JPS63175571A - Photodetector - Google Patents

Abstract

PURPOSE:To eliminate the effect of atmospheric humidity and to prevent the deterioration in adhesive by using a humidity proof agent so as to coat side faces of the adhesive adhering an optical element to a optical detecting face of a photoelectric multiplier. CONSTITUTION:A long photoelectric multiplier 5 arranged near a scanned face and having an optical detecting face 5a prolonged along the scanning line of a light beam 10 in a picture information reader, and an optical detecting element adhered onto the optical detecting face 5a of the photoelectric multiplier 5 adhered by an adhesives 7 having a light transmittivity are provided and the side face of the adhesives 7 is coated by a humidity proof material 8. Thus, adhering the optical element such as a filter 6 and an optical guide 4 to the optical detecting face 5a of the long photoelectric multiplier 5, the deterioration in the adhesives 7 due to humidity is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a photodetection device used in an image information reading device that reads image information such as radiation image information. It is related to.

(Prior art) Conventionally, a light beam such as a laser beam is scanned two-dimensionally on a sheet on which image information is recorded, and the sheet contains image information obtained by irradiating the light beam onto the sheet. Light (e.g. reflected light, transmitted light.

Image information reading devices that detect image information recorded on a sheet by detecting emitted light (emitted light) are in widespread 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
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 a certain type of phosphor is irradiated with radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.), a portion of this radiation energy is accumulated in the phosphor, causing the phosphor to It is known that when irradiated with excitation light such as visible light, phosphors exhibit stimulated luminescence depending on the accumulated energy.
A phosphor exhibiting such properties is called a stimulable 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 stimulable phosphor sheet, and then uses this stimulable phosphor sheet with a laser beam. The device scans with excitation light such as light to generate stimulated luminescent light, and photoelectrically reads the resulting stimulated luminescent light to obtain an image signal.

These image information reading devices incorporate a photodetection device equipped with a photomultiplier or the like that photoelectrically detects light containing image information such as stimulated luminescence light. Hereinafter, a radiation image information reading device equipped with a conventional photodetector will be explained with reference to FIG.

~ Constant intensity excitation light 101 emitted from excitation light source 101
a is made incident on the galvanometer mirror 102, and the galvanometer mirror 102 sends excitation light in the width direction of the stimulable phosphor sheet 103 placed below the galvanometer mirror 102 in main scanning (scanning in six directions of arrows). ), the excitation light is deflected and irradiated onto the stimulable phosphor sheet 103. The stimulable phosphor sheet 103 is
For example, since the stimulable phosphor sheet 103 is attracted onto the endless belt device 109 and conveyed in the direction of arrow B, the main scan is repeated at an angle substantially perpendicular to this sub-scan, and the stimulable phosphor sheet 103
Two-dimensional scanning is performed by the excitation light 101a over the entire surface.

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. Enter parallel to the main scanning line in the vicinity Q'
J DVl: Transparent light guide with surface 104a formed therein
The light enters the light guide 104 from the incident end face 104a of i04.

The light guide 104 has a flat front end 104b located near the stimulable phosphor sheet 103, and a shape that gradually becomes cylindrical toward the rear end. Since it has a cylindrical shape and is coupled to a photomultiplier 105 provided on the exit end surface 104d, the stimulated luminescent light entering from the incident end surface 104a is guided to the rear end 104c, and the stimulated luminescent light is The signal is transmitted to the photomultiplier 105 via a filter (not shown) that selectively transmits the signal. In the photomultiplier 7-105, the stimulated luminescent light is converted into an electrical signal, and the obtained electrical signal is sent to the image information reading circuit 10G.
After being sent to and processed by, for example, outputted as a visible image on a CRT 107, recorded on a magnetic tape 108, or directly recorded as a hard copy on a photographic material or the like.

(Problems to be Solved by the Invention) In the above-mentioned device, the photodetecting device consisting of the light guide 104 and the photomultiplier 105 is incorporated to detect stimulated luminescence light. However, the light guide 104 used in the conventional photodetecting device has a width in the main scanning direction by total reflection of the stimulated luminescence light input from the entrance end surface 104a provided along the main scanning line. In order to convey the information to the small multipliers, the J shown in the figure is made larger, and the light detection device equipped with such a light guide, and furthermore, the entire reading device becomes large. There is a problem. In addition, as mentioned above, the stimulated luminescence light that is transmitted through the large light guide by total internal reflection may pass through the light guide without being totally reflected at an angle, so that Such large light guides also have problems with light transmission efficiency. Furthermore, the above-mentioned light guide is made by deforming a light-guiding sheet 1-shaped member such as an acrylic plate into a shape (e.g., cylindrical) that matches the exit end surface, with one end corresponding to the entrance end surface being linear. For,
There is also the problem that the processing is difficult and the processing cost is high, and the manufacturing cost of the photodetecting device increases.

Therefore, in view of the above problems, the present applicant has developed a method for detecting light emitted from a sheet without using a large and complicatedly shaped light guide using a long photomultiplier tube having a light receiving surface extending along the main scanning line. We have proposed a photodetecting device that can be miniaturized, improve light collection efficiency, and reduce manufacturing costs (Japanese Patent Application No. 156255/1984, etc.).

The present invention has been made in connection with a photodetector using the above-mentioned long photomultiplier tube, and optical elements such as filters and light guides are bonded to the light receiving surface of the long photomultiplier tube. An object of the present invention is to provide a photodetecting device that can prevent the adhesive from degrading due to humidity or the like.

<Means for Solving the Problems> The photodetection device of the present invention has a light receiving surface that extends along the scanning line of a light beam in an image information reading device, and is arranged close to a surface to be scanned. and an optical element bonded to the light-receiving surface of the photoelectron multiplier tube with a light-transmitting adhesive, and the side surface of the adhesive is coated with a moisture-proof material. It is something to do.

The elongated photoelectronic tube has a light-receiving surface arranged along the main scanning line, and has a shape that allows light emitted from a scanning position to be detected at any position in the main scanning direction. 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 surface to be scanned, but it may be slightly shorter than that. Particularly when placing a thin light guide on the light receiving surface as described later, by carefully designing the shape of the light guide, efficiency can be achieved even if the length of the light receiving surface is somewhat shorter than the reading scanning width on the surface to be scanned. Good light detection is possible. In addition, in this way, the photomultiplier tube can be
In this case, optical elements such as the above-mentioned light guide and a filter to be described later, for properly detecting light containing image information, must be directly bonded to the light-receiving surface of the photoelectron tube. Therefore, placing the photomultiplier tube close to the scanned surface means that the photomultiplier tube can be placed close to these optical elements so that these optical guides and filters, which have a very small thickness, can be installed on the light receiving surface. This means that it is placed away from the surface to be scanned by the thickness of , and as close to the scanning line as possible.

(Function) 81 The photodetection device of the present invention is equipped with a long photomultiplier tube disposed close to the scanned surface as described above, thereby eliminating the need for large and complicated conventional devices. Light emitted from a sheet of stimulated luminescence light can be made incident on the light-receiving surface of a photomultiplier tube without using a shaped light guide, making it possible to miniaturize the device and improve photodetection efficiency. . Furthermore, necessary optical elements are bonded onto the light receiving surface of the elongated photomultiplier tube with a light-transmitting adhesive, but the adhesive is susceptible to deterioration due to the influence of moisture when exposed to the outside air. The above-mentioned long photomultiplier tube has a cylindrical shape as described below, and when a filter chrysanthemum with a flat bonding surface is attached to the curved light-receiving surface, a layer of adhesive is applied at the side end. As the thickness increases, the above deterioration is more likely to occur. When the adhesive deteriorates, its adhesive action weakens, and its light transmittance also changes, making it impossible to perform accurate readings. However, in this device, the sides of the adhesive are covered with a moisture-proof material. This avoids the inconvenience of adhesive deterioration.

(Example) Hereinafter, an example 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 equipped with a photodetection device according to an embodiment of the present invention.

Excitation light 1a emitted from excitation light source 1 enters galvanometer mirror 2, is reflected and deflected, and travels on stimulable phosphor sheet 3, which is conveyed in the direction of arrow B by endless belt device 9, which is a sub-scanning means, in the direction of arrow B. Main scan in the direction. 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. As a means for detecting the stimulated luminescence light emitted from this scanning position, in this apparatus, a long photomultiplier tube (photomultiplier) is installed in the vicinity of the photostimulable phosphor sheet 3.
) 5 is provided.

It is particularly preferable that the photomultiplier 5 has its light-receiving surface 5a 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 5a. The length of the light-receiving surface 5a is longer than the reading scanning width on the sheet 3.

Conventional photomultipliers are generally divided into several types depending on the structure of the electrodes in the multiplier part provided inside that multiplies a minute photocurrent to an appropriate level, but the long photomultiplier of the present invention - can be created by extending these various photomultipliers in a direction perpendicular to their sides. Figure 2(a),
The photomultiplier 5 used in this embodiment shown in FIG. 2(b), which is a sectional view taken along the line I-I, has an electrode structure generally referred to as a Venetian blind type. . This photo multiplier
5, the main body 5A has a cylindrical shape, and the light receiving surface 5a
A photocathode 5b is provided along the main body 5A opposite to the photocathode 5b, and a plurality of photocathode (13 in this embodiment) are provided below the photocathode 5b.
dynodes 5C are stacked on top of each other with an insulating member 5d interposed therebetween and fixed with a bottle 5G to form a multiplier 5f. Each of the dynodes 5C is formed by making a large number of U-shaped cuts in one conductive plate and bending the plate to form a blind shape. A shield electrode 5g is fixed below this multiplier 5f via an insulating member 5d with a bottle 5e,
An anode 5h is provided within the shield electrode 5g.
It is electrically connected to each terminal of 1 in a one-to-one correspondence.

FIG. 3 shows an electric circuit 12 for driving the photomultiplier 5 and extracting a photoelectric output, and parts corresponding to each part of the photomultiplier 5 are given the same reference numerals. A negative high voltage is applied to the photocathode 5b via a negative high voltage application terminal 12a. Further, the negative high voltage applied to the negative high voltage application terminal 12a is applied to the bleeder resistor group 12.
The voltages are divided by b and applied to the dynodes 5C, respectively. Further, the shield electrode 5g is grounded, and R;
The J pole 5h is grounded via a resistor 12c and is also input to one terminal of an amplifier 12d. The other terminal of the amplifier 12d is grounded, and the photoelectrically converted image information is taken out as an electrical signal from the output terminal 12e. Note that the shield electrode 5g does not necessarily need to be provided.

By the way, among various image reading devices, in the above-mentioned radiation image information reading device, it is especially important to efficiently guide the stimulated luminescent light, which is the light emitted from the stimulable phosphor sheet, to the light receiving surface of the photomultiplier. Needed. Furthermore, when the excitation light is incident on the stimulable phosphor sheet, a portion of the excitation light may be reflected on the stimulable phosphor sheet, and a portion of the reflected light may reach the light receiving surface of the photomultiplier. can be,
The photomultiplier needs to correctly detect only the stimulated luminescence light and not detect the reflected light of the excitation light. Therefore, a long filter 6 and a small light guide 4 are joined to the light receiving surface 5a-11 of the long photomultiplier 5 in the apparatus of this embodiment. , and the light guide 4 constitute a photodetecting device 10. A front view of this photodetector 10 is shown in FIG.

On the light-receiving surface 5a of the photomultiplier 5, a filter 6 is bonded via an ultraviolet curing adhesive 7, which is an example of a light transmitting agent. A light guide 4 is integrally arranged. The filter 6 selectively transmits only light in the wavelength region of stimulated luminescence light, thereby cutting off the light reflected from the excitation light sheet 3, and is a cylindrical light-receiving surface of the photomultiplier 5. The joint surface with respect to 5a is a flat surface. Therefore, the adhesive 7 for bonding the filter 6 onto the light-receiving surface 5a has a relatively large thickness at both ends thereof. On the other hand, the light guide 4 transmits the stimulated luminescence light emitted from the scanning position to the photomultiplier 5 by total reflection, and the light guide used in this photodetection device receives the light as shown in the figure. Since the length from the surface to the light exit surface is very short (and the shape is simple), there is no risk of causing problems such as an increase in the size of the device or an increase in manufacturing costs, unlike in conventional light guides.

As mentioned above, the adhesive 7 has a large thickness on the side surface that comes into contact with the outside air, and is easily affected by the humidity of the outside air.
In this device, a moisture-proof material 8 is applied to the adhesive 7, the side surfaces of the filter 8, and the lower end of the photomultiplier 5. If the moisture-proof material 8 is applied in this manner, there will be no problem that the adhesive will deteriorate due to the influence of the humidity of the outside air. As this moisture-proof material, for example, epoxy paint, silicone material, etc. are suitably used.

Further, instead of applying a moisture-proof material, a film, tape, or the like made of a moisture-proof material may be attached to at least the side surface of the adhesive 7. Furthermore, since the filter 6 and the light guide 4 are also bonded together with an adhesive, a moisture-proof material may also be applied around this bonding surface.

In a reading device equipped with such a light detection means 10, the stimulated luminescence light emitted from the scanning position is transmitted through the light guide 4.
and is transmitted to the photomultiplier 5 via the filter 6.

The photomultiplier 5 converts the stimulated luminescent light into an electrical signal, and the obtained electrical signal is sent to an image information reading circuit (not shown) for processing (e. recorded on magnetic tape.

As described above, the photodetection means according to this embodiment has a long photomultiplier whose light-receiving surface is aligned with the main scanning line, and is arranged close to the stimulable phosphor sheet.
The conventionally used light guide, which has a large and complicated shape and is expensive to manufacture, is no longer required, making it possible to downsize the entire device and reduce manufacturing costs. Can be made compact. Furthermore, since the scanning position where the stimulated luminescence light is generated is close to the light receiving surface, the light transmission efficiency can be increased compared to the case where the stimulated luminescence light is transmitted by a conventional light guide. moreover,
By coating the sides of the adhesive that joins the light-receiving surface of the photomultiplier and the filter with a moisture-proof material, it is possible to reduce the thickness of the adhesive, especially when the surface of the adhesive that comes into contact with the outside air becomes thicker depending on the shape of the photomultiplier. However, the adhesive will not deteriorate due to humidity. In addition, -1
6~ Long photomultipliers are not limited to the Venetian blind type mentioned above, but can also be multipliers made of other types of conventionally known electrodes, or multipliers made of a combination of multiple types of electrodes. It is possible to create it by extending photomultipliers equipped with. For example, it may be a long photomultiplier formed by extending a photomultiplier having a so-called box-type electrode structure. In the case of a box-type photomultiplier, the light-receiving surface is generally flat, and when bonding it to a filter, etc., there may be a problem that the adhesive may become thick in some areas, but the adhesive Applying a moisture-proof material to the side of the adhesive will further ensure the adhesive effect.

Further, the optical element bonded to the light receiving surface of the photomultiplier is not limited to the above-mentioned filter. Another embodiment of the photodetecting device of the present invention will be described below with reference to FIG.

Figure 5(a) shows the light receiving surface 5 of the photomultiplier 5.
This shows an example in which the light guide 4 is joined to the light guide 4 on the light guide 4 and the above-described filter 6 is joined to the incident end surface of the light guide 4, and the positions of the light guide and the filter are replaced with those of the above-mentioned embodiment. In this case as well, since the end face of the adhesive 7 becomes thick, it is preferable to apply the moisture-proof material 8 as shown in the figure to prevent deterioration of the moisture-proof agent. In addition, as shown in FIG. 5(b), the light guide 11 provided on the light receiving surface 5a,
The light guide 11 may also have the function of a filter by being 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. Furthermore, when the photodetection device is placed in a reading device that detects reflected light from a scanned surface, other than a radiation image information reading device using the stimulable phosphor sheets 1 to 1, the above-mentioned filter is Since this is not necessary, only the light guide 4 may be bonded onto the light receiving surface 5a of the photomultiplier R-5 as shown in FIG. 5(C).

Furthermore, if the length of the photomultiplier in the main scanning direction is somewhat shorter than the reading scanning width on the surface to be scanned, the light guide 4 is moved to the light receiving surface 5a of the photomultiplier 5 as shown in FIG. The structure is configured so that the light spreads from the scanning surface 3' toward the scanned surface 3', and the light containing image information from the entire scanning width on the scanned surface 3' is efficiently photomultiplied A.
7-5, which can guide the light to the light receiving surface 5a.

(Effects of the Invention) As described above in detail, the photodetection device of the present invention includes a long photomultiplier disposed close to the scanned surface along the scanning line. J: The surface to be scanned can be scanned without using the conventional large and uniquely shaped light guide.
The emitted light can be detected. Therefore, it is possible to reduce the overall size and manufacturing cost of the photodetection device and the reading device in which the photodetection device is incorporated, and it is also possible to increase the detection efficiency of light emitted from the scanned surface. By coating the side surface of the adhesive that joins the optical element to the light-receiving surface of the photomultibrier with a moisture-proofing agent, it is possible to eliminate the influence of the humidity of the outside air and prevent the adhesive from deteriorating.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an outline of a radiation image information reading device 3A equipped with a photodetection device according to an embodiment of the present invention, and FIG.
A perspective view showing a blind type photomultiplier, FIG. 2(b) is a sectional view taken along the line I-I, FIG. A front view of the above-mentioned photodetection device, FIGS. 5(a) to (C) are perspective views of a photodetection device according to another embodiment of the present invention, and FIG. 6 is a side view of a photodetection device according to yet another embodiment. , FIG. 7 is a perspective view showing an outline of a radiation image information reading device equipped with a conventional photodetection device. 1a...Excitation light 3...Stimulable phosphor sheet 4...Light guide 5...Photoelectron intensifier tube (20A) 2O
- 5a... Light receiving surface 6... Fi
Tough...Adhesive 8...Moisture-proofing material Size 10...Photodetection device 4/9 1/91 Le l (c) Figure 6 Figure 7 Figure 1 Incident display 1988 Patent Application No. 007.334 2, Name of the invention Photodetection device 3, Relationship to the case of the person making the amendment Patent applicant Location 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Name (
520) Fuji Photo Film Co., Ltd. Representative Name Nishi
Fact 4. Address of the agent: 5-2-1 Roppongi, Minato-ku, Tokyo, Uraiya Building 7F446, Drawing 7 subject to amendment, Contents of amendment Figure 7 will be amended as attached.

Claims (1)

[Scope of Claims] 1) A photodetector for detecting light containing image information emitted from a scanned surface when a light beam scans the scanned surface on which image information is recorded, wherein the light an elongated photomultiplier tube having a light-receiving surface extending along the scanning line of the beam and disposed close to the surface to be scanned; and a light-transmitting adhesive on the light-receiving surface of the photomultiplier tube. 1. A photodetection device comprising an optical element bonded with an adhesive, and a side surface of the adhesive is coated with a moisture-proof material. 2) The surface to be scanned is a stimulable phosphor sheet on which radiation image information is accumulated and recorded, and the light beam emits photostimulable light according to the image information accumulated and recorded on the stimulable phosphor sheet. The photodetecting device according to claim 1, characterized in that the excitation light is excitation light that generates light. 3) Claim 2, wherein the optical element is a filter that selectively transmits the stimulated luminescence light.
The photodetection device described in Section 1.