Patent Publication Number: US-6984199-B2

Title: Sheet member guide mechanism having presser members for retaining a fabric tube fitted over a roller core

Description:
This is a division of application Ser. No. 09/984,840, now U.S. Pat. No. 6,730,009, filed Oct. 31, 2001, the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sheet member guide mechanism having a guide roller for guiding a sheet member. 
     2. Description of the Related Art 
     There is known a system for recording radiation image information of a subject such as a human body with a stimulable phosphor, and reproducing the recorded radiation image information on a photosensitive medium such as a photographic film, or displaying the recorded radiation image information on a display unit such as a CRT or the like. 
     The stimulable phosphor is a phosphor which, when exposed to a radiation (X-rays, α-rays, γ-rays, electron beams, ultraviolet radiation, or the like), stores a part of the energy of the radiation, and, when subsequently exposed to stimulating rays such as visible light, emits light in proportion to the stored energy of the radiation. Usually, a sheet provided with a layer of the stimulable phosphor is used as a stimulable phosphor sheet. 
     The above known system includes an image information reading apparatus which comprises a reading unit for reading the recorded radiation image information carried on the stimulable phosphor sheet, and an erasing unit for erasing residual radiation image information remaining on the stimulable phosphor sheet after the recorded radiation image information has been read from the stimulable phosphor sheet. The image information reading apparatus also includes a loading unit for accommodating a cassette which stores a stimulable phosphor sheet with the radiation image information of a subject being recorded thereon by an external exposure device. 
     When the cassette is opened, a sheet picking mechanism removes the stimulable phosphor sheet from the cassette, and the stimulable phosphor sheet is fed to the reading unit by a sheet feed mechanism. The reading unit reads the recorded radiation image information from the stimulable phosphor sheet. Thereafter, the erasing unit erases residual radiation image information from the stimulable phosphor sheet, which is then stored back into the cassette in the loading unit. 
     There has recently been a demand for efficiently reading the energy stored in a stimulable phosphor sheet in order to reproduce the recorded radiation image information of a subject with high image quality. Such a demand is particularly growing in the field of mammography or the like. One attempt to meet the demand is to use a transparent base in a stimulable phosphor sheet. When stimulating light is applied to the outer surface of a phosphor layer (recording surface) of the stimulable phosphor sheet, light is emitted from both surfaces of the phosphor sheet, i.e., light is emitted is from the outer surface of the phosphor layer and the outer surface of the transparent base (reverse surface). Therefore, the stimulable phosphor sheet serves as a double-side-readable stimulable phosphor sheet. 
     The sheet feed mechanism employs a roller for preventing the stimulable phosphor sheet from rising off a curved feed path to smoothly guide the stimulable phosphor sheet along the curved feed path. The roller has a damping member applied to an area thereof which will be contacted by the reverse surface or recording surface of the stimulable phosphor sheet. The damping member is effective to prevent the reverse surface or recording surface of the stimulable phosphor sheet from being damaged by contact with the roller. 
     The damping member is attached to the roller by an adhesive tape or the like. However, the adhesive tape fails to keep the damping member bonded smoothly to the entire surface of the roller. In order to bond the damping member smoothly to the entire surface of the roller, it is necessary to repeatedly detach and bond the damping member. As a result, the process of attaching the damping member appropriately to the roller is considerably complex. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a sheet member guide mechanism which has a simple structure and is capable of feeding a sheet member smoothly and reliably along a desired feed path without causing damage to the sheet member. 
     According to the present invention, there is provided a sheet member guide mechanism comprising a guide roller for guiding a sheet member which is being fed, the guide roller comprising a roller core and a fabric tube fitted under pressure over the roller core. Since it is not necessary to attach the fabric tube to the outer circumferential surface of the roller core by an adhesive tape or the like, the guide roller can be assembled highly efficiently. The fabric tube is woven or knit of fibers such as nylon filaments or the like, so that there is no joint formed in the outer circumferential surface of the fabric tube, and hence the fabric tube which is held against a sheet member does not cause damage to the sheet member. 
     The sheet member guide mechanism also has a pair of pressers mounted respectively in axial ends of the roller core to hold and secure respective ends of the fabric tube in the axial ends of the roller core. The ends of the fabric tube are kept out of sliding contact with the sheet member, and are prevented from being unraveled. 
     The roller core comprises a hollow roller which is rotatably supported on a shaft by a pair of bearings. Therefore, even if foreign deposits such as dust particles are applied to the fabric tube, since the fabric tube does not slide against the sheet member, the sheet member is effectively prevented from being damaged by those foreign deposits. 
     The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a vertical cross-sectional view of an image information reading apparatus which incorporates a sheet member guide mechanism according to the present invention; 
         FIG. 2  is an exploded perspective view of the sheet member guide mechanism; 
         FIG. 3  is a longitudinal cross-sectional view of the sheet member guide mechanism; and 
         FIG. 4  is an elevational view showing the manner in which the sheet member guide mechanism operates when the image information reading apparatus is scanning a sheet member. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows in vertical cross section an image information reading apparatus  10  which incorporates a sheet member guide mechanism according to the present invention. 
     As shown in  FIG. 1 , the image information reading apparatus  10  has an apparatus housing  12  which houses therein a cassette loading unit  16  for loading a cassette  14  which stores therein a stimulable phosphor sheet S as a sheet-like recording medium on which the radiation image information of a subject or the like is temporarily recorded, a reading unit  18  for applying a laser beam L as stimulating light to the stimulable phosphor sheet S to photoelectrically read the recorded radiation image information from the stimulable phosphor sheet S, an erasing unit  20  for erasing residual radiation image information from the stimulable phosphor sheet S after the desired recorded radiation image information has been read from the stimulable phosphor sheet S, and a sheet member guide mechanism  21  disposed near the reading unit  18 . 
     The cassette  14  comprises a casing  22  for housing the stimulable phosphor sheet S therein, and a lid  24  openably and closably mounted on an end of the casing  22  for allowing the stimulable phosphor sheet S to be removed from and inserted into the casing  22 . The cassette loading unit  16  includes a lid opening means (not shown) for opening and closing the lid  24  and a sheet picking means  28  having suction cups  26  for attracting and removing the stimulable phosphor sheet S from the cassette  14  and also returning the stimulable phosphor sheet S back into the cassette  14  after recorded image information has been read and residual image information has been erased. 
     The erasing unit  20  and the reading unit  18  are positioned downstream of the sheet picking means  28  and connected thereto by a reciprocating feed system  30 . The reciprocating feed system  30  comprises a plurality of roller pairs  32  that make up a vertical feed path extending from the cassette loading unit  16  and a horizontal feed path extending from the lower end of the vertical feed path. The erasing unit  20  is disposed on the vertical feed path. The reading unit  18  is disposed above the horizontal feed path. A laterally sheet shifting unit  33  and the sheet member guide mechanism  21  are disposed in the vicinity of a boundary between the vertical feed path and the horizontal feed path. The erasing unit  20  comprises has a vertical array of erasing light sources  34 . The erasing unit  20  may have a single erasing light source, and the erasing light source or sources may extend vertically. 
     The laterally sheet shifting unit  33  comprises a pair of rollers  36   a ,  36   b  for temporarily gripping the leading end of the stimulable phosphor sheet S in the direction in which it is fed, and a pressing means (not shown) for moving the stimulable phosphor sheet S in a direction transverse to the direction in which the stimulable phosphor sheet S is fed, thereby to laterally position the stimulable phosphor sheet S. 
     As shown in  FIGS. 2 and 3 , the sheet member guide mechanism  21  has a guide roller  38 . The guide roller  38  comprises a hollow roller (roller core)  44  rotatably supported on a shaft  140  by a pair of bearings  42   a ,  42   b , a woven or knit fabric tube  46  fitted under pressure over the hollow roller  44 , and a pair of pressers  50   a ,  50   b  mounted in respective axial ends of the holler roller  44  to secure ends  48   a ,  48   b  of the fabric tube  46  in the axial ends of the hollow roller  44 . A clearance C is provided between each of the pressers  50   a ,  50   b  and the shaft  40 . 
     The fabric tube  46  is made of fibers such as nylon filaments which do not damage the stimulable phosphor sheet S and which are woven or knit into a tubular form. Specifically, the fabric tube  46  may be a pipe unit “FJ20PIP” manufactured by Nakamura Sengyo, for example. 
     The fabric tube  46 , which is stretchable and contractible, has an inside diameter smaller than the outside diameter of the hollow roller  44  and an axial length larger than the axial length of the hollow roller  44 . However, the fabric tube  46  may have an inside diameter equal to or greater than the outside diameter of the hollow roller  44 . At any rate, when the fabric tube  46  is fitted over the hollow roller  44 , the fabric tube  46  is pressed against the outer circumferential surface of the hollow roller  44 . 
     The ends  48   a ,  48   b  of the fabric tube  46  are heat-pressed for protection against being unraveled. Therefore, the ends  48   a ,  48   b  of the fabric tube  46  are thicker than the remaining portion of the fabric tube  46 . 
     The pressers  50   a ,  50   b  have respective flanges  52   a ,  52   b , respective larger-diameter portions  54   a ,  54   b  integrally extending coaxially from the flanges  52   a ,  52   b , and respective smaller-diameter portions  56   a ,  56   b  integrally extending coaxially from the larger-diameter portions  54   a ,  54   b . The pressers  50   a ,  50   b  are press-fitted into the respective axial ends of the hollow roller  44  with the smaller-diameter portions  56   a ,  56   b  pressing the thicker ends  48   a ,  48   b  of the fabric tube  46  against inner circumferential surface regions of the hollow roller  44 , and the larger-diameter portions  54   a ,  54   b  pressing other portions of the fabric tube  46  against inner circumferential surface regions of the hollow roller  44 . Spacers  58   a ,  58   b  are mounted on the shaft  40  against the respective outer axial ends of the pressers  50   a ,  50   b , and E-rings  59   a ,  59   b  are also mounted on the shaft  40  axially outwardly of the spacers  58   a ,  58   b.    
     As shown in  FIG. 1 , the reading unit  18  has an auxiliary scanning feed mechanism  60  for reciprocally feeding the stimulable phosphor sheet S horizontally in the directions indicated by the arrow X, a laser beam applying mechanism  62  which applies a laser beam L as simulating light vertically downwardly in the direction indicated by the arrow Y to the stimulable phosphor sheet S which is being fed in the auxiliary scanning direction indicated by the arrow X 1 , and a reading mechanism  64  for collecting light emitted from the stimulable phosphor sheet S to photoelectrically read the radiation image information recorded in the stimulable phosphor sheet S. 
     The laser beam applying mechanism  62  has an optical system  66  for bending the laser beam L which has been emitted horizontally in a substantially vertically downward direction to apply the laser beam L to the stimulable phosphor sheet S. The reading unit  18  also includes a light guide  68  and a reflecting mirror  70  that are positioned near the area where the laser beam L is applied to the stimulable phosphor sheet S. The light guide  68  serves to collect and guide the light that is emitted from the stimulable phosphor sheet S upon exposure to the laser beam L. The reading unit  18  also has a photomultiplier  72  mounted on the upper end of the light guide  68 . 
     The auxiliary scanning feed mechanism  60  has first and second feed roller pairs  74 ,  76  for gripping the stimulable phosphor sheet S to feed the stimulable phosphor sheet S in the direction indicated by the arrow X 1  (auxiliary scanning direction) and the direction indicated by the arrow X 2 . 
     Operation of the image information reading apparatus  10  will be described below with respect to the sheet member guide mechanism  21  according to the present invention. 
     The cassette  14  is horizontally loaded into the cassette loading unit  16  that is positioned in an upper portion of the apparatus housing  12 . The cassette  14  stores therein the stimulable phosphor sheet S with the radiation image information of a subject such as a human body being recorded thereon. The lid  24  of the loaded cassette  14  is opened by the lid opening/closing means (not shown) in the cassette loading unit  16 . 
     Then, the sheet picking means  28  is actuated to move the suction cups  26  into the cassette  14 , and the suction cups  26  attract a surface (reverse surface) of the stimulable phosphor sheet S in the cassette  14 . The suction cups  26  which have attracted the stimulable phosphor sheet S are moved from within the cassette  14  toward the reciprocating feed system  30 , thus removing the stimulable phosphor sheet S from the cassette  14 . Substantially at the same time that the leading end of the stimulable phosphor sheet S removed from the cassette  14  is gripped by the first roller pair  32 , the suction cups  26  release the stimulable phosphor sheet S. 
     The roller pairs  32  are rotated to feed the stimulable phosphor sheet S horizontally and then vertically downwardly along the vertical feed path of the reciprocating feed system  30 . After the stimulable phosphor sheet S has passed through the erasing unit  20 , the stimulable phosphor sheet S is fed into the laterally sheet shifting unit  33 . The laterally sheet shifting unit  33  laterally positions the stimulable phosphor sheet S laterally, i.e., in a direction perpendicular to the direction in which the stimulable phosphor sheet S is fed. Thereafter, the rollers  36   a ,  36   b  are moved away from each other, and the leading end of the stimulable phosphor sheet S is fed to the auxiliary scanning feed mechanism  60  of the reading unit  18 . 
     In the auxiliary scanning mechanism  60 , the stimulable phosphor sheet S is gripped by the first and second roller pairs  74 ,  76  and fed horizontally in the auxiliary scanning direction indicated by the arrow X 1 . At the same time, the laser beam L is emitted from the laser beam applying mechanism  62 . The laser beam L first travels horizontally and then is directed downwardly as indicated by the arrow Y by the optical system  66 . The laser beam L is applied to the recording surface of the stimulable phosphor sheet S to scan the stimulable phosphor sheet S in a main scanning direction. In response to the application of the laser beam L, the recording surface of the stimulable phosphor sheet S emits light representing the recorded radiation image information. The emitted light is applied to the light guide  68  directly or by the reflecting mirror  70 , and then guided by the light guide  68  to the photomultiplier  72 , which photoelectrically reads the radiation image information based on the light. 
     As shown in  FIG. 4 , the recording surface of the stimulable phosphor sheet S is guided in contact with the guide roller  38  of the sheet member guide mechanism  21 . As shown in  FIG. 3 , the fabric tube  46  is fitted under pressure over the hollow roller  44  of metal. The fabric tube  46  is held in direct contact with the stimulable phosphor sheet S, and the hollow roller  44  with the fabric tube  46  fitted thereover is rotated around the shaft  40  by the bearings  42   a ,  42   b  as the stimulable phosphor sheet S moves. 
     Since the fabric tube  46  is woven or knit of nylon filaments or the like, there is no joint formed in the outer circumferential surface of the fabric tube  46 , and hence the fabric tube  46  held against the stimulable phosphor sheet S does not cause damage to the stimulable phosphor sheet S. 
     As described above, the fabric tube  46  is fitted under pressure over the hollow roller  44 . Specifically, if the inside diameter of the fabric tube  46  is smaller than the outside diameter of the hollow roller  44 , then when the hollow roller  44  is axially pushed into the fabric tube  46 , the fabric tube  46  is press-fitted over the hollow roller  44 . After the axial ends of the fabric tube  46  are pushed into the respective axial ends of the hollow roller  44 , the pressers  50   a ,  50   b  are pressed into the axial ends of the hollow roller  44 . The ends  48   a ,  48   b  of the fabric tube  46  are thus held in the respective axial ends of the hollow roller  44  by the pressers  50   a ,  50   b.    
     Alternatively, if the inside diameter of the fabric tube  46  is equal to or greater than the outside diameter of the hollow roller  44  and the axial length of the fabric tube  46  is the same as the axial length of the hollow roller  44 , then the ends  48   a ,  48   b  of the fabric tube  46  are forcibly pulled apart and pushed into the respective axial ends of the hollow roller  44 , and then the pressers  50   a ,  50   b  are pressed into the respective axial ends of the hollow roller  44 . Since the fabric tube  46  is contracted radially inwardly by being axially pulled, the fabric tube  46  is press-fitted over the hollow roller  44 . 
     At any rate, the fabric tube  46  is not required to be attached to the hollow roller  44  by an adhesive tape or the like, and the guide roller  48  can be assembled highly efficiently. 
     The hollow roller  44  is rotatably supported on the shaft  40  by the bearings  42   a ,  42   b . Therefore, even when foreign deposits such as dust particles are applied to the fabric tube  46 , since the fabric tube  46  does not slide against the stimulable phosphor sheet S, the recording surface (phosphor layer) of the stimulable phosphor sheet S is effectively prevented from being damaged by those foreign deposits. 
     As the ends  48   a ,  48   b  of the fabric tube  46  are held within the respective axial ends of the hollow roller  44 , the ends  48   a ,  48   b  are not exposed out of the hollow roller  44  and hence are not brought into sliding contact with the stimulable phosphor sheet S. Therefore, fibers such as nylon filaments are prevented from being unraveled from the ends  48   a ,  48   b  of the fabric tube  46 . Furthermore, since the ends  48   a ,  48   b  are made thicker by heat-pressing, they are effectively prevented from being displaced out of the hollow roller  44  when the pressers  50   a ,  50   b  are pressed into the axial ends of the hollow roller  44 . 
     The pressers  50   a ,  50   b  may not be pressed into the axial ends of the hollow roller  44 , but may be fixed to the axial ends of the hollow roller  44  by an adhesive, for example. 
     After the radiation image information has been read from the stimulable phosphor sheet S, the auxiliary scanning feed mechanism  60  is reversed to feed the stimulable phosphor sheet S back to the reciprocating feed system  30 . At this time, the stimulable phosphor sheet S is guided by the guide roller  38  of the sheet member guide mechanism  21 , and the guide roller  38  operates in the same manner as described above. 
     The stimulable phosphor sheet S is fed upwardly as indicated by the arrow A through the reciprocating feed system  30  into the erasing unit  20 . In the erasing unit  20 , the erasing light sources  34  are energized to remove residual radiation image information from the stimulable phosphor sheet S. Thereafter, the stimulable phosphor sheet S is returned into the cassette  14 , and the lid  24  is closed. The cassette  14  is unloaded from the cassette loading unit  16 , and then the stimulable phosphor sheet S is processed to record next radiation image information. 
     In the present embodiment, the sheet member guide mechanism  21  is disposed near the laterally sheet shifting unit  33  and downstream of the reading unit  18 . The sheet member guide mechanism  21  may include a guide roller  38  positioned at a curved feed path between the vertical and horizontal feed paths of the reciprocating feed system  30 . If a double-side-readable stimulable phosphor sheet is used for mammography or the like, then the sheet member guide mechanism  21  should preferably be positioned in a required region on the feed paths in order to prevent damage to both surfaces of the stimulable phosphor sheet. 
     The guide roller  38  includes the hollow roller  44  rotatably supported on the shaft  40  and the fabric tube  46  fitted over the hollow roller  44 . The guide roller  38  may be constructed as a drive roller which is driven to rotate. In such a modification, the fabric tube  46  is fitted under pressure over a solid roller (roller core) that is connected to a rotary drive source, and ring-shaped grooves are defined in respective ends of the drive roller out of its shank, with the pressers  50   a ,  50   b  pressed or bonded into the ring-shaped grooves. 
     With the sheet member guide mechanism according to the present invention, since the fabric tube is fitted under pressure over the roller core, no joint is formed in the fabric tube, and the fabric tube does not need to be attached to the roller core by an adhesive tape or the like. The sheet member guide mechanism is thus capable of preventing damage to the sheet member, and the guide roller can be assembled highly efficiently. 
     Although a certain preferred embodiment of the present invention has been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.