JP2007028224A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of eliminating the necessity of the attaching/detaching operation of a polarizer or checking a subject image through the polarizer before photographing. <P>SOLUTION: A PBS 3 mutually separates S polarized light and P polarized light included in subject light and forms respective images of the separated S polarized light L1 and P polarized light L2 on color imaging devices 4, 5, from which two subject image signals are outputted, respectively. An image signal processing circuit 6 composes these subject image signals at a required composite ratio and the composite image signal is supplied to a view finder 7 and recorded in a recording medium. Thereby a polarizer is made unnecessary, and when the optimum composition ratio of two subject image signals based on the separated S polarized light and P polarized light is set by the image signal processing circuit 6, the check of a specific image effect caused by the separation of two polarized light components before image pickup is made unnecessary. The specific effect of a specific effect image can be changed after photographing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, and more particularly to a two-plate type imaging apparatus that captures a subject image using two imaging elements.

  2. Description of the Related Art Conventionally, there has been known a two-plate image pickup apparatus that picks up a subject image using two image pickup elements (see, for example, Patent Document 1). FIG. 5 shows a schematic configuration diagram of an example of a conventional two-plate type imaging apparatus described in Patent Document 1. In the figure, a two-plate type imaging device 20 includes a beam splitter 22 disposed on the light exit side of a photographing lens 21, and a phase difference plate 23 provided on one of the light incident surface and the two light exit surfaces of the beam splitter 22, respectively. And 24, an optical low-pass filter (LPF) 25, a dummy glass 26, two image sensors 27 and 28, an image processing circuit 29, and the like.

  In this two-plate type imaging device 20, linearly polarized light included in the light from the subject that has passed through the photographing lens 21 is converted into circularly polarized light by the phase difference plate 23, and then enters the beam splitter 22 and is made uniform by the polarizing film. The linearly polarized light included in the subject light transmitted through the polarizing film is converted into circularly polarized light when transmitted through the phase difference plate 24 and transmitted through the optical LPF 25, and the imaging element. The circularly polarized subject light incident on the light receiving surface 27 and reflected by the polarizing film passes through the dummy glass 26 and enters the light receiving surface of the image sensor 28. A double image is formed on the light receiving surface of the image sensor 27 by the birefringence of the optical LPF 25.

  The dummy glass 26 has a refractive index and a thickness so that the air-converted optical path lengths from the photographing lens 21 to the light receiving surfaces of the image sensors 27 and 28 are equal to each other. Video signals obtained by photoelectric conversion by the image pickup devices 27 and 28 are supplied to an image processing circuit 29 for image processing, and a video signal with a higher resolution and a reduced false color is generated by a single-plate image pickup device.

  In a conventional imaging apparatus, imaging is performed by intentionally limiting reflected light from a subject. This is because sunlight and general light sources (incandescent light bulbs, halogen lamps, mercury lamps, etc.) are indefinitely polarized light. According to the law of polarization of light due to reflection (Brewster's law), a light beam (P-polarized light) having vibration parallel to the plane formed by the incident angle and the outgoing angle of the light beam is easily transmitted, and the vertical direction A light beam having vibration (S-polarized light) is characterized by being easily reflected. In particular, as shown in FIG. 6, the angle formed between the outgoing light (reflected light) and the absorbed / refracted light is 90 ° (at this time, the incident angle of the light beam). Since the emitted light (reflected light) becomes a perfect plane wave when it becomes the Brewster angle, the polarizing plate (polarizing filter) is used to emphasize and capture the S-polarized light or P-polarized light in the reflected light. So, “Look at me” Instead of the image, because the various effects of the order to carry out the "picture-making" to the photographer's intention can be obtained.

  In this case, as shown in FIG. 7, in the case where the light incident side lens surface of the imaging lens 33 provided in front of the housing 31 of the imaging device incorporating the color imaging device 34 or the imaging lens 33 is a large aperture lens, A polarizing plate 32 is installed in the lens barrel, and this polarizing plate 32 is structured to be rotatable by a rotation mechanism (not shown) having the optical axis of incident light as a rotation axis. The image of a desired subject is picked up by sequentially rotating the screen, and the subject image that has passed through the polarizing plate 32 is viewed with a viewfinder to check whether the level of reflected light is suppressed or emphasized. The rotation of 32 is stopped and imaging is started.

  As a specific example of the effect of the polarizing plate 32, when a mannequin doll in a show window in the city is to be photographed, the street reflected and reflected on the show window cuts (absorbs) S-polarized light. Then, by aligning the polarizing plate 32 in the direction in which the P-polarized light is transmitted, the mannequin doll in the show window is emphasized, and the polarizing plate 32 is in the direction in which the P-polarized light is transmitted through the S-polarized light even in the same shooting frame (angle). In combination, the street image reflected in the show window is emphasized, the mannequin doll inside is suppressed, and the outside city including the show window is the main shooting. It is also used for photography that cuts off the reflected light from the surface of the glossy leaves and brightens the colors of flowers and birds.

JP 2000-354251 A

  However, in the conventional imaging apparatus, the polarizing plate 32 is not necessary for normal imaging, and the amount of incident light from the subject is halved as it is, so that attachment / detachment is performed as necessary. However, since the polarizing plate 32 is attached / detached using the filter attaching screw at the front end of the photographing lens 33, the attaching / detaching operation is troublesome.

  Further, in the conventional imaging apparatus, in the special effect imaging by the polarizing plate 32, imaging is performed in which the balance of the polarization components contained in the radiated light from the subject (the light beam reflected by the subject when the subject is illuminated with the light source) is lost. In addition, it is necessary to confirm whether the subject image that has passed through the polarizing plate 32 is an image that emphasizes a desired polarized light component before imaging.

  In addition, an image captured by a monitor (typically a 1 to 2 inch liquid crystal display element) provided in the image capturing apparatus can be confirmed immediately after the image capturing. However, since the brightness of the surrounding environment and the monitor are small, the image I cannot confirm details. Further, the image data obtained by the special effect imaging by the polarizing plate 32 is recorded on a recording medium such as a semiconductor memory, a hard disk memory, a magnetic tape, an optical disk or the like that is built in or detachable in the imaging apparatus, and the recording medium is stored in another recording medium. There is also a problem that the special effect by the polarizing plate cannot be changed when the image is reproduced by the apparatus.

  Furthermore, in the imaging apparatus described in Patent Document 1, a quarter wavelength plate is provided as a phase difference plate, thereby eliminating the linearly polarized light component contained in the subject to form circularly polarized light, and separating it in a balanced manner with the subsequent PBS. However, if the linearly polarized light component is included in the subject light, the separation balance is lost.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an imaging apparatus that can eliminate the need for an operation of attaching / detaching a polarizing plate and confirmation of a subject image through the polarizing plate before imaging.

  Another object of the present invention is to provide an imaging apparatus that enables confirmation of a captured image on a large monitor and changes special effects.

  Furthermore, another object of the present invention is to provide an imaging apparatus capable of optimally separating a P-polarized component and an S-polarized component contained in subject light incident on a polarization beam splitter.

  In order to achieve the above object, the image pickup apparatus of the present invention takes an image based on the first and second image signals obtained by imaging the subject light that has passed through the taking lens with the first and second image pickup elements. In a two-plate imaging apparatus that outputs an image signal, subject light that has passed through a photographing lens is converted into first subject light mainly composed of first polarized light and second subject light mainly composed of second polarized light. A polarization separation optical system that forms an image of the separated first subject light on the first image sensor and forms an image of the separated second subject light on the second image sensor; A function of combining the first image signal output from the first image sensor and the second image signal output from the second image sensor at a desired ratio and outputting as a captured image signal; An image having a function of recording the second image signal on a recording medium. And having a processing means.

  In the present invention, the subject light is separated into a first subject light mainly composed of the first polarized light and a second subject light mainly composed of the second polarized light. A composite image signal that is incident on the two image sensors and is synthesized by combining the first and second image signals output from the first image sensor and the second image sensor at a desired ratio; The first and second image signals can be recorded on a recording medium.

  In order to achieve the above object, the present invention controls the angle of the linearly polarized light component included in the subject light incident on the polarization separation optical system in the optical path between the photographing lens and the polarization separation optical system. The ½ wavelength phase difference plate is installed, and the ½ wavelength phase difference plate is configured to be rotatable about an axis parallel to the optical axis of the incident light. In the present invention, the angle of the linearly polarized light component included in the incident subject light can be controlled by the ½ wavelength phase difference plate.

  In order to achieve the above object, the present invention provides a driving means for rotating the above half-wave retardation plate by a designated rotation angle with an axis parallel to the optical axis of the incident light as a rotation axis. Then, the difference between the entire subject or a part of the light beams incident on the first and second image sensors is detected, and the driving means is controlled so as to maximize the difference between the detected light beams. And a control means for controlling the rotation of the two-wavelength phase plate.

  In the present invention, the difference between the whole or a part of the light beams incident on the first and second image sensors is detected, and the driving means is controlled so as to maximize the difference between the detected light beams. Since the two-wavelength phase plate is rotationally controlled, the first polarized light and the second polarized light can be optimally separated from the subject light by the polarization separation optical system.

  According to the present invention, the polarization separation optical system separates the subject light into the first subject light mainly composed of the first polarized light and the second subject light mainly composed of the second polarized light, respectively. A composite image signal that is incident on the first image sensor and the second image sensor, and that combines the first and second image signals output from the first image sensor and the second image sensor at a desired ratio. Therefore, any special effect image intended by the photographer can be obtained without performing the work of attaching or operating the polarizing plate, and the composition ratio at that time is set in the image processing means. This eliminates the need to check the special effect image before shooting.

  Further, according to the present invention, the first and second image signals reproduced from the recording medium are recorded on the recording medium by recording the first and second image signals on the recording medium. Since the combined image can be confirmed on a large monitor, the details of the special effect image can be confirmed as compared with the conventional case, and the first and second reproduced image signals can be confirmed even after shooting. The special effect image can be changed by changing the composition ratio.

  Furthermore, according to the present invention, since the polarized light contained in the subject light is separated by the polarization separation optical system, the polarized light component contained in the subject light can be eliminated as much as possible by using the quarter wavelength plate. Compared with the conventional apparatus that divides the light component into two parts, even if a linearly polarized light component is included in the subject light, the separation of the polarized light can be optimized without losing the separation balance.

  Further, according to the present invention, the first polarized light and the second polarized light (S) that are always optimally separated into the first and second imaging elements by rotating the half-wave retardation plate. Polarized light and P-polarized light) can be guided, and optimal S and P-polarized light can always be picked up even when the image pickup device is tilted or changed in vertical and horizontal directions. Effects such as suppression and enhancement of reflected light and improvement of image saturation can be obtained.

  Next, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram of a first embodiment of an imaging apparatus according to the present invention. In the figure, the image pickup apparatus of the present embodiment is a two-plate image pickup apparatus that picks up a subject image using two color image pickup elements 4 and 5 provided in the case 1. In addition to the color imaging elements 4 and 5, the photographing lens 2, the polarization beam splitter (PBS) 3, the image signal processing circuit 6 and the viewfinder 7 are provided.

  The PBS 3 has transmission / reflection characteristics shown in FIG. 2 by the polarizing film 3a. In the figure, a two-dot chain line I is a characteristic of S-polarized light in the reflected light reflected by the polarizing film 3a, a solid line II is a characteristic of P-polarized light in a transmitted light transmitted through the polarizing film 3a, and a solid line III is the above-mentioned reflection. The characteristic of the P-polarized light in the light and the solid line IV indicate the characteristic of the S-polarized light in the transmitted light. As can be seen from the figure, when the wavelength of incident light is in the range of 450 nm to 650 nm, the PBS 3 reflects S-polarized light and transmits P-polarized light.

  Next, the operation of the imaging apparatus according to the first embodiment having the configuration shown in FIG. 1 will be described. The radiated light (subject light) from the subject that is illuminated by the light source and reflected by the surface of the subject passes through the photographing lens 2 and enters the PBS 3 as incident light L, and the polarization film 3a described with reference to FIG. In addition, the S-polarized light L1 in the incident light L is reflected and emitted from the first main surface of the PBS 3 to form an incident image on the first color imaging device 4, and the P-polarized light L2 in the incident light L is The light passes through and emerges from the second main surface of the PBS 3 and forms an incident image on the second color imaging device 5.

  The color image sensor 4 photoelectrically converts the incident S-polarized light L 1, performs predetermined signal processing to generate a first image signal, and supplies the first image signal to the image signal processing circuit 6. On the other hand, in parallel with this, the color image sensor 5 photoelectrically converts the incident P-polarized light L2, performs predetermined signal processing to generate a second image signal, and supplies it to the image signal processing circuit 6. The image signal processing circuit 6 receives the input first image signal and second image signal via an output terminal 8 (not shown) (not shown) (built-in or removable semiconductor memory, hard disk memory, magnetic tape, optical disk) Etc.) or supplied to a personal computer (hereinafter abbreviated as a personal computer), and the synthesized image signal is obtained by synthesizing the first and second image signals at the designated synthesis ratio. An image signal is supplied to the viewfinder 7 for display. The composite image signal can be recorded on a recording medium or supplied to a personal computer.

  As a result, the viewfinder 7 displays a composite image of the two subject image signals by S-polarized light and P-polarized light. Whether or not the S-polarized light and the P-polarized light are optimally separated can be confirmed from the display image of the viewfinder 7 based on whether or not each image is visible.

  Also, two subject image signals by S-polarized light and P-polarized light output from the output terminal 8 are supplied to a personal computer, and confirmation of a subject composite image obtained by synthesizing the two subject image signals with a large monitor connected to the personal computer. If necessary, a control signal for variably controlling the composition ratio of the two subject image signals by the S-polarized light and the P-polarized light in the image signal processing circuit 6 is generated by a personal computer, and an image is input via the input terminal 9. By supplying the signal processing circuit 6, a special effect image intended by the photographer is obtained.

  As described above, according to the present embodiment, the S-polarized light and the P-polarized light included in the subject light are positively separated by the polarization separation optical system using the PBS 3, and the separated S-polarized light and the P-polarized light are used. Since the composite ratio of two subject image signals is made variable by the image signal processing circuit 6, operations for attaching and removing a polarizing plate to and from the lens surface of the photographing lens 2 and the photographing lens 2 as in a conventional imaging device Is set in the image signal processing circuit 6 by setting an optimal composition ratio of the two subject image signals by the separated S-polarized light and P-polarized light, so that the special image by separating the two polarized lights at the time of imaging is set. Confirmation of effect is unnecessary.

  Furthermore, according to the present embodiment, the captured and recorded composite image signal can be taken into a personal computer or the like and checked on a large monitor, so that details of the image can be confirmed. Furthermore, in this embodiment, unlike a conventional apparatus in which only an image signal obtained by special effect imaging using a polarizing plate is recorded on a recording medium, and polarized light components that are not used for special effect imaging are discarded. Since both the S-polarized light and the P-polarized light of the object light are not discarded, both the polarized light components are clearly separated by the PBS 3 and recorded on the recording medium. Since the special effect image is finally obtained by changing the composition ratio of the polarized light, the special effect image can be changed even after imaging.

  In the present embodiment, the light beam of the subject light is divided into two parts of the S-polarized light and the P-polarized light by the PBS 3, but the same effect can be obtained by separation by the reflective polarizing plate. Further, high-definition image data can be obtained by shifting the two color imaging devices 4 and 5 by 1/2 pixel and performing inter-pixel interpolation by the image signal processing unit 6.

(Second Embodiment)
FIG. 3 is a block diagram of a second embodiment of the imaging apparatus according to the present invention. In the figure, the same components as those in FIG. The imaging apparatus according to the second embodiment shown in FIG. 3 has a ½ wavelength (λ / 2) in order from the photographing lens 2 side in the optical path between the photographing lens 2 in the housing 1 and the light incident surface of the PBS 3. ) A retardation plate 11 and an optical low-pass filter (LPF) 12 are disposed, a polarizing plate 13 is provided on the first main surface on the output side of the PBS 3, and an optical path length is provided on the second main surface on the output side of the PBS 3. The adjustment plate 14 is characterized in that the imaging performance and operability are improved.

  The λ / 2 phase difference plate 11 is an optical component for controlling the angle of the linearly polarized light component included in the subject light (incident on the polarizing film 3a), and the attitude of the imaging device (horizontal or vertical). Depending on the condition of the reflected light from the subject (subject light), the P-polarized light and the S-polarized light included in the subject light are rotated and adjusted so as to be optimally separated. For example, in the color image sensor 4 that receives mainly S-polarized light, the rotation adjustment is performed so that the incident light beam becomes the largest. This rotation adjustment is performed while viewing the image on the viewfinder 7.

  Since the color imaging elements 4 and 5 are configured by a large number of pixels arranged at a predetermined arrangement pitch, a false signal or color moire is generated when polarized light having a high spatial frequency is incident. In order to prevent this, the optical LPF 12 cuts high frequency components in the subject image. The polarizing plate 13 is inserted between the PBS 3 and the color imaging element 4 in order to cover the characteristics of the polarizing film 3a.

  As described above, the transmission / reflection characteristics of the PBS 3 provided with the polarizing film 3a are shown in FIG. 2, and the transmitted light in the PBS 3 is mainly P-polarized light indicated by II and the S-polarized light indicated by IV. It sticks near 0% transmittance and is hardly included in the transmitted light beam, but the reflected light beam is mainly S-polarized light indicated by I, but P-polarized light is also slightly included as indicated by III. ing. In order to remove an unnecessary reflected P-polarized light component in the reflected light beam, an absorption polarizing plate 13 is installed on the first main surface side of the PBS 3 from which the reflected light beam is emitted.

  The optical path length adjusting plate 14 disposed between the color image sensor 5 and the PBS 3 is an optical component for adjusting the optical path length corresponding to the increase in the optical path length due to the polarizing plate 13 disposed on the color image sensor 4 side. It can be substituted by changing the transmission optical path length of the PBS 3.

  In this embodiment, the angle of the linearly polarized light component included in the subject light is adjusted by rotating the λ / 2 phase difference plate 11 with the optical axis direction of the incident light as the rotation axis while viewing the composite image of the viewfinder 7. Thus, the S-polarized light and the P-polarized light included in the subject light can always be optimally separated. Moreover, it has the same features as the first embodiment.

(Third embodiment)
FIG. 4 shows a configuration diagram of a third embodiment of an imaging apparatus according to the present invention. In the figure, the same components as those in FIG. The imaging apparatus of the embodiment shown in FIG. 4 is provided with a drive system including a motor 16 that rotationally drives the λ / 2 phase difference plate 11 with the optical axis direction of incident light as a rotation axis, and outputs from the color imaging elements 4 and 5. The motor 16 is rotationally controlled by the output signal of the image signal processing circuit 15 to which the image signal to be supplied is supplied, so that the S-polarized light and the P-polarized light contained in the subject light flux are optimally separated and the S-polarized light is supplied to the color imaging device 4 The p-polarized light is incident on the color image sensor 5.

  Here, the image signal processing circuit 15 is configured so that the level difference between the two subject image signals due to the S-polarized light and the P-polarized light is maximized, or the signal output of the color image sensor 4 is maximized, or The rotation of the motor 16 and the λ / 2 phase difference plate 11 is controlled so that the signal output of the color image sensor 5 is minimized.

  Here, since it is considered that the desired special effect image is obtained by synthesizing the two subject image signals of the S-polarized light and the P-polarized light at a desired synthesis ratio, only the still image recording. It is desirable that the rotation control of the / 2 phase difference plate 11 is always performed when the shutter is half-pressed or during shooting standby (the user switches the mode setting).

  According to the present embodiment, even when the image pickup apparatus is tilted or when the image is changed in the vertical and horizontal directions, the optimum S-polarized light and P-polarized light can always be optimally separated and imaged. By the way, S-polarized light and P-polarized light of subject light, which is reflected light from the subject, appears conspicuously in the case of a subject with a relatively smooth reflecting surface, and hardly occurs on a reflecting surface on which light flux is irregularly reflected. In normal imaging, the above-mentioned effects of polarized light are relatively glossy surfaces, blue water surfaces such as ponds and lakes, street windows in the streets, leaves of laurel forests such as reeds, reeds and reeds, passenger cars and walls, etc. Strongly appears on the painted surface. Therefore, in the present embodiment, in addition to the effects of the first embodiment, the reflected light is further suppressed and enhanced from the subject that is strongly influenced by the above-described polarization such as the water surface in the nature photograph etc. An effect such as improvement can be obtained.

  In the present embodiment, the λ / 2 phase difference plate 11 is rotationally controlled by rotating the motor 16 with the output signal of the image signal processing circuit 15 based on the output image signals of the color imaging elements 4 and 5. Instead of the element, a dedicated light receiving element may be provided to control the rotation of the λ / 2 phase difference plate 11.

It is a block diagram of 1st Embodiment of this invention apparatus. It is a characteristic view of an example of a polarization beam splitter. It is a block diagram of 2nd Embodiment of this invention apparatus. It is a block diagram of 3rd Embodiment of this invention apparatus. It is a block diagram of an example of the conventional imaging device. It is explanatory drawing of Brewster's law. It is a schematic block diagram of an example of the conventional imaging device which images subjecting subject light intentionally.

Explanation of symbols

1 Housing 2 Shooting Lens 3 Polarizing Beam Splitter (PBS)
4, 5 Color imaging device 6, 15 Image signal processing circuit 7 Viewfinder 11 λ / 2 phase difference plate 12 Optical low-pass filter (LPF)
13 Polarizing plate 14 Optical path length adjusting plate 16 Motor

Claims (3)

In a two-plate type image pickup apparatus that outputs a picked-up image signal based on first and second image signals obtained by picking up subject light that has passed through a photographing lens with the first and second image pickup elements,
The subject light that has passed through the photographing lens is separated into first subject light mainly composed of first polarized light and second subject light mainly composed of second polarized light, and the separated first light is separated. A polarization separation optical system that forms an image of one subject light on the first image sensor and forms an image of the separated second subject light on the second image sensor;
A function of synthesizing the first image signal output from the first image sensor and the second image signal output from the second image sensor at a desired ratio and outputting the resultant as the captured image signal And an image processing means having a function of recording each of the first and second image signals on a recording medium.   A half-wave retardation plate is installed in the optical path between the photographing lens and the polarization separation optical system to control the angle of the linearly polarized light component included in the subject light incident on the polarization separation optical system. The imaging apparatus according to claim 1, wherein the half-wave retardation plate is configured to be rotatable about an axis parallel to the optical axis of the incident light. Driving means for rotating the half-wave retardation plate by a designated rotation angle with an axis parallel to the optical axis of the incident light as a rotation axis, and a subject incident on the first and second imaging elements Control means for detecting the difference between all or part of the light flux and controlling the rotation of the half-wave phase plate by controlling the driving means so that the detected light flux difference is maximized. The imaging apparatus according to claim 2.

Images