Патент USA US2133138код для вставки
Oct. 11, 1938. F_ HAMACHER 2,133,138 STROBOSCOPE Filed May 4, 1936 Fig.2. 4» f, // za 24 /6 l4 ~ 2/ I --F i 27 l mg; . ,3 n I. II - In ill/34mm - lllllll 22 36 ‘I | 2s N ze ‘ —— VACUUM TUBE OSCILLATOR ~-z5 1V4 -— / —— Inventor‘ -. Fritz I-Iam acher, :‘ Patented Oct. 11, 1938 2,133,138 ‘UNITED STATES PATENT OFFICE 2,133,138 STBOBOSCOPE Fritz Hamacher, Spandau-Ruhleben, Germany, assignor to General Electric Company, a corpo ration of New York Application May 4, 1936, Serial No. 77,880 In Germany May 24, 1935 13 Claims. (Cl. 88-14) My invention relates to stroboscopes and concerns particularly such apparatus for viewing very rapidly moving objects. It is an object of my invention to provide means. 5 ‘for producing light ?ashes having a very high order of frequency. ‘ Other and further objects and advantages will become apparent as the description proceeds. In accordance with my invention in itspre10 ferred form, I employ a cathode ray tube having a ?uorescent screen and means for causing cathode rays to impinge on the ?uorescent screen in- arrangement between them and the relative volt age applied is such as to diverge the cathode rays emanating from the cathode M. ‘ The tube is energized by a source of current l8 connected between the cathode l4 and the anode 5 It. Suitable means are provided for interrupt ing the cathode rays intermittently in order to cause intermittent energization of the ?uorescent screen i3, thereby producing light ‘?ashes for stroboscopic purposes. If desired, the interrup- 10 tion of the cathode rays may be produced by mak ing the energizing current source la a source of termittently with a high frequency. The tube is so arranged that the ?uorescent screen projects 15 the light upon the rapidly moving object to be alternating current. I In the arrangement of Fig. 1, I provide a volt age divider I9 connected between the terminals 15 Viewed 0!‘ provides a luminous background for Silhouetting the moving object. The invention Will be understood more readily ’ from the following detailed description When oon20 sidered in connection with the accompanying drawing and those features of the invention which are believed to be novel and patentable will be pointed out in the claims appended hereto. In the drawing, Fig. 1 is a schematic diagram repre25 senting one embodiment of my invention and Fig. 2 is a schematic diagram representing a mOdification of the apparatus of Fig. 1. Like reference characters are utilized in the drawing to of the current source l8 and connect the control electrode IT to an intermediate point on the volt age divider I9. The relative voltages of the elec trodes l6 and I‘! are such as to spread the cathode rays into a cone or a solid angle covering the 20 screen l3. Inasmuch as the ratio of the instan~ taneous voltages applied to the control electrode and the anode l6 determines the focusing or de gree of divergence of the cathode rays, it will be apparent that the focusing of the rays and the 25 illuminated area of the ?uorescent screen I3 is 30 unchanged by the variations in instantaneous value of the voltage of the source- i8. It will be designate like parts throughout. understood that, when the instantaneous value In the arrangement of Fig. 1. an electronic tube II is employed having an evacuated envelope l2 to 15 microns may be desirable- The tube ll may be similar to the known cathode ray tubes or to Braun tubes but preferably the cathode I4 is of relatively increased size and the other electrodes are suitably arranged to produce alight source of l'elatively large area at the fluorescent Screen '3 by having the cathode rays emerge in a divergent of the voltage falls below zero, or, in fact, below a given positive value, the emission of cathode rays will be cut o? and the screen l3 will become dark. The frequency of the light ?ashes produced by the ?uorescent screen will, therefore, coincide with the frequency of the alternating-current source is, The light produced by the ?uorescent screen 13 is caused to illuminate a, moving object which is to be observed. Such a moving object may, for example, be a rotating gear 20. If desired, the brilliancy of the ?uorescent screen I 3 may be diminished by ‘weakening the cathode rays and the rotating gear 20 may be observed by arrang ing the apparatus to bring the gear 20 between the ?uorescent screen l3 and the observer’s eye 2|, thus silhouetting the gear 20 against the flu orescent screen 13. When used for silhouetting, the surface of the screen I3 is preferably of such fan or cone-Shaped bundle Spread over substan- area as to subtend as great an optical angle as containing a fluorescent screen 13 at one end and a cathode H at the other end fol‘ producing radiant energy. preferably cathode rays or electrons 35 impinging upon the Screen l3- The Cathode M is preferably of the incandescent type having a source of current l5 for heating the Cathode to incandescence. If an incandescent cathode is employedthe envelope may be evacuated to ap40 proximately 301 micron on the other hand with a cold cathode air pressures as high as 5 r0 tially the entire surface of the screen l3. In addi, tion to the cathode I4, an anode I6 is provided 30 35 40 45 the moving object to be observed, such as the gear 50 20 or one of the teeth thereof. and preferably also a control electrode II. In It will be understood that, in viewing moving ‘ the arrangement of Fig. 1, the anode l6 and the objects stroboscopically, the object may be made control electrode I‘! are in the form of perforated to appear to stand still or to move very slowly by 55 disks, diaphragms or cylinders and the spacial ._ illuminating it with light ?ashes having the same 55 2,138,138 - frequency or a frequency nearly the same as that of the speed of revolution, speed of vibration, or in the case of gears and similar objects with re peated similar parts such as spokes or teeth the angular speed divided by the number of spokes, teeth, or other repeated parts. In order to adapt the apparatus for observation of parts moving at different speeds, it is desirable to employ means for varying the frequency of the light ?ashes. 10 For this purpose a suitable variable frequency al ternating current source may be employed at I 8, e. g. a variable frequency vacuum tube oscillator such as illustrated in Fig. 2. Although I have found that satisfactory results 15 may be obtained by utilizing an alternating cur rent energizing source to produce the interrup tions in the illumination of the ?uorescent screen, it will be understood that my invention is not limited to this precise arrangement. My inven 20 tion obviously includes other means for inter rupting the energization of the ?uorescent screen, such as means for causing cathode rays to sweep across the ?uorescent screen or around a target protecting the screen, or means for interrupting 25 the voltage applied to a control electrode. For example, in the arrangement of Fig. 2, I have shown a cathode ray tube ll having a cath ode I4 and an anode “3 corresponding to the cathode and anode of the apparatus of Fig. 1 but 30 energized by a direct-current source 22. The tube of Fig. 2 has two auxiliary electrodes which might be termed “control electrodes", one of which, the electrode 23, serves as a focusing elec trode for controlling the focusing of the cathode 35 rays and is connected to an intermediate tap of the direct-current source 22, and the other of which, in the form of a grid 24, is arranged to cut off the cathode rays in the usual manner by interposing a negative electrostatic ?eld. The 40 control electrode 24 may be utilized to produce intermittent illumination of the ?uorescent screen [3 by connecting a variable frequency al ternating-current source 25 between the cathode l4 and the control electrode 24. 45 Cathode rays will be caused to impinge upon the ?uorescent screen l3 with a frequency corresponding to the frequency of the variable frequency source 25 since, whenever the voltage of this source be comes negative, the cathode rays will be cut oil‘. 50 Inasmuch as stroboscopes employing cathode ray energized ?uorescent screens are of particular value for observing extremely high frequency phenomena for the reason that cathode rays lend themselves to control at considerably higher fre 55 quencies than the frequencies of light ?ashes which have hitherto been available in stroboscop ic apparatus, I prefer to provide a source of high frequency, such as a vacuum tube oscillator, for energizing the control electrode 24. Some por 60 tion of the vacuum tube oscillator circuits, such as an inductance or a condenser 26 may be made variable, and may be provided with a control handle extending from the casing of the oscilla tor 25 or with other suitable means to permit 65 varying the frequency of the light ?ashes illumi nating the moving object 20. If desired, instead of actually interrupting cath ode rays for the purpose of producing light ?ashes from the ?uorescent screen I3, I may cause the cathode rays to sweep across the ?uorescent screen I3. For example, by adding electromag netic beam control means, such as a coil, or elec trostatic beam control means, such as a pair of de?ecting plates 21, energized by a suitable source 75 of alternating current 28, I may cause the beam to sweep back and forth across the ?uorescent screen l3. Preferably, in this form, of the inven tion, the cathode l4 and the electrodes 23 and 24 are so shaped as to produce a flat beam in the form of a sheet of cathode rays in a plane per pendicular to the plane of the paper as seen in Fig. 2. The beam is thus fan shaped with the cathode rays spread across the solid angle which is subtended by the screen 13. By employing a fast ?uorescent screen, such as one comprising 10 calcium tungstate, the illumination of the screen will persist for a very short period of time after the cathode ray beam has passed across the screen and will be darkened in the interval be tween successive sweeps of the beam across the 15 ?uorescent screen l3. If desired the sweep plates 2'! may be so ar ranged in relation to the other electrodes that the cathode rays are swept beyond the ?uorescent screen to insure intermittent cessation of illumi 20 nation, or one or more targets 29 may be provided in one or more portions of the tube to inter cept the cathode rays during a portion of each successive sweep. I have herein shown and particularly described 25 certain embodiments of my invention and cer tain methods of operation embraced therein for the purpose of explaining its principle and show ing its application but it will be obvious to those skilled in the art that many modi?cations and 30 variations are possible and I aim, therefore, to cover all such modi?cations and variations as fall within the scope of my invention which is de?ned in the appended claims. What I claim as new and desire to secure by Letters Patent of the United Statesis: 1. In a silhouetting stroboscope, the combina tion of a cathode ray tube having a ?uorescent screen, and means within the tube for producing cathode rays, spreading them across a solid angle covering the screen and producing impingement 40 of said rays upon said screen intermittently at high frequency to form high frequency light ?ashes each extending over the area of said screen. 2. In a stroboscope for viewing rapidly moving 45 objects, the combination of a cathode ray tube with a ?uorescent screen for providing light, means for generating a divergent cone of cathode rays impinging on said screen and substantially covering it to cause it to produce light, and means 50 for interrupting at a high frequency the impinge ment of cathode rays on said screen to cause the light thereof to occur in high-frequency ?ashes. 3. In a stroboscope for viewing rapidly moving objects, the combination of an electronic tube with a ?uorescent screen for providing light, means within the tube for directing radiant ener gy against said ?uorescent screen and spreading said radiant energy across substantially the en tire surface ofv the screen to cause it to produce light over its area, and means for interrupting at a high frequency the impingement of radiant en ergy on said screen to cause the light thereof to ' occur in high-frequency ?ashes. 4. In a stroboscope for viewing rapidly moving objects, the combination of an electronic tube with a device for converting radiant energy into light, means Within the tube for directing a di vergent cone of radiant energy against said de 70 vice with the base of said cone substantially covering said device to cause it to produce light, and means for interrupting at a high frequency the impingement of radiant energy on said device 75 3. 2,183,188 to cause the light thereof to occur in high-fre quency ?ashes. 5. In a stroboscope for viewing rapidly moving objects, the combination of an evacuated dis charge tube containing a light-generating sur face, and means also contained within the tube for simultaneously energizing substantially the entire area of said light generator with interrup tions at high frequency. 10 6. In a stroboscope for viewing rapidly moving objects, the combination of a cathode ray tube with a ?uorescent screen for producing light, means for generating a fan~shaped bundle of cathode rays impinging on said screen and extending across its width to cause it to produce a line of light, and means for ‘sweeping said cath ode ray bundle transversely to itself across said screen beyond an edge thereof at high frequency to illuminate the entire screen and leave it dark 20 alternately thus causing the. light thereof to occur in high-frequency ?ashes. 7. In a stroboscope for viewing rapidly moving objects, the combination of a cathode ray tube with a ?uorescent screen for providing light, means for generating a divergent cone of cathode with a ?uorescent screen for’ providing light, an anode. a cathode and a beam cut-off control elec-' trode, a source of high-tension current connected between said anode and cathode, and a source of high-frequency alternating current connected be tween said cathode and control electrode. 10. In a stroboscope for viewing rapidly moving objects, the combination of a cathode ray tube with a ?uorescent screen for providing light, an anode, a cathode and a control electrode, a volt 10 age divider, and a source of alternating current of high frequency connected to said anode and cathode and to said voltage divider, said control electrode being connected to an intermediate part of said voltage divider. 11. In a stroboscope for viewing rapidly moving objects, the combination of a_ cathode ray tube with a ?uorescent screen for providing light, an anode and a cathode, a source of variable fre quency alternating current directly connected be 20 tween said electrodes, and means for varying the frequencythereof. ‘ 12. In a stroboscope for viewing rapidly moving objects, the combination of a cathode ray tube having a ?uorescent screen, means within the 25 rays impinging on said screen and substantially covering it to cause it toproduce light. and means for interrupting said cathode rays at a high fre high frequency impingement of said beam on said quency. screen. _ , 8. Ina stroboscope for viewing rapidly moving objects, the combination of a cathode ray tube with a ?uorescent screen for providing light, an anode and a cathode, and a source of high frequency alternating current directly connected between’ said electrodes. 9. In a stroboscope for viewing rapidly moving objects, the combination of a cathode ray tube 15 tube for producing'a cathode ray beam extending across said screen and means for interrupting at 13. In a stroboscope arrangement for viewing 30 rapidly moving objects, an evacuated discharge tube having a light generating surface, means contained within the tube for energizing inter mittently at high frequency substantially the en tire surface of said light generator simultane-' 35 ously. mrrz HAMACHER.