JP2001066508A - Optical equipment - Google Patents

Abstract

(57) [Problem] To use an optical element that reflects light incident from a surface inside the element and emits the light, a light amount adjusting device or the like is often arranged on the object side of the optical element, and the optical element It is difficult to remove dust and the like adhering to the surface on the incident side. SOLUTION: An optical element 6 for reflecting object light incident from an incident refraction surface R1 formed on an element surface on a reflection surface formed on the element inner surface and emitting the object light from an exit refraction surface R8 formed on the element surface. An optical apparatus is provided by providing a cover member 2 which is arranged on the object side of the incident refraction surface and is made of a transparent parallel plate or the like which is transparent in the visible wavelength region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system for reflecting object light incident from an incident refraction surface formed on a surface on a reflection surface formed on an inner surface and emitting the object light from an exit refraction surface formed on the surface. The present invention relates to an optical device including an element, such as an electronic still camera and a video camera.

[0002]

2. Description of the Related Art An image pickup by a still camera or a video camera is performed by converting a subject image formed on an image pickup device such as a CCD by an optical system into an electric signal by the image pickup device.

As an optical system of such a camera, a lens unit in which a plurality of lenses are aligned in an optical axis and incorporated in a lens barrel is often used. As an alternative, Japanese Patent Application Laid-Open No. Hei 8-237531 is used. And Japanese Patent Application Laid-Open No. 8-29
No. 2372 discloses an object refraction surface formed on an element surface, in which object light (subject light) incident from an incident refraction surface formed on the element surface is repeatedly reflected by a plurality of reflection surfaces formed on the element inner surface. There has been proposed an optical element that emits light from an imaging device and forms an image on an image sensor.

[0004]

Since such an optical element is integrally formed, an aperture (light amount adjusting device) is necessarily disposed on the object side or the image plane side of the optical element. When it is disposed on the surface side, the distance from the entrance surface to the entrance pupil increases, so that it is necessary to increase the size of the optical element in order to allow the light flux having the maximum angle of view to pass.

Further, since the telecentric condition required from the structure of an image pickup device such as a CCD is greatly deviated,
It is reasonable to dispose it closer to the object than the optical element.

Further, it is cost-effective to manufacture such an optical element by plastic injection molding.

Considering such conditions, from the object side,
First, there is an aperture, and immediately after that, a plastic optical element is arranged. In this case, there is a high probability that dust in the object side air will adhere to the surface of the optical element.

However, if there is a stop or the like on the object side of the optical element, there is a problem that it is difficult to remove dust and the like adhering to the surface of the optical element.

Further, when ultraviolet rays are directly incident on a plastic optical element, the possibility of yellowing due to deterioration of the material is high.

Further, since an image pickup device such as a CCD has a high sensitivity in the infrared region, it is usually necessary to arrange an infrared cut filter between the optical system and the image pickup device.

Further, since this optical element has a plurality of reflecting surfaces, it is necessary to take measures to prevent the occurrence of so-called ghost.

[0012]

In order to solve the above-mentioned problems, an optical apparatus according to a first aspect of the present invention uses an object refracting surface formed on a surface of an element to project object light incident on the inner surface of the element. It has an optical element that reflects light from a reflecting surface and emits light from an exit refracting surface formed on the element surface, and a cover member that is disposed closer to the object side than the incident refracting surface and is made of a parallel plate or the like that is transparent in the visible wavelength region. It is composed.

By providing the cover member as described above, adhesion of dirt, dust, and the like existing in the outside of the device to the surface of the optical element (particularly, the incident refraction surface) is prevented.

When a light amount adjusting device for adjusting the amount of light incident on the incident refracting surface is disposed closer to the object side than the incident refracting surface, the cover member is arranged closer to the object side than the light amount adjusting device. Is also good.

The cover member as described above may have a function of cutting light in the ultraviolet wavelength range, so that deterioration of the material and yellowing of the plastic optical element due to ultraviolet rays may be prevented.

Further, the cover member as described above may have a function of cutting light in an infrared wavelength region, so that an infrared cut filter conventionally required for an image pickup device such as a CCD may be omitted.

Further, a light blocking means for blocking object light which does not contribute to image formation by the optical element may be provided on the object side of the cover member to prevent ghost from occurring.

Further, in the optical apparatus according to the second aspect of the present invention, the object light incident from the incident refraction surface formed on the element surface is reflected by the reflection surface formed on the element inner surface, and the emission light formed on the element surface is emitted. An optical element that emits light from the refraction surface and an ultraviolet cut unit that is disposed closer to the object than the incident refraction surface and has a light transmittance in the ultraviolet wavelength region lower than the light transmittance in the visible wavelength region. Here, the ultraviolet ray cut means may be a member separate from the optical element, or may be formed by coating the surface of the optical element.

This makes it possible to prevent deterioration of the material and yellowing of the plastic optical element due to ultraviolet rays.

[0020]

FIG. 1 conceptually shows the structure of a camera (optical apparatus) according to an embodiment of the present invention. 1
Denotes a camera body, and 2 denotes a cover member (a cover member and an ultraviolet ray cut member referred to in the claims) fitted in a photographing opening of the camera body.

In the present embodiment, the cover member 2 is formed of a parallel plate, is transparent in the visible wavelength region, and has both a transmittance of light in the ultraviolet wavelength region and a transmittance of light in the infrared wavelength region. It is lower than the light transmittance of the region.

The cover member 2 is made of, for example, a material having a low transmittance of light in the ultraviolet wavelength region (BAL manufactured by OHARA Corporation).
2. A parallel plate is formed from flint glass such as BAH10, LAM52, and FTM16), and this parallel plate is coated with a material having low transmittance of light in the infrared wavelength region.

Reference numeral 3 denotes a light-shielding mask integrally formed on the surface of the cover member 2 on the subject side (object side) by painting, printing, vapor deposition, or the like.

Reference numeral 4 denotes a diaphragm blade provided in a diaphragm device (light amount adjusting device). The diaphragm blade 4 has a plurality of light passage openings having different diameters. The aperture blade 4 is driven by a not-shown actuator in a plane perpendicular to the incident optical axis, and adjusts the amount of light incident on an optical element 6 described later by the size of the diameter of a light passing port located on the incident optical axis. I do.

Reference numeral 5 denotes an opening diameter defining member having an opening having a diameter larger than the maximum diameter light passage opening formed on the diaphragm blade 4.

Reference numeral 6 denotes an optical element, the specific structure of which will be described with reference to FIGS. The optical element 6 is integrally formed of plastic using an injection molding method, and includes an incident refracting surface R1 serving as a light incident surface, an exit refracting surface R8 serving as a light emitting surface, and a plurality of inner surfaces in a longitudinal direction. A first reflecting surface group in which the reflecting surfaces R2, R4, and R6 are arranged; and a plurality of inner reflecting surfaces R that are arranged substantially opposite to the first reflecting surface group.
And a second reflecting surface group having R3, R5, and R7.

The inner reflecting surface R2 is a plane mirror, and the optical element 6 has a shape in which a portion K where the incident refracting surface R1 and the inner reflecting surface R2 are formed protrudes.

The internal reflecting surfaces R3 to R7 are off-axial reflecting surfaces having a curvature, and the internal reflecting surfaces R3, R
5 and R7 are concave mirrors, and the inner reflecting surfaces R4 and R6 are convex mirrors.

Reference numerals A and A 'denote projections which are integrally formed on both ends in the longitudinal direction of the optical element 6 and do not perform an optical function. These projections A and A 'have side planes that are continuous without any step on the element side surface, and have a top plane and a bottom plane that are perpendicular to these side planes. Further, the longitudinal end face of the protrusion A is
It has an end plane perpendicular to the side plane, the top plane and the bottom plane.

The optical element 6 thus formed is joined or held to the camera body 1 with the projections A and A 'as positioning references.

Reference numeral 9 shown in FIG. 1 denotes an image pickup device such as a CCD for picking up an image formed by subject light emitted from the optical element 6.

The specific arrangement of the optical element 6, the cover member 2, the aperture blade 4, and the image pickup element 9 in the camera is shown in FIG.
And it becomes as shown in FIG.

In the camera configured as described above, the subject light passing through the opening of the light-shielding mask 3 passes through the cover member 2, the light passage opening of the diaphragm blade 4 and the opening of the opening diameter defining member 5, and becomes an optical element. No. 6 is incident on the incident refraction surface R1.

In the optical element 6, the light incident from the refracting surface R1 (the center of the light beam is shown by a dashed line in FIG. 3) is redirected by a plane mirror R2 to form a concave mirror R3 and a convex mirror R3.
4, the reflection is repeated by the concave mirror R5, the convex mirror R6, and the concave mirror R7, and the light is emitted from the exit refracting surface R8. The light emitted from the exit refraction surface R8 forms an image on the image sensor 9.

Here, the cover member 2 attached to the photographing opening of the camera body 1 is provided inside the camera in which the above-mentioned members and elements are accommodated, such as dust, dust, water, etc., existing outside the camera through the photographing opening. To prevent intrusion. Thereby, especially, the incident refraction surface R of the optical element 6 which affects the imaging.
It is possible to prevent dust and the like from adhering to 1.

Therefore, as in the present embodiment, the aperture blade 4 and the open-diameter defining member 5 are arranged closer to the subject than the optical element 6, and if dust or the like adheres to the incident refracting surface R1 of the optical element 6, In a camera in which the removal is difficult, such a work for removing dust and the like can be omitted.

In this embodiment, since the cover 2 is a parallel flat plate having two flat surfaces, it is possible to prevent the deterioration of the imaging performance of the optical element 6 due to the addition of the cover 2. .

Further, due to the above-described configuration, the cover member 2 allows the visible wavelength region light of the subject light to pass with a high transmittance, but transmits the ultraviolet wavelength region light only with a low transmittance. For this reason, it is possible to prevent deterioration of the material and yellowing of the plastic optical element 6 due to the incidence of ultraviolet rays. Since the deterioration of the material depends on the cumulative irradiation amount of ultraviolet rays, the life of the optical element 6 can be doubled if the transmittance of the ultraviolet light in the ultraviolet region of the cover member 2 is 50%.

In a state where the portion of the aperture blade 4 other than the light passage opening and the opening of the opening diameter defining member 5 overlap,
Since the subject light does not enter the optical element 6, it is possible to reliably prevent the above-described influence of the ultraviolet light.

Further, since the cover member 2 transmits only the infrared wavelength region light of the subject light with a low transmittance, the infrared cut filter which is conventionally required for a camera using an image pickup device such as a CCD is unnecessary. can do. However, there is also the aspect that further improvement in performance can be expected if used in combination with an infrared cut filter.

Further, the light shielding mask 3 and the opening diameter defining member 5 can greatly restrict the light flux which does not contribute to the image formation by the optical element 6 out of the light flux passing through the light passage opening of the diaphragm blade 4, so that the ghost image can be obtained. Can be effectively prevented.

In this embodiment, the case where the cover member 2 is arranged on the subject side with respect to the aperture blade 4 has been described. However, the cover member may be arranged anywhere on the subject side with respect to the optical element.

In this embodiment, the case where the light-shielding mask 3 is integrally formed on the cover member 3 by painting, printing, or the like has been described. However, the light-shielding mask 3 is a member separate from the cover member 2 instead of the light-shielding mask 3. A member may be used.

Further, in the present embodiment, the case where the cover member 2 which is a member separate from the optical element 6 has an ultraviolet cut effect has been described. May be coated.

Further, the present invention can be applied to the case where an optical element having a shape other than the shape described in this embodiment is used. That is, any optical element may be used as long as the object light incident from the incident refraction surface formed on the element surface is reflected by the reflection surface formed on the element inner surface, and emitted from the exit refraction surface formed on the element surface.

In this embodiment, a camera has been described. However, the present invention can also be applied to optical devices other than the camera using the above-described optical element, for example, a finder and an optical measurement pickup.

[0047]

As described above, according to the first aspect of the present invention, the cover member is disposed closer to the object side than the optical element. It is possible to reliably prevent the adhesion of existing dust and the like. In particular, when an optical element that reflects light incident from the surface and emits the light within the element is used, the light amount adjusting device or the like is often arranged on the object side of the optical element, and the light amount adjusting device is attached to the incident side surface of the optical element. The effect is great because it is difficult to remove dust and the like.

If the cover member has a function of cutting light in the ultraviolet wavelength region, deterioration of the material and yellowing of the plastic optical element due to ultraviolet rays can be prevented.

If the cover member has a function of cutting light in the infrared wavelength region, an infrared cut filter conventionally required for an image pickup device such as a CCD can be eliminated.

Further, if a light shielding means for blocking object light which does not contribute to the image formation by the optical element is provided on the object side of the cover member, it is possible to prevent the occurrence of ghost.

According to the second aspect of the present invention, since the ultraviolet ray cut means is disposed closer to the object side than the optical element which reflects the light incident from the surface and emits the light within the element, it is integrally formed of plastic. It is possible to prevent the deterioration and yellowing of the material of the optical element, which is often caused by ultraviolet rays.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a camera according to an embodiment of the present invention.

FIG. 2 is a perspective view of an optical element used in the camera.

FIG. 3 is an explanatory diagram showing an optical function of the optical element.

FIG. 4 is an arrangement diagram of members and elements in the camera.

FIG. 5 is an arrangement diagram of members and elements in the camera.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Camera main body 2 Cover member 3 Light-shielding mask 4 Aperture blade 5 Opening diameter defining member 6 Optical element R1, R8 Refraction surface R2 Internal reflection surface (plane mirror) R3 to R7 Internal reflection surface (off-axial reflection surface)

Continued on the front page (72) Inventor Hiroaki Hoshi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Kenshi Akiyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Toshihiro Sunaga 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H018 AA00 2H087 KA03 KA14 RA34 RA43 TA01 TA02 UA01

Claims (15)

[Claims] An optical element that reflects object light incident from an incident refraction surface formed on an element surface on a reflection surface formed on an element inner surface, and emits the object light from an exit refraction surface formed on the element surface. An optical device, comprising: a cover member that is disposed closer to an object side than an incident refraction surface and is transparent in a visible wavelength region. 2. A light amount adjusting device for adjusting an amount of light incident on the incident refracting surface is disposed closer to the object side than the incident refracting surface, and the cover member is disposed closer to the object side than the light amount adjusting device. The optical device according to claim 1, wherein: 3. The optical device according to claim 1, wherein the cover member is attached so as to cover a light entrance opening formed in the device main body. 4. The optical device according to claim 1, wherein the cover member is a parallel flat plate. 5. The optical apparatus according to claim 1, wherein the transmittance of the cover member for light in an ultraviolet wavelength region is lower than the transmittance of light for a visible wavelength region. 6. The optical device according to claim 1, wherein the optical element is formed of plastic. 7. The optical apparatus according to claim 1, wherein the transmittance of the cover member for light in an infrared wavelength region is lower than the transmittance of light for a visible wavelength region. 8. The optical apparatus according to claim 1, further comprising an image pickup device for picking up an image formed by the object light emitted from the exit refraction surface. 9. The light-shielding device according to claim 1, wherein a light-shielding unit that blocks object light that does not contribute to image formation by the optical element is provided on the object side of the cover member. Optical equipment. 10. The optical apparatus according to claim 9, wherein the light shielding unit is a member separate from the cover member. 11. The optical apparatus according to claim 9, wherein the light shielding unit is formed integrally with an object-side surface of the cover member. 12. An optical element that reflects object light incident from an incident refraction surface formed on an element surface on a reflection surface formed on an element inner surface and emits the object light from an exit refraction surface formed on the element surface. An optical apparatus comprising: an ultraviolet ray cut unit disposed closer to an object side than an incident refraction surface and having a light transmittance in an ultraviolet wavelength region lower than a light transmittance in a visible wavelength region. 13. The optical device according to claim 12, wherein the ultraviolet light cut unit is a member separate from the optical element. 14. The optical apparatus according to claim 12, wherein said ultraviolet ray cut means is formed by coating a surface of said optical element. 15. The optical apparatus according to claim 12, wherein the optical element is formed of plastic.