JP2008122487A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus having a simple constitution which is not complicated and also provides an excellent image free from image irregularity or an image defect. <P>SOLUTION: The image reading apparatus 100 reads an image recorded on a stimulable phosphor sheet 301 by irradiating the stimulable phosphor sheet 301 with exciting light L1 and photoelectrically converting stimulated luminescence L2 emitted therefrom. The stimulable phosphor sheet has a magnetic sheet 302 on an opposite surface side to its reading surface, and the apparatus 100 is equipped with a drive roller 202 having magnetic force. When reading the image, the stimulable phosphor sheet is attracted to the drive roller on its magnetic sheet side by the magnetic force, and the drive roller rotates at least once, whereby the stimulable phosphor sheet is conveyed nearly linearly in a subscanning direction H. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that reads an image recorded on a photostimulable phosphor sheet by photoelectrically converting photostimulated luminescence emitted by irradiating the photostimulable phosphor sheet with excitation light.

  Radiation images such as X-ray images are often used for disease diagnosis and the like. Conventionally, in order to obtain such a radiographic image, X-rays that have passed through a subject such as a patient are irradiated onto a phosphor layer (phosphor screen), thereby generating visible light, and this visible light is emitted to a normal photograph. In the same way as when taking a picture, a so-called radiograph was used in which a film using silver salt was irradiated and developed. However, in recent years, there has been devised a method for directly extracting an image from a phosphor layer without using a film coated with silver salt. As an example of this method, the radiation transmitted through the subject is absorbed by the phosphor, and then the phosphor is excited by light or thermal energy, so that the radiation energy accumulated by the phosphor is absorbed by the phosphor. Some radiate as fluorescence, and detect and image this fluorescence.

  For example, a photostimulable phosphor sheet having a photostimulable phosphor layer formed on a support is used, and the subject is irradiated with radiation transmitted through the subject to the photostimulable phosphor layer of the photostimulable phosphor sheet. Radiation energy corresponding to the radiation transmittance of each part is accumulated to form a latent image, and then the stimulable phosphor layer is scanned with stimulated excitation light to radiate the accumulated radiation energy of each part. This is converted into light, and the intensity of the light is converted into an image signal via a photoelectric conversion means such as a photomultiplier to obtain a radiographic image as digital image data.

  Based on such digital image data, an image is formed on a silver salt film, or an image is output to a monitor such as a CRT and visualized. The digital image data is stored in an image storage device such as a semiconductor storage device, a magnetic storage device, or an optical disk storage device, and then taken out from the image storage device as necessary, via a silver salt film, a CRT, or the like. Can be visualized.

  By the way, when the photostimulable phosphor sheet is scanned with the photostimulable excitation light, the photostimulable excitation light source must be precisely moved relative to the photostimulable phosphor sheet at a constant speed. For this reason, the following Patent Document 1 discloses a radiographic image in which a photostimulable phosphor plate is conveyed at a high speed and at a constant speed with a linear motion guide, a carriage and a drive roller, and a good radiographic image without image unevenness is obtained. A reader is disclosed.

  The principal part of the radiation image reading apparatus of Patent Document 1 is shown in FIG. In the radiographic image reading apparatus shown in FIG. 20, the photostimulable phosphor plate 10 is positioned on the carriage 11 with a rubber magnet or the like and fixed in the horizontal direction, and the carriage 11 is mounted on the linear motion guide 12, The moving guide 12 is configured to be movable in the horizontal direction while being guided by the linear guide rail 13. In order to carry out the sub-scanning conveyance of the photostimulable phosphor plate 10 in the horizontal direction, the driving roller 14 whose outer surface is made of a rubber material is brought into contact with the back surface 11a of the conveying table 11 and is driven to rotate by a motor. Are linearly moved in the sub-scanning direction together with the photostimulable phosphor plate 10 while being guided by the linear motion guide 12 and the linear motion guide rail 13. The stimulable phosphor plate 10 is irradiated with excitation light that is main-scanned in the direction perpendicular to the paper surface of FIG.

Patent Document 2 below discloses a configuration in which a sheet is conveyed while being sandwiched by two pairs of rotating rollers. Further, in Patent Document 3 below, a magnet is disposed at a fixed position along only a part in the circumferential direction on the inner peripheral surface of a hollow drum-shaped sheet holder that is rotatably supported. A sheet-holding body is provided in a state in which a stimulable phosphor sheet having a magnetic layer on the back surface is supplied to the outer peripheral surface of the portion where the magnet is disposed, and is adsorbed on the outer peripheral surface of the sheet holding body by the magnetic layer. A radiation image reading apparatus is disclosed that performs sub-scanning by rotating the.
JP 2004-212524 A JP 09-267949 A Japanese Patent Publication No. 05-81893

  However, the radiographic image reading apparatus of FIG. 20 attaches the photostimulable phosphor sheet to a rigid plate member such as a resin plate such as a cassette or a metal, and is fixed to the transport table 11 with a rubber magnet or the like. The moving guide 12, the linear guide rail 13, and the driving roller 14 are used to convey in the horizontal direction, and the configuration of the apparatus is complicated, and the conveyance table 11 and the linear guide 12 are expensive and have a large number of parts. Therefore, the cost of the apparatus is increased, and there is a problem that a very complicated fixing means / removing means is required to fix the photostimulable phosphor sheet to the transport table 11 alone.

  Further, in the case of a configuration in which the photostimulable phosphor sheet is sandwiched and conveyed by two pairs of rotating rollers as in Patent Document 2, it is necessary to vary the clamping force of the driven roller in order to obtain a good image. Therefore, a complicated roller holding mechanism is necessary. In addition, when the photostimulable phosphor sheet is nipped and transported by two pairs of rotating rollers, the sheet is transported with the drive roller and the driven roller being sandwiched between them, so that dust, dust, etc. can be removed from the photostimulable phosphor sheet. When adhering to the surface, there is a problem that the surface of the photostimulable phosphor sheet is damaged and an image defect is caused.

  Further, as in Patent Document 3, when the stimulable phosphor sheet is adsorbed on the outer peripheral surface of the portion where the magnet is disposed inside the sheet holding body with the magnetic layer, the stimulable phosphor sheet becomes a magnet on the outer peripheral surface. Therefore, the radius of the hollow drum-shaped sheet holder cannot be reduced, and the apparatus becomes large. Further, when the stimulable phosphor sheet is sub-scanned and conveyed by the rotation of the sheet holder, the position of the outer peripheral surface of the portion where the magnet is disposed changes, and accordingly, the adsorption position of the stimulable phosphor sheet is changed. Since the range changes and the positions of both ends thereof change, special means are required to hold both ends of the stimulable phosphor sheet, and the apparatus becomes complicated.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide an image reading apparatus that can obtain a good image with a simple configuration without image irregularities and image defects without being complicated. .

  In order to achieve the above object, the image reading apparatus according to the present invention records on the photostimulable phosphor sheet by photoelectrically converting the photostimulated luminescence emitted by irradiating the photostimulable phosphor sheet with excitation light. An image reading device for reading the image, wherein the photostimulable phosphor sheet has a magnetic sheet on the side opposite to the reading surface, and the image reading device includes a driving roller having magnetic force, At the time of reading, the photostimulable phosphor sheet is attracted to the drive roller by the magnetic sheet by a magnetic force, and the drive roller rotates at least once so that the photostimulable phosphor sheet is substantially linear in the sub-scanning direction. It is characterized by being configured to convey.

  According to this image reading apparatus, the stimulable phosphor sheet is conveyed in the sub-scanning direction by at least one rotation of the drive roller while the stimulable phosphor sheet is attracted to the drive roller having magnetic force. Without requiring expensive parts such as a moving guide or a transport table, the photostimulable phosphor sheet can be sub-scanned and transported with high accuracy with a simple configuration, and a good image free from image unevenness and image defects can be obtained. be able to.

  In the image reading apparatus, it is preferable that the driving roller includes a roller made of a magnetic material and a pair of magnets arranged so as to sandwich the roller. Thus, by arranging a pair of magnets at both ends of a roller made of a magnetic material, the position where the magnetic force distribution is maximized is near the center in the axial direction of the roller, so that the photostimulable phosphor sheet is stabilized on the roller. Since the magnetic flux density can be made uniform around the entire circumference of the roller, the suction force to the stimulable phosphor sheet during rotation of the roller can be kept constant, realizing high precision and stable sub-scan transport. Can contribute. In addition, a permanent magnet or an electromagnet can be used for a magnet.

  Moreover, it is preferable that the said roller has a friction layer which produces a frictional force with respect to the said stimulable fluorescent substance sheet in the outer peripheral surface. For example, a friction layer made of an elastic material such as a rubber material comes into contact with the photostimulable phosphor sheet, and the roller rotates to increase the frictional force in the sub-scanning direction of the photostimulable phosphor sheet. A slip or the like does not occur in the fluorescent phosphor sheet, which can contribute to the realization of highly accurate and stable sub-scanning conveyance.

  The outer diameter of the roller is preferably larger than the outer diameter of the magnet. As a result, the photostimulable phosphor sheet contacts the roller and does not contact the magnet when reading an image.

  Preferably, the drive roller has at least two rollers, and each of the rollers is disposed so as to be positioned at least in the vicinity of both ends of the photostimulable phosphor sheet. As a result, when the photostimulable phosphor sheet is transported, each roller of the drive roller is positioned at at least both ends of the photostimulable phosphor sheet, so that the photostimulable phosphor sheet is not bent and the photostimulable phosphor sheet is not bent. The stimulable phosphor sheet can be stably sub-scanned and conveyed.

  Preferably, the drive roller has at least three rollers, and the rollers are disposed in the vicinity of both end portions of at least two types of photostimulable phosphor sheets having different sizes. Accordingly, one roller can be shared by being positioned at one end of at least two types of photostimulable phosphor sheets having different sizes, and the other roller can be used for a large size photostimulable phosphor sheet. It is positioned at the other end, and another roller can be positioned at the other end of the small-sized photostimulable phosphor sheet. Therefore, regardless of the size of the photostimulable phosphor sheet, each roller of the drive roller is located at least at both ends of the photostimulable phosphor sheet, so that the photostimulable phosphor sheet is not bent and the photostimulable phosphor sheet is not bent. The stimulable phosphor sheet can be stably sub-scanned and conveyed.

  In addition, it is preferable to provide a guide plate that guides the photostimulable phosphor sheet on the magnetic sheet side when being conveyed in the sub-scanning direction. Thereby, the stimulable phosphor sheet can be stably guided when the stimulable phosphor sheet is conveyed. The guide plate is preferably made of a nonmagnetic material.

  In this case, the top of the drive roller preferably protrudes from the surface of the guide plate to the magnetic sheet side of the photostimulable phosphor sheet, and the photostimulable phosphor sheet can be reliably adsorbed to the drive roller, It is transported stably.

  The stimulable phosphor sheet is preferably conveyed in the sub-scanning direction in a flat state at least in the vicinity of the drive roller. Accordingly, the stimulable phosphor sheet can be linearly sub-scanned and conveyed in a flat state before and after the drive roller by rotating the drive roller at least once, so that the stimulable phosphor sheet is not curved or the like. Can be stably transported in the sub-scanning direction. The guide plate may be flat or curved as long as the photostimulable phosphor sheet can be sub-scanned and conveyed in a substantially straight line before and after the drive roller.

  Moreover, it is preferable that the sub scanning direction position which irradiates the said excitation light to the said photostimulable fluorescent substance sheet is a downstream position rather than the vertex position of the said driving roller, or the said vertex position. Thereby, the photostimulable phosphor sheet is stably conveyed with the rotation of the drive roller.

  Note that a plurality of the driving rollers may be arranged apart from each other in the sub-scanning direction.

  According to the image reading apparatus of the present invention, it is possible to realize a highly accurate and stable sub-scanning conveyance of the photostimulable phosphor sheet with a simple configuration without complication, and obtain a good image free from image unevenness and image defects. Can do.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view schematically showing a main part of the image reading apparatus according to the present embodiment. FIG. 2 is a side view of a main part schematically showing a main part of the image reading apparatus of FIG. FIG. 3 is a control block diagram showing the main part of the control system of the image reading apparatus of FIGS.

  In FIG. 1 and FIG. 2, illustration of a light shielding member that shields the entire apparatus from external light and a body cover that covers the apparatus body are omitted. Also, a transport mechanism that transports the photostimulable phosphor sheet to the reading unit of the apparatus main body is not shown.

  In the image reading apparatus according to the present embodiment, the radiation transmitted through the subject by radiography of the subject is absorbed by the photostimulable phosphor sheet, and a part of the energy is stored in the photostimulable phosphor as radiation image information. The information of the radiation image accumulated in the photostimulable phosphor is read by photoelectrically converting the photostimulated emission light generated by the irradiation of the photostimulated excitation light, and is used especially in the medical field where the subject is a patient. Is preferred.

  As shown in FIGS. 1, 2, and 3, the image reading apparatus 100 according to the present embodiment is configured to stimulate excitation of laser light or the like from the excitation excitation light source 51 (FIG. 3) to the stimulable phosphor sheet 301. The optical unit 110 that irradiates the light L1 and the stimulating light L2 generated by irradiation of the stimulating excitation light L1 from the stimulating excitation light source 51 to the stimulable phosphor sheet 301 is collected via the light guide plate 103. The light-emitting condensing tube 101 and the photoelectric converter 102 including a photomultiplier or the like that converts light from the stimulable light-emitting condensing tube 101 into an electric signal are provided.

  The optical unit 110 is configured to form an image of light emitted from the stimulating excitation light source 51 with an imaging lens and to perform main scanning in the x-axis direction of FIG. 1 with a deflection mirror such as a polygon mirror. It is fixed to a support base (not shown).

  The above-described optical unit 110 includes the light guide plate 103, the photostimulable light-emitting condenser tube 101, and the photoelectric converter 102 together with the light source 51, and constitutes the image reading unit 120 of FIG.

  As shown in FIG. 3, under the control of the control unit 50, the stimulating excitation light L <b> 1 is irradiated from the stimulating excitation light source 51, and the stimulated emission light L <b> 2 is photoelectrically converted by the photoelectric converter 102. The electrical signal from the signal passes through an A / D (analog / digital) conversion circuit 52 and is output as a radiation image signal, which is visualized by an external CRT or the like, stored in an image server, or a silver salt film Are exposed to a visible image.

  The photostimulable phosphor sheet 301 is usually accommodated in a box-shaped member such as a cassette, and when the cassette is loaded into the image reading apparatus, it is conveyed to the image reading unit 120 by a conveyance mechanism (not shown). It has become.

  As shown in FIG. 2, the photostimulable phosphor sheet 301 is a rectangular flat relatively thin plate, and the surface side reads the photostimulable phosphor layer 304 (FIG. 10) irradiated with photostimulated excitation light L1. A relatively thin magnetic sheet 302 made of magnetic stainless steel, steel, or the like is attached to the surface 301a opposite to the reading surface 301a with an adhesive member such as a double-sided adhesive tape.

  FIG. 10 schematically shows a cross-sectional configuration of the photostimulable phosphor sheet 301. As shown in FIG. 10, the stimulable phosphor sheet 301 has a stimulable phosphor layer 304 formed on a support member 305 such as a metal plate or a resin plate, and the magnetic sheet 302 is formed on the back surface 305 b side of the support member 305. Is attached. Since the photostimulable phosphor sheet 301 has relatively low rigidity, it is supported by the guide plate 201 in the horizontal direction.

  The image reading apparatus 100 in FIGS. 1 to 3 includes a sub-scanning transport mechanism 200 for transporting the photostimulable phosphor sheet 301 in the sub-scanning direction H that coincides with the y-axis direction in FIGS. The sub-scanning conveyance mechanism 200 includes a driving roller 202 extending in the x-axis direction and having a magnetic force so as to be attracted to the magnetic sheet 302 of the stimulable phosphor sheet 301 in the width direction, and a sub-scanning transport mechanism 200. And a flat guide plate 201 disposed so as to guide the magnetic sheet 302 of the photostimulable phosphor sheet 301 when being conveyed in the scanning direction H.

  1 and 2, the plane formed by the x axis and the y axis is a horizontal plane, and the guide plate 201 and the photostimulable phosphor sheet 301 are positioned substantially parallel to the horizontal plane.

  The guide plate 201 is divided in the sub-scanning direction H as shown in FIGS. 1 and 2, and the drive roller 202 is inserted in the gap 210 between the guide plates 201 and 201. The magnetic sheet 302 of the stimulable phosphor sheet 301. It arrange | positions so that it may contact | abut. The guide plate 201 is preferably made of a non-magnetic material such as resin or non-magnetic metal, and no attracting force is generated between the drive roller 202 and the magnetic sheet 302.

  The sub-scanning transport mechanism 200 further includes a motor 54 (FIG. 3) for rotationally driving the drive roller 202, a motor driver 53 (FIG. 3) for electrically driving the motor 54, and rotation of the motor 54. A motor pulley 205 connected to the shaft, a drive pulley 203 connected to the rotation shaft 504 of the drive roller 202, and a drive belt 204 stretched between the motor pulley 205 and the drive pulley 203 are provided.

  The motor 54 is controlled by the control unit 50 and rotated at a desired constant speed, so that the driving roller 202 attracted to the magnetic sheet 302 is rotated many times in the rotation direction r via the motor pulley 205, the driving belt 204, and the driving pulley 203. Thus, the photostimulable phosphor sheet 301 is conveyed in the sub-scanning direction H.

  Next, the drive roller 202 will be described with reference to FIGS.

  FIG. 4 is a perspective view schematically showing the drive roller of FIGS. FIG. 5 is a cross-sectional view of the drive roller of FIG. 4 taken along the line VV. FIG. 6 is a diagram schematically showing a magnetic force distribution by a combination of one roller and a pair of magnets arranged at both ends of the driving roller of FIG. FIG. 7 is a diagram schematically showing a magnetic force distribution by a combination of a plurality of rollers and a pair of magnets arranged at both ends of the driving roller of FIG.

  As shown in FIGS. 4 and 5, the driving roller 202 includes a rotation shaft 504, a plurality of rollers 501 a, 501 b, 501 c fixed to the rotation shaft 504, and the rollers 501 a to 501 c so as to sandwich the rollers 501 a to 501 c. And circular magnets 401 a, 401 b, 401 c, and 401 d that are fixed to the rotary shaft 504. For example, the magnets 401a to 401d are arranged so that the left end in FIG. 4 is an N pole and the right end is an S pole, and the rollers 501a to 501c are arranged so as to be sandwiched between the N pole and the S pole of the magnet.

  In addition, as shown in FIG. 4, when the rollers 501a to 501c and the magnets 401a to 401d are connected, the roller and the magnet can be arranged in a relationship of (N + 1) magnets to N rollers. The magnets 401a to 401d are permanent magnets, but may be electromagnets.

  As shown in FIG. 5, each of the rollers 501a to 501c has a magnetic roller 503 made of a magnetic material such as magnetic stainless steel, and a friction elastic layer 502 made of a rubber material or the like coated on the outer peripheral surface of the magnetic roller 503. . When the rollers 501a to 501c rotate while the frictional elastic layer 502 is in contact with the photostimulable phosphor sheet 301, a frictional force is generated in the transport direction.

  Since the outer diameters of the rollers 501a to 501c are larger than the outer diameters of the magnets 401a to 401d, the photostimulable phosphor sheet 301 is brought into contact with and attracted to the rollers 501a to 501c by the magnetic sheet 302.

  When the rollers 501a, 501b, and 501c are fixed to the rotating shaft 504 in FIGS. 4 and 5, a plurality of screw holes 503d and 503e are formed in the radial direction of the magnetic roller 503 as shown in FIG. It can be configured to be fixed to the shaft 504 with a screw. Further, the magnetic roller 503 may be fixed to the rotating shaft 504 using an adhesive.

  As shown in FIG. 6, according to the combination of one roller 501a and a pair of magnets 401a and 401b disposed at both ends of the driving roller 202 in FIG. 4, the magnets 401a and 401b are disposed at both left and right ends of the magnetic roller 503. Thus, the position where the magnetic force distribution is maximized can be set near the center in the axial direction of the roller 501a having a high friction coefficient, so that the photostimulable phosphor sheet 301 can be stably adsorbed and conveyed by the roller 501a. Further, since the magnetic flux density can be made uniform over the entire circumference of the roller 501a, the adsorption force to the photostimulable phosphor sheet 301 during the rotation of the roller 501a can be kept constant.

  Further, as shown in FIG. 7, the combination of a plurality of rollers 501a to 501c and a pair of magnets 401a to 401d arranged at each of the left and right ends thereof corresponds to a combination of a plurality of combinations of FIG. Since the position where the distribution is maximized can be near the center in the axial direction of the rollers 501a to 501c having a high friction coefficient, the photostimulable phosphor sheet 301 can be stably adsorbed and conveyed by the plurality of rollers 501a to 501c.

  4, the stimulable phosphor sheet 301 is moved in the sub-scanning direction H by rotating the drive roller 202 while the stimulable phosphor sheet 301 is attracted to the drive roller 202 by a magnetic force. Can be transported. In this case, since the frictional elastic layer 502 on the outer peripheral surface of the drive roller 202 contacts the photostimulable phosphor sheet 301, the frictional force in the transport direction with respect to the photostimulable phosphor sheet 301 can be increased, and the photostimulability is enhanced. The phosphor sheet 301 is not slipped and can be stably conveyed.

  Further, the position in the sub-scanning direction H where the stimulating excitation light L1 is irradiated on the reading surface 301a of the photostimulable phosphor sheet 301 is coincident with the apex of the driving roller 202 as shown in FIG. As described above, the downstream side in the sub-scanning direction H is preferable. Thereby, the photostimulable phosphor sheet 301 is stably conveyed with the rotation of the driving roller 202.

  The relative positional relationship between the drive roller 202 and the guide plate 201 in the vertical direction of the plane of the guide plate 201 is such that the top of the drive roller 202 slightly protrudes upward in the drawing from the guide plate 201 as shown in FIG. It is preferable to configure as described above. As a result, the photostimulable phosphor sheet 301 can be reliably brought into contact with and adsorbed to the magnetic sheet 302. The protrusion amount d of the top portion of the driving roller 202 from the surface of the guide plate 201 is preferably about 0.1 to 0.2 mm. If the reading position is not the top portion of the driving roller 202, the excitation is performed within this range. Since it is within the depth of the light L1, there is no problem of defocusing. Since the photostimulable phosphor sheet 301 has a relatively low rigidity, it is supported by the guide plate 201 at portions other than the image reading unit 120 as shown in FIG.

  Next, an example in which a plurality of rollers in the drive roller of FIG. 4 are arranged corresponding to the widthwise dimension of the photostimulable phosphor sheet will be described with reference to FIGS.

  FIG. 8 is a front view showing the arrangement positions of a plurality of rollers in the drive roller of FIG. FIG. 9 is a front view for explaining a case where a photostimulable phosphor sheet of another size is conveyed by a plurality of rollers arranged as shown in FIG.

  The drive roller 202A shown in FIGS. 8 and 9 has the same number of rollers as the drive roller 202 of FIG. 4, but a plurality of stimuli having different width dimensions when arranging the plurality of rollers 501a to 501c. The positions of the rollers 501a to 501c in the x-axis direction are adjusted so as to correspond to the phosphor sheet.

  That is, the photostimulable phosphor sheet 601 to be conveyed in FIG. 8 has the same configuration as the photostimulable phosphor sheet 301 described above, but is, for example, a half-cut size and a width dimension in the x-axis direction of 14 inches. . As shown in FIG. 8, the roller 501c at the right end of the x axis in the drawing of the driving roller 202A is disposed corresponding to the right end 601a of the stimulable phosphor sheet 601, and the roller 501a at the left end of the x axis is the stimulable phosphor sheet 601. Are arranged corresponding to the left end 601b.

  Further, the photostimulable phosphor sheet 602 to be transported in FIG. 9 has the same configuration as the photostimulable phosphor sheet 301 described above, but is, for example, a six-cut size and a width dimension in the x-axis direction of 10 inches. is there. As shown in FIG. 9, the roller 501c of the driving roller 202A is positioned corresponding to the right end 602a of the stimulable phosphor sheet 602, and the roller 501b near the center of the x-axis corresponds to the left end 602b of the stimulable phosphor sheet 602. Are arranged.

  Further, as shown in FIGS. 8 and 9, the plurality of rollers 501a to 501c of the driving roller 202A are arranged apart from each other, so that a pair of magnets 401a and 401b are arranged at the left and right ends of the roller 501a, and the roller 501b. A pair of magnets 401c and 401d are disposed at the left and right ends of the roller 501 and a pair of magnets 401e and 401f are disposed at the left and right ends of the roller 501c.

  According to the driving roller 202A shown in FIGS. 8 and 9, when the photostimulable phosphor sheet 601 having a relatively large width dimension is sub-scanned and transported for image reading as shown in FIG. 8, the photostimulable phosphor sheet is used. In the case where the photostimulable phosphor sheet 602 having a relatively small width as shown in FIG. 9 is sub-scanned and conveyed for image reading as shown in FIG. 9 while adsorbing to the rollers 501a, 501b and 501c near the left and right ends and near the center. The photostimulable phosphor sheet 602 is adsorbed to the two rollers 501b and 501c at the left and right ends.

  As described above, in the driving roller 202A of FIGS. 8 and 9, the positions of the plurality of rollers 501a, 501b, and 501c in the x-axis direction correspond to the end positions of the photostimulable phosphor sheets 601 and 602 having different width dimensions. Thus, both the photostimulable phosphor sheets 601 and 602 having different width dimensions can be held in contact with and adsorbed to the plurality of rollers 501a to 501c at the left and right ends. The sheet can be stably transported in the sub-scanning direction.

  Next, an image reading operation of the image reading apparatus 100 according to the present embodiment will be described. First, the photostimulable phosphor sheet 301 is pulled out from a cassette loaded in the image reading apparatus by a conveying mechanism (not shown), taken into the image reading apparatus, and conveyed to the image reading unit 120 (FIG. 2). The

  As shown in FIGS. 1 and 2, the photostimulable phosphor sheet 301 is in a predetermined sub-scanning (y-axis) position on the guide plate 201, and the motor 54 in FIG. The phosphor sheet 301 is sub-scanned and conveyed at a constant speed in the sub-scanning direction H, and the stimulable phosphor sheet 301 is irradiated with the stimulating excitation light L1 main-scanned in the x-axis direction from the optical unit 110. At this time, a light emission phenomenon occurs according to the latent image from the photostimulable phosphor layer 304 (FIG. 10) on the surface 301 a of the photostimulable phosphor sheet 301, and thus the photostimulated emitted light L <b> 2 is received by the light receiving surface 103 a of the light guide plate 103. The stimulated emission light L2 is guided to the photostimulated luminescence collector tube 101 by the light guide plate 103, condensed by the photostimulated luminescence collector tube 101, converted into an electric signal by the photoelectric converter 102, and A / D. A radiation image signal is obtained through the conversion circuit 52.

  When the photostimulable phosphor sheet 301 is sub-scanned and conveyed to a predetermined sub-scanning position and the image reading operation is completed, the stimulable phosphor sheet 301 is again stored in the cassette by the conveying mechanism (not shown), and the cassette is discharged from the inside of the apparatus.

  When the photostimulable phosphor sheet 301 is sub-scanned and conveyed by many rotations of the drive roller 202 described above, the photostimulable phosphor sheet 301 has a magnetic sheet 302 attached to the side opposite to the reading surface 301a. Therefore, the sheet is conveyed while being continuously attracted to the driving roller 202 by the magnetic force from the driving roller 202. For this reason, the sub-scanning conveyance mechanism of the photostimulable phosphor sheet 301 does not require a complicated configuration such as a conveyance table, a linear motion guide, a holding roller, and the like, and the photostimulable phosphor sheet is formed by a simple configuration. Sub-scan transport can be performed with high accuracy and stability, and a good diagnostic image without image unevenness and image defects can be obtained.

  Further, since the stimulable phosphor sheet 301 can be flatly and linearly sub-scanned and conveyed by rotating the driving roller 202 many times, the outer diameters of the rollers 501a to 501c of the driving roller 202 can be made relatively small. The stimulable phosphor sheet 301 can be conveyed without being bent, and there is no risk of damage to the stimulable phosphor sheet 301.

  Further, the frictional elastic layer 502 provided on the outer peripheral surfaces of the rollers 501a to 501c of the driving roller 202 can increase the frictional force in the conveying direction of the photostimulable phosphor sheet 301. Therefore, it is possible to stably convey the sheet without slipping and the like, which can contribute to the realization of highly accurate and stable sub-scanning conveyance.

  Next, a preferred modification of the present embodiment will be described with reference to FIGS.

  FIG. 13 is a side view of an essential part schematically showing a configuration in which a drive roller is added to FIGS. As shown in FIG. 13, a driving roller 212 having the same configuration as that of the driving roller 202 is arranged apart from the driving roller 202 in the sub-scanning direction H, and the driving rollers 202 and 212 are rotated many times so The phosphor sheet 301 can be transported flatly and in a straight line. In this case, the position in the sub-scanning direction H at which the excitation light L1 is irradiated on the reading surface 301a of the photostimulable phosphor sheet 301 is between the vertex of the driving roller 202 and the vertex of the driving roller 212 as shown in FIG. It is preferable to be within the range m. As a result, the photostimulable phosphor sheet 301 is stably conveyed as the drive rollers 202 and 212 rotate. In addition, you may add a drive roller further in FIG. In addition, it is preferable to provide a guide member that supports the photostimulable phosphor sheet 301 within the range m in FIG. 13. In this case, the guide member is preferably disposed so as not to protrude from the drive rollers 202 and 212.

  FIG. 14 is a front view showing an example in which the outer diameter of the central roller in the drive rollers of FIGS. 8 and 9 is reduced. As shown in FIG. 14, the outer diameter of the roller 501b between the rollers 501a and 501c of the driving roller 202A of FIGS. 8 and 9 is reduced, and the vertex of the roller 501b does not protrude from the tangent line n that contacts the vertex of the rollers 501a and 501c. It is like that. The outer diameter of the roller 501b is preferably about 0.1 to 0.15 mm smaller than the outer diameter of the rollers 501a and 501c, for example. Accordingly, the photostimulable phosphor sheet 601 having a relatively large width shown in FIG. 8 can be stably conveyed in a sub-scanning manner while preventing bending during conveyance. In FIG. 14, when the photostimulable phosphor sheet 602 having a relatively small width dimension is conveyed as shown in FIG. 9, the photostimulable phosphor sheet 602 is attracted to the rollers 501 b and 501 c obliquely, but image reading is performed. By performing density correction in subsequent image processing, the density unevenness in the width direction and the distance between the light receiving surface 103a of the light guide plate 103 in FIG. 2 and the surface 301a of the stimulable fluorescent layer 304 (FIG. 10) are changed. The resulting effect can be corrected to such an extent that it cannot be recognized on the image, and the effect of oblique suction can be removed.

  FIG. 15 is a main part side view showing an example in which the photostimulable phosphor sheet 301 of FIGS. 1 and 2 is aligned and aligned in the sub-scanning direction H before the start of sub-scanning conveyance. As shown in FIG. 15, an abutting member 215 is disposed in the upstream gap 210 in the sub-scanning direction H between the driving roller 202 and the guide plate 201 so as to prevent the photostimulable phosphor sheet 301 from being conveyed. The contact member 215 is moved up and down by the drive unit 216. When the photostimulable phosphor sheet 301 is pulled out of the cassette loaded in the image reading apparatus and conveyed by a conveyance mechanism (not shown), the leading end 301b of the photostimulable phosphor sheet 301 is moved as shown in FIG. By contacting the contact member 215, the photostimulable phosphor sheet 301 is aligned and aligned just before the drive roller 202 at the tip 301b. After the alignment, the contact member 215 is retracted in the downward direction u by the drive unit 216, so that the aligned photostimulable phosphor sheet 301 can be sent to the drive roller 202, and the photostimulable phosphor sheet 301 is aligned. Can be sub-scanned.

  In addition, it is preferable to arrange | position the contact member 215 of FIG. 15 in the width direction (perpendicular direction of the paper surface of FIG. 15) both ends of the stimulable phosphor sheet 301. Moreover, the drive part 216 can be comprised from an electromagnetic valve, for example, and can be controlled according to the conveyance timing of the photostimulable phosphor sheet 301 by the control part 50 as shown in FIG.

  FIG. 16 is a main part side view showing an example in which the guide plate of FIGS. 1 and 2 is curved. As shown in FIG. 16, the guide plate 201 </ b> A is configured as a concave curved surface on both the upstream side and the downstream side, and has a radius R centering on the center of curvature s. The photostimulable phosphor sheet 301 is conveyed along a concave curved surface having a radius R, and is conveyed substantially linearly in the horizontal direction in the vicinity of the front and rear of the driving roller 202. By comprising in this way, an apparatus can be comprised short in the horizontal direction of a figure, and the whole apparatus can be made compact.

  FIG. 17 is a side view of an essential part showing another example in which the guide plate of FIGS. 1 and 2 is curved. In the example of FIG. 17, horizontal portions 217 and 218 are provided on the upstream and downstream sides of the guide plate 201 </ b> A with the drive roller 202 interposed therebetween in the configuration of FIG. 16. Thereby, the photostimulable phosphor sheet 301 is conveyed linearly in the horizontal direction in the horizontal range t on both sides of the driving roller 202 in the sub-scanning direction H.

  Next, a modified example of the drive roller will be described with reference to FIG. FIG. 18 is a longitudinal sectional view of an essential part showing a modification of the drive roller of FIG. As shown in FIG. 18, in the driving roller 501d, the magnetic roller 503a has cylindrical portions 503b and 503c that are thinner than the roller portion 505 on the left and right, and a pair of magnets 401g and 401h are disposed on the cylindrical portions 503b and 503c. The roller portion 505 is positioned and sandwiched. A friction elastic layer 502 is formed on the outer peripheral surface of the roller portion 505, and the magnetic roller 503 a is fixed to the rotating shaft 504. 4 may be provided with a plurality of such rollers 501d. The outer diameter of the roller portion 505 of the magnetic roller 503a is the same as or smaller than the outer peripheral surface of the magnets 401g and 401h.

  As described above, the best mode for carrying out the present invention has been described. However, the present invention is not limited to these, and various modifications are possible within the scope of the technical idea of the present invention. For example, the size of the photostimulable phosphor sheet is not limited to the size as shown in FIG. 8 and FIG. 9, but may be other sizes. What is necessary is just to arrange | position each roller in the position which can hold | maintain both ends of a fluorescent substance sheet.

  Further, in the photostimulable phosphor sheet 301 of FIG. 10, the photostimulable phosphor layer 304 may be formed on the magnetic sheet 302 so that the magnetic sheet 302 also serves as a support member, and the support member 305 may be omitted.

  1 and 2, the photostimulable phosphor sheet 301 is conveyed in the horizontal direction, but may be configured to be sub-scanned and conveyed in a vertical direction or a direction inclined with respect to the horizontal direction.

1 is a perspective view schematically showing a main part of an image reading apparatus according to the present embodiment. FIG. 2 is a side view of a principal part schematically showing a principal part of the image reading apparatus in FIG. 1. FIG. 3 is a control block diagram illustrating a main part of a control system of the image reading apparatus in FIGS. 1 and 2. FIG. 3 is a perspective view schematically showing the drive roller of FIGS. 1 and 2. FIG. 5 is a cross-sectional view of the drive roller of FIG. 4 taken along the line VV. FIG. 5 is a diagram schematically showing a magnetic force distribution by a combination of one roller and a pair of magnets arranged at both ends of the driving roller in FIG. 4. FIG. 4 is a diagram schematically showing a magnetic force distribution by a combination of a plurality of rollers and a pair of magnets arranged at both ends of the driving roller in FIG. 3. FIG. 5 is a front view showing the arrangement positions of a plurality of rollers in the driving roller of FIG. 4 (viewed from a direction orthogonal to the sub-scanning conveyance direction). It is a front view for demonstrating the case where the photostimulable fluorescent substance sheet of another size is conveyed with the some roller arrange | positioned like FIG. It is a figure which shows schematically the cross-sectional structure of the photostimulable phosphor sheet | seat of FIG. 1, FIG. It is a principal part side view for demonstrating the preferable position of the subscanning direction H which irradiates the stimulating excitation light L1 to the reading surface of a stimulable fluorescent substance sheet in this Embodiment. It is a principal part side view for demonstrating the preferable relative positional relationship of the drive roller and guide plate in the perpendicular | vertical direction of the plane of a guide plate in this Embodiment. It is a principal part side view which shows roughly the structure which added the drive roller in FIG. 1, FIG. FIG. 10 is a front view showing an example in which the outer diameter of the roller at the central portion is reduced in the drive rollers of FIGS. 8 and 9. FIG. 3 is a side view of an essential part showing an example in which the photostimulable phosphor sheets of FIGS. 1 and 2 are aligned and aligned in the sub-scanning direction H before the start of sub-scanning conveyance. It is a principal part side view which shows the example which made the guide plate of FIG.1, FIG.2 into the shape of a curved surface. It is a principal part side view which shows another example which made the guide plate of FIG.1, FIG.2 into the shape of a curved surface. FIG. 5 is a longitudinal sectional view of a main part showing a modification of the drive roller in FIG. 4. FIG. 6 is a cross-sectional view of an essential part showing a structure in which a roller is screwed to the rotating shaft of FIGS. 4 and 5. It is a principal part side view which shows roughly the principal part of the radiographic image reading apparatus of patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 50 Control part 51 Photoexcitation light source 54 Motor 100 Image reader 101 Photoluminescent light collection tube 102 Photoelectric converter 110 Optical unit 120 Image reading part 200 Sub-scanning conveyance mechanism 201 Guide plates 202 and 212 Drive roller 202A Drive roller 301 Bright Excitable phosphor sheet 301a surface, reading surface 301b tip 302 Magnetic sheets 401a, 401b, 401c, 401d, 401e, 401f Magnets 501a, 501b, 501c Roller 502 Friction elastic layer (friction layer)
503 Magnetic roller 504 Rotating shafts 601 and 602 Stimulable phosphor sheets 501d of different sizes Roller 503a Magnetic rollers 401g and 401h Magnet H Sub-scanning direction L1 Stimulated excitation light L2 Stimulated emission light

Claims (10)

An image reading device that reads an image recorded on the photostimulable phosphor sheet by photoelectrically converting photostimulated luminescence emitted by irradiating the photostimulable phosphor sheet with excitation light,
The photostimulable phosphor sheet has a magnetic sheet on the side opposite to the reading surface,
The image reading device includes a driving roller having magnetic force,
When the image is read, the photostimulable phosphor sheet is attracted by the magnetic sheet to the driving roller by a magnetic force, and the driving roller rotates at least once so that the photostimulable phosphor sheet is substantially moved in the sub-scanning direction. An image reading apparatus configured to be conveyed linearly.   The image reading apparatus according to claim 1, wherein the driving roller includes a roller made of a magnetic material and a pair of magnets arranged so as to sandwich the roller.   The image reading apparatus according to claim 2, wherein the roller has a friction layer that generates a frictional force against the photostimulable phosphor sheet on an outer peripheral surface thereof.   The image reading apparatus according to claim 2, wherein an outer diameter of the roller is larger than an outer diameter of the magnet. The drive roller has at least two of the rollers,
The image reading apparatus according to claim 2, 3 or 4, wherein each of the rollers is disposed so as to be positioned in the vicinity of at least both ends of the photostimulable phosphor sheet. The drive roller has at least three of the rollers,
5. The image reading apparatus according to claim 2, 3, or 4, wherein each of the rollers is disposed in the vicinity of each end of at least two types of photostimulable phosphor sheets having different sizes.   The image reading apparatus according to claim 1, further comprising a guide plate that guides the photostimulable phosphor sheet on the magnetic sheet side when the stimulable phosphor sheet is conveyed in the sub-scanning direction.   The image reading apparatus according to claim 7, wherein a top of the driving roller protrudes from a surface of the guide plate toward the magnetic sheet side of the stimulable phosphor sheet.   9. The image reading apparatus according to claim 1, wherein the photostimulable phosphor sheet is conveyed in the sub-scanning direction in a flat state at least in the vicinity of the driving roller.   The image according to any one of claims 1 to 9, wherein a position in the sub-scanning direction in which the excitation light is applied to the photostimulable phosphor sheet is a vertex position of the driving roller or a downstream side of the vertex position. Reader.

Images