JP2002131509A - Cemented doublet, lens device using the same and manufacturing method for cemented doublet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cemented doublet having the high degree of freedom in design for compensating aberration and having small eccentricity, and a manufacturing method for the cemented doublet, and further to provide a lens device having high resolution. SOLUTION: This cemented doublet is constituted of a 1st lens element 11 and a 2nd lens element 12. In such a case, a lens element having a concave surface 17 including an effective area on an opposed surface (back surface 14) opposed to the 2nd lens element 12 and formed to come into contact with the 2nd lens element 12 at an edge 19 being the outer edge of the concave surface 17 is used as the 1st lens element 11. The 1st lens element 11 is stuck to the 2nd lens element 12 on the outside of the concave surface 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compound lens, a lens device using the compound lens, and a method of manufacturing a compound lens.

[0002]

2. Description of the Related Art In recent years, the progress of personal computers,
In conjunction with the spread, electronic still cameras are rapidly spreading. The total number of pixels of a solid-state imaging device used in an electronic still camera exceeds 1 million pixels, and recently, the total number of pixels is 300
Electronic still cameras equipped with a solid-state image sensor having more than 10,000 pixels have also been commercialized. In addition, a video camera is equipped with a function of capturing a high-quality still image in addition to a moving image.

As an imaging lens of an electronic still camera,
Initially, a fixed focus lens was mounted, but recently a zoom lens with a zoom ratio of 2 to 3 has been mounted. In addition, with the development of technology for manufacturing aspherical glass lenses by molding, aspherical glass molded lenses have been introduced as zoom lenses for video cameras,
Attempts have been made to reduce the number of lens components, improve imaging characteristics, shorten the overall optical length of the lens device, and reduce costs. Similarly, an aspherical glass molded lens has been introduced into a zoom lens for an electronic still camera.

The image quality of an image photographed by an electronic still camera is governed by an imaging lens, a solid-state imaging device, and a signal processing circuit. Therefore, the imaging lens has a high resolution of the entire screen, uniformity of resolution and uniformity of illuminance. Is also required to be good. Particularly, in view of the recent increase in the number of pixels of the solid-state imaging device, improvement in resolution is desired.

To improve the resolution, the design performance of the zoom lens with respect to the resolution is improved, and a lens material having a small refractive index error is used, and the processing accuracy of the lens element, the lens barrel and the spacer, and the assembly accuracy are improved. Need to be improved.

[0006]

However, there is a problem that the cost of the imaging lens is increased if the processing accuracy and the assembly accuracy of the components are improved. In addition, although lens design is performed so that the sensitivity related to eccentricity does not become extremely large, the sensitivity related to eccentricity of all lens surfaces cannot be sufficiently reduced.
There is a limit to improving the resolution.

[0007] On the other hand, as means for improving the assembling accuracy, joining of two lens elements and abutment of two lens elements can be mentioned.

In a compound lens formed by bonding, a lens element having a concave surface and a lens element having a convex surface having the same radius of curvature as the concave surface are joined by the concave surface and the convex surface, and an adhesive is applied to the entire effective area of each surface. It is configured to be fixed by. In this case, the thickness of the adhesive is, for example, 5 μm to 2 μm.
Since the thickness can be made as thin as 0 μm, the spacing error between the opposing lens surfaces becomes very small. Therefore, the eccentricity between the opposed lens surfaces can be made very small, and the assembling accuracy can be improved.

However, since the two lens surfaces to be joined must be spherical surfaces having the same radius of curvature, the number of parameters that can be used for aberration correction is reduced by one as compared with a case where two lens elements are separated. As a result, the degree of freedom in designing for aberration correction is reduced, so that it is difficult to obtain a desired imaging performance.

[0010] The compound lens by abutting is constituted by bringing two lens elements into direct contact with each other outside the effective area of each other, and maintaining that state by a lens barrel. In this case, since a spacer that easily causes a dimensional error is not required, a gap error between the opposing lens surfaces can be reduced, and thus the eccentricity between the opposing lens surfaces can be extremely reduced. However, since it is necessary to pay attention to the eccentricity of the lens elements in the lens barrel, it is necessary to reduce the eccentricity of each lens element, and in particular, it is necessary to tighten the fitting tolerance between each lens element and the lens barrel. is there.

Recently, it has been practiced to center some lens elements having a high sensitivity to eccentricity. The alignment is
The purpose is to adjust the position of the lens element so that the eccentricity of the entire lens system or the lens group is reduced. But,
It can be said that it is difficult to improve the assembling accuracy only by alignment, and therefore it is difficult to improve the resolution.

An object of the present invention is to provide a compound lens having a high degree of freedom in designing for aberration correction, small eccentricity and a method of manufacturing the compound lens, and to provide a lens device with higher resolution.

[0013]

According to the present invention, there is provided a compound lens having at least a first lens element and a second lens element, wherein the first lens element has a first lens element and a second lens element. Has a concave surface that covers the effective area on the opposing surface facing the second lens element, and contacts the second lens element at the outer edge of the concave surface or outside the concave surface,
Further, it is characterized by being fixed to the second lens element outside the concave surface.

The compound lens according to the present invention is more preferable when the following embodiments (1) and (2) are adopted. (1) The opposing surface of the second lens element is formed as a convex surface having a central portion as an effective area and an outer peripheral portion as an area outside the effective area, and the outside of the concave surface in the first lens element is a conical surface or An annular groove formed on a plane perpendicular to the optical axis, the outside of the concave surface of the first lens element and the outside of the effective area of the second lens element surrounding the outer periphery of the compound lens; An embodiment in which the groove is filled with an adhesive. (2) The second lens element has a concave surface including an effective area on the opposing surface and a plane perpendicular to the optical axis, and the first lens element has a plane outside the concave surface perpendicular to the optical axis. And bonding to the plane of the second lens element at the plane.

As described above, in the compound lens of the present invention, unlike the compound lens formed by conventional joining, the opposing surfaces of the lens elements do not need to be constituted by the concave surface and the convex surface having the same radius of curvature. The degree of freedom in designing for aberration correction in the effective region can be increased. The “effective area” in the present invention refers to an area that functions normally as a lens surface on the surface of a lens element.

Further, since the two lens elements are bonded in the compound lens of the present invention, when the compound lens of the present invention is installed in the lens barrel, the eccentricity between the two lens elements may cause the processing of the lens barrel. It can be said that there is no influence from accuracy.

In the composite lens according to the present invention, the adhesive preferably contains a light absorbing material. Furthermore,
It is preferable that a light-absorbing film formed of a light-absorbing material is provided on at least a part or all of the surface of the at least one lens element that does not constitute an effective area.

According to a first aspect of the present invention, there is provided a method of manufacturing a compound lens, comprising the steps of: Contacting the second lens element at the outer edge of the concave surface, adjusting the positional relationship by the centering means so as to reduce the eccentricity between the lens elements in contact with each other, and applying an adhesive to the groove. Filling and curing the adhesive.

A second aspect of the method for manufacturing a compound lens according to the present invention is the method for manufacturing a compound lens according to the above (2), wherein the first lens element and the second lens element are provided. Applying an adhesive to at least one of the planes and contacting the first lens element and the second lens element such that the planes overlap each other;
The method is characterized by including at least a step of adjusting a positional relationship so that eccentricity between lens elements in a contact state is reduced, and a step of curing the adhesive.

As described above, in the method of manufacturing a compound lens according to the present invention, the positional relationship between the two lens elements is adjusted by, for example, the centering means, and the lens elements are bonded in this state, so that the eccentricity is extremely small. Composite lenses can be made.

Next, in order to achieve the above object, a lens device according to the present invention has at least the compound lens according to the present invention, and a lens barrel configured to be able to arrange the compound lens therein. A lens device, wherein the compound lens is disposed inside the lens barrel such that only a side surface of any one of the lens elements constituting the compound lens contacts an inner wall of the lens barrel. And

As described above, in the lens device according to the present invention, the use of the compound lens with extremely small eccentricity reduces the decrease in resolution due to the eccentricity, thereby providing a high-resolution lens device. it can. Further, in the compound lens, only one of the plurality of lens elements constituting the compound lens is held in contact with the inner wall of the lens barrel. The outer diameter tolerance, that is, the inner diameter tolerance of the inner wall of the lens barrel to which the side surface of the lens element is close becomes very loose. Therefore, the cost of the lens element that does not contact the inner wall of the lens barrel can be reduced. That is, according to the present invention, it is possible to provide a low-cost, high-resolution lens device.

[0023]

(Embodiment 1) Hereinafter, a compound lens, a method of manufacturing the compound lens, and a lens apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view illustrating the compound lens according to the first embodiment of the present invention. FIG. 2 is a schematic diagram for explaining the eccentricity of the lens element. FIG. 3 is a schematic diagram for explaining the eccentricity of the lens element group. FIG. 4 is a cross-sectional view illustrating the method of manufacturing the compound lens according to the first embodiment of the present invention. FIG. 5 is a cross-sectional view illustrating the lens device according to the first embodiment.

As shown in the example of FIG. 1, the compound lens according to the first embodiment of the present invention includes at least two lens elements (11, 12). In the example of FIG. 1, the compound lens of the present invention includes a first lens element (hereinafter, referred to as “first lens”) 11 and a second lens element (hereinafter, “second lens element”).
Lens. " ) 12 and the first lens 11 is on the object side. The second lens 12 is formed so as to have an outer diameter larger than that of the first lens 11. In this specification, the surface on the object side of the lens element is called a front surface, and the surface on the opposite side is called a rear surface. Therefore, the rear surface 14 of the first lens 11 is an opposing surface, and the front surface 15 of the second lens 12 is an opposing surface.

The facing surface (rear surface 14) of the first lens element 11 facing the second lens element 12 has a concave surface 17 including an effective area. The diameter (effective diameter) of the effective area on the concave surface 17 is the diameter of the concave surface (edge diameter).
(See Table 1 below). In the example of FIG. 1, a concave surface including the effective area is also formed on the front surface 13 of the first lens 11. Second lens 1
The two surfaces are formed as convex surfaces having a central portion as an effective region and an outer peripheral portion as a region outside the effective region.

The effective area of the front surface 13 and the rear surface 14 of the first lens 11 and the effective area of the front surface 15 of the second lens 12 are all spherical. On the other hand, the second lens 1
The effective area of the rear surface 2 is formed as an aspheric surface. The absolute value of the radius of curvature of the concave surface 17 on the rear surface 14 of the first lens 11 is smaller than the absolute value of the radius of curvature of the front surface 15 of the second lens 12. Both the first lens 11 and the second lens 12 are made of optical glass.

In the example of FIG. 1, the outside of the concave surface 17 is formed by a conical surface 18. For this reason, the first lens 11
The outside of the concave surface 17 and the area outside the effective area of the second lens 12 form an annular groove surrounding the outer periphery of the compound lens. The outer edge of the concave surface 17 is an annular edge 19 protruding toward the second lens 12, and the first lens 11
Is in contact with the front surface 15 of the second lens 12 by the edge 19. On the opposing surface (front surface 15) of the second lens 12, there is an effective area inside the contact portion with the edge 19.

The cross section of the groove formed by the conical surface 18 and the area outside the effective area on the front surface 15 of the second lens has a V-shape. The groove 21 having a V-shaped cross section is filled with an adhesive 21. The first lens 11 and the second lens 12 are fixed by the adhesive 21. However, the method of fixing the lens elements in the present invention is not limited to such a method using an adhesive, and may be a method using fusion or a method using optical bonding without using an adhesive.

The present embodiment is not limited to the embodiment shown in FIG. 1. A groove having a V-shaped cross section as described above is formed between the first lens and the second lens. There is no particular limitation if. For example, the rear surface 14 of the first lens 11 is formed as a convex surface, and the second lens 12
A concave surface and a conical surface can also be formed on the front surface 15 of the light emitting element.
Further, the rear surface 14 of the first lens 11 may be formed as a concave surface and a conical surface as shown in FIG. 1, and the front surface 15 of the second lens 12 may be formed as a flat surface or a concave surface.

In the example shown in FIG. 1, an anti-reflection film (not shown) is provided on the front and rear surfaces of the two lens elements, that is, on an effective area of a total of four surfaces. Side surface 22 of first lens 11
A light-absorbing film is provided on the conical surface 23 provided on the front surface 13. Reference numeral 27 denotes a side surface of the second lens 12. Table 1 shows numerical data of the complex lens shown in FIG. 1 and Table 2 shows aspherical data.

[0031]

[Table 1]

[0032]

[Table 2]

In Table 1, the surface with the * mark on the radius of curvature is an aspheric surface, and the aspheric surface is represented by the following equation (1). Here, h is the height of the point on the lens surface from the optical axis, z is the amount of sag, r is the paraxial radius of curvature, κ is the conic constant, a4, a6, a
8, a10 are fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients, respectively.

[0034]

(Equation 1)

In the present invention, the rear surface 1 of the first lens 11
The concave surface 17 in 4 and the front surface 15 of the second lens 12 can also be formed as aspherical surfaces. Such a lens element having at least one aspheric surface can be manufactured by a molding technique. When the first lens 11 is manufactured by a molding technique, the cross-sectional shape of the tip portion of the edge formed at the boundary between the concave surface 17 and the conical surface 18 may be a substantially arc shape due to the convenience of die processing. Also, the front surface 1 of the second lens 12
Reference numeral 5 denotes an aspherical portion of the effective area for bringing the edge 19 of the first lens 11 into stable contact with the front surface 15 of the second lens 12, and a portion in contact with the edge 19 of the first lens 11 and its vicinity. May be a spherical surface.

Next, the eccentricity of the lens element will be described with reference to FIG. In FIG. 2, the lens surfaces S1 and S2 of the lens element 20 are both spherical. When the lens surface is a spherical surface, one lens element has only one spherical center (center of curvature) on each lens surface. When the lens surface is a spherical surface, there is only one spherical center corresponding to one spherical surface, and therefore, for example, the first lens 11 shown in FIG. 1 has two spherical centers. A straight line L connecting the spherical center C1 of the lens surface S1 and the spherical center C2 of the lens surface S2 is the optical axis. Each of the two lens surfaces S1 and S2 is rotationally symmetric about the optical axis L. Center N of side surface 201 of lens element
The length of the perpendicular from the optical axis L to the optical axis L is the amount of eccentricity of the lens element. Note that the center N of the side surface 201 of the lens element is a point that coincides with the center of the one having the smallest radius among the spherical surfaces circumscribing the lens element 20.

Next, the eccentricity of a lens element group composed of k lens elements and all lens surfaces of each lens element being spherical will be described with reference to FIG. When there are k lens elements, there are a total of 2k spherical centers on the lens surface, but there is generally no straight line passing through each spherical center. Therefore, FIG.
As shown in the figure, considering a straight line L, the spherical center Cj on the j-th surface
The length of a perpendicular drawn from (i = 1, 2,...) To this straight line L is ej, and a straight line that minimizes E defined by the following equation 2 is considered as a reference axis. Since there is generally only one such reference axis, E can be considered as an overall eccentricity.

[0038]

(Equation 2)

The state in which the eccentricity is small is a state in which E is very close to zero. E is changed by moving any lens element parallel to the reference axis or by inclining the lens element. Therefore, E can be reduced by translating some or all of the lens elements in the appropriate direction or tilting them in the appropriate direction, and if all lens elements are ideal lens elements, then E = It can be set to 0. Note that even in the configuration in which the two lens elements shown in FIG. 1 are abutted, the perpendicularity between the circle formed by the edge 19 of the first lens 11 and the optical axis of the first lens 11 is related to E. It is necessary to pay attention to this point when processing the edge 19 of the lens 11.

When the lens surface is aspheric, there is no equivalent to the spherical center of the spherical lens. Therefore, since the center of the aspherical surface can be approximated by a spherical surface, the center of curvature of this spherical surface can be considered as a spherical center, or the spherical center closest to the aspherical surface can be assumed to be the spherical center. It is good to think.

In the compound lens shown in the example of FIG. 1, the first lens 11 is fixed, and the second lens 12 is shifted while being in contact with the edge 19 of the first lens 11 so that the two spheres of the second lens 12 are moved. You can move your mind. Therefore,
In order that E when k = 2 in Equation 2 becomes as small as possible,
By moving the second lens 12 in an appropriate direction and an appropriate amount with respect to the first lens 11, the eccentricity between the first lens 11 and the second lens 12 can be reduced. The second
When moving the lens 12, the rear surface 1 of the second lens 12
The ball center of No. 6 moves largely, but the ball center of the front face 15 hardly moves. This positions the front surface 15 of the second lens 12
This is because the lens abuts against the edge 19 of the lens 11.

When two lens elements are fixed by conventional bonding, the opposing surfaces of the lens elements are limited to spherical surfaces having the same radius of curvature, so that the degree of freedom in designing for aberration correction is low. I can say. On the other hand, in the compound lens according to the present embodiment as shown in FIG. 1, the opposing surfaces of the lens elements do not need to be spherical surfaces having the same radius of curvature, and can be set to some extent freely. It can be said that the degree of freedom of design for aberration correction is higher than that of the compound lens of the above. Therefore, when the lens device is configured using the compound lens according to the present embodiment, the aberration of the entire lens device can be more favorably corrected. Moreover,
Since the lens unit is integrated with a small eccentricity before being incorporated into the lens barrel, a reduction in resolution due to the eccentricity of the entire lens device can be suppressed.

Next, a method of manufacturing the compound lens shown in FIG. 1 will be described with reference to FIG. The composite lens shown in FIG. 1 is manufactured by the following steps (1) to (3). (1) First, the first lens 11 is brought into contact with the second lens 12 at the outer edge of the concave surface 17, that is, the edge 19. (2) First lens 11 and second lens 12 in contact state
And the positional relationship is adjusted so that the eccentricity between them is reduced. (3) Fill the V-shaped groove with an adhesive and cure the adhesive.

In the example shown in FIG. 4, a centering means such as a bell clamp device is used for adjusting the positional relationship. The superimposed first lens 11 and second lens 12 are sandwiched between two cylindrical holders 25 and 26 constituting a bell clamp device. Each of the cylindrical holders 25 and 26 is configured to be rotatable about a common shaft 24 as a rotation center axis. The positional relationship is adjusted by applying an appropriate pressure by the cylindrical holders 25 and 26 while the first lens 1
This is performed by slightly shifting the position of the second lens 12 with the position of 1 fixed.

In order to reduce the eccentricity by adjusting the positional relationship, an eccentricity measuring device and a lens element fine movement device can be used. The eccentricity measuring device is a device that irradiates two parallel lens elements (11, 12) with nearly parallel light, and observes a spot image by transmitted light or reflected light with a microscope. When using an eccentricity measuring device,
As the lens holder, the lens element can be sandwiched by its side surface, and the center axis of the lens holder (axis 2 shown in FIG. 4)
4) is used in which a window is formed so that parallel light can pass therethrough.

For example, when transmitted light is used, the second lens 12 is mounted on the lens holder with the front surface 15 facing the outside of the lens holder, and parallel light is irradiated from the rear surface 16 through the window of the lens holder. The position of the lens holder is adjusted so that the spot image formed by transmitting the parallel light through the second lens 12 is located at the center of the field of view of the microscope arranged on the front surface 15 side. Next, the first lens 11 is brought into contact with the second lens 12, and the position of the first lens 11 may be adjusted so that the spot image formed by passing through the two lens elements is located at the center of the field of view of the microscope. .

In the case of using reflected light, the second lens 12 is mounted on the lens holder in the same manner as described above, and parallel light is irradiated from the front surface 15 side.
The position of the lens holder is adjusted so that the spot image reflected by the lens and further transmitted through the front surface 15 is located at the center of the field of view of the microscope. Next, the first lens 11 is brought into contact with the second lens 12, and the position of the first lens 11 is adjusted so that the spot image formed by reflection on the front surface of the first lens 11 is located at the center of the field of view of the microscope. I just need.

By adjusting such a positional relationship, the first
A state in which the eccentricity of the four surfaces of the lens 11 and the second lens 12 is small is created, and the state is maintained.

Further, in the example shown in FIG. 4, an ultraviolet curable resin is used as the adhesive filling the V-shaped groove formed between the first lens 11 and the second lens 12. . Curing of the adhesive is performed by irradiation of ultraviolet rays. If the adhesive 21 rises from the side surface 27 of the second lens 12, the completed compound lens may not be able to be inserted into the lens barrel. Therefore, after the adhesive 21 is cured, the excess adhesive is removed. Is a preferred embodiment.

When the adhesive 21 is filled into the V-shaped groove, if the viscosity of the adhesive is low and the wettability is good, it is advisable to apply the adhesive to a part of the V-shaped groove, and the capillary phenomenon is caused. As a result, the adhesive spreads instantaneously over the entire V-shaped groove. When the viscosity of the adhesive is high, it is preferable to discharge the adhesive by a constant amount at a constant speed by an automatic discharge device while rotating the cylindrical holders 25 and 26 at a constant speed. If an automatic ejection device is used, the adhesive can be filled into the groove without excess or shortage. By the curing of the adhesive, a composite lens in which the first lens 11 and the second lens 12 are fixed with small eccentricity is completed.

In the present invention, as the adhesive 21, in addition to the above-described ultraviolet curable resin, a heat curable resin, a resin having both characteristics of ultraviolet curable and heat curable can be used. Since the ultraviolet curable resin is cured in a short time by irradiation with ultraviolet light, there is an advantage that mass productivity can be improved. When a thermosetting resin is used, since the time required for curing is long, the two lens elements 11 and 12 are removed by a bell clamp device so that the two lens elements (11 and 12) do not shift during heating. It is necessary to sandwich it.

When a resin having both ultraviolet curability and heat curability is used, an adhesive is filled in a V-shaped groove after alignment, and the adhesive is temporarily cured by irradiation with ultraviolet light. It is good to remove it from the clamp device and completely cure it in the heating chamber. When the ultraviolet curable resin is temporarily cured in this manner, the positional relationship between the two lens elements (11, 12) is fixed, so that the two lens elements (11, 12) can be fixed even during heat curing. No displacement occurs between them.

The UV-curable resin is generally transparent or pale yellow, but if a light-absorbing material is added to the UV-curable resin moderately, the light-absorbing material absorbs unnecessary light generated in the composite lens, thereby lowering the contrast. Can be suppressed. However, since the ultraviolet ray does not reach the deep part by the light absorbing material, there arises a problem that only the surface of the resin is cured. However, if an ultraviolet-curable resin and a heat-curable resin are mixed together and an appropriate light-absorbing material is used as an adhesive, the vicinity of the surface of the resin is cured by the irradiation of ultraviolet light, so that the adhesive strength is weak. The positional relationship between the lens elements can be maintained. Therefore, if the part of the resin that is not cured by the ultraviolet rays is cured by heating later, a sufficient adhesive force can be secured.

In this embodiment, the area where the adhesive 21 contacts the first lens 11 or the second lens 12 may be appropriately set in consideration of the adhesive strength, the outer diameter of the lens device, and the like. Note that the filled adhesive 21 has a ring shape, and the outer diameter of this ring is uniquely determined by the outer shape of the lens element. What is necessary is just to set the width of the adhesive to be performed. Note that the width of the filled adhesive referred to herein is the width of FIG.
This means the distance from the edge 19 to the outer edge of the conical surface 18.

Specifically, two lens elements (11, 1
When the outer diameter of 2) is 20 mm or less, the width of the adhesive to be filled is preferably 0.3 mm to 2 mm. If the width of the adhesive to be filled is smaller than 0.3 mm, sufficient adhesive strength cannot be obtained. If the width is larger than 2 mm, the outer diameter of the compound lens becomes larger, and the outer diameter of the lens device using the compound becomes larger. It is because. When the outer diameter of each of the two lens elements (11, 12) is 20 mm or more, the width of the filled adhesive is set to about 10% of the outer diameter of the lens element having the smaller outer diameter. Is preferred.

In order to reduce the outer diameter of the composite lens, it is a preferable embodiment that the width of the adhesive to be filled is made as small as possible and the adhesive strength is secured. Therefore, it is preferable that the adhesive is filled over the entire circumference of the V-shaped groove as shown in the example of the figure. However, the present invention is not limited to this, and as long as necessary adhesive strength can be ensured, the adhesive may be filled in a part of the V-shaped groove, preferably at least three parts. good.

In the examples shown in FIGS. 1 and 4, the edge 19 of the first lens 11 and the front surface 1 of the second lens element 12 are used.
The portion in contact with 5 prevents the adhesive 21 from entering the effective area of each lens element. There is no practical problem if the amount of the adhesive 21 that has penetrated into the effective area is small with respect to the area of the effective area. However, if the amount of the intruded adhesive 21 is large, a problem occurs in practical use.
As for 1, it is necessary to select one having an appropriate viscosity and wettability.

Normally, if the viscosity of the adhesive 21 is too high or the wettability is not good, there is a problem that the adhesive 21 does not penetrate deep into the V-shaped groove. Is too low, a problem arises in that the adhesive 21 easily enters the effective area. Therefore, in the present invention, the surface on which the adhesive is to be applied is thoroughly washed, and the viscosity of the adhesive 21 at room temperature is 1.0 × 10 ⁻³ Pa · s to 1.0.
It is preferable to use one having 0 × 10 ² Pa · s.

Further, in order to prevent the adhesive 21 from entering the effective area, the angle of the V-shaped groove is also important.
The angle of the V-shape may be appropriately set according to the viscosity of the adhesive used. For example, if an adhesive having the above-mentioned viscosity is used, it may be set to about 5 to 30 degrees.

When an antireflection film is provided on the front surface and the rear surface of the lens element, it is necessary to pay attention to the adhesion strength of the antireflection film. This is because if the adhesive force between the glass and the antireflection film is weak, the adhesive force between the two lens elements will be weak. Therefore, in the present invention, it is preferable to provide a region where the antireflection film is not provided on the outer peripheral portion of the lens element to increase the contact area between the adhesive and the glass.

Next, the lens apparatus of the present invention will be described with reference to FIG. FIG. 5 shows only the lens barrel and the compound lens that constitute the lens device of the present invention. The compound lens shown in FIG. 1 is used as the compound lens, and the compound lens is located inside the lens barrel. Compound lenses are
From the first lens 11 side to the inside of the lens barrel 28, the first lens 1
1 is inserted until the peripheral portion of the front surface 13 contacts the rear surface 30 of the positioning step portion 29.

In the lens device of the present invention, only the side surface of any one of the lens elements constituting the compound lens needs to be in contact with the inner wall of the lens barrel. In the example of FIG. 5, the outer diameter of the first lens 11 is smaller than the outer diameter of the second lens 12, as can be seen from the example of FIG. Therefore, only the side surface 27 of the second lens 12 contacts the inner wall of the lens barrel 28, and the side surface 22 of the first lens 11 does not contact the inner wall of the lens barrel 28.

As described above, when a compound lens in which the outer diameter of one lens element is smaller than the outer diameter of the other lens element is used, only the side surface of one lens element is brought into contact with the inner wall of the lens barrel. become. Therefore, when trying to reduce the eccentricity of the entire lens device, in order to tighten the fitting tolerance between the second lens 12 and the lens barrel 28, the outer diameter tolerance of the second lens 12 in contact with the lens barrel 28 is reduced. Although it is necessary to make it strict, the outer diameter tolerance of the first lens 11 not in contact with the lens barrel 28 can be made very loose, so that the cost of the first lens 11 can be reduced.

Note that the outer diameter and the outer diameter tolerance of the first lens 11 are the same as those of the first lens 11 when the compound lens is completed.
May be determined so as not to protrude from the edge of the second lens 12. This is because if the edge of the first lens 11 protrudes from the edge of the second lens 12, the compound lens cannot be inserted into the lens barrel 28.

Also, the eccentricity between the first lens 11 and the second lens 12 has been made very small in advance, so that even if the compound lens is inserted into the lens barrel, the eccentricity between the first lens 11 and the second lens 12 will not increase. Since the eccentricity between them remains small,
Only the fitting tolerance of the portion of the lens barrel 28 that contacts the side surface 27 of the second lens 12 may be strict. Therefore, for example, even when the lens barrel 28 is manufactured by molding plastic with good mass productivity, the yield is improved because there are few portions where the dimensional tolerance of the lens barrel 28 is strict, and thereby the lens barrel 28 is improved.
Can be reduced, and the cost of the lens device can be reduced.

In general, in order to reduce unnecessary light, it is preferable to provide a light absorbing film on a part or all of a surface which does not constitute an effective area such as a side surface of a lens element. In some cases, eccentricity may occur in the lens element disposed in the lens barrel due to an error in thickness or uneven thickness. for that reason,
In a conventional lens device, when it is desired to reduce the eccentricity of the lens surface in the lens barrel, a light absorbing film is not provided or the thickness of the light absorbing film is made extremely thin. But,
In this case, there may be a problem that the unnecessary light is insufficiently reduced or the cost is increased.

On the other hand, in the case of the lens apparatus of the present invention, as shown in the example of FIG. 5, the side of one lens element can be prevented from contacting the inside of the lens barrel. An absorbing film can be provided. Therefore, unnecessary light can be reduced as compared with the related art, and cost can be reduced. If necessary, a thin light absorbing film can be provided on the side surface of the lens element that comes into contact with the inside of the lens barrel. In the lens device of the present invention, the light absorbing film may be attached after the adhesive is cured.

As described above, according to the first embodiment of the present invention, it is possible to manufacture a compound lens having excellent aberration correction and extremely small eccentricity when a lens device is configured.
Furthermore, if the compound lens of the present invention is used as a lens in a portion of a lens device having a strict eccentricity tolerance, a low-cost and high-resolution lens device can be realized.

(Embodiment 2) Next, a compound lens, a method of manufacturing a compound lens, and a lens device according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view illustrating a compound lens according to Embodiment 2 of the present invention.

As shown in the example of FIG. 6, similarly to the compound lens according to the first embodiment, the compound lens according to the second embodiment of the present invention has two opposed lens elements (31, 3).
2) That is, a first lens element (hereinafter, referred to as an object from the object side)
It is called "first lens". ) 31 and a second lens element (hereinafter, referred to as a “second lens”) 32.

Also in the compound lens according to the second embodiment shown in the example of FIG. 6, the facing surface (rear surface 34) of the first lens 31 facing the second lens 32 has a concave surface including an effective area (lens surface). 37. Further, the first lens has a plane 38 outside the concave surface 37 and perpendicular to the optical axis. In the example of FIG. 6, a conical surface 39 having a vertex on the second lens 32 side is further formed outside a plane 38 formed on the first lens 31. Front surface 33 of first lens 31
Are formed with a convex surface having a central portion as an effective region and an outer peripheral portion as a region outside the effective region. The first lens 31 is a negative meniscus lens.

In the example shown in FIG. 6, the second lens 32 has a concave surface 41 including an effective area and a vertical surface perpendicular to the optical axis on the facing surface (front surface 35) facing the first lens 31 similarly to the first lens 31. A flat surface 42. Further, a conical surface 43 having a vertex on the first lens 31 side is formed outside the plane 42 similarly to the first lens 31. On the rear surface 36 of the second lens 32, similarly to the front surface 35, a concave surface, a plane perpendicular to the optical axis, and a conical surface are formed in order from the center to the outside. The second lens is a biconcave lens. In addition, the concave surface 37,
In 41, the diameter of the effective area (effective diameter) is slightly smaller than the diameter of the concave surface (edge diameter) (see Table 3 described later).

In the example of FIG. 6, the effective area of the front surface 33 and the rear surface 34 of the first lens 31 and the second lens 32
The effective area of the rear surface 36 is a spherical surface. On the other hand, the effective area of the front surface 35 of the second lens 32 is aspheric. Both the first lens 31 and the second lens 32 are made of optical glass. In the present embodiment, the effective area of the rear surface 34 of the first lens 31 can be aspheric.

In the example of FIG. 6, the first lens 31 has a concave surface 37.
Outside, that is, in contact with the second lens 32 at the plane 38, the plane 38 and the plane 42 formed on the second lens 32 are bonded, and the first lens 31 and the second lens 32 are fixed. You. In the example of FIG. 6, the first lens 31 and the second lens 32 are considered to be not in strict contact with each other because an adhesive is interposed between the plane 38 and the plane 42. The "contact" in the invention includes such a state.

An effective reflection area is provided on the front and rear surfaces (33, 34, 35, 36) of the two lens elements (31, 32). Further, a light absorbing film is provided on the side surface 46 of the first lens 31 and the side surface 47 of the second lens 32. Table 3 shows the numerical data of the complex lens shown in FIG. 6, and Table 4 shows the aspherical data. The definition of the aspheric surface is
Is the same as

[0076]

[Table 3]

[0077]

[Table 4]

As described above, also in the compound lens according to the present embodiment, it can be said that the degree of freedom in designing for aberration correction is higher than that in the case of the conventional compound lens formed by cementing.
Therefore, even when the lens device is configured using the compound lens according to the present embodiment, the aberration of the entire lens device can be favorably corrected. In addition, since the lens units are integrated with a small eccentricity before being incorporated into the lens barrel, a reduction in resolution due to the eccentricity of the entire lens device can be suppressed.

The compound lens according to the second embodiment of the present invention shown in FIG. 6 is manufactured by the following steps (1) to (3). (1) First, a plane (38 or 42) formed on at least one of the first lens 31 and the second lens 32
Is applied, and the two lens elements (31, 32) are brought into contact so that the plane 38 and the plane 42 overlap. (2) Adjust the positional relationship so that the eccentricity between the lens elements (31, 32) in the contact state is reduced. (3) The adhesive is cured.

In the above manufacturing process, the application of the adhesive
For example, this can be performed by disposing the first lens 31 on a fixed base with the rear surface 34 facing up, and applying an ultraviolet curable resin to the flat surface 38 of the rear surface 34 in a ring shape. Also, in the above-described manufacturing process, the centering means such as a bell clamp device similar to that shown in FIG. 4 can be used for adjusting the positional relationship. First lens 3 superimposed
The first and second lenses 32 are sandwiched between two cylindrical holders as in the example of FIG.

The adjustment of the positional relationship is performed by slightly shifting the position of the second lens 32 while fixing the position of the first lens 31 while applying an appropriate pressure by two cylindrical holders. Also in the above manufacturing process, an eccentricity measuring device and a lens element fine movement device can be used in order to reduce the eccentricity by adjusting the positional relationship. When the eccentricity measuring device is used, similarly to FIG. 4, the lens holder can hold the lens element on its side surface and have a window so that parallel light can pass along the center axis of the lens holder. The formed one is used. Further, as described with reference to FIG. 4, the positional relationship is adjusted using transmitted light or reflected light.

By adjusting such a positional relationship, the first
A state in which the eccentricity of the total of four surfaces of the lens 31 and the second lens 32 is small is created, and the state is maintained. When an ultraviolet curable resin is used as the adhesive, curing is performed by irradiation with ultraviolet light. By curing the adhesive, the first
A complex lens in which the lens 31 and the second lens 32 are fixed with small eccentricity is completed.

In the method of manufacturing a compound lens according to the second embodiment of the present invention, similarly to the first embodiment,
As the adhesive, in addition to the above-described ultraviolet curable resin, a heat curable resin, a resin having ultraviolet curable and heat curable, or the like can be used. Further, an adhesive obtained by mixing an ultraviolet-curable resin and a heat-curable resin and further appropriately adding a light-absorbing material can be used as the adhesive.

The area where the adhesive contacts the first lens 31 or the second lens 32 may be appropriately set in consideration of the adhesive strength and the outer diameter of the lens device. In the manufacturing method according to the second embodiment, instead of setting the contact area, the width of the adhesive applied in a ring shape may be set.

Specifically, two lens elements (31, 3
When the outer diameter of 2) is 20 mm or less, the width of the adhesive applied in a ring shape is preferably 0.3 mm to 2 mm. The width of the adhesive applied in a ring shape is 0.3
If it is narrower than 2 mm, sufficient adhesive strength cannot be obtained and 2 mm
If it is wider, the outer diameter of the compound lens becomes larger, and the outer diameter of the lens device using the compound lens becomes larger. When the outer diameter of each of the two lens elements (31, 32) is 20 mm or more, the width of the adhesive applied in a ring shape is 10% of the outer diameter of the lens element having the smaller outer diameter.
It is preferable to set the degree.

Also in the present embodiment, it is a preferable embodiment that the width of the applied adhesive is made as small as possible and the adhesive strength is secured. Therefore, the adhesive is
Alternatively, the coating is preferably performed over the entire circumference of the flat surface 42. However, the present embodiment is not limited to this, as long as necessary adhesive strength can be secured.
It may be applied to a part of the plane 38 or the plane 42, preferably at least three parts.

The adhesive is applied to the plane 38 of the first lens 31.
And / or when applied to the flat surface 42 of the second lens 32, an excessive amount of the adhesive 45 protrudes into the effective area of the lens element and blocks an effective light beam, so that the amount of the adhesive needs to be minimized. There is. For this reason, when applying the adhesive,
It is a preferable embodiment to use an automatic discharge device configured to discharge the adhesive by a constant amount at a constant speed while making the discharge port circularly move on the plane 38 or the plane 42.

In the example shown in FIG. 6, the outer diameter of the first lens 31 is larger than the outer diameter of the second lens 32. This is because, similarly to the first embodiment, when configuring the lens device, only one side surface of the two lens elements is brought into contact with the lens barrel, and the other is not brought into contact with the lens barrel. .
For this reason, even when a lens device is configured using the compound lens according to the present embodiment, only the lens element in contact with the lens barrel needs to have a strict outer diameter tolerance, and the cost of the lens device can be reduced. it can. Further, a thicker light absorbing film can be provided on the side surface of the lens element which does not come into contact with the lens barrel, so that unnecessary light can be reduced.

In this embodiment, the lens element in contact with the lens barrel can be provided with a light absorbing film.
In this case, it is necessary to reduce the thickness of the light absorbing film, and pay attention to thickness error and uneven thickness. When eccentricity in the lens barrel becomes a problem due to a thickness error or uneven thickness of the light absorbing film, it is preferable that the light absorbing film is not provided on the side surface of the lens element that contacts the lens barrel.

As described above, according to the second embodiment of the present invention, it is possible to manufacture a compound lens having good aberration correction and a very small eccentricity when a lens device is formed.
Furthermore, if the compound lens of the present invention is used as a lens in a portion of a lens device having a strict eccentricity tolerance, a low-cost and high-resolution lens device can be realized.

(Embodiment 3) A compound lens, a method of manufacturing the compound lens, and a lens device according to Embodiment 3 of the present invention will be described with reference to FIGS. FIG.
FIG. 9 is a sectional view showing a compound lens according to a third embodiment of the present invention. In the example of FIG. 7, the compound lens is configured by three lens elements. The compound lens has a first lens element (hereinafter, referred to as a “first lens”) 5 in order from the object side.
1, a second lens element (hereinafter, referred to as “second lens”) 52, a third lens element (hereinafter, “third lens”)
That. ) 53 are overlapped.

In the example of FIG. 7, the facing surface (rear surface 55) of the second lens 52 facing the third lens 53 has a concave surface 57 including an effective area. The outside of the concave surface 57 is formed by a plane 58 perpendicular to the optical axis. Therefore, the outside of the concave surface 57 and the outside of the effective area of the third lens 53 form an annular groove surrounding the outer periphery of the compound lens.
The outer edge of the concave surface 57 becomes an edge 59, and the second lens 52 is in contact with the third lens 53 at this edge 59. Note that the front surface of the second lens 52 is formed as a concave surface having a central portion as an effective area and an outer peripheral portion as an area outside the effective area.

The front surface 56 of the third lens 53 is formed as a convex surface having a central portion as an effective region and an outer peripheral portion as a region outside the effective region. On the front surface of the third lens 53, there is an effective area inside the contact portion with the edge 59. The third lens 53 is a positive meniscus lens.

The plane 58 of the second lens 52 and the third lens 5
The cross section of the groove formed by the area outside the effective area on the front surface 66 of the third member 3 has a V-shape. This sectional shape is V
The letter-shaped groove is filled with an adhesive 61, and the second lens 52 and the third lens 53 are bonded by the adhesive 61.

As described above, the second lens 52 and the third lens 5
In the case of No. 3, similarly to the first embodiment, the opposing surface does not need to be a spherical surface having the same radius of curvature, and the degree of freedom in design for aberration correction is increased. Note that, in the compound lens according to the present embodiment, unlike the first embodiment, the first lens
The lens 51 is fixed to the second lens 52 by bonding. Both surfaces of the first lens 51 are formed as convex surfaces,
The radius of curvature of the rear surface of the first lens 51 and the radius of curvature of the front surface of the second lens 52 are the same.

In the example of FIG. 7, three lens elements (51,
52, 53) are made of optical glass. Except for the effective area of the rear surface 54 of the third lens 53 being an aspherical surface, the effective areas of the front and rear surfaces of the first to third lenses are all spherical. The absolute value of the radius of curvature of the concave surface 57 of the second lens 52 is smaller than the absolute value of the radius of curvature of the front surface 56 of the third lens 53, and air flows between the second lens 52 and the third lens 53. It is in a sealed state. On the other hand, since the first lens 51 and the second lens 52 are cemented, no air exists between them.

An anti-reflection film is provided on the effective areas of the four lens elements (51, 52, 53) in contact with air in total. Also, the side surface 6 of the first lens element 51
2. On the side surface 63 of the second lens 52, a light absorbing film is provided.

Table 5 shows the numerical data of the composite lens, and Table 6 shows the aspherical data. The definition of the aspherical surface is the same as Equation 1.

[0099]

[Table 5]

[0100]

[Table 6]

In the example of FIG. 7, the first lens 51 is formed so that its outer diameter is slightly smaller than the outer diameter of the second lens 52, and the second lens 52 has the outer diameter of the third lens 53. It is formed to be slightly smaller than the outer diameter. As described in the first embodiment, this assumes that the lens is inserted into the lens barrel from the first lens 51 side, and the peripheral portion of the front surface of the first lens 51 and the side surface 64 of the third lens 53 are connected to the lens barrel. The side surface 62 of the first lens 51 and the second lens 52
In order to prevent the side surface 63 from contacting the inner wall of the lens barrel. In this case, the outer diameter tolerance of the third lens 53 is strict, but the outer diameter tolerance of the first lens 51 and the second lens 52 can be made very loose.

The compound lens shown in the example of FIG. 7 can be manufactured by using the method for manufacturing a compound lens according to the first embodiment of the present invention. Specifically, first, the first lens 51
Alternatively, an adhesive is applied to the outer peripheral portion of one of the opposing surfaces of the second lens 52 and superposed, the positional relationship is adjusted, and the adhesive is cured. Next, the second lens to which the first lens 52 is joined
The composite lens shown in the example of FIG. 7 can be obtained by fixing the lens 52 and the third lens 53 according to the process described with reference to FIG. The above-described bell clamp device, the eccentricity measuring device and the lens element fine movement device can be used for fixing the first lens 51 and the second lens 52 and fixing the second lens 52 and the third lens 53. .

In the present embodiment, as the adhesive 61, as in Embodiments 1 and 2, an ultraviolet curable resin, a heat curable resin, a resin having ultraviolet curable and heat curable, or the like can be used. it can. Further, a mixture of an ultraviolet-curable resin and a heat-curable resin and further appropriately added with a light-absorbing material can also be used. Note that a conical surface is further provided outside the plane 58 of the second lens 52 in order to make the opening of the groove large so that the adhesive 61 can be easily filled.

Also in the compound lens according to the present embodiment, since the degree of freedom in the design for aberration correction is high on the surface facing the second lens 52 and the third lens 53, the three lens elements (51 , 52, 53) are fixed with very small eccentricity. For this reason, this compound lens has a small eccentricity even when incorporated in a lens barrel, and a lens device configured using this compound lens can satisfactorily correct aberrations of the entire device and realize a high-resolution lens device. Can be.

FIG. 8 is a sectional view showing a lens device according to Embodiment 3 of the present invention. FIG. 8 schematically illustrates the lens device, and omits a lens barrel that forms the lens device. The lens device shown in FIG.
Are incorporated. This lens device has a zoom lens composed of three lens groups. The lens groups include a first lens group 111, a second lens group
The lens group 112 and the third lens group 113 are arranged in this order.

The first lens group 111 includes first lens elements (hereinafter, referred to as “first lenses”) 11 in order from the object side.
4. Second lens element (hereinafter referred to as "second lens")
115 and a third lens element (hereinafter, referred to as “third lens”) 116.

The second lens group 112 is a fourth lens element (hereinafter, referred to as a “fourth lens”) 11 in order from the object side.
7. Fifth lens element (hereinafter referred to as “fifth lens”) 1
18. Sixth lens element (hereinafter referred to as "sixth lens")
119 and a seventh lens element (hereinafter, referred to as a “seventh lens”) 120.

Of the lens elements constituting the second lens group, a compound lens 123 constituted by combining three lens elements from a fifth lens 118 to a seventh lens 120
Is the compound lens shown in FIG. Fifth lens 118
The sixth lens 119 and the sixth lens 119 are joined, and the sixth lens 119 and the seventh lens 120 are abutted on each other and their peripheral portions are fixed with an adhesive. Of the three lens elements, the seventh lens 1
20 has the largest outer diameter. Therefore, when this compound lens is installed in the lens barrel, only the side of the seventh lens 120 contacts the inner wall of the lens barrel, and the side of the fifth lens 118 and the side of the sixth lens 119 contact the inner wall of the lens barrel. Not to be.

The third lens group 113 includes an eighth lens element (hereinafter, referred to as an “eighth lens”) 121. The object side of the second lens group 112 (the first lens group 111
An aperture 122 is arranged near (side).

Each of the first lens 114 and the second lens 115 is a negative meniscus lens having a surface with a strong curvature facing the image side, and the third lens 116 is a positive meniscus lens having a surface having a strong curvature facing the object side. . Also, the fourth lens 117,
The fifth lens 118 and the eighth lens 121 are biconvex lenses. The sixth lens 119 is a biconcave lens, the seventh lens 1
Reference numeral 20 denotes a positive meniscus lens.

The front surface (object-side surface) of the second lens 115,
The effective area on the front surface (object-side surface) of the fourth lens 117 and the rear surface (image-side surface) of the seventh lens 120 are formed as aspherical surfaces. The rear surface (image-side surface) of the fourth lens 117 is a flat surface. The effective areas of the other lens elements are all spherical.

On the image side of the third lens group 113, an optical low-pass filter 124 composed of a quartz plate is arranged, and on the image side, a solid-state image sensor 125 is arranged. An optical multilayer film that transmits visible light and reflects infrared light is deposited on the object-side surface 126 of the optical low-pass filter 124. In the solid-state imaging device 124, a cover glass 128 is provided on the object side of the imaging surface 127. The image corresponding to the object is formed by the zoom lens on the imaging surface 127 of the solid-state imaging device 125.
Formed.

First lens group 111 and second lens group 112
Is movable so as to make the focal length of the entire lens system variable. Further, the third lens group 113 is also configured to be movable for focus adjustment when the shooting distance changes. Focus adjustment when the photographing distance changes is performed by fixing the first lens group 111 and the second lens group 112 and moving the third lens group 113 in the optical axis direction. As the shooting distance becomes shorter, the third lens group 113 goes out toward the object side.

The zoom lens shown in FIG. 8 has a first lens group 111, a second lens group 112 and a third lens group when not in use.
All of the lens groups 113 can be moved toward the solid-state imaging device 125 to form a collapsed configuration. Therefore, the total optical length when not in use (the distance from the top of the front surface of the first lens 114 to the imaging surface of the solid-state imaging device) can be reduced.

In the zoom lens shown in FIG. 8, the four lens elements from the fourth lens 117 to the seventh lens 120 constituting the second lens group 112 are required to have strict eccentric tolerance. However, the three lens elements 118, 119
And 120 are integrated with little eccentricity as described in FIG. Therefore, although the deterioration of the resolution due to the eccentricity of the three lens elements is small, the resolution of the entire zoom lens is good. Further, the fourth lens 117
By performing the centering, the eccentric state of the second lens group 112 can be further reduced.

FIG. 9 is a diagram showing the configuration inside the lens barrel of the second lens group 112 shown in FIG. The compound lens 123 is a fifth lens.
The peripheral portion of the front surface of the lens 118 is
The edge 131 of the seventh lens 120.
32 is positioned by contacting the inner wall of the lens barrel 129.

Since the side surface 133 of the fifth lens 118 and the side surface 134 of the sixth lens 119 do not contact the inner wall of the lens barrel 129, the tolerance of the outer diameter of the fifth lens 118 and the sixth lens 119 can be made very small. Therefore, the fifth lens 11
The eighth and sixth lenses 119 can be manufactured at a correspondingly low cost. Since the fourth lens 117 is aligned after being set in the lens barrel, the eccentricity tolerance can be relaxed.

Thus, the second lens group 112 can be easily assembled, and the lens barrel 129 can be formed by plastic molding since the places where the processing accuracy is strict are reduced. The cost of the entire lens can be reduced. Further, the side surface 133 of the fifth lens 118 and the side surface 134 of the sixth lens 119 are
Since it does not contact the inner wall of the second lens 29, a thicker light absorbing film can be provided on all or a part of the side surface 133 of the fifth lens 118, the side surface 134 of the sixth lens 119, and the slope between them. In this case, unnecessary light can be reduced, and flare on the image plane can be reduced.

The assembly of the second lens group 112 is performed according to the following procedure. First, the compound lens 123 integrated from the image side is incorporated in the lens barrel 129, and the seventh lens 1
A small amount of adhesive is applied to three places on the inner wall of the lens barrel 129 so as to contact the outside of the effective area on the rear surface of the lens barrel 20 and the lens barrel 129, and the composite lens is fixed in the lens barrel 129 with this adhesive. I do.

Next, the fourth lens 117 is incorporated from the object side of the lens barrel 129, and the fourth lens 117 is moved slightly by using an eccentricity measuring device in the direction perpendicular to the optical axis. The 117 of the fourth lens is adjusted so that the eccentricity between the four lens elements up to the seventh lens 120 is reduced.
Adjust the position of.

At this time, since the rear surface of the fourth lens 117 is flat, even if the fourth lens 117 is slightly moved while being in contact with the lens barrel 129, the fourth lens 117 does not tilt. A small amount of adhesive is applied to three places on the inner wall of the lens barrel 129 so as to contact the front surface of the fourth lens 117 and the lens barrel 129, and the fourth lens 117 is fixed in the lens barrel 129 with this adhesive. . Therefore, the second lens group 112
, Four lens elements 117, 118, 119,
The eccentricity of each surface of 120 is very small.

As described above, the eccentricity can be sufficiently reduced by using a compound lens having small eccentricity and alignment as the second lens group 112 having a tight eccentricity tolerance. Also, three lens elements 114 and 11 constituting the first lens group 111
The eccentricity tolerances of 5 and 116 are smaller than the eccentricity tolerances of the four lens elements 117, 118, 119 and 120 of the second lens group 112, and the eccentricity tolerance of the eighth lens 121 constituting the third lens group 113 is further smaller. . Therefore, the deterioration of the imaging characteristics due to the eccentricity of the entire lens system is extremely small, and a high-resolution zoom lens can be realized. Also,
Most of the lens barrel can be made of a plastic molded product, and the cost of the lens barrel can be reduced.

It has been demanded that the total optical length of the zoom lens be shortened. For this purpose, it is only necessary to shorten the air gap as much as possible. However, since the power of each lens unit must be increased, the eccentricity tolerance and the air space tolerance of each lens element become extremely strict in order to obtain high resolution.
Therefore, as in the case of the compound lens 123 shown in FIG. 8, the positional relationship between the adjacent lens elements is adjusted so that the eccentricity is reduced, and the two lens elements are adhered at the peripheral portion. A reduction in resolution due to the eccentricity of the entire lens can be avoided, and a high-resolution zoom lens can be provided.

(Embodiment 4) A compound lens, a method of manufacturing the compound lens, and a lens device according to Embodiment 4 of the present invention will be described with reference to FIGS. FIG. 10 is a sectional view showing a compound lens according to Embodiment 4 of the present invention. In the example of FIG. 10, the compound lens is configured by three lens elements. The compound lens includes a first lens element (hereinafter, referred to as “first lens”) 71 and a second lens element (hereinafter, “second lens”) in order from the object side.
That. ) 72 and a third lens element (hereinafter, referred to as “third lens”) 73. This compound lens is configured by joining a third lens 73 to the second lens 32 of the compound lens according to the second embodiment shown in FIG.

In the example of FIG. 10, the first lens 71 and the second lens 72 are formed similarly to the example of FIG.
Is adhered on a flat surface as in the example of (1). That is, the rear surface 76 of the first lens 71 and the front surface 75 of the second lens 72 have a concave surface including an effective area and a plane perpendicular to the optical axis. The first lens 71 is a negative meniscus lens having a convex front surface 74. The second lens 72 is a biconcave lens. Third
The lens 73 is a positive meniscus lens. Second lens 7
Except for the effective area of the front surface 75 of the second surface being aspheric, the effective areas of the other surfaces are all spherical. The second lens 72
And the third lens 73 are joined, and the three lens elements 71, 72, 73 are integrated.

The front surface 74 and the rear surface 7 of the first lens 71
6, on the front surface 75 of the second lens 72 and the rear surface 77 of the third lens 73, an antireflection film is provided in each effective area.
Further, a light absorbing film is provided on the side surface 78 of the first lens 71, the side surface 79 of the second lens 72, and the side surface 80 of the third lens 73.

Table 7 shows the numerical data of the composite lens, and Table 8 shows the aspherical data. The definition of the aspherical surface is the same as Equation 1.

[0128]

[Table 7]

[0129]

[Table 8]

The compound lens shown in the example of FIG. 10 can be manufactured by using the method for manufacturing a compound lens according to the second embodiment of the present invention. Specifically, first, the second lens 7
The second lens 73 and the third lens 73 are fixed by bonding so that the eccentricity is reduced. Next, the composite lens shown in the example of FIG. 10 can be obtained by fixing the second lens 72 and the first lens 71 to which the third lens 73 is joined in accordance with the steps described in the second embodiment. . The above-mentioned bell clamp device, the eccentricity measuring device and the lens element fine movement device can be used for fixing the second lens 72 and the third lens 73 and fixing the first lens 71 and the second lens 72. .

In the present embodiment, as in the first and second embodiments, an ultraviolet-curable resin, a heat-curable resin, a resin having ultraviolet-curable and heat-curable properties can be used as the adhesive. . Further, a mixture of an ultraviolet-curable resin and a heat-curable resin and further appropriately added with a light-absorbing material can also be used.

Also in the compound lens according to the present embodiment, the degree of freedom of design for aberration correction is high on the opposing surfaces of the first lens 71 and the second lens 72. The three lens elements (71, 72, 73)
Fixed with very small eccentricity. For this reason, this compound lens has a small eccentricity even when incorporated in a lens barrel, and a lens device configured using this compound lens can satisfactorily correct aberrations of the entire device and realize a high-resolution lens device. Can be.

FIG. 11 is a sectional view showing a lens device according to Embodiment 4 of the present invention. FIG. 11 schematically illustrates the lens device, and omits a lens barrel that forms the lens device. The compound lens shown in FIG. 10 is incorporated in the lens device shown in FIG. This lens device has a zoom lens composed of four lens groups. The lens groups are arranged in this order from the object side: a first lens group 141, a second lens group 142, a third lens group 143, and a fourth lens group 144.

The first lens group 141 includes first lens elements (hereinafter referred to as “first lenses”) 14 in order from the object side.
5. Second lens element (hereinafter referred to as "second lens")
146 and a third lens element (hereinafter, referred to as “third lens”) 147.

The second lens group 142 includes a fourth lens element (hereinafter, referred to as a “fourth lens”) 14 in order from the object side.
8. Fifth lens element (hereinafter referred to as “fifth lens”) 1
49 and a sixth lens element (hereinafter referred to as “sixth lens”) 150.

The second lens group 142 is the same as the compound lens shown in FIG. Since the three lens elements 148, 149, and 150 constituting the second lens group 142 are integrated so as to reduce the eccentricity, it can be said that the deterioration of the resolution due to the eccentricity is very small. The outer diameter of the fourth lens 148 is the largest among the three lens elements. Therefore, when this compound lens is installed in the lens barrel, only the side face of the fourth lens 148 contacts the inner wall of the lens barrel, and the side face of the fifth lens 149 and the side face of the sixth lens 150 contact the inner wall of the lens barrel. Not to be.

The third lens group 143 includes, in order from the object side, a seventh lens element (hereinafter, referred to as a “seventh lens”) 151,
Eighth lens element (hereinafter, referred to as “eighth lens”) 152
And ninth lens element (hereinafter referred to as “ninth lens”)
153.

The fourth lens group 144 includes a tenth lens element (hereinafter, referred to as a “tenth lens”) 154. An optical low-pass filter 156 is arranged on the image side of the fourth lens group 144, and a solid-state image sensor 157 is arranged on the image side.
Is arranged. In the solid-state imaging device 157, a cover glass 159 is arranged on the object side of the imaging surface 158.

The first lens group 141 and the third lens group 143
Is disposed such that the position is fixed with respect to the solid-state imaging device. The zoom position can be changed by using the second lens group 14
2 is moved along the optical axis, and the fourth lens group 144 is moved along the optical axis so that the focus state on the imaging surface 158 of the solid-state image sensor 157 is optimized.

In the zoom lens shown in FIG.
Strict eccentricity tolerance is required for the lens group 142. However, the three lens elements 1 constituting the second lens group 142
48, 149 and 150 are integrated with a small eccentricity as described with reference to FIG. Further, since only the fitting tolerance between the fourth lens 148 and the lens barrel that comes into contact with the inner wall of the lens barrel needs to be strict, the second lens group 142 is held in the lens barrel with little eccentricity. That is, in the second lens group 142, the deterioration of the resolution due to the eccentricity is very small, so that the resolution of the entire lens system can be increased. Therefore, by using the lens device according to the present embodiment, a high-resolution zoom lens can be provided.

FIG. 12 is a sectional view showing a video camera using the zoom lens shown in FIG. FIG. 11 schematically shows a video camera. As shown in the example of FIG. 12, in the video camera, a small-sized video tape recorder 192 is arranged at a lower portion of a housing 191, and an imaging lens 193 is arranged at an upper front side. The zoom lens shown in FIG. 11 is used as the imaging lens 193.

On the image side of the imaging lens 193, a solid-state imaging device 194 is arranged. An optical low-pass filter 195 is arranged between the imaging lens 193 and the solid-state imaging device 194. An electronic viewfinder 196 is arranged on the upper rear side of the housing 191. The electronic viewfinder 196 includes a backlight 197 and a small liquid crystal panel 19.
8, eyepiece lens 199. Therefore, when the observer looks into the eyepiece lens 199, an enlarged virtual image of the display image on the liquid crystal panel 198 can be seen.

In the imaging lens 193, a compound lens (see FIG. 10) integrated so as to reduce the eccentricity is used as the second lens group having a tight eccentricity tolerance. Therefore, the imaging lens 193 has high resolution, and a high-resolution video camera can be provided.

(Embodiment 5) A compound lens, a method of manufacturing the compound lens, and a lens device according to Embodiment 5 of the present invention will be described with reference to FIGS.
FIG. 13 is a sectional view showing a compound lens according to Embodiment 5 of the present invention. In the example of FIG. 13, the compound lens is configured by three lens elements. The compound lens includes a first lens element (hereinafter, referred to as “first lens”) 81 and a second lens element (hereinafter, “second lens”) in order from the object side.
That. ) 82 and a third lens element (hereinafter, referred to as a “third lens”) 83 are formed so as to overlap each other.

In the example of FIG. 13, the front surface of the second lens 82 facing the first lens and the rear surface facing the third lens are the rear surface 14 of the first lens 11 shown in FIG.
And a conical surface including the effective area. The second lens 82 is a biconcave lens. Therefore, FIG.
In the compound lens shown in the example of No. 3, the contact between the first lens 81 and the second lens 82 and the contact between the second lens 82 and the third lens 8
Contact between the first lens 11 and the second lens 11 shown in the example of FIG.
The contact is performed in the same manner as the contact with the lens 12. Therefore, the parameters of the six lens surfaces can be changed independently,
The degree of freedom in designing for aberration correction is high.

Note that the first lens 81 and the third lens 83 are biconvex lenses. Each lens element (81, 82, 8
On the front surface and the rear surface of 3), an antireflection film is provided in an effective area. Side surface 86 of first lens 81 and second lens 82
A light absorbing film is provided on a side surface 87 of the light emitting device.

Table 9 shows the numerical data of the compound lens, and Table 10 shows the aspherical data. The definition of the aspherical surface is the same as Equation 1.

[0148]

[Table 9]

[0149]

[Table 10]

The compound lens shown in the example of FIG. 13 can be manufactured by using the method for manufacturing a compound lens according to the first embodiment of the present invention. Specifically, first, the first lens 8
The first and second lenses 82 are fixed by adjusting the positional relationship, filling the adhesive 85, and curing the adhesive in accordance with the steps described with reference to FIG. Next, the second lens 81 to which the first lens 81 is fixed is attached.
By fixing the lens 82 and the third lens 83 in the same manner, the composite lens shown in the example of FIG. 13 can be obtained. Here, the first lens 81 and the second lens 82 are fixed,
For fixing the second lens 82 and the third lens 83, the above-mentioned bell clamp device, an eccentricity measuring device and a lens element fine movement device can be used.

In the present embodiment, as in the first and second embodiments, an ultraviolet-curable resin, a heat-curable resin, a resin having ultraviolet-curable and heat-curable properties can be used as the adhesive. . Further, a mixture of an ultraviolet-curable resin and a heat-curable resin and further appropriately added with a light-absorbing material can also be used.

In this way, it is possible to manufacture a three-lens composite lens with good aberration correction and very small eccentricity. If this compound lens is used as a lens in a portion of the lens device where the eccentricity tolerance is strict, a high-resolution lens device with good aberration correction can be realized.

FIG. 14 is a sectional view showing a lens device according to the fifth embodiment of the present invention. FIG. 14 schematically illustrates the lens device, and omits a lens barrel that constitutes the lens device. The lens device shown in FIG. 14 incorporates the compound lens according to the fifth embodiment.

This lens device has an imaging lens composed of seven lens elements. The lens elements include a first lens element (hereinafter, referred to as “first lens”) 91 and a second lens element (hereinafter, “second lens”) from the object side.
That. ) 92, a third lens element (hereinafter, referred to as “third lens”) 93, and a fourth lens element (hereinafter, “first lens”).
Lens. " ) 94, a fifth lens element (hereinafter, referred to as a fifth lens element)
This is called the "fifth lens." ) 95, a sixth lens element (hereinafter referred to as “sixth lens”) 96, and a seventh lens element (hereinafter referred to as “seventh lens”) 97.

In the example of FIG. 14, the compound lens including the fourth lens 94, the fifth lens 95, and the sixth lens 96 is the same as the compound lens shown in FIG. The outer diameter of the sixth lens 96 is the largest among the three lens elements. Therefore, when this compound lens is installed in the lens barrel, only the side of the sixth lens 96 contacts the inner wall of the lens barrel, and the side of the fourth lens 94 and the side of the fifth lens 95 contact the inner wall of the lens barrel. Not to be.

The first lens 91 and the second lens 92 are negative meniscus lenses having convex surfaces facing the object side. The third lens 93 and the seventh lens 97 are biconvex lenses. The effective area of the front surface 99 of the fourth lens 94 and the effective area of the rear surface 100 of the sixth lens 96 are formed as aspheric surfaces. The effective areas of the other lens elements are all spherical.

An aperture 98 is arranged in a space between the third lens 93 and the fourth lens 94. On the image side of the seventh lens 97, an optical low-pass filter 102 formed by bonding a plurality of quartz plates is arranged, and further on the image side, a solid-state imaging device 103 is arranged. An optical multilayer film that transmits visible light and reflects infrared light is deposited on the object-side surface 104 of the optical low-pass filter 102. A cover glass 106 is provided on the object side of the imaging surface 105 of the solid-state imaging device 103. An image corresponding to the object is formed on the imaging surface 105 of the solid-state imaging device 103 by the imaging lens.

In the focus adjustment, the position from the third lens 93 to the seventh lens 97 is fixed with respect to the solid-state imaging device 103, and the first lens 91 and the second lens 92 are integrated with each other in the optical axis direction. It is performed by moving to.

A compound lens (lens group 10) including a fourth lens 94, a fifth lens 95, and a sixth lens 96.
1) is disposed in a portion where the eccentricity tolerance is severe in the lens device. However, the lens group 101 is integrated with a very small eccentricity, and the outer diameter tolerance of only the sixth lens 96 that contacts the inner wall of the lens barrel needs to be strict. It is held with little eccentricity. That is, in the lens group 101, the deterioration of the resolution due to the eccentricity is very small, so that the resolution of the entire lens system can be increased. In this way, a high-resolution imaging lens can be provided by integrally using a plurality of lens elements so as to minimize eccentricity in a portion where eccentricity tolerance is severe.

FIG. 15 is a sectional view showing an electronic still camera using the imaging lens shown in FIG. FIG. 15 schematically shows the electronic still camera. As shown in the example of FIG. 15, in the electronic still camera, an imaging lens 172 is arranged on the front side of a housing 171. This imaging lens 1
Reference numeral 72 denotes the same imaging lens as that shown in FIG.

On the image side of the imaging lens 172, a solid-state imaging device 173 is arranged. An optical low-pass filter 174 is arranged between the imaging lens 172 and the solid-state imaging device 173. A liquid crystal monitor 175 is provided on the rear side of the housing 171.
Is arranged. Solid-state image sensor 173 and liquid crystal monitor 1
75 is close.

In the imaging lens 172, the first lens 9
The first and second lenses 92 are incorporated in the front lens barrel 176,
From the third lens 93 to the seventh lens 97, the rear barrel 17
7 is incorporated. The solid-state imaging device 173 is attached to the rear end of the rear barrel 177. The front barrel 176 is configured to be movable along two guide poles 178 (the other one is not shown).

In the imaging lens 172, the fourth lens 94, the fifth lens 95, and the sixth
Since the lens 96 is integrated so as to reduce the eccentricity, the imaging lens 172 has a high resolution. For this reason, a high-resolution and compact electronic still camera can be realized.

As the imaging lens, the zoom lens shown in FIG. 8 can be used. Also in this zoom lens, since a compound lens which is adjusted to reduce the eccentricity and is integrated so as to reduce the eccentricity is used for a part of the second lens group 112 requiring a strict eccentricity tolerance, the electronic still is used. The camera has a higher resolution. In this case, when not in use, the total optical length can be shortened by collapsing. Therefore, an electronic still camera with high resolution and a compact camera body when not in use can be realized.

FIG. 16 is a sectional view showing a projection type display device using the imaging lens shown in FIG. In FIG. 16, reference numeral 222 denotes a lamp, and 223 denotes a concave mirror. 230 and 231 are dichroic mirrors. 229, 2
32, 236 and 238 are plane mirrors. 23
3, 234 and 239 are field lenses. 2
35 and 237 are relay lenses. 240, 24
1, 242, 246, 247 and 248 are polarizing plates. 243, 244 and 245 are liquid crystal panels.
249 is a color combining prism, and 256 is a projection lens.
As the projection lens 256, a lens having a longer back focus by modifying the imaging lens shown in FIG. 10 is used.

The light source 221 includes a lamp 222 and a concave mirror 22.
3. It is composed of a front glass plate 224. Lamp 22
Reference numeral 2 denotes an ultra-high pressure mercury lamp that emits light containing red, green, and blue color components. The concave mirror 223 is an ellipsoidal mirror, and is formed by evaporating an optical multilayer film that reflects visible light and transmits infrared light on the inner surface 226 by making the inner surface 226 of the glass base 225 a spheroidal surface. is there.

The lamp 222 is integrated with the concave mirror 223 such that the center of the illuminant is located at the first focal point of the concave mirror.
The light is reflected at 23 and proceeds to form a luminous body image at the second focal point. The front glass plate 224 is configured such that an optical multilayer film that transmits visible light and reflects infrared light and ultraviolet light is deposited on an incident surface 227 and an antireflection film is deposited on an emission surface 228. It was done. The front glass plate 224 is a concave mirror 2
The infrared light and the ultraviolet light are removed from the light emitted from 23.

The light emitted from the concave mirror 223 is reflected by the plane mirror 229 and then enters the blue transmission dichroic mirror 230, where blue light is transmitted and red light and green light are reflected. The red light and the green light are incident on the green reflecting dichroic mirror 231, the red light is transmitted, and the green light is reflected. The blue light is reflected by the plane mirror 232 and enters the field lens 233. The green light directly enters the field lens 234. Red light is the first relay lens 23
5, the light passes through the plane mirror 236, the second relay lens 237, and the plane mirror 238 in order, and enters the field lens 239.

Each field lens 233, 234, 23
9 are incident on the incident side polarizing plates 240 and 24, respectively.
1 and 242 and the corresponding liquid crystal panels 243 and 2
44 and 245. Field lens 233, 2
Reference numerals 34 and 239 are used to make the principal ray incident on the peripheral pixels of the liquid crystal panels 243, 244 and 245 perpendicular to the liquid crystal layer. Liquid crystal panels 243, 244, 24
5, an optical image is formed as a change in optical rotation according to the video signal.

Light emitted from the liquid crystal panels 243, 244, 245 passes through the output side polarizing plates 246, 247, 248 and enters the color combining prism 249. The color synthesizing prism 249 is provided with a red reflection dichroic multilayer film and a blue reflection dichroic multilayer film on each slope of the four right-angle prisms so that the red reflection dichroic multilayer film and the blue reflection dichroic multilayer film intersect in an X-shape. It is configured by joining two right angle prisms. Color synthesis prism 249
Are combined into one light by the red reflection dichroic multilayer film and the blue reflection dichroic multilayer film, and the combined light is incident on the projection lens 256.

Thus, the three liquid crystal panels 243, 24
The optical images formed on the images 4 and 245 are converted into images having a change in luminance, and are enlarged and projected by a projection lens 256 on a screen which is arranged at a distance therefrom.

In order to reduce the size and increase the resolution of the projection display device, liquid crystal panels 243, 244, and 245 are required.
It is necessary to reduce the screen size and increase the number of pixels, and it is necessary to use a high-resolution projection lens 256. That is, it is necessary to use a projection lens 256 having a very tight eccentricity tolerance.

Therefore, in the example of FIG. 16, the image pickup lens shown in FIG. 14 (the compound lens which is aligned and integrated so as to reduce the eccentricity, is used in a portion where strict eccentricity tolerance is required) Lens) is used as a projection lens. Thus, the projection display apparatus shown in FIG. 16 can obtain a high-resolution projected image.

In the example shown in FIG. 16, a projection type display device using a transmissive liquid crystal panel as the light valve device has been described. However, a reflection type liquid crystal panel, a light valve in which minute mirrors with variable tilt angles are two-dimensionally arranged, etc. Alternatively, a device that forms an optical image as a change in optical characteristics according to a video signal can be used.

As described above, the compound lens of the present invention is used as an imaging lens,
The case where the present invention is used for a projection lens has been described. However, the compound lens of the present invention can be applied to any lens apparatus for the purpose of image formation. Further, a lens device using the compound lens of the present invention can be used as long as it is an optical device using a lens device for imaging.

[0176]

As described above, according to the present invention, a compound lens with small eccentricity can be provided. By using this compound lens, a lens device such as a high-resolution imaging lens or a high-resolution projection lens can be provided. Can be provided. Also, by using a high-resolution lens device incorporating this compound lens, a high-resolution electronic still camera,
A high-resolution video camera or a high-resolution projection display device can also be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a compound lens according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating eccentricity of a lens element.

FIG. 3 is a schematic diagram illustrating eccentricity of a lens element group.

FIG. 4 is a cross-sectional view showing the method of manufacturing the compound lens according to the first embodiment of the present invention.

FIG. 5 is a sectional view showing the lens device according to the first embodiment of the present invention;

FIG. 6 is a sectional view showing a compound lens according to a second embodiment of the present invention.

FIG. 7 is a sectional view showing a compound lens according to a third embodiment of the present invention.

FIG. 8 is a sectional view illustrating a lens device according to a third embodiment of the present invention;

FIG. 9 is a diagram showing a configuration inside a lens barrel of a second lens group 112 shown in FIG.

FIG. 10 is a sectional view showing a compound lens according to a fourth embodiment of the present invention.

FIG. 11 is a sectional view illustrating a lens device according to a fourth embodiment of the present invention.

12 is a sectional view showing a video camera using the zoom lens shown in FIG.

FIG. 13 is a sectional view showing a compound lens according to a fifth embodiment of the present invention.

FIG. 14 is a sectional view schematically showing a lens device according to a fifth embodiment of the present invention.

FIG. 15 is a sectional view showing an electronic still camera using the imaging lens shown in FIG.

16 is a cross-sectional view illustrating a configuration of a projection display device using the imaging lens illustrated in FIG.

[Explanation of symbols]

11, 31 first lens 12, 32 second lens 21, 45, 61 adhesive 23, 48 light absorbing film 24 bell clamp device 28 lens barrel 51, 71, 81 first lens 52, 72, 82 second lens 53, 73, 83 Third lens 91 to 97 Lens element 98 Aperture 111 First lens group 112 Second lens group 113 Third lens group 114 to 121 Lens element 122 Aperture 123 Composite lens 124 Optical low-pass filter 125 Solid-state image sensor 129 Lens tube 141 First lens group 142 Second lens group 143 Third lens group 144 Fourth lens group 145 to 154 Lens element 161 Aperture 162, 174, 194 Optical low-pass filter 163, 173, 193 Solid-state imaging device 171, 191 Housing 172, 192 Imaging lens 175 LCD monitor 195 Electronic camera -Finder 196 Liquid crystal panel 197 Eyepiece lens 222 Lamp 223 Concave mirror 230,231 Dichroic mirror 229,232,236,238 Planar mirror 233,234,239 Field lens 235,237 Relay lens 240,241,242,246,247,248 Polarizing plate 243, 244, 245 Liquid crystal panel 249 Color combining prism 256 Projection lens

Claims (8)

[Claims] 1. A compound lens having at least a first lens element and a second lens element, wherein the first lens element has a concave surface including an effective area on an opposing surface facing the second lens element. A composite lens, wherein the composite lens is in contact with a second lens element at an outer edge of the concave surface or outside the concave surface, and is fixed to the second lens element outside the concave surface. 2. An opposing surface of the second lens element is formed as a convex surface having a central portion as an effective area and an outer peripheral area as an area outside the effective area, and the outside of the concave surface in the first lens element is a cone. The outside of the concave surface of the first lens element and the outside of the effective area of the second lens element constitute an annular groove surrounding the outer periphery of the compound lens. 2. The compound lens according to claim 1, wherein said groove is filled with an adhesive. 3. The second lens element has a concave surface including an effective area on a facing surface and a plane perpendicular to an optical axis, and the first lens element has a concave surface outside the concave surface and perpendicular to the optical axis. The compound lens according to claim 1, further comprising a flat surface, and the flat surface is bonded to the flat surface of the second lens element. 4. The composite lens according to claim 2, wherein the adhesive contains a light absorbing material. 5. The light-absorbing film formed of a light-absorbing material is provided on a part or all of a surface of at least one lens element that does not constitute an effective area. The compound lens as described. 6. The method of manufacturing a compound lens according to claim 2, wherein the first lens element is brought into contact with the second lens element at an outer edge of a concave surface, and between the lens elements in a contact state. A method of manufacturing a compound lens, comprising: at least a step of adjusting a positional relationship so as to reduce the eccentricity, and a step of filling the groove with an adhesive and curing the adhesive. 7. The method for manufacturing a compound lens according to claim 3, wherein an adhesive is applied to at least one of the first lens element and the second lens element, and the adhesive is applied to the plane. Contacting the first lens element and the second lens element such that the planes overlap;
A method of manufacturing a compound lens, comprising: at least a step of adjusting a positional relationship so as to reduce eccentricity between lens elements in a contact state, and a step of curing the adhesive. 8. A lens device comprising at least the compound lens according to claim 1 and a lens barrel configured to be able to arrange the compound lens therein, wherein the compound lens A lens device wherein the lens is disposed inside the lens barrel such that only a side surface of any one of the lens elements constituting the lens is in contact with an inner wall of the lens barrel.