JPH08205004A - Image pickup device - Google Patents

Abstract

PURPOSE: To provide an image pickup device in which magnification is selected frequently at a high speed. CONSTITUTION: This image pickup device is provided with a lighting device 40 having 1st and 2nd light sources wit a different wavelength, a dichroic mirror 28 reflecting light obtained by the 2nd light source and transmitting the light with the 1st light source, a 1st lens 32 receiving the light reflected by the dichroic mirror 28, a 2nd lens 34 receiving the light transmitted through the dichroic mirror 28 with a different magnification from that of the 1st lens 32, and an image pickup element 16 picking up image information included in the light transmitted through the 1st lens 32 and the 2nd lens 34. Since any of two kinds of light lighting the image pickup object is selected to make the light including image information of the image pickup object incident on the 1st lens 32 or the 2nd lens 34, the size of the image formed on the image pickup face of the image pickup element 16 is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device used, for example, in an electronic component mounting device for detecting the position of an electronic component and confirming a defect.

[0002]

2. Description of the Related Art Electronic component mounting apparatuses are widely used as means for mounting electronic components such as semiconductor chips and chip resistors on a printed circuit board.

As such an electronic component mounting apparatus, the one described in Japanese Patent Application Laid-Open No. 4-37099 is known. In this device, in order to cope with the miniaturization of electronic components and the shortening of the electronic component mounting time, the electronic components are sucked by a suction nozzle and conveyed onto a printed circuit board. Further, in this electronic component mounting apparatus, an image pickup device that picks up an image of the electronic component is provided in the transport path of the electronic component. By processing the image information obtained by this imaging device, the relative position of the electronic component with respect to the suction nozzle for correcting the position variation of the electronic component with respect to the suction nozzle that occurs at each suction is detected, and the electronic component is detected. It is designed to confirm the absence of defects.

[0004]

In the electronic component mounting apparatus as described above, electronic components of various sizes are generally mounted for reasons such as rationalization of the production process of printed circuit boards. The size of the electronic component is, for example, 1 mm
x0.5mm chip resistance, lead circumference is 24mmx
It varies from 18 mm ICs. In order to image electronic components of various sizes as described above, the magnification of an optical system used in the image pickup apparatus is changed so that an electronic device having an appropriate size is formed on the image pickup surface of the image pickup device incorporated in the image pickup apparatus. It is necessary to form an image of the part.

Therefore, as means for changing the magnification of the optical system used in the image pickup apparatus, there has conventionally been proposed one using a zoom lens or a bifocal switching lens. However, since these means have a structure in which the lens is mechanically moved, there is a problem in durability or operating speed. Particularly in the electronic component mounting apparatus, since it is required to shorten the electronic component mounting time and to have the durability capable of performing the electronic component mounting more than 5 million times, the conventional means using a zoom lens or the like is required. I couldn't handle it enough.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a magnification selectable image pickup apparatus which operates at high speed and has sufficient durability.

[0007]

In order to achieve the above object, an image pickup device according to the present invention emits light of different wavelengths to illuminate an image pickup object placed at a predetermined image pickup position. 2 light source and an imaging target obtained by illuminating the imaging target with the first light source and transmitting light including image information of the imaging target obtained with the second light source A dichroic mirror that reflects light containing image information of an object, a first lens on which the light reflected by this dichroic mirror is incident, and light that has passed through the dichroic mirror is incident, and a magnification different from that of the first lens Is provided, and an image pickup means for picking up image information included in the light transmitted through the first lens and the second lens.

Further, the image pickup apparatus is composed of one image pickup device, the first image pickup device arranged on the optical axis of the first lens, and the first image pickup device arranged on the optical axis of the second lens. And a second image pickup device.

[0009]

According to the above construction, by causing either the first light source or the second light source to emit light, the light containing the image information of the image pickup object is passed through either the first lens or the second lens. It is incident. Since the first lens and the second lens have different magnifications, the size of the image of the object to be imaged is changed by selecting a light source to emit light and selecting a lens on which light is incident.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of an image pickup apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an image pickup apparatus according to the first embodiment of the present invention. The image pickup apparatus 10 in this embodiment is used in an electronic component mounting apparatus (the entire configuration of which is not shown) as described in the above-mentioned Japanese Patent Laid-Open No. 4-37099, and in FIG. Is
The suction nozzle for sucking and conveying the electronic component 14 which is an imaging target is shown. The suction nozzle 12 picks up the electronic component 14 from the component supply unit and conveys it to the printed circuit board, but is temporarily stopped at a predetermined image pickup position during the conveyance. Below the suction nozzle 12 stopped at the imaging position, the imaging device 10 is arranged as shown in FIG.
An image of the electronic component 14 is taken.

In FIG. 1, reference numeral 16 indicates a CCD (charge coupled device) type solid-state image pickup device (hereinafter referred to as "image pickup device") as an image pickup means, and reference numeral 18 indicates an electronic component on an image pickup surface 20 of the image pickup device 16. The optical system for forming 14 images is shown. The optical system 18 in this embodiment, as shown in the figure, includes first, second and third reflecting mirrors 22, 24,
26, and the first and second dichroic mirrors 28, 3
0 and the first and second lenses 3 having different magnifications
2, 34, and these members and the image pickup device 16 are held by a holder 36 that constitutes a dark box.

The holder 36 is provided with an opening 38 for guiding the light including the image information of the electronic component 14 which is an image pickup object to the optical system 18. A lighting device 40 that illuminates the electronic component 14 stopped at the imaging position is arranged in the opening 38. The illumination device 40 includes at least one red light emitting element (first light source; hereinafter referred to as “red LED”) that emits red light (wavelength 660 nm in this embodiment) 4
2 and a near infrared light emitting element (second light source, which emits near infrared light (wavelength 850 nm in this embodiment).
D ”) 44. In this embodiment, as will be described below, since the red LED 42 is for small electronic components, the one that illuminates locally with high illuminance with a narrow irradiation angle is used, and the near-infrared LED 44 is for large electronic components. Therefore, the one that uniformly illuminates a wide irradiation angle is used. Two types of LE used in the lighting device 40
It is preferable that the wavelengths of D42 and D44 are sufficiently separated. FIG. 2 is a diagram showing the relationship between the emission wavelength and the output intensity of the red LED 42 and the near infrared LED 44 in this embodiment.

More specifically, the red LED 42 and the near-infrared LED 44 of the lighting device 40 are provided in the opening 38 so that the direction of the illumination light is directed toward the electronic component 14 sucked by the suction nozzle 12. It is fixed to an annular base 46 attached to the inner wall surface of the adjacent holder 36. In addition, these LEDs 42 and 44 are connected to the annular base 4
6 are staggered along the circumferential direction.

The red LED 42 and the near-infrared LED 44 are connected to a control unit (not shown) of the electronic component mounting apparatus, and either one is controlled so that only one emits light. Here, how the light from the electronic component travels when the red LED 42 or the near-infrared LED 44 is emitted will be described, but the arrangement configuration of each element of the optical system 18 and the image pickup device 16 is further clarified by this. Would.

First, when the red LED 42 is caused to emit light with the suction nozzle 12 sucking the electronic component 14 stopped at a predetermined image pickup position, the red light from the red LED 42 illuminates the electronic component 14, and Electronic component 14
The reflected light from travels along the axis A1. This light is holder 3
The reflected light is reflected by the first reflecting mirror 22 held in the holder 36 through the opening 38 of No. 6. This reflector 22
Since the reflecting surface of the first reflecting mirror 22 is placed at an angle of 45 degrees with respect to the axis A1, the light reflected by the first reflecting mirror 22 travels along the axis A2 orthogonal to the axis A1. A2
The light is incident on the first dichroic mirror 28 arranged above.

The first dichroic mirror 28 has a characteristic of selectively transmitting or reflecting the incident light according to the wavelength of the incident light. FIG. 3 shows the characteristics of the first dichroic mirror 28 used in this embodiment,
As can be seen from this figure, the first dichroic mirror 28 has a wavelength of an inflection point (point at which reflectance or transmittance is 50%) PI1, that is, 750 nm, as a boundary, and an incident wavelength shorter than this wavelength. It has the property of reflecting light and transmitting incident light of long wavelength. Especially wavelength 660nm
Most of the incident light is reflected, and the wavelength of 850n
Most of the incident light of m is transmitted. Therefore, axis A
The red light (660 nm) traveling along 2 is reflected by the first dichroic mirror 28 and guided upward along an axis A3 extending at a right angle to the axis A2.

A first lens 32 is arranged above the first dichroic mirror 28 so that its optical axis substantially coincides with the axis A3. In this embodiment, the first lens 32 has a high magnification. Further, the illustrated first lens 32 is composed of a plurality of lenses for the purpose of correcting chromatic aberration, but may be composed of a single lens. The light reflected by the first dichroic mirror 28 passes through the first lens 32 and then further travels upward along the axis A3.

A second dichroic mirror 30 is arranged above the first lens 32 and on the axis A3. The second dichroic mirror 30 has the characteristics shown in FIG. 4 with respect to the incident light, and transmits the incident light having a wavelength shorter than the wavelength (750 nm) of the inflection point PI2.
Therefore, the red light (660n) incident along the axis A3 is
Most of m) is transmitted through the second dichroic mirror 30, goes straight, and is incident on the imaging surface 20 of the imaging element 16.

An image of the electronic component 14 is formed on the image pickup surface 20 of the image pickup device 16 by the first lens 32. In this case, since the first lens 32 has high magnification, the image of the electronic component 14 is enlarged and formed. When the image of the electronic component 14 is formed on the image pickup surface 20 in this way, the image pickup device 16 converts the information of the optical system into an electric image information signal, and the control unit (FIG. Output (not shown). In the control unit, it is possible to appropriately process this image signal and perform position detection and loss confirmation.

On the other hand, when the near-infrared LED 44 is caused to emit light, the near-infrared light from the near-infrared LED 44 illuminates the electronic component 14 as in the case of the above-mentioned red light, and the electronic component 1
The reflected light from 4 is reflected by the first reflecting mirror 22 and then travels along the axis A2 to produce the first dichroic mirror 2
It is incident on 8.

Since the wavelength of the near infrared light incident on the first dichroic mirror 28 is 850 nm, most of the incident light is transmitted through the first dichroic mirror 28 as understood from FIG. Go straight.

The near infrared light transmitted through the first dichroic mirror 28 is reflected by the second reflecting mirror 24 arranged on the axis A3.
Reflected by and travels along an axis A4 orthogonal to the axis A2. The reflecting mirror 24 is installed so that the axis A4 and the axis A3 are substantially parallel to each other.

A second lens 34 is arranged above the second reflecting mirror 24 so that its optical axis substantially coincides with the axis A4. The second lens 34 has a magnification lower than that of the first lens 32. Although the illustrated second lens 34 is composed of a plurality of lenses, it may be composed of a single lens like the first lens 32.

The light transmitted through the second lens 34 further travels upward along the axis A4, is then reflected by the third reflecting mirror 26, and travels along the axis A5 orthogonal to the axis A4.
The reflector 26 is positioned such that the axis A5 is substantially parallel to the axis A2 and intersects the axis A3 on the reflecting surface of the second dichroic mirror 30.

The near-infrared light traveling along the axis A5 is incident on the second dichroic mirror 30. In this case, as understood from FIG. 4, most of the incident near-infrared light is reflected by the second dichroic mirror 30. Then, the reflected near-infrared light travels along the axis A3 and is incident on the imaging surface 20 of the imaging element 16.

When the near infrared light is incident on the image pickup surface 20 of the image pickup device 16 in this manner, an image of the electronic component 14 is formed on the image pickup surface 20 by the second lens 34.
Since the second lens 34 has a lower magnification than that of the first lens 32, when an electronic component having the same size is imaged, the image by the near infrared light is smaller than the image by the red light.

FIG. 5 is a diagram showing the sensitivity of the CCD type image pickup device 16 in this embodiment to the light receiving wavelength.
When the image sensor 16 having the characteristics shown in this figure is used,
The light receiving sensitivity is sufficient for the above-described red light having a wavelength of 660 nm and near infrared light having a wavelength of 850 nm, and imaging can be performed without any trouble.

The image pickup apparatus 10 having the above-mentioned configuration can be used in various modes as a part of the inspection apparatus in the electronic component mounting apparatus, one of which will be described.

First, the control unit of the electronic component mounting apparatus controls the drive unit to move the suction nozzle 12 onto the component supply unit, and the electronic component 14 to be mounted by the suction nozzle 12 is mounted.
Adsorb. Next, the suction nozzle 12 is moved to the image pickup position while the electronic component 14 is suctioned, and is temporarily stopped there. This state is the state shown in FIG.

Since the control unit has already recognized the type and external dimensions of the sucked electronic component 14, the electronic component 14
When is placed in the image pickup position, the red LED 42 or the near infrared LED 44 is caused to emit light according to the external dimension thereof. That is, when the electronic component 14 is a minute chip resistor or the like, the red LED 42 is caused to emit light, and when the electronic component 14 is a relatively large IC or the like, the near infrared LED 44 is caused to emit light.

As described above, when the red LED 42 is caused to emit light, the light including the image information of the electronic component 14 is reflected by the axis A.
1, proceeds along the axis A2 and the axis A3 and enters the image pickup surface 20 of the image pickup device 16, and the image of the electronic component 14 is magnified by the first lens 32 and is formed on the image pickup surface 20. Since the image of the electronic component 14 is enlarged in this way, the electronic component 1
When the size of 4 is small, the imaging surface 20 of the imaging device 16
An image having a size suitable for image processing can be formed thereon.

When the near-infrared LED 44 is caused to emit light, the light from the electronic component 14 has axes A1, A2 and A2.
4, goes along the axis A5 and the axis A3 and is incident on the image pickup surface 20 of the image pickup element 16, and the image of the electronic component 14 is transferred to the second lens 3
An image is formed on the image pickup surface 20 by 4. Since the image of the electronic component 14 formed by the second lens 34 is smaller than the image formed by the first lens 32, the image of the relatively large electronic component 14 is properly projected on the image pickup surface 20 of the image pickup element 16.

The optical image formed on the image pickup surface 20 of the image pickup device 16 is inputted to the control section of the electronic component mounting apparatus as an electric image information signal. The control unit performs image processing based on this signal, detects the relative position of the electronic component 14 with respect to the suction nozzle 12, and confirms whether the electronic component 14 is defective. After that, the control unit controls the drive unit to move the suction nozzle 12 onto the printed board, arrange the electronic component 14 at a predetermined mounting position on the printed board, and then release the suction by the suction nozzle 12. At this time, the positional deviation of the electronic component 14 with respect to the suction nozzle 12 is corrected by the control unit controlling the driving unit by the correction signal based on the relative position of the electronic component 14 described above. When it is determined that the electronic component 14 is not sucked, the suction nozzle 12 is returned to the component supply unit again, and the same process is repeated.

Although the suction nozzle 12 is temporarily stopped at the image pickup position in the above, the red LED is not stopped at the moment the image pickup position is passed without stopping.
It is also possible to image the adsorbed electronic component 14 by causing the 42 or the near-infrared LED 44 to emit a strobe light. In this case, there is an advantage that the time required for the carrying process and the imaging process is shortened, and the mounting efficiency is improved.

In the image pickup apparatus 10 of the above embodiment, only one image pickup element 16 is provided as the image pickup means, but two image pickup elements are provided as in the image pickup apparatus 100 according to the second embodiment shown in FIG. Is also possible. In the image pickup apparatus 100 according to the second embodiment, the third reflecting mirror 26 and the second dichroic mirror 30 in the image pickup apparatus 10 according to the first embodiment are not provided, and the second image pickup element 50 is provided.
However, the imaging surface 52 is on the axis A4 and the second lens 3
It is attached to the holder 54 so as to be arranged at the image point position of No. 4. Since the other points are substantially the same as those of the first embodiment, the same or corresponding portions will be denoted by the same reference numerals, and detailed description thereof will be omitted.

In this image pickup device, when the red LED 42 is caused to emit light, the red light from the electronic component 14 travels along the axis A1, the axis A2, and the axis A3, as in the case of the first embodiment. The light is incident on the image pickup surface 20 of the first image pickup device 16.
Therefore, the image of the electronic component 14 is formed on the imaging surface 20 of the first imaging element 16 by the first lens 32.

When the near-infrared LED 44 emits light, it travels along the axis A1 and the axis A2, passes through the dichroic mirror 28, is reflected by the second reflecting mirror 24, and enters the second lens 34. What is done is the same as in the first embodiment. However, after passing through the second lens 34, the light enters the image pickup surface 54 of the second image pickup element 52 as it is. Of course, in this case as well, the image of the electronic component 14 formed on the image pickup surface 54 of the second image pickup element 52 is obtained by the second lens 34, and thus is smaller than the image obtained by the first lens 32. Will be formed.

When such an image pickup apparatus 100 is used in an electronic component mounting apparatus, the first and second image pickup elements 1
The output signals from 6 and 50 are respectively input to the control unit of the electronic component mounting apparatus, image processing is appropriately performed, and position detection and loss confirmation are performed.

Although the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-mentioned first and second embodiments. For example, in the above embodiment, a red LED emitting a red light having a wavelength of 660 nm and a wavelength of 8
A near-infrared LED that emits near-infrared light of 50 nm is used, but it is sufficient if there are two light sources that can illuminate with light of different wavelengths, and the emission wavelength is appropriately selected according to the light receiving sensitivity of the image sensor and the characteristics of the dichroic mirror. Can be done. Therefore, light sources having different wavelengths may be selected and combined. (By selecting and combining light sources having different wavelengths, an illuminating device equivalent to the illuminating device according to the present invention can be constructed.) Further, the positions and the numbers of the red LEDs and the near-infrared LEDs of the illustrated embodiment are also shown. Not limited to things. For example, these LEDs may be arranged behind the imaging target to capture a silhouette image (or silhouette video) of the imaging target.

Further, as the image pickup means, in addition to the CCD type solid-state image pickup element, various image pickup devices such as a solid-state image pickup element of another type such as a MOS type or a phototube type image pickup tube may be used. it can.

In the above embodiment, the first lens is a high-magnification lens and the second lens is a low-magnification lens.
You may reverse this. In such a case, the image obtained using red light is projected at a low magnification, so infrared light is irradiated on large electronic components, and conversely, near infrared light is irradiated on small electronic components. Will be done.

Furthermore, the object to which the image pickup apparatus according to the present invention is applied is not limited to the electronic component mounting apparatus, but can be applied to other apparatuses and systems such as a semiconductor manufacturing system.

[0044]

As described above, according to the present invention, by selecting two kinds of illumination light that illuminates the object to be imaged, the first lens having different magnifications for the light including the image information of the object to be imaged. Alternatively, since the light can be made incident on either of the second lenses, the size of the image formed on the image pickup surface of the image pickup device can be changed. Therefore, it is not necessary to use an optical system having a mechanical driving unit such as a bifocal lens to change the size of the image. This has many effects as shown below.

(1) Since it has no mechanical drive,
Durability is improved and high speed operation is possible. Also, the structure is simplified.

(2) The decrease in the amount of light by the dichroic mirror is slight, and the decrease in the amount of light in the optical system of the image pickup apparatus using such a dichroic mirror is small.
Therefore, the number of lamps used for the light source can be reduced, and the power consumption required for illumination can be reduced. In addition, by flashing such a light source, it is possible to capture an image of a moving image capturing object.

(3) As described above, since the decrease in the amount of light in the optical system of the image pickup device is small, the S / N ratio which is the ratio of the video signal to the noise peculiar to the image pickup device is improved, and the reliability of the device is improved. Can be made.

(4) Since the dichroic mirror slightly reduces the amount of light, the image pickup apparatus can be constructed even when a lens having a relatively large F value is used. F of the lens
Since the depth of field can be deepened by increasing the value, it is possible to obtain a clear image without blurring on the image pickup surface of the image pickup device even if the distance to the image pickup target changes to some extent.

(5) Since the F value of the lens can be increased,
The image pickup device can be configured by using a lens having a small aperture.
In this case, since the light beam in the optical system becomes thin, not only the lens but also the components of the optical system such as the dichroic mirror and the reflecting mirror can be downsized, and the entire image pickup apparatus can be downsized. By reducing the size of the components of the optical system, the cost of the entire image pickup apparatus can be reduced.

Further, in the image pickup apparatus according to the present invention, since only one of the two types of light sources emits light, the life of each light source is extended.

Further, as described above, when only one image pickup device is used as the image pickup means, the cost can be reduced.

As described above, since the image pickup apparatus according to the present invention is excellent in durability and high speed, it can be effectively used as a part of the inspection apparatus in the electronic component mounting apparatus which has a large number of inspections and a high operation speed. is there.

[Brief description of drawings]

FIG. 1 is a diagram showing an image pickup apparatus according to the present invention and showing an embodiment using one image pickup element.

FIG. 2 is a diagram showing a relationship between a light emission wavelength and an output intensity of a lighting device in an image pickup device according to the present invention.

FIG. 3 is a diagram showing characteristics of a first dichroic mirror in the image pickup device according to the present invention.

FIG. 4 is a diagram showing characteristics of a second dichroic mirror in the image pickup device according to the present invention.

FIG. 5 is a diagram showing the sensitivity of an image pickup element in the image pickup apparatus according to the present invention to a light receiving wavelength.

FIG. 6 is a diagram showing an image pickup apparatus according to the present invention and showing a second embodiment using two image pickup elements.

[Explanation of symbols]

10 ... Imaging device, 12 ... Suction nozzle, 14 ... Electronic component,
16 ... Image sensor, 22, 24, 26 ... Reflector, 28, 3
0 ... Dichroic mirror, 32, 34 ... Lens, 40
... illuminating device, 42 ... infrared LED, 44 ... near infrared LED.

Claims (3)

[Claims] 1. A first light source and a second light source which emit light of different wavelengths and illuminate an imaging object arranged at a predetermined imaging position, and illuminate the imaging object by the first light source. Transmitting the light including the obtained image information of the imaging object, and
A dichroic mirror that reflects light including image information of the imaging target obtained by illuminating the imaging target with the second light source; and a first lens on which the light reflected by the dichroic mirror is incident. A second lens having a magnification different from that of the first lens when the light transmitted through the dichroic mirror is incident, and an image included in the light transmitted through the first lens and the second lens. An image pickup device comprising: an image pickup unit that picks up information. 2. The image pickup apparatus according to claim 1, wherein the image pickup means includes one image pickup device. 3. The image pickup means includes a first image pickup device arranged on the optical axis of the first lens and a second image pickup device arranged on the optical axis of the second lens. The imaging device according to claim 1, wherein the imaging device comprises: