JP7403612B1 - Imaging devices and electronic equipment - Google Patents

Abstract

An imaging device and an electronic device are provided. An imaging device includes a first lens group with positive power, a second lens group with negative power, and an imaging element for image formation from the object side to the image side in the optical axis direction. A housing for moving and driving the first lens group in the optical axis direction, further including a variable focus lens located between the first lens group and the second lens group or closest to the object side of the first lens group. It has a body. A pusher that contacts the housing is provided outside the variable focus lens and drives the variable focus lens and the first lens group to move. In addition, the following conditional expression is satisfied. a<f1/f<b, Δp/Δz>1, 0.5<L/Lp<2 where f1: focal length of the first lens group, f: focal length of the imaging device, 0<a <1 and 1<b<2, △z: amount of movement of the first lens group in the optical axis direction, △p: amount of focus movement relative to the amount of movement of the first lens group in the optical axis direction, L: amount of movement of the first lens group in the optical axis direction. Amount of movement of the first lens group, Lp: amount of push of the pusher. [Selection diagram] Figure 1

Description

The present invention relates to the technical field of optical elements, and particularly to imaging devices and electronic equipment.

Normally, when focusing a lens, one or more lens focus groups are moved in the optical axis direction to focus from infinity to a short distance. At this time, it is necessary to secure a plurality of spaces for the focus group to move in the optical axis direction, and the shorter the minimum photographing distance, the longer the stroke of the focus group becomes and the size becomes larger.

To solve this problem, there is a method of using a variable focus lens to focus from infinity to short distances without moving the focus group in the optical axis direction. By using this method, the problem of increasing the size due to lens focus can be solved. However, the optical power of a variable focus lens is generally inferior to the lens focus, and when focusing over a wide range from infinity to short distances, a single variable focus lens often lacks optical power. Furthermore, in the case of a configuration with only one focus group, it becomes difficult to maintain resolution performance (especially spherical aberration, curvature of field, and chromatic aberration).

If a plurality of variable focus lenses are arranged, the aberrations generated when the object distance changes will reinforce each other, making it difficult to maintain high performance.

Therefore, a combination of lens focus and variable focus lenses may be considered. In this case, the movement space in the optical axis direction is smaller than when using multiple focusing lenses, and the problem of interference between lenses is solved, but it requires two actuators, one for lens focusing and one for variable focus lens. This makes it larger.

At least one embodiment of the present invention provides an imaging device and an electronic device in order to solve the problem of increasing the size of the imaging device when a variable focus lens and a lens focus are used together.

In order to solve the above-mentioned technical problem, the present invention is realized as follows.

As a first aspect, the embodiment of the present invention includes a first lens group having a positive power, a second lens group having a negative power, and an image sensor for imaging from the object side in the optical axis direction. Provided is an imaging device that includes a side. The imaging device further includes a variable focus lens provided in the optical axis direction. The variable focus lens is located between the first lens group and the second lens group, or located closest to the object side of the first lens group. The first lens group has a housing portion for moving and driving the first lens group in the optical axis direction. A pusher that contacts the housing portion is provided outside the variable focus lens. The pusher moves and drives the variable focus lens and the first lens group. Here, the imaging device satisfies the following conditional expression.
a<f1/f<b
△p/△z>1
0.5<L/Lp<2
here,
f1: focal length of the first lens group,
f: focal length of the imaging device;
0<a<1 and 1<b<2,
Δz: amount of movement of the first lens group in the optical axis direction,
Δp: the amount of focus movement on the imaging surface with respect to the movement amount Δz of the first lens group in the optical axis direction,
L: amount of movement of the first lens group;
Lp: Pushing amount of the pusher.

As a second aspect, embodiments of the present invention provide an electronic device including the above-described imaging device.

Compared to the prior art, the imaging device according to the embodiment of the present invention has a variable focus lens that does not move in the optical axis direction inside the imaging device and uses it together with the lens focus, and can change the focus between the variable focus lens and the lens focus with one pusher. By driving two types of lenses, it is possible to downsize the structure of the imaging device.

FIG. 1 is a first diagram showing the configuration of an imaging device according to an embodiment of the present invention. FIG. 2 is a second diagram showing the configuration of an imaging device according to an embodiment of the present invention. FIG. 3 is a third diagram showing the configuration of an imaging device according to an embodiment of the present invention. FIG. 4 is a fourth diagram showing the configuration of an imaging device according to an embodiment of the present invention. It is a figure showing the force given to a pusher. FIG. 5 is a fifth diagram illustrating the configuration of an imaging device according to an embodiment of the present invention. FIG. 6 is a sixth diagram illustrating the configuration of an imaging device according to an embodiment of the present invention. FIG. 5 is a diagram showing various aberrations when the object distance is infinite in the imaging device corresponding to the embodiment of FIG. 4; 5 is a diagram showing various aberrations at close range of the imaging device corresponding to the example of FIG. 4. FIG. FIG. 8 is a diagram showing various aberrations when the object distance is infinite in the imaging device corresponding to the embodiment of FIG. 7; 8 is a diagram showing various aberrations at close range of the imaging device corresponding to the example of FIG. 7. FIG.

Hereinafter, technical means in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments that can be made by those skilled in the art based on the embodiments in this application without any creative work shall fall within the protection scope of this application.

The terms "first", "second", etc. in the specification and claims of this application are used to distinguish between similar objects, and are not necessarily used to explain a particular order or priority. . It is to be understood that the data so used may be interchanged as appropriate so that the embodiments of the present application may be practiced in other orders than as illustrated or described herein, and that the terms "first", " Objects that are distinguished by ``second'' and the like are usually of the same type, and the number of objects is not limited. For example, there may be one or more first objects. Note that "and/or" in the specification and claims represents at least one connection target. The character "/" generally indicates that the related objects before and after are in an "or" relationship.

In order to make the technical means related to the present invention easier to understand, related concepts according to the present invention will be explained below.

The variable focus lens described in the embodiments of the present invention is a liquid lens or a film lens that deforms the lens by applying external pressure without physically moving the lens in the optical axis direction.

As shown in FIGS. 1-7, embodiments of the present invention provide an imaging device. The imaging device includes, from the object side to the image side in the optical axis direction, a first lens group 1, a second lens group 2, and an imaging element 3 for imaging. The first lens group 1 has positive power, and the second lens group has negative power.

Here, the image sensor 3 is a photosensitive element such as an image sensor.

Specifically, the first lens group 1 has positive power as a whole, and all or part of the lenses move in the optical axis direction when the object distance changes, and have positive power. .

The imaging device further includes a variable focus lens 4 provided in the optical axis direction. The variable focus lens is located between the first lens group 1 and the second lens group 2, as shown in FIG. 4, or located closest to the object side of the first lens group 1, as shown in FIG. do. The first lens group 1 has a housing section 5 for moving and driving the first lens group 1 in the optical axis direction. A pusher 6 that contacts the housing portion 5 is provided outside the variable focus lens 4 . The pusher 6 drives the variable focus lens 4 and the first lens group 1 to move.

A voice coil motor (VCM) is selectively fitted into the housing 5 and drives the first lens group 1 to move in the optical axis direction. Referring to FIG. 1, the voice coil motor is mainly composed of a coil 7, a magnet 8, and a spring 9. The coil 7 is fixed inside a magnet 8 by two upper and lower springs 9. Ru. When the coil 7 is energized, a magnetic field is generated in the coil 7. The interaction between the coil magnetic field and the magnet 8 causes the coil 7 to move upwards and the first lens group 1 within the coil 7 to move with it. When the power is turned off, the coil 7 returns due to the elasticity of the spring 9. In this way, an automatic focusing function is realized.

Here, the imaging device satisfies the following conditional expression.
a<f1/f<b
△p/△z>1
0.5<L/Lp<2
here,
f1: focal length of the first lens group 1,
f: focal length of the imaging device,
0<a<1 and 1<b<2,
Δz: amount of movement of the first lens group 1 in the optical axis direction,
Δp: amount of focus movement on the imaging surface with respect to movement amount Δz of the first lens group 1 in the optical axis direction,
L: amount of movement of the first lens group 1;
Lp: Push amount of pusher 6.

In one alternative embodiment, the pusher 6 and the housing part 5 are coupled directly or via a mechanism having a reduction ratio. For example, the mechanism having a reduction ratio is a gear. In addition, in order to simply adjust the push amount of the pusher, the pusher 6 and the housing portion 5 are directly interlocked, that is, the reduction ratio is 1.

Optionally, the variable focus lens 4 is sealed with an optical fluid. The refractive index can be varied by applying pressure to the variable focus lens 4 from the outside via the pusher 6 and deforming the variable focus lens 4 without moving it in the optical axis direction.

Further, the pushing amount of the pusher 6 is determined by the optical fluid or the area of the pusher 6. That is, the pushing amount of the pusher 6 is adjusted by the optical fluid of the variable focus lens 4, the area of the pusher 6, etc.

Referring to FIG. 5, which is a diagram showing the force applied to the pusher, the horizontal axis in the diagram shows the force applied to the pusher, the unit is g/mm2, and the vertical axis shows the deviation/opening area, the unit is g/mm2. m/mm2. It is desirable to adjust the shape of the pusher and the viscosity of the material. Design to keep the thrust below the selected actuator.

Optionally, the variable focus lens 4 is a membrane lens or a liquid lens.

In one preferred embodiment of the present invention, as shown in FIGS. 1 to 4, when the variable focus lens 4 is located between the first lens group 1 and the second lens group 2, 0.5 <f1/f<1.5 is satisfied.

Furthermore, the maximum effective light beam diameter of the variable focus lens 4 is smaller than the maximum effective light beam diameter of the first lens group 1.

The imaging device further satisfies 0.4<Φ/Φ1<0.95 (here, Φ: maximum effective ray diameter of the variable focus lens 4, Φ1: maximum effective ray diameter of the first lens group 1). is preferred.

As shown in FIG. 4, when the variable focus lens 4 is located between the first lens group 1 and the second lens group 2, the lens group on the object side of the variable focus lens 4, that is, the first lens group 1 has a positive power, the light beam at the peripheral image height approaches the light beam at the central image height, and the effective light beam diameter of the variable focus lens 4 can be made smaller than the effective light beam diameter of the first lens group 1. By reducing the effective beam diameter of the variable focus lens 4, it is possible to reduce the size of the variable focus lens 4, thereby achieving cost reduction and high-speed response, as well as miniaturization of the drive element.

Since the peripheral rays are closer to the axial rays passing through the variable focus lens 4 than when the lens is placed near the first lens group 1, it is possible to suppress the occurrence of field curvature when the curvature of the variable focus lens 4 changes. It becomes possible.

By arranging the second lens group 2 on the image side of the variable focus lens 4 and making its power negative, it is possible to increase the focus sensitivity of the variable focus lens, shorten the stroke, and shorten the minimum shooting distance. becomes.

When the upper limit of the conditional expression 0.5<f1/f<1.5 is exceeded, the positive power of the first lens group 1 is too weak and the entire imaging device becomes large. On the other hand, when the lower limit of the conditional expression 0.5<f1/f<1.5 is exceeded, the positive power of the first lens group 1 becomes too strong, causing performance deterioration of the imaging device when the object distance changes. growing. Furthermore, the precision required when assembling the lens becomes higher, which increases the difficulty of manufacturing.

Note that by satisfying the lower limit of the conditional expression Δp/Δz>1, the minimum photographing distance can be shortened without extending the focus stroke more than necessary.

If the upper limit of the conditional expression 0.4<Φ/Φ1<0.95 is exceeded, the diameter of the variable focus lens 4 is insufficiently reduced relative to the effective light beam diameter of the imaging device, leading to increased costs and the overall size of the imaging device. invites change. On the other hand, if the lower limit of the conditional expression 0.4<Φ/Φ1<0.95 is exceeded, the power of the first lens group 1 is too strong, or the length of the first lens group 1 in the optical axis direction is too long. , which leads to an increase in the size of the entire imaging device.

If the upper limit of 0.5<L/Lp<2 is exceeded, the stroke of the first lens group 1 will be extended, resulting in an increase in size. Furthermore, a mechanism having a reduction ratio such as a gear becomes complicated. If it is less than the lower limit of 0.5<L/Lp<2, the variable focus lens 4 is sensitive to the movement of the first lens group 1, which increases assembly precision during manufacturing and makes it difficult to control the variable focus lens. becomes.

In addition, by integrating the housing section 5 that drives the first lens group 1 to move in the optical axis direction and the pusher 6 of the variable focus lens 4, the size of the imaging device can be reduced by about 15% as a whole, and consumption can be reduced. A power saving effect of approximately 220 mW is expected. Furthermore, since the number of parts is reduced, costs can be reduced, and the number of steps for assembling the pusher can be reduced in the manufacturing process, improving yield.

In another preferred embodiment of the present invention, referring to FIGS. 6 and 7, when the variable focus lens 4 is located closest to the object side of the first lens group 1, 0.6<f1/f<1 .2 is satisfied.

Here, the variable focus lens 4 is located closest to the object side of the first lens group 1. By arranging the variable focus lens 4 closest to the object side of the imaging device, manufacturing and assembly is facilitated, and replacement in the event of a defect in the variable focus lens 4 is also simple, reducing the difficulty in assembling the lens and the manufacturing cost. There are benefits.

If the lower limit of the conditional expression 0.6<f1/f<1.2 is exceeded, the positive power of the first lens group 1 becomes too strong, making it difficult to correct aberrations and further reducing the required accuracy when assembling the lens. This makes it difficult to achieve high performance. On the other hand, if the upper limit of the conditional expression 0.6<f1/f<1.2 is exceeded, the focus stroke becomes long, making it difficult to downsize the entire imaging device.

In this embodiment, when the first lens group 1 and the second lens group 2 on the image side of the variable focus lens 4 are all used as a focus, the value of △p/△z is 1, but the value of △p/△z is 1. When the second lens group 2 located on the image side of the first lens group 1 has negative power, by satisfying the conditional expression △p/△z>1, the focus stroke can be shortened, resulting in improved imaging. Contributes to downsizing of equipment.

Furthermore, when the first lens group 1 and the second lens group 2 on the image side of the variable focus lens 4 are all used as a focus, the curvature of field that occurs in the variable focus lens 4 when the object distance changes, Since the directions of fluctuations in the field curvature that occur in the lens focus (first lens group 1, second lens group 2) are the same, it is difficult to improve performance especially when the shooting distance is shortened, and it is difficult to achieve compactness and It becomes difficult to achieve both high performance and a shortened minimum shooting distance.

In addition, as in the above embodiment, since the pusher 6 of the variable focus lens is pushed in as shown in FIG. 2, if the upper limit of the conditional expression 0.5<L/Lp<2 is exceeded, the first lens group This causes the stroke of step 1 to be extended, resulting in an increase in size. Furthermore, unlike the above embodiments, the positions of the first lens group 1 and the variable focus lens 4 are reversed, making it difficult to avoid interference between the lenses. On the other hand, when the conditional expression 0.5<L/Lp<2 is less than the lower limit, the variable focus lens 4 is sensitive to the movement of the first lens group 1, and the assembly precision in manufacturing increases, and the variable focus lens becomes difficult to control.

As for the expected effects, by integrating the pusher, it is expected that the overall size will be reduced by about 10% and power consumption will be reduced to about 220 mW.

In one embodiment of the invention, the first lens group 1 includes at least one lens, and the second lens group 2 includes at least one lens, the lenses of the first lens group 1 and the The lenses of the second lens group 2 are all aspheric lenses.

Note that the aspherical type used for the lens of the imaging device according to the embodiment of the present invention is defined as follows.
Here, x is the sag amount, y is the height from the optical axis, c is the paraxial curvature of the aspherical surface, and is the reciprocal of the radius of curvature of the aspherical surface, and k is the conic constant of the aspherical surface, and An is the nth-order aspherical coefficient.

Hereinafter, specific implementation parameters of the lens of the imaging device according to the embodiments of the present invention will be explained in detail through four embodiments.
Example 1

Referring to the structure of the lens in the imaging device of FIG. 4, the refractive index, Abbe number, and focal length of the lens are all based on a light beam with a wavelength of 555.00 nm.

In Example 1, the value of f1/f is 0.883, the value of Δp/Δz is 1.439, and the value of Φ/Φ1 is 0.657.

Here, Table 1 is lens data corresponding to the structure of the lens in the imaging device of FIG. 4, Table 2 is each aspheric coefficient corresponding to the lens in the imaging device of FIG. The optical parameters of the imaging device shown in FIG. 4 are shown at infinite distance and close distance (30 mm). Table 4 shows the distance between the lens focus (first lens group) and the variable focus lens at an object distance of infinity and 30 mm.

Here, f indicates the focal length of the imaging device, Fno indicates the aperture value of the imaging device, ω indicates the angle of view, and Y indicates the image height.

Here, each lens in the imaging device adopts the size range in Example 1 above. Of FIG. 8, FIG. 8A shows a curve of astigmatism when the object distance is infinite (in this drawing, the abscissa indicates the magnitude of astigmatism, the unit is mm, and the ordinate is (indicates angle of view). FIG. 8B shows the curve of spherical aberration when the object distance is infinite (in the figure, the abscissa indicates the spherical aberration in mm, and the ordinate indicates the aperture value). FIG. 8C shows a distortion aberration curve when the object distance is infinite (in the figure, the abscissa indicates the magnitude of distortion, expressed in %, and the ordinate indicates the angle of view).

Of FIG. 9, FIG. 9A shows a curve of astigmatism when the object distance is close (in the drawing, the abscissa indicates the magnitude of the astigmatism, the unit is mm, and the ordinate indicates the image (indicates a corner). FIG. 9B shows a curve of spherical aberration at close object distance (in the figure, the abscissa indicates the spherical aberration in mm, and the ordinate indicates the aperture value). FIG. 9C shows a curve of distortion aberration at close object distance (in the figure, the abscissa indicates the magnitude of distortion, expressed in %, and the ordinate indicates the angle of view).

8 and 9 show various aberrations at the object distance ∞ and close range in Example 1 shown in FIG. 4. It can be seen that high performance can be maintained from infinity to close range by canceling the aberration (field curvature) generated by the variable focus lens 4 and the first lens group 1.
Example 2

Referring to the structure of the lens in the imaging device of FIG. 7, the refractive index, Abbe number, and focal length of the lens are all based on a light beam with a wavelength of 555.00 nm. In Example 2, the value of f1/f is 0.922, and the value of Δp/Δz is 1.180. Here, Table 5 is lens data corresponding to the structure of the lens in the imaging device of FIG. 7, Table 6 is each aspheric coefficient corresponding to the lens in the imaging device of FIG. The optical parameters of the imaging device shown in FIG. 7 are shown at infinite distance and at close distance (30 mm). Table 8 shows the distance between the lens focus and the variable focus lens when the object distance is infinite and close distance (30 mm), and the distance between the lens focus and the second lens group when the object distance is infinite and close distance (30 mm).

Here, each lens in the imaging device adopts the size range in Example 2 above. Of FIG. 10, FIG. 10A shows a curve of astigmatism when the object distance is infinite (in this drawing, the abscissa indicates the magnitude of astigmatism, the unit is mm, and the ordinate is (indicates angle of view). FIG. 10B shows a curve of spherical aberration at an infinite object distance (in the figure, the abscissa indicates the spherical aberration, in mm, and the ordinate indicates the aperture value). FIG. 10C shows a distortion aberration curve when the object distance is infinite (in the drawing, the abscissa indicates the magnitude of distortion, expressed in %, and the ordinate indicates the angle of view).

Of FIG. 11, FIG. 11A shows a curve of astigmatism when the object distance is close (in the drawing, the abscissa indicates the magnitude of astigmatism, the unit is mm, and the ordinate indicates the image (indicates a corner). FIG. 11B shows the curve of spherical aberration at close object distance (in the figure, the abscissa indicates the spherical aberration in mm, and the ordinate indicates the aperture value). FIG. 11C shows a distortion aberration curve at close object distance (in the figure, the abscissa indicates the magnitude of distortion, expressed in %, and the ordinate indicates the angle of view).

10 and 11 show various aberrations at the object distance ∞ and close range in Example 2 shown in FIG. 7. It can be seen that high performance can be maintained from infinity to close range by canceling the aberration (field curvature) generated by the variable focus lens 4 and the first lens group 1.

In the present invention, it is assumed that a variable focus lens and a lens focus are used together, and when the pusher for driving the lens focus and the variable focus lens is integrated, the minimum It is possible to achieve both shorter shooting distance, smaller size, and higher performance.

Furthermore, embodiments of the present invention further provide electronic equipment including the imaging device described above.

The above-mentioned imaging lens is also used in an imaging device for a portable information device such as a so-called smart phone, a so-called feature phone, or a tablet device.

An electronic device in an embodiment of the invention may be a mobile electronic device or a non-mobile electronic device. For example, mobile electronic devices include mobile phones, tablet computers, notebook computers, palm computers, in-vehicle electronic devices, wearable devices, ultra-mobile personal computers (UMPCs), netbooks, or personal digital assistants (PDAs). ), and non-mobile electronic devices include servers, network attached storage (NAS), personal computers (PCs), televisions (TeleVision), ATMs or self-service machines, etc. Examples of the present invention are non-limiting.

Although the embodiments of the present invention have been described above based on the drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are illustrative and not limiting. Many forms that a person skilled in the art can make based on the suggestion of the present invention without departing from the spirit of the present invention and the scope of the claims are all included within the protection scope of the present invention.

Claims (10)

An imaging device,
Consisting of a first lens group with positive power, a second lens group with negative power, and an imaging device for imaging , which are arranged in order from the object side to the image side in the optical axis direction,
further comprising a variable focus lens provided in the optical axis direction,
The variable focus lens is located between the first lens group and the second lens group, or located closest to the object side of the first lens group,
The first lens group has a housing portion for moving and driving the first lens group in the optical axis direction,
A pusher that contacts the housing portion is provided on the outside of the variable focus lens, and
the pusher moves and drives the variable focus lens and the first lens group;
The variable focus lens is sealed with an optical fluid, and the variable focus lens is deformed by applying pressure to the variable focus lens from the outside via the pusher,
The imaging device includes:
a<f1/f<b
△p/△z>1
0.5<L/Lp<2
(f1: focal length of the first lens group,
f: focal length of the imaging device;
0<a<1 and 1<b<2,
Δz: amount of movement of the first lens group in the optical axis direction,
Δp: the amount of focus movement on the imaging surface with respect to the movement amount Δz of the first lens group in the optical axis direction,
L: amount of movement of the first lens group;
Lp: amount of pushing of the pusher). The imaging device according to claim 1,
When the variable focus lens is located between the first lens group and the second lens group,
It is characterized by satisfying 0.5<f1/f<1.5. The imaging device according to claim 2,
A maximum effective light beam diameter of the variable focus lens is smaller than a maximum effective light beam diameter of the first lens group. The imaging device according to claim 3,
0.4<Φ/Φ1<0.95
(Φ: maximum effective light beam diameter of the variable focus lens,
Φ1: maximum effective light beam diameter of the first lens group). The imaging device according to claim 1,
When the variable focus lens is located closest to the object side of the first lens group,
It is characterized by satisfying 0.6<f1/f<1.2. The imaging device according to claim 1,
The pusher and the casing are connected directly or through a mechanism having a reduction ratio. The imaging device according to claim 1 ,
The pushing amount of the pusher is determined by the area of the optical fluid or the pusher. The imaging device according to claim 1,
The first lens group includes at least one lens,
The second lens group includes at least one lens,
The lenses of the first lens group and the lenses of the second lens group are both aspherical lenses. The imaging device according to claim 1,
The variable focus lens is a film lens or a liquid lens. An electronic device,
It is characterized by including the imaging device according to any one of claims 1 to 8 .