US3539723A - Transmitting typewriter apparatus - Google Patents

Description

W. W, 19% c. F. MATTKE ,39,723

TRANSMITTING TYPEWRITER APPARATUS Filed Aug. 1, 1967 FIG 3 FROM OTHER THRESHOLD CCTS THRESHOLD E UT/L/ZAT/ON C/RCU/T C/RCU/T KEV/NC C/RCU/f \87 22 rai JLLQW 42 INVENTOP CF MA TTKE ATTORNEY United States Patent 3,539,723 TRANSMITTING TYPEWRITER APPARATUS Charles F. Mattke, Fanwood, N.J., assignor to Bell Telephone Laboratories, Incolporated, Murray Hill, N.J., a corporation of New York Filed Aug. 1, 1967, Ser. No. 657,599 Int. Cl. B41j 3/50; H041 15/12, 15/20 US. Cl. 178-81 5 Claims ABSTRACT OF THE DISCLOSURE This disclosure describes means for generating coded electrical signals corresponding to a character typed at a typewriter. The typewriter is especially adapted by the addition of photoelectric code-sensing elements. Coded light reflecting markings corresponding to each character typed are deposited on the corresponding type bar adjacent the type head. When a key is struck the head of the type bar corresponding to the character is brought into coincidence with the sensing elements. Channeled light beams are selectively reflected from the depositions and impinge upon the sensing elements, thereby generating a coded electrical output.

BACKGROUND OF THE INVENTION This invention relates to transmitting typewriter apparatus, and more particularly to apparatus for producing contemporaneous electrical coded signals corresponding to a character that is typed.

There are numerous techniques for modifying conventional typewriters so as to produce electrical output signals indicative of each character typed. These output signals may then be utiilzed in some auxiliary apparatus, such as a slave typewriter or other printing mechanism. More recently, these coded signals have served as input data to electronic computers.

One system utilizes electrical contacts which are physically closed by the depression of a typewriter key andwhich control auxiliary relays to drive an output device. In another system a typewriter is provided with key-operated permutation bars which are utilized to actuate combinations of electrical contacts for producing output signals to drive an output device.

Another system utilizes optical means in the form of shutters which are attached to each of the key levers for interrupting a beam of light when the key is actuated. The shutters are provided with combinations of openings corresponding to the code designations for the respective characters being typed. The coded light output pulses may be utilized to drive or control some output apparatus.

While the above prior art systems have been effective to provide output signals from a typewriter corresponding to the character typed, they have been unsatisfactory in one or more ways. They all involve either extensive and inconvenient modifications to existing typewriters, or a considerable amount of additional apparatus on a new typewriter. Further, the optical system described above requires the accurate positioning of the light source and shutter bars within the typewriter housing, thus adding to the complexity and maintenance problems of the machine.

Other efforts to provide apparatus for simply and economically generating coded characters in connection with the operation of a conventional typewriter include that described by R. B. Johnson, et al., in US. Pat. No. 3,018,332 issued Jan. 23, 1962. The apparatus described therein includes means for selectively interrupting a continuous magnetic field by a type bar in accordance with perforations made in that typed bar. While effective for many purposes, this system requires that rather complex 3,539,723 Patented Nov. 10, 1970 ICE modifications be made to the typewriter. More particularly apparatus must be provided and properly aligned in a position astride the struck type bar. Further, the type bars themselves need be permanently modified by perforating them in accordance with the coded representation they must bear.

Grazebrook, in British patent specification 1,040,580, published Sept.' 1, 1966, describes apparatus for simultaneously typing and electrically encoding. According to that specification, characters typed on a page are detected by light sensing means arranged adjacent each newly typed character. Light is reflected from the typed character to the sensor and is converted into corresponding electrical pulses. A major disadvantage of this technique is that the character typed on the page must be of a special not-easily-read form if reasonably simple sensors are to be employed. A similar character-recognizing technique has been employed in banking systems for some time for detecting account numbers and other information printed on checks with special ink.

Other efforts for providing coded electrical outputs corresponding to typed characters may be found, for example, in British patent specification 1,028,059 published May 4, 1966. That specification describes piezo-electric means subjectedto vibratory strain upon depression of a typewriter key. Apparatus of this kind typically requires a large number of piezo-electrical elements and corresponding multiplicity of coupling and vibration means.

Briefly, the present invention provides simplified means for generating coded electrical signals corresponding to characters that are typed, by modifying corresponding type bars by the selective deposition of light-reflecting substances on them. Means are then provided for causing light to impinge upon these type bars and subsequently to collect light selectively reflected from them. The reflected light is then easily converted into coded electrical signals. This technique is implemented in a very compact manner with substantially all alignment problems taken care of prior to installation on any one of many conventional typewriters. Further, the present invention requires no permanent modification to the typewriter itself. The light reflecting deposits in the form of coded markings may be easily removed or modified in a manner not unlike that used to clean a type bar.

These and other aspects of the present invention will be more fully described below with reference to the included drawings, wherein:

FIG. 1 shows one embodiment of the present invention in position on a typewriter.

FIG. 2 shows in more detail the reflective aspects of the present invention as embodied in the apparatus of FIG, 1.

FIG. 3 shows details of the light sensing elements of the apparatus of FIG. 1 and the conductors attached to them.

FIG. 4 shows additional circuitry to be used with the configuration shown in FIGS. l-3.

FIG. 5 shows a miniaturized version of the present invention.

DESCRIPTION OF THE INVENTION FIG. 1 shows one embodiment of the present invention in position on a typewriter of standard design. A housing 10 is affixed by a bracket (not shown), or other suitable means, to the typewriter frame at a convenient point adjacent the path traversed by the typical type bar 20 when the corresponding key is depressed. The housing 10 may have the shape of a rectangular parallelepiped or, advantageously may have the wedge shape shown in FIG. 1. One face of housing 10 is advantageously arranged to be in a plane substantially parallel to the plane in which type bar 20 moves when in the vicinity of platen 25. A plurality of apertures 35 are provided in this face at points selected to be in proximity to designated points on type bar 20 while the latter is in the vicinity of platen 25.

Each aperture 35 forms the junction of a source channel 40 and a reflection channel 50. Source channels 40 are arranged to channel light from light source 30 to respective apertures 35. Reflection channels 50 are arranged to channel light entering respective apertures 35 from outside housing to light sensitive wafers 60.

Each type bar is modified by the deposition of a light reflecting material on it, preferably on or near its head 22. These deposits advantageously take the form of marks having substantially the same shape as apertures 35. The deposits are illustratively made by applying a light-reflecting paint, metallic suspension, or adhesivebacked reflecting tape. FIG. 3 illustrates the light reflecting deposits 70 in the form of a plurality of marks equal in number to the number of apertures 35 provided in housing 10. These marks 70 are typically arranged to coincide with respective apertures when type bar head 22 is adjacent platen 25. To uniquely code a particular character other than that shown, some permutation of such marks fewer in number than the total number of apertures 35 need be provided.

FIG. 2 illustrates more fully the operation of the embodiment of the present invention shown in FIG. 1. Light originating at light source is channeled by a typical source channel 40 to corresponding aperture 35. When the head 22 of type bar 20 is in position adjacent housing 10', and the coded marks corresponding to the key struck are such that a reflecting deposit 70 is in coincidence with aperture 35, light being channeled along a source channel 40 will emanate from aperture and impinge on reflective deposit 70. This light will then be reflected back into aperture 35, but at such an angle as to be channeled by a reflection channel 50.

Light-sensitive wafer 60 is positioned at the end of reflection channel 50 opposite aperture 35. This wafer generates an electrical signal upon being struck by light such as that reflected by the marks 70 on type bar 20. These electrical signals are delivered to a utilization circuit by way of suitable conducting means such as the metallic wool 80 and wire 90 shown in FIG. 2.

If the code corresponding to the typewriter key depressed did not include a mark 70 which would be in coincidence with the particular source channel shown, no light would be reflected and no electrical signal would be supplied on the corresponding wire 90. By suitably selecting the permutation of reflective marks 70, any desired binary electrical code can be generated on the wires 90, each of which corresponds to a pair of light channels and 50.

Light channels 40 and are advantageously positioned at equal angles with respect to the plane in which the head 22 of type bar 20 travels when in the vicinity of housing 10. This arrangement ensures that a maximum amount of light from source channel 40 is reflected into channel 50 and thence to light sensitive wafer FIG. 3 further illustrates mechanical details facilitating an understanding of the illustrative embodiment shown in FIG. 1. A type bar head is shown at 22 when in position to strike platen 25 and at 22 at a preceding point in time as it was passing the plurality of apertures 35. The position of the light-reflecting marks or deposits and the apertures 35 can be arranged to be selectively in coincidence at any convenient time during the transit of type bar 20. That is, the electrical signals resulting from the selective reflection can be generated as the character is actually typed, or at some time prior to or later than this time while the type bar is advancing toward or retreating from the platen 25.

FIG. 4 shows a useful addition to the embodiment shown in FIGS. 1-3 and described above. To minimize Cir spurious signals resulting from light sources other than that in housing 10 and from reflections from objects inadvertently placed adjacent apertures 35, a threshold circuit is connected to each output wire 90. This circuit is adjusted to respond only to signals having an amplitude sufficient to indicate a reflection from a coded reflective mark 70. As a further refinement, threshold circuit $5 is arranged to be responsive only to signals of frequency or duration characteristic of light source 30 and. system geometry.

To further control the signals produced on leads 90, a keying circuit '87 is provided in certain cases. This circuit produces a gating signal upon the depression of any key which typically unclamps the output of threshold circuit 85 and simultaneously notifies the utilization circuit 86 that coded signals can be expected. Keying circuit 87 is typically activated by mechanical coupling to each key or by an additional light-sensing element responsive to light reflected prior to the presentation of the coded markings 7 0 at the apertures 35.

Although the code markings 7 0 are shown in a. vertical row in FIG. 3, no such limitation is inherent in the present invention. It, for example, the markings are arranged in a line at an angle to the vertical, while the apertures 35 are maintained in a vertical line, output pulses on wire 90 will not occur simultaneously, for all code positions but will occur in time sequence. Other arrangements of the relative positions of the reflective markings and apertures 35 are, of course, possible and will occur to those skilled in the art.

One advantage realized by not having all output pulses occur simultaneously is that a threshold circuit 85 need not be provided for each code digit, but can be timeshared, i.e., the output signals are time-multiplexed. Keying circuit 87 is then used to initiate a scanning by the input to threshold circuit *85 over the plurality of output wires 90.

While light channels 40 and 50 are shown in FIGS. 1-3 as hollow tubular passages, they may readily take other forms. For example, fiber optic materials may be used to conduct light from light source 30 to aperture 35 and after reflection from a marking 70 to a light sensitive wafer 60.

Likewise, light source 30- need not be a lamp of the form shown in FIGS. 1-3, but rather may be any source of radiation susceptible of selective reflection and subsequent detection by an appropriate sensor. In particular, any one of many well-known semiconductor light-emitting devices, described for example in Scientific American, May 1967, p. 109, may serve as sources of light responsive to steady electrical signals or pulses generated by keying circuit 87.

Modern techniques of miniaturization are readily applicable to the present invention. According to one application of these techniques to the present invention, the light source 30 and one of its corresponding source channels 40 are reduced to a single light-emitting semiconductor junction device. Likewise, light-sensitive slab 60 and its associated channel 50 are reduced to a single lighsensitive semiconductor junction device. The two junction devices are then oriented properly relative to each other so that a substantial portion of the emitted light is reflected from the reflective marks 70 to the light-sensitive junction.

FIG. 5 shows a schematic representation of one miniaturized version of the present invention. The elements are not necessarily drawn to scale. Light is emitted from source 42 either on a steady or pulsed basis. Barrier 12 prevents light from source 42 from striking light sensitive device 52 except by way of reflection from marking 70 on type bar head 22. Source 42. and sensing device 52 each comprise a semiconductor junction of the types described above and along with barrier 12 are typically positioned on a common substrate by well-known techniques. Likewise, the source 42 and sensing device 52 corresponding to each code marking 70 are positioned on a common, essentially 2-dimensional, wafer.

The use of a light source for each code marking position may of course be used in other applications where desired.

What is claimed is:

1. Transmitting typewriter apparatus comprising (A) a typewriter having a platen, a plurality of individually selecta ble keys and corresponding selectable type bars, said type bars being operative to rnove to a point adjacent said platen in response to the selection of a corresponding one of said keys, each of said type bars having at least one unique reflecting marking,

(B) a source of radiant energy,

(C) means for conducting said radiant energy from said source to a point adjacent said reflecting markings when a selected one of said type bars is in a position adjacent said platen,

(D) a plurality of photoelectric devices for generating signals in response to applied radiant energy, and

(E) means for conducting radiant energy reflected from each of said markings on said selected one of said type bars to corresponding photoelectric devices.

2. Apparatus according to claim 1 further comprising a threshold device responsive to input signals from said photoelectric devices for producing output signals whenever said input signals have magnitude greater than a preselected value, thereby to exclude spurious low level signals corresponding to ambient radiant energy.

3. Apparatus according to claim 1 wherein said source of radiant energy comprises a source of visible light.

4. Apparatus according to claim 1 wherein each of said means for conducting comprises a fiber optic strand.

5. Apparatus according to claim 1 wherein said source of radiant energy is arranged to generate radiant energy having frequency components having substantial amplitude at preselected frequencies, said preselected frequencies being exclusive of those frequencies at which ambient radiant energy has substantial amplitude, and wherein said photoelectric devices are arranged to be responsive to radiant energy having substantial amplitude at one or more of said preselected frequency components.

References Cited UNITED STATES PATENTS 2,987,249 6/ 1961 Van Vechten 178-17 3,018,332 1/1962 Johnson et a1. 197-1 3,122,237 2/1964 Stenstrom 250-219 3,241,648 3/1966 Stenudd 1971.5

THOMAS B. HABECKER, Primary Examiner M. M. CURTIS, Asistant Examiner US. Cl. X.R.

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