JP2003185905A - Camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera constituted so that a change in the focal position of a photographic lens due to a temperature change can be manually corrected. <P>SOLUTION: The camera is provided with temperature scale member with a prescribed temperature scale; a temperature correcting operation member which is equipped with an indicating part for indicating the temperature scale of the temperature scale member and which is rotated with an external operation; and a lens barrel which is moved in the optical axis direction in accordance with the rotation of the temperature correcting operation member while holding the photographic lens. When the indicating part is aligned with the temperature scale of the temperature scale member equivalent to the environmental temperature of the camera, the lens barrel is moved in the optical axis direction by a value nearly equivalent to the variation of the focal position of the photographic lens changing in accordance with the temperature change. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera in which back focus, which expands and contracts due to temperature change of a taking lens, is corrected by simple means.

[0002]

2. Description of the Related Art In recent years, a photographing lens used for a low-priced camera has been a combination of a glass lens and a plastic lens, or a plastic lens. In addition, many low-priced cameras do not have a focus adjustment mechanism such as an autofocus mechanism, and often use a fixed focus method in which the focus position is set to the hyperfocal length.

Compared to glass lenses, plastic lenses are more susceptible to changes in temperature and are more prone to problems such as focal point changes due to expansion and contraction. However, conventional low-priced cameras do not have an autofocus mechanism, so it is not possible to electrically convert and process temperature changes to correct the focus position, and cameras that have taken special measures cannot There wasn't.

On the other hand, in the optical device (collimator),
A lens barrel that holds the lens and whose barrel length changes according to temperature changes is provided, and the lens focus position is fixed by canceling the changes in the lens focal position and the lens barrel length caused by temperature changes. Japanese Unexamined Patent Publication (Kokai) No. 6-130267 discloses a technique formed of a material that can be retained in the above.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have proposed, in order to correct the change in the focal position (hereinafter, referred to as back focus fb) due to the above-mentioned plastic lens, Japanese Patent Laid-Open Publication No. Hei 6 (1999) -6.
Recalling that the technology of Japanese Patent Laid-Open No. 130267 has been developed to select a lens barrel whose length changes by canceling the change in the focal position of the photographing lens so as to keep the focal position of the photographing lens of the camera at a fixed position. did.

On the other hand, the amount of change in the back focus fb due to the plastic lens is quite large, and according to the experiments by the inventors, when the temperature change with respect to the reference temperature is 20 ° C., the amount of change in the back focus fb is about 0. 05 mm
Met. When the lens barrel holding this plastic lens is formed of, for example, ABS resin having a large linear expansion coefficient, the linear expansion coefficient is 10.0 × 10 ⁻⁵ , so that the length of the lens barrel is 20 ° C. when the temperature change is 20 ° C. 25 mm is required. Therefore, if a material with a coefficient of linear expansion of 5.0 × 10 ⁻⁵ is used,
The length of the lens barrel is required to be 50 mm.

However, even if the length of the lens barrel is 25 mm,
It is difficult to realize a thin camera that is thin on the market at present, and this leads to an increase in the size of the camera.

Therefore, it is necessary to select a material having a larger linear expansion coefficient and satisfying various characteristics such as strength and moldability which can be used for the lens barrel, and the material selection is extremely limited. Even if it could be realized, the cost would be high.

The present invention has been made in view of the above problems, and it is an object of the present invention to propose a camera capable of manually correcting a change in the focal position of a photographing lens due to a temperature change.

[0010]

The above object can be achieved by the following means.

[0011] A temperature scale member provided with a predetermined temperature scale, an instruction unit for instructing the temperature scale of the temperature scale member, a temperature correction operation member which is rotated by an external operation, a photographing lens are held, and the temperature A lens barrel that moves in the optical axis direction by rotation of the correction operation member, rotates the temperature correction operation member, and matches the temperature scale of the temperature scale member corresponding to the temperature under the environment of the camera with the indicator unit. A camera characterized in that, when the lens barrel is moved, the lens barrel moves in an optical axis direction by a value substantially corresponding to a change amount of a focal position of the photographing lens which changes due to a temperature change.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Three types of embodiments of a camera of the present invention will be described in detail with reference to the drawings.

[First Embodiment] A first embodiment will be described with reference to FIGS. 1 to 3.

FIG. 1 is a view of a mechanism for manually correcting a change in the focal position of a photographing lens due to a temperature change, FIG. 2 is a view of a temperature scale member, and FIG. 3 is a view of a thermometer for digital display.

In FIG. 1, the taking lens 1 is composed of a first lens 11 and a second lens 12, and the subject light is imaged on the image forming plane of the image pickup device 2. First lens 11 and second
The lens 12 is made of plastic and has a lens barrel 2
It is held at 1.

The taking lens 1 is of a fixed focus type in which the focus position is set to the hyperfocal length.

The lens barrel 21 is fitted to the guide shaft 22 and is movable in the optical axis direction. The guide shaft 22
Although only one is shown in the figure, two guide shafts 22 are arranged.

Reference numeral 23 denotes a temperature correction operation member, which is an operation portion 23a which is rotated by pinching it with a fingertip, and a temperature scale member 24.
Indicator 23b for instructing the temperature scale 24a, a male screw portion 23c screwed to the lens barrel 21, and a holder 2 rotatably held by an immovable fixing member 25 such as a camera body.
4d. Since the E-ring 26 is attached to the end of the holding portion 24d, the temperature correction operation member 23 can only rotate without moving in the axial direction.

Here, the back focus fb of the photographic lens 1 extends substantially linearly with respect to a temperature change as the temperature rises. That is, the subject light forms an image behind the image formation plane of the image sensor 2. In order to solve this problem, it is sufficient to move the taking lens 1 to the subject side by the amount that the back focus fb is extended.

Therefore, when the camera is assembled so that the taking lens 1 is focused on the image pickup element 2 at the standard temperature and the temperature of the camera under the environment changes, the temperature between the environment temperature and the standard temperature. Back focus fb caused by the difference
The lens barrel 21 is moved back and forth in the optical axis direction by the amount of change.

For example, it is assumed that the standard temperature is 20 ° C. and the temperature under the environment of the camera is 35 ° C. as shown in FIG. At this time, the back focus fb is 0.
It is assumed that the extension is 038 mm. In such a case, the lens barrel 21 may be moved 0.038 mm forward, that is, toward the subject.

To this end, the operating portion 23a of the temperature correction operating member 23 is pinched with a fingertip and rotated to the right, and the indicating portion 23b is moved to the temperature scale 24 of the temperature scale member 24 as shown in FIG.
Match the position corresponding to 35 in the middle of 30 and 40 of a. At this time, the male screw portion 23c is a right-hand screw, and the screw lead is formed in correspondence with the angle of the temperature scale 24a of the temperature scale member 24 and the temperature change amount of the back focus fb of the photographic lens 1, so that the lens The lens barrel 21 moves 0.038 mm forward.

On the other hand, when the ambient temperature of the camera is equal to or lower than the standard temperature, the operating portion 23a may be rotated leftward.

In this way, the temperature change of the back focus fb of the taking lens 1 can be corrected manually.

Even if the result of correction is slightly different from the back focus change amount due to an error or the like when the indicator 23b is matched with the temperature scale 24a, the screw of the screw is set so as to be within the depth of focus of the taking lens 1. There is no problem because the lead is set.

[Second Embodiment] A second embodiment will be described with reference to FIGS.

FIG. 4 is a view of a mechanism for manually correcting the change in the focal position of the taking lens due to temperature change, and FIG. 5 is a view of the temperature scale member.

In FIG. 4, the taking lens 1 is composed of a first lens 11 and a second lens 12, and the subject light is focused on the image pickup device 2. First lens 11 and second lens 1
2 is made of plastic and is held by the lens barrel 31.

Further, the taking lens 1 has a standard temperature (for example, 2
It is a fixed focus method with the focus position set to the hyperfocal length at 0 ° C.

The lens barrel 31 has a male screw portion 31a and is screwed with a female screw 32a provided on an immovable fixing member 32 such as a camera body. In addition, the lens barrel 31 has an operation unit 31b for pressing and rotating the fingertip, and an instruction unit 31c for instructing the temperature scale 33a of the temperature scale member 33. The operating portion 31b is engraved with a let for easy operation.

If the temperature of the camera under the environment of the camera is 35 ° C. as shown in FIG. 3 as in the first embodiment, the operating portion 31b is pressed with the fingertip and the lens barrel. By rotating 31 in the clockwise direction, as shown in FIG. 5, the indicating portion 31c is aligned with a position corresponding to an intermediate position 35 between 30 and 40 of the temperature scale 33a of the temperature scale member 33. At this time,
Since the male screw portion 31a is a left screw and is formed on the lead of the screw corresponding to the angle change of the temperature scale 33a of the temperature scale member 33 and the temperature change amount of the back focus fb of the photographing lens 1, the lens barrel 31 is The temperature shift amount of the back focus fb of the taking lens 1 is moved forward, that is, toward the subject side.

On the other hand, when the ambient temperature of the camera is equal to or lower than the standard temperature, the operation portion 31b may be rotated counterclockwise.

Thus, the temperature change of the back focus fb of the taking lens 1 can be manually corrected.

Even if the result of the correction is slightly different from the back focus change amount due to an error or the like when the instruction section 31c is matched with the temperature scale 33a, the screw of the screw is set so as to be within the depth of focus of the taking lens 1. There is no problem because the lead is set.

The thermometer of FIG. 3 according to the first embodiment and the second embodiment is for checking the temperature, so any thermometer may be used. Also, a small thermometer may be incorporated in the camera.

[Third Embodiment] A third embodiment will be described with reference to FIG.

FIG. 6 is a diagram of a mechanism for manually correcting a change in the focal position of the taking lens due to a temperature change.

In FIG. 6, the taking lens 1 is composed of a first lens 11 and a second lens 12, and the subject light forms an image on the image pickup device 2. First lens 11 and second lens 1
2 is made of plastic and is held by the lens barrel 41.

Further, the taking lens 1 has a standard temperature (for example, 2
It is a fixed focus method with the focus position set to the hyperfocal length at 0 ° C.

The lens barrel 41 is fitted on the guide shaft 42 and is movable in the optical axis direction. The guide shaft 42
Although only one is shown, three guide shafts 42 are arranged at equal angles.

A drive gear 43 is formed coaxially with an operation knob (not shown), and is connected to a rack 41a formed on the lens barrel 41 via a plurality of reduction gear trains 44. The drive gear 43 is also meshed with the rack 45 a of the movable indicator plate 45, and the indicator portion 45 of the movable indicator plate 45.
b indicates the thermometer 46. The thermometer 46 is an analog thermometer in which the portion where the temperature has risen is painted black.

If the thermometer 46 indicates 35 ° C. as in the first and second embodiments, the operating knob (not shown) is rotated counterclockwise to The drive gear 43 is rotated in the same direction to move the movable indicator plate 45.
The instructing unit 45b of 5 indicates the thermometer 46 at 35 ° C. As a result, the final stage gear of the reduction gear train 44 rotates clockwise, so that the lens barrel 41 moves forward, that is, toward the subject, via the rack 41a.

At this time, the temperature scale 46a of the thermometer 46
Since the deceleration gear train 44 is configured to have a reduction ratio corresponding to the pitch and the amount of temperature change of the back focus fb of the taking lens 1, the lens barrel 41 moves forward only by the amount of temperature change of the back focus fb of the taking lens 1. Moving.

On the other hand, when the ambient temperature of the camera is below the standard temperature, the operation knob may be rotated clockwise.

In this way, the temperature change of the back focus fb of the taking lens 1 can be manually corrected.

Further, even if the result of the correction is slightly different from the change amount of the back focus due to an error or the like when the instruction unit 45b is matched with the temperature scale 46a, the reduction ratio is set so as to be within the depth of focus of the taking lens 1. Since it is set, there is no problem.

Further, as the thermometer, a reversible temperature indicating ink (for example, liquid crystal ink) may be used to constitute the temperature scale.

Although the camera described above is a digital camera in which the subject light is imaged on the image sensor 2 by the taking lens 1, it is not limited to a digital camera, and a film is loaded and imaged on the film. It may be a conventional camera.

[0049]

According to the camera of the present invention, since the change in the focal position of the photographing lens due to the temperature change can be corrected by the manual operation, the good focus can be guaranteed even if the temperature changes.

[Brief description of drawings]

FIG. 1 is a diagram of a mechanism for manually correcting a change in a focal position of a photographing lens due to a temperature change.

FIG. 2 is a diagram of a temperature scale member.

FIG. 3 is a diagram of a thermometer for digital display.

FIG. 4 is a diagram of a mechanism for manually correcting a change in the focal position of the taking lens due to a change in temperature.

FIG. 5 is a diagram of a temperature scale member.

FIG. 6 is a diagram of a mechanism for manually correcting a change in the focal position of the taking lens due to a temperature change.

[Explanation of symbols]

1 Shooting lens 2 image sensor 21, 31, 41 lens barrel 23 Temperature correction operation member 23b, 31c, 45b Indicator 24,33 Temperature scale member 32 fixing member 43 Drive gear 45 Movable indicator 46 Thermometer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 17/02 H04N 5/232 E 17/18 G03B 3/00 Z H04N 5/232 G02B 7/04 DF Term (reference) 2H044 AC00 AE06 AF01 AH01 BD02 BD11 2H100 BB05 BB06 EE00 2H102 AA71 CA00 CA01 5C022 AA13 AB44 AC42 AC54 AC74

Claims (4)

[Claims] 1. A temperature scale member provided with a predetermined temperature scale, an instruction unit for instructing the temperature scale of the temperature scale member, a temperature correction operation member that is rotated by an external operation, and a photographing lens, A lens barrel that moves in the optical axis direction by the rotation of the temperature correction operation member, and rotates the temperature correction operation member, and causes the indicator to correspond to the temperature of the environment of the camera. The camera is characterized in that the lens barrel moves in the optical axis direction at a value substantially corresponding to the amount of change in the focal position of the taking lens that changes due to temperature changes when the above condition is met. 2. The camera according to claim 1, wherein the temperature correction operation member and the lens barrel are integrally formed. 3. The camera according to claim 1, further comprising a thermometer. 4. The camera according to claim 1, wherein the temperature scale member is a thermometer.