JP2006251577A - Camera module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of defect caused by a minute foreign matter intruding inside a camera module. <P>SOLUTION: The camera module is provided in which an imaging device is attached to one surface of a base plate and covered with an optical unit having an optical system, and the lens unit of the optical system is moved by the driving part of the optical unit, the camera module is provided with a barrier to partially shield the inside space of the optical unit between the light transmission surface of the optical system and the foreign matter intrusion part of a casing. By such constitution, an effect to make a probability that the minute foreign matter intruding inside the housing moves low, and a probability that the minute foreign matter adheres to the light transmission surface of the optical system to cause staining defect low is obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a camera module, and more particularly to a technique that is effective when applied to countermeasures against foreign matter adhering to the inside of a camera module.

  In recent years, the use of information devices has further advanced, and information devices such as mobile communication terminals, so-called mobile phones or PDAs (Personal Digital Assistants), are widely used. In such information equipment, processing of image data with a large amount of information has become easier due to performance improvements such as an increase in the capacity of a storage device, a processing device, or an increase in communication speed. For this reason, mounting of a camera function for taking a still image is progressing in information equipment.

  In order to mount such a camera function, a CCD (Charge Coupled Device) type solid-state image sensor or a CMOS (Complementary Metal Oxide Semiconductor) type solid-state image sensor is mounted on a single substrate, and an optical unit incorporating an optical system is attached. A camera module using a signal processing circuit is used.

  In such a camera module, a function for photographing a higher definition image is required according to a customer's request for a higher quality image. However, it is not allowed to increase the size of the camera module. There is a need to reduce

  Therefore, for the purpose of increasing the total number of pixels of the image sensor and reducing the optical size, it is necessary to make the optical elements constituting the pixels of the image sensor fine and narrow the pixel pitch. In addition, when the optical size of the image sensor is reduced, the focal length of the optical system required to obtain the same angle of view is shortened, so the optical system can be further reduced to reduce the height of the camera module. it can.

  For this reason, the following Patent Document 1 describes a technique for thinning a camera module using a substrate having a filter function.

JP 2001-203913 A

  In the camera module, when a minute foreign object enters inside and adheres to the light transmission surface of the optical system, the light reaching the pixels of the image sensor interferes with the foreign object, and a defect called a stain occurs in the obtained image. Sometimes. This problem is caused by downsizing of the pixel pitch and the miniaturization of the elements constituting the pixel. Even if the foreign matter is fine, which has not been a problem in the past, it causes a defect, and the problematic foreign matter is fine. As it becomes, it becomes difficult to prevent the intrusion or movement of foreign matter.

An object of the present invention is to provide a technique capable of solving these problems and preventing the occurrence of defects due to foreign matters.
The above and other problems and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.
An image sensor is attached to one surface of the substrate, the image sensor is covered with an optical unit having an optical system, and the lens unit of the optical system is moved by a drive unit of the optical unit. A barrier that partially blocks the internal space of the optical unit is provided between the transmission surface and the foreign substance intrusion portion of the housing.

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
(1) According to the present invention, the barrier that partially shields the internal space of the housing of the optical unit has the effect of reducing the probability of movement of fine foreign matter that has entered the housing.
(2) According to the present invention, the effect (1) has an effect of reducing the probability of occurrence of a stain defect due to the attachment of fine foreign matter to the light transmission surface of the optical system.
(3) According to the present invention, the above effect (1) reduces the probability of moving a fine foreign object without performing complete sealing, so that an increase in cost can be suppressed.
(4) According to the present invention, due to the effect (1), since the barrier can be formed integrally with the housing, an increase in cost can be suppressed.

Embodiments of the present invention will be described below.
Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.
(Embodiment 1)
FIG. 1 is a plan view showing a camera module according to an embodiment of the present invention.
2, 3 and 4 are longitudinal sectional views taken along lines AB, DE and AC in FIG. 1, respectively. In FIG. 1, the upper part of the housing is shown through for the sake of explanation.

  The camera module of the present embodiment has a CCD-type or CMOS-type image pickup device 2 on one surface of a substrate 1 on which a wiring made of a thin film such as copper is formed on an insulator such as glass epoxy, and a subject on the image pickup device. An optical unit 3 for forming an image is attached. In FIG. 2 and other vertical sectional views, the optical unit 3 is a portion surrounded by a broken line.

  The imaging device 2 has a large number of optical elements that generate charges by injecting light in a plane, and outputs the light received by each pixel by photoelectric conversion as an image signal that is converted into an electrical signal that is color-separated. The obtained image signal is sent to the wiring of the substrate 1 by a bonding wire 4 or the like from a pad provided at the peripheral edge of the image sensor 2.

  The image sensor 2 is sealed by a base mount 5 bonded to the substrate 1 and a filter 6 fixed to the base mount 5, thereby preventing foreign matter from adhering to the image sensor 2. The base mount 5 and the filter 6 are covered with the optical unit 3.

  The filter 6 removes infrared rays by surface treatment or the optical characteristics of the material in order to prevent color change or smear from being caused by light outside the visible region.

  When the resolution is improved by increasing the definition of the image, it is necessary to focus on the subject with high accuracy. On the other hand, since manual focusing is complicated, an autofocus function is required. With the autofocus function, the distance to the subject is measured (photometric) on the device side, and the focus is adjusted automatically.

  For this reason, the optical unit 3 supports a plurality of lenses 7a for imaging light from the subject on the image pickup device 2 by the lens barrel 7b and moves the lens unit 7 in the optical axis direction. A drive unit 10 that finely adjusts in the axial direction and focuses on the image sensor 2 is housed in the housing 8.

  The lens unit 7 is provided with an arm 9 and a drive plate 10b extending perpendicular to the optical axis direction. The drive unit 29 connected to the drive plate 29 moves the drive plate 29 in the optical axis direction. Focus the optical system. The drive unit 10 rotates the drive shaft 10a according to the drive signal input to the terminal 11, and the rotational movement of the drive shaft 10a is performed in the optical axis direction of the drive plate 10b by the action of the spiral formed on the drive shaft 10a and the drive plate 10b. It is converted to vertical movement.

  At that time, in order to prevent an error in the position of the arm 9 due to the spiral gap, the drive plate 10b is pressed against the drive shaft 10a by the spiral spring 12a. In addition, in order to limit the movement of the arm 9 in the optical axis direction, a pole 13 is provided, and the arm 9 is pressed in the reverse direction by the spring 12b attached to the pole 13 to cause an error in the position of the arm 9. It is preventing.

  The spacers 23 and 24 are provided to mount a metal part such as a drive unit on a relatively soft part such as polycarbonate while ensuring a certain positional accuracy.

  On the other surface of the substrate 1, an image processing circuit that converts the image signal from the image sensor 2 into image data by performing processing such as digital conversion or compression, a storage circuit for storing the processed image data, and a drive unit are provided. A plurality of semiconductor devices 14 constituting a control circuit such as a regulator to be controlled are mounted, and the semiconductor devices 14 are covered with a sealing body 15 formed by potting or molding using epoxy resin or the like.

  The image data is displayed or stored on a flexible substrate 17 that is conducted from an electrode 16 provided at one end of the substrate 1 through an anisotropic conductive film (ACF). Sent to information equipment. Similarly, a flexible substrate 19 electrically connected to the electrode 18 provided at the other end of the substrate 1 through an anisotropic conductive film is connected to the terminal 11 of the optical unit 3 using solder 20, and the control circuit The drive unit 10 is controlled.

  The casing 8 of the optical unit 3 is made of a resin such as polycarbonate (PC) having high mechanical strength, and the terminal 11 is made of a metal such as copper. A gap of about 100 μm is provided between the housing 8 made of resin and the terminal 11 made of metal in consideration of a difference in thermal expansion coefficient or a problem of processing accuracy. It becomes an intrusion part. For example, when soldering the flexible substrate 19, the flux mixed in the solder 20 enters the optical unit 3 from the gap and becomes a foreign substance 21. When the foreign matter 21 that has entered moves inside the optical unit 3 and adheres to the light transmission surface of the optical system, for example, the surface of the filter 6, the imaging element 2 may be affected.

  Although the influence of the foreign material 21 on the image sensor 2 varies depending on the size of the foreign material, the optical size of the image sensor 2, the focal length (F value) of the lens, the distance from the image sensor 2 to the foreign material 21, that is, the image from the filter 6. It depends on the distance to the element 2.

  For example, in the camera module with 1.2 million pixels studied by the present inventors, a 1 / 2.9 inch image sensor and a lens with an F value of 3.8 are used, and the distance from the filter to the image sensor is about 1 mm. Note that the size of one pixel of the image sensor was 3.8 μm.

  According to the present inventors, when a foreign substance 21 having a size of 30 μm or more adheres to the filter 6 of this camera module, in the worst case, an unclear black spot appears in the monitor image, so-called a defect (hereinafter referred to as a stain defect). Was abbreviated to occur. Inside the optical unit 3, a gap of about 70 μm is generated between the inner wall of the optical unit 3 and the component parts, so that foreign matter of about 30 μm can move inside the optical unit 3.

  For these fine foreign objects, the physical force that controls the movement is different from the normal case. That is, the physical force that governs the movement of the foreign matter is more influenced by the electrostatic force, the adhesive force, and the frictional force than the gravity force and the inertial force. Therefore, in the movement of minute foreign matter, since the effect of gravity is small and the frictional force is large, the impact force or electrostatic force (coulomb) received in a very short time is required rather than rotating or sliding along the surface of the housing. (Force) increases the possibility of moving in the air in a straight line.

  Therefore, in the present embodiment, a barrier 22 that partially blocks the internal space of the housing 8 of the optical unit 3 is provided between the filter 6 that is a transmission surface of the optical system and the terminal 11 that is a foreign substance intrusion portion. is there. The barrier 22 is formed integrally with the housing 8, and the height is lower by a certain value (d1) than the lowest point (FIG. 3 hbtm) of the arm 9 of the optical system over the width of the internal space of the housing 8. ing. Here, the distance between the uppermost point (FIG. 3 htop) and the lowermost point (hbtm) is the operation amplitude of the arm 9.

  This value (d1) is preferably 50 μm or less in the intrusion direction of the foreign matter according to the result of the study by the present inventors. Similarly, the distance (d2) between the housing 8 and the barrier 22 of the optical unit 3 and the distance (d3) between the lens unit 7 and the barrier 22 are preferably 50 μm or less.

  This barrier 22 regulates the linear movement of the minute foreign material 21 that has entered from the terminal 11 portion as shown by the arrow in FIG. 4, and reduces the probability that the foreign material 21 reaches the filter 6 and causes a stain defect. Can do.

  On the other hand, in the conventional camera module without the barrier 22 shown in FIG. 5, the foreign matter 21 that has entered the inside of the housing 8 is compared as shown by an arrow (1) in FIG. 5 (hereinafter circled in the figure). There is a possibility of moving to the filter 6 easily.

  Further, as shown in FIG. 5, the foreign matter may enter through the paths indicated by arrows (2) and (3). The arrow (2) enters from the gap between the lens unit 7 and the housing 8, passes through the inside of the actuator and reaches the filter 6, and the arrow (3) is the lens unit 7 and the housing 8 similarly to the arrow (2). This is a path that directly enters the filter 6 through the gap.

  As measures against the foreign matter 21 entering from the gap between the lens unit 7 and the housing 8, as shown in FIG. 6 and FIG. 7 which is a longitudinal sectional view along the FG line, the lens unit 7 and It is effective to add an annular barrier 22 to the base mount 5 respectively. Here, the distance d1 between the barriers 22 is preferably 50 μm or less, and the height l1 of the barriers 22 is preferably 1,000 μm or more.

  FIG. 8 and FIG. 9, which is a longitudinal sectional view taken along the line HJ, shows a case where such a barrier 22 is added to the example shown in FIGS. 1 and 2 described above. As a result, it is possible to take measures against all foreign matters entering from the directions of the arrows (1), (2), and (3).

  Here, since the influence of gravity is reduced by the above-described dimensional effect, the foreign material 21 attached to the inner wall of the housing 8 due to static electricity remains attached regardless of the orientation of the housing 8 and moves regardless of the direction of gravity. Therefore, it is effective to form the barrier 22 on both sides.

  In addition, when the movement path | route of the foreign material 21 which penetrate | invaded can be estimated from the structure inside the housing | casing 8, etc., the barrier 22 is arrange | positioned so that the movement path | route of the foreign material 21 may be interrupted | blocked, and the foreign material 21 of the foreign material 21 is more effective. It becomes possible to prevent movement.

  As described above, it is more effective to provide not only one barrier but also a plurality of barriers within a cost allowable range. In addition, as described above, the value at which the gap is effective is described. Even if this value cannot be satisfied for some reason, a combination of a plurality of barriers can provide a result close to that even if it is not perfect.

  As described above, this method does not completely limit the intrusion and movement of a foreign substance, but attempts to obtain the same effect as if movement is completely limited by the following two methods.

  1. The probability that a foreign substance moves due to a gap of about 50 μm is reduced, and the occurrence rate of stain defects is reduced.

  2. By making the path from the foreign substance entrance to the upper part of the filter as long as possible, the occurrence rate of stain defects due to foreign substances is reduced.

  On the other hand, as another method for eliminating the influence of foreign matter, there is a method of completely sealing without any gap. However, this method is not desirable because it requires an increase in the manufacturing process and processing accuracy of parts, which increases costs. In the present embodiment, the barrier 22 that partially shields the internal space prevents the movement of the foreign substance 21 between the infrared filter 6 of the optical system and the terminal 11 part, which is a foreign substance intrusion part. On the other hand, it is possible to prevent the fine foreign matter 21 from adhering to the optical system.

  Although the present invention has been specifically described based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. is there.

For example, FIG. 10 and FIG. 11, which is a longitudinal sectional view along the line KL, is a modification of the above-described embodiment. In this example, the arm 9 and Barriers 22 are provided above and below within a range that does not hinder the movement of the drive plate 29. In the camera module as in the present embodiment, the vertical relationship is not fixed in a constant state during carrying or use, so it is effective to form a barrier 22 on both sides. Here, it is desirable that d5 and d6 are 50 μm or less and l2 is 1,000 μm or more.
(Embodiment 2)
From here on, for the sake of simplicity, an example in which the present invention is applied to a single-focus camera module will be described. In this example, the autofocus function is omitted by increasing the depth of field of the lens unit 7.

  For example, in the example shown in FIG. 12 and FIG. 13 which is a longitudinal sectional view taken along line MN in FIG. 12, the barrier 22 is within the range of x1 to x2 within a range that does not hinder the movement of the lens unit 7 on the base mount 5. Is provided. Here, x1 is a point where the vertical direction of the outer frame of the lens unit 7 and the base mount 5 intersect, and x2 is the other end of the base mount 5. As shown in FIG. 13, the position of the barrier 22 may be anywhere on the base mount 5 from x1 to x2. Here, the gap d7 between the lens unit 7 and the barrier 22 on the base mount 5 is desirably 50 μm or less.

  Similarly, FIGS. 14 to 16 show modifications of this embodiment. Here, the gaps d8, d9, d10 between the lens unit 7 and the barrier 22 on the base mount 5 are desirably 50 μm or less, and the lengths l3, l4, l5 are desirably 1,000 μm or more.

  A description will be added to FIG. The barrier of FIG. 16 is characterized in that the end of the barrier is smoothly connected to the end of the lens unit (= no protrusion). However, also here, the gap d10 between the lens unit 7 and the barrier 22 on the base mount 5 is preferably 50 μm or less. The invading foreign substance 21 moves while colliding with the lens unit 7 and the wall of the barrier 22. Since the end of the barrier 22 is smoothly connected to the end of the lens unit 7, the probability that the foreign material 21 stays near the gap is reduced. Therefore, the probability that the foreign material 21 enters from the gap is reduced.

It is a top view which shows the camera module which is one embodiment of this invention. It is a longitudinal cross-sectional view along the AB line in FIG. FIG. 2 is a longitudinal sectional view taken along the line DE in FIG. 1. It is a longitudinal cross-sectional view along the AC line in FIG. It is a longitudinal cross-sectional view which shows the conventional camera module. It is a top view which shows the modification of the camera module which is one embodiment of this invention. It is a longitudinal cross-sectional view along the FG line in FIG. It is a top view which shows the modification of the camera module which is one embodiment of this invention. It is a longitudinal cross-sectional view along the HJ line in FIG. It is a top view which shows the modification of the camera module which is one embodiment of this invention. It is a longitudinal cross-sectional view along the KL line in FIG. It is a top view which shows the modification of the camera module which is other embodiment of this invention. It is a longitudinal cross-sectional view along the MN line | wire in FIG. It is a longitudinal cross-sectional view which shows the modification of the camera module which is other embodiment of this invention. It is a longitudinal cross-sectional view which shows the modification of the camera module which is other embodiment of this invention. It is a longitudinal cross-sectional view which shows the modification of the camera module which is other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Image pick-up element, 3 ... Optical unit, 4 ... Bonding wire, 5 ... Base mount, 6 ... Filter, 7 ... Lens unit, 7a ... Lens, 7b ... Lens tube, 8 ... Housing, 9 ... Arm DESCRIPTION OF SYMBOLS 10 ... Drive part, 10a ... Drive shaft, 10b ... Drive plate, 11 ... Terminal, 12a, 12b ... Spring, 13 ... Pole, 14 ... Semiconductor device, 15 ... Sealing body, 16, 18 ... Electrode, 17, 19 ... flexible substrate, 20 ... solder, 21 ... foreign matter, 22 ... barrier, 23 ... spacer, 24 ... spacer

Claims (5)

An image sensor is attached to one surface of the substrate, the image sensor is covered with an optical unit having an optical system, and the lens unit of the optical system is moved by a drive unit of the optical unit. A camera module, wherein a barrier that partially blocks an internal space of an optical unit is provided between a transmission surface and a foreign substance intrusion portion of a housing. The camera module according to claim 1, wherein the barrier is formed integrally with a housing of the optical unit. The drive unit moves the lens unit to adjust the focus, the intrusion unit is a gap between a control signal terminal connected to the drive unit and the housing, and the light transmission surface is the surface of the filter. The camera module according to claim 1, wherein the camera module is characterized in that: The camera module according to any one of claims 1 to 3, wherein the barrier is provided above and below an internal space of a housing of the optical unit. The camera module according to claim 1, wherein a plurality of the barriers are provided on the same surface.

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