WO2013175944A1 - Imaging device - Google Patents

Description

Imaging device

The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus that is small and suitable for mass production.

Small and thin imaging devices (hereinafter also referred to as camera modules) are used in mobile terminals such as mobile phones and PDAs (Personal Digital Assistants). As an image pickup element used in these image pickup apparatuses, a solid-state image pickup element such as a CCD type image sensor or a CMOS type image sensor is known. In recent years, the number of pixels of an image sensor has been increased, and higher resolution and higher performance have been achieved.

By the way, in the technical field of electronic circuit components in which IC (Integrated Circuits) chips and other electronic components are mounted on a circuit board, a metal paste (for example, a solder paste) is applied (potted) in advance to a predetermined position on the circuit board. Developed a technology to manufacture electronic circuit components at low cost by reflow processing (heating process) with the electronic components placed at the position and solder mounting the electronic components on the circuit substrate Has been. In recent years, it has been studied to use such a technique for an image pickup apparatus. However, in order to prevent dust or the like from entering the surface of an image pickup device from the outside, a camera module is usually used, for example, with an image pickup device and a mirror. A kind of sealed space is formed between the frame or the lens. At this time, if the camera module is heated during reflow, the internal pressure in the sealed space increases, which may cause deformation or destruction of the lens frame. Such a problem may occur even in the inspection process after the completion of the camera module or when the camera module is placed in a high temperature condition such as in a car after the market.

問題 More specifically explain the problem of internal pressure rise. As an example of a camera module, there is known a camera module in which a male screw is formed on a lens holder and a female screw is formed on a lens barrel so that the relative position between the lens holder and an image sensor can be adjusted. In such a camera module, in order to prevent dust from entering the surface of the image sensor from the outside, it is usually screwed together to complete a camera module, for example, as disclosed in FIG. In addition, it is designed so that a sealed space can be formed between the holder and the image sensor.

On the other hand, in order to improve the productivity of camera modules, a technique for performing reflow processing (heating processing) when soldering electronic components used in camera modules onto circuit boards has been developed. However, when the reflow process is applied to the camera module of Patent Document 1, the temperature of the sealed space rises due to heating, the internal pressure rises, and the holder may be deformed or damaged. Further, when intense light is irradiated in the inspection process of the camera, the internal pressure is increased due to heating, which may cause the same problem.

JP 2008-237756 A International Patent Publication No. 2012/008268 Pamphlet

In order to solve such a problem, the present inventor in Patent Document 2 provides an air escape portion at a position out of phase with a notch communicating with the outside, thereby ensuring the air permeability inside and outside. An imaging device that can prevent intrusion has been proposed. However, depending on the installation location of the imaging device, there is a case where dust is generated due to friction when the holder for holding the imaging lens is screwed into the lens frame. No countermeasure has been proposed.

The present invention has been made in view of the problems of the related art, and provides an imaging apparatus that can prevent dust and unnecessary light from entering while ensuring air permeability inside and outside, and can suppress the generation of dust. With the goal.

An imaging apparatus according to claim 1 is provided.
An imaging lens;
A holder comprising a head and a torso, and holding the imaging lens;
A lens frame to which the holder is attached;
An image pickup device hermetically attached to the lens frame,
The head of the holder is in a non-contact state with the lens frame, the holder is provided with a male screw around the body portion, the lens frame is provided with a female screw that is screwed into the male screw, A part of the outer periphery is cut to form an air escape portion that communicates the inside and the outside of the lens frame, and the air escape portion is formed when the male screw and the female screw are screwed together. It is characterized by being provided radially outward from the inner peripheral ridgeline.

According to the present invention, when the holder is screwed into the lens frame while adjusting the position of the imaging lens in the optical axis direction, the head of the holder is not in contact with the lens frame. The head of the holder and the lens frame do not slide, and generation of dust due to friction can be avoided. However, when the holder head is not in contact with the lens frame, a gap occurs between the holder head and the lens frame, and dust and unnecessary light enter from the outside through the gap. It becomes easy to do.

In particular, in the present invention, a part of the outer periphery of the male screw portion is cut to form an air escape portion that communicates the inside and the outside of the lens frame, so that the inside of the sealed imaging device becomes hot. Even in this case, there is an advantage that the expanded air can be discharged to the outside through the air escape portion, thereby suppressing, for example, deformation or breakage of the holder or the like. If a simple air escape portion is formed, dust and unnecessary light may easily enter the imaging device. Therefore, in the present invention, when the male screw and the female screw are screwed together, the air escape portion is provided radially outward from the inner peripheral ridge line of the female screw, thereby forming a kind of labyrinth structure, and an imaging device It prevents dust and unwanted light from entering straight inside. Here, “sealing” means that air leaks from the end of the lens frame when the image sensor (or the substrate on which the image sensor is mounted) is fixed, for example, so as to close the end of the lens frame. It means no state.

According to a second aspect of the present invention, in the invention of the first aspect, the air escape portion includes a flat portion obtained by cutting a part of the male screw in a tangential direction, and a convex formed at the center of the flat portion. It consists of a part.

As the air escape portion, by forming the convex portion on the flat portion, intrusion of dust and unnecessary light can be more effectively suppressed.

According to a third aspect of the present invention, in the invention according to the first or second aspect, the holder is molded using a mold, and the convex portion has a part of the outer periphery of the male screw portion radially inward. It is characterized by a shifted shape.

When forming a helical groove shape corresponding to the male screw portion in the mold for forming the holder, a tool for forming the helical shape is locally shifted inward in the radial direction, Since the convex portion can be formed, the mold can be easily processed.

According to a fourth aspect of the present invention, in the invention according to the third aspect, the mold is processed by electric discharge machining.

When the electrical discharge machining is performed on the spiral groove shape corresponding to the male screw portion, the convex portion can be formed by locally shifting the electrode for machining and forming the spiral shape radially inward. Is easy to process.

The imaging device according to claim 5 is characterized in that, in the invention according to any one of claims 1 to 4, the imaging device is formed through a reflow process. The reflow process is a process in which solder balls or the like between terminals are melted by passing through a high-temperature reflow bath to realize collective connection, and is described in, for example, JP-A-2002-223378.

According to the present invention, it is possible to provide an imaging apparatus that can prevent dust and unnecessary light from entering while ensuring air permeability inside and outside, and can suppress the generation of dust.

It is a perspective view of the imaging device 50 concerning this embodiment. It is the figure which looked at the structure of FIG. 1 from the upper surface. It is sectional drawing which cut | disconnected the structure of FIG. 2 by the arrow III-III line, and looked at the arrow direction. It is a perspective view of the holder 21, and is shown with the jig for adjustment. It is a figure for demonstrating the shaping | molding method of a holder. It is the schematic which shows the manufacturing process of the metal mold | die (a fitting surface is shown in figure) which shape | molds a holder. FIG. 7 is a view showing the holder of FIG. 5 together with the lens frame 22 when viewed in the direction of arrow VII. It is the figure which cut | disconnected the combined holder and the lens frame in a different site | part, and looked at the optical axis direction. It is a figure which shows the state equipped with the imaging device 50 in the mobile telephone 100 as a portable terminal which is a digital apparatus, (a) is a front surface, (b) is a back surface. 3 is a control block diagram of the mobile phone 100. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an imaging apparatus 50 according to the present embodiment, FIG. 2 is a diagram of the configuration of FIG. 1 viewed from above, and FIG. 3 is a diagram of the configuration of FIG. It is sectional drawing cut | disconnected and seen in the arrow direction. As shown in FIGS. 1 to 3, an imaging device 50 includes a CMOS image sensor 51 as a solid-state imaging device having a photoelectric conversion unit 51a, and an imaging lens that causes the photoelectric conversion unit 51a of the image sensor 51 to capture a subject image. OU, a holder 21 that holds the imaging lens OU, a lens frame 22 to which the holder 21 is attached, and a substrate 52 that has an external connection terminal (not shown) that holds the image sensor 51 and transmits and receives electrical signals. These are assembled together through a reflow process.

The image sensor 51 has a photoelectric conversion unit 51a as a light receiving unit in which pixels (photoelectric conversion elements) are two-dimensionally arranged at the center of the light receiving side plane, and a signal processing circuit (not shown). It is connected to the. Such a signal processing circuit includes a drive circuit unit that sequentially drives each pixel to obtain a signal charge, an A / D conversion unit that converts each signal charge into a digital signal, and a signal that forms an image signal output using the digital signal. It consists of a processing unit and the like. A number of pads (not shown) are arranged near the outer edge of the plane on the light receiving side of the image sensor 51, and are connected to the substrate 52 via wires (not shown). The image sensor 51 converts the signal charge from the photoelectric conversion unit 51a into an image signal such as a digital YUV signal, and outputs the image signal to a predetermined circuit on the substrate 52 via a wire (not shown). Here, Y is a luminance signal, U (= RY) is a color difference signal between red and the luminance signal, and V (= BY) is a color difference signal between blue and the luminance signal. Note that the solid-state imaging device is not limited to the CMOS image sensor, and other devices such as a CCD may be used.

The substrate 52 is connected to an external circuit (for example, a control circuit included in a host device of a portable terminal mounted with an imaging device) via an external connection terminal (not shown), and a voltage for driving the image sensor 51 from the external circuit. And a clock signal can be received, and a digital YUV signal can be output to an external circuit.

The hollow rectangular tube-shaped lens frame 22 has a circular hole 22b in which the head 21b of the holder 21 is accommodated in a non-contact manner with a clearance S at the top, and the lower end opens in a rectangular shape to enclose the image sensor 51. On the other hand, the entire surface of the substrate 52 is bonded and sealed, and further has a female screw 22a at the center of the inner periphery. A holder 21 is disposed inside the lens frame 22. An imaging lens OU is bonded and fixed inside the holder 21, and the object side optical surface is exposed from the opening 21 e of the holder 21. The imaging lens OU may be made of plastic, but is preferably made of glass having excellent heat resistance or a WLO (wafer lens having optical surfaces formed on both sides of a transparent substrate) in consideration of the reflow process. The imaging lens OU may be a single lens or a plurality of lenses.

In the conventional imaging apparatus, when measures such as this embodiment described below are not taken, a sealed space is formed between the imaging element and the lens frame (by the threaded male screw 21c and female screw 22a). When the imaging device is heated at the time of reflowing in the sealed internal space A), the bonding process, etc., and the internal pressure in the sealed space increases, the lens frame is deformed or broken. Therefore, in the present embodiment, the internal space of the imaging device is communicated with the outside as described later.

FIG. 4 is a perspective view of the holder 21. 3 and 4, the holder 21 has a trunk portion 21a, a flange-shaped head portion 21b, and a male screw 21c formed on the outer periphery of the trunk portion 21a. A part of the male screw 21c is formed at the center of a D-cut portion (flat portion) 21d (only one is shown in FIG. 4) formed so as to cut the outer periphery by two planes parallel to the axis, and the D-cut portion 21d. And a convex portion 21p. The convex part 21p has such a shape that the outer periphery of the male screw 21c is shifted radially inward. The D cut portion 21d and the convex portion 21p constitute an air escape portion.

Although the details will be described later, the D-cut portion 21d is formed so as to be positioned substantially the same (or slightly radially outside) as the bottom of the male screw 21c on the central parting line PL (FIG. 5) formed at the time of molding. Has been.

Referring to FIG. 3, an opening 21e is formed at the center of the head 21b of the holder 21, and bottomless cutouts 21f and bottomed cutouts 21g are alternately formed at the outer periphery around the opening 21e. Has been. Between the head part 21b and the trunk | drum 21a, the channel | path 21h extended in the circumferential direction and whose outer diameter is smaller than the external thread part 21c is formed. The bottomed notch 21g having the same phase as the D-cut portion 21d has a relatively shallow shape and has a partition 21k at the bottom thereof, and therefore does not communicate with the passage 21h. On the other hand, the bottomless notch 21f out of phase with the D-cut portion 21d has a relatively deep shape and communicates with the passage 21h.

In addition, since the jig JG described later has two claw portions JGa to be engaged with the notches, two bottomless notches 21f are essentially necessary, but the degree of freedom of the engagement angle of the jig JG is sufficient. In order to ensure, it is desirable to provide four cutouts. In that case, in addition to the two bottomless cutouts 21f, a passage 21h is provided so that foreign matter does not enter even if the phase coincides with the D cut portion 21d. Two bottomed cutouts 21g that do not communicate with each other are provided. The number and interval of the cutouts are not limited to the above, and it is sufficient if the bottomless cutout 21f is out of phase with the D cut portion 21d.

Particularly, since the head portion 21b of the holder 21 is in a non-contact state with the lens frame 22, the entire cutout portion may be a bottomed cutout 21g. However, by providing the bottomless notch 21f, more ventilation space can be secured, and furthermore, by providing the bottomless notch 21f, a vent hole is secured, so that the entire circumference of the non-contact portion of the head 21b is secured. It is also effective when attaching an adhesive.

FIG. 5 is a diagram for explaining a method of forming the holder. The hollow cylindrical mold M1 is for molding the head 21b of the holder 21. On the other hand, the half-cylindrical molds M <b> 2 and M <b> 3 form the body portion 21 a of the holder 21. Further, the mold M4 forms the inner peripheral shape of the holder 21. The mold M1 is provided with a protrusion M1a corresponding to the notches 21f and 21g, and a protrusion M1b that forms the opening 21e of the holder 21. The mold M4 is formed with a cylindrical portion M4a that forms the inner periphery of the holder 21.

The molds M2 and M3 are formed with screw forming portions M2a and M3a corresponding to the male screw 21c, and inner peripheral overhanging portions M2b and M3b (see FIG. 6) corresponding to the D-cut portion 21d. With reference to FIG. 6, the electric discharge machining of the screw forming portions M2a and M3a in the molds M2 and M3 will be described. The electric discharge machining electrode T disposed on the inner diameter side of the cylindrical mold material M is formed by the mold. In this case, the electrode T is shifted radially inward at positions corresponding to the inner peripheral overhanging portions M2b and M3b. As a result, when the spiral shape to be processed when the original spiral movement is indicated by a dotted line, the inner peripheral overhanging portions M2b and M3b (shapes complementary to the convex portion 21p in FIG. 4) are formed on the radially inner side. Will be. The dotted lines in FIG. 6 are the shapes of the screw forming portions M2a and M3a formed when the electrode T is not shifted.

In FIG. 5, after the end surfaces of M1 to M4 are brought into contact with each other and clamped, the inside is filled with resin and solidified to form the holder 21. Thereafter, as shown in FIG. 5, the molds M1 and M4 are punched out so as to be separated in the axial direction, and the molds M2 and M3 are punched out along the D-cut portion 21d in the direction orthogonal to the axial line. Accordingly, the parting line PL formed by the molds M2 and M3 crosses the center of the D cut portion 21d and gets over the convex portion 21p, and is generated in parallel to the axis. Thus, the holder 21 is completed.

Thereafter, after the imaging lens OU is bonded and fixed to the holder 21, the male screw 21 c is screwed into the female screw 22 a of the lens frame 22 as shown in FIG. 3. At this time, the jig JG as shown in FIG. The holder 21 can be screwed with respect to the lens frame 22 by rotating the jig JG with the claw portion JGa fitted in the notch 21f or the notch 21g. Is incident on the image sensor for inspection through the imaging lens OU, so that the position of the imaging lens OU in the optical axis direction can be adjusted while viewing the output.

FIG. 7 is a cross-sectional view showing a state in which the holder 21 and the lens frame 22 are assembled at a position corresponding to FIG. FIG. 8 is a view of the D-cut portion 21d as viewed in the optical axis direction, with the left half being cut at the groove bottom of the female screw 22a and the right half being cut at the groove bottom of the male screw 21c. According to the present embodiment, when the holder 21 is screwed into the lens frame 22 while adjusting the position in the optical axis direction of the imaging lens OU, the head 21b of the holder 21 is not in the circular hole 22b of the lens frame 22. Since it is in a contact state, the head 21b and the lens frame 22 do not slide, and generation of dust due to friction can be avoided.

After the position adjustment of the imaging lens OU, the holder 21 is bonded to the lens frame 22. At this time, since the notch 21g is relatively large, it is not blocked even if the adhesive flows. Thereafter, in the reflow process, the lens frame 22 is mounted on the substrate 52 together with the image sensor 51. At this time, the air that has been heated and expanded in the space A (see FIG. 3) in the lens frame 22 has a D-cut portion 21d and a convex portion 21p, and a female screw 22a of the lens frame 22 as shown by dotted lines in FIG. The space C between the lens frame 22, the passage 21h and the bottomless notch 21f (the passage connecting the bottomless notch 21f and the D-cut portion 21d), the head 21b, and the circular hole 22b. Since it escapes to the outside via the clearance S of the whole circumference in the meantime, the internal pressure does not increase and deformation and destruction of each part can be suppressed. Further, if there is a bottomless notch 21f, it escapes more actively from there.

On the other hand, as is apparent from FIG. 8, when the male screw 21c and the female screw 22a are screwed together, the D-cut portion 21d and the convex portion 21p are provided radially outside the inner peripheral ridgeline R of the female screw 22a. As a result, there is no space that can be seen from the other side, so that a kind of maze structure is formed, and even if dust or unnecessary light enters through the gap S, they can enter straight into the lens frame 22. Can be effectively suppressed. The present invention can be similarly applied to a case where a male screw is formed on the imaging lens OU itself without using the holder 21 and is directly screwed to the lens frame 22.

Next, usage modes of the above-described imaging device 50 will be described. FIGS. 9A and 9B are diagrams illustrating a state in which the imaging device 50 is mounted on a mobile phone 100 as a mobile terminal that is a digital device. FIG. 10 is a control block diagram of the mobile phone 100.

The imaging device 50 is disposed, for example, such that the object-side end surface of the imaging lens OU is provided on the back surface of the mobile phone 100 (the liquid crystal display unit 70 side is the front surface) and corresponds to a position below the liquid crystal display unit 70. Is done.

The external connection terminal (not shown) of the imaging device 50 is connected to the control unit 101 of the mobile phone 100 and outputs an image signal such as a luminance signal or a color difference signal to the control unit 101 side.

On the other hand, as shown in FIG. 10, the cellular phone 100 controls each unit in an integrated manner, and also supports a control unit (CPU) 101 that executes a program corresponding to each process, and inputs a number and the like with keys. An input unit 60, a display unit 70 for displaying captured images and videos, a wireless communication unit 80 for realizing various information communications with an external server, a system program and various processing programs for the mobile phone 100, A storage unit (ROM) 91 that stores necessary data such as a terminal ID, and various processing programs and data executed by the control unit 101, processing data, imaging data by the imaging device 50, and the like are temporarily stored. And a temporary storage unit (RAM) 92 used as a work area for storage.

When a photographer holding the mobile phone 100 points the imaging lens OU of the imaging device 50 toward the subject, an image signal of a still image or a moving image is captured by the image sensor 51. When the photographer presses the button BT shown in FIG. 9A at a desired photo opportunity, release is performed, and the image signal is taken into the imaging device 50. The image signal input from the imaging device 50 is transmitted to the control system of the mobile phone 100 and stored in the storage unit 92 or displayed on the display unit 70, and further, video information is transmitted via the wireless communication unit 80. Will be transmitted to the outside.

The present invention is not limited to the embodiments described in the specification, and other embodiments and modifications are included for those skilled in the art from the embodiments and technical ideas described in the present specification. it is obvious. For example, the present invention is effective not only in a reflow process but also in a high temperature environment such as an inspection process.

21 holder 21a body 21b head 21c male screw 21d D cut part 21e opening 21f bottom notch 21g bottom notch 21h passage 21k partition 21k convex part 22 lens frame 50 imaging device 51 image sensor 51a photoelectric conversion part 52 substrate 60 input part 70 Display unit 80 Wireless communication unit 92 Storage unit 100 Mobile phone 101 Control unit BT Button ID Terminal JG Jig JGa Claw M1 Mold M1a Protrusion M2, M3 Mold M2a Male thread forming part M2b, M3b Inner projecting part OU Imaging lens PL Parting line

Claims (5)

An imaging lens;
A holder comprising a head and a torso, and holding the imaging lens;
A lens frame to which the holder is attached;
An image pickup device hermetically attached to the lens frame,
The head of the holder is in a non-contact state with the lens frame, the holder is provided with a male screw around the body portion, the lens frame is provided with a female screw that is screwed into the male screw, A part of the outer periphery is cut to form an air escape portion that communicates the inside and the outside of the lens frame, and the air escape portion is formed when the male screw and the female screw are screwed together. An imaging apparatus, characterized in that the imaging apparatus is provided on a radially outer side than an inner peripheral ridge line. 2. The imaging apparatus according to claim 1, wherein the air escape portion includes a flat portion obtained by cutting a part of the male screw in a tangential direction and a convex portion formed at the center of the flat portion. The imaging apparatus according to claim 1, wherein the holder is formed using a mold, and the convex portion has a shape obtained by shifting a part of the outer periphery of the male screw portion radially inward. . 4. The imaging apparatus according to claim 3, wherein the mold is processed by electric discharge machining. 5. The imaging apparatus according to claim 1, wherein the imaging apparatus is formed through a reflow process.

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