JP2005221544A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus where image information is accurately read or recorded by avoiding a situation that vibration caused on the inside and the outside of the apparatus is transmitted to an image recording carrier. <P>SOLUTION: When a storage type phosphor sheet IP on which radiation image information is recorded is moved from a photographing position to a reading position, the lower end of the sheet IP is supported by vibration damping members 14a and 14b fixed in a bracket 12. A reading and erasing unit 40 is carried to perform scanning in such a state, whereby the radiation image information is read in a state where the sheet IP is not rocked. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus that moves an image record carrier to a scanning position and reads or records image information by a scanning unit that is scanned and conveyed by a scanning mechanism.

  For example, after recording radiographic image information of a subject on a stimulable phosphor sheet disposed at a photographing position, the stimulable phosphor sheet is irradiated with excitation light in the main direction, and the stimulable phosphor sheet is irradiated with the stimulable light. There is known a radiation image information recording / reading apparatus configured to read the stimulated emission light emitted from the phosphor sheet by a reading unit that is conveyed in a direction substantially orthogonal to the main direction (see Patent Document 1).

  The stimulable phosphor sheet is a part of the radiation energy when irradiated with radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.), and later laser light or visible light. It is a sheet formed by applying a storage phosphor that exhibits stimulated light emission corresponding to energy stored by irradiating excitation light such as a layer.

JP 2003-280121 A

  In this case, after moving the stimulable phosphor sheet from the photographing position to the reading position, in the device that scans and conveys the reading unit and reads the radiation image information, the driving mechanism for conveying the reading unit and the air conditioning in the device When the stimulable phosphor sheet swings due to vibrations generated by the mechanism or vibrations outside the apparatus, unevenness may occur in the sub-direction of the read image. Even in the case of a scanner device that reads image information carried on a document, the same problem may occur due to the swinging of the document.

  The present invention has been made to solve the above-described problems, and avoids a situation in which vibration generated inside and outside the apparatus is transmitted to the image record carrier, and performs reading or recording of image information with high accuracy. An object of the present invention is to provide an image forming apparatus capable of performing the above.

The present invention includes a moving mechanism that moves the image record carrier to a scanning position, a scan unit that scans the image record carrier to read image information, or a scanner that scans the image record carrier to record image information, and the image In an image forming apparatus comprising a scanning mechanism that scans and conveys the scanning unit with respect to a record carrier
The image recording carrier disposed at the scanning position and moved to the scanning position by the moving mechanism is supported by a fixed portion via a vibration damping member.

  In this case, the vibration generated inside and outside the apparatus and transmitted through the fixed portion is attenuated by the vibration attenuation member, and the vibration of the image record carrier or the scanning portion supported by the vibration attenuation member is suitably suppressed.

The vibration damping member uses the mass m of the image recording carrier, the spring coefficient k of the vibration damping member, the scanning conveyance speed v of the image recording carrier by the scanning mechanism, and the upper limit value fs of the spatial frequency at which the unevenness of the image information is visually recognized. ,
v · √ (m / k)> √2 / (2π · fs)
By selecting and setting a characteristic satisfying the above relationship, it is possible to read or record image information while reliably attenuating vibration.

  According to the image forming apparatus of the present invention, it is possible to avoid a situation in which vibration generated inside and outside the apparatus is transmitted to the image record carrier, and to read or record image information with high accuracy.

  FIG. 1 shows a schematic configuration of a radiation image information recording / reading apparatus 20 to which the image forming apparatus of the present invention is applied. The radiographic image information recording / reading apparatus 20 includes a support column 24 erected on a support base 22 and a main body portion 26 supported by the support column 24 so as to be movable up and down.

  The front part of the housing 28 that constitutes the main body 26 is an imaging table 32 on which the subject 30 is positioned. The imaging table 32 is provided with a phototimer 36 for measuring the dose of X-rays irradiated from the radiation source 34 through the subject 30 and controlling the irradiation amount, and a grid 38 for removing scattered rays.

  Inside the main body 26, a stimulable phosphor that can move in the direction of the arrow between a recording position (solid line) close to the imaging table 32 and a reading position (two-dot chain line) separated from the imaging table 32. A sheet IP (image record carrier) is disposed. The stimulable phosphor sheet IP stores a part of the radiation energy when irradiated with radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.). It is a sheet having a stimulable phosphor layer that exhibits stimulated light emission according to energy accumulated by irradiating excitation light such as light.

  In addition, a reading / erasing unit 40 that moves in the vertical direction along the front surface of the stimulable phosphor sheet IP disposed at a position indicated by a two-dot chain line is disposed inside the main body 26. The reading / erasing unit 40 irradiates the stimulable phosphor sheet IP with the excitation light L, and photoelectrically reads the stimulated emission light P output in accordance with the intensity of the accumulated radiation energy (scanning). And an erasing unit 44 for irradiating the storable phosphor sheet IP from which the radiation image information has been read with erasing light to remove the remaining radiation energy.

  The reading unit 42 includes a plurality of laser diodes 41a to 41x that output the excitation light L, and a plurality of CCD line sensors 43a to 43e that convert the stimulated emission light P obtained from the stimulable phosphor sheet IP into electrical signals. Is provided. The erasing unit 44 includes a plurality of cold cathode tubes 45a to 45m that output erasing light.

  The reading / erasing unit 40 is configured to be long in a direction (main direction) orthogonal to a moving direction (sub direction) indicated by an arrow in FIG. The laser diodes 41 a to 41 x housed in the reading unit 42 are arranged at predetermined intervals along the longitudinal direction of the reading unit 42 so as to irradiate the reading unit 42 with the line-shaped excitation light L. Also, three CCD line sensors 43a, 43c and 43e and two CCD line sensors 43b and 43d are arranged in a staggered manner below and above the laser diodes 41a to 41x.

  2 shows a state in which the stimulable phosphor sheet IP is arranged at the recording position indicated by the solid line in FIG. 1, and FIG. 3 shows the state in which the stimulable phosphor sheet IP is arranged at the reading position indicated by the two-dot chain line in FIG. Indicates the state. In this case, vibration attenuating members 14a and 14b attached to the bracket 12 (fixed portion) fixed to the housing 28 of the main body portion 26 are disposed at the reading position. These vibration damping members 14a and 14b support the lower end of the stimulable phosphor sheet IP moved to the reading position. As the vibration damping members 14a and 14b, for example, chloroprene rubber or the like can be used, and one having a spring coefficient set based on a relational expression described later is selected.

  Brackets 50a and 50b are disposed on both sides in the longitudinal direction of the reading unit 42, and these brackets 50a and 50b extend in the vertical direction along both sides of the stimulable phosphor sheet IP. Engages with rails 49a and 49b. Conveying belts 46a and 46b (scanning mechanism) are disposed along the guide rails 49a and 49b. Brackets 47a and 46b disposed on both sides of the erasing unit 44 are provided on the conveying belts 46a and 46b, respectively. 47b is engaged. The conveyor belts 46a and 46b are driven by a read / erase unit moving motor 48 (FIG. 1) disposed substantially at the center of the main body 26, and move the read / erase unit 40 in the vertical direction along the guide rails 49a and 49b. To do.

  FIG. 4 shows the configuration of the stimulable phosphor sheet IP and the configuration of the moving mechanism 51 that moves the stimulable phosphor sheet IP.

  The stimulable phosphor sheet IP is a rectangular sheet that is stored and held in a standing state in the main body portion 26, and the stimulable phosphor layer is formed on the image recording surface 52. Engagement members 54a to 54d formed with semicircular recesses are fixed to both upper and lower sides of the stimulable phosphor sheet IP. Leaf spring members 64a to 64d held by holders 66a to 66d are mounted on the upper portions of the respective engagement members 54a to 54d.

  Positioning plates 76a to 76d for positioning the stimulable phosphor sheet IP at the reading position are fixed below the respective engaging members 54a to 54d. As shown in FIG. 4, each of the positioning plates 76 a to 76 d contacts the positioning rollers 82 a to 82 d provided on the frames 80 a and 80 b of the main body 26, thereby positioning the stimulable phosphor sheet IP at the reading position. . In addition, notches 84a and 84b are formed at the center of both sides of the stimulable phosphor sheet IP for the operator to hold the stimulable phosphor sheet IP.

  On the other hand, the storage mechanism 51 for the stimulable phosphor sheet IP includes an IP movement motor 86. An upper drive shaft 92 is connected to the drive shaft 88 of the IP movement motor 86 via a belt 90, and a lower driven shaft 94 is connected to the upper drive shaft 92 via a belt 93. The lower ends of the drive plates 96a to 96d are fixed to both ends of the upper drive shaft 92 and the lower driven shaft 94. Intermediate portions of L-shaped link members 98a to 98d are pivotally supported on upper end portions of the drive plates 96a to 96d.

  As for link members 98a-98d, cam rollers 100a-100d are pivotally supported by one end. Each of the cam rollers 100a to 100d is formed on the guide plates 102a to 102d, and engages with cam grooves 104a to 104d that are curved from the upper part to the lower part of the main body part 26. Further, the other end portions of the link members 98a and 98b and the other end portions of the link members 98c and 98d are connected by support shafts 106a and 106b that support the back surface portion of the stimulable phosphor sheet IP, respectively. Bearing members 110a to 110d are engaged with both ends of the support shafts 106a and 106b. As shown in FIG. 2, these bearing members 110 a to 110 d engage with concave portions of the engaging members 54 a to 54 d of the stimulable phosphor sheet IP. The bearing members 110a to 110d engaged with the engaging members 54a to 54d are held by the engaging members 54a to 54d by the leaf spring members 64a to 64d, whereby the stimulable phosphor sheet IP is connected to and supported by the moving mechanism 51. The

  The radiation image information recording / reading apparatus 20 of the present embodiment is basically configured as described above. Next, the operation and effect of the apparatus will be described.

  First, the case where radiation image information is recorded on the stimulable phosphor sheet IP will be described. In this case, the reading / erasing unit 40 stands by at the lower end position shown in FIG. 1, and the stimulable phosphor sheet IP is moved to the recording position shown in FIG.

  That is, when the IP movement motor 86 is driven, the upper drive shaft 92 and the lower driven shaft 94 are rotated via the belts 90 and 93, and the drive plates 96a to 96d having one end fixed to both ends are shown in FIG. It rotates in the direction of arrow A shown. As the drive plates 96a to 96d rotate, the cam rollers 100a to 100d of the link members 98a to 98d pivotally supported on the other ends of the drive plates 96a to 96d move along the cam grooves 104a to 104d of the guide plates 102a to 102d. To do. Accordingly, the bearing members 110a to 110d connected to the link members 98a to 98d move to the imaging table 32 side. In this case, the bearing members 110a to 110d are engaged with the engaging members 54a to 54d fixed to the stimulable phosphor sheet IP, and move the stimulable phosphor sheet IP to the recording position shown in FIG.

  After the stimulable phosphor sheet IP is disposed at the recording position, the recording of the radiation image information is started.

  Therefore, the main body 26 is moved up and down along the support column 24 in accordance with the imaging region of the subject 30, and then the radiation source 34 is activated to irradiate the subject 30 with X-rays. The X-rays transmitted through the subject 30 are irradiated to the stimulable phosphor sheet IP through the phototimer 36 and the grid 38, whereby the radiographic image information of the subject 30 is recorded on the stimulable phosphor sheet IP.

  After the radiation image information is recorded, the stimulable phosphor sheet IP is moved from the recording position to the reading position shown in FIG. That is, when the IP movement motor 86 is driven and the drive plates 96a to 96d rotate in the direction of arrow B shown in FIG. 2, the link members 98a to 98d are guided and moved by the guide plates 102a to 102d, and the bearing member 110a. With ~ 110d, the stimulable phosphor sheet IP moves to the reading position.

  When the stimulable phosphor sheet IP moves to the reading position, the positioning plates 76a to 76d fixed to both sides of the stimulable phosphor sheet IP come into contact with the positioning rollers 82a to 82d, and thereby the stimulable phosphor sheet IP. Is accurately positioned at the reading position.

  Further, vibration damping members 14a and 14b fixed to the bracket 12 are disposed at the reading position. Accordingly, when the stimulable phosphor sheet IP moves to the reading position, the lower end portion of the stimulable phosphor sheet IP is supported by the vibration damping members 14a and 14b as shown in FIG.

  In this case, the stimulable phosphor sheet IP is supported by the moving mechanism 51, and if the belt 93 and the link members 98a to 98d constituting the moving mechanism 51 are bent or rattled, the stimulable phosphor sheet. The IP may swing with respect to the reading / erasing unit 40. However, since the drive mechanism constituting the radiation image information recording / reading apparatus 20 and vibrations from outside the apparatus are suitably attenuated by the vibration attenuation members 14a and 14b as described later, the stimulable phosphor sheet IP is It is supported in a very good state without swinging.

  After the stimulable phosphor sheet IP is arranged at the reading position, the reading / erasing unit moving motor 48 is driven, the reading / erasing unit 40 is raised by the conveying belts 46a and 46b, and reading of the radiation image information by the reading unit 42 is started. Is done.

  Therefore, the line-shaped excitation light L output from the laser diodes 41a to 41x constituting the reading unit 42 is irradiated onto the stimulable phosphor sheet IP, and the brightness corresponding to the radiation energy accumulated from the stimulable phosphor sheet IP is obtained. Exhaust light P is output. The stimulated emission light P is guided to the CCD line sensors 43a to 43e, and the CCD line sensors 43a to 43e convert the introduced stimulated emission light P into an electrical signal. This electrical signal is subjected to predetermined signal processing and then transmitted to an external image processing apparatus (not shown). The reading unit 42 moves up the guide rails 49a and 49b to scan the stimulable phosphor sheet IP, and the radiation image information recorded on the entire surface is read two-dimensionally. In this case, since the stimulable phosphor sheet IP is supported in a good state without being swung by the vibration damping members 14a and 14b, the radiation image information can be read with extremely high accuracy.

  After the reading / erasing unit 40 moves to the upper end position and the reading of the radiation image information from the stimulable phosphor sheet IP by the reading unit 42 is completed, the reading / erasing unit 40 starts to descend, and the erasing process by the erasing unit 44 is performed. Done. The erasing unit 44 irradiates the stimulable phosphor sheet IP with the erasing light output from the cold cathode fluorescent lamps 45a to 45m. The remaining radiation energy is emitted from the stimulable phosphor sheet IP irradiated with the erasing light. This process is continued until the reading / erasing unit 40 moves to the lower end position, and the entire erasing process of the stimulable phosphor sheet IP is completed.

  Here, the setting of the characteristics of the vibration damping members 14a and 14b that can suitably suppress the swing of the stimulable phosphor sheet IP will be described.

When the mass of the stimulable phosphor sheet IP including the engaging members 54a to 54d is m and the spring coefficient of the vibration damping members 14a and 14b is k, the natural frequency fn of the stimulable phosphor sheet IP is
fn = 1 / (2π) · √ (k / m) (1)
It is expressed. On the other hand, if the vibration frequency of the read / erase unit 40 is f, the frequency ratio u between the stimulable phosphor sheet IP and the read / erase unit 40 is:
u = f / fn (2)
The vibration transmissibility Tr from the read / erase unit 40 to the stimulable phosphor sheet IP is
Tr = | 1 / (1-u ² ) | (3)
It is expressed. FIG. 5 is a graph showing the relationship between the frequency ratio u expressed by the equation (3) and the vibration transmissibility Tr.

  In this case, in order to reduce the swing of the stimulable phosphor sheet IP due to the vibration of the reading / erasing unit 40, it is necessary to make the vibration transmissibility Tr smaller than 1 (the range of the hatched portion in FIG. 5). Therefore, in order to obtain the vibration-proofing effect by the vibration damping members 14a and 14b, Tr <1 and u> √2 from the equation (3).

Therefore, if the upper limit value of the spatial frequency at which the unevenness of the radiation image information is visually recognized is fs, and the conveyance speed in the sub direction of the read / erase unit 40 is v, the vibration frequency f of the read / erase unit 40 at the upper limit value fs is
f = v · fs (4)
It becomes. Therefore, from the condition of u> √2, the spring coefficient k of the vibration damping members 14a and 14b is
v · √ (m / k)> √2 / (2π · fs) (5)
It is sufficient to select from the characteristics satisfying the above relationship.

  By selecting and setting the vibration attenuating members 14a and 14b based on the equation (5), the oscillation frequency of the stimulable phosphor sheet IP due to the vibration of the apparatus including the reading / erasing unit 40 is less than the upper limit value fs. Therefore, the radiographic image information can be read without any unevenness.

1 is a schematic configuration diagram of a radiation image information recording / reading apparatus to which an image forming apparatus of the present invention is applied. FIG. 2 is a perspective explanatory view showing a state in which a stimulable phosphor sheet is arranged at a recording position in the radiation image information recording / reading apparatus shown in FIG. 1. FIG. 2 is a perspective explanatory view showing a state in which a stimulable phosphor sheet is arranged at a reading position in the radiation image information recording / reading apparatus shown in FIG. 1. FIG. 2 is a perspective configuration diagram of a stimulable phosphor sheet mounted on the radiation image information recording / reading apparatus shown in FIG. 1 and a moving mechanism thereof. FIG. 3 is an explanatory diagram of the relationship between the vibration ratio and the vibration transmissibility of the stimulable phosphor sheet and the reading / erasing unit in the radiation image information recording / reading apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 ... Bracket 14a, 14b ... Vibration damping member 20 ... Radiation image information recording / reading device 26 ... Main-body part 30 ... Subject 40 ... Reading erasing unit 51 ... Moving mechanism IP ... Storage phosphor sheet

Claims (2)

A moving mechanism that moves the image record carrier to a scanning position, scans the image record carrier to read image information, or scans the image record carrier to record image information, and the image record carrier An image forming apparatus including a scanning mechanism that scans and conveys the scanning unit.
An image forming apparatus, wherein the image recording carrier disposed at the scanning position and moved to the scanning position by the moving mechanism is supported by a fixed portion via a vibration damping member. The apparatus of claim 1.
The vibration attenuating member includes a mass m of the image record carrier, a spring coefficient k of the vibration attenuating member, a scanning conveyance speed v of the image record carrier by the scanning mechanism, and an upper limit fs of a spatial frequency at which unevenness of image information is visually recognized. Using,
v · √ (m / k)> √2 / (2π · fs)
An image forming apparatus characterized by selecting and setting one having characteristics satisfying the above relationship.

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