JPS6017963Y2 - Mounting structure of image sensor in imaging device - Google Patents

Description

[Detailed description of the invention] This invention relates to a mounting structure for an image sensor in an imaging device using a semiconductor image sensor (image sensor) such as a CCD, and in particular, it is extremely easy to align the optical axis of a lens system with respect to the image sensor. It was made possible to do so.

In recent years, imaging devices using semiconductor image sensors such as CCDs (charge-coupled devices) have been widely used as image sensors in the field of various industrial measurements such as defect detection. The image sensor that receives the image obtained by the lens system is arranged so as to face the back surface of the lens system, and the incident optical axis of the lens system and the center of the light receiving surface of the image sensor are very far apart. It is necessary to match with high precision.

As an example, the mounting structure of an image sensor in a conventional defect inspection device will be explained based on FIG. The printed circuit board 3 is mounted and positioned on a printed circuit board 3, and this printed circuit board 3 is further mounted on a lens holder 4.
Screws 5, 5 are attached to the protrusions 4a, 4b protruding from the back side of the
is firmly fixed by.

When aligning the optical axis as described above, with the printed circuit board 3 temporarily secured to the lens holder 4 by slightly loosening the screw 5.5, test the object to be detected with the reference center line drawn. In addition to imaging and scanning,
A spindle portion of a micrometer for position adjustment is brought into contact with two adjacent sides of the printed circuit board on which the run sensor is mounted.

Then, the deviation between the optical axis of the lens system and the center of the line sensor is electrically detected from the video signal for the above test purpose, and based on the result, the X-axis and Fine feed is applied to each in the Y-axis direction for positioning.

However, such optical axis alignment work is extremely complicated and takes a lot of time, and the positioning accuracy of the line sensor depends on the means for fixing the printed circuit board to the lens holder. Even if this is done, the positional shift may occur again when the screws are tightened again, so there is a need to make structural improvements to simplify the optical axis alignment as described above.

This idea was made against the background mentioned above.
A positioning plate is interposed between the printed circuit board that fixedly supports the image sensor and the lens holder, and the positioning plate has terminal holding holes that control the positioning of the image sensor in accordance with the terminal arrangement of the image sensor. A positioning hole that tightly fits into the reference pin protruding from the lens holder is provided, and the relative positioning relationship between the reference pin and the positioning hole and the relative positioning between the terminal of the image sensor and the terminal engagement hole are determined. It is an object of the present invention to provide a mounting structure for an image sensor that allows optical axis alignment to be performed mechanically and extremely easily without the complicated optical axis alignment work as in the past. .

Hereinafter, one embodiment of this invention will be described in detail with reference to the drawings for the case of the defect inspection apparatus described above.

FIG. 2 shows an example of the mounting structure of the image sensor according to this invention, and the case and the protective cover covering the internal equipment are not shown.

In the figure, reference numeral 10 denotes a lens holder with an irregular cross-sectional shape that is attached to the front side of a case that constitutes the main body of the device, and a lens barrel 12 containing a desired lens 11 is disposed on the outside of this lens holder 10. At the same time, four protrusions 13, 13, . There are four reference pins 14, 1 that control the positioning of the line sensor, which will be described later.
4... are integrally protruded with reference to the incident optical axis of the lens system.

The printed circuit board 15 on which a desired circuit element is mounted is mounted on the tip side of the protrusion 13.13... with the screw 15a.
, 15a... are arranged to be firmly fixed, and a socket 16 is integrally fixed to the inside of this printed circuit board 15 by soldering, and a screw mounting formed on the printed circuit board 15 is fixed thereto. The necessary mounting holes have clearances for the screws 15a, 15a..., and as a result, if the screws 15a, 15a... are loosened, the printed circuit board 15 will be attached to the projection 13 ,13...
・The position can be adjusted against.

On the other hand, a thin disk-shaped positioning plate 18 for positioning a DIP type one-dimensional CCD image sensor 1, that is, a line sensor 17 is disposed on the inner end surface of the small diameter cylindrical portion 10b. As shown in FIG. 3, the reference pins 14, 14...
Four positioning holes 19,1 that fit tightly against...
9... are bored with reference to the center line 13 that coincides with the optical axis, and the positioning plate 18 including the line sensor 17 is positioned and held with respect to the lens holder 10 by the fitting relationship between the two. ing.

That is, as shown in FIG.
The lead frame 17 of the line sensor 17 is located in the center of the
a, 17a...... and a large number of engagement holes 2θ, 20... that fit closely in accordance with the arrangement and pitch thereof.
The center line 1. coincides with 13. The lead frames 17 of the line sensor 17 are arranged in parallel with each other as a reference.
ay 17a... The leading ends of the lead frames 17a, 17a..., which have been inserted through the engagement holes 20, 20..., are inserted into the socket 16 on the printed circuit board 15. As a result, the line sensor 17 is positioned by the positioning plate 18, and at the same time the socket 16 and the printed circuit board 15
The incident optical axis of the lens system and the center of the light-receiving surface of the line sensor 17 are perpendicular to each other on the light-receiving surface, and the image obtained by the lens system is transferred to the light-receiving surface of the line sensor 17. It is designed to receive light in the band.

Next, the assembly procedure of the above structure will be described. First, each lead frame 17a, 17a of the line sensor 17 is assembled.
. . . in the engagement hole 20.2 of the positioning plate 18.
Lead frames 17a, 17a, . Attach the tip of the printed circuit board 1
5 into the socket 16, and the line sensor 17,
The positioning plate 18, the socket 16, and the printed circuit board 15 are interconnected and integrated.

Next, the positioning plate 18 is positioned relative to the reference pins 14, 14, .
When the line sensor 17 is inserted through the positioning hole 19° 19..., the line sensor 17 is positioned so that the center of the light receiving surface of the line sensor 17 coincides with the incident optical axis of the lens system, and then the screw 15a, 15a... to fix the printed circuit board 15 to the lens holder 10, the intended purpose is achieved.

Therefore, in the manufacturing process of the line sensor itself, the arrangement and pitch of the lead frames 17a, 17a, etc. are sufficiently reliable in terms of dimensional accuracy, and as shown in FIG. 11 and the arrangement center 1° of the elements that make up the actual light-receiving band are set to match, the positional accuracy between the incident optical axis of the lens system and the center of the light-receiving surface of the line sensor is Positioning holes 19, 19 in positioning plate 18
......, the dimensional accuracy of the engaging holes 20, 20..., the dimensional accuracy of the reference pins 14, 14..., and the assembly error between each part during assembly. determined by

Therefore, according to the above configuration, even if there is some assembly error, the relative positional accuracy of the reference pins 14, 14 and the positioning holes 19, 19, and the line sensor Lead frames 17a, 17a...
Due to the relative positional accuracy of the engagement holes 20, 20, . . . and the engagement holes 20, 20, .

Also, suppose that the element array center 12 of the line sensor 17 and the lead frames 17a, 17a...
If the array center 1□ of ... does not match and there is a slight dimensional error, take the following countermeasures.

That is, in addition to the above-mentioned regular positioning plate, the arrangement center 1. of the engagement holes 20, 20, . Several positioning plates are prepared whose positioning plates are shifted stepwise in the X direction (a slight shift in the Y direction corresponds to the traveling direction of the object to be detected, that is, the sub-scanning direction, so there is no functional problem).

As shown in FIG. 5, this stepwise deviation of the center line 14 in the X direction is an integral multiple of the optical axis deviation allowable width a allowed even with a regular positioning plate, that is, a, 2 as shown in the same figure.
a, set to dimensions 3a.

Then, the degree of optical axis deviation is electrically detected by the method described above using a regular positioning plate.

At this time, when the alignment center of the line sensor 1 degree with respect to the optical axis center of the lens system is within the area A based on the allowable width a, there is no need to make any adjustment as the regular positioning plate is used.

Further, if it is assumed that the element arrangement center 1□ of the line sensor is at position b in area B other than area A with respect to the optical axis center, then the engagement hole arrangement center 1 □ is with respect to the center 13 of the positioning plate. If a positioning grating is used that has a dimension a on the left side in the X direction, the optical axis deviation will fall within the allowable range A.

In addition, in this example, the above-mentioned allowable dimension width a is 0.3 m/m,
Lead frame arrangement center 1□ and element arrangement center 1
The dimensional error from ゜ is 0.6 to 0.7 m/m on one side.
(Max), and the positioning plates prepared can be used by flipping them over when shifting to the left or right, so there is one regular plate and one with a shift of 0.3 m/m.
One sheet shifted by 0.6 m/m is sufficient for a total of three sheets.

In the above example, lead frames 17a, 17a of the line sensor are placed in the center of the positioning plate 18 as a part that controls the positioning of the line sensor.
The case where the engaging holes 20, 20, . . . corresponding to the arrangement of . Engagement holes 20, 20... are drilled only in the four corners of the
For other parts, the same effect as in the above example can be obtained even if the opening 20a is provided so that the outer parts of the lead frames 17a and 17a are closely inscribed without providing individual engagement holes. .

As is clear from the above explanation, in the mounting structure of the image sensor according to this invention, a plurality of projecting structures are provided on the back surface of a lens holder equipped with a desired lens system, with reference to the incident optical axis of the lens system. a reference pin, and a positioning hole that is positioned on the back surface of the lens holder by the reference pin, and that is provided in correspondence with a positioning hole that tightly fits into the reference pin and a terminal arrangement of the image sensor. A positioning plate in which a terminal retaining hole is formed with the optical axis as a reference, which holds the center of the light-receiving surface at the optical axis position by receiving and engaging each terminal, and a positioning plate further downstream than the positioning plate. and a printed circuit board that is fixed to the back surface of the lens holder with screws so as to be located at the center of the lens holder, and on which a socket into which each terminal of the image sensor is inserted through the terminal engagement hole is arranged together with a circuit element. This makes it possible to align the optical axis extremely easily by simple mechanical positioning, without requiring the complicated electrical positional deviation detection means used in the past. Furthermore, since it is hermetically housed within the area surrounded by the three positioning plates, it has excellent dustproof properties.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an example of a conventional image sensor mounting structure, Fig. 2 is a main part explanatory diagram showing an example of an image sensor mounting structure in this invention, and Fig. 3 is a plan view showing details of the positioning plate. 4 is a perspective view of the line sensor, FIG. 5 is an explanatory diagram for explaining optical axis deviation in this structure, and FIG. 6 is a plan view showing an aspect of a positioning plate as another embodiment. . 10... Lens holder, 11... Lens, 14... Reference pin, 15... Printed circuit board, 17... Line sensor (imaging element), 17a...Lead frame (terminal), 1
8...Positioning plate, 19...Positioning hole, 20...Engagement hole (terminal engagement portion).

Claims (1)

[Claims for Utility Model Registration] A mounting structure for an image pickup device in an image pickup device in which an image pickup device for receiving an image obtained by the lens system is disposed on the back side of a lens holder having a desired lens system, the lens A plurality of reference pins protruding from the back surface of the holder with reference to the optical axis of the lens system, and a plurality of reference pins that are positioned on the back surface of the lens holder by the reference pins, and the lens holder is positioned closely with respect to the reference pins. Positioning holes to be fitted and terminal engaging holes provided corresponding to the terminal arrangement of the image pickup device and holding the center of the light receiving surface at the optical axis position by receiving and engaging each terminal are respectively aligned with the optical axis. a positioning plate that is bored with reference to the positioning plate, and a positioning plate that is screwed and fixed to the back surface of the lens holder so as to be located further back than the positioning plate, and that is inserted through the terminal engagement hole of the image sensor. 1. A mounting structure for an imaging device in an imaging device, characterized in that a socket into which each terminal is inserted is made up of a printed circuit board disposed together with a circuit element.