JPS6216667A - Image information reader - Google Patents

Abstract

PURPOSE:To make the titled reader small in size, and to improve the condensing efficiency by placing a photomultiplier tube having a photodetecting surface extended along a main scanning line as a photodetecting means, in the vicinity of a sheet, and also providing a reflecting optical element along the main scanning line. CONSTITUTION:An excitation light 1a which has been emitted from an excitation light source 1 is reflected and deflected by a galvanometer mirror 2, and executes a main scan in the direction as indicated with an arrow A on an accelerated phosphor sheet 3 which is carried in the direction as indicated with an arrow B by an endless belt device 9. A scanning position on the phosphor sheet 3 to which the excitation light 1a has been irradiated emits accelerated light in accordance with image information which has been accumulated therein, and this accelerated luminous light is detected by a long-sized photomultiplier tube 5. Also, a mirror 4 extended along a main scanning line is provided on the opposite side to the photomultiplier tube 5 against the main scanning line, and in the accelerated luminous light emitted from the scanning position of the sheet, light which has been emitted in other direction than the photodetecting surface of the photomultiplier tube 5 is reflected by the mirror 4 and made incident on the photomultiplier tube 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to an image information reading device for reading image information such as radiation image information, and in particular,
This invention relates to an improvement in the photodetection means of the above reading device.

(Technical Background and Prior Art of the Invention) Conventionally, a light beam such as a beam light is two-dimensionally scanned over a jet on which image information is recorded, and the sheet l-, -1=
Light containing image information (e.g., repulsed light, transmitted light, emitted light) obtained by irradiating the beam with light is detected by a light detection means equipped with a photomultiplier tube, etc., and is recorded on a sheet. 2. Description of the Related Art Image information reading devices that read image information are widely put into practical use.

Examples of such image information reading devices include plate-making scanners, combination coaters, and facsimile input devices, as well as radiation image information recording and reproducing devices using stimulable phosphor sheets, which have already been proposed by the applicant. System
No.-12429, No. 56-11395.

There is a radiation image information reading device used in Japanese Patent No. 56-11397, etc.).

In other words, when radiation (X-rays, alpha rays, beta rays, gamma rays, electron beams, ultraviolet rays, etc.) is applied to certain types of phosphors, some of this radiation energy is accumulated in the phosphors. It is known that when this phosphor is irradiated with excitation light such as visible light, the phosphor emits photostimulant light depending on the accumulated energy. called a fluorescent phosphor. The radiation image information reading device uses this stimulable phosphor to record radiation image information of a subject such as a human body on a sheet of stimulable phosphor, and uses this stimulable phosphor sheet i~. The device generates stimulated luminescence light by scanning with excitation light such as a laser beam, and reads the resulting stimulated luminescence light in a charging manner to obtain an image signal.

An example of the radiation image information reading device described above is shown in No. 9 below.
This is shown in the figure and explains the mechanism.

The excitation light 101a of ~ constant intensity emitted from the excitation light 11i 101 is incident on the galvanometer mirror 102, and the galvanometer mirror 102 directs the excitation light 101a to the galvanometer mirror 102 in the width direction of the stimulable phosphor sheet 103 placed below the galvanometer mirror 102. The laser beam is deflected and irradiated onto the stimulable phosphor sheet 103 so that the laser beam performs main scanning (scanning in the direction of the arrow). Stimulable phosphor sheet 103
For example, the stimulable phosphor sheet 103 is adsorbed by the stimulable phosphor sheet 109-L and transported in the direction of the arrow B, so that the main scanning is repeated by self-injection almost orthogonal to this sub-scanning, and the stimulable phosphor sheet 103 is covered over the entire surface. Two-dimensional scanning is performed using the excitation light 101a.

The part of the stimulable phosphor sheet irradiated with the excitation light 101a according to the scanning by the excitation light 101a emits stimulated light according to the image information stored there, and this emitted light is transmitted to the stimulable phosphor sheet. Light enters the light condenser 104 from the incident end surface 104a of a transparent light condenser 104, which has an incident end surface 104a formed parallel to the main scanning line in the vicinity.

This light condenser 1 (+4) has a front end 104b located near the stimulable phosphor sheet 103 formed into a flat shape and gradually becomes cylindrical toward the rear end. Since the end portion 104C has a substantially cylindrical shape and is coupled to a photomultiplier tube (photomultiply A7-) 105 provided on the exit end surface 104d, the stimulated luminescent light entering from the entrance end surface 104a is transmitted to the rear end. The photomultiplier 105 collects the stimulated luminescent light and transmits it to the photomultiplier 105 via a filter (not shown) that selectively transmits the stimulated luminescent light. After being converted into an electrical signal, the obtained electrical signal is sent to an image information reading circuit 106 for processing, and then outputted as a visible image to a CRT 107, recorded on a magnetic tape 108, or directly photographed. It may be recorded as a hard copy on materials, etc.

In the above-mentioned apparatus, the photodetection means for detecting stimulated luminescence light includes the photomultiplier 105 and the light condenser 10.
However, the condenser provided in the conventional device consists of an incident end surface 1 (14) located along the main scanning line.
As shown in the figure, it is large in order to transmit the stimulated luminescence light incident from A to the (4) multi-briar, which has a small width in the main scanning direction, by total reflection, and is equipped with such a condenser. There is a problem in that the entire reading device becomes larger.

Furthermore, as mentioned above, the stimulated luminescence light that is transmitted through total internal reflection within a large condenser may not be totally reflected at an angle and may be transmitted through the condenser. Large concentrators such as these also pose problems in terms of light collection efficiency. Furthermore, the light concentrator has a shape (in which a light-guiding sheet-like member such as an acrylic plate is formed such that one end corresponding to the incident end surface is linear and the other end corresponding to the exit end surface is aligned with the light receiving surface of the photomultiplier). For example, since it is made by deforming it into a cylindrical shape, it is difficult to process and the processing cost is high, and there is also the problem that the manufacturing cost for the amount of the product increases by −L.

(Object of the Invention) The present invention has been made in view of the problems mentioned above, and it detects light emitted from a sheet without using a large and complicated-shaped light condenser, thereby reducing the size of the sheet. It is an object of the present invention to provide an image information reading device that can improve light collection efficiency and reduce manufacturing costs.

(Structure of the Invention) The image information reading device of the present invention includes the above-described main scanning means, sub-scanning means, and light detection means for detecting light emitted from the sheet, wherein the light detection means includes: It is characterized by being equipped with a long photomultiplier tube having a light-receiving surface extending along the main scanning line and disposed close to the sheet, and further including a photomultiplier tube near the main scanning line. The present invention is characterized in that a reflective optical element is provided that extends along the scanning line and reflects light emitted from the sheet toward the light receiving surface.

In other words, in the reading device of the present invention, a long photomultiplier tube is prepared and placed close to the sheet as shown in 1-. Light emitted from the sea 1-, such as stimulated luminescence light, can be made to enter the light-receiving surface of the photomultiplier tube without using a light condenser. Furthermore, in the apparatus of the present invention, by providing the above-mentioned reflective optical element near the main scanning line, a part of the light emitted from the sheet can be reflected by the reflective optical element and made to enter the photomultiplier tube. Therefore, the efficiency of collecting light emitted from the sea 1 can be increased.

Note that a long photomultiplier tube is one whose light-receiving surface is provided along the main scanning line and is shaped so that the light emitted from the scanning position can be detected at any position in the main scanning direction. Tarru. It is particularly desirable that the length of the light-receiving surface of this long photomultiplier tube be equal to or longer than the reading scanning width on the sheet, but it may be slightly shorter than that. In particular, when a thin light condenser is arranged on the light receiving surface as described later, by devising the shape of the light condensing body, even if the length of the light receiving surface is somewhat shorter than the reading scanning width on the Efficient light detection is possible. Further, placing the photomultiplier tube close to the sheet means that the photomultiplier tube is placed close to the sheet so that the light emitted from the scanning position is directly and efficiently incident on the light receiving surface. This also means placing the photomultiplier tube at a distance from the sheet by the thickness of the filter and/or the light collector, so that it is possible to provide a filter or a light collector with a very small thickness on the light-receiving surface -F. It is something to do.

10- (Actual 77I! Embodiment) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an outline of a radiation image information reading device according to an embodiment of the present invention.

The excitation light 1a emitted from the excitation light a1 enters the galvanometer mirror 2, is reflected and deflected, and is sent to the endless belt which is the sub-scanning means! The stimulable phosphor sheet 3 conveyed in the direction of arrow B by the i-device 9 is main scanned in the direction of the arrow.

The scanning position on the stimulable phosphor sheet 3 irradiated with the excitation light 1a emits stimulated light according to the image information stored there. In the apparatus of the present invention, a long photomultiplier tube (photomultiplier) 5 is provided close to the stimulable phosphor sheet 3 as a photodetecting means for detecting the stimulated luminescence light emitted from this scanning position. is provided.

It is particularly preferable that the photomultiplier 5 has its light receiving surface 52 arranged along the main scanning line, so that stimulated luminescence emitted from any position in the main scanning direction can efficiently enter the interior from the light receiving surface 52. The length of the light receiving surface 52 is the sheet 3-
The reading scanning width of F is ten times larger. The stimulated luminescent light is converted into an electrical signal in this photomultiplier 5.
4, and the obtained electric signal is sent to an image information reading circuit (not shown) and processed, and then outputted as a visible image on a CRT or recorded on a magnetic tape.

Conventional photomultipliers are generally divided into several types, with electrodes in the multiplier part provided inside that multiplies a minute photocurrent to an appropriate level. A photomultiplier A7-sized can be made and covered by making these various types of photomultipliers M long in a direction perpendicular to their sides. The photomultiplier 5 used in the present invention shown in FIGS. 3A and 3B has an electrode structure that is generally called a box shape. A photocathode (which emits photoelectrons) is disposed within the main body 51, which has an empty interior, and which faces a long light-receiving surface 52 and emits photoelectrons.
A multiplier unit is provided with a photocathode (photocathode) 53, and below the photocathode 53, a plurality of (in this embodiment, 13) quarter-cylindrical M poles (dynodes) 54 to 66 having a secondary electron emission effect are combined. 67 are arranged. A shield electrode 68 is located opposite the lowermost dynode 66 of the multiplier 61.
An anode 69 is disposed within the shield electrode 68 for directing the N current to the east and taking it out as a signal.

Each of these electrodes is electrically connected on a one-to-one basis to each terminal of a terminal group 70 whose number corresponds to the number of electrodes provided on the opposite side of the light-receiving surface 52 (j).

Note that the dynodes 53 to 65 and the shield electrode [i
6 is identified and held within the main body 51 by a support member 71 made of an insulator.

FIG. 4 shows an electric circuit 80 for disrupting the photomultiplier 5 and extracting the photoelectric output, and the parts corresponding to each part of the photomultiplier 5 are given the same reference numerals as 1 and 1. . A corner high voltage is applied to the photocathode 53 via a negative high voltage application terminal 81. Further, the high voltage at the corner applied to the negative high voltage application terminal 81 is applied to the bleeder resistor group 82.
The voltages are divided and applied to the dynodes 53 to 65, respectively. Further, the shield electrode 68 is grounded,
Anode 69 is grounded via resistor 83 and connected to amplifier 8.
It is input to one terminal of 4. The other terminal of the amplifier 54 is grounded, and the photoelectrically converted image information is taken out as an electrical signal from an output terminal 85.

FIGS. 5A and 5B show another photomultiplier 15 used in the present invention, which has an electrode structure generally referred to as a Venetian blind type. This photomultiplier 15 has a main body 151 having a cylindrical shape, and a main body 151 facing a light receiving surface 152.
A photocathode 153 is provided along the photocathode 153, and below the photocathode 153, a plurality of plates (13 in this embodiment) of dynodes 154 to 166 are spread across an insulating member 172 and fixed with a bottle 113. It constitutes a multiplier 167. Each of the dynodes 154 to 166 is formed by making a large number of U-shaped cuts in a single conductive plate and bending the plate to form a blind shape. This multiplier 167
Below is a shield electrode 168 via an insulating member 172.
is fixed with a bottle 173, and positive = inside the shield electrode 168.
A 12-pole 169 is provided. These electrodes are electrically connected to a terminal group 170 provided at the side end of the main body 151, similar to the photomultiplier 5 shown in FIG.

Note that the extraction of the photoelectric output ( ) [, 1, J, is possible if the same circuit as shown in FIG. 4 is used. In addition, the elongated photomultiplier used in the present invention may include a multiplication section made of other types of conventionally known electrodes or a multiplication section formed by combining a plurality of types of electrodes. It can be created by extending the photo multiplier.

Further, in the apparatus of the present invention, a mirror 4 extending along the main scanning line is provided on the opposite side of the photomultiplier 5 with respect to the main scanning line, and as shown in FIG. Of the stimulated luminescent light emitted from the scanning position, N
The first photomultiplier is designed so that light emitted in a direction other than the incident end face 52 is reflected toward the light receiving surface 52. In the illustrated device, the mirror 4 is block-shaped, but if it extends along the main scanning line and can sufficiently reflect the stimulated luminescence light as described above, It may be in the shape of

Note that a reflective optical element such as a prism may be used instead of the mirror 13.

In this way, the reading device of this embodiment has a long photomultiply A7 with the light receiving surface arranged along the two fixed scanning lines.
- is placed close to the stimulable phosphor sheet, thereby eliminating the conventionally large and multi-axial shape.
! Since there is no need for an expensive condenser, 4i! i
It is possible to downsize the entire device and reduce manufacturing costs. In addition, the scanning position where the stimulated luminescent light is generated is close to the light receiving surface, and most of the stimulated luminescent light is directly applied to the light receiving surface.
Therefore, the light collection efficiency can be increased compared to the case where stimulated luminescence light is transmitted by a light collection body. Furthermore, by providing a reflecting mirror as described in ``2'' along the main scanning line and reflecting the stimulated luminescent light toward the light receiving surface, the focusing efficiency of the stimulated luminescent light can be improved. It is possible to increase one level.

By the way, among the image information reading devices, the radiation i!
In the Ii image information reading device, it is particularly necessary to efficiently collect stimulated luminescence light, which is light emitted from a stimulable phosphor sheet. Furthermore, when the excitation light is incident on the stimulable phosphor sheet, a part of it is reflected on the stimulable phosphor sheet, and a part of the reflected light is transmitted to the photomultiply 1.
It is necessary to ensure that the photomultiplier correctly detects only the stimulated luminescence light and does not detect the reflected light of the excitation light. Therefore, the long photomultiplier used in the radiation image information reading device has a very small light condenser on the same light receiving surface, and selectively collects only the light in the wavelength range of stimulated luminescence light. It is preferable to provide a filter that allows the light to pass through. FIG. 6 shows a specific example of a photomultiplier in which the light condenser and filter are provided on the light receiving surface.

FIG. 6(a) shows a photomultiplier 1 whose light-receiving surface is flat, for example, a filter 10 is provided on the light-receiving surface 52 of the box-shaped photomultiplier 5 shown in FIG.
Furthermore, an example is shown in which a plate-shaped condenser 11 made of acrylic resin or the like is provided on the filter 10. The light condenser 11 used in the device of the present invention has a relatively thin thickness and a simple shape as shown in the figure, so it reduces the size and manufacturing cost of the device like the conventional light condenser. There is no risk of it causing problems such as rising temperatures. Also"]
The positions of the filter 10 and the condenser 11 may be interchanged as shown in FIG. 6(b). Furthermore, Figure 6 (C)
As shown in FIG.
' is colored so as to selectively transmit only light in the wavelength range of stimulated luminescence light and absorb light in the wavelength range of excitation light, so that the condenser 11' also has the function of a filter. You can also do this. FIGS. 6(d>, (e) and (f) show the photomultiplier 1 having a curved light receiving surface, for example, the photomultiplier 15 of the Venetian blind type shown in FIG. 3 on the light receiving surface 152. Similarly, filter 1
0 and a light condenser 11 are shown. If the thickness of the filter 10' differs depending on the position as shown in FIG. ' It is sufficient to make the entire St distribution curved. Further, either one of the above-mentioned filter and light condenser may be provided on the light receiving surface of the photomultiply A1-.

Furthermore, if the length of the photomultiply A7- in the main scanning direction is somewhat shorter than the reading scanning width on the stimulable phosphor sheet 3, the condenser 11' is photomultiplyed as shown in FIG. The sheet 3 is configured to spread from the light-receiving surface 52 of the pliers 5 toward the stimulable phosphor sheet 3.
Stimulated luminescence light from the entire upper reading scanning width may be efficiently guided to the light receiving surface 52 of the photomultiply AC 5.

In addition, the mirror 4 mentioned above not only reflects the stimulated luminescence light, but also reflects the reflected light of the F excitation light toward the light-receiving surface of the photomultiplier. By using a mirror (for example, a dichroic mirror) that reflects only the light in the region and transmits or absorbs the light in the wavelength region of the excitation light, the influence of the reflected light of the excitation light can be further reduced.

By the way, in the device of the present invention, since the photomultiplier is made long, light may not enter the photomultiplier from a portion other than its light receiving surface.
When a filter is provided, if light that does not pass through the filter is incident, this light becomes noise in the reproduced image, which is undesirable. Therefore, as shown in FIG. 8, if the photomultiplier 17-15 is covered with a light-shielding case 12, the above-mentioned light will be prevented from entering the photomultiplier, and more accurate image information will be obtained. can be read. The illustrated photomultiplier is, for example, provided with a light condenser 11 on the light receiving surface 152 and a filter 10 on the incident end surface 11a of the light condenser. The surface other than the light-receiving surface and the surface of the condenser 11 that is not in contact with the filter 10 may be covered with a light shielding case.

In addition, the photomultiplier is easily affected by external magnetic fields, and when affected by the magnetic field, the photocurrent multiplication factor is significantly reduced. Since the photomultiplier of the present invention is long, it is considered that it is more susceptible to the influence of magnetic fields than conventional photomultipliers due to its structure and the design of the entire device.

Therefore, it is more preferable that the light-shielding case 12 is made of permalloy or the like and also has the function of a magnetic shielding case.

The apparatus of the present invention has been explained above by taking a radiation image information reading apparatus using a stimulable phosphor sheet as an example, but the apparatus of the present invention can also be applied to image information reading apparatuses other than the above-mentioned radiation image information reading apparatus. It goes without saying that effects similar to those described above can be achieved with any device.

(Effects of the Invention) As explained above, according to the image information reading device of the present invention, by providing the elongated photo multiplier close to the sheet, the light condensing device can be The light emitted from the sheet can be detected without using the body. Therefore, it is possible to downsize the entire device and reduce manufacturing costs, and it is also possible to increase the efficiency of condensing light emitted from the sheet. Also, along the main scanning line, the light emitted from the sheet is applied to a photomultiplier.
By installing a mirror that reflects toward the light receiving surface of
- The efficiency of collecting the light can be further increased.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an overview of a radiation image information reading device according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing the function of a mirror in the device of the present invention, and FIG. A perspective view showing a long box-shaped photomultiplier used in the device, FIG. 3(B) is a sectional view taken along line I-I, and FIG. 4 is a drive circuit for the photomultiplier shown in FIG. 3. Figure 5 (A) is a perspective view showing a long Venetian blind type photomultiplier used in the device of the present invention, Figure 5 (B) is a sectional view taken along the line I--I, and Figure 6 7 is a schematic diagram showing a photomultiplier A7- equipped with a filter and a condenser to improve light reception, FIG. 8 is a perspective view showing a photomultiplier housed in a light-shielding case, and FIG. 9 1 is a perspective view showing an outline of a conventional radiation image information reading device. 1a...Excitation light 3...Stimulable phosphor sheet 4...Mirror-5.15...Photoelectron multiplication Tube (photomultiplier) 52, 152... Light receiving surface 10... Filter 11... Light concentrator

Claims (1)

[Scope of Claims] 1) Main scanning means for main-scanning a sheet on which image information is recorded with a light beam and generating light containing the image information from the sheet; In an image information reading device, the image information reading device includes a sub-scanning unit that performs sub-scanning by moving in a direction substantially perpendicular to the main-scanning direction, and a photo-detecting unit that detects light emitted from the sheet. an elongated photomultiplier tube having a light-receiving surface extending along a line and disposed close to the sheet; An image information reading device comprising a reflective optical element that reflects light emitted from the sheet toward the light receiving surface. 2) The sheet is a stimulable phosphor sheet on which radiation image information is accumulated and recorded, and the light beam emits stimulable luminescent light according to the image information accumulated and recorded on the stimulable phosphor sheet. 2. The image information reading device according to claim 1, wherein the photodetecting means detects the stimulated luminescent light. 3) The photodetecting means is arranged such that the light is incident on the light-receiving surface of the photomultiplier tube, facing the filter and/or the photostimulable phosphor sheet that selectively transmits light in the wavelength range of the stimulated luminescent light. 3. The image information reading device according to claim 2, further comprising a light condenser that allows the stimulated luminescence light to enter from an end face and guides it to the light receiving surface.