JPH04367815A - Light beam scanning device - Google Patents

Abstract

PURPOSE:To scan a large-sized body with a light beam although the scanning angle of the light beam is small by arranging plural scanning lines of different positions on the scanned body in a main scanning direction. CONSTITUTION:Light beams La and Lb which are reflected by a polygon mirror 14 and deflected in the main scanning direction are put on one over the other before being made incident on separating reflecting mirrors 18 and 20, but separated vertically in a subscanning direction. The light beams La and Lb which are reflected by the separating reflecting mirrors 18 and 20 are made incident on corresponding falling mirrors 22 and 24 as optical path adjusting means and reflected to the scanned body A, which is irradiated. The falling mirrors 22 and 24 are so arranged that the scanning lines Sa and Sb which are formed by the light beams La and Lb are put in array in the main scanning direction to form a main scanning line and also become equal in optical path length. Consequently, the scanning angle of the polygon mirror is small and the optical path length up to the scanned body can be shortened.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam scanning device applied to image reading devices, image recording devices, etc. Specifically, the present invention relates to a light beam scanning device that is small in size yet capable of scanning a large-sized object with a light beam.

0002

[Prior Art] Certain types of phosphors are exposed to radiation (X-rays, α-rays,
When the phosphor is irradiated with β-rays, γ-rays, electron beams, ultraviolet rays, etc., it accumulates some of this radiation energy, and then when this phosphor is irradiated with excitation light such as visible light, the accumulated energy is It is known that it exhibits stimulated luminescence depending on the
A phosphor exhibiting such properties is called a stimulable phosphor (stimulable phosphor).

By using this stimulable phosphor, radiation image information of objects such as human bodies and buildings can be stored on a sheet having a layer of stimulable phosphor (hereinafter referred to as stimulable phosphor sheet).
This phosphor sheet is scanned two-dimensionally with excitation light such as a laser beam to generate stimulated luminescent light, and this stimulated luminescent light is read photoelectrically to generate an image signal. The present applicant has proposed a radiation image information recording and reproducing system that outputs the radiation image of the subject as a visible image to a recording material such as a photographic light-sensitive material or a display device such as a CRT based on this image signal ( Japanese Patent Publication No. 55-12429
No. 56-11395, etc.).

Similar to radiographs such as X-rays, such radiographic image information recording and reproducing systems are used not only for medical purposes such as medical diagnosis and inspection, but also in recent years for non-destructive inspection of buildings, aircraft, etc. It is also suitably applied to industrial applications.

In such a radiation image information recording and reproducing system, image recording on the phosphor sheet is performed by irradiating the phosphor sheet with radiation that has passed through an object such as a human body or a building. On the other hand, reading of the radiation image information stored and recorded on the phosphor sheet in this manner is carried out in the following manner by a radiation image information reading device applying a so-called light beam scanning device.

A light beam scanning device two-dimensionally scans a scanned object that moves relatively in a sub-scanning direction substantially orthogonal to the main-scanning direction using a light beam deflected in a main-scanning direction. This is a device that irradiates (scans) the entire surface of a scanned object with the light beam. For example, when reading a phosphor sheet in the above-mentioned radiation image information reading device, the light beam scanning device transports the phosphor sheet carrying radiation image information in the sub-scanning direction while excitation is deflected in the main-scanning direction. This is done by scanning this phosphor sheet with light (light beam).

Specifically, excitation light of a constant intensity emitted from an excitation light source such as a He-Ne laser is reflected and deflected in the main scanning direction by an optical deflector such as a galvanometer mirror, and is reflected and deflected in the main scanning direction by an optical deflector such as a galvanometer mirror. The phosphor sheet is irradiated through the optical element.

[0008] Here, the phosphor sheet is conveyed on a belt conveyor,
It is transported in a sub-scanning direction that is substantially orthogonal to the main scanning direction by a transporting device such as a nip roller. Therefore, the excitation light deflected in the main scanning direction can two-dimensionally scan the entire surface of this phosphor sheet.

[0009] Stimulated luminescence light corresponding to the radiographic image information accumulated and recorded there is generated from the part of the phosphor sheet that is irradiated with the excitation light. This stimulated luminescence light is directly incident on the incident surface of the light guide, or is reflected by a condensing mirror disposed opposite to this incident surface, enters the incident surface of the light guide, is transmitted by the light guide, and is excited. After passing through a filter that cuts light in the wavelength range, it enters a photomultiplier tube, where it is photoelectrically converted into an electrical signal, processed, and reproduced as a visible image on a CRT or photosensitive material, or as a visible image on a CRT or photosensitive material. Recorded and stored on a recording medium.

[0010] Such a light beam scanning device is suitable not only for the above-mentioned radiation image information reading device but also for image recording devices such as laser beam printers, copying machines, printing plate making devices, and image reading devices such as film digitizers. applied to.

[0011]

However, when scanning a large object to be scanned using such a light beam scanning device, it is necessary to increase the size of the device in accordance with the size of the object to be scanned.

As described above, the light beam scanning device scans an object to be scanned, which moves relatively in the sub-scanning direction, with a light beam deflected in the main scanning direction, which is substantially perpendicular to the sub-scanning direction. Therefore, in order to scan the entire surface of a large object, the scanning length of the light beam (in the main scanning direction) is required to be greater than the width of the object in the main scanning direction. In order to achieve this, it is necessary to ensure a sufficient main scanning length by increasing the focal length of the light beam optical system and increasing the scanning angle of the light beam by the optical deflector.

[0013] Therefore, the optical path length of the light beam becomes longer,
Moreover, the optical device of the light beam scanning device also becomes large, and the light beam scanning device becomes extremely large, with a long distance from the optical deflector to the object to be scanned, and a large dead space.

In particular, when the above-mentioned radiation image information recording and reproducing system is applied to industrial applications such as non-destructive inspection of buildings and aircraft, large phosphor sheets are often used, and accordingly, radiation Since the image information reading device also increases in size, improvements are required.

An object of the present invention is to solve the problems of the prior art described above, and despite the fact that the device size is small and the scanning angle of the light beam is small, it is possible to use a large-sized industrial phosphor sheath. An object of the present invention is to provide a light beam scanning device capable of scanning the entire surface of a scanned object with a light beam.

[0016]

Means for Solving the Problems In order to achieve the above object, the present invention provides a method for moving a scanned object relatively in a sub-scanning direction substantially perpendicular to the main-scanning direction by a light beam deflected in the main-scanning direction. A light beam scanning device for two-dimensionally scanning a body, the light beam being reflected by a rotating polygon mirror periodically having a plurality of types of reflective surfaces that differ in the sub-scanning direction; a separation reflection mirror that reflects the light beam so as to separate it at least in a direction perpendicular to the sub-scanning direction for each reflection angle in the sub-scanning direction;
A main scanning line is formed on the object to be scanned by combining a plurality of scanning lines, each of which has an equal optical path length, and which is formed by each of the light beams reflected by the separation reflection mirror. There is provided a light beam scanning device characterized in that it has a light path adjusting means for making the light beam incident on the object to be scanned.

[0017]

Effect of the Invention The light beam scanning device of the present invention uses a light beam deflected in the main scanning direction by a rotating polygon mirror to detect a target that moves relatively in the sub-scanning direction substantially orthogonal to the main scanning direction. A light beam scanning device that scans a scanning object two-dimensionally, using a rotating polygon mirror that periodically has a plurality of types of reflective surfaces with different reflection angles in the sub-scanning direction, and using this rotating polygon mirror to scan a scanning object in the sub-scanning direction. scan line formed by multiple light beams reflected at different angles,
By connecting in the main scanning direction, main scanning lines are formed on the object to be scanned.

In a conventional light beam scanning device, a main scanning line is formed by a light beam reflected by one reflecting surface of a polygon mirror, that is, one scan by the polygon mirror. Therefore, in order to apply large objects such as industrial phosphor sheets as objects to be scanned, the focal length of the light beam optical system must be increased, and the scanning angle of the light beam by the optical deflector must be increased. As described above, it is necessary to increase the main scanning length, and the optical beam scanning device becomes a large device with a long distance from the optical deflector to the object to be scanned and a large dead space.

On the other hand, the light beam scanning device of the present invention uses a predetermined polygon mirror as described above and connects a plurality of scanning lines to form a main scanning line on the object to be scanned.

In the light beam scanning device of the present invention, the light beam incident on the polygon mirror is reflected at different angles in the sub-scanning direction depending on the reflecting surface of the polygon mirror. In other words, if the polygon mirror periodically has reflecting surfaces at three different angles, the three types of polarized light beams will be
If it has periodically reflecting surfaces at different angles, two types of polarized light beams are periodically formed.

At this point, these deflected light beams overlap in the sub-scanning direction, but then they are incident on their corresponding separation reflection mirrors and are deflected at least in the direction perpendicular to the sub-scanning direction. For example, if there are three types of polarized light beams, there will be two beams in the center and on the left and right.
If it is a kind of polarized light beam, it will be reflected so as to be divided into left and right sides. The optical path of each deflected light beam is then adjusted by an optical path adjusting means such as a mirror, and the beam enters the object to be scanned to form a scanning line.

In the light beam scanning device of the present invention, the optical path adjustment means is arranged so that the optical path length of each light beam is equal and each scanning line is incident in a line in the main scanning direction. be done. In other words, in the light beam scanning device of the present invention, a plurality of scanning lines reflected at different angles in the sub-scanning direction by the polygon mirror, for example, as described above, the polygon mirror has three reflecting surfaces at different angles periodically. If it is formed, 3 formed by it
If the seed scanning line is one in which reflective surfaces of two different angles are periodically formed, the two types of scanning lines formed thereby can be arranged in a line in the main scanning direction to scan the object to be scanned. A main scanning line is formed above.

Therefore, even if the scanning angle of the polygon mirror is small and the optical path length to the object to be scanned is shorter than that of the polygon mirror, the main scanning line on the object to be scanned can be made long, and even if the scanning object is large, the main scanning line can be made long. Even a light beam scanning device that scans the body can be made compact with significantly reduced dead space. Therefore, by applying the light beam scanning device of the present invention, it is possible to significantly downsize radiation image information reading devices for industrial use such as non-destructive inspection of buildings, which use large phosphor sheets. can do.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The light beam scanning device of the present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings.

FIG. 1 shows a schematic perspective view of an example of a light beam scanning device according to the present invention.

The light beam scanning device 10 shown in FIG.
The light beam L is deflected in the main scanning direction (arrow a direction) to two-dimensionally scan the entire surface of the scanned object A being conveyed in the sub-scanning direction (arrow b direction) substantially orthogonal to the main scanning direction. By doing so, image information is read from a stimulable phosphor sheet or the like, or image recording is performed on a recording material or the like.

Such a light beam scanning device 10 includes a light source 12 of a light beam L and a polygon mirror (rotating polygon mirror) 1.
4, the fθ lens 16, and the separate reflection mirrors 18 and 2.
0 and downward mirrors 22 and 24. In addition, in the light beam scanning device 10 of the present invention, in addition to these optical elements, various optical elements applied to a normal light beam scanning device, such as a surface tilt correction optical system and an acousto-optic modulator, are included. Of course, it may be deployed as needed.

The light beam L is emitted from the light source 12 and enters the polygon mirror 14 . The light source 12 may be appropriately set depending on the object A to be scanned, and various light sources such as a He-Ne laser and a semiconductor laser can be used.

The polygon mirror 14 rotates in the direction of arrow c to direct the light beam L in the main scanning direction (direction of arrow a).
It is reflected and deflected. Here, this polygon mirror 14 is one of the characteristic members of the present invention.

FIG. 2 shows a schematic perspective view of the polygon mirror 14.

The polygon mirror applied to the light beam scanning device of the present invention has a configuration in which a plurality of types of reflecting surfaces having different reflection angles in the sub-scanning direction are arranged periodically, and the polygon mirror shown in the figure The mirror 14 has a total of six reflective surfaces, and directs the light beam L forward in the sub-scanning direction (hereinafter referred to as "upward").
an upper reflective surface 14a that reflects the light beam L backward in the sub-scanning direction (hereinafter referred to as "downward")
b are arranged alternately. In other words, the illustrated polygon mirror 14 has a configuration in which two types of reflective surfaces having different reflection angles are periodically arranged three times.

The light beam L incident on such a polygon mirror 14 is incident on and deflected by the upper reflective surface 14a, and is transformed into a (deflected) light beam La that travels upward, and the lower reflective surface 1.
4b and is deflected into a (deflected) light beam Lb that travels downward.

The polygon mirror is not limited to the illustrated example, but may be one in which three or more types of reflecting surfaces having different reflection angles are periodically formed. Further, the total number of reflective surfaces is not limited to six, and may have eight or more reflective surfaces in total. However, in the light beam scanning device of the present invention, the total number of reflective surfaces of the polygon mirror is a multiple of the types of reflective surfaces.

The light beams La and Lb reflected by the polygon mirror 14 and deflected in the main scanning direction have their focal positions adjusted by the fθ lens 16, and then the light beams La and Lb are reflected by the polygon mirror 14.
The light beam La incident on the upper reflective surface 14a and reflected
The light beam Lb travels upward, enters the separation reflection mirror 18 and is directed to the right in the figure, while the light beam Lb that enters the lower reflection surface 14b and is reflected downward enters the separation reflection mirror 20 disposed below. The light is incident and reflected toward the left in the figure, approximately in the main scanning direction. In other words, the light beams La and Lb reflected by the polygon mirror 14 and deflected in the main scanning direction are in a vertically overlapping state until they enter the separation reflection mirrors 18 and 20. , are separated at least in the direction perpendicular to the sub-scanning direction (in the surface direction of the scanned object A).

There are no particular limitations on the separation reflection mirrors 18 and 20, and any mirrors that are used in ordinary light beam scanning devices can be used. Further, the direction of reflection of each light beam is not limited to the substantially main scanning shown in the illustrated example, but may be sufficient as long as it is possible to separate the vertically overlapping light beams La and Lb at least in the direction perpendicular to the sub-scanning direction. .

The light beams La and Lb reflected by the separation reflection mirrors 18 and 20 then enter the corresponding downward mirrors 22 and 24, which are optical path adjusting means, and are reflected toward the object A to be scanned. and irradiates the object to be scanned.

In the light beam scanning device 10 of the present invention, the falling mirrors 22 and 24 scan lines Sa and S formed by the light beams La and Lb.
b are lined up in a line in the main scanning direction to form a main scanning line S,
The light beams La and Lb are arranged so that the optical path lengths thereof are equal.

FIG. 3 conceptually shows a plan view of the light beam scanning device 10.

As shown in FIG. 3(a), the light beam La that is incident on the upper reflecting surface 14a of the polygon mirror 14, reflected and deflected, is incident on the separation reflecting mirror 18, and is reflected and deflected in the direction substantially in the main scanning direction. The light is reflected in the middle right direction, and is further reflected by the falling mirror 22, and scans the scanned object A from the right to the left in the figure, forming a scanning line Sa that is the right half of the main scanning line S.

On the other hand, the lower reflecting surface 1 of the polygon mirror 14
The light beam Lb that is incident on the light beam 4b and reflected and deflected travels below the light beam La and enters the separation reflection mirror 20 as shown in FIG. It is reflected to the left, further reflected by the falling mirror 24, and scans the scanned object A from the right to the left in the figure, forming a scanning line Sb which is the left half of the main scanning line S. A main scanning line S is formed together with the scanning line Sa.

Here, the object to be scanned A is sub-scanned and conveyed in a sub-scanning direction (direction of arrow b) substantially perpendicular to the main-scanning direction by a sub-scanning conveying means (not shown). Therefore, the scanned object A is two-dimensionally covered over its entire surface by the light beams La and Lb that are deflected in the main scanning direction. The entire surface is scanned by the scanning line S.

According to the light beam scanning device of the present invention having such a configuration, the main scanning line is formed by arranging a plurality of scanning lines formed by the polygon mirror in the main scanning direction, so that the light beam by the polygon mirror is Even if it is a small optical beam scanning device with a small beam scanning angle and a short dead space from the polygon mirror to the scanned object A, it is difficult to use a stimulable phosphor sheet for industrial use. The present invention can be suitably applied to a radiation image information reading device that uses a large-sized object to be scanned, an image recording device that uses a large-sized recording material, and the like.

There is no particular limitation on the sub-scanning conveyance means for the object A to be scanned, and a pair of nip rollers disposed with the main scanning line S in between, a belt conveyor, etc. may be used in a sheet-like manner applicable to known light beam scanning devices. Any means of conveying objects is applicable. Alternatively, the sub-scanning may be performed by fixing the object to be scanned and moving the main scanning means.

In the illustrated example of the light beam scanning device 10, the optical path adjusting means is performed by one mirror of the falling mirrors 22 and 24 corresponding to the light beams La and Lb, respectively, but other mirrors may be used as necessary. Optical elements such as mirrors and lenses may be provided so that each light beam enters the object A to be scanned so as to be connected in the main scanning direction with the same optical path length.

The illustrated light beam scanning device 10 uses a polygon mirror 14 having two types of reflection angles, an upper reflection surface 14a and a lower reflection surface 14b, and connects two scanning lines to form a main scanning line. However, the present invention is not limited to this, and uses a polygon mirror having three or more types of reflection angles,
A main scanning line may be formed by connecting three, four, or more scanning lines.

For example, in the case of a light beam scanning device that uses polygon mirrors having three types of reflection angles to form a main scanning line with three scanning lines, the direction of reflection of each deflected light beam by the separate reflection mirror is , the above-mentioned left and right direction, and the direction opposite to the direction in which the light beam travels up to that point (center direction)
The overlapping polarized light beams in the vertical (sub-scanning) direction are separated, and each deflected light beam is directed to the scanned object A with the same optical path length.
An optical path adjusting means such as a mirror may be arranged so that the scanning lines defined by the respective deflected light beams are aligned in the main scanning direction.

In this case, care must be taken because the scanning directions of the polarized light beam reflected in the left-right direction and the polarized light beam reflected in the central direction are opposite to each other.

[0048] Such a light beam scanning device of the present invention has the following features:
It is suitably applicable to various image recording devices, image reading devices, etc., such as various printers and copying machines, as well as radiation image information reading devices that apply stimulable phosphor sheets. In particular, the present invention is suitably applied to image reading devices and image recording devices that use large objects to be scanned, such as large stimulable phosphor sheets used in non-destructive inspection of buildings.

[0049]

Effects of the Invention As described in detail above, the light beam scanning device of the present invention has a small scanning angle of a polygon mirror, even if it is a device with a long main scanning line for scanning a large object to be scanned. The optical path length to the object to be scanned is shorter than that of the polygon mirror, and a compact device with significantly reduced dead space can be achieved. Therefore, by applying the light beam scanning device of the present invention, it is possible to significantly downsize radiation image information reading devices for industrial use such as non-destructive inspection of buildings, which use large phosphor sheets. be able to.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing an example of a light beam scanning device of the present invention.

2 is a schematic perspective view of a polygon mirror applied to the light beam scanning device shown in FIG. 1. FIG.

FIG. 3 is a diagram conceptually showing a plan view of the light beam scanning device shown in FIG. 1;

[Explanation of symbols]

10 Light beam scanning device 12 Light source 14 Polygon mirror 16 fθ lens 18, 20 Separate reflection mirror 22, 24 Hanging mirror A Scanned object L, La, Lb light beam S Main scanning line Sa, Sb scanning line

Claims (1)

[Claims] 1. A light beam scanning device that two-dimensionally scans a scanned object moving relatively in a sub-scanning direction substantially orthogonal to the main-scanning direction with a light beam deflected in the main-scanning direction, comprising: a rotating polygon mirror periodically having a plurality of types of reflecting surfaces with different reflection angles of light beams in the sub-scanning direction; A separate reflection mirror that reflects the light beams so as to be divided in a direction perpendicular to the sub-scanning direction, and a light beam that is formed by each light beam, the light beams having the same optical path length and reflecting the light beams reflected by the separation reflection mirror. 1. A light beam scanning device comprising: an optical path adjusting means for making a plurality of scanning lines incident on the object to be scanned so as to combine a plurality of scanning lines to form a main scanning line on the object to be scanned.