JP2024073717A - Imaging device and electronic apparatus - Google Patents

Abstract

To provide an imaging device and an electronic apparatus.SOLUTION: An imaging device includes a first lens group with positive power, a second lens group with negative power, and an imaging element for imaging in the optical axis direction from the object side to the image side, further includes a variable focal lens located between the first lens group and second lens group, or on the most object side of the first lens group, and includes a housing part for movement-driving the first lens group in the optical axis direction. On the outside of the variable focal lens, there is a pusher that touches the housing part and movement-drives the variable focal lens and the first lens group. In addition, the following conditional expressions are satisfied. a<f1/f<b, ▵p/▵z>1, and 0.5<L/Lp<2, here f1: the focal length of the first lens group, f: the focal length of the imaging device, 0<a<1 and 1<b<2, ▵z: the movement amount of the first lens group in the optical axis direction, ▵p: the focus movement amount relative to the movement amount in the optical axis direction of the first lens group, L: the movement amount of the first lens group, and Lp: the push-in amount of the pusher.SELECTED DRAWING: Figure 1

Description

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

Normally, when focusing a lens, one or more lens focus groups are moved in the optical axis direction to focus from infinity to a close distance. In this case, multiple spaces must be secured for the focus groups to move in the optical axis direction, and the shorter the minimum shooting distance, the longer the stroke of the focus groups becomes, making them larger.

To solve this problem, there is a method of using a variable focus lens to focus from infinity to close distances without moving the focus group in the optical axis direction. Using this method solves the problem of large size caused by lens focusing. However, the optical power of a variable focus lens is generally inferior to that of a lens focus, and when focusing over a wide range from infinity to close distances, a single variable focus lens often does not have enough optical power. Furthermore, with a configuration that only has one focus group, it becomes difficult to maintain resolution performance (especially spherical aberration, field curvature, and chromatic aberration).

If multiple variable-focus lenses were used, the aberrations that occur when the object distance changes would reinforce each other, making it difficult to maintain high performance.

One solution is to combine a focus lens with a variable focus lens. In this case, the space required for movement in the optical axis direction is smaller than when multiple focus lenses are used, and the problem of interference between lenses is also solved; however, having two actuators, one for the focus lens and one for the variable focus lens, results in an increase in size.

At least one embodiment of the present invention provides an imaging device and electronic equipment to solve the problem of the imaging device becoming larger when a variable focus lens and a lens focus are used in combination.

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

As a first aspect, an embodiment of the present invention provides an imaging device including a first lens group having a positive power, a second lens group having a negative power, and an imaging element for forming an image, from the object side to the image side, in an optical axis direction. 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 is located closest to the object side of the first lens group. The first lens group has a housing part for driving and moving the first lens group in the optical axis direction. A pusher that comes into contact with the housing part is provided on the outside of the variable focus lens. The pusher drives and moves the variable focus lens and the first lens group. Here, the imaging device satisfies the following conditional expression.
a<f1/f<b
Δp/Δz>1
0.5<L/Lp<2
here,
f1: the focal length of the first lens group,
f: focal length of the imaging device,
0<a<1 and 1<b<2,
Δz: the amount of movement of the first lens group in the optical axis direction,
Δp: focus movement amount on the imaging surface relative to the movement amount Δz of the first lens group in the optical axis direction,
L: the amount of movement of the first lens group,
Lp: The amount of pressure applied by the pusher.

In a second aspect, an embodiment of the present invention provides an electronic device including the imaging device described above.

Compared to conventional technology, an imaging device according to an embodiment of the present invention has a variable focus lens that does not move in the optical axis direction installed inside the imaging device and is used in conjunction with a lens focus, and two types of lenses, the variable focus lens and the lens focus, are driven by a single pusher, making it possible to achieve a more compact structure for the imaging device.

FIG. 1 is a diagram showing a configuration of an imaging device according to an embodiment of the present invention. FIG. 2 is a diagram showing the configuration of the imaging device according to the embodiment of the present invention. FIG. 3 is a diagram showing the configuration of an imaging device according to an embodiment of the present invention. FIG. 4 is a diagram showing the configuration of the imaging device according to the embodiment of the present invention. FIG. 13 is a diagram showing a force applied to a pusher. FIG. 5 is a fifth diagram showing the configuration of an imaging device according to an embodiment of the present invention. FIG. 6 is a diagram showing the configuration of an imaging device according to an embodiment of the present invention. 5A to 5C are diagrams showing various aberrations of the imaging apparatus corresponding to the embodiment of FIG. 4 when the object distance is at infinity. 5A to 5C are diagrams showing various aberrations at a close distance of the imaging apparatus corresponding to the embodiment of FIG. 4. 8A to 8C are diagrams showing various aberrations of the imaging apparatus corresponding to the embodiment of FIG. 7 when the object distance is at infinity. 8A to 8C are diagrams showing various aberrations at a close distance of the imaging apparatus corresponding to the embodiment of FIG. 7 .

The technical means in the embodiments of the present application are described below clearly and completely with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, and are not all of them. All other embodiments that can be made by a person skilled in the art based on the embodiments of the present application without any creative work are all within the scope of protection of the present 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 intended to describe a particular order or priority. It should be understood that the data used in this manner may be appropriately interchanged so that the embodiments of this application can be practiced in an order other than that shown or described herein, and the objects distinguished by the terms "first", "second", etc. are generally of the same kind and the number of objects is not limited. For example, the first object may be one or more. Note that "and/or" in the specification and claims represents at least one of the connected objects. The character "/" generally indicates that the related objects before and after are in an "or" relationship.

To make the technical means related to the present invention easier to understand, the following describes the related concepts of the present invention.

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

As shown in Figures 1 to 7, an embodiment of the present invention provides 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 forming an image. The first lens group 1 has positive power, and the second lens group has negative power.

Here, the imaging element 3 is a light-sensitive element such as an image sensor.

Specifically, the first lens group 1 has positive power overall, and all or some of the lenses move in the optical axis direction when the object distance changes, and also have positive power.

The imaging device further includes a variable focus lens 4 arranged 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 is located on the most object side of the first lens group 1 as shown in FIG. 7. The first lens group 1 has a housing part 5 for driving the first lens group 1 to move in the optical axis direction. A pusher 6 that comes into contact with the housing part 5 is provided on the outside of the variable focus lens 4. The pusher 6 drives the variable focus lens 4 and the first lens group 1 to move.

Optionally, a voice coil motor VCM (Voice Coil Motor) is fitted inside 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, and the coil 7 is fixed inside the magnet 8 by two springs 9, one above the other. When electricity is applied to the coil 7, 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 upward, and the first lens group 1 inside the coil 7 moves together with it. When the power is turned off, the coil 7 returns due to the elasticity of the spring 9. In this way, an autofocus function is realized.

Here, the imaging device satisfies the following conditional expression.
a<f1/f<b
Δp/Δz>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: the amount of movement of the first lens group 1 in the optical axis direction,
Δp: focus movement amount on the imaging surface relative to movement amount Δz of the first lens group 1 in the optical axis direction,
L: the movement amount of the first lens group 1,
Lp: the amount of pressure applied by the pusher 6.

In one possible embodiment, the pusher 6 and the housing 5 are directly connected to each other or connected via a mechanism having a reduction ratio. For example, the mechanism having a reduction ratio is a gear. Note that, in order to easily adjust the amount of pushing of the pusher, the pusher 6 and the housing 5 are directly linked to each other, i.e., the reduction ratio is 1.

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

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

Refer to Figure 5, which shows the force applied to the pusher. The horizontal axis in the figure indicates the force applied to the pusher in g/mm2, and the vertical axis indicates the deviation/opening area in m/mm2. It is desirable to adjust this depending on the shape of the pusher and the viscosity of the material. Design it so that it is kept below the thrust of the actuator to be selected.

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

It is preferable that the imaging device further satisfies 0.4<Φ/Φ1<0.95 (where Φ is the maximum effective beam diameter of the variable focus lens 4, and Φ1 is the maximum effective beam diameter of the first lens group 1).

As shown in FIG. 4, when the variable focus lens 4 is positioned between the first lens group 1 and the second lens group 2, by giving positive power to the lens group on the object side of the variable focus lens 4, i.e., the first lens group 1, the light rays at the peripheral image height approach the light rays at the central image height, and the effective light diameter of the variable focus lens 4 can be made smaller than the effective light diameter of the first lens group 1. By reducing the effective light diameter of the variable focus lens 4, the size of the variable focus lens 4 can be reduced, resulting in reduced costs, faster response, and a more compact driving element.

Because the marginal rays are closer to the axial rays passing through the variable focus lens 4 than when the lens is disposed near the first lens group 1, it is possible to suppress the occurrence of curvature of field when the curvature of the variable focus lens 4 changes.

By placing 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.

If the upper limit of the conditional expression 0.5<f1/f<1.5 is exceeded, the positive power of the first lens group 1 becomes too weak, and the entire imaging device becomes large. On the other hand, if the lower limit of the conditional expression 0.5<f1/f<1.5 is not met, the positive power of the first lens group 1 becomes too strong, and the performance degradation of the imaging device when the object distance changes becomes significant. In addition, the precision required when assembling the lenses also increases, making manufacturing more difficult.

Furthermore, by satisfying the lower limit of the condition Δp/Δz>1, the minimum shooting distance can be shortened without unnecessarily extending the focus stroke.

If the upper limit of the conditional expression 0.4<Φ/Φ1<0.95 is exceeded, the diameter of the focus variable lens 4 is insufficiently small relative to the effective light diameter of the imaging device, resulting in increased costs and an increase in the size of the entire imaging device. On the other hand, if the lower limit of the conditional expression 0.4<Φ/Φ1<0.95 is not met, 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, resulting in an increase in the size of the entire imaging device.

Exceeding the upper limit of 0.5<L/Lp<2 will cause the stroke of the first lens group 1 to be extended, resulting in an increase in size. In addition, mechanisms with reduction ratios such as gears will become complicated. If the lower limit of 0.5<L/Lp<2 is exceeded, the variable-focus lens 4 will be sensitive to the movement of the first lens group 1, which will increase assembly precision during manufacturing and make it difficult to control the variable-focus lens.

In addition, by integrating the housing 5 that drives the first lens group 1 to move in the optical axis direction with the pusher 6 of the variable focus lens 4, it is expected that the size of the imaging device will be reduced by approximately 15% overall, and power consumption will be reduced by approximately 220 mW. In addition, the reduced number of parts will reduce costs, and the manufacturing process will eliminate the step of assembling the pusher, improving yields.

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 in 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 locating the variable focus lens 4 closest to the object side of the imaging device, manufacturing and assembly are made easier, and replacement of the variable focus lens 4 in the event of a defect is also simple, with the benefits of reducing the difficulty of assembling the lens and the manufacturing costs.

Below the lower limit of the conditional expression 0.6<f1/f<1.2, the positive power of the first lens group 1 becomes too strong, making it difficult to correct aberrations, and the required precision during lens assembly also increases, making it difficult to achieve high performance. On the other hand, above the upper limit of the conditional expression 0.6<f1/f<1.2, the focus stroke becomes long, making it difficult to miniaturize the entire imaging device.

In this embodiment, if the first lens group 1 and the second lens group 2 on the image side of the variable focus lens 4 are all used for focusing, the value of Δp/Δz will be 1. However, if the second lens group 2 located on the image side of the first lens group 1 has negative power, the focus stroke can be shortened by satisfying the condition Δp/Δz>1, which ultimately contributes to the miniaturization of the imaging device.

In addition, if the first lens group 1 and the second lens group 2 on the image side of the variable-focus lens 4 are all used for focusing, the direction of change in the image curvature that occurs in the variable-focus lens 4 when the object distance changes will be the same as the direction of change in the image curvature that occurs in the lens focus (first lens group 1, second lens group 2). This makes it difficult to achieve high performance, especially when the shooting distance is short, and makes it difficult to achieve a compact size, high performance, and a short minimum shooting distance.

Also, as in the above embodiment, the pusher 6 of the variable focus lens is pushed in as shown in Figure 2, so if the upper limit of the conditional formula 0.5<L/Lp<2 is exceeded, this causes the stroke of the first lens group 1 to be extended, resulting in an increase in size. Furthermore, unlike the above embodiment, 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, if the lower limit of the conditional formula 0.5<L/Lp<2 is exceeded, the variable focus lens 4 is sensitive to the movement of the first lens group 1, which increases the assembly precision during manufacturing and makes it difficult to control the variable focus lens.

The expected effect of integrating the pusher is a reduction in overall size of approximately 10% and a power saving effect of approximately 220 mW.

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

The aspheric formula used in the lens of the image pickup device according to the embodiment of the present invention is defined as follows.
Here, x is the amount of sag, y is the height from the optical axis, c is the paraxial curvature of the aspheric surface, which is the reciprocal of the radius of curvature of the aspheric surface, k is the conic constant of the aspheric surface, and A is the n-th aspheric coefficient.

Hereinafter, specific implementation parameters of the lens of the imaging device according to the embodiment of the present invention will be specifically described through four embodiments.
Example 1

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

In this embodiment 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 shows lens data corresponding to the lens structure in the imaging device in FIG. 4, Table 2 shows each aspheric coefficient corresponding to the lens in the imaging device in FIG. 4, and Table 3 shows the optical parameters of the imaging device shown in FIG. 4 when the object distance is infinity and at a close distance (30 mm). Table 4 shows the distance between the lens focus (first lens group) and the variable focus lens when the object distance is 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, the lenses in the imaging device adopt the size ranges in Example 1 above. In FIG. 8, FIG. 8A shows the curve of astigmatism when the object distance is infinite (in this drawing, the abscissa indicates the magnitude of astigmatism in mm, and the ordinate indicates the angle of view). FIG. 8B shows the curve of spherical aberration when the object distance is infinite (in this drawing, the abscissa indicates the spherical aberration in mm, and the ordinate indicates the aperture value). FIG. 8C shows the curve of distortion aberration when the object distance is infinite (in this drawing, the abscissa indicates the magnitude of distortion in %, and the ordinate indicates the angle of view).

In FIG. 9, FIG. 9A shows the curve of astigmatism when the object distance is close (in this drawing, the abscissa indicates the magnitude of astigmatism in mm, and the ordinate indicates the angle of view). FIG. 9B shows the curve of spherical aberration when the object distance is close (in this drawing, the abscissa indicates spherical aberration in mm, and the ordinate indicates the aperture value). FIG. 9C shows the curve of distortion aberration when the object distance is close (in this drawing, the abscissa indicates the magnitude of distortion in %, and the ordinate indicates the angle of view).

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

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

Here, the lenses in the imaging device adopt the size range in Example 2 above. In FIG. 10, FIG. 10A shows the curve of astigmatism when the object distance is infinite (in this drawing, the abscissa indicates the magnitude of astigmatism in mm, and the ordinate indicates the angle of view). FIG. 10B shows the curve of spherical aberration when the object distance is infinite (in this drawing, the abscissa indicates the spherical aberration in mm, and the ordinate indicates the aperture value). FIG. 10C shows the curve of distortion aberration when the object distance is infinite (in this drawing, the abscissa indicates the magnitude of distortion in %, and the ordinate indicates the angle of view).

In FIG. 11, FIG. 11A shows the curve of astigmatism when the object distance is close (in this drawing, the abscissa indicates the magnitude of astigmatism in mm, and the ordinate indicates the angle of view). FIG. 11B shows the curve of spherical aberration when the object distance is close (in this drawing, the abscissa indicates spherical aberration in mm, and the ordinate indicates the aperture value). FIG. 11C shows the curve of distortion aberration when the object distance is close (in this drawing, the abscissa indicates the magnitude of distortion in %, and the ordinate indicates the angle of view).

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

In this invention, assuming the combined use of a variable focus lens and a lens focus, and integrating the lens focus and the pusher that drives the variable focus lens, it is possible to achieve a shorter minimum shooting distance, a smaller size, and higher performance by satisfying the conditional expressions for each lens group described above.

Furthermore, an embodiment of the present invention further provides an electronic device including the imaging device described above.

The imaging lens described above is also used in imaging devices for portable information devices such as so-called smart phones, so-called feature phones, and tablet devices.

The electronic device in the embodiment of the present invention may be a mobile electronic device or a non-mobile electronic device. For example, the mobile electronic device may be a mobile phone, a tablet PC, a notebook computer, a palm computer, an in-vehicle electronic device, a wearable device, an ultra-mobile personal computer (UMPC), a netbook, or a personal digital assistant (PDA), and the non-mobile electronic device may be a server, a network attached storage (NAS), a personal computer (PC), a television (TV), an ATM, or a self-service machine, but is not limited to these in the embodiment of the present invention.

Although the present invention has been described above with reference to 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 implement without departing from the spirit of the present invention and the scope of the claims are all included in the scope of protection of the present invention.

Claims (11)

1. An imaging device, comprising:
a first lens group having a positive power, a second lens group having a negative power, and an image pickup device for forming an image, the first lens group being arranged in an optical axis direction from the object side to the image side;
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 is located closest to the object side of the first lens group;
the first lens group has a housing portion for driving the first lens group to move in an optical axis direction;
a pusher that comes into contact with the housing is provided on the outside of the variable focus lens;
the pusher drives and moves the variable focus lens and the first lens group;
The imaging device includes:
a<f1/f<b
Δp/Δz>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: the amount of movement of the first lens group in the optical axis direction,
Δp: focus movement amount on the imaging surface relative to the movement amount Δz of the first lens group in the optical axis direction,
L: the amount of movement of the first lens group,
Lp: the pushing amount of the pusher) is satisfied. 2. 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 in that 0.5<f1/f<1.5 is satisfied. 3. The imaging device according to claim 2,
The maximum effective beam diameter of the variable focus lens is smaller than the maximum effective beam diameter of the first lens group. 4. The imaging device according to claim 3,
0.4<Φ/Φ1<0.95
(Φ: maximum effective beam diameter of the variable focus lens,
Φ1: maximum effective light beam diameter of the first lens group). 2. The imaging device according to claim 1,
When the variable-focus lens is located closest to the object side in the first lens group,
It is characterized in that 0.6<f1/f<1.2 is satisfied. 2. The imaging device according to claim 1,
The pusher and the housing are connected directly or via a mechanism having a reduction ratio. 2. The imaging device according to claim 1,
The variable focus lens is characterized in that an optical fluid is sealed therein. 8. The imaging device according to claim 7,
The pushing amount of the pusher is determined by the area of the optical fluid or the pusher. 2. 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 in the first lens group and the lenses in the second lens group are both aspheric lenses. 2. The imaging device according to claim 1,
The variable focus lens is characterized in that it is a membrane lens or a liquid lens. An electronic device,
The present invention is characterized by including an imaging device according to any one of claims 1 to 9.