JPS6251380A - Image pickup device - Google Patents

Abstract

PURPOSE:To improve the resolution by changing the optical axis direction of photon from a video image original line so as to make the thickness of the titled device thin thereby attaining miniaturization, light weight and large input area. CONSTITUTION:An optical fiber 1 incorporated with a fluorescent dye is a transparent rod or a transluscent rod having a square cross section made of a material such as resin, glass or ceramic. The fluorescent dye 13 arranged in the optical fiber 1 absorbs a direct ray or a scattered light and diverges it as a fluorescent light. That is, the projected light F made incident in the optical fiber 1 is absorbed by the fluorescent dye and is irradiated scatteringly in unspecified directions from the position. The fluorescent dye is prepared in the optical fiber 1 which is arranged in an array taking into the wavelength of the incident and irradiated light into consideration in this way so as to form an optical input plane to one face of a fluorescent plate 2 and to form fluorescent radiation end faces B, B'. Thus, fluorescent ray is irradiated in a direction nearly at a right angle to the incident light and the optical axis is made thin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention mainly relates to an imaging device that obtains an optical image by detecting an image primitive such as visible light or radiation.

[Technical background of the invention and its problems]

Conventionally, various methods for detecting the image primitive and visualizing it have been devised. Among them, when radiation input is visualized by an electronic method, for example, (a) it is converted into visible light using a phosphor.

(b) Ions are detected by the action of ionizing gas.

(c) Utilizing electromotive force due to the photoelectric effect of semiconductors.

(d) Utilizing photoelectron emission by a photocathode.

(e) Multiply photoelectrons using a microchannel plate.

The following methods are used, and the evaluation items for these methods are (A) Is it real-time?

(B) Is it positionally resolvable?

(C) Is there contrast?

(D) Can the input area be increased?

The following items are being considered.

By the way, there is currently no imaging device that satisfies all of the above evaluation items, and the 1-1 (imaging intensifier)-TV camera method is generally used.

However, in this method, the optical axis is long because the light is output from the surface opposite to the input surface that detects photons from the image primitive to the photoelectric conversion element, and the thickness of the device needs to be at least as thick as this optical axis. Therefore, there were problems in that the device had to be large in size and had many inconveniences in terms of operation and design. In addition, there is a practical limit to the resolution, and currently the resolution is said to be 3 lines per crane.

On the other hand, if a semiconductor is used as a solid-state image sensor in the direct light input section, it is not possible to increase the manpower area due to manufacturing constraints, it is necessary to use a lens system, and due to manufacturing constraints on the number of elements. It is difficult to achieve better resolution than the method using the above-mentioned method (1) and (1).

In addition, microchannel plates are generally used as an alternative to ■ and ■, but like I and I, T''
Since it uses the ■■ camera system, the performance of the TV camera is limited, and there is no big difference in resolution from the I/■ system.

Furthermore, it is common practice to use optical fibers and use the fiber end face as the optical input surface, but the input aperture is thick (
If this is attempted, the number of fibers will increase as is, and the configuration and electronic processing will become complicated. On the other hand, in order to reduce the number of optical fibers, mechanical scanning is required and there is a moving element, which makes it difficult to go online and complicates the overall mechanism of the device. Therefore, it is difficult to configure an imaging device with the same optical axis direction and optical fiber.

[Purpose of the invention]

The present invention has been made based on the above problem, and by changing the optical axis direction of photons from the image primitive, the device can be made thinner, smaller and lighter, and the input area can be made thicker. It is an object of the present invention to provide an imaging device that improves resolution.

[Summary of the invention]

The outline of the present invention for achieving the above object is to construct a fluorescent plate by arranging a group of optical fibers each containing a fluorescent dye in a single-layer array, and to construct a fluorescent plate by arranging a group of optical fibers each containing a fluorescent dye. A group of fluorescent-electrical conversion elements is disposed on at least one end face side of the optical fiber array to face each fiber, and further, an image of the image primitive projected onto the fluorescent plate surface is transmitted to the optical fiber array. A line scanning means is provided which can time-sequentially divide linear partial images intersecting with each other and make them sequentially incident on the fluorescent plate surface, and scan the fluorescent light amount signal outputted from each fiber end face and the line scanning means. The present invention is characterized in that an electric signal of an image of the image primitive is formed based on the combination with the signal.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which 1 is an optical fiber containing a fluorescent dye, which is a rod-shaped transparent body or semi-transparent body with a square cross section made of a material such as resin, glass, or ceramic. It is a transparent body.

The fluorescent dyes to be blended include ZnS, BaS,
Inorganic fluorophores such as CaS, as well as anthracene, sodium salicylate, fluorescein, eosin, diaminostilbene, terphenyl, benzene, pyridine, pyroic acid, pyrazine, oxazine, thiazine, thioflavin, rhodamine, imidapur, coumarin, triazole, and naphthalene. acid, imidacilone.

Carbasoles and phosphors derived from these organic substances can be used, as well as oxides and silicates of Mg, Cd, Ca, Ba, and Zn.

Phosphates, tungstates, sulfides and Mn
+ Ag, Cu, sb, pb, Fu, T I
t can be used, and the incident light,
Selection is made taking into consideration the wavelength of the emitted light.

FIG. 2 shows an optical fiber 1, which is manufactured by coating the entire surface of the optical input surface A onto which light is incident, and then polishing to remove the coating layer or masking the coating layer. Note that the light input surface A may be coated with an optical matching layer in order to reduce loss of incident light. Further, both end surfaces B and B' of the optical fiber 1 are light emitting surfaces, and the other three side surfaces A', C, and C' except for the light incidence surface A are made of CaF, Al, Sin, etc. in order to reduce transmission loss. The surface is coated with something like this to make it a reflective surface.

Reference numeral 2 denotes a fluorescent plate formed by arranging a large number of optical fibers 1 in a single layer array, and by arranging the light input surfaces A of each optical fiber 1 in the same direction, both end surfaces B and B can be simultaneously illuminated.
' becomes the light emitting surface. As shown in FIG. 3, this fluorescent plate 2 is formed by adhering adjacent optical fibers 1 to each other using an impregnation method, a film adhesive, or the like.

On both end surfaces B and B' of the fluorescent plate 2, a photoarray 3, which is a group of fluorescent-to-electrical conversion elements for converting emitted fluorescent light into an electrical signal, is arranged facing each optical fiber 1. There is.

A liquid crystal optical shutter 4 serving as a line scanning means for projecting an incident image onto the fluorescent plate 2 is disposed on the light input surface A side of the fluorescent plate 2. FIG. 4 shows a case where, for example, a TN type (twisted nematic type) liquid crystal is used as the liquid crystal optical shutter 4, and the transparent electrode 6 is aligned so that the liquid crystal molecules 5 are twisted at 90° vertically.
, 7, a liquid crystal is sealed between two glass plates 8 and 9 to form a liquid crystal cell 10. Polarizing plates 11 and 12 whose polarization directions are orthogonal to each other along with the direction of the liquid crystal molecules 5 are disposed on both outer sides of the upper and lower glass plates. In this state, the light incident on the upper polarizing plate 11 in the absence of an electric field has its polarization plane rotated by 90'' within the liquid crystal cell 10, and passes through the lower polarizing plate 12.

On the other hand, when a signal is applied to the transparent electrodes 6, 7 disposed on the two glass plates 8.9, the liquid crystal molecules 5 are arranged vertically and the optical rotation is lost. As a result, the light incident from the upper polarizing plate 11 reaches the lower polarizing plate 12 without rotating the plane of polarization, and is blocked by this polarizing plate 12. In this way, the TN type liquid crystal forms a contrast between brightness and darkness in response to the applied voltage. In the case of the TN type, the liquid crystal molecular arrangement changes with a voltage of about 2V, and the specific resistance is 19100cm.
Since it is possible to drive with low power consumption,
Time division driving is possible.

When performing optical shutter operation by selecting a specific area (pixel) on the light input surface A (light valve), one of the two transparent electrodes is arranged in a row to serve as a column electrode, and the other electrode is arranged in a row. A matrix electrode is configured such that row electrodes are used as row electrodes, and pixels are formed at intersections of these electrodes.

As shown in FIG. 5, in the apparatus of the present invention constructed in this manner, the fluorescent dye 13 blended into the optical fiber 1 absorbs direct light, dispersed light, etc. from the surroundings and emits it as fluorescent light. That is, the projected light F incident on the optical fiber 1 is exposed to the fluorescent dye 13.
It is absorbed by the area, and is dispersed and radiated from that location in unspecified directions. According to the law of total internal reflection, approximately 75% of the diverging light propagates through the optical fiber 1, and 20-30% of it is reabsorbed by the fluorescent dye 13, with other losses of 10%, leaving approximately 4% of the divergent light propagating through the optical fiber 1.
0% of the photons are propagated to the end faces B and B' of the optical fiber 1 and emitted. FIG. 6 shows the relationship between the absorbed light and the diverging light, and shows that the reabsorption of the diverging light is smaller when the peak wavelengths of the wave heights are shifted. According to Stokes' law, the unit energy of a photon of diverging light is small, that is, the wavelength of light is long. In general, in the photoelectron effect, the shorter the wavelength, the greater the electron emission, and the greater the energy of the incident light, the higher the energy at the divergent destination. When the emitted light is detected by the photoelectric element constituting the photoarray 3, it is desirable that the energy of the incident light 1 and the reflected light be higher.

By configuring the fluorescent plate 2 by arranging the optical fibers 1 containing the fluorescent dye 13 in an array in consideration of the wavelengths of the incident light and the emitted light, light is emitted onto one surface of the fluorescent plate 2. forming an input surface A, and a fluorescent emitting end surface B;
Form B'. Therefore, fluorescent light is emitted in a direction substantially perpendicular to the incident light, making it possible to reduce the thickness of the optical axis. In the case of a normal optical fiber, the light incident from the side of the fiber has few internal propagation components and is rapidly attenuated due to reflection loss, but in the case of the optical fiber 1 containing the fluorescent dye 13 of the present invention, as described above, Since a propagation component is generated and there is little reabsorption, the incident light can be effectively transmitted to the end face.

In addition, the incident image projected onto the light input surface A of the fluorescent plate 2 is formed by forming transparent electrodes in a Madrisk shape to form a liquid crystal cell 10.
Input from Note that, unlike when used as an LCD (liquid crystal display), when the I image forming pixel is used as an input window, it is desirable that the speed of the scanning electrode be low. That is, when the optical fiber 1 is constructed as the fluorescent plate 2 as described above, as shown in FIG. By connecting a large number of photoelectric elements, such as photoarrays, to the end face of the image sensor, the temporal change in the output of each photoelectric element due to the scanning electrode can be used as an image signal.

In other words, by processing the outputs of each photoelectric element simultaneously and processing them in parallel, there is an advantage that images can be reconstructed using high-speed logical operations. Not only can the reliability be improved, but also the number of scanning electrode arrays can be increased, and the resolution can be improved.

In this manner, according to the present invention, it is possible to form an electric signal of an incident image based on a combination of a fluorescent light amount signal outputted from the end face of each optical fiber 1 and a scanning signal of the liquid crystal.

Further, since both end faces B and B' of the optical fiber 1 can be used as light output ends, photoelectric elements can be distributed and arranged on both end faces, and there is no spatial interference, and the device can be made smaller and lighter.

Moreover, such a planar structure allows the light input surface to be easily coupled to a fluorescent screen, microchannel plate, etc. Further, since the glass electrodes and polarizing plates that constitute the liquid crystal cell 10 can be easily manufactured to have a large area, the area of input light can be increased as a liquid, high optical bulb. Since the fluorescent plate can also be manufactured with a large area, it is possible to obtain an imaging device with a large imaging input surface.

Although one embodiment of the present invention has been described in detail above, it can be modified as appropriate within the scope of the gist of the present invention. For example, in the above embodiment, the photoelectric elements were disposed on both end faces of the fluorescent plate, but they may be disposed on one end face.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide an imaging device that can be made smaller and lighter by reducing the thickness of the device, and can also increase the resolution by increasing the light incident area.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of the present invention, Fig. 2 is a partially cutaway perspective view showing an optical fiber, Fig. 3 is a perspective view showing a fluorescent plate, and Fig. 4 (A) is a blank view. An explanatory diagram showing the liquid crystal when an electric field is applied. Figure 5 (B) is an explanatory diagram showing the liquid crystal when a voltage is applied.
The figure is an explanatory diagram showing the flow of light through the optical fiber, and FIG. 6 is a graph showing absorbed light, emitted light, and wavelength. DESCRIPTION OF SYMBOLS 1... Optical fiber, 2... Fluorescent plate, 3... Photo array (fluorescent-electric conversion element), 4... Liquid crystal optical shutter (line scanning means), 5... Liquid crystal molecule, 13・・・
・Fluorescent dye. Agent: Patent Attorney Ken Nori Chika Udo Norio Ogo (A)

Claims (3)

[Claims] (1) A fluorescent plate is constructed by arranging a group of optical fibers, each containing a fluorescent dye, in a single layer array, and at least one end face side of each of the optical fiber groups arranged in an array. A group of fluorescent-electrical conversion elements is disposed opposite to the fibers, and the image of the image primitive projected onto the fluorescent plate surface is time-sequentially converted into linear partial images intersecting with the optical fiber row. A line scanning means is provided which can divide the fluorescent light into parts and sequentially make the light incident on the surface of the fluorescent plate. An imaging device characterized by forming an electrical signal of a line image. (2) The imaging device according to claim 1, wherein the image of the image primitive is formed by visible or invisible light, and the scanning means is a liquid crystal optical shutter. (3) The imaging device according to claim 1, wherein each of the optical fibers has a rectangular cross section, and three side surfaces excluding the optical input surface are back reflective surfaces.