JPH08254500A - Appearance inspection device - Google Patents

Abstract

PURPOSE: To provide an appearance inspection device for the mounted condition of component parts on a printed circuit board, with which it is possible to draw out easily the contour of even an object bearing a similar color to the ground color or an object to be hidden behind the shade of a tall component and can perform a precision inspection while the configuration remains simple. CONSTITUTION: A CCD line sensor 2 is installed as a photographing element, and a frame 7 to support this sensor 2 and lighting systems 5, 6 is moved along a scanning guide 8 so that a printed circuit board 1 as object to be inspected is scanned, and the image of the board 1 is displayed on a monitor screen. At this time, the first lighting system 5 illuminates the board 1 so that the direction of the illuminating light to the board 1 is identical to the direction of the reflected light by the board 1 advancing to the line sensor 2, and the first image is produced. Then the second illuminating means 6 illuminates the board 1 so that the direction of the illuminating light differs from the direction of the reflected light advancing to the line sensor 2, and the second image is produced. From these images, the inspection of the component mounted condition on the board 1 can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual inspection apparatus suitable for inspecting the mounting state of electronic circuit components on a printed circuit board.

[0002]

2. Description of the Related Art Conventionally, for example, as an inspection device for inspecting the mounting state of electronic components on a printed circuit board, the printed circuit board is scanned by an image pickup device, and an image obtained as a result has a specific brightness region or a specific color. There are known methods for extracting various areas and performing various inspections. A typical example of this is to extract a gray area on the substrate and inspect the area and spread of the cream solder applied to the copper foil portion on the substrate.

In addition, the quality of a product is also checked by inspecting the displacement or inclination of the mounting position of the component on the board by the same imaging method as described above. The inspection method in this case is
Unlike the case of the cream solder described above, the area of the same color as the color of the substrate stored in advance is excluded from the read image, and the remaining area is recognized as a component.

FIG. 11 is a diagram showing an outline of an image pickup system in the conventional visual inspection apparatus as described above. In the figure, 101
Is an object to be inspected such as a printed circuit board, and the object to be inspected 101 is illuminated from the periphery by, for example, a ring-shaped fluorescent tube 102, and the reflected light is made incident on an image sensor 104 such as a CCD through an imaging lens 103. As a result, an image of the inspection object 101 is formed on the light receiving surface of the image sensor 104, and the image light is photoelectrically converted into an electric signal. Then, by processing the image signal converted into the electric signal, the image of the inspection object 101 can be displayed on a monitor (not shown).

The conventional inspection apparatus having the above-mentioned image pickup system is designed to illuminate the inspection object 101 obliquely from the lateral direction and measure the color and brightness of the inspection object 101.
The inspector sees the image displayed on the monitor and inspects the inspection object 10
It is possible to judge the color and brightness of the inspection object in 1 and to know the mounting state of the components on the printed board from the judgment result.

FIG. 12 is a diagram showing the outline of another conventional image pickup system. This image pickup system uses a half mirror 105 to illuminate the object to be inspected 101. The light from the light source 106 is converted into parallel light using a condenser lens 107, and the light is reflected by the half mirror 105. The inspection object 101 is irradiated with the reflected light. Then, the image light reflected by the inspection object 101 passes through the image pickup lens 103, further passes through the half mirror 105, and enters the image sensor 104.

The illumination method of this image pickup system is used as coaxial epi-illumination in a microscope or the like, and with such an illumination method as well, the mounting state of components on a printed circuit board can be inspected.

[0008]

However, in the conventional appearance inspection apparatus as described above, the object to be inspected is illuminated obliquely from the lateral direction, and therefore, the limbs of the object to be inspected are correctly extracted. However, there is a problem in that the inspection cannot be performed with high accuracy.

That is, the color of the object to be inspected in the object to be inspected is often similar to the base color. For example, a white capacitor mounted on a white silk-printed area on a printed circuit board or a base resist color is Black transistors, chip resistors, etc. mounted on a very dark green printed circuit board are very similar to the background color.In such a case, it is possible to extract the outline of the component even if a specific color can be extracted. Can not.

Further, in these methods of extracting the color and brightness of the inspection object, it is necessary to set a large incident angle of the illumination light with respect to the inspection object. The difference cannot be recognized and the contour of the part cannot be extracted. Furthermore, in many cases, the electrode terminals of the solder and the parts on the printed circuit board are of the same metal color, so it is not possible to extract the electrode terminals, so items such as misalignment, bending, and floating of the electrode terminals are not subject to inspection. turn into.

Further, in the apparatus as shown in FIG. 12, the direction of the reflected light on the optical axis is greatly different from the optical axis toward the image sensor, especially at the end portion of the angle of view, that is, the end portion of the object to be inspected.
The amount of incident light on the image sensor is reduced. Therefore, there is a problem in that even the color or brightness of the inspection target cannot be extracted, the contour of the inspection target cannot be extracted, and accurate inspection cannot be performed.

The present invention has been made by paying attention to the above problems, and has a simple structure and does not perform complicated color extraction condition setting processing and the like, and an inspection target of a color similar to the base color is inspected. It is an object of the present invention to provide an appearance inspection device that can accurately and easily extract each contour even when there is a large inspection target having a large height, and can perform highly accurate inspection.

[0013]

The visual inspection apparatus according to the present invention is configured as follows.

(1) An appearance inspection apparatus comprising illumination means for scanning an object to be inspected with an image sensor to inspect its appearance, wherein the illumination means comprises a first illumination means and a second illumination means. Therefore, the first illuminating means illuminates so that the direction of the illumination light that illuminates the inspection object is the same direction as the reflected light that is reflected by the inspection object and is directed to the image pickup device.

(2) A visual inspection apparatus comprising illumination means for scanning an object to be inspected with an image sensor to inspect its appearance, wherein the illumination means comprises a first illumination means and a second illumination means. The first illuminating means illuminates the object to be inspected so that the direction of the illuminating light that illuminates the object to be inspected is the same as the reflected light that is reflected by the object to be inspected and is directed toward the image pickup device. Illumination is performed so that the direction of the illumination light that illuminates the inspection object is different from the direction of the reflected light that is reflected by the inspection object and travels toward the image sensor.

(3) A visual inspection apparatus comprising illumination means for scanning an object to be inspected with an image sensor to inspect its appearance, wherein the illumination means is arranged so that the direction of illumination light for illuminating the object to be inspected. Illumination is performed so as to be in a direction symmetrical to the reflected light reflected by the inspection object and directed to the image pickup device.

(4) A visual inspection apparatus comprising illumination means for scanning an object to be inspected by an image sensor to inspect its appearance, wherein the illumination means comprises first illumination means and second illumination means. The first illuminating means illuminates so that the direction of the illumination light illuminating the inspection object is symmetrical to the direction of the reflection light reflected by the inspection object and traveling toward the image sensor, and the second illuminating means The illumination is performed such that the direction of the illumination light that illuminates the inspection object is different from the direction of the reflected light that is reflected by the inspection object and travels toward the image sensor.

(5) In the appearance inspection apparatus according to any one of (1) to (4) above, the illuminating means comprises a light emitting light source and a light guiding means for aligning the luminous flux from the light emitting source in a predetermined direction.

(6) In the visual inspection apparatus according to any one of (1) to (5) above, the image pickup device is a one-dimensional image sensor.

(7) In the visual inspection apparatus according to any one of (1) to (5) above, the image pickup device is a two-dimensional image sensor.

[0021]

According to the present invention, the object to be inspected is illuminated so that the direction of the illumination light for illuminating the object to be inspected is the same as the direction of the reflected light reflected by the object to be inspected and traveling toward the image pickup device. A portion where a step is generated in the height of the inspection object is dark, and a flat portion is imaged brightly, and the contour of the inspection target having unevenness is conspicuously displayed.

Further, since the inspection object is illuminated so that the direction of the illumination light for illuminating the inspection object is symmetrical to the reflected light which is reflected by the inspection object and is directed to the image pickup device, the inspection is performed in the same manner. The outline of the object is displayed prominently.

Further, since the object to be inspected is illuminated so that the direction of the illumination light illuminating the object to be inspected is different from the direction of the reflected light reflected by the object to be inspected and directed to the image pickup device, the object to be inspected is illuminated. Marks on the flat part are also clearly displayed.

[0024]

1 is a perspective view schematically showing the construction of a visual inspection apparatus according to a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a printed circuit board which is an object to be inspected, on which electronic circuit parts such as capacitors and transistors to be inspected are mounted. Reference numeral 2 denotes a CCD line sensor (one-dimensional image sensor) provided as an image sensor for scanning the printed circuit board 1, and photoelectrically converts image light from the printed circuit board 1 which is a subject into an electric signal.
Reference numeral 3 denotes an image pickup lens that makes the image light of the printed board 1 incident on the light receiving surface of the CCD line sensor 2.
The image light reflected by the printed board 1 passes through this lens 3 via the half mirror 4 and enters the CCD line sensor 2.

Reference numeral 5 denotes a linear first illuminating device (illuminating means) for illuminating the printed circuit board 1 from above. The direction of the illumination light is the same as the reflected light reflected by the printed circuit board 1 and directed to the CCD line sensor 2. Illuminate in the direction. In this example, the printed circuit board 1 is illuminated through the half mirror 4.

Reference numerals 6 and 6 denote linear second illuminating devices (illuminating means) for illuminating the printed circuit board 1 obliquely laterally. The direction of the illumination light is reflected by the printed circuit board 1 toward the CCD line sensor 2. Illuminate in a direction different from the reflected light. Two second illuminating devices 6 are provided in this embodiment, but one or three or more second illuminating devices 6 may be provided, and the shape thereof is not limited to the linear one.

Reference numeral 7 denotes a frame which integrally supports the CCD line sensor 2, the image pickup lens 3, the half mirror 4, the first illuminating device 5 and the second illuminating devices 6 and 6, and extends along the scanning guide 8. It is possible to move in the direction of the arrow in the figure. Reference numeral 9 is a drive motor for scanning and moving the frame 7.

2A and 2B show the internal construction of the first illumination device 5, wherein FIG. 2A is a side sectional view and FIG. 2B is a longitudinal sectional front view.

This illuminating device 5 comprises a light emitting source and a light guiding means for aligning the luminous flux from the light emitting source in a predetermined direction. In this embodiment, a plurality of LEDs 12 fixed to the frame 11 are used as the light emitting source. In addition, the condenser lens 13 and the slit array 14 are used as the light guiding means.

The light emitted from the LED 12 enters the condenser lens 13 and is further guided to the slit array 14 from here. At this time, the light emitted from the LED 12 is radial as shown by the arrows in the figure (alternative in the figure), but the lateral direction of the frame 11 is collimated by the collecting lens 13 and the longitudinal direction is Since it is blocked by the partition walls of the slit array 14, the light emitted from the exit of the slit array 14 becomes substantially parallel light.

On the other hand, the second illuminators 6 and 6 have a structure in which the slit array 14 is removed from the illuminator 5 of FIG. 2, and the light from the LED 12 is linearly condensed by the condenser lens 13. However, the longitudinal direction of the frame 11, that is, C
The CD line sensor 2 is not parallelized in the longitudinal direction.

Next, the operation of the appearance inspection apparatus configured as described above will be described.

First, the printed circuit board 1 is mounted in the first lighting device 5.
Is illuminated from directly above, the frame 7 is moved by the drive motor 9 from the start position in FIG. 1 in the arrow direction, and the printed circuit board 1 is scanned. At this time, the image light reflected by the printed circuit board 1 passes through the half mirror 4 and the image pickup lens 3 and then the CCD.
It is incident on the line sensor 2, and the image of the printed circuit board 1 is sequentially formed line by line on the CCD line sensor 2 by the imaging lens 3. The image signal photoelectrically converted by the CCD line sensor 2 is stored in a memory (not shown),
After the image processing, the image is sent to a monitor (not shown), and the image of the printed circuit board 1 is displayed on the monitor as a first plane image.

Next, the drive motor 9 returns the frame 7 to the start position, and the second illuminating devices 6 and 6 illuminate the printed circuit board 1 from the side. Then, similarly to the above, the frame 7 is moved in the direction of the arrow in the figure to scan the printed circuit board 1. As a result, the printed circuit board 1 is placed on the monitor.
Second planar image of is displayed.

As described above, the first plane image and the second plane image of the printed circuit board 1 which are different from each other are obtained, and the inspector observes these images to confirm the mounting state of the components on the printed circuit board 1. Can be inspected.

First, when the first illuminating device 5 illuminates and scans the printed circuit board 1 as shown in FIG. 3, light emitted from the illuminating device 5 passes through the half mirror 4 and passes through the printed circuit board 1. Illuminate linearly. In this embodiment, the incident angle of the illumination light on the printed circuit board 1 at that time is set to 0 degree. Then, the image light reflected by the printed board 1 is reflected by the half mirror 4 and enters the CCD line sensor 2 through the imaging lens 3. The emission angle of the image light reflected and emitted by the printed circuit board 1 at that time is also 0 degree.

Under such illumination of the illuminating device 5, the horizontal plane on the printed circuit board 1 is specularly reflected (total reflection) and brightly observed, while the contour of the mounted component and the inclination with the solder attached thereto. The surface is observed as a dark part (dark line) because the reflected light does not return. The line width of the dark portion of the contour of the component at this time depends on the roundness and taper of the corner of the component, and the line width of the solder portion is proportional to the fillet length.

FIG. 4 shows a read image read by scanning the printed circuit board 1 shown in FIG. 3, where (a) is a read image obtained under conventional illumination and (b) is this embodiment. The read images obtained under the illumination of the illumination device 5 of FIG.

Conventionally, as shown in FIG. 4A, a mark for aligning the printed circuit board 1 and a mark indicating the polarity of a component can be recognized well, but some unrecognizable portions can be recognized. Exists. For example, the polarity mark indicating pin 1 of an IC component cannot be identified because it is hidden by the color of the component body, and capacitors of the same color on the silk-printed pattern area on the board cannot be distinguished. Is difficult to identify. Further, the parts where the solder and the electrode terminals are joined and the lead tips of the IC parts also have no color difference at the same time, and the contours of the parts are unknown, and therefore, the displacement and bending of the electrode terminals cannot be inspected.

Further, a component with a large height is often read as a large size due to the influence of the shadow of the component itself and is often mistakenly recognized. Furthermore, a component with a large height is adjacent to a small component. The light does not reach, making it impossible to distinguish from the underlying resist color. Further, due to manufacturing variations, a component in which the color of the electrode terminals at both ends deviates from the predetermined color extraction range is recognized as having no electrode terminal.

However, in this embodiment, as shown in FIG. 4 (b), the portion where the irregularities change, such as the contour of the component, is dark.
An image with a bright contrast and a strong contrast can be obtained in the flat portion. For this reason, when the background color and the color of the parts, which was difficult in the past, are very similar to each other, when small parts are placed in the shadow of a part with a large height, and the color of the electrode terminals is different from the metal color such as solder. Even in the case of colors of the same system, it is easy to extract those parts and electrode terminals.

On the other hand, when the brightness information such as the mark for the alignment of the printed circuit board 1 and the polar mark cannot be obtained, the conventional illumination / imaging method may be combined with this image. That is, the second illumination device 6, 6 is added to the image.
By combining the images obtained under the above illumination, the above-mentioned marks and the like can be easily recognized, whereby inspection of all inspection items becomes possible.

As described above, even if there is an inspection target of a color similar to the background color or an inspection target of a large height, the contours of each of the outlines can be drawn with a simple structure without performing complicated color extraction condition setting processing. Correct and easy extraction can be performed, and highly accurate inspection can be performed.

In the example of FIG. 1, the output angle of the image light reflected by the printed board 1 and directed to the CCD line sensor 2 from the printed board 1 is set to 0 degree, and the printed board 1
The incident angle of the illumination light from the first illuminating device 5 that is incident on is matched by the half mirror 4, but as shown in FIG.
The printed circuit board 1 may be illuminated without passing through the half mirror 4 by increasing the output angle and the incident angle while keeping the same.

Next, a second embodiment of the present invention will be described. When the angle of view (viewing angle) of the imaging lens 3 is small,
As shown in FIG. 6, it is possible to irradiate the printed circuit board 1 with the parallel light emitted from the illuminating device 5 as it is. The reflected light required for imaging cannot be sufficiently obtained at both ends of the substrate 1.

Therefore, in this embodiment, as shown in FIG.
The slit array 15 of the first lighting device 5 is attached to the frame 11
The partition wall is inclined inward toward the outer side in the longitudinal direction, and the direction of the illumination light emitted from this slit array 15 is symmetrical with respect to the reflected light reflected by the printed circuit board 1 and directed to the CCD line sensor 3 with respect to the substrate surface. I try to illuminate in the direction. The other structure is the same as that of the embodiment shown in FIG.

In this way, the light guide path of the first illuminating device 5 is tilted inward with respect to the longitudinal direction in accordance with the angle of view of the image pickup lens 3 to make the amount of total reflected light incident on the CCD line sensor 2 uniform. Therefore, it is possible to obtain the same effects as those of the above-described embodiment. Further, in the case of this embodiment, it is possible to extract the inclined portion to which the solder is attached,
It is possible to easily inspect the bonding state with solder.

Next, a third embodiment of the present invention will be described. In each of the above-described embodiments, the case where the one-dimensional image sensor is used as the image pickup element has been described, but in the present embodiment, the two-dimensional image sensor is used, and the printed board 1 as the inspection object is divided into a plurality of blocks and scanned. I am trying to do it. FIG. 8 shows an outline of the image pickup system.

In FIG. 8, 16 is a spherical light emitting source, 1
Reference numeral 7 is a lens for making the light from the light source 16 substantially parallel, 18
Is a light guide plate such as a slit array for further collimating the light passing through the lens 17, and the light source 16, the lens 17, and the light guide plate 18 constitute the first illumination device 5. As in the example, the printed circuit board 1 is configured to supply illumination light perpendicular to the substrate surface via the half mirror 19.

The light guide plate 18 may be omitted if the angle of view of the image pickup lens for forming an image of the printed circuit board 1 on a CCD area sensor (two-dimensional image sensor) (not shown) is small. Although not provided, the above-mentioned second illumination device for illuminating the printed circuit board 1 from the side is also provided.

In this way, even when the printed circuit board 1 is scanned for each block area by using the area sensor, the same operation and effect as those of the above-described embodiments can be obtained by the first illumination device 5, and the inspection can be performed. The contour can be easily extracted according to the unevenness of the object, and the mounting component inspection can be performed with high accuracy.

FIG. 9 is a block diagram showing the circuit arrangement of the appearance inspection apparatus in each of the above embodiments. In the figure, 21 is a main CPU that controls the whole, and 22 is a C for image processing.
The PU stores and controls the image signal from the CCD line sensor 2 in the memory 23 and displays the image on the monitor 24.

Reference numeral 25 is a lighting control section for controlling the respective lighting devices 5, 6, 26 is a controller for controlling the X-axis scanning mechanism 27 for moving the frame 7 along the scanning guide 8, and 28 is a conveyor for carrying the printed circuit board 1. 29 for exchanging control signals with each other, and for each interface (I
/ F) I / O (input / output) for exchanging signals with 30
It is a control unit.

FIG. 10 is a flow chart showing an example of the inspection method in the above appearance inspection apparatus.

As described above, first, the printed board 1 is scanned under the illumination of the first illumination device 5 to form the first screen (step S1), and then the illumination of the second illumination devices 6 and 6 is performed. Similarly, a second screen is formed below (step S2). Then, the board mark is extracted from the second screen (step S3), the board set deviation is calculated (step S4), and the board position is determined (step S5).

Next, the printed circuit board 1 is displayed from the first screen.
The contour candidates of the components mounted on the are extracted (step S
6) Then, the contour that matches the shape of the part is extracted.
Then, the component size is determined (step S8), and the mounting position of the component is determined (step S9). Next, the displacement is determined from the mounting position of the component (step S1
0), then the color of the component is extracted from the second screen (step S11), and it is determined whether the component is erroneously mounted (step S1).
2). Further, the polarity mark is extracted from the second screen (step S13), and the polarity determination is performed (step S14).

Next, electrode contour candidates are extracted from the first screen (step S15), contours matching the electrode shape are extracted from them (step S16), and the electrode positions are determined (step S17). Then, the displacement of the electrodes is determined (step S18), the outline of the solder is extracted from the first screen (step S19), the bridge is determined (step S20), and the blowhole is determined (step S).
21), solder floating determination (step S22), and solder amount determination (step S23).

The processing of steps S6 to S23 is performed for each component, and the processing of steps S15 to S23 is performed for each electrode.

[0060]

As described above, according to the present invention, the direction of the illumination light that illuminates the object to be inspected is the same as the reflected light reflected by the object to be inspected and directed toward the image pickup device. Since the object is illuminated, the part with a step in height is dark and the flat part is imaged brightly. With a simple configuration, a color similar to the background color can be obtained without performing complicated color extraction condition setting and other processing. Even if there is an inspection target or an inspection target having a large height, the contours of each can be correctly and easily extracted, and the inspection can be performed with high accuracy.

Further, according to the present invention, the object to be inspected is illuminated so that the direction of the illumination light illuminating the object to be inspected is symmetrical to the direction of the reflected light reflected by the object to be inspected and directed to the image pickup device. Therefore, similarly to the above, the contour of the inspection target is conspicuously displayed, and highly accurate inspection can be performed.

By illuminating the inspection object so that the direction of the illumination light for illuminating the inspection object is different from the direction of the reflected light reflected by the inspection object and traveling toward the image pickup device, the inspection object is illuminated. Marks on the flat part are also clearly displayed.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the internal structure of the first lighting device of FIG.

FIG. 3 is a perspective view showing the appearance of a printed circuit board.

FIG. 4 is an explanatory diagram showing an image pickup screen of a printed circuit board.

FIG. 5 is a perspective view showing a modification of the first embodiment.

FIG. 6 is an explanatory diagram showing a state where the angle of view of the imaging lens is small.

FIG. 7 is a configuration diagram showing a second embodiment of the present invention.

FIG. 8 is a schematic diagram showing the configuration of a third embodiment of the present invention.

FIG. 9 is a block diagram showing a circuit configuration of each embodiment.

FIG. 10 is a flowchart showing an example of an inspection method in each example.

FIG. 11 is a configuration diagram showing a conventional example.

FIG. 12 is a configuration diagram showing another conventional example.

[Explanation of symbols]

 1 Printed Circuit Board (Inspection Object) 2 CCD Line Sensor (Imaging Element) 3 Imaging Lens 5 First Illumination Device (Illumination Means) 6 Second Illumination Device (Illumination Means) 12 LED (Light Emitting Light Source) 13 Condensing Lens ( Light guiding means) 14 Slit array (light guiding means) 15 Slit array (light guiding means)

Claims (7)

[Claims] 1. A visual inspection apparatus comprising illumination means for scanning an object to be inspected by an image sensor to inspect its appearance, wherein the illumination means is such that the direction of illumination light for illuminating the object to be inspected is inspected. An appearance inspection apparatus, which illuminates light reflected by an object so as to be in the same direction as the reflected light toward the image pickup device. 2. An appearance inspection apparatus comprising illumination means for scanning an object to be inspected with an image sensor to inspect its appearance, wherein the illumination means comprises first illumination means and second illumination means, The first illuminating means illuminates the object to be inspected so that the direction of the illuminating light is the same as the reflected light reflected by the object to be inspected and directed toward the image pickup device, and the second illuminating means is:
An appearance inspection apparatus, which illuminates an object to be inspected such that the direction of the illumination light illuminating the object to be inspected is different from the direction of the reflected light that is reflected by the object to be inspected and directed toward the image pickup device. 3. A visual inspection apparatus comprising illumination means for scanning an object to be inspected with an image sensor and inspecting its appearance, wherein the illumination means is an object to be inspected in a direction of illumination light for illuminating the object to be inspected. An appearance inspection apparatus, which illuminates light reflected by an object so as to be in a direction symmetrical to a reflected light toward the image pickup device. 4. An appearance inspection apparatus comprising illumination means for scanning an object to be inspected by an image sensor to inspect its appearance, wherein the illumination means comprises first illumination means and second illumination means, The first illuminating means illuminates the object to be inspected so that the direction of the illuminating light illuminating the object to be inspected is symmetrical to the reflected light that is reflected by the object to be inspected and is directed toward the image pickup device. An appearance inspection apparatus, which illuminates an object to be inspected such that the direction of the illumination light illuminating the object to be inspected is different from the direction of the reflected light that is reflected by the object to be inspected and directed toward the image pickup device. 5. The appearance inspection apparatus according to claim 1, wherein the illuminating means comprises a light emitting source and a light guiding means for aligning a light beam from the light emitting source in a predetermined direction. 6. The appearance inspection apparatus according to claim 1, wherein the image pickup device is a one-dimensional image sensor. 7. The visual inspection apparatus according to claim 1, wherein the image sensor is a two-dimensional image sensor.