JP2016051066A - Ocular lens and observation device including the same, and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ocular lens having high optical performance in spite of being lightweight.SOLUTION: An ocular lens comprises five or more lenses including two or more resin lenses having aspherical lens surfaces and including two or more lenses having negative refractive power. A material of a lens arranged closest to an observation side in the ocular lens is a glass material. When Rdens represents specific gravities of materials of the resin lenses, all the materials of the resin lenses included in the ocular lens satisfy a conditional expression: 0.5<Rdens<1.5.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an eyepiece and an observation apparatus and an imaging apparatus having the same, and is suitable for observing an image displayed on an image display element in an electronic viewfinder used in, for example, a video camera, a still camera, and a broadcast camera. Is.

  2. Description of the Related Art Conventionally, an electronic viewfinder used in an optical apparatus such as a video camera or a broadcast camera is provided with an eyepiece lens for magnifying and observing an image displayed on a liquid crystal screen provided in the camera.

  In recent years, there has been a demand for optical devices such as video cameras and broadcast cameras that have high optical performance and have been reduced in weight. Along with this, viewfinders and eyepieces constituting the viewfinders provided in video cameras, broadcasting cameras, and the like are also required to be lightweight and to obtain high-definition observation images.

  An eyepiece that corrects various aberrations by increasing the number of lenses constituting the eyepiece and improves optical performance is known (Patent Document 1).

  The eyepiece lens of Patent Document 1 aims to improve optical performance by forming an eyepiece lens with five or more lenses.

JP2013-45020A

  As described above, in order to obtain an eyepiece having high optical performance, it is known to form an eyepiece using five or more lenses.

  In the eyepiece lens of Patent Document 1, the optical performance is improved by using two or more lenses having an aspherical surface, but it cannot be said that the weight reduction of the eyepiece lens is sufficiently realized.

  An object of the present invention is to provide an eyepiece having high optical performance while being lightweight, and an observation apparatus and an imaging apparatus having the eyepiece.

The eyepiece of the present invention is an eyepiece having five or more lenses including two or more resin lenses having an aspherical lens surface, and is the lens arranged on the most observation side among the eyepieces. The material of Le is a glass material, and when the specific gravity of the resin lens material is Rdens, all the resin lens materials included in the eyepiece lens are:
0.5 <Rdens <1.5
The material satisfies the following conditional expression.

  According to the present invention, an eyepiece having high optical performance while being lightweight can be obtained.

1 is a cross-sectional view of an eyepiece lens according to Example 1 of the present invention. Each aberration diagram of the eyepiece of Example 1 of the present invention Sectional view of eyepiece of Example 2 of the present invention Each aberration diagram of the eyepiece of Example 2 of the present invention Lens cross-sectional view of the eyepiece of Example 3 of the present invention Each aberration diagram of the eyepiece of Example 3 of the present invention Lens cross section of the eyepiece of Example 4 of the present invention Each aberration diagram of the eyepiece lens of Example 4 of the present invention Lens cross section of the eyepiece of Example 5 of the present invention Each aberration diagram of the eyepiece lens of Example 5 of the present invention Lens cross section of the eyepiece of Example 6 of the present invention Each aberration diagram of the eyepiece lens of Example 6 of the present invention Schematic diagram of main parts of an imaging apparatus of the present invention

  Hereinafter, an eyepiece of the present invention, an observation apparatus having the same, and an imaging apparatus will be described in detail with reference to the accompanying drawings. The eyepiece of the present invention has five or more lenses including two or more resin lenses.

  FIG. 1 is a lens cross-sectional view when the diopter of the eyepiece of Example 1 is −2.0 diopter (reference state), 2.5 diopter, and −6.0 diopter. FIG. 2 is an aberration diagram of the eyepiece of Example 1 in the reference state.

  FIG. 3 is a lens cross-sectional view when the diopter of the eyepiece of Example 2 is −2.0 diopter (reference state), 2.0 diopter, and −4.0 diopter. FIG. 4 is an aberration diagram of the eyepiece of Example 2 in the reference state.

  FIG. 5 is a lens cross-sectional view when the diopter of the eyepiece of Example 3 is −2.0 diopter (reference state), 2.5 diopter, and −6.0 diopter. FIG. 6 is an aberration diagram of the eyepiece lens of Example 3 in the reference state.

  FIG. 7 is a lens cross-sectional view when the diopter of the eyepiece of Example 4 is −2.0 diopter (reference state), 2.0 diopter, and −4.0 diopter. FIG. 8 is an aberration diagram of the eyepiece of Example 4 in the reference state.

  FIG. 9 is a lens cross-sectional view when the diopter of the eyepiece lens of Example 5 is −2.0 diopter (reference state), 2.0 diopter, and −4.0 diopter. FIG. 10 is an aberration diagram of the eyepiece lens of Example 5 in the reference state.

  FIG. 11 is a lens cross-sectional view when the diopter of the eyepiece of Example 6 is −2.0 diopter (reference state), 2.0 diopter, and −4.0 diopter. FIG. 12 is an aberration diagram of the eyepiece lens of Example 6 in the reference state.

  FIG. 13 is a schematic diagram of a main part of an imaging apparatus including the eyepiece of the present invention.

  The eyepiece L of each embodiment is used for an electronic viewfinder of an imaging apparatus such as a digital camera or a video camera. In the lens cross-sectional view, the left side is the image display surface side (object side), and the right side is the observation side (eye point side). I is an image display surface of an image display element such as a liquid crystal element or an organic EL element.

  The eyepieces L of Examples 1 and 2 are, in order from the object side to the observation side, a first lens G1 having a positive refractive power, a second lens G2 having a negative refractive power, a third lens G3 having a positive refractive power, and a negative lens. A fourth lens G4 having a refractive power of 5 mm and a fifth lens G5 having a positive refractive power.

  The eyepiece L of the third embodiment includes, in order from the object side to the observation side, a first lens G1 having a negative refractive power, a second lens G2 having a positive refractive power, a third lens G3 having a positive refractive power, and a positive refraction. It comprises a fourth lens G4 having a power and a fifth lens G5 having a negative refractive power.

  The eyepiece lenses L of Examples 4 to 6 are, in order from the object side to the observation side, a first lens G1 having a positive refractive power, a second lens G2 having a negative refractive power, a third lens G3 having a positive refractive power, and a negative lens. A fourth lens G4 having a refractive power of 5, a fifth lens G5 having a positive refractive power, and a sixth lens G6 having a positive refractive power.

  EP is an eye point for the user to observe an image displayed on the display surface. A plate or the like for protecting the image display surface and the lens may be provided between the image display surface I and the lens surface on the image display surface side of the first lens G1. Further, a plate or the like for protecting the lens may be provided between the eyepiece lens L and the eye point EP. Here, the eye point EP may be moved in the optical axis direction as long as the off-axis light beam emitted from the image display surface I can pass through the pupil of the observer.

  Each aberration diagram shows the aberration that occurs in the eyepiece lens L of each example when the finder diopter is in the reference state.

  In the spherical aberration diagram, spherical aberrations with respect to d-line (wavelength 587.6 nm) and g-line (wavelength 435.8 nm) are shown. In the astigmatism diagram, S is a sagittal image plane, and M is a meridional image plane. Distortion is shown for the d-line. The chromatic aberration diagram shows the chromatic aberration at the g-line.

  In the eyepiece lens of the present invention, two or more resin lenses having an aspherical lens surface are used, so that off-axis aberrations such as distortion and curvature of field are properly corrected. Here, the resin lens means a lens using a resin material. The resin lens may be a lens made of only a resin material, or may be one in which nanoparticles such as ITO (indium tin oxide) or TiO2 (titanium oxide) are dispersed in the resin material.

  In the eyepiece lens of the present invention, the resin constituting the eyepiece lens is significantly reduced in weight by using a resin having a small specific gravity as the material of the resin lens having an aspherical lens surface.

  A resin lens can easily have an aspherical lens surface as compared with a lens using a glass material. In general, a resin material is less expensive than a glass material. Therefore, by using a resin material as a material for a lens having an aspherical surface (hereinafter referred to as an aspherical lens), manufacturing costs and material costs can be reduced.

  In general, resin materials have lower environmental resistance than glass materials. For example, since a resin material is softer than a glass material, the resin lens is easily scratched. Also, when an antireflection film such as a metal oxide is applied to the lens surface to reduce ghosts and flares, the resin material has lower adhesion than the glass material, so when the lens surface is wiped with a solvent, etc. The film is easily peeled off. Furthermore, the resin material has a large change in refractive index and shape due to temperature fluctuations and humidity fluctuations compared to glass materials, and its optical characteristics are likely to change depending on the external environment.

  Therefore, in the eyepiece lens of the present invention, the material of the lens Le arranged on the most observation side is made of a glass material, so that the optical characteristics of the eyepiece lens as a whole do not change greatly even if the external environment changes. . The lens (glass lens) using a glass material absorbs ultraviolet rays contained in sunlight, etc., thereby preventing the resin lens from being discolored by the ultraviolet rays and suppressing the deterioration of the optical characteristics of the resin lens. it can. In addition, by arranging a glass lens between the resin lens and the external environment, temperature fluctuation and humidity fluctuation of the resin lens are reduced. In this way, by arranging the resin material as far as possible from the external environment, it is possible to suppress fluctuations in the optical characteristics of the resin material with respect to the external environment.

  Further, in the eyepiece of the present invention, off-axis aberrations such as field curvature and distortion are favorably corrected by using two or more aspheric lenses.

In each example, when the specific gravity of the resin material is Rdens, the material of all the resin lenses included in the eyepiece is 0.50 <Rdens <1.50 (1)
It is a material that satisfies the following conditional expression.

  Known resin materials that satisfy the conditional expression (1) include cycloolefin resins, acrylic resins (for example, PMMA), polycarbonate resins, and polyester resins. By injection molding these resin materials, an aspherical lens can be easily produced.

  Since the specific gravity of a general glass material is about 2.5 to 5.5, the weight of the lens can be significantly reduced by using a resin material that satisfies the conditional expression (1).

  If the upper limit of conditional expression (1) is exceeded and the specific gravity of the resin material is too large, it is difficult to sufficiently reduce the weight of the eyepiece. If the lower limit of conditional expression (1) is exceeded, resin materials that can be selected as lens materials are limited, which is not preferable.

  By using at least two aspherical lenses using a resin material that satisfies the conditional expression (1) in the eyepieces of the respective examples, it is possible to obtain an eyepiece having high optical performance while being lightweight.

In each embodiment, it is preferable to set the numerical range of conditional expression (1) as follows.
0.70 <Rdens <1.40 (1a)

More preferably, the numerical range of conditional expression (1) is set as follows.
0.85 <Rdens <1.35 (1b)

  Here, in the eyepiece lens L of each embodiment, diopter adjustment can be performed by moving all the lenses integrally in the optical axis direction. By moving each lens integrally, fluctuations in coma due to diopter changes can be reduced.

  Furthermore, in each embodiment, it is more preferable to satisfy one or more of the following conditional expressions. Here, D is the total thickness on the optical axis of all lenses included in the eyepiece, dr is the total thickness on the optical axis of all resin lenses included in the eyepiece, and the resin included in the eyepiece The refractive index based on the d-line of the lens material is ndr, and the Abbe number is νdr. Further, the focal length of the resin lens included in the eyepiece lens is fr, the focal length of the entire eyepiece lens system is f, and the Abbe number is based on the d-line of the resin lens material of the negative refractive power included in the eyepiece lens. And Further, the refractive index temperature coefficient is dnr / dT based on the d-line of the resin lens material included in the eyepiece, and the refraction is based on the d-line of the material of the lens Le arranged on the most observation side of the eyepiece. Let ndE be the rate. Further, the combined focal length of the lens Le and the lens disposed adjacent to the object side of the lens Le is defined as fe2.

At this time,
0.25 <dr / D <0.95 (2)
1.55 <ndr + 0.0033 × νdr <1.80 (3)
−2.5 <f / fr <2.0 (4)
5.0 <νdrn <35.0 (5)
^{-50.0 × 10 -5 /℃<dnr/dT<-5.0×10 -5 / ℃} ... (6)
1.450 <ndE <2.100 (7)
1.60 <fe2 / D <12.00 (8)
It is preferable to satisfy one or more of the following conditional expressions.

Here, when the Abbe number νd is NF, NC, Nd for the refractive indexes of the materials for the F-line (486.1 nm), C-line (656.3 nm), and d-line (587.6 nm), respectively,
νd = (Nd−1) / (NF−NC)
It is a numerical value represented by

  Conditional expression (2) defines the ratio of the total thickness D on the optical axis of all the lenses included in the eyepiece to the total sum dr on the optical axis of all the resin lenses included in the eyepiece. It is a thing.

  When the lower limit of conditional expression (2) is exceeded and the total dr on the optical axis of the resin lens becomes too small, the thickness of the lens formed using the glass material increases, and the weight of the eyepiece increases. Since it increases, it is not preferable.

  If the total thickness dr on the optical axis of the resin lens exceeds the upper limit value of the conditional expression (2), the change in the optical characteristics due to the change in the external environment increases, and the optical performance may be deteriorated. This is not preferable.

  Conditional expression (3) defines the material of the resin lens included in the eyepiece. If the lower limit of conditional expression (3) is exceeded and the refractive index ndr of the resin material is lowered, it will be difficult to sufficiently increase the refractive power of the resin lens, and the effect of canceling aberration among the plurality of resin lenses will be sufficient. This is not preferable because it is difficult to obtain. In addition, if the curvature of the lens surface of the resin lens is increased in order to increase the refractive power of the resin lens, many high-order aberrations are not preferable.

  If the upper limit of conditional expression (3) is exceeded and the refractive index ndr of the resin material is increased, the resin material that can be selected as the lens material is limited, which is not preferable.

  Conditional expression (4) defines the ratio between the focal length f of the whole eyepiece lens system and the focal length fr of the resin lens included in the eyepiece lens.

  When the lower limit of conditional expression (4) is exceeded and the negative refractive power of the resin lens becomes too strong, the curvature of the lens surface of the resin lens becomes too large. In general, since a resin material has a lower refractive index than a glass material, it is necessary to increase the curvature of the lens surface in order to increase the refractive power of the resin lens. If the curvature of the lens surface of the resin lens becomes too large, many high-order aberrations are not preferable.

  If the upper limit of conditional expression (4) is exceeded and the positive refractive power of the resin lens becomes too strong, the curvature of the lens surface of the resin lens becomes too large. If the curvature of the lens surface of the resin lens becomes too large, many high-order aberrations are not preferable.

  Conditional expression (5) is a conditional expression that defines the Abbe number νdrn of the material of the resin lens having a negative refractive power. Chromatic aberration is favorably corrected by disposing a negative lens using a highly dispersed material in an ocular lens having a positive refractive power as a whole.

  If the Abbe number νdrn of the resin lens material having a negative refractive power exceeds the lower limit value of the conditional expression (5), the chromatic aberration is excessively corrected, which is not preferable. Moreover, since the resin material which can be selected as a lens material will be limited, it is not preferable. If the Abbe number νdrn of the resin lens material having a negative refractive power exceeds the upper limit value of the conditional expression (5), it becomes difficult to sufficiently correct chromatic aberration in the eyepiece lens, which is not preferable.

  Conditional expression (6) is a conditional expression that defines the temperature coefficient dnr / dT of the refractive index with reference to the d-line of the material of the resin lens included in the eyepiece.

  If the lower limit of conditional expression (6) is exceeded and the value of the temperature coefficient dnr / dT increases, the amount of change in the refractive index with respect to the temperature change becomes too large, and variations such as field curvature and astigmatism increase. . In addition, the diopter shift accompanying the temperature change is not preferable.

  If the value of the temperature coefficient dnr / dT becomes smaller than the upper limit value of conditional expression (6), resin materials that can be selected as lens materials are limited, which is not preferable.

  Conditional expression (7) is a conditional expression that defines the refractive index ndE of the material of the lens Le arranged on the most observation side of the eyepiece.

  When the lower limit of conditional expression (7) is exceeded and the refractive index ndE of the material of the lens Le becomes too small, it is necessary to increase the curvature of the lens Le in order to ensure the refractive power of the lens Le. As a result, it is difficult to sufficiently correct spherical aberration and coma generated in the lens Le, which is not preferable.

  If the refractive index ndE of the material of the lens Le becomes too large beyond the upper limit value of the conditional expression (7), materials that can be selected as the lens material are limited, which is not preferable.

  Conditional expression (8) is the total focal length fe2 of the lens Le adjacent to the object side of the lens Le and the lens Le, and the sum D of the thicknesses on the optical axis of all the lenses included in the eyepiece. It is a conditional expression that defines the ratio.

  If the combined focal length fe2 between the lens Le adjacent to the object side of the lens Le and the lens Le becomes too short beyond the lower limit of the conditional expression (8), the refractive power of the lens arranged on the observation side Becomes too strong. As a result, the angle of the light beam passing through the peripheral part of the eyepiece lens changes greatly, and the visual field peripheral part tends to become dark with respect to the change of the eye point.

  If the combined focal length fe2 of the lens Le and the lens arranged adjacent to the object side of the lens Le becomes too long beyond the upper limit value of the conditional expression (8), the refractive power of the lens arranged on the observation side Becomes too weak. As a result, it is difficult to sufficiently correct various aberrations in the lens arranged on the observation side, which is not preferable.

It should be noted that, preferably, when the numerical ranges of conditional expressions (2) to (8) are set as follows, the effects brought about by the conditional expressions can be maximized.
0.30 <dr / D <0.93 (2a)
1.60 <ndr + 0.0033 × νdr <1.77 (3a)
−2.0 <f / fr <1.6 (4a)
15.0 <νdrn <30.0 (5a)
^{-30.0 × 10 -5 /℃<dn/dT<-7.0×10 -5 / ℃} ... (6a)
1.510 <ndE <1.950 (7a)
1.80 <fe2 / D <9.00 (8a)

More preferably, the numerical ranges of the conditional expressions (2) to (8) are set as follows.
0.35 <dr / D <0.92 (2b)
1.65 <ndr + 0.0033 × νdr <1.75 (3b)
−1.8 <f / fr <1.2 (4b)
18.0 <νdrn <28.0 (5b)
^{-20.0 × 10 -5 /℃<dn/dT<-9.0×10 -5 / ℃} ... (6b)
1.550 <ndE <1.850 (7b)
2.00 <fe2 / D <6.00 (8b)

Further, when the eyepiece lens L of each embodiment is used for an observation apparatus that observes image information displayed on the image display surface I, the following conditional expression should be satisfied.
0.50 <H / f <1.20 (9)

  Here, the diagonal length of the image display surface I is H.

  Conditional expression (9) is a conditional expression that defines the ratio of the diagonal length H of the image display surface I and the focal length f of the eyepiece.

  If the lower limit of conditional expression (9) is exceeded and the focal length f of the eyepiece becomes too long, the viewing angle becomes too narrow, which is not preferable.

  If the upper limit of conditional expression (9) is exceeded and the focal length f of the eyepiece becomes too short, the effective diameter of the lens arranged on the observation side becomes too large. As a result, in the lens arranged on the observation side, many off-axis aberrations such as coma and astigmatism occur, which is not preferable.

In each embodiment, it is preferable to set the numerical range of conditional expression (9) as follows.
0.55 <H / f <1.00 (9a)

More preferably, the numerical range of conditional expression (9) is set as follows.
0.60 <H / f <0.90 (9b)

  Next, the lens configuration of the eyepiece of each example will be described. The eyepiece of Example 1 includes, in order from the image display surface side to the observation side, a first lens G1 having a positive refractive power, a second lens G2 having a negative refractive power, a third lens G3 having a positive refractive power, and a negative lens. A fourth lens G4 having a refractive power and a fifth lens G5 having a positive refractive power are included. The second lens G2 having a negative refractive power, the third lens G3 having a positive refractive power, and the fourth lens G4 having a negative refractive power are resin lenses.

The material of the second lens G2 and the fourth lens G4 is polycarbonate resin (specific gravity 1.24, temperature coefficient of refractive index dn / dT = -12.0 × 10 ⁻⁵ , water absorption 0.35%). The material of the third lens G3 is cycloolefin resin (specific gravity 1.01, temperature coefficient of refractive index dn / dT = -11.0 × 10 ⁻⁵ , water absorption less than 0.01%). By making each lens surface of the second lens G2, the third lens G3, and the fourth lens G4 into an aspherical shape, coma, astigmatism, distortion, and the like are corrected well.

  The finder including the eyepiece of Example 1 has an image display surface diagonal length H = 18.2 mm, an eye relief of 27.0 mm, and a viewing angle of 35.0 degrees.

  The eyepiece of Example 2 has a first lens G1 having a positive refractive power, a second lens G2 having a negative refractive power, a third lens G3 having a positive refractive power, and a negative lens in order from the image display surface side to the observation side. A fourth lens G4 having a refractive power and a fifth lens G5 having a positive refractive power are included. The second lens G2 having a negative refractive power, the third lens G3 having a positive refractive power, and the fourth lens G4 having a negative refractive power are resin lenses.

The material of the second lens G2 and the fourth lens G4 is polycarbonate resin (specific gravity 1.24, temperature coefficient of refractive index dn / dT = -12.0 × 10 ⁻⁵ , water absorption 0.35%). The material of the third lens G3 is a methacrylic resin (specific gravity 1.19, temperature coefficient of refractive index dn / dT = -13.0 × 10 ⁻⁵ , water absorption 0.3%). By making each lens surface of the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, and the fifth lens G5 into an aspherical shape, coma, astigmatism, distortion, etc. are improved. It is corrected.

  The finder including the eyepiece of Example 2 has an image display surface diagonal length H = 76.2 mm, an eye relief of 27.0 mm, and a viewing angle of 45.0 degrees.

  The eyepiece of Example 3 includes, in order from the image display surface side to the observation side, a first lens G1 having a negative refractive power, a second lens G2 having a positive refractive power, a third lens G3 having a positive refractive power, and a positive lens. The lens includes a fourth lens G4 having a refractive power and a fifth lens G5 having a negative refractive power. The third lens G3 having a positive refractive power and the fourth lens G4 having a positive refractive power are resin lenses.

The material of the third lens G3 and the fourth lens G4 is a methacrylic resin (specific gravity 1.19, refractive index temperature coefficient dn / dT = -13.0 × 10 ⁻⁵ , water absorption 0.3%). By composing a part of the surface of the resin lens to be aspherical, coma, astigmatism, distortion and the like are corrected well.

  Further, by increasing the difference between the Abbe number of the material of the first lens G1 having a negative refractive power and the Abbe number of the material of the second lens G2 having a positive refractive power, axial chromatic aberration and lateral chromatic aberration are reduced. ing.

  The finder including the eyepiece of Example 3 has an image display surface diagonal length H = 32.0 mm, an eye relief of 30.0 mm, and a viewing angle of 35.0 degrees.

  The eyepiece of Example 4 includes, in order from the image display surface side to the observation side, a first lens G1 having a positive refractive power, a second lens G2 having a negative refractive power, a third lens G3 having a positive refractive power, and a negative lens. The lens includes a fourth lens G4 having a refractive power, a fifth lens G5 having a positive refractive power, and a sixth lens G6 having a positive refractive power. The first lens G1 having a positive refractive power, the second lens G2 having a negative refractive power, the third lens G3 having a positive refractive power, the fourth lens G4 having a negative refractive power, and the fifth lens G5 having a positive refractive power It is a resin lens.

The materials of the first lens group G1, the third lens G3, and the fifth lens G5 are cycloolefin resin (specific gravity 1.01, temperature coefficient of refractive index dn / dT = -11.0 × 10 ⁻⁵ , water absorption 0. Less than 01%). The material of the second lens group G2 and the fourth lens group G4 is polycarbonate resin (specific gravity 1.24, temperature coefficient of refractive index dn / dT = -12.0 × 10 ⁻⁵ , water absorption 0.35%). .

  By making each lens surface of the first lens G1, the second lens G2, the third lens G3, and the fourth lens G4 into an aspherical shape, coma, astigmatism, distortion, and the like are favorably corrected.

  In the finder including the eyepiece of Example 4, the diagonal length H of the image display surface is 38.1 mm, the eye relief is 27.0 mm, and the viewing angle is 40.0 degrees.

  In the eyepiece of Example 5, the first lens G1 having a positive refractive power, the second lens G2 having a negative refractive power, the third lens G3 having a positive refractive power, and a negative lens in order from the image display surface side to the observation side. The lens includes a fourth lens G4 having a refractive power, a fifth lens G5 having a positive refractive power, and a sixth lens G6 having a positive refractive power. The second lens G2 having a negative refractive power, the third lens G3 having a positive refractive power, and the fourth lens G4 having a negative refractive power are resin lenses.

The material of the second lens G2 and the fourth lens G4 is polycarbonate resin (specific gravity 1.24, temperature coefficient of refractive index dn / dT = -12.0 × 10 ⁻⁵ , water absorption 0.35%). The material of the third lens G3 is cycloolefin resin (specific gravity 1.01, temperature coefficient of refractive index dn / dT = -11.0 × 10 ⁻⁵ , water absorption less than 0.01%). By making each lens surface of the second lens G2, the third lens G3, and the fourth lens G4 into an aspherical shape, coma, astigmatism, distortion, and the like are corrected well.

  The finder including the eyepiece of Example 5 has an image display surface diagonal length H = 76.2 mm, an eye relief of 27.0 mm, and a viewing angle of 40.0 degrees.

  The eyepiece of Example 6 includes a first lens G1 having a positive refractive power, a second lens G2 having a negative refractive power, a third lens G3 having a positive refractive power, and a negative lens in order from the image display surface side to the observation side. The lens includes a fourth lens G4 having a refractive power, a fifth lens G5 having a positive refractive power, and a sixth lens G6 having a positive refractive power. The second lens G2 having a negative refractive power, the third lens G3 having a positive refractive power, the fourth lens G4 having a negative refractive power, and the fifth lens G5 having a positive refractive power are resin lenses.

The material of the second lens G2 and the fourth lens G4 is polycarbonate resin (specific gravity 1.24, temperature coefficient of refractive index dn / dT = -12.0 × 10 ⁻⁵ , water absorption 0.35%). The material of the third lens G3 and the fifth lens G5 is cycloolefin resin (specific gravity 1.01, temperature coefficient of refractive index dn / dT = -11.0 × 10 ⁻⁵ , water absorption less than 0.01%). . By making each lens surface of the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, and the fifth lens G5 into an aspherical shape, coma, astigmatism, distortion, etc. are improved. It is corrected.

  The finder including the eyepiece of Example 6 has an image display surface diagonal length H = 38.1 mm, an eye relief of 27.0 mm, and a viewing angle of 45.0 degrees.

  The eyepieces of Examples 1, 2, 4, 5, and 6 each have at least one resin lens having a positive refractive power and a resin lens having a negative refractive power. Thereby, aberration fluctuations and diopter shifts associated with temperature changes can be canceled satisfactorily.

  In addition, the eyepiece of each example has two or more lenses having negative refractive power. By arranging a plurality of negative lenses in an ocular lens having a positive refractive power as a whole, axial chromatic aberration and lateral chromatic aberration can be favorably corrected.

  Next, numerical examples 1 to 6 corresponding to the first to sixth embodiments of the present invention will be described. In each numerical example, i indicates the order of the optical surfaces from the image display surface side. ri is the radius of curvature of the i-th optical surface (i-th surface), di is the distance between the i-th surface and the i + 1-th surface, and ndi and νdi are the i-th optical member based on the d-line, respectively. Indicates the refractive index and Abbe number of the material. r1 represents an image display surface, and the most observation side surface represents an eye point EP.

Further, when k is an eccentricity, A4, A6, and A8 are aspherical coefficients, and the displacement in the optical axis direction at the position of the height h from the optical axis is x based on the surface vertex, the aspherical shape is
x = (h ² / R) / [1+ [1− (1 + k) (h / R) ² ] ^1/2 ] + A4h ⁴ + A6h ⁶ + A8h ⁸
Is displayed. Where R is the paraxial radius of curvature. A surface with * on the right side of the surface number indicates an aspheric surface. The display of “e-Z” means “10 ^−Z ”.

[Numerical Example 1]
Unit mm
Surface data surface number rd nd νd
1 ∞ 0.70 1.51000 60.0
2 ∞ (variable)
3 -65.737 3.95 2.00069 25.5
4 -22.170 3.52
5 * -14.334 3.00 1.63550 23.8
6 * 110.330 0.30
7 * 48.492 6.84 1.53110 55.9
8 * -21.874 1.20
9 * 128.789 1.41 1.63550 23.8
10 * 22.276 1.20
11 39.057 8.21 1.83481 42.7
12 -39.057 27.00
13 (Eyepoint)
Aspheric data 5th surface
K = -7.28787e-001 A 4 = -6.03675e-005 A 6 = 1.77471e-007
6th page
K = 4.51650e + 001 A 4 = -1.11796e-005 A 6 = -6.19143e-008
7th page
K = -4.38548e + 000 A 4 = -2.38798e-005 A 6 = -2.65742e-008
8th page
K = -1.22703e + 000 A 4 = -4.69821e-006 A 6 = 3.91413e-008
9th page
K = -2.69921e + 002 A 4 = -1.52881e-007 A 6 = -4.63945e-009
10th page
K = -4.63925e + 000 A 4 = 4.39848e-006 A 6 = 5.19693e-010
Various data diopters [diopter] -2.0 +2.5 -6.0
Focal length 28.56 28.56 28.56
d 2 9.12 12.79 5.80

[Numerical Example 2]
Unit mm
Surface data surface number rd nd νd
1 ∞ 0.70 1.51000 60.0
2 ∞ (variable)
3 * -98.827 11.19 1.85135 40.1
4 * -71.371 20.00
5 * -49.765 3.00 1.63550 23.8
6 * -407.575 1.11
7 * -1171.461 7.94 1.49171 57.4
8 * -82.367 1.20
9 * 219.883 3.76 1.63550 23.8
10 * 74.863 1.23
11 * 95.021 8.12 1.80610 40.7
12 * -92.616 27.00
13 (Eyepoint)
Aspheric data 3rd surface
K = 4.54099e-001 A 4 = 3.40725e-008 A 6 = 7.53032e-011 A 8 = -1.51639e-013
4th page
K = 3.40970e-001 A 4 = 8.48720e-008 A 6 = -4.76459e-011 A 8 = 1.79616e-014
5th page
K = 3.53841e-001
6th page
K = -1.00057e + 003
7th page
K = -2.99780e + 003 A 4 = -5.75156e-006 A 6 = 7.03535e-009
8th page
K = -1.18365e + 000 A 4 = 4.34382e-006 A 6 = -5.53385e-009
9th page
K = 1.75400e + 001 A 4 = -2.52412e-006 A 6 = -7.75632e-009
10th page
K = -1.05760e + 001 A 4 = -6.88282e-006 A 6 = 3.02568e-009
11th page
K = 3.83428e + 000
12th page
K = 1.63448e + 000
Various data diopters [diopter] -2.0 +2.0 -4.0
Focal length 91.98 91.98 91.98
d 2 31.59 66.08 20.00

[Numerical Example 3]
Unit mm
Surface data surface number rd nd νd
1 ∞ 0.70 1.51000 60.0
2 ∞ (variable)
3 -18.559 1.00 1.64769 33.8
4 405.260 8.54 1.69350 53.2
5 * -30.810 1.18
6 * 161.494 7.67 1.49171 57.4
7 -38.921 0.10
8 * 48.932 8.43 1.49171 57.4
9 -97.046 0.10
10 33.326 1.20 1.69895 30.1
11 22.887 30.00
12 (Eyepoint)
Aspheric data 5th surface
K = -6.54146e-003
6th page
K = -2.64204e + 002 A 4 = -3.16425e-006 A 6 = -2.31819e-009
8th page
K = 1.87604e + 000
Various data diopters [diopter] -2.0 +2.5 -6.0
Focal length 50.29 50.29 50.29
d 2 28.47 40.02 20.00

[Numerical Example 4]
Unit mm
Surface data surface number rd nd νd
1 ∞ 0.70 1.51000 60.0
2 ∞ (variable)
3 * 166.099 9.26 1.53110 55.9
4 * -34.164 6.60
5 * -28.931 3.82 1.63550 23.8
6 * -93.400 0.47
7 * -153.697 3.79 1.53110 55.9
8 * -50.254 2.12
9 * -40.174 6.83 1.63550 23.8
10 * -56.296 1.20
11 -3131.870 4.55 1.53110 55.9
12 -62.412 1.20
13 110.718 3.36 1.49700 81.5
14 -332.326 27.00
15 (eye point)
Aspheric data 3rd surface
K = -9.59406e + 001 A 4 = -2.43307e-006 A 6 = -5.82983e-009
4th page
K = 3.24062e-001 A 4 = 2.14830e-006 A 6 = 2.81943e-009
5th page
K = 9.32664e-002 A 4 = -5.63898e-007 A 6 = 2.57659e-008
6th page
K = -8.05489e + 000 A 4 = 6.49218e-007 A 6 = -1.63252e-010
7th page
K = -4.96939e + 001 A 4 = -1.17845e-006 A 6 = -4.58865e-009
8th page
K = 2.90402e-001 A 4 = -2.46377e-006 A 6 = 5.28440e-009
9th page
K = -1.87452e-001 A 4 = 1.66992e-006 A 6 = -7.39182e-009
10th page
K = 2.96336e + 000 A 4 = 4.16642e-007 A 6 = 1.08928e-009
Various data diopters [diopter] -2.0 +2.0 -4.0
Focal length 52.34 52.34 52.34
d 2 22.29 33.23 17.21

[Numerical Example 5]
Unit mm
Surface data surface number rd nd νd
1 ∞ 0.70 1.51000 60.0
2 ∞ (variable)
3 -1201.003 20.00 1.48749 70.2
4 -89.718 20.00
5 * -64.550 3.06 1.63550 23.8
6 * -160.023 2.00
7 * -230.109 3.54 1.53110 55.9
8 * -119.762 1.20
9 * -86.800 12.72 1.63550 23.8
10 * -103.753 1.20
11 5354.752 4.23 1.60311 60.6
12 -123.568 1.20
13 178.678 3.96 1.51633 64.1
14 -395.781 27.00
15 (eye point)
Aspheric data 5th surface
K = 2.64919e + 000 A 4 = -7.42759e-007
6th page
K = -6.77987e + 001 A 4 = -2.49183e-008
7th page
K = 6.98083e + 001 A 4 = -1.18509e-006
8th page
K = 5.02189e + 000 A 4 = -2.98254e-006 A 6 = -1.01200e-009
9th page
K = 2.92913e + 000 A 4 = 1.34769e-006
10th page
K = 1.50370e + 000 A 4 = -8.31493e-007
Various data diopters [diopter] -2.0 +2.0 -4.0
Focal length 104.68 104.68 104.68
d 2 32.12 76.83 17.13

[Numerical Example 6]
Unit mm
Surface data surface number rd nd νd
1 ∞ 0.70 1.51000 60.0
2 ∞ (variable)
3 * 136.125 8.69 1.69350 53.2
4 * -43.222 8.67
5 * -28.738 3.00 1.63550 23.8
6 * -89.027 0.30
7 * -231.429 5.74 1.53110 55.9
8 * -46.578 2.68
9 * -39.537 2.66 1.63550 23.8
10 * -55.894 1.84
11 * -2299.162 5.94 1.53110 55.9
12 * -60.213 1.20
13 110.718 4.00 1.55332 71.7
14 -332.326 27.00
15 (eye point)
Aspheric data 3rd surface
K = -6.07439e + 000 A 4 = -1.82896e-006 A 6 = -5.07089e-009
4th page
K = 5.99930e-001 A 4 = 1.41427e-006 A 6 = 4.25770e-010
5th page
K = 1.13826e-001 A 4 = -6.11987e-007 A 6 = 2.58066e-008
6th page
K = -7.86704e + 000 A 4 = 6.27492e-007 A 6 = -5.81898e-010
7th page
K = -3.07481e + 001 A 4 = -8.80513e-007 A 6 = -3.57889e-009
8th page
K = 5.53963e-001 A 4 = -2.76657e-006 A 6 = 4.45282e-009
9th page
K = -1.40844e-001 A 4 = 1.47140e-006 A 6 = -7.32877e-009
10th page
K = 3.06010e + 000 A 4 = 6.99258e-007 A 6 = 1.21727e-009
11th page
K = 1.00225e + 004 A 4 = -2.66396e-007 A 6 = 8.58565e-011 A 8 = 9.72106e-013
12th page
K = -3.51427e-001 A 4 = 2.36708e-007 A 6 = 2.33340e-010 A 8 = -4.05287e-013
Various data diopters [diopter] -2.0 +2.0 -4.0
Focal length 45.99 45.99 45.99
d 2 19.29 27.62 15.12

  Next, an embodiment of a video camera using an eyepiece as shown in each example will be described with reference to FIG.

  In FIG. 13, reference numeral 10 denotes a video camera body, 11 denotes an imaging optical system that forms a subject image on an imaging element (not shown), and 12 denotes a sound collecting microphone. Reference numeral 13 denotes an observation apparatus (electronic viewfinder) for observing a subject image displayed on an image display element (not shown) through the eyepiece of the present invention. The image display element is constituted by a liquid crystal panel or the like, and an object image or the like formed by the photographing optical system 11 is displayed on the image display element.

  Thus, by applying the eyepiece of the present invention to an imaging apparatus such as a video camera, an imaging apparatus having high optical performance while being lightweight can be obtained.

L eyepiece lens G1 first lens G2 second lens G3 third lens G4 fourth lens G5 fifth lens G6 sixth lens I image display surface EP eye point

Claims (16)

An ocular lens having five or more lenses including two or more resin lenses having an aspherical lens surface,
The material of the lens Le arranged on the most observation side among the eyepieces is a glass material,
When the specific gravity of the resin lens material is Rdens, all the resin lens materials included in the eyepiece are:
0.5 <Rdens <1.5
An eyepiece characterized by being a material that satisfies the following conditional expression:   The eyepiece according to claim 1, comprising two or more lenses having negative refractive power. When the total thickness on the optical axis of all the lenses included in the eyepiece lens is D, and the total thickness on the optical axis of all the resin lenses included in the eyepiece lens is dr,
0.25 <dr / D <0.95
The eyepiece according to claim 1, wherein the following conditional expression is satisfied. When the refractive index based on the d-line of the resin lens material included in the eyepiece is ndr and the Abbe number is νdr, all the resin lens materials included in the eyepiece are:
1.55 <ndr + 0.0033 × νdr <1.80
The eyepiece according to any one of claims 1 to 3, wherein the material satisfies a conditional expression: When the focal length of the resin lens included in the eyepiece lens is fr and the focal length of the entire eyepiece lens system is f, all the resin lenses included in the eyepiece lens are:
-2.5 <f / fr <2.0
The eyepiece according to any one of claims 1 to 4, wherein the following conditional expression is satisfied.   The eyepiece according to claim 1, comprising at least one resin lens having a positive refractive power and at least one resin lens having a negative refractive power. When a resin lens having a negative refractive power is included and the Abbe number based on the d-line of the resin lens material is νdrn,
5.0 <νdrn <35.0
The eyepiece according to claim 1, wherein the following conditional expression is satisfied. When the temperature coefficient of refractive index based on the d-line of the resin lens material included in the eyepiece lens is dnr / dT, all the resin lens materials included in the eyepiece lens are:
-50.0 × ^{10 -5} /℃<dnr/dT<-5.0×10 ^-5 / ℃
The eyepiece according to any one of claims 1 to 7, wherein the material satisfies the following conditional expression. When the refractive index based on the d-line of the material of the lens Le is ndE,
1.450 <ndE <2.100
The eyepiece lens according to claim 1, wherein the following conditional expression is satisfied. When the combined focal length of the lens Le and the lens arranged adjacent to the object side of the lens Le is fe2, and the total thickness on the optical axis of all the lenses included in the eyepiece lens is D,
1.60 <fe2 / D <12.00
The eyepiece according to claim 1, wherein the following conditional expression is satisfied.   In order from the object side to the observation side, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a negative refractive power, and a first lens having a positive refractive power. The ocular lens according to claim 1, comprising five lenses.   In order from the object side to the observation side, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a negative refractive power, and a first lens having a positive refractive power. The eyepiece according to any one of claims 1 to 10, comprising five lenses and a sixth lens having a positive refractive power.   In order from the object side to the observation side, a first lens having a negative refractive power, a second lens having a positive refractive power, a third lens having a positive refractive power, a fourth lens having a positive refractive power, and a first lens having a negative refractive power. The ocular lens according to claim 1, comprising five lenses.   The eyepiece lens according to any one of claims 1 to 13, wherein all the lenses constituting the eyepiece lens move integrally when the diopter is adjusted. An image display element that displays an image, and an observation device that observes an image displayed on the image display surface of the image display element with the eyepiece according to any one of claims 1 to 14,
When the focal length of the whole eyepiece lens system is f and the diagonal length of the image display surface is H,
0.50 <H / f <1.20
An observation apparatus that satisfies the following conditional expression: An image sensor;
An imaging optical system for forming an object image on the imaging device;
An image display element for displaying the object image;
15. An imaging apparatus comprising the eyepiece according to claim 1, which is used for observing an image displayed on the image display element.

Images