Finder device

Abstract

To provide a finder device with which it is possible to dust-proof the display surface of a display element and mitigate the impact exercised on an optical system by heat generated from the display element.SOLUTION: An EVF 1 comprises: a display element 10; an optical system 20 that has a first lens group G1 and a second lens group G2 that are arranged in order beginning from the display element 10 side; a first holding frame 30 that holds the display element 10 and the first lens group G1 and seals a clearance between the display element 10 and the first lens group G1; a second holding frame that holds the second lens group G2; and a diopter adjustment unit 50 that integrally moves the display element 10 and the first lens group G1 to the second lens group G2 and adjusts diopter.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a finder device, and more particularly to an electronic finder device having a function of adjusting the diopter.

Background Art

[0002] Patent Document 1 describes a technique for shortening the overall length by disposing a concave lens between a display unit and an eyepiece unit in a finder having the display unit and the eyepiece unit. Patent Document 1 also describes that the image display surface of the display unit is dust-proofed by sealing the display unit with the concave lens.

[0003] Patent Document 2 describes a finder including a liquid crystal display, a magnifying lens that magnifies an image displayed on the liquid crystal display, and a lens for diopter adjustment.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

[0005] One embodiment according to the technology of the present disclosure provides a finder device that can prevent dust from the display surface of a display element and reduce the influence of heat generated from the display element on an optical system.

Means for Solving the Problems

[0006] (1) A viewfinder device comprising: a display element; an optical system having at least a first lens group and a second lens group in order from the display element side; a first lens group holding member that holds the first lens group and seals the space between the display element and the first lens group; a second lens group holding member that holds the second lens group; and a diopter adjustment unit that adjusts the diopter by integrally moving the display element and the first lens group with respect to the second lens group.

[0007] (2) The finder device of (1), wherein the first lens group holding member and the second lens group holding member are thermally separated.

[0008] (3) The finder device of (2), wherein the first lens group holding member and the second lens group holding member are spatially and thermally separated.

[0009] (4) The first lens group is one of the viewfinder devices (1) to (3) such that the lens closest to the display element satisfies the following condition.

[0010] 0.1 < |dL1 - dL1H| × ρ1 / OH8 < 1 however, dL1: Thickness of the lens along the optical axis OH8: 40% of the maximum length of the image display area of ​​the display element. dL1H: Thickness in the optical axis direction at height OH8 from the optical axis of the lens. ρ1: Coefficient of linear expansion of the lens (10 -5 / K) (5) The first lens group is one of the viewfinder devices (1) to (4) that satisfies the following condition.

[0011] 0.001 < |f20 - f40| / fe < 0.05 however, f20: Focal length of the first lens group at a temperature of 20 degrees Celsius f40: Focal length of the first lens group at a temperature of 40 degrees Celsius fe: Combined focal length of the first and second lens groups at a temperature of 20 degrees and a diopter of -1 dpt. (6) The first lens group is a finder device according to any one of (1) to (5) that satisfies the following conditional expression.

[0012] 0.15 < doL1 / fe < 0.4 However, doL1: The distance on the optical axis from the display surface of the display element to the vertex of the surface of the first lens group on the display element side (7) The finder device according to any one of (1) to (6) further includes a heat dissipation member that contacts the display element within the movable range of the display element and dissipates the heat of the display element.

[0013] (8) The finder device of (7), where the heat dissipation member satisfies the following conditional expression.

[0014] jA > 200 However, jA: The thermal conductivity of the heat dissipation member (9) The finder device of (7) or (8), where the heat dissipation member is formed of a flexible belt-like body and one end is connected to the display element.

[0015] (10) The finder device of (9), where the heat dissipation member is provided on a flexible printed board connected to the display element.

[0016] (11) The finder device according to any one of (1) to (10), where the member interposed between the display element and the first lens group satisfies the following conditional expression.

[0017] jFave < 0.5 However, jFave: The average value of the thermal conductivity of the member interposed between the display element and the first lens group (12) The finder device according to any one of (1) to (11), where the display element is held by the first lens group holding member.

[0018] (13) The finder device of (12), where the diopter adjustment unit moves the first lens group holding member with respect to the second lens group holding member to adjust the diopter.

[0019] (14) The viewfinder device of (13), wherein the diopter adjustment unit includes a guide unit that guides the movement of the first lens group holding member, and the guide unit is provided on the second lens group holding member. [Brief explanation of the drawing]

[0020] [Figure 1] Cross-sectional view showing one embodiment of an EVF to which the present invention is applied. [Figure 2] A diagram showing an example of an optical system. [Modes for carrying out the invention]

[0021] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0022] [composition] This section will explain the application of the present invention to an electronic viewfinder (EVF) of a digital camera (for example, a mirrorless camera). An EVF is an example of a viewfinder device.

[0023] Figure 1 is a cross-sectional view showing one embodiment of an EVF to which the present invention is applied.

[0024] For the sake of clarity, in the following explanation, the left side of Figure 1 will be considered the front of the EVF1, and the right side of Figure 1 will be considered the rear of the EVF1, thus distinguishing their directions.

[0025] As shown in the figure, the EVF1 of this embodiment includes a display element 10 for displaying an image, an optical system 20 for magnifying and observing the image displayed on the display element 10, and a diopter adjustment unit 50 for adjusting the diopter.

[0026] The display element 10 is composed of, for example, an organic light-emitting diode (OLED) display. In addition to OLED, the display element 10 can also use a liquid crystal display (LCD) or the like.

[0027] In Figure 1, the strip-shaped member indicated by reference numeral 12 is a flexible printed circuit board (FPC) extending from the display element 10. As will be described later, in the EVF1 of this embodiment, the display element 10 moves when the diopter is adjusted. For this reason, the display element 10 is connected to the control board (main board, etc.) of the digital camera via the flexible FPC 12.

[0028] In this embodiment, an FPC 12 equipped with a graphite sheet 13 is used. The graphite sheet 13 is made by processing graphite into a sheet and has high thermal conductivity (approximately 230-400 [W / mk]). By using an FPC 12 equipped with a graphite sheet 13, heat generated from the display element 10 can be guided to the FPC 12 side. In other words, the FPC 12 can function as a heat sink. In this embodiment, a flexible strip-shaped graphite sheet 13 is laminated and arranged on one side of the FPC 12. The graphite sheet 13 is an example of a heat dissipation member composed of a flexible strip-shaped body.

[0029] FPC12 is, for example, composed of a single-sided FPC. That is, it has a structure in which a conductive metal such as copper foil is bonded to one side of a base film (for example, polyimide).

[0030] The tip of the FPC12 is fixed to a bracket14 provided on the camera body. In this embodiment, the bracket14 is made of metal, for example, a copper plate.

[0031] The optical system 20 includes a first lens group G1 and a second lens group G2, arranged sequentially along the optical axis Z from the side (front side) of the display element 10. The first lens group G1 and the second lens group G2 are each composed of at least one lens. The optical elements constituting the first lens group G1 and the second lens group G2 may include lenses that have substantially no refractive power. They may also include optical elements other than lenses, such as apertures, filters, and cover glass. As an example, in this embodiment, the first lens group G1 is composed of one lens, and the second lens group G2 is composed of multiple lenses. In Figure 1, for convenience, the second lens group G2 is represented as one lens. The material of the lenses is not particularly limited. As an example, in this embodiment, resin lenses, for example, polycarbonate (PC) lenses (PC lenses) are used.

[0032] In this embodiment, the EVF1 adjusts the diopter by integrally moving the display element 10 and the first lens group G1 along the optical axis Z relative to the second lens group G2. For this reason, the first lens group G1 and the second lens group G2 are each held in different retaining frames. That is, they are held in spatially separated retaining frames. Specifically, the first lens group G1 is held in the first retaining frame 30 together with the display element 10, and the second lens group G2 is held alone in the second retaining frame 40. In this embodiment, the first retaining frame 30 is an example of a first lens group retaining member, and the second retaining frame 40 is an example of a second lens group retaining member of the second retaining member.

[0033] The first retaining frame 30 has a partition wall 31 inside. The first retaining frame 30 has a display element holding section 32 on the front side that holds the display element 10, and a first lens group holding section 33 on the rear side that holds the first lens group G1, with the partition wall 31 in between.

[0034] The partition wall 31 has a frame-like shape with an open central section and is positioned perpendicular to the optical axis Z. The front end face 31F and the rear end face 31R of the partition wall 31 are each composed of surfaces perpendicular to the optical axis Z.

[0035] The display element holding portion 32 is configured as a recess into which the display element 10 is fitted. The display element 10 is positioned and attached to the first holding frame 30 by fitting it into the display element holding portion 32. The display element 10 is mounted on the frame 11 and assembled to the first holding frame 30. The display element 10 is fixed to the first holding frame 30 by fixing the frame 11 to the first holding frame 30 with screws (not shown). The display element 10 is also adhered to the front end face 31F of the partition wall 31 via double-sided tape 34F. More specifically, double-sided tape 34F is applied along the periphery, and the display element 10 is adhered to the front end face 31F of the partition wall 31 via the double-sided tape 34F.

[0036] The first lens group holder portion 33 is configured as a recess into which the first lens group G1 is fitted. The first lens group G1 is positioned and attached to the first retaining frame 30 by fitting it into the first lens group holder portion 33. The first lens group G1 is adhered to the partition wall 31 via double-sided tape 34R. More specifically, the double-sided tape 34R is applied along the periphery and adhered to the end face of the partition wall 31.

[0037] As described above, the display element 10 and the first lens group G1 are assembled to the first retaining frame 30, thereby sealing the space between the display element 10 and the first lens group G1. This prevents dust from reaching the image display surface of the display element 10. Note that "sealing" here refers to a level where dust cannot pass through, but molecular-level transmission of oxygen and other particles is permitted.

[0038] In this embodiment, the first retaining frame 30 is made of resin, for example, glass fiber reinforced PC (for example, PC containing 30% glass fiber). The frame 11 is made of metal, for example, stainless steel (for example, SUS304). The base materials of the double-sided tapes 34F and 34R are made of resin, for example, polyethylene terephthalate (PET).

[0039] The second retaining frame 40 positions and holds the second lens group G2 on its inner circumference. The second retaining frame 40 is made of resin, similar to the first retaining frame 30, and is composed of, for example, glass fiber reinforced PC (PC with 30% glass fiber).

[0040] The diopter adjustment unit 50 adjusts the diopter by integrally moving the display element 10 and the first lens group G1 along the optical axis Z relative to the second lens group G2. As described above, in the EVF1 of this embodiment, the second lens group G2 is held in the second retaining frame 40, and the display element 10 and the first lens group G1 are held in the first retaining frame 30. Therefore, in the EVF1 of this embodiment, the diopter adjustment unit 50 adjusts the diopter by moving the first retaining frame 30 along the optical axis Z relative to the second retaining frame 40.

[0041] As shown in Figure 1, the diopter adjustment unit 50 includes a guide unit 51 that guides the movement of the first retaining frame 30 and a drive unit 52 that moves the first retaining frame 30.

[0042] The guide section 51 includes a guide rod 51A and a sliding section 51B that slides along the guide rod 51A.

[0043] The guide rod 51A is supported at one end by an axial support portion 41 provided on the second retaining frame 40 and is positioned parallel to the optical axis Z. In this embodiment, the guide rod 51A is made of metal, for example, stainless steel (SUS304 as an example).

[0044] The sliding portion 51B is integrally provided with the first retaining frame 30. The sliding portion 51B has a guide hole 51C through which the guide rod 51A is inserted.

[0045] The first retaining frame 30 is supported so as to be movable along the optical axis Z by the sliding portion 51B sliding along the guide rod 51A.

[0046] The drive unit 52 is composed of a so-called feed screw mechanism and includes a threaded rod 52A, a nut member 52B screw-connected to the threaded rod 52A, and a click mechanism 52C that clicks the threaded rod 52A into a stop position.

[0047] The threaded rod 52A is rotatably supported by a threaded rod support portion 42 provided on the second retaining frame 40 and is positioned parallel to the optical axis Z. A diopter adjustment dial 53 is connected to the threaded rod 52A. When the EVF1 is assembled to the camera body (not shown), part or all of the diopter adjustment dial 53 is positioned so as to be exposed on the outer surface of the camera body. The user rotates the threaded rod 52A by rotating this diopter adjustment dial 53.

[0048] The nut member 52B is held in a nut holding portion 35 provided on the first retaining frame 30 and is positioned parallel to the optical axis Z. In this embodiment, the threaded rod 52A and the nut member 52B are made of metal, for example, stainless steel (SUS304 as an example).

[0049] The click mechanism 52C is provided in the second retaining frame 40. The click mechanism 52C clicks the threaded rod 52A into place at regular rotational angle intervals. Since the click mechanism itself is a known configuration, a detailed explanation will be omitted. As an example, it consists of grooves arranged at regular angular intervals on the circumferential surface of the threaded rod 52A, a sphere that fits into the groove, and a spring that biases the sphere toward the groove.

[0050] As described above, the diopter adjustment unit 50 moves the first retaining frame 30 along the optical axis Z according to the direction and amount of rotation of the diopter adjustment dial 53. Since the diopter adjustment dial 53 rotates at constant rotational angle intervals by the click mechanism 52C, the first retaining frame 30 can be moved in constant steps.

[0051] The EVF1 of this embodiment is configured as described above. The EVF1 is assembled to the camera body by fixing the second retaining frame 40 to a fixing part of the camera body (not shown).

[0052] [Effect] In the EVF1 of this embodiment, the display element 10 and the first lens group G1 are held in the first retaining frame 30, and the image display surface of the display element 10 is sealed by the first lens group G1. This makes it possible to protect the image display surface of the display element 10 from dust.

[0053] Furthermore, in the EVF1 of this embodiment, diopter adjustment is performed by moving the display element 10 and the first lens group G1 integrally with respect to the second lens group G2. This allows the overall length of the optical system 20 to be shortened.

[0054] Furthermore, in the EVF1 of this embodiment, the first retaining frame 30 that holds the display element 10 and the first lens group G1, and the second retaining frame 40 that holds the second lens group G2 are spatially separated. This makes it difficult for heat generated from the display element 10 to be transferred to the second lens group G2. In other words, by spatially separating the first retaining frame 30 and the second retaining frame 40, thermal separation is also achieved. This makes it difficult for heat to be transferred between the first retaining frame 30 and the second retaining frame 40.

[0055] Furthermore, according to the EVF1 of this embodiment, an FPC 12 equipped with a graphite sheet 13 is connected to the back side of the display element 10 (opposite side from the optical system 20). This makes it difficult for heat generated from the display element 10 to be transferred to the optical system 20. In other words, the heat generated from the display element 10 is guided to the back side of the display element 10 by the graphite sheet 13, making it difficult for heat to be transferred to the optical system 20.

[0056] Since the graphite sheet 13 is provided on the FPC 12, it can always be in contact with the display element 10 even when the display element 10 is moving. In other words, the graphite sheet 13 can always be in contact with the display element 10 within the movable range of the display element 10. Furthermore, space saving can be achieved by integrating the graphite sheet 13 with the FPC 12. Alternatively, the graphite sheet may be attached to the display element 10 separately without integrating it with the FPC 12. In this embodiment, a graphite sheet is used as a heat dissipation member, but the material used as a heat dissipation member is not limited to this. Also, the heat dissipation member does not necessarily need to have a flexible configuration. It is sufficient if it can be in contact with the display element 10 within the movable range of the display element 10.

[0057] [Preferred configuration of each element] [Configuration of the first lens group] [First lens group] (1)|dL1-dL1H|×ρ1 / OH8 In the first lens group G1, it is preferable that the lens closest to the display element satisfies the following condition.

[0058] 0.1<|dL1-dL1H|×ρ1 / OH8<1…Conditional expression (1) However, dL1 is the thickness of the lens along the optical axis, OH8 is 40% of the maximum length of the image display area of ​​the display element 10 (so-called 80% object height), dL1H is the thickness in the optical axis direction at height OH8 from the optical axis of the lens, and ρ1 is the linear expansion coefficient of the lens (10 -5 It is / K).

[0059] By setting the value of |dL1-dL1H|×ρ1 / OH8 to a value greater than the lower limit of the above conditional equation, an appropriate aberration correction effect can be applied to the first lens group G1, and aberration fluctuations during diopter adjustment can be suppressed. Conversely, by setting it to a value less than the upper limit, aberration fluctuations due to temperature changes can be suppressed.

[0060] When the lens constituting the first lens group G1 is one, it is required that the lens satisfies the above conditional expression.

[0061] (2)|f20 - f40| The first lens group G1 preferably satisfies the following conditional expression.

[0062] 0.001 < |f20 - f40| / fe < 0.05... Conditional expression (2) However, f20 is the focal length of the first lens group G1 at a temperature of 20 degrees, f40 is the focal length of the first lens group G1 at a temperature of 40 degrees, and fe is the combined focal length of the first lens group G1 and the second lens group G2 in the case of a temperature of 20 degrees and a diopter of -1 dpt.

[0063] By making the value of |f20 - f40| larger than the lower limit of the above conditional expression, an appropriate refractive power can be given to the first lens group G1, and the overall length of the optical system 20 can be shortened. Also, by making it smaller than the upper limit, the change in diopter when the temperature changes can be suppressed.

[0064] (3)doL1 / fe The first lens group G1 preferably satisfies the following conditional expression.

[0065] 0.15 < doL1 / fe < 0.4... Conditional expression (3) However, doL1 is the distance on the optical axis from the image display surface of the display element 10 to the vertex of the surface of the first lens group G1 on the display element side.

[0066] By making the value of doL1 / fe larger than the lower limit of the above conditional expression, heat from the display element 10 can be made less likely to be transmitted to the first lens group G1. Also, by making it smaller than the upper limit, the overall length of the optical system 20 can be shortened.

[0067] [Heat dissipation member] The heat dissipation member that contacts the display element 10 and dissipates the heat of the display element 10 preferably satisfies the following conditional expression.

[0068] jA>200(W / mk)…Conditional expression (4) However, jA is the thermal conductivity of the heat dissipation material.

[0069] By satisfying this condition, heat from the display element 10 can be more easily transferred to the heat dissipation member. In addition, this makes it more difficult for heat to be transferred to the optical system 20.

[0070] [First Holding Slot] It is preferable that the member interposed between the display element 10 and the first lens group G1 satisfies the following condition.

[0071] jFave<0.5(W / mk)…conditional expression (5) However, jFave is the average value of the thermal conductivity of the material interposed between the display element 10 and the first lens group G1. In the EVF1 of the above embodiment, the material interposed between the display element 10 and the first lens group G1 is the partition wall 31 and the double-sided tapes 34F and 34R.

[0072] If the members interposed between the display element 10 and the first lens group G1 are denoted as E1, E2, ..., Ei from front to back, and their thickness in the optical axis direction is d1, d2, ..., di, and their thermal conductivity is j1, j2, ..., ji, then the average value of the thermal conductivity, jFave, is calculated by the following formula.

[0073] jFave={Σ(ji*di)} / dAll i = 1, 2, 3, ... However, dAll is the sum of the thicknesses in the optical axis direction of the material interposed between the display element 10 and the first lens group G1 (dAll = d1 + d2 + ... + di).

[0074] By satisfying this condition, it becomes more difficult to transfer heat from the display element 10 to the first lens group G1.

[0075] In the EVF1 of the above embodiment, if the thickness of the double-sided tape 34F on the front side of the partition wall 31 is d1, the thickness of the partition wall 31 is d2, the thickness of the double-sided tape 34R on the rear side of the partition wall 31 is d3, the thermal conductivity of the double-sided tape 34F on the front side of the partition wall 31 is j1, the thermal conductivity of the partition wall 31 is j2, and the thermal conductivity of the double-sided tape 34R on the rear side of the partition wall 31 is j3, then the average value of the thermal conductivity jFave is calculated by the following formula.

[0076] jFave=(j1*d1+j2*d2+j3*d3) / (d1+d2+d3) [Examples] Next, we will describe a numerical example of the EVF optical system.

[0077] Figure 2 shows an example of an optical system. The figure shows the configuration of the optical system 20 in a cross-section including the optical axis. In this figure, the image display surface IP of the display element is shown as the observation object, with the left side being the observation object side (display element side) and the right side being the eye point side. Note that the eye point EP shown in this figure does not indicate size or shape, but rather indicates position in the optical axis direction.

[0078] The optical system 20 shown in the figure includes, in order from the display element side to the eye point side, an optical element PP, a first lens group G1, and a second lens group G2.

[0079] Optical component PP is a parallel plate-shaped component intended for use as a protective cover glass or various filters. Therefore, optical component PP is not an essential component, and the system can be constructed without it. The first lens group G1 consists of one lens, lens L1. The second lens group G2 consists of four lenses, lenses L2, L3, L4, and L5.

[0080] Table 1 shows the basic lens data for the optical system 20 of this embodiment, Table 2 shows the variable plane spacing, and Table 3 shows the aspherical coefficient. The basic lens data in Table 1 is for a temperature of 20°C.

[0081] In the basic lens data in Table 1, "surface number" indicates the number (i) of the optical surface when counted from the display element side, "r" indicates the radius of curvature of the i-th optical surface (i-th surface), and "d" indicates the spacing between the i-th surface and the (i+1)-th surface (surface spacing). Furthermore, "Nd" indicates the refractive index of the medium between the i-th surface and the (i+1)-th surface with respect to the d-line (wavelength λ = 587.56 nm), and "νd" indicates the Abbe number of the medium between the i-th surface and the (i+1)-th surface with respect to the d-line.

[0082] Table 1 shows the surface number and the term (EP) in the column corresponding to the surface number of the eye point EP. Furthermore, in Table 1, the sign of the radius of curvature is positive for surfaces convex towards the display element, and negative for surfaces convex towards the eye point. Table 1 also shows the optical material PP and the eye point EP.

[0083] In Table 1, the variable plane spacing during diopter adjustment is indicated using the symbol dd[ ], with the face number of the display element side of this spacing written inside the [ ] in the "plane spacing d" column. Table 2 shows the values ​​of the variable plane spacing for each diopter. In Table 2, "dpt" means diopter.

[0084] In Table 1, the surface numbers of the aspherical surfaces are marked with an asterisk (*). In the optical system 20 of this embodiment, the 3rd surface (surface number 3) to the 12th surface (surface number 12) are aspherical surfaces. For aspherical surfaces, the value of the paraxial radius of curvature is listed in the radius of curvature r column.

[0085] In Table 3, "KA" and "Am" represent the numerical values ​​of the aspheric coefficients for each aspheric surface. Note that m is an integer greater than or equal to 3 and varies depending on the surface. For example, in this embodiment, m = 4, 6, 8, ..., 20. In Table 3, "E±n" (n: integer) for the numerical values ​​of the aspheric coefficients means "×10±n". KA and Am are the aspheric coefficients in the aspheric equation expressed by the following formula.

[0086] Zd = C × h 2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+ΣAm×h m In the above equation, Zd is the aspherical depth (the length of the perpendicular from a point on the aspherical surface at height h to the plane perpendicular to the optical axis to which the aspherical vertex is tangent), h is the height (the distance from the optical axis to the lens surface), C is the reciprocal of the paraxial radius of curvature, and KA and Am are the spherical coefficients. The Σ in the above equation represents the sum with respect to m.

[0087] In each table, the unit of length is millimeters (mm). Note that since the optical system can be used with proportional magnification or reduction, other appropriate units may be used. Also, in the tables below, values ​​are rounded to a predetermined number of decimal places.

[0088] [Table 1]

[0089] [Table 2]

[0090] [Table 3] Face number 3 KA 1.0000000E+00 A4 -6.3723853E-05 A6 1.8706253E-05 A8 -3.6344236E-07 A10 4.0567640E-09 A12 -5.7017587E-11 A14 5.5768112E-13 A16 1.0549800E-15 A18 -4.8665226E-17 A20 2.0712328E-19 Face number 4 KA 1.0000000E+00 A4 -1.4778114E-05 A6 6.1960997E-06 A8 1.4761325E-07 A10 -6.7104127E-09 A12 5.7511737E-11 A14 3.0492477E-13 A16 -3.8533342E-15 A18 -3.1972708E-17 A20 3.2486176E-19 Side number 5 KA 1.0000000E+00 A4 -1.3683602E-04 A6 1.7973041E-06 A8 -3.3579624E-08 A10 -1.9202314E-11 A12 2.1245734E-12 A14 3.5775140E-14 A16 -3.7491852E-16 A18 -8.0686000E-19 A20 1.1703986E-20 Side number 6 KA 1.0000000E+00 A4 8.8979927E-04 A6 -7.3361237E-06 A8 -2.7056530E-08 A10 8.7723941E-11 A12 4.3212131E-12 A14 -4.9243044E-15 A16 -1.5183528E-16 A18 7.5391219E-19 A20 -4.0884255E-21 Side number 7 KA 1.0000000E+00 A4 6.2631914E-04 A6 -2.3247038E-06 A8 -4.9936368E-08 A10 4.0885085E-10 A12 1.2389327E-12 A14 -4.1807039E-14 A16 5.0519423E-16 A18 -3.6301207E-18 A20 3.8364461E-21 Side number 8 KA 1.0000000E+00 A4 2.6659619E-04 A6 2.7304147E-06 A8 -3.6775232E-08 A10 1.9571631E-10 A12 3.2886755E-12 A14 4.4356042E-16 A16 -5.6504501E-16 A18 -2.8418986E-19 A20 3.2355755E-20 Side number 9 KA 1.0000000E+00 A4 2.5592496E-04 A6 -3.6857306E-06 A8 -7.0849577E-09 A10 2.4234197E-10 A12 1.9641352E-12 A14 8.1833821E-15 A16 -3.8634681E-16 A18 -2.1245718E-18 A20 3.4147608E-20 Side number 10 KA 1.0000000E+00 A4 -2.8641085E-04 A6 2.8617238E-07 A8 2.5225879E-09 A10 1.6181260E-11 A12 3.0566941E-14 A14 -3.9218589E-15 A16 8.5638153E-18 A18 1.4461328E-19 A20 -5.5671986E-22 Page number 11 KA 1.0000000E+00 A4 -6.2989996E-05 A6 -1.0072725E-07 A8 2.6250221E-09 A10 1.1273716E-11 A12 -1.3963483E-13 A14 -1.9714868E-15 A16 8.5171905E-18 A18 1.2296745E-19 A20 -5.5902884E-22 Page number 12 KA 1.0000000E+00 A4 1.3298085E-05 A6 -1.7580027E-07 A8 3.4082770E-09 A10 4.1429711E-12 A12 -9.0204523E-14 A14 -2.0295079E-16 A16 -3.6404378E-18 A18 5.7178056E-20 A20 -8.9925952E-23 [Satisfaction of the condition] The optical system 20 of this embodiment satisfies the following conditions (1) to (3) when lenses L1 to L5 are composed of PC lenses.

[0091] (1) Conditional expression (1) In the optical system 20 of this embodiment, the thickness dL1 on the optical axis of the lens is 1.5999952, the value OH8 which is 40% of the maximum length of the image display area of the display element is 6.4, the thickness dL1H in the optical axis direction at the height OH8 from the optical axis of the lens is 1.5999952, and the linear expansion coefficient ρ1 of the lens is 6.6 (10 -5 / K). Therefore, |dL1 - dL1H|×ρ1 / OH8 is 0.459442695. Thus, the optical system 20 of this embodiment satisfies the condition of 0.1 < |dL1 - dL1H|×ρ1 / OH8 < 1.

[0092] (2) Conditional expression (2) In the optical system 20 of this embodiment, the focal length f20 of the first lens group at a temperature of 20 degrees is -71.956257, the focal length f40 of the first lens group at a temperature of 40 degrees is -72.202079, and the combined focal length fe of the first lens group and the second lens group in the case of a temperature of 20 degrees and a diopter of -1 dpt is 18.0304871. Therefore, |f20 - f40| / fe is 0.013633686. Thus, the optical system 20 of this embodiment satisfies the condition of 0.001 < |f20 - f40| / fe < 0.05.

[0093] (3) Conditional expression (3) In the optical system 20 of this embodiment, the distance doL1 on the optical axis from the display surface of the display element to the vertex of the surface of the first lens group on the display element side is 4.7, and the combined focal length fe of the first lens group and the second lens group in the case of a temperature of 20 degrees and a diopter of -1 dpt is 18.0304871. Therefore, doL1 / fe is 0.260669608. Thus, the optical system 20 of this embodiment satisfies 0.15 < doL1 / fe < 0.4.

[0094] Regarding the conditional expression (4), by using a graphite sheet as the exhaust heat member, the condition of jA > 200 (W / mk) can be satisfied. The thermal conductivity of the graphite sheet is approximately 230 - 400 [W / mk].[[]END]]

[0095] For condition (5), for example, if the first retaining frame 30 is made of glass fiber reinforced PC (for example, PC with 30% glass fiber) and the base materials of the double-sided tapes 34F and 34R are made of PET, then jFave will be approximately 0.19 to 0.3 (assuming the thermal conductivity of glass fiber reinforced PC is 0.3 [W] / mk], the thermal conductivity of PET is 0.2~0.3[W / (Calculated as mk). Therefore, the condition jFave < 0.5 can be satisfied.

[0096] [Differentiation] [First Holding Slot] In the EVF1 of the above embodiment, the first retaining frame 30 that holds the display element 10 and the first lens group G1 is made of a single part, but the first retaining frame 30 can also be made of multiple parts. For example, the retaining member that holds the display element 10 (display element retaining member) and the retaining member that holds the first lens group G1 (first lens group retaining member) can be made of separate parts. In this case, the two can be integrated during assembly. For example, they can be joined together by adhesive or the like to integrate them.

[0097] [Diopter adjustment unit] In the EVF1 of the above embodiment, a so-called lead screw mechanism is used as the mechanism for moving the first retaining frame 30, but the mechanism for moving the first retaining frame 30 is not limited to this. It is sufficient if the first retaining frame 30 can be moved back and forth along the optical axis Z. Furthermore, it is not limited to manual movement; a motor or the like may be used to move it.

[0098] [Finder device] In the above embodiment, the application of the present invention to the EVF of a digital camera was described as an example, but the application of the present invention is not limited to this. For example, the present invention can also be applied to video cameras and the like. Furthermore, the present invention can also be applied to so-called external viewfinders.

[0099] Although the present invention has been described above with reference to embodiments and examples, the present invention is not limited to the above embodiments and examples, and various modifications are possible. For example, the radius of curvature, interplanar spacing, refractive index, Abbe number, and aspheric coefficient of each lens are not limited to the values ​​shown in the above embodiments, but can take other values. [Explanation of Symbols]

[0100] 1. Electronic viewfinder (EVF) 10 display elements 11 frames 12 Flexible Printed Circuit Boards (FPCs) 13 Graphite Sheet 14 brackets 20 Optical system 30 First Holding Slot 31. Partition of the first retaining frame 31F Front end face of bulkhead 31R Rear end face of bulkhead 32 Display element holding part 33 First lens group holding part 34F Double-sided tape 34R Double-Sided Tape 35 Nut holding part 40 Second holding slot 41 Shaft support part 42 Screw rod support part 50 Diopter adjustment section 51 Guide section 51A Guide Rod 51B Sliding part 51C Guide hole 52 Drive unit 52A Threaded rod 52B Nut component 52C Click Mechanism 53 Diopter adjustment dial EP Eye Point G1 First Lens Group G2 Second Lens Group IP Image Display Surface L1 Lens L2 lens L3 lens L4 lens L5 lens PP optical components Z optical axis d1 Thickness of double-sided tape d2 Thickness of the partition wall d3 Thickness of double-sided tape

Claims

1. Display element and At a minimum, the optical system includes a first lens group and a second lens group, arranged in order from the display element side. A first lens group holding member that holds the first lens group and seals the space between the display element and the first lens group, A second lens group holding member that holds the second lens group, A diopter adjustment unit adjusts the diopter by integrally moving the display element and the first lens group relative to the second lens group, Equipped with, The first lens group is a viewfinder device that satisfies the following condition. 0.001<|f20-f40| / fe<0.05 however, f20: Focal length (mm) of the first lens group at a temperature of 20 degrees Celsius. f40: Focal length (mm) of the first lens group at a temperature of 40 degrees Celsius. fe: The combined focal length (mm) of the first lens group and the second lens group at a temperature of 20 degrees Celsius and a diopter of -1 dpt.

2. Display element and At a minimum, the optical system includes a first lens group and a second lens group, arranged in order from the display element side. A first lens group holding member that holds the first lens group and seals the space between the display element and the first lens group, A second lens group holding member that holds the second lens group, A diopter adjustment unit adjusts the diopter by integrally moving the display element and the first lens group relative to the second lens group, Equipped with, A finder device in which the member interposed between the display element and the first lens group satisfies the following condition. jFave < 0.5 however, jFave: The average value of the thermal conductivity (W / mk) of the material interposed between the display element and the first lens group.

3. Display element and At a minimum, the optical system includes a first lens group and a second lens group, arranged in order from the display element side. A first lens group holding member that holds the first lens group and seals the space between the display element and the first lens group, A second lens group holding member that holds the second lens group, A diopter adjustment unit adjusts the diopter by integrally moving the display element and the first lens group relative to the second lens group, A heat dissipation member that contacts the display element within the movable range of the display element and dissipates heat from the display element, Equipped with, A finder device wherein the heat dissipation member satisfies the following condition. JA>200 however, jA: Thermal conductivity (W / mk) of the heat dissipation member

4. The heat dissipation member is composed of a flexible strip-shaped body, with one end connected to the display element. Finder device according to claim 3.

5. The heat dissipation member is provided on a flexible printed circuit board connected to the display element. The finder device according to claim 4.

6. The first lens group holding member and the second lens group holding member are thermally separated. A finder device according to any one of claims 1 to 5.

7. The first lens group holding member and the second lens group holding member are spatially separated and thermally separated. Finder device according to claim 6.

8. The first lens group is a finder device according to any one of claims 1 to 7, wherein the lens closest to the display element satisfies the following condition. 0.1<|dL1-dL1H|×ρ1 / OH8<1 however, dL1: Thickness of the lens along the optical axis (mm) OH8: 40% of the maximum length of the image display area of ​​the display element (mm) dL1H: Thickness in the optical axis direction (mm) at height OH8 from the optical axis of the lens. ρ1: Coefficient of linear expansion of the lens (10 -5 / K)

9. The first lens group is a finder device according to any one of claims 1 to 8, wherein the following condition is met. 0.15<doL1 / fe<0.4 however, doL1: Distance (mm) along the optical axis from the display surface of the display element to the vertex of the display element-side surface of the first lens group. fe: The combined focal length (mm) of the first lens group and the second lens group at a temperature of 20 degrees Celsius and a diopter of -1 dpt.

10. The display element is held by the first lens group holding member. A finder device according to any one of claims 1 to 9.

11. The diopter adjustment unit adjusts the diopter by moving the first lens group holding member relative to the second lens group holding member. Finder device according to claim 10.

12. The diopter adjustment unit includes a guide unit that guides the movement of the first lens group holding member. The guide portion is provided on the second lens group holding member. Finder device according to claim 11.

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