| 摘要 |
An optically activated keyboard provides inputs to a digital computer or the like. The keyboard includes a key housing having formed therein a wave guide matrix of intersecting columns and rows with light emitting diodes (LED's) installed in one end of each column and photo transistors installed in one end of each row. A plurality of keys are mounted at the top surface of the housing, each key having a plunger which projects through a corresponding aperture in the housing, when the key is depressed. The intersections of the columns and rows are located directly beneath the apertures so that when a key is depressed, its plunger intrudes into the volume at the intersection. Each plunger, in concert with the wave guide intersection, forms a light polarizing system. In the preferred embodiment, each plunger has a reflecting face that is angled to reflect light from the LED in the corresponding column into the corresponding row, finally impinging against the appropriate photo transistor. In this preferred embodiment, when the button is fully depressed, the plunger provides space between the bottom of the plunger and the bottom of the wave guide so that light traveling in the column or row is permitted to pass and thereby to detect any other keys that have been depressed in the particular column or row.
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