JPS63128207A - Inspecting device for packaging parts - Google Patents

Abstract

PURPOSE:To derive exact height information by detecting the position of the center of gravity of a brightness distribution running along the direction being orthogonal to its linear direction, from a two-dimensional image by an optical sensor. CONSTITUTION:The product of brightness information A and position information B at every position of a brightness distribution of a two-dimensional image is calculated by a multiplier 81. Subsequently, the sum total of the product obtained at every position is calculated by an accumulator 82, and simultaneously, the sum total of the brightness information A at every position is calculated by the other accumulator 82. Next, the dividing a result obtained by the accumulator 82, by a result obtained by the accumulator 83, in a divider 84, a position of the center of gravity of the brightness distribution is detected. The bright distribution is symmetrical centering around a true peal position, therefore, the position of the center of gravity detected by a center-of-gravity detecting circuit 8 coincides with the peak position. Even if the noise is generated in the vicinity of the peak, its noise quantity is nearly equal to zero, comparing with the quantity of the brightness information contained in the whole brightness distribution. Accordingly, the position of the center of gravity coincides roughly with the true peak position without being influenced by a noise, therefore, exact height information is obtained.

Description

[Detailed Description of the Invention] [Summary] The present invention is a mounted component inspection device that inspects the mounting state of components on a printed circuit board using a photosection method. By determining the center of gravity of the brightness distribution and calculating the height information of the part from this center of gravity, detection errors due to noise are eliminated.
This allows accurate height information to be obtained.

[Industrial application field]

The present invention is a mounted component inspection device that automatically inspects the mounting status (e.g., different types, mounting positions, excess/deficiency, etc.) of electronic components (particularly chip components) mounted on a printed circuit board using an optical cutting method. Regarding.

In recent years, as seen in chip components in particular, the miniaturization of components and the increase in the density of packaging have progressed, making visual inspection by human eyes, which has traditionally been a common practice, difficult. the current,
Against this background, there is a strong desire to automate the visual inspection of mounted components.

[Conventional technology]

FIG. 7 (111) shows a schematic configuration of a conventional mounted component inspection device using the optical cutting method.In the conventional device, first the light source 1
A linear light beam I11 is created by passing the light output from the linear slit 2, and this light beam 1
1 is irradiated onto the printed board P through the lens 3 obliquely from above. Then, a light cutting line along the shape of the component M is formed there, and this is imaged onto the two-dimensional sensor 5 by the lens 4 from diagonally above, which is different from the irradiation direction. As shown in FIG. 7 (bl), the two-dimensional sensor 5 obtains a two-dimensional image having a brightness distribution corresponding to the light cutting line. 6 converts it into a digital signal and sends it to the peak detection circuit 7. This peak detection circuit 7 converts the two-dimensional image shown in FIG. This is a circuit that detects the peak of the brightness distribution along the direction (X direction) orthogonal to this for each position in the line direction (X direction) in Finally, based on this height information, the mounting state of the component M is inspected by an inspection means (not shown).

[Problem that the invention seeks to solve]

In the above-mentioned conventional device, the peak detection circuit 7
Since height information was obtained from the peak position of the brightness distribution obtained in , the detected peak position could sometimes deviate from the true peak position due to the influence of small noise near the peak. For example, in Figure 7 (line a of bl
The brightness distribution along b is shown in Figure 8. As shown in the figure, when spike-like noise overlaps near the peak and exceeds the peak value, the position of the noise is the peak position. This resulted in a large detection error.

When an error occurs in the peak position in this way, a larger error also occurs in the height information of the component obtained based on the peak position, which leads to a decrease in the accuracy of component inspection.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a mounted component inspection apparatus that can obtain accurate height information without being affected by the noise described above.

[Means for solving problems]

The mounted component inspection device of the present invention detects the center of gravity of the brightness distribution along a direction orthogonal to the line direction from a two-dimensional image detected by an optical sensor, and obtains height information from this center of gravity. This is what I did.

[For production]

Generally, the above brightness distribution is approximately symmetrical about the true peak position. Therefore, the center of gravity position obtained from such a brightness distribution almost coincides with the true peak position. Even if noise occurs near the peak, the amount of noise is almost equal to zero compared to the amount of brightness information included in the entire brightness distribution. From this, the center of gravity position is hardly affected by noise and almost represents the true peak position.

Therefore, height information obtained based on such a center of gravity position is extremely accurate.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

In the same figure, the components from the light source 1 to the A/D converter 6 are the same as the conventional device shown in FIG. 7 fa, so their explanation will be omitted. A feature of this embodiment is that a gravity center detection circuit 8 is provided at the next stage of the A/D converter 6. This center of gravity detection circuit 8 will be described in detail later, but from a two-dimensional image similar to that shown in FIG. (y
direction) for each position, the direction perpendicular to this (X direction)
This is a circuit that finds the center of gravity of the brightness distribution obtained along the . In this embodiment, height information is calculated from the center of gravity position obtained by the center of gravity detection circuit 8, and based on this height information,
The mounting state of the component M (for example,
Inspections are made for differences in product types, installation locations, excess and deficiencies, etc.).

In this inspection, for example, the three-dimensional shape of the component M is known by obtaining the height information about the entire printed board P,
This is done by comparing this shape with a reference shape and determining the mounting state.

FIG. 2 shows an example of a specific circuit configuration of the center of gravity detection circuit 8. As shown in FIG. This circuit 8 is composed of one multiplier 81, two accumulators 82, 83, and a divider 84.

In the above configuration, the multiplier 81 is configured to operate at each position of the above-mentioned brightness distribution (an example thereof is shown in FIG. 3) of the two-dimensional image obtained from the two-dimensional sensor 5 via the A/D converter 6. The product A*B of brightness information A and position information B is calculated. The accumulator 82 calculates the sum ΣA* of the products A*B obtained for each position.
Calculate B.

At the same time, the other accumulator 83 calculates the sum ΣA of the brightness information A for each position. Finally, the divider 84 divides the result (ΣA)kB) obtained by the accumulator 82 by the result (ΣA) obtained by the accumulator 83. This result then becomes the center of gravity of the brightness distribution.

As shown in FIG. 3, the brightness distribution is approximately symmetrical about the true peak position. Therefore, the center of gravity position obtained by the center of gravity detection circuit 8 almost coincides with the true peak position. Even if spike-like noise occurs near the peak as shown in the figure, the amount of noise is almost equal to zero compared to the amount of brightness information included in the entire brightness distribution. From this, the center of gravity position is hardly affected by noise and almost coincides with the true peak position, so accurate height information can be obtained.

Next, FIG. 4 shows characteristic parts of another embodiment of the present invention.

In this embodiment, the center of gravity detection circuit 8 shown in FIG.
The brightness information A from the /D converter 6 is provided via a low-level brightness information exclusion circuit 9.

The circuit 9 is a circuit that prevents brightness information below a predetermined slice level SL from being provided to the center of gravity detection circuit 8. A specific example of its configuration includes a comparator 91 and a gate 92, as shown in FIG. The comparator 91 compares the brightness information A at each position of the brightness distribution described above with a predetermined slice level SL, and outputs an on signal when the former is greater than the latter. gate 92
is opened only when the on signal is output from the comparator 91, and the brightness information A at this time is passed and sent to the center of gravity detection circuit 8. By doing so, it is possible to avoid referring to the unstable brightness information of the slice level setting circuit in detecting the center of gravity position described above.

In the above embodiment, the fixed slice level SL was used, but the slice level S
L may be set to an optimal level. FIG. 5 shows the configuration of another embodiment in which such a slice level setting circuit 10 is provided.

The slice level setting circuit 10 includes a peak detector 10
1 and a multiplier 102.

The peak detector 101 detects the peak value of the brightness distribution, that is, the maximum value A HA X of all the brightness information A. The multiplier 102 multiplies the peak value AMAX by a fraction (C) (for example, 0.5 times), and uses this value as the slice level SL of the comparator 91 described above. Further, the brightness information A and the position information B that are sent until the peak detection is completed by the peak detector 101 are stored in the storage circuits 11 and 12 respectively, and after the peak detection is completed, the brightness information A and the position information B are stored. Information in circuits 11 and 12 is read out sequentially.

According to the embodiments shown in FIGS. 4 and 5 above, the error is lower than or equal to the slice level SL (fixed in the embodiment of FIG. 4, for example, 1/2 times the peak value AMAX in the embodiment of FIG. 5). The center of gravity position can be detected by excluding stable brightness information and using only stable brightness information near the peak. Therefore, as shown in Figure 6, even if the influence of stray light from, for example, a high reflectance area appears in a low level area of the brightness distribution, this will cause the center of gravity to be It will not shift to the side, and therefore more accurate height information can be obtained.

In the present invention, the configuration of the optical system is not limited to that shown in FIG. 1, and may be one in which a light cutting line is formed on a printed board to obtain a corresponding two-dimensional image. For example, any configuration may be used. For example, the two-dimensional image may be obtained by using a line sensor instead of the two-dimensional sensor 5 and sequentially detecting the light cutting line in a line shape along the height direction.

〔Effect of the invention〕

According to the mounted component inspection device of the present invention, accurate height information that is not affected by noise can be obtained based on the center of gravity position of the brightness distribution, and therefore, highly accurate mounted component inspection is possible. .

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one implementation of the present invention, FIG. 2 is a circuit diagram showing an example of a specific configuration of a center of gravity detection circuit 8 according to the same embodiment, and FIG. A diagram showing the brightness distribution and the position of its center of gravity, =13- Figure 4 is a circuit diagram showing characteristic parts in another embodiment of the present invention, Figure 5 shows characteristic parts in still another embodiment of the present invention A circuit diagram, FIG. 6 is a diagram showing the brightness distribution obtained by the embodiment of FIGS. 4 and 5 and its center of gravity, FIG. 7 (al is a schematic configuration diagram showing a conventional device, FIG. bl is a diagram showing an example of a two-dimensional image obtained by the two-dimensional sensor 5 of the conventional device, and FIG. 8 is a diagram showing the brightness distribution obtained by the conventional device and its detected peak position. ■... Light source, 2... Slit, 3.4... Lens, 5... Two-dimensional sensor, 8... Center of gravity detection circuit, 81... Multiplier, 82.83... Accumulation 84...Divider, 9...Low level brightness information exclusion circuit, 91...Comparator, 92...Gate, 10...Slice level Pa foot circuit, 101...
Peak detector, 102... Multiplier, 1112... Storage circuit.

Claims (1)

[Scope of Claims] 1) Light irradiation means (1, 2, 3) for irradiating a linear light beam onto a printed circuit board on which components are mounted; light detection means (4, 5) for detecting a light cutting line formed on the plate as a two-dimensional image with a light sensor (5) from a direction different from the direction of the irradiation; and a height obtained from the two-dimensional image. In a mounted component inspection apparatus having an inspection means for inspecting the mounting state of the component based on information, the centroid position of the brightness distribution along a direction orthogonal to the line direction from the two-dimensional image obtained by the light detection means. A mounted component inspection apparatus characterized in that the mounted component inspection apparatus is equipped with a center of gravity detection means (8) for detecting the center of gravity, and the height information is obtained from the center of gravity position. 2) The centroid detection means includes a multiplier (81) that calculates the product of brightness information and position information at each position of the brightness distribution.
), a first accumulator (82) that calculates the sum of the products obtained by the multiplier, and a second accumulator (83) that calculates the sum of brightness information at each position of the brightness distribution. Said first
a divider (84) that divides the result obtained by the second accumulator by the result obtained by the second accumulator, and the result obtained by the divider is set as the center of gravity position. A mounted component inspection device according to claim 1, characterized in that: 3) low-level brightness information exclusion means (9) for excluding brightness information below a predetermined slice level included in the brightness distribution from detection of the center of gravity position by the center of gravity detection means;
) The mounted component inspection apparatus according to claim 1 or 2, characterized in that the mounted component inspection apparatus is provided with: 4) The low-level brightness information exclusion means includes a comparator (91) that compares brightness information at each position of the brightness distribution with the predetermined slice level; 4. The mounted component inspection device according to claim 3, further comprising a gate (92) that closes when the device is in use, and opens at other times to send the brightness information to the center of gravity detecting means. 5) A slice level setting means (10) is provided for determining a peak value of the brightness distribution and setting a value obtained by multiplying the peak value by a decimal number as the slice level. Or the mounted component inspection device according to item 4. 6) The mounted component inspection apparatus according to claim 5, wherein the decimal number is 0.5. 7) The mounted component inspection apparatus according to any one of claims 1 to 6, wherein the optical sensor is a two-dimensional sensor.