JPS5939162A - Latent image readout device - Google Patents

Abstract

PURPOSE:To save a reading time, by changing the scanning angle in main and sub-scanning direction of a light beam so as to change the range of reading of an object picture. CONSTITUTION:A light beam L is made incident to a rotary polygon mirror 16 and the image is formed on the picture storage board in the size of the entire screen, by saving an optical path switching reflecting mirror 18 from the optical path and irradiating the light beam L to obtain a large picture covering the entire screen. To obtain a picture with a small picture angle, the optical path switching reflecting mirror 18 is inserted in the optical path and the light beam L is deflected in the direction of a galvano mirror 17, allowing to reduce the picture angle in the main and the sub-scanning direction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a latent image reading device that reads an image by optically scanning a laser beam or the like from an image storage plate storing images as latent images.

2. Description of the Related Art As a means for reading image signals two-dimensionally accumulated as a latent image on an image storage plate, there is a method that scans a laser beam or the like and irradiates the image storage plate. For example, in an electrostatic image storage plate, the resistance of the photoconductor layer in the area hit by the scanning laser beam decreases, and the accumulated image signals are transmitted in a time-series manner.
By processing this signal, it is possible to observe the image on a CRT, to make a hard copy onto a film or the like, to file it to a magnetic memory or the like, or to transmit the image.

Specifically, as shown in FIG. 1, for example, a subject 2 is located in front of a housing 1, an illumination light source 3 is provided diagonally above the subject 2, and an imaging optical system is installed inside the housing 1 from the front. A system 4, a shutter 5, and an image storage board 6 are installed, and a laser light source 7 is placed behind them. be guided.

In this state, the subject 2 illuminated by the illumination light source 3 with the shutter 5 open forms an image on the image storage plate 6 by the imaging optical system 4, forming an electrostatic latent image. Thereafter, the shutter 5 is closed, and when the laser light source 7 emits the light beam L, the light beam L passes through the scanning optical system 8 and optically scans the image storage plate 6 two-dimensionally. In this case, front exposure is required as pre-processing of the image storage plate 6 before imaging.

FIG. 2 is an explanatory diagram for the case of obtaining an X-ray transmission image, in which the subject 2 is placed between the X-ray tube 9 and the image storage board 6, and the image storage board 6 is connected to a laser beam installed at the rear. light source 7
The optical system 8 is arranged so that the light beam L emitted from the optical system 8 is scanned. In this case, the image storage plate 6 may be either a detection plate forming an electrostatic latent image or a plate made of an emissive phosphor, or both plates require pretreatment such as full exposure or removal of afterimages. In this case, the X-rays emitted from the X-ray tube 9 pass through the subject 2 and form a latent image on the image storage plate 6'. The subsequent readout process is exactly the same as in the case of FIG. 1 above.

This latent image reading device is disclosed in JP-A-54-31219 and JP-A-55-15025. In any of these methods, in order to obtain a high-quality image signal, it is necessary to narrow the scanning light beam and reduce the diameter of one pixel, and the disadvantage is that it takes a long time to read out the image.

For example, the size of the image storage board 6 is 400mm x 400mm.
mm, optical scanning is performed at a pitch of 0.1 mm, one pixel is separated by 0.1 mm in main scanning, and the sampling time per pixel is 0.5 mm. Assuming seconds, the time TI required for the entire scan is as follows.

TI= (40010,1)・(40'010.1)
- (Q, 5/106) = 8 (seconds) Therefore, the repetition cycle for obtaining a reproduced image requires 8 seconds at the fastest to obtain one image. In this way, it takes a long time to read out the image signal, but depending on the purpose of use, it is not necessary to read out the entire screen; for example, in medical observation using X-rays, it may be sufficient to image only a portion of the screen. There is. In this case, the scanning range can be small, so
Scanning time decreases in proportion to screen area.

An object of the present invention is to provide a latent image successive device that can change the reading range of a target image and save reading time as described above, and its gist is to store images two-dimensionally as latent images. A device that reads an image by optically scanning an image storage plate, which scans the scanning angle of view in the main scanning direction, which is the scanning direction of the light beam, and/or the scanning angle of view in the sub-scanning direction, which is orthogonal to the main scanning direction. It is characterized by having means for changing.

The present invention will be explained in detail below based on illustrated embodiments.

Prior to explaining the apparatus, the present invention will be explained in detail with reference to FIGS. 3 and 4. 3(a) and 3(b) show the trajectory of the two-dimensional scanning of the light beam L with respect to the image storage plate 6. FIG. In (a), for example, A (1, 2) represents the scanning spot in the second column of the first row, A (2, 3) represents the scanning spot in the third column of the second row, and d represents the scanning spot in the third column of the second row. The scanning angle of view on the image storage board 6 is shown. Also in (b),
Similarly to (a), B (1, 2) represents the scanning spot in the second column of the first row, and the scanning angle of view is, for example, (1/'2)d, which is 1/2 of (a). In other words, in (b), only the range indicated by (1/2)d on the image storage plate 6 is optically scanned. Similarly, the scanning angle of view in the horizontal direction is 172 in (a).
Then, the total number of pixels in (b) is 1/4 of that in (a), and the total scanning time is also 1/4 of that in (a).

In this way, if the angle of view for optical scanning is d in both the horizontal direction (main scanning direction) and the vertical direction (sub-scanning direction), the total number of pixels N is 1'J oo d 2 , and the number of pixels is Since the sampling time interval is constant, the total scanning time T is Too d 2 . Therefore, in the same way as in the conventional TI calculation described above, the optical scanning range of one image storage plate 6 is set to 200 m for the previous example.
mX200mm, the total scanning time T2 is T2= (20(110,1)' (20010,1)
-(0,5/10')=2 (seconds), and this scanning means is very effective in the case of images for which observation at a small angle of view is sufficient.

FIGS. 4(a) and 4(b) show modified examples of the scanning angle of view in FIG. 3, and hatched areas Da and Db represent scanned areas. In this way, the total number of pixels and total scanning time can also be reduced by optically scanning the necessary angle of view according to the observation target. For example, it is possible to reduce the total number of pixels and total scanning time. For the specimen, Fig. 4(a)
It is particularly effective to use a scanning range of .

FIG. 5 is an explanatory diagram of another means, and the display method is the same as that in FIG. 3. In (b), the scanning angle of view in the main scanning and sub-scanning directions is reduced to (1/2) d as in Figure 3(b), and the diameter of each spot light is set to the diameter r of the spot light in (a). It is assumed to be twice that of , that is, 2r. Here, if the sampling time interval is the same in (b), that is, the horizontal scanning speed is doubled, then C (1
, n) is twice as large as that of A (1, n). Also, the vertical spot spacing,
That is, C(1, n), C(2, n), C(3.

n) intervals are A(1, n), A(2, n), A(3,
If it is doubled compared to that of n), the scanning angle of view will be halved.
By doubling the diameter of the spot light and increasing the scanning speed, the total number of pixels and total scanning time in (b) are both 1/16 compared to (a). Therefore, if the total scanning time in (a) is 8 seconds, it will be 0.5 seconds in (b).

FIG. 6 is a block diagram of an embodiment according to the present invention, which also enables partial readout scanning mainly explained in FIGS. 3 and 4. A movable board 12 supported in the XY plane, that is, in a direction perpendicular to the image storage board 6 by a feed screw rod 10 and a guide rod 11, is disposed in front of the image storage board 6 fixedly placed on the YZ plane. By the rotation of the feed screw rod 10 driven by the transmission gear 13 and the transmission gear 14, the movable base plate 12 can move in an arbitrary movement range selectively determined in the Z-axis direction, that is, in the vertical direction.

A reflecting mirror 15 and a rotating polygon mirror 16 that rotates around the Z-axis direction at high speed are provided on the moving substrate 12. Further, a galvanometer mirror 17 that swings both horizontally and vertically is provided at the bottom of the movable substrate 12, and an optical path switching reflecting mirror 18 that can be moved away from the optical path by electric power is installed below the reflecting mirror 15. has been done. Moving board 1
A condenser lens 21, a mask 22, a collimator lens 23, and a reflection mirror 24 for converting the traveling direction of the light beam L are fixedly arranged diagonally below the laser light source 7 in order along the fixed direction. The light beam L is guided to the reflecting mirror 15 when the optical path switching reflecting mirror 18 is not present on the optical path. Here, the scanning angle of view in the main scanning direction by the galvanometer mirror 17 is narrower than the scanning angle of view of the rotating polygon mirror 16, and is variable.

The drive mechanism of the galvano mirror 17 is shown in Fig. 7(a).
, the bearing 3 shown in (b) and suspended from the moving board 12
A galvanometer mirror 17 is fixed to a vibration shaft 33 of a galvanometer 32, which is attached to the oscillating shaft 33 of a galvanometer 32 via a rotating shaft 31 parallel to the Y-axis. Further, a roller 35 is provided at the tip of a lever 34 extending upward from the galvanometer 32, and a cam 37 rotated by a drive shaft 36 is in contact with this roller 35. For sub-scanning, the galvanometer mirror 17 is swung according to a range via a roller 35 by the rotation of a cam 37, and in order to ensure this movement, the lever 34 is moved by a spring 38 to move the lever 34 through a roller 35.
is pressed against the cam 37 side.

FIG. 8 shows the drive mechanism of the optical path switching reflection mirror 18,
The switching reflection mirror 18 is fixed to a rotatable pivot shaft 40 vertically installed on the movable base plate 12, and is moved in accordance with the rotation of the solenoid 41 by the operation of a rotary solenoid 41 similarly attached to the movable base plate 12. Pin 42, rotation axis 4o
The switching reflective mirror 18 is connected via a lever 43 attached to the
can be rotated to move forward and backward with respect to the optical path.

This embodiment has the above-described configuration and has the following two effects.

That is, first of all, in order to obtain a large image of the entire screen, for example, the optical path switching reflection mirror 18 is retracted from the optical path, and the laser light source 7 emits the light beam L. The light beam L is once reflected by the condenser lens 21. After the light is focused and the intensity distribution is shaped by the next mask 22, it is made into parallel light by the collimator lens 14. Furthermore, this light beam L is deflected in an upward right angle direction by a reflecting mirror 24, is again deflected by a reflecting mirror 15 on the moving substrate 12, and enters a rotating polygon mirror 16 from the horizontal direction, where it is reflected again to accumulate an image. The image is formed on the plate 61-. At this time, the light beam L passes over the image storage plate 6 by the rotation of the rotating polygon mirror 16.
Scan in the horizontal direction on the Y plane. Here, when the feed screw rod lO is rotated by the drive mechanism, that is, the electric motor 13, the moving board 12 is moved downward a distance #d in the vertical direction of the screen.
, and the reflecting mirror 15 and rotating polygon mirror 16 also move downward. The optical system from the laser light source 7 to the reflection mirror 24 is fixed, but since the light beam L from the reflection mirror 24 to the next reflection mirror 15 is parallel light, the light beam L rotates without being affected by the distance between them. The light will be incident on the polygon mirror 16.

In light scanning to the image storage plate 6, main scanning is performed in the Y-axis direction by rotating the rotary polygon mirror 16, and sub-scanning is performed in the Z-axis direction by moving the movable substrate 12 downward. , the light beam L projected onto the image storage plate 6 on the xY plane
Since the incidence is almost perpendicular, an image without distortion can be obtained.

Therefore, in this case, it is possible to obtain an image with a large number of pixels, that is, a wide angle of view range corresponding to the scanning locus shown in FIG. 3(a). Furthermore, if the moving range of the moving substrate 12 is appropriately set, an image of the scanning range as shown in FIG. 4(b) can be obtained.

Furthermore, in order to obtain an image with a small angle of view as shown in FIG. The light beam L that has been deflected is deflected in the direction of the Garno mirror 17 by the optical path switching reflecting mirror 18 . The light beam L is then scanned and deflected onto the image storage plate 6 by the galvanometer mirror 17. In this case, the galvanometer mirror 17 performs main scanning in the Y-axis direction on the image storage plate 6 by the vibration of the galvanometer 32, and performs sub-scanning in the Z-axis direction by operating the cam 37. The angle of view in the main scanning direction of this galvano mirror 17 is smaller than that in the case of using the rotating polygon mirror 16, as described above, and if the angle of view in the sub-scanning direction is also made smaller, the angle of view in the main scanning direction will be as shown in FIG. 3(b). To,
If the angle of view in the sub-scanning direction is increased, the image corresponds to the image shown in FIG. 4(a). Furthermore, by arranging a condenser lens and a convex lens on the line connecting the galvanometer mirror 17 and the switching reflection mirror 18 to increase the diameter of the light beam L and to increase the main scanning and sub-scanning speeds, it is possible to increase the main scanning speed and the sub-scanning speed. ), but the desired image can be obtained at a fairly high speed.

In the embodiment, the common laser light source 7 is used even when the scanning angle of view is changed, but it may be provided separately.

As explained above, the latent image reading device according to the present invention is equipped with a mechanism capable of both obtaining an image with a large angle of view and reducing the scanning time by reducing the angle of view. The viewing angle of the target image can be easily switched and can be used effectively as needed.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram when an image by visible light is formed on an image storage plate and read out, Fig. 2 is an explanatory diagram when an image by X-ray is formed on an image storage plate and read out, and Fig. 3 ( a), (b),
4(a), (b) and FIG. 5(a), (b) are principle explanatory diagrams of the latent image reading device according to the present invention, and FIG. 6 and subsequent figures show an embodiment of the present invention, Figure 6 is its configuration diagram, Figure 7
Figure (a) is a front view of the galvanometer mirror drive mechanism, (b)
8 is a right side view thereof, and FIG. 8 is a front view of the drive mechanism of the reflection mirror for optical path switching. 6 is an image storage plate, 7 is a laser light source, 10 is a feeding rod, 12 is a moving board, 15 is a reflecting mirror, 16 is a rotating polygon mirror, 17 is a galvanometer mirror, 118 is a reflecting mirror for optical path switching, and 17 is a galvanometer. , 37 is a cam, and 41 is a rotary solenoid. Patent applicant: Canon Co., Ltd. Figure 2 Figure 3 Figure 4 11511f 1, -1/! d-, l

Claims (1)

[Scope of Claims] 1. A device for reading images by optically scanning an image storage board that stores images two-dimensionally as latent images, the scanning angle of view in the main scanning direction being the scanning direction of the light beam. and/or a latent image readout device characterized by having means for changing the scanning angle of view in the sub-scanning direction orthogonal to the main scanning direction. 2. The change in the main scanning angle of view is performed by The latent image readout device according to claim 1, wherein the latent image reading device is configured to change the sub-scanning angle of view by changing the scanning deflector to the image storage plate. 4. The latent image reading device according to claim 1, wherein the sub-scanning angle of view is changed by changing the range of the axis of the scanning deflector. A latent image reading device according to claim 1. 5. A latent image reading device according to claim 1. 5. A latent image reading device according to claim 1. The latent image reading device according to item 1.