WO2019077797A1

WO2019077797A1 - Projection device and three-dimensional measurement device

Info

Publication number: WO2019077797A1
Application number: PCT/JP2018/022042
Authority: WO
Inventors: 二村　伊久雄; 大山　剛; 憲彦坂井田
Original assignee: Ckd株式会社
Priority date: 2017-10-17
Filing date: 2018-06-08
Publication date: 2019-04-25
Also published as: JP2019074426A

Abstract

Provided are a projection device and a three-dimensional measurement device that are able to achieve measurement accuracy improvement and the like when three-dimensional measurement using a pattern projection method is performed. In the present invention, a board inspection apparatus is provided with a projection device 14 that projects a stripe pattern onto a printed board, and a camera that captures an image of the printed board. The projection device 14 has a pattern generation unit 18 that converts light from a light source 17 to a stripe pattern, and a projection lens unit 19 that forms an image of the generated stripe pattern on the printed board. The pattern generation unit 18 comprises: a lattice plate 21 that converts incident light to a stripe pattern; an incident angle adjustment plate 22 that is disposed on the incident surface side of the lattice plate 21 such that an incident angle of the incident light is 0°; and a refraction angle adjustment plate 23 that is disposed on the emission surface side of the lattice plate 21 such that a refraction angle of emitted light is 0°, wherein these are composed of the same optical material having the same refractive index.

Description

Projection apparatus and three-dimensional measurement apparatus

The present invention relates to a projection apparatus for projecting a predetermined pattern light and a three-dimensional measurement apparatus equipped with the projection apparatus, when performing three-dimensional measurement using a pattern projection method such as a phase shift method.

Generally, when mounting an electronic component on a printed circuit board, cream solder is first printed on a predetermined electrode pattern disposed on the printed circuit board. Next, the electronic component is temporarily fixed on the printed circuit board based on the viscosity of the cream solder. Thereafter, the printed circuit board is introduced into a reflow furnace, and soldering is performed through a predetermined reflow process. Nowadays, it is necessary to inspect the printing condition of the cream solder before being introduced to the reflow furnace, and a three-dimensional measuring device may be used for such inspection.

Conventionally, various three-dimensional measurement devices have been proposed which perform three-dimensional measurement by projecting predetermined pattern light. Among them, a three-dimensional measurement apparatus using a phase shift method is well known.

A three-dimensional measurement apparatus using a phase shift method is a projection apparatus that projects pattern light having a stripe-like light intensity distribution (hereinafter, referred to as “stripe pattern”) obliquely upward onto an object to be measured such as a printed circuit board And an imaging device for imaging an object to be measured on which the fringe pattern is projected.

The projection apparatus includes a light source that emits predetermined light, and a pattern generation unit that converts light from the light source into a fringe pattern, and the fringe pattern generated here is a subject to be exposed via a projection optical system including a projection lens or the like. It is projected on the measurement object.

Under this configuration, the phase of the fringe pattern projected onto the object to be measured is shifted in a plurality of ways (for example, 4 ways), and imaging is performed under each fringe pattern different in phase, Acquire image data. Then, three-dimensional measurement of the object to be measured is performed based on these image data.

In recent years, a three-dimensional measurement apparatus has also been observed in which the pattern generation unit is disposed to be inclined with respect to the optical axis of the projection optical system according to the principle of shine proof, and a fringe pattern is focused over the entire projection range See, for example, Patent Documents 1 and 2).

Japanese Patent Publication No. 2003-527582 JP, 2014-106094, A

However, in the configuration in which the grating plate is used as the pattern generation unit as in Patent Document 1 and the grating plate is arranged to be inclined with respect to the optical axis of the projection optical system, as shown in FIG. The light Ka emitted from the light source obliquely enters the incident surface 100a of the grating plate 100 along the optical axis direction of the projection optical system. Under the present circumstances, unless it is the light of a single wavelength, the light Kb which injected will be disperse | distributed by the difference in the refractive index of a several wavelength component.

Furthermore, the light Kb transmitted through the inside of the lattice plate 100 is converted into a stripe pattern at the light emission surface (lattice surface) 100b, and is obliquely emitted from the light emission surface 100b. At this time, as in the case of incidence, the emitted light Kc is dispersed due to the difference in refractive index of a plurality of wavelength components.

As a result, the fringe pattern projected onto the object to be measured is blurred or the like, and the estimated fringe pattern may not be assumed, and the measurement accuracy of the three-dimensional measurement may be lowered.

On the other hand, in Patent Document 2, a pattern generation unit is an optical control element in which a plurality of pixels are two-dimensionally arranged in a matrix, such as a digital micro mirror device (DMD), a reflective liquid crystal panel, and a transmissive liquid crystal panel. The configuration used as is described.

However, since the optical control element such as the DMD has a dark portion between pixels, the stripe pattern generated is microscopically discontinuous. As a result, the fringe pattern projected onto the object to be measured does not become the assumed fringe pattern, and the measurement accuracy of the three-dimensional measurement may be reduced.

Further, the optical control element such as the DMD complicates the control of the projection apparatus and is expensive, which may increase the manufacturing cost of the projection apparatus.

The above problem is not necessarily limited to three-dimensional measurement of cream solder or the like printed on a printed circuit board, but is inherent in the field of other three-dimensional measurement. 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 measurement accuracy etc. when performing three-dimensional measurement using a pattern projection method. It is to do.

Hereinafter, each means suitable for solving the above-mentioned subject will be described by item. In addition, the operation and effect specific to the corresponding means will be added as needed.

Means 1. A projection apparatus for projecting a predetermined pattern of light onto an object to be measured when performing three-dimensional measurement on the object to be measured (for example, a printed circuit board),
A light source that emits a predetermined light;
A pattern generation unit that converts light incident from the light source into the pattern light and emits the light;
A projection optical system for forming an image of the pattern light emitted from the pattern generation unit on the object to be measured;
The pattern generation unit
A first light transmitting member (grating plate) made of an optical material (for example, glass or acrylic resin) having a predetermined refractive index and provided with a predetermined grating (grating plane) for converting incident light into the pattern light When,
It is made of a material having the same refractive index as the first light transmitting member, and is disposed on the light incident surface side of the first light transmitting member so that the incident angle of light incident on the pattern generating unit is 0 °. A second light transmitting member (incident angle adjusting plate),
It is made of a material having the same refractive index as the first light transmitting member, and is disposed on the light emitting surface side of the first light transmitting member so that the refraction angle of light emitted from the pattern generation unit is 0 °. Composed of a third light transmitting member (refractive angle adjusting plate),
1. A projector according to claim 1, wherein the grating of the first light transmitting member and the main surface of the projection optical system are arranged with respect to the object to be measured such that the conditions of the shine proof are satisfied.

According to the above-mentioned means 1, in performing three-dimensional measurement using a pattern projection method, it is possible to project pattern light with high measurement accuracy.

The projection apparatus according to this means is set such that the grating of the first light transmitting member and the main surface of the projection optical system satisfy the condition of the shine proof for the object to be measured. That is, on the same straight line, the plane including the grating of the first light transmitting member, the plane including the main surface of the projection optical system, and the plane including the object to be measured (pattern projection plane) satisfy the condition of shine proof. Are set to cross each other. Thus, the pattern light can be projected in focus on the entire projection range on the object to be measured. As a result, the measurement accuracy of three-dimensional measurement can be improved.

Furthermore, the pattern generation unit according to the present invention is configured such that the first light transmitting member provided with a predetermined grating for converting incident light into pattern light, and the first light transmitting member have an incident angle of 0.degree. (1) A second light transmitting member disposed on the light incident surface side of the light transmitting member, and a third light transmitting member disposed on the light exit surface side of the first light transmitting member so that the refraction angle of emitted light is 0 °. While being comprised by a light transmission member, each light transmission member is formed with the optical raw material (for example, glass, an acrylic resin, etc.) which has the same refractive index.

As a result, it is possible to suppress the dispersion and the like of the light transmitted through the pattern generation unit, and to suppress the blurring and the like of the projected pattern light. As a result, it is possible to improve the measurement accuracy of three-dimensional measurement using the pattern projection method.

In addition, according to the present means, it is possible to manufacture the pattern generation unit using an inexpensive light transmitting member such as, for example, an existing grid plate in which a grid is printed (deposited) on a glass plate. Therefore, the manufacturing cost of the projection apparatus can be suppressed as compared to the case where an expensive optical control element such as a DMD is used as the pattern generation unit.

Further, as in the case of using an optical control element such as DMD, there is no need to control the pixel, and the control can be simplified, and the pattern light generated becomes microscopically discontinuous. Because there is no problem, it becomes possible to project more ideal pattern light onto the object to be measured.

When an optical control element such as DMD is used as a pattern generation unit, a commercially available one is usually used. For this reason, the pattern light to be generated depends on the pixel pitch of the optical control element, the degree of freedom is reduced, and it may be difficult to project the pattern light suitable for the object to be measured. In this respect, according to the present means, it is possible to project pattern light more suitable for the object to be measured.

In addition, since the first light transmitting member (grid plate) is sandwiched between the second light transmitting member and the third light transmitting member, the deflection of the first light transmitting member is suppressed to improve the projection accuracy, and It can protect the face.

Means 2. The condition of the shine proof is that the difference in the optical path length from the grating of the first light transmitting member to the light emitting surface of the third light transmitting member in the traveling direction of light transmitted through the pattern generation unit is taken into consideration. The projection device according to the means 1 characterized by the above.

The optical path length from the grating of the first light transmitting member to the exit surface of the third light transmitting member in the traveling direction of light transmitted through the pattern generation unit is the grating of the first light transmitting member relative to the exit surface of the third light transmitting member It depends on which position on the grating in the tilt direction of the grating plane) the light passes through.

An optical material such as glass constituting each of the above-mentioned light transmitting members usually has a predetermined refractive index higher than the refractive index of air. Therefore, the optical path length of the light traveling in the light transmitting member is optically longer than the optical path length of the light traveling in the air. Therefore, when the physical length (optical path length) from the grating of the first light transmitting member to the light emitting surface of the third light transmitting member is different, the optical length from the grating of the first light transmitting member to the object to be measured is Different optical path lengths. In the case where the grating of the first light transmitting member and the main surface of the projection optical system are disposed so as to satisfy the condition of the shine proof without taking this into consideration, slight errors may occur.

On the other hand, according to the present means, the grid of the first light transmitting member and the main surface of the projection optical system are arranged so as to satisfy the condition of the shine proof in a state where such an error is corrected. The pattern light can be well focused.

Means 3. The projector according to the

means

1 or 2, characterized in that pattern light having a stripe-like (for example, sinusoidal wave) light intensity distribution can be generated as the pattern light.

According to the above-mentioned means 3, three-dimensional measurement by the phase shift method can be performed by projecting the pattern light having the stripe-like light intensity distribution. As a result, it is possible to improve the measurement accuracy of the three-dimensional measurement.

In a configuration that performs three-dimensional measurement based on differences in luminance values of a plurality of image data captured and acquired under pattern light with different phases, as in the phase shift method, even if the error in luminance values is slight There is a possibility that the measurement accuracy may be greatly affected. Therefore, under the configuration according to the present means, the action and effect of each means is more successful. In particular, pattern light having a sinusoidal light intensity distribution is likely to break the light intensity distribution (waveform), so high projection accuracy is required.

Means 4. The projection apparatus according to any one of the means 1 to 3;
An imaging unit capable of imaging a predetermined range of the object to be measured on which the pattern light is projected;
A three-dimensional measuring apparatus comprising: image processing means capable of executing three-dimensional measurement relating to the object based on image data captured and acquired by the imaging means.

According to the means 4, the three-dimensional measurement can be performed using the pattern light projected from the projection device according to any one of the means 1 to 3. In general, when performing three-dimensional measurement using a pattern projection method, light emitted from a predetermined light source is converted to predetermined pattern light in a pattern generation unit, and projected onto a measurement object via a projection optical system. Do. Then, the object to be measured on which the pattern light is projected is imaged by the imaging means, and three-dimensional measurement of the object to be measured is performed based on the acquired image data.

More specifically, as a three-dimensional measurement apparatus for performing three-dimensional measurement by a phase shift method using pattern light projected from the projection apparatus described in the above means 3,
“The projection device according to the means 3;
An imaging unit capable of imaging a predetermined range of the object to be measured on which the pattern light is projected;
Displacement means for displacing relative positional relation (phase) between the pattern light projected by the projection device and the object to be measured;
The object is measured by the phase shift method based on a plurality of image data of the object to be measured which is captured and acquired by the imaging unit in a state in which the relative positional relationship between the pattern light and the object to be measured is different. What is claimed is: 1. A three-dimensional measuring apparatus comprising: image processing means capable of performing three-dimensional measurement. "Is mentioned as an example.

In addition, as said "object to be measured", the printed circuit board in which cream solder was printed, the wafer board | substrate with which solder bump was formed, etc. are mentioned, for example. That is, three-dimensional measurement of cream solder printed on a printed circuit board and solder bumps formed on a wafer substrate can be performed by using the projection device described in each of the above-described means. As a result, in the inspection of the cream solder and the solder bumps, it is possible to determine the quality of the cream solder and the solder bumps based on the measured values. Therefore, in the inspection, the operation and effect of each of the above-described means are exhibited, and the quality determination can be performed with high accuracy. As a result, it is possible to improve the inspection accuracy in the solder printing inspection apparatus and the solder bump inspection apparatus.

It is a schematic diagram which shows schematic structure of a board | substrate test | inspection apparatus. It is a cross-sectional schematic diagram of a printed circuit board. It is a schematic diagram which shows schematic structure of a projection apparatus. It is a schematic diagram which shows schematic structure of a pattern production | generation part. It is a block diagram which shows the electric constitution of a board | substrate test | inspection apparatus. It is a schematic diagram which shows the aspect of the fringe pattern projected on the printed circuit board. It is a schematic diagram for demonstrating the relationship between the coordinate position on the printed circuit board which changes with progress of time, and the imaging range of a camera. It is a table | surface for demonstrating the relationship between the coordinate position on the printed circuit board which changes with progress of time, and the phase of a fringe pattern. It is the table | surface which showed typically the state which aligned the coordinate position of several image data. It is the table | surface which showed typically the state which arranged the data which concern on each coordinate position of a printed circuit board. It is a schematic diagram which shows schematic structure of the conventional lattice plate.

Hereinafter, an embodiment will be described with reference to the drawings. First, the configuration of the printed circuit board 1 to be an object to be measured in the present embodiment will be described in detail (see FIG. 2). FIG. 2 is a schematic cross-sectional view of the printed circuit board 1.

As shown in FIG. 2, the printed board 1 has a flat plate shape, and an electrode pattern 3 made of copper foil is provided on a base board 2 made of glass epoxy resin or the like. Furthermore, cream solder 4 is printed on a predetermined electrode pattern 3. The area where the cream solder 4 is printed is referred to as a "solder print area". Parts other than the solder print area are generically referred to as "background area". In this background area, an area where the electrode pattern 3 is exposed (symbol E1), an area where the base substrate 2 is exposed (symbol E2), and A region (symbol E3) coated with the resist film 5 and a region (symbol E4) coated with the resist film 5 on the electrode pattern 3 are included. The resist film 5 is coated on the surface of the printed circuit board 1 so that the cream solder 4 does not rest on other than the predetermined wiring portion.

Next, the substrate inspection apparatus 10 constituting the three-dimensional measurement apparatus in the present embodiment will be described in detail (see FIG. 1). FIG. 1 is a schematic view showing a schematic configuration of a substrate inspection apparatus 10. As shown in FIG. Hereinafter, the left and right direction in the drawing of FIG. 1 will be referred to as “X direction”, the front and back direction in the drawing will be referred to as “Y direction”, and the up and down direction (vertical direction) in the drawing will be described as “Z direction”.

The board inspection apparatus 10 is a solder printing inspection apparatus that inspects the printing state of the cream solder 4 printed on the printed board 1. The substrate inspection apparatus 10 includes a conveyor 13 as a conveying means (displacement means) for conveying the printed circuit board 1, a projection device 14 for projecting a stripe pattern from above obliquely onto the surface of the printed substrate 1, and projection of the stripe pattern. The camera 15 as an imaging unit for imaging the printed circuit board 1 from directly above, and various controls, image processing, and arithmetic processing in the substrate inspection apparatus 10 such as drive control of the conveyor 13, the projection device 14 and the camera 15. And a controller 16 (see FIG. 5).

The conveyor 13 is provided with driving means such as a motor (not shown), and the motor is driven and controlled by the control device 16 so that the printed circuit board 1 mounted on the upper surface (mounting surface) of the conveyor 13 is The sheet is continuously conveyed at a constant speed in a predetermined direction (right direction in FIG. 1). As a result, the imaging range (imaging area) W of the camera 15 moves relative to the printed circuit board 1 in the reverse direction (left direction in FIG. 1).

As shown in FIG. 3, the projection device 14 includes a light source 17 that emits predetermined light, a pattern generation unit 18 that converts light from the light source 17 into a stripe pattern, and a stripe pattern generated by the pattern generation unit 18. And a projection lens unit 19 as a projection optical system for forming an image on the printed circuit board 1.

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

The light source 17 is configured of a halogen lamp that emits white light. The light emitted from the light source 17 enters the pattern generation unit 18 along the optical axis J1 in a collimated state through a pretreatment lens group (not shown) and the like.

The pattern generation unit 18 is configured as one optical member in which three light transmitting members are bonded and integrated (see FIG. 4). FIG. 4 is a schematic view showing a schematic configuration of the pattern generation unit 18.

As shown in FIG. 4, the pattern generation unit 18 includes a grating plate 21 as a first light transmitting member that converts incident light into a stripe pattern and emits the stripe pattern, and a grating member 21 disposed on the incident side of the grating plate 21. 2 includes an incident angle adjusting plate 22 as a light transmitting member, and a refraction angle adjusting plate 23 as a third light transmitting member disposed on the exit side of the grating plate 21.

All of the grating plate 21, the incident angle adjusting plate 22 and the refraction angle adjusting plate 23 are formed of the same optical material (for example, glass, acrylic resin, etc.) having the same refractive index.

The lattice plate 21 is a flat light transmitting member having a rectangular cross section in the XZ plane and having four rectangular planes along the Y direction. The entrance surface 21a and the exit surface 21b are constituted by two rectangular planes parallel to each other, which are arranged to intersect the optical axis J1 among the four rectangular planes constituting the grating plate 21.

The grating plate 21 is arranged such that the perpendiculars of the incident surface 21a and the exit surface 21b are inclined at a predetermined angle β (for example, about 20 °) with respect to the optical axis J1.

A grating 25 is formed by printing (vapor deposition) on the exit surface 21 b of the grating plate 21. That is, the emitting surface 21 b of the grating plate 21 constitutes the grating surface in the present embodiment. The grating 25 is configured such that the light transmitting portions 25 a and the light shielding portions 25 b linearly formed along the Y direction are alternately arranged in the XZ plane.

The incident angle adjusting plate 22 is a light transmitting member having a triangular cross section in the XZ plane and having three rectangular planes along the Y direction. Of the three rectangular planes constituting the incident angle adjusting plate 22, the incident plane 22a and the exit plane 22b are constituted by two rectangular planes arranged to intersect the optical axis J1.

The incident surface 22a of the incident angle adjustment plate 22 is disposed to be orthogonal to the optical axis J1. On the other hand, the exit surface 22b is joined to the entrance surface 21a of the lattice plate 21 and is disposed so that the perpendicular thereof is inclined at the angle β with respect to the optical axis J1. That is, in the incident angle adjusting plate 22, the internal angle between the incident surface 22a and the outgoing surface 22b is the angle β.

Thereby, the incident angle of the light which injects into the pattern production | generation part 18 (incident surface 22a of the incident angle adjustment board 22) from the light source 17 will be 0 degree. On the other hand, the light emitted from the emission surface 22b of the incident angle adjustment plate 22 and incident on the incident surface 21a of the lattice plate 21 travels straight along the optical axis J1 without refraction of all wavelength components.

The refraction angle adjusting plate 23 is a light transmitting member having a triangular cross section in the XZ plane and having three rectangular planes along the Y direction. Of the three rectangular planes constituting the refraction angle adjusting plate 23, the entrance plane 23a and the exit plane 23b are constituted by two rectangular planes arranged to intersect the optical axis J1.

The entrance surface 23a of the refraction angle adjustment plate 23 is joined to the exit surface 21b of the grating plate 21 and is disposed so that the perpendicular thereof is inclined at the angle β with respect to the optical axis J1. On the other hand, the exit surface 23b is disposed to be orthogonal to the optical axis J1. That is, in the refraction angle adjustment plate 23, the internal angle between the incident surface 23a and the emission surface 23b is the angle β.

Thereby, the light (stripe pattern) emitted from the emission surface 21b of the grating plate 21 and incident on the incident surface 23a of the refraction angle adjustment plate 23 goes straight along the optical axis J1 without refraction of all wavelength components. It will be done. Further, the refraction angle of the light emitted to the outside from the pattern generation unit 18 (the emission surface 23 b of the refraction angle adjustment plate 23) is 0 °. Therefore, light emitted to the outside from the pattern generation unit 18 travels straight toward the projection lens unit 19 along the optical axis J1 without refraction of all wavelength components.

The projection lens unit 19 is configured by a both-side telecentric lens (both-side telecentric optical system) integrally including an incident side lens 31, an aperture stop 32, an exit side lens 33, and the like.

The incident side lens 31 condenses the light (stripe pattern) emitted from the pattern generation unit 18 (the emission surface 23b of the refraction angle adjustment plate 23), and the optical axis J1 and the chief ray are parallel on the incident side. Has a telecentric structure.

The exit side lens 33 is for forming an image of light (stripe pattern) transmitted from the entrance side lens 31 through the aperture stop 32 on the printed circuit board 1, and the light axis J1 and the chief ray are on the exit side. It has a telecentric structure that is parallel.

The aperture stop 32 is disposed at the position of the rear focal point of the incident side lens 31 and at the position of the front focal point of the output side lens 33.

Under this configuration, in the projection device 14, the pattern generation unit 18 and the projection are arranged such that the fringe pattern projected on the printed circuit board 1 is in focus over the entire projection range (the same range as the imaging range W in this embodiment). The tilt of the lens unit 19 is adjusted.

Specifically, with respect to the printed circuit board 1 on the conveyor 13, the exit surface (grid surface) 21b of the grid plate 21 and the main surface of the projection lens unit 19 are set to satisfy the condition of the shine proof.

Here, the principle of shine proof will be described with reference to FIG. The principle of shine proofing is that the plane S1 including the exit surface 21b of the lattice plate 21 and the plane S2 including the main surface of the projection lens unit 19 are the same straight line C (a straight line perpendicular to the paper at point C in FIG. 3) In the case of intersection at the top, the object surface S3 on which the fringe pattern is projected in the in-focus state also intersects on the same straight line C. Therefore, the conditions based on the principle of such a shine proof are the plane S1 including the exit surface 21b of the grating plate 21, the plane S2 including the main surface of the projection lens unit 19, and the surface (projection plane) of the printed board 1 The included planes S3 cross each other on the same straight line C.

Under the above configuration, the light emitted from the light source 17 is vertically incident on the pattern generation unit 18 (incident surface 22 a of the incident angle adjustment plate 22) at an incident angle of 0 °. Then, it travels straight in the incident angle adjustment plate 22 along the optical axis J1. The light transmitted through the inside of the incident angle adjustment plate 22 is emitted from the exit surface 22 b of the incident angle adjustment plate 22 and is obliquely incident on the incident surface 21 a of the grating plate 21 at the incident angle β. Then, it goes straight along the optical axis J1 in the lattice plate 21.

The light transmitted through the inside of the grating plate 21 is emitted as a stripe pattern from the exit surface (grating surface) 21 b of the grating plate 21 and obliquely enters the incident surface 23 a of the refraction angle adjusting plate 23 at the incident angle β. Then, it travels straight along the optical axis J1 in the refraction angle adjustment plate 23.

The light (stripe pattern) transmitted through the inside of the refraction angle adjustment plate 23 is vertically emitted from the emission surface 23 b of the refraction angle adjustment plate 23 at a refraction angle of 0 °. Then, it is projected onto the printed circuit board 1 through the projection lens unit 19.

Thus, in the present embodiment, as shown in FIG. 6, a stripe pattern parallel to the Y direction orthogonal to the transport direction (X direction) is projected onto the printed circuit board 1 to be transported.

In general, the light passing through the grating 25 is not a perfect parallel light, but the “light part” and “dark part” of the stripe pattern due to the diffraction action at the boundary between the light transmitting part 25 a and the light shielding part 25 b. An intermediate tone range will occur at the boundary. Therefore, the stripe pattern projected onto the printed circuit board 1 is pattern light having a light intensity distribution of a sine wave along the transport direction (X direction) of the printed circuit board 1. However, in FIG. 6, the middle gradation region is omitted for simplification, and the stripe pattern is illustrated by a stripe pattern of light and dark binary.

The camera 15 picks up an image of the image pickup area W of the printed circuit board 1 on which the stripe pattern is projected on the image pickup element 15a having a light receiving surface in which a plurality of light receiving elements are two-dimensionally arrayed. The imaging lens unit 15 b as an optical system is provided, and the optical axis J 2 thereof is set along the vertical direction (Z direction) perpendicular to the upper surface of the conveyor 13. In the present embodiment, a CCD area sensor is employed as the imaging element 15a.

The imaging lens unit 15b is configured by 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 a single lens for the sake of simplicity.

Here, the object side lens is for condensing the reflected light from the printed circuit board 1 and has a telecentric structure in which the optical axis J2 and the chief ray are parallel on the object side. The image side lens is for focusing the light transmitted through the aperture stop from the object side lens on the light receiving surface of the image pickup device 15a, and has a telecentric structure in which the optical axis J2 and the chief ray are parallel on the image side. Have.

The image data captured and acquired by the camera 15 is converted into a digital signal in the camera 15 and then input to the control device 16 in the form of a digital signal and stored in an image data storage device 44 described later. Then, based on the image data, the control device 16 performs image processing, arithmetic processing, and the like as described later. The control device 16 constitutes an image processing means in the present embodiment.

Next, the electrical configuration of the control device 16 will be described with reference to FIG. FIG. 5 is a block diagram showing the electrical configuration of the substrate inspection apparatus 10. As shown in FIG.

As shown in FIG. 5, the control device 16 includes a CPU and an input / output interface 41 that controls the entire substrate inspection apparatus 10, an input device 42 as an “input unit” configured of a keyboard, a mouse, a touch panel, etc. A display device 43 as "display means" having a display screen such as liquid crystal, an image data storage device 44 for storing image data etc. captured and acquired by the camera 15, three-dimensional obtained based on the image data An operation result storage device 45 for storing various operation results such as measurement results, and a setting data storage device 46 for previously storing various information such as design data are provided. The devices 42 to 46 are electrically connected to the CPU and the input / output interface 41.

Next, various processing such as three-dimensional measurement processing executed by the substrate inspection apparatus 10 will be described in detail.

The control device 16 drives and controls the conveyor 13 to continuously transport the printed circuit board 1 at a constant speed. Then, the control device 16 drives and controls the projection device 14 and the camera 15 based on a signal from an encoder (not shown) provided on the conveyor 13.

More specifically, every time the printed board 1 is transported by a predetermined amount Δx, that is, each time a predetermined time Δt elapses, the printed board 1 on which the stripe pattern is projected is imaged by the camera 15. Every time the predetermined time Δt elapses, the image data captured and acquired by the camera 15 is transferred to the control device 16 as needed, and stored in the image data storage device 44.

In the present embodiment, the predetermined amount Δx is set to a distance corresponding to a phase of 90 ° of the fringe pattern projected from the projection device 14. Further, the imaging range W of the camera 15 in the transport direction (X direction) of the printed circuit board 1 is set to a length corresponding to one cycle (phase 360 °) of the stripe pattern. Of course, the predetermined amount Δx and the imaging range W of the camera 15 are not limited to this, and may be longer or shorter.

Here, the relationship between the fringe pattern projected from the projection device 14 and the printed circuit board 1 imaged by the camera 15 will be described in detail by giving a specific example. FIG. 7 is a schematic view for explaining the relationship between the coordinate position on the printed circuit board 1 which moves relative to the passage of time and the imaging range W of the camera 15. As shown in FIG. FIG. 8 is a table for explaining the relationship between the coordinate position on the printed circuit board 1 which moves relative to the passage of time and the phase of the fringe pattern.

In the present embodiment, the entire range in the Y direction of the printed circuit board 1 is included in the imaging range W of the camera 15 with respect to the direction (Y direction) orthogonal to the transport direction (X direction) on the printed circuit board 1. Therefore, there is no difference in the phase of the fringe pattern at each coordinate position in the Y direction at the same coordinate position in the X direction. Further, since the positional relationship between the camera 15 and the projection device 14 is fixed, the phase of the fringe pattern projected from the projection device 14 is fixed with respect to each coordinate position on the light receiving surface of the imaging device 15a.

As shown in FIGS. 7 and 8, at a predetermined imaging timing t1, in the imaging range W of the camera 15, the range corresponding to the coordinates P2 to P17 in the transport direction (X direction) of the printed board 1 is located. Do. That is, at the imaging timing t1, image data in the range of the coordinates P2 to P17 on the printed circuit board 1 on which the fringe pattern is projected is acquired.

Specifically, at the imaging timing t1, the phase of the fringe pattern projected onto the printed circuit board 1 is “0 °” at coordinate P17, “22.5 °” at coordinate P16, “45 °” at coordinate P15,. Image data is acquired in which the phase of the fringe pattern is shifted by 22.5 ° for each of the coordinates P2 to P17, such as "360 ° (0 °)" at the coordinate P1. However, the phase of the fringe pattern shown in FIGS. 7 and 8 is assumed to be projected on a reference position (for example, a background area of the printed circuit board 1) having a height position “0” and a plane.

At an imaging timing t2 at which a predetermined time Δt has elapsed from the imaging timing t1, a range corresponding to the coordinates P6 to P21 on the printed circuit board 1 is located within the imaging range W of the camera 15, and image data of the range is acquired. Ru.

At an imaging timing t3 at which a predetermined time Δt has elapsed from an imaging timing t2, a range corresponding to coordinates P10 to P25 on the printed circuit board 1 is located within the imaging range W of the camera 15, and image data of the range is acquired Ru.

At an imaging timing t4 at which a predetermined time Δt has elapsed from an imaging timing t3, a range corresponding to coordinates P14 to P29 on the printed circuit board 1 is located within the imaging range W of the camera 15, and image data of the range is acquired. Ru.

Thereafter, every time the predetermined time Δt elapses, the same process as the process of the imaging timings t1 to t4 is repeatedly performed.

In this manner, when all data related to a predetermined coordinate position (for example, coordinate P17) on the printed circuit board 1 is acquired, the coordinate positions of the respective image data are aligned (coordinates between the respective image data) System alignment is performed (see FIG. 9). FIG. 9 is a table schematically showing a state in which coordinate positions of a plurality of image data acquired at imaging timings t1 to t4 are aligned.

Subsequently, data relating to the same coordinate position of a plurality of image data is put together for each coordinate position and stored in the calculation result storage device 45 (see FIG. 10). FIG. 10 is a table schematically showing a state in which data relating to each coordinate position on the printed circuit board 1 is organized. However, in FIG. 10, only the part related to the coordinate P17 on the printed circuit board 1 is illustrated.

Thus, in the present embodiment, at each coordinate position on the printed circuit board 1, four different (θ + 0, θ + 90 °, θ + 180 °, θ + 270 °) luminance values are obtained in which the phase of the stripe pattern is shifted by 90 °. It becomes.

Next, the control device 16 measures the height of each coordinate by the phase shift method based on the four types of image data (four luminance values of each coordinate) acquired as described above. The control device 16 calculates height data at each coordinate of the entire printed circuit board 1 by repeating the process for each coordinate, and stores this in the calculation result storage unit 45 as a three-dimensional measurement result of the printed circuit board 1. .

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

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

And if the said Formula (1), (2), (3), (4) is solved about phase (theta), a following formula (5) can be derived.

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

The control device 16 determines the quality of the printed state of the cream solder 4 based on the three-dimensional measurement result (height data at each coordinate) obtained as described above. Specifically, the control device 16 detects a solder print area that is higher than a height reference surface by a predetermined length or more, and integrates the height of each portion in this area to print the printed cream solder 4 Calculate the amount of

Subsequently, the control device 16 sets the data such as the position, area, height or amount of the cream solder 4 thus obtained as reference data (gerber data etc.) stored in advance in the setting data storage device 46. The comparison determination is made, and the quality of the printed state of the cream solder 4 is determined depending on whether the comparison result is within the allowable range.

As described above in detail, according to the present embodiment, a stripe pattern is projected onto the print substrate 1 which is continuously transported, and the printed substrate 1 onto which the stripe pattern is projected is a predetermined amount (90 degrees of the stripe pattern). Every time it is transported). As a result, four types of image data are acquired in which the phases of the projected fringe patterns differ by a predetermined amount (90 ° each). And three-dimensional measurement of the printed circuit board 1 by the phase shift method is performed based on these image data. As a result, it is possible to perform three-dimensional measurement while continuously moving the printed circuit board 1 without stopping the printed circuit board 1. Therefore, it is possible to improve the measurement efficiency, and hence the production efficiency.

Further, the projection device 14 according to the present embodiment is set such that the exit surface (grating surface) 21 b of the grid plate 21 and the main surface of the projection lens unit 19 satisfy the condition of shine proof with respect to the printed board 1. There is. That is, the plane S1 including the emission surface 21b of the lattice plate 21, the plane S2 including the main surface of the projection lens unit 19, and the plane S3 including the surface (projection plane) of the printed board 1 intersect on the same straight line C It is set to. As a result, the fringe pattern can be projected in focus on the entire projection range on the printed circuit board 1. As a result, the measurement accuracy of three-dimensional measurement can be improved.

Furthermore, the pattern generation unit 18 according to the present embodiment is made of an optical material having a predetermined refractive index, and is provided with a grating plate 21 provided with a grating 25 for converting incident light into a fringe pattern; The incident angle adjusting plate 22 disposed on the incident surface 21a side of the grating plate 21 and the same refraction as the grating plate 21 are made of the same material having the same refractive index and the incident angle of incident light is 0 °. The refracting angle adjusting plate 23 is disposed on the side of the exit surface 21b of the grating plate 21 so that the refracting angle of the emitted light is 0 °.

As a result, it is possible to suppress the dispersion or the like of light transmitted through the pattern generation unit 18 and to suppress the blurring or the like of the fringe pattern. As a result, it is possible to improve the measurement accuracy of three-dimensional measurement using the phase shift method.

In addition, according to the present embodiment, the pattern generation unit 18 can be manufactured using an inexpensive light transmitting member such as the existing grid plate 21 in which the grid 25 is printed on a glass plate, for example. Therefore, the manufacturing cost of the projection device 14 can be suppressed as compared with the case where an expensive optical control element such as a DMD is used as the pattern generation unit.

Further, as in the case of using an optical control element such as DMD, there is no need to control the pixel, and the control can be simplified, and the pattern light generated becomes microscopically discontinuous. Since it does not happen, it is possible to project a more ideal fringe pattern on the printed circuit board 1.

Furthermore, as in the case of using an optical control element such as DMD, the generated fringe pattern does not depend on the pixel pitch of the optical control element, and a fringe pattern more suitable for the printed circuit board 1 can be projected.

When the printed circuit board 1 is conveyed by the conveyor 13, the height position may be slightly changed. On the other hand, in the present embodiment, since the projection lens unit 19 is configured by the both-side telecentric lens (both-side telecentric optical system), the fringe pattern is accurately projected without being affected by the height change of the printed circuit board 1 can do.

In addition, it is not limited to the description content of the said embodiment, For example, you may implement as follows. Of course, other applications and modifications not illustrated below are naturally possible.

(A) In the above embodiment, the projection device and the three-dimensional measurement device according to the present invention are embodied in the substrate inspection device 10 for inspecting the printing state of the cream solder 4 printed on the printed substrate 1. For example, the present invention may be embodied in an apparatus for inspecting other objects such as solder bumps formed on a wafer substrate, an adhesive applied on a print substrate, electronic components mounted on a print substrate, and the like. Of course, three-dimensional measurement may be performed with an object different from the substrate as an object to be measured.

(B) In the above embodiment, when performing three-dimensional measurement by the phase shift method, four types of image data in which the phase of the fringe pattern differs by 90 ° are acquired, but the number of phase shifts and the phase shift The amount is not limited to these. Another phase shift number and phase shift amount 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 kinds of image data whose phases are different by 120 ° or 90 °.

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

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

(D) In the above embodiment, the fringe pattern is projected onto the printed circuit board 1 and three-dimensional measurement is performed by the phase shift method. However, the present invention is not limited to this. The three-dimensional measurement may be performed using the pattern projection method of However, when measuring a small measurement object such as the cream solder 4, it is more preferable to adopt a measurement method with high measurement accuracy such as a phase shift method.

(E) In the above embodiment, the positional relationship between the stripe pattern to be projected and the printed substrate 1 is relatively moved by continuously moving the printed substrate 1 by the conveyor 13. However, the stripe pattern and the printed substrate The configuration (displacement means) to move 1 relative to each other is not limited to the above embodiment.

For example, by configuring the measuring head including the projection device 14 and the camera 15 to be movable, the positional relationship between the printed circuit board 1 fixed at the predetermined position and the stripe pattern to be projected may be relatively moved.

Further, by providing the pattern generation unit 18 in the projection device 14 so as to be displaceable, the measurement head comprising the projection device 14 and the camera 15 and the printed circuit board 1 are fixed at a predetermined position in a stopped state without relative movement. The positional relationship between the printed circuit board 1 and the stripe pattern to be projected may be relatively moved.

(F) In the above embodiment, the light source 17 is configured of a halogen lamp that emits white light. Not limited to this, another light source such as a white LED may be used.

(G) The configuration of the pattern generation unit 18 is not limited to the above embodiment. For example, although the grating plate 21 according to the above embodiment has the configuration in which the grating 25 is provided on the emission surface 21b, the present invention is not limited thereto. For example, the grating 25 may be provided on the incidence surface 21a.

In the above embodiment, the grid 25 is provided by printing (vapor deposition). However, the present invention is not limited to this. For example, the grid 25 may be provided by another method such as laser processing.

Moreover, although the grating | lattice 25 which concerns on the said embodiment becomes a binary structure which the light transmission part 25a and the light-shielding part 25b are located in a line by turns, it does not restrict to this, for example, many transmissivitys differ in three or more steps. It may be configured to be provided with a value grid pattern.

In the above embodiment, although the grating plate 21, the incident angle adjustment plate 22 and the refraction angle adjustment plate 23 are formed of the same optical material having the same refractive index, the present invention is not limited to this. 21, at least one of the incident angle adjusting plate 22 and the refractive angle adjusting plate 23 may be formed of different optical materials having the same refractive index.

For example, the first light transmitting member provided with a predetermined grid may be formed of a thin film member or the like. Since the first light transmitting member is configured to be sandwiched by the incident angle adjusting plate 22 and the refraction angle adjusting plate 23, it is possible to suppress the bending of the first light transmitting member.

(H) The projection optical system is not limited to the projection lens unit 19 of the above embodiment. For example, in the above embodiment, the projection lens unit 19 is configured by 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 projection lens unit 19. Moreover, it is good also as a structure which does not have a telecentric structure.

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

Further, the imaging lens unit 15 b is configured by 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. Moreover, it is good also as a structure which does not have a telecentric structure.

(J) Although not particularly mentioned in the above embodiment, the condition of the above-mentioned shine proof is the exit surface 21b (grating 25) of the grating plate 21 in the traveling direction (the direction of the optical axis J1) of the light passing through the pattern generating unit 18. And the exit surface 23b of the refraction angle adjustment plate 23 are preferably added.

The optical path length from the exit surface 21 b of the grating plate 21 to the exit surface 23 b of the refraction angle adjustment plate 23 in the traveling direction of light transmitted through the pattern generation unit 18 is the exit of the grating plate 21 with respect to the exit surface 23 b of the refraction angle adjustment plate 23 It depends on which position on the exit surface 21b in the inclination direction of the surface 21b the light passes.

An optical material such as glass constituting the pattern generation unit 18 usually has a predetermined refractive index higher than the refractive index of air. Therefore, the optical path length of the light traveling in the pattern generation unit 18 is optically longer than the optical path length of the light traveling in the air. Therefore, when the physical length (optical path length) from the exit surface 21b of the grating plate 21 to the exit surface 23b of the refraction angle adjustment plate 23 is different, the optics from the exit surface 21b of the grating plate 21 to the printed board 1 Light path length will be different. In the case where the exit surface 21b of the grating plate 21 and the main surface of the projection lens unit 19 are arranged so as to satisfy the condition of the shine proof without taking this into consideration, slight errors may occur.

On the other hand, if the light emitting surface 21b of the grating plate 21 and the main surface of the projection lens unit 19 are arranged so as to satisfy the condition of the shine proof in a state where the above errors are corrected, the stripe pattern is combined more accurately. You can burn it.

DESCRIPTION OF SYMBOLS 1 ... Printed circuit board, 4 ... Cream solder, 10 ... Board | substrate inspection apparatus, 13 ... Conveyor, 14 ... Projection apparatus, 15 ... Camera, 16 ... Control apparatus, 17 ... Light source, 18 ... Pattern generation part, 19 ... Projection lens unit, Reference Signs List 21 lattice plate 22 incident angle adjusting plate 23 refraction angle adjusting plate 25 lattice 25 a light transmitting portion 25 b light shielding portion 31 incident side lens 32 aperture stop 33 emission side lens , J1 ... light axis.

Claims

It is a projection device which projects predetermined pattern light onto the object to be measured when performing three-dimensional measurement related to the predetermined object to be measured,
A light source that emits a predetermined light;
A pattern generation unit that converts light incident from the light source into the pattern light and emits the light;
A projection optical system for forming an image of the pattern light emitted from the pattern generation unit on the object to be measured;
The pattern generation unit
A first light transmitting member made of an optical material having a predetermined refractive index and provided with a predetermined grating for converting incident light into the pattern light;
It is made of a material having the same refractive index as the first light transmitting member, and is disposed on the light incident surface side of the first light transmitting member so that the incident angle of light incident on the pattern generating unit is 0 °. A second light transmitting member,
It is made of a material having the same refractive index as the first light transmitting member, and is disposed on the light emitting surface side of the first light transmitting member so that the refraction angle of light emitted from the pattern generation unit is 0 °. Composed of a third light transmitting member,
1. A projector according to claim 1, wherein the grating of the first light transmitting member and the main surface of the projection optical system are arranged with respect to the object to be measured such that the conditions of the shine proof are satisfied.
The condition of the shine proof is that the difference in the optical path length from the grating of the first light transmitting member to the light emitting surface of the third light transmitting member in the traveling direction of light transmitted through the pattern generation unit is taken into consideration. The projection device according to claim 1, characterized in that
The projection apparatus according to claim 1, wherein the projection apparatus is configured to be capable of generating pattern light having a stripe-like light intensity distribution as the pattern light.
A projection apparatus according to any one of claims 1 to 3.
An imaging unit capable of imaging a predetermined range of the object to be measured on which the pattern light is projected;
A three-dimensional measuring apparatus comprising: image processing means capable of executing three-dimensional measurement relating to the object based on image data captured and acquired by the imaging means.