Photoelectric keyboard

BACKGROUND OF THE INVENTION

Photoelectric devices typically employ open light conducting channels through which light passes from a light source to one or more photosensitive devices. Such light conducting channels are not wholly satisfactory because they frequently become contaminated with oil, dirt, etc., and are thereby rendered less efficient, and because they usually necessitate the use of complicated shutter mechanisms in order to positively assure that light from the light source either will tie directed onto the photosensitive devices or will be prevented from striking the photosensitive devices as desired.

SUMMARY OF THE INVENTION

In the preferred embodiment of the invention a photoelectric keyboard is comprised of a plurality of photoelectric switches each including a light source, a photosensitive device adapted for actuation by light from the light source, a light conducting body positioned between the light source and the photosensitive device for directing light from the light source onto the photosensitive device and means for moving the body away from between the light source and the photosensitive device so that light from the light source is withheld from the photosensitive device.

DESCRIPTION OF THE DRAWING

A more complete understanding of the invention may be had by referring to the following detailed description when taken in conjunction with the drawing wherein:

FIG. 1 is a top view of a photoelectric keyboard employing the present invention in which certain parts have been broken away more clearly to illustrate certain features of the invention;

FIG. 2 is a partial sectional view of the left end of the keyboard shown in FIG. 1 taken along the line 2—2 in FIG. 1 in the direction of the arrows;

FIG. 3 is a sectional view taken along the line 3—3 in FIG. 1 in the direction of the arrows, and

FIG. 4 is a partial sectional view of the right end of the keyboard shown in FIG. 1 taken along the line 4—4 in FIG. 1 in the direction of the arrows.

DETAILED DESCRIPTION

Referring to the drawing, wherein like reference numerals designate like parts throughout the several views, and with particular reference to FIG. 1, there is shown a frame 10 comprised of a bottom plate 11, a front plate 12, a rear plate 13, a left end plate 14 and a right end plate 15. Mounted between the front plate 12 and the rear plate 13 are a pair of rods 16 and 17 each of which supports a plurality of springs 18. The springs 18 in turn support a plurality of light conducting bodies 20 each comprised of a straight, rigid cylinder of a light conducting material such as Lucite, fiber optics, etc., or of a hollow metal tube. Each of the bodies 20 is positioned in and extends between a pair of slots 21 and 22 in the left end plate 14 and the right end plate 15, respectively. As is shown in the FIGS. 2 and 4 the light conducting bodies 20 are normally held in engagement with upper surfaces 23 and 24 of the slots 21 and 22, respectively, by the springs 18.

Attached to the left end plate 14 is a subframe 25 which has a plurality of apertures 26 formed through it. The subframe 25 supports, preferably in the manner disclosed in the copending application of Arthur F. Lindberg filed in Oct. 5. 1966, Ser. No. 584,557, a plurality of photocells 27 each of which is individually aligned with one of the apertures 26. Attached to the right end hand plate 15 is a subframe 30 which, like the subframe 25, has a plurality of apertures 31 formed through it. The subframe 30 supports a plurality of light bulbs 32 each of which is individually aligned with one of the apertures 31. The subframe 25 is positioned with the apertures 26 in alignment with the slots 21 in the plate 14 and the subframe 30 is positioned with the apertures 31 in alignment with the slots 22 so that whenever a body 20 is in engagement with its surfaces 23 and 24 light is directed through a light conducting channel including a light bulb 32, an aperture 31, a light conducting body 20, an aperture 26 and a photocell 27.

The front plate 12 and the rear plate 13 each have a plurality of aligned holes 35 formed in them. Positioned in each set of aligned holes 35 is an encoder bar 40 which is connected to and spaced from a keytop 41, a body portion 42, a plurality of teeth 43 and a bar actuating key 41 by a spacer body 42. Bars 40 are spaced longitudinal and extend transversely of bodies 20. One or more selectively arranged fingers 43 comprise moveable encoding means and are carried from each bar 40 in spaced relation longitudinally thereof and in operative alignment with selected bodies 20, respectively. The bars 40 are slidably mounted in the frame 10 and are urged into the position shown in the drawing by compression springs 45 positioned around a plurality of spring arms 44.

Fingers 43 are formed so that they may be selectively broken away along lines 46 to encode the bars 40. For example, the second and fifth fingers 43 of the bar 40 shown in FIG. 3 have been broken away.

When the key 41 of an individual bar 40 is depressed, such bar moves downwardly against the action of its Springs 45. The light conducting bodies 20 aligned with any of the fingers 43 of the individual keytop 40 which have not been broken away are driven downwardly against the action of the springs 18 into either the dotted line position shown in FIG. 2 or the dotted line position shown in FIG. 4 depending upon the position of the individual bar 40 along the length of the keyboard. Whenever one of the light conducting bodies 20 is in either of the displaced positions, light is withheld from the photosensitive device 27 corresponding to the displaced body 20, and the photosensitive device is dark because the light conducting channel including the displaced body 20 is broken.

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When an individual key bar 40 is depressed, the light conducting bodies 20' aligned with lingers 43. which have been broken away are not moved out of the position shown in solid lines in the drawing. Accordingly, the light conducting channel extending from the light bulb 32 through the aperture 31, the light conducting body 20, and the aperture 26 to the photosensitive device 27 corresponding to any finger 43 which has been broken away is not broken and the photosensitive device 27 corresponding thereto is light.

The photosensitive devices 27 produce a first output when light is directed onto them by the light conducting bodies 20 and produce a second output when light is withheld from them due to the displacement of the light conducting bodies 20. Therefore, when a particular bar 40 is displaced the coding of the fingers 43 of the bar is transferred to the outputs of the photosensitive devices 27 in accordance with displacement of certain of the light conducting bodies 20 by the fingers 43 of the bar which have not been broken away and by the nonmovement of the light conducting bodies 20 corresponding to fingers 43 of the bar which have been broken away. The outputs of the photosensitive devices may be used as inputs to telegraph distributors, data storage devices, etc.

It should be understood that it is not necessary to 25 employ individual light bulbs as a light source and that any desired light source may be employed. It has been found, however, that it is useful to use a mask having apertures similar to the apertures 31 in conjunction with the particular light source employed in order to reduce 30 the amount of movement of the light conducting bodies 20 required to produce a change in the output of the photosensitive devices 27.