Laser beam scanning system

[Detailed Description of the Invention]

The present invention relates to the system which scans the laser modulated acoustooptically, It is related with the system that laser A pime is modulated by either statically (bistatically) 2 values by various carrier frequencies beyond two or it so that especially a light spot may produce the image pattern located in a line with serial by two dimensions. The laser beam scanning system modulated acoustooptically, especially a raster scan system are a certain art for many years. Some satisfying system configurations are known. However, when the demand about speed, resolution, and alignment which grows increasingly develops the technique with the demand about shock printing, coloring of a paper, and Arrival at the island, some still more difficult problems have been produced as art progresses. If there is no special reason in addition to such a conventional method and this device and each is proving worth of that past performance, it is very desirable to use these method and this device for a possible place. many very high-speed laser scanning systems, especially printing -- use -- "To be -- in order to reduce a required scanning rate with a deflection device in the system of these -- and -- simultaneous -- standup falling time required of abnormal-conditions Bag layer -- increase -- a plurality of beams which have 2 or a focus beyond it for last reason -- with, the composition which carries out an intermediary scan is known. the acoustooptical modulation device energized by the carrier frequency beyond 2 or it for this to give (non-coincident) the beam of the non-consistency which can be modulated separately if needed -- with, an intermediary is there grade is attained. In an acoustooptical abnormal-conditions raster-scanning system by which a laser beam is deflected by one way with an optical instrument device, and is deflected in the usual direction by the acoustooptical modulation device which operates simultaneously on 2 or different subcarrier frequency beyond it, and intensity abnormal conditions are carried out, Each trial which agrees in the growing demand will produce the mutual abnormal conditions which are not desirable. Although two kinds of new techniques are explained with the device of the new example corresponding to it below, I will describe a little the device of conventional technology in which operation of some of the constituent children or some systems is shown before that. the [ the 361431st Sign of an United States patent, and / the ] -- although an acoustooptical laser beam raster scan device is shown in a 374403y item and 3935566 and the principle by the present invention can be applied to those devices There is nothing that mentions the solution subject by the present invention, or suggests the solution technique in these very thing. Although the device which gives U.S. Pat. No. 4000493 and 4053898 a raster scan type image display with an acoustooptical laser beam scanner is indicated, a subject called the spatial overlap to which the device by the present invention points cannot be said to have suggested the device of Grade and It was for there to be nothing and according to the present invention. Although it thinks that the object of the present invention touches indirectly by the above, and becomes clear gradually in the following explanation again, An acoustooptical modulation device Transverse formation(ed) so that it might debate, - Rust-Beam might be thought to be the laser which generates the beam of coherent light and it might be deflected with 2 or the beam beyond it which can be modulated to each which spreads in the slightly different direction, For example, it Brewing(ed) so that the modulated laser beam might be received and they might be deflected in the right-angled direction in the one direction, it is obtained in the easy composition which comprises deflection devices, such as a rotation mirror, and the superficial or cylindrical surface element against which a beam runs by two or more scanning patterns sequentially. according to the present invention -- a raster -- between the points (spot) of the image formation light in the adjacent scanning line of two at To -- A child -- a field decreases very much Up to the minimum in which an acoustooptical modulation device rotates around the axis of a laser beam in one technique by the present invention, and the light spot of most on one line can permit the light spot of most on the following line by this supposing it is not lost completely, It brings forward so that piling may decrease (or delayed). In other techniques by the present invention, the new raster scan made interwoven with each other is produced by two scanning light spots which separated the scanning line pitch at 3 times or the interval beyond it by deflecting a beam at a required angle in an acoustooptical abnormal-conditions machine. In this technique, since an overlap in the light spot with which an image display will be overlapped does not arise, cross protection is avoidable. The 3rd technique is allocated combining the two above-mentioned techniques during one composition. It is a figure showing the fundamental scanning system with which the principle of the present invention is applied in Drawing 1. The east of coherent light is given to acoustooptical modulation device 14, and the Kohdo is modulated by the beam which supports the image of the light spot located in a line one by one there, and it is projected on laser device 8 on rotation (many sides) mirror device 16. These are all a certain composition from the former. Rotation mirror 16 scans a beam horizontally so that the cylindrical drum of a big turning radius may be crossed to a line plane, i.e., surface element 18. it -- a scanning line is perpendicularly separated to Iso area by moving both surface elements 18 to a transverse direction, or rotating a cylindrical drum. Acoustooptical modulation device 14 gives two pieces or the light spot beyond it where transverse direction movement only of the required distance is carried out for simultaneous two or more scans of cylindrical surface element 18. Cylindrical surface element 18 of this example is a conductive drum for an optical printer etc. the composition of illustration is an understanding -- if it is having excluded the synchronous system, that itself is not a part of present invention, however a person skilled in the art since it is easy, in order to synchronize this device in the mode of at least one common knowledge in many modifications which can be used, it will be understood easily that a required means can be added. the figure of modulation device 14 taken in the direction of A-A of Drawing 1 -- the -- it is shown ina [ 2 ] figure in diagram. It is projected on this laser beam into optical element 20. Arrow 22 displays the direction of the horizontal scanning line which crosses cylindrical surface element 18. It Foundation so that a sound wave which piezoelectric transducer 24 which answers 2 or the electronic carrier frequency wave beyond it displays by 26 may be generated. This sound wave 26 carries out, modulates - The beam, and it spreads so that it may deviate horizontally. Based on a punctiform signal which is recalled in an optical display according to a conventional system and which was located in a line one by one, the intensity abnormal conditions of this sound wave 26 are carried out again. 2 or the frequency beyond it is used so that the raster scanned as a result may be performed by two or more scanning lines. the -- it is shown inb [ 2 ] figure in diagram, a pair of the points, i.e., light spots 31 and 32, in the adjoining scanning line which overlaps all over common field 33 which finally produce. Although such overlap of a certain grade had to bear in the composition of Follow-up technology, in order to produce a continuous perpendicular line, the light spot had to be larger than the scanning line interval. Since laser A pime which produces light spots 31 and 32 has frequency fluctuated by the quantity of the carrier frequency which produces diffraction (being dependent on angle orientation of the laser beam by a sound wave), The two beams will interfere in the field of overlap, and will produce the undesirable abnormal conditions of frequency equal to the difference of two carrier frequencies. A device which has so far been explained, and its operation express the conventional technique. In overlap field 33, interference of two beams produces the mutual abnormal conditions which are not preferred. These abnormal conditions that are not preferred arise on the frequency of the following difference. Co f.- et al. [11, however f3 are mutual abnormal-conditions generation frequency, and are a carrier frequency in case f and a Lima electric converter drive. Along the horizontal scanning line, this abnormal-conditions depth is the maximum and decreases to the positive and negative perpendicular direction from this line. According to the present invention, though generation of mutual abnormal conditions is not lost completely, it decreases very much. or [ that this makes the interval of one new technique, i.e., a scanning light spot, increase the structure which comprises the composition of the conventional technique, and reduces an overlap in a light spot by this ] -- or in order to lose, in accordance with the technique of making the frequency difference of a career increase, it is convertible for a new structure by the present invention. a scanning line interval -- the -- it is maintained when only angle 8 (measuring from the line of a right-angled direction in the image scanning direction) rotates the modulation device shown inC [ 2 ] figure. This corresponding light spot pattern is shown in the 2ndd figure. An improvement of this mutual abnormal-conditions effect will consider being easily understood by it, if far small overlap field 33' is seen. Both light spot is positioned mutually, solves and that of this overlap field is lost so that it may be displayed by circle 32'' and 31' of a dashed line. The above-mentioned angle arises by rotating the modulation device 14 around the ball defined by the center line of two or more beams by which for Arrangement is carried out with modulation device 14, and, thereby, the light spot on a certain scanning line is brought to the corresponding light spot on the next scan. This technique has some strong points which help to lessen the mutual abnormal-conditions effect. One strong point is because between the centers of a beam is greatly separated, and it decreases, without the peak amplitude of the point of the center based on [ the / two ] beams reducing contrast. The 2nd strong point is that an effective overlap (overlap) field is small. There is the 3rd strong point in producing a smooth effect in sine wave change of the exposure intensity with which a motion of a light spot integrates along a x direction and which the degree a of rotation angle produces as a result by this. It is that need big frequency between [ which are used for driving an electronic sound converter to separate greatly / two ] waveforms, and only a horizontal slight distance produces exposure change by this. When 0 was taken at angle 0 according to research, mutual abnormal conditions were 33%, and when Ri was taken at angle 450, the maximum abnormal conditions were 13%. The Clique value of it is carried out for producing printing density abnormal conditions, and the latter abnormal-conditions depth can come under a bell, when using electrophotographic printing technique. This technique is applied from oo of angle 8 to the value of a certain range between 900. This optimal value will be determined by the zone of the acoustooptical abnormal-conditions machine which can be used. Above-mentioned acoustooptical modulation devices are two or more modulation frequency again, with intermediary use may be carried out. According to the 2nd example of the present invention, the basic composition shown in Drawing 1 arranges acoustooptical modulation device 14 by another method, and is constituted. Drawing 3 saw modulation device 14 from the direction of B-B. While piezoelectric transducer 24' which produces zero-order beam 10' like illustration is not working, the entering laser beam passes through modulation device 14'' by a straight line. However, according to the present invention, the electric wave impressed to converter 24' deflects beam 10 at a different angle for every frequency from which illustration differs. It is as follows when a formula shows this. Namely, =f.10$ They are [2} however f, and the modulation frequency that made Lima selection. It jumps over the technique that a scanning beam is separated widely perpendicularly in this way (it is rlaced to jn), and it is applied with a scanning mode. The example portion of one rather fundamental scanning pattern is summarized in the following table. Table 1 Table 0 it Such and frequency is set up in the 1st scan to resemble scanning lines 1 and 4 and position a beam. By the following line, scans 3 and 6 are scanned and it is scanned like the following. When it is assumed that the difference of frequency required for this technique is scanning the line by which two light spots adjoin each other, it is 3 times the required difference. Since a light spot is separated only in this big quantity, a spatial overlap is lost and the interference between two beams stops however, arising. Easy Drawing 1 of explanation of a drawing is a functional diagram of the fundamental scanning device which can apply the present invention. the -- the [a / 2 / figure and ] -- the [b / 2 / figure and ] --c [ 2 ] figure and the 2ndd figure are diagrammatic figures showing the operation and structure of a device by the present invention conventionally after comparing with a device. Drawing 3 is a diagrammatic figure showing the acoustooptical modulation device used with the device by the present invention. 8 ...... laser device, 10 ...... beam, 14 .. - .. - acoustooptical modulation device, 16 ...... A rotation mirror, 18 ...... The cylindrical surface (line surface), i.e., a surface element. FIG.I FIG.2 (o])

FIG.2 [b]

FIG.2(c) FIG.2(d) FIG.3