JPH0465580B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a device that reads image information by scanning excitation light two-dimensionally on a stimulable phosphor sheet on which image information is accumulated and recorded, and particularly in the return path of reciprocating main scanning. The present invention relates to an image scanning reading device that erases lines.

Certain types of fluorophores are exposed to radiation (X-rays, α-rays, β-rays,
When irradiated with γ-rays, ultraviolet rays, etc., a part of this radiation energy is accumulated in the phosphor, and when this phosphor is irradiated with excitation light such as visible light, the phosphor increases depending on the accumulated energy. is known to exhibit stimulated luminescence, and phosphors exhibiting this property are called stimulable phosphors.

Using this stimulable phosphor, radiation image information of a human body, etc. is stored on a sheet having a layer of stimulable phosphor (hereinafter referred to as a ``stimulable phosphor sheet'' or simply ``sheet''). This stimulable phosphor sheet is scanned with excitation light such as a laser beam to generate stimulated luminescent light, and the resulting stimulated luminescent light is read out photoelectrically to obtain an image signal. The applicant has already proposed a radiation image recording/reading system that outputs a visible image to a recording material such as a photographic light-sensitive material, CRT, etc. based on the above. (Unexamined Japanese Patent Publication 1983)
-12429, 56-11395, etc. ) The image scanning/reading device in this radiation image recording/reading system scans a stimulable phosphor sheet two-dimensionally using a laser beam or the like as excitation light, and then uses photoelectric detection of the stimulated luminescent light emitted at that time. A method is adopted in which image signals are obtained by detecting images in time series using a device. Two-dimensional scanning at this time is performed by performing main scanning and sub-scanning on the sheet using excitation light, but for this purpose, generally, the sheet is moved in one direction to perform sub-scanning, and the sheet is moved in the direction of movement. Main scanning is performed by reciprocating the excitation light in a perpendicular direction.

A commonly used means for performing this main scanning includes a galvanometer mirror that reciprocates along a fixed trajectory at a fixed speed. Since the sub-scanning is performed continuously at a constant speed, the scanning line drawn on the stimulable phosphor sheet by this main scanning means is a polygonal line having a fixed angle with respect to the direction perpendicular to the sub-scanning direction. It is formed in a shape (pine needle-like). In this case, since the diameter of the light beam is a certain size, the scanning lines overlap at the point where the scanning is switched from forward scanning to backward scanning or vice versa. Especially when trying to perform high-precision reading by increasing the scanning line density,
Since each round trip scan line is scanned close to each other, the amount of overlap between the scan lines is increased. A stimulable phosphor sheet has the property that once it is irradiated with excitation light and emits stimulated luminescence light, the amount of accumulated information decreases, so when the above-mentioned overlap of scanning lines occurs, the actual When performing a reading scan, the image information in the overlapping area has already been read and reduced by the excitation light irradiation during the previous retrace scan, making it difficult to read the image information accurately during the next scan. There was a problem that it was not done.

The present invention was made in view of the above circumstances, and
It is an object of the present invention to provide an image scanning reading device that can accurately read image information by eliminating the reduction in image information due to duplication of reciprocating main scanning lines.

The image scanning reading device of the present invention is provided with a focusing means for focusing the light beam at one point on the optical path of the scanning light beam, and synchronizes with the reciprocating main scanning at the focusing position of the light beam. The present invention is characterized in that a light shielding means is provided to prevent the passage of the light beam during the retrace scanning period.

As the focusing means of the present invention, for example, a pair of convex lenses can be used. Further, as the driving part of the light shielding means, in addition to a part that rotates and reciprocates, such as a galvanometer mirror, it may be a part that rotates or a part that reciprocates linearly. Any structure may be used as long as it can move the light blocking member synchronously and block the passage of the light beam during the retrace scanning period.

According to the image scanning reading device of the present invention, the light shielding means moves in synchronization with the reciprocating main scanning of the main scanning means of this device and prevents the passage of the light beam during the retrace scanning period, to the light beam focusing position. This prevents the irradiation of the light beam onto the stimulable phosphor sheet during retrace scanning, and prevents the amount of information accumulated on the stimulable phosphor sheet from being retrace scanned. Since the image information is not reduced, accurate reading of image information can be performed. In addition, since the light beam is blocked at a position where the beam diameter is small, the change in the light blocking member of the light blocking means required for blocking light may be slight, and the size of the light blocking member can be made small. can. Therefore, the rotational movement or reciprocating movement of the driving section of this light shielding means can be made high speed, and therefore it is possible to cope with high-speed reading scanning.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of an image scanning reading device according to the present invention. In FIG. 1, a magnetic layer 2a is laminated on the surface of an endless belt 2 which is drivably suspended around a pair of rollers 1a and 1b, and a phosphor sheet 3 is adhered to this layer by magnetic force to form an endless belt 2. It is driven by the rotation of rollers 1a and 1b (arrow A), and at the same time, a light beam 4 is emitted from above this phosphor sheet 3 from a laser light source 5 via a galvanometer mirror 6 in a direction perpendicular to the moving direction A of the endless belt 2 ( This shows an example in which the sheet 3 is two-dimensionally scanned with the light beam 4 by scanning in the direction of arrow B). That is, sub-scanning is performed in direction A by a sub-scanning means consisting of a pair of rollers 1a, 1b and an endless belt 2, and main scanning is performed in direction B perpendicular to the sub-scanning by a galvanometer mirror 6 as a main scanning means. . The endless belt 2 is made by laminating a magnetic layer 2a on a flexible endless belt-shaped support 2b.

Also, a laser light source 5 and a galvanometer mirror 6
There is a beam expander 9 on the optical path between the
A, 9b are provided, and at the beam focusing position of the beam expanders 9a, 9b, a rotary light shielding means 10 is arranged to block the laser beam during the retrace scanning period in synchronization with the reciprocating main scanning of the galvanometer mirror 6. ing.

Note that the purpose of expanding the beam diameter by the beam expanders 9a and 9b is to make the final imaging light spot smaller.
The laser beam whose beam diameter has been expanded by 9b is focused onto the phosphor sheet 3 by an imaging lens 11.

Further, the sheet 3 has a magnetic layer 3a and a stimulable phosphor layer 3b, and an image of radiation transmitted through the subject is stored and recorded in the stimulable phosphor layer 3b. When this sheet 3 is irradiated with a light beam 4, the irradiated portion exhibits stimulated luminescence, and this stimulated luminescence is focused by a total reflection light guide plate 7 made of, for example, an acrylic plate. The photodetector 8 is detected by a photoelectric detector 8 such as a photo sensor, and an image signal is obtained. The image signal is obtained as a time-series image signal according to two-dimensional scanning, and is used for image processing and reproduction.

FIG. 2 is an enlarged schematic diagram showing the rotating light shielding means 10 and beam expanders 9a, 9b shown in FIG.

The laser beam incident on the first lens 9a of the beam expander is focused once and then diverges to form the second lens.
The lens 9b converts the laser beam into a laser beam with an expanded beam diameter. At this beam focusing position, a rotating shaft is provided which is approximately parallel to the laser beam, and a rotating motor 1 is operated in synchronization with the reciprocating main scanning of the galvanometer mirror 6.
A sector 10a rotated by 0b is arranged. This sector 10a is made of a fan-shaped light shielding member, and is set at a timing and a circumferential angle so as to block the laser beam only during the retrace scanning period according to a synchronization signal from the galvanometer mirror 6.
According to this example, since the sector 10a is arranged at the beam focusing position, the sector 10a can be made small.Furthermore, since the sector 10a only needs to be rotated in one direction by the rotary motor 10b, it is easy to convert the sector 10a into a galvanometer. It is possible to cope with high-speed scanning of the mirror 6. It is more preferable to use a disc 10h as shown in FIG. 2A as the sector 10a so as not to generate wind during rotation. This disk 10
h is made of transparent glass or acrylic plate, etc., and a part thereof is coated with a light shielding member so as to block the laser beam during the retrace scanning period. In this example, light shielding parts and light transmitting parts are arranged on this disk 10h approximately every 90 degrees, and the light shielding parts block passage of the laser beam only during the retrace scanning period by a synchronization signal from the galvanometer mirror 6. It is set at such timing.

In this example, two sets of light-shielding parts and light-transmitting parts are arranged at 90° intervals, but the angle ratio of the light-shielding part and the light-transmitting part or the number of pairs of light-shielding parts and light-transmitting parts can be changed as necessary. may be increased or decreased.

FIG. 3A is a perspective view showing another example of the light shielding means of the image scanning reading device according to the present invention, and FIG. 3B is a schematic diagram showing the state in which the light shielding means is arranged on the optical path.

In this example, a light shielding member 10c is provided at the tip of a rotating shaft 10d of a galvanometer 10e, which is substantially perpendicular to the laser beam, and the light shielding member 10c is rotated back and forth by the galvanometer 10e. The light shielding member 10c is formed by forming a groove extending through the side surface of the upper surface of a cylindrical light shielding material, and is disposed at the beam focusing position in the beam expander as in the previous example. The galvanometer 10e rotates and reciprocates in synchronization with the reciprocating main scanning of the galvanometer mirror 6. That is, the light shielding member 10c is rotated and reciprocated so that the laser beam passes through the groove of the light shielding member 10c during the reading scan period, and so that both side walls of the groove block the laser beam during the retrace scanning period. According to this example, since the light shielding member 10c is disposed at the light convergence part, the light shielding member 10c can be formed small, and furthermore, the laser beam is blocked by both side walls of the groove part ( The laser beam can be blocked with a smaller rotation angle than when using one side wall.)
It is possible to cope with high-speed scanning of the galvanometer mirror 6.

FIG. 4 is a schematic diagram showing a third example of the light shielding means of the image scanning reading device according to the present invention.

In this example, a light shielding member 10f made of a plate-shaped metal is arranged approximately perpendicular to the laser beam at a beam focusing position in the beam expander, a solenoid 10g is provided below the light shielding member 10f, and a galvanometer is controlled by the solenoid 10g. mirror 6
The light shielding member 10f is moved up and down in synchronization with the reciprocating main scanning. That is, during the reading scan period, the light shielding member 10f is positioned below the laser beam to allow the laser beam to pass therethrough, and during the retrace scanning period, the light shielding member 10f is moved up and down so as to block the laser beam. According to this example, the light shielding member 10f is disposed at the light focusing portion, and the movable distance of the light shielding member 10f may be extremely small, so that it is possible to cope with high-speed scanning of the galvanometer mirror 6.

As explained in detail above, according to the present invention,
Since the irradiation of excitation light onto the stimulable phosphor sheet during retrace scanning is blocked by the light shielding means at the beam focusing position, the amount of information accumulated on the stimulable phosphor sheet is prevented during retrace scanning. so it is not diminished,
Accurate image information can be read out, and high-speed reading scanning can also be supported.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of an image scanning reading device according to the present invention, FIG. 2 is a schematic diagram showing an enlarged view of the beam expander section in FIG. 1, and FIG. FIG. 3A and FIG. 3B are perspective views and schematic diagrams showing another example of the light shielding means, and FIG. 4 is a schematic diagram showing still another example of the light shielding means. be. 2... endless belt, 3... stimulable phosphor sheet, 5... laser light source, 6... galvanometer mirror, 8... photoelectric detector, 9a, 9b... beam expander lens, 10... light shielding Means, 10a, 10c, 10f... Light shielding member, 10
b, 10e, 10g...drive unit, 10h...disc.

Claims (1)

[Scope of Claims] 1. An excitation light source, main scanning means for performing main scanning by reciprocally scanning a light beam emitted from the excitation light source onto a stimulable phosphor sheet on which image information is accumulated and recorded; A sub-scanning means that performs sub-scanning in a direction substantially perpendicular to the main-scanning direction, and scanning of the excitation light onto the stimulable phosphor sheet, produce stimulated luminescence light corresponding to image information emitted from the sheet. In an image scanning reading device having a reading means for photoelectrically reading, a focusing means for focusing the light beam at a point on the optical path of the light beam is provided, and the light beam focused by the focusing means is An image scanning/reading apparatus characterized in that a light shielding means is provided at a focusing position in synchronization with the reciprocating main scanning and for blocking passage of the light beam during the retrace scanning period of the main scanning. 2. The light shielding means is a sector having a rotation axis substantially parallel to the beam, rotating in synchronization with the reciprocating main scanning, and having a light shielding part that blocks passage of the beam during the retrace scanning period. An image scanning reading device according to claim 1, characterized in that: 3. The light shielding means has a rotating shaft substantially perpendicular to the beam, and a light shielding member made of a groove having a pair of opposing side walls is provided at the tip of the rotating shaft, and the light shielding member is used for the reciprocating main scanning. The galvanometer light shielding means is configured to rotate reciprocatingly in synchronization, and the beam is passed between both side walls of the groove part during the forward main scanning period, and the beam is passed between the both side walls of the groove part during the retrace scanning period. 2. The image scanning/reading device according to claim 1, wherein the image scanning/reading device is configured to prevent the beam from passing through. 4. The light shielding means is a piston-type light shielding means having a plate-shaped light shielding member that is provided substantially perpendicular to the beam and moves back and forth in synchronization with the reciprocating main scanning, and the light shielding means is a piston-type light shielding member that is provided substantially perpendicularly to the beam and has a plate-shaped light shielding member that moves back and forth in synchronization with the reciprocating main scanning, and the light shielding means 2. The image scanning reading device according to claim 1, wherein the member is arranged to prevent the beam from passing through.