JPS63276963A - Optical beam scanning reader - Google Patents

Abstract

PURPOSE:To enable advanced reading of a prescribed part of a face to be scanned by moving a 1st grid part at the main reading and a 2nd grid at the advanced read relatively to an optical beam so as to arrange them on the optical path of the branched light beam, respectively. CONSTITUTION:A synchronizing laser beam 2B reflected in a half mirror 6 is made incident on a grid 14 provided at a position conjugated with a storage fluorescent sheet 8 with respect to the mirror 6 while being prolonged in the main scanning direction. The grid 14 consists of a grid 14A for the main read and the grid 14B for the advanced read. A beam adjusting means 20 capable of going out and coming in with respect to an optical path of the laser beam 2 comprising an ND filter 17, a prism 18 and a concaved lens 18 is provided between a beam expander 3 and a rotary polygon mirror 4 and the means 20 is saved at the outside of the optical path at the main read, while being inserted in the optical path at the advanced read to adjust the laser beam. The luminous quantity change in the laser beam 2B is detected by a photodetector 16. Thus, the prescribed part of a face to be scanned is read in advance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a light beam scanning reading device for reading image information such as radiographic image information, and more particularly, the present invention relates to a light beam scanning reading device for reading image information such as radiation image information. The present invention relates to a light beam scanning/reading device capable of detecting the position of a light beam.

(Prior art) Conventionally, a light beam such as a laser beam is scanned two-dimensionally on a surface to be scanned on which image information is recorded, and the light beam is irradiated onto the surface to be scanned. Light beam scanning reading that reads image information recorded on the scanned surface by detecting light containing image information (e.g. reflected light, transmitted light, emitted light) using a light detection means equipped with a photomultiplier tube, etc. The device is widely used in practice.

Such light beam scanning and reading devices include plate-making scanners, computer and facsimile input devices. In addition to the above, radiation image information recording and reproducing systems using photostimulable phosphor sheets already proposed by the present applicant (Japanese Patent Laid-open Nos. 55-12429, 56-11395, 5
There is a radiation image information reading 5A position used in the 611397 bow, etc.).

In other words, when a certain type of phosphor is irradiated with radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.), a portion of this radiation energy is accumulated in the phosphor, causing the phosphor to It is known that when irradiated with excitation light such as visible light, phosphors exhibit stimulated luminescence depending on the accumulated energy.
Phosphors that exhibit these properties are called stimulable phosphors (stimulable phosphors). The above radiation image information reading device is
Using this stimulable phosphor, radiation image information of a subject such as a human body is recorded on a stimulable phosphor sheet, and this stimulable phosphor sheet is scanned with excitation light such as a laser beam to produce stimulated luminescence. It generates light and photoelectrically reads the resulting stimulated luminescent light to obtain an image signal. The excitation light is deflected by an optical deflector to main scan the stimulable phosphor sheet, and the excitation light and the stimulable phosphor sheet are relatively moved in a sub-scanning direction that is substantially orthogonal to the main scanning direction. By doing so, the entire surface of the stimulable phosphor sheet is scanned two-dimensionally.

Furthermore, in reading the radiation image information as described above, prior to the reading (main reading) to obtain the image signal for visible image output as described above, the outline of the radiation image information stored and recorded in the stimulable phosphor sheet in advance is read. There is a known method in which pre-reading is performed to read the image, reading conditions, etc. for performing the main reading are determined based on image information obtained by this pre-reading, and the main reading is performed according to the reading conditions.

As a method for performing such pre-reading, for example, a stimulable phosphor sheet is scanned using excitation light with an energy lower than that of the excitation light used for the above-mentioned main reading, and the stimulated luminescence light emitted by this scanning is also A reading method using a charging reading means (for example, Japanese Patent Application Laid-Open No. 58-6724
(see Publication No. 0), etc. In addition, the pre-reading described above is for reading the outline of radiation image information, and the pitch of the main scanning lines can be coarser than that for main reading, so the pitch of the main scanning lines can be coarsened to increase the processing speed and the pitch can be coarsened. During pre-reading, the beam diameter of the excitation light is made larger than during actual reading, so that the entire surface of the sheet can be scanned evenly even when the sheet is scanned evenly.

By the way, in a light beam scanning reading device, each time the reference amount changes in the scanning position fl/main scanning direction of the light beam, the output of the photodetector is integrated for a certain period of time within the period to read the image signal. It is necessary to obtain a synchronization signal that is synchronized with the scanning of the light beam. One of the methods commonly used in the past to obtain such a synchronization signal is to use an optical system to split the light beam directed toward the surface to be scanned and take out a part of it, and also to split the light beam toward the surface to be scanned by alternating bright and dark areas. A grid arranged in rows is arranged extending in the main scanning direction on the optical path of the extracted light beam, and changes in the amount of light of the light passing through (transmitted or reflected) the grid are converted into electrical pulse signals. A known method is to obtain a synchronization signal by inputting the light into a synchronization signal generating means and detecting periodic changes in the amount of light passing through the grid through the above scanning. By obtaining a synchronization signal that indicates the scanning position of the light beam in this way, it is possible to perform highly accurate reading, and it is also possible to detect the position of the light beam on the surface to be scanned. It is also possible to actually start reading from the beginning and read only a part of the surface to be scanned.

(Problem to be Solved by the Invention) In the above-mentioned grid, the pitch and width of the grating (bright area) through which the light beam passes are determined depending on the beam diameter of the light beam for scanning, so that the beam spot can pass through the grating. It is decided to pass one by one. Therefore, when performing pre-reading as described above, the beam diameter of the light beam is expanded compared to that during main reading, so even if the light beam is incident on a grid designed to match the beam diameter of the light beam during main reading, the light beam will not be visible. The beam is incident across multiple gratings at once, making it impossible to create a synchronized signal.

For this reason, the scanning position cannot be detected during pre-reading, and pre-reading must always be carried out over the entire surface to be scanned. Therefore, as mentioned above, when it is desired to perform main reading on only a part of the surface to be scanned, it is necessary to This causes the inconvenience of not being able to read ahead.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a light beam scanning reading device that can obtain a synchronization signal even during pre-reading and can also perform pre-reading of only a part of the surface to be scanned. The purpose is to

(Means for Solving the Problems) The light beam scanning reading device of the present invention branches the light beam directed toward the surface to be scanned, takes out a part of it, and places the light beam on the optical path of the taken out light beam in the main scanning direction. A grid extending in the direction of the main beam is provided, a light beam is made incident on the grid to detect the position of the light beam on the surface to be scanned, and the grid has a pitch and width suitable for the beam diameter of the light beam at the time of main reading. and a second grid section having a grating having a pitch and width suitable for the beam diameter of the light beam at the time of read-ahead, and the first grid part has a grating having a pitch and a width suitable for the beam diameter of the light beam at the time of the read-ahead. The present invention is characterized in that the two grid sections are moved relative to the light beam so that they are arranged on the optical paths of the branched light beams.

Note that here, when we say that we have a grating with a pitch and width appropriate for the beam diameter, we mean that the grid has a grating (bright part) so that each light beam passes through it one by one according to the beam diameter. It means something.

Further, the first grid section and the second grid section may be integrated or separate, and in either case, the above-mentioned grid is constituted by both grid sections.

(Function) According to the light beam scanning reading device as described above, a grid having a grid section for pre-reading and a grid section for main reading is provided, and by moving both grid sections in and out relative to the light beam, the main reading can be performed. In addition, it becomes possible to create a synchronizing signal even in advance, and it becomes possible to perform advance reading only on a predetermined portion of the surface to be scanned.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a radiation image information reading device which is an embodiment of the light beam scanning scanning method of the present invention.

Laser light 2, which is excitation light emitted from laser light source 1, enters beam expander 3 and is adjusted to a predetermined beam diameter, and then is reflected and deflected by rotating polygon 14 rotating in six directions of arrows. After the reflected and deflected laser beam 2 passes through a scanning lens 5 such as an fθ lens, a half mirror 6 provided on the optical path converts it into a scanning laser beam 2A, which is transmitted light, and a synchronization laser beam 2B, which is reflected light. be divided. The scanning laser beam 2A repeatedly scans the stimulable phosphor sheet 8 in the A' force direction on the stimulable phosphor sheet 8 on which radiographic image information is accumulated and recorded and is conveyed (sub-scanned) in the direction of the arrow B by the conveying means 7.

That is, since the sheet 8 is conveyed in a direction substantially perpendicular to the main scanning direction of the scanning laser beam 2A, the rotation polygon 114 deflects the scanning laser 2 and the conveyance means 7 conveys the stimulable phosphor sheet 8. As a result, two-dimensional scanning is performed over the entire surface of the stimulable phosphor sheet 8 by the scanning laser beam 2A.

As the scanning laser beam 2A scans, the area of the stimulable phosphor sheet that is irradiated with the scanning laser beam 2A emits stimulated light according to the image information accumulated there, and this emitted light is The light enters a transparent light guide having an incident end surface 9a formed parallel to the main scanning line in the vicinity of the fluorescent phosphor sheet from the incident end surface 9a. The light guide 9 has a flat front end 9b located near the stimulable phosphor sheet 8, and gradually becomes cylindrical toward the rear end, and has a substantially cylindrical shape at the rear end 9C. Since the photomultiplier tube 10 is connected to the photomultiplier tube 10 provided on the exit end surface, the stimulated emitted light entering from the entrance end surface 9a is collected at the rear end portion 9C and is stimulated. The emitted light is transmitted to the photomultiplier 10 via a filter (not shown) that selectively transmits the emitted light. Further, at a position facing the incident end surface 9a of the light guide 9 across the main scanning line, a reflecting mirror 24 is provided which extends in the main scanning direction and reflects the incident stimulated luminescence light toward the incident end surface 9a. It is being

In the photomultiplier 10, the stimulated luminescent light is converted into an electrical signal, and the obtained electrical signal is sent to an image information reading circuit 11 for processing, and then outputted as a visible image to, for example, a CRT 12. , recorded on the magnetic tape 13, or directly recorded as a hard copy on a photosensitive material or the like.

On the other hand, the synchronizing laser beam 2B reflected by the half mirror 6 enters a grid 14 extending in the main scanning direction and provided at a position conjugate with the stimulable phosphor sheet 8 with respect to the half mirror 6. This grid 14 has a grating pitch and width that are determined by the synchronizing laser beam 2 during image reading (main reading).
A first grid portion 14A suitable for the beam diameter of B;
A second grid section 1 which is arranged below the grid section and has a larger grid pitch and width than the first grid section.
4B, and during main reading, the synchronizing laser beam 2B is incident on the first grid section 148. The synchronizing laser beam 2B that has passed through this first grid 14A is transmitted to the grid portion 1
The light is focused by a focusing bar 15 provided behind 4A,
The focused synchronizing laser beam 2B is detected by photodetectors 16 provided at both ends of the focusing bar 15. The amount of light detected by this photodetector 16 is
The lattice changes periodically with the main scanning of the scanning laser beam 2A. Light detection! 116 detects periodic changes in the synchronizing laser beam 2B, and this light intensity change is converted into an electrical pulse signal by a synchronizing signal generating means (not shown), and the position of the scanning laser beam 2A in the main scanning direction is A synchronization signal indicating this is obtained. Note that the first grid section 14
The means for detecting the light passing through A is not limited to the one consisting of a condensing bar and a photodetector as described above. There may be one such as provided behind the grid section. Furthermore, the grid portion 14A may be one that periodically changes the reflection state of the synchronization laser beam, and in that case, the photodetector may detect the light reflected by the grid portion.

By the way, in this device, prior to the book reading mentioned above,
Pre-reading is performed to roughly read the image information stored and recorded on the stimulable phosphor sheet 8. When performing this pre-reading, the intensity of the laser beam 2 is reduced, the beam diameter at the scanning position is enlarged, and the optical path is slightly moved compared to the actual reading. That is, between the beam expander 3 and the rotating polygon &1!4, there is an ND filter 17 for reducing the intensity.
A beam adjusting means 20 is provided which can move in and out of the optical path of the laser beam 2, which includes a prism 18 for minutely moving the optical path, and a concave lens 19 for expanding the beam diameter. Although it is retreated out of the optical path, it is inserted into the optical path during pre-reading and performs the above-mentioned adjustment to the laser beam. Figure 2(a) shows the optical path and beam diameter of the laser beam 2 during book reading, and Figure 2(b)
) show the optical path and beam diameter of the laser beam 2' during pre-reading, respectively.

The reason for changing the optical path of the laser beam during pre-reading is to increase the focusing efficiency of stimulated luminescence light during main reading, as shown in FIG.
This is to prevent the end of the light guide 9 from being irradiated with laser light when the beam diameter is expanded during pre-reading since the light guide 9 is disposed extremely close to the main scanning line. Therefore, the optical path of the laser beam 2' is changed in the direction in which the scanning laser beam 2A' passing through the half mirror 6 is separated from the light guide 9. Along with this, the reflection mirror 24 is also changed as shown in FIG.
As shown in b), the light guide 9 moves in the direction of arrow C to widen the distance between the light guide 9 and the incident end surface 9a.

As described above, during pre-reading, the laser beam 2' is reduced in intensity, enlarged in beam diameter, and expanded in optical path by the beam adjustment means 20. Through this adjustment, the stimulable phosphor sheet 8 The state of the synchronizing laser beam 2B' reflected by the half mirror 6 also changes on the grid 14 which is in a conjugate relationship with . That is, as shown in FIG. 2(b), the synchronizing laser beam 2B'
is compared to the synchronizing laser beam 2B during main reading.
4, the beam diameter increases and the optical path moves downward. Therefore, when reading ahead, the synchronization laser beam 2
B' enters the second grid portion 14B provided below the first grid 14A. Grid 14a of first and second grid portions 14A, 14B.

14b pitch and width and synchronization laser beams 2B, 2B'
The relationship between the beam diameters is as shown in FIG.
This is suitable for the beam diameter of the synchronizing laser beam 2[3' during look-ahead reading, which is larger than the pitch and width of . Therefore, during pre-reading as well as during main reading, the synchronizing laser beam 2B' moves in the direction of the arrow while reaching the second grid section 14.
The synchronizing laser beams 2[
The photodetector 16 described above detects the change in the light m at 3', thereby making it possible to obtain synchronization reliability. Therefore, based on the obtained synchronization signal, the scanning position of the scanning laser beam 2A' can be detected even during pre-reading, and it is also possible to pre-read only a part of the stimulable phosphor sheet 8 if necessary. becomes.

In the above embodiment, the optical path of the scanning laser beam is changed between pre-reading and main reading, and the synchronizing laser beam whose optical path changes accordingly is incident on the first and second grids as appropriate. However, if there is no need to change the optical path of the scanning laser beam between pre-reading and main reading, rotate the half mirror 6 in the direction of the arrow as shown in Figure 4. 2. It is reflected light when reading a book.
Only the optical paths of the two synchronizing laser beams 2B and 28' may be changed. In addition, the optical path of the synchronizing laser beam is kept constant, and the grid 14 is moved up and down, so that the first grid 8I is moved up and down during main reading.
114A and the second grid portion 14B may be arranged on the optical path of the synchronizing laser beam at the time of pre-reading. Furthermore, the first grid section 14A and the second grid section 14B may be arranged in series in the width direction (main scanning direction), and the grid sections may be switched by moving the grid in the width direction,
Both grids may be made separate from each other and used in conjunction with each other as appropriate. Further, the light detection means such as the light condensing bar and the photodetector described above may be provided one each for main reading and pre-reading.

The apparatus of the present invention has been explained above by taking a radiation image information reading apparatus using a stimulable phosphor sheet as an example, but the apparatus of the present invention is a light beam scanning reading apparatus that performs pre-reading other than the above-mentioned radiation image information reading apparatus. The same effects as those described above can also be achieved in devices other than the above-mentioned embodiments.

(Effects of the Invention) As described above in detail, according to the optical beam scanning reading device of the present invention, the grid has a first grid section for main reading and a second grid section for pre-reading, By selectively injecting the synchronizing laser beam into these grid portions during main reading and during pre-reading, a synchronizing signal can be obtained even during pre-reading in which the beam diameter of the laser beam is expanded. Therefore, if you want to read image information from only a part of the scanned surface, it is possible to detect the scanning position of the light beam during pre-reading and pre-read only the predetermined part, which is efficient and reliable. It becomes possible to read ahead.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a radiation image information reading device which is an embodiment of the optical beam scanning reading device of the present invention, and FIG. 2(a)
, (b) is a schematic side view showing the state of the laser beam during main reading and pre-reading in the above device A3, FIG. 3 is a schematic front view showing the grid lattice and beam diameter, and FIG. 2.2'...Laser beams 2A, 2A'...Scanning laser beams 2B, 2B'...Synchronization laser beams 4...Rotating polygon mirror 5...Scanning lens 6...
・Half mirror 8...Stormable phosphor sheet 14...Grid 14Δ...First grid section 14B...Second grid section 14a, 14b -...Grid FIG.

Claims (1)

[Claims] A light beam is deflected in the main scanning direction by an optical deflector to two-dimensionally scan a scanned surface that carries image information and is moved in the sub-scanning direction relative to the light beam. In the optical beam scanning reading device, the optical beam scanning reading device performs main reading for visible image reproduction, and also performs pre-reading to read an outline of the image information using a light beam whose beam diameter is enlarged from that at the time of main reading, prior to the main reading. A light beam directed toward the surface to be scanned is branched and a part thereof is extracted, a grid extending in the main scanning direction is provided on the optical path of the extracted light beam, and the light beam is made incident on the grid to form a part of the light beam on the surface to be scanned. detecting the position of the light beam at the time of reading, the grid having a grid having a pitch and width suitable for the beam diameter of the light beam at the time of main reading; a second grid portion having a grid of pitch and width;
A light beam characterized in that the first grid portion is moved relative to the light beam during main reading, and the second grid portion is moved relative to the light beam during pre-reading so that they are respectively arranged on the optical path of the branched light beam. Scanning reading device.