JPS6294066A - Image information reader - Google Patents

Abstract

PURPOSE:To scale down a photodetecting means by arranging a photodetector composed of a long-sized photoelectric transfer body and a long-sized microchannel as a photodetecting means close to a sheet. CONSTITUTION:The sheet 13 is mainly scanned in the direction of an arrow A by a light beam 11a. On the other hand, a stimulable luminescent sheet 13 is conveyed in the direction of an arrow B by an endless belt device 19, and sub-scanned in the vertical direction. The photodetector composed of the long- sized photoelectric transfer body 14 and the microchannel plate 15 is provided close to the stimulable luminescent sheet 13. The long-sized photoelectric transfer body 14 is disposed along the main scan line so that its light receiving surface 14a can be opposite to the lower stimulable luminescent sheet 13. Thus stimulable luminescent beams emitted from any main scan positions can efficiently make incident from the light receiving surface 14a without moving the photoelectric transfer body 14 and the sheet.

Description

Detailed Description of the Invention [Field of the Invention] The present invention relates to an image information reading device that reads image information such as radiographic image information, and more specifically, to an improvement in light detection means of the image information reading device. It is related to.

[Technical Background of the Invention and Prior Art] Conventionally, a sheet on which image information is recorded is two-dimensionally scanned with a light beam such as a laser beam, and device information composed of the sheet is acquired by irradiation with the light beam. A device (image information reading device) that reads image information recorded on a sheet by detecting the light (e.g. reflected light, transmitted light, emitted light) with a photodetector equipped with a photomultiplier tube, etc. is widely used. It is put into practical use.

Such image information reading devices include plate-making scanners, computer and facsimile input devices, etc.
A radiation image information recording and reproducing system using a stimulable phosphor sheet already proposed by the applicant (Japanese Patent Laid-Open No. 5
5-. No. 12429, No. 56-11395, No. 56-
There is a radiation image information reading device used in Japanese Patent No. 11397, etc.).

When certain types of phosphors are irradiated with radiation (X-rays, alpha-rays, beta-rays, gamma-rays, electron beams, ultraviolet light, etc.), some of this radiation energy is stored in the phosphor, and then this phosphor becomes visible. It is known that when irradiated with electromagnetic waves (excitation light) such as light, phosphors emit fluorescence (stimulated luminescence light) depending on the accumulated energy, and phosphors that exhibit this property are known as stimulable light. It is called a phosphor. The above-mentioned radiation image information recording and reproducing system 1 utilizes this stimulable phosphor, and the radiation image information of a subject such as a human body is once recorded as an image of accumulated radiation energy on a sheet made of stimulable phosphor. After that, this photostimulable phosphor sheet is scanned with excitation light such as l/-za light to generate stimulated luminescence light, and then this stimulated luminescence light is read photoelectrically to obtain an electrical signal. It is something.

The structure of a radiation image information reading device used in a radiation image information recording and reproducing system will be explained below with reference to the example shown in FIG.

FIG. 1 is a perspective view showing an example of a conventional radiation image information reading device equipped with a photodetector A consisting of a light condenser and a photon-r multiplier tube as a photodetection means.

In FIG. 1, a light beam (excitation light) la of a constant intensity generated from an excitation light source 1 is deflected by a galvanometer mirror 2 and is directed onto a stimulable phosphor sheet 3 placed below the galvanometer mirror 2. incident on the target. Due to this (Z"), the stimulable phosphor sheet 3 is scanned in the width direction (direction of arrow A) by the light beam 1a (main scan).

The stimulable phosphor sheet 3 is attracted to an endless belt device 9 and conveyed in the length direction (direction of arrow B) (sub-scanning). Therefore, the main scan is repeated at an angle substantially perpendicular to the sub-scan, and the entire surface of the stimulable phosphor sheet 3 is irradiated with the light beam 1a two-dimensionally.

The location of the stimulable phosphor sheet 3 that is irradiated with the light beam 1a by scanning the light beam 1a emits photostimulable light according to the radiation energy accumulated in that location, and the emitted light The light enters an incident end face 4a of a transparent light condenser 4 placed near the sheet 3. This light condenser 4 has a curved incident end surface 4a in the main scanning line, a front end 4b located near the stimulable phosphor sheet 3 is flat, and the front end 4b is flat, and gradually increases toward the rear end. It is formed into a cylindrical shape, and is connected to a photomultiplier 5 at the exit end surface of the substantially cylindrical rear end 4c. The stimulated luminescent light incident from the input end face 4a is collected at the rear end 4c, and then received by the photomultiplier 5 through a filter (not shown) that selectively transmits the stimulated luminescent light.

In the photomultiplier 5, the stimulated luminescent light is converted into an electrical signal, and this electrical signal is sent to an image information reading circuit 6 for signal processing, and then displayed on a display 7 such as a CRT.
- It can be outputted as a visible image, recorded on magnetic tape 8, or directly recorded as a hard copy on a photographic material or the like.

In the conventional device as described above, the photodetector for detecting stimulated luminescence light is composed of a light condenser and a photo-fultibrier, but this light condenser is The stimulated emitted light incident from the incident end surface with jQ L'j is totally reflected inside the emitted light, and the emitted light is guided to the exit end surface, and sent to a photomultiplier having a light receiving surface with a narrow width in the main scanning direction. Because of its functions, it is large-sized as shown in FIG. As a result, there is a problem in that the entire reading equipment equipped with such a light condenser becomes large in size.

In addition, the h2 light condenser is made of a light-guiding sheet-like member such as an acrylic plate, with one end corresponding to the incident end surface being made straight, and the other end corresponding to the exit end surface being the light-receiving surface of the photomultiplier. Deformation to the matching shape (e.g. cylindrical)
[Processing is difficult because it is manufactured by
There is also the problem that processing costs are high and the manufacturing cost of the entire installation increases.

Furthermore, when the stimulated emitted light is guided inside a large condenser by total reflection, a part of the emitted light may be transmitted through the condenser without being totally reflected angularly. Large condensing bodies such as those described above also have problems in light condensing efficiency.

[Summary of the Invention] The present invention has been made to eliminate or alleviate the problems as described in 1 above, and provides an image information reading device that is compact and capable of reducing manufacturing costs. Its purpose is to

Another object of the present invention is to provide an image information reading device equipped with 17 photodetection stages having high light collection efficiency.

That is, the image information reading Il! of the present invention! The core device extracts the image information from the sheet on which information about the image is recorded, = ii
-4'- Scanning the sheet 1- with an optical beam in order to emit light; 1- Scanning means, moving the sheet and the optical heater relatively in a direction substantially perpendicular to the -L scanning direction; In an image information reading device comprising a sub-scanning means and a light detection means for detecting light emitted from the sheet, the light detection means includes a light receiving surface extending along a scanning line; It consists of a long microchannel plate connected to the photoelectric converter, and is characterized in that 18 stages of photodetection are arranged close to the sheet.

The reading device of the present invention has eight lower stages of photodetection and one stage. By preparing a photodetector consisting of an elongated photoelectric converter and an elongated microchannel plate, and placing this photodetector close to the sheet, it is possible to avoid the large and complicated shape of the conventional one. The light emitted from the sheet, such as stimulated luminescence light, can be made incident on the light-receiving surface of the photoelectric converter without using a light condenser. Therefore, since the photodetecting means does not occupy a large capacity as in the conventional case, the entire reading device can be downsized. Furthermore, manufacturing costs can be reduced compared to a reading device equipped with a conventional combination of a light condenser and a photomultiplier tube.

In the present invention, a long photoelectric converter and a microchannel plate mean that when the light-receiving surface is arranged along the main scanning line of the light beam, the elongated photoelectric converter and the microchannel plate emit light from the scanning location of the sheet by -dimensional main scanning. One-dimensionally (
In other words, it means that it has a shape that can be detected at any position along the main scanning line. The length of the light-receiving surface of the elongated photoelectric converter and the microchannel plate is desirably equal to or longer than the reading scanning width of the sheet, but may be slightly shorter than that. For example, when placing a thin light condenser on the light-receiving surface, by devising the shape of the light-concentrator, it is possible to efficiently perform two light detections even if the length of the light-receiving surface is somewhat shorter than the reading scanning width of the sheet. is r】f-ability.

In addition, placing a photodetector consisting of a photosensitive sample and a microchannel plate in close proximity to the sheet means that the light emitted from the scanning location is directly and efficiently incident on the light-receiving surface of the photoelectric converter. In addition to fixing this photodetector near the sheet, it is also possible to install a filter or a very thin light collector on the light-receiving surface. and/or spaced apart from the sheet by the thickness of the light collector.

In particular, when a simple light collector is provided on the light receiving surface of the photoelectric converter as shown in ]-, the efficiency of collecting light emitted from the sheet can be improved.

[Structure of the Invention] An image information reading device of the present invention will be described with reference to the drawings.

FIG. 2 is a perspective view showing an example of an uninvented radiation image information reading device for reading a stimulable phosphor sheet on which radiation image information is stored and recorded.

In FIG. 2, a light beam l generated from an excitation light source 11
The light la is reflected and deflected by the galvanometer mirror 12 and is incident on the stimulable phosphor sheet 13 one-dimensionally. That is, the sheet 13 is main scanned in the direction of the arrow by the light beam lla.

On the other hand, the stimulable phosphor sheet 13 is mounted on an endless belt H
19 in the direction of arrow B. That is, the sheet 13 is sub-scanned in a direction perpendicular to the main scanning direction,
The entire surface of the sheet is irradiated with the light beam lla two-dimensionally.

A scanned location on the stimulable phosphor sheet 13 irradiated with the light beam lla emits stimulated luminescence light in an amount proportional to the radiation energy stored at that location. As a light detection means for detecting the stimulated luminescence light emitted from this scanning location,
In the apparatus of the present invention, a photodetector consisting of an elongated photoelectric converter 14 and a microchannel plate 15 is provided adjacent to the stimulable phosphor sheet 13.

A long light-centered specimen 14 is arranged along the main scanning line, and its light-receiving surface 14. a is placed so as to face the stimulable phosphor sheet 13 below. Thereby, stimulated luminescence light emitted from any position in the main scanning area can efficiently enter from the light receiving surface 14a without moving the photoelectric converter 14 and the sheet. Preferably, the light receiving surface 14. The length a is north of the reading scanning width of the sheet 13. This photoelectric converter 14 is made of, for example, 5b-Se,
Bi-0B1-0-A, pie alkali (K-C5-5b
etc.), multi-alkali (Na- to-Cs-Sb, etc.), C
It is made of s-Te and generates a number of electrons proportional to the intensity of stimulated luminescence light incident from the light receiving surface I4a.

A microchannel plate 15 is integrally joined to the side of the photoelectric converter 14 opposite to the light receiving surface 14a, and the electric current f generated in the photoelectric converter 14 immediately enters the microchannel plate 15. This micro channel play 415 is made up of a large number of hollow glass m with a diameter of about 10 m, the inside of which is evacuated, and the entrance of the fiber tube (the side connected to the photoelectric converter 14). When a voltage (for example, about IKV) is applied between the fiber tube and the outlet (the side connected to the image information reading circuit 16), the inner wall surface of each fiber tube forms a secondary electronic surface. Therefore, the electrons incident on the microchannel plate 15 are multiplied by secondary electrons while repeatedly colliding with the inner wall surface of the fiber tube. Generally, the microchannel plate provides an electron multiplication factor of about 10' to 10' with low noise.

The multiplied electrons are sent to the image information reading circuit 16 and subjected to signal processing, and then outputted as a visible image to a CRT or the like (not shown) or recorded and stored on a magnetic tape or the like.

Among the image information reading devices, in the above-mentioned radiation image information reading device, it is desirable to be able to efficiently collect the stimulated luminescence light emitted from the stimulable phosphor sheet. Furthermore, a part of the excitation light for causing the stimulable phosphor sheet to stimulate luminescence is reflected on the sheet surface, and a part of the reflected light may reach the light receiving surface of the photoelectric converter. The device must be configured to detect only the stimulated luminescence light and not the reflected excitation light.

Therefore, in order to increase the light collection efficiency of the L light distribution detector, it is preferable to provide a light condenser with a very small thickness on the light receiving surface of the photoelectrically variable specimen in accordance with the shape of the light receiving surface. In addition, in order to remove the reflected excitation light, it is preferable to provide a filter on the light receiving surface that selectively transmits only light in the wavelength region of stimulated luminescence. FIG. 3 shows a specific example of a photodetector made of the following.

In FIG. 3(a), a light receiving surface 14a of a photodetector consisting of a photoelectric converter 14 and a microchannel plate 15 is shown.
A filter 17 is provided on the top, and this filter 1
A plate-shaped light collector 18 made of acrylic or the like is provided on the seventh hill.

Further, as shown in FIG. 3(b), the attachment positions of the filter 17 and the light condenser 18 may be interchanged with each other.

In FIG. 3(e), the light receiving surface 14 a J of the photodetector
: includes a light condenser 1 colored so as to selectively transmit light in the stimulated emission wavelength range and absorb light in the excitation light wavelength range;
8° may be provided.

This blue light condenser has both the original function as a light condenser and a filter function.

The light condenser 18 used in the device of the present invention is extremely thin and has a simple shape as shown in FIG. Even so, it is possible to solve the problems of increasing the size of the photodetector (and thus the device) and increasing the manufacturing cost, which were problems when using the conventional light condensing body.

In addition, if the length of the photodetector is shorter than the reading scanning width of the stimulable phosphor sheet, the light condenser 18 as shown in FIG.
'' has a shape that gradually spreads from the light-receiving surface 14a of the photoelectric converter 1.4 toward the photostimulable phosphor sheet 13 below, so that the luminescence J2 ( Efficiently converts emitted light into light 1 and converts it into converter 1
4 can be received and guided to n114a.

Furthermore, in order to increase the light collection efficiency of the photodetector, the photodetector has a light-receiving surface 1 for the light-modified specimen 14, as shown in FIG.
An integrating cylinder 20 having an inner surface facing the inner surface thereof may be provided extending in the main scanning direction. This integrating tube is made of a cylindrical member having optical characteristics similar to that of an integrating sphere used as a part of a spherical photometer. A slit is provided to allow the sheet to pass through, and the lower end has an opening at a position corresponding to the main scanning position of the sheet.

The inner surface of this integrating tube is coated with a white paint with high diffuse reflectance, and among the stimulated luminescence light emitted from the scanned portion of the sheet, the light that does not directly enter the light-receiving surface 14a is absorbed by the inner surface of the integrating tube. After repeated diffuse reflections, the light is incident on the light-receiving surface 14a.

In addition, by coloring the inner surface of this integrating cylinder so as to reflect light in the stimulated emission wavelength range and absorb light in the excitation light wavelength range, the influence of reflection of excitation light can be further reduced. .

The apparatus of the present invention has been described above, taking as an example a radiation image information reading apparatus for a stimulable phosphor sheet. However, the apparatus of the present invention is not limited to an L-ray image information reading apparatus; The present invention applies to any image information reading device as long as it is an image information reading device for reading a sheet on which information is recorded and the image information can be emitted as light (reflected light, transmitted light, emitted light, etc.) include.

Of course, any such device can achieve the above-mentioned miniaturization and manufacturing cost reduction.

According to the image information reading device of the present invention, by providing a photodetector consisting of a long photoelectric converter and a microchannel plate in close proximity to a sheet on which image information is recorded, It is possible to easily detect the light emitted from the sheet without using a light condenser with a specific shape. This makes it possible to downsize the entire device and reduce manufacturing costs.

Furthermore, by using a combination of a long photoelectric converter and a microchannel plate as the light detection means, it is possible to increase the efficiency of collecting light emitted from the sheet. In particular, by providing a simple light condenser on the light-receiving surface of the photoelectric converter, or by providing an integrating tube that can diffusely reflect light.

-・Layer light collection efficiency can be increased.

[Brief explanation of drawings]

FIG. 1 is a perspective view schematically showing an example of a conventional radiation image information reading device. FIG. 2 is a perspective view schematically showing a radiation image information reading device which is an example of the image information reading device of the present invention. FIG. 3 is a perspective view showing an example of a photodetector in which a filter and a condenser are provided on the light receiving surface. FIG. 4 is a side view showing another example of a photodetector in which a filter and a condenser are provided on the light receiving surface. FIG. 5 is a perspective view showing an example of a photodetector including a filter and a condenser on the light receiving surface and an integrating tube. 11: Excitation light source, lla: Light beam, 13: Stimulable phosphor sheet, 14: Photoelectric converter, 14a: Light receiving surface, 15: Microchannel plate, 16: Image information reading circuit, 17: Filter, 18: Collection light body

Claims (1)

[Claims] 1. a main scanning means for scanning a light beam over a sheet on which image information is recorded in order to emit light having image information from the sheet; and relative to the sheet and the light beam in a direction substantially perpendicular to the main scanning direction. In an image information reading device comprising a sub-scanning means for moving the sheet and a light detection means for detecting light emitted from the sheet, the light detection means has a photoelectric conversion surface having a light receiving surface extending along a main scanning line. 1. An image information reading device comprising a long microchannel plate connected to the photoelectric conversion body and the photoelectric conversion body, and the photodetection means is disposed close to the sheet. 2. The sheet is a stimulable phosphor sheet on which radiation image information is stored and recorded, and the light beam is an excitation light for producing stimulated luminescent light having radiation image information from the stimulable phosphor sheet. 2. The image information reading device according to claim 1, wherein the photodetecting means detects the stimulated luminescence light. 3. The photodetecting means includes a filter that selectively transmits light in the stimulated emission wavelength region on the light receiving surface of the photoelectric converter, and/or a filter that selectively transmits the stimulated emission light from an incident end surface facing the photostimulable phosphor sheet. 3. The image information reading device according to claim 2, further comprising a light condenser that directs the incident light to the light receiving surface of the photoelectric converter.