed circuit board 1 is completed.

As described above in detail, according to the present embodiment, the projection device 14 projects the stripe pattern W onto the printed circuit board 1 and acquires four types of image data in which the phases of the stripe pattern W are different, Three-dimensional measurement of the printed circuit board 1 by the phase shift method is performed based on these image data.

At this time, in this embodiment, the cycle (pitch) of the stripe pattern W projected from the projection device 14 is changed according to the degree of unevenness of the inspection range on the printed circuit board 1. Specifically, two types of stripe patterns W, that is, the first stripe pattern W1 having a short cycle and the second stripe pattern W2 having a long cycle are switched and projected.

Particularly, according to the projection device 14 according to the present embodiment, by using the lattice plate 20 as the pattern generation unit that converts the light from the light source 19 into the striped pattern W, the striped pattern W that is brighter than when a liquid crystal lattice or the like is used. And the pattern period changing mechanism 22 can change the period of the stripe pattern W projected on the printed circuit board 1 without replacing the lattice plate 20.

Further, in the present embodiment, since an inexpensive optical member such as the existing lattice plate 20 in which the lattice 23 is printed on the substrate such as a glass plate can be used as the pattern generation unit, it is possible to use an optical element such as an expensive liquid crystal element. The manufacturing cost of the pattern generation unit can be suppressed as compared with the case where the control element is used as the pattern generation unit.

Further, unlike the case where an existing liquid crystal element or the like is used, it is not necessary to control the pixel, the control can be simplified, and the generated stripe pattern W becomes microscopically discontinuous. Since this is not the case, a more ideal stripe pattern W can be projected onto the printed circuit board 1.

In addition, the projection lens group 21 is configured by a both-side telecentric optical system, and the pattern period changing mechanism 22 allows the distance Lf1 between the grating plate 20 and the incident side lens 25 in the optical axis J1 direction and the optical axis J1 direction. Since the distance Ls between the incident side lens 25 and the exit side lens 26 in the optical axis J1 direction is changed while maintaining the distance Lf2 between the exit side lens 26 and the printed circuit board 1, the period of the stripe pattern W is changed. It is not necessary to carry out focus adjustment or the like each time when the is changed.

If the projection lens group 21 is not composed of a double-sided telecentric optical system, the focus position also changes when the distance Ls between the incident side lens 25 and the emission side lens 26 changes, so focus adjustment is performed. Some kind of correction mechanism is required to do this.

In other words, according to the present embodiment, it is not necessary to provide such a correction mechanism, and the configuration and control of the device can be further simplified.

Further, the pattern cycle changing mechanism 22 according to the present embodiment is provided along the optical axis J1 direction, and the fixed cylindrical portion 22A to which the emitting side lens 26 is attached, and the fixed cylindrical portion 22A along the optical axis J1 direction. The movable-side cylindrical portion 22B, which is displaceably provided and to which the grating plate 20 and the incident-side lens 25 are attached, and the slide mechanism as a moving means for slidingly displacing the movable cylindrical portion 22B in the optical axis J1 direction. The distance Ls between the lens 25 and the exit side lens 26 is changed.

The grating plate 20 and the incident side lens 25 can be collectively moved by a single moving unit (sliding mechanism). On the other hand, when the output side lens 26 and the printed circuit board 1 are to be moved while maintaining the relative positional relationship between them, it is necessary to provide separate moving means for them and to control them synchronously. Can be very complex. Further, a larger-scale mechanism is required, which may increase the size of the apparatus, and it is difficult to perform a quick movement, and there is a concern that the cycle changing speed is lowered and the measurement speed is lowered.

In this respect, according to the present embodiment, it is possible to obtain the various operational effects described above without causing such a problem.

Further, in the projection device 14 according to the present embodiment, the emission surface 20b of the lattice plate 20 and the main surface of the projection lens group 21 are set so as to satisfy the Scheimpflug condition with respect to the printed circuit board 1.

That is, the plane S1 including the emission surface 20b of the lattice plate 20, the plane S2 including the main surface of the projection lens group 21, and the plane S3 including the surface (projection surface) of the printed circuit board 1 intersect each other on the same straight line C. Is set to.

As a result, the stripe pattern W can be projected in the focused state over the entire projection range on the printed circuit board 1. As a result, when performing three-dimensional measurement using the pattern projection method, it is possible to project pattern light with high measurement accuracy.

[Second Embodiment]
Next, the second embodiment will be described in detail with reference to FIG. In the present embodiment, in the projection device 14, the configuration relating to the pattern cycle changing mechanism (optical path length changing means) capable of changing the cycle of the striped pattern W is different from that of the first embodiment.

The pattern cycle changing mechanism 22 according to the first embodiment changes the physical distance Ls between the incident side lens 25 and the emitting side lens 26 by slidingly displacing the incident side lens 25 and the like along the optical axis J1 direction. However, in the present embodiment, the optical distance (optical path length) between the entrance-side lens 25 and the exit-side lens 26 remains constant while the physical distance Ls between the entrance-side lens 25 and the exit-side lens 26 remains constant. ) Is configured to change only. The details will be described below.

In addition, about the part which overlaps with the said 1st Embodiment, the detailed description is abbreviate|omitted using the same member name and the same code|symbol, and below, focusing on the part different from 1st Embodiment. I will explain.

As shown in FIGS. 8A and 8B, in the projection device 14 according to the present embodiment, the grating plate 20, the incident side lens 25, and the incident side lens 25 are provided with respect to the fixed cylindrical portion 100 provided along the optical axis J1 direction. The emission side lens 26 is attached and fixed.

Further, a variable lens 110, which constitutes a pattern period changing mechanism (optical path length changing means), is attached and fixed to the fixed barrel portion 100 between the incident side lens 25 and the emitting side lens 26.

The variable lens 110 according to the present embodiment includes a pair of transparent resin plates 111A and 111B provided in the optical axis J1 direction, and a liquid filled in a cavity formed between the pair of transparent resin plates 111A and 111B ( (For example, silicon oil) 112, and a liquid amount adjusting mechanism (not shown) capable of adjusting the volume of the liquid 112 in the cavity, by increasing or decreasing the volume of the liquid 112 in the cavity, The physical distance (thickness) from the transparent resin plate 111A on the incident surface side to the transparent resin plate 111B on the outgoing surface side can be changed.

Here, the liquid 112 filled in the variable lens 110 has a predetermined refractive index higher than that of air. Therefore, the optical path length of the light traveling in the variable lens 110 is optically longer than the optical path length of the light traveling in the air. Therefore, if the physical distance from the transparent resin plate 111A to the transparent resin plate 111B of the variable lens 110 increases, the optical distance from the incident side lens 25 to the emission side lens 26 also increases.

With this configuration, according to the present embodiment, the optical distance between the incident side lens 25 and the emitting side lens 26 is maintained while maintaining the physical distance Ls between the incident side lens 25 and the emitting side lens 26 in the optical axis J1 direction constant. Only the target distance (optical path length) can be changed [see FIGS. 8(a) and 8(b)].

For example, if the volume of the liquid 112 in the variable lens 110 is reduced and the thickness of the variable lens 110 is reduced [see FIG. 8(a)], the optical path length (optical distance) between the incident side lens 25 and the emission side lens 26 is reduced. The striped pattern W which becomes shorter and is projected on the printed circuit board 1 becomes the first striped pattern W1 having a short period.

On the other hand, if the volume of the liquid 112 in the variable lens 110 is increased and the thickness of the variable lens 110 is increased [see FIG. 8B], the optical path length (optical distance) between the incident side lens 25 and the emission side lens 26. Becomes longer, and the striped pattern W projected on the printed circuit board 1 becomes the second striped pattern W2 having a long period.

As described in detail above, according to this embodiment, the same operational effects as those of the above-described first embodiment are exhibited.

Particularly, in the present embodiment, the relative positional relationship between the grating plate 20 and the incident side lens 25, the relative positional relationship between the incident side lens 25 and the outgoing side lens 26, and the relative positional relationship between the outgoing side lens 26 and the printed circuit board 1 are changed. Without changing the optical path length between the incident side lens 25 and the output side lens 26.

By using the variable lens 110, the configuration relating to the optical path length changing unit can be made compact. In addition, quick movement is possible, and the cycle changing speed can be improved, which in turn can improve the measurement speed.

Further, it is possible to suppress vibrations and the like that may occur when the incident side lens 25 and the like are physically moved. As a result, more accurate pattern light can be projected, and the measurement accuracy can be improved.

It should be noted that the present invention is not limited to the contents described in the above embodiment, and may be implemented as follows, for example. Of course, other application examples and modification examples not illustrated below are naturally possible.

(A) In each of the above embodiments, the projection device and the three-dimensional measuring device according to the present invention are embodied in the board inspection device 10 that inspects the printing state of the cream solder 5 printed on the printed board 1. The invention is not limited to this, and may be embodied in an apparatus for inspecting another target such as an electronic component mounted on a printed circuit board. Needless to say, three-dimensional measurement may be performed by using an object different from the substrate as the object to be measured.

(B) In each of the above-described embodiments, the printed circuit board 1 in which the power circuit unit PA and the control circuit unit PB are mixed is used as the object to be measured, and the power circuit unit PA on the printed circuit board 1 has a second stripe with a long period. For example, the pattern W2 is projected to perform three-dimensional measurement, and the short-cycle first stripe pattern W1 is projected to the control circuit unit PB to perform three-dimensional measurement. The cycle of the stripe pattern W is switched according to the degree of unevenness.

Not limited to this, a printed circuit board having only the power circuit section PA is used as an object to be measured, and only the second striped pattern W2 having a long period is projected on the object to be three-dimensionally measured, and only the control circuit section PB is provided. The measured printed board is used as an object to be measured, and only the first striped pattern W1 having a short cycle is projected on the measured board to perform three-dimensional measurement. For example, the striped pattern W is manufactured according to the type of the printed board manufactured in the manufacturing line. The cycle may be switched.

Further, a plurality of short cycle first stripe patterns W1 and long cycle second stripe patterns W2 may be projected on the power circuit section PA in plural ways, and the two may be combined to perform three-dimensional measurement. Good. Thereby, although the measurement time is increased, the dynamic range can be expanded without lowering the height resolution.

(C) In each of the above-described embodiments, in performing three-dimensional measurement by the phase shift method, four types of image data in which the phase of the stripe pattern W differs by 90° are acquired. The phase shift amount is not limited to these. Other number of phase shifts and amount of phase shift that can be three-dimensionally measured by the phase shift method may be adopted. For example, three-dimensional measurement may be performed by acquiring three types of image data having different phases by 120° or 90°.

(D) In each of the above-described embodiments, the pattern light having the sinusoidal light intensity distribution is projected as the stripe pattern W when performing three-dimensional measurement by the phase shift method, but the present invention is not limited to this. As the stripe pattern W, for example, a pattern light having a non-sinusoidal light intensity distribution such as a rectangular wave shape or a triangular wave shape may be projected.

However, rather than projecting the pattern light having the non-sinusoidal light intensity distribution and performing the three-dimensional measurement, it is better to project the pattern light having the sinusoidal light intensity distribution and perform the three-dimensional measurement. Therefore, in order to improve the measurement accuracy, it is preferable that the pattern light having a sinusoidal light intensity distribution is projected to perform three-dimensional measurement.

(E) In each of the above-described embodiments, the stripe pattern W is projected on the printed circuit board 1 and the three-dimensional measurement is performed by the phase shift method. However, the present invention is not limited to this. For example, the spatial code method or the moire method is used. Alternatively, the configuration may be such that three-dimensional measurement is performed using another pattern projection method. However, when measuring a small measurement target such as the cream solder 5, it is more preferable to adopt a measurement method with high measurement accuracy such as a phase shift method.

(F) In each of the above-described embodiments, the inspection unit 12 (the projection device 14 and the camera 15) is sequentially moved with respect to a plurality of inspection ranges on the printed circuit board 1 fixed at predetermined positions, so that the entire area of the printed circuit board 1 is covered. It is configured to inspect. The configuration is not limited to this, and the inspection unit 12 may be fixed, and the printed circuit board 1 may be moved to inspect the entire area of the printed circuit board 1.

In each of the above-described embodiments, the projection device 14 is provided with the grid moving mechanism that moves the grid plate 20, so that the printed circuit board 1 fixed at a predetermined position without relatively moving the inspection unit 12 and the printed circuit board 1. The relative positional relationship between the stripe pattern W and the stripe pattern W projected thereon is moved (phase shifted). However, the structure (displacement means) for relatively moving the stripe pattern W and the printed circuit board 1 is the same as the above embodiment. It is not limited to the form.

For example, as described above, when the period of the projected stripe pattern W is not switched over the entire printed circuit board, the printed circuit board is continuously moved by a conveyor or the like, or the inspection unit 12 is continuously moved with respect to the fixed printed circuit board. As a result, the relative positional relationship between the printed board and the stripe pattern W projected on the printed board may be moved (phase shifted).

(G) In each of the above embodiments, the light source 19 is composed of a halogen lamp that emits white light. The configuration is not limited to this, and a configuration using another light source such as a white LED may be used.

(H) The configuration of the lattice plate is not limited to the above embodiments. For example, the grating plate 20 according to the above-described embodiment has a configuration in which the grating 23 is provided on the emitting surface 20b, but the configuration is not limited to this, and the grating 23 may be provided on the incident surface 20a, for example.

In each of the above-described embodiments, the lattice 23 is provided by printing (vapor deposition), but the configuration is not limited to this, and may be provided by another method such as laser processing.

The grating 23 according to each of the above-described embodiments has a binary configuration in which the light-transmitting portions 23a and the light-shielding portions 23b are alternately arranged, but the present invention is not limited to this, and for example, multi-values having different transmittances in three or more stages. It is also possible to adopt a configuration in which a typical lattice pattern is provided.

The lattice plate 20 according to each of the above-described embodiments is formed by printing (evaporating) the lattice 23 on a base material that is formed in a flat plate shape or a film shape with a predetermined light-transmitting material (for example, glass or acrylic resin). However, the present invention is not limited to this, and a grid plate or the like in which a grid is formed by processing an opaque resin, metal or the like and forming openings such as slits may be adopted.

(I) The configuration related to the projection optical system is not limited to the above embodiments. For example, in each of the above-described embodiments, the second stripe pattern W2 having a second cycle of 1000 μm is projected corresponding to the power circuit section PA on the printed circuit board 1, and the first cycle of 300 μm is projected corresponding to the control circuit section PB. The one-stripe pattern W1 is projected. The period and the number of stripe patterns W to be projected are not limited to these.

For example, three or more types of stripe patterns W having different cycles may be switched and projected according to the degree of unevenness of the inspection range on the printed circuit board 1.

(J) The configuration relating to the pattern period changing mechanism (optical path length changing unit) capable of changing the period of the striped pattern W is not limited to the above embodiments.

For example, the pattern period changing mechanism 22 according to the first embodiment described above is provided with a fixed cylindrical portion 22A provided along the optical axis J1 direction and to which the emitting side lens 26 is attached, and the fixed cylindrical portion 22A in the optical axis J1 direction. The movable cylinder portion 22B is provided so as to be displaceable along with the grating plate 20 and the incident side lens 25 attached thereto, and a slide mechanism as a moving means for slidingly displacing the movable cylinder portion 22B in the optical axis J1 direction. The distance Ls between the lens 25 and the exit side lens 26 is changed.

Not limited to this, the distance Ls between the incident side lens 25 and the emitting side lens 26 is changed by moving the emitting side lens 26 and the printed circuit board 1 with the grating plate 20 and the incident side lens 25 fixed. May be

However, in such a configuration, it is necessary to provide separate moving means for the emission side lens 26 and the printed circuit board 1, respectively, and the above-described various problems may occur. It is preferable to have such a configuration.

The configuration of the variable lens according to the second embodiment is not limited to the variable lens (liquid lens) 100. The physical distance Ls between the entrance-side lens 25 and the exit-side lens 26 remains constant, and only the optical distance (optical path length) between the entrance-side lens 25 and the exit-side lens 26 is changed. A lens (including a lens unit including a plurality of lenses) may be adopted.

(K) The image pickup means is not limited to the camera 15 of the above embodiment. For example, in the above embodiment, the CCD area sensor is adopted as the image pickup device 15a, but the present invention is not limited to this, and a CMOS area sensor or the like may be adopted.

Further, the imaging lens unit 15b is composed of a both-side telecentric lens (both-side telecentric optical system). Not limited to this, an object side telecentric lens (object side telecentric optical system) may be adopted as the imaging lens unit 15b. In addition, the configuration may not have a telecentric structure.

(L) In the projection device 14 according to each of the above-described embodiments, the emission surface 20b of the lattice plate 20 and the main surface of the projection lens group 21 are set so as to satisfy the Scheimpflug condition with respect to the printed circuit board 1.

Not limited to this, the Scheimpflug condition may not necessarily be set depending on the focused state of the stripe pattern W in the entire projection range.

DESCRIPTION OF SYMBOLS 1... Printed circuit board, 5... Cream solder, 10... Board inspection device, 12... Inspection unit, 13... Control device, 14... Projector, 15... Camera, 19... Light source, 20... Lattice board, 21... Projection lens group, 22... Pattern period changing mechanism, 23... Lattice, 23a... Light transmitting part, 23b... Light blocking part, 25... Incident side lens, 26... Emitting side lens, J1... Optical axis, PA... Power circuit part, PB... Control circuit part , W (W1, W2)... Stripe pattern.

Claims (7)

In performing three-dimensional measurement of a predetermined object to be measured, a projection device for projecting a predetermined pattern light onto the object to be measured,
A light source that emits predetermined light,
A grating member for converting the light incident from the light source into the pattern light;
A projection optical system for forming an image of the pattern light emitted from the grating member on the object to be measured,
The projection optical system is
A grating side lens positioned on the grating member side with respect to the optical axis direction, and a both-side telecentric optical system including a measured object side lens positioned on the measured object side,
An optical path length between the grating side lens and the measured object side lens while maintaining an optical path length between the grating member and the grating side lens and an optical path length between the measured object side lens and the measured object side lens A projection device comprising an optical path length changing means capable of changing the optical path length. The optical path length changing means,
While maintaining the relative positional relationship between the grating member and the grating side lens in the optical axis direction, and the relative positional relationship between the measured object side lens and the measured object in the optical axis direction, the optical axis The projection device according to claim 1, wherein the projection device has a configuration capable of changing a relative positional relationship between the grating side lens and the measured object side lens in a direction. The optical path length changing means,
The relative position between the grating side lens and the DUT side lens is provided by providing a moving means for moving the grating member and the grating side lens while maintaining the relative positional relationship between the grating member and the grating side lens. The projection device according to claim 2, wherein the projection device has a configuration capable of changing a relationship. The projection device according to claim 1, wherein the optical path length changing unit is configured by a variable lens capable of changing an optical path length from an incident surface to an emission surface. The projection device according to claim 1, wherein the grating member and the main surface of the projection optical system are arranged so as to satisfy the Scheimpflug condition with respect to the object to be measured. The projection device according to claim 1, wherein pattern light having a striped light intensity distribution can be projected as the pattern light. A projection device according to any one of claims 1 to 6,
An image capturing unit capable of capturing an image of a predetermined range of the measured object onto which the pattern light is projected;
A three-dimensional measuring device comprising: an image processing unit capable of performing three-dimensional measurement of the object to be measured based on the image data captured and acquired by the image capturing unit.

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