JPH08220409A - Optical instrument - Google Patents

Abstract

PURPOSE: To prevent the interval between a projection means and a light receiving means from being changed by providing the connecting part of a combining means to a frame in a position further than the light receiving means from the projection means, in an optical axial direction. CONSTITUTION: The connecting part of a second combining member 45 to a first combining member 37 is provided in the position further than an image pickup element 19 from a projection lens 11, in the direction of an optical axis O. Therefore, the directions where the first and second combining members 37 and 45 are thermally expanded are opposite with respect to the photographic lens 11. Therefore, the thermal expansion of the frame 33 and the first combining member 37 is made the same as that of the second combining member 45, so that the interval between the photographic lens 11 and the image pickup element 19 can be always kept constant regardless of a temperature and the change in the interval between the lens 11 and the image pickup element 19 caused by variations in the temperature can be prevented. Moreover, a coefficient of the thermal expansion of the second combining member 45 is larger than that of the frame 33 and the first combining member 37. Thus, a compact optical instrument can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optical devices such as cameras, electronic still cameras, video cameras and the like.

[0002]

2. Description of the Related Art Generally, in an electronic camera such as an electronic still camera or a video camera, an image pickup device for converting a subject image projected by a photographing lens into an electric video signal is arranged. Conventionally, as a mounting structure of an image sensor in such an electronic camera, for example, there is Japanese Patent Application No. 3-287042 filed previously by the present applicant.

However, when an electronic camera having such a mounting structure for an image pickup device is used outdoors, the internal temperature of the electronic camera may reach 60 ° C. or higher in the hot sun in summer. In winter, it may be below -20 ° C. In such a state, due to the thermal expansion of the housing holding the taking lens and the image sensor,
The distance between the taking lens and the image sensor may change.

For example, the taking lens and the image pickup element are 40 m apart.
It is assumed that the case is held in the case at a distance of m.
In this case, if the housing material is aluminum alloy,
The coefficient of thermal expansion of aluminum alloy is 2.3 × 10 ^-5 ,
If there is a temperature difference of ± 30 ° C., the distance between the taking lens and the image sensor is calculated to deviate by about ± 28 μm.

On the other hand, considering the position adjustment of the image sensor, when the F number of the light beam incident on the image sensor is 1.4 and the size of one pixel of the image sensor is 10 μm square,
If the positional deviation of the image sensor is not adjusted to ± 14 μm or less, the image on the image sensor will be blurred. Further, when plastic or the like is used as the material of the lens, it is conceivable that the refractive index changes due to the temperature expansion of the plastic and the image on the image pickup device is also blurred.

In order to solve such a problem, a technique of moving a part of the photographing lens in the optical axis direction with a material whose shape is largely changed by temperature is disclosed in, for example, Japanese Patent Laid-Open No. 57-2025.
No. 07, JP-A-61-270714 and the like.

[0007]

However, in such a conventional technique, since some of the plurality of lenses are designed to be movable, there are restrictions in optical design such as lack of freedom in optical design. However, there is a problem that a preferable optical design becomes difficult.

If the lens holding member is made of a material whose shape changes greatly with temperature to hold the lens, the following mechanical design problems occur. That is, for a plastic or the like having a large shape change due to temperature, the dimension when poured into a mold (in a molten state) and the dimension after cooling are significantly different, so that the dimensional accuracy of the product deteriorates.

If the lens is held by such a component having poor dimensional accuracy, the optical axis of the lens may be tilted or misaligned, so that predetermined optical performance cannot be obtained. As a way to solve this,
There is also a method of adhering the lens to the lens holding member after the adjustment so as to eliminate the above-mentioned collapse and displacement, but there is a problem that the cost increases due to the adjustment work.

Further, even if a method of holding a bimetal, which is a metal plate having a large thermal deformation, is used, the degree of thermal deformation of the bimetal is usually ± 0.1 mm in the bending accuracy in the thickness direction.
The above is the problem that it is difficult to obtain the accuracy of the optical axis of the lens as compared with the processing accuracy of ± 0.01 mm or less for brass or aluminum. The present invention has been made in order to solve such a conventional problem, and an object of the present invention is to provide an optical device capable of reliably preventing a change in the distance between the projection unit and the light receiving unit due to a temperature change. To do.

[0011]

The optical device according to claim 1 is
Case (eg, 33, 37 in FIG. 1, 85, 83 in FIG. 5)
The object image from the projection means (eg, 11 in FIG. 1) held on one side of the housing is coupled to the other side of the housing (eg,
In the optical device for projecting onto the light receiving means (for example, 19 in FIG. 1) held via 45 in FIG. 1 and 89 in FIG.
A connecting portion of the coupling means to the housing (for example, 4 in FIG. 1).
5b, 91) in FIG. 5 is provided at a position farther from the light receiving means in the optical axis (O) direction with respect to the projection means, and the thermal expansion coefficient of the coupling means is set to be smaller than that of the housing. It is characterized by being made larger.

According to a second aspect of the present invention, there is provided an optical apparatus according to the first aspect, wherein the casing is coupled with a first casing (for example, 33 in FIG. 1, 85 in FIG. 5) to which the image pickup means is connected. It is characterized in that it can be divided into a second housing (for example, 37 in FIG. 1, 83 in FIG. 5) to which the means is connected. The optical device according to claim 3 is a housing (for example, 33, 3 in FIG. 1).
7) a projection means (for example, 1 in FIG. 1) held on one side.
In an optical device for projecting a subject image from 1) onto a light receiving means held on the other side of the housing via a holding means (for example, 97 in FIG. 6), the holding means is provided on the other side of the housing. Is connected via coupling means (eg, 93 in FIG. 6), and the connection portion of the coupling means to the housing is connected to the projection means by light from the connection portion of the holding means to the coupling means. It is provided at a position distant in the axial direction, and the thermal expansion coefficient of the coupling means is larger than the thermal expansion coefficients of the casing and the holding means.

An optical apparatus according to a fourth aspect of the present invention has a projection means (eg, 1 in FIG. 6) on one side of the coupling means (eg, 93 in FIG. 6).
1) is connected, and on the other side of the coupling means, a light receiving means for receiving a subject image from the projection means via a holding means (for example, 97 in FIG. 6) is arranged, and the projection means of the projection means is arranged. Connection to coupling means (eg 95 in FIG. 6)
Is provided at a position closer to the light receiving means in the optical axis direction than a connecting portion (for example, 99 in FIG. 6) of the holding means to the coupling means, and the thermal expansion coefficient of the coupling means is set to the holding means. The thermal expansion coefficient is larger than that of

The optical device according to claim 5 is the optical device according to any one of claims 1 to 4.
In, the light receiving means is an image sensor (eg, 19)
Is characterized in that. An optical apparatus according to a sixth aspect is the optical apparatus according to any one of the first to fifth aspects, wherein the projection means is a reduction optical system (for example, 81 in FIG. 4) that reduces the subject image.

[0015]

According to the optical apparatus of the present invention, since the connecting portion of the coupling means to the housing is provided at a position farther from the light receiving means than the light receiving means with respect to the projecting means, the housing is provided with respect to the projecting means. The thermal expansion direction is opposite to the thermal expansion direction of the coupling means.

Therefore, by making the thermal expansion amount of the housing equal to the thermal expansion amount of the coupling means, the distance between the projection means and the light receiving means is always constant regardless of the temperature. Further, since the coefficient of thermal expansion of the coupling means is made larger than the coefficient of thermal expansion of the housing, the dimension of the coupling means in the optical axis direction is smaller than the dimension of the housing in the optical axis direction. In the optical device according to the second aspect, the coupling means is connected to the divided second housing.

In the optical apparatus according to the third aspect, the connecting portion of the coupling means to the housing is provided at a position farther from the projection means in the optical axis direction than the connecting portion of the holding means to the coupling means. The direction in which the housing and the holding means thermally expand with respect to the means is opposite to the direction in which the coupling means thermally expands. Therefore, by making the amount of thermal expansion of the housing and the amount of thermal expansion of the holding means the same as the amount of thermal expansion of the coupling means, the distance between the projection means and the light receiving means is related to the temperature. Not always constant.

Further, since the thermal expansion coefficient of the coupling means is made larger than the thermal expansion coefficients of the housing and the holding means, the size of the housing and the holding means in the optical axis direction are added together. In comparison, the dimension of the coupling means in the optical axis direction becomes smaller.
In the optical device according to the fourth aspect, the connecting portion of the projecting means to the connecting means is provided at a position closer to the light receiving means in the optical axis direction than the connecting portion of the holding means to the connecting means. The direction in which the holding means thermally expands is opposite to the direction in which the coupling means thermally expands.

Therefore, by making the thermal expansion amount of the holding means and the thermal expansion amount of the coupling means the same, the distance between the projection means and the light receiving means is always constant regardless of the temperature. Also,
Since the coefficient of thermal expansion of the coupling means is made larger than the coefficient of thermal expansion of the holding means, the dimension of the coupling means in the optical axis direction becomes smaller than the dimension of the holding means in the optical axis direction. In the optical device according to the fifth aspect, the light receiving means is an image pickup device.

According to another aspect of the optical apparatus, the projection means is a reduction optical system for reducing the subject image.

[0021]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a first embodiment in which the inventions of claims 1, 2 and 5 are applied to an electronic camera. In this electronic camera, a light flux from a subject image (not shown) passes through the taking lens 11, the diaphragm 13, the beam splitter 15, and the optical low-pass filter 17, and enters the image sensor 19.

A total reflection mirror 21 is provided above the beam splitter 15, and a condenser lens 23 and a photometric element 25 are provided below the beam splitter 15.
The taking lens 11 includes lenses 27 and 29 and a lens barrel 31.
Held in. The lens barrel 31 is fixed to the housing 33 with screws 35.

On the right side of the housing 33, a first connecting member 37 having a plurality of protrusions 37a is arranged. The first coupling member 37 is arranged between the fixed plate 39 and the housing 33. Further, the fixing plate 39 is formed with a screw hole 39a, and the first coupling member 37 is formed with a through hole 37b.

Then, the screw 41 from the housing 33 side is screwed into the screw hole 39a formed in the fixing plate 39, whereby the first coupling member 37 is provided between the fixing plate 39 and the housing 33. It is clamped and fixed. The through hole 37b of the first coupling member 37 through which the screw 41 penetrates has a size sufficiently larger than the diameter of the screw 41, and when the screw 41 is loose, the through hole 37b may be slightly orthogonal to the optical axis O. The amount can be moved.

The image pickup device holding member 43 is fixed to the second connecting member 45 with a screw (not shown), and an optical low pass filter 17 and a dustproof rubber are provided between the image pickup device holding member 43 and the second connecting member 45. 47, image sensor 1
9 is pinched. The second coupling member 45 is integrally provided with a plurality of cylindrical protrusions 45a, and the protrusions 37a of the first coupling member 37 are fitted to the tips thereof.

A bellows-shaped dustproof rubber 49 is provided between the housing 33 and the image pickup element holding member 43. The operation of the electronic camera of the first embodiment will be described below. In this electronic camera, the light flux A emitted from a subject (not shown) enters the taking lens 11, is focused by the diaphragm 13 to a predetermined amount, and then enters the beam splitter 15.

The beam splitter 15 reflects 5% of the luminous flux C with respect to the luminous flux A and transmits 95% of the luminous flux B.
The light flux B passes through the optical low pass filter 17 and enters the image sensor 19.

The light beam B is reflected by the image pickup device 19 and the light beam D
And enters the beam splitter 15 again. Luminous flux D
Has a light amount of about 40% of the light flux B and 38% of the light flux A. Then, a part of the light beam D is reflected downward by the beam splitter 15, and 5% of the light beam D and 2% of the light beam A enter the condensing lens 23 as a light beam E, and photometry is performed. It is incident on the element 25.

On the other hand, the light flux C is reflected by the total reflection mirror 21, and becomes a light flux F with almost no loss of light quantity and is incident on the beam splitter 15 again. 95% of the luminous flux F and 4.8% of the luminous flux A are condensed as the luminous flux G by the condenser lens 23 and enter the photometric element 25. As a result of the above, the light flux E and the light flux G are combined,
The luminous flux of 6.8% with respect to the luminous flux A is the photometric element 2
It is incident on 5.

This value is the same when the beam splitter having a reflectance of 5% is used, and the light flux A to the photometric element is the same while the amount of light incident on the image pickup element is the same.
As compared with the conventional example in which only 5% of the luminous flux is incident, it means that the amount of light incident on the photometric element 25 is increased by about 36%. In the electronic camera described above, the light fluxes C and F and the light fluxes B and D reciprocate in the same optical path, so that the light from the taking lens 11 to the photometric element 25.
It is possible to secure the required optical path length up to and to downsize the device.

As described above, the light amount control of the flash light emitting device such as a strobe is performed on the basis of the luminous flux incident on the photometric element 25. Further, the light flux incident on the image pickup element 19 is recorded on a recording medium through a signal processing circuit (not shown).

Next, the image pickup device 19 of the electronic camera described above.
The position adjustment of will be described. Generally, the image sensor 19
Must be set at a predetermined position with respect to the taking lens 11. Further, for example, the opening F of the taking lens 11
When the value is F1.4 and the pixel pitch of the image pickup element 19 is 10 μm, it must be adjusted to ± 14 μm or less in the optical axis O direction including the inclination with respect to a predetermined position.

In the direction orthogonal to the optical axis O, the optical axis O passing through the center of the taking lens 11 and the image pickup element 19
It is usually done to align with the center of. For such position adjustment, an adjusting device as shown in FIG. 2 is used. In FIG. 2, reference numeral 51 is a photographing lens holding jig having a chart 53 as a reference for adjustment.

On the chart 53, marks indicating the positions of the four corners of the screen and arrow-shaped patterns for viewing the resolutions of the four corners and the central portion are printed. Reference numeral 55 is an adjustment jig that holds the second coupling member 45, can move in the directions of the three axes orthogonal to each other, and can rotate about the three axes, with a total of six degrees of freedom. Here, the direction parallel to the optical axis O is the Z axis, and the orthogonal directions are the X and Y axes.

The rotation around the Z axis is φ, and the rotation around the X axis and the Y axis is φω. In FIG. 1, in a state where the screw 41 is loosened, the first coupling member 37, the second coupling member 45, the image sensor holding member 43, the optical low-pass filter 1 are provided by a margin of the through hole 37b with respect to the screw 41.
7. The image pickup device 19 is movable in the X and Y directions integrally, and is rotatable in the φ direction.

Further, with respect to the projection 37a of the first coupling member 37, the fitting hole 45b of the projection 45a of the second coupling member 45 is provided.
By sliding in the Z-axis direction, the second coupling member 45
The image pickup element holding member 43, the optical low-pass filter 17, and the image pickup element 19 can move in the Z-axis direction integrally with the above.

Further, a fitting hole 45b is provided for the protrusion 37a.
Is loosely fitted, so that it can be slightly rotated in the ψ and ω directions. Then, as shown in FIG. 2, in the state where the second jig 45 is held by the adjusting jig 55,
The position of the image pickup device 19 is adjusted by operating the adjusting jig 55 so that the image of the chart 53 is formed on the image pickup device 19.

Next, by tightening the screw 41 at the adjusted position, the first connecting member 37 is clamped and fixed between the housing 33 and the fixing plate 39. After this, the fitting hole 45b
And the protrusion 37a are bonded and fixed, and the position adjustment of the image sensor 19 is completed. By the way, in general, a material expands as the temperature rises and contracts as the temperature falls.

Therefore, the fitting hole 45 which is the above-mentioned adhesive portion.
The distance L1 between b and the pupil position of the taking lens 11 (here, it coincides with the position of the diaphragm 13) increases with thermal expansion. On the other hand, the distance L0 between the fitting hole 45b and the image sensor 19 also increases. In general, the package of the image pickup device 19 is made of ceramics, and the coefficient of thermal expansion of the ceramics is much smaller than that of the second connecting member 45, as described later, so that the image pickup device 19 and the second connecting member are made. Four
The distance between the joint surface 57 with 5 and the fitting hole 45b may be L0.

Here, when the average coefficient of thermal expansion of the material forming the member within the distance L1 is α1 and the coefficient of thermal expansion of the material forming the second coupling member 45 is α0, L1 × α1 = L0 × α0 By setting (1), the thermal expansion amounts of the two become equal and the deformations are canceled by each other. Therefore, L1-L0, which is the distance between the exit pupil of the taking lens 11 and the image sensor 19, can be kept constant. It will be possible.

As a result, the distance between the exit pupil position of the taking lens 11 and the image pickup device 19 can be kept constant at all times. Here, referring to specific materials of the constituent members, the casing 33 and the first coupling member 37 are made of a material having a low temperature expansion coefficient, for example, an aluminum alloy (coefficient of thermal expansion 2.3 × 10 3).
^-5 ), a polycarbonate containing a large amount of glass fibers (coefficient of thermal expansion: 1.2 × 10 ^{-5 to} 3.8 × 10 ^-5 ), an epoxy resin or a phenol resin which is a thermosetting resin containing a glass fiber ( Thermal expansion coefficient 0.8-3.5 × 10 ^-5 )
It is formed with.

It should be noted that some of the above-mentioned constituents are made of ceramics having a smaller coefficient of thermal expansion (coefficient of thermal expansion of 0.3 to 0.6).
× 10 ⁻⁵ ) may be used. On the other hand, the second coupling member 45
Is an ABS resin (coefficient of thermal expansion 8 to 11 × 10 ⁻⁵ ) or a fluororesin (coefficient of thermal expansion 7
˜14 × 10 ⁻⁵ ).

From the above materials, for example, all the constituent materials at the distance L1 are made of aluminum alloy (coefficient of thermal expansion 2.3 × 10 ⁻⁵ ).
And the second coupling member 45 forming the distance L0 is
When it is formed of S resin (11 × 10 ⁻⁵ ), L0 may be L0 = 2.3 / 11 × L1 = 0.21 × L1-(2).

Further, when the constituent material contained in the distance of L1 is polycarbonate, it may be about L0 = 1.2 / 11 × L1 = 0.1 × L1-(3). Further, when the casing 33 and the first coupling member 37 are made of ceramic (coefficient of thermal expansion 0.3 to 0.6 × 10 ⁻⁵ ), which is included in the distance L1, the length of L0 is further increased. Can be shortened.

Regarding the above dimensions, the taking lens 1
Although the deviation of the focal position due to the temperature expansion of the glass No. 1 was ignored, if the deviation of the imaging position due to the thermal expansion can be measured experimentally, the length of L0 can be determined including the value. That is, if the image forming position of the photographing lens 11 is displaced leftward by the length P1 per unit temperature, L0 may be determined so as to satisfy L1 × α1 + P1 = L0 × α0-(4).

By the way, generally, a resin part using a material having a large coefficient of thermal expansion is largely deformed between a molten state and a solidified state at the time of molding, and the dimensional accuracy of the part is deteriorated. However, in the configuration of the present invention, even if the dimensional accuracy of the second coupling member 45 is poor, the position adjustment is performed when the image pickup device 19 is attached, so that an error in the dimensional accuracy can be absorbed and the dimensional accuracy can be reduced. Variations are not an assembly issue.

Since the projections 37a and the projections 45a are provided equidistantly and symmetrically with respect to the optical axis O,
Deformation due to thermal expansion in the direction orthogonal to the optical axis O is canceled out, and the center of the image sensor 19 does not move with respect to the optical axis O. By the way, the coefficient of thermal expansion of the resin slightly changes depending on the direction of the molten metal flow at the time of molding the resin, and especially in the case of containing glass fiber, the coefficient of thermal expansion is small in the direction along the flow and is orthogonal to the molten metal flow. In the direction, the coefficient of thermal expansion is relatively large.

Therefore, in practice, it is difficult to set the coefficient of thermal expansion that strictly satisfies the expression (1). In order to deal with such a problem, it is possible to absorb the error in the coefficient of thermal expansion by keeping the image sensor 19 within a range that does not affect the image quality even if the position of the image sensor 19 shifts at the highest temperature or the lowest temperature. is there.

Here, the pixel size of the image pickup device 19 is set to N.
mm, F number of incident light flux is F, and it can be used in the range of normal temperature (20 ° C) to ± T ° C. Then, even if the position of the image pickup device 19 is moved by F × N mm, the image quality is not affected.

This is because, depending on the size of the pixel, blur cannot be detected on the image sensor 19 even if the image is blurred. When the formula (4) is converted into a form considering this allowable value, T × (L1 × α1 + P1-L0 × α0) <F × N --- (5), and α1 and α0 and L0 satisfy the formula.
Should be decided.

In the electronic camera of the first embodiment described above,
Since the connection portion of the second coupling member 45 to the first coupling member 37 is provided at a position farther from the image pickup device 19 in the optical axis O direction with respect to the taking lens 11, the first taking member 11 with respect to the taking lens 11.
The direction in which the coupling member 37 thermally expands is opposite to the direction in which the second coupling member 45 thermally expands. Therefore, the housing 33
And the amount of thermal expansion of the first coupling member 37 and the second coupling member 45.
By setting the same thermal expansion amount, the distance between the taking lens 11 and the image sensor 19 is always constant regardless of the temperature, and the distance between the taking lens 11 and the image sensor 19 changes due to temperature change. It can be surely prevented.

As a result, the image forming position of the taking lens 11 is changed to
The position of the image sensor 19 can always be matched. Further, since the coefficient of thermal expansion of the second coupling member 45 is set to be larger than the coefficient of thermal expansion of the housing 33 and the first coupling member 37, compared with the dimensions of the housing 33 and the first coupling member 37 in the optical axis O direction. The size of the second coupling member 45 in the optical axis O direction is reduced, and a compact optical device can be obtained.

Further, in the electronic camera described above, the housing 3
The second coupling member 4 to the first coupling member 37 that can be separated from
Since 5 is connected, the position adjustment of the taking lens 11 and the image pickup device 19 becomes easy. In addition, the image sensor 19
As a result, the subject image from the taking lens 11 can be reliably converted into an electrical video signal.

In the electronic camera described above, even if there is a member having poor dimensional accuracy due to a large thermal expansion coefficient in a part of the holding mechanism of the image pickup element 19, the image pickup element 19 will be used.
However, since it is mounted by adjustment, deterioration of mounting accuracy can be automatically absorbed by adjustment. Further, since it is not necessary to install a temperature compensating mechanism in the holding mechanism of the taking lens 11, the mounting dimension accuracy of the taking lens 11 does not deteriorate, and the degree of freedom in optical design can be sufficiently secured.

FIG. 3 shows a second embodiment corresponding to the invention of claims 1, 2 and 5, and parts having the same functions as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. . In this embodiment, the front side of the beam splitting surface 59a of the beam splitter 59 extends upward, and a total reflection mirror 61 is formed on the upper surface of the extending portion 59b by total reflection coating.
The beam splitter 59 and the total reflection mirror 61 are integrally formed.

In this embodiment, since the beam splitter 59 and the total reflection mirror 61 are integrally formed, the number of parts can be reduced and the assemblability can be improved. FIG. 4 shows a third embodiment of the present invention corresponding to claims 1, 2, 5, and 6, parts having the same functions as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. . This third embodiment is 35 mm
Approximately 9 mm of a 36 mm × 24 mm square aerial image created on the primary image plane 65 by the taking lens 63 used for film
This is a device for reducing and projecting onto an image sensor 19 having an effective pixel size of × 7 mm and recording an image as an electrical signal.

In FIG. 4, the luminous flux condensed by the taking lens 63 is reflected upward by the 45-degree mirror 67 and focused on the focusing screen 69, and then the subject brightness is measured by the photometric optical system 71 and the finder optical system is used. The system 73 allows the subject image to be viewed by the user. On the other hand, at the time of photographing, the 45-degree mirror 67 is retracted upward, the shutter 75 is opened, the aerial image formed by the photographing lens 63 is formed on the primary image forming surface 65, and the field lens 77 provided thereafter, After passing through the relay lens 79 and the beam splitter 15, the image is made incident on the image pickup device 19 as in the first embodiment.

Although the relay lens 79 is usually composed of a plurality of lenses, it is shown as an ideal single thin lens for the sake of explanation. Also in the above-described configuration, as in the first embodiment, a part of the light flux incident on the beam splitter 15 is transmitted to the image pickup element 19, and the reflected light is reflected by the beam splitter 15 again, and the photometric element 25.
Incident on.

The rest of the light beam incident on the beam splitter 15 is reflected by the total reflection mirror 21, and the light beam reflected by the total reflection mirror 21 passes through the beam splitter 15 again and enters the photometric element 25. Therefore, as in the first embodiment, it is possible to increase the amount of light incident on the photometric element 25 without decreasing the amount of light incident on the image sensor 19.

Next, the influence of the thermal expansion of the electronic camera of the third embodiment will be described. First, the relationship between the thermal expansion between the primary imaging surface 65 and the relay lens 79 and the imaging position on the image sensor 19 will be described. The distance between the primary imaging plane 65 and the relay lens 79 is L2, the distance between the relay lens 79 and the fitting hole 45b, which is the bonding portion between the first coupling member 37 and the second coupling member 45, is L1, and the second coupling member. 45 length L0
And

The average thermal expansion coefficient of the material forming the distance L2 is α2, the average thermal expansion coefficient of the material forming L1 is α1, and the thermal expansion coefficient of the second coupling member 45 is α0. . The ratio β of the size of the image on the primary imaging plane 65 and the size of the image projected on the image pickup device 19 by the relay lens 79 is β = (L1-L0) / L2-(6). .

Here, the change amount ΔL1 of the image forming position on the image pickup device 19 when L2 changes due to thermal expansion is
By differentiating the equation (6) with respect to L2, ΔL1 = {(L1-L0) / L2} ² × α 2 × L ² = β ² × α 2 × L 2 --- (7) When L2 undergoes thermal expansion, the image forming position shifts to the left, so ΔL1 has a positive sign in the left direction.

Next, the amount of movement of the image to the left on the image pickup device 19 due to the thermal expansion of the taking lens 63 is set to P3. Regarding this value, if the focusing screen 69 and the primary imaging plane 65 are in a conjugate position with respect to the 45-degree mirror 67, and the user confirms the focus on the focusing screen 69, the primary imaging is performed. Since it is almost in focus on the surface 65, it can be almost ignored.

The amount of movement of the image on the image pickup element 19 to the left due to the thermal expansion of the field lens 77 is P2, and the amount of movement of the image to the left on the image pickup element 19 due to the thermal expansion of the relay lens 79 is P1. And Note that these values may be obtained experimentally or by numerical calculation. The length L0 required to absorb the influence of temperature expansion with respect to the above variables has a relationship of ΔL1 + L1 × α1 + P3 + P2 + P1 = L0 × α0 --- (8).

Therefore, by substituting the equation (7) into the equation (8), α2, α1, α0, and L0 are set so that α2 × L2 × β ² + L1 × α1 + P3 + P2 + P1 = L0 × α0 --- (9) Just decide. As in the case of equation (5), if there is a margin for the variation of the coefficient of thermal expansion, α2 × L2 × β ² + L1 × α1 + P3 + P2 + P1-L0 × α0 <F × N --- (10) It is only necessary to determine α2, α1, α0, and L0.

In the third embodiment, almost the same effect as in the first embodiment can be obtained, but in this embodiment, the object image formed on the primary image forming surface 65 by the taking lens 63 is The reduction optical system 81 having the field lens 77 and the relay lens 79 can further reduce the size and project the image onto the imaging element 19. FIG. 5 shows a fourth embodiment of the present invention corresponding to claims 1, 2 and 5, parts having the same functions as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, the first coupling member 83 is provided on the housing 85 via an adjustment allowance 87 formed of a gap, and an adhesive is applied to the adjustment allowance 87 after adjusting the image pickup device 19. It is designed to be filled. In addition, in this embodiment, the first coupling member 83 and the second coupling member 89 may be fixed by screwing, bonding or the like.

In this embodiment, the first connecting member 83 and the second connecting member 83
An adjustment allowance 91 is provided between the joint member 89 and the joint member 89 so that an adhesive can be filled therein. As the adhesive agent, a molten metal such as solder may be used in addition to the epoxy resin, but it is necessary to join the peripheral members while cooling them so as not to cause thermal expansion.

Also in the fourth embodiment, the amounts of thermal expansion of the housing 85 and the first connecting member 83 and the second connecting member 89.
By setting the thermal expansion coefficients of the respective members so that the thermal expansion amounts of 1 and 2 become equal, it is possible to prevent blurring of the image due to thermal expansion. Further, in this embodiment, since it is not necessary to fit the second coupling member 89 to the first coupling member 83, the degree of freedom in design can be increased accordingly.

FIG. 6 shows a fifth embodiment of the present invention corresponding to claims 4 and 5, parts having the same functions as those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. To do. In this embodiment, the lens barrel 31 holding the taking lens 11 is connected to the joining member 93 at the connecting portion 95 by adhesion.

A holding member 9 for holding the image pickup device 19
7 and the connecting member 93 are connected to each other at the connecting portion 99 by adhesion. The connecting portion 95 is located closer to the image pickup device 19 in the optical axis direction than the connecting portion 99. Further, the thermal expansion coefficient α0 of the coupling member 93 is
Is larger than the thermal expansion coefficient α1 of the lens barrel 31 and the thermal expansion coefficient α2 of the holding member 97.

Therefore, the thermal expansion amount of the distance L1 between the exit pupil position of the photographing lens 11 (equal to the position of the diaphragm 13 in this embodiment) and the connecting portion 95 and the distance L2 between the connecting portion 99 and the image pickup element 19 are set. By selecting L0 and L2 so that the thermal expansion amount including the thermal expansion amount becomes equal to the thermal expansion amount of the coupling member 93 at the distance L0, the exit pupil position and the image sensor 1 are selected.
The distance from 9 can be made constant.

In the above-mentioned embodiments, an example in which the present invention is applied to an electronic camera has been described, but the present invention is not limited to such an embodiment. For example, a camera using a film as a light receiving means or a It can be widely applied to optical devices such as steppers. In addition, the fifth described above
In the embodiment described above, the example in which the lens barrel 31 is directly connected to the coupling member 93 has been described, but the present invention is not limited to such an embodiment. For example, the lens barrel is connected to the housing and the housing is connected to the housing. You may connect a coupling member.

[0075]

As described above, in the optical device according to the first aspect, the connecting portion of the coupling means to the housing is provided at a position farther from the light receiving means than the light receiving means with respect to the projection means. The direction in which the housing thermally expands with respect to the projection means is opposite to the direction in which the coupling means thermally expands.

Therefore, by making the amount of thermal expansion of the housing equal to the amount of thermal expansion of the coupling means, the distance between the projection means and the light receiving means is always constant regardless of the temperature, and the projection means is changed by the temperature change. It is possible to reliably prevent the distance from the light receiving means from changing. As a result, the image forming position of the projection unit can be always matched with the position of the light receiving unit.

Since the coefficient of thermal expansion of the coupling means is made larger than the coefficient of thermal expansion of the housing, the dimension of the coupling means in the optical axis direction is smaller than the size of the housing in the optical axis direction, which is compact. Optical equipment can be obtained. In the optical device according to the second aspect, since the coupling means is connected to the divided second housing, it is easy to adjust the positions of the projection means and the light receiving means.

In the optical apparatus according to the third aspect, the connecting portion of the coupling means to the housing is provided at a position farther from the projection means in the optical axis direction than the connecting portion of the holding means to the coupling means. The direction in which the housing and the holding means thermally expand with respect to the means is opposite to the direction in which the coupling means thermally expands. Therefore, by making the amount of thermal expansion of the housing and the amount of thermal expansion of the holding means the same as the amount of thermal expansion of the coupling means, the distance between the projection means and the light receiving means is related to the temperature. However, it is always constant, and it is possible to reliably prevent the distance between the projection means and the light receiving means from changing due to temperature changes.

Further, since the coefficient of thermal expansion of the coupling means is made larger than the coefficients of thermal expansion of the housing and the holding means, the dimension of the housing in the optical axis direction and the dimension of the holding means in the optical axis direction are added. By comparison, the dimension of the coupling means in the optical axis direction becomes smaller,
It is possible to obtain a compact optical device. In the optical device according to the fourth aspect, the connecting portion of the projecting means to the connecting means is provided at a position closer to the light receiving means in the optical axis direction than the connecting portion of the holding means to the connecting means. The direction in which the holding means thermally expands is opposite to the direction in which the coupling means thermally expands.

Therefore, by making the thermal expansion amount of the holding means and the thermal expansion amount of the coupling means the same, the distance between the projection means and the light receiving means is always constant irrespective of the temperature, and the projection means is changed by the temperature change. It is possible to reliably prevent the distance between the light receiving means and the light receiving means from changing. Further, since the coefficient of thermal expansion of the coupling means is made larger than the coefficient of thermal expansion of the holding means, the dimension of the coupling means in the optical axis direction is smaller than the dimension of the holding means in the optical axis direction. Obtainable.

In the optical apparatus according to the fifth aspect, since the light receiving means is the image pickup element, the subject image from the projection means can be surely converted into an electric video signal. In the optical apparatus according to claim 6, the projection means is a reduction optical system for reducing the subject image. Therefore, for example, the subject image formed on the primary imaging surface by the taking lens is further reduced by the reduction optical system. It can be projected on the light receiving means.

[Brief description of drawings]

FIG. 1 is a sectional view showing an electronic camera of a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing how the image pickup device is attached in the first embodiment.

FIG. 3 is a sectional view showing an electronic camera of a second embodiment of the present invention.

FIG. 4 is a sectional view showing an electronic camera according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing an electronic camera of a fourth embodiment of the present invention.

FIG. 6 is a sectional view showing an electronic camera of a fifth embodiment of the present invention.

[Explanation of symbols]

 11 Photographing lens 19 Image sensor 33 Housing 37,83 First coupling member 45,89 Second coupling member 81 Reduction optical system 93 Coupling member 97 Holding member

Claims (6)

[Claims] 1. An optical apparatus for projecting a subject image from a projection means held on one side of a housing onto a light receiving means held on the other side of the housing via a combining means, wherein: The connecting portion to the housing is provided at a position farther from the light receiving means in the optical axis direction with respect to the projection means, and the thermal expansion coefficient of the coupling means is set to be larger than the thermal expansion coefficient of the housing. Optical equipment characterized by being. 2. The optical device according to claim 1, wherein the housing is a first housing to which the image pickup means is connected,
An optical device which is separable into a second housing to which the coupling means is connected. 3. An optical apparatus for projecting a subject image from a projection means held on one side of a housing onto a light receiving means held on the other side of the housing via a holding means, wherein: While connecting the holding means to the other side through the coupling means, a connecting portion of the coupling means to the housing,
It is provided at a position farther from the projection means in the optical axis direction than the connecting portion of the holding means to the coupling means, and the thermal expansion coefficient of the coupling means is made larger than the thermal expansion coefficients of the housing and the holding means. Optical equipment characterized by 4. The projection means is connected to one side of the coupling means, and the light receiving means for receiving the subject image from the projection means is arranged on the other side of the coupling means via the holding means, and the projection means is provided. The connecting portion of the connecting means to the connecting means is provided at a position closer to the light receiving means in the optical axis direction than the connecting portion of the holding means to the connecting means, and the thermal expansion coefficient of the connecting means is held. An optical device having a coefficient of thermal expansion larger than that of the means. 5. The optical device according to claim 1, wherein the light receiving unit is an image pickup device. 6. The optical device according to claim 1, wherein the projection unit is a reduction optical system that reduces a subject image.