JPS6173469A - Picture reader - Google Patents

Abstract

PURPOSE:To reduce the variation of photodetecting efficiency which is due to the unevenness of optical systems by constituting a light guide so that a scatting space or a scattering body for dispersing incident light into the light guide on the light incidence side is formed and other surfaces except the surface on the projection side reflect light internally without leaking the light to the outside. CONSTITUTION:The light guide 8 is a carrying means for carrying a picture vertically to the scanning direction of light flux and the scattering body 9 consisting of a translucent resin and dispersing light into the light guide 8 leads the light to a photoelectric converter 11. The front side of the incident side and the outlet of the projection side are finely ground to prevent light from attenuation and the sides are prepared for internal reflection. When it is defined that the ratio of light led into the photoelectric converter 11 and converted into an electric signal to a fixed light from a light source is the photodetecting efficiency, the capacity of the light source 1 can be reduced in accordance with the reduction of dispersion and attenuation in an optical path on the way and the improvement of the photodetecting efficiency, and in case of the same capacity of the light source, the gain of a preamplifier 12 can be reduced, so that the influence of noises generated in the preamplifier circuit can be reduced.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an image reading device, and particularly to an image reading device that efficiently transmits light from each pixel of an image to a photodetector, and that the efficiency does not depend on the pixel position. The present invention relates to a light guide suitable for transmitting substantially the same amount of light to a photodetector when having the same gradation information.

[Background of the invention]

If the amount of light transmitted from pixels with the same gradation information to the photodetector is not constant and the light detection efficiency is not the same, that is, if an uneven optical system is used in which the light detection efficiency varies depending on the pixel position, it may be difficult to Therefore, it becomes necessary to perform appropriate photodetection efficiency correction. If you use an optical fiber array or a side reflection type guide that determines the direction of light travel simply by using a reflective surface, which is relatively inexpensive compared to V/Z or mirrors, as a condensing optical system, the light detection efficiency will be uneven. It cannot be corrected for specific parts where the sensitivity is severe and the detection efficiency changes drastically. Therefore, the read image information contains false information and artifacts. In addition, since there are parts in the light guide where the amount of light received is extremely different, there are parts where the gradation information that is obtained when detecting the amount of light in time series with the light receiving system overlaps, that is, the dynamic gradation information that can be guaranteed. There was a period of time when the range decreased and the quality of the scanned image deteriorated.

[Purpose of the invention]

An object of the present invention is to solve the problem with conventional devices and to provide an image reading system that is inexpensive and can be read without introducing artifacts or deteriorating image information. [Summary] The present invention is a method of arranging a light scatterer on the light kite entrance surface in order to reduce the optical non-uniformity of the condensing optical system that causes the problem. As a result, the path of light to the photodetector is averaged, specific fluctuations and differences in photodetection efficiency are reduced, and the correction operation becomes effective, making it possible to achieve the above objectives. Ta.

[Embodiments of the invention]

Hereinafter, a practical example of the present invention will be explained with reference to FIG.

To explain the components of the embodiment, 1 is a light source, and 2 is a light beam emitted from the light source, which in this example is a parallel light beam like a laser beam, but it does not necessarily have to be parallel. 3 is a light deflection element that changes the direction of light, such as a vibrating mirror,
The light beam is repeatedly scanned in a high-speed straight line. 1; A light focusing optical system that can focus the light beam to a predetermined size and keep the size constant on the image plane 6, for example, l-θ
Shi/zu etc. 5 represents the light beam that is focused by the light focusing optical system in 4. 6 represents the image to be read, such as a frame, 77"i, and the feed that sends one image perpendicular to the scanning direction of the light beam. The mechanism 8 is a scatterer 9 made of translucent resin that diffuses the light into the light kite 9, and a light guide 9 that guides the light from the light beam 11 to the converter. It is often used to prevent light from attenuating, and the sides reflect internally.
Constructs an 11-plane reflective light guide. 10 represents the diffused light that is diffused by the scatterer 8 and propagates within the light guide 9. 11 is a photoelectric converter such as a photodiode or photomultiplier tube that converts light into an electrical signal; 12B is a preamplifier circuit; 13 is A;
/D converter.

Next, how does this actual example work? explain.

The light emitted from the light source 1 passes through a light deflector 3 and a light focusing optical system 4, and is focused onto an image 6 (for example, a film) surface into a micro-diameter light beam corresponding to the pixel size, and is focused in accordance with the repetition period of the light deflector. , repeats linear scanning on the image plane. This will be called main scanning.

Further, the image 6 is fed perpendicularly to the main scanning direction by the feeding mechanism 7 by a length of one pixel size during one main scanning at a constant speed or in steps. This is called full sub-scanning. In this way, the light beam sequentially scans the entire image. On the other hand, the amount of light transmitted through the image 6 is modulated in accordance with the information contained in the image.

For example, for film, if the input light amount is 11,
Amount of light after passing through a dense area ■. is L)=I+X1
It becomes 0-o. Therefore, in parallel with the scanning of the minute light beam, the amount of transmitted light is measured as an electrical signal for each pixel position by the photoelectric converter 11, and after being amplified by the preamplifier 12, the signal is converted into an A/
By inputting it to the D converter 13, it becomes possible to obtain digital image information with a density corresponding to the pixel position. Here, light is transmitted from each pixel position in the main scan to a photoelectric converter 11 that converts the amount of light into an electrical signal. A role to guide? These are the scatterer 8 and the light guide 9. Next, the function of this front scattering side reflection type light guide will be explained. lI! ! If the ratio of the amount of light that is guided to the photoelectric converter 11 and converted into an electrical signal with respect to a constant amount of light from the light source without inserting the I image 6 is called the photodetection efficiency, the dissipation and attenuation in the intermediate optical path will be small. The better the light detection efficiency is, the smaller the capacity of the light source 1 can be, and in the case of the same light source capacity, the gain of the preamplifier 12? Therefore, it is possible to reduce the influence of noise generated inside the preamplifier circuit.

Furthermore, if the photodetection efficiency varies slightly depending on the pixel position in the main scan, the data converted into an electrical signal of the light amount in a specific part where the f-shift is large is transmitted to the photodetector system (photoelectric converter). 11. The response characteristics (frequency characteristics, hysteresis, etc.) of the preamplifier 12) f: is reflected, so using the once measured photodetection efficiency, all light amount data is fully corrected to provide accurate Iy3JG”: information. Retrieval can be difficult and cause artifacts in the image.

FIG. 2 shows a comparison of the light detection efficiency between a simple reflective light guide and a front diffused side reflective light guide. In a simple reflective light guide, the light detection efficiency at the pixel position where the image 6 and the transmitted light directly enter the photoelectric converter 11 without being reflected on the side surface of the light guide is extremely high; A large proportion of the light is dissipated, and the light detection efficiency in areas other than the center becomes low, resulting in the occurrence of a singularity. On the other hand, in a front-scattering, side-reflecting light guide in which the scatterer 8 is arranged, the light is diffused within the light guide as shown in Figure 1, and the light at any pixel position reaches the photoelectric converter at a similar rate. 11, the light detection efficiency is made uniform as shown in FIG. 2, the overall light detection efficiency is good, and good image information can be obtained.

Although this embodiment is an example in which a scatterer is arranged on the incident side of a planar light guide that supports one-dimensional scanning of light, the effects of the present invention are not limited to this, and the effects of the present invention are not limited to this. The same effect as Example 911 can be expected from a light guide compatible with scanning, for example, a pyramid-shaped light guide in which a scatterer is arranged on the incident surface. Furthermore, although this embodiment is an example in which transmitted light whose light intensity is modulated by an image is guided to a photodetector such as a photoelectric converter by a light guide, the gist of the present invention also applies to the case where reflected light whose light intensity is modulated by an image is guided. It is possible to expect the same effects as in the example without changing. Furthermore, the same effect as in this embodiment can be expected when the intensity of the phosphor corresponding to the image recorded on the stimulable phosphor is measured by irradiation with a light beam and the image information is obtained. Furthermore, the same effect as in the embodiment can be expected even when the light guide entrance surface is made of a scattering surface such as frosted glass, with or without a scatterer.

〔Effect of the invention〕

According to the present invention, fluctuations in photodetection efficiency due to non-uniformity of the optical system are reduced, so deterioration in the quality of read image information can be reduced. Furthermore, an inexpensive light guide system can be used as the condensing optical system.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a photodetection efficiency diagram. 1... Light source, 2... Parallel light beam, 3... Light deflector,
4... Light focusing optical system, 5... Focused light beam, 6... Image, 7... Feeding mechanism, 8... Scatterer, 9... Light guide, 10... Diffused light, 11 ...Photoelectric converter, 12
...Preamplifier, 13...A/D converter.

Claims (1)

[Claims] 1. A light source, a scanning mechanism and a converging optical system that scan the light of the light source corresponding to the pixels of the image, and transmitted or reflected light whose light amount is modulated by the image, or secondary induced light. In an image reading device comprising a light guide that guides fluorescence and a side light section that measures the amount of transmitted/reflected or fluorescent light, the light guide has a scattering section or a side light section that diffuses the incident light inside the light guide on the light incident side. It has a scatterer and the other surfaces, except for the surface on the exit side, are configured to reflect internally so that the light does not escape to the outside, or are configured to internally reflect the light so that the light does not escape to the outside. An image reading device characterized by having a structure that refracts light.