【正文】 first given number of electrical pulses for deenergizing said first carriage driving means and then energizing said second carriage driving means, said signal means being further operative upon receiving a second given number of electrical pulses to de energize said second carriage driving means and the n to energize said first carriage driving means. References Cited in the file of this patent UNITED STATES PATENTS 1,455,795 LoganMay 22,1923 1,744,642 KondoJan. 14,1930 1,814,701 IvesJuly 14,1931 2,123,276 EckerlinJuly 12,1938 2,506,141 DrouinMay 2,1950 2,527,338 StamnOct. 24,1950 2,575,367 StrongNov. 20,1951 2,702,393 MertonFeb. 22,1955 745,919 Great BritainMar. 7,1956 OTHER REFERENCES Jenkins and White,”Fundamentals of Optics,”second edition,1950 McGrawHill Book Co.,Inc.,New York,.,pages 247249.(C0py in ) 濟(jì)南大學(xué)畢業(yè)設(shè)計(jì) 外文資料翻譯 12 濟(jì)南大學(xué)畢業(yè)設(shè)計(jì) 外文資料翻譯 13 United States Patent Office, Ser. No. 739,123 網(wǎng)格劃 線機(jī) John T Ferris, Houston, Tex. 摘 要 本發(fā)明涉及到網(wǎng)格劃線機(jī)，更特別是 ，此設(shè)備為得到準(zhǔn)確的橫向劃長度廣泛的空白網(wǎng)格給與保障。 (in FIG. 2) to the same distance to the right thereof. After the circuit of motor 8 has been opened, a delayed signal closes the circuit of motor 7 to move carriage I to the right in FIG. 2 and, hence, prism 19 first toward and then beyond prism 18 to the original position, shown in FIG. 2. Again, electrical pulses are fed 濟(jì)南大學(xué)畢業(yè)設(shè)計(jì) 外文資料翻譯 6 to the counter and control circuit 24 until in response to appropriate signal the circuit of motor 7 is opened. Subsequently, motor 8 is energized and the cycle repeated. Therefore, it is apparent that the carriages1and 2 can be moved along over indefinite lengths in step by step stages measured in terms of onefourth wave length of monochromatic light source 11. Such apparatus is particularly adapted to produce elongate grids by a novel means. Adjacent to the path traveled by the carriages1 and 2 is secured an elongate grid blank 30。 FIG. 2 is a schematic plan view of the ruling machine. Referring now to the drawing, my grid ruling machine prises two carriages l and 2 separately driven along .well machined ways by any conventional drive means such .as pinions 3 and 4, engaging racks 5 and 6 along the machined ways. Each gear 3, 4 is driven by an electric motor 7 and 8, preferably of the servo type so that the velocity, starting and stopping of the carriages l and 2 along the ways, can be maintained under close control. As is well known, the desired velocity control is achieved with a servo motor by modifying the current delivered thereto in response to variations in speed actually delivered thereby Butin any event, the specific drive means employed for the carriages is not material and the motors and gears described are shown by way of illustration only. Other speed control mechanisms such as speed reducers can be utilized to supplement the means shown. Moreover, other mechanisms such as constant tension springs or even gravity may be 濟(jì)南大學(xué)畢業(yè)設(shè)計(jì) 外文資料翻譯 4 substituted as drive means. The important consideration in the apparatus to be hereinafter described is that means be provided to start, stop and otherwise control with extreme accuracy the movements of the carriages l and 2. The extent of movement of the carriages l and 2 is closely controlled by an interferometer 10 mounted thereon. The interferometer includes a source of monochromatic light, such as a cadmium vapor discharge tube 11 coupled with a narrow band filter 12. The near monochromatic light issuing from filter 12 is passed through a collimating lens 13 which directs a column of light into a dividing prism 14, prising tw0 306090 degree prisms 15 and 116 cemented together. Significantly, at least one of the prisms 15, 16 is aluminized at their union face 17 so that equal amounts of light will be reflected and transmitted by the plane of union, the reflected light being designated by the arrows R and the transmitted light by the narrows T. From the dividing prism 14 the reflected and transmitted light R and T pass into tetrahedral or corner prisms 18 and 19, respectively, which characteristically reflect light back along a path parallel to its path of entry, even though the prism is displaced in any direction transverse to such path of entry. After being reflected from their respective tetrahedral prisms l8, 19, the reflected and transmitted light R and T return to the dividing prism 14 where each is again divided by the plane of union 17. Here we are concerned with the transmitted ponents of the originally reflected light R and the reflected ponents of the originally transmitted light T both issuing from prism 14 along the lines R T toward a lens 20 which controls the diameter of the column of light impinging upon a shield or mask 21 having an annular aperture 22 there through which permits only a ring of light coincidental there with to pass and impinge upon a photoelectric cell 23 which converts pulses of light into electrical pulses. It will be noted that all ponents of the interferometer 10 are mounted on one carriage l except only one of the reflectors or tetrahedral prisms 18 which is mounted on carriage2 to move therewith. As is well known in interferometers, r