CN116774394A - Optical system, imaging device, vehicle-mounted system and mobile device - Google Patents

Abstract

The present disclosure relates to an optical system, an imaging device, an in-vehicle system, and a mobile device. The optical system includes a negative lens and a positive lens adjacent to each other, wherein the following inequality is satisfied: DAB is 0.00.ltoreq.DAB is 1.00 and RA/RB is 0.80.ltoreq.RA/RB is 1.20, wherein DAB [ mm ] represents the distance between the negative lens and the positive lens on the optical axis, and RA and RB represent the radii of curvature of the lens surfaces of the negative lens and the positive lens, respectively, facing each other, and wherein a specific inequality is satisfied.

Description

Optical system, imaging device, vehicle-mounted system and mobile device

Technical Field

The present invention relates to an optical system and is applicable to imaging apparatuses such as digital still cameras, digital video cameras, in-vehicle cameras, mobile phone cameras, monitoring cameras, wearable cameras, and medical cameras.

Background

As an optical system used in an imaging device, an optical system having high optical performance irrespective of ambient temperature is required. Japanese patent application laid-open No.2021-71502 discusses an optical system that can control a focal position change due to an environmental temperature change using a pair of positive and negative lenses having a large difference in refractive index and abbe number.

However, in the optical system discussed in japanese patent application laid-open No.2021-71502, a pair of positive and negative lenses having a large difference in refractive index and abbe number needs to be employed so that the degree of freedom in selection of materials of the respective lenses is not high. Therefore, depending on the specifications of the optical system, it may be difficult to achieve both control of the focus position variation due to the change in the ambient temperature and correction of various aberrations.

Disclosure of Invention

According to an aspect of the present invention, an optical system includes a negative lens and a positive lens adjacent to each other, wherein the following inequality is satisfied:

DAB 0.00.ltoreq.DAB 1.00, and

0.80≤RA/RB≤1.20，

wherein DAB [ mm ] represents the distance between the negative lens and the positive lens on the optical axis, and RA and RB represent the radii of curvature of the facing lens surfaces of the negative lens and the positive lens, respectively, and wherein the following inequality is satisfied:

0.00≤|NA-NB|≤0.20，

0.00 < v > A-v > B < 20.00, and

4.2≤|dnA/dt-dnB/dt|,

wherein NA and NB denote refractive indices of the negative and positive lenses, respectively, with respect to d-line, vA and vB denote Abbe numbers of the negative and positive lenses, respectively, with respect to d-line, and dnA/dt [10 ] ^-6 /℃]And dnB/dt [10 ] ^- 6/℃]The temperature coefficients of the refractive index of the negative and positive lenses with respect to the d-line at 20 ℃ to 40 ℃ are represented, respectively, and either dnA/dt or dnB/dt has a negative sign.

Other features of the present invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings.

Drawings

Fig. 1 is a schematic diagram of the main part of an optical system according to example 1.

Fig. 2 is a Modulation Transfer Function (MTF) diagram of an optical system according to example 1.

Fig. 3 is a schematic diagram of a main part of an optical system according to example 2.

Fig. 4 is an MTF diagram of an optical system according to example 2.

Fig. 5 is a schematic diagram of a main part of an optical system according to example 3.

Fig. 6 is an MTF diagram of an optical system according to example 3.

Fig. 7 is a schematic diagram of a main part of an optical system according to example 4.

Fig. 8 is an MTF diagram of an optical system according to example 4.

Fig. 9 is a schematic diagram of a main part of an optical system according to example 5.

Fig. 10 is an MTF diagram of an optical system according to example 5.

Fig. 11 is a schematic diagram of a main part of an optical system according to example 6.

Fig. 12 is an MTF diagram of an optical system according to example 6.

Fig. 13 is a schematic diagram of a main part of an optical system according to example 7.

Fig. 14 is an MTF diagram of an optical system according to example 7.

Fig. 15 is a schematic diagram of a main part of an optical system according to example 8.

Fig. 16 is an MTF diagram of an optical system according to example 8.

Fig. 17 is a schematic diagram of a main part of an optical system according to example 9.

Fig. 18 is an MTF diagram of an optical system according to example 9.

Fig. 19 is a schematic diagram of a main part of an optical system according to reference example 1.

Fig. 20 is an MTF diagram of an optical system according to reference example 1.

Fig. 21 is a schematic diagram of a main part of an optical system according to reference example 2.

Fig. 22 is an MTF diagram of an optical system according to reference example 2.

Fig. 23 is a schematic diagram of an imaging apparatus according to an exemplary embodiment.

Fig. 24 is a functional block diagram of an in-vehicle system according to an exemplary embodiment.

Fig. 25 is a schematic diagram of a vehicle according to an exemplary embodiment.

Fig. 26 is a flowchart illustrating an operation example of the in-vehicle system according to the exemplary embodiment.

Detailed Description

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. For convenience, the drawings are sometimes drawn to scale different from the actual scale. In the drawings, similar components are assigned the same reference numerals, and redundant description will be omitted.

The optical system according to the present exemplary embodiment includes a negative lens and a positive lens adjacent to each other, an interval between the negative lens and the positive lens on the optical axis satisfies the following inequality (1), and radii of curvature of facing (prescription) lens surfaces of the negative lens and the positive lens satisfy the following inequality (2). Further, the negative lens and the positive lens are made of materials satisfying the following inequalities (3) to (5). Employing such a configuration enables realization of an optical system that can control a change in focal position due to a change in ambient temperature.

The optical system according to the present exemplary embodiment can produce the advantageous effects of the present invention as long as at least the above-described configuration is satisfied. For example, the optical system may have a configuration including a plurality of positive lenses, or a configuration including a plurality of negative lenses. The order of the negative lens and the positive lens satisfying the inequality may be appropriately selected depending on the specifications of the optical system. An optical element such as a filter or a cover glass that does not contribute to image formation of the optical system may be arranged at a position closer to the image plane than a lens (last lens) arranged closest to the image plane among lenses constituting the optical system.

Hereinafter, an example of the optical system according to the present exemplary embodiment will be described in detail.

Example 1

Example 1 of the present invention will be described below. Fig. 1 is a schematic view of a main part in a cross section including an optical axis of an optical system according to example 1 of the present invention. In fig. 1, the left side corresponds to the object side (front side), and the right side corresponds to the image side (rear side). The optical system according to this example is an image forming optical system that forms an image of an object (object) (not shown) on an image plane IM1 by converging light from the object. In other words, the optical system according to this example has a positive refractive power in the entire system. In the case where the optical system according to this example is applied to an imaging device, an imaging plane (light receiving surface) of an image sensor (light receiving element) is arranged at the position of the imaging plane IM 1.

The optical system according to this example is an optical system having a focal length of 11.10mm and a half field angle of 60 °. The optical system according to this example includes a negative lens L11, a negative lens L12, a first cemented lens AT1, an aperture stop S1, a positive lens L15, a cemented lens L10, a cemented lens L20, and a positive lens L110, which are arranged in order from the object side to the image side. The first cemented lens AT1 is composed of a negative lens L13 and a positive lens L14 arranged in order from the object side to the image side, and the cemented lens L10 is composed of a positive lens L16 and a negative lens L17 arranged in order from the object side to the image side. The cemented lens L20 is composed of a positive lens L18 and a negative lens L19 arranged in order from the object side to the image side. The positive lens and the negative lens in the respective cemented lenses are cemented with each other by a cementing member such as an adhesive. An Infrared (IR) cut filter F1 serving as a filter and a cover glass CG1 are arranged on the image side of a positive lens L110 as the last lens.

As described above, an optical system to be used in an imaging device will be able to control a focus position change due to an ambient temperature change. It is known that the following equation (a) is satisfied:

Δf＝β×ΔT×f(A),

where, for one lens (single lens) in the optical system, Δf represents the amount of change in focal length with the change in ambient temperature, β represents a coefficient, Δt represents the amount of change in ambient temperature, and f represents the focal length set before the change in ambient temperature.

The coefficient β in equation (a) is represented by the following equation (B):

β＝α-dndt/(N-1)(B),

where, for a single lens, N represents the refractive index for the d-line (wavelength 587.56 nm), α represents the linear expansion coefficient, and dndt represents the temperature coefficient of the refractive index.

According to equation (a), in the case where the ambient temperature increases, if the coefficient β has a positive value, the focal length of the positive lens varies positively, while the focal length of the negative lens varies negatively. In the optical system discussed in the above japanese patent application laid-open No.2021-71502, a pair of negative and positive lenses whose respective coefficients β have positive values are employed so that the change in focal position due to the change in ambient temperature is controlled.

However, the material having a positive value of the coefficient β is limited to a material having a negative value of the temperature coefficient dndt of the refractive index, and a material having a very large value of the linear expansion coefficient α. Therefore, materials with positive values of the coefficient β are fewer in number than materials with negative values of the coefficient β. Many materials with positive coefficients beta are known to have anomalous dispersion characteristics and low refractive indices. For this reason, in the case of using a pair of negative and positive lenses whose coefficients β have positive values to control the change in focal position due to the change in ambient temperature, it may be difficult to correct various aberrations depending on the materials of the respective lenses. That is, it may be difficult to achieve both control of focus position variation due to environmental temperature change (temperature compensation) and correction of various aberrations.

In view of the foregoing, in this example, the relative positions and shapes of the negative lens and the positive lens adjacent to each other, and the conditions of the materials are appropriately set. This enables control of the focal position variation due to the change in ambient temperature, regardless of the sign of the value of the coefficient β of each lens. Therefore, the degree of freedom in selection of materials for the respective lenses can be enhanced. This facilitates both temperature compensation and correction of various aberrations in the optical system. Hereinafter, features of the optical system according to this example will be described in detail.

First, the optical system according to this example includes a negative lens L13 and a positive lens L14 as a pair of negative and positive lenses for performing temperature compensation. The optical system according to this example satisfies the following inequalities (1) and (2):

DAB 0.00.ltoreq.DAB 1.00 (1), and

0.80≤RA/RB≤1.20 (2)，

where DAB [ mm ] denotes the distance on the optical axis between the negative lens L13 and the positive lens L14, and RA and RB denote the radii of curvature of the lens surfaces facing the negative lens L13 and the positive lens L14, respectively. Each of these inequalities is assumed to be a value at room temperature (25 ℃).

By satisfying the inequality (1), the negative lens L13 and the positive lens L14 can be arranged close to each other, thereby facilitating realization of both temperature compensation and correction of various aberrations. In the case where inequality (1) is not satisfied, the interval between the negative lens L13 and the positive lens L14 becomes too large, which makes it difficult to achieve both temperature compensation and correction of various aberrations even if the following inequalities (3) to (5) are satisfied. In this example, dab=0.00 is obtained since the negative lens L13 and the positive lens L14 are glued to each other.

The inequality (2) is satisfied such that the shapes of the facing lens surfaces of the negative lens L13 and the positive lens L14 are substantially the same. With this configuration, even in the case where the negative lens L13 and the positive lens L14 are not cemented with each other, the pair of the negative lens L13 and the positive lens L14 can have a function equivalent to that of the cemented lens. In the case where inequality (2) is not satisfied, the difference in radius of curvature between the facing lens surfaces of the negative lens L13 and the positive lens L14 becomes too large. This makes it difficult to dispose the negative lens L13 and the positive lens L14 close to each other in such a manner that inequality (1) is satisfied. Therefore, it becomes difficult to achieve both temperature compensation and correction of various aberrations. In this example, since the negative lens L13 and the positive lens L14 are cemented with each other, RA/rb=1.00 is obtained.

The optical system according to this example satisfies the following inequalities (3) to (5):

0.00≤ |NA - NB| ≤0.20 (3)，

0.00 < v > A-v > B < 20.00 (4), and

4.20≤ |dnA/dt - dnB/dt| (5)，

wherein NA and NB are dividedRefractive indices of the negative lens L13 and the positive lens L14 with respect to the d-line are shown, νA and νB represent Abbe numbers of the negative lens L13 and the positive lens L14 with respect to the d-line, respectively, and dnA/dt [10 ] ^-6 /℃]And dnB/dt [10 ] ^-6 /℃]The temperature coefficients of refractive indexes of the negative lens L13 and the positive lens L14 with respect to the d-line at 20 ℃ to 40 ℃, respectively. Each of these inequalities is assumed to be a value at room temperature (25 ℃).

Inequalities (3) to (5) indicate that the negative lens L13 and the positive lens L14 are made of mutually different materials, the refractive index difference and the dispersion difference between the materials are small, and the difference in temperature coefficient of refractive index is large. A general cemented lens obtains a function of correcting chromatic aberration and curvature of field by being composed of a negative lens and a positive lens having a large refractive index difference and a large dispersion difference. In contrast thereto, in this example, the refractive index difference and the dispersion difference between the negative lens L13 and the positive lens L14 are reduced to satisfy the inequalities (3) and (4), so that the first cemented lens AT1 has a function equivalent to that of a single lens AT room temperature. This reduces the influence of the first cemented lens AT1 on the aberration variation of the optical system when the ambient temperature changes from room temperature.

The difference in temperature coefficient of refractive index between the negative lens L13 and the positive lens L14 is increased to satisfy inequality (5), so that the first cemented lens AT1 functions as a cemented lens for temperature compensation in the case where the ambient temperature is changed from room temperature. More specifically, in the case where the ambient temperature is changed from room temperature, the refraction angle of light on the bonding surface of the negative lens L13 and the positive lens L14 becomes larger than that at room temperature. By utilizing this, it is possible to control the convergence (divergence) of light rays and control the change in focal position using the first cemented lens AT 1.

In the case where inequalities (3) and (4) are not satisfied, the refractive index difference and the chromatic dispersion difference between the negative lens L13 and the positive lens L14 become too large, and it becomes difficult to control aberration variation of the optical system due to a change in ambient temperature from room temperature. In the case where inequality (5) is not satisfied, the difference in temperature coefficient of refractive index between the negative lens L13 and the positive lens L14 becomes too small, and it becomes difficult to control the change in focal position of the optical system due to the change in ambient temperature from room temperature.

In the optical system according to this example, a material having a negative sign in the temperature coefficient of refractive index is used as the material of either one of the positive lens or the negative lens. I.e. either nA/dt or dnB/dt is negative in sign. This configuration increases the difference in coefficient β between the positive lens and the negative lens, which enhances the effect of controlling the change in focal position due to the change in ambient temperature while satisfying the above-described inequalities (1) to (5).

In this way, the optical system according to this example is characterized in that inequalities (1) to (5) are simultaneously satisfied. This makes it possible to appropriately set the relative positions and shapes of the negative lens L13 and the positive lens L14 and the conditions of the materials so that the focal position variation due to the environmental temperature change is controlled regardless of the sign of the value of the coefficient β of each lens. Further, it is preferable to satisfy the following inequalities (1 a) to (5 a), and it is more preferable to satisfy the inequalities (1 b) to (5 b).

0.00≤DAB≤0.80(1a)

0.85≤RA/RB≤1.15(2a)

0.00≤|NA-NB|≤0.17(3a)

0.00≤|νA-νB|≤17.2(4a)

4.5≤|dnA/dt-dnB/dt|≤12.1(5a)

0.00≤DAB≤0.60(1b)

0.90≤RA/RB≤1.10(2b)

0.00≤|NA-NB|≤0.14(3b)

0.00≤|νA-νB|≤14.6(4b)

4.5≤|dnA/dt-dnB/dt|≤10.23(5b)

The negative lens L13 and the positive lens L14 only need to be adjacent to each other, and may be separated from each other as needed. Even in the case where the negative lens L13 and the positive lens L14 are separated from each other, by reducing the distance and shape difference between the negative lens L13 and the positive lens L14 to satisfy the inequalities (1) and (2), an effect similar to that produced in the case where the negative lens L13 and the positive lens L14 are cemented with each other can be produced. In other words, if the first cemented lens AT1 is not present in the optical system, but includes a pair of negative lenses L13 and positive lenses L14 (such a pair is referred to as a lens unit) that satisfy the inequalities (1) to (5), a similar effect can be produced. The order of arrangement of the negative lenses L13 and the positive lenses L14 or their arrangement in the optical system may be changed as needed.

The optical system according to this example desirably satisfies the following inequality (6):

0.00 < |βA - βB| (6)，

wherein alpha A10 ^-6 /℃]And alpha B10 ^-6 /℃]The linear expansion coefficients of the negative lens L13 and the positive lens L14 are shown, respectively. From the above equation (B), βa=αa-dnA/dt/(NA-1) and βb=αb-dnB/dt/(NB-1) are obtained. The linear expansion coefficient in this inequality is the average linear expansion coefficient at-30℃to 70 ℃.

Satisfying inequality (6) brings about a difference between the values of the coefficients β of the negative lens L13 and the positive lens L14. This facilitates control of the focal position change due to the change of the ambient temperature from room temperature. In the case where inequality (6) is not satisfied, the difference in coefficient β between the negative lens L13 and the positive lens L14 becomes too small, so that it is difficult to provide the negative lens L13 and the positive lens L14 with the function of temperature compensation, which is undesirable.

A larger value of inequality (6) is desirable for temperature compensation, but if the value of inequality (6) is too large, it may become difficult to purchase (procure) the materials of the negative lens L13 and the positive lens L14. Accordingly, in consideration of the purchasing difficulty of various materials, it is desirable to sequentially satisfy the following inequalities (6 a) to (6 c):

2.9<|βA-βB|<21.0 (6a)，

4.1< |βa- βb| <18.2 (6B), and

5.3<|βA-βB|<15.4 (6c)。

in order to increase the control amount of the focal position change due to the environmental temperature change, the maximum value of βa or βb is desirably greater than or equal to 8.0. This facilitates increasing the difference in coefficient β between the positive lens and the negative lens.

In the case where the negative lens L13 and the positive lens L14 are cemented with each other as in this example, the optical system desirably satisfies the following inequality (7):

0.10×10 ^-3 < |Dk/R| < 1.00 (7)

where R represents the radius of curvature of the cemented surface of each lens and Dk represents the effective diameter. In this inequality, the radius of curvature R is equal to the above-described radii of curvature RA and RB (r=ra=rb). In this inequality, the effective diameter is the radius of the effective area on the glued surface through which the effective light rays contributing to image formation pass.

Satisfying inequality (7) facilitates processing and bonding of facing lens surfaces of the negative lens L13 and the positive lens L14, thereby facilitating manufacturing of the first bonding lens AT 1. In the case where inequality (7) is not satisfied, it becomes difficult to process and glue the facing lens surfaces of the negative lens L13 and the positive lens L14, which is undesirable. Further, it is desirable to satisfy the following inequality (7 a), and it is more desirable to satisfy the inequality (7 b):

0.01<|Dk/R|<1.00(7a)

0.10<|Dk/R|<1.00(7b)。

In the first cemented lens AT1, for the cemented lens L10 (positive lens L16, negative lens L17) and the cemented lens L20 (positive lens L18, negative lens L19), all of the facing lens surfaces (cemented surfaces) of the negative lens and the positive lens desirably have a convex shape protruding toward the object side, or are planar. With this configuration, aberration correction and miniaturization of the entire system become easier. The negative lens L13 and the positive lens L14 in the first cemented lens AT1 desirably have a convex shape protruding toward the object side, or are planar. With this configuration, temperature compensation and miniaturization of the entire system become easier. A similar configuration applies to the case where the negative lens L13 and the positive lens L14 in the first cemented lens AT1 are separated from each other.

Fig. 2 is a graph illustrating a Modulation Transfer Function (MTF) curve of an optical system according to this example. Fig. 2 illustrates three modes corresponding to a case where the ambient temperature of the environment in which the optical system is disposed is room temperature (25 ℃), a case where the ambient temperature is low (-40 ℃) and a case where the ambient temperature is high (85 ℃). In fig. 2, the horizontal axis indicates spatial frequency [ period/mm ], and the vertical axis indicates MTF value (contrast value). Fig. 2 illustrates a curve indicating the diffraction limit, an MTF curve of an on-axis ray (ray having a center angle of view of 0 °) reaching an on-axis image height, and an MTF curve of an outermost off-axis ray (ray having a half angle of view of 60 °) reaching an outermost off-axis image height.

The optical system according to this example includes a pair of negative lenses L13 and positive lenses L14 that satisfy the above-described inequality. More specifically, the optical system includes a first cemented lens AT1, the first cemented lens AT1 being composed of a negative lens L13 and a positive lens L14, wherein the negative lens L13 is composed of S-LAH60V manufactured by Ohara Inc, and the positive lens L14 is composed of S-LAH60MQ manufactured by Ohara Inc. As shown in fig. 2, at room temperature (25 ℃) the minimum value of the MTF value at a spatial frequency of 83 cycles/mm (corresponding to half the nyquist frequency (Nyquist frequency)) is about 68%, achieving good image forming performance. The minimum value of the MTF value at a spatial frequency of 68 cycles/mm at low temperature (-40 ℃) and high temperature (85 ℃) is about 68%. In other words, it can be seen that the temperature compensation of the first cemented lens AT maintains good image forming performance even if the ambient temperature changes.

Example 2

Example 2 of the present invention will be described. Fig. 3 is a schematic diagram of a main portion in a section including an optical axis of the optical system according to example 2. A description of components in the optical system according to this example that are equivalent to those in the optical system according to example 1 described above will be omitted.

The optical system according to this example is an optical system having a focal length of 16.15mm and a half field angle of 17.5 °. The optical system according to this example includes an aperture stop S2, a first positive lens L21, a first negative lens L22, a first cemented lens L10, a second cemented lens L20, a second positive lens L27, a third cemented lens AT2, and a second negative lens L210, which are arranged in order from the object side to the image side. The first cemented lens L10 is composed of a negative lens L23 and a positive lens L24 arranged in order from the object side to the image side, and the second cemented lens L20 is composed of a negative lens L25 and a positive lens L26 arranged in order from the object side to the image side. The third cemented lens AT2 is composed of a negative lens L28 having a convex shape protruding toward the object side and a positive lens L29 cemented to the surface of the negative lens L28 on the image side. The cover glass CG2 is arranged between the second negative lens L210 as the last lens and the image plane IM 2.

The optical system according to this example adopts a configuration (front stop type) in which an aperture stop S2 that determines an F-number (Fno) by restricting light from an object is arranged at a position closest to the object. This configuration allows light confined by the aperture stop S2 to enter all lenses, thus reducing the size of the lenses, which results in a reduction in the size of the entire optical system. In this example, the negative lens L28 and the positive lens L29 in the third cemented lens AT2 satisfy the above-described inequality. With this configuration, the third cemented lens AT2 functions as a cemented lens for temperature compensation, thereby realizing both control of focal position variation due to environmental temperature change and correction of various aberrations.

In this example, the shape and arrangement of the lenses are designed in such a way that high optical performance is obtained with the front stop type optical system employed. More specifically, the optical system according to this example adopts a configuration in which the first cemented lens L10 and the second cemented lens L20 are sequentially arranged on the image side of the aperture stop S2 in order from the object side to the image side. Further, each cemented lens includes a negative lens having a concave surface on the object side and a positive lens cemented to the surface of the negative lens on the image side. More specifically, the first cemented lens L10 includes a negative lens L23 having a concave surface on the object side and a positive lens L24 cemented to the surface of the negative lens L23 on the image side. The second cemented lens L20 includes a negative lens L25 having a concave surface on the object side and a positive lens L26 cemented to the surface of the negative lens L25 on the image side.

In this way, two cemented lenses each having a concave surface on the object side are arranged in succession, so that the arrangement of lenses on the image side of the aperture stop S2 is appropriately set in this example. This makes it possible to appropriately correct various aberrations with the lens on the image side of the aperture stop S2 when the aperture stop S2 is arranged at the position closest to the object. It is further desirable that the first positive lens having a convex shape protruding toward the object side and the first negative lens having a convex shape protruding toward the object side are arranged on the object sides of the two cemented lenses. With these configurations, both miniaturization and high optical performance of the entire system can be achieved without using a large number of aspherical surfaces.

Fig. 4 is a diagram illustrating an MTF curve of the optical system according to this example. As shown in fig. 4, at room temperature (25 ℃) the minimum value of the MTF value at a spatial frequency of 68 cycles/mm (corresponding to half the nyquist frequency) is about 53%, and thus good image forming performance is achieved. The minimum values of the MTF values at a spatial frequency of 68 cycles/mm at low temperature (-40 ℃) and high temperature (85 ℃) were about 54% and about 51%, respectively. In other words, it can be seen that by the temperature compensation performed by the third cemented lens AT2, good image forming performance can be maintained even in the case where the ambient temperature changes.

Example 3

Example 3 of the present invention will be described below. Fig. 5 is a schematic view of a main part in a cross section including an optical axis of the optical system according to example 3. A description of components in the optical system according to this example that are equivalent to those in the optical system according to example 1 described above will be omitted.

The optical system according to this example is an optical system having a focal length of 8.70mm and a half field angle of 60 °. The optical system according to this example includes a negative lens L31, a negative lens L32, a cemented lens AT3, an aperture stop S3, a positive lens L35, a cemented lens L10, a cemented lens L20, and a negative lens L310, which are arranged in order from the object side to the image side. The cemented lens AT3 is composed of a negative lens L33 and a positive lens L34 arranged in order from the object side to the image side, and the cemented lens L10 is composed of a positive lens L36 and a negative lens L37 arranged in order from the object side to the image side. The cemented lens L20 is composed of a positive lens L38 and a negative lens L39 arranged in order from the object side to the image side. The positive lens and the negative lens in the respective cemented lenses are cemented with each other by a cementing member such as an adhesive. An infrared cut filter F3 serving as a filter and a cover glass CG3 are arranged on the image side of the second negative lens L310 serving as the last lens. In this example, the cemented lens AT3 functions as a cemented lens for temperature compensation, thereby realizing both control of focal position variation due to environmental temperature change and correction of various aberrations.

Fig. 6 is a diagram illustrating an MTF curve of the optical system according to this example. As shown in fig. 6, at room temperature (25 ℃) the minimum value of the MTF value at a spatial frequency of 83 cycles/mm (corresponding to half the nyquist frequency) is about 63%, and thus good image forming performance is achieved. The minimum values of the MTF values at a spatial frequency of 83 cycles/mm at low temperature (-40 ℃) and high temperature (85 ℃) were about 65% and about 66%, respectively. In other words, it can be seen that by the temperature compensation performed by the cemented lens AT3, good image forming performance can be maintained even in the case where the ambient temperature changes.

Example 4

Example 4 of the present invention will be described. Fig. 7 is a schematic diagram of a main portion in a section including an optical axis of the optical system according to example 4. A description of components in the optical system according to the present example that are equivalent to those in the optical system according to example 1 described above will be omitted.

The optical system according to this example is an optical system having a focal length of 8.69mm and a half field angle of 60 °. The optical system according to this example includes a negative lens L41, a negative lens L42, a cemented lens AT4, an aperture stop S4, a positive lens L45, a cemented lens L10, a cemented lens L20, and a negative lens L410, which are arranged in order from the object side to the image side. The cemented lens AT4 is composed of a negative lens L43 and a positive lens L44 arranged in order from the object side to the image side, and the cemented lens L10 is composed of a positive lens L46 and a negative lens L47 arranged in order from the object side to the image side. The cemented lens L20 is composed of a positive lens L48 and a positive lens L49 arranged in order from the object side to the image side. The positive lens and the negative lens in the respective cemented lenses are cemented with each other by a cementing member such as an adhesive. An infrared cut filter F4 serving as a filter and a cover glass CG4 are arranged on the image side of the second negative lens L410 as the last lens. In this example, the cemented lens AT4 functions as a cemented lens for temperature compensation, thereby realizing both control of focal position variation due to environmental temperature change and correction of various aberrations.

Fig. 8 is a diagram illustrating an MTF curve of an optical system according to this example. As shown in fig. 8, at room temperature (25 ℃) the minimum value of the MTF value at a spatial frequency of 83 cycles/mm (corresponding to half the nyquist frequency) is about 69%, and thus good image forming performance is achieved. The minimum values of the MTF values at a spatial frequency of 83 cycles/mm at low temperature (-40 ℃) and high temperature (85 ℃) were about 57% and about 66%, respectively. In other words, it can be seen that by the temperature compensation performed by the cemented lens AT4, good image forming performance can be maintained even in the case where the ambient temperature changes.

Example 5

Example 5 of the present invention will be described. The optical system according to the present example has a focal length of 9.00mm and a half field angle of 60 °. Fig. 9 is a schematic diagram of a main portion in a section including an optical axis of the optical system according to example 5. A description of components in the optical system according to the present example that are equivalent to those in the optical system according to example 1 described above will be omitted.

The optical system according to this example includes a negative lens L51, a negative lens L52, a cemented lens AT5, an aperture stop S5, a positive lens L55, a cemented lens L10, a cemented lens L20, and a negative lens L510, which are arranged in order from the object side to the image side. The cemented lens AT5 is composed of a negative lens L53 and a positive lens L54 arranged in order from the object side to the image side, and the cemented lens L10 is composed of a positive lens L56 and a negative lens L57 arranged in order from the object side to the image side. The cemented lens L20 is composed of a positive lens L58 and a negative lens L59 arranged in order from the object side to the image side. The positive lens and the negative lens in the respective cemented lenses are cemented with each other by a cementing member such as an adhesive. An infrared cut filter F5 serving as a filter and a cover glass CG5 are arranged on the image side of the second negative lens L510 as the last lens. In this example, the cemented lens AT5 functions as a cemented lens for temperature compensation, thereby achieving both suppression of focus position variation due to environmental temperature change and correction of various aberrations.

Fig. 10 is a diagram illustrating an MTF curve of an optical system according to this example. As shown in fig. 10, at room temperature (25 ℃) the minimum value of the MTF value at a spatial frequency of 83 cycles/mm (corresponding to half the nyquist frequency) is about 69%, and thus good image forming performance is achieved. The minimum values of the MTF values at a spatial frequency of 83 cycles/mm at low temperature (-40 ℃) and high temperature (85 ℃) were about 60% and about 68%, respectively. In other words, it can be seen that by the temperature compensation performed by the cemented lens AT5, good image forming performance can be maintained even in the case where the ambient temperature changes.

Example 6

Example 6 of the present invention will be described. Fig. 11 is a schematic diagram of a main portion in a section including an optical axis of an optical system according to example 6. A description of components in the optical system according to the present example that are equivalent to those in the optical system according to example 1 described above will be omitted.

The optical system according to this example has a focal length of 8.25mm and a half field angle of 60 °. The optical system according to this example includes a negative lens L61, a negative lens L62, a cemented lens AT6, an aperture stop S6, a positive lens L65, a cemented lens L10, a cemented lens L20, and a negative lens L610, which are arranged in order from the object side to the image side. The cemented lens AT6 is composed of a negative lens L63 and a positive lens L64 arranged in order from the object side to the image side, and the cemented lens L10 is composed of a positive lens L66 and a negative lens L67 arranged in order from the object side to the image side. The cemented lens L20 is composed of a positive lens L68 and a negative lens L69 arranged in order from the object side to the image side. The positive lens and the negative lens in the respective cemented lenses are cemented with each other by a cementing member such as an adhesive. An infrared cut filter F6 serving as a filter and a cover glass CG6 are arranged on the image side of the second negative lens L610 as the last lens. In this example, the cemented lens AT6 functions as a cemented lens for temperature compensation, thereby realizing both control of focal position variation due to environmental temperature change and correction of various aberrations.

Fig. 12 is a diagram illustrating an MTF curve of the optical system according to this example. As shown in fig. 12, at room temperature (25 ℃) the minimum value of the MTF value at a spatial frequency of 83 cycles/mm (corresponding to half the nyquist frequency) is about 72%, and thus good image forming performance is achieved. The minimum values of the MTF values at a spatial frequency of 83 cycles/mm at low temperature (-40 ℃) and high temperature (85 ℃) were about 51% and about 62%, respectively. In other words, it can be seen that by the temperature compensation performed by the cemented lens AT6, good image forming performance can be maintained even in the case where the ambient temperature changes.

Example 7

Example 7 of the present invention will be described below. Fig. 13 is a schematic diagram of a main portion in a section including an optical axis of an optical system according to example 7. A description of components in the optical system according to the present example that are equivalent to those in the optical system according to example 1 described above will be omitted.

The optical system according to this example has a focal length of 9.00mm and a half field angle of 60 °. The optical system according to this example includes a negative lens L71, a negative lens L72, a cemented lens AT7, an aperture stop S7, a positive lens L75, a cemented lens L10, a cemented lens L20, and a negative lens L710, which are arranged in order from the object side to the image side. The cemented lens AT7 is composed of a negative lens L73 and a positive lens L74 arranged in order from the object side to the image side, and the cemented lens L10 is composed of a positive lens L76 and a negative lens L77 arranged in order from the object side to the image side. The cemented lens L20 is composed of a positive lens L78 and a negative lens L79 arranged in order from the object side to the image side. The positive lens and the negative lens in the respective cemented lenses are cemented with each other by a cementing member such as an adhesive. An infrared cut filter F7 serving as a filter and a cover glass CG7 are arranged on the image side of the second negative lens L710 as the last lens. In this example, the cemented lens AT7 functions as a cemented lens for temperature compensation, thereby realizing both control of focal position variation due to environmental temperature change and correction of various aberrations.

Fig. 14 is a diagram illustrating an MTF curve of the optical system according to this example. As shown in fig. 14, at room temperature (25 ℃) the minimum value of the MTF value at a spatial frequency of 83 cycles/mm (corresponding to half the nyquist frequency) is about 77%, and thus good image forming performance is achieved. The minimum values of the MTF values at a spatial frequency of 83 cycles/mm at low temperature (-40 ℃) and high temperature (85 ℃) were about 51% and about 67%, respectively. In other words, it can be seen that by the temperature compensation performed by the cemented lens AT7, good image forming performance can be maintained even in the case where the ambient temperature changes.

Example 8

Example 8 of the present invention will be described below. Fig. 15 is a schematic view of a main portion in a section including an optical axis of the optical system according to example 8. A description of components in the optical system according to the present example that are equivalent to those in the optical system according to example 1 described above will be omitted.

The optical system according to this example has a focal length of 9.00mm and a half field angle of 60 °. The optical system according to this example includes a negative lens L81, a negative lens L82, a cemented lens AT8, an aperture stop S8, a positive lens L85, a cemented lens L10, a cemented lens L20, and a negative lens L810, which are arranged in order from the object side to the image side. The cemented lens AT8 is composed of a negative lens L83 and a positive lens L84 arranged in order from the object side to the image side, and the cemented lens L10 is composed of a positive lens L86 and a negative lens L87 arranged in order from the object side to the image side. The cemented lens L20 is composed of a positive lens L88 and a negative lens L89 arranged in order from the object side to the image side. The positive lens and the negative lens in the respective cemented lenses are cemented with each other by a cementing member such as an adhesive. An infrared cut filter F8 serving as a filter and a cover glass CG8 are arranged on the image side of the second negative lens L810 as the last lens. In this example, the cemented lens AT8 functions as a cemented lens for temperature compensation, thereby realizing both control of focal position variation due to environmental temperature change and correction of various aberrations.

Fig. 16 is a diagram illustrating an MTF curve of the optical system according to this example. As shown in fig. 16, at room temperature (25 ℃) the minimum value of the MTF value at a spatial frequency of 83 cycles/mm (corresponding to half the nyquist frequency) is about 70%, and thus good image forming performance is achieved. The minimum values of the MTF values at a spatial frequency of 83 cycles/mm at low temperature (-40 ℃) and high temperature (85 ℃) were about 67% and about 70%, respectively. In other words, it can be seen that by the temperature compensation performed by the cemented lens AT8, good image forming performance can be maintained even in the case where the ambient temperature changes.

Example 9

Example 9 of the invention will be described below. Fig. 17 is a schematic diagram of a main portion in a section including an optical axis of the optical system according to example 9. A description of components in the optical system according to the present example that are equivalent to those in the optical system according to example 1 described above will be omitted.

The optical system according to this example has a focal length of 9.00mm and a half field angle of 60 °. The optical system according to this example includes a negative lens L91, a negative lens L92, a cemented lens AT9, an aperture stop S9, a positive lens L95, a cemented lens L10, a cemented lens L20, and a negative lens L910, which are arranged in order from the object side to the image side. The cemented lens AT9 is composed of a negative lens L93 and a positive lens L94 arranged in order from the object side to the image side, and the cemented lens L10 is composed of a positive lens L96 and a negative lens L97 arranged in order from the object side to the image side. The cemented lens L20 is composed of a positive lens L98 and a negative lens L99 arranged in order from the object side to the image side. The positive lens and the negative lens in the respective cemented lenses are cemented with each other by a cementing member such as an adhesive. An infrared cut filter F9 serving as a filter and a cover glass CG9 are arranged on the image side of the second negative lens L910 as the last lens.

In this example, the cemented lens AT9 functions as a cemented lens for temperature compensation, thereby realizing both control of focal position variation due to environmental temperature change and correction of various aberrations.

Fig. 18 is a diagram illustrating an MTF curve of the optical system according to this example. As shown in fig. 18, at room temperature (25 ℃), the minimum value of the MTF value at a spatial frequency of 83 cycles/mm (corresponding to a half value of the nyquist frequency) is about 70%, and thus good image forming performance is achieved. The minimum values of the MTF values at a spatial frequency of 83 cycles/mm at low temperature (-40 ℃) and high temperature (85 ℃) were about 69% and about 69%, respectively. In other words, it can be seen that by the temperature compensation performed by the cemented lens AT9, good image forming performance can be maintained even in the case where the ambient temperature changes.

Reference example 1

Fig. 19 is a schematic view of a main portion in a section including an optical axis of the optical system according to reference example 1. A description of components in the optical system according to this reference example that are equivalent to those in the optical system according to example 1 described above will be omitted.

The optical system according to this reference example has a focal length of 16.15mm and a half field angle of 17.5 °. The optical system according to this reference example includes a first positive lens L101, a first negative lens L102, an aperture stop S10, a first cemented lens L10, a second cemented lens L20, a second positive lens L107, a third cemented lens AT10, and a second negative lens L1010, which are arranged in order from the object side to the image side. The first cemented lens L10 is composed of a negative lens L103 and a positive lens L104 arranged in order from the object side to the image side, and the second cemented lens L20 is composed of a negative lens L105 and a positive lens L106 arranged in order from the object side to the image side. The third cemented lens AT10 is composed of a negative lens L108 and a positive lens L109 arranged in order from the object side to the image side. The positive lens and the negative lens in the respective cemented lenses are cemented with each other by a cementing member such as an adhesive. The cover glass CG1 is arranged on the image side of the second negative lens L1010 as the last lens.

Fig. 20 is a diagram illustrating an MTF curve of an optical system according to this reference example. As shown in fig. 20, at room temperature (25 ℃) the minimum value of the MTF value at a spatial frequency of 68 cycles/mm (corresponding to half the nyquist frequency) is about 68%. The minimum values of MTF at a spatial frequency of 68 cycles/mm at low temperature (-40 ℃) and high temperature (85 ℃) were about 65% and about 56%, respectively.

Reference example 2

Fig. 21 is a schematic diagram of a main portion in a section including an optical axis of the optical system according to reference example 2. A description of components in the optical system according to this reference example that are equivalent to those in the optical system according to example 1 described above will be omitted.

The optical system according to this reference example has a focal length of 16.15mm and a half field angle of 17.5 °. The optical system according to this reference example includes a first positive lens L111, a first negative lens L112, an aperture stop S11, a first cemented lens L10, a second cemented lens L20, a second positive lens L117, a lens unit AT11, and a fourth negative lens L1110, which are arranged in order from the object side to the image side. The first cemented lens L10 is composed of a negative lens L113 and a positive lens L114 arranged in order from the object side to the image side, and the second cemented lens L20 is composed of a negative lens L115 and a positive lens L116 arranged in order from the object side to the image side. The lens unit AT11 is constituted by a second negative lens L118 and a third positive lens L119 arranged in order from the object side to the image side. The cover glass CG3 is arranged between the fourth negative lens L1110 as the last lens and the image plane IM 11.

Fig. 22 is a diagram illustrating an MTF curve of an optical system according to this reference example. As shown in fig. 22, at room temperature (25 ℃) the minimum value of the MTF value at a spatial frequency of 68 cycles/mm (corresponding to half the nyquist frequency) is about 63%. The minimum values of the MTF values at a spatial frequency of 68 cycles/mm at low temperature (-40 ℃) and high temperature (85 ℃) were about 60% and about 61%, respectively.

Numerical example

Hereinafter, numerical examples 1 to 11 corresponding to the above-described examples 1 to 9 and reference examples 1 and 2, respectively, will be indicated. In each numerical example, the surface number indicates the number of each optical surface from the object surface, r [ mm ] represents the radius of curvature of the i-th optical surface, and d [ mm ] represents the interval between the i-th optical surface and the (i+1) -th optical surface. As the material (lens material) of each lens in each numerical example, other materials having equivalent physical properties may be used.

In each numerical example, "E.+ -. P" means ". Times.10 ^±P ". The shape of each aspherical surface is represented by the following equation (aspherical surface equation):

where z represents the displacement amount of each aspherical surface from the surface vertex in the optical axis direction (this amount is called sagittal amount), h represents the height from the optical axis in the radial direction, c represents the curvature on the optical axis (this curvature is the inverse of the radius of curvature r), k represents the conic coefficient, and A, B, C, D, E and F represent the aspherical surface coefficients. As represented by the aspherical surface equation, each aspherical surface in this example has a rotationally symmetrical shape about the optical axis AX. The first term in the aspherical surface equation represents the sagittal amount of the basic spherical surface (reference spherical surface) with a radius of curvature r=1/c. The second and subsequent terms represent the sagittal amount of the aspheric surface component to be added to the base spherical surface.

(numerical example 1)

Surface data (-40 ℃ C.)

Surface data (25 ℃ C.)

Surface data (85 ℃ C.)

/>

Aspheric surface data-40 DEG C

+25℃

+85℃

(numerical example 2) surface data (-40 ℃ C.)

Surface data (25 ℃ C.)

/>

Surface data (85 ℃ C.)

(numerical example 3) surface data (-40 ℃ C.)

Surface data (25 ℃ C.)

/>

Aspheric surface data-40 DEG C

+25℃

+85℃

(numerical example 4) surface data (-40 ℃ C.)

/>

Surface data (85 ℃ C.)

/>

Aspheric surface data-40 DEG C

+25℃

+85℃

(numerical example 5) surface data (-40 ℃ C.)

Surface data (25 ℃ C.)

/>

Surface data (85 ℃ C.)

Aspheric surface data-40 DEG C

/>

+25℃

+85℃

(numerical example 6) surface data (-40 ℃ C.)

/>

Surface data (25 ℃ C.)

Surface data (85 ℃ C.)

/>

Aspheric surface data-40 DEG C

+25℃

+85℃

(numerical example 7)

Surface data (-40 ℃ C.)

Surface data (25 ℃ C.)

Surface data (85 ℃ C.)

/>

Aspheric surface data-40 DEG C

+25℃

+85℃

(numerical example 8) surface data (-40 ℃ C.)

/>

Surface data (25 ℃ C.)

/>

Surface data (85 ℃ C.)

Aspheric surface data-40 DEG C

/>

+85℃

(numerical example 9) surface data (-40 ℃ C.)

/>

Surface data (85 ℃ C.)

/>

Aspheric surface data-40 DEG C

+25℃

+85℃

(numerical example 10) surface data (-40 ℃ C.)

Surface data (25 ℃ C.)

/>

Surface data (85 ℃ C.)

(numerical example 11) surface data (-40 ℃ C.)

/>

Surface data (25 ℃ C.)

Surface data (85 ℃ C.)

/>

The optical system according to each numerical example is a fixed focal length optical system having a constant focal length (no zooming is performed), and a configuration in which focusing is not performed is adopted. In other words, the intervals between lenses constituting the optical system according to the respective numerical examples are always fixed. Variations in optical properties according to the movement of the individual lenses can be avoided. However, the optical system may be made capable of performing at least any one of zooming and focusing as needed, and the interval between lenses may be made variable for zooming or focusing.

The optical systems according to the respective numerical examples are assumed to be used in the visible range (486.1 nm to 656.27 nm) and are configured to perform good aberration correction in the entire visible range, but the wavelength range in which aberration correction is to be performed may be changed as needed. For example, each optical system may be configured to perform aberration correction only in a specific wavelength range within the visible range, or may be configured to perform aberration correction in an infrared wavelength range other than the visible range.

The following table lists values in inequalities for the optical system according to the above example and the reference example.

TABLE 1

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[ imaging device ]

Fig. 23 is a schematic diagram of main portions in the imaging device 70 according to an exemplary embodiment of the present invention. The imaging apparatus 70 according to the present exemplary embodiment includes an optical system (imaging optical system) 71 according to any one of the above examples, a light receiving element 72 that photoelectrically converts an image of an object formed by the optical system 71, and a camera body (housing) 73 that holds the light receiving element 72. The optical system 71 is held by a lens barrel (holding member), and is connected to the camera body 73. As shown in fig. 23, a display unit 74 that displays an image acquired by the light receiving element 72 may be connected to the camera body 73. Image sensors (photoelectric conversion elements) such as Charge Coupled Device (CCD) sensors and Complementary Metal Oxide Semiconductor (CMOS) sensors may be used as the light receiving element 72.

In the case where the imaging device 70 is used as a distance measuring device, an image sensor (imaging plane phase difference sensor) including pixels configured to divide light from an object into two and perform photoelectric conversion, for example, may be used as the light receiving element 72. When an object exists on the front focal plane of the optical system 71, no positional shift between images corresponding to the two separated light rays occurs on the image plane of the optical system 71. However, when the subject exists at a position other than the front focal plane of the optical system 71, a positional shift between images occurs. At this time, since the positional shift between the images corresponds to the amount of displacement of the subject from the front focal plane. Therefore, the amount of positional shift and the direction of positional shift between images are obtained using the imaging plane phase difference sensor, thereby measuring the distance to the subject.

The optical system 71 and the camera body 73 may be detachably attached to each other. In other words, the optical system 71 and the lens barrel may be formed as interchangeable lenses (lens devices). The optical system according to the respective examples described above is applicable to various optical apparatuses such as a telescope, a binoculars, a projector (projection apparatus), and a digital copying machine, in addition to imaging apparatuses such as a digital still camera, a silver-halide film camera, a video camera, an in-vehicle camera, and a monitoring camera.

[ vehicle-mounted System ]

Fig. 24 is a configuration diagram of the in-vehicle camera 10 and an in-vehicle system (driving assist device) 600 including the in-vehicle camera 10 according to the present exemplary embodiment. The in-vehicle system 600 is held by a movable member (movable device) such as an automobile (vehicle) and assists driving (handling) of the vehicle based on vehicle surrounding image information acquired by the in-vehicle camera 10. Fig. 25 is a schematic view of a vehicle (movable apparatus) 700 that serves as a movable apparatus and includes the in-vehicle system 600. Fig. 25 illustrates a case where the imaging range 50 of the in-vehicle camera 10 is set at the front portion of the vehicle 700, but the imaging range 50 may be set at the rear portion or the side portion of the vehicle 700.

As shown in fig. 24, the in-vehicle system 600 includes an in-vehicle camera 10, a vehicle information acquisition device 20, a control device (control unit, electronic Control Unit (ECU)) 30, and a warning device (warning unit) 40. The in-vehicle camera 10 includes an imaging unit 1, an image processing unit 2, a parallax calculating unit 3, a distance acquiring unit (acquiring unit) 4, and a collision determining unit 5. The image processing unit 2, the parallax calculating unit 3, the distance acquiring unit 4, and the collision determining unit 5 constitute a processing unit. The imaging unit 1 includes an optical system and an imaging plane phase difference sensor according to any of the examples described above.

Fig. 26 is a flowchart illustrating an operation example of the in-vehicle system 600 according to the present exemplary embodiment. Hereinafter, the operation of the in-vehicle system 600 will be described with reference to a flowchart.

First, in step S1, a plurality of pieces of image data (parallax image data) are acquired by capturing an image of a target object (subject) such as an obstacle or a pedestrian around a vehicle using the imaging unit 1.

In step S2, the vehicle information is acquired by the vehicle information acquisition device 20. The vehicle information is information including a vehicle speed, a yaw (yaw) rate, and a steering angle of the vehicle.

In step S3, the image processing unit 2 performs image processing on the pieces of image data acquired by the imaging unit 1. More specifically, the image processing unit 2 performs image feature analysis of analysis feature amounts (such as the number and direction of edges in image data, and density values). The image feature analysis may be performed on each of the pieces of image data, or may be performed on only a portion of the pieces of image data.

In step S4, the parallax calculating unit 3 calculates parallax (image shift) information between pieces of image data acquired by the imaging unit 1. Known methods such as a sequential similarity detection algorithm (sequential similarity detection algorithm, SSDA) and a region-related method may be used as the calculation method of the parallax information, and thus, a description of the calculation method is omitted in the present exemplary embodiment. The operations in steps S2, S3 and S4 may be performed in the order described above, or may be performed concurrently.

In step S5, the distance acquisition unit 4 acquires (calculates) information about the interval with the target object in the image captured by the imaging unit 1. The distance information may be calculated based on the parallax information obtained from the calculation by the parallax calculation unit 3 and the internal and external parameters of the imaging unit 1. The distance information refers to information about the relative position of the target object, such as the interval with the target object, the defocus amount, and the image shift amount. The distance information may directly indicate a distance value of the target object in the image, or may indirectly indicate information corresponding to the distance value.

In step S6, using the vehicle information acquired by the vehicle information acquisition device 20 and the calculated distance information from the distance acquisition unit 4, the collision determination unit 5 determines whether the distance to the target object falls within the preset range of the set distance. This configuration determines whether the target object is present within a set distance around the vehicle, thereby determining the possibility of collision between the vehicle and the target object. If the target object exists within the set distance (yes in step S6), the process proceeds to step S7. In step S7, the collision determination unit 5 determines "possibility of collision exists". If the target object does not exist within the set distance (no in step S6), the process proceeds to step S8. In step S8, the collision determination unit 5 determines "there is no possibility of collision".

If the collision determination unit 5 determines "there is a possibility of collision", the collision determination unit 5 notifies the control device 30 and/or the warning device 40 of the determination result (transmits the determination result to the control device 30 and/or the warning device 40). At this time, the control device 30 controls the vehicle based on the determination result obtained by the collision determination unit 5. The warning device 40 issues a warning to a user (driver, passenger, user) of the vehicle based on the determination result obtained by the collision determination unit 5. The notification of the determination result may be performed only by at least one of the control device 30 and the warning device 40.

The control device 30 controls the movement of the vehicle by outputting a control signal to a driving unit (engine, motor, etc.) of the vehicle. For example, the control device 30 performs control of the vehicle, such as applying a brake, releasing an accelerator pedal, turning a steering wheel, or controlling engine and/or motor output, by generating control signals for causing wheels to generate braking forces. The warning device 40 gives a warning to the user by, for example, providing a warning sound (warning call), displaying a warning message on a screen of the car navigation system, and/or vibrating a seat belt or a steering wheel.

As described above, the in-vehicle system 600 according to the present exemplary embodiment enables the target object to be efficiently detected by the above-described process, thereby avoiding collision between the vehicle and the target object. In particular, the application of the optical system according to any one of the above examples to the in-vehicle system 600 makes it possible to perform target object detection and collision determination over a wide angle of view while reducing the size of the entire in-vehicle camera 10 and enhancing the degree of flexibility in arrangement.

In the present exemplary embodiment, a configuration is used in which the in-vehicle camera 10 includes only one imaging unit 1, the imaging unit 1 including an imaging plane phase difference sensor, but the configuration is not limited thereto, and a stereo camera including two imaging units may be employed as the in-vehicle camera 10. In this case, it is possible to perform a process similar to the above-described process by simultaneously acquiring image data by the two imaging units synchronized and using the two pieces of image data without using the imaging plane phase difference sensor. If the difference between the image capturing times of the two imaging units is known, then the two imaging units do not need to be synchronized.

For the calculation of the distance information, various exemplary embodiments may be considered. As an example, a case will be described in which an image sensor of a pupil division type (pupil division type) including a plurality of pixel portions regularly arranged in a two-dimensional array is used as the image sensor included in the imaging unit 1. In the pupil-divided image sensor, one pixel portion includes a microlens and a plurality of photoelectric conversion units, receives a pair of light rays passing through different areas of a pupil of an optical system, and outputs a pair of image data from the respective photoelectric conversion units.

The image shift amounts of the respective areas are calculated by calculating the correlation between a pair of image data, and image shift map data indicating the distribution of the image shift amounts is calculated by the distance acquisition unit 4. Alternatively, the distance acquisition unit 4 may also convert the image shift amount into a defocus amount, and generate defocus map data indicating a distribution of defocus amounts (distribution on a two-dimensional surface of a captured image). The distance acquisition unit 4 may acquire distance map data indicating the interval from the target object converted from the defocus amount.

The in-vehicle system 600 and the movable apparatus 700 may include a notification device (notification unit) for notifying a manufacturer (producer) of the in-vehicle system 600 and/or a distribution source (distributor) of the movable apparatus 700 of the collision in the case where the movable apparatus 700 collides with an obstacle with any possibility. For example, a notification device that transmits information (collision information) about a collision between the movable device 700 and an obstacle to a preset external notification destination by email or the like may be employed as the notification device.

In this way, by adopting a configuration in which the destination is automatically notified to the outside using the notification device, measures such as inspection and repair can be promptly taken after the occurrence of a collision. The notification destination of the collision information may be any notification destination set by an insurance company, medical institution, police, or user. The information is not limited to collision information, and the notification device may be configured to notify the notification destination of failure information of the respective components or consumption information of the consumable. The detection of the collision may be performed using distance information acquired based on an output from the imaging unit 1, or may be performed by another detection unit (sensor).

In the present exemplary embodiment, the in-vehicle system 600 is applied to driving assistance (collision injury reduction), but the application is not limited thereto, and the in-vehicle system 600 may be applied to cruise control (with all-vehicle speed tracking function) or automatic driving. The application of the in-vehicle system 600 is not limited to vehicles (such as automobiles). For example, the in-vehicle system 600 is suitable for use with a movable member such as a ship, an aircraft, or an industrial robot. The application of the in-vehicle system 600 is not limited to a movable member, and the in-vehicle system 600 is applicable to various devices using object recognition, such as an Intelligent Transportation System (ITS).

Modified example

Exemplary embodiments and examples of the present invention have been described above, but the present invention is not limited to the exemplary embodiments and examples. Various combinations, modifications, and variations may be made within the scope of the gist thereof.

For example, in the above-described exemplary embodiment, a description is provided of a case where the second control unit has a function as the collision determination unit (determination unit), but the configuration is not limited thereto. For example, in the in-vehicle system, a collision determination unit different from the second control unit may be provided. In other words, the second control unit is required to have at least a function as a distance calculation unit (distance information acquisition unit). The first control unit and the second control unit may be provided outside the distance measuring device (e.g., inside the vehicle) when necessary.

While the invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims (20)

1. An optical system, comprising:

a negative lens and a positive lens adjacent to each other,

wherein the following inequality is satisfied:

DAB 0.00.ltoreq.DAB 1.00, and

0.80≤RA/RB≤1.20,

wherein DAB [ mm ] represents the distance between the negative lens and the positive lens on the optical axis, and RA and RB represent the radii of curvature of the facing lens surfaces of the negative lens and the positive lens, respectively, and

wherein the following inequality is satisfied:

0.00≤|NA-NB|≤0.20，

0.00 < v > A-v > B < 20.00, and

4.2≤|dnA/dt-dnB/dt|，

wherein NA and NB denote refractive indices of the negative and positive lenses, respectively, with respect to d-line, vA and vB denote Abbe numbers of the negative and positive lenses, respectively, with respect to d-line, and dnA/dt [10 ] ^-6 /℃]And dnB/dt [10 ] ^-6 /℃]The temperature coefficients of the refractive index of the negative and positive lenses with respect to the d-line at 20 ℃ to 40 ℃ are represented, respectively, and either dnA/dt or dnB/dt has a negative sign.

2. The optical system of claim 1, wherein the following inequality is satisfied:

2.9<|βA-βB|<20.9,

wherein alpha A10 ^-6 /℃]And alpha B10 ^-6 /℃]The linear expansion coefficients of the negative and positive lenses are shown, respectively, βa=αa-dnA/dt/(NA-1), and βb=αb-dnB/dt/(NB-1).

3. The optical system according to claim 1, wherein a maximum value of any one of βa and βb is 8.0 or more, wherein αa [10 ] ^-6 /℃]And alpha B10 ^-6 /℃]The linear expansion coefficients of the negative and positive lenses are shown, respectively, βa=αa-dnA/dt/(NA-1), and βb=αb-dnB/dt/(NB-1).

4. The optical system of claim 1, wherein the negative lens and the positive lens are cemented to each other.

5. The optical system of claim 4, wherein the following inequality is satisfied:

0.10×10 ^-3 <|Dk/R|<1.00,

where R represents a radius of curvature of a cemented surface of the negative lens and the positive lens, and Dk represents an effective diameter.

6. The optical system according to claim 1, wherein the facing lens surfaces of the negative lens and the positive lens each have a convex shape protruding toward the object side.

7. The optical system according to claim 1, further comprising a first cemented lens and a second cemented lens arranged consecutively in order from the object side to the image side.

8. The optical system according to claim 7, wherein the first cemented lens and the second cemented lens each include a negative lens having a concave surface on the object side and a positive lens cemented to the negative lens, which are arranged in order from the object side to the image side.

9. The optical system according to claim 7, wherein the cemented surfaces of the first cemented lens and the second cemented lens each have a convex shape protruding toward the object side.

10. The optical system of claim 1, further comprising an aperture stop disposed closest to the object.

11. An image forming apparatus comprising:

the optical system according to any one of claims 1 to 10; and

an image sensor configured to capture an image of an object via the optical system.

12. An in-vehicle system, comprising:

the imaging device of claim 11; and

and a determining unit configured to determine a possibility of collision between the vehicle and the object based on the distance information of the object acquired by the imaging device.

13. The in-vehicle system according to claim 12, further comprising a control device configured to output a control signal for causing a drive unit of the vehicle to generate the braking force in a case where it is determined that there is a possibility of collision between the vehicle and the object.

14. The in-vehicle system according to claim 12, further comprising a warning device configured to issue a warning to a user of the vehicle in case it is determined that there is a possibility of collision between the vehicle and the object.

15. The in-vehicle system according to any one of claims 12 to 14, further comprising a notification device configured to transmit information about a collision between the vehicle and the object to an external destination.

16. A movable apparatus comprising the imaging apparatus according to claim 11, wherein the movable apparatus is movable while holding the imaging apparatus.

17. The movable apparatus according to claim 16, further comprising a determination unit configured to determine a possibility of collision with the object based on the distance information of the object that has been acquired by the imaging apparatus.

18. The movable apparatus according to claim 17, further comprising a control unit configured to output a control signal for controlling the movement in the case where it is determined that there is a possibility of collision with the object.

19. The mobile device of claim 17, further comprising a warning unit configured to alert a user of the mobile device if it is determined that there is a possibility of collision with the object.

20. The movable apparatus according to any one of claims 16 to 19, further comprising a notification unit configured to transmit information about a collision with an object to an external destination.