Kazuo Minoura

Laser recording and image-quality evaluation

Various kinds of printers electrophotographic printers ink jet printers thermal printers etc. have been commercialized especially for DTP. The authors however have been unsatisfied with the image-quality of these printers. A laser recording apparatus was made for our study which is composed of a laser diode a polygonal mirror and a F-theta optical system. The recording apparatus selectively provides high density pixel (600 900 or 1 200 dpi). The gradation of each pixel is obtained by modulating the pulse width of the laser diode oscillation. We used the silver halide paper (PD-100WP Fuji Photo Film Co. Ltd. ) with the good spectrum sensitivity for the laser diode of 780 nm wavelength. The recorded image samples with three kinds of pixel densities and with gradation levels ranging from 16 to 166 were used for being evaluated by sixteen persons. As a result of analysis on the evaluated data we found out some relations between pixel densities and gradation levels for the satisfactory image-quality. 2.

Scanning Optical System Of The Canon Laser Beam Printer

We describe studies on the scanning optical system for compact and inexpensive Canon laser beam printer (which we call LBP). Based on Canons historically accumulated laser scanning optical technologies, our originally developed scanning optical system has the two functions of fθ-characteristic and deflection error compensation (we call the scanning optical system fθ-DEC), comprising a polygonal mirror scanner and toric lens as key components. As for the design, compactness and inexpensiveness of the fθ-DEC scanning optical system was investigated based on our theoretical and analytical study on fθ-lens for LBPs. On the manufacturing side, exclusive manufacturing equipment was developed for each of the above mentioned key components for effective mass production. In this paper, the theory, design, and manufacturing technologies for our fθ-DEC scanning optical system are presented. In addition, as an application example, Canon LBP-CX is introduced, where the above technologies have been integrated.

A Study On Laser Scanning Systems Using A Monolithic Arrayed Laser Diode

It is well known that a monolithic arrayed laser diode is effective for a high-speed laser beam printer. In terms of the angular relation between the arrayed direction and the laser beam scanning line, two typical laser scanning optical systems using a monolithic arrayed laser diode are comparatively discussed in this paper. As for the first optical system, the arrayed direction is slightly tilted from the scanning lines direction. While this system has an advantage of easiness in the data processing technique in comparison with the other optical system, we have to pay attention in designing and manufacturing this optical system in terms of accuracy and complicateness. The second optical system forms a striking contrast to the first. The lasers arrayed direction of the second optical system is perpendicular to the laser beam scanning line. In this system, we need no such particular designing nor manufacturing as in the first one described above, but interlacing scanning method and the relevant data processing technique. Through comparing the above two systems, we are discussing optical issues. As the conclusion, we think, the second system of interlacing method would become popular in consideration of the future advances in data processing technique.

Optical Lens System For Laser Beam Printer

In the scanning optical system for laser beam printer, so-called f-0 lens is utilized to provide a scanning spot of constant velocity from deflected light beam having constant angular velocity. Then, f-8 lens is designed to have proper amount of residual distortion. One important point at the optical design of such kind of optical system is to find out the relationship between distortion and point spread function of the lens. In this report, the relationship is made clear by using aberration theory. With some designed examples it is shown that f-8 lens is suitable for scanning purpose, and that the lens makes us highly effective use of laser beam energy by reducing the deformation of point spread function with respect to the deflection angle of beam. As the example of application, the optical elements for semi-conductor laser scanning system are presented.

High-quality image recorder and evaluation

As the desk-top publishing market has been rapidly expanding, high-quality image output technologies have been increasingly required; especially as to restoration for images with gradation like photographs. To meet this requirement, the authors developed a new high quality image recorder and tried some experiments of simulation image recording. In the high quality image recorder, the laser scanning optical system is used, including an anamorphic optical system. The laser spot diameter in the deflection plane is small as 30 micrometers in the image plane, and the scan length is large as 300 mm. A polygonal mirror is used as the beam deflector and the scanning optical system corrects the tilt error of the polygon facets. By using this image recorder, the authors obtained simulation image samples, which is based on the bi- level pixel of 1200 dpi density. The simulation image samples mean halftone images with some screen rulings. The simulation procedure and the result of the examination are reported.