JP2006243351A - Imaging device - Google Patents

Abstract

An image pickup apparatus having an autofocus function suitable for a camera module for a mobile phone or a small digital camera is miniaturized.
A lens barrel 2 in which a lens 1 is housed, an image sensor 5 placed on a surface of a substrate 10 at a position facing the lens 1, and a mirror according to a distance between a subject 7 and the lens 1. In the imaging apparatus including the autofocus mechanism 20 that moves the cylinder 2 in a direction orthogonal to the surface of the substrate 10, the lens barrel 2 is used to block unnecessary external light to the imaging element 5 at the end on the substrate 10 side. A skirt portion 2a is integrally provided. In addition, a spacer 4 is provided for setting the minimum distance between the lens 1 and the image sensor 5 to a predetermined distance.
[Selection] Figure 1

Description

  The present invention relates to an image pickup apparatus that inputs an image of a subject with an image pickup element via a lens assembled in a lens barrel.

FIG. 8 is a cross-sectional view illustrating a schematic configuration of a conventional imaging device disclosed in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2002-27311).
As shown in FIG. 8, Patent Document 1 discloses a lens barrel 2 in which a lens 1 is assembled, a substrate 10 on which an imaging element 5 is mounted (placed), and a method for attaching the lens barrel 2 to the substrate 10. An image pickup apparatus including the holder 30 includes a distance setting unit 40 that sets a distance between the lens 1 and the image pickup element between the substrate 10 and the image pickup element 5. Has been. And in patent document 1, the holder 30 is attached to the state surrounding the image pickup device 5 mounted on the substrate 10, the lens barrel 2 with the lens 1 assembled to the holder 30 is attached by screwing, and the image pickup device 5 is attached. When fine adjustment of the position of the lens 1 is necessary, the optical system is changed when the optical system is changed such as slightly rotating the lens barrel 2 or changing the lens 1 to another lens due to a design change or the like. And adjusting the thickness h of the image pickup device 5 in accordance with the focal position.

The conventional imaging device disclosed in Patent Document 1 described above manually adjusts the focal length of the optical system. However, as a conventional imaging device when an autofocus function is added to this, as shown in FIG. The thing of the structure shown in 9 can be considered.
That is, FIG. 9 is a cross-sectional view conceptually showing a configuration when an autofocus function is further added to the holder 30 in the imaging apparatus having the configuration of FIG.
In the figure, 1 is a lens, 2 is a lens barrel, 5 is an image sensor, 7 is a subject, 10 is a substrate, and 12 is an adjustment ring.
13 is a yoke, 14 is a magnet, 15 is a coil, and 20 is an autofocus mechanism. The autofocus mechanism 20 is composed of a yoke 13, a magnet 14, a coil 15, and the like.
Further, l (small L) is a distance between the lens 1 and the imaging device 5.

Reference numeral 12 denotes an adjustment ring. The adjustment ring 12 is arranged concentrically with a predetermined gap (gap) 12a around a central axis (not shown) of the lens barrel 2 as shown in the figure. It is composed of two cylindrical members integrated at the end on the side.
The lower end of the adjustment ring 12 is in contact with the holder 16, and the lens barrel 2 is attached to the inner peripheral surface of the adjustment ring 12 by screwing.
Further, one end 13a of the yoke 13 is inserted into the gap 12a between the two cylindrical members while the adjustment ring 12 is movable in a direction perpendicular to the substrate 10.
In addition, although the lens 1 has shown the thing of 2 sheet structure, it cannot be overemphasized that the lens of 1 sheet structure may be sufficient.
Further, l (small L) is a distance between the lens 1 and the imaging device 5.

Here, the operation of the autofocus mechanism 20 will be briefly described.
The magnet 14 disposed on the inner circumferential surface of the substantially cylindrical yoke 13 and the coil 15 disposed on the outer circumferential surface of the substantially cylindrical adjusting ring 12 are disposed to face each other. Magnetic field lines are generated across the coil 15.
When a current is passed through the coil 15, a force is applied to the coil 15 according to Fleming's left-hand rule.
For example, when a current is applied to the left coil 15 in the front direction of the paper and a right coil 15 is applied in the direction of the back of the paper surface, the coil 15 is applied in an upward direction (a direction above the substrate 10).
Since the coil 15 is fixed to the adjustment ring 12 and the lens barrel 2 is screwed onto the adjustment ring 12, the lens 1 housed in the lens barrel 2 by the force applied to the coil 15 is directed upward. Move to (z direction).
Accordingly, the focus adjustment (autofocus adjustment) can be performed by adjusting the value of the current flowing through the coil in accordance with the distance to the position of the subject 7.

Now, the reason why the adjustment ring 12 is provided in the conventional imaging apparatus shown in FIG. 9 will be described.
In the case of a small camera module with an autofocus function, in order to reduce the upward movement of the lens 1 (that is, the direction perpendicular to the surface of the substrate 10 on which the image sensor 5 is placed), the autofocus adjustment is performed. It is necessary to manually adjust the focus until focus is achieved at the initial position.
Otherwise, in order to maintain the initial position of the lens 1, it is necessary to keep the current flowing through the coil 15 at all times. In a mobile phone with a small battery capacity or a small digital camera, the remaining capacity of the battery is immediately It decreases and the time that it can operate becomes short.
The adjustment ring 12 is used for mechanical adjustment to the initial position where the focus is in place without applying a current to the coil 15. By screwing the lens barrel 2 into the adjustment ring 12, The position can be adjusted to a predetermined initial position.
JP 2002-027311 A (FIG. 1, paragraph 0009)

As described above, the conventional image pickup apparatus with an autofocus function supports and fixes the screw-type adjustment ring 12 for adjusting the position of the lens 1 to a predetermined initial position, and the adjustment ring 12 as well as from the outside. Since the holder 16 for blocking light is required, it is difficult to reduce the size.
The present invention has been made to solve such problems, and provides a downsized image pickup apparatus with an autofocus function suitable for a camera module for a mobile phone or a small digital camera. Objective.

  An imaging apparatus according to the present invention includes a lens barrel that accommodates a lens, an imaging element that is placed on a substrate surface at a position facing the lens, and the lens barrel that corresponds to a distance between a subject and the lens. In the imaging apparatus having an autofocus mechanism that moves in a direction perpendicular to the substrate surface, the lens barrel has an integrated skirt portion for blocking unnecessary external light to the imaging element at an end portion on the substrate side. Is provided.

  Moreover, the imaging device according to the present invention is provided with a spacer for setting a minimum distance between the lens and the imaging element to a predetermined distance.

  According to the imaging apparatus according to the present invention, the lens barrel is integrally provided with a skirt portion for blocking unnecessary external light to the imaging device at the end on the substrate side. A holder as a separate member for blocking external light to the image sensor is not required, and the apparatus can be miniaturized.

In addition, according to the imaging apparatus according to the present invention, the initial position when the coil current is 0 can be set by the spacer, so the adjustment ring in the conventional apparatus is not necessary,
Furthermore, the apparatus can be miniaturized.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In addition, the same code | symbol represents the same thing or an equivalent thing between each figure.
Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing a schematic configuration of an imaging apparatus according to Embodiment 1 of the present invention.
In FIG. 1, 1 is a lens composed of a single lens or a plurality of lenses, 2 is a lens barrel in which the lens 1 is assembled, 5 is an image sensor, 7 is a subject, 10 is an image sensor 5 mounted (placed). A substrate 20 is an autofocus mechanism 20 for performing autofocus adjustment by moving the lens barrel 2 on which the lens 1 is assembled in a direction orthogonal to the substrate 10.

Reference numeral 4 is fixed to the lowermost surface of the lens 1 (that is, the surface facing the image sensor 5). When the lens 1 approaches the substrate 10 side by the autofocus mechanism 20, the distance between the lens 1 and the image sensor 5 is reached. Is a spacer for restricting the distance from falling below a predetermined distance.
That is, the spacer 4 is a member for setting a minimum distance between the lens 1 and the image sensor 5 to a predetermined distance (a distance between the lens 1 and the image sensor 5 at an initial position described later).
Reference numeral 3 denotes a lens support portion for attaching and supporting the spacer 4 to the inner wall of the lens barrel 2, and the spacer 4 is attached to the lens support portion 3.
In addition, the lens 1 and the lens support part 3 may be formed integrally.

As shown in the figure, the lens barrel 2 is concentrically formed around a first cylindrical portion (not indicated) that houses the lens 1 and a central axis (not shown) of the first cylindrical portion. It has a second cylindrical portion (not indicated) that is disposed, and the second cylindrical portion is integrated with the first cylindrical portion at the end of the first cylindrical portion on the substrate 10 side. Is formed.
The second cylindrical portion disposed on the outer peripheral portion of the lens barrel 2 includes a cylindrical skirt portion 2a formed so as to cover the side surface of the imaging element 5 on the lower end side (substrate 10 side), and the skirt. An outer peripheral cylindrical portion 2 b formed on the outer peripheral portion of the lens barrel 2 so as to extend to the opposite side of the substrate 2 of the portion 2 a is integrally formed.
That is, the second cylindrical portion is composed of the skirt portion 2a and the outer peripheral cylindrical portion 2b.
The skirt portion 2a and the outer cylindrical portion 2b constituting the second cylindrical portion are formed concentrically with the central axis (not shown) of the lens barrel 2, and further, the first cylindrical portion of the lens barrel 2 is A predetermined gap 2c is provided between the outer peripheral surface and the inner peripheral surface of the outer cylindrical portion 2b.

In the above description, the shape of the skirt portion 2a is a cylindrical shape, but the shape of the skirt portion 2a may be a rectangular tube shape formed so as to cover the side surface of the rectangular imaging element 5.
Since the outer shape of the image pickup device 5 is usually a quadrangular shape, it is more advantageous to reduce the size of the apparatus if the shape of the skirt portion 2a is a square cylindrical shape matching the outer shape of the image pickup device 5.
Further, 13 is a yoke, 14 is a magnet disposed on the inner peripheral surface of the yoke 13, 15 is a coil disposed on the outer peripheral surface of the outer peripheral cylindrical portion 2b of the lens barrel 2, and 20 is an autofocus mechanism. 20 includes a yoke 13, a magnet 14, a coil 15, and the like.
The yoke 13 has a substantially cylindrical shape, and the end on the substrate 10 side is fixed to the substrate 10.
Further, the end 13a on the other end side of the yoke 13 is such that the lens barrel 2 is movable in a direction orthogonal to the substrate 10, and the outer peripheral surface of the first cylinder portion of the lens barrel 2 and the second cylinder portion. Is inserted into the gap 2c between the outer peripheral cylindrical portion 2b and the inner peripheral surface.

Here, a schematic operation of the autofocus mechanism 20 will be described.
The magnet 14 fixed to the inner peripheral surface of the substantially cylindrical yoke 13 and the coil 15 fixed to the outer peripheral surface of the outer peripheral cylindrical portion 2b of the lens barrel 2 are arranged to face each other. Magnetic field lines are generated across the coil 15.
When a current flows through the coil 15, a force is applied to the coil 15 according to Fleming's left-hand rule.
For example, when a current is applied to the left coil 15 in the front direction of the paper and a right coil 15 is applied in the direction of the back of the paper surface, the coil 15 is applied in an upward direction (a direction above the substrate 10).
Since the coil 15 is fixed to the outer peripheral surface of the outer peripheral cylindrical portion 2b of the lens barrel 2, the lens 1 in the lens barrel 2 moves upward (z direction) by the force applied to the coil 15. Therefore, the focus adjustment can be performed by adjusting the value of the current flowing through the coil in accordance with the distance to the position of the subject 7.

FIG. 2 is an operation flowchart for explaining the autofocus operation of the imaging apparatus according to the present embodiment.
FIG. 3 is a diagram illustrating a state of the imaging device when an electric current flows through the coil 15 and the lens barrel 2 moves upward and an autofocus operation is performed.
FIG. 4 is a diagram showing the relationship between the coil current and the moving distance of the lens barrel 2, and shows that the moving distance of the lens barrel 2 increases as the current I flowing through the coil 15 increases.
FIG. 5 is a diagram showing the relationship between the moving distance of the lens barrel 2 and the subject distance (that is, the distance between the uppermost surface of the lens barrel 2 and the subject 7). In order to focus, the smaller the subject distance, It shows that the moving distance required for the lens barrel 2 increases and the current I flowing through the coil 15 also increases.

The operation of the imaging layer according to the present embodiment will be described with reference to FIGS.
FIG. 1 shows a state in which the current flowing through the coil 15 is zero, and the lens 1 in the lens barrel 2 is located at the lowermost portion regulated by the spacer 4 and is closest to the image sensor 5. .
That is, when the autofocus operation is not performed and the current flowing through the coil 15 is 0, the distance between the lowermost surface of the lens 1 in the lens barrel 2 and the upper surface of the image sensor 5 is set to a predetermined value by the spacer 4. Set to the initial position.
In the drawing, l (small L) indicates a distance (minimum distance) between the lowermost surface of the lens 1 and the upper surface of the image sensor 5 at the initial position.

As shown in FIG. 2, before starting the autofocus operation, the camera (that is, the imaging device) is turned on, but the current flowing through the coil 15 is 0, and the lens barrel 2 is moved by the spacer 4. It is set to a predetermined initial position to be regulated. (Step S1)
Thus, although the camera (imaging device) is ON at the initial position, the current flowing through the coil 15 is set to 0 in order to suppress power consumption.
In other words, the initial position is the position of the lens barrel 2 when the camera (imaging device) is turned on but the subject 7 is not photographed and the autofocus operation is not yet performed.

Next, in order to photograph the target subject 7, the camera (imaging device) is pointed at the subject 7, the autofocus mechanism 20 is operated, and the lens barrel 2 is moved to the in-focus position. (Step S2)
Assuming that the current flowing through the coil 15 at this time is I, the current I flowing through the coil 15 varies depending on the subject distance, the moving distance from the initial barrel position is determined by the subject distance, and the moving distance from the initial barrel position is There is a correlation with the current.
Next, when the coil current Ip suitable for the state in which the camera is in focus is caused to flow through the coil 15 by the autofocus mechanism 20, the lens barrel 2 moves to the focus position, and the subject 7 is photographed. (Step S3)
After the completion of photographing, the lens barrel 2 returns to the initial position, and the current flowing through the coil 15 becomes zero. (Step S4)

As described above, FIG. 1 shows a state in which the lens barrel 2 is closest to the image sensor 5, and the distance l (small L) between the lowermost part of the lens 1 and the image sensor 5 is A spacer 4 extending from the end of the lens 1 is determined in contact with the surface of the image sensor 5.
At this time, the current flowing through the coil 15 is 0, and neither the camera (imaging device) nor the autofocus operation is performed. For example, if an image can be monitored with a liquid crystal monitor, the infinite distance is in focus. desirable.
The reason is that the subject 7 at a relatively large distance is captured with low-order blur.
Note that, except for the best subject distance, blurring occurs more or less, but the blurring that occurs when the coil current is zero when the blur level becomes smaller with each subject distance is referred to as “low blur”.

The side surface of the image sensor 5 is covered with a skirt portion 2 a extending from the lower end of the lens barrel 2, and the skirt portion 2 a arrives at the image sensor 5 through the lens 1 housed in the lens barrel 2. Blocks everything except light.
FIG. 3 is a diagram illustrating a state of the imaging apparatus when an electric current flows through the coil 15 and the lens barrel 2 moves upward to perform an autofocus operation. The lens barrel 2 is directed toward the subject 7. The spacer 4 and the surface of the image sensor 5 are not in contact with each other.
At this time, the current I flows through the coil 15 of the autofocus mechanism 20, and the autofocus mechanism 20 is operated by the thrust, so that the lens barrel 2 is moving to the optimum position or at the optimum position.
Even at this time, the end of the skirt portion 2a on the side of the substrate 10 is at a position lower than the upper surface of the image pickup device 5, and unnecessary light other than the light reaching the image pickup device 5 through the lens 1 housed in the lens barrel 2. Is shut off.

As described above, the imaging apparatus according to the present embodiment includes the lens barrel 2 that houses the lens 1, the imaging element 5 that is placed on the surface of the substrate 10 at a position facing the lens 1, and the subject 7. In an imaging apparatus including an autofocus mechanism 20 that moves the lens barrel 2 in a direction orthogonal to the surface of the substrate 10 in accordance with the distance between the lenses 1, the lens barrel 2 is connected to the imaging element at the end on the substrate 10 side. A skirt portion 2a for blocking unnecessary external light is integrally provided.
Therefore, according to the imaging apparatus according to the present invention, the lens barrel is integrally provided with the skirt portion for blocking unnecessary external light to the imaging device at the end portion on the substrate side, so that the lens barrel is supported. At the same time, a holder as a separate member for blocking external light to the image sensor is not required, and the apparatus can be reduced in size and cost.

  In addition, since the imaging device according to the present embodiment is provided with the spacer 4 for setting the minimum distance between the lens 1 and the imaging device 5 to a predetermined distance, the initial value when the coil current is 0 by the spacer 4 is provided. The position can be set, the adjustment ring in the conventional apparatus is not necessary, and the apparatus can be further downsized.

  Further, since the spacer 4 of the imaging device according to the present embodiment is attached to the lens support 3 for attaching the lens 1 to the inner wall of the two lens barrels, the initial position tolerance when the coil current is zero is reduced. And low-order blur can be reduced.

Embodiment 2. FIG.
FIG. 6 is a cross-sectional view showing a schematic configuration of an imaging apparatus according to Embodiment 2 of the present invention.
FIG. 7 is a diagram illustrating a state of the imaging apparatus according to the second embodiment when an electric current flows through the coil, the lens barrel moves upward, and an autofocus operation is performed.
6 and 7, reference numeral 9 denotes a spacer (corresponding to the spacer 4 in the first embodiment) used in the imaging apparatus according to the present embodiment.
As shown in FIGS. 6 and 7, the configuration of the imaging apparatus according to the present embodiment and the configuration of the imaging apparatus according to the first embodiment described above are basically the same except for the shape and mounting position of the spacer. However, in the image pickup apparatus according to the present embodiment, the spacer 9 for restricting the distance between the lens 1 and the image pickup element 5 from being a predetermined distance or less is provided at the end of the lens barrel 2 on the substrate 10 side. It is characterized in that it is mounted opposite to the image sensor 5.

In the imaging apparatus according to the present embodiment, as shown in FIG. 6, the spacer 9 extending from the bottom (end) of the lens barrel 2 toward the substrate 10 contacts the surface of the imaging element 5, and the lens 1 and the imaging element A distance 1 (small L) of 5 is determined.
The spacer 9 is formed integrally with the lens barrel 2.
FIG. 7 shows a state in which the current I is passed through the coil 15 and the lens barrel 2 is moving in the direction of the subject 7.
As in the case of the first embodiment, the side surface of the imaging element 5 is covered with a skirt portion 2a extending from the lower end portion of the lens barrel 2, and the skirt portion 2a is accommodated in the lens barrel 2. The light other than the light arriving at the image sensor 5 through the lens 1 is blocked.

  As described above, the spacer 9 of the imaging apparatus according to the present embodiment is attached to the imaging element 5 at the end of the lens barrel 2 on the substrate 10 side, so that the size and cost of the apparatus can be reduced. And low-order blur can be reduced.

  The present invention is useful for realizing a miniaturized imaging apparatus suitable for application to a form phone or a small digital camera.

1 is a cross-sectional view illustrating a schematic configuration of an imaging apparatus according to Embodiment 1. FIG. FIG. 6 is an operation flowchart for explaining an autofocus operation of the imaging apparatus according to the first embodiment. 6 is a cross-sectional view illustrating a state of the imaging apparatus when the imaging apparatus according to Embodiment 1 performs an autofocus operation. FIG. It is a figure which shows the relationship between a coil current and the moving distance of a lens-barrel. It is a figure which shows the relationship between the moving distance of a lens-barrel, and object distance. 4 is a cross-sectional view illustrating a schematic configuration of an imaging apparatus according to Embodiment 2. FIG. FIG. 10 is a cross-sectional view illustrating a state of the imaging apparatus when the imaging apparatus according to Embodiment 2 is performing an autofocus operation. It is sectional drawing which shows schematic structure of the conventional imaging device which does not have an autofocus mechanism. It is sectional drawing which shows schematic structure of the conventional imaging device which has an auto-focus mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens 2 Lens barrel 2a Skirt part 2b Outer cylindrical part 2c Gap 3 Lens support part 4 Spacer 5 Image sensor 7 Subject 9 Spacer 10 Substrate 13 Yoke 14 Magnet 15 Coil 20 Autofocus mechanism

Claims (4)

A lens barrel containing the lens, an image sensor placed on the substrate surface at a position facing the lens, and the lens barrel in a direction orthogonal to the substrate surface according to the distance between the subject and the lens In an imaging device having an autofocus mechanism to move,
The image pickup apparatus, wherein the lens barrel is integrally provided with a skirt portion for blocking unnecessary external light to the image pickup device at an end portion on the substrate side.   The image sensor according to claim 1, further comprising a spacer for setting a minimum distance between the lens and the image sensor to a predetermined distance.   The imaging device according to claim 2, wherein the spacer is attached to a lens support portion for attaching the lens to an inner wall of the lens barrel.   The image pickup device according to claim 2, wherein the spacer is attached to face the image pickup device at an end of the lens barrel on the substrate side.

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