JPH0285972A - Image reader - Google Patents

Abstract

PURPOSE:To inexpensively and sufficiently obtain reading accuracy by connecting a photoelectric converter to the end face of a convergence body formed with a light input layer whose front plane is formed in a coarse plane, a light introducing layer in which optical fibers are arranged in sheet shape on its back side, and a reflection layer of sheet shape being formed at the back side of the light introducing layer. CONSTITUTION:The convergence body 20 is formed with the light input layer 20a, the light introducing layer 20b, and the reflection layer 20c, and the light input layer 20c, and the light input layer 20a of sheet shape forming the coarse plane is arranged at the front plane of the light introducing layer 20b, and the reflection layer 20c of sheet shape is formed at the back plane. The end faces confronting with the photodiode 15 of an optical fiber sheet are bundled in circular shape. Also, the reflection layer 20c of sheet shape is formed by the vapor-deposition of aluminum or the adhesion of aluminum foil or tin foil, and a laser beam received by the convergence body 20 is diffused by the light input layer 20a. The laser beam made incident from the light light input layer 20a is transmitted in the light introducing layer 20b while being prevented from being emitted to the outside by the reflection layer 20c, then, emitted to the photodiode 15. In such a manner, it is possible to obtain inexpensive and sufficient reading accuracy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention irradiates a scanning laser beam onto an image medium such as a film, an original, or a phosphor on which a radiation latent image is accumulated,
The present invention relates to an image reading device that receives and detects the obtained light to read image information.

[Background of the invention]

Image reading devices that read digital image information from image media such as film, originals, or phosphors on which latent radiation images are stored scan the entire screen of these image media using a spot-shaped scanning laser beam using a polygon mirror, etc. This is done by irradiating the

When the film surface is irradiated with scanning laser light, the transmitted light is irradiated, when the scanning laser light is irradiated on the document, the reflected light is irradiated, and the scanning laser light is irradiated onto the phosphor on which the radiation latent image has been accumulated. When this occurs, the photostimulated light obtained from the phosphor is received and detected as optical information, and guided to a photoelectric converter.
Digital image information is obtained by subjecting the amount of light received and detected to photoelectric conversion and A/D conversion in time series.

Optical information obtained from an image medium by scanning light in a line is focused by a condenser and guided to a photoelectric converter. Conventionally, a bundle of optical 7-eye bars has often been used as a condenser. .

The optical fiber bundles were bundled into a linear rectangular end face on the light-receiving side, and a circular end face facing a photoelectric converter such as a photomultiplier.

[Problem that the invention seeks to solve]

The optical fiber bundle bundled into such a special shape requires many man-hours to manufacture, resulting in an expensive condenser, and the cost ratio of the fiber bundle to the image reading device is high.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading device that is inexpensive and includes a light condenser with sufficient light transmission efficiency, and therefore is inexpensive and has sufficient reading accuracy.

[Means for Solving the Problems] The above object is to irradiate a scanning laser beam onto an image medium so that transmitted light, reflected light, or stimulated light is received by a condenser and guided to a photoelectric converter. In an image reading device that converts the photoelectric conversion into digital image information by performing A/D conversion after the photoelectric conversion, the light condensing body has a light entrance layer with a rough surface on the front side and an optical layer on the back side. This is achieved by an image reading device comprising a light guide layer in which fibers are arranged in a sheet shape, a sheet-like reflective layer behind the light guide layer, and a photoelectric converter connected to the end face of the light condenser.

〔Example〕

FIG. 1 shows an embodiment of an image reading device of the present invention, in which an X-ray film is used as an image medium and the image is read by receiving transmitted light of a scanning laser beam.

In the figure, 11 is a semiconductor laser that emits infrared rays of about 780 nm, and the laser beam is converted into a dot-shaped parallel beam by 12 collimator lenses, and then reflected by the surface mirror of polygon mirror 13, which is a rotating polygon mirror, to become a scanning beam. By further passing through the fθ lens 14, the light becomes a scanning lens light that performs linear scanning at a constant speed.

The scanning laser beam is repeatedly scanned and irradiated at right angles to the X-ray film F moving in the direction of the arrow. There is a film F behind the scanning laser beam through the X-ray film F.
A light condenser 20, which will be described later, is provided adjacent to the light condenser 20, and all the spot-shaped laser beams transmitted through the X-ray film F by scanning are condensed by the light condenser 20. The output from the photodiode 15 passes through an amplifier 16, a logarithmic amplifier 17, an A/D converter 18, and a shading correction circuit 19, and is recorded as an image memory M. be done.

Figure 2-A shows a light collector 20 and a sheet-shaped light collector 20.
A photoelectric converter is attached to the end face of the converter, and a photodiode 15 is used as a preferable example of the converter.

The condenser 20 of this embodiment is formed of a light entering layer 20a, a light guide layer 20b, and a reflective layer 20c, as shown in FIG. 2-B. The light guide layer 20b is formed by arranging optical fibers having a diameter of 150 to 160 μm into a sheet, and is long enough to cover the film width of the X-ray film F of 3500 mm. A sheet-like light incident layer 20a with a rough surface is arranged on the front side, and a sheet-like reflective layer 20c is formed on the back side.

Photodiode 15 of this optical fiber sheet
The end faces facing each other are bundled in a circle. The diameter of this circular end face is 10 mm or less. This area is large enough to be fully included in the light receiving surface of the photodiode. Further, the sheet-shaped reflective layer 20c is formed by vapor deposition of aluminum or pasting of aluminum foil or tin foil. Laser light received by the light condenser 20 is diffused by the light incident layer 20a.

The laser light incident from the light incident layer 20a is prevented from being emitted to the outside by the reflective layer 20c, and then transmitted through the light guide layer 2Ob and emitted to the photodiode 15.

Figure 12-C shows a fiber sheet 21 as another embodiment.
This is what is shown. This optical fiber sheet 2
1 consists of a light guide layer 21b and a reflective layer 21c.

The outer circumferential surface of the optical fibers of the light guide layer 21b arranged into a sheet shape is a rough surface.

However, it is also effective to form a roughened surface only on the light-receiving surface of the optical fiber outer peripheral surface of the light-guiding layer 21b arranged into a sheet. This rough surface is designed to play the role of the incident light N 20a.

The reflective layer 21c is formed into a sheet shape by vapor deposition of aluminum or by pasting aluminum foil or tin foil, as in the previous embodiment.

Further, as shown in FIG. 2-D, another embodiment is one in which another diffusion plate is arranged in front of the light guide layer 22b of the optical fiber sheet 22. This diffuser plate diffuses the laser light in advance. The laser light thus diffused is prevented from being emitted to the outside by the reflective layer 22c, and is transmitted to the photodiode by the light guiding layer 22b.

In addition, in the embodiment shown in FIG. 2-c, it is also effective to arrange a diffusion plate shown in FIG. 2-D on the entire surface of the light incident layer 21a of the condenser 21.

The light condensers 20, 21, 22 having the above configuration have almost the same structure as the optical fiber ribbon tape (product name), but this is used as a light condenser, and the end face of the sheet-shaped light condenser is The light-receiving part of the photodiode 15 is directly attached, and the light-receiving part of the photodiode 15 has a size and shape that exactly covers the end surface of the light condenser 20, and has a wavelength of 780 nm.
It has good sensitivity characteristics to infrared light.

When adopting such a configuration, it has a light transmission efficiency of at least 1% or more with respect to the transmitted light of the X-ray film F,
After the light is received by the photodiode 15, it passes through the amplifier 16 and reads image information with less noise.

Note that even if the transmitted light of the X-ray film F has the same luminous intensity,
Differences occur in the light received by the photodiode 15 depending on the scanning position of the scanning light with respect to the condenser 20, but since this difference always occurs under certain conditions, actual measurement was performed using an X-ray film with uniform density across the entire screen. It is easy to program a program to make corrections from the data obtained by

FIG. 3 shows an embodiment of an image reading device for reading an image of a radiation latent image accumulated on a phosphor. In the figure, 31 is an X-ray generator, and H is a subject such as a human body. The X-rays generated from the X-ray generator 31 pass through the subject H and form a latent image on the stimulable phosphor detector 32.

On the other hand, a semiconductor laser 33, an electromagnetic mirror 34, and a condenser 20 are mounted on the mounting base 35, and are moved and scanned in the vertical direction. The near-infrared spot-shaped laser light generated by the semiconductor laser 33 and traveling straight is converted into scanning light by the electromagnetic mirror 34 that rotates back and forth, and transmitted through a lens system (not shown) to be radiated as uniform scanning light. The phosphor detector 32 is linearly scanned and irradiated in the lateral direction. The condenser 20 is configured to be located close to the stimulable phosphor 32 by being irradiated with near-infrared laser light. The light condenser 20
is the same in shape and characteristics as the previous embodiment, but a photodiode 36 with characteristics matching the spectral characteristics of stimulated light is used as a photoelectric converter attached to the end face of the condenser 20. Further, the light receiving portion of the photodiode 36 may be provided with a filter that cuts off near-infrared light. The photoelectrically converted output of the photodiode 36 is recorded as an image memory M via an A/D converter 37 and a controller 38.

〔Effect of the invention〕

The image reading device equipped with the light condenser according to the present invention is inexpensive and has sufficient reading accuracy.

[Brief explanation of the drawing]

FIGS. 1 and 3 are configuration diagrams of two embodiments of the image reading device of the present invention, FIG. 2-A is a perspective view of the connection between a condenser and a photodiode, and FIG. 2-B is a diagram used in the present invention. Fig. 2-0 is a block diagram of another embodiment of the light condenser used in the present invention, and Fig. 2-D is a block diagram of another embodiment of the light condenser used in the present invention. It is a block diagram of another Example. 11.33...Semiconductor laser 12...Collimator lens 13...Polygon mirror 14...f
θ lens 15.36... Photodiode (photoelectric converter) 16... Amplifier 17... Logarithmic amplifier 18... A/D converter 19... Shading correction circuits 20 to 22... Light condensing Body 20a-22a...
Light entrance layers 20b to 22b...light guide layers 20c to 22
c... Reflective layer 3I... X-ray generator 32... Stimulable phosphor day techno 34... Electromagnetic mirror D... Diffusion plate H... Subject M... Image memory

Claims (2)

[Claims] (1) Transmitted light, reflected light, or stimulated light obtained by irradiating a scanning laser beam onto an image medium is received by a condenser, guided to a photoelectric converter, and subjected to photoelectric conversion, after which it is converted into an A/D converter.
In an image reading device that converts into digital image information by performing conversion, the light condensing body has a light entrance layer with a rough surface on the front side, and a light guide layer with optical fibers arranged in a sheet shape behind it. An image reading device further comprising a sheet-like reflective layer formed behind the condenser, and a photoelectric converter connected to an end face of the condenser. (2) The image reading device according to claim 1, wherein the photoelectric converter is a photodiode.