Abstract:
In an image information reader  100  that includes an excitation light source  45 , a photoelectric reading mechanism, and an external light shield for reading a sample distributing specific organism-originated material labeled with a fluorescent dye, a sample tray  10  is provided having the qualities of easy rinsing and enduring of repeated use. The sample tray includes a base material, e.g. an aluminum plate  10   d , that is coated with a fluororesin, e.g. an hybrid resin  10   c  of PTFE and PFA having a black color as a base. The tray can also include depressed or projected markings  10   a  on the surface on which the sample is placed which represent a readable range of the photoelectric reading mechanism. A method of making the sample tray for the reader is also described.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sample tray to be used in an image information reader for reading the fluorescent image of a fluorescence-labeled sample and a fabrication method thereof. 
     2. Description of the Related Art 
     In the field of biological chemistry and molecular biology, a fluorescence detecting system using a fluorescent dye as a labeling material is hitherto known. According to this system, the evaluations of the arrangement of a gene, the expression level of a gene, the path and state of the metabolism, absorption, and excretion of an applied material in a laboratory mouse, the separation, identification, molecular weight, and characteristics of protein, etc. can be performed, by reading out information about the image of a sample distributing specific organism-originated materials labeled with a fluorescent dye. 
     For example, using the electrophoresis that causes a living cell in suspension or a biological compound (protein, etc.) in a solution to move to a positive or negative electrode through an electric field by the electric charge, a plurality of DNA fragments are electrophoresed on a gel support body, after a fluorescent dye has been added into a solution containing the plurality of DNA fragments. Alternatively, a plurality of DNA fragments are electrophoresed on a gel support body containing a fluorescent dye, or, after a plurality of DNA fragments have been electrophoresed on a gel support body, this gel support body is immersed into a solution containing a fluorescent dye. In this way, a gel support body (sample) distributing specific DNA fragments (organism-originated materials) labeled with fluorescence is obtained. With external light shielded, the obtained gel support body is irradiated with excitation light for exciting the fluorescent dye employed as a labeling material. The fluorescence emitted from the gel support body is photoelectrically read out. In this way, image information representing a distribution of DNA fragments labeled with fluorescence is acquired, and based on the acquired image information, a visual image is displayed on a display section such as a CRT display, whereby the evaluation of the molecular weight of the DNA fragment and the like can be performed. 
     Incidentally, in an image information reader to be used in the aforementioned fluorescence detecting system, a sample such as a gel support body is placed on a sample tray. This sample tray usually employs an aluminum sample tray processed with a black Alumite (or Alumilite) so that fluorescence is not erroneously detected. 
     However, once a fluorescent dye and the like adhere to the aforementioned sample tray, it will take substantial labor to rinse out the fluorescent dye completely. When it cannot be removed to the degree that does not have a bad influence upon fluorescence detection, fluorescence is erroneously detected and therefore the greatest attention must be paid in handling it and sometimes the sample tray cannot be reused. 
     Hence, a hybrid sample tray superimposing a flat glass pane on an aluminum plate processed with a black Alumite has been made. A sample is placed on the glass pane. However, ghosting is produced due to the reflection from the reverse of the glass pane and noise rises by irregular reflection. There are cases where unfavorable side effects are thus produced. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the aforementioned circumstances. Accordingly, it is an object of the present invention to provide a sample tray for an image information reader that is convenient to handle. 
     The sample tray of the present invention renders rinsing easy and can endure repeated use, by coating the placing surface of the sample tray with fluororesin. 
     That is, the sample tray according to the present invention is a sample tray on which a sample distributing specific organism-originated materials labeled with a fluorescent dye is placed and which is used in an image information reader having an excitation light source for emitting excitation light and photoelectric reading means for photoelectrically reading out fluorescence emitted from the fluorescent dye exited by the excitation light as a distributed image of the organism-originated materials in the sample and which employs the excitation light source, the sample tray, the sample, and the photoelectric reading means with an external light shield, wherein the sample tray has at least a surface on which the sample is placed coated with fluororesin. 
     Here, it is preferable that the fluororesin be, for example, a hybrid resin consisting of polytetrafluoroethylene (PTFE) and tetrafluoroethylene-perfluoroalkyl-vinylether copolymer (PFA) with a black color as a base. Specifically, it is preferable to employ Platinum stone (DuPont trademark (hereinafter omitted): Primer; 459-30170, Midocoat; 456-30270, Topcoat; 456-30370) with Silky Black (DuPont trademark (hereinafter omitted)) as a black pigment, 855-100 hybrid resin of PTFE and PFA (DuPont trademark (hereinafter omitted))with 855-023 industrial Primer (DuPont trademark (hereinafter omitted)) as a base, etc. In a conventional sample tray superimposing a glass pane on an aluminum plate processed with a black Alumite, ghosting from the glass pane or irregular reflection is mixed with fluorescence emitted from a sample and detected, so there is a limit in the case where fluorescent image information of high contrast is desired. On the other hand, for hybrid resin of PTFE and PFA with a black color as a base, there is no occurrence of ghosting or irregular reflection, because there is no need to superimpose a glass pane. As a result, fluorescent image information of high contrast can be acquired. 
     It is desirable for a user&#39;s convenience that depressed or projected markings representing a readable range of the photoelectric reading means be formed in the surface of the sample tray of the present invention on which a sample is placed. Particularly, in the case where an image information reader can vary the angle of field, that is, the case where a distance between the photoelectric reading means and the sample tray is variable, markings can be used as a standard when a user disposes a sample within a reading range suitable to a distance between both, if the markings are formed such that they are suitable to each reading range corresponding to each distance between both. The sample tray with markings is thus convenient to use. 
     Note that the markings formed in a depression or projection formed in a sample tray itself can acquire an image signal more accurately than painted markings. That is, there are cases where some of the paints to be used in marking emit fluorescence in no small amount. When a sample is irradiated with excitation light, in such a case, fluorescence emitted from the markings is mixed with fluorescence emitted from the fluorescent dye contained in the sample, so that the mixture is photoelectrically read out as a noise component. On the other hand, in the markings formed by the depressed or projected configurations of a sample tray itself without employing such paint, there is no occurrence of such local noise and therefore an image signal can be acquired accurately. 
     As a sample, various forms, such as a gel support body and a membrane filter, a micro-titre plate, and a slide glass transferring this gel thereon, can be employed if specific organism-oriented materials labeled with a fluorescent dye are distributed. 
     The sample-tray fabricating method according to the present invention is a method of fabricating a sample tray on which a sample distributing specific organism-originated materials labeled with a fluorescent dye is placed and which is used in an image information reader which is equipped with an excitation light source for emitting excitation light and photoelectric reading means for photoelectrically reading out fluorescence emitted from the fluorescent dye by the excitation light as a distributed image of the organism-originated materials in the sample and which employs the excitation light source, the sample tray, the sample, and the photoelectric reading means with external light shield, the method comprising the steps of: 
     coating at least a surface, on which the sample is placed, with fluororesin; and 
     forming depressed or projected markings, which represent a readable range of the photoelectric reading means, on the surface on which the sample is placed. 
     Note that it is preferable that the fluororesin be a hybrid resin consisting of polytetrafluoroethylene (PTFE) and tetrafluoroethylene-perfluoroalkyl-vinylether copolymer (PFA). 
     According to the sample tray of the present invention, the sample-placing surface is coated with fluororesin. Therefore, even if fluorescent dye, a sample, etc. have adhered to the sample-placing surface, these can be rinsed out by simple washing. Thus, the sample tray of the present invention is easy to handle and can sufficiently endure repeated use. 
     In addition, according to the sample fabricating method of the present invention, depressed or projected markings are formed after the fluororesin has been coated. Therefore, as compared with the case where fluororesin is coated after formation of the markings, the occurrence of unevenness in the fluororesin coat thickness in the marked portions and the vicinities is less likely and therefore there is an advantage of reducing the influence on read image information caused by unevenness in the thickness of the fluororesin coat. 
     Furthermore, the process of coating fluororesin requires annealing to be performed at 400° C. or so and this annealing process causes a sample tray to deform thermally. For this reason, after the annealing process, there is a need to correct this deformation by plastic deformation. However, since the aforementioned process of forming markings is performed after the coating process, the marking formation process and the thermal-deformation correcting process can be performed collectively. Thus, the number of processes can be reduced, compared with the case where a sample tray is fabricated in the order of the marking process, the coating process, and the correcting process. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects and advantages will become apparent from the following detailed description when read in conjunction with the accompanying drawings, wherein: 
     FIG. 1A is a perspective view illustrating a preferred embodiment of a sample tray of the present invention; 
     FIG. 1B is a cross sectional view taken along line  1 B— 1 B in FIG. 1A; 
     FIG. 2 is a schematic perspective view illustrating an example of an image information reader employing the sample tray shown in FIG. 1; and 
     FIG. 3 is a sectional view illustrating the essential parts of the image information reader shown in FIG.  2 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of a sample tray of the present invention will hereinafter be described with reference to the drawings. 
     FIGS. 1A and 1B show the preferred embodiment of the sample tray of the present invention, FIG. 2 shows an example of an image information reader employing the sample tray shown in FIGS. 1A and 1B, and FIG. 3 shows the interior of the image information reader shown in FIG.  2 . 
     In the sample tray  10  illustrated in FIGS. 1A and 1B, an aluminum plate  10   d , which is a base material, is coated with hybrid resin  10   c  consisting of PTFE and PFA with a black color as a base (see FIG.  1 B). More specifically, it is coated with Platinum Stone with Silky Black as a black pigment. 
     Also, the circumferential edge portion of the sample tray  10  rises upward and forms a flange  10   b . Furthermore, the flat portion other than the circumferential edge portion is provided with markings  10   a  indicating the readable range of a charged-coupled device (CCD)  51  that varies according to a location position with respect to an image information reader  100  to be described later, that is, a plurality of ranges, different in size, which hold a sample such as gel. After the aforementioned hybrid resin  10   c  has been coated, the markings  10   a  are formed by depressing small circles with respect to the surface on which a sample such as gel is placed. Note that the markings may be formed in projection form with respect to the placing surface. However, since there are cases where a sample strikes the projected markings and inclines, depressed markings are preferred. 
     On the other hand, the image information reader  100  illustrated in FIGS. 2 and 3 is provided with (1) the sample tray  10  of FIGS. 1A and 1B for holding gel  11  distributing specific organism-originated materials labeled with a fluorescent dye, within a black box  20  whose interior is shielded from light; (2) light-emitting diodes  45  for emitting excitation light to the gel  11  placed on the sample tray  10 ; (3) an interline-type CCD  51  with cooling elements for photoelectrically detecting florescence emitted from the fluorescent dye in the gel  11  by the excitation light and outputting an obtained image signal to an external image processor; (4) a lens  40  for projecting the image of the gel  11  on the sample tray  10  onto the light-receiving surface of the CCD  51 ; (5) a motor  32  for moving the lens  40  in the optical-axis direction; and (6) an excitation-light cut filter  46  with bands set such that florescence is transmitted but excitation light is not transmitted, the excitation-light cut filter being interposed between the CCD  51  and the lens  40 . 
     The main body  25  of the black box  20  is provided on both side surfaces of the interior wall thereof with 7 rails  21   a ,  21   b , . . . ,  21   g  for holding the sample tray  10 , the 7 rails each having a different distance from the lens  40 . The rear surface of the interior wall corresponding to the rails  21   a  to  21   g  is provided with sensors  22   a ,  22   b , . . . ,  22   g  for detecting whether or not the sample tray  10  is disposed on the rails  21   a  to  21   g . More specifically , the sensor  22   a  detects whether or not the sample tray  10  is placed on the rail  21   a  and the sensor  22   b  detects whether or not the sample tray  10  is placed on the rail  21   b . Similarly, the sensor  22   c  corresponds to the rail  21   c , the sensor  22   d  to the rail  21   d , the sensor  22   e  to the rail  21   e,  the sensor  22   f  to the rail  21   f,  and the sensor  22   g  to the rail  21   g.    
     The CCD  51  is provided to penetrate the top surface of the interior wall of the black box main body  25 , the lens  40  for projecting the image of the gel  11  onto the CCD  51  being moved by stages such that the stopped position (lens position) in the optical-axis direction X is at  41   a ,  41   b , . . . ,  41   g  in accordance with the rail  21   a ,  21   b , . . . ,  21   g  on which the sample tray  10  is placed. More specifically, the lens position  41   a  is a position suitable for projecting the image of the gel  11  on the sample tray  10  onto the CCD  51  when the sample tray  10  is placed on the rail  21   a . The lens position  41   b  is a position suitable for projecting the image of the gel  11  on the sample tray  10  onto the CCD  51  when the sample tray  10  is place don the rail  21   b . Likewise, the lens position  41   c  corresponds to the rail  21   c , the lens position  41   d  to the rail  21   d , the lens position  41   e  to the rail  21   e , the lens position  41   f  to the rail  21   f , and the lens position  41   g  to the rail  21   g . Note that the illustration of  41   d  to  41   f  has been omitted, and the markings  10   a  on the sample tray  10 , indicating a plurality of ranges different in size, correspond to the readable ranges of the CCD  51  in accordance with distances from the CCD  51  when the sample tray  10  is placed on each of the rails  21   a ,  21   b , . . . ,  21   g , respectively. 
     The movable lens  40  is moved to each of the aforementioned lens positions  41   a  to  41   g  by a stepping motor  32  provided inside the black box  20 . Input pulse numbers D 1 , D 2 , D 3 , D 4 , D 5 , D 6 , D 7  to the steeping motor  32 , respectively corresponding to the lens positions  41   a ,  41   b , . . . ,  41   g , are previously caused to correspond to the rails  21   a  to  21   g  and are stored as a reference table in a storage section  33  provided inside the black box  20 . 
     The interior of the black box  20  is further provided with focus control means  31  for receiving a result of detection, indicating any of the rails  22   a  to  22   g  that the sample tray  10  is placed on, from one of the sensors  22   a  to  22   g , also calculating the pulse number corresponding to the detection result by referring to the reference table stored in the storage section  33 , and inputting the calculated pulse number to the stepping motor  32 . 
     The outline operation of the image information reader  100  constructed as described above will hereinafter be described. 
     The gel  11  distributing specific organism-originated materials labeled with a fluorescent dye is first placed within a predetermined range on the sample tray  10 , by using the markings  10   a  as a standard. Then, the sample tray  10  with the gel  11  placed thereon is placed on one of the rails  21   a  to  22   g  of the image information reader  100  which is appropriate to the markings  10   a  in a range holding the gel  11 . The lens  40  has been stopped at a predetermined initial position. However, with placement of the sample tray  10 , the sensor  22   d , which corresponds to the rail on which the sample tray  10  was placed among the sensors  22   a  to  22   g  disposed within the black box  20  (e.g., the rail  21   d  in the fourth row), detects that the sample tray  10  has been placed and sends a detection signal to the focus control means  31 . At this time, there is no possibility that the other sensors  22   a  to  22   c  and  22   c  to  22   g  will output detection signals, because the sample tray  10  is not present on the corresponding rails  21   a  to  21   c  and  21   e  to  21   g.    
     The focus control means  31  receives the detection signal, recognizes that the detection signal was output from the sensor  22   d , obtains the pulse number D 4  corresponding to the sensor  22   d  by referring to the reference table, and inputs the pulse number D 4  to the stepping motor  32 . Based on the pulse number input from the focus control means  31 , the stepping motor  32  moves the lens  40  from the initial position to the lens position  41   d.    
     Here, the lens position  41   d  has previously been set as a position suitable for projecting the image of the gel  11  on the sample tray  10  onto the CCD  51  when the sample tray  10  is placed on the rail  21   d  of the fourth row. Therefore, the CCD  51  is in a position for suitably receiving an image of florescence that is emitted from the gel  11  on the sample tray  10  disposed on the rail  21   d  of the fourth row. 
     After the door of the black box  20  has been closed to shield light from the interior thereof, the gel  11  on the sample tray  10  is irradiated with the excitation light emitted from the LEDs  45 . The gel  11  irradiated with the excitation light emits florescence, because the fluorescent dye labeling specific organism-originated materials distributed inside the gel  11  is excited. The florescence emitted from the gel  11  is projected as the distributed image of the florescence on the gel  11  onto the light-receiving surface of the CCD  51  through the lens  40  and the excitation light cut filter  46 . 
     Here, the sample tray  10  has been coated with Platinum Stone  10   c  including, as a black pigment, Silky Black whose content of a fluorescent dye is less, compared with a conventional black Alumite process. Therefore, the florescence that is emitted from the sample tray  10  itself can be reduced to an extremely low level. 
     On the other hand, part of the excitation light emitted to the gel  11  is reflected at the surfaces of the gel  11 , the sample tray  10  or the like and travels in the direction of the CCD  51 . However, the excitation light cut filter  46  provided in front of the light-receiving surface of the CCD  51  prevents passage of excitation light and therefore there is no possibility that excitation light will be incident on the light-receiving surface of the CCD  51 . 
     The CCD  51  photoelectrically detects the image of the fluorescence emitted from the gel  11  and outputs an obtained signal to an external image processor, an external image display or the like. 
     If a sequence of image information reading operations described above ends, the door of the black box  20  is opened and the operator pulls out the sample tray  10  from the interior of the image information reader  100 . Then, the placed gel  11  is removed from the taken sample tray  10 . Thereafter, the sample tray  10  is rinsed with water or predetermined chemicals. Here, since the sample tray  10  is coated on the surface thereof with Platinum Stone  10   c , the fluorescent dye, the organism-originated materials, the gel or the like adhering to the placing surface can easily be rinsed out. Thus, the sample tray  10  is easier to handle than the conventional tray processed with a black Alumite and can be used repeatedly. 
     Note that the sample tray  10  of the preferred embodiment is provided with a plurality of markings indicating a plurality of sample-placing ranges different in size, because the sample tray  10  has been applied to the image information reader  100  having sample-tray disposing positions of multiple stages. Therefore, the present invention is not limited to this embodiment. For instance, in the case of a sample tray to be used in an image information reader whose readable range is always constant, the sample tray may be provided with only markings indicating a single sample-placing range or with no markings.