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United States Patent 3,747,321
Yudewitz July 24, 1973



A clock that provides visual and electrical output signals that may be used, for example, to record time-controlled operations is shown and described. An endless tape encoded to indicate discrete increments of time through a pattern of translucent and opaque portions is driven continuously and at a uniform rate of speed in order to complete one full revolution in each 24 period. As the coded portions of the tape are drawn in sequence past a photoelectric reader, the electrical output generated in response to specific luminous stimuli is fed through a decoder to operate or record upon an output device which may be one of a number of suitable conventional devices, e.g. a tape recorder, a printer, a record chart, etc.

Inventors: Yudewitz; Norman (Westport, CT)
Assignee: Pitney-Bowes-Alpex, Inc. (Danbury, CT)
Appl. No.: 05/240,504
Filed: April 3, 1972

Current U.S. Class: 368/82 ; 368/234; 368/41; 968/565
Current International Class: G04C 17/00 (20060101); G04b 003/00 ()
Field of Search: 58/23R,23C,5R,152R 250/215X,219X 346/20 340/347

References Cited

U.S. Patent Documents
3136117 June 1964 Speiser
3290507 December 1966 Flieg et al.
3372240 May 1968 Boyers et al.
3546470 October 1970 Junkert
Primary Examiner: Wilkinson; Richard B.
Assistant Examiner: Jackmon; Edith C. S.


I claim:

1. An apparatus for generating time signals comprising in combination a rotary drive means adapted to produce a rotary output motion which is related to the passage of time, a rotatable and flexible endless web coupled to said drive means, said web having opaque and translucent regions arranged in a coded pattern that each correspond to discrete times, a light source positioned on one side of said web so as to project light through the translucent regions of said web adjacent to said light source, an array of photoelectric cells arranged so that the individual cells of the array are aligned transversely to the direction of web motion to register light from said light source transmitted through said translucent regions of said web and generate an electric signal that corresponds to one of said discrete coded times in response to each of said light signals received, a visual numerical time display synchronized with said encoded web, means for manually adjusting the time indicated by the apparatus to some predetermined standard time, and a housing for substantially excluding stray light from said combination.

2. The combination of claim 1 wherein said translucent regions of said encoded web comprise punched holes.

3. The combination of claim 1 wherein said translucent regions of each of said coded patterns comprises a plurality of continuous bands that commence at the termination of one coded pattern and terminate at the commencement of still another of said coded patterns.

4. A combination according to claim 1 further comprising signal decoding means responsive to said generated photoelectrical signals for converting said signals into another signal that is related to the numerical value of the time signal.

5. A combination according to claim 4 further comprising a plurality of gate means for applying said photoelectric signals to said decoding means in response to the alignment of one of said coded patterns with said photoelectric cell array.

6. A combination according to claim 5 further comprising memory means electrically coupled between said plurality of gate means and said decoding means to continue to apply a signal to said decoding means if one of said coded patterns is not aligned with said photoelectric cell array.


1. Field of the Invention

The invention relates to timing equipment, and more particularly, to apparatus that converts coded photoelectric signals into recordable digital time signals.

2. Background of the Prior Art

The apparatus that characterizes the invention is generally useful when employed to provide an indication of time in conjunction with an operation which is also being recorded in order to establish the time when the operation in question occurred.

It is well recognized that industrial and scientific operations, for instance, laboratory test runs in the chemical process industries and in medical monitoring devices require some means for indicating the precise time of recording various information. Illustratively, a record of this nature should provide the exact time a change in some condition occurred so that an appropriate action can be taken.

There are a number of commercial devices that tend to serve this purpose. Generally, however, these commercial devices are elaborate, expensive, and involve complex electrical circuits. Consequently, these devices are primarily employed in applications that are economically justifiable.

Accordingly, there is a need for a device that is inexpensive, simple in construction, and reliable in operation in order to satisfy a far broader range of operations.

It is an object of the present invention to provide an inexpensive and reliable photoelectric device for generating time signals.

Another, and more particular object of the invention is to provide a photoelectric time apparatus in which a continuous flexible web bearing encoded data that is representative of time completes one full revolution in each twenty-four hours past a photoelectric detector to generate an output signal that is decoded into another signal to operate or record upon an output device.

It is still another object of the invention to provide a time recording apparatus that uses an endless belt which is encoded with time data either in the form of punched holes or a combination of relatively translucent and opaque segments that is representative of the time code.

Still another object of the invention is to provide an automatic recording and reproducing apparatus in which a time indicating signal can be simultaneously detected and recorded.


These unsatisfactory features of the prior art are avoided and the objects of the invention are attained through an apparatus in which a chart or clock drive motor draws an endless belt between a lamp and a photoelectric reader. An array of individual groups of translucent and opaque portions of the belt, e.g. punched holes in a paper web, is arranged transverse to the direction of the belt's movement. Each of these individual groups correspond to a discrete time. Preferably, the motor moves each of these groups past the lamp and photoelectric reader combination once in each 24 hour period, although other time sequences may be substituted if desired under the circumstances. The lamp light transmitted through the translucent parts of each group on the belt in turn stimulates a unique electrical response in the photoelectric reader that registers the time at the moment of stimulation.

In one embodiment of the invention, the belt is provided with a set of sprocket apertures that are uniformly spaced from each other in the direction of belt movement. The teeth of a sprocket on the clock drive motor shaft engage the belt through these apertures in order to positively drive the belt at a predetermined speed. These apertures also provide a gating signal. For example, as an aperture associated with a specific time code group is drawn abreast of the lamp and reader, light passes through the aperture and stimulates the photocell in the reader associated with the sprocket apertures to produce a signal which indicates that one of the coded time groups is in alignment with the lamp and photoelectric reader. The photoelectric response signal caused by the light shining through the sprocket aperture is sent to an array of AND gates. Other photocells, responding to light passing through those translucent portions of the time code group that is aligned with the reader also are registered at some of the AND gates in the array. Those AND gates that simultaneously receive two signals, the sprocket aperture and the coded hole signals, are enabled, or opened, and thus pass signals to a decoder circuit which converts the input signal combination from the AND gates into, for example, an analog signal that is proportional to a specific time in a 24 hour clock sequence.

As the belt moves past the lamp and stops the transmission of light, all of the AND gates are disabled and the signal output from the decoder circuit is likely to terminate. To prevent this effect, and to provide a continuous reading output from the clock, a shift register, or other suitable temporary data storage device can be coupled between the array of AND gates and the decoder. Circuit arrangements of this sort continue to apply the last received time signal to the decoder until the stored signal is supplanted by a new signal from the AND gates.

As an alternative to the temporary data storage circuit described above, a belt that permits the uninterrupted transmission of coded light to the photoelectric reader also provides a continuous clock output. For example, an endless belt of motion picture film characterized by continuous opaque and translucent bands for each of the individual code groups which terminate only at the initial portion of the next time code group in the sequence will provide a continuous clock output. In this latter example, moreover, the AND gates described in connection with the preceding illustration are not necessary to the function of the invention.

These and other objects of the present invention will become apparent from the description which follows when considered in conjunction with the accompanying drawing.


FIG. 1 is a perspective view, in part schematic, of a typical apparatus that characterizes the principles of the invention;

FIG. 2 is a schematic diagram of a portion of the circuit used in connection with the embodiment of the invention shown in FIG. 1;

FIG. 3 is a segment of an alternate belt for use in connection with the invention.


Briefly, the novel recording, reproducing and visual time display apparatus that characterizes the invention is constructed and operated in the following manner, reference being made to FIG. 1 of the drawing.

A clock or chart drive synchronous motor 12 is suitably mounted in a housing 11. Preferably, the housing 11 is substantially light-tight to prevent stray or background light from improperly activating a photocell bank or reader 27. The motor 12 connected through shaft 14 to a slip clutch 15 drives an endless web, belt or punched tape 21 in the direction of the arrow. The tape holes are organized into individual groups that are transverse to the direction of tape travel. Each of these groups represents a specific time that is encoded by means of holes 22. The perforations code can identify any desirable division of time, e.g. hours, minutes and seconds, in, for example, a binary coded decimal system. The tape is carried by a driven sprocket drum 17 mounted on connecting shaft 16. An idler drum 18 also is mounted on a shaft 19 to carry the opposite loop of the tape 21 from the sprocket drum 17. A spring 20 secured to the idler drum shaft 19 or other suitable arrangement applies a moderate tension on the perforated endless web 21 to reduce the possibility for slippage of the web 21. The belt 21 is shown with center line sprocket apertures or aperture 23 which enable the sprocket teeth to engage and move the belt 21. The apertures 23 also may be utilized in the code through a logic circuit (not shown in FIG. 1) which responds to the electrical response of the photocell bank 27 to the light that is transmitted through these apertures. When functioning solely as a belt driving means, however, sprocket perforations, of the kind shown at 58 in FIG. 3, may be positioned in a peripheral track 50 at the outer edge of the belt, rather than the central apertures 23 illustrated in FIG. 1.

The motor 12 turns the shaft 14 at a speed which is proportional to the passage of time. The motor gear box 13 reduces the speed of the shaft 14 in order to turn the sprocket 17 through one complete revolution in each 24 hour period.

The slip clutch 15 enables the sprocket 17 to be reset manually to match some predetermined time reference. It is used to provide slippage against the high torque resulting from the large gear ratio in the motor, during manual reset only.

The tape 21 preferably is made of durable material, such as Mylar film which is substantially opaque save for the holes 22 that are arranged in a binary coded pattern. As the tape or web 21 rotates, the holes 22 presented to the photocell array 27 appear in a binary coded sequence representative of the particular time. A lamp 28 is positioned to provide a light source that enables the photocell array 27 to detect simultaneously a whole transverse line of holes 22 formed in the web 21 and representing a binary coded time. The spacing between the individual holes 22 in the direction that is transverse to the direction of belt movement corresponds to the spacings of the individual photocells in the array 27. Thus, the holes in the belt are aligned with the individual photocells in the reader 27. Consequently, the light from lamp 28 is transmitted through the holes 22 to the respectively associated individual photocells of the array 27.

Mounted contiguous to the web 21 and synchronized therewith is a second belt, tape or web 36 on which the time of day is visually represented, e.g. by the hours of the day 37. The time scale may be divided into suitable proportion as shown at 38. Web 36, moreover, is mounted in a manner that is similar to the web 21. As shown, the endless web 36 on which the time scale has been imprinted is driven by a sprocket drum 31 which is carried on a shaft 30 at one end of the tape 36. An idler drum 33 also is mounted on shaft 32 in order to engage the opposite loop of the tape 36 from the sprocket drum 31. A spring element 34 functions in a manner similar to spring 20 in order to maintain proper belt tension and balance the forces applied by the tensioning spring 20 to the shaft 19.

As shown, the housing 11 is provided with an opening or transparent window 40 through which a segment of the web 36 may be viewed. An index line 39 or other suitable indicator mark is used to designate the exact time.

A thumbwheel reset 43 is mounted on connecting shaft 42 to permit the time to be reset via the slip clutch 15. A portion 44 of the thumbwheel 43 is allowed to protrude through an opening in the housing 11 for this purpose.

In operation, a sprocket aperture passes in front of the respective photocell (not shown) in the reader 27; a "one shot" multivibrator 60 (FIG. 2) is triggered by the signal from the respective photocell. The signal from the multivibrator 60 is combined in at least some of the AND gates in the group 61 with the output signals of those photocells that are aligned with punched holes 22 in the tape 21 (FIG. 1). These combined signals enable the gates which apply output signals to a decoder 62 (FIG. 2) to operate or to record on an output device 63, which can be a tape recorder, a printer, or a record chart. Preferably, the decoder 62 may comprise an ordinary digital-to-analog converter circuit that translates the gated binary coded decimal signal into another signal, the amplitude of which, for example, is directly related to the numerical value of the recorded time.

When using the apparatus of the invention as a continuous reading clock with punched tape, there is a period of time during which light transmission to the photoelectric reader 27 (FIG. 1) is obscured, i.e. when the belt 21 is between sprocket apertures. To keep the time data available during this blackout period, a temporary storage device such as a shift register (shown as the memory 64 in FIG. 2) should be coupled electrically between the decoder 62 and the AND gate array 61. The information stored in the shift register remains until a new strobe pulse or gating signal from the multivibrator 60 erases the stored data and prepares the register for the reception of new information. The shift register may also be used to organize the information for presentation to serialized type output recorders.

Illustrated in FIG. 3 is a segment of an alternate form of an endless web or tape 50. The embodiment may comprise any suitable material such as Mylar motion picture film which contains continuous bands of opaque and transparent rectangles 52 and 54, respectively, which may be either imprinted or photographically recorded. This embodiment also illustrates a segment shown within bracket 57 that presents a numerical value for the recorded time. Consequently, the numerical time scale 56 may be combined with the digitally encoded portion within bracket 55 in order to combine coded and visual decimal time data on a single web, rather than on the separate webs 21 and 36 of FIG. 1. Conventional sprocket holes 58 of the kind ordinarily used to drive motion picture film are provided at each side of the web 50.

While the invention has been described by reference to particular embodiments in order to illustrate the invention with greater particularity, various changes or modifications of these embodiments will occur to those skilled in the art and these may be made without departing from the scope or spirit of the invention as set forth in the claims.

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