JP2009224192A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of imaging a still image or a moving image with high sensitivity and at a high speed. <P>SOLUTION: The imaging apparatus includes a cylindrical lens, a cylindrical vacuum container which is arranged and installed coaxially with the cylindrical lens and keeps the interior vacuum, a cylindrical photoelectric conversion part which is arranged and installed coaxially with the vacuum container inside the vacuum container and accumulates an electric charge generated by an incident light made incident through the lens and the vacuum container, and an electron emitting source which is arranged and installed coaxially with the vacuum container inside the vacuum container and emits electrons to an inner peripheral face of the photoelectric conversion part in order to read out the electric charge accumulated at the photoelectric conversion part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus having a field angle of 360 degrees and capable of capturing a still image or a moving image with high sensitivity.

  Conventionally, there has been proposed an imaging apparatus that captures a still image or a moving image having a field angle of 180 degrees or more using a wide-angle lens.

  Since it is difficult to realize such a wide-angle image simply by using a wide-angle lens, for example, an image obtained by disposing a plurality of cameras (imaging devices) and obtained by separate imaging devices. An imaging technique for connecting the two is conceivable.

In addition, by using a special lens without using a plurality of imaging devices in this way, a method (for example, Patent Document 1) or a camera (imaging device) that combines captured images into one image is used. A technique (for example, Patent Document 2) that obtains a wide-angle image by mechanical rotation has been proposed.
JP 2007-116395 A JP 2007-271690 A

  As described above, various image pickup apparatuses have been proposed in order to obtain wide-angle images, but each has the following problems.

  In the method using a plurality of cameras (imaging devices), there is a problem that an increase in cost cannot be avoided. For this reason, it is required to reduce the number of cameras (imaging devices), and it has been desired to realize it by one.

  In the method using a single camera (imaging device), a mechanism for mechanically rotating the camera (imaging device) is required, and thus a reduction in image accuracy has been a problem. In particular, when the subject moves at a high speed, it is difficult to rotate the camera at a high speed, and thus imaging is extremely difficult. For this reason, it has been desired not to use an operation such as a rotation mechanism.

  The technique for capturing an image with a field angle of 360 degrees using a special lens has a problem that electronic processing such as image processing becomes complicated. In particular, when the subject moves, it is necessary to perform image processing simultaneously with imaging. For this reason, it has been desired to simplify processes such as image processing as much as possible.

In addition, in the case of imaging with a general camera, especially for consumer use, if the sensitivity is insufficient, the subject is compensated for the lack of sensitivity by illuminating the subject with a flash lamp or by increasing the exposure time. . However, when imaging with a wide angle of view, it is necessary to illuminate the subject evenly, so that there is a problem that a high-power lighting device is required or that instantaneous imaging is difficult.
Furthermore, when taking a distant view with a consumer camera, there is a problem that the illumination is insufficient and the illuminance is insufficient, resulting in a noisy image.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an imaging apparatus that has a field angle of 360 degrees and can capture a still image or a moving image with high sensitivity and high speed.

  An imaging device according to one aspect of the present invention includes a cylindrical lens, a cylindrical vacuum container that is disposed coaxially with the cylindrical lens and holds the inside in a vacuum, and the vacuum inside the vacuum container. A cylindrical photoelectric conversion unit disposed coaxially with the container and storing charges generated by incident light incident through the lens and the vacuum container; and coaxially with the vacuum container inside the vacuum container. And an electron emission source that emits electrons for reading out electric charges accumulated in the photoelectric conversion unit to an inner peripheral surface of the photoelectric conversion unit.

  The electron emission source may be an electron gun disposed on the central axis of the vacuum vessel at least on one end side of the vacuum vessel.

  The electron emission source may be a plurality of cold cathodes arranged in a matrix on a circumferential surface facing the inner circumferential surface of the photoelectric conversion unit.

  Further, the photoelectric conversion unit may include an amorphous selenium film.

  According to the present invention, it is possible to provide a specific effect that an imaging apparatus having a field angle of 360 degrees and capable of capturing a still image or a moving image with high sensitivity and high speed can be provided.

  Hereinafter, embodiments to which the imaging apparatus of the present invention is applied will be described.

[Embodiment 1]
FIG. 1 is a perspective view illustrating a configuration of the imaging apparatus according to the first embodiment.

  The imaging device 10 according to the first embodiment includes a cylindrical lens 11, a cylindrical vacuum container 12, a cylindrical photoelectric conversion unit 13, and electron guns 14 and 15. These are all arranged coaxially with the central axis l of the cylindrical lens 11.

  The lens 11 has a cylindrical shape, and is configured such that the thickness of the cross section in the radial direction (the width of the cross section 11a) is thickest at the midpoint in the central axis direction, and the cross section 11a has a rhombus shape. . The lens 11 is made of glass and is an optical member that collects light incident from the outside in the radial direction and guides it to the photoelectric conversion unit 13 in the vacuum vessel 12. The lens 11 is configured to collect light incident from the entire circumferential direction (360 ° direction in the circumferential direction) and form an image on the photoelectric conversion unit 13.

  The vacuum vessel 12 is sealed with a photoelectric conversion unit 13 disposed therein and electron guns 14 and 15 disposed on the upper and lower ends. The vacuum vessel 12 is a cylindrical glass vessel, and is fixed by a jig (not shown) so as to be arranged coaxially with the lens 11.

  The photoelectric conversion unit 13 is a photoelectric conversion unit in which a photoelectric conversion film is formed on a transparent and flat resin substrate, and is in a state of being in contact with the inner surface of the vacuum vessel 12 in a state of being rounded into a cylindrical shape. It is fixed with. The photoelectric conversion film is a film that generates electron-hole pairs by using the energy of incident light. Here, a HARP (High-Gain Avalanche Rushing amorphous Photoconductor) film is used.

  The HARP film uses amorphous selenium that can be manufactured at a low temperature, and an ultrasensitive photoelectric conversion film can be realized by using avalanche multiplication. The use of the HARP film eliminates the need for auxiliary illumination to compensate for the lack of sensitivity over the entire circumferential direction, and enables imaging in the entire circumferential direction even when extremely dark, particularly at night. Further, since it is formed on a resin substrate, a HARP film that can be formed at a low temperature is suitable as a photoelectric conversion film.

  Here, as for the dimensions of each part, for example, the lens 11 has a length in the central axis direction of 200 mm, an inner diameter of the upper end and the lower end of 150 mm, and a thickness of the cross section 11a of 5 to 15 mm. The vacuum container 12 has a length in the central axis direction of 200 mm, a diameter of 100 mm, and a thickness of 2 mm. The photoelectric conversion unit 13 has a length in the central axis direction of 50 mm and a thickness of 1 mm. The electron guns 14 and 15 have a length in the central axis direction of 100 mm and a diameter of 20 mm, and the length in the central axis direction protruding into the vacuum vessel 12 is 40 mm.

  The photoelectric conversion unit 13 is connected to a circuit for detecting an imaging signal read by the electron beams emitted from the electron guns 14 and 15. For convenience of explanation, FIG. 1 is omitted and FIG. 2 is used. Will be described later.

  FIG. 2 is a diagram illustrating a cross-sectional structure of the photoelectric conversion unit 13 of the imaging device according to the first embodiment. The photoelectric conversion unit 13 forms a transparent electrode 13B made of ITO (Indium Tin Oxide) on a resin substrate 13A, and further laminates a hole injection blocking layer 13C, an amorphous selenium film 13D, and an electron injection blocking layer 13E. It has the structure.

  Among these, the hole injection blocking layer 13C, the amorphous selenium film 13D, and the electron injection blocking layer 13E constitute a HARP film. Since the HARP film can be formed at a low temperature, it is suitable for a photoelectric conversion film formed on a substrate having a relatively low heat resistance such as a resin, and is a material that can ensure the uniformity of electron emission. Suitable for ultra-sensitive imaging devices.

  The transparent electrode 13B can be formed on the surface of the substrate 13A by spin coating. A signal readout circuit 16 is connected to the transparent electrode 13B, and when electric charges generated in the photoelectric conversion unit 13 are read out by the electron guns 14 and 15, the current value is detected by the signal readout circuit 16 to represent an image. An imaging signal is obtained.

The hole injection blocking layer 13C is made of cerium oxide (CeO ₂ ) having a thickness of 10 to 30 nm, and is formed on the transparent electrode 13B by a vacuum deposition method.

  The amorphous selenium film 13D is formed by a vacuum deposition method as an amorphous semiconductor layer (a-Se) whose main raw material is selenium (Se) having a thickness of 2 to 50 μm.

The electron injection blocking layer 13E is deposited as an antimony trisulfide (Sb ₂ S ₃ ) layer having a thickness of 0.1 μm, for example, in an argon (Ar) gas atmosphere at a pressure of 0.1 to 0.4 Torr.

  Thus, the HARP film can be formed by a vacuum deposition method. The substrate 13A on which the HARP film is formed is plate-like, but after the HARP film is formed, the substrate 13A is rounded in accordance with the inner diameter of the vacuum container 12 to be disposed in the vacuum container 12, and is a cylindrical photoelectric conversion unit. 13 is produced.

  HARP film realizes extremely high quality image quality with ultra-high sensitivity, high resolution, and low afterimage by suppressing the image defect phenomenon by applying a high voltage that causes charge avalanche multiplication within the photoelectric conversion film. It is a photoelectric conversion film that can be used.

  The electron guns 14 and 15 are electron guns arranged coaxially on the central axis l of the lens 11, and have a deflection yoke similar to the electron gun used for the cathode ray tube, and are configured to be able to scan the irradiated electron beam. Has been. The electron guns 14 and 15 are sealed at both ends of the vacuum container 12 so that the electron emission portions are located in the vacuum space.

  The electron guns 14 and 15 include a hot cathode that generates thermoelectrons or a cold cathode that extracts electrons by an electric field. By driving and controlling a deflection yoke (not shown), an emitted electron beam is disposed in the vacuum space 12. It is driven so as to scan the inner peripheral surface of the cylindrical photoelectric conversion unit 13. The scanning of the electron beam will be described later with reference to FIG.

In order to scan the inner peripheral surface of the photoelectric conversion unit 13, the electron guns 14 and 15 are arranged at positions shifted from the photoelectric conversion unit 13 in the central axis direction, and perform wide-angle scanning. In the first embodiment, since the electron guns 14 and 15 are disposed above and below the cylindrical photoelectric conversion unit 13, the number of pixels is smaller than that of an imaging device including only one of the electron guns 14 and 15. It can be increased by a factor of two.
FIG. 3 is a partial perspective view for explaining the operation principle of the imaging apparatus according to the first embodiment. This drawing shows a part of the entire configuration shown in FIG. 1 for convenience of explaining the locus of incident light or electron beam.

  The lens 11 receives light reflected from the subject or light emitted from the subject. In FIG. 3, only light that enters from the left direction in the drawing is indicated by an arrow, but actually light enters from the entire circumferential direction of the lens 11 (direction of 360 degrees in the circumferential direction). Thereby, an angle of view of 360 degrees is realized.

  Incident light that passes through the lens 11 is collected by a biconvex lens having a rhombus-shaped cross section 11 a, passes through the glass vacuum vessel 12, and forms an image on the amorphous selenium film of the photoelectric conversion unit 13. By irradiation with incident light, electron-hole pairs are generated in the HARP film.

  The electron beam 14 a emitted from the electron gun 14 is first scanned along the inner periphery 13 a at the upper end of the photoelectric conversion unit 13 by driving and controlling a deflection yoke (not shown). At this time, the scanning angle α (scanning angle in a plane including the diameter of the cylindrical photoelectric conversion unit 13) is set to a wide angle of 110 degrees, for example.

  By driving and controlling the deflection yoke, the electron gun 14 a emitted from the electron gun 14 spirals while drawing a circle along the inner peripheral surface from the inner periphery 13 a at the upper end of the photoelectric conversion unit 13 to the inner periphery 13 b at the center. It scans so that it may fall in a shape. This spiral scan is repeated at a predetermined cycle.

  Similarly, the electron beam 15 a emitted from the electron gun 15 is first scanned along the inner circumference 13 c at the lower end of the photoelectric conversion unit 13 by driving and controlling a deflection yoke (not shown). The scanning angle β at this time (scanning angle in a plane including the diameter of the cylindrical photoelectric conversion unit 13) is set to a wide angle of 110 degrees, for example.

  By driving and controlling the deflection yoke, the electron gun 15a emitted from the electron gun 15 spirals while drawing a circle along the inner peripheral surface from the inner periphery 13c at the lower end of the photoelectric conversion unit 13 to the inner periphery 13b at the center. It is scanned so as to rise. This spiral scan is repeated at a predetermined cycle.

  By scanning the electron beams 14 a and 15 a emitted from the electron guns 14 and 15 in this way, the charges generated on the HARP film of the photoelectric conversion unit 13 are read out. By detecting the read current by the signal readout circuit 16 shown in FIG. 2, an imaging signal representing an image with an angle of view of 360 degrees can be obtained.

  According to the imaging device of the first embodiment, the cylindrical lens 11, the vacuum container 12, and the photoelectric conversion unit 13 that are arranged coaxially are used to obtain light that is incident from the entire circumference of the lens 11. The captured image can be taken. As a result, an image with an angle of view of 360 degrees can be obtained at high speed without requiring special image processing (for example, joining of a plurality of images) as in the case of normal still images and moving images.

  In the first embodiment, since the HARP film is used for the photoelectric conversion unit 13, it is possible to take an image with extremely high sensitivity, and to capture a still image or a moving image with an angle of view of 360 degrees at high speed and with high sensitivity. An apparatus can be provided.

  In a general imaging device that does not use an ultra-sensitive photoelectric conversion film such as a HARP film, it is necessary to illuminate the subject evenly, so that a high-power lighting device is used. There is a problem that it is necessary and imaging at high speed is difficult. For this reason, it is desirable not to use auxiliary light when performing wide-angle shooting.

  In this regard, according to the imaging apparatus using the HARP film as the photoelectric conversion film as in the imaging apparatus of the first embodiment, it is possible to perform ultra-high sensitivity imaging without using auxiliary light even when the illuminance is extremely low such as at night. In addition, it is possible to provide an imaging apparatus capable of capturing a still image or a moving image with a field angle of 360 degrees at high speed and with ultra-high sensitivity.

  In the above description, the form in which the focal length of the lens 11 is fixed has been described. However, in order to adjust the focal length, a lens that can change the focal length steplessly may be used. The lenses may be exchanged with different lenses (other focal lengths are fixed). In the former case, the lens configuration is more complicated than in the latter case.

  In the above description, the cross section 11a of the lens 11 has a rhombus shape. However, the cross section shape is not limited to a rhombus, and any lens that can image incident light on the photoelectric conversion unit 13 may be used. Alternatively, a biconvex lens or a single convex lens having a cross-section or other cross-sectional shape lens may be used.

  Moreover, although the form which uses a HARP film | membrane as a photoelectric converting film contained in the photoelectric conversion part 13 was demonstrated above, you may use the photoelectric converting film produced with the silicon-type or chalcogenide-type material.

In the above, an embodiment using an electron gun including a hot cathode as the electron guns 14 and 15 has been described. However, the configuration of the electron gun is not limited to that using a hot cathode, and a needle-like Spindt-type cold cathode cathode is used. What is included may be used.
In the above description, the configuration that can cope with the increase in the number of pixels by using the pair of electron guns 14 and 15 above and below the photoelectric conversion unit 13 has been described. However, the electron gun is either one of the top and bottom (that is, the electron gun 14). Or any one of 15). In this case, one electron gun scans from the inner circumference 13a side at the upper end of the photoelectric conversion unit 13 to the inner circumference 13c side at the lower end.

[Embodiment 2]
FIG. 4 is a partial perspective view for explaining the operation principle of the imaging apparatus 20 according to the second embodiment. The imaging apparatus according to the second embodiment is characterized in that an electron beam source 24 in the form of an array in which cold cathodes are arranged in a matrix is used as an electron emission source instead of the electron guns 14 and 15 in the first embodiment. Different from Form 1. Since the other components are all in accordance with the imaging device 10 of the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

  For the sake of convenience of explanation, the lens 11 is omitted in FIG. 4, but actually, it is disposed outside the vacuum vessel 12 similarly to the imaging device 10 of Embodiment 1, and the vacuum vessel 12, the photoelectric conversion unit 13, The electron beam source 24 is disposed coaxially with the central axis l of the lens 11.

  The electron beam source 24 is a cylindrical electron emission source including a plurality of cold cathodes arranged in a matrix on a circumferential surface facing the inner circumferential surface of the photoelectric conversion unit 13. As described above, since the electron beam source 24 is arranged coaxially with the central axis l of the lens 11, the vacuum vessel 12 and the photoelectric conversion unit 13 are arranged coaxially with a jig (not shown). Fixed.

  FIG. 5 is a diagram illustrating a cross-sectional structure of the electron beam source 24 of the imaging apparatus 20 according to the second embodiment. The electron beam source 24 of Embodiment 2 is produced by rolling a plurality of cold cathodes arranged in a matrix on a flat substrate, like the photoelectric conversion film 13, into a cylindrical shape, FIG. 5 shows a partial cross section of the flat plate-like electron beam source 24 before being rounded into a cylindrical shape.

  As shown in FIG. 5, the electron beam source 24 has a flat structure in which a lower metal electrode 24B, an insulating layer 24C, an electron acceleration layer 24D, and an upper metal electrode 24E are stacked on a resin film substrate 24A. Have.

  The substrate 24A is a substrate made of a resin film, and needs to be made of a flexible material in order to be disposed in a cylindrical shape inside the cylindrical photoelectric conversion unit 13. The substrate 24A is composed of, for example, a polyimide film having a thickness of 200 μm.

  The lower metal electrode 24B is a metal electrode formed on the substrate 24, and functions as a cathode that emits an electron beam. The lower metal electrode 24B is composed of, for example, a thin film electrode made of aluminum (Al), tantalum (Ta), and molybdenum (Mo) having a thickness of 0.2 μm.

The insulating layer 24C is an insulating layer for insulating the lower metal electrode 24B and the upper metal electrode 24E. For example, tantalum pentoxide (Ta ₂ O ₅ ), silicon nitride (SiN) having a thickness of 0.5 μm, or It is composed of alumina (Al ₂ O ₃ ).

  The electron acceleration layer 24D is a layer for accelerating electrons between the lower metal electrode 24B and the upper metal electrode 24E, and is made of, for example, zinc sulfide (ZnS) having a thickness of 0.5 μm.

  The upper metal electrode 24E is an anode electrode for forming a potential difference for accelerating electrons with the lower metal electrode 24B. Since the upper metal electrode 24E transmits electrons by tunneling, the thickness of the upper metal electrode 24E needs to be set to be equal to or less than the mean free path of electrons. The upper metal electrode 24E is composed of, for example, a thin film electrode made of gold (Au) having a thickness of 10 nm.

  The lower metal electrode 24B and the upper metal electrode 24E are stripe-shaped electrodes that constitute a scanning line and a selection line, respectively, and are arranged so as to intersect in a matrix in a plan view. A pulse generating power source 27 is connected to the lower metal electrode 24B and the upper metal electrode 24E.

  The pulse generation power source 27 is configured to be able to apply a pulse voltage by selecting an arbitrary electrode from the plurality of lower metal electrodes 24B and the upper metal electrode 24E, and the selected lower electrode 24B and the selected upper electrode 24E. The electron beam 24a is emitted from the lower metal electrode 24B at the point where the two intersect.

  Since the electron beam source 24 is configured to emit the electron beam 24a radially outward in a state of being rounded into a cylindrical shape, a desired lower metal electrode 24B is selected by selecting a scanning line and a selection line. Can emit an electron beam 24 a to the inner peripheral surface of the photoelectric conversion unit 13.

  The electron beam 24 a emitted from the electron beam source 24 is scanned along the inner periphery 13 a at the upper end of the photoelectric conversion unit 13 and draws a circle along the inner peripheral surface up to the inner periphery 13 c at the lower end of the photoelectric conversion unit 13. However, it is scanned so as to descend spirally. This spiral scan is repeated at a predetermined cycle.

  By scanning the electron beam 24a emitted from the electron beam source 24 in this way, the charge generated on the HARP film of the photoelectric conversion unit 13 is read out. The read current is detected by the signal readout circuit 16 as in the imaging apparatus of the first embodiment, and an imaging signal representing an image with a field angle of 360 degrees is obtained.

  According to the imaging device of the second embodiment, by using the cylindrical lens 11, the vacuum container 12, and the photoelectric conversion unit 13 that are coaxially arranged, the light is incident from the entire circumference of the lens 11. The captured image can be taken. As a result, an image with an angle of view of 360 degrees can be obtained at high speed without requiring special image processing (for example, joining of a plurality of images) as in the case of normal still images and moving images.

  In the second embodiment, since the HARP film is used for the photoelectric conversion unit 13, it is possible to take an image with extremely high sensitivity, and to capture a still image or a moving image with an angle of view of 360 degrees at high speed and with high sensitivity. An apparatus can be provided.

  In the above description, the electron beam source 24 has been described using an electron emission source produced by rolling a resin film substrate on which cold cathodes arranged in a matrix are formed into a cylindrical shape. The cylindrical electron beam source 24 has an advantage that the position of the electron beam 24a can be accurately determined. However, the configuration of the electron emission source is not limited to this, and a cold cathode such as a Spindt type, a carbon nanotube, or a graphite nanofiber may be used.

  The substrate 24A used for the electron beam source 24 is not limited to a resin film, and a flexible glass substrate that can be rolled into a cylindrical shape may be used.

  The imaging device according to the exemplary embodiment of the present invention has been described above, but the present invention is not limited to the specifically disclosed embodiment, and does not depart from the scope of the claims. Various modifications and changes are possible.

1 is a perspective view illustrating a configuration of an imaging device according to Embodiment 1. FIG. 3 is a diagram illustrating a cross-sectional structure of a photoelectric conversion unit 13 of the imaging device according to Embodiment 1. FIG. 4 is a partial perspective view for explaining an operation principle of the imaging apparatus according to Embodiment 1. FIG. FIG. 6 is a partial perspective view for explaining an operation principle of the imaging device 20 according to the second embodiment. It is a figure which shows the cross-section of the electron beam source 24 of the imaging device 20 of Embodiment 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 20 Image pick-up device 11 Lens 11a Section 12 Vacuum container 13 Photoelectric conversion part 13a Inner periphery 13b Upper inner periphery 13c Lower inner periphery 13A Substrate 13B Transparent electrode 13C Hole injection blocking layer 13D Amorphous selenium film 13E Electron injection blocking Layers 14 and 15 Electron gun 16 Signal readout circuit 24 Electron beam source 24A Substrate 24B Lower metal electrode 24C Insulating layer 24D Electron acceleration layer 24E Upper metal electrode 27 Pulse generation power source

Claims (4)

A cylindrical lens;
A cylindrical vacuum vessel disposed coaxially with the cylindrical lens and holding the inside in a vacuum;
A cylindrical photoelectric conversion unit that is arranged coaxially with the vacuum vessel inside the vacuum vessel and accumulates electric charges generated by incident light incident through the lens and the vacuum vessel;
An electron emission source that is arranged coaxially with the vacuum vessel inside the vacuum vessel and emits electrons for reading out charges accumulated in the photoelectric conversion unit to an inner peripheral surface of the photoelectric conversion unit. , Imaging device.   The imaging apparatus according to claim 1, wherein the electron emission source is an electron gun disposed on a central axis of the vacuum container at least on one end side of the vacuum container.   The imaging apparatus according to claim 1, wherein the electron emission source is a plurality of cold cathodes arranged in a matrix on a circumferential surface facing an inner circumferential surface of the photoelectric conversion unit.   The imaging device according to any one of claims 1 to 3, wherein the photoelectric conversion unit includes an amorphous selenium film.

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