US2687337A - Slow speed time marker - Google Patents

Description

Aug. 24? 1954 l w. A. ALFORD 2,587,337

SLOW SPEED TIME MARKER Filed sept. 15, 1951 Patented Aug. 24, 1954 SLOW SPEED TIME MARKER Wayne A. Alford, Denver, Colo., assignor to Hathaway Instrument Company, Denver, Colo.

Application September 15, 1951, Serial No. 246,841

3 Claims.

'The present invention relates to a time marking device for oscillograph, and more particularly to an improved slow speed time marker` When oscillograph recording is done at slow speeds in a photo-sensitive record material moving at a speed of a few inches per second or slower, it frequently is desirable to have time coordinate lines on the chart paper at one second and at -second intervals. To obtain a record of proper accuracy and appearance, it is desirable to have these time coordinate lines of proper width and intensity.

Heretofore, time coordinate lines have been obtained by the use of an arrangement employing an electric switch which periodically illuminated a lament type lamp bulb. Light from this bulb was reflected to the recording charts material by means of a mirror and lens system. The time required for warming up the light bulb filament to incandenscence and the time required for incandescence to die out represented a denite time interval, making it impossible to produce a narrow time line. The electric switch in such arrangement generally was driven by a motor driven cam so that a variable time delay could be introduced unknown to the operator, therefore, producing inaccurate time coordinate lines.

In accordance with the present invention it is proposed to overcome the disadvantages of the prior art by an arrangement which will produce narrower time coordinate lines and in which no error can occure due to mechanical and electrical variations. This is accomplished by the use of a continuously illuminated lamp and a shutter arrangement so that light is emitted periodically.

It is therefore, an object of the present invention to provide a coordinate time marker for photo-sensitive cscillograph recording material which provides accuracy and time coordinate lines of the desired width.

A still further object of the present invention is to provide particularly for slowly7 moving record materials in an oscillograph, a slow speed time coordinate marker of improved construction.

Other and further objects of the present invention subsequently will become apparent by reference to the following description taken in conjunction with the accompanying drawing, Where- 1n:

Figure 1 is a side view of a slow speed time coordinate marker embodying the principles of the present invention; and

Figure 2 is an enlarged detailed view of a portion of the mechanism shown in Figure 1.

Referring to the drawing it will be seen that there has been shown a supporting panel I I which may be a portion of the oscillograph case or which may be a separate panel adapted to be mounted on the oscillograph case where an arrangement such as is to be described, is used as an accessory. The panel II is provided with a pair of binding posts I2 for supplying current to a synchronous electric motor, and another pair of binding posts I3 for supplying externally controlled current to the filament of an electric incandescent bulb. The front of the panel II carries a plate Ill secured by suitable screws I5 to an end plate I6, which supports a cylindrical tube I'I secured thereto by suitable fastening means which might include a plurality of screws I8. The cylindrical tube Il is fastened by suitable means, such as screws I9 to another end plate 2|. The end plate 2| is carried by a plurality of posts 22 which supports the frame of a self-starting synchronous alternating current motor 23.

The cylinder Il at an intermediate point, is provided with a longitudinal slot 26, the opening of which may be controlled by a shield 2d retained in proper adjusted position by a screw 25. Light emitted from the slot adjacent to shield 2t impinges upon a mirror 26 adjustably positioned between a pair of support arms 2'! secured to one side of the cylinder Il.

The end wall and support I6 of the cylinder Il is provided with a bearing support or sleeve eX- tension 2t for carrying a rod or tube 29. The sleeve 28 is provided with a slot 3| which is engaged by a pin 32 carried by the rod 2Q. The rod 29 which extends to the front of the panel I I is provided with a knob 33 so that the rod 29 may be reciprocated by an amount determined by the pin 32 operating within the slot 3l of the bearing support 28. At the other end of the rod 29, there is located a cylindrical support 3e which carries a socket 35 for an incandescent bulb 3S. The bulb 36 serves as the light source which is emitted periodically to impnge upon the mirror 26 from which it is reflected to the photo-sensitive record material of the oscillograph.

The lamp -36 is surrounded by a shutter comprising two concentric cylinders shown in detail in Figure 2. The synchronous electric motor 23 has a shaft 3l which carries a gear 38 formed at one end of a sleeve 39. The sleeve 39 `at its outer end carries a cylindrical support element tl upon which is secured a cylinder 42 having a single longitudinal slot therein.

The gear 38 engages a reduction gear 43 carried by an auxiliary shaft lill. The gear 43 is connected to a smaller gear 46 which drives a larger gear 47. The gear 41 is carried by a sleeve 48 extending through the end Wall 2l of the cylinder l1. On the other end of the sleeve 48 there is mounted a cylindrical support 5I which carries a slotted cylinder 52 which is of larger diameter than the cylinder 42. In order to prevent light from leaking along the sleeve 48 a suitable felt washer 53 is retained in position by a collar 54.

The manner in which the apparatus operates will become more apparent by referring to a particular embodiment wherein the synchronous motor 23 had a speed of 60 R. P. M. for its shaft 3l. The inner shutter and cylinder 42 having a single slot therein, therefore, rotated at 60 R. P. M. The speed of the outer cylinder 52 was reduced to 6 R. P. M. The outer cylinder 52 in this particular embodiment was provided with 9 slots 55 and one slot 56. The slots 55 and 55 were disposed at equal angles about the circumference of the cylinder 52. The inner cylinder 42 has a single slot of substantially the same width and length as the slot 55. With the lamp in the position shown in Figure 1, light will be transmitted through all of the slots 55 and 55 to the mirror 25 so that a flash of light is emitted once every second. If the lamp 38 is now moved toward the right, a distance determined by the length of the slot 3l in the sleeve 28, the iilament of the lamp will be aligned with the outer portion of a slot 56 and no light will be transmitted through the slot 55. In this case, light will be transmitted to the mirror 25 once every 10 seconds. Thus, by mere actuation of the knob 33 the lamp 38 may be withdrawn to provide a greater time interval between the flashes of light which produce the time markers on the oscillograph records. In order that the motor 23 might be supported with proper rigidity there is provided a pin 57 which fits into a suitable support.

While, for the purpose of illustrating and describing the present invention a preferred embodiment has been shown in the drawing, it is to be understood that the invention is not to be limited thereby since such variations are contemplated as may be commensurate with the spirit and scope of the invention set forth in the accompanying claims.

I claim:

1. A slow speed time coordinate marker for an oscillograph comprising a synchronous alternating current motor, two coaxially arranged longitudinally slotted cylinders, gear means interposed between said cylinders and said motor for rotating said cylinders in the same directions at different speeds, one of said cylinders having a larger number of slots than the other cylinder and certain of said slots being shorter than the others, at least one of said slots being as long as the slot in the other cylinder, a source of illumination coaxially located within said cylinders, and a third longitudinally slotted stationary cylinder surrounding said former cylinders having' an adjustable shield for controlling the light emitted therefrom.

2. A time coordinate marker for an oscillograph comprising a longitudinally slotted cylinder mounted for rotation about its axis, a second longitudinally slotted cylinder coaxially surrounding said rst cylinder and mounted for rotation about its axis, said second cylinder having a plurality of slots shorter than the slot in said first cylinder and at least one slot as long as the slot in said first cylinder, a source of illumination coaxially located within said cylinders and mounted for limited reciprocable axial movement, and a third longitudinally slotted cylinder surrounding said former cylinders having an adjustable shield for controlling the time during which light is emitted therefrom. 1

3. A time coordinate marker for an oscillograph comprising a longitudinally slotted cylinder mounted for rotation about its axis, a second longitudinally slotted cylinder coaxially surrounding said iirst cylinder and mounted for rotation about its axis, means for driving said cylinders at different constant speeds, said second cylinder having a plurality of slots shorter than the slots in said iirst cylinder and at least one slot as long as the slots in said iirst cylinder, a source of illumination coaxially located within said cylinders and mounted for limited reciprocable movement to determine whether or not light shall be transmitted through said shorter slots, and a third slotted cylinder surrounding said former cylinders having an adjustable member on said cylinder for controlling the effective aperture of the slot of said cylinder.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,859,828 Jenkins May 24, 1932 2,424,981 Harrison Aug. 5, 1947 2,428,369 Kammer Oct. 7, 1947 2,578,877 Brownlow Dec. 18, 1951

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