JP2010060582A - Compound optical system and optical device - Google Patents

Abstract

A composite optical system capable of acquiring information related to sunlight and an optical apparatus having the composite optical system are provided.
A composite optical system 1 included in an optical apparatus such as a photographing system 40 is arranged in front of an imaging optical system 2 and the imaging optical system 2 and below an optical axis of the imaging optical system 2. The first reflecting member 3 that reflects light from the sun by the reflecting surface facing upward and guides it to the entrance pupil of the imaging optical system 2, and between the imaging optical system 2 and the first reflecting member 3 And a dimming means 5 for dimming light reflected by the first reflecting member 3.
[Selection] Figure 2

Description

  The present invention relates to a composite optical system and an optical apparatus.

A camera using an electronic image sensor that is also used outdoors for surveillance purposes or on-board has been developed (see, for example, Patent Document 1). Such a camera is affected in various ways by the incident direction of sunlight and by weather conditions. Therefore, it is useful to provide a mechanism for monitoring the intensity and direction of sunlight in the imaging optical system of such a camera, and to take measures against sunlight according to the signal. Can be applied to various applications such as indoor / outdoor lighting on / off, brightness adjustment, light collection switching, camera direction change, air conditioning switching, blind switching, etc. It becomes.
JP-A-11-0778737

  However, the intensity of sunlight is intense, and if sunlight is captured directly by the imaging optical system, there are problems such as saturation of the light intensity and damage to the device. Furthermore, it has been difficult to form a sun image in combination with a monitoring image.

  The present invention has been made in view of such a problem, and can acquire information related to sunlight by a rational optical arrangement, and can also generate harmful ghost images that are often generated in the screen by sunlight. It is an object of the present invention to provide a composite optical system that can be reduced, and an optical device having the composite optical system.

  In order to solve the above-described problem, the composite optical system according to the first aspect of the present invention is disposed in front of the imaging optical system and the imaging optical system and below the optical axis of the imaging optical system. A first reflecting member that reflects light from the sun by the reflecting surface and guides it to the entrance pupil of the imaging optical system, and is disposed on an optical path that connects the imaging optical system, the first reflecting member, and the sun. And a dimming means for dimming light reflected by the reflecting member.

  In such a composite optical system, the first reflecting member is preferably a convex mirror.

  In addition, such a composite optical system preferably has a blocking unit that blocks light directly incident on the imaging optical system from light from the sun.

  In such a composite optical system, it is preferable that the reflection surface of the first reflecting member has a reflectance of 5% or less of normal incident light.

  Further, such a composite optical system is disposed above the optical axis of the imaging optical system and on the optical path between the first reflecting member and the imaging optical system, and reflected by the first reflecting member. It is preferable to further include a second reflecting member that reflects light by a reflecting surface directed downward and guides the light to the entrance pupil of the imaging optical system.

  At this time, it is preferable that the second reflecting member is disposed so as to block the light directly incident on the imaging optical system out of the light from the sun over at least a considerable time during sunlight.

  In such a composite optical system, at least one of the reflecting members arranged in front of the imaging optical system is a substantially rotating hyperboloid having a convex reflecting surface, and the first hyperboloid of the hyperboloid The focal point is below the optical axis of the imaging optical system, and at least when observing light, the second focal point or the image of the second focal point is arranged so as to substantially coincide with the entrance pupil of the imaging optical system. It is preferable.

  Further, in such a composite optical system, all the reflecting members arranged in front of the imaging optical system are surface mirrors made of a member that absorbs a considerable amount of light. It is preferable to form a reflection reducing means for reducing the reflectance of light having a wavelength that is perpendicularly incident on the reflecting surface to 3% or less.

  Further, in such a composite optical system, it is preferable that the imaging optical system is attached to the vehicle, and the first reflecting member is a part of the vehicle body of the vehicle.

  The composite optical system according to the second aspect of the present invention includes an imaging optical system and sunlight that is emitted from the sun and reflected by the first reflecting member in front of the imaging optical system and passes through the entrance pupil. And a dimming unit disposed on the road for dimming light.

  An optical device according to the present invention includes any one of the above-described composite optical systems, an image sensor that detects an image formed by the composite optical system, and light from the sun among the images detected by the image sensor. And a detection unit that detects at least one of the position of the sun and the intensity of light from the image.

  When the composite optical system according to the present invention and the optical apparatus having the composite optical system are configured as described above, the solar detection optical system can be integrated into the screen of the imaging optical system using the imaging optical system. In addition, while including the action of reducing the ghost of sunlight, information can be acquired by an optical system that is extremely compact, easy to adjust, has few members, and is inexpensive.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, an imaging apparatus mounted on a vehicle and monitoring the front of the vehicle will be described as an example using FIG. 1 as an optical device having the composite optical system according to the present invention. FIG. 1 is a diagram showing a cross section of a vehicle (passenger car) A, and an imaging camera K for front monitoring is installed at the top of a windshield inside the vehicle. The imaging camera K faces forward in a substantially horizontal direction or slightly downward, and the bonnet B of the vehicle A is reflected near the lower side of the field of view.

  The vehicle A can provide sunlight reflected by the bonnet B on the focal plane of the imaging camera K in the daytime and in direct sunlight. The shape of the bonnet B is normally a convex surface, the sun reaches a focal plane as a small approximate point image, and a wide range of solar altitudes and orientations can be captured as an image. Since the azimuth | direction of the sun with respect to the imaging camera K and the coordinate on the imaging surface (not shown) of the imaging camera K respond | correspond one-to-one, the azimuth | direction information of solar, present time, a place ( Latitude, longitude, height) and at least one piece of information in the direction and orientation of the vehicle A can be obtained in real time. At the same time, the sunshine situation can be estimated in real time from the absolute amount and change amount of the brightness (illuminance) of the sun image on the imaging surface.

[First Embodiment]
FIG. 2 shows the above-described imaging camera K, in which a wide-angle lens (imaging optical system) intended for white line detection is formed with a substantially point image of sunlight, and the current weather condition from its position coordinates and intensity, and FIG. 2 is a cross-sectional view of the optical system of the composite optical system 1 according to the first embodiment in which the relative position coordinates of the sun with respect to the imaging camera K are to be detected. The composite optical system 1 includes an imaging optical system 2, a first reflecting member 3 disposed in front of the imaging optical system 2 and below the optical axis and having a reflecting surface facing upward. It is composed of The first reflecting member 3 is a convex mirror arranged so that the optical axis passes through the position of the substantially entrance pupil of the imaging optical system 2, and reflects the direct light from the sun to capture the imaging optical system 2. Is an optical system that forms a sun image on the lower surface of the field of view of the imaging surface I, that is, the foot portion. The composite optical system 1 also has a blocking section 4 that blocks direct sunlight (not shown) incident from the upper part of the imaging optical system 2. For example, as shown in FIG. The lens 2a on the most object side of the optical system 2 is attached to the upper part of the lens surface on the most object side.

  When the composite optical system 1 is applied to a camera mounted on a vehicle, as described above, the first reflecting member 3 may be attached as a dedicated member on the hood B of the vehicle A shown in FIG. Alternatively, a part of the bonnet B may be used as the first reflecting member 3. The bonnet B is usually covered with a paint having a low reflectance in order to reduce as much as possible the dazzling during driving. Further, when the first reflecting member (convex mirror) 3 is provided as a separate member from the bonnet B, the first reflecting member (convex mirror) 3 is made of the same material as the high-density density filter having a density of about 4 that suppresses the transmission of sunlight. An image sensor that detects an image formed by the imaging optical system 2 (not shown, although not shown), does not return through the first reflecting member 3 regardless of whether the light beam is reflected or transmitted by the back surface. The device sensitivity can be reduced below.

However, sunlight is intense, and if the reflected light of sunlight L1 shown in FIG. 1 is directly guided to the imaging optical system 2, the illuminance on the imaging surface is too high. Therefore, the reflection surface of the first reflection member 3 guides the surface reflection light to the imaging optical system 2, and applies reflection reduction means (for example, an antireflection coating) to reduce the surface reflection light. It is desirable to suppress the reflectance at a predetermined wavelength to about 1 × 10 ⁻⁴ (0.01%).

Even if the reflection reducing means is applied to the reflecting surface of the first reflecting member 3 as described above, if the reflectance of sunlight is high, the amount of light incident on the imaging optical system 2 may be too much. In this case, dimming means 5 is provided on the optical path (lower part of the lens) on the object side surface of the lens (first lens) 2a disposed closest to the object side of the imaging optical system 2 (for example, an absorbing material). or by reflective material depositing with dimming effect of covering substance) be set to be approximately 1 × 10 ^-4 (0.01%) extent the total transmittance of the detection area of the image of the sun in the imaging device It is desirable.

  More specifically, as the imaging optical system 2, in the first embodiment, the embodiment described in Japanese Patent Publication No. 51-14017 is proportionally reduced to a predetermined focal length, and the focal length f1 = 2.55 mm, A lens having F / 4, an incident angle of 2ω = 180 degrees, and a maximum image height ymax = 3.86 mm was used. The first reflecting member (convex mirror) 3 that guides sunlight tilts a convex hyperboloid with a focal length f2 = −48.95 mm and K = 7.111 with respect to the optical axis of the imaging optical system 2 by 85 degrees. The position of the second focal point of the hyperboloid is 58.74 mm from the apex of the first reflecting member 3, and this is approximately matched with the position of the entrance pupil on the optical axis of the imaging optical system 2. The optical paths are described for typical light rays L2 to L5 having different altitudes in the south and middle of the sun. Further, at the upper end of the surface closest to the object side of the first lens 2a, in order to prevent an image of direct sunlight from being formed in the lower part (sky part) of the imaging screen, a blocking part (shielding object) in which light rays are not transmitted. 4 are arranged in close contact with each other.

  Here, when the first reflecting member 3 is configured as a separate member without using a part of the hood B of the vehicle A, the reflecting surface of the first reflecting member 3 can be optimized. In the case of autumn, even when the sunrise is true east, the sunset is true west, and the field angle is 180 degrees to the left and right, in principle, imaging is performed by paying attention to the mirror size of the first reflecting member 3. Light can be received on the surface I. By using the imaging optical system 2 having an incident angle greater than 180 degrees, it is not impossible to receive light from sunrise to sunset at the summer solstice, and it is possible to optimize the shooting range according to the purpose.

FIG. 3 shows a screen 20 schematically representing an image on the imaging surface I as a video, and in this case, a vertically long screen. In Japan, when the imaging optical system 2 is fixed in the south direction, the position of the sun 24 at a certain point in front of the south-south is shown assuming that the sun travels on the orbit 25. The sun image detection area is the lower area 23 of the screen 20. Further, as described above, the surface of the first lens 2a of the imaging optical system 2 is provided with the dimming means 5 for suppressing the transmittance only in the vicinity of the sunlight transmitting portion, and the sun image detection area. Since the total transmittance of 23 is reduced to about 1 × 10 ⁻⁴ (0.01%), it is darker than the portion 22 of the field of view of the front monitoring, and only the sun 24 is appropriate. It is configured to appear with brightness. When mounted on the vehicle A described above, the lower area 23 corresponds to the bonnet B portion of the front visual field, and thus does not affect the monitoring of the front visual field. Further, the upper area 11 of the screen 20 is darker than the visual field portion 22 because the blocking portion 4 is provided to block the direct sunlight from the sun. In FIG. 3, the upper area 21 and the lower area 23 of the screen 20 are cut horizontally, but for the purpose of preventing the dazzling of sunlight, the boundary may be determined as necessary. It may be a curved or discontinuous area.

  If the first reflecting member 3 is a separate member from the bonnet B, the trajectory of the orbit 25 drawn by the sun becomes straightforward, and post-processing of the image becomes easy. The blocking unit 4 for preventing direct light from the sun from irradiating the sky part may be, for example, a hood attached to the upper part of the front surface of the imaging camera K. Alternatively, a partition may be placed in front of and above the imaging camera K. In this case, the light may be shielded integrally with the lens barrel. Further, the illuminance on the imaging surface is set to an appropriate value by appropriately changing the position where the light reducing means is provided, the area of the light reducing means, and the amount of light reduction depending on the shape of the bonnet B (tilt angle, curvature, etc.) Can do.

[Second Embodiment]
FIG. 4 shows that in the above-described imaging camera K, a wide-angle lens (imaging optical system) for front and rear monitoring applications such as white line detection and a drive recorder is formed with a substantially point image of sunlight, and from that position coordinate and intensity at that time 2 is a cross-sectional view of the optical system of the composite optical system 11 according to the second embodiment in which the weather condition of the sun and the relative position coordinates of the sun with respect to the imaging camera K are detected. The composite optical system 11 includes an imaging optical system 12, a first reflecting member 13 disposed in front of the imaging optical system 12 and below the optical axis, and having a reflecting surface facing upward. The second reflecting member 14 is disposed above the optical axis of the imaging optical system 12 and has a reflecting surface facing downward. The second reflecting member 14 is a convex mirror that is arranged so that the optical axis finally passes through the position of the substantially entrance pupil of the imaging optical system 2. The second reflecting member 14 is directly from the sun by the first reflecting member 13. Optical that reflects and reflects light, and further reflects by the second reflecting member 14 and is guided to the entrance pupil of the imaging optical system 12 to form a sun image on the upper surface of the field of view of the imaging surface I, that is, in the sky. It is a system. In addition, since the second reflecting member 14 is disposed in front of and above the imaging optical system 12, it blocks direct sunlight (not shown) incident from the upper part of the imaging optical system 12. It also has a function to do.

The second reflecting member 14 is made of the same material as the high-density density filter having a density of 4 or higher that considerably suppresses the transmission of sunlight. The sensitivity of the image pickup device that detects the image formed by the image pickup optical system 12 without returning through the second reflection member 14 can be reduced to be lower than the element sensitivity. In this composite optical system 11, the surface reflected light of the second reflecting member (planar mirror, convex mirror, concave mirror) 14 is guided to the imaging optical system 12, but reflection reducing means (antireflection prevention) is used to reduce the surface reflected light. It is desirable to reduce the reflectance at a predetermined wavelength to about 1 × 10 ⁻⁴ (0.01%).

Further, when the reflectance is higher than this, there is a possibility that the amount of light incident on the imaging optical system 12 is too large. In this case, the first reflecting member 13 is provided with a reflection reducing means, and further, the imaging optical system 12 is used. The light reducing means 15 is provided on the optical path of the object side surface of the first lens 12a (for example, the upper part of the lens surface closest to the object side of the first lens 12a) (for example, a substance having a light reducing effect is deposited). Therefore, it is desirable that the total transmittance of the detection area of the sun image in the image sensor is approximately 1 × 10 ⁻⁴ (0.01%).

Actually, it is difficult to suppress the reflectance to about 1 × 10 ⁻⁴ (0.01%) with only one reflecting surface, for example, the second reflecting member 14, and the first and second reflecting members 13, It is desirable that both the surface reflectances of 14 are suppressed to approximately 1 × 10 ⁻² (1%) and the total transmittance is approximately 1 × 10 ⁻⁴ (0.01%). In this case, the first reflecting member 13 is also made of a high-density density filter material with a density of 4 or higher that significantly suppresses the transmission of sunlight. Only the sunlight reflected by the respective surfaces of the first reflecting member 13 and the second reflecting member 14 is guided to the imaging optical system 12 so as to be less than the element sensitivity of the optical system 12. Furthermore, if the amount of light reaching the imaging surface I is more than about 1 × 10 ⁻⁴ (0.01%) even with two reflections and there is a problem with the balance of illuminance, as described above, the surface of the optical path of the object side of the first lens 12a of the imaging optical system 12 (the upper portion of the lens), the provided light reducing means 15, the total transmittance of approximately 1 × 10 ^-4 (0.01%) on the extent To be. It is desirable that this dimming means be applied to the first reflecting member 13 as much as possible in order to reduce thermal damage to the optical system after the second reflecting member 14. Note that the first reflecting member 14 and the imaging optical system 12 are prevented in order to prevent a light beam reflected once by the first reflecting member 13 from directly entering the imaging optical system 12 and forming an image on the imaging surface I. In the middle of this, it is desirable to dispose the light shielding plate 16 in the lower part of the imaging optical system 12 immediately before the lens.

  More specifically, as the imaging optical system 12, in the second embodiment, the example described in Japanese Patent Publication No. 51-14017 is proportionally reduced to a predetermined focal length, and the focal length f1 = 2.55 mm, A lens having F / 4, an incident angle of 2ω = 180 degrees, and a maximum image height ymax = 3.86 mm was used. The first reflecting member 13 for detecting the sunlight guides a convex hyperboloid having a focal length f2 = −67.000 mm and K = 7.1111 with respect to the optical axis of the imaging optical system 12 by 80 degrees. The position of the second focal point of the hyperboloid described above is reflected by the second reflecting member 14 disposed in the horizontal direction at a distance of 57.75 mm from the apex of the first reflecting member 13 and turned back by 23.66 mm. This is roughly matched with the position of the entrance pupil on the optical axis of the imaging optical system 12. In FIG. 4, optical paths are shown for typical light beams L <b> 6 to L <b> 9 with different levels of the sun's south and middle altitudes.

FIG. 5 shows a screen 30 in which an image on the imaging surface I is schematically represented as a video image. In this case as well, a vertically long screen is used. In this 2nd Embodiment, the place where a solar image is formed differs compared with the case of the above-mentioned 1st Embodiment. In Japan, when the imaging optical system 12 is fixed in the south direction, the position of the sun 34 at a certain point in front of the south and middle is shown assuming that the sun travels on the orbit 35. The sun image detection area is the upper area 33 of the screen 30. Further, as described above, the surface of the first lens 12a of the imaging optical system 12 is provided with the light reducing means 15 for suppressing the transmittance only in the vicinity of the sunlight transmitting portion, and the sun image detection area. Since the total transmittance of 33 is reduced to about 1 × 10 ⁻⁴ , it is darker than the portion 32 of the field of view of the front monitoring so that only the sun 34 can be captured with appropriate brightness. It is configured. The lower area 31 of the screen 30 is dark because the light reflected from the first reflecting member 13 is blocked by the light shielding plate 16. In FIG. 5, the upper area 33 and the lower area 31 of the screen 30 are cut horizontally, but this is for the purpose of preventing the illusion of sunlight. It may be curved or discontinuous.

  FIG. 6 shows a configuration of an imaging system 40 that is mounted on, for example, a vehicle and captures a situation in front of the vehicle through a window W as an example of the optical apparatus having the composite optical system 1 shown in the first embodiment. ing. The photographing system 40 discriminates the sun image from the image recording device 44 arranged in the vehicle divided by the window W as described above and the image generated by the image recording device 44, and the illuminance ( (Brightness) is measured, and environmental conditions inside and outside the vehicle are analyzed together with other information not described such as time, position, direction, etc., and a detection unit 45 that emits a control signal is included. Here, the image recording device 44 is output from the composite optical system 1 for measuring the sun position and intensity described above, the image sensor 41 that detects an image formed by the composite optical system 1, and the image sensor 41. An image processing unit 42 that generates an image of a subject from the electrical signal and an image storage unit 43 that stores an image generated by the image processing unit 42, and the image generated by the image processing unit 42 is detected. The unit 45 is also configured to be output. As described above, the composite optical system 1 includes the imaging optical system 2 that images the front of the vehicle and the first reflecting member 3 that reflects sunlight and guides it to the imaging optical system 2. A part of the bonnet of the vehicle can be used as the reflecting member 3. It goes without saying that the first reflecting member 3 may be disposed close to the imaging optical system 2 in the window shield W.

  According to the imaging system 40 having such a configuration, for example, when the detection unit 45 determines that the sunlight position is high and the illuminance is high from the sun image detected by the imaging device 41 via the composite optical system 1. Is configured to perform control for suppressing the transmittance of the window, so that a safer driving environment can be obtained. Of course, the same applies even when the composite optical system 11 according to the second embodiment is used in the photographing system 40.

  In the above embodiments, a specific wide-angle lens is used. However, a lens having an arbitrary specification may be selected based on a necessary viewing angle and the resolving power of the object, and the present invention can be implemented regardless of the selection of the lens. .

It is explanatory drawing for demonstrating the structure which combines and detects the detection of sunlight with the front monitoring camera mounted in the vehicle. It is a lens block diagram for demonstrating the structure of the compound optical system which concerns on 1st Embodiment. It is explanatory drawing which shows the example of the image on the imaging surface in the said 1st Embodiment. It is a lens block diagram for demonstrating the structure of the compound optical system which concerns on 2nd Embodiment. It is explanatory drawing which shows the example of the image on the imaging surface in the said 2nd Embodiment. It is a block diagram for demonstrating the structure of the imaging | photography system which has the above-mentioned compound optical system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Compound optical system 2,12 Image pick-up optical system 3,13 1st reflection member 4 Blocking part 14 2nd reflection member (blocking part) 5,15 Dimming means 40 Imaging system (optical apparatus) 41 Imaging element 45 Detector

Claims (11)

An imaging optical system;
A first reflection that reflects light from the sun by a reflecting surface disposed in front of the imaging optical system and below the optical axis of the imaging optical system and guides it to the entrance pupil of the imaging optical system. Members,
And a dimming unit disposed on an optical path connecting the imaging optical system, the first reflecting member, and the sun, and dimming the light reflected by the first reflecting member.   The composite optical system according to claim 1, wherein the first reflecting member is a convex mirror.   The composite optical system according to claim 1, further comprising a blocking unit configured to block light directly incident on the imaging optical system from light from the sun.   The composite optical system according to any one of claims 1 to 3, wherein the reflective surface of the first reflective member has a reflectance of normal incident light of 5% or less.   The light that is disposed above the optical axis of the imaging optical system and on the optical path between the first reflecting member and the imaging optical system and that is reflected by the first reflecting member is directed downward. 5. The composite optical system according to claim 1, further comprising a second reflecting member that is reflected by the reflecting surface and led to the entrance pupil of the imaging optical system.   The said 2nd reflection member is arrange | positioned so that the light which directly injects into the said imaging optical system among the lights from the sun for at least considerable time at the time of sunlight may be interrupted | blocked. Compound optical system.   At least one of the reflecting members arranged in front of the imaging optical system is a substantially rotating hyperboloid having a convex reflecting surface, and the first focal point of the hyperboloid is the imaging optical system. 2. The optical system according to claim 1, wherein the second focal point or the image of the second focal point is arranged so as to substantially coincide with the entrance pupil of the imaging optical system at least when the light is observed. The composite optical system as described in any one of -6.   All the reflection members arranged in front of the imaging optical system are surface mirrors made of a member that absorbs a considerable amount of light, and the reflection surface is a light beam having a specific wavelength, The composite optical system according to any one of claims 1 to 7, wherein reflection reducing means for reducing the reflectance of a light beam incident perpendicularly to the reflecting surface to 3% or less is formed. The imaging optical system is attached to a vehicle,
The composite optical system according to claim 1, wherein the first reflecting member is a part of a vehicle body of the vehicle. An imaging optical system;
A composite that includes a dimming unit that emits light from the sun and is reflected on the first reflecting member in front of the imaging optical system and passes through the entrance pupil, and dimmes the light. Optical system. The composite optical system according to any one of claims 1 to 10,
An image sensor for detecting an image formed by the composite optical system;
An optical device comprising: a detection unit that detects at least one of a position of the sun and an intensity of the light from the image of the light from the sun among the images detected by the imaging element.

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